Curable CNT Ink for Transparent Conductive Film Durability
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Solution Overview
Problem
Existing transparent conductive films (TCFs) using non-curable carbon nanotube (CNT) inks suffer from poor adhesion, abrasion resistance, and chemical resistance during the etching process, while maintaining electrical conductivity and high visible light transmission.
Innovation Solution
A curable carbon nanotube ink comprising a radiation-curable or thermally-curable resin binder, a catalyst, and a viscous diluent that fully evaporates during curing, which is used to create a transparent conductive film with improved adhesion, abrasion resistance, and chemical resistance, without the need for surfactants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If non-curable CNT inks are used, then the manufacturing process is simple, but the adhesion, abrasion resistance, and chemical resistance are poor
Solution Approach 1:
The patent changes the chemical state of the resin binder from non-curable to curable (UV or thermal), transforming the TCF from a simple coating to a crosslinked network structure. This parameter change enables the resin to form strong chemical bonds with the substrate and CNTs, dramatically improving adhesion, abrasion resistance, and chemical resistance during etching while maintaining electrical conductivity
Solution Approach 2:
The patent creates a composite material system consisting of curable resin binder, CNTs, and catalyst. The resin-CNT composite structure provides both mechanical strength (for adhesion and abrasion resistance) and electrical conductivity. The cured resin matrix protects the CNTs during chemical etching while maintaining the conductive network
2Stability of the object's composition
If surfactants are added to CNT dispersion, then the CNT remain dispersed, but the electronic properties deteriorate and require washing steps
Solution Approach 1:
The patent removes surfactants from the CNT ink formulation entirely. Instead of using surfactants to maintain dispersion, the invention relies on the viscous diluent to prevent CNT aggregation during storage and application. The curable resin binder then locks the CNTs in place upon curing, eliminating the need for surfactant washing steps and preserving electronic properties
Solution Approach 2:
The patent introduces a viscous diluent as an intermediary substance that mediates between CNTs and the resin binder. The diluent's high viscosity prevents CNTs from aggregating before curing, serving as a temporary dispersing medium that does not require removal. This intermediary enables stable CNT suspension without compromising electronic properties
3Stability of the object's composition
If the ink viscosity is increased to prevent CNT aggregation, then the CNT do not agglomerate, but the coating process becomes difficult
Solution Approach 1:
The patent optimizes the viscosity parameter of the diluent to a specific range that balances two opposing requirements: high enough to prevent CNT aggregation, but low enough to allow proper coating flow and screen printing. This controlled viscosity parameter enables both stable CNT suspension and ease of application
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 curable CNT ink results in TCFs with superior adhesion to metal-nanowire or metal mesh layers, enhanced abrasion and chemical resistance during etching, while maintaining excellent electrical conductivity and high visible light transmission.
Implementation Method 1
The ink includes one or both of a radiation-curable and a thermally-curable resin that acts as a binder for the CNT when the resin is cured
Implementation Method 2
The ink includes one or both of a radiation-curable and a thermally-curable resin that acts as a binder for the CNT when the resin is cured
Implementation Method 3
The ink also includes a viscous diluent that fully evaporates during the ink drying/curing process
Data Source
AI summary
A curable carbon nanotube ink and a transparent conductive film made using the ink. The ink includes a curable resin binder, a catalyst that is configured to be activated and cure the resin binder, a viscous to vapor diluent, and carbon nanotubes (CNTs). The CNT concentration range in the ink is from about 0.001% to about 0.2% by weight.