Air-laid web with hollow synthetic fibers

Abstract

The present invention relates to a single layer air-laid composition comprising: hollow synthetic fiber, absorbent and a binder system. The hollow fiber comprises from about 10 to about 50 percent by weight of said composition. The hollow synthetic fiber has a denier of between about 2 to about 18. The hollow synthetic fiber is selected from the class of polyolefins, polyesters, polyamides, acrylics, as well as mixtures and copolymers thereof. The absorbent comprises from about 40% to about 80% of the weight of said composition. The absorbent is a natural absorbent, or a synthetic absorbent, or a mixture of these. The natural absorbent is selected from the class of wood pulp fluff, cotton, cotton linters, and regenerated cellulose fibers, or a mixture of these. The synthetic absorbent is selected from the class of agar, pectin, guar gum, and synthetic hydrogel polymers. The binder fiber comprises from about 3 to about 15 percent by weight of said composition.

Description

[0001] This application is a continuation-in-part of U.S. Ser. No. 10 / 345,001 filed Jan. 15, 2003 in the name of Mabrouk Ouedemi, which was itself a continuation-in-part of U.S. Ser. No. 09 / 896,799 filed Jun. 29, 2001.[0002] 1) Field of the Invention[0003] The present invention relates to a single layer air-laid composition useful as an absorbent core in diapers, incontinent pads, sanitary napkins and other absorbent pads needed for body fluids. In particular, the present invention comprises a composition of an absorbent comprising wood pulp and optionally a super absorbent polymer, a binder system, and up to 50% hollow synthetic fibers based on the total composition weight. The composition of the present invention has an improved loft, compression resistance and fluid intake rate superior to existing composites based on natural absorbents and non-hollow synthetic fibers.[0004] Diapers, incontinent pads, sanitary napkins, and other absorbent pads used for uptaking bodily fluids gene...

AI Technical Summary

Benefits of technology

[0014] The present invention relates to an air-laid composition comprising absorbent, binder, and hollow synthetic fibers. If the binder system is based on binder fibers, it is desired to maintain the percentage of binder at about 10% by weight as it has been determined that this amount of binder is sufficient to adequately bind the web into a unitary structure. On the other hand, the hollow fiber can comprise from about 10% up to about 50% by weight of the composition. This means that the absorbent comprise from 40% to 80% by weight of the composition. Replacing the solid synthetic fibers with synthetic hollow fibers surprisingly increases the loft, and the fluid intake rate, as well as the compression resistance.

[0016] Air-laid composites of the present invention provide good compression resistance, loft, and fluid intake increase as compared with a composite based on bicomponent fibers, wood pulp fibers, and solid synthetic fibers. To increase the absorbency of the web of the present invention, some of the wood pulp may be replaced with SAP.

[0020] Suitable absorbents are natural or synthetic absorbents. Synthetic absorbents are primarily known as super absorbent polymers (SAP). The absorbents comprise 40-80% by weight of the absorbent core. Natural absorbents are hydrophilic materials such as cellulosic fibers, wood pulp fluff, cotton, cotton linters, and regenerated cellulose fibers such as rayon, or a mixture of these. Preferred is wood pulp fiber, which is both inexpensive and readily available.

[0021] Conventional natural absorbents do not absorb as much bodily fluid as when a portion of them has been replaced with synthetic fibers, and preferably polyester fibers, which provide loft to the composite. Providing loft to the composite exposes more surface area of the natural absorbents to the bodily fluids and thus the natural absorbents are much more efficient in absorbing the bodily fluid, compared to absorbent cores having little or no loft, but more absorbent material.

[0022] Absorbent cores employing natural absorbents may not provide adequate fluid intake for all circumstances. Also natural absorbents are very bulky. Accordingly, many absorbent pads employ SAP in relatively low quantities because the cost of SAP is much higher than the cost of natural absorbents. Replacing some of the natural absorbents with SAP can reduce the overall bulk of the pad and / or provide superior fluid intake.

[0024] The synthetic hollow fibers improve the loft of the composite compared to a composite having solid synthetic fibers. These fibers typically have a denier of about 2 to about 18. Generally, the fibers are between 3 and 20 mm in length and preferably from about 4 to 12 mm in length. Preferably all the fibers are hollow. However a portion of them can be replaced with any other solid polymeric fibers. The synthetic hollow fibers comprise 10-50% by weight of the web. The web composition (absorbent core) of the present invention has weights in the range of about 50 to about 500 grams per square meter (gsm).

Problems solved by technology

The problem that Ito sought to solve was leakage due to an insufficient absorbing capacity in the first absorbing layer.

The fabric is a multilayer layer composition that can be used as a top sheet in a diaper, but it does not teach the use of hollow fibers in an absorbent core.

Additionally, the bulky layer of Barge is formed by a carding process.

There is no teaching on the use of air forming with wood pulp, hollow and binder fibers.

These types of chemical bonding can coat the wood pulp fibers decreasing their absorbency.

Absorbent cores employing natural absorbents may not provide adequate fluid intake for all circumstances.

Also natural absorbents are very bulky.

Accordingly, many absorbent pads employ SAP in relatively low quantities because the cost of SAP is much higher than the cost of natural absorbents.