JP4893680B2 - Ferrite particle powder for bonded magnet, resin composition for bonded magnet, and molded body using them - Google Patents

Description

  The present invention provides a ferrite magnet powder for bonded magnets and a bonded magnet that can obtain a bonded magnet molded body having excellent moldability, particularly mechanical strength even when quenched during injection cooling, and excellent magnetic properties of the molded product. The present invention relates to a resin composition, and relates to a ferrite magnet powder and a bonded magnet molded body such as a magnet roll using the composition.

  As is well known, bond magnets have advantages such as light weight, good dimensional accuracy, and easy mass production of complex shapes compared to sintered magnets. For toy, office equipment, acoustic equipment, and motors. It is widely used for various applications such as.

  As magnetic powders used in bond magnets, rare earth magnet powders and ferrite particle powders typified by Nd—Fe—B are known. Although rare earth magnet powder has high magnetic properties, it is also expensive and has limited uses. On the other hand, ferrite particle powder is inferior in terms of magnetic properties as compared with rare earth magnet powder, but it is inexpensive and chemically stable, so it is used in a wide range of applications.

  Bond magnets are generally manufactured by kneading a rubber or plastics material and magnetic powder and then molding them in a magnetic field or by mechanical means.

  In recent years, with improved functionality including improved productivity of various materials and equipment and improved reliability during use, improved productivity of bonded magnets used, improved mechanical strength, improved magnetic properties There is a need for performance.

  That is, during production by injection molding of bonded magnets, in order to increase production efficiency by increasing the number of injections per unit time in addition to general characteristics, in other words, in order to increase production efficiency, rapid cooling immediately after injection It is necessary to use a material with excellent quenching resistance that does not adversely affect strength even if it is cooled rapidly, and mechanical strength that can withstand harsh usage conditions when used in each application. Is required.

  For example, although a magnet roll is used in a copying machine, a printer, and the like, it is strongly required to have a high mechanical strength because it is used for extending the life of the apparatus and rotating at high speed. In addition, in the magnetic characteristics of the magnet roll, the magnetic force uniformity on the surface of the magnet roll is particularly required as an important elemental technique for obtaining a clear image from a copying machine, a printer, etc., along with an increase in surface magnetic force.

  Accordingly, a ferrite particle powder used for a bond magnet and a resin composition for a bond magnet composed of ferrite particles and an organic binder are also required to satisfy the above requirements.

  So far, various improvements have been made to the bonded magnet ferrite particles and the bonded magnet resin composition comprising ferrite particles and an organic binder. For example, an alkali metal compound or an alkaline earth metal compound is used as a flux. A method of producing ferrite particle powder (Patent Document 1), a method of acid-treating ferrite particle powder and then surface-treating with a phosphoric acid coupling agent (Patent Document 2), and surface-treating ferrite particle powder with a phosphoric acid compound Method (Patent Document 3), Method of subjecting ferrite particle powder to alkali treatment and then surface treatment with coupling agent (Patent Document 4), Method of controlling particle size distribution of ferrite particle powder (Patent Document 5), Alkaline earth metal With an average particle size of 1.50 μm or more and a melt flow value of 91 g / 10 min or more. How to bond magnet using preparative magnetic powder (Patent Document 6) are known.

JP 55-145303 A JP-A-4-93002 JP 2007-281181 A JP-A-5-41314 JP-A-3-218606 JP 2005-268729 A

  The ferrite particle powder for bonded magnets and / or the resin composition for bonded magnets that satisfy the above-mentioned requirements are currently most demanded, but those that sufficiently satisfy the above-mentioned requirements have not yet been obtained.

  That is, the ferrite particle powder described in the above-mentioned Patent Documents 1, 2, 4 to 6 or the bonded magnet molded product using the resin composition for bonded magnets has high magnetic force, uniform magnetic force, and mechanical strength. It is hard to say that it is excellent.

