JPS5841647B2 - Manufacturing method of hexagonal plate-shaped magnetoplumbite type ferrite particle powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a magnetoblanbite type Ba having a hexagonal plate shape as a material for an anisotropic ferrite magnet.

Sr or Pb ferrite particle powder (MO+ n Fe
203 +n=5-6 However, M is Ba, Sr or Pb
), sintered magnets and rubber,
The purpose of this invention is to easily and economically produce ferrite particles suitable for use as plastic magnets.

At present, the magnetic particle powder of anisotropic ferrite magnet material, which is generally mass-produced on an industrial scale and is widely used in the largest quantity, has an irregular particle shape, and the particles and particles are not sintered. It is a Ba, Sr or Pb ferrite particle powder that causes crystallization and has distortion in the sintered crystal.

The present invention uses this particle powder to produce hexagonal plate-like particles with an excellent plate-like ratio, and has a single magnetic domain structure with an average major axis of the C-axis plane of the crystal of several μm, especially about 1 μm, The particles are individually separated, have perfect crystallinity, and have no internal strain.Also, the orientation performance of ferrite particles during press molding in the manufacturing process I of anisotropic sintered ferrite magnets, or the manufacturing of rubber and plastic magnets. The object of the present invention is to provide a new technical means that can easily produce Ba, Sr, or Pb ferrite particle powder that has excellent dispersibility in resin and orientation performance in the process.

Ba, Sr exhibiting a hexagonal plate shape obtained by the method of the present invention in the production of sintered magnets, rubber, and plastic magnets
Alternatively, when Pb ferrite particles are used, the particles have a hexagonal plate-like particle shape, and the particles are individually separated, and in addition, in the manufacturing process of anisotropic sintered ferrite magnets, Easily improve magnetic anisotropy due to excellent orientation performance of Ferrite II during press molding or excellent dispersion performance and orientation performance in resin during the manufacturing process of rubber and plastic magnets. Therefore, it has a large residual magnetic flux density Br, and at the same time, the average major axis of the C-axis plane of the crystal of the particle powder is several μm, especially 1 μm.
A high-performance anisotropic ferrite with a single magnetic domain structure of about 100%, and a high coercive force IHc due to perfect crystallinity and no internal strain, resulting in a large energy product (BHm a x 'l). It is very preferable as a magnetic powder material for magnets.

In recent years, with the miniaturization and weight reduction of electrical equipment, the magnets that are incorporated in these devices have also tended to become smaller. It is increasingly demanded.

In order to obtain a high-performance anisotropic ferrite magnet having such characteristics, the material magnetic particles for the magnet are required to have excellent powder properties and magnetic properties.

In other words, it is necessary for the powder properties to be such that the particles can easily become magnetically anisotropic due to mechanical or magnetic field orientation, and the factors that influence magnetic anisotropy include particle shape, size, etc. These include the state of aggregate particles, crystallinity, processability, etc.

The shape of Ba, Sr or Pb ferrite particles is
They are hexagonal plate-like particles with a large ratio of the average major axis of the axial plane to the thickness in the C-axis direction (plate ratio), and the particle size is such that the average major axis of the C-axis plane of the crystal is several μm, especially 1 μm. It is necessary to have a single magnetic domain structure of about 100%.

Regarding the aggregation state of Ba, Sr or Pb ferrite particles, each particle is independent one by one,
In addition, it is preferable that the cloth has a narrow particle size.

In addition, the crystallinity of Ba, Sr or Pb ferrite particles is
It is necessary to have perfect crystallinity and no internal strain.

Furthermore, in terms of workability, anisotropic sintered ferrite magnets require excellent orientation of ferrite particles during press molding in the magnet manufacturing process, while rubber and plastic magnets require excellent It is necessary that the resin has excellent dispersion performance and orientation performance in the manufacturing process.

Next, as for the magnetic properties of the Ba, Sr or Pb ferrite particles, it is required that the coercive force IHc, the residual magnetic flux density Br be as high as possible, and the degree of orientation Br/Bm be excellent.

In order to obtain a high coercive force IHc, the particles must be sized to have a single magnetic domain structure, have no crystal distortion, and have excellent orientation.

