JPH04170719A - Manufacture of magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve an electrical characteristic sharply by a method wherein magnetic coating is applied on a support, two or more permanent magnets are disposed along the direction of the movement of the support and the axis of easy magnetization of magnetic powder particles in a magnetic coating film is oriented in the traveling direction of the support by using these magnets. CONSTITUTION:While a base film 1 is made to run at a prescribed speed, magnetic coating is applied thereon by a coating head 2 and the film is introduced in between N-N facing magnets 5 provided just before a drier 4 while a magnetic coating film 3 is in an undried state. Next, the coating film 3 is led just above a number of perma nent magnets 6a to 6f disposed on the lower side in the drier 4, and dried while mag netic powder particles in the coating film 3 are oriented. The magnets 6a to 6f are arranged so that N-S poles are parallel to the direction of the movement of the support and that different poles are adjacent to each other, spacing between the magnets is made narrower toward the central position of the arrangement, and thereby a magnetic field is made to act so that the polarity of a magnetic field component of the coating film 3 in the direction of the movement of the film 1 may not change. In this way, the particles are oriented in the traveling direction of the film 1 and the squareness is improved sufficiently.

Description

[Detailed Description of the Invention] [Field of Industrial Application] 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 with good orientation of magnetic powder and excellent electrical properties. .

[Conventional technology]

Generally, for magnetic recording media such as magnetic tape, magnetic paint is applied using a coating machine such as a reverse roll or gravure roll while a base film is running at a constant speed, and while the coating film is still wet, The axis of easy magnetization of the magnetic powder particles in the magnetic coating film is aligned with the running direction (longitudinal direction) of the base film by introducing it into a magnetic field orientation device composed of two N-N facing magnets or S-3 facing magnets. It is made by aligning the material along the same direction and then passing it through a dryer to completely dry and harden it. (Special Publication No. 34-2536).

[Problem to be solved by the invention]

However, in this method, the time during which the magnetic field acts on the magnetic coating film is short, so sufficient orientation is not achieved, and the magnetic coating film is drawn out of the magnetic field in an undried state, so that the magnetic powder particles do not interact with each other. The disadvantage is that the action disturbs the longitudinally oriented arrangement of the magnetic powder particles. Therefore,
A method of drying the coating film in a magnetic field using a solenoid coil (Japanese Unexamined Patent Publication No. 141612/1982) has also been considered, but
Since using a solenoid coil for orientation increases production costs, it is desirable to achieve good orientation using permanent magnets.

[Means for Solving the Problems] This invention was made as a result of intensive studies to solve the above problems, and consists of coating a magnetic paint on a support, and then attaching two or more permanent magnets to the support. While the running supports move from the beginning to the end of the arrayed permanent magnets, the polarity of the magnetic field component in the running direction of the supports changes in the magnetic coating film on the supports. By introducing the support into a magnetic field and running it, the axis of easy magnetization of the magnetic powder particles in the magnetic coating film is well oriented in the running direction of the support, and the electricity of the magnetic recording medium is It has sufficiently improved physical characteristics.

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

FIG. 1 shows an outline of a method for manufacturing a magnetic recording medium according to the present invention. In this method, a coating head 2 coats magnetic paint on the base film 1 while the base film 1 is running at a constant speed. While the magnetic coating film 3 formed by coating is in an undried state, it is introduced between N and N opposing magnets 5.5 disposed immediately before the dryer 4.

Subsequently, it is introduced into the dryer 4 and directly above a large number of permanent magnets 6a to 6f arranged at the lower part of the dryer 4, where it is dried while orienting the magnetic powder particles in the magnetic coating 3. . Here, each of the permanent magnets 6a to 6f is arranged such that the N-3 poles are substantially parallel to the running direction of the support and different poles are adjacent to each other, and the intervals between the permanent magnets are are arranged in parallel so that the closer they are to the center, the narrower they are.
While the running base film 1 moves from the permanent magnet 6a at the beginning of the permanent magnets 62 to 6f to the permanent magnet 6f at the end, the magnetic coating 3 on the base film 1 is coated with the magnetic coating 3 in the running direction of the base film 1. The magnetic field is applied so that the polarity of the magnetic field component does not change.

When the base film 1 provided with the magnetic coating film 3 is introduced between the N-N opposing magnets 5, 5 disposed immediately before the dryer 4, the N-N opposing magnets 5,5 As a result, the magnetic powder particles in the magnetic coating are oriented in the running direction of the base film 1.

