Conductive Polymer Composition for Solid Electrolytic Capacitors
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Solution Overview
Problem
Conductive polymer compositions with multiple undoped hydrophilic functional groups exhibit low water resistance and reliability issues, especially in high humidity environments, due to insufficient cross-linking and reaction limitations in existing methods using cross-linking compounds and silane coupling agents.
Innovation Solution
A conductive polymer composition is developed by condensing at least part of the hydrophilic groups of polyanions with an epoxy group in a conductive polymer suspension solution, using a compound with one epoxy group, which reacts and evaporates to enhance water resistance and conductivity, allowing the epoxy group to spread effectively into the polymer chain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive polymer composition is formed using a conductive polymer dispersion solution with polyanions as a dopant, then high conductivity is achieved, but water resistance deteriorates due to multiple undoped hydrophilic functional groups
Solution Approach 1:
The patent changes the chemical state of hydrophilic functional groups by reacting them with epoxy groups, transforming undoped hydrophilic groups into doped or cross-linked structures with reduced hydrophilicity, thereby improving water resistance while maintaining conductivity
Solution Approach 2:
The patent creates a composite structure by combining conductive polymer chains with polyanion dopants and epoxy group-containing compounds, forming a cross-linked network that simultaneously maintains electrical conductivity and improves water resistance
2Object-affected harmful factors
If cross-linking compounds with multiple functional groups are added to react with hydrophilic functional groups, then water resistance improves, but conductivity deteriorates due to steric hindrance blocking the conductive polymer chain
Solution Approach 1:
The patent uses a compound with a single epoxy group instead of multi-functional cross-linking compounds, allowing the epoxy group to penetrate and react with individual hydrophilic functional groups along the conductive polymer chain without creating steric hindrance that would block electron transport
Solution Approach 2:
The patent applies epoxy groups locally at the sites of hydrophilic functional groups along the conductive polymer chain, modifying only the specific regions that need water resistance improvement while preserving the overall conductivity of the polymer chain
3Object-affected harmful factors
If silane coupling agents are added to react with hydrophilic functional groups, then water resistance improves, but the reaction efficiency is insufficient due to limited spreading into the conductive polymer chain
Solution Approach 1:
The patent changes the molecular structure parameter by using a compound with a single epoxy group that has better penetration capability into the conductive polymer chain, allowing more effective reaction with hydrophilic functional groups compared to traditional silane coupling agents
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 resulting conductive polymer composition achieves high conductivity and excellent water resistance, leading to improved reliability and moisture resistance in solid electrolytic capacitors with low Equivalent Series Resistance (ESR).
Implementation Method 1
at least a part of the hydrophilic group of the polyanion is condensed with an epoxy group in a compound with one epoxy group
Implementation Method 2
a solvent in the conductive polymer suspension solution is evaporated
Data Source
AI summary
A conductive polymer composition with excellent water resistance and conductivity, and a solid electrolytic capacitor with low ESR, excellent reliability, and especially moisture resistance. The conductive polymer composition includes a conductive polymer, a polyanion that includes a hydrophilic group, where the polyanion functioning as a dopant of the conductive polymer. At least a part of the hydrophilic group of the polyanion is condensed with an epoxy group in a compound with one epoxy group. A solid electrolytic capacitor of the present invention includes the conductive polymer composition.