WO2007077216A1

WO2007077216A1 - Cover and transfer layer structure for a hygiene product

Info

Publication number: WO2007077216A1
Application number: PCT/EP2007/000022
Authority: WO
Inventors: Alvaro Garcia; Katja Lerner
Original assignee: Johnson & Johnson Gmbh
Priority date: 2006-01-04
Filing date: 2007-01-03
Publication date: 2007-07-12
Also published as: DE102006000781A1

Abstract

The invention relates to a cover and transfer layer structure for a hygiene product, comprising at least one nonwoven cover layer, containing superabsorbent fibers and multi-component fibers that are produced by calendering, and at least one nonwoven transfer layer, comprising regenerated cellulose-based fibers and multi-component fibers. The invention also relates to an absorbent product, comprising at least one layer structure according to the claims of the invention, at least one absorbent core, especially adjacent to the nonwoven transfer layer of the layer structure, and optionally at least one substantially fluid-impermeable barrier layer facing the side of the absorbent core which is opposite the layer structure.

Description

Cover and transfer layer structure for a hygiene article

description

The present invention relates to a cover and transfer layer structure for a hygiene article and to an absorbent article comprising the cover and transfer layer structure according to the invention.

US 5,728,083 discloses a multi-layered absorbent structure which rapidly absorbs body fluids and also retains larger quantities of fluids. Such absorbent structures may comprise, for example, two respective multi-layer nonwoven layers, between which superabsorbent powder has been interspersed. While the first nonwoven layer comprises a first layer comprising PE / PET bicomponent fibers and cellulose fibers, and a second layer comprising PE / PET bicomponent fibers and PET fibers, the second nonwoven layer is composed of a first layer comprising PE / PET fibers. Bicomponent fibers, a second layer containing PE / PET bicomponent fibers and cellulosic fibers, and a third layer containing PE / PET bicomponent fibers. The entry of superabsorbent particles is technically complicated and requires at least one additional process step. In addition, care must be taken that the superabsorbent particles are not applied too close to the lateral edges of the fleece backing, since otherwise it can not be ruled out that these particles will trickle out of the product ready for sale. In addition, in particular, the fine-grained portions of the superabsorbent powder do not remain in the layer between the upper and the lower nonwoven fabric, but penetrate more or less deeply the respective fleece. This leads to unpredictable absorbent properties.

US 6,452,062 B1 discloses an absorbent structure comprising first and second layers of carded fibers bonded together by needling and thermobonding. Cellulose, viscose, polyester, polyethylene, polypropylene, nylon, ethylene / propylene, copolymer and / or bicomponent fibers can be used in particular for the first layer. The second layer is preferably composed of polyester fibers. By adding bicomponent fibers and fibers provided with a heat-activatable adhesive or powder having a lower melting point than the first and / or second layers, a thermal bonding system is provided which prevents the resulting absorbent article from forming fluff during use. In addition, the resulting absorbent articles retain high resistance to rewet.

US 5,989,688 has a laminate nonwoven structure comprising a first support layer and a first bulky layer for controlled collection and distribution of liquids. While the voluminous layer serves to receive and disperse liquid, the support layer is intended to hold the liquid or transfer it to a liquid holding layer. The voluminous layer can, for. B. by carding or by spunbonding carded fibers. The backing layer may be prepared by a variety of different methods, e.g. B. by carding, spunlaying, wetlaying, drylaying or airlaying.

US 6,608,237 B1 discloses an absorbent article comprising a lower fluid impermeable layer, an upper fluid permeable layer and an absorbent core between the upper and lower layers. The absorbent core may contain, for example, a matrix of hydrophilic fibers, eg cellulose fibers, into which superabsorbent hydrogel-forming particles and optionally synthetic meltblown fibers and / or natural fibers are incorporated. The superabsorbent particles are substantially homogeneously mixed with the hydrophilic fibers but may also have a gradient distribution. The topsheet may comprise natural as well as synthetic fibers, eg cotton fibers, polyester fibers and / or polypropylene fibers. Melt-blown or spun-bonded nonwoven webs of the topsheet are preferably obtained by carding.

