JPH09320029A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve environmental resistance under an environment of a corrosive ambience, by providing a layer including a rust-preventive agent between a non-magnetic supporting body and a magnetic layer. SOLUTION: A mat layer 12 is formed on one face of a polymer film 2 as a non-magnetic supporting body. Fine particles 3 are dispersed in the mat layer 12 containing a rust-preventive agent. A magnetic layer 5 is formed on the mat layer 12 by slantwise vapor deposition, and further a carbon protecting film 6 and a lubricant layer 7 are sequentially formed. A back coat layer 8 is formed at the other face of the polymer film 2. The rust preventives is included 0.5-500mg per 1m<3> of a medium surface.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a magnetic recording medium. More specifically, it relates to a magnetic recording medium having excellent corrosion resistance.

[0002]

2. Description of the Related Art Conventionally, as a magnetic recording medium, a powder magnetic material such as an oxide magnetic powder or an alloy magnetic powder is coated on a non-magnetic support by a vinyl chloride-vinyl acetate copolymer, a polyester resin, a urethane resin, or the like. 2. Description of the Related Art A coating type magnetic recording medium prepared by applying and drying a magnetic paint dispersed in an organic binder such as a polyurethane resin is widely used.

On the other hand, with the growing demand for high-density magnetic recording, Co-Ni alloys, Co-Cr alloys,
-O or the like, a metal magnetic material is subjected to plating or vacuum thin film forming means (vacuum vapor deposition method, sputtering method, ion plating method, etc.) to form a polyester film or polyamide,
A so-called metal magnetic thin film type magnetic recording medium directly attached on a non-magnetic support such as a polyimide film has been proposed and attracted attention.

This metal magnetic thin film type magnetic recording medium is excellent in coercive force, squareness ratio and the like, and the thickness of the magnetic layer can be made extremely thin. Not only is it excellent in conversion characteristics, but it also has a number of advantages such that the packing density of the magnetic material can be increased because it is not necessary to mix a binder that is a non-magnetic material in the magnetic layer. That is, it is considered that the metal thin film medium becomes the mainstream of high-density magnetic recording due to its superior magnetic properties.

Further, in order to improve the electromagnetic conversion characteristics of this kind of magnetic recording medium and obtain a larger output, when forming the magnetic layer of the magnetic recording medium, the magnetic layer is obliquely formed. So-called oblique vapor deposition for vapor deposition has been proposed and put to practical use.

[0006] In the future, the medium tends to be smoothed in order to reduce spacing loss from the flow of further densification. The frictional force between the head and the medium increases with the smoothing of the medium, and the shear stress generated in the medium increases. In such a situation where the sliding durability becomes severe, a technique for forming a protective film on the surface of the magnetic layer has been studied for the purpose of improving the durability.

As such a protective film, a carbon film, a quartz (SiO ₂ ) film, a zirconia (ZrO ₂ ) film and the like have been studied, and some of them have been put to practical use in hard disks and produced. In particular, recently, diamond-like carbon (DLC), which has a higher hardness in carbon film,
The formation of a film such as a film has been studied, and it is a protective film that is expected to become mainstream in the future. As a method for forming the DLC film, a sputtering method and a CVD method are used.

In the sputtering method, first, an electric field or a magnetic field is used to ionize (make plasma) an inert gas such as Ar gas. Further, by accelerating the ionized argon ions, the target atoms are repelled by their kinetic energy. This is a physical process in which the ejected atoms are deposited on the opposing substrate to form a target film. The rate of forming a DLC film by this process is generally slow, and this is a film forming means having low productivity from an industrial viewpoint.

On the other hand, the CVD method is a chemical process of forming a film by utilizing the energy of plasma generated by using an electric field or a magnetic field to cause a chemical reaction such as decomposition and synthesis of a raw material gas. .

[0010]

By the way, although the carbon films formed by these methods have significantly improved sliding durability and environment resistance, especially corrosion resistance, they are corroded under high temperature and high humidity environment and SO ₂ gas. In a long-term storage under a strong atmosphere environment, the magnetic characteristics deteriorate due to the progress of oxidation and sulfide from the interface between the non-magnetic support and the magnetic layer, not from the surface of the medium. There was a problem of losing.

In view of the above points, the present invention provides a magnetic recording medium excellent in environmental resistance, particularly in corrosion resistance, without deteriorating the magnetic characteristics even when stored for a long time in a corrosive atmosphere environment. is there.

[0012]

A magnetic recording medium according to the present invention comprises an intermediate layer containing a rust preventive agent between a non-magnetic support and a magnetic layer. The presence of the rust preventive agent at the interface between the non-magnetic support and the magnetic layer prevents the progress of oxidation, sulfidation, etc. from the interface between the non-magnetic support and the magnetic layer, and improves the environment resistance to the magnetic layer, that is, the corrosion resistance. improves.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A magnetic recording medium according to the present invention has a structure in which an intermediate layer containing a rust preventive agent is provided between a non-magnetic support and a magnetic layer.

