JPH02110822A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve electromagnetic conversion characteristics and traveling durability by subjecting a ferromagnetic metal powder showing an adsorption of stearic acid at 5.0X10<-6>mol/m<2> or more to surface treatment with specific triazine dithiol derivatives, dispersing the powder in a resin having specific polar groups and forming a magnetic layer with the powder and fatty acids. CONSTITUTION:The ferromagnetic metal powder showing the adsorption of stearic acid at 5.0X10<-6>mol/m<2> or more is subjected to surface treatment with triazine dithiol derivatives expressed by formula I and dispersed in such a resin having polar groups expressed by formula II to form the magnetic layer with fatty acids. In formulae I and II, X represents R1O- or the like, R1 and R2 represent alkyl groups, etc., having 1 - 18 carbons, M1, M2, M, M', R3 and R4 represent H or the like. By using a combination of the triazine dithiol derivatives and the resin having polar groups, the ferromagnetic metal powder disperses well and the obtained magnetic layer has a smooth surface. Moreover, the maximum magnetic flux density and the squareness ratio of the magnetic layer increase, which results in good electromagnetic conversion characteristics and excellent traveling durability of the medium.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium with excellent electromagnetic conversion characteristics and running durability.

[Conventional technology]

Magnetic recording media are widely used as recording tape, video tape, computer tape, or floppy disks. A magnetic recording medium basically consists of a magnetic layer in which ferromagnetic metal powder is dispersed in a binder, which is laminated on a nonmagnetic support.

Basically, magnetic recording media are required to have high levels of performance, such as electromagnetic conversion characteristics, running durability, and running performance. In particular, with the recent spread of 8mm video tape recorders, video tapes are required to have particularly excellent electromagnetic conversion characteristics, such as high video output and excellent original picture playback ability. has been done. Ferromagnetic metal powder has come to be used as a means to improve this electromagnetic conversion characteristic.

[Problem to be solved by the invention]

In order to obtain a magnetic recording medium that uses ferromagnetic metal powder and has excellent electromagnetic characteristics and running durability, various magnetic surface treatment agents that impart dispersibility and stability to the magnetic surface have been studied. <Phosphoric acid (Japanese Patent Publication No. 6O-25025), phosphoric acid ester type (Japanese Patent Application Publication No. 63-23962).

Silane coupling agent (JP 63-4417), fatty acid (JP 53-15802, JP 53-11611)
4. For example, the ferromagnetic metal powder surface-treated with the above-mentioned silane coupling agent has a high strength because the entire surface of the ferromagnetic metal powder is hydrophobized by the silane coupling agent. Although the stability of the dispersion state of the magnetic metal powder particles in the magnetic paint is usually improved, the bonding force between the resin component and the ferromagnetic powder may be conversely reduced. Therefore, the final state of dispersion of the ferromagnetic metal powder in the magnetic layer may not be sufficiently improved. Furthermore, since the silane coupling agent itself is very expensive, it is difficult to use it as a treatment agent for ferromagnetic metal powder used in ordinary magnetic recording media.

Furthermore, fatty acids, which are normally contained as lubricants in the magnetic layer of magnetic recording media, have a dispersing effect on the ferromagnetic metal powder. Therefore, it is possible to improve the dispersion state of ferromagnetic metal powder by adjusting the amount used, but in general, when fatty acids are used as a dispersant, they are more difficult to disperse than when they are blended into a magnetic layer as a lubricant. A sufficient effect cannot be obtained unless a large amount is used. On the other hand, fatty acids are known to act as plasticizers on binders when used in excess, and there is a problem that when fatty acids act as dispersants for ferromagnetic metal powders, the binders inevitably become plasticized. There is.

On the other hand, improving the dispersion state improves the surface properties of the tape and increases the coefficient of friction, resulting in a problem of poor running performance. For example, it was possible to improve the dispersion state by using a large amount of fatty acid, but this was insufficient in terms of running durability. Furthermore, surface treatment agents having a triazine ring have been proposed in recent years. (Unexamined Japanese patent publication 6l-96
519) This is because metal-based ultrafine particles are very easily oxidized in the air, and because of the large surface activity of ultrafine particles, dispersion is difficult, but surface treatment with triazinedithiol derivatives improves dispersibility. It has been discovered that it is possible to impart weather resistance. It is true that such an effect can be obtained, but simply using a triazinedithiol derivative results in a stearic acid adsorption amount of 5.0XIO-"m.
When using a ferromagnetic metal powder with a magnetic flux of at/m' or higher, running properties are improved, but it is difficult to obtain good electromagnetic conversion characteristics. This ferromagnetic powder with a high adsorption amount of stearic acid is, for example, a ferromagnetic metal powder oxidized in the gas phase, which is likely to be lower in cost and has excellent demagnetization.

