JPH028373B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to magnetic recording media such as magnetic tapes and magnetic sheets, and particularly to high-density magnetic recording media that have good wear resistance, storage stability, and high reproduction output. Conventionally, in magnetic recording media such as audio tapes and video tapes, magnetic fine powders such as Fe ₃ O ₄ and Fe--Co--Ni alloys are combined with vinyl chloride-vinyl acetate copolymers,
Dispersed and kneaded in a binder such as vinyl chloride-vinylidene chloride copolymer, polybutyl acrylate, butyl acrylate-acrylonitrile copolymer, cellulose resin, epoxy resin, polyurethane resin, etc. to form a coating solution, polyethylene It was coated on a film-like nonmagnetic support such as terephthalate, cellulose triacetate, polycarbonate, polypropylene, or polyvinyl chloride. Even when these binders are used alone or in combination, the wettability between the particle surface of the magnetic fine powder and the binder is insufficient, and the shape of the magnetic fine powder particles has acicular crystals. The dispersibility of magnetic fine powder in a binder tends to be poor for reasons such as The properties that should be possessed, such as abrasion resistance and storage stability, were not fully satisfied. In particular, in video tapes that require short wavelength recording, poor dispersion of magnetic powder in the magnetic layer can cause
This leads to a deterioration of the S/N ratio and a decrease in sensitivity, and since such recording media come into violent sliding contact with the magnetic head during recording and reproduction, the magnetic coating film is worn out by repeated use, and the magnetic powder contained in the coating film is worn out. They tend to fall off, causing undesirable results such as clogging of the magnetic head. Therefore, by controlling the particle size distribution of magnetic fine powder,
Various additives are used to improve the dispersibility of magnetic fine powder in a binder and to improve wear resistance. For example, Special Publication No. 41-18064,
43-186, 43-669, 47-15624, JP-A No. 49-53402, 49-58804, 49-84405,
As described in Publications No. 51-40904 and No. 52-70811, higher fatty acids, fatty acid amides, fatty acid esters, higher alcohols, metals, etc. A magnetic recording medium is produced by coating a magnetic powder-dispersed coating containing a magnetic powder, a sulfuric acid ester of a higher alcohol, polyethylene oxide, lecithin, etc. on the surface of a non-magnetic support. However, even with the addition of these additives, it has been difficult to obtain a magnetic recording medium with desirable characteristics such as improved magnetic properties, wear resistance, and long-term storage stability. That is, for example, when these additives are used in large amounts, the mechanical strength of the magnetic recording layer is reduced, which is an undesirable result. In addition, after the magnetic recording layer is formed, changes over time are observed, and the so-called blooming phenomenon occurs in which the additive gradually oozes out onto the surface of the magnetic recording layer, and tackiness is observed, resulting in unfavorable results in terms of storage stability. give. Furthermore, the dispersibility of the magnetic fine powder and the magnetic properties of the magnetic recording layer were not entirely satisfactory. An object of the present invention is to provide a novel magnetic recording medium that overcomes the above-mentioned drawbacks. Another object of the present invention is to provide a magnetic recording medium with good wear resistance. Still another object of the present invention is to provide a magnetic recording medium with a good S/N ratio. Still another object of the present invention is to provide a magnetic recording medium with high reproduction output. Still another object of the present invention is to provide a high quality magnetic recording medium with excellent storage stability. The above-mentioned objects of the present invention are to provide a magnetic recording layer on a support surface with a compound represented by the following general formula [] (hereinafter referred to as
This is achieved by a magnetic recording medium characterized by containing a compound of the present invention. General formula [] In the general formula [], R ₁ is an alkyl group having 8 or more carbon atoms, preferably 8 to 20 carbon atoms (e.g., octyl group, dodecyl group, octadecyl group), an alkenyl group having 8 or more carbon atoms, preferably 8 to 20 carbon atoms ( For example, dodecenyl group, oleyl group) or fluorine atom-substituted carbon atom number of 2 or more, preferably 2 to 10
represents an alkyl group, Z is -(CH ₂ -) _o [However,
n represents 2, 3 or 4. ], M represents a hydrogen atom or an alkali metal atom (e.g. potassium atom, sodium atom), R ₂ represents a hydrogen atom,
Alkali metal atoms (e.g. potassium atom, sodium atom), alkyl groups, preferably alkyl groups having 1 to 20 carbon atoms (e.g. methyl, ethyl, octyl, decyl, dodecyl), alkenyl groups (e.g. propenyl) , octenyl group,
oleyl group), an aryl group (eg, dodecylphenyl group), or a fluorine atom-substituted alkyl group, preferably a fluorine atom-substituted alkyl group having 2 to 20 carbon atoms. Next, specific examples of the compounds of the present invention will be given, but the compounds of the present invention are not limited thereto. Examples of synthesis of the compounds of the present invention are as follows. 1 Synthesis example of exemplified compound (1) A dianhydride was prepared from diethylenetriaminepentaacetic acid (DTPA), with a yield of 92% and a melting point of 168-169℃.