In the magnetic recording medium of the present invention, the magnetic layer is a metal magnetic film.

According to the present invention, in the above magnetic recording medium, an anticorrosive agent is added in an amount of 0.5 mg to 500 mg per 1 m ² of the medium surface.
Including the configuration.

According to the present invention, in the above magnetic recording medium, a layer containing a rust preventive agent is formed on the surface of the magnetic layer.

More specifically, the magnetic recording medium of the present invention comprises:
In order to ensure durability, when forming a fine particle coating layer called a mat layer on the polymer film of the non-magnetic support, a rust preventive agent was internally added to the paint to further improve the environmental resistance. The configuration.

In the present invention, all magnetic media (disks, tapes, etc.) in which a magnetic recording layer is provided on a non-magnetic support are targeted, but particularly in the tape media in which environmental resistance characteristics are strictly required unlike disks. Great effect.

A metal magnetic thin film is formed as a magnetic layer by directly depositing a ferromagnetic metal material on the non-magnetic support, and this metal magnetic material is used for a usual vapor deposition tape. Anything may be used as long as it is one. For example, ferromagnetic metals such as Fe, Co and Ni, Fe-Co, Co-Ni, Fe-Co-Ni,
Fe-Cu, Co-Cu, Co-Au, Co-Pt, M
n-Bi, Mn-Al, Fe-Cr, Co-Cr, Ni
-Cr, Fe-Co-Cr, Co-Ni-Cr, Fe-
Ferromagnetic alloys such as Co-Ni-Cr are exemplified. These may be a single-layer film or a multilayer film.

As a means for forming the metal magnetic thin film, a vacuum vapor deposition method of heating and evaporating a ferromagnetic material under vacuum to deposit it on a non-magnetic support, or an ion plating method of evaporating a ferromagnetic metal material in a discharge. A so-called PVD technique such as a sputtering method in which atoms on the target surface are knocked out by argon ions generated by glow discharge in an atmosphere containing argon as a main component may be used.

Of course, the structure of the magnetic tape according to the present invention is not limited to this, and may be changed without departing from the scope of the present invention, for example, a back coat layer may be formed or a medium surface may be formed if necessary. There is no problem in forming a layer of rust preventive agent, lubricant, etc. In this case, as the material contained in the non-magnetic pigment, the resin binder or the rust preventive agent, and the lubricant contained in the back coat layer, any conventionally known materials can be used. Further, the present invention is not necessarily limited to a medium having a protective film such as carbon on the surface.

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

First, the respective medium structures of the magnetic recording medium according to the comparative example and the magnetic recording medium according to the example of the present invention are shown in FIG.
Also, description will be made with reference to FIG. Comparative magnetic recording medium 1
As shown in FIG. 3, a mat layer 4 having fine particles 3 dispersed therein is formed on one surface of a polymer film 2 which is a non-magnetic support, and a magnetic layer formed by oblique vapor deposition is formed on the mat layer 4. 5 is formed, a carbon protective film 6 and a lubricant layer 7 are sequentially formed thereon, and a back coat layer 8 is formed on the other surface of the polymer film 2. However, the mat layer 4 does not contain a rust inhibitor.

On the other hand, in the magnetic recording medium 11 according to the embodiment of the present invention, as shown in FIG. 1, fine particles 3 are dispersed in the inside of one surface of the polymer film 2 which is a non-magnetic support, and the magnetic recording medium 11 is protected. A mat layer 12 containing a rust agent is formed, a magnetic layer 5 is formed on the mat layer 12 by oblique vapor deposition, and a carbon protective film 6 and a lubricant layer 7 are sequentially formed on the mat layer 12 to form a polymer film 2. The back coat layer 8 is formed on the other surface of the above.

Next, the experimental results of the present invention will be shown. <Comparative Example> In the medium structure of FIG. 3, a PET (polyethylene terephthalate) film having a thickness of 10 μm is used as the polymer film 2, and the following mat layer 4 containing no rust preventive agent is applied onto the PET film 2. afterwards,
A magnetic layer 5, a carbon protective film 6, and a lubricant layer 7 were sequentially formed, and a back coat layer 8 was formed on the back surface of the PET film 2 to prepare a magnetic recording medium 1 of a comparative example, and a corrosion test was carried out.

