JP3361502B2 - Magnetic material, molded product thereof, high-density ferrite electronic component obtained by using the same, and methods for producing them - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel magnetic material consisting of a ferrite granule having at least a part of its surface coated with a specific fatty acid ester, a method for producing this magnetic material, a molded body of this magnetic material, The present invention relates to a high-density ferrite electronic component obtained by using this and a manufacturing method thereof.

[0002]

2. Description of the Related Art Ferrite generally has excellent heat resistance, chemical resistance, mechanical properties and the like, and has a large electric insulation property. It is widely used as a material for manufacturing various electronic components.

As a method for manufacturing such a ferrite electronic component, various methods have been conventionally adopted, but among them, the dry pressure molding method is generally widely used. This is, for example, an aqueous slurry prepared from ferrite powder, a binder and water and spray-dried with a spray dryer, or a granulated product obtained by stirring or mixing the ferrite powder and a binder solution, followed by drying and oscillating. This is a method of press-molding a granulated body obtained by repeating extrusion granulation, and by sintering the molded body thus obtained, a ferrite electronic component is obtained.

In such a pressure molding method, it is necessary to use, as the ferrite granulated material, one having good fluidity, filling in a mold and easily crushed by a small pressure. It is important from the standpoint of improving quality and increasing productivity. By the way, as a method for producing a granule having good fluidity and being easily crushed by a small pressure, a method of preparing a slurry using a dispersant and granulating the slurry has been hitherto disclosed (Japanese Patent Laid-Open No. 5-159918). Japanese Patent Publication No. 7-17460), a method of granulating while suppressing segregation of the binder (Japanese Patent Publication No. 3-31660, Japanese Patent Laid-Open No. 10-59776) and the like are known.

However, these methods are techniques generally applied to the spray-drying granulation method using a spray dryer, and even when applied to the oscillating extrusion granulation method, a predetermined effect can be exhibited. Can not. Moreover,
This method improves the fluidity of the granules and the ease of crushing under a small pressure, but the density variation of the obtained molded article for electronic component production, the releasability from the mold, the inside of the molded article due to springback No satisfactory effect has been obtained with regard to cracks and longer life of the mold.

In order to overcome such drawbacks, the present inventor previously proposed a material for producing high density ferrite electronic parts, in which at least a part of the surface of a ferrite granule is coated with a hexitan ester of a higher fatty acid. Yes (Patent application 11
-270769). This material improves the fluidity of the granules during dry pressure molding, the ease of crushing under a small pressure, and the extraction pressure when removing from the mold is lower than that of the conventional material, resulting in spring back ( Although it has the effect of suppressing the occurrence of cracks inside the molded product due to (expansion of the molded product) to some extent, it is always satisfactory in terms of the density variation of the resulting molded product and the releasability from the mold. Not only that, but the strength of the molded body and the electronic component obtained by sintering the molded body was insufficient.

[0007]

Under these circumstances, the present invention has good mold releasability from a mold, is free from molding defects such as cracks due to springback, and is uniform and excellent in electromagnetic characteristics. And a magnetic material that provides a high-density high-density ferrite electronic component.

[0008]

Means for Solving the Problems The present inventor has crushed with a much smaller pressure as compared with the previously proposed ferrite granules having at least a part of the surface coated with a hexitane ester of a higher fatty acid, and Develop a magnetic material that has less wear and damage, is effective in achieving a longer mold life, suppresses the occurrence of cracks due to springback, and provides high-density ferrite electronic components with higher strength through sintering. As a result of diligent research for the purpose of using a hexitan ester of a higher fatty acid, a hexitan fatty acid ester polyoxyalkylene condensate having a hydrophilic lipophilicity ratio (hereinafter abbreviated as HLB) of 14 or less was used to replace at least a part of the surface It was found that the object can be achieved by using a ferrite granule coated with, and the present invention has been completed based on that finding.

