JPS6352326A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To satisfactorily disperse magnetic particles and to improve magnetic characteristics and surface characteristics by incorporating a specific aluminum coupling agent into a magnetic layer. CONSTITUTION:This magnetic recording medium contains the aluminum coupling agent expressed by the formula at 0.1-10.0% ratio to the magnetic powder in a magnetic coating compd. coated on a nonmagnetic substrate. (In the formula, R is a hydrocarbon group.) The aluminum coupling agent reacts powerfully with the hydroxyl group on the powder surface upon contact with the magnetic powder and to aluminum atoms bond securely through oxygen atoms onto the surface of the magnetic powder. This type of the aluminum coupling agent, therefore, forms a film by sticking securely to the particle surface of the magnetic powder when said agent is incorporated into the magnetic layer. The dispersibility of the magnetic powder is thus extremely improved, by which the magnetic characteristics and surface smoothness are improved. The mixing ratio of the coupling agent is preferably in a 0.1-10.0%, more preferably 1.0-3.0% range.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a coated Tj type magnetic recording medium, which has good dispersibility of magnetic powder, excellent magnetic properties and surface smoothness of the magnetic layer, and is suitable for use in fc magnetic tapes, It relates to magnetic recording media such as magnetic disks.

BACKGROUND ART Magnetic recording media are required to have good surface smoothness, magnetic properties, and fire resistance. Furthermore, electromagnetic conversion characteristics, wear resistance, and moisture and heat resistance characteristics are essential requirements for magnetic recording media.

In order to meet these demands, attempts have been made to improve the dispersibility of the magnetic powder by treating the magnetic powder with a dispersant in advance to improve the magnetic properties and surface smoothness as well as the wear resistance of the lid. The analogy is JP-A-53-15923
Publication No. 0 adopts a method in which a tertiary aban compound is present in the entire magnetic layer, but other methods have also been proposed in which fatty acids such as stearic acid and oleic acid, % IJ corn oil, etc. are present. However, the dispersibility of the magnetic powder is still insufficient, and improvements in magnetic properties and surface properties are still far from satisfactory.

C) Problems to be solved by the invention In the conventional example described above, in order to improve the dispersibility of the magnetic powder, a dispersant having a high affinity for the hydroxyl group (-OH) present on the surface of the magnetic powder is used. Dispersibility is improved by weakening the interaction between powder particles, but these substances do not react with the magnetic particle surface, but are simply adsorbed to the magnetic particle interface by weak effects such as hydrogen bonding force. be. Therefore, the dispersibility of magnetic particles is low and unstable.

The great invention aims to sufficiently disperse magnetic particles and improve magnetic properties and surface properties.○2) Means for solving all problems Aluminum can be coated with aluminum by adding the solution when preparing the magnetic paint, or more preferably by immersing the magnetic powder in this solution to pre-treat the surface of the magnetic powder, and then using this magnetic powder to prepare the magnetic paint. 0.1 to IQ, Q to the magnetic powder in the magnetic paint in the magnetic layer.
It is contained at a ratio of 96%.

E) Action When the aluminum-based coupling agent used in the present invention comes into contact with magnetic powder, it reacts strongly with the hydroxyl groups on the surface of the powder, and forms a strong bond to the surface of the aluminum-like powder via acid atoms. . Therefore, when this type of aluminum-based coupling 41 is contained in the magnetic layer, it adheres strongly to the particle surface of the magnetic powder and forms a broken film, so that the dispersibility of the magnetic powder becomes much better.t) Magnetic properties and Surface smoothness is improved.

Furthermore, when a vinyl chloride resin is used as a binder component, this resin not only contributes to improving the dispersibility of magnetic powder to some extent by itself, but also works together with the aluminum coupling agent in the Vr-5Ef layer. When contained, it increases the affinity with the magnetic powder, further improving the dispersibility of the magnetic powder.In addition, in the magnetic coating, the vinyl chloride resin is cross-linked via the aluminum coupling agent and the magnetic powder. shape and improves wear resistance.

(f) Examples The feature of the present invention is that the magnetic paint used in the production of a coating-type magnetic recording medium, that is, the non-magnetic substrate (for example, PET tape)
Since the composition of the magnetic layer applied thereon depends on the composition, the following explanation will mainly focus on the composition and manufacturing method of the magnetic paint used in the magnetic recording material of the present invention.

Examples of the magnetic powder used in the present invention include γFe2O
3 powder, Co-containing Fe1203 powder, crO2 powder, and metal powders such as Fe powder and Fe-N1 powder. Particularly in the case of the present invention, it should be noted that if the metal powder is used with a thin oxide layer formed on its surface, the effect of using the aluminum coupling agent in combination will be greater.

As the aluminum coupling agent, acetalkoxyaluminum diisopropylate is used. This substance is represented by the following structural formula.

OH5 However, R is a hydrocarbon group.

This coupling agent is sold by Imouto Co., Ltd. under the name AL-M, and has the property of chemically bonding to the surface of an inorganic material and forming an organic material. The mixing ratio of the car tooling agent to the magnetic powder is 0.1 to 10.
In the range of 0.096, it is particularly desirable that the value be 1.0 to 3.096. If the value is outside the former range, desired characteristics may not be obtained due to a bleed-out phenomenon.