Patent Document 3 discloses a technique for improving the mechanical strength of a molded article by treating the ferrite surface with a phosphoric acid compound, for example, in a bonded magnet ferrite particle powder in which phosphorus is adsorbed and / or contained. .
According to the technique described in Patent Document 3, the mechanical strength of the molded product can be improved. However, the phosphate compound disclosed therein is substantially dissociated in the solution during the surface treatment because the phosphate compound ions are dissociated in the solution. It reacts as an acid. Therefore, at 200 to 400 ° C. which is the molding temperature, voids, that is, voids are generated in the molded body due to decomposition products or water vapor generated by decomposition and / or intramolecular dehydration of those phosphate compounds, It is not considered to deteriorate the characteristics.

  The present invention uses a ferrite particle powder for bonded magnets that adsorbs and / or contains a phosphate compound that does not cause decomposition and / or intramolecular dehydration at a molding temperature of 200 to 400 ° C. It is effective in preventing the generation of voids having a size that can cause a decrease in mechanical strength, that is, voids.

  Then, this invention makes it a technical subject to obtain the ferrite particle powder for bond magnets and the resin composition for bond magnets which can obtain the bond magnet which was excellent in the high magnetic force and magnetic force uniformity, and was excellent in mechanical strength.

  The technical problem can be achieved by the present invention as follows.

That is, the present invention is a phosphoric acid compound in which the phosphoric acid compound does not undergo decomposition and / or intramolecular dehydration at 200 to 400 ° C. in a ferrite particle powder for bonded magnet containing and / or containing a phosphoric acid compound. The ferrite particle powder for bonded magnets, wherein the content of the phosphorus compound in the ferrite particle powder is 120 to 1610 mg / kg (0.012 to 0.161 wt%) as P (the present invention) 1).

The present invention also relates to a resin composition for a bonded magnet comprising an organic binder component, a ferrite particle powder for bonded magnet, and a phosphoric acid compound, wherein the content of the ferrite particle powder is 70 with respect to the resin composition for bonded magnet. The phosphoric acid compound does not undergo decomposition and / or intramolecular dehydration at 200 to 400 ° C., and the content of the phosphoric acid compound is 100 to 1440 mg / kg (0 0.010 to 0.144 % by weight) (bonded magnet resin composition) (Invention 2).

Further, the present invention is a resin composition for a bond magnet comprising an organic binder component, a ferrite particle powder for a bonded magnet, a phosphoric acid compound and a silane coupling agent, wherein the content of the ferrite particle powder is a resin composition for a bonded magnet The phosphoric acid compound is a phosphoric acid compound that does not undergo decomposition and / or intramolecular dehydration at 200 to 400 ° C., and the content of the phosphoric acid compound is 100 to 1440 as P. It is mg / kg (0.010 to 0.144 % by weight), and the silicon content is 1000 to 10,000 mg / kg (0.10 to 1.0 % by weight) as SiO ₂ . It is a resin composition (Invention 3).

  Moreover, this invention is a resin composition for bonded magnets of this invention 2 or 3 characterized by the organic binder component being a polyamide resin (Invention 4).

  Further, the present invention is a molded body characterized by using either the ferrite particle powder for bonded magnet according to the present invention 1 or the resin composition for bonded magnet according to any one of the present inventions 2 to 4. There is (Invention 5).

  Moreover, this invention is a molded object of this invention 5 characterized by a molded object being a magnet roll (this invention 6).

  The ferrite particle powder for bonded magnets according to the present invention contains 120 to 5000 mg / kg of phosphorus as P, and a part or all of them are chemically adsorbed or chemically bonded to the ferrite particles as pyrophosphate ions and metaphosphate ions. It is a magnetic powder having excellent dispersibility while maintaining good surface properties with an organic binder or / and silane coupling agent, and is suitable as a magnetic powder for bond magnets.

  The resin composition for bonded magnets according to the present invention contains a ferrite for bonded magnets, an organic binder, a silane coupling agent, phosphorus, and the like, and a molded article having excellent quenching resistance and magnetic characteristics can be obtained. It is suitable as a resin composition.