DTPA dianhydride was obtained. Airtight stirring device, dropping funnel, reflux tube with drying tube,
In a 500ml four-necked flask equipped with a thermometer,
After adding 0.1 mol of the above DTPA dianhydride and 240 ml of dry dimethylformamide (DMF) and dissolving them by heating, 80 ml of a dry DMF solution containing 0.1 mol of long-chain alcohol was added dropwise over 1 hour, and the mixture was further stirred at 85°C for 8 hours. 10 c.c. of water was added to this reaction solution and stirred at 65°C for 30 minutes to open the remaining DTPA anhydride ring. The reaction solution was dried under reduced pressure to remove insoluble matter in hot ethanol and hot cyclohexane, respectively, and then recrystallized from ethanol. The desired product was obtained with a yield of 5% and a melting point of 113-115°C. 2 Synthesis example of exemplified compound (4) Perform the same reaction as in 1 above, concentrate the reaction solution to 1/3 under reduced pressure, collect the crystals that precipitate when cooled to 25°C, and collect DMF: methanol (2: 1)
recrystallize from After heating and dissolving this in DMF again,
20 ml of water was added at 85°C to open the remaining DTPA anhydrous salt. When this reaction solution was cooled to 70°C, the precipitate was separated, and the evaporated dry product was mixed with water.
Recrystallized from DMF. Melting point 121-124 with 17% yield
The target product was obtained at ℃. 3 Synthesis example of exemplified compound (5) By performing the same operation as in 1 above, long-chain alcohol
Add 0.2 mol. The desired product was obtained as a white powder insoluble in hot ethanol. The yield was 75%. In addition to the above, the compound of the present invention can also be used in oil chemistry,
It can be easily synthesized according to the descriptions in Vol. 31, p. 47 (1982), Vol. 19, p. 984 (1970), etc. These compounds of the present invention may be used alone or in combination of two or more. The magnetic fine powder used in the present invention is a fine powder having a major axis of magnetic metal powder of 0.1 μ to 1 μ. Magnetic metals include metals such as iron, nickel, and cobalt, aluminum, cobalt, steel, Lead, magnesium, nickel, tin, zinc, antimony,
Beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten,
Examples include alloys of metals such as vanadium and mixtures thereof, metal compounds including metal oxides such as aluminum oxide, iron oxide, copper oxide, nickel oxide, zinc oxide, titanium oxide and magnesium oxide, and ferromagnetic materials such as ferrite. It will be done. Mainly used are fine powders of ferromagnetic metals such as ferrite and iron-cobalt-nickel alloys. In order to incorporate the compound of the present invention together with magnetic fine powder into a magnetic powder dispersion paint, at least one compound of the present invention is dissolved in a solvent such as toluene, methyl ethyl ketone, ethyl cellosolve, acetone, methanol, etc. By soaking the magnetic fine powder at a ratio of
The resulting fine magnetic powder is surface modified to provide a treated magnetic powder that can be easily wet-dispersed in organic solvents and binders. Alternatively, at least one compound of the present invention may be added to the magnetic powder-dispersed paint directly or dissolved in a suitable solvent. The compound of the present invention is usually 0.5 parts by weight to 30 parts by weight, preferably 0.5 parts by weight to 100 parts by weight of magnetic powder.
It is preferable to use it in a range of 10 parts by weight. When the compound of the present invention is less than 0.5 parts by weight,
The effect of the present invention is not significant, and if the amount exceeds 30 parts by weight, blooming phenomenon may occur, giving undesirable results. Generally, magnetic powder dispersion paint consists of ferromagnetic powder, binder,
The main components are the compound of the present invention and the coating solvent, and if necessary, additives such as a dispersant, a lubricant, an abrasive, and an antistatic agent are also contained. This magnetic powder-dispersed paint is prepared by dissolving and dispersing the above-mentioned composition in an organic solvent, and is coated onto the surface of the non-magnetic support to form a magnetic recording layer. Regarding the manufacturing method of the magnetic powder dispersion paint used in the present invention, please refer to Japanese Patent Publications No. 35-15, No. 39-26794, No. 43-186.
