JPH01239817A - Ferromagnetic metal powder, manufacture thereof and magnetic recording medium using the same powder - Google Patents

Abstract

PURPOSE:To sufficiently improve magnetic characteristics and durability and to sufficiently improve the magnetic characteristic, electromagnetic conversion characteristic and durability of a magnetic recording medium obtained by using ferromagnetic metal powder containing iron as a main ingredient by incorporat ing aluminum, silicon and phosphorus in the powder containing as the main ingredient the iron. CONSTITUTION:Ferromagnetic metal powder containing as a main ingredient contains aluminium, silicon and phosphorus. In this instance, 0.2-15.0wt.% of aluminium, 0.05-15.0wt.% of silicon and 0.05-5.5wt.% of phosphorus are contained based on the iron, and it is preferable that more aluminium, silicon and phosphorus are present on the surface of the powder particles. Further, the surfaces of oxyhydroxide particles of oxide particles containing as a main ingredient iron are treated with aluminum compound, silicon compound and phosphorus compound to be covered therewith, then thermally reduced in a reducing gas atmosphere to incorporate aluminium, silicon and phosphorus in the particles, thereby manufacturing the ferromagnetic metal powder.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a ferromagnetic metal powder suitable for high-density recording, a method for producing the same, and a magnetic recording medium using this ferromagnetic metal powder as a recording element. , For more details, see (〃
The present invention relates to a ferromagnetic metal powder with excellent feelability and durability, a method for producing the same, and a magnetic recording medium with excellent magnetic properties, electromagnetic conversion properties, and durability obtained using the ferromagnetic metal powder.

(Conventional Techniques) Ferromagnetic metal powders conventionally used in magnetic recording media suitable for high-density recording, for example, in the case of ferromagnetic metal iron powder, are manufactured by heating and reducing iron oxyhydroxide or iron oxide. At this time, sintering occurs between particles, which tends to impair the uniformity and shape of the particles, making it difficult to obtain sufficiently excellent magnetic properties and durability.

Therefore, as a method to prevent sintering between iron oxyhydroxide particles or iron oxide particles, ferromagnetic metal powder is produced by depositing a silicon compound or an aluminum compound on the surface of these particles and then reducing the particles by heating. things are being done. (
(Japanese Patent Publication No. 56-28697, Japanese Patent Publication No. 60-17802, Japanese Patent Publication No. 59-19168) In the method of treating the surface of ferromagnetic metal powder ()ability and durability are not sufficiently improved.
As a result, magnetic recording media obtained using the same do not have sufficiently improved magnetic properties, electromagnetic conversion properties, and durability.

(Means for Solving the Problems) In view of the current situation, this invention was made as a result of various studies, and it is an object of the present invention to replace the surface of oxyhydroxide particles or oxide particles mainly composed of iron with aluminum compounds and silicon. By treating with a compound and a phosphorus compound, oxyhydroxide particles or oxide particles mainly composed of iron can be primary dispersed, and at the same time, an aluminum compound, a silicon compound, and a phosphorus compound can be uniformly deposited on the surface of the oxyhydroxide particles or oxide particles. The magnetic properties and durability of the ferromagnetic metal powder obtained by heating and reducing the powder in a reducing gas atmosphere have been sufficiently improved. The magnetic properties, electromagnetic conversion properties, and durability of the recording medium are sufficiently improved.

In this invention, the strong (d) metal powder containing iron as a main ingredient and containing aluminum, silicon, and phosphorus has a surface of oxyhydroxide particles or oxide particles containing iron as a main ingredient.
It is obtained by treating with an aluminum compound, a silicon compound, and a phosphorus compound, uniformly depositing the aluminum compound, silicon compound, and phosphorus compound, and then heating and reducing it in a reducing gas atmosphere. Since the surface of the oxyhydroxide particles or oxide particles is treated with a phosphorus compound, agglomeration between these particles is effectively prevented and primary dispersion is performed well, allowing aluminum compounds, silicon compounds, and phosphorus to be separated. The compound is evenly deposited. As a result, sintering during thermal reduction is effectively prevented, and a ferromagnetic metal powder with good uniformity and shape can be obtained. Therefore, the magnetic properties and durability of the ferromagnetic metal powder are sufficiently improved, and the magnetic recording medium obtained using the same is sufficiently improved in magnetic properties, electromagnetic conversion properties, and durability.

