Conductive Silicone Composition for Solvent-Free Stretchable Printing
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Solution Overview
Problem
Existing electrically conductive silicone printing inks require high solvent content and significant amounts of carbon black with high surface area to achieve low resistance, which complicates printing processes and poses environmental and safety concerns, while lacking in variability and durability for stretchable applications.
Innovation Solution
A crosslinking silicone elastomer composition with a low BET surface area carbon black (≤300 m2/g) in small amounts (≤3% by weight) combined with CNTs, eliminating the need for solvents and achieving low viscosity, suitable for laser transfer printing and stretchable applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high surface area carbon black (BET >1400 m2/g) is used to achieve low electrical resistance, then conductivity is improved, but viscosity increases significantly making printing difficult
Solution Approach 1:
The patent changes the BET surface area parameter of carbon black from conventional high values (>1400 m2/g) to low values (50-300 m2/g). This parameter change reduces the viscosity increase effect while maintaining electrical conductivity when combined with CNTs, enabling both good printability and electrical performance
Solution Approach 2:
The patent creates a composite filler system combining CNTs (0.1-3 wt%) with low surface area carbon black (0.1-5 wt%). This composite approach leverages the high aspect ratio of CNTs for conductivity network formation and the lower viscosity contribution of low surface area carbon black, achieving both low resistance and good printability
2Ease of manufacture
If solvent is added to reduce viscosity for printing, then printability is improved, but environmental and safety concerns increase and additional removal steps are required
Solution Approach 1:
The patent extracts and eliminates the solvent component from the printing ink formulation. By using low surface area carbon black and optimizing the CNT content, the formulation achieves suitable viscosity for printing without requiring any solvent, thereby eliminating environmental and safety concerns associated with solvent use and removal
Solution Approach 2:
The patent replaces expensive and problematic solvent systems with a simple, solvent-free formulation. The low surface area carbon black and CNT combination provides the necessary rheological properties without requiring any additional solvent additives, simplifying the formulation and eliminating disposal concerns
3Reliability
If >20 wt% carbon black is used to achieve specific resistance below 100 Ωcm, then conductivity is improved, but the formulation becomes too viscous for practical printing applications
Solution Approach 1:
The patent dramatically changes the carbon black loading parameter from conventional high levels (>20 wt%) to low levels (0.1-5 wt%). This is made possible by using low surface area carbon black (50-300 m2/g) in combination with CNTs, which together provide sufficient conductivity without excessive viscosity increase
Solution Approach 2:
The patent uses a composite filler system where CNTs (0.1-3 wt%) work synergistically with low surface area carbon black (0.1-5 wt%). The CNTs provide conductive pathways at low loading, allowing minimal carbon black to be used, thus avoiding viscosity problems while achieving good conductivity
4Reliability
If thin CNTs (diameter <30 nm) are used to achieve good conductivity, then electrical properties are improved, but viscosity increases making screen printing impossible
Solution Approach 1:
The patent changes the CNT diameter parameter from thin (<30 nm) to thicker (30-100 nm). Thicker CNTs contribute less to viscosity increase while still providing effective conductive pathways when combined with low surface area carbon black, enabling screen printing 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 composition achieves a specific resistance of <10 Ohm*cm with reduced viscosity, enabling efficient printing of electrodes for dielectric elastomer sensors, actuators, and generators with minimal resistance increase during stretching, and is suitable for contactless printing processes.
Implementation Method 1
The printing ink described in U.S. Pat. No. 9,253,878 exhibits very good electrical conductivities... the conductivity of the electrode is improved
Implementation Method 2
A crosslinking silicone elastomer composition with a low BET surface area carbon black (≤300 m2/g) in small amounts (≤3% by weight) combined with CNTs, eliminating the need for solvents and achieving low viscosity
Implementation Method 3
a more homogeneous charge distribution in the electrode of the final component is ensured
Data Source
AI summary
An electrically conductive, crosslinking silicone elastomer composition is provided including carbon black in an amount of 0.5% to 3.0%, wherein the carbon black has a BET surface area of at most 300 m2/g. The electrically conductive, crosslinking silicone elastomer composition further includes carbon nanotubes (CNTs) in an amount of 0.1% to 3.0% by weight. The electrically conductive, crosslinking silicone elastomer composition does not include any solvent.