Method for producing hydroxypropyl methylcellulose acetate succinate

Abstract

Provided is a method capable of productively producing, even after reducing the amount of an aliphatic carboxylic acid used, hydroxypropyl methylcellulose acetate succinate (HPMCAS) with an equivalent level of molecular weight as compared to before reducing the amount of the aliphatic carboxylic acid. The production method includes at least an esterification reaction step of obtaining a hydroxypropyl methylcellulose acetate succinate-containing reaction solution by subjecting hydroxypropyl methylcellulose, an acetylating agent and a succinoylating agent to an esterification reaction under the presence of an aliphatic carboxylic acid and a polyalcohol.

Dependencies are inferred from the claim text.