JPS605420A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the wear resistance, the still durability and the stability of oxidation and to prevent a leaking phenomenon of a magnetic layer, by providing a magnetic layer containing the metallic magnetic powder having no change of a differential heat curve at least up to a specific temperature, the fatty acid having a limited number of carbon atoms and the fatty acid ester having the sum of carbon atoms within a specific range respectively. CONSTITUTION:The metallic magnetic powder is reformed so that it is stabilized thermally at least up to 80 deg.C or to oxidation and without deteriorating greatly the magnetic characteristics. It is desirable to use the monobasic fatty acid having 10-18 atoms in terms of maintenance and stability, etc. The fatty acid ester having 15-32 carbon atoms in terms of all carbon atoms in a molecular formula. Then 0.5-10pts.wt. monobasic and fatty acid ester can be contained to 100pts.wt. magnetic powder. The magnetic layer of a magnetic recording medium is formed by coating a magnetic coating material onto a supporter. This coating material is obtained by kneading and dispersing the metallic magnetic powder, the monobasic fatty acid and the fatty acid ester into a solvent.

Description

Detailed Description of the Invention (a) Industrial Application Field: The present invention relates to a magnetic recording medium using metal magnetic powder, which has particularly excellent wear resistance, methyl durability, and oxidation stability, and has a magnetic layer with excellent wear resistance, methyl durability, and oxidation stability. [Regarding a magnetic recording medium that does not cause bleeding J]

(b) Prior Art: A magnetic recording medium is usually made by coating a magnetic powder together with a binder component on a support such as a polyester tape and drying the coating to form a magnetic layer.

As for the magnetic powder contained in the magnetic layer, metal magnetic powder is superior to oxidized magnetic powder in that it can provide large saturation magnetization, squareness, and coercive force. However, the metal magnetic powder with (1) is more easily oxidized than the oxidized magnetic powder. Particularly when performing high-density recording, in order to increase the degree of filling per unit volume in the magnetic layer, if the particle size is reduced to 1μ or less, not only will the dispersibility decrease, but the surface area of the magnetic powder will increase, and the magnetic powder will become even more dense. It is easily oxidized and becomes easily chained, its magnetic properties deteriorate over time, and its storage stability and still durability decrease.

In addition, (1) When recording or reproducing information on a magnetic recording medium, the magnetic layer of the magnetic recording medium is made to run so as to come into contact with a magnetic head, a guide member, etc. In particular, in the case of magnetic recording videotape, magnetic tape (i.e. magnetic recording medium)
A method is adopted in which the magnetic tape is kept stationary and a magnetic head is repeatedly slid at the same location on the magnetic tape at high speed with strong contact pressure to reproduce a still image. When a magnetic recording medium is used under these conditions, the magnetic tape when running is
The temperature rises to 50-60°C due to frictional heat. As a result, the magnetic layer of the magnetic recording medium becomes soft, the magnetic layer is severely worn out, and running friction increases rapidly, making it unable to withstand running.

(2) Furthermore, since the magnetic tape reaches a high temperature of 50 DEG C. to 60 DEG C. as mentioned above, the metal magnetic powder in the magnetic layer is further oxidized, and the still durability of the magnetic tape is reduced. On the other hand, (2) it is known to previously contain a lubricant in the magnetic layer in order to improve the wear resistance of the magnetic layer. For example, in the specification of Japanese Patent Publication No. 51-39081, silicone oil, molybdenum disulfide, graphite, a monobasic fatty acid having 12 to 16 carbon atoms, and a monobasic fatty acid having 3 to 12 carbon atoms are contained in the magnetic layer. It is described that a fatty acid ester consisting of a monohydric alcohol, a fatty acid ester consisting of a monobasic fatty acid having 18 carbon atoms and a lower or intermediate monohydric alcohol is contained. However, even if such a lubricant is contained in the magnetic layer, the methyl durability in the case of silicone oil is only 1 minute or less, and that in the case of containing fatty acid ester alone is about 2 minutes. be. In addition, when fatty acids are added, the still durability is about 5 minutes, but after the magnetic layer is formed, the additive ``oozes'' onto the surface of the magnetic layer.
In view of these circumstances, the present inventors observed the surface state of metal magnetic powder using an electron microscope and analyzed the differential thermal curve in order to investigate the oxidation stability of metal magnetic powder. As a result of investigation from both the thermal stability and thermal stability measurements, it was found that there is a close relationship between the two.

In other words, the oxidation stability of metal magnetic powder has traditionally been
Although it depends on the original properties of the magnetic powder, the biggest factor is said to be pinholes on the surface of the magnetic powder.

