JPH05334667A - Production of magnetic disk and magnetic disk - Google Patents

Abstract

PURPOSE:To form a magnetic layer having prescribed rugged patterns on a disk substrate and to improve the flatness of the magnetic disk by decreasing the waving and distortion of the disk, and to improve mass productivity at the time of producing the magnetic disk. CONSTITUTION:The magnetic layer is formed on the rigid disk base body made of a resin and a disk body 5 is obtd. from the base body. The disk body 50 is held between a pair of pressurizing means 1 and 2 having the rugged patterns and is pressed nearly simultaneously with the obtaining of the disk body 50 or after the disk body 50 is obtd. The disk body 50 is heated before or during the pressing in such a case.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called hard type magnetic disk having a magnetic layer on a rigid substrate made of resin, and a magnetic disk.

[0002]

2. Description of the Related Art A magnetic disk drive used in a computer or the like uses a hard type magnetic disk in which a magnetic layer is formed on a rigid substrate. As a magnetic head for recording / reproducing on / from a hard type magnetic disk, various flying magnetic heads are used.

In recent years, the recording density of these magnetic disk devices has rapidly increased with the increase in capacity and size. Therefore, in the magnetic disk, the coercive force of the magnetic layer has been made higher, the layer has been made thinner, and the surface has been made smoother in order to cope with higher density. Is being reduced.

As the rigid substrate, a disc-shaped Al-based metal substrate is usually used. However, there is a demand for high-speed rotation for improving the transfer rate and recording density and miniaturization of the driving device. However, there is a strong demand for weight reduction and cost reduction of magnetic disks. Therefore, a magnetic disk using a resin-made rigid substrate, which is lighter than a metal substrate and is low in cost, is drawing attention.

However, the resin substrate has a poorer flatness than the disk substrate made of an aluminum alloy or glass, and it is difficult to reduce the flying height of the head because the surface deviation is large during the rotation of the substrate. It was said that it was not suitable for dense media. As means for solving these problems, Japanese Patent Laid-Open No. 1-23
Japanese Patent Laid-Open No. 7932 proposes a method for manufacturing a magnetic disk substrate in which a resin substrate is molded, the substrates are sandwiched between flat plates, heated, and pressure is applied between the flat plates to improve the flatness of the substrates. Finally, due to thermal strain in the process of forming the magnetic layer and internal stress of the magnetic layer, the flatness of the disk is finally deteriorated.

Further, a hard type magnetic disk is
A thin-film magnetic disk having a continuous thin-film magnetic layer formed by a vapor phase film forming method such as sputtering, and a magnetic coating material containing magnetic fine particles and a binder is applied, and then oriented.
There is a coating type magnetic disk having a coating type magnetic layer formed by curing or the like.

The coated magnetic disk is usually manufactured as follows.

First, a magnetic paint is applied on a disk substrate to orient it. Next, after the coating film is slightly cured, a polishing tape or the like is caused to act on the surface of the coating film to regulate the film thickness to a desired value and at the same time smooth the surface. Then, after cleaning the disc, the coating is completely cured. Then, after applying a lubricant to the magnetic layer, a surface smoothing treatment or the like is further performed to obtain a magnetic disk.

In this step, the resin substrate has a large coefficient of thermal expansion, and it is extremely difficult to eliminate the anisotropy of the coefficient of thermal expansion in the radial direction. For this reason, it has been considered that the resin substrate is not suitable for a high density medium having a small track pitch and a large areal recording density.

In Japanese Patent Laid-Open No. 61-24021, a groove is formed in a concentric pattern on the main surface of a disk substrate 51, and a magnetic layer is formed on the disk substrate.
A magnetic disk has been proposed in which the surface shape is an uneven shape having the same pattern as a groove, and recording / reproducing is performed in a land portion between the grooves.

In the case of a magnetic disk having such a groove 57, since the distance from the magnetic head in the groove increases and demagnetization due to separation loss increases, adjacent recording tracks can be separated by the groove. Therefore, crosstalk can be prevented even when the linear recording density is high.

However, in the case of the coating type magnetic layer, when the magnetic coating material is applied to the disk substrate, the grooves are filled with the magnetic coating material. Therefore, especially when the pitch or size of the grooves is small, the surface of the magnetic layer is formed into a groove pattern. It is extremely difficult to make the unevenness as it is.

In the case of a thin film magnetic disk, if a magnetic layer is formed on the disk substrate having an uneven pattern having grooves by, for example, sputtering, the magnetic layer 55.
However, the disk substrate 51 is deformed by heat during sputtering, contraction of the magnetic layer 55, or the like.

In this case, the groove may be deformed or broken when heated and pressed to straighten the magnetic disk.
Further, in the manufacturing process of a magnetic disk, generally, after the disk substrate is manufactured, the magnetic layer is formed on each disk substrate, so that the production efficiency is poor and it is very disadvantageous in mass production.

Further, in Japanese Patent Application Laid-Open No. 58-175138, a sheet having a magnetic layer on a thermoplastic resin substrate is inserted between metal plates which have been subjected to fine mirror surface processing, and the temperature above the softening point of the substrate is set. A method for manufacturing a magnetic disk is disclosed in which the metal plate is hot-pressed at a temperature, then cold-pressed to make the surface of the magnetic layer mirror-finished, and then the sheet is punched into a circular shape.

As specific examples, a magnetic disk using a 500 μm thick vinyl chloride film as a substrate and a magnetic disk using a 500 μm thick acrylic resin plate as a substrate are disclosed. According to the magnetic disk manufacturing method described in the above publication, production efficiency can be improved.

However, if a sheet having a magnetic layer formed on a substrate is hot-pressed and then punched into a circular shape, the substrate straightened by the hot-press may be slightly deformed, and a groove is formed on the sheet. In such a case, it is difficult to perform positioning when punching into a circle.

Further, the thickness of 500 μm shown in the above publication.
When a resin substrate having a diameter of m is used for a magnetic disk having an outer diameter of about 65 to 130 mm, the rigidity is insufficient, and a head crash may occur due to the bending of the magnetic disk when the magnetic disk starts rotating.

[0019]

SUMMARY OF THE INVENTION A main object of the present invention is to form a groove, for example, a continuous or discontinuous pattern such as a groove for tracking, on a magnetic disk with high accuracy, excellent flatness, and advantageous in mass production. Another object of the present invention is to provide a method for manufacturing a magnetic disk, and a high-density, lightweight, high-density magnetic disk using a resin substrate.

[0020]

These objects are achieved by the present invention described in (1) to (7) below.