No. 47-28043, No. 47-28045, No. 47-
No. 28046, No. 47-28048, No. 47-31445, No. 48
- No. 11162, No. 48-21331, No. 48-33683,
It is described in detail in various publications such as Soviet Patent Specification No. 308033. 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, acrylonitrile-butadiene copolymer, polyamide resin, polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), styrene-butadiene copolymer, polyester resin, chlorovinyl ether-acrylic ester copolymer, amino resin, various synthetic rubber-based thermoplastic resins, and mixtures thereof, etc. is used. These resins are listed in Japanese Patent Publications No. 37-6877 and No. 39-
No. 12528, No. 39-19282, No. 40-5349, No. 40-
No. 20907, No. 41-9463, No. 41-14059, No. 41-
No. 16985, No. 42-6428, No. 42-11621, No. 43-
No. 4623, No. 43-15206, No. 44-2889, No. 44-
No. 17947, No. 44-18232, No. 45-14020, No. 45
-No. 14500, No. 47-18573, No. 47-22063, No. 47-22063, No. 47-18573, No. 47-22063, No.
No. 47-22064, No. 47-22068, No. 47-22069,
47-22070, 48-27886, U.S. Patent Nos. 3144352, 3419420, 3499789,
It is described in each 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 liquid, and after coating and drying, it becomes a polymer through reactions such as condensation and addition, and the molecular weight becomes infinite. Moreover, among these thermosetting resins or reactive resins, those that do not soften or melt before the resin is polymerized 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/high molecular weight diols/
These include mixtures of triphenylmethane triisocyanate, polyamine resins, and mixtures thereof. These resins are listed in Japanese Patent Publications No. 39-8103 and No. 40-
No. 9779, No. 41-7192, No. 41-8016, No. 41-
No. 14275, No. 42-18179, No. 43-12031, No. 44
-No. 28023, No. 45-14501, No. 45-24902, No. 45-24902, No. 45-14501, No. 45-24902, No.
No. 46-13103, No. 47-22067, No. 47-22072,
No. 47-22073, No. 47-28045, No. 47-28048,
Publications No. 47-28922, U.S. Patent No. 3144353, U.S. Patent No. 3320090, U.S. Patent No. 3437510, U.S. Patent No. 3597273,
It is described in the specifications of the same No. 3781210 and the same No. 3781211. These binders may be used alone or in combination, and other additives may be added as necessary. The mixing ratio of the ferromagnetic fine powder and the binder is 10 to 400 parts by weight, preferably 30 to 200 parts by weight, per 100 parts by weight of the ferromagnetic fine powder. If there is too much binder, the recording density of the magnetic recording medium will decrease, and if it is too little, the strength of the magnetic recording layer will be poor, resulting in undesirable situations such as decreased durability and powder falling off. In addition to the compound of the present invention, a binder, and the ferromagnetic fine powder, additives such as a dispersant, a lubricant, an abrasive, an antistatic agent, etc. are added to the magnetic powder-dispersed paint forming the magnetic recording layer. It's okay. Dispersants that may be used include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, etc.
12-18 fatty acids (R ₃ COOH, R ₃ is the number of carbon atoms
(11 to 17 alkyl groups); metal soaps made of alkali metals (Li, Na, K, etc.) or alkaline earth metals (Mg, Ca, Ba, etc.) of the above-mentioned fatty acids; lecithin, etc. are used. In addition to these, higher alcohols having 12 or more carbon atoms and sulfuric esters can also be used. These dispersants are binders
It is added in an amount of 1 to 20 parts by weight per 100 parts by weight. These dispersants are disclosed in Japanese Patent Publication Nos. 39-28369 and 44
-17945, 48-15001, U.S. Patent No.
