JPS598045B2 - Jikiki Rokutai - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium suitable for magnetic tapes, magnetic disks, etc., and particularly to a magnetic recording medium using ferromagnetic chromium dioxide.

Traditionally, magnetic iron oxide has been exclusively used as a magnetic material for magnetic recording media, but compared to magnetic iron oxide, which is a ferrimagnetic material, chromium dioxide, which is a ferromagnetic analyte, has superior magnetic properties in the following points. It has properties. (■) High saturation magnetization (11) Low electrical resistance 011) Low pressure demagnetization (IV) Directions of crystal anisotropy axis and shape anisotropy axis are close (ri) Change Curie point etc. Therefore, the inventors of the present invention used chromium dioxide as a magnetic material, and as a result of repeated research to obtain an excellent magnetic recording medium,
This has led to the present invention. Magnetic materials for magnetic recording media need to have high coercive force and high saturation magnetization.

CrO, which has high coercive force, can be produced by
A method of thermally decomposing water at high temperature and pressure in the coexistence of water (Special Publication Publication No. 32
-6087, Publication No. 36-18657) A method of heating chromium oxide with a Cr valence of 4 or more and 6 or less under high temperature and high pressure (U.S. Patent No. Z3117093), chromium oxide, chromium hydroxide, etc. A method of heating a compound of trivalent chromium together with an oxidizing agent under high temperature and pressure (Special Publication Publication No. 42
111617), a method for producing CrO from CrO, Ct, a method for obtaining CrO at low pressure, and a method for producing Cr(NO3
)3 and CrO.

A method of manufacturing from a mixture of is known. It is also known to use modifiers such as ruthenium compounds, antimony compounds, tellurium compounds, iron compounds, tin compounds, phosphorus compounds, and tungsten compounds as a method for improving these. (Special Publications No. 36-8839, No. 38-829, No. 4
0-2889, etc.) On the other hand, the residual magnetization of CrO is reversible with respect to temperature changes, and using this property, Cr
A copying method called thermal transfer, in which O2 tape is brought into contact with a master tape having a high Curie point near the Curie point (110 to 125 degrees Celsius) and the signals of the master tape are copied, is disclosed in Japanese Patent Publications Nos. 35-18225 and 43-21273. , No. 43-3234, and other publications.

At this time, the support that constitutes the magnetic edge (for example, PET
, TAC base), binders, plasticizers, and lubricants degrade, contract, and expand when exposed to high temperatures, weakening the mechanical strength of the magnetic recording medium and causing the copied signal to be identical to that of the master tape. It disappears. Therefore, cro2, which has a low Curie point, is required as a slave tape for thermal transfer. Examples of modifiers that change the Curie point of CrO include Fe, Ru, and their compounds that raise the Curie point, and S, P, F, V, Mn, -Ni, and their compounds that lower the Curie point. compounds are known.

Regarding these, for example, Japanese Patent Publications No. 36-8839, No. 38-829, No. 38-18188, No. 47-57
No. 39, No. 48-21874, No. 49-9360,
Publications such as JP-A-48-74500, JP-A-48-40692, JP-A-49-18793, JP-A-48-65500, U.S. Patent No. 3034988 and French Patent No. 21
It is described in the specification of No. 08364. Therefore, CrO has high coercive force, high saturation magnetization, and low single point.
As a result of repeated research to provide 2, it was found that CrO2 obtained by using at least one of Te and Te compounds in combination with at least one of CO and CO compounds as a modifier unexpectedly showed a temperature of 10°C. It has been found that it is suitable as a magnetic material for a CrO2 tape for thermal transfer because it has a temperature of ~21°C, high coercive force, and high saturation magnetization.Based on this knowledge, the present invention was completed.

That is, the present invention provides a magnetic recording material in which a magnetic layer mainly composed of ferromagnetic fine powder and a binder is provided on a substrate, wherein the ferromagnetic material is chromium dioxide modified with Te and CO. This is related to recording media. CrO2 modified with Te and CO of the present invention is produced by adding and mixing at least one of Te and Te compounds and at least one of CO and CO compounds to chromium oxide whose chromium valence is 4 or more. It is obtained by thermally decomposing this mixture in an autoclave at 300 to 500°C in the presence of water.

