WO2008115182A1

WO2008115182A1 - Absorbent product with high performance profile

Info

Publication number: WO2008115182A1
Application number: PCT/US2007/006867
Authority: WO
Inventors: John D. Litvay
Original assignee: Litvay John D
Priority date: 2007-03-20
Filing date: 2007-03-20
Publication date: 2008-09-25

Abstract

The present invention provides an absorbent garment, such as disposable diapers or adult briefs that have a synthetic absorbent core that provides superior performance. It was unexpectedly discovered that the combination of an apertured polyolefin acquisition layer and a synthetic core matrix containing SAP with a high Centrifuge Retention Capacity (CRC) had superior performance when compared to absorbent garments with wood fluff matrix absorbent cores. The superior performance was measured in terms of rewets, total capacity and acquisition time.

Description

ABSORBENT PRODUCT WITH HIGH PERFORMANCE PROFELE

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 low cost products. The cost of raw materials comprise up to seventy to eighty percent of the cost to manufacture such products. In 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, an impermeable back sheet and an absorbent core sandwiched there between. The absorbent core typically consists of wood fluff and a water- absorbing polymer, which is prepared from monomers of acrylic acid. This water-absorbing polymer referred to, as Super Absorbent Polymer or SAP, can constitute 20% to 30 % of the material cost of the product. In addition, as of the date of the present writing, there is a worldwide shortage of SAP driving costs even higher. In addition, wood fluff can cost an addition 10 — 20% of the material cost of the product.

Given that 70% to 80% of the product costs are associated with the materials used. Any lower cost material that can be incorporated into such products would enable the manufacturer to lower costs to the end user.

Accordingly, there is a need in the art for a cost effective absorbent garment with performance characteristics that are superior or comparable to products that are currently commercially available. SUMMARY OF INVENTION

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 garment showing the top sheet, acquisition layer, synthetic fibers (with SAP) and back sheet.

DETAILED DESCRIPTION OF INVENTION

The invention relates to absorbent garments with superior performance characteristics. The types of absorbent products that can be produced include disposable diapers, incontinent pads, sanitary napkins wherein the absorbent core comprises synthetic fibers and super absorbent paniculate with high Centrifugal Retention Capacity and an apertured polyolefin film acquisition layer.

FIGURE 1 is a plan view of a conventional diaper in its uncontracted state with the center oval area showing the absorbent core 102 and diaper chassis 101. Typical diaper construction consists of a 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 and acquisition layer of the present invention.

FIGURE 2 shows a cut away cross-section of the absorbent garment of the present invention with absorbent core 103 (containing high CRC SAP), apertured polyolefin acquisition layer 104, top sheet 105 and back sheet 106. 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. It is understood that additional layers may be present between the absorbent core and the top sheet.

The "absorbent core" matrix 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, rayon, polycarbonates and cellulose acetate. Polyolefins include polypropylene and polyethylene.

Super absorbent polymer or particulate (SAP) is typically tested for various parameters such as Centrifuge Retention Capacity (CRC), Absorption Against Pressure (or Absorption Under Load), moisture content, apparent specific gravity and particle size distribution. Suitable SAP of the present invention have high CRC in the range of about 35 to 55. It is the belief of those with skill in the art that such high CRC SAPs are not suitable for high liquid capacity products such as baby diapers. While this is true of diapers with wood fluff matrix cores, we have discovered that this is not true for diapers with cores with a synthetic matrix. Currently high CRC SAPs are only used in low liquid capacity products such as feminine hygiene products. Partly because of this another advantage of the high CRC SAPs of the present invention is that they tend to be less expensive than the lower CRC rated SAPS (those with CRC of 30 and below).

The "acquisition layer" suitable for the present invention includes apertured polyolefin films. While the acquisition layer tested was polypropylene it is believed that other polyolefin

4 materials may be suitable such as polyethylene. In addition, while gsms of 29 and 39 were tested, it is believed that other materials with a gsm in the same range would also be suitable.

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, polypropylene, polyester, nylon, and polyvinyl chloride and blends of these materials.

It is understood that additional layers may be present between the absorbent core and the back sheet.

The first absorbent garment ("1^st Test") tested comprised an apertured polyolefin film with a grams per square meter (gsm) of 39 (purchased from Tredegar, Italy). The acquisition layer ran the full length of the absorbent core. The absorbent core contained a SAP with a Centrifuge Retention Capacity (CRC) of about 37 (purchased from Sumitomo, Japan).

The second absorbent garment ("2^nd Test") tested comprised an apertured polyolefin film with a gsm of 39 (purchased from Tredegar, Italy), which ran the full length of the absorbent core. The absorbent core synthetic matrix contained SAP with a CRC of about 38 (purchased from Sanwong, South Korea). The third absorbent garment ("3^rd Test") tested comprised an apertured polyolefin film with a gsm of 39 (purchased from Tredegar, Italy), which ran the full length of the absorbent core. The absorbent core contained a SAP with a CRC of about 41 (purchased from Kolon Chemical Company, South Korea).

The fourth absorbent garment ("4^th Test") of the present invention tested comprised an apertured polyolefin film with a gsm of 39 (purchased from Tredegar) which ran a distance short of the complete length of the absorbent core. The absorbent core contained SAP with a CRC of about 30 (purchased from BASF, Germany).