  The magnet roll according to the present invention is suitable as a magnet roll for printers, copiers and the like because of excellent mechanical strength and uniformity of surface magnetic force, high surface magnetic force, and a reduced number of voids.

  Hereinafter, the present invention will be described in detail.

  First, the ferrite particle powder for bonded magnet according to the present invention (hereinafter referred to as “ferrite particle powder”) will be described.

  The composition of the ferrite particle powder according to the present invention is not particularly limited, and may be any of Sr-based ferrite particle powder and Ba-based ferrite particle powder, a mixture thereof, and further La, Nd, Pr, You may contain dissimilar elements, such as Co and Zn. Either isotropic or anisotropic ferrite may be used, but it is preferable to use anisotropic ferrite in order to increase the magnetic force on the surface of a molded body such as a magnet roll.

  The phosphoric acid compound used in the present invention is one that does not undergo decomposition and / or intramolecular dehydration in a temperature range of at least 200 to 320 ° C, preferably 200 to 400 ° C. Specifically, phosphoric acids such as pyrophosphoric acid and metaphosphoric acid and / or phosphates thereof.

  The content of the phosphoric acid compound in the ferrite particle powder according to the present invention is 120 to 5000 mg / kg (0.012 to 0.50% by weight). When the phosphoric acid compound content is less than 120 mg / kg, the molded product obtained by molding a kneaded product with an organic binder by injection molding or the like has sufficient magnetic properties such as mechanical strength and uniformity of surface magnetic force. Not. If it exceeds 5000 mg / kg, the mechanical strength is insufficient and a good molded product cannot be obtained. Preferably it is 140-4000 mg / kg, More preferably, it is 150-3000 mg / kg.

  The average particle size of the ferrite particle powder according to the present invention is not particularly limited, but is preferably 1.0 to 3.0 μm. When the average particle size is outside the range of 1.0 to 3.0 μm, it becomes difficult to obtain a bonded magnet having high magnetic properties because high filling cannot be performed when the bonded magnet is formed. More preferably, it is 1.0-2.5 micrometers, More preferably, it is 1.0-2.0 micrometers.

The BET specific surface area value of the ferrite particle powder according to the present invention is not particularly limited, but is preferably 1.0 to 3.0 m ² / g. More preferably, it is 1.0-2.5 m < ² > / g.

The compression density CD of the ferrite particle powder according to the present invention is not particularly limited, but is preferably 3000 to 3500 kg / m ³ (3.00 to 3.50 g / cm ³ ). When the compression density is less than 3000 kg / m ³ (3.00 g / cm ³ ), since the filling property is lowered, a bonded magnet having high magnetic properties cannot be obtained. When the compression density exceeds 3500 kg / m ³ (3.50 g / cm ³ ), there is no problem in magnetic properties and the like, but industrially stable production is difficult. More preferably ^{3100kg / m 3 ~3500kg / m 3} (3.10~3.50g / cm 3). More preferably from ^{3200kg / m 3 ~3450kg / m 3} (3.20~3.45g / cm 3).

The saturation magnetization value σ _s of the ferrite particle powder according to the present invention is preferably 65.0 to 73.0 Am ^{2 /} kg (65.0 to 73.0 emu / g), and the coercive force Hc is not particularly limited. 135-279 kA / m (1700-3500 Oe).

  Next, a method for producing a ferrite particle powder according to the present invention will be described.

  The ferrite particle powder according to the present invention is a phosphorus compound (for example, phosphoric acids such as pyrophosphoric acid, metaphosphoric acid, etc.) that does not decompose and / or dehydrate in the magnetoplumbite type ferrite powder as a precursor at 200 to 400 ° C. And / or its phosphate).

  The magnetoplumbite type ferrite powder used as a precursor is a commercially available product or a raw material powder mixed and mixed at a predetermined mixing ratio, and the obtained raw material mixed powder is temporarily prepared in the air at a temperature range of 900 to 1250 ° C. After baking, either or both of those obtained by pulverizing and washing with water and then annealing and heating in the temperature range of 700 to 1100 ° C. in air may be used in combination.

