JPS5810845B2 - Soleumocchia japonica japonica - Google Patents

Description

Detailed Description of the Invention The present invention relates to ferromagnetic metal particles and magnetic recording media using the same, and in particular to ferromagnetic metal particles having high coercive force and high saturation magnetization and magnetic recording suitable for high-density recording. It's about the medium.

Ferromagnetic powders conventionally used in magnetic recording media include maghemite, cobalt-doped maghemite, magnetite, cobalt-doped magnetite,
These included a bertholed compound of maghemite and magnetite, a bertholed compound of maghemite and magnetite doped with cobalt, and chromium dioxide.

However, the magnetic properties of these ferromagnetic powders, such as coercive force (He) and maximum residual magnetic flux density (Br), are insufficient for use in so-called high-density recording. ), it was not suitable for magnetic recording with a narrow track width (approximately 100 μm or less).

Recently, ferromagnetic powders with properties suitable for high-density recording have been actively developed, and one of the target materials is ferromagnetic metal powder.

The following methods are known as methods for producing ferromagnetic metal powder.

1) A method of thermally decomposing an organic acid salt of a ferromagnetic metal and reducing it with a reducing gas [for example, Japanese Patent Publication No. 36-11412,
No. 36-22230, No. 38-14809, No. 39
-3807, 40-8026, 40-8027
No. 40-15167, No. 40-16899 (U.S. Patent No. 3186829), No. 4112096, No. 4
No. 1-14818 (US Patent No. 3190748), No. 4
No. 2-24032, No. 43-3221, No. 43-22
No. 394, No. 43-29268, No. 44-4471, No. 44-27942, No. 46-38755, No. 4
No. 7-38417, No. 47-41158, No. 48-2
No. 9280, Japanese Unexamined Patent Publication No. 47-38523, etc.].

2) A method for reducing acicular oxyhydroxides, their compounds containing other metals, or acicular iron oxides obtained from these oxyhydroxides [for example,
No. 3862, No. 37-11520, No. 39-2033
No. 5, No. 39-20939, No. 46-24833,
No. 47-29706, No. 47-30477 (U.S. Patent No. 3598568), No. 47-39477, No. 48
No.-24952, No. 49-7313, JP-A-46-5
No. 057 (U.S. Patent No. 3,634,063), No. 46-71
No. 53, US Pat. No. 48-79153, US Pat. No. 48-82395, US Pat. No. 3,607,220, US Pat. No. 3,607,219, US Pat.

3) Method of evaporating ferromagnetic metal in low pressure inert gas [for example, Japanese Patent Publication No. 46-25620, No. 47-41
No. 31, No. 47-27718, No. 49-45320, No. 49-18160, JP-A No. 48-25662,
No. 48-25663, No. 48-25664, No. 48
-25665, 48-31166, 48-55
No. 400, Publication No. 48-81092, etc.].

4) Method of thermally decomposing metal carbonyl compounds [for example, Japanese Patent Publication No. 39-1004, Japanese Patent Publication No. 40-3415, Japanese Patent Publication No. 4
No. 5-16868, No. 49-26799, U.S. Patent 2
No. 983997, No. 3172776, No. 320000
No. 7, No. 3228882, etc.].

5) After electrodepositing ferromagnetic metal powder using a mercury cathode,
Method of separating from mercury [For example, Japanese Patent Publication No. 35-1291
No. 0, No. 36-3860, No. 36-5513, No. 3
No. 9-787, No. 39-15525, No. 40-812
No. 3, No. 40-9605 (US Pat. No. 3,198,717), No. 45-19661 (US Pat. No. 3,156,650), US Pat. No. 3,262,812, etc.].

6) A method of reducing by adding a reducing agent to a solution containing a salt of a ferromagnetic metal [for example, Japanese Patent Publications No. 38-20520, No. 38-26555, No. 43-20116, No. 4
No. 5-9869, No. 45-14934, No. 47-78
No. 20, No. 47-16052, No. 47-41718, No. 47-41719 (US Patent No. 3607218)
, Japanese Patent Application Publication No. 47-1353 (US Pat. No. 3,756,866)
), No. 47-1363, No. 47-42252, No. 47-42253, No. 48-44194, No. 48-
No. 79754, No. 48-82396, U.S. Patent No. 320
No. 6338, No. 3494760, No. 3535104, No. 3567525, No. 3661556, No. 366
No. 3318, No. 3669643, No. 3672867, No. 3726664, etc.).

