Absorbent nonwoven fabric and its production

• US 5,607,550 A
• Filed: 02/07/1995
• Issued: 03/04/1997
• Est. Priority Date: 08/13/1992
• Status: Expired due to Term

• Current Assignee: Blue Star Fibres Company Limited
• Original Assignee: Courtaulds Fibers, Inc.
• Inventors: Akers, Paul J.
• Primary Examiner(s): Chin, Peter
• Application Number:
  US08/381,834
• Time in Patent Office: 756 Days
• Field of Search: 162/102, 162/146, 162/157.4, 162/9, 162/157.1, 162/157.2, 162/157.3, 162/157.6, 162/157.7
• US Class Current: 162/102
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: D21H 13/18 Polymers of unsaturated acids or derivatives thereof, e.g. polyacrylonitriles
• CPC Class Codes: D21H 21/22 Agents rendering paper porous, absorbent or bulky

Abstract

A wet-laid nonwoven fabric comprises a blend of 1 to 50% by weight of fibres of a water-swellable water-insoluble superabsorbent polymer and 99 to 50% by weight of less absorbent fibres, for example fibres having an absorbency of less than 10 g/g measured by retention to centrifuging of a 0.9% by weight saline solution.

Claims

1. A wet-laid nonwoven fabric comprising a blend of 1 to 50% by weight of fibres of weight 2 to 30 decitex per filament and length 3 to 100 mm of a water-swellable water-insoluble superabsorbent polymer, which is a crosslinked copolymer of 50 to 95% by weight ethylenically unsaturated carboxylic monomer and 5 to 50% by weight copolymerisable ethylenically unsaturated monomer, and 99 to 50% by weight of less absorbent fibres having an absorbency of less than 10 g/g measured by retention to centrifuging of a 0.9% by weight saline solution.

2. A fabric according to claim 1, wherein the less absorbent fibres comprise fibres of length 1 to 10 mm.

3. A fabric according to claim 2, wherein the less absorbent fibres comprise wood pulp fibres.

4. A fabric according to claim 2, wherein the less absorbent fibres comprise polypropylene or polyethylene fibrils.

5. A fabric according to claim 1, wherein the less absorbent fibres comprise textile fibres of length 10 to 100 mm.

6. A fabric according to claim 5, wherein the less absorbent fibres of length 10 to 100 mm are cellulosic fibres or polyester, polyamide, acrylic, polypropylene or polyethylene fibres.

7. A fabric according to claim 1, comprising a blend of 5 to 20% by weight of the superabsorbent polymer fibres and 95 to 80% by weight of the less absorbent fibres.

8. A process for the production of a wet-laid nonwoven fabric, in which process fibres having an absorbency of less than 10 g/g, measured by retention to centrifuging of a 0.9% by weight saline solution, are slurried in water, fibers of weight 2 to 30 decitex per filament and length 3 to 100 mm of a water-swellable water-insoluble superabsorbent polymer, which is a crosslinked copolymer of 50 to 95% by weight ethylenically unsaturated carboxylic monomer and 5 to 50% by weight copolymerisable ethylenically unsaturated monomer, are added to this slurry to form a mixed slurry containing both the superabsorbent polymer fibres and the less absorbent fibres, the mixed slurry is deposited as a layer on a foraminous support so that part of the water drains from the layer of slurry on the support, and the resulting fibrous layer is dried to form the nonwoven fabric.

9. A process according to claim 8, wherein the proportion of superabsorbent fibres to less absorbent fibres is from 1:

2 to 1;

50 by weight.

10. A process according to claim 8, wherein the total fibre content of the slurry as it is deposited on the foraminous support is from 0.1 to 50 grams per liter.

11. A process according to claim 8, wherein the superabsorbent polymer fibres are slurried in a water-miscible organic liquid in which they do not swell and the resulting slurry is mixed with a slurry of the less absorbent fibres in water.

12. A process according to claim 8, wherein the superabsorbent polymer fibres are added as dry fibres to a slurry of the less absorbent fibres in water.