Patent ID: 11970556
Assignee: ASAHI KASEL KABUSHIKI KAISHA
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC C  G | IPC C  G

Claim 5:
6. A method of producing the methacrylic resin according to claim 1, the structural unit (X) having an N-substituted maleimide monomer-derived structural unit in a main chain thereof, and the methacrylic resin having a photoelastic coefficient with an absolute value of 3.0×10−12 Pa−1 or less, the method comprising:
a pretreatment step of water washing and/or dehydrating N-substituted maleimide so that an amount of 2-amino-N-substituted succinimide in a solution of N-substituted maleimide is 5 ppm by mass or less relative to 100 mass % of N-substituted maleimide in the solution of N-substituted maleimide;
a polymerization step of performing polymerization using the solution of N-substituted maleimide obtained through the pretreatment step; and
a devolatilization step of devolatilizing a polymerization solution obtained through the polymerization step using a devolatilization apparatus without any rotating part.