Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Patent
1998-04-16
2000-01-04
Weiss, John G.
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
502401, 428402, A61F 1315, B01J 2022, B32B 516
Patent
active
060111968
DESCRIPTION:
BRIEF SUMMARY
FIELD
The present invention relates to an absorbent material which, upon contacting liquids such as water, body exudates and the like, swells and imbibes such liquids; a method of making such absorbent materials; and absorbent articles such as diapers, adult incontinence pads, sanitary napkins, and the like, incorporating such absorbent materials.
BACKGROUND
Water-insoluble, water-swellable, hydrogel-forming absorbent polymers are capable of absorbing large quantities of liquids such as water, body exudates or fluids (e.g., urine, blood, menstrual fluid), industrial fluids and household; fluids and are further capable of retaining such absorbed liquids under moderate pressures. The absorption characteristics of such polymer materials make them especially useful for incorporation into absorbent articles such as disposable diapers, adult incontinence pads and briefs, catamenial products such as sanitary napkins, and the like.
The development of highly absorbent members used in such absorbent articles are the subject of substantial commercial interest. A highly desired characteristic for such products is thinness. For example, thinner diapers are less bulky to wear, fit better under clothing, and are less noticeable. They are also more compact in the package, making the diapers easier for the consumer to carry and store. Compactness in packaging also results in reduced distribution costs for the manufacturer and distributor, including less shelf space required in the store per diaper unit.
The ability to provide thinner absorbent articles such as diapers has been contingent on the ability to develop relatively thin absorbent cores or structures that can acquire and store large quantities of discharged body fluids; in particular, urine. In this regard, the use of certain absorbent polymers often referred to as "hydrogels," "superabsorbents" or "hydrocolloid" material has been particularly important. See, for example, U.S. Pat. No. 3,699,103 (Harper et. al), issued Jun. 13, 1972, and U.S. Pat. No. 3,770,731 (Harmon), issued Jun. 20, 1972, which disclose the use of such absorbent polymers (hereafter "water-insoluble, absorbent, hydrogel-forming polymers") in absorbent articles. Indeed, the development of thinner diapers has been the direct consequence of thinner absorbent cores that take advantage of the ability of these hydrogel-forming absorbent polymers to absorb large quantities of discharged body fluids, typically when used in combination with a fibrous matrix. See, for example, U.S. Pat. No. 4,673,402 (Weisman et. al), issued Jun. 16, 1987 and U.S. Pat. No. 4,935,022 (Lash et. al), issued Jun. 19, 1990, which disclose dual-layer core structures comprising a fibrous matrix and hydrogel-forming absorbent polymers useful in fashioning thin, compact, non-bulky diapers.
Prior absorbent structures have generally comprised relatively low amounts (e.g., less than about 50% by weight) of water-insoluble, absorbent, hydrogel-forming polymers. There are several reasons for this. The hydrogel-forming absorbent polymers employed in prior absorbent structures have generally not had an absorption rate that would allow them to quickly absorb body fluids, especially in "gush" situations. This has necessitated the inclusion of fibers, typically wood pulp fibers, to serve as temporary reservoirs to hold the discharged fluids until absorbed by the hydrogel-forming absorbent polymer.
More importantly, many of the known hydrogel-forming absorbent polymers exhibited gel blocking when they are used in absorbent articles in a high concentration. "Gel blocking" occurs when particles of the hydrogel-forming absorbent polymer are wetted and the particles swell so as to inhibit fluid transmission to other regions of the absorbent structure. Wetting of these other regions of the absorbent member therefore takes place via a very slow diffusion process. In practical terms, this means acquisition of fluids by the absorbent structure is much slower than the rate at which fluids are discharged, especially in gush situations. Leakage fro
REFERENCES:
patent: 5851672 (1998-12-01), Wang et al.
Cho Eui-Boo
Hayashi Yumiko
Rezai Ebrahim
Wang Lin
Cogut Catherine
Milbrada Edward J.
Miller Steven W.
Rasser Jacobus C.
The Procter & Gamble & Company
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