JPH0896353A - Magnetic recording medium - Google Patents

Abstract

PURPOSE: To reduce the coefft. of friction of a magnetic recording medium even in a severe environment by forming a mixed lubricant layer consisting of a coupling agent and a specified amine salt of fluoroalkylcarboxylic acid on a protective film on a magnetic layer. CONSTITUTION: When a ferromagnetic metallic film 2, a protective film 3 and a lubricant film 4 are laminated on a base film 1 to obtain a magnetic recording medium, a mixed lubricant layer consisting of a coupling agent and an amine salt of fluoroalkylcarboxylic acid represented by formula I, II or III is used as the film 4. The coefft. of friction of the magnetic recording medium can be reduced even in a severe environment such as an environment at a high temp. and humidity or at a low temp. and the objective magnetic recording medium having improved running performance, frictional resistance and durability over a long period of time is obtd.

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 such as a magnetic tape or a magnetic disk, and more particularly to improvement of running property, abrasion resistance and durability.

[0002]

2. Description of the Related Art In recent years, with the increasing demand for high density recording, Co--Ni alloys, Co--Cr alloys, Co--Ni--
A magnetic metal material such as O or Co-O is directly coated on a non-magnetic support such as a polyester film, polyamide, or polyimide film by plating or a vacuum thin film forming means (vacuum deposition method, sputtering method, ion plating method, etc.). A magnetic recording medium of a so-called metal magnetic thin film type in which a magnetic layer is formed by attaching the magnetic recording medium has been proposed and attracts attention.

In particular, an oblique evaporation type magnetic recording medium in which a magnetic layer is formed by obliquely evaporating a metal magnetic material is put to practical use because it has excellent electromagnetic conversion characteristics and a large reproduction output. ing.

By the way, in these metal magnetic thin film type magnetic recording media, since the surface of the magnetic layer is extremely good, the substantial contact area with a sliding member such as a magnetic head or a guide roller is large, and the friction coefficient is large. Grows larger. For this reason, adhesion phenomenon (so-called sticking) with these sliding members
Is likely to occur, and there are many problems such as lack of running performance and durability.

Therefore, the use of various lubricants has been studied in order to improve such problems. For example, attempts have been made to suppress the friction coefficient by internally adding a top fatty acid or its ester as a lubricant to the magnetic layer or by top coating.

By the way, the lubricant used in the magnetic recording medium is required to have extremely strict characteristics, and it is difficult to meet the above-mentioned conventional lubricants at present.

That is, the lubricant used in the magnetic recording medium is (1) excellent in low temperature characteristics so as to ensure a predetermined lubricating effect when used in cold regions, and (2) with a magnetic head. Since the spacing becomes a problem, it is required that the coating can be applied extremely thinly, sufficient lubrication characteristics can be exhibited even in that case, and (3) that it can be used for a long time and the lubricating effect continues.

However, from the above point of view, higher fatty acids and esters thereof, which have been conventionally used as lubricants, impair the lubrication performance under severe conditions such as high temperature and high humidity or low temperature and low humidity, and the tape The running property and wear resistance cannot be sufficiently improved.

Therefore, various studies have been conducted to obtain a lubricant exhibiting sufficient lubricating performance even in a high temperature and high humidity environment or a low temperature and low humidity environment. For example, a silane coupling agent or a titanate having a fluorinated alkyl chain. Coupling agents have been proposed. As an example, a titanate coupling agent having only a perfluoroalkyl chain portion is shown in Chemical formula 6.

[0010]

[Chemical 6]

However, a silane coupling agent or a titanate coupling agent having a fluorinated alkyl chain, represented by the compound represented by the chemical formula 6, is a commonly used organic solvent such as ethanol or hexane. ，
There is a problem that it has a low solubility in toluene and the like and can be dissolved only in a fluorine-based solvent (Freon), which is problematic in terms of global environmental protection.

In addition, as a method for improving the running property and abrasion resistance of the tape, a silane coupling agent containing a fluorine atom is applied to the surface of the medium to form a strong film. It is proposed in Japanese Patent Laid-Open No. 63-220420.

However, in order to bond the silane coupling agent to the surface of the magnetic layer or the surface of the magnetic powder, it is necessary to apply a high temperature of 100 ° C. or higher. For example, the non-magnetic support made of PET film is deformed by this heat treatment. There is an inconvenience that it will end up.

