JPH035915A - Substrate for magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To obtain a cheap substrate for magnetic recording medium comprising synthetic resin with high surface hardness and having excellent heat resistance and adhesion property by forming a metal ion implantation layer by implanting metal ions in the surface area of the synthetic resin substrate and then forming an aluminum anodizing film on the metal ion injection layer. CONSTITUTION:Metal ions are implanted in a synthetic resin substrate 1 on which an alumite film 3 is formed by anodizing an Al layer formed on the substrate 1. By this method, the alumite film 3 can be formed with good adhesion on the substrate 1. Surface hardness of the alumite film 3 can be further improved by filling fine pores in the film 3 with nonmagnetic metal 4. Thus, the obtd. medium is light and has excellent reliability and good productivity.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a substrate for magnetic recording media, and more specifically,
The present invention relates to a magnetic recording medium substrate formed by forming an aluminum anodic oxide film on the surface of a synthetic resin substrate.

[Prior Art] In recent years, studies have been made to use synthetic resin substrates as substrates for magnetic recording media. Synthetic resin substrates are lighter than aluminum alloy substrates, more resistant to impact, and easier to process. Furthermore, in the case of synthetic resin substrates, attempts have been made to form a highly hard coating on the surface of the substrate in order to improve the hardness of the substrate surface and obtain sufficient CSS characteristics and scratch resistance. Conventionally, the following types of synthetic resin substrates having a highly hard coating formed on their surfaces have been known, for example.

■Technology disclosed in Japanese Unexamined Patent Publication No. 59-213025 This uses a mixed composition of ABS resin and/or MBS resin and polycarbonate resin as the synthetic resin forming the substrate, and an alloy containing N1-P as the main component. A film is formed on the synthetic resin substrate by a wet plating method.

That is, by using a mixed composition of ABS resin or the like and polycarbonate resin as the synthetic resin that forms the substrate, the N1-P alloy coating, which has been known for a long time as a coating for improving the surface hardness of aluminum alloy substrates, can be used. This makes it possible to use it as a surface coating.

The alloy film containing N1-P as a main component has characteristics such as being highly hard and non-magnetic, and being wet-plated with excellent mass productivity.

(2) Technique disclosed in Japanese Patent Application Laid-open No. 187117/1983 This technique forms a film of Ti or a Ti compound on the surface of a synthetic resin substrate using an ion blasting method. Such a method can also improve the hardness and roughness of the substrate surface.

[Problems to be Solved by the Invention] However, the conventional magnetic recording medium substrates described above have the following problems:
The following issues were encountered.

■The technology disclosed in Japanese Patent Application Laid-Open No. 59-213025 has a technique in which the resin used for forming the substrate is ABS resin and/or
Alternatively, since the composition is limited to a mixed composition of MBS resin and polycarbonate resin, there is a problem in that the use of resins with better moldability or resins with better heat resistance is restricted.

In addition, when ABS resin is mixed as a substrate raw material, the heat resistance of the substrate decreases, so there is a problem that it is difficult to use a method that requires heat resistance such as sputtering when forming a recording film. .

Furthermore, in this magnetic recording medium substrate, the surface of the substrate is roughened during the formation of the plating layer to improve the adhesion between the substrate and the plating layer, but the adhesion obtained by this method is insufficient for magnetic recording. It could not be said that it was sufficient for practical use as a medium, and improvements in its rationality were desired.

■The technology shown in JP-A No. 61-187117 requires the formation of a Ti or Ti compound coating of several micrometers in order to obtain the necessary hardness when used as a magnetic recording medium. Forming a film using the ion blasting method requires a very long time, which poses a problem in that it causes high costs. Furthermore, there is also a problem in that the resin magnetic recording substrate suffers from a great deal of thermal damage during film formation, which causes deformation of the substrate.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a synthetic resin substrate for a magnetic recording medium that is excellent in heat resistance and adhesion and has high surface hardness at a low cost.

[Means for Solving the Problems] A first aspect of the present invention is a substrate for a magnetic recording medium comprising at least an anodic oxide film of aluminum formed on a synthetic resin substrate, the substrate being made of a synthetic resin. A substrate for a magnetic recording medium, characterized in that a metal ion implantation layer is formed by implanting at least one type of metal ion near the surface, and the anodic oxide film of aluminum is formed on the metal ion implantation layer. exist.

A second aspect of the present invention is a substrate for a 6N recording medium, which is formed by forming at least an anodic oxide film of aluminum on a synthetic resin substrate, the synthetic resin substrate having at least one type of substrate near the surface thereof. Metal ions are implanted to form a metal ion implanted layer, and on the metal ion implanted layer, the aluminum anodic oxide film having a large number of micropores is formed on the surface, and a nonmagnetic metal or alloy is formed in the micropores. exists in a magnetic recording medium substrate characterized by being filled with.

Hereinafter, the configuration of the present invention will be explained in detail.

(Synthetic resin substrate) As the synthetic resin substrate used in the present invention, for example, one formed of one or a mixture of two or more resins such as acrylic, polycarbonate, polyimide, and epoxy resins can be used. be. It may also contain fillers such as glass fibers and alumina particles.

