JPH08287459A - Magnetic recording medium manufacturing method and thin film manufacturing apparatus - Google Patents

Abstract

(57) [Summary] [PROBLEMS] The present invention relates to a method for manufacturing a magnetic recording medium having a magnetic recording layer of a ferromagnetic metal thin film, which is most suitable for a digital video tape recorder and a high definition video tape recorder, and a thin film manufacturing apparatus. It is an object of the present invention to obtain a magnetic recording medium that achieves both improvement of the still life after storage at high temperature and high humidity and reduction of the number of dropouts by forming a lubricant layer containing neither water nor solvent. A method of manufacturing a magnetic recording medium, wherein ultrasonic waves are applied to an evaporation source 8 for filling a lubricant 9 to scatter and evaporate lubricant particles to form a lubricant layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium and a thin film manufacturing apparatus, and more particularly to a method for manufacturing a magnetic recording medium excellent in weather resistance and dropout reduction. The present invention also relates to an apparatus for producing a thin film for evaporating organic substances such as a top coat layer of a magnetic recording medium.

[0002]

2. Description of the Related Art The magnetic layer of a ferromagnetic metal thin film type magnetic recording medium has a low hardness, is easily plastically deformed, and is easily abraded when it comes into direct contact with a magnetic head of a VTR which rotates at a high speed. Further, even when a hard carbon film is formed as a protective film on the magnetic layer, the protective film itself is brittlely broken by direct contact with the magnetic head of the VTR rotating at a high speed. Therefore, a lubricant layer is provided on the protective film to improve the lubricity between the magnetic recording medium and the magnetic head.

Generally, as a method for forming a lubricant layer, a solution of a lubricating substance such as fatty acid, fatty acid ester, fatty acid amide, etc., dissolved in an organic solvent is prepared, and the solution is used for spraying method, spin coating method and roll method. A coating method and the like, and a method of forming a lubricant layer by vacuum-depositing a lubricating organic substance which is a liquid at room temperature, as disclosed in JP-A-61-227230, are performed. There is.

Further, it has been found that the non-uniformity of the lubricant layer due to the uneven coating of the lubricant reduces the still life after storage in a high temperature and high humidity environment and increases the dropout, as disclosed in JP-A-63-90031, As disclosed in JP-A-64-33721 and JP-A-2-128320, a magnetic recording medium provided with a lubricant layer is subjected to a vacuum exhaust treatment, or when a lubricant layer is formed, it is ferromagnetic. Studies have been conducted such as placing a metal thin film under ultrasonic vibration, or continuously forming a lubricant layer by vacuum deposition while energizing a ferromagnetic metal thin film.

[0005]

However, in the above method, it is not possible to ensure the uniformity of the lubricant layer due to coating unevenness caused by moisture or residual solvent penetrating into the lubricant solution from the atmosphere. Also, when performing vacuum deposition, the molecular structure of the lubricant was changed by heat, and the performance of the lubricant itself could not be exhibited 100%.

The present invention pays attention to those problems, prevents moisture invading the lubricant solution from the atmosphere, does not use an organic solvent, and does not change the molecular structure of the lubricant by heat so that it can be kept constant. The method for producing a magnetic recording medium and the apparatus for producing a thin film, wherein a uniform lubricant layer having no coating unevenness is provided by a vacuum vapor deposition method at the vapor deposition rate.

[0007]

In order to solve the above-mentioned problems, a method of manufacturing a magnetic recording medium according to the present invention is a method of forming a lubricant by a vacuum vapor deposition method, wherein an evaporation source for filling the lubricant is superfluous. It is characterized in that the lubricant is evaporated by applying sonic vibration. Further, it is preferable to heat the evaporation source.

Alternatively, an evaporation source for holding the lubricant is provided,
A lubricant is supplied to the evaporation source, and ultrasonic vibration is applied to the evaporation source to evaporate the lubricant. Further, it is preferable to heat the evaporation source.

Further, the thin film manufacturing apparatus of the present invention is a thin film manufacturing apparatus for vacuum-depositing an organic substance, characterized in that it has ultrasonic vibrating means for applying ultrasonic vibration to the evaporation source. Further, it is characterized by having a heating means for heating the evaporation source.

Alternatively, it is characterized by comprising a metering pump for supplying a replenishing lubricant to the evaporation source and an ultrasonic vibration means for applying ultrasonic vibration to the evaporation source. Further, it is characterized by having a heating means for heating the evaporation source.

