JPS61214132A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To produce the titled medium having excellent traveling property and durability by forming the coated film of fatty acid amide on the surface of the magnetic recording medium. CONSTITUTION:When the coated film of fatty acid amide is formed on the surface of a magnetic recording medium, the coated film is formed by vapor deposition while heating the surface of the magnetic recording medium at >=50 deg.C and the coated film having excellent vertical orientation of the molecule, namely the coated film of fatty acid amide having excellent lubricity, is formed even when the coated film-forming velocity is increased. The amide of a >=10C straight-chain fatty acid having >=100 deg.C m.p. such as myristic acid is most preferably used as the fatty acid amide. The vapor deposition means the thin- film forming method by vacuum deposition, ion plating, sputtering, ion-beam deposition, etc.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for manufacturing magnetic recording media such as magnetic disks and magnetic tapes, and particularly to a method for mass producing magnetic recording media with excellent runnability and durability. It relates to a manufacturing method.

[Prior art]

Continuous thin film media, in which a metal magnetic layer such as Go-Ni or Go-Cr or an oxide magnetic layer such as γ-Fe2O3 or Fe□04 is provided on a non-magnetic substrate, are attracting attention as high-density magnetic recording media. Active research continues.

However, at present, the mechanical durability of such continuous thin film media has not yet reached a satisfactory level despite the study of numerous protective films and lubricating materials. This was a major obstacle to practical application.

On the other hand, in the mechanical field, fatty acid amides have been known to have excellent anti-wear and lubricating effects, but when applied to continuous thin film media, sufficient durability improvement effects have not been obtained.

[Problem that the invention seeks to solve]

As mentioned above, one of the reasons why a sufficient durability improvement effect cannot be obtained when a fatty acid amide is applied to a continuous thin film type medium is considered to be as follows.

In other words, fatty acid amide has an amino group attached to the end of the molecule that strongly adsorbs to the object to be lubricated, and when the molecules are oriented perpendicular to the film surface and cover the surface, it exhibits effective anti-wear and lubricating effects. .

If the surface of the object to be lubricated cannot be sufficiently covered, its effectiveness will be drastically reduced.

For example, in Published Patent Publication No. 113303 of 1972,
A method of forming a fatty acid metal salt film using a vacuum evaporation method has been disclosed, but when this method is actually carried out,
When attempting to form an effective film, the film formation rate becomes extremely slow, making it difficult to put it into practical use.

Furthermore, if the film formation rate is increased in this method, the vertical orientation of the molecules will be insufficient, and the wear resistance and lubricity will deteriorate, making it impossible to obtain sufficient effects.

Therefore, it has been difficult to mass-produce magnetic recording media with excellent durability using the above film forming method.

An object of the present invention is to provide a manufacturing method capable of solving the problems of the prior art as described above and mass producing magnetic recording media with excellent running performance and durability.

[Means for Solving the Problems] The present invention was made based on the experimental finding that the wear resistance and lubricity of a coating significantly change depending on the temperature at which the coating is formed. When forming a fatty acid amide film on the surface of a medium, at least the surface of the magnetic recording medium is heated to 50°C or higher before the film is formed by vapor deposition, so that even if the film formation rate is increased, the molecular The structure is such that it is possible to form a film with good vertical orientation, that is, a fatty acid amide film with excellent lubricity.

In the present invention, preferable fatty acid amides include those having a melting point of 100° C. or higher and especially linear fatty acids having 10 or more carbon atoms, such as amides of myristic acid, palmitic acid, stearic acid, behenic acid, and the like.

Note that even if a simple fatty acid other than a fatty acid amide is used, such as palmitic acid, oleic acid, stearic acid, behenic acid, etc., if a film is formed by vapor deposition while heating the surface of the magnetic recording medium, a good vertical However, since such fatty acids have a low melting point, the membrane easily breaks due to the frictional heat caused by sliding with the magnetic head, and its performance as a protective lubricant film is impaired. It is enough.

In addition, in the present invention, the vapor deposition method includes a vacuum evaporation method, an ion blating method, a sputtering method,
This refers to a thin film forming method such as ion beam deposition method.

The fatty acid amide coating may be formed directly on the ferromagnetic layer provided on the nonmagnetic substrate or after surface treatment such as oxidation or nitridation. It is also possible to form a layer on which a hard inorganic protective layer is provided.

In any case, when forming the above-mentioned fatty acid amide coating, it is necessary to form the coating while heating the magnetic recording medium to a surface temperature of at least 50° C. or higher.

[Embodiments of the invention]

Example 1 A film thickness of 0.2 mm was deposited on a glass substrate with a plate thickness of 2 mm and a diameter of 75 mm.
A G o -Cr film of - was formed by high-frequency sputtering, and stearamide was vapor-deposited to a thickness of 120 mm by resistance heating while heating the surface of the recording medium to various temperatures.

The durability of the Go-Cr thin film medium thus obtained was evaluated by a spherical sliding test.

The material of the slider was sapphire, and the measurement conditions were a slider pressing load of 6 g and a circumferential speed of 2 m/sec.

The results are shown in Table 1.

Note that the unit of spherical sliding strength indicates the cumulative number of rotations of the recording medium until the output of the recording medium decreases to 80% of the initial value.

Table 1 As can be seen from Table 1 above, if the substrate temperature during behenic acid amide vapor deposition is 50° C. or higher, it is possible to significantly improve the sliding resistance.

Example 2 A thin film was formed using a PET (polyethylene terephthalate) film having a thickness of 12 mm as a substrate using a vacuum evaporation apparatus shown in FIG.

In FIG. 1, a Co--Ni alloy provided from an evaporation source 6 is deposited on a base film 3 supplied from a roll 1, and then stearamide from a crucible 5 is continuously deposited.

Note that the film formation rate of the Co-Ni alloy thin film is ioo.

person/sec, the film formation rate of stearic acid amide coating is 5
0 people/see, and the film thickness is 90% for the Go-Ni alloy thin film.
0 people received the stearic acid amide coating, and 45 people received the stearic acid amide coating.

Also, the can temperature is 25℃, 40℃, 50℃, 60℃,
Experiments were conducted with the temperature changed to 80°C.

FIG. 2 shows the results of a still playback test conducted to evaluate the durability of the magnetic recording medium produced as described above.

As can be seen from FIG. 2, when the can temperature is increased, the still regeneration life is improved, and it is understood that the improvement in the still regeneration life is particularly remarkable when the can temperature is 50° C. or higher.

〔Effect of the invention〕

As explained above, in the present invention, when forming a fatty acid amide coating on a magnetic recording medium, the coating is formed by a paper deposition method while heating the surface of the magnetic recording medium to 50°C or higher, thereby improving wear resistance. It became possible to obtain a fatty acid amide coating with significantly improved lubricity.

Furthermore, in the present invention, as is clear from the above examples, the properties of the film do not deteriorate even if the film formation rate is considerably increased, so that magnetic recording media with excellent wear resistance and lubricity can be mass-produced. It is also possible to do this, and has extremely excellent practical effects.

[Brief explanation of drawings]

FIG. 1 is an example of the apparatus used in the manufacturing method of the present invention, and FIG.
The figure shows the results of a still playback test. <Explanation of symbols>

Claims (1)

[Claims] The surface of the magnetic recording medium, which has only a ferromagnetic layer on a nonmagnetic substrate, or a ferromagnetic layer and an inorganic protective layer thereon, is heated to a temperature of 50° C. or higher while being heated by vapor deposition method. A method for manufacturing a magnetic recording medium, comprising forming a fatty acid amide coating on the surface.