The fifth absorbent garment ("5^th Test") of the present invention tested comprised an apertured polyolefin film (purchased, from Tredegar, Italy) with a gsm of 29 which ran the entire distance of the absorbent core. The absorbent core contained SAP with a CRC of about 30

(purchased from BASF, Germany). This test product was not tested for total capacity since the same SAP was tested in the fourth test product.

The sixth absorbent garment ("6^th Test") of the present invention tested comprised a non- woven acquisition layer (purchased from IDEVCO, Saudi Arabia) which ran the entire distance of the absorbent core. The absorbent core contained SAP with a CRC of about 30 (purchased from BASF, Germany). This test product was not tested for total capacity since the same SAP was tested in the fourth test product. The six test products mentioned above were all tested for a "third rewet" (experimental protocol as described herein) and liquid acquisition time (experimental protocol as described herein). The four products (test products 1-4) with the four different SAPs with varying CRCs were used to determine their total capacity (experimental protocol as described herein). Test products 4 through 6 used the same SAP so only "4^th Test" product was measured for total capacity.

Three insult Experimental Protocol:

1. diaper was laid open absorbent core facing up;

2. SO mis of 1.0% saline solution was applied to the center of the absorbent core; 3. after 60 minutes a second SO mis of 1.0% saline solution was applied to the center of the absorbent core (same area);

4. after 60 minutes a third 50 mis of 1.0% saline solution was applied to the absorbent core;

5. at 60 minute time a blotter towel was applied to the insult area under a 300 g weight for 30 seconds; and 6. the blotter towel was then removed and weighed.

The 3 insult results are compiled in Table 1 below.

Table 1

Total Capacity Protocol

1. each diaper sample was submerged in a bucket of 1 % saline solution for 60 minutes;

2. each diaper was then removed and was hung to remove excess liquid for 30 minutes;

3. the diapers were then placed into a centrifuge for 10 minutes; and

4. the diapers were weighed (subtracting the diapers dry weight).

The total capacity results are compiled in Table 2 below.

Table 2

Acquisition Time Protocol

1. the test products were laid open with absorbent core facing up;

2. 50 mis of 1% saline solution were applied to the center of the absorbent core; 3. once the SO mis were applied, a stop watch was started and the complete adsorption of the liquid was timed. The acquisition time results were compiled in Table 3 below.

Table 3

The above criteria were established for 3 commercial products with wood fluff matrix cores. The first commercial product (1^st Fluff) was product branded "Pampers" (produced by P&G, Saudia Arabia). The second commercial product (2^nd Fluff) tested was a product branded "Lido" (produced by AldaliyaTrading, United Arab Emirates). The third tested product (3^rd Fluff) was branded "Bambi" (produced by INDEVCO, United Arab Emirates).

The results are compiled in Table 4 below. Table 4

What was discovered was that the higher CRC SAPs in combination with an apertured polyolefin film acquisition layer, had superior performance characteristics when measuring at "3^rd Rewet", 'Total Capacity" and "Acquisition Time".

The aforementioned embodiments and examples are meant to be just for explanatory purposes and are in no way meant to be limiting. Various other configurations are possible within the spirit of the invention. The invention intends to cover all such embodiments within the boundaries defined by the appended claims.

Claims

CLAIMS I claim:

1. An absorbent product comprising: a. a liquid permeable top sheet; b. an absorbent core comprising: i. synthetic fibers; ii. super absorbent particulate; c. an apertured polyolefin film acquisition layer positioned between the top sheet and the absorbent core; and d. a back sheet wherein the super absorbent particulate has a CRC in the range of about 35 to 45.

2. The absorbent product of claim 1, wherein the synthetic fibers are selected form the group consisting of rayon, polypropylene, cellulose acetate or polyethylene.

3. The absorbent product of claim 1, wherein the super absorbent particulate has a CRC value of about 41.

4. The absorbent product of claim 1 , wherein the acquisition layer has a gsm in the range of about 25 to 45.

5. The absorbent product of claim 1 , wherein the acquisition layer has a gsm of about 29.

6. The absorbent product of claim 1, wherein the acquisition layer has a gsm of about 39.

7. The absorbent product of claim 1 , wherein the acquisition layer is polypropylene.

8. An absorbent product comprising: a. a liquid permeable top sheet; b. an absorbent core comprising:

9 i. synthetic fibers; ii. super absorbent particulate; c. an apertured polyolefin film acquisition layer positioned between the top sheet and the absorbent core; and d. a back sheet

. wherein the super absorbent particulate has a CRC in the range of about 35 to 45 and the acquisition layer has a gsm in the range of about 25 to 45.

9. The absorbent product of claim 8, wherein the synthetic fibers are selected form the group consisting of rayon, polypropylene, cellulose acetate or polyethylene.

10. The absorbent product of claim 8, wherein the super absorbent paniculate has a CRC value of about 41.

11. The absorbent product of claim 8, wherein the acquisition layer has a gsm in the range of about 29.

12. An absorbent product comprising: a. a liquid permeable top sheet; b. an absorbent core comprising: i. synthetic fibers; ii. super absorbent particulate; c. an apertured polyolefin film acquisition layer positioned between the top sheet and the absorbent core; and d. a back sheet wherein the super absorbent particulate has a CRC of about 40 and an acquisition layer with a gsm in the range of about 25 to 45.

13. The absorbent product of claim 12, wherein the synthetic fibers are selected form the group consisting of rayon, polypropylene, cellulose acetate or polyethylene.

14. The absorbent product of claim 12, wherein the acquisition layer is polypropylene.

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