High-density absorbent structures
OwnerPaul T. Weisman, Stephen A. Goldmaninventors
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Abstract
Absorbent structures comprising a mixture of hydrophilic fibers and discrete particles of a water insoluble hydrogel are disclosed. The fiber/hydrogel ratios range from about 30:70 to about 98:2. The absorbent structures have a density of from about 0.15 g/cm.sup.3 to about 1 g/cm.sup.3. The structures are flexible, and have superior absorption capacities for water and body fluids.
Claims33
A flexible, substantially unbonded, absorbent structure comprising an air-laid, substantially dry mixture of hydrophilic fibers and discrete particles of a water-insoluble, cross-linked polymeric hydrogel, in a fiber/hydrogel weight ratio from about 30:70 to about 98:2;
- said absorbent structure having a density of from about 0.15 to about 1 g/cm.sup.3, a moisture content of less than about 10% by weight of the dry absorbent structure and a Gurley Stiffness value of less than 2 grams.
A flexible, substantially unbonded, absorbent structure comprising an air-laid, substantially dry mixture of wood pulp fibers and discrete particles of a water-insoluble, cross-linked polymeric hydrogel in a fiber/hydrogel weight ratio of from about 75:25 to about 90:10, said cross-linked polymeric hydrogel being selected from the group consisting of hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, polyacrylate, co-polymers of isobutylene and maleic anhydride, and mixtures thereof, said particles having an average particle size of from about 50 microns to about 1 mm;
- said structure having a density of from about 0.15 to about 0.6 g/cm.sup.3 and a Gurley Stiffness value of less than 2 grams.
A process for making a continuous, flexible absorbent structure, comprising the following steps:
- (a) air-laying into a web a dry mixture of hydrophilic fibers and particles of a water-insoluble, cross-linked polymeric hydrogel, said mixture having a fiber/hydrogel weight ratio of from about 30:70 to about 98:2 and a moisture content of less than about 10% by weight of the mixture;
- and,
- (b) compressing the web to a density of from about 0.15 to about 1 g/cm.sup.3 and a Gurley Stiffness value of less than 2 grams.
A process for making a flexible, substantially unbonded, absorbent structure, comprising the following steps:
- (a) dry mixing of hydrophilic fibers and particles of a water-insoluble, cross-linked polymeric hydrogel in a weight ratio of from about 75:25 to about 90:10, said particles having an average size of from about 50 microns to about 1 mm, and said cross-linked polymeric hydrogel being selected from the group consisting of hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, polyacrylates, copolymers of isobutylene and maleic anhydride, and mixtures thereof to form a fiber/hydrogel mixture having a moisture content of less than 10% by weight;
- (b) air-laying of the mixture obtained in step (a) into a web;
- and
- (c) compressing the web into a density of from about 0.15 to about 0.6 g/cm.sup.3 and a Gurley Stiffness value of less than 2 grams.
Dependencies are inferred from the claim text.