JPS63183615A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain the titled medium having excellent durability by providing a magnetic layer contg. fine powder of Al nitride on a nonmagnetic base. CONSTITUTION:The magnetic layer of the magnetic recording medium formed by providing the magnetic layer on one face of the nonmagnetic base contains the fine powder of the Al nitride. Good magnetic head grindability and the sufficient wear resistance of the magnetic layer are obtd. by using the fine powder of the Al nitride. The Al nitride to be used is preferably fine particles having 1-0.1mum grain size. The effect as a grinding agent is low if the grain size is too small and the good dispersibility is not obtainable if the grain size is conversely larger than >=1mum. The magnetic head grindability and wear resistance equiv. to or better than heretofore are imparted to the magnetic layer with the smaller amt. of the grinding agent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to magnetic recording media such as magnetic tapes and magnetic sheets used in audio/video equipment, computers, and the like.

BACKGROUND OF THE INVENTION Magnetic recording media are increasingly becoming more densely packed year by year. As a result, it is necessary to reduce recording and reproducing losses in the short wavelength region, and measures are being taken to further reduce the gap between the magnetic head and the magnetic recording medium during recording and reproducing. That is, making the surface of the magnetic recording medium highly smooth, making the magnetic powder finer, etc. However, as the surface of the magnetic recording medium becomes highly smooth, the contact area between the magnetic recording medium and the magnetic head increases, and the coefficient of friction increases, resulting in poor running performance and durability compared to conventional magnetic recording media.

In other words, due to contact with the magnetic head, magnetic powder falls off from the magnetic layer and adheres to the magnetic head surface, causing clogging, which greatly impairs recording and playback (for example, still life is extremely shortened). Problems etc. arise. For this reason, in order to strengthen the coating strength of the magnetic layer and to obtain a moderate leaning effect on the magnetic head, it is necessary to
A small amount of abrasive particles such as 2o3, Cr2O3, αF6□03, etc. are added to the magnetic layer.

Problems to be Solved by the Invention In recent years, as magnetic layers of magnetic recording media have become highly smooth and magnetic powder particles have become finer, it has become necessary to ensure good contact between the magnetic layer and the magnetic head and to improve the durability of the magnetic layer. There has been a problem in that it has become increasingly difficult to ensure wear resistance. That is, while it becomes difficult to disperse the magnetic paint due to the fine particles of the magnetic powder,
In order to achieve a highly smooth magnetic layer surface, higher dispersion than before is required. ing. Therefore, in order to easily achieve a highly smooth magnetic layer, it is important to reduce the amount of additives such as abrasives contained in the magnetic paint to facilitate dispersion. In addition, the electromagnetic conversion ability of the magnetic layer,
In particular, in order to increase output, it is desirable to reduce the amount of additives that do not participate in electromagnetic conversion.

An object of the present invention is to use a smaller amount of abrasive than conventional methods to ensure good contact between the magnetic layer and the magnetic head, and also to ensure the wear resistance of the magnetic layer.

Means for Solving the Problems The present invention resides in a magnetic recording medium having a magnetic layer provided on one side of a non-magnetic support, in which the magnetic layer contains fine powder of aluminum nitride.

By using fine powder of aluminum nitride as the working abrasive, good magnetic head polishing properties and sufficient wear resistance of the magnetic layer can be obtained. It is desirable that the aluminum nitride used here be fine particles with a particle size of 1 to 0.1 μm. If the diameter is too small, the effect of the abrasive will be reduced, and conversely, if it is too large (1 μm or more), good dispersion cannot be obtained. By using this fine powder, it is possible to provide the magnetic layer with the same or better abrasiveness and wear resistance with a smaller amount than conventionally used abrasives.

Embodiments An embodiment of the magnetic recording medium of the present invention will be described using a magnetic tape as an example. It should be noted that all values of component ratios stated in the Examples indicate parts by weight.

(Example 1) A magnetic paint was prepared as follows.

CO gold-containing -Fe,,03 magnetic iron oxide powder 100 parts Average particle size Length = 〇, 3 μm Acicularity ratio = 1 oz' 1 Coercive force 6500e Polyurethane resin 16 parts Vinyl chloride-vinyl acetate copolymer 6 parts Nitrocellulose Resin 6 parts aluminum nitride powder
3 parts Average particle size 0.3 μm Lecithin 2 parts Methyl ethyl ketone 100 parts Methyl isobutyl ketone 100 parts Toluene
After mixing and dispersing 100 parts of the above composition in a ball mill for 48 hours, 6 parts of a hardening agent (Coronate L) was added, and the resulting mixture was filtered through a filter having an average particle size of 3 μm to prepare a magnetic coating liquid. .

Next, the magnetic paint was applied onto a 15 μm thick polyester film, oriented and dried, and then the magnetic layer was surface-treated using a super calender roll. This was cut into 1/2 inch width to produce a videotape.

(Example 2) A videotape was produced in the same manner as in Example 1 except that 6 parts of aluminum nitride was used as the abrasive in the magnetic paint of Example 1.

(Comparative Example 1) A videotape was produced in the same manner as in Example 1 except that in the magnetic paint of Example 1, 3 parts of aluminum oxide having an average particle size of 0.3 μm was used as an abrasive.

(Comparative Example 2) A videotape was produced in the same manner as in Example 1 except that in the magnetic paint of Example 1, 5 parts of aluminum oxide having an average particle size of 0.3 μm was used as the abrasive.

(Comparative Example 3) In the magnetic paint of Example 1, the particle size of the abrasive was 0.
A videotape was prepared in the same manner as in Example 1 except that three parts of 3 μm chromium oxide (Cr 203) were used.

(Comparative Example 4) In the magnetic paint of Example 1, the particle size of the abrasive was 0.
Using 6 parts of 3 μm chromium oxide (Or 205 ),
A videotape was produced in the same manner as in Example 1 except for the above.

(Comparative Example 6) A videotape was produced in the same manner as in Example 1 except that no abrasive was used in the magnetic paint of Example 1.

The scratch resistance, stealth life, and video S/N of the magnetic layer of each sample thus prepared are shown in the attached table. In this table, (1) Scratch resistance is determined by applying a load of 4 Or to a 6φ steel ball and reciprocating it on the sample tape surface 50 times on the same track at a speed of 20 mm/sec. They were observed and evaluated on a 6-level scale. 1 is the most severely damaged;
6 is the least damaged.

(2) The still life is 50f using a VH5 type VTR.
The measurement was performed with a tension of i' applied.

(3) Video S/N uses a VH3 system VTR, and T
A specified luminance signal (SO% white level signal) from the V signal generator is recorded at the optimum recording current on the reference tape, and the ratio of the signal to noise contained in the demodulated signal during playback is measured using a video color noise meter. This is a comparison with that of tape as ○dB.

As is clear from the above table, the magnetic tape obtained in the above manner has excellent wear resistance even with a smaller amount of abrasive compared to conventional products, and the contact condition with the magnetic head is It has good electromagnetic conversion characteristics. Although this example describes a magnetic tape, it goes without saying that the present invention can be applied not only to magnetic tapes but also to other magnetic recording media such as magnetic sheets.

Effects of the Invention As detailed above, according to the present invention, it is possible to obtain a magnetic recording medium having a magnetic layer that has excellent abrasion resistance and polishes the magnetic head to an appropriate degree, so its practical value is extremely high. There is something.

Claims (1)

[Claims] A magnetic recording medium characterized in that a magnetic layer containing fine powder of aluminum nitride is provided on a nonmagnetic support.