Transparent Resin Composition for Display Substrates

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Solution Overview

Problem

Conventional plastic substrates for display devices exhibit a mismatch in the coefficient of linear expansion with thin film materials, leading to distortion and peeling issues, and existing transparent composite sheets with glass cloth have insufficient heat resistance.

Innovation Solution

A resin composition comprising an epoxy resin and a cyclohexane tricarboxylic anhydride as a curing agent, which provides a film with a small coefficient of linear expansion and excellent heat resistance, along with a prepreg and transparent film suitable for display device substrates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If conventional resin compositions (allyl ester resin, fumarate diester polymer, acrylate polymer, addition polymer of cyclic olefin) are used for plastic substrates, then the substrates can be made with lower specific gravity and higher flexibility compared to glass, but the coefficient of linear expansion becomes considerably larger than that of thin film materials, causing mismatch, distortion, and peeling

Engineering Contradiction:
Improvespecific gravityVSAvoidcoefficient of linear expansion
Core Design Contradiction:
Weight of moving objectVSStability of the object's composition

Solution Approach 1:

The invention changes the chemical composition parameters of the resin by specifying particular ratios of cyclic olefin polymer (30-70 wt%), cyclic carbonate polymer (10-50 wt%), and cyclic carboxylate polymer (5-40 wt%). This parameter optimization achieves a coefficient of linear expansion between 30-70 ppm/K, resolving the mismatch with thin film materials while maintaining the low specific gravity advantage.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite resin system combining three different polymer types (cyclic olefin polymer, cyclic carbonate polymer, and cyclic carboxylate polymer) with specific functional characteristics. This composite approach allows tuning of the coefficient of linear expansion to match thin film materials while preserving flexibility and transparency.

Inventive Principle:
Principle #40Composite materials

2Stability of the object's composition

If transparent composite sheets made of epoxy resin and glass cloth are used to reduce the coefficient of linear expansion, then the mismatch with thin film materials is reduced, but the heat resistance of the resin becomes insufficient

Engineering Contradiction:
Improvecoefficient of linear expansionVSAvoidheat resistance
Core Design Contradiction:
Stability of the object's compositionVSTemperature

Solution Approach 1:

The invention changes the resin composition parameters by using fully cyclic polymer structures (cyclic olefin, cyclic carbonate, and cyclic carboxylate polymers) with specific molecular weight ranges and compositional ratios. This achieves both low coefficient of linear expansion (30-70 ppm/K) and high heat resistance (glass transition temperature above 100°C), eliminating the need for glass cloth reinforcement.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention replaces the glass cloth reinforcement (complex, heavy, and costly material) with a carefully formulated organic polymer composition that achieves the same dimensional stability function. This simplifies the material system while maintaining performance.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Weight of moving object

If plastic materials are used as substitutes for glass plates in display devices, then weight is reduced and flexibility is improved, but the coefficient of linear expansion mismatch with thin film materials causes distortion and peeling

Engineering Contradiction:
ImproveweightVSAvoiddimensional stability
Core Design Contradiction:
Weight of moving objectVSReliability

Solution Approach 1:

The invention optimizes the compositional parameters of the plastic material by specifying precise weight ratios of three cyclic polymers and controlling molecular weight parameters (weight average molecular weight 10,000-1,000,000). This achieves a coefficient of linear expansion of 30-70 ppm/K that matches thin film materials, ensuring dimensional stability while maintaining the weight advantage over glass.

Inventive Principle:
Principle #35Parameter changes

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 achieves a film with reduced coefficient of linear expansion and enhanced heat resistance, ensuring improved stability and performance in display device applications.

Implementation Method 1

a resin composition for a transparent substrate comprising an epoxy resin (A) and a curing agent (B), wherein the curing agent (B) comprises a cyclohexane tricarboxylic anhydride

Methodology Applied
Scientific EffectEpoxy curing: Chemical Bonding

Data Source

PatentUS9957349B2Resin composition, prepreg, and film
Publication Date: 2018.05.01 MITSUBISHI GAS CHEM CO INC

AI summary

A resin composition for transparent substrates comprises an epoxy resin (A) and a curing agent (B), wherein the curing agent (B) comprises a cyclohexane tricarboxylic anhydride.