WO2008018921A1

WO2008018921A1 - Absorbent product with unitized gradient core

Info

Publication number: WO2008018921A1
Application number: PCT/US2007/006863
Authority: WO
Inventors: John D. Litvay
Original assignee: Litvay John D
Priority date: 2006-08-04
Filing date: 2007-03-20
Publication date: 2008-02-14

Abstract

The present invention provides an absorbent product, such as disposable diapers, incontinent pads, sanitary napkins that has an absorbent core that comprises recycled synthetic material. The core is produced from the waste created in the manufacturing process of previously produced absorbent products.

Description

ABSORBENT PRODUCT WITH UNITIZED GRADIENT CORE

BACKGROUND OF INVENTION Absorbent products, such as baby diapers have a 90 to 95% market penetration in the United

States and Europe. The levels of market penetration in some of the emerging market countries such as China and India are less than 5 %. Part of the reason for this low level of penetration is the relative high cost of these products in those markets.

Manufacturers of absorbent products in the emerging market countries face an enormous challenge in trying to find ways to produce lower cost products. The cost of raw materials comprise up to seventy to eighty percent of the cost to manufacture such products, hi order to produce a functional absorbent product a minimum amount of conventional materials need to be employed. If a manufacturer reduces the amount of material used beyond this minimum, the functionality of the product is greatly diminished. Absorbent products such as baby diapers, feminine hygiene pads and adult incontinent products are typically constructed of several different types of materials. These products typically consist of a permeable non-woven top sheet, transfer layer, an impermeable back sheet and an absorbent core sandwiched between the back sheet and transfer layer. The absorbent core typically consists of wood fluff and a water-absorbing polymer, which is prepared from monomers of acrylic acid.

Given that 70% to 80% of the product costs are associated with the materials used, any component that can be eliminated would lower overall costs. Typically, conventional diapers have what are called transfer or acquisition layers for the purpose of wicking away any liquid exudates from the top layer into the absorbent core, which is wood fluff. Costs to producers in the developing world are even higher due to the fact that most producers of this component are in western countries. The cost associated with this material includes transportation and handling. Eliminating this component would be a significant savings to manufacturers.

Accordingly, there is a need in the art for novel approaches to recycle waste that is generated during the production of absorbent products. SUMMARY OF INVENTION

The present invention provides an absorbent product, such as disposable diapers, incontinent pads, sanitary napkins that has an unitized absorbent core that incorporates an acquisition or transfer layer eliminating the need for a separate component for the same purpose. The unitized core has a synthetic fiber matrix that is of a high or low denier on the portion closest to the top sheet and a lower or higher denier on the portion that is closest to the back sheet.

In accordance with another aspect the present invention the unitized absorbent core is produced out of absorbent garment waste materials.

The above and other aspects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 illustrates a top view of a conventional diaper showing the absorbent synthetic core.

Figure 2 illustrates a cross-sectional view of the absorbent core showing the unitized synthetic fibers, wherein the upper portion has a high denier fiber and the lower portion has a lower denier fiber creating a gradient in the X direction.

Figure 3 illustrates a top plan view of a spinneret that could be used to create the unitized absorbent core with the synthetic fiber gradient.

DETAILED DESCRIPTION OF INVENTION

The invention relates to the manufacture and use of an absorbent core, which comprises a unitized synthetic fiber. The absorbent core has a unitized synthetic fiber which creates a matrix has a high denier fiber on the portion closest to the top sheet and a lower denier fiber on the portion that is closest to the back sheet.

The types of absorbent products that can be produced include disposable diapers, incontinent pads; sanitary napkins wherein the absorbent core comprises recycled synthetic materials.

FIGURE 1 is a plan view of a conventional diaper in its uncontracted state with the center oval area showing the absorbent core 10 and diaper chassis 20 leg cut out 30 which consists of compatible material, which can be recycled to produce the unitized synthetic fiber of the present invention. Typical diaper construction consists of a liquid pervious top sheet, a liquid impermeable back sheet and an absorbent core sandwiched there between. It is understood that a variety of absorbent garment constructions know in the art could incorporate the absorbent core of the present invention. FIGURE 2 shows a cross-section of an absorbent product incorporating an absorbent core with an upper portion 31 that has low denier fiber and a lower portion 32, which has higher denier fiber. It is understood that this can be switched to have the high denier fiber on the upper portion and the lower on the lower portion. The unitized core creates a gradient, which eliminates the need for a separate acquisition or transfer layer component. Figure 3 illustrates a spinneret with large openings in the upper portion and smaller openings in the lower portion. This spinneret allows for the extrusion of the unitized synthetic fiber of the present invention. As can be appreciated, the basic concept for making this new fiber is to provide small openings for the lower denier fiber (lower portion) and openings that are larger for the high denier fiber (upper portion). Such opening can take many shapes. Preferably, those shapes would create fibers that would facilitate the wicking of liquid.

