Double-Sided Optically Clear Adhesive for Touch Display Rework
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Solution Overview
Problem
Existing optically clear adhesives used in touch displays require strong adhesion, making panel rework processes difficult and environmentally unfriendly, as they are challenging to remove without damaging the polarizer and requiring significant manpower and solvents.
Innovation Solution
A double-sided optically clear adhesive with differentiated surface peel adhesion after low-temperature treatment, featuring a first and second adhesive layer with specific thermal-crosslinking agent ratios, allowing for easy peeling without residue on the polarizer, using monomers like hydroxyl group-containing and hydroxyl group-free hydrophilic monomers and (meth)acrylic acid alkyl esters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If strong adhesive force is used to bond panels, then panel bonding strength is improved, but panel reworkability deteriorates
Solution Approach 1:
The adhesive is divided into two distinct layers with different adhesive strengths: a first adhesive layer with strong adhesive force for initial panel bonding, and a second adhesive layer with weak adhesive force that allows easy peeling during rework. This segmentation enables the adhesive system to provide both strong bonding and easy reworkability simultaneously.
Solution Approach 2:
Different regions of the adhesive system are given different properties: the first adhesive layer (contacting the first substrate) has strong adhesion for secure bonding, while the second adhesive layer (contacting the second substrate) has weak adhesion for easy removal. This local differentiation of adhesive strength resolves the contradiction between strong bonding and easy reworkability.
2Strength
If strong adhesive force is used to bond panels, then panel bonding strength is improved, but environmental friendliness deteriorates due to solvent usage
Solution Approach 1:
The adhesive system is segmented into two layers with different functions: the first layer provides strong bonding, while the second layer is designed for easy removal without requiring solvents. This segmentation eliminates the need for harmful solvents during panel rework while maintaining strong initial bonding.
Solution Approach 2:
The weak adhesive layer, which might seem like a compromise in bonding strength, actually provides the benefit of solvent-free removal. By intentionally designing this layer with weaker adhesion, the patent converts what could be seen as a deficiency into an environmental advantage by eliminating solvent usage during rework.
3Strength
If strong adhesive force is used to bond panels, then panel bonding strength is improved, but peeling process complexity deteriorates
Solution Approach 1:
The adhesive is segmented into two layers with differentiated peeling characteristics. The first adhesive layer maintains strong bonding for panel assembly, while the second adhesive layer is designed to peel easily during rework. This segmentation simplifies the peeling process by eliminating the need for cutting machines or excessive manual intervention.
Solution Approach 2:
Instead of designing a uniformly strong adhesive that requires complex removal processes, the patent inverts the approach by designing a uniformly weak adhesive layer that peels easily. This inversion of the adhesive strength profile simplifies the peeling process while the first layer maintains necessary bonding strength.
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
Enables efficient peeling of touch display panels with reduced adhesion on the polarizer, minimizing residue and environmental impact, while maintaining sufficient adhesion on the glass for touch panel assembly.
Implementation Method 1
The first thermal-crosslinking agent includes a first group capable of reacting with the hydroxyl group of the first resin. The second thermal-crosslinking agent includes a second group capable of reacting with the hydroxyl group of the second resin.
Data Source
AI summary
A double-sided optically clear adhesive is provided. The double-sided optically clear adhesive includes a first adhesive layer and a second adhesive layer. The first adhesive layer includes a first resin and a first thermal-crosslinking agent. The first resin includes a hydroxyl group. The first thermal-crosslinking agent includes a first group. The second adhesive layer includes a second resin and a second thermal-crosslinking agent. The second resin includes a hydroxyl group. The second thermal-crosslinking agent includes a second group. The ratio of the equivalent number of the first group of the first thermal-crosslinking agent to the equivalent number of the hydroxyl group of the first resin is represented by r1. The ratio of the equivalent number of the second group of the second thermal-crosslinking agent to the equivalent number of the hydroxyl group of the second resin is represented by r2, wherein r1<r2≤0.8 and r2−r1≥0.025.