JPH056739B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to magnetic recording media such as magnetic tapes and magnetic disks, particularly those having recording layers on both sides of a substrate. Conventional configurations and their problems Traditionally, magnetic recording media have been made of γ-Fe 2 O 3 or Co-doped γ-Fe ₂ O ₃ on a polymer substrate or aluminum substrate.
So-called coating-type materials, in which powdered magnetic materials such as oxide magnetic powders such as CrO ₂ or ferromagnetic alloy powders are dispersed in organic binders such as polyurethane resins, coated and dried, are widely used in practice. There is.
However, in recent years there has been a strong desire to improve recording density, and the conventional coated type has reached its limit in improving recording density, and the high output characteristics of the metal thin film type at short wavelengths are attracting attention, and efforts to commercialize such media are active in various fields. It is becoming more and more. Since metal thin film magnetic recording media differ from conventional coating-type magnetic recording media in terms of construction methods, there are still many problems that need to be solved before they can be put into practical use. Above all, it is important to bring into practical use a manufacturing method for a tape that simultaneously satisfies both the ability to maintain a good envelope through repeated use and the ability to have an excellent C/N ratio.
This is an important issue. Purpose of the Invention The present invention provides a magnetic material that has excellent practical durability and can maintain a good envelope, which is made by disposing a metal thin film magnetic recording layer on both sides of a substrate and disposing an organic vapor deposited layer on each of the magnetic recording layers. An object of the present invention is to provide a manufacturing method that can stably produce a recording layer medium. Structure of the Invention In the method for manufacturing a magnetic recording medium of the present invention, first and second cylindrical rotary cans for cooling and transporting a strip-shaped substrate are disposed with their winding sides inward, and the vapor flow An evaporation source for forming a metal thin film magnetic recording layer is arranged so as to face the winding side of the first and second rotation cans, and the strip-shaped substrate is moved from the first rotation can to the second rotation can. The present invention is characterized in that an organic material evaporation source is provided near the sending side of the first and second rotating cans, and a metal thin film magnetic recording layer and an organic material vapor deposition layer are laminated on both surfaces of the substrate. The substrate in the present invention is a polymer substrate itself, a polymer substrate with nonmagnetic layers formed on both sides, or a polymer substrate with soft magnetic layers formed on both sides. The polymer substrate must be made of polyethylene terephthalate, polyethylene naphthalate, polyamide, polyimide, polycarbonate, etc., and must have a smooth surface, with a center line average roughness of 200 Å or less, preferably 100 Å or less, to prevent dropouts. It is necessary to suppress the connecting abnormal protrusions as much as possible. Although there is no particular limit to the thickness of the substrate, it is possible to use techniques such as obtaining a finely roughened surface using a coating method or depositing fine particles on the surface, mainly to improve handling during the manufacturing process. This will also be done as necessary. Metal thin film magnetic recording layers are broadly classified into so-called in-plane magnetized films whose easy axis of magnetization is parallel to the substrate surface, and perpendicular magnetized films whose axis of easy magnetization is perpendicular to the substrate surface. There are a wide variety of material configurations that can be used for each, and there are no limitations from the perspective of the materials specifically used in the present invention. However, depending on the application, the environment in which it will be used will be wide-ranging, so sufficient consideration should be given to corrosion resistance.
alloy, Co-Ni-Cr alloy, Co-Ni alloy,
A preferable material is a Co-Ni-O alloy.
The non-magnetic layer and soft magnetic layer used as needed can also be selected with consideration to adhesion strength to the substrate, corrosion resistance, etc., and preferred materials include titanium, chromium, molybdenum, and permalloy. The organic vapor deposited layer used in the present invention may be made of a single material such as a fatty acid, a fatty acid amide, or a fatty acid ester, or a mixture of a plurality of materials, and a rust preventive agent may be used to further improve the corrosion resistance of the metal thin film magnetic recording layer. Of course, it is also possible to blend together with a lubricant, and the organic vapor deposited layer herein also includes a plasma-polymerized thin film of fluorocarbons. Regardless of whether the manufactured magnetic recording medium is in the form of a tape or a disk, it is important that it be flat in order to obtain a stable envelope, and it is not necessary to insist on the same material and thickness on both sides. but,
When using different materials as constituent elements, it is necessary to find conditions that will result in an even finished product. Incidentally, since the organic vapor deposited layer does not have internal stress that affects the flatness described above, it is difficult from a manufacturing perspective to use different material compositions in order to compensate for the surface properties caused by mutual transfer. It's easy. Basically, there is a single organic tank, and each thin film is continuously formed inside. The metal thin film magnetic recording layer can be formed by vacuum deposition, sputtering, ion plating, reactive deposition, electric field deposition, ion beam deposition, or the like. Since polymer substrates have low heat resistance, they are susceptible to thermal deformation and thermal damage during vapor deposition.
