Epoxy Resin Composition with Low Surface Tension for Conductive Adhesives
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Solution Overview
Problem
Existing epoxy resin compositions with low temperature curability also face issues of high initial viscosity and poor storage stability, especially when a large amount of conductive filler is added, leading to gelation and reduced storage stability.
Innovation Solution
An epoxy resin composition comprising an epoxy resin with two or more epoxy groups, an epoxy resin with a surface tension of 28.5 to 35.0 mN/m, a latent curing agent, and an electro-conductive filler, which maintains low initial viscosity and enhances storage stability while allowing for low temperature curability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a low molecular weight epoxy resin is used as a reactive diluent, then storage stability is improved, but initial viscosity becomes high (higher than 50 Pa·s)
Solution Approach 1:
The patent changes the surface tension parameter of the epoxy resin from conventional values to a specific range of 28.5-35.0 mN/m, which simultaneously achieves low initial viscosity (below 50 Pa·s) and excellent storage stability, resolving the contradiction between workability and storage stability
Solution Approach 2:
The patent uses a composite system comprising multiple components: epoxy resin (A), low molecular weight epoxy resin with specific surface tension (B), latent curing agent (C), and reaction inhibitor (D). This composite approach allows the composition to exhibit both low viscosity and high storage stability, which cannot be achieved with single components
2Reliability
If a large amount of electro-conductive filler is added to achieve electro-conductivity, then electrical conductivity is improved, but gelation proceeds and storage stability deteriorates
Solution Approach 1:
The low molecular weight epoxy resin (B) with specific surface tension acts as an intermediary that compatibilizes the electro-conductive filler particles with the epoxy resin matrix, preventing filler aggregation and gelation while maintaining electrical conductivity and storage stability
Solution Approach 2:
By controlling the surface tension parameter of component (B) within 28.5-35.0 mN/m and using a reaction inhibitor, the patent prevents premature gelation even with high filler content (400-2000 parts by mass per 100 parts of component (A)), maintaining both conductivity and storage stability
3Temperature
If conventional epoxy resin composition is used to achieve low temperature curability, then curability at low temperature is improved, but storage stability becomes poor
Solution Approach 1:
The patent uses a latent curing agent that remains inactive during storage and only activates at low curing temperatures (80-150°C). This preliminary design allows the composition to maintain storage stability while achieving low temperature curability when needed
Solution Approach 2:
The patent changes the chemical state parameter of the curing agent from active to latent form, which prevents premature reaction during storage but enables low temperature curing when activated, resolving the contradiction between storage stability and low temperature curability
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 excellent storage stability and low temperature curability with a low initial viscosity, preventing gelation and maintaining operational stability for extended periods.
Implementation Method 1
an epoxy resin composition including components (A) to (C): component (A): an epoxy resin (excluding the following component (B)); component (B): an epoxy resin having one epoxy group in a molecule and a surface tension of from 28.5 to 35.0 mN/m; and component (C): a latent curing agent
Data Source
AI summary
An epoxy resin composition which exhibits excellent storage stability while having a low initial viscosity and favorable low temperature curability and an electro-conductive adhesive containing the same. An epoxy resin composition includes components (A) to (C): component (A): an epoxy resin (excluding the following component (B)); component (B): an epoxy resin having one epoxy group in a molecule and a surface tension of from 28.5 to 35.0 mN/m; and component (C): a latent curing agent.