JP2003036516A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium that is possible to record in high density with low error rate and advantageously used for a magnetic computer data recording/reproducing tape suitable for magnetic recording/ reproducing system. SOLUTION: This is a magnetic recording medium having magnetic layer containing ferromagnetic powder and binder on a base, and characterized in that it has projections on the surface with their heights distributed as motioned below: Projection distribution: area A where the number a of projections (20 nm high or higher but 30 nm or less) is 52.5 to 92.5% (A), area B where the number b of projections (30 nm high or higher but 40 nm or less) is 9 to 29% (B), and area C where the number c of projections (40 nm high or higher) is 0 to 18.5% (C). Further, 100×a/(a+b+c)=A, 100×b/(a+b+c)=B, and 100×c/(a+b+c)=C.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium.
In particular, a helicopter with a narrower data recording track width.
Suitable for Cull-scan type magnetic recording / reproducing system
Useful as magnetic tape for computer data recording
It relates to the coming magnetic recording medium. In recent years, minicomputers and personal computers have been developed.
Computer or workstation
As computer systems become more popular,
IWAYU, a magnetic tape for recording computer data
A backup tape is being used. backup
Tape improves computer information processing capabilities and processing speed
It has a large recording capacity by speeding up,
In addition, it has high running durability and is even easier to use.
In order to efficiently record and play back recording media,
The demand from the head is that there is little head wear and long life
There is a strong demand. Also, the backup tape is
Wide range of environmental conditions depending on the usage environment of the computer
(Especially in highly variable temperature and humidity conditions)
High reliability with no occurrence of errors during recording and playback
It is desirable to have it. Generally, magnetic tape is a synthetic tree.
A magnetic layer is provided on a nonmagnetic support that is a flexible material such as oil.
It is the structure which was made. Also achieve higher recording density
For this purpose, a nonmagnetic layer is provided on a nonmagnetic support, and
Magnetic tapes with a thin magnetic layer have also been proposed.
The For example, in Japanese Patent Laid-Open No. 5-182178
The non-magnetic layer and the magnetic layer having a thickness of 1.0 μm or less
Two-layer magnetic tape provided on a nonmagnetic support in sequence
Has been proposed. It has a thin magnetic layer as described above.
Two-layer magnetic tape is used for computer data recording.
There is a statement that it can be used even if the layer of the magnetic tape
As a constitution, the nonmagnetic support is 4 to 80 μm thick, the lower layer
Non-magnetic layer of 1.0 μm to 5.0 μm thick, and above
The magnetic layer is 0.05 μm to 0.6 μm (more preferably
Is preferably 0.05 to 0.3 μm)
It is described. Specifically, as an example, 7 μm
2 μm thick on m polyethylene terephthalate support
A nonmagnetic layer and a 0.2 μm thick magnetic layer are provided in this order.
Printed magnetic tape is described. Also, in this publication
Can use aromatic polyamide as a support material
There is also a description. The thin magnetic layer disclosed in the above publication is provided.
The two-layer magnetic tape is relatively thin overall
Although it is advantageous for high-density recording,
Still sufficient for use as a magnetic tape for data recording
The recording capacity cannot be achieved. On the other hand, magnetic layers and non-magnetic
The thickness structure of the magnetic layer is also suitable for running durability and contact with the magnetic head.
This will directly affect the condition of contact with the head. That
It is easy to influence the electromagnetic conversion characteristics such as result reproduction output.
The Therefore, the overall thickness is suppressed and these properties are reduced.
Suitable for computer data recording
Development of a group is desired. Especially for computer data
In order to ensure reliable data,
Magnetic recording media with lower
It becomes important. Also, hitting the magnetic head
However, if the magnetic recording medium itself is thin,
Large head wear due to good head contact
It often causes problems. Also on the tape end face
Edge damage (due to end face breakage and rubbing
Causing edge flaking and peeling of the magnetic layer). Magnetic
Helicopter using rotating magnetic head as a recording / reproducing system
Cull scan method is adopted, but higher recording density
In order to achieve this, the data recording track width has been
Data can be recorded / reproduced in a narrower track width.
A new magnetic recording system is also being developed. But,
When the overall thickness of the magnetic tape becomes very thin,
Ftrack (track deviation = deviating from normal track)
Therefore, faithful recording / playback becomes impossible and data cannot be read.
The phenomenon that it becomes easy to occur occurs. Accordingly, the first aspect of the present invention is as follows.
The purpose of this is to achieve a larger recording capacity and for data
Error rate to ensure reliable and reliable data
Low margin, higher margin and excellent running durability
Less deterioration in performance in electromagnetic conversion characteristics after storage
Magnetic data storage for computer data recording with stable performance
It is to realize a magnetic recording medium advantageous as a group.
The second object of the present invention is to rotate as a magnetic recording / reproducing system.
Corresponding to the helical scan method using a magnetic head,
Large recording capacity, running durability and electromagnetic conversion characteristics
In addition, the friction coefficient is small and the running resistance is low.
