NL8004404A - ABSORBENT ELEMENT INCLUDING AT LEAST ONE SHEET OF PLASTIC MATERIAL WITH OPENED STRUCTURE. - Google Patents

Description

1 * F.O. 29,324

Absorbent element comprising at least one sheet of plastic material with an open structure.

The invention relates to absorbent elements or products, such as sanitary napkins, diapers for babies, stitch sheets for incontinent persons or adhesive bandages.

It is already known to manufacture metal mesh sheets from a metal plate which are known under the name "expanded metal" ("Métal dêployé"). In order to obtain such an open structure, the sheet forming the starting material is cut along parallel lines, the cutting zones being separated from each other by narrow non-cutting zones, the cutting zones of one line being offset from cutting zones of the two adjacent lines and the metal thus pre-cut is subjected to a tensile force which allows the formation of meshes at each cut zone.

It has already been proposed to apply the same technique replacing the metal plates with sheets of flexible plastic material: in this case the cutting takes place in the same way as with metal plates but the pulling force is applied perpendicular to the cutting lines, thanks to which the meshes are formed, must be followed by a fixing phase due to the flexibility of the sheet 20 of plastic material. This fixing phase is carried out either by heat treatment or by applying an adhesive, for example by spraying and drying said adhesive on the drawn material. In all cases, the resulting material forms a sheet which has a relatively great thickness in the transverse direction due to the deformation applied to each tape of the sheet of plastic material, which tape is bounded by two successive cutting lines.

Due to the staggered displacement of the cutting zones of the two successive cutting lines, each belt is connected to two adjacent parallel belts at points which are staggered along their edges and when the tensile force is applied to the sheet of plastics material, which is pre-cut, openable, the staggered placement of the tape attachment points causing a corrugation of said tape on either side of the pre-cut blank.

This undulation develops an open structure which has a transverse thickness which is a function of the tensile force exerted on the pre-cut material exerted 800 44 04 ir 2 and of the thickness of the starting tapes, which thickness may be between the thickness of the plastic material blank and double the spacing between two consecutive parallel cutting lines, that is, double the width of the belts subjected to corrugation at the time of opening.

It has been found that flexible sheets of plastic material thus opened can be obtained which have a very low weight and have a transversal thickness which is relatively large. These sheets remain flexible despite the formation of meshes after the opening of the material and they have a large number of meshes which form small openings regularly distributed over the entire surface of the sheet. The same stretching technique can, of course, be applied to all flexible sheets, for example, sheets of rubbery masterial, plain creped or roughened paper, made of non-woven material by the dry or wet route. One can also envisage stretching sheets formed of complex materials, for example sheets of plastic material and cellulose wadding, the opening of the pre-cut material causing a tiling of the two layers of complex material, which is preferred when joining these two layers together.

The object of the invention is to provide absorbent elements or products such as, for example, sanitary napkins, diapers for babies, stitch sheets for incontinent persons or adhesive bandages, for example. All these elements or products have a substantially flat shape and enclose an absorbent mass. This absorbent mass may contain various constituent parts, but in any case it is intended to absorb physiological fluids and to retain them in the interior of the element. An absorbent element of this type is wrapped with an outer sheet, which is, for example, made of a non-woven material, which sheet generally comes into contact with the skin or mucous membranes of the user. It is important to obtain comfort that the outer sheet, which forms the outer wrap of the absorbent element, remains as dry as possible. Thus, it is desirable that this sheet be either separated from the absorbent mass by material which, on the one hand, allows the physiological fluids to pass to the absorbent core and, on the other hand, maintains a distance between the outer wrap and the absorbent material.

According to the invention it is proposed for this purpose to provide a sheet of flexible material with opened structure, which sheet can be formed by pre-cutting and stretching a sheet of plastic material, a sheet of rubber-like material , a paper sheet, a non-woven sheet, a "sandwich" sheet or other similar sheets. The material which is the starting point for the opened structure sheet used according to the invention simply needs to be a flexible material for the opened structure sheet to retain sufficient flexibility to be comfortable for the user of the obtained absorbent element.

