JPS6028050B2 - magnetic recording medium - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a magnetic recording medium, and in particular to a magnetic coating liquid having excellent dispersibility, and a high-density magnetic recording medium having excellent surface storage stability and high reproduction output. Conventionally, in magnetic recording media such as video tapes, y
-Fe203, Co containing y-Fe2Q, Fe304, C
The powder of metal oxides such as Fe2Q and C containing ferromagnetic substances was dispersed in a binder using bran, coated on a non-magnetic flexible support, and dried. . The recording wavelength for these video tapes is about 2 French for small VTRs, but recently it has become necessary to use even shorter recording wavelengths in order to increase the recording density. However, in magnetic recording media using metal oxides, saturation magnetic flux density (Bs) and coercive force (Hc)
Because of the low wavelength, it was not possible to obtain high reproduction output when the recording wavelength became short. Therefore, using metal ferromagnetic powder, B
Development of methods for obtaining magnetic recording bodies with large m and Hc is underway. The following methods have been proposed for producing metal ferromagnetic powder.

[1' Method of reducing oxalates of metals capable of producing ferromagnets at high temperatures in a hydrogen stream [Kiaki Hakama 3
No. 6-11412, No. 36-22230, Shigeru-1480
No. 9, No. 40-8027, No. 41-14818, No. 43-22394, No. 47-417, etc.]. [2] Method for reducing goethite or acicular y-Fe2Q in a high-temperature hydrogen stream [Special Publication Publication No. 62, No. 35 of 1973]
9-2093y, 47-3-77, etc., and specifications such as U.S. Patent No. 3598568, No. 3607220, No. 3681018, British Patent No. 1192167, West German Patent Publication No. 2130921] . (3) Method of evaporating ferromagnetic metal in inert gas [
Special Publication No. 46-2562 Pi No. 47-27718 and Special Publication No. 48-125662-25665, 48-554
See issue 00]. [4- Method for decomposing metal carbonyl compounds that can create ferromagnetic materials [Special Publication No. 38-12
No. 8, Publication No. 40-3415, U.S. Patent No. 298399
No. 7, No. 3172776, No. 3200007, 3228
882 specification]. ■ A method in which a ferromagnetic metal is lightning-deposited in mercury using a mercury cathode, and then heated to separate it from the mercury.
No. 39-15525, No. 40-8123, and US Pat. No. 315,665]. [6
} A method of obtaining ferromagnetic powder by reducing with a reducing substance (borohydride compound, hypophosphite, hydrazine, etc.) in an aqueous solution of a salt of a metal capable of forming a ferromagnetic substance [Japanese Patent Publication No. 38-26555 No. 41-4567, 41-4
No. 769, No. 43-20116, No. 47-16052,
47-41718, Tokukan Sho 47-11353, and 47-41718, U.S. Patent No. 3206338,
No. 3494760, No. 3535104, 3567525
No. 3661556, 3663318, 37004
9y specification]. Among the above methods, the alloy fine powder obtained by the evaporation method of '3} has a particle size of about 20
A fine powder having a shape in which several or more fine particles of 0 A are connected, and having magnetic properties with a coercive force of 60 e or more and a maximum magnetization ratio of 10 mu/multiple or more can be easily obtained. However, the obtained evaporation method alloy powder was extremely active as it was, and when it was taken out into the atmosphere, it eventually ignited and turned into an oxide with extremely poor magnetic properties. For this reason, until it is mixed with a binder or solvent to produce magnetic paint, it must be handled in a vacuum or in an inert gas atmosphere, which poses great difficulties. In addition, the dispersibility of the obtained magnetic paint is poor, and the magnetic recording material obtained by coating and drying it on a non-magnetic support has a reduced saturation magnetic flux density due to oxidation of the magnetic material under high temperature conditions. The storage stability was poor due to the phenomenon of storage. For this reason, a method has been proposed in which the surface of the alloy is oxidized to make it inactive. Surface oxidation stabilization treatment involves soaking the produced alloy powder in an organic solvent and then drying the organic solvent in the air to oxidize the surface layer. A method is known in which the surface is oxidized by slowly adding air after drying an organic solvent in an active gas, and these methods are described in U.S. Pat.