Water is added in a range of 0.01 to 100 parts per part of the mixture, but too much water is not preferred because the pressure inside the container becomes too high during thermal decomposition. Since the Te and CO components added at the time of blending the three raw materials remain in the finally obtained chromium dioxide, the content of Te and CO can be easily controlled at the time of blending the raw materials. Those used as Te components are Te alone, Te and Te compounds, and Te compounds include TeO2, H6TeO6, Te
Any material containing Te such as Ct4 or TeBr4 may be used.

What is used as the CO component is CO alone and CO compounds, and CO SO4.7H20 is the CO compound.
,C0(NO3)2・6H20,C0Ct2・6H20
,C00,C0,04,C0(CH3COO),・4H
Any material containing CO such as 20, C0(0H)2 may be used. These Te or Te compounds, CO or C
When mixing an O compound and a chromium oxide having a valence of 4 or more, it is preferable to mix them by mechanically crushing them.

Pulverizers used for mechanical grinding include ball mills, vibration mills, impact mills, roll mills, rod mills, cutter mills, and mortars, and wet grinding is particularly effective. Also, when using water-soluble salts as Te compounds and CO compounds, make a solution of them and make a solution with a valence of 4.
It is best to mix it with the above chromium oxides. The magnetic powder mainly composed of chromium dioxide used in the present invention is Te and C.
Contains O, preferably 0.005 to 10 atom % Te (!: 0.01 to 10 atom % CO, more preferably 0.05 to 5.0 atom % Te (!) !
: Contains 10.05 to 5.0 at% of CO.

The CrO2 modified with Te (5C0) of the present invention has high saturation magnetization and coercive force, so it is suitable as a magnetic material for magnetic recording media.In particular, its low single point makes it suitable for use as a magnetic material for slave tapes in thermomagnetic recording. It is suitable as a material and can be used for magnetic tapes, drums, magnetic sheets, etc.

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

Regarding the manufacturing method of magnetic paint, see Special Publication No. 43-186, 47.
-28043, 47-28045, 47-2804
It is described in detail in publications such as No. 6, No. 47-28048, and No. 47-31445.

The magnetic paints described in these documents mainly contain ferromagnetic powder, binder, and coating solvent, and may also contain additives such as dispersants, lubricants, abrasives, and antistatic agents.
As the binder used, conventionally known thermoplastic resins, thermosetting resins, reactive resins, and mixtures thereof are used.

As a thermoplastic resin, the softening temperature is 150°C or less, the average molecular weight is 10,000 to 200,000, and the degree of polymerization is about 200.
~2000, such as vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride copolymer, vinyl chloride acrylonitrile copolymer, acrylic acid ester acrylonitrile copolymer, acrylic acid ester vinylidene chloride copolymer, acrylic acid Ester styrene copolymer, methacrylic acid ester acrylonitrile copolymer, methacrylic acid ester vinylidene chloride copolymer, methacrylic acid ester styrene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride acrylonitrile copolymer, butadiene acrylonitrile copolymer Coalescence, polyamide resin, polyvinyl butyral, cellulose derivative (
Cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), styrene-butadiene copolymer, polyester resin, chlorovinyl ether acrylate copolymer, amino resin, various synthetic rubber-based heat Plastic resins, mixtures thereof, etc. are used.

Examples of these resins are given in Japanese Patent Publication No. 37-6877, 39-
No. 12528, No. 39-19282, No. 40-5349, No. 40-20907, No. 41-9463, 41-14
No. 059, No. 41-16985, No. 42-6428, 4
No. 2-11621, No. 43-4623, No. 43-1520
No. 6, No. 44-2889, No. 44-17947, 44-
No. 18232, No. 45-14020, No. 45-14500
No. 47-18573, No. 47-22063, No. 47-22064, No. 47-22068, No. 47-22069
No. 47-22070, No. 4827886, U.S. Patent No. 3144352: U.S. Patent No. 3419420: U.S. Patent No. 34
No. 99789: Described in the specification of No. 3713887.

