JP3317569B2 - Magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium in which a ferromagnetic metal thin film is formed on a support, and more particularly to a magnetic recording medium in which a protective layer having a rust-proof function and a lubricating function is formed on a ferromagnetic thin film. And a magnetic recording medium having a lubricating layer containing an organic fluorine compound on a magnetic layer.

[0002]

2. Description of the Related Art On a magnetic recording medium such as a magnetic tape, a floppy disk or the like, a coating liquid in which a ferromagnetic powder is dispersed in a composition comprising a lubricant, a dispersant, a binder and the like is coated on a support. In addition to the above magnetic recording medium, a metal thin film type magnetic recording medium in which a ferromagnetic metal thin film is formed on a nonmagnetic support by a vacuum film forming method such as vacuum deposition, sputtering, or ion plating is used.

[0003] With the advent of the Hi-Vision system and technological trends such as digitization of the recording system, in recent years, the demand for high-density recording on magnetic recording media has been increasing. cobalt,
The above-mentioned metal thin-film type magnetic recording medium having a ferromagnetic thin film made of a ferromagnetic metal such as nickel or an alloy thereof as a magnetic layer is similar to a coating type magnetic recording medium except that a magnetic material such as a binder is contained in the magnetic layer. It is most suitable as a magnetic recording medium for high-density recording because it does not contain the above substances. However, the metal thin film type magnetic recording medium has a problem in storage stability because the surface of the metal thin film is easily corroded, and the corrosion adversely affects the electromagnetic conversion characteristics, and has a problem in storage stability. There is a practically fatal defect that the durability and durability are not sufficient, which is a problem. In particular, with the spread of VTRs, it has come to be used in various environmental conditions,
Prevents metal thin film corrosion in high temperature and high humidity environments,
There is an increasing need to consider storability under harsh environmental conditions.

On the other hand, with respect to the running property and durability, it is effective to form a lubricant layer containing a fluorine compound on the surface of the metal thin film. In particular, a compound having a polar group is strongly bonded to the surface of the magnetic layer. Therefore, it was effective to form a stable layer as a lubricating protective layer. It is well known that an organic fluorine compound containing a perfluoroalkyl group has both hydrophobicity and oleophobic properties, and also exhibits properties as a surfactant in water and oil. In addition, they also have the property of lowering surface energy, and by using these properties, an organic fluorine compound is applied to improve the slipperiness and lubricity of the material.

[0005] For example, a lubricant having -COCO- and -SS- at the center of a perfluoropolyether chain is described in JP-A-3-102614, and these include -COCO- and -SS-. Therefore, there is a problem that the magnetic recording medium and the thin film head are easily corroded. Japanese Patent Application Laid-Open No. 64-723 discloses forming a monolayer of a perfluoroalkyl group-alkyl group-polar group on a ferromagnetic metal thin film.
As described in JP-A No. 13, the production of a monomolecular film using a Langmuir blow jet (LB) film was poor in productivity, and was further inferior in μ value (coefficient of friction), still durability, and storage stability.

[0006] Japanese Patent Publication No. 3-19602, JP-A-54
The -79366 _{discloses, -SO 3 Na, -SO 3 K} ,
It describes a lubricant composed of a fluorinated hydrocarbon compound having —SO ₃ H, —COOH, etc., but has a μ value,
Still durability and storage were not sufficient.
Also, JP-A-3-241524 and JP-A-62-9
No. 2227 describes that a compound having a fluoroalkyl group and an aliphatic alkyl group is coated on a ferromagnetic metal thin film. However, these compounds can be coated with isopropanol by introducing an alkyl group. However, the μ value, still durability, and storage stability were still insufficient.

[0007] In addition to applying the above lubricant to the magnetic recording layer, for example, perfluoroalkyl polyether and its derivatives (JP-A-60-61918, JP-A-6-61918)
No. 1-107528, U.S. Pat. No. 3,778,308, Japanese Patent Publication No. 60-10368, U.S. Pat.
No. 897211), however, these fluorine-based organic compound lubricants have a high low-speed coefficient of friction with a partner member on which the tape slides and have an insufficient storage property. Also, the corrosion of acidic gas such as sulfurous acid gas caused the magnetic layer to separate, and it could not be a magnetic recording medium that could withstand practical use.

