JPH0223523A - Method and apparatus for producing magnetic recording medium - Google Patents

Abstract

PURPOSE:To form a uniform magnetic layer which is free from unequal coating thicknesses and to prevent elongation and deformation by magnetizing only the specific parts of a gravure roll and coating a film with a magnetic coating compd. CONSTITUTION:The magnetization of the parts of the gravure roll 1 corresponding to both edges of the traveling polyester film 5 is executed by disposing annular magnets 7 polarized alternately with N-S poles in the circumferential direction to the positions in the roll 1 corresponding to both edges of the film 5 in such a manner that the magnetic lines of force thereof reach the surface of the roll 1. The magnetic coating compd. 3 to be applied on both edges of the film 5 is attracted by such magnetic lines of force, by which the application of the paint 3 is suppressed and the uniform magnetic layer is formed.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention provides a method for applying magnetic paint onto a base film using a gravure roll to form a magnetic layer to form a magnetic recording medium material. The present invention relates to a method and apparatus for manufacturing magnetic recording media efficiently and inexpensively with a good yield by preventing thickness unevenness in a recording medium raw fabric and forming a magnetic recording medium raw fabric without elongation deformation.

[Conventional technology]

Generally, as shown in FIG. 7, a magnetic recording medium is produced by dipping the lower part of a gravure roll 1 into a magnetic paint 3 in a magnetic paint tank 2 and rotating it in the direction shown by arrow A. After scraping off excess magnetic paint adhering to the surface, a base film 5 such as a polyester film is run between a gravure roll 1 and an impression roll 6 rotating in the direction of arrow B with respect to the gravure roll 1. The magnetic coating material 3 is coated on the base film 5 and dried to form a magnetic recording medium material, which is then cut into an appropriate shape. (Ken Uematsu--) Noboru Se, "Revolution in Magnetic Materials," July 10, 1985, Kogyo Kenkyukai, p. 173) [Problem to be solved by the invention] However, the method using such a conventional gravure coating machine However, this method has the disadvantage that the coating thickness near both edges of the magnetic recording medium material is thicker when it is applied while being pressed by the impression roll 6, and if it is wound into a roll as it is, that part will bulge and deform. The deformed portion becomes unusable as a magnetic recording medium.

[Means to solve the problem]

This invention was made as a result of various studies in view of the current situation, and when applying magnetic paint onto a base film using a gravure roll, it is possible to apply the magnetic paint by magnetizing only a specific part of the gravure roll. , magnetic paint is attracted to the magnetized part of the gravure roll using magnetic force, and this magnetized part reduces the amount of magnetic paint applied onto the base film, adjusting the thickness of the magnetic layer to be formed, and reducing uneven coating thickness. By forming a uniform magnetic layer with no deformation, it is possible to obtain an original magnetic recording medium free from elongation and deformation. Moreover, the magnetic recording medium obtained by appropriately cutting this magnetic recording medium original fabric can be manufactured efficiently and inexpensively with a high yield.

Hereinafter, a magnetic recording medium manufacturing apparatus used in the present invention will be explained with reference to the drawings.

1 and 2 show an example of a magnetic recording medium manufacturing apparatus used in the present invention, in which 1 is a gravure roll whose lower part is dipped into a magnetic paint 3 in a magnetic paint tank 2. and rotate in the direction of arrow A.

Reference numeral 4 denotes a doctor blade, the tip of which touches the circumferential surface of the gravure roll 1, and rotates the gravure roll 1.
This is to scrape off the excess magnetic paint 3 that has adhered to the surface and been pulled up.

5 is a continuously running polyester film; 6 is a rubber impression roll that presses the polyester film 5 against the gravure roll 1 and rotates in the direction of arrow B; A predetermined amount of magnetic paint 3 is applied onto the polyester film 5 running between the two to form a magnetic layer.

Reference numeral 7 denotes a ring-shaped magnet disposed inside the gravure roll 1 corresponding to both ears of the polyester film 5 that is running, and the magnetic force of the ring-shaped magnet 7 causes the magnet to be attached to both ears of the polyester film 5 that is running. The applied magnetic paint 3 is attracted, and the application of the magnetic paint 3 to both ears of the polyester film 5 is suppressed.

Therefore, when the magnetic paint 3 is applied to the polyester film 5 traveling between it and the gravure roll 1 by the pressure of the impression roll 6, the amount of the magnetic paint 3 applied to both edges of the polyester film 5 decreases. , the thickness of the magnetic coating material 3 at both ears is adjusted to be thin, a uniform magnetic layer is formed, and the original magnetic recording medium has an even thickness even when wound on a winding roll and does not undergo elongation deformation. is obtained.

In this way, the magnetization of the portions corresponding to both ears of the polyester film 50 on which the gravure roll 1 runs is controlled by a ring in which N-3 poles are alternately polarized in the circumferential direction, as shown in FIGS. 1 to 3. A shaped magnet 7 is arranged at a position corresponding to both ears of the polyester film 50 in the gravure roll 1 so that its magnetic lines of force 8 reach the surface of the gravure roll l, and the action of the magnetic lines of force 80 causes the polyester film 50 to The magnetic paint 3 applied to both ears is attracted, the application of the magnetic paint 3 is suppressed, and a uniform magnetic layer is formed. At this time, the strength of the magnetic lines of force 8 is preferably 10 Gauss or more in order to effectively act on the surface of the gravure roll 1.

The magnets disposed at positions corresponding to both ears of the polyester film 5 in the gravure roll 1 may be ring-shaped magnets 71 with N-3 poles polarized on the front and back sides, as shown in FIG. As shown in Figure 5, single magnets with N-3 poles alternately polarized in the circumferential direction are arranged to form a ring-shaped magnet 72, or as shown in Figure 6, N-3 poles are polarized on the front and back sides. A ring-shaped magnet 73 may be formed by arranging a single magnet, and the same effect can be obtained by either method.

