Polycarboxylic acid crosslinked cellulosic fibers

• US 6,620,865 B2
• Filed: 08/05/2002
• Issued: 09/16/2003
• Est. Priority Date: 03/25/1994
• Status: Expired due to Fees

• Current Assignee: Weyerhaeuser NR Company (Weyerhauser)
• Original Assignee: Weyerhaeuser Company (Weyerhauser)
• Inventors: Neogi, Amar N., Westland, John A., Jewell, Richard A.
• Primary Examiner(s): SZEKELY, PETER A
• Application Number:
  US10/213,205
• Publication Number:
  US 20030121623A1
• Time in Patent Office: 407 Days
• Field of Search: 525/54.21, 525/54.23, 525/35, 524/13, 524/14, 162/157.2, 162/157.6, 162/158
• US Class Current: 524/13
• CPC Class Codes: A61L 15/24 Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds; Derivatives thereof A61L15/225 takes precedence
• CPC Class Codes: A61L 15/28 Polysaccharides or their derivatives A61L15/225 takes precedence
• CPC Class Codes: C08B 15/10 Crosslinking of cellulose
• CPC Class Codes: C08L 1/00 Compositions of cellulose, modified cellulose or cellulose derivatives
• CPC Class Codes: C08L 1/08 Cellulose derivatives
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 35/00 Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a carboxyl radical, and containing at least one other carboxyl radical in the molecule, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
• CPC Class Codes: D06M 13/123 Polyaldehydes; Polyketones
• CPC Class Codes: D06M 13/207 Substituted carboxylic acids, e.g. by hydroxy or keto groups; Anhydrides, halides or salts thereof
• CPC Class Codes: D06M 13/432 Urea, thiourea or derivatives thereof, e.g. biurets; Urea-inclusion compounds; Dicyanamides; Carbodiimides; Guanidines, e.g. dicyandiamides
• CPC Class Codes: D06M 15/263 of unsaturated carboxylic acids; Salts or esters thereof
• CPC Class Codes: D06M 15/333 of vinyl acetate; Polyvinylalcohol
• CPC Class Codes: D06M 15/347 of unsaturated ethers, acetals, hemiacetals, ketones or aldehydes
• CPC Class Codes: D21C 9/005 organic compounds
• CPC Class Codes: D21H 11/20 Chemically or biochemically modified fibres
• CPC Class Codes: D21H 17/07 Nitrogen-containing compounds
• CPC Class Codes: D21H 17/15 Polycarboxylic acids, e.g. maleic acid
• CPC Class Codes: D21H 17/28 Starch
• CPC Class Codes: Y10S 604/904 Tampons
• CPC Class Codes: Y10T 428/2924 Composite
• CPC Class Codes: Y10T 428/2929 : Bicomponent, conjugate, composite or collateral fibers or filaments [i.e., coextruded sheath-core or side-by-side type]

Abstract

Cellulosic fibers intrafiber crosslinked with a polymeric polycarboxylic acid crosslinking agent are disclosed. In one embodiment, the polymeric polycarboxylic acid is polyacrylic acid and, in another embodiment, the polycarboxylic acid is polymaleic acid. Methods for forming cellulosic fibers having stable intrafiber crosslinks and for forming crosslinked cellulosic fibers having low knot level are also disclosed.

Claims

1. A method for making crosslinked cellulosic fibers, comprising:

applying a crosslinking agent to a web of cellulosic fibers to provide a treated web;

partially curing the treated web to provide a mixture of crosslinked fibers and noncrosslinked fibers treated with the crosslinking agent;

separating the mixture of crosslinked and noncrosslinked fibers into individual fibers;

curing the individual fibers to provide individual crosslinked cellulosic fibers.

2. The method of claim 1, wherein the crosslinking agent comprises a polycarboxylic acid.

3. The method of claim 1, wherein the crosslinking agent comprises polyacrylic acid.

4. The method of claim 1, wherein the crosslinking agent comprises polymaleic acid.

5. The method of claim 1, wherein the crosslinking agent comprises a polymeric polycarboxylic acid.

6. The method of claim 1, wherein the crosslinking agent comprises a copolymer of acrylic acid.

7. The method of claim 1, wherein the crosslinking agent comprises a copolymer of acrylic acid and a monoalkyl substituted phosphinate.

8. The method of claim 1, wherein the crosslinking agent comprises a copolymer of acrylic acid and a monoalkyl substituted phosphonate.

9. The method of claim 1, wherein the crosslinking agent comprises a copolymer of maleic acid.

10. The method of claim 1, wherein the crosslinking agent comprises a copolymer of maleic acid and a monoalkyl substituted phosphinate.

11. The method of claim 1, wherein the crosslinking agent comprises a copolymer of maleic acid and a monoalkyl substituted phosphonate.

12. The method of claim 1, wherein the crosslinking agent comprises a copolymer of acrylic acid and maleic acid.

13. The method of claim 1, further comprising applying a crosslinking catalyst to the web of cellulosic fibers before partially curing the treated web.

14. The method of claim 13, wherein the crosslinking catalyst comprises an alkali metal salt of a phosphorus-containing acid.

15. The method of claim 13, wherein the crosslinking catalyst comprises an alkali metal hypophosphite.

16. The method of claim 13, wherein the crosslinking catalyst comprises sodium hypophosphite.

17. The method of claim 13, wherein the crosslinking catalyst is applied in an amount from about 5 to about 20 percent by weight based on the weight of the crosslinking agent.

18. The method of claim 1, wherein the crosslinking agent is applied in an amount from about 1 to about 10 percent by weight based on the weight of the cellulosic fibers.

19. The method of claim 1, wherein the crosslinking agent is applied in an amount from about 2 to about 8 percent by weight based on the weight of the cellulosic fibers.

20. The method of claim 1, wherein the crosslinking agent is applied in an amount from about 3 to about 6 percent by weight based on the weight of the cellulosic fibers.