Many of the above lubricants do not dissolve in ordinary hydrocarbon-based organic solvents such as acetone, methyl ethyl ketone, ethyl acetate, alcohols, and toluene, and use fluorine-based organic solvents for coating. Needed. However, the fluorine-based organic solvent is expensive, and causes a problem of destruction of the ozone layer and deteriorates the working environment, so that it is extremely unsuitable for production.

Further, with respect to corrosion, fluorine compounds are not sufficient, and those having polar groups introduced are not preferred. In particular, a substance having a strong polarity such as a sulfone group and a strong adsorption property to a ferromagnetic metal thin film tends to be unfavorably resistant to corrosion. As a means of preventing rust of a ferromagnetic metal thin film, there is a method of forming an oxide thin film on a ferromagnetic metal thin film. However, while reducing magnetic properties, the distance between the magnetic head and the magnetic layer is increased, so-called spacing. There is a problem that the electromagnetic conversion characteristics are also reduced due to the loss.

Therefore, various methods using a lubricant and a rust inhibitor in combination have been proposed. For example, JP-A-61-8232
No. 4 discloses a ferromagnetic metal thin film type magnetic recording medium using a compound having a mercapto group as a rust inhibitor,
Compounds such as thiophenol and thiouracil are mentioned, and it is also described that a fluorine-based surfactant or the like is used in combination with the rust preventive agent layer as a lubricant. Sufficient rust prevention effect could not be obtained.

Japanese Patent Application Laid-Open No. 61-82325 describes forming a rust preventive layer of a nitrogen-containing heterocyclic compound such as benzotriazole on the surface of a ferromagnetic metal thin film containing cobalt as a main component. However, the antirust effect is not sufficient, and no description is given of the synergistic effect with a lubricant.

JP-A-58-194133 discloses a magnetic recording method in which a rust preventive layer comprising a compound having a heterocyclic ring containing at least one nitrogen atom and a phenolic hydroxyl group is formed on a ferromagnetic metal thin film containing oxygen. The medium is described, and pyridyl azoresorcin, pyridyl azonaphthol, quinolinol, quinoline diol, and kynurenic acid are specifically disclosed as rust preventives, but these compounds have a sufficient rust preventive effect, running property, and durability. Could not be secured.

JP-A-58-194135 describes that a rust inhibitor having a heterocyclic ring containing at least one nitrogen atom is attached to an oxygen-containing ferromagnetic metal thin film. There is no description of using a compound having a group or a fluorine-based lubricant in combination.

JP-A-61-284822 describes a magnetic recording medium in which an oxide film is formed on the surface of a ferromagnetic metal thin film, and a protective layer containing triazinedithiol is further formed thereon. It does not describe the antirust effect or the use of a fluorine-based lubricant in combination.

JP-A-58-189835 describes that a rust preventive adsorption layer is provided on a ferromagnetic metal thin film and a lubricant layer is provided on the adsorption layer. Specific examples include alkylamines, alkyl phosphates, dihydric phenols, diaryl ketones, alkyl phenols, naphthols, quinones, nitroso compounds, and the like. Could not. In addition, fatty acids,
Fluorinated surfactants such as fatty acid esters, fatty acid amides, perfluoroalkylcarboxylic acids and sulfonic acids, and perfluoroalkyl fatty acid esters are disclosed, but no sufficient friction reducing effect was obtained.

When a rust preventive and a fluorine-based lubricant are used in combination, there is a problem that their functions cannot be sufficiently exhibited because they mutually inhibit adsorption on a metal thin film. JP-A-3-141017 discloses a method for obtaining a magnetic recording medium excellent in both running properties and durability by using a compound obtained by introducing a fluorine-containing substituent into a benzotriazole compound as a protective layer of a ferromagnetic metal thin film. Is disclosed.
However, with the compounds disclosed therein, the reduction in the coefficient of friction was not yet sufficient, and the storage stability under conditions of high temperature and high humidity was not sufficient. This is because the fluorine-containing substituent is a perfluoropolyether, so that the orientation of the molecule on the magnetic layer is low, or the introduction position of the substituent is directly connected to the nitrogen atom, so that the structure is unstable. It is thought that it is.