As a result, the invention has for its object to provide an absorbent element, in particular a sanitary napkin, a diaper for babies, a stitch sheet or a bandage, comprising in the interior an absorbent mass which can absorb and retain a liquid, and externally an enclosure surrounding said mass and at least part of which is formed from a sheet intended to come into contact with the mucous membranes, dermis or epidermis of the user, characterized in that inside the envelope has at least one sheet of flexible material with an open structure.

According to a preferred embodiment, the sheet of flexible material with opened structure is obtained by cutting parallel and staggered cutting lines, then stretching with a force perpendicular to the said cutting lines and finally fixing the opened structure thus obtained, starting from a sheet from plastic material, paper, non-woven material, elastic material, or composite material or "sandwich"; fixing of the opened structure is carried out by subjecting the sheet to the influence of heat after application of the tensile force, or to applying adhesive, followed by drying.

When the sheet converted to an opened structure is a sheet of plastic material, it may preferably be formed of polyethylene, polypropylene, polyester or polyamide. If the sheet converted into an open structure is a sheet of paper, it may be a sheet of plain paper or a creped or roughened paper or also impregnated paper, for example, by means of a plastic material. When the opened structure is obtained from a sheet of complex material, it can advantageously be formed from a hydrophobic layer and a hydrophilic layer; the hydrophobic layer can be formed from plastic material while the hydrophilic layer is formed from cellulose wadding.

40 In the case of opened complex materials with a hydrophilic surface and a hydrophilic surface, the example of open complex material obtained from a flocked plastic material, the flocking taking place according to usual techniques, and the fiber used then a hydrophilic one must be mentioned. fiber is wood pulp, viscose, cotton, and so on.

According to a first variant, the absorbent element according to the invention comprises at least one sheet with opened structure placed between the outer enveloping sheet and the absorbent mass.

According to another variant, the absorbent element according to the invention comprises at least one sheet with opened structure placed on the interior of the absorbent mass. In this case, according to a first embodiment, the opened-structure sheet may be sprayed with a retention material selected from the group consisting of carboxymethyl cellulose, grafted polyacrylonitrile amidone copolymers, carboxyme thylamidones, grafted or cross-linked celluloses, and acrylic copolymers; it is also possible to provide that the opened-structure sheet is sprinkled with a deodorizing material which can cause chemical neutralization of products that develop odors or absorb odors. According to a second embodiment of this variant, the open-structure sheet placed on the interior of the absorbent mass comprises meshes sufficiently large that it can have substantially a thickness equal to that occupied by the absorbent mass, wherein the constituent elements of said mass as layers are placed in the opened structure, which forms reinforcement.

If the open-structure sheet is in the absorbent mass but does not form the reinforcement of the cohesion of said absorbent mass, it may have a number of compressed or non-compressed layers; in particular, the absorbent mass may have an uncompressed layer, an absorbent core which has been compressed and / or a layer of retention material selected from the group consisting of carboxy methyl celluloses, grafted polyacrylonitrile amidone copolymers, carboxy thylamidones, grafting or cross-linking modified celluloses, and acrylic copolymers.

