JPH0352133B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a magnetic medium that allows the surface of an overcoat layer that contacts a magnetic head to be extremely smooth.

[Conventional technology]

Traditionally, magnetic materials are coated on the base, such as magnetic tape, magnetic floppies, magnetic cards, etc.
Magnetic media, in which various information is magnetically stored in this magnetic material using a magnetic head, have been widely used. This conventional magnetic medium is formed by coating a magnetic material such as strontium ferrite or barium ferrite on a plastic base such as polyethylene. however,
If the magnetic head is brought into direct contact with magnetic material, the particles of the magnetic material will wear out the magnetic head.
An overcoat layer that forms a smooth surface with sliding properties is always applied to the surface of the magnetic material. This overcoat layer made the surface of the magnetic medium smooth and acted as a lubricant even when the magnetic head came into contact with it, thereby preventing wear of the magnetic head. Now, in recent years, it has begun to manufacture magnetic tapes, magnetic disks, and magnetic cards using strontium ferrite instead of barium ferrite as a material and utilizing its high antimagnetic properties. This is because, due to its high magnetic density, it can be used for perpendicular magnetic information recording, etc., using the same manufacturing process technology as in the past. However, compared to the conventionally used barium ferrite, strontium ferrite has the problem that the size of the magnetic particles is unstable when applied to the base, and the shape of the particles becomes large. Even if an overcoat layer was attached to the surface, irregularities often occurred.

The cross-sectional structure of this conventional magnetic medium is explained with reference to Figure 1.The base 1 is made of polyethylene, etc., and the surface of the base 1 is made of a mixture of a magnetic material such as strontium ferrite and a binder such as glue. The magnetic layer 2 is coated and fixed,
An extremely thin overcoat layer 3 is applied to the surface of the magnetic layer 2. However, since these magnetic particles in the magnetic layer 2 containing strontium ferrite have large sizes as described above, even if a thin overcoat layer 3 is applied, the unevenness will be exposed on the surface of the overcoat layer 3. Therefore, the overcoat layer 3 itself has irregularities. For this reason, when a magnetic head is brought into contact with and slid on the overcoat layer 3, the magnetic head is worn out, making it impossible to write or read information stably over a long period of time. In order to prevent this drawback, the surface of the overcoat layer 3 is sometimes polished and smoothed in the manufacturing process of magnetic media, but there are limits to the smoothing work, and The coater device for the overcoat layer 3 wears out quickly, leaving various problems.

[Problem that the invention seeks to solve]

The present invention provides a method for manufacturing a magnetic medium that can smooth the surface of the overcoat layer even when using a magnetic material with large particles such as strontium ferrite, and can reduce wear on the magnetic head and damage to the coater. It provides:

[Means for solving problems]

In the present invention, a thin overcoat layer is brought into contact with a smooth surface, a magnetic layer is applied to the back side of the overcoat layer in this state, and then a slightly thick base is attached to the back side of the magnetic layer. The present invention provides a method for manufacturing a magnetic medium characterized by the following.

[Effect]

In the present invention, instead of applying a magnetic layer to the surface of the base and then attaching an overcoat layer to the surface of the magnetic layer as in the past, the overcoat layer is temporarily held on a flat surface, and the overcoat layer is temporarily held on a flat surface. A magnetic material is applied to the back surface of the overcoat layer while the surface of the layer remains flat. Therefore, even after the magnetic layer is dried, the surface of the overcoat layer is always smoothed, and the unevenness of the magnetic material is absorbed into the surface of the base. Therefore, the surface of the overcoat layer that comes into contact with the magnetic head is always smoothed, eliminating the need for polishing with a grinder or the like after manufacture, and providing extremely good sliding properties of the magnetic head.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows a cross section of a magnetic medium manufactured according to the present invention. On the surface of the base 11 is a pinned layer 12 filled with glue or the like, and on the top surface of the pinned layer 12 is a magnetic material such as strontium ferrite. A magnetic layer 13 containing material is deposited. An extremely thin overcoat layer 14 is formed on the surface of this magnetic layer 13.

Next, the manufacturing method in this example will be explained.

