JPH0317826A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To form an extremely uniform lubricating layer in the atmosphere at ordinary temp. by heating a disk so as not to attain the temp. below the dew point in coating environment just prior to the application of a lubricant. CONSTITUTION:An underlying layer, a magnetic recording layer and a protective lubricating layer are formed by the conventional method on a substrate for the magnetic disk. The magnetic disk is heated by using an IR heater or the like just prior to the application of the lubricant at the time of forming the lubricating layer thereon. The heating temp. is set at the temp. at which the temp. of the disk does not fall below the dew point in the coating environment right after the evaporation of a volatile solvent, such as ethanol, of the lubricant. The coating thickness is specified to a 5 to 20Angstrom range. The condensation on the magnetic disk surface and the generation of water drops right after the application are prevented in this way and the extremely uniform lubricating film is formed in the atmosphere at ordinary temp.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a magnetic recording medium in which an extremely uniform lubricant layer is formed.

(Prior Art) A magnetic disk drive uses a floating head slider with an air bearing mechanism to fly a magnetic head over a disk medium rotating at high speed to a minute gap to perform recording and reproduction. Furthermore, a method (contact start-stop method) is adopted in which the magnetic head slides in contact with the magnetic recording medium when starting and stopping the rotation of the medium.

In this case, the magnetic recording medium itself has low lubricity, and the magnetic film of the magnetic head or magnetic disk wears out due to many contact sliding movements, and the wear spreads throughout the entire disk drive, causing a chain reaction of head crashes. I end up.

Therefore, in magnetic disk drives employing such a system, a lubricant is generally applied to the surface of the magnetic recording medium to improve sliding properties. However, if the lubricating film is made thicker on the entire or part of the surface of the magnetic recording medium, the sliding life of the magnetic disk medium will be somewhat longer, but an adhesion phenomenon will occur between the magnetic head and the magnetic recording medium. Moreover, if it is too thin, sufficient sliding properties cannot be obtained. Therefore, the lubricating layer formed on the surface of the recording medium must have an appropriate thickness and be extremely uniform. The lubricant is applied and removed by the subin coating method, spray coating method, or dip coating method. (Problems to be Solved by the Invention) However, even with conventional lubricant coatings, sliding properties cannot be sufficiently improved, and there is a problem in that magnetic recording media cause head crashes.

(Means for Solving the Problem) The present inventor has conducted various studies in order to overcome the above-mentioned drawbacks of the magnetic recording medium. (1) When the volatile solvent vaporizes, it rapidly removes a large amount of heat from the magnetic disk. Therefore, immediately after application, the temperature of the magnetic disk temporarily decreases and condensation occurs on the surface of the magnetic disk, and (2) if the water droplets generated on the surface of the magnetic disk are hydrophilic, the lubricant may When the lubricant is dissolved and evaporated again, the lubricant is concentrated in a specific area and remains, and if the lubricant is hydrophobic, the lubricant is pushed out around the water droplet, leaving the lubricant on the outer periphery of the water droplet. (3) Water droplets are generated on the magnetic disk surface during or immediately after the application of this I81/it agent. We have discovered that by avoiding this, it is possible to form a lubricant extremely uniformly on a magnetic disk, thereby producing a magnetic recording medium with excellent wear resistance.Based on this knowledge, we have developed the present invention. That is, the present invention, in manufacturing a magnetic recording medium,
Immediately after the solvent evaporates, a lubricant diluted with a volatile solvent is applied while the magnetic disk is heated to a temperature that does not lower the disk temperature below the dew point in the coating environment to form a lubricant layer. This article provides a method for manufacturing a magnetic recording medium with special features. As the magnetic disk substrate used in the present invention, conventionally used substrates can be used, such as glass, aluminum alloy, or aluminum. Furthermore, as the lubricant, conventionally used lubricants can be used, such as stearic acid monoglyceride.

In the present invention, after Ni--P plating is applied to the magnetic disk substrate, an underlayer, a magnetic recording layer and a protective lubricant layer are formed in this order by a conventional method, and then a lubricant is applied to form the lubricant layer. When applying this lubricant, treat the magnetic disk just before applying it. As a heating method, for example, using an infrared heater or the like, heating is performed in the atmosphere for an appropriate time until a desired temperature is reached. Preferred coating methods include spin coating, spray coating, and dip coating. Note that the lubricant used in the present invention is preferably diluted with a volatile solvent such as ethanol. Further, it is preferable that the lubricant be applied in the atmosphere at room temperature. Furthermore, the heating temperature of the magnetic disk should be such that the temperature of the magnetic disk does not fall below the dew point of the coating environment immediately after the solvent evaporates, and the heating temperature of the magnetic disk should be set so that the temperature of the magnetic disk does not drop below the dew point of the coating environment immediately after the solvent evaporates. It is preferable to heat the product to a level that does not exceed the lower of the boiling points.

The coating thickness of the lubricant is not particularly limited, but is preferably in the range of 5 to 20 people.

(Examples) The present invention will be described in more detail below based on Examples.

An aluminum substrate is used as the magnetic disk substrate, Ni-p plating is applied on this substrate, and Cr. A magnetic disk was fabricated by sequentially forming Co alloy and C by sputtering. Thereafter, a lubricant was applied, and the lubricant used was stearic acid monoglyceride, which was diluted to 1/8000 with ethanol. The magnetic disk is heated to about 70°C immediately before applying the 7ll/lI agent.

The heating method was to heat for 90 seconds in the air using an infrared heater (IKW). The application method is spin coating, and 3
A lubricant was dropped for 5 seconds at a rate of 0.5 cc/sec onto the inner circumferential portion of the disk that rotated horizontally at a rotation speed of 1,500 rpm, and the excess lubricant was then shaken off and dried.

The temperature of the magnetic disk immediately after coating was approximately 40°C. The surrounding environment during coating was 20°C, 80% RH, and atmospheric pressure. The magnetic recording medium prepared by this method is visually almost indistinguishable from the one before coating. In addition, the coefficient of dynamic friction is 0.15,
A contact start/stop test (CSS test) using a ferrite head was conducted for 20,000 cycles.

Comparative Example 1 A magnetic recording medium was produced in the same manner as in Example except that the magnetic disk was not heated before coating. A radial striped pattern was visually observed on the surface of this magnetic recording medium, and the coefficient of dynamic friction was 0.8 or more.

In the CSS test, a head crash occurred in less than 10,000 cycles.

Comparative Example 2 A magnetic recording medium was produced in the same manner as Comparative Example 1 except that the ambient environment was 20° C. and 60% RH. Clouding was visually observed on the surface of this magnetic recording medium. The coefficient of dynamic friction is 0
．． It was 4-0.6.

In the CSS test, a head crash occurred after 10,000 cycles or less.

(Effects of the Invention) According to the present invention, a magnetic recording medium having an extremely uniform lubricating layer formed on the surface and having excellent wear resistance can be stably manufactured in the atmosphere at room temperature.

Claims (1)

[Claims] When manufacturing magnetic recording media, a lubricant diluted with a volatile solvent is applied to the magnetic disk while it is heated to a heating temperature that does not cause the disk temperature to drop below the dew point in the coating environment immediately after the solvent evaporates. , a method for manufacturing a magnetic recording medium, comprising forming a lubricating layer.