IE49972B1

IE49972B1 - Sanitary towels and other absorbent elements

Info

Publication number: IE49972B1
Application number: IE1673/80A
Authority: IE
Original assignee: Oreal
Priority date: 1979-08-10
Filing date: 1980-08-08
Publication date: 1986-01-22
Also published as: FR2462902A1; BE884699A; IT8068276A0; GB2055586B; DE3030096A1; IE801673L; GB2055586A; IT1129240B; NL8004404A; ES260303U; DK342280A; FR2462902B1

Abstract

A sanitary towel, baby nappy, bandage or other absorbent element comprises an absorbent material (9, 10) enclosed within an envelope including a layer of non-woven material (6) to contact the skin of the user. A layer (11) of a flexible material which has been expanded in a manner analogous to "expanded metal" by slitting and stretching perpendicular to the direction of the parallel lines of slits is included in the envelope with the absorbent material either as a flexible reinforcement or to facilitate passage of body liquids from the non-woven material (6) to the absorbent material (9, 10).

Description

The present invention relates to absorbent elements or products, such as sanitary towels for feminine hygiene, baby nappies, draw-sheets for incontinent patients or adhesive bandages.

It is known to produce sheets of metal gauze, known under the name Expanded metal, from a sheet of metal. To obtain an expanded structure of this type, the sheet constituting the starting material is cut along parallel lines in which the cut zones are separated from one another by narrow uncut zones, the cut zones in one line having a staggered arrangement relative to the cut zones in the two adjacent lines, and the metal which has been pre-cut in this way is subjected to traction, making it possible to form meshes at right angles to each cut zone.

It has already been proposed to apply the same technique using flexible plastics sheet instead of the metal sheets; in this case, the cutting is carried out in the same manner as for the metal sheets, but the traction perpendicular to the cutting lines, which enables the meshes to be formed, must be followed by a fixing stage because of the flexibility of the plastics sheet. This fixing stage is carried out either by means of a heat treatment or by coating with a binder, for example by spraying, and drying the said binder on the stretched material. In all cases, the material obtained constitutes a sheet which has a relatively large transverse thickness because of the deformation imparted to each strip of the plastics sheet, delimited between two successive cutting lines. Because of the staggered arrangement of the cut zones in two successive cutting lines, each strip is linked to the two parallel adjacent strips by points which are staggered along its edges, and, vdien the traction is exerted in order to expand the pre-cut plastics sheet, this staggered arrangement of the links of the strip causes undulaticn of the said strip on either side of the plane of the initial pre-cut sheet. This undulation creates an expanded structure, the transverse thickness of which is a function of the expanding traction applied to the pre-cut material and of the width of the initial strips, this thickness being between the thickness of the initial plastics sheet and twice the distance existing between the two successive parallel cutting lines, that is to say twice the width of the strips subjected to undulation at the moment of expansion.

It has been found that it is thus possible to obtain flexible expanded plastics sheets which are very light and have a relatively large transverse thickness. These sheets remain flexible, despite the appearance of the meshes after expansion of the material, and they possess a large number of meshes which constitute small cells uniformly distributed over the whole surface of the sheet. The same expansion technique can of course be used for all flexible sheets, for example sheets made of a rubbery material, ordinary, creped or wadded paper, or a non-woven product manufactured by dry or wet processing. It can also be envisaged to expand sheets consisting of complex materials, for example sheets of plastics and of cellulose wadding, the expansion of the pre-cut material creating an imbrication of the two layers of the complex material, which promotes the integration of these two layers with one another.

The object of the invention is to propose an improvement in the production of absorbent elements or products, such as, for example, sanitary towels for feminine hygiene, baby nappies, draw-sheets for incontinent patients or adhesive bandages. All these elements or products have an approximately flat shape and contain an absorbent mass. This absorbent mass can have various · constitutions, but in all cases, its function is to absorb the physiological liquids and to retain them inside the element. An absorbent element of this type is enveloped in an external sheet, for example made of a non-woven product, this sheet generally coming into contact with the skin or the mucous membranes of the user. For reasons of comfort, it is important for the external sheet, which constitutes the external envelope of the absorbent element, to remain as dry as possible. It is therefore desirable for this sheet to be separated from the absorbent mass by a material which, on the one hand, allows the physiological liquids to pass through towards the absorbent core, and, on the other hand, maintains a space between the external envelope and the absorbent mass.