(1) A magnetic layer is formed on a resin-made rigid substrate, a disc body is obtained from the substrate on which the magnetic layer is formed, and the disc body is heated, and / or
While heating the disc body, a pair of pressurizing means having a convex portion on the surface is used to apply pressure to almost the entire major surfaces of the disc body in the disc thickness direction at the same time. 1. A method for manufacturing a magnetic disk, comprising forming continuous or discontinuous grooves in a predetermined direction.

(2) A magnetic layer is formed on a rigid substrate made of resin, and at the same time as obtaining a disc body from the substrate on which the magnetic layer is formed, while heating the disc body,
Using a pair of pressurizing means having a convex portion on the surface, almost the entire main surfaces of the disc body are simultaneously pressed in the disc thickness direction to form continuous or discontinuous grooves in the disc circumferential direction on the disc body surface. A method of manufacturing a magnetic disk, which comprises forming the magnetic disk.

(3) The heating temperature during the heating is 40 to 3
The press pressure at the time of pressurization is 1 to 500 kg.
The method for producing a magnetic disk according to (1) or (2) above, wherein the magnetic disk has f / cm ² .

(4) The method of manufacturing a magnetic disk according to any one of (1) to (3) above, wherein the groove is formed in a continuous or discontinuous concentric circle shape or a spiral shape on the surface of the magnetic disk.

(5) The width of the groove is 20 μm or less, the depth of the groove is 3 μm or less, and the width of the land portion of the inter-groove is 10
The method for producing a magnetic disk according to any one of (1) to (4) above, which has a thickness of 0 μm or less.

(6) A coating type magnetic layer containing magnetic fine particles is provided on a rigid disk substrate made of resin, which is manufactured by the method described in any one of (1) to (5) above. Characteristic magnetic disk.

(7) The magnetic disk according to the above (6), wherein the magnetic fine particles are ferromagnetic metal fine particles or hexagonal oxide fine particles.

[0028]

In the magnetic disk manufacturing method of the present invention, first,
A magnetic paint is applied on a rigid base made of resin to form a magnetic coating film, or a continuous magnetic thin film is formed. Next, a plurality of disk bodies are obtained by punching or the like from the base body on which the magnetic layer is formed. Then, after heating the disk body and / or while heating the disk body, the disk body is made to have a disk thickness by using a pressing means having a convex pattern of a predetermined pattern, such as continuous or discontinuous concentric circles or spirals, on the surface. Press in the direction. Alternatively, in the step of obtaining a plurality of disc bodies from the substrate on which the magnetic layer is formed, almost simultaneously with obtaining one disc body, the disc bodies are heated while the surface is continuous or discontinuous, such as concentric circles and spirals. The disk body is pressed in the disk thickness direction by using the pressing means having the projections of the predetermined pattern.

By this pressurization and heat treatment, the disk body, that is, the disk substrate, the magnetic coating film and the continuous magnetic thin film are deformed, and a groove of a predetermined pattern, for example, a groove for high precision tracking, is formed on the surface of the magnetic disk. A continuous or discontinuous uneven pattern can be formed.

Since no information is recorded in the groove thus formed, the continuous or discontinuous groove functions as a guard band regardless of the position of the magnetic head. Therefore, if the magnetic disk is provided with the groove, it is not necessary to electrically write the servo signal, and the accuracy of the tracking servo can be improved. Also, crosstalk from adjacent tracks is significantly reduced. At this time, it is also possible to use tracking servo using laser light.

Further, according to the present invention, since a magnetic layer is formed on a substrate and then a plurality of disk bodies are obtained from this substrate, a magnetic layer is formed for each disk substrate as compared with the conventional manufacturing method. Very advantageous for mass production.

When the disk body is punched from the base body or the like, even if the disk body is undulated or distorted, the entire disk body is simultaneously pressed by using a pair of flat plate-shaped pressing means having an uneven pattern. Therefore, the disc body can be corrected while maintaining the shape of the groove.

In addition, particularly in the case of manufacturing a coating type magnetic disk, the pressure and heat treatment described above smoothes the surface of the coating film, apart from the irregularities due to the grooves, and provides a uniform surface roughness on the disk substrate. And a magnetic layer having a uniform thickness can be formed.

As a result, the surface wobbling and surface wobbling acceleration are reduced, and the modulation of the reproduction output can be reduced.
/ N is improved, and good recording and reproduction can be performed. Moreover, the pressure and / or heat treatment reduces the porosity of the magnetic layer and increases the residual magnetic flux density Br.

[0035]

[Specific Structure] The specific structure of the present invention will be described in detail below.

The magnetic disk of the present invention has a magnetic layer on a rigid disk substrate made of resin. In this case, even on a single-sided recording type magnetic disk having a magnetic layer on one of the main surfaces of the disk substrate, on both main surfaces of the disk substrate,
It may be a double-sided recording type magnetic disk each having a magnetic layer.

Further, the magnetic layer may be a coating type magnetic layer obtained by curing a coating film of magnetic paint containing magnetic fine particles or a magnetic layer of continuous magnetic thin film.

In the method of manufacturing a magnetic disk of the present invention, first, a rigid substrate made of resin is manufactured.

The shape of the substrate is not particularly limited and may be appropriately selected according to the purpose and application, but it is usually a thin plate. The size of the base is not particularly limited as long as two or more disk bodies can be obtained from the base, and may be appropriately selected according to the purpose and application.

For example, if the size of the main surface (magnetic layer forming surface) of the substrate is about 0.1 to 0.5 m × 0.1 to 10 m, and the thickness is about 0.8 to 1.9 mm. Good.

The rigidity of the substrate is quantitatively different depending on the outer diameter of the disc body obtained from the substrate and cannot be uniquely determined, but the outer diameter of the disc body is 65 to 130.
For about mm, a Young's modulus of the substrate E, when the thickness was set to t, E · t ^3/12 is 1 × 10 ⁶ dyn · cm or more, more preferably 1.5 × 10 ⁶ dyn · cm or more This is the case.

[0042] When the outer diameter of the disc body of about 65~130mm, E · t ^3/12 is less than the deflection magnetic disk, there is a tendency that the head crash occurs during rotation start. Incidentally, when the outside diameter of the disk body is less than about 65mm is no problem even if less than the value of E · t ^3/12 is the.

The resin used for the substrate is not particularly limited, and any resin such as a thermoplastic resin, a thermosetting resin and an active energy ray curable resin may be used.

