JPS6118259B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved magnetic recording medium. Conventionally, ferromagnetic materials used for magnetic recording media such as audio tapes, video tapes, memory tapes, magnetic sheets, and magnetic cards include ferromagnetic iron oxide, cobalt ferrite, ferromagnetic chromium dioxide, or fine powder of ferromagnetic metals. There are ferromagnetic metal thin films, etc. The field of application of these magnetic recording media now covers an extremely wide range of technical fields such as recording and reproducing electrical or magnetic signals.
Recently, emphasis has been placed on methods for recording short-wavelength signals with high density. Along with this, ferromagnetic materials are required to have magnetic recording properties suitable for high-density recording, such as considerably high coercive force and high residual magnetic flux density. There is also a demand for magnetic cards that are less susceptible to demagnetization due to heating or pressurization. Metallic ferromagnetic materials are considered to be the most promising ferromagnetic materials that exhibit less demagnetization and are suitable for high-density recording. On the other hand, the recording wavelength for video tape is shorter than that for recording, and small home VTRs must record short wavelengths up to a minimum wavelength of about 2 microns. Particularly recently, VTRs that use a recording wavelength of about 0.6 to 1 .mu.m at the shortest wavelength have been developed. However, the above-mentioned oxide magnetic material has a short recording wavelength (approximately 2μ
(Below) It was not very suitable for magnetic recording of signals. That is, the particle size and other shapes and magnetic properties such as coercive force and residual magnetic flux density were insufficient for use in so-called high-density recording. Ferromagnetic metal powder is being actively developed as a material that satisfies these characteristics and enables high-density recording. Various methods are known for obtaining powdered metal magnetic materials. For example, the following six methods are generally known. [1] A method of reducing metal oxalates capable of producing ferromagnetic materials at high temperatures in a hydrogen stream [Special Publication No. 1973]
−11412, No. 36-22230, No. 38-14809,
No. 40-8027, No. 41-14818, No. 43-22394
No. 47-38417, etc.]. [2] Method for reducing goethite or acicular γ-Fe ₂ O ₃ in a high-temperature hydrogen stream [Special Publication No. 35-3862
No. 47-39477, U.S. Patent No.
No. 3607220, No. 3681018, No. 3598568,
See specifications such as British Patent No. 1192167]. [3] Method of vaporizing ferromagnetic metal in inert gas [Special Publication No. 47-27718, JP-A No. 48-25662~
48-25665, 48-55400, etc.]. [4] Method for decomposing metal carbonyl compounds that can produce ferromagnetic materials
Publications such as -3415, U.S. Patent No. 2983997,
Same No. 3172776, Same No. 3200007, Same No. 3228882
Please refer to each specification of the No. 1, etc.]. [5] A method in which a ferromagnetic metal is electrodeposited in mercury using a mercury cathode and then separated from the mercury by heating [Patent Publications No. 39-787, No. 39-15525, and No. 40-8123] , see US Pat. No. 3,156,650]. [6] A method of obtaining ferromagnetic powder by reducing a metal salt capable of forming a ferromagnetic substance using a reducing substance (borohydride compound, phosphinate, hydrazine, etc.) in an aqueous solution [Patent Publication No. 38-26555
No. 41-4567, No. 41-4769, No. 43-
Publications such as No. 20116, No. 47-16052, No. 47-41718, JP-A-47-1353, and No. 48-79754,
U.S. Patent No. 3206338, U.S. Patent No. 3700499, U.S. Patent No.
No. 3494760, No. 3535104, No. 3567525,
See specifications such as No. 3663318 and No. 3661556]. However, tapes made by kneading and dispersing the ferromagnetic powder obtained by these methods with binders, dispersants, etc. and coating them on a support have poor dispersibility, surface properties, and abrasion resistance, and are difficult to use for video tapes, etc. It has been extremely difficult to use it as a short wavelength recording tape. This is thought to be because the ferromagnetic metal powder is active and has properties that make it difficult to mix with the binder, such as being hydrophilic. In particular, ferromagnetic metal powder obtained by reduction with a phosphinate compound or a borohydride compound in an aqueous solution has poor compatibility with a binder, making it difficult to create a highly sensitive magnetic recording medium with good wear resistance. It was difficult.
