JPS6390031A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To form uniform lubricating layers on magnetic layers by subjecting media coated with lubricative org. material layers which are liquid at a room temp. to a vacuum evacuation treatment in a 120 deg.C range from the room temp. CONSTITUTION:Magnetic disks 2 formed with the lubricative org. material layers which are liquid at the room temp. are mounted to a disk fixing jig 3 in a vacuum vessel 1. After the inside of the vacuum vessel 1 is evacuated to <=1X10<-3>torr by a vacuum pump, the temp. is changed from the room temp. to a 120 deg.C range by a heater 4, by which the vacuum evacuation treatment is executed. As a result, the contamination on the surfaces of the magnetic layers which retard the wet spreading of the lubricating agent is removed and the wet spreading of the lubricating agent is satisfactorily executed. The uniform lubricating layer is thus formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a magnetic recording medium, and particularly to a method of manufacturing a magnetic recording medium such as a magnetic disk, magnetic tape, magnetic card, or floppy disk.

[Conventional technology]

In general, a magnetic recording medium has a magnetic layer formed on various substrates, and the surface of the magnetic recording medium is rubbed by a magnetic head when a magnetic recording device is started, stopped, recorded, or reproduced. For this reason, a lubricating layer has been conventionally provided on the surface of the magnetic layer to prevent performance deterioration due to abrasion of the magnetic layer that occurs during friction.

These lubricating substances include silicone oil, higher fatty acids,
Fluorine oil etc. are used.

Generally, methods for applying the above-mentioned organic lubricating substance to the surface of the magnetic layer include preparing a solution in which the lubricating substance is dissolved in an organic solvent, and using the solution in a spin code method, dipping method, spray method, etc. It is used.

[Problem that the invention seeks to solve]

In the above lubricant layer application method, the lubricant layer on the magnetic layer is not uniformly applied, and there are some non-uniformities such as the presence of parts where the lubricant layer does not cover the magnetic layer, resulting in insufficient lubricant performance. The lubricant layer that can be drawn out is not obtained. It is also known that excessive application of a lubricant, in the case of a liquid lubricant, causes stickiness due to its surface tension, which adversely affects the running performance of the magnetic head.

The object of the present invention is to eliminate such disadvantages and provide a uniform and uniform lubricating layer.

[Means for solving problems]

The above purpose is to create a non-uniform lubricating layer made of an organic material that is liquid at room temperature and has a vapor pressure of less than I x 10"-3 torr at room temperature, applied by conventional spin-coding, dipping, spraying, etc. methods. Vacuum degree is IX 10-at
This is achieved by performing a vacuum evacuation process at a temperature in the range of room temperature to 120°C.

[Effect]

When a lubricant that is liquid at room temperature is applied using a spin cord method, dipping method, spray method, etc., the lubricant spreads over the magnetic layer to form a lubricant layer, but factors that inhibit wetting of the lubricant include: There is dirt on the surface of the magnetic layer. Dirt on the surface of the magnetic layer includes adsorption of water molecules and organic molecules in the atmosphere, which inhibits the spread of lubricant, but this dirt can be removed by evacuation or heating during evacuation. As a result, the lubricant spreads and eliminates the areas not covered by the lubricant layer, making it possible to obtain a uniform lubricant layer. Further, when the lubricant is returned to the atmosphere after the evacuation process, the lubricant is pushed into the gaps such as pores in the magnetic layer by atmospheric pressure, and the impregnation of the lubricant into the magnetic layer is promoted.

〔Example〕

Examples of the present invention will be shown below.

As magnetic recording media, epoxy resin, phenolic resin,
Magnetic powder (
After cleaning a 5-inch diameter coated magnetic disk manufactured by dispersing γ-Fe20a) with trichlorotrifluoroethane, a liquid lubricant layer shown in formulas 1 and 2 was sprayed on the surface of the magnetic layer of this magnetic disk. After forming by law,
A magnetic disk with improved uniformity of the lubricant layer was constructed using the vacuum evacuation processing device described below.

