CA1192364A - Process for the production of alginate fibre material and products made therefrom - Google Patents
Process for the production of alginate fibre material and products made therefromInfo
- Publication number
- CA1192364A CA1192364A CA000409567A CA409567A CA1192364A CA 1192364 A CA1192364 A CA 1192364A CA 000409567 A CA000409567 A CA 000409567A CA 409567 A CA409567 A CA 409567A CA 1192364 A CA1192364 A CA 1192364A
- Authority
- CA
- Canada
- Prior art keywords
- fibres
- web
- sheet
- alginate
- dried
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
- D01F9/04—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of alginates
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
- A61L15/00—Chemical aspects of, or use of materials for, bandages, dressings or absorbent pads
- A61L15/16—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons
- A61L15/22—Bandages, dressings or absorbent pads for physiological fluids such as urine or blood, e.g. sanitary towels, tampons containing macromolecular materials
- A61L15/28—Polysaccharides or their derivatives
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T428/2913—Rod, strand, filament or fiber
- Y10T428/2922—Nonlinear [e.g., crimped, coiled, etc.]
- Y10T428/2924—Composite
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T428/2913—Rod, strand, filament or fiber
- Y10T428/2922—Nonlinear [e.g., crimped, coiled, etc.]
- Y10T428/2925—Helical or coiled
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
- Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
- Y10T442/643—Including parallel strand or fiber material within the nonwoven fabric
- Y10T442/645—Parallel strand or fiber material is inorganic [e.g., rock wool, mineral wool, etc.]
Abstract
ABSTRACT OF THE DISCLOSURE
A process for the production of dried alginate fibre material which includes the operations of spinning an aqueous solution of a soluble alginate salt into a spin bath containing an aqueous solution of a salt, for example a calcium salt, to provide wet spun fibres of insoluble alginate, forming a sheet of the wet spun insoluble undried alginate fibres in which the individual fibres are separated and disposed in generally parallel relation-ship, feeding forwards and laying the sheet of undried fibres onto a moving conveyor device which is travelling at a slower speed than said sheet in the feed direction whereby the fibres become overlaid in crossing-over intersecting relationship to form a web, followed by further processing in which said sheet or web of intersecting overlaid fibres is subjected to a dewatering drying operation, the improvement consisting in incorporating into the process at least one controlled treatment step which is effective to eliminate or reduce bonding of the overlaid fibres at their points of contact or intersection and to ensure thereby that the dried non-woven web constituting the dried alginate fibre material which is the end product of said process has minimal degree of bonding between the fibres.
A process for the production of dried alginate fibre material which includes the operations of spinning an aqueous solution of a soluble alginate salt into a spin bath containing an aqueous solution of a salt, for example a calcium salt, to provide wet spun fibres of insoluble alginate, forming a sheet of the wet spun insoluble undried alginate fibres in which the individual fibres are separated and disposed in generally parallel relation-ship, feeding forwards and laying the sheet of undried fibres onto a moving conveyor device which is travelling at a slower speed than said sheet in the feed direction whereby the fibres become overlaid in crossing-over intersecting relationship to form a web, followed by further processing in which said sheet or web of intersecting overlaid fibres is subjected to a dewatering drying operation, the improvement consisting in incorporating into the process at least one controlled treatment step which is effective to eliminate or reduce bonding of the overlaid fibres at their points of contact or intersection and to ensure thereby that the dried non-woven web constituting the dried alginate fibre material which is the end product of said process has minimal degree of bonding between the fibres.
Description
~2~
The present lnvention relates to a process for the production of alginate fibres~ particularly dried alginate ~lbre materlal, and to products made therefrom~ it is especially, although not exclus~vely, useful for the commercial manufacture and preparatlon of materlals and products, composed of alginate ~ibres, for use as swabs or dresslngs and the like suitable for medical, surgical and other purposes.
10The extrusion of alginate solutions into coagulating baths or spin baths containing for example aqueous solutlons providing calcium ions to form or spin yarns of insoluble alginate salt filaments ls a well known process.
15It is also well known to prepare and use materials or fabrics composed of alginate flbres, especially calcium and sodium/calclum mlxed salt alginate ~ibres, for surgical and medical purposes, for instance in the form Or dressings and the like in connection with which the haemostatic properties of the alginate and, in some casesJ solubillty ln body fluids can be partlcularly valuable. Such uses are for example described in British Patents Nos. 653341 and 1394741.
25In the past, alginate fabrics for providing surgical and medical dressing~ and the like have generally been produced ~rom continuous calciu~ alginate filament yarn by 36~
knltting~ When the alginake material is required in the more soluble sodlum/calcium mixed salt ~orrn, which is commonly preferred and is mor-e useful ln many cases, the knitted fabric ls then treated or "converted" to replace part o~ the calcium content by the more solubili3ing sodlum cation.
This converslon o~ the calcium alginate to the more soluble sodium/calcium alginate mixed salt form ls the subJect of a number o~ Patent publications and an excellent summary is glven in Britiqh Patent No. 1394741 which sets out the basis for a process whlch ls technically superior to previous methodsO In practice, however, the treatment or conversion process performed on the knitted fabric has usually involved handling problems and has been carried out batchwise whlch is rather ine~ficient and uneconomic resulting in a costly and wasteful production process.
As wlll be seen later~ the process of the preeent invention can enable calcium alginate fibres to be wet spun and processed to ~orm a dried alginate fibre material in a continuous series of operations which can include, when required5 a step of convertlng the calcium alginate fibr-e materlal into the sodium/calcium mixed salt form. The dried alginate fibre material so fvrmed may then be made up into a tow suitable for swab production or alginate wool or into the ~orm o~ a non-woven wadding suitable for use as a 3~
medical or surgical dressing. The entire process can be performed without handling the material, using simple machinery which ls easy to maintain to the standards of cleanliness required of this type of product.
A factor to be considered 9 however, in the production and processing of alginate fibres is the tendency of such fibres~ when wet, to adhere and fuse together on drylng.
This tendency is of ma~or importance in the drying of wet newly-spun "never-drled" alginate ~ibres since these are extremely soft and have a very high water content so thatJ
during drying, considerable dewatering takes place and ad~acent individual fibres or filaments are caused to adhere to each other by capillary action and become bonded together. This bonding effect can be dramatically increased by any mechanical forces externally applied at the dewatering drying stageO
It may be noted that this tendency for inter-~ibre bonding to occur is not so important in drying "re-wetted"
alginate flbres~ that is, alginate fibres or yarns which have been dried after being lnitially spun and which have then subsequently been re-wetted~ In the latter case 3 provided a significant degree of fibre bonding has been avoided ln first producing and drying the fibres it is found that on subsequent re-wetting considerably less water is taken up by the fibres and during re-drying the tendency ~Z3~;~
for the fibres to adhere and bond together is very much reduced. On the other hand, in any continuous productlon process which starts with the inltial step of wet spinnlng calcium alglnate fibre filaments one ls necessarily deallng wlth "never-dried" alglnate flbres whlch remaln wet up to the drying stage at whlch the tendency to adhere and bond together arlses as discussed above.
In the commercial productlon of contlnuous drled alginate filament yarns the problem of excessive and undesirable bonding between individual ~ibre ~ilaments may be overcome by coating the fllaments before drylng with a substance such as an emulsified oil which prevents the filaments from sticking together. Or, as an alternative remedyS flbre adhesion may be inhibited by exchanglng and removing the waker with an organ-lc water soluble solvent such as acetone or a lower alcohol at a su~ficiently hlgh concentration.
It has been already-dried alglnate ~ilament yarns as referred to above which have previously been commonly used for making knitted alginate fabrics in the conventional processes for providing surgical and medical alginate dressings. It has, howeverg also been proposed in 25 publication document WO 80/02300 of International Patent Application No. PCT/GE80/00066 (Courkaulds Limited) to provide a non~woven alginate fabric for use as an alginate 3`~
dressing and a process for the production of such non-woven fabric is disclosed therein.
According to the process of W0 80/02300, a tow of stretched and washed spun calcium alginate ~ibres or filaments is passed in a flow of water through a spreading device, such as a device with a "fish tail" outlet, and the spread band or sheet produced is fed forwards and deposited on a liquid permeable conveyor, such as a Fourdrinier wire mesh conveyor, moving at a slower speed so that the fibres are overlaid in a substantially uniform layer or sheet forming a web whlch iæ then dried to provide a unitary non-woven alginate fabric. As a result of the overlaying, the fibres become crimped or looped and cross over each other in the web so that a parallel orientation thereof is destroyed; it will be appreciated that this reduces the contact area~of the fibres and prevents the ~ormation, in the subsequent dewatering drying operation, of a sheet in which parailel fibres are bonded and fused together along their length. Such a sheet of parallel bonded alginate fibres would be completely unsuitable for medical or surgical alginate dressings.
The advantages resulting from overlaying the fibres as described above suggests that no other special measures need to be taken to counteract bonding together of the fibres. Indeed, on the contrary, the disclosure in W0 3~
80/02300 indicates that some fibre bonding is desirable and particularly emphasises that although lengthwlse bonding is avolded the overlaid ~ibres in the web produced should still be bonded at their points of contact where they cross over each other; the drying operatlon in the process described accordingly is carried out in a way which applies mechanical forces and promotes such bonding at intersections, first by applying suction directly to the wet overlald fibres on the conveyor and then by passing the partially dried web around heated cylinders. Also, a way of further lncreasing the degree of such inter-bonding by a treatment of the filaments on the conveyor with an aqueous solution of a sodium salt, preferably a sodium salt o~ an acid which forms on insoluble calcium salt, before completlng the drying operation is described. A non-woven alginate fabric is thus produced by the process of W0 80/02300 consisting essentially of a dried web of intersecting alginate fibres or filaments bonded together at their cross-over points to provide a strong unitary structure~
The production of non woven unitary webs or fabrics directly from tows of continuous synthetic textile filaments is also already known from U.S. Patent No.
