Polyarylene sulfide preparation in titanium reaction vessel with two distinct temperature ranges

Abstract

A process for the preparation of a high-molecular-weight polyarylene sulfide, which comprises subjecting an alkali metal sulfide such as sodium sulfide and a dihalo aromatic compound such as dichlorobenzene to dehalogenation sulfidation reaction in an organic amide solvent, wherein at least a part of the reaction is carried out in a reaction vessel in which at least the portion which the reaction liquid contacts is made of titanium, through at least the following two steps: (1) the step of carrying out the reaction at a temperature of 180.degree. to 235.degree. C. in the presence of water in an amount of 2.4 to 10 moles per mole of the alkali metal sulfide so that the conversion of the dihalo aromatic compound is at least 50% and the melt viscosity of the formed polyarylene sulfide does not exceed 500 P, and (2) the step of elevating the temperature to 245.degree. to 290.degree. C. in the presence of water in an amount of 2.5 to 10 moles per mole of the alkali metal sulfide with or without the addition of water to the reaction system and carrying out the reaction. The titanium reaction vessel is used for at least the step (1) and, preferably, for both the steps (1) and (2). The two-step reaction is advantageous in producing high molecular weight polyarylene sulfide.

Dependencies are inferred from the claim text.