Hard Coat Laminate With Carbon Gradient for Heat and Abrasion
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Solution Overview
Problem
Existing hard coat layers formed with sol-gel films containing inorganic nanoparticles face a trade-off between abrasion resistance and heat resistance due to increased internal distortion and stress concentration upon thermal cycling.
Innovation Solution
A hard coat laminate design with a base layer containing inorganic nanoparticles, where the compositional ratio of carbon atoms decreases from the substrate towards the surface, and a thin overcoat layer, enhances abrasion resistance while maintaining heat resistance by reducing internal distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the condensation rate of sol-gel film is increased to improve abrasion resistance, then the hardness of hard coat layer increases, but internal distortion increases causing stress concentration and peeling between hard coat layer and substrate during thermal cycles
Solution Approach 1:
The base layer is divided into multiple regions with different carbon compositional ratios. The first region (near substrate) has high carbon ratio (5-40 atom%) providing flexibility and stress distribution, while the second region (surface) has low carbon ratio (≤1 atom%) providing hardness and abrasion resistance. This segmentation resolves the contradiction by spatially separating the functional requirements.
Solution Approach 2:
Different regions of the base layer are given different compositional characteristics. The first region contains more carbon atoms (5-40 atom%) for stress absorption, while the second region contains less carbon atoms (≤1 atom%) for surface hardness. This local differentiation allows simultaneous achievement of both abrasion resistance and heat resistance.
2Reliability
If the compositional ratio of carbon atoms in base layer is increased to reduce internal distortion, then heat resistance improves, but abrasion resistance deteriorates
Solution Approach 1:
The base layer is segmented into first and second regions with different carbon compositional ratios. The first region (5-40 atom% C) handles thermal stress while the second region (≤1 atom% C) provides abrasion resistance, resolving the trade-off through spatial separation of functions.
Solution Approach 2:
The base layer exhibits local quality variation where the first region has high carbon content for heat resistance and the second region has low carbon content for abrasion resistance, allowing both properties to coexist in different locations.
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 laminate achieves improved abrasion resistance and heat resistance, with the base layer's first region having a carbon compositional ratio of 1 atom% or less and a hydrogen compositional ratio of 18 atom% or less, suppressing stress concentration and peeling, even under thermal cycles.
Implementation Method 1
the base layer has, on a surface side opposite to the substrate, a first region in which a compositional ratio of carbon atoms to all elements excluding hydrogen decreases as a distance from the substrate increases
Implementation Method 2
A siloxane bond is formed of the sol-gel film, whereby it is possible to improve the abrasion resistance as compared with an organic hard coat layer containing carbon as a main component
Implementation Method 3
since the sol-gel film can contain inorganic nanoparticles, it is possible to increase a hardness of the hard coat layer by containing the inorganic nanoparticles
Data Source
AI summary
Provided is a hard coat laminate having excellent abrasion resistance and heat resistance. The hard coat laminate includes: a substrate; and a base layer disposed on one main surface side of the substrate, in which the base layer contains inorganic nanoparticles, the base layer contains oxygen atoms, carbon atoms, and silicon atoms, the base layer has, on a surface side opposite to the substrate, a first region in which a compositional ratio of carbon atoms to all elements excluding hydrogen decreases as a distance from the substrate increases, in a region other than the first region of the base layer, a compositional ratio of carbon atoms to all elements excluding hydrogen is 5 atom % to 40 atom %, and a compositional ratio of carbon atoms on a surface of the first region is 1 atom % or less.