JP2003272121A - Magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively provide a perpendicular magnetic recording medium on which high density recording can be performed. <P>SOLUTION: The magnetic recording medium is characterized in that a first magnetic layer constituted of a ferromagnetic metal alloy containing cobalt and a non-magnetic metal oxide and a second magnetic layer consisting of a rare earth-transition metal alloy are laminated in this order on at least one surface of a substrate. <P>COPYRIGHT: (C)2003,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention
For magnetic recording media such as kibble disks and hard disks
In particular, for perpendicular magnetic recording media capable of high-density magnetic recording.
Related. [0002] 2. Description of the Related Art In recent years, due to the spread of the Internet, etc.
Corresponding to the handling of capacity image information,
The computer is equipped with a large-capacity hard disk
However, this hard disk drive saves video information.
Needs are high, and there is a demand for higher capacity and lower prices.
Yes. Also, a large amount of information stored on this hard disk
Backup or use on other computers
In order to use it, various removable recording media are used.
It is said. Magnetic tape, flexible disk, etc.
A flexible magnetic recording medium is similar to a hard disk.
Recording and reading time is short, and information recording
Many features such as small equipment required for recording and reading
have. For this reason, magnetic tape, flexible devices
As a typical removable recording medium,
Used for computer backup and storage of large amounts of data
It has been. And a small number of magnetic tape, flexible
Magnetic recording medium that can store large amounts of data on a Sibble disc
Body, and further improvement in recording density is required.
ing. For this reason, it has excellent high density recording characteristics.
The perpendicular magnetic recording method that has been attracting attention
Various recording methods, magnetic heads, magnetic recording media have been proposed
Yes. However, the conventional CoCr alloy, CoCrP
Perpendicular magnetic recording medium with t alloy as magnetic layer, higher
In order to achieve the areal recording density, to reduce noise,
The film thickness must be 30nm or less.
In ultra-thin films, magnetization is lost by heat at room temperature.
The problem of so-called “thermal fluctuation” becomes prominent and
It has become a big problem. On the other hand, high perpendicular magnetic anisotropy
As a material resistant to thermal fluctuation, Co / Pd
Co-based multilayer films such as Co and Pt, and TbFeCo
Rare earth transition metal alloys are known, but such magnetic materials
In the material, the in-plane direction exchange coupling is strong, and the conventional CoCrPt
There was a problem that the noise was higher than that of the base alloy. this
Recently, in-plane exchange coupling and vertical
CoCrPt-based perpendicular magnetism as a method to control magnetic anisotropy
Gas recording film and Co based multilayer film and rare earth transition metal alloy recording
Medium for laminating films (hybrid medium or CGC medium)
Called the body). In such a hybrid medium, CoCrP is used.
The substrate temperature should be increased to 200 ° C or higher when depositing the t-based alloy.
Heat to form a Co-based multilayer film or a rare earth transition metal alloy on it.
When filming, the substrate temperature must be room temperature.
A cooling process is required between these two layers of film formation process, and productivity
There was a problem. In addition, a polymer substrate is used as a nonmagnetic support.
Use flexible media or polycarbonate substrate
If you are going to use it
At the plate temperature, these polymer substrates are deformed.
Therefore, a recording medium could not be produced. [0005] The present invention is directed to high density recording.
To provide low-cost perpendicular magnetic recording media
It is what. Removable magnetic recording media
Magnetic tape that can be used as a
It is an object to provide a magnetic recording medium useful for discs, etc.
To do. [0006] The object of the present invention is to provide a support.
Ferromagnetic gold containing cobalt on at least one side of
A first magnetic layer composed of a metal alloy and a nonmagnetic metal oxide;
A second magnetic layer made of a rare earth transition metal alloy is laminated in this order.
It is solved by a magnetic recording medium characterized by
The [0007] DETAILED DESCRIPTION OF THE INVENTION A magnetic recording medium of the present invention comprises a support.
Ferromagnetic gold containing cobalt on at least one side of
A first magnetic layer composed of a metal alloy and a nonmagnetic metal oxide;
A second magnetic layer made of a rare earth transition metal alloy is laminated in this order.
This is a magnetic recording medium. Cobalt
Consists of containing ferromagnetic metal alloy and non-magnetic metal oxide
The magnetic layer is sputtered even if the temperature of the support is room temperature.
Since it can be formed by the ring method, etc.
Continue to deposit a rare earth transition metal alloy on top
It is possible to omit the substrate cooling step required before. Ma
Polycarbonate or polyethylene naphtha as a support
When a polymer support such as a rate is used as a substrate,
Magnetic recording with excellent recording characteristics without substrate deformation due to heat
A medium can be manufactured. The present invention will be described below with reference to the drawings.
FIG. 1 is a sectional view showing an embodiment of the present invention.
The Magnetic recording medium 1 contains cobalt on support 2
Made of ferromagnetic metal alloy and non-magnetic metal oxide
Second magnetism composed of first magnetic layer 3A and rare earth transition metal alloy
The layer 3B is formed. Magnetic layer 3A and magnetic layer 3
On the magnetic layer 3 made of B, the magnetic layer is deteriorated due to oxidation or the like.
Prevents wear from contact with the head and sliding members
A protective layer 4 for protection is formed. Moreover, on the protective layer 4
For the purpose of improving running durability and corrosion resistance
Layer 5 is provided. In the above layer structure, the magnetic layer 3A and
Adjust the surface properties of the support 2 between the supports 2
In addition, the gas generated from the support 2 reaches the magnetic layer 3A and the like.
An undercoat layer may be provided on the support 2 to prevent
Yes. Further, a ferromagnetic metal formed on the magnetic layer 3A
For improving recording characteristics by controlling crystal orientation
May be provided between the undercoat layer and the magnetic layer 3A.
Therefore, the crystal orientation of the ferromagnetic metal is improved and is shown in FIG.
A product with better characteristics than that obtained is obtained. Magnetism
When the magnetic recording medium is a magnetic tape, the above structure is usually provided on one side.
Layered, open reel or cartridge
Can be used in any form of what is stored inside
The When the magnetic recording medium is a flexible disk,
Usually, the support layer is provided on both sides of the support,
For mounting on flexible disk drives
Engaging means are mounted. Magnetic recording medium is hard disk
The substrate is usually a surface-polished glass substrate.
Used. There is also a disc drive in the center.
Engaging means for wearing is attached. Even more simple
Improve perpendicular magnetic recording characteristics when using a magnetic head
Therefore, a backing layer is provided. Magnetic layer formed on the magnetic recording medium of the present invention
Cobalt-containing ferromagnetic metal alloys and non-magnetic metal acids
First magnetic layer composed of fluoride and rare earth transition metal alloy?
A conventional CoCrP
High recording density recording is possible in the same way as the t-type alloy thin film magnetic layer.
