JPH0528463A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide a magnetic recording medium exhibiting excellent traveling property, wear resistance and durability even when used under various conditions. CONSTITUTION:A magnetic layer is provided on a nonmagnetic substrate to constitute the thin film-type magnetic recording medium. In this case, a long- chain alkyl compd. having carboxyl and amino groups and shown by RCH (NH2)COOH is used as the lubricant on the magnetic layer surface. In the formula, R is 10 to 30C hydrocarbons.

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 particularly to a magnetic recording using a long chain alkyl compound having a carboxyl group and an amino group in the molecule as a lubricant. It is about the medium.

[0002]

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 technique such as vapor deposition and the magnetic layer is used as a magnetic layer, the surface of the magnetic layer is not smooth. Since it is extremely good, the substantial contact area with sliding members such as magnetic heads and guide rollers is large, and therefore the coefficient of friction is large, and the adhesion phenomenon (so-called sticking) is likely to occur and running and durability are improved. There are many problems such as chipping.

Therefore, use of various kinds of lubricants has been studied in order to improve these problems, and a higher fatty acid or its ester has been conventionally top-coated on the magnetic layer of the magnetic recording medium. Attempts have been made to reduce the coefficient of friction. By the way, the lubricant used for the magnetic recording medium is required to have extremely strict characteristics, and it is difficult to cope with the conventional lubricant.

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. (2) Since the spacing with the magnetic head becomes a problem,
Being able to apply a very thin coating and exhibiting sufficient lubrication characteristics even in that case. (3) It must withstand a long time or use for a long time, and the lubricating effect should continue. Etc. are required.

However, conventionally used higher fatty acids and esters thereof are frozen and solidified under low temperature conditions such as 0 ° C. or lower to impair the function as a lubricant, and have long-term durability. Tend to lack. Further, perfluoropolyethers are only dissolved in chlorofluorocarbon, which causes an environmental problem.

[0006]

As described above, in the field of magnetic recording media, practical properties such as running property and durability are unsatisfactory due to lack of ability of the lubricant used. .. Therefore, the problem to be solved by the present invention is
An object of the present invention is to provide a magnetic recording medium that has excellent lubricity under various conditions of use, has a long-lasting lubrication effect, and has excellent running properties, abrasion resistance, durability, and the like. It also provides for achieving CFC removal in the coating process.

[0007]

As a result of extensive studies aimed at achieving this object, the present invention has revealed that a long-chain alkyl compound having a carboxyl group and an amino group in the molecule,
The inventors have found that they are suitable for solving this problem, and have completed the present invention. That is, the metal thin film type magnetic recording medium of the present invention is a magnetic recording medium in which at least a magnetic layer is formed on a non-magnetic support,

[0008]

Embedded image (general formula) RCH (NH ₂ ) COOH where R represents a hydrocarbon having 10 to 30 carbon atoms. It has a long-chain alkyl compound having a carboxyl group and an amino group in the molecule represented by.

That is, the present invention has good durability even when used under severe conditions such as high temperature and high humidity or low temperature and low humidity by applying to the surface of a metal thin film type magnetic recording medium such as a vapor deposition tape. And the characteristics thereof are not deteriorated. Long chain alkyl compounds having a carboxyl group and an amino group in these molecules are described, for example, by C.I. Hell et al. (Ber. 24, 2388, 1891) or N.O. Brace et al. (J. Org. Chem. 32, 430, 1).
967) and can be easily synthesized. In other words, adding a catalytic amount of phosphorus trichloride to the corresponding long-chain carboxylic acid,
It can be obtained by adding bromine dropwise to brominate the carbon at the α-position and then heating it with an alcohol solution of ammonia in a sealed tube or by reacting with ammonia gas under ice cooling. Although the synthesis method is not specifically described, the former document was referred to for long-chain hydrocarbons, and the latter document was referred to for those having a fluorine chain.

The alkyl compound having a carboxyl group and an amino group in the molecule of the present invention can be synthesized irrespective of the number of carbon atoms, but if it is a long-chain alkyl compound of 10 or more and 30 or less, the molecular weight, It can be selected regardless of the branched structure, isomer structure, or alicyclic structure. Among these, hydrocarbons having a linear structure are preferable. Specifically, those structures are shown in Table 1.

