GB1084274A - - Google Patents

Abstract

1,084,274. Polymerizing methacrylate esters. DEUTSCHE GOLD-UND SILBER-SCHEI. DEANSTALT. April 14, 1965 [April 18, 1964], No. 16074/65. Heading C3P. A methacrylic ester or a monomer mixture containing such an ester is polymerized by introducing into the monomer or monomer mixture at least one radical-forming catalyst whose activity A (as hereinafter defined), as determined in methyl methacrylate, is greater than 2 at 50‹ C. and at least one other radicalforming catalyst whose activity A is less than 2 at 50‹ C. and greater than 2 at 70‹ C., the polymerization mixture being heated initially at up to 60‹ C. and subsequently heated at 70‹ to 150‹ C. The activity wherein Z represents the polymerization time in hours following the induction period, U is the polymerization rate and K is the quotient of the quantity of catalyst in p.p.m. and the radical equivalent weight of the catalyst. Specified catalysts with A greater than 2 at 50‹ C. are diisopropylperoxy dicarbonate and tert.-butylperoxy pivalate and the second catalyst is e.g. benzoyl, lauroyl or diacetyl peroxide, or azodiisobutyronitrile. The methacrylate ester is preferably derived from a C 1 to C 6 alcohol and suitable comonomers are higher methacrylate esters, acrylates, acrylonitrile, acrylamide and methacrylamide. The monomer mixture may include a cross-linking agent, e.g. a dimethacrylate or diacrylate, a divinyl compound, allyl methacrylate or a diallyl compound. Polystyrene may be present in the reaction mixture. In examples, (a) a methyl methacrylate prepolymer is polymerized using diisopropylperoxy dicarbonate and lauroyl peroxide as catalysts and (b) methyl methacrylate is polymerized using diisopropylperoxy dicarbonate, or tert.-butylperoxy pivalate, and diacetyl peroxide as catalysts.