Method for producing hypromellose phthalate

Patent metadata

Field	Value
Publication number	US-11319384-B2
Application number	US-201916521237-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 phthalate (HPMCP), the method not requiring any special device, and facilitating removal of impurities. More specifically, there is provided a method for producing HPMCP, including an esterification step of esterifying hypromellose with a carboxybenzoylating agent in the presence of an aliphatic carboxylic acid to obtain a reaction product solution containing HPMCP; a precipitation step of precipitating the HPMCP by mixing the reaction product solution with water to obtain a suspension of the precipitated HPMCP; a neutralization step of neutralizing the suspension with a basic substance to obtain a neutralized suspension; and a washing step of washing the HPMCP contained in the neutralized suspension to obtain the washed HPMCP.

First claim

The invention claimed is:

1. A method for producing hypromellose phthalate, comprising:
an esterification step of esterifying hypromellose with phthalic anhydride in the presence of an aliphatic carboxylic acid to obtain a reaction product solution containing hypromellose phthalate;
a precipitation step of precipitating the hypromellose phthalate by mixing the reaction product solution with water to obtain a suspension of the precipitated hypromellose phthalate;
a pH-increasing step of mixing the suspension with a basic substance to obtain a pH-increased suspension having a pH value of from 3.90 to 5.00; and
a washing step of washing the hypromellose phthalate contained in the pH-increased suspension to obtain the washed hypromellose phthalate.

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

3. The method for producing hypromellose phthalate according to claim 1 , wherein the pH-increased suspension has a pH value of from 4.24 to 5.00.

4. The method for producing hypromellose phthalate according to claim 1 , wherein the basic substance is an alkali metal hydroxide and/or an alkali metal hydrogen carbonate.

5. The method for producing hypromellose phthalate according to claim 2 , wherein the pH-increased suspension has a pH value of from 4.24 to 5.00.

6. The method for producing hypromellose phthalate according to claim 2 , wherein the basic substance is an alkali metal hydroxide and/or an alkali metal hydrogen carbonate.

7. The method for producing hypromellose phthalate according to claim 3 , wherein the basic substance is an alkali metal hydroxide and/or an alkali metal hydrogen carbonate.

8. The method for producing hypromellose phthalate according to claim 5 , wherein the basic substance is an alkali metal hydroxide and/or an alkali metal hydrogen carbonate.

Assignees

• Shinetsu Chemical Co

Inventors

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

Classifications

• C08B13/00 Primary

  Preparation of cellulose ether-esters · CPC title

• C08B3/22 Primary

  Post-esterification treatments, including purification · CPC title

• C08B3/10 Primary

  with five or more carbon-atoms, {e.g. valerate} · CPC title

• C08B11/08

  with hydroxylated hydrocarbon radicals; Esters, ethers, or acetals thereof · CPC title

• C08L1/32

  Cellulose ether-esters · CPC title