JPS59217226A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide a medium which has high oxidative stablility and shelf life stability, is highly resistant to wear and lessens the wear of a magnetic head by forming a magnetic layer contg. magnetic powder of a metal having the differential heat curve which is stable at least up to a specific temp. and a polishing agent having a grain size of a specific value or below on a base. CONSTITUTION:A method mainly used to obtain magnetic powder of a metal of which the differential heat curve is stable at least up to 80 deg.C is a method of adding various additives, for example, various elements such as nickel, aluminum, silicon, magnesium, copper, phosphorus, etc. and/or the compd. thereof to the alloy components of the magnetic powder of said metal by a method of incorporation, deposition or the like. The polishing agent is enumerated by generally used materials such as alpha-Al2O3, ZrO2, CeO2, gamma-Al2O3, Si3N4, etc. The polishing agent of <=0.5mu grain size is used and is added in a 2-20pts.wt. range by 100pts.wt. a binder. The magnetic powder of the metal and the polishing agent manufactured in such a way are mixed and dispersed with the binder, solvent, etc. to prepare a magnetic coating which is then applied on a base and is dried. The magnetic layer is thus formed.

Description

[Detailed Description of the Invention] (Al industrial field of application: The present invention relates to a magnetic recording medium, and more specifically, it has ■ excellent oxidation stability and storage stability, and ■ high wear resistance. It is an object of the present invention to provide a magnetic recording medium that has less wear on the magnetic head, provides better still images, and has less noise and an excellent S/N ratio.

[b) Prior art Generally, magnetic recording media include a support made of polyethylene terephthalate or the like in the form of a tape or sheet;
The magnetic powder to be included in the n6° magnetic layer, which is formed by coating a support with magnetic powder and a magnetic paint containing a binder as its main component, has the following characteristics: squareness ratio, saturated magnetization, and coercive force. In this respect, metal magnetic powder is preferable to iron oxide d1 powder. However, in terms of high-temperature recording, if the particle size of the magnetic powder is reduced to 1μ or less, not only will the dispersibility decrease, but also the surface area will increase, so the magnetic powder will be easily oxidized and stored. Stability 8. Still durability decreases.

The reason why metal magnetic powder is so susceptible to oxidation is said to be due to pinholes on the surface of magnetic powder, which are based on the 1-year life cycle inherent to metal magnetic powder.

Furthermore, the magnetic recording medium travels while coming into contact with the magnetic head, guide member, etc. when recording and reproducing information. Especially during playback, it is necessary to reduce the playback output f+%.
Magnetic a) Wt 15 in sliding contact with the magnetic head,
As a result of repeated running, frictional heat is generated, which causes the magnetic layer to wear out and clog the magnetic head.

In order to prevent such abrasion of the magnetic layer, a method is known in which an abrasive is added to the magnetic layer in advance. In terms of improving the wear resistance of the magnetic layer and preventing softening, the larger the particle size of the abrasive added, the greater the effect.However, on the other hand, this increases noise and wear of the magnetic head.

In view of these circumstances, the present inventor conducted electron micrographs of the surface state of metal magnetic powder and measured differential thermal curves as a method to investigate the oxidation stability of metal magnetic powder. We learned that there is a close relationship between the surface condition and changes in the differential thermal curve. That is, the surface of the conventionally known metal magnetic powder (metal magnetic powder whose differential thermal curve is stable from 20'O to 70'O) is shown in the electron micrograph (3
In Manbaun, each pine needle-like magnetic powder is a magnetic powder that is relatively smooth and does not change, but the differential thermal curve is 20". It is a metal that is stable at temperatures in the range of 0 to 80°C. When it comes to magnetic powder, its surface is quite rough, as shown in Figure 2, and it is thought that there are fewer pinholes, which are said to be related to the oxidation stability of metal magnetic powder. In order to meet the demands of improving the dust resistance of the magnetic layer and minimizing wear on the magnetic head, it is possible to achieve this goal by reducing the particle size of the abrasive added to the magnetic layer to 0.5μ or less. I was able to carry out the present invention by knowing that it is possible to do so.

(c) Object of the invention: That is, the present invention has excellent aging stability and storage stability, and is also highly wear resistant, with little wear on the magnetic head and excellent performance even after repeated use. The purpose of the present invention is to provide a magnetic recording medium that provides still images and has less noise.

(d) Structure of the invention: The object of the present invention is to coat a metal magnetic powder having a stable differential thermal curve up to at least 80゛0 and a particle size of 0 on a support.
．． This is achieved by forming a magnetic layer with an abrasive of 5μ or less.21. Ru.

Examples of metal magnetic powders that can be used in the magnetic layer of the magnetic recording medium according to the present invention include Fe-Ni-Co alloy, Fe-Mn-Zn alloy, Fe-Co-N
i-P alloy, Fe-Ni-Zn alloy, JIle-N
i-Cr-P alloy, Fe-Co-Ni-Cr alloy, p'e-Co P alloy, Fe-Ni alloy, Fe
-Ni -Mn alloy, Go-Ni alloy, Co-Ni
P alloy, Fe = AI alloy, Fe -Mn -Zn
Alloy, Ii'e-AI-P alloy etc. Fe, N15C.

