JPH09120529A - Magnetic recording medium and production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium having high quality by suppressing the decrease in the initial coefft. of friction of a magnetic tape and the increase in the coefft. of friction by repetitive traveling and preservation under a high-temp. and high-humidity environment. SOLUTION: A striped oriented layer 4 consisting of org. matter is disposed on a protective film 3, by which the orienting and adhesive powder of a lubricant is improved. This recording medium has the constitution obtd. by successively laminating a magnetic recording layer consisting of a ferromagnetic metallic thin film 2, a protective film 3 consisting of carbon, the oriented layer 4 for orienting and adhering the lubricant and a lubricant layer 5 on a nonmagnetic substrate 1. The oriented layer has the striped shapes formed by rubbing a thin film layer mainly composed of the org. matter disposed on a thin-film carbon layer with a non-woven fabric, film, etc. The oriented layer 4 is also obtainable by rubbing the non-woven fabric, film, etc., mainly composed of the org. matter to the thin-film carbon layer thereby sticking the org. matter in a stripe form thereto.

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 having a magnetic recording layer made of a magnetic metal thin film and a method for manufacturing the same, and more particularly to a method for firmly attaching and orienting a lubricant on a carbon protective film. .

[0002]

2. Description of the Related Art In the field of magnetic recording, high performance such as digitalization, miniaturization, and long time has been advanced in recent years. A ferromagnetic metal thin film type magnetic recording medium, which is formed by forming a ferromagnetic metal thin film on a support by electron beam vapor deposition, sputtering or the like, a so-called vapor-deposited tape is extremely advantageous for short wavelength recording, and thus has been actively studied. Some have begun to be put to practical use as magnetic tapes for audio or video.

A conventional ferromagnetic metal thin film type magnetic recording medium will be described below. FIG. 5 is an enlarged sectional view of a conventional magnetic recording medium. In FIG. 5, reference numeral 1 is a polymer film such as a polyester film or a polyimide film, or a non-magnetic substrate such as an aluminum thin film. Reference numeral 2 is a ferromagnetic metal thin film that constitutes the magnetic recording layer, and is formed on the substrate 1 by a vacuum deposition method such as electron beam deposition method, sputtering method or ion plating method using cobalt, nickel, iron or an alloy containing them as a main component. Is formed in. 3 is a protective film made of a thin carbon layer and is a plasma CV
The lubricant layer 5 is formed by the D or sputtering method, and the organic compound is formed on the thin film carbon layer by a conventional coating method or a vacuum deposition method.

In the magnetic recording medium having the above-mentioned structure, for example, in the case of a magnetic tape, the surface of the magnetic layer has a very good surface property in order to achieve high density magnetic recording. Therefore, the running durability is greatly affected by friction and wear under high speed sliding with the magnetic head during the recording / reproducing process of the magnetic signal, and its improvement is a major issue.

Therefore, protective films and lubricants having excellent running durability and corrosion resistance have been developed. For example, Si-N-O disclosed in JP-A-61-131231
In which a lubricant layer is formed on a system thin film, JP-A-61-12
Japanese Patent No. 6627 and Japanese Patent Application Laid-Open No. 62-219314 propose a hard carbon layer on which a fluorine-based lubricant is disposed. In addition, JP-A-6-19569
Japanese Patent No. 6 discloses an effort to further increase the performance of the protective film by further forming the protective layer into multiple layers and sharing the functions among the respective layers.

[0006]

However, in the conventional magnetic recording medium, since the carbon protective film having excellent durability and storability has a weak affinity with the lubricant, the lubricant is simply dispersed on the carbon protective film. It is in the state that it is only listed in. That is, since the lubricant is not oriented, its performance cannot be fully exhibited and friction cannot be reduced. In addition, repeated running and storage at high temperature lost the lubricant on the protective film, further increased friction, made unstable running, and caused damage such as one-sided stretching of the tape.

Here, the adhesion with the lubricant can be improved by changing the conditions for forming the carbon protective film. In this case, however, the protective film may be scraped off at the time of still regeneration, or under high temperature and high humidity environment. There was a problem that rust occurred on the magnetic metal thin film when stored in.

Therefore, in view of the above conventional circumstances, the present invention provides a high-quality magnetic recording having a stable carbon protective film with a lubricant strongly oriented and adhered, which is excellent in running stability, high durability, and weather storability. The purpose is to provide a medium.

[0009]

To achieve this object, the present invention provides a magnetic recording layer comprising a magnetic metal thin film on a non-magnetic support, a protective film layer such as carbon, and an alignment for depositing a lubricant. It has a structure in which a layer and a lubricant layer are sequentially laminated.

The orientation layer can be obtained by rubbing a thin film layer mainly composed of an organic material provided on the thin film carbon layer with a non-woven fabric, a film or the like. It can also be obtained by rubbing a thin film carbon layer with a non-woven fabric, a film or the like mainly composed of an organic substance.

As a result, microscopic streak-shaped grooves made of an organic substance as an alignment layer are provided on the surface of the carbon protective film, and the lubricant having an elongated molecular structure is oriented in the direction of the grooves. Further, the organic material layer has a stronger affinity with the lubricant than the carbon protective film, and adheres the lubricant more firmly.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is characterized in that a magnetic metal thin film, a protective film layer, an alignment layer, and a lubricant layer are sequentially laminated on a non-magnetic support, and is magnetic recording. This is a medium, in which an alignment layer is provided on the surface of the carbon protective film, and the lubricant having a long and narrow molecular structure is aligned in the same direction. Further, the organic material layer has a stronger affinity with the lubricant than the carbon protective film, and adheres the lubricant more firmly.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the structure of a magnetic tape used in the embodiment of the present invention. In FIG. 1, 1 is a non-magnetic substrate made of a polymer film, 2 is a ferromagnetic metal thin film, 3 is a protective film, 4 is an alignment layer, 5 is a lubricant layer, and 6 is a back coat layer.

Polyethylene terephthalate is often used as the non-magnetic substrate, but other polyester films such as polyethylene naphthalate, cellulose derivatives such as cellulose acetate, plastic films such as polyamide and polyimide, and aluminum thin films are used. it can.

As the ferromagnetic metal thin film, iron, cobalt, nickel or an alloy containing them as a main component formed by a vacuum deposition method, a sputtering method or an ion plating method, or a partial oxide or a partial nitride thereof is used. Can be used.

The protective film mainly composed of carbon uses a hydrocarbon gas, a hydrocarbon gas containing nitrogen, fluorine or other elements or a mixed gas of these gases and an inert gas such as helium, neon or argon. Plasma C
It is formed by the VD method or carbon sputtering.

As shown in FIG. 2, the alignment layer is provided with microscopic streak-like grooves by thinly applying a plastic material such as polyester or nylon and then rubbing it with a non-woven fabric or the like. Further, as shown in FIG. 3, even if the plastic material is not applied, the material, shape, and
By appropriately setting the construction method, it is possible to rub the plastic material on the carbon protective film and adhere it in the form of stripes to form the alignment layer. In this case, it is preferable to carry out the treatment under reduced pressure in order to bring the magnetic tape raw material and the material to be rubbed into close contact with each other.

The lubricant is not particularly limited, but at least a polar group such as a carboxyl group, an amino group, a phosphoric acid group, a hydroxyl group, an ester group, and a fluoroalkyl group or a perfluoropolyether group are used. Fluorine-based lubricants having one or more are effective. For forming the lubricant layer in the present invention, a conventional coating method such as a bar coating method, a reverse roll coating method or a die coating method can be applied.

A more specific embodiment will be described below. (Embodiment 1) Oxygen was introduced onto a polyethylene terephthalate film having a thickness of 7 μm and having wavy projections and granular projections composed of a modified silicone in which silica fine particles having a particle size of 100 A are dispersed on a smooth surface and a thickener. On the other hand, a continuous oblique vapor deposition was performed by an electron beam method to obtain a Co film having a thickness of 180 nm.
An -O film was formed.

Then, a coating solution prepared by dispersing a mixture of carbon black and calcium carbonate in a ratio of 3: 2 by weight in a resin component in a ratio of 3: 2 by weight in polyurethane and nitrocellulose is provided on the side opposite to the vapor-deposited layer in a reverse roll system. It was applied with a coater and dried at a temperature of 110 ° C. to form a back coat layer with a film thickness of 0.7 μm.

Next, using a plasma CVD film forming apparatus as a protective film, a mixed gas of methane and argon was introduced as a source gas so that the degree of vacuum in the chamber was 0.2 torr, and a voltage of 1000 v was applied to the plasma. And a carbon protective film of 10 nm is formed by plasma polymerization,
A magnetic tape stock was produced.

Further, a coating solution in which a polyester resin is dissolved is applied by a reverse roll type coating machine and dried at a temperature of 110 ° C. to obtain a film having a thickness of 0.5 nm, and a nonwoven fabric mainly composed of polyester and polyethylene. The surface was rubbed to obtain an alignment layer.

Next, a lubricant containing a fluorine-containing carboxylic acid is applied to the surface of the alignment layer with a reverse roll coater, and the temperature is 75 ° C.
It dried at the temperature of and formed the lubricant layer. Next, the raw magnetic tape was cut into a width of 8 mm with a slitter to prepare a magnetic tape for 8 mm VTR.

(Embodiment 2) For the orientation layer, a coating liquid in which polyester resin is dissolved is applied by a reverse roll type coating machine and dried at a temperature of 110 ° C. to obtain a film having a thickness of 0.5 nm. The surface was rubbed with a nylon flocked cloth to obtain an alignment layer. A magnetic tape was produced under the same conditions as in Embodiment 1 except for the orientation layer.

(Embodiment 3) The orientation layer was formed by rubbing the surface of the carbon protective film with a non-woven fabric mainly composed of polyester or polyethylene and adhering the non-woven fabric material onto the carbon protective film. A magnetic tape was produced under the same conditions as in Embodiment 1 except for the orientation layer.