As described above, the running property and durability, which are problems in practical characteristics of a metal thin film magnetic recording medium having a ferromagnetic metal thin film as a magnetic layer, which is optimal as a magnetic recording medium for high density recording, are improved. At the same time, no effective means for improving the storage stability has yet been proposed.

[0018]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned problems of the prior art, and has been developed in view of the running property of a metal thin film type magnetic recording medium.
To provide a thin-film metal-type magnetic recording medium with excellent durability and storability, fully exhibit the high-density magnetic recording characteristics and compactness of the thin-film metal-type medium, and provide a high-density magnetic recording medium. is there.

[0019]

An object of the present invention is to provide a magnetic recording medium having a ferromagnetic metal thin film on at least one surface of a non-magnetic support, wherein the ferromagnetic metal thin film has
A heterocyclic compound containing at least one of a nitrogen atom and a sulfur atom, wherein the heterocyclic ring has a fluorine-containing substituent (excluding a perfluoropolyether group), and further has an --OH group and an --SH group This is achieved by a magnetic recording medium characterized in that there is a layer made of a compound having at least one of the above.

The heterocyclic compound of the present invention includes, for example, thiouracil derivatives (1), thiazole derivatives (2), benzothiazole derivatives (3) and imidazole derivatives represented by the following general formulas (1) to (6): It is preferably at least one compound selected from (4), a benzimidazole derivative (5) and a tetrazaindene derivative (6). Among them, preferred compounds are a thiouracil derivative and a tetrazaindene derivative. These compounds have a high affinity for the magnetic layer, have excellent covering properties on the surface of the magnetic layer, and are preferable in improving the weather resistance.

In these compounds, the introduction position of the fluorine-containing substitution group R is not particularly limited. However, from the viewpoint of ease of synthesis, the thiouracil derivative (1) is located at the 4-position. It is preferable that the thiazole derivative (2) is located at the 4-, 5-position, and the benzothiazole derivative (3) is located at the 4-, 5-, 6-, and 7-positions. Preferably, in the imidazole derivative (4), it is preferably in the 4-position and 5-position, and in the benzimidazole derivative (5), the 4-, 5-, 6-,
It is preferably at the 7-position, and in the tetrazaindene derivative (6), it is preferably at the 5- and 6-positions.

[0022]

Embedded image

The above-mentioned heterocyclic compound in the magnetic recording medium of the present invention is easily adsorbed on the surface of the ferromagnetic metal thin film, and prevents the magnetic layer, which is a trigger of corrosion, from covering the active portion against rust on the ferromagnetic metal thin film. Has a rust effect. In addition, the anti-rust effect is higher than that of a conventionally known heterocyclic compound having no fluorine substituent. This is because the fluorine-containing substituent has water and oil repellency, and water, oxidizing gas, and corrosive gas that enter from the outside by blocking around the active point on the magnetic layer on which the heterocyclic ring is adsorbed and coated. Since it acts as a barrier against other substances, corrosion resistance is further improved.

The presence of the fluorine-containing substituent on the magnetic layer has the effect of reducing the coefficient of friction. In particular, the effect of improving the durability against high-speed sliding with the magnetic recording head is remarkable. As described above, in the magnetic recording medium of the present invention,
Because it has a part with rust prevention effect and lubrication effect in one molecule, compared with the case where a conventional rust inhibitor and a fluorine-based lubricant are mixed and used, the rust prevention effect and A great effect can be obtained with both the coefficient of friction.

In particular, durability against repeated high-speed sliding, specifically, head dirt and head clogging are remarkably improved.

Furthermore, because of the high barrier property against water as described above, the durability in an environment of high humidity can be extremely improved.

The heterocyclic compound of the present invention is characterized by its molecular structure in that it comprises a heterocyclic moiety and a fluorine-containing substituent moiety.

And a thiouracil derivative, a thiazole derivative, in which the heterocycle has either nitrogen or sulfur,
A benzothiazole derivative, an imidazole derivative and a benzimidazole derivative, in which a heterocyclic moiety is strongly adsorbed to an active site where rust is generated, and exhibits a rust preventive effect.

That is, it is considered that such a heterocyclic ring is likely to be strongly bonded to the surface of the ferromagnetic metal thin film because the electron density of π electrons and nitrogen atoms is high.

