Double-Sided Adhesive Sheet for Touch Panel Displays

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Solution Overview

Problem

Conventional touch panel display devices suffer from visibility issues due to air gaps between the touch panel and the display device module, and existing double-sided adhesive sheets do not allow for easy separation and reattachment, leading to unnecessary discard of the display device module during repairs.

Innovation Solution

A double-sided adhesive sheet with a transparent acrylic resin layer and adhesive layers of different peeling strengths, where the first adhesive layer has a higher strength with the touch panel and the second adhesive layer has a lower strength with the display device module, ensuring secure bonding, improved visibility, and reworkability without leaving adhesive residue.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a conventional pressure-sensitive double-sided adhesive sheet is used to bond the touch panel directly to the display device module, then the air gap is eliminated and visibility is improved, but the display device module cannot be separated from the touch panel for repairs, causing it to be discarded

Engineering Contradiction:
ImprovevisibilityVSAvoidseparability for repair
Core Design Contradiction:
Illumination intensityVSEase of repair

Solution Approach 1:

The adhesive sheet is segmented into two distinct adhesive layers with different properties: a first adhesive layer with strong adhesion for permanent bonding, and a second adhesive layer with weak adhesion for easy separation. This segmentation allows the system to achieve both strong bonding for visibility improvement and easy separability for repairs.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the adhesive sheet have different local qualities - the first adhesive layer has high adhesion strength while the second adhesive layer has low adhesion strength. This local quality differentiation enables the dual functionality of permanent fixation and easy removal in different areas of the same adhesive sheet.

Inventive Principle:
Principle #3Local quality

2Strength

If a double-sided adhesive sheet with uniform adhesive strength is used, then the touch panel is securely bonded to the display device module, but the adhesive residue remains upon separation and the components cannot be reattached

Engineering Contradiction:
Improveadhesive strengthVSAvoidreworkability
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The adhesive sheet is divided into two functional segments: a first adhesive layer designed for strong bonding with high adhesion strength, and a second adhesive layer designed for easy separation with low adhesion strength. This segmentation resolves the contradiction between secure bonding and easy reworkability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of using uniform adhesive strength throughout, the invention inverts the approach by making one side strongly adhesive and the other side weakly adhesive. This inversion allows the adhesive sheet to provide both strong bonding capability and easy separation capability.

Inventive Principle:
Principle #13The other way round (Inversion)

3Strength

If the adhesive strength between the second adhesive layer and the display device module is high, then the bonding is secure, but the touch panel and display device module cannot be separated for repairs

Engineering Contradiction:
Improveadhesive strengthVSAvoidseparability
Core Design Contradiction:
StrengthVSEase of repair

Solution Approach 1:

The adhesive sheet exhibits different local qualities at its two surfaces: the first adhesive layer has high adhesion strength for secure bonding, while the second adhesive layer has low adhesion strength for easy separation. This local quality variation enables the system to achieve both secure bonding and easy repairability.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The adhesive system is segmented into two distinct layers with different adhesive strengths. The first layer provides strong bonding to the touch panel, while the second layer provides weak bonding to the display device module, enabling controlled separation for repairs.

Inventive Principle:
Principle #1Segmentation

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 eliminates air gaps, enhances visibility, and allows for the separation and reattachment of the touch panel and display device module, improving durability and usability while maintaining optical clarity.

Implementation Method 1

a first adhesive layer, a transparent acrylic resin layer and a second adhesive layer, wherein each of the first adhesive layer and the second adhesive layer includes an acrylic adhesive

Methodology Applied
Scientific EffectAdhesive: Adhesive

Implementation Method 2

adhesive strength between the first adhesive layer and the touch panel is higher than adhesive strength between the second adhesive layer and the display device module

Methodology Applied
Scientific EffectAdhesive: Adhesive

Data Source

PatentEP2644670B1Double-sided adhesive sheet and display device for touch panel including same
Publication Date: 2020.08.19 LG CHEM LTD
  • EP2644670B1 patent drawingFigure 1~3

AI summary

The embodiment examples of the present invention relate to a double-sided adhesive sheet and a display device for a touch panel including the same. The double-sided adhesive sheet, according to the embodiment examples of the present invention, comprises a transparent acryl-based resin layer as a substrate, can provide a double-sided adhesive sheet which can be detached and recycled after attaching to the touch panel and a display device module, by means of the adhesive agent layers that are formed on both sides having different detaching force, can improve visibility of the display device by being coupled between the touch panel and the display device module for eliminating an air gap, and can minimize the difference in the bending rate of each layer of the double-sided adhesive sheet for eliminating visibility exhaustion as much as possible.