It is known that crystal grains have a high coercive force IHc when they have a single-domain structure, and barium or strontium ferrite particles have a single-domain structure when the crystal grain size is about 1 μm.

This can be seen, for example, in Japanese Patent Publication No. 49-38917.
Since the particle size is much larger than the critical particle size (approximately 1 .mu.m) for magnetically forming a single domain structure, it causes an extreme decrease in IHd7).

It is clear from the note ``.

In addition, in order to obtain a high residual magnetic flux density Br (this means that it is necessary to improve the filling properties and orientation of the particles, it is necessary to There is a demand for particle powders that have excellent orientation performance for Ferray iH particles, or excellent dispersion performance and orientation performance in resins in the manufacturing process of rubber and plastic magnets.

Next (In order to obtain excellent oriented cold Br/Bm, ζ is a hexagonal plate-like particle with an excellent plate-like ratio, each particle is independent one by one, and the crystal is perfect and there is no internal strain. and,
Particle powder is required that has excellent orientation performance of ferrite particles during press molding in the manufacturing process of anisotropic sintered ferrite magnets, or excellent dispersion performance and orientation performance in resins in the manufacturing process of rubber and plastic magnets. Ru.

Conventionally, Ba, Sr, or Pb ferrite particles, which have been mass-produced on an industrial scale and are widely used in the largest quantities, are iron oxide particles and Ba.

The mixture with Sr or Pb compound is heated to 1.1000C to 1.
It is obtained by a method of heating and firing at a high temperature of 400°C (hereinafter, this is referred to as a dry method).

). In the case of this dry method, 1.100'c~1,
Due to heating and firing at a high temperature of 400℃, at the same time as the ferrite reaction, the particles themselves grow and sinter between particles, resulting in a large mass of 100 μm or more. The material cannot be used as magnetic particle powder, and must be strongly pulverized after heating and firing.

The heated and fired product causes sintering between particles and between particles,
Since the Ba, Sr, or Pb ferrite particles are solidly coagulated, they must first be coarsened using a roll crusher or the like in order to make the average length of the C-axis plane of the crystals into a single-domain structure to about 1 μm, as described above. After pulverization, several stages of strong pulverization, such as medium pulverization and fine pulverization, must be performed using an atomizer, a vibrating mill, an attritor, or the like.

Because of the several stages of powerful pulverization, the obtained BatSr or Pb ferrite particles have an amorphous particle shape and have impact strain in the crystal particles.

Moreover, it is impossible to rub the heated and fired product, which has become a large lump due to sintering between particles and particles, by mechanical crushing into individual particles.

As mentioned above, Ba obtained by a dry method.

Sr or Pb ferrite particles have irregular particle shapes, sintering occurs between particles, and impact strain due to strong crushing. There were limitations to obtaining high-performance anisotropic ferrite magnets using particle powder.

The above-mentioned matter is described in Japanese Patent Publication No. 49-38917 as follows.

"Iron oxide and barium carbonate are mixed for a long time in a ball mill etc. to a predetermined mixing ratio of 1.100 to 1.200.
The method used is to pulverize it after firing it at ℃.
``In order to completely react iron oxide and barium salt, 1,1
Since the firing is carried out at a high temperature of 00° C. or higher, sintering between particles is significant and the average particle diameter becomes very large, about 100 μm.

``Because the particle size is much larger than the critical particle size (approximately 1 μm) that magnetically assumes a single domain structure, it leads to an extreme decrease in HdD.

Therefore, after firing, a process of pulverization is generally adopted, but the refinement of particles or crystals by pulverization leads to incompleteness of the crystals, which again greatly reduces IHc.

In addition, the following description can be found in Japanese Patent Publication No. 11704/1970.

"Mix BaCO3 and a-Fe203, and mix this with about 1.
Primary firing is performed at a temperature of 200°C or higher, usually 1,280 to 1,300°C, and then mechanically pulverized to form a powder, which is then molded in a magnetic field to easily magnetize the Bajoum ferrite particles. A method is adopted in which the directions are arranged in parallel and then secondary sintering is performed.

However, in such a particle arrangement method, as is well known, the manner and degree of arrangement are significantly affected by the particle size, particle morphology, particle size distribution, etc. of the barium ferrite particles, and particle control is limited to primary firing conditions, pulverization method, and pulverization. There are limits to what can be done due to time etc.