Reliable for edge wear, good head wear, reliable
Highly effective as a magnetic tape for computer data recording
It is to provide a magnetic recording medium that can be used advantageously. Further
In addition, the object of the present invention is that high-density recording is possible and magnetic recording / reproduction is possible.
Magnetic tape for computer data recording suitable for the system
By providing a magnetic recording medium advantageously used as
is there. The object of the present invention is to provide a support.
Magnetic recording having a magnetic layer comprising a ferromagnetic powder and a binder thereon
In the recording medium, protrusions with the following protrusion heights on the surface of the magnetic layer
A magnetic recording medium characterized by having a distribution
Achieved. Projections with projection heights in the projection distribution A region (20 nm or more and less than 30 nm)
Number a is 52.5 to 92.5% (A) Projection height with B region (30 nm or more and less than 40 nm)
Number b is 9 to 29% (B) The number c of protrusions at the height of protrusion in the C region (40 nm or more) is 0 to 0.
18.5% (C) where 100 × a / (a + b + c) = A, 100 × b
/ (A + b + c) = B, 100 × c / (a + b + c) =
C. The present invention also provides the following aspects (1) to (6).
It is preferable that (1) Mainly non-magnetic powder and binder between support and magnetic layer
Characterized in that a lower layer (nonmagnetic layer) is provided
Magnetic recording medium. (2) The support is an aromatic polyamide support or polyester.
Tylene naphthalate support having a thickness of 1.0
μm to 6.0 μm, more preferably 1.5 μm or less
The above-mentioned magnetic recording characterized by being 5.8 μm or less
Medium. (3) The total thickness of the magnetic recording medium is 7.0 μm or less.
The magnetic recording medium described above. (4) The thickness of the magnetic layer of the magnetic recording medium is 0.01 μm or more
The above magnetic recording, wherein the magnetic recording is 0.25 μm or less
Medium. (5) Track width (track pitch) is 7.0 μm or less
More preferably, the magnetic recording reproduction is in the range of 3 to 7 μm.
The above-mentioned magnetic tape for a raw system
Magnetic recording medium. (6) Be a magnetic tape for computer data recording
A magnetic recording medium as described above. (7) Recording and playback using the helical scan method
The magnetic recording medium as described above. The present invention will be described in more detail below. Main departure
Akira features a protrusion distribution with a specific protrusion height on the surface of the magnetic layer.
This makes it possible to provide optimal magnetic recording media.
It was. The protrusion distribution of the protrusion height is A region (20 nm to 30 nm
protrusion height of less than nm, B region (30 nm to 40 nm)
Less) and protrusion height of C region (40 nm or more)
Proportion of the number of protrusions per unit area (occupancy)
Rate), the number of A regions is a, B region
Where b is the number of C and the number of C regions is c, the protrusions in the A region
Number ratio A = 100 × a / (a + b + c) is 52.5
~ 92.5%, preferably 55.0-91.5%,
Preferably, 56.0 to 91.0% of the number of protrusions in the B region
Ratio B = 100 × b / (a + b + c) is 9 to 29%, good
Preferably it is 10.0-25.0%, and the percentage of the number of protrusions in the C region
Total C = 100 × c / (a + b + c) is 0 to 18.5%,
Preferably it is 0.00 to 17.0%. Up
The projection distribution of the projection height is measured with an atomic force microscope (AFM).
Is required. In the present invention, DIGITAL INST
AMF (AtomicForce) manufactured by RUMENT
Microscope) NANOSCOPE III
It was used. Measurement on the magnetic layer in contact mode
A range of 30 μm × 30 μm is scanned. Sca
The speed is 0.25 seconds / line or more. Each area above
The height of the protrusion at the point is from the reference plane below to the top of the protrusion.
It means the distance at. The reference plane is within the measurement area of the magnetic layer
This is the surface where the volume of the protrusion and the recess is equal. The measurement is
When sliced at a height of 19.5 nm from the reference plane
29.4 nm height from the reference plane
The number excluding the number of crossing protrusions when sliced with
The number of protrusions is a. Similarly, the height is 29.5n from the reference plane
When slicing at m, the reference plane is calculated from the number of protrusions
When crossed at a height of 39.4 nm
The number excluding the number of protrusions is defined as the number of protrusions b. Higher than the reference plane
Intersects with protrusions when sliced at 39.5 nm or more
Let the number be the number of protrusions c. The ratio based on the number of protrusions
Find A, B and C. Further, the protrusions other than the above-mentioned area, that is, the height is
The protrusion of less than 20 nm is the surface property of the magnetic layer of the magnetic recording medium.
From this point of view, there is no effect on the electromagnetic conversion characteristics. In the present invention, the protrusion having the protrusion height on the surface of the magnetic layer is provided.
By maintaining the distribution as above, the magnetic head
The contact area is efficiently optimized and the error rate is reduced.
Keeping it low and impairing electromagnetic conversion characteristics and running durability
No magnetic recording medium can be provided. Magnetic recording
The friction coefficient is reduced even if the layer thickness of the recording medium is reduced to 7.0 μm or less.
