US20150275419A1

US20150275419A1 - Tissue-based water barrier material

Info

Publication number: US20150275419A1
Application number: US14/231,322
Authority: US
Inventors: Maria del Carmen Lopez Garcia; Sridhar Ranganathan
Original assignee: Kimberly Clark Worldwide Inc
Current assignee: Kimberly Clark Worldwide Inc
Priority date: 2014-03-31
Filing date: 2014-03-31
Publication date: 2015-10-01

Abstract

A hydrophobic, liquid-impermeable substrate includes a hydrophilic nonwoven having a treated surface, a polyolefin dispersion disposed on the treated surface, and a hydrophobic chemistry disposed on the polyolefin dispersion. A method for preparing a hydrophobic, breathable, liquid-impermeable substrate includes providing a hydrophilic nonwoven having a treated surface, applying a polyolefin dispersion to the treated surface, and applying a hydrophobic chemistry to the polyolefin dispersion. The hydrophilic nonwoven can be tissue or paper toweling. The hydrophobic chemistry can be a water-dispersible hydrophobic polymer.

Description

BACKGROUND

The present disclosure relates to hydrophilic, breathable materials that exhibit hydrophobic properties when treated with certain compositions. Currently, hydrophobic, breathable materials are generally made using hydrophobic polymeric films or fiber webs. Such materials tend to be hydrophobic throughout the thickness of the material, which might not be desired in many cases. Such materials also tend to be less cost effective. Although various formulated dispersions capable of coating a surface to make that surface hydrophobic exist, these tend not to be water-based. These tend to require the use of organic solvents.
Disposable absorbent products (e.g., diapers, feminine hygiene products, incontinence products, etc.) are subjected to one or more liquid insults, such as of water, urine, menses, or blood, during use. Many commercially available diapers allow water vapor to pass through the diaper and into the environment to lessen the humidity in the micro-climate between the product and the wearer's skin and reduce the chance of skin irritation and rash due to skin overhydration. To allow the passage of vapor out of the diaper and into the environment while holding liquid within, a “breathable” outer cover is often employed that is formed from a nonwoven web laminated to a vapor-permeable film.

SUMMARY

As a result, a new material is needed that is both cost-effective and does not rely on organic solvents. The present disclosure relates to the use of a hydrophobic chemistry applied to a hydrophilic fibrous material to create liquid barrier properties in an otherwise wettable nonwoven. This yields a hydrophilic substrate that acts like a film while still being air permeable and exceeding the breathability seen in standard breathable outer cover films.
Presented is a hydrophobic, liquid-impermeable substrate including a hydrophilic nonwoven having a treated surface, a polyolefin dispersion disposed on the treated surface, and a hydrophobic chemistry disposed on the polyolefin dispersion. The hydrophilic nonwoven can be tissue or paper toweling. The hydrophobic chemistry can be a water-dispersible hydrophobic polymer.
In another aspect, a method for preparing a hydrophobic, breathable, liquid-impermeable substrate includes providing a hydrophilic nonwoven having a treated surface, applying a polyolefin dispersion to the treated surface, and applying a hydrophobic chemistry to the polyolefin dispersion.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing and other features and aspects of the present disclosure and the manner of attaining them will become more apparent, and the disclosure itself will be better understood by reference to the following description, appended claims and accompanying drawings, where:

FIG. 1 illustrates hydrohead behavior for Substrate A and Substrate B as a function of increasing add-on amounts of hydrophobic chemistries;

FIG. 2 illustrates hydrohead behavior for sized handsheets. Note that lines are not a mathematical trend but are included to show a general behavior;

FIG. 3 illustrates the behavior of Substrate B with a HYPOD polyolefin dispersion and hydrophobic chemistries in the functional water barrier test;

FIG. 4 illustrates the behavior of Substrate A with a HYPOD polyolefin dispersion and hydrophobic chemistries in the functional water barrier test;

FIG. 5 illustrates leakage from handsheets in a functional water barrier test. The hydrophobic add-ons were approximately 0.1 gsm for nanoclay and 2 gsm for the UNIDYNE KCO3 fluorinated water and oil repellent. Note that the lines are not mathematical trends;

FIG. 6 illustrates the air permeability of various basesheets. The air permeability of an ASFL outer cover is zero;

FIG. 7 illustrates hydrohead versus leakage. Hydrohead is in centimeters of water and leakage is in grams from the functional water barrier test (FWBT). The FWBT was performed with 0.2 psi, 90% core capacity, and a one-minute wait before applying pressure;

FIG. 8 illustrates hydrohead versus air permeability; and

FIG. 9 illustrates the test apparatus for measuring hydrohead values.

Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present disclosure. The drawings are representational and are not necessarily drawn to scale. Certain proportions thereof might be exaggerated, while others might be minimized.