This is shown in the specification of No. 318, etc. However, when these methods were applied to the evaporation method, the resulting magnetic paint had poor dispersibility, and the storage stability of the magnetic recording medium obtained by coating and drying it on a non-magnetic support was also insufficient. Ta. The present inventors have studied a method for obtaining a magnetic coating material with good dispersibility by extracting evaporation alloy powder in a stable state into the atmosphere, and obtaining a magnetic recording medium with storage stability and high output. As a result, the present invention was achieved by discovering that it is sufficient to subject the evaporation method alloy powder to surface oxidation stabilization treatment and to add a certain type of phosphate ester to the magnetic layer. 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 evaporation alloy powder subjected to surface oxidation stabilization treatment. and the magnetic layer contains at least one kind of phosphate ester represented by the following general formulas 1 and 2 in an amount of 0.3 to 5% by weight based on the alloy powder. . (1, m, n are integers from 0 to 10, R, R
', R'' are saturated or unsaturated hydrocarbon groups having 6 to 22 carbon atoms.) The evaporation method alloy fine powder used in the present invention refers to the evaporation method alloy powder used in the present invention. An alloy or an alloy of a magnetic metal and a non-magnetic metal is heated and evaporated and then condensed.The inert gas used in the present invention is a non-oxidizing gas such as helium, nitrogen, argon, or neon. A small amount of oxygen may be included in these inert gases.The pressure of these inert gases is 0.05 to 30 mHg, preferably 0.
．． Suitable temperature range is 1 to 5 degrees Hg and -2000 to 60 qo, preferably 0 to 30 degrees Celsius. The magnetic metals used in the present invention include iron, cobalt, nickel, cadrinium, terbium, dysprosium, etc., and preferably iron,
Cobalt and nickel. These magnetic metals account for at least 8% by weight of the metals in the alloy, preferably at least 95% by weight. Nonmagnetic metals used in the present invention include zinc, aluminum, copper, tin, manganese, chromium, molybdenum, and the like. These amounts are less than 2% by weight of the metal content in the alloy, preferably less than 5% by weight. As a heat source for heating evaporation,
Plasma jets, electron beams or high frequency melting furnaces are effective. Among these, a plasma jet is preferable because it is easy to attach and arrange to the evaporation device, and the size of the entire device can be reduced. 1 when condensing metal vapor
Since 0 is higher than 0, and preferably 50K, applying a magnetic field of 500K will connect the fine particles to each other and increase the magnetic field orientation, which is preferable. The surface oxidation stabilization treatment suitable for the present invention means that the evaporation method alloy powder produced in an inert gas has a bulk specific gravity of 1.0 or less, preferably 0.5 or less, and air is poured into the evaporator on the 10 side. Hg/min or less, preferably 5 side Hg/min
The pressure inside the device is returned to atmospheric pressure by flowing at a rate of less than 1 minute, and a very thin oxide layer is formed on the surface of the alloy. The temperature at this time is -20 o'clock to 60 degrees Celsius, preferably 0 to 3
It is 0°C. When the bulk specific gravity is 1.0 or more, the surface oxidation stabilization treatment is not performed uniformly, and the saturation magnetization of the obtained evaporation method alloy powder becomes small. When the air inflow rate is 10 Hg/min or more, the alloy powder is oxidized and the saturation magnetization becomes small. The phosphate ester used in the present invention is a single phosphate ester or a mixture of phosphate esters represented by the following general formulas 1 and 0. 1, m, and n are integers from 0 to 10, and when they are 10 or more, the hydrophilicity increases, which is not preferable because storage stability deteriorates. R, R', and R'' are saturated or unsaturated hydrocarbon groups having 6 to 22 carbon atoms, particularly preferably 12 to 18 carbon atoms.
If the number of carbon atoms is less than 6, the storage stability of the obtained magnetic recording medium will be poor, and if it exceeds 22, it will not only be difficult to obtain industrially but also tend to cause blooming. The amount of phosphate ester added is 0.3 to 5% by weight, preferably 0.5% by weight based on the alloy powder.