3802980 ~Harmon) which describes a manufacturing process similar in some ways to that described in W0 80/02300, especially in respect of the use of a fish-tail type ~92~6~
spreader to overfeed onto a more slowly moving liquid permeable conveyor a thin sheet or band of filaments or fibres so that the latter become crimped and overlald in crossin~-over or intersecting overlapplng relationship in a continuous fllament sheet which i8 then dried to produce the non-woven unitary web required. The flbres or filaments of the web produced are not described as being bonded and it is implied that frictional engagement between overlapping crimped or looped fibre portions of ad~acent individual filaments suffices to maintain a unitary structure. This may be so~ although it is notable that in the specific examples descrlbed the fllament sheet on the conveyor is sprayed before final drying with a polyvinyl alcohol solution which is known to act as an adhesive and promote bonding to some extent with many fibres.
In any event, the process of U.S. Patent No. 3802980 is not specifically described ~s being applied to alginate ~lbres or filaments but appears to be directed more to synthetlc textile ~ilaments such as viscose rayon, nylon~
polyesters, acrylics and polyoleflns etc., and it can be inferred that the lnitial tows to which lt is expected that the process would be applied would be composed of already dried continuous filaments of these materials. If~ on the other hand, the process were to be applied to "never dried'i alginate ~ibres and carried out exactly as described uslng in particular a suction box to remove water from the - - -freshly laid sheet or web on the conveyor, a high deyree of bonding between the fibres or filaments at their cross-over points would inevitably be obtained as in the process of WO
80/02300. This, however, would be quite in accordance with the teaching of the latter and may therefore well be considered to represent a useful advantage.
The process of the present invention has some features in common with that described in WO 80/02300 but it differs in certain very significant respects and there is a fundamental difference in that it departs completely from the teaching of the latter in regard to endeavouring to produce as an end product a unitary non-woven web or fabric composed of a drieA sheet o~ overlaid alginate fibres or filaments which are bonded together where they intersect and cross over each other. On the contrary, the present invention seeks to provide a process, which can be continuously operable, adapted to produce a unitary dried non-woven web of non-bonded algina-te fibres.
Thus, according to the present invention, there is provided a process for the production of dried alginate fib~e material 0 whi~h includes the operations of spinning an aqueous solution of a soluble alginate salt into a spin bath containing an aqueous solution of a salt which provides wet spun fibres of insoluble alginates, forming a sheet of the wet spun insoluble undried alginate fibres in which the individual fibres are separated and disposed in generally parallel relationship, feeding forwards and laying the sheet of undried fibres onto a moving conveyor device which is travelling at a slower speed than said sheet in the feed direction whereby the fibres become overlaid in crosslng-over intersecting relationship to form a sheet-like webl and subjecting said sheet-like web of intersecting overlaid fibres to a dewatering drying operation, _ g _ ~9~3~
wherein the process also includes measures ef~ective to inhibit the occurrence of bonding together of the overlaid crossing-over fibres at their points of contact in the sheet-like web during the dewatering drying operation and wherein, subsequent to the dewatering drying operation, the sheet-like web of overlaid fibres while still in said sheet form is subjected to a "stretch-breaking" operation effective to cause said ibres in the web to be randomly broken.
It will be appreciated that in the present specification the term "web" is used in a broad sense to include any sheet-like layer or matrix of individual fibres and it does not imply that there is necessarily some significant degree of actual bonding or strong permanent adhes.ion between the individual fibres thereof.
It has been found that, despite the teaching of WO
8Q/02300, dried non-wover alginate fibre webs made in accordance with the present invention so as to have but a a~. ~
36~
minimal degree of bondlng between the fibres afford a material which, for the purpose of providing products such as surgical or medical dressings and swabs and the like, is in general much superlor to that a~forded by dried non-woven alginate fibre webs havlng a high degree of flbre-fibre bonding.
This superiority arises primarily from the fact that the webs made in accordance with the invention with minimal inter fibre bonding present a significantly softer texture and of~er greater scope for various dif~erent finishing operations in preparing or making up final materials or products having desired characteristics for surgical or medical use. As will hereinafter be apparent, a range of options is available for further processlng these webs of dried alginate fibre material for the purposes required, including making up lnto comparatively thick multilayer ~abrlcs by cross-laying and introducing a carefully controlled amount of bonding between layers to provide soft non-woven wadding, and forming or gathering into a tow of separate and substantially parallel fibres which can then be staple cut and used to make wadding by air laying or to make alginate wool with a further option o~ introducing and blending with other different fibres.
Advantageously in some cases, as hereinafter described in accordance with a further aspect of the ~9~3~
invention, the fibres of such webs may also be randomly broken by a stretch breaking operation before being made up for example into a cross-laid multilayer fabric for waddlng, this stretch breaking yielding material of non-bonded fibres which may be similar to that produced by akextile card.
In contrast with the material obtained by means of the present invention, non-woven alginate ~ibre webs having a high degree of inter-fibre bonding as produced by the process of W0 80/02300 form a~ relatively harsh fabric likely to be very stiff and to have poor handling qualities, especially if one attempts to make up such webs into thick or multilayer fabricsg and this severely limits the usefulness of such material at least in this field of products for surgical and medical purposes.
In carrying out the invention, the treatment step for eliminating or reducing inter-fibre bonding may comprise subJecting the dried sheet or web of the overlaid fibres after the de-watering drying operation to mechanical action which mechanically stresses individual fibres and promotes breakage of any bonds existing therebetween.
Alternatively, or in addition~ the treatment may comprise adding a material at an earlier stage of the process which prevents or lnhibits the formation of inter~
3~
fibre bonding ln the de-watering drying operation. Such additive could comprlse a substance, such as emulsified oil for example or even a silicone, introduced before the de-watering drying operatlon and effective to coat the fibres so as to prevent or inhlbit bondin~; or lt may comprise a water soluble organic solvent, for example a lo~rer alkyl alcohol or acetone, ef~ective to exchange at least a proportion of the water carried by the fibres.
In the latter case~ the organic solvent treatment constitutes a stage of the de-watering drylng operation and may be useful in any event, in addition to a mechanical treatment, ~or reducing the amount o~ water which needs to be removed by other drylng means. Eut, by controlling the nature~ a~ount and manner of application of the organic solvent, ~or example by using concentrated alcohol in a counter-current arrangement, the quantity of water exchanged and de-watering effect obtained can ln some cases be suf~icient in itself to prevent the occurrence o~ any signiflcant degree of lnter-fibre bonding ln forming the dried non-woven web.
Adding a coating substance such as an emulsified oil may give greater problems in obtaining a final product of acceptable quality, but if thls method is used the substance is preferably added to coat the wet spun fibres before laying the sheet thereof onto the moving conveyor.
9.~9~3~a In preferred embodiments the treatment by mechanical action is employed, preferably by applying mechanical force to the drled sheet or web to pull and tension the o~erlaid fibres. Such pulling force ls preferably applled lengthwise to the fibres by passlng the sheet or web through successive sheet feeding means~ such as two closely spaced pairs of parallel rollers, the first pair of rollers being driven to provide a feed rate equal to the linear speed of the moving conveyor and the second pair of rollers, which is positioned furthest downstream of the travelling sheet or web, being driven to provide a faster feed rate.
The feed rate of the second pair of such rollers may be matched with approximate equality to the rate at which the sheet of wet spun undried fibres is fed onto the moving conveyor, the action then being merely to break any lnter-fibre bonds and provide a dried non-woven web suitable for gathering into a tow for staple cutting. Or, alternatively, the speed of the second pair of rollers may be such as to give a feed rate which is significantly greater~ for example at least 20~ greater~ than the rate of feeding the sheet of wet spun undried fibres onto the moving conveyor whereby a "stretch-breaklng" effect is obtained yielding a we~ materlal containing randomly broken generally parallel fibres extending lengthwise of the web.
The non-woven web produced by this "stretch-breaking"
;
~9~3~;~
process necessarily has minimal lnter~fibre bondlng and may be similar in appearance to the output from a textile card;
it is generally suitable for the production Or a non-woven multilayer wadding by overlaying~ pre~erably by crosslayln~, a plurality o~ layers of such web material.
Thus, according to this ~urther aspect, the invention also provides a process for the production of dried alginate fibre material which includes the operations of spinning an aqueous solution of a soluble alginate salt lnto a spin bath containing an aqueous solution of a salt, for example a calcium salt, to provide wet spun fibres of insoluble alginate, forming a sheet of the wet spun insoluble undried alginate fibres in which the indivldual fibres are separated and disposed in generally parallel relationship, feeding forwards and laying the sheet of undried fibres onto a moving conveyor device which is travelling at a slower speed than said sheet in the feed direction whereby the fibres become overlaid in crossing-over intersecting relationship to form a web, followed by further processing in which said sheet or web o~intersecting overlaid fibres is sub~ected to a dewatering drying operation~ characterised in that subsequent to the dewatering drying operation the sheet or web o~ overlaid fibres is subjected to a "stretch-breaking" operation to cause said fibres to be randomly broken.
