Photocurable Resin Composition for Display Adhesion
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Solution Overview
Problem
Conventional methods for bonding image display members with light-transmitting cover members using photocurable resin compositions face issues with insufficient adhesion, peeling, and curing challenges, especially under high temperature and humidity conditions, due to incomplete curing and the need for dual polymerization processes.
Innovation Solution
A liquid photocurable resin composition containing a (meth)acrylate oligomer, an alkyl (meth)acrylate monomer, and a photopolymerization initiator with a specific ratio of molecule cleavage-type and hydrogen-abstracting photoradical polymerization initiators, which is cured using ultraviolet rays to achieve a high curing ratio and glass transition temperature suitable for maintaining adhesion and shape under various conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photocurable resin composition is used to bond image display members with light-transmitting cover members, then bonding and layering can be achieved, but insufficient curing occurs in the presence of light-shielding layers leading to poor adhesion
Solution Approach 1:
The patent changes the chemical parameters of the photocurable resin composition by incorporating specific monomers (acrylic acid, methacrylic acid) and controlling the molecular weight distribution of oligomers to enable effective curing despite the presence of light-shielding layers, achieving both complete curing and strong adhesion
2Reliability
If a thermal polymerization initiator is added to enable thermal curing, then adhesion can be improved, but facility investment and process complexity increase
Solution Approach 1:
The patent extracts and removes the thermal polymerization initiator from the composition, relying solely on photopolymerization with optimized photoinitiators and resin components that achieve both adequate curing and adhesion without requiring thermal processing facilities
Solution Approach 2:
The photocurable resin composition is designed to perform multiple functions simultaneously: providing adhesion, achieving complete curing, and maintaining flexibility, all through photopolymerization alone, eliminating the need for separate thermal curing systems
3Strength
If the composition is improved to enhance adhesion and bonding, then bonding strength increases, but the cured product becomes stiffened and loses flexibility
Solution Approach 1:
The patent creates a composite photocurable resin system combining specific ratios of acrylic oligomers (weight average molecular weight 1,000-100,000) with monomers containing carboxylic acid groups, achieving a balance between crosslinking density for adhesion and molecular mobility for flexibility
Solution Approach 2:
The patent optimizes the molecular weight parameter of the acrylic oligomer (1,000-100,000) and the compositional ratio of acid-containing monomers to achieve the desired balance between adhesion strength and cured product flexibility, preventing excessive stiffening
Data Source
Figure 1a~1c
Figure 1d~1e
Figure 1A~1D
AI summary
A liquid photocurable resin composition contains a (meth)acrylate oligomer component, an alkyl (meth)acrylate monomer component, and a photopolymerization initiator component. The (meth)acrylate oligomer component contains at least one oligomer selected from the group consisting of a polyurethane (meth)acrylate oligomer, a polyisoprene (meth)acrylate oligomer, a polybutadiene (meth)acrylate oligomer, and a polyether (meth)acrylate oligomer that have a weight average molecular weight of 1,000 to 200,000. The photopolymerization initiator contains a molecule cleavage-type photoradical polymerization initiator and a hydrogen-abstracting photoradical polymerization initiator at a ratio by mass of 10:1 to 10:35. The cured resin that is obtained by photoradical polymerization of the photocurable resin composition has a glass transition temperature of -40 to 20°C when the composition is cured at a curing ratio of the outermost surface of more than 90%.