Further, since the heterocyclic ring contains at least one of -OH group and -SH group, the adsorptivity to the ferromagnetic metal thin film is higher, and the adsorbability of the heterocyclic compound to the ferromagnetic metal thin film is improved. Is increasing.

The fluorine-containing substituent has 5 to 2 carbon atoms.
0, preferably 10-18. If the number of carbon atoms is too small, lubricity is reduced and the rust prevention effect is also reduced. Conversely, when the number of carbon atoms increases, the solubility in a solvent decreases, which is also not preferable.

The number of fluorine atoms of the fluorine-containing substituent is 5 to 5.
25, preferably 7-20.

When the number of fluorine atoms is small, lubricity, durability and corrosion resistance are reduced. On the other hand, if the amount is too large, the solubility in a non-fluorinated ordinary solvent is reduced, which is not preferable.

The fluorine-containing substituent (R) of the heterocyclic compound in the present invention does not include perfluoropolyether. Specifically, other than the perfluoropolyether _{F (CH 2) n (CH} 2) m (X) k (CH 2) p - or _{(CF 3) 2 CF (CF} 2) l (CH 2) m - (X is a divalent linking group).

If the fluorine-containing substituent is perfluoropolyether, the molecular orientation on the ferromagnetic metal thin film is not sufficient due to the presence of an ether bond or the high mobility of the molecular chain, and the friction coefficient is reduced. It is not preferable because the effect is small. Further, the perfluoropolyether group is not preferable because the molecular chain is difficult to be oriented due to a large number of ether bonds and the effect of reducing the friction coefficient is not so high.

It is desirable that the fluorine-containing substituent has a hydrocarbon chain because it is easily dissolved in ordinary solvents other than fluorine-based solvents, which have many problems in environmental protection. Further, among the fluorine-containing substituents, -COO-, -OCO-, -CON
The presence of a linking group X such as H-, -O- or the like has the advantage that the chain length can be easily controlled in the synthesis, but is not necessarily required in the present invention.

On the other hand, (CF ₃ ) ₂ CF (CF
_{2) l (CH 2) m} - weather resistance can increase the fluorine atom density in the ferromagnetic metal thin film surface is a perfluoroalkyl group which is branched at the molecular ends, the durability can be further improved as. As the fluorine-containing substituent, specifically, (C
_{F 3) 2 CF (CF 2} ) 5 (CH 2) 2 -, (CF 3) 2 CF
_{(CF 2) 5 (CH 2} ) 4 -, (CF 3) 2 CF (CF 2)
_{5 (CH 2) 8 -,} (CF 3) 2 CF (CF 2) 3 (CH 2) 2
−, (CF ₃ ) ₂ CF (CF ₂ ) ₃ (CH ₂ ) ₄ −, (C
F ₃ ) ₂ CF (CF ₂ ) ₃ (CH ₂ ) ₈ — and the like. Among them _{(CF 3) 2 CF (CF} 2) 5 (CH 2) 8 -, (C
F ₃ ) ₂ CF (CF ₂ ) ₃ (CH ₂ ) ₈ -has excellent solubility in non-fluorinated solvents, and provides a magnetic recording medium having excellent characteristics in terms of friction coefficient and still durability. This is particularly preferred because

The heterocyclic compound used in the magnetic recording medium of the present invention may have a structure in which the fluorine-containing substituent is directly bonded to a nitrogen or sulfur-containing heterocyclic ring and thus is provided on the magnetic layer.
It is thought that the friction and wear characteristics are improved because the fluorine-containing substituent faces outward. In particular, since it is considered that it is adsorbed on the magnetic layer like the polar group-containing fluorine compound, it is unlikely to be peeled off from the magnetic layer even when sliding at high speed with the magnetic head. Excellent. Furthermore, in the case of a polar group-containing fluorine compound,
Since it has no corrosion resistance by itself, and in some cases shows the corrosive property due to the action of a polar group, it was necessary to use a rust inhibitor in combination. In this case, the rust inhibitor and the adsorption site on the magnetic layer compete with each other, and the effects of both become insufficient, and the fluorine compound that has failed to be adsorbed is repeatedly run because it exists in a free state. In some cases, the magnetic head may be stained, leading to a decrease in output.

