WO2007119306A1

WO2007119306A1 - Substrate for magnetic recording medium, method for manufacturing such substrate and magnetic recording medium

Info

Publication number: WO2007119306A1
Application number: PCT/JP2007/054168
Authority: WO
Inventors: Hideki Kawai; Satoshi Nakano; Hajime Kobayashi; Yoshiharu Masaki; Shigeru Hosoe
Original assignee: Konica Minolta Opto, Inc.
Priority date: 2006-03-13
Filing date: 2007-03-05
Publication date: 2007-10-25
Also published as: JPWO2007119306A1

Abstract

Provided is a substrate for a magnetic recording medium, which has high chemical durability and improved adhesiveness with a magnetic layer. A coating layer (3) is formed on a region of 90% or more of the entire surface of a resin substrate (2). The coating layer (3) is formed on an upper surface (2a), a lower surface (2b), an inner circumference end surface (2c) and an outer circumference end surface (2d) of the substrate (2). Since the substrate (2) is coated with the coating layer (3), a gas is prevented from being discharged from the substrate (2) and the substrate (2) can be prevented from absorbing moisture. Furthermore, adhesiveness between the magnetic layer and the substrate can be improved by forming the magnetic layer on the coating layer (3).

Description

MAGNETIC RECORDING MEDIUM SUBSTRATE, ITS MANUFACTURING METHOD, AND MAGNETIC RECORDING MEDIUM

TECHNICAL FIELD [0001] The present invention relates to a magnetic recording medium substrate used for a substrate of a magnetic disk recording apparatus, a manufacturing method thereof, and a magnetic recording medium, and more particularly to a magnetic recording medium substrate using a resin substrate. .

Background art

[0002] Conventionally, an aluminum substrate or a glass substrate has been used for a magnetic disk recording device used in a computer or the like. A metal magnetic thin film is formed on the substrate, and information is recorded by magnetizing the metal magnetic thin film with a magnetic head (for example, Patent Documents 2 and 3).

[0003] For example, when an aluminum substrate is used, after an aluminum plate is press-molded into a disk shape, the surface is polished with high precision! By applying a polishing process and a cleaning process, the surface is smoothed, and then a nickel-phosphorus (Ni-P) alloy is formed on the surface of the substrate by plating. After that, polishing and texturing are performed, and a magnetic layer of Co alloy is formed by sputtering to produce a magnetic recording medium.

[0004] When a glass substrate is used, a glass material is melted, and the molten glass is press-molded to produce a disk-shaped glass substrate. Then, the surface of the glass substrate is subjected to high-precision polishing IJ 'polishing and cleaning processes to smooth the surface, and then the surface is subjected to chemical strengthening treatment by ion exchange with an alkali molten salt, After passing through a precision cleaning process, a magnetic recording medium is manufactured by applying a texture and forming a Co-based alloy magnetic layer by sputtering.

[0005] By the way, an attempt has been made to employ a resin substrate such as a plastic substrate as the magnetic recording medium substrate. In this case, a magnetic recording medium is manufactured by forming a magnetic layer on a resin substrate.

Patent Document 1: Japanese Patent Laid-Open No. 2003-54965

Patent Document 2: Japanese Patent Laid-Open No. 2003-55001 Patent Document 3: Japanese Unexamined Patent Publication No. 2000-163740

Disclosure of the invention

Problems to be solved by the invention

[0006] However, when a magnetic layer is formed on a resin substrate, gas is released from the resin substrate cover, causing a problem that the magnetic recording medium substrate is contaminated. In addition, since the substrate is made of a resin, the substrate absorbs moisture and moisture, and there is a problem that the shape and quality of the magnetic recording medium substrate may change and the recording / reproducing characteristics may deteriorate ( Moisture resistance issue). As described above, there is a problem in the chemical durability (gas release and moisture resistance) of the resinous resin substrate, so that it is difficult to ensure the reliability of the magnetic recording medium substrate.

[0007] Further, since the adhesion between the resinous substrate and the magnetic layer is low and the thermal expansion coefficient is greatly different, there is a problem that the magnetic layer is easily peeled off from the resinous substrate.

[0008] The present invention solves the above-described problem, and an object thereof is to provide a magnetic recording medium substrate capable of improving the degree of adhesion with a magnetic layer having high chemical durability. . Means for solving the problem

[0009] According to a first aspect of the present invention, a base material made of a resin having a disk shape is used as a substrate, and a coating layer is formed in an area of 90% or more of the entire surface of the substrate. A magnetic recording medium substrate.

[0010] A second aspect of the present invention is the magnetic recording medium substrate according to the first aspect, wherein the coating layer is mainly composed of a metal element.

[0011] A third aspect of the present invention is the magnetic recording medium substrate according to the first or second aspect, wherein the coating layer formed on the main surface of the substrate is composed of a plurality of layers. It is a thing.

A fourth aspect of the present invention is the magnetic recording medium substrate according to any one of the first to third aspects, wherein the coating layer is made of a soft magnetic material or a nonmagnetic material. It is characterized by.

[0013] A fifth aspect of the present invention is a magnetic recording medium substrate according to any one of the first to fourth aspects, wherein the substrate includes a filler material! / It is characterized by scolding.

[0014] A sixth aspect of the present invention is a magnetic recording medium substrate according to the fifth aspect, wherein the filler is a filler. -The material has a particulate shape, and its average particle diameter Df is 0.001 111 to 10 111].

A seventh aspect of the present invention is the magnetic recording medium substrate according to the fifth aspect, wherein the filler material has a particulate shape, the thickness Tc of the coating layer, and the filler material Average particle diameter Df is Tc

It is characterized by satisfying the relationship of / Df> 2.

[0016] An eighth aspect of the present invention is the magnetic recording medium substrate according to the fifth aspect, wherein the filler material has a columnar or fibrous shape, and an average diameter Df is 0. 001 [π

2! ] ~ 50

[/ z m] and the average length Lf is 0.002 [/ ζ πι] to 1000 [/ ζ πι].

[0017] A ninth aspect of the present invention is the magnetic recording medium substrate according to the fifth aspect, wherein the filler material has a columnar or fibrous shape, its average diameter Df, and average The length of Lf is

2

, Lf / Df> 2 is satisfied.

2

[0018] A tenth aspect of the present invention is a magnetic recording medium substrate according to the eighth or ninth aspect, wherein the thickness Tc of the coating layer, the diameter Df of the filler material, and the force Tc / Df2> 2 Meet the relationship

2

It is characterized by that.

An eleventh aspect of the present invention is a magnetic recording medium substrate according to any one of the first to tenth aspects, wherein the coating layer thickness Tc force is 0.001 [/ ζ πι] to 50 It is characterized by [/ ζ πι].

[0020] A twelfth aspect of the present invention is the magnetic recording medium substrate according to any one of the fifth to eleventh aspects, wherein the volume ratio of the filler material to the entire substrate is 0.1 [% ] To 50 [%]. Is.