In addition, the thermal fluctuation can be greatly reduced. Also
Since the magnetic layer can be formed at a substrate temperature of room temperature,
Conventional CoCrPt alloy magnetic layer and rare earth transition metal
It is more productive than media that combine the two. further
Removable magnetic recording with support made of polymer substrate
The capacity of the recording medium can be increased. Containing this cobalt
Ferromagnetic gold consisting of ferromagnetic metal alloys and nonmagnetic metal oxides
The metal thin film has been proposed for hard disks, as disclosed in
No. 73880, JP-A-7-311929, etc.
Manufactured by a method similar to that described
Can be used. The magnetic layer in the magnetic recording medium of the present invention comprises:
A so-called magnetic axis with an easy axis perpendicular to the magnetic layer surface
This is a perpendicular magnetic recording film. The direction of this easy axis is the base
Depending on the layer material, crystal structure, magnetic film composition and deposition conditions.
Can be controlled. Ferromagnetic material containing cobalt in the present invention
First magnetic layer composed of metal alloy and nonmagnetic metal oxide
The fine ferromagnetic metal alloy crystals are uniformly dispersed
And if you can achieve high coercivity without heating the substrate
Besides, magnetic recording with low noise as a result of uniform dispersibility
A medium can be obtained. Also perpendicular magnetic anisotropy
Has a second magnetic layer made of a high rare earth transition metal
Therefore, the magnetic recording information recorded once is strong against thermal fluctuation.
It can be held for a long time. Contains cobalt
As ferromagnetic metal alloys, Co, Cr, Ni, F
Alloys with elements such as e, Pt, B, Si and Ta can be used
Co-Pt, Co-Cr, Co-Pt-Cr, C
o-Pt-Cr-Ta, Co-Pt-Cr-B, etc. are magnetic
This is preferable because the recording characteristics are good. For example, CoPtCr used for perpendicular recording
As a preferable elemental composition of the alloy, Co is 65 to 80.
Atomic%, Pt 5-20 atomic%, Cr 10-20 atom
A composition selected from the range of%. Also this
When adding non-magnetic elements such as B and Ta to
Add to replace Pt or Cr in the range of less than%
Just do it. The greater the Co content, the greater the magnetization.
This increases the playback output of the signal, but increases the noise at the same time.
The On the other hand, the content of nonmagnetic elements such as Cr and Pt is high.
However, since the coercive force increases, the signal
Although the playback output decreases, the noise decreases. But
Depending on the magnetic head used and the equipment used.
It is preferable to adjust the blending ratio of elements. In addition to the composition, the anisotropy of magnetization is
Can be adjusted by conditions such as argon pressure
However, it also depends on the type of the underlayer described later. Use an underlayer
If no amorphous material is used or if an amorphous material is used
The layer is easily oriented vertically, but Cr or its alloys, Ru
Or if the alloy is used, in-plane orientation may occur.
Yes, it is used as an in-plane magnetic recording medium. Nonmagnetic metal oxides include Si, Zr, T
Oxides such as a, B, Ti and Al can be used, but silicon
Those using the oxides have the best recording characteristics. Ferromagnetic metal alloy containing cobalt and non-magnetic
The mixing ratio of conductive metal oxide is ferromagnetic metal alloy: nonmagnetic metal
In the range of oxide = 95: 5 to 80:20 (metal atomic ratio)
Preferably in the range of 90:10 to 85:15
It is particularly preferred. In this range
Therefore, separation between magnetic particles becomes sufficient, and coercive force decreases.
And the amount of magnetization can be kept high, so a high signal
Output is obtained. Ferromagnetic metal alloys containing cobalt and non-magnetic
Thickness of the first magnetic layer made of a mixture of conductive metal oxides
Is preferably 10 nm to 60 nm, more preferably 2
It is in the range of 0 nm to 30 nm. Such thickness and grazing
Thus, a medium with low noise can be obtained. Ferromagnetic metal alloy containing cobalt and non-magnetic
As a method of forming the first magnetic layer made of conductive metal oxide
The vacuum deposition method such as vacuum evaporation or sputtering is used.
Can be used. Of these, sputtering methods are good quality thin films.
Since it can be formed easily, it is suitable for the present invention. The
The sputtering method includes DC sputtering and RF sputtering.
Any of the sputtering methods can be used. Magnetic tape
Or when trying to manufacture flexible disks,
Sputtering is performed continuously on a continuous film.
It is preferable to use a web sputtering apparatus. The
Argon is used as the gas used for the atmosphere during sputtering.
Other rare gases may be used. Also non
A small amount of acid to adjust the oxygen content of magnetic metal oxides
Elemental may be introduced. Strong containing cobalt by sputtering
Magnetic layer made of magnetic metal alloy and non-magnetic metal oxide
Ferromagnetic metal alloy target and non-magnetic metal
Using two types of oxide targets, these co-sputtering
It is also possible to use the
Magnetism in accordance with the composition ratio of conductive metal alloy and nonmagnetic metal oxide
Mixture of insoluble metal alloy and non-magnetic metal oxide
When using a target, the ferromagnetic metal alloy is uniformly dispersed.
A magnetic layer can be formed. This mixture
The target can be produced by a hot press method. Rare earth transition metal formed as the second magnetic layer
An alloy is an alloy containing a rare earth metal and a transition metal.
Yeah. Examples of rare earth transition metal alloys include terbium and gadolinium.
Selected from nium, neodymium, and dysprosium
At least one rare earth metal and a small amount of iron and cobalt
An alloy containing at least one transition metal is preferred.
Of these, terbium, iron, and cobalt are the main components.
Alloy, and dysprosium, iron, and edge
More preferred is an alloy containing as a main component.
Alloys containing as a main component Bium, Iron and Cobalt
Is particularly preferred. The magnetic properties of rare earth transition metal alloys are mainly rare earths.
It is determined by the composition ratio of the similar metal and the transition metal. For example
When terbium is contained as a rare earth metal,
Alloys with a content of 14 to 14 atomic percent are more preferred
Good. Terbium content in the range of 14-20 atom%
By making the perpendicular coercive force of the magnetic layer
1500 Oe to 6000 Oe suitable for air recording (≈120
˜480 kA / m). Ma
The saturation magnetization of the magnetic layer is 50 to 800 emu / cc.
(≈ 0.063 to 1.0 Wb / m²Are preferred 10
0 to 400 emu / cc (≈0.13 to 0.50 Wb /
m²Is more preferable. Laminated first magnetic layer and second magnetic layer
The coercive force of the recorded magnetic recording medium is 2000 Oe to 6000.
Oe (≈160 to 480 kA / m), saturation magnetization is 50
~ 800A ・ m ²/ Kg (≒ 0.063-1.0Wb /
m²) Is preferable. The rare earth transition metal alloy includes chromium and
It may further contain at least one of nickel.
