GB2203985A - Absorbent films - Google Patents

Absorbent films Download PDF

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Publication number
GB2203985A
GB2203985A GB08810227A GB8810227A GB2203985A GB 2203985 A GB2203985 A GB 2203985A GB 08810227 A GB08810227 A GB 08810227A GB 8810227 A GB8810227 A GB 8810227A GB 2203985 A GB2203985 A GB 2203985A
Authority
GB
United Kingdom
Prior art keywords
water
film
absorbent
polymer
particles
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.)
Granted
Application number
GB08810227A
Other versions
GB8810227D0 (en
GB2203985B (en
Inventor
Robert Saunders Taylor
John Frederick Carefull
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Akzo Nobel UK PLC
Original Assignee
Courtaulds PLC
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Courtaulds PLC filed Critical Courtaulds PLC
Publication of GB8810227D0 publication Critical patent/GB8810227D0/en
Publication of GB2203985A publication Critical patent/GB2203985A/en
Application granted granted Critical
Publication of GB2203985B publication Critical patent/GB2203985B/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/58—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising fillers only, e.g. particles, powder, beads, flakes, spheres
    • B29C70/64—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising fillers only, e.g. particles, powder, beads, flakes, spheres the filler influencing the surface characteristics of the material, e.g. by concentrating near the surface or by incorporating in the surface by force
    • 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
    • A61L15/26—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof
    • 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
    • A61L15/42—Use of materials characterised by their function or physical properties
    • A61L15/60—Liquid-swellable gel-forming materials, e.g. super-absorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0037—Other properties
    • B29K2995/0068—Permeability to liquids; Adsorption
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2007/00—Flat articles, e.g. films or sheets
    • B29L2007/008—Wide strips, e.g. films, webs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/48—Wearing apparel
    • B29L2031/4871—Underwear
    • B29L2031/4878—Diapers, napkins

Abstract

A water-absorbent film comprises particles of water-absorbent material at least partially embedded in the surface of a film of a less water-absorbent polymer. The water-absorbent particles are preferably capable of absorbing at least twenty times their own weight of water and can for example be a salt of a lightly crosslinked carboxylic acid-functional polymer. The film can be used for absorbing aqueous fluids, for example in diapers, incontinence garments, sanitary napkins, bandages and wiping cloths. The film may be prepared by applying the particles to the surface of a film while it is in a liquid or plastic condition.