As the carboxymethyl celluloses useful, the following commercially available materials may be mentioned: under the name "CLD" of "BUCKEYE CELLULOSE CORPORATION", under the names "PERMASORB 30" and "PEEMASORB 10" of "NATIONAL STARCH under the name "ALGINATE" of "CECA", under the name "BIBULOUS FIBERS TYPE A" of "BRITISH CELANESE", under the name "AQUAL0N" of "HERCULES". A carboxymethyl cellulose of this type can be present in the form of a powder, of fibers, of 8Θ0 4 4 04 5 finely ground fibers, that is, of a length less than 1 mm, of granules or in the form of a fibrous sheet structure. This carboxymethyl cellulose in the form of fibers is able to swell in water and absorb up to 25 g per gram of fiber. Most of the water thus absorbed can be appropriately retained by these carboxymethyl cellulose fibers, even if subjected to relatively high compression. As a high retention product, it is also possible to use a grafted copolymer of polyacrylonitrile amidone which can swell in water, and in particular a grafted copolymer of polyacrylonitrile amidone hydrolyzed with an aqueous base, the nitrile groups being converted into carboxyamide groups and / or or alkali metal carboxylate groups. After being dried in the form of a film in a carboxylate state, this polymer can absorb many times its own weight from an electrolytic solution that reproduces the composition of a urine. Such an absorbent can be used either in the form of a film or in the form of particles. As the carboxymethylamidone useful in so far as it provides strong retention, it may be mentioned that it is marketed under the name "SUPER SLURPER" by "DOITTAU FRANCE". Polyacrylonitrile-grafted cellulose can be referred to as cellulose modified by grafting or cross-linking, where useful as a retention product.

In all cases, as used with the aforementioned retention products, it has been found that placing them in the meshes of an open structure sheet obtains a great advantage because the product can swell freely in the meshes during its absorption of liquid. the open structure; moreover, if, due to excess liquid, the product tends to form a gel with a very low viscosity, the meshes of the opened structure mechanically retain said gel 30 and thereby improve the properties of the retention product and of the absorbent element contained therein is. The retention product can be sprinkled into the meshes of the opened structure either in the form of a powder or in the form of fibers.

If the open-structure sheet is intended to occupy the entire thickness of the absorbent mass, it is advantageous to place this absorbent mass in place by blowing into the meshes of the open structure. The absorbent mass is then generally formed from defibrillated wood pulp and the presence of the open structure allows to improve the consistency of the absorbent mass without the need to increase its compression 8004404 * 6, allowing improve user comfort by applying a more flexible absorbent mass.

When the opened structure is interposed between the absorbent mass and the sheet of the external wrap that contacts the skin and mucous membranes of the user, the purpose of the opened structure is primarily to provide a space between the absorbent mass, which retains the body fluids, and the skin of the external wrap, which is in contact with the skin or mucous membranes, in such a way that said skin can be insulated from the moist mass, giving the user the impression of improved comfort. Among other things, between the said sheet and the moist mass, a ventilation is caused which contributes to the drying of said sheet. The above sheet can be formed in known manner by means of a non-woven material. When the absorbent element is intended to form a bandage, for example an adhesive bandage, said sheet is preferably a nonwoven material that does not adhere to the wound.

The invention will be described in more detail below with reference to a drawing, in which exemplary embodiments are shown.

FIG. 1 shows a perspective view of a sheet of polyethylene sheet cut to obtain an opened structure.

Fig. 2 shows a belt according to FIG. 1, performing a tensile force and fixing the opened structure.

Fig. 3 shows a cross section of a sanitary napkin according to the invention comprising an opened structure between the absorbent mass and the nonwoven material of the outer sheath.

Fig. 4 shows the cross-sectional view of another embodiment of a sanitary napkin according to the invention, this variant comprising an opened structure placed in the interior of the absorbent mass at the lower part thereof and enclosing a powdered retention material.

Fig. 5 shows the cross section of a third variant of a sanitary napkin according to the invention, which variant comprises an absorbent mass blown into an open structure that extends over the entire height of the absorbent mass.

Fig. 6 shows a cross-sectional view of a dressing according to the invention comprising an opened structure enclosing a powdery retention product.

In Fig. 1, 1 shows a polyethylene tape with a thickness of 40 to 10 microns; perpendicular to the longitudinal axis of the belt, cutting lines 2 have been arranged in this belt, which lines have been placed along parallel lines; on the same line, the incisions 2 are separated from each other by non-cut zones 3. On the same cutting line, the zones 3 have a length smaller than the cutting lines 2; for example, each cutting line 52 has a length of 6 mm and each non-cut zone 3 has a length of 2 mm, for example. The cutting lines 2 of one cutting line are staggered with respect to the cutting lines 2 of the two adjacent cutting lines. The cutting lines 2 are placed, for example, at a distance of 3 mm from each other so that they form belts between them having a width of 3 mm.