In the present invention, as described above, the heterocyclic compound has both a rust-preventing function and a lubricating function and is relatively firmly adsorbed on the magnetic layer, so that the effect can be obtained with a small amount. Can be reduced. In the magnetic recording medium of the present invention, materials having various lubricating functions and corrosion-resistant functions can be used in addition to the heterocyclic compound.

Among them, when the following fluorine compounds are used in combination, the water repellency of the ferromagnetic metal thin film can be further increased, the weather resistance can be improved, and furthermore, from the slit end in the slit step in the production of a magnetic recording medium. This also has the effect of preventing cracks from occurring on the surface of the thin film.

Fluorine compounds which can be used in combination with the heterocyclic compound include carboxylic acids, alcohols and ammonium salts having a perfluoroalkyl group, carboxylic acids, alcohols and ammonium salts having a perfluoroalkylalkylene group, CF _3- (CFR _f CF ₂ -O) _n -C
A perfluoropolyether represented by F ₂ CF ₃ , particularly one whose terminal is modified with a carboxyl group, a hydroxyl group, or the like is preferable, wherein R _f is CF ₃ or F, and the molecular weight is 1,000 to 20,000, preferably 2,500. Or 1
0000, Krytox K143AZ, Krytox K157FSL (manufactured by DuPont), FOMBL
IN AM2001 (manufactured by Montefluos), DEMN
UM SY (manufactured by Daikin Industries, Ltd.) and the like.

Further, perfluoroalkyl carboxylate described in JP-A-62-236119, and fluorine having a lipophilic portion and a hydrophilic portion having a specified length ratio described in JP-A-53-57004. Compound, JP-A-55-
No. 144079, fluorine-based cations and amphoteric surfactants, JP-A-58-29147, polar-group-containing fluorine-containing hydrocarbons, JP-A-61-2
No. 53634, a perfluoro compound having a hydrophilic group bonded thereto, a fluorinated compound comprising a semifluoro compound and a perfluoropolyether described in JP-A-63-281218, and a JP-A 64-71313. And fluorine-containing compounds comprising a monolayer of a polar group-containing perfluoroalkyl group, and perfluoroalkylcarboxylic acids described in JP-A-2-199621.

As the material of the ferromagnetic metal thin film in the present invention, iron, cobalt, nickel or other ferromagnetic metals or Fe-Co, Fe-Ni, Fe-Rh, Co-P, C
o-B, Co-Y, Co-La, Co-Ce, Co-P
t, Co-Sm, Co-Mn, Co-Cr, Co-N
i, Fe-Co-Ni, Co-Ni-P, Co-Ni-
B, Co-Ni-Ag, Co-Ni-Nd, Co-Ni
-Ce, Co-Ni-Zn, Co-Ni-Cu, Co-
A ferromagnetic alloy such as Ni-W or Co-Ni-Re is formed by a vapor deposition method.
μm, particularly preferably 0.05 to 1.0 μm.

The above-mentioned ferromagnetic metal thin films include oxygen, nitrogen, chromium, gallium, arsenic, strontium, zirconium, niobium, molybdenum, rhodium, palladium,
Tin, antimony, tellurium, promethium, rhenium,
It may contain osmium, iridium, gold, mercury, lead, magnesium, bismuth, and the like. As the ferromagnetic metal thin film, of the above, Fe, Co, Co-Ni and the like are desirable. These ferromagnetic metal thin films may be a single layer or may have a multilayer structure of two or more layers for the purpose of improving electromagnetic conversion characteristics.

The non-magnetic support used in the present invention includes plastics such as polyethylene terephthalate, polyimide, polyamide, polyvinyl chloride, cellulose triacetate, polycarbonate, polyethylene naphthalate and polyphenylene sulfide, aluminum, titanium, stainless steel, and the like. Glass or the like can be used.

In order to improve running durability, providing fine projections on the surface of the non-magnetic support before forming the ferromagnetic metal thin film results in providing appropriate irregularities on the surface of the magnetic layer. It is effective. The density of the fine protrusions on the surface of the nonmagnetic support is 2 × 10 ⁶ to 2 × 10 ⁸ , and the height of the protrusions is preferably 1 to 50 nm. The thickness of the nonmagnetic support varies depending on the application, but is generally 3 to 50 μm.

