UV Resin Coating for Rare Earth Magnets With Homogeneous Inkjet Deposition

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Solution Overview

Problem

Existing methods for forming a coating film on rare earth magnets, such as Nd-Fe-B sintered magnets, are inefficient, costly, and result in non-homogeneous coatings that compromise corrosion resistance and insulation, leading to performance degradation in applications like electric motors.

Innovation Solution

A method using an inkjet system to apply droplets of UV-curable resin composition onto the magnet surface, followed by UV irradiation to cure the resin, ensuring homogeneous coating with controlled density and thickness, thereby enhancing corrosion resistance and insulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If spray coating is used to apply coating material, then the coating process can be performed, but a certain amount of coating material becomes loss without attaching to the object, limiting the increase in yield

Engineering Contradiction:
Improvecoating material lossVSAvoidcoating material yield
Core Design Contradiction:
Loss of substanceVSProductivity

Solution Approach 1:

The patent replaces the mechanical spray coating system with an inkjet printing system that uses digital control to deposit coating material. This substitution eliminates the inherent material loss of spray coating by precisely controlling the deposition process, allowing coating material to be applied only where needed and in exact amounts, thereby significantly reducing material loss and improving yield.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the deposition method from continuous spray to discrete droplet deposition controlled by digital parameters. By controlling the ejection of individual droplets based on digital signals, the system achieves precise material placement, reducing waste and improving coating material utilization efficiency.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If heating by heater is used to dry and bake the coating material, then the coating can be fixed, but it takes time and consumes high energy, and requires large equipment area

Engineering Contradiction:
Improvecoating fixationVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The patent replaces the thermal heating system with a UV irradiation system. Instead of using heat to dry and cure the coating material, UV light is used to initiate photopolymerization, rapidly curing the coating at room temperature. This substitution eliminates the need for energy-intensive heating equipment and reduces both energy consumption and equipment footprint while achieving reliable coating fixation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent utilizes the phase transition of UV-curable resin from liquid to solid through photopolymerization. By applying UV irradiation, the coating material undergoes a chemical phase change that rapidly cures the resin, providing immediate coating fixation without requiring thermal energy input or extended drying time.

Inventive Principle:
Principle #36Phase transitions

3Quantity of substance

If the magnet is immersed in UV-curable resin for coating, then the coating can be applied, but the excess resin is removed by rotation causing centrifugal force to form thick coating on the side away from rotation axis, making homogeneous coating difficult

Engineering Contradiction:
Improvecoating applicationVSAvoidcoating homogeneity
Core Design Contradiction:
Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical immersion and rotation method with a non-contact inkjet printing system. The inkjet system deposits UV-curable resin droplets directly onto the magnet surface according to digital patterns, eliminating the need for rotation and centrifugal force. This allows precise control of coating thickness and composition across the entire surface, achieving homogeneous coating without the defects caused by rotational methods.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent applies different amounts of coating material to different locations on the magnet surface based on digital control. The inkjet system can vary the droplet size, number, and placement according to the specific requirements of each area, ensuring optimal and homogeneous coating distribution across the entire surface rather than uniform rotation-based application.

Inventive Principle:
Principle #3Local quality

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 achieves a cost-effective, homogeneous coating film with improved corrosion resistance and insulation, reducing waste and energy consumption while maintaining the performance of the magnet in electric motor applications.

Implementation Method 1

attaching droplet of the UV-curable resin composition to the surface of the rare earth magnet with the ejection of the droplet from a tip of a head by an inkjet system of ejecting the droplet from the head

Methodology Applied
Scientific EffectInkjet ejection: Jet

Implementation Method 2

curing the UV-curable resin composition by irradiating the UV-curable resin composition attached onto the surface of the rare earth magnet with UV light

Methodology Applied
Scientific EffectUV curing: Photopolymerisation

Data Source

PatentEP3648132B1Method for forming coating film on rare earth magnet surface, and rare earth magnet
Publication Date: 2026.01.21 SHIN ETSU CHEMICAL CO LTD

AI summary

Provided is a rare earth magnet, on the surface of which a coating film of an ultraviolet cured resin is formed by covering the surface of the rare earth magnet with an ultraviolet curable resin composition and subsequently curing the ultraviolet curable resin composition by irradiating the ultraviolet curable resin composition with ultraviolet light. With respect to this rare earth magnet, the coating film is formed by a method which comprises: a step for having droplets of the ultraviolet curable resin composition adhere to the rare earth magnet surface by ejecting the droplets of the ultraviolet curable resin composition from a tip of a head by an inkjet method wherein droplets are ejected from a head; and a step for curing the ultraviolet curable resin composition by irradiating the ultraviolet curable resin composition adhering to the rare earth magnet surface with ultraviolet light.