JPH0636280A - Manufacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To ease a residual internal stress by a method wherein a magnetic layer is formed on a support to produce a raw strip, both sides of a magnetic recording medium are heated by hot air and the medium is made to run in contact with a curl correction roll. CONSTITUTION:A magnetic layer is formed on a support made of a resin film or the like and wound in a roll to produce a raw strip 2 of a magnetic recording medium. The raw strip 2 delivered from an unwinding roll 1 is introduced into a thermal treatment device 5, passes through a curl correction roll 3 arranged in the device 5 to correct curling and is wound with a winding roll 4. The raw strip thus wound with the roll 4 is cut in an arbitrary shape such as card to obtain a flat magnetic recording medium. While the raw strip 2 runs in the device 5, it is heated from both the surface and rear sides thereof and passes being wound on the roll 3 simultaneously. Thus, the medium is subjected to an intense refining action and the residual internal stress generated in the support and a magnetic layer is removed thereby enabling the correction of curling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of magnetic recording media, and more particularly to a method for modifying curls such as magnetic tape and prepaid card backed by a plastic film.

[0002]

2. Description of the Related Art In a magnetic recording medium, a coating liquid for a magnetic layer prepared by dispersing ferromagnetic fine particles in a binder dissolved in a solvent is applied on the surface of a flexible non-magnetic support such as a polyester film. In addition to the coating type magnetic recording medium prepared by drying and solidifying, there is a non-coating type magnetic recording medium in which a magnetic layer is formed on the surface of the support by a method such as ion plating, sputtering or vacuum deposition. In the coating type magnetic recording medium, a urethane resin which reacts with an isocyanate group, for example, is generally used as a binder for maintaining the coating strength. Therefore, in order to prevent the occurrence of blocking after drying and solidification and to effectively promote curing, curing is performed at a constant temperature (about 40 ° C to 50 ° C) for a certain period (about 7 to 20 days) in a wound state. -I was doing. However,
Due to the thermal energy during this curing treatment, residual internal stress is generated in the magnetic layer and the support, so-called curl curl.
There was a problem that the problem occurs. Further, since the non-coating type magnetic recording medium is usually a method in which a ferromagnetic material is vacuum-deposited on the surface of a support by a cooling drum or the like, the ferromagnetic metal thin film layer formed on the surface of the support is not deposited during vacuum deposition. Residual internal stress is generated by the radiant heat of high-melting-point molten metal and the energy of evaporated metal particles, and the residual metal is applied to the ferromagnetic metal thin film layer side.
There was a problem that Therefore, conventionally, for the purpose of removing residual internal stress and reducing curl, for example, after forming a ferromagnetic metal thin film layer as in Japanese Patent Publication No. 1-35074, the surface of the ferromagnetic metal thin film layer is heated and heated. It has been proposed that the surface of the ferromagnetic metal thin film layer be blown with hot air, as in JP-A-62-60127. Further, JP-A-4-79023 proposes that one of the surface of the support or the surface of the ferromagnetic metal thin film layer is brought into contact with a heating roll, and at the same time hot air is blown to the other.

[0003]

However, with these methods, the residual internal stress of the ferromagnetic metal thin film layer is not sufficiently removed, and the curl of the non-coated magnetic recording medium can be sufficiently corrected. There wasn't. Further, in the case of a coating type magnetic recording medium having a thick support such as a prepaid card, it is difficult to correct the curls in the above-mentioned prior art. Curing was performed to prevent curling. In such a method, it is necessary to cut according to the size of the printing to be performed in the subsequent process, and therefore there is a problem that there is a great deal of waste in product management. It is an object of the present invention to provide a method of manufacturing a magnetic recording medium that can obtain a flat magnetic recording medium without curling.

[0004]

The present invention has been made as a result of various studies in view of the present situation. A magnetic layer is formed on a support to prepare a raw fabric, and the raw fabric is used as the support. The method for producing a magnetic recording medium is characterized in that one of the back surface of the magnetic recording medium and the surface of the magnetic layer is wound around a curl correcting roll and run in a hot atmosphere.

The method of manufacturing the magnetic recording medium according to the present invention will be described below in the order of steps. First, in order to manufacture a magnetic recording medium, a magnetic layer is formed on a support made of a plastic film or the like and wound into a roll to prepare a raw material of the magnetic recording medium. As the support constituting the present invention,
Paper, polyester film, polystyrene film, nylon film, polyvinyl fluoride film, polycarbonate film, polyimide film, polyamide film, or other plastic film or composite material sheet generally used for magnetic recording media is used. The magnetic layer formed on the support includes a magnetic layer for a non-coating type magnetic recording medium and a magnetic layer for a coating type magnetic recording medium, and a strong magnetic layer forming the magnetic layer of the non-coating type magnetic recording medium. Examples of magnetic materials include simple metals such as cobalt, nickel and iron, alloys or oxides of these, and Co-P,
Co-Ni-P or the like is used, and the magnetic layer is formed by vacuum deposition, ion plating, sputtering,
It is formed by means such as plating. As the ferromagnetic material forming a magnetic layer of a coating type magnetic recording medium, γFe ₂ O _3, Co-coated γFe ₂ O _3, BaO · 6F
e ₂ O ₃ or the like is used, and in the magnetic layer, a magnetic material and a surfactant are mixed with an appropriate binder, and the mixture is uniformly dispersed by a disperser such as a sand mill to prepare a coating for the magnetic layer. The reverse roll method, the doctor blade method or the like is used for coating and forming on the support.

