JPS6154038A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To orient effectively magnetic powder in a longitudinal direction and to obtain a magnetic recording medium having an excellent electromagnetic conversion characteristic by coating a magnetic paint on a substrate film and passing the film through the inside of an orienting magnetic field while bringing a high permeability metallic material in proximity or contact with the undried magnetic coated film. CONSTITUTION:A metallic film 10 having high magnetic permeability is formed by a vapor deposition method, etc. on the surface of synthetic resin film 9 while the undried magnetic coated film 1 formed by coating the magnetic film on a substrate film 2 is run in the direction shown by an arrow A via a backing roll 3 to form a flexible sheet 8 subjected to a smoothing treatment. Such film 8 attached to a seat roll 11 is provided in such a manner that the film 9 side contacts with the film 1 and an orienting magnetic field is applied thereto from permanent magnets 41, 42. Solenoids may be used in place of the permanent magnets. The orienting magnetic fluxes are thus concentrated by the film 10 and the magnetic powder is longitudinally and satisfactorily oriented; at the same time, the surface is subjected to the smoothing treatment. The magnetic recording medium having the excellent electromagnetic conversion characteristic is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for manufacturing a magnetic recording medium, and more particularly to a method for manufacturing a magnetic recording medium in which the orientation of magnetic powder is good and the electromagnetic conversion characteristics are excellent.

[Background technology]

Generally, magnetic recording media such as magnetic tapes are produced by applying a magnetic paint consisting of magnetic powder, a binder component, an organic solvent, and other necessary components onto a base film using a coating machine.
While the coating film is in an undried state, it is introduced into an orienting magnetic field to orient the axis of easy magnetization of the magnetic powder in the magnetic coating film in the longitudinal direction, and then dried in a dryer.

However, simply introducing an undried magnetic coating into an orienting magnetic field causes the base film to fluctuate, making it difficult to stabilize and transport the base film to a position where the orienting effect is greatest. This method is difficult and has the disadvantage that magnetic powder cannot yet be oriented sufficiently. Therefore, in recent years, the 8th
As shown in the figure and FIG. 9, a base film 2 coated with an undried magnetic coating film 1 is passed through a backing roll 3,
When traveling in the direction of arrow A and performing magnetic field alignment treatment between a pair of N-N opposing magnets 41 and 42 or a solenoid coil 5.5, a flexible synthetic resin smoothing sheet attached to the seat roll 6 is used The orientation of the magnetic powder is improved by a method such as bringing the treated sheet 7 into contact with the surface of the undried magnetic coating 1 and performing a magnetic field orientation treatment while performing a smoothing treatment (Japanese Patent Publication No. 56-856). Attempts have been made to do so, but satisfactorily results have not yet been obtained.

[Purpose of the invention]

In view of the current situation, this invention was made as a result of various studies aimed at obtaining a magnetic recording medium with excellent electromagnetic conversion characteristics by sufficiently improving the orientation of magnetic powder. When an undried magnetic coating film formed by coating is introduced into an alignment magnetic field for orientation treatment, the magnetic coating is The axis of easy magnetization of the magnetic powder in the film is well oriented in the longitudinal direction, achieving the intended purpose.

[Summary of the invention]

This invention involves applying a magnetic coating onto a base film, and then introducing the undried coating into an orienting magnetic field to orient the axis of easy magnetization of the magnetic powder in the magnetic coating in the longitudinal direction. This method is characterized by orienting a high magnetic permeability metal material while bringing it close to or in contact with an undried magnetic coating film.During magnetic field orientation treatment, the high magnetic permeability metal material is brought into close proximity to or in contact with an undried magnetic coating film. Therefore, the magnetic flux for orientation is concentrated on the high magnetic permeability metal material that is very close to the undried magnetic coating, and this concentrated magnetic flux acts extremely effectively on the magnetic powder in the undried magnetic coating. .

Therefore, the magnetic powder in the undried magnetic coating film is well oriented in the longitudinal direction, and a magnetic recording medium with excellent electromagnetic characteristics can be obtained.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 7, which show embodiments of the invention.

