POLY VINYL ALCOHOL-BASED FILM, METHOD FOR PRODUCING POLY VINYL ALCOHOL-BASED FILM, AND POLARIZING FILM

To provide a poly vinyl alcohol-based film which is excellent in dyeability and extensibility and which, even when enlargement of width, continuous length, and thickness reduction are achieved, can give a polarizing film that has high degree of polarization and no unevenness of polarization.SOLUTION: A poly vinyl alcohol-based film is characterized in that when thickness is expressed by D (mm), tension at the time when the film has been stretched 6 times in a film running direction (MD direction) in 30°C water is expressed by A (N/mm2), and tension at the time when the film has been stretched 6 times in the film running direction (MD direction) in 50°C water is expressed by B (N/mm2), the film satisfies the following relationships (1) and (2). Relationship (1) 0.6≤D×A≤1.2. Relationship (2) 0.2≤D×B≤0.4.SELECTED DRAWING: None 【課題】染色性や延伸性に優れたポリビニルアルコール系フィルムであり、幅広長尺薄型化した場合においても高い偏光度を有し、偏光ムラのない偏光膜を得ることができるポリビニルアルコール系フィルムを提供する。【解決手段】厚さＤ（ｍｍ）、３０℃の水中においてフィルムの流れ方向（ＭＤ方向）に６倍に延伸した時の張力をＡ（Ｎ／ｍｍ2）、５０℃の水中においてフィルムの流れ方向（ＭＤ方向）に６倍に延伸した時の張力をＢ（Ｎ／ｍｍ2）とした時に、下式（１）及び（２）を満足するポリビニルアルコール系フィルムである。式（１）０．６≦Ｄ×Ａ≦１．２式（２）０．２≦Ｄ×Ｂ≦０．４【選択図】なし