JPH0349024A - magnetic recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention secures the necessary output and C/N for use in video/audio equipment that requires high-density recording in the submicron region, and The present invention relates to a low-cost magnetic recording medium that is highly mass-producible.

BACKGROUND OF THE INVENTION Magnetic recording has traditionally been developed using a longitudinal magnetic recording method that uses in-plane magnetization of a magnetic recording medium. Most of the magnetic tapes currently in use use this longitudinal recording method.

At present, magnetic materials such as acicular iron oxide and metal are mainstream as the magnetic materials that make up the media.Also, alumina is used to increase coating strength and polish the magnetic head, and to lower electrical resistance and improve runnability. Carbon is added to improve running performance and lubricant is added to improve runnability and durability, and these materials are uniformly dispersed in an organic binder to obtain a magnetic film.

Generally, in longitudinal recording, in order to increase the output, it is required that the magnetic powder in the coating film be oriented in the head-medium running direction. In the longitudinal recording method, the greater the degree of longitudinal orientation of the magnetic powder in the coating film, the greater the C/N during high-density recording, so the prior disclosed technology attempts to increase the longitudinal opening. For example, JP-A-62-172533
No. 1, JP-A-62-219332, JP-A-62
-298927.

However, it is known that the longitudinal recording method must overcome self-demagnetization loss during high-density recording, and therefore increasing the coercive force of the medium is an essential condition for high-density recording. However, it is technically difficult to achieve a higher coercive force than the current acicular iron oxide and metal magnetic powders.
Currently, there are also problems with heads that can adequately write on high coercive force media.

There is also a method of producing a metal thin film continuous medium as a method for further increasing the magnetic properties and effectively securing the output and C/N compared to the metal powder coated medium. In this method, it is advantageous in manufacturing to reduce the film thickness, and this is effective in reducing self-Ml loss due to the demagnetizing field.

Furthermore, it is well known that perpendicular magnetic recording has been proposed as a method to solve the problems of longitudinal recording.

For example, the literature includes Nakamoto, Nakamura, and Iwasaki, Journal of the Japanese Society of Applied Magnetics, Vol. 11 (1987) P2O3-114.

In perpendicular recording, the higher the recording density, the lower the self-tJ&
Magnetic loss is reduced, and practical research is being conducted in various places as the ultimate magnetic recording method. Prior art disclosures include Japanese Unexamined Patent Publication No. 132183/1983.

There is also a technical report that uses hexagonal plate-shaped barium ferrite magnetic powder and applies it to a perpendicular recording system.

For example, JP-A-60-211628, JP-A-60
-209928, JP 60-212817, JP 61-230621, JP 62-6
There is a publication No. 01222.

Problems to be Solved by the Invention According to the techniques disclosed in these documents, the output in the short wavelength range shows considerable characteristics compared to conventional coated recording media, but the saturation magnetization of the magnetic powder used is Value is 50-58
emu/g and about 120elIu/gS of metal powder
Currently, the output and C/N are somewhat unsatisfactory because the output and C/N are smaller than the approximately 70 emu/g of acicular iron oxide coated with CO.

Means for Solving the Problems In order to solve the above problems, the magnetic recording medium of the present invention includes:
When the lattice image of magnetic powder was observed by electron diffraction, 2
This is a magnetic recording medium using a magnetic powder characterized in that the lattice image of the 8 if powder has a magnetoplumbite structure and an excess spinel structure.

Effect The present invention effectively increases the saturation magnetization value of the magnetic powder with the above-described configuration, and as a result, the magnetic properties of the recording medium are improved, and the output/C/N of the tM1 conversion characteristic is improved. .

EXAMPLE A magnetic recording medium according to an example of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic explanatory diagram for explaining a photograph of a lattice image of magnetic powder used in an example of the present invention. In Figure 1, l is the R phase containing barium atoms and the spinel phase (S phase) that constitutes a magnetoplumbite structure.
2 represents a lattice image due to the overlapping spinel phase. The above magnetic powder was used as a magnetic recording medium in an example. The average particle diameter and average plate thickness of the magnetic powder are shown as the average value of 100 particles taken from a transmission electron microscope photograph.

The following components were prepared as a paint composition, and after hardening and dispersing using a pressure kneader, the mixture was mixed and dispersed using a sand mill to prepare a magnetic paint.

