JPH03127326A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a medium having low friction, no reduction in output, or no problem about head adsorption or jitter by using a resin having specified polar groups as a binder in a magnetic layer, and incorporating fluorine silane compd., higher fatty acid and higher fatty acid ester as a lubricant. CONSTITUTION:The magnetic layer contains ferromagnetic powder dispersed in a binder. At least one of resins incorporated into the binder by >5wt.% is selected from epoxy resin, -COOM, -SO3M, -OS3M, -PO3M, -OPO3M2, -NR2, and -NR3X (wherein M is hydrogen, alkali metal, or ammonium, R is alkyl group, X is cation remaining group) by the amt. of 1X10<-6> - 1X10<-4> equiv. to 1g of the polymer. The magnetic layer also contains a fluorine silane compd., expressed by formula I, higher fatty acid, and higher fatty acid ester. In the formula I, R<1> is a hydrogen group of 1 - 6 carbon number, R<2> is a hydrocarbon group of 7 - 21 carbon number, (m) is 1 - 12, (l) is 1 - 20, and (n) is 0 - 2. Thereby, the obtd. medium has excellent traveling property and durability even after stored at high temp. and high humidity, and causes no problem about head adsorption or jitter.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a magnetic recording medium having a magnetic layer formed by dispersing ferromagnetic fine powder in a binder on a non-magnetic support.
The present invention relates to a magnetic recording medium that has excellent durability and good electromagnetic conversion characteristics.

(Prior art) In magnetic recording media, the demand for high-density recording is increasing,
Therefore, methods for reducing the particle size of ferromagnetic fine powder,
Improved dispersibility of ferromagnetic fine powder, improved surface properties of magnetic layer,
It is necessary to improve the degree of filling of ferromagnetic fine powder.

To improve the dispersibility of ferromagnetic fine powder
41565, JP-A-57-44227, JP-A-59-3
0235, JP-A-60-238306, JP-A-60-2
38309, JP-A-60-238371 and other publications include -3OJ, -OSOjM.

It has been disclosed to use a binder containing a polar group such as -pQsMz, 0POJt, -coov, or a binder having both these polar groups and an epoxy ring.

These binders have a high adsorption power to the ferromagnetic fine powder and provide better dispersibility than conventional binders. The magnetic surfaces of magnetic recording media obtained by dispersing ferromagnetic fine powder using these resins are smooth, making them suitable for video tape recorders, audio tape recorders, etc.
(hereinafter abbreviated as "deck") makes it difficult to run the magnetic tape and its durability, resulting in a stick-slip phenomenon or a stoppage in running. In other words, the phenomenon is that the finer the ferromagnetic powder and/or the smoother the surface of the magnetic layer, the worse the running properties and durability of the magnetic recording medium are for high-density recording and high S/N recording. Therefore, the emergence of a magnetic recording medium capable of high-density recording with good running performance and durability has been awaited.

In order to impart runnability and durability, the use of fatty acids, fatty acid esters, hydrocarbons, silicone compounds, fatty acid amides, mineral oil, etc., added to magnetic coating liquids is disclosed in Japanese Patent Application Laid-Open No. 1973-1999.
3505, Special Publication No. 47-15624, Special Publication No. 43-23
889, Japanese Patent Publication No. 51-39081, etc., but when the crystallite size of ferromagnetic fine powder is reduced to 500 Å or less for high-density recording, the addition of the lubricant disclosed above no longer improves runnability and durability. However, these technologies cannot produce magnetic recording media with high electromagnetic characteristics that improve the dispersibility of ferromagnetic fine powder with a crystallite size of 500 angstroms or less, and it is difficult to obtain magnetic recording media with high electromagnetic characteristics for high-density recording. Making the magnetic fine powder finer did not work effectively.

Furthermore, the durability and runnability of the squares described in the above-mentioned publications are unsatisfactory, and this worsens even further when the surface properties of the magnetic layer are smoothed in order to improve the electromagnetic conversion characteristics.

As a result of repeated experiments to add an appropriate lubricant to magnetic recording materials, the present inventors found that surfactants added to magnetic recording media lower surface energy and have appropriate diving and oil repellency. , and that it must be reasonably compatible with the material of the magnetic recording medium.

We have discovered that there is a fluorine-based surfactant with a specific chemical structure as a material that meets these conditions.