Conventionally known metal magnetic powder (with a differential thermal curve of 20°C to 70°C)
Metal magnetic powder that varies with °C. ) through an electron microscope at a magnification of 30,000 times, the state shown in the photograph in Figure 1 can be observed. From FIG. 1, it can be seen that the metal magnetic powder is an aggregation of many acicular magnetic powder particles. Moreover, the surface of each magnetic powder particle piece is relatively smooth. On the other hand, an electron micrograph X (30,000x) of a metal magnetic powder whose differential thermal curve does not change up to at least 80°C (in other words, is stable) shows the state shown in Figure 2. The surface of the acicular magnetic powder particle pieces is quite rough, and it can be assumed that there are fewer pinholes.The metal magnetic powder whose differential thermal curve does not change up to at least 80"C has low oxidation stability. I learned that it was expensive.

Furthermore, as shown in the specification of Japanese Patent Publication No. 51-39081, fatty acid esters and carbon When a fatty acid consisting of a monobasic fatty acid with 18 atoms and a low or intermediate monohydric alcohol is used as a lubricant, the methyl durability of the magnetic recording medium is improved, but at temperatures above 30°C, "bleeding" (
(Pluming), causing adhesion to the running sliding parts,
It is not usable due to the sudden increase in running friction. However, according to the experimental results of the present inventors, metal magnetic powder and
When a fatty acid having 10 to 18 carbon atoms and a fatty acid ester having a total number of carbon atoms of 15 to 32 are used, the magnetic recording medium has good still durability even at high temperatures of 50 to 60°C. The present invention was achieved based on the discovery that there is no "oozing" phenomenon and low running friction.

(e) Object of the invention: The object of the present invention is to provide a magnetic recording medium which has excellent wear resistance, still durability and oxidation stability, and which does not cause the "bleed" phenomenon in the magnetic layer.

Cd) Structure of the invention: The object of the present invention is to provide on a support a metal magnetic powder whose differential thermal curve does not change up to at least 80°C, a fatty acid having 10 to 18 carbon atoms, and a metal magnetic powder having a carbon atom number of 10 to 18. Total is 1
This is achieved by providing a magnetic layer containing 5 to 32 fatty acid esters.

Magnetic powders that can be used in the magnetic layer of the magnetic recording medium of the present invention include Fe-Ni-Co alloy, Fe-Mn-Zn alloy,
Fe-Go-Ni-P alloy, Fe-Ni-Zn alloy, F
e-N1-Cr-P alloy, Fe-Go-Ni-Cr
Alloy, Fe-C.

-P alloy, Fe-Ni alloy, Fe-Ni-Mn alloy, Co-Ni alloy, Co-N1-F' gold alloy Fe-A
Examples include metal magnetic powders such as t alloy, Fe-Mn-Zn alloy, and Fe-At-P alloy.

The differential thermal curve is at least 80'c-! The following method is available as a method for obtaining stable metal magnetic powder (hereinafter simply referred to as "magnetic powder" for convenience) that does not change with l.

(1) As shown in FIG. 3, the outer surface of the metal magnetic powder surface treatment is coated with a thermally stable polymer compound (for example, polyamide resin) 2.

(2) As shown in FIG. 4, a method of slowly oxidizing the outer surface of metal magnetic powder particles 1 to form a stable oxide layer 3.

(3) Add various additives to the alloy components of the metal magnetic powder, such as nickel, aluminum, silicon, magnesium,
This is a method in which various elements such as copper and phosphorus and/or compounds thereof are added by inclusion or deposition.

The metal magnetic powder contained in the magnetic layer of the magnetic recording medium of the present invention may be prepared by any of the above methods, but mainly (
It is preferable that the magnetic powder obtained by method 3) is used as the basis, and it is preferable that one or both of methods (1) and (2) be used as an auxiliary method, if necessary. In other words, in the magnetic powder obtained by method (1), the proportion of the metal magnetic powder (magnetic material) itself per unit volume of the magnetic powder is small, and the magnetometer per unit volume of the magnetic layer is The size is smaller than when using metal magnetic powder that does not contain metal magnetic powder. For example, in a coated magnetic recording medium in which the magnetic layer is mainly formed of magnetic powder and a binder, the metal magnetic powder to be contained in the magnetic layer is
When thermal stability (or oxidative stability) is achieved by the method described in (1) above, the actual filling rate of the magnetic material in the magnetic layer becomes low, making it difficult for recording media to perform high-density recording. In some cases, it is not good. However, the magnetic powder obtained by method (1) requires special measures for the binder system (use of a special binder, special dispersant, etc.), and has the disadvantage of complicating production.

The magnetic powder obtained by method (2) also has the same drawbacks as the magnetic powder obtained by method (1).

