Epoxy Resin Composition for Rotary Device Insulation
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Solution Overview
Problem
The existing curable epoxy resin compositions used for insulation in rotary devices face challenges with the miscibility of inorganic particles and epoxy resin, leading to aggregation and reduced heat resistance, which compromises insulation performance and dielectric breakdown strength.
Innovation Solution
A curable composition comprising a chain aliphatic epoxy resin with high aqueous dissolution rate, a cyclic or aromatic epoxy resin, and hydrophilic inorganic particles, which interact to prevent aggregation and enhance dispersibility without the need for a coupling agent, thereby improving heat resistance and insulation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic particles are dispersed in curable epoxy resin composition to improve dielectric breakdown strength, then insulation performance is improved, but inorganic particles aggregate and precipitate due to low miscibility, forming voids that reduce partial discharge resistance
Solution Approach 1:
A coupling agent is introduced as an intermediary substance between the inorganic particles and epoxy resin. The coupling agent has affinity to both the inorganic particle surface and the epoxy resin, acting as a bridge that improves interfacial adhesion and prevents particle aggregation. This mediator enables compatible interaction between the hydrophobic epoxy resin and hydrophilic inorganic particles without requiring them to be directly miscible.
Solution Approach 2:
The surface properties of inorganic particles are modified by changing parameters such as surface treatment, particle size distribution, and surface charge. By adjusting these parameters, the interfacial tension between particles and resin is reduced, preventing aggregation and improving long-term stability of the dispersion while maintaining dielectric breakdown strength enhancement.
2Stability of the object's composition
If a coupling agent is used to improve dispersibility of inorganic particles, then aggregation is reduced, but heat resistance of the cured product is reduced due to lower heat resistance of the coupling agent
Solution Approach 1:
The coupling agent is applied locally only at the interface between inorganic particles and epoxy resin, rather than throughout the entire bulk material. This localized application provides the necessary dispersibility improvement at critical interfaces while minimizing the overall concentration of heat-sensitive coupling agent in the cured product, thereby preserving bulk heat resistance properties.
Solution Approach 2:
Instead of using a large amount of coupling agent that would compromise heat resistance, a minimal surface coating or monolayer of coupling agent is applied to particle surfaces. This thin copied layer provides sufficient interfacial compatibility and dispersibility without significantly affecting the thermal properties of the bulk epoxy resin matrix.
3Stability of the object's composition
If coupling agent is dispersed in the cured product, then dispersibility of inorganic particles is improved, but dielectric breakdown may occur through the coupling agent due to inferior dielectric breakdown strength
Solution Approach 1:
The coupling agent is confined to thin interfacial layers at particle-resin boundaries rather than being distributed throughout the bulk. This localized positioning ensures that the coupling agent's inferior dielectric properties are restricted to minimal volumes at interfaces, while the bulk material maintains high dielectric breakdown strength through uniform epoxy resin and properly dispersed inorganic particles without continuous coupling agent pathways.
Solution Approach 2:
The harmful dielectric pathway created by coupling agent dispersion is eliminated by extracting or minimizing the coupling agent from the bulk material. Only the essential minimal surface treatment is retained at particle interfaces, removing the source of potential dielectric breakdown paths while preserving the necessary dispersibility function.
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 effectively suppresses aggregation of hydrophilic inorganic particles, maintaining heat resistance and enhancing insulation performance by ensuring uniform dispersion, thus improving the reliability of rotary devices.
Implementation Method 1
The first epoxy resin (a1) is a chain aliphatic epoxy resin having a hydrophilic group, and an aqueous dissolution rate of the first epoxy resin (a1) is not less than 20 mass % and not more than 99 mass %
Implementation Method 2
the inorganic particles are dispersed in the cured product, improvement of the dielectric breakdown strength can, for example, be expected
Data Source
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AI summary
A curable composition (X) includes: an epoxy resin (A); a curing agent (B); a curing promoter (C); and hydrophilic inorganic particles (D). The epoxy resin (A) includes a first epoxy resin (a1) and a second epoxy resin (a2). The first epoxy resin (a1) is a chain aliphatic epoxy resin having a hydrophilic group, and an aqueous dissolution rate of the first epoxy resin (a1) is not less than 20 mass % and not more than 99 mass %. The second epoxy resin (a2) includes at least one selected from the group consisting of a cyclic aliphatic epoxy resin, an aromatic epoxy resin and a heterocyclic epoxy resin.