JPS63282915A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the title magnetic recording medium with a plastic substrate and having excellent durability by forming the plastic substrate film with plural thin substrate films, and using a material highly adhesive to the respective adjacent materials to laminate and form the thin substrate film. CONSTITUTION:A plated substrate film 2, a nonmagnetic metal plated layer 3, a magnetic substance layer 4, and a lubricating and protecting layer 5 are laminated in this order on both sides of a plastic substrate 1 to form the magnetic recording medium. The plated substrate film 2 is formed by laminating plural thin substrate films, namely a first thin substrate film 2a and a second thin substrate layer 2b, a material highly adhesive to the plastic substrate 1 is selected as the first thin substrate film 2a, and a material highly adhesive to the nonmagnetic metal plated layer 3 is selected as the second thin substrate film 2a. The nonmagnetic metal plated layer 3 is used as the substrate for the magnetic substance film 4, and is used for enhancing the surface hardness of the plastic substrate 1. By this method, a lightweight magnetic recording medium having excellent durability can be produced at a low cost.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to magnetic recording media.

[Background technology]

In recent years, magnetic recording and reproducing devices are becoming smaller, lighter, and more dense. For this reason, there is an increasing need for media that can record at high density.

Usually, an aluminum alloy disk is used as the substrate of this medium. However, in the case of aluminum alloys, machining,
Mirror finishing such as wrapping is required. Therefore, there is a problem that the obtained substrate is very expensive.

Glass substrates and ceramic substrates have also been proposed as alternatives to this aluminum alloy substrate. However, in either case, there is a problem in that a large number of man-hours are required for surface polishing in order to make the surface sufficiently smooth. Moreover,
In the case of glass substrates, there was also the problem that they were easily broken.

In contrast, plastic substrates have been proposed as materials that can easily form smooth surfaces.

By using plastic as the base material, weight can be reduced and manufacturing costs can be reduced. However, in the case of those using plastic as a base, there has been no one that satisfies the durability as a magnetic recording medium.

[Purpose of the invention]

In view of these circumstances, the present invention provides a magnetic recording medium that has a plastic base and has excellent durability.

The purpose is to provide the body.

[Disclosure of the invention]

In order to achieve such an object, the present invention provides a magnetic recording medium in which a plating base film, a nonmagnetic metal plating layer, a magnetic material film, and a lubricating protective film are laminated in this order on the surface of a plastic substrate. The plating base film is formed by laminating a plurality of base thin films, and among these base thin films, the thin film in contact with the plastic base is formed of a material that has good adhesion to the plastic base, and The gist of the present invention is a magnetic recording medium characterized in that a thin film in contact with a non-magnetic metal plating layer is formed of a material that has good adhesion to the non-magnetic metal plating layer.

Hereinafter, embodiments of the present invention will be explained in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional side view of one embodiment of the magnetic recording medium according to the present invention. As shown in the figure, this magnetic recording medium has a plating base film 2 on both sides of a plastic substrate 1. Non-magnetic metal plating Pt3. Magnetic film 4. The lubricating protective film 5 is laminated in this order.

The material forming the plastic base 1 is preferably an amorphous polymer, such as polymethyl methacrylate resin or polycarbonate resin.

Polysulfone resin, polyethersulfone resin.

Examples include polystyrene resin, polyetherimide resin, polyphenylene oxide resin, etc., and these may be used alone or in combination. An inorganic substance that softens at the temperature during molding of these resins.

Compounds such as metals may be included as necessary. Examples of the inorganic substance include sodium thiocyanate, and examples of the metal include solder.

Plastic substrate 1 from these resins or resin mixtures
Methods for obtaining this include, but are not particularly limited to, a method of punching a sheet-like product obtained by extrusion molding into a predetermined size, a method of performing injection molding using a mirror-finished mold, etc. .

The plating base film 2 is a non-magnetic film that serves as a base when a non-magnetic metal plating layer is formed by plating, and does not have good adhesion to both the plastic substrate 1 and the non-magnetic metal plating layer 3. must not.

