Verfahren zur Herstellung von Styrolpolymerteilchen mit einheitlicher Groesse

摘要

1,255,237. Particulate polymers of styrene and its derivatives. SEKISUI KAGAKU KOGYO K.K. 3 April, 1969 [6 April, 1968], No. 17707/69. Headings C3C and C3P. Particulate polymers of styrene, which may have one or more substituents in the benzene nucleus, α-methyl styrene or chlorinated styrene, are made by forming a suspension in water of particles of the polymer of uniform diameter within the range 0.4-1.2 mm., adding styrene or its derivatives and a suspension polymerization catalyst, initiating polymerization and adding monomer continuously or intermittently at a rate such that the amount of monomer in suspension never exceeds 1.5 times the weight of the polymer in suspension. The suspension may contain an expanding agent, e.g. butane or pentane, which is not a solvent for the polymer or soluble in it and has a b.p. or decomposition point lower than the softening temperature of the polymer. In the examples styrene was polymerized in aq. suspension containing polyvinyl alcohol, copper acetate (to prevent monomer graft-polymerizing with the polyvinyl alcohol), benzoyl peroxide, magnesium pyrophosphate, sodium dodecylbenzenesulphonate, methyl methacrylate, butane, acrylonitrile and/or pentane.