JPS6265237A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the adhesiveness of a lubricating agent layer and the durability of a recording medium by depositing the vapor of the lubricating agent having a polar group to a thin ferromagnetic metallic film layer which is held at negative potential in a vacuum deposition device. CONSTITUTION:A polyester film 3 on which the thin ferromagnetic metallic film layer 11 is formed is taken up from a stock roll 4 in a vacuum vessel 1 via guide rolls 5, 6 on a take-up roll 7. the rolls are maintained at the negative potential by the voltage impressed thereto and therefore, the thin film layer 11 is maintained at the negative potential as well. The inside of the vessel is evacuated by an evacuation system 10. The lubricating agent 9 having the polar group which is easily polarized to a positive side in an electric field is heated and evaporated so that said agent is deposited on the thin film layer 11. The lubricating agent 9 is thus securely deposited in the form of molecules on the surface of the thin film layer, by which the adhesiveness is additionally improved and the durability of the recording medium is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a magnetic recording medium having a ferromagnetic metal thin film layer as a magnetic recording layer, and more specifically, to a method for manufacturing a magnetic recording medium having excellent durability. Relating to a manufacturing method.

[Conventional technology]

A magnetic recording medium whose magnetic recording layer is a ferromagnetic metal thin film layer is
It is usually made by bonding metals or their alloys onto a base film by vacuum deposition, etc., and has characteristics suitable for high-density recording, but on the other hand, it has a high coefficient of friction with the magnetic head and is susceptible to wear and damage. It has the drawbacks of being easy to use and having poor durability.

For this reason, durability has traditionally been improved by depositing various lubricants on ferromagnetic metal thin film layers. For example, higher fatty acids such as stearic acid are vacuum deposited on ferromagnetic metal A lubricant layer with good lubricity is formed by depositing on a thin film layer. (Tokuko Showa 57-5
No. 6134) [Problems to be Solved by the Invention] However, in the method of depositing and forming a lubricant layer on a ferromagnetic metal thin film layer by such a conventional vacuum evaporation method, the lubricant layer on the ferromagnetic metal thin film layer is The adhesion of the layers is not sufficient,
As a result, the lubricant is easily lost due to sliding contact with the magnetic head, making it difficult to maintain a lubricating effect, and it is still not possible to sufficiently improve durability.

[Means for solving problems]

This invention was made as a result of various studies in view of the current situation, and consists of forming a ferromagnetic metal thin film layer made of metal or an alloy thereof on a substrate, and then forming a ferromagnetic metal thin film layer on this substrate. By applying a voltage to the layer in a vacuum atmosphere to make it have a negative potential, and applying a flow of illumination lubricant having a polar group at the molecular end to the ferromagnetic metal thin film layer at this negative potential, the electric field is applied. The lubricant, which has a polar group that is easily polarized to the + side, is well attracted to and firmly adhered to the ferromagnetic metal thin film layer at a negative potential, thereby improving the adhesion of the lubricant layer to the ferromagnetic metal thin film layer. sufficiently improved,
/121 The lubricant does not disappear in a short period of time, but its lubricating effect is maintained, and the durability is sufficiently improved.

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

FIG. 1 shows an example of a vacuum evaporation apparatus used in the present invention. This vacuum evaporation apparatus has a cylindrical can 2 disposed in the center of a vacuum chamber 1 to form a ferromagnetic metal thin film layer. The polyester film 3 is moved along the circumferential side of the cylindrical can 2 from a raw roll 4 via a guide roll 5, and is wound onto a take-up roll 7 via a guide roll 6. Here, a voltage is applied to the raw roll 4, the guide roll 5.6, and the take-up roll 7 to make them have a negative potential, and the ferromagnetic metal thin film layer on the surface of the polyester film 3 moving between these rolls has a negative potential. It runs at a potential. During this time, the cylindrical can 2
A lubricant powder 8 disposed at the bottom of the vacuum chamber 1 facing the
Then, the /121 lubricant 9 having a polar group is heated and evaporated, and its airflow is directed to the ferromagnetic metal thin film layer having a negative potential, thereby depositing the lubricant having a polar group. In addition, 1
0 is an exhaust system for reducing the pressure inside the vacuum chamber 1.

In this way, in the method using this vacuum evaporation apparatus, the peripheral surface of the cylindrical can 2 is guided by the original roll 4, the guide roll 5.6, and the take-up roll 7 to which a voltage has been applied to make the material negative potential. Since the vapor flow of the 4,lk agent, which has a polar group that is easily polarized to the + side in an electric field, is directed onto the surface of the ferromagnetic metal thin film layer at a negative potential on the polyester film 3 moving along the Even in the state of As a result, the adhesion of the lubricant layer to the ferromagnetic metal thin film layer is further improved, the lubricant effect is maintained, and the durability is sufficiently improved.

The lubricant to be deposited on such a negative potential ferromagnetic gold RI & thin film layer includes fatty acids, fatty acid metal salts, aliphatic compounds having a polar group at the molecular end such as fatty acid derivatives,
Alternatively, a fluorocarbon-based lubricant having a polar group at the end of the molecule is preferably used. In particular, when fatty acids, fatty acid metal salts, fatty acid derivatives, etc., straight-chain lubricants having 10 or more carbon atoms are used. Has good heat resistance and adsorption properties.
It is prized because the lubricant layer does not break due to the high temperature even if it generates heat due to sliding contact with the magnetic head for a long period of time, and it can exhibit an excellent lubrication effect for a long period of time.