(Injection of metal ions) In the present invention, ions are implanted into the synthetic resin substrate.

Ion implantation is performed at I x 10-5 Torr to I x 1
It is preferable to perform this under a vacuum of about 0-' Torr.

The ion species to be implanted may be any metal as long as it can be ionized, but it is preferable to use a nonmagnetic metal. This is to avoid impairing the magnetic recording and reproducing characteristics when a magnetic recording medium formed using the magnetic recording medium substrate of the present invention is actually used. Furthermore, since an anodic oxidation method is used when forming the alumite layer in the process described below, it is preferable to implant ionic species that are less likely to contaminate the bath.

AJ! is an ionic species that rarely pollutes the bath. ,
Examples include Cu.

The acceleration voltage during ion implantation is preferably within the range of 10 kV to IOMV. This is because if it is less than 10 kV, the energy given to the ions is too small to perform sufficient ion implantation, and if it is more than IOMV, the ion implanted surface becomes brittle and the adhesion with the alumite coating decreases. It is from. The ion implantation amount under these conditions is 1()13 ions/cm2 to 1o20 ions/C
It is preferably within the range of m2.

The thickness of the ion implantation layer formed by ion implantation is 5
The number is preferably within the range of 00 to 10,000 people. This is because the desired performance (surface hardness, CS
S characteristics, etc.) are not exhibited, and even if the performance is exceeded by too many people, not only will the performance not improve any further, but on the contrary, productivity will deteriorate.

(Positive Oxidation of Aluminum III) Next, in the present invention, positive oxidation of aluminum 11i (alumite film) is formed on the synthetic resin substrate into which ions have been implanted. The alumite coating is obtained by anodizing the A2 layer formed by vacuum evaporation or the like.

The thickness of the alumite coating is preferably 2 μm to 20 μm. This is because if the thickness is less than 2 μm, the desired performance (surface hardness, CSS properties, adhesion with alumite film, etc.) cannot be achieved, and if it exceeds 20 μm, not only will the performance not improve any further, but productivity will actually deteriorate. .

When an alumite film is formed by anodizing the A1 layer formed by a vacuum evaporation method or the like, fine pores perpendicular to the film surface are obtained in the alumite film. Zn and Ti are contained in these micropores.

An even stronger coating can be obtained by electrolytically depositing a non-magnetic, highly hard metal such as a Ni--Cu alloy.

Furthermore, by selectively etching only the alumite part of the alumite coating, which is made by electrolytically depositing a non-magnetic and highly hard metal, using an acid within the range of 50 to 1000 people.
Fine irregularities can be provided on the surface of the alumite coating. As a result, the surface of the alumite coating can be appropriately roughened, and a substrate for a magnetic recording medium that is excellent in C5S resistance and is less likely to be attracted to a magnetic head can be obtained. The reason why the etching amount is set in the range of 50 to 1000 is that if it is less than 50 Å, no effect of preventing magnetic head adsorption can be obtained, and if it is more than 100 Å, the recording performance will be adversely affected.

[Function] According to the present invention, since metal ions are implanted into the surface of the substrate formed of synthetic resin, an alunite film can be formed with good adhesion on the surface of the substrate. That is,
It becomes possible to obtain a magnetic recording medium substrate having a highly hard surface coating with excellent adhesion. Furthermore, since excessive heat is not generated during ion implantation, problems such as thermal deformation of the synthetic resin substrate do not occur.

Furthermore, by filling the micropores in the alumite film with a nonmagnetic metal, the surface hardness of the alumite film can be roughly improved.

Furthermore, by providing fine irregularities through selective etching, the surface of the alumite coating can be appropriately roughened, providing a substrate for magnetic recording media that has excellent C3S resistance and is less prone to adsorption with magnetic heads. It becomes possible to do so.

Hereinafter, the present invention will be explained in more detail.

The present inventor developed a method of forming an alloy thin film containing N1-P as the main component on a synthetic resin substrate in order to obtain a synthetic resin magnetic recording medium substrate with excellent heat resistance and adhesion and high surface hardness. Instead, we investigated how to apply another method, which has been conventionally used to improve the surface hardness of aluminum alloy substrates for magnetic recording media, to synthetic resin substrates.

Conventionally, methods for improving the surface hardness of aluminum alloy substrates include forming an alloy thin film containing N1-P as the main component on the surface of the substrate, as well as attempts to alumite the surface of the substrate, and An attempt has been made to fill a large number of micropores formed when the surface of the substrate is alumitized with a nonmagnetic metal. These methods are based on the N1
-It has the characteristics of higher surface hardness and superior smoothness than the P alloy coating.

'Therefore, as a result of intensive study on how to apply these techniques to synthetic resin substrates, the inventor of the present invention formed a thin aluminum film on a synthetic resin substrate, anodized this aluminum thin film, or applied it to the alumitized portion. We came up with the idea that the above technology could be applied to synthetic resin substrates by providing a large number of micropores and filling these micropores with nonmagnetic metal.

However, when the present inventor tried such a substrate for magnetic recording media, the adhesion between the alumite coating and the synthetic resin substrate was poor, as was the case with the alloy thin film containing N1-P as the main component, making it impractical for actual use. It was unbearable.