In other words, the volume of the part that is not slowly oxidized, in other words, the volume of the non-oxidized part that contributes to magnetization, is smaller than the volume of the magnetic powder, as in the case of (1), so the substance of the magnetic material in the magnetic layer is smaller than the volume of the magnetic powder. The filling rate will decrease.

Therefore, the magnetic powder used in the magnetic layer of the magnetic recording medium of the present invention is thermally stable (or oxidatively stable).
It is preferable that it has (1
) or (2), or a combination of these methods is preferred.

In addition, methods (1) and (2) above or other methods may be used, such as using magnetic powder with a substance (whether a low molecular compound or a high molecular compound) that has the property of filling the pin pole of the magnetic powder. It is possible to form a thin film on the surface of the magnetic powder by immersion in a solution of (1), immersion, or the method described in (1) above, but the thermal stability may not be sufficient. ), this can be chemically or physically reacted to form a thermally or oxidatively stable magnetic powder. It is also possible to combine anti-corrosion treatment with silicone oil, etc. In short, the metal magnetic powder has been modified to be thermally or oxidized stable up to at least 80°C without significantly changing its magnetic properties, and the magnetic powder of the present invention has been It is a metal magnetic powder whose differential thermal curve does not change with temperature.

Among the above-mentioned methods (1) to (3) and other methods, method (3), which is mainly used, will be described in detail.

Various elements and/or compounds are added to the metal components of the metal magnetic powder (here, metal components mainly mean components other than carbon, hydrogen, oxygen, etc. that are not detected by an X-ray microanalyzer). In the method (3) of adding aluminum, silicon, aluminum,
Nickel and these compounds can be listed.

Differential thermal curve t: When a metal magnetic powder is heated at a constant rate with a thermally stable reference material such as alumina or quartz, the temperature difference that occurs between the two is measured and the energy state of the two is determined. The measurement method is described in detail in, for example, Nippon Kagaku Gold Wire: "New Experimental Chemistry Course 2, Basic Technology."

When the additive is At and/or its compound, the amount of addition is such that the proportion of At atoms (for example, At if the additive is At203) in the metal component of the metal magnetic powder is equal to the total metal component. It is in the range of 0.05 to 20 atomic weight %, particularly preferably in the range of 1 to 20 atomic weight %, based on the atomic weight of . If the At atom content is less than 0.5 atomic weight %, the thermal or oxidative stability of the obtained metal magnetic powder will be insufficient, and the characteristics of the magnetic recording medium prepared using this magnetic powder, such as storage stability, Durability becomes insufficient.

In addition, when using the St element and/or its compound as an additive, the metal component portion (At, St, S % Fe5Ni
, Co, Ra, Hf, Cu, Ps Zns
The weight percentage occupied by Sl atoms is 1% by weight or less, preferably 0.5% by weight or less, and may be 0.1% or less depending on the case. If Si is outside this range, it may be difficult to modify the magnetic powder.

Furthermore, when Ni element and/or its compound is contained as an additive, it is desirable that the upper limit is 30 atomic weight % or less, preferably 20 atomic weight % or less from the viewpoint of magnetic properties.

Further, as the fatty acid having 10 to 18 carbon atoms that can be used in the magnetic layer of the magnetic recording medium of the present invention, pri-7 acid (C
o I (+ o COOH containing lauric acid (CIIH!3
C00H), myristic acid (C,, H,, (?00)
9, Valmitic acid (CI!H,, C00I-1λ Stearic acid (C,, H3, C00H), Sebacic acid (1-1
00C(C)l, ), C00H), oleic acid, elaidic acid, and the like. Among these, monobasic fatty acids are preferred from the viewpoint of storage stability, and saturated fatty acids are preferred. This fatty acid has 10 carbon atoms
If the number is less than 18, the still durability of the produced magnetic recording medium will be poor, and if it is more than 18, the compatibility with the binder etc. will be poor and the melting point will be high.

It tends to harden on the surface of the sexual layer. Further, fatty acid esters having a total number of carbon atoms of 15 to 32 have a total number of carbon atoms of 15 to 32 in the molecular formula. As such a fatty acid ester, myristic acid pf /I/ (C
,3H2□C00C,H,), Butylaurate # (C
.

H23COOC4H0), propyl myristate (C1
3■I2□C00C1)I, ), palmy acid phther (C,51(3,C00C4H,), propyl stearate (C,,H3,C00clH,''), stearate propyl (C17H3,C00C4H9 ), ethyl stearate (C1□H35COOC2I, ), butyl behenate (C21H4:IC0OC4H,), and the like.

The fatty acid ester has 12 to 22 carbon atoms.
A composition consisting of a fatty acid moiety of 1 to 10 carbon atoms and an alcohol moiety having 1 to 10 carbon atoms is clever in that it provides synergistic effects such as compatibility with a binder and the like and slipperiness with the fatty acid.

