Patent ID: 6448354
Filing Date: 2002-09-10
Classification: C08F

Abstract:
A method for producing a methyl methacrylate syrup having a viscosity of 10 to 500,000 mPaÂ·s at 25Â° C. and containing a polymer having a weight average molecular weight of 20,000 to 500,000 when measured by gel permeation chromatography, the method comprising the steps of.(1) preparing a starting material comprising methyl methacrylate or a monomer mixture mainly comprising methyl methacrylate, and dividing the starting material into 20 to 70% by, weight of an initial charge and 30 to 80% by weight of an after-charge; (2) heating the initial charge in a reactor; (3) adding a whole portion of a chain transfer agent at the time when the initial charge reaches a reaction temperature; (4) adding the after-charge over 0.1 to 10 hours together with a polymerization initiator having a half-life of 10 to 300 seconds at the reaction temperature; (5) continuing the heating after the addition of the after-charge and the polymerization initiator is completed; and (6) adding a hindered phenol polymerization inhibitor at the time the heating is finished.