Patent ID: 8303867
Filing Date: 2012-11-06
Classification: B08B,B29C,B29D,B29K,G02B

Abstract:
1. A method for producing a polarizer, comprising: subjecting a polyvinyl alcohol film to at least a dyeing process, a stretching process and a crosslinking process, wherein the polyvinyl alcohol film has an original width of at least 2300 mm; and performing a cleaning process (1) before the dyeing process, wherein the cleaning process (1) comprises: feeding the film from a first pinch roll; allowing the film being fed to pass through at least first and second guide rolls so as to immerse the film in a cleaning bath; and cleaning the film, while stretching the film at a stretch ratio of 1.2 to 2.9 by guiding the film to a second pinch roll and using a difference in peripheral speed between the first and second pinch rolls, the first guide roll is placed outside the cleaning bath and is arranged subsequent to the first pinch roll, the second guide roll is placed in the cleaning bath, the length (b) of a pass line of the film immersed in the cleaning bath between the first and second guide rolls is adjusted to be 50 cm to 10 m, the distance (c) between the lowermost face of the first guide roll and the surface of the cleaning bath is from 0.1 cm to 30 cm, and at least the second guide roll uses an expander roll with a face length of 2300 mm or more and equal to or less than 1.5 times the original width.