WO2000000146A2 - High flux liquid transport members comprising two different permeability regions - Google Patents
High flux liquid transport members comprising two different permeability regions Download PDFInfo
- Publication number
- WO2000000146A2 WO2000000146A2 PCT/US1999/014796 US9914796W WO0000146A2 WO 2000000146 A2 WO2000000146 A2 WO 2000000146A2 US 9914796 W US9914796 W US 9914796W WO 0000146 A2 WO0000146 A2 WO 0000146A2
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- liquid
- region
- transport member
- liquid transport
- member according
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- A—HUMAN NECESSITIES
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- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/36—Surgical swabs, e.g. for absorbency or packing body cavities during surgery
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- B65D47/00—Closures with filling and discharging, or with discharging, devices
- B65D47/04—Closures with discharging devices other than pumps
- B65D47/20—Closures with discharging devices other than pumps comprising hand-operated members for controlling discharge
- B65D47/2018—Closures with discharging devices other than pumps comprising hand-operated members for controlling discharge comprising a valve or like element which is opened or closed by deformation of the container or closure
- B65D47/2031—Closures with discharging devices other than pumps comprising hand-operated members for controlling discharge comprising a valve or like element which is opened or closed by deformation of the container or closure the element being formed by a slit, narrow opening or constrictable spout, the size of the outlet passage being able to be varied by increasing or decreasing the pressure
Definitions
- High flux liquid transport members comprising two different permeability regions
- the present invention relates to liquid transport members useful for a wide range of applications requiring high flow and/or flux rate, wherein the liquid can be transported through such a member, and/ or be transported into or out of such a member.
- Such members are suitable for many applications, as - without being limited to - disposable hygiene articles, water irrigation systems, spill absorbers, oil/water separators and the like.
- the invention further relates to liquid transport systems comprising said liquid transport members and articles utilizing these.
- the transport will happen from a liquid source through a liquid transport member to a liquid sink, for example from a reservoir through a pipe to another reservoir.
- a liquid source for example from a reservoir through a pipe to another reservoir.
- There can be differences in potential energy between the reservoirs such as hydrostatic height
- there can be frictional energy losses within the transport system such as within the transport member, in particular if the transport member is of significant length relative to the diameter thereof.
- liquid transport elements or members can be found in fields like water irrigation such as described in EP-A-0.439.890, or in the hygiene field, such as for absorbent articles like baby diapers both of the pull-on type or with fastening elements like tapes, training pants, adult incontinence products, feminine protection devices.
- capillary flow members such as fibrous materials like blotting paper, wherein the liquid can wick against the gravity.
- fibrous materials like blotting paper
- Such materials are limited in their flow and/or flux rates, especially when wicking height is added as an additional requirement.
- An improvement particularly towards high flux rates at wicking heights particularly useful for example for application in absorbent articles has been described in EP-A-0.810.078.
- capillary flow members can be non-fibrous, but yet porous structures, such as open celled foams.
- hydrophilic polymeric foams have been described, and especially hydrophilic open celled foams made by the so called High Internal Phase Emulsion (HIPE) polymerization process have been described in US-A-5.563.179 and US-A- 5.387.207.
- HIPE High Internal Phase Emulsion
- liquid transport members that can transport liquid against gravity at very high flux rates.
- liquid is not homogeneous in composition (such as a solution of salt in water), or in its phases (such as a liquid/solid suspension), it can be desired to transport the liquid in its totality, or only parts thereof.
- composition such as a solution of salt in water
- phases such as a liquid/solid suspension
- filtration technology exploits the higher and lower permeability of a member for one material or phase compared to another material or phase.
- filtration technology exploits the higher and lower permeability of a member for one material or phase compared to another material or phase.
- US-A-5.728.292 relates to non-woven fuel filter
- EP-A-0.773.058 relating to oleophilic filter structures.
- Such membranes are also disclosed to be used in absorbent systems.
- fluid absorbent materials can have osmotic effects, or can be gel- forming absorbent substances enclosed in semipermeable membranes, such as cellulose, regenerated cellulose, cellulose nitrate, cellulose acetate, cellulose acetate butyrate, polycarbonate, polyamide, fiberglass, polysulfone, of polytetrafluoroethylene, having pore sizes of between 0.001 ⁇ m and 20 ⁇ m, preferably between 0.005 ⁇ m and 8 ⁇ m, especially about 0.01 ⁇ m.
- the permeability of the membrane is intended to be such that the absorbed liquid can penetrate, but such that the absorbent material is retained.
- membranes having a high permeability K and a low thickness d so as to achieve a high liquid conductivity k/d of the layer, as being described herein after.
- promoters with higher molecular weight e.g., polyvinyl pyrrolidone with a molecular weight of 40,000
- the maximum pore size stated therein to be useful for this application is less than 0.5 ⁇ m, with pore sizes of about 0.01 ⁇ m or less being preferred.
- the exemplified materials allow the calculation of k/d values in the range of 3 to 7 * 10- 14 m.
- the absorbent body can further comprise for rapid discharge of fluids a liquid acquisition means, such as conventional acquisition means to provide interim storage of the fluids before these are slowly absorbed.
- a liquid acquisition means such as conventional acquisition means to provide interim storage of the fluids before these are slowly absorbed.
- an osmotic promoter namely a high-ionic strength material such as NaCl, or other high osmolality material like glucose or sucrose is placed inside a membrane such as made from cellulosic films.
- a membrane such as made from cellulosic films.
- fluid can enter the body through any part of the jacket, and no means is foreseen for liquid to leave the body.
- the promoter materials provide an osmotic driving force to pull the liquid through the membranes.
- the membranes are characterized by having a low permeability for the promoter, and the packets achieve typical rates of 0.001 ml/cm2/min.
- US-A-5.082.723 discloses an osmotic material like NaCl which is enclosed by superabsorbent material, such as a copolymer of acrylic acid and sodium acrylate, thereby aiming at improving absorbency, such as enhanced absorptive capacity on a "gram per gram” basis and absorption rate.
- a liquid transport member composed of at least two regions exhibiting a difference in permeability. It is a further object to provide liquid transport members exhibiting improved liquid transport, as expressed in significantly increased liquid flow rates, and especially liquid flux rates, i.e. the amount of liquid flowing in a time unit through a certain cross-section of the liquid transport member. It is a further object of the present invention to allow such liquid transport against gravity.
- the present invention is a liquid transport member having at least one bulk region with an average permeability k b , and a wall region that completely circumscribes said bulk region, whereby the wall region further comprises at least one port region having a thickness d and an average permeability k p throughout this thickness, whereby the bulk region has an average fluid permeability k b which is higher than the average fluid permeability k p of the port region and that said port region has a ratio of fluid permeability to thickness in the direction of fluid transport, k p /d p of at least 10 "7 m.
- the bulk region has a fluid permeability of at least 10 "11 m 2 , preferably at least 10 8 m 2 , more preferably at least 10 7 m 2 , most preferably at least 10 "5 m 2 , but preferably of not more than 10 2 m 2 .
- the said port region has a fluid permeability of at least 6*10 20 m 2 , preferably at least 7 * 10 18 m 2 , more preferably at least 3*10 14 m 2 , even more preferably of at least 1.2 * 10 " m 2 , or even at least 7*10 "11 m 2 , most preferably at least 10 *9 m 2 , or a ratio of fluid permeability to thickness in the direction of fluid transport, k p /d p of at least 5*10 "7 m, preferably at least 10 "6 m, preferably at least 10 5 m.
- the bulk region has an average dry density of more than 0.001 g/cm 3 .
- the liquid transport member comprises a first material in a first region, and wherein the member further comprises an additional element in contact with the first materials of the first region which extends into a neighbouring second region of said liquid transport member that is in contact with the wall region.
- the additional element can be in contact with the wall region and can extend into the neighbouring second region, and can have a capillary pressure for absorbing the liquid that is lower than the bubble point pressure of the liquid transport member.
- the additional element can comprise a softness layer.
- the ratio of permeability of the bulk region to the permeability of the port region of the liquid handling member is at least 10, preferably at least 100, more preferably at least 1000, and even more preferably at least 100,000.
- the liquid handling member can exhibit a bubble point pressure when measured with water having a surface tension of 72 mN/m of at least 1 kPa, preferably at least 2 kPa, more preferably at least 4.5 kPa, even more preferably 8 kPa, most preferably 50, and the port region of the member can exibit a a bubble point pressure when measured with water having a surface tension of 72 mN/m of at least 1 kPa, preferably at least 2 kPa, more preferably at least 4.5 kPa, even more preferably 8 kPa, most preferably 50 and when measured with an aqueous test solution having a surface tension of 33 mN/m of at least 0.67 kPa, preferably at least 1.3 kPa,
- a liquid transport member according to the present invention can loose more than 3% of the initial liquid when submitted to the closed system test.
- a liquid transport member can have a bulk region which has a larger average pore size than said port region, preferably such that the ratio of average pore size of the bulk region and the average pore size of the port region is at least 10, preferably at least 50, more preferably at least 100, and even more preferably at least 500, and most preferably at least 350, and the bulk region can have an average pore size of at least 200 ⁇ m, preferably at least 500 ⁇ m, more preferably of at least 1000 ⁇ m, and most preferably of at least 5000 ⁇ m, or a porosity of at least 50%, preferably at least 80%, more preferably at least 90%, even more preferably of at least 98%, and most preferably of at least 99%.
- the port region can have a porosity of at least 10%, preferably at least 20%, more preferably of at least 30%, and most preferably of at least 50%, or an average pore size of no more than 100 ⁇ m, preferably no more than 50 ⁇ m, more preferably of no more than 10 ⁇ m, and most preferably of no more than 5 ⁇ m, but preferably not less than 1 ⁇ m, preferably at least 3 ⁇ m.
- the port region can have an average thickness of no more than 100 ⁇ m, preferably no more than 50 ⁇ m, more preferably of no more than 10 ⁇ m, and most preferably of no more than 5 ⁇ m.
- the bulk region and the wall region can have a volume ratio of at least 10, preferably at least 100, more preferably at least 1000, and even more preferably at least 100,000.
- the port region is hydrophilic, preferably by having a receding contact angle for the liquid to be transported of less than 70 degrees, preferably less than 50 degrees, more preferably less than 20 degrees, and even more preferably less than 10 degrees.
- the port region does not reduce the surface tension of the transported liquid.
- the port region is oleophilic, preferably by having a receding contact angle for the liquid to be transported of less than 70 degrees, preferably less than 50 degrees, more preferably less than 20 degrees, and even more preferably less than 10 degrees.
- the liquid transport member or the bulk region thereof comprises a material which is expandable upon liquid contact and collapsible upon liquid removal, preferably by a volume expansion factor of at least 5.
- a liquid transport member according to the present invention can be sheetlike shape, or has a cylindrical like shape, or can have a cross-section area along the direction of liquid transport is not constant.
- the port region of the the member preferably have a larger area than the average cross-section of the member along the direction of liquid transport, preferably by at least a factor of 2, preferably a factor of 10, most preferably a factor of 100.
- the bulk region of a liquid transport member can comprise mate ⁇ al selected from the groups of fibers, particulates, foams, spirals, films, corrugated sheets, or tubes, and the wall region can comprise material selected from the groups of fibers, particulates, foams, spirals, films, corrugated sheets, tubes, woven webs.woven fiber meshes, apertured films, or monolithic films.
- the foam can be an pen cell reticulated foam, preferably selected from the group of cellulose sponge, polyurethane foam, HIPE foams, and the fibers can be made of polyolefins, polyesters, polyamids, polyethers, polyacrylics, polyurethanes, metal, glass, cellulose, cellulose derivatives.
- a liquid transport member can comprise a porous bulk region that is wrapped by a separate wall region. It also can comprise soluble materials, such as in the port region.
- the membranes in the port region can comprise stimulus activatable membrane materials, such as a membrane, which changes its hydrophilicity upon a temperature change.
- the liquid transport member can be initially partially or essentially filled with liquid., or it can be initially under vacuum.
- the liquid transport member is suitable for the transport of water-based liquids or of viscoelastic liquids, of bodily discharge fluids, as urine, blood menses, sweat or feces, or of oil, grease, or other non-water based liquids.
- Such a transport can be also selective, such as for oil or grease, but not water based liquids.
- a liquid transport can exhibit properties or parameter which are established prior to or at the liquid handling, preferably by activation by contact with the liquid, pH, temperature, enzymes, chemical reaction, salt concentration or mechanical activation.
- the present invention relates to a liquid transport system having a liquid transport member as described in the above, in addition to a source or sink of liquid, each of the sink or source possibly being outside or inside of the member.
- a system can exhibit an absorbent capacity of at least 5g/g, preferably at least 10g/g, more preferably at least 50g/g on the basis of the weight of the said system, when submitted to the Demand Absorbency Test.
- Such a system can comprise materials in the sink, which have an absorption capacity in the teabag test of at least 10 g/g, preferably at least 20 g/g and more preferably at least 50 g/g on the basis of the weight of the sink material.
- the sink material can also exhibit an absorbent capacity of at least 5 g/g, preferably of at least 10 g/g, more preferably of at least 50 g/g on the basis of the weight of the sink material, when measured in the Capillary Sorption Test at a pressure up to the bubble point pressure of the port region, and which has an absorbent capacity of at less than 5 g/g, preferably of less than 2 g/g, more preferably of less than 1 g/g and most preferably of less than 0.2g/g, when measured in the Capilalry Soprtion Test at a pressure exceeding the bubble point pressure of the port region.
- a system can comprise superabsorbent material or open celled foam of the High Internal Phase Emulsion (HIPE) type.
- the invention is concerned with an article including a liquid transport member or system.
- a liquid transport member or system can be a baby or adult incontinence diaper, a feminine protection pad, a pantiliner, or a training pant, or a grease absorber, or a water transport member.
- the present invention is concerned with the method of making a liquid transport member, comprising the steps of a) providing a bulk region material or a void space; b) providing a wall material comprising a port region; c) completely enclosing said bulk region material or said void space by said wall material; d) providing a transport enablement means selected from d1) vacuum; d2) partial or essentially complete liquid filling; d3) expandable elastics / springs.
- the method can further comprise the step of applying activation means, such as e1) a liquid dissolving port region; e2) a liquid dissolving expandable elastication / springs; e3) a removable release element; or e4) a removable sealing packaging.
- the method can comprise the steps of a) wrapping a highly porous bulk mate ⁇ al with a separate wall mate ⁇ al that comprises at least one permeable port region, b) completely sealing the wall region, and c) evacuating the member essentially of air, optionally filling the member with liquid.
- FIG. 1 Schematic diagram of conventional open siphon.
- Fig. 2 Schematic diagram of a liquid transport member according to the present invention.
- Fig. 3 A, B Conventional Siphon system, and liquid transport member according to the present invention.
- Fig. 4 Schematic cross-sectional view through a liquid transport member.
- Fig. 5 A, B, C Schematic representation for the determination of port region thickness.
- Fig. 6 Correlation of permeability and bubble point pressure.
- Fig. 7 to 12 Schematic diagrams of various embodiments of liquid transport member according to the present invention.
- Fig. 13 A, B, C Liquid Transport Systems according to the present invention.
- Fig. 14 Schematic diagram of an absorbent article.
- Fig. 15 to 16 A, B Absorbent Article comprising a liquid transport member.
- Fig. 17 A to 18 A, B Specific embodiments of liquid transport member.
- Fig. 19 to 20 A, B Liquid permeability test.
- Fig. 21 A - D Capillary abso ⁇ tion test.
- a “liquid transport member” refers to a material or a composite of materials, which is able to transport liquids. Such a member contains at least two regions, an “inner” region, for which the term “bulk” region can be used interchangeably, and a wall region comprising at least one "port” region.
- the terms “inner” and “outer” refer to the relative positioning of the regions, namely meaning, that the outer region generally circumscribes the inner region, such as a wall region circumscribing a bulk region
- the term “Z-dimension” refers to the dimension orthogonal to the length and width of the liquid transport member or article. The Z-dimension usually corresponds to the thickness of the liquid transport member or the article.
- the term "X-Y dimension" refers to the plane orthogonal to the thickness of the member, or article.
- the X-Y dimension usually corresponds to the length and width, respectively, of the liquid transport member, or article.
- the term layer also can apply to a member, which - when describing it in spherical or cylindrical co-ordinates - extends in radial direction much less than in the other ones.
- the skin of a balloon would be considered a layer in this context, whereby the skin would define the wall region, and the air filled center part the inner region.
- the term “layer” refers to a region whose primary dimension is X-Y, i.e., along its length and width. It should be understood that the term layer is not necessarily limited to single layers or sheets of material. Thus the layer can comprise laminates or combinations of several sheets or webs of the requisite type of materials. Accordingly, the term “layer” includes the terms “layers” and "layered”.
- upper refers to members, articles such as layers, that are positioned upwardly (i.e. oriented against the gravity vector) during the intended use.
- a liquid transport member intended to transport liquid from a "lower” reservoir to an “upper” one, this is meant to be transport against gravity.
- absorbent articles refers to devices which absorb and contain body exudates, and, more specifically, refers to devices which are placed against or in proximity to the body of the wearer to absorb and contain the various exudates discharged from the body.
- body fluids includes, but is not limited to, urine, menses and vaginal discharges, sweat and feces.
- absorbent articles which are not intended to be laundered or otherwise restored or reused as an absorbent article (i.e., they are intended to be discarded after use and, preferably, to be recycled, composted or otherwise disposed of in an environmentally compatible manner).
- absorbent core refers to the component of the absorbent article that is primarily responsible for fluid handling properties of the article, including acquiring, transporting, distributing and storing body fluids. As such, the absorbent core typically does not include the topsheet or backsheet of the absorbent article.
- a member or material can be described by having a certain structure, such as a porosity, which is defined by the ratio of the volume of the solid matter of the member or material to the total volume of the member or material.
- a porosity can be calculated from the specific weight (density) of the structure, the caliper and the specific weight (density) of the polypropylene fiber:
- activatable refers to the situation, where a certain ability is restricted by a certain means, such that upon release of this means a reaction such as a mechanical response happens. For example, if a spring is held together by a clamp (and thus would be activatable), releasing of the clamp results in activating the expansion of the spring.