[Matt layer 4 solution] Fine particles 3: Polymethacrylic acid (average particle size 30 nm) Fine particle density: 10 million pieces / mm ² (after coating) Emulsion resin: Polyester (1.5 wt% solution) Solvent: Water 70 wt % + N-propyl alcohol 30 wt% Coating amount: 2.0 g / m ² (wet)

<Example> In the medium structure of FIG.
PET film having a thickness of 10 μm as the polymer film 2
On the PET film 2 and the mat of the comparative example
In the layer solution, naphthalenediol was added as a rust preventive.
(Corresponding to Example 1), benzotriazole (see Example 2)
Equivalent) and disodium dimercaptodiazole (implementation)
(Corresponding to Example 3) 0.5 wt% of the matte layer 12
The rust preventive agent after drying is 1 m on the surface of the medium ^Two10mg per
(0.5 mg-500 mg is suitable)
After forming the cloth, the magnetic layer 5 and the carbon protective film 6 are sequentially formed.
Then, the lubricant layer 7 is applied to the uppermost layer, and the PET film 2
A back coat layer 8 is formed on the back surface of each of Examples 1 and 2.
The magnetic recording medium 1 of Example 2 and Example 3 was prepared and subjected to a corrosion test.
Was carried out.

The vapor deposition conditions used in Comparative Examples and Examples are shown below. [Magnetic layer] Base film: thickness 10 mm PET Magnetic layer: thickness 200 nm, composition Co ₈₀ Ni ₂₀ single layer Incident angle: 45 ° to 90 ° Introduced gas: oxygen gas Vacuum degree during vapor deposition: 2 × 10 ^-2 Pa [Carbon Protective film] Raw material: Toluene Reaction pressure: 10 Pa Inlet power: DC 2.0 kV DLC film thickness: 8 nm Plasma emission part volume: 2000 cm ³ Inlet gas flow rate: 17 SCCM [Lubricant layer] Didodecyl phosphite (coating amount 20 mg / m ² : solvent) As ethyl alcohol)

As a test method, a thermostatic bath maintained at a temperature of 30 ° C. and a relative humidity of 70% was used to further add 0.5 ppm of S concentration.
An environment resistance test was conducted in which the sample was stored for 10 days in an O ₂ gas atmosphere environment, and the results are shown in Table 1.

In the evaluation, the change in the saturation magnetization before and after the storage was observed, and the definition of the amount of deterioration of the magnetization at that time was defined by the formula 1
Shown in

[0031]

[Equation 1]

[0032]

[Table 1]

As is clear from Table 1, the comparative example of -43
It can be seen that the deterioration amount after storage of each of Examples 1, 2, and 3 is about −5% or less, compared to%, and the storage property is significantly improved.

According to the above example, the non-magnetic support 2 and the magnetic layer 5 are
By forming a mat layer 12 containing a rust preventive agent between and, oxidation from the interface between the non-magnetic support 2 and the magnetic layer 5,
Sulfidation is prevented, the environment resistance of the magnetic layer, that is, the corrosion resistance is improved, and thus the reliability and long-term storage stability of the magnetic recording medium are improved.

Further, according to the present invention, as shown in FIG. 2, in addition to the structure of FIG. 1, a layer 13 containing a rust preventive agent is formed on the carbon protective film 6.
The magnetic recording medium 14 can also be prepared by forming the lubricant layer 7 via. With this configuration, the corrosion resistance against the corrosion from the surface of the magnetic medium is further improved.

[0036]

According to the magnetic recording medium of the present invention, the presence of the layer containing the rust preventive agent between the non-magnetic support and the magnetic layer makes it possible to corrode under high temperature and high humidity environment or SO ₂ gas. Improved environmental resistance in a polar atmosphere, which in turn increases the reliability of magnetic recording media, especially tape media, and can withstand special applications such as data streamers and video libraries that require long-term storage. It becomes possible to provide magnetic recording tape.

Further, when a layer containing a rust preventive agent is formed on the magnetic layer, corrosion from the surface of the magnetic recording medium can be prevented more reliably, and the environment resistance is further improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a magnetic recording medium according to the present invention.

FIG. 2 is a configuration diagram showing another embodiment of the magnetic recording medium according to the present invention.

FIG. 3 is a configuration diagram of a magnetic recording medium according to a comparative example.

[Explanation of symbols]

1, 11, 14 magnetic recording medium, 2 polymer film,
3 fine particles, 4 mat layer, 5 magnetic layer, 6 carbon protective film, 7 lubricant layer, 12 mat layer containing rust preventive agent, 1
3 Layer containing rust inhibitor

Claims (4)

[Claims] 1. A magnetic recording medium comprising an intermediate layer containing a rust preventive between a non-magnetic support and a magnetic layer. 2. The magnetic recording medium according to claim 1, wherein the magnetic layer is a metal magnetic film. 3. The rust preventive agent is contained in an amount of 0.5 mg to 500 mg per 1 m ^{2 of} the medium surface.
3. The magnetic recording medium according to claim 1. 4. The magnetic recording medium according to claim 1, wherein a layer containing a rust preventive agent is formed on the surface of the magnetic layer.