DETAILED DESCRIPTION

All percentages are by weight of the total composition unless specifically stated otherwise. All ratios are weight ratios unless specifically stated otherwise.
The term “hydrophobic,” as used herein, refers to the property of a surface to repel water with a water contact angle greater than about 90°.
The term “superhydrophobic” refers to the property of a surface to repel water very effectively. This property is quantified by a water contact angle generally exceeding 150°.
The term “hydrophilic,” as used herein, refers to surfaces with water contact angles well below 90°.
As used herein, the term “breathability” refers to the water vapor transmission rate (WVTR) of an area of film. Breathability is measured in grams of water per square meter per day. For purposes of the present disclosure, a film is “breathable” if it has a WVTR of at least 800 grams per square meter per 24 hours as calculated using the MOCON test method, which is described in detail below.
As used herein, the term “nonwoven web” or “nonwoven fabric” means a web having a structure of individual fibers or threads that are interlaid, but not in an identifiable manner as in a knitted web. Nonwoven webs have been formed from many processes, such as, for example, meltblowing processes, spunbonding processes, air-laying processes, coforming processes, bonded carded web processes, and tissue and towel manufacturing processes. The basis weight of nonwoven webs is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters are usually expressed in microns, or in the case of staple fibers, in denier. It is noted that to convert from osy to gsm, multiply osy by 33.91.
As used herein the term “spunbond fibers” refers to small diameter fibers of molecularly oriented polymeric material. Spunbond fibers can be formed by extruding molten thermoplastic material as fibers from a plurality of fine, usually circular capillaries of a spinneret with the diameter of the extruded fibers then being rapidly reduced as in, for example, U.S. Pat. No. 4,340,563 to Appel et al., and U.S. Pat. No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to Matsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney, U.S. Pat. No. 3,502,763 to Hartman, U.S. Pat. No. 3,542,615 to Dobo et al, and U.S. Pat. No. 5,382,400 to Pike et al. Spunbond fibers are generally not tacky when they are deposited onto a collecting surface and are generally continuous. Spunbond fibers are often about 10 microns or greater in diameter. However, fine fiber spunbond webs (having an average fiber diameter less than about 10 microns) can be achieved by various methods including, but not limited to, those described in commonly assigned U.S. Pat. No. 6,200,669 to Marmon et al. and U.S. Pat. No. 5,759,926 to Pike et al.
Meltblown nonwoven webs are prepared from meltblown fibers. As used herein the term “meltblown fibers” means fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity, usually hot, gas (e.g. air) streams that attenuate the filaments of molten thermoplastic material to reduce their diameter, which can be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly dispersed meltblown fibers. Such a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to Buntin. Meltblown fibers are microfibers that can be continuous or discontinuous, are generally smaller than 10 microns in average diameter (using a sample size of at least 10), and are generally tacky when deposited onto a collecting surface.
As used herein, the term “polymer” generally includes, but is not limited to, homopolymers, copolymers, such as for example, block, graft, random and alternating copolymers, terpolymers, etc. and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term “polymer” shall include all possible geometrical configurations of the molecule. These configurations include, but are not limited to isotactic, syndiotactic and random symmetries.
As used herein, the term “multicomponent fibers” refers to fibers or filaments that have been formed from at least two polymers extruded from separate extruders but spun together to form one fiber. Multicomponent fibers are also sometimes referred to as “conjugate” or “bicomponent” fibers or filaments. The term “bicomponent” means that there are two polymeric components making up the fibers. The polymers are usually different from each other, although conjugate fibers can be prepared from the same polymer, if the polymer in each component is different from one another in some physical property, such as, for example, melting point, glass transition temperature or the softening point. In all cases, the polymers are arranged in substantially constantly positioned distinct zones across the cross-section of the multicomponent fibers or filaments and extend continuously along the length of the multicomponent fibers or filaments. The configuration of such a multicomponent fiber can be, for example, a sheath/core arrangement, wherein one polymer is surrounded by another, a side-by-side arrangement, a pie arrangement or an “islands-in-the-sea” arrangement. Multicomponent fibers are taught in U.S. Pat. No. 5,108,820 to Kaneko et al.; U.S. Pat. No. 5,336,552 to Strack et al.; and U.S. Pat. No. 5,382,400 to Pike et al. For two component fibers or filaments, the polymers can be present in ratios of 75/25, 50/50, 25/75 or any other desired ratios.
As used herein, the term “multiconstituent fibers” refers to fibers that have been formed from at least two polymers extruded from the same extruder as a blend or mixture. Multiconstituent fibers do not have the various polymer components arranged in relatively constantly positioned distinct zones across the cross-sectional area of the fiber and the various polymers are usually not continuous along the entire length of the fiber, instead usually forming fibrils or protofibrils that start and end at random. Fibers of this general type are discussed in, for example, U.S. Pat. Nos. 5,108,827 and 5,294,482 to Gessner.
As used herein, the term “substantially continuous fibers” is intended to mean fiber that have a length that is greater that the length of staple fibers. The term is intended to include fibers that are continuous, such as spunbond fibers, and fibers that are not continuous, but have a defined length greater than about 150 millimeters.
As used herein, the term “staple fibers” means fibers that have a fiber length generally in the range of about 0.5 to about 150 millimeters. Staple fibers can be cellulosic fibers or non-cellulosic fibers. Some examples of suitable non-cellulosic fibers that can be used include, but are not limited to, polyolefin fibers, polyester fibers, nylon fibers, polyvinyl acetate fibers, and mixtures thereof. Cellulosic staple fibers include for example, pulp, thermomechanical pulp, synthetic cellulosic fibers, modified cellulosic fibers, and the like. Cellulosic fibers can be obtained from secondary or recycled sources. Some examples of suitable cellulosic fiber sources include virgin wood fibers, such as thermomechanical, bleached and unbleached softwood and hardwood pulps. Secondary or recycled cellulosic fibers can be obtained from office waste, newsprint, brown paper stock, paperboard scrap, etc., can also be used. Further, vegetable fibers, such as abaca, flax, milkweed, cotton, modified cotton, cotton linters, can also be used as the cellulosic fibers. In addition, synthetic cellulosic fibers such as, for example, rayon and viscose rayon can be used. Modified cellulosic fibers are generally are composed of derivatives of cellulose formed by substitution of appropriate radicals (e.g., carboxyl, alkyl, acetate, nitrate, etc.) for hydroxyl groups along the carbon chain.
As used herein, the term “pulp” refers to fibers from natural sources such as woody and non-woody plants. Woody plants include, for example, deciduous and coniferous trees. Non-woody plants include, for example, cotton, flax, esparto grass, milkweed, straw, jute, hemp, and bagasse.
As used herein, “tissue products” are meant to include facial tissue, bath tissue, towels, hankies, napkins and the like. The present disclosure is useful with tissue products and tissue paper in general, including but not limited to conventionally felt-pressed tissue paper, high bulk pattern densified tissue paper, and high bulk, uncompacted tissue paper.
The present disclosure relates to a surface of a hydrophilic substrate, or the substrate itself, exhibiting hydrophobic characteristics when treated with certain compositions. The hydrophobicity can be applied either over the entire surface, patterned throughout or on the substrate material, and/or directly penetrated through the z-directional thickness of the substrate material.
Materials such as diaper outercover spunbond-film laminate or surgical gown SMS are currently used to prevent liquid from penetrating through the material and onto the user or into the user's environment. These materials use film or meltblown made from hydrophobic polymers as barrier materials to prevent fluid penetration. On the other hand, many hydrophilic materials are currently used in various applications, the materials including those such as coform and HYDROKNIT brand towel (available from Kimberly-Clark) for wipes as well as cellulosic tissues for facial and bath tissues. These materials are absorptive and thus not useful as barriers to aqueous fluids. Tissue-based materials tend to be less expensive than polymeric laminates and films. Therefore, it would be desirable to use these as barrier materials if adequate function can be engineered.
