Polarizing film, method for manufacturing the same, and polarizing plate

By concentrating carbodiimide compounds on the surface of polarizing films, the problems of insufficient heat resistance and durability and uneven coating of polarizing films are solved, achieving high efficiency in heat resistance, durability and uniformity, and avoiding polyolefin formation.

CN122459720APending Publication Date: 2026-07-24MITSUBISHI CHEM CORP
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
MITSUBISHI CHEM CORP
Filing Date
2025-03-26
Publication Date
2026-07-24

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Abstract

The present invention provides a polarizing film that can improve the durability of the surface of the polarizing film, further can introduce an acid-trapping agent using a simple method without improving the equipment, and can obtain a polarizing plate that has excellent heat-resistant durability for a long time. A polarizing film containing an acid-trapping agent, wherein the polarizing film comprises a polyvinyl alcohol film, and in at least one surface of the polyvinyl alcohol film, the nitrogen content in the surface layer portion from the surface to a depth of 0.5 nm in the thickness direction of the polyvinyl alcohol film is 0.05% by mass or more.
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Claims

1. A polarizing film, which is a polarizing film containing an acid scavenging agent, The polarizing film comprises a polyvinyl alcohol-based film, and in at least one surface of the polyvinyl alcohol-based film, the nitrogen content in the surface portion along the thickness direction of the polyvinyl alcohol-based film from the surface to a depth of 0.5 nm is 0.05% by mass or more.

2. A polarizing film, which is a polarizing film containing an acid scavenging agent, The polarizing film comprises a polyvinyl alcohol-based film, and in at least one surface of the polyvinyl alcohol-based film, the surface portion along the thickness direction of the polyvinyl alcohol-based film from the surface to a depth of 0.5 nm contains more than 95% of all nitrogen elements contained in the polyvinyl alcohol-based film.

3. The polarizing film according to claim 1 or 2, wherein, The acid scavenging agent is a carbodiimide compound.

4. The polarizing film according to claim 3, wherein, The carbodiimide compound has a carbodiimide equivalent of 100 to 1,000.

5. A method for manufacturing a polarizing film, which is the method for manufacturing a polarizing film according to claim 1 or 2, the method comprising a step of passing a polyvinyl alcohol-based film through multiple processing tanks. An acid scavenging agent is mixed into the final treatment solution in the treatment tank at a concentration of 0.5 g / L or higher.

6. A polarizing plate having a protective film on at least one surface of the polarizing film according to claim 1 or 2.