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:
Jan. 14, 2020
Filed:
Feb. 05, 2018
Kureha Corporation, Chuo-ku, Tokyo, JP;
KUREHA CORPORATION, Tokyo, JP;
Abstract
The production method of the present invention includes: a supplying step of supplying reaction raw materials to at least one of a plurality of reaction vessels that mutually communicate through a gas phase; a polymerizing step of carrying out a polymerization reaction; and a step of removing at least some of the water present in the reaction vessels. Each of the steps is carried out in parallel, and a reaction mixture is transferred sequentially between the reaction vessels. The amount of water contained in the reaction mixture in at least one of the reaction vessels is from 0.1 moles to less than 3 moles per mole of a sulfur source, and the total amount of water contained in the reaction raw materials that are supplied is 3 moles or more per mole of the sulfur source.