Acrylate Adhesive Composition for Foldable Display Discharge Stability
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Solution Overview
Problem
Existing adhesive resins for flexible display devices face challenges in securing reliability during folding or bending operations and ensuring uniform discharge stability for various display shapes.
Innovation Solution
A resin composition comprising monofunctional and bifunctional (meth)acrylates with specific viscosity ranges and photoinitiators, which exhibit high adhesion properties and stable discharge rates, is used to form an adhesive member with a storage modulus and peel force suitable for flexible displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional adhesive resins are used, then the adhesive layer can be formed, but the discharge stability is poor and adhesion properties are insufficient during folding operations
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive resin by specifying exact proportions of monofunctional (meth)acrylates (80-90 wt%), bifunctional (meth)acrylates (10-20 wt%), and photoinitiators (1-5 wt%). This controlled parameter change achieves both excellent discharge stability (adhesion strength ≥800 gf/25mm) and reliable adhesion during folding operations by optimizing the molecular structure and crosslinking density of the cured adhesive.
Solution Approach 2:
The patent creates a composite adhesive system by combining multiple types of (meth)acrylates with different functional groups and molecular weights. The mixture of monofunctional and bifunctional (meth)acrylates provides both flowability for discharge stability and crosslinking capability for adhesion strength, resolving the contradiction between manufacturability and reliability.
2Strength
If the adhesive resin has high viscosity for good adhesion, then bonding strength improves, but discharge stability and uniformity deteriorate
Solution Approach 1:
The patent controls the viscosity parameter by selecting (meth)acrylates with specific molecular weight ranges and functional group ratios. The combination of lower molecular weight monofunctional (meth)acrylates (providing low viscosity for uniform discharge) with higher molecular weight bifunctional (meth)acrylates (providing strength after curing) achieves both discharge uniformity and adhesion strength simultaneously.
3Adaptability or versatility
If the adhesive layer is made flexible for folding operations, then bendability improves, but adhesion strength and reliability may decrease
Solution Approach 1:
The patent uses a composite formulation of monofunctional and bifunctional (meth)acrylates where the monofunctional components provide chain flexibility and the bifunctional components provide crosslinking strength. This composite structure enables the adhesive to maintain both flexibility for folding applications and sufficient adhesion strength (≥800 gf/25mm) after UV curing.
Solution Approach 2:
The patent creates a dynamic adhesive system that transitions from a liquid state (for application and folding flexibility) to a crosslinked gel state (for final adhesion strength). The photoinitiator system enables this dynamic transformation upon UV exposure, allowing the adhesive to adapt its properties based on operational requirements.
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 reliable adhesion and uniform discharge, maintaining stability during folding and unfolding, with high adhesion reliability and discharge stability, even after curing.
Implementation Method 1
at least one photoinitiator... after ultraviolet curing... providing light to the resin composition to form an adhesive member
Data Source
AI summary
A resin composition includes: at least two monofunctional (meth)acrylates, at least one bifunctional (meth)acrylate, and at least one photoinitiator. The resin composition has a shear viscosity of about 8 mPa·s to about 50 mPa·s as measured at a temperature of about 25° C. according to JIS Z8803, and an apparent extensional viscosity of about 100 mPa·s or less under conditions of the temperature of about 25° C. and a Hencky strain of about 6.