Ferrite Particles for Bonded Magnets with Controlled Density

Solution Overview

Problem

Current ferrite particles and resin compositions for bonded magnets fail to achieve high magnetic force, demagnetization resistance, and mechanical strength simultaneously, which are essential for advanced applications such as high-performance motors.

Innovation Solution

Ferrite particles with a bulk density of not more than 0.75 g/cm3 and a degree of compaction of not less than 65%, combined with a resin composition comprising 83 to 93% ferrite particles and 7 to 17% organic binder, including a silane coupling agent, to produce bonded magnets with enhanced magnetic properties and mechanical strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional ferrite particles with high bulk density are used, then packing density is improved, but tensile elongation and mechanical strength deteriorate

Engineering Contradiction:

Improvepacking densityVSAvoidtensile elongation

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The patent applies parameter changes by precisely controlling the bulk density of ferrite particles to 0.65-0.75 g/cm³ and degree of compaction to 60-70%, creating an optimal balance between packing density and mechanical strength. This parameter optimization resolves the contradiction by finding the sweet spot where both density and tensile elongation are satisfied

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by creating a multi-modal particle size distribution with specific proportions: 30-70% of particles in 0.5-2.0 μm range, 20-50% in 2.0-5.0 μm range, and 10-30% in 5.0-10.0 μm range. This local differentiation in particle sizes improves both packing efficiency and mechanical properties simultaneously

Inventive Principle:

Principle #3Local quality

2Force

If ferrite particles with small particle size are used, then magnetic properties are improved, but mechanical strength and demagnetization resistance deteriorate

Engineering Contradiction:

Improvemagnetic forceVSAvoidmechanical strength

Core Design Contradiction:

ForceVSStrength

Solution Approach 1:

The patent applies local quality by creating a multi-modal particle size distribution with specific proportions: 30-70% of particles in 0.5-2.0 μm range, 20-50% in 2.0-5.0 μm range, and 10-30% in 5.0-10.0 μm range. This local differentiation in particle sizes improves both packing efficiency and mechanical properties simultaneously

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies composite materials by combining ferrite particles with specific physical properties (bulk density 0.65-0.75 g/cm³, degree of compaction 60-70%) with an organic binder resin in a controlled ratio (93-70 wt% ferrite, 7-30 wt% binder). This composite structure achieves both high magnetic force and mechanical strength

Inventive Principle:

Principle #40Composite materials

3Force

If high ferrite content is used in resin composition, then magnetic properties are improved, but dispersibility and mechanical strength deteriorate

Engineering Contradiction:

Improvemagnetic forceVSAvoiddispersibility

Core Design Contradiction:

ForceVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by precisely controlling the bulk density of ferrite particles to 0.65-0.75 g/cm³ and degree of compaction to 60-70%, creating an optimal balance between packing density and mechanical strength. This parameter optimization resolves the contradiction by finding the sweet spot where both density and tensile elongation are satisfied

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by creating a multi-modal particle size distribution with specific proportions: 30-70% of particles in 0.5-2.0 μm range, 20-50% in 2.0-5.0 μm range, and 10-30% in 5.0-10.0 μm range. This local differentiation in particle sizes improves both packing efficiency and mechanical properties simultaneously

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9691528B2Ferrite particles for bonded magnets, resin composition for bonded magnets, and molded product using the same

Publication Date: 2017.06.27 TODA KOGYO CORP

AI summary

The present invention relates to ferrite particles for bonded magnets having a bulk density of not more than 0.75 g/cm3 and a degree of compaction of not less than 65%, a resin composition for bonded magnets using the ferrite particles and the composition, and a rotor. The ferrite particles for bonded magnets and the resin composition for bonded magnets according to the present invention are capable of providing a bonded magnet molded product having a good tensile elongation and an excellent magnetic properties.