Therefore, it is necessary to move the cooling support along the cooling support, and if the cooling support is fixed, there will be problems such as scratches on the substrate.
Cylindrical rotating cans, driven metal belts, etc. are used. Unlike the formation of metal thin films, organic vapor deposition has less thermal influence, but film thickness control is important.
Therefore, the substrate is cooled and the source of re-evaporation is suppressed. The substrate winding system must be configured to allow thin film formation on both sides. This is important to prevent increases in dropouts and deterioration of durability that would occur if one side of the board was constructed in separate vacuum chambers or by flipping the board over in the same vacuum chamber. In order to obtain an optimal atmosphere for forming a thin film, the inside of the vacuum chamber can be divided and the exhaust system configuration, gas introduction system configuration, voltage introduction system configuration, etc. for controlling the atmosphere can be selected as appropriate. Description of Examples Hereinafter, the manufacturing method of the present invention will be described based on drawings showing specific examples. FIG. 1 is a cross-sectional view of a magnetic recording medium manufactured by the manufacturing method of the present invention, in which 1 is a polymer substrate serving as a base, 2 and 3 are metal thin film magnetic recording layers, each of which is one side of the polymer substrate 1. is formed directly on one side and the other side. 4 and 5 are metal thin film magnetic recording layers 2,
This is an organic substance vapor deposited layer formed on each surface of No. 3. Note that the polymer substrate here has a band-like form. FIG. 3 shows a manufacturing apparatus capable of manufacturing a magnetic recording medium having the cross-sectional structure shown in FIG. 8 is the exhaust system 9,1
This is a vacuum chamber that is maintained in a vacuum state by a vacuum chamber, and the following system is housed inside this chamber. That is, first and second cylindrical rotary cans 11 and 12 are arranged in parallel so that they rotate in the directions of arrows A and B, and their winding sides are on the inside, respectively;
Evaporation source containers 13, 14, 15, a feeding shaft 16 for the polymer substrate 1, and a winding shaft 17 for the polymer substrate 1
etc. are stored. To explain the internal structure of the vacuum chamber 8 in detail, the polymer substrate 1 set on the delivery shaft 16 is first inputted from the winding side of the cylindrical rotating can 11, and is then passed through the free roller 18 and expander roller (not shown). , is inputted to the winding side of the cylindrical rotary can 12 via a dancer roller (not shown), and is wound onto the winding shaft 17. The evaporation source container 13 is disposed below the winding side of the cylindrical rotary cans 11 and 12 so that the vapor flow 19 is directed toward the winding side of the cylindrical rotary cans 11 and 12, and the evaporation source container 13
are arranged near the delivery side of the cylindrical rotary cans 11 and 12, respectively. A ferromagnetic metal material 20 for forming the metal thin film magnetic recording layers 2 and 3 is placed in the evaporation source container 13, and a water-cooled copper hearth or a refractory crucible is used as the evaporation source container 13. The vapor flow 19 is obtained by heating the ferromagnetic metal material 20 by means of a beam (not shown). Although FIG. 3 shows an example in which a high coercive force is obtained by oblique evaporation, other measures are naturally taken to obtain a perpendicularly magnetized film. A fixed mask 21 is used to limit the minimum incident angle for oblique evaporation. 22 is an anti-adhesion plate. The evaporation source containers 14 and 15 are hollow and made of, for example, quartz, and the amount of evaporation is controlled by circulating a heating medium to control the temperature. Organic materials 23 and 24 for forming organic substance vapor deposition layers 4 and 5 are placed in the evaporation source containers 14 and 15. 25 is a crystal oscillator for monitoring the film thickness of the organic substance vapor deposited layers 4 and 5. With this configuration, the metal thin film magnetic recording layer 2 is first formed on the polymer substrate 1 on the winding side of the cylindrical rotating can 11 by the vapor flow 19 . The polymer substrate 1 on which the metal thin film magnetic recording layer 2 is formed on one side is formed with an organic substance evaporation layer 4 on the metal thin film magnetic recording layer 2 by the organic material 23 on the sending side of the cylindrical rotating can 11. . A polymer substrate 1 on which a magnetic recording layer 2 and an organic substance evaporation layer 4 are formed.