Furthermore, Japanese Patent Laid-Open No. 58-2111325
In JP-A No. 62-112214, a mixture of a perfluoroalkylcarboxylic acid ester and a titanate-based coupling agent is used as a lubricant on the surface of the magnetic layer as a lubricant. It is suggested to be applied.

However, the titanate coupling agent having a long alkyl chain has an insufficient adsorption property to the surface of the magnetic layer, and the structure described in the above publication cannot provide sufficient lubrication property.

Further, a mixture of a perfluoroalkylcarboxylic acid ester and a titanate coupling agent also has a disadvantage that solubility in a solvent is low and sufficient lubricating performance cannot be obtained.

As described above, in the field of magnetic recording media,
Due to lack of ability of lubricant, practical characteristics such as running durability remain unsatisfactory.

Therefore, the present invention has been proposed in view of such a conventional situation, and excellent lubricity is maintained under various usage conditions and the lubricity is maintained for a long time. It is an object of the present invention to obtain a lubricant and provide a magnetic recording medium excellent in running property, wear resistance and durability.

[0019]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies as a means to achieve the above-mentioned object, and as a result, have found that an alkylcarboxylic acid amine salt having a partially fluorinated hydrocarbon group and a titanate coupling agent are used. It has been found that the above lubricant mixture is suitable as a lubricant for magnetic recording media.

The present invention has been completed based on these findings, and is a magnetic recording medium comprising a non-magnetic support and at least a magnetic layer and a protective layer formed on the non-magnetic support.
A mixture of a coupling agent and a partially fluorinated alkylcarboxylic acid amine salt represented by any one of Chemical formula 7, Chemical formula 8, and Chemical formula 9 is deposited on the protective layer. .

[0021]

[Chemical 7]

[0022]

[Chemical 8]

[0023]

[Chemical 9]

In the magnetic recording medium of the present invention, a magnetic layer and a protective film are formed on a non-magnetic support, and a coupling agent and the above chemical formulas 7, 8 and 9 are used as lubricants on the protective film.
And a lubricant mixture with a partially fluorinated alkylcarboxylic acid amine salt represented by

The lubricant mixture of the coupling agent and the partially fluorinated alkylcarboxylic acid amine salt has a good lubricating performance and greatly reduces the friction coefficient between the medium and various sliding members. In addition, this lubricant mixture maintains the lubricating performance even at low temperatures, and the partially fluorinated alkylcarboxylic acid amine salt suppresses the deterioration of the lubricating action of the coupling agent, especially in a hot and humid environment. Act on.
That is, this lubricant mixture sufficiently reduces the coefficient of friction of the medium even in a severe environment such as low temperature and high temperature and high humidity.

Therefore, in a magnetic recording medium using a mixture of the amine salt of partially fluorinated alkylcarboxylic acid and the coupling agent as a lubricant, a complex synergistic effect of the amine salt of partially fluorinated alkylcarboxylic acid and such coupling agent is obtained. Due to the effect, good running property and durability can be obtained under various usage conditions.

In order to obtain the above effects, it is important that the partially fluorinated alkylcarboxylic acid amine salt and the titanate coupling agent have a predetermined structure.

First, as the partially fluorinated alkylcarboxylic acid amine salt, those represented by the above chemical formulas 7, 8 and 9 are used. Thus, even if the alkyl chain partially fluorinated in the partially fluorinated alkyl carboxylic acid amine salt is the alkyl chain of the alkyl amine moiety as shown in Chemical formula 8, the alkyl chain of the alkyl carboxylic acid moiety as shown in Chemical formula 9 However, either may be used. Further, as shown in Chemical formula 7, both the alkyl chain of the alkylamine portion and the alkyl chain of the alkylcarboxylic acid portion may be partially fluorinated.

Here, in order to obtain a good lubricating effect with these partially fluorinated alkylcarboxylic acid amine salts,
It is necessary that the chain length of the alkylamine moiety and the alkylcarboxylic acid moiety be within a predetermined range.