Small, low running resistance and little edge damage
Reliable computer data recording that is advantageous for head wear
A magnetic recording tape can be provided. A preferred embodiment of the present invention is an aromatic polyamid.
One support or polyethylene naphthalate support
On the other side, substantially non-magnetic containing non-magnetic powder and binder
The lower layer and the magnetic layer containing ferromagnetic powder and binder are in this order.
It has it. An optional back on the other side of the support.
It does not matter if it has a quart layer or servo signal.
A signal control magnetic layer may be provided. And magnetic recording medium
The total thickness is 7.0 μm or less, and the thickness of the magnetic layer is
It is preferable that it is 0.01 μm or more and 0.25 μm or less.
Yes. Aromatic polyamide support or polyethylene
Naphthalate support is supported arbitrarily according to its intended use
Corona discharge treatment can be performed on both sides of the body. Computer data recording magnetic tape
Backup tapes are becoming thinner and thinner with the increase in capacity in recent years.
In the direction. Demanded for backup tapes accompanying thinning
The required characteristic is high-density recording, achieving a large recording capacity
In addition, it is to ensure stable running durability.
Furthermore, the protrusion distribution of the protrusion height on the magnetic layer surface of the magnetic recording tape
Is maintained in the present invention to reduce the friction coefficient and
Reduces the rate of contact and reduces the contact area with the head
This reduces the amount of wear on the head.
Data recording magnetic tape with a balance between safety and running durability
It became possible to secure a loop. This is repeated
Damage to the tape edge surface during tape running
It is possible to reduce it and it is highly reliable in terms of running durability.
A magnetic tape for data recording could be realized. In addition, the magnetic recording medium of the present invention can provide a rotating magnet.
Tape-like magnetic recording with helical scanning method
Recording on the recording medium with a data track width of 7.0 μm or less
Magnetic recording method became possible. The inventor of the present invention is concerned with the layer structure of the magnetic recording medium.
Therefore, the thickness of the magnetic layer is made thinner than the conventional one.
As a result, the total thickness of the magnetic recording medium is 7.0 μm or less.
Despite being very thin and good per head,
The coefficient of friction is small and the error rate is kept low.
Less wear, more stable running durability and after storage
Even in electromagnetic conversion characteristics, etc., there is little degradation in performance and reliability
Highly effective as a magnetic tape for computer data recording
Found that magnetic recording media can be used
It was. The projection distribution of the projection height on the surface of the magnetic layer, ie,
There are various ways to change the number of surface protrusions and the height of surface protrusions
For example, calendar temperature, pressure, speed
Method of changing molding conditions such as magnetism in the treatment process before dispersion
Many organic solvents are used during the kneading process with the body and binder.
Those who use the amount to change the degree of strength from weakness to strength
By leaving a large amount of residual solvent in the magnetic layer during
Render conditions can be selected arbitrarily and the magnetic layer surface can be changed.
Methods, or methods of adding non-magnetic powder in a prescription
Conceivable. In the present invention, a small amount and the most reliable
The means to change the magnetic layer surface in a simple way is to the magnetic layer
Addition of carbon black. The number of surface protrusions and the height of surface protrusions of the present invention
To achieve this, it is preferable to use carbon black for the magnetic layer.
The preferred embodiment will be described in detail. Carbon black average
The particle diameter is preferably 10 to 300 nm, and 20 to 150 n.
m is more preferable. The amount of carbon black added is
Usually in the range of 0.01 to 30% by mass with respect to the ferromagnetic powder
And is preferably in the range of 0.05 to 20% by mass.
That's right. Carbon black used in the magnetic layer is for rubber
Furnace, rubber thermal, color black, ace
Tylene black or the like can be used. Specific surface area
Usually 5 to 500m ² / G, 8 to 250 m ² /
A range of g is preferred. DBP oil absorption is usually 10-40
It is in the range of 0ml / 100g, 30-380ml / 1
A range of 00 g is preferred. pH is 2-10, moisture content is
0.1 to 10%, tap density is 0.1 to 1.0 kg / l
(0.1 to 1.0 g / cc) is preferable. Carbon black used in the present invention
As a physical example, BLACKPEARL manufactured by Cabot Corporation
S 2000, 1300, 1000, 900, 800,
700, VULCAN XC-72, manufactured by Asahi Carbon Corporation
80, # 60, # 55, # 50, # 35, Mitsubishi Chemical Industries
# 2400B, # 2300, # 5, # 900, # 9
50, # 970, # 1000, # 30, # 40, # 10
B, CONDUCTEX S manufactured by Columbian Carbon
C, RAVEN 150, 50, 40, 15 etc.
It is done. Surface treatment of carbon black with a dispersant
Or part of the surface even if it is grafted with resin
You may use what made it graphite.
Also, before adding carbon black to the magnetic paint,
It may be dispersed with a first binder. These carbon
Black can be used alone or in combination
The Carbon black prevents the magnetic layer from being charged and has a low coefficient of friction.
There are also functions such as reduction, light shielding, and film strength improvement.
