Process for production of poly(arylene thioether) copolymer

A process for the production of a granular poly(arylene thioether) copolymer by reacting an alkali metal sulfide with a dihalo-aromatic component in a polar solvent containing water, which comprises using, as the dihalo-aromatic component, 98-70 mole % of a dihalo-aromatic compound free of any carboxyl group and 2-30 mole % of a dihalo-aromatic carboxylic acid containing 1-2 carboxyl groups, and performing polymerization by adding the dihalo-aromatic carboxylic acid to a polymerization reaction system in accordance with one process selected from the following processes:

• (1) at least 50 mole % of the dihalo-aromatic carboxylic acid is converted into an alkaline earth metal salt prior to its addition to the polymerization reaction system, and the amount of the dihalo-aromatic carboxylic acid which is not converted into an alkaline earth metal salt and is added to the reaction system is less than 2 mole % of the dihalo-aromatic component;
• (2) at least one compound selected from the group consisting of the hydroxides and oxides of alkaline earth metals is added together with the dihalo-aromatic carboxylic acid to the polymerization reaction system, wherein the alkaline earth metal compound is added to the reaction system in a stoichiometric amount sufficient to convert at lest 50 mole % of the dihalo-aromatic carboxylic acid into an alkaline earth metal salt and the amount of the dihalo-aromatic carboxylic acid which is not converted into an alkaline earth metal salt in the reaction system is less than 2 mole % of the dihalo-aromatic component;
• and
• (3) at least one compound selected from the group consisting of the hydroxides and oxides of alkaline earth metals is added to the reaction system together with a mixture of a preformed alkaline earth metal salt of a portion of the dihalo-aromatic carboxylic acid, and the remainder of the dihalo-aromatic carboxylic acid, wherein the alkaline earth metal compound is added to the reaction system in a stoichiometric amount such that at least 50 mole % of the charged dihalo-aromatic carboxylic acid will be converted into an alkaline earth metal salt in the reaction system and the amount of the dihalo-aromatic carboxylic acid which is not converted into an alkaline earth metal salt in the reaction system is less than 2 mole % of the dihalo-aromatic component.