Corrosion resistance is improved by containing chromium and nickel.
The Method for forming a second magnetic layer comprising a rare earth transition metal
As a vacuum deposition method such as vacuum deposition or sputtering
The law can be used. Of these, sputtering is a good quality thin film.
Since the film can be easily formed, it is suitable for the present invention.
The As a sputtering method, a DC sputtering method,
Any of the RF sputtering methods can be used. Magnetic
When manufacturing tapes or flexible disks
The sputtering method can be performed continuously on a continuous film.
It is preferable to use a web sputtering device to film
Yes. The gas used for the atmosphere during sputtering is Argo
However, other rare gases may be used.
Sputtering the second magnetic layer of rare earth transition metal alloy
In order to form, two types of tar, rare earth metal and transition metal
Use get and use these co-sputtering methods
Although it is possible, the rare earth transition metal alloy to be formed
Homogeneously mix rare earth metals and transition metals that match the composition ratio.
Rare earth transition metal alloy
A uniformly dispersed magnetic layer can be formed. When the magnetic recording medium is a magnetic tape,
And will be described below. Flexible support for magnetic tape
As for, a synthetic resin film is used. Specifically
Aromatic polyimide, aromatic polyamide, aromatic poly
Amidoimide, polyetherketone, polyethersulfur
Hong, polyetherimide, polysulfone, polypheny
Ren sulfide, polyethylene naphthalate, polyethylene
Terephthalate, polycarbonate, triacetate
Synthetic resin film made of cellulose, fluororesin, etc.
Is mentioned. Good in the present invention without heating the substrate
Excellent recording properties due to excellent recording characteristics
Polyethylene terephthalate or
Is particularly preferably polyethylene naphthalate. The thickness of the flexible polymer support is preferably
3-20 μm, more preferably 4 μm-12 μm
The If the thickness of the flexible polymer support is thinner than 3 μm,
The degree is insufficient, and cutting and edge breakage are likely to occur. one
On the other hand, when the thickness of the flexible polymer support is thicker than 20 μm,
Less magnetic tape can be wound per magnetic tape
And the volume recording density is lowered. High rigidity
Therefore, the contact with the magnetic head, that is, the followability is
Getting worse. The surface of the flexible polymer support is a magnetic head.
Yes, in order to record and read information in contact with
It is preferable to be as smooth as possible. Flexible polymer support
Unevenness on the surface of the body significantly reduces signal recording and playback characteristics.
The Specifically, when using an undercoat layer described later,
Surface roughness measured by an optical interference type surface roughness meter is the center plane average.
Roughness (SRa) is usually within 5 nm, preferably 2 nm
The protrusion height measured with a stylus type roughness meter is usually 1 μm
Is preferably within 0.1 μm. Also undercoat
If no layer is used, measure with an optical interference surface roughness meter.
The average surface roughness (SRa) is usually 3 nm.
Within 1 nm, preferably within 1 nm, measured with a stylus roughness meter
The protrusion height is usually within 0.1 μm, preferably 0.06.
Within μm. On the surface of the flexible polymer support, the planarity is improved.
It is preferable to provide an undercoat layer for the purpose of good and gas barrier properties.
Good. Since the magnetic layer is formed by sputtering,
The coating layer is preferably excellent in heat resistance.
Examples of the material include polyimide resin and polyamide imide.
Use resin, silicone resin, fluorine resin, etc.
Can do. Solvent-soluble polyimide resin, thermosetting polyimide
Mide resin and thermosetting silicone resin have high smoothing effect
Particularly preferred. The thickness of the undercoat layer is 0.1 μm to 3.
0 μm is preferable. As thermosetting silicone resin,
Sol gel using silicon compound with organic group as raw material
A silicone resin polymerized by the method is preferably used. this
Silicone resin is part of the bond of silicon dioxide with organic groups.
It has a structure substituted with
Excellent thermal properties and better flexibility than silicon dioxide film
On the polymer support made of flexible film.
Even if the oil film is formed, cracks and peeling hardly occur. Also,
Direct coating of monomer as raw material on flexible polymer support
And can be cured. Moreover, general organic solvents
Since the monomer can be dissolved in the agent and applied,
Good wraparound against unevenness and high smoothing effect. Further
In addition, the polycondensation reaction is used to add catalysts such as acids and chelating agents.
Cures in a short time because it proceeds from a relatively low temperature.
The resin film can be formed using a general-purpose coating apparatus
be able to. Thermosetting silicone resin blocks gas
Excellent in properties. For this reason, when forming the magnetic layer or underlayer
Generated from a flexible polymer support,
Gas shielding ability to shield gas that hinders crystallinity and orientation
High and particularly suitable. On the surface of the undercoat layer, a magnetic head or guide
Low real contact area between magnetic tape and sliding members such as poles
For the purpose of reducing and improving sliding characteristics
It is preferable to provide (texture). Also, a small bump
Handling of a flexible polymer support by providing a support
The property is also improved. As a method of forming a microprojection, a sphere
A method of applying silica particles, applying an emulsion
The method of forming organic protrusions can be used, but the primer
In order to ensure the heat resistance of the layer, spherical silica particles are applied.
It is preferable to form minute protrusions. The height of the minute protrusion is preferably 5 nm to 60 nm.
Further, 10 nm to 30 mm is more preferable. Microprojections
If the height is too high, the space between the recording / reproducing head and the magnetic recording medium
-Recording loss due to loss of signal
If the small protrusion is too low, the effect of improving the sliding characteristics is reduced.
The density of microprotrusions is preferably 0.1-100 / μm2.
1 to 10 / μm 2 is more preferable. Closeness of minute protrusion
If the degree is too small, the effect of improving the sliding characteristics will be small.
If the amount is too large, the number of aggregates increases and the number of high protrusions increases.
As a result, the recording / reproduction characteristics deteriorate. Also using a binder
Thus, the microprotrusions can be fixed to the surface of the support. by
Use a resin with sufficient heat resistance for the binder.
Preferably, the resin with heat resistance is a solvent soluble type
Polyimide resin, thermosetting polyimide resin, thermosetting type
It is particularly preferable to use a recon resin. An underlayer may be provided under the magnetic layer.
preferable. As the underlayer, Ti, Pt, Ru, Pd, etc.
Metals or alloys based on these metals, or
Amorphous materials such as C, nitriding Si, Al, Ti, etc.
Products, oxides, and the like. Such an underlayer
Improves the orientation and graininess of the magnetic layer
This improves recording characteristics. The thickness of the underlayer is 10
nm to 200 nm is preferable, and 20 nm to 100 nm is preferable.
Particularly preferred. A magnetic layer is formed in a column shape by the underlayer
Are particularly preferred. By forming a columnar shape
Stable structure of separation between ferromagnetic metals and high coercive force
High output and dispersion of ferromagnetic metal
Resulting in a low noise magnetic recording medium.