Depends on the carbon black used. Magnetism of the present invention
Carbon black that can be used in the layer is, for example, “Carbon
Refer to “Rack Handbook” (Carbon Black Association)
be able to. A non-magnetic flexible support used in the present invention;
Polyethylene terephthalate, polyethylene naphtha
Polyesters such as tarates, polyolefins, cells
Roast acetate, polycarbonate, polyamid
, Polyimide, polyamideimide, polysulfone, etc.
Polyethylene naphthalate can be used
Or aromatic polyamide is preferred. Used in the present invention
F-5 value of tape running direction of non-magnetic support is preferred
Or 5-50kg / mm ² (49-490 MPa), TE
-The F-5 value in the width direction is preferably 3-30 kg / mm
² (29.4 to 294 MPa) and the longitudinal direction of the tape
The F-5 value is generally higher than the F-5 value in the tape width direction.
Although it is necessary to increase the strength in the width direction,
This is not the case. The tape running direction and width direction of the support
The thermal shrinkage at 100 ° C for 30 minutes is preferably 3% or less
Lower, more preferably 1.5% or less, at 80 ° C. for 30 minutes
The thermal shrinkage is preferably 1% or less, more preferably 0.
5% or less. Breaking strength is 5-100kg in both directions
/ Mm ² (49-980 MPa), elastic modulus is 100-2
000kg / mm ² (0.98 to 19.6 GPa) is preferred
Good. The thickness of the support is preferably 1.0 μm to 6.0 μm.
Furthermore, it is preferable that it is 1.5 μm to 5.8 μm.
That's right. The support is a corona according to the purpose of the magnetic tape.
It can be used after being subjected to discharge treatment and slow current treatment. Concrete
In particular, a long aramid support and polyethylene naphth
Corona discharge treatment on both sides of the talate support (Toyo Pillar
(Used by Pillar Corona Treater, Inc.)
Electrodes are applied on the coated surface of the support, and dielectrics (a
A plate current with a high frequency transmitter on the electrode
(50 mA) is applied. Corona discharge treatment
This can be done on both sides of the support as described above.
come. Subsequently, ion wind is generated on the support after corona discharge treatment.
Apply to the device (manufactured by Shinko Co., Ltd.) and perform slow current treatment. The magnetic layer of the magnetic recording medium of the present invention has a ferromagnetic layer.
A powder is dispersed in a binder. Used
Ferromagnetic powder, ferromagnetic iron oxide, cobalt-containing ferromagnetic oxidation
Such as iron, barium ferrite powder or ferromagnetic metal powder.
The As the ferromagnetic metal powder, Fe, Ni, Fe-Co,
Fe-Ni, Co-Ni, Co-Ni-Fe, etc. alone or
Is an alloy, and within a range of 20% by mass or less of the metal component
In aluminum, silicon, sulfur, scandium, and titanium
, Vanadium, chromium, manganese, copper, zinc, it
Palladium, molybdenum, rhodium, palladium, gold, tin,
Antimony, boron, barium, tantalum, tungsten
, Rhenium, silver, lead, phosphorus, lanthanum, cerium, platinum
Including raceogyme, neodymium, tellurium, bismuth, etc.
be able to. The magnetic powder is, for example, disclosed in JP-A-8-2.
As described in Japanese Patent No. 55334, Co is Fe
10 to 40 atomic%, Al is 2 to 20 atomic%,
Sintering that Y is contained in 1 to 15 atomic%
It is preferable from the viewpoint that it is less and excellent in dispersibility. Ma
The ferromagnetic metal powder contains a small amount of water, hydroxide or oxide.
It may be included. Further, the magnetic recording medium of the present invention
The ferromagnetic powder used in the magnetic layer of Fe is mainly composed of Fe.
And the average major axis length is 0.05 to 0.19 μm, and
It is the magnetic powder that the crystallite size is 100 to 230 mm
It is preferable for reducing the noise while making the powder high
That's right. Furthermore, it is used for the magnetic layer of the magnetic recording medium of the present invention.
Ferromagnetic powder usually has a coercive force of 79 to 316 kA / m.
Yes, and σs is usually 90 to 170 A · m ² / Kg
There is less recording demagnetization loss and thermal fluctuation
This is preferable from the viewpoint of preventing the amount of magnetization from being reduced. More
In addition, the specific surface area of the ferromagnetic powder is 35-60 m. ² / G
The pH should be 7 or more.
It is preferable from the viewpoint of affinity with a slider. Hexagonal crystals
In the case of a ferrite-based ferromagnetic powder, a plate diameter of 40 nm or less is preferable.
More preferably, 10 to 35 nm is more preferable. Hc is needle-shaped
A range similar to gold powder is preferred. σs is 45 to 75 A ·
m ² / Kg, preferably 50-70A · m ² / Kg, plate
The ratio (plate diameter / thickness) is 2-15, preferably 3-8.