Here, the method of treating the surface of oxyhydroxide particles or oxide particles mainly composed of iron with an aluminum compound, a silicon compound, and a phosphorus compound is not particularly limited. When the surface of the oxyhydroxide particles or oxide particles to be treated is immersed in a solution containing a phosphorus compound, and then treated by adding an aluminum compound and a silicon compound to this treatment solution, the surface of the oxyhydroxide particle or oxide particle is treated by adding an aluminum compound and a silicon compound to this treatment solution. Agglomeration between iron-based oxyhydroxide particles or oxide particles is effectively prevented, and the aluminum compound and silicon compound to be deposited later are uniformly deposited by being dispersed. Therefore, it is preferable to first treat with a phosphorus compound and then with an aluminum compound and a silicon compound. In addition, the treatment with an aluminum compound and the treatment with a silicon compound may be performed separately rather than simultaneously, and in this case, either may occur first. Excellent adhesion to particles or oxide particles, and
It binds well to aluminum compounds, and furthermore, aluminum compounds form a relatively hard and strong coating on the particle surfaces, so it is preferable to first deposit a silicon compound and then deposit an aluminum compound. In addition, these phosphorus compounds, silicon compounds, and aluminum compounds are coated on the surface of iron-based oxyhydroxide particles or oxide particles, and reduced after coating to form ferromagnetic metal powder. It is preferable to contain it so that it is present in a large amount on the surface of the surface.

In this way, when the surface of iron-based oxyhydroxide particles or oxide particles is treated with a phosphorus compound, an aluminum compound, and a silicon compound, the iron-based oxyhydroxide particles are formed by the adhesion of the phosphorus compound. Agglomeration between particles or oxide particles is effectively prevented, primary dispersion is performed well, the aluminum compound and silicon compound are uniformly deposited, and sintering during thermal reduction is well prevented.
A ferromagnetic metal powder with good uniformity and shape and excellent dispersibility in a binder resin can be obtained. Furthermore, since the aluminum compound adhered to the particle surface has excellent hardness, the surface hardness of the ferromagnetic metal powder becomes high, and the durability is sufficiently improved. Furthermore, since this aluminum compound has excellent affinity with the binder resin, the dispersibility of the ferromagnetic metal powder in the binder resin is sufficiently improved.

Therefore, when the ferromagnetic metal powder obtained in this way is used in a magnetic recording medium, the dispersibility in the binder resin is improved, and the magnetic properties and electromagnetic conversion properties are sufficiently improved. The aluminum compound, which has excellent hardness on the surface of the powder particles, exhibits an excellent polishing effect, forms a strong magnetic layer, and sufficiently improves the durability of the magnetic recording medium.

The silicon compounds, aluminum compounds and phosphorus compounds deposited on the particle surfaces of such ferromagnetic metal powders are
Preferably, they are oxides, hydrous oxides, or oxide salts of silicon, aluminum, or phosphorus. In addition, in the case of silicon compounds, the content of these is 0.05 to 15% relative to iron.
．． It is preferably within the range of 0% by weight, more preferably within the range of 2 to 10% by weight, and more preferably within the range of 5 to 7% by weight. In the case of aluminum compounds, the amount should be within the range of 0.2 to 15.0% by weight based on iron, and further 0.2% to 15.0% by weight based on iron.
It is preferably within the range of 5 to 10% by weight, and 1 to 10% by weight.
It is more preferable to keep it within the range of % by weight. Furthermore, in the case of phosphorus compounds, the amount is within the range of 0.05 to 5.0% by weight based on iron, preferably within the range of 0.2 to 5% by weight, and 0.3 to 3% by weight. It is preferable to keep it inside.

In addition, in addition to depositing the silicon compound, aluminum compound, and phosphorus compound in this way, other compounds such as organic substances and organometallic compounds are further deposited within the range that does not impair the binding force with the binder...fat. There is no problem in modifying a part of the particle surface of the ferromagnetic metal powder.

The production of magnetic recording media that uses ferromagnetic metal powder mainly composed of iron but also containing silicon, aluminum, and phosphorus as a magnetic recording element is carried out according to conventional methods. A magnetic paint is prepared by dispersing and mixing the powder with a binder resin, an organic solvent, and other necessary components, and this magnetic paint is applied onto a substrate such as a polyester film by any means such as spraying or roll coating, This is done by methods such as drying.

Here, as the binder resin, polyvinyl chloride resin,
A wide range of conventional binder resins are used, including vinyl chloride-vinyl acetate copolymers, cellulose resins, butyral resins, polyurethane resins, polyester resins, epoxy resins, polyether resins, and isocyanate compounds. used.

Examples of organic solvents include ketone solvents such as cyclohexanone, methyl ethyl ketone, and methyl isobutyl ketone, ester solvents such as ethyl acetate and butyl acetate, aromatic hydrocarbon solvents such as benzene, toluene, and xylene, and sulfoxides such as dimethyl sulfoxide. solvent,
Solvents suitable for dissolving the binder resin used, such as ether solvents such as tetrahydrofuran and dioxane, may be used alone or in combination of two or more without particular limitation.

In addition, various additives commonly used in magnetic paints,
For example, a dispersant, a lubricant, an abrasive, an antistatic agent, etc. may be added as appropriate.

(Example〕 Next, embodiments of the invention will be described.

