JPS60133546A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent generation of crazing and wrinkling and to enable table removal of curling by coating the surface of a heat treating roll which removes curling of a vapor deposited film with a fluororesin. CONSTITUTION:A thin ferromagnetic metallic film is treated by vacuum deposition, etc. by which a magnetic layer is formed on a base body consisting of a flexible non-magnetic material and a magnetic recording medium (vapor deposited tape) 1 is obtd. A film consisting of a fluororesin such as polytetrafluoroethylene or the like is formed on the surface of a heat treating roll 3 which removes curling of the tape 1. The tape 1 is let off from an unwinding roll 2 and is heated by the roll 3, by which the curling is removed therefrom. Since the fluororesin film has an extremely low coefft. of dynamic friction, the generation of crazing and wrinkling in the tape 1 is prevented without sticking of the tape onto the roll surface and the stable removal of curling is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a magnetic recording medium for high-density recording having a magnetic layer of a ferromagnetic metal thin film on a substrate.

In recent years, with the increase in the density of magnetic recording, Fe has been deposited on flexible non-magnetic substrates, such as films of polyester, polyamide, polyimide, etc.

Magnetic recording media (hereinafter referred to as evaporated tapes) have been developed in which Co, Ni, or ferromagnetic metal thin films containing these as main components are formed as magnetic layers by processes such as vacuum evaporation, sputtering, ion blating, and electroplating. . .

However, although this vapor-deposited tape is suitable for high-density recording because its entire surface is made of a magnetic layer of a thin metal film, it has the disadvantage that it tends to curl because the thermal properties of the base and the magnetic layer are significantly different. Furthermore, this curl tends to cause trouble in the vapor-deposited tape running in contact with a magnetic head or the like.

Therefore, in order to remove curls from the vapor deposition tape, the vapor deposition tape 1 provided with a magnetic layer is passed from an unwinding roll 2 to a heat treatment roll 3 as shown in FIG. 1, where the curls of the vapor deposition tape are removed by heat. , and wind it up on a winding roll 4.

As the heat treatment roll, a metal roll whose surface is finished to 0.4SF4 degrees is usually used. On the other hand, since the magnetic layer of the vapor-deposited tape is required to have a maximum surface precision of about 0.005 μm, the surface of the substrate is also formed with the same surface precision. Therefore, when a vapor-deposited tape with such extremely high surface precision is heat-treated, the friction with the roll surface is large and it tends to come into close contact with the roll surface, which impairs running stability and makes it impossible to obtain a constant running speed. As a result, uniform decurling may not be achieved or the substrate may be partially thermally damaged. Furthermore, the unbalance between the uneven running speed and the tensile force caused by unstable running causes the substrate to stretch, causing cracks in the magnetic surface and wrinkles throughout the tape.

The purpose of this Q-4 is to provide a method for manufacturing a magnetic recording medium that eliminates the various drawbacks of the prior art described above and allows stable decurling without generating cracks or wrinkles.

That is, according to the present invention, in manufacturing a magnetic recording medium, a magnetic layer made of a ferromagnetic metal thin film is provided on a substrate made of a flexible non-magnetic material, and then curling is removed using a heat treatment roll. , the heat treatment roll is characterized in that its surface is coated with a fluororesin.

In the method of the present invention, first, Fe, C and
A ferromagnetic metal thin film made of O, Ni, or an alloy containing these as a main component is provided as a magnetic layer by a method such as electroplating, electroless plating, vacuum evaporation, ion blasting, or sputtering to form a vapor deposition tape. Next, the produced vapor-deposited tape is applied to an apparatus as shown in FIG. 1 to remove curls and form a magnetic recording medium.

In the present invention, a metal roll normally used for curl removal is used as the heat treatment roll, and the surface of the roll is coated with polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluorobroby-1-- Copolymer (FEP), hexafluoropropylene-perfluoroalkoxyethylene copolymer #cPFA)
, a fluororesin such as vinylidene fluoride is applied to form a film that is heat resistant and has low surface friction resistance.

Decurling of the vapor deposition tape is carried out at a temperature somewhat below the softening point of the substrate. For example, if the substrate is polyethylene terephthalate film, the heat treatment temperature is 120-150℃.
It is. Since the practical upper limit temperature of a fluororesin is about 200° C., a coating made of the resin will not be thermally damaged at the above-mentioned heat treatment temperature. In addition, since the fluororesin coating has an extremely small coefficient of dynamic friction with the surface of the vapor-deposited tape, the vapor-deposited tape that comes into contact with the roll surface can slide freely and maintain stable running without causing problems such as 411. . As a result, no cracks or wrinkles occur in the vapor-deposited tape.

Next, the present invention will be explained with reference to examples.

Example 1 A 0.2 μm thick Co-Ni alloy magnetic film was formed on a 2 μm thick polyethylene terephthalate film by vacuum evaporation, and this was designated as Sample 1@1.

This sample was run in contact with a stainless steel heat treatment roll (temperature 140°C) with a diameter of 200 m (temperature 140°C) as shown in Figure 1 at a running speed of 3 m10 to remove curls, and then cut into a predetermined width and coated with vapor-deposited tape ( Sample No. 2 (comparative example) was obtained.

Separately, a PTFE film was baked to a thickness of 0.5 μm on the surface of the same stainless steel heat treatment roll as above, and using this film, sample No. 1 was decurled in the same manner as described above. (Sample Ugly 3, Example) was obtained.

For the vapor deposited tapes of samples m2 and 3, the degree of curl removal and the occurrence of cracks and wrinkles were measured using the following method, and the results shown in Table 1 below were obtained.

Degree of Curl 2: The height from the lower end of the center of the vapor-deposited tape whose both ends are curled and curved upwards to the upper end of both ends is read with a microscope.

Occurrence of cracks and wrinkles: Predetermined length of vapor-deposited tape 1rrL
) The number of cracks and wrinkles that have occurred within the sample is read using a microscope.

As is clear from the results in Table 1, sample m3 obtained using the roll coated with fluororesin according to the present invention has better curl removal performance than sample Na2 (using a conventional heat-treated roll made of stainless steel). Although there is not much difference in the number of rolls, the occurrence of cracks and wrinkles is extremely reduced, and the effect of coating the roll surface with fluororesin becomes noticeable.

According to the present invention, by coating the surface of the heat treatment roll with a fluororesin, the vapor-deposited tape can stably run in contact with the roll surface without sticking to it during curl removal, and the occurrence of cracks and wrinkles can be completely prevented. To prevent. As a result, a magnetic recording medium with significantly improved recording and reproducing characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a heat treatment apparatus used for removing curls from a vapor deposition tape. 1... Vapor-deposited tape 2... Unwinding roll 3... Heat treatment roll 4... Winding roll Patent applicant Olympus Optical Industry Co., Ltd. Agent Patent attorney Takeshi Nara Figure 1

Claims (1)

[Claims] (1) In manufacturing a magnetic recording medium by providing a magnetic layer made of a ferromagnetic metal thin film on a substrate made of a flexible non-magnetic material and then removing curls with a heat treatment roll, the heat treatment roll is used as the heat treatment roll. A method for manufacturing a magnetic recording medium, characterized in that the surface thereof is coated with a fluororesin.