In this way, when the magnetic paint 3 is applied onto the base film 5 using a gravure roll equipped with ring-shaped magnets 73, less magnetic paint is applied to both edges of the polyester film 5, The thickness of the magnetic coating material 3 at both ears is adjusted to be thin (thin), a uniform magnetic layer is formed, and even when wound on a winding roll, there is no thickness unevenness, and the original magnetic recording medium is free from elongation and deformation. As a result, there is no need to discard the areas near both ears of the original magnetic recording medium as defective products, which improves the yield of magnetic recording media and makes it possible to manufacture magnetic recording media efficiently (and at low cost). I can do it.

〔Example〕

Next, an embodiment of this invention Φ will be described.

Example 1 cx-FeT! i-type powder 800 parts by weight S-LEC A (Tanezu Kagaku Kogyo Co., Ltd. 90〃L vinyl chloride-
(Vinyl acetate-vinyl alcohol copolymer) YT-400 (manufactured by Asahi Denka Co., Ltd., polyol) Coronet) L (manufactured by Nippon Polyurethane Industry Co., Ltd.,
Trifunctional low molecular weight isocyanate compound) Carbon black 10#α-A 1
! Ox powder 60 myristic acid
15〃n-butyl stearate
10〃Cyclohexanone 800〃Toluene 800〃Prepare a magnetic paint having the above composition, and as shown in Figs. Then, using a gravure roll 1 having a diameter of 250 mm and equipped with a ring-shaped magnet 7 having an outer diameter of 230 mm, an inner diameter of 210 mm, a width of 10 mm, and a magnetic field of 300 Gauss, magnetic paint was applied, and the thickness after drying was A 5 μm magnetic layer was formed and wound onto a take-up roll. Next, when the magnetic recording medium material wound on the take-up roll was unwound and cut to a predetermined width to make a magnetic tape, no elongation deformation was observed in both ears of the magnetic recording medium material material. , the yield was improved and magnetic tapes were efficiently obtained.

Example 2 In Example 1, a ring-shaped magnet with an outer diameter of 230 mm, an inner diameter of 210 mm, a width of 10 mm, and a magnetic field of 300 Gauss was placed inside corresponding to both ears of the polyester film 5 pressed by the impression roll 6. The diameter with 7 attached is 2
Instead of the 50 mm gravure roll 1, as shown in Fig. 4, a roll with an outer diameter of 230 mm, an inner diameter of 210 mm, and a width of 1 is used.
0mm.

A magnetic tape was produced in the same manner as in Example 1, except that a gravure roll 1 with a diameter of 250 mm was used, which was equipped with a ring-shaped magnet 71 having N-3 poles polarized on the front and back sides with a magnetic field of 300 Gauss. In the thus obtained magnetic recording medium material, as in the case of Example 1, no elongation deformation was observed in both ears, and the yield was improved and a magnetic tape was efficiently obtained.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the conventional magnetic recording medium manufacturing apparatus shown in FIG. 7 was used instead of the magnetic recording medium manufacturing apparatus shown in FIGS. 1 to 3. and made magnetic tape. The magnetic recording medium material obtained in this way had elongation deformation at both ears, and no magnetic tape could be obtained from these ears.

〔Effect of the invention〕

As is clear from Example 1.2 and Comparative Example 1, the magnetic recording medium material obtained in Comparative Example 1 had elongation deformation at both ears, and a magnetic tape could not be obtained from these ears. but,
The magnetic recording medium original fabric obtained by the manufacturing apparatus and manufacturing method of the present invention does not undergo elongation and deformation, and the yield of the magnetic tape obtained by cutting it is improved, so that the magnetic tape can be obtained efficiently and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of the magnetic recording medium manufacturing apparatus used in this invention, FIG. 2 is a schematic front view of the same, and FIG. A front view showing an example, Fig. 3 (B) is a side view of the same, Fig. 4
Figure (A) is a front view showing another example of the same ring-shaped magnet.
Figure (B) is a side view of the same, Figure 5 is a front view showing another example of the same ring-shaped magnet, Figure 6 (A) is a front view showing still another example of the same ring-shaped magnet, Figure 6 (b) is shown in Figure 6 (
A) is a sectional view taken along the line A-A of the ring-shaped magnet, and FIG. 7 is a schematic side view of a conventional magnetic recording medium manufacturing apparatus.

Claims (1)

[Claims] 1. When applying magnetic paint onto a base film using a gravure roll, only a specific part of the gravure roll is magnetized and applied to form a magnetic layer with an adjusted thickness on the base film. 2, a method for producing a magnetic recording medium characterized in that, when applying a magnetic paint onto a base film using a gravure roll, only the portions of the base film that correspond to both ears of the gravure roll wound around the gravure roll; A method for manufacturing a magnetic recording medium characterized by forming a magnetic layer on a base film by magnetizing and adjusting the thickness of both ears 3, magnetizing only a specific part in the magnetic coating process A magnetic recording medium manufacturing apparatus 4 in which a gravure roll is provided, a magnetic paint is adhered to the surface of the gravure roll, and the magnetic paint is applied onto a base film to form a magnetic layer with an adjusted thickness; A gravure roll is installed in which only the parts corresponding to both ears of the base film wound around the gravure roll are magnetized, and a magnetic paint is attached to the surface of this gravure roll and applied on the base film, and both sides are magnetized. A manufacturing device for magnetic recording media that forms a magnetic layer with adjusted ear thickness.