The Average particle volume is 2000-12000nm ^Three Like
Or 3000 ~ 10000nm ^Three It is. These strong magnets
The manufacturing method of the conductive powder is already known, and the ferromagnetic used in the present invention
Powders can also be manufactured according to known methods
The The shape of the ferromagnetic powder is not particularly limited, but
Usually acicular, granular, dice, rice granular (also called spindle shape)
U) and plate-like ones are used. Especially needle or
It is preferable to use spindle-shaped ferromagnetic powder. The present invention
In the case of a binder, a curing agent and a ferromagnetic powder,
Methyl ethyl keto used in the preparation of magnetic paints
Such as ethylene, dioxane, cyclohexanone, ethyl acetate, etc.
It is kneaded and dispersed together with the agent to form a magnetic layer-forming coating material. For kneading
The dispersion can be carried out according to the usual methods. As an abrasive usable in the magnetic layer of the present invention
Are α-alumina, β-alumina having an α conversion rate of 90% or more,
Fine diamond, silicon carbide, chromium oxide,
Lium, α-iron oxide, corundum, silicon nitride, silicon carbide
Elemental, titanium carbide, titanium oxide, silicon dioxide, nitriding
Known materials such as boron, mainly having a Mohs hardness of 6 or more
Used alone or in combination. In addition, these laboratories
A composite of abrasives (surface treated with other abrasives
May be used). These abrasives contain less than the main component.
It may contain other compounds or elements, but the main component
If it is 90% by mass or more, the effect is not changed. These laboratories
The powder size of the abrasive is preferably 0.01-1 μm, especially
Narrow particle size distribution to improve electromagnetic conversion characteristics
Is preferred. And if you want to improve durability,
Combine abrasives with different powder sizes,
Abrasives should have the same effect by widening the particle size distribution.
Is also possible. The tap density is 0.3 to 1.5 g / cc,
Moisture content is 0.1-5% by mass, pH is 2-11, specific surface area
1-40m ² / G is preferred. The laboratory used in the present invention
The shape of the abrasive can be needle-shaped, spherical, or dice-shaped.
However, those with corners in the shape are preferred because of their high polishing properties.
That's right. Specifically, AKP-10 and AKP- manufactured by Sumitomo Chemical Co., Ltd.
15, AKP-20, AKP-30, AKP-50, H
IT-20, HIT-30, HIT-50, HIT-6
0A, HIT-50G, HIT-70, HIT-80,
HIT-82, HIT-100, ERC made by Reynolds
-DBM, HP-DBM, HPS-DBM, Fujimi polishing
WA10000 manufactured by Yakuhin Co., UB20 manufactured by Uemura Kogyo Co., Japan
G-5, Kromex U2, Kromex U
1. TF100 and TF140 manufactured by Toda Kogyo Co., Ltd., IBIDEN
Beta Random Ultra Fine manufactured by Showa Mining Co., Ltd. B-
3 etc. are mentioned. These abrasives can be
It can also be added. Surface shape by adding to the lower layer
Control the state of the abrasive and the protruding state of the abrasive.
You can. Abrasive powder added to these magnetic layers and lower layers
Body size and quantity should of course be set to optimum values. The binder used in the present invention is cellulose.
Derivatives (eg, nitrocellulose, cellulose acetate, cells
Loose acetate), vinyl chloride / vinyl acetate copolymer
Resin (eg, vinyl chloride / vinyl acetate copolymer, vinyl chloride)
/ Vinyl acetate / vinyl alcohol copolymer, vinyl chloride
/ Vinyl acetate / maleic anhydride copolymer), vinyl chloride
Redene resin (eg, vinylidene chloride / vinyl chloride copolymer)
, Vinylidene chloride / acrylonitrile copolymer), poly
Reester resin (eg, alkyd resin, linear polyester)
), Acrylic resin (eg, acrylic acid / acrylonitrile)
Copolymer, methyl acrylate / acrylonitrile copolymer
Coalesced), polyvinyl acetal resin, polyvinyl butyra
Resin, phenoxy resin, epoxy resin, butadiene
/ Acrylonitrile copolymer, polyurethane resin, and
And urethane epoxy resin.
These can be used alone or in combination. Furthermore, when the binder of the present invention is used.
Is a combination of the above resin and a polyisocyanate compound.
The magnetic layer can also be cured. Polyisocyanate used
Examples of anate compounds include tolylene diisocyanate
, Xylylene diisocyanate, hexamethylene dii
3 moles of diisocyanate such as socyanate and trimethyl
Reaction product with 1 mol of roll propane, hexamethylene
3 moles of diisocyanate burette adduct,
Isocyanurate compound of 5 mol of Lylene Diisocyanate
, 3 mol of tolylene diisocyanate and hexamethylene
Diisocyanate 2 mol isocyanurate adduct
And polymers of diphenylmethane diisocyanate
Can be mentioned. Amount of binder used in the present invention
Is not particularly limited, but with respect to 100 parts by mass of the ferromagnetic powder.
Generally in the range of 10 to 100 parts by weight, preferably 15 to
It is used in the range of 50 parts by mass. The structure of the polyurethane resin is polyester.
