abstract |
PROBLEM TO BE SOLVED: To provide a protective film for optical parts having a low birefringence and a small change in birefringence due to stress so that product inspection of an optical part is possible without removing the film. . SOLUTION: It is composed of a copolymer of an olefin and an alkenyl aromatic compound, and has a birefringence, Δn, of 0 to 0.1. 001 is a coating material for optical products. |