Kuraray Co., Ltd.

Tetsushi Hayashi

Takanori Isozaki

Naoki Fujiwara

Toshio Nakai

Hajime Nishiuma

The invention provides a continuous method for producing polarizing films that includes a step of monoaxially stretching a polyvinyl alcohol film having a width of at least 2 m in an aqueous boric acid solution, wherein the polyvinyl alcohol film is stretched on the condition that it satisfies the following formulae (1) and (2):A&#x2267;5 (m)&#x2003;&#x2003;(1)&#x2267;0.5 (min) (2)wherein A indicates the stretching distance (m); and B indicates the stretched film speed (m/min). The method gives wide polarizing films of wide and good polarization performance, and the polarizing films thus produced are useful as the material for polarizers that may be in large-size liquid-crystal displays.

Process for producing polarizing film

The invention is a film of a vinyl alcohol polymer that contains from 0.01 to 20 mol % of cationic group-containing units and contains from 0.5 to 24 mol % of &#x3b1;-olefin units having at most 4 carbon atoms. The polyvinyl alcohol film gives polarizing films and polarizer which are resistant to water and have good polarizing properties and which are free from a problem of irregular coloration.

Polyvinyl alcohol film and polarizing film

The invention is a polyvinyl alcohol film having an YI value of at most 20, which is formed of a modified polyvinyl alcohol having a degree of polymerization of from 1500 to 5000, an ethylene unit content of from 1 to 4 mol % and a 1,2-glycol bond content of at most 1.4 mol %. The polyvinyl alcohol film gives polarizing films that contain no impurities and have good polarization performance, durability and hue stability.

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Kurashiki, Japan

Tetsushi Hayashi