- the expansion can be defined by the elastic modulus , as well known in the art. Basic principles and definitions Liquid transport mechanism in conventional capillary flow systems
- the liquid In materials, for which the liquid transport is based on capillary pressure as the driving force, the liquid is pulled into the pores that were initially dry by the interaction of the liquid with the surface of the pores. Filling the pores with liquid replaces the air in these pores. If such a material is at least partially saturated and if further a hydrostatic, capillary, or osmotic suction force is applied to at least one region of that material, liquid will be desorbed from this material if the suction pressure is larger than the capillary pressure that retains the liquid in the pores of the materials (refer e.g., to "Dynamics of fluids in porous media" by J. Bear, Haifa, publ. Dover Publications Inc., NY, 1988).
- a conventional capillary flow material is connected at one end to a liquid source (e.g., a reservoir) and on the other end to a liquid sink (e.g., a hydrostatic suction), the liquid transport through this material is based on the absorption / desorption and re-absorption cycle of the individual pores with the capillary force at the liquid / air-interface providing the internal driving force for the liquid through the material.
- a liquid source e.g., a reservoir
- a liquid sink e.g., a hydrostatic suction
- a simplifying explanation for the functioning of the present invention can start with comparing it to a siphon (refer to Fig. 1), well known from drainage systems as a tubing in form of a laying "S" (101).
- the principle thereof is, that - once the tubing (102) is filled with liquid (103) - upon receipt of further liquid (as indicated by 106) - entering the siphon at one end, almost immediately liquid leaves the siphon at the other end (as indicated by 107), as - because the siphon is being filled with incompressible liquid - the entering liquid is immediately displacing liquid in the siphon forcing the liquid at the other end to exit the siphon, if there is a pressure difference for the liquid between the point of entry and the point of exit of said siphon.
- liquid is entering and leaving the system through an open surface inlet and outlet "port regions" (104 and 105 respectively).
- the driving pressure to move liquid along the siphon can be obtained via a variety of mechanisms. For example, if the inlet is at a higher position than the outlet, gravity will generate a hydrostatic pressure difference generating liquid flow through the system.
- the outlet port is higher than the inlet port, and the liquid has to be transported against gravity, the liquid will flow through this siphon only if an external pressure difference larger than hydrostatic pressure difference is applied.
- a pump could generate enough suction or pressure to move liquid through this siphon.
- liquid flow through a siphon or pipe is caused by an overall pressure difference between its inlet and outlet port region. This can be described by well known models, such as expressed in the Bernoulli equation.
- the liquid transport member (201) does not need to be s-shaped, but can be a straight tube (202).
- the liquid transport member can be filled with liquid (203), if the inlet and outlet of the transport member are covered by inlet port materials (204) and outlet port materials (205).
- inlet port materials (204) and outlet port materials (205) Upon receipt of additional liquid (indicated by 206) which readily penetrates through the inlet port material (204), liquid (207) will immediately leave the member through the outlet region (205), via the outlet port material.
- the inlet and/or outlet ports are not open surfaces, but have special permeability requirements as explained in more detail hereinafter, which prevent air or gas from penetrating into the transport member, thus the transport member remains filled with liquid.
- a liquid transport member according to the present invention can be combined with one or more liquid source(s) and/or sink(s) to form a liquid transport system.
- Such liquid sources or sinks can be attached to the transport member such as at inlet and/or outlet regions or the sink or the source can be integral with the member.
- a liquid sink can be - for example - integral with the transport member, when the transport member can expand its volume thereby receiving the transported liquid.
- Transport System can be seen in Fig. 3 A (siphon) and 3B (present invention).
- a liquid (source) reservoir (301) with a lower (in the direction of gravity) liquid (sink) reservoir (302) by a conventional tube or pipe with open ends (303) in the shape on an inverted “U” (or "J")
- liquid can flow from the upper to the lower reservoir only if the tube is kept full with liquid by having the upper end immersed in liquid. If air can enter the pipe such as by removing the upper end (305) from the liquid, the transport will be interrupted, and the tube must be refilled to be functional again.
- a liquid transport member according to the present invention would look very similar in an analog arrangement, except for the ends of the transport member, inlet (305) and outlet port (306), comprising inlet and outlet port materials with special permeability requirements as explained in more detail hereinafter instead of open areas.
- the inlet and outlet materials prevent air or gas from penetrating into the transport member, and thereby maintain the liquid transport capability even if the inlet is not immersed into the liquid source reservoir. If the transport member is not immersed into the liquid source reservoir, liquid transport will obviously stop, but can commence immediately upon re-immersion.
- the present invention is concerned with liquid transport, which is based upon direct suction rather than on capillarity.
- the liquid is transported through a region through which substantially no air (or other gas) should enter this member (or at least not in a significant amount).
- the driving force for liquid flowing through such a member can be created by a liquid sink and liquid source in liquid communication with the member, either externally, or internally.
- liquid refers to fluids consisting of a continuous liquid phase, optionally comprising a discontinuous phase such as an immiscible liquid phase, or solid or gases, so as to form suspension, emulsions or the like.
- the liquid can be homogeneous in composition, it can be a mixture of miscible liquids, it can be a solution of solids or gases in a liquid, and the like.
- Non-limiting examples for liquids that can be transported through members according to the present invention include water, pure or with additives or contaminants, salt solutions, urine, blood, menstrual fluids, fecal material over a wide ranged of consistencies and viscosities, oil, food grease, lotions, creams, and the like.
- transport liquid refers to the liquid which is actually transported by the transport member, i.e., this can be the total of a homogeneous phase, or it can be the solvent in a phase comprising dissolved matter, e.g., the water of a aqueous salt solution, or it can be one phase in a multiphase liquid, or it can be that the total of the multicomponent or multiphase liquid.
- liquid the respective liquid properties e.g., the surface energy, viscosity, density, etc., are relevant for various embodiments.
- the liquid entering the liquid transport member will be the same or of the same type as the liquid leaving the member or being stored therein, this does not necessarily need to be the case.
- the aqueous phase may leave the member first.
- the aqueous phase could be considered "replaceable liquid".
- a liquid transport member in the sense of the present invention has to comprise at least two regions - a "bulk region” and a "wall region” comprising at least one liquid permeable "port region".
- the geometry, and especially the requirement of the wall region completely circumscribing the bulk region is defined by the following description (refer to Fig.4), which considers a transport member at one point in time.
- the bulk / inner regions (403) and the wall region (404) are distinctively different and non-overlapping geometric regions with regard to each other as well as with regard to the outside region (i.e. "the rest of the universe"), that can be defined by the following characterization (refer to Fig.4): Thus, any point can only belong to one of the regions.
- the bulk region (403) is connected, i.e. for any two points A' and A" inside the bulk region (403), there is at least one continuous (curved or straight) line connecting the two points without leaving the bulk region (403).
- a straight ray has the geometrical meaning of a cylinder of infinite length in analogy to point A being a light source, and the rays being rays of light, however, these rays need to have a minimum geometrical "thickness" (as otherwise a line can pass through the pore opening of the port regions (405)).
- This geometrical thickness is set at 2 mm - which of course has to be considered in an approximation in the proximity of the point A (not having a three-dimensional extension to be matched with such a rodlike ray).
- the wall region (404) completely circumscribes the bulk region (403). Thus, for any points A" - belonging to the bulk region (403) - and C - belonging to the outer region - any continuous curved rod (in analogy to a continuous curved line but having circular thickness of 2 mm diameter), intersects the wall region (404).
- a port region (405) connects a bulk region (403) with the outside region, and there exists at least one continuous curved rod connecting any point A from the bulk regions with any point C from the outside region having a circular thickness of 2mm, that intersects the port region (405).
- region refers to three-dimensional regions, which can be of any shape. Often, but not necessarily, the thickness of the region can be thin, such that the region appears like a flat structure, such as a thin film.
- membranes can be employed in a film form, which - depending on the porosity - can have thickness of 100 ⁇ m or much less, thus being much smaller than the extension of the membrane perpendicular thereto (i.e. length and width dimension).
- a wall region may be arranged around a bulk region for example in an overlapping arrangement, i.e. that certain parts of the wall region material contact each other and are connected to each other such as by sealing. Then, this sealing should have no openings which are sufficiently large to interrupt the functionality of the member, i.e. the sealing line could be considered to belong either to an (impermeable) wall region, or a wall region.
- regions Whilst a region can be described by having at least one property to remain within certain limits so as to define the common functionality of the subregions of this region, other properties may well change within this sub-regions.
- regions should be read to also encompass the term “region”, i.e. if a member comprises certain "regions", the possibility of comprising only one such region should be included in this term, unless otherwise explicitly mentioned.
- the "port” and “bulk / inner” regions can be readily distinguished from one another, such as a void space for one region and a membrane for another, or these regions can have a gradual transition with respect to certain relevant parameters as will be described hereinafter.
- a transport member according to the present invention has at least one region satisfying the requirements for the "inner region” and one region satisfying the requirements for the wall region", (which in fact can have an very small thickness relative to its extension in the other two dimensions, and thus appear more as a surface than a volume).
- the wall region comprises at least a port region, which may comprise further regions, in particular inlet and / or outlet region.
- the transport path can be defined as the path of a liquid entering a port region and the liquid exiting a port region, whereby the liquid transport path runs through the bulk region.
- the transport path can also be defined by the path of a liquid entering a port region and then entering a fluid storage region which is integral within the inner region of the transport member, or alternatively defined as the path of a liquid from a liquid releasing source region within the inner region of the transport member to an outlet port region.
- the transport path of an liquid transport member can be of substantial length, a length of 100 m or even more can be contemplated, alternatively, the liquid transport member can also be of quite short length, such as a few millimeters or even less. Whilst it is a particular benefit of the present invention to provide high transport rates and also enable large amounts of liquid to be transported, the latter is not a requirement. It can also be contemplated, that only small amounts of liquid are transported over relatively short times, for example when the system is used to transmit signals in the form of liquids in order to trigger a certain response to the signal at an alternative point along the transport member.
- the liquid transport member may function as a real-time signaling device.
- the transported liquid may perform a function at the outlet port, such as activating a void to release mechanical energy and create a three-dimensional structure.
- the liquid transport member may deliver a triggering signal to a responsive device comprising a compressed material that is held in vacuum compression within a bag, at least a portion of which is soluble (e.g., in water).
- a threshold level of the signaling liquid (e.g., water) delivered by the liquid transport member dissolves a portion of the water soluble region and discontinuously releases the vacuum, the compressed material expands to form a three dimensional structure.
- the compressed material may be a resilient plastic foam that has a shaped void of sufficient volume to capture bodily waste.
- the compressed material may be an absorbent material that functions as a pump by drawing fluid into its body as it expands (e.g., may function as a liquid sink as described below).
- the liquid transport can take place along a single transport path or along multiple paths, which can split or re-combine across the transport member.
- the transport path will define a transport direction, allowing definition of the transport cross sectional plane which is perpendicular to said path.
- the inner / bulk region configuration will then define the transport cross sectional area, combining the various transport paths.
- a certain region can consist of one homogeneous material, or a region can comprise such a homogeneous material.
- a material can have varying properties and/ or parameters, and thus comprise more than one region. The following description will focus on describing the properties and parameters for the functionally defined regions.
- the present invention is concerned with a liquid transport member, which is based upon direct suction rather than on capillarity.
- the liquid is transported through a region into which substantially no air (or other gas) should enter (at all or at least not in a significant amount).
- the driving force for liquid flowing through such a member can be created by a liquid sink and/or liquid source in liquid communication with the transport member, either externally, or internally.
- the direct suction is maintained by ensuring that substantially no air or gas enters the liquid transport member during transport. This means, that the wall regions including the port regions should be substantially air impermeable up to a certain pressure, namely the bubble point pressure as will be discussed in more detail.
- a liquid transport member must have a certain liquid permeability (as described hereinafter).
- a higher liquid permeability provides less flow resistance, and thus is preferred from this point of view.
- liquid transport member should be substantially impermeable for air or gas during the liquid transport.
- liquid transport is generally controlled by the interaction of pore size and permeability, such that open, highly permeable structures will generally be comprised of relatively large pores. These large pores provide highly permeable structures, however these structures have very limited wicking heights for a given set of respective surface energies, i.e., a given combination of type of material and liquids. Pore size can also affect liquid retention under normal use conditions.
- the liquid transport member has an inner region with a liquid permeability which is relatively high to provide maximum liquid transport rate.
- the permeability of a port region which can be a part of the wall region circumscribing the bulk region, is substantially less. This is achieved by port regions having a membrane functionality, designed for the intended use conditions. The membrane is permeable to liquids, but not to gases or vapors.
- Such a property is generally expressed by the bubble point pressure parameter, which is - in short - defined by the pressure up to which gas or air does not penetrate through a wetted membrane.
- the property requirements have to be fulfilled at the time of liquid transport. It can be, however, that these are created or adjusted by activating a transport member, e.g., prior to usage, which - without or prior to such activation - would not satisfy the requirements but does so after activation.
- a member can be elastically compressed or collapsed, and expand upon wetting to then create a structure with the required properties.
- capillary flow transport is dominated by surface energy effects mechanisms and pore structure, which is determined by number of pores, as well as the shape, size, and also pore size distribution.
- liquid is removed at one end of a capillary system such as by a suction means, this liquid is desorbed out of the capillaries closest to this suction device, which are then at least partially filled by air, and which are then refilled through capillary pressure by liquid from adjacent capillaries, which are then filled by liquid from following adjacent capillaries and so on.
- liquid transport through a conventional capillary flow structure is based upon absorption - desorption and re-absorption cycle of the individual pores.
- the flow respectively flux is determined by the average permeability along the pathway and by the suction at the end of the transport path.
- Such a local suction will generally also be dependent on the local saturation of the material, i.e. if the suction device is able to reduce the saturation of the region close to it, the flow/flux will be higher.
- a specific idealized execution of such porous liquid transport members are so-called “capillary tubes”, which can be described as parallel pipes with the inner tube diameter and wall thickness defining the overall openness (or porosity) of the system.
- Such systems will have a relative large flux against a certain height if these are "mono-porous", i.e., if the pores have the same, optimal pore size. Then the flow is determined by the pore structure, the surface energy relation, and the cross-sectional area of the porous system, and can be estimated by well know approximations.
- Realistic porous structures such as fibrous or foam type structures, will not transport like the ideal structures of capillary tubes.
- Realistic porous structures have pores that are not aligned, i.e. not straight, as the capillary tubes and the pore sizes are also non-uniform. Both of these effects often reduce the transport efficiency of such capillary systems.
- the transport member with different pore sizes there are at least two regions within the transport member with different pore sizes, namely the one or more port region(s) having smaller pore sizes (which in conventional systems would result in very low flow rates) and the inner region having a substantially larger pore sizes (which in conventional systems would result in very low achievable transport heights).
- the overall flow and transport height through the transport member are synergistically improved by the high permeability of the inner region (which therefore can be relatively long whilst having small cross-sectional areas), and by the relatively high bubble point pressure of the port regions (which can have sufficiently large surfaces, and/ or small thickness).
- the high bubble point pressure of the port regions is obtained by the capillary pressure of the small pores of said port region, which will - once wetted - prevent air or gas from entering the transport member.
- the present invention is concerned with liquid transport members, which - once activated, and/or wetted - are selective with regards to the fluids they transport.
- the port regions of the transport member are - up to a certain limit as can be expressed by the bubble point pressure - closed for the ambient gas (like air), but relatively open for the transport liquid (like water).
- the port regions do not require a specific directionality of their properties, i.e. the materials used therein can be used in either orientation of liquid flow there through.
- the membranes it a requirement for the membranes to have different properties (such as permeability) with regard to certain parts or components of the liquid. This is in contrast to the membranes such as described for osmotic absorbent packets in US-A-5.108.383 (White et al.), where the membranes have to have a low permeability for the promoter material, such a salt, respectively salt-ions.
- a key requirement for the bulk region is to have a low average flow resistance, such as expressed by having a permeability k of at least 10 "11 m 2 , preferably more than 10 "8 m 2 , more preferably more than 10 "7 m 2 , and most preferably more than 10 "5 m 2 .
- the bulk region may actually be a void which is circumscribed, and thusly defined by the wall regions as described hereinafter, but for particular applications it can be desirable that the bulk region is made of a open porous material, thus exhibiting a certain "dry density" (as being defined as the density of the material excluding the fluid contained in the pores), and a certain maximum permeability in the inner regions, such as no more then 10 2 m 2 .
- dry density as being defined as the density of the material excluding the fluid contained in the pores
- a certain maximum permeability in the inner regions such as no more then 10 2 m 2 .
- One important means to achieve high permeabilities for the inner regions can be achieved by utilizing material providing relatively high porosity.
- Such a porosity which is commonly defined as the ratio of the volume of the materials that makes up the porous materials to the total volume of the porous materials, and as determined via density measurements commonly known, should be at least 50%, preferably at least 80%, more preferably at least 90%, or even exceeding 98%, or 99%.
- the porosity approaches or even reaches 100%.
- Materials suitable for the inner region can have a non-zero dry density, but not exceeding 0.30 g/m 2 , preferably less than 0.2 g/m 2 , or more preferably less than 0.1 g/m 2 , or even less than 0.05 g/m 2 .
- the inner region can have pores, which are larger than about 200 ⁇ m, 500 ⁇ m, 1 mm or even 9 mm in diameter or more.
- the inner region can have pores as large as 10 cm.
- Such pores may be smaller prior to the fluid transport, such that the inner region may have a smaller volume, and expand just prior or at the liquid contact.
- a volumetric expansion factor of at least 5, preferably more than 10.
- Such an expansion can be achieved by materials having an elastic modulus of more than the external pressure which, however, must be smaller than the bubble point pressure.
- High porosities can be achieved by a number of materials, well known in the art as such.
- fibrous members can readily achieve such porosity values.
- Non-limiting examples for such fibrous materials that can be comprised in the bulk region are high-loft non-wovens, e.g., made from polyolefin or polyester fibers as used in the hygienic article field, or car industry, or for upholstery or
- HVAC industry Other examples comprise fiber webs made from cellulosic fibers.
