JPH0237525A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance corrosion resistance and durability by regulating the min. incident angle by a mask and forming a 1st vapor deposited film, then providing a slit to the middle part of the mask and forming a 2nd vapor deposited film on the 1st vapor deposited film. CONSTITUTION:The evaporating vapor flow of a magnetic metallic material which is evaporated by heating is deposited by evaporation on a nonmagnetic base 25 while the incident angle thereof with the normal of the nonmagnetic base 25 traveling on an can 11 is controlled by the mask 12, by which a thin magnetic film is formed. The slit is provided to the middle part of the mask 12 and since the can 11 rotates in the direction shown by T in the figure, the evaporating vapor flow S1 regulated of the incident angle by one end of the mask 12 is formed by vapor deposition as the 1st vapor deposited film on the nonmagnetic base 25 and the evaporating vapor flow S2 regulated of the incident angle by the slit of the mask 12 is formed by vapor deposition as the 2nd vapor deposited layer on the 1st vapor deposited layer. The evaporating vapor flow S2 is formed as a rust preventive layer on the 1st vapor deposited layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a magnetic recording medium in which a magnetic i-film is formed on a non-magnetic support by vacuum deposition.

[Summary of the invention]

The present invention provides a method for manufacturing a magnetic recording medium in which a magnetic thin film is formed on a non-magnetic support, in which a first vapor deposition layer is formed by defining a minimum incident angle using a mask, and a slit is formed in the middle of the mask. established,
By forming a second vapor deposition layer on the first vapor deposition layer, a magnetic recording medium with excellent corrosion resistance and durability is manufactured.

[Conventional technology]

Traditionally, magnetic recording media have been made using magnetic paints in which magnetic powders such as oxide ferromagnetic powders or metal magnetic powders are dispersed in organic binders such as vinyl chloride-vinyl acetate copolymers, polyester resins, and polyurethane resins. Coating-type magnetic recording media, which are produced by coating and drying on a support, are widely used.

On the other hand, with the increasing demand for high-density magnetic recording, ferromagnetic metal materials such as Co-Ni alloys can be made into polyester by plating or vacuum thin film forming technology (vacuum evaporation method, sputtering method, ion blating method, etc.). A so-called ferromagnetic metal thin film type magnetic recording medium, which is directly deposited on a non-magnetic support such as a film or a polyimide film, has been proposed and is attracting attention. This ferromagnetic metal thin film type magnetic recording medium not only has excellent coercive force and squareness ratio, and has excellent electromagnetic conversion characteristics at short wavelengths, but also has the ability to make the thickness of the magnetic layer extremely thin, making recording demagnetization possible. It has many advantages, such as extremely small thickness loss during playback and reproduction, and the ability to increase the packing density of the magnetic material since there is no need to mix an organic binder, which is a non-magnetic material, into the magnetic layer.

However, since the magnetic layer is made of metal material,
During storage, especially when exposed to high temperature and high humidity, corrosion tends to occur on the surface of the magnetic layer, resulting in problems such as the saturation magnetization, coercive force, etc. being deteriorated orally. In addition, in general, in a ferromagnetic metal thin film type magnetic recording medium, a ferromagnetic metal thin film, which is a magnetic layer, is formed by oblique evaporation, and the minimum incident angle is a single layer at a high incidence angle of 45° to 60°. It is vapor deposited.

In this case, the formed ferromagnetic metal thin film has a column structure grown in the direction of incidence of the vapor flow, so it is weak against rust and has insufficient corrosion resistance. Therefore, many attempts have been made to improve the corrosion resistance, such as surface treatment of the magnetic layer, application of rust preventives, improvement of the film structure of the medium, and improvement of the film composition.

However, although the above-mentioned surface treatment of the magnetic layer, application of a rust preventive agent, improvement of the film composition, etc. are effective for corrosion resistance, for example, when applying a rust preventive agent, the non-magnetic rust preventive layer Since the magnetic tape comes into contact with the magnetic head through the magnetic tape, the electromagnetic conversion characteristics may deteriorate due to so-called spacing loss.Furthermore, other methods may also cause the electromagnetic conversion characteristics to deteriorate. In particular, these methods are fraught with problems in view of the current situation where recording wavelengths are becoming shorter with the trend toward higher density recording.

In view of these circumstances, the applicant has filed the
Using a device such as that disclosed in Japanese Patent No. 429, a proposal has been made regarding the improvement of the film structure of the medium. The above-mentioned apparatus has a much simpler structure and higher manufacturing efficiency than the conventional method using a two-can type continuous vapor deposition apparatus.