Polyurethane, polyether polyurethane, polyether
Polyester polyurethane, polycarbonate polycarbonate
Tan, polyester polycarbonate polyurethane, polyester
Uses well-known materials such as licaprolactone polyurethane
Yes. Better for all the binders listed here
-COO if necessary to obtain high dispersibility and durability
M, -SO _Three M, -OSO _Three M, -P = O (OM) ₂ ,-
O-P = O (OM) ₂ (M is a hydrogen atom, or
Or alkali metal base), OH, NR ₂ , N ⁺ R _Three (R is
Hydrocarbon group), epoxy group, SH, CN, etc.
Copolymerize or add at least one polar group
It is preferable to use the one introduced by the reaction. This
The amount of such polar groups is 10 ^-1 -10 ^-8 Mol / g, preferred
Or 10 ^-2 -10 ^-6 Mol / g. The organic solvent used in the present invention can have any ratio.
With acetone, methyl ethyl ketone, methyl isobutyl ketone
, Diisobutyl ketone, cyclohexanone, isophor
Ketones such as Ron, tetrahydrofuran, methanol
, Ethanol, propanol, butanol, isobuty
Alcohol, isopropyl alcohol, methylcyclo
Alcohols such as hexanol, methyl acetate, acetic acid
Butyl, isobutyl acetate, isopropyl acetate, ethyl lactate
, Esters such as glycol acetate, glycol dimethyl
Ether, glycol monoethyl ether, dioxa
Glycol ethers such as benzene, toluene
, Xylene, cresol, chlorobenzene, etc.
Aromatic hydrocarbons, methylene chloride, ethylene chlora
Id, carbon tetrachloride, chloroform, ethylene chlorohydride
Chlorinated hydrocarbons such as phosphorus and dichlorobenzene, N,
Use N-dimethylformamide, hexane, etc.
Yes. These organic solvents are not necessarily 100% pure.
In addition to the main components, isomers, unreacted substances, side reactions, decomposition
It does not matter if impurities, oxides, moisture, etc. are included.
Yes. These impurities are preferably 30% or less, more preferably
Preferably it is 10% or less. The organic solvent used in the present invention is
It is preferable that the magnetic layer and the nonmagnetic layer are the same type.
Yes. The amount added may be changed. Surface on nonmagnetic layer
High tension solvent (cyclohexanone, dioxane, etc.)
To improve coating stability, specifically upper layer solvent composition
The arithmetic mean value of is not lower than the arithmetic mean value of the lower layer solvent composition
It is important. In order to improve dispersibility
Higher degree of polarity is preferable, and the dielectric constant is 1 in the solvent composition.
It is preferable that 50% or more of 5 or more solvents are contained. Ma
The solubility parameter is preferably 8-11.
Yes. The thickness of the magnetic layer of the magnetic recording medium of the present invention is
It is preferable that it is 0.01 μm or more and 0.25 μm or less.
Yes. When the thickness of the magnetic layer is less than 0.01 μm,
It is no longer a magnetic layer. Magnetic layer exceeds 0.25 μm
And the so-called self-demagnetization loss increases and at the same time
It becomes rough. Single or multiple magnetic layers can be achieved
Is possible. In the case of a plurality of magnetic layers, for example, JP-A-6-13.
A technology such as 9555 can be applied. The lower layer is mainly non-magnetic inorganic powder and binder.
The body is preferred. Nonmagnetic inorganic used for lower layer
Examples of the powder include metal oxide, metal carbonate, metal
No sulfate, metal nitride, metal carbide, metal sulfide, etc.
It can be selected from organic compounds. As an inorganic compound
For example, α-alumina, β-alloy with an α conversion rate of 90% or more
Mina, γ-alumina, θ-alumina, silicon carbide, oxidation
Chromium, cerium oxide, α-iron oxide, hematite, game
Tight, corundum, silicon nitride, titanium carbide, acid
Titanium fluoride, silicon dioxide, tin oxide, magnesium oxide,
Tungsten oxide, zirconium oxide, boron nitride, acid
Zinc fluoride, calcium carbonate, calcium sulfate, barium sulfate
Or molybdenum disulfide is used alone or in combination.
Used. Particularly preferred is a small particle size distribution and function.
Titanium dioxide, oxide oxide, etc.
Lead, iron oxide, and barium sulfate are more preferable.
Titanium oxide and alpha iron oxide. These non-magnetic inorganic powders
The average particle size is preferably 0.005 to 2 μm.
Depending on the combination of non-magnetic inorganic powders with different average particle sizes
Even with a single nonmagnetic inorganic powder,
It is possible to have the same effect. Especially preferred
The non-magnetic inorganic powder has an average particle size of 0.01 μm to 0.2
μm. In particular, the nonmagnetic inorganic powder is a granular metal oxide.
In some cases, an average particle size of 0.08 μm or less is preferable,
In the case of acicular metal oxide, the average major axis length is 0.3 μm
The following is preferable, and 0.2 μm or less is more preferable. T
Pop density is usually 0.05-2 g / ml, preferably
0.2 to 1.5 g / ml. Water content of non-magnetic inorganic powder
The rate is usually 0.1 to 5% by mass, preferably 0.2 to 3%.