Further, inside the dryer 4, the N-3 poles are arranged so that the N-3 poles are almost parallel to the running direction of the support and different poles are adjacent to each other, and the intervals between each permanent magnet are set at the center of the arranged permanent magnets. When introduced directly above the permanent magnets 6a to 6f, which are arranged in large numbers in parallel, the closer the position is While moving from 6a to the permanent magnet 6f at the end, a magnetic field acts on the magnetic coating 3 on the base film 1 so that the polarity of the magnetic field component in the running direction of the base film 1 does not change. , the magnetic powder particles in the magnetic coating film 3 are oriented along the running direction of the base film 1, and this orientation continues until the magnetic coating film loses its fluidity.Therefore, the magnetic powder particles in the magnetic coating film 3 is easily and favorably oriented in the running direction of the base film 1, the squareness is sufficiently improved, and the electrical properties are sufficiently improved.

Inside the dryer 4, the N-3 poles are arranged so that they are almost parallel to the running direction of the support and different poles are adjacent to each other, and the intervals between the permanent magnets are set close to the center position of the arranged permanent magnets. A large number of permanent magnets 6a are arranged in parallel in such a way that they become as narrow as possible.
~6f, the magnetic field from these permanent magnets 6a~6f is
While the running base film 1 moves from the permanent magnet 6a at the beginning to the permanent magnet 6f at the end, the polarity of the magnetic field component in the running direction of the base film 1 changes on the magnetic coating 3 on the base film 1. In order to make it work without changing,
Base film 1 running directly above permanent magnets 6a to 6f
These permanent magnets 6a to 6f are connected by adjusting the distance between them as appropriate.
It is preferable that the magnetic field strength of the adjacent permanent magnets 6a to 6a is within the range of 50 to 2000 Gauss.
The spacing between 6fs varies depending on the shape of the permanent magnet used, but the spacing closest to the center of the permanent magnet array should be 0 to 20 mm, and the spacing at the end should be 5 to 200 mm. is preferable. Furthermore, since magnetic powder particles can be better oriented when the magnetic field strength changes less, the support moves from the permanent magnet 6a at the beginning of the arrayed permanent magnets 6a to 6f to the permanent magnet 6f at the end. During this period, the minimum value of the strength of the magnetic field acting on the magnetic coating film 3 on the base film 1 directly above or directly below the gap between each of the permanent magnets 6a to 6f is determined as the maximum value of the strength of the magnetic field acting on the same magnetic coating film 3. It is preferable to make it 215 to 1 times.

Incidentally, since the magnetic powder particles in the magnetic coating film 3 are sufficiently oriented by the permanent magnets 6a to 6f disposed in the dryer 4, the N-N opposing magnets 5. Although magnets 5 and 5 are not necessarily required, if an N--N facing magnet 5.5 is provided immediately in front of the dryer 4, better orientation can be achieved.

In addition, the N-3 poles are arranged so that they are almost parallel to the running direction of the support and different poles are adjacent to each other, and the intervals between the permanent magnets are set so that the closer they are to the center of the arranged permanent magnets, the narrower they are. The permanent magnets 6a to 6f arranged in large numbers in parallel need only be able to apply the magnetic field from the permanent magnets 6 until the magnetic coating film 3 coated and formed on the base film 1 loses its fluidity; Although it is not necessary to arrange it within the dryer 4, if it is arranged inside the dryer 4 and oriented while drying, rapid orientation can be performed and production efficiency can be improved.

FIG. 2 schematically shows another example of the method for manufacturing a magnetic recording medium of the present invention, in which N-5 poles are placed almost parallel to the running direction of the support and different poles are adjacent to each other in the dryer 4. A running base film 1 includes a large number of permanent magnets 6a to 6f arranged in parallel so that the distance between the permanent magnets becomes narrower as the distance between the permanent magnets approaches the center of the arranged permanent magnets.
Except for arranging the upper and lower levers with the same poles opposing each other,
The configuration is similar to that shown in FIG.

According to this manufacturing method, the N-3 poles are arranged so that they are almost parallel to the running direction of the support and different poles are adjacent to each other, and the distance between each permanent magnet is set at the center of the arranged permanent magnets. A large number of permanent magnets 6a to 6f are arranged side by side, narrowing closer to the position, and are arranged on both sides of the running base film 1 with the same polarity facing each other, so that the upper and lower opposed permanent magnets 6a to 6f 6f, 6a to 6r, while the running base film l moves from the permanent magnet 6a at the beginning end to the permanent magnet 6f at the end end, the monochrome coating Ill 3 on the base film 1 is applied in the running direction of the base film 1. The magnetic field acts so that the polarity of the magnetic field component does not change, and moreover, it is possible to apply a stronger magnetic field than in the case shown in FIG. 1, so that the magnetic powder is better oriented.