  The raw material powder may be appropriately selected from oxide powders, hydroxide powders, carbonate powders, nitrate powders, sulfate powders, chloride powders and the like of various metals forming magnetoplumbite-type ferrite. In consideration of improvement in reactivity during firing, the particle size is preferably 2.0 μm or less.

In the present invention, it is preferable to add a flux to the raw material mixed powder and fire it. As the flux, various fluxes can be used, for example, SrCl ₂ · 2H ₂ O, CaCl ₂ · 2H ₂ O, MgCl ₂ , KCl, NaCl, BaCl ₂ · 2H ₂ O and Na ₂ B ₄ O _7. It is. The addition amount is preferably 0.1 to 10 parts by weight per 100 parts by weight of the raw material mixed powder. More preferably, it is 0.2-8.0 weight part.

In the present invention, Bi ₂ O ₃ may be added to and mixed with the raw material mixed powder or the pulverized powder after firing.

  In the present invention, two or more types of ferrite particle powders having different particle diameters may be used in combination from the viewpoint of particle size distribution control.

  The phosphoric acid compound in the present invention is a phosphoric acid compound such as pyrophosphoric acid or metaphosphoric acid, or a phosphate compound such as sodium pyrophosphate, sodium metaphosphate, potassium metaphosphate or sodium hexametaphosphate. It is a phosphoric acid compound that does not cause decomposition and / or intramolecular dehydration.

  What is necessary is just to add the addition amount of a phosphoric acid compound so that content of the phosphoric acid compound which exists in ferrite particle powder may be 120-5000 mg / kg (0.012-0.50 weight%). For example, in the case of pyrophosphoric acid or a salt thereof, 0.035 to 2.70 parts by weight is preferable with respect to 100 parts by weight of the ferrite particle powder. In the case of metaphosphoric acid or a salt thereof, 0.031 to 1.91 parts by weight is preferable with respect to 100 parts by weight of the ferrite particle powder.

  In addition, in the ferrite particle powder, phosphorus as an impurity mixed from raw materials, industrial water used at the time of production, or the like may exist in an amount of about 80 to 90 mg / kg as P, and 120 mg / kg including this impurity content. The above P content is important in achieving the present invention.

  The mixing method of the magnetoplumbite type ferrite particle powder as a precursor and the phosphoric acid compound may be performed by a conventional method, which may be either dry or wet. Dry mixing, which does not need to be provided, is suitable. In dry mixing, both batch processing and continuous processing are possible, and it is not particularly limited. However, batch-type dry mixing machines include high-speed mixing type high-speed mixers, Henschel mixers, and medium-to-low-speed mixing types. A nauter mixer, sand mill, etc. can be used, and if it is added with a magnetplumbite type ferrite particle powder as a precursor and a quantitative supply device of phosphoric acid, it can be continuously processed using a crusher such as a hammer mill or pin mill. Is also possible. The added phosphate compound may be adsorbed and / or coated in any state of the phosphate compound and / or pyrophosphate ion or metaphosphate ion.

  The phosphate compound may be diluted with a solvent such as water and mixed as necessary. Moreover, after mixing a phosphoric acid compound, you may perform drying etc. as needed.

  Next, the resin composition for bonded magnets using the ferrite particle powder according to the present invention will be described.

  The resin composition for bonded magnets according to the present invention has a ferrite particle powder ratio of 70 to 95 parts by weight in the resin composition for bonded magnets, and a total amount of 30 to 5 parts by weight of the organic binder component and the silane coupling agent component. The mixture is mixed and kneaded so that the phosphorus content is 100 to 4000 mg / kg (0.010 to 0.4 wt%) as P.

  The phosphorus content is more preferably 120 to 3500 mg / kg (0.012 to 0.35% by weight) as P.