Formula I F (CF (CFJI)'-'C'FzO)nCF2
OF8 average molecular weight 4500 Formula 2 % Formula %) The lubricant film thickness is 10 m from the FT-I'R difference spectrum.
The average value of the m diameter was measured.

FIG. 1 shows a vacuum evacuation processing apparatus used for manufacturing the magnetic recording medium of the present invention. A magnetic disk 2 on which a liquid lubricant layer is formed in a vacuum container 1 can be placed on a magnetic disk fixture 3 and taken out. The inside of this vacuum container 1 can be maintained at an arbitrary degree of vacuum and temperature by a vacuum pump (not shown) and a heating device 4.

The nonuniformity of the lubricating layer was evaluated by the contact angle of n-hexadecane with the surface of the magnetic disk. The above contact angle depends on the change in the adhesion area of the lubricant layer to the magnetic layer, from the contact angle on the surface of the magnetic layer without a lubricant layer to the contact angle on the lubricant itself when the lubricant layer completely covers the surface of the magnetic layer. Change.

A spherical sliding test was conducted to evaluate the durability of the lubricating layer for improving its uniformity. The spherical sliding test was conducted using an α-alumina slider (curvature radius 30m) with a 20g load applied to the magnetic disk.
m) with a sliding speed of 10 m
/ s, and measure the number of times of sliding until scratches occur on the surface of the magnetic layer. This test is C8/S (contact start and stop co
ntact 5tartand 5top) Corresponds well to sliding tests.

Examples 1 to 4 A magnetic disk on which a lubricating layer of approximately 25 nm was formed by the above-mentioned spray method was placed at a vacuum degree of I x 10-3 torr.

Examples 1 to 4 show the results of the magnetic disk subjected to the vacuum evacuation treatment under the conditions of a temperature of 20°C and a processing time of 1 hr, and the results when the temperature was changed to 100°C under the above conditions, respectively.
as shown in Table 1.

Comparative Examples 1 to 5 The results for the magnetic layer surface before forming the lubricant layer are referred to as Comparative Example 1, and the results when the lubricant layer is applied thickly and the magnetic layer surface is completely covered are referred to as Comparative Examples 2 to 3. Comparative Example 4 shows the results obtained only by the spray method without performing the vacuum evacuation process.
-5 are shown in Table 1, respectively.

As shown in Table 1, the contact angle of the magnetic disk subjected to the vacuum evacuation treatment is significantly increased, and the uniformity of the lubricating layer is improved. Additionally, as the contact angle improves, the sliding strength also improves, and durability is also improved.

Table 1 [Effects of the Invention] As is clear from the above examples, according to the present invention, the uniformity of the lubricating layer can be improved and durability can be improved.

This effect can be achieved by using the dip method in addition to the above embodiments.

A similar effect is exhibited on coated magnetic disks with a lubricant layer formed by the spin code method and metal thin film magnetic recording media with a lubricant layer formed by the spray method, dip method, or spin code method.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an example of an apparatus used in the method of manufacturing a magnetic recording medium of the present invention. 1... Vacuum container, 2... Magnetic disk, 3... Fixture, 4... Heater.

Claims (1)

[Claims] 1. A method for manufacturing a magnetic recording medium, which comprises performing a vacuum evacuation treatment on a magnetic recording medium provided with a liquid lubricating organic layer at room temperature. 2. The vacuum degree of the above vacuum evacuation process is 1×10^-^3to
2. The method of manufacturing a magnetic recording medium according to claim 1, wherein the magnetic recording medium is less than or equal to rr. 3. The vapor pressure of the above organic layer at room temperature is 1×10^-^5
3. The method of manufacturing a magnetic recording medium according to claim 2, wherein the magnetic recording medium has a torr or less. 4. The method for manufacturing a magnetic recording medium according to claim 3, wherein the average deposited film thickness of the organic layer calculated from the average deposited weight and density is 5 to 50 nm.