Therefore, in the magnetic recording medium of this embodiment, the plating base film 2 is disposed on the side in contact with the plastic base 1, and the first base thin film 1 has good adhesion to the plastic base 1! J2a and
It is formed by laminating two thin films, the non-magnetic gold mud plating layer 3 which is placed on the side in contact with the non-magnetic metal plating layer 3, and the second base thin film 2b which has good adhesion. In other words, the reason why the plating base film 2 is formed of a plurality of thin films as described above is because the plating base film 2 is made of one type of material and has good adhesion to both the plastic substrate 1 and the non-magnetic metal plating layer 3. This is because the geological membrane 2 cannot be formed.

The first base thin film 2a is selected from a film that has good adhesion to the plastic substrate 1, such as Zn, Cr, Ti, etc.
Examples include thin films such as metals such as AlN, SiN, TiN, and nitride ceramics. The second base thin film 2b is not particularly limited as long as it has good adhesion to the nonmagnetic metal plating layer 3, but for example, A
u, A'g, Pt, Cu.

Examples include thin films of nonmagnetic metals such as At, Pd, and Pb.

Among these, Cu and Pd are preferred because they have particularly good adhesion to the nonmagnetic metal plating layer 3.

The above-mentioned first base thin film 2a and second base thin film 2b are formed by methods such as vapor deposition, ion blasting, and sputtering in the case of metal, and by ion blasting, sputtering, and plasma CVD in the case of nitride ceramic.
It is formed by the following methods. Further, the surface of the plastic substrate 1 may be subjected to plasma etching, reverse sputtering, etc. before forming the first base thin film 2a. In this way, the adhesion to the plastic substrate 1 can be further improved.

When Cu is used as the second base thin film 2b, the thickness of the film is preferably about 0.1 to 2.0 μm. 0.
If it is less than 1 μm, the adhesion of plating in the next step will be poor. If it exceeds 2.0 μm, cracks will occur in the film, and the hendoklassochastic resistance (hereinafter referred to as "C8S resistance") will not improve. The thickness of the film when using Pd is 50 to 20
00 people is preferable. If there are fewer than 50 people, many pinholes will occur in the film, resulting in poor plating adhesion in the next step. If the number exceeds 2000, cracks will occur in the film and CSS resistance will not improve.

The nonmagnetic metal plating layer 3 serves as a base for the magnetic film 4 and is formed to increase the surface hardness of the plastic substrate 1. By increasing the surface hardness, the plastic base 1 is prevented from being deformed even if the magnetic head comes into contact with a magnetic recording medium during use. In other words, the nonmagnetic metal plating layer 3 is provided to improve C8S resistance.

The non-magnetic metal plating layer 3 is not particularly limited as long as it has corrosion resistance and has a surface hardness (v) of 300 or more, but a non-magnetic electroless nickel-based plating layer is preferable. Electroless nickel The composition of the system plating layer is:
From the viewpoint of non-magnetic stability, N1-P, N1-Cu-P, etc. are preferred. The thickness of the plating layer is preferably about 10 to 30 μm. 10. If the temperature is less than am, the surface hardness does not become so high because the base body has elasticity. Therefore, C8S resistance is poor. If it exceeds 30 μm, the plastic substrate 1 itself will warp due to the internal stress of the plating layer, so that the C8S resistance will not improve.

The material of the magnetic film 4 is T-Fe, Q, etc.

Barium ferrite magnetic powder, Co-N1-P.

Examples include Co-Ni-Cr alloy, Co-Cr alloy, and iron oxide alloy. The method of forming these magnetic films 4 is not particularly limited. For example, γ-Fezes,
When forming the magnetic film 4 using barium ferrite magnetic powder, these powders are dispersed in a binder,
Do it by spin code. Co Ni
When forming PFi, electroless plating is used. In the case of any layer of Co-Ni-Cr alloy, Co-Cr alloy, and iron oxide alloy,
This is done by sputtering or the like.

The magnetic film 4 may be a single layer or a multilayer, if necessary. Note that before forming the magnetic film 4, the surface of the non-magnetic metal plating layer 3 may be mirror-finished or texture-finished by lapping, boring, etc., if necessary.