The primary functions of a diaper outer cover are to isolate the contents of the inside of a diaper (e.g. body fluids) from the environment and to keep the entire product together over its useful life through disposal. Film-based substrates have been the choice historically because they can achieve this function at a low cost with a widely available material—polyethylene film. Over time, several features have been added to the outer cover including breathability (for skin health), cloth-like feel (tactile consumer benefit) and graphics (visual consumer aesthetics). This has necessitated an increase in base cost of the outer cover due to additional materials, process steps, and handling requirements. The materials described herein chooses a different starting point—a porous tissue-based substrate—to study the possibility of producing a material with a barrier function while maintaining breathability and not significantly increasing cost. In addition, tissue might be more widely available, particularly globally. This disclosure focuses on the outer cover portion of a diaper, and how to develop tissue that provides a water barrier such that it can function as an outer cover. Tissue is typically a highly absorbent, highly porous material that is unusable as a water barrier.
Three basic aspects of functionality that are important to understand and influence are 1) breathability—greater than a threshold vapor permeability; 2) liquid barrier—resistant to liquid transfer from a saturated absorbent; and 3) durability—abrasion and poke-through resistance.
The durability requirement stems from the need to keep the product contents together through the life of the article. The most stringent requirements likely are when the absorbent is saturated and the outer cover is subjected to deformation in use. Breathability is likely not an issue with this approach except that it can be too high such that there is a damp feel. Prior work has described how to mitigate this effect, see U.S. Pat. No. 6,369,292, which is incorporated herein by reference to the extent is does not conflict herewith. Liquid barrier is a challenge that is particularly tough for this approach because the starting point is a porous material that can be naturally hydrophilic. Surface energetics and pore size need to be controlled to ensure that the fabric has sufficient fluid transfer resistance.
Barrier performance with air permeability can be accomplished by coating a hydrophilic, fibrous substrate with both a polyolefin dispersion and a hydrophobic component. It was found that a combination of two treatments provided the desired benefits on a tissue/towel-based substrate. The best performance observed was the use of Substrate A, a double recreped tissue with printed latex and creped on both sides as described in U.S. Pat. No. 6,277,241, which is incorporated herein by reference to the extent it does not conflict herewith, and sold commercially as SCOTT brand scrub cloths. Substrate B is an UCTAD tissue with printed latex and creped on one side as described in U.S. Pat. No. 7,462,258, which is incorporated herein by reference to the extent it does not conflict herewith, and sold commercially as VIVA brand paper towels.
The first step is coating the substrate with a polyolefin dispersion such as a polyethylene copolymer dispersion commercially available as HYPOD 8510 from Dow Chemical, Freeport, Tex., U.S.A., as described in more detail below. This can be done via standard application methods including spray/crepe and foam/crepe processes such as those described in U.S. Patent Publication Nos. US20070137810, US20070137809, and US20120160400, and in U.S. patent application Ser. No. 13/905,429, each of which is incorporated herein by reference to the extent it does not conflict herewith. Uniformity of this coating step is important to ensure uniformity of the subsequent treatment in the second step.
The second step is coating the polymeric-dispersion treated substrate with a hydrophobic chemistry, as described in more detail below. Such hydrophobic chemistries can include Daikin UNIDYNE KCO3 fluorinated water and oil repellent, Formulation III, or Formulation V described below. UNIDYNE KCO3 fluorinated water and oil repellent is a chemical produced by Daikin America. Formulation III is 5 percent PMC, a 20 wt. % dispersion of a fluorinated ethylene-acrylic copolymer in water, as obtained from DUPONT (trade name CAPSTONE ST-100), and 95 percent water. Formulation V is PMC, water, and a hydrophilic nano-structured filler (NANOMER brand PGV nanoclay from Sigma Aldrich), which is a bentonite clay without organic modification. In Formulation V, the hydrophilic nanoclay is added to water and is sonicated until a stable suspension is produced. Formulations III and V are further described in U.S. patent application Ser. No. 13/193,065, which is incorporated herein by reference to the extent it does not conflict herewith.
The approach that was taken in this work was to experiment with additives and treatments that have been used previously to impart water barriers. The additives used were various sizing chemistries that tend to make the bulk hydrophobic. To provide a barrier function, only the surface of a substrate needs to be hydrophobic. As a result, the bulk approach is inefficient in terms of the level of chemistry added. However, additives in the wet end are easy to incorporate compared to surface treatments. The treatments used include a polyolefin dispersion applied using creping and several hydrophobic treatments that were applied by spray. Both the additive and treatment approaches rely on creating hydrophobic surfaces in the substrate. These need to be complemented with small pore size within the substrate as well to maintain good barrier. Sheet density and size of fibers used to form the substrate, for example, are well known ways to control pore size.
Several examples are detailed herein, leading to the conclusion that the combination of the polyolefin dispersion and hydrophobic treatments yields unexpected benefits, where one or the other treatment alone does not provide the desired benefits.
Suitable substrates of the present disclosure can include a nonwoven fabric, woven fabric, knit fabric, or laminates of these materials, to include a tissue or towel, as described herein. Materials and processes suitable for forming such substrate are generally well known to those skilled in the art. For instance, some examples of nonwoven fabrics that can be used in the present disclosure include, but are not limited to, spunbonded webs, meltblown webs, bonded carded webs, air-laid webs, coform webs, spunlace nonwoven web, hydraulically entangled webs, and the like. In each case, at least one of the fibers used to prepare the nonwoven fabric is a thermoplastic material containing fiber. In addition, nonwoven fabrics can be a combination of thermoplastic fibers and natural fibers, such as, for example, cellulosic fibers (softwood pulp, hardwood pulp, thermomechanical pulp, etc.). Generally, from the standpoint of cost and desired properties, the substrate of the present disclosure is a hydrophilic nonwoven fabric.
If desired, the nonwoven fabric can also be bonded using techniques well known in the art to improve the durability, strength, hand, aesthetics, texture, and/or other properties of the fabric. For instance, the nonwoven fabric can be thermally (e.g., pattern bonded, through-air dried), ultrasonically, adhesively and/or mechanically (e.g. needled) bonded. For instance, various pattern bonding techniques are described in U.S. Pat. No. 3,855,046 to Hansen; U.S. Pat. No. 5,620,779 to Levy, et al.; U.S. Pat. No. 5,962,112 to Haynes, et al.; U.S. Pat. No. 6,093,665 to Sayovitz, et al.; U.S. Design Pat. No. 428,267 to Romano, et al.; and U.S. Design Pat. No. 390,708 to Brown.
In another aspect, the substrate of the present disclosure is formed from a spunbonded web containing monocomponent and/or multicomponent fibers. Multicomponent fibers are fibers that have been formed from at least two polymer components. Such fibers are usually extruded from separate extruders but spun together to form one fiber. The polymers of the respective components are usually different from each other although multicomponent fibers can include separate components of similar or identical polymeric materials. The individual components are typically arranged in substantially constantly positioned distinct zones across the cross-section of the fiber and extend substantially along the entire length of the fiber. The configuration of such fibers can be, for example, a side-by-side arrangement, a pie arrangement, or any other arrangement.
When used, multicomponent fibers can also be splittable. In fabricating multicomponent fibers that are splittable, the individual segments that collectively form the unitary multicomponent fiber are contiguous along the longitudinal direction of the multicomponent fiber in a manner such that one or more segments form part of the outer surface of the unitary multicomponent fiber. In other words, one or more segments are exposed along the outer perimeter of the multicomponent fiber. For example, splittable multicomponent fibers and methods for making such fibers are described in U.S. Pat. No. 5,935,883 to Pike and U.S. Pat. No. 6,200,669 to Marmon, et al.
