Absorbent article with improved fluid acquisition system

Details Absorbent article with improved fluid acquisition system Absorbent article with improved fluid acquisition system

1999-11-12

2002-09-24

Ruhl, Dennis (Department: 3761)

Surgery

Means and methods for collecting body fluids or waste material

Absorbent pad for external or internal application and...

C604S378000, C604S368000, C604S374000

Reexamination Certificate

active

06455753

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to disposable absorbent articles and more specifically to disposable absorbent articles, e.g., diapers, which exhibit enhanced liquid absorption and trapping characteristics.
BACKGROUND OF THE INVENTION
Disposable absorbent articles, e.g., diapers, catamenial pads, panty liners, shields, etc., frequently make use of a liquid absorbent core located between a top-sheet and a back sheet. The top-sheet is commonly formed of a material which is pervious to body fluids, e.g., urine, to promote the transfer of such fluids into the core with minimal fluid retention by the top-sheet. The back-sheet is commonly formed of a liquid impervious or hydrophobic material to form a barrier wall so that any fluid absorbed by the article cannot escape out the back-sheet. In many cases, a fluid “acquisition,” “surge” or “transfer” layer is located between the top-sheet and the core to facilitate the transference of body fluid(s) into the core.
In some applications the top-sheet of the disposable absorbent article is formed a woven, non-woven or carded fibrous web. In other cases a perforated or apertured polymeric film is used in place of the fibrous web top-sheet. Typically most of such apertured films are of a three dimensional nature, e.g., they are embossed and/or debossed to include numerous protuberances, channels, capillaries, hills and valleys, etc. Such three dimensional apertured film top-sheets exhibit a pleasing soft, cloth-like appearance similar to that of the prior art woven, non-woven or carded fibrous webs, while providing for a quick and efficient transfer of liquid therethrough to the underlying absorbent layer(s).
Examples of perforated three dimensional film top-sheets are found in U.S. Pat. No. 3,929,135 (Thompson), U.S. Pat. No. 4,324,246 (Mullane et al.), U.S. Pat. No. 4,327,730 (Sorensen), U.S. Pat. No. 4,463,045 (Ahr et al), U.S. Pat. No. 4,552,709 (Koger et al.), U.S. Pat. No. 4,601,868 (Radel), U.S. Pat. No. 4,609,518 (Curro et al.), U.S. Pat. No. 4,629,643 (Curro et al.), U.S. Pat. No. 4,690,679 (Mattingly, III et al.), U.S. Pat. No. 4,806,411 (Mattingly, III et al.), U.S. Pat. No. 5,514,105 (Goodman et al.), U.S. Pat. No. D362,120 (Suskind et al), and U.S. Pat. No. D364,040 (Suskind), and in United States Statutory Invention Registration H1575 (Daugherty et al.).
The absorbent core of many disposable diapers and other higher performance incontinence products, e.g., adult briefs, typically have cores with enhanced absorbency capability. This enhanced absorbency can be accomplished by use of an air-laid super absorbent material, or by the inclusion of absorbency enhancers, e.g., materials sometimes referred to as “super-absorbent-polymers” (which may be in the form of particles or fibers) with other absorbent materials, such as a fluff, e.g., comminuted wood pulp or other cellulosic fibers. Examples of super absorbent materials are hydrogel polymer particulates, sometimes referred to as “SAP,” and hydrogel polymer fibers, sometimes referred to as “SAF.” The fluff for the core serves as a means for quickly absorbing the liquid transferred to it. Unfortunately, while fluff is suitable for the task of quick absorption it is somewhat deficient from the standpoint of liquid retention and ability to accommodate repeated insults. SAP on the other hand, has the ability to retain absorbed liquid and to handle repeated insults. The drawback with SAP and SAF are their slowness in absorbing liquid. Accordingly, heretofore disposable absorbent articles have typically taken two approaches to ensure efficient action. In particular, they have included a higher ratio of SAP to fluff to facilitate the rapid absorption of the liquid by the fluff of the core until to SAP can absorb and trap it, and have also included an the heretofore mentioned acquisition