It is described in the specifications of No. 3587993 and No. 3470021. Examples of lubricants include silicone oil, carbon black, graphite, carbon black graft polymer, molybdenum disulfide, tungsten disulfide, monobasic fatty acids having 12 to 16 carbon atoms, and carbon Number of atoms is 21-23
Fatty acid esters (so-called waxes) consisting of monohydric alcohols can also 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, special public relations
Publications such as Publication No. 23889 and No. 43-81543, U.S. Patent No. 3470021, U.S. Patent No. 3492235, U.S. Patent No. 3497411,
Same No. 3523086, Same No. 3625760, Same No. 3630772,
Specifications of No. 3634253, No. 3642539, and No. 3687725, IBM Technical Disclosure
BulIetin Vol.9, No.7, Page779 (December 1966);
Described in ELEKTRONIK 1961 No. 12, Page 380, etc. The abrasives used are commonly used materials such as 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 diameter of 0.05 to 5 μm, particularly preferably 0.1 to 2 μm. These abrasives are added in an amount of 7 to 20 parts by weight per 100 parts by weight of the binder. These abrasives are
Publication No. 49-115510, U.S. Patent No. 3007807, U.S. Pat.
3041196, 3687725 specifications, British patent no.
1145349, West German patent (DT-PS)
It is described in the specification of No. 853211. Antistatic agents used 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; and high-grade surfactants. Cationic surfactants such as alkylamines, quaternary ammonium salts, pyridine, other heterocycles, phosphoniums or sulfoniums; Contains acidic groups such as carboxylic acids, sulfonic acids, phosphoric acids, sulfuric ester groups, phosphoric ester groups, etc. Anionic surfactant; amino acids, aminosulfonic acids,
Ampholytic activators such as sulfuric acid or phosphoric acid esters of amino alcohols are used. These surfactants that can be used as antistatic agents are US Pat. Nos. 2271623, 2240472,
No. 2288226, No. 2676122, No. 2676924, No. 2676975, No. 2691566, No. 2727860,
Same No. 2730498, Same No. 2742379, Same No. 2739891,
Same No. 3068101, Same No. 3158484, Same No. 3201253,
Same No. 3210191, Same No. 3294540, Same No. 3415649,
Same No. 3441413, Same No. 3442654, Same No. 3475174,
Patent No. 3545974, West German Patent Publication (OLS) No. 1942665, British Patent No. 1077317
No. 1198450, "Synthesis of Surfactants and Their Applications" by Ryohei Oda et al. (Maki Shoten 1964 edition); "Surf S Active Agents" by AW Bayley (Interscience Publications) Yong Incorporated (1958 edition);
TP Sisley, “Encyclopedia of Surf Active Agents, Vol.
Volume" (Chemical Publishing Company, 1964 edition); "Surfactant Handbook" 6th edition (Sangyo Tosho Co., Ltd., December 20, 1964). These surfactants may be added alone or in combination. These are used as antistatic agents, but may be used for other purposes as needed.
For example, it may be used for dispersion, improving magnetic properties, improving lubricity, and as a coating aid. To form the magnetic recording layer, the above-mentioned composition is dissolved in an organic solvent and applied as a coating solution onto the surface of the non-magnetic support. 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 diethyl ether, glycol dimethyl ether, glycol monoethyl ether, and dioxane; tar systems (aromatic hydrocarbons) such as benzene, toluene, and xylene; methylene chloride, ethylene chloride, Halogenated hydrocarbons such as carbon chloride, chloroform, ethylene chlorohydrin, and dichlorobenzene can be used. The material for the support may be any non-magnetic material, such as polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene, and cellulose derivatives such as cellulose triacetate and cellulose diacetate. , plastics such as polycarbonate, non-magnetic metals such as Cu, Al, and Zn, and ceramics such as glass, porcelain, and earthenware. 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.
50 μm, and 0.5 in the case of 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 nonmagnetic support may be coated with a so-called backcoat on the surface opposite to the coated surface on which the magnetic layer is provided for the purpose of preventing static electricity, preventing transfer, and the like. Regarding back coats, for example, U.S. Patent No.
