1results about How to "Good crystallinity" patented technology

A polyvinyl alcohol (PVA) film is provided that exhibits low leaching of PVA-based resin into water during polarization film manufacturing, suppressed contamination of the chemical bath during manufacturing, high productivity with few foreign defects, and excellent stretch processability during manufacturing. A PVA-based film is provided in which, on both surfaces of the PVA-based film, a region extending from the surface layer of each film surface to a depth of 1 μm satisfies the following formula (1), and the weight swelling degree is 185% or more and 210% or less. |K| ≥ 3.5 × 10 ‑5 ……(1). (Here, |K| is the absolute value of the ratio (slope) of the change in the magnitude of birefringence from the surface to a depth of 1μm.)