The present invention relates to ferromagnetic metal powders obtained by the methods described above.

The ferromagnetic metal particles of the present invention can be sintered to form a permanent magnet,
A metal thin film magnetic layer is provided on the support by a vapor deposition method (vacuum deposition method, sputtering method, ion blating method, ion beam deposition method, etc.), or a magnetic layer mixed and dispersed with a binder is provided on the support. It is possible to provide a magnetic recording medium.

As a result of the study, it was found that the metal content of ferromagnetic metal powder is 0,2
wt, %~5. It has been found that by containing Owt% sulfur, it is possible to increase the coercive force and make it easier to control, and also prevents the saturation magnetization (σS) from decreasing during the process and maintains a high value. Ta.

When the sulfur content is below 0.2 wt.%, high He
The effect of high σS cannot be obtained.

Also, 5. When Owt-1 or more, the coercive force decreases and σS is similarly low, so the effect of sulfur content disappears.

Furthermore, as the amount of sulfur increases to 5 wt, 1 or more, the ferromagnetic metal powder becomes susceptible to moisture, and in a humid atmosphere, σ
It was observed that S decreased drastically.

That is, the ferromagnetic metal powder of the present invention contains sulfur in the range of 0.2 wt, 1 to 5 wt, % based on the metal content, particularly preferably 0.5 wt,
%~2wt.

More specifically, 75 wt of the ferromagnetic metal powder, preferably 80 wt or more, is metal;
-Co, Fe-Ni, Co-Ni, Fe
-Co-Ni; More preferably, Fe is the main component among them; Sulfur is contained in a metal content of 0.2 wt, 1 to 5.0 wt%; Other metal content: 0.01 wt, % ~1
9.8 wt, % Cr, P, B, Pb.

Sn, Zn, Ti, Mo, MntAgycu, Bi
the particle size in the minor axis direction (breadth direction) is 50X to 1ooOX, more preferably 150X to 400X.

The first object of the present invention is to provide ferromagnetic metal particles having high coercive force.

The second objective is to provide ferromagnetic metal particles with high saturation magnetization.

The third objective is to provide a magnetic recording medium suitable for high-density recording.

A fourth object is to provide a magnetic recording medium that reduces head wear.

The fifth object is to provide a method for obtaining ferromagnetic metal particles whose coercive force can be stably adjusted using a simple method.

As a method for producing such a ferromagnetic metal powder, for example, since it can be easily obtained by the above-mentioned production method 6), the method 6) in which a salt of a ferromagnetic metal is reduced in its solution will be explained.

As reducing agents, acids and salts containing phosphinate ions; borohydride compounds and their derivatives such as sodium borohydride and diethylaminoborane; hydrazine and its derivatives; Mg, Ca, Al, etc. (D metal powder etc. are used) .

Examples of ferromagnetic metal salts include Fe and Co.

Fe-Co, Fe-Ni, Co-Ni, F
A salt containing either e-Co-Ni is used.

The salt may be either organic or inorganic, and for example, sulfates, chlorides, nitrates, formates, acetates, and sulfaminates are used.

By using a bath to which a sulfur compound is added in addition to these elements, a sulfur-containing ferromagnetic metal powder can be obtained.

As the sulfur compound, dithionite, thiosulfate, thionate, sulfide, etc. are used.

Additionally, Ag and Cr are added to improve the oxidation resistance of the sulfur-containing ferromagnetic metal powder.

It is preferable to add compounds such as Pb, Zn, Sn, Ti, Mo, Cu, Bi, and Mn.

A method different from method 6) above, such as 1) above,
In method 2), the ferromagnetic metal particles of the present invention can be obtained by mixing sulfur and reducing the mixture in a high-temperature reducing atmosphere.

Specific examples of the present invention are shown below.