The Furthermore, between the underlayer and the flexible polymer support.
In order to improve the adhesion and structure of the underlayer, seed
A layer can be provided. For the seed layer, Ta, Ta-
Si, Ni-P, Ni-Al, etc. can be used
The When performing perpendicular magnetic recording with a single pole head
A soft magnetic layer between the magnetic layer and the flexible polymer support.
It is preferable that By providing a soft magnetic layer,
Electromagnetic conversion characteristics can be improved. As a soft magnetic material
Can use materials such as permalloy and sendust. That
The film thickness is preferably 30 to 200 nm. A protective layer is provided on the magnetic layer. Protective layer
Prevents corrosion of the metallic material contained in the magnetic layer,
Wear due to pseudo contact or contact sliding between the magnetic disk and magnetic tape
Is provided to improve running durability and corrosion resistance.
It is done. The protective layer includes silica, alumina, titania,
Oxides such as luconia, cobalt oxide, nickel oxide,
Nitride such as titanium nitride, silicon nitride, boron nitride, charcoal
Carbides such as silicon carbide, chromium carbide, boron carbide, graphs
Use materials such as carbon, amorphous carbon, etc.
be able to. The protective layer is the same as the magnetic head material.
Or a hard film with a higher hardness than that,
It is hard to cause sticking and its effect is stable and lasting.
It is preferable because of its excellent sliding durability. At the same time,
The one with a low level is better because it has excellent corrosion resistance.
Yes. Such a protective film is produced by a CVD method.
Hard carbon film called diamond-like carbon (DLC)
Can be mentioned. The protective layer consists of two or more types of thin films with different properties
It can be set as the structure which laminated | stacked. For example, on the surface side
Hard carbon protective film is provided to improve the sliding characteristics, and magnetic
Nitride such as silicon nitride to improve corrosion resistance on the layer side
By providing a protective film, corrosion resistance and durability are at a high level.
It is possible to achieve both. On the protective layer, running durability and corrosion resistance are provided.
In order to improve, a lubricating layer is provided. The lubrication layer has charcoal
Lubricating hydrofluoric lubricants, fluorine lubricants, extreme pressure additives, etc.
Agent is used. As hydrocarbon-based lubricants,
Acids, carboxylic acids such as oleic acid, butyric acid butyrate
Esters such as
Phosphate esters such as acids and monooctadecyl phosphate
, Stearyl alcohol, oleyl alcohol, etc.
Carboxylic acid amides such as lucols and stearic acid amides
And amines such as stearylamine. Fluorine-based lubricants include the above hydrocarbon-based lubricants.
Remove some or all of the alkyl groups on the lubricant
Lubricants substituted with ruthenium groups or perfluoropolyether groups
A lubricant may be mentioned. As perfluoropolyether group
Is perfluoromethylene oxide polymer, perfluoro
Ethylene oxide polymer, perfluoro-n-propylene
Oxide polymer (CF₂CF₂CF₂O)_n, Perfluo
Loisopropylene oxide polymer (CF (CF_ThreeCF₂
O)_n Or a copolymer thereof. Specifically
Perfluoromethylene having a hydroxyl group at the molecular weight end
-Perfluoroethylene copolymer (manufactured by Augmont,
Product name FOMBLIN Z-DOL). As an extreme pressure additive, trilauryl phosphate is used.
Phosphate esters such as trilauryl phosphite
Such as acid esters and trilauryl trithiophosphite
Ophosphite, thiophosphate, disulfide
And sulfur-based extreme pressure agents such as benzyl. The above lubricants may be used alone or in combination.
It is possible to use a solvent in which a lubricant is dissolved in an organic solvent.
Spin coating, wire bar coating, gravure
Apply to the surface of the protective layer by a coat method, dip coat method, etc.
Or it can be attached to the surface of the protective layer by vacuum evaporation.
Yes. As a coating amount of the lubricant, 1 to 30 mg / m²Prefer
2-20 mg / m²Is particularly preferred. In order to further improve the corrosion resistance, rust prevention
It is preferable to use an agent in combination. As rust inhibitor, benzo
Triazole, benzimidazole, purine, pyrimidi
Nitrogen-containing heterocycles such as
Derivatives introduced with side chains, benzothiazole, 2-mer
Captobenzothiazole, tetrazaindene ring compound,
Nitrogen and sulfur containing heterocycles such as thiouracil compounds
And derivatives thereof. These rust inhibitors are lubricated
It may be mixed with the agent and applied on the protective layer, or the lubricant applied
Apply on top of the protective layer and then apply lubricant on it.
Also good. As an application quantity of a rust preventive agent, 0.1-10 mg /
m²Is preferably 0.5 to 5 mg / m²Is particularly preferred. Surface of the flexible polymer support on which the magnetic layer is formed
It is preferable to provide a backcoat layer on the opposite side.
That's right. Backcoat layer slides between magnetic recording medium and sliding member
Lubrication effect to prevent wear on the back of the magnetic recording medium
have. Also used as a lubricating layer for the backcoat layer
Backcoat by adding lubricants and rust inhibitors
Since lubricant and rust preventive agent are supplied from the layer side to the magnetic layer side,
It becomes possible to maintain the corrosion resistance of the magnetic layer for a long time. Ma
In addition, the magnetic layer can be adjusted by adjusting the pH of the backcoat layer itself.
The corrosion resistance of can be further increased. Back coat layer
Is non-carbon black, calcium carbonate, alumina, etc.
Magnetic powder and resin bonds such as polyvinyl chloride and polyurethane
Mixtures, and solutions in which lubricants and curing agents are dispersed in organic solvents
Apply by gravure method or wire bar method and dry
Can be produced. Add a rust inhibitor or lubricant to the backcoat layer
As a method of providing, it may be dissolved in the above solution
Then, it may be applied to the produced back coat layer. Next, the magnetic recording medium is a flexible disk.
The case where it is Flexible disc
The support of the magnetic head is composed of a magnetic head and a flexible disk.
In order to avoid impact when touching
Composed of synthetic resin film, that is, flexible polymer support
It is. Such synthetic resin films include aromatic
Aromatic polyimide, aromatic polyamide, aromatic polyamide
Polyimide, polyetherketone, polyethersulfone, poly
Reetherimide, polysulfone, polyphenylenesulfur
Fido, polyethylene naphthalate, polyethylene tele
Phthalate, polycarbonate, triacetate cellulose
Synthetic resin film made of glass, fluorine resin, etc.
It is. In the present invention, good recording characteristics can be obtained without heating the substrate.
A substrate having a good surface property.
Polyethylene terephthalate that is available and easily available
Or polyethylene naphthalate is particularly preferred. In addition, a synthetic resin is used as a flexible polymer support.
