Manufacturing method for oriented film, polarizing film, polarizing plate, and visual display

Abstract

An oriented film of polyvinyl alcohol derived film with reduced stretch irregularity and uniform orientation in a wide range of a stretching ratio is obtained by a manufacturing method for an oriented film, comprising the steps of: contacting a non-stretched film, comprising polyvinyl alcohols or derivatives thereof, with moisture percentage adjusted to no more than 10%, to at least one heating roll currently driven and heating the film at no less than 70° C.; subsequently giving a tension and stretching using a peripheral velocity difference between the heating roll concerned and a stretch roll in a position ahead of said heating roll in a running direction of the film.

Dependencies are inferred from the claim text.