US 6,443,936 Bl discloses an absorbent article having a fluid receiving layer adjacent to the topsheet, comprising e.g. Polyester, polypropylene, polyethylene, nylon, viscose or cellulose acetate fibers. This acquisition layer can be obtained by airlaying, wetlaying, meltblowing, spunbonding, carding, thermobonding or air-through-bonding. In a preferred embodiment, the acquisition layer has two laminated layers, a top layer of spunbonded polypropylene and a bottom layer of substantially cellulosic fibers with a lower level of powdery adhesive. The fibers of the lower layer are connected to each other by means of airlaying and to the upper layer.

Finally, US Pat. No. 6,033,769 discloses an absorbent layer structure which comprises inter alia a layer of a water-soluble polymer foam to which a layer of particulate superabsorbent polymer is fixed. In this way, the superabsorbent material should be integrated into a matrix in a simple and reliable manner and at the same time fixed.

The absorbent articles according to the prior art, in particular those which come into contact at least with a surface on the skin, in particular over a relatively long period of time, are still not always perceived as optimal. This applies in particular to absorbent articles which have already absorbed body fluid during wear. Users of such absorbent articles often find themselves lacking softness and spatial extent in the body-facing surface, especially after prolonged wear after moisture absorption. In addition, as usual with panty liners or sanitary napkins, the body-facing surface is moved or displaced relative to the adjacent skin area during wear, an irritation of the skin, caused inter alia by friction effects, is often found. These disadvantageous properties can not readily be eliminated by the absorbent articles described above.

The present invention was therefore based on the object to provide an absorbent sanitary article with a cover layer, which is not subject to the disadvantages of the prior art and especially when worn for a long time after the fluid wetting feels soft and voluminous and not too caused by friction irritation of the skin leads.

Accordingly, there has been found a cover and transfer layer structure for a sanitary article comprising at least one nonwoven facing comprising superabsorbent fibers and multicomponent fibers made by calendering and at least one nonwoven transfer layer comprising regenerated cellulose fibers and multicomponent fibers.

The cover layer of the layer structure according to the invention, which has an upper side and an opposite lower side, can be arranged in the structure according to the invention such that the upper side is open to the outside and readily accessible, while the lower side bears against the upper side of the transfer layer. Alternatively, the top side of the cover layer itself may in turn at least partially with another layer or layer, for. B. a protective layer to be covered. Preferably, the top of the cover layer also represents the outside of an absorbent article.

Under a cover and transfer layer structure for hygiene articles in the context of the present invention should be understood in principle such structures, which consist of at least one separate cover layer and at least one separate transfer layer are formed, regardless of whether in the layer structure according to the invention can be seen macroscopically still layers after their completion.

Suitable regenerated cellulose fibers include viscose, modal, cupro, cellulose acetate and / or lyocell fibers. Viscose fibers are particularly preferred.

Regenerated cellulose fibers are obtained like natural cellulose fibers from so-called wood fiber pulp. Regenerated cellulose fibers and their preparation are well known to those skilled in the art and readily available commercially. Lyocell fibers are regenerated cellulose fibers which are particularly environmentally friendly to produce. These fibers are obtained by extrusion of cellulose dissolved in an aqueous tertiary amine N-oxide, for example N-methylmorpholine N-oxide, into an aqueous coagulation bath by the solvent spinning process. For further details regarding the production process of lyocell fibers, see US 5,094,690. Lyocell fibers are more similar in their property profile to cotton fibers than rayon fibers. They are characterized in particular by a high strength in the wet state. Lyocell fibers may e.g. from the company Acordis Cellulosic Fiber under the trade name Tencel or the company Lenzing Fibers under the trade name Lenzing Lyocell.