Furthermore, when the obtained magnetic recording medium was exposed to high temperature and high humidity, the alloy fine powder was oxidized, resulting in a decrease in the magnetic flux density of the magnetic recording medium. As a result of repeated research in order to provide a high-density magnetic recording medium that improves the above-mentioned drawbacks, the present inventors have found that when a fine alloy powder is surface-treated with an organosilicon compound represented by the following general formula [], The inventors have discovered that remarkable effects can be achieved, leading to the present invention. That is, the present invention provides a magnetic recording material comprising a magnetic layer in which ferromagnetic powder is dispersed in a binder on a non-magnetic support, in which the ferromagnetic powder is an organosilicon compound represented by the following general formula []. This is a magnetic recording medium characterized by surface treatment. (However, in the general formula [], R, R',
R'' is a saturated hydrocarbon group or aromatic group having 1 to 6 carbon atoms, M is an alkali metal.) In the above general formula [], R, R' and
The number of carbon atoms in the saturated or unsaturated hydrocarbon group represented by R'' is preferably 1 to 6, and R,
R′ and R″ may be the same or different. If the number of carbon atoms is 7 or more, production is industrially difficult and steric hindrance deteriorates the reaction with the surface of the magnetic material, so it is not preferable. , R' and R'' are preferably an alkyl group such as methyl, ethyl, propyl, butyl, or a phenyl group. The alkali metal represented by M is lithium,
These include sodium, potassium, rubidium, and cesium, and particularly preferably sodium or potassium. The organosilicon compounds of the present invention can be used alone or in combination of two or more. The organosilicon compound represented by the above general formula [] contains 1 to 30% by weight of magnetic powder, preferably 3 to 15% by weight.
It is added to a water slurry containing 0.2 to 1.0% by weight, preferably 0.4 to 5% by weight, of a water slurry (which may also contain an inert organic solvent that is miscible with water). After addition, the slurry is stirred at 10-80°C for 3 minutes to 2 hours, preferably 15-35°C for 5 minutes to 30 minutes.
After stirring, remove excess water to form a cake with a moisture content of 50 to 80%, and then stir at 0.01 to 100 Torr and a temperature of 30 to 250℃.
24 hours, preferably 0.1-20Torr, 80-150℃
By drying for ~10 hours, the surface of the magnetic body and the organic silicone compound of the present invention are allowed to react. If the concentration of the organosilicon compound in the aqueous slurry of magnetic powder is less than 0.2% by weight, the dispersibility of the magnetic powder will not be improved; if it is more than 10% by weight, the concentration will be too excessive and will not only be uneconomical but also improve the dispersibility. is not often seen. If the pressure during drying is 100 Torr or more, the obtained alloy fine powder will be oxidized, which is not preferable. The temperature is
If it is below 30°C, the reaction between the organic silicon compound and the magnetic powder will be slow, which is undesirable, and if it is above 250°C, the magnetic powder will easily sinter, which is not preferable. The organosilicon compound used in the present invention can be obtained by reacting a trialkylmonochlorosilane obtained by reacting a Grignard reagent with tetrachlorosilane and an aqueous solution containing an alkali metal, or by reacting a halogenated carbon with silicon. It can be obtained by reacting a trialkylmonochlorosilane with an aqueous solution containing an alkali metal, or by reacting a trialkylsiloxane dimer with an aqueous solution containing an alkali metal. Specific examples of the above-mentioned organosilicon compounds include the following, and -1 is the most preferred because it is industrially easiest to obtain.

