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:
Aug. 04, 2020
Filed:
Mar. 24, 2017
Kureha Corporation, Tokyo, JP;
Akihiro Konno, Tokyo, JP;
Hiroyuki Sato, Tokyo, JP;
KUREHA CORPORATION, Tokyo, JP;
Abstract
The present invention provides a method for producing granular polyarylene sulfide (PAS) with increased average particle size and enhanced particle strength, a method for increasing the average particle size of granular PAS, a method for enhancing the particle strength of granular PAS, and granular PAS. The method for producing PAS according to the present invention includes: step 1: a preparation step of preparing a mixture containing an organic amide solvent, a sulfur source, water, a dihalo aromatic compound, and an alkali metal hydroxide; step 2: a pre-stage polymerization step of initiating a polymerization reaction by heating the mixture to produce a prepolymer having a dihalo aromatic compound conversion ratio of not less than 50% in the presence of less than an equimolar amount of an alkali metal hydroxide per 1 mol of the sulfur source; step 3: a post-stage polymerization step of continuing the polymerization reaction in the presence of not less than an equimolar amount of an alkali metal hydroxide per 1 mol of the sulfur source to obtain a reaction product mixture; and step 4: a cooling step of cooling the reaction product mixture after the post-stage polymerization step; wherein step 4 is performed in the presence of at least one type of auxiliary agent such as a carboxylate.