Example 1 1 g of tripolyphosphoric acid was added and dissolved in 3P of pure water, and α-FeOOH (major axis 0.5 μm, needle ratio 15
/1) 50g was added and well dispersed. Next, while thoroughly stirring this suspension with a stirrer, Na4S i0
4 13 g, A l 2 (S O4), 88, and N
Ten volumes of an aqueous NaOH solution in which 4 g of aOH had been dissolved were added to form a film consisting of a phosphorus compound, a silicon compound, and an aluminum compound on the surface of the α-FeOOH particles.

Next, the α-FeOOH film formed thereon was washed with water, dried, and then reduced in a hydrogen stream at 500° C. for 8 hours. After reduction, the surface layer of the powder particles was gradually oxidized and stabilized to obtain a strong metallic iron powder having a coating consisting of a phosphorus compound, a silicon compound, and an aluminum compound.

Using the ferromagnetic metal iron powder obtained in this way, 100 parts by weight of ferromagnetic metal iron powder VAGH
(Manufactured by U.C.C., vinyl chloride 10-vinyl acetate-vinyl alcohol copolymer) Bandex T-5201 (large 6, manufactured by Nippon Ink Chemical Co., Ltd., polyurethane) Myristic acid 5 H3-50
0 (manufactured by Asahi Denka Co., Ltd., 1 carbon black) Methyl isobutyl ketone 85 toluene
85〃composition consisting of 3
The mixture was placed in a 2-capacity steel ball mill and rotated for 72 hours to ensure good dispersion to prepare a magnetic paste.

Thereafter, 40 parts by weight of toluene and 2 parts by weight of Coro 2-)L (manufactured by Takeda Pharmaceutical Company, trifunctional low molecular weight isocyanate compound) were further added to this magnetic paste to prepare a magnetic paint. This magnetic paint was applied onto a polyester film with a thickness of 12 μm so that the coating thickness after drying was 4 μm, dried, mirror-finished, and then cut into 1/2 inch width to make magnetic tape. Ta.

Example 2 1 g of tripolyphosphoric acid was added and dissolved in pure water 32, and α-FeOOH (major axis 0.5 μm, needle ratio 15
/1) 50g was added and well dispersed. Next, while thoroughly stirring this suspension with a stirrer, Na. 5i04
100 ml of an aqueous solution in which 13 g of α-FeOOH was dissolved was added while bubbling CO□ into the solution, thereby forming a film consisting of a phosphorus compound and a silicon compound on the surface of the α-FeOOH particles. Next, after washing and drying the α-FeOOH film that formed the film, it was dispersed in a solution of 1 g of tripolyphosphoric acid dissolved in pure water 32, and while stirring this suspension thoroughly with a stirrer, Alz(sO4):, 20g
and 10 g of NaOH aqueous solution in which 10 g of NaOH was dissolved.
0 ml was added to the solution while CO□ was aerated into the solution, to further form a coating consisting of a phosphorus compound and an aluminum compound on the surface of the α-FeOOH particles on which a coating consisting of a phosphorus compound and a silicon compound had been formed.

The α-FeOOH with a coating formed in this way is heated and reduced in the same manner as in Example 1, and the surface layer of the powder particles is gradually stabilized by oxidation. A magnetic metal iron powder was obtained, and the same amount as in Example 1 was used in the composition of the magnetic paint in Example 1, except that the same amount of this ferromagnetic metal iron powder was used in place of the ferromagnetic metal iron powder used in Example 1. Magnetic tape was made in the same way.

Comparative Example 1 A ferromagnetic metal iron powder having a coating made of an aluminum compound and a silicon compound on the surface was produced in the same manner as in Example 1 except that the addition of tripolyphosphoric acid was omitted in the production of the ferromagnetic metal iron powder in Example 1. In addition, this ferromagnetic metal iron powder was used in the same amount as in Example 1 in place of the ferromagnetic metal iron powder used in Example 1 in the composition of the magnetic paint in Example 1. I made magnetic tape.

Comparative Example 2 A ferromagnetic metal iron powder having a coating made of an aluminum compound and a silicon compound on the surface was produced in the same manner as in Example 2 except that the addition of tripolyphosphoric acid was omitted in the production of the ferromagnetic metal iron powder in Example 2. The same method as in Example 2 was obtained, except that the same amount of this strong magnetic metal iron powder was used in place of the ferromagnetic metal iron powder used in Example 2 in the composition of the magnetic paint in Example 2. and made magnetic tape.

Comparative Example 3 1 g of tripolyphosphoric acid was added to pure water 31 and dissolved, and α-FeOOH (longer diameter 0.5 μm, needle ratio 15
/1) 50g was added and well dispersed. Next, while thoroughly stirring this suspension with a stirrer, Na4S 104
Add 100ml of an aqueous solution containing 30g of CO7 into the liquid.
was added with ventilation to form a film consisting of a phosphorus compound and a silicon compound on the surface of the α-FeOOH particles.

