| 摘要 |
PURPOSE: To obtain a styrene-methacrylic acid copolymer which can stably produce a foam having a good surface state while retaining the mechanical characteristics and flowability similar to those of a conventional resin by using a specific org. peroxide as the polymn. initiator in copolymerizing styrene and methacrylic acid. CONSTITUTION: In copolymerizing 70-99wt.% styrene monomer with 1-30wt.% methacrylic acid monomer, an org. peroxide represented by the formula (wherein R is tert-alkyl or tert-aralkyl; and R1 and R2 are each 1-2C alkyl) in an amt. of 0.0005-0.2 pt.wt. (based on 100 pts.wt. polymn. raw material soln.) is used as the polymn. initiator. Thus is obtd. a styrene-methacrylic acid copolymer having a wt. average mol.wt. (by gel permeation chromatography, in terms of polystyrene) of 100,000-400,000 and a content of methacrylic acid unit of 1-30wt.%. |
