Anti-Corrosive Lacquer for Rare Earth Magnets
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Solution Overview
Problem
Conventional lacquers fail to provide sufficient adhesive strength and insulation properties at high temperatures for rare earth permanent magnets, especially in segmented magnetic systems, and often result in faulty enamel sections due to air bubbles during the adhesion process.
Innovation Solution
A corrosion protection lacquer composition based on an epoxy resin mixture, an accelerator, and an epoxy-functional adhesive agent on a silane basis, which includes specific epoxy resins, phenol and cresol novolaks, and corrosion protection pigments, applied in a single processing step to ensure strong adhesion and insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If standard phenol-resin based lacquers with fillers are used, then corrosion protection is provided, but insulation properties are insufficient and brittleness develops at high temperatures
Solution Approach 1:
The patent uses a composite lacquer system combining phenol-resin base with specific epoxy resins (solid epoxy resin with epoxy number ≤2 Eq/kg and multi-functional epoxy resin with epoxy number >4 Eq/kg), corrosion protection pigments (zinc phosphate, zinc chromate, zinc hydroxyl phosphite), and non-metal fillers (silica dust, mica, talcum). This composite formulation provides simultaneous corrosion protection, electrical insulation, and high-temperature stability without brittleness.
2Strength
If standard epoxy resin lacquers are used, then good adhesion is achieved, but adhesive strength is insufficient at high temperatures
Solution Approach 1:
The patent modifies the chemical composition parameters of the lacquer by incorporating solid epoxy resin with low epoxy number (≤2 Eq/kg) and multi-functional epoxy resin with high epoxy number (>4 Eq/kg), along with phenol/cresol novolak. This parameter optimization enables the lacquer to maintain adhesive strength ≥10 N/mm² even at temperatures up to 180°C and during extended high-temperature aging.
3Object-affected harmful factors
If corrosion protection is applied after adhesion, then the magnets are protected from corrosion, but air bubbles cause faulty enamel sections
Solution Approach 1:
The patent merges the corrosion protection function and adhesion function into a single multi-functional lacquer coating. This unified approach eliminates the need for separate corrosion protection and adhesion steps, preventing air bubble entrapment that occurs when multiple layers are applied sequentially. The single coating process ensures both corrosion protection and high adhesion strength simultaneously.
4Manufacturing precision
If corrosion protection is applied before adhesion, then faulty enamel sections are avoided, but an additional processing step is required
Solution Approach 1:
The patent creates a universal lacquer composition that performs multiple functions simultaneously: it provides corrosion protection, ensures high adhesion strength, and delivers electrical insulation. This multi-functional coating eliminates the need for separate processing steps, maintaining manufacturing precision while significantly improving productivity by consolidating multiple operations into a single coating and curing step.
5Productivity
If a single processing step is used for both corrosion protection and adhesion, then productivity is improved, but existing lacquers cannot meet all requirements
Solution Approach 1:
The patent develops a composite lacquer system specifically formulated to meet all simultaneous requirements: adhesion strength ≥10 N/mm², electrical insulation, corrosion protection, and high-temperature resistance up to 180°C. The composite formulation includes optimized ratios of solid epoxy resin, multi-functional epoxy resin, phenol/cresol novolak, accelerators, and functional additives, enabling single-step processing that achieves full performance compliance.
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 lacquer composition achieves high adhesive strength, excellent insulation, and temperature resistance up to 150°C, with pressure resistance exceeding 10 N/mm² and no signs of corrosion or delamination, even under harsh conditions.
Implementation Method 1
an epoxy-functional adhesive agent based on silane
Implementation Method 2
based on an epoxy resin mixture
Data Source
AI summary
A paint composition, in particular an anti-corrosive paint, for rare earth permanent magnets, has an epoxy resin mixture, a curing accelerator, an epoxy-functional adhesion promoter based on silane and a solvent. Due to the paint compositions, rare earth permanent magnets can be bonded simultaneously to a magnet system in a one method step and can be protected against corrosion. Due to the anti-corrosive paint, magnet systems which have excellent anti-corrosion properties, a satisfactory adhesive strength even at high temperatures and display good electric insulation properties, are provided.