passes through the free roller 18 etc. to the cylindrical rotating can 1
A metal thin film magnetic recording layer 3 is formed on the other side of the polymer substrate 1 by a vapor flow 19 on the winding side of 2, and then a metal thin film magnetic recording layer 3 is formed on the other side of the polymer substrate 1 by an organic material 24 on the delivery side of the cylindrical rotary can 12. An organic substance vapor deposition layer 5 is formed on the recording layer 3 . Metal thin film magnetic recording layers 2 and 3 with the same evaporation flow 19
Therefore, it is possible to reliably obtain metal thin film magnetic recording layers 2 and 3 having the same thickness. Further, a metal thin film magnetic recording layer 3 is provided on the opposite side of the organic substance vapor deposited layer 4 which is continuously formed by the vapor source container 14 in a vacuum.
In this case, the organic vapor deposited layer 4 becomes liquid, increasing the adhesion between the surface of the rotary can 12 and the substrate 1, and greatly improving thermal conductivity. Along with this, a mechanism such as reacting with the metal thin film magnetic recording layer 3 and firmly adhering it is included, and a magnetic recording medium with excellent durability and C/N can be obtained. Further, the inside of the vacuum layer 8 can be configured such that a gas such as oxygen is forcibly introduced into all or part of the vacuum chamber from the outside as necessary. FIG. 2 is a cross-sectional view of a magnetic recording medium in which nonmagnetic layers or soft magnetic layers 6 and 7 are formed on a polymer substrate. When manufacturing such a magnetic recording medium, the manufacturing apparatus shown in FIG. In this case, for example, a sputter source is disposed, for example, along the cylindrical rotating cans 11, 12 prior to the formation of the metal thin film magnetic recording layers 2, 3. Note that the nonmagnetic thin film and the soft magnetic thin film may be formed by selecting one from those used for forming the metal thin film magnetic recording layer. The magnetic recording medium produced in this manner and a conventional general magnetic recording medium were compared as follows. Experimental example 1 Polyethylene terephthalate (average roughness 50Å)
Diameter 50cm with 10.5μm arranged at a center distance of 5/cm
Co80%Ni20 in an oxygen partial pressure of 5 x 10 ^-5 Torr at a minimum angle of incidence of 43° along the cylindrical rotating cans 11, 12 of
% alloy on 0.13 μm electron beam evaporation, respectively.
Octyl behenate was organically deposited to approximately 50 Å. The closest distance between the evaporation source and the part receiving evaporation on the rotating can was fixed at 25 cm. As [Comparative Example 1], the same Co--Ni was vapor-deposited on both sides, and each side was coated in a separate process to a calculated thickness of 50 Å by dissolving it in a solvent. The solvent used was n-hexane. As another [Comparative Example 2], Co--Ni was deposited and then octyl behenate was deposited, then the product was turned over and the same deposition was performed, and the same was evaluated. Each was cut into 8mm width and the durability was compared and the results are as shown in the following table. The tape length is 100m and the cylinder diameter is 40mm.
We repeatedly drove the deck using an improved running system of the VHS deck and observed changes in characteristics. The tape feed speed was 14.3 mm/sec, the head was a ferrite head, and the relative speed was 3.75 m/sec.
C/N was compared relatively with C=4.5MHz and N=4MHz. Dropout was counted and compared at 15μsec and -16dB.

[Table] By the way, the characteristics of the conventional most common method of vapor deposition on only one side, a back coat layer on the back side, and heat treatment for flattening are 30% at 25°C and 60% RH.
C/N decreases by 3.5dB at 30℃90%RH.
The C/N decreased by 3 dB in 12 passes. These C/N
The main cause of the decrease was a worsening of head touch due to changes in cupping. In addition, those having organic vapor-deposited layers on both sides had better still frame characteristics than conventional products, and had good practical durability. Initially, there was no significant difference in the comparative example, which was deposited in separate processes, but the fact that the magnetic recording layer and the organic deposited layer were formed continuously in the same vacuum layer by the manufacturing method of the present invention, and that both sides had the same structure The effect of continuous formation in a vacuum chamber can be considered to be reflected in the durability of the organic vapor deposited layer. Experimental example 2 On a polyamide substrate (average roughness 80 Å) 8.5 μm
Using a target of 81% Co and 19% Cr, a perpendicularly magnetized film of 0.2 μm was formed on each side by high-frequency sputtering, and a layer of stearic acid amide was added to approximately 40 Å.