In this case, these upper and lower permanent magnets 6a to 6f.

In order to ensure that the magnetic fields from 6a to 6f work well, the distance between the upper and lower permanent magnets 6a to 6f, 6a to 6f and the base film 1 that runs between these permanent magnets 6a to 6f, 6a to 6f is set. These permanent magnets 6a are adjusted appropriately.
It is preferable that the strength of the magnetic field of ~6f, 6a~6f is within the range of 50~2000 Gauss, and the spacing between adjacent permanent magnets 6a~6f is set using the same permanent magnets as in the case of Fig. 1. Although it varies depending on the shape of the magnet, it is preferable that the spacing closest to the center of the permanent magnet array is 0 to 20 m, and the spacing at the end is 5 to 200 m. Furthermore, as in the case of FIG.
The minimum strength of the magnetic field acting on the magnetic coating 3 on the base film 1 between the gaps between the permanent magnets 6a to 6f and 6a to 6f while the support moves from 6a to the permanent magnets 6f and 6f at the end. It is preferable that the value is 215 to 1 times the maximum value of the strength of the magnetic field acting on the same magnetic coating film 3.

When preparing magnetic paint, the magnetic powder used is:
7FezOx powder, Fe30n powder, Co-containing 7-Fe
z0 = powder, CO-containing Fe3O4 powder 1, Fe powder, F
Any of the materials commonly used in the past can be suitably used, such as a metal powder containing e as a main ingredient and various metals added thereto, a CO powder, a Ni powder, or an alloy powder thereof.

In addition, conventionally widely used binder resins such as vinyl chloride-vinyl acetate copolymers, polyvinyl butyral resins, cellulose resins, polyurethane resins, polyester resins, and isocyanate compounds are widely used as binder resins. It will be done.

As the organic solvent, conventionally used organic solvents such as toluene, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, and ethyl acetate can be used alone or in combination of two or more.

Note that various commonly used additives such as dispersants, lubricants, fillers, antistatic agents, etc. may be optionally added to the magnetic coating material.

〔Example〕

Next, embodiments of the invention will be described.

Example I CO-containing T Fe2O 280 parts by weight (coercive force 630 oersted) Vinyl chloride-vinyl acetate-vinyl 9 Alcohol copolymer polyurethane resin 9 Trifunctional low molecular weight isocyanate 2 Compound methyl isobutyl ketone 60 Toluene
60〃This composition was milled in a ball mill.
A magnetic paint was prepared by mixing and dispersing for 6 hours. As shown in FIG. 1, this magnetic paint is applied onto a polyester base film 1 with a thickness of 12 μm using a coating head 2, and while this is in an undried state, an N-N opposing magnet 5,
Then, the distance between the polyester heath film 1 and the permanent magnets 6a and 6b is set to 25 mm, and the space between the permanent magnets 6a and 6b is set to 201 mm! ll11, the distance between permanent magnets 6b and 60 is 10 disks, and the distance between permanent magnets 6C and 6 is
d, the distance between the permanent magnets 6d and 6e is 1011D11, and the distance between the permanent magnets 6e and 6f is 20mo+. Hot air drying was performed to form a magnetic layer with a dry thickness of 6 μm. After that, it was cut to a specified width to make magnetic tape.

Examples 2 to 5 In the magnetic field orientation in Example 1, the magnetic field orientation device shown in FIG. 2 was used instead of the magnetic field orientation device shown in FIG. 1, and the distance between the permanent magnets 6a and 6b arranged vertically was 20
-1 The distance between permanent magnets 6b and 6C is Loan, the distance between permanent magnets 6c and 6d is 2fMi, the distance between permanent magnets 6d and 6e is 10mm, and the distance between permanent magnets 6e and 6f is 20mm.
mm, and the distance between these permanent magnets 6a to 6f, 6a to 6f and the base film 1 is set to 20 mm as shown in Table 1 below. Magnetic tapes were produced in the same manner as in Example 1, except that the orientation treatment was performed with various plates ranging from 11 to 50 plates.