That is, the present invention relates to a magnetic material for producing a high density ferrite electronic component, which comprises a ferrite granule having at least a part of its surface coated with a condensate of a hexytan fatty acid ester polyoxyalkylene having an HLB of 14 or less,
The present invention provides a molded product for producing a high-density ferrite electronic component, which is obtained by molding the same, and a high-density ferrite electronic component, which is obtained by sintering the molded product. The magnetic material is granulated by adding a binder to, for example, ferrite powder, and after adding a hexan fatty acid ester polyoxyalkylene condensate having an HLB of 14 or less to the granulated material, the two are well contacted with each other. Can be produced by adhering the hexitane fatty acid ester polyoxyalkylene condensate to at least a part of the surface of the granulated product, and the electronic component can be produced by the hexan fatty acid ester polyoxyalkylene having an HLB of 14 or less. It can be produced by molding a ferrite granulated body, at least a part of the surface of which is covered with a condensate, into a predetermined shape and then sintering the molded body.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The ferrite granules used as the main material of the magnetic material for producing high density ferrite electronic parts of the present invention are the same as those used in the manufacture of electronic parts in general. The ferrite powder can be granulated and produced by the same method, for example, a spray granulation method using a spray dryer or an oscillating extrusion granulation method. The type and particle size of the ferrite used at this time are not particularly limited, and can be appropriately selected depending on the intended use and application of the ferrite electronic component. The particle size range of this ferrite powder is usually in the range of 0.5 to 5 μm. In the present invention, this ferrite powder may be used alone or in combination of two or more kinds.

A binder is usually used for granulating the ferrite powder. As this binder,
It is possible to arbitrarily select and use from publicly known ones generally used in granulation of conventional ferrite powder. Examples of such binders include partially saponified products of polyvinyl alcohol and polyvinyl acetate, polyacrylic acid, methyl cellulose, and homopolymers and copolymers of acrylamides. These binders are usually 0.2 per 100 parts by mass of ferrite powder.
It is used in the range of 10 to 10 parts by mass, preferably 0.5 to 8 parts by mass, and more preferably 0.7 to 5 parts by mass.

When granulating the ferrite powder, if desired, within a range not impairing the object of the present invention, if desired.
Various known additives, for example, polycarboxylic acid salts, dispersants such as condensed naphthalene sulfonates, plasticizers such as glycerin, glycols, triols, waxes, lubricants such as stearic acid and its salts, and polyethers. System, urethane modified polyether system, polyacrylic acid system,
An organic polymer flocculant such as a modified acrylic acid type or an inorganic flocculant such as aluminum sulfate, aluminum chloride or aluminum nitrate may be added. The ferrite granules thus obtained may have a particle size within the same range as the ferrite granules that are generally used in the production of conventional electronic parts, and there is no particular need to change it.
This particle size range is usually an average particle size of 50 to 500 μm, preferably 70 to 300 μm.

Next, the hexitane fatty acid ester polyoxyalkylene condensate with which at least a part of the surface of the ferrite granules is coated, is a hexitol obtained by reducing various hexoses, that is, hexoses, such as sorbitol and mannitol. A hexan fatty acid ester obtained by reacting knit with a fatty acid for esterification and then undergoing intramolecular dehydration, which is obtained by condensing an alkylene oxide such as ethylene oxide or propylene oxide, and is easily available as a commercial product. You can

The above fatty acid has 12 to 18 carbon atoms.
The fatty acids of are preferred, and examples of such fatty acids include:
Examples thereof include lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, natural mixed fatty acids, and the like, with palmitic acid, stearic acid, and oleic acid being particularly preferable.

What is used in the present invention may be a partial ester or a complete ester of these fatty acids and hexitane. Further, examples of the alkylene oxide to be condensed with these hexitane fatty acid esters include ethylene oxide and propylene oxide. The alkylene oxide is usually 3 to 30, preferably 5 to 2.
Those condensed in the range of 0 are used. Commercially available products of such a hexitane fatty acid ester polyoxyalkylene condensate include, for example, sorbitan oleic acid lauric acid mixed ester polyoxyethylene condensate, sorbitan hexaoleic acid ester polyoxyethylene condensate, sorbitan mixed fatty acid ester. Polyoxyethylene condensate, sorbitan monolaurate polyoxyethylene condensate, sorbitan monopalmitate polyoxyethylene condensate, sorbitan monostearate polyoxyethylene condensate,
Examples thereof include sorbitan tristearate polyoxyethylene condensate, sorbitan monooleate polyoxyethylene condensate, and mannitane monopalmitate polyoxyethylene condensate.

The HLB of the hexitane fatty acid ester polyoxyalkylene condensate used in the present invention must be 14 or less. When it exceeds 14, the releasability of the magnetic material from the mold and the pressure moldability with a small pressure are good, but the strength of the molded body is lowered.