The present invention proposes to use, for this purpose, a sheet of flexible material of expanded structure, it being possible for this sheet to be formed by the prior cutting and the expansion of a sheet of plastics, a sheet of rubbery material, a sheet of paper, a sheet of nonwoven or a sheet of sandwich material, or of any other similar sheets. The material producing the sheet of expanded structure must simply be a flexible material so that the sheet of expanded structure retains sufficient flexibility to ensure the comfort experienced by the user of the absorbent element produced.

According to the present invention there is provided an absorbent element, in particular a sanitary towel, baby nappy, draw-sheet or bandage, which comprises an envelope at least part of which consists of a layer intended to come into contact with the mucous membranes, the dermis or the epidermis of a user, of the absorbent element and, within the envelope, an absorbent mass capable .49872 of absorbing and retaining a liquid,at least one sheet of a flexible material of expanded structure being included inside the envelope.

In a preferred embodiment, the sheet of flexible 5 material of expanded structure is obtained from a sheet of plastics material, paper, nonwoven material, elastic material or complex or sandwich material, by cutting to form parallel and staggered cuts, then expanding under a traction perpendicular to the abovementioned cuts, and finally fixing the expanded structure produced in this way; the expanded structure is fixed by subjecting the sheet, after the traction stage, either to the action of heat or to coating with binders, followed by drying.

If the sheet converted to an expanded structure is a plastics sheet, it can advantageously consist of polyethylene, polypropylene, polyester or polyamide. If the sheet converted to an expanded structure is a sheet of paper, it can be a sheet of ordinary paper or of creped paper or wadded paper, or also of paper impregnated, for exanple, by means of a plastics. If the expanded structure is obtained from a sheet of complex material, it can advantageously consist of a hydrophobic layer and a hydrophilic layer; the hydrophobic layer can be made of plastics, whilst the hydrophilic layer is made of cellulose wadding.

Amongst the expanded complexes comprising a 4997» hydrophilic face and a hydrophobic face, the example of the expanded complex produced from a flocked plastics should be mentioned, the flocking being carried out in accordance with the conventional techniques, and the fibre used then being a hydrophilic fibre of the wood pulp, viscose or cotton type or the like.

In a first variant, the absorbent element according to the invention comprises at least one sheet of expanded structure, which is arranged between the layer of the external envelope and the absorbent mass.

In another variant, the absorbent element according to the invention comprises at least one sheet of expanded structure, which is arranged inside the absorbent mass. In this case, according to a first embodiment, the sheet of expanded structure can be dusted with a retention material chosen from the group comprising carboxymethylcelluloses, polyacrylonitrile/starch graft copolymers, carboxymethyl-starches, celluloses modified by grafting or crosslinking, and acrylic copolymer; it is also possible to make provision for the sheet of expanded structure to be dusted with a deodorising material which can act by chemical neutralisation of the odour-generating products or by absorption of the odours. According to a second embodiment of this variant, the sheet of expanded structure, which is arranged inside the absorbent mass, possesses sufficiently large meshes to give a thickness which is approximately equal to that of the absorbent mass, the constituent elements of the said mass being wadded in the expanded structure, which constitutes the reinforcement for the mass.

If the sheet of expanded structure is in the absorbent mass but does not constitute the reinforcement for the whole of the said absorbent mass,the latter can comprise a plurality of compressed or uncompressed wads; in particular, the absorbent mass can comprise an uncompressed wad, a compressed absorbent core and/or a wad of a retention material chosen from amongst the group comprising carboxymethylcelluloses, polyacrylonitrile/starch graft copolymers, carboxymethyl-starches, celluloses modified by grafting or crosslinking, and acrylic copolymers.

