Method for producing granular polyarylene sulfide, method for increasing average particle size of granular polyarylene sulfide, method for enhancing particle strength of granular polyarylene sulfide, and granular polyarylene sulfide

A method for increasing an average particle size of granular polyarylene sulfide, the method comprising:

• 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 selected from the group consisting of carboxylates, alkali metal chlorides, organic sulfonates, alkali metal sulfates, alkali earth metal oxides, alkali metal phosphates, and alkali earth metal phosphates;
• wherein an amount of the auxiliary agent is from 0.1 to 5 mol % per 1 mol of the sulfur source, and
• wherein step 3 is performed in the presence of from 4.1 to 14 mol of water per 1 kg of the organic amide solvent.

A method for enhancing a particle strength of granular polyarylene sulfide, the method comprising:

• 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 selected from the group consisting of carboxylates, alkali metal chlorides, organic sulfonates, alkali metal sulfates, alkali earth metal oxides, alkali metal phosphates, and alkali earth metal phosphates;
• an amount of the auxiliary agent is from 0.1 to 5 mol % per 1 mol of the sulfur source, and step 3 is performed in the presence of from 4.1 to 14 mol of water per 1 kg of the organic amide solvent.