When the plastic material tape thus cut is exerted a tensile force in the direction of the arrow F, the plastic material tape is opened, with an open mesh showing at each cutting line 2. Subsequently, subject The opened structure thus obtained is subjected to a short temperature increase and fixation of the opened structure is then obtained. Such a structure has a thickness of about 3 to 4 mm.

In Fig. 3, the sanitary napkin according to the invention is indicated in its entirety by 5. The dressing 5 externally comprises a non-woven sheet 6 which forms the external wrapping; said sheet surrounds a sheet of flexible plastic material 7 with a cross section in the form of; in the interior of the sheet 7, starting from the transverse leg U formed by the sheet 7, there is a plate 8 of a retention material formed by carboxymethyl cellulose, then a core 9 formed by wood pulp which has been slightly compressed; the core 9 is compressed to a value such that its volume after compression is three times smaller than its thickness before compression; in the interior of the sheet 7 there is also a layer 10 of wood pulp that is not compressed, then a layer 11 formed by means of a material shown in Fig. 2, the layer 11 being covered with a staple -woven part 12. On the surface of the sanitary napkin 5, which is opposite that where the two non-woven layers 6 and 12 are located, an adhesive tape 13 has been applied which is coated with a silicone-treated protective paper 14.

The sanitary napkin, the composition of which has been described, has the advantage that a layer 11 is present which insulates the absorbent mass from the non-woven materials 6 and 12, which are in contact with the mucous membranes of the user. As a result, the user's comfort is increased because the sense of humidity has disappeared. Moreover, after the presence of this opened structure, in the vicinity of the non-woven sheets 6 and 12, a certain air flow increases and a drying of these sheets.

Fig. 4 shows a cross section of another sanitary napkin according to the invention, which sanitary napkin is indicated in its entirety by 5. Like the previous sanitary napkin, the napkin 15 comprises an outer sheath of nonwoven material 16, inside of which there is a sheet of plastic material 17 with a U-shaped cross section. Starting from the cross leg of U, which forms the sheet 17, it is seen that in the interior of the bandage a layer 18 10 has been placed formed of material with open structure shown in fig. 2, then a layer 19 identical to the layers 9 of the bandage of FIG. 3, then a layer 20 identical to the layer 10 of the bandage of FIG. 3. This assembly is covered with a nonwoven sheet 21. In the plane of the bandage opposite that where the two 15 nonwoven sheets 21 and 16, a strip of adhesive 22 is applied, which is covered by a silicone treated protective paper 23.

In this embodiment, the open structure material layer 18 is sprinkled with a powdered retention material formed by carboxy-methylcellulose. The role of the open structure of the layer 18 is to form a reinforcement for the retaining product as it absorbs the liquid. It should be noted that the meshes of the opened structure allow free swelling of the particles of the retention product, but retain this in case excess liquid tends to form into a gel of very low viscosity. The layer 18 is also sprinkled with a deodorizing agent. This agent can be either charcoal or a clay that absorbs the odors by adsorption or, especially in the case of diapers for babies, a neutralization product which is slightly acidic and is intended to neutralize the ammonia present. The layer 18 is connected on its two faces to a non-woven sheet, which sheet holds the products scattered in the structure during the treatment of the layer 18 to produce the sanitary napkin 15.

Fig. 5 shows a third embodiment variant of a sanitary napkin according to the invention. This sanitary napkin is indicated in its entirety by 24; like the two previous bandages, it comprises an outer nonwoven sheath 25 on the inner surface of which is applied an adhesive tape 26 protected by a tape 27 of silicone treated paper. In the interior of the nonwoven sheath 40, a sheet of flexible, plastic material 28 has been placed with 800 44 04 9 - a U-shaped cross section. In the interior of the sheet 28 there is an absorbent mass 29 containing a sheet of open structure plastic material which sheet occupies the entire thickness of said absorbent mass. Wood pulp is blown into the opened structure of the layer 29 to form an absorbent mass which has as internal reinforcement the walls of corrugated plastic material of the opened structure. Thus, it is possible to improve the mechanical behavior of the absorbent mass without the need to perform compression of the latter so that the absorbent mass can remain perfectly smooth, thereby enhancing user comfort. An inner non-woven sheet 30 is placed above the layer 29.

