| 摘要 |
<p>PURPOSE:To obtain a pellicle having high stability to the change of temp. and humidity and to the irradiation of strong UV ray for long period by forming the titled film of a specific polyvinyl alcohol polymer which is converted to acetal, or a copolymer of said polymer and a monomer or a mixture of said polymer and an another polymer compatible with said polymer. CONSTITUTION:The film is composed of polyvinyl alcohol polymer which is converted to acetal and has a constituting unit shown by a formula I and a mean mol.wt. of 100,000-1000,000 or the copolymer of said polymer and the monomer copolymerizable with said polymer or the mixture of said polymer and the another polymer compatible with said polymer and has 0.5-10mum thickness. Thus, the film has high transmittance for the ray having a wavelength of 200-600nm and does not deteriorate, even in case of irradiating the strong ray for long period, and is the uniform and stable high-polymer thin film for the change of the temp. and humidity. In the formula R1 is a hydrocarbon residue of aldehyde or ketone.</p> |