Examples include metal magnetic powders that produce .

There are methods for obtaining metal magnetic powder (hereinafter referred to as "magnetic powder") 8 whose differential thermal surface 1 is stable up to at least 80 DEG C., as described in C and -F.

(As shown in the ilJa diagram, the outer surface of the metal magnetic powder is coated with a thermally stable polymer compound ζ such as polyamide resin)2
How to cover with.

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

(3) Various additions may be made to the alloy components of the metal magnetic powder, such as Nikkenope aluminum, silicon, magnesium,
This is a method in which glaze ingredients such as copper and phosphorus and/or compounds thereof are added by a method such as 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 as a general rule, (3)
It is preferable that the magnetic powder obtained by the method (11) and (2) is used as the basis, and if necessary, it is preferable to supplementally employ one or both of the methods (11 and (2)). That is, ( For magnetic powder obtained by method L), metal magnetic powder (magnetic material) per unit volume of magnetic powder
As a result, the amount of magnetization per unit volume of the magnetic layer is smaller than that when uncoated metal magnetic powder is used. For example, in a coated magnetic recording medium in which the magnetic layer is mainly formed of magnetic powder and a binder, the thermal stability (or oxidation stability) of the metal magnetic powder to be contained in the magnetic layer can be improved by the method described in 111 above. When this is realized, the substantial filling rate of the magnetic material in the magnetic layer becomes low, which is not preferable for a recording medium that performs high-density recording. In addition, the magnetic powder obtained by the method of
This method requires the use of special dispersants, etc., and has the drawback of complicating the manufacturing process.

The magnetic powder obtained by method (2) also has the same drawbacks as the magnetic powder obtained by method (11). In this case, the volume of the non-oxidized portion that contributes to magnetization is smaller than the volume of the magnetic powder, as in case (1), so the actual filling rate of the magnetic material in the magnetic layer decreases. The magnetic powder used in the magnetic layer of the magnetic recording medium of the invention is thermally stable (or oxidatively stable).
It is preferable that it has (1
) or (2), or this 1. It is preferable to use a combination of these methods.

In addition, it is also possible to use the methods described in (zl and (2) above) or other methods, 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 pinholes of the magnetic powder. It is also possible to immerse it in the clear liquid of (jj).
1-1N or the method described in [Work] above may form a thin film on the surface of the magnetic powder, but the thermal stability may not be sufficient. ), this can be chemically or physically reacted to form a thermally or oxidatively stable magnetic powder. At least the magnetic powder of the present invention is modified so that the metal magnetic powder is stable against heat or oxidation up to at least 80°C to the extent that the magnetic properties are not impaired for at least one month. 80
It is a metal magnetic powder that has a stable differential thermal curve down to -0.

Among the above-mentioned methods (3) and other methods, the method (3), which is used as the standard, will be explained in detail.

Each metal element and/or compound is added to the metal component of the metal magnetic powder (here, the metal component mainly means J components other than carbon, hydrogen, oxygen, etc. that are not detected by an X-ray microanalyzer). In the method (3) of adding , preferred additives include aluminum, silicon, nickel-46, and compounds thereof.

When the additive consists of AJ and/or its compounds
: The amount added is A/A in the metal components of the metal magnetic powder.
Atom (for example, AJ2 if the additive is AI!203)
The proportion of atomic M in all metal components is 0.5 to 5.
The range is 20 atomic weight %, and particularly preferred is 1 to 20% by atomic weight.
The range is 20 atoms, ili, and quantity ti. Ar atom is 05
If the amount is less than atomic weight, the thermal or oxidative stability of the resulting metal powder will not be sufficient, and the storage stability and durability of magnetic recording media made using magnetic powder will deteriorate. It will be enough.

In addition, when using the St element and/or its compound as an additive, the metal component part of the metal magnetic powder [ A/? , St.

StFe, Co+Ni+na, 11f, CtzP,
The weight ratio occupied by Si atoms is 1% by weight or less, preferably 0.5M or less, and in some cases 0.1%.
It may be less than □ If Si is outside this range, it may be difficult to modify the magnetic powder.

Furthermore, when containing N1 element and/or its compound as an additive, the upper limit is 30 atoms M from the viewpoint of magnetic properties.
It is desirable that the content is t% or less, preferably 20 atomic weight or less.

A differential thermal curve measures the temperature difference between a thermally stable reference material such as alumina or quartz and a sample when the two are heated at a constant rate. It is described in detail in Kanawa's ``New Experimental Chemistry Course 2, Basic Technology''.