The amount is more preferably 0.3 to 1.5% by mass. Non
The pH of the magnetic inorganic powder is usually 2 to 11, but the pH is
Particularly preferred is between 5.5 and 10. Nonmagnetic inorganic powder ratio
Surface area is usually 1-100m ² / G, preferably 5-8
0m ² / G, more preferably 10 to 70 m ² / G. The crystallite size of the nonmagnetic inorganic powder is 0.00
4 μm to 1 μm is preferable, 0.04 μm to 0.1 μm
Is more preferable. Using DBP (dibutyl phthalate)
The oil absorption is usually 5 to 100 ml / 100 g, preferably
10-80 ml / 100 g, more preferably 20-6
0 ml / 100 g. Specific gravity is usually 1-12, preferred
It is 3-6. Shape is acicular, spherical, polyhedral, plate
Any of the shapes may be used. Mohs hardness is preferably 4 or more and 10 or less
Good. SA (stearic acid) adsorption amount of non-magnetic inorganic powder
1-20 μmol / m ² , Preferably 2-15 μm
ol / m ² More preferably, 3 to 8 μmol / m ² In
The The pH is preferably between 3-6. these
The surface of the nonmagnetic inorganic powder is treated with Al ₂ O _Three , S
iO ₂ TiO ₂ , ZrO ₂ , SnO ₂ , Sb ₂ O _Three , Zn
O, Y ₂ O _Three Is preferred, but dispersibility is preferred.
The best is Al ₂ O _Three , SiO ₂ TiO ₂ , ZrO ₂ In
More preferred is Al ₂ O _Three , SiO ₂ , ZrO ₂ so
is there. These may be used in combination or alone
It can also be used. In addition, the table co-precipitated according to the purpose
A surface treatment layer may be used, and first alumina is present.
Later, the method of allowing silica to exist in the surface layer, or vice versa
It is also possible to take this method. In addition, the surface treatment layer
Depending on the layer, it may be a porous layer.
Is generally preferred. Nonmagnetic used in the lower layer of the present invention
As specific examples and production methods of inorganic powders, WO 98 /
The thing of 35345 is illustrated. Known by mixing carbon black in the lower layer
Lowering the surface electrical resistance Rs, which is the effect of
As well as the desired microbi
Kerr hardness can be obtained. Also, the lower layer is carbon
The effect of storing the lubricant is brought about by including black
It is also possible. The type of carbon black is rubber rubber
Furness, rubber thermal, color black, acetyl
Ren black or the like can be used. Lower carbo
Depending on the desired effect,
Should be optimized.
May be. The specific surface area of the underlying carbon black is generally
Usually 100-500m ² / G, preferably 150-40
0m ² / G, DBP oil absorption is 20 to 400 ml / 100
g, preferably 30 to 400 ml / 100 g. Mosquito
-The average particle size of Bon Black is usually 5nm-80n
m, preferably 10 to 50 nm, more preferably 10
~ 40 nm. The average particle size is larger than 80 nm.
-May contain a small amount of bon black. Carbon tube
The pH of the rack is 2 to 10, the water content is 0.1 to 10%,
The pop density is preferably 0.1 to 1 g / ml. Specific examples of carbon black used in the lower layer
Specific examples include those described in WO 98/35345.
It is done. These carbon blacks are the above non-magnetic inorganic powders.
50 masses with respect to powder (not including carbon black)
% Does not exceed 40% of the total mass of the nonmagnetic layer.
Can be used in a range. These carbon blacks are
Or they can be used in combination. Used in the present invention
Examples of carbon black that can be used are “carbon black”
Refer to “Handbook” (Carbon Black Association)
it can. Binder resin or moisture for the lower layer or back layer
Lubricants, dispersants, additives, solvents, dispersion methods, etc. are magnetic layers
Of them are applicable. In particular, the binder resin amount, type,
Regarding the amount and type of additive and dispersant added, it relates to the magnetic layer.
Known techniques can be applied. The magnetic recording medium of the present invention comprises a ferromagnetic powder, a crystal.
Mixtures, fatty acids, carbon black, abrasives, and more if desired
More used dispersants, lubricants, stabilizers, and antistatic
Add additives such as stoppers to the commonly used methyl ethyl
Dispersed in an organic solvent such as ketone or cyclohexanone
A magnetic coating and apply this magnetic coating on a non-magnetic support
And then dried. Usually magnetic layer
Is applied directly on the non-magnetic support, but the adhesive layer
Alternatively, it can be provided via an undercoat layer.
Such as ferromagnetic powder, additive, organic solvent and dispersion coating method
For details, refer to JP-A-52-108 (US Pat. No. 413).
5016), 52-804, 541-2805.
No., 54-46011, etc.
The The magnetic recording medium of the present invention is also a method described in the above publication.