That is, in the compounds represented by Chemical formulas 7 and 8, the carbon number x of the alkyl chain of the alkylamine moiety is 2 to 29, the carbon number y of the fluorocarbon chain is 1 to 28, and x + y.
Is 8 to 30, and in the compound represented by Chemical formula 9, the number x of carbon atoms in the alkyl chain of the alkylamine moiety is 2 to 29.

In the compounds represented by Chemical formulas 7 and 9, the number of carbon atoms u of the alkyl chain of the alkylcarboxylic acid moiety is 2 to 29, the number of carbon atoms v of the fluorocarbon chain is 1 to 28, and u + v.
Is 8 to 30, and in the compound represented by Chemical formula 8, the carbon number u of the alkyl chain of the alkylcarboxylic acid moiety is 2 to 29.

In any of the compounds, when x + y or u + v is less than 8, the intermolecular interaction between the hydrophobic groups becomes relatively weak and the lubricating effect is lost. Conversely, x
If + y or u + v exceeds 30, then the interaction between the hydrophobic groups becomes too strong and the lubricating effect is also impaired. Further, when the total number of carbon atoms of the fluorinated alkyl group is 3 or less, the effect of reducing the surface energy by the fluorine atom and the effect of suppressing the increase of the friction coefficient in a high temperature and high humidity environment are impaired.

On the other hand, as a coupling agent to be mixed with such a partially fluorinated alkylcarboxylic acid amine salt, a titanate coupling agent represented by Chemical formula 10 is suitable.

[0034]

[Chemical 10]

In the titanate coupling agent represented by Chemical formula 10, the number n of (R ₁ -O) -groups bonded to titanium is determined by the valence of titanium. In this case, 1
Or 2. The carbon number m of the alkylcarboxylic acid moiety is 2 to 29. When the value of m is 30 or more, the interaction between the hydrophobic groups becomes too strong and the lubricating effect is impaired. As such a titanate-based coupling agent,
The compound represented by Chemical formula 11 is the most preferable.

[0036]

[Chemical 11]

In order to deposit the lubricant mixture of the partially fluorinated alkylcarboxylic acid amine salt and the titanate coupling agent on the protective film, the lubricant mixture is dissolved in a solvent to prepare a lubricant solution. Is prepared, and this may be top-coated on the surface of the protective film. The mixing ratio of the lubricant mixture in the solution is 0.1: 99.9 to 5 for the partially fluorinated alkylcarboxylic acid amine salt: titanate coupling agent).
It is desirable that the concentration is 0:50, and the concentration is 0.05 to 5 mM, more preferably 0.1 to 3 mM. Further, examples of the solvent include toluene, ethanol, hexane and the like.

As described above, in the present invention, the lubricant mixture of the partially fluorinated alkylcarboxylic acid amine salt and the coupling agent is used as the lubricant, but the non-magnetic support, the magnetic layer,
The following materials are used for the protective film, for example.

First, as the non-magnetic support, any of those usually used in magnetic recording media can be used. For example, polyesters such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose triacetate, cellulose diacetate and cellulose butyrate, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, polycarbonates, polyimides, polyamides. In addition to polymer materials such as, light metals such as aluminum alloys and titanium alloys, ceramics such as alumina glass, and the like. When a rigid substrate such as an aluminum alloy plate or a glass plate is used as the non-magnetic support, an oxide film such as alumite treatment or a Ni-P film is formed on the substrate surface to harden the surface. May be.

The magnetic layer is a metal magnetic thin film formed by depositing a metal magnetic material on a non-magnetic support by a PVD method such as plating, sputtering or vacuum deposition.

Fe, Co, Ni are used as the metal magnetic thin film.
And other metals, Co-Ni-based alloys, Co-Pt-based alloys, C
o-Pt-Ni based alloy, Fe-Co based alloy, Fe-Ni
Examples of the in-plane magnetization recording type metal magnetic film include a Fe-Co-Ni-based alloy, a Fe-Ni-B-based alloy, an Fe-Co-B-based alloy, and a Fe-Co-Ni-B-based alloy. To be Besides, a perpendicular magnetic recording type metal magnetic film made of a Co—Cr alloy or the like may be used.