The substrate of the present disclosure can also contain a coform material. The term “coform material” generally refers to composite materials including a mixture or stabilized matrix of thermoplastic fibers and a second non-thermoplastic material. As an example, coform materials can be made by a process in which at least one meltblown die head is arranged near a chute through which other materials are added to the web while it is forming. Such other materials can include, but are not limited to, fibrous organic materials such as woody or non-woody pulp such as cotton, rayon, recycled paper, pulp fluff and also superabsorbent particles, inorganic absorbent materials, treated polymeric staple fibers and the like. Some examples of such coform materials are disclosed in U.S. Pat. No. 4,100,324 to Anderson, et al.; U.S. Pat. No. 5,284,703 to Everhart, et al.; and U.S. Pat. No. 5,350,624 to Georger, et al.
Additionally, the substrate can also be formed from a material that is imparted with texture one or more surfaces. For instance, in some aspects, the substrate can be formed from a dual-textured spunbond or meltblown material, such as described in U.S. Pat. No. 4,659,609 to Lamers, et al. and U.S. Pat. No. 4,833,003 to Win, et al.
In one particular aspect of the present disclosure, the substrate is formed from a hydroentangled nonwoven fabric. Hydroentangling processes and hydroentangled composite webs containing various combinations of different fibers are known in the art. A typical hydroentangling process utilizes high pressure jet streams of water to entangle fibers and/or filaments to form a highly entangled consolidated fibrous structure, e.g., a nonwoven fabric. Hydroentangled nonwoven fabrics of staple length fibers and continuous filaments are disclosed, for example, in U.S. Pat. No. 3,494,821 to Evans and U.S. Pat. No. 4,144,370. Hydroentangled composite nonwoven fabrics of a continuous filament nonwoven web and a pulp layer are disclosed, for example, in U.S. Pat. No. 5,284,703 to Everhart, et al. and U.S. Pat. No. 6,315,864 to Anderson, et al.
Of these nonwoven fabrics, hydroentangled nonwoven webs with staple fibers entangled with thermoplastic fibers is especially suited as the substrate. In one particular example of a hydroentangled nonwoven web, the staple fibers are hydraulically entangled with substantially continuous thermoplastic fibers. The staple can be cellulosic staple fiber, non-cellulosic staple fibers or a mixture thereof. Suitable non-cellulosic staple fibers includes thermoplastic staple fibers, such as polyolefin staple fibers, polyester staple fibers, nylon staple fibers, polyvinyl acetate staple fibers, and the like or mixtures thereof. Suitable cellulosic staple fibers include for example, pulp, thermomechanical pulp, synthetic cellulosic fibers, modified cellulosic fibers, and the like. Cellulosic fibers can be obtained from secondary or recycled sources. Some examples of suitable cellulosic fiber sources include virgin wood fibers, such as thermomechanical, bleached and unbleached softwood and hardwood pulps. Secondary or recycled cellulosic fibers can be obtained from office waste, newsprint, brown paper stock, paperboard scrap, etc., can also be used. Further, vegetable fibers, such as abaca, flax, milkweed, cotton, modified cotton, cotton linters, can also be used as the cellulosic fibers. In addition, synthetic cellulosic fibers such as, for example, rayon and viscose rayon can be used. Modified cellulosic fibers are generally composed of derivatives of cellulose formed by substitution of appropriate radicals (e.g., carboxyl, alkyl, acetate, nitrate, etc.) for hydroxyl groups along the carbon chain.
One particularly suitable hydroentangled nonwoven web is a nonwoven web composite of polypropylene spunbond fibers, which are substantially continuous fibers, having pulp fibers hydraulically entangled with the spunbond fibers. Another particularly suitable hydroentangled nonwoven web is a nonwoven web composite of polypropylene spunbond fibers having a mixture of cellulosic and non-cellulosic staple fibers hydraulically entangled with the spunbond fibers.
The substrate of the present disclosure can be prepared solely from thermoplastic fibers or can contain both thermoplastic fibers and non-thermoplastic fibers. Generally, when the substrate contains both thermoplastic fibers and non-thermoplastic fibers, the thermoplastic fibers make up from about 10% to about 90%, by weight of the substrate. In a particular aspect, the substrate contains between about 10% and about 30%, by weight, thermoplastic fibers.
For this disclosure, a nonwoven substrate will have a basis weight in the range of about 10 gsm (grams per square meter) to about 200 gsm, more typically, between about 15 gsm to about 150 gsm. For particularly suitable substrates, the basis weight will be in the 20 gsm to 50 gsm range.
The thermoplastic materials or fibers making-up at least a portion of the substrate can essentially be any thermoplastic polymer. Suitable thermoplastic polymers include polyolefins, polyesters, polyamides, polyurethanes, polyvinylchloride, polytetrafluoroethylene, polystyrene, polyethylene terephthalate, biodegradable polymers such as polylactic acid and copolymers and blends thereof. Suitable polyolefins include polyethylene, e.g., high density polyethylene, medium density polyethylene, low density polyethylene and linear low density polyethylene; polypropylene, e.g., isotactic polypropylene, syndiotactic polypropylene, blends of isotactic polypropylene and atactic polypropylene, and blends thereof; polybutylene, e.g., poly(l-butene) and poly(2-butene); polypentene, e.g., poly(l-pentene) and poly(2-pentene); poly(3-methyl-1-pentene); poly(4-methyl 1-pentene); and copolymers and blends thereof. Suitable copolymers include random and block copolymers prepared from two or more different unsaturated olefin monomers, such as ethylene/propylene and ethylene/butylene copolymers. Suitable polyamides include nylon 6, nylon 6/6, nylon 4/6, nylon 11, nylon 12, nylon 6/10, nylon 6/12, nylon 12/12, copolymers of caprolactam and alkylene oxide diamine, and the like, as well as blends and copolymers thereof. Suitable polyesters include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polytetramethylene terephthalate, polycyclohexylene-1,4-dimethylene terephthalate, and isophthalate copolymers thereof, as well as blends thereof. These thermoplastic polymers can be used to prepare both substantially continuous fibers and staple fibers, in accordance with the present disclosure.
In another aspect, the substrate can be a tissue product. The tissue product can be of a homogenous or multi-layered construction, and tissue products made therefrom can be of a single-ply or multi-ply construction. The tissue product desirably has a basis weight of about 10 g/m2 to about 65 g/m2, and density of about 0.04 g/cc or more. More desirably, the basis weight will be about 40 g/m2 or less and the density will be about 0.2 g/cc or more. Most desirably, the density will be about 0.3 g/cc or more. Unless otherwise specified, all amounts and weights relative to the paper are on a dry basis. Tensile strengths in the machine direction can be in the range of from about 100 to about 5,000 grams per inch of width. Tensile strengths in the cross-machine direction are from about 50 grams to about 2,500 grams per inch of width. Absorbency is typically from about 5 grams of water per gram of substrate to about 9 grams of water per gram of substrate prior to any treatment being applied.
Conventionally pressed tissue products and methods for making such products are well known in the art. Tissue products are typically made by depositing a papermaking furnish on a foraminous forming wire, often referred to in the art as a Fourdrinier wire. Once the furnish is deposited on the forming wire, it is referred to as a web. The web is dewatered by pressing the web and drying at elevated temperature. The particular techniques and typical equipment for making webs according to the process just described are well known to those skilled in the art. In a typical process, a low consistency pulp furnish is provided from a pressurized headbox, which has an opening for delivering a thin deposit of pulp furnish onto the Fourdrinier wire to form a wet web. The web is then typically dewatered to a fiber consistency of from about 7% to about 25% (total web weight basis) by vacuum dewatering and further dried by pressing operations wherein the web is subjected to pressure developed by opposing mechanical members, for example, cylindrical rolls. The dewatered web is then further pressed and dried by a steam drum apparatus known in the art as a Yankee dryer. Pressure can be developed at the Yankee dryer by mechanical means such as an opposing cylindrical drum pressing against the web. Multiple Yankee dryer drums can be employed, whereby additional pressing is optionally incurred between the drums. The formed sheets are considered to be compacted because the entire web is subjected to substantial mechanical compressional forces while the fibers are moist and are then dried while in a compressed state.
One particular aspect of the present disclosure utilizes an uncreped through-air-drying technique to form the tissue product. Through-air-drying can increase the bulk and softness of the web. Examples of such a technique are disclosed in U.S. Pat. No. 5,048,589 to Cook, et al.; U.S. Pat. No. 5,399,412 to Sudall, et al.; U.S. Pat. No. 5,510,001 to Hermans, et al.; U.S. Pat. No. 5,591,309 to Ruqowski, et al.; U.S. Pat. No. 6,017,417 to Wendt, et al., and U.S. Pat. No. 6,432,270 to Liu, et al. Uncreped through-air-drying generally involves the steps of: (1) forming a furnish of cellulosic fibers, water, and optionally, other additives; (2) depositing the furnish on a traveling foraminous belt, thereby forming a fibrous web on top of the traveling foraminous belt; (3) subjecting the fibrous web to through-air-drying to remove the water from the fibrous web; and (4) removing the dried fibrous web from the traveling foraminous belt.