As a technology prior to the present invention, an application containing a fluorine-based surfactant having a CFs group at the terminal (Japanese Patent Application Laid-Open No. 53-57004
), but this application uses a fluorine surfactant with a low boiling point, and since it is actively devised to remain in the magnetic layer, it will be distilled off during the drying process, etc., and the effect will not be fully exerted. It did not reach.

In order to solve these problems, the patent application No. 61-292
proposed perfluorosulfonamide compounds in 222. This material had poor solubility in organic solvents and was difficult to use. This method certainly lowered the friction coefficient and improved the reproduction RF output sensitivity.

Furthermore, JP-A-57-92424 and JP-A-59-22228 propose that fluorine-containing organosilicon compounds reduce μ and exhibit good effects in repeated running tests.

However, these effects were not maintained after storage at high temperature and high humidity, and there were problems such as an increase in μ value, head adhesion of the magnetic layer, and occurrence of jitter.

Therefore, the present inventors have conducted intensive studies on binders and other lubricants, etc., in order to effectively exhibit the water solubility and oil repellency of fluorine-containing compounds, and to maintain the effects to the maximum extent possible. The present inventors have discovered that the above-mentioned drawbacks can be significantly overcome by combining a binder and a lubricant, leading to the present invention.

(Objective of the Invention) An object of the present invention is to provide a magnetic recording medium that has excellent runnability and durability even after storage at high temperatures and high humidity, and does not cause problems such as head adhesion and jitter in the magnetic layer.

(Structure of the Invention) That is, the above object of the present invention is to provide a magnetic recording medium in which a magnetic layer in which ferromagnetic powder is dispersed in a binder is provided on a non-magnetic support, in which the binder accounts for 5% by weight or more. At least one of the resins has an epoxy group, C00M, 5
05M, 033M, PO3M2- OPO,M
,, -NR+ , -NR3Xe (where M represents hydrogen, alkali metal, ammonium, R is an alkyl group,
represents a cationic residue) in an amount of I X L O-' to l Xl0-' per gram of the polymer, and the magnetic layer contains a fluorosilane compound represented by the following general formula, a higher fatty acid and This can be achieved by a magnetic recording medium characterized by containing a higher fatty acid ester.

I0 CF3 (CFri 1N (CH2) 75t (OCOR)
)s -6R1 = monovalent hydrocarbon group R2 having 1 to 6 carbon atoms, saturated or unsaturated monovalent hydrocarbon group having 7 to 21 carbon atoms m: 1 to 12 1: 1 to 20 n: O to 2 Preferably, the magnetic layer contains a fluorosilane compound, a fatty acid, and a fatty acid ester in a weight ratio of 0.1 to 2.0:0.2.
~1.5:0.2~1. This can be achieved by a magnetic recording medium characterized by comprising:

In other words, in the present invention, the polar group of the binder and the ester moiety of the fluorosilane compound have a strong interaction due to their polarity, and the fluorine-containing moiety, which has water- and oil-repellent properties, is uniformly aligned outward. , the fatty acid imparts appropriate plasticization to the binder, or the fatty acid ester acts as a carrier to supply the fluorosilane compound to the surface of the magnetic layer, acting synergistically to lower the coefficient of friction (μ value), This is a magnetic recording medium that does not cause problems such as head adhesion and jitter.

Examples of the binder used in the present invention include vinyl chloride resins, vinyl chloride/vinyl acetate copolymers, vinyl chloride and vinyl alcohol, copolymers of maleic acid and/or acrylic acid, and vinyl chloride/vinylidene chloride copolymers. Coalescence, vinyl chloride/acrylonitrile copolymer, ethylene/
Examples include vinyl acetate copolymers, cellulose derivatives such as nitrocellulose resins, acrylic resins, polyvinyl acetal resins, polyvinyl butyral resins, epoxy resins, amide resins, phenoxy resins, and polyurethane resins.

Among these, polyurethane resins and vinyl chloride resins are preferred.

The binder used in the present invention is 5% by weight of the total binder.
At least one of the above resins is an epoxy group, -COOM, -3o, M.

-osos M, -PO,M, , -0PO,M,, Φ -NR,, -NRs Xe (,: where M represents hydrogen, an alkali metal, or ammonium, R is an alkyl group, and The polar groups selected from the polymer t
The resin contains ix t o-' to t x io-' equivalents per gram.

