JPH0246524A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve durability of the magnetic layer without degrading the electromagnetic conversion characteristic as small as possibly by incorporating a powder of titanium boride or zirconium nitride as an additive into the mag netic layer. CONSTITUTION:The titanium boride (TiB2) powder or zirconium nitride (ZrN) powder is incorporated as a nonmagnetic additive into the magnetic layer. Titanium boride powder is produced from high-temperature direct reaction of metal titanium and boron, and so is zirconium nitride powder from metal zirconium and nitrogen. Both compounds are intrusion-type, the particles of which are found polygonal by microscopy. As the powder consists of polygonal particles, it has a proper polishing property, which can maintain a clean surface of a magnetic head and avoids degradation of reproduction output due to head clogging. Thereby, durability of the magnetic layer can be improved without degrading, as small as possible, the electromagnetic conversion characteristics of magnetic recording medium such as a magnetic tape, floppy disk, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic recording media such as magnetic tapes and floppy disks used in audio equipment, video equipment, computer equipment, and the like.

[Summary of the invention]

The present invention provides magnetic recording media such as magnetic tapes and floppy disks used in audio equipment, video equipment, computer equipment, etc., by incorporating titanium boride or zirconium nitride powder as an additive into the magnetic layer. The purpose is to improve the durability of the magnetic layer without reducing the conversion characteristics as much as possible.

[Conventional technology]

In recent years, in order to meet the increasing demand for high-density recording in magnetic recording technology, the surface of magnetic recording media such as magnetic tapes and floppy disks has been processed to have an ultra-smooth surface using a supercalender to reduce spacing loss. There is. In addition, based on the same request, efforts have been made to improve magnetic properties by making magnetic powder particles finer and changing from oxide-based magnetic materials to metal-based magnetic materials with lower hardness.

On the other hand, on the magnetic head side as well, the track width is narrowed to about 10 μm to achieve high density recording by efficiently utilizing the area of the magnetic recording medium.

Furthermore, the relative speed between the magnetic recording medium and the magnetic head exceeds 1 meter per second, not only in video tape recorders but also in audio tape recorders, as recent digital audio tape recorders (DATs) employ rotating head mechanisms. Efforts are being made to speed up the process.

In response to these high-density recordings, the surface of the magnetic layer of a magnetic recording medium is easily damaged, which reduces durability, and on the magnetic head side, this is caused by deposits on the track surface. The head crawling phenomenon causes a reduction in the playback output level.

It is thought that the deposits on the track surface are mainly deposits from damaged parts of the magnetic layer surface.

Therefore, in order to improve durability, α was added to the magnetic layer in order to improve durability.
- Contain 10 parts by weight or less of non-magnetic additives with high hardness such as alumina (Japanese Unexamined Patent Publication No. 60-177432) and nichrome trioxide (Japanese Unexamined Patent Publication No. 60-209925) based on 100 parts by weight of magnetic powder. has been carried out. Furthermore, it has been proposed to contain 1 to 10 parts by weight of at least one of titanium carbide, titanium nitride, silicon nitride, and tungsten carbide in the magnetic layer based on 100 parts by weight of magnetic powder (Japanese Unexamined Patent Application Publication No. 1983-1992-1). 212820).

However, even with these conventional techniques, it has not been possible to improve durability in still mode without deteriorating electromagnetic conversion characteristics such as reproduction output level. In other words, if the content of non-magnetic additives is small, the electromagnetic conversion characteristics are excellent but the durability is poor; on the other hand, if the content of non-magnetic additives is increased, the durability is improved but the electromagnetic characteristics are poor. It was not possible to satisfy the conversion characteristics.

