Patent ID: 7632430

Claim:
A continuous method for producing polarizing films, which comprises: monoaxially stretching a polyvinyl alcohol film having a width of at least 2 m in an aqueous boric acid solution, such that the polyvinyl alcohol film is drawn to a draw ratio of at least 5 times, and the polyvinyl alcohol film is stretched based on the following conditions: A≧5 (m) (1) 3≧ A/B≧ 0.5 (min) (2) A/C≧ 5 (3) wherein A indicates the stretching distance (m), B indicates the stretched film speed (m/min), and C is the stretched film width (m), wherein the resultant polarized film has a degree of polarization of at least 99.97% and a dichroic ratio of at least 64.