As carboxymethylcelluloses which can be used, there may be mentioned those marketed under the name CLD by BUCKEYE CELLULOSE CORPORATION, under the name PERMASORB 30 and PERMASORB 10" by NATIONAL STARCH, under the name ALGINATE by CECA, under the name BIBULOUS FIBRES-TYPE A by BRITISH CELANESE, and under the name AQUALON by HERCULES. A carboxymethylcellulose of this kind can be presented in the form of a powder, fibres, finely ground fibres, that is to say having a length of less than 1 mm, granules, or a sheet of fibrous structure. In the form of fibres, this carboxymethylcellulose is capable of swelling in water and of absorbing up to 4-99 7 2 g of water per gram of fibres. The major part of the water absorbed in this way can be held efficiently by these carboxymethylcellulose fibres, even if they are subjected to relatively high compression. Another product of high retention which can be used is a polyacrylonitrile/ starch graft copolymer which is capable of swelling in water, in particular a polyacrylonitrile/starch graft copolymer hydrolysed by an aqueous base, in which the nitrile groups have been converted to a mixture of carboxamide and alkali metal carboxylate. After it has been dried in the form of a film in the carboxylate state, this polymer is capable of absorbing several times its own weight of an electrolytic solution reproducing the composition of a urine. An absorbent substance of this type can be used either in the form of a film or in the form of particles. The product marketed under the name SUPER SLURPER by DOITTAU PRANCE may be mentioned as a carboxymethylstarch which can be used as the product of high retention. Fibres of cellulose grafted with polyacrylonitrile may be mentioned as fibres of cellulose modified by grafting or by crosslinking, which can be used as the retention product.

Xn all cases, when the retention products defined above are used, it has been found that placing them in the meshes of a sheet of expanded structure exhibits a very great advantage because, during its absorption of 972 liquid, the product can swell freely in the meshes of the expanded structure; furthermore, if, as a result of excess liquid, the product tends to form a gel of excessively low viscosity, the meshes of the expanded structure mechanically retain the said gel and consequently improve the characteristics of the retention product and of the absorbent element in which it is present. The retention product can be dusted into the meshes of the expanded structure, either in the form of a powder or in the form of fibres.

If provision is made for the sheet of expanded structure to occupy the whole thickness of the absorbent mass, the said absorbent mass is advantageously placed in the meshes of the expanded structure by blowing. In this case, the absorbent mass generally consists of ground wood pulp, and the presence of the expanded structure makes it possible to improve the cohesion of the absorbent mass without it being necessary to increase its compression, and this makes it possible to improve the comfort experienced by the user, a more flexible absorbent mass being used.

If the expanded structure is interposed between the absorbent mass and the layer of the external envelope, which comes into contact with the skin and the mucous membranes of the user, the essential purpose of the expanded structure is to ensure a space between the absorbent mass, which retains the body liquids, and the layer of the external envelope, which is in contact with the skin or the mucous membranes; in this way, the abovementioned layer can be isolated from the moist mass, and this gives the user an impression of improved comfort; moreover, ventilation is established between the abovementioned layer and the moist mass, and this contributes to the drying of the said layer. In a known material. manner, the abovementioned layer can consist of a nonwover/ If the absorbent element is intended to constitute a bandage, for example an adhesive bandage, the abovementioned layer is advantageously a nonwoven material which does not adhere to the wound.

In order to provide a better understanding of the subject of the invention, several embodiments thereof are illustrated in the accompanying drawings, in which; Figure 1 shows, in perspective, a strip of polyethylene sheet which has been subjected to the cutting operation making it possible to obtain an expanded structure; Figure 2 shows the strip of Figure 1, after traction and fixing of the expanded structure; Figure 3 shows a transverse section of a sanitarytowel embodying the invention, which comprises an expanded structure between the absorbent mass and the nonwoven material comprising the external envelope; Figure 4 shows a transverse section of another 499 7 2 variant of a sanitary towel embodying the invention, this variant comprising an expanded structure which is arranged inside the absorbent mass, at the lower part of the latter, and which contains a pulverulent retention product; Figure 5 shows the transverse section of a third variant of a sanitary towel embodying the invention, this variant comprising an absorbent mass blown into an expanded structure which extends over the whole height of the absorbent mass; Figure 6 shows, in transverse section, a bandage embodying the invention and which comprises an expanded structure containing a pulverulent retention product.