α-FeOOH with a coating formed in this manner is heated and reduced in the same manner as in Example 1, and the surface layer of the powder particles is gradually stabilized by oxidation to form a ferromagnetic metallic iron having a coating consisting of a phosphorus compound and a silicon compound. A powder was obtained, and the same amount as in Example 1 was used except that this ferromagnetic metal iron powder was used in the same amount in place of the ferromagnetic metal iron powder used in Example 1 in the composition of the magnetic paint in Example 1. I made magnetic tape.

Comparative Example 4 In the production of ferromagnetic metal iron powder in Comparative Example 3, N
A ferromagnetic metal iron powder with a coating made of a phosphorus compound and an aluminum compound formed on the particle surface was obtained in the same manner as in Comparative Example 3, except that the same amount of A 12 (S 04) 3 was used in place of a4SiO4, and this A magnetic tape was produced in the same manner as in Comparative Example 3, except that the same amount of ferromagnetic metallic iron powder was used in place of the ferromagnetic metallic iron powder used in Comparative Example 3 in the composition of the magnetic paint in Comparative Example 3.

Regarding the ferromagnetic metal powder obtained in each Example and Comparative Example, the contents of AI, Si, and P were examined, and the coercive force, saturation magnetization amount, and square shape were measured. In addition, the coercive force, squareness, and RF specific output of the magnetic recording media obtained in each example and comparative example were measured, and the durability was investigated. After recording a signal with an RF specific output of 5 MHz at a constant level, the output when reproduced was measured and expressed as a relative value with the magnetic tape of Comparative Example 1 being 7J*(OaB). In addition, durability was measured using a commercially available VTR.
The determination was made by measuring the time until the output decreases by 3 dB when a still image is reproduced in a constant temperature room at -5°C.

Table 1 below shows the results.

〔Effect of the invention〕

As is clear from Table 1 above, the ferromagnetic metallic iron powders obtained in the present invention (Examples 1 and 2) are both lower than the ferromagnetic metallic iron powders obtained in Comparative Examples 1 to 4. The magnetic tapes obtained by the present invention (Examples 1 and 2) have high coercive force, high saturation magnetization, and high squareness, and have higher squareness than the conventional magnetic tapes obtained in Comparative Examples 1 to 4. The ferromagnetic metal iron powder obtained by this invention has excellent magnetic properties and durability, and as a result, the ferromagnetic metal iron powder obtained by this invention has excellent magnetic properties and durability. It can be seen that the magnetic recording medium obtained has further improved magnetic properties, electromagnetic conversion properties, and durability.

Patent applicant: Hitachi Maxell, Ltd.

Claims (8)

[Claims] 1. A ferromagnetic metal powder containing aluminum, silicon, and phosphorus in a ferromagnetic metal powder mainly composed of iron. 2. Based on iron, aluminum is 0.2 to 15.0% by weight, silicon is 0.05 to 15.0% by weight, and phosphorus is 0.0%.
The ferromagnetic metal powder according to claim 1, containing the ferromagnetic metal powder in a range of 5 to 5.0% by weight. 3. 3. The ferromagnetic metal powder according to claim 1, wherein more aluminum, silicon, and phosphorus are present on the particle surface of the ferromagnetic metal powder. 4. The surface of iron-based oxyhydroxide particles or oxide particles is treated with an aluminum compound, a silicon compound, and a phosphorus compound to deposit the aluminum compound, silicon compound, and phosphorus compound, and then this is reduced. 1. A method for producing ferromagnetic metal powder, characterized in that aluminum, silicon, and phosphorus are contained in the particles by thermal reduction in a magnetic gas atmosphere. 5. Aluminum content is 0.2 to 15 compared to iron.
．． 5. The method for producing ferromagnetic metal powder according to claim 4, wherein the silicon content is within the range of 0.05 to 15.0 wt%, and the phosphorus content is within the range of 0.05 to 5.0 wt%. . 6. A magnetic recording medium characterized in that a magnetic layer contains a ferromagnetic metal powder mainly composed of iron and containing aluminum, silicon, and phosphorus. 7. The ferromagnetic metal powder contained in the magnetic layer contains 0.2 to 15.0% by weight of aluminum and 0% of silicon, based on iron.
．． Claim 6: The ferromagnetic metal powder contains phosphorus in the range of 0.05 to 15.0% by weight and phosphorus in the range of 0.05 to 5.0% by weight.
The magnetic recording medium described. 8. Claims 6 and 7, wherein the ferromagnetic metal powder contained in the magnetic layer is a ferromagnetic metal powder in which more aluminum, silicon, and phosphorus are present on the particle surface of the ferromagnetic metal powder.
The magnetic recording medium described.