JPS62165730A - Manufacture of magnetic and recording medium - Google Patents

Abstract

PURPOSE:To eliminate cupping uniformly by holding a medium raw material in a low oxygen density atmosphere after forming of magnetic layer and applying heat treatment thereafter so as to reduce eracking at the heat treatment. CONSTITUTION:A plastic support film 3 payed off a pay-off roll 2 in the inside of a vacuum tank 1 is run along the circumference of a cylindrical rotary drum 4 and wound on a winding roll 5. On the other hand, a magnetic film 8 heated and vapor-deposited by a crucible 6 is vapor-deposited selectively on the film 3 passing by the rotary drum 4 by a shutter 7 and a vapor-deposition film 10 formed with a magnetic layer made of the metallic magnetic thin film is wound on the winding roll 5. The vapor-deposition film is kept as it is in the same vacuum tank 1 and left under a low oxygen density atmosphere. Before the heat treatment is applied, the film is taken out in air out of the atmosphere, the winding roll 5 is used as the supply roll and the heat treatment is applied by contacting and running the vapor-deposition film onto the heat drum 16 with a built-in heater between the winding roll 2 and the winding roll 5.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method of manufacturing a magnetic recording medium, such as a magnetic tape.

BACKGROUND OF THE INVENTION In the production of magnetic tapes, particularly vapor-deposited tapes, a magnetic material is vapor-deposited on one side of a substrate film, which often causes a non-uniform deformation of the film, called cupping.

When a cupped magnetic tape is used as a video tape, it may lack stability when running on a video deck, or may unwind when wound onto a reel. These tend to cause so-called edge folding, in which the edges of the tape break, and also cause problems in recording and reproducing video images.

Not only that, when tape curling occurs, the entire surface of the tape does not come into good contact with the head, so the output from areas with poor contact, such as when switching between heads, will be lower than the output from areas with good contact between the tape and head. The ratio decreases, the envelope shape deteriorates, and other electromagnetic conversion characteristics such as S/N deteriorate.

The above-mentioned adverse effects also occur when the tape becomes wavy or wrinkled, and if these are severe enough, the tape may not be usable at all. Furthermore, if a crack occurs, electromagnetic conversion characteristics such as S/N will deteriorate (and in severe cases, it may be detected as a large dropout).

In order to prevent cupping, heat treatment has been conventionally carried out by running the film in contact with a heat roll heated to a predetermined temperature. For example, JP-A-60-111345
Publication No. G describes a method in which a heating roll is disposed in front of a take-up roll in a vacuum evaporation apparatus for forming a magnetic thin film, and heat treatment is performed immediately after evaporation. But with this method,
Since heat treatment is performed immediately after vapor deposition in a vacuum chamber, it is difficult to perform appropriate heat treatment for each sample, and the speed of vapor deposition is limited because treatment with hot rolls begins immediately after vapor deposition. There are many problems, such as difficulty in dealing with problems when the film transport is disturbed.

Therefore, it is advantageous to perform the above heat treatment separately from the vapor deposition process, but in the conventional heat treatment, the film wound into a roll is taken out from the vapor deposition equipment into the atmosphere, held, and then Heat treatment is performed using a hot roll. However, in this case, the magnetic layer, especially near the interface with the base, begins to oxidize after several hours due to air entering from the end surface of the roll-shaped film that has been taken out of the vapor deposition apparatus and held in the atmosphere. This oxidized portion causes cracks during heat treatment. Furthermore, since this oxidation progresses from the end face of the base toward the center of the film, when heat treatment is performed, unevenness occurs between oxidized and unoxidized parts within the film. The forces and knocking in these respective parts are greatly different, which causes problems such as hindrance to conveyance and inability to uniformly remove the forces and knocking.

C.8 Purpose of the Invention The purpose of the present invention is to uniformly remove cupping in the width direction and longitudinal direction of a support, especially a film, and to remove cracks that occur in a magnetic layer during heat treatment to remove cupping. The purpose is to prevent wrinkles from entering the body.