Suitable multicomponent fibers include, for. B. bi- and tricomponent fibers. By bicomponent fibers are generally understood such fibers in which two different polymers in non-homogeneous form coexist. This may mean in one embodiment that two polymers are arranged side by side in a fiber strand side by side. In a further embodiment, a first polymer may form the core which is enveloped by a second polymer. In addition, it is possible for a first polymer to be completely enveloped by a second polymer to form single islands in the second polymer. Suitable bicomponent fibers are generally composed of two thermoplastic polymers, for example polyolefins and polyamides, polyolefins and polyesters or polyamides and polyesters. Particularly suitable for the present fiber webs z. B. bicomponent fiber based on polyols and polyesters, in particular comprising the combination of polyethylene / polyethylene terephthalate and polypropylene / polyethylene terephthalate. Further, in another embodiment, the bicomponent fibers comprise a polyethylene / polypropylene fiber, a polypropylene / polyethylene terephthalate fiber, a polyethylene / polyethylene terephthalate fiber, a polyethylene terephthalate / co-polyethylene terephthalate fiber, and any mixture thereof. Bi-component fibers based on polyethylene and polypropylene are particularly preferred. In this case, the polypropylene preferably forms the core of this bicomponent fiber.

Furthermore, in the present case so-called "spiral crimp" fibers are to be subsumed under suitable bicomponent fibers. "Spiral crimp" fibers are generally obtained by using a thermoplastic polymer which is used in two different viscosities. Exemplary are the "spiral crimp" polyester fibers HI 8Y from Unitika Ltd., Japan, and 7-HCS from Sum Yang, South Korea. The different viscosities of the polyester polymers used here generally go back to the use of polyesters having different molecular weights. Spiral crimp fibers regularly feature a helical configuration. For further details on "spiral crimp" fibers, see US 5,723,215.

The cover layer of the layer structure according to the invention is obtained by means of calendering. Here, the preferably homogeneously blended, the cover layer forming fibers are passed through the rollers of a calendering machine, wherein preferably at least one of the rollers is heated. During passage through the calendering machine, the fibrous material is preferably exposed to both pressure and heat. The particularly homogeneously mixed, the transfer layer forming fibers are processed using the air-through-bonding technique into a fiber web. In this case, the fiber mixture is treated in a controlled manner with a stream of heated air, so that at least some fibers of the multicomponent fiber at least partially melt on their surface and connect to adjacent fibers on cooling. In general, it already suffices if the fibrous web to be bonded is subjected to the heated air for about 5 to 10 seconds. The air temperature should preferably be chosen such that at least partially soften the outer regions of the multicomponent fibers. In addition to the multicomponent fibers, it is also possible to use thermoplastic powders or granules for bond formation or solidification. These powders and granules are preferably uniformly distributed in the nonwoven material.

In a further embodiment, it is provided that at least one nonwoven cover layer and / or at least one nonwoven transfer layer further comprise natural fibers and / or synthetic fibers.

Suitable natural fibers include, for. As cotton, wool, silk, linen, sisal, hemp, flax, ramie and jute fibers and any mixtures thereof.

As synthetic fibers, e.g. Fibers based on polyolefins such as polyethylene and polypropylene, polyamides, polyacetals, e.g. As polyoxymethylene, polyesters, such as polyethylene terephthalate and polybutylene terephthalate, polyacrylates or polymethacrylates, such as polymethyl methacrylate, into consideration. Furthermore, aramid fibers, acrylic fibers or polyvinyl alcohol fibers can be used as synthetic fibers.

Laminated structures according to the invention have proved to be particularly advantageous in which the nonwoven covering layer (s) contains about 60 to 99% by weight, in particular 88 to 96% by weight, of multicomponent fibers, natural fibers and / or synthetic fibers and 1 to 40 Wt .-%, in particular 4 to 12 wt .-%, of superabsorbent fibers comprises or comprise, in each case based on the total weight of the nonwoven cover layer (s).