In order to enhance the adhesion of the ferromagnetic metal thin film, an intermediate layer may be provided between the non-magnetic substrate and the ferromagnetic metal thin film.

Further, in order to enhance the running property of the magnetic recording medium of the present invention, a fine powder such as carbon black and a binder resin are mainly formed on the surface of the non-magnetic support opposite to the surface on which the magnetic recording layer is formed. A back coat layer composed of a coating film of

As the binder resin for the back coat layer, those having a composition using a resin such as a vinyl chloride resin, a nitrocellulose resin, a polyurethane resin, a polyester resin, a polyisocyanate resin and, if necessary, a polyisocyanate curing agent are used. Can be used.

In order to apply the heterocyclic compound on the ferromagnetic thin film in the magnetic recording medium of the present invention, the compound may be dissolved in an organic solvent and applied with a coil bar or the like. When the fluorine-containing substituent has a hydrocarbon group in the molecule, the heterocyclic compound can be dissolved not only in a fluorocarbon solvent but also in a normal organic solvent such as acetone, alcohol, and tetrahydrofuran. There is no danger of causing problems such as environmental pollution due to the use of this.

The coating amount of the heterocyclic compound in the present invention is preferably 0.1 to 50 mg / m ² .
Particularly preferably, it is 0.3 to 30 mg / m ² . In the magnetic recording medium of the present invention, it is possible to further improve running durability by providing a back coat layer which is a coating film mainly composed of non-magnetic particles and a binder resin on the surface opposite to the surface where the magnetic layer is located. it can. In the case of a tape medium, the depletion of the material in the magnetic layer can be compensated for by including a lubricating material in the back coat layer and supplying the material to the magnetic layer from a wound state.

An inorganic protective film such as cobalt oxide, silica, alumina, titanium carbide and titanium nitride or a carbon protective film such as amorphous carbon, graphite and diamond is provided on the ferromagnetic metal thin film of the magnetic recording medium of the present invention. Is also good.
The effect of the lubricating layer according to the present invention is further added to the protective action of the protective film, and it sufficiently withstands sliding with the magnetic head under severe conditions, and has no abrasion on the medium surface and has a lubricity on the surface. A magnetic recording medium that can be held for a long time can be obtained.

As the protective film, a carbon protective film is preferable because abrasion powder hardly occurs during sliding and its effect is stably maintained. The carbon protective film is a carbon film formed of an amorphous, graphite, diamond structure or a mixture thereof formed by a plasma CVD method, a sputtering method, or the like, and is particularly preferably a hard carbon film generally called diamond-like carbon. The thickness of such a protective film is preferably 5 to 30 nm, and more preferably 5 to 15 nm.

The synthesis examples of the heterocyclic compound of the present invention are shown below.

Synthesis Example 1 Compound A To 400 ml of dehydrated ethanol was added 23 g of Na. this
CH inside_ThreeCOCH_TwoCOOC_TwoH_Five150 g is dropped
Concentrate under reduced pressure on a water bath to completely remove ethanol.
I left. Then, add 750 ml of dehydrated benzene and stir.
While maintaining the temperature at 30 ° C._ThreeF₇C_TwoH_FourCOCl
Was added. After checking that it has completely dissolved,
The mixture was heated to 45 ° C. and stirred for 3 hours. Next, with Na15g
Na methylate consisting of 150 ml of dehydrated methanol was added.
And stir at 30 ° C for 20 hours.
And stirred at 50 ° C. for 1.5 hours and then cooled.
Extract, dehydrate and add 1,000 ml of benzene.
After distilling off nzen, C _ThreeF₇C_TwoH_FourCOCH_TwoCOO
C_TwoH_Five(I) was obtained. 4.6 g of dehydrated methanol 2
Thiourea S = C (NH_Two)_Two1
5.2 g was added and heated to dissolve. Further, the above (I)
And the mixture is refluxed for 5 hours. Cooled precipitate
Take out the crystals, dissolve in water, add 15 ml of acetic acid and crystallize again.
The compound A described in Chemical Formula 3 was obtained by precipitation.

[Synthesis Example 2] Compound B In Synthesis Example 1, C ₃ F ₇ C ₂ H ₄ COCl was replaced with C ₈ F ₁₇ C ₂
Compound B described in Chemical Formula 3 was obtained by performing synthesis under the same conditions as in Synthesis Example 1 except that H ₄ COCl was used.