- Such porosities can further be achieved by porous, open celled foam structures, such as - without intending any limitation - for example pulyurethane reticulated foams, cellulose sponges, or open cell foams as made by the High Internal Phase Emulsion Polymerization process (HIPE foams), all well known from a variety of industrial applications such as filtering technology, upholstery, hygiene and so on.
- HIPE foams High Internal Phase Emulsion Polymerization process
- Such porosities can be achieved by wall regions (such as explained in more detail hereinafter) which circumscribe voids defining the inner region, such as exemplified by pipes. Alternatively, several smaller pipes can be bundled.
- Such porosities can further be achieved by "space holders", such as springs, spacer, particulate material, corrugated structures and the like.
- space holders such as springs, spacer, particulate material, corrugated structures and the like.
- the inner region pore sizes or permeabilities can be homogeneous throughout the inner region, or can be inhomogeneous.
- the high porosity of the inner region is maintained throughout all stages between manufacture and use of the liquid transport member, but the voids within the inner region can be created shortly before or during its intended use.
- bellow like structures held together by suitable means can be activated by a user, and during its expansion, the liquid penetrates through a port region into the expanding inner region, thereby filling the transport member completely or at least sufficiently to not hinder the liquid flow.
- open celled foam materials such as described in (US-A- 5.563.179 or US-A-5.387.207) have the tendency to collapse upon removal of water, and the ability to re-expand upon re-wetting.
- foams can be transported from the manufacturing site to the user in a relatively dry, and hence thin (or low-volume), and only upon contact with the source liquid increase their volume so as to satisfy the void permeability requirements.
- the inner regions can have various forms or shapes.
- the inner region can be cylindrical, ellipsoidal, sheet like, stripe like, or can have any irregular shape.
- the inner regions can have constant cross-sectional area, with constant or varying cross-sectional shape, like rectangular, triangular, circular, elliptical, or irregular.
- a cross-sectional area is defined for the use herein as a cross-section of the inner region, prior to addition of source liquid, when measured in the plane perpendicular to the flow path of the transport liquid, and this definition will be used to determine the average inner region cross-sectional area by averaging the individual cross-sectional areas all over the flow path(s).
- the absolute size of the inner region should be selected to suitably match the geometric requirements of the intended use. Generally, it will be desirable to have the minimum dimension for the intended use. A benefit of the designs according to the present invention is to allow much smaller cross-sectional areas than conventional materials.
- the dimensions of the inner region are determined by the permeability of said inner region, which can be very high, due to possible large pores, as the inner region does not have to be designed under the contradicting requirements of high flux (i.e. large pores) and high vertical liquid transport (i.e. small pores). Such large pemeabilities allow much smaller cross- sections, and hence very different designs.
- the length of the inner region can be significantly larger than for conventional systems, as also with regard to this parameter the novel transport member can bridge longer distances and also greater vertical liquid transport heights.
- the inner region can be essentially non-deformable, i.e. maintains its shape, form, volume under the normal conditions of the intended use. However, in many uses, it will be desirable, that the inner region allows the complete member to remain soft and pliable.
- the inner region can change its shape, such as under deforming forces or pressures during use, or under the influence of the fluid itself.
- the deformability or absence thereof can be achieved by selection of one or more materials in the inner region (such as a fibrous member), or can be essentially determined by the circumscribing regions, such as by the wall regions of the transport member.
- One such approach is to utilize elastomeric materials as the wall material.
- the voids of the inner region can be confined by wall regions only, or the inner region can comprise internal separations therein.
- the inner region is made up of parallel pipes, with impermeable cylindrical walls, these would be considered to be such internal separations, thereby possibly creating pores which are unitary with the inner, hollow opening of the pipes, and possibly other pores created by the interstitial spaces between the pipes.
- the inner region comprises a fibrous structure
- the fiber material can be considered to form such internal separations.
- the internal separations of the inner region can have surface energies adapted to the transported liquid. For example, in order to ease wetting and/or transport of aqueous liquids, the separations or parts thereof can be hydrophilic.
- the separations of the inner regions it is preferred to have the separations of the inner regions to be wettable by such liquids, and even more preferred to have adhesion tensions of more than 65 mN/m, more preferably more than 70mN/m.
- the separations or parts thereof can be oleo- or lipophilic.
- the confining separations of the inner region may further comprise materials which significantly change their properties upon wetting, or which even may dissolve upon wetting.
- the inner region may comprise an open cell foam material having a relatively small pore at least partially being made of soluble material, such as polyvinylalcohol or the like. The small porosity can draw in liquid at the initial phase of liquid transport, and then rapidly dissolve so as to then leave large voids filled with liquid. Alternatively, such materials may fill larger pores, completely or partially,
- the inner region can comprise soluble materials, such as poly(vinyl) alcohol or poly(vinyl) acetate. Such materials can fill the voids, or support a collapsed state of the voids before the member is contacted with liquid. Upon contact with fluid, such as water, these materials may dissolve and thereby create empty or expanded voids.
- soluble materials such as poly(vinyl) alcohol or poly(vinyl) acetate.
- Such materials can fill the voids, or support a collapsed state of the voids before the member is contacted with liquid. Upon contact with fluid, such as water, these materials may dissolve and thereby create empty or expanded voids.
- the voids of the inner region are essentially completely filled with an essentially incompressible fluid.
- most of the void volume preferably more than 90%, more preferably more than 95%, and even more preferably more than 99%, including 100%, is filled with the liquid.
- the inner region can be designed so as to enhance accumulation of gas or other liquid in parts of the region where it is less detrimental.
- the remainder of the voids can then be filled with other fluid, such as residual gas or vapors, or immiscible liquid like oil in an inner region filled with aqueous liquids, or can be solids, like particulates, fibers, films.
- the liquid comprised in the inner region can be of the same type as the liquid being intended to be transported.
- the inner region of the transport member can be filled with water - or if oil is the intended transport liquid, the inner region can be filled with oil.
- the liquid in the inner region can also be different - whereby these differences can be relatively small in nature (such as when the intended transport liquid is water, the inner region liquid can be an aqueous solution, and vice versa).
- the intended transport liquid can be quite different in its properties, when compared to the liquid which has been pre-filled into the inner region, such as when the source liquid is oil, which is transported through a pipe initially filled with water and closed by suitable inlet and outlet ports, whereby the water leaves the member by a suitable outlet port region, and the oil enters the member by a suitable inlet port region.
- the total amount of transported liquid is limited by the amount which can be received within the member respectively the amount of liquid exchanged, unless there were, for example, outlet port regions comprising materials with properties compatible with the liquids so as to allow functionality with one or both of the liquids.
- the liquid of the inner region and the liquid to be transported can be mutually soluble, such as salt solutions in water.
- the inner region can be filled with water.
- the inner region comprises a vacuum, or a gas or vapor below the corresponding equilibrium, ambient or external, pressure at the respective temperatures, and volumetric conditions.
- the liquid can enter into the inner region by the permeable port regions (as described hereinafter), and then fill the voids of the inner region to the required degree. Thereafter, the now filled inner region functions like a "pre- filled" region as described in the above.
- a simple and yet very descriptive example for an inner region is an empty tube defined by impermeable or semi-permeable walls, as already discussed and depicted in Fig. 2.
- the diameter of such tubes can be relatively large compared to diameters commonly used for transport in capillary systems. The diameter of course depends highly on the specific system and intended use.
- pore sizes of 2 - 9 mm or more have been found to function satisfactorily.
- Pieces of glass tubes can provide the right functionality, however, for certain applications such structures may have some mechanical strength constraints.
- Suitable tubes can also be made of silicon, rubber, PVC, etc., e.g., Masterflex 6404-17 by Norton, distributed by the Barnant
- Filtren (Filtren TM10 blue, Filtren TM20 blue, Filtren TM30 blue, Filtren Firend 10 black, Filtren Firend 30 black, Filtren HC 20 grey, Filtren Firend HC 30 grex,
- a further embodiment to exemplify a material with two pore size regions can be seen in PCT application US97/20840, relating to a woven loop structure.
- the inner region may comprise absorbent materials, such as super absorbent gelling materials or other materials as described for being suitable as a liquid sink material herein after.
- the promoter materials of Membrane Osmotic packets, (MOP) such as disclosed in US-A-5.082.723 (White, Allied Signals) can be suitable for being used in the inner region.
- MOP Membrane Osmotic packets,
- the inner region may further be constructed form several materials, i.e. for example from combinations of the above.
- the inner region may also comprise stripes, particulates, or other in- homogeneous structures generating large voids between themselves and acting as space holders. As will be described in more details for the port regions, the fluids in the inner region must not prevent the port regions from being filled with the transport liquid.
- the degree of vacuum for example, or the degree of miscibility or immiscibility must not be such that liquids from the port region are drawn into the inner region without the port region(s) being refilled with transport liquid.
- the liquid transport member according to the present invention comprises in addition to the inner regions a wall region circumscribing this inner region in the geometric definition as described hereinbefore.
- This wall region must comprise at least one port region, as described hereinafter.
- the wall region can further comprise materials, which are essentially impermeable to liquids and/or gases, thereby not interfering with the liquid handling functionality of the port regions, and also preventing ambient gases or vapors from penetrating into the liquid transport member.
- Such walls can be of any structure or shape, and can re present the key structural element of the liquid transport member.
- Such walls can be in the shape of a straight or bent pipe, of a flexible pipe, or of cubical shape and so on.
- the walls can be thin, flexible films, circumscribing the inner region.
- Such walls can be expandable, either permanently via deformation or elastically via an elastomeric film, or upon activation.
- wall regions as such are an essential element for the present invention, this is particularly true for the port region comprised in such wallregions, and described in the following.
- the properties of the remaining parts of the wall regions can be important for the overall structure, for resilience, and other structural effects.
- the port regions can generally be described to comprise materials which have different permeabilities for different fluids, namely they should be permeable for the transport liquid, but not for the ambient gas (like air), under ⁇ otherwise same conditions (like temperature, or pressure, ...) and once they are wetted with /filled with the transport liquid or similarly functioning liquid.
- a membrane is generally defined as a region, that is permeable for liquid, gas or a suspension of particles in a liquid or gas.
- the membrane may for example comprise a microporous region to provide liquid permeability through the capillaries.
- the membrane may comprise a monolithic region comprising a block-copolymer through which the liquid is transported via diffusion.
- membranes will often have selective transport properties for liquids, gases or suspensions depending on the type of medium to be transported. They are therefore widely used in filtration of fine particles out of suspensions (e.g. in liquid filtration, air filtration).
- Other type of membranes show selective transport for different type of ions or molecules and are therefore found in biological systems (e.g. cell membranes, molecular sieves) or in chemical engineering applications (e.g. for reverse osmosis).
- Microporous hydrophobic membranes will typically allow gas to permeate, while water-based liquids will not be transported through the membrane if the driving pressure is below a threshold pressure commonly referred to as
- hydrophilic microporous membranes will transport water based liquids. Once wetted, however, gases (e.g. air) will essentially not pass through the membrane if the driving pressure is below a threshold pressure commonly referred to as "bubble point pressure",
- Hydrophilic monolithic films will typically allow water vapor to permeate, while gas will not be transported rapidly through the membrane.
- membranes can also be used for non-water based liquids such as oils.
- most hydrophobic materials will be in fact oleophilic.
- a hydrophobic microporous membrane will therefore be permeable for oil but not for water and can be used to transport oil, or also separate oil and water.
- Membranes are often produced as thin sheets, and they can be used alone or in combination with a support layer (e.g. a nonwoven) or in a support element
- membranes include but are not limited to polymeric thin layers directly coated onto another material, bags, corrugated sheets.
- membranes are "activatable” or “switchable” membranes that can change their properties after activation or in response to a stimulus. This change in properties might be permanent or reversible depending on the specific use.
- a hydrophobic microporous layer may be coated with a thin dissolvable layer e.g. made from poly(vinyl)alcohol.
- a double layer system will be impermeable to gas.
- the poly(vinyl)alcohol film has been dissolved, the system will be permeable for gas but still impermeable for aqueous liquids.
- a hydrophilic membrane is coated by such a soluble layer, it might become activated upon liquid contact to allow liquid to pass through, but not air.
- a hydrophilic microporous membrane is initially dry. In this state the membrane is permeable for air. Once wetted with water, the membrane is no longer air permeable.
- a microporous membrane coated with a surfactant that changes its hydrophilicity depending on temperature. For example the membrane will then be hydrophilic for warm liquid and hydrophobic for cold liquid. As a result, warm liquid will pass through the membrane while cold liquid will not.
- Other examples include but are not limited to microporous membranes made from an stimulus activated gel that changes its dimensions in response to pH, temperature, electrical fields, radiation or the like.
- the port regions can be described by a number of properties and parameters.
- a key aspect of the port region is the permeability.
- a volumetric flow dV/dt through the membrane is caused by an external pressure difference ⁇ p (driving pressure), and the permeability function k may depend on the type of medium to be transported (e.g. liquid or gas), a threshold pressure, and a stimulus or activation. Further relevant parameters impacting on the liquid transport are the cross-section A, the volume V respectively the change over time thereof, and the length L of the transport regions, and the viscosity ⁇ of the transported liquid.
- the macroscopic transport properties are mainly depending on the pore size distribution, the porosity, the tortuosity and the surface properties such as hydrophilicity.
- the permeability of the port regions should be high so as to allow large flux rates there through.
- typical permeability values for port regions or port region materials will range from about 6*10 "20 m 2 , to 7*10 "18 m 2 , or
- a further parameter relevant for port regions and respective materials is the bubble point pressure, which can be measured according to the method as described hereinafter.
- Suitable bubble point pressure values depend on the type of application in mind.
- the table below lists ranges of suitable port region bubble point pressure (bpp) for some applications, as determined for respective typical fluids: Application bpp (kPa) broad range typical range
- the port region of a liquid transport member is defined as the part of the wall having the highest permeability.
- the port region is also defined by having the lowest relative permeability when looking along a path from the bulk region to a point outside the transport member.
- the port region can be constructed by readily discernible materials, and then both thickness and size can be readily determined.
- the port region can, however, have a gradual transition of its properties either to other, impermeable regions of the wall region, or to the bulk region. Then the determination of the thickness and of the size can be made as described hereinafter.
- a segment of the wall region such as depicted in Figure 5A, this will have a surface, defined by the cornerpoints ABCD, which is oriented towards the inner or bulk region, and a surface EFGH oriented towards the outside of the member.
- the thickness dimension is oriented along the lines AE, BF, and so on, i.e. when using Cartesian co-ordinates, along the z-direction.
- the wall region will have the major extension along the two perpendicular directions, i.e. x-, and y- direction.
- the port region thickness can be determined as follows: a) In case of essentially homogeneous port region properties at least in the direction through the thickness of the region, it is the thickness of a material having such a homogeneous permeability (such as with a membrane film); b) It is the thickness of the membrane if this is combined with a carrier (be this carrier inside or outside of the membrane) - i.e. this refers to a non- continuous / step change function of the properties along this path.
- the "upper port region permeability" is determined as being 10 times the value of k min c3) As the curve has a minimum at k min there will be two corresponding r jnner ar
- Typical thickness values are in the range of less than 100 ⁇ m, often less than 50 ⁇ m, 10 ⁇ m, or even less than 5 ⁇ m.
- the x-y extension of the port region can be determined.
- which part of the wall region are port regions.
- the local permeability curves along the x- and y direction of the wall region can be determined, and plotted analogously to Figure 5B as shown in Figure 5C.
- the maximum permeability in the wall region defines the port regions, hence the maximum will be determined, and the region having permeabilities of not less than a tenth of the maximum permeability surrounding this maximum is defined as the port region.
- permeability to thickness ratio which in the context of the present invention is also referred to as "membrane conductivity”. This reflects the fact, that - for a given driving force - the amount of liquid penetrating through a material such as a membrane is on one side proportional to the permeability of the material, i.e. the higher the permeability, the more liquid will penetrate, and on the other side inversely proportional the thickness of the material.
- a material having a lower permeability compared to the same material having a decrease in thickness shows that thickness can compensate for this permeability deficiency (when regarding high rates a being desirable).
- this parameter can be very useful for designing the port region materials to be used.
- Suitable conductivity k/d depends on the type of application in mind. The table below lists ranges of typical k/d for some exemplary applications: Application k/d (10 "9 m) broad range typical range Diapers 10 "6 to 1000 150 to 300
- the port regions have to be wettable by the transport fluid, and the hydrophilicity or lipophilicity should be designed appropriately, such as by using hydrophilic membranes in case of transporting aqueous liquids, or hydrophobic membranes in case of lipophilic or oily liquids.
- the surface properties in the port region can be permanent, or they can change with time, or usage conditions. It is preferred, that the receding contact angle for the liquid to be transported is less than 70°, more preferably less than 50°, even more preferred less than 20° or even less than 10°. Further, often it is preferred, that the material has no negative impact on the surface tension of the transported liquid.
- a lipohilic membrane may be made from lipophilic polymers such as polyethylene or polypropylene and such membranes will remain liphophilic during use.
- hydrophilic material allowing aqueous liquids to be transported. If a polymer like polyethylene or polypropylene is to be used, this has to be hydrophilized, such as by surfactants added to the surface of the material or added to the bulk polymer, such as adding a hydrophilic polymer prior to forming the port material.
- the imparted hydrophilicity may be permanent or not, e.g. it could be washed away with the transport liquid passing therethrough.
- the lack of hydrophilizer will not be significant once the port regions are wetted.
- the port region may be sealed with soluble polymers, such as poly vinyl alcohol, or poly vinyl acetate, which are dissolved upon contact with liquids and which thereby activate the functionality of the transport member.
- soluble polymers such as poly vinyl alcohol, or poly vinyl acetate
- the port regions should satisfy certain mechanical requirements.
- the port regions should not have any negative effect on the intended use conditions. For example when such members are intended in hygienic absorbent articles, the comfort and safety must not be negatively impacted.
- the port regions are soft, and flexible, but this may not always be the case.
- the port region should be sufficiently strong to withstand practical use stress, such as tear stress or puncturing stress or the like.
