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1. (WO2001000680) PROCESS FOR MAKING CELLULOSE ETHERS HAVING REDUCED YELLOWING AND DISCOLORATION

Pub. No.:    WO/2001/000680    International Application No.:    PCT/US2000/014622
Publication Date: Fri Jan 05 00:59:59 CET 2001 International Filing Date: Sat May 27 01:59:59 CEST 2000
IPC: C08B 11/00
C08B 11/20
Applicants: THE DOW CHEMICAL COMPANY
Inventors: ROSENBERG, Steven
SPENCER, Michael, V.
SCHULZ, Gary, J.
Title: PROCESS FOR MAKING CELLULOSE ETHERS HAVING REDUCED YELLOWING AND DISCOLORATION
Abstract:
Disclosed is a process for making a low molecular weight cellulose ether. The process has the following steps: a) providing a high molecular weight cellulose ether of a viscosity of about 200 centipoise or more in a two percent aqueous solution at 20°C; b) contacting the high molecular weight cellulose ether with an amount of an acid sufficient to partially depolymerize it to a low molecular weight cellulose ether of a viscosity of about 100 cP or less at 20°C in a two percent aqueous solution; c) partially or substantially neutralizing the acid by contacting the low molecular weight cellulose ether with a basic compound; 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.