Figure 1 shows ferromagnetic particles obtained by reacting an aqueous solution containing ferrous chloride, cobalt chloride, potassium chromium sulfate, and sodium hydrosulfide with an aqueous solution containing sodium borohydride in a magnetic field, and ferromagnetic particles obtained using these particles. This is the magnetic property of magnetic tape.

The horizontal axis is the sulfur content (sulfur/metal content x 100wt,
%), and the vertical axis shows the coercive force (Hc; Oe″rsteds
) and saturation magnetization (σs: emu/l).

The magnetic force (He) is as shown by curve I when the sulfur content is 0.2 to 5. High coercive force was obtained in the range of Owt, %.

Further, the saturation magnetization (σS) similarly shows a high value within the range of sulfur content of 0.2 to 5 wt.%, as shown by curve ①.

It can be said that it is particularly effective when the sulfur content is within the range of 0.5 to 2 wt.%.

The analysis results for each powder in FIG. 1 were as follows.

Iron is 56.4 wt.% and cobalt is 25.6 wt.
Ion chromium is 1, Owt, %s boron is 3.1 wt,
%.

Sulfur is 0.1-10. It was within the range of Owt,%.

The ferromagnetic metal powder of the present invention obtained by the above method is dispersed with a binder, coated on a substrate (support) using an organic solvent, and dried to form a magnetic layer to obtain a magnetic recording medium.

Regarding the manufacturing method of the magnetic paint used in the present invention,
-186, 47-28043, 47-28045, 47-28046, 47-28048, 47-3
It is described in detail in publications such as No. 1445.

The magnetic paints described in these documents mainly contain ferromagnetic powder, binder, and coating solvent, and may also contain additives such as dispersants, lubricants, abrasives, and antistatic agents.

As the binder used in the present invention, conventionally known thermoplastic resins, thermosetting resins, reactive resins, and mixtures thereof are used.

As a thermoplastic resin, the softening temperature is 150°C or less, the average molecular weight is 10,000 to 200,000, and the degree of polymerization is about 200 to 2.
For example, vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride copolymer, vinyl chloride acrylonitrile copolymer, acrylic acid ester acrylonitrile copolymer, acrylic acid ester vinylidene chloride copolymer, acrylic ester Styrene copolymer, methacrylic acid ester acrylonitrile copolymer, methacrylic acid ester vinylidene chloride copolymer, methacrylic acid ester styrene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride acrylonitrile copolymer, butadiene acrylonitrile copolymer Coalescence, polyamide resin, polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose triacetate, cellulose glopionate, nitrocellulose, etc.)
, styrene-butadiene copolymer, polyester resin, chlorovinyl ether acrylate copolymer, amine resin, various synthetic rubber-based thermoplastic resins, and mixtures thereof.

Examples of these resins are given in Japanese Patent Publication No. 37-6877, 39-
No. 12528, No. 39-19282, No. 40-5349, No. 40-20907, No. 41-9453, No. 41-14
No. 059, No. 41-16985, No. 42-6428, 4
No. 2-11521, No. 43-4623, No. 43-1520
No. 6, No. 44-2889, No. 44-17947, 44-
No. 18232, No. 45-14020, No. 45-14500
No., 47-18573, 47-22063, 47-
No. 22064, No. 47-22068, No. 47-22069
No. 47-22070, 47-27886, U.S. Patent No. 3144352, U.S. Patent No. 3419420, U.S. Pat.
No. 789, No. 3713887, etc.

The thermosetting resin or reactive resin has a molecular weight of 200,000 or less in the state of a coating liquid, and when heated after coating and drying, the molecular weight becomes infinite due to reactions such as condensation and addition.

Also, among these resins, those that do not soften or melt before the resin is thermally decomposed are preferred.

Specifically, for example, phenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, silicone resin, acrylic reaction resin, epoxy-polyamide resin, nitrocellulose melamine resin,
Mixtures of high molecular weight polyester resins and incyanate prepolymers, mixtures of methacrylate copolymers and diisocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, low molecular weight glycols/high molecular weight diols/triphenylmethane triisocyanates mixtures of polyamine resins, polyamine resins, and mixtures thereof.

