Process for making cellulose ethers having reduced yellowing and discoloration
US6306333A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 13, 1999 |
| Grant date | Oct 23, 2001 |
| Priority date | — |
| Expiry date | Oct 13, 2019 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08B11/20
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
A process for making a low molecular weight cellulose ether has the following steps: a) providing a high molecular weight cellulose ether; b) contacting it with acid to partially depolymerize it to a cellulose ether of a viscosity of about 100 cP or less; c) neutralizing the acid; d) repeating steps a)-c) to produce two or more discrete product batches of low molecular weight cellulose ether and produce at least one discrete product batch which is partially neutralized; and e) blending the two or more discrete product batches to form a combined product batch of low molecular weight cellulose ether of a pH of 4 to 6.8. The process provides a cellulose ether with reduced yellowing and discoloration.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.