~3% by weight. If the content is less than 0.3% by weight, the dispersibility of the alloy powder will not be improved, and if it exceeds 5% by weight, blooming will occur in the magnetic recording medium, which is not preferable. When the above compounds 1 and 0 are mixed and used, the mixing ratio of both (1:2) is arbitrary, but in particular about 2:8, no
A ratio of about 8:2 is preferred. Examples of phosphate esters used in the present invention are as follows. Compound 1-1 Compound 1-2 Compound 1-3 Compound 1-4 Compound 1-5 Compound 1-6 Compound 1-7 Compound 1-8 Compound 1-9 Compound 1-10 Compound 1-11 Compound Rho 1 Compound Rho 2 Compound Rho 3 FIG. 1 shows the relationship between the air inflow velocity during the surface oxidation stabilization treatment according to the present invention and the saturation magnetization of the obtained alloy powder. It can be seen that the inflow rate is preferably 10 skin Hg/min or less. FIG. 2 shows the relationship between the amount of phosphate ester added and the reproduction output of the obtained magnetic recording medium according to the present invention. It can be seen that the addition amount is preferably 0.3% or more. By performing the surface oxidation stabilization treatment according to the present invention and using a phosphate ester surfactant during dispersion, a magnetic coating material with excellent dispersibility that could not be obtained with conventional evaporation method alloys was obtained. Therefore, it was possible to obtain a magnetic recording medium with good surface properties and high reproduction output. It was found that the obtained magnetic recording material showed a small decrease in saturation magnetic flux density even under high temperature conditions and had good storage stability. 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 15,000 or less, the average molecular weight is 10,000 to 200,000, and the degree of polymerization is about 200 to 200.
2,000 or so, such as vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride copolymer, vinyl chloride acrylonilyl copolymer, acrylic acid ester acrylonitrile copolymer, acrylic acid ester vinylidene chloride copolymer, Acrylic acid ester styrene copolymer, methacrylic acid ester styrene copolymer, methacrylic acid ester vinylidene chloride copolymer, methacrylic acid ester styrene copolymer, urethane nystomer, polyvinyl fluoride, vinylidene chloride acrylonitrile copolymer Polymers, butadiene acrylonitrile copolymers, polyamide resins, polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), styrene butadiene copolymers, polyester resins , amino resins, various synthetic rubber-based thermoplastic resins (polybutadiene, polychloroprene, polyisoprene, styrene-butadiene copolymers, etc.)
and mixtures thereof are used. Examples of these resins are given in Japanese Patent Publication No. 37-16877, 39-
No. 12528, No. 39-19282, No. 40-534y, No. 40-20907, No. 41-9463, No. 41-14
No. 05, No. 41-16985, No. 42-6428, 4
No. 2-11621, No. 43-4623, 43-1520
No. 6, No. 44-288, No. 44-17947, No. 44-18232, No. 45-1402, No. 45-14500
No. 47-18573, No. 47-22063, No. 47-22064, No. 47-220, No. 47-22069, No. 47-2207, No. 48-27886, U.S. Patent No. 3144352; No. 3419420; 349
No. 9789; described in the specification of No. 3713887. The thermosetting resin or reactive resin has a molecular weight of 200,000 or less in the state of a coating solution, 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, for example, phenol/formalin/
Borac resin, phenol/formalin-resole resin, phenol/furfural resin, xylene/formaldehyde resin, urea resin, melamine resin, drying oil-modified alkyd resin, carbonic acid resin-modified alkyd resin, maleic acid resin-modified alkyd resin, unsaturated polyester Resins, Epoxy resins and curing agents (polyamines, acid anhydrides, polyamide resins, etc.), Terminal isocyanate polyester moisture-curing resins, terminal isocyanate polyether moisture-curing resins, polyisocyanate prepolymers (disocyanate Compounds having 3 or more isocyanate groups in one molecule, diisocyanate trimers and tetramers obtained by reacting and low molecular weight triols, polyisocyanate prepolymers and resins containing active hydrogen (
These include polyester polyols, polyether polyols, acrylic acid copolymers, maleic acid copolymers, 2-hydroxyethyl methacrylate copolymers, parahydroxystyrene copolymers, etc.), and mixtures thereof. Examples of these resins are given in Japanese Patent Publication No. 391-8103, 40
-9779, 41-7192, 41-8016,
41-14275, 42-1817, 43-12
No. 081, No. 44-28023, No. 45-14501,
46-24902, 46-13103, 47-22
No. 065, No. 47-22066, No. 47-22067,
No. 47-22072, No. 47-22073, No. 47-28
No. 045, No. 47-28048, No. 47-28922, US Pat. No. 3,144,353; US Pat. No. 3,320,090;
No. 3437510: No. 3597273: No. 3781
No. 21; described in the specification of No. 3781211. 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 10 parts by weight of the ferromagnetic powder to 1 part by weight of the binder.
