GB1596823A

GB1596823A - Shaped structure and a process for its manufacture

Info

Publication number: GB1596823A
Application number: GB6599/78A
Authority: GB
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1977-02-21
Filing date: 1978-02-20
Publication date: 1981-09-03
Also published as: NO780581L; NL7801849A; SE7801852L; FR2380770B1; FR2380770A1; DE2707392C3; DE2707392B2; DE2707392A1

Description

(54) SHAPED STRUCTURE AND A PROCESS FOR ITS MANUFACTURE (71) We, HOECHST AKTIENGESELLSCHAFT, a Body Corporate organised according to the laws of the Federal Republic of Germany, of 6230 Frankfurt/Main 80, Postfach 80 03 20, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a shaped structure, suitable for use as a dressing material, and a process for its manufacture.

Gauze and cotton wool are generally used as the material for wet dressings in combating inflammation and for heat therapy. The term "dressing material" is to be understood as including material suitable for wraps, packs, compresses, bandages and the like. For this purpose, the gauze bandage or cotton wool, soaked with a liquid, for example water, alcohol, or a boric acid or other aqueous solution exerting a healing action, is placed on the part of the body of the patient which is to be treated and, if necessary, covered with, for example, a watertight film.

DE-OS 2,448,930 discloses a bandaging material of hydrophobic soft plastic foam, one entire surface of which is laminated to a plastic film. Because of its water-repellency, this bandaging material is unsuitable as a sorbent dressing material. The same applies to the wound dressings known from DE-OS 2,103,590 and DE-AS 1,247,553.

The present invention is concerned with providing a hydrophilic dressing material which has a good adsorbent power and, at the same time, a good padding effect, and is suitable for wet dressings without the need for additional subsequent covering with a water-tight film.

The present invention provides a shaped structure, suitable for use as a dressing material, which comprises a layer of porous regenerated cellulose containing at least 3% by weight, based on the total weight of the porous layer, of a finely divided weldable or sealable thermoplastic filler, the layer of porous regenerated cellulose being bonded by welding or sealing to a thermoplastic film along a weldable or sealable surface of the film.

Advantageously, the thermoplastic filler in finely divided form is in the form of powder, fibers, fibrids, or a mixture of two or more such forms of subdivision.

The present invention also provides a process for the manufacture of the shaped structure, which comprises incorporating at least one finely divided weldable or sealable thermoplastic filler into a viscose mixture, forming a layer of porous regenerated cellulose from the viscose, and bonding the layer of porous regenerated cellulose to a thermoplastic film along a weldable or sealable surface of the film by welding or sealing. As used herein, the term "weldable or sealable" thermoplastic is used to refer to any of the large number of thermoplastics, which are well known to those skilled in the art, which are capable of being heat-bonded to another polymer and/or material.As also used herein, the terms "welding" or "sealing" refer to any of those methods a large number of which are well known to those skilled in the art, by which a weldable or sealable thermoplastic may be heat-bonded to another thermoplastic and/or different material.

The layer of porous regenerated cellulose may be provided from viscose in any desired manner, many of which are known per se.

Layers of porous regenerated cellulose are especially layers having a sponge-like structure, for example sponge cloth or other sponges. The layer is given its shape by known procedures, for example by pressing, and/or cutting to length, a web of sponge cloth material. Depending on its intended use, it may have a sheet-like shape or it may be adapted to the parts of the body which are to be covered, for example in the form of a finger stall, and the term "layer" is accordingly to be construed without limitation to any particular shape or dimension.

To manufacture the layer of porous regenerated cellulose, pulp is first converted into viscose, as is known. If desired, rein forcing fibers, for example cotton fibers of a length of 12 to 15 mm, and, for forming the pores, grains of a salt, in particular crystals of Glauber's salt, of the desired particle size are incorporated into the viscose. The composition is then applied, for example, to an endless carrier belt and, while hot, coagulated by the coagulation medium, for example by a water bath at about 100 C. In the water bath, a large part of the salt is dissolved and washed out. The porous shaped article then runs through a precipitating bath containing aqueous sulfuric acid, if appropriate a chlorite bleach bath and a further wash bath, where the porous shaped article is intensively washed with water.

Finally, the water which has been absorbed is squeezed out and the article is dried.

The plastic film is bonded by sealing or welding to one surface of the porous regenerated cellulose layer. As indicated above, it is a prerequisite for this that on the one hand the surface of the porous layer consisting of regenerated cellulose is sealable or weldable and, on the other hand, at least that surface of the plastic film which faces the surface of the porous layer consists of a weldable or sealable material. Advantageously the weldable or sealable filler in the porous layer is the same material as that of the weldable or sealable surface of the film.