For example, polyethylene, polypropylene,
Vinyl chloride resin, vinylidene chloride resin, vinylidene fluoride resin, polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylic resin, polyamide, polycarbonate,
Polyacetal, polyester, polysulfone, polyoxybenzylene, polyethersulfone, polyetherketone, polyetheretherketone, polyphenylene sulfide, polyphenylene ether, polyphenylene oxide, polyketone sulfide, polyimide,
Polyamide imide, polyacryl imide, polyether imide, polyolefin, amorphous polyolefin, polyester, polyurethane, epoxy resin, silicone resin and modified products thereof can be used.

Among these various non-magnetic materials, the mechanical strength is high and the workability and the like are good. Particularly, in view of easy formation of grooves by pressure and heat treatment described later, it is possible to use polycarbonate, polyolefin, poly It is preferable to use a thermoplastic resin such as ether imide.

The method for producing the substrate is not particularly limited, and for example, it may be formed into a plate shape by a known method such as extrusion roll processing.

On the surface of the obtained substrate, for the purpose of preventing electrification, increasing the hardness of the substrate, improving the adhesion between the substrate and the magnetic layer, etc., especially when a continuous thin film magnetic layer is formed, Various underlayers may be provided for the purpose of preventing cracks in the layer, improving corrosion resistance, and preventing degassing from the substrate.

The thickness of the underlayer is usually 100 to 3000A.
It should be about. The base layer to be formed may be appropriately selected depending on the purpose, the type of magnetic layer, and the like.

A magnetic layer is formed on the substrate directly or via an underlayer or the like provided as necessary.

The magnetic layer is classified into the coating type and the continuous thin film type as described above, and the cases will be described separately below.

[Magnetic Layer (1)] The first example of the magnetic layer is a coating type magnetic layer. The magnetic layer is formed by applying a magnetic coating material containing magnetic fine particles on a substrate.

The coercive force of the magnetic layer is preferably 700 Oe or more. If the coercive force is less than this value, sufficient electromagnetic conversion characteristics cannot be obtained, high density recording becomes difficult, and high reproduction output cannot be obtained.

The coercive force of the magnetic layer may be set in a range where sufficient overwrite characteristics can be obtained in consideration of the performance of the magnetic head to be combined. Therefore, there is no upper limit, but it is usually 3000 Oe or less. preferable.

The magnetic fine particles used in the coating type magnetic layer are not particularly limited, and various oxide magnetic powders can be used, but magnetic fine particles having a high coercive force, for example, ferromagnetic metal fine particles are preferable. High recording density and high recording / reproducing sensitivity can be obtained by using magnetic fine particles having high coercive force such as ferromagnetic metal fine particles.

In this case, the ferromagnetic metal fine particles to be used are not particularly limited, but it is preferable to select them so as to obtain the above magnetic characteristics.

For example, simple substances of Fe, Co and Ni, alloys of these, or simple substances and alloys of these, Cr, M
n, Co, Ni, and further Zn, Cu, Zr, Al, T
Ferromagnetic metal particles to which i, Bi, Ag, Pt, etc. are added can be used.

Further, B, C, Si, P, and
It may be added with a small amount of a non-metal element such as N, or may be partially nitrided such as Fe ₄ N.

Further, the ferromagnetic metal fine particles may have an oxide film on the surface in order to improve corrosion resistance and weather resistance. As such oxides, oxides of metals forming ferromagnetic metal fine particles and various ceramics such as Al ₂ O ₃ are preferable.

The shape of the ferromagnetic metal fine particles is not particularly limited, but it is preferable to use the acicular shape because the shape magnetic anisotropy can be utilized.

The size of the magnetic fine particles may be selected according to the intended structure of the magnetic layer, but the major axis is usually 0.1.
It is preferable to use one having a needle-shaped ratio of about 5 to 0.30 μm and a needle-shaped ratio of about 6 to 10.

When using ferromagnetic metal fine particles,
It may be produced by various known methods such as a method of reducing α-FeOOH (Goethite), or a commercially available one may be used.

Magnetic fine particles utilizing crystal anisotropy include hexagonal oxide fine particles such as barium ferrite and strontium ferrite.

In this case, the size of the hexagonal oxide fine particles may be selected according to the intended constitution of the magnetic layer, but the average particle size is 0.15 μm or less, especially 0.02 due to electromagnetic conversion characteristics. .About.0.10 .mu.m, and the plate ratio is 2 or more, particularly preferably 3 to 10.

Here, the average particle size means, for example, about 50 hexagonal barium ferrite particles are observed by an electron microscope photograph [scanning electron microscope (SEM) and transmission electron microscope (TEM)], It is the average of the measured values for the diameter. The plate ratio is a value of average particle diameter / average thickness.

As barium ferrite, BaFe ₁₂
Hexagonal barium ferrite such as O ₁₉ and Ba and Fe of barium ferrite are partially Ca, Sr, Pb, Co and N.
i, Ti, Cr, Zn, In, Mn, Cu, Ge, N
Examples thereof include those substituted with one or more selected from b, Zr, Sn and other metals.

As the strontium ferrite, hexagonal strontium ferrite SrFe is used.
_It may be ₁₂ O ₁₉ or one obtained by substituting it according to the above.

In this case, in order to increase the amount of magnetization and improve the temperature characteristics, a hexagonal ferrite surface modified with spinel ferrite may be used. Further, in order to improve weather resistance and dispersibility, the surface of these particles may have a coating film of oxide or organic compound.

Examples of the method for producing barium ferrite and the like include a ceramic method, a coprecipitation-firing method, a hydrothermal synthesis method, a flux method, a glass crystallization method, an alkoxide method, a plasma jet method and the like, and any method is used in the present invention. You may use. For details of these methods, reference can be made to Yoshiyasu Koike and Osamu Kubo, "Ceramics 18 (1983) No. 10".

The magnetic coating material used for forming the magnetic layer is usually prepared by kneading the above-mentioned magnetic fine particles, a binder and a solvent. In this case, the magnetic fine particles may be used in combination of two or more, if necessary.

The binder to be used is not particularly limited and may be selected from thermosetting resins, reactive resins, active energy ray curable resins such as ultraviolet curable and radiation curable resins according to the purpose. A thin layer ensures sufficient film strength,
Since it is necessary to obtain high durability, it is preferable to use a thermosetting resin or an active energy ray curable resin such as an ultraviolet curable resin and a radiation curable resin.

