Polarizing Plate Adhesive Layer Durability and Haze Control
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Solution Overview
Problem
Polarizing plates used in optical displays face issues with durability and crack resistance due to moisture infiltration and thermal impacts, especially when a protective film is only applied to one surface, leading to potential deterioration and reduced flexibility.
Innovation Solution
A polarizing plate design featuring a polarizer with a protective layer on one surface and a first adhesive layer on the other, comprising an adhesive resin with a glass transition temperature of 50°C or greater and a polyisocyanate curing agent modified with an allophanate group, which provides enhanced durability and flexibility while minimizing haze, and optionally a second adhesive layer for improved adhesion and stress relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a protective film is formed only on one surface of the polarizer to reduce thickness, then the polarizing plate achieves reduced thickness, but durability deteriorates due to moisture infiltration through the other surface
Solution Approach 1:
The protective function is segmented between two distinct layers: a protective film on the upper surface and an adhesive layer on the lower surface. This segmentation allows each layer to specialize in protecting against different threats (moisture from above and moisture/thermal stress from below) while maintaining reduced overall thickness.
Solution Approach 2:
The adhesive layer serves multiple functions simultaneously: it provides durability by preventing moisture infiltration, improves crack resistance under thermal impact, and enables secure mounting to the optical device. This multi-functionality resolves the contradiction by achieving both thickness reduction and durability improvement through a single integrated solution.
2Reliability
If an adhesive layer is formed on the other surface of the polarizer to improve durability and crack resistance, then durability and crack resistance are improved, but haze increases reducing transparency
Solution Approach 1:
The patent specifies precise parameter ranges for the adhesive layer: glass transition temperature of 50°C or higher and haze of 1% or less at 380-780 nm wavelength. By controlling these parameters, the adhesive layer achieves both durability improvement and transparency maintenance, resolving the contradiction between these opposing requirements.
Solution Approach 2:
The adhesive layer is formulated as a composite material combining adhesive resin with specific glass transition temperature characteristics and low haze properties. This composite structure enables simultaneous achievement of mechanical durability and optical transparency that neither component could achieve alone.
3Strength
If the adhesive layer uses standard adhesive resin to ensure adhesion, then adhesion is achieved, but flexibility deteriorates under thermal impact conditions
Solution Approach 1:
The glass transition temperature of the adhesive resin is specifically controlled to be 50°C or higher. This parameter change optimizes the balance between adhesion strength and flexibility, allowing the adhesive layer to maintain strong bonding while remaining flexible enough to resist cracking under thermal impact conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances the polarizing plate's durability and flexibility, preventing cracks and discoloration under thermal and humidity stress, while maintaining low haze and high light transmittance, suitable for both rigid and flexible displays.
Implementation Method 1
the first adhesive layer includes an adhesive resin having a glass transition temperature of about 50° C. or greater
Implementation Method 2
a polyisocyanate curing agent modified with an allophanate group
Data Source
AI summary
A polarizing plate, a method of manufacturing the same, and an optical display including the same are provided. A polarizing plate includes a polarizer and a first adhesive layer formed on a lower surface of the polarizer, and the first adhesive layer includes an adhesive resin having a glass transition temperature of about 50° C. or greater, and the first adhesive layer has a haze of about 1% or less at a wavelength of about 380 nm to about 780 nm.