The magnetic housing layer of the magnetic recording medium according to the present invention (a material commonly used as an abrasive to which α-Aj?2 can be added)
03, 5t02, TiO2, Cr2O3, 1r02
, Cos2, γ-A/203, Si3N4, BN,
A/! N etc. are 4mt difficult. Koi 1. These abrasives have a particle size of 0.5 μm or less, and those with a particle size of 0.3 μm or less are particularly preferred. These abrasives were added at a strain of 2 to 20 parts by weight to 100 parts by weight of BAINKU. 1. Ru. Regarding the various dynamics of these abrasives other than the particle size, please refer to Japanese Patent Application Laid-Open No. 1155-1983.
Publication No. 10, U.S. Patent No. 3,007,807, U.S. Patent No. 3,041,196, U.S. Patent No. 3,687.725
See also British Patent No. 1+145+349, West German Patent No. 853.211, Specification 4'Ff.

In the present invention, it is important that the particle size of the abrasive is 0.5μ or less, and as shown in Figures 3, 4, and 5,
By combining an abrasive with a particle size of 0.5μ or less and metal magnetic powder whose differential thermal curve remains unchanged up to 80°C, the S/N ratio and head wear are lower than conventional magnetic recording media. , 71 is also improved. In other words, by using an abrasive with a diameter of 0.5μ or less, the wear of the magnetic head is significantly reduced, extending the life of the head, and the S/N ratio of the recording medium is also improved by using an abrasive with a diameter of 0.5μ or less. Significantly improved. Due to the stability of magnetic materials, the still life of the recording medium is significantly improved. At the same time, the contradictory characteristics of improving the still life and reducing head wear can be solved simultaneously, and the S/ The improvement of recording characteristics called N ratio was something that had never been done before.
This will significantly contribute to the improvement of magnetic recording.

The magnetic recording medium according to the present invention coats a magnetic coating material on a support by mixing and dispersing a magnetic powder-containing composition comprising magnetic powder, a binder, a solvent, the abrasive agent, and other components added as necessary. and dry to form a magnetic layer.

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

Thermoplastic resins with a softening temperature of 150°O or less, an average molecular weight of 10,000 to 200,000, and a degree of polymerization of about 200 to 2,000, such as vinyl chloride.
Divinyl copolymer, vinyl chloride-vinyritine chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acryloni copolymer, acrylic ester-vinyritine chloride copolymer, methacrylic ester - Vinyritine chloride copolymer, methacrylic acid ester-ethylene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-butadiene copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (
Cellulose acetate phthylate J2 Cellulose diacetate, cellulose triacetate, cellulose bromine, nitrocellulose, etc.], styrene-butadiene copolymer, polyester resin, chlorovinyether-acrylic acid ester copolymer, amino η (fat, Mixtures of various synthetic rubber-based thermoplastic resins and the like are used.

The resins of Koit et al.
No. 3, No. 41-14059, No. 41-16985, No. 42-6428, No. 42-11621, No. 43
-4623-, 43-15206, 44-28
No. 89, No. 44-17947, No. 44-18232, No. 45-14020, No. 45-14500, No. 4
No. 7-18573, No. 47-22063, No. 47-2
No. 2064, No. 47-22068, No. 47-2206
No. 9, No. 47-22070, No. 448-27886, U.S. Patent No. 3, 144.

No. 352, Specification No. 3,419,420, No. 3.
No. 499°789 and No. 3,7J3,887.

t as a thermosetting resin or reactive resin in the state of a coating liquid.
The molecular weight may be from o,ooo to 200,000,
After coating and drying, the molecular weight may become infinite due to reactions such as condensation and addition. Moreover, among these resins, those that do not soften or melt before the resin is thermally decomposed are preferable. Specifically, examples include phenol 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. mixtures of polymers and diisocyanate polymers, mixtures of polyester polyols and polysocyanates, urea formaldehyde resins, mixtures of low molecular weight glycols/high molecular weight diols/triphenylmethane triisocyanates, polyamine resins and mixtures thereof, etc. 〇These resins are listed in Japanese Patent Publication No. 41-8016, No. 41-1
No. 4275, No. 42-18179, No. 43-1208
No. 1, No. 44-28023, No. 4'5-14501, No. 45-24902, No. 46-13103, No. 4
No. 7-22067, No. 47-22072, 1; J47
-22073, 4-r-2so45@, 47-2
No. 8048, lr>447-28922, publication specification, U.S. Patent No. 3,144,353, U.S. Pat.
No. 0,090, No. 3,437,510, No. 3,5
No. 97,273, same No. 3. '781,210, same No. 3
, No. 781.211, the statement is included in the subscript.

'Electron beam irradiation-curable resins include unsaturated prepolymers such as maleic anhydride type, urethane acrylic type, epoxy acrylic type, polyester acrylic type, polyester acrylic type, polyurethane acrylic type, polyamide acrylic tights, etc. Examples of functional monomers include needle acrylic type, urethane acrylic type, epoxy acrylic type, phosphoric acid ester acrylic type, aryl type, and hydrocarbon type.

