Method of making carboxylated cellulose fibers and products of the method
US6524348B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 17, 2000 |
| Grant date | Feb 25, 2003 |
| Priority date | — |
| Expiry date | Mar 23, 2021 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21H11/20
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
The invention is directed to a method of making carboxylated cellulose fibers whose fiber strength and degree of polymerization is not significantly sacrificed. The method involves the use of cyclic nitroxide free radical compounds as a primary oxidant and a hypohalite salt as a secondary oxidant in an aqueous environment. Preferably the oxidized cellulose is then stabilized against D.P. loss in alkaline environments and color reversion with a reducing agent such as sodium borohydride. Alternatively it may be treated with an oxidant such as sodium chlorite. The method results in a high percentage of carboxyl groups located at the fiber surface. The product is especially useful as a papermaking fiber where it contributes strength and has a higher attraction for cationic additives. The product is also useful as an additive to recycled fiber to increase strength. The method can be used to improve properties of either virgin or recycled fiber. It does not require high &agr;-cellulose fiber but is suitable for regular market pulps.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.