It is used in a range of 0 to 4 parts by weight, preferably 10 to 25 parts by weight, more preferably 15 to 2 parts by weight. In addition to the above-mentioned binder and fine ferromagnetic powder, additives such as a dispersant, a lubricant, an abrasive, an antistatic agent, etc. may be added to the magnetic recording layer. Dispersants include caprylic acid, capric acid, lauric acid,
Fatty acids with 12 to 18 carbon atoms such as myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, stearolic acid (R, COO, R, is a fatty acid with 11 to 17 carbon atoms) alkyl or alkenyl group); alkali metals (Li, Na, K
) or alkali metals (Mg, Ca, Ba); fluorine-containing compounds of the above fatty acid esters; amides of the above fatty acids; lecithin; trialkylpolyolefin oxyquaternary ammonium salts (alkyl is carbon (1 to 5 olefins, olefins such as ethylene, propylene, etc.) are used. In addition, higher alcohols having 1 or more carbon atoms and sulfuric acid esters can also be used. These dispersants are added in an amount of 0.5 to 2 parts by weight based on 10 parts by weight of the binder. Regarding these, special public relations
836 number, 44-17945, 48-7441
No. 48-15001, No. 48-15002, No. 48-16363, No. 50-4121, U.S. Pat. No. 3, No. 7993; No. 3470021, etc. As lubricants, conductive fine powders such as carbon black, graphite, and carbon black graft polymers; inorganic fine powders such as molybdenum disulfide and tungsten disulfide; polyethylene, polypropylene, polyethylene vinyl chloride copolymers, polytetrafluoroethylene, etc. fine plastic powder; Q-olefin polymer; unsaturated aliphatic hydrocarbon that is liquid at room temperature (a compound in which an n-olefin double bond is bonded to the terminal carbon, approximately 20 carbon atoms); Fatty acid esters consisting of a monobasic fatty acid and a monohydric alcohol having 3 to 12 carbon atoms can be used. These lubricants are used in an amount of 0.2 to 10 parts by weight of the binder 10.
It is added in an amount of 2 parts by weight. Regarding these, please refer to Special Publication No. 41-18064, No. 43-2388y, No. 46-4
No. 0461, No. 47-15621, No. 47-1848
No. 2, No. 47-28043, No. 47-32001,
Publication No. 50-5042, US Pat. No. 3,470,021;
No. 3492235; No. 3497411; No. 3523
No. 086; No. 3625760; No. 3630772;
Specification No. 3642539; “IBM Technica
】Disclosure B mountainletin''Vol.
9, No. 7, Pa bag 779 (December 1966);
ELEKTRONIK” 1961, No. 12, Pa
This is described near ge38. 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 a Mohs hardness of 5 or more and an average particle diameter of 0.05 to 5 mm, particularly preferably 0.1 to 2 mm. These abrasives are added in an amount of 0.5 to 2 parts by weight per 100 parts by weight of the binder. Regarding these, Special Publication No. 47-18572, No. 48-15003
No. 48-15004 (U.S. Pat. No. 3,617,378), No. 49-39402, No. 50-9401,
U.S. Patent No. 3007807: U.S. Patent No. 3041196: U.S. Patent No. 3
No. 293066: No. 363091; No. 368772
No. 5: British Patent 114534 No.: West German Patent (DT
- PS) No. 853211: Described in the specification of PS No. 1101000. Antistatic agents include conductive fine powders such as carbon black, graphite, and carbon black graft polymers; natural surfactants such as saponin; nonionic surfactants such as alkylene oxides, glycerin, and glycidol; higher alkyls; Cationic surfactants such as amines, quaternary ammonium salts, pyridine and other heterocycles, phosphoniums or sulfoniums; carboxylic acids, sulfonic acids, phosphoric acids, sulfate ester groups,
Anionic surfactants containing acidic groups such as phosphoric acid ester groups:
Ampholytic activators such as amino acids, aminosulfonic acids, sulfuric acid or phosphoric acid esters of amino alcohols, etc. are used. The above conductive fine powder is 0.0% per 100 parts by weight of the binder.