The magnetic recording medium of the present invention comprises a long-chain alkyl compound having a carboxyl group and an amino group in the molecule as a lubricant. The magnetic recording medium to which the present invention is applied can be applied to a so-called metal thin film type magnetic recording medium in which a metal film is formed as a magnetic layer on the surface of a non-magnetic support by a method such as vapor deposition. Further, in this metal thin film type magnetic recording medium,
It can be applied to a magnetic recording medium having a structure in which an underlayer is interposed between a non-magnetic support and a magnetic layer.

In this case, the nonmagnetic support of the applicable metal thin film type magnetic recording medium and the metal magnetic thin film are not limited, and any conventionally known one can be used. For example, as the non-magnetic support, the same one as the above-mentioned 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 as the non-magnetic support, an oxide film such as an alumite treatment or a Ni-P film is formed on the surface of the substrate to harden the surface. You may do so.

The metal magnetic thin film is formed as a continuous film by a PVD method such as plating, sputtering or vacuum deposition, and is made of a metal such as Fe, Co or Ni, or Co-Ni.
Alloys, Co-Pt alloys, Fe-Co-Ni alloys,
Fe-Co based alloy, Fe-Ni based alloy, Fe-Ni-B
Alloys, Fe-Co-B alloys, Fe-Co-Ni-B
Examples include an in-plane magnetization recording metal magnetic film and a Co—Cr alloy thin film made of a system alloy.

Particularly, in the case of in-plane magnetization recording metal magnetic thin film,
Bi, Sb, Pb, Sn, Ga, on the non-magnetic support in advance
An underlayer of a low melting point non-magnetic material such as In, Ge, or Ti is formed in advance, and a metal magnetic material is vapor-deposited or sputtered from the vertical direction to diffuse these low melting point non-magnetic material in the metal magnetic thin film, and the orientation May be eliminated to ensure in-plane isotropy and to improve anti-magnetism.

In the case of a hard disk, a hard protective film such as a carbon film, a diamond-like or amorphous carbon film, a chromium oxide film, a zirconium oxide film, and a SiO ₂ film is formed on the surface of the metal magnetic thin film. You may do it. Examples of the method of retaining the long-chain alkyl compound having a carboxyl group and an amino group in the molecule in the magnetic recording medium include a method of top-coating a lubricant layer on the surface of the magnetic film or the surface of the protective film. In this case, the coating amount of the long-chain alkyl compound having a carboxyl group and an amino group in the molecule is still 0.
More preferably 5-20 mg / m ² , and 1-20 mg / m ^2.
It is more preferably m ² .

The above long-chain alkyl compound having a carboxyl group and an amino group in the molecule 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, the extreme pressure agent may be used in a mixing ratio of about 30:70 to 70:30 by weight.

In the boundary lubrication region, the extreme pressure agent reacts with a metal surface due to frictional heat accompanying partial metal contact, thereby forming a reaction product to cause friction,
As the anti-wear agent, any of a phosphorus-based extreme pressure agent, a sulfur-based extreme pressure agent, a halogen-based extreme pressure agent, an organometallic extreme pressure agent, a composite extreme pressure agent and the like can be used. In addition to the above-mentioned lubricant and extreme pressure agent, a rust preventive agent may be used in combination if necessary.

As the rust preventive, any rust preventive commonly used as a rust preventive for magnetic recording media of this type can be used. For example, phenols, naphthols, quinones,
A heterocyclic compound containing a nitrogen atom, a heterocyclic compound containing an oxygen atom, a heterocyclic compound containing a sulfur atom, and the like. The rust preventive agent may be used in combination with a lubricant containing a long-chain alkyl compound having a carboxyl group and an amino group in the molecule, but a magnetic layer is formed on a non-magnetic support and the rust preventive agent is formed thereon. After applying the rust agent layer, apply the lubricant layer.
The effect is high when it is applied in layers or more.