Polyolefin Dispersion

HYPOD 8510 polyolefin dispersion is a DOW Chemical product that can be used to provide softness for the facial tissue. HYPOD polyolefin dispersion is a polyolefin dispersion; polyolefin dispersions typically have very low surface energy and do not wet out well, are inert chemically, and are water based. Some advantages of the polyolefin dispersion are 1) water resistance, 2) oil and grease resistance, 3) heat seal ability, 4) low temperature flexibility, and 5) it can be applied using low viscosity methods such as spraying, printing, and foaming. The ethylene octene copolymer contributes softness and the ethylene acrylic acid is the binder that keeps the particles from agglomerating in the dispersion. The use of HYPOD polyolefin dispersion is further described in U.S. Patent Publication No. US20120164200 and in U.S. patent application Ser. No. 13/905,429, each of which is incorporated herein by reference to the extent it does not conflict herewith.

Hydrophobic Coating

The hydrophobic component is a hydrophobic polymer that is dispersible in water to form the basic elements of the hydrophobic properties of the present disclosure. In general, a hydrophobic component of this disclosure can include, but is not limited to, fluorinated or perfluorinated polymers. However, due to low degree of water dispersibility, the fluorinated or perfluorinated polymer can need to be modified by introducing a comonomer onto their molecular structure. Suitable comonomers include, but are not limited to, ethylenically unsaturated monomers including functional groups that are capable of being ionized in water. One example is ethylenically unsaturated carboxylic acid, such as acrylic acid. The amount of the comonomer within the hydrophobic component is determined by balancing two properties: hydrophobicity and water dispersibility. One example of the hydrophobic component of this disclosure is a commercially available modified perfluorinated polymer compound available from DUPONT as a water-based product under the trade name CAPSTONE STC-100. Due to its low surface energy, the polymer contributes to the hydrophobicity. Additionally, the polymer molecules can be modified to contain groups, such as amines, that can become charged upon pH reduction and alter the dynamics of hydrophobicity within the liquid dispersion. In such a case, the polymer can stabilize in water through partial interaction. Surfactants that are introduced into the composition can also behave as dispersants of the polymer, thereby also altering some of the hydrophobic mechanics. Hydrophobic coatings are further described in U.S. patent application Ser. No. 13/193,065, which is incorporated herein by reference to the extent it does not conflict herewith.
The solid components of the present disclosure can be present in an amount from about 1.0% to about 3.0%, by weight of the solution. Such an amount is suitable for spray applications where higher concentrations of polymer can lead to either viscoelastic behavior, resulting in either clogging of the spray nozzle or incomplete atomization and fiber formation, or dramatic increases in dispersion viscosity and thus nozzle clogging. It should be noted that this range is not fixed and that it is a function of the materials being utilized and the procedure used to prepare the dispersion. When a higher amount of the polymer is used, the surface structure is less desirable as it lacks the proper texture to be hydrophobic. When a lower amount of the polymer is used, the binding is less desirable as the coating behaves more so as a removable powder coating.
UNIDYNE KCO3 fluorinated water and oil repellent is composed of water, flouroalkyl methacrylate copolymer, emulsifiers, and tripropylene glycol. It is a cost effective, soil resistant, oil and water repellant flouropolymer. The function of water and oil repellency is due to UNIDYNE KCO3 fluorinated water and oil repellent reducing the surface energy. This reduction of surface energy is due to the fluorine that is present. Daikin UNIDYNE products have been investigated in the past and is currently used in, for example, surgical gowns.
DUPONT CAPSTONE STC-100 is an aqueous flourochemical dispersion that provides a transparent protective barrier against oil and water on porous surfaces.
FENNOSIZE BMP sizing is available from Kemira Chemicals, Helsinki, Finland. It is a water-dispersible surface sizing. POLYGRAPHIX sizing is also available from Kemira Chemicals.
PRECIS 2090 sizing is an internal alkyl ketene dimer (AKD) sizing agent from Hercules Corporation. Internal sizing is also based on lowering the surface energy of the cellulose. The bulk sizing technique includes an AKD molecule binding to the cellulose fiber.

