JPS59135705A - Resin magnet material - Google Patents

Abstract

PURPOSE:To obtain an anisotropic resin magnet with excellent magnetic characteristics by mixing ferrite powder composed of a mixture of ferrite fine powder of average particle diameter 0.5-1.5mum and ferrite coarse powder of average particle diameter 30-250mum and synthetic resin. CONSTITUTION:Hard ferrite powder, such as barium ferrite and strontium ferrite, and their mixture are used as ferrite powder. Powder of average particle diameter 0.5-1.5mum is usually used as fine powder and especially a single magnetic domain particle is preferable. Powder of average particle diameter 30- 250mum is usually used as coarse powder and especially a multiple magnetic domain particle, whose average diameter is 100-200mum and which is oriented to one direction, is preferable. The mixing ratio of the fine powder and the coarse powder is usually in the range of 1:0.4-1:4 by weight ratio but especially the range of 1:0.7-1:1.2 is preferable. 88-96wt% of the ferrite and 12-4wt% of resin are mixed and pellet whose diameter is around 3mm. is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin magnet material from which an anisotropic z1] S light (81 fat magnet) which is excellent in magnetic properties and has little magnetic variation is easily obtained.

In recent years, so-called resin magnets and rubber magnets, which are made of mixtures of T-light powder, rare earth powder, etc. and synthetic resin, have become highly accurate even in complex or thin shapes without post-processing. Due to its characteristics, it has come to dominate the magnet market. However, the maximum energy product ([11
1) max = 1.2~1,7 MG ・Oe, and (BH) of the anisotropic sintered magnet may = 2.5~
4,5 It is lower than MG・Oe, and isotropic sintered magnet has (BH) max-=0.9~1.2 MG・Oe
Therefore, it is possible to replace it magnetically, but 2. Since isotropic sintered magnets are inexpensive, the market for more expensive wood MFI magnets and rubber magnets is currently limited. Resin magnet materials from which magnets can be easily obtained are strongly desired.

Regarding the method of obtaining resin magnets with excellent magnetic properties, single magnetic domain particles with an average particle size of up to 2 μm and particles with an average particle size of 300 to 100 μm are used.
There is a method for manufacturing an anisotropic permanent magnet (JP-A-56-3693) in which the filling rate for resin is improved by mixing a sintered semi-finished product or a sintered pulverized product with a diameter of 0 μm. However, in this method, the particle size of the sintered semi-finished product is 30
Since the magnets are large (0 to 1000 μm), complex, thin-walled anisotropic resin magnets cannot sufficiently orient the i′11 molecules, making it difficult to obtain excellent magnetic properties. In resin magnets for stepping motors and the like, variations in surface magnetic flux density and the like between magnetic poles (hereinafter referred to as magnetic variations) become large, making it impossible to obtain stable products. In addition, when molding complex, thin-walled magnets using injection molding methods or molding with bincate molds, particles tend to get clogged.
Continues stable molding and is difficult to peel.

The inventors of the present invention have made extensive studies in order to solve the problems described in 4.
As a result of market analysis, ferrite with an average particle size of 0.5 to 1.5 μm]
・When using a mixture of fine powder and coarse ferrite powder with an average particle size of 30 to 250 μm, the filling rate of the ferrite powder is higher than that of the above method (Japanese Patent Application Laid-Open No. 56-3693). Although the rate is slightly lower, even the resin magnet in the core is complex and oriented at 1°, and excellent magnetic properties can be obtained.
? It was discovered that an F-magnetized resin magnet has extremely small magnetic fluctuations, no clogging of particles during injection molding, and anisotropic tree BF1 magnets with excellent durability were obtained, leading to the completion of the present invention.

That is, in the present invention, the average particle size is 0.5~], 577 m
Ferrite powder 88 is a mixture of ferrite fine powder (hereinafter simply referred to as fine powder) and ferrite phase powder (hereinafter simply referred to as coarse powder) with an average particle size of 30 to 250 μm in an iI weight ratio of 10.4 to 1:4. ~96% weight and synthetic resin 12~
4M411 characterized by being formed by mixing 4% by weight with
M provides magnetic materials.