In FIGS. 1 and 2, reference numeral 8 denotes a flexible smoothed sheet formed by adhering a metal film 10 of high magnetic permeability to the surface of a synthetic resin film 9, which is attached to a sheet mounting seat roll 11, and is attached to a backing roll. The synthetic resin film 9 side is arranged so as to be in contact with the undried magnetic coating film 1 on the base film 2 running in the direction of arrow A through the magnetic film 3 .

Thus, the undried magnetic coating film 1 coated and formed on the base film 2 is connected to a pair of N-N opposing magnets 41 and 42,
Alternatively, when the magnetic field alignment treatment is performed between the solenoid coils 5 and 5, the magnetic flux for alignment is concentrated on the high magnetic permeability metal film 10 formed on the synthetic resin film 9, and this undried magnetic coating film 1 In order to act on the magnetic powder inside, the magnetic powder in the undried magnetic coating film 1 is well oriented in the longitudinal direction, and at the same time, the magnetic coating is By smoothing the surface of the film 1, a magnetic recording medium with excellent electromagnetic characteristics is obtained.

As described above, the magnetic permeability of the high magnetic permeability metal 11fAlO in the flexible smoothed sheet 8 formed by depositing the high magnetic permeability metal film 10 on the synthetic resin film 9 is lower than 200. N-N opposing magnets 41, 4
2 or solenoid 5.5 cannot be sufficiently concentrated, it is preferable to use one having a magnetic permeability of 200 or more, and one having a high magnetic permeability of 1000 or more is more preferably used. Examples of metals with such high magnetic permeability include permalloy (pe-Ni alloy), Mo
, C, r, Cu, 't/ and W etc. at least 1
Multi-component permalloy containing more than one species, Fe-3i alloy,
Pure iron, Fe-3i-A1 alloy, Fe-C.

ferrites such as alloys, Fe-N1-Go gold alloys, Mn-Zn, etc. are preferably used, and these metals with high magnetic permeability are deposited on the synthetic resin film 9 by vapor deposition or sputtering, etc. A magnetically permeable metal film 10 is formed.

Moreover, as the synthetic resin film 9, films of polyacetate, polyester, polycarbonate, nylon 6, polypropylene, crosslinked polyethylene, tetrafluoroethylene, etc. are preferably used.

The flexible smoothing sheet 8 in these examples includes a high magnetic permeability metal film 10 deposited on a synthetic resin film 9 as shown in FIGS. 3 and 4.
It may also be used in direct contact with the undried magnetic coating film 1; in this case, the high magnetic permeability metal film 10 is in direct contact with the magnetic coating film l.
, the magnetic flux concentrated in this high magnetic permeability metal film 10 acts more effectively on the magnetic powder in the undried magnetic coating 1, and the magnetic powder in the undried magnetic coating 1 is extremely Good longitudinal orientation. In addition, the flexible smoothing treated sheet 8 in these examples is constructed by depositing a high magnetic permeability metal film 10 on a synthetic resin film 9. The treated sheet is not necessarily limited to those shown in these examples, and may be a high magnetic permeability metal sheet (12) formed into a sheet shape by rolling a high magnetic permeability metal as shown in FIG. . In this case as well, since the high magnetic permeability metal sheet 12 is in direct contact with the magnetic coating film 1, the magnetic flux concentrated on the high magnetic permeability metal sheet 12 is more effectively applied to the magnetic powder in the undried magnetic coating film 1. As a result, the magnetic powder in the wet magnetic coating 1 is oriented very well in the longitudinal direction.