A laminate of a plurality of films may be used. Multiple
Flexibility by using laminated films with laminated sheets
Reduces warpage and undulation caused by the polymer support itself
You can. As a result, the surface of the magnetic recording medium is
Can significantly improve the scratch resistance of the magnetic layer
Yes. As a method of laminating a flexible film, a heat low
Roll laminating with steel plate, flat plate laminating with flat plate hot press, contact
Dry lamination, pre-lamination by applying adhesive to the contact surface
Laminating method using adhesive sheet molded into a sheet
Is mentioned. When using an adhesive for lamination, hot
Melt adhesive, thermosetting adhesive, UV curable adhesive, E
Uses B-curing adhesive, adhesive sheet, anaerobic adhesive, etc.
I can do it. The thickness of the flexible polymer support is 10 μm to
200 μm, preferably 20 μm to 150 μm,
Preferably they are 30 micrometers-100 micrometers. Flexible polymer
If the thickness of the support is less than 10 μm, stability during high-speed rotation
Sexuality decreases and surface blur increases. On the other hand, flexible polymer support
If the thickness of the holder is greater than 200 μm, the rigidity during rotation is high.
It becomes difficult to avoid the impact at the time of contact and magnetic
Invite the head to jump. The waist strength of the flexible support is expressed by the following equation.
The value at b = 10 mm is 0.5 kgf / mm²~ 2.
0kgf / mm²(≈4.9 to 19.6 MPa) range
It is preferable to be at 0.7 kgf / mm²~ 1.5
kgf / mm²(≈ 6.9 to 14.7 MPa) is more preferable
Good. Waist strength of support = Ebd^Three/ 12 In addition, this
Where E is the Young's modulus, b is the film width, and d is the film width.
Represents each lum thickness. The surface of the flexible polymer support is a magnetic head.
Be as smooth as possible to make a recording with
preferable. Unevenness on the surface of the support improves the signal recording / reproduction characteristics.
Reduce significantly. Specifically, the undercoat layer described later is used.
In the case of use, the surface measured with an optical interference type surface roughness meter
Roughness is 5 nm or less, preferably center surface average roughness SRa
Within 2 nm, the protrusion height measured with a stylus roughness meter is 1 μm
Is preferably within 0.1 μm. Also undercoat
If no film is used, measure with an optical interference type surface roughness meter.
The surface roughness is preferably within 3 nm in terms of the center plane average roughness SRa.
Or within 1nm, the protrusion height measured with a stylus roughness meter
It is within 0.1 μm, preferably within 0.06 μm. On the surface of the flexible polymer support, the planarity is improved.
An undercoat layer may be provided to improve good and gas barrier properties
preferable. In order to form the magnetic layer by sputtering or the like,
The undercoat layer preferably has excellent heat resistance.
Examples of the material include polyimide resin and polyamide resin.
Use polyimide resin, silicone resin, fluorine resin, etc.
You can. Thermosetting polyimide resin, thermosetting silicone
The resin is particularly preferred because of its high smoothing effect. undercoat
The thickness of the layer is preferably 0.1 μm to 3.0 μm. support
When laminating other resin films on the body, before laminating
An undercoat layer may be formed on the undercoat layer after lamination processing.
It may be formed. As the thermosetting polyimide resin, bisua
Like rilnadiimide (BANI made by Maruzen Petrochemical Co., Ltd.)
And imidomono having two or more terminal unsaturated groups in the molecule.
A polyimide resin obtained by thermal polymerization of
I can. This imide monomer is supported in the monomer state.
After application to the surface of the holder, heat polymerization can be performed at a relatively low temperature.
The raw material monomer can be directly applied to the support.
It can be applied and cured. This imido model
Nomers can be used by dissolving them in common organic solvents.
High productivity and workability and low molecular weight
Because of its low solution viscosity,
Good wraparound and high smoothing effect. The thermosetting silicone resin includes an organic group.
Using a silicon compound introduced with
A combined silicone resin is preferably used. This silico
In the resin, part of the silicon dioxide bond is replaced with organic groups.
Made of a structure that is significantly more heat resistant than silicone rubber
Excellent and more flexible than silicon dioxide film
Therefore, a resin film is formed on a support made of a flexible film.
However, cracks and peeling are unlikely to occur. In addition, the raw material
The nomer is applied directly on the flexible polymer support and cured.
General-purpose solvents can be used,
Good wraparound against unevenness and high smoothing effect. Further
In addition, the polycondensation reaction is used to add catalysts such as acids and chelating agents.
Cures in a short time because it proceeds from a relatively low temperature.
The resin film can be formed using a general-purpose coating apparatus
be able to. Thermosetting silicone resin blocks gas
Excellent flexibility and flexible polymer support when forming magnetic layer
Which can prevent crystallinity and orientation of the magnetic layer or underlayer
High gas shielding property to shield the gas to be used, especially suitable
The On the surface of the undercoat layer, a magnetic head and a flexible
Reduces the true contact area with the Sibble disc and improves sliding characteristics
For the purpose of improving, microprojections (textures)
It is preferable to provide it. Also, to provide microprojections
Further, the handleability of the flexible polymer support is improved.
As a method of forming microprojections, spherical silica particles are applied.
How to cloth, apply emulsion and shape organic protrusions
However, the heat resistance of the undercoat layer is ensured.
In order to maintain, fine silica particles are formed by applying spherical silica particles
It is preferable to do this. The height of the fine protrusion is preferably 5 nm to 60 nm.
Further, 10 nm to 30 mm is more preferable. Microprojections
If the height is too high, the spacing between the recording / reproducing head and the medium
Loss causes signal recording / reproduction characteristics to deteriorate, and microprotrusions
If it is too low, the effect of improving the sliding characteristics is reduced. Microprotrusions
The density of 0.1-100 pieces / μm²Is preferred, 1-1
0 / μm²Is more preferable. The density of microprojections is low
If it is too tight, the effect of improving the sliding characteristics is reduced and too much
Recording and playback with increased protrusions due to increased aggregated particles
Characteristics deteriorate. Also, using a binder,
It can also be fixed on the surface of the support. In the binder,
It is preferable to use a resin with sufficient heat resistance,
As resin with heat resistance, solvent-soluble polyimide resin
Grease, thermosetting polyimide resin, thermosetting silicone resin
It is particularly preferred to use it. An underlayer may be provided under the magnetic layer.
preferable. As the underlayer, Ti, Pt, Ru, Pd, etc.
Metals or alloys based on these metals, or
Amorphous materials such as C, nitriding Si, Al, Ti, etc.
Products, oxides, and the like. Such an underlayer
Improves the orientation and graininess of the magnetic layer
This improves recording characteristics. The thickness of the underlayer is 10
nm to 200 nm is preferable, and 20 nm to 100 nm is preferable.
