KR920009772B1 - Magnetic medium - Google Patents

Abstract

The magnetic recording medium is prepared by forming a magnetic layer onto the non-magnetic substrate. Specifically the magnetic layer is composed of 100 wt.% hexagonal ferrite magnetic powder (1) and 0.1-50 wt.% of betaine compound (2) as an antistatic agent. The betaine compound is carboxylic betaine such as alkyldimethyl betaine or lauryldimethyl betaine. The medium has good eletromagnetic conversion characteristics and durability.

Description

Magnetic recording media

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high density, high precision magnetic recording medium, and more particularly to a magnetic recording medium having high electronic conversion characteristics and improved driving durability and recording stability in magnetic recording media for audio, video, and computer recording.

Recently, reproducing apparatuses of magnetic recording media such as video tapes have been developed with high technology in response to high density and high precision. Therefore, magnetic recording media having severe use conditions in these playback apparatuses require high recording stability and accurate signal output upon reproduction, with high density recording.

Therefore, these playback devices generate signals due to friction between the magnetic recording medium and the head, but in this process, recording and playback signals are degraded due to an increase in the friction coefficient and generation of static electricity. In order to solve these problems, the magnetic layer may include carbon black and / or surface abrasive, which is an antistatic agent.

Examples of use as a conventional antistatic agent include a method of adding one or two or more of glycerin, ethylene glycol, and triethylene glycol together with carbon black (Japanese Patent Publication No. 39-28369, 60-136030), and carbon in the intermediate layer. Method of adding black (Japanese Patent Application Laid-Open No. 60-193130) A method of containing pulverized carbon black in a magnetic layer (Domestic Publication No. 86-632) and the like have been proposed.

However, these methods not only reduce the dispersibility of the magnetic particles and the filling property of the magnetic coating film, but also have poor compatibility with the use of hexagonal ferrite suitable for high density recording, thereby reducing the high electron conversion characteristics and the recording stability, thereby reducing the high-density magnetic for high density. It is not suitable for recording media.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems and to provide a magnetic recording medium for high density recording with improved electronic conversion characteristics and recording stability, and according to the present invention, the antistatic property and S of the magnetic recording medium using hexagonal ferrite as magnetic particles A magnetic recording medium comprising a betaine compound together with a specific surface area of 100 m 2 / g carbon black for improving the / value is provided. The betaine compound includes a carboxyl beta-based and sulfobeta-based ones, which are effective for the present invention, and preferably dimethyl betaine and lauryl dimethyl betaine as carboxyl betaine-based compounds.

According to the present invention, in a magnetic recording medium having a magnetic layer on a nonmagnetic support, the magnetic recording medium contains beta and its derivative compounds together with carbon black as an antistatic material, and the betaine compound is a magnetic powder. It is to provide a magnetic recording medium of 0.1 to 5.0 parts by weight with respect to parts. In a preferred embodiment, the addition amount of the betaine compound is preferably 0.1 to 5.0 parts by weight based on 100 parts by weight of the magnetic powder hexagonal ferrite in the magnetic layer. In 0.1 parts by weight or less, the antistatic effect is significantly lowered and 5.0 parts by weight or more. When added, the surface characteristics of the magnetic recording medium are deteriorated, resulting in poor friction characteristics and running stability.

As a method for containing the betaine compound in a magnetic layer, the above-mentioned material is added to a magnetic coating made of hexagonal ferrite and a binder and the like is applied on a nonmagnetic support to form a magnetic layer, or the water is a suitable solvent, for example For example, a method of dissolving in toluene, methyl ethyl ketone, and the like, dispersing carbon black in the solution, and then adding it to a magnetic paint is applied to a nonmagnetic support to form a magnetic layer.

As the magnetic powder used in the present invention, a hexagonal ferrite CrO ₂ ferromagnetic component or the like suitable for high density recording can be used. In particular, hexagonal ferrite is suitable for the production of high-density high precision magnetic recording media. For example, Co, Fe, Ni-containing Co alloy, MnBi alloy, MnAl alloy, various earth and Co alloys such as Ba, Sr, Pb, Ca, Hexagonal ferrite or part containing RCo _6, R ₂ Co ₁₇ or the like is selected from the group of Al, V, Nb, Zr, Ca, In, Zn, Cu, Mn, Ni, Ti and Co and substituted with at least one kind of element And hexagonal ferrites. Among these magnetic components, substituted hexagonal ferrites were found to be very suitable in the present invention.

The high-density, high-precision magnetic recording medium manufactured by the present invention exhibited extremely excellent electron conversion characteristics, recording stability, running stability, and the like, compared with the conventional one.

The present invention is explained in more detail in the following examples.

EXAMPLE

1.0 parts by weight of an alkyldimethylbetaine compound was added using the above compound as a basic composition, mixed with a sand mill manufactured by NETZSCH, and then the following composition was added and dispersed for 8 hours.

Immediately before coating, 5.0 parts by weight of Colonnet C-3041, a product of Nippon Polyurethane Industry Co., Ltd., is stirred at 1200 RPM or more for 30 minutes.

The magnetic coating prepared from the above-described composition is coated on a nonmagnetic support acid so as to have a thickness of 2.5 μm to 3.0 μm, dried after magnetic field orientation, and wound up. After treating this with a calendar, it hardened at 60 degreeC for 48 hours, cut the width to 8 mm, and used it as the evaluation sample.

Example 2

Except for using the same amount of lauryl dimethyl betaine instead of the alkyl dimethyl betaine in the magnetic paint preparation composition was carried out in the same manner as in Example 1.

Comparative Example 1

Except for using the same amount of triethyl glycol instead of the betaine compound in the magnetic coating preparation composition was carried out in the same manner as in Example 1.

Comparative Example 2

The composition was carried out in the same manner as in Example 1 except that the same amount of titanium monoxide was added instead of the carboxyl betaine compound in the composition.

Comparative Example 3

The same procedure as in Example 1 was conducted except that the same amount of sorbitol distearate was added instead of the carboxyl betaine compound in the composition.

The characteristics of the evaluation sample made by the above comparative example are shown in the table below.

[table]

As can be seen from the above surface, the magnetic recording medium using the betaine compound as an antistatic agent used in the present invention can be seen to have extremely excellent electron conversion characteristics, surface electrical resistance and dynamic friction coefficient. It can be seen that it is suitable. On the other hand, as shown in the comparative example, when the above water is not used, it can be seen that the properties are inferior.

Claims (4)

A high density high precision magnetic recording medium having a magnetic layer using hexagonal ferrite on a nonmagnetic support, wherein the magnetic layer contains a betaine compound or a derivative thereof as an antistatic agent. The magnetic recording medium according to claim 1, wherein the amount of the betaine compound added is 0.1 to 5.0 parts by weight based on 100 parts by weight of the hexagonal ferrite magnetic powder in the magnetic body. The magnetic recording medium of claim 2, wherein the betaine compound is a carboxyl betaine system. 4. The magnetic recording medium of claim 3, wherein the betaine compound is alkaldimethyl betaine or lauryldimethyl betaine.