Phenolic Polyurethane Conductive Paste for Stretchable Wire Stability
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Solution Overview
Problem
Existing wearable devices face challenges in maintaining stable electric conductivity during elongation and shrinkage, leading to reduced performance and potential device malfunction due to the limitations of current stretchable conductive materials.
Innovation Solution
A conductive paste composition containing a polyurethane with phenolic hydroxyl groups and a conductive filler, such as silver powder, which maintains electric conductivity and stability even during repetitive elongations and shrinkages, formed using a specific method that includes introducing phenolic hydroxyl groups and weakly acidic functional groups to enhance the polyurethane's properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional stretchable conductive materials are used in wearable devices, then the devices can be made flexible and stretchable, but the electric conductivity becomes unstable during elongation and shrinkage
Solution Approach 1:
The patent uses a composite material consisting of silver particles dispersed in a polyurethane matrix. The polyurethane provides stretchability while the silver particles maintain electrical conductivity. This composite structure resolves the contradiction by combining materials with complementary properties - the polymer matrix enables deformation while the conductive filler maintains electrical pathways during elongation and shrinkage.
2Reliability
If metal wire is used to ensure electric conductivity, then conductivity is maintained, but the wire lacks stretchability
Solution Approach 1:
The patent embeds conductive silver particles within a flexible polyurethane matrix, creating a composite that behaves like a flexible shell. This structure allows the material to be stretched and deformed unlike rigid metal wires, while the distributed silver particles maintain electrical conductivity throughout the deformation process.
Solution Approach 2:
By combining metal particles (silver) with a polymer matrix (polyurethane), the invention creates a composite material that exhibits both the electrical conductivity of metals and the flexibility/stretchability of polymers, directly resolving the contradiction between conductivity and stretchability.
3Adaptability or versatility
If conductive thread is woven to form patterns, then stretchability is achieved, but the pattern shape is limited and throughput is low
Solution Approach 1:
The patent replaces the mechanical weaving process with a printing process. Instead of physically weaving conductive threads into patterns, the conductive paste is printed directly onto the substrate. This substitution dramatically increases throughput and allows for complex patterns that would be difficult or impossible to create through weaving, while the underlying polyurethane-silver composite maintains stretchability.
4Productivity
If conductive paste is printed to form wires, then throughput is improved and pattern flexibility is enhanced, but electric conductivity varies during elongation
Solution Approach 1:
The patent optimizes several parameters of the conductive paste composition to maintain conductivity stability during elongation. This includes controlling the particle size distribution of silver particles, optimizing the polymer matrix composition and crosslinking density, and adjusting the volume fraction of conductive filler. These parameter changes ensure that the conductive network remains intact during deformation, maintaining stable electrical properties.
Solution Approach 2:
The specific composite formulation with optimized ratios of silver particles to polyurethane matrix ensures that the material maintains its conductive properties during printing and subsequent elongation, resolving the contradiction between improved throughput from printing and maintaining conductivity stability.
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 a conductive wire with stable electric conductivity and conduction stability during repetitive elongations and shrinkages, suitable for wearable devices, offering improved performance and durability.
Implementation Method 1
a conductive wire with stable electric conductivity and conduction stability during repetitive elongations and shrinkages
Data Source
AI summary
A polyurethane contains a phenolic hydroxyl group represented by the following general formula (1A). Thus, the present invention provides: a conductive paste composition for forming a stretchable conductive wire which varies slightly in electric conductivity at the time of elongation and shrinkage; and a polyurethane providing the composition.