Furthermore, as shown in FIG. 6, the smoothing sheet 8 is
The backing roll 3 may be placed in contact with the undried magnetic coating 1 on the base film 2 running in the direction of arrow A above magnets 43 and 44 with different magnetic poles arranged in parallel. Either the synthetic resin film 9 or the high magnetic permeability metal film 10 of the smoothing sheet 8 may come into contact with the undried magnetic coating film 1. In this case as well, the high magnetic permeability metal film 1 formed on the synthetic resin film 9 is similar to the above.
The magnetic flux for orientation is concentrated on the undried magnetic coating film 1.
Because it acts on the magnetic powder inside, the magnetic powder in the undried magnetic coating 1 is well oriented in the longitudinal direction, and at the same time, the surface of the magnetic coating 1 is smoothed, resulting in excellent electromagnetic conversion characteristics. A magnetic recording medium is obtained. In addition, instead of the smoothing sheet 8, as shown in FIG. 7, a ball-shaped metal plate 13 made of a high magnetic permeability metal is placed in parallel with magnets 43 having different magnetic poles through a packing roll 3. .44 may be arranged so as to be in contact with the undried magnetic coating film 1 on the base film 2 running upward in the direction of arrow A (in this case, the sixth
Effects similar to those shown in the figure can be obtained.

In any of the above cases, the smoothing sheet 8, high magnetic permeability metal sheet 12, and ball-shaped high magnetic permeability metal plate 13 do not necessarily have to be in contact with the undried magnetic coating 1. Often, a sufficient effect can be obtained if the magnets or solenoid are close enough to each other to concentrate their magnetic flux.

As the magnetic powder used in this invention, for example, T
-Fe203 powder, Fe3O4 powder, CO-containing r-Fe
Various conventionally known magnetic powders such as 203 powder, Co-containing Fe3O4 powder, crO2 powder 1, Fe powder, and Co powder are widely included, and binder resins include vinyl chloride-vinyl acetate copolymer and polyvinyl butyral resin. , cellulose resin, polyurethane resin, polyester resin,
Conventionally widely used binder resins such as isocyanate compounds are widely used.

Further, as the organic solvent, conventionally widely used organic solvents such as toluene, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, and ethyl acetate are used alone or in a mixture of two or more.

Furthermore, the coating machines that apply the magnetic paint prepared by mixing and dispersing these magnetic powders, binder resin, organic solvent, etc. onto the base film include knife coaters, gravure coaters, reverse roll coaters, and bead coaters. , Kiss coater, Gui coater, Curtain coater, and other conventionally used coaters are preferably used.

Incidentally, various commonly used additives such as a dispersant, a 7I21 lubricant, an abrasive, an antistatic agent, etc. may be optionally added to the magnetic paint.

〔Example〕

Next, embodiments of the invention will be described.

Example 1 r-Fe203 magnetic powder 100 parts by weight VAGH
(Manufactured by U, C, C, USA, vinyl salt 16-vinyl acetate-vinyl alcohol copolymer) Carbon black 2 Lauric acid
0.5 Dioctyl phthalate
4 Methyl isobutyl ketone 7
5〃Toluene 75〃This composition was mixed and dispersed in a ball mill for 72 hours to prepare a magnetic paint, and this magnetic paint was coated on a polyester base film 2 with a thickness of 12μ using a knife coater so that the dry thickness was 6μ. It was painted on. Next, as shown in FIG. 1, while bringing the synthetic resin film 9 side of the flexible smoothing sheet 8, which has a high magnetic permeability metal film 10 on the synthetic resin film 9, into contact with the magnetic coating II 1, N-N opposing magnet 4
After applying magnetic field orientation treatment at 1.42 and drying,
Magnetic tape was made by cutting it to a specified width. The smoothing sheet 8 was a polyester film on which permalloy (Ni-Fe alloy, weight ratio 78:12) was deposited to a thickness of 0.1 μm. The initial permeability of this permalloy is 5oo
It was o. Further, the strength of the orientation magnetic field of the N--N opposing magnets 41 and 42 was 2000 Gauss.

Example 2 As the smoothed sheet 8, 0.1 permalloy (Ni-Fe alloy, weight ratio 45:55) was made by sputtering.
A magnetic tape was produced in the same manner as in Example 1, except that an acetate film deposited to a thickness of μ was used and the magnetic field alignment treatment was performed using a solenoid 5 as shown in FIG. The initial magnetic permeability of this permalloy was 1500. Further, the strength of the orientation magnetic field of the solenoid 5 was 2000 Gauss.