In other words, when the ferromagnetic metal powder is treated with a triazine dithiol derivative, the adsorption with the ferromagnetic metal powder is extremely strong, which prevents the adsorption of fatty acids added to the magnetic coating liquid as a lubricant, and the fatty acids come out to the surface of the magnetic layer and have no lubricating function. As a result, the μ value also decreases. However, on the other hand, the adsorption between the binder and the ferromagnetic metal powder was also inhibited, resulting in poor dispersibility.

[Purpose of the invention]

An object of the present invention is to provide a magnetic recording medium particularly having good electromagnetic conversion characteristics and running durability.

More specifically, the present invention improves the electromagnetic conversion characteristics by improving the dispersion state of the ferromagnetic metal powder in the magnetic layer so that the characteristics of the ferromagnetic metal powder used are fully exhibited;
The present invention also aims to provide a magnetic recording medium that exhibits excellent running durability.

[Means to solve the problem]

The present invention has a stearic acid adsorption amount of 5. Q x IQ-'mo
A ferromagnetic metal powder of l/m' or more is surface-treated with at least one type of triazinedithiol derivative represented by (I) below, and at least one polar group among the polar groups shown in (II) below. A magnetic recording medium is characterized in that it has a magnetic layer that is dispersed in a resin having a fatty acid and contains a fatty acid.

X is R10-1R, 5-1R, NH or R7R2
N-1R1 and R2 have the same or different carbon number 1-
18 alkyl, alkenyl, aryl, aralkyl or cycloalkyl groups, and M1 and M2 represent the same or different hydrogen, alkali metal or ammonium.

(II) -3O,M, -03O,M, -CO
□14, -OP03MM', -NR8R4 where MSM' is the same or different H1 alkali metal,
or represents ammonium, and R3R4 represents the same or different H1 hydrocarbon group or alkanol group.

[Action/effect of the invention]

The magnetic recording medium of the present invention is a magnetic recording medium in which, by using a triazinedithiol derivative, this compound acts as a dispersant on the ferromagnetic metal powder, thereby improving the dispersion state of the ferromagnetic metal powder in the magnetic layer. . Specifically, by using the above triazinedithiol derivative in combination with a polar group-containing resin, the ferromagnetic metal powder is well dispersed, the surface of the magnetic layer is smooth, and the maximum magnetic flux density and squareness ratio of the magnetic layer are improved. rises. Therefore, the magnetic recording medium of the present invention exhibits good electromagnetic conversion characteristics. Furthermore, the friction coefficient is low, so it exhibits excellent running durability.

On the surface of the ferromagnetic metal powder of vapor phase metal, there are basic points (stearic acid adsorption points) and acidic points here and there, but in those that are not treated with triazine dithiol, the binder is adsorbed to the ferromagnetic metal powder. Stearic acid is adsorbed to the remaining basic points.

Therefore, the proportion of stearic acid that appears on the surface of the magnetic layer and contributes to lubrication decreased, resulting in moderate dispersibility and poor running durability.

Furthermore, when treated with a large amount of triazinedithiol, the binder also loses its adsorption sites for stearic acid.

As a result, the dispersibility is poor because adsorption of the binder does not occur. On the other hand, the amount of stearic acid released on the surface of the magnetic layer increases, and μ
The value also decreases, but on the other hand, the dispersibility is poor because no binding agent is adsorbed. In the case of the present invention, an appropriate amount of triazinedithiol is adsorbed on the surface of the ferromagnetic metal powder, and a binder having a decaying group is adsorbed to the remaining adsorption points, so that there is no place for stearic acid to adsorb. As a result, the binder and triazinedithiol are bonded to the ferromagnetic metal powder, which improves the dispersibility, and increases the amount of stearic acid exposed to the surface of the magnetic layer, which lowers the μ value and provides a good magnetic recording medium.

In this case, by using triazine dithiol as a treatment agent, the lipophilicity of the surface of the ferromagnetic metal powder becomes suitable for binding agent adsorption, and the -3H group has a strong bonding force with the ferromagnetic metal powder, making it extremely excellent. .