Examples of the 7-elite powder used in the present invention include hard ferite powders such as barium ferrite and strontium ferrite, and mixtures thereof, regardless of fine powder or coarse powder.

As the fine powder, powder having an average particle size of 0.5 to 1.5 m is usually used, and single Tit E particles are particularly preferred.

As the coarse powder, a powder having an average particle size of 30 to 250 μm is usually used, and among them, multi-domain particles blended in one direction and having an average particle size of 100 to 200 μm are preferable. Incidentally, the coarse powder used here is usually a powder obtained by pulverizing an anisotropic sintered magnet with a pulverizer such as a J1-Lee, a J9-Kushi Sosha, a hammer mill, a ball mill, a roll mill, a vibration mill, etc.
Of course, sintered magnets with an average particle size of 30 to 250 μm may be used as they are. Among these, preferable coarse powder has a residual magnetic flux density of 11r=3800 G or more and a coercive force bllc of -23
000e or more, intrinsic coercive force 1llc = 25000e
Above, maximum energy M (BH) max = 3.
This is a powder obtained by crushing and annealing an anisotropic sintered magnet of 8 MG Oe or higher.

If the average particle size of the coarse powder is less than 30 μm, the orientation of the powder is good, but a significant improvement in the filling rate cannot be expected, so a resin magnet with excellent magnetic properties cannot be obtained. However, since the powder cannot be oriented sufficiently, it is difficult to obtain a resin magnet with excellent magnetic properties, and the obtained tree Jll? The magnetic variation of the magnet increases,
Undesirable.

The mixing ratio of powder and coarse powder is usually the weight ratio]:
(The range is from 1,4 to 1:4, but especially t2o,
7~]: In the range of 2, particularly high filling and high orientation can be expected, so it is preferable.

Further, the ferrite powder (fine powder and coarse powder) used in the present invention may be surface-treated using a conventionally known silane thread, titanium-based surface treatment agent wire, or the like. Surface treatment may be performed on fine powders and coarse powders individually or after mixing them.
It may be carried out in the presence of a synthetic resin or other additives.

In addition, the direction of magnetic properties can be measured by using rare earth magnet powder, soft tubolite powder, magnetic iron powder, etc. instead of the hard fluorite powder described in nII. Powder and coarse powder of 30 to 250 μm are used, but it must be noted that fine powder is easily oxidized.

The synthetic resin used in the present invention °C is polyethylene, polypropylene, polystyrene, ethylene-vinyl acetate copolymer, ethylene glycol acrylate, 6-nylon,
Thermoplastic resins such as 6,6-nylon, 6.1 (+-nylon, 11-nylon, 12-nylon, polyamide for hot melt, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide), polyethylene wax, paraffin wax wax, epoxy resin M11, phenol resin, diallyl phthalate 4M resin, and other thermosetting resins, but thermoplastic resins are preferred because they can be produced by injection molding.
Among them, ethylene-vinyl acetate copolymer, ethylene ethyl acrylate, nylon, polyamide for bot-melt, and polyphenylene sulfide are preferred from the viewpoint of excellent moldability and mechanical strength, and 6-nylon is particularly preferred.

The synthetic resin may be in the form of powder, beads, or pellets, but powder that can be easily mixed uniformly with ferrite powder is preferred.

The resin magnet material of the present invention is prepared by combining 88 to 96 11a% ferrite powder, which is usually a mixture of fine powder and coarse powder in a predetermined ratio, and 12 to 4% by weight of synthetic resin in a ribbon flender, tumbler, Henschel mixer, Nauta mixer, etc. It is obtained by mixing in a mixer, but conventionally known additives such as surface treatment agents, lubricants, stabilizers, etc. can also be added. still,
The order in which the fine powder, In powder, synthetic resin, and additives are mixed is not particularly limited.

Next, the obtained composite magnetic material is passed through a Banbury mixer.
It is preferable to knead the mixture for 4 minutes using a kneader, a kneader-rouge, a roll, a Henschel mixer, a super mixer, a single-screw or multi-screw press, and then pelletize it to a particle size of about 31 mm.

