JPS62102426A - Method and device for manufacturing magnetic recording medium - Google Patents

Abstract

PURPOSE:To correct the disturbance of orientation and to improve high density recording by pulling in and out a base posted with a magnetic paint between N-S counter magnets in a vertical magnetic field orienting device right after bonding the magnetic point and right before the completion of coat drying. CONSTITUTION:A frame 10 and a magnet holder 11 are constructed of a permeable material, and act as a yoke. Accordingly, the N-S counter magnet 50 is enclosed with a yoke in its vicinity, and a diamagnetic field emitted from the magnet 50 is absorbed and attenuated, thereby increasing a vertical magnetic field. Moreover a base film 2 having an undrying coat 4 is hardly affected by the diamagnetic field when it goes in and out between the magnets 50, and magnetic grains in the coat 4 can be satisfactorily oriented in a vertical direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a magnetic recording medium suitable for high-density recording, and an apparatus used to carry out the method.

[Conventional technology]

Generally, a magnetic recording medium such as a magnetic tape is produced by rotating a reverse roll while running a base film 2 fed out from a feeding roll 1 at a constant speed, as shown in FIG.
Magnetic paint is applied with a coating machine 3 such as a gravure roll, and while the paint film 4 is in an undried state, it is guided to a magnetic field orientation device 5 to orient the axis of easy magnetization of the magnetic particles in the paint film 4 in a certain direction. After that, it is connected to the dryer 6 to be completely dried and cured.
After that, it is wound up on a winding roll 7.

In the magnetic field orientation bag W5, in recent years, the magnetic field orientation device 5 is used as a method for obtaining a magnetic recording medium suitable for high-density recording.
The base film 2, which is composed of 8 opposing magnets and has an undried coating film 4 between the N-3 opposing magnets, is introduced and taken out, and the coating film 4 is
The easy axis of magnetization of the magnetic particles therein is oriented in the vertical direction. However, in such an orientation method, since a demagnetizing field acts on the introduction and exit side of the base film 2 with respect to the central magnetic field of the N-8 opposing magnet, magnetic particles once vertically oriented by the central magnetic field or The orientation is disturbed by the influence of the demagnetizing field on the output side of the film 2, and as a result, the magnetic particles in the coating film 4 are not oriented perpendicularly well enough, and the magnetic properties cannot be sufficiently improved to achieve the recording density. The problem was that it was not possible to increase the density.

Therefore, as a method to overcome this problem, the present inventors installed a vertical magnetic field orientation device between the coating machine and the dryer, which is made by connecting at least both left and right sides of ll-3 opposing magnets with a yoke made of a magnetically permeable material. After applying magnetic paint on the head, the demagnetizing field of the N-5 opposing magnet is absorbed and attenuated by the yoke by introducing it between the N-3 opposing magnets of this vertical magnetic field orientation device. It has already been proposed to easily orient the easy axis of magnetization of magnetic particles in the perpendicular direction, increase the perpendicular magnetic field, and increase the recording density.

(Unexamined Japanese Patent Publication No. 59-13914.1) [Problems to be Solved by the Invention] However, a vertically oriented coating film in which the axis of easy magnetization of magnetic particles is oriented in the perpendicular direction is susceptible to the reaction generated in the coating itself. Due to the magnetic field, once the magnetic particles are oriented, their orientation is disturbed when they go out of the oriented magnetic field, so at least both left and right sides of the N-3 facing magnet are connected by a yoke made of a magnetically permeable material. Even with a method using a vertical magnetic field orientation device, this disturbance in orientation cannot be suppressed, and fully satisfactory results have not yet been obtained.

[Means for solving problems]

This invention was made as a result of intensive research to overcome this problem, and it is located immediately after the coating machine that applies the magnetic paint onto the base and immediately before the drying of the paint film is completed in the drying process. A vertical magnetic field orientation device comprising N-8 opposing magnets connected at least on both left and right sides by yokes made of a magnetically permeable material is installed, and the hair coated with the magnetic paint is moved immediately after the application of the magnetic paint. Immediately before the drying of the coated film is completed, the magnetism that has been oriented once in the vertical magnetic field orientation device immediately after the coating machine is introduced between the N-8 opposing magnets of the vertical magnetic field orientation device installed. Even if the particles move out of the alignment magnetic field and their orientation is disturbed, they are oriented again using a vertical magnetic field orientation device located just before the drying of the coating film is completed, and the disturbance in orientation is well corrected and the coating is completed. The vertical orientation of the magnetic particles is well maintained without disturbing until just before the drying of the film is completed, and high-density recording is sufficiently improved.