No. 2804401, No. 3293066, No. 3617378, No. 3062676, No. 3734772, No. 3476596,
Same No. 2643048, Same No. 2803556, Same No. 2887462,
Same No. 2923642, Same No. 2997451, Same No. 3007892,
It is described in the specifications of the same No. 3041196, the same No. 3115420, the same No. 3166688, etc. Further, the form of the support may be tape, sheet, card, disk, drum, etc., and various materials are selected as necessary depending on the form. The magnetic fine powder and the above-mentioned binder, dispersant, lubricant, abrasive, antistatic agent, solvent, etc. are kneaded to form a magnetic powder-dispersed paint. During kneading, the magnetic fine powder and the above-mentioned components are all fed into a kneader simultaneously or individually one after another. For example, there is a method in which magnetic fine powder is first added to a solution 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 powder-dispersed paint. Various kneaders are used for kneading and dispersing. For example, two-roll mill, three-roll mill, ball mill, pebble mill, sand grinder,
Szegvari attritor, high speed impeller disperser,
These include high-speed stone mills, high-speed impact mills, disper kneaders, high-speed mixers, homogenizers, and ultrasonic dispersers. The technology related to kneading and dispersion is written by TCPATTON.
Faint FIow and Pigment Dispersion (1964)
published by John WiIIey & Sons).
It is also described in the specifications of US Pat. No. 2,581,414 and US Pat. No. 2,855,156. The coating method for coating the magnetic powder dispersion coating onto a non-magnetic support to form a magnetic recording layer is as follows:
Air doctor coat, blade cord, air knife coat, squeeze coat, impregnation 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. A detailed explanation is given in "Coating Engineering" published by Asakura Shoten, pages 253 to 277 (1968).
(published on March 20, 2016). By such a method, the magnetic recording layer coated on the support is subjected to treatment to orient the magnetic fine powder in the layer during or after coating the magnetic dispersion paint, and then the formed magnetic recording layer is processed. Dry the layer. Further, if necessary, the magnetic recording medium according to the present invention is manufactured by subjecting it to surface smoothing processing or cutting it into a desired shape. In this case, the orientation magnetic field is approximately 500 AC or DC
~2000 gauss or so, and the drying temperature is approximately 50~100 gauss
℃, and the drying time is about 3 to 10 minutes. A method for orienting magnetic fine powder is also described in the following patent publications and specifications. For example, US Patent No. 1949840, US Patent No. 2796359
No. 3001391, No. 3172776, No. 3172776, No. 3001391, No. 3172776, No.
Specifications of No. 3416949, No. 3473960, No. 3681138, Japanese Patent Publication No. 32-3427, No. 39-28368, No. 40-23624, No. 40-23625, No. 41-13181,
These include Publications No. 48-13043 and No. 48-39722. 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 videotapes, it is oriented at an angle of 30° to 90° with respect to the length. A magnetic recording medium using the compound of the present invention is a high-quality magnetic recording medium that has good wear resistance and storage stability, and has a reproduction output with a high S/N ratio. The present invention will be explained in more detail below using examples. The components, proportions, order of operations, etc. shown here may be changed as appropriate, and the present invention is not limited to the following examples. In addition, in the following examples, all "parts" indicate "parts by weight." Example 1 Exemplary compounds (1) to exemplified compounds shown in Table 1 below
(5) was diluted with 500 parts of methanol, 100 parts of magnetic fine powder was added, and the mixture was mixed and dispersed. Thereafter, it was filtered, air dried, and then dried under reduced pressure at 80°C to obtain the treated magnetic powder No. shown in Table 1.
1 to 5 were produced.

[Table] When a small amount of each of the above treated magnetic powder Nos. 1 to 5 was sampled and a flashing test was performed in a water-toluene system, the treated magnetic powder completely migrated to the organic layer. Since untreated powder remains in the water layer, treated magnetic powder modifies the surface of the magnetic powder,
It was found that it can be well wetted with organic solvent-based binders. Using the treated magnetic powder Nos. 1 to 5 obtained above, magnetic tapes were prepared with the following compositions. Treated magnetic powder (No. 1 to 5) 90 parts Vinylidene chloride-acrylonitrile copolymer
16 parts polyurethane 7 parts silicone oil 3 parts carbon black 3 parts methyl isobutyl ketone 75 parts methyl ethyl ketone 175 parts The above composition was placed in a ball mill, and after thorough mixing and dispersion, a blackish brown magnetic powder dispersed paint was obtained. This paint was applied to one side of a 15μ polyethylene terephthalate film while applying a magnetic field of 1200 Gauss to a dry film thickness of 6μ, and dried. Each of the wide magnetic waves thus obtained was supercalendered and slit to a width of 12.7 mm to obtain a videotape. The tapes produced using the treated magnetic powders No. 1 to No. 5 are referred to as inventive samples No. 1 to No. 5, respectively. Example 2 Exemplary compounds (1) to (5) shown in Table 2 below
was diluted with 500 parts of methanol, and a magnetic alloy (Fe-Co
-100 parts of Ni) were added and mixed and dispersed. Thereafter, it was filtered, air-dried, and dried under reduced pressure to produce treated magnetic powders Nos. 6 to 10 shown in Table 2.