A medium was obtained by organic vapor deposition. In this case, instead of the electron beam evaporation source shown in FIG.
A cathode with a longitudinal width of 6 inches is attached to the can 11,
Those placed 12 to 6 cm apart were used. In addition, the sputtering conditions are Ar partial pressure 3×
Organic deposition was performed in a vacuum of 2×10 ⁻⁴ Torr with a high frequency (13.56 MHz, 650 W) glow discharge at ^{10 −4} Torr. As with [Experimental Example 1], there was no change in the characteristics of this medium, but in a comparative example of the same type as [Experimental Example 1], the C/N deterioration was 60% at 25°C with the medium using the coating method.
After RH300 pass, after 30℃90%RH300 pass, respectively
It was extremely bad at 6.2dB and 9dB. [Experimental Example 1] and [Experimental Example 2] both have excellent corrosion resistance compared to the comparative example, and at 60°C 90%
Looking at the rate of change in Bs (saturation magnetic flux density) after being left at RH for one month, the change was 2 to 3%, whereas in the comparative example using the organic coating method, Bs decreased by 30% to 36%. The device formed in this manner differs from conventional devices and exhibits distinctive behavior in the following points. One of these is that even if the polymer substrate is repeatedly subjected to tensile stress by the running system, the envelope caused by the change in the cutting rate observed in conventional media with a bimetallic structure is caused by the fact that the polymer substrate is sandwiched by a thin metal film layer. The point is that there is no phenomenon where the condition gets worse. Second, since the thickness is extremely uniform on both sides, if the shape of the substrate is controlled, there is no shape transfer caused by conventional back coat layers, and excellent C/N can be achieved at short wavelengths. Note that if the cylindrical rotary cans 11, 12 and the vapor source are arranged symmetrically, it is possible to reliably obtain a metal thin film magnetic recording layer with the same thickness and the same physical properties. It is also possible to configure one of the layers to be a perpendicularly magnetized film. Effects of the Invention As explained above, according to the method of manufacturing a magnetic recording medium of the present invention, a magnetic recording medium that has excellent practical durability and can be accessed from both sides can be produced without the need for equipment such as a coating machine or a heat treatment machine. Can be manufactured using polluting equipment. Further, according to the manufacturing method of the present invention, it is possible to mass-produce metal thin film type magnetic recording media of stable quality and excellent practical durability. Furthermore, when a metal thin film magnetic recording layer is formed in a vacuum on the opposite side of the surface on which the organic material is continuously deposited, the organic material deposited layer becomes liquid and the adhesion between the second rotary can surface and the strip-shaped substrate deteriorates. Thermal conductivity is greatly improved. In addition, a magnetic recording medium with excellent durability and C/N can be obtained, which includes a mechanism such as reacting with the metal thin film magnetic recording layer and firmly adhering to it.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional configuration diagrams of magnetic recording media manufactured by the manufacturing method of the present invention, and FIG. 3 is a configuration diagram of an embodiment of a manufacturing apparatus that implements the manufacturing method of the present invention. be. 1... Polymer substrate, 2, 3... Metal thin film magnetic recording layer, 4, 5... Organic substance vapor deposition layer, 8... Vacuum layer,
9, 10... Exhaust system, 11, 12... Cylindrical rotating can [first and second cooling/transfer means], 13,
14, 15... Evaporation source container, 16... Delivery shaft, 17... Winding shaft, 19... Steam flow, 20...
...Ferromagnetic metal material, 23,24...Organic material.

Claims (1)

[Claims] 1 First and second for cooling and transporting the strip-shaped substrate
The cylindrical rotating cans are arranged with the winding sides facing each other, and an evaporation source for forming the metal thin film magnetic recording layer is arranged so that the vapor flow is directed toward the winding sides of the first and second rotating cans. The strip-shaped substrate is moved from the first rotation can to the second rotation can, and an organic substance evaporation source is disposed near the delivery side of the first and second rotation can, and the substrate is moved from the first rotation can to the second rotation can. 1. A method for manufacturing a magnetic recording medium, comprising laminating a metal thin film magnetic recording layer and an organic vapor deposited layer on both sides of the magnetic recording medium.