[Problem to be solved by the invention]

However, the above device is on the 2nd floor! This structure is very effective in manufacturing magnetic recording media and has excellent durability.
Because the second vapor deposition film is obliquely vapor-deposited just before dawn, the film structure of the second vapor-deposited film has a column structure oriented in the incident direction. For this reason, the second vapor deposited film has a structure in which voids exist between the columns and air (oxygen) easily passes through, and is less effective as a protective film against corrosion such as rust of the first vapor deposited film.

Therefore, an object of the present invention is to provide a method for manufacturing a magnetic recording medium having a 2ii structure, and also to improve the corrosion resistance, natural properties, and manufacturing efficiency of the magnetic recording medium.

[Means to solve the problem]

The present inventor has proposed a method for manufacturing a magnetic recording medium in which a magnetic thin film is formed on a non-magnetic support by oblique deposition, in which the minimum incident angle is controlled by a mask. A slit is provided in the middle of the mask, and a first vapor deposition layer is formed in a specified manner.
The method is characterized in that a second vapor deposited layer is formed on the vapor deposited layer.

Therefore, according to the present invention, it is possible to provide a manufacturing method with high manufacturing efficiency and corrosion resistance.

A magnetic recording medium with excellent durability can be obtained.

[Effect]

When forming a deposited layer on a nonmagnetic support, a magnetic recording medium having a two-layer structure can be manufactured in one step by providing a slit in the middle of the mask. In addition, since the second vapor deposited film has a dense structure in which the column structure does not form vertically oriented voids, it is difficult for air (particularly oxygen) to pass through and is resistant to rust. Therefore, it acts as a rust preventive film with excellent corrosion resistance for the first vapor deposited film, which is a magnetic layer.

〔Example〕

Embodiments of a method for manufacturing a magnetic recording medium according to the present invention will be described with reference to the drawings.

When carrying out the method for manufacturing a magnetic recording medium according to this embodiment, a vacuum evaporation apparatus as shown in FIG. F, for example, is used.

That is, the above-mentioned device includes a can (11) in which the non-magnetic support (15) runs, a mask (12) having a slit in the middle, and a crucible (not shown) provided with a metal magnetic material as an evaporation source. ), an oxygen introduction pipe (14), and a supply roller, take-up roller, chamber, and exhaust system (not shown).

This is a vacuum evaporation device that uses an oblique evaporation method and is equipped with an electron gun and the like.

The non-magnetic support (15) travels at a predetermined speed on the can (11) rotating in the direction shown by T in the figure, and at the same time the metal magnetic material is exposed to the electron beam of the electron gun. It is heated and evaporated. The evaporated vapor flow of the metal magnetic material heated and evaporated changes the incident angle with respect to the normal line (represented by the dotted chain line in the figure) of the non-magnetic support (I5) running on the can (11) through the mask. (12) is deposited on the non-magnetic support (15) to form a magnetic thin film.

At this time, since a slit is provided in the middle of the mask (12) and the can (11) is rotating in the direction indicated by T in the figure, the angle of incidence is regulated at one end of the mask (12). The evaporated vapor stream Sl is deposited as a first deposited layer on the non-magnetic support (15) and is applied to the mask (12).
) The evaporated vapor flow S2 whose incident angle is regulated by the slit is
A second vapor deposition layer is formed by vapor deposition on the previously formed first vapor deposition layer.

Here, since the first deposited layer is obliquely deposited as a magnetic layer, the maximum incident angle θIH of the evaporated vapor flow S1 is 70°.
The minimum incident angle θIL is regulated by the mask (12), and the angle is in the range of 30° to 80°.The incident angle is controlled by the slit of the mask (12). The evaporative vapor flow S2 is
Prevention # on the vapor deposited layer! Since it is formed as a layer, it is formed as a dense film with vertical alignment as described above.

Therefore, the maximum angle of incidence θ2H of the evaporated vapor flow S2 is 60
゛The minimum incident angle θ2L is 30°~
The range is 60°.

Further, the can (11) has a cooling function (not shown) that can control its surface temperature to around 0°C, and the metal magnetic material that is heated and evaporated by the electron beam from the electron gun is heated and evaporated by the electron beam from the electron gun. Vapor deposition can be performed by controlling the evaporation rate as desired. A small amount of oxygen is introduced from the oxygen introduction tube (14), and the first magnetic thin film is formed by vapor deposition in the oxygen atmosphere. By controlling the amount of introduced oxygen, a predetermined oxygen concentration gradient is created. It is also possible to form a magnetic thin film having .