In the case of polyester-based polyurethane, the main chain skeleton may be polyester, polyether, polyester ether, polycaprolactone, polycarbonate, or the like. The most commonly used is polyester. Specific examples of dibasic acids used in these are oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanoic acid, maleic acid, fumaric acid, itaconic acid, trimethyladipic acid, and hexahydrophthalic acid. Acids such as tetrahydrophthalic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, etc. can be used. Examples of dihydric alcohols include ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octane methylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 2,2-dimethylpropane-1,3 -diol, 2,2-diethylpropane-1,3-diol, cyclohexane-1,3-diol, cyclohexane-1,
4-diol, cyclohexane-1,4-dimetatool, cyclohexane-1,3-dimetatool, 2,2-bis(4-hydroxyethoxy-cyclohexyl)propane, 2゜2-bis(4-hydroxyethoxy-phenyl)propane, 2,2-bis(4-hydroxyethoxy,
phenyl)propane, etc. can be used. It is also possible to use a lactone-based polyester skeleton made of γ-butyrolactone, δ-valerolactone, ε-caprolactone, or the like. Also, as polycarbonate type, l,
6-hexanediol, 1.8-octanediol,
1. Carbonic esters such as to-decanediol can be used.

Incyanates that form urethane bonds include 2,
．． 4-tolylene diisocyanate 2,6-tolylene diisocyanate, l,3-xylylene diisocyanate,
■, 4-xylylene diisocyanate, l, 5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 3,3-dimethylphenylene diisocyanate, 4,4-diphenylmethane diisocyanate, 3,3-dimethyl-4,4- Polyvalent isocyanates such as diphenylmethane diisonanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and tolylene diisocyanate triadduct of trimethylolpropane can be used. Further, a part of the dibasic acid and dihydric alcohol may be replaced with trivalent or higher hydric acids and alcohols.

As a method for introducing a polar group, a method using a polar group-containing monomer as a constituent component of the polymer is generally used. Examples of polar group-containing monomers include 5-sodium sulfoisophthalic acid and 2-potassium sulfoisophthalic acid.

The molecular weight is t,ooo to 100,000, preferably 2,000 to 50,000, particularly preferably 3
,000 to 30,000.

If the amount of polar groups is out of this range, the dispersibility of the ferromagnetic fine powder will be poor, leading to a decline in electromagnetic conversion characteristics and deterioration in durability.

If the molecular weight is less than 1000, the magnetic layer of the obtained magnetic recording medium will be too strong, causing problems such as cracking when bent or curling of the magnetic recording medium due to heating during processing or storage. It's easy to do. On the other hand, the molecular weight is 100
If it exceeds .000, the solubility in the solvent tends to be poor, which not only makes handling inconvenient, but also deteriorates the dispersibility of the magnetic material and requires a large amount of energy for curing, which is not preferable.

Some polyvinyl chloride resins have a molecular weight of 3
,000~so,ooo preferably 8°000~30,
It is 000. Outside this range, curing properties may be poor or durability may be poor.

These vinyl chloride resins are based on polyvinyl chloride polymers such as vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, and vinyl chloride-vinyl acetate-vinyl alcohol copolymer. Polymer, vinyl chloride-vinyl acetate-maleic acid-vinyl alcohol copolymer, vinyl chloride-vinyl propionate-vinyl maleate copolymer, vinyl chloride-vinyl propionate-vinyl alcohol copolymer, vinylidene chloride-vinyl acetate- Maleic acid copolymer, vinylidene chloride-vinyl propionate-vinyl alcohol copolymer, vinyl chloride-
Vinyl chloride resins such as vinyl acetate-acrylic acid copolymer, vinyl chloride-vinyl acetate-acrylic acid-vinyl alcohol copolymer, and copolymers thereof may be used after being saponified.

Further, as a method for introducing a polar group, for example, the following method can be mentioned. A part of the hydroxyl group or carboxyl group of the above-mentioned base copolymer or a part of the hydroxyl group generated by saponification is reacted with one NGO group of the polyfunctional isocyanate, and the remaining NC○ group is reacted with one NGO group of the polyfunctional isocyanate. Co, H group, SO, M group, POP, M
It can be obtained by reacting a hydroxyl compound containing two or more groups.

The method of introducing these groups is not limited to the above-mentioned method. Synthesis examples of these resins are given in JP-A-61-8920.
No. 7, No. 61-106605, No. 57-40744, No. 59-8126, etc. The resins that can be used in the present invention are not limited to these synthetic examples. For both vinyl chloride resin and polyurethane resin, Cot 8% Sow N is particularly preferable as a polar group.
a is a group, and the content is 1 per 1 g of polymer.
It is preferable that the ferromagnetic powder contains about 0-7 to 101 equivalents, and more preferably 10-' to 5×1O-' equivalents. Outside this range, the dispersibility of the ferromagnetic powder will be poor, and the electromagnetic conversion characteristics will also be significantly deteriorated. descend.