Description

Absorbent Films This invention relates to films for absorbing aqueous fluids, for example in diapers and incontinence garments, sanitary napkins, bandages and wiping cloths.
The use of water-absorbent fibrous materials, for example in the form of woven or non-woven fabric or layers of pulp, is known in such products. It has also been suggested to use particles of highly water-absorbent material such as a polyacrylate salt in diapers and incontinence garments. Such a highly water-absorbent material can absorb many times its weight of water to form a gel. When used in a diaper, however, the powder or the gel formed when it is soaked may become dislodged so that it forms large3 lumps of gelatinous material and/or is partly outside the diaper. The gel may adhere to the user; this is unsightly and uncomfortable.
A water-absorbent film according to the invention comprises particles o water-absorbent material at least partially embedded in a major surface of a film of a less water-absorbent polymer.
The water-absorbent material can for example be a salt of a lightly crosslinked, carboxylic-acid-functional polymer, for example a sodium salt of polyacrylic acid or polymethacrylic acid or a copolymer containing a major proportion (at least 50 per cent by weight) of acrylic acid or methacrylic acid. The acid - functional polymer preferably consists of high molecular weight polymer chains with a few crossl inks, for example a copolymer of- acrylic or methacrylic acid with less than 0.1 per cent by weight, for example 0.03 per cent, of a monomer having two polymerisable unsaturated bonds, such as divinylbenzene or ethylene glycol dimethacrylate. The polymer preferably contains at least 90 per cent by weight acid-functional monomer units and most preferably consists wholly of such units apart from the crosslinking monomer.The waterabsorbent material can alternatively be a lightly crosslinked polyacrylamide or a crosslinked polysaccharide which is water - soluble or - dispersible in its noncrosslinked state or a polysaccharide grafted with a hydrophilic material, for example polyacrylic acid grafted onto starch. The water-absorbent material is preferably capable of absorbing at least 20 times its own weight of water.
The average particle size of the water-absorbent material is preferably 0.1 to 2 millimetres. Within this range smaller particles absorb aqueous fluids more rapidly but larger particles allow greater overall absorptive capacity. A mixture of particle sizes may be preferred.
The polymer from which the film is formed is preferably a thermoplastic polymer and can be selected from a wide range of polymer types, for example a polyolefin such as polyethylene or polypropylene, a vinyl polymer such as polyvinyl chloride or a vinyl acetate polymer, an acrylic polymer such as a homopolymer or copolymer of one or more acrylate or methacrylate esters, optionally with styrene or acrylonitrile, a polyester, a polyurethane, a polyamide or cellulose acetate.
A process according to the invention for forming a water-absorbent film comprises applying particles of a water-absorbent material to a major surface of a film of a less water-absorbent polymer while the film is in a liquid or plastic condition so that the particles become at least partially embedded in the surface of the film.
The polymer film can for example be formed by melt extrusion or by casting from solution. The particles of absorbent material are preferably applied to the film while it is still in a liquid or plastic condition during its manufacture, although the particles -can alternatively be applied to a heat-softened pre'formed thermoplastic film.
In one preferred process a thermoplastic polymer is melt-extruded to form a film and is cooled, for example by forced air cooling. The particles of absorbent material are applied to the film during the cooling process while the film is still tacky. The particles can be applied from a spreading and metering device or can be applied from a hopper and then passed under a spreader blade.
The particles of absorbent material are preferably applied so that they cover at least 50 per cent of the area of film being treated. They can for example be applied in excess, with recovery and re-use of particles which have not adhered to the film.
The degree of penetration of the film by the particles can vary according to the softness of the film at the point at which the particles are applied, for example the temperature of the film at that point in the case of melt extruded films. Particles can be applied to one or both sides of the film. The film can be subjected to pressure after the particles have been applied to the film to embed the particles more firmly in the film, if desired. The particles may penetrate through the film so that the water is transported through the film by the absorbent particles.
Alternatively, the absorbent particles may be partially embedded in one surface of the film, with the other surface being a substantially unbroken surface of the less waterabsorbent polymer so that water is not easily passed through the film.
Alternatively, the film can be produced by casting a solution of the less water-absorbent polymer in an organic solvent on to a support, drying the film so cast and stripping it from the support. The particles of absorbent material are applied as the film is drying on the support.
Some types of absorbent material may absorb certain types of organic solvent, particularly polar organic solvents, and may give rise to longer drying times and even some weakening of the film.
The water-absorbent film of the invention can be used in a diaper or incontinence garment as the only absorbent or in conjunction with other absorbent materials. For example a diaper may consist of a water-permeable cover sheet to - contact the user, a layer of conventional fibrous absorbent material such as fluffed pulp to soak the liquid away from the cover sheet, and an absorbent film behind the fluffed pulp to provide the major water-retaining capacity of the diaper. The absorbent film can be used as a layer over the whole area of the diaper or in spaced strips; strips are preferred if the film is coated with particles of absorbent material on both surfaces. A water-impermeable backing sheet is preferably used behind the film in any case. The water-absorbent film can alternatively be used as a cloth for wiping up spilt aqueous fluid.
The invention is illustrated by the following Example: Example A copolymer of acrylonitrile, methyl acrylate and vinyl acetate in weight ratio 71:18:11 was dissolved in dimethyl formamide at 40 per cent by weight. A film was cast by spreading the solution on a glass plate and allowing it to dry under ambient conditions (about 25or).
After one minute a sodium polyacrylate polymer powder (particles passing an 0.5 mm sieve when dry) was sprinkled on to the surface of the film. When dry the resulting film with embedded sodium polyacrylate particles was peeled from the plate. The thickness of the film was 0.05 millimetres and the proportion of sodium polyacrylate particles substantially covered the surface of the film.
Water was applied to the film at the surface having the embedded sodium polyacrylate particles. The film was observed to pick up water by absorption by and consequent swelling of the embedded particles. Water was also transported through the film.

