ETHYLENE-TETRAFLUOROETHYLENE AND TETRAFLUOROETHYLENE- HEXAFLUOROPROPYLENE COPOLYMER FILMS WHICH HAVE EXCELLENT LIGHT TRANSMISSIVITY

摘要

PROBLEM TO BE SOLVED: To provide ethylen-tetrafluoroethylene and tetrafluoroethylene- hexafluoropropylene copolymer films of which the light transmittance is remarkably improved as compared with that of conventional films. SOLUTION: The ethylene-tetrafluoroethylene copolymer film having excellent light transmissivity (light transmittance is 90% or more in the film of 25μm thickness at 300 nm) and the tetrafluoroethylene-hexafluoropropylene copolymer film having excellent light transmissivity (light transmittance is at least 90% in the film of 25μm thickness at 250 nm) are obtained by biaxially stretching their original films using assist method.