Can be manufactured according to. In this specification, ferromagnetic powder and carbon
Various powder sizes such as black
Izu) is a high-resolution transmission electron micrograph and
It is obtained from the image analysis device. High resolution transmission electron microscope
Trace the outline of the powder in the mirror photograph with an image analyzer,
You can ask for Izu. That is, powder size is powder
Body shape is needle-like, spindle-like, columnar (however, the height is at the bottom
In the case of larger than the maximum major axis, etc., the major axis constituting the powder
The length of the powder, that is, the long axis length,
Columnar shape (however, the thickness or height is the longest diameter of the plate surface or bottom surface)
Smaller), the maximum major axis of the plate or bottom surface,
It is represented by a chopping plate diameter, and the shape of the powder is spherical, polyhedral,
It has a long axis that is a regular shape etc. and that constitutes powder from its shape.
When it cannot be determined, it is represented by the equivalent circle diameter. The average powder size of the powder is determined by the above powder.
An arithmetic average of body size, about 500 powders
It is obtained by carrying out the measurement as described above. Also, the
The average acicular ratio of the powder is the length of the minor axis of the powder in the above measurement.
Measure the length (the longest axis that is perpendicular to the major axis), that is, the minor axis length.
Specify the arithmetic average of the (long axis length / short axis length) values for each powder.
The Here, the minor axis length is the definition of the above powder size.
If the length of the minor axis constituting the powder is the same,
Refers to the thickness or height, respectively, in which case the major and minor axes
(Major axis length / minor axis length) is 1 for convenience.
I reckon. And if the shape of the powder is specific, for example
For the definition of powder size, average powder size is average
It is called the long axis length.
It is called the plate diameter, and the arithmetic average of (plate diameter / thickness to height) is the average
It is called plate ratio. In case of the same definition, average powder size is average
It is called particle size. The present invention will be described in more detail with reference to the following examples.
However, the scope of the present invention is not limited thereto.
Absent. The “parts” shown below are “mass” unless otherwise specified.
Part ". Example 1 <Preparation of Lower Layer Nonmagnetic Layer Forming Coating Solution and Magnetic Layer Forming Coating Solution> (Underlayer Nonmagnetic Layer Forming Component) Nonmagnetic Powder Titanium Dioxide TiO ₂ (Rutile type) 90 parts TiO ₂ Content: 90% or more Average particle size: 0.035 μm Specific surface area by BET method: 40 m ² / G pH: 7.0 DBP oil absorption: 27-38 ml / 100 g Mohs hardness: 6.0 Surface treatment layer: Al ₂ O _Three Carbon black (Mitsubishi Carbon Co., Ltd.) 10 parts Average particle size: 16 nm DBP oil absorption: 80 ml / 100 g pH: 8.0 Specific surface area by BET method: 250 m ² / G Volatile matter: 1.5% Vinyl chloride resin 12 parts (MR110, manufactured by Nippon Zeon Co., Ltd.) Polyester polyurethane resin (polar group -SO _Three 5 parts neopentyl glycol / caprolactone polyol / MDI = 0.9 / 2.6 / 1 (mass ratio) -SO _Three Na group: 1 × 10 ^-Four Containing mol / g-Polyisocyanate 3 parts (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.)-Butyl stearate 1 part-Stearic acid 2 parts-Oleic acid 1 part-Methyl ethyl ketone 150 parts-Cyclohexanone 50 parts [Upper layer Magnetic layer forming component) Ferromagnetic metal powder 100 parts Composition Fe: Co = 70: 30 (atomic ratio) Coercive force: 2300 Oe (184 kA / m) Specific surface area by BET method: 47 m ² / G Crystallite size: 177Å Saturation magnetization (σs): 145 A · m ² / Kg (emu / g) Average major axis length: 0.08 μm Needle ratio: 7.5 pH: 9.4 Water-soluble Na: 5 ppm Water-soluble Ca: 10 ppm Water-soluble Fe: 10 ppm ・ Magnetic surface treatment agent (phenylphosphone) Acid) 3 parts ・ Vinyl chloride copolymer 10 parts (MR-110, manufactured by Nippon Zeon Co., Ltd.) ・ Polyester polyurethane resin (polar group -SO _Three 2.5 parts neopentyl glycol / caproplactone polyol / MDI = 0.9 / 2.6 / 1 (mass ratio) -SO _Three Na group content: 1 × 10 ^-Four Mol / g-Polyisocyanate 2.5 parts (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.)-α-Alumina [(average particle size: 0.3 μm)] 10 parts-Dichromium trioxide 1 part-Carbon black [ (Average particle size: 0.10 μm)] 1.50 parts ・ Butyl stearate 1 part ・ Stearic acid 2 parts ・ Oleic acid 1 part ・ Methyl ethyl ketone 150 parts ・ Cyclohexanone 50 parts Each ingredient
After kneading each with a continuous kneader, use a sand mill.
And dispersed. Each of the obtained dispersion liquids
2.5 parts isocyanate in the non-magnetic layer dispersion, magnetic
Add 3 parts to the layer dispersion and add methylethyl each.
Add 40 parts of ketone and have an average pore size of 1 μm
The coating liquid for forming the nonmagnetic layer and the magnetic layer
Each of the forming coating solutions was prepared. <Preparation of Coating Solution for Backcoat Layer Formation> (Components for Backcoat Layer Formation) • Particulate carