JPH0620262A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To sustain lubricity for a long time under various use conditions by coating the surface of magnetic layer with perfluoropolyether and then coating with long chain hydrocarbon compound. CONSTITUTION:Surface of magnetic layer is coated with perfluoropolyether having carboxyl group in molecule and then coated with long chain hydrocarbon having amino group. When a thin film magnetic recording medium is subjected to coating, high durability is achieved even under severe conditions of high temperature high humidity or low humidity without sacrifice of its characteristics. Carbon number of the long chain hydrocarbon having amino group in the molecule is set in the range of 6-30 and the hydrocarbon can be selected irrespective of branch structure, unsaturated linkage, isomer structure, or alicyclic structure. Appropriate dissolvability is achieved by setting the number of amino groups in molecule at three or below. Travelability is improved by the lubricity of lubricant layer coated with long chain hydrocarbon.

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, coated with perfluoropolyether having a carboxyl group, a hydroxyl group, an alkoxycarbonyl group or a piperonyl group in its molecule. The present invention relates to a magnetic recording medium later coated with a long chain hydrocarbon having an amino group.

[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 method such as vapor deposition and used as a magnetic layer, the smoothness of the magnetic layer surface is Since it is extremely good, the substantial contact area with sliding members such as magnetic heads and guide rollers is large,
Therefore, there are many problems such that the friction coefficient becomes large and the adhesion phenomenon (so-called sticking) is likely to occur and running performance and durability are lacking.

Therefore, use of various kinds of lubricants has been studied in order to improve these problems, and friction has been hitherto caused by top-coating a higher fatty acid or ester thereof on the magnetic layer of the magnetic recording medium. Attempts have been made to reduce the coefficient. By the way, the lubricant used in 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 for 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) a lubricant with a magnetic head. Since pacing is a problem, it is necessary to be able to apply it extremely thinly, to exhibit sufficient lubrication characteristics even in that case, and (3) to endure long-term use or long-term use and to maintain the lubrication effect. To be done.

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

[0006]

As described above, in the field of magnetic recording media, practical characteristics such as running durability are left unsatisfactory due to lack of ability of the lubricant used. Therefore, the present invention provides a magnetic recording medium that maintains excellent lubricity under various conditions of use, has a long-lasting lubrication effect, and is excellent in runnability, wear resistance, durability, and the like. It is intended.

[0007]

Means for Solving the Problems The present inventor has conducted extensive studies as a means of achieving the above object, and as a result, perfluoropolyether having a carboxyl group, a hydroxyl group, an alkoxycarbonyl group or a piperonyl group in the molecule. The present invention has been completed by finding that a magnetic recording medium in which a long-chain hydrocarbon having an amino group in the molecule is applied after applying is suitable for this purpose.

That is, the magnetic recording medium of the present invention is a magnetic recording medium having at least a magnetic layer formed on a non-magnetic support, and has a carboxyl group, a hydroxyl group, an alkoxycarbonyl group or a piperonyl group in the molecule. This is a magnetic recording medium in which a long-chain hydrocarbon having an amino group in the molecule is applied after applying the perfluoropolyether.

That is, the present invention provides good durability even when used under harsh conditions such as high temperature and high humidity or low temperature and low humidity by being applied to the surface of a thin film magnetic recording medium such as a vapor deposition tape. Moreover, the characteristics are not deteriorated.

The long-chain hydrocarbon having an amino group in the molecule of the present invention specifically has the structure shown in Table 1, but has a carbon number of 6 or more and 30 or less, a branched structure, an unsaturated bond, It can be selected regardless of the isomer structure or the alicyclic structure. More preferably, the number of carbon atoms is 10 or more, and 22 or less is linear. When the carbon number is small, the effect is small, and when the carbon number is large, the solubility is small, so that it becomes uncommon.

The number of amino groups in the molecule is not particularly limited, but if it is too large, solubility will be a problem, so it is preferably 3 or less. It is possible to use a commercially available perfluoropolyether as the skeleton of the perfluoropolyether having a polar group at the terminal, for example, as an example,

Fomblin made by Montecatini

[Chemical 1]

Demnum manufactured by Daikin Industries, Ltd.

[Chemical 2]

Craytox made by DuPont

[Chemical 3] However, it is not limited to this.

Here, p, q, and n in the chemical structural formula of the perfluoropolyether are integers of 1 or more. The molecular weight is not particularly limited, but is preferably about 600 to 5,000. If the molecular weight is too large, the effect of the adsorbing group will be small, and if it is small, the effect of fluorine will be weakened.

The magnetic recording medium of the present invention is coated with a perfluoropolyether having a polar group such as a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, or a piperonyl group in the molecule, and then has a polar group, particularly an amino group, in the molecule. It has a lubricant layer coated with long-chain hydrocarbons.

The magnetic recording medium to which the present invention is applied is a so-called metal thin film type magnetic recording medium in which a magnetic film is formed as a magnetic layer on the surface of a non-magnetic support by a method such as vapor deposition. It is possible. Further, this metal thin film type magnetic recording medium 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 non-magnetic support and the metal magnetic thin film of the applicable metal thin film type magnetic recording medium are not particularly 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 it.

The metallic 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, Co-Pt-Ni alloys,
Fe-Co based alloy, Fe-Ni based alloy, Fe-Co-N
Examples are in-plane magnetization recording metal magnetic films and Co-Cr alloy thin films made of i-based alloys, Fe-Ni-B-based alloys, Fe-Co-B-based alloys, Fe-Co-Ni-B-based alloys, and the like. .

Particularly in the case of an 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, Si, or Ti is formed, and a metal magnetic material is vapor-deposited or sputtered from the vertical direction to diffuse the low-melting point non-magnetic material in the metal magnetic thin film. The orientation may be eliminated to secure the in-plane isotropic property, and the coercive force may be improved.

In the case of the hard disk as described above, 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 is formed on the surface of the metal magnetic thin film. Good.

The metal thin film type magnetic recording medium is coated with perfluoropolyether having a polar group such as a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, or a piperonyl group in the molecule, and then has an amino group in the molecule. As a method of retaining the lubricant layer coated with the long-chain hydrocarbon, there is a method of top-coating the lubricant layer on the surface of the metal magnetic thin film or the surface of the protective film. In this case, apply perfluoropolyether having a polar group such as carboxyl group, hydroxyl group, alkoxycarbonyl group, or piperonyl group in the molecule and then apply long-chain hydrocarbon having amino group in the molecule to apply lubricant. The quantity is 0.
5-100 mg / m ² is desirable, 1-20
More preferably, it is mg / m ² .

In the above-mentioned molecule, a carboxyl group, a hydroxyl group,
A lubricant layer coated with perfluoropolyether having a polar group such as an alkoxycarbonyl group or a piperonyl group and then a long-chain hydrocarbon having an amino group in the molecule is used alone as a lubricant for magnetic recording media. However, it may be used in combination with a conventionally known lubricant. Further, an extreme pressure agent may be used in combination at a weight ratio of about 30:70 to 70:30 in order to cope with more severe conditions and maintain the lubricating effect.

The extreme pressure agent reacts with the metal surface by frictional heat generated when a metal contact is partially generated in the boundary lubrication region, and forms a reaction product film to prevent friction and wear. Which is a phosphorus-based extreme pressure agent,
Sulfur-based extreme pressure agent, halogen-based extreme pressure agent, organometallic extreme pressure agent,
Any compound type extreme pressure agent or 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, and examples thereof include phenols, naphthols, quinones, nitrogen atom-containing heterocyclic compounds, and oxygen atoms. And a heterocyclic compound containing a sulfur atom.

By the way, in the above-mentioned metal thin film type magnetic recording medium, a back coat layer, an undercoat layer and the like may be formed, if necessary, in addition to the metal magnetic thin film which is the magnetic layer. For example, the back coat layer is formed by applying a carbon-based fine powder for imparting conductivity to a resin binder similar to that of the magnetic coating film or an inorganic pigment for controlling the surface roughness.

In the present invention, the back coat layer is coated with a perfluoropolyether having a polar group such as a carboxyl group, a hydroxyl group, an alkoxycarbonyl group or a piperonyl group in the above-mentioned molecule, and then an amino group is introduced into the molecule. A lubricant coated with the long-chain hydrocarbon may be internally added or may be contained by a top coat. Alternatively,
Magnetic coating, metal magnetic thin film and back coat layer all have amino groups in the molecule after applying perfluoropolyether having polar groups such as carboxyl group, hydroxyl group, alkoxycarbonyl group or piperonyl group in the molecule Various combinations such as internal addition and top coating as a lubricant coated with long-chain hydrocarbon are also possible.

[0028]

[Function] A lubricant prepared by coating a perfluoropolyether having a polar group such as a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, or a piperonyl group in the molecule and then coating a long-chain hydrocarbon having an amino group in the molecule is It 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, after applying perfluoropolyether having a polar group such as a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, or a piperonyl group in the molecule, a lubricant layer coated with a long chain hydrocarbon having an amino group in the molecule is formed. The magnetic recording medium has a carboxyl group in the molecule,
A perfluoropolyether having a polar group such as a hydroxyl group, an alkoxycarbonyl group, or a piperonyl group is coated, and then a long-chain hydrocarbon having a polar group in the molecule is coated. The durability is improved.

[0029]

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. The composition of the lubricant layer is shown by coating perfluoropolyether having a polar group such as carboxyl group, hydroxyl group, alkoxycarbonyl group, or piperonyl group in the molecule and then coating a long chain hydrocarbon having an amino group in the molecule. Shown in 1. The magnetic recording media shown below were prepared using the compounds shown in Table 1. 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 10 μm by an oblique evaporation method to form a ferromagnetic metal thin film having a thickness of 200 nm. Next, the lubricant 1 in Table 1 dissolved in a mixed solvent of freon and ethanol was coated on the surface of the metal magnetic thin film so that the coating amount was 5 mg / m ^2, and cut into 8 mm width. A sample tape was prepared.

-Examples 2 to 14-The same as Example 1 except that the lubricant 1 in Table 1 used as the lubricant composition in Example 1 was replaced with lubricants 2 to 14. A sample tape was prepared according to the method.

Each of the sample tapes manufactured as described above has a temperature of −5 when the temperature is 25 ° C. and the humidity is 60%.
When the temperature was 40 ° C., the temperature was 40 ° C. and the humidity was 80%, the friction coefficient, the still durability, and the shuttle durability were measured. Still durability is -3dB of output in pause state
The decay time up to was evaluated. The shuttle durability was evaluated by performing shuttle travel for 2 minutes each time and counting the number of shuttles until the output decreased by 3 dB. In addition, as a comparative example, a blank tape containing no lubricant and a case where perfluoropolyether having a polar group at the end was used alone as a lubricant were also measured. A comparative example is shown in Table 2 and measurement results are shown in Tables 3 to 7.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

[0037]

[Table 5]

[0038]

[Table 6]

[0039]

[Table 7]

As is clear from Tables 3 to 7, the carboxyl group in the molecule is more than that in the case where perfluoropolyether having a carboxyl group, a hydroxyl group, an alkoxycarbonyl group or a piperonyl group in the molecule is used alone as a lubricant. Friction coefficient by using perfluoropolyether having polar group such as hydroxyl group, hydroxyl group, alkoxycarbonyl group, or piperonyl group and then applying long chain hydrocarbon having amino group in the molecule The still durability, shuttle durability, etc. were very good without deterioration under various conditions.

[0041]

As is apparent from the above description, the magnetic recording medium of the present invention has a carboxyl group, a hydroxyl group,
Since a perfluoropolyether having a polar group such as an alkoxycarbonyl group or a piperonyl group is coated and then a long-chain hydrocarbon having an amino group in the molecule is coated, it has a lubricant layer, so it can be used under any conditions of use. The lubricity can be maintained, 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.

Claims (7)

[Claims] 1. In a magnetic recording medium having at least a magnetic layer on a non-magnetic support, after coating the surface of the magnetic layer with perfluoropolyether,
A magnetic recording medium, characterized in that a long-chain hydrocarbon compound is applied. 2. The magnetic recording medium according to claim 1, wherein the long chain hydrocarbon compound has a polar group. 3. The magnetic recording medium according to claim 2, wherein the polar group is an amino group. 4. The magnetic recording medium according to claim 2, wherein the perfluoropolyether has a carboxyl group in the molecule. 5. The magnetic recording medium according to claim 2, wherein the perfluoropolyether has a hydroxyl group in the molecule. 6. The magnetic recording medium according to claim 2, wherein the perfluoropolyether has a piperonyl group in the molecule. 7. The magnetic recording medium according to claim 2, wherein the perfluoropolyether has an alkoxycarbonyl group in the molecule.