This invention will be explained below with reference to the drawings.

FIGS. 1 and 2 show an example of a vertical magnetic field orientation device according to the present invention. In the figure, 10 is a rectangular frame whose front and rear central parts are hollow, and N-3 opposing magnet 50
．． 50 are held in the central hollow part of the frame 10 by magnet holders 11 and 11 fixed to the top and bottom of the frame 10, respectively, so as to be vertically slidable. Here, the frame 10 and the magnet holder 11.11 are both made of magnetically permeable material and function as a yoke. Therefore, N-3 opposing magnet 50.
50 is surrounded by a yoke, and this surrounding yoke absorbs and attenuates the demagnetizing field emitted from the N-3 opposing magnet 50.5o, so that the vertical magnetic field can be increased and the base has the undried coating film 4. When the film 2 is introduced between the opposing magnets 50 and 50, it is hardly affected by the demagnetizing field, and therefore the magnetic particles in the coating film 4 are well oriented in the vertical direction.

Reference numeral 12 denotes a scale affixed to the front right side of the frame body 10, and reference numeral 13 denotes an adjustment scale which is fitted and supported by a support stand 14 installed on the upper end of the frame body 10, and whose lower half threaded portion is screwed onto the magnet holder 11. Similarly, the screw 15 is an adjustment screw that is fitted into and supported by a support stand 16 installed at the lower end of the frame 10, and whose lower half screw portion is screwed into the magnet holder 11. Through adjustment, the spacing between the opposing magnets 50, 50 is adjusted to match the graduations of the scale 12. These scales 12, adjustment screws 13.15 and supports 14.16
The yoke is also made entirely of magnetically permeable material and functions as a yoke.

Note that in the vertical magnetic field orientation device 5A shown in FIGS. 1 and 2, the entire periphery between the N-3 opposing magnets 50 and 50 is surrounded by a yoke, but it is not necessarily necessary to surround the entire periphery with a yoke. (At least, the left and right sides 17 and 18 of the N-3 opposing magnet should be connected with a magnetically permeable material that acts as a yoke so that the opposing magnet can slide up and down, and the same effect can be obtained in this case. The magnetically permeable material that functions as such a yoke can be arbitrarily selected, but generally a high magnetically permeable material such as iron or permalloy is preferably used.

FIG. 3 shows the magnetic field orientation device 5A of the present invention, in which the vertical magnetic field orientation device 5A shown in FIGS. This is a schematic diagram of a recording medium manufacturing apparatus. Magnetic paint is applied onto a base film 2 that is fed out from a feed roll 1 and runs at a constant speed using a coating machine 3 such as a reverse roll or a gravure roll. Immediately, the magnetic particles are guided between the N-3 opposing magnets 50 and 50 of the vertical magnetic field orientation device 5A+ disposed immediately after the coating machine 3, so that the easy axis of magnetization of the magnetic particles in the coating film 4 is oriented in the vertical direction. Then, the magnetic particles in the coating film 4 are introduced into the dryer 6, and immediately before the drying is completed, they are guided between the N-3 opposing magnets 50 and 50 of the vertical magnetic field orientation device 5A2 disposed in the dryer 6. The axis of easy magnetization is again oriented in the perpendicular direction, and after the orientation is completed, it is completely dried and cured, and then wound onto a winding roll 7. According to this method, the magnetic particles oriented in the vertical magnetic field orientation device 5A immediately after applying the magnetic paint on the base film 2 are drawn out from the vertical magnetic field orientation device 5A+, and then the magnetic particles are oriented in the coating film itself. The orientation of the magnetic particles is temporarily disturbed due to the generated demagnetizing field, but the magnetic particles are oriented again in the vertical magnetic field orientation device 5A2 immediately before drying is completed in the dryer 6, so the temporary disturbance of the orientation of the magnetic particles is prevented. A magnetic recording medium can be obtained in which the magnetic particles are well-corrected with almost no disturbance, the axes of easy magnetization of the magnetic particles are well oriented in the perpendicular direction, and high-density recording is sufficiently improved.

In addition, in FIG. 3, the vertical magnetic field orientation device 5A2 is disposed inside the dryer 6, but this vertical magnetic field orientation device 5A2 does not necessarily have to be disposed inside the dryer 6. If the dryer is comprised of a dryer, it may be placed at a position immediately before the last dryer and before drying is completed.

〔Example〕

Next, embodiments of the invention will be described.