or surge layer (also sometimes called a “transfer” layer) disposed over the core. Acquisition layers have typically been constructed of a woven, non-woven or carded fibrous material. They are arranged to quickly absorb the liquid through the absorbent article's cover stock, liner, or top-sheet for temporary retention (e.g., to act as a temporary reservoir), and to transfer that liquid into the underlying core at a rate at which the core can absorb for final or permanent retention. In particular, an acquisition layer improves “wicking” of the absorbent article by spreading the body fluid in the “x” and “y” plane over the area of the core encompassed by the acquisition layer while also carrying the fluid in the “z” direction to the core.
Examples of prior art acquisition layers are disclosed in U.S. Pat. No. 4,988,344 (Reising et al.), U.S. Pat. No. 4,994,037 (Bernardin), U.S. Pat. No. 5,294,478 (Wanek et al.), U.S. Pat. No. 5,300,054 (Feist et al.), U.S. Pat. No. 5,304,161 (Noel et al.), U.S. Pat. No. 5,387,208 (Ashton et al.), U.S. Pat. No. 5,460,622 (Dragoo et al.), U.S. Pat. No. 5,486,167 (Dragoo et al.), U.S. Pat. No. 5,520,673 (Yarbrough et al.), U.S. Pat. No. 5,522,809 (Larsonneur), U.S. Pat. No. 5,558,655 (Jezzi et al.), U.S. Pat. No. 5,591,149 (Cree et al.), U.S. Pat. No. 5,607,414 (Richards et al.), U.S. Pat. No. 5,609,588 (DiPalma et al.), U.S. Pat. No. 5,730,737 (Widlund et al.), U.S. Pat. No. 5,752,945 (Mosley et al.), U.S. Pat. No. 5,833,678 (Ashton et al.), U.S. Pat. No. 5,843,055 (Seger), U.S. Pat. No. 5,855,572 (Schmidt), U.S. Pat. No. 5,895,379 (Litchholt et al.), and U.S. Pat. No. 5,906,602 (Weber et al.). Examples of commercially available materials used for acquisition layers in disposable absorbent articles are through-air bond staple fibers, adhesively bonded staple fibers, and thermally point bonded staple fibers.
As will be appreciated by those skilled in the art increasing the SAP (or other absorption enhancing material) to fluff ratio to provide an absorbent product, e.g., diaper, suitable for accommodating multiple insults of body fluids would concomitantly place an additional burden on the liquid acquisition layer to facilitate transfer of the liquid at a rate that the SAP/other absorption enhancing material could accommodate. Heretofore the materials making up the prior art liquid acquisition layers have provided less than desired results.
Accordingly a need exists for a diaper or other high capacity absorbent article making use of a relatively high SAP/other absorption enhancing material content core and an effective liquid acquisition system to transfer the liquid into the core.
Various absorbent articles which are commercially available have made use of various layers of materials. For example, sanitary pads made by The Kendall Confab Retail Group and sold under the trademark EVERYDAY PANTILINER have included a top sheet formed of a fibrous material over the marginal edges of the pad, but not over the intake or “target” zone (i.e., the area at which the body fluid(s) gain(s) ingress into the absorbent article), a three dimensional apertured film forming the top layer of the intake/target zone, a fluid acquisition layer formed of a fibrous material (non-woven) web, and a core formed of an air laid web containing super absorbent material. Other pads in the form of Ultra Thins are also made by The Kendall Confab Retail Group and sold under trademark FRESH TIMES have included a top sheet formed of an apertured film, an air-laid acquisition layer and a core formed of a combination of air-laid and SAP or an air laid super absorbent material. Still other pads in the form of Contour Maxi pads are made by The Kendall Confab Retail Group and sold under the trademark FRESH TIMES have included a top sheet formed of an apertured film and a core formed fluff. Still other pads in the form of Maxi pads are made by The Kendall Confab Retail Group and sold under the trademark FRESH TIMES have included a top sheet formed of a fibrous material, a tissue fluid acquisition layer and a core formed of fluff. Diapers made by The Kendall Confab Retail Group and sold under the trademark HAPPIES have included a non-woven top sheet, a through-air-bonded (or non-woven) acquis

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