CN-122025326-A - Surface treatment method and application of bonded ferrite magnetic powder with high mechanical property

Abstract

The invention relates to the technical field of plastic magnetic materials, and more specifically discloses a surface treatment method and application of bonded ferrite magnetic powder with high mechanical properties, wherein the method comprises the steps of firstly premixing a first part of magnetic powder accounting for 25% of all the bonded ferrite magnetic powder with white carbon black accounting for 0.02% -0.10% of all the bonded ferrite magnetic powder, and then mixing with the rest 75% of bonded ferrite magnetic powder; and then spraying the composite coupling treatment solution containing the silane coupling agent, the hyperdispersant and the absolute ethyl alcohol on the surface of the magnetic powder, and drying to remove the absolute ethyl alcohol to obtain the bonded ferrite magnetic powder with the surface treated. The method can improve the dispersibility and compatibility of the magnetic powder in a plastic magnetic system, improve the fluidity and mechanical properties under the condition of high filling, and is suitable for preparing ferrite injection molding granules and ferrite plastic magnetic materials.

Inventors

• XIONG JUN
• WANG YONGQI
• WANG JIQUAN
• SUN WEI
• ZHANG PENGJIE

Assignees

• 北矿磁材（阜阳）有限公司

Dates

Publication Date

20260512

Application Date

20260319

Claims (10)

1. 1. The surface treatment method of the bonded ferrite magnetic powder with high mechanical property is characterized by comprising the following steps of: Step a, adding white carbon black and a first part of bonded ferrite magnetic powder into a high-speed mixer for premixing to obtain premixed magnetic powder, wherein the addition amount of the white carbon black is 0.02% -0.10% of the mass of all the bonded ferrite magnetic powder, and the first part of bonded ferrite magnetic powder accounts for 25% of the mass of all the bonded ferrite magnetic powder; Step b, mixing and stirring a second part of bonded ferrite magnetic powder with the premixed magnetic powder uniformly to obtain magnetic powder to be coupled, wherein the second part of bonded ferrite magnetic powder accounts for 75% of the mass of all the bonded ferrite magnetic powder; step c, uniformly mixing a silane coupling agent, a hyperdispersant and absolute ethyl alcohol to obtain a composite coupling treatment solution; D, placing the magnetic powder to be coupled into a high-speed mixer for rotation, and uniformly spraying the composite coupling treatment liquid onto the surface of the magnetic powder to be coupled through a spraying device so as to perform composite coupling treatment on the magnetic powder to be coupled; and e, discharging the magnetic powder treated in the step d, and then placing the magnetic powder in an oven for drying so as to volatilize and remove the absolute ethyl alcohol, thereby obtaining the bonded ferrite magnetic powder with the surface treated.
2. 2. A method of surface treating bonded ferrite magnetic powder according to claim 1, wherein the white carbon black is precipitated silica or fumed silica.
3. 3. The surface treatment method for bonded ferrite magnetic powder according to claim 1 or 2, wherein the addition amount of white carbon black is 0.05% by mass of the whole bonded ferrite magnetic powder, and when the whole bonded ferrite magnetic powder is 10000 g; The first part of the bonded ferrite magnetic powder in step a is 2500g, and the second part of the bonded ferrite magnetic powder in step b is 7500g.
4. 4. A method of surface treatment of bonded ferrite magnetic powder according to any one of claims 1 to 3, characterized in that the premixing time in step a is 4 to 6min and the mixing and stirring time in step b is 5 to 10min.
5. 5. A method of surface treating bonded ferrite magnetic powder according to any one of claims 1 to 4, wherein the silane coupling agent in step c is N- (β -aminoethyl) - γ -aminopropyl trimethoxysilane.
6. 6. A method of surface treating bonded ferrite magnetic powder according to any one of claims 1 to 5, wherein the hyperdispersant in step c is DISPERBYK-2163 or DISPERBYK-2164.
7. 7. The surface treatment method of bonded ferrite magnetic powder according to any one of claims 1 to 6, wherein the composite coupling treatment liquid in step c is formed by mixing 100ml of silane coupling agent, 20ml of hyperdispersant and 100ml of absolute ethyl alcohol when the total bonded ferrite magnetic powder is 10000 g.
8. 8. The method for surface treatment of bonded ferrite magnetic powder according to any one of claims 1 to 7, wherein the spraying device in the step d is a pneumatic spray gun or an atomizing nozzle, the composite coupling treatment time in the step d is 10min to 20min, and the drying condition in the step e is 90 ℃ and the time is 2h.
9. 9. Use of the surface-treated bonded ferrite powder produced by the surface treatment method of bonded ferrite powder according to any one of claims 1 to 8 in the preparation of ferrite injection molding pellets or ferrite plastic-magnetic materials, characterized in that the addition amount of the surface-treated bonded ferrite powder in a binder formulation system is 80% -95%, preferably 85% -93%, and the binder is one of polyamide 6, polyamide 12 and polyphenylene sulfide.
10. 10. A surface-treated bonded ferrite magnetic powder characterized in that the surface-treated bonded ferrite magnetic powder is produced by the bonded ferrite magnetic powder surface treatment method according to any one of claims 1 to 8, and the surface thereof is loaded with a composite treatment layer formed by a white carbon black, a silane coupling agent and a hyperdispersant together, and absolute ethyl alcohol is removed by baking.