Therefore, in order to obtain barium ferrite with higher performance, a new manufacturing method for particle generation is required.

” As mentioned above, improving the performance of magnets lies in how to improve the magnetic anisotropy of the material magnetic particle powder.In recent years, with the trend of improving the performance of magnets, it has become difficult to improve the magnetic anisotropy of the magnetic particles. There is an increasing demand for anisotropic ferrite magnet material magnetic particle powder with excellent processing characteristics, that is, excellent orientation.

Conventionally, methods for producing Ba, Sr, or Pb ferrite particles, which have a plate-like particle shape and each particle is disjointed, have been proposed as magnetic particles having such characteristics. JP 47-25796, JP 47-5819, JP 47-49
No. 29, JP-A No. 47-4930, JP-A No. 49-Sho.
-63997 publication, JP-A-50-32498 publication,
JP-A-50-121200, JP-A-50-135
There are methods described in Japanese Patent Publication No. 000, Japanese Patent Application Laid-Open No. 53-131499, and Australian Patent No. 284335.

In the method described in Japanese Patent Publication No. 47-25796, a barium hydroxide aqueous solution containing needle-shaped a-FeO-OH crystal particles (p)(>11) is heated at 260°C using an autoclave.
It is heated at ~300°C.

In this method, since the reaction is performed under high pressure, expensive equipment such as an autoclave and special operating techniques are required.

JP-A-47-5819, JP-A-47-4929, JP-A-47-4930, JP-A-49-63
997, JP 50-32498, JP 50-121200, JP 50-135000
The methods described in Japanese Patent Application Publication No. 53-131499 and Australian Patent No. 284335 all involve heating and calcining a mixture of iron oxide particles and Ba, Sr or Pb compounds in the presence of a flux. be.

In view of the above-mentioned prior art, the present inventor has discovered that particles having an amorphous shape obtained by a dry method, which is currently mass-produced on an industrial scale and widely used in large quantities, In addition, Ba, Sr, or Pb ferrite particles are preferably used as magnetic particles for high-performance anisotropic ferrite magnets by using Ba, Sr, or Pb ferrite particles that cause sintering between the particles and between the particles and have strain in the crystal grains. Powder properties (particle shape, size, condition of aggregated particles, crystallinity, and processability) and excellent magnetic properties (coercive force IHc, residual magnetic flux density Br, and degree of orientation B)
As a result of various studies aimed at producing Ba, Sr, or Pb ferrite particle powder having the following characteristics:

That is, the present invention uses amorphous Ba as a starting material.

For Sty or Pb ferrite particles, Ba or Sr
5 to 5 or more fluxing agents selected from chloride or fluoride of Pb or bromide, iodide or oxide of Pb.
After mixing 90 wt%, magnetobrambite-type Ba exhibiting a hexagonal plate shape is obtained by heating and firing at a temperature higher than the melting point of the flux to form hexagonal plate-shaped particles in the particle shape of the starting raw material. The present invention relates to a method for producing Sr or Pb ferrite particles.

The structure and effects of the present invention will be explained as follows.

First, we will discuss the various findings on which the present invention is based.

The present inventor has determined that the anisotropic ferrite magnet material magnetic particle powder having preferable powder characteristics and excellent magnetic properties is hexagonal plate-like particles with an excellent plate-like ratio, and the average major axis of the C-axis plane of the crystal. has a single domain structure size of several μm, especially about 1 μm, the particles are individually separated, the crystallinity is perfect, there is no internal strain, and it is suitable for the manufacturing process of anisotropic sintered ferrite magnets. It was found that the ferrite particle orientation performance during press molding, and the dispersion performance and orientation performance in resin during the manufacturing process of rubber and plastic magnets are excellent.

Therefore, the present inventors have developed Ba consisting of amorphous particles obtained by the dry process, which is currently mass-produced on an industrial scale and is widely used in large quantities.