In the magnetic material for producing high density ferrite electronic parts of the present invention, the amount of the hexitan fatty acid ester polyoxyalkylene condensate covering the surface of the ferrite granulated product is 0 based on the mass of the ferrite granulated product. .1
It is preferably from 3.0% by mass.

If the amount of the hexitan fatty acid ester polyoxyalkylene condensate is less than 0.1% by mass based on the mass of the ferrite granulated product, the effect of the present invention is not sufficiently exhibited, and more than 3.0% by mass. However, even if the amount is increased, the effect is not improved, rather the strength of the molded body is significantly lowered, which is disadvantageous economically. Considering the effect and economical efficiency, the amount of the hexitane fatty acid ester polyoxyalkylene condensate used is in the range of 0.2 to 2.0% by mass, and particularly 0.3 to
A range of 1.5% by mass is suitable.

Next, according to the method of the present invention, in order to produce a ferrite granule having at least a part of its surface coated with a polyoxyalkylene condensate of hexitane fatty acid, the ferrite powder is granulated as described above. After that, it is necessary to bring this into contact with a hexan fatty acid ester polyoxyalkylene condensate having an HLB of 14 or less. When ferrite powder is mixed with hexitan fatty acid ester polyoxyalkylene condensate before granulation, the mold releasability from the mold at the time of mold molding is insufficiently improved, and there is no molding failure due to springback, resulting in high strength. Cannot be obtained.

To coat the ferrite granules with the hexitane fatty acid ester polyoxyalkylene condensate, for example, the hexitane fatty acid ester polyoxyalkylene condensate is added with a solvent, such as ethyl alcohol, for 1.5 times.
˜3 times diluted and added to ferrite granules and mixed using a mixing device such as a drum mixer, or while rolling the granules using a rolling fluidized bed,
It is carried out by removing the solvent after contacting with the hexitane fatty acid ester polyoxyalkylene condensate. In addition, a method of atomizing and adding a solution of a polyoxyalkylene condensate of hexitane fatty acid ester, a method of mechanically mixing in a solid state or in a molten state, and the like can be used.

Next, one example of a preferred embodiment for producing a magnetic material for producing high density ferrite electronic parts by the method of the present invention will be described. First, ferrite powder is prepared by, for example, a spray dryer method or a spray forming method. Granulated by a granulation method or an oscillating extrusion granulation method to obtain an average particle size of 80 to 3
At least a part of the surface of the ferrite granules is covered with a urbitan fatty acid ester polyoxyethylene condensate having an HLB of 14 or less at a predetermined ratio by making a granule having a size of 00 μm Let The coating at this time is preferably performed so that the entire surface of the ferrite granule is uniformly covered, but it is sufficient if a part thereof, for example, 10% or more of the surface area is covered. At this time, a part of the sorbitan fatty acid ester polyoxyethylene condensate may penetrate into the surface layer of the ferrite granule, but there is no particular problem.

In this way, the ferrite granules were mixed with H
By including the sorbitan fatty acid ester polyoxyethylene condensate having an LB of 14 or less in the above range, slipperiness, fluidity and pressure transferability in mold molding are improved, and filling into a mold becomes good. Further, since the reduction in the strength of the molded body is small, it is possible to suppress the occurrence of molding defects such as cracks and chips. As a result, it is possible to obtain a magnetic material for producing high-density ferrite electronic parts, which can give a molded product with little variation at low pressure.

Next, a ferrite granulated product obtained by coating at least a part of the surface thus obtained with a sorbitan fatty acid ester polyoxyethylene condensate having an HLB of 14 or less is molded to form a molded product for producing high density ferrite electronic parts. In order to manufacture, the ferrite granules coated as described above are molded into a desired shape by a usual molding method. In this mold forming, it is particularly advantageous to dry-mold the ferrite granules using a mold. The pressing pressure at this time is usually 40 to 500 MPa, preferably 80 to 400
It is selected in the range of MPa. Since the ferrite granules used at this time have a good releasability, there is an advantage that the drawing pressure at the time of taking out the molded product from the mold is low and the wear and damage of the mold can be suppressed. Furthermore, due to these effects, spring back (mold body expansion) at the time of taking out the molded body from the mold is reduced, and since the molded body strength can be maintained high,
The occurrence of molding defects such as cracks and chips is prevented.

