METHOD FOR PRODUCING METHYL-METHACRYLATE POLYMERS IN A RECYCLE REACTOR

摘要

The invention concerns methyl-methacrylate polymers with an heterogeneity of 1.0 to 1.2. Said polymers are obtained continuously by polymerization of monomers consisting of no less than 90 % by weight methyl-methacrylate in a recycle reactor, which has preferably at least a tubular reactor or a multitube-flow reactor, avoiding unwarranted wall deposits. Said polymers are produced in such a way that temperature during polymerization stands at 135-150 DEG C, the recycle relation is bigger than 20 when divided by the number of chargings per circulation loop, the mean effective axial circulation is faster than 5 cm/s, a polymerization initiator having a batch half change value of 3 to 10 min. is used, and the inflow concentration of the initiator is set in such a way that by a mean residence time of 1.3 to 2.5 hours a polymer rupture of 0.50 to 0.70 at the output of the reactor is achieved. Preforms having very good optical properties can be produced with the homogeneous polymers.