The lubricating protective film 5 is not particularly limited, but may be formed of carbon or the like, for example. The method for forming the lubricating protective film 5 is not particularly limited, and examples include sputtering and the like.

Next, examples will be described in detail together with comparative examples.

(Example 1) A mold with a highly precise smooth surface for injection molding is prepared, and this mold is used to inject polyetherimide resin (product name: Ultem 1).
000-1000) was obtained. A plating base film of 300% was applied as the first base thin film on both sides of this substrate.
AI film with a thickness of 0 and 4000 as the second base thin film
A human-thick Ag film was laminated using a high-frequency sputtering device. Note that AI with a purity of 99.9% and Ag with a purity of 99.5% were used as targets, respectively.

Next, this is immersed in an electroless N1-P plating bath (product name: Nimden HDX manufactured by Kamiza Kogyo@) at 90°C for 60 minutes to form a 28 μm thick N1-P plating layer as a non-magnetic metal plating layer. did. This was subjected to a double-sided polishing machine to finish the surface roughness of the plating layer to 0.004 μm.

The thickness of the plated layer after finishing was 25 μm. Thereafter, a Cr film with a thickness of 2500 mm was formed as a magnetic property improving film using a high frequency sputtering device. The purity of Cr used as a target was 99.5%. A further ferromagnetic metal film of Co is formed on this Cr film.
-A Ni-Cr alloy film was formed to a thickness of 700 mm. The Co-Ni-Cr alloy used as the target had a purity of 99.9%, of which the Ni content was 30-t%,
The Cr content was 7.54%. Furthermore, on top of that,
A magnetic recording medium was obtained by forming a carbon film with a thickness of 350 mm as a lubricating protective film. The carbon used as a target had a purity of 99.99%.

(Example 2) The substrate was formed of polysulfone resin, and a 2000 Ti film was used as the first underlayer thin film, and a 3000 nm Ti film was used as the second underlayer thin film.
Except that an Au film of 0.0000 was formed and the thickness of the Ni'-P plating layer (thickness after polishing) was 30 μm.
A magnetic recording medium was obtained in the same manner as in Example 1.

(Example 3) The base was formed of polycarbonate resin, a 1000-layer Cr film was formed as the first underlayer thin film, a 5000-layer Cu film was formed as the second underlayer thin film, and the thickness of the N1-P plating layer (polishing A magnetic recording medium was obtained in the same manner as in Example 1, except that the thickness (later thickness) was 20 μm.

(Example 4) The base was formed of polyether sulfone resin, and the first
Example 1 except that a 1,200-layer SiN film was formed as the base thin film, a 2,000-layer Ag film was formed as the second base thin film, and the thickness of the N1-P plating layer (thickness after polishing) was 22 μm. A magnetic recording medium was obtained in the same manner.

(Example 5) The base was formed of polycarbonate resin, a TiN film of 2000 nm was formed as the first underlayer thin film, a Pd film of 1000 nm was formed as the second underlayer thin film, and the thickness of the N1-P plating layer (polishing A magnetic recording medium was obtained in the same manner as in Example 1, except that the thickness (later thickness) was 18 μm.

(Example 6) The base was formed of polyetherimide resin, a 1500-layer AIN film was formed as the first base thin film, a 3000-layer Cu film was formed as the second base thin film, and the thickness of the N1-P plating layer was A magnetic recording medium was obtained in the same manner as in Example 1 except that the thickness (thickness after polishing) was 25 μm.

(Example 7) The base was formed of polycarbonate resin, a Cr film of 2,000 yen was formed as the first underlayer thin film, a Pd film of 1,000 yen was formed as the second underlayer thin film, and the thickness of the N1-P plating layer (polishing A magnetic recording medium was obtained in the same manner as in Example 1, except that the thickness (later thickness) was 20 μm.

(Example 8) The substrate was formed of polysulfone resin, the first base thin film was a Ti film of 2,000 mm, and the second base thin film was a Ti film of 30 mm.
A magnetic recording medium was obtained in the same manner as in Example 1, except that an Au film of 0.000 mm was formed and the thickness of the N1-P plating layer (thickness after polishing) was set to 30 μm.