Fatty acids used in this way include, for example:
Myristic acid, palmitic acid, oleic acid, stearic acid, behenic acid, etc. are preferably used, and the fatty acid metal salts include lithium salts, sodium salts,
Calcium salts, barium salts, cobalt salts, zinc salts and lead salts are preferably used. Furthermore, fatty acid derivatives include fatty acid esters such as stearate, butyl stearate, stearate monoglyceride, and oleic acid monoglyceride; fatty acid amides such as caproic acid amide, capric acid amide, behenic acid amide, stearic acid amide, and oleic acid amide. etc. are preferably used. As the fluorocarbon lubricant, perfluoropolyether having a carboxyl group or the like at the end of the molecule is preferably used.

i'IIfk is formed by vacuum depositing a lubricant having such a polar group on a ferromagnetic metal thin film layer at a negative potential.
The thickness of the lubricant layer is preferably within the range of 20 to 1000 lubricants; if the layer thickness is too thin, the lubricating effect of this lubricant layer will not be sufficiently exerted, and if it is too thick, the spacing loss will be too large. This adversely affects electromagnetic conversion characteristics.

In addition, the lubricant having a polar group at the molecular end is deposited by directing the vapor onto the ferromagnetic metal thin film layer at a negative potential by vacuum evaporation as described above or by ion blasting, sputtering, etc. In these cases, the same effect as in the case of vacuum evaporation described above can be obtained.

The material for forming the ferromagnetic gold gilt film layer is Co, Ni.
, metals such as Fe, alloys such as Go-Ni, Co-Cr, or oxides of these metals and alloys, Co-P, C
All ferromagnetic materials commonly used in vacuum deposition, such as o-N1-P and iron oxide magnetic materials such as r-Fe203 and Fe304, are preferably used, and the ferromagnetic metal thin film layer made of these ferromagnetic materials is The material is deposited on the substrate by means such as vacuum evaporation, ion blating, sputtering, and plating.

In addition, as magnetic recording media, polyester film,
There are various types of structures that come into sliding contact with the magnetic heel, such as magnetic tapes based on plastic films such as polyimide films, magnetic disks and magnetic drums based on disks and drums made of plastic films, aluminum plates, glass plates, etc. include.

〔Example〕

Next, embodiments of the invention will be described.

Examples 1 to 5 A polyester film with a thickness of 10 μm was loaded into a vacuum evaporation apparatus, and a cobalt-chromium alloy (weight ratio 87:13) was heated and evaporated under a vacuum of 5×10″5 Torr to form a thick layer on the polyester film. A ferromagnetic metal thin film layer made of 1,000 cobalt-chromium alloys was formed.
Using the vacuum evaporation apparatus shown in the figure, the polyester film 3 on which the ferromagnetic metal i-film layer is formed is moved from the raw roll 4 through the guide roll 5 along the circumferential side of the cylindrical can 2, and then the A voltage was applied to the material roll 4, the guide roll 5.6, and the take-up roll 7, which were set to be wound up on the take-up roll 7 via the roll 6, and their potentials were shown in Table 1 below. Lithium stearate 9 was heated and evaporated using a lubricant evaporation ring 8 disposed at the bottom of the vacuum chamber 1 to perform vacuum deposition, thereby forming a lubricant layer for 200 people. Thereafter, it is cut into a predetermined size, and a ferromagnetic metal film 1ii11 and a lubricant layer 1 are formed on the polyester film 3 as shown in FIG.
A magnetic tape A was prepared by sequentially laminating the magnetic tapes 2 and 3.

Example 6 Magnetic tape A was produced in the same manner as in Example 4 except that CgFssCOOH was used instead of lithium stearate in forming the lubricant layer in Example 4. The thickness of the lubricant layer at this time was 70 people.

Example 7 Magnetic tape A was produced in the same manner as in Example 4, except that stearamide was used instead of lithium stearate in forming the lubricant layer in Example 4. The thickness of the lubricant layer at this time was 150.

Comparative Example 1 In Example 1, the raw roll 4, guide rolls 5, 6
A magnetic tape was produced in the same manner as in Example 1, except that no voltage was applied to the take-up roll 7 and the potential was O. The thickness of the lubricant layer at this time was 200.

The durability of the magnetic tapes obtained in each example and comparative example was investigated by measuring still playback life.

Table 1 below shows the results.

Table 1 [Effects of the Invention] As is clear from the above table, the magnetic tapes obtained by the present invention (Examples 1 to 7) all had better still reproduction than the magnetic tape obtained in Comparative Example 1. It has a long lifespan, which shows that the manufacturing method of the present invention provides a magnetic recording medium with even greater durability.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a vacuum evaporation apparatus used in the manufacturing method of the present invention, and FIG. 2 is a partially enlarged cross-sectional view of a magnetic tape obtained by the present invention. 1... Vacuum chamber, 3... Polyester film (substrate), 4... Original fabric roll, 5.6... Guide roll,
7... Winding roll, 9... Lubricant, 11...
Ferromagnetic metal thin film layer, 12...Lubricant layer, A...Magnetic tape (magnetic recording medium) Patent applicant Hitachi Maxell Ltd. Figure 1 Figure 2-5 Holies T-Film

Claims (1)

[Claims] 1. A ferromagnetic metal thin film layer made of metal or an alloy thereof is formed on a substrate, and then a voltage is applied to the ferromagnetic metal thin film layer formed on this substrate in a vacuum atmosphere to make it have a negative potential. A method for manufacturing a magnetic recording medium, which comprises depositing vapor of a lubricant having a polar group at the molecular end on a ferromagnetic metal thin film layer brought to a negative potential to form a lubricant layer.