JP3211987B2 - 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 such as a magnetic tape and a magnetic disk, and more particularly to a magnetic recording medium having a lubricant on the surface of a magnetic layer.

[0002]

SUMMARY OF THE INVENTION The present invention relates to a magnetic recording medium having a magnetic layer comprising a metal magnetic thin film on a non-magnetic support, wherein the magnetic layer comprises an amino acid ester having a long-chain hydrocarbon group in the molecule or an amino acid ester in the molecule. An object of the present invention is to provide a magnetic recording medium exhibiting excellent running properties, abrasion resistance, and durability under various use conditions by holding an amide having a long-chain hydrocarbon group and a hydroxyl group as a lubricant.

[0003]

2. Description of the Related Art For example, in a so-called metal thin film type magnetic recording medium in which a ferromagnetic metal material is deposited on a non-magnetic support by a method such as vapor deposition and the magnetic layer is used as a magnetic layer, the surface of the magnetic layer has a smoothness. Because it is extremely good, a substantial contact area with a sliding member such as a magnetic head or a guide roller is large,
Therefore, there are many problems such as a large friction coefficient, a tendency for adhesion (so-called sticking) to occur, and lack of running property and durability.

[0004] In order to solve these problems, the use of various lubricants has been studied. Conventionally, higher fatty acids and esters thereof have been applied to the magnetic layer of the magnetic recording medium by top coating. Attempts have been made to reduce the coefficient of friction.

Incidentally, lubricants used for magnetic recording media are required to have extremely strict characteristics due to their properties, and it is presently difficult for conventional lubricants to cope with them.

[0006] Lubricants used for magnetic recording media include (1) excellent low-temperature characteristics so as to ensure a predetermined lubricating effect when used in a cold region, and (2) lubricant with a magnetic head. Since pacing poses a problem, it must be able to be applied very thinly, exhibit sufficient lubrication properties even in that case, and (3) endure long-term use or long-term use and maintain the lubricating effect. Required.

However, conventionally used higher fatty acids and esters thereof are frozen and solidified under low-temperature conditions such as 0 ° C. or lower, so that the function as a lubricant is impaired or the long-term durability is reduced. Tend to lack.

[0008]

As described above, in the field of magnetic recording media, due to lack of ability of the lubricant used, the practical characteristics such as running property and durability remain unsatisfactory. I have. Therefore, the present invention provides a magnetic recording medium that maintains excellent lubricity under various use conditions, maintains a lubricating effect for a long time, and has excellent running properties, wear resistance, durability, and the like. It is the purpose.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the achievement of the above-mentioned object, and as a result, have found that a magnetic recording medium having the following amino acid ester or amide is suitable for this purpose. And completed the present invention.

That is, according to the present invention, a magnetic layer comprising a metal magnetic thin film provided on a nonmagnetic support has an amino acid ester represented by the following general formula I or an amide represented by the following general formula II. The present invention relates to a magnetic recording medium that is used. General formula I: (However, in this general formula, R ¹ is a long-chain hydrocarbon group having 10 or more carbon atoms, and R ² is a hydrogen atom or an alkyl group which may have a substituent.) General formula II: R ³ —CONH—R ⁴ —OH (wherein, in this general formula, R ³ is a hydrocarbon group having 6 or more carbon atoms, and R ⁴ is an alkylene group which may be substituted with a hydroxyl group.)

[0011]

[0012]

[0013]

[0014]

The present invention is effective because the magnetic layer in the above magnetic recording medium is of a metal thin film type.

That is, the present invention is particularly applicable to severe conditions such as high-temperature high-humidity or low-temperature low-humidity by applying a lubricant of the above general formula I or II on the surface of a thin film magnetic recording medium such as a vapor-deposited tape. Good durability can be obtained even when used below, and the characteristics do not deteriorate.

In the amino acid ester of the above-mentioned general formula I used in the present invention, the long-chain alkyl group (R ¹ ) is selected irrespective of the molecular weight, branched structure, unsaturated bond, isomer structure and alicyclic structure. Can be. When the carbon number is 10 or more, the durability of the medium is improved. However, for solubility, the carbon number of R ¹ is preferably 30 or less.

Further, as for R ² , when R ² is an alkyl group, there is no particular limitation on the number of carbon atoms. This R ²
May have a substituent such as a hydroxyl group, a halogen or a cyano group. The number of such substituents is not particularly limited, but is preferably 2 or less.

The structure of the amino acid ester of the general formula I used in the present invention is specifically shown in Table 1 below.

Next, in the amide of the general formula II used in the present invention, R ³ can be selected irrespective of the molecular weight, branched structure, unsaturated bond, isomer structure and alicyclic structure. If the carbon number is not 6 or more, the durability of the medium will be poor. However, considering the solubility, the carbon number of R ³ is preferably 30 or less.