With reference to Figure 1, it is seen that 1 designates a polyethylene strip having a thickness of 10 to 100 microns; cuts 2, which are arranged along parallel lines, have been made in this strip, perpendicular to the longitudinal axis of the strip; on one and the same line, the cuts 2 are separated from one another by uncut zones 3. On one and the same cutting line, the zones 3 are shorter than the cuts 2; each cut 2 has a length of 6 mm, for example, and each uncut zone 3 has a length of 2 mm, for example. The cuts 2 in one cutting line have a staggered arrangement relative to the cuts 2 in the two adjacent cutting lines. The cutting lines 2 are spaced 3 mm apart, for example, so that they define, between one another, strips having a width of 3 mm. 4887» When a traction force is applied, in the direction of the arrow F, to the plastics strip pre-cut in this way, the plastics strip is caused to expand and an open mesh 4 is established at right angles to each cut 2. The expanded structure obtained in this way is then subjected to a short tenperature increase and the expanded structure is fixed in this way. A structure of this type has a thickness of about 3 to 4 mm.

With reference to Figure 3, it is seen that the sanitary towel 5 consists externally of a layer 6 of a nonwoven material, which constitutes the external envelope; the said layer surrounds a flexible plastics sheet 7 of U-shaped cross-section; inside the sheet 7 starting from the bottom of the U consisting of the sheet 7, there is a strip 8 of a retention product consisting of carboxymethylcellulose, and then a core 9 consisting of slightly compressed wood pulp; the core 9 is compressed at a value which is such that its volume after compression is three times less than its volume before compression; inside the sheet 7, there is also a wad of uncompressed wood pulp, 10, and then a wad 11 produced using the material shown in Figure 2, the wad 11 being covered with an internal layer of nonwoven material 12. On that face of the sanitary towel 5 which is opposite the face where the two nonwoven layers 6 and 12 are located, an adhesive strip 13, covered with protective silicone-treated paper 14, has been provided.

The sanitary towel of which the constitution has now been described exhibits the advantage of having a wad 11 which isolates, from the absorbent mass, the nonwoven layers 6 and 12 which are in contact with the mucous membranes of the user. As a result, the comfort experienced by the user is increased because the sensation of moistness is reduced. Moreover, the presence of this expanded structure 11 near the non-woven layers 6 and 12 permits a certain aeration and drying of these layers.

Figure 4 shows the transverse section of another sanitary towel. Xn the same way as the previous towel, the towel 15 comprises an external envelope 16 made of a nonwoven material and inside which there is a plastics sheet 17 of U-shaped cross-section. Starting from the bottom of the U which constitutes the sheet 17, it is seen that a wad 18, consisting of the material of expanded structure and shown in Figure 2, then a wad 19 which is identical to the wad 9 of the towel in Figure 3, and then a wad 20 which is identical to the wad 10 of the towel in Figure 3, have been arranged inside the towel. This unit is covered with a non-woven layer 21. A strip of an adhesive product, 22, covered with a protective sheet 23 of silicone-treated paper, has been placed on that face of the towel which is opposite the face on which the two non-woven layers 21 and 16 are located. 9 72 In this embodiment, the wad 18 of material of expanded structure has been dusted with a pulverulent retention product consisting of carboxymethylcellulose.

The purpose of the expanded structure of the wad 18 is to form a reinforcement for the retention product when the latter absorbs the liquid. It is appropriate to point out that the meshes of the expanded structure allow the particles of the retention product to swell freely, but hold the said product in the case where excess liquid would tend to convert it into a gel of excessively low viscosity. The wad 18 has 'also been dusted with a deodorising product. This product can be an activated wood charcoal or a clay, vdiich absorbs the odours by adsorption, or also, particularly in the case of baby nappies, a slightly acid neutralisation product intended for neutralising the ammonia which appears. On both its material faces the wad 18 is associated with an envelope of nonwovei/ the said envelopes retaining the dusted products in the structure whilst the wad 18 is being used to manufacture the sanitary towel 15.

Figure 5 shows a third variant of a sanitary towel 24 which, in the same way as the previous two towels, comprises an external envelope of nonwoven material 25, on the lower face of which an adhesive strip 26, protected by a strip 27 of silicone-treated paper, has been provided.

