Dual-Layer Hard Coat Resin Substrate Transparency
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Solution Overview
Problem
Conventional molded bodies with curable resin coatings lack sufficient surface hardness and abrasion resistance, failing to maintain surface characteristics after repeated wipes or usage.
Innovation Solution
A molded body with a resin substrate coated by a dual-layer hard coat system, where the first layer contains no inorganic particles and the second layer contains inorganic particles, achieving high transparency and enhanced hardness, with specific thickness and composition to ensure durability and designability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single-layer hard coat is applied to improve surface hardness, then abrasion resistance increases, but surface characteristics deteriorate after repeated wipes
Solution Approach 1:
The hard coat is divided into two distinct layers: a first hard coat layer containing inorganic particles for abrasion resistance, and a second hard coat layer without inorganic particles for surface characteristic maintenance. This segmentation allows each layer to specialize in one function, resolving the contradiction between hardness and durability of surface characteristics.
Solution Approach 2:
Different regions of the hard coat system have different compositions and properties. The first layer has high hardness through inorganic particles, while the second layer has superior surface characteristic retention. This local differentiation of material properties allows simultaneous optimization of both contradiction parameters.
2Strength
If inorganic particles are added to the hard coat to enhance hardness, then abrasion resistance improves, but light transmittance decreases
Solution Approach 1:
The hard coat system separates the function of light transmission to the second layer (free of inorganic particles) and the function of abrasion resistance to the first layer (containing inorganic particles). This functional segmentation allows both high light transmittance and high abrasion resistance to coexist.
Solution Approach 2:
The first hard coat layer acts as an intermediary between the substrate and the second hard coat layer. It provides abrasion resistance while allowing light to pass through to the second layer, which then provides the transparent surface finish. This intermediary structure resolves the contradiction between particle-containing and particle-free requirements.
3Illumination intensity
If the first hard coat layer is made thinner to maintain transparency, then light transmittance improves, but abrasion resistance may be compromised
Solution Approach 1:
The first hard coat layer uses a composite material system combining organic resin with inorganic particles, creating a material that provides maximum abrasion resistance in minimal thickness. The synergistic effect of the composite allows thinness for transparency while maintaining hardness for abrasion resistance.
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 dual-layer hard coat system significantly improves surface hardness and abrasion resistance, maintaining water-repellency and antifouling properties even after extensive use, making it suitable for applications in household and electronic devices.
Implementation Method 1
the hard coat comprises, from a surface layer side, a first hard coat layer and a second hard coat layer, the first hard coat is formed of a coating material containing no inorganic particles, the second hard coat is formed of a coating material containing inorganic particles
Implementation Method 2
the second hard coat is formed of a coating material containing inorganic particles
Implementation Method 3
a water contact angle at the first hard coat surface of 100° or more; and a water contact angle at the first hard coat surface after 20,000 reciprocating wipes with a cotton of 100° or more
Data Source
Figure 1(a)~2(c)
Figure 3(a)~4
AI summary
A molded body comprises a resin substrate, wherein a part or all of a surface of the substrate is coated with a hard coat, the hard coat comprises, from a surface layer side, a first hard coat layer and a second hard coat layer, the first hard coat is formed of a coating material containing no inorganic particles, the second hard coat is formed of a coating material containing inorganic particles, and the following (i) and (ii) are satisfied: (i) a total light transmittance of 85% or more; and (ii) a pencil hardness on the first hard coat surface of 5H or more.