Specific examples of the fluorosilane compound used in the present invention include the following.

kl CL CFaCFz(C)lr)zSi(OCOCllHas
)2N Sumi 2 (CL)t CP3CF! (CHril 0SIOCOCI 7H3S
Na3 CH3 CFs(CFx)s(CHt)tsi(OCOCtHl
s) tN 4 CH.

CFs(CF2)i(CL)zsi(OCOC+ +H
tt)*Nα5 CH.

CFs(CF2)z(CH2)zsi(OCOClst
(s+LN 6 (CH3) ICF
s(CFt)x(CL)tsiOcOc+7Hs+Na
7 CH.

CFx(CFz)s(CHt)tsi(OCOC2+H
45) 2N[L8 C8゜CF3
(CF,)s(CHt)tsi(OCOCs)I+ 9
)1No, 9 (CHz)tCFs
(CFz)s(Cut)xsi-OCOCll N to L OC1(.

CPs(CFt)s(CHz)gsi(OCOC,,H
2□)! N(LIL CHs CFs(CFt)t(CHa)zsi(OCOC+ s
H*z)*漱12 CH.

CFs(CFs)y(CHt)+aSi(OCOC+3
Htt)zN(Li2CH.

CFz(CFt)v(CHt)tsi(OCQC+ +
Hts)tN(L 14 (CHs) CFs(CFt)y(Ctlz)4SiOCOC+Js
NOL15 CHa CPs(Ch)・(CHl)zsi(OCOCtdls
i) tN(116 CI.

CFs (CFt). (CHz)zSi(OCOC*!(
+*)tN(Li2CH.

CPs(Crt)s(CHa)nsi(OCOC+t
H23) 2NtL18 (CHa) to C
Fs(CFs)s(CHt)ssiOcOc+. 0SS
N(Li2 CHa Ch(CFt)++(CHx)xsi(OCOC,H+
+)tNN2O2F2(CFt) (CHri! (CHt)sSiQCOCItH3s These compounds may be used alone or in combination.

As a method for synthesizing these compounds, a chloroalkyl group-containing chlorosilane represented by Rζ F(CF2)-(C)It) 45iCf 3-R and R''C
It is obtained by dehydrochlorinating a fatty acid represented by 0OH in the presence of a hydrochloric acid scavenger. Preferred hydrochloric acid scavengers include triethylamine, pyridine, picoline,
Examples include N,N dimethylaniline.

The preferable range of these compounds is that R' is a hydrocarbon group having 1 to 6 carbon atoms, examples of which include methyl, ethyl, propyl, butyl, pentyl, and hexyl groups, which are easily synthesized. Methyl group is most preferred because of the following.

R2 is a saturated or unsaturated monovalent hydrocarbon group having 7 to 21 carbon atoms, and among these, those having a linear structure are preferred. If the number of carbon atoms is less than 7, the lubricity will be insufficient,
On the other hand, if it exceeds 21, the melting point of the compound becomes too high, which tends to cause blooming, and the solubility in the binder becomes poor. Such monovalent hydrocarbon groups include heptyl group, octyl group, nonyl group, decyl group,
Examples include dodecyl group, tridecyl group, pentadecyl group, heptadecyl group, hexadecyl group, octadecyl group, behenyl group, olein group, linole group, and linol group.

m needs to be in the range of 1-12; if it is less than 1, the lubricity and bleed-out properties on the tape surface will be poor; on the other hand, if it exceeds 12, the solubility in solvents and binders will be extremely poor. decreases to

The fluorosilane compound of the present invention is used in an amount of 0.1 to 2.0 parts by weight, preferably 0.1 to 1.0 parts by weight, per 100 parts by weight of ferromagnetic fine powder.
If the amount is less than this, the lubricating effect cannot be achieved, and if it is more than this, the magnetic recording medium tends to stick, causing stick-slip (Stick 5 lit) phenomenon, and the pot life of the magnetic coating liquid is reduced. This is not desirable as it may become defective.

The fluorosilane compound of the present invention can be used by being added to a magnetic coating liquid, but after forming a magnetic recording layer, it may be dissolved in an organic solvent and applied or sprayed.