The binder may be used alone or in combination, and other additives may be added if necessary.

The mixing ratio of the magnetic powder and the binder is 5 to 200 m, preferably 10 to 100 parts by weight, per 100 parts by weight of the magnetic powder. If the amount of O binder mixed is too large, When used as a magnetic recording medium, the recording density decreases, and if it is too low, the strength of the magnetic layer becomes weak, resulting in undesirable situations such as decreased durability and discoloration.

Additionally, various hardening agents can be added to the magnetic layer to improve the durability of the magnetic recording medium. for example,
Incyanate etc. can be used. Aromatic incyanates that can be used are, for example, tolylene diisocyanate ('l''DIJ, 4,41-diphenylmethane diisocyanate (D, 1D11, xylylene diisocyanate tXI) Il, meta-xylylene diisocyanate (M ,

Specifically, Sumitomo Bayer urethane (manufactured by Kawasha)
:Product name Sumiseal T80, Sumiseal 44S, Sumiseal PF, Sumiseal L
1 Desmodu kT65, 15, R1 RF, IL, SL; 3008, 500; products manufactured by Mitsui Nisseki Urethane Co., Ltd. rNDIJ, rTODIJ; Desmodule products manufactured by Nippon Polyurethane Co., Ltd. T 100. Millionate MR
, MT, Koroi, Tom; PAPI-135, manufactured by Kasei Upjohn Co., Ltd., TI) I65, 80. Same 100
, Isonate 125M, and Isonate 143L.

On the other hand, examples of aliphatic isocyanates include hexamethylene diisocyanate IHMDI), lysine incyanate, and trimethylhexamethylene diisocyanate;-)(
Examples include TMDII and adducts of these incyanates and active hydrogen compounds. Among the aliphatic incyanates 6 and adducts of these incyanates and active hydrogen compounds, those having a molecular weight in the range of 100 to 3,000 are preferred.

On the other hand, among the aliphatic isocyanates, non-alicyclic incyanates and adducts of monochloride compounds and active hydrogen compounds are preferred.

Specifically, for example, Sumidur N1 Desmodur Z4273 manufactured by Sumitomo Bayer Urethane Co., Ltd., Durane 50M, 24A-Zoo, and 24A- manufactured by Asahi Kasei Co., Ltd.
90CX, manufactured by Nippon Polyurethane Co., Ltd. Coronet) HL,
There are also 1' MDI products made by Hüls.

Also, alicyclic a) among aliphatic incyanates, 4.
4'-methylenebis(cyclohexyl isocyanate J
Ls formula; OCN % CH2Q NCO), inphorone diincyanate, and adducts of its active hydrogen compounds.

Specifically, the products manufactured by Hüls Kagaku Co., Ltd. (I) 1.
) IJ, IPDI-T1890, IPDI-I (2921
, same 11J, 065, etc.

The magnetic recording medium of the present invention is prepared by mixing and dispersing the magnetic powder, the binder and various additives with an organic bath medium to prepare a magnetic coating material 8, and adding the aromatic isocyanate and aliphatic incyanate. This is coated on a support (for example, a polyester film), dried if necessary, and then
Ru.

The isocyanate ratio is 1-10 to the binder.
Add/add 0 weight factor. If it is less than 1, the hardening of the magnetic layer tends to be insufficient, and if it is more than 100, (convexity)→
Even if it hardens, it tends to become "sticky". In order to obtain a more preferable magnetic layer, incyanate is preferably added in an amount of 5 to 30 times the binder.

Examples include an adduct of incyanate and an active hydrogen compound, an adduct of C, a diisocyanate and a trivalent polyol, or a pentamer of diisocyanate. Specific examples of these include 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 tolylene diisocyanate. 2 mole 5'
:It form, deoxidized form obtained by reacting 3 moles of hexamethylene diisocyanate with 1 mole of water, etc., and these are easily obtained industrially.

゛ In addition to the above-mentioned magnetic powder, binder, and curing agent, additives such as a dispersant, an abrasive, and an anti-rust agent may also be added to the magnetic layer. , &) phosphoric acid ester, amine compound, alkyl)ray-F /L/ 7:r
-), fatty acid amide, higher alcohol oxide, sulfocono1 screening, sulfo=1no・ri1,
Quester, known surfactants, etc. It et al.'s soil strength S is present, and also negative and Isoki (e.g. -COO) I,
It is possible to use a salt of a polymeric dispersant having -PO3H).

Only one type of dispersant may be used, or two or more types of 1 may be used in combination. This, IL Rinomin 1
The sheet angle 1j is added within the range of 1 to 20th power 7+3: ijμ to 100 parts by weight of the binder. Regarding the dispersant, C is Special Publication No. 41 i8U6
No. 4shi, No. 49-184405, No. 52-7081J
No. 57-1048 and Japanese Patent Application Laid-Open No. 57-33434, the specifications are disclosed in U.S. Pat.
1470.02Lj No. 4, the proviso etc. can be referred to.

