Process for the isolation and purification of polyarylene sulphides

A process for the recovery of polyarylene sulphides from their reaction mixtures including a reaction solvent, characterized in that

• a) the reaction solvent is not contacted with any other detergent,
• b) the reaction mixture is worked up at a constant or rising temperature, and
• c) the salts formed are removed from the reaction mixture within a temperature range whose lower temperature limit is determined by the temperature at which the polyarylene sulphide formed is still soluble in the reaction solvent and whose upper temperature limit is determined by the temperature at which the reaction solvent and the polyarylene sulphide formed are still thermally stable,
• d) the separated salts formed are subjected to an after-washing with the reaction solvent within the temperature limits defined under c),
• e) for recovery of the reaction solvent, the separated salts are dried within a temperature range whose upper limit is determined by the thermal stability of the reaction solvent while the minimum pressure during drying is determined by the capacity for condensation of the reaction solvent,
• f) the polymer produced is isolated from the filtrate,
• g) and is then present as a melt which is subjected to washing with water at pH<=6 without lowering of the temperature, and
• h) the now acid polyarylene sulphide melt is washed with water until neutral without lowering of the temperature, and
• i) the pressure in this polyarylene sulphide melt which has been washed until neutral is reduced from the extraction pressure to a pressure of from 0.001 to 1 bar, and the polyarylene sulphide melt is isolated by means of a vacuum extrusion or direct granulation.