[Detailed description of the invention]

The magnetic recording medium of the present invention basically has a structure in which a non-magnetic support and a magnetic layer made of ferromagnetic metal powder (ferromagnetic material) dispersed in a binder are provided on the support. have

The material forming the non-magnetic support can be one that is normally used as a material for the non-magnetic support of magnetic recording media.

Examples of the material include polyethylene terephthalate, polypropylene, polycarbonate, polyethylene naphthalate, polyamide, polyamideimide, polyimide, and metal foils such as aluminum foil and stainless steel foil.

The thickness of the nonmagnetic support is usually in the range of 3 to 100 μm (preferably 5 to 80 μm).

The nonmagnetic support may be provided with a bank coat layer (backing layer) on the side where the magnetic layer is not provided.

The magnetic recording medium of the present invention includes a magnetic layer in which ferromagnetic metal powder is dispersed in a binder on a nonmagnetic support as described above.

The ferromagnetic metal powder used in the present invention is one in which a slowly oxidized film is provided on the surface of an acicular powder of an alloy whose main component is iron.

Further, alloy components other than iron include nickel, aluminum, silicon, zinc, cobal), and CrSMn.

It may also contain metals such as Cu and P. This ferromagnetic metal powder has a particle size of 0.5 microns or less, an axial length/narrow width ratio of 5 or more, and a specific surface area (BET method) of 35 m'/
g or more.

Furthermore, this ferromagnetic metal powder has a pH of 8-12.
, or stearic acid adsorption amount is 5. OXlo-6mol
/m'' or more. In particular, ferromagnetic metal powder containing iron, nickel, aluminum, and silicon, with a specific surface area of 45 m'/g or more, a pH of 9-11, and a stearic acid adsorption amount of 6 XIO It is effective when using a ferromagnetic metal powder of -6 mol/m' or more.

The amount of stearic acid adsorbed by the above-mentioned ferromagnetic metal powder was measured by the following method.

5 g of ferromagnetic metal powder was added to a 100-meter Erlenmeyer flask containing a methyl ethyl ketone solution containing 2 wt% stearic acid, the flask was tightly capped and stirred in a magnetic cooler for 25 hours, and then transferred to a centrifuge. Solid-liquid separation was performed, and the stearic acid concentration C (wt%) in the supernatant was measured using gas chromatography.

The amount of stearic acid adsorbed per unit area of the ferromagnetic metal powder was determined from the following formula.

However, SSA: ferromagnetic metal powder specific surface area (m'/g)
MW nystearic acid molecular weight (284) The magnetic recording medium of the present invention consists of a magnetic layer in which the above-mentioned ferromagnetic metal powder surface-treated with a triazine dithiol derivative is dispersed in a binder made of the above-mentioned resin component. .

Examples of the triazinedithiol derivatives represented by the general formula (1) used here include those having the following chemical structures.

Among these, a good dispersion effect is obtained when the surface of the ferromagnetic metal powder is treated with a triazine diol derivative marked with an O mark.

Examples of M, M, Examples of R1, R2 Such triazine dithiol derivatives have the property of adsorbing or bonding to metal surfaces, and in the magnetic layer, the triazinedithiol derivatives are mainly attached to the surface of the ferromagnetic metal powder. It is presumed that it exists in an adsorbed or bound state.

Therefore, the surface of the ferromagnetic metal powder becomes coated with the triazinedithiol derivative, which improves the affinity of the ferromagnetic metal powder for the resin component, or directly binds the ferromagnetic metal powder in the magnetic layer. It is presumed that the dispersion state of the particles is improved. In this case, the polar groups in the resin are believed to be bonded to reactive sites on the active surface of the ferromagnetic metal powder that is not coated with triazinedithiol.

It is believed that the triazine dithiol derivative binds to or adsorbs to the stearic acid adsorption site (basic site) of the ferromagnetic metal powder, so the amount of stearic acid adsorbed on the ferromagnetic metal powder surface-treated with triazine dithiol decreases. As a result, it is presumed that the floating rate of the added fatty acid, such as stearic acid, on the medium surface increases, resulting in excellent running durability. In other words, stearic acid is not adsorbed to the magnetic material (it appears on the surface of the magnetic layer and performs its original function as a lubricant).