(Comparative Example 1) The substrate was formed of polyetherimide resin, only a 3000 Cu film was formed as a plating base film, and
The thickness of the N1-P plating layer (thickness after boring) is 35
A magnetic recording medium was obtained in the same manner as in Example 1 except that the thickness was μm.

(Comparative Example 2) The substrate was formed of polycarbonate resin, only a Pd film of 1000 was formed as a plating base film, and N
1-The thickness of the P plating layer (thickness after polishing) is 18μ
A magnetic recording medium was obtained in the same manner as in Example 1 except that m was used.

(Comparative Example 3) A magnetic recording medium was obtained in the same manner as in Example 1, except that the substrate was formed of polyether sulfone and a magnetic film was directly formed without forming a base film or a metal plating layer. .

A magnetic head was attached to the magnetic recording media obtained in Examples 1 to 8 and Comparative Examples 1 to 3 above, and CSS resistance was examined.

The results are shown in Table 1. Note that CSS resistance refers to the number of times a magnetic head contacts the surface of a magnetic recording medium rotating at a high speed of 3600 rpm until the medium or head is damaged. There is.

As shown in Table 1, those of Examples 1 to 8 are the same as those of Comparative Example 1.
All of them have excellent CSS resistance compared to those of Nos. 3 to 3. That is, the magnetic recording medium according to the present invention, which has excellent durability, is not limited to the above embodiments. for example,
In the above embodiment, the plating base film was formed of two layers, the first base thin film and the second base thin film, but a base thin film with good adhesion to the base thin film was placed on the plastic base 1 side, and the non-magnetic metal plating N3 If a base thin film with good adhesion is placed on the side, another thin film may be formed between these base thin films. That is, the base thin film forming the plating base film 2 may have three or more layers as necessary. In the above embodiments, the films and layers were formed on both sides of the substrate, but they may be formed on one side. The nonmagnetic metal plating layer and the magnetic film may be formed by electroplating.

〔Effect of the invention〕

As described above, the magnetic recording medium according to the present invention is a magnetic recording medium in which a plating base film, a nonmagnetic metal plating layer, a magnetic film, and a lubricating protective film are laminated in this order on the surface of a plastic substrate. The plating base film is formed by laminating a plurality of base thin films, and among these base thin films, the thin film in contact with the plastic base is formed of a material that has good adhesion to the plastic base, and the non-magnetic metal Since the thin film in contact with the plating layer is made of a material that has good adhesion to the non-magnetic metal plating layer, it is lightweight and has excellent durability. Moreover, it can be manufactured at low cost.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of one embodiment of a magnetic recording medium according to the present invention. 1...Plastic base 2...Plating base film 3
...Nonmagnetic metal plating layer 4...Magnetic film 5...
- Lubricating protective film 2a...First base thin film 2b...Second base thin film Agent Patent attorney Takeshi Matsumoto Hikote U Mikiho (Sponsored by September 14, 1988 Patent Application No. 119390) 2. Name of the invention 3. Relationship with the person making the amendment Patent applicant Address 1048 Kadoma, Kadoma City, Osaka Name (583) Representative of Matsushita Electric Works Co., Ltd. 4 Sadao Fujii, the role of Kaiteng 4, No agent 6, Specification subject to amendment 7, Contents of amendment (1) From page 10, line 6 to line 7 of the specification, “60
Correct the text "minutes" to "4 hours." (2) “Polycarbonate” on page 11, line 12 of the specification
Correct the statement to "polyetherimide". (3) On page 13, line 8 of the specification, the statement "r2,000 people" should be corrected to "rlo00 people."

Claims (1)

[Claims] (1) A magnetic recording medium in which a plating base film, a nonmagnetic metal plating layer, a magnetic film, and a lubricating protective film are laminated in this order on the surface of a plastic substrate, wherein the plating base film is a plurality of base thin films. are formed by laminating them, and among these underlying thin films, the thin film in contact with the plastic base is formed of a material that has good adhesion to the plastic base,
A magnetic recording medium characterized in that a thin film in contact with the non-magnetic metal plating layer is formed of a material that has good adhesion to the non-magnetic metal plating layer.