As a thermosetting resin or a reactive resin, it has a molecular weight of 200,000 or less in the form of a coating solution, and when heated after coating and drying, the molecular weight becomes infinite due to reactions such as condensation and addition. Also, among these resins, those that do not soften or melt before the resin is thermally decomposed are preferred. Specifically, for example, phenolic resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin,
Alkyd resin, silicone resin, acrylic reactive resin,
Epoxy-polyamide resins, mixtures of high molecular weight polyester resins and isocyanate prepolymers, mixtures of methacrylate copolymers and diisocyanate prepolymers,
These include mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, mixtures of low molecular weight glycols/high molecular weight diols/triphenylmethane triisocyanates, polyamine resins, and mixtures thereof. Examples of these resins are given in Japanese Patent Publication No. 39-8103, 4.
No. 0-9779, No. 41-7192, No. 41-8016, No. 41-14275, No. 42-18179, 43-1
No. 2081, No. 44-28023, No. 45-14501, No. 45-24902, No. 46-13103, No. 47-2
No. 2065, No. 47-22066, No. 47-22067, No. 47-22072, No. 47-22073, 47-2
No. 8045, No. 47-28046, No. 47-28922, U.S. Pat. No. 3,144,353, U.S. Pat. No. 3,320,090
No.: No. 3437510: No. 3597273: No. 37
No. 81210: 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 to 400 parts by weight, preferably 30 to 200 parts by weight, per 100 parts by weight of the ferromagnetic powder. In addition to the above-mentioned binder and fine ferromagnetic powder, additives such as a dispersant, a lubricant, an abrasive, and an antistatic agent may be added to the magnetic recording layer.

Dispersants include chifurylic acid, chipurinic acid, lauric acid,
Fatty acids with 12 to 18 carbon atoms (R, COOH
．． Rl (alkyl group having 11 to 17 carbon atoms): metal soap consisting of the alkali metals (Li, Na, K, etc.) or alkaline earth metals (Mg, Ca, Ba) of the above fatty acids; lecithin, etc. are used.

In addition, higher alcohols having 12 or more carbon atoms and sulfuric esters may also be used. These dispersants are added in the range of 1 to 20 parts by weight per 100 parts by weight of the binder. Examples of lubricants include silicone oil, graphite, molybdenum disulfide, tungsten disulfide, and those having 12 to 16 carbon atoms. Monobasic fatty acids and carbon numbers 3-12-
fatty acid esters consisting of a monohydric alcohol, fatty acid esters consisting of a monobasic fatty acid with 17 or more carbon atoms and a monohydric alcohol with a total carbon number of 21 to 23 carbon atoms, etc. can be used.

These lubricants are used in amounts of 0.2 to 100 parts by weight of binder.
It is added in an amount of 20 parts by weight. Regarding these, the specifications of Japanese Patent Publication No. 43-23889, Japanese Patent Application No. 42-28647, Japanese Patent Application No. 43-181543, U.S. Patent No. 3, etc.
No. 470021, No. 3492235: No. 349741
No. 1: No. 3523086: No. 3625760: No. 3
No. 630772: No. 3634253: No. 364253
No. 9: 3687725 Specification: "IBMTechn
icalDisclOsureBulletin'20
1.9 Black 7, Page 779 (December 1966): "ELEKTRONIK" 1961, Ni 12, Page
38O etc.