There is no particular limitation on the length of R ⁴ , but the number of carbon atoms is preferably 3 or more. The number of hydroxyl groups is not particularly limited, but should be 1 or more, and preferably 5 or less. When this number increases, the solubility becomes poor and it becomes impractical.

The specific structure of the amide of the general formula II used in the present invention is shown in Table 2 below.

Here, as a magnetic recording medium to which the present invention is applied, for example, as shown in FIG. 1, a magnetic film is formed as a magnetic layer 2 on the surface of a nonmagnetic support 1 by a method such as vapor deposition. It can be applied to a so-called metal thin film type magnetic recording medium. In this metal thin film type magnetic recording medium, the above-mentioned lubricant layer 3 is provided on the magnetic layer 2.
Underlayer (not shown) between nonmagnetic support 1 and magnetic layer 2
Can be applied to a magnetic recording medium having a configuration via

In this case, the non-magnetic support of the metal thin film type magnetic recording medium and the metal magnetic thin film to which the present invention can be applied are not particularly limited, and any conventionally known ones can be used.

For example, as the nonmagnetic support,
The same type as the coating type magnetic recording medium can be used.
In this case, when a rigid substrate such as an Al alloy plate or a glass plate is used for 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. You may make it.

The metal magnetic thin film is formed as a continuous film by a PVD technique such as plating, sputtering, or vacuum deposition, and is made of a metal such as Fe, Co, or Ni, a Co—Ni alloy, or a Co—Ni alloy.
-Pt alloy, Co-Pt-Ni alloy, Fe-Co alloy, Fe-Ni
Alloy, Fe-Co-Ni alloy, Fe-Ni-B alloy, Fe-Co
In-plane magnetization recording metal magnetic films and Co-Cr-based alloy thin films made of -B-based alloys, Fe-Co-Ni-B-based alloys and the like are exemplified. A hard protective film such as a carbon film, a diamond-like or amorphous carbon film, a chromium oxide film, and a SiO ₂ film may be formed on the surface of the metal magnetic thin film.

In particular, in the case of an in-plane magnetization recording metal magnetic thin film,
Bi, Sb, Pb, Sn, Ga, In, Ge, S on a non-magnetic support in advance
forming an underlayer of a low-melting nonmagnetic material such as i, Tl,
Metallic magnetic material is deposited or sputtered from the vertical direction,
By diffusing these low-melting non-magnetic materials into the metal magnetic thin film, eliminating orientation and ensuring in-plane isotropy,
The coercivity may be improved.

In addition, as a method for retaining an amino acid ester of the above general formula I having a long-chain hydrocarbon group in the molecule or an amide of the above general formula II having an amide group and a hydroxyl group in the molecule, A method of top-coating a lubricant layer on the surface of the magnetic thin film or the surface of the protective film may be used. In this case, the amount of the amino acid ester or amide to be applied is preferably 0.5 to 100 mg / m ² , and 1 to 20 mg / m ^2.
More preferably, it is mg / m ² . These amino acid esters and amides may be used together in the same layer.

The amino acid ester or amide may be used alone as a lubricant for a magnetic recording medium, or may be used in combination with a conventionally known lubricant.

Further, in order to cope with more severe conditions and maintain the lubricating effect, an extreme pressure agent may be used in combination at a weight ratio of about 30:70 to 70:30.

The extreme pressure agent reacts with the metal surface due to frictional heat generated when the metal contact occurs partially in the boundary lubrication region, and forms a reaction product film to thereby prevent friction and wear. A phosphorus-based extreme pressure agent,
Sulfur-based extreme pressure agent, halogen-based extreme pressure agent, organometallic extreme pressure agent,
Any of composite extreme pressure agents and the like can be used.

Further, in addition to the above-mentioned lubricant and extreme pressure agent, if necessary, a rust preventive may be used in combination. As the rust inhibitor, any one which is usually used as a rust inhibitor for this type of magnetic recording medium can be used, for example, phenols, naphthols, quinones, heterocyclic compounds containing a nitrogen atom, oxygen atoms And heterocyclic compounds containing a sulfur atom.

Incidentally, in the above-described metal thin film type magnetic recording medium, a back coat layer, an undercoat layer and the like may be formed as necessary in addition to the metal magnetic thin film as the magnetic layer.

For example, the back coat layer is formed by adding a carbon-based fine powder for imparting conductivity or an inorganic pigment for controlling the surface roughness to the same resin binder as that of the magnetic coating film. Things.

In the present invention, the amino acid ester and / or amide may be added to the back coat layer as a lubricant internally or by a top coat. Alternatively, various combinations such as internal addition and top coating of the above-mentioned amino acid ester or amide lubricant to any of the magnetic coating film, the metal magnetic thin film and the back coat layer are also possible. The present invention can be applied to not only a metal thin film type but also a coating type magnetic recording medium and a magnetic recording medium using an oxide magnetic powder.