Already by using only small amounts of superabsorbent fibers in the top layer, it is possible to ensure a particularly good wearing comfort, even with continuous use. When combined with multicomponent fibers, the top layer is characterized by superior softness and particularly good gliding properties on the skin. Even under heavy use, e.g. during exercise, wearing an already wetted with body fluid absorbent article containing the layer structure according to the invention, not disturbing. Irritations of the skin do not occur. Rather, the surface of the layer structure according to the invention slides in a fluid wetted and unwetted state soft and gentle to the skin over the adjacent or pressed skin.

Particularly satisfactory results are obtained with layer structures according to the invention, in which the multicomponent fiber comprises a bicomponent fiber, in particular a PP / PE bicomponent fiber.

In this case, preference is given to those layer structures which are characterized in that the bicomponent fiber of the nonwoven transfer layer has at least one eccentric bicomponent fiber, in particular an eccentric PP / PE bicomponent fiber. Particularly good fluid acquisition properties are achieved with the abovementioned layer structures.

It can be provided that the nonwoven covering layer has a basis weight in the range of about 5 to 45 g / m ² , in particular in the range of about 10 to 35 g / m ² has.

Furthermore, it can be provided that the nonwoven transfer layer has a basis weight in the range from about 5 to 80 g / m ² , in particular in the range from about 10 to 40 g / m ² . According to another aspect of the present invention, there is provided an absorbent article comprising at least one layered structure according to any one of the preceding claims, at least one absorbent core, in particular adjacent to the nonwoven transfer layer of the layered structure, and optionally at least one substantially fluid-impermeable barrier layer facing that side of the layer facing absorbent core, which is opposite to the layer structure includes.

Suitable absorbent articles provide z. As sanitary napkins, panty liners, diapers, incontinence protection articles, wound dressing materials and wipes. Furthermore, it is also possible to equip tampons with the layer structure according to the invention.

The object underlying the invention is further achieved by a method for producing a laminated cover and transfer layer structure for hygiene articles, comprising the steps:

a) producing at least one nonwoven fabric for at least one cover layer comprising a top and an opposite underside of superabsorbent fibers and multicomponent fibers by means of calendering,

b) producing at least one nonwoven fabric for at least one transfer layer, comprising a top and an opposite underside, made of regenerated cellulose fibers and multicomponent fibers by means of air-through-bonding technique, and

c) forming a laminate of cover layer and transfer layer of the nonwovens of cover and transfer layer, wherein the underside of the cover layer and the top of the transfer layer are adjacent to each other. The laminate of cover layer and transfer layer can advantageously be obtained by means of thermobonding, in particular calendering and / or through-air bonding, water jet needling and / or needle punching. The through-air-bonding technique is particularly preferred and provides particularly airy, lightweight products.

With the layer structure according to the invention, it is possible surprisingly to obtain absorbent hygiene articles whose surfaces feel soft and voluminous even after wetting with a body fluid and which can be displaced on the skin without or with only a very low frictional resistance. Furthermore, even after multiple wetting of the cover layer of the layer structure according to the invention, body fluids easily pass through them without being impeded by superabsorbent fiber dressings which are already loaded with fluid. Even larger amounts of fluid occur within a very short time, z. B. within only about 15 seconds, through the layer structure according to the invention.

In the following, by way of example with reference to a specific layer structure according to the invention, its absorption and retention capacity are shown.

The layer structure according to the invention comprised a nonwoven covering layer of 95% by weight of bicomponent fibers from FiberVisions (ES-Cure, 2.2 dtex) and 5% by weight of superabsorbent fibers from Oasis (Superabsorbent Fibers 102), prepared by means of calendering, as well as a fiber fleece transfer layer of 67% by weight of a bicomponent fiber from FiberVisions (ES Superbulk, 3.3 dtex) and 33% by weight of viscose fibers from Lenzing (1.7 dtex). While the top layer had a basis weight of 15 g / m ² , the transfer layer had a basis weight of 40 g / m ² .

For comparison, the absorption and retention capacity of a layer structure comprising a cover layer containing thermobonded polypropylene fibers, and a transfer layer prepared by the air-through-bonding technique, containing 70% by weight of bicomponent fibers and 30% by weight of PET fibers.