The magnetic layer contains the triazine diol derivative in an amount of 0.03 to 10 parts by weight based on 100 parts by weight of the ferromagnetic metal powder. In particular, the content is 0.3 to 5.
By setting the amount within the range of 0 parts by weight, the dispersion state of the ferromagnetic metal powder becomes better, such as the glossiness of the surface of the magnetic layer becoming higher. Furthermore, by setting the content within the range of 0.5 to 3.0 parts by weight, the electromagnetic conversion characteristics are significantly improved, the friction coefficient is also reduced, and running durability is excellent.

The method for adding this triazinedithiol derivative is to dissolve or disperse it in a low boiling point organic solvent, add ferromagnetic metal powder to this solution and mix, then remove the organic solvent and pre-treat the ferromagnetic metal. A method for preparing a powder and manufacturing a magnetic recording medium using the ferromagnetic metal powder,
Further, when preparing a magnetic paint, a method may be used in which the above-mentioned triazine dithiol derivative is added, preferably in a dissolved or dispersed state, to a part of a solvent for preparing a magnetic paint to perform cross-dispersion.

The polymer used as a binder for forming the magnetic layer of the present invention is a vinyl chloride/vinyl acetate copolymer resin (e.g.
vinyl chloride/vinyl acetate copolymer, vinyl chloride/vinyl acetate/vinyl alcohol copolymer, vinyl chloride/vinyl acetate/maleic acid copolymer), vinyl chloride/vinylidene chloride copolymer, acrylic resin (e.g. chloride Vinyl/acrylonitrile copolymer, vinylidene chloride/acrylonitrile copolymer, (meth)acrylic acid ester/acrylonitrile copolymer, (meth)acrylic acid ester/vinylidene chloride copolymer, (meth)acrylic acid ester/styrene copolymer -30 as a polar group in polyurethane resins, polyester resins, polyvinyl fluoride, polyamide resins, polyvinyl butyrate, and styrene/brassene copolymers (butadiene/acrylonitrile copolymers),
3M.

O20,M, -CO□M, -OP03MM'
, -NR, R4 (wherein M, M' represent the same or different H1 alkali metals or ammonium, and R3, R4 represent the same or different H1 hydrocarbons or alkanoic groups). One type is selected from the introduced polymers. Preferred is a polymer in which a polar group is introduced into a vinyl chloride/vinyl acetate copolymer resin.

The above polar group is present in the above polymer at 10% per 1 g of polymer.
The content is preferably in the range of -6 to 10-3 equivalents.

Resins such as thermosetting resins and reactive resins can be used with the binders described above. These three types of resins can be used alone or in combination.

Thermosetting resins or reactive resins are generally resins with an average molecular weight of 200,000 or less in the coating liquid state, and resins whose molecular weight becomes almost infinite due to condensation reaction or addition reaction after coating. . However, when these resins are thermosetting resins, it is preferable that the resins are not softened or dissolved by heating during the curing process. Examples of thermosetting or reactive resins include phenol/formalin/novolak resin, phenol/formalin/resol resin, phenol/furfural resin, xylene/formalin resin, urea resin, melamine resin, drying oil-modified alkyd resin, and phenol. Resin-modified alkyd resins, maleic acid resins, modified alkyd resins, unsaturated polyester resins, combinations of epoxy resins and curing agents (e.g. polyamines, acid anhydrides, polyamide resins), terminal incyanate polyether moisture-curing resins, polyester resins Isocyanate prepolymers (e.g. reaction products of diisocyanates and low molecular weight triols - compounds with three or more isocyanate groups in the molecule, trimers and tetramers of diisocyanates) or polymers thereof, polyisocyanate prepolymers and active hydrogen (e.g., polyester polyol, polyether polyol-7L/.

Examples include resins produced by reaction with acrylic acid copolymers, maleic acid copolymers, 2-hydroxyethyl methacrylate copolymers, p-hydroxystyrene copolymers, and resins obtained by combinations thereof. can. The amount of binder used is generally 10 to 100 parts by weight, preferably 15 to 50 parts by weight, per 100 parts by weight of the ferromagnetic powder.
Parts by weight are used. .

Further, the fatty acid contained in the magnetic layer of the magnetic recording medium of the present invention is preferably a fatty acid having 14 to 22 carbon atoms,
If desired, a fatty acid amide may be further contained.

In the magnetic layer, fatty acids or fatty acid amides act as lubricants.