[0011]

According to the present invention, by imparting ultrasonic vibration to the evaporation source, directivity of ultrasonic energy in a certain direction is exerted on the lubricant, and the molecular kinetic energy of the lubricant molecule exceeds the surface tension of the lubricant. With this, the lubricant particles can be dispersed and evaporated at a constant speed without changing the molecular structure due to thermal decomposition to form a lubricant layer having a uniform film structure. Further, by supplying the lubricant to the evaporation source with a metering pump, the lubricant of the evaporation source can be kept constant and the ultrasonic vibration energy can be constantly applied to the surface of the lubricant. Therefore, the loss of ultrasonic vibration energy can be suppressed, and the lubricant particles can be more stably scattered and evaporated. Furthermore, by heating within the range where the lubricant is not thermally decomposed, the molecular kinetic energy of the lubricant can be greatly increased,
As a result, while improving the evaporation rate, it is possible to further prevent the temperature of the lubricant from decreasing due to latent heat of vaporization, and the lubricant particles scatter and evaporate at a constant speed to form a lubricant layer having a more uniform film structure. it can. Also, it does not require an organic solvent,
Since vapor deposition is performed in a vacuum, it is possible to provide a highly pure lubricant layer that does not contain residual solvent and that minimizes the intrusion of water into the lubricant. As a result, a lubricant layer having a uniform film structure with no coating unevenness can be obtained, the effect of the lubricant can be maximized, the still life after storage in a high temperature and high humidity environment is improved, and dropout can be reduced. Become.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 are views for explaining a method and an apparatus for manufacturing a magnetic recording medium of the present invention, and FIG. 3 is a view for explaining an example of a basic structure of a magnetic recording medium manufactured in this embodiment.

In FIG. 3, the non-magnetic substrate 1 is made of PET,
The ferromagnetic metal thin film layer 2 is made of a polymer film such as PEN, polyamide, or polyimide, and the ferromagnetic metal thin film layer 2 is made of Co-O or Co-Ni-.
O, Co—Cr, etc. are formed by the oblique vapor deposition method, and the hard carbon film layer 3 is formed by the plasma CVD method, the sputtering method, or the like.
The lubricant layer 4 is formed by applying a carboxylic acid, a carboxylic acid ester, a carboxylic acid amine, or the like, and the back coat layer 5
Is formed by applying a mixture of polyester resin, polyurethane resin and carbon, calcium carbonate, nitrocellulose or the like. In this embodiment, a PET film having a thickness of 5 to 10 μm is used as the non-magnetic substrate 1, and Co having a layer thickness of 0.1 to 0.2 μm is used.
A ferromagnetic metal thin film layer 2 made of —O was formed, a 10 nm hard carbon film layer 3 was formed on the ferromagnetic metal thin film 2 by a plasma CVD method, and a lubricant layer 4 was formed by 4 nm according to the present invention. A back coat layer 5 having a thickness of 0.5 μm is formed on the back surface to improve the running property.

(Embodiment 1) In the apparatus according to this embodiment shown in FIG.
Reduce the pressure to × 10 ^-5 Torr. The unwinding roll 16 is a magnetic recording medium before the formation of the lubricant layer 4 and is fed to the area where the lubricant layer 4 is formed, and the tension thereof is equivalent to 500 mm width and 5 kg.
It is controlled by f. The pass rolls 13 and 15 guide and rotate the magnetic recording medium. The main roll 14 is controlled at a constant speed (0.1 to 200 m / m) while controlling the temperature of the magnetic recording medium.
min) is controlled and conveyed. The take-up roll 17 is a magnetic recording medium after the lubricant layer 4 is formed, and its tension is 5
It has a width of 00 mm and is continuously wound at 5 kgf. The evaporation source 8 is filled with a fluorine-containing carboxylic acid C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH as a lubricant 9 and is subjected to ultrasonic vibration to scatter and evaporate. Ultrasonic transducer 7 is 5
It vibrates at a frequency of 0 kHz, and the ultrasonic transducer 7 and lubricant 9
The distance between the surfaces of is given by an integral multiple of 1/2 wavelength.
As a result, the maximum amplitude of ultrasonic vibration is given to the surface of the lubricant 9, the molecular kinetic energy of the lubricant molecules exceeds the surface tension of the lubricant 9 due to the directivity of the ultrasonic energy in a certain direction, and the lubricant particles scatter. ,Evaporate. The ultrasonic oscillator 21 provided outside the vacuum chamber has an output of 2 to 5 kW, which supplies ultrasonic vibration. Resistance heating wire 22
Applies external heating to the extent that the lubricant 9 is not thermally decomposed and promotes the molecular motion of the lubricant 9. A temperature controller 23 provided outside the vacuum chamber controls heating of the resistance heating wire 22. The closed container 12 prevents the evaporated particles of the lubricant from contaminating the magnetic recording medium in the vacuum chamber or the mechanical parts for transporting the magnetic recording medium. The crystal oscillator 10 detects the evaporation amount of the lubricant particles, and an evaporation rate meter 2 provided outside the vacuum chamber.
While displaying 0, the ultrasonic transmitter 21, the temperature controller 23, and the shutter opening / closing motor 18 are controlled.
The shutter 11 is opened after reaching a predetermined evaporation rate, and vapor deposition is started on the substrate.

