PURPOSE: To control pyrolysis of α-methyl-styrene-base copolymer containing volatile matter and evaporate it to a high level by kneading it with water in a specific screw extruder and removing the volatile matter.
CONSTITUTION: A method for producing α-methyl-styrene-base copolymer of low volatile matter content, in which the copolymer solution containing 1wt.% or more of volatile matter (2) is supplied from the hopper (1) to the screw extruder whose barrel is kept at 180 to 300°C, and is transferred to the downstream unit by means of the screw (100,) while being kneaded. The volatile matter is released through the vacuum line (8) kept at a vacuum of 200Torr. or less from the vents (3), (4) and (5), while water is added through the water nozzles (6) and (7) to the copolymer to 0.01 to 20wt.% on the copolymer.
SAITO KEIICHI
YAMAMOTO TOSHIHIRO
YAMAOKA IKURO
NIPPON STEEL CORP