Examples of these resins are given in Japanese Patent Publication No. 39-8103, 40-
No. 9779, No. 41-7192, No. 41-8016, 4
1-14275, 42-18179, 43-120
No. 81, No. 44-28023, No. 45-14501, 4
No. 5-24912, No. 46-13103, No. 47-220
No. 65, No. 47-22066, No. 47-22067, 4
No. 7-22072, No. 47-22073, No. 47-280
No. 45, No. 47-28922, U.S. Pat. No. 3,144,353, U.S. Pat. No. 3,320
No. 090, No. 3437510, No. 3597273,
It is described in No. 3781210, No. 3781211, etc.

These binders may be used alone or in combination;
Other additives may be added.

The mixing ratio of the ferromagnetic powder and the binder is in the range of 10 to 200 parts by weight per 100 parts by weight of the ferromagnetic powder.

Additives include dispersants, lubricants, abrasives, and the like.

As dispersants or stabilizers, cab9uric acid, capric acid,
Fatty acids with 12 to 18 carbon atoms (R
ICOOHXRl is an alkyl group with 11 to 17 carbon atoms)
; Alkali metals (Li, Na, etc.) or alkaline earth gold Jr4 (Mg, Ca, B, etc.) of the above fatty acids;
metal soap consisting of a); lecithin, etc. are used.

In addition, higher alcohols having 12 or more carbon atoms and sulfuric esters thereof can also be used.

These dispersants are used in an amount of 1 to 20 parts by weight per 100 parts by weight of the binder.
It is added in a range of parts by weight.

As a lubricant, silicone oil, carbon black, graphite, carbon black graft polymer, molybdenum disulfide, tungsten disulfide, carbon number 12-16
fatty acid esters consisting of a monobasic fatty acid and a monohydric alcohol with 3 to 12 carbon atoms, a monobasic fatty acid with 17 or more carbon atoms, and a total of 2 carbon atoms in the fatty acid.
Fatty acid esters consisting of 1 to 23 monohydric alcohols can be used.

These lubricants are used in amounts of 0.2 to 100 parts by weight of binder.
It is added in an amount of 20 parts by weight.

Regarding these, Japanese Patent Publication No. 43-23889, Japanese Patent Application No. 42-28647, Japanese Patent Application No. 43-81543, U.S. Patent Nos. 3470021, 3492235, 349
No. 7411, No. 3523086, No. 362576
No. 0, No. 3630772, No. 3634253,
Specifications such as No. 3637539 and No. 3687725, IBM Technical Disclosure
e Bulletion Vol. 9, A 7.
Page779, December, 1966
, and ELECTRONIK 1961. A12, P
It is described in the neglect of age380 etc.

Commonly used abrasive materials include fused alumina,
Silicon carbide, chromium oxide, corundum, artificial corundum, diamond, artificial diamond, garnet, emery (main components: corundum and magnetite), etc. are used.

These abrasives have an average particle diameter of 0.05 to 5 .mu.m, preferably 0.1 to 2 .mu.m.

These abrasives are used in an amount of 7 to 20 parts by weight per 100 parts by weight of the binder.
It is added in a range of parts by weight.

Regarding these, Japanese Patent Application No. 48-26749, U.S. Patent Nos. 3007807, 3041196, and 32
No. 93066, No. 3630910, No. 3687725
No., British Patent No. 1145349, West German Patent No. 853211
It is stated in the number etc.

The magnetic recording layer has the above composition dissolved in an organic solvent and applied as a coating solution onto a support.

In the case of a sheet or tape, the support has a thickness of about 5 to 50 μm, preferably about 10 to 40 μm, and materials include polyesters such as polyethylene terephthalate, polyolefins such as polypropylene, and cellulose derivatives such as cellulose triacetate and cellulose diacetate. , polycarbonate, etc. are used.

However, a rigid base material of metal may be more suitable for some applications.

Methods for applying the magnetic recording layer on the support include air doctor coating, gray code, air knife coating, squeeze coating, impregnation coating, reverse roll coating, druspher roll coating, gravure coating, kiss coating, cast coating, Spray coating, etc. can be used, and other methods are also possible, and detailed explanations of these methods are given in "Coating Engineering", pages 253 to 277 (published on March 20, 1972), published by Shokusen Shoten. .