As a result of various studies using Sr or Pb ferrite particles to adjust the particle shape, particle size, state of aggregated particles, and crystallinity of the particles to the desired ones, we found that the starting material, an amorphous 5 to 90 wt% of one or more fluxes selected from Ba or Sr chloride or fluoride or Pb bromide, iodide or oxide to Ba, Sr or Pb ferrite particles. When the mixture is heated and fired at a temperature higher than the melting point of the flux, it becomes hexagonal plate-like particles with an excellent plate-like ratio, and the average major axis of the crystal C-axis is several μm, especially about 1 μm. It has the size of a single magnetic domain structure, the particles are individually separated, and the crystallinity is perfect and there is no internal strain.The orientation performance of ferrite particles during press molding in the manufacturing process of anisotropic sintered ferrite magnets. Or rubber,
They have discovered a new phenomenon in which it is possible to obtain Ba, Sr, or Pb ferrite particle powder that has excellent dispersion performance and orientation performance in resin in the manufacturing process of plastic magnets.

The above phenomenon will be explained in detail below.

In the case of the present invention, Ba, Sr, or Pb which has an amorphous particle shape obtained by the dry process, and which has caused sintering between the particles and between the particles and has strain in the crystal. Ferrite particle powder is Ba2+, Sr2+, Pb2
When heated in a melt containing + ions, the ferrite particles undergo transitions such as diffusion of internal particles, polymorphic changes in crystals, and eutectic changes, and removal of internal stress in the particles, resulting in an amorphous shape. The Ba, Sr or Pb ferrite particles consisting of particles are individually separated and exhibit a hexagonal plate shape with perfect crystallinity and an excellent plate-like ratio with no internal distortion.
It is thought that it becomes a, Sr or Pb ferrite particle powder.

Ba, Sr, or Pb ferrite particles obtained by the dry method of the present invention and consisting of irregularly shaped particles that cause sintering between particles and become large agglomerates are -
The phenomenon in which individual particles are separated into hexagonal plate-like particles with perfect crystallinity, no internal strain, and an excellent plate-like ratio is an entirely unthinkable phenomenon, and the present inventor discovered this for the first time. This is a phenomenon.

Next, specific conditions for carrying out the method of the present invention will be described.

The starting material used in the present invention is amorphous Ba obtained by a dry process, which is currently mass-produced on an industrial scale and is widely used in large quantities.

Sr or Pb ferrite particles are used, and the ferrite composition is MO-nFe203 (where M is Ba, Sr
or pb) is generally used from the viewpoint of magnetic properties (this n = 5 to 6
is within the range of

This is explained on page 42 of the Journal of the Chemical Society of Japan, No. 1 (1978), stating that ``The stoichiometric composition of barium ferrite is Ba
O-nFe2O3゜n = 6, but the magnetic properties are n
= obtained in the range of 5 to 6.

” is stated. The average particle size of the Ba, Sr or Pb ferrite particles as starting material is the same as the desired product Ba.

It may be selected by considering the size of the Sr or Pb ferrite particles.

In order to obtain product Ba, Sr or Pb ferrite particles having a single magnetic domain structure of about 1 μm, the starting material particles may be selected within the range of about 0.5 to 5 μm in average particle diameter by Blaine method.

As the flux in the present invention, one or more selected from chlorides or fluorides of Ba or Sr, or bromides, iodides, or oxides of Pb can be used, but from an industrial standpoint, BaCl2 or 5rCt2 are preferred.

The amount of the flux mixed in the present invention is 5 to 90 wt based on the total weight of the mixture consisting of the amorphous Ba, Sr or Pb ferrite particles as the starting material and the flux.

If it is less than 5 wt%, the desired effect of the present invention cannot be fully achieved, and even if it is more than 90 wt%, the object of the present invention can be achieved, but the material and equipment structure of the industrial material Considering economy rather than surface, 90wt
% or less is sufficient.

The plate ratio of the product Ba, Sr or Pb ferrite particles exhibiting a hexagonal plate shape tends to increase as the amount of flux increases, and when the plate ratio is considered, it is 10 to 70.
wt% is preferred.

The firing temperature in the present invention is preferably higher than the melting point of the flux, and the upper limit is preferably 1400°C or lower.

If it is below the melting point of the flux, the object of the present invention cannot be fully achieved.

If the temperature is 1400° C. or higher, the Ba, Sr or Pb ferrite particles grow rapidly, making it difficult to adjust the shape and size of the particles, and also being unfavorable in terms of equipment and environment.