【formula】

【formula】

【formula】

【formula】

【formula】

An example of reacting methyl silicon acid (CH ₃ Si O _1.5 ) to silica, silicate, or _metal oxide as a compound similar to the above compound is shown in U.S. Pat. No. 2,886,460; Furthermore, there is no indication of processing metal ferromagnetic powders such as the liquid-phase reduced alloy powders shown in the present invention. Silane coupling agents (dispersants) such as alkyltriethoxyranes can be mentioned as organosilicon compounds similar to the compounds of the present invention, but these do not sufficiently exhibit the effects shown by the compounds of the present invention. Nakatsuta. This is thought to be due to the poor adsorption of the silane coupling agent to the surface of the magnetic material and the fact that the reaction is carried out by dealcoholization, but this is not a major cause. Regarding the manufacturing method of the magnetic paint used in the present invention, Japanese Patent Publications No. 35-15, No. 39-26794, No. 43-186, No. 47 of the same
-28043, 47-28045, 47-28046, 47-28045, 47-28046,
No. 47-28048, No. 47-31445, No. 48-11162,
It is described in detail in publications such as No. 48-21331, No. 48-33683, and Soviet Patent Specification No. 308033. 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℃ or less,
Average molecular weight is 10000~200000, degree of polymerization is about 200~
2000, such as 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 acid 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, polyamide resin, polyvinyl butyral, cellulose derivative (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate,
nitrocellulose, etc.), styrene-butadiene copolymers, polyester resins, chlorovinyl ether acrylate copolymers, amino resins, various synthetic rubber-based thermoplastic resins, and mixtures thereof. Examples of these resins are given in Japanese Patent Publication Nos. 37-6877 and 39.
−12528, No. 39-19282, No. 40-5349, No. 40
−20907, No. 41-9463, No. 41-14059, No. 41
−16985, No. 42-6428, No. 42-11621, No. 43
−4623, No. 43-15206, No. 44-2889, No. 44
−17947, No. 44-18232, No. 45-14020, No.
No. 45-14500, No. 47-18573, No. 47-22063,
No. 47-22064, No. 47-22068, No. 47-22069
No. 47-22070, No. 48-27886, U.S. Patent No. 3144352; No. 3419420; No. 3499789;
It is described in the specification of No. 3713887. The thermosetting resin or reactive resin has a molecular weight of 200,000 or less in the coating liquid state, but when added 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, examples include phenolic resins, epoxy resins, polyurethane curable resins, urea resins, melamine resins, alkyd resins, silicone resins, acrylic reaction resins, mixtures of high molecular weight polyester resins and isocyanate prepolymers, and methacrylate copolymers. and diisocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, low molecular weight glycols/
These include mixtures of high molecular weight diols/triphenylmethane triisocyanate, polyamine resins, and mixtures thereof. Examples of these resins are given in Japanese Patent Publication Nos. 39-8103 and 40.
-9779, 41-7192, 41-8016, 41-
No. 14275, No. 42-18179, No. 43-12081, No. 44
-28023, 45-14501, 45-24902, 45-24902,
No. 46-13103, No. 47-22065, No. 47-22066,
No. 47-22067, No. 47-22072, No. 47-22073
No. 47-28045, No. 47-28048, No. 47-
Publication No. 28922, US Patent No. 3144353; US Patent No. 3320090
No. 3437510; No. 3597273; No. 3781210;
It is described in the specification of No. 3781211. These binders may be used alone or in combination, and other additives may be added. The binding ratio of the ferromagnetic powder and the binder is 10 to 400 parts by weight of the binder to 100 parts by weight of the ferromagnetic powder, preferably 10 to 400 parts by weight.
Used in a range of 30 to 200 parts by weight. In addition to the above-mentioned binder and fine ferromagnetic powder, additives such as a dispersant, a lubricant, an abrasive, and an antistatic agent may be added to the magnetic recording layer. Dispersants include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid,
Fatty acids with 12 to 18 carbon atoms such as linolenic acid and stearolic acid (R ₁ COOH, R ₁ is an alkyl group with 11 to 17 carbon atoms); alkali metals (Li,
Na, K, etc.) or alkaline earth metals (Mg, Ca, etc.)
Metal soap consisting of Ba); lecithin, etc. are used. In addition, higher alcohols having 12 or more carbon atoms and sulfuric esters can also be used. These dispersants are added in an amount of 1 to 20 parts by weight per 100 parts by weight of the binder. Examples include Special Publication No. 39-28369 and No. 44-17945.
No. 48-15001, U.S. Patent No. 3387993;
