Silane-Treated Bonded Magnet Compound for Easier Injection Molding
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Solution Overview
Problem
Existing methods for producing bonded magnets face challenges such as increased viscosity during injection molding due to the use of small SmFeN particles, which affects fluidity and magnetic orientation, and the use of liquid epoxy resins results in poor fluidity and practical industrial difficulties.
Innovation Solution
A method involving coating magnetic materials with a thermosetting resin and a curing agent at a specific ratio, followed by granulation, milling, and surface treatment with a silane coupling agent, optionally including heat curing steps, to create a compound for bonded magnets that maintains mechanical strength and reduces viscosity during injection molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If SmFeN particles having a small size of 3 μm are used to produce a bonded magnet, then the filling ratio increases, but the viscosity of the compound increases during injection molding, causing difficulty in molding
Solution Approach 1:
The patent changes the particle size parameter from conventional small sizes (3 μm) to larger sizes (10-20 μm) to reduce compound viscosity and improve moldability, while compensating for the reduced filling ratio through optimized particle morphology and distribution to achieve high remanence
Solution Approach 2:
The patent applies preliminary surface treatment to the magnetic particles before compound formation to optimize their interaction with the resin matrix, enabling better flow characteristics during injection molding while maintaining effective magnetic coupling at larger particle sizes
2Ease of manufacture
If particles having a particle size much greater than 3 μm are used to increase fluidity in the resin, then the molding becomes easier, but the particles are not in a single domain state and have lower coercive force
Solution Approach 1:
The patent optimizes the particle size parameter to a specific range (10-20 μm) that balances fluidity requirements with magnetic performance, and controls the particle size distribution to ensure most particles remain in or near the single-domain state while achieving adequate flow characteristics
Solution Approach 2:
The patent applies different surface treatments or coatings to particles of different sizes within the distribution, optimizing local magnetic properties and resin interaction for each size group to maintain high coercive force while ensuring overall compound fluidity
3Strength
If a solid epoxy resin is used to consolidate magnetic particles, then the structure is mechanically strong, but the particles are inhibited from rotating and cannot show high orientation during molding in a magnetic field
Solution Approach 1:
The patent uses a thermosetting resin that transitions from a liquid state during injection molding (allowing particle rotation and high magnetic orientation) to a solid state after curing (providing mechanical strength), thus achieving both requirements through a dynamic state change
Solution Approach 2:
The patent exploits the phase transition of the thermosetting resin from liquid to solid through curing, enabling particles to rotate freely during the liquid injection and molding phase, then locking into their oriented positions with high mechanical strength after the solidification phase
4Reliability
If a liquid epoxy resin is used to allow particles to rotate easily for high orientation, then the magnetic properties improve, but the mixture has poor fluidity and is difficult to load into a compression molding machine
Solution Approach 1:
The patent optimizes the viscosity parameters of the liquid thermosetting resin and the particle size/distribution to achieve a balance where the mixture has sufficient fluidity for injection molding while still allowing particle rotation for high magnetic orientation
Solution Approach 2:
The patent applies preliminary surface treatment to the magnetic particles to reduce their agglomeration and improve the overall fluidity of the mixture, enabling easier loading into injection molding machines while maintaining the liquid state's benefit for particle rotation during molding
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 method improves remanence by allowing easy rotation of magnetic materials, enhancing orientation and filling ratios, resulting in higher magnetic properties and efficient production of bonded magnets.
Implementation Method 1
surface treating the milled product with a silane coupling agent
Implementation Method 2
heat curing the granulated product between the granulation and the milling, or including heat curing the milled product between the milling and the surface treatment
Data Source
AI summary
Included is a method of preparing a compound for bonded magnets, the method including: coating a magnetic material having an average particle size of 10 μm or less with a thermosetting resin and a curing agent at a ratio of the equivalent weight of the curing agent to the equivalent weight of the thermosetting resin of 2 or higher and 10 or lower to obtain a coated material; granulating the coated material by compression to obtain a granulated product; milling the granulated product to obtain a milled product; and surface treating the milled product with a silane coupling agent to obtain a compound for bonded magnets, the method either including, between the granulation and the milling, heat curing the granulated product to obtain a cured product, or including, between the milling and the surface treatment, heat curing the milled product to obtain a cured product.