Commonly used abrasive materials include fused alumina,
silicon carbide chromium oxide, corundum, artificial corundum,
Diamonds, synthetic diamonds, garnet, emery stones (main ingredients: corundum and magnetite), etc. are used. These abrasives have an average particle diameter of 0.05 to 5 .mu.m, particularly preferably 0.1 to 2 .mu.m. These abrasives are added in an amount of 7 to 20 parts by weight based on 100 parts by weight of the binder. Regarding these, special application
No. 26749, U.S. Pat. No. 3,007,807:3
No. 041196: No. 3293066: No. 363091
No. 0, No. 3687725: British Patent No. 1145349
No.: West German Patent (DT-PS) No. 853211. Natural surfactants such as saponin as antistatic agents: Nonionic surfactants such as alkylene oxide, glycerin, and glycidol: higher alkylamines, quaternary ammonium salts, pyridine and other heterocycles, phosphoniums or sulfoniums Cationic surfactants such as carboxylic acid, sulfonic acid, phosphoric acid, sulfuric acid ester group, anionic surfactant containing acidic groups such as phosphoric ester group: amino acids, aminosulfonic acids,
Ampholytic activators such as sulfuric acid or phosphoric acid esters of amino alcohols are used. Some examples of surfactant compounds that can be used as antistatic agents are disclosed in U.S. Pat.
No. 623, No. 2240472, No. 2288226,
No. 2676122, No. 2676924, No. 2676
No. 975, No. 2691566, No. 2727860,
No. 2730498, No. 2742379, No. 2739
No. 891, No. 3068101, No. 3158484,
No. 3201253, No. 3210191, No. 3294
No. 540, No. 3415649, No. 3441413,
No. 3442654, No. 3475174, No. 3545
No. 974, West German Patent Publication (0LS) No. 194266
No. 5, British Patent No. 1077317, British Patent No. 1198450
Including the specification etc., Ryohei Oda et al. [Synthesis of surfactants and their applications] (Maki Shoten 1964 edition): A. W. “Surf S Active Agents” by Bayley (Interscience Publications Inc. 19)
1958 Saka): T. P. “Encyclopedia of Surf S Active Agents,” by I. Sisli, vol.
Volume” (Chemical Publishing Company, 1964 edition)
: Described in books such as "Surfactant Handbook" 6th edition (Sangyo Tosho Co., Ltd., December 20, 1960).

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 fractionation, improving magnetic properties, improving lubricity, and as coating aids. To form the magnetic recording layer, the above-mentioned composition is dissolved in an organic solvent and applied as a coating solution onto a support.

The thickness of the support is about 5 to 50 ttm, preferably 10 to 4 ttm.
The thickness is preferably about 0 μm, and materials used include polyesters such as polyethylene phthalate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, and polycarbonate. The above-mentioned support has a so-called back coat (Ba-coat) on the side opposite to the side on which the magnetic layer is provided for the purpose of preventing static electricity and preventing transfer.
ckcOat).

Regarding back coats, for example, U.S. Patent No. 28044
No. 01, No. 3293066, No. 3617378, No. 3062676, No. 3734772, No. 34765
No. 96, No. 2643048, No. 2803556, No. 2887462, No. 2923642, No. 29974
No. 51, No. 3007892, No. 3041196, No. 3115420, No. 3166688, etc.

Further, the support may be in any form such as a tape, sheet, card, disk, or drum, and various materials may be selected as necessary depending on the form. Methods for applying the magnetic recording layer onto the support include air doctor coating, plaid coating, air knife coating, squeeze coating, impregnation coating, reverse roll coating, transfer roll coating, gravure coating, scratch coating, cast coating,
Spray coating, etc. can be used, and other methods are also possible, and detailed explanations of these methods are given in [Coating Engineering], pages 253 to 277, published by Asakura Shoten (published on March 20, 1972). . Organic solvents used during coating include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohols such as methanol, ethanol, propanol, and butanol; methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and acetic acid. Ester systems such as glycol and monoethyl ether: Glycol ether systems such as ether, glycol dimethyl ether, glycol monoethyl ether, and dioxane: Tar systems (aromatic hydrocarbons) such as benzene, toluene, and xylene: Methylene chloride, ethylene chloride, and Chlorinated hydrocarbons such as carbon chloride, chloroform, ethylene chlorohydrin, and dichlorobenzene can be used.

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

Further, the magnetic recording body of the present invention is manufactured by subjecting it to surface smoothing processing and cutting it into a desired shape, if necessary. In this case, the orientation magnetic field is approximately 500 to 2000 AC or DC.
Gauss, and the drying temperature is about 50 to 100℃.
Drying time is about 3 to 10 minutes.

Example 1 The following raw materials A to G were weighed, thoroughly mixed, water was added in a 1 ton beaker, and the mixture was further mixed.