Suitable weldable or sealable thermoplastics, are, for example, polyolefines, polyamides, polyvinyl chloride, polystyrene, and mixtures of any two or more such materials.

The plastic powder or the fibers and/or fibrids are preferably incorporated into the viscose during the manufacture of the porous shaped article, for example by kneading or stirring, a minimum amount of at least 3 per cent by weight, relative to the porous shaped particle, being necessary. Subsequently, the viscose is coagulated in the customary manner. The addition of more than 40 per cent by weight of plastic filler material is not necessary and, moreover, leads to a gradual deterioration of the strength of the porous shaped article. The particles if in a powder form preferably have a size from one micron up to 2 mm, preferably 0.5-lmm, if in fiber form have an average length from 4 to 30 mm, preferably 10 to 15 mm, and if in fibrid form 0.05 to 15 mm preferably 1 to 3 mm.Fibrids are preferably the compounds known as "synthetic wood pulp", the manufacture of which is described, for example, in DE-OS 2,249,604 or 2,411,589.

In the case of a single-layer film, the plastic film advantageously consists, for example, of a homopolymer or copolymer of an olefine, e.g., ethylene and propylene, a polyamide, polyvinyl chloride or polystyrene. If the film is a two-layer film, a laminate of, for example, polyethylene/polyamide, polyethylene/polyester or polyamide/polyvinyl chloride may be employed. The film may be a three-layer laminate; preferably it then contains one of the above mentioned single-layer films as a weldable or sealable layer and with, for example, an aluminium foil as an interlayer and a film of regenerated cellulose, polypropylene or polyester forming the lamina remote from the porous regenerated cellulose layer.

The welding or sealing of the plastic film to the surface of the porous shaped article is effected bv any desired device, many of which are known and used, for example, in the manufacture of laminated films.

The surface of the porous layer, which is to come into direct contact with the part of the body of the patient, is not covered by the plastic film, so the material according to the invention can be employed as a wet bandage.

When used for wet dressings, the porous part of the material according to the invention is wetted and brought into contact with the part of the body of the patient which is to be treated; the plastic film which is sealed or welded on over the entire surface of the porous layer ensures that adjacent clothing, bedding and the like do not become wet. A further advantage is that the absorbed liquid can act over a prolonged period since evaporation is inhibited.

In order to prevent the emergence of moisture even at the edges of the dressing material, the area of the film is preferably larger than the surface of the porous layer which it covers.

If, however, bandages are to be applied, from which it is intended that the absorbed liquid is gradually evaported by the body heat of the patient, the film of the dressing material may be microporous and/or perforated, that is to say provided with small pores which are introduced into the film, for example, mechanically or by chemical means in a known manner. Microporous films are known; they normally have a leathery handle or feel. To fasten the dressing material, it may be provided, as appropriate, with one or more closures, for example with a clinging closure, selfadhesive tapes, tying straps and the like.

The attached Figure illustrates one form of bandage constructed in accordance with the invention. Reference numeral 1 designates a plastic film, 2 designates a sponge cloth bonded by welding or sealing and 3 designates a clinging closure. The relative thickness of the film has been exaggerated for clarity.