If the thus obtained molded body for producing high density ferrite electronic parts is subsequently sintered, high density ferrite electronic parts can be obtained. The sintering temperature at this time varies depending on the type of ferrite, but is generally 800 to 14
It is in the range of 00 ° C, preferably 1000 to 1300 ° C.
Is the range. Other sintering conditions and a sintering method are exactly the same as those in the case of manufacturing a conventional ferrite electronic component, and it is not particularly necessary to change them.

The thus-obtained molded article for producing a ferrite electronic component is homogeneous and has a high density, and is formed of, for example, Ni-
In the case of Cu-Zn ferrite, the density is 2.7 to 3.
It can be about 7 g / cm ³ . In addition, since this electronic component has a good mold release property, the extraction pressure when removing from the mold is low, and the springback when discharging is reduced, and the occurrence of molding defects such as cracks is less likely to occur The characteristics are excellent.

[0026]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Ni-Cu-Zn ferrite powder (average particle size 1 μm)
66 parts by mass, 34 parts by mass of water, 1.0 part by mass of binder (polyvinyl alcohol), and 0.25 parts by mass of dispersant (polycarboxylic acid ammonium salt) were mixed by a wet pulverization mixer to prepare a ferrite slurry. . Next, this slurry was spray-granulated using a spray dryer to obtain spherical granules having an average particle diameter of 150 μm. Then, sorbitan trioleate polyoxyethylene condensate (H
A 50 mass% ethyl alcohol solution of LB11) was added at a ratio of 0.6 mass% with respect to the above-mentioned granulated body, and the mixture was rotatively mixed with a drum mixer to prepare a ferrite granulated body having no aggregated powder.

Next, the magnetic material for producing high-density ferrite electronic parts thus obtained is filled in a predetermined mold and subjected to dry press molding at a molding pressure of 300 MPa to obtain a homogeneous, high-density crack-free cylinder. A molded body for core production (diameter 1.5 mm, length 1.8 mm) was obtained. The drawing pressure from the mold at this time was lower than that in the case of using a conventional ferrite granulated body, and the spring back was also reduced. In the production of this molded body for producing a cylindrical core, damage to the mold was not recognized, and wear was small, so 1.2 million shots could be continuously molded. Separately, 1.5 g of the above-mentioned magnetic material for producing high-density ferrite electronic parts was filled in a mold having a diameter of 6 mm, the molding pressure was changed between 49 and 294 MPa, and dry press molding was performed to obtain a diameter of 6 mm and a length of 6 mm. A molded body for producing a cylindrical core having a size of 16 to 19 mm was manufactured. A graph showing the relationship between the molding pressure and the density of the molded body for this sample is shown in Fig. 1 (a), and a graph showing the relationship between the density of the molded body and the drawing pressure from the mold is shown in Fig. 2 (a). A graph showing the relationship between the density and the expansion coefficient (change in springback) is shown by a solid line in FIG.

Examples 2 to 4 Using the amounts of sorbitan fatty acid ester polyoxyethylene condensate and sorbitan fatty acid ester added shown in Table 1, magnetic materials for producing high density ferrite electronic parts were prepared in the same manner as in Example 1, The diameter is 6 as in the first embodiment.
A cylindrical core manufacturing body was manufactured by molding using a mm die. The relationship between the molding pressure and the molded body density, the relationship between the molded body density and the extraction pressure from the mold, and the relationship between the molded body density and the expansion coefficient were almost the same as in the case of Example 1.

Comparative Example 1 In the same manner as in Example 1, a spherical ferrite granule having an average particle diameter of 150 μm was produced. This granulated product was molded as it was using a mold having a diameter of 6 mm as in Example 1 to manufacture a molded product for manufacturing a cylindrical core. The molded product not coated with the sorbitan fatty acid ester polyoxyethylene condensate obtained in this manner had poor slipperiness and pressure transferability, and at low pressures, only a low density molded product was obtained. Also,
In this case, the extraction pressure from the mold was considerably higher than that in Example 1, and in molding at high pressure, squeaking of the mold occurred at the time of taking out the molded body, and a fault crack was observed in the molded body. A graph showing the relationship between the molding pressure and the density of the molded body examined in the same manner as in Example 1 is shown in FIG. 1 (a), and a graph showing the relationship between the density of the molded body and the drawing pressure from the mold is shown in FIG. 2 (a). ), A graph showing the relationship between the density of the molded body and the expansion coefficient (change in springback) is shown by broken lines in FIG.

