Epoxy Oxetane Protective Layer for Polarizer Shrinkage
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Solution Overview
Problem
Existing polarizing plates with elongation-type polyvinyl alcohol-based polarizers face challenges with stress-induced tearing due to shrinkage at high temperatures, particularly when directly forming protective films without a substrate, leading to light leakage and reduced durability.
Innovation Solution
A polarizing plate with a protective layer composed of a cured photocurable composition containing epoxy and oxetane-based compounds, directly adhered to the polarizer, which satisfies specific FTIR intensity ratios to enhance toughness and hardness, minimizing shrinkage and light leakage under high temperature and humidity conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If a protective film is directly formed on the polarizer without a substrate, then the polarizing plate can be thinned and lightweight, but the polarizer becomes prone to tearing due to stress from shrinkage at high temperatures
Solution Approach 1:
The patent uses a composite protective layer made of photocurable composition containing epoxy compound and oxetane-based compound. This composite material provides both the desired thinness and superior mechanical strength to prevent tearing, resolving the contradiction between weight reduction and durability maintenance.
Solution Approach 2:
The patent changes the chemical composition parameters of the protective layer by using specific epoxy and oxetane-based compounds with controlled ratios. This parameter optimization enables the protective layer to have high tensile modulus and storage modulus, preventing polarizer tearing while maintaining thinness.
2Ease of manufacture
If a protective film is directly formed on the polarizer, then manufacturing costs and processes are minimized, but light leakage occurs due to stress-induced cracks at high temperatures
Solution Approach 1:
The photocurable composition combines epoxy compound and oxetane-based compound to create a protective layer with high tensile modulus and storage modulus. This composite structure prevents stress-induced cracks that cause light leakage, while maintaining manufacturing simplicity.
Solution Approach 2:
The patent uses a thin protective layer formed directly on the polarizer, replacing the need for expensive and complex multi-layer substrate structures. This single-layer approach eliminates light leakage issues while keeping manufacturing simple and cost-effective.
3Reliability
If the protective layer has high tensile modulus and storage modulus, then shrinkage and light leakage are suppressed, but the material composition becomes more complex
Solution Approach 1:
The patent uses a composite of epoxy compound and oxetane-based compound where the synergistic interaction between the two materials achieves high tensile modulus and storage modulus. This composite approach provides shrinkage resistance without requiring overly complex material structures.
Solution Approach 2:
By optimizing the ratio and selection of epoxy and oxetane-based compounds, the patent achieves the desired mechanical properties (high tensile modulus and storage modulus) with a relatively simple two-component composition, avoiding excessive complexity.
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 provides a thin, lightweight polarizing plate with high tensile modulus and storage modulus, effectively suppressing crack occurrences and light leakage, even without a separate protective film, ensuring excellent durability and adhesive strength for large-area liquid crystal display devices.
Implementation Method 1
the protective layer is a cured material of a photocurable composition for a polarizing plate protective layer comprising an epoxy compound and an oxetane-based compound
Implementation Method 2
a protective layer provided on one surface or both surfaces of the polarizer directly adjoining the polarizer
Data Source
Figure 1~5
Figure 6
AI summary
A polarizing plate is provided. The polarizing plate includes a polarizer; and a protective layer provided on one surface or both surfaces of the polarizer directly adjoining the polarizer, wherein the protective layer is a cured material of a photocurable composition for a polarizing plate protective layer comprising an epoxy compound and an oxetane-based compound, and an image display device comprising the polarizing plate.