Thereafter, A-G was placed in a 50 t autoclave, heated to 350°C at a rate of 60°C/hour in an electric furnace, and maintained at this temperature for 3 hours. After cooling, the sample was taken out from the container, washed with water, and dried. The magnetic properties of the sample thus obtained are shown in Table 1 together with the composition of the raw materials. coercive force,
Saturation magnetization was measured using a vibrating sample magnetometer (VSM-, manufactured by Toei Kogyo)
The measurement was performed using a magnetic field of 50,000 e. Further, the single point of Kyuri was determined from the temperature change of residual magnetization using VSM-, with the external magnetic field set to zero after saturation magnetization. Example 2Cr0
3850f! 6g of TeO was added to the mixture and thoroughly mixed to make 9 types of samples, placed in a 1t glass beaker, and then COS
O4.7H20 and water were added in the composition A-1 and mixed thoroughly.

After that, these were placed in a 50t autoclave,
The temperature was raised to 350°C at a heating rate of 60°C/hour in an external electric furnace, and maintained at 350°C for 3 hours. After cooling, the sample was taken out from the container, washed with water, and dried. Table 2 shows the magnetic properties of the sample thus obtained and the composition of the raw material. The magnetic properties were measured in the same manner as in Example 1. The relationship between the amount of CO and the magnetic properties is shown in the attached diagram, in which curve 1 shows the relationship with a single point, curve 22 shows the relationship with coercive force, and curve 3 shows the relationship with saturation magnetization.

Example 3 1-A, l-E, l-F, 2-A, obtained in Examples 1 and 2
2-E, 2-H, 300 parts of each of the six types of chromium dioxide, mixed thoroughly in a ball mill, and 20 parts of Dismodule L-75 (trade name, polyisocyanate compound manufactured by Bayer) were mixed. In addition, they were uniformly mixed and dispersed to form a magnetic paint.

This paint was applied to a PET base (25 μm thick) with a dry thickness of 10 μm.
It was coated so as to have a diameter of μ, oriented in a magnetic field at 10,000 e, dried, and slit. The B-H characteristics of the thus obtained magnetic tape were measured using VSM-, and a single point was measured using the same method as for the powder.

The results obtained are shown in Table 3. From the results in Table 3, it can be seen that there is only a slight change in the CrO used as a raw material and the curve point of the obtained magnetic tape.

Furthermore, there is no difference in Br/Bm compared to the comparative example 1-F (CrO2 modified only with Te), and it can be said that it is an excellent magnetic tape. The following can be said from the above examples.

The Tc of CrO2 not modified with CO is 116-120 DEG C., as known from Example 1-F, literature values.
CrO2 modified with CO is lower than this value, with a maximum of 21°C lower. Also, when denatured by CO only (
1-E) and when modified with Te, CO (1-B, l-
Comparing D), T is higher when modified with Te and CO.
eThe amount of decrease is large. From the results of 1-E, CO alone causes CrO
Even if 2 is modified, Tc seems to be lowered, but the coercive force is completely insufficient for use as a magnetic recording medium.

On the other hand, those modified with Te and CO have sufficient characteristics to be used as magnetic recording media. The results of Example 2 show that even if the content of CO is minute, it significantly lowers Tc. Especially CO from 0.05 to 5.0
It can be seen that CrO containing atomic percent is extremely suitable for use in magnetic recording media in both coercive force and saturation magnetization. In addition to the magnetic recording material of the present invention having characteristics equal to or better than those of a magnetic recording material using ordinary CrO,
Because of its low point, when used as a slave tape during thermal transfer, thermal transfer can be performed at low temperatures.
came.

Therefore, the properties of the support, binder, plasticizer, lubricant, etc. were not impaired, and the signals from the master tape were transferred correctly.

[Brief explanation of drawings]

The attached drawings show the relationship between the amount of CO and magnetic properties in the magnetic material of the present invention.

Claims (1)

[Claims] 1. In a magnetic recording body in which a magnetic layer mainly composed of ferromagnetic fine powder and a binder is provided on a substrate, the ferromagnetic material is T
A magnetic recording material characterized in that it is chromium dioxide modified with e and Co.