SE470064B - Absorbent fiber structure including heat shrunk, spiralized, elastic thermoplastic bicomponent fibers - Google Patents

Description

470 064 2 10 15 20 25 30 35 material, wherein the superabsorbent material is retained in the fiber structure mainly by mechanical locking in the turns of the spiralized bicomponent fibers.

In a preferred embodiment, the main components of the bicomponent fibers are two types of polypropylene, with different melting points and different shrinkage properties.

In other embodiments, the main components of the bicomponent fibers are polypropylene and polyester.

In a further embodiment, the fiber structure comprises hydrophilic fibers such as, for example, viscose fibers, polyester fibers or cellulose fluff pulp.

In yet another embodiment, the fiber structure comprises thermoplastic binder fibers of, for example, polypropylene or polyethylene.

In a further embodiment, the fiber structure has the shape of the ten to a strictly rolled fiber mat.

The invention further comprises an article such as a diaper, a sanitary napkin, or an incontinence guard. The article according to the invention is mainly characterized in that it has an absorption layer comprising a fiber structure of the type indicated above.

In one embodiment, the absorbent body has an insulating layer, which is applied to the side of the absorbent layer which is intended to face a user, and which consists of a porous, substantially non-absorbent, hydrophilic nonwoven fabric.

In another embodiment, the article is a diaper having a back portion intended to be turned backwards on the user during the use of the article, a front portion intended to be turned forwards on the user during the use of the article, and one between the back portion and 10 470 G64 3 narrower crotch portion located in the front, which in use is intended to be located in the crotch area, between the user's legs, and further comprising elastic means extending in the longitudinal direction of the diaper to form elastic leg waistbands, the elastic means consisting of a fibrous mat rolled into a string. spiral bicomponent fibers of the side-by-side type, as well as superabsorbent particles.

By mixing, as according to the invention, shrinkable bicomponent fibers of side-by-side type, in a fiber structure, it is possible to obtain a high degree of mechanical retention of particulate material in the fiber structure. It is then essential that the two components of the shrink fibers shrink to a different extent during heat treatment. This is because the shrunken fibers form spirals, in the windings of which the superabsorbent particles and other components included in the fiber structure can be retained. The shrunk bicomponent fibers have high extensibility and resilience, whereby the retained particles have a certain degree of freedom of movement in the fiber structure. This is particularly advantageous, since the risk of the particles coming loose and falling out of the fiber structure, when handling it, is less than in the case of fiber structures where the particles are bound, for example, by means of fusible binder. Such solid bonds can be easily broken, by mechanical action of the fiber structure and thereby lose their effect. In addition, a fiber structure according to the invention allows virtually unobstructed swelling of the superabsorbent particles, as these absorb liquid, since the fiber spirals stretch in step with the swelling of the superabsorbent.

The invention will be described in more detail below with reference to exemplary embodiments shown in the accompanying drawings.

Figure 1 shows a superabsorbent grain, held by a spiralized bicomponent fiber. 4-70 064 10 15 20 25 so '35 4 Figure 2 shows a section along the line II-II through the bicomponent fiber in figure 1.

Figure 3 shows a diaper comprising an absorbent fiber structure according to the invention and Figure 4 shows a section along the line IV-IV through the diaper in Figure 3.

The bicomponent fiber 1 shown in Figures 1 and 2 is of so-called side-by-side type which, as the name suggests, means that its two components 2, 3 are located next to each other, in the longitudinal direction of the fiber. It is essential for the invention to select fiber components with different shrinkage properties. In heat treatment of such a bicomponent fiber, the two components shrink to varying degrees so that one side of the fiber becomes shorter than the other side, whereby the fiber twists and contracts into a spiral. A suitable bicomponent fiber is sold by Chisso Corporation, Osaka, Japan under the name EP-HS 2 and is a 2 denier thick shrink and melt fiber of two different polypropylenes, with a high and a low melting point.

As shown in Figure 1, the spiralized fiber 1 can mechanically hold particles 4, for example superabsorbent grains, in its windings. Such retention is, as previously mentioned, elastic, so that it allows some mobility of the retained particles and allows them to swell upon absorption.

In this context, the term particles shall be given a relative interpretation and shall be considered to include superabsorbent grains as well as granules, flakes and short fibers. Superabsorbents usually refer to materials which are able to absorb several times their own weight of liquid and thereby swell and form a non-water-soluble gel without losing their original particle shape. There are a number of variants of superabsorbents with different chemical composition. For the invention, however, the chemical composition of the superabsorbent is irrelevant, whereby it is possible to use any particulate superabsorbent which has been found to have suitable absorption properties for the purpose. Of course, mixtures of different superabsorbents can also be used.