23 Structure of the Invention That is, in the present invention, a magnetic recording medium material is created by forming a magnetic layer on a support, and then the magnetic recording medium material is placed in a low oxygen concentration atmosphere in a process step different from the formation of the magnetic layer. The present invention relates to a method of manufacturing a magnetic recording medium, in which the magnetic recording medium material is held in the magnetic recording medium and then heat-treated.

In the method of the present invention, a support with a magnetic layer (for example, a roll-shaped vapor deposited film) taken out from a magnetic layer forming apparatus such as a vacuum evaporation apparatus or a sputtering apparatus is heated to an oxygen partial pressure of 10 Torr.
Thereafter, it is preferably maintained in an atmosphere of ITo'rr or less, and immediately before heat treatment, it is taken out from the atmosphere into the atmosphere, and then a predetermined heat treatment is performed.

However, in the present invention, the above-mentioned atmosphere with an oxygen partial pressure of 10 Torr or less can be obtained by keeping it inside a vacuum evaporation apparatus or the like, or by putting it in a separate vacuum system. It may be kept in a sealed box purged with an inert gas. The oxygen concentration at this time should be as low as possible, but in practice it should be 10 Torr or less, preferably I
There is no problem if it is less than Torr.

Moreover, the above-mentioned "immediately before heat treatment" refers to a range from several hours to within one day, and when this is exceeded, the effect becomes weaker.

The heat treatment method is not particularly limited and may be any method that can apply heat uniformly, such as cupping the film.

E, Example Examples of the present invention will be described in detail below.

First, in the vacuum deposition apparatus shown in FIG. 1, a plastic support film 3 unwound from an unwinding roll 2 inside a vacuum chamber 1 runs along the circumference of a cylindrical rotating drum 4. Then, it is wound up on a winding roll 5. On the other hand, rotating drum 4
The magnetic metal 8 heated and evaporated from the crucible 6 is selectively deposited onto the film 3 by the shutter 7, and the deposited film 10 on which the magnetic layer made of the metal magnetic thin film is formed is transferred to the take-up roll. 5.

In this vapor deposition, for example, Go-N
The i-magnetic film was obliquely deposited to a thickness of 0.15 μm. At this time, as the evaporation source 8, Co: 80% by weight, Ni
:20% by weight was used, and reactive vapor deposition was performed while introducing 02 gas during vapor deposition.

The vapor-deposited film thus produced was kept as it was in the same vacuum chamber 1, and left to stand while being maintained in vacuum at a partial pressure of 10' Torr or less. Three hours before the heat treatment, the film was taken out from the vacuum chamber 1 and heat treated using an apparatus as shown in FIG. This device uses the roll 5 on which the vapor-deposited film was wound up in the process shown in FIG. 1 as a supply roll,
A heating drum 16 with a built-in heater is connected between the winding roll 22 and the winding roll 22.
The vapor-deposited film 10 is made to run in contact with the film (or a heated roll) and heat-treated.

First, the film 10 is transferred to the heat drum 16 via the guide roller 12, dancer roller 13, and guide rollers 14 and 15.
The nip roller 17 is applied to the cooling drum 18, and the guide roller 19 and the dancer roller 2 are brought into contact with the cooling drum 18.
0 and guide rollers 21.

At this time, the film 10 is moved by the dancer roller 13.20.
The tension of the drum 16 can be adjusted, and its surface temperature can be adjusted by, for example, steam supplied to the thermal drum 16. Further, the time period during which the film 10 is in contact with the thermal drum 16 can be adjusted by adjusting the winding speed of the winding roll.

During this heat treatment, the heating drum 1 with a surface temperature of 125°C
In step 6, heat treatment was performed while the film 10 was brought into contact and conveyed for 1 second at a tension of 600 g/dragon 2.