[Synthesis Example 3] Compound C 'described in Chemical Formula 3 15 g dissolved in pyridine 50 ml
And then C_ThreeF₇C _FourH₈0.1 ml of OH, paratle
0.01 ml of enesulfonic acid was added. While continuing stirring
DCC (dicyclohexylcarbodiimide) 0.1 m
was dissolved in 50 ml of DMF (dimethylformamide).
The solution was added dropwise, the temperature was raised to 70 ° C., and the mixture was stirred for 4.5 hours.
Was. To this was added 100 ml of acetonitrile to remove crystals.
I started. The crystal was added to 50 ml of DMF and acetonitrile.
After heating and dissolving in 150 ml of mixed solvent, cool and recrystallize
Compound C described in Chemical formula 3 was obtained.

[0058] In Synthesis Example 4 Compound D Synthesis Example 3, in place of the _{C 3 F 7 C 4 H 8} OH, C 3 F 7
Compound C described in Chemical formula 3 was obtained using C ₂ H ₄ OH.

Synthesis Example 5 Compound E Compound E described in Chemical Formula 3 was obtained by using Compound E ′ described in Chemical Formula 3 in Synthesis Example 3 in place of C ₃ F ₇ C ₄ H ₈ OH. .

[0060]

Embedded image

[Synthesis Example 6] A solution in which 7.5 g of C ₃ F ₇ C ₂ H ₄ COCl was dissolved in 15 ml of pyridine was dissolved in a solution of ₄ g of compound F ′ described in compound 4 in 50 ml of pyridine. The mixture was added dropwise with ice cooling and stirring. At this time, stirring was continued for 3 hours while maintaining the temperature at 10 ° C. or lower. Next, the crystals were precipitated and washed with water / methanol, and the crystals were taken out to obtain Compound F described in Chemical Formula 4.

[Synthesis Example 7] Compound G In Synthesis Example 6, C ₈ F was used instead of C ₃ F ₇ C ₄ H ₈ OH.
Compound G described in Chemical Formula _{4 was obtained by} replacing _{17 ′} C ₂ H ₄ COCl with Compound G ′ described in Chemical Formula 3 for F ′.

[Synthesis Example 8] Compound H In Synthesis Example 6, C ₈ F was used instead of C ₃ F ₇ C ₄ H ₈ OH.
Compound C described in Chemical Formula 4 was obtained by replacing _{17 ′} C ₂ H ₄ COCl with Compound H ′ described in Chemical Formula 3 for F ′.

[0064]

Embedded image

[Synthesis Example 9] In the synthesis example 1, C ₃ F ₇ C
Compound I described in Chemical Formula 4 was obtained by replacing ₂ H ₄ COCl with CF ₃ C ₃ H ₆ COCl.

[0066]

The novel features of the present invention will be described more specifically in the following examples.

[Examples and Comparative Examples] A 150 nm thick CoN was formed on a 10 μm thick polyethylene terephthalate.
An i-alloy magnetic film was obliquely deposited to form a ferromagnetic metal thin film. As the evaporation source, an electron beam evaporation source was used, and a cobalt-nickel alloy (Co: 80% by weight, Ni: 20% by weight) was charged into the evaporation source at a degree of vacuum of 6.7 × 10 ⁻³ N / m ² . Oblique deposition was performed while introducing oxygen gas so that the incident angle was 50 degrees. The compounds shown in Tables 1 and 2 were applied to the obtained ferromagnetic metal thin film in a methyl ethyl ketone solution, coated with a coil bar, dried, and applied on the ferromagnetic thin film in a predetermined amount. As a solvent for the fluorine compound of the comparative example, a Freon 113 solution was used. A back layer was provided on the back surface of the support, and slit into 8 mm width to prepare a magnetic tape. The obtained magnetic tape was evaluated by the following methods, and the results are shown in Tables 1 and 2.

