Patent ID: 9617351
Date: 2017-04-11
CPC Classifications: A61K,C08B

Claim:
1. An esterified cellulose ether comprising (i) aliphatic monovalent acyl groups or (ii) groups of the formula —C(O)—R —COOA, wherein R is a divalent aliphatic or aromatic hydrocarbon group and A is hydrogen or a cation, or (iii) a combination of aliphatic monovalent acyl groups and groups of the formula —C(O)—R—COOA, wherein the esterified cellulose ether has a) a viscosity of from 1.2 to 2.10 mPa·s, measured as a 2.0 wt. % solution of the esterified cellulose ether in 0.43 wt. % aqueous NaOH at 20° C., and b) a viscosity of up to 5 mPa·s, measured as a 10 wt. % solution of the esterified cellulose ether in acetone at 20° C. and wherein the esterified cellulose ether is produced by esterifying a cellulose ether having a viscosity of from 1.2 to 1.8 mPa·s, measured as a 2 wt. % solution in water at 20° C. with (i) an aliphatic monocarboxylic acid anhydride or (ii) a dicarboxylic acid anhydride or (iii) a combination of an aliphatic monocarboxylic acid anhydride and a dicarboxylic acid anhydride.