Thermoplastic acrylic resin, and molded product thereof

A thermoplastic acrylic resin of a copolymer comprising 10 to 70% by weight of a repeating unit derived from a methacrylate monomer represented by the following formula (1), 5 to 40% by weight of a repeating unit derived from a vinyl aromatic monomer represented by the following formula (2), and 20 to 50% by weight of a repeating unit of a cyclic acid anhydride represented by the following formula (3),

• wherein a molar ratio (B/A) is within the range of more than 1 to not more than 10, wherein (A) is a content of the repeating unit of the vinyl aromatic monomer and (B) is a content of the repeating unit of the cyclic acid anhydride, and
• the total amount of remaining monomers to 100 parts by weight of the copolymer is not more than 0.5 part by weight:
• wherein R1 represents hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, or a cycloalkyl group having 5 to 12 carbon atoms;
• wherein R2 and R3 may be the same or different from each other, and represent hydrogen atom, a halogen group, a hydroxyl group, an alkoxyl group having 1 to 12 carbon atoms, a nitro group, a linear or branched alkyl group having 1 to 12 carbon atoms, and l is an integer of 1 to 3;
• wherein R5 to R6 may be the same or different from each other, and represent hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, wherein the thermoplastic acrylic resin has the following optical property (i):
• (i) an absolute value of a photoelastic coefficient (C) being less than 2.5×10−12 Pa−1.