FIG. 3 is a graph showing the magnetic field strength in the longitudinal direction of the base film i when the orientation treatment is performed in Examples 2 to 5. In this graph, the sign of the magnetic field strength in the longitudinal direction is , when the magnetic field component in the longitudinal direction is in the same direction as the running direction of the base film 1, is (+);
The reverse direction is indicated by (-). As is clear from these graphs, the magnetic field strength in the running direction is positive in all cases, and therefore, in the orientation processing in Examples 2 to 5, the magnetic field strength is It can be seen that the magnetic field acts on the magnetic coating film 3 on the base film 1 so that the polarity of the magnetic field component in the running direction of the base film 1 does not change while the film moves to the final permanent magnet 6f.

Comparative Example 1 In Example 1, the permanent magnet 6 placed inside the dryer 4
A magnetic tape was prepared in the same manner as in Example 1 except that a to 6f were omitted.

Comparative Example 2 A magnetic tape was produced in the same manner as in Example 2, except that the intervals between the permanent magnets 6a to 6f and 6a to 6f were made equal.

FIG. 4 is a graph showing the magnetic field strength in the longitudinal direction of the base film 1 when the orientation treatment is performed in Comparative Example 2. In this graph, the sign of the magnetic field strength in the longitudinal direction is determined by the longitudinal direction. When the magnetic field component is in the same direction as the running direction of the base film 10, it is represented by (+), and when it is in the opposite direction, it is represented by (-). As is clear from this graph, the magnetic field strength in the running direction changes from positive to negative every time it passes between each permanent magnet, and from this, in the orientation process in Comparative Example 2, permanent magnets 6a to 6r, 6a ~6f
from the first permanent magnet 6a, 6a to the final permanent magnet 6f,
While moving up to 6f, the magnetic 2M3 on the base film 1
It can be seen that a magnetic field in which the polarity of the magnetic field component in the running direction of the base film 1 is reversed is acting.

In addition, in the orientation treatment in each example and comparative example, while the base film 1 moves from the first permanent magnet 6a to the final permanent magnet 6r of the arranged permanent magnets 6a to 6f, the gap between each permanent magnet 6a to 6f is Measure the minimum value G of the strength of the magnetic field acting on the magnetic coating film 3 on the base film 1 directly above or directly below the magnetic coating film 3, and the maximum value GL of the strength of the magnetic field acting on the same magnetic coating film 3, and calculate the ratio. G s / GL was determined, and the squareness ratio was also measured for the magnetic tapes obtained in each example and comparative example.

Table 1 below shows the results.

Table 1 [Effects of the Invention] As is clear from Table 1 above, the magnetic tapes (Examples 1 to 5) obtained by the manufacturing method of the present invention were superior to those obtained in Comparative Examples 1 and 2. In comparison, all of them have high squareness, which shows that according to the manufacturing method and apparatus of the present invention, the magnetic powder particles are well oriented and a magnetic recording medium with excellent electrical properties can be obtained. .

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an outline of an example of the manufacturing process of the magnetic tape of the present invention, FIG. 2 is an explanatory diagram showing an outline of an example of the same process,
FIG. 3 is an explanatory graph showing the magnetic field strength in the longitudinal direction of the base film 1 when the orientation treatment is performed in Examples 2 to 5, and FIG. FIG. 2 is an explanatory diagram showing the magnetic field strength in the longitudinal direction of the film 1 in a graph. DESCRIPTION OF SYMBOLS 1... Base film (support), 3... Magnetic coating film, 4... Dryer, 6a, 6b, 6c, 6d, 6e. 6f...Permanent magnet patent applicant Hitachi Maxell, Ltd.

Claims (1)

[Claims] 1. Apply magnetic paint on a support, and then arrange two or more permanent magnets along the running direction of the support to form the first permanent magnet in which the running supports are arranged. While moving from end to end, the support is introduced into a magnetic field that acts on the magnetic coating on the support so that the polarity of the magnetic field component in the running direction of the support does not change, and the magnetic coating is A method for manufacturing a magnetic recording medium characterized by orienting the axis of easy magnetization of the magnetic powder particles in the film in the running direction of the support 2. Two or more permanent magnets are placed either above or below the support. The N-S poles of each permanent magnet are arranged on the side of The polarity of the magnetic field component in the running direction of the support is applied to the magnetic coating film on the support while the running support moves from the beginning to the end of the arrayed permanent magnets. 3. A method for producing a magnetic recording medium according to claim 1, wherein the magnetic field is applied such that the 3. The magnetic recording medium according to claim 1, wherein the minimum strength of the magnetic field acting on the magnetic coating film on the support is 2/5 to 1 times the maximum strength of the magnetic field acting on the same magnetic coating film. manufacturing method