A thirteenth aspect of the present invention is a magnetic recording medium substrate according to any one of the fifth to twelfth aspects, wherein the surface occupancy of the filler material is 0.1 [%] on the surface of the substrate. ] ~ 50 [

%].

A fourteenth aspect of the present invention is a magnetic recording medium substrate according to any one of the first to thirteenth aspects, wherein a groove is formed on a surface of the substrate. is there.

[0023] A fifteenth aspect of the present invention is the magnetic recording medium substrate according to the fourteenth aspect, wherein the groove is selected from concentric, radial, lattice, dot, or polygonal patterns. This One or more pattern forces are also included.

A sixteenth aspect of the present invention is the magnetic recording medium substrate according to the fifteenth aspect, wherein the pattern is a continuous groove, a discontinuous groove, or a continuous groove and a discontinuous groove. It is characterized by being composed of a combination of

A seventeenth aspect of the present invention is a magnetic recording medium substrate according to any one of the fourteenth to sixteenth aspects, wherein the groove depth Dv is 0.001 [m] to l [m ].

An eighteenth aspect of the present invention is the magnetic recording medium substrate according to any one of the fourteenth to seventeenth aspects, wherein the groove width Wv is 0.001 [/ ζ πι] to 10 [ / ζ πι].

A nineteenth aspect of the present invention is a magnetic recording medium substrate according to any one of the fourteenth to eighteenth aspects, wherein a groove depth Dv, a groove width Wv, and a force Wv> Dv / It is characterized by satisfying the relationship (5).

A twentieth aspect of the present invention is a magnetic recording medium substrate according to any one of the fourteenth to nineteenth aspects, wherein the coating layer thickness Tc, groove depth Dv, and force TcZDv> 2 It is characterized by satisfying this relationship.

[0029] A twenty-first aspect of the present invention is a magnetic recording medium substrate according to any one of the first to twentieth aspects, wherein the surface roughness Ra of the substrate before the coating layer is formed is 1 [ηπ! ] To 1000 [nm], the maximum valley height Rv is 5 to 5000 [nm], and the maximum peak height Rp is 3 [nm] to 3000 [nm].

[0030] A twenty-second aspect of the present invention is a magnetic recording medium substrate according to any one of the first to twenty-first aspects, wherein the thickness Tc of the coating layer and the substrate before the coating layer is formed The surface roughness Ra and force 5 X surface roughness Ra <coating layer thickness Tc <1000 X surface roughness Ra are satisfied.

[0031] A twenty-third aspect of the present invention includes a film forming step of forming a coating layer on a region of 90% or more of the surface of a substrate made of a resin having a disk shape. This is a method for manufacturing a magnetic recording medium substrate.

A twenty-fourth aspect of the present invention is a method for manufacturing a magnetic recording medium substrate according to the twenty-third aspect. A polishing step for polishing the coating layer, wherein the thickness of the coating layer before polishing, the surface roughness Ra of the substrate before the coating layer is formed, and the thickness of the polishing of the coating layer are 5 X surface roughness Ra <polished thickness <0.7 X X satisfies the relationship of the thickness of the coating layer before polishing.

A twenty-fifth aspect of the present invention is a method for manufacturing a magnetic recording medium substrate according to the twenty-fourth aspect, wherein the surface roughness Ra of the substrate after polishing is less than 0.1 l [nm] by polishing. It is characterized by that.

[0034] In a twenty-sixth aspect of the present invention, a base material made of resin having a disk shape is used as a substrate, and a coating layer is formed in an area of 90% or more of the entire surface of the substrate. The magnetic recording medium is characterized in that a magnetic layer is formed on one surface.

The invention's effect

[0035] According to the present invention, since the coating layer is formed in an area of 90% or more of the surface of the resin substrate, and the substrate is covered with the coating layer, the release of gas from the substrate can be prevented. Is possible. Further, since the resinous substrate is covered with the coating layer, moisture absorption by the resinous substrate can be prevented. As described above, since the chemical durability of the resin substrate can be improved, a highly reliable magnetic recording medium can be manufactured by using the resin substrate according to the present invention. .

[0036] Furthermore, by forming a coating layer on a resin-made substrate and forming a magnetic layer on the coating layer, the adhesion between the substrate and the magnetic layer can be improved.

Brief Description of Drawings

1 is a diagram showing a schematic configuration of a magnetic recording medium substrate according to an embodiment of the present invention. FIG. 1A is a perspective view of the substrate, and FIG. 1B is AA of the substrate. It is sectional drawing.

FIG. 2 is a diagram showing a pattern of grooves formed on a substrate, FIG. 2 (a) is a top view of the substrate, and FIG. 2 (b) is a cross-sectional view taken along the line AA of the substrate.

FIG. 3 is a top view showing a pattern of grooves formed on a substrate.

FIG. 4 is a cross-sectional view of a substrate showing a modification of the magnetic recording medium substrate according to the embodiment of the present invention.

FIG. 5 is a schematic view of a substrate showing another modification of the magnetic recording medium substrate according to the embodiment of the present invention. It is sectional drawing.

FIG. 6 is an enlarged sectional view of a mold.

Explanation of symbols

[0038] 1, 10, 20 Substrate for magnetic recording medium

2 Board

3, 4, 5 coating layer

21A, 21B, 22, 23, 24 groove

100 mold

101 Convex

102 Flat part

BEST MODE FOR CARRYING OUT THE INVENTION

A magnetic recording medium substrate according to an embodiment of the present invention will be described with reference to FIG.

. FIG. 1 is a diagram showing a schematic configuration of a magnetic recording medium substrate according to an embodiment of the present invention. FIG. 1 (a) is a perspective view of the substrate, and FIG. 1 (b) is a cross-sectional view taken along the line AA of the substrate. It is.

[0040] The substrate 2 has a disk shape and has a hole in the center. A covering layer 3 is formed on the surface of the substrate 2 to form a magnetic recording medium substrate 1. Substrate 2 is made of resin.

As shown in FIG. 1 (b), the coating layer 3 is formed on the entire surface of the substrate 2. That is, the upper surface 2a, the lower surface 2b, the inner peripheral end surface 2c, and the outer peripheral end surface 2d of the base plate 2 are covered with the coating layer 3. As described above, since the surface of the substrate 2 is covered with the coating layer 3, it is possible to prevent the gas from being released from the substrate 2. Furthermore, moisture absorption by the substrate 2 can be prevented, and moisture resistance can be improved. As a result, the dimensional change of the substrate 2 due to moisture absorption can be prevented, and positional deviation from the magnetic head can be prevented. As described above, according to the magnetic recording medium substrate 1 according to this embodiment, chemical durability (gas emission and moisture resistance) can be improved.

In addition, by forming a magnetic layer on the coating layer 3, it is possible to increase the degree of adhesion between the magnetic layer and the substrate, rather than forming the magnetic layer directly on the substrate 2.