[0036]

The magnetic layer made of a metal magnetic thin film has good properties because it has an amino acid ester having a long-chain hydrocarbon group in the molecule or an amide having an amide group and a hydroxyl group in the molecule as a lubricant. It not only reduces the coefficient of friction by exerting a lubricating effect, but also improves the durability of stills and shuttles. Further, this lubricating action is not impaired even under severe conditions such as low temperature. Therefore, in the magnetic recording medium using the above-mentioned amino acid ester or amide as a lubricant, the running property is improved and the durability is improved by the lubricating effect.

[0037]

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.

Using the lubricants shown in Tables 1 and 2, the following magnetic recording media were prepared. An embodiment applied to a metal thin film type magnetic recording medium (evaporated tape) will be described.

Example 1 Co was applied to a 14 μm thick polyethylene terephthalate film by oblique evaporation to form a 200 nm thick ferromagnetic metal thin film. Next, a carbon film was formed on the surface of the metal magnetic thin film by sputtering to a thickness of 20 nm, and the lubricant shown in Table 1 dissolved in a mixed solvent of Freon and ethanol was applied so that the application amount was 5 mg / m ^2. , 8 mm wide to prepare a sample tape.

Sample tapes were prepared in the same manner as in Example 1 except that the lubricants in Examples 2 to 11 and Comparative Examples 1 to 3 were changed as shown in Table 1.

Examples 12 to 22 Sample tapes were prepared in the same manner as in Example 1, except that the lubricant was changed as shown in Table 2.

Each of the sample tapes prepared as described above was subjected to a temperature of -5 ° C. at a temperature of 25 ° C. and a humidity of 60%.
At this time, the friction coefficient, still durability, and shuttle durability under the conditions of a temperature of 40 ° C. and a humidity of 80% were measured. The still durability evaluated the decay time of the output in the pause state to -3 dB. Shuttle durability was evaluated by the number of shuttles required for the shuttle to run for 2 minutes each time and the output to decrease by 3 dB.

As a comparative example, a blank tape having no lubricant (Comparative Example 1) and various perfluoropolyethers having carboxyl groups or hydroxyl groups at ends (Comparative Examples 2 and 3) were lubricated alone. It was also measured when used as an agent. Tables 3 and 4 also show the durability measurement results.

As is apparent from the results of Tables 3 and 4, based on the present invention, an amino acid ester having a long-chain hydrocarbon in the molecule and an amide having an amide group and a hydroxyl group in the molecule are used as the lubricant. As a result, the durability such as the coefficient of friction, still durability and shuttle durability was not deteriorated even under various conditions, and very good results were obtained.

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

As is clear from the above description, the magnetic recording medium of the present invention has an amino acid ester having a long-chain hydrocarbon group in the molecule or an amide in the molecule having extremely excellent lubricity. Since the amide having a hydroxyl group and a hydroxyl group is held as a lubricant, lubricity can be maintained under any use conditions, and the lubricity can be maintained for a long period of time. Therefore, the magnetic recording medium of the present invention has excellent running properties, wear resistance and durability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a magnetic recording medium of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Non-magnetic support 2 ... Metal magnetic thin film 3 ... Lubricant layer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tatsuya Yamada 1-3-3 Chiwakacho, Kanagawa-ku, Yokohama, Kanagawa Prefecture Within Nisshin Fine Chemical Co., Ltd. (72) Inventor Yuzo Higaki 1, Chiwakacho, Kanagawa-ku, Yokohama, Kanagawa No. 3, Nisshin Fine Chemical Co., Ltd. (56) References JP-A-2-24831 (JP, A) JP-A-4-187662 (JP, A) JP-A-58-1797 (JP, A) JP-A Sho JP-A-4-32020 (JP, A) JP-A-63-39125 (JP, A) JP-A-59-157844 (JP, A) JP-A-61-114726 (JP, A) A) US Patent 4,331,545 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C10M 101/00-177/00 C10N 10:00-80:00

Claims (1)

(57) [Claims] 1. A magnetic layer comprising a metal magnetic thin film provided on a non-magnetic support, which contains an amino acid ester represented by the following general formula I or an amide represented by the general formula II as a lubricant. Magnetic recording media. General formula I: (However, in this general formula, R ¹ is a long-chain hydrocarbon group having 10 or more carbon atoms, and R ² is a hydrogen atom or an alkyl group which may have a substituent.) General formula II: R ³ —CONH—R ⁴ —OH (wherein, in this general formula, R ³ is a hydrocarbon group having 6 or more carbon atoms, and R ⁴ is an alkylene group which may be substituted with a hydroxyl group.)