ALEXANDRIA, Va., Feb. 17 -- United States Patent no. 12,552,902, issued on Feb. 17, was assigned to MITSUBISHI GAS CHEMICAL COMPANY INC. (Tokyo).
"Composition for optical material" was invented by Mariko Sado (Tokyo), Kouhei Takemura (Tokyo) and Hiroshi Horikoshi (Ibaraki, Japan).
According to the abstract* released by the U.S. Patent & Trademark Office: "A composition for an optical material contains (a) an episulfide compound, (b) a polymerization catalyst, and (c) an ester compound having a halogen at the Alpha position. The (c) ester compound having a halogen at the Alpha position is preferably at least one compound selected from the group consisting of dimethyl chloromalonate, diethyl chloromalonate, dimethyl bromomalonate, and dieth...