Polymerization of methylmethac-rylate with mixture of benzoyl peroxide and tertiary-butyl hydroperoxide

Claim 1

IN THE MANUFACTURE OF CLEAR METHYL METHACRYLATE GLASS, THE IMPROVEMENT WHICH COMPRISES MIXING METHYL METHACRYLATE MONOMER WITH A POLYMERIZATION CATALYST MIXTURE CONSISTING OF ABOUT 0.039 PART BY WEIGHT OF TERTIARY BUTYL HYDROPEROXIDE AND ABOUT 0.030 PART BY WEIGHT OF BENZOYL PEROXIDE PER 100 PARTS BY WEITHT OF THE METHYL METHACRYLATE, POLYMERIZING THE METHYL METHACRYLATE MONOMER IN THE PRESENCE OF THE CATALYST MIXTURE AT A TEMPERATURE OF FROM ABOUT 85* TO 90* C. FOR A PERIOD OF TIME UNTIL THE POLYMERIZATION MIXTURE REACHES THE STRING STAGE, THEREAFTER CONTAINING THE POLYMERIZATION OF THE MIXTURE IN A HEATING ZONE MAINTAINED AT A TEMPERATURE OF ABOUT 80* TO 85* C. FOR A FURTHER PERIOD OF TIME UNTIL THE POLYMERIZATION MIXTURE REACHES A GEL STAGE, THEREAFTER SUBJECTING THE RESULTING GELLED POLYMERIZATION MASS TO FURTHER POLYMERIZATION IN A HEATING ZONE MAINTAINED AT A TEMPERATURE OF ABOUT 60* C. FOR PERIOD OF TIME UNTIL THE POLYMERIZATION MASS CONTRACTS, AND THEREAFTER, CARRYING OUT THE POLYMERIZATION OF THE MASS FOR A FURTHER PERIOD OF TIME AT A TEMPERATURE OF FROM ABOUT 80* C. TO 85* C. UNTIL THE MASS IS CONVERTED TO A GLASS, THEREBY PRODUCING A CLEAR POLYMER GLASS FREE OF HAZE.