Optical Layered Body Hard Coat Segmentation
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Solution Overview
Problem
Existing optical layered bodies for image display devices face challenges in achieving hard coat properties, antistatic properties, and antireflection properties while avoiding interference fringes and cost inefficiencies due to the use of thick hard coat layers and high amounts of inorganic fine particles.
Innovation Solution
An optical layered body configuration featuring a light-transmitting substrate with a hard coat layer (A) and a hard coat layer (B) where layer (B) has regions with and without inorganic fine particles, with irregularities at their boundary, and the inorganic fine particles being conductive and smaller than visible light wavelengths, optimizing hardness and refractive index differences to prevent interference fringes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thick hard coat layer is produced to impart hard coat properties, then hard coat properties are improved, but the optical layered body is more likely to curl and pasting by rolling becomes difficult
Solution Approach 1:
The hard coat layer is divided into two distinct layers: a first hard coat layer containing inorganic fine particles and a second hard coat layer without inorganic fine particles. This segmentation allows each layer to serve specific functions - the first layer provides hardness while the second layer ensures smoothness for pasting, thereby resolving the contradiction between hard coat properties and ease of pasting.
2Strength
If a thick hard coat layer is produced to impart hard coat properties, then hard coat properties are improved, but the amount of inorganic fine particles increases causing cost disadvantage
Solution Approach 1:
Inorganic fine particles are localized only in the first hard coat layer rather than uniformly distributed throughout a thick single layer. The second hard coat layer is deliberately made without inorganic fine particles. This local quality approach provides necessary hardness where needed while minimizing the total quantity of expensive inorganic fine particles used.
3Strength
If inorganic fine particles are added to an upper layer to impart hard coat properties with a small amount, then hard coat properties are improved with low cost, but a refractive-index difference arises causing interference fringes
Solution Approach 1:
The patent segments the hard coat structure into two layers with different compositions. The first layer contains inorganic fine particles for hardness, while the second layer without particles provides optical uniformity. This segmentation prevents refractive-index differences from causing interference fringes by ensuring the outermost layer has consistent optical properties.
Solution Approach 2:
The patent changes the compositional parameter of the hard coat layers - specifically, the presence or absence of inorganic fine particles. By making the second layer particle-free, the refractive index becomes uniform throughout the outermost layer, eliminating the parameter variation that causes interference fringes while still maintaining hardness through the first layer.
Data Source
AI summary
The present invention provides an inexpensive optical layered body which does not cause interference fringes but excels in hard coat properties, antistatic properties, and antireflection properties.An optical layered body comprises: a light-transmitting substrate; and a hard coat layer (A) and a hard coat layer (B) on one face of the light-transmitting substrate in this order, wherein the hard coat layer (B) has a region (B1) not containing inorganic fine particles and a region (B2) containing inorganic fine particles, in this order from a portion adjacent to the hard coat layer (A), a boundary between the region (B1) not containing inorganic fine particles and the region (B2) containing inorganic fine particles has irregularities, and the inorganic fine particles have a particle size smaller than a visible light wavelength.