The operation of the method for manufacturing a magnetic recording medium and the apparatus for manufacturing a thin film of the present invention configured as described above will be described with reference to FIG.

The magnetic recording medium before the formation of the lubricant layer 4 is one in which the hard carbon film layer 3 is formed on the ferromagnetic metal thin film layer 2 by the plasma CVD method, and the lubricant is formed on the magnetic recording medium. In order to form the layer 4, it is fed from the unwinding roll 16 in close contact with the main roll 14 through the pass roll 13. Here, the main roll 14 is set at 25 ° C. in order to keep the substrate temperature constant and align the molecular orientation of the vapor deposition film with respect to the substrate. Also, the lubricant 9 is the ultrasonic transducer 7
Is applied with ultrasonic vibration of 50 kHz, the shutter 11 is opened by the shutter opening / closing motor 18 at the time when the specified evaporation rate is reached, and the lubricant particles reach the substrate to form the lubricant layer 4. At this time, since the ultrasonic energy transmitted to the lubricant surface has a directivity in a certain direction and the molecular kinetic energy of the lubricant molecule exceeds the surface tension of the lubricant, the lubricant particles activated from the surface of the lubricant 9 Can be uniformly dispersed, and can be uniformly deposited on the hard carbon film layer to form a uniform lubricant layer 4.

(Embodiment 2) Except that ultrasonic vibration is applied to the lubricant 9 in (Embodiment 1), and at the same time the evaporation source 8 is heated by the resistance heating wire 22 to a temperature of 40 ° C. at which lubricant molecules are not thermally decomposed. The lubricant layer 4 is formed by the same operation as in (Example 1).

(Embodiment 3) The apparatus of the present embodiment shown in FIG. 2 has basically the same configuration as that of the apparatus shown in FIG. 1, so detailed description of the same components will be omitted. The replenishment lubricant 25 supplies the lubricant to the evaporation source 8 by the metering pump 24.

The operation of the method of manufacturing a magnetic recording medium and the apparatus of manufacturing a thin film of the present invention configured as described above will be described with reference to FIG.

In the first embodiment, the replenishment lubricant 25 is supplied into the evaporation source 8 by the metering pump 24, the surface height of the lubricant 9 is always kept constant, and the superconducting oil is transmitted to the lubricant surface. The lubricant layer 4 is formed by the same operation as in (Example 1) except that the sonic energy is kept constant.

(Embodiment 4) Except for applying ultrasonic vibration to the lubricant 9 in (Embodiment 3), at the same time as heating the evaporation source 8 by the resistance heating wire 22 to a temperature of 40 ° C. at which lubricant molecules are not thermally decomposed. The lubricant layer 4 is formed by the same operation as in (Example 3).

(Comparative Example 1) A lubricant layer 4 having a thickness of 4 nm was formed by a vacuum vapor deposition method using resistance heating (heating temperature 100 ° C.) without applying ultrasonic vibration to an evaporation source. Fluorine-containing carboxylic acid C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH was used as the lubricant.

(Comparative Example 2) Lubricant layer 4 by wet coating method
With a thickness of 4 nm. 2000 ppm of fluorine-containing carboxylic acid C ₅ F ₁₁ (CH ₂ ) ₁₀ COOH as a lubricant coating solution
Was used.

8 mm wide tape samples were prepared from the raw tapes obtained in each of the above Examples and Comparative Examples, and the number of dropouts and 40 ° C. 90% RH were stored for 1 week, and the measurement environment was 23 ° C. The still life was measured at 10% RH and 5 ° C. and 80% RH.

