| 摘要 |
PROBLEM TO BE SOLVED: To prevent the gel formation, inhibit the molecular scission and cross- linking during solvent removal, and improve the color tone and resistance to devitrification of a block copolymer by subjecting a conjugated diene and a vinylarom. hydrocarbon to block copolymn. in a hydrocarbon solvent in the presence of an organolithium compd. as the initiator and then to a specific treatment. SOLUTION: A hydrocarbon solvent is directly removed from a soln. of a block copolymer obtd. by copolymerizing a conjugated diene and a vinylarom. hydrocarbon in the solvent in the presence of an organolithium compd. as the initiator and having a vinylarom. hydrocarbon content of 10wt.% or higher but lower than 65wt.% or a hydrogenation product thereof, subject to the condition that the solvent removal process comprises the step of adding a reaction stopper to a polymerizer, the step of adjusting the pH to 6.5-8.5, the step of adding a phenolic stabilizer, and the step of removing 5-25wt.% of the solvent at a polymer temp. in an air-exhausting zone of 150-200 deg.C, adding a phosphorus stabilizer, and introducing into a die at the downstream side to cut with a cutter into pellets. |