When the total number of carbon atoms in this fatty acid ester is less than 15, the slipperiness of the magnetic layer is poor, and when the total number of carbon atoms is more than 32, the reproduction output of the magnetic recording medium is likely to decrease. is magnetic powder 1
It may be contained in an amount of 0.5 to 10 parts by weight per 00 parts by weight. If it is less than 0.5 parts by weight, the slipperiness of the magnetic layer may not be sufficient, and if it is more than 10 parts by weight, fatty acids may ooze out onto the surface of the magnetic layer, which may also lead to a decrease in output. There is. This relationship is shown in FIG.

Furthermore, the ratio when using the above-mentioned basic fatty acids and fatty acid esters ranges from 7/3 to 2/8. Outside this range, still durability may be insufficient. FIG. 6 shows the relationship between the fatty acid/fatty acid ester mixing ratio and still image reproduction time (in other words, still durability).

The magnetic layer of the magnetic recording medium according to the present invention is prepared by applying a magnetic paint obtained by kneading and dispersing the metal magnetic powder in a solvent together with a binder, the basic fatty acid, and the fatty acid ester onto a support. It is formed by

Examples of binders that can be used in the magnetic layer of the magnetic recording medium of the present invention include thermoplastic resins, thermosetting resins, reactive resins, electron beam curable resins, and mixtures thereof.

The thermoplastic resin has a softening temperature of 150°C or less and an average molecular weight of 10,000 to 200. QOO, degree of polymerization is about 20
About 0 to 2,000, such as vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-chloride vinylidene copolymer, methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-ethylene 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 copolymers, polyester resins, chlorovinyether-acrylic acid ester copolymers, amine resins, various synthetic rubber-based thermoplastic resins, and mixtures thereof. etc. are used.

These resins are disclosed in Japanese Patent Publications Nos. 37-6877 and 39-1.
No. 2528, No. 39-19282, No. 40-5349
No. 40-20907, No. 41-9463, No. 4
No. 1-14059, No. 41-16985, No. 42-6
No. 428, No. 42-11621, No. 43-4623, No. 43-15206, No. 44-2889, No. 44
-17947, 44-18232, 45-14
No. 020, No. 45-14500, No. 47-18573
No. 47-22063, No. 47-22064, No. 47-22068, No. 47-22069, No. 47-
22070, US Pat. No. 48-27886, US Pat. No. 3.144,352, US Pat. No. 3.419,420
No. 3.499,789, No. 3.713
, No. 887.

i as a thermosetting resin or reactive resin in the state of a coating liquid.
The molecular weight may be from 0,000 to 200,000, and the molecular weight may be increased to infinity by a reaction such as condensation or addition after coating and drying.

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

Specifically, for example, phenolic resin, epoxy resin,
Polyurethane curable resins, urea resins, melamine resins, alkyd resins, silicone resins, acrylic reactive resins, mixtures of high molecular weight polyester resins and incyanate prepolymers, mixtures of methacrylate copolymers and diisocyanate prepolymers, polyester polyols and These include mixtures of polyisocyanates, urea formaldehyde resins, mixtures of low molecular weight glycols/high molecular weight diols/triphenylmethane triincyanates, polyamine resins, and mixtures thereof.

These resins are disclosed in Japanese Patent Publication Nos. 39-8103 and 40-9.
No. 779, No. 41-7192, No. 41-8016,
No. 41-14275, No. 42-18179, No. 43
-12081, 44-28023, 45-14
No. 501, No. 45-24902, No. 46-13103
No. 47-22067, No. 47-22072, No. 7-22073, No. 47-28045, No. 47
-2so4s, US Patent No. 47-28922, US Patent No. 3,144,353, US Patent No. 3320990, US Patent No. 3,437,510, US Patent No. 3,597,273
No. 3,781,210, No. 3,781,21
It is stated in the specification of No. 1.

Examples of electron beam irradiation-curable resins include unsaturated prepolymers,
For example, maleic anhydride type, urethane acrylic type, epoxy acrylic type, polyester acrylic type, polyether acrylic type, polyurethane acrylic type, polyamide acrylic type, etc., or as a polyfunctional monomer, ether ° acrylic type, urethane acrylic type, epoxy acrylic type , phosphate ester acrylic type, aryl type, hydrocarbon type, etc.

The above-mentioned binders may be used alone or in combination, and other additives may be added as necessary.

The mixing ratio of magnetic powder and binder is 100% magnetic powder.
The binder is mixed in an amount of 5 to 400 parts by weight, preferably 10 to 200 parts by weight. If the amount of binder mixed is too large, the recording density when used as a magnetic recording medium will decrease, and if it is too small, the strength of the magnetic layer will be poor, resulting in undesirable problems such as decreased durability and powder falling off.44 FM
occurs.