The silicon content of the bonded magnet resin composition according to the present invention is in terms of SiO ₂ 1000~10000mg / kg (0.10~1.00% by weight). When the silica content is less than 1000 mg / kg, the addition amount of the silane coupling agent is too small, the compatibility between the ferrite particle powder and the organic binder component is deteriorated, and the fluidity is lowered. If it exceeds 10,000 mg / kg, the effect is saturated, so there is no point in adding more than necessary. Preferably, it is 1100-8000 mg / kg (0.11-0.80 weight%), More preferably, it is 1200-5000 mg / kg (0.12-0.50 weight%).

  The organic binder is not particularly limited as long as it is used in conventional bonded magnets. Rubber, vinyl chloride resin, ethylene-vinyl acetate copolymer resin, ethylene-ethyl acrylate copolymer resin, PPS resin, polyamide ( Nylon) resin, polyamide elastomer, polymerized fatty acid-based polyamide and the like can be selected and used depending on the application, but when priority is given to the strength and rigidity of the molded body, a polyamide resin is suitable. Moreover, well-known mold release agents, such as a zinc stearate and a calcium stearate, can be added as needed.

  As the silane coupling agent of the present invention, those having any one of a vinyl group, an epoxy group, an amino group, a methacryl group, and a mercapto group as a functional group, and a methoxy group or an ethoxy group can be used. Has an amino group and a methoxy group or an amino group and an ethoxy group.

The residual magnetic flux density Br of the resin composition for bonded magnets according to the present invention is preferably 230 mT (2300 G) or more, more preferably 235 mT (2350 G) or more in a magnetic measurement method described later. The coercive force iHc is preferably 119 to 279 kA / m (1500 to 3500 Oe), more preferably 127 to 259 kA / m (1600 to 3250 Oe). The maximum energy product BHmax is preferably 10.3 kJ / m ³ (1.30 MGOe) or more, more preferably 10.7 kJ / m ³ (1.35 MGOe) or more.

  Next, a method for producing a bonded magnet resin composition using the ferrite particle powder, the resin binder, and the silane coupling agent according to the present invention will be described.

  The resin composition for bonded magnets according to the present invention can be obtained by a known method for producing a resin composition for bonded magnets. For example, the ferrite particle powders according to the present invention and / or commercially available ferrite particle powders for bonded magnets can be obtained. Add silane coupling agent, if necessary, phosphoric acid, etc., mix uniformly, mix uniformly with organic binder component, melt knead using kneading extruder etc., crush or cut the kneaded product into granules and pellets Can be obtained.

  The addition amount of the silane coupling agent is 0.15 to 3.5 parts by weight, preferably 0.2 parts by weight with respect to 100 parts by weight of the ferrite particle powder according to the present invention and / or commercially available ferrite for bonded magnet. Part to 3.0 parts by weight.

  The resin composition for bonded magnets according to the present invention requires that the content of the phosphate compound in the resin composition be in the above range, and when using ferrite particle powder that has not been previously treated with a phosphate compound. A predetermined amount of the phosphoric acid compound may be added either before or during mixing with the resin.

  Next, the magnet roll according to the present invention will be described.

  Magroll is a magnetic mixture of ferrite magnetic powder for bonded magnet and organic binder component, etc. in advance, and / or melted and kneaded after mixing them, pulverized into pellets or cut into a resin composition for bonded magnet in the molten state. Columnar body portions having a plurality of magnetic poles on the peripheral surface in so-called magnetic field injection molding that is injected into the magnetic field of the mold cavity and orients the magnetic powder, and shaft portions provided on both end faces of the body portion; Was obtained by integrally molding. The molded body is integrally molded having a body portion having a diameter of 17 mm and a length of 220 mm and a shaft portion having a diameter of 5.4 mm (the axis is the same as the body portion having a diameter of 17 mm) at both ends.

<Action>
It is still clear that the ferrite particle powder and / or the resin composition for bonded magnets according to the present invention contains phosphorus, so that the strength and magnetic properties of the molded body containing the ferrite are excellent and the voids are reduced. However, the present inventor estimates as follows.

