| 摘要 |
PURPOSE:To obtain the good transparency and durability of the title body at a broad wavelength region from a near UV ray to a far UV ray, and the sufficient film strength of the body by composing a transparent thin film of a specified polyvinyl acetal or polyvinyl propional. CONSTITUTION:The transparent thin film is composed of the polyvinyl acetal or the polyvinyl propional which is shown by formula I, and has a vinyl acetate component of <=10mol.% and a degree of acetalization of >=60mol.%. In formula I, R is methyl or ethyl group. Thus, the good transparency and durability of the body at the broad wavelength region from the near UV ray to the far UV ray are obtd., and the excellent mechanical strength and productivity of the body are obtd. |