(1) Number of Dropouts The number of dropouts is 1 when the playback output is 16 dB or more continuously for 15 μs or more when a video signal is recorded and reproduced for 10 minutes using a stationary type 8 mm video deck.
It is the average value per minute.

(2) Still life Still life is the time until the reproduced signal drops by 3 dB from the initial output when the same portion is continuously reproduced using the pause mode of the stationary type 8 mm video deck.

The measurement results obtained are shown in (Table 1).

[0029]

[Table 1]

As is clear from (Table 1), if a vacuum vapor deposition is performed by using ultrasonic vibration during the formation of the lubricant layer, a uniform lubricant layer without coating unevenness can be formed, and the lubricant can be applied by a metering pump. By supplying the lubricant and keeping the position of the lubricant surface constant so as not to change the ultrasonic vibration energy on the surface, a more uniform lubricant layer can be obtained. As a result (Example 1) and (Example 3),
Compared with (Comparative Example 1) and (Comparative Example 2), the still life after high temperature and high humidity storage was dramatically improved, and the number of dropouts could be significantly reduced. Also, by heating below the thermal decomposition temperature of the lubricant, it is possible to prevent the temperature of the lubricant from decreasing due to latent heat of vaporization, improve the deposition rate, and efficiently form a uniform lubricant layer. Can be further improved. As a result, as in (Example 2) or (Example 4), a significant reduction in the number of dropouts is recognized as compared with (Example 1) or (Example 3).

In the above embodiments, the lubricant is used as a lubricant.
Fluorine-based carboxylic acid C_FiveF₁₁(CH₂) _TenWith COOH
Only the case was mentioned, but amine-based lubricants, carvone
In other lubricants including acid ester lubricants
However, the same effect can be obtained. Also lubricant
The present invention can also be applied to the formation of thin films using organic substances other than
It For example, liquid crystal alignment film, transparent electrode film, liquid crystal color film
The present invention is applied to the formation of capacitors and capacitors.
By using conventional electron beam evaporation and spin coating
Is expected to be stabilized.

[0032]

As described above, according to the present invention, it is possible to form a uniform lubricant layer having a low water-mixed concentration and containing no residual solvent by using ultrasonic vibrating means in a vacuum. It is possible to obtain a magnetic recording medium in which the above effect can be maximized, the still life after storage at high temperature and high humidity is dramatically improved, and the number of dropouts is significantly reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing an apparatus for manufacturing a thin film according to a first embodiment or a second embodiment of the present invention.

FIG. 2 is a diagram showing an apparatus for manufacturing a thin film according to a third embodiment or a fourth embodiment of the present invention.

FIG. 3 is a diagram showing an enlarged cross section of a metal type thin film magnetic recording medium that is an embodiment of the present invention.

[Explanation of symbols]

 1 Non-Magnetic Substrate 2 Ferromagnetic Metal Thin Film Layer 3 Hard Carbon Film Layer 4 Lubricant Layer 5 Backcoat Layer 6 Vacuum Chamber 7 Ultrasonic Transducer 8 Evaporation Source 9 Lubricant 10 Quartz Resonator 11 Shutter 12 Sealed Container 13 Pass Roll 14 Main Roll 15 Pass roll 16 Unwinding roll 17 Winding roll 18 Shutter opening / closing motor 19 Vacuum pump 20 Evaporation rate meter 21 Ultrasonic oscillator 22 Resistance heating wire 23 Temperature controller 24 Metering pump 25 Replenishing lubricant

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideyuki Ueda 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Noriyasu Echigo, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Yu Odagiri 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A method of manufacturing a magnetic recording medium in which a lubricant layer is formed by a vacuum vapor deposition method, wherein the lubricant is evaporated by applying ultrasonic vibration to an evaporation source for filling the lubricant. And a method for manufacturing a magnetic recording medium. 2. A method of manufacturing a magnetic recording medium according to claim 1, wherein a constant amount of lubricant is supplied to the evaporation source. 3. The method for manufacturing a magnetic recording medium according to claim 1, wherein the evaporation source is heated. 4. A thin-film manufacturing apparatus for vacuum-depositing an organic substance, which comprises ultrasonic vibrating means for applying ultrasonic vibration to an evaporation source. 5. The thin film manufacturing apparatus according to claim 4, further comprising a metering pump for supplying an organic substance to the evaporation source. 6. The thin film manufacturing apparatus according to claim 4 or 5, wherein the evaporation source has a heating means.