Mitsubishi Rayon Company, Limited

Masami Ohtani

Isao Sasaki

Kozi Nishida

Hisao Anzai

Hideaki Makino

Katsuhiko Shimada

A light-transmitting plastic fiber comprising, as a core component, a methacrylimide group-containing polymer prepared by polymerizing methyl methacrylate in the absence of a chain transfer agent and then imidizing the methyl methacrylate polymer thus prepared, and another polymer as a sheath component.

Light-transmitting fiber

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.

Process for preparation of methacrylimide group containing polymer and

A methacrylimide group-containing polymer having improved moldability as well as good heat resistance and transparency is prepared by heat treating a methacrylimide group-containing polymer having imide ring structural units of the formula: ##STR1## wherein R represents a hydrogen, an alkyl, cycloalkyl, aryl, alkaryl, aralkyl or allyl group 1 to 20 carbon atoms, at a temperature of 190 to 350 C. in the presence of a tertiary amine of the formula: ##STR2## wherein R.sub.1, R.sub.2 and R.sub.3 independently represent an alkyl, aryl, aralkyl or alkaryl group having 1 to 20 carbon atoms, and two of R.sub.1, R.sub.2 and R.sub.3 may be linked to form a ring together with the nitrogen atom.

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Kuga, Japan

Masami Ohtani