In this embodiment, the coating layer 3 is formed on the entire surface of the substrate 2 to cover the entire surface. The force covered by the layer 3 Since the covering layer 3 is formed in a region of 90% or more of the entire surface, the chemical durability of the magnetic recording medium substrate 1 can be improved.

[0044] The thickness Tc of the coating layer 3 is preferably 0.001 [/ ζ πι] to 50 [/ ζ πι], preferably the upper surface 2a, the lower surface 2b, the inner peripheral end surface 2c, and the outer peripheral surface. The thickness of the covering layer on each face of the end face 2d may be the same or different. For example, the thickness of the coating layer 3 formed on the upper surface 2a is equal to the thickness of the coating layer 3 formed on the surface other than the upper surface 2a, for example, the coating layer 3 formed on the lower surface 2b. It's okay or different. Thus, even if the thickness of the coating layer 3 on each surface is different, the chemical durability of the magnetic recording medium substrate 1 can be improved.

Next, the material of the substrate 2 made of resin is described. For the substrate 2, various types of resin can be used in addition to thermoplastic resin, thermosetting resin, or active ray curable resin.

[0046] For example, the substrate 2 made of resin has a thermoplastic resin such as polycarbonate, polyetheretherketone resin (PEEK resin), cyclic polyolefin resin, methallyl styrene resin (MS resin), Polystyrene resin (PS resin), polyetherimide resin (PEI resin), ABS resin, polyester resin (PET resin, PBT resin, etc.), polyolefin resin (PE resin, PP resin, etc.) ), Polysulfone resin, polyether sulfone resin (PES resin), polyarylate resin, polyphenylene sulfide resin, polyamide resin, acrylic resin, and the like. Examples of thermosetting resins include phenol resin, urea resin, unsaturated polyester resin (BMC resin, etc.), silicon resin, urethane resin, epoxy resin, polyimide resin, polyamide Imido resin or polybenzimidazole resin can be used. In addition, polyethylene naphthalate resin (PEN resin) can be used!

[0047] As the actinic radiation curable resin, for example, an ultraviolet curable resin is used. Examples of the ultraviolet curable resin include, for example, an ultraviolet curable acrylic urethane resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, Examples thereof include an ultraviolet curable epoxy resin, an ultraviolet curable silicon resin, and an ultraviolet curable acrylic resin. [0048] In addition, it is preferable to accelerate the curing reaction using a photoinitiator when curing is performed by irradiating the applied layer with active rays. At this time, a photosensitizer may be used in combination.

[0049] When oxygen in the air suppresses the curing reaction, active rays can be irradiated, for example, in an inert gas atmosphere in order to reduce or remove the oxygen concentration. As the actinic ray, infrared rays, visible light, ultraviolet rays, and the like can be appropriately selected. However, ultraviolet rays are particularly preferred, but are not particularly limited. In addition, the curing reaction may be strengthened by heating during active ray irradiation or before and after.

[0050] Furthermore, the substrate 2 made of resin may use a liquid crystal polymer, an organic Z inorganic hybrid resin (for example, a polymer component incorporating silicon as a skeleton), or the like. Note that the resin listed above is an example of the resin used for the substrate 2, and the substrate according to the present invention is not limited to these resins. Two or more kinds of resin may be mixed to form a resin-made substrate, or a substrate in which different components are adjacent to each other as separate layers.

[0051] Further, it is desirable that the resin as a base material has a heat-resistant temperature or a glass transition temperature Tg as high as possible. Since the magnetic layer is formed on the resin substrate 2 by sputtering, it is desirable that the heat resistant temperature or the glass transition temperature Tg is equal to or higher than the sputtering temperature. For example, it is desirable to use a resin having a heat-resistant temperature or a glass transition temperature Tg of 150 ° C or higher, more preferably 200 ° C or higher.

[0052] Typical heat-resisting temperature or glass transition temperature Tg of 150 ° C or higher includes heat-resistant polycarbonate, silicon resin, Teflon (registered trademark) resin, phenol filler filled with inorganic filler, melanin Resins such as epoxy, polysulfide sulfide, unsaturated polyester, polyethersulfone resin (PES resin), polyetherimide resin (PEI resin), polyamideimide resin, polyimide resin, Nzoimidazole resin, BMC resin, or liquid crystal polymer. More specifically, polyethersulfone resin (PES resin), Udel (Solveia Devast Polymers), polyetherimide resin (PEI resin), Ultem (Japan GE Plastics), polyamideimide resin As fat, Torlon (Solveia Devast Polymers), polyimide resin (thermoplastic), Aurum (Mitsui Chemicals), polyimide (thermosetting), Upilex (Ube Industries), or polybenzoimidazo PBlZCelazole (Clariant Japan) is an example of lube. Liquid crystal polymers include SUMIKASUPER LCP (Sumitomo Chemical) and polyetheretherketone as Victorex (Vitatrex MC).

The covering layer 3 includes a metal layer, a magnetic layer (paramagnetic layer, soft magnetic layer, or ferromagnetic layer), an oxide layer such as a glass layer and a ceramic layer, or an inorganic layer and an organic layer. These composite layers (hybrid layers) are used. Specific components of the coating layer include Mg (magnesium), Ca (calcium), Sr (strontium) Ba (barium), Ti (titanium), Sc (scandium), V (vanadium), Cr (chromium), Mn ( Manganese), Fe (iron), Co (cobalt), Ni (nickel), Cu (copper), Zn (zinc), A1 (aluminum), Si (silicon), P (phosphorus), Ga (gallium), Ge ( Germanium), As (arsenic), Se (selenium), Y (yttrium), Zr (zirconium), Nb (niobium), Mo (molybdenum), Ru (ruthenium) Rh (rhodium), Pd (palladium), Ag ( Silver), Cd (cadmium), In (indium), Sn (tin), Sb (antimony), Te (tellurium), La (lanthanum), Ce (cerium), Pr (prasedium), Nd (neodymium), Pm (Promethium), Sm (Samarium), Eu (Europium , Gd (gadrium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium), Hf (hafnium), Ta ( Tantalum), W (tungsten), Re (rhenium), Os (osmium), Ir (iridium), Pt (platinum), Au (gold), T1 (thallium), Pb (lead), Bi (bismuth), Po ( Porous)).

[0054] The coating layer 3 can be formed on the surface of the substrate 2 by a plating method such as electric plating or chemical plating. In addition, it can be formed by sputtering, vacuum deposition, CVD method, or the like. Further, it may be formed by a coating method such as a bar coating method, a dip coating (dipping and pulling up) method, a spin coating method, a spray method, or a printing method.

