Patent ID: 8822614

Claim:
An acrylic thermoplastic resin comprising: 50 to 95% by mass of a repeating unit (X) derived from a methacrylate monomer represented by the following Chemical Formula (1); 0.1 to 20% by mass of a repeating unit (Y1) derived from an N-substituted maleimide monomer (a) represented by the following Chemical Formula (2); and 0.1 to 49.9% by mass of a repeating unit (Y2) derived from an N-substituted maleimide monomer (b) represented by the following Chemical Formula (3) regarding the total amount of the repeating unit (X), the repeating unit (Y1), and the repeating unit (Y2) as 100% by mass: where R 1 represents a chemical group selected from the group consisting of a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, an aryl group having 6 to 14 carbon atoms, and an aryl group having 6 to 14 carbon atoms and having a substituent; R 1 in the same molecule being the same or different; the substituent of the aryl group being one selected from the group consisting of a halogen atom, a hydroxyl group, a nitro group, a linear or branched alkoxy group having 1 to 12 carbon atoms, and a linear or branched alkyl group having 1 to 12 carbon atoms, where R 2 represents an aryl group having 6 to 14 carbon atoms or an aryl group having 6 to 14 carbon atoms and having a substituent; R 2 in the same molecule being the same or different; the substituent of the aryl group being one selected from the group consisting of a halogen atom, a hydroxyl group, a nitro group, a linear or branched alkoxy group having 1 to 12 carbon atoms, and a linear or branched alkyl group having 1 to 12 carbon atoms, and where R 3 represents a chemical group selected from the group consisting of a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, an alkyl group having 1 to 12 carbon carbon atoms and having a substituent, and a cycloalkyl group having 3 to 12 carbon atoms; R 3 in the same molecule being the same or different; the substituent of the alkyl group being one selected from the group consisting of a halogen atom, a hydroxyl group, a nitro group, and a linear or branched alkoxy group having 1 to 12 carbon atoms, wherein: the absolute value of a photoelastic coefficient (C) is not greater than 3.0×10 −12 Pa −1 , the halogen atom content is less than 0.47% by mass with reference to the mass of the acrylic thermoplastic resin and the acrylic thermoplastic resin satisfies the following optical property (i): (i) the absolute value of retardation (Re) in an in-plane direction is not greater than 30 nm, where the retardation is a value obtained by converting a value measured from a film of the acrylic thermoplastic resin into a value in terms of a 100 μm thickness.