~3~9231~
In making up such non-woven waddlng for sur~ical dressings and the like, the layers of the dried web may be sub~ected to a needllng operatlon or other mechanlcal action effective to assist ln holding the layers together by mechanical interlocking of individual fibres of ad~acent layers; or a controlled degree of flbre bonding between the layers may be introduced by spraying either wlth water (in the case of the web being composed of relatively soluble sodium/calcium mixed salt alginate fibres) or (in the case of the web being composed of insoluble calcium alginate fibres) with an aqueous solution of a salt of an acid which has a water insoluble calcium salt, such as sodium citrate for example, the spray belng controlled in quantity in order to control the degree of bonding between the layers.
Fbr preference~ such spray is applied by means of an airless sprayer.
If staple cut tow is produced, this may be used either to make up a wadding by air laying or to make alginate wool, both being suitable for medical or surgical purposes.
Af`ter the initial spinning operation in the spin bath but before being lald on the moving conveyor, the newly spun alginate fibres are preferably also stretched in order to orientate the alginate molecules in the fibres~ and this stretching is conveniently performed at an elevated 3~
temperature above room temperature by, rOr example, passing the f~bres through a hot water bath.
The sheet of separated and generally parallel undrled wet splm alglnate ~lbres can be ~ormed directly by use o~ a spinning Jet having spinning apertures arranged evenly throughout a narrow rectangular area which may extend for the ~ull working width o~ the spin bath and/or conveyor device. Or, a conventional circular ~et may be used for spinning and the we~ spun fibres, conveniently gathered into the form o~ a tow, may be passed through a spreader which spreads them apart evenly in parallel relationship lnto a substantially uniform thin layer or band for laylng onto the moving conveyor.
In the latter arrangement, it can be advantageous to use a known form o~ spreader comprising a "fish tail"
devlce in which the wet spun fibres are conveyed by a stream of liquid which proceeds from a narrow but relatively deep cross-section entry slot, through a chamber having a cross~section of substantially constant area throughout its length but of progresslvely varying shape~
to a horizontally extending exit slot of the same or very slightly s~aller cross section~ Alternati~ely, the spreader may comprise a mechanical spreader device such as, ~or example, a cambered roller or series of cambered rollers or a cur~ed bar type spreader~
3L3L~3~
In preferred embodiments, the sheet of undrled wet spun alginate fibres ls fed forwards onto the moving conveyor device at a speed wh-lch is at least 20% greater than the speed of travel of the conveyor. Conveniently, the conveyor device is a Fburdrinier mesh conveyor or similar liquid permeable moving belt conveyor.
If it is desired to convert the calcium alginate fibres to the sodium/calcium alginate mixed salt form, this is preferably carried out while the web or sheet is still on the conveyor immediately after the de-watering drying operation carried out on the sheet or web of undried fibres. The conversion is preferably carried out by exchanging a proportion of the calcium ions for sodium ions, this being accomplished by treating the sheet or web with a solution of sodlum acetate in aqueous alcohol solution~ the concentration o~ the alcohol being between 10% and 30% by volume, and finally washing with alcohol before further drying. In performing this exchange treatment9 the sheet or web of the calcium alginate fibres may advantageously be first treated with a measured quantity of an acidic agent, for example acetic acid, in order to remove calcium ions which are to be replaced~ then washed with water and finally exchanged with the aqueous alcoholic solution of sodium acetate to which sodium hydroxide or carbonate or bicarbonate is added to ma~ntain the pH between 5 and 7~ preferably between 5.5 and 6O
~8 ~L~9~36~
In some cases, the web or sheet of dried fibres may also be treated so as to exchange a proportion o~ the metal cations by a cationic radical of an organlc base, such as novocaine (procaine) or lignocaine (xylocalne), having analgeslc propertles.
The controlled treatment step f'or eliminating or reducing bonding o~ the overlaid fibres should be such that in the dried non-woven web o~ the alginate fibre material obtained the tenacity of the web measured in the transverse direction is not more than 25%, and is pre~erably not more than 10%, of the tenaclty measured in the longitudinal direction. Such measurements can be carried out by a standard type of tensile testing instrument, The actual values of tenacity measured will depend of course not only on the degree o~ inter-fibre bonding but also on the density of the material in terms of size and number of fibres or filaments. Generally, however~ for drled webs of alginate fibre material provided by the present invention the tenacity measured in the longitudinal (machine) direction wlll be at least 5g/cm per gram per square metre basis weight (e.g. 300g/cm for alginate web material of 60g.s.m.) whereas the tenacity measured ln the transverse or cross direction wlll be not more than 1.25g/cm for the same basis weight (e.g~ 75g/cm again for materlal 60g.s.m.).
3~L923~
By way of example, the carrying out of the process in accordance ~ith the lnvention will be further described with reference to the accompanying drawlng which is a diagrammatic represenkation of apparatus suitable for use in the process.
First, in a spinning machine (not shown) a continuous tow o~ calcium alginate fibres is produced by spinning an aqueous solution of sodium alginate into an aqueous solution of calcium ions. The fibres are glven the necessary mechanical properties by orienting the molecules by stretching as in conventional synthetic fibre spinning, this preliminary stretching being for preference performed at an elevated temperature and for conven~ence and control this may be achieved by running the tow through a bath of hot water before thls stretching stage.
Some method of control of the biodegradation of the spinning solution is also required and this is for pre~erence provided by treatment of the solution with sodium hypochlorite at a dosage of 1 - 10% (pre~erably 3%) available chlorine on sodium alginate. Also, the spinning solution will generally be allowed to stand for a period before spinning in order to deaerate.
Referring now to the drawing, the tow 10 so produced is fed from the spinning machlne into a spreader 12 ~:~9Z3~i~
designed to separate all the fibres into a thin sheet of parallel lndividual fibres. The device consists of a spreader box or tank 14, below a header roll 16, through which water flows from an inlet 18. The tank has at its base an exit 20. This exlt 20 i3 connected to a flsh-tail 22~ the cross-section of which is substantially constant over its length but which varies from a narrow deep vertical slot of approximately rectangular shape at the entry point to a wide3 shallow horizontal slot of approximately rectangular shape at its outlet 24~ The word "approximately" is to be taken in this context to mean that the corners may be rounded. Use of a spreader of this form is an alternative to another possible arrangement in which a spinning ~et is provided of rectangular shape having its spinning holes spaced evenly within a narrow band extending across the full width of the spin bath and/or the ~ollowing moving conveyor device.
The spread tow is fed onto a Fourdrinier wire mesh conveyor 26, constituting the moving conveyor device, at an overfeed speed, thus giving a looping or crimping and overlaying o~ the fibres and destroying their parallel orientation, the fibres then lying in crossing-over intersecting relationship forming a sheet or web 25. The ~burdrinier includes drive rolls 28, 30g and a water dralnage receptacle 32.
..
3~
The sheet or web on the ~burdrinier may then be exchanged with a water soluble organlc solvent ~ preferably alcohol or industrial methylated spirit (I~MoS~ ) ~ applied through sprays 34 and collected ln troughs 36. Although thi~ stage is not essential in this particular embodlment~
the higher the final alcohol level, the less the inter-fibre adhesion and bonding obtained, and the lower the evaporative load on the ~ollowing evaporative drying devices. An alcohol level of greater than 50% v/v in the ~inal wash is preferred.
The web is then dried in this embodiment by a hot air drier 38 in a recirculatory air system. This arrangement avoids lmposing any mechanical forces on the web which would promote fibre-fibre bondinæ. For the same reason, it wlll be noted that no suction device is used for removing water, and the web is not passed over pressure rolls before or during drying.
If it is desired to convert the dried web to the more soluble sodium/calcium mixed salt form which is preferred for many uses, the web is next first treated with a measured amount of acetic acid (or HCl) to remove that proportion of calcium ions which will be replaced by sodium ions. Excess acid is removed by washing with water. Then the web is treated with a solution of sodium acetate in a - 20% v/v I.M.S./water mlxture. The acetic acid
The present lnvention relates to a process for the production of alginate fibres~ particularly dried alginate ~lbre materlal, and to products made therefrom~ it is especially, although not exclus~vely, useful for the commercial manufacture and preparatlon of materlals and products, composed of alginate ~ibres, for use as swabs or dresslngs and the like suitable for medical, surgical and other purposes.
10The extrusion of alginate solutions into coagulating baths or spin baths containing for example aqueous solutlons providing calcium ions to form or spin yarns of insoluble alginate salt filaments ls a well known process.
15It is also well known to prepare and use materials or fabrics composed of alginate flbres, especially calcium and sodium/calclum mlxed salt alginate ~ibres, for surgical and medical purposes, for instance in the form Or dressings and the like in connection with which the haemostatic properties of the alginate and, in some casesJ solubillty ln body fluids can be partlcularly valuable. Such uses are for example described in British Patents Nos. 653341 and 1394741.
25In the past, alginate fabrics for providing surgical and medical dressing~ and the like have generally been produced ~rom continuous calciu~ alginate filament yarn by 36~
knltting~ When the alginake material is required in the more soluble sodlum/calcium mixed salt ~orrn, which is commonly preferred and is mor-e useful ln many cases, the knitted fabric ls then treated or "converted" to replace part o~ the calcium content by the more solubili3ing sodlum cation.
This converslon o~ the calcium alginate to the more soluble sodium/calcium alginate mixed salt form ls the subJect of a number o~ Patent publications and an excellent summary is glven in Britiqh Patent No. 1394741 which sets out the basis for a process whlch ls technically superior to previous methodsO In practice, however, the treatment or conversion process performed on the knitted fabric has usually involved handling problems and has been carried out batchwise whlch is rather ine~ficient and uneconomic resulting in a costly and wasteful production process.