(Embodiment 4) The orientation layer was formed by rubbing the surface of the carbon protective film with a cloth in which nylon was flocked to adhere the nylon resin onto the carbon protective film. A magnetic tape was produced under the same conditions as in Embodiment 1 except for the orientation layer.

(Embodiment 5) The orientation layer was formed by rubbing the surface of the carbon protective film with a film of polyethylene terephthalate and depositing polyethylene terephthalate on the carbon protective film. A magnetic tape was produced under the same conditions as in Embodiment 1 except for the orientation layer.

(Comparative Example 1) A magnetic tape was prepared under the same conditions as in Embodiment 1 except that no orientation layer was provided on the carbon protective film.

(Comparative Example 2) A coating solution in which a polyester resin is dissolved is applied onto a carbon protective film by a reverse roll type coating machine and dried at a temperature of 110 ° C to form a film having a thickness of 0.5 nm. Only, the surface of the film was coated with the lubricant without rubbing. A magnetic tape was produced under the same conditions as in Embodiment 1 except for the above.

With respect to the magnetic tape prepared as described above and the magnetic tape stored in an environment of 40 ° C. and 80% RH for 1 month, the friction coefficient with respect to a stainless rod (surface roughness 0.4S) was measured.

For each tape, a commercially available 8 mm video deck (EV-S900 manufactured by Sony Corporation) was used to repeatedly run the magnetic tape 100 times in an environment of 40 ° C. and 80% RH, and the change in friction coefficient was examined. It was The measurement results are shown in (Table 1).

[0032]

[Table 1]

As is clear from (Table 1), in Comparative Example 1, the initial friction coefficient is high, and the friction coefficient is greatly increased even after storage at high temperature and high humidity and after repeated running. This is because the initial orientation of the lubricant is high due to the poor orientation of the lubricant, and because the adhesive strength of the lubricant to the protective film is weak, the lubricant on the surface of the protective film is lost due to repeated running and storage at high temperature and high humidity. It seems that the friction coefficient increased.

In Comparative Example 2, the initial friction coefficient is high, and the friction coefficient is greatly increased even after repeated running. However, the increase in the friction coefficient is relatively small only by storing in high temperature and high humidity. This is probably because the initial friction coefficient was high due to the poor orientation of the lubricant, and the lubricant was scraped off and lost due to the large load on the tape during repeated running. Further, it is considered that the lubricant was not lost because the adhesive force between the polyester resin and the lubricant was strong because the polyester resin and the lubricant did not change much just by storing in high temperature and high humidity.

In each of the magnetic tapes of Embodiments 1 to 5, the initial friction coefficient was small, and the friction coefficient hardly increased even after repeated running. Furthermore, even after repeated running after storage at high temperature and high humidity, the increase in friction coefficient was small compared to the comparative example.

Further, in Comparative Examples 1 and 2, the tape was partially stretched when repeatedly run at high temperature and high humidity, but in the first to fifth embodiments, the tape was not damaged at all.

[0037]

As can be seen from the above description, in the magnetic recording medium according to the manufacturing method of the present invention, the running stability due to the reduction of the friction coefficient and the increase in the friction coefficient due to repeated running and storage under high temperature and high humidity environment are suppressed. It is also possible to provide a high-quality magnetic recording medium having excellent durability and weather resistance.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a magnetic recording medium according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an alignment layer in Embodiments 1 and 2 of the present invention.

FIG. 3 is a schematic diagram showing an alignment layer according to Embodiments 3, 4, and 5 of the present invention.

FIG. 4 is a schematic diagram showing an outline of a processing apparatus used in the embodiment of the present invention.

FIG. 5 is an enlarged sectional view of a conventional magnetic recording medium.

[Explanation of symbols]

 1 Non-magnetic Substrate 2 Ferromagnetic Metal Thin Film 3 Protective Film 4 Orientation Layer 5 Lubricant Layer 6 Backcoat Layer 7 Magnetic Tape Fabric 8 Nonwoven Fabric

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location G11B 5/72 G11B 5/72

Claims (4)

[Claims] 1. A magnetic recording medium comprising a magnetic metal thin film, a protective film layer, an alignment layer and a lubricant layer, which are sequentially laminated on a non-magnetic support. 2. The magnetic recording medium according to claim 1, wherein the orientation layer is provided by rubbing a thin film layer mainly composed of an organic material provided on the thin film carbon layer with a non-woven fabric, a film or the like. A method of manufacturing a magnetic recording medium, comprising: 3. The magnetic recording according to claim 1, wherein the orientation layer is provided by rubbing the thin film carbon layer with a non-woven fabric, a film or the like mainly containing an organic material. Medium manufacturing method. 4. The method for producing a magnetic recording medium according to claim 3, wherein a portion where the thin-film carbon layer and the non-woven fabric, the film or the like contact each other is in a vacuum.