JPS60620A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium which is free from uneven orientation and has a good vertical magnetic characteristic by drying once a magnetic medium prior before the medium enters a magnetic field for orientation and dissolving the surface layer again with the vapor of a good solvent for the resin binder contained in the magnetic coated film then orienting the same in the magnetic field. CONSTITUTION:A Ba-Fe coated film 3 is formed on a polyethylene terephthalate film 1 having 15mum thick by a reverse roll coater 3 so as to have 2.5mum film thickness after drying and is once dried in the 1st drying zone 4 then the film is redissolved by vapor 5' of methyl ethyl ketone 5 and is oriented between vertical magnetic fields 6 and 6' and at the same time the film is dried by hot air 7 until at least the oriented particles are made immobile. The film is thoroughly dried in a drying zone 8. However, the film is not always required to be thoroughly dried in 1st drying zone 4 and may be dried to the extent that the particles cannot move in the fields 6, 6'.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] Generally used audio and video magnetic recording media have their magnetic properties improved.

B. The eutectic fine particles are oriented, and the present invention improves such an orientation method, and is a method particularly suitable for manufacturing high-density magnetic recording media that maintains perpendicular orientation.

[Technical background of the invention and its problems]

Magnetic recording media such as magnetic tape and magnetic tape are usually produced by coating a non-magnetic substrate such as a polyethylene terephthalate (PET) film with a paint in which magnetic powder is dispersed in a resin binder. Or dry.

Used after surface treatment and cutting. However, during the above-mentioned magnetic field orientation, r-crossing, and drying, considerable agglomeration occurs, so that the subsequent surface treatment with a calender becomes a tedious process. In particular, in the case of vertically oriented magnetic recording materials, drying in a magnetic field is not an effective method in order to prevent magnetic agglomeration. However, due to rapid drying, surface roughness is likely to occur due to drying. 1. This may cause the change/color to be blank. was.

[Go to 6 purpose] Motoichi 1i,! 4 is a coated magnetic recording medium that maintains substantial characteristics and improves 1 to 1, j-1, mil notation, and 'j. I+, Juroi, Nono.

[Invention book required]

In order to perform high-density recording, the recording wavelength must also be at a high frequency (
For example, 4MHz) is required. In this F high frequency region, the depth of the signal extracted from the 01 layer is approximately 1.5μ.
It has been experimentally determined that the temperature is m8 degrees. Therefore, the thickness of the magnetic film should be 1.5 μm. However, as a practical matter, in the case of coated magnetic media, no matter how advanced the centering device is used, coating unevenness will occur, so it seems that the coating is thicker than necessary.

As mentioned above, in the case of vertical alignment, drying in a magnetic field is currently unavoidable, and the above-mentioned coating unevenness becomes drying unevenness, which causes alignment unevenness.

゛The present invention is intended to improve the above-mentioned drawbacks.

That is, for example, the thickness of the magnetic paint after drying is 2.5 μm.
Apply it so that it looks like this, and once it dries, apply it again? J￥) Chinese good solvents (methyl ethyl ketone, acetone.

cyclohegisanone, methyl-in-butylketone, tetrahydrofuran, dimethylpormamide, etc.), the particles of 1.5 to 2.0 μm are redissolved and then oriented in a magnetic field, followed by drying at the same time. . According to this method, steam penetrates through the surface of the paint film during remelting.

Since the thickness of the dissolved layer is all uniform, i"i"
There is no uneven orientation in the F hi'i part, and there is a high orientation of 1.
'The high 111 force is (5)C. But f>,'lt
For example, when looking at the circular ratio as an A characteristic, it cannot necessarily be said to be good because of the presence of a non-oriented layer, but the practical characteristic is, for example, a hexagonal flat plate-shaped L with an abrasive valley axis in the 14 orthogonal direction. (
In the case of the a-JI''e system, the properties were significantly improved, and the properties were better than those of metal tape.The surface properties of the coating film after drying were also improved by re-dissolving the film, and the viscosity of the film was 1 ton). ] Significant improvement over the conventional method. According to the method of the present invention, the same effect can be achieved not only in the case of vertical alignment but also in the case of in-plane alignment.
I) be received.

[Embodiments of the invention]

In this example, a 13a-Fe (average grain size: 0.08 μm) coating film on a titanized 6ITI flat plate was used for high-density magnetic recording.

Trouble! (The vertical orientation will be explained according to No. 11\I.

A Ba-1i'e coating film (3) was formed on the ethylene terephthalate film (1) with a thickness of 15 μm using a reverse roll coater (3) so that the film thickness after drying was 2.5 μm. 1 drying zone (4), then methyl-ethyl-ketone (5) vapor (5')
The particles are redissolved and oriented between vertical magnetic fields (6') and (6'), and at the same time the particles that have been oriented at least by warm air (7) are dried until no 'J' is left, and completely dried by the drying zone (8). Let dry. Tasoshi.

The degree of dryness in the first drying/drying zone (4) does not necessarily have to be completely controlled by the magnetic field t'6), (6'
) as long as the particles cannot move inside.

Table 1 shows the results of measuring the rhombus: i:jt satobe 1 garden air characteristics before and after calendering using the sample. still,
As comparative examples, one does not use Mu 1, 1 drying (4) and rebath 1/sweat zone (5), (5'), and the other uses only the first dry zone (4) and uses metal tape. Using.

, hereinafter f: mortar Table 1 *Magnetic properties are values measured at a relative speed of 3.5 m/sec.

**Do not re-dissolve.

Surface properties according to the method of the present invention as shown in Table 1.

V with excellent filter characteristics! In particular, results far superior to those of metal tape were obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the steps of the method of the present invention.

Claims (1)

[Scope of Claims] In the production of a coated magnetic recording medium in which a magnetic material made of fine particle powder is applied and oriented with a coating material dispersed together with a resin binder on a non-magnetic substrate, the magnetic Orient the medium before entering the magnetic field. Once dried, the surface layer is again dissolved with vapor of a good solvent for the resin binder contained in the magnetic coating film, and then oriented in a magnetic field, and then dried in the magnetic field. A method for manufacturing a recording medium.