Examples of the thermosetting resin include phenol resin, epoxy resin, vinyl copolymer resin, polyurethane curable resin, urea resin, butyral resin, formal resin, melamine resin, alkyd resin, silicone resin and acrylic reaction. Resin, polyamide resin, epoxy-
Polyamide resin, saturated polyester resin, polycondensation resin such as urea formaldehyde resin or a mixture of high molecular weight polyester resin and isocyanate prepolymer, a mixture of methacrylate copolymer and diisocyanate prepolymer, a mixture of polyester polyol and polyisocyanate, Mixtures of the above polycondensation resin and a crosslinking agent such as an isocyanate compound, such as a mixture of low molecular weight glycol / high molecular weight diol / triphenylmethane triisocyanate, a mixture of a vinyl copolymerization resin and a crosslinking agent, nitrocellulose, cellulose A mixture of a fibrin-based resin such as acetobutyrate and a crosslinking agent, butadiene-
A mixture of a synthetic rubber system such as acrylonitrile and a crosslinking agent,
Furthermore, mixtures of these are preferred.

Particularly, a mixture of an epoxy resin and a phenol resin, a mixture of an epoxy resin described in US Pat. No. 3,058,844, a polyvinyl methyl ether and a methylol phenol ether, and JP-A-49-13.
A mixture of the bisphenol A type epoxy resin described in No. 1101 and an acrylic acid ester or a methacrylic acid ester polymer is preferable.

Specific examples of the active energy ray-curable compound include acrylic double bonds having a radical-polymerizable unsaturated double bond, acrylic double bonds such as acrylic acid and methacrylic acid, or ester compounds thereof, and diallyl phthalate. Resins containing or introducing into the molecule of a thermoplastic resin such groups as allylic double bonds, unsaturated bonds such as maleic acid, maleic acid derivatives and the like which are crosslinked or polymerized by irradiation with radiation. In addition, any compound having an unsaturated double bond that undergoes cross-linking polymerization upon irradiation with radiation can be used.

As the resin used as the radiation curable binder, a saturated or unsaturated polyester resin containing the above unsaturated double bond in the molecular chain, terminal or side chain of the resin, polyurethane resin, vinyl chloride resin, polyvinyl resin. Alcohol-based resins, polyvinyl butyral-based resins, epoxy resins, phenoxy resins, fibrin-based resins, acrylonitrile-butadiene copolymers, polybutadiene and the like are suitable.

Further, the radiation curable compounds used in the present invention as oligomers and monomers include monofunctional or polyfunctional triazine acrylates, polyhydric alcohol acrylates, pentaerythritol acrylates, ester acrylates, urethane acrylates and A monofunctional or polyfunctional methacrylate compound of the above system is suitable.

The content of the binder in the magnetic coating material is not particularly limited, but it is 10-50 per 100 parts by weight of the magnetic fine particles.
It is preferable that the amount is about parts by weight.

The solvent to be used is not particularly limited, and various solvents such as a ketone system such as cyclohexanone and isophorone, an alcohol system such as isopropyl alcohol and butyl alcohol, a cellosolve system such as ethyl cellosolve and a cellosolve acetate, and an aromatic system such as toluene. It may be selected according to the purpose.

The content of the solvent in the magnetic coating material is not particularly limited, but is 200 to 700 with respect to 100 parts by weight of the magnetic fine particles.
It is preferable that the amount is about parts by weight.

In order to enhance the mechanical strength of the magnetic layer, α-Al ₂ O ₃ , Cr ₂ O ₃ , TiO ₂ ,
It is preferable to contain inorganic fine particles such as SiC and α-Fe ₂ O ₃ . If necessary, a lubricant such as silicone oil and other various additives may be added to the magnetic paint.

Such a magnetic paint is applied to the surface of a resin base to form a coating film of the magnetic paint.

In this case, the surface of the substrate or the surface of the underlayer, which is provided if necessary, may be treated with a coupling agent, a curable resin or the like.

There is no particular limitation on the method of applying the magnetic paint,
For example, a die coating method, a dip coating method, a spray coating method, a roll coating method or the like may be used.

After applying the magnetic paint, the magnetic fine particles in the coating film are oriented as necessary. In this case, it is preferable that the easy axis of magnetization of the coating film is oriented in a random direction within the main surface of the substrate or in the thickness direction of the substrate, that is, the disc thickness direction. The orientation may be performed according to a conventionally known method.

Before orientation, a magnetic field may be applied in solvent vapor to level the coating film.

Then, a rigid disk body is obtained from the substrate on which the magnetic coating film is formed. The method of obtaining the disk body is not particularly limited, and a known method such as a method of cutting into a disk shape using a laser or a method of punching into a disk shape using a punching device may be used.

An example of the punching device is shown in FIG. 1 and will be described below with reference to the illustrated example. The punching device has a cylindrical convex portion 75 at the center, an upper blade 7 having a ring-shaped convex portion 73 having a rectangular cross section on the outer peripheral portion, and a ring-shaped lower blade 8 having a concave portion 81.

The convex portion 73 regulates the outer diameter of the disc body,
The convex portion 75 is for regulating the inner diameter of the disk body, and the upper blade 7 is formed with a ring-shaped concave portion 71 having a rectangular cross section by the convex portions 73 and 75.

The lower blade 8 is fixed to the mounting base 3, and the lower punching plate 93 is mounted inside the recess 81 via the spring 6.

The upper blade 7 is arranged so that the concave portion 71 and the lower blade 8 face each other, and inside the concave portion 71 of the upper blade 7,
The upper punching plate 91 is attached via the spring 6.

Further, on the mounting base 3 on the outer peripheral side of the lower blade 8, a ring-shaped upper blade punching plate 95 is provided via a spring 6 at a position facing the ring-shaped convex portion 73 of the upper blade 7. Is attached.

On the lower blade 8 of such a punching device, the substrate 41 having the coating films 53, 53 formed on both main surfaces is placed.

Next, the upper blade 7 and the lower blade 8 are actuated to punch the coating film and the substrate into a disk shape to obtain a disk body having the coating film on the disk substrate. Then, in the same manner, a plurality of disc bodies are punched out from the substrate on which one coating film is formed.

As described above, according to the present invention, a plurality of discs having a coating film can be obtained by one-time application, so that mass productivity is remarkably higher than that of the conventional method of forming a coating film on each disc substrate. improves.

The size of the disk body may be appropriately selected depending on the purpose and application, but is usually about 65 to 130 mm in outer diameter, 20 to 40 mm in inner diameter, and 0.8 to 1.9 mm in thickness. ..

The conditions for punching may be appropriately determined depending on the outer diameter, thickness, etc. of the disk body, but normally, the hydraulic cylinder discharge pressure: about 50 to 150 kgf / cm ² , the upper blade descending speed: 3 to Punching is performed at about 20 mm / sec.