Particularly preferred. A magnetic layer is formed in a column shape by the underlayer
Are particularly preferred. By forming a columnar shape
Stable structure of separation between ferromagnetic metals and high coercive force
High output and dispersion of ferromagnetic metal
Resulting in a low noise magnetic recording medium.
The Further, between the underlayer and the flexible polymer support.
In order to improve the adhesion and structure of the underlayer, seed
A layer can be provided. For the seed layer, Ta, Ta-
Si, Ni-P, Ni-Al, etc. can be used
The When performing perpendicular magnetic recording with a single pole head
A soft magnetic layer between the magnetic layer and the flexible polymer support.
It is preferable that By providing a soft magnetic layer,
Electromagnetic conversion characteristics can be improved. As a soft magnetic material
Can use materials such as permalloy and sendust. That
The film thickness is preferably 30 to 200 nm.
  It is preferable to provide an underlayer below the magnetic layer.
As the underlayer, Cr or Cr and Ti, Si, W, T
an alloy with a metal selected from a, Zr, Mo, Nb, etc., R
u, C and the like. A protective layer is provided on the surface of the magnetic layer. Protection
The protective layer prevents corrosion of the metal material contained in the magnetic layer,
For pseudo contact or contact sliding between magnetic head and magnetic disk
To prevent running wear and improve running durability and corrosion resistance
Provided. For the protective layer, silica, alumina, titanium
Such as near, zirconia, cobalt oxide, nickel oxide
Nitrogen such as oxide, titanium nitride, silicon nitride, boron nitride
Carbonization of chemicals, silicon carbide, chromium carbide, boron carbide, etc.
Materials such as carbon, graphite, and amorphous carbon
Can be used. The protective layer is equivalent to the magnetic head material.
Or a hard film with a higher hardness than that,
It is hard to cause sticking and its effect is stable and lasting.
It is preferable because of its excellent sliding durability. At the same time,
The one with a low level is better because it has excellent corrosion resistance.
Yes. Such a protective film is produced by a CVD method.
Hard carbon film called diamond-like carbon (DLC)
Can be mentioned. The protective layer consists of two or more types of thin films with different properties
It can be set as the structure which laminated | stacked. For example, on the surface side
Hard carbon protective film is provided to improve the sliding characteristics, and magnetic
Nitride such as silicon nitride to improve corrosion resistance on the layer side
By providing a protective film, corrosion resistance and durability are at a high level.
It is possible to achieve both. On the protective layer, running durability and corrosion resistance are provided.
In order to improve, a lubricating layer is provided. The lubrication layer has charcoal
Lubricating lubricants such as hydrogen fluoride lubricants, fluorine lubricants and extreme pressure additives
Agent is used. As hydrocarbon-based lubricants,
Acids, carboxylic acids such as oleic acid, butyric acid butyrate
Esters such as ruthenium, sulfos such as octadecyl sulfonic acid
Phosphate esters such as acids and monooctadecyl phosphate
, Stearyl alcohol, oleyl alcohol, etc.
Carboxylic acid amides such as lucols and stearic acid amides
And amines such as stearylamine. Fluorine-based lubricants include the above hydrocarbon-based lubricants.
Remove some or all of the alkyl groups on the lubricant
Lubricants substituted with ruthenium groups or perfluoropolyether groups
A lubricant may be mentioned. As perfluoropolyether group
Perfluoromethylene oxide polymer, perfluoro
Loethylene oxide polymer, perfluoro-n-propy
Ren oxide polymer (CF₂CF₂CF₂O)_n, Full
Oroisopropylene oxide polymer (CF (CF_Three) C
F₂O)_nOr a copolymer thereof. Specifically
Perfluoromethylene having a hydroxyl group at the molecular weight end
-Perfluoroethylene copolymer (manufactured by Augmont,
(Product name: FOMBLIN Z-DOL). As an extreme pressure additive, trilauryl phosphate is used.
Phosphate esters such as trilauryl phosphite
Such as acid esters and trilauryl trithiophosphite
Ophosphite, thiophosphate, disulfide
And sulfur-based extreme pressure agents such as benzyl. The above lubricants may be used alone or in combination.
It is possible to use a solvent in which a lubricant is dissolved in an organic solvent.
Spin coating, wire bar coating, gravure
Apply to the surface of the protective layer by a coat method, dip coat method, etc.
Or it can be attached to the surface of the protective layer by vacuum evaporation.
Yes. As a coating amount of the lubricant, 1 to 30 mg / m²Prefer
2-20 mg / m²Is particularly preferred. In order to further improve the corrosion resistance, rust prevention
It is preferable to use an agent in combination. As rust inhibitor, benzo
Triazole, benzimidazole, purine, pyrimidi
Nitrogen-containing heterocycles such as
Derivatives introduced with side chains, benzothiazole, 2-mer
Captobenzothiazole, tetrazaindene ring compound,
Nitrogen and sulfur containing heterocycles such as thiouracil compounds
And derivatives thereof. These rust inhibitors are lubricated
It may be mixed with the agent and applied on the protective layer, or the lubricant applied
Apply on the protective layer 18 before applying a lubricant.
May be. The coating amount of the rust inhibitor is 0.1 to 10 m.
g / m²Is preferably 0.5 to 5 mg / m²Is particularly preferred
Yes. When making a hard disk, support
Al or its alloy, glass, carbon, poly as body
Use carbonate, amorphous polyolefin, etc.
Yes. These materials are stamped, molded, etc.
Prepare a pre-processed shape, and use this table.
The surface was polished mechanically or chemically to make it sufficiently smooth
After that, provide a texture if necessary, moderate surface roughness
Finish. In addition, when making a hard disk
The technology described on the tape or flexible disk
Can be applied. The following is a description of magnetism using a flexible polymer support.
A method for manufacturing the recording medium will be described. Using film deposition equipment
A method for forming a magnetic layer on a flexible polymer support
The The film forming apparatus has a vacuum chamber and winds from a winding roll
The flexible polymer support made by the tension adjusting roll
The tension is adjusted and sent to the film formation chamber. The deposition chamber is
Argon in a state where the pressure is reduced to a predetermined degree by a pump.
Is supplied from the sputtering gas supply pipe at a predetermined flow rate.
ing. A flexible polymer support is provided in a film formation chamber provided in the film formation chamber.
Underlayer sputtering while being wound around
Atoms for underlayer formation jump from the target of the ring device
Then, a film is formed on the flexible polymer support. Next, in the film forming roll, the magnetic layer spa
Ferromagnetic metal alloys and non-magnetic metals attached to the tattering device
For forming a magnetic layer from a target in which oxides are uniformly dispersed
Atoms are released and a magnetic layer is formed on the underlayer. Next
Next, the surface on which the magnetic layer is formed is wound around the second film forming roll.