Furthermore, although the vacuum evaporation method used in this example is an electron beam evaporation method, various other vacuum evaporation methods are applicable. For example, any vacuum deposition method such as resistance heating evaporation, induction heating evaporation, ion beam deposition, ion plating, laser beam evaporation, or arc discharge evaporation can be performed, but the coercive force of the magnetic recording medium, The methods used in this example, such as electron beam evaporation and ion brating, are used to improve magnetic properties such as anisotropic magnetic field and to obtain a high deposition rate, and also improve operability and mass production. From an industrial point of view, electron beam evaporation is the most popular method.

The magnetic recording medium produced by the method described above includes a first vapor deposition layer (2) formed on a nonmagnetic support (1) as shown in FIG. ) with a second deposit N(3) formed on top.

In this example, the non-magnetic support (15) has a thickness of 1
Although a 0 μm polyethylene terephthalate film was used, any material conventionally used as a nonmagnetic support for this type of magnetic recording medium can be used. For example, polyesters such as polyethylene naphthalate, polyolefins such as polyesters, cellulose derivatives such as cellulose triacetate, polymeric substances such as polycarbonate, polyvinyl chloride, and polyamide can be used. Furthermore, prior to forming the magnetic recording layer, these nonmagnetic supports may be subjected to surface treatment or pretreatment for the purpose of facilitating adhesion, improving flatness, coloring, preventing static electricity, imparting wear resistance, etc. .

On the other hand, in this example, Co was added to the metal magnetic material as the evaporation source.
C consisting of 80 parts by weight and 20 parts by weight of Nt.

Although a Ni alloy was used, any other metal magnetic material that is normally used in this type of magnetic recording medium can be used. For example, Go, C
o-PL alloy, Co-N1-pt alloy, Fe-Co
alloy, Fe-Co-Ni alloy, Fe-Go-B alloy, Fe-C.

-Ni-B alloy, GO-(u alloy, Fe-Cu alloy, Co-Au alloy, Mn-B1 alloy, Mn-
A II alloy, Fe Cr alloy, Ni-Cr
Metal magnetic materials such as Fe--Co--Cr-based alloys, Co--Ni--Cr-based alloys, etc. can be used.

Furthermore, since the first vapor deposition layer and the second vapor deposition layer are vapor deposited simultaneously and from the same material as described above, the adhesion between the respective layers is high.

A sample tape was produced by the method of the above-mentioned example.

Two types of sample tapes (Sample 1, Sample 2)
) was produced, and as a comparative example of Sample 1 and Sample 2, a sample tape (Comparative Example 1) in which the second vapor deposited layer was not formed was produced. The conditions for producing the sample tape thus produced are shown below.

sample 1 Maximum incident angle of first vapor deposited layer First vapor deposited layer minimum incident angle Second vapor deposited layer maximum incident angle Second vapor deposited layer minimum incident angle Film thickness of the first vapor deposition layer... Film thickness of second vapor deposition layer... Tape speed... θIH・ θIL・ θ2H・ θ2L・ ヱ±n肚i First vapor deposited layer highest incident angle θ1■・ 90.

45.

20.

10.

2000 people 250 people 15m/min ・9°0.

First vapor deposited layer minimum incident angle θIL・ Second vapor deposited layer highest incident angle θ2H・ Second curtain NNk low incident angle θ2L・ Film thickness of first vapor deposition layer... Thickness of second vapor deposited layer... Tape speed... 45.

20.

10.

2000 people 500 people 15 m/min ratio m First vapor deposited layer highest incident angle θIH...90° First vapor deposited layer lowest incident angle θIL...45° First vapor deposited layer thickness...
...2000 people tape speed...15
In order to evaluate the corrosion resistance of the sample tape of m/min or more, the following corrosion resistance test was conducted without applying a rust preventive agent to the surface of the tape. The above test was conducted under the conditions of being left in an atmosphere with a temperature of 40 ° C and a relative humidity of 90% for 3 days.
After the test, rust on the tape surface was observed. The results are shown in Table 1. Table 1 also shows the magnetic properties when producing the sample tape. Here, in Table 1, ○ indicates that no rust is observed on the tape surface, Δ indicates that some rust is observed, MU indicates that a slight amount of rust is observed, and × indicates that a lot of rust is observed. shows.

From Table 1, it can be confirmed that Samples 1 and 2 have a substantially satisfactory rust-preventing effect against rust, and no deterioration in magnetic properties was observed.

Furthermore, the tape of Comparative Example 1 was found to have poor corrosion resistance since rust was observed on its surface.

Next, as another example, as shown in FIG. A medium was prepared.