After the disc body is punched out from the substrate on which the coating film has been formed, substantially the entire principal surfaces of the disc body are simultaneously pressed in the disc thickness direction to form grooves in the disc circumferential direction on the surface of the disc body. To do. In this case, before pressurizing the disc body, the disc body is heated to a predetermined temperature. In addition to or in addition to this, heating is performed during hot pressing, for example, by hot pressing.

It should be noted that if pressure is not applied to both main surfaces of the disk body at the same time using, for example, a conical roller, the disk body will be distorted. For this reason, it becomes difficult for the magnetic head to follow during tracking, and a head crash may occur especially when the distortion or waviness is severe. Moreover, recording / reproducing becomes difficult.

The apparatus used in the present invention is not particularly limited as long as it can press both main surfaces of the disc body in the disc thickness direction at the same time and can form a groove on the surface of the disc body. However, when heating is performed during pressurization, it is necessary to provide a hot press mechanism. One example is shown in FIG. 2 and will be described below.

The device has a pair of pressurizing means 1, 2.
The pair of pressurizing means 1 and 2 are respectively press plates 11 and 2.
1 and stampers 13 and 23.

As shown in the drawing, the surfaces of the pair of stampers 13 and 23 that determine the surface properties of the disk body 50 are processed into desired concavo-convex shapes, for example, continuous or discontinuous concentric circles and spirals. And the like are regularly formed with convex portions and concave portions. And, the surface of the convex portion and the concave portion,
It is processed to have a desired surface roughness (Ra).

In order to heat and pressurize the disc body 50, first, the disc body 50 having the coating film 53 on the disc substrate 51 is heated by using a conventionally known heating means such as heating in a far infrared furnace. To do. After that, the heated disk body 50 is placed on the stamper 23 that is arranged to face the press plate 21. Next, the stamper 13 is placed on the disc body 50, and the press plate 11 and the press plate 21 are placed.
In the meantime, the disc body 50 is pressed in the disc thickness direction.

The disk body 50 may not be heated before the pressurization, or the disk body 50 may be heated while being pressurized in addition to the above heating.

Various conditions such as the press pressure, heating temperature, pressurization / heating time, etc. may be appropriately determined according to the material of the binder, the material of the disk substrate 51 and the like. In this case, the heating temperature is usually equal to or higher than the thermal deformation temperature of the disk substrate 51, and
0-300 degreeC, especially 60-250 degreeC are preferable. Also,
The pressing pressure is 1 to 500 kgf / cm ² , more preferably,
1 to 300 kgf / cm ² , more preferably 5 to 150 kgf /
cm ² , particularly preferably 10 to 100 kgf / cm ² . The pressurizing time is preferably 30 minutes or less, particularly 15 minutes or less.

In this way, the disk substrate 51 and the coating film 53 are deformed, and the patterns on the surfaces of the stampers 13 and 23 are directly transferred to the surface of the disk body 50 to form grooves having a desired pattern. To correct the shape of. At this time, whether only the magnetic layer is deformed or both the magnetic layer and the substrate are deformed depends on various conditions such as heating temperature, pressing pressure, magnetic layer, substrate material, and thickness.

In the method for manufacturing a magnetic disk of the present invention, the positioning is not necessary and the mass productivity is improved, so that the disk body 50 is punched from the base body 41 having the coating film 53 and the disk body 50 is added. It is preferable to carry out the pressure and heating treatments almost simultaneously.

In order to carry out simultaneously, it is sufficient to use the apparatus having both the punching mechanism and the pressurizing and heating mechanism, and perform the treatment under the above conditions.

Then, if necessary, various curing treatments are performed to cure the coating film 53 on the disk substrate 51 to form a magnetic layer. When a thermosetting binder is used, the curing conditions are preferably a temperature of about 60 to 250 ° C. and a heating time of about 1 to 48 hours.

Further, the curing condition when using the radiation-curable binder is preferably a radiation dose of about 2 to 10 Mrad. When a thermosetting binder is used, the curing treatment may be performed at the same time as the pressure and heat treatments.

If necessary, so-called chamfering or the like may be performed to form a radius R on the end faces of the inner peripheral portion and the outer peripheral portion of the disk body.

After the coating film 53 is cured, polishing processing such as tape polishing is performed if necessary. Then, after that, it is preferable to apply a liquid lubricant to the surface of the magnetic layer to impregnate the magnetic layer. There is no limitation on the method of applying the liquid lubricant, and for example, a dipping method, a spin coating method or the like may be used.

After impregnation with the liquid lubricant, it is preferable to further improve the smoothness of the magnetic disk surface by performing burnishing again.

In this way, the double-sided recording type magnetic disk 5 having the grooves 57 on both main surfaces as shown in FIG. 3 is manufactured. In the case of a single-sided recording type magnetic disk,
The groove 57 may be formed on the side where the magnetic layer 55 is formed.

The grooves 57 are regularly formed in the disk circumferential direction and are mainly used as tracking grooves or pits.

The pattern of the groove 57 is not particularly limited, and is usually a concentric or spiral continuous groove or a discontinuous or continuous dot-like pit. Further, the cross-sectional shape of the groove 57 is not particularly limited and may be various shapes such as a V-shape and a rectangle. Further, the dimensions of the grooves 57, the intervals between the grooves 57, the discontinuous dimensions of the discontinuous grooves, etc. are not particularly limited and may be appropriately determined according to the purpose, etc., but the following dimensions are preferable.

Width a of groove 57: 20 μm or less, especially 10 μm
m or less and generally 0.2 μm or more, especially 0.5 μm
Depth h of groove 57: 3 μm or less, particularly 1 μm or less, generally 0.03 μm or more, particularly 0.05 μm or more Width b of land portion 59 between grooves: 100 μm or less, particularly 50 μm or less, generally 0.2 μm or more, Especially 0.5 μm
that's all

The widths b of the lands 59 are normally equidistant, but may be gradually increased on the inner peripheral side.

The residual magnetic flux density Br of the coating type magnetic disk 5 manufactured in this manner is about 1000 to 3000 G,
Squareness ratio S is about 0.70 to 0.95, coercive force squareness ratio S ^*
Is about 0.70 to 0.95.

[Magnetic Layer (2)] The second example of the magnetic layer is a continuous magnetic thin film. The material of the continuous magnetic thin film is not particularly limited, and may be, for example, a continuous thin film containing at least one selected from Fe, Co and Ni, particularly a Co-based continuous thin film.