Although the heat-fired product obtained by the present invention is in the form of lumps, if it is washed with water or an acid aqueous solution by a conventional method, the particles will be removed.
Hexagonal plate-shaped Ba, Sr with excellent plate-like ratio that each piece is separate.
Or it becomes Pb ferrite particle powder.

The present invention configured as described above has the following effects.

That is, according to the present invention, the particles are hexagonal plate-like particles with an excellent plate-like ratio, and have a single magnetic domain structure with an average major axis of the C-axis plane of the crystal of several μm, particularly about 1 μm. Ba, Sr, or Pb ferrite particles are individually disjointed, have perfect crystallinity, and have no internal molds, so they can be used to produce sintered magnets, rubber, and plastic magnets due to their excellent orientation and magnetic anisotropy. Br
Since it has a high coercive force IHC and an orientation degree Br/Bm, a high performance anisotropic ferrite magnet can be obtained.

In addition, in recent years, with the advancement of recording density in the field of magnetic recording, the perpendicular magnetization method (a method in which recording is performed by magnetizing perpendicular to the magnetic film surface), which allows for approximately three times higher density recording than conventional methods.
has been devised and put into practical use, but the hexagonal plate-shaped Ba, Sr or Pb ferrite particles with an excellent plate-like ratio obtained by the present invention cannot be used as the material magnetic particles of the perpendicular magnetization method. is also expected.

The present invention will be explained by the following example.

Incidentally, the particle shape and particle size of the examples were observed and measured using a scanning electron microscope.

Furthermore, the particle size of the starting materials was measured by the Blaine method.

<Production of starting material Ba or Sr ferrite particle powder> Starting materials 1 to 2; Starting materials l 1.26 kg of barium carbonate and 5.75 kg of ferric oxide were mixed in a wet ball mill for 5 hours, followed by filtration, molding,
After drying, the molded product was fired at 1210'C for 3 hours.

The fired product was crushed with a roll crusher and then finely crushed with a pibration mill to obtain Ba ferrite particle powder.

The obtained Ba ferrite particle powder has an irregular particle shape as is clear from the scanning electron micrograph (X 27,000) shown in FIG. It was 1.43 μm.

Moreover, the magnetic properties were measured by the following method.

The above Ba ferrite particle powder 201 and 2 ml of PVA 6.5% aqueous solution are mixed well and compressed at a pressure of 1000 kg/ffl using a mold with a diameter of 25 mm to form a powder compact with a diameter of 25 mm and a thickness of 15 mm. I got it.

This powder compact was measured at Oe in a measuring magnetic field of 10 using a DC BH tracer (manufactured by Yokogawa Electric Corporation, address Type 3257). As a result, the residual magnetic flux density Br was 1480 G.
auss, coercive force IHJ (16000e).

Starting materials 2 Strontium carbonate 1.0 kg and ferric oxide 6.0 kg
After mixing in a wet ball mill for 5 hours, filtering, molding and drying, this molded product was fired at 1200° C. for 3 hours.

The fired product was roughly crushed using a roll crusher and then finely crushed using a vibration mill to obtain Sr ferrite particle powder.

As a result of observation using a scanning electron microscope, the obtained Sr ferrite particles were found to be amorphous particles, and the average particle diameter was 1.38 μm as determined by the Blaine method.

In addition, the magnetic properties were measured using the same method as in the case of starting material 1, and as a result, the residual magnetic flux density Br was 1490 Gau
s s.

The coercive force was IH (branch) i18200e.

<Production method of hexagonal plate-shaped Ba or Sr ferrite particle powder>
Examples 1 to 12; Example 1 500v of Ba ferrite particle powder consisting of amorphous particles of starting material 1 and BaC/:22000f (80wt% based on the total weight) were mixed and placed in an alumina rutsugi,
It was heated and baked at 900° C. for 2.0 hours using an electric furnace.

Next, the heated and calcined product was washed with 10 tons of water in a conventional manner to remove BaCl2, and then filtered and dried to remove BaCl2.
Ferrite particle powder was obtained.