The higher fatty acids used in the present invention preferably have 8 to 29 carbon atoms, and specifically include decanoic acid, undecanoic acid,
Dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid (stearic acid) arachidic acid, behenic acid, montanic acid, oleic acid, palmitoleic acid, erucic acid, elaidic acid, linoleic acid, liluic acid Hexadecanoic acid, octadecanoic acid, arachidic acid, and behenic acid are particularly effective.

Specific examples of higher fatty acid esters used in the present invention include butyl stearate, butyl isostearate, 2-ethylhexyl myristate, 2-hexyldecyl stearate, isotridecyl stearate, butoxyethyl stearate, and diethylene glycol monobutyl ether stearate. In addition to monoesters, polyvalent esters such as dicetyl adipate and glycerin tristearate can be mentioned.

The amounts of the fluorosilane compound, fatty acid, and fatty acid ester used are 0.0 by weight. l~2.0:0.2~1.5+0.2
~1. It is preferable to use 5.

In addition, when applying a top coat to the surface of the magnetic layer, 5~300cm
/d, it is preferable to use a lubricant having the above ratio, especially 1
It is preferable to use 0 to 50 .mu./po.

In the present invention, methods for making higher fatty acids, higher fatty acid esters, fluorosilane compounds, etc. exist include a method of incorporating them into the magnetic layer, and a method of topcoating the surface (dissolving the material in an organic solvent, coating or spraying it on the substrate, and then drying it. Methods include melting the material and applying it to the substrate, methods such as immersing the substrate in a solution of the material dissolved in an organic solvent and adsorbing the material to the substrate surface, and methods such as the Langmuir-Prodgett method. be.

In the present invention, other lubricants may be mixed.

Lubricants that can be used together include metal soap, fatty acid amide,
Paraffins, silicone oils, animal and vegetable oils, mineral oils, higher aliphatic amines; inorganic fine powders such as graphite, silica, molybdenum disulfide, tungsten disulfide; polyethylene, polypropylene, polyvinyl chloride, ethylene-vinyl chloride copolymer, polyester Fine resin powders such as tetrafluoroethylene; α-olefin polymers; unsaturated aliphatic hydrocarbons, fluorocarbons, etc. that are liquid at room temperature.

The preferred usage amount of these mixed lubricants varies depending on the mode of use, but is generally 1/10 to 10 times the usage amount of the fluorine-containing silane compound of the present invention.

As the ferromagnetic fine powder used in the present invention, ferromagnetic alloy powder, ferromagnetic iron oxide fine powder, Co-doped ferromagnetic iron oxide fine powder, ferromagnetic chromium dioxide fine powder, barium ferrite, etc. can be used. The acicular ratio of the ferromagnetic alloy powder, Co-doped ferromagnetic iron oxide fine powder, ferromagnetic iron oxide, and chromium dioxide is about 2/1 to 20/l, preferably 5/1 or more, and the average length is Q, 2. A range of about /2.0 μm is effective.

The present invention is particularly effective when the crystallite size is 500 angstroms or less, and even more effective when the crystallite size is 400 angstroms or less.
less than angstrom. 250 is the most effective
angstrom or less (crystallite size is determined by X-ray diffraction). However, according to the gist of the present invention, effects such as electromagnetic conversion characteristics, runnability, and durability can be achieved by using the technology of the present invention even when the crystallite size is above this size, and it is effective when the crystallite size is below the above-mentioned crystallite size. . The ferromagnetic alloy powder has a metal content of 75% by weight or more, and 80% by weight or more of the metal content is a ferromagnetic metal (i.e., Fe, Co, NiXFe-Ni).
, Co-Ni, Fe:Co-N1).

The inorganic particles used are not particularly limited as long as they have a Mohs hardness of 5 or more. Examples of inorganic particles having a Mohs hardness of 5 or more include Aj'10s (Mohs hardness 9), Ti0 (6), T102 (6.5), 5102 (7), and 5n.
Oz (6.5), Cr20z (9), and aFe
+oa (same as 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.

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 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 300 nm (nanometers; 10-''m)).

As the material of the non-magnetic support, polyesters such as polyethylene terephthalate and polyethylene 2,6-naphthalate; polyolefins such as polyethylene and polypropylene; cellulose derivatives such as cellulose triacetate; resins such as polycarbonate, polyimide, and polyamideimide can be used. If necessary, it may be metallized with a metal such as aluminum.

