Production of arylene sulfide polymers

Abstract

A method is provided for producing arylene sulfide polymers employing a p-dihalobenzene, an alkali metal sulfide, lithium acetate, an N-alkyl-2-pyrrolidone, and optionally a polyhalo aromatic compound having more than two halogen substituents per molecule, preferably with the addition of a base selected from alkali metal hydroxides and alkali metal carbonates at polymerization conditions. A first composition comprising N-alkyl-2-pyrrolidone, lithium acetate and water is prepared and subjected to dehydration conditions after which a composition containing at least 50 weight percent water, an alkali metal sulfide and preferably containing a base is added to the first dehydrated composition and a second dehydration performed. A composition resulting from the second dehydration is then contacted with a p-dihalobenzene, and optionally a polyhalo aromatic compound having more than two halogen substituents per molecule, at polymerization conditions to form arylene sulfide polymers of higher molecular weight than produced without the two-step dehydration. The two-step dehydration also results in less foaming and flooding of the distillation column as compared with the process using a single dehydration.

Dependencies are inferred from the claim text.