Resin Composition Solvent Resistance Optical Layer

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Solution Overview

Problem

Resin compositions used for forming optical layers in cover members for moving bodies, such as automobiles, are prone to appearance impairment when exposed to petroleum-based solvents, leading to potential peeling of the protective layer from the base material.

Innovation Solution

A resin composition comprising a silicon-modified (meth)acryl resin, urethane (meth)acrylate, and polyfunctional (meth)acrylate, with a tetrafunctional (meth)acrylate content between 40 wt% and 70 wt%, applied as a second layer on a bisphenol-type polycarbonate-based resin, forming a protective layer with enhanced chemical resistance and adherence, even when exposed to petroleum-based solvents.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional coating layer is applied on a polycarbonate-based resin to provide weather fastness and scratch resistance, then the cover member can endure harsh environments, but the coating layer is prone to peeling and appearance impairment when exposed to petroleum-based solvents

Engineering Contradiction:

Improveweather fastness and environmental toleranceVSAvoidpeeling and appearance impairment from petroleum-based solvent exposure

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameters of the coating layer by specifying a resin composition containing silicon-modified (meth)acryl resin (5-20 wt%), urethane (meth)acrylate (10-30 wt%), and polyfunctional (meth)acrylate (65-80 wt%). This specific compositional parameter change provides resistance to petroleum-based solvents while maintaining weather fastness and scratch resistance

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite resin composition combining multiple types of (meth)acryl resins with specific functional properties. The silicon-modified component provides solvent resistance, the urethane component provides flexibility and adhesion, and the polyfunctional component provides crosslinking for enhanced durability, creating a composite material that resists both peeling and solvent damage

Inventive Principle:

Principle #40Composite materials

2Strength

If the coating layer is made harder to improve scratch resistance, then surface protection is enhanced, but the coating layer becomes more susceptible to peeling when exposed to chemicals

Engineering Contradiction:

Improvescratch resistanceVSAvoidadherence to base material under chemical exposure

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent balances hardness and adhesion by controlling the resin composition parameters, specifically using urethane (meth)acrylate (10-30 wt%) which provides flexible adhesion, and polyfunctional (meth)acrylate (65-80 wt%) which provides crosslinking density for hardness. This parameter balance ensures scratch resistance without sacrificing adherence under chemical exposure

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates different functional zones within the coating layer through the resin composition, where the silicon-modified (meth)acryl resin component provides localized solvent resistance, the urethane component provides localized adhesion to the base material, and the polyfunctional component provides localized hardness and crosslinking, achieving both scratch resistance and chemical resistance simultaneously

Inventive Principle:

Principle #3Local quality

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 resin composition ensures a protective layer with high adherence to the base material, preventing peeling and maintaining the optical layer's appearance and functionality despite exposure to chemicals, thereby enhancing the reliability of the moving body's cover member.

Implementation Method 1

the resin composition contains a silicon-modified (meth)acryl resin, a urethane (meth)acrylate, and a polyfunctional (meth)acrylate, wherein the polyfunctional (meth)acrylate contains a tetrafunctional (meth)acrylate

Methodology Applied

Scientific EffectCrosslinking: Chemical Bonding

Implementation Method 2

a visible light absorber which is dispersed in the resin material and absorbs visible light

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentEP3719085B1Resin composition, optical layer, cover member and movable body

Publication Date: 2022.10.26 SUMITOMO BAKELITE CO LTD

Figure 1~2

AI summary

A resin composition of the present invention is used for forming a second layer in an optical layer 10, contains a silicon-modified (meth)acryl resin, a urethane (meth)acrylate, and a polyfunctional (meth) acrylate, and satisfies the following condition A, in which the optical layer 10 includes a first layer (base material layer 1) containing a resin material and a visible light absorber and the second layer (protective layer 2) protecting the first layer. Condition A: In a case where the second layer is formed on a base material, a coating film of a mixed solvent containing a petroleum-based solvent at a proportion equal to or higher than 45 wt% is formed on the second layer and left as it is, and then the mixed solvent is removed, an adherence, which is determined by a cross-cut method, of the second layer cut in the form of a lattice with respect to the base material is equal to or higher than 95%.