Furthermore, various hardening agents can be added to the magnetic layer to improve the magnetic properties of the magnetic recording medium.

For example, a polyfunctional isocyanate or the like can be contained.

Examples of the polyfunctional incyanate include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, an adduct of diisocyanate and trivalent polyol, or a pentamer of diisocyanate. .

Furthermore, K consists of an adduct of 3 moles of tolylene diisocyanate and 1 mole of trimethylolpropane, an adduct of 3 moles of metaxylylene diisocyanate and 1 mole of trimethylolpropane, a pentamer of tolylene diisocyanate, and 2 moles of tolylene diisocyanate. Pentamers and the like can be used.

In addition to the magnetic powder, binder, and curing agent described above, additives such as a dispersant, an abrasive, and an antistatic agent may be added to the magnetic layer.

Dispersants used include lecithin, phosphate esters,
Amine compounds, alkyl sulfates, fatty acid amides,
These include higher alcohols, polyethylene oxide, sulfosuccinic acid, known surfactants, and their salts.
) can also be used.

These dispersants may be used alone or in combination of two or more. These dispersants are added in an amount of 1 to 20 parts by weight per 100 parts by weight of the binder.

Regarding these dispersants, Japanese Patent Publications Nos. 41-18064, 49-84405, 52-70811, 5
No. 7-1048 specification, U.S. Patent No. 3,587,9
No. 93, No. 3,470,021 Iv (B'i1 isobaric).

Commonly used materials as abrasives include fused aluminum, silicon carbide, chromium oxide, corundum, artificial corundum, artificial diamond, garnet, and emery (main components: corundum and magnetite). These abrasives have an average particle size of 0.05 to 5 μm, preferably 0.1 to 2 μm. These abrasives are added in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the binder. These abrasives are described in JP-A-49-115510, U.S. Patent No. 3,
No. 007,807, No. 3,041,196, No. 3
．． No. 687,725, British Patent No. 1,145,349, and West German Patent (DT-PS) No. 853.211.

If necessary, antistatic agents include conductive powders such as graphite, carbon black, tin oxide-antimony oxide compounds, tin oxide-titanium oxide-antimony oxide compounds, carbon black graft polymers, and natural substances such as saponin. Surfactant: Nonionic surfactant such as alkylene oxide type, glycerin type, glycidol type etc.: Cationic surfactant such as higher alkylamines, quaternary pyridine, other heterocycles, phosphonium or sulfonium type: Carboxylic acid, Anionic surfactants containing acidic groups such as sulfonic acid, phosphoric acid, sulfuric ester groups, phosphoric ester groups, etc.Amphoteric surfactants such as diamino acids, amino sulfonic acids, sulfuric acid or phosphoric esters of amino alcohols, etc. are used. Surfactants that can be used as antistatic agents are described in U.S. Pat.
, 240,472, 2,288,226, 2,676,924, 2,676,975, 2,691,566, 2,727,860 ,
Same No. 2.730,498, Same No. 2.742,379, Same No. 2,739,891, Same No. 3,068,101
No. 3,158.484, No. 3.201,25
No. 3, No. 3,210,191, No. 3,294,5
No. 40, No. 3,415,649, No. 3,441.
No. 413, No. 3,442,654, No. 3,475
, 174, OLS No. 3,545,974, OLS No. 1,942,655, British Patent No. 1,077.317, OLS No. 1,198,450, etc. ``Synthesis of Surfactants and Their Applications'' by Ryohei Oda et al. (Maki Shoten 1964 edition); ``Surface Active Agents'' by A. W. Peiri (Interscience Publication Inc. 19);
1958 edition): "Encyclopedia op Surface Active Agents Volume 2" by T. P. Sisley (Chemical Publishing Company 196)
4th edition): "Surfactant Handbook" 6th edition (Sangyo Tsuriri 10 Co., Ltd., December 20, 1966) and other publications.

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.

The production of the magnetic recording medium according to the present invention includes the magnetic powder,
It is produced by cross-dispersing magnetic paint components such as the fatty acids, fatty acid esters, and binders in a solvent to prepare a magnetic paint, and then applying the obtained magnetic paint onto a support and drying it.

In addition to the above-mentioned magnetic paint components, the magnetic paint may contain additives such as a dispersant, an abrasive, and an antistatic agent, if necessary.

