To provide a method for manufacturing a protective film for a polarizing plate, the protective film exhibiting appropriate and sufficient adhesiveness as a polarizer protective member.
The method for manufacturing a protective film for a polarizing plate includes: a heating and orienting step of biaxially orienting a crystalline resin film in a longitudinal direction and a width direction while heating to obtain an oriented film; and a heat treatment step of subjecting the oriented film to a relaxation treatment in the longitudinal direction and in the width direction as well as to a heat treatment. In the method for manufacturing a protective film for a polarizing plate, when a relaxation rate in the longitudinal direction and a relaxation rate in the width direction of the oriented film in the heat treatment step are denoted by ηm (%) and ηt (%), respectively, the oriented film is subjected to the relaxation treatment in such a manner that ηm and ηt satisfy all of expressions (1): 0<ηm<10, (2): 0<ηt<10 and (3): 0.5<ηm/ηt<1.5.
Table of contents Makoto
Tomoyuki Ishimura
Kazutoshi Nakayama
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