Of these, in the case of the in-plane magnetization recording type metal magnetic thin film, Bi, Sb, Pb,
An underlayer of a low melting point non-magnetic material such as Sn, Ga, In, Ge, Si, Tl is formed in advance, and a metallic magnetic material is vertically vapor-deposited or sputtered on the underlayer to form a metallic magnetic thin film. It is good to form. When a metal magnetic material is deposited on the underlayer, the low-melting point nonmagnetic material diffuses in the metal magnetic thin film, the orientation of the metal magnetic thin film is eliminated, and the in-plane isotropic property is ensured. Anti-magnetism is improved.

The protective film to which the lubricant is applied is
It is for imparting durability to the medium. Examples of this protective film include a hard protective film such as a carbon film, a diamond-like carbon film, a chromium oxide film, and a SiO ₂ film. Among them, the carbon film is excellent in durability.

The above is the basic structure of the present invention. The magnetic recording medium of the present invention is similar to the ordinary magnetic recording medium.
Further, various elements may be added to further improve the characteristics.

For example, a rust preventive agent may be top-coated with a lubricant on the carbon protective film. Examples of the rust preventive agent that can be used include phenols, naphthols, quinones, nitrogen atom-containing heterocyclic compounds, oxygen atom-containing heterocyclic compounds, and sulfur atom-containing heterocyclic compounds. These rust preventive agents may be used by mixing them with a mixture of a partially fluorinated alkylcarboxylic acid amine salt serving as a lubricant and a coupling agent. Separately from this lubricant mixture, the rust preventive agent is formed on the protective film. A layer different from the lubricant layer of the lubricant mixture may be applied, such as applying the rust preventive agent first and then applying the lubricant mixture.

An undercoat layer may be formed on the surface of the non-magnetic support on which the magnetic layer is formed, or a back coat layer may be formed on the surface opposite to the side on which the magnetic layer is formed. May be. Among these, the back coat layer is formed by adding a carbon-based fine powder for imparting conductivity and an inorganic pigment for controlling the surface roughness to the resin binder and applying the same. The back coat layer may be internally added or top-coated with the above-mentioned lubricant mixture.

[0047]

The magnetic recording medium of the present invention comprises a non-magnetic support,
A magnetic recording medium comprising at least a magnetic layer and a protective layer, wherein the protective layer is coated with a lubricant mixture of a coupling agent and a partially fluorinated alkylcarboxylic acid amine salt having a predetermined structure. There is.

The lubricant mixture of the coupling agent and the partially fluorinated alkylcarboxylic acid amine salt has a good lubricating performance and greatly reduces the friction coefficient between the medium and various sliding members. In addition, this lubricant mixture maintains its lubricating performance even at low temperatures, and particularly, in a high temperature and high humidity environment,
The partially fluorinated alkylcarboxylic acid amine salt acts to prevent the lubricating action of the coupling agent from being impaired. That is, the lubricant mixture sufficiently reduces the friction coefficient of the medium even in a severe environment such as low temperature and high temperature and high humidity.

Therefore, in the above magnetic recording medium using the mixture of the partially fluorinated alkylcarboxylic acid amine salt and the coupling agent as a lubricant, the coupling agent and the partially fluorinated alkylcarboxylic acid amine salt are combined. Due to the synergistic effect, good running performance and durability can be obtained under various usage conditions.

[0050]

EXAMPLES Hereinafter, specific examples of the present invention will be described, but it goes without saying that the present invention is not limited to these examples.

Example 1 In this example, the partially fluorinated alkylcarboxylic acid amine salt and the titanate coupling agent used as the lubricant are shown in Chemical formulas 12 and 13, respectively.

[0052]

[Chemical 12]

[0053]

[Chemical 13]

Of these, the titanate coupling agent is
It is a commercially available product (manufactured by Ajinomoto Co., Inc., trade name KR-TTS), and the partially fluorinated alkylcarboxylic acid amine salt is synthesized by the following method.

<Synthesis of Partially Fluorinated Alkylcarboxylic Acid Amine Salt> Equimolar amounts of CF ₃ (CF ₂ ) ₉ I and H ₂ C = C
H (CH ₂ ) ₈ COOEt was mixed in carbon tetrachloride.
Then, AIBN was added to the carbon tetrachloride solution as an initiator of the radical addition reaction, and refluxed at a temperature of about 100 ° C. for 7 hours. As a result, CF ₃ (CF ₂ ) ₉
CH ₂ CHI (CH ₂ ) ₈ COOEt is produced. This radical addition reaction formula is shown in Chemical formula 14.