In this case, the content of the fatty acid or fatty acid amide is usually set within the range of 0.1 to 5 parts by weight (particularly preferably 0.3 to 4 parts by weight) based on 100 parts by weight of the ferromagnetic metal powder.

Examples of fatty acids used in the present invention include capric acid, lauric acid, undecylic acid, myristic acid, palmitic acid, stearic acid, behenic acid, montanic acid, oleic acid,
Mention may be made of elaidic acid, linoleic acid, lylunic acid, stearol, and the like. Moreover, amides of these fatty acids may be used if desired.

Furthermore, the lubricity can be further improved by using a fatty acid ester in combination as another lubricant.

When using a fatty acid ester, the content of the fatty acid ester is usually 0.1 parts by weight per 100 parts by weight of the ferromagnetic metal powder.
It is set within the range of ~5 parts by weight (particularly preferably 0.3 to 4 parts by weight).

Furthermore, when a fatty acid ester is used in combination with a fatty acid, the fatty acid and the fatty acid ester are usually used in a weight ratio of 1:9 to 9:1.

Examples of fatty acid esters contained in the magnetic layer of the magnetic recording medium of the present invention include methyl myristate, butyl myristate, octyl myristate, butyl stearate, tridecyl stearate, oleinohepalmitate, and ethyl palmitate. Mention may be made of butoxyethyl. However, it is particularly preferable that a fatty acid ester represented by the following general formula (III) is included.

However, R5: a hydrocarbon group R6 having 11 to 21 carbon atoms
: Hydrocarbon group having 1 to 8 carbon atoms R7, : Hydrogen or methyl group : Integer from 2 to 20 The fatty acid ester represented by the above general formula (II[) may be evenly contained in the magnetic layer. It is particularly effective even if it is localized on the surface of the magnetic layer. In the present invention, the general formula (III)
) Any fatty acid ester can be used. For example, R3['(CH2> I g
cOQ (C)1. cH20) 2CH3LC(CH2
) 16['OO(CH2CH20) 2C)+2CH
3H,C(CH2) l [1COO(CI(,CH2
[1) 2 (CH2) 3CH3)1. C (CH2)
I 5cOo (C)l, CH20) 2 (CH2
), C1l.

)13C(CL) l 5cOO(CH2CH20)
2 (CH2) 5CH3H3C(CHa) l gc
OO(CH2CH20) 2 (CH2) 6CH3H
3C(CH2)+sC[]0CH,CH,O) 2(
C) I2), CH.

)13c (CH2) 14C[][] (CH2CH
2C)I of z.

H,C(CI(a) l 4COO(CH2C)1.0
) 2 (CH2) 3CH.

H, C(CH2) I 4COO(C112CH20)
2 (CH2) Jiang H3HsC (CHa) + 4CO mouth (
CH2CH20)2 (C112)SCH3H,C(C
Ha) l 4COO(CH,CH20) 2 (CH
2) 6CH383C(C)12) l 4COD (
CH2C1(20>2(C)+2)t. R3 Among these fatty acid esters, those which are particularly effective are those in the general formula (I[I) in which R2 is a directly saturated hydrocarbon group, and it is more preferable that R1 is hydrogen. n is 2~
4 is particularly preferred.

The magnetic layer of the magnetic recording medium of the present invention preferably further contains inorganic particles having a Mohs hardness of 5 or more.

The inorganic particles used are not particularly limited as long as they have a Mohs hardness of 5 or more. An example of inorganic particles having a Mohs hardness of 5 or more is AlzOs (Mohs hardness 9).

T10 (6), TlO2 (6.5), 5I0
2 (same?), 5n02 (same as 6.5), Cr20
a (same as 9), and a-Fe, 0. (5.5
), and these can be used alone or in combination.

Particularly preferred are inorganic particles having a Mohs hardness of 8 or more. When inorganic particles with a Mohs hardness lower than 5 are used, the inorganic particles tend to fall off from the magnetic layer and have almost no abrasive action on the head, resulting in head clogging and poor running durability. become scarce.

The content of the inorganic particles is usually in the range of 0.1 to 20 parts by weight, preferably in the range of 1 to 10 parts by weight, based on 100 parts by weight of the ferromagnetic metal powder.

In addition to the above-mentioned inorganic particles, the magnetic layer preferably contains carbon black (particularly one having an average particle size of 10 to 300n+n (nanometers; 10-'m)).