In this example, the second vapor deposition layer becomes an oxide film by installing an oxygen introduction pipe (14b) near the slit of the mask (12) and introducing a large amount of oxygen when forming the second vapor deposition layer. Therefore, the second vapor deposited layer becomes a protective film with a high rust prevention effect. As described above, the second evaporated layer is an oxide film, so it is a nonmagnetic film. Further, according to this embodiment, the durability of the magnetic recording medium can be improved.

A sample tape was produced by the method of the above-mentioned example (in which the second vapor deposited film was an oxide film).

Three types of sample tapes (Sample 31, Sample 4, and Sample 5) were produced, and as a comparative example of Samples 3 to 5, a sample tape in which the second vapor deposition layer was not formed (Comparative Example 2) was produced. The manufacturing conditions and magnetic properties of the manufactured sample tape are shown below.

Sample 3 First vapor deposition i highest incident angle θIH First vapor deposited layer minimum incident angle θIL Second vapor deposited layer highest incident angle θ2H Second vapor deposited layer minimum incident angle θ2L Film thickness of first vapor deposition layer... Thickness of second vapor deposited layer... Tape speed... 90.

45.

20.

10.

2000 people 100 people 15m/division 221 and 1 First vapor deposited layer maximum angle of incidence θ1 ■...90'' First vapor deposition layer minimum incidence angle θIL...45° Second vapor deposition layer maximum incidence angle θ
2H Second vapor deposition layer minimum incident angle θ2L First vapor deposition layer thickness... Second vapor deposition layer thickness... Tape speed... Sample 5 First vapor deposition layer maximum Incident angle θ1, first vapor deposited layer, minimum incident angle θIL, second vapor deposited layer, maximum incident angle θ2, second vapor deposited layer, minimum incident angle θ2L, first vapor deposited layer film thickness... Second Thickness of the vapor deposited layer...Tape speed...This MJML Maximum incident angle of the first vapor deposited layer 011 - Minimum incident angle of the first vapor deposited layer θIL - Thickness of the first vapor deposited layer ...Tape speed...20.

10.

2000 people 300 people 15m/min 90' 45.

20.

10” 2000 people 500 people 15m/min 90.

45.

Sample tapes were produced by 2,000 people at a speed of 15 m/min or more, and Table 2 shows the magnetic properties at the time of production.

In addition, a test was conducted on the sample tape to evaluate its corrosion resistance without applying a rust preventive agent. The above test was conducted under the condition that the tape was left in an atmosphere at a temperature of 40°C and a relative humidity of 90% for 3 days, and rust on the tape surface was observed after the test. Furthermore, as a durability test of the sample tape, still durability and shuttle durability were also measured. Still durability evaluates the attenuation time until the output decreases by 3 dB in a pause state, and shuttle durability is the attenuation of the output after 100 shuttle runs at room temperature and pressure after applying lubricant to the tape surface. was evaluated. Table 3 shows the results of the still durability, shuttle durability, and rust observation. Here, O in Table 3 indicates that no rust is observed on the tape surface,
MU indicates that a little more rust is observed, and × indicates that more rust is observed.

Sample 3 in the tests listed in Table 2 and above. No rust was observed in either Sample 4 or Sample 5, and in Comparative Example 1, rust was observed on the surface and no deterioration in magnetic properties was observed.

Furthermore, from Table 3, it can be seen that forming a second vapor deposition layer into which oxygen is introduced is effective in improving still durability, and that the formation of a second vapor deposition layer also improves shuttle durability. is found to be effective in improving this.

[Effects of the Invention] As is clear from the above description, by using the manufacturing method of the present invention, a two-layer magnetic recording medium can be easily obtained with high manufacturing efficiency. Furthermore, by using this manufacturing method, it is possible to provide a magnetic recording medium that is resistant to rust and has excellent durability.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a vacuum evaporation apparatus used in carrying out an embodiment of the present invention. FIG. 2 is an enlarged sectional view of a main part showing an example of the structure of a magnetic recording medium manufactured using the manufacturing method of the present invention. FIG. 3 is a schematic diagram showing another example of the vacuum evaporation apparatus. 1...Nonmagnetic support 2...First vapor deposition layer 3...Second vapor deposition layer 12...Mask

Claims (1)

[Claims] A method for manufacturing a magnetic recording medium in which a magnetic thin film is formed on a non-magnetic support by oblique vapor deposition, comprising: forming a first vapor deposition layer by defining a minimum incident angle using a mask; A slit is made in the middle of the
A method for manufacturing a magnetic recording medium, comprising forming a second vapor deposition layer on the first vapor deposition layer.