Acryl-Thiol Adhesive Layer for Touch Panel Bubble Inhibition
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Solution Overview
Problem
Touch panels require a pressure-sensitive adhesive that maintains transparency under severe conditions, has high peel strength, inhibits bubble generation, and stabilizes conductor thin film resistance over time, especially when used with indium tin oxide (ITO) thin films.
Innovation Solution
A pressure-sensitive adhesive layer composed of an acryl polymer compound with a meth(acrylic) acid ester monomer and a thiol polymer, which provides a crosslinkable functional group, achieving a weight average molecular weight of 200,000 to 2,500,000 and a polydispersity index of 4.0 or more, ensuring high peel strength and minimal resistance change ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pressure-sensitive adhesive is used, then the touch panel can be assembled, but the adhesive layer generates bubbles and shows low peel strength under severe conditions
Solution Approach 1:
The patent changes the chemical composition parameters of the pressure-sensitive adhesive by incorporating specific functional groups (carboxyl, hydroxyl, amine, isocyanate, epoxy, or sulfone groups) into the polymer structure. This chemical modification enables crosslinking reactions that simultaneously improve cohesive strength (reducing bubbles) and adhesive strength (improving peel strength), resolving the contradiction between reliability and strength.
Solution Approach 2:
The patent creates a composite adhesive system by combining base polymers with crosslinking agents or functional monomers. The resulting composite material integrates the tackiness of the base polymer with the structural integrity provided by crosslinked networks, achieving both high peel strength and bubble generation inhibition through synergistic material composition.
2Device complexity
If the pressure-sensitive adhesive is directly adhered to ITO thin film, then assembly is simplified, but the resistance of conductor thin film changes over time
Solution Approach 1:
The patent introduces functional groups (carboxyl, hydroxyl, amine, isocyanate, epoxy, or sulfone groups) into the pressure-sensitive adhesive as intermediary chemical sites that can form stable bonds with ITO surfaces. These functional groups act as mediators between the adhesive and conductor, creating a stable interface that prevents resistance drift while maintaining direct adhesion, thus resolving the contradiction between assembly simplicity and resistance stability.
3Illumination intensity
If the pressure-sensitive adhesive maintains high transparency, then display quality is improved, but adhesion strength decreases under severe conditions
Solution Approach 1:
The patent modifies the chemical structure parameters of the adhesive by incorporating transparent polymer backbones with crosslinkable functional groups. The base polymer maintains optical transparency, while the functional groups enable crosslinking that enhances adhesion strength. This parameter change in molecular structure allows simultaneous achievement of high transparency and strong adhesion under severe conditions.
Solution Approach 2:
The patent creates a composite adhesive material combining transparent polymer matrices (maintaining optical properties) with crosslinking agents or functional monomers (providing strong adhesion). The composite structure separates the optical function (handled by transparent polymer) from the adhesive function (handled by crosslinked network), allowing both high transparency and strong adhesion to coexist.
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 layer effectively inhibits bubble generation and lift-off, maintains high peel strength, and stabilizes the resistance of ITO thin films, ensuring durable and long-term stable operation of touch panels under severe conditions.
Implementation Method 1
a thiol polymer derived from an acryl monomer and a thiol compound
Implementation Method 2
a copolymerizable monomer providing a crosslinkable functional group in a polymerized form
Data Source
Figure 1~3
Figure 4~5
AI summary
Provided is a touch panel. The touch panel includes a base and a pressure-sensitive adhesive layer attached to the base and having a peel strength with respect to a polycarbonate sheet of 1,900 g/25 mm or more. The pressure-sensitive adhesive layer includes an acryl polymer compound containing an acryl polymer and a thiol polymer derived by binding a thiol compound into a chain, or a side chain or terminal end of a chain of the acryl polymer. Accordingly, penetration of oxygen, moisture or other impurities at an interface between the base film and the pressure-sensitive adhesive layer, or at an interface between a conductor thin film and a pressure-sensitive adhesive layer may be effectively inhibited, and degradation in optical properties such as visibility due to bubbles generated at a pressure-sensitive adhesive interface may be prevented. In addition, when the pressure-sensitive adhesive layer is directly attached to the conductor thin film and even exposed to severe conditions such as high temperature or high temperature and high humidity, the change in the resistance of the conductor thin film may be effectively inhibited, and thus the touch panel may be stably driven for a long time.