Example 1 Plate-shaped barium ferrite magnetic powder 800 parts by weight (particle size 0.3 μm, coercive force 900 oersted, saturation magnetization 60 emu/g) Vinyl chloride-vinyl acetate-vinyl alcohol copolymer polyurethane elastomer 80 Trifunctional low molecular weight isocyanate 20 Compound cyclohexanone 750/l Toluene 750 This composition was mixed and dispersed in a ball mill for 72 hours to prepare a magnetic paint. This magnetic paint was applied to a coating thickness of 2 μm onto a 21 μm thick polyester base film 2 using a coating machine 3 using the magnetic recording medium manufacturing apparatus shown in FIG. It was introduced into the vertical magnetic field orientation device 5AI immediately after the machine tool 3, and oriented in the vertical direction using an orientation magnetic field of 3000 Gauss. Next, it is introduced into the dryer 6, further introduced into the vertical magnetic field orientation device 5A2 in the dryer 6, and oriented in the vertical direction with an orientation magnetic field of 3000 Gauss, and after completing drying in the dryer 6, a predetermined width is I cut it into pieces and made magnetic tape.

Example 2 In the composition of the magnetic paint in Example 1, α-Fe magnetic powder (
Example 1 except that the same amount of long axis diameter 0.3 μm, coercive force 1200 Oersted, and saturation magnetization 120 emu/g was used, and the alignment magnetic field of the vertical magnetic field alignment devices 5A+ and 5A2 was changed from 3000 Gauss to 4000 Gauss. I made magnetic tape in the same way.

Comparative Example 1 In Example 1, vertical magnetic field orientation devices 5A and 5A
A magnetic tape was produced in the same manner as in Example 1, except that the perpendicular magnetic field orientation treatment in Step 2 was omitted.

Comparative Example 2 A magnetic tape was produced in the same manner as in Example 1, except that the vertical magnetic field orientation process in the vertical magnetic field orientation device 5A2 was omitted.

Comparative Example 3 A magnetic tape was produced in the same manner as in Example 1, except that the vertical magnetic field orientation process in the vertical magnetic field orientation apparatus 5A was omitted.

Comparative Example 4 In Example 2, vertical magnetic field orientation devices 5A and 5A
A magnetic tape was produced in the same manner as in Example 2, except that the vertical magnetic field orientation treatment in Example 2 was omitted.

Comparative Example 5 A magnetic tape was produced in the same manner as in Example 2, except that the vertical magnetic field orientation process in the vertical magnetic field orientation device 5A2 was omitted.

The perpendicular coercive force, perpendicular squareness (Br/Bs), and perpendicular residual magnetic flux density of the magnetic tapes obtained in each example and comparative example were measured.

The table below shows the results.

Table [Effects of the Invention] As is clear from the above table, the magnetic tapes (Examples 1 and 2) obtained by the magnetic recording medium manufacturing apparatus and manufacturing method of the present invention are superior to those obtained in Comparative Examples 1 to 5. Compared to tape, the perpendicular coercive force, square shape, and residual magnetic flux density are all higher. Therefore, according to the magnetic recording medium manufacturing apparatus and manufacturing method of the present invention, the magnetic recording medium has excellent magnetic properties and is suitable for high-density recording. It can be seen that a magnetic recording medium can be obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a perpendicular magnetic field orientation apparatus used in manufacturing the magnetic recording medium of the present invention, FIG. 2 is an enlarged front view of the same,
FIG. 3 is an explanatory diagram showing an outline of the manufacturing process of the magnetic recording medium of the present invention, and FIG. 4 is an explanatory diagram showing an outline of the manufacturing process of a conventional magnetic recording medium. 2...Base film (base), 4...Coating III
, 50...N-3 opposing value stone, 5A, 5A1.5A2.
... Vertical magnetic field orientation device, 6... Dryer Fig. 1 5A Vertical magnetic field orientation device

Claims (1)

[Claims] 1. Magnetic paint is applied onto the base, and then, immediately after applying the magnetic paint and immediately before the drying of the coated film is completed, at least both left and right sides are coated with a magnetically permeable material. Method 2 for producing a magnetic recording medium, characterized in that the magnetic coating is introduced between N-S opposing magnets connected by a yoke, and the axis of easy magnetization of the magnetic particles in the coating is oriented in the perpendicular direction. Immediately after the coating machine that applies the coating film and immediately before the drying of the coating film is completed in the drying process, there is an N-
A vertical magnetic field orientation device comprising S facing magnets is installed,
A magnetic recording medium manufacturing apparatus characterized in that a base coated with magnetic paint is introduced between the N-S opposing magnets of both vertical magnetic field orientation devices.