Electroconductive Laminate Hard Coat Layer Refractive Index Matching
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Solution Overview
Problem
Conventional electroconductive laminates face issues with adhesion between the hard coat layer and polycarbonate substrate, volatility of resin components during heat treatment, and the occurrence of interference fringes due to low molecular weight phenylphenol acrylate in the hard coating composition, which affects the crystallization of the transparent conductive film and visibility.
Innovation Solution
A hard coating composition comprising phenolic novolac acrylate, bisphenol structure-containing diacrylate, polyfunctional acrylate, and polyfunctional urethane acrylate is used, with specific ratios to form a hard coat layer on a polycarbonate substrate, eliminating volatile components and improving adhesion and refractive index, thereby preventing interference fringes and ensuring high visibility and stretchability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phenylphenol acrylate is used in the hard coating composition, then adhesion to polycarbonate substrate is improved, but volatile components are generated during heat treatment
Solution Approach 1:
The patent changes the molecular weight parameter of the phenylphenol acrylate from low (conventional) to high (1000-5000), which fundamentally alters the volatility characteristics while maintaining adhesion performance. This parameter change eliminates the harmful volatility effect during heat treatment while preserving the beneficial adhesion effect.
Solution Approach 2:
The patent replaces the low molecular weight phenylphenol acrylate (which has short-term stability but long-term volatility problems) with high molecular weight phenylphenol acrylate that provides stable, non-volatile performance throughout the product lifecycle.
2Reliability
If phenylphenol acrylate is used to improve adhesion, then cohesive failure is avoided in severe adhesion tests, but inhibition of crystallization of transparent conductive film occurs
Solution Approach 1:
By changing the molecular weight parameter from low to high, the patent reduces the inhibitory effect on crystallization while maintaining adhesion performance. The higher molecular weight reduces volatility and interference with the crystallization process of the transparent conductive film.
3Strength
If hard coat layer is applied onto polycarbonate substrate, then scratch resistance and durability are improved, but interference fringes appear
Solution Approach 1:
The patent changes the refractive index parameter of the hard coat layer to match that of the polycarbonate substrate. This parameter matching eliminates the interference fringes caused by refractive index differences, thereby improving visibility while maintaining the scratch resistance provided by the hard coat layer.
4Reliability
If low molecular weight phenylphenol acrylate is used, then adhesion is improved, but workability is lowered due to volatility during heat treatment
Solution Approach 1:
The patent changes the molecular weight parameter from low to high, which eliminates volatility during heat treatment processes. This parameter change improves workability by removing processing difficulties associated with volatile components while maintaining the adhesion benefits of phenylphenol acrylate.
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 an electroconductive laminate with excellent hardness, high visibility, and stretchability, preventing interference fringes and ensuring high adhesion even under severe testing conditions, while minimizing the inhibition of crystallization of the transparent conductive layer.
Implementation Method 1
a hard coat layer obtained by a hard coating composition comprising (A) a phenolic novolac acrylate having two or more acrylate groups, (B) a bisphenol structure-containing diacrylate having 2 to 4 moles of alkylene oxide structure
Implementation Method 2
the hard coat layer has a refractive index within a range of 1.535 to 1.545, thereby the hard coat layer has stretchability in addition to high visibility
Implementation Method 3
such phenylphenol acrylate is a mono-functional component having a low molecular weight. Thus, when a pyrolysis is generated, it may become a volatile component and it tends to inhibit a crystallization of the transparent conductive film
Implementation Method 4
such a component may improve an adhesion to the polycarbonate substrate which is often used as a substrate by an etching erosion of the polycarbonate substrate
Data Source
AI summary
The present invention is an electroconductive laminate characterized in that the hard coat layer is formed from a hard coating composition which contains (A) a phenolic novolac acrylate having two or more acrylate groups, (B) a bisphenol structure-containing diacrylate having 2 to 4 moles of alkylene oxide structure with two or three carbon atoms in each molecule, (C) a polyfunctional acrylate having three or more acrylate groups, and (D) a polyfunctional urethane acrylate having three or more acrylate groups and an ester structure.