2 to 20 parts by weight are added, while surfactants are added in the range of 0.1 to 1 part by weight. Some examples of conductive fine powders and surfactant compounds that can be used as antistatic agents include Japanese Patent Publications Nos. 46-22726, 47-24881, 47-26882, and 4
No. 8-15440, US Pat. No. 48-26761, US Pat. No. 2271623, US Pat. No. 2240472, US Pat. No. 2288
No. 226, No. 2676122, No. 2676924,
No. 2676975, No. 2691566, No. 2727
No. 860, No. 2730498, No. 2742379,
No. 2739891, No. 3068101, No. 3158
No. 484, No. 3201253, No. 3210191,
No. 3294540, No. 3415649, No. 3441
No. 413, No. 3442654, No. 3475174,
No. 3545974, West German Patent Publication (OLS) 19
42665, British Patent No. 1077317, British Patent No. 1198
Including the specification of 45 bibliography, etc., "Synthesis of surfactants and their applications" by Ryohei Oda et al. (Enoki Shoten 196 French edition); A. M.
Schwall & J. W. “Surf S Active Agents” by IJ Bay (Interscience Publications, Inc. 19th edition); J. P. "Encyclopedia of Surf S Active Agents, Volume 2" (Chemical Publishing Company - 1964 edition) by Sisley: "Surfactant Handbook" No. 6
It is written in books such as Print (Sangyo Tosho Co., Ltd., December 20, 1960). These surfactants may be added alone or in combination. These are used as antistatic agents, but are sometimes used for other purposes, such as dispersion, improving magnetic properties,
It may also be used to improve lubricity and as a coating aid.
The magnetic recording layer of the present invention is formed by dissolving the above-mentioned composition in an organic solvent, kneading and dispersing, and coating each coating solution on a non-magnetic support and drying. After coating this magnetic layer and before drying, a treatment can be performed to orient the magnetic powder in each magnetic layer.
Further, the surface of each magnetic layer can be smoothed after drying. Materials for this non-magnetic support include 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, AI, Non-magnetic metals such as Zn; ceramics such as glass, porcelain, and earthenware are used. In addition, the form of the non-magnetic support is film, tape, sheet,
It may be a disk, card, drum, etc., and various materials are selected depending on the form as necessary. The thickness of these non-magnetic supports is approximately 2 to 50 mm in the case of films, tapes, and sheets, preferably 3 to 25 mm.
It is of the Buddha. Further, in the case of a disk or card shape, the length is about 0.5 to 1 m², and in the case of a drum shape, it is cylindrical, and the shape is determined depending on the recorder used. In the case of flexible supports such as films, tapes, sheets, and thin flexible disks, the non-magnetic supports mentioned above are coated with a magnetic layer for the purpose of preventing static electricity, preventing transfer, and preventing wow and flutter. The opposite side to the provided side may be so-called back coated (ie, have a back layer). Regarding the back coat, for example, US Patent No. 280,440
No. 1, No. 3293066, No. 3617378, No. 3
No. 062676, No. 3734772, No. 347659
No. 6, No. 2643048, No. 2803556, No. 2
No. 887462, No. 2923642, No. 299745
No. 1, No. 3007892, No. 3041196, No. 3
No. 115420, No. 3166688, No. 376131
This is shown in the Specification No. 1, etc. magnetic powder and the aforementioned binders, dispersants, lubricants, abrasives,
The antistatic agent, solvent, etc. are kneaded to form a magnetic paint. During the moat kneading, the magnetic powder and each of the above-mentioned components are fed into a kneading machine 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 to obtain a magnetic paint.
Various types of thickeners are used to disperse the magnetic coating liquid in the rice bran. For example, two roll mill, three roll mill, ball mill,
These include vebble mill, thoron mill, sand glider, Sze bait an attritor, high speed inveter disperser, high speed stone mill, high speed impact mill, disper, kneader, high speed mixer, homogenizer, ultrasonic disperser, etc.
The technique for dispersing lacrimal fluid is described by T. C. Written by PATTON “
PaintFlowandPigmentDisper
sion” (1964, John Wiley & S.