The magnetic recording medium of the present invention contains a ferromagnetic metal powder, a binder, and the above-mentioned additives used as desired, in a commonly used organic solvent such as tetrahydrofuran, toluene, butyl acetate, ethyl acetate, methyl ethyl ketone, and cyclohexanone. A magnetic paint is prepared by dispersing the magnetic paint, and this magnetic paint is coated on a non-magnetic support so that the dry thickness of the magnetic layer is usually 0.1 to 10 μm, followed by magnetic field orientation treatment, drying, and surface smoothing treatment. and hardening treatment, etc.
It can then be manufactured using a conventional method of cutting.

Furthermore, so-called lubricating oil additives can be used alone or in combination in the present invention, such as antioxidants (alkylphenols, etc.), rust inhibitors (naphthenic acid, alkenylsuccinic acid, dilauryl phosphate, etc.), and oily agents (rapeseed oil). , lauryl alcohol, etc.), extreme pressure agents (dibenzyl sulfide, tricresyl phosphate, tributyl phosphite, etc.), detergents and dispersants, viscosity index improvers, pour point depressants, defoaming agents, etc. These lubricants are added in an amount of 0.05 to 20 parts by weight per 100 parts by weight of the binder.

Further, as the antioxidant, heterocyclic compounds and heterocompounds such as benzotriazine, penzothiazonopebenzodiazine, and EDTA can be used.

The antistatic agents used in the present invention include graphite, carbon black, carbon black graft polymer, tin oxide-antimony oxide, tin oxide, titanium oxide-tin oxide-
Conductive powders such as antimony oxide; natural surfactants such as saponins; nonionic surfactants such as alkylene oxides, glycerin, glycidol, polyhydric alcohols, esterophores, alkylphenols, and -le-EO adducts. Cationic surfactants such as higher alkylamines, cyclic amines, hydantoin derivatives, amidoamines, ester amides, quaternary ammonium salts, pyridine and other heterocycles, phosphoniums or sulfoniums; carboxylic acids, sulfonic acids, phosphoric acids , anionic surfactants containing acidic groups such as sulfate ester groups and phosphate ester groups;
Amino acids; aminosulfonic acids, sulfuric acid or phosphoric acid esters of amino alcohols, amphoteric surfactants such as alkyl betaine type, etc. are used. These surfactants may be added alone or in combination. In addition, these surfactants are added to the surface of the magnetic recording medium at a concentration of 1 mg/m+ to 550
mg/m' may be overcoated.

The amount of these surfactants used in the magnetic recording medium is 0.01 to 10 parts by weight per 100 parts by weight of the ferromagnetic fine powder. Although these are used as antistatic agents, they are sometimes used for other purposes, such as dispersion, improving magnetic properties, improving lubricity, and as coating aids.

In addition to the above-mentioned abrasives for the magnetic layer or back layer used in the present invention, commonly used materials with abrasive or polishing properties include silicon carbide, cerium oxide, corundum, artificial diamond, garnet, and emery (main ingredients: corundum and magnetite), garnet, silica, silicon nitride, boron nitride, molybdenum carbide, boron carbide, tungsten carbide, titanium carbide, quartz, tripoli, diatomaceous earth, dolomite, etc., mainly Mohs hardness 6 or higher, preferably Mohs hardness 8 The above materials are used in combinations of up to four types, and these abrasives have an average particle size of 0.005 to 5 microns.
Particularly preferred is 0.01 to 2 microns.

Examples of organic solvents used in the dispersion, kneading, and coating of the present invention include ketones such as acetone, methyl isobutyl ketone, isophorone, and tetrahydrofuran; methanol, ethanol, fluoro/-nohebutanol; inbutylalconopeisoprobil alcohol,
Alcohols such as methylcyclohexanogol; esters such as methyl acetate, isobutyl acetate, improvinope lactate, and glycol monoethyl acetate;
Ethers such as diethyl ether, glycol dimethyl ether, glycol monoethyl ether, and dioxane; Tars (aromatic hydrocarbons) such as benzene, xylene, cresol, chlorobenzene, and styrene; methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, Chlorinated hydrocarbons such as ethylene chlorohydrin and dichlorobenzene, N,N-dimethylformaldehyde, and hexane can be used.

