abstract |
(57) [Summary] [Object] To provide a film or fiber which is optically isotropic and has a small infrared absorption. [Structure] The present invention is a stretched film or fiber, characterized in that it is formed by stretching a film or fiber composed of a polymer or copolymer of methacrylonitrile as a main component near the glass transition temperature. The copolymerization component of the methacrylonitrile copolymer is at least one selected from acrylonitrile, (meth) acrylic acid ester, styrene, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl acetate. It is preferably a characteristic stretched film or fiber. |