Stretchable Conductive Ink Composition for Stable Resistance
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Solution Overview
Problem
Existing conductive ink compositions fail to achieve sufficient elongation and maintain electrical conductivity when stretched, particularly in flexible electronic devices.
Innovation Solution
A conductive ink composition comprising a (meth)acrylic polymer with a glass transition temperature of 0° C. or less and a weight average molecular weight of 500,000 or more, combined with silver particles or carbon black, which have specific surface areas and particle diameters, to form an elastic conductive film suitable for stretched electronic devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conductive ink composition is used to form a flexible conductive film, then the film can be expanded and contracted, but the electrical resistance changes significantly during expansion and contraction
Solution Approach 1:
The patent changes the physical and chemical parameters of the binder polymer by selecting specific glass transition temperatures (−50°C to 0°C) and molecular weights (50,000 to 500,000), and by controlling the hydroxyl value (50-200 mgKOH/g). These parameter changes enable the binder to maintain optimal balance between flexibility and electrical conductivity stability during film expansion and contraction.
Solution Approach 2:
The patent uses a composite material system consisting of conductive filler particles (silver or carbon black) dispersed in a specially formulated binder polymer matrix. This composite structure allows the conductive network to remain stable while the binder provides the necessary flexibility, resolving the contradiction between adaptability and reliability.
2Strength
If the conductive film is made more elastic to accommodate stretching, then the elongation increases, but the electrical conductivity deteriorates
Solution Approach 1:
The patent optimizes the binder polymer parameters including glass transition temperature (−50°C to 0°C), molecular weight (50,000 to 500,000), and hydroxyl value (50-200 mgKOH/g). These parameter changes enable the film to achieve high elongation while maintaining electrical conductivity by ensuring the binder remains flexible yet maintains the conductive network integrity during stretching.
Solution Approach 2:
The patent creates local quality differentiation between the binder polymer and conductive filler particles. The binder provides localized flexibility and elasticity, while the conductive filler particles maintain the electrical conduction pathways. This local quality distribution allows the film to exhibit both high elongation and stable electrical conductivity simultaneously.
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 enables the formation of an elastic conductive film that maintains excellent electrical conductivity even after stretching, suitable for applications in flexible electronics and variable resistance sensors.
Implementation Method 1
a binder polymer and a conductive filler, wherein the binder polymer has a glass transition temperature of 0° C. or less, a weight average molecular weight of 500,000 or more, and a hydroxyl value of more than 50 mgKOH/g
Data Source
AI summary
A conductive ink composition contains a (meth)acrylic polymer (A) and silver particles (B). The (meth)acrylic polymer (A) has a glass transition temperature of ≤0° C., a weight average molecular weight of ≥500,000, and a hydroxyl value of more than 50 mgKOH/g. The silver particles (B) have a specific surface area of 0.5 to 3.0 m2/g, a 50% average particle diameter of 0.5 to 14.0 μm, a maximum particle diameter of ≥8 μm, and a solid content from 50 to 80% by mass. Another conductive ink composition contains a (meth)acrylic polymer (A) and carbon black (CB). The (meth)acrylic polymer (A) has a glass transition temperature of ≤0° C., a weight average molecular weight of ≥500,000, and a hydroxyl value of more than 50 mgKOH/g. The carbon black (CB) has a specific surface area of ≥50 m2/g, an aggregate diameter of ≤400 nm, and a solid content from 15 to 30% by mass.