It is described in the specification of No. 3470021, etc. Lubricants include silicone oil, carbon black, graphite, carbon black graft polymer, molybdenum disulfide, tungsten disulfide, monobasic fatty acids with 12 to 16 carbon atoms and 3 carbon atoms.
~Fatty acid esters consisting of 12 monohydric alcohols, monobasic fatty acids with 17 or more carbon atoms, and fatty acids consisting of monohydric alcohols with a total carbon number of 21 to 23 carbon atoms in the fatty acid. Ester etc. can be used. These lubricants are added in an amount of 0.2 to 20 parts by weight per 100 parts by weight of the binder. Regarding these, please refer to Japanese Patent Publication No. 43-23889 and Japanese Patent Application No. 42-2388.
28647, specifications of Japanese Patent Application No. 1983-81543, etc., U.S. Patent No. 3470021; U.S. Patent No. 3492235; U.S. Patent No. 3497411;
No. 3523086; No. 3625760; No. 3630772; No. 3630772;
No. 3634253; No. 3642539; Specification No. 3687725;
“IBM Technical Disclosure Bulletin” Vol.9,
No.7, Page 779 (December 1966);
Described in “ELEKTRONIK” 1961, No. 12, Page 380, etc. Commonly used abrasive materials include fused alumina, silicon carbide chromium oxide, corundum, artificial corundum, diamond, artificial diamond, garnet, and emery (main components: corundum and magnetite). These abrasives have an average particle size of 0.05 to 5μ,
Particularly preferably, it is 0.1 to 2μ. These abrasives are added in an amount of 7 to 20 parts by weight per 100 parts by weight of the binder. Regarding these, please apply for
No. 26749, US Patent No. 3007807; US Patent No. 3041196
No. 3293066; No. 3630910; No. 3687725;
British Patent No. 1145349; West German Patent (DT-PS)
It is described in the specification of No. 853211. Antistatic agents include conductive powders such as graphite, carbon black, and carbon black graft polymers; natural surfactants such as saponin;
Nonionic surfactants such as alkylene oxide, glycerin, and glycidol; cationic surfactants such as higher alkylamines, quaternary ammonium salts, pyridine and other heterocycles, phosphonium or sulfonium; carboxylic acids, sulfonic acids , anionic surfactants containing acidic groups such as phosphoric acid, sulfuric acid ester groups, and phosphoric ester groups; amphoteric surfactants such as amino acids, aminosulfonic acids, and sulfuric or phosphoric esters of amino alcohols. Some examples of surfactant compounds that can be used as antistatic agents are U.S. Pat.
No. 2288226, No. 2676122, No. 2676924,
Same No. 2676975, No. 2691566, No. 2727860, Same No.
No. 2730498, No. 2742379, No. 2739891, No.
No. 3068101, No. 3158484, No. 3201253, No. 3201253, No.
No. 3210191, No. 3294540, No. 3415649, No. 3210191, No. 3294540, No. 3415649, No.
No. 3441413, No. 3442654, No. 3475174, No. 3441413, No. 3442654, No. 3475174, No.
No. 3545974, West German Patent Publication (OLS) 1942665
British Patent No. 1077317, British Patent No. 1198450, etc., "Synthesis of Surfactants and Their Applications" by Ryohei Oda et al. (Maki Shoten 1964 edition); "Surf S Active Agents" by A.W. Peiri (Interscience Pub. Relocation Incorporated
1958 edition); TP Sisley, “Encyclopedia of Surf S Active Agents, Volume 2” (Chemical Publishing Company, 1964 edition); “Surfactant Handbook”, 6th edition (Sangyo Tosho Co., Ltd., 1966 (December 20), etc. These surfactants may be added alone or in combination. Although these are used as antistatic agents, they are sometimes applied for other purposes, such as dispersion, improving magnetic properties, improving lubricity, and as coating aids. To form the magnetic recording layer, the above-mentioned composition is dissolved in an organic solvent and applied as a coating solution onto a non-magnetic support. This support is made of polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, plastics such as polycarbonate, Cu, Al, and Zn.
Non-magnetic metals such as glass, ceramics such as porcelain and earthenware are used. The thickness of these non-magnetic supports is approximately 3 to 100 μm in the case of a film or sheet, preferably 5 to 100 μm.
50μm, and 0.5 for disks and cards.
The diameter is approximately 10 mm, and if it is drum-shaped, it is cylindrical, and its shape is determined depending on the recorder used. The above-mentioned support may be coated with a so-called backcoat on the side opposite to the side on which the magnetic layer is provided for the purpose of preventing static electricity, preventing transfer, and the like. Regarding back coats, for example, the US patent
No. 2804401, No. 3293066, No. 3617378, No.
No. 3062676, No. 3734772, No. 3476596, No.
No. 2643048, No. 2803556, No. 2887462, No.