Examples of organic solvents used during disassembly include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohols such as methanol, ethanol, gropanol, and butanol; methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, Ester systems such as acetic acid glycol monoethyl ether; ether, glycol dimethyl ether, glycol monoethyl ether,
Glycol ethers such as dioxane; tars (aromatic hydrocarbons) such as benzene, toluene, and xylene; tetrachloride hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, and dichlorobenzene, etc. can be used.

By such a method, the magnetic layer coated on the support is optionally treated to orient the magnetic powder in the layer, and then the formed magnetic layer is dried.

The magnetic recording medium of the present invention is manufactured by subjecting the magnetic recording medium to a surface smoothing process, if necessary, and cutting it into a desired shape.

In this case, the orientation magnetic field is approximately 500 to 20
The drying temperature is about 50 to 100°C, and the drying time is about 3 to 10 minutes.

These are, for example, Japanese Patent Publications No. 39-28368, No. 40-
No. 23625, US Pat. No. 3,473,960, etc.

Furthermore, the method disclosed in Japanese Patent Publication No. 13181/1986 is considered to be a basic and important technique in this field.

The effects and advantages of the present invention are as follows.

(1) Coercive force can be increased by adjusting the sulfur content in the ferromagnetic metal particles.

(2) The di-saturation magnetization (σS) can be increased by adjusting the sulfur content in the ferromagnetic metal particles.

(3) Ferromagnetic metal particles with excellent dispersibility with a binder can be obtained.

(4) High Hc, high Bm, and high squareness ratio (
Br/Bm), a magnetic recording medium with excellent surface properties can be obtained.

(5) The amount of wear on the head due to contact with the head during recording and reproduction can be reduced.

The present invention will be explained in more detail below using examples.

It will be readily understood by those skilled in the art that the components, proportions, order of operations, etc. shown herein may be modified without departing from the spirit of the invention.

Therefore, the invention should not be limited to the examples below.

In addition, in the following examples, all parts indicate parts by weight.

Moreover, the M liquid and the R liquid are aqueous solutions. Example I M1 solution (ferrous chloride 0.685M/l R1 solution water Sodium borohydride 1.5M/l Add the above M11 parts to a stainless steel machine and apply a DC magnetic field of an average of 5000e while stirring gently. A reaction was carried out by adding 11 parts of R1 for 20 seconds, and five types of ferromagnetic powder (P-1 to P-
5) Obtained.

These powders were washed with water (using a 0.1 wt% aqueous solution of sodium oleate) without drying, and further replaced with acetone.

Acetone was further replaced with n-butyl acetate solution.

Table 1 below shows the amount of sodium hydrosulfide added to the M1 liquid and the sulfur content in the obtained metal powders (P-1 to P-5).

In FIG. 1, the saturation magnetic force (σs: emu/g) is shown by the curve ■.

In addition, other components of the metal powder (P-1) are Fe: 56, 4
wt, %, Co: 25.6 wt, %, Cr: 1. O
wt, %, 33: 3.1 wt, %.

Next, magnetic tapes were manufactured using the obtained powders pt, P-2, P-3, P-4 and P-5.

N-butyl acetate was added to 300 parts of the obtained powder so that the total amount of n-butyl acetate was 1200 parts, and the mixture was stirred at 40°C for 2 hours.

Thereafter, the following composition was added, and the mixture was placed in a ball mill and kneaded for 10 hours.

In addition to this, a polyisocyanate compound (Des-mo
dur L-75, manufactured by Bayer A, G) 3 moles of toluene diisocyanate and 1 mole of trimethyl, -
22 parts of a 75 wt% ethyl acetate solution of an adduct of lupropane was added, and high-speed tip dispersion was performed for 1 hour to obtain a magnetic paint.

This magnetic paint was applied to one side of a 25 micron thick polyethylene terephthalate film to a dry thickness of 5 µm while applying a magnetic field.
It was coated to a micron thickness and dried by heating.