As a lubricant, silicone oil, carbon black, graphite, carbon black graft polymer,
Molybdenum disulfide, tungsten disulfide, 1 carbon atom
These can also be used for fatty acid esters (so-called waxes) consisting of monobasic fatty acids of 2 to 16 and monohydric alcohols having a total number of carbon atoms of 25 to 23. The lubricant is added in an amount of 0.2 to 20 parts by weight based on 100 parts by weight of the binder. Coil
, et al. 1゛Imo Kosho No. 43-23889, No. 43
-81543 publication specification, U.S. Patent No. 3, 470
, No. 021, No. 3, 492,235, No. 3,
No. 497,411, same No. 3.

523, No. 086, same day! No. 31625.720, No. 3, 630.

No. 772, No. 3.634.253, No. 3, 6
30, No. 772, same No. 3, 634, 253
No. 3,642,539, No. 3,687.72
5-1 specifications, IBM Technical Disclosure Plutan Magazine Vol. 9, No. 7, page 779 (December 3, 1966)
l Disclosure Bulletin vol.
．． 9 lA, 9 r Page 779 (1966
December: Electronics Magazine No. 12, page 380 (1965) (ELEKTR
ONIK.

A 1 2, Page 380, 1961
Dielectric powder such as graphite, carbon black, tin oxide-antimony oxide compound, tin oxide-titanium oxide-antimony oxide compound, carbon black graft polymer, etc. as an antistatic agent if necessary as described in 1. Natural surfactants such as saponins: Nonionic surfactants such as alkylene oxides, glycerols, and glycidols; Cationic surfactants such as higher alkylamines, quaternary pyridines, other heterocycles, phosphoniums, and sulfoniums. 2. Karbonba,
Anionic surfactants such as amino acids containing hostile groups such as sulfonic acid, phosphoric acid, sulfuric acid ester groups, and phosphoric ester groups, amino sulfonic acids, and amphoteric surfactants such as phosphoric acid or phosphoric acid esters of amino alcohols are used. These surface active agents that can be used as antistatic agents are
No. 48 specification, U.S. Patent No. 2.

No. 271, 623, No. 2.240.472, No. 2,288.

No. 226, No. 2,676.924, No. 2.676
．． No. 975, No. 2,691.566, i'52,
No. 727,860, No. 2.730,498, No. 2
．． No. 742.379, No. 2.739.891, No. m
No. 3,068,101, No. 3 158.484-, No. 3 + 201 + 253, No. 3 210
．． No. 191, EJ'r 3+ 294 + 540, No. 3,415゜649, No. 3,441,413
No. 3,442.654, No. 3,475,17
No. 4, No. 3,545.974, West German Patent Publication No. 1,942.655, British Patent No. 1.077.317
In addition to the specifications of No. 198,450, etc.
Ryohei Oda et al., “Synthesis of surfactants and their applications” (Kaishoten, 1964 edition): p, w, Bayley, “Surface Active Agent J (Interscience Publication Inc., 1958 edition)
: "Encyclopedia Op 7 Esactive Agents Volume 2" by T. P. Sisley (Chemical Baplish Company 1964 edition) = "
Surfactant Handbook, 6th edition (Sangyo Tosho Co., Ltd., December 20, 1970), etc.

These surfactants may be added alone or in combination. Although these are used as antistatic agents, they are sometimes applied for other purposes such as dispersion, improving magnetic properties, improving lubricity, and as coating aids.

In the present invention, the magnetic layer of the magnetic recording medium in P3 is prepared by cross-dispersing magnetic paint components such as the magnetic powder, the abrasive, and the binder in a solvent, and then supports the obtained magnetic paint. It is made by applying it on the body and drying it.

In addition to the above-mentioned magnetic paint components, the 41Fi paint can optionally contain 61≦additives such as a dispersant, a lubricant, and an antistatic agent.

Solvents for magnetic paint or solvents used when applying magnetic paint include acetone, methyl ethyl ketone IMEKI,
Ketones such as methyl isobutyl ketone (MIBK) and cyclohethisanone; Alcohols such as methanol, ethanol, propatool, butanol; methyl acetate, ethyl acetate, butyl acetate, f[ethyl, propyl acetate, ethylene glycol monoacetate, etc. Ethers such as diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran, dioxane, etc.: benzene, toluene, xylene '4 (7)
Aromatic hydrocarbons: halogenated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, and dichlorobenzene can be used.

In addition, when mixing the magnetic paint components, the magnetic powder and other magnetic paint components are fed into a kneading machine simultaneously or individually one after another.1. Ru. For example, first, the magnetic powder is added to a solution containing a dispersant, and after kneading for a predetermined time, the remaining valley components are added, and the mixture is continued to coat the Mi magnetic paint.