・Magnetic powder containing barium atoms (plate diameter 0.07μm, plate thickness 0.02μm, coercive force 90
00e, saturation magnetization 67 emu/g) Vinyl chloride polymer Polyurethane Carbon Alumina Lubricant Solvent Toluene IBK Cyclohexanone 200 parts 15 parts 15 parts 4 parts 8 parts 2 parts 180 parts 180 parts 30 parts, hardening agent 12
After filtering the obtained paint, it was coated using a blade coater with a distance between the blade and the substrate surface of 35 μm. A polyethylene terephthalate film with a thickness of 14 μm was used as the base. After the coating film dries, it is calendered (80%
135 kg/cta) to smooth the surface of the recording medium, and then harden for 30 hours. The thus obtained magnetic recording medium was cut into pieces of 1/2 inch and used as examples.

Next, a comparative example will be explained.

FIG. 2 is a schematic explanatory diagram of a lattice image of the magnetic powder used in the comparative example obtained by an electron microscope. In FIG. 2, ■ represents a lattice image resulting from a layered structure of an R phase containing barium atoms and a spinel phase (S phase) constituting a magnetoplumbite structure, as in FIG. 1. The lattice image of the excess spinel phase seen in FIG. 1 is not present. Regarding the coating composition and tape formation using this magnetic powder, samples were prepared in the same manner as in the examples and used as comparative examples. The data of the magnetic powder used in the comparative example is shown below.

- Magnetic powder containing barium atoms (plate diameter 0.07 pm, plate thickness 0.02 µm, coercive force 9000e, saturation magnetization 57 emu/g) Examples and comparative examples were evaluated as follows.

Magnetic properties were measured using a Toei Kogyo vibrating sample magnetometer with a maximum magnetic field of 10 KOe and a sweep speed of 3 minutes/10 KOe.
It was measured with In addition, as a measure of the surface roughness of the medium, the glossiness was measured using a digital glossmeter manufactured by Nippon Shinshoku Kogyo (45 degrees - 45 degrees).

! The magnetic conversion characteristics are a tape rotating drum with a drum diameter of 80 mm,
Measurement was performed using a drum tester with an internal magnetic head. The relative speed was 3.1 m/sec, and the magnetic head used was a metal-in-gap type with a gap length of 0.3 μm, a track width of 23 μm, a number of windings of 24 turns, and a gap depth of 15 μm. The measurement frequency is 130 to 7, 4.7
It is M7.

These results are summarized in Table 1. The output shows the value at the optimum recording current, and is shown as a relative value based on the output of the comparative example. 2 represents the longitudinal direction of the medium, and the top represents the thickness direction of the medium. B.M., Br.

Sr and Hc represent the saturation magnetic flux density, residual magnetic flux density, squareness ratio (Br, Bm), and coercive force, respectively.

As is clear from Table 1, the magnetic recording medium of the present invention has an EI when the lattice image of the magnetic powder is observed by electron beam diffraction.
By using a magnetic powder whose En magnetic powder lattice image has a mag2 de brambite structure and an excess spinel structure, the magnetic properties and electromagnetic conversion properties can be further improved.

In the embodiment of the present invention, a magnetic tape is used, but it goes without saying that the same effect can be applied to a magnetic disk.

Margin Table 1 Table 1 Effects of the Invention As described above, in the magnetic recording medium of the present invention, when the lattice image of the magnetic powder used is observed by electron beam diffraction, the lattice image of the magnetic powder has a magnetoplumbite structure. Furthermore, by using magnetic powder characterized by having an excessive spinel structure, magnetic properties and electromagnetic conversion properties can be improved.

The magnetic recording medium of the present invention can be used for low-cost, large-capacity, and highly reliable information recording, and can be used for audio and other applications.
It is a useful invention that greatly contributes to improving the performance of video equipment and memory equipment.

[Brief explanation of drawings]

Figure 1 is a schematic illustration of a lattice image observed by electron beam diffraction of the magnetic powder used in the magnetic recording medium of the example of the present invention, and Figure 2 is the electron beam of the magnetic powder used in the magnetic recording medium of the comparative example. FIG. 2 is a schematic explanatory diagram of a lattice image observed by a line diffraction method. 1... R phase containing barium atoms, S phase with magnetoplumbite type structure, and lattice image due to stacked structure, 2...
...Lattice image due to excessive spinel structure.

Claims (2)

[Claims] (1) A magnetic recording medium obtained by kneading magnetic powder and an additive/organic binder to prepare a magnetic paint, and then applying the paint onto a non-magnetic substrate, in which a lattice image of the magnetic powder is electronically generated. When observed by a line diffraction method, the lattice image of the magnetic powder has a lattice image from a laminated structure of S blocks and R blocks having a magnetoplumbite type structure and, in addition, a lattice image from an excess spinel block. magnetic recording media. (2) The magnetic recording medium according to claim (1), wherein the magnetic powder contains at least barium atoms, iron atoms, and oxygen atoms.