Description

Surface treatment method and application of bonded ferrite magnetic powder with high mechanical property Technical Field The invention relates to the technical field of plastic magnetic materials, in particular to a surface treatment method and application of bonded ferrite magnetic powder with high mechanical properties. Background The ferrite plastic magnetic material is prepared through surface treatment of bonded ferrite magnetic powder, mixing with adhesive, lubricant and other assistant in certain proportion, double screw extrusion to pelletize to obtain injection molding granule, injection molding and magnetic field orientation. The material has the characteristics of one-step molding, high dimensional accuracy, suitability for preparing products with complex shapes and multipolar orientations, and the like, and is widely applied to the fields of micro-special motors, variable frequency household appliances, office equipment, automobiles and the like. However, as the micro-motor is advanced toward high performance, miniaturization and light weight, the plastic-magnetic material as a key raw material needs higher magnetic performance, and the improvement of magnetic performance is generally dependent on the improvement of the filling rate of magnetic powder. When the filling rate of the magnetic powder reaches more than 90%, although the magnetic performance can be improved, the tensile strength, the bending strength and the impact strength of the material can be obviously reduced due to the reduction of the binder ratio, and the plastic-magnetic product is easy to crack and deform in the injection molding process or the subsequent use process, thereby influencing the yield and the use reliability. Meanwhile, under the condition of high powder filling rate, the viscosity of the system is increased, the interaction among magnetic powder particles is enhanced, and the fluidity of injection molding granules is reduced. When the fluidity is too low, not only is higher injection pressure needed, but also the problems of insufficient mold filling, rough surface, internal air hole cavities, limited magnetic powder orientation, reduced surface magnetic flux and the like are easy to occur, so that the processing quality and magnetic performance of the plastic magnetic product are affected. In order to solve the above problems, the prior art generally improves the mechanical properties or the flowability of the material by reducing the content of magnetic powder, adjusting a nylon formula system or adding a lubricant. However, the reduction of the magnetic powder content can directly lead to the reduction of magnetic performance, the simple optimization of a nylon formula system still has difficulty in solving the problems of easy cracking and easy deformation of products under the condition of high powder filling rate, and partial additives have the problem of poor compatibility with ferrite magnetic powder and a high polymer binder, and are easy to precipitate, bloom, scale or react with other auxiliary agents. In addition, the existing surface treatment method of bonded ferrite magnetic powder generally adopts KH550 and absolute ethyl alcohol to treat the magnetic powder and dry the magnetic powder. Although KH550 is used as a silane coupling agent to treat a filler containing a large amount of silica or silicate, bonded ferrite magnetic powder does not contain a siliceous component, and it is difficult to sufficiently exert the coupling effect of the silane coupling agent, and on the other hand, white carbon black is useful for enhancing and improving dispersion, but is easy to agglomerate on the surface and insufficient in compatibility with an organic matrix, and if proper coupling and dispersion synergistic treatment is lacking, the effect exertion is also affected. Therefore, it is necessary to provide a new surface treatment method for bonded ferrite magnetic powder, which enables a small amount of white carbon black to be uniformly dispersed in the magnetic powder, and improves the dispersibility, compatibility and interfacial bonding capability of the magnetic powder in a plastic magnetic system through the compound coupling treatment of a silane coupling agent and a hyperdispersant, so that the mechanical property and the flow property are improved at the same time under the condition of higher filling rate of the magnetic powder. Disclosure of Invention In order to overcome the above-mentioned drawbacks of the prior art, embodiments of the present invention provide a method for surface treatment of bonded ferrite magnetic powder with high mechanical properties and application thereof, so as to solve the problems set forth in the background art. In order to achieve the above purpose, the invention provides a method for surface treatment of bonded ferrite magnetic powder with high mechanical properties, which comprises the following steps: Step a, adding white carbon black and a first part of bonded