As is clear from the scanning electron micrograph (X52,000) shown in FIG. 2, the obtained Ba ferrite particle powder has an average major diameter of 1.1 μm on the C-axis plane and a thickness of 0.15 μm in the C-axis direction of each crystal. The particles were hexagonal plate-like particles with a plate-like ratio of 7/1), and the particles were individually separated.

In addition, the magnetic properties were measured using a method similar to that used for starting material 1, and as a result, the residual magnetic flux density Br was 152 Q G
auss, coercive force IHcIJi 30100e.

Examples 2 to 12 Ferrite particle powders were obtained in exactly the same manner as in Example 1, except that the type of starting material, the type, amount and proportion of the flux, firing temperature and firing time were varied.

As a result of scanning electron microscope observation, the ferrite particles obtained in Examples 2 to 12 were all hexagonal plate-shaped particles.

Further, Table 1 shows the powder properties and magnetic properties of the obtained hexagonal plate-shaped ferrite particle powder.

<Manufacture of rubber, plastic magnets, and sintered magnets> Examples 13 to 26 Comparative examples 1 to 4; Example 13 Ba ferrite particle powder 881 obtained in Example 1 and ethylene vinyl acetate copolymer resin (product name Evaflex # ,
EV-410 (manufactured by Mitsui Polychemical Co., Ltd.) 121 and 0.69% of zinc stearate were kneaded using a hot roll heated to 700C to form a uniform kneaded product, and then a sheet having a thickness of 1.0 mm was formed.

These sheets were punched and stacked using a punch with a diameter of 25 mm to create a cylindrical sample with a diameter of 25 mm and a thickness of 12 mm, and the magnetic properties were measured using a bolt-like method as in the case of starting material 1. Table 2 shows the results. Shown below.

Example 14 Material A sheet was prepared in exactly the same manner as in Example 13 except that the Sr ferrite particles obtained in Example 7 were used as the magnetic particles.

Using this sheet, a cylindrical sample was prepared in exactly the same manner as in Example 13, and the magnetic properties were measured in the same manner as in the case of starting material 1. Table 2 shows the results.

Example 15 120 pieces of Ba ferrite particle powder obtained in Example 1 and isoprene rubber (product name Cauliflex #IR-500,
Shell Chemical Co., Ltd.) 12.5f and stearic acid 0.6
1 and kneaded with a hot roll heated to 100°C to form a uniform mixture, which was then formed into a sheet with a thickness of 1.0 mm.

Using this sheet, a cylindrical sample was prepared in exactly the same manner as in Example 13, and the magnetic properties were measured using a method similar to that used for starting material 1. The results are shown in Table 2.

Example 16 Material A sheet was prepared in exactly the same manner as in Example 15, except that the Sr ferrite particles obtained in Example 7 were used as the magnetic particles.

Using this sheet, a cylindrical sample was prepared in exactly the same manner as in Example 13, and the magnetic properties were measured in the same manner as in the case of starting material 1. Table 2 shows the results.

Example 17 88 grams of Ba ferrite particle powder obtained in Example 1 and 121 grams of polyethylene (product name #J 519 manufactured by Ube Industries, Ltd.)
and 2 cc of dioctyl phthalate were kneaded with a hot roll heated to 120°C to form a homogeneous mixture.
It was made into a sheet of mm.

Using this sheet, a cylindrical sample was prepared in exactly the same manner as in Example 13, and the magnetic properties were measured in the same manner as in the case of starting material 1. Table 2 shows the results.

Example 18 Material A sheet was prepared in exactly the same manner as in Example 17, except that the Sr ferrite particles obtained in Example 7 were used as the magnetic particles.

Using this sheet, a cylindrical sample was prepared in exactly the same manner as in Example 13, and the magnetic properties were measured in the same manner as in the case of Starting Material 1. Table 2 shows the results.

Example 19 Ba ferrite particle powder 1151 obtained in Example 1 and nylon 6 (product name 11013B manufactured by Ube Industries, Ltd.) 15.
7f and kneaded in a kneader heated to 230°C to make a uniform kneaded product, and then coarsely crushed.
The mixture was put into a mφ mold and heated and compression molded at 180° C. and a pressure of 500 kg/i to obtain a cylindrical molded body with a diameter of 25 mm and a thickness of 15 mπ.

