JP2741380B2 - Manufacturing method of magnetic recording medium - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium used for a magnetic disk drive, and more particularly to a CSS (contact start and
Stop) The present invention relates to a magnetic recording medium for improving durability.

[Prior art] Conventionally, as a magnetic recording medium of this type, a magnetic layer is formed on a substrate made of an aluminum alloy, and then a solution containing silica fine particles and organosilicon is formed on the magnetic layer. In some cases, a thin film (protective film) containing silica particles was laminated on a base material made of SiO ₂ by coating and heat treatment (see, for example, JP-A-61-229227. "). In addition, a magnetic layer, a protective film, and the like are sequentially laminated on a glass substrate, and the surface on which the magnetic layer of the glass substrate is laminated is scratched with particles of Al ₂ O ₃ or the like to form irregularities. There was a recording medium (hereinafter referred to as “prior art 2”).

[Problems to be solved by the invention]

However, according to the magnetic recording medium according to the prior art 1, since fine particles are scattered in the base material of the protective film, in order to sufficiently increase the CSS durability and reduce the friction coefficient with the magnetic head, It is necessary to increase the size of the unevenness on the surface of the protective film. To this end, it is conceivable to increase the thickness of the protective film. However, as the thickness of the protective film increases, the distance between the magnetic head and the magnetic layer increases.
For example, there is a problem that the output at the time of reproducing information is reduced. Therefore, the thickness of the protective film is limited. Further, in the prior art 1, since the above-described solution is applied and heated in order to form a protective film after the formation of the magnetic layer, the magnetic layer may be oxidized by the heat treatment. There is a problem that the oxidation significantly deteriorates magnetic characteristics (for example, coercive force and residual magnetic flux density). further,
In the prior art 1, since the substrate is made of an aluminum alloy, impurities (for example, Al ₂ O ₃ , MgO, SiO ₂ , Al—Mg—O, etc. and Al—S
A missing pulse or an extra pulse is generated due to an intermetallic compound such as i-Fe, and the modulation characteristics are deteriorated.

In the magnetic recording medium of the prior art 2, since the surface can be polished with high precision, there is no problem caused by the material of the substrate as in the prior art 1, but particles such as Al ₂ O ₃ are used. If the surface of the substrate is scratched to form irregularities, it is difficult to control the depth of the concave portions and the height of the convex portions to several thousand mm each because the size of the particles is several μm. There is a problem that becomes unsuitable for.

[Means for solving the problem]

The present invention has been made to solve the above-described problems, and a method for manufacturing a magnetic recording medium of the present invention uses a solution containing fine particles and organosilicon or an organometallic compound on the main surface of a glass substrate. Forming a preliminary thin film, heat-treating the preliminary thin film, forming a thin film containing the fine particles in a base material, and chemically strengthening the glass substrate by an ion exchange method, and a magnetic layer on the thin film. And a step of sequentially laminating a protective layer and a lubricating layer.

[Action]

Further, according to the method of manufacturing a magnetic recording medium of the present invention, before forming the magnetic layer, a preliminary thin film is formed using the above-described solution and heat-treated to form the thin film. Further, since the substrate is chemically strengthened by the ion exchange method together with the heat treatment, the strength of the substrate is also improved.
Further, there is no need to form irregularities on the glass substrate itself with particles such as Al ₂ O ₃ .

Embodiment 1 A magnetic recording medium of the present embodiment and a method of manufacturing the same will be described below in detail with reference to FIG. This figure is a partial sectional view.

First, the opposite main surfaces were precisely polished, made of soda lime glass, outer diameter 130 mmφ, center hole diameter 40 mmφ,
A disk-shaped glass substrate 1 having a thickness of 1.9 mm is prepared. next,
This glass substrate 1 was treated with an organometallic compound of triethoxyaluminum, water, methanol, acetic acid and an average particle size of 10
Fine particles comprising alumina of 0 to 200 mm in a weight ratio of 1: 2:
The glass substrate 1 is immersed (about 1 minute) in a solution mixed at a ratio of 100: 0.01: 0.0001. Next, the glass substrate 1
Is gradually pulled up from the above-mentioned solution (about 20 cm / min) and taken out, and a preliminary thin film made of an organoaluminum compound containing alumina particles is applied to both main surfaces of the glass substrate 1, and about 60 ° C. in air at about 300 ° C. Then, a thin film 2 (thickness: about 100 to 300 °) containing alumina particles 21 in a base material made of aluminum oxide and having irregularities on the surface is formed. In the figure, the thin film 2 is shown only on one main surface, and the other is omitted. The same applies to the underlayer 3, the magnetic layer 4, the protective layer 5, and the lubricating layer 6, which will be described later.
Next, the glass substrate 1 on which the thin film 2 was laminated was placed in a DC magnetron sputtering apparatus, and a Cr target was used.
Under the conditions described above, a thickness of approximately
An underlayer 3 made of 2000 mm of Cr is laminated on the thin film 2. Next, the magnetic layer 4 made of CoNiCr having a thickness of about 700 mm is formed on the underlayer 3 in the same manner using a target made of CoNiCr.
Laminated on top, using a target made of C, thickness about 30
A protective layer 5 made of 0 ° C is laminated on the magnetic layer 4. Next, the glass substrate 1 laminated up to the protective layer 5 is taken out of the DC magnetron sputtering apparatus, and a fluorocarbon-based lubricant (fluorinated oil, for example, FONPRIN AM2001 manufactured by MONTEDISON) is applied onto the protective film 5 by spin coating. Apply to form lubricant 6 (thickness about 30mm)
The magnetic recording medium 7 is manufactured.