Solvents for magnetic paint or solvents used when applying magnetic paint include acetone, methyl ethyl ketone (MEK),
Ketones such as methyl ing thyl ketone (MIBK) and cyclohexanone; Alcohols such as methanol, ethanol, globanol, and butanol; Ester-based alcohols such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, propyl acetate, and ethylene glycol monoacetate. Ethers such as diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran, and dioxane:
Aromatic hydrocarbons such as benzene, toluene, xylene, etc.: methylene chloride, ethylene chloride, carbon tetrachloride,
Halogenated hydrocarbons such as chloroform and dibenzene can be used.

Further, when mixing the magnetic paint components, the magnetic powder and other magnetic paint components are all simultaneously or individually fed into the 11th kneader. For example, first, the magnetic powder is added to a solution containing a dispersant and kneaded for a predetermined period of time, and then the remaining components are added and mixed continuously to obtain a magnetic paint.

Various kneaders are used for cross-mixing and dispersion. For example, two roll mill, three roll mill, ball mill, pebble mill, sand grinder, Sjegvari
These include attritor, high-speed impeller dispersion machine, high-speed stone mill, high-speed [1%], dispernie goo, high-speed mixer, homogenizer, ultrasonic dispersion machine, etc.

Technologies related to crosstalk and dispersion are described in Chi O Paratong's ``
Paint Flow and Pigment Dispersion (published by John Wiley and Son, 1964)
JT, O, FATTON (Pa1nt Flow an
d Pigment DiIlpersion (19
64 John Wllley and Son)). ``Also, U.S. Patent No. 2,581,414
No. 2,855,156.

Materials for the support include polyesters such as polyethylene terephthalate and polyethylene-2,6-7-talate, polyolefins such as polypropylene, cellulose fatty conductors such as cellulose triacetate and cellulose diacetate, plastics such as polycarbonate, and Co. , A/-sZn and other metals, glass, and various ceramics such as new ceramics such as silicon with aspect ratio and boron nitride.

Support forms include tape, sheet, card, disk,
Any material such as a drum may be used, and various materials are selected as necessary depending on the form.

The thickness of these supports is approximately 3 mm in the case of tape or sheet form.
The thickness is approximately 100μ, preferably 5 to 50μ, and in the case of a disk or card, it is approximately 30 tons to 10μ, and in the case of a drum, it is cylindrical, and the shape is determined depending on the recorder used.

The surface of the support opposite to the side on which the magnetic layer is provided for the purpose of preventing static electricity, preventing transfer, etc. is
k coat ).

Regarding the back coat, for example, US Pat.
No. 804,401, No. 3,293,066, No. 3
, No. 617,378, No. 3,062,676, No. 3,734,772, No. 3.476,596, No. 2,643,084, No. 2,803,556 ,
Same No. 2.887,462, Same No. 2,923,642, Same No. 2.997,451, Same No. 3:007,892
No. 3,041,196, No. 3,115,42
No. 0, No. 3,166,688, etc.

In addition, in order to form a magnetic layer by coating the magnetic paint on the support, gravure roll coating, Meyer bar coating, doctor blade coach ink, reverse roll coating, dirag coating, air knife coating, calendar coating, ski coating, etc. Methods such as spray coating, kiss coating, fantine coating, etc. can be used, and other methods are also possible.Specific explanations of these methods can be found in "Coating Engineering" (March 1970, published by Shokusen Shoten, No. 258). page below)
``Plastic Film - Processing and its Applications'' (
(Published by Gihodo in 1972).

The magnetic layer coated on the support by such a method is
After performing a treatment to orient the magnetic powder according to the present invention in the layer, if necessary, the applied magnetic layer is dried. Further, a magnetic recording medium is manufactured by performing surface smoothing processing and cutting into a desired shape if necessary.

The method for orienting the metal magnetic powder contained in the magnetic layer of the magnetic recording medium according to the present invention is determined depending on the intended use.

[eco effect: (1) Since the magnetic recording medium according to the present invention uses metal magnetic powder in the magnetic layer, the electromagnetic conversion characteristics of the magnetic recording medium do not deteriorate. In addition, (1) the differential thermal curve of magnetic powder is stable up to at least 80°C, so the degree of heat generated by friction between the magnetic head and the magnetic recording medium during recording or reproduction of the magnetic recording medium (magnetic recording medium At an equilibrium temperature of 50° C. to 60° C., the magnetic powder is not oxidized, and furthermore, by simultaneously using a fatty acid and a fatty acid ester, the durability of the margin below the still is excellent due to the synergistic effect with the magnetic powder.

■ The metal magnetic powder whose differential thermal curve does not change up to at least 80°C, and the fatty acids and fatty acid esters that bring out the performance of this magnetic powder by more than 100 degrees Celsius, are used at the same time, resulting in excellent dispersibility, and the resulting magnetic recording medium is A product with excellent durability can be obtained.