Comparative Example 2 Instead of the 50% by mass ethyl alcohol solution of the sorbitan fatty acid ester polyoxyethylene condensate in Example 1, zinc stearate fine powder was added to the granulated product in an amount of 0.
1% by mass was added, and a ferrite granule was prepared in the same manner as in Example 1 except for the above, and this was molded using the same die having a diameter of 6 mm as in Example 1. By the addition of zinc stearate, mold releasability was imparted and the drawing pressure from the mold was reduced, but a compact having a low density at low pressure and a large density variation was obtained. Further, in continuous molding of a cylindrical molded body (diameter 1.5 mm, length 1.8 mm), although there is no damage to the mold, a large amount of wear causes a molded body that deviates from the specifications of dimensions and appearance in 700,000 shots. It was The relationship between the molding pressure and the density of the molded body and the relationship between the density of the molded body and the expansion coefficient (change in springback) examined in the same manner as in Example 1 were almost the same as those in Comparative Example 1. A graph showing the relationship between the density of the molded body and the drawing pressure from the mold is shown by the dotted line in FIG.

Example 5 Ni-Cu-Zn type ferrite powder (average particle size 1 μm)
17 parts by mass of an aqueous polyvinyl alcohol solution having a solid content of 6% by mass was added to 100 parts by mass, and the mixture was mixed and stirred by a stirring granulator TM mixer (manufactured by Mitsui Mining Co., Ltd.) for granulation to prepare a granulation raw material. . This granulation raw material is dried with a belt dryer and then oscillating granulator and crusher (manufactured by Nippon Seiki Co., Ltd.)
Extruded and granulated with a sifter, and sized with a shifter
Granules were obtained by 0 μm oscillating extrusion.
Then, as in Example 1, 50 parts of sorbitan trioleate polyoxyethylene condensate of HLB11 was obtained.
A mass% ethyl alcohol solution was added to the above granules in an amount of 0.
A magnetic material for producing high-density ferrite electronic parts containing no agglomerated powder was prepared by adding 6 mass% and rotating and mixing with a drum mixer.

Next, using 1.5 g of this magnetic material, as in Example 1, by changing the molding pressure to 49 to 294 MPa and performing dry pressure molding, a homogeneous, high-density, crack-free columnar shape was obtained. Molded body (diameter 6 mm, length 16-19 m
m) was obtained. At this time, the extraction pressure from the mold was lowered, and the spring back was further reduced as compared with the case where the magnetic material granulated by the spray dryer of Examples 1 to 4 was used.

A graph showing the relationship between the molding pressure and the density of the molded body in this example is shown in FIG. 1 (b), and a graph showing the relationship between the density of the molded body and the drawing pressure from the mold is shown in FIG. 2 (b). A graph showing the relationship between the density of the molded body and the expansion coefficient (change in springback) is shown by a solid line in FIG.

Comparative Example 3 In the same manner as in Example 5, a granule having an average particle size of 250 μm was prepared. A molded body was produced in the same manner as in Example 5 except that this granulated body was directly molded and used.
In this way, when using the granules that are not subjected to the coating treatment with the sorbitan trioleate polyoxyethylene condensate, the slipperiness and pressure transferability are poor, and the compact density at low pressure is low, and A molded product with a large variation in density was obtained. In addition, the mold was squeaked when the molded product was taken out when the molding was taken out at a high pressure because of the high extraction pressure from the mold, and a crack was observed in the resulting molded product. A graph showing the relationship between the molding pressure and the density of the molded body is shown in Fig. 1 (b), and a graph showing the relationship between the density of the molded body and the drawing pressure from the mold is shown in Fig. 2 (b).
A graph showing the relationship between the density of the molded body and the expansion coefficient (change in springback) is shown by broken lines in FIG. 3 (b).

Comparative Example 4 Zinc stearate fine powder was used in place of the 50 mass% ethyl alcohol solution of the sorbitan trioleate polyoxyethylene condensate in Example 5 in a proportion of 0.1 mass% with respect to the granules. A magnetic material for producing a high-density ferrite electronic component was prepared in the same manner as in Example 5 except that the compound was added in step 5, and then this was molded into a molded body. By the addition of zinc stearate, mold releasability was imparted and the drawing pressure from the mold was reduced, but the density of the compact at low pressure was low, and the density of the compact was large. The relationship between the molding pressure and the density of the molded body was almost the same as in Comparative Example 3. Further, FIG. 2B is a graph showing the relationship between the compact density and the drawing pressure from the mold, and FIG. 3 is a graph showing the relationship between the compact density and the expansion rate (change in springback).
Each is indicated by a dotted line in (b).