The thickness of the support is 3 to 100μ, preferably 3 to 20μ for magnetic tape, and 20 to 100μ for magnetic disk.
μ is the commonly used range.

Next, an example of a method for manufacturing the magnetic recording medium of the present invention will be described.

First, a ferromagnetic powder, a binder, a lubricant disclosed in the present invention,
Then, if necessary, other fillers, additives, etc. are kneaded with a solvent to prepare a magnetic paint. As the solvent used in the crosstalk, a solvent commonly used for preparing magnetic paints can be used.

There is no particular restriction on the method of cross-talk, and the order of addition of each component can be selected as appropriate.

When preparing a magnetic paint, known additives such as dispersants, antistatic agents, lubricants, etc. can also be used.

Examples of dispersants include aliphatic amines, higher alcohols,
Known dispersants such as polyalkylene oxide alkyl phosphates, alkyl phosphates, alkyl borates, sarcosinates, alkyl ether esters, trialkyl polyolefins, oxyquaternary ammonium salts and lecithin can be mentioned.

When using a dispersant, the ferromagnetic powder 1 usually used is
0.00 parts by weight. It is used in an amount of 1 to 10 parts by weight.

Examples of antistatic agents include conductive fine powders such as carbon black and carbon black graft polymers; natural surfactants such as saponins; nonionic surfactants such as alkylene oxides, glycerins, and glycidols; higher alkyl amines. cationic surfactants such as quaternary ammonium salts, salts of pyridine and other heterocyclic compounds, phosphoniums or sulfoniums;
Anionic surfactants containing acidic groups such as carboxylic acid, phosphoric acid, sulfuric acid ester groups, and phosphoric ester groups; Ampholytic surfactants such as amino acids, aminosulfonic acids, and sulfuric or phosphoric esters of amino alcohols. Can be done.

When using the above conductive fine powder as an antistatic agent, for example, 0.1-10 parts by weight per 100 parts by weight of ferromagnetic powder.
It is used in a range of parts by weight, and when a surfactant is used, it is also used in a range of 0.12 to 10 parts by weight.

Note that the additives such as dispersants, antistatic agents, and lubricants mentioned above are not described with the strict limitation that they have only the above-mentioned effects; for example, if the dispersant is a lubricant, Alternatively, it may act as an antistatic agent. Therefore, it goes without saying that the effects of the compounds exemplified by the above classifications are not limited to those listed in the above classifications, and when using a substance that has multiple effects, the amount added should be It is preferable to decide in consideration of the action and effect.

The magnetic paint thus prepared is applied onto the non-magnetic support described above. Coating can be performed directly on the non-magnetic support, but it can also be applied onto the non-magnetic support with an intermediate layer such as an adhesive layer interposed therebetween. The intermediate layer herein refers to a layer of adhesive alone or a composite film layer formed by dispersing non-magnetic fine particles such as carbon in a binder.

The effects of the present invention are also noticeable when the magnetic layer consists of a plurality of layers. A similar effect appears when multiple magnetic layers are applied simultaneously.

The carbon-containing intermediate layer can be arbitrarily selected as a binder from among various binders used in magnetic layers. The particle size of carbon is 10 to 50 nm (nanometer; 1
0-'m) is preferred, and the binder:carbon weight ratio is preferably 100:10 to 100:150. The thickness of the intermediate layer is 0.1 if it is just an adhesive layer.
~2μm, 0.5~4μm for composite layer containing non-magnetic powder
m is preferred.

In addition, a lubricant that is the same as or different from the lubricant used in the magnetic layer may be added to the intermediate layer.

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 Japanese Patent Laid-Open Publications No. 54-46011 and No. 54-21805.

The thickness of the magnetic layer coated in this way is generally about 0.05 mm after drying. In the range of 5-10 μm, usually 0.
It is coated to a thickness of 7 to 6.0 μm.

When a magnetic recording medium is used in the form of a tape, the magnetic layer coated on the non-magnetic support is usually subjected to a treatment for orienting the ferromagnetic powder in the magnetic layer, that is, a magnetic field orientation treatment, and then dried. On the other hand, in the case of a disk-shaped medium, non-orientation treatment is performed using a magnetic field in order to eliminate anisotropy in magnetic properties. Thereafter, surface smoothing treatment is performed as necessary.