- the port region materials it might be desirable for the port region materials to be extensible or collapsible, or bendable. Even a single hole in the membrane (e.g. caused by puncturing during use), a failure in membrane sealing (e.g. owing to production), or the membrane tearing (e.g. due to in-use pressure being exerted) can under various conditions lead to a failure of the liquid transport mechanism. Whilst this can be used as a destructive test method to determine if a materials or member functions according the present invention, and as described hereinafter, this is not desirable during its intended use. If air or another gas penetrates into the inner region, this may block the liquid flow path within the region, or it may also interrupt the liquid connection between the bulk and port regions.
- a possibility to make an individual member more robust is to provide in certain parts of the inner region remote from the main liquid flow path, a pocket where air that enters the system is allowed to accumulate without rendering the system non functional.
- a further way to address this issue is to have several liquid transport member in a (functionally or geometrically) parallel arrangement instead of a single liquid transport member. If one of the members fails, the others will maintain the functionality of the "liquid transport member battery".
- the above functional requirements of the port regions can be satisfied by a wide range of materials or structures described by the following structural properties or parameters.
- the pore structure of the region, respectively of the materials therein, is an important parameter impacting on properties like permeability and bubble point pressure.
- pore size Two key aspects of the pore structure are the pore size, and pore size distribution.
- a suitable method to characterize these parameters at least on the surface of the region is by optical analysis.
- Another suitable method for the characterization of these properties and parameters is the use of a Capillary Flow
- permeability is influenced by the pore size and the thickness of the regions, respectively the part of the thickness which is predominantly determining the permeability.
- the pores have preferably an average size of less than 100 ⁇ m, preferably less than 50 ⁇ m, more preferably less than 10 ⁇ m or even less than 5 ⁇ m. Typically, these pores are not smaller than 1 ⁇ m.
- bubble point pressure It is an important feature for example of the bubble point pressure, that this will depend on the largest pores in the region, which are in a connected arrangement therein. For example, having one larger pore embedded in small ones does not necessarily harm the performance, whilst a "cluster" of larger pores together might very well do so.
- pore walls such as pore wall thickness
- the pores should be well connected to each other along the flow direction, to allow liquid passing through readily.
- the preferred port region materials can be thin membrane materials, these in themselves may have relatively poor mechanical properties.
- such membranes can be combined with a support structure, such as a coarser mesh, threads or filaments, a non-woven, apertured films, or the like.
- Such a support structure could be combined with the membrane such that it is positioned towards the inner / bulk region or towards the outside of the member.
- the size of the port regions is essential for the overall performance of the transport member, and needs to be determined in combination with the "permeability to thickness" (k/d) rati0 of the port region.
- the size has to be adapted to the intended use, so as to satisfy the liquid handling requirements.
- the flux of the port regions will generally be lower than the flux through the inner region, it may be preferred to design the port regions larger in size (surface) than the cross-section of the inner region.
- the exact design and shape of the port regions can vary over a wide range.
- the port regions can be relatively small, such as about the size of the cross-section of the inner region, such that a substantially smaller transport member results.
- the member when liquids are to be quickly captured and transported, distributed or stored, the member can be shaped for example in the shape of a , dog bone with relatively large port regions at either end of the transport member or alternatively, the port regions can be spoon shaped so as to increase the receiving area.
- the port regions can be non-flat, such as for example corrugated, or folded, or having other forms so as to create relative large surface area to volume ratios, such as well known in the filter technology.
- the inlet port and the outlet port can be designed to satisfy the same basic requirements, and thus can be one and the same material, this does not need to be the case.
- the inlet and outlet port regions can be different with regard to one or more material or performance parameters.
- the different port regions can be readily discernible, such as by being represented by different materials and/or by being separated by other materials, or the port regions can differ by a property or parameter gradient, which can be continuous or stepwise.
- One essentially continuous material can have a gradient of properties along either the surface of the material, in the thickness dimension, or both, so as to be able to represent several parts of the wall or inlet or outlet port regions.
- the port region properties may be constant over time, or they may change with time, such as being different before and during use.
- the port regions can have properties unsuitable for functioning in members according to the present invention until the point of use.
- the port regions may be activated, for example by manual activation, intervention by the person using the member, or by an automatic activation means, such as by wetting of the transport member.
- Other alternative mechanisms for activation of the port regions can include temperature changes, for example to the body temperature of a wearer, or pH, for example of the transport liquid, or an electrical or mechanical stimulus.
- membranes useful for the present invention have no specific requirement of a certain salt impermeability.
- Suitable materials can be open celled foams, such as High Internal Phase
- Emulsion foams can be Cellulose Nitrate Membranes, Cellulose Acetate Membranes, Polyvinyldifluorid films, non-wovens, woven materials such as meshes made from metal, or polymers as Polyamide, or Polyester.
- Other suitable materials can be apertured Films, such as vacuum formed, hydroapertured, mechanically or Laser apertured, or films treated by electron, ion or heavy-ion beams.
- Specific materials are Cellulose acetate membranes, such as also disclosed in US 5,108,383 (White, Allied-Signal Inc.), Nitrocellulose membranes such as available from e.g. from Advanced Microdevices (PVT) LTD, Ambala Cantt.
- CNJ-10 Lit # F 030328
- CNJ-20 Lit # F 024248
- Cellulose acetat membranes Cellulose nitrate membranes
- PTFE membranes Polyamide membranes
- Polyester membranes as available e.g. from Sartorius in Gottingen, Germany and Millipore in Bedford USA, can be very suitable.
- microporous films such as PE/PP film filled with CaCO 3 particles, or filler containing PET films as disclosed in EP-A-0.451.797.
- port region materials can be ion beam apertured polymer films, such as made from PE such as described in "Ion Tracks and Microtechnology - Basic Principles and Applications” edited by R. Spohr and K.Bethge, published by Vieweg, Wiesbaden, Germany 1990.
- woven polymeric meshes such as polyamide or polyethylene meshes as available from Verseidag in Geldern-Waldbeck, Germany, or SEFAR in R ⁇ schlikon, Switzerland.
- Other materials which can be suitable for present applications are hydrophilized wovens, such as known under the designation DRYLOFT® from Goretex in Newark, DE 19711, USA.
- non-woven materials are suitable, such as available under the designation CoroGard ® from BBA Corovin, Peine, Germany, can be used, namely if such webs are specially designed towards a relatively narrow pore size distribution, such as by comprising suitable "melt-blown" webs.
- metal filter meshes of the appropriate pore size can be suitable, such as HIGHFLOW of Haver & Bocker, in Oelde, Germany. Additional Elements
- a support structure may be added to the outside of the wall or port region, which may be so open that it does not impact on the fluid handling properties, and as such would be considered functionally to belong to the outer region.
- an open support element extends from the wall region info the inner or bulk region, it will functionally belong to the bulk region. If there is a gradual transition between these materials and/or elements, the definitions made for the respective functional regions will enable a clear distinction of the region forming materials, and the additional elements.
- liquid transport member according to the present invention can optionally contain other elements, such as liquid impermeable walls or separations, in addition to the wall region with one or more port regions.
- elements outside of the wall regions such as materials to provide enhanced physical strength, or improved tactile feel or the like. Whilst such external elements might be arranged such that liquid flows there-through, they do not contribute to the essential functionality of the liquid transport member. Thus, such elements should not be a flow limiting factor, and may not function as a port region. Such elements can be integral with the wall region.
- both liquid transport members according to the present invention do not draw air into their respective structures, for conventional materials, fibrous materials or conventional foams, the liquid pulled into the structure displaces air within the structure.
- conventional porous materials such as fibrous structures, typically do draw air into themselves during desorption, air enters as liquid is drawn out of the structure.
- the liquid transport member according to the present invention does not draw air into the structure under normal usage conditions.
- the property that determines the point at which air will enter the system is referred to herein as bubble point pressure. Air will not enter the transport member until the bubble point pressure (bpp) is reached, due to the membrane functionality of the port region(s) material. Thus, once liquid has entered the member, it will not be replaced by air - up to the bpp of the member.
- a further property of the liquid transport member is the permeability k (liquid transport member) as the average permeability along the flow path of the transported liquid.
- the liquid transport member according to the present invention has a permeability which is higher than the permeability of a capillary system with equal liquid transport capability. This property is referred to as the a "critical permeability" k(crit).
- the critical permeability of the liquid transport member of the present invention is preferably at least twice as high as a capillary system with equal vertical liquid transport capability more preferably at least four times as high, and most preferably at least ten times greater than a capillary system with equal vertical liquid transport capability.
- bpp ⁇ liquid transport member ⁇ is the bubble point pressure of the liquid transport member, expressed in [kPa], as discussed in the above.
- the permeability of a material or transport member can be determined by various methods, such as by using the Liquid Transport test or the Permeability Test, both as described hereinafter, and then compared to the critical permeability as calculated from the above equations.
- suitable bpp for the member depends on the intended use, and suitable as well as typical values and ranges are essentially the same for the member as for the port region as described above.
- a liquid transport member according to the present invention can also be described by being substantially air impermeable up to a certain bpp, whereby the liquid transport member of the present invention has an overall permeability which is higher than the permeability for a given material having a homogeneous pore size distribution and an equivalent bpp.
- the liquid transport member according to the present invention should have a relatively high bpp ⁇ liquid transport member ⁇ and a high k ⁇ liquid transport member ⁇ at the same time.
- This can be graphically represented when plotting k ⁇ liquid transport member ⁇ over bbp in a double logarithmic diagram (as in Fig. 6 wherein the bbp is expressed in "cm height of water column", which then can be readily converted into a pressure).
- a top left to down right correlation can be observed.
- Members according to the present invention are have properties in the upper right region (I) above the separation line (L), whilst properties of conventional materials are much more in the left lower corner in the region (II), and have the limitations of the pure capillary transport mechanism, as schematically indicated by the straight line in the log-log diagram.
- the flow resistance is independent from the driving force as long as the pressure differential is less than the bpp of the transparent member.
- the flux is proportional to the driving pressure (up to the bpp).
- a liquid transport member according to the present invention can further be described by having high flux rates, as calculated on the cross-sectional area of the inner region.
- the member should have an average flux rate at 0.9kPa additional suction pressure differential to the height H 0 when tested in the Liquid Transport Test at a height H 0 , as described herein after, of at least 0.1 g/s/cm 2 , preferably of at least 1g/cm 2 /sec, more preferably at least 5 g/cm 2 /sec, even more preferably at least 10 g/cm 2 /sec, or even at least 20 g/cm 2 /sec, and most preferably at least 50 g/cm 2 /sec.
- the liquid transport member should have a certain mechanical resistance against external pressure or forces.
- the mechanical resistance to external pressures or forces can be relatively high to prevent squeezing liquid out of , the transport member, which for example, can be achieved by using stiff / non-deformable material in the inner region.
- this resistance can be in a medium range, thus allowing exploitation of external pressure or forces on the transport member for creating a "pumping effect".
- suitable structures for a liquid transport member the above mentioned simple example of a hollow tube having an inlet and outlet, said inlet and outlet being covered, i.e. closed, by membranes is considered.
- This type of structure can alternatively include a further support structure such as an open mesh attached to the port region membrane towards the inner region.
- the permeability requirement can be satisfied by the membrane itself, i.e. not considering the effect of the support structure, if the support structure is sufficiently open to have no negative impact on the overall permeability or on the liquid handling properties thereof.
- the thickness of the port region refers to the thickness of the membrane only - i.e. not including the thickness of the support structure. It will become apparent in the specific context, if for example such a support structure should be seen as an element of the port region having no significant impact on the port region properties, or - for example if the support structure has a significant thickness and thus impacts on the permeability for the liquid after the port region is penetrated - whether the support structure should be considered as a part of the inner region.
- the support structure becomes more extended in thickness, still remaining connected with the membrane, it yet can be considered as functionally belonging to the inner region, such as when the permeability of the composite "support - inner void" is significantly impacted by the permeability of the support structure.
- this principle should be considered for each of the respective aspects, such as when looking at the port region(s), the bulk regions or the complete transport member.
- the following describes how various elements can be combined to create structures suitable as a liquid transport member. It should be noted, that because of the multiple design options one or the other structure might not be discernible by all of the above described properties, but it will be readily apparent to the skilled person to design even further options following the general teachings in combination with the more specific embodiments.
- both the inner/bulk region and the port regions can be determined independently, it is preferred that one or both of the port regions have a lower liquid permeability than the inner region.
- a liquid transport member should have a ratio of the permeability of the bulk region to the port region of preferably at least 10:1, more preferably at least 100:1, even more preferably at least 1000:1 , even ratios of 100,000:1 are suitable.
- the inner/bulk region should comprise larger pores than the wall region.
- the pore size ratio of inner pores to port region pores are preferably at least 3:1 , more preferably at least 10:1 , even more preferably at least 100:1 and most preferable at least 350:1.
- the area of the port regions will typically be as large larger than the cross- section of the inner regions, thereby considering the respective regions together, namely - if present - the inlet regions or respectively the outlet regions. In most instance, the port regions will be twice as large as said inner region cross- section, often four times as large, or even 10 times as large.
- the various regions can have , similar structural properties or different, possibly complementing structural properties, such as strength, flexibility, and the like.
- all regions can comprise flexible material designed to cooperatively deform, whereby the inner region comprises a thin-until-wet material which expands upon contact with the transported liquid, the port region(s) comprise flexible membranes, and the walls can be made of liquid impermeable flexible film.
- the liquid transport member can be made of various materials, whereby each region may comprise one or more materials.
- the inner region may comprise porous materials
- the walls may comprise a film material
- the ports may comprise a membrane material.
- the transport member may consist essentially of one material with different properties in various regions, such as a foam with very large pores to provide the functionality of the inner region, and smaller pores surrounding these with membrane functionality as port materials.
- Such members can be considered to be a "Closed Distribution Member", as the inner region (703) is "enclosed” by the wall region (702) comprising port regions (706, 707). It is characteristic for such systems, that - once the transport member is activated, or equilibrated - a puncturing of the outer wall region can interrupt the transport mechanism. The transport mechanism can be maintained if only a small amount of air enters the system. This small quantity of air can be accumulated in an area of the inner region wherein it is not detrimental to the liquid transport mechanism.
- the liquid transport member may comprise several inlet and/or several outlet port regions, for example as can be achieved by connecting a number of tubes (802) together and closing several end openings with inlet ports 806 and an outlet port 807, thereby circumscribing the inner region 803, or a "split" system where fluid is transported simultaneously to more than one location (more than one exit port).
- the transport to different locations may be selective (e.g., the voids in a transport material on the route to one port may be filled with a water soluble material, and the voids in the transport material on the route to a second port may be filled with an oil soluble material.
- the transport medium may be hydro- and/or oleophilic to further enhance the selectivity.
- the inner region (903) can be segmented into more than one region, such as can be visualized by looking a bundle of parallel pipes, held in position by any suitable fixation means
- the outer wall region consists essentially of permeable port region (1006), i.e., the inner region (1003) is not circumscribed by any impermeable region at all.
- the port region may have the same permeability, or can have a different degree of permeability.
- the inner region may be wrapped by a membrane material.
- the port region and the inner region can be connected by a gradual transition region, such that the transport member appears to be a unitary material with varying properties.
- the liquid transport member can have one or more port regions (1 106), these being either inlet or outlet port regions, i.e., the member is designed to receive and/or release liquid.
- parts of the wall region (1 102) can be deformable, such that the total member can increase the volume of the inner region (1 103), so as to accommodate the additionally received volume of liquid, or so as to accommodate the initially contained liquid, which then can be released through the port region(s).
- a liquid sink or source can be integrally combined with the liquid transport member.
- the liquid transport member can have a liquid sink or source integrally incorporated therein, such as depicted by elements (1 1 1 1 ) in Fig. 1 1.
- (White) disclosure can be considered as a liquid transport member according to the present invention if - and only if - these are modified according to the requirements for the bulk region and port regions as defined herein above. Because of the specific functioning mechanism, these structures otherwise miss the broad applicability of the present invention, which is - due to the additional requirements for the inner and port regions - not restricted to osmotic driving forces (i.e. the presence of promoters), nor do the membranes of the present invention have to satisfy the salt rejection properties required by the MOP structures according to US-A-5.108.383.
- a further embodiment can comprise highly absorbent materials such as superabsorbent materials or other highly absorbent materials as described in more detail in U.S. Patent Application Serial No.
- a further embodiment of such an system with a liquid sink integral with the liquid transport member is a "Thin-until-wet" material in combination with a suitable membrane.
- Such materials are well known such as from US-A-5.108.383, which are open celled porous hydrophilic foam materials, such as produced by High Internal Phase Emulsion process.
- the pore size, polymer strength, Glass Transition Temperature T g ) and the hydrophilic properties are designed such that the pores collapse when they are dewatered and at least partially dried, and expand upon wetting.
- a specific embodiment is a foam layer, which can expand its caliper upon absorption of liquid, and (re-) collapse upon further removal of liquid.
- the inner region can be void of liquid at the beginning of the liquid transport process (i.e. contains a gas at a pressure less than the ambient pressure surrounding the liquid transport member).
- the liquid supplied by a liquid source can penetrate through the inlet port region(s) to first fill the voids of the membrane and then the inner region. The wetting then initiates the transport mechanisms according to the present invention thereby wetting, and penetrating the outlet port region.
- the inner regions may not be completely filled with the transport fluid, but a certain amount of residual gas or vapor may be retained.
- the gas or vapor is soluble in the transported liquid, it is possible that after some liquid passes through the member, that substantially all of the initially present gas or vapor is removed, and the inner regions become substantially free of voids. Of course, in cases with some residual gas or vapor being present in the inner region, this may reduce the effective available cross-section of the fluid member, unless specific measures are taken, such as indicated in Fig.12, with wall region (1202) comprising port regions (1206 and 1207) circumscribing the inner region (1203) and with region (1210) to allow gas to accumulate.
- the member can be filled with an aqueous based liquid, and the transport mechanism is such, that a non-aqueous, possibly immiscible liquid (like oil) enters the liquid transport member via the inlet port while the aqueous liquid leaves the member via the outlet port.
- a non-aqueous, possibly immiscible liquid like oil
- a Liquid Transport System within the scope of the present invention comprises the combination of at least one liquid transport member with at least one further liquid sink or source in liquid communication with the member.