[Table] Using the thus obtained treated magnetic powder Nos. 6 to 10, magnetic powder dispersed paints were prepared with the following compositions. Treated magnetic powder (No. 6 to 10) 75 parts Partially hydrolyzed vinyl chloride-vinyl acetate copolymer 7.5 Polyurethane 7.5 parts Silicone oil 1.5 parts Methyl ethyl ketone 70 parts Toluene 60 parts Cyclohexane 5 parts Place the above composition in a ball mill and mix thoroughly. After dispersion, 3 parts of tolylene diisocyanate was added and mixed uniformly to obtain a magnetic powder dispersed paint. This paint was applied to one side of a 15μ polyethylene terephthalate film while applying a 1200 Gauss magnetic field to a dry film thickness of 5μ, and dried. Each of the wide samples thus obtained was designated as Invention Sample No. 1 of Example 1.
Samples Nos. 6 to 10 of the present invention were prepared in the same manner as above. Example 3 Untreated Co-containing Fe ₃ O ₄ powder 90 parts Vinylidene chloride-acrylonitrile copolymer 16 parts Polyurethane 7 parts Carbon black 3 parts Exemplary compound (1) 3 parts Methyl isobutyl ketone 75 parts Methyl ethyl ketone 175 parts The above composition was ball milled. After thorough mixing and dispersion, a blackish brown magnetic dispersion paint was obtained. A videotape was obtained using this paint in the same manner as Sample No. 1 of Example 1. This tape was used as Invention Sample No. 11.
shall be. Comparative Example 1 A videotape was produced in the same manner as inventive sample No. 1 of Example 1, except that untreated Co-containing Fe ₃ O ₄ was used instead of the surface-modified treated magnetic powder. This is designated as comparative sample No. 1. Comparative Example 2 A videotape was produced in the same manner as inventive sample No. 6 of Example 2, except that an untreated magnetic alloy (Fe-Co-Ni) was used instead of the surface-modified treated magnetic powder. did. This is designated as comparative sample No. 2. Comparative Example 3 End-treated Co-containing Fe ₃ O ₄ powder 90 parts Vinylidene chloride-acronitrile copolymer 16 parts Polyurethane 7 parts Carbon black 3 parts Lecithin 5 parts Methyl isobutyl ketone 75 parts Methyl ethyl ketone 175 parts The above composition was placed in a ball mill. After thorough mixing and dispersion, a blackish brown magnetic powder dispersed paint was obtained. Using this paint, a videotape was obtained in the same manner as inventive sample No. 6 of Example 2. Comparative sample of this tape
Set it as No.3. Comparative Example 4 Finished magnetic alloy (Fe-Co-Ni) 75 parts Partially hydrolyzed vinyl chloride-vinyl acetate copolymer 7.5 parts Polyurethane 7.5 parts Lecithin 5 parts Methyl ethyl ketone 70 parts Toluene 60 parts Cyclohexane 5 parts The above composition was milled into a ball mill. After adding and sufficiently mixing and dispersing, a magnetic powder-dispersed paint was obtained. Using this paint, a videotape was obtained in the same manner as inventive sample No. 6 of Example 2. This tape is designated as comparative sample No. 4. The comparative test results for each of these samples are summarized in Table 3.

[Table] From the above results, the magnetic recording medium according to the present invention is a high-density magnetic recording medium that has better wear resistance, storage stability, and reproduction output with a high S/N ratio than conventional ones. I understand that there is something.

Claims (1)

[Claims] 1. The magnetic recording layer on the support surface has the following general formula []
A magnetic recording medium characterized by containing a compound represented by: General formula [] [In the formula, R ₁ is an alkyl group or alkenyl group having 8 or more carbon atoms, or an alkyl group substituted with a fluorine atom, and Z is -(CH ₂ -) _o (however, n
represents 2, 3 or 4), M represents a hydrogen atom or an alkali metal atom, and R ₂ represents a hydrogen atom, an alkali metal atom, an alkyl group, an alkenyl group, an aryl group or a fluorine atom-substituted alkyl group. ]