Non-Organic Solvent

The formulation used in treating the surface of the present disclosure eliminates the use of an organic solvent by carefully selecting the appropriate combination of elements to impart the hydrophobic characteristics. Preferably, the non-organic solvent is water. Any type of water can be used; however, demineralized or distilled water can be opted for use during the manufacturing process for enhanced capabilities. The use of water helps to reduce the safety concerns associated with making commercial scale formulations including organic solvents. For example, due to the high volatility and flammability of most organic solvents, eliminating such use in the composition reduces production safety hazards. Additionally, production costs can be lowered with the elimination of ventilation and fire prevention equipment necessitated by organic solvents. Raw material costs can be reduced in addition to the transportation of such materials as an added advantage to utilizing the non-organic solvent formulation to arrive at the present disclosure.
The formulation used to treat the surface of the present disclosure includes greater than about 95%, greater than about 98%, or about 99% water, by weight of the dispersion composition.

Other Optional Ingredients

Binders

The hydrophobic polymers within the formulation of the present disclosure can play a dual role in acting both as a hydrophobic component and a binder. Polymers such as DUPONT CAPSTONE STC-100 promote adhesion, as compared to the fluorinated polymer alone, so that an additional binder within the composition is not necessary. If a water-dispersible hydrophobic polymer is used wherein an additional binder is needed, it is preferred that the binder is selected from water-dispersible acrylics, polyurethane dispersions, acrylic copolymers, or acrylic polymer precursors (which can cross link after the coating is cured).
The amount of the binder present within the formulation of the present disclosure can vary. A binder can be included in an effective amount of up to about 2.0% by weight of the total dispersion composition.

Stabilizing Agent

The formulation within the present disclosure can be additionally treated with a stabilizing agent to promote the formation of a stable dispersion when other ingredients are added to it. The stabilizing agent can be a surfactant, a polymer, or mixtures thereof. If a polymer acts as a stabilizing agent, it is preferred that the polymer differ from the hydrophobic component used within the base composition previously described.
Additional stabilizing agents can include, but are not limited to, cationic surfactants such as quaternary amines; anionic surfactants such as sulfonates, carboxylates, and phosphates; or nonionic surfactants such as block copolymers containing ethylene oxide and silicone surfactants. The surfactants can be either external or internal. External surfactants do not become chemically reacted into the base polymer during dispersion preparation. Examples of external surfactants useful herein include, but are not limited to, salts of dodecyl benzene sulfonic acid and lauryl sulfonic acid salt. Internal surfactants are surfactants that do become chemically reacted into the base polymer during dispersion preparation. An example of an internal surfactant useful herein includes 2, 2-dimethylol propionic acid and its salts.
In some aspects, the stabilizing agent used within the composition to treat the surface of the present disclosure can be used in an amount ranging from greater than zero to about 80% of the hydrophobic component. For example, long chain fatty acids or salts thereof can be used from about 0.5% to about 10% by weight based on the amount of hydrophobic component. In other aspects, ethylene-acrylic acid or ethylene-methacrylic acid copolymers can be used in an amount up to about 80%, by weight based of hydrophobic component. In yet other aspects, sulfonic acid salts can be used in an amount from about 0.01% to about 60% by weight based on the weight of the hydrophobic component. Other mild acids, such as those in the carboxylic acid family (e.g., formic acid), can also be included in order to further stabilize the dispersion. In an aspect that includes formic acid, the formic acid can be present in an amount that is determined by the desired pH of the dispersion wherein the pH is less than about 6.

Additional Fillers

The composition used to treat the surface of the present disclosure can further include one or more fillers. The composition can include from about 0.01 to about 600 parts, by weight of the hydrophobic component, for example, polyolefin and the stabilizing agent. In certain aspects, the filler loading in the composition can be from about 0.01 to about 200 parts by the weight of the hydrophobic component, for example, polyolefin, and the stabilizing agent. It is preferred that such filler material, if used, be hydrophilic. The filler material can include conventional fillers such as milled glass, calcium carbonate, aluminum trihydrate, talc, antimony trioxide, fly ash, clays (such as bentonite or kaolin clays for example), or other known fillers. Untreated clays and talc are usually hydrophilic by nature.

Examples

The following are provided for exemplary purposes to facilitate understanding of the disclosure and should not be construed to limit the disclosure to the examples.
Sample Fabrication. The following matrix of samples was created:


	Chemistries

		Formula-	Formula-	FENNOSIZE	POLYGRAPHIX	PRECIS
Substrates	UNIDYNE	tion III	tion V	sizing	sizing	sizing

Substrate B	X	X	X	X	X
Substrate B + HYPOD dispersion	X	X	X	X	X
Substrate A	X	X	X	X	X
Substrate A + HYPOD dispersion	X	X	X	X	X
Handsheets						X
Handsheets/PRECIS sizing	X		X

For the substrates that were coated with UNIDYNE KCO3 fluorinated water and oil repellent, Formulation III, Formulation V, FENNOSIZE sizing, PRECIS sizing, and POLYGRAPHIX sizing were added onto at a low, medium, and high level. Low was approximately 1 gsm, medium was approximately 5 gsm, and high was approximately 10 gsm. These chemistries were added on using an atomizing sprayer and an Allen Bradley Panelview Controller 550.
Recipes for each chemistry are as follows:


		Cycle
		speed		Approx-
		setting		imate
Substrate	Formula	(fpm)	Passes	gsm

Nanoclay on Substrate A + HYPOD dispersion

Substrate A +	Formulation V -	56	4	1
HYPOD dispersion	6.5% PMC + 1.25%
	nanoclay + water
Substrate A +	Formulation V -	46	5	5
HYPOD dispersion	12.5% PMC + 2.5%
	nanoclay + water

UNIDYNE KC03 on Substrate A + HYPOD dispersion

Substrate A +	KC03 - 30%	77	4	1
HYPOD dispersion
Substrate A +	KC03 - 100%	46	2	5
HYPOD dispersion
Substrate A +	KC03 - 100%	46	4	10
HYPOD dispersion

Formulation III on Substrate A + HYPOD dispersion

Substrate A +	Formulation III -	56	2	1
HYPOD dispersion	31.25% PMC + water
Substrate A +	Formulation III -	56	5	5
HYPOD dispersion	31.25% PMC + water
Substrate A +	Formulation III -	56	2	10
HYPOD dispersion	62.5% PMC + water