[0056]

[Chemical 14]

Next, the generated CF ₃ (CF ₂ ) ₉
CH ₂ CHI (CH ₂ ) ₈ COOEt was dissolved in an acetic acid solution saturated with HCl gas, Zn powder was added, and then refluxed at a temperature of 100 ° C. for 1 hour. This operation was repeated 3 times. As a result, CF ₃
(CF ₂ ) ₉ (CH ₂ ) ₁₀ COOEt is produced. The reaction formula at this time is shown in Chemical formula 15.

[0058]

[Chemical 15]

Then, the generated CF ₃ (CF ₂ )
₉ (CH ₂ ) ₁₀ COOEt is hydrolyzed with alkali to form a partially fluorinated alkylcarboxylic acid CF ₃ (CF ₂ ) ₉ (CH
₂ ) Generated ₁₀ COOH. The reaction formula of this alkaline hydrolysis is shown in Chemical formula 16.

[0060]

[Chemical 16]

Next, a part of the produced partially fluorinated alkylcarboxylic acid is reacted with an acid chloride and ammonia to form an amide CF ₃ (CF ₂ ) ₉ (CH ₂ ) ₁₀ CONH.
Generated ₂ . This reaction formula is shown in Chemical formula 17.

[0062]

[Chemical 17]

This amide CF ₃ (CF ₂ )
₉ (CH ₂ ) ₁₀ CONH ₂ is reduced to give a partially fluorinated alkylamine CF ₃ (CF ₂ ) ₉ (CH ₂ ) ₁₀ CH ₂ NH ₂
Was generated. The reaction formula of this reduction reaction is shown in Chemical formula 18.

[0064]

[Chemical 18]

This partially fluorinated alkylamine CF ₃ (C
F ₂ ) ₉ (CH ₂ ) ₁₀ CH ₂ NH ₂ and the partially fluorinated alkylcarboxylic acid CF ₃ (C
F ₂ ) ₉ (CH ₂ ) ₁₀ COOH was refluxed in ethanol. This reaction formula is shown in Chemical formula 19.

[0066]

[Chemical 19]

After removal of the solvent, recrystallization using hexane was carried out to obtain the target compound of formula 12, that is, a partially fluorinated alkyl compound in which both alkyl chains of the alkylcarboxylic acid moiety and the alkylamine moiety were partially fluorinated. A carboxylic acid amine salt was obtained.

<Preparation of Magnetic Tape> The structure of the magnetic tape prepared in this example is shown in FIG. The magnetic tape shown in FIG. 1 is a polyethylene terephthalate base film 1
A ferromagnetic metal thin film 2, a carbon protective film 3, and a mixed lubricant film 4 of the partially fluorinated alkylcarboxylic acid amine salt and a titanate coupling agent are sequentially formed on the upper surface of the ferromagnetic metal thin film 2. Such a magnetic tape was produced as follows.

Co-Ni was deposited on the 14 μm-thick polyethylene terephthalate base film 1 by the oblique evaporation method to form a ferromagnetic metal thin film 2 having a film thickness of 100 nm.

Then, a carbon protective film 3 having a film thickness of 20 nm was formed on the surface of the ferromagnetic metal thin film 2 by the sputtering method.

Next, on the surface of the carbon protective film 3, a partially fluorinated alkylcarboxylic acid amine salt represented by Chemical formula 12 is formed.
The titanate coupling agent represented by 3 was mixed at a mixing ratio of 1: 2 to prepare a lubricant mixture containing 1 mM in toluene.
A mixed lubricant solution having a certain concentration was applied to form a mixed lubricant film 4, and the mixed lubricant film 4 was cut into 8 mm widths to prepare a magnetic tape.

Example 2 A magnetic tape was prepared in the same manner as in Example 1 except that the mixing ratio of the partially fluorinated alkylcarboxylic acid amine salt and the titanate coupling agent in the mixed lubricant solution was changed to 1: 5. did.

Example 3 The mixing ratio of the partially fluorinated alkylcarboxylic acid amine salt and the titanate coupling agent in the mixed lubricant solution was 1:10.
A magnetic tape was produced in the same manner as in Example 1 except that the above was changed.