When distributing crosstalk, q! r types of mixers are used. For example, two roll mill, three roll mill, ball mill, pebble mill, sand grinder, Sqegv
These include ari attritor, high speed impeller dispersion machine, high speed stone mill, high speed impact mill, disper niter, 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 (1964, published by John Wiley 7th Edition) J (T, 0. PATT (JN (Paint F)
IOWand Pigment Dispersion
(1964, Jobn Willey & 5on)
It is stated in Also, U.S. Patent No. 2゜581.41
No. 4, gJ2, 855, 15a.

In addition, regarding the manufacturing method of magnetic paint,
No. 46, No. 47-28047, 1uJ47-3144
No. 5-, No. 48-11162, No. 48-21332, and No. 48-33683.

Support materials include polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose tiacetate, plastics such as polycarbonate, and Cu. , A/, Zn and other Φ metals, glass, and various ceramics such as so-called new ceramics (for example, silicon nitride and silicon carbide) can be used.

Support forms include tape, sheet, card, disk,
There is no need for drums, etc., and C is also good, and the form and necessity are 3.
! 2. Various materials are selected accordingly.

The thickness of the support is approximately 3 mm in the case of a tape or sheet.
It is about 100μ, preferably about 5 to 50μ. In the case of a disk or card, the pitch is 30μ to 1°, 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 is coated with a so-called baraf coat lBa for the purpose of preventing banding, preventing transfer, etc.
ck coat) You can also wear it.

Regarding bank coats, for example, U.S. Pat. No. 2.804
．． No. 401, aT3.2c+a, o66, No. 3,
617゜378, same! 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. 2.92: L642, Same No. 2,997,451, Same No. 3゜007, 89
No. 2, No. 3. Otl, No. 196, same m 31041
.

No. 196, No. 3,115,420, J 3r 1
6 +3 r (described in each specification such as No. 588).

In addition, methods for applying magnetic coating materials to form a magnetic layer on a support include gravure roll coating, Meyer bar coating, doctor blade coating, reverse roll coating, tip coating, air knife coating, and calendar coating. Coating, skime coating, kiss coating, fan tin coating! - method can be used, and it is also possible to use other methods. -Processing and its applications-
(published by Gihoto in 1971) is described in detail.

The magnetic paint coated on the support by the above-mentioned coating method is coated after applying an orientation treatment to the magnetic powder in the magnetic layer according to necessity, and then dried. In addition, magnetic recording media are manufactured by subjecting the material to surface smoothing and cutting it into a desired shape.

When orienting the magnetic particles in the magnetic layer, the orientation magnetic field is alternating current or direct current, about 500 to 3,500 Gauss, the drying temperature is about 50 to 100'O, and the drying time is about 3 to 10 About a minute is preferable.

The orientation method of the magnetic powder is determined according to the intended use of the magnetic layer. Methods for orienting magnetic powder are described, for example, in U.S. Patent No. 1.949,840, U.S. Pat.
No. 3.4L6,949, No. 3,473,960, No. 3,681,138, written by Akira Tani, Tokuko Sho 32
-3427, 39-2836, 40-2362
No. 4, No. 40-23625, No. 41-13181-1
It is described in the specifications of each publication such as No. 1 No. 48-13043 and No. 48-39722.

Eel effect: ■ The magnetic recording medium according to the present invention has an
The differential thermal curve is stable up to 0, and there are few pinholes on the surface of the magnetic powder, so it has good oxidation stability.

(2) Therefore, as a magnetic recording medium, there is little change in electromagnetic conversion characteristics over time.

■ Since the grain size of the polishing agent contained in the magnetic layer is small, less than 0.5μ, the abrasion resistance of 11 pads can be adjusted to an appropriate value, improving the durability of the magnetic recording medium and I:L properties. is also good.

■ Also, as mentioned above, since the particle size of the polishing material is small,
It has advantages such as low noise generated in the magnetic recording medium.

(flExample: Hereinafter, specific examples of the present invention will be explained with reference to Examples and Comparative Examples.Example: +3 In the comparison column, "parts" means "parts by weight". shall be taken as a thing.

Example 1.2 ■ Manufacture of magnetic paint 2 AI! The content is soi1zo Ql, 3 atomic claw amount Chu and 4
．． Fe-based metal magnetic powder with diatomic weight ratio (all have Fe content of 60φ or more, and so on).

The differential thermal curves of the magnetic powder are 1'1.83'O and 1'O, respectively.
There is no change from 6 to 95°C. ), Table-1, No.
Ingredients listed in column and 2nd #ilI and sweat distribution ratio 71
) A magnetic powder-containing composition was prepared.

Table-1 ゜ )″g84′ Fitting powder-containing powder-containing composition ′v
After dispersing 1/10 cup of s''7, 5 parts of Coronate L (manufactured by Nippon Polyurethane Co., Ltd., Incyanate: trade name J) was added to produce two types of magnetic paints. The type of metal magnetic powder (A/content is 1.3 atomic weight % or 4.2 atomic weight %), respectively. −
○ ■ Preparation of magnetic recording medium: Next, magnetic paints -1 and -2 were applied to one side of separately prepared polyethylene prephthalate films with a film thickness of 2 μm to a dry film thickness of 5 μm while applying a magnetic field. I painted it to look like this.