As wlll be seen later~ the process of the preeent invention can enable calcium alginate fibres to be wet spun and processed to ~orm a dried alginate fibre material in a continuous series of operations which can include, when required5 a step of convertlng the calcium alginate fibr-e materlal into the sodium/calcium mixed salt form. The dried alginate fibre material so fvrmed may then be made up into a tow suitable for swab production or alginate wool or into the ~orm o~ a non-woven wadding suitable for use as a 3~
medical or surgical dressing. The entire process can be performed without handling the material, using simple machinery which ls easy to maintain to the standards of cleanliness required of this type of product.
A factor to be considered 9 however, in the production and processing of alginate fibres is the tendency of such fibres~ when wet, to adhere and fuse together on drylng.
This tendency is of ma~or importance in the drying of wet newly-spun "never-drled" alginate ~ibres since these are extremely soft and have a very high water content so thatJ
during drying, considerable dewatering takes place and ad~acent individual fibres or filaments are caused to adhere to each other by capillary action and become bonded together. This bonding effect can be dramatically increased by any mechanical forces externally applied at the dewatering drying stageO
It may be noted that this tendency for inter-~ibre bonding to occur is not so important in drying "re-wetted"
alginate flbres~ that is, alginate fibres or yarns which have been dried after being lnitially spun and which have then subsequently been re-wetted~ In the latter case 3 provided a significant degree of fibre bonding has been avoided ln first producing and drying the fibres it is found that on subsequent re-wetting considerably less water is taken up by the fibres and during re-drying the tendency ~Z3~;~
for the fibres to adhere and bond together is very much reduced. On the other hand, in any continuous productlon process which starts with the inltial step of wet spinnlng calcium alglnate fibre filaments one ls necessarily deallng wlth "never-dried" alglnate flbres whlch remaln wet up to the drying stage at whlch the tendency to adhere and bond together arlses as discussed above.
In the commercial productlon of contlnuous drled alginate filament yarns the problem of excessive and undesirable bonding between individual ~ibre ~ilaments may be overcome by coating the fllaments before drylng with a substance such as an emulsified oil which prevents the filaments from sticking together. Or, as an alternative remedyS flbre adhesion may be inhibited by exchanglng and removing the waker with an organ-lc water soluble solvent such as acetone or a lower alcohol at a su~ficiently hlgh concentration.
It has been already-dried alglnate ~ilament yarns as referred to above which have previously been commonly used for making knitted alginate fabrics in the conventional processes for providing surgical and medical alginate dressings. It has, howeverg also been proposed in 25 publication document WO 80/02300 of International Patent Application No. PCT/GE80/00066 (Courkaulds Limited) to provide a non~woven alginate fabric for use as an alginate 3`~
dressing and a process for the production of such non-woven fabric is disclosed therein.
According to the process of W0 80/02300, a tow of stretched and washed spun calcium alginate ~ibres or filaments is passed in a flow of water through a spreading device, such as a device with a "fish tail" outlet, and the spread band or sheet produced is fed forwards and deposited on a liquid permeable conveyor, such as a Fourdrinier wire mesh conveyor, moving at a slower speed so that the fibres are overlaid in a substantially uniform layer or sheet forming a web whlch iæ then dried to provide a unitary non-woven alginate fabric. As a result of the overlaying, the fibres become crimped or looped and cross over each other in the web so that a parallel orientation thereof is destroyed; it will be appreciated that this reduces the contact area~of the fibres and prevents the ~ormation, in the subsequent dewatering drying operation, of a sheet in which parailel fibres are bonded and fused together along their length. Such a sheet of parallel bonded alginate fibres would be completely unsuitable for medical or surgical alginate dressings.
The advantages resulting from overlaying the fibres as described above suggests that no other special measures need to be taken to counteract bonding together of the fibres. Indeed, on the contrary, the disclosure in W0 3~
80/02300 indicates that some fibre bonding is desirable and particularly emphasises that although lengthwlse bonding is avolded the overlaid ~ibres in the web produced should still be bonded at their points of contact where they cross over each other; the drying operatlon in the process described accordingly is carried out in a way which applies mechanical forces and promotes such bonding at intersections, first by applying suction directly to the wet overlald fibres on the conveyor and then by passing the partially dried web around heated cylinders. Also, a way of further lncreasing the degree of such inter-bonding by a treatment of the filaments on the conveyor with an aqueous solution of a sodium salt, preferably a sodium salt o~ an acid which forms on insoluble calcium salt, before completlng the drying operation is described. A non-woven alginate fabric is thus produced by the process of W0 80/02300 consisting essentially of a dried web of intersecting alginate fibres or filaments bonded together at their cross-over points to provide a strong unitary structure~
The production of non woven unitary webs or fabrics directly from tows of continuous synthetic textile filaments is also already known from U.S. Patent No.
3802980 ~Harmon) which describes a manufacturing process similar in some ways to that described in W0 80/02300, especially in respect of the use of a fish-tail type ~92~6~
spreader to overfeed onto a more slowly moving liquid permeable conveyor a thin sheet or band of filaments or fibres so that the latter become crimped and overlald in crossin~-over or intersecting overlapplng relationship in a continuous fllament sheet which i8 then dried to produce the non-woven unitary web required. The flbres or filaments of the web produced are not described as being bonded and it is implied that frictional engagement between overlapping crimped or looped fibre portions of ad~acent individual filaments suffices to maintain a unitary structure. This may be so~ although it is notable that in the specific examples descrlbed the fllament sheet on the conveyor is sprayed before final drying with a polyvinyl alcohol solution which is known to act as an adhesive and promote bonding to some extent with many fibres.
In any event, the process of U.S. Patent No. 3802980 is not specifically described ~s being applied to alginate ~lbres or filaments but appears to be directed more to synthetlc textile ~ilaments such as viscose rayon, nylon~
polyesters, acrylics and polyoleflns etc., and it can be inferred that the lnitial tows to which lt is expected that the process would be applied would be composed of already dried continuous filaments of these materials. If~ on the other hand, the process were to be applied to "never dried'i alginate ~ibres and carried out exactly as described uslng in particular a suction box to remove water from the - - -freshly laid sheet or web on the conveyor, a high deyree of bonding between the fibres or filaments at their cross-over points would inevitably be obtained as in the process of WO
80/02300. This, however, would be quite in accordance with the teaching of the latter and may therefore well be considered to represent a useful advantage.
The process of the present invention has some features in common with that described in WO 80/02300 but it differs in certain very significant respects and there is a fundamental difference in that it departs completely from the teaching of the latter in regard to endeavouring to produce as an end product a unitary non-woven web or fabric composed of a drieA sheet o~ overlaid alginate fibres or filaments which are bonded together where they intersect and cross over each other. On the contrary, the present invention seeks to provide a process, which can be continuously operable, adapted to produce a unitary dried non-woven web of non-bonded algina-te fibres.
Thus, according to the present invention, there is provided a process for the production of dried alginate fib~e material 0 whi~h includes the operations of spinning an aqueous solution of a soluble alginate salt into a spin bath containing an aqueous solution of a salt which provides wet spun fibres of insoluble alginates, forming a sheet of the wet spun insoluble undried alginate fibres in which the individual fibres are separated and disposed in generally parallel relationship, feeding forwards and laying the sheet of undried fibres onto a moving conveyor device which is travelling at a slower speed than said sheet in the feed direction whereby the fibres become overlaid in crosslng-over intersecting relationship to form a sheet-like webl and subjecting said sheet-like web of intersecting overlaid fibres to a dewatering drying operation, _ g _ ~9~3~
wherein the process also includes measures ef~ective to inhibit the occurrence of bonding together of the overlaid crossing-over fibres at their points of contact in the sheet-like web during the dewatering drying operation and wherein, subsequent to the dewatering drying operation, the sheet-like web of overlaid fibres while still in said sheet form is subjected to a "stretch-breaking" operation effective to cause said ibres in the web to be randomly broken.
It will be appreciated that in the present specification the term "web" is used in a broad sense to include any sheet-like layer or matrix of individual fibres and it does not imply that there is necessarily some significant degree of actual bonding or strong permanent adhes.ion between the individual fibres thereof.
It has been found that, despite the teaching of WO
8Q/02300, dried non-wover alginate fibre webs made in accordance with the present invention so as to have but a a~. ~
36~
minimal degree of bondlng between the fibres afford a material which, for the purpose of providing products such as surgical or medical dressings and swabs and the like, is in general much superlor to that a~forded by dried non-woven alginate fibre webs havlng a high degree of flbre-fibre bonding.
This superiority arises primarily from the fact that the webs made in accordance with the invention with minimal inter fibre bonding present a significantly softer texture and of~er greater scope for various dif~erent finishing operations in preparing or making up final materials or products having desired characteristics for surgical or medical use. As will hereinafter be apparent, a range of options is available for further processlng these webs of dried alginate fibre material for the purposes required, including making up lnto comparatively thick multilayer ~abrlcs by cross-laying and introducing a carefully controlled amount of bonding between layers to provide soft non-woven wadding, and forming or gathering into a tow of separate and substantially parallel fibres which can then be staple cut and used to make wadding by air laying or to make alginate wool with a further option o~ introducing and blending with other different fibres.
Advantageously in some cases, as hereinafter described in accordance with a further aspect of the ~9~3~
invention, the fibres of such webs may also be randomly broken by a stretch breaking operation before being made up for example into a cross-laid multilayer fabric for waddlng, this stretch breaking yielding material of non-bonded fibres which may be similar to that produced by akextile card.