Therefore, the inventor of the present invention conducted further studies on a method for improving the adhesion between the alumite coating and the synthetic resin substrate, and as a result, the inventor injected metal ions in advance into the surface of the substrate formed of synthetic resin, and then It was discovered that by forming an aluminum thin film on a resin substrate and anodizing this aluminum thin film, it is possible to improve the adhesion between the synthetic resin substrate and the alumite coating, which led to the present invention. It is.

[Example] Hereinafter, one example of the present invention will be described. In this example, as an example of a magnetic recording medium substrate, 6
The case of the 11-speed disk substrate will be explained.

FIG. 1 is a schematic cross-sectional view showing a magnetic disk substrate according to this embodiment. In the figure, 1 is a polyetherimide substrate as a synthetic resin substrate, 2 is a metal ion implantation layer of the synthetic resin substrate (Aj2 ions were used as metal ions), 3 is an alumite coating, and 4 is a nonmagnetic metal. It is Sn.

The magnetic disk substrate according to this example was manufactured as follows.

■A polyetherimide substrate was produced by injection molding.

(2) A.degree. C. ions were implanted into this substrate using an ion implantation device to form an ion implantation layer with a thickness of 5,000 layers.

The implantation of A1 ions was carried out under a vacuum of 1×10'' Torr and an accelerating voltage of 800 kV, and the implantation amount was 101
51 pieces/cm'.

(2) An Aj2 film having a thickness of 110A1 was formed on this substrate using a vacuum evaporation method.

■Next, Afl on the board? r1. Regarding II!g, in a 3 wt% oxalic acid solution under conditions of an electrolytic voltage of 50 vti and a temperature of 25°C, II! Polar oxidation treatment was performed.

■Finally, electrolytic deposition of Sn was performed on this substrate in a sulfate solution at a temperature of 50°C, and Sn was deposited in the micropores created during the anodizing process.
filled with.

Through the above steps, a magnetic disk substrate according to this example was obtained.

As a result of measuring the surface hardness of the thus obtained magnetic disk substrate by the micro-Vickers method, it was found that the load was 25 g.
It was 800.

Next, the adhesion strength of the alumite coating of the magnetic disk substrate according to this example was evaluated using the JIS H8504 crease line test method and peel test method (tape test method - 2 mm stripes on each side). For comparison, the same procedure was also applied to a magnetic disk substrate on which an alumite film was formed without ion implantation (i.e., a magnetic disk substrate created without going through the above step ①, with all other conditions being the same). We conducted an evaluation. These results are shown in Table 1.

As is clear from Table 1, the alumite coating of the magnetic recording medium substrate of this example did not peel off at all, and its adhesion strength was found to be extremely excellent. Although the case of a magnetic disk substrate has been explained as an example of such a magnetic recording medium substrate, similar results were obtained with substrates used for other magnetic recording media.

[Effects of the Invention] As explained above, according to the present invention, it is possible to form a highly hard alumite film with excellent adhesion on the surface of a synthetic resin substrate, which is lightweight, highly reliable, and easy to mass produce. It becomes possible to provide a magnetic recording medium substrate with good quality.

Further, by providing fine irregularities by selective etching, it is possible to provide a substrate for a magnetic recording medium that has excellent C8S resistance and is less likely to be attracted to a 1IF air head.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing a magnetic disk substrate according to this embodiment. Fig. 1 1... Polyetherimide substrate as a synthetic resin substrate, 2... Metal ion implantation layer of synthetic resin substrate, 3...
- Alumite coating, 4...Sn as a nonmagnetic metal.

Claims (5)

[Claims] (1) A magnetic recording medium substrate formed by forming at least an anodic oxide film of aluminum on a synthetic resin substrate, wherein at least one or more metal ions are implanted near the surface of the synthetic resin substrate to form a metal 1. A substrate for a magnetic recording medium, characterized in that an ion implantation layer is formed, and the aluminum anodic oxide film is formed on the metal ion implantation layer. (2) A magnetic recording medium substrate formed by forming at least an anodic oxide film of aluminum on a synthetic resin substrate, wherein at least one or more metal ions are implanted near the surface of the synthetic resin substrate to form a metal An ion-implanted layer is formed, the aluminum anodic oxide film having a large number of micropores on the surface is formed on the metal ion-implanted layer, and the micropores are filled with a non-magnetic metal or alloy. A substrate for magnetic recording media. (3) The magnetic recording medium substrate according to claim 2, wherein the nonmagnetic metal or alloy filled in the micropores protrudes from the surface of the aluminum anodic oxide film. (4) After filling the fine pores of the anodic oxide film of aluminum with a metal or alloy, selectively etching only the anodic oxide film of aluminum allows the anodic oxide film to be removed from the anodic oxide film of aluminum. 4. The method of manufacturing a magnetic recording medium substrate according to claim 3, further comprising forming protrusions of magnetic metal or alloy. (5) The magnetic recording medium substrate according to claim 1 or 2, wherein the metal ions injected into the synthetic resin substrate are nonmagnetic metal ions.