FENNOSIZE sizing on Substrate A + HYPOD dispersion

Substrate A +	FENNOSIZE	56	3	10
HYPOD dispersion	sizing 80%

Formulation III on Substrate B

Substrate B 5%	Formulation III -	56	3	1
	31.25% PMC + water
Substrate B 5%	Formulation III -	56	4	5
	31.25% PMC + water
Substrate B 5%	Formulation III -	56	5	10
	62.5% PMC + water

Nanoclay on Substrate B

Substrate B 5%	Formulation V -	46	2	1
	6.25% PMC + 1.25%
	nanoclay + water
Substrate B 5%	Formulation V -	46	5	5
	12.5% PMC + 2.5%
	nanoclay + water
Substrate B 5%	Formulation V - 25%	46	5	10
	PMC + 5%
	nanoclay + water

UNIDYNE KC03 on Substrate B

Substrate B 5%	30% UNIDYNE KC03	90	1	1
Substrate B 5%	UNIDYNE KC03	46	1	5
Substrate B 5%	UNIDYNE KC03	46	2	10

Formulation III on Substrate B + HYPOD dispersion

Substrate B +	Formulation III -	56	4	1
HYPOD dispersion	6.25% PMC
Substrate B +	Formulation III -	56	3	5
HYPOD dispersion	62.5% PMC + water
Substrate B +	Formulation III -	56	5	10
HYPOD dispersion	62.5% PMC + water

UNIDYNE KC03 on Substrate B + HYPOD dispersion

Substrate B +	UNIDYNE KC03 -	77	1	1
HYPOD dispersion	30%
Substrate B +	UNIDYNE KC03	46	1	4
HYPOD dispersion
Substrate B +	UNIDYNE KC03	46	2	10
HYPOD dispersion

Nanoclay on Substrate A

Substrate A Plain	Formulation V - 6.5%	56	2	1
	PMC + 1.25%
	nanoclay + water
Substrate A Plain	Formulation V - 25%	46	3	5
	PMC + 5%
	nanoclay + water
Substrate A Plain	Formulation V - 25%	46	5	10
	PMC + 5%
	nanoclay + water

UNIDYNE KC03 on Substrate A

Substrate A Plain	UNIDYNE KC03 30%	56	3	5
Substrate A Plain	UNIDYNE KC03 30%	56	3	10

Formulation III on Substrate A

Substrate A Plain	Formulation III -	56	1	1
	31.25% PMC + water
Substrate A Plain	Formulation III -	56	4	5
	31.25% PMC + water
Substrate A Plain	Formulation III -	56	5	9
	62.5% PMC + water

Substrate A and Substrate B samples were coated twice on each side using the following creping technique: the chemicals were foamed and then applied to the dryer surface. This creping technique improves application efficiency by reducing waste because the chemistry applicator can be placed in much closer proximity to the dryer surface than liquid spray tips (¼″ vs. 4″). Liquid and air was pumped into a mixer that blends the air into the fluid and produces foam that contains fine bubbles. This foam exits the mixer and flows to an applicator that is placed closely to the dryer surface to uniformly distribute the foam.
Handsheet samples were made with 70% Pictou Pulp and 30% Eucalyptus Pulp. The PRECIS sizing addition was added into the pulp water mixture per the required concentration. The following PRECIS sizing handsheets were created: Control: no PRECIS sizing, 2 lbs PRECIS sizing/MT pulp, 4 lbs PRECIS sizing/MT pulp, 8 lbs PRECIS sizing/MT pulp, 16 lbs PRECIS sizing/MT pulp, 32 lbs PRECIS sizing/MT pulp. A set of handsheets with each level of PRECIS sizing add-on was then spray coated with UNIDYNE KCO3 fluorinated water and oil repellent chemistry and another set with Formulation V.

Drop Test

The drop test was the initial screening method for these samples. A drop of water was placed on the sample and a stop watch was started. When the sample penetrated or was absorbed, the stop watch was stopped and the time was noted. If the drop penetrated in under 60 seconds, those samples were discarded. If a drop stayed at least 60 seconds, then those samples were tested with Functional Water Barrier Testing and Hydrohead. Samples that had to be eliminated via this technique were all substrates that had been treated with POLYGRAPH IX sizing chemistry and substrates with low add-ons of the FENNOSIZE sizing chemistry. Substrates that were coated with only HYPOD polyolefin dispersion also did not pass this test.

Hydrohead

Hydrohead was measured with hydrohead equipment that was created in the University of Illinois in Chicago. Water is pumped into a column graded for centimeters of water. The sample is attached to the bottom of the column, treated side toward the water. A mirror is placed on the underside of the sample. When the first drop is visualized, the valve is closed and the height of the water is recorded. FIG. 9 shows an image of the apparatus.
Data shows that hydrohead trend can increase slightly with add-on level but is mainly dictated by substrate. HYPOD polyolefin dispersion coated Substrate A and Substrate B generally have higher hydrohead than non-HYPOD polyolefin dispersion coated samples. FIG. 1 shows hydrohead trends for these substrates. Handsheets increase in hydrohead as size concentration is increased and then decreases. FIG. 2 shows the effect of bulk sizing on the handsheets.

Functional Water Barrier Testing

The purpose of the Functional Water Barrier Test is to help determine the ability of treated substrates to withstand insults of water meant to replicate a baby's urine. The test is done by placing a piece of blotter paper beneath the treated substrate. A diaper core is placed atop the substrate and insulted with saline. A weight is then placed on the diaper core and left to rest for 15 minutes. The blotter paper is then weighed and compared to its starting weight to determine the substrates effectiveness.

Steps to Follow

- 1) Weigh blotter papers and diapers cores. Record measurements in spreadsheet. Keep as matched pairs for proper calculations.
- 2) Fill syringes with total of 127 ml per sample, three samples per code.
- 3) Layer blotter paper, treated substrate within plastic shield and diaper cores.
- 4) Insult sample with 127 ml of saline and start timer for 15 minutes.
- 5) Wait one minute and place weight on top of stack.
- 6) Repeat process for next two samples.
- 7) Weigh blotter papers at end of 15 minutes.

It was found that there were three regimes of water barrier with this kind of testing: “No barrier”—where the saline permeated the outer cover sample; “Barrier: Feels Clammy”—where the amount of saline that permeated the outer cover was so low it was more of a water vapor transmission; and “Barrier: feels dry”—where the amount of saline that permeated the outer cover was either none or was so low that it was not detectable by touch, only by gravimetric analysis. FIGS. 3 and 4 show the Substrate A and Substrate B based samples that fell into the regimes. FIG. 5 shows the functional water barrier test behavior for handsheets. Handsheet barrier falls from no barrier to “feels clammy” with the smallest sizing amount and then slightly increases but stays in that “feels clammy” regime. Handsheets with hydrophobic chemistries in addition to the sizing fall into the same “feels clammy” regime, even with zero sizing. The hydrophobic add-ons were approximately 0.1 gsm for Nanoclay and 2 gsm for UNIDYNE KCO3 fluorinated water and oil repellent.

