JPH02260237A - Orientation device for magnetic layer - Google Patents

Abstract

PURPOSE:To effectively execute the orientation of a magnetic medium having a magnetic layer whose BET value is >=40m<2>/g by determining the magnetic field intensity of oppositely orientated magnets to >=800 gausses and selecting a magnet having magnetic field intensity determined by the traveling speed of a magnetic medium. CONSTITUTION:The magnetic field intensity of the oppositely orientated magnets arranged oppositely to each other through the magnetic medium having the magnetic layer whose BET value is >=40m<2>/g and traveling at a traveling speed (v) is >=800 gausses and the effective length of the intensity satisfies the shown inequality. Thus, a magnetic body having the high quality magnetic layer containing magnetic powder whose surface area is extremely large and being capable of executing high density recording can be orientated without using the large quantity of power. When the traveling speed of the magnetic medium is 100m/min, preferablly 150m/min, the magnetic layer can be especially efficiently orientated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic layer orientation device, and more particularly to a magnetic layer orientation device that can achieve a high degree of orientation with high productivity. Regarding.

[Prior art and problems to be solved by the invention] Magnetic recording media are manufactured by coating a magnetic layer on a support and then orienting the ferromagnetic powder in the magnetic layer in a certain direction. There is.

Conventionally, a support with a magnetic layer is run through an electromagnet formed by a single energized coil, or a support with a magnetic layer is run between a pair of oppositely oriented magnets with the same polarity facing each other. The ferromagnetic powder in the magnetic material is oriented by this method.

However, in recent years, in order to highly orient a magnetic material having a high-quality magnetic layer containing magnetic powder with an extremely large surface area and capable of high-density recording, the method using the electromagnet requires a large amount of electric power. There is a problem with using it.

Furthermore, since extremely large electromagnets must be placed, there is also the problem that a large area must be secured.

This invention aims to solve the above problems.

That is, the present invention provides a method for orienting a magnetic layer that can orient a magnetic material having a high-quality magnetic layer with high-density recording rotation that contains magnetic powder with an extremely large surface area without using a large amount of electric power. It is a device.

[Means for solving the above problem] This invention for solving the above problem has a BET value of 40
m'/g or more and has a magnetic medium running at a traveling speed of V, the magnetic field strength of the counter-oriented magnets arranged opposite to each other is 800 Gauss or more, and the magnetic field strength is 800 Gauss or more. This is a magnetic layer orientation device characterized in that the effective length satisfies the following formula.

L≧(215,000) A magnetic medium having a magnetic layer with a BET value of 40 m2/g or more by determining the magnetic field strength of the oppositely oriented magnets to be 800 Gauss or more and selecting a magnet with a magnetic field strength determined by the traveling speed of the magnetic medium. can be effectively oriented.

Furthermore, once the effective magnetic field length of the oppositely oriented magnets having a magnetic field strength of 800 Gauss or more is determined, the traveling speed of the magnetic medium that is caused to travel between the magnetic field strengths is also determined.

In the present invention, the magnetic layer can be oriented particularly efficiently when the traveling speed of the magnetic medium is 100 m/min, preferably 150 m/min.

[Example 1 (Example 1) A web 2 formed by applying a magnetic paint having the composition shown below to polyethylene terephthalate as an indicator was run between the N-N opposing orientation magnets 1 shown in FIG. The magnetic layer was oriented.

Composition of magnetic paint Cobalt-containing magnetic iron oxide 150 parts by weight Polyurethane 10 parts by weight Vinyl chloride copolymer 20 parts by weight α-alumina
lO East Part I Myristic Acid Double Sewing Part Olein #0.5 parts by weight Butyl Stearate 1 Electrical Sewing Part Polyisocyanate 10 Double Sewing Part Toluene
200@parts Methyl ethyl ketone 20
0 @m? B Carbon black 10 @ Keibu At this time, the magnetic field strength of magnet l is 800 Gauss or more, maximum 2. The BET value of the ferromagnetic powder in the magnetic layer was 45 m2/g, and the traveling speed of the magnetic medium was 150 m/min.

From this condition, the effective length L of the oppositely oriented magnets having the field strength I was (1.06 m).

Table 1 shows the results of evaluation of this magnetic layer according to conventional methods.

(Example 2) Except that the running speed of the web 2 was 300 m/min (from this condition, the effective length L having the m#A strength of the oppositely oriented magnets was 0.12 m), the above Example 1 It was carried out in the same way. The results are shown in Table 1.

(Comparative Example 1) The effective inversion L having the magnetic field strength of the oppositely oriented magnets is set to 0.
The same procedure as in Example 1 was carried out except that the sample was changed to 03. The results are shown in Table 1.

(Comparative Example 2) Except for setting the magnetic field strength of the oppositely oriented magnets to 700 Gauss, the rf
It was carried out in the same manner as in Example 1 of iJ. The results are shown in Table 1.

Table 1

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention.・N-N opposing orientation magnet, 2. ・Magnetic medium.

Claims (1)

[Claims] (1) A magnetic medium having a magnetic layer with a BET value of 40 m^2/g or more and traveling at a traveling speed v is placed inside,
The magnetic field strength of the oppositely oriented magnets is 800
A magnetic layer alignment device characterized in that the magnetic field strength is Gauss or higher and the effective length of the magnetic field satisfies the following formula. L≧(2/5,000)×v [However, L is the effective length (
m), v is the running speed (m/min) of the magnetic medium. ]