The absorbency of the laminate structure in the form of a sanitary napkin was tested by dropping 7 ml of aqueous test liquid to a location on the topcoat such that each drop penetrated and was absorbed into the laminate structure. The time between the onset of the first liquid drop and the complete absorption of the last liquid drop was determined.

The retention capacity of this laminate structure was determined by covering the above-described liquid-soaked product with ten layers of filter paper MN 615 (Macherey and Nagel) and weighing for three minutes with a weight of 5 kg. The difference between the weight of the filter paper in the dry state and after three minutes of contact with the test fluid-containing laminate structure was determined as a measure of their retention capacity.

The absorption time of the comparison structure, determined by the method described above, was about 11 seconds, that of the structure according to the invention about 20 seconds. For the retention capacity determined by the above method, a value of 0.9 g was determined for the comparative structure and 1.1 g for the structure according to the invention. With regard to absorption and retention capacity, the layer structure according to the invention is thus to be regarded as equivalent to conventional layer structures, but still feels soft and voluminous, and does not cause any irritation, even after prolonged use after the fluid has been wetted, in contrast to conventional top and transfer layer structures Skin due to friction. The features of the invention disclosed in the foregoing description and in the claims may be essential both individually and in any combination for the realization of the invention in its various embodiments.

Claims

claims

A cover and transfer layer structure for a sanitary article comprising at least one nonwoven facing comprising superabsorbent fibers and multicomponent fibers made by calendering and at least one nonwoven transfer layer comprising regenerated cellulose fibers and multicomponent fibers.

2. Layer structure according to claim 1, characterized in that at least one nonwoven cover layer and / or at least one nonwoven transfer layer further comprise natural fibers and / or synthetic fibers.

3. Layer structure according to claim 1 or 2, characterized in that the nonwoven covering layer (s) about 60 to 99 wt .-%, in particular 88 to 96 wt .-%, of multi-component fibers, natural fibers and / or synthetic fibers and 1 to 40 Wt .-%, in particular 4 to 12 wt .-%, of superabsorbent fibers comprises or comprise, in each case based on the total weight of the nonwoven cover layer (s).

4. Layer structure according to one of the preceding claims, characterized in that the multi-component fiber comprises a bicomponent fiber.

5. Layer structure according to claim 4, characterized in that the bicomponent fiber of the fiber transfer layer comprises at least one eccentric bicomponent fiber.

6. Layer structure according to one of the preceding claims, characterized in that the fiber based on regenerated cellulose comprises viscose fibers.

7. Layer structure according to one of the preceding claims, characterized in that the nonwoven cover layer has a basis weight in the range of about 5 to 45 g / m ² , in particular in the range of about 10 to 30 g / m ² comprises.

8. Layer structure according to one of the preceding claims, characterized in that the nonwoven transfer layer has a basis weight in the range of about 5 to 80 g / m ² , in particular in the range of about 10 to 40 g / m ² .

Absorbent article comprising at least one layered structure according to one of the preceding claims, at least one absorbent core, in particular adjacent to the fiber transfer layer of the layered structure, and optionally at least one substantially fluid-impermeable barrier layer facing that side of the absorbent core which faces the absorbent core Layer structure opposite.

Absorbent article according to claim 9, characterized in that it comprises a sanitary napkin, a panty liner, a diaper, an incontinence guard, a wound dressing, a wipe and a tampon.

11. A method for producing a laminated cover and transfer layer structure for hygiene articles, in particular according to one of claims 1 to 8, comprising the steps: a) producing at least one nonwoven fabric for at least one cover layer comprising a top and an opposite underside of superabsorbent fibers and multicomponent fibers by means of calendering,

c) forming a laminate of cover layer and transfer layer of the nonwovens of cover and transfer layer, wherein the underside of the cover layer and the top of the transfer layer are adjacent to each other.

12. The method according to claim 11, characterized in that the laminate of cover layer and transfer layer by means of thermobonding, in particular calendering and / or through-air bonding, water jet needling and / or mechanical needling (needle punching) is produced.