The tree JI of the present invention thus obtained! ′? The maximum energy product (Bll) of the magnetic material is obtained by molding it in a magnetic field using an extrusion molding machine, injection molding machine, compression molding machine, etc.
An anisotropic resin magnet can be obtained which has excellent magnetic properties of max-1°8MG·0 (X or higher) and has extremely small variations in magnetic properties.

The present invention will be explained in detail below with reference to Examples. ,
Note that all parts in the examples are parts by weight.

Example 1 Anisotropic sintered strondium fluorite magnet [residual magnetic flux density Br'' 4200 G, coercive force BTLC = 270
00e, intrinsic coercive force 111c = 28000e, maximum energy m (Bll) max = 4.2MG-
Oe) was pulverized using a press-cranosher and a vibration mill, and then annealed at 950°C for 1 hour using an electric furnace to obtain stronch:j, umferite coarse powder with an average particle size of 100/Jm.

46 parts of the obtained strontium ferrite coarse powder and 2 pm of strontium ferrite coarse powder (average particle size), 46 parts of strontium ferrite fine powder (○P-11 manufactured by Nippon Braka Co., Ltd.) were placed in a Henschel mixer. 0.55 part of γ-aminopropyltriethoxysilane was sprayed and added while stirring and mixing at -, and the reaction was completed by heating to 120°C with further stirring. At the same time, the by-product ethyl alcohol was removed. After obtaining surface-treated strontium ferrite powder, 8 parts of powdered [5=nylon] was added and further mixed in a Henschel mixer to obtain a resin magnet material of the present invention. Next, it was kneaded at 270°C in a twin-screw extruder and pelletized to a particle size of 3.
A pellet-shaped resin magnet material III was obtained.

This was injection molded in a magnetic field of 120,000e (molding temperature 2
A cylindrical resin magnet with a diameter of 20 mm and a length of 1''l and 7 mm was obtained.The obtained magnet had a maximum energy product (
Bit) m,'Ix =2.05MG-Oe, which was excellent.

Example 2 37 parts of strontium ferrite fine powder with an average te diameter of 1.2 μm and an average particle diameter of 100 μT as ferrite powder
An I4 fat magnet material of the present invention was obtained in exactly the same manner as in Example 1 except that 55.5 parts of strondium fluorite coarse powder of n was used and 7.5 parts of 6-nylon was used as the synthetic resin. Then, it was pelletized and injection molded in the same way to make pellets with a diameter of 20 mm.
A cylindrical resin magnet with a thickness of 7 mm and a thickness of 7 mm was obtained. The obtained magnet has a maximum energy product (rllll) max =
2.12 MG-Oe) was excellent.

Example 3 In place of the stron powder with an average particle size of 1 (l lt m), sl- powder with an average particle size of 200 μm obtained by crushing and annealing in the same manner as the coarse powder was used. Example 1 using rhodium ferrite coarse powder
In exactly the same manner as (7゛c), the resin magnet material of the present invention was obtained, and then pelletized and injection molded in the same manner to produce a cylindrical anisotropic (1↓JI) l magnet with a diameter of 201 mm and a thickness of 7 mm. The obtained magnet has the maximum energy f* (old 1) ma
The result was an excellent value of -2,00 MG-Oe.

Example 4 Average 161'A 1.2 as ferrite powder
37 parts of ram ferrite fine powder and 55.5 parts of strong ferrite adhesion powder having an average particle size of 200 μm similar to that used in Example 3 were added.
A tree III magnet material of the present invention was obtained in exactly the same manner as in Example 1 except that 7.5 parts of 6-nylon was used as the synthetic resin, and then it was similarly rounded and injection molded to obtain a diameter. A cylindrical anisotropic resin magnet with a diameter of 20+n, j¥sa7peng was obtained.

The obtained magnet has a maximum energy product (Bll) max
= 2.07 MG・Oe, which was excellent.

Example 5 38.2 parts of strontj and rum ferrite fine powder with an average particle size of 1.2 μn1 and 57.3 parts of strontip and rum ferrite coarse powder with an average particle size of 200 μm similar to those used in Example 3 were placed in a Henschel mixer. After mixing at 110
Paraffin wax using two rolls heated to 5°C
．． The mixture was kneaded with 5 parts and made into a beveled and throated resin magnet material having a grain size of 311 m.