  That is, the ferrite particle powder according to the present invention has the phosphate compound, pyrophosphate ion, and metaphosphate ion adsorbed and adhered to the surface, thereby solving the aggregation of the ferrite particles and improving the ferrite particle dispersion effect. Estimated.

  The resin composition for bonded magnets according to the present invention has improved dispersibility of ferrite by phosphoric acid compounds, pyrophosphate ions, and metaphosphate ions, and contains phosphoric acids, so that the reactivity between the organic binder component and the silane coupling agent is improved. It is estimated that the compatibility of the three components of ferrite, organic binder, and silane coupling agent has been improved synergistically.

  As a result, the mechanical strength is improved and the phosphoric acid compound is selected when the resin composition is kneaded or injection-molded by selecting a phosphoric acid compound that does not decompose and / or dehydrate within the molecule at 400 ° C. or lower. Since no decomposition or dehydration occurs, void formation can be suppressed when forming a molded body such as a magnet roll.

  A typical embodiment of the present invention is as follows.

  The average particle size of the ferrite particle powder according to the present invention was measured using “Powder Specific Surface Area Measuring Device SS-100” (manufactured by Shimadzu Corporation).

  The BET specific surface area of the ferrite particle powder according to the present invention was measured using “4 specimen fully automatic specific surface area measuring device 4 Sorb U2” (manufactured by Yuasa Ionics Co., Ltd.).

As the compression density of the ferrite particle powder according to the present invention, the density when the particle powder was compressed at a pressure of 1 t / cm ² was adopted.

  The phosphorus (P) content according to the present invention was obtained by acid-dissolving the powder and measuring it with a “plasma emission spectroscopic analyzer iCAP6000 series (manufactured by Thermo Electron Co., Ltd.)”.

The content of silica (SiO ₂ ) according to the present invention was determined as a content in terms of oxide (SiO ₂ ) using a fluorescent X-ray apparatus (RIX2100, manufactured by Rigaku Corporation).

The saturation magnetization value σ _s and the coercive force Hc of the ferrite particle powder are measured under the condition of a maximum magnetic field of 1591 kA / m (20 kOe) using a “sample vibration magnetometer SSM-5-15” (manufactured by Toei Kogyo Co., Ltd.) It was measured. As the saturation magnetization value σ _s , a value obtained by extrapolating the measured value obtained in each magnetic field to the magnetic field infinite by 1 / H ² plot was adopted.

  The melt mass flow rate (MFR) of the resin composition for bonded magnets was determined by melting at 270 ° C. and measuring with a 10 kg load in accordance with JIS K7210.

  The molding density of the resin composition for bonded magnets was determined by using an electronic hydrometer EW-120SG (Corporation) as the core formed by melting the bonded magnet composition in a 25 mmφ, 10.5 mm high mold. Measured by Yasuda Seiki Seisakusho).

  The moisture content of the resin composition for bonded magnets was determined by measuring with a “water vapor measuring device AQ-7” (manufactured by Hiranuma Sangyo Co., Ltd.) with a moisture vaporization accessory device EV-6 (manufactured by Hiranuma Sangyo Co., Ltd.).

  The magnetic properties (residual magnetic flux density Br, coercive force iHc, coercive force bHc, maximum energy product BHmax) of the resin composition for bonded magnets were such that the bonded magnet composition was melted in a 25 mmφ, 10.5 mm high mold. The state was determined by measuring in a magnetic field of 14 kOe using a “DC magnetization characteristic automatic recording device 3257” (manufactured by Yokogawa Hokushin Electric Co., Ltd.) after magnetic field orientation at 4 kOe.

  Injection molding using the resin composition for bonded magnets was performed using an injection molding machine 110ELII manufactured by Nippon Steel Co., Ltd., a body portion having a diameter of 17 mm and a length of 220 mm, and a diameter of 5.4 mm (the axis is the diameter). As a single-piece mag roll having both ends of the shaft part (same as 17mm body part), a mold having a set temperature of 100 ° C is magnetized in the body part into four poles such as S1, S2, N1, and N2 in an injection molding machine. It was cooled and taken out until the surface temperature of the mag roll was about 130 ° C. The injection pressure at the time of this mag roll injection molding was recorded, and the injection property was judged.