The diaper shown in Figure 3 comprises a liquid-permeable cover layer 6, for example of non-woven fabric or perforated plastic film, a liquid-impermeable cover layer 7, for example of plastic film or hydrophobic non-woven fabric, and an absorbent body 8 enclosed between these two layers 6, 7. The diaper is intended to be worn as a pair absorbent trousers and is for this purpose formed with a rear part 9, intended to be turned backwards on the user when using the article, a front part 10, intended to be turned forwards on the user during use, and one located between the rear part and the front part narrower crotch portion 11, which in use is intended to be located in the crotch region, between the user's legs. In order for the diaper to be fastened together to the desired trouser shape during use, tape tabs 12, 13 are arranged at both side edges 14, 15 of the diaper, near the rear waist edge 16 of the diaper. The tape tabs 12, 13 are attached in use to the outside of the front of the diaper near front waist edge, whereby the diaper is held together around the wearer's waist. Furthermore, the diaper comprises elastic members 18, 19, which extend over the diaper in a V-shaped pattern with the V-tip located at the front waist edge 17 of the diaper, and with the legs extending towards the rear waist edge 16 of the diaper and terminated adjacent the two tape tabs 12. 13. The elastic members consist of a fiber mat of bicomponent fibers, which is sprinkled with superabsorbent particles and rolled together into a strand 20, as shown in section in Figure 4. The coiled fiber strand 20 has then been heat treated so that the bicomponent fibers are partly spiraled. to some extent melted.

Thereby, the superabsorbent is held in the fiber structure at the same time as the melt binds the fiber mat and keeps it in the rolled-up state. Due to the shrinkage of the fibers, the fiber strand 20 acquires a certain elasticity and can therefore be used as elastic means 18, 19 for sealing and tightening around the leg edges of a diaper.

In the diaper of Figure 3, the elastic members 18, 19 are shown in an extended condition. During use of the diaper, however, the elastic members 18, 19 contract and form elastic raised waistbands around the wearer's legs. Unlike conventional elastic members, which usually consist of elastic bands, or threaded elastic threads, the elastic members made according to the invention are extremely soft and comfortable and do not chafe or irritate the user's skin. The elastic members 18, 19 on the diaper in Figures 3-4 also allow the passage of air and water vapor while preventing liquid flow out of the diaper by the superabsorbent absorbing and chemically binding the liquid reaching the elastic members. This of course contributes to the diaper feeling dry and comfortable to wear.

The absorbent body 8 of the diaper consists of an insulating layer 21, located on the side of the absorbent body 8, which faces the liquid-permeable cover layer 6, and an absorbent layer 22, located on the side of the absorbent body 8, which faces the liquid-impermeable cover layer. 7. The insulating layer 21 is suitably a porous, non-absorbent but hydrophilic nonwoven fabric which rapidly passes body fluid to the underlying absorbent layer 22. The insulating layer 21 further prevents liquid from being transported back from the absorbent layer 22 to the liquid-permeable cover layer 6.

According to the invention, the absorption layer 22 consists of a structure with retained superabsorbent particles. A fibrous structure found to have suitable properties includes 40 weight percent polypropylene / polyethylene bicomponent fibers 2 deniers thick, 40 weight percent polyester fibers of 17 dtex thickness, 20 weight percent viscose fibers of 1.7 dtex thickness, and superabsorbent particles. The superabsorbent particles are retained, as previously mentioned, in the fiber structure by heat-treating it so that the bicomponent fibers are spiraled. In that the bicomponent fibers partially melt during the heat treatment, they also serve as a binder for the fiber structure itself.

A number of alternative fiber mixtures for the absorbent layer are of course conceivable. For example, it is possible to change the proportion of the different fibers, as well as the thickness of the fibers. In addition, other types of absorbent or non-absorbent fibers may be used, for example cellulose fluff, cotton, viscose, polyethylene fibers, polyester fibers, polypropylene fibers or polyamide fibers. However, it is preferred that the fiber structure comprise at least 10% side-by-side type bicomponent fibers, since the bonding effect achieved at lower mixing ratios is almost negligible. Furthermore, the absorbent layer itself may consist of different layers with mutually different fiber mixtures or with different amounts of superabsorbent. For example, it may be advantageous to provide a first layer with relatively low absorption capacity and relatively high throughput and high resilience on the side of the absorption layer which is intended to face the user. Such a layer is soft against the user's body and contributes to the surface which abuts the user during use feeling dry. This is achieved by the layer containing a relatively large proportion of non-absorbent fibers, for example polypropylene, polyethylene, polyester or polyamide and only a small amount of superabsorbent.