Comparative Examples 5 and 6 A magnetic material for producing high density ferrite electronic parts was prepared in the same manner as in Example 1 except that the sorbitan fatty acid ester polyoxyethylene condensate shown in Table 1 and the addition amount were used.
It was molded in the same manner as in Example 1 to produce a molded body for producing a cylindrical core. The relationship between these molding pressures and the density of the molded body,
The relationship between the molded body density and the drawing pressure from the mold, and the relationship between the molded body density and the expansion coefficient were almost the same as in the case of Example 1.

Example 6 The magnetic materials for producing high density ferrite electronic parts obtained in Examples 1 and 2 and Comparative Examples 5 and 6 were 49 to 147, respectively.
Press-formed with a pressure of MPa, length 55 mm, width 12 m
A rectangular parallelepiped block molded body having m and a height of 3 mm was manufactured. The bending strength of this block molded body was measured by JIS R16 using a load tester (manufactured by Aiko Engineering Co., Ltd.).
It measured according to 01. A graph showing the relationship between the density of the molded body and the bending strength is shown in FIG. In the ferrite magnetic material compacts obtained in Examples 1 and 2 having HLB of 14 or less, the bending strength is not reduced by the coating and high strength can be maintained, but the ferrite magnetic materials obtained in Comparative Examples 5 and 6 having HLB of 15 or more are obtained. The molded article was low in flexural strength and was likely to crack. Table 1 collectively shows the granulation method, coating components, and the amount of addition (mass% as a 50% solution to the ferrite granules) of the ferrite granules of Examples 1 to 5 and Comparative Examples 1 to 6 described above.

[0039]

[Table 1]

Example 7 The magnetic materials for producing high-density ferrite electronic parts obtained in Examples 1 to 4 were press-molded at a pressure of 98 MPa, and a ring-shaped molded body having an outer diameter of 21 mm, an inner diameter of 12 mm and a thickness of 7 mm. Was manufactured. Then, these are 1030 ℃, 1
A ring-shaped core was manufactured by sintering at a temperature of 060 ° C and 1090 ° C for 2 hours. Next, the densities of these ring-shaped cores were measured by a method according to the Archimedes method. Also,
The initial permeability at 100 kHz of these ring-shaped cores was measured by LCR meter 4274A (Hewlett
It was measured by Packard, trade name). A graph showing the relationship between the sintering temperature and the density of the electronic component thus obtained and a graph showing the relationship between the sintering temperature and the initial magnetic permeability are shown as solid line graphs A to C in FIGS. 5 and 6, respectively. In the figure, A is the result of using the ferrite granule compact of Example 1, B is Example 2, and C is Example 3. In addition, Example 4
The graph showing the relationship between the sintering temperature and the density of the sintered body of the electronic component using the molded body of was almost the same as the graph A of Example 1. The graph showing the relationship between the sintering temperature and the initial magnetic permeability of the electronic components using the molded bodies of Examples 2 to 4 was almost the same as the graph A of Example 1.

Comparative Example 7 Using the molded ferrite granules obtained in Comparative Examples 1 and 2, the density and the initial magnetic permeability were measured in the same manner as in Example 7.
The relationship between the sintering temperature and the density and the relationship between the sintering temperature and the initial magnetic permeability of the thus obtained electronic component are shown as broken line graphs G and H in FIGS. 5 and 6, respectively.

Example 8 The magnetic materials for producing high-density ferrite electronic parts obtained in Examples 1 to 4 were press-molded at a pressure of 98 MPa to form a rectangular parallelepiped block having a length of 55 mm, a width of 12 mm and a height of 5 mm. Got the body This block molded body is
The block core was manufactured by sintering at a temperature of 0 ° C., 1060 ° C. or 1090 ° C. for 2 hours. The electronic components thus obtained were measured using a load tester. The relationship between the sintering temperature and the bending strength of these materials is shown as solid line graphs A to D in FIG.

Comparative Example 8 Using the ferrite granules obtained in Comparative Examples 1 and 2, molding and sintering were performed in the same manner as in Example 8 to produce a block core. The bending strength of the block core thus obtained was measured in the same manner as in Example 8. The relationship between the sintering temperature and the bending strength of these materials is shown as broken line graphs G and H in FIG.