[Problem to be solved by the invention]

In view of these problems, the problem to be solved by the present invention is to improve the durability of the magnetic layer in magnetic recording media such as magnetic tapes and floppy disks without impairing good electromagnetic conversion characteristics as much as possible. The purpose is to

[Means to solve the problem]

In order to solve the above-mentioned problems, the magnetic recording medium according to the present invention contains titanium boride (titanium boride) as a non-magnetic additive in the magnetic layer.
TiBz) powder or zirconium nitride (ZrN) powder.

Titanium boride powder is an interstitial compound obtained by direct high-temperature reaction between metallic titanium and boron, and zirconium nitride powder is obtained by direct high-temperature reaction between metallic zirconium and nitrogen. When observed using an electron microscope, both particles have a polygonal appearance. It is showing. This is unique compared to the approximately spherical particle shapes of α-alumina and nichrome trioxide, which are non-magnetic additives that have been used in the past but have not been sufficiently effective.

[Effect]

These non-magnetic additives used in the present invention have a Vickers hardness of 1600 to 3400 kg/m as shown in Table 1.
Since it is large (m2) and has a polygonal particle shape, it has an appropriate abrasive action, and has the effect of keeping the magnetic head surface always clean and avoiding a reduction in reproduction output due to the head crawling phenomenon.

In addition, by uniformly dispersing these non-magnetic additives in the magnetic layer, the non-magnetic additives exert a reinforcing effect on the magnetic layer coating, and the magnetic properties that tend to occur when sliding on a magnetic head, drum, tape guide, etc. It has the effect of preventing scratches on the surface of the layer. All of these effects enable long-time playback in still mode and work toward improving the durability of the magnetic recording medium.

〔Example〕

The present invention will be described below based on Examples and Comparative Examples.

fruit 11tsu 1 First, a magnetic paint was prepared with the following composition.

Go-containing 7-Fe, 03------------
------100 parts by weight (specific surface area 45 m2/g) Vinyl chloride-vinyl acetate-vinyl alcohol copolymer resin--------
--42 parts by weight (S-LEC A, manufactured by Block Chemical Industry Co., Ltd.) Polyurethane resin ---111--
-----8 parts by weight (N-2 manufactured by Nippon Polyurethane Industries)
304) Carbon black ------------------------
2.5 parts by weight (Conductex SC manufactured by Columbian Carhon) Butyl stearate
−−−−−−−−−−−−−−−−−−2, 5 parts by weight methyl ethyl ketone −−−−−−−−−−−−−−−−
----120 parts by weight Methyl isobutyl ketone---
−−−−−−−−−−−−60 parts by weight of toluene−−−
−−−−−−−−−−−−−−−−−−−−−−−−
-------------60 parts by weight 10 parts by weight of titanium boride powder with an average particle size of 0.5 μm was added as an additive to the above composition, and after mixing and dispersing in a ball mill for 48 hours, a curing agent was added. 3 parts by weight of isocyanate (Coronate, manufactured by Nippon Polyurethane Industries) was added and mixed, and the mixture was filtered through a filter to obtain a magnetic paint.

Next, the above magnetic paint was applied onto a polyethylene terephthalate film having a thickness of 14 μm and dried, and the magnetic layer was subjected to ultra-smooth surface processing by supercalendering, and then hardened to obtain a jumbo roll.

The thickness of the magnetic layer was set to 6 μm.

The jumbo roll was cut into A-inch width and loaded into a video cassette case to form a sample tape.

Additive used in Example 1 with an average particle size of 0.5μ
m titanium boride powder was used as it was, and the content was adjusted to 0.5
．． Four types of sample tapes were prepared in the same manner as in Example 1 except that the amount was 1.5 or 25 parts by weight.

Fruit 1 Vice Runi 1 Two types of titanium boride powder were prepared in the same manner as in Example 1, except that the average particle size of the titanium boride powder as an additive was selected to be 0.1 or 1.0 μm, and the contents were both 10 parts by weight. A sample tape was created.

Example 1 Part 12 Zirconium nitride powder was used in place of the titanium boride powder used as the additive in Examples 1 to 7. The average particle size is all 0.4μm, and the content is 1.2.10.2
0 or 40 parts by weight.

