Terpolymer of methyl methacrylate, styrene and alpha-methyl styrene

A thermoplastic molding composition M, comprising:

• A:
• 40 to 99 wt.-%, based on the molding composition M, of at least one thermoplastic terpolymer A comprising repeating units of the following monomers:
• a-1:30 to 69 wt.-%, based on the terpolymer A, of methyl methacrylate,
• a-2:30 to 69 wt.-%, based on the terpolymer A, of styrene, and
• a-3:1 to 25 wt.-%, based on the terpolymer A, of alpha-methyl styrene,
• wherein components a-1, a-2 and a-3 sum up to 100 wt.-% of the thermoplastic terpolymer A, and
• wherein the thermoplastic terpolymer A has a refractive index at 589.3 nm in the range of from 1.54 to 1.56;
• B:
• 0 to 5 wt.-%, based on the molding composition M, of at least one additive B;
• C:
• 1 to 60 wt.-%, based on the molding composition M, of at least one polymer compound C, wherein the at least one polymer compound C is a thermoplastic homopolymer and/or copolymer different from the thermoplastic terpolymer A;
• and
• wherein the polymer compound C has a refractive index at 589.3 nm in the range of from 1.52 to 1.57,
• wherein components A, B, and C sum up to 100 wt.-% of the thermoplastic molding composition M.