The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 26, 2023
Filed:
Sep. 24, 2021
Shin-etsu Chemical Co., Ltd., Tokyo, JP;
Akiko Miki, Tokyo, JP;
Taishi Kitaguchi, Niigata, JP;
Akira Kitamura, Niigata, JP;
Mitsuo Narita, Niigata, JP;
Shin-Etsu Chemical Co., Ltd., Tokyo, JP;
Abstract
There is provided a method for efficiently produce hydroxypropyl methyl cellulose acetate succinate (HPMCAS) having excellent flowability, where acetic acid in a reaction product mixture subjected to a wash and recovery step can be reduced. More specifically, there is provided a method for producing HPMCAS including an esterification step of esterifying hydroxypropyl methyl cellulose (HPMC) with acetic anhydride and succinic anhydride in acetic acid as a solvent to obtain a reaction product solution containing HPMCAS; a water addition step of adding water to the reaction product solution to obtain a water-added reaction product solution; an acetic acid removal step of removing at least a portion of both the solvent acetic acid and acetic acid derived from the acetic anhydride from the water-added reaction product solution to obtain a mixture having an acetic acid content reduced; and a wash and recovery step of washing the mixture and recovering the HPMCAS.