When a magnetic recording medium is manufactured using the magnetic recording medium substrate 1, a magnetic layer is formed on the coating layer 3 formed on the upper surface 2a to obtain a magnetic recording medium. In this case, the coating layer and the magnetic layer may be produced continuously, or if necessary, the magnetic layer may be produced subsequently after treating the surface of the coating layer. For example, the coating layer 3 formed on the upper surface 2a is polished, and a magnetic layer such as a Co-based alloy is formed on the polished coating layer by sputtering or the like to obtain a magnetic recording medium. [0056] Also, in a perpendicular magnetic recording medium that is highly expected as a high-density technology, it is necessary to arrange magnetic materials perpendicular to the substrate surface. To that end, a soft magnetic layer is required between the magnetic layer and the substrate. Need to form. A typical alloy for this soft magnetic layer is a nickel-cobalt (Ni-Co) alloy. By using a Ni—Co alloy as the covering layer 3, it can also function as a soft magnetic layer in a perpendicular magnetic recording medium.

[0057] It is desirable to use a resin having good adhesion to the coating layer 3 formed on the surface for the substrate 2. For example, a resin having a polar group on the surface, a resin having a large surface roughness Ra, a resin containing a filler material, a resin having a groove on the surface, or the like is used as the material of the substrate 2. As a result, the adhesion between the substrate 2 and the coating layer 3 can be increased.

[0058] For example, if the surface roughness Ra of the substrate 2 is increased, the area that adheres to the coating layer 3 formed on the surface increases, so that the adhesion between the substrate 2 and the coating layer 3 is increased. Is possible. The surface roughness Ra of the substrate 2 obtained by molding can be increased by adjusting the surface roughness Ra of the mold used when the substrate 2 is produced by injection molding or cast molding. Even if the surface roughness Ra of the substrate 2 is increased, the required surface roughness Ra can be obtained by polishing the coating layer 3 formed on the surface.

[0059] Specifically, in the substrate 2 before the coating layer 3 is formed, the surface roughness Ra specified by JIS B0601 is 1 [ηπ! ] ~ 1000 [nm], maximum valley height Rv is 5 to 5000 [nm], maximum peak height Rp is 3 [nm] to 3000 [nm]! / ,. Thus, by adjusting values such as the surface roughness Ra, it is possible to increase the degree of adhesion between the substrate 2 and the coating layer 3.

[0060] Further, it is preferable that the relationship between the thickness of the coating layer 3 and the surface roughness Ra of the substrate 2 before forming the coating layer 3 satisfies the following formula (1):

[0061] Formula (1)

5 X Surface roughness Ra <Thickness of coating layer 3 1000 X Surface roughness Ra

Since the coating layer 3 is polished before the magnetic layer is formed on the coating layer 3, the thickness of the coating layer 3 is preferably thicker than 5 XRa in consideration of the amount of polishing.

[0062] When the coating layer 3 is polished, the thickness of the coating layer 3, the surface roughness Ra of the substrate 2 before forming the coating layer 3, and the thickness of polishing the coating layer 3 are as follows: It is preferable to satisfy equation (2). [0063] Formula (2)

5 X Surface roughness Ra <Polished thickness 0.7 X Thickness of X coating layer 3

The surface roughness Ra of the coated layer 3 after polishing is preferably less than 0.1 [nm].

[0064] When the filler contains a filler, the filler material may have any shape such as a spherical shape, a cylindrical shape, an uneven shape, an elliptical shape, or a fiber shape (fiber shape). Also, the filler material can be included along one direction, which means that it is included in a random direction.

[0065] By thus including the filler material in the base resin, a part of the filler material protrudes from the surface of the substrate 2, and the protrusion makes the surface shape uneven. As a result, the degree of adhesion between the substrate 2 and the coating layer 3 can be improved. The degree of unevenness can be controlled by selecting particles (for example, particle type, particle size, particle addition amount), etching, heating, energy particle irradiation, and combinations thereof.

[0066] For example, when a particulate filler material is used, it is preferable that the average particle diameter Df of the filler material is 0.001 [m] to 10 [m]! /. By using such a filler material, moderate irregularities are formed on the surface of the substrate 2, and the degree of adhesion between the coating layer 3 and the substrate 2 can be increased by the irregularities.

[0067] Further, it is preferable that the relationship between the average particle diameter Df of the filler material and the thickness Tc of the coating layer 3 satisfies the following formula (3).

[0068] Formula (3)

Covering layer 3 thickness Tc, average particle size Di> 2

This makes it possible to increase the degree of adhesion between the coating layer 3 and the substrate 2.

[0069] When a fibrous or columnar filler material is used, the average diameter Df of the column is 0.0.

2

It is preferable that the average length Lf is in the range of 01 [m] to 50 [m] and the average length Lf is 0.002 [m] to: LOOO [m].

[0070] Formula (4)

Lf / Df> 2

2

By using such a filler material, moderate irregularities are formed on the surface of the substrate 2, and the degree of adhesion between the coating layer 3 and the substrate 2 can be increased by the irregularities. [0071] Further, the relationship between the average diameter Df of the filler material and the thickness Tc of the coating layer 3 is expressed by the following equation (5).

2

It is preferable to satisfy.

[0072] Formula (5)

Covering layer 3 thickness Tc, average diameter Df> 2

2

[0073] Further, it is preferable that the volume ratio of the filler material to the whole substrate 2 is 0.1 [%] to 50 [%] regardless of the shape of the filler material.

[0074] The surface occupancy of the filler material is preferably 0.1 [%] to 50 [%]. Furthermore, it is preferred that the surface occupancy is smaller than the volume fraction! (Surface occupancy fraction). As a result, by etching the substrate 2, the filler material on the upper surface 2a disappears and irregularities are formed on the upper surface 2a.

[0075] As a material of the filler material, metal, oxide, sulfide, carbonate, phosphorus oxide, fluoride, glass, glass fiber, carbon fiber, or the like is used. Specifically, the filler material is Si (silicon), A1 (aluminum), C (carbon), Sn (tin), Zn (zinc), Ti (titanium), In (indium), Mg (magnesium). Pd (palladium), Ba (barium), La (lanthanum), Ta (tantanole), Mo (molybdenum), W (tungsten), V (vanadium), or Sr (strontium) can be used. Furthermore, compounds containing these as main components, for example, oxides, sulfides, carbonates, phosphorus oxides, fluorides, and the like may be used. Specifically, SiO, Al O, TiO, SrCO, C, AlPO, CaCO, IT

2 2 3 2 3 4 3

0, ZnS, MgF, etc. are used as filler materials.

2

[0076] The above-mentioned examples of the material of the filler material are examples of the inorganic material, but organic, inorganic composite materials may be used as the material of the filler material. May be used in combination!

[0077] When grooves are provided on the surface of the substrate 2, the grooves form a pattern such as concentric circles, radial shapes, lattice shapes, dot shapes, or polygonal shapes. The groove may be continuous or may be interrupted and discontinuous. In addition, when forming a groove in a dot shape, the dot groove is formed by forming a recess at a position distant from each other. Further, a groove formed by combining a plurality of types of patterns may be formed. For example, with concentric patterns Grooves can be formed by combining radial patterns, or multiple types of continuous and discontinuous patterns can be combined.