FIG. 3 shows the state at the preliminary stage of the manufacturing process, in which a dummy tape 15 of wall thickness is attached to the back side of the thin overcoat layer 14 made of polyester or the like mentioned above, and the overcoat layer The dummy tape 14 and the dummy tape 15 are supplied together, and are kept in a state where they can be easily peeled off. This overcoat layer 14 and dummy tape 15 constitute a protective tape 16.

Next, FIG. 4 shows the state during the manufacturing process, and the smooth roll 17, which has a slightly large diameter, has been processed to have an extremely flat surface and is rotating in the direction of the arrow in FIG. 4. And the above-mentioned protective tape 1
The protective tape 16 is taken out from one end of the supply roll 18 on which the dummy tape 15 is wrapped, and its back side (with the dummy tape 15 side as the back side) is in close contact with the surface of the smooth roll 17. It is wound up. A nozzle 21 of a hopper 20 is brought close to the surface of the protective tape 16 (toward the overcoat layer 14), and a magnetic material 22 is placed inside the hopper 20.
is stored in liquid form. A slightly thick base 11 made of polyethylene or the like is wound around the base roll 23. This base 11 is in close contact with the smooth roll 17 at a slightly lower surface thereof, and the overcoat layer 14 and the base 1
1 is wound in the direction of a winding roll 25.

In this configuration, the protective tape 16 sequentially drawn out from the supply roll 18 is wound around the outer circumferential surface of the smooth roll 17, and rolls on the outer circumference of the smooth roll 17 while keeping the surface flat. During this rolling, the magnetic material 22 housed in the hopper 20 is sprayed thinly from the nozzle 21 and coated on the surface of the overcoat layer 14. Then, when the base 1 has dried to some extent, it is unwound from the base roll 23.
1 is a magnetic layer 13 formed of a magnetic material 22;
When the two are in close contact and dry, the dummy tape 15 is peeled off from the overcoat layer 14 and the dummy tape 15 and the magnetic tape 24 are separated below the smooth roll 17. Then, the dummy tape 15 is wound up and collected by a collection roll 19, and the magnetic tape 24 formed by the overcoat layer 14, the magnetic material 22, and the base 11 is sequentially wound up by a take-up roll 25. Become. The cross-sectional structure of the wound magnetic tape 24 is as shown in FIG. That is, since the overcoat layer 14 is kept smooth by the smoothing roll 17 while the magnetic material 22 is drying, the unevenness due to the particle size of the magnetic material 22 is not excessively large when the magnetic material 22 is dry. This is because they do not protrude to the upper surface of the coating layer 14 but all protrude in the direction of the fixed layer 12, and all unevenness is absorbed by the fixed layer 12. The reason why the dummy tape 15 is attached to the overcoat layer 14 is that the overcoat layer 14 is an extremely thin film, so if it is brought into contact with the smooth roll 17 in that state, it will expand and contract, resulting in a uniform thickness. This is because the dummy tape 15 is used to supplement the strength of the dummy tape 15.

〔Effect of the invention〕

Since the present invention is configured as described above, contrary to the conventional method, the magnetic material is coated with the overcoat layer kept smooth, dried, and then the base is adhered, so that the surface due to the particle shape of the magnetic material is The unevenness does not protrude to the overcoat layer side, but is absorbed into the base side, and the overcoat layer is kept extremely smooth after manufacturing. Therefore, even if the magnetic head comes into contact with the overcoat layer, wear due to surface roughness is reduced, and long-term use is possible.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the structure of a conventional magnetic medium, Fig. 2 is a sectional view showing the structure of a magnetic medium according to the present invention, Fig. 3 is a sectional view showing the structure of a protective tape in the manufacturing process, and Fig. 4. FIG. 2 is an explanatory diagram showing the manufacturing process. DESCRIPTION OF SYMBOLS 11... Base, 12... Fixed layer, 13... Magnetic layer, 14... Overcoat layer.

Claims (1)

[Claims] 1. A thin overcoat layer is brought into contact with a smooth surface, a magnetic layer is applied to the back side of the overcoat layer in this state, and a slightly thick base is then attached to the back side of the magnetic layer. A method for manufacturing a magnetic medium.