Claims (22)

1. A water-absorbent film comprising particles of water-absorbent material at least partially embedded in a major surface of a film of a less water-absorbent polymer.
2. A water-absorbent film according to claim 1 in which the water-absorbent material is capable of absorbing at least twenty times its own weight of water.
3. A water-absorbent film according to claim 1 or claim 2 in which the average particle size of the waterabsorbent material is in the range 0.1 - 2 mm.
4. A water-absorbent film according to any of claims 1 to 3 in which the particles of water-absorbent material penetrate through the film.
5. A water-absorbent film according to any of claims 1 to 3 in which the particles of water-absorbent material are partially embedded in one major surface of the film and in which the other major surface of the film has a substantially unbroken surface of the less water-absorbent polymer.
6. A water-absorbent film according to any of claims 1 to 5 in which the water-absorbent material is a salt of a lightly crosslinked, carboxylic acid-functional polymer.
7. A water-absorbent film according to claim 6 in which the acid-functional polymer is a polymer containing at least 50% by weight acrylic acid or methacrylic acid units.
8. A water-absorbent film according to claim 7 in which the acid-functional polymer contains at least 90% by weight acrylic acid or methacrylic acid units.
9. A water-absorbent film according to any of claims 1 to 5 in which the water-absorbent material is a lightly -crosslinked polyacrylamide.
10. A water-absorbent film according to any of claims 1 to 5 in which the water-absorbent material is a crosslinked polysaccharide which is water-soluble or waterdispersible in its non-crosslinked state.
11. A water-absorbent film according to any of claims 1 to 5 in which the water-absorbent material is a polysaccharide grafted with a hydrophilic material.
12. A water-absorbent film according to any of claims 1 to 11 in which the less water-absorbent polymer is a thermoplastic polymer.
13. A water-absorbent film according to claim 12 in which the thermoplastic polymer is a polyolefin, a vinyl polymer, an acrylic polymer, a polyester, a polyurethane, a polyamide or cellulose acetate.
14. A process #for forming a water-absorbent film comprising applying particles of a water-absorbent material to a major surface of a film of a less water-absorbent polymer while the film is in a liquid or plastic condition so that the particles become at least partially embedded in the surface of the film.
15. A process according to claim 14 in which the less water-absorbent polymer is a thermoplastic polymer which is melt-extruded to form a film and in which the particles of water-absorbent material are applied to the film while the film is still tacky during cooling of the film.
16. A process according to claim 14 in which the less water-absorbent polymer is a thermoplastic polymer and the particles of water-absorbent material are applied to a heat-softened thermoplastic film.
17. A process according to claim 14 in which a film is produced by casting a solution of the less waterabsorbent polymer in an organic solvent onto a support, drying the film so cast and applying the particles of water-absorbent material as the film is drying on the support.
18. A process according to any of claims 14 to 17 in which the film is subjected to pressure after the particles have been applied to the film to embed the particles more firmly in the film.
19. A process for the preparation of a waterabsorbent film carried out substantially as described in the foregoing Example.
20. A water-absorbent film when produced by a process according to any of claims 14 to 19.
21. A diaper or incontinence garment containing a water-absorbent film as claimed in any of claims 1 to 13 or 20.
22. A diaper according to claim 21 comprising a water-permeable cover sheet to contact the user, a layer of fibrous absorbent material to soak liquid away from the cover sheet, a water-absorbent film according to any of claims 1 to 13 or 20 positioned behind the fibrous absorbent material, and a water-impermeable backing sheet.
GB8810227A 1987-04-30 1988-04-29 Absorbent films Expired - Lifetime GB2203985B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB878710328A GB8710328D0 (en) 1987-04-30 1987-04-30 Absorbent films

Publications (3)

Publication Number Publication Date
GB8810227D0 GB8810227D0 (en) 1988-06-02
GB2203985A true GB2203985A (en) 1988-11-02
GB2203985B GB2203985B (en) 1990-03-07

Family

ID=10616672

Family Applications (2)

Application Number Title Priority Date Filing Date
GB878710328A Pending GB8710328D0 (en) 1987-04-30 1987-04-30 Absorbent films
GB8810227A Expired - Lifetime GB2203985B (en) 1987-04-30 1988-04-29 Absorbent films

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB878710328A Pending GB8710328D0 (en) 1987-04-30 1987-04-30 Absorbent films

Country Status (1)

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GB (2) GB8710328D0 (en)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2268687A (en) * 1992-07-17 1994-01-19 Janet Alice Israel Absorbent breast pad
EP0602617A2 (en) * 1992-12-18 1994-06-22 Hoechst Celanese Corporation Superabsorbent structure
EP0614671A1 (en) * 1993-03-09 1994-09-14 Hoechst Celanese Corporation Method for immobilizing superabsorbent polymers
GB2282155A (en) * 1993-09-22 1995-03-29 Moelnlycke Ab A superabsorbent fibre or nonwoven material
WO1999004739A1 (en) * 1997-07-25 1999-02-04 The Procter & Gamble Company Absorbent articles having a liquid swellable material coated breathable backsheet
US6436508B1 (en) 1997-07-25 2002-08-20 The Procter & Gamble Company Absorbent articles having a liquid swellable material coated breathable backsheet
EP1319414A1 (en) * 2001-12-11 2003-06-18 The Procter & Gamble Company Liquid absorbing thermoplastic materials and the utilization thereof in absorbent articles
WO2004096301A2 (en) * 2003-04-24 2004-11-11 Dow Global Technologies Inc. Fluid-absorbent compositions and articles, porous articles, and methods for making the same