published by ons). 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 coating, plaid coating, air knife coating, squeeze coating, impregnation coating, and reverse coating. Roll coat, transfer roll coat, gravure coat, kiss coat, cast coat, soubray coat, etc. can be used, and other methods are also possible. Specific explanations of these methods can be found in "Coating Engineering" published by Asakura Shoten, pages 253 to 277 (Showa 46.3.2 Assurance). In the magnetic recording material of the present invention, a magnetic layer is coated on a nonmagnetic support by the coating method described above and dried. Alternatively, two or more magnetic layers may be provided by repeating this step and performing continuous coating operations. Also, Tokuseki Sho 48-198803
No. [West German Published Patent (DT-OS) No. 230915y], No. 48-99233 [West German Published Patent (DT-OS) No. 2309158] As described in the publications, etc., two or two layers can be coated simultaneously by a multilayer simultaneous coating method. The above magnetic layers may be provided. Organic solvents used during coating include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; methanol,
Alcohols such as ethanol, propanol, butanol; Esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, acetic acid glycol monoethyl ether:
Glycol ethers such as ether, glycol dimethyl ether, glycolmo/ethyl ether, and dioxane; Tars (aromatic hydrocarbons) such as benzene, toluene, and xylene; methylene chloride, ethylene chloride, carbon tetrachloride, chloroform , chlorinated hydrocarbons such as ethylene chlorohydriso, 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 as described above, 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 particular, in the present invention, it has been found that by subjecting the magnetic recording layer to surface smoothing treatment, a magnetic recording body with a smooth surface and excellent wear resistance can be obtained. In this case, the orientation magnetic field is about 500 to 10,000 Gauss in alternating current or direct current. The drying temperature of the magnetic layer is approximately 50 to 1500C, preferably 70 to 120Q, particularly preferably 80 to 100,000C.
The air flow rate is 1 to 5 M/force, preferably 2 to 3 W/me, and the drying time is about 3 to 10 minutes, preferably 1 to 3 W/force.
It's 5 minutes. The orientation direction of the magnetic material is determined by its use. That is, in the case of sound tape, small video tape, memory tape, etc., it is parallel to the length direction of the tape, and in the case of broadcast video tape, etc., it is parallel to the length direction.
It is oriented with a slope of 00 to 900. The orientation direction of magnetic powder is also described in the following patents: For example, US Patent No. 1949840:2796359:
No. 3001891; No. 3172776; 341694y
No.: 347396; Specification No. 3681138; Special Publication No. 32-3427: 39-283 Congee No. 40-236
No. 24; No. 40-23625; No. 41-13181; 4
No. 8-13043: No. 48-39722, etc. Also, as described in German Patent Application No. DT-AS 1190985, the upper and lower layers may be oriented in different directions. The surface smoothing treatment after drying of each of the magnetic layers described above is carried out by calendering, smoothing sheet, or the like. In the case of calendering, it is preferable to carry out the supercalendering method in which the material is passed between two rolls such as a metal roll and a cotton roll or a synthetic resin (for example, nylon) roll. The conditions of the supercalender are an inter-roll pressure of about 50 to 1000 k9/kg, preferably 100 to 500 kg/kg, a temperature of about 35 to 150°C, preferably 40 to 1000°C, and a processing speed of 5 to 150 skins/min. It is preferable to do so. Temperature and pressure above these upper limits have an adverse effect on the magnetic layer and non-magnetic support. Also, the processing speed is about 5
If it is less than about 500 m/min, industrial productivity will be poor, and if it is more than about 500 m/min, processing operations will become difficult. Regarding these surface smoothing treatments, see US Patent Nos. 2,688,567; 2,998,325.
No. 3783023; West German published patent (DT-OS)
Specification No. 2405222; JP-A-49-53631;
It is described in Publication No. 50-10337. The present invention will be explained below using examples. The evaporation method alloys used in Examples A to E and Comparative Examples A to D were obtained as follows. An alloy with a weight ratio of Fe:Ni = 80:20 was placed in a sealed container equipped with a plasma gun, an air-core coil, and a conical collector, and the container was heated to 0.5 Hg and 20 kg with argon gas. After that, it is heated with an argon gas plasma jet and evaporated. When the evaporated metal vapor was condensed, a magnetic field of 50 e was applied using an air-core coil, and then collected using a collector. After compiling,
2,500 ml of air was introduced into the airtight container at the inflow rate shown in Table 1, and the air was taken out into the atmosphere, and the saturation magnetization was measured. The results are shown in Table 1 and FIG. Further, Table 2 shows the saturation magnetization when the bulk specific gravity of the evaporation method alloy was changed when surface oxidation stabilization treatment was performed. Table 1 * Not measured because some part was burned Table 2 Examples 1 to 22 and Comparative Examples 1 to 12 Using the evaporation method alloy powder of Example B, magnetic paint and magnetic recording material were obtained by the method shown below. Ta. Evaporation method alloy powder 30% polyester polyurethane (synthesized mainly from ethylene adipate 4,4-diphenylmethane diisocyanate, styrene equivalent weight average molecular weight 130,000), 2-prong synthetic non-drying oil-modified alkyd resin (mainly glycerin, anhydrous) Phthalic acid, synthesized from synthetic non-drying oil, oil length 29%, hydroxyl value approximately 130) 25 parts silicone oil (dimethylborisiloxane) 2 parts phosphate ester (types and amounts added are shown in Tables 3 to 9)
2-part butyl acetate
Put the above composition into a pole mill 2
After 4 hours of dispersion treatment, polyisocyanate (Bayer A
Two parts of Desmodur L-75) manufactured by Company G were added and high speed periodic dispersion was performed for 1 hour to obtain a magnetic paint. The obtained magnetic paints had average pore diameters of 10 mm, 5 mm, and 3 mm, respectively.