  The mechanical strength of the mag roll was determined by immersing it in water set at a water temperature of 15 ° C. using a chiller within 5 seconds after taking out the mag roll, and letting it stand for 1 hour. Autogravity AG-I series "3-point bending strength of the mag roll body part (3-point bending test in which the central part is 180 mm in distance and the central part is pressurized at a speed of 50 mm / min)" Measured by Shimadzu Corporation) and determined as bending strength.

  The magnetic properties of the mag roll were measured at a position 10 mm from the axial center using a gauss meter (model 9951 gauss meter manufactured by Bell, Axial Probe SAF 99-1802 (manufactured by Toyo Corporation)).

  The magnetic force of the mag roll was obtained as an average value of four poles by measuring the maximum magnetic flux density of S1, S2, N1, and N2 at the center of the body portion.

  The surface magnetic force uniformity of the mag roll is the same as the method described in Japanese Patent Laid-Open No. 10-340002. The axial magnetic force at the S1 pole is the above gauss meter, and the central portion of 198 mm excluding the portion from both ends to 11 mm is used. The measurement was made every 1 mm in the range, and the maximum amount of change in magnetic flux density every 1 mm was determined as the surface magnetic force uniformity.

The number of mag roll voids was evaluated according to the following procedure.
The mag roll was cut in parallel with the axial direction with a 190 mm slide marnoco manufactured by Makita Co., Ltd., and the diameters of voids existing in both cross sections thereof were measured with a ruler. The diameters of the voids were classified into four categories (less than 0.5 mm, 0.5 mm or more and less than 3.0 mm, 3.0 mm or more and less than 5.0 mm, 5.0 mm or more), and the number thereof was measured.

Example 1
<Manufacture of ferrite particle powder>
Commercially available strontium ferrite powder (average particle size is 1.52 μm, BET specific surface area is 1.38 m ² / g, compression density is 3410 kg / m ³ (3.41 g / cm ³ ), phosphorus content 83 mg / kg, SiO ₂ Content 615 mg / kg) was put in a Henschel mixer, and sodium pyrophosphate was added at 500 mg / kg based on the ferrite weight and mixed for 10 minutes.
The obtained ferrite particle powder has an average particle size of 1.59 μm, a BET specific surface area of 1.31 m ² / g, a compression density of 3380 kg / m ³ (3.38 g / cm ³ ), and a phosphorus content of 210 mg / kg. The SiO ₂ content was 615 mg / kg.

Examples 2-5, Comparative Examples 1-5:
Ferrite particle powder was prepared in the same manner as in the above-described embodiment except that the composition, the type of additive and the amount added were variously changed.
Table 1 shows the used ferrite magnetic powder, and Table 2 shows the manufacturing conditions and characteristics of the obtained magnetic powder for bond ferrite.

Example 6
<Manufacture of resin composition for bonded magnet>
25,000 g of the ferrite particle powder obtained in Example 1 was put in a Henschel mixer, and 0.3 wt% of an aminoalkyl silane coupling agent was added to the ferrite particle powder and mixed until uniform for 1 hour. After 2915 g of 6-nylon resin having a viscosity of 2.02 was added, the mixture was further mixed for 1 hour to prepare a mixture of resin compositions for bonded magnets.

  The obtained mixture of the composition for bonded magnet is quantitatively fed to a biaxial kneader and kneaded at a temperature at which 6-nylon is melted. The kneaded product is taken out as a strand and taken out into a pellet size of 2 mmφ × 3 mm. To obtain a resin composition for bonded magnets.