A specific example of the composition of the magnetic layer is Co--N.
i alloy, Co-Ni-Cr alloy, Co-Cr alloy, Co
-Cr-B alloy, Co-Cr-Mn alloy, Co-Cr-
Mn-B alloy, Co-Cr-Ta alloy, Co-Cr-S
i-Al alloy, Co-V alloy, Co-Ni-P alloy, C
O-P alloy, Co-Zn-P alloy, Co-Ni-Pt alloy, Co-Pt alloy, Co-Ni-Mn-Re-P alloy, etc. are mentioned.

If necessary, these alloys may contain O,
Other elements such as N, Si, Al, Mn, and Ar may be contained in an amount of about 0.1% by weight or less.

The thickness of the magnetic layer is preferably 300 to 1000A.

If it is less than the above range, the output during recording and reproduction is insufficient, and if it exceeds the range, the recording density is lowered.

A non-magnetic intermediate layer is provided, if necessary, between the substrate and the magnetic layer or between the magnetic layer and the underlayer which is formed as necessary.

For example, the magnetic layer may be Co-Ni or Co-Ni.
-Cr, Co-Cr, Co-Cr-Ta, Co-Ni-
In the case of being composed of P, Co-Zn-P, Co-Ni-Mn-Re-P, etc., by providing the non-magnetic intermediate layer, the epitaxial growth of the magnetic layer can be favorably performed.
Magnetic properties are improved.

The non-magnetic intermediate layer is, for example, one or more selected from Cr, Mo and W, especially Cr and / or W.
It may be constituted by a continuous magnetic thin film containing.

In this case, the metal used may be a simple substance or an alloy, but in the case of an alloy, it is preferable to contain the metal in an amount of 80% by weight or more.

The thickness of the nonmagnetic intermediate layer is 500 to 5000.
A is preferred.

If the amount is less than the above range, the epitaxial growth of the magnetic layer is insufficient, and good magnetic characteristics cannot be obtained. When the value exceeds the above range, the magnetic characteristics of the magnetic layer converge to a substantially constant value, which is meaningless in terms of magnetic characteristics and is disadvantageous in mass production.

The non-magnetic intermediate layer and the magnetic layer are
Each film may be formed by various vapor phase film forming methods such as vapor deposition, sputtering, ion plating, and CVD, and it is particularly preferable to form the film by sputtering.

When the magnetic layer of the continuous magnetic thin film is formed on the substrate, the disk body is obtained, and the pressing and heating are performed in the same manner as the case of forming the coating type magnetic layer described above after the continuous magnetic thin film is formed. Then, a desired continuous or discontinuous groove is formed on the surface of the disk body. Also in this case, various conditions such as the shape of the groove, the pattern, the dimension, and the groove arrangement interval may be various as described above.

If necessary, a protective layer, an organic liquid lubricating film, or the like may be further provided on the continuous thin film type magnetic layer.

The protective layer is usually composed of carbon or carbon to which other elements are added in an amount of about 5% by weight or less, and the film thickness thereof may be set to about 300 to 1000 A.

The lubricating film is usually composed of a fluorinated liquid lubricant or the like, and the film thickness may be about 5 to 20A.

The protective layer and the like may be formed by various vapor phase film forming methods, particularly sputtering. Further, the lubricating film or the like may be formed by dip coating, spray coating, or spin coating.

The work of punching the disk body from the substrate may be performed immediately after the magnetic layer is formed, as described above.
In some cases, it may be performed after forming a protective layer, an organic liquid lubricating film, or the like on the magnetic layer.

Next, a magnetic recording / reproducing method using the magnetic disk of the present invention will be described.

The magnetic head used in combination with the magnetic disk of the present invention is a metal-in-gap (MIG).
Type magnetic heads, thin film type magnetic heads, composite types of these and MR heads, and magnetic heads equipped with a semiconductor laser for the purpose of optical servo are preferable.

The MIG type magnetic head is a magnetic head having a soft magnetic thin film having a saturation magnetic flux density higher than those of the cores on at least one of the pair of cores facing the gap portion. In the MIG type magnetic head, since a strong magnetic flux can be applied to the magnetic layer from the soft magnetic thin film, effective recording can be performed on the magnetic layer having a high coercive force. Further, in the present invention, a so-called enhanced dual gap length (EDG) type magnetic head which is a kind of MIG type magnetic head may be used.

The number of revolutions of the magnetic disk at the time of recording / reproducing is not particularly limited, and may be appropriately set according to the target system environment such as transfer rate, flying height, recording density, etc., but is, for example, about 1500 to 4000 rpm. .. In this case, since a lightweight resin disk substrate is used in the present invention, high-speed rotation drive at about 4000 rpm is possible, and a high transfer rate can be obtained.

In the present invention, since a digital signal is usually recorded, saturation recording is performed. Further, since saturated recording is performed, overwrite recording is possible.

[0141]

EXAMPLES The present invention will be described in more detail with reference to specific examples of the present invention.

Example 1 The dimension of the main surface was 0.3 m × by extrusion roll processing.
A thin plate-shaped substrate made of polyetherimide (Ultem) having a thickness of 0.3 m and a thickness of 1.27 mm was manufactured. Substrate E · t ³
/ 12 (E is Young's modulus, t is thickness) is 5.1 × 10 ⁶ dyn
-Cm 2, heat distortion temperature was 20 ℃.

Next, the magnetic paint was prepared as follows. Magnetic powder 100 parts by weight Barium ferrite Coercive force: 940 Oe Average particle size: 0.05 μm Plate ratio: 3 Alumina 3 parts by weight Epoxy resin (Epicoat 1004, Shell Chemical Co., Ltd.) 20 parts by weight Heat distortion temperature: 98 ° C. Phenolic resin (Sumirac PC25, manufactured by Sumitomo Bakelite Co., Ltd.) 20 parts by weight Heat distortion temperature: 170 ° C. Cyclohexanone / isophorone (1/1 mixed solvent) 450 parts by weight The above composition was mixed and dispersed in a ball mill for 80 hours.

The magnetic coating material thus obtained was applied onto a substrate by a die coating method to form a magnetic coating film.

Then, the coating film was dried after carrying out an alignment treatment in the thickness direction of the substrate with an aligning device having magnets having mutually different poles opposed to each other.

Then, a disc body is formed from a substrate on which a coating film is formed by using an apparatus having a punching mechanism shown in FIG. 1 and a pressure / heating mechanism shown in FIG. 2 and a stamper for forming a groove for tracking. Simultaneously with punching, the disk body was heated while simultaneously applying pressure to both main surfaces of the disk body to form concentric circular grooves for tracking on both main surfaces of the disk body, and at the same time, the coating film was cured.