- A. System can further comprise multiple sinks or sources, and also can comprise multiple liquid transport members, such as in a parallel arrangement. The latter can create a redundancy, so as to ensure functionality of the system even if a transport member fails.
- the source can be any form of free liquid or loosely bound liquid so as to be readily available to be received by the transport member.
- a pool of liquid or a freely flowing volume of liquid, or an open porous structure filled with liquid.
- the sink can be any form of a liquid receiving region. In certain embodiments, it is preferred to have the liquid more tightly bound than the liquid in the liquid source.
- the sink can also be an element or region containing free liquid, such that the liquid would be able to flow freely or gravity driven away from the member.
- the sink can contain absorbent, or superabsorbent material, absorbent foams, expandable foams, alternatively it can be made of a spring activated bellows system, or it can contain osmotically functioning material, or combinations thereof.
- Liquid communication in this context refers to the ability of liquids to transfer or to be transferred from the sink or source to the member, such as can be readily achieved by contacting the elements, or bringing the elements so closely together, that the liquid can bridge the remaining gap.
- Such a liquid transport system comprises a liquid transport member according to the above description plus at least one liquid sink or source.
- the liquid transport member can have liquid releasing or receiving properties in addition to a sink or source outside of the member.
- the port region(s) must be in liquid communication with the source liquid and where applicable the sink material.
- One approach is to have the port region material form the outer surface of the liquid transport member, in part or as the whole outer surface, so as to allow liquids such as liquids of the liquid source or sink to readily contact the port regions.
- the effective port region size can be determined by the size of the liquid communication with the sink or source respectively. For example, the total of the port regions can be in contact with the sink or source, or only a part thereof.
- this can be distinguished into separate effective inlet port regions and effective outlet port regions where the port region is in contact with the liquid source and/or sink, respectively.
- a liquid source for a liquid transport member can be a free flowing liquid, such as urine released by a wearer, or a open water reservoir.
- a liquid source region 1303 can also be an intermediate reservoir, such as a liquid acquisition member in absorbent articles.
- a liquid sink can be a free flow channel, or an expanding reservoir, e.g., a bellowed element combined with mechanical expansion or spacer means, such as springs.
- a liquid sink region can also be an ultimate liquid storage element of absorbent members, such as being useful in absorbent articles and the like.
- Two or more liquid transport systems according to the present invention can also be arranged in a "cascading design" (Fig. 13), with wall regions (1302), port regions (1306, 1307) and liquid sink materials (1311).
- Fig. 13 a "cascading design"
- the overall fluid flow path will go through one liquid transport system after the next.
- the inlet port region of a subsequent liquid transport system can take over the sink functionality of a previous system, such as when the inlet and outlet port regions are in fluid communication with each other.
- Such a fluid communication can be direct contact, or can be via an intermediate material.
- a specific embodiment of such a "cascade” can be seen in connecting two or more "membrane osmotic packets" comprising membranes of appropriate properties, whereby the osmotic suction power increases with subsequent packets.
- Each of the packets can then be considered a liquid transport member, and the connection between the packets will define the inlet and outlet port regions of each packet or member.
- the packets can be enclosed by one material (such as one type of flexible membrane), or even several packets can have a unitary membrane element.
- a liquid transport system has an absorption capacity of at least 5g/g, preferably at least 10 g/g, more preferably at least
- the liquid transport system contains a sink comprising an absorbent material having a capillary and/or osmotic absorption capacity of at least 10 g/g, preferably at least 20 g/g and more preferably at least 50 g/g, on the basis of the weight of the absorbent material, when measured in the Teabag Centrifuge Capacity Test, as described hereinafter.
- the liquid transport system comprises an absorbent material providing an absorbent capacity of at least 5 g/g, preferably at least 10 g/g, more preferably at least 50 g/g, or most preferably of at least 75 g/g up to a capillary suction corresponding to the bubble point pressure of the member, especially of at least 4 kPa, preferably at least 10 kPa, when submitted to the Capillary Sorption test, such as described in the test section of the copending PCT application US98/13497, filed June 29, 1998.
- Such materials further exhibit preferably a low absorbent capacity in the Capillary Sorption Test above the bubble point pressure, such as 4kPa or even 10 kPa, of less than 5 g/g, preferably less than 2 g/g, more preferably less than 1 g/g, and most preferably less than 0.2 g/g.
- the liquid transport member can contain superabsorbent materials or foam made according to the High Internal Phase Emulsion polymerization, such as described in PCT application US98/05044. Typically, the suction of the liquid sink material will not exceed the bubble point pressure of the port region.
- the article can be a water transport system or member, optionally combining transport functionality with filtration functionality, e.g. by purifying water which is transported.
- the member can be useful in cleaning operation, so as by removing liquids or as by releasing fluids in a controlled manner.
- a liquid transport member according to the present invention can also be a oil or grease absorber.
- One specific application can be seen in self-regulating irrigation systems for plants. Thereby, the inlet port can be immersed into a reservoir, and the transport member can be in the form of a long tube. In contrast to known irrigation systems
- the system according to the present invention will not loose its functionality upon drying of the reservoir, but remain functional until and after the reservoir is refilled.
- Yet a further application is the replacement of miniature pumps, such as can be envisaged in biological systems, or even in the medical field.
- An even further application can be seen in selective transport of liquids, such as when aiming at transporting oil away from an oil/water mixture.
- a liquid transport member can be used to transfer the oil into a further reservoir.
- oil can be transported into a liquid transport member comprising therein a sink functionality for oil.
- An even further application uses the liquid transport member according to the present invention as a transmitter for a signal. In such an application, the total amount of transported liquid does not need to be very large, but rather the transport times should be short.
- This liquid can then be used to stimulate further reaction, such as a signal or activated a response, e.g., dissolving a seal to release stored mechanical energy to create a three dimensional change in shape or structure.
- An absorbent article generally comprises:
- an absorbent core or core structure (which may comprise the improved fluid transport members according to the present invention, and which may consist of additional sub-structures); - a fluid pervious topsheet;
- Figure 14 is a plan view of an exemplary embodiment of an absorbent article of the invention which is a diaper.
- the diaper 1420 is shown in Figure 14 in its flat-out, uncontracted state (i.e. with elastic induced contraction pulled out except in the side panels wherein the elastic is left in its relaxed condition) with portions of the structure being cut-away to more clearly show the construction of the diaper 1420 and with the portion of the diaper 1420 which faces away from the wearer, the outer surface 1452, facing the viewer.
- the diaper 1420 comprises a containment assembly 1422 preferably comprising a liquid pervious topsheet 1424, a liquid impervious backsheet 1426 joined with the topsheet 1424, and an absorbent core 1428 positioned between the topsheet 1424 and the backsheet 1426; elasticized side panels 1430; elasticized leg cuffs 1432; an elastic waist feature 1434; and a closure system comprising a dual tension fastening system generally multiply designated as 1436.
- the dual tension fastening system 1436 preferably comprises a primary fastening system 1438 and a waist closure system 1440.
- the primary fastening system 1438 preferably comprises a pair of securement members 1442 and a landing member 1444.
- the waist closure system 1440 is shown in Figure 14 to preferably comprise a pair of first attachment components 1446 and a second attachment component 1448.
- the diaper 1420 also preferably comprises a positioning patch 1450 located subjacent each first attachment component 1446.
- the diaper 1420 is shown in Figure 14 to have an outer surface 1452
- the inner surface 1454 of the diaper 1420 comprises that portion of the diaper 1420 which is positioned adjacent to the wearer's body during use (i.e. the inner surface 1454 generally is formed by at least a portion of the topsheet 1424 and other components joined to the topsheet 1424).
- the outer surface 1452 comprises that portion of the diaper 1420 which is positioned away from the wearer's body (i.e.
- the outer surface 1452 generally is formed by at least a portion of the backsheet 1426 and other components joined to the backsheet 1426).
- the first waist region 1456 and the second waist region 1458 extend, respectively, from the end edges 1464 of the periphery 1460 to the lateral centerline 1466 of the diaper 1420.
- the waist regions each comprise a central region 1468 and a pair of side panels which typically comprise the outer lateral portions of the waist regions.
- the side panels positioned in the first waist region 1456 are designated 1470 while the side panels in the second waist region 1458 are designated 1472. While it is not necessary that the pairs of side panels or each side panel be identical, they are preferably mirror images one of the other.
- the side panels 1472 positioned in the second waist region 1458 can be elastically extensible in the lateral direction (i.e. elasticized side panels 1430).
- the lateral direction (x direction or width) is defined as the direction parallel to the lateral centreline 1466 of the diaper 1420; the longitudinal direction (y direction or length) being defined as the direction parallel to the longitudinal centreline 1467; and the axial direction (Z direction or thickness) being defined as the direction extending through the thickness of the diaper 1420).
- Figure 14 shows a specific of the diaper 1420 in which the topsheet 1424 and the backsheet 1426 have length and width dimensions generally larger than those of the absorbent core 1428.
- the topsheet 1424 and the backsheet 1426 extend beyond the edges of the absorbent core 1428 to thereby form the periphery 1460 of the diaper 1420.
- the periphery 1460 defines the outer perimeter or, in other words, the edges of the diaper 1420.
- the periphery 1460 comprises the longitudinal edges 1462 and the end edges 1464.
- each elasticized leg cuff 1432 may be configured so as to be similar to any of the leg bands, side flaps, barrier cuffs, or elastic cuffs described above, it is preferred that each elasticized leg cuff 1432 comprise at least an inner barrier cuff 1484 comprising a barrier flap 1485 and a spacing elastic member 1486 such as described in the above-referenced US Patent 4,909,803.
- the elasticized leg cuff 1432 additionally comprises an elastic gasketing cuff 14104 with one or more elastic strands 14105, positioned outboard of the barrier cuff 1484 such as described in the above-references US Patent 4,695,278.
- the diaper 1420 may further comprise an elastic waist feature 1434 that provides improved fit and containment.
- the elastic waist feature 1434 at least extends longitudinally outwardly from at least one of the waist edges 1483 of the absorbent core 1428 in at least the central region 1468 and generally forms at least a portion of the end edge 1464 of the diaper 1420.
- the elastic waist feature 1434 comprises that portion of the diaper at least extending from the waist edge 1483 of the absorbent core 1428 to the end edge 1464 of the diaper
- Disposable diapers are generally constructed so as to have two elastic waist features, one positioned in the first waist region and one positioned in the second waist region.
- the elasticized waist band 1435 of the elastic waist feature 1434 may comprise a portion of the topsheet 1424, a portion of the backsheet 1426 that has preferably been mechanically stretched and a bi-laminate material comprising an elastomeric member 1476 positioned between the topsheet 1424 and backsheet 1426 and resilient member 1477 positioned between backsheet 1426 and elastomeric member 1476.
- a bi-laminate material comprising an elastomeric member 1476 positioned between the topsheet 1424 and backsheet 1426 and resilient member 1477 positioned between backsheet 1426 and elastomeric member 1476.
- the absorbent core should be generally compressible, conformable, non- irritating to the wearer's skin, and capable of absorbing and retaining liquids such as urine and other certain body exudates.
- the absorbent core has a garment surface, a body surface, side edges, and waist edges.
- the absorbent core may - in addition to the liquid transport member according to the present invention - comprise a wide variety of liquid-absorbent or liquid handling materials commonly used in disposable diapers and other absorbent articles such as - but not limited to - comminuted wood pulp which is generally referred to as airfelt; meltblown polymers including co-form; chemically stiffened, modified or cross-linked cellulosic fibers; tissue including tissue wraps and tissue laminates.
- the absorbent core can be a unitary core structure, or it can be a combination of several absorbent structures, which in turn can consist of one or more sub-structures.
- Each of the structures or sub-structures can have an essentially two-dimensional extension (i.e. be a layer) or a three-dimensional shape.
- the liquid transport member according to the present invention can comprise at least one inlet port region, which should be located in the loading zone of the article.
- This port region can be made from flexible membrane material satisfying the requirements as described herein, which can be connected to a high resiliency, open fibrous structure forming the inner region, which can be wrapped in flexible impermeable films to form the wall regions which can be adhesively closed at all edges except for the port region.
- the impermeable film can overlap the port region somewhat so as to allow also adhesive bonding there between.
- Figure 15 shows a specific embodiment of an article as shown in Figure 14, - with analogous numerals - and Figure 16A shows a partly exploded simplified cross-sectional view along A - A of Figure 15, again with analogous numbering.
- an absorbent core (1528/1628) is made of suitable liquid handling member which is constructed from a wall region (1502,1602), port regions (1506, 1507, 1606), and inner region (1503, 1603).
- the member may be connected to a liquid sink (1511, 1611), and optionally a topsheet (1524, 1624) is attached.
- the sink (1511 , 1611) can comprise ultimate storage material, such as superabsorbent material, or highly absorbing porous material.
- the inner regions can be filled with liquid, such as water, so as to be ready for liquid transport there through immediately after receipt of the liquid at the inlet port.
- the inner region can be under a vacuum, which can suck in liquid through the inlet port such as upon activation of a barrier film like a polyvinyl alcohol film which can dissolve upon wetting.
- the embodiment as shown in Figure 16B differs from the one of Figure 16A in that the inner regions comprise ultimate liquid storage material, such as superabsorbent material, or highly absorbing porous material therein.
- ultimate liquid storage material such as superabsorbent material, or highly absorbing porous material therein.
- promotor materials for enhancing osmotic liquid storage mechanisms - such as disclosed in the hereinbefore mentioned US-publication US-A-5.108.383 (White, Allied Signal) - can be within the inner region.
- the absorbent core can be designed so as to not require any further fluid handling element.
- the area of the inlet port region can be adjusted to its permeability and caliper so as to enable the port region to immediately acquire the liquid at the gush rate, and the inner region can be adjusted by its permeability and cross-sectional area so as to immediately transmit the liquid to the ultimate storage region .
- the absorbent core may comprise other fluid handling elements, such as acquisition regions, or interim storage regions, or the like.
- the "cascading liquid transport member" or “MOP” can be suitable elements within the core construction.
- the liquid transport members according to the present invention can be produced by various methods, which have to have in common the essential steps of combining a bulk or inner region with a wall region comprising port regions with appropriate selection of the respective properties as described in the above. This can be achieved by starting from a homogeneous material, and imparting therein different properties. For example, if a member is a polymeric foam material, this can be produced form one monomer with varying pore sizes, which will then be polymerized to form a suitable member.
- a wall material can be provided, which may have homogeneous or varying properties
- a bulk material can be provided, which can be open porous material, or a void space can be defined to represent the bulk region.
- the two materials can the be combined by suitable techniques, such as by wrapping or enveloping as well known in the art, such that the wall material completely circumscribes the bulk region or bulk region material.
- the bulk region can be filled with liquid, or can be subjected to vacuum, or can be equipped with other aids so as to created vacuum, or liquid filling.
- the method of forming a member according to the present invention can comprise the step of applying activation means, which can be of the mechanical type such as by providing a removable release element, such as being well known for example as a release paper for covering adhesives, or by providing a packaging design, which allows the sealing of the member until use, whereby at the time of use such a packaging sealing is opened or removed.
- activation means can also comprise materials which react upon the transport liquid, such as dissolve. Such materials may be applied in the port regions, e.g. to open the port regions upon use, or such materials may be applied to the bulk regions, such as to allow expansion of these regions upon wetting.
- the making of members according to the present invention can be done in an essentially continuous way, such as by having various materials provided in roll form, which are then unwound and processed, or any of the materials can be provided in discrete form, such as foam pieces, or particulates.
- S-1.1 - Woven filter mesh HIFLO ®, type 20 such as available from Haver & Boecker, Oelde, Germany, made from stainless steel, having, designed for filtering down to 19 ⁇ m to 20 ⁇ m, at a porosity of 61%, and a caliper of 0.09 mm.
- S-1.2a - Polyamide mesh Monodur Type MON PA 20 N such as available from Verseidag in Geldern-Waldbeck, Germany.
- S-1.2b Polyamide mesh Monodur Type MON PA 42.5 N such as available from Verseidag in Geldern-Waldbeck, Germany.
- S-1.3a Polyester mesh such as 07-20/13 of SEFAR in R ⁇ schlikon, Switzerland.
- S-1.3b Polyamide mesh 03-15/10 of SEFAR in R ⁇ schlikon, Switzerland.
- S-1.3c Polyamide mesh 03-20/14 of SEFAR in R ⁇ schlikon, Switzerland.
- S-1.3e Polyamide mesh 03-5/1 of SEFAR in R ⁇ schlikon, Switzerland.
- S-1.3f Polyamide mesh 03-10/2 of SEFAR in R ⁇ schlikon, Switzerland.
- S-2.5 Conventional polyethylene film such as used as backsheet material in disposable diapers, such as available from Nuova Pansac SpA in Milano, Italy under the code BS code 441118.
- S-2.6 Flexible PVC tube e.g. Catalog # 620 853 84 from Fisher Scientific in
- S-3.2 Metallic springs having a outer diameter of 4 mm and a length of about 6 cm with any applied force, as available from Fedemfabrik Dietz in Neustadt, Germany under the designation "federn" article # DD/100.
- S-3.3 Open cell foams from Recticel in Brussels, Belgium such as Filtren
- S-3.5 Particulate pieces of S-3.4 or S-3.3.
- S-4.2 Height difference between inlet and outlet generating a hydrostatic height generated pressure difference.
- S-4.3 Various partially saturated porous materials (Absorbent foams, superabsorbent materials, particles, sand, soils) generating a capillary pressure difference.
- A-1 A ca 20 cm long tube (S-2.6) is connected in an air tight way with a plastic funnel (S-2.2). Sealing can be made with Parafilm M (available from Fischer Scientific in Nidderau, Germany catalog number 617 800 02). A circular piece of port material (S-1.1), slightly larger than the open area of the funnel is sealed in an air tight way with the funnel. Sealing is made with suitable adhesive, e.g., Pattex TM of Henkel KGA, Germany.
- suitable adhesive e.g., Pattex TM of Henkel KGA, Germany.
- a port region material may be connected to the lower end of the tube and be sealed in a air tight way.