In contrast with the material obtained by means of the present invention, non-woven alginate ~ibre webs having a high degree of inter-fibre bonding as produced by the process of W0 80/02300 form a~ relatively harsh fabric likely to be very stiff and to have poor handling qualities, especially if one attempts to make up such webs into thick or multilayer fabricsg and this severely limits the usefulness of such material at least in this field of products for surgical and medical purposes.
In carrying out the invention, the treatment step for eliminating or reducing inter-fibre bonding may comprise subJecting the dried sheet or web of the overlaid fibres after the de-watering drying operation to mechanical action which mechanically stresses individual fibres and promotes breakage of any bonds existing therebetween.
Alternatively, or in addition~ the treatment may comprise adding a material at an earlier stage of the process which prevents or lnhibits the formation of inter~
3~
fibre bonding ln the de-watering drying operation. Such additive could comprlse a substance, such as emulsified oil for example or even a silicone, introduced before the de-watering drying operatlon and effective to coat the fibres so as to prevent or inhlbit bondin~; or lt may comprise a water soluble organic solvent, for example a lo~rer alkyl alcohol or acetone, ef~ective to exchange at least a proportion of the water carried by the fibres.
In the latter case~ the organic solvent treatment constitutes a stage of the de-watering drylng operation and may be useful in any event, in addition to a mechanical treatment, ~or reducing the amount o~ water which needs to be removed by other drylng means. Eut, by controlling the nature~ a~ount and manner of application of the organic solvent, ~or example by using concentrated alcohol in a counter-current arrangement, the quantity of water exchanged and de-watering effect obtained can ln some cases be suf~icient in itself to prevent the occurrence o~ any signiflcant degree of lnter-fibre bonding ln forming the dried non-woven web.
Adding a coating substance such as an emulsified oil may give greater problems in obtaining a final product of acceptable quality, but if thls method is used the substance is preferably added to coat the wet spun fibres before laying the sheet thereof onto the moving conveyor.
9.~9~3~a In preferred embodiments the treatment by mechanical action is employed, preferably by applying mechanical force to the drled sheet or web to pull and tension the o~erlaid fibres. Such pulling force ls preferably applled lengthwise to the fibres by passlng the sheet or web through successive sheet feeding means~ such as two closely spaced pairs of parallel rollers, the first pair of rollers being driven to provide a feed rate equal to the linear speed of the moving conveyor and the second pair of rollers, which is positioned furthest downstream of the travelling sheet or web, being driven to provide a faster feed rate.
The feed rate of the second pair of such rollers may be matched with approximate equality to the rate at which the sheet of wet spun undried fibres is fed onto the moving conveyor, the action then being merely to break any lnter-fibre bonds and provide a dried non-woven web suitable for gathering into a tow for staple cutting. Or, alternatively, the speed of the second pair of rollers may be such as to give a feed rate which is significantly greater~ for example at least 20~ greater~ than the rate of feeding the sheet of wet spun undried fibres onto the moving conveyor whereby a "stretch-breaklng" effect is obtained yielding a we~ materlal containing randomly broken generally parallel fibres extending lengthwise of the web.
The non-woven web produced by this "stretch-breaking"
;
~9~3~;~
process necessarily has minimal lnter~fibre bondlng and may be similar in appearance to the output from a textile card;
it is generally suitable for the production Or a non-woven multilayer wadding by overlaying~ pre~erably by crosslayln~, a plurality o~ layers of such web material.
Thus, according to this ~urther aspect, the invention also provides a process for the production of dried alginate fibre material which includes the operations of spinning an aqueous solution of a soluble alginate salt lnto a spin bath containing an aqueous solution of a salt, for example a calcium salt, to provide wet spun fibres of insoluble alginate, forming a sheet of the wet spun insoluble undried alginate fibres in which the indivldual fibres are separated and disposed in generally parallel relationship, feeding forwards and laying the sheet of undried fibres onto a moving conveyor device which is travelling at a slower speed than said sheet in the feed direction whereby the fibres become overlaid in crossing-over intersecting relationship to form a web, followed by further processing in which said sheet or web o~intersecting overlaid fibres is sub~ected to a dewatering drying operation~ characterised in that subsequent to the dewatering drying operation the sheet or web o~ overlaid fibres is subjected to a "stretch-breaking" operation to cause said fibres to be randomly broken.
~3~9231~
In making up such non-woven waddlng for sur~ical dressings and the like, the layers of the dried web may be sub~ected to a needllng operatlon or other mechanlcal action effective to assist ln holding the layers together by mechanical interlocking of individual fibres of ad~acent layers; or a controlled degree of flbre bonding between the layers may be introduced by spraying either wlth water (in the case of the web being composed of relatively soluble sodium/calcium mixed salt alginate fibres) or (in the case of the web being composed of insoluble calcium alginate fibres) with an aqueous solution of a salt of an acid which has a water insoluble calcium salt, such as sodium citrate for example, the spray belng controlled in quantity in order to control the degree of bonding between the layers.
Fbr preference~ such spray is applied by means of an airless sprayer.
If staple cut tow is produced, this may be used either to make up a wadding by air laying or to make alginate wool, both being suitable for medical or surgical purposes.
Af`ter the initial spinning operation in the spin bath but before being lald on the moving conveyor, the newly spun alginate fibres are preferably also stretched in order to orientate the alginate molecules in the fibres~ and this stretching is conveniently performed at an elevated 3~
temperature above room temperature by, rOr example, passing the f~bres through a hot water bath.
The sheet of separated and generally parallel undrled wet splm alglnate ~lbres can be ~ormed directly by use o~ a spinning Jet having spinning apertures arranged evenly throughout a narrow rectangular area which may extend for the ~ull working width o~ the spin bath and/or conveyor device. Or, a conventional circular ~et may be used for spinning and the we~ spun fibres, conveniently gathered into the form o~ a tow, may be passed through a spreader which spreads them apart evenly in parallel relationship lnto a substantially uniform thin layer or band for laylng onto the moving conveyor.
In the latter arrangement, it can be advantageous to use a known form o~ spreader comprising a "fish tail"
devlce in which the wet spun fibres are conveyed by a stream of liquid which proceeds from a narrow but relatively deep cross-section entry slot, through a chamber having a cross~section of substantially constant area throughout its length but of progresslvely varying shape~
to a horizontally extending exit slot of the same or very slightly s~aller cross section~ Alternati~ely, the spreader may comprise a mechanical spreader device such as, ~or example, a cambered roller or series of cambered rollers or a cur~ed bar type spreader~
3L3L~3~
In preferred embodiments, the sheet of undrled wet spun alginate fibres ls fed forwards onto the moving conveyor device at a speed wh-lch is at least 20% greater than the speed of travel of the conveyor. Conveniently, the conveyor device is a Fburdrinier mesh conveyor or similar liquid permeable moving belt conveyor.
If it is desired to convert the calcium alginate fibres to the sodium/calcium alginate mixed salt form, this is preferably carried out while the web or sheet is still on the conveyor immediately after the de-watering drying operation carried out on the sheet or web of undried fibres. The conversion is preferably carried out by exchanging a proportion of the calcium ions for sodium ions, this being accomplished by treating the sheet or web with a solution of sodlum acetate in aqueous alcohol solution~ the concentration o~ the alcohol being between 10% and 30% by volume, and finally washing with alcohol before further drying. In performing this exchange treatment9 the sheet or web of the calcium alginate fibres may advantageously be first treated with a measured quantity of an acidic agent, for example acetic acid, in order to remove calcium ions which are to be replaced~ then washed with water and finally exchanged with the aqueous alcoholic solution of sodium acetate to which sodium hydroxide or carbonate or bicarbonate is added to ma~ntain the pH between 5 and 7~ preferably between 5.5 and 6O
~8 ~L~9~36~
In some cases, the web or sheet of dried fibres may also be treated so as to exchange a proportion o~ the metal cations by a cationic radical of an organlc base, such as novocaine (procaine) or lignocaine (xylocalne), having analgeslc propertles.
The controlled treatment step f'or eliminating or reducing bonding o~ the overlaid fibres should be such that in the dried non-woven web o~ the alginate fibre material obtained the tenacity of the web measured in the transverse direction is not more than 25%, and is pre~erably not more than 10%, of the tenaclty measured in the longitudinal direction. Such measurements can be carried out by a standard type of tensile testing instrument, The actual values of tenacity measured will depend of course not only on the degree o~ inter-fibre bonding but also on the density of the material in terms of size and number of fibres or filaments. Generally, however~ for drled webs of alginate fibre material provided by the present invention the tenacity measured in the longitudinal (machine) direction wlll be at least 5g/cm per gram per square metre basis weight (e.g. 300g/cm for alginate web material of 60g.s.m.) whereas the tenacity measured ln the transverse or cross direction wlll be not more than 1.25g/cm for the same basis weight (e.g~ 75g/cm again for materlal 60g.s.m.).
3~L923~
By way of example, the carrying out of the process in accordance ~ith the lnvention will be further described with reference to the accompanying drawlng which is a diagrammatic represenkation of apparatus suitable for use in the process.
First, in a spinning machine (not shown) a continuous tow o~ calcium alginate fibres is produced by spinning an aqueous solution of sodium alginate into an aqueous solution of calcium ions. The fibres are glven the necessary mechanical properties by orienting the molecules by stretching as in conventional synthetic fibre spinning, this preliminary stretching being for preference performed at an elevated temperature and for conven~ence and control this may be achieved by running the tow through a bath of hot water before thls stretching stage.