■ Monobasic fatty acids with 10 to 18 carbon atoms and fatty acid esters with a total of 15 to 32 carbon atoms contained in the magnetic layer act as lubricants for the magnetic layer, improving the running properties of the magnetic recording medium. Improved.

(2) Since the running properties of the magnetic recording medium have been improved, the frictional heat generated in the magnetic recording medium is reduced, the softening phenomenon of the magnetic layer is reduced, and the wear of the magnetic layer is reduced.

(1) Because the magnetic layer contains a fatty acid having 10 to 18 carbon atoms and a fatty acid ester having a total number of carbon atoms in the range of 15 to 32. There is no "bleeding" (pluming) in the magnetic layer, and the phenomenon of adhesion to the running sliding portion of the magnetic recording medium is eliminated.

[f] Examples: Hereinafter, the specific content of the present invention will be explained with reference to Examples and Comparative Examples. In Examples and Comparative Examples, h in “part”
"L" means "parts by weight."

Examples 1 to 5 and Comparative Examples 1 to 5 ■ Manufacture of magnetic paint: Using Fe-based metal magnetic powder with an A2 content of 3.0 atomic weight % (Fe content of 60 atomic weight % or more), 1
, magnetic powder-containing compositions having the compositions and blending ratios shown in the first and second columns were prepared. In the case where the At content was 3 atoms, the Si content was 0.5 atomic weight % or less.

Note that the atomic ffl amount of At and St was measured using an X-ray microanalyzer (hereinafter referred to as rXMAJ), which will be described later.

Margin below However, among the above Fe-based metal magnetic powders, those with an At content of 3 atomic weight and t% have a property that the differential thermal curve does not change up to 85°C.

Thoroughly mix each of the above magnetic powder-containing compositions in a ball mill,
After dispersing, add 5 parts of Coronate L (polyisocyanate solution manufactured by Nippon Polyurethane Co., Ltd.) and mix uniformly.
Ten types of magnetic paints were obtained. Regarding the obtained 10 kinds of magnetic paints, the magnetic Paint -1, -2, -3, -4
, -5 and comparative magnetic paints -1, -2, -3, -4 and -5.

■ Preparation of magnetic recording media: Next, magnetic paints-1 to 5 and comparative magnetic paints-1 to -
A magnetic field of 2000 Gauss was applied to one side of 10 kinds of polyethylene terephthalate films having a film thickness of 12 μm, each of which had been prepared separately, and was coated to a dry film thickness of 5 μm.

Each of the obtained wide samples was subjected to supercalender treatment, and then slit into 12.65 wm l].
A videotape of the seeds was made. These video tapes were designated as Example Tape 5 and Comparative Example Tape 5, depending on the applied magnetic paints -1 to 5 and Comparative Magnetic Paints -1 to -5, respectively.

Lower margin Comparative Examples 6 to 9 Using Fe-based metal magnetic powder whose differential thermal curve starts changing at 50°C, each composition listed in column i of Table 2 was prepared in columns 2 to 5. A magnetic powder-containing composition was prepared at the blending ratio shown in the column.

Then, using each magnetic powder-containing composition, the same treatment as in Example 1 was carried out to produce a magnetic paint. The obtained magnetic paints were designated as Comparative Magnetic Paints -6 to -9 according to which of the lines 7 to 10 of 141F-1 the monobasic fatty acid/fatty acid ester they contained fell under. Thereafter, using Comparative Magnetic Paints -6 to -9, the same treatments and steps as in Example 1 were carried out to produce a 12.65-inch wide videotape. The obtained tapes were designated as Comparative Example Tapes 6 to 9, respectively, according to the applied magnetic paints (Comparative Magnetic Paints -6 to -9).

Comparative Examples 10 to 13 Table 2,
No. 64t)l''-j4r 10 Comparative magnetic paint-10
~-13 were produced.

Furthermore, using these comparative magnetic paints -1O to -13, the same treatments and steps as in Comparative Examples 6 to 9 were carried out, and 12.65%
A videotape with a width of 11,111 was produced.

The obtained tapes were coated with comparative magnetic paints -10 to -1.
3, each was designated as Comparative Example Tape IO-13.

Examples 6 to 10 and Comparative Examples 14 to 18 The Fe-based metal magnetic powder (At content = 2 atomic weight %) was slowly oxidized and magnetic powder whose differential thermal curve did not change up to 93°C was used. The same compositions as 1 to 5 were prepared at the same blending ratio (Table 1).
3, listed in columns 1 to 11), magnetic powder-containing compositions were prepared.

Next, magnetic paints 6 to 10 were produced by the same treatment as in Examples 1 to 5, and 1j12
．． A videotape of 65■1j was made.

