| 摘要 |
Suspension polymers of a) from 80 to 100% by weight of methyl methacrylate and b) from 0 to 20% by weight of further monomers capable of undergoing free radical polymerization, are obtainable by polymerization at a temperature of from 100 degrees to 140 degrees C. which is virtually constant over the major part of the polymerization time by means of an initiator system consisting of two or more peroxide initiators I having different decomposition temperatures T at which in each case half of the initiator has decomposed after 1 hour, wherein the initiator Imin having the lowest decomposition temperature has a decomposition temperature Tmin of from 60 degrees to 100 degrees C., the initiator Imax having the highest decomposition temperature has a decomposition temperature Tmax of from 100 degrees to 140 degrees C., the difference between Tmax and Tmin is greater than 10 degrees C. and Imax is a perketal of the general formula (1) (* CHEMICAL STRUCTURE *) (1) where R1 and R2 are identical or different alkyl radicals of 1 to 5 carbon atoms and R1 and R2 may be bonded to form a 5-membered or 6-membered ring and R3 is tert-butyl or tert-amyl, and further initiators In which, if desired, may be concomitantly used have decomposition temperatures Tn of from Tmin to Tmax.
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