No. 2923642, No. 2997451, No. 3007892, No.
It is shown in the specifications of No. 3041196, No. 3115420, No. 3166688, etc. In addition, the form of the support is tape, sheet, card,
It may be a disk, a drum, etc., and various materials are selected depending on the form as necessary. The magnetic powder and the above-mentioned binder, dispersant, lubricant, abrasive, antistatic agent, solvent, etc. are kneaded to form a magnetic paint. During kneading, the magnetic powder and each of the above-mentioned components are fed into a kneader either simultaneously or individually one after another. For example, there is a method in which magnetic powder is first added to a solvent containing a dispersant and kneaded for a predetermined period of time, and then the remaining components are added and kneading is continued to obtain a magnetic paint. Various kneaders are used for kneading and dispersing. For example, two-roll mill, three-roll mill, ball mill, pebble mill, thoron mill, sand grinder, Szegvari attritor, high-speed impeller disperser, high-speed stone mill, high-speed impact mill, disper, kneader, high-speed mixer, homogenizer, ultrasonic disperser, etc. It is. The technology related to kneading and dispersion is described in “Paint Flow and Pigment Dispersion” by TCPATTON (1964).
(published by John Wiley & Sons). It is also described in US Pat. No. 2,581,414 and US Pat. No. 2,855,156. Methods for coating the magnetic recording layer on the support include air doctor cord, blade coating,
Air knife coat, squeeze coat, impregnated coat, reverse roll coat, transfer roll coat, gravure coat, kiss coat, cast coat, spray coat, etc. can be used, and other methods are also possible. Specific explanations of these are published by Asakura Shoten. It is described in detail in ``Coating Engineering,'' pages 253 to 277 (published on March 20, 1972). Organic solvents used during coating include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohols such as methanol, ethanol, propanol, and butanol; methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and acetic acid. Ester systems such as glycol monoethyl ether; glycol ether systems such as ether, glycol dimethyl ether, glycol monoethyl ether, and dioxane; tar systems (aromatic hydrocarbons) such as benzene, toluene, and xylene; methylene chloride, ethylene chloride, and tetrachloride Carbon, chloroform, ethylene chlorohydrin, chlorinated hydrocarbons such as 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. Further, the magnetic recording body of the present invention is manufactured by subjecting it to surface smoothing processing and cutting it into a desired shape, if necessary. In this case, the orientation magnetic field is approximately 500 AC or DC
~10000 gauss or so, and the drying temperature is approximately 50~100 gauss
℃, and the drying time is about 3 to 10 minutes. Methods for orienting magnetic powder are also described in the following patents: For example, US Patent No. 1949840; US Patent No. 2796359;
No. 3001891; No. 3172776; No. 3416949; No. 3172776; No. 3416949;
No. 3473960; Specification No. 3681138; Special Publication No. 32-3427
No. 39-28368; No. 40-23624; No. 40-
No. 23625; No. 41-13181; No. 48-13043; No. 48
-39722 publication, etc. The orientation direction of the magnetic material is determined by its use. i.e. sound tape, small video tape,
In the case of memory tapes, it is oriented parallel to the length of the tape, and in the case of broadcast video tapes, it is oriented at an angle of 30° to 90° with respect to the length. The present invention will be explained in more detail below using examples. Those skilled in the art will readily understand 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. Example 1 Ferrous sulfate in a DC magnetic field of 1000 oersted
A fine alloy powder was obtained by adding 1 mole of sodium borohydride to an aqueous solution containing 0.685 mole/cobalt sulfate, 0.305 mole/cobalt sulfate, and 0.010 mole/chromium alum. The obtained alloy powder has a shape in which 10 to 15 particles with a diameter of 400 Å are chained on average, and has a composition of Fe:Co:cr≒69:30:1 and also contains about 3% B. Was. Add 300 parts of the obtained alloy fine powder to 2700 parts of water, add this compound-1 while stirring with an impeller (the amount used is shown in Table 1), stir at 25°C for 15 minutes, and then dehydrate with a centrifuge. A cake containing about 30% alloy fine powder was made. This cake was dried at a temperature of 110° C. in a vacuum of 90 Torr for 2 hours and in a vacuum of 10 Torr for 3 hours to cause the surface of the alloy fine powder to react with the organosilicon compound. then

