Epoxy Coating Composition for Heat-Resistant Laminated Cores
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Solution Overview
Problem
Existing laminated cores in electrical steel sheets experience stress strain and poor heat resistance, which deteriorate core iron loss and adhesion strength, especially in high-temperature applications like electric vehicle motors.
Innovation Solution
A coating composition for electrical steel sheets comprising an epoxy resin, a phenolic curing agent, and amine-based curing agents, with specific mass ratios, is applied to form an insulating coating that suppresses stress strain and maintains adhesion strength under heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the thickness of electrical steel sheet is decreased to reduce core iron loss, then core iron loss is reduced, but Young's modulus decreases making the sheet more susceptible to stress strain
Solution Approach 1:
The patent applies a composite coating system consisting of multiple layers: a base insulating coating layer and an overlay adhesive coating layer. This composite structure provides both mechanical reinforcement to compensate for the reduced strength of thin sheets and adequate insulation, allowing thin sheets to be used without excessive stress strain while maintaining low core iron loss.
Solution Approach 2:
The patent specifies precise compositional parameters for the coating materials, including the ratio of epoxy resin to curing agents (phenolic and amine-based) within specific ranges (e.g., epoxy resin:phenolic curing agent:amine-based curing agent = 100:1-40:0.5-5 parts by mass). These parameter optimizations ensure the coating provides sufficient mechanical support while maintaining electrical insulation properties.
2Stress or pressure
If soft insulating coatings are used to minimize stress strain on electrical steel sheets, then stress strain is reduced, but heat resistance and adhesion strength deteriorate
Solution Approach 1:
The patent employs a composite coating structure with two functional layers: a base insulating coating that minimizes stress strain on the steel sheet, and an adhesive coating layer containing epoxy resin with specific curing agents that provides high heat resistance and strong adhesion. This composite approach allows each layer to optimize its specific function without compromising the other.
Solution Approach 2:
Different regions of the coating system have different properties optimized for their specific functions. The base insulating coating layer is designed to be soft and compliant to minimize stress strain on the steel sheet surface, while the adhesive overlay layer is designed with high cross-linking density and thermal stability to provide heat resistance and adhesion strength at the bonding interface between laminated cores.
3Strength
If firm fixing methods such as swaging or welding are used to assemble laminated cores, then adhesion strength is improved, but mechanical strain or thermal strain is imparted to the laminated core deteriorating core iron loss
Solution Approach 1:
The patent replaces mechanical fixing methods (swaging) and thermal joining methods (welding) with a chemical adhesion system. The adhesive coating layer contains epoxy resin with phenolic and amine-based curing agents that form strong chemical bonds between laminated cores through curing, eliminating the need for mechanical deformation or thermal input that would otherwise cause strain and increase core iron loss.
Solution Approach 2:
The adhesive coating acts as an intermediary substance between the laminated cores, providing strong bonding through chemical adhesion without directly transmitting mechanical or thermal strain to the core. This intermediary layer absorbs and distributes stresses uniformly, preventing the concentration of strain that would occur with direct mechanical or thermal joining methods.
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 coating composition effectively reduces stress strain and enhances heat resistance, maintaining adhesion strength even during motor heat generation, thereby improving core iron loss and motor efficiency.
Implementation Method 1
a coating composition for an electrical steel sheet contains an epoxy resin, a phenolic curing agent (A) and one or more amine-based curing agents (B) selected from an aromatic amine and dicyandiamide
Implementation Method 2
the amount of the phenolic curing agent (A) is 1 to 40 parts by mass with respect to 100 parts by mass of the epoxy resin, and the amount of the amine-based curing agents (B) is 0.5 to 5 parts by mass with respect to 100 parts by mass of the epoxy resin
Implementation Method 3
capable of further suppressing stress strain that is imparted to electrical steel sheets
Implementation Method 4
have heat resistance high enough to maintain the adhesion strength even during the generation of heat from motors
Data Source
AI summary
This coating composition for an electrical steel sheet contains an epoxy resin, a phenolic curing agent (A) and one or more amine-based curing agents (B) selected from the group consisting of an aromatic amine and dicyandiamide, the amount of the phenolic curing agent (A) is 1 to 40 parts by mass with respect to 100 parts by mass of the epoxy resin, and the amount of the amine-based curing agents (B) is 0.5 to 5 parts by mass with respect to 100 parts by mass of the epoxy resin.