Process for producing polarizing element, polarizing element, polarizing plate, optical film, and image display

• Main Authors: TSUJI, MITSUHIKO, FUTAMURA, KAZUNORI, SHIGETOMI, KIYOE, TAKEDA, TETSUROU, NISHIMURA, AKINORI, MURATE, KENROU, OGOMI, DAISUKE
• Format: Patent
• Language: Chinese; English
• Published: 16.07.2009
• Subjects: AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING; CHEMISTRY; COMPOSITIONS BASED THEREON; GENERAL PROCESSES OF COMPOUNDING; INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS; METALLURGY; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; ORGANIC MACROMOLECULAR COMPOUNDS; PERFORMING OPERATIONS; PHYSICS; PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCESIN A PLASTIC STATE; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDEDFOR; SHAPING OR JOINING OF PLASTICS; THEIR PREPARATION OR CHEMICAL WORKING-UP; TRANSPORTING; WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE, IN GENERAL; WORKING-UP

A process for producing a polarizing element which comprises subjecting a polyvinyl alcohol film to at least a dyeing step, a crosslinking step, and a stretching step and then to a drying step.In the drying step, the film which has undergone the preceding steps and has a water content of 25-55 wt.% is dried to lower the water content of the film by at least 15 wt.%, whereby the water content of the film is regulated to 5-35 wt.%. The drying step includes a rapid drying stage in which the water content of the film is lowered by at least 10 wt.% in a period which accounts for 1/2 to 1/30 the overall drying time. A polarizing element obtained by this process has durability and has satisfactory optical properties in a wide region.