Outside the first layer, a second absorbent layer is arranged, with high liquid dispersibility within the layer itself and high absorption capacity. Such properties are obtained if the layer has a large proportion of hydrophilic, liquid-transporting fibers, for example cellulose fibers, and contains relatively much superabsorbent, suitably about 1 g of superabsorbent / 5 g of fibers.

The absorbent body in the diaper in Figures 3-4 can of course also comprise additional components such as special spreading layers or reinforcement layers, as well as additional absorbent layers, for example of cellulose fluff pulp. 10 15 20 25 * Cl CD 64 8 The described absorbent fiber structure can of course be used in absorbent articles other than diapers. For example, it is particularly well suited for sanitary napkins, which by the invention can be made thin, discreet and comfortable and nevertheless have a high absorption capacity. The possibility of obtaining high absorption capacity in a small, discreet article is further highly appreciated in absorbent protection for incontinent adults. The absorbent fiber structure can also be used in tampons, compresses and dressings as well as various types of cloths and protection, for example bed protection or chair protection.

A fibrous structure particularly suitable for dressing purposes, soft, flexible and resilient fiber structure is obtained with about 70% by weight of EP-HS 2 fiber and about 30% by weight of viscose fibers.

The fibrous structure may, of course, include additional components, such as odor control agents or agents that promote wound healing. The invention is not to be construed as being limited to the embodiments described herein, but a number of further modifications are conceivable within the scope of the appended claims. * a

Claims (9)

10 15 20 25 30 470 064 'Patent claim Absorbent fiber structure, characterized in that the structure comprises a mixture of heat-shrinkable, spiralized, elastic thermoplastic bicomponent fibers (1), the constituent components (2,3) having mutually different shrinkage properties and being present in side-by-side ratio, and at least one type of superabsorbent particulate material (4,5) wherein the superabsorbent material (4,5) is retained in the fiber structure mainly by mechanical locking in the turns of the spiral bicomponent fibers (1). Absorbent fiber structure according to claim 1, characterized in that the main components (2,3) of the bicomponent fibers (1) are two different types of polypropylene. The absorbent fiber structure according to claim 1, characterized in that the main components (2,3) of the bicomponent fibers (1) are polypropylene and polyester. Absorbent fibrous structure according to any one of claims 1-3, characterized in that it comprises hydrophilic fibers such as, for example, viscose fibers, polyester fibers or cellulose fluff pulp. Absorbent fibrous structure according to any one of the preceding claims, characterized in that it comprises thermoplastic binder fibers of, for example, polypropylene, polyethylene or thermoplastic bicomponent fibers. Absorbent fiber structure according to any one of the preceding claims, characterized in that it has the shape of a fiber mat rolled up into a strand (20). Absorbent article, such as a sanitary napkin, a diaper, a wound, a dressing or an incontinence guard, comprising an absorbent body (8) enclosed in a casing (6, 7) having a liquid-permeable area (6) at the side of the article which in use is intended to face a user and a liquid-impermeable area (7) at the side of the article which in use is intended to face away from a user, characterized by that the absorbent body (8) has an absorbent layer (22) with a fiber structure comprising a mixture of heat-shrinkable, spiralized, elastic thermoplastic bicomponent fibers (1), the constituent components (2,3) having mutually different shrinkage properties and being present side by side -side ratio, and at least one type of superabsorbent particulate material (4,5) wherein the superabsorbent material (4,5) is retained in the fiber structure mainly by mechanical locking in the windings of the spiralized bicomponent fibers (1). Absorbent article according to claim 7, characterized in that the absorbent body (8) has an insulating layer (21), which is applied to the side of the absorbent layer (22) facing the liquid-permeable area (6) of the casing, and that the insulating layer (21 ) consists of a porous, substantially non-absorbent, hydrophilic nonwoven fabric. Absorbent article according to claim 7 or 8 in the form of a diaper, characterized in that it has a back portion (9), intended to be turned backwards on the user during use of the article, a front portion (10), intended to be use be turned forward on the user, and a narrower crotch portion (11) located between the rear portion (9) and the front portion (10), which in use is intended to be arranged in the crotch area, between the user's legs, and further comprising elastic members (18, 19 extending in the longitudinal direction (15) of the diaper to form elastic leg bands, the elastic members (18, 19) being constituted by a fibrous mat rolled into a strand (20) comprising crimped spiralized bicomponent fibers "11" GJ 11-70 064 '11 (1) of side-by-side type, and superabsorbent particles (4,5).