Some method of control of the biodegradation of the spinning solution is also required and this is for pre~erence provided by treatment of the solution with sodium hypochlorite at a dosage of 1 - 10% (pre~erably 3%) available chlorine on sodium alginate. Also, the spinning solution will generally be allowed to stand for a period before spinning in order to deaerate.
Referring now to the drawing, the tow 10 so produced is fed from the spinning machlne into a spreader 12 ~:~9Z3~i~
designed to separate all the fibres into a thin sheet of parallel lndividual fibres. The device consists of a spreader box or tank 14, below a header roll 16, through which water flows from an inlet 18. The tank has at its base an exit 20. This exlt 20 i3 connected to a flsh-tail 22~ the cross-section of which is substantially constant over its length but which varies from a narrow deep vertical slot of approximately rectangular shape at the entry point to a wide3 shallow horizontal slot of approximately rectangular shape at its outlet 24~ The word "approximately" is to be taken in this context to mean that the corners may be rounded. Use of a spreader of this form is an alternative to another possible arrangement in which a spinning ~et is provided of rectangular shape having its spinning holes spaced evenly within a narrow band extending across the full width of the spin bath and/or the ~ollowing moving conveyor device.
The spread tow is fed onto a Fourdrinier wire mesh conveyor 26, constituting the moving conveyor device, at an overfeed speed, thus giving a looping or crimping and overlaying o~ the fibres and destroying their parallel orientation, the fibres then lying in crossing-over intersecting relationship forming a sheet or web 25. The ~burdrinier includes drive rolls 28, 30g and a water dralnage receptacle 32.
..
3~
The sheet or web on the ~burdrinier may then be exchanged with a water soluble organlc solvent ~ preferably alcohol or industrial methylated spirit (I~MoS~ ) ~ applied through sprays 34 and collected ln troughs 36. Although thi~ stage is not essential in this particular embodlment~
the higher the final alcohol level, the less the inter-fibre adhesion and bonding obtained, and the lower the evaporative load on the ~ollowing evaporative drying devices. An alcohol level of greater than 50% v/v in the ~inal wash is preferred.
The web is then dried in this embodiment by a hot air drier 38 in a recirculatory air system. This arrangement avoids lmposing any mechanical forces on the web which would promote fibre-fibre bondinæ. For the same reason, it wlll be noted that no suction device is used for removing water, and the web is not passed over pressure rolls before or during drying.
If it is desired to convert the dried web to the more soluble sodium/calcium mixed salt form which is preferred for many uses, the web is next first treated with a measured amount of acetic acid (or HCl) to remove that proportion of calcium ions which will be replaced by sodium ions. Excess acid is removed by washing with water. Then the web is treated with a solution of sodium acetate in a - 20% v/v I.M.S./water mlxture. The acetic acid
2~
~923~
released is neutralised by additon of NaOH or Na CO at such a rate that the pH is kept in the range 5.5 to 6.o.
This conversion ls extremely rapid since it relles on exchange of sodium ions from a fully ionised solution o~ a sodlum salt in concentrationæ in excess of N/10~ rather than neutralisation by solutions o~ hydroxyl ions whose concentration is severely restrlcted by the necesslty to ~eep the pH below about 9Ø The converted web is ~inally washed with I.M.S. and then dried with a further hot air drier (not illustrated) as previously described.
I~ it is not desired to convert to the sodium/calcium roixed salt ~orm so that the web remains composed of insoluble calcium alginate fibres, the above stage is omitted.
In the following stage, the dried web of ~ibres, shown at 50, is pulled or stretched by passing lt through two pairs of parallel rollers 40, 42g whose axes are placed as close to each other as possible, the second pair 42 rotating slightly faster than the ~irst pair 40. If the circum~erentlal speed o~ the second pair o~ rollers 42 is the same as the feed rate of the tow through the spreader and ~ish tail, any bonding at ~ibre crossover points will be broken, and the result will be a sheet or web of continuous individual ~ilament ~ibres extending lengthwise of the web~ Howeverg if the s~eed of the second palr of
~923~
released is neutralised by additon of NaOH or Na CO at such a rate that the pH is kept in the range 5.5 to 6.o.
This conversion ls extremely rapid since it relles on exchange of sodium ions from a fully ionised solution o~ a sodlum salt in concentrationæ in excess of N/10~ rather than neutralisation by solutions o~ hydroxyl ions whose concentration is severely restrlcted by the necesslty to ~eep the pH below about 9Ø The converted web is ~inally washed with I.M.S. and then dried with a further hot air drier (not illustrated) as previously described.
I~ it is not desired to convert to the sodium/calcium roixed salt ~orm so that the web remains composed of insoluble calcium alginate fibres, the above stage is omitted.
In the following stage, the dried web of ~ibres, shown at 50, is pulled or stretched by passing lt through two pairs of parallel rollers 40, 42g whose axes are placed as close to each other as possible, the second pair 42 rotating slightly faster than the ~irst pair 40. If the circum~erentlal speed o~ the second pair o~ rollers 42 is the same as the feed rate of the tow through the spreader and ~ish tail, any bonding at ~ibre crossover points will be broken, and the result will be a sheet or web of continuous individual ~ilament ~ibres extending lengthwise of the web~ Howeverg if the s~eed of the second palr of
3~
rollers 42 is further increased the fibres will be stretch-broken ln the same manner that happens in conventional break-spinning of textile fibres. The result is then to produce a thin web of flbre material, very similar in appearance to that derived from carding staple fibre. The loops lmparted to the fibres by laying on the Fburdrinier as described result in the fibres even after drying being slightly crimped, and this contributes to the unitary web forming properties thereof in the absence of actual inter-fibre bonding.
~ y arranging for the drive speeds of the rollers tobe ad~ustable during operation to vary the relatlve feed rates, the degree of "stretch-breaking" produced can be controlled.
In the drawing, the linear speed of the incoming tow 10 to and through the spreader 12 is denoted by V ~ that of the Fburdrir.ier conveyor and the circumferential speed of the first pull rolls 40 is denoted by V , and the circumferential speed of the second pull rolls 42 is denoted by V . It follows, therefore, that in carrying out the process in this embodiment V ~ V and V ~ V .
The dried alglnate ~ibre material provided by the dried non-woven web of fibres, indicated at 50'g derived 3~
from the abo~e pulling stage forms the initial end product of the process described but it can then be further processed to make up various preparations especlally suitable for medical or surgical use.
Thus, the material can then be made into a wadding, preferably by cross-laying a plurality of layers which, incidentally, will tend to make unimportant any non-uniformlty of the web across its width. A controlled degree of bonding between the layers may be introduced by use of a controlled supply of water, applied by an airless sprayer or, preferably, by sub~ecting the material to a needling operation or other mechanical action e~ective to interengage flbres of adjacent layers and hold the layers together. Such mechanical action, by its effect in mechanically stressing individual fibres, can also promote breakage o~ any residual inter-fibre bonding remaining within each indivldual layer. The resulting wadding is suitable ~or packlng as surglcal dressings without further treatment4 In the event that it should be required to produce a "adding from material composed of insoluble calcium alginate fibres rather than of fibres of the more soluble sodium/calcium mixed salt form~ instead of using a water spray for achieving interlaqer bonding as mentioned above the latter may be substituted by a spray of an aqueous .:
~9'~3~
solution of a sodium salt, of whlch the corresponding calcium salt ls insoluble ln water~ for example sodium citrate.
Should the ~ibre material be requlred in a form suitable for wool or for blending with diluent fibres the dried web ~rom the pulling stage may simply be gathered into a tow which can then be staple cut. Or, as previously indicated, such staple cut tow can be made up into comparatively thick wadding, by using for example an air laying technique, and if desired other kinds of fibres can be mixed in as a diluent at this stage.
rollers 42 is further increased the fibres will be stretch-broken ln the same manner that happens in conventional break-spinning of textile fibres. The result is then to produce a thin web of flbre material, very similar in appearance to that derived from carding staple fibre. The loops lmparted to the fibres by laying on the Fburdrinier as described result in the fibres even after drying being slightly crimped, and this contributes to the unitary web forming properties thereof in the absence of actual inter-fibre bonding.
~ y arranging for the drive speeds of the rollers tobe ad~ustable during operation to vary the relatlve feed rates, the degree of "stretch-breaking" produced can be controlled.
In the drawing, the linear speed of the incoming tow 10 to and through the spreader 12 is denoted by V ~ that of the Fburdrir.ier conveyor and the circumferential speed of the first pull rolls 40 is denoted by V , and the circumferential speed of the second pull rolls 42 is denoted by V . It follows, therefore, that in carrying out the process in this embodiment V ~ V and V ~ V .
The dried alglnate ~ibre material provided by the dried non-woven web of fibres, indicated at 50'g derived 3~
from the abo~e pulling stage forms the initial end product of the process described but it can then be further processed to make up various preparations especlally suitable for medical or surgical use.
Thus, the material can then be made into a wadding, preferably by cross-laying a plurality of layers which, incidentally, will tend to make unimportant any non-uniformlty of the web across its width. A controlled degree of bonding between the layers may be introduced by use of a controlled supply of water, applied by an airless sprayer or, preferably, by sub~ecting the material to a needling operation or other mechanical action e~ective to interengage flbres of adjacent layers and hold the layers together. Such mechanical action, by its effect in mechanically stressing individual fibres, can also promote breakage o~ any residual inter-fibre bonding remaining within each indivldual layer. The resulting wadding is suitable ~or packlng as surglcal dressings without further treatment4 In the event that it should be required to produce a "adding from material composed of insoluble calcium alginate fibres rather than of fibres of the more soluble sodium/calcium mixed salt form~ instead of using a water spray for achieving interlaqer bonding as mentioned above the latter may be substituted by a spray of an aqueous .:
~9'~3~
solution of a sodium salt, of whlch the corresponding calcium salt ls insoluble ln water~ for example sodium citrate.
