| 摘要 |
Impact-resistant modified styrene polymers having the characteristics: molecular weight Mv 150,000 to 170,000; gel content exceeding 22%; degree of swelling of 11.5 to 13.5 and a mean gel particle diameter of 1.7 to 4.5 microns are produced by continuously polymerizing a styrene solution of polybutadiene, possibly in the presence of diluents, by means of a cascade consisting of at least three continuous stirred tank reactors, at rising temperatures and in the presence of organic peroxide initiators. The process steps are carried out as follows: (a) in a first continuous stirred tank reactor, a continuously introduced solution of styrene containing from 8 to 10.5% by weight (referred to the amount of input styrene) of polybutadiene rubber with more than 85% of a cis-1,4-structure, is polymerized in the presence of 1 to 7 m moles of an initiator per kilogram of styrene, where the initiator concentration is based upon a peroxide group or an equivalent amount of such with several peroxide groups having a half-life time exceeding 5 and less than 40 hours at 100 DEG C. (measured in benzene), for a residence time of 0.8 to 1.6 hours with shearing at temperatures of about 110 DEG to 140 DEG C., to a solid content of about 28 to 42% by weight; (b) polymerization proceeds after transfer into one, two or three further agitation vessels at temperatures of about 130 DEG to 160 DEG C., for a total residence time of about 1.0 to 1.8 hours, to a solid content of about 60 to 73% by weight; (c) polymerization proceeds after transfer into a further continuous stirred tank reactor at a temperature of about 150 DEG to 175 DEG C. and a dwell time of about 1.2 to 2.5 hours up to a solid content exceeding 75% by weight and a residual initiator content less than 1% by weight of the original amount; and (d) the substance is rid of volatile components at temperatures less than 260 DEG C. under reduced pressure.
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