Abstract: Phonograph record molding compositions having polystyrene as the major constituent are formulated to have wear resistance properties superior to other polystyrene injection molded compositions while generally retaining the transparency of unmodified polystryene. Ethylene-bis-stearamide or a homolog or analog thereof is dissolved within styrene monomer and then the monomer is polymerized to obtain a polystryene matrix having a molecular distribution of ethylene-bis-stearamide or the like within and throughout the matrix. Preferably, the ethylene-bis-stearamide or the like is combined with a wax such as an olefin-based wax or a microcrystalline wax.

Abstract: A phonograph record molding composition formed by copolymerizing a vinyl aromatic monomer with an acrylic ester monomer in the presence of one or more waxes which composition is especially suitable for injection and compression molding and which is characterized by substantially improved wear resistance, particularly when compared to conventional polystyrene record molding materials. The compositions of this invention comprise about 90 to 98, preferably 94 to 97, weight percent of vinyl aromatic/acrylic ester copolymer (with the weight ratio of vinyl aromatic to acrylic ester of from about 10:1 to 40:1), about 1 to 9, preferably 3 to 6, weight percent of the wax component and about 0.1 to 3, preferably 0.1 to 0.8, weight percent of a suitable lubricant. Preferred copolymers are styrene/2-ethylhexyl acrylate and styrene/stearyl methacrylate copolymers.