[0068]

Embedded image

[Evaluation Method] Measurement of Friction Coefficient (μ Value) The obtained magnetic tape and stainless steel pole were contacted at a winding angle of 180 ° with a tension (T ₁ ) of 30 g, and the magnetic tape was 3.3 cm / sec. Measure the tension (T ₂ ) required to run at the speed of
The friction coefficient μ was determined. μ = 1 / π · ln (T ₂ / T ₁ ) The friction coefficient is as follows: Condition A: as it is (before storage) and B
Conditions: Those stored for 7 days in an environment of 60 ° C. and 90% RH were measured at 23 ° C. and 70% RH, respectively.

Measurement of Still Durability Still durability was measured using an 8 mm VTR for Hi-8 (FUJIX FX-100 manufactured by Fuji Photo Film Co., Ltd.) in the still state without operating the still limit mechanism. The time until the image disappeared was measured and evaluated. Still durability was measured at 5 ° C. and 10% RH for condition A: as is (before storage) and condition B: for 7 days stored in an environment of 60 ° C. and 90% RH. The case where there was no time of 30 minutes or more was indicated by "O".

Evaluation of Weather Resistance The magnetic layer was stored in the following environment and the surface of the magnetic layer after storage was observed visually and by an optical microscope. Cl ₂ : 10 ppb, NO ₂ : 200 ppb, H ₂ S:
10 ppb Flow rate of the above three types of mixed gas: 1000 liters / hour Temperature and humidity: 60 ° C. 90% RH Storage days: 10 days Evaluation criteria ○ ‥ A level at which no corrosion is observed when the surface of the magnetic layer is observed with a 200 × optical microscope. . △ ‥ As above, corrosion is observed, but metal luster on the surface of the magnetic layer is visually observed. × ‥ The level at which there is no metallic luster on the surface of the magnetic layer when observed with the naked eye.

Output change: The change in output was measured by running a 90-minute long magnetic tape in an environment of 23 ° C. and 70% RH using the same VTR as in the evaluation of still durability.

Instantaneous clogging: Using the same VTR as in the evaluation of still durability, a magnetic tape having a length of 90 minutes was repeatedly run for 100 passes in an environment of 23 ° C. and 70% RH, and the number of occurrences of instantaneous clogging was measured. did. Evaluation criteria ○: 0 times △: 1 to 10 times ×: 10 times or more

[0074]

[Table 1]

[0075]

[Table 2]

[0076]

According to the present invention, there is provided a heterocyclic compound containing at least one of a nitrogen atom and a sulfur atom on a ferromagnetic metal thin film, wherein the heterocyclic ring has a fluorine-containing substituent (excluding a perfluoropolyether group). ), And further, by forming a protective layer comprising a compound having at least one of -OH group and -SH group, excellent corrosion resistance, low friction coefficient, good durability and good effect are obtained. The magnetic recording medium can be maintained even after storage under high temperature and high humidity conditions.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C07D 277/62 C07D 277/62 G11B 5/66 G11B 5/66 (72) Inventor Tsukasa Okita 2--12 Ogimachi, Odawara-shi, Kanagawa No. 1 Fuji Photo Film Co., Ltd. (56) References JP-A-1-302529 (JP, A) JP-A-4-221426 (JP, A) JP-A-61-104319 (JP, A) JP-A-2 -310820 (JP, A) JP-A-62-172527 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 5/725 C07D 235/02 C07D 239/24 C07D 239/70 C07D 277/20 C07D 277/62 G11B 5/66

Claims (3)

(57) [Claims] 1. A magnetic recording medium having a ferromagnetic metal thin film on at least one surface of a nonmagnetic support, wherein a complex containing at least one of a nitrogen atom and a sulfur atom is provided on the ferromagnetic metal thin film. A ring compound, wherein the heterocyclic ring has a fluorine-containing substituent (excluding a perfluoropolyether group), and further has a layer made of a compound having at least one of -OH group and -SH group. A magnetic recording medium characterized by the above-mentioned. 2. The magnetic recording medium according to claim 1, wherein the fluorine-containing substituent is a fluoroalkyl group having 5 to 20 carbon atoms and 5 to 25 fluorine atoms. 3. The compound represented by the following general formula (1):
Thiouracil derivatives (1), thiazole derivatives (2), benzothiazole derivatives (3),
3. The magnetic recording medium according to claim 1, wherein the magnetic recording medium is at least one selected from an imidazole derivative (4), a benzimidazole derivative (5), and a tetrazaindene derivative (6). Embedded image