Other than that, five types of sample tapes were prepared in the same manner as described in Example 1.

Disaster Flame■2■ The average particle size of zirconium nitride powder as an additive is 0.
Two types of sample tapes were prepared in the same manner as in Example 1, except that the sample tapes were selected to have a diameter of 1 or 0.9 μm, and the contents were both 10 parts by weight.

In this comparative example, dichromium trioxide, which has been conventionally used as an additive, was used, the average particle size was 0.4 μm, and the content was 5.10, or 20 parts by weight. Three types of sample tapes were prepared in the same manner as in Example 1 except for the additives.

In this comparative example, nichrome trioxide, which has been conventionally used as an additive, was used, and the average particle size was 0.6 or 0.8 μm.
The contents were both 10 parts by weight. Two types of sample tapes were prepared in the same manner as in Example 1 except for the additives.

Comparison 21 In this comparative example, α-alumina, which has been conventionally used as an additive, was used, the average particle size was 0.4 or 0.6 μm, and the content was 10 parts by weight. Example 1 except for additives
Two types of sample tapes were created in the same manner.

By the method explained above, sample tapes according to 14 types of examples according to the present invention and sample tapes according to 7 types of comparative examples were created. These are shown in Tables 2 and 3 together with the measurement and evaluation results using a home video tape recorder.

Below are the margins of Table 2, Table 3. Furthermore, for the purpose of improving the durability of the magnetic layer, there is a lower limit for the content of non-magnetic additives, and for titanium boride per 100 parts by weight of magnetic powder, it is 0.
5 parts by weight, and 1 part by weight for zirconium nitride.

In this example, Co-containing 7-F was used as the magnetic powder.
Although e2O2 was used, 7-Fe2O3, Fe3O4
It is possible to use ferromagnetic powders having an isospinel structure, barium ferrite powders having a magnetoblumbite structure, chromium dioxide powders, metal-based powders, and the like. Further, as the binder, in addition to the vinyl resin and polyurethane resin used in this example, polyester resin, nitrocellulose resin, polyacecool resin, polyvinyl butyral resin, etc. may be used.

〔Effect of the invention〕

As described in detail above, according to the present invention, the effect of preventing scratches on the surface of the magnetic layer by reinforcing the magnetic layer coating film and keeping the track surface of the magnetic head always clean are as shown in Tables 2 and 3 above.
In the table, the content of the additive is expressed in parts by weight of the additive based on 100 parts by weight of the magnetic powder. In addition, the playback output was shown by recording a 4.5 MHz test signal on a sample tape and comparing the playback output with the playback output of a standard tape. Still characteristics were expressed by recording a test signal of 4.2 MHz on a sample tape, continuously reproducing the same track on the magnetic tape in still mode, and expressing the time until the reproduction output attenuated to 50% of the initial reproduction output.

Comparative Examples 1 to 7 in Table 3 failed to satisfy both the reproduction output of 068 or more and the still characteristics of 120 minutes or more, whereas in Examples 1 to 14 according to the present invention in Table 2, all samples Tape playback output 06
8 or more and still characteristics of 120 minutes or more.

As is clear from this example, the content of non-magnetic additives is limited by a certain upper limit when considering electromagnetic conversion characteristics, especially reproduction output characteristics, and in titanium boride powder per 100 parts by weight of magnetic powder. Polishing properties suitable for both 25 parts by weight and 400 parts by weight for zirconium nitride powder are achieved, and a magnetic recording medium with excellent durability can be obtained without deteriorating the electromagnetic conversion characteristics as much as possible. The utility value of the above is great.

Claims (1)

[Claims] A magnetic recording medium comprising a magnetic layer mainly composed of magnetic powder and a binder formed on a non-magnetic support, characterized in that the magnetic layer contains titanium boride powder or zirconium nitride powder. recoding media.