The dispersibility of the magnetic paint was examined by filtering it through a filter having a diameter of 1. The results are shown in Tables 3 and 4. Of the magnetic paints obtained, the one filtered through a filter having the smallest average pore diameter was applied onto a polyethylene terephthalate film having a thickness of 22 mm to a dry thickness of 3 mm. Next, a magnetic field orientation treatment was performed using a DC magnetic field of 2500 Gauss for 0.02 stages, and after drying at 120°C for 2 minutes, a super calendar roll treatment was performed, and the tape was slit into 1/2-inch pieces to obtain a videotape. Ta. The results obtained are shown in Tables 3-8. Table 3 Comparative tests were conducted using the following phosphate esters, which are different from the phosphate esters of the present invention. Compound 1'-12 Compound 1'-13 Compound 1'-14 Compound 1'-15 Compound D'-4 Compound 0'-5 Table 4 Examples of those with too few and too many carbon atoms in R, R, and R4 Note) C numbers in the above table indicate comparative examples; the same applies below) Table 5 Table of examples with different degrees of polymerization of okinethylenic acid 6 Table of differences depending on the amount of phosphate ester added 7 Examples with different R and R' followed by monophosphoric acid Esther alone or mixed. Here are some comparative examples used. The following monophosphate esters were used. The results are shown in Table 8. Compound m-1 Compound m-2 Table 8 Comparative examples of single use and mixed use of ester monophosphate 1314 Examples A to E, Comparative Examples A to D
After collecting the powder in the same manner as the alloy powder used in , argon at 25° C. was added to atmospheric pressure in a closed container, and the powder was immersed in butyl acetate from a bucket collector. Using 30 parts of the thus obtained alloy powder which had not been subjected to oxidation stabilization treatment, a magnetic paint and a magnetic recording medium were obtained in the same manner as in the Examples and Comparative Examples. Table 9 shows the characteristics of this product.
Shown below. Table 9 Examples of samples without surface oxidation stabilization treatment The methods for measuring the results in Tables 1 to 9 are shown. [Inflow rate: The unit of pressure rise measured by a pressure gauge when air flows into a closed container, skin Hg/min. 'o' Bulk specific gravity: Measured by placing the obtained alloy powder in a measuring cylinder without crushing it, in units of 1/3. 1 indicates something that was not measured because it was partially burned. Saturation magnetization: Value measured with the obtained alloy powder under an external magnetic field of 3,000 yen, unit, emu/unit. 8. Dispersibility: The obtained magnetic paint was heated in a filter of each average pore size at a pressure of 2k9/m, and when it was heated in the oven it was marked as ○, and when it was not passed in the oven it was marked as ×. [Surface quality: Total reflection at 45o and 450 measured by measuring the magnetic layer of the obtained magnetic recording material with a standard gloss meter. Bamboo Saturation magnetization: Value measured with the obtained magnetic recording material under an external magnetic field of 300°, unit, Gaussian. Demagnetization rate: When the obtained magnetic recording material is stored for one week at 60°C and 90% RH. Reduction rate of saturation magnetization.Unit: %'chi) Reproduction output: Reproduction output when an 8MHz reference signal is recorded on the obtained magnetic recording medium.When two tapes of C are used as a reference (B of 0.0). relative value of,
Unit, d Old 〇' Lee Blooming: The obtained magnetic recording material was wound with a tension of 2k9,
After storing it for a while, it was rewound and the surface was visually observed. From Table 1 and Figure 1, in order to obtain an alloy powder that is stable even when taken out into the atmosphere and has a large saturation magnetization, the air inflow rate should be 2 Hg/min or less, preferably 1 Hg/min.
