METHOD FOR PRODUCING GRANULAR POLYARYLENE SULFIDE, METHOD FOR INCREASING AVERAGE PARTICLE DIAMETER OF GRANULAR POLYARYLENE SULFIDE, METHOD FOR ENHANCING PARTICLE STRENGTH OF GRANULAR POLYARYLENE SULFIDE AND GRANULAR POLYARYLENE SULFIDE

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a granular polyarylene sulfide (PAS) having increased average particle diameter and enhanced particle strength, to provide a method for increasing the average particle diameter of a granular PAS, to provide a method for enhancing the particle strength of a granular PAS and to provide a granular PAS.SOLUTION: The method for producing a granular PAS comprises: a step 1: a preparation step of preparing a mixture containing an organic amide solvent, a sulfur source, water, a dihaloaromatic compound and an alkali metal hydroxide; a step 2: a pre-stage polymerization step of starting a polymerization reaction by heating the mixture to produce a prepolymer having a conversion ratio of the dihaloaromatic compound of 50% or more in the presence of less than an equimolar amount of the alkali metal hydroxide per one mole of the sulfur source; a step 3: a post-stage polymerization step of continuing the polymerization reaction in the presence of an equimolar amount or more of the alkali metal hydroxide per one mole of the sulfur source to produce a reaction product mixture; and a step 4: a cooling step of cooling the reaction product mixture after the post-stage polymerization step. The step 4 is carried out in the presence of at least one kind of assistant such as a carboxylic acid salt or the like.SELECTED DRAWING: None