By the way, in any of the above-mentioned magnetic recording media, a back coat layer, a base layer, etc. may be formed, if necessary, in addition to the magnetic coating film and the metallic coating film which are the magnetic layers. For example, the back coat layer is formed by coating a resin binder similar to that of the magnetic coating film with carbon fine powder for imparting conductivity and an inorganic pigment for controlling the surface roughness. In the present invention, the long-chain alkyl compound having a carboxyl group and an amino group in the molecule may be internally added as a lubricant to the back coat layer or may be contained by a top coat. Alternatively, all of the magnetic coating film, the metallic magnetic coating film and the back coat layer may be internally combined as a long-chain alkyl compound having a carboxyl group and an amino group in the molecule and top-coated, and various combinations are possible.

[0020]

[Function] A long-chain alkyl compound having a carboxyl group and an amino group in the molecule exerts a good lubricating effect to reduce the friction coefficient. Further, this lubricating action is not impaired even under severe conditions such as low temperature. Therefore, a magnetic recording medium using a long-chain alkyl compound having a carboxyl group and an amino group in its molecule as a lubricant has a running property due to the above-mentioned lubrication effect of the long-chain alkyl compound having a carboxyl group and an amino group in the molecule. Is improved and durability is improved.

[0021]

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. Table 1 shows long-chain alkyl compounds having a carboxyl group and an amino group in the molecule synthesized according to the above-mentioned synthesis example.

Using the compounds shown in Table 1, magnetic recording media shown below were prepared. An example applied to a metal thin film type magnetic recording medium (vapor deposition tape) will be described. -Example 1-Co was deposited on a polyethylene terephthalate film having a thickness of 14 μm by the oblique evaporation method to form a ferromagnetic metal thin film having a thickness of 200 nm. Next, on the surface of this magnetic thin film, the compound 1 in Table 1 was applied by a vacuum vapor deposition method so that the coating amount was 5 mg / m ^2, and cut into 8 mm width to prepare a sample tape.

-Examples 2 to 6-Samples were prepared in the same manner as in Example 1 except that Compound 1 in Table 1 used as a lubricant in Example 1 was replaced with Compound 2 to Compound 7. A tape was made. For each sample tape prepared as described above, measure the friction coefficient, still durability, and shuttle durability at a temperature of 25 ° C and a humidity of 60%, a temperature of -5 ° C, and a temperature of 40 ° C and a humidity of 80%. went. For still durability, the decay time of the output in the pause state up to -3 dB was evaluated. Shuttle durability is 2 per time
The shuttle was run for 1 minute and evaluated by the number of shuttles until the output decreased by 3 dB.

As a comparative example, a case was also evaluated in which a plank tape containing no lubricant, a carboxylic acid and an amine compound were used alone. The results are shown in Table 2. As is clear from Table 2, when used as a long-chain alkyl compound having a carboxyl group and an amino group in the molecule, as compared with the case where a carboxylic acid and an amine were used alone as a lubricant, the friction coefficient and the still durability were improved. As for the shuttle durability, very good results were obtained without deterioration under various conditions.

[0025]

As is clear from the above description, the magnetic recording medium of the present invention has a long-chain alkyl compound having a carboxyl group and an amino group in the molecule having a very excellent lubricity as a lubricant. Therefore, the lubricity can be maintained under any use condition, and the lubricity can be maintained for a long period of time. Therefore, the magnetic recording medium of the present invention is excellent in running property, wear resistance and durability. In addition, since vacuum deposition can be used as a method of depositing the lubricant, it is not necessary to use an organic solvent such as CFC, and therefore there is no problem from an environmental point of view.

[0026]

[Table 1] Synthesized lubricant

[0027]

[Table 2] Durability measurement results

Claims (1)

What is claimed is: 1. A magnetic recording medium comprising at least a magnetic layer on a non-magnetic support, wherein the surface of the magnetic layer has a carboxyl group and an amino group in the molecule represented by the following general formula. A magnetic recording medium comprising a long-chain alkyl compound having Embedded image (general formula) RCH (NH ₂ ) COOH where R represents a hydrocarbon having 10 or more and 30 or less carbon atoms.