There are no particular restrictions on the kneading method, and the order of addition of each component can be set as appropriate. For the preparation of magnetic paints and back layer paints, conventional kneading machines are used, such as two-roll mills, three-roll mills, ball mills, pebble mills, thoron mills, sand grinders, Szegva mills, etc.
ri), 7 triter, high speed impeller, dispersion machine, high speed stone minope high speed impact mill, disper, kneader
High speed mixers such as ribbon blenders, co-kneader intensive mixers, tumblers, blender dispersers, homogenizers, axle screw extruders, twin screw extruders, and ultrasonic dispersers can be used. For details on the technology related to crosstalk dispersion, please refer to T, C,
Written by PATTON (Chi, Sea, Paraton) “Pa1nt
Plow and Pigment Dispersi
on” (Paint Flow and Pigment
Disversion) 1964 John Wiley
Published by & 5ons (John Willie & Sons)
Shin Tanaka - "Industrial Materials" Vol. 25, 37 (1977)
etc., and in the cited literature of the book, and for continuous processing, these crosstalk dispersers are appropriately combined to feed and apply the liquid. Also, U.S. Patent No. 2581414 and U.S. Patent No. 285
It is also described in specifications such as No. 5156. In the present invention, a magnetic paint and a back layer paint can be prepared by carrying out crosstalk dispersion according to the method described in the above-mentioned book or the cited literature of the book.

To form the magnetic layer, the above compositions are arbitrarily combined and dissolved in an organic solvent, and a coating solution is coated on the support and dried. When used as a tape, the thickness of the support is 2.5~
The thickness is about 100 microns, preferably about 3 to 70 microns. In the case of a disk or card, the thickness is 0.
The diameter is about 0.3 to 10 mm, and in the case of a drum, it can also be used in a cylindrical shape. Materials include polyesters such as polyethylene terephthalate and polyethylene naphthalate,
Polyolefins such as polypropylene and polyethylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, plastics such as polycarbonate, polyamide, and polysulfone, as well as metals such as aluminum and copper, Ceramics such as glass can also be used. Prior to coating, these supports may be subjected to corona discharge treatment, plasma treatment, undercoating treatment, heat treatment, dust removal treatment, metal vapor deposition treatment, and alkali treatment.

Methods for coating the magnetic layer and back layer on the support include air doctor coating, blade coating, air knife coating, squeeze coating, impregnation coating, reverse roll coating, transfer roll coating, gravure coating, kiss coating, cast coating, and spray coating. Coatings, barcodes, spin codes, etc. can be used, and other methods are also possible, and detailed explanations of these can be found in "Coating Industry" published by Asakura Shoten, pages 253 to 277 (1977).
, 3. 20. Publication).

In particular, when the magnetic layer has a multilayer structure, a so-called wet-on-wet coating method is preferred in which the t' layer coating liquid and the upper layer coating liquid are applied in a superimposed state in a wet state.

As a wet-on-wet method, JP-A-61-139
The coating method described in Japanese Patent No. 929 can be used.

Further, details of the method of dispersing the above-mentioned ferromagnetic powder and binder and the method of coating it on a support are described in various publications such as JP-A-54-4601i and JP-A-54-21805.

By such a method, the magnetic layer coated on the support is subjected to a treatment 4 in which the magnetic powder in the layer is immediately dried and oriented in a desired direction, if necessary, and then the formed magnetic layer is dried. The transport speed of the support at this time is usually 10 m.
/min~1000m/min, drying temperature is 20℃
Controlled at ~130°C. Further, if necessary, the magnetic recording medium of the present invention is manufactured by subjecting it to surface smoothing processing and cutting it into a desired shape. These manufacturing methods include filler surface treatment, kneading/dispersion, coating, heat treatment, calendaring, and
It is preferable to perform the steps of B treatment, surface polishing treatment, and cutting in succession. Moreover, the process can be divided into several parts as necessary.

In these processes, temperature and humidity are controlled, and the temperature is 10°C to 130°C, and the humidity is expressed as the amount of moisture in the air.
5 mg/m' to 20 mg/m"1, these are shown, for example, in Japanese Patent Publication No. 40-23625, Japanese Patent Publication No. 39-28368, U.S. Patent No. 3473960, etc. .

Furthermore, the method disclosed in Japanese Patent Publication No. 41-13181 is considered to be one of the fundamental and most important techniques in this field.

The present invention will be explained in more detail below using Examples. It will be readily understood by those skilled in the art that the components, proportions, order of operations, etc. herein may be modified without departing from the spirit of the invention.