Here, the pattern of grooves formed in the substrate will be described with reference to FIG. Fig. 2 is a diagram showing the notches of the grooves formed in the substrate, and Fig. 2 (a) is a top view of the substrate.

2 (b) is a cross-sectional view taken along the line AA of the substrate.

[0079] As shown in the top view of FIG. 2 (a), the substrate 2 is formed with concentric grooves 21A and grooves 21B extending radially from the center. In this example, three concentric grooves 21A are formed at equal intervals, and eight radial grooves 21B are formed every 45 °.

The number of IBs and the interval between the grooves may be appropriately changed depending on conditions such as the size and material of the substrate 2.

[0080] The widths of the grooves 21A and 21B may be the same or different. Further, the interval between the grooves 21A may be different depending on the groove. The angle formed by the grooves 21B may be different depending on the groove.

[0081] In the example shown in Fig. 2, two types of grooves, concentric grooves 21A and radial grooves 21B, are formed on the base plate 2, but one of the grooves may be formed. Good!

[0082] By forming grooves on the surface of the substrate 2 as described above, it is possible to increase the degree of adhesion between the substrate 2 and the coating layer 3. In the example shown in FIG. 2, the groove is formed only on one surface of the substrate 2, but the groove may be formed on both surfaces.

[0083] The depth Dv (depth of the recess) of the grooves 21A and 21B is preferably 0.001 [m] to l [m]. The width Wv (the diameter of the recess) of the grooves 21A and 21B is preferable. It is preferable that it is 1S 0.001 [m]-10 [m].

[0084] Further, it is preferable that the relationship between the depth Dv of the grooves 21A and 21B and the width Wv of the grooves 21A and 21B satisfies the following expression (6).

[0085] Formula (6)

Width Wv> Depth DvZ5

By using a substrate having such a groove (uneven pattern) formed on the surface, the degree of adhesion between the coating layer 3 and the substrate 2 can be increased.

[0086] The relationship between the depth Dv of the grooves 21A and 21B and the thickness Tc of the coating layer 3 is expressed by the following equation (7). It is preferable to satisfy.

[0087] Formula (7)

Covering layer 3 thickness TcZ groove depth Dv> 2

Another pattern of the groove will be described with reference to FIG. FIG. 3 is a top view showing a pattern formed on the substrate.

[0088] For example, as shown in FIG. 3 (a), a lattice-like pattern is formed by forming grooves 22 orthogonal to each other on the substrate 2. The number of the grooves 22 and the interval between the grooves 22 may be appropriately changed depending on conditions such as the size and material of the substrate. The widths of the grooves 22 may be the same or different. Further, as shown in FIG. 3B, a groove 23 having a hexagonal pattern force may be formed in the substrate 2. Further, as shown in FIG. 3C, a groove 24 having a triangular pattern force may be formed in the substrate 2. In the example shown in FIG. 3, the groove pattern is a triangular shape, a quadrangular shape, or a hexagonal shape, but may be a pattern having an octagonal shape or more.

[0089] It is preferable that the grooves 22, 23, and 24 shown in FIG. 3 also satisfy the relationships of the above formulas (6) and (7).

When forming the groove on the substrate 2, it is possible to form the groove directly on the substrate 2 at the time of forming the substrate by forming an original plate of the groove pattern on the mold. Further, when the groove is formed after the substrate 2 is formed, it can be formed by using a technique such as micromachining, a drawing method such as lithograph, or a chemical etching method.

[0091] Substrate 2 made of resin is molded using a mold having a shape corresponding to substrate 2, such as an injection molding method, a casting molding method, a sheet molding method, an injection compression molding method, or a compression molding method. Can be manufactured by law. Further, if necessary, the substrate 2 may be manufactured by cutting, punching, or press-molding the formed substrate.

[0092] Further, by molding the substrate 2 by the injection molding method or the like, at least one of the inner diameter size, the outer diameter size, the inner peripheral end portion shape, or the outer peripheral end portion shape of the substrate 2 is simultaneously performed. Can be formed. In other words, molds used in the injection molding method, etc., are manufactured in accordance with the inner and outer diameter dimensions of the substrate 2, and the inner and outer diameter dimensions are completed during resin molding by using these molds. Will be. In addition, a mold is manufactured according to the shape of the inner peripheral end of the substrate 2 and the shape of the outer peripheral end, and by using the mold, the shape of the inner peripheral end and the outer periphery The shape of the end is formed at the time of resin molding.

[0093] The surface roughness Ra of the mold surface used for molding is 1 [ηπ! ] ~ 1000 [nm] and maximum peak height Rp is preferably 5 [nm] ~ 5000 [nm]. By manufacturing the substrate 2 with this mold, moderate irregularities are formed on the surface of the substrate 2, and the adhesion between the substrate 2 and the coating layer 3 can be increased by the irregularities.

[0094] Further, the surface of the mold may be composed of a smooth portion and a convex portion. This mold will be described with reference to FIG. Fig. 6 is an enlarged sectional view of the mold. As shown in FIG. 6, a convex part 101 protruding outward is formed on the surface of the mold 100, and a flat part 102, which is a flat surface, is formed between the convex part 101 and the convex part 101. ing. By forming the substrate 2 using this mold 100, irregularities are formed on the upper surface 2a of the substrate 2, and the adhesion between the substrate 2 and the coating layer 3 can be increased by the irregularities.

[0095] In addition, it is preferable that the area S on the bottom surface of the protrusion 101 is 100 [nm ² ] to 1000000 [nm ² ]. The ratio force of the area S of all the protrusions 101 to the entire surface of the substrate is 0.001. [%] To 50 [%] is preferable. By molding the substrate 2 using such a mold, moderate irregularities are formed on the surface of the substrate 2, and the degree of adhesion between the substrate 2 and the coating layer 3 can be increased by the irregularities.

[0096] Further, when a groove having a predetermined pattern is formed on the surface of the substrate 2 as in the substrate shown in FIGS. 2 and 3, by forming a pattern original on the mold 100, the substrate is molded. A groove can be directly formed in the substrate 2. For example, the grooves 21A and 21B shown in FIG. 2 can be formed by changing the pattern of the convex portion 101 to a pattern in which a concentric pattern and a radial pattern are combined. Further, the groove 22 shown in FIG. 3 (a) can be formed by making the pattern of the convex portions 101 into a pattern that is perpendicular to each other. Furthermore, by making the pattern of the convex portion 101 a hexagonal pattern or a triangular pattern, a hexagonal or triangular groove can be formed on the substrate 2.

Further, the substrate 2 may be subjected to chemical treatment or physical treatment to form irregularities on the surface of the substrate 2, and then the coating layer 3 may be formed on the substrate 2. For example, unevenness is formed on the surface of the substrate 2 by performing etching, spraying of a blast material, laser processing, or machining. In this way, the surface of the substrate 2 is recessed by chemical treatment or physical treatment. By forming the projections, the adhesion between the substrate 2 and the coating layer 3 can be increased.