Comparative Example 9 High-density ferrite was prepared in the same manner as in Example 5 except that the same amount of a 50% by mass ethyl alcohol solution of a sorbitan fatty acid ester polyoxyethylene condensate was added to ferrite powder from the beginning for granulation. A magnetic material for manufacturing electronic parts was prepared. A molded body was manufactured in the same manner as in Examples 7 and 8 using the magnetic material for producing a high-density ferrite electronic component and the material obtained in Example 5, respectively, and at 1030 ° C.
Was baked for 2 hours. Table 2 shows the results of measuring the density and bending temperature of the electronic components thus obtained in the same manner as in Examples 7 and 8.

[0045]

[Table 2]

As can be seen from this table, when the sorbitan fatty acid ester polyoxyethylene condensate is added to the ferrite powder in advance and granulated, and when added after granulation, the latter clearly shows better physical properties.

[0047]

EFFECTS OF THE INVENTION According to the present invention, during dry pressure molding, a slipperiness, fluidity, pressure transferability, and mold filling property are excellent, and there is little variation even at a low pressure, and a homogeneous molding is obtained. A high density ferrite magnetic material for producing electronic parts can be obtained. Further, when this magnetic material is used, the releasability is improved, and the extraction pressure at the time of taking out from the mold is reduced. As a result, wear and damage of the mold are reduced, and at the same time, it is taken out from the mold. This brings about the effects that the springback accompanying the decrease is reduced, molding defects such as cracks do not occur, and the reduction in the strength of the molded body can be suppressed.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the molding pressure and the density of the molded bodies obtained in Examples 1 and 5 and Comparative Examples 1 and 3.

FIG. 2 is a graph showing the relationship between the compact density of the compacts obtained in Examples 1 and 5 and Comparative Examples 1 to 4 and the extraction pressure from the mold.

FIG. 3 is a graph showing the relationship between the density and the expansion coefficient of the molded bodies obtained in Examples 1 and 5 and Comparative Examples 1, 3 and 4.

FIG. 4 is a graph showing the relationship between the molded body density and the molded body bending strength of the molded body obtained in Example 6.

FIG. 5 is a graph showing the relationship between the sintering temperature and the density of the electronic components obtained in Example 7 and Comparative Example 7.

FIG. 6 is a graph showing the relationship between the sintering temperature and the initial magnetic permeability of the electronic components obtained in Example 7 and Comparative Example 7.

FIG. 7 is a graph showing the relationship between the sintering temperature and the bending strength of the electronic components obtained in Example 8 and Comparative Example 8.

Claims (6)

(57) [Claims] 1. A magnetic material for producing a high-density ferrite electronic component, which comprises a ferrite granule having at least a part of its surface coated with a hexitane fatty acid ester polyoxyalkylene condensate having a hydrophilic lipophilicity ratio (HLB) of 14 or less. 2. The magnetic material for producing a high-density ferrite electronic component according to claim 1, wherein the amount of the hexytan fatty acid ester polyoxyalkylene condensate is in the range of 0.1 to 3.0% by mass based on the mass of the ferrite granulated product. material. 3. A ferrite powder to which a binder is added and granulated, and the resulting granules have a hydrophilic lipophilicity ratio (HL).
B) After adding 14 or less hexitane fatty acid ester polyoxyalkylene condensate, contact them well and attach the hexitane fatty acid ester polyoxyalkylene condensate to at least a part of the surface of the granule. A method for producing a magnetic material for producing high-density ferrite electronic parts, which is characterized. 4. Production of high-density ferrite electronic parts obtained by molding a ferrite granule having at least a part of its surface coated with a hexitane fatty acid ester polyoxyalkylene condensate having a hydrophilic lipophilicity ratio (HLB) of 14 or less. Molded body for. 5. A high density obtained by sintering a die-molded body of a ferrite granule, at least a part of the surface of which is coated with a hexitane fatty acid ester polyoxyalkylene condensate having a hydrophilic-lipophilic ratio (HLB) of 14 or less. Ferrite electronic components. 6. A ferrite granule having at least a part of its surface coated with a hexitane fatty acid ester polyoxyalkylene condensate having a hydrophilic lipophilicity ratio (HLB) of 14 or less is molded into a predetermined shape and then sintered. A method for manufacturing a high-density ferrite electronic component, comprising: