JPS598124A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve considerably the clogging of a head by forming a magnetic thin film on one side of a nonmagnetic substrate and a resin film contg. fine inorg. powder having a surface layer of tin oxide on the other side. CONSTITUTION:A ferromagnetic metallic thin film is formed on one side of a nonmagnetic substrate, and a resin film contg. fine inorg. powder having a surface layer of tin oxide is formed on the other. The inorg. powder has 0.01- 0.5mum particle size, and the surface layer is made of tin oxide such as SnO or SnO2 or a mixture of tin oxide with 0.1-20% indium oxide, antimony oxide or the like. The inorg. powder is made of an electrically insulating oxide such as titanium oxide, silica or alumina. The amount of the fine inorg. powder to be added is 10-500pts.wt., preferably 50-400pts.wt. per 100pts.wt. resin component, and the desired thickness of the resin film is 0.1-1mum.

Description

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to stabilize the running of a ferromagnetic metal thin film type magnetic recording medium, particularly a magnetic tape, and to improve head clogging during running.

Vacuum deposition and sputtering of iron, cobalt, nickel, alloys containing these as main components, or metal thin films containing oxygen.

Ferromagnetic metal thin film magnetic recording media, which are formed on polymer film substrates such as polyester films and polyimide films using vacuum film forming methods such as ion blating, have dramatically higher recording densities than conventional coated magnetic recording media. However, the higher the density, the more the gap between the head and the magnetic recording medium will severely affect the characteristics due to spacing loss, and even if a small amount of foreign matter adheres to the head, it will This will lead to a decrease in output as a head clogging phenomenon. In addition, since the magnetic layer is made of ferromagnetic metal and is a conductor, the substrate film is easily charged with electricity during running, and to prevent this, it is necessary to lower the insulation resistance of the back side, and the back side is coated with carbon, graphite, etc. A method is used to provide a layer, but when the magnetic tape is rolled up and twisted, some of the mixture of carbon, graphite, and the resin that binds them is transferred to the magnetic surface, and then the tape is rolled up and twisted. When this occurs, they sometimes adhere to the vicinity of the gap in the head, causing head clogging. As a result of the studies conducted by the present inventors, inorganic fine powder having a tin oxide surface layer has a property that it is difficult to adhere to the head, and even when it is mixed into the back coating layer, its effect is fully exhibited. It has also been revealed that the antistatic effect is also great. That is, the present invention relates to a magnetic recording medium in which a ferromagnetic metal film is formed on one side of a nonmagnetic substrate, and a resin film containing inorganic fine powder having a tin oxide surface layer is formed on the other side. .

The inorganic fine powder having a tin oxide surface layer used in the present invention is a tin oxide such as SnO or 5n02 on the surface, or a tin oxide such as indium oxide or antimony oxide on the surface.
Forming a thin layer consisting of 1 to 20% additive,
Particle size 0. It is an inorganic fine powder with a diameter of 1 to 0.6 μm. Inorganic fine powder refers to electrically insulating oxides such as titanium oxide, silica, and alumina.

The above powders are vinyl chloride-based and ester-based.

Dispersed in urethane-based, epoxy-based, etc. resin solutions,
If necessary, carbon blank, graphite, molybdenum disulfide, calcium carbonate, fine powder such as alumina, fatty acids, fatty acid esters, fatty acid amides, metal soaps, fatty alcohols, paraffin, various lubricants such as silicone, etc. A resin film is formed by adding a surfactant, various rust preventive agents, etc. and applying the mixture to the back surface of a plastic substrate. The fine powder mainly composed of tin oxide is added in an amount of 1 to 500 parts by weight, particularly preferably 60 to 400 parts by weight, per 10 parts by weight of the resin component. Further, the thickness of the resin film is preferably 0.1 to 1 μm.

As a ferromagnetic metal thin film, iron, cobalt, nickel, or their alloys can be made by vacuum evaporation, ion blating,
Thin films formed directly on a substrate by sputtering, etc. or via a non-magnetic base such as aluminum, titanium, chromium, etc., or those in which the above-mentioned non-magnetic thin film is inserted as an intermediate separator between ferromagnetic thin films, etc. In particular, a ferromagnetic thin film, a thin underlying film, and a thin underlying film that contains oxygen (partially oxidizes the metal) to improve adhesion strength to the substrate, corrosion resistance, magnetic properties, etc. are desirable. .

Examples of the present invention will be described below.

Example 1 A polyester film having a thickness of 12 μm and having fine protrusions on both sides with a surface roughness Rmax=300″ was placed along the circular surface of a cylindrical can, and oxygen gas was blown at a vacuum level of 5×10!1 rOrr. CoNi alloy (N1 content 20w) introduced at a flow rate of 0.31/□ and melted by electron beam heating.
A 1000X thick oxygen-containing CoNi ferromagnetic thin film was formed on the film by continuous oblique evaporation (cutting the low incident angle component 30° or less), and a solution with the following composition was applied to the back side of this film. After applying and drying,
The magnetic tape was cut into a predetermined length using a slitter.

Composition: Fine powder with a thin tin oxide layer formed on the surface of titanium oxide (
Product name W-1Made by Mitsubishi Metals ■) ・・・・・・・・・・・・1 oQF! Polyester resin (Byron 200. Manufactured by Toyobo ■)・・・・・・・・・
...60g Butyl acetate...300g Toluene...
・・・・・・・・・・・・・・・20(1) After leaving this tape sample in a 60'C65%R,H atmosphere for 10 days,
When I checked for clogging by playing back the recording on a video deck, no clogging occurred.

Comparative Example 1 In Example 1, a magnetic tape obtained using the following composition liquid was left at high temperature under the same conditions as in Example 1, and clogging was examined. The image is distorted.

Composition: Graphite・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・2Qg polyester resin (Vylon 2oo)・・・・・・50g Butyl acetate・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・3oog toluene・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・・・・20
As is clear from the above, the magnetic recording medium of the present invention has greatly improved head clogging and is of great industrial value.

Claims (1)

[Claims] A ferromagnetic metal thin film is formed on one side of a non-magnetic substrate, and a ferromagnetic metal thin film is formed on the other side.
A magnetic recording medium characterized in that a resin film containing inorganic fine powder having a tin oxide-based thin film is formed on the surface.