JPS61920A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the wear resistance of a magnetic layer without the wear of a magnetic head and the decrease in the electromagnetic converting characteristic of said layer by incorporating Si3N4 powder into the magnetic layer. CONSTITUTION:A magnetic paint contg. magnetic powder, binder and the Si3N4 powder as non-magnetic powder is prepd. and is coated on a substrate to form the magnetic layer. The Si3N4 having 0.1-1.5mum, more preferably 0.3-1.0mum average particle size is preferably. The effect of improving the wear resistance is not enough if the particle size is too small. The surface smoothness and eventually the electromagnetic converting characteristic are lower and there is less effect of suppressing the wear of a magnetic head if the particle size is too large. Both cases are undesirable.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to magnetic recording media such as magnetic tape.

[Background Art] Magnetic recording media such as magnetic tapes, which are formed by providing a magnetic layer containing magnetic powder and its binder on a substrate such as a polyester film, come into violent sliding contact with a magnetic head during recording and reproduction. It is strongly desired that the magnetic layer undergoes less wear due to the wear of the magnetic layer, that is, the magnetic layer has excellent wear resistance.

For this reason, conventional efforts have been made to improve the wear resistance of the magnetic layer by including a relatively hard non-magnetic powder in the magnetic layer. The above non-magnetic powder includes k120s powder, Cr2O3
powder, TlO2 powder, etc. are known, but although these can achieve good results in wear resistance, they have the problem of abrading the magnetic head, and also have poor dispersibility in the magnetic layer, causing damage to the surface of the magnetic layer. There was a problem in that the electromagnetic conversion characteristics deteriorated due to a decrease in smoothness.

It is also known to use non-magnetic powder with a large particle size that is not very hard, such as α-Fe203 powder, and although this non-magnetic powder does not have the above-mentioned problems,
On the other hand, the wear resistance of the magnetic layer could not be improved much, and if one tried to compensate for this by increasing the amount used, there was a problem that the amount of magnetic powder in the magnetic layer would be relatively reduced and the electromagnetic conversion characteristics would be impaired. .

[Objective of the Invention] The present invention aims to solve the above-mentioned conventional problems, that is, to provide a magnetic non-recording medium that can improve the wear resistance of the magnetic layer without causing wear of the magnetic head or deterioration of electromagnetic conversion characteristics. The purpose is to

[Summary of the invention]

As a result of intensive studies to achieve the above object, the inventors found that when non-magnetic powder made of Si3N powder was included in the magnetic layer, magnetic properties could be achieved without causing wear of the magnetic head or deterioration of electromagnetic conversion characteristics. It was discovered that the wear resistance of the layer could be greatly improved, and this invention was completed.

That is, the present invention provides a magnetic recording medium comprising a magnetic layer containing non-magnetic powder and a binder thereof on a substrate, characterized in that the magnetic layer contains Si3N4 powder. This is related.

The 5i3N1 powder used in this invention is
It has a hardness comparable to that of 2O3 powder (Mohs hardness: 9), has good dispersibility in the magnetic layer probably due to its granular shape, and is extremely stable both chemically and thermally. It has the property of being. Therefore, the abrasion resistance of the magnetic layer can be greatly improved with a small amount used, and there is no problem of deterioration of the surface smoothness of the magnetic layer and the accompanying deterioration of the electromagnetic conversion characteristics. Good results can also be obtained in suppression.

The average particle size of this Si3N4 powder is 0.
1 to 1.5) m, preferably 0.3 to 10 voices. If the particle size becomes too small, the effect of improving wear resistance will not be sufficiently achieved, and if it becomes too large, the surface smoothness and associated electromagnetic conversion characteristics will deteriorate, and the wear suppression effect of the magnetic head will decrease. Therefore, both are unfavorable.

The amount of Si3N powder to be used is usually 03 to 15 parts by weight, preferably 0.5 to 1 part by weight, per 100 parts by weight of magnetic powder.
It is preferable to set it to 0 parts by weight. If too much is used, the content of magnetic powder in the magnetic layer will be relatively reduced and the surface smoothness will be impaired, making it impossible to obtain good results in electromagnetic conversion characteristics.

In addition, in this invention, the above-mentioned Si is used as the non-magnetic powder.
,, N4 powder is used, but the conventional non-magnetic powder is replaced with the Si3N powder within a range that does not impair the above-mentioned effects.
There is no problem in using it together with 4 powders.

