Method for producing hypromellose acetate succinate

Patent metadata

Field	Value
Publication number	US-11319385-B2
Application number	US-201916521253-A
Country	US
Kind code	B2
Filing date	Jul 24, 2019
Priority date	Jul 25, 2018
Publication date	May 3, 2022
Grant date	May 3, 2022

Abstract

There is provided a method for producing hypromellose acetate succinate (HPMCAS), the method not requiring any special device and facilitating removal of impurities. More specifically, there is provided a method for producing HPMCAS, including an esterification step of esterifying hypromellose with an acetylating agent and a succinoylating agent in the presence of an aliphatic carboxylic acid to obtain a reaction product solution containing HPMCAS; a precipitation step of precipitating the HPMCAS by mixing the reaction product solution with water to obtain a suspension of the precipitated HPMCAS; a neutralization step of neutralizing the suspension with a basic substance to obtain a neutralized suspension; and a washing step of washing the HPMCAS contained in the neutralized suspension to obtain the washed HPMCAS.

First claim

The invention claimed is:

1. A method for producing hypromellose acetate succinate, comprising:
an esterification step of esterifying hypromellose with an acetylating agent and a succinoylating agent in the presence of an aliphatic carboxylic acid as a solvent and an alkali metal salt of a carboxylic acid as a catalyst to obtain a reaction product solution containing hypromellose acetate succinate;
a precipitation step of precipitating the hypromellose acetate succinate by mixing the reaction product solution with water to obtain a suspension of the precipitated hypromellose acetate succinate;
a pH-increasing step of mixing the suspension with a basic substance to obtain a pH-increased suspension having a pH value of from 4.10 to 5.50; and
a washing step of washing the hypromellose acetate succinate contained in the pH-increased suspension to obtain the washed hypromellose acetate succinate.

2. The method for producing hypromellose acetate succinate according to claim 1 , wherein the precipitation step and the pH-increasing step are conducted simultaneously.

3. The method for producing hypromellose acetate succinate according to claim 1 , wherein the pH-increased suspension has a pH value of from 4.41 to 5.16.

4. The method for producing hypromellose acetate succinate according to claim 1 , wherein the basic substance is an alkali metal hydroxide.

5. The method for producing hypromellose acetate succinate according to claim 2 , wherein the pH-increased suspension has a pH value of from 4.41 to 5.16.

6. The method for producing hypromellose acetate succinate according to claim 2 , wherein the basic substance is an alkali metal hydroxide.

7. The method for producing hypromellose acetate succinate according to claim 3 , wherein the basic substance is an alkali metal hydroxide.

8. The method for producing hypromellose acetate succinate according to claim 5 , wherein the basic substance is an alkali metal hydroxide.

Assignees

• Shinetsu Chemical Co

Inventors

• Kitaguchi Taishi
• Tsuchida Akiko
• Kitamura Akira
• Narita Mitsuo

Classifications

• C08B3/16 Primary

  Preparation of mixed organic cellulose esters {, e.g. cellulose aceto-formate or cellulose aceto-propionate} · CPC title

• C03B15/08

  by means of bars below the surface of the melt · CPC title

• C08B13/00 Primary

  Preparation of cellulose ether-esters · CPC title

• C08B11/20

  Post-etherification treatments of chemical or physical type, {e.g. mixed etherification in two steps}, including purification · CPC title

• C08L1/32

  Cellulose ether-esters · CPC title