In the state of moving while
Atoms for underlayer formation jump out of the target and are flexible
The side opposite to the surface where the magnetic layer is formed on the tip of the polymer support is
A film is formed. Furthermore, on the film forming roll, the magnetic layer spa
Ferromagnetic metal alloys and non-magnetic metals attached to the tattering device
For forming a magnetic layer from a target in which oxides are uniformly dispersed
Atoms are released and a magnetic layer is formed on the underlayer. The flexible polymer support is obtained by the above process.
Magnetic layers are formed on both sides of the
It is wound up. In the above description, the flexible polymer support
Explained how to form magnetic layers on both sides of the holder
However, it is possible to form it on only one side in the same way.
is there. After forming the magnetic layer, diamond on the magnetic layer
Protective layer including carbon is formed by CVD method
It is. Utilizing high-frequency plasma applicable to the present invention
An example of the CVD apparatus will be described. Possible to form a magnetic layer
The flexible polymer support is unwound from a roll and
The bias voltage is supplied from the bias power source to the magnetic layer by the
It travels while being energized and wound around a film forming roll. one
Raw material gas containing hydrocarbon, nitrogen, noble gas, etc.
Plas generated by voltage applied from a high-frequency power supply
Nitrogen, noble gas on the metal thin film on the film forming roll
Is formed and wound on a take-up roll.
Be taken away. In addition, the surface of the magnetic film must be
Purified by glow treatment with rare gas or hydrogen gas
To ensure greater adhesion
The In addition, a silicon intermediate layer or the like is formed on the surface of the magnetic layer.
The adhesion can be further increased. [0065] The following examples and comparative examples illustrate the present invention.
To do. (Production of magnetic tape) Example 1-1 Polyethylene with a thickness of 6.3 μm and a surface roughness Ra = 1.2 nm
3-Glycidoxypro on terephthalate film
Pyrtrimethoxysilane, phenyltriethoxysila
, Hydrochloric acid, aluminum acetylacetonate, etano
The undercoat liquid consisting of
After drying and curing at 100 ° C., a 0.2 μm thick sheet
An undercoat layer made of ricone resin was prepared. Obtained under
Silica sol having a particle diameter of 25 nm on the coating layer and the undercoat liquid
Apply the mixed coating solution by gravure coating,
10 projections / μm with a height of 15 nm on the layer²At a density of
This was formed into a raw material for magnetic tape. Next, obtained in a web sputtering apparatus
A film is closely attached on a film-forming roll that is mounted with a raw fabric and cooled with water.
DC magnetron spa on the undercoat layer
An underlayer made of Ti with a thickness of 30 nm by the sputtering method
Formed, followed by a CoPtCr alloy (Co: Pt: C
r = 70: 20: 10 atomic ratio): SiO₂= 88: 12
The first magnetic layer having a composition of (metal atomic ratio) is 20 nm
Thickness is formed, and Tb₁₈Fe₇₂Co_Ten(Atomic ratio) or
A second magnetic layer having a composition of 5 nm was formed with a thickness of 5 nm. Next, the web on which the magnetic layer is formed is referred to as web-type C.
Attached to VD equipment, ethylene gas, nitrogen gas, argon
RF plasma CVD method using N gas as reaction gas
Nitrogen consisting of C: H: N = 62: 29: 7 (mol ratio)
Added diamond-like carbon (DLC) protective film of 10 nm
It was formed with a thickness. At this time, the magnetic layer has −400V.
A bias voltage was applied. Next, a magnetic layer of a flexible polymer support is formed.
Carbon black, calcium carbonate on the opposite side
, Stearic acid, nitrocellulose, polyurethane,
Dissolve isocyanate curing agent in methyl ethyl ketone.
Apply the scattered back coat solution by wire bar method.
Dry at 0 ° C to make a backcoat layer with a thickness of 0.5 µm.
Made. Furthermore, the surface of the protective layer has a hydroxyl group at the molecular end.
Perfluoropolyether lubricant (Augmont)
FOMBLIN Z-DOL) manufactured by KK
Tomo 3M HFE-7200)
Apply a gravure coating method to form a 1 nm thick lubricating layer
did. Next, after cutting the obtained raw material into a width of 8 mm
For 8mm video cassette after polishing the surface with tape
A magnetic tape was prepared by incorporating it into the cartridge. Comparative Example 1-1 In Example 1-1, the composition of the magnetic layer was changed to the first magnetic layer and the first magnetic layer.
Both of the two magnetic layers are Co: Pt: Cr = 70: 20: 10 (original
The ratio is less than the total thickness of 25 nm.
A magnetic tape was prepared as in 1. Comparative Example 1-2 In Example 1-1, the first magnetic layer was made of Co: Pt: Cr =
70:20:10 (atomic ratio), underlayer and first magnetic layer
The film is formed at a film forming roll temperature of 150 ° C.
Once wound up, the substrate is cooled with water to form the second magnetic layer.
A magnetic tape was prepared in the same manner as in Example 1-1 except that
It was. Comparative Example 1-3 In Example 1-1, the film thickness of the first magnetic layer was 25 nm.
And Example 1-1 except that the second magnetic layer was not formed.
Similarly, a magnetic tape was produced. The obtained magnetic tapes are shown below.
The characteristics are evaluated by Evaluation Method 1, and the results are shown in Table 1.
Shown in (Evaluation Method 1) 1. Magnetic properties The vertical coercive force Hc is measured with a sample vibration magnetometer (VSM).
The magnetic properties were measured. 2. Cupping amount Cut the magnetic tape to a length of 100 mm and make it smooth.
Place the tape on the lath plate and measure the tape width.
The deformation in the width direction was evaluated as the cupping amount. 3. C / N Recording with inductive head, playback track width 2.2
Using an MR head with μm and reproduction gap of 0.26 μm
Recording and playback with a linear recording density of 130 kFCI
The signal / noise (C / N) ratio was measured. At this time,
The tape / head relative speed is 10m / sec.
The weight was 29.4 mN (3 gf). 4). durability Still playback with 8mm video tape recorder and output
Still playback time until the initial value becomes -3 dB
Was expressed as endurance time. The measurement environment is 10% at 23 ° C.
RH was used and the test was performed for a maximum of 24 hours. 5). Preservability Store in an environment of 60 ° C and 50% RH for 72 hours.
The decrease in signal output was examined. [0076] [Table 1] From the above results, the magnetic tape of the present invention has the recording characteristics.
It can be seen that it is excellent in durability, durability and storage. on the other hand,
Comparative Example 1 in which the magnetic layer does not contain a nonmagnetic metal oxide
1 has a reduced coercive force (Hc) and recording characteristics
It is falling. In addition, increase the deposition temperature of the underlayer and magnetic layer
In Comparative Example 2, the coercive force was improved, but the flexibility was high.
The molecular support film is deformed by heat, making it extremely durable.
It got worse. The surface of the tape was observed with a microscope.