Each of the obtained wide samples was subjected to supercalender treatment, and then cut to 12.65, +j''.
Two types of videotapes were made. The type of magnetic coating applied to these two types of tape: 1f1-based paint, -2, according to 21. These tapes were designated as Example Tapes 1 and 2, respectively.

Example 3 Except for using silicon carbide with a particle size of 0.15μ as the abrasive, a magnetic powder-containing composition with the same components and blending ratio as in Example 1 was used, and according to the same treatment and steps, 12.65μ
A m-wide videotape was prepared and this tape was designated as Example Tape-3. Example 4 AI of metal magnetic powder! The surface of magnetic powder with 1.5% inclusion is covered with silicon oxide, and metal magnetic powder whose differential thermal curve does not change up to 85°C17 and particle size 0.3 as abrasive are used.
A videotape with a width of 1.2.65 TB was produced by using a magnetic powder-containing composition having the same components and blending ratio as in the example, and by the same treatment and steps except that μ SiC was used. This tape was designated as Example Tape-4.

Example 5 The surface of magnetic powder with Aj' content of 1.5% was slowly oxidized to produce Fe-based metal magnetic powder whose differential thermal curve did not change up to at least 85°C, and as an abrasive. Particle size()
, 4μ of Cr2O5 was used, a magnetic powder-containing composition having the same components and blending ratio as in Example 1 was used, and the same treatments and steps as in Example 1 were carried out to produce a video tape with a width of 12.65 tym. was created. This tape was designated as Example DEBU 5.

Comparative Examples 1 to 3 ■ Manufacture of magnetic paint; α- particle size of 0.2μ:0.4μ=1.2μ
AI! 203 powder and Fe-based metal magnetic powder whose outer surface was subjected to slow oxidation treatment and whose differential thermal curve does not change up to 50°C were used. A magnetic powder-containing composition having the components and blending ratios listed in the first column and the second column was prepared.

Table 2 5 parts of Coronate L was added to the above magnetic powder-containing silk composition, and thoroughly mixed and dispersed in a ball mill to produce four types of (1; l type paints. , government-owned 4ut abrasive α-A$20.Particle size of powder particles is 0.2.0
In accordance with 4.07.1.2μ, Comparative magnetic paints -1, -2, -3, and -4 were respectively used.

■ Preparation of I-Miki 48 recording medium: Next, magnetic materials -1, -2, -3 and -4 were prepared.
1t, while applying a magnetic field to one side of a separately prepared polyethylene terephthalate film with a thickness of 12μ, dry li! It was coated so that the thickness was 3μ.
Four types of wide width samples were each subjected to supercalender treatment and cut into 12.65 m widths to produce four types of videotapes.

Comparative Example Tapes 1, 2, and 3 were applied to the obtained four types of video tapes according to the types of magnetic paints -1, -2, -3, and -4 applied to one side. And so.

Comparative Example 4 Same treatment as Comparative Example 1, except that 8102 powder with a particle size of 03μ and Fe-based metal magnetic powder whose surface was coated with silicon oxide and whose differential thermal curve changed after 70'Ol were used. A videotape of 12.65 m1 was created.

Comparative Example 5 using the obtained videotape as Comparative Example Cape 4
~6 α-A12 with particle sizes of 0.7 μ and 1.2 μ, respectively
03 powder, the surface is coated with silicon oxide, and Fe-based metal magnetic 8, which shows a change in the differential thermal curve for the first time at 850, is used.
The same treatment as in Comparative Example 1 was applied except that t4 was used, and 2. f! I made one videotape.

α-AI containing these and deotapes in the magnetic layer
! Depending on the particle size of 203 powder 0.7μ and 1.2μ,
These were designated as Comparative Example Tapes 5 and 6, respectively.

Next, the measurement results of the tape performance of Example Capes 1 to 5 and Comparative Example Tapes 1 to 6 obtained by performing the treatments of Examples 1 to 5 and Comparisons 1 and 11 to 6 are shown in the table of Tc. l
Shown below.

Table 1 However, the tape performance in Table 1 is shown in terms of weight, chroma signal carrier-to-noise ratio, still image life, and head wear. "That is, ■ Chroma signal carrier-to-noise ratio: Relative speed of tape: 3.9 m7, Recording current: 4
．． OMEl, z's optimal 4e recording style, recording signal 24.0
Station (z+0.63■1z signal mixing ratio=4.0 MHz
M raw output/2.74 R11 (z playback output = 2dll), the signal was recorded and played back, and the ratio of the day-to-noise of 0.53 Mllz and the playback signal of 0.63 MI (z) was compared. 1 as the reference 10a) ■Still image life: Commercially available Vl (C51 using S method video tape)
A 00% white signal was recorded and reproduced, and the time required for the RF output to decrease by 1 dEI was displayed in minutes on the still image top.

