Air Core Reactor Impregnation with Amine-Cured Epoxy
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Solution Overview
Problem
Current epoxy resin systems used for impregnating air core reactors are water-sensitive, prone to hydrolysis, and have weak crack resistance, leading to degradation and contamination issues, especially under temperature and humidity changes.
Innovation Solution
A process involving an impregnation system comprising epoxy groups, polypropylene or polyethylene glycols as flexibilizers, dicyandiamide, and imidazole or urea derivatives as accelerators, applied and cured at controlled temperatures to enhance hydrolysis and crack resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy-anhydride systems are used for impregnation, then good initial mechanical properties are achieved, but hydrolysis resistance deteriorates under high humidity and temperature
Solution Approach 1:
The patent changes the chemical parameters of the curing system by replacing anhydride curatives with amine-based curatives (dicyandiamide, imidazole derivatives, polyoxyalkylene polyamines). This fundamental parameter change transforms the chemical structure of the cured matrix to be inherently more resistant to hydrolysis while maintaining good mechanical properties, directly resolving the contradiction between initial strength and long-term hydrolysis resistance.
Solution Approach 2:
The patent creates a composite impregnation system combining epoxy resin with specific amine curatives and flexible extenders. This composite material system achieves both good mechanical properties from the epoxy network and enhanced hydrolysis resistance from the amine-based curing mechanism, eliminating the need to choose between strength and hydrolysis resistance.
2Strength
If anhydride-based epoxy systems are used, then adequate mechanical strength is achieved, but crack resistance deteriorates during temperature changes
Solution Approach 1:
The patent modifies the chemical composition parameters by introducing flexible extender chains (polyoxyalkylene structures) into the curing agent molecules. This parameter change creates a more flexible cured network that can accommodate thermal expansion and contraction stresses, thereby improving crack resistance during temperature cycles while maintaining mechanical strength.
Solution Approach 2:
The patent incorporates flexible extender molecules with polyoxyalkylene chains into the crosslinked network. These flexible molecular segments act as internal shock absorbers, allowing the cured matrix to flex and deform elastically during temperature changes without developing cracks, thus resolving the contradiction between strength and thermal stability.
3Manufacturing precision
If epoxy-anhydride systems are used in large chambers, then complete impregnation is achieved, but worker safety and hygiene deteriorate due to anhydride vapour contamination
Solution Approach 1:
The patent extracts and eliminates the harmful anhydride component from the impregnation system, replacing it with amine-based curatives that do not produce problematic vapors. This extraction of the harmful substance allows complete impregnation to be achieved without exposing workers to dangerous anhydride vapors, directly resolving the contradiction between manufacturing quality and worker safety.
Solution Approach 2:
The patent adopts amine-based curatives that can be applied at lower temperatures and shorter durations compared to anhydride systems. This reduces the need for large, expensive impregnation chambers and minimizes vapor generation during the shorter processing time, thereby improving worker safety while maintaining impregnation effectiveness.
4Strength
If epoxy resins are cured with acids and anhydrides, then good initial properties are achieved, but water sensitivity increases leading to matrix hydrolysis
Solution Approach 1:
The patent fundamentally changes the chemical parameter of the curing agent from acidic anhydrides to basic/amphoteric amines. This parameter change alters the chemistry of the crosslinked matrix to be inherently less susceptible to water attack and hydrolysis, while still achieving good initial mechanical properties through the epoxy-amine crosslinked network.
Solution Approach 2:
The patent converts the traditionally harmful effect of moisture on epoxy-anhydride systems into a beneficial feature by using amine-based curatives. The amine-cured matrix naturally resists hydrolysis, turning what was previously a degradation mechanism into a protective characteristic, thereby resolving the contradiction between initial strength and water sensitivity.
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 air core reactors with improved hydrolysis resistance and crack resistance, reducing the risk of degradation and contamination, and ensuring better performance under varying environmental conditions.
Implementation Method 1
Applying an impregnation system to the air core reactor or the part of the air core reactor wherein said impregnation system comprises a) one or more component(s) comprising one or more epoxy group(s), c) dicyandiamide; and curing the impregnated air core reactor
Implementation Method 2
one or more flexibilizer selected from polypropylene glycols or polyethylene glycols
Implementation Method 3
one or more accelerator selected from the group consisting of imidazole, imidazole derivatives, urea derivatives and mixtures thereof
Data Source
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AI summary
The invention relates to a process for the impregnation of air core reactors or parts of air core reactors and impregnated air core reactors or parts thereof obtainable by said process.