- the device is filled with a liquid such as water by putting it under the liquid and removing the air inside the device with a vacuum pump tightly connected to the port region.
- the lower end does not need to be sealed with a port region, but then the lower end needs to be in contact with the liquid or needs to be the lowest part of the device in order to not allow air to enter the system.
- a ca 10 cm X 10 cm rectangular sheet of foam material (S-3.3, Filtren TM 10 blue) "sandwiched" on one side by a wall material as S-2.5 of dimensions ca 12 cm X 12 cm, on the other side by a port region material of dimensions ca 12 cm X 12 cm as S-1.3a.
- the wall material S-2.5 and the port region material S- 1.3a are sealed together in the overlap region in a convenient air tight way, e.g., by gluing with the above mentioned commercially available Pattex TM adhesive of Henkel KGA, Germany.
- the device is immersed under a liquid such as water, and by squeezing the device, air is forced out. Releasing squeezing pressure from the device whilst keeping it under liquid, the Inner region is filled with liquid.
- a vacuum pump can suck the remaining air inside the device through the port region while the device is under the liquid.
- Figures 17, 17A schematically show a distribution member, suitable for example for absorbent articles, such as a disposable diapers.
- the inlet port region (1706) is made of port region material such as S-1.3b
- the outlet port region (1705) is made of port region material such as S-1.3c.
- each of the port regions forms a pouch, which can have dimensions of about 10cm by 15 cm for the inlet port region respectively 20 cm by 15 cm for the outlet port region.
- the port materials of the pouches overlap in the crotch region (1790) of the article, and a tube (1760) is positioned therein.
- the inner regions within the pouches (1740, 1750) can be S-3.3 (Filtren TM10 blue), and the inlet and outlet regions respectively inner regions enclosed by them, can be connected by tubes (1760) such as S-2.6 of an inner diameter of about 8 mm.
- Wall and port material (1702, 1707, 1706) must be sufficiently larger than the inner material to allow airtight sealing of wall material to port material. Sealing is done by overlapping of a ca 1.5 cm wide stripe of wall and port material and can be done in any convenient air tight way e.g. by using the above mentioned Pattex TM adhesive.
- inlet (1806) and outlet port (1807) regions having a dimension of about 8 cm by 12 cm are made from sheets of port material S-1.2a , the other wall regions (1802) are made of wall material S-2.1.
- Inner material (1840) are stripes of material S-3.3 (Bulpren S10 black) having dimension of about 0.5 cm by 0.5 cm by 10 cm, placed at a distance of about 1 cm to each other, under the inlet and outlet regions (1806, 1807 respectively) and spacer springs S-3.2 (1812) in the remaining areas.
- Individual layers (wall and port material) are sealed and further filled with a liquid such as water as described in A-3.
- the device can be filled with other liquids in a similar fashion.
- Spacer materials such as springs according to S-3.2 are positioned between an upper and a lower sheet of port material S-1.2ba, having a dimension of 10 cm by 50 cm, such that the springs are equally distributed over the area in a region of about 7 cm times 47 cm leaving the outer rim (1813) of about 1.5 cm free of springs, with a distance of about 2 mm between the individual springs.
- Upper and lower port material are sealed in an air tight way by overlapping ca 1.5 cm and sealing in a convenient air tight way such as by gluing with the above mentioned Pattex TM adhesive.
- the device is immersed under the testing liquid, by squeezing the device air is forced to leave the interior of the device. Releasing the squeezing pressure while being immersed, the member will be filled with liquid.
- a vacuum pump can suck the remaining air from inside the member through the port region while the device is under the liquid.
- Example B for Transport system i.e. member and (source and/or sink)
- a liquid transport member according to A-1) is combined with particulate superabsorbent material, such a available under the designation W80232 from HULS-Stockhausen GmbH, Marl, Germany, with coarse particles being removed by sieving through a 300 ⁇ m metal sieve. 7.5 g of this material have been evenly sprinkled over the outlet port region of A-1 , thereby creating a liquid sink.
- particulate superabsorbent material such as available under the designation W80232 from HULS-Stockhausen GmbH, Marl, Germany
- a sheet of three layers of HIPE foam produced as for S-1.54 each having a thickness of about 2 mm, and a corresponding basis weight of about 120 g/m 2 are positioned on the outlet port of a liquid transport member according to A-1.
- the sheets were cut circular with a diameter of about 6 cm, and a segment of about 10° was cut out to provide better conformity to the port region surface.
- a weight corresponding to a pressure of about 0.2 psi can be applied to enhance liquid contact between outlet and sink material.
- the liquid transport member according to A-1 has been combined with a circular cut out section of ca 6 cm diameter taken from a commercially available diaper core, consisting of a essentially homogeneous blend of superabsorbent material such as ASAP2300 commercially available from CHEMDAL Corp. UK, and conventional airfelt at a 60 % by weight superabsorber concentration and a basis weight of the superabsorbent of about 400 g/m 2 ).
- This cut out is placed in liquid communication with the outlet port region of A-1 to create a liquid transport system.
- the liquid transport member of A-2 has been positioned between a liquid source reservoir and a flower pot, such that a portion of the inlet port region is immersed in the liquid reservoir, and the outlet port being put into the soil of the flower pot.
- the relative height of the reservoir and the flower pot is of no relevance for this length of the member, and would not be up to a length of the member of about
- a further application of a liquid transport system with an integral liquid sink which can be constructed by creating a liquid transport member as in A-3, but filling it with oil (instead of water).
- oil instead of water.
- the system will rapidly absorb the oil in the pan.
- the structure can function as a absorbent pad, whereby the urine as released by the wearer can be seen to provide the liquid source.
- activation means, that the member is put into the in use condition, such as by establishing a liquid communication along a flow path, or such as by initiating a driving pressure differential, and this can be achieved by mechanical activation simulating the pre-use activation of a user (such as the removal of a constraining means such as a clamp, or a strip of a release paper such as with an adhesive, or removal of a package seal, thereby allowing mechanical expansion optionally with creation of a vacuum within the member).
- Activation can further be achieved by another stimulus transmitted to the member, such as pH or temperature change, by radiation or the like.
- Activation can also be achieved by interaction with liquids, such as having certain solubility properties, or changing concentrations, or are carrying activation ingredients like enzymes.
- the member should be immersed in testing liquid which should be representative for the transport liquid, optionally removing the air by means of a vacuum pump, and allowing equilibration for 30 minutes. Then, the member is removed from the liquid, a put on a coarse mesh (such as a 14 mesh sieve) to allow dripping off of excess liquid.
- testing liquid which should be representative for the transport liquid
- the test provides a simple to execute tool to assess if a transport material or member satisfies the principles of the present invention. It should be noted, that this test is not useful to exclude materials or members, i.e. if a material or members does not pass the Closed System Test, it may or may not be a liquid transport member according to the present invention.
- the test specimen is activated as described herein above, and the weight is monitored. Then, the test specimen is suspended or supported in a position such that the longest extension of the sample is essentially aligned with the gravity vector.
- the sample can be supported by a support board or mesh arranged at an angle of close to 90° to the horizontal, or the sample can be suspended by straps or bands in a vertical position.
- the wall region is opened in the uppermost and in the lowermost parts of the sample, i.e., if the sample has opposite corners, then at these corners, if the sample has a curved or rounded periphery, then at the top and bottom of the sample.
- the size of the opening has to be such as to allow liquid passing through the lower opening and air passing through the upper opening which is sufficient to allow liquid flowing out without adding pressure or squeezing.
- an opening having an inscribed circular diameter of at least 2 mm is adequate.
- the opening should be done at a location of the material or member which is not positioned at the upper end of the member, as then no liquid could leave the member or material in analogy to a glass or cup which is open.
- the opening can be done by any suitable means, such as by using a pair of scissors, a clipping tongue, needle, a sharp knife or a scalpel and the like. If a slit is applied to the sample, it should be done such that the flankes of the slit can move away from each other, so as to create a two-dimensional opening. Alternatively, a cut can remove a part of the wall material thus creating an opening.
- the weight thereof is being monitored (such as by catching the liquid in a Petri dish, which is put on a scale.
- the weight of the material or member can be determined after 10 minutes and compared to the initial weight. Care should be taken, that no excessive evaporation takes place, if this would be the case, this can be determined by monitoring the weight loss of a sample without having it opened over the test time, and by then correcting the results accordingly.
- the tested material or member has passed this test, and is a liquid transport member according to the present invention.
- the port region respectively the port region material is connected with a funnel and a tube as described in example A-1. Thereby, the lower end of the tube is left open i.e. not covered by a port region material.
- the tube should be of sufficient length, i.e. up to 10m length may be required.
- test material is very thin, or fragile, it can be appropriate to support it by a very open support structure (as e.g. a layer of open pore non- woven material) before connecting it with the funnel and the tube.
- a very open support structure as e.g. a layer of open pore non- woven material
- the funnel may be replaced by a smaller one (e.g. Catalog # 625 616 02 from Fisher Scientific in Nidderau, Germany).
- testing liquid can be the transported Iquid, but for ease of comparison, the testing liquid should be a solution of 0.03% TRITON X 100, such as available from MERCK KGaA, Darmstadt, Germany, under the catalog number 1.08603, in destilled or deionized water, thus resulting in a surface tension of 33 mN/m, when measured according to the surface tension method as described further.
- the device is filled with testing liquid (e.g. distilled water, or oil depending on the intended use) by immersing it in a reservoir of sufficient size filled with the testing fluid and by removing the remaining air with a vacuum pump.
- the part of the funnel with the port region is taken out of the liquid. If appropriate - but not necessarily - the funnel with the port region material should remain horizontally aligned.
- the height Whilst slowly continuing to raise the port material above the reservoir, the height is monitored, and it is carefully observed through the funnel or through the port material itself (optionally aided by appropriate lighting) if air bubbles start to enter through the material into the inner of the funnel. At this point, the height above the reservoir is registered to be the bubble point height.
- BPP ⁇ g - H with the liquid density p, gravity constant g ( g « 9.81 m/s 2 ).
- an alternative determination can be used, such as commonly used for assessing bubble point pressures for membranes used in filtration systems.
- the wetted membrane is separating two gas filled chambers, when one is set under an increased gas pressure (such as an air pressure), and the point is registered when the first air bubbles "break through".
- an increased gas pressure such as an air pressure
- PMI permeameter or porosity meter as described in the test method section hereinafter, can be used for the bpp determination.
- Bubble point pressure (liquid transport member) For measuring the bubble point pressure of a liquid transport member
- the testing liquid can be the transported liquid, but for ease of comparison, the testing liquid should be a solution of 0.03 % TRITON X-100, such as available from MERCK KGaA, Darmstadt, Germany, in destilled or deionized water, resulting in a surface tension of 33 mN/m, when measured according to the surface tension method as desribed further.
- a part of a port region under evaluation is connected to a vacuum pump connected by a tightly sealed tube/pipe (such as with Pattex TM adhesive as described above).
- the vacuum pump should allow to set various pressures p vac , increasing from atmospheric pressure P atm to about 100 kPa .
- the pump is started to create a light vacuum, which is increased during the test in a stepwise operation.
- the amount of pressure increase will depend on the desired accuracy, with typical values of 0.1 kPa providing acceptable results.
- the flow will be monitored over time, and directly after the increase of ⁇ p, the flow will increase primarily because of removing gas from the tubing between the pump and the membrane. This flow will however, rather quickly level off, and upon establishing an equilibrium ⁇ p, the flow will essentially stop. This is typically reached after about 3 minutes.
- This step change increase is continued up to the break through point, which can be observed by the gas flow not decreasing after the step change of the pressure, but remaining after reaching an equilibrium level essentially constant over time.
- the pressure ⁇ p one step prior to this situation is the bpp of the liquid transport member.
- the surface tension measurement is well known to the man skilled in the art, such as with a Tensiometer K10T from Kr ⁇ ss GmbH, Hamburg, Germany using the DuNouy ring method as described in the equipment instructions. After cleaning the glassware with iso-propanol and de-ionized water, it is dried at 105°C. The Platinum ring is heated over a Bunsen-bumer until red heat. A first reference measurement is taken to check the accuracy of the tensiometer. A suitable number of test replicates is taken to ensure consistency of the data. The resulting surface tension of thet liquid as expressed in units of mN/m can be used to determine the adhesion tension values and surface energy parameter of the respective liquid/solid/gas systems. Destilled water will generally exhibit a surface tension value of 72mN/m, a 0.03% X-100 solution in water of 33 mN/m.
- the liquid transport member Before executing the test, the liquid transport member should be activated if necessary, as described in the above.
- the test specimen is placed in a vertical position over a liquid reservoir, such as by being suspended from a holder, such whereby the inlet port remains completely immersed in liquid in the reservoir
- the outlet port is connected such as via a flexible tubing of 6 mm outer diameter to a vacuum pump - optionally with a separator flask connected between the sample and the pump - and sealed in an air tight way as described in the above bubble point pressure method for a liquid transport member.
- the vacuum suction pressure differential can be monitored and adjusted.
- the lowermost point of the outlet port is adjusted to be at a height H 0 above the liquid level in the reservoir.
- the decrease of the weight of the liquid in the reservoir is monitored, preferably by positioning the reservoir on a scale measuring the weight of the reservoir, and connecting the scale to a computing equipment. After an initial unsteady decrease (typically taking not more than about one minute), the weight decrease in the reservoir will become constant (i.e. showing a straight line in a graphical data presentation). This constant weight decrease over time is the flow rate (in g/s) of the liquid transport member at suction of 0.9kPa and a height H 0 .
- the corresponding flux rate of the liquid transport member at 0.9kPa suction and a height H 0 is calculated from the flow rate by dividing the flow rate with the average cross section of the liquid transport member along a flow path, expressed in g/s/cm 2 . Care should be take, that the reservoir is large enough so that the fluid level in the reservoir does not change by more than 1 mm.
- the effective permeability of the liquid transport member can be calculated by dividing the flux rate by the average length along a flow path and the driving pressure difference (0.9kPa).
- test should be carried out with a suitable test fluid representing the transport fluid.
- a suitable test fluid representing the transport fluid.
- the formula for the synthetic urine is: 2.0 g/: of KCI; 2.0 g/l of Na2SO4; 0.85 g/l of (NH4)O4; 0.15 g/l (NH4)O4; 0.19 g/l of CaCI2; ad 0.23 g/l of MgCI2. All of the chemicals are of reagent grade.
- the pH of the synthetic Urine is in the range of 6.0 to 6.4.
- Test specimen are stored under these conditions for at least 24 hours before testing, and - if applicable - activated as described in the above.
- the present Permeability Test provides a measure for permeability for two special conditions: Either the permeability can be measured for a wide range of porous materials (such as non-wovens made of synthetic fibres, or cellulosic structures) at 100% saturation, or for materials, which reach different degrees of saturation with a proportional change in caliper without being filled with air (respectively the outside vapour phase), such as the collapsible polymeric foams, for which the permeability at varying degrees of saturation can readily be measured at various thicknesses.
- porous materials such as non-wovens made of synthetic fibres, or cellulosic structures
- permeability can be calculated - for a fixed or given sample cross- sectional area and test liquid viscosity - by measurement of pressure drop and the volumetric flow rate through the sample:
- the test can be executed in two modifications, the first referring to the transplanar permeability (i.e. the direction of flow is essentially along the thickness dimension of the material), the second being the in-plane permeability (i.e. the direction of flow being in the x-y-direction of the material).
- Figure 19 is a schematic diagram of the overall equipment and - as an insert diagram - a partly exploded cross-sectional, not to scale view of the sample cell.
- the test set-up comprises a generally circular or cylindrical sample cell (19120), having an upper (19121) and lower (19122) part. The distance of these parts can be measured and hence adjusted by means of each three circumferentially arranged caliper gauges (19145) and adjustment screws (19140). Further, the equipment comprises several fluid reservoirs (19150, 19154, 19156) including a height adjustment (19170) for the inlet reservoir (19150) as well as tubings (19180), quick release fittings (19189) for connecting the sample cell with the rest of the equipment, further valves (19182, 19184, 19186, 19188).
- the differential pressure transducer (19197) is connected via tubing (19180) to the upper pressure detection point (19194) and to the lower pressure detection point (19196).
- a Computer device (19190) for control of valves is further connected via connections (19199) to differential pressure transducer (19197), temperature probe (19192), and weight scale load cell (19198).
- the circular sample (191 10) having a diameter of 1 in (about 2.54 cm) is placed in between two porous screens (19135) inside the sample cell (19120), which is made of two 1 in (2.54 cm) inner diameter cylindrical pieces (19121 ,
- test sample (191 10) is compressed to the caliper corresponding to the desired wet compression, which is set to 0.2 psi (about 1.4 kPa) unless otherwise mentioned. Liquid is allowed to flow through the sample (191 10) to achieve steady state flow. Once steady state flow through the sample (19110) has been established, volumetric flow rate and pressure drop are recorded as a function of time using a load cell (19198) and the differential pressure transducer (19197). The experiment can be performed at any pressure head up to 80 cm water (about 7.8 kPa), which can be adjusted by the height adjusting device (19170). From these measurements, the flow rate at different pressures for the sample can be determined.
- the equipment is commercially available as a Permeameter such as supplied by Porous Materials, Inc, Ithaca, New York, US under the designation PMI Liquid Permeameter, such as further described in respective user manual of 2/97.
- This equipment includes two Stainless Steel Frits as porous screens (19135), also specified in said brochure.
- the equipment consists of the sample cell (19120), inlet reservoir (19150), outlet reservoir (19154), and waste reservoir (19156) and respective filling and emptying valves and connections, an electronic scale, and a computerized monitoring and valve control unit (19190).
- the gasket material (19115) is a Closed Cell Neoprene Sponge SNC-1
- Test fluid is deionized water. The test is then executed by the following steps:
- test it is determined, if one or more layers of the test sample are required, wherein the test as outlined below is run at the lowest and highest pressure. The number of layers is then adjusted so as to maintain the flow rate during the test between 0.5 cm 3 /seconds at the lowest pressure drop and 15 cm 3 /second at the highest pressure drop. The flow rate for the sample should be less than the flow rate for the blank at the same pressure drop. If the sample flow rate exceeds that of the blank for a given pressure drop, more layers should be added to decrease the flow rate. Sample size: Samples are cut to 1" (about 2.54 cm) diameter, by using an arch punch, such as supplied by McMaster-Carr Supply Company, Cleveland, OH, US.