The magnetic recording medium of the present invention includes, for example, preparing a magnetic paint containing a magnetic powder, a binder, and the above-mentioned non-magnetic powder, and coating it on a substrate such as a polyester film so that the thickness after drying is usually 3 to 10 μm. It can be obtained by a known method such as coating to form a magnetic layer.

Examples of the magnetic powder include oxide-based magnetic powders such as T-Fe203 powder, Fe3O4 powder, Co-containing -Fe203 powder, Co-containing Fe powder, 04 powder, Cry□ powder, and barium ferrite powder, as well as Fe powder and Fe powder. - Any metal or alloy magnetic powder such as Ni powder or Fe-Co powder can be used. Furthermore, as the above-mentioned binder, conventionally known binders such as cellulose resins, polyvinyl chloride resins, polyurethane resins, polyester resins, acrylic resins, rubber resins, and incyanate compounds can be widely used. .

The magnetic layer formed by the above method contains various commonly used additives, such as lubricants such as fatty acids, fatty acid esters, silicone-based lubricants, and fluorine-based lubricants, and surfactants (dispersants). ), it goes without saying that an antistatic agent or the like may be included. [Effects of the Invention] As is clear from the above explanation, according to the present invention, Si3N4 powder is used as the non-magnetic powder. Accordingly, it is possible to provide a magnetic recording medium with good durability and longevity, which has a magnetic head with little wear, good electromagnetic conversion characteristics, and a magnetic layer with excellent wear resistance.

[Examples] Below, examples of the present invention will be described in more detail. In addition, in the following, parts shall mean parts by weight.

Example 1 Co-containing r-Fe203 powder (average particle size 0.4/'')
100 parts carbon black 4 parts Si
3N4 powder (average particle size 05μ) 10 parts Zinc stearate 0.5 parts Cyclohexanone 90 parts Toluene
90 parts The above components were mixed in a high speed stirrer for 5 to 10 hours, and then dispersed in a sand grinder, and the following components were added and mixed in a high speed stirrer.

After this mixing, the mixture was passed through a filter with a pore size of 1 μm to prepare a magnetic paint.

n-Butyl stearate 1 part myristic acid 2 parts cyclohexanone 35 parts toluene
35 parts of the above magnetic paint with a surface smoothness of 13
It was coated and dried on a polyester base film having a thickness of p so that the coating thickness after drying was approximately 5 μm. Thereafter, it was calendered and slit into 1/2 inch width to obtain the magnetic tape of the present invention.

Examples 2 to 7 In place of 10 parts of Si3N4 powder (average particle size 0.5 units), a non-magnetic powder shown in the table below was used to prepare a magnetic paint shown in the same table, and from this the same as in Example 1 was used. Then put the magnetic tape on it.

Comparative Examples 1 to 3 Same as Example 1 except that instead of 10 parts of Si3N4 powder (average particle size 0.57'1), non-magnetic powder shown in the table below was used in the number shown in the table. A magnetic paint was prepared, and a magnetic tape was made from this in the same manner as in Example 1.

1 for each magnetic tape obtained in the above Examples and Comparative Examples. The results of evaluating the following properties were as shown in the table below.

<Surface roughness of magnetic layer> Measure the center line roughness R of the magnetic tape using a stylus type surface roughness meter.
The a difference was measured.

<Color SN ratio> Record and reproduce the one-color chroma signal of a color video noise measuring device on a magnetic tape using a VH5 type VTR, measure the AM noise component, calculate the color SN ratio, and express it as a relative value with respect to the reference tape. did.

<Still characteristics> A magnetic tape is played back in still mode using a VH5 type VTR, and the playback output level is 5 dB from the initial value.
The evaluation was based on the time until the decrease.

<Head wear> VH8 type VTR under 40℃, 80%RH (7) environment
The magnetic tape was run 100 times using a 100-degree head, and then the head wear amount of the video head was measured.

As is clear from the table above, the magnetic tape of the present invention has a magnetic layer with a small surface roughness and excellent electromagnetic conversion characteristics, and the amount of wear on the magnetic head is small, and the magnetic layer has very good wear resistance. It can be seen that

Claims (1)

[Claims] (1) In a magnetic recording medium in which a magnetic layer containing magnetic powder and its binder is provided on a substrate, Si_
A magnetic recording medium characterized by containing 3N_4 powder.