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|1. (WO2018199141) POLYVINYL ALCOHOL FILM, POLARIZING FILM AND POLARIZING PLATE, AND POLYVINYL ALCOHOL FILM PRODUCTION METHOD|
|Applicants:||THE NIPPON SYNTHETIC CHEMICAL INDUSTRY CO., LTD.
|Title:||POLYVINYL ALCOHOL FILM, POLARIZING FILM AND POLARIZING PLATE, AND POLYVINYL ALCOHOL FILM PRODUCTION METHOD|
A polyvinyl alcohol film which has an excellent balance of swelling properties and stretching properties during polarizing film manufacture, does not result in rupture during thin polarizing film production, and enables a polarizing film to be obtained that exhibits high polarization performance and has few color irregularities, a polarizing film and polarizing plate using said polyvinyl alcohol film, and a polyvinyl alcohol film production method are provided. This polyvinyl alcohol film is elongate and no more than 40 μm thick, and is characterized in that, when immersed in 30°C water for 5 minutes, the swelling (SA), the width-direction swelling (SX), the length-direction swelling (SY), and the swelling (SB) during uniaxial stretch in which the stretch ratio triples at a stretch speed of 0.12 m/min in 30°C water satisfy formulas (1) to (3) below. (1)... 190% ≤ SA ≤ 230% (2)... 220% ≤ SB ≤ 310% (3)... 1.01 ≤ SY / SX ≤ 1.20