Sixteen tapes each having a width of 3n+ were slit from the thus heat-treated vapor-deposited film to produce each magnetic tape.

These tapes were designated as blocks 1 to 16 in order from the edge of the film.

Regarding these tapes Nos. 1 to 11h16, the transportability of the film during heat treatment, the presence or absence of cracks in the magnetic thin film, and the variation in the width direction of cuffing after heat treatment were examined. The results are shown in the table below (the same applies to the following examples).

The rolled film on which the magnetic thin film was deposited in the same manner as described in Main Example 1 of the fruit plate was taken out of the vacuum [1 (see Figure 1), placed in another vacuum chamber, and vacuumed to a partial pressure of 10''2 Torr. This vacuum was maintained for one week.Then, 5 hours before heat treatment, it was taken out from the vacuum chamber, heat treated in the same manner as described in Example 1, and slit into 16 magnetic tapes.

・ 3.4.5.6 and 1.2 The roll-shaped film on which the magnetic thin film was deposited in the same manner as described in Example 1 was once taken out of the vacuum chamber, placed in a sealed box where the inside could be replaced with gas, and heated to 0.2 partial pressure. is 10Torr (Example 3), 5Torr (Example 4), 1Torr (
Example 5), 0.5 Torr (Example 6), 15
The inside of the box was filled with N2 at Torr (Comparative Example 1) and 50 Torr (Comparative Example 2). After being left in this state for 2 weeks, it was taken out 3 hours before heat treatment, heat treated in the same manner as described in Example 1, and slit into 16 magnetic tapes.

・117.8.9 and 13 A roll-shaped film with a magnetic thin film deposited in the same manner as described in Example 1 was heated to a partial pressure of 10' Torr in the same vacuum chamber.
Keep under vacuum for 2 weeks and 5 hours before heat treatment (
Example 7), 10 hours before (Example 8), 24 hours before (Example 9), 48 hours before (Comparative Example 3), and Example 1
It was heat treated in the same manner as described above and slit into 16 magnetic tapes.

The film on which the magnetic thin film was deposited in the same manner as described in Pulling Example 1 was taken out of the vacuum chamber and left in the atmosphere for two weeks.
It was heat treated in the same manner as described in Example 1 and slit into 16 magnetic tapes.

(The following is a margin, continued on the next page.) From the above results, based on the present invention, the 02 partial pressure is
By keeping the temperature below QTorr and maintaining this temperature for up to one day before heat treatment, it is possible to improve transportability, reduce cupping, and prevent cracks.

The embodiments described above can be further modified based on the technical idea of the present invention.

For example, the material and shape of the support, the composition of the magnetic thin film, etc. may be changed in various ways. Further, the magnetic thin film can also be formed by a sputtering method or the like. As a heat treatment device, for example, it is possible to use a device that combines two or more thermal drums, or the drum surface is made of ceramics such as alumina, silicon, Teflon, etc., and any type of heat treatment device can be used as long as the above conditions are met. A combination is also possible. Further, the heating member may be other than the above-mentioned heating roll or heating drum, for example, a heating plate.

As described above, the present invention maintains the medium material in a low oxygen concentration atmosphere after forming the magnetic layer and then heat-treats it, thereby eliminating oxidation of the magnetic layer and preventing the occurrence of cracks during heat treatment. etc., and cupping can also be uniformly removed by heat treatment.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of a vacuum evaporation apparatus, and FIG. 2 is a schematic diagram of a heat treatment apparatus. In addition, in the symbols shown in the drawings, 3... Support film 5... Winding roll (roll-shaped film)
8... Evaporation source (evaporation metal) 16...
...Heat drum 18...Cooling drum 22...It is a roll.

Claims (1)

[Claims] 1. Create a magnetic recording medium material by forming a magnetic layer on a support, then hold the magnetic recording medium material in a low oxygen concentration atmosphere in a process step separate from the magnetic layer formation, and then A method for manufacturing a magnetic recording medium that heat-treats a recording medium material.