Process for preparation of methacrylimide group containing polymer and

Abstract

A methacrylimide group-containing polymer having good optical characteristics, especially a resistance to coloration under heating and above to retain good light-transmitting characteristics for a long time even at a high temperature, is prepared by polymerizing methacrylic acid, a methacrylic acid ester, or a monomer mixture predominantly comprised of methacrylic acid or an ester thereof in the absence of a mercaptan chain transfer agent, and then imidizing the thus-prepared polymer. The resulting polymer is useful as the core component of a light-transmitting fiber having a core-sheath structure.