JPH0668836B2 - Magnetic recording medium - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a magnetic tape or a magnetic disk, and more particularly to a magnetic recording medium most suitable for a rotary head type video tape recorder.

Conventional technology Cobalt, nickel, iron, or alloys containing them as the main component are formed by vacuum deposition, sputtering, ion plating, or other vacuum film forming methods from polyester films, polymer films such as polyimide films, or nonmagnetic thin metal plates. The ferromagnetic metal thin film type magnetic recording medium formed on the substrate is capable of dramatically improving the recording density as compared with the conventional coating type magnetic recording medium. It is necessary to flatten the surface of the magnetic recording medium as much as possible to reduce the spacing loss between the magnetic head and the magnetic recording medium as much as possible. However, if the surface is excessively flattened, head touch and running performance will be hindered, and the reproduction life may become extremely short especially in the still mode in the reproduction of video signals. These problems have been solved by providing a surface coating layer made of various organic lubricants and resins at the same time as roughening the surface. As such a surface coating material, various fatty acid esters, fatty acid amides, lubricants such as silicone oil and fluorine oil, and resins such as polyamide resin and epoxy resin have been used alone or in various compound forms.

Problems to be Solved by the Invention In terms of still reproduction life, each of the above various surface coatings usually has a life of 30 minutes or more at room temperature and humidity, but a humidity of 20% RH or less, and As a result of the study conducted by the present inventors, it has become clear that when it is less than% RH, the life is reduced to 30 minutes or less, or even if it is not reduced, many white spots running horizontally appear in the reproduced image.

Means for Solving the Problems The present invention relates to a magnetic recording medium characterized in that a thin layer containing a fluorinated phenyl derivative is formed on a ferromagnetic metal thin film containing oxygen. The above-mentioned problems are solved by the strong action of protecting the surface of a magnetic metal under a low humidity of a phenyl derivative.

The fluorinated phenyl in the present invention means a structure in which a fluorine atom and / or a fluoroalkyl group is directly bonded to the phenyl ring.

In the present invention, the following general formula (I) or (II) or general formula (I) is provided on a ferromagnetic metal thin film having improved surface hardness, corrosion resistance and adhesion of a surface coating material by containing oxygen. General formula (II): [However, in the general formula (I) or (II), R ¹ and R ³ represent a fluorine atom or a fluorinated hydrocarbon residue having 1 to 22 carbon atoms, l represents an integer of 1 to 5, and p Is 1
Represents an integer of ~ 4. R ² and R ⁴ represent a hydrogen atom or a hydrocarbon residue having 1 to 22 carbon atoms, m represents an integer of 5-l, and q represents an integer of 4-p. n, r, and s each represent an integer of 0-10. m, u, and v each represent an integer of 0 or 1. A, B, and C are oxygen, sulfur,
It represents a polar group having a bond terminal at any atom of phosphorus. ] A thin layer containing a fluorinated phenyl derivative represented by the following formula is formed.

Action With the above structure, the fluorinated phenyl derivative has a strong magnetic metal surface protection action under low humidity and a sliding action, and thus a stable still under a low humidity environment where the adhesion of ferromagnetic metal to the magnetic head is likely to occur. This is to maintain the reproduction durability.

Embodiments Embodiments of the present invention will be described below with reference to the drawings.

The figure shows the basic structure of a magnetic recording medium in an embodiment of the present invention. In the figure, 1 is a substrate, 2 is a ferromagnetic metal thin film, and 3 is a surface coating layer. The surface coating layer 3 is formed of a thin film layer containing a fluorinated phenyl derivative.

Examples of the fluorinated phenyl derivative used in the present invention include (1) carboxylic acids (2) Alcohol (3) Phosphoric acids (4) Ethers (5) Esters (6) Mercaptans Etc. In the fluorinated phenyl derivative used in the present invention, at least one or more fluorophenyl group, fluoroalkylphenyl group, fluorophenylene group, or
Those having a fluoroalkylphenylene group and having a ratio of the molecular weight of these groups to the total molecular weight of 5% or more are suitable. If this ratio is 5% or less, it becomes difficult to obtain the effects of the present invention. By incorporating a long-chain perfluoroalkyl group or an aliphatic alkyl group into the fluorinated phenyl derivative as seen in some of the above examples, it is possible to further improve the lubricity of itself.

However, if the number of carbon atoms in the long-chain perfluoroalkyl group or the aliphatic alkyl group is 23 or more, the solubility of the solvent as a constituent molecule becomes poor and the handling becomes difficult.

On the ferromagnetic metal thin film, the fluorinated phenyl derivative is 0.1 to 500 mg, more preferably 0.5 to 200 mg, per 1 m ³ of the surface.
It is advisable that the ratio of the above is present alone or in the form of a thin layer as a composite with another lubricant, rust preventive, resin or the like. Further, as a method of making it exist, in addition to the method of directly coating or vapor depositing on the ferromagnetic metal thin film, it is applied or vapor-deposited on the back surface of the magnetic recording medium, and when the magnetic recording medium is laminated (when wound). A method of transferring to the surface of the ferromagnetic metal thin film is also possible.

As the ferromagnetic metal thin film, for example, a metal thin film mainly composed of Co, Ni, Fe or the like formed by oblique vapor deposition or vertical vapor deposition, or a metal thin film mainly composed of an alloy thereof (for example, CoN
(i, CoCr, etc.), which contains oxygen obtained when the atmosphere during film formation is an atmosphere in which oxygen gas is oxidative. The oxygen content is at least 3% or more, preferably 5% or more, in terms of atomic number ratio to the ferromagnetic metal. If it is 3% or less, the effect of the present invention cannot be obtained.

As a substrate on which a ferromagnetic metal thin film is to be formed, one having macroscopically good surface smoothness and having fine projections is suitable. For example, a surface height of 50 to 600Å and an average of 1 mm ² per 1 mm ^2. A polyester film having × 10 ⁴ to 10 ⁸ wavy or mountain-shaped protrusions is particularly preferable.

Wavy projections (height 100 Å density 1 × 10 ⁶⁾ obtained by coating and curing a modified silicone emulsion liquid containing a thickener on the surface of a polyester film that contains almost no fine particles due to polymerization catalyst residues during stretching. Pieces / m
m ²⁾ CoNi ferromagnetic metal thin film (Ni = 20% by continuous vacuum oblique evaporation on the ones allowed form, a film thickness 1000 Å) was allowed formed in the presence of trace amounts of oxygen. The oxygen content in the film was 5% in terms of atomic number ratio. This sample is designated as A.

Gradient projections with a gradual slope due to silica fine particles added to the polyester film (average height 70 Å average diameter 1
of 100 μm ² per 100 μm ^{2 on the} surface, and the UV curable epoxy resin is bonded to the surface of the polyester film with 150 Å diameter colloidal silica as the core on the surface of the polyester film that has minimized the relatively large protrusions due to the fine particles due to the polymerization catalyst residue. CoNi film (Ni = 20% by steep mountain-like protrusions of 1 × 10 ⁷ cells / mm ² formed allowed the same conditions as described above on a substrate to be agents,
A film having a film thickness of 1000Å and an oxygen content of 7%) was formed as B
And In addition, as a comparative example, in B, oxygen was not introduced during vapor deposition (in B, only the oxygen content was 2
% Or less) is referred to as C. A solution of various fluorinated phenyl derivatives prepared in advance is applied on these vapor-deposited films to form a thin layer, and then cut into a predetermined width to make a magnetic tape, which are made at 20 ° C and 15% RH for trial production video. The still reproduction characteristics were measured by hanging it on a deck, and the time when a white spot running laterally in the reproduced image began to appear (white spot occurrence time) and the time when the reproduced image began to be completely disturbed (lifetime) were obtained. The results are summarized in the following table. As a comparative example,
Fluorine-containing derivatives containing perfluoroalkyl groups that do not contain fluorinated phenyl groups, (12), (13), (14), higher fatty acids and their derivatives, (15), low oxygen content in magnetic films Things ... (7) etc. are added.

EFFECTS OF THE INVENTION As is clear from the above table, the magnetic recording medium of the present invention has a very high industrial value because good image quality can be obtained during still reproduction under low humidity and its life is long and stable. It is a thing.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is a cross-sectional view of one embodiment of a magnetic recording medium of the present invention. 1 ... Substrate, 2 ... Ferromagnetic metal thin film, 3 ... Surface coating layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuo Nakamura 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Susumu Enomoto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 56) References JP-A-57-44226 (JP, A) JP-A-58-188329 (JP, A)

Claims (1)

[Claims] 1. A magnetic recording medium characterized in that a thin layer containing a fluorinated phenyl derivative represented by the following general formula (I) or (II) is formed on a ferromagnetic metal thin film containing oxygen. General formula (I): General formula (II): [However, in the general formula (I) or (II), R ¹ and R ³ represent a fluorine atom or a fluorinated hydrocarbon residue having 1 to 22 carbon atoms, l represents an integer of 1 to 5, and p Is 1
Represents an integer of ~ 4. R ² and R ⁴ represent a hydrogen atom or a hydrocarbon residue having 1 to 22 carbon atoms, m represents an integer of 5-l, and q represents an integer of 4-p. n, r, and s each represent an integer of 0-10. m, u, and v each represent an integer of 0 or 1. A, B, and C are oxygen, sulfur,
It represents a polar group having a bond terminal at any atom of phosphorus. ]