■ Head wear: After using a commercially available VTTS video tape deck,
After 100 hours of playback, the magnetic head was observed using a sharp microscope.
The difference in height of the head surface before and after playback was taken as head wear, and the difference was expressed in μ units.

In addition, the table shows the particle size Cμm of the abrasive particles contained in the magnetic layer of each tape versus the chrominance c, aq, chrominance carrier noise, still image life 1, and head wear amount (μ). Showing the curve: 1. ig3 figure to 5th
Obtain the characteristic curve diagram shown in Figure 1. Ru. However, in Figures 3 to 5, the marks ○, Δ, ・ and Mu indicate that the differential thermal curve is stable up to 93"0, 80'0, 73°0 and 50"0. The characteristics of a magnetic recording medium containing metal magnetic powder and the abrasive in the magnetic layer are shown below.

From the results of characteristic surface blemishes in Table 1 and Figures a↓3 to 5, it is clear that when the particle size of the abrasive particles is larger than 0.5μ, the metal magnetic powder has a stable differential thermal curve up to at least 80℃. In the case of a magnetic recording medium containing a conventional metal magnetic powder whose differential thermal curve does not change up to 50'O, the amount of wear on the magnetic head increases (Fig. 5), but the still life is
Those using metal magnetic powder whose differential thermal curve does not change up to at least 80"0 are the same as conventional metal magnetic powder (73℃,
Compared to the one using Metal Magnetic Powder 1, which has a stable differential thermal curve up to 50"0, it has increased dramatically (Figure 4)
.

Furthermore, as shown in Figure 5, the chroma signal carrier-to-noise ratio decreases rapidly when the particle size of the abrasive becomes larger than 0.5μ. 1 piece in g.

[Brief explanation of drawings]

Figure 1 is an electron micrograph of a metal magnetic powder whose differential heating surface + mJ is stable up to 70-0, and Figure 2 is an electron micrograph of a metal magnetic powder whose differential thermal curve is stable at least up to 80°C. , Figures 3 to 5 are; it is true that the differential thermal curve of the present invention up to at least 80°C is a metal magnetic powder with various particle sizes [grinding 8 magnetic notes)] This figure shows the relationship between the chroma signal carrier-to-noise ratio, still image life, and amount of head wear of a magnetic recording medium with a conventional magnetic layer containing metal magnetic powder and abrasives of various particle sizes. This is a custom curve diagram. Patent applicant Roku Konishi Photo Industry Co., Ltd. Patent attorney Ichiyuki? i-tomi large procedure sleeve formalities (spontaneous) 1. Indication of the case 1981 Patent Application No. 91913 3, Person making the amendment Relationship to the case Patent applicant address 1-26 Nishi-Shinjuku, Shinjuku-ku, Tokyo, No. 2 L
'Den (name f+,) (127) Konishiroku Photo Studio Co., Ltd. 6, Number of inventions increasing due to amendment tx t. 7. Subject of amendment [1] The claims of the specification are revised as shown in the attached sheet. [2] The detailed description of the invention in the specification is revised as follows. (1) On page 3 of the specification, line 4, “...Abrasion resistance...
" is changed to "...abrasion resistance...". (2) Page 4 of the specification, lines 2-3: “...Abrasion resistance...
" is changed to "...abrasion resistance..." and the 9th item on the same page is [・
...oxidation stability..."
shall be. (3) "... (hereinafter simply "
"magnetic powder". )..." to "...(hereinafter, jl
i is referred to as "magnetic powder" or "r magnetic powder". "door°°". (4) Delete h [I listing on page 29 of the specification, lines 1 to 4. (5) In the 7th line of page 38 of the specification, “in the article...” is replaced with “
Under the conditions of...''. Above (Attachment) Claims A magnetic layer comprising a metal magnetic powder having a stable 7T"k thermal curve up to at least 80°C and an abrasive with a particle size of 0.5μ or less on a support. Magnetic recording medium. Procedural amendment (voluntary) October 12, 1980, 7-Mr. Kazuo Wakasugi, Commissioner of the Patent Office 1. Indication of the case 1981 Patent Application No. 91913 2. Name of the invention Magnetic recording medium 3. Relationship with the case of the person making the amendment Patent applicant name (name) (127) Konishiroku Photo Industry Co., Ltd. 6
Number of inventions increased by amendment N/A (1) Specification No. 20
The description "...binder 100..." on the 13th line of the page is changed to "...magnetic powder 100...". (2) Page 21, line 7 of the specification [...Binder 10
0・-゛'' was replaced with ``...magnetic powder 100...
”. that's all

Claims (1)

[Claims] A magnetic recording medium having, on a support, a magnetic layer containing metal magnetic powder having a stable thermal curve at least at g o 'o 1 and an abrasive having a particle size of 0.5 μm or less.