Next, the process of removing the curl from the original roll of the magnetic recording medium wound in a roll will be described with reference to FIG. FIG. 1 is a schematic view of a curl correction device used in the method of manufacturing a magnetic recording medium of the present invention.
The raw material 2 of the magnetic recording medium sent from the unwinding roll 1 is introduced into the heat treatment device 5 by this device. The curl correction roll 3 disposed in the heat treatment device 5
The curl is corrected by passing through the winding roll 4 and is wound around the winding roll 4. The raw material of the magnetic recording medium wound on the winding roll is cut into an arbitrary shape such as a card shape to obtain a flat magnetic recording medium. In this way, the raw material 2 of the magnetic recording medium is heated from both the front and back sides while traveling in the heat treatment device 5, and at the same time, the raw material 2 of the magnetic recording medium is wound around the curl correction roll 3 and is squeezed, so that the magnetic recording is performed. The residual internal stress generated in the support and the magnetic layer forming the original fabric 2 of the medium is effectively removed, and the curl can be corrected. The surface of the original fabric 2 of the magnetic recording medium that comes into contact with the curl correction roll 3 may be the surface of the support or the surface of the magnetic layer.
However, in order to effectively correct the curl, it is preferable that the surface opposite to the original curved surface of the magnetic recording medium is brought into contact with the curl correcting roll and wound.

Here, the heat treatment device 5 is provided with a hot air supply hole 6 in the lower part and a hot air discharge hole 7 in the upper part so that the temperature can be adjusted. The hot air temperature of the heat treatment device is 80
It is preferable that the temperature is up to 130 ° C. and the wind speed is within the range of 1 to 30 m / s because the curl can be effectively corrected. Further, referring to the enlarged view of the curl correcting roll 3 in FIG. 2, it is preferable that the contact angle θ of the original 2 of the magnetic recording medium wound around the curl correcting roll 3 is variable. Because the curl of the original fabric 2 of the magnetic recording medium has different curl strength depending on the material and thickness of the support or the magnetic layer, the curl correction strength can be changed by making the contact angle θ variable. This is because the curl can be appropriately adjusted without excessively adjusting the curl. Specifically, in FIG. 1, there is a method in which the curl correction roll 3 can be moved up and down to make the contact angle θ variable. Further, as shown in FIG. 3, a first guide roll 8 is provided in front of the curl correction roll 3, and a second guide roll 9 is provided after the curl correction roll 3,
The curl correction roll 3 and the second guide roll 9 are made to contact the original fabric 2 of the magnetic recording medium in this order, and the first guide roll 8 and the second guide roll 9 are fixed.
The curl correction roll 3 can be moved vertically, or the curl correction roll 3 can be fixed and the first guide roll 8 and the second guide roll 9 can be moved vertically, or There is a method in which the contact angle θ can be made variable by adopting a structure in which the distance h between the first guide roll 8 and the second guide roll 9 can be arbitrarily set. In this case, the higher the height H of the curl correction roll, the larger the contact angle θ, and the residual internal stress generated in the support and the magnetic layer is easily removed. However, if the height H is too high, the apparatus itself becomes large. Therefore, the upper limit of the height H is preferably 200 mm. Here, the smaller the curl correction roll diameter, the stronger the bending force of the raw material of the magnetic recording medium. Therefore, both the hot air temperature and the wind speed may be appropriately selected and set according to the material and thickness of the support or the magnetic layer. An example of a curl correction device using the first guide roll and the second guide roll is specifically shown in FIG. In FIG.
The original 2 of the magnetic recording medium sent from the unwinding roll 1
Is introduced into the heat treatment apparatus 5 via the roll 10.
Then, the curl is corrected by traveling while contacting the curl correction roll 3 provided between the first guide roll 8 and the second guide roll 9 arranged in the heat treatment device 5. , The roll 11, and the roll 12 are wound around the winding roll 4. Further, FIG. 5 shows another curl correcting device in which the positions of the first guide roll 8, the curl correcting roll 3 and the second guide roll 9 in the curl correcting device of FIG. 4 are lying. is there.
Further, FIG. 6 shows still another curl correcting device,
The guide roll 8, the curl correction roll 3 and the second guide roll 9 are provided in plural.