WHAT WE CLAIM IS: 1. A shaped structure, suitable for use

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. forcing fibers, for example cotton fibers of a length of 12 to 15 mm, and, for forming the pores, grains of a salt, in particular crystals of Glauber's salt, of the desired particle size are incorporated into the viscose. The composition is then applied, for example, to an endless carrier belt and, while hot, coagulated by the coagulation medium, for example by a water bath at about 100 C. In the water bath, a large part of the salt is dissolved and washed out. The porous shaped article then runs through a precipitating bath containing aqueous sulfuric acid, if appropriate a chlorite bleach bath and a further wash bath, where the porous shaped article is intensively washed with water. Finally, the water which has been absorbed is squeezed out and the article is dried. The plastic film is bonded by sealing or welding to one surface of the porous regenerated cellulose layer. As indicated above, it is a prerequisite for this that on the one hand the surface of the porous layer consisting of regenerated cellulose is sealable or weldable and, on the other hand, at least that surface of the plastic film which faces the surface of the porous layer consists of a weldable or sealable material. Advantageously the weldable or sealable filler in the porous layer is the same material as that of the weldable or sealable surface of the film. Suitable weldable or sealable thermoplastics, are, for example, polyolefines, polyamides, polyvinyl chloride, polystyrene, and mixtures of any two or more such materials. The plastic powder or the fibers and/or fibrids are preferably incorporated into the viscose during the manufacture of the porous shaped article, for example by kneading or stirring, a minimum amount of at least 3 per cent by weight, relative to the porous shaped particle, being necessary. Subsequently, the viscose is coagulated in the customary manner. The addition of more than 40 per cent by weight of plastic filler material is not necessary and, moreover, leads to a gradual deterioration of the strength of the porous shaped article. The particles if in a powder form preferably have a size from one micron up to 2 mm, preferably 0.5-lmm, if in fiber form have an average length from 4 to 30 mm, preferably 10 to 15 mm, and if in fibrid form 0.05 to 15 mm preferably 1 to 3 mm.Fibrids are preferably the compounds known as "synthetic wood pulp", the manufacture of which is described, for example, in DE-OS 2,249,604 or 2,411,589. In the case of a single-layer film, the plastic film advantageously consists, for example, of a homopolymer or copolymer of an olefine, e.g., ethylene and propylene, a polyamide, polyvinyl chloride or polystyrene. If the film is a two-layer film, a laminate of, for example, polyethylene/polyamide, polyethylene/polyester or polyamide/polyvinyl chloride may be employed. The film may be a three-layer laminate; preferably it then contains one of the above mentioned single-layer films as a weldable or sealable layer and with, for example, an aluminium foil as an interlayer and a film of regenerated cellulose, polypropylene or polyester forming the lamina remote from the porous regenerated cellulose layer. The welding or sealing of the plastic film to the surface of the porous shaped article is effected bv any desired device, many of which are known and used, for example, in the manufacture of laminated films. The surface of the porous layer, which is to come into direct contact with the part of the body of the patient, is not covered by the plastic film, so the material according to the invention can be employed as a wet bandage. When used for wet dressings, the porous part of the material according to the invention is wetted and brought into contact with the part of the body of the patient which is to be treated; the plastic film which is sealed or welded on over the entire surface of the porous layer ensures that adjacent clothing, bedding and the like do not become wet. A further advantage is that the absorbed liquid can act over a prolonged period since evaporation is inhibited. In order to prevent the emergence of moisture even at the edges of the dressing material, the area of the film is preferably larger than the surface of the porous layer which it covers. If, however, bandages are to be applied, from which it is intended that the absorbed liquid is gradually evaported by the body heat of the patient, the film of the dressing material may be microporous and/or perforated, that is to say provided with small pores which are introduced into the film, for example, mechanically or by chemical means in a known manner. Microporous films are known; they normally have a leathery handle or feel. To fasten the dressing material, it may be provided, as appropriate, with one or more closures, for example with a clinging closure, selfadhesive tapes, tying straps and the like. The attached Figure illustrates one form of bandage constructed in accordance with the invention. Reference numeral 1 designates a plastic film, 2 designates a sponge cloth bonded by welding or sealing and 3 designates a clinging closure. The relative thickness of the film has been exaggerated for clarity. WHAT WE CLAIM IS:

1. A shaped structure, suitable for use

as a dressing material, which comprises a layer of porous regenerated cellulose containing at least 3% by weight, based on the total weight of the porous layer, of a finely divided weldable or sealable thermoplastic filler. the layer of porous regenerated cellulose being bonded by welding or sealing to a thermoplastic film along a weldable or sealable surface of the film.

2. A structure as claimed in claim 1, wherein the finely divided filler is in the form of powder, fibers, fibrids, or a mixture of two or more such forms.

3. A structure as claimed in claim 1 or claim 2, wherein the plastic film is bonded to only one entire surface of the porous layer.

4. A structure as claimed in claim 3, wherein the film extends over an area greater than that of the surface of the porous layer to which it is bonded.

5. A structure as claimed in any one of claims 1 to 4, wherein the film is perforated.

6. A structure as claimed in any one of claims 1 to 5, wherein the film is a single layer film.

7. A structure as claimed in any one of claims 1 to 5, wherein the film is a two-layer film.

8. A structure as claimed in any one of claims 1 to 5, wherein the film is a threelayer film.

9. A structure as claimed in any one of claims 1 to 8, wherein at least the film whose surface is bonded to the layer of porous regenerated cellulose is an olefine polymer, a polyamide, polyvinyl chloride, or polystyrene.

10. A structure as claimed in any one of claims 1 to 9, wherein the weldable or sealable filler in the porous layer is the same material as that of the weldable or sealable surface of the film.

11. A dressing, comprising an article as claimed in any one of claims 1 to 10.

12. A dressing, substantially as hereinbefore described with reference to the accompanying drawing.

13. A process for the manufacture of a shaped structure as claimed in claim 1, which comprises incorporating a finely divided weldable or sealable thermoplastic filler into a viscose mixture, forming a layer of porous regenerated cellulose from the viscose, and bonding the layer of porous regenerated cellulose to the thermoplastic film along a weldable or sealable surface of the film by welding or sealing.

14. A process as claimed in claim 13, carried out substantially as hereinbefore described.