The fine cracks were generated in the magnetic layer. Rare earth
Preserved in the sample of Comparative Example 1-3 in which no transfer metal was used
Later signal output was large, and the effect of thermal fluctuation appeared. (Flexible disk / Hard disk
Production) Example 2-1 Polyethylene having a thickness of 63 μm and a surface roughness Ra = 1.4 nm
3-Glycidoxypropyl on nnaphthalate film
Trimethoxysilane, phenyltriethoxysilane, salt
Acid, aluminum acetylacetonate, ethanol
After applying the undercoating liquid consisting of
Dry and harden at 0 ° C, 1.0μm thick silicon tree
An undercoat layer made of fat was prepared. Particles on this subbing layer
Coating in which silica sol with a diameter of 25 nm is mixed with the undercoat liquid
Apply the liquid by gravure coating method, height 1 on the undercoat layer
5 nm protrusions were formed at a density of 10 pieces / μm 2. Ma
The undercoat layer is formed on both sides of the flexible polymer support film.
Formed. Using the obtained flexible polymer support film as a raw material
On the contrary, it was mounted on a sputtering apparatus. Next, obtained in a web sputtering apparatus
A film is closely attached on a film-forming roll that is mounted with a raw fabric and cooled with water.
DC magnetron spa on the undercoat layer
An underlayer made of Ti with a thickness of 30 nm by the sputtering method
Formed, followed by a CoPtCr alloy (Co: Pt: C
r = 70: 20: 10 atomic ratio): SiO₂= 88: 12
The first magnetic layer having a composition of (metal atomic ratio) is 20 nm
It is formed with a thickness, and Tb18Fe72Co10 (atom
A second magnetic layer having a composition of
It was. The underlayer and magnetic layer were formed on both sides of the film.
Next, the web with a magnetic layer is installed in a web-type CVD apparatus.
Put ethylene, nitrogen gas, argon as reaction gas
C: H: N = 62: 2 in the RF plasma CVD method used
Nitrogen-added diamond-like charcoal consisting of 9: 7 (mol ratio)
A protective film made of element was formed to a thickness of 10 nm. Naoko
At that time, a bias voltage of −400 V is applied to the magnetic layer.
It was. A protective layer was also formed on both sides of the film. Next, a hydroxyl group is attached to the surface of the protective layer on both sides.
-Based perfluoropolyether lubricant (Monte
Fluoros FOBBLIN Z-DOL)
Dissolved in solvent (HFE-7200 manufactured by Sumitomo 3M)
The solution was applied by gravure coating and lubricated with a thickness of 1 nm.
A layer was formed. A magnetic device with a diameter of 94 mm is obtained from the obtained raw fabric.
After punching into a disk shape and tape polishing,
Synthetic resin cartridge for Kisible Disc (Fuji Photo
Incorporated into Film 100 Zip100)
A bull disc was produced. Example 2-2 The diameter 65 mirror-polished as the substrate in Example 2-1
Use a glass substrate of mm and batch type
Using a putter device, a base having the same composition as in Example 2-1.
Layer and magnetic layer are formed on both sides.
Formed. Example by dip coating method on this sheet
The same lubricating layer as that of 2-1 was formed. Tape this
A hard disk was produced. Comparative Example 2-1 In Example 2-1, the composition of the magnetic layer was changed to the first magnetic layer and the first magnetic layer.
Both of the two magnetic layers are Co: Pt: Cr = 70: 20: 10 (original
The ratio is less than the total thickness of 25 nm.
In the same manner as in Example 1, a flexible disk was produced. Comparative Example 2-2 In Example 2-1, the first magnetic layer was made of Co: Pt: Cr =
70:20:10 (atomic ratio), underlayer and first magnetic layer
The film is formed at a film forming roll temperature of 150 ° C.
Once wound up, the substrate is cooled with water to form the second magnetic layer.
A flexible device was prepared in the same manner as in Example 2-1, except for the above.
A disc was prepared. Each sample obtained was evaluated as shown below.
The characteristics are evaluated by Method 2, and the results are shown in Table 2.
The (Evaluation method 2) 1. Magnetic properties The vertical coercive force Hc is measured with a sample vibration magnetometer (VSM).
The magnetic properties were measured. 2. Face shake 3000 flexible disks and hard disks
Rotate at rpm and at a radius of 25mm from the center
The surface displacement was measured with a laser displacement meter. 3. C / N Recording with inductive head, playback track width 2.2
Using an MR head with μm and reproduction gap of 0.26 μm
Recording and playback with a linear recording density of 130 kFCI
The signal / noise (C / N) ratio was measured. At this time
The number of rolls is 3000rpm and the head is 35mm in radius.
It was measured. Head weight is 29.4mN (3gf)
It was. 4). Modulation Reproduction output at the time of the C / N measurement for the entire disc
Measure the ratio of the minimum value of this output to the maximum value to 100
Expressed as a fraction. 5. durability Flexible disks except for hard disks
Sibble disk drive (Fuji Photo Film Zi
p100 drive) with repeated recording and playback
Run and run when the output reaches the initial value -3dB.
Stopped and set as the endurance time. The environment is 23 ° C 50% RH
The test was conducted for a maximum of 300 hours. 6). Preservability Store in an environment of 60 ° C and 50% RH for 72 hours.
The decrease in signal output was examined. [0085] [Table 2] As can be seen from the above results, the flexible
Sibble discs have excellent recording characteristics, durability, and storage stability.
I understand that Example using glass substrate as substrate
In 2-2, Example 2-1 which is a flexible disk
On the other hand, C / N is slightly lowered. This is a relative output
This is because the hard disk is harder.
Because the flying height of the head is higher than that of a rewritable disk
Conceivable. In addition, nonmagnetic metal oxide (Si
O₂In Comparative Example 2-1, which did not use
However, the recording characteristics are deteriorated. Furthermore, underlayer and magnetic layer
In Comparative Example 2-2 where the film formation temperature was increased, the coercive force was improved.
However, the flexible polymer support film is deformed by heat.
The surface blur and durability deteriorated. [0087] The present invention provides a removable magnetic recording medium and
Magnetic tape that can be used
This is a magnetic recording medium useful for disk etc.
Possible to provide low-cost perpendicular magnetic recording media
The

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an embodiment of the present invention;
It is sectional drawing cut | disconnected in the orthogonal | vertical direction with respect to the support surface. [Description of Symbols] 1: Magnetic recording medium, 2: Support, 3A: First magnetic layer, 3
B: second magnetic layer, 3: magnetic layer, 4: protective layer, 5: lubricating layer

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Claims (1)

What is claimed is: 1. A first magnetic layer comprising a ferromagnetic metal alloy containing cobalt and a nonmagnetic metal oxide and a rare earth transition metal alloy formed on at least one surface of a support. A magnetic recording medium, wherein two magnetic layers are laminated in this order.