Abstract:
In a process for preparing an esterified cellulose ether a cellulose ether is esterified 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 in the presence of an alkali metal carboxylate and an aliphatic carboxylic acid, wherein the molar ratio [alkali metal carboxylate/anhydroglucose units of cellulose ether] is not more than [1.20/1] and the molar ratio [aliphatic carboxylic acid/anhydroglucose units of cellulose ether] is from [3.55/1] to [9.0/1].
Abstract:
In a process for preparing an esterified cellulose ether a cellulose ether is esterified 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 in the presence of an alkali metal carboxylate and an aliphatic carboxylic acid, wherein the molar ratio [alkali metal carboxylate/anhydroglucose units of cellulose ether] is not more than [1.20/1] and the molar ratio [aliphatic carboxylic acid/anhydroglucose units of cellulose ether] is from [3.55/1] to [9.0/1].
Abstract:
Two or more esters of a cellulose ether, each having the same ether and ester substituents but different weight average molecular weights are prepared in a process which comprises the steps of esterifying a cellulose ether 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 in the presence of an aliphatic carboxylic acid as a reaction diluent in two or more separate reactions, wherein in each reaction a different molar ratio [aliphatic carboxylic acid/anhydroglucose units of cellulose ether] is used to produce esters of the cellulose ether of different weight average molecular weights.