Optical Laminate Hardness Matching for Polarizing Plate Crack Prevention
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Solution Overview
Problem
In the manufacturing of polarizing plates for image display devices, the removal of the front plate to reduce thickness leads to issues such as chipping of the masking layer and cracking between the masking layer and adjacent layers, compromising workability and leading to poor production outcomes.
Innovation Solution
An optical laminate configuration comprising a polarizer, an optical anisotropic layer, and a masking layer, where the hardness of the masking layer is between half to twice the hardness of the adjacent layer, improves workability and suppresses cracking during the production of polarizing plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the front plate is removed to reduce thickness, then the thickness of the optical member is reduced, but the masking layer chips and the surface becomes smoothed
Solution Approach 1:
The invention changes the physical parameter of hardness by specifying that the masking layer's hardness HB should be between 0.5 to 2.0 times the hardness HA of the adjacent layer. This parameter adjustment prevents chipping and surface smoothing while maintaining thickness reduction benefits.
Solution Approach 2:
The invention uses a composite structure with multiple layers (polarizer, optical anisotropic layer, and masking layer) where each layer has specifically controlled hardness properties. The masking layer is formulated as a composite material with appropriate hardness to prevent damage during handling and manufacturing.
2Length of moving object
If the masking layer is provided on the inner side of the polarizer, then thickness is reduced, but workability deteriorates and cracks occur between layers
Solution Approach 1:
The invention addresses the cracking issue by controlling the hardness parameter of the masking layer to be within 0.5 to 2.0 times the hardness of the adjacent optical anisotropic layer. This hardness matching prevents stress concentration and interlayer cracking during cutting and manufacturing processes.
Solution Approach 2:
The invention applies different hardness properties to different layers based on their specific functions. The masking layer is designed with localized hardness characteristics that balance protection and workability, while the optical anisotropic layer has its own optimized hardness for optical performance.
Data Source
AI summary
An object of the invention is to provide an optical laminate which has excellent workability in the production of a polarizing plate and is capable of suppressing the occurrence of cracks in the polarizing plate, a polarizing plate, a method of manufacturing the polarizing plate using the optical laminate, and an image display device having the polarizing plate. An optical laminate according to the invention has a polarizer, an optical anisotropic layer, and a masking layer in this order, and hardness HB of the masking layer and hardness HA of a layer adjacent to the optical anisotropic layer side of the masking layer satisfy Expression (1):HA×0.5≤HB≤HA×2 (1).