The obtained disk body had an outer diameter of 3.5 inches and a thickness of about 1.27 mm, and the groove had a substantially rectangular cross section. The groove had a width of 10 μm and a depth of 1 μm.
m, and the land portion width was 20 μm.

The processing conditions were as follows. Pressurization and heating conditions Press pressure: 100 kgf / cm ² Heating temperature: 220 ° C Pressing time: 15 minutes

Punching conditions Hydraulic cylinder discharge pressure: 90 kgf / cm ² Upper blade lowering speed: 5 mm / sec

Then, after cooling with cooling water and taking out the disk body at a temperature of 100 ° C. or less, WA # 800
Burnishing was performed by a tape polishing device using 0 polishing tape. After that, the disk body is washed, and a fluorocarbon (KRYTOX 14
A CFC solution (3CZ: manufactured by DuPont) was applied by a dip method and impregnated to prepare a double-sided recording type magnetic disk sample No. 1. The thickness of the magnetic layer was 0.40 μm.

Sample No. 1 was prepared by using a disk substrate having grooves formed by injection molding for comparison, except that the coating film was heat-cured at 220 ° C. for 30 minutes without punching, pressurizing and heating. A sample similar to that of No. 1 was prepared, and this was designated as Comparative sample No. 2.

Example 2 Sample No. 3 was prepared using the same substrate as the sample No. 1 of Example 1 and the following magnetic coating material using a radiation curable binder. The coating composition is as follows. Magnetic powder 100 parts by weight Barium ferrite Coercive force: 940 Oe Average particle size: 0.05 μm Plate ratio: 3 Alumina 3 parts by weight Acrylic double bond-introduced vinyl chloride-vinyl acetate copolymer (containing 1% maleic acid: weight average) Molecular weight 50,000 28 parts by weight (solid content) Acrylic double bond-introduced polyether urethane elastomer (weight average molecular weight 50,000) 12 parts by weight (solid content) Pentaerythritol triacrylate 4 parts by weight Stearic acid 4 parts by weight Parts Butyl stearate 10 parts by weight Cyclohexanone / isophorone (1/1 mixed solvent) 450 parts by weight The above composition was mixed and dispersed in a ball mill for 80 hours.

The magnetic coating material thus obtained was applied onto a substrate by a die coating method to form a magnetic coating film.

Next, after an orientation treatment was performed in the thickness direction of the substrate by an orientation device in which magnets having different poles opposed to each other were arranged, the coating film was dried.

Then, the punching device shown in FIG. 1 was used to punch the disc body from the substrate on which the coating film was formed. The conditions for punching were as follows. Hydraulic cylinder discharge pressure: 90kgf / cm ² Upper blade lowering speed: 5mm / sec

The obtained disk body had an outer diameter of 3.5 inches and a thickness of about 1.27 mm.

After that, the disk body was preheated to a surface temperature of 220 ° C. by using a far infrared device, and immediately the entire both main surfaces of the disk body were simultaneously heated by using the pressurizing device shown in FIG. By pressing, concentric grooves for tracking were formed on both main surfaces of the disk body, and after cooling, the disk body was taken out.

The groove has a substantially rectangular cross section, and the groove has a width of 10 μm, a depth of 1 μm, and a land width of 20 μm.
m.

The processing conditions were as follows. Surface temperature of disk during preheating: 220 ℃ Pressing pressure: 100kgf / cm ² Pressing time: 1 minute

Then, using an electron curtain type electron beam accelerator, an accelerating voltage of 150 KeV and an electrode current of 20 were used.
The coating film was cured by irradiating it with an electron beam under a nitrogen atmosphere under the conditions of mA and a total irradiation amount of 5 Mrad.

Then, after washing the disc body, WA
After burnishing using a # 8000 polishing tape with a tape polishing apparatus, a fluorocarbon (KRYTOX 143CZ: manufactured by DuPont) fluorocarbon solution having a concentration of 0.1% was applied to the magnetic layer by a dip method to impregnate it. A double-sided recording type magnetic disk sample No. 3 was prepared. The thickness of the magnetic layer was 0.40 μm.

For comparison, a disk substrate having grooves formed by injection molding was used, and a sample similar to sample No. 3 was prepared except that punching, preheating and pressure treatment were not carried out. It was No. 4.

Example 3 A film having a thickness of 100 was formed on the same substrate as the sample No. 1 of Example 1.
A 0 A Al underlayer was deposited.

Co-Pt-Cr with a film thickness of 500 A
After forming the magnetic layer, a C protective layer having a film thickness of 400 A was formed.

In this case, the underlayer, the magnetic layer and the protective layer were formed by the DC-magnetron patterner. Also, the sputtering conditions are that the operating pressure is 1 Pa and Ar is
In the atmosphere.

Then, using the same punching device as in Example 2, a disk body having the same size as that of Sample No. 1 was punched. The conditions for punching were as follows.

Hydraulic cylinder discharge pressure: 90 kgf / cm ² Upper blade lowering speed: 5 mm / sec

Then, using the same apparatus for preheating and pressurizing as in Example 2, the same process operation as in Sample No. 1 was carried out except that the depth of the groove was 0.5 μm to form a groove. , Double-sided recording type magnetic disk sample
No. 5 was produced. The preheating and pressure treatment conditions were as follows.

Surface temperature of disk body during preheating: 220
℃ Pressing pressure: 100Kgf / cm ² Pressing time: 1 minute

For comparison, a disk substrate having grooves formed by injection molding was used, and a sample similar to sample No. 5 was prepared except that punching, preheating and pressure treatment were not carried out. It was No. 6.

The following items were evaluated for each of the above samples. (1) Surface blur The amount of axial surface blur (TI
R) and surface shake acceleration (ACC) were measured with an RVA tester. Measurement conditions are 3600 (± 36) rpm, 5KHz
(ACC), 1 kHz (TIR).

(2) Groove shape Cross-section observation / surface observation of each disk sample is performed by a transmission electron microscope (TEM) / scanning electron microscope (SE).
M) was used to evaluate the unevenness of the sample substrate and magnetic layer. The magnification is 5000 to 2000
It was set to 0 times.

Evaluation Criteria A: The magnetic layer is uniformly formed according to the unevenness of the groove on the substrate. O: The magnetic layer is formed uniformly according to the groove and groove on the substrate, but some cracks are observed in the magnetic layer. X: The unevenness of the groove on the substrate does not match the unevenness of the surface of the magnetic layer, and the unevenness on the substrate is not completely reproduced on the disk surface.

(3) Surface Roughness (Ra) The surface roughness (Ra) of each disk sample was measured according to JIS B 0 using a stylus profilometer (tally step).
It was determined according to 601.