(Effects of the Invention) The present invention provides an epoxy group, -COO, as a binder in the magnetic layer.
By using resins with polar groups such as M, -sow M, POiMt, etc., and containing fluorosilane compounds, higher fatty acids, and higher fatty acid esters as lubricants, the friction coefficient is low even under a wide range of temperature and humidity conditions, and output decreases. Therefore, a magnetic recording medium that does not cause problems such as bed adhesion and jitter can be obtained.

The reason for this is not certain, but the polar group contained in the binder interacts with the ester moiety of the fluorosilane compound, and the fluorine-containing moiety, which has water and oil repellency, is absorbed by the anchor effect and is directed outward. Uniform alignment provides excellent durability, moisture resistance, and dust adhesion prevention effect that is unaffected by environmental factors such as temperature and humidity.

This is because fluorine has an extremely excellent surface modification effect that lowers the surface energy, so even if part of the magnetic layer is scraped off, it will not stick to the magnetic head.

Therefore, a decrease in output can be effectively prevented.

In addition, higher fatty acids and higher fatty acid esters have the effect of lowering the coefficient of friction, but in addition to this, higher fatty acids also have the effect of appropriately plasticizing the binder, increasing molecular movement and causing the lubricant to reach the surface of the magnetic layer. It has the effect of making it easier to seep out. In addition, higher fatty acid esters are compatible with fluorosilane compounds,
Acts as a carrier, making it easier to transport lubricant to the surface of the magnetic layer rather than inside the layer. This is thought to be because the higher fatty acid ester is liquid and easily dissolves the fluorosilane compound. In addition, the lubricant adheres not only to the magnetic layer but also to the magnetic head and metal parts, and because it is water and oil repellent, the combination of higher fatty acids and higher fatty acid esters maintains its effectiveness even after repeated running. It is thought that problems such as jitter will not occur.

〔Example〕

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

In addition, the expression "1 part" in the examples indicates "part by weight."

[Example 1] After cross-dispersing the following composition for 48 hours using a ball mill, 5 parts of polyisocyanate was added thereto, and after cross-dispersing for another hour, it was cross-dispersed using a filter having an average pore size of 1 μm. It was filtered and a magnetic paint was prepared. The obtained magnetic paint was coated on the surface of a polyethylene terephthalate support with a thickness of 10 μm using a one-bar roll so that the thickness after drying was 4.0 μm.

Magnetic paint composition Ferromagnetic alloy powder (composition: Fe94%, Zn4%, N+2
%,; anti-magnetic crab 15000e; specific surface area 54rrr/g
) Abrasive (α-alumina, average particle size 0.3 μm) 5 parts Lubricant (listed in Table 1) Oleic acid 1 part Carbon black (average particle size 40 nm) 2 parts Methyl ethyl ketone
A non-magnetic support coated with 300 parts of magnetic paint was oriented in a magnetic field with a 3000 gauss magnet while the magnetic paint was not dried, and after drying, supercalendering was performed and slit into a width of 8m+n. 8m
m videotape was produced. (Sample kl~18) [
Example 2 The following composition was cross-dispersed for 48 hours using a ball mill, 5 parts of polyisocyanate was added thereto, cross-dispersed for another hour, and then filtered using a filter having an average pore size of 1 μm. A magnetic paint was prepared. The thickness of the obtained magnetic paint after drying is 4. The coating was applied to the surface of a polyethylene terephthalate support with a thickness of 10 μm using a reverse roll so that the coating thickness was 0 μm.

Magnetic paint composition Ferromagnetic alloy powder (composition: 94% Fe, 4% Zn.

Ni2%: coercive force +15000e; specific surface area 54rrr
/g) 100 parts vinyl chloride/vinyl acetate/maleic anhydride copolymer (Nippon Zeon (
Made by Kiki 400X110A, degree of polymerization 400)
12 parts abrasive (α-alumina, average particle size 0.3 μm) 5 parts carbon black (average particle size 40 nm) 2 parts methyl ethyl ketone 300 parts Magnetic field orientation was performed using a 3000 Gauss magnet, and after drying, supercalender treatment was performed, a compound solution was top coated using a bar coater, and the film was slit into an 8M width to produce an 8m videotape. (Sample N
(119-20) The videotape obtained as described above was attached to a VTR (Fuji Photo Film (m: FUJIX-8)).
A 7 MHz signal was recorded and played back using a 7 MHz signal. The 7MHz playback output recorded on the reference tape (comparative example 1) is OdB.
The relative playback output of the videotape was measured when

The obtained videotape and a stainless steel pole are brought into contact (wrapping angle 180°) with a tension of 50g (T1), and under this condition, the required amount is Tension (T2) was measured. Based on this measured value, the friction coefficient μ of the videotape was determined using the following calculation formula.