The wide magnetic web thus obtained was supercalendered and slit into 1/2 inch widths to obtain video tapes.

The surface properties of the obtained tape were extremely good.

The obtained magnetic tapes were used as samples T-1, T-2, T-3, T
-4 and T-5.

In FIG. 1, the coercive force (He) is shown by curve I.

Figure 1 shows the relationship between the sulfur content and He of the videotape, and the relationship between σS of the ferromagnetic metal particles.

From this result, the sulfur content is 0.2 wt, 1 to 5.0
It was confirmed that those within the range of wt and % showed especially high values for both Hc and σS.

Furthermore, even in the reaction conducted without adding sodium idrosulfite, it was observed that 0.1 wt.% sulfur was contained.

On the other hand, powder containing 0.2 wt% sulfur and 1
Two types of powder containing 0wt% were heated at 60°C, 9
When the σS of the layer left for 5 days in a 0% atmosphere was measured, the σS of the powder containing sulfur of 0.2wt% was 90.4em.
u/g, but σS of powder containing 10 wt% sulfur
The amount was very small at 3.8 emu/g, and the color changed to yellow.

Furthermore, the amount of wear on the head was examined by running the videotape repeatedly while in contact with the ferrite head.
Compared to those using particles containing 0.1wt% sulfur,
Approximately 15% reduction was observed when using particles containing 2wt% sulfur.

Example 2 Ferromagnetic metal powder was obtained in the same manner as in Example 1 using liquid M2 and liquid R2.

Furthermore, a tape was made using the same recipe as in Example 1.

The analysis results of the obtained powder showed that iron was 57.1 wt%.
N cobalt is 26.0 wt.%, chromium is 1.0
wt, %, boron 3.2 wt, %, sulfur 1.
It was 7wt, chi.

Tape Hc is 11500e, squareness ratio is 0.82, Bm
is 3500 Gausss powder (7B is 116 emu
/g.

In addition, the particle size of the powder is an average minor axis of 250A and an average major axis of 1
It was 200A.

Although the present invention has the embodiments shown below, it is not limited thereto.

(Aspect 1): In Claim 1, the metal content of the ferromagnetic particles is 80 wt, and one or more of Fe and Co.

Ni, Fe-Co, Fe-Ni, Co-N
ferromagnetic metal particles that are Fe-Co7Ni or Fe-Co7Ni.

(Aspect 2): The ferromagnetic metal particles according to aspect (1), wherein the metal content of the ferromagnetic particles is 80 wt, 1 or more, and 50 wt, 1 or more of the metal is Fe.

(Aspect 3): 50 to 80% of the metal in (Aspect 1)
is Co, Ni or Co-Ni.

(Aspect 4): In (Aspect 1), the metal
19.8wt, % is Cr, P, B, Pb.

Sn w Zn, Ti, Mo, Mn, Ag
, Ferromagnetic metal particles comprising at least one element selected from the group consisting of Cu and Bi.

(Aspect 5): Ferromagnetic metal particles according to claim 1, having a particle size (minor axis direction) of 50 to 1000 angstroms.

[Brief explanation of drawings]

Figure 1 shows the relationship between the sulfur content and saturation magnetization (σs) (curve ■) of the ferromagnetic metal particles of the present invention, and the coercive force (He) I of the magnetic recording medium using the particles: curve I. This is a graph showing.

Claims (1)

Claims: 1. At least 75 wt.% of the ferromagnetic particles are metal, the metal component being at least 80 wt.% at least one selected from the group consisting of iron, cobalt and nickel.
In ferromagnetic metal particles containing a seed metal, the particles contain 0.2 to 5 wt of the metal component. Ferromagnetic metal particles characterized in that % is sulfur. 2. In a magnetic recording medium having a magnetic layer mainly composed of ferromagnetic metal particles and a binder, the ferromagnetic metal particles are at least 75 wt% of the ferromagnetic particles, and the metal component is at least 80 wt. Ferromagnetic metal particles containing at least one metal selected from the group consisting of iron, cobalt, and nickel, characterized in that the particles contain 0.2 to 5 wt.% of the metal component as sulfur. magnetic recording media.