It can be seen that it is necessary to perform surface oxidation stabilization treatment within 1 minute. It is thought that in Comparative Example B, oxidation stabilization was not carried out because the conditions were suddenly the same as when the sample was taken out into the atmosphere, and a portion of the sample was burned. - From Table 2, it can be seen that the surface oxidation stabilization treatment is preferably carried out at a bulk specific gravity of 1.0 or less, preferably 0.5 or less. It is thought that the saturation magnetization of Comparative Examples C and D was reduced because the samples were oxidized after being taken out into the atmosphere. Table 3 shows that when the ester phosphate according to the present invention is added, the dispersibility of the evaporation alloy powder improves, and the resulting magnetic recording material has good surface properties, a large maximum magnetic flux density, and a relatively small attenuation rate, resulting in a high reproduction output. I understand the big thing. On the other hand, as shown in Comparative Example 7 in Table 6, when the phosphate ester according to the present invention is not added, the evaporation method alloy powder has extremely poor dispersibility due to the binder, resulting in poor surface properties, maximum magnetic flux density,
It is clear that a magnetic recording medium with excellent demagnetization rate and reproduction output cannot be obtained. From Table 4, it can be seen that when R, R', and R' in the general formula have less than 6 carbon atoms, the demagnetization rate of the magnetic recording medium is large and the storage stability is poor. Furthermore, it can be seen that when the number of carbon atoms exceeds 22, blooming becomes a little easier. From Table 5, it can be seen that when the degree of polymerization of oxyethylene is 10 or more, the rate of loss of moisture is large and the storage stability is poor. It is also found that it becomes easier to perform fluming. Table 6 shows that if the amount of phosphate ester added according to the present invention is less than 0.3% by weight based on the alloy powder, the dispersibility of the alloy powder will not be improved, the furnace suitability will be poor, and the properties of the obtained magnetic recording material will be reduced. Bad things happen too. Moreover, it is understood that if it exceeds 5% by weight, bloomin occurs, which is not preferable. From Table 7, R and R' in the general formula
It is significant that a magnetic recording medium with good characteristics can be obtained even if the values are different. From Table 8, it can be seen that the use of monoester phosphate alone increases the demagnetization rate and deteriorates the storage stability of the magnetic recording medium. Furthermore, it is understood that if 67% or more of the phosphate ester according to the present invention is mixed, the adverse effects of the phosphate monoester will be reduced. It is also understood that a magnetic recording medium with good characteristics can be obtained by using a mixture of phosphoric acid gestal and triester. From Table 9, it can be seen that even in alloy powders not subjected to surface oxidation stabilization treatment, dispersibility is poor and storage stability is particularly poor unless the phosphoric acid ester according to the present invention is used. Furthermore, it can be seen that even if the 1'' acid ester according to the present invention is added, the storage stability is not sufficient and the reproduction output is not so high. Embodiments of the invention are described below. i) In the claims, the surface oxidation stabilization treatment is applied to the alloy powder with a cage specific gravity of 1.0 or less from a reduced pressure state to 2 m Hg
A magnetic recording material characterized by a process in which air is added at a rate of 1 minute to return the pressure to normal pressure. ii) In the claims, the surface oxidation stabilization treatment is
Alloy powder with a bulk specific gravity of 0.5 or less is poured into a container under reduced pressure.
A magnetic recording material characterized by a process in which air is added at a rate of g/min to return the pressure to normal pressure. liD A magnetic recording material according to the claims, characterized in that phosphate ester is contained in an amount of 0.3 to 5% by weight based on the magnetic material. M A magnetic recording material characterized in that 0.5 to 3% by weight of phosphate ester is contained based on the magnetic material.

[Brief explanation of drawings]

Figure 1 shows the relationship between the air inflow velocity during surface oxidation stabilization treatment and the saturation magnetization of the obtained alloy powder.
FIG. 2 shows the relationship between the amount of phosphate ester added and the reproduction output of the obtained magnetic recording medium. O2 diagram O diagram

Claims (1)

[Scope of Claims] 1. In a magnetic recording body provided with a magnetic layer in which ferromagnetic powder is dispersed in a binder on a non-magnetic support, an evaporation method in which the ferromagnetic powder is subjected to surface oxidation stabilization treatment. A magnetic material which is an alloy powder and contains in the magnetic layer 0.3 to 5% by weight of at least one kind of phosphate ester represented by the following general formulas I and II based on the alloy powder. record body. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (l, m, n are integers from 0 to 10, and R, R', R'' are saturated or unsaturated hydrocarbon groups having 6 to 22 carbon atoms.)