[0098] Note that examples of the etching method include chemical etching, physical etching, and physical chemical etching. Chemical etching is a method of selectively etching a removal target using a chemical reaction. Physical etching is a method of etching a removal target by causing accelerated argon ions to collide with the etching target surface. Examples of physical etching include ion milling. In addition, physicochemical etching is a method in which anisotropic etching is performed by using a chemical reaction between radicals (activated molecules and atoms having no charge) and the material to be etched and ion irradiation. is there . Examples of physicochemical etching include RIE (Reactive Ion Etching).

[0099] After preparing the resin substrate 2, the coating layer 3 is formed in a region of 90% or more with respect to the entire surface of the substrate 2 by a film forming method such as a plating method. Thereafter, the coating layer 3 is polished, and a magnetic layer is formed on the coated layer 3 after polishing to obtain a magnetic recording medium. For example, a magnetic layer is formed on the covering layer 3 formed on the upper surface 2a. Further, a magnetic layer may be formed on the covering layer 3 formed on the upper surface 2a and the lower surface 2b. In this way, a magnetic layer may be formed on only one side of the magnetic recording medium substrate 1 or a magnetic layer may be formed on both sides.

[0100] Further, the above description has been made by taking as an example a substrate composed of a single resin. However, the substrate is not limited to one composed of a single resin, and may be made of metal or metal. It may be configured by coating the surface of a non-magnetic material such as glass with a resin layer. In this case, as the nonmagnetic material coated with the resin, various materials applicable as a substrate such as a resin, metal, ceramics, glass, glass ceramics, or an organic-inorganic composite material can be used.

(Modification)

Next, modified examples of the magnetic recording medium substrate according to the embodiment of the present invention will be described with reference to FIGS. 4 and 5. FIG. FIG. 4 is a cross-sectional view of a substrate showing a modification of the magnetic recording medium substrate according to the embodiment of the present invention. FIG. 5 is a cross-sectional view of a substrate showing another modification of the magnetic recording medium substrate according to the embodiment of the present invention.

(Modification 1) First, Modification 1 will be described with reference to FIG. In the magnetic recording medium substrate 10 according to Modification 1, the coating layer 4 is formed on the upper surface 2a and the lower surface 2b of the disk-shaped substrate 2, but the coating layer is not formed on the inner peripheral end surface 2c and the outer peripheral end surface 2d. It's formed!

[0101] In this way, even if no coating layer is formed on the entire surface of the substrate 2, it is possible to suppress the release of gas from the substrate 2, prevent moisture absorption by the substrate 2, and improve moisture resistance. It becomes possible to improve. Further, by forming a magnetic layer on the coating layer 4, it is possible to increase the degree of adhesion between the magnetic layer and the substrate.

[0102] It should be noted that, in this modified example 1, a coating layer is formed on both end surfaces of the inner peripheral end surface 2c and the outer peripheral end surface 2d, but the inner peripheral end surface 2c or the outer peripheral end surface 2d is shifted to one end surface. A coating layer may be formed on the surface. That is, a coating layer may be formed on the upper surface 2a, the lower surface 2b, and the inner peripheral end surface 2c, or a coating layer may be formed on the upper surface 2a, the lower surface 2b, and the outer peripheral end surface 2d.

(Modification 2)

Next, Modification 2 will be described with reference to FIG. In the magnetic recording medium substrate 20 according to Modification 2, a coating layer 3 (hereinafter sometimes referred to as a “first coating layer”) is formed on the entire surface of the disk-shaped substrate 2. Further, another coating layer 5 (hereinafter sometimes referred to as “second coating layer”) is formed on the coating layer 3 on the upper surface 2a on which the magnetic layer is formed. That is, two coating layers are formed on the upper surface 2a. The upper surface 2a corresponds to the “main surface” of the present invention. Then, a magnetic layer is formed on the covering layer 5 formed on the upper surface 2a to obtain a magnetic recording medium.

[0103] The coating layer 3 as the first coating layer is made of a material having a high degree of adhesion to the substrate 2 made of resin, and the coating layer 5 as the second coating layer is adhered to the magnetic layer. Use a high degree of material. As a result, the adhesion between the substrate 2 and the coating layer 3 can be increased, and the adhesion between the coating layer 5 and the magnetic layer can be increased. As a result, it is possible to prevent the coating layers 3 and 5 and the magnetic layer from peeling off.

[0104] Further, similarly to the first modification shown in FIG. 4, it is not necessary to form a coating layer on the inner peripheral end face 2c and the outer peripheral end face 2d. In this case, the coating layer 5 is formed on the coating layer 4 formed on the upper surface 2a, and the coating layer 4 is formed on the lower surface 2b.

[0105] Two coating layers may be formed on both sides. In this case, the upper surface 2a has a first coating. A coating layer 5 as a second coating layer is formed on the coating layer 3 as a layer, and a second coating layer is formed on the coating layer 3 as the first coating layer on the lower surface 2b. A certain coating layer 5 is formed. By forming two coating layers on both surfaces of the substrate 2 in this way, when forming a magnetic layer on both surfaces, the degree of adhesion between the substrate 2 and the coating layer is increased, and the coating layer and the magnetic layers on both surfaces are also formed. It is possible to increase the degree of adhesion to the. When the coating layers are formed on both surfaces of the substrate 2, the upper surface 2a and the lower surface 2b correspond to the “main surface” of the present invention.

[0106] In Modified Example 2, two coating layers are formed, but three or more coating layers may be formed. Further, a gradient component layer, which is a single coating layer and gradually changes its component in the thickness direction, may be formed on the substrate 2. For example, a layer having a high degree of adhesion with the resin is formed on the side in contact with the substrate 2 and a layer having a high degree of adhesion with the magnetic layer is formed on the outermost surface side. As a result, the adhesion between the substrate 2 and the coating layer can be increased, and the adhesion between the coating layer and the magnetic layer can be increased, thereby preventing the coating layer and the magnetic layer from peeling off.

[0107] Also, in Modification 1 and Modification 2, grooves having a predetermined pattern as shown in FIGS. 2 and 3 may be formed.

[Example]

Next, specific examples of the present invention will be described.

(Example 1)

In Example 1, a specific example of the magnetic recording medium substrate 1 shown in FIG. 1 will be described. In Example 1, the coating layer 3 was formed on the entire surface of the substrate 2 and evaluated for adhesion and chemical durability.

(Substrate 2 molding)

Polyimide was used as a substrate material, and a resin substrate 2 was produced by injection molding. Aurum (made by Mitsui Engineering Co., Ltd.) was used as a polyimide. The dimensions of this substrate 2 are shown below.