A flexible plastics sheet 28 of U-shaped cross-section has been arranged inside the envelope of nonwoven material, . Inside the sheet 28, there is an absorbent mass 29 comprising a plastics sheet of expanded structure, which occupies the whole thickness of the said absorbent mass.

Fibres of wood pulp have been blown into the expanded structure of the wad 29 in order to form an absorbent mass for which the internal reinforcement consists of the strips of undulated plastic of the expanded structure. The mechanical strength of the absorbent mass can thus be improved without it being necessary to compress the latter, with the result that the absorbent mass can remain perfectly flexible, thus increasing the comfort experienced by the user. An internal non-woven layer 30 has been arranged on top of the wad 29.

Figure 6 shows, in transverse section, a bandage which consists of an adhesive cloth 31 on which a sheet of expanded structure 32, which has been dusted with a pulverulent retention product consisting, for exanple, of carboxymethylcellulose, has been placed. The expanded structure 32 is covered with a nonwoven material 33, which adheres to the adhesive cloth 31 and which has the property of not sticking to wounds. This bandage makes it possible to ensure aeration above the wound, whilst at the same time permitting the absorption and the retention of the physiological liquids.

Claims

1. An absorbent element, in particular a sanitary towel, baby nappy, draw-sheet or bandage, which comprises an envelope at least part of which consists of a layer intended to come into contact with the mucous membranes, the dermis or the epidermis of a user of the absorbent element and, within the envelope, an absorbent mass capable of absorbing and retaining a liquid, at least one sheet of a flexible material of expanded structure being included inside the envelope.

2. An element according to claim 1, wherein the sheet of flexible material of expanded structure has been obtained from a sheet of plastics, paper, non-woven material, elastic material or complex or sandwich material, by cutting the sheet to form parallel and staggered cuts, then expanding under a traction which is substantially perpendicular to the abovementioned cuts, and finally fixing the expanded structure so produced.

3. An element according to claim 2, wherein the expanded structure has been fixed by subjecting the sheet to the action of heat.

4. An element according to claim 2, wherein the expanded structure has been fixed by having been coated with a binder and then dried. 4 9872

5. An element according to claim 2, 3 or 4, in which the sheet converted to an expanded structure comprises polyethylene, polypropylene, polyester or polyamide. 5

6. An element according to claim 2, 3 or li, in which the sheet converted to an expanded structure is a sheet of ordinary, creped, wadded or impregnated paper.

7. An element according to claim 2, 3 or 4, in which the sheet converted to an expanded structure is a sheet comprising a hydrophobic layer and a hydrophilic layer .

8. An element according to claim 7, wherein the hydrophobic layer of the complex material is a layer of plastics, and the hydrophilic layer of the said complex material is a layer of cellulose wadding.

9. An element according to any preceding claim wherein the sheet of expanded structure is arranged between a layer of the external envelope and 2o the absorbent mass .

10. An element according to any one of claims 1 to 8 wherein the sheet of expanded structure is arranged inside the absorbent mass.

11. An element according to any preceding claim 25 wherein the absorbent mass conprises a plurality of compressed and/or uncompressed wads.

12. An element according to claim 10 wherein the absorbent mass comprises an uncompressed wad, a compressed absorbent core and/or a wad of a retention material chosen from the group comprising carboxymethylcellulose, polyacrylonitrile/starch graft copolymers, carboxymethyl-starches, celluloses modified by grafting or crosslinking, and acrylic copolymers.

13. An element according to claim 10 wherein the sheet of expanded structure is dusted with a retention material chosen from the group comprising carboxymethylcelluloses, polyacrylonitrile/starch graft copolymers, carboxymethyl-starches, celluloses modified by grafting or crosslinking, and acrylic copolymers.

14. An element according to claim 9 or 12 wherein the sheet of expanded structure is dusted with a deodorising material.

15. An element according to claim 14 ’ wherein the deodorising material is adapted to act by chemical neutralisation of odour-generating products or by adsorption.

16. An element according to claim 10 wherein the sheet of expanded structure comprises sufficiently large meshes to give a thickness which is substantially equal to that of the absorbent mass, the constituent elements of the mass being wadded in the expanded structure, which constitutes a reinforcement for the mass.

17. Absorbent elements constructed and arranged substantially as herein described with 5 reference to and as illustrated in the accompanying drawings.