Recording / reproduction was performed on each sample using a magnetic disk device having a flying magnetic head mounted thereon. Gap length 0.6μ for magnetic head
m monolithic type MIG head
The flying height of the head during reproduction was 0.25 μm.

(4) Modulation (MOD) A signal of a single wavelength of 3.3 MHz is recorded on the innermost circumference of the disc, and the output waveform envelope for one round is used to output P
The maximum value of the -P (peak to peak) value was A and the minimum value was B, and the modulation (MOD) was calculated from the following formula. MOD = (A−B) / (A + B) × 100 (%)

(5) S / N ratio The S / N ratio was measured at the innermost circumference of the disc as follows. After writing at a recording frequency of 3.3 MHz, the reproduction output (Vrms) was measured with an AC voltmeter in the band of 10 MHz.
Next, after performing DC erasing three times on this track, the reproduction output (V _DC rms) was measured with an AC voltmeter. The head was on-loaded and the system noise (Vnoise) was measured. Then, the S / N ratio was calculated from the following formula. S / N ratio = Vrms / (V _DC rms ² −Vnoise ² ) ^1/2 These results are as shown in Table 1.

[0178]

[Table 1]

From the results shown in Table 1, the effect of the present invention is clear.

The samples No. 1 and No. 1 of the present invention were used.
Sample No. 3 had a lower porosity of the magnetic layer and higher residual magnetic flux density than those of Comparative Samples No. 2 and No. 4.

Further, a coating type magnetic disk sample was prepared by using α-Fe fine particles, and the same evaluation was carried out, and the same result was obtained. Furthermore, the shape of the groove, the pattern and the dimension, the punching condition, or the Various coating-type magnetic disk samples obtained by changing the conditions such as the press pressure at the time of pressurization, the heating temperature and the pressurizing time, the composition of the magnetic fine particles, the binder, and the magnetic layer, or by obtaining the disk body by laser cutting. When a thin film magnetic disk sample was manufactured and evaluated in the same manner, the same result was obtained.

Example 4 In Example 1, the continuous groove pattern was a discontinuous pit pattern. The groove width of the pit is 0.8 μm,
The land width was 0.8 μm, the cross section was almost rectangular, the depth was 1600 A, and the pit length and spacing were each 40 MHz.
Separately from this, the pits were set to about 1.5 × 3.0 μm, the depth was 1600 A, and the gap was 40 MHz. As a result, the same results as in Example 1 were obtained.

[0183]

According to the method of manufacturing a magnetic disk of the present invention,
After forming the magnetic layer on the substrate, a plurality of disk bodies are obtained from this substrate, which is very advantageous in mass production.

Further, according to the method of manufacturing the coating type magnetic disk of the present invention, a magnetic layer having a uniform surface roughness and a uniform film thickness and a small porosity can be formed on the disk substrate, Moreover, it is possible to form continuous or discontinuous grooves for highly accurate tracking on the disk surface.

Unlike the case where pressure is applied by using a roller or the like, since the whole disk body is pressed at the same time, the magnetic disk is not distorted or undulated, and the disk body is not undulated by punching or the like. If it occurs, it can be corrected. Furthermore, the disc substrate has sufficient rigidity.

Therefore, there is no tracking error or head crash, and the modulation of the reproduction output is reduced, the S / N ratio is improved, and good recording / reproducing can be performed.

Further, since the concavo-convex pattern such as a groove for highly accurate tracking can be easily formed, the S / N ratio is improved.

Further, in the method for manufacturing a continuous thin film type magnetic disk of the present invention, a predetermined pressing means and heating means are used,
The deformation of the disk body due to heat at the time of sputtering, the contraction of the magnetic layer, etc. is corrected and the concavo-convex pattern is formed almost at the same time.

Therefore, a magnetic disk having an uneven pattern of a good shape and having high mechanical accuracy and dimensional accuracy without distortion or distortion is realized, the modulation of reproduction output is reduced, and the S / N is improved. Therefore, good recording / reproducing can be performed.

Since the magnetic disk of the present invention has a rigid disk substrate made of resin, it can be driven at high speed.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining a method for manufacturing a magnetic disk of the present invention.

FIG. 2 is a cross-sectional view for explaining the method of manufacturing a magnetic disk of the present invention.

FIG. 3 is a sectional view showing an example of a coating type magnetic disk of the present invention.

[Explanation of Codes] 1, 2 Pressurizing means 11, 21 Press plate 13, 23 Stamper 3 Mounting base 41 Base 5 Magnetic disk 50 Disk body 51 Disk substrate 53 Coating film 55 Magnetic layer 57 Groove 59 Land portion 6 Spring 7 Upper blade 71, 81 concave portion 73, 75 convex portion 8 lower blade 91 upper punching plate 93 lower punching plate 95 upper blade punching plate

Claims (7)

[Claims] 1. A magnetic layer is formed on a rigid base made of resin, and a disc body is obtained from the base body on which the magnetic layer is formed. The disc body is heated and / or the disc body is formed. While heating, a pair of pressurizing means having a convex portion on the surface is used to press almost the entire main surfaces of the disc body in the disc thickness direction at the same time to continuously or continuously press the disc body surface in the disc circumferential direction. A method for manufacturing a magnetic disk, which comprises forming discontinuous grooves. 2. A magnetic layer is formed on a rigid base made of resin, and at the same time as a disk body is obtained from the base body on which the magnetic layer is formed, a convex portion is formed on the surface while heating the disk body. Using a pair of pressurizing means, the two main surfaces of the disc body are simultaneously pressed in the disc thickness direction to form continuous or discontinuous grooves in the disc circumferential direction on the surface of the disc body. And a method for manufacturing a magnetic disk. 3. The heating temperature during the heating is 40 to 300 ° C.
And the pressing pressure at the time of pressurization is 1 to 500 kgf / cm ²
The method of manufacturing a magnetic disk according to claim 1, wherein 4. The method of manufacturing a magnetic disk according to claim 1, wherein the groove is formed in a continuous or discontinuous concentric circle shape or a spiral shape on the surface of the magnetic disk. 5. The width of the groove is 20 μm or less, the depth of the groove is 3 μm or less, and the width of the land portion of the inter-groove gap is 100 μm.
The method for manufacturing a magnetic disk according to claim 1, wherein: 6. A magnetic field produced by the method according to any one of claims 1 to 5, comprising a coating type magnetic layer containing magnetic fine particles on a rigid disc substrate made of resin. disk. 7. The magnetic disk according to claim 6, wherein the magnetic fine particles are ferromagnetic metal fine particles or hexagonal oxide fine particles.