Example 4 A magnetic tape was prepared in the same manner as in Example 1 except that the mixing ratio of the partially fluorinated alkylcarboxylic acid amine salt and the titanate coupling agent in the mixed lubricant solution was changed to 1: 1. did.

Example 5 As a partially fluorinated alkylcarboxylic acid amine salt, except that a compound represented by Chemical formula 20, that is, a partially fluorinated alkylcarboxylic acid amine salt in which only the alkyl chain of the alkylcarboxylic acid moiety is partially fluorinated is used. A magnetic tape was produced in the same manner as in Example 1.

[0076]

Embedded image

Example 6 A magnetic tape was prepared in the same manner as in Example 5 except that the mixing ratio of the partially fluorinated alkylcarboxylic acid amine salt and the titanate coupling agent in the mixed lubricant solution was changed to 1: 5. did.

Example 7 The mixing ratio of the partially fluorinated alkylcarboxylic acid amine salt and the titanate coupling agent in the mixed lubricant solution was 1:10.
A magnetic tape was produced in the same manner as in Example 5 except that the above procedure was changed.

Example 8 A magnetic tape was prepared in the same manner as in Example 5 except that the mixing ratio of the partially fluorinated alkylcarboxylic acid amine salt and the titanate coupling agent in the mixed lubricant solution was changed to 1: 1. did.

Example 9 A partially fluorinated alkylcarboxylic acid amine salt is used, except that a compound represented by Chemical formula 21 is used, that is, a partially fluorinated alkylcarboxylic acid amine salt in which only the alkyl chain of the alkylamine moiety is partially fluorinated. A magnetic tape was produced in the same manner as in Example 1.

[0081]

[Chemical 21]

Example 10 A magnetic tape was prepared in the same manner as in Example 9 except that the mixing ratio of the partially fluorinated alkylcarboxylic acid amine salt and the titanate coupling agent in the mixed lubricant solution was changed to 1: 5. did.

Example 11 The mixing ratio of the partially fluorinated alkylcarboxylic acid amine salt and the titanate coupling agent in the mixed lubricant solution was 1:10.
A magnetic tape was produced in the same manner as in Example 9 except that the above was changed to.

Example 12 A magnetic tape was prepared in the same manner as in Example 9 except that the mixing ratio of the partially fluorinated alkylcarboxylic acid amine salt and the titanate coupling agent in the mixed lubricant solution was changed to 1: 1. did.

Comparative Example 1 A lubricant film was formed by coating the surface of the protective film with a single lubricant solution in which only the titanate coupling agent represented by Chemical formula 13 was dissolved at a concentration of 1 mM. A magnetic tape was produced in the same manner as in Example 1.

Comparative Example 2 A lubricant film was formed by coating the surface of the protective film with a single lubricant solution in which only the partially fluorinated alkylcarboxylic acid amine represented by Chemical formula 12 was dissolved at a concentration of 1 mM. A magnetic tape was produced in the same manner as in Example 1 except for the above.

Comparative Example 3 A lubricant film was formed by coating the surface of the protective film with a single lubricant solution in which only the partially fluorinated alkylcarboxylic acid amine represented by Chemical formula 20 was dissolved at a concentration of 1 mM. A magnetic tape was produced in the same manner as in Example 1 except for the above.

Comparative Example 4 A lubricant film was formed by coating the surface of the protective film with a single lubricant solution in which only the partially fluorinated alkylcarboxylic acid amine represented by Chemical formula 21 was dissolved at a concentration of 1 mM. A magnetic tape was produced in the same manner as in Example 1 except for the above.

Comparative Example 5 A mixed lubricant solution in which the alkylcarboxylic acid amine salt represented by Chemical formula 22 and the titanate coupling agent represented by Chemical formula 13 were dissolved in a mixing ratio of 1: 2 on the surface of the protective film. Example 1 except that a lubricant film was formed by applying
A magnetic tape was produced in the same manner as.

[0090]

[Chemical formula 22]

With respect to the magnetic tape manufactured as described above, the friction coefficient, the still durability, the temperature 25 ° C., the humidity 60% environment, the temperature 40 ° C., the humidity 80% environment and the temperature −10 ° C. environment, respectively. The shuttle durability was measured. The still durability was evaluated by measuring the time for the output to decay to -3 dB in the paused state. The shuttle durability was evaluated by repeating the shuttle running for 2 minutes as one shuttle and measuring the number of shuttles until the output decreased by -3 dB. The results are shown in Tables 1 to 4.