[0108] Outer diameter: 27.4 [mm]

Substrate 2 thickness: 0.4 [mm]

Surface roughness Ra: 5nm

(Deposition of coating layer 3)

A Ni layer was formed on the entire surface of the substrate 2 by sputtering the substrate 2. Thereafter, further sputtering was performed to form a nickel monophosphorus (Ni-P) alloy layer (hereinafter referred to as “NiP layer”) on the Ni layer. The thickness of this NiP layer was 10 [nm]. These M layer and NiP layer correspond to the coating layer 3 formed on the substrate 2.

(Evaluation of adhesion of coating layer 3)

After the coating layer 3 was formed on the substrate 2, the degree of adhesion of the coating layer 3 was evaluated. Here, a substrate tape peeling test was adopted as a method for evaluating the degree of adhesion. This base tape peeling test was performed in accordance with the method specified in Part 5 (Mechanical properties of paint film), Section 6 (Adhesiveness: Cross-cut method) of JIS K 5600 (General paint test method). Then, 11 cut lines that reach the substrate 2 made of resin so as to be orthogonal to each other at intervals of 1 mm are attached to the covering layer 3, and then the cellophane adhesive tape (manufactured by Nichiban Co., Ltd.) is formed on the base. LP-24) was adhered, and the tape was immediately peeled off to confirm that the covering layer 3 was peeled off. Judgment of adhesion shall be good if it falls under Category 0, Category or Category 2 according to Table 1 `` Classification of test results '' described in JIS K 5600 Part 5 Section 6 8.3. Those that fall under the category were implemented as defective.

[0109] As a result of performing this peeling test, it was confirmed that in Example 1, the adhesion of the coating layer 3 to the substrate 2 was good.

(Evaluation of chemical durability)

Furthermore, chemical durability (humidity resistance) was evaluated. The substrate 2 on which the coating layer 3 is formed is kept in a constant temperature and humidity chamber at a temperature of 60 ° C and a relative humidity of 95% for 1 week, and the mass of the substrate 2 before and after the test is measured, and the chemical durability (moisture resistance) Evaluation). The chemical durability was judged as good if the mass change rate was less than 0.1% and bad if it was 0.1% or more.

[0110] As a result of this test, it was confirmed that the substrate 2 on which the coating layer 3 was formed exhibited good chemical durability.

(Polishing process)

After the coating layer 3 was formed, the surface of the coating layer 3 was polished. In this polishing step, a slurry mainly composed of kodiamond was used as an abrasive. The surface roughness Ra of the polished magnetic recording medium substrate was 0.4 [nm]. (Deposition of magnetic layer)

After the polishing step, a magnetic layer of a Co-based alloy was formed on the coating layer 3 formed on the surface 2a by sputtering to produce a magnetic recording medium.

(Evaluation of magnetic layer adhesion)

After the magnetic layer was formed on the coating layer 3, the adhesion of the magnetic layer was evaluated. The degree of adhesion of the magnetic layer was evaluated by the same method as the method for evaluating the degree of adhesion of the coating layer 3. As a result of this test, it was confirmed that the adhesion of the magnetic layer to the coating layer 3 and the substrate 2 was good.

[0111] As described above, according to the magnetic recording medium substrate 1 of Example 1, the chemical durability can be increased, and the adhesion between the magnetic layer and the substrate can be increased.

[0112] In Example 1, polyimide was used as the material for the substrate 2 made of resin, but the same effect can be obtained by using other resins described in the above embodiment. Further, the same effect can be obtained by laminating a layer having another component force such as a nickel-cobalt layer having a NiP layer as a coating layer.

(Example 2)

In Example 2, a specific example of the magnetic recording medium substrate 10 shown in FIG. 4 will be described. In Example 2, the coating layer 4 was formed on the upper surfaces 2a and 2b of the substrate 2, and the adhesion and chemical durability were evaluated.

(Substrate 2 molding)

[0113] Outer diameter: 21.6 [mm])

Substrate 2 thickness: 0.3 [mm]

Surface roughness Ra: 30nm

(Deposition of coating layer 4)

By sputtering the substrate 2, Ni layers were formed on the surfaces 2a and 2b of the substrate 2. Thereafter, further sputtering was performed to form a nickel-phosphorus (Ni—P) alloy layer (hereinafter referred to as “NiP layer”) on the Ni layer. The thickness of this NiP layer is 100 [nm] I got it. These Ni layer and NiP layer forces correspond to the coating layer 4 formed on the substrate 2. Thus, in Example 2, the coating layer 4 was formed on the surfaces 2a and 2b of the substrate 2, and the coating layer was not formed on the inner peripheral end surface 2c and the outer peripheral end surface 2d of the substrate 2. In this example, the coating layer 4 is formed in an area of 90% or more of the entire surface of the substrate.

(Evaluation of adhesion of coating layer 4)

After the coating layer 4 was formed on the substrate 2, the adhesion of the coating layer 4 was evaluated in the same manner as in Example 1. As a result, it was confirmed that the adhesion of the coating layer 4 to the substrate 2 was good.

(Evaluation of chemical durability)

Further, the chemical durability (moisture resistance) was evaluated in the same manner as in Example 1. As a result, it was confirmed that the substrate 2 provided with the coating layer 4 showed good chemical durability.

(Polishing process)

After the coating layer 3 was formed, the surface of the coating layer 3 was polished. In this polishing step, a slurry containing colloidal silica as a main component was used as an abrasive. The surface roughness Ra of the polished magnetic recording medium substrate was 0.2 [nm].

(Deposition of magnetic layer)

After the polishing step, a magnetic layer of a Co-based alloy was formed on the coating layer 4 formed on the surface 2a by sputtering to produce a magnetic recording medium.

(Evaluation of magnetic layer adhesion)

After the magnetic layer was formed on the coating layer 4, the adhesion of the magnetic layer was evaluated by the same method as in Example 1. As a result, it was confirmed that the adhesion of the magnetic layer to the coating layer 4 and the substrate 2 was good.

[0114] As described above, the chemical durability can be improved without forming the coating layer 4 only on the upper surface 2a and the lower surface 2b and forming the coating layer on the outer peripheral end surface 2c and the outer peripheral end surface 2d. In addition, the adhesion between the magnetic layer and the substrate can be increased.

[0115] In addition to Example 1 and Example 2 above, the coating layer is formed in a region of 90% or more on the entire surface of the substrate 2, whereby the chemical durability can be increased, and the magnetic layer and The degree of adhesion with the substrate can be increased. (Comparative Example 1)

Next, a comparative example for Example 1 and Example 2 will be described. In this comparative example, a magnetic recording medium was manufactured by forming a Co-based alloy magnetic layer on a resin (polyimide) substrate by sputtering. Thus, in the comparative example, the magnetic layer was formed directly on the resin-made substrate without forming the coating layer.

(Substrate molding)

Polyimide was used as the substrate material, and a resin-made substrate was produced by injection molding. Aurum (Mitsui Engineering Co., Ltd.) was used as the polyimide. The dimensions of this substrate are shown below.