Therefore, the invention should not be limited to the examples below.

(Example) Examples and comparative examples of the present invention will be shown. A magnetic tape was prepared using the composition shown below as a basic composition. However, the properties of the ferromagnetic metal powder, the types of triazinethiol derivative, binder resin, fatty acid, and fatty acid ester and their blending ratios are as shown in Table 1.

Magnetic coating composition Coercive force + 150006 8 parts by weight of polyurethane resin Using a portion of the cyclohexanone in the above composition, a 5% by weight cyclohexanone solution of a triacycinediothyl derivative was prepared.

The obtained cyclohexanone solution and the above ferromagnetic metal powder were kneaded and dispersed for one hour using a ball mill, and then the remaining components of the composition were added thereto, and the mixture was further kneaded and dispersed for 48 hours. After kneading and dispersing, 8 parts by weight of an incyanate compound (manufactured by Bayer AG, Desmodur L) was added thereto, mixed for another hour, and then filtered using a filter with an average pore size of 1 μm to remove the magnetic paint. Prepared. The obtained magnetic paint was applied onto the surface of a polyethylene terephthalate support having a thickness of 10 μm using a reverse roll so that the thickness of the magnetic layer after drying was 4.0 μm.

The non-magnetic support coated with the magnetic paint is subjected to magnetic field orientation treatment using a 3000 Gauss magnet while the magnetic paint is not dried, and after drying, supercalender treatment is performed.

The tape was slit to a width of 8 mm to produce an 8 m [II] videotape.

Stearic Acid Adsorption Amount The stearic acid adsorption amount of the ferromagnetic metal powder was measured by the following method.

5 g of ferromagnetic metal powder was added to a 100 mf Erlenmeyer flask containing a methyl ethyl ketone solution containing 2 wt % stearic acid, the flask was tightly stoppered, and the mixture was stirred in a magnetic cooler for 25 hours. Next, solid-liquid separation was performed using a centrifuge, and the stearic acid concentration C (wt%) in the supernatant was determined.
) was measured using gas chromatography.

The amount of stearic acid adsorbed per unit area of the ferromagnetic metal powder was determined from the following formula.

However, SSA: ferromagnetic metal powder specific surface area (m''/g
) Mw Nistearic acid molecular weight (284) IBC formula Friction coefficient The obtained videotape and a stainless steel pole were brought into contact (wrapping angle 180°) with a tension of 50g (T1), and under these conditions, the videotape was The tension (T2) required to run at a speed of .3 cm/s was measured. Based on this measured value, the friction coefficient μ of the videotape was determined using the following calculation formula.

p = 1 / yr ・1n (T2/Tl) The friction coefficient test was carried out under the conditions of 20°C and 70% RH.Tea, VT
The tests were conducted under two conditions: R not running, b, and after running 100 passes on the VTR.

The results are shown in Table 2.

C/N ratio Commercially available GMM video tape recorder (Fujix-3
) was used to record a 5 MHz signal, the noise generated within the range of 5±I MHz when this signal was reproduced was measured, and the ratio of the reproduced signal to this noise was measured. The measurement was performed using an NV-870HD output level measuring device (manufactured by Matsushita Electric Industrial Co., Ltd.). Note that the values shown are values when the C/N ratio of the magnetic recording medium obtained in Comparative Example 1 is expressed as OdB.

The evaluation results are shown in Table 2.

Claims (1)

[Claims] 1) Stearic acid adsorption amount 5.0×10^-^6 mol/
m^2 or more ferromagnetic metal powder is surface-treated with at least one triazine dithiol derivative represented by the following general formula (I), and a resin having at least one polar group among the polar groups shown in the following (II) is prepared. A magnetic recording medium comprising a magnetic layer containing a fatty acid dispersed therein. (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ X is R_1O-, R_1S-, R_1NH or R
_1R_2N-, R_1 and R_2 represent the same or different alkyl, alkenyl, aryl, aralkyl or cycloalkyl group having 1-18 carbon atoms, M_1,
M_2 represents the same or different hydrogen, alkali metal, or ammonium. (II) -SO_3M, -OSO_3M, -CO_2M,
-OPO_3MM', -NR_3R_4 where M and M' are the same or different H, alkali metal,
or represents ammonium, and R_3R_4 represents the same or different H, a hydrocarbon group, or an alkanol group.