[Table] The above composition was placed in a ball mill, kneaded and dispersed for 24 hours, and 28 parts of a polyisocyanate compound (Desmodur L-75, manufactured by Bayer AG, consisting of 1 mol of trimethylolpropane and 3 mol of tolylene diisocyanate) was added. After adding a 75% by weight solution of the adduct in ethyl acetate), high-speed shear dispersion was performed for 2 hours. After the above treatment, it was filtered through a filter having an average pore size of 3μ to obtain a magnetic paint. The obtained magnetic paint was coated with a doctor coat onto a polyethylene terephthalate film having a thickness of 22 μm to a dry thickness of 6 μm. This is 2500
After performing magnetic field orientation for 0.02 seconds using an Oersted DC magnetic field and drying for 2 minutes at 100℃ and 3Kg/ ^m2 air flow, supercalender at 60℃ and a pressure of 60Kg/cm at a speed of 40m/min. Perform roll processing,
A wide magnetic recording film was obtained. This was slit to obtain a 1/2 inch wide videotape. Table 1 shows the amount of the organic silicon compound used and the measurement results of the magnetic material and magnetic recording material obtained.

[Table] A magnetic recording medium was obtained in the same manner as in Example 1 except that Compounds -2 and -3 were used in place of the organosilicon compound used in Example 1. Table 2 shows the type and amount of the organosilicon compound used and the measurement results.

[Table] Comparative Example A magnetic recording medium was prepared in the same manner as in Example 1, using a silane coupling agent CH ₂ =CHSi(OC ₂ H ₅ ) ₃ instead of the organic silicon compound used in Example 1. Obtained. The results obtained are shown in Table 3.

[Table] The method for measuring the characteristic values shown in each table is shown below. a Saturation magnetization: The obtained alloy fine powder is exposed to an external magnetic field.
Measured at 5000Oe. Measuring instrument: Manufactured by Toei Kogyo KK
VSM-3. b Maximum magnetic flux density: Measured with an external magnetic field of 3000 Oe in the orientation direction of the obtained magnetic recording body. Measuring instrument:
VSM-3. c Squareness ratio: Ratio between residual magnetic flux density (Br) and saturation magnetic flux density (Bm) when measured with an external magnetic field of 3000 Oe in the orientation direction of the obtained magnetic recording body. Measuring instrument: VSM-3. d 5MH _Z output: Playback output when a 5MH _Z reference signal is recorded at the optimum recording current using a standard VTR. The relative value recording wavelength on the magnetic recording medium is 2.2 μ with respect to the CrO ₂ tape. Measuring instrument:
AV-8700 manufactured by SONY Corp. e Durability: Value measured as the time (minutes) until an abnormality appears on the monitor TV screen when a test pattern is recorded and played back in still mode. Measuring instrument: AV-8700. From Tables 1 and 2 above, when the surface treatment of the alloy fine powder is performed using the organosilicon compound according to the present invention, the dispersing agent of the alloy fine powder becomes better, and therefore the maximum magnetic flux density of the obtained magnetic recording medium is It will be seen that the squareness ratio is particularly large, the output when recording at a short wavelength of _5MHZ is improved, and the durability is also improved. From Table 3, it can be seen that although the silane coupling agent is better than not using it, it does not show as much improvement in properties as the organosilicon compound according to the present invention, especially in the squareness ratio 5MH _Z output. From the above, it will be understood how effective the organosilicon compound according to the present invention is in improving the dispersibility of fine alloy powder.

Claims (1)

[Claims] 1. A magnetic recording material comprising a magnetic layer in which ferromagnetic powder is dispersed in a binder on a non-magnetic support, wherein the ferromagnetic powder is an organic compound represented by the following general formula []. A magnetic recording body characterized by being surface-treated with a silicon compound; [However, in the above general formula [], R, R',
R″ is a saturated hydrocarbon group or aromatic group having 1 to 6 carbon atoms, and M is an alkali metal.] 2 In the organosilicon compound represented by the general formula [], R is CH ₃ and M is selected from Na and K. 3. The magnetic recording medium according to claim 1, characterized in that the ferromagnetic powder is a liquid-phase reduced alloy fine powder. 4. The magnetic recording body according to claim 3, wherein the surface treatment is performed in a vacuum state of 100 Torr or less.