Outer diameter: 27.4 [mm]

Substrate thickness: 0.4 [mm]

Surface roughness Ra: 5nm

(Deposition of magnetic layer)

A magnetic layer of a Co-based alloy was formed on the resin substrate by sputtering to produce a magnetic recording medium.

(Evaluation of chemical durability)

In the same manner as in Example 1 and Example 2, chemical durability (moisture resistance) was evaluated. As a result, it was confirmed that the substrate on which the magnetic layer was formed had a mass increase rate of 0.1% or more, and the chemical durability as a magnetic recording medium was not good.

(Evaluation of magnetic layer adhesion)

After the magnetic layer was formed on a resin substrate, the adhesion of the magnetic layer was evaluated in the same manner as in Example 1 and Example 2. As a result, the adhesion degree of the magnetic layer to the substrate falls under Category 4 in Table 1 of JIS K 5600, and it was confirmed that the adhesion degree was not sufficient. (Comparative Example 2)

A sample was prepared in the same manner as in Example 1 except that the coating layer 3 was formed on 90% of the upper surface 2a and 90% of the lower surface 2b of the substrate 2 in Example 1. That is, in this example, the coating layer 3 is formed in 90% of the area on the upper surface 2a and the lower surface 2b of the substrate 2, but the coating layer 3 is formed on all of the inner peripheral end surface 2c and all of the outer peripheral end surface 2d. Therefore, the covering layer is formed only in an area of less than 90% of the entire surface of the substrate 2. [0117] In this comparative sample, it was confirmed that the coating layer had good adhesion, but the chemical durability was evaluated as poor.

[0118] As described above, since 90% or more of the entire surface of the substrate 2 is covered with the coating layer, chemical durability can be improved. Furthermore, by forming a magnetic layer on the covering layer, it is possible to increase the degree of adhesion between the magnetic layer and the substrate rather than directly forming the magnetic layer on the substrate. That is, according to the present invention, it is possible to obtain a magnetic recording medium substrate that satisfies both adhesion and chemical durability at the same time.

Claims

The scope of the claims

[1] A substrate for a magnetic recording medium, wherein a base material made of a resin having a disk shape is used as a substrate, and a coating layer is formed in an area of 90% or more of the entire surface of the substrate.

[2] The magnetic recording medium substrate according to claim 1, wherein the coating layer contains a metal element as a main component.

[3] The magnetic recording medium substrate according to [1] or [2], wherein the coating layer formed on the main surface of the substrate is composed of a plurality of layers. .

[4] The magnetic recording medium substrate according to any one of [1], [3], [3] and [3], wherein the coating layer is made of a soft magnetic material or a non-magnetic material.

[5] The first aspect of the present invention, wherein the substrate contains a filler material.

5. The magnetic recording medium substrate according to any one of items 4 above.

[6] The filler material according to claim 5, wherein the filler material has a particulate shape, and an average particle diameter Df thereof is 0.001 [μm] to: L0 [m]. A substrate for magnetic recording media.

[7] The filler material has a particulate shape, and the thickness Tc of the coating layer and the average particle diameter Df of the filler material are:

Tc / Df> 2

The magnetic recording medium substrate according to claim 5, wherein the following relationship is satisfied:

[8] The filler material has a cylindrical or fibrous shape, and an average diameter Df is 0.001.

2

6. The magnetic recording medium substrate according to claim 5, wherein the average length Lf is from 0.002 [m] to 1000 [m] from [m] to 50 [m].

[9] The filler material has a columnar or fibrous shape, and an average diameter Df thereof and the flat material.

2 Average length Lf is

Lf / Df> 2

2

[10] The thickness Tc of the coating layer and the diameter Df of the filler material are:

2

Tc / Df2> 2 The magnetic recording medium substrate according to claim 8 or 9, wherein the following relationship is satisfied.

[11] The thickness of the coating layer Tc is 0.001 [m] to 50 [m]. substrate.

[12] The volume force of the filler material occupying the entire substrate is 0.1 [%] to 50 [%]. The method according to any one of claims 5 to 11, A substrate for magnetic recording media.

[13] The force according to any one of claims 5 to 12, wherein a surface occupancy ratio of the filler material is 0.1 [%] to 50 [%] on the surface of the substrate. Substrate for magnetic recording media.

[14] The first aspect of the present invention is characterized in that a groove is formed on the surface of the substrate.

4. The magnetic recording medium substrate according to any one of 3).

[15] The groove has a configuration of one or more pattern forces selected from concentric, radial, grid, dot, or polygonal patterns. 15. A substrate for a magnetic recording medium according to item 14.

16. The magnetic recording according to claim 15, wherein the pattern is configured by a continuous groove, a discontinuous groove, or a combination of a continuous groove and a discontinuous groove. Media substrate.

[17] The magnetic recording medium substrate according to any one of [14] to [16], wherein a depth Dv of the groove is 0.001 [m] to l [m]. .

[18] The magnetic recording medium substrate according to any one of [14] to [17], wherein a width Wv of the groove is 0.001 [μm] to 10 [m]. .

[19] The groove depth Dv and the groove width Wv are:

Wv> Dv / 5

The magnetic recording medium substrate as set forth in any one of claims 14 and 18, wherein the force satisfies the following relationship.

[20] The thickness Tc of the coating layer and the depth Dv of the groove are:

Tc / Dv> 2 The magnetic recording medium substrate according to any one of claims 14 to 19, wherein the force satisfies the following relationship.

[21] The surface roughness Ra of the substrate before the coating layer is formed is 1 [ηπ! The maximum valley height Rv is 5 to 5000 [nm], and the maximum peak height Rp is 3 [nm] to 3000 [nm]. Item 20. The magnetic recording medium substrate according to any one of Items 20

[22] The thickness Tc of the coating layer and the surface roughness Ra of the substrate before the coating layer is formed,

5 X surface roughness Ra <coating layer thickness Tc <1000 X surface roughness Ra

The magnetic recording medium substrate according to any one of claims 1 to 21, wherein the following relationship is satisfied.

[23] For a magnetic recording medium, comprising a film forming step of forming a coating layer in a region of 90% or more of the surface of the substrate with respect to a resin-made substrate having a disk shape A method for manufacturing a substrate.

[24] The method further comprises a polishing step of polishing the coating layer,

The thickness of the coating layer before polishing, the surface roughness Ra of the substrate before the coating layer is formed, and the thickness of polishing the coating layer,

24. Production of a substrate for a magnetic recording medium according to claim 23, wherein the relationship of 5 X surface roughness Ra <polished thickness <0.7 X thickness of coating layer before polishing is satisfied Method.

25. The method for manufacturing a substrate for a magnetic recording medium according to claim 24, wherein the surface roughness Ra of the substrate after polishing is made less than 0.1 [nm] by the polishing.

[26] A base material made of resin having a disk shape is used as a substrate, a covering layer is formed in a region of 90% or more of the entire surface of the substrate, and a magnetic layer is formed on at least one surface of the substrate. A magnetic recording medium characterized by the above.