As shown in FIG. 1, the magnetic recording medium 7 of the present embodiment has a thin film 2
Of the surface of the base layer 3, the magnetic layer 4, the protective layer 5, and the lubricating layer 6, affect the respective surfaces of the base layer 3, the magnetic layer 4, the protective layer 5, and the lubricating layer 6, so that the surface of each layer (film) has irregularities. Therefore, prior art 1
No fine particles are mixed in the protective film layer as in the magnetic recording medium of (1).

Various characteristics of the magnetic recording medium 7 of this example are shown below. In addition,
The CSS durability was measured by pressing a magnetic head having an Al ₂ O ₃ —TiC sintered body in the slider portion against the magnetic recording medium 7 with a load of 15 g. The coefficient of friction was measured with the same magnetic head as that used for CSS durability.

Missing pulse: 0 Extra pulse: 0 Positive modulation: 0 Negative modulation: 0 Defect tracks: 0 CSS durability: 20,000 times or more Initial friction coefficient: 0.2 CSS Friction coefficient after 10,000 times: 0.4 Rotation speed : 27000rpm As described above, according to the magnetic recording medium 7 of this example, the thin film 2
Since the surface of the lubricating layer 6 becomes uneven due to the unevenness of the
S durability and friction coefficient were good values, and other characteristics were also good values depending on the glass substrate and the like.

Embodiment 2 A magnetic recording medium of the present embodiment and a method of manufacturing the same will be described in detail with reference to FIG. This figure is also a partial cross-sectional view, and the layers (films) to be laminated are also shown only on one main surface of the glass substrate as in the above embodiment.

First, a glass substrate 10 similar to that of the above example was prepared, and a weight ratio of tetraxysilane, which is organosilicon, water, isopropyl alcohol, acetic acid, and fine particles made of silica having an average particle diameter of about 100 to 200 ° was 1: 2. A solution mixed at a ratio of: 50: 0.01: 0.001 is applied to both main surfaces of the glass substrate 10 by spin coating to form a preliminary thin film layer made of an organosilicon compound containing silica particles. Next, the glass substrate 10 coated with this thin film is preheated in the air at a temperature of about 300 ° C. for 30 minutes, and then immersed in a potassium nitrate solution at about 400 ° C. for 8 hours, and a glass substrate made of soda lime glass is formed.
10 is ion-exchanged for chemical strengthening. In the process from the preheating to the chemical strengthening, the above-mentioned thin film is a thin film 1 containing silica particles 111 in a base material made of silicon oxide.
1 (film thickness of about 100 to 400 mm). Next, a magnetic layer 12 of CoNiPt (with a film thickness of about 700
1), an intermediate layer 13 (about 100 mm thick) made of Cr is sequentially laminated on the thin film 11 using Cr as a target. Next, Ar gas 2
0 mTorr, RF power 1 kW, using a target made of SiO ₂ and using a high-frequency magnetron sputtering method, a thickness of about 200
A protective film 14 made of SiO ₂ is laminated on the intermediate layer 13. Next, for example, KRYT manufactured by DuPont
A fluorinated oil composed of OX157FSH is applied on the protective film 14 and a lubricating layer 15 having a thickness of 30 mm is laminated, thereby producing a magnetic recording medium 16.

The magnetic recording medium 16 of the present embodiment also has the protective film 14 as in the previous embodiment.
Irregularities are formed on the surface of the magnetic recording medium 16 so that fine particles are not mixed therein.

The characteristics of the magnetic recording medium 16 of this example are shown below. In addition,
The methods for measuring the CSS durability and the coefficient of friction are the same as those in the above-described embodiment.

