Patent ID: 7456239

Claim:
An impact-modified polymethyl methacrylate molding composition resistant to hot water cycles, wherein said impact-modified polymethyl methacrylate molding composition consists essentially of: 1) from 70 wt. % to 99 wt. % of a polymethyl methacrylate matrix composition having an average molar mass molecular weight of from 130,000 g/mol to 190,000 g/mol, wherein said polymethyl methacrylate matrix composition consists essentially of: a) from 80 wt. % to 99.5 wt. % methyl methacrylate; and b) from 0.5 wt. % to 20.0 wt. % vinylic comonomer; and 2) from 1 wt. % to 15 wt. % of an impact-modifier composition in the form of a crosslinked elastomeric particle, wherein said impact-modifier composition consists essentially of: a) from 50 wt. % to 70 wt. % methyl methacrylate; b) from 20 wt. % to 40 wt. % butyl acrylate, butadiene, or both; c) from 0.1 wt. % to 2 wt. % allyl methacrylate; and d) from 0.5 wt. % to 5 wt. % vinylic comonomer.