[0008]

The curling of the magnetic recording medium is caused by the relaxation of the stress of the support and the magnetic layer by the heat received during or after the formation of the magnetic layer. Therefore, the curl generated by the stress relaxation can be corrected by relieving the stress by heat again. Therefore, in order to carry out curl correction effectively, both sides of the raw material of the magnetic recording medium are subjected to heat treatment, and at the stage of stress relaxation, the side for curl correction is wrapped around a curl correction roll to form an acute angle. It can be removed by "squeezing". Further, in the present invention, the layer formed on the support is a magnetic layer, but an electrosensitive recording layer, a photosensitive recording layer,
The same action and effect can be expected for those having layers such as a pressure-sensitive recording layer, a heat-sensitive recording layer, a photoconductor layer, and a wall covering layer.

[0009]

EXAMPLES The effects of the present invention will be illustrated below based on specific examples of the present invention. <Examples 1 and 2> A Co magnetic layer having a thickness of 2000 angstrom was formed on a polyester film having a thickness of 12 µm by a vacuum deposition method to prepare a roll-shaped raw material. Next, the original sheet of the magnetic recording medium on which this magnetic layer is formed is shown in FIG. 6 as a curl correction device (the diameter of the first and second guide rolls is 100 mm, the distance between the first and second guide rolls (h ) 80mm, curl correction roll diameter 2
0 mm, the surface of the raw material of the magnetic recording medium which is in contact with the guide correction roll is the support surface side), and each of them was treated at a traveling speed of 60 m / min under various conditions shown in Table 1. After that, this was cut into a predetermined size and subjected to curl measurement. Doctor polyester film of <Example 3 and 4> thickness 188 [mu] m - blur - the blade method, after forming a BaO · 6Fe ₂ O ₃ magnetic layer having a thickness of about 13 .mu.m, winding as the magnetic layer becomes outside Further, it was left in a curing chamber at a temperature of about 45 ° C. for 20 days to prepare a roll-shaped original fabric. Then
The raw material of this magnetic recording medium was processed in the same manner as in Examples 1 and 2. However, the traveling speed was set to 30 m / min, and the processing was performed under the various conditions shown in Table 1. After that, this was cut into a predetermined size and subjected to curl measurement. <Comparative Example 1> In Example 1, the original fabric is curl-corrected.
The process was performed in the same manner except that the step of wrapping around the reel was omitted. <Comparative Example 2> In Example 4, the original fabric is curl-corrected.
The process was performed in the same manner except that the step of wrapping around the reel was omitted. The height (H) of the curl correction roll is the distance between the bottom of the second guide roll and the top of the curl correction roll.

[0010]

[Table 1]

[0011]

[Table 2]

The curl amount is measured as shown in FIG. 7 by using a magnetic recording medium a obtained by forming a magnetic layer 22 on the surface of a support 21 with the magnetic layer 22 facing upward. The height g of the magnetic recording medium a in the assembled state was measured and measured. In this case, the convex state of the magnetic layer was a positive curl, and the concave state was a negative curl. The occurrence of wrinkles was visually observed on the magnetic recording media obtained in each of the examples and comparative examples, and the results are shown in Table 2. As is clear from Table 2, the magnetic recording medium obtained by the manufacturing method of the present invention is
It was confirmed that the curl could be effectively corrected without causing wrinkles.

[0013]

As described above, according to the present invention, both sides of the magnetic recording medium are heated with hot air and run while being in contact with the curl correcting roll, so that the residual internal stress of the support or the magnetic layer is reduced. It can be effectively relaxed, and a curl-free flat magnetic recording medium can be obtained. Further, in the present invention, by making the contact angle θ of the raw material of the magnetic recording medium wound around the curl correcting roll variable, optimal curl correction can be performed on the raw material of the magnetic recording medium having various curl states. You can

[Brief description of drawings]

FIG. 1 is a schematic diagram of a curl correction device showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a curl correction roll unit.

FIG. 3 is a diagram showing a positional relationship between a first guide roll, a curl correction roll, and a second guide roll.

FIG. 4 is a schematic view of a curl correction device showing another embodiment of the present invention.

FIG. 5 is a chart showing still another embodiment of the present invention.
It is a schematic diagram of a le correction device.

FIG. 6 is a chart showing still another embodiment of the present invention.
It is a schematic diagram of a le correction device.

FIG. 7 is a cross-sectional view of a magnetic recording medium for explaining a curl amount measuring method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Unrolling roll 2 Original roll of magnetic recording medium 3 Curl correction roll 4 Winding roll 5 Heat treatment device 6 Hot air supply hole 7 Hot air exhaust hole 8 First guide roll 9 Second guide roll

Claims (3)

[Claims] 1. A magnetic layer is formed on a support to prepare an original fabric, and one of the back surface of the original support and the surface of the magnetic layer is wound around a curl correction roll in a hot atmosphere. A method of manufacturing a magnetic recording medium, which is characterized in that it is made to run. 2. The method of manufacturing a magnetic recording medium according to claim 1, wherein the contact angle θ of the original film wound around the curl correction roll is variable. 3. The original roll is made to contact and travel in the order of a first guide roll, a curl correction roll and a second guide roll, and the curl correction roll and the first guide roll and the second guide roll are relatively moved. 3. The method of manufacturing a magnetic recording medium according to claim 2, wherein the contact angle .theta.