The absorbent core, which comprises the unitized synthetic fibers of the present invention, can be produced by various tow extrusion methods. For example methods disclosed in US Patent

Nos. 3,081,519, 3,165,563, 3,242,035 and 4,054,550, can be used. These patents are incorporated herein in a manner consistent with the present invention. These extrusion methods require the spinneret modification as explained herein and illustrated in Figure 3.

The "top sheet" of the present invention can be any permeable polymeric plastic non-woven sheet known in the state of the art. A suitable top sheet may be made from apertured plastic films, polyolefin fibers (e.g. polyethylene or polypropylene fibers) or combinations thereof. The "absorbent core" can be any synthetic material known in the state of the art that can be made into tow. Such materials include synthetic materials such as polyolefins. Polyolefins include polypropylene and polyethylene.

The super absorbent particulate of the present invention can be any conventional water- swellable material such as synthetic hydrogel polymer. These include polyacrylic acids.

The "back sheet" of the present invention can be any impermeable polymeric plastic and/or non-woven sheet known in the state of the art. A suitable back sheet may be made from films polyethylene and polypropylene and blends of these materials.

While particular embodiments and/or individual features of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Further, it should be apparent that all combinations of such embodiments and features are possible and can result in preferred executions of the invention. Therefore, the appended claims are intended to cover all such changes and modifications that are within the scope of the invention.

Claims

CLAIMS I claim:

1. An absorbent garment comprising: a. a liquid permeable top sheet; b. a liquid impermeable back sheet; and c. an absorbent core positioned there between comprising: i. unitized continuous synthetic fibers; and ii. super absorbent particulate where the unitized synthetic fiber has an upper portion with low denier fiber and a lower portion with higher denier fiber.

2. The absorbent garment of claim 1 , wherein the unitized continuous fiber is a polyolefin.

3. The absorbent garment of claim 1, wherein the absorbent core further includes a non-woven wrap.

4. The absorbent garment of claim 1, wherein the absorbent garment further includes leg cuffs positioned on top of the top sheet.

5. The absorbent garment of claim 7, wherein the absorbent garment further includes leg cuffs positioned on top of the top sheet.

6. A method of manufacturing an absorbent garment comprising: a. manufacturing an absorbent garment comprising: i. a liquid permeable top sheet; ii. a liquid impermeable back sheet; iii. an absorbent core positioned there between comprising, a unitzed continuous synthetic fiber and a super absorbent particulate, b. collecting waste consisting of compatible material from the first manufacturing step; c. shredding the collected waste; d. forming the shredded compatible waste into pellets; e. melting the formed pellets; and f. extruding the melted pellets into recycled continuous synthetic fiber, wherein the recycled continuous synthetic fiber is in used to produce the absorbent core.

7. A method of manufacturing an absorbent garment comprising: a. manufacturing an absorbent garment comprising: i. a liquid permeable top sheet; ii. a liquid impermeable back sheet; iii. an absorbent core positioned there between comprising, a recycled continuous synthetic fiber and super absorbent, b. collecting waste consisting of compatible and incompatible material from the manufacturing step; c. shredding the waste; d. separating the compatible from the incompatible waste; e. forming the separated shredded compatible waste into pellets; f. melting the pellets; and g. extruding the melted pellets into recycled continuous synthetic fiber.

8. An absorbent garment comprising: a. a liquid permeable top sheet; b. a liquid impermeable back sheet; and c. an absorbent core positioned there between comprising: i. unitized continuous synthetic fibers; and ii. super absorbent particulate where the unitized synthetic fiber has an upper portion with high denier fiber and a lower portion with lower denier fiber.

9. The absorbent garment of claim 8, wherein the unitized continuous fiber is a polyolefϊn.

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