Air Permeability

The samples were tested for air permeability. The air permeability testing was Standard Test Method (STM) EQ-STM-3801: “Air Permeability—Tesxtest FX 3300.” It was found that like hydrohead, air permeability depended mainly on the type of substrate. FIG. 6 shows air permeability for different samples. Substrate B basesheets with hydrophobic chemistries had the most permeability, then Substrate A samples, and then any samples that were coated with polyolefin dispersion and hydrophobic chemistries. Handsheets had the least amount of air permeability. The air permeability of a standard ASFL outer cover is zero.

Analysis

The typical test method to understand the water barrier behavior for diapers is hydrohead. For an outer cover material that provides an adequate water barrier but not necessary a premium water barrier, the hydrohead to be achieved can potentially be much less than the hydrohead of standard premium ASFL outer covers, which was found to be approximately 137 cm of water. Hydrohead is essentially a very robust test that couples strength and impermeability. For an outer cover sample that has been designed for water barrier and not strength, hydrohead measurement can be somewhat of an excessive evaluation that does not necessarily describe the impermeability function. As a result, the functional water barrier test was designed. When hydrohead is plotted against functional water barrier test leakage it can be seen that hydrohead does not necessarily describe all cases of water barrier functionality. For the materials described herein, high hydrohead was always equal to low leakage; high leakage was always equal to low hydrohead; but low hydrohead was not equal to high leakage. Low hydrohead could have high or low leakage. FIG. 7 illustrates this relationship. Note that the functional water barrier test that these hydrohead values were plotted against were carried out in a slightly different way than those in FIGS. 3, 4, and 5. The pressure was increased to 0.2 psi, the core was insulted with saline to 90% of its capacity, and a one-minute wait was provided for the absorbent core to begin to absorb the saline before adding the weight.
Air permeability demonstrated a similar behavior that can be seen in FIG. 8. High and medium air permeability always had low hydrohead; however, samples that had low air permeability varied in hydrohead. This is suspected to be due to the presence of larger pore openings. Samples that had low permeability were those coated with a polyolefin dispersion or were the very dense handsheets. Substrate B had more air permeability than Substrate A.
The presence of pores not only dictated the air permeability, but also seemed to affect the leakage barrier in the FWBT results shown in FIGS. 3 and 4. It can be seen in both figures that tissue coated with a polyolefin dispersion and a hydrophobic chemistry shows a better leakage barrier than the tissues that only have the hydrophobic chemistry. Because of this behavior it is suspected that the water barrier can be achieved by a combination of two mechanisms: surface energy reduction (from the hydrophobic chemistries) and pore clogging (by the polyolefin dispersion coating). Each one of those was not sufficient on its own to create a barrier that felt completely dry.
As described herein, it is possible to create a tissue based water barrier that can be used as an outer cover. A combination of a polyolefin dispersion and hydrophobic/superhydrophobic chemistries can be used to achieve this result. The combination was seen to provide a more uniform treatment of the surface. Such uniformity is important when the function of interest is a barrier because a single weak point can cause the failure of an entire substrate. Prior efforts have focused on treating a basesheet with either a polyolefin dispersion or a hydrophobic/superhydrophobic chemistry. The combination found herein yields unexpected benefit.
The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”
All documents cited in the Detailed Description are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present disclosure. To the extent that any meaning or definition of a term in this written document conflicts with any meaning or definition of the term in a document incorporated by reference, the meaning or definition assigned to the term in this written document shall govern.
While particular aspects of the present disclosure have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the disclosure. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this disclosure.

Claims

What is claimed is:

1. A hydrophobic, liquid-impermeable substrate comprising:

a hydrophilic nonwoven having a treated surface; a polyolefin dispersion disposed on the treated surface; and a hydrophobic chemistry disposed on the polyolefin dispersion.

2. The substrate of claim 1, wherein the hydrophilic nonwoven includes tissue or paper toweling.

3. The substrate of claim 1, wherein the hydrophilic nonwoven includes cellulose.

4. The substrate of claim 1, wherein the hydrophilic nonwoven includes fibers.

5. The substrate of claim 1, wherein the substrate is breathable and exhibits an air permeability of 100 cfm.

6. The substrate of claim 1, wherein the hydrophilic nonwoven includes a hydrophilic surface opposite the treated surface.

7. The substrate of claim 1, wherein the hydrophobic chemistry is a water-dispersible hydrophobic polymer.

8. The substrate of claim 1, wherein the water-dispersible hydrophobic polymer includes a comonomer selected from acrylic monomers, acrylic precursors, and the like.

9. The substrate of claim 1, wherein the hydrophobic chemistry is a superhydrophobic chemistry.

10. The substrate of claim 9, wherein the superhydrophobic chemistry includes a hydrophobic component selected from the group consisting of fluorinated polymers, perfluorinated polymers, and mixtures thereof.

11. The substrate of claim 9, wherein the superhydrophobic chemistry includes one of UNIDYNE KCO3 fluorinated water and oil repellent or the Formulation III chemistry.

12. The substrate of claim 1, wherein the polyolefin dispersion is HYPOD 8510.

13. The substrate of claim 1, further comprising nanoclay.

14. The substrate of claim 1, the further comprising a surfactant, wherein the surfactant is selected from nonionic, cationic, and anionic surfactants.

15. The substrate of claim 1, further comprising a stabilizing agent selected from the group consisting of long chain fatty acids, long chain fatty acid salts, ethylene-acrylic acid, ethylene-methacrylic acid copolymers, sulfonic acid, acetic acid, and the like.

16. The substrate of claim 1, further comprising a filler selected from the group consisting of milled glass, calcium carbonate, aluminum trihydrate, talc, antimony trioxide, fly ash, clays, and the like.

17. A method for preparing a hydrophobic, breathable, liquid-impermeable substrate comprising:

providing a hydrophilic nonwoven having a treated surface;

applying a polyolefin dispersion to the treated surface; and

applying a hydrophobic chemistry to the polyolefin dispersion.

18. The method of claim 17, wherein the hydrophilic nonwoven includes tissue or paper toweling.

19. The method of claim 17, wherein the hydrophobic chemistry is a water-dispersible hydrophobic polymer.

20. The method of claim 17, wherein the hydrophobic chemistry is a superhydrophobic chemistry.