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1161755A (en) * 1965-06-29 1969-08-20 Bofors Tidaholmsverken Aktiebo Method of Producing Plastics Layers containing Filler
EP0049944A1 (en) * 1980-08-25 1982-04-21 Johnson & Johnson Absorbent products, process and compositions for immobilization of particulate absorbents
EP0096976A2 (en) * 1982-05-21 1983-12-28 Weyerhaeuser Company Absorbent panel suitable for use in absorbent products and process for its production
GB2156370A (en) * 1984-03-27 1985-10-09 Personal Products Co Dispersed absorbent products and method of use

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1161755A (en) * 1965-06-29 1969-08-20 Bofors Tidaholmsverken Aktiebo Method of Producing Plastics Layers containing Filler
EP0049944A1 (en) * 1980-08-25 1982-04-21 Johnson & Johnson Absorbent products, process and compositions for immobilization of particulate absorbents
EP0096976A2 (en) * 1982-05-21 1983-12-28 Weyerhaeuser Company Absorbent panel suitable for use in absorbent products and process for its production
GB2156370A (en) * 1984-03-27 1985-10-09 Personal Products Co Dispersed absorbent products and method of use

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2268687A (en) * 1992-07-17 1994-01-19 Janet Alice Israel Absorbent breast pad
EP0602617A2 (en) * 1992-12-18 1994-06-22 Hoechst Celanese Corporation Superabsorbent structure
EP0602617A3 (en) * 1992-12-18 1994-06-29 Hoechst Celanese Corporation Superabsorbent structure
US5433994A (en) * 1992-12-18 1995-07-18 Mckinney; Betty J. Superabsorbent structure
EP0614671A1 (en) * 1993-03-09 1994-09-14 Hoechst Celanese Corporation Method for immobilizing superabsorbent polymers
TR27863A (en) * 1993-03-09 1995-10-11 Hoechst Celanese Corp Method for immobilizing superabsorbent polymers.
US6194630B1 (en) 1993-09-22 2001-02-27 Sca Hygiene Products Aktiebolag Superabsorbent fibre or nonwoven material, a method for its manufacture, and an absorbent article comprising the superabsorbent fibre or nonwoven material
GB2282155A (en) * 1993-09-22 1995-03-29 Moelnlycke Ab A superabsorbent fibre or nonwoven material
GB2282155B (en) * 1993-09-22 1997-06-04 Moelnlycke Ab A superabsorbent fibre, a method for its manufacture, and an absorbent article comprising the superabsorbent fibre
WO1999004739A1 (en) * 1997-07-25 1999-02-04 The Procter & Gamble Company Absorbent articles having a liquid swellable material coated breathable backsheet
EP0897705A1 (en) * 1997-07-25 1999-02-24 The Procter & Gamble Company Absorbent articles having a liquid swellable material coated breathable backsheet
US6436508B1 (en) 1997-07-25 2002-08-20 The Procter & Gamble Company Absorbent articles having a liquid swellable material coated breathable backsheet
EP1319414A1 (en) * 2001-12-11 2003-06-18 The Procter & Gamble Company Liquid absorbing thermoplastic materials and the utilization thereof in absorbent articles
WO2003049777A1 (en) * 2001-12-11 2003-06-19 The Procter & Gamble Company Liquid absorbing thermoplastic materials and the utilization thereof in absorbent articles
WO2004096301A2 (en) * 2003-04-24 2004-11-11 Dow Global Technologies Inc. Fluid-absorbent compositions and articles, porous articles, and methods for making the same
WO2004096301A3 (en) * 2003-04-24 2005-01-27 Dow Global Technologies Inc Fluid-absorbent compositions and articles, porous articles, and methods for making the same

Also Published As

Publication number Publication date
GB8810227D0 (en) 1988-06-02
GB2203985B (en) 1990-03-07
GB8710328D0 (en) 1987-06-03

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