- a conventional low basis weight support means can be added, such as a PET scrim or net.
- a PET scrim or net At least two samples (made of the required number of layers each, if necessary) are precut. Then, one of these is saturated in deionized water at the temperature the experiment is to be performed (70 ° F, (31 ° C) unless otherwise noted).
- the caliper of the wet sample is measured (if necessary after a stabilization time of 30 seconds) under the desired compression pressure for which the experiment will be run by using a conventional caliper gauge (such as supplied by AMES, Waltham, MASS, US) having a pressure foot diameter of 1 1/8 " (about 2.86 cm), exerting a pressure of 0.2 psi (about 1.4 kPa) on the sample (19110), unless otherwise desired.
- a conventional caliper gauge such as supplied by AMES, Waltham, MASS, US
- An appropriate combination of gasket materials is chosen, such that the total thickness of the gasketing foam (191 15) is between 150 and 200% of the thickness of the wet sample (note that a combination of varying thicknesses of gasket material may be needed to achieve the overall desired thickness).
- the gasket material (191 15) is cut to a circular size of 3" in diameter, and a 1 inch (2.54 cm) hole is cut into the center by using the arch punch.
- the sample should be cut such that the required diameter is taken in the wet stage. This can also be assessed in this preparatory test, with monitoring of the respective dimensions. If these change such that either a gap is formed, or the sample forms wrinkles which would prevent it from smoothly contacting the porous screens or frits, the cut diameter should be adjusted accordingly.
- test sample (191 10) is placed inside the hole in the gasket foam (191 15), and the composite is placed on top of the bottom half of the sample cell, ensuring that the sample is in flat, smooth contact with the screen (19135), and no gaps are formed at the sides.
- the top of the test cell (19121) is laid flat on the lab bench (or another horizontal plane) and all three caliper gauges (19145) mounted thereon are zeroed.
- the top of the test cell (19121) is then placed onto the bottom part (19122) such that the gasket material(19115) with the test sample (19110) lays in between the two parts.
- the top and bottom part are then tightened by the fixation screws (19140), such that the three caliper gauges are adjusted to the same value as measured for the wet sample under the respective pressure in the above.
- the inlet liquid reservoir (19150) is set to the required height and the test is started on the computerized unit (19190). 5) Then, the sample cell (19120) is positioned into the permeameter unit with Quick Disconnect fittings (19189).
- the sample cell (19120) is filled by opening the vent valve (19188) and the bottom fill valves (19184, 19186). During this step, care must be taken to remove air bubbles from the system, which can be achieved by turning the sample cell vertically, forcing air bubbles - if present - to exit the permeameter through the drain.
- the liquid outlet flow is automatically diverted from the waste reservoir (19156) to the outlet reservoir (19154), and pressure drop, and temperature are monitored as a function of time for several minutes.
- the computerized unit provides the recorded data (in numeric and/or graphical form).
- the same test sample can be used to measure the permeability at varying pressure heads, with thereby increasing the pressure from run to run.
- the equipment should be cleaned every two weeks, and calibrated at least once per week, especially the frits, the load cell, the thermocouple and the pressure transducer, thereby following the instructions of the equipment supplier.
- the differential pressure is recorded via the differential pressure transducer connected to the pressure probes measurement points (19194, 19196) in the top and bottom part of the sample cell. Since there may be other flow resistances within the chamber adding to the pressure that is recorded, each experiment must be corrected by a blank run. A blank run should be done at 10, 20, 30, 40, 50, 60, 70, 80 cm requested pressure, each day.
- the permeameter will output a Mean Test Pressure for each experiment and also an average flow rate.
- the flow rate is recorded as Blank Corrected Pressure by the computerized unit (19190), which is further correcting the Mean Test Pressure (Actual Pressure) at each height recorded pressure differentials to result in the Corrected Pressure.
- This Corrected Pressure is the DP that should be used in the permeability equation below.
- Permeability can then be calculated at each requested pressure and all permeabilities should be averaged to determine the k for the material being tested. Three measurements should be taken for each sample at each head and the results averaged and the standard deviation calculated. However, the same sample should be used, permeability measured at each head, and then a new sample should be used to do the second and third replicates.
- the measuring of the in-plane permeability under the same conditions as the above described transplanar permeability can be achieved by modifying the above equipment such as schematically depicted in Figures 20A and 20B showing the partly exploded, not to scale view of the sample cell only.
- Equivalent elements are denoted equivalently, such that the sample cell of Figure 20 is denoted (20210), correlating to the numeral (191 10) of figure 19, and so on.
- the transplanar sample cell (19120) of figure 19 is replaced by the in-plane simplified cell (20220), which is designed so that liquid can flow only in one direction (either machine direction or cross direction depending on how the sample is placed in the cell). Care should be taken to minimize channeling of liquid along the walls (wall effects), since this can erroneously give high permeability reading.
- the test procedure is then executed quite analogous to the transplanar test.
- the sample cell (20220) is designed to be positioned into the equipment essentially as described for the sample cell (19120) in the above transplanar test, except that the filling tube is directed to the inlet connection (20232) the bottom of the cell (20220).
- Figure 20A shows a partly exploded view of the sample cell, and Figure 20B a cross-sectional view through the sample level.
- the test cell (20220) is made up of two pieces: a bottom piece (20225) which is like a rectangular box with flanges, and a top piece (20223) that fits inside the bottom piece (20225) and has flanges as well.
- the test sample is cut to the size of 2" in x 2"in (about 5.1 cm by 5.1 cm) and is placed into the bottom piece.
- the top piece (20223) of the sample chamber is then placed into the bottom piece (20225) and sits on the test sample (20210).
- An incompressible neoprene rubber seal (20224) is attached to the upper piece (20223) to provide tight sealing.
- the test liquid flows from the inlet reservoir to the sample space via Tygon tubing and the inlet connection (20232) further through the outlet connection (20233) to the outlet reservoir.
- the sample is kept at the desired test temperature by the heating device (20226), whereby thermostated water is pumped through the heating chamber (20227).
- the gap in the test cell is set at the caliper corresponding to the desired wet compression, normally 0.2 psi ( about 1.4 kPa).
- Shims (20216) ranging in size from 0.1 mm to 20.0 mm are used to set the correct caliper, optionally using combinations of several shims.
- test cell (20220) is rotated 90° (sample is vertical) and the test liquid allowed to enter slowly from the bottom. This is necessary to ensure that all the air is driven out from the sample and the inlet/outlet connections (20232/20233).
- the test cell (20220) is rotated back to its original position so as to make the sample (20210) horizontal.
- the subsequent procedure is the same as that described earlier for transplanar permeability, i.e. the inlet reservoir is placed at the desired height, the flow is allowed to equilibrate, and flow rate and pressure drop are measured. Permeability is calculated using Darcy's law. This procedure is repeated for higher pressures as well.
- Optical determination of pore size is especially used for thin layers of porous system by using standard image analysis procedures know to the skilled artisan.
- a thin layer of the sample material is prepared by either slicing a thick sample into thinner sheets or if the sample itself is thin by using it directly.
- the term "thin” refers to achieving a sample caliper low enough to allow a clear cross-section image under the microscope. Typical sample calipers are below 200 ⁇ m.
- a microscopic image is obtained via a video microscope using the appropriate magnification. Best results are obtained if about 10 to 100 pores are visible on said image.
- the image is then digitized by a standard image analysis package such as OPTIMAS by BioScan Corp. which runs under Windows 95 on a typical IBM compatible PC.
- Frame grabber of sufficient pixel resolution should be used to obtain good results.
- the image is converted to a binary image using an appropriate threshold level such that the pores visable on the image are marked as object areas in white and the rest remains black. Automatic threshold setting procedures such as available under OPTIMAS can be used.
- the areas of the individual pores (objects) are determined. OPTIMAS offers fully automatic determination of the areas.
- the average pore size can then be determined from the pore size distribution using standard statistical rules. For materials that have a not very uniform pore size it is recommended to use at least 3 samples for the determination.
- test should be carried out with a suitable test fluid representing the transport fluid.
- a suitable test fluid representing the transport fluid.
- the formula for the synthetic urine is: 2.0 g/: of KCI; 2.0 g/l of Na2SO4; 0.85 g/l of (NH4)2HPO4; 0.15 g/l (NH4)H2PO4; 0.19 g/l of CaCI2; ad 0.23 g/l of MgCI2. All of the chemicals are of reagent grade.
- the pH of the synthetic Urine is in the range of 6.0 to 6.4.
- Test specimen are stored under these conditions for at least 24 hours before testing, and - if applicable - activated as described in the above.
- the present Permeability Test provides a measure for permeability for two special conditions: Either the permeability can be measured for a wide range of porous materials (such as non-wovens made of synthetic fibres, or cellulosic structures) at 100% saturation, or for materials, which reach different degrees of saturation with a proportional change in caliper without being filled with air (respectively the outside vapour phase), such as the collapsible polymeric foams, for which the permeability at varying degrees of saturation can readily be measured at various thicknesses.
- porous materials such as non-wovens made of synthetic fibres, or cellulosic structures
- permeability can be calculated - for a fixed or given sample cross- sectional area and test liquid viscosity - by measurement of pressure drop and the volumetric flow rate through the sample:
- the test can be executed in two modifications, the first referring to the transplanar permeability (i.e. the direction of flow is essentially along the thickness dimension of the material), the second being the in-plane permeability (i.e. the direction of flow being in the x-y-direction of the material).
- Figure 19 is a schematic diagram of the overall equipment and - as an insert diagram - a partly exploded cross-sectional, not to scale view of the sample cell.
- the test set-up comprises a generally circular or cylindrical sample cell (19120), having an upper (19121) and lower (19122) part. The distance of these parts can be measured and hence adjusted by means of each three circumferentially arranged caliper gauges (19145) and adjustment screws (19140). Further, the equipment comprises several fluid reservoirs (19150, 19154, 19156) including a height adjustment (19170) for the inlet reservoir (19150) as well as tubings (19180), quick release fittings (19189) for connecting the sample cell with the rest of the equipment, further valves (19182, 19184, 19186, 19188).
- the differential pressure transducer (19197) is connected via tubing (19180) to the upper pressure detection point (19194) and to the lower pressure detection point (19196).
- a Computer device (19190) for control of valves is further connected via connections (19199) to differential pressure transducer (19197), temperature probe (19192), and weight scale load cell (19198).
- the circular sample (19110) having a diameter of 1 in (about 2.54 cm) is placed in between two porous screens (19135) inside the sample cell (19120), which is made of two 1 in (2.54 cm) inner diameter cylindrical pieces (19121 , 19122) attached via the inlet connection (19132) to the inlet reservoir (19150) and via the outlet connection (19133) to the outlet reservoir (19154) by flexible tubing (19180), such as tygon tubing. Closed cell foam gaskets (19115) provide leakage protection around the sides of the sample.
- the test sample (19110) is compressed to the caliper corresponding to the desired wet compression, which is set to 0.2 psi (about 1.4 kPa) unless otherwise mentioned.
- Liquid is allowed to flow through the sample (19110) to achieve steady state flow.
- volumetric flow rate and pressure drop are recorded as a function of time using a load cell (19198) and the differential pressure transducer (19197).
- the experiment can be performed at any pressure head up to 80 cm water (about 7.8 kPa), which can be adjusted by the height adjusting device (19170). From these measurements, the flow rate at different pressures for the sample can be determined.
- the equipment is commercially available as a Permeameter such as supplied by Porous Materials, Inc, Ithaca, New York, US under the designation PMI Liquid Permeameter, such as further described in respective user manual of 2/97.
- This equipment includes two Stainless Steel Frits as porous screens (19135), also specified in said brochure.
- the equipment consists of the sample cell (19120), inlet reservoir (19150), outlet reservoir (19154), and waste reservoir (19156) and respective filling and emptying valves and connections, an electronic scale, and a computerized monitoring and valve control unit (19190).
- the gasket material (19115) is a Closed Cell Neoprene Sponge SNC-1
- Soft such as supplied by Netherland Rubber Company, Cincinnati, Ohio, US.
- a set of materials with varying thickness in steps of 1/16" (about 0.159 cm) should be available to cover the range from 1/16" -1/2" (about 0.159 cm to about 1.27 cm) thickness.
- a pressurized air supply is required, of at least 60 psi (4.1 bar), to operate the respective valves.
- Test fluid is deionized water.
- test it is determined, if one or more layers of the test sample are required, wherein the test as outlined below is run at the lowest and highest pressure. The number of layers is then adjusted so as to maintain the flow rate during the test between 0.5 cm 3 /seconds at the lowest pressure drop and 15 cm 3 /second at the highest pressure drop. The flow rate for the sample should be less than the flow rate for the blank at the same pressure drop. If the sample flow rate exceeds that of the blank for a given pressure drop, more layers should be added to decrease the flow rate.
- Sample size Samples are cut to 1" (about 2.54 cm) diameter, by using an arch punch, such as supplied by McMaster-Carr Supply Company, Cleveland,
- a conventional low basis weight support means can be added, such as a PET scrim or net.
- At least two samples are precut. Then, one of these is saturated in deionized water at the temperature the experiment is to be performed . (70° F, (31° C) unless otherwise noted).
- the caliper of the wet sample is measured (if necessary after a stabilization time of 30 seconds) under the desired compression pressure for which the experiment will be run by using a conventional caliper gauge (such as supplied by AMES, Waltham, MASS, US) having a pressure foot diameter of 1 1/8 " (about 2.86 cm), exerting a pressure of 0.2 psi (about 1.4 kPa) on the sample (19110), unless otherwise desired.
- gasketing foam (19115) is between 150 and 200% of the thickness of the wet sample (note that a combination of varying thicknesses of gasket material may be needed to achieve the overall desired thickness).
- the gasket material (19115) is cut to a circular size of 3" in diameter, and a 1 inch (2.54 cm) hole is cut into the center by using the arch punch.
- the sample should be cut such that the required diameter is taken in the wet stage. This can also be assessed in this preparatory test, with monitoring of the respective dimensions. If these change such that either a gap is formed, or the sample forms wrinkles which would prevent it from smoothly contacting the porous screens or frits, the cut diameter should be adjusted accordingly.
- test sample (19110) is placed inside the hole in the gasket foam (19115), and the composite is placed on top of the bottom half of the sample cell, ensuring that the sample is in flat, smooth contact with the screen (19135), and no gaps are formed at the sides.
- test cell (19121) The top of the test cell (19121) is laid flat on the lab bench (or another horizontal plane) and all three caliper gauges (19145) mounted thereon are zeroed.
- the top of the test cell (19121) is then placed onto the bottom part (19122) such that the gasket material(19115) with the test sample (19110) lays in between the two parts.
- the top and bottom part are then tightened by the fixation screws (19140), such that the three caliper gauges are adjusted to the same value as measured for the wet sample under the respective pressure in the above.
- sample cell (19120) is positioned into the permeameter unit with Quick Disconnect fittings (19189).
- the sample cell (19120) is filled by opening the vent valve (19188) and the bottom fill valves (19184, 19186). During this step, care must be taken to 5 remove air bubbles from the system, which can be achieved by turning the sample cell vertically, forcing air bubbles - if present - to exit the permeameter through the drain.
- the liquid outlet flow is automatically diverted from the waste reservoir (19156) to the outlet reservoir (19154), and pressure drop, and temperature are monitored as a function of time for several minutes.
- the computerized unit provides the recorded data (in numeric and/or graphical form). If desired, the same test sample can be used to measure the permeability at varying pressure heads, with thereby increasing the pressure from run to run.
- the equipment should be cleaned every two weeks, and calibrated at least once per week, especially the frits, the load cell, the thermocouple and the pressure transducer, thereby following the instructions of the equipment supplier.
- the differential pressure is recorded via the differential pressure transducer connected to the pressure probes measurement points (19194, 19196) in the top and bottom part of the sample cell. Since there may be other flow resistances within the chamber adding to the pressure that is recorded, each experiment must be corrected by a blank run. A blank run should be done at 10, 20, 30, 40, 50, 60, 70, 80 cm requested pressure, each day.
- the permeameter will output a Mean Test Pressure for each experiment and also an average flow rate.
- the flow rate is recorded as Blank Corrected Pressure by the computerized unit (19190), which is further correcting the Mean Test Pressure (Actual Pressure) at each height recorded pressure differentials to result in the Corrected Pressure.
- This Corrected Pressure is the DP that should be used in the permeability equation below.
- Permeability can then be calculated at each requested pressure and all permeabilities should be averaged to determine the k for the material being tested.
- the transplanar simplified sample cell (19120) of figure 19 is replaced by the in-plane simplified sample cell (20220), which is designed so that liquid can flow only in one direction (either machine direction or cross direction depending on how the sample is placed in the cell). Care should be taken to minimize channeling of liquid along the walls (wall effects), since this can erroneously give high permeability reading.
- the test procedure is then executed quite analogous to the transplanar simplified test.
- the sample cell (20220) is designed to be positioned into the equipment essentially as described for the sample cell (20120) in the above transplanar test, except that the filling tube is directed to the inlet connection (20232) the bottom of the cell (20220).
- Figure 20A shows a partly exploded view of the sample cell
- Figure 20B a cross-sectional view through the sample level.
- the test cell (20220) is made up of two pieces: a bottom piece (20225) which is like a rectangular box with flanges, and a top piece (20223) that fits inside the bottom piece (20225) and has flanges as well.
- the test sample is cut to the size of 2" in x 2"in (about 5.1 cm by 5.1 cm) and is placed into the bottom piece.
- the top piece (20223) of the sample chamber is then placed into the bottom piece (20225) and sits on the test sample (20210).
- An incompressible neoprene rubber seal (20224) is attached to the upper piece (20223) to provide tight sealing.
- the test liquid flows from the inlet reservoir to the sample space via Tygon tubing and the inlet connection (20232) further through the outlet connection (20233) to the outlet reservoir.
- the sample is kept at the desired test temperature by the heating device (20226), whereby thermostated water is pumped through the heating chamber (20227).
