Hard Coat-Attached Film Touch Sensor with Dual-Layer Scratch Resistance
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Solution Overview
Problem
The manufacturing process of film-type touch sensors for flexible organic EL displays is hindered by the high scratch resistance of hard coat layers, leading to reduced workability due to defects like cracks, which are exacerbated by pressure and deformation during processing.
Innovation Solution
A hard coat-attached film type touch sensor is designed with a combination of a first hard coat layer of high hardness and a second hard coat layer of lower hardness, strategically positioned to prevent stress concentration and crack formation, while maintaining scratch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard coat layer of high hardness is provided on the outermost surface of the film type touch sensor, then scratch resistance is improved, but workability in manufacturing process deteriorates due to stress concentration and crack formation
Solution Approach 1:
The patent divides the hard coat layer into two distinct layers: a first hard coat layer with high hardness for scratch resistance, and a second hard coat layer with lower hardness for stress absorption. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between scratch resistance and manufacturing workability
Solution Approach 2:
The patent applies different hardness properties to different regions of the hard coat structure. The first hard coat layer has high hardness for scratch resistance, while the second hard coat layer has lower hardness specifically at the edge portions where stress concentration occurs during manufacturing. This local differentiation of material properties solves the contradiction by providing hardness only where needed for scratch resistance while maintaining flexibility at stress-prone areas
2Reliability
If a hard coat layer of high hardness is formed on the film type touch sensor, then surface protection is improved, but defects such as cracks are generated during outline processing due to stress concentration
Solution Approach 1:
The second hard coat layer with lower hardness is positioned at the edge portions before the manufacturing process occurs. This softer layer acts as a cushion that absorbs stress during outline processing such as punching, preventing stress concentration from reaching the first hard coat layer and causing cracks. This beforehand cushioning protects against defects while maintaining surface protection
3Manufacturing precision
If laser processing is used to avoid cracks during outline processing, then defect reduction is achieved, but production efficiency decreases and thermal damage occurs
Solution Approach 1:
The patent converts the potentially harmful high hardness of the first hard coat layer into a benefit by adding the second softer hard coat layer that specifically addresses the stress concentration problem. This allows the use of conventional mechanical processing methods like punching without requiring laser processing, thereby maintaining high production efficiency while eliminating defects. The second layer's lower hardness becomes beneficial by absorbing stress that would otherwise cause cracks
Data Source
AI summary
Provided is a hard coat-attached film type touch sensor excellent in workability in a manufacturing process while maintaining scratch resistance. A hard coat-attached film type touch sensor 1 used laminated on a display surface of a flexible display includes: a film type touch sensor 2; a first hard coat layer 4 provided in a large area on a region except for at least an edge portion 31 of one main surface of the film type touch sensor 2; and a second hard coat layer 5 provided adjacent to the first hard coat layer 4 in a region where the first hard coat layer 4 is not formed and having a lower hardness than the first hard coat layer 4.