Touch Panel Adhesive Composition High Molecular Weight Resin

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Solution Overview

Problem

Adhesives for touch panels face challenges with low heat resistance, leading to air pockets, bubbles, separation, and curling during high-temperature processes, and existing solutions fail to provide adequate durability and optical characteristics.

Innovation Solution

An adhesive composition comprising a base resin and a polyfunctional crosslinking agent, with a dynamic shear strength of 6 kg/cm² or more at 140°C, ensuring excellent heat resistance, wettability, and durability, and preventing panel warpage, separation, or curling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a low molecular weight oligomer is used to improve initial adhesion, then adhesion performance is improved, but heat resistance deteriorates causing air pockets and bubbles at high temperature

Engineering Contradiction:
Improveadhesion performanceVSAvoidheat resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent changes the molecular weight parameter of the base resin to 500,000-900,000, which is significantly higher than conventional oligomers. This parameter change fundamentally alters the thermal behavior of the adhesive, enabling it to maintain adhesion strength at high temperatures (140°C or higher) without generating air pockets or bubbles, while still providing sufficient initial adhesion performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite adhesive system by combining a high molecular weight base resin with a polyfunctional crosslinking agent. This composite structure provides both the initial adhesion properties needed for bonding and the heat resistance required to prevent separation and bubble formation during high-temperature curing processes (140°C or more).

Inventive Principle:
Principle #40Composite materials

2Reliability

If adhesive composition is cured at high temperature (140°C or more) to improve durability, then durability is improved, but low heat resistance adhesives cause separation and curls

Engineering Contradiction:
ImprovedurabilityVSAvoidadhesive stability at high temperature
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the molecular weight parameter of the base resin to 500,000-900,000, which fundamentally alters the thermal behavior of the adhesive. This high molecular weight configuration enables the adhesive to maintain its compositional stability at high curing temperatures (140°C or more), preventing separation, curls, and other degradation phenomena while achieving the desired durability through high-temperature curing.

Inventive Principle:
Principle #35Parameter changes

3Length of moving object

If base film thickness is reduced to achieve slimness, then device thickness is reduced, but breakage resistance deteriorates

Engineering Contradiction:
Improvedevice thicknessVSAvoidbreakage resistance
Core Design Contradiction:
Length of moving objectVSStrength

Solution Approach 1:

The patent employs a composite adhesive system combining high molecular weight base resin with polyfunctional crosslinking agent that creates a reinforced adhesive layer. This composite structure provides enhanced mechanical strength and breakage resistance to thin base films (50-200 μm), enabling the device to achieve slimness while maintaining adequate protection against breakage during handling and use.

Inventive Principle:
Principle #40Composite materials

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 adhesive composition exhibits superior heat resistance and durability, maintaining adhesion and optical properties under high-temperature conditions, preventing warpage, separation, and curling, while ensuring excellent cuttability and workability.

Implementation Method 1

an adhesive composition comprising a base resin and a polyfunctional crosslinking agent

Methodology Applied
Scientific EffectCrosslinking: Chemical Bonding

Implementation Method 2

excellent adhesion to various substrates

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP2557135B1Adhesive composition, adhesive sheet, and touch panel
Publication Date: 2014.11.05 LG HAUSYS LTD
  • EP2557135B1 patent drawingFigure 1~2
  • EP2557135B1 patent drawingFigure 3~5
  • EP2557135B1 patent drawing

AI summary

The present invention relates to an adhesive composition, to an adhesive sheet, and to a touch panel. The present invention provides an adhesive composition, particularly an adhesive composition for a touch panel, which is prepared without using a low molecular weight polymer as an additive. The adhesive composition, the adhesive sheet, and the touch panel of the present invention exhibit superior heat resistance in a hardening process, a printed circuit board assembly process, or the like, and have superior physical properties such as optical characteristics, wettability, cuttability, workability, anti-curling properties, and durability.