Should the ~ibre material be requlred in a form suitable for wool or for blending with diluent fibres the dried web ~rom the pulling stage may simply be gathered into a tow which can then be staple cut. Or, as previously indicated, such staple cut tow can be made up into comparatively thick wadding, by using for example an air laying technique, and if desired other kinds of fibres can be mixed in as a diluent at this stage.
Claims (32)
1. A process for the production of dried alginate fibre material which includes the operations of spinning an aqueous solution of a soluble alginate salt into a spin bath containing an aqueous solution of a salt which provides wet spun fibres of insoluble alginates, forming a sheet of the wet spun insoluble undried alginate fibres in which the individual fibres are separated and disposed in generally parallel relationship, feeding forwards and laying the sheet of undried fibres onto a moving conveyor device which is travelling at a slower speed than said sheet in the feed direction whereby the fibres become overlaid in crossing-over intersecting relationship to form a sheet-like web, and subjecting said sheet-like web of intersecting overlaid fibres to a dewatering drying operation, wherein the process also includes measures effective to inhibit the occurrence of bonding together of the overlaid crossing-over fibres at their points of contact in the sheet-like web during the dewatering drying operation and wherein, subsequent to the dewatering drying operation, the sheet-like web of overlaid fibres while still in said sheet form is subjected to a "stretch-breaking" operation effective to cause said fibres in the web to be randomly broken.
2. A process as claimed in Claim 1 wherein the "stretch-breaking" operation is carried out by applying mechanical force over the width of the sheet-like web to pull and tension the overlaid fibres lengthwise, producing thereby a thin web of fibre material resembling material derived from carding staple fibre.
3. A process as claimed in Claim 2 wherein the mechanical force is applied by passing the sheet-like web through successive sheet-feeding means driven to provide different feed rates.
4. A process as claimed in Claim 3 wherein the sheet-feeding means is adjustable during operation to vary the relative feed rates and control the degree of "stretch-breaking".
5. A process as claimed in Claim 3 wherein the sheet feeding means disposed furthest downstream of the travelling sheet-like web, which means provides the faster feed rate, is driven so that said faster feed rate is at least 20% greater than the rate at which the sheet of wet spun undried fibres is fed onto the moving conveyor as to produce the "stretch-breaking" effect yielding fibre material containing randomly broken fibres extending lengthwise thereof.
6. A process as claimed in Claim 2 in which the sheet or web of undried overlaid fibres while on the moving conveyor is treated with a water soluble organic solvent, for example a lower alkyl alcohol or acetone, effective to exchange at least a proportion of the water carried by said fibres, this treatment constituting a stage of the dewatering drying operation.
7. A process as claimed in Claim 6 wherein the treatment with the water soluble organic solvent is controlled in respect of the nature, amount and manner of application of the organic solvent such that the quantity of water exchanged and dewatering effect obtained is sufficient in itself to prevent the occurrence during drying of the sheet or web of any significant degree of inter-fibre bonding of the overlaid fibres at their points of contact or intersection.
8. A process as claimed in Claim 7 wherein the treatment with the water soluble organic solvent is carried out in a counter-current exchange arrangement.
9. A process as claimed in Claim 1 in which the wet spun undried fibres prior to the dewatering drying operation are coated with a substance effective to inhibit inter-fibre bonding and to prevent the occurrence of any significant degree of such bonding at the points of contact or intersection of the overlaid fibres during the subsequent dewatering drying operation.
10. A process as claimed in Claim 9 wherein the coating substance is an oil applied as an additive in emulsified form to the wet spun fibres before laying the sheet of the latter onto the moving conveyor.
11. A process as claimed in Claim 1 wherein the dewatering drying operation is carried out on the conveyor without direct application to the fibre sheet or web of suction, or of heated drying cylinders, or of any other means calculated to subject the fibres to significant mechanical forces effective to promote bonding therebetween.
12. A process as claimed in Claim 1 in which the sheet of separated and generally parallel undried alginate fibres is formed by passing a tow of the wet spun fibres through a spreader which spreads them apart evenly into a substantially uniform thin layer or band for laying onto the moving conveyor.
13. A process as claimed in Claim 12 wherein the spreader comprises a "fish tail" device in which the wet spun fibres are conveyed by a stream of liquid through a chamber having a cross-section of substantially constant area throughout its length but of progressively varying shape from a vertically extending entrance slot to a horizontally extending exit slot.
14. A process as claimed in Claim 1 in which the wet spun alginate fibres are stretched after the spin bath but before being laid on the conveyor thereby to orientate the alginate molecules in the fibres.
15. A process as claimed in Claim 14 wherein the stretching is performed at a temperature elevated above ambient room temperature.
16. A process as claimed in Claim 15 wherein the stretching is performed by passing the fibres through a hot water bath.
17. A process as claimed in Claim 1 in which the sheet of separated and generally parallel undried wet spun alginate fibres is formed directly by use of a spinning jet having spinning apertures arranged evenly throughout a narrow rectangular area.
18. A process as claimed in Claim 1 wherein the sheet of undried wet spun alginate fibres is fed forwards onto the moving conveyor device at a speed which is at least 20%
greater than the speed of travel of said conveyor.
greater than the speed of travel of said conveyor.
19. A process as claimed in Claim 1 wherein the moving conveyor device is a liquid permeable conveyor, for example a Fourdrinier mesh conveyor.
20. A process as claimed in Claim 1 wherein after the dewatering operation, which is carried out on the sheet or web of undried overlaid wet spun fibres on the conveyor device, the resulting web or sheet of dried fibres is treated so as to exchange a proportion of the cations forming the insoluble alginate fibres for alkali metal cations thereby to convert the fibres into a more soluble mixed alginate salt form.
21. A process as claimed in Claim 20 wherein the cation exchange and conversion step is carried out by treating the web or sheet of dried fibres with a solution of sodium acetate in aqueous alcohol.
22. A process as claimed in Claim 21 wherein the web or sheet of dried fibres is first treated with a measured quantity of acetic acid or other acidic agent before the treatment with the sodium acetate solution, and during the latter treatment the pH is maintained between 5 and 7.
23. A process as claimed in any one of Claims 20 to 22 wherein the web is subjected to said "stretch-breaking"
operation after carrying out said cation exchange and conversion step.
operation after carrying out said cation exchange and conversion step.
24. A process as claimed in Claim 1 wherein, after the dewatering drying operation, the web or sheet of dried fibres is treated so as to exchange a proportion of the cations by a cationic radical of an organic base having analgesic properties.
25. A process as claimed in Claim 24 wherein the organic base comprises novocaine or lignocaine.
26. A dried non-woven web of alginate fibres constituting dried alginate fibre material which is the product of a process as claimed in Claim l.
27. A dried non-woven web of alginate fibres as claimed in Claim 26 wherein the tenacity of said web measured in the transverse direction is not more than twenty five per cent (25%) of the tenacity measured in the longitudinal direction.
28. A dried non-woven web of alginate fibres as claimed in Claim 26 wherein the tenacity of said web has a value when measured in the transverse direction which is not more than ten per cent (10%) of the value when measured in the longitudinal direction.
29. A dried non-woven web of alginate fibres as claimed in Claim 26 wherein the tenacity measured in the longitudinal (machine) direction is, per gram per square metre basis weight of material, at least 5g/cm while the tenacity measured in the transverse or cross direction is not more than 1.25g/cm for the same basis weight.
30. A process for producing a medical or surgical preparation comprising producing a dried non-woven web of alginate fibres as claimed in Claim 26, followed by overlaying a plurality of layers of the material of said web to make up a wadding material suitable for medical or surgical purposes.
31. A process as claimed in Claim 30 wherein the layers of said web are cross laid and subjected to a needling operation or other mechanical action effective to interengage fibres of adjacent layers and assist in holding the layers together.