[0092]

[Table 1]

[0093]

[Table 2]

[0094]

[Table 3]

[0095]

[Table 4]

In Tables 1 to 4, first, the magnetic tapes of Examples 1 to 12 in which a mixture of a partially fluorinated alkylcarboxylic acid amine salt and a titanate coupling agent were adhered to the surface of the protective film, and the partial Comparing the magnetic tapes of Comparative Example 2 to Comparative Example 4 coated with only the fluorinated alkylcarboxylic acid amine salt, the magnetic tapes of Examples 1 to 12 were compared with Comparative Example 2 under any measurement condition. ~ Comparative Example 4
The magnetic tape has a lower friction coefficient than the magnetic tape, and therefore has excellent still durability and shuttle durability.

Further, comparing the magnetic tapes of Examples 1 to 12 with the magnetic tape of Comparative Example 1 to which only the titanate coupling agent was applied, Example 1 was examined under high temperature and high humidity conditions and low temperature conditions. The friction coefficient of the magnetic tape of Example 12 is lower than that of the magnetic tape of Comparative Example 1. Furthermore, comparing with Comparative Example 5 in which an alkylcarboxylic acid amine salt and a titanate-based coupling agent were adhered,
The magnetic tapes of Examples 1 to 12 have lower friction coefficients under high temperature and high humidity conditions and low temperature conditions.

From the above, a mixture of a partially fluorinated alkylcarboxylic acid amine salt and a titanate coupling agent is suitable as a lubricant, and by using this lubricant mixture, a high temperature and high humidity environment and a low temperature environment can be obtained. Good runnability in various usage environments including. It was found that a magnetic recording medium exhibiting durability can be obtained.

After the above characteristic evaluation, the parameters such as the residual magnetic flux density and the coercive force of the magnetic tape were measured, and it was confirmed that there was almost no change from that before the characteristic evaluation.

Further, in this embodiment, the lubricant is not used in combination with any other material such as a rust preventive, but the same tendency can be obtained even when the rust preventive is used in combination. is there. The same applies when another type of titanate coupling agent is used as the coupling agent of the lubricant mixture or a chromium oxide film, a SiO ₂ film, or a zirconia film is used as the protective film.

[0101]

As is apparent from the above description, in the magnetic recording medium of the present invention, the protective film is formed on the magnetic layer, and the partially fluorinated alkylcarboxylic acid amine having a predetermined structure is further formed on the protective film. Since a mixture of salt and coupling agent is applied, it is possible to obtain excellent running properties, wear resistance, and durability for a long period of time under various operating conditions including high temperature and high humidity and low temperature. is there.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an essential part showing a structural example of a magnetic recording medium to which the present invention is applied.

[Explanation of symbols]

 1 Base film 2 Ferromagnetic metal thin film 3 Protective film 4 Lubricant film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Kawasaku 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (6)

[Claims] 1. A magnetic recording medium in which at least a magnetic layer and a protective layer are formed on a non-magnetic support, and the coupling agent and the chemical formula 1, chemical formula 2, and chemical formula 3 are formed on the protective layer. A magnetic recording medium having a mixture with a partially fluorinated alkylcarboxylic acid amine salt represented by [Chemical 1] [Chemical 2] [Chemical 3] 2. The magnetic recording medium according to claim 1, wherein the coupling agent is a titanate coupling agent represented by Chemical formula 4. [Chemical 4] 3. The mixing ratio of the partially fluorinated alkylcarboxylic acid amine salt and the titanate-based coupling agent (partially fluorinated alkylcarboxylic acid amine salt: titanate-based coupling agent) is 0.1: 99.9 to 50. The magnetic recording medium according to claim 2, wherein the magnetic recording medium is 50. 4. The magnetic recording medium according to claim 2, wherein the titanate-based coupling agent is represented by Chemical formula 5. [Chemical 5] 5. The magnetic recording medium according to claim 1, wherein the protective film is a carbon film. 6. The magnetic recording medium according to claim 1, which is a tape-shaped medium.