Polyester film and image display device using the same

A polyester film with controlled in-plane retardation and thickness uniformity addresses rainbow-like color unevenness and mechanical strength issues, enhancing productivity and visibility in image display devices.

JP7882439B2Active Publication Date: 2026-06-30TOYOBO CO LTD
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Patent Information

Authority / Receiving Office
JP · JP
Patent Type
Patents
Current Assignee / Owner
TOYOBO CO LTD
Filing Date
2026-02-19
Publication Date
2026-06-30

AI Technical Summary

Technical Problem

Existing polyester films used in image display devices suffer from issues such as rainbow-like color unevenness, poor thickness uniformity, and reduced mechanical strength, leading to breakage during film formation and processing, which affects productivity and workability.

Method used

A polyester film with specific in-plane retardation, thickness uniformity, and mechanical properties, including a degree of plane orientation and NZ coefficient, is developed, ensuring high retardation and minimal thickness variation, enhancing productivity and workability while reducing iridescence.

Benefits of technology

The film achieves high in-plane retardation with excellent thickness uniformity and flatness, improving visibility and bending durability, and reducing breakage during processing, suitable for various image display device applications.

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Patent Text Reader

Abstract

This invention provides a polyester film that exhibits high in-plane retardation while maintaining excellent thickness uniformity, resulting in good productivity, workability, and flatness. [Solution] A polyester film is disclosed having an in-plane retardation of 3000 nm to 30000 nm, a plane orientation degree of 0.128 to 0.155, and a thickness variation in the film formation flow direction of 8% or less (the thickness variation is calculated as (maximum thickness - minimum thickness) / average thickness × 100 (%)).
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