This molded body was prepared in the same manner as in the case of starting material 1.
Table 2 shows the results of measuring the magnetic properties.

Examples 20 to 24 Cylindrical molded bodies were obtained in exactly the same manner as in Example 19, except that the types of magnetic particles were varied.

The magnetic properties of this molded body were measured in the same manner as in the case of starting material 1, and the results are shown in Table 2.

Comparative Examples 1 and 2 Sheets were prepared in exactly the same manner as in Example 13, except that Starting Material 1 and Starting Material 2 were used as the magnetic particle powders, respectively.

Using this sheet, a cylindrical sample was prepared in exactly the same manner as in Example 13 (1), and the magnetic properties were measured in the same manner as in the case of starting material 1. Table 2 shows the results.

Comparative Examples 3 to 4 Material Sheets were prepared in exactly the same manner as in Example 15, except that Starting Material 1 and Starting Material 2 were used as the magnetic particle powders, respectively.

Using this sheet, a cylindrical sample was prepared in exactly the same manner as in Example 13, and the magnetic properties were measured in the same manner as in the case of Starting Material 1. Table 2 shows the results.

Manufacturing of sintered magnet> Examples 25 to 26; Example 2
5 Ba ferrite particle powder 20f obtained in Example 1 and PVA
Mix well with 2 ml of 6.5% aqueous solution and make a 25 mm diameter
A compacted powder body having a diameter of 25 mm and a thickness of 15 mm was obtained by compressing with a pressure of 1000 kg/- using a mold.

After drying this green compact, it was fired at 1200° C. for 60 minutes using an electric furnace to obtain a sintered sample.

The magnetic properties of this sintered sample were measured in the same manner as in the case of starting material 1. As a result, the energy product BHmax
1.2 M, G, Oe, residual magnetic flux density (Br) 240
0 Gauss, degree of orientation (Br78m) 0.57, and coercive force IHC35000e.

Example 26 20L of Sr ferrite particle powder obtained in Example 7? and water 5
After mixing well with 0cc to form a slurry, the diameter is 30mm.
Using a mold of φ, the pressure was 10 after orientation in a magnetic field of Oe.
Compression molded at 0kg/ffl, 1 diameter 30 threads φ, thickness 10
A cylindrical powder compact with a diameter of mm was prepared.

After drying this green compact, it was fired in an electric furnace at 1230° C. for 60 minutes to obtain a sintered sample.

The magnetic properties of this sintered sample were measured in the same manner as for starting material 1. As a result, the energy;
x3.8M, G, Oe, residual magnetic flux density (Br) 4130
The degree of Gauss1 orientation (Br78m) was 0.91 and the coercive force IHc was 31000e.

[Brief explanation of the drawing]

Figures 1 and 2 are both scanning electron micrographs, Figure 1 is the starting material of amorphous Ba ferrite particles obtained by the dry method, and Figure 2 is the powder of Ba ferrite particles obtained from Example ig. This is Ba ferrite particle powder exhibiting a hexagonal plate shape.

Claims (1)

[Scope of Claims] 1. For the amorphous Ba, Sr or Pb ferrite particles which are the starting materials, one selected from Ba or Sr chloride or fluoride or Pb bromide, iodide or oxide or The particle shape of the starting raw material is made into hexagonal plate-like particles by mixing 5 to 90 wt% of two or more types of fluxes and then heating and firing at a temperature equal to or higher than the melting point of the fluxes. A method for producing magnetoblanbite-type Ba, Sr or Pb ferrite particles having a hexagonal plate shape. 2. The method for producing magnetobrambite-type Ba ferrite particles having a hexagonal plate shape according to claim 1, wherein the flux is B a C12. 3. A method for producing magnetobrambite-type Ba ferrite particles having a hexagonal plate shape according to claim 2, in which 10 to 70 wt% of BaCl2 is mixed in the amorphous Ba ferrite particles as a starting material. . 4. A method for producing magnetobrambite-type Sr ferrite particles having a hexagonal plate shape according to claim 1, wherein the flux is 5rC12. 5. A method for producing magnetobrambite-type Sr ferrite particles having a hexagonal plate shape according to claim 4, in which 10 to 70 wt% of 5rCj2 is mixed in the amorphous Sr ferrite particles as a starting material. .