Example 3 The same procedure as in Example 1 was carried out except that the smoothed sheet 8 in Example 1 was replaced with a smoothed sheet 8 made of a polyester film coated with pure iron to a thickness of 0.1 μm by vapor deposition. I made magnetic tape. The initial magnetic permeability of this pure iron was 500.

Example 4 In Example 1, the smoothed sheet 8 was treated with Mn-Zn ferrite (weight ratio 1:1) by sputtering.
) was replaced with a smoothed sheet 8 made of a polyester film adhered to a thickness of 0.1 μm, and a magnetic tape was made in the same manner as in Example 1. The initial magnetic permeability of this M n -Z n ferrite was as follows: It was 800.

Example 5 As shown in FIG. 3, a high magnetic permeability metal coating 0 of the same smoothed sheet 8 used in Example 1 was applied in a magnetic field while being brought into contact with the magnetic coating 1 on the polyester base film 2. A magnetic tape was produced in the same manner as in Example 1, except for the orientation treatment.

Example 6 As shown in FIG. 6, the synthetic resin film 9 side of the same smoothing sheet 8 used in Example 1 was run over magnets 43 and 44 with different magnetic poles arranged in parallel. A magnetic tape was produced in the same manner as in Example 1, except that the magnetic tape was subjected to the magnetic field orientation treatment while being brought into contact with the undried Hiromembrane 1 on the base film 2. The strength of the orientation magnetic field of magnet 43.44 is 2
000 Gauss.

Example 7 Example 6 is the same as Example 6, except that instead of the smoothing sheet 8, a ball-shaped high magnetic permeability metal plate 13 is used, and the magnetic field orientation treatment is performed as shown in FIG. A magnetic tape was made in the same manner as in 6.

The initial magnetic permeability of the bead-shaped high magnetic permeability gold mud plate 13 was 4000.

Comparative Example 1 A magnetic tape was fabricated in the same manner as in Example 1, except that the smoothed sheet 8 in Example 1 was replaced with a smoothed sheet made only of polyester film.

Comparative Example 2 A magnetic tape was produced in the same manner as in Example 2, except that the smoothed sheet 8 was replaced with a smoothed sheet made only of acetate film.

Comparative Example 3 A magnetic tape was produced in the same manner as in Example 1, except that the smoothed sheet 8 in Example 1 was replaced with a smoothed sheet made of a polyester film coated with soft iron to a thickness of 0.1 μm by vapor deposition. I made it.

The initial permeability of soft iron was 100.

The squareness ratio and sensitivity at 33311z and 12.5KIlz were measured for the magnetic tapes obtained in each example and each comparative example.

The table below shows the results.

Table [Effects of the Invention] As is clear from the above table, the magnetic tapes obtained by the present invention (Examples 1 to 7) have a square ratio compared to the magnetic tapes obtained in Comparative Examples 1 to 3. The results show that according to the manufacturing method of the present invention, the magnetic powder is well oriented in the longitudinal direction, and a magnetic recording medium with excellent electromagnetic characteristics can be obtained.

[Brief explanation of drawings]

Figures 1 to 7 are explanatory diagrams showing an outline of the magnetic field orientation treatment of the present invention in the manufacturing process of a magnetic tape, and Figures 8 and 9 are explanatory diagrams showing an outline of the conventional magnetic field orientation treatment in the manufacturing process of the same magnetic tape. FIG. 1... Magnetic coating film, 2... Base film, 41.42
... N-N opposing magnet, 43.44... Magnet, 5...
・Solenoid, 8... Smoothing sheet, 9... Synthetic resin film, 10... High magnetic permeability metal film (high magnetic permeability metal material), 12... High magnetic permeability metal sheet (high magnetic permeability Metal material), 13... Ball-shaped high magnetic permeability metal plate (high magnetic permeability metal material) Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8

Claims (1)

[Claims] 1. Applying a magnetic coating onto a base film, and then introducing it into an orienting magnetic field without drying it to orient the axis of easy magnetization of the magnetic powder in the magnetic coating in the longitudinal direction. A method for producing a magnetic recording medium, which comprises orienting a magnetic metal material in close proximity to or in contact with an undried magnetic coating film.