(Listed in Table 2) μm1/π・1 n (T2 /TI) The friction coefficient test was a, 20℃, 70%RH, b, 40℃1
The experiment was carried out under two conditions: 80% RH.

In addition, the difference in output before and after running was measured after running 100 times, and the result was evaluated as "output decrease."

For head attachment, use the same VTR as above at 23°C.
The video head was observed under a microscope at 100x magnification after running 100 passes at IO%RH.

A: No head adhesion B: Adhesion covering less than 5% of the head area C: Adhesion covering 5% or more of the head area Jitter is the same VT as above
The output when running using R was measured using a jitter meter (black and white radio wave (manufactured by Kiki)).

Binder■ A Polyester polyurethane (weight average molecular weight 40,000, number average molecular weight 2.5 million, polar groups So, Na) B Polyester polyurethane (weight average molecular weight 40,000, number average molecular weight 2.5 million, polar groups P Os Hz ) C Polyester polyurethane (weight average molecular weight 56,000, number average molecular weight 30,000, polar groups NHt ) D Polyester polyurethane (weight average molecular weight 55,000, number average molecular weight 30,000, polar groups OPO, NaH) E Polyester polyurethane (weight average molecular weight 40,000, number average molecular weight 2.5 million, polar group 0H) F Polyether polyurethane (weight average molecular weight 40,000, number average molecular weight 2.5 million, polar group -08O,K) Binder ■ G Vinyl chloride copolymer (average degree of polymerization 400, polar groups epoxy group, So, K) H Vinyl chloride copolymer (average degree of polymerization 350, polar groups -0SO, K) ■ Vinyl chloride/vinyl acetate/maleic anhydride Copolymer (average degree of polymerization 400) J Vinyl chloride copolymer (average degree of polymerization 400, polar group
POsH2) K Vinyl chloride copolymer (average degree of polymerization 400, polar group NH2) L Vinyl chloride/vinyl acetate/vinyl alcohol copolymer (average degree of polymerization 400) Higher fatty acid a Stearic acid b Hexadecanoic acid C Arachidic acid d Behenic acid e Montanic acid higher fatty acid ester g Butoxyethyl stearate h Butyl stearate i 2-ethylhexyl myristate j Isotridecyl stearate k Diethylene glycol monobutyl ether stearate l Glycerin tristearate As is clear from the results in Tables 1 and 2 , of the present invention,
Samples using fatty acids, fatty acid esters, and fluorine-containing silane compounds flk2-4.6-8, lO-15, ■9
It can be seen that the reproduction output is high in all cases of No. 20 to No. 20, and the friction coefficient is low under both conditions a and b, and no decrease in output occurs.

On the other hand, when only fatty acids or esters are used without using the compound of the present invention, or when other fluorine-based lubricants are used, the regeneration output is low, especially under high temperature and high humidity (condition b). It can be seen that there are many problems such as a large coefficient of friction and a decrease in output.

Claims (2)

[Claims] (1) In a magnetic recording medium in which a magnetic layer in which ferromagnetic powder is dispersed in a binder is provided on a non-magnetic support, at least one of the resins accounting for 5% by weight or more of the binder is an epoxy resin. group, -COOM, -SO_3M, -OSO
_3M, -PO_3M_2, -OPO_3M_2, -N
R_2, ▲There are mathematical formulas, chemical formulas, tables, etc.▼(Here, M
represents hydrogen, alkali metal, ammonium, R represents an alkyl group, and X represents a cationic residue) at a rate of 1 x 10^-^7 to 1 x 10^-^ per 1 g of polymer.
3 equivalents, and the magnetic layer contains a fluorosilane compound represented by the following general formula, a higher fatty acid, and a higher fatty acid ester. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ R^1: Monovalent hydrocarbon group with 1 to 6 carbon atoms R^2: Saturated or unsaturated monovalent hydrocarbon group with 7 to 21 carbon atoms m: 1 to 12 l: 1-20 n: 0-2 (2) The magnetic layer contains a fluorosilane compound, a fatty acid, and a fatty acid ester in a weight ratio of 0.1 to 2.0:0.2 to 1.5.
The magnetic recording medium according to claim 1, characterized in that the magnetic recording medium contains: 0.2 to 1.5.