However, in the present invention, a magnetic paint is prepared by mixing vinyl chloride resin used as a binder component with magnetic powder surface-treated with an aluminum-based nongluing agent. VAG manufactured by US company U, 'C, C
Examples include H (vinyl chloride-vinyl acetate-vinyl alcohol copolymer). When this resin is contained in the magnetic layer together with the aluminum-based coupling agent, it increases the affinity with the magnetic powder, so it is desirable to use it in combination with the coupling agent.

The organic solvent (solvent) may be one or more solvents suitable for dissolving the Al and miniram coupling agents and binder components used, such as toluene, methyl ethyl ketone, ethyl acetate, and cyclohexanone, without particular limitations. used in combination. In addition, other commonly used binder components may be used in combination with the magnetic paint if necessary, and various commonly used additives such as dispersion abrasion, lubricants, gfm, antistatic, etc. It is completely acceptable to add genealogy and use agents etc. as appropriate. □ I will explain one embodiment of the present invention to Yaya. In one embodiment, the magnetic paint layer 11 in Example 2 contains the following O Co containing r Fc20s 1iJO heavy IV
AGH H12-1QB (manufactured by U, C, C, USA, vinyl chloride/vinyl acetate/vinyl alcohol copolymer) Niraporan N-50338 parts by weight (manufactured by Nippon Polyurethane Kogyo Co., Ltd., polyurethane elastomer) Coronate L 5 parts by weight (Japan Polyurethane Kogyo Co., Ltd., trifunctional low molecular weight isocyanate compound) AL-IJ 1.8 parts by weight (
Manufactured by Ajinomoto Co., Ltd., carbon black 5 parts by weight Methyl ethyl ketone
100 parts by weight toluene 100
A method for producing magnetic candy based on such a composition will not be described in detail since well-known methods can be adopted, but the simplest method is to mix the entire composition in a sand grinder for approximately 5 hours. This is a method of dispersing and adjusting magnetic paint.

In order to improve the dispersibility of graphite, etc., it may be possible to use a mixed process. By taking advantage of the characteristics of the aluminum coupling agent mentioned above, it is chemically bonded to the surface of the magnetic powder. In order to create an organic layer and ensure its dispersibility, the magnetic powder is immersed in a solution in which the above-mentioned coupling agent is dissolved in a solvent such as toluene, MEK, or ethyl acetate cyclohexane, and the magnetic powder is surface-treated in advance. After that, how to knead with the remaining composition? It is desirable to take that time,
In order to measure the quality of the reprocessing, a solution was prepared in advance by dissolving the coupling solution in a solvent such as toluene, and the color was mixed with the composition of the pond and a separately kneaded magnetic powder to adjust the color. In Example 0, in which a method of manufacturing a magnetic paint with a desired concentration can be adopted, the mother paint prepared in this way is
1 μm of PG'R (O effect) applied on a polyethylene terephthalate film to a dry thickness of about 4 μm, dried, processed, surface treated, and then cut to a predetermined width to create a magnetic tape. Two comparative examples prepared for confirmation are as follows.

Comparative Example 1 A magnetic tape was made in the same manner as in the example except that AL-M was completely omitted in the composition of the magnetic paint in Example 2. Comparative Example 2 In the composition of the Ffi paint in the example, AL-M
A magnetic tape was made in the same manner as in the example except that the same amount of the tertiary amine compound (Kao Atlas Co., Ltd. Aminated 105) contained in the polyalkylene oxide was used instead. Video SN of magnetic tape obtained in example
The 0 measurement value obtained by measuring the video SN ratio and color SN ratio of the magnetic tape obtained in Comparative Example 1 is 0.
The 0-order table is the result, expressed as the difference from that.

Table 1 Furthermore, the squareness ratio (Br/8m) and the surface roughness of the magnetic layer surface were measured. The surface roughness was measured using a stylus type surface roughness meter.

The following table shows the results.

Table 2 As is clear from Table 1.2, the magnetic tape of the present invention has higher video SN ratio and color SN ratio, and better squareness ratio and surface roughness than conventional magnetic tape. From this, it can be seen that the discharge recording material obtained with Fuinvention 11CL has poor dispersibility of the magnetic powder, but the smoothness of the magnetic layer surface is good, and the magnetic properties are even better than the above.

Claims (4)

[Claims] (1) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (However, R in the formula is a hydrocarbon group.) A magnetic recording medium characterized by containing 0.1 to 10.0% in proportion to magnetic powder. (2) The magnetic recording medium according to claim 1, wherein the coupling agent is added in the form of a solution in a solvent such as toluene or MEK when preparing the magnetic paint. (3) Magnetic recording according to claim 1, characterized in that magnetic powder is immersed in a solution in which the coupling agent is dissolved in a solvent such as toluene or MEK, and the surface of the magnetic powder is previously subjected to surface treatment. Medium. (4) The magnetic recording medium according to any one of claims 1 to 3, characterized in that a vinyl chloride resin is used as the binder.