This was injection molded in a magnetic field of 120,000e (molding temperature 1
40° C.) to obtain a cylindrical anisotropic resin magnet with a diameter of 20 m++ and an I height of 7 mm. The obtained magnet had an extremely excellent maximum energy ME (Till) max =2.24 MG·Oe.

Example 6 Anisotropic sintered barium ferrite magnet [residual flux density Br=4 (100G, coercive force BLLC-240
00e, intrinsic coercive force 111c = 25000e, maximum energy product (BH) tnax = 3.8 MG
The resin magnet material of the present invention was obtained in exactly the same manner as in Example 1, except that barium ferrite coarse powder with an average particle size of 100 μm obtained by crushing and annealing Oe) was used in the same manner as in Example 1, and then in the same manner as in Example 1. Pelletized and injection molded into 'diameter'
A cylindrical anisotropic resin magnet with a thickness of 7 mm was obtained. The obtained magnet had the maximum energy product (formerly 1) max =
It was an excellent L87MG Oe.

Comparative Example 1 In Example 1, a resin magnet material was prepared in exactly the same manner as in Example 1, except that 88 parts of strontico-wool ferrite fine powder with an average particle size of 1.2 μm was used as the ferrite powder, and 12 parts of nylon 6 was used as the synthetic resin. obtained, then similarly pelletized,
Injection molded cylindrical chamber with a diameter of 20 tuna and a thickness of 7 m11,
Orientation 4 also obtained (ntt vit stone).

The obtained magnet has a squareness ratio Br/4πTs=0.96,
'3) It was a highly oriented magnet, but the filling rate was low,
Maximum energy product (lii) max=1.63MG・O
The magnetic properties were inferior to e.

Comparative Example 2 As ferrite powder, 46.3 parts of strontium ferrite fine powder with an average particle size of 1.2 μm and 46.3 parts of fine strontium ferrite powder were used in the same manner as in Example 1. 1. 46.3 parts of 111 powder with an average particle diameter of 500 μm obtained by crushing and annealing a sintered strondium ferrite magnet was used, and 7.4 parts of C6-nylon was used as a synthetic resin. Except for this, a 11N magnet material was obtained in exactly the same manner as in Example 1, and then subjected to pelletizing and injection molding to obtain a cylindrical W-tropic resin α1 stone with a diameter of 201 mm and a thickness of 7 mm. The obtained magnet has a squareness ratio Br/4πIs=(1,918) and has a slightly low orientation, with a maximum energy ML (BID max
・=1.83 NG・Oe, which was poor in magnetic properties.

Comparative Example 3 Ferrite powder and L2: 37.2 parts of strondium ferrite fine powder with an average particle size of 1.2 μm and tt: Comparative Example 2
Using 55.8 parts of strontium ferrite coarse powder with an average particle size of 500 pm similar to that used in 1), a cylindrical anisotropic resin containing 7 parts of 6-S.Iron was used as the synthetic resin.
I got a magnet. The obtained magnet has a squareness ratio Br/4πl5-0
．． 902, a low orientation magnet, and the maximum energy f
ff (Bit) max = 1.86 MG・Oe
It had inferior magnetic properties.

Square shape showing the magnetic properties (residual flux density, coercive force, intrinsic coercive force, maximum energy) and degree of orientation of the anisotropic resin magnets obtained in Examples 1 to 6 and Comparative Examples 1 to 3 The ratio values are shown in Table 1.

Also, Example 2, Example 4 and Ratio I! 12 The resin magnet obtained in Example 3 was removed and cut to an outer diameter of 20+u,
It was made into a ring shape with an inner diameter of 10 mm and a thickness of 2111 mm, and this was made into a Y-square 1 (1 was magnetized with 16 poles to obtain a multi-polar magnetized magnet, and the surface magnetic flux density was measured with a Gauss meter. Table 2 shows the variations in magnetic flux density (magnetic variations).

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Claims (1)

[Claims] W uniform grain '4 yen (1.5 to 1.5 μm ferrite fine powder and average particle size 30 to 250 it m ferrite powder 1
:(Soelai 1 blended with a weight/p ratio of 1,4 to 124)
- A resin magnet material comprising a mixture of 88-96% by weight of powder and 12-4% by weight of synthetic resin.