Missing pulse: 0 Extra pulse: 0 Positive modulation: 0 Negative modulation: 0 Defect track: 0 CSS durability: 20,000 times or more Initial friction coefficient: 0.2 CSS Friction coefficient after 10,000 times: 0.3 Rotational strength : 35000rpm As described above, according to the magnetic recording medium 16 of this example, the CSS
Not only the durability and the coefficient of friction but also other characteristics were good. In addition, the rotation strength is higher than that of the magnetic recording medium 7 of the above embodiment because of the chemical strengthening. Further, since the intermediate layer 13 made of Cr is laminated on the magnetic layer 13, the moisture resistance of the magnetic layer 12 is improved.

The present invention is not limited to the above embodiment, but may be the following. First, as the organometallic compound, in addition to triethoxyaluminum, methoxides such as Ti, Sn, Ta, W, Cr, Zn, Ce, Co, and Mg, and alkoxides such as ethoxide may be used, and fine particles may be silica or alumina. Other Si ₃ N ₄ , SiC, etc. may be used, or a mixture thereof. However, silica, alumina or a mixture of silica and alumina is very advantageous in production because it is easily available and inexpensive. The size of the fine particles is not limited to 100 to 400 mm,
If it is less than about 00 °, there is no practical problem because the flying stability of the magnetic head is not affected. Further, the base material of the thin film is not limited to silicon oxide or aluminum oxide, and may be made of the above-described metal oxide in the alkoxide. The thickness of this thin film is not limited to 100 to 400 mm and is not a practical problem. It may be thick to the extent that there is no problem. Also, a solution containing an organosilicon or an organometallic compound is filtered, and methanol,
In addition to isopropyl alcohol and acetic acid, other alcohols such as n-butanol, other acids such as hydrochloric acid, and a surfactant may be included. The application of the thin film may be a spray method other than the dipping method or the spin coating method. In addition, as the glass substrate, other glass such as aminosilicate glass, aluminoborosilicate glass, and quartz glass may be used in addition to soda lime glass. However, when chemically strengthening, it must be a glass containing Li ions or Na ions, such as soda lime glass.

Further, the underlayer, the magnetic layer, the protective film, and the lubricating layer are not limited to those in the above-described embodiment, but may be respectively an underlayer such as W, CoNi, CoNiCrPt.
, A protective film such as Si ₃ N ₄ , Al ₂ O _3, and a solid lubricating layer such as a steering wheel.

Further, a thin film containing fine particles, a magnetic layer, and the like may be laminated only on one main surface of the glass substrate.

〔The invention's effect〕

Since the present invention is configured as described above,
The following effects are obtained.

By providing a thin film containing fine particles in the base material between the glass substrate and the magnetic layer, it is not necessary to strictly control the film thickness of the thin film, and even if the thickness becomes thicker, the thin film is below the magnetic layer. Since the characteristics of the magnetic recording medium are not affected, not only the production becomes very easy, but also various methods such as a dipping method can be used as a thin film coating method.

By providing an underlayer between the glass substrate and the magnetic layer, the magnetic properties are improved.

Before forming the magnetic layer, a preliminary thin film is formed on the main surface of the glass substrate using a solution containing fine particles and organosilicon or an organometallic compound, and this thin film is subjected to heat treatment. And good magnetic properties can be obtained without oxidizing.

Further, since the glass substrate is chemically strengthened by the ion exchange method together with the heat treatment of the preliminary thin film described above, in the magnetic recording medium described in the prior art 1, the substrate is a glass substrate and the glass substrate is chemically strengthened. Can also simplify manufacturing. That is, the magnetic recording medium of the prior art 1 is a magnetic recording medium in which a magnetic layer and a protective film (a thin film containing fine particles) are sequentially laminated on a glass substrate.
Although the magnetic layer interferes and the glass substrate cannot be strengthened together with the heat treatment of the protective film, on the other hand, according to the present invention, ion exchange is performed immediately after the formation of the preliminary thin film. it can.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing one embodiment of the present invention, and FIG. 2 is a partial sectional view showing another embodiment of the present invention. 1,10: glass substrate, 2,11: thin film containing fine particles,
3 ... Underlayer, 4,12 ... Magnetic layer, 5,14 ... Protective film, 6,15
... lubricating layer, 7,16 ... magnetic recording medium, 21,111 ... fine particles.

Claims (1)

(57) [Claims] 1. A step of forming a preliminary thin film on a main surface of a glass substrate using a solution containing fine particles and an organic silicon or an organometallic compound, and heating the preliminary thin film to form a fine particle in a base material. A method for producing a magnetic recording medium, comprising the steps of: forming a thin film containing Si and chemically strengthening the glass substrate by an ion exchange method; and sequentially laminating a magnetic layer, a protective film, and a lubricating layer on the thin film. .