| 摘要 |
Polymers are made from a monomeric or partially polymerized material consisting solely of methyl methacrylate, or of a mixture of methyl methacrylate and a copolymerizable monoethylenically unsaturated compound, by continuously feeding the polymerizable substance, in admixture with from 0,001%-5% of its weight of a free radical organic polymerization catalyst which has a half-life of not less than one minute nor greater than 60 minutes at a temperature selected from the range of from 130 DEG -150 DEG C., but in the absence of a dispersing or solvent medium, into a reaction apparatus having one or more feed inlets connected by a duct to a delivery outlet, the material being caused to flow along at least part of the duct through at least one zone maintained at a temperature which is selected from the range of from 130 DEG -150 DEG C., and at which the catalyst has the said half-life, and thereafter continuously discharging polymerized material from the delivery outlet of the apparatus. A suitable form of apparatus for carrying out the process is a screw extruder having a polymerization zone, a catalyst destruction zone and a vapour extraction zone in which unpolymerized monomer is removed. Catalysts specified are cumene and tert. butyl hydroperoxides, dicumyl and di-tert. butyl peroxides, di-tert. butyl diperphthalate, tert. butyl peracetate and perbenzoate and methyl ethyl ketone peroxide. Copolymerizable monomers specified are styrene, acrylonitrile, methyl and ethyl acrylates and methacrylamide. Also present during polymerization may be mercaptans, e.g. lauryl mercaptan, monothioglycol and thioglycollic acid and esters. When the starting material employed is partially polymeric, it may be obtained either by polymerizing methyl methacrylate to a syrup, e.g. by heating in the presence of an azo catalyst, or by adding solid polymer to the monomer.
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