Examples 7-10, Comparative Examples 6-10:
A bonded magnet resin composition comprising various ferrite particle powders, 6-nylon resin, and silane coupling agent was prepared in the same manner as in Example 6 with various addition amounts of 6-nylon resin and silane coupling agent varied. .
Table 3 shows the production method and characteristics of the resin composition for bonded magnets.

Example 11
<Magroll molding>
After the bonded magnet resin composition obtained in Example 6 was dried at 100 ° C. for 8 hours, the bonded magnet resin composition was melted at 315 ° C. in an injection molding machine, and the injection time was set to 100 ° C. in 1 second. An integrally molded mag roll having a body portion having a diameter of 17 mm and a length of 220 mm and a shaft portion having a diameter of 5.4 mm (the axis is the same as the body portion having a diameter of 17 mm) at both ends was prepared.

Examples 12-15, Comparative Examples 11-15:
Magnet rolls were prepared in the same manner as in Example 11 using various resin compositions for bonded magnets. Table 4 shows the injection properties and various properties of the mag roll.

  The mag roll according to the present invention has a diameter of 17 mm, the mag roll strength cooled with water at 15 ° C. is 500 N or more, the mag roll magnetic force is 800 G or more (80 mT or more), and the surface uniformity of the mag roll magnetic force (every 1 mm). The maximum amount of change in the magnetic flux density) is 0.70% or less of the magroll magnetic force, and in particular, even at a high melting temperature and molding temperature, it can cause mechanical strength and mechanical strength reduction ( 3.0 mm or more), that is, the number of voids was reduced, and the surface uniformity of the magnetic force was confirmed to be superior to that of the comparative example.

  Therefore, by using a phosphoric acid compound that does not decompose and / or cause intramolecular dehydration in the temperature range of 200 to 400 ° C., a molded product such as mag roll can be produced at a higher temperature, and the fluidity during shaping is improved. Because it is excellent, productivity is also improved.

Since the bonded magnet manufactured using the ferrite particle powder and / or the resin composition for bonded magnet according to the present invention is excellent in quenching resistance (bending strength of quenching) and magnetic characteristics (uniformity of magnetic force), the bonded magnet, in particular, mag roll. It is suitable as a ferrite particle powder and / or a resin composition for bonded magnets.

Claims (6)

In the ferrite particle powder for bonded magnet in which a phosphate compound is adsorbed and / or contained, the phosphate compound is a phosphate compound that does not decompose and / or dehydrate in the molecule at 200 to 400 ° C. the content of the phosphorus compound, 120~ 1610 mg / kg ferrite particles for bonded magnet, which is a (0.012 to 0.161 wt%) as a P. A resin composition for bonded magnets comprising an organic binder component, ferrite particle powder for bonded magnet and a phosphoric acid compound, wherein the content of the ferrite particle powder is 70 to 95% by weight with respect to the resin composition for bonded magnet The phosphoric acid compound is a phosphoric acid compound that does not undergo decomposition and / or intramolecular dehydration at 200 to 400 ° C., and the phosphoric acid compound content is 100 to 1440 mg / kg (0.010 to 0.144) as P. % By weight). A resin composition for bonded magnets. A bonded magnet resin composition comprising an organic binder component, a bonded magnet ferrite particle powder, a phosphoric acid compound and a silane coupling agent, wherein the content of the ferrite particle powder is from 70 to 70 based on the bonded magnet resin composition. The phosphoric acid compound is 95% by weight, and the phosphoric acid compound does not undergo decomposition and / or intramolecular dehydration at 200 to 400 ° C., and the phosphoric acid compound content is 100 to 1440 mg / kg (0. 10000 to 0.144 % by weight), and the silicon content is 1000 to 10,000 mg / kg (0.10 to 1.0% by weight) as SiO ₂ . 4. The resin composition for bonded magnets according to claim 2, wherein the organic binder component is a polyamide resin. 5. A molded body comprising the ferrite particle powder for bonded magnet according to claim 1 or the resin composition for bonded magnet according to any one of claims 2 to 4. 6. The molded body according to claim 5, wherein the molded body is a magnet roll.