延伸フィルムの製造方法及び偏光フィルムの製造方法

Japanese Patent JP6669467

B2

PROBLEM TO BE SOLVED: To provide a method for producing a stretched film which enables a high stretch ratio to a TD (film width direction) and is made from a polyvinyl alcohol resin capable of suppressing a bowing phenomenon, and to provide a method for producing a polarizing film exhibiting good optical performance using the same.SOLUTION: There is provided a method for producing a stretched film which includes a stretch step of stretching a polyvinyl alcohol resin film to obtain a stretched film, where the stretch step includes a simultaneous biaxial stretch step of simultaneously performing stretch to a TD and contraction to an MD, and when a TD stretch ratio at the start of the simultaneous biaxial stretch step is represented by A[time] and a TD stretch ratio at the end thereof is represented by A[time], in the simultaneous biaxial stretching in a TD stretch ratio range of Ato n A(n is number satisfying of 0