Non-crosslinked Thermoplastic Coating for Conductive Touch Screens
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Solution Overview
Problem
Current touch screen technologies face challenges with the fragility, limited supply, and low conductivity of Indium Tin Oxide (ITO) coatings, as well as issues with crosslinkable materials used in protective coatings, such as photoinitiators causing yellowing and adhesion problems.
Innovation Solution
A method involving a continuous polymeric web with photocurable compositions, electroless plating, and a non-crosslinked thermoplastic polymer coating is used to create electrically conductive patterns, eliminating the need for crosslinking and reducing post-processing complexity while maintaining high transparency and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crosslinkable materials (photocurable compositions) are used in protective coatings, then protection and durability are improved, but yellowing and adhesion problems occur due to photoinitiators
Solution Approach 1:
The patent removes photoinitiators and crosslinking agents from the protective coating formulation. The coating is applied as a photocurable composition but is deliberately left uncured, extracting the harmful crosslinking step while retaining the protective function of the coating layer.
Solution Approach 2:
Instead of curing the protective coating to achieve protection (conventional approach), the patent inverts the approach by applying the coating in photocurable form and intentionally leaving it uncured. The protection comes from the applied coating material itself rather than from crosslinked networks, eliminating the harmful byproducts of curing.
2Reliability
If Indium Tin Oxide (ITO) coatings are used for conductivity, then electrical conductivity is achieved, but fragility and limited supply become problems
Solution Approach 1:
The patent changes the material composition parameter from ITO to alternative electrically conductive materials such as metal particles (silver, aluminum, copper) or conductive polymers. This parameter change maintains electrical conductivity while improving flexibility and addressing supply limitations of ITO.
Solution Approach 2:
The patent employs composite structures combining transparent polymeric substrates with dispersed electrically conductive particles or conductive polymer layers. This composite approach achieves the required electrical conductivity through alternative mechanisms rather than relying on brittle ITO coatings.
3Reliability
If protective coatings are applied to protect electrically-conductive patterns, then environmental protection is improved, but manufacturing complexity increases due to crosslinking requirements
Solution Approach 1:
The patent extracts the crosslinking step from the manufacturing process. The protective coating is applied as a photocurable composition but the curing step is deliberately omitted, simplifying the manufacturing process while maintaining environmental protection through the applied coating layer.
Solution Approach 2:
The patent inverts the conventional manufacturing sequence where coating application is followed by curing. Instead, the coating is applied and deliberately left uncured, eliminating the complexity of crosslinking equipment and process control while achieving the protective function.
4Reliability
If ITO coatings are used in touch screens, then touch sensitivity is achieved, but flexibility and conductivity are limited
Solution Approach 1:
The patent changes the material parameters from rigid ITO coatings to flexible alternative conductive materials such as metal particle networks or conductive polymers. This enables the touch screen to maintain sensitivity while gaining flexibility and enhanced electrical conductivity.
Solution Approach 2:
The patent employs composite structures with transparent substrates and dispersed conductive elements that provide both flexibility and conductivity. The composite nature allows the material to bend and flex while maintaining electrical pathways for touch sensitivity.
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 provides improved protection and conductivity for touch screen sensors without the drawbacks of crosslinkable materials, ensuring durability and efficiency in manufacturing and integration.
Implementation Method 1
The photocurable composition is applied to a transparent substrate in a patternwise fashion to form a photocurable pattern thereon. The photocurable pattern is then exposed to UV or visible light to effect photopolymerization and thereby form a photocured pattern.
Implementation Method 2
The photocured pattern is electrolessly plated with an electrically-conductive metal to form an electrically-conductive metal pattern.
Data Source
AI summary
A method is used to provide an electrically conductive article. The method includes: (i) providing a continuous polymeric web of a transparent polymeric substrate; (ii) forming a first photocurable pattern on at least a first portion on a first supporting side of the continuous polymeric web using a photocurable composition comprising metal particles; (iii) exposing the photocurable pattern to form a photocured pattern on the first portion of the first supporting side; (iv) electrolessly plating the photocured pattern with an electrically-conductive metal to form an electrically-conductive metal pattern; and (v) forming a dry outermost polymeric coating over at least part but not all of the electrically-conductive pattern, the dry polymeric coating having a dry thickness of less than 5 μm, an integrated transmittance of at least 80%, and comprising a non-crosslinked thermoplastic polymer having a glass transition temperature (Tg) that is equal to or greater than 65° C.