32. A process as claimed in Claim 30, in which a controlled degree of bonding between the layers is introduced by spraying either with a controlled quantity of water in the case of a web composed of relatively soluble sodium/calcium mixed salt alginate fibres or with a controlled quantity of an aqueous solution of a soluble salt of an acid having a water insoluble calcium salt in the case of a web composed of insoluble calcium alginate fibres.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8125178 | 1981-08-18 | ||
| GB8125178 | 1981-08-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1192364A true CA1192364A (en) | 1985-08-27 |
Family
ID=10524017
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000409567A Expired CA1192364A (en) | 1981-08-18 | 1982-08-17 | Process for the production of alginate fibre material and products made therefrom |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US4562110A (en) |
| EP (1) | EP0072680B1 (en) |
| JP (1) | JPS5854059A (en) |
| AT (1) | ATE42974T1 (en) |
| AU (1) | AU546556B2 (en) |
| CA (1) | CA1192364A (en) |
| DE (1) | DE3279686D1 (en) |
| DK (1) | DK351282A (en) |
| GR (1) | GR76271B (en) |
| IE (1) | IE53091B1 (en) |
Families Citing this family (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8307422D0 (en) * | 1983-03-17 | 1983-04-27 | Rose L | Solubilising alginic material |
| US4960413A (en) * | 1985-11-09 | 1990-10-02 | The Shirley Institute | Wound dressing |
| JPS62141121A (en) * | 1985-12-07 | 1987-06-24 | Agency Of Ind Science & Technol | Production of binder yarn |
| GB8609367D0 (en) * | 1986-04-17 | 1986-05-21 | Johnson & Johnson | Adhesive wound dressing |
| US4793337A (en) * | 1986-11-17 | 1988-12-27 | E. R. Squibb & Sons, Inc. | Adhesive structure and products including same |
| US5254301A (en) * | 1988-03-29 | 1993-10-19 | Ferris Mfg. Corp. | Process for preparing a sheet of polymer-based foam |
| US5197945A (en) * | 1988-05-31 | 1993-03-30 | Minnesota Mining And Manufacturing Company | Alginate wound dressing of good integrity |
| ES2106722T3 (en) * | 1988-05-31 | 1997-11-16 | Minnesota Mining & Mfg | ALGINATE DRESSING FOR GOOD INTEGRITY WOUNDS. |
| JP2627344B2 (en) * | 1990-01-23 | 1997-07-02 | 工業技術院長 | Water-soluble algin fiber and method for producing the same |
| FR2671486B1 (en) * | 1991-01-16 | 1998-08-14 | Brother Laboratoires | COMPRESS FOR WOUND DRESSING. |
| DE4107239A1 (en) * | 1991-03-07 | 1992-09-10 | Hoechst Ag | TUBULAR FOOD COVER WITH IMPROVED REELABILITY |
| US5714232A (en) * | 1991-05-01 | 1998-02-03 | E. R. Squibb & Sons, Inc. | Alginate fabric, its use in wound dressings and surgical haemostats and a process for its manufacture |
| GB9109367D0 (en) * | 1991-05-01 | 1991-06-26 | Merck Sharp & Dohme | Surgical dressing |
| US5470576A (en) * | 1992-06-08 | 1995-11-28 | The Kendall Company | Process for preparing the alginate-containing wound dressing |
| US5840777A (en) * | 1992-06-19 | 1998-11-24 | Albany International Corp. | Method of producing polysaccharide foams |
| US5980930A (en) * | 1993-01-20 | 1999-11-09 | Bristol-Myers Squibb Company | Fibres |
| US5688923A (en) * | 1996-02-15 | 1997-11-18 | Hercules Incorporated | Pectin fibers |
| DE10007794A1 (en) * | 2000-02-21 | 2001-06-28 | Zimmer Ag | Composition useful for making containers, films, membranes and fibers, comprises a biodegradable polymer and a marine plant or shell material |
| NZ505514A (en) * | 2000-06-30 | 2003-02-28 | Bee & Herbal New Zealand Ltd | Method of manufacturing a wound dressing for the application of honey |
| GB0124530D0 (en) * | 2001-10-12 | 2001-12-05 | Acordis Speciality Fibres Ltd | Improved fabric |
| CN100457989C (en) * | 2006-11-04 | 2009-02-04 | 青岛大学 | Method for preparing high-strength alginic acid/gelatin cross-blend fiber and its use |
| CN100503912C (en) * | 2007-05-11 | 2009-06-24 | 青岛大学 | Preparation method of flame-proof algae fiber material |
| CN103170004B (en) * | 2012-04-23 | 2016-08-31 | 佛山市优特医疗科技有限公司 | A kind of method preparing contg. silver fiber wound dressing |
Family Cites Families (33)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA453829A (en) * | 1949-01-04 | James Hegan Horace | Manufacture of alginate threads | |
| US1225833A (en) * | 1911-12-14 | 1917-05-15 | Agnes Bennett Lilley | Paper absorbent material for surgical and sanitary purposes. |
| US1786781A (en) * | 1928-08-13 | 1930-12-30 | Burgess Lab Inc C F | Cloth-like fabric |
| US2371717A (en) * | 1940-06-12 | 1945-03-20 | Cefoil Ltd | Manufacture of spun textile fibers |
| US2375650A (en) * | 1942-01-20 | 1945-05-08 | Courtaulds Ltd | Manufacture and production of artificial filaments, threads, films, and the like |
| US2423075A (en) * | 1942-09-01 | 1947-06-24 | Courtaulds Ltd | Manufacture of alginate threads |
| GB567641A (en) * | 1942-09-01 | 1945-02-26 | Courtaulds Ltd | Improvements in and relating to the manufacture of alginate threads |
| GB571657A (en) * | 1942-09-01 | 1945-09-04 | Courtaulds Ltd | Improvements in and relating to the manufacture of alginate threads |
| GB568177A (en) * | 1943-02-19 | 1945-03-22 | Courtaulds Ltd | Improvements in and relating to the manufacture of threads, filaments, films and thelike from alginates |
| US2461094A (en) * | 1944-04-12 | 1949-02-08 | American Viscose Corp | Method of making lightweight filamentous structures |
| US2521738A (en) * | 1944-06-15 | 1950-09-12 | Thomas L Mcmeekin | Process for the production of artificial bristles and the like from proteins |
| GB624987A (en) * | 1947-07-22 | 1949-06-20 | Courtaulds Ltd | Improvements in and relating to the manufacture of alginate threads |
| GB653341A (en) * | 1948-04-27 | 1951-05-16 | Cyril Wilfred Bonniksen | An improved alginate medical or surgical preparation |
| GB674755A (en) * | 1949-08-04 | 1952-07-02 | Courtaulds Ltd | Improvements in and relating to the production of artificial protein fibres |
| US3063454A (en) * | 1959-02-26 | 1962-11-13 | Cleanese Corp Of America | Non-woven products |
| US3242120A (en) * | 1960-03-22 | 1966-03-22 | Du Pont | Self-supporting gel shaped structures |
| NL265218A (en) * | 1960-05-27 | |||
| US3802980A (en) * | 1962-03-19 | 1974-04-09 | C Harmon | Continuous filament web and method of manufacturing the same |
| US3545442A (en) * | 1964-09-23 | 1970-12-08 | Huyck Corp | Bandaging and dressing material |
| US3550592A (en) * | 1968-12-23 | 1970-12-29 | Kimberly Clark Co | Sanitary napkin and disposable wrapper therefor |
| US3824996A (en) * | 1969-11-18 | 1974-07-23 | R Carlisle | Highly absorbent pressure dressing for wounds |
| CA956423A (en) * | 1969-12-02 | 1974-10-22 | Asahi Kasei Kogyo Kabushiki Kaisha | High speed wet spinning technique |
| US3882063A (en) * | 1970-10-01 | 1975-05-06 | Shell Oil Co | Method of producing uniform fiberous webs by drawing partly fused particles |
| GB1375572A (en) * | 1971-08-12 | 1974-11-27 | ||
| GB1394741A (en) * | 1972-02-28 | 1975-05-21 | Medical Alginates Ltd | Calcium alginate conversion process |
| US3867935A (en) * | 1973-05-14 | 1975-02-25 | Johnson & Johnson | Plied absorbent structures |
| US4104115A (en) * | 1973-11-29 | 1978-08-01 | Carreras Rothmans, Limited | Method of making paper from water insoluble alginate fibers and the paper produced |
| US4016236A (en) * | 1974-05-15 | 1977-04-05 | Asahi Kasei Kogyo Kabushiki Kaisha | Process for manufacturing aromatic polymer fibers |
| JPS51130378A (en) * | 1975-05-08 | 1976-11-12 | Mitsubishi Rayon Co | Manufacture of sheettlike substance |
| JPS5246181A (en) * | 1975-10-08 | 1977-04-12 | Toyo Boseki | Manufacture of unwoven fabrics |
| US4051848A (en) * | 1976-03-01 | 1977-10-04 | Levine Norman S | Synthetic skin wound dressing |
| FR2418821A1 (en) * | 1978-03-03 | 1979-09-28 | Adeline Andre | Continuous mfr. of calcium alginate fibres - by passing calcium chloride and sodium alginate solns. through spinneret |
| IE49193B1 (en) * | 1979-04-18 | 1985-08-21 | Courtaulds Ltd | Process for making a non-woven alginate fabric useful as a wound dressing |
-
1982
- 1982-08-03 AU AU86710/82A patent/AU546556B2/en not_active Ceased
- 1982-08-05 DK DK351282A patent/DK351282A/en not_active Application Discontinuation
- 1982-08-12 IE IE1954/82A patent/IE53091B1/en unknown
- 1982-08-13 DE DE8282304280T patent/DE3279686D1/en not_active Expired
- 1982-08-13 EP EP19820304280 patent/EP0072680B1/en not_active Expired
- 1982-08-13 AT AT82304280T patent/ATE42974T1/en active
- 1982-08-13 JP JP57140922A patent/JPS5854059A/en active Granted
- 1982-08-17 CA CA000409567A patent/CA1192364A/en not_active Expired
- 1982-08-17 US US06/408,973 patent/US4562110A/en not_active Expired - Lifetime
- 1982-08-18 GR GR69056A patent/GR76271B/el unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DK351282A (en) | 1983-02-19 |
| GR76271B (en) | 1984-08-04 |
| AU546556B2 (en) | 1985-09-05 |
| JPS6151042B2 (en) | 1986-11-07 |
| EP0072680B1 (en) | 1989-05-10 |
| IE821954L (en) | 1983-02-18 |
| ATE42974T1 (en) | 1989-05-15 |
| JPS5854059A (en) | 1983-03-30 |
| US4562110A (en) | 1985-12-31 |
| DE3279686D1 (en) | 1989-06-15 |
| IE53091B1 (en) | 1988-06-08 |
| AU8671082A (en) | 1983-02-24 |
| EP0072680A3 (en) | 1983-03-09 |
| EP0072680A2 (en) | 1983-02-23 |
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