Fig. 6 shows in cross section the dressing according to the invention.

This bandage is formed by an adhesive sheet 31 on which is placed an open structure sheet 22 which has been sprinkled with powdered retention agent, for example, formed from carboxymethyl cellulose.

The opened structure 32 is coated with non-woven material 33 that adheres to the adhesive sheet 31 and has the property of not adhering to wounds. The dressing according to the invention which has been described makes it possible to ensure an air supply above the wound while allowing absorption of physiological fluids and retaining them.

8004404

Claims (15)

An absorbent element, in particular sanitary napkins, diapers for a baby, stitch sheet or bandage, comprising internally an absorbent mass which can absorb and retain a liquid and is externally provided with a wrapping covering said mass and of which at least part is formed from a sheet intended to come into contact with the mucous membranes, dermis or epidermis of the user, characterized in that at least one sheet of a flexible material is placed in the interior of the casing 10 with opened structure. 2. Element as claimed in claim 1, characterized in that the sheet of flexible material with an open structure is obtained by cutting along parallel cutting lines which stagger relative to each other, then opening them using a force substantially perpendicular to said cutting lines and finally fixing the opened structure thus prepared from a sheet of plastic material, paper, nonwoven material, elastic material or composite or "sandwich" material. 3. Element according to claim 2, characterized in that the fixing of the opened structure is carried out by subjecting the sheet to a heat treatment or to an addition of an adhesive followed by drying it. Element according to one or more of claims 2 or 3, wherein the sheet transformed into an open structure is a sheet of plastic material, characterized in that said sheet is formed of polyethylene, polypropylene, polyester or polyamide. An element according to any of claims 2 or 3 wherein the sheet formed into an open structure is a sheet of paper, characterized in that the sheet is a sheet of plain creped, roughened or impregnated paper. The element according to any of claims 2 or 3, wherein the sheet converted into an open structure is a complex material sheet, characterized in that said sheet is formed from a hydrophobic layer and a hydrophilic layer. Element according to claim 6, characterized in that the hydrophobic layer of the complex material is a layer of plastic material and that the hydrophilic layer of said complex material is a layer of cellulose wadding. 8. Element as claimed in one or more of claims 1 to 7, characterized in that it comprises at least one sheet with opened structure 800 44 04 placed between the sheet of the external wrapping and the absorbent mass. 9. Element according to one or more of claims 1 to 7, characterized in that it comprises at least one sheet with opened structure placed in the interior of the absorbent mass. 10. Element according to one or more of claims 1 to 9, characterized in that the absorbent mass contains a number of compressed or non-compressed layers. Element according to claim 10, characterized in that the absorbent mass comprises an uncompressed layer, a compressed absorbent core and / or a layer of retention material selected from the group formed by carboxymethyl cellulose, grafted polyacrylonitrileamidone copolymers, carboxymethylamidones, by grafting or cross-linking modified celluloses, and acrylic copolymers. Element according to claim 9, characterized in that the open-structure sheet is sprinkled with a retention material selected from the group consisting of carboxymethyl cellulose, grafted polyacrylonitrile amidone copolymers, carboxymethylamidones, grafts or cross-linked celluloses and acrylic copolymers. Element according to either of claims 9 or 12, characterized in that the open-structure sheet is sprinkled with a deodorizing material. Element according to claim 13, characterized in that the deodorizing material acts by chemical neutralization of the substances developing the odors or by absorption. Element according to claim 9, characterized in that the open-structure sheet contains meshes sufficiently large to obtain a thickness substantially equal to that occupied by the absorbent mass, the constituent elements of said mass being placed in the open structure, which forms the reinforcement. 800 44 04