- the gap in the test cell is set at the caliper corresponding to the desired wet compression, normally 0.2 psi (about 1.4 kPa).
- Shims (20216) ranging in size from 0.1 mm to 20.0 mm and fixation screw (20240) are used to set the correct caliper, optionally using combinations of several shims.
- test cell (20220) is rotated 90° (sample is vertical) and the test liquid allowed to enter slowly from the bottom. This is necessary to ensure that all the air is driven out from the sample and the inlet/outlet connections (20232/20233).
- the test cell (20220) is rotated back to its original position so as to make the sample (20210) horizontal.
- the subsequent procedure is the same as that described earlier for transplanar permeability, i.e. the inlet reservoir is placed at the desired height, the flow is allowed to equilibrate, and flow rate and pressure drop are measured. Permeability is calculated using Darcy's law. This procedure is repeated for higher pressures as well.
- the demand absorbency test is intended to measure the liquid capacity of liquid handling member and to measure the absorption speed of liquid handling member against zero hydrostatic pressure.
- the test may also be carried out for devices for managing body liquids containing a liquid handling member.
- the apparatus used to conduct this test consists of a square basket of a sufficient size to hold the liquid handling member suspended on a frame. At least the lower plane of the square basket consists of an open mesh that allows liquid penetration into the basket without substantial flow resistance for the liquid uptake.
- an open wire mesh made of stainless steel having an open area of at least 70 percent and having a wire diameter of 1mm, and an open mesh size of at about 6mm is suitable for the setup of the present test.
- the open mesh should exhibit sufficient stability such that it substantially does not deform under load of the test specimen when the test specimen is filled up to its full capacity.
- a liquid reservoir is provided below the basket.
- the height of the basket can be adjusted so that a test specimen which is placed inside the basket may be brought into contact with the surface of the liquid in the liquid reservoir.
- the liquid reservoir is placed on the electronic balance connected to a computer to read out the weight of the liquid about every 0.01 sec during the measurement.
- the dimensions of the apparatus are chosen such that the liquid handling member to be tested fits into the basket and such that the intended liquid acquisition zone of the liquid handing member is in contact with the lower plane of the basket.
- the dimensions of the liquid reservoir are chosen such that the level of the liquid surface in the reservoir does not substantially change during the measurement.
- a typical reservoir useful for testing liquid handling members has a size of at least 320 mm x 370 mm and can hold at least about 4500 g of liquid.
- the liquid reservoir is filled with synthetic urine. The amount of synthetic urine and the size of the liquid reservoir should be sufficient such that the liquid level in the reservoir does not change when the liquid capacity of the liquid handing member to be tested is removed from the reservoir.
- the temperature of the liquid and the environment for the test should reflect in-use conditions of the member. Typical temperature for use in baby diapers are 32 degrees Celsius for the environment and 37 degrees Celsius for the synthetic urine. The test may be done at room temperature if the member tested has no significant dependence of its absorbent properties on temperature.
- the test is setup by lowering the empty basket until the mesh is just completely immersed in the synthetic urine in the reservoir.
- the basket is then raised again by about 0.5 to 1mm in order to establish an almost zero hydrostatic suction, care should be taken that the liquid stays in contact with the mesh. If necessary, the mesh needs to be brought back into contact with the liquid and zero level be readjusted.
- the test is started by:
- the Teabag Centrifuge Capacity test measures the Teabag Centrifuge
- Capacity values which are a measure of the retention of liquids in the absorbent materials.
- the absorbent material is placed within a "teabag", immersed in a 0.9% by weight sodium chloride solution for 20 minutes, and then centrifuged for 3 minutes.
- the ratio of the retained liquid weight to the initial weight of the dry material is the absorptive capacity of the absorbent material.
- the teabag pouch has dimensions 6.5 cm x 6.5 cm and is available from
- the pouch is heat sealable with a standard kitchen plastic bag sealing device (e.g. VACUPACK2 PLUS from Krups,
- the teabag is opened by carefully cutting it partially, and is then weighed. About 0.200g of the sample of the absorbent material, accurately weighed to +/-
- sample teabag An empty teabag is sealed and used as a blank.
- the sample teabag and the blank teabag are then laid on the surface of the saline solution, and submerged for about 5 seconds using a spatula to allow complete wetting (the teabags will float on the surface of the saline solution but are then completely wetted). The timer is started immediately.
- the sample teabag and the blank teabag are removed from the saline solution, and placed in a Bauknecht WS130, Bosch 772 NZK096 or equivalent centrifuge (230 mm diameter), so that each bag sticks to the outer wall of the centrifuge basket.
- the centrifuge lid is closed, the centrifuge is started, and the speed increased quickly to 1 ,400 rpm. Once the centrifuge has been stabilised at 1 ,400 rpm the timer is started. After 3 minutes, the centrifuge is stopped. The sample teabag and the blank teabag are removed and weighed separately.
- TCC Teabag Centrifuge Capacity
- TCC [(sample teabag weight after centrifuging) - (blank teabag weight after centrifuging) - (dry absorbent material weight)] ⁇ (dry absorbent material weight).
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- Biomedical Technology (AREA)
- Heart & Thoracic Surgery (AREA)
- Vascular Medicine (AREA)
- Animal Behavior & Ethology (AREA)
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- Absorbent Articles And Supports Therefor (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Laminated Bodies (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Investigating Or Analysing Biological Materials (AREA)
- Sampling And Sample Adjustment (AREA)
- Containers And Packaging Bodies Having A Special Means To Remove Contents (AREA)
- Cleaning Implements For Floors, Carpets, Furniture, Walls, And The Like (AREA)
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Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP99933618A EP1119327A2 (en) | 1998-06-29 | 1999-06-29 | High flux liquid transport members comprising two different permeability regions |
AU49638/99A AU4963899A (en) | 1998-06-29 | 1999-06-29 | High flux liquid transport members comprising two different permeability regions |
US09/720,186 US6673057B1 (en) | 1998-06-29 | 1999-06-29 | High flux liquid transport members comprising two different permeability regions |
JP2000556732A JP2003527249A (en) | 1998-06-29 | 1999-06-29 | High flux liquid transport member with two different permeability regions |
CA002336019A CA2336019C (en) | 1998-06-29 | 1999-06-29 | High flux liquid transport members comprising two different permeability regions |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
USPCT/US98/13449 | 1998-06-29 | ||
PCT/US1998/013449 WO2000000127A1 (en) | 1998-06-29 | 1998-06-29 | High flux liquid transport members comprising two different permeability regions |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2000000146A2 true WO2000000146A2 (en) | 2000-01-06 |
WO2000000146A3 WO2000000146A3 (en) | 2001-05-25 |
Family
ID=22267389
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1998/013449 WO2000000127A1 (en) | 1998-06-29 | 1998-06-29 | High flux liquid transport members comprising two different permeability regions |
PCT/US1999/014796 WO2000000146A2 (en) | 1998-06-29 | 1999-06-29 | High flux liquid transport members comprising two different permeability regions |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1998/013449 WO2000000127A1 (en) | 1998-06-29 | 1998-06-29 | High flux liquid transport members comprising two different permeability regions |
Country Status (8)
Country | Link |
---|---|
EP (1) | EP1119327A2 (en) |
JP (5) | JP2003523779A (en) |
AR (1) | AR017489A1 (en) |
AT (1) | ATE242621T1 (en) |
AU (2) | AU8271698A (en) |
CA (12) | CA2335625A1 (en) |
PE (1) | PE20000732A1 (en) |
WO (2) | WO2000000127A1 (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6659992B1 (en) | 1998-06-29 | 2003-12-09 | The Procter & Gamble Company | Absorbent article instanteously storing liquid in a predefined pattern |
US6764476B1 (en) | 1998-06-29 | 2004-07-20 | The Procter & Gamble Company | Absorbent article comprising a liquid handling member that rapidly distributes acquired liquid |
US6849065B2 (en) | 1999-12-23 | 2005-02-01 | The Procter & Gamble Company | Liquid removal system having improved dryness of the user facing surface |
US6932797B2 (en) | 1999-12-23 | 2005-08-23 | The Procter & Gamble Company | Liquid removal system which is compressible in the longitudinal and/or in the transverse direction |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
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US7799967B2 (en) | 2004-04-08 | 2010-09-21 | Kimberly-Clark Worldwide, Inc. | Differentially expanding absorbent structure |
CN101257875A (en) | 2005-09-06 | 2008-09-03 | 泰科保健集团有限合伙公司 | Self contained wound dressing with micropump |
WO2013007973A2 (en) | 2011-07-14 | 2013-01-17 | Smith & Nephew Plc | Wound dressing and method of treatment |
EP3650055A1 (en) | 2012-05-23 | 2020-05-13 | Smith & Nephew plc | Apparatuses and methods for negative pressure wound therapy |
DK2879636T3 (en) | 2012-08-01 | 2017-06-19 | Smith & Nephew | Wound dressing |
EP2879635A2 (en) | 2012-08-01 | 2015-06-10 | Smith & Nephew PLC | Wound dressing and method of treatment |
CA2952284C (en) | 2014-06-18 | 2023-03-28 | Smith & Nephew Plc | Wound dressing |
FI128507B (en) * | 2016-06-20 | 2020-06-30 | Mikkelin Ammattikorkeakoulu Oy | Method and device for determining the degree of grinding of a fibre suspension |
GB2555584B (en) | 2016-10-28 | 2020-05-27 | Smith & Nephew | Multi-layered wound dressing and method of manufacture |
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US5387207A (en) | 1991-08-12 | 1995-02-07 | The Procter & Gamble Company | Thin-unit-wet absorbent foam materials for aqueous body fluids and process for making same |
US5563179A (en) | 1995-01-10 | 1996-10-08 | The Proctor & Gamble Company | Absorbent foams made from high internal phase emulsions useful for acquiring and distributing aqueous fluids |
EP0810078A1 (en) | 1996-05-28 | 1997-12-03 | The Procter & Gamble Company | Method for making fluid distribution materials |
WO1997047375A1 (en) | 1996-06-10 | 1997-12-18 | Usf Rossmark Waterbehandeling B.V. | Membrane filter system and pressure vessel suitable for membrane filtration |
US5728292A (en) | 1993-11-11 | 1998-03-17 | Nissan Motor Co., Ltd. | Filter for in-tank fuel pump |
US5733581A (en) | 1995-05-02 | 1998-03-31 | Memtec America Corporation | Apparatus for making melt-blown filtration media having integrally co-located support and filtration fibers |
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US4676785A (en) * | 1985-10-21 | 1987-06-30 | Battista Orlando A | Liquid retaining absorbent structure |
US4988235A (en) | 1988-04-27 | 1991-01-29 | Dennis Hurley | System for draining land areas through siphoning from a permeable catch basin |
US5078709A (en) * | 1988-04-29 | 1992-01-07 | Evaporating Apparel Industries | Evaporating attachment means suitable for containing and draining fluids emanating from a subject |
ZA903296B (en) * | 1989-05-26 | 1991-02-27 | Kimerly Clark Corp | Vertical wicking structures from wet crosslinked cellulose fiber structures |
US5498252A (en) * | 1993-01-11 | 1996-03-12 | Silber; Arthur L. | Toxicity resistant, self-fitting and adjustable, self-closing tampon structure |
US5650222A (en) * | 1995-01-10 | 1997-07-22 | The Procter & Gamble Company | Absorbent foam materials for aqueous fluids made from high internal phase emulsions having very high water-to-oil ratios |
US6060638A (en) * | 1995-12-22 | 2000-05-09 | Kimberly-Clark Worldwide, Inc. | Matched permeability liner/absorbent structure system for absorbent articles and the like |
US6372952B1 (en) * | 1996-03-22 | 2002-04-16 | The Procter & Gamble Company | Absorbent components having a sustained acquisition rate capability upon absorbing multiple discharges of aqueous body fluids |
SE506744C2 (en) | 1996-03-22 | 1998-02-09 | Alfa Laval Ab | Filter unit for rotating disk filter and method for its manufacture |
US5769834A (en) * | 1996-11-18 | 1998-06-23 | The Procter & Gamble Company | Absorbent article having a fluid pumping element |
US5820973A (en) * | 1996-11-22 | 1998-10-13 | Kimberly-Clark Worldwide, Inc. | Heterogeneous surge material for absorbent articles |
US5843063A (en) * | 1996-11-22 | 1998-12-01 | Kimberly-Clark Worldwide, Inc. | Multifunctional absorbent material and products made therefrom |
-
1998
- 1998-06-29 WO PCT/US1998/013449 patent/WO2000000127A1/en active Application Filing
- 1998-06-29 AU AU82716/98A patent/AU8271698A/en not_active Abandoned
-
1999
- 1999-06-29 CA CA002335625A patent/CA2335625A1/en not_active Abandoned
- 1999-06-29 CA CA002333765A patent/CA2333765A1/en not_active Abandoned
- 1999-06-29 JP JP2000556727A patent/JP2003523779A/en active Pending
- 1999-06-29 CA CA002334180A patent/CA2334180A1/en not_active Abandoned
- 1999-06-29 CA CA002335589A patent/CA2335589A1/en not_active Abandoned
- 1999-06-29 CA CA002335639A patent/CA2335639A1/en not_active Abandoned
- 1999-06-29 CA CA002336019A patent/CA2336019C/en not_active Expired - Fee Related
- 1999-06-29 CA CA002334162A patent/CA2334162A1/en not_active Abandoned
- 1999-06-29 CA CA002333760A patent/CA2333760C/en not_active Expired - Fee Related
- 1999-06-29 WO PCT/US1999/014796 patent/WO2000000146A2/en not_active Application Discontinuation
- 1999-06-29 CA CA002334158A patent/CA2334158C/en not_active Expired - Fee Related
- 1999-06-29 EP EP99933618A patent/EP1119327A2/en not_active Withdrawn
- 1999-06-29 AU AU49638/99A patent/AU4963899A/en not_active Abandoned
- 1999-06-29 JP JP2000556971A patent/JP2003523894A/en not_active Withdrawn
- 1999-06-29 AT AT99932014T patent/ATE242621T1/en not_active IP Right Cessation
- 1999-06-29 CA CA002333697A patent/CA2333697C/en not_active Expired - Fee Related
- 1999-06-29 CA CA002333719A patent/CA2333719C/en not_active Expired - Fee Related
- 1999-06-29 CA CA002335622A patent/CA2335622A1/en not_active Abandoned
- 1999-06-29 JP JP2000556864A patent/JP2003523840A/en not_active Withdrawn
- 1999-06-29 JP JP2000556732A patent/JP2003527249A/en active Pending
- 1999-06-29 JP JP2000556726A patent/JP2003523778A/en active Pending
- 1999-06-30 PE PE1999000586A patent/PE20000732A1/en not_active Application Discontinuation
- 1999-07-29 AR ARP990103164A patent/AR017489A1/en unknown
Patent Citations (6)
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US5387207A (en) | 1991-08-12 | 1995-02-07 | The Procter & Gamble Company | Thin-unit-wet absorbent foam materials for aqueous body fluids and process for making same |
US5728292A (en) | 1993-11-11 | 1998-03-17 | Nissan Motor Co., Ltd. | Filter for in-tank fuel pump |
US5563179A (en) | 1995-01-10 | 1996-10-08 | The Proctor & Gamble Company | Absorbent foams made from high internal phase emulsions useful for acquiring and distributing aqueous fluids |
US5733581A (en) | 1995-05-02 | 1998-03-31 | Memtec America Corporation | Apparatus for making melt-blown filtration media having integrally co-located support and filtration fibers |
EP0810078A1 (en) | 1996-05-28 | 1997-12-03 | The Procter & Gamble Company | Method for making fluid distribution materials |
WO1997047375A1 (en) | 1996-06-10 | 1997-12-18 | Usf Rossmark Waterbehandeling B.V. | Membrane filter system and pressure vessel suitable for membrane filtration |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6659992B1 (en) | 1998-06-29 | 2003-12-09 | The Procter & Gamble Company | Absorbent article instanteously storing liquid in a predefined pattern |
US6764476B1 (en) | 1998-06-29 | 2004-07-20 | The Procter & Gamble Company | Absorbent article comprising a liquid handling member that rapidly distributes acquired liquid |
US6849065B2 (en) | 1999-12-23 | 2005-02-01 | The Procter & Gamble Company | Liquid removal system having improved dryness of the user facing surface |
US6932797B2 (en) | 1999-12-23 | 2005-08-23 | The Procter & Gamble Company | Liquid removal system which is compressible in the longitudinal and/or in the transverse direction |
Also Published As
Publication number | Publication date |
---|---|
WO2000000127A1 (en) | 2000-01-06 |
CA2333719A1 (en) | 2000-01-06 |
CA2334180A1 (en) | 2000-01-06 |
JP2003523779A (en) | 2003-08-12 |
CA2335622A1 (en) | 2000-01-06 |
AU8271698A (en) | 2000-01-17 |
AR017489A1 (en) | 2001-09-05 |
CA2333719C (en) | 2007-04-03 |
ATE242621T1 (en) | 2003-06-15 |
EP1119327A2 (en) | 2001-08-01 |
PE20000732A1 (en) | 2000-10-20 |
CA2333697C (en) | 2006-10-03 |
AU4963899A (en) | 2000-01-17 |
CA2334158C (en) | 2007-02-13 |
CA2334162A1 (en) | 2000-01-06 |
CA2336019A1 (en) | 2000-01-06 |
CA2333697A1 (en) | 2000-01-06 |
JP2003523894A (en) | 2003-08-12 |
CA2336019C (en) | 2005-07-05 |
CA2335639A1 (en) | 2000-01-06 |
JP2003523840A (en) | 2003-08-12 |
WO2000000146A3 (en) | 2001-05-25 |
JP2003527249A (en) | 2003-09-16 |
CA2334158A1 (en) | 2000-01-06 |
JP2003523778A (en) | 2003-08-12 |
CA2335589A1 (en) | 2000-01-06 |
CA2333765A1 (en) | 2000-01-06 |
CA2335625A1 (en) | 2000-01-06 |
CA2333760C (en) | 2005-02-08 |
CA2333760A1 (en) | 2000-01-06 |
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