The obtained tapes were coated with magnetic additives-6~
-10, Example tapes 6 to 10 were prepared.

Next, in order to examine the tape performance of Example Tape 10 and Comparative Example Tape 18 obtained in Examples 1 to 10 and Comparative Examples 1 to 18, still durability, saturation magnetization residual rate, and blooming were observed. Table -
The results shown in 4 were obtained. However, these characteristics were expressed according to the following criteria.

■ Methyl durability: Indicates the time in minutes until the reproduction output of a still image decreases by 2 dB.

■ Residual rate of saturation magnetization: The saturation magnetization measured after leaving the sample tape in an atmosphere of 50°C and 90°RH% (relative temperature) for one week corresponds to the saturation magnetization measured before leaving it. Indicated.

■ Blooming Pluming is determined using a microscope.
This was done by observing the tape surface.

Pluming causes the magnetic head to become clogged.
This is undesirable because it may cause a decrease in output due to spacing loss, or the lubricant that oozes out may cause interlayer adhesion and prevent running. Compared to the video head, the magnetic recording medium had good wear resistance even after repeated use, with very little powder falling off or decrease in output.

-1 From the results in Gahaku Table 4, it can be seen that all of the example tapes containing metal magnetic powder, fatty acids, and fatty acid Nisdel whose magnetic layer had a temperature at which the differential thermal curve started changing at 85°C and 93°C had methyl durability, Regarding both saturation magnetism residual rate and blooming, it was found that the conventional metal magnetic powder (temperature at which the differential thermal curve starts to change is 20° to 75°C) and the video tape that did not use fatty acids and fatty acid esters It turned out to be better than that.

Furthermore, aspects regarding the still durability of the videotape and the blending ratio of fatty acid to fatty acid ester added as a lubricant to the magnetic layer are shown in FIGS. 5 and 6. In each figure, the effects of the present invention can be clearly confirmed from the amount of metal magnetic powder added (wt%) vs. still image playback time (6), fatty acid ester/fatty acid addition system] still image playback time ψ). .

[Brief explanation of the drawing]

Figure 1 is an enlarged photograph (electron microscope) showing the surface condition of a conventional metal magnetic powder, and Figure 2 is a differential thermal curve at least 80°C contained in the magnetic layer of the magnetic recording medium of the present invention. Figure 3 is a schematic diagram showing the structure of metal magnetic powder whose outer surface is coated with a polymer compound. Figure 5 is a schematic diagram showing the structure of a metal magnetic powder whose surface has been slowly oxidized.
A characteristic curve diagram showing the relationship between still image playback time (% by weight) and still image playback time,
Figure @6 is a characteristic curve diagram showing the relationship between fatty acid ester/fatty acid in the magnetic layer and still image reproduction time. Patent π Applicant: Konishiroku Photo Industry Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Procedural amendment (voluntary) 1. Indication of the case Relationship with Patent Application No. 111520 of 1988 Patent applicant address: 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name: (127) Konishiroku Photo Industry Co., Ltd. No. 1 U 1 8 Contents of the amendment As shown in the attached sheet. (1) Specification No. 20 Page 11th line 1...ノ・1.f'
100...'' is defined as "...magnetic powder 100...". (2) [...] (inder 1) on page 21, line 6 of the detailed description
00" and "...magnetic powder 100." Written amendment to the above procedures (voluntary) October 14, 1988 Patent Application No. 111520 2, Name of the invention Magnetic recording medium 3, Relationship with the case of the person making the amendment Patent applicant 8, Contents of the amendment Attachment [1. The detailed description of the invention column in the specification is amended as follows. (1) Specification■ "Squareness,..." in the first line of page 2 is changed to "squareness ratio,..." and "...easy to chain..." in line 8 of the same page.
``...'' is changed to ``...easily rusted...''. (2) On page 21, line 7 of the specification, “If..., then AI
)...'' is changed to "If..., then A4 )...". (3) 1...saponin...'' in the fourth line from the bottom of page 21 of the specification shall be changed to "...saponin...". (4) "...Methyl isobutyl ketone..." in Akira III, page 24, line 4 is changed to "...Methyl isobutyl ketone...". (5) “...(Relative temperature)” on page 37, line 14 of the specification cylinder
"..." is changed to "...(relative humidity)...". [2] Figures 5 and 6 of the drawings in "Specification Attachment A" are replaced with the figures shown in (Attachment) K. that's all

Claims (1)

[Claims] Containing, on a support, a metal magnetic powder whose differential thermal curve does not change up to at least 80°C, a fatty acid having 10 to 18 carbon atoms, and a fatty acid ester having a total number of carbon atoms of 15 to 32. A magnetic recording medium with a magnetic layer.