| 摘要 |
PURPOSE:To improve durability and polarizing property of the titled film, and to reduce a shrinking of the titled film in a lateral direction at the time of treating it to give durability, and to produce a stable polarizing film having a broad width by treating a prescribed polarizing film with two prescribed treating baths at prescribed temp. ranges respectively. CONSTITUTION:The polarizing film composed of the film of a polyvinyl alcohol or its derivative which is orientated by adsorbing a polarizing element, is treated in the 1st. treating bath of 10-55 deg.C, and in the 2nd. treating bath of 55-80 deg.C. An aqueous solution of boric acid is preferable as the treating solution capable of giving the durability to the titled film. The concn. of boric acid is 1-15wt%, preferably, 5-10wt%. Inorg. acid salts may be added to the both prescribed treating baths or the 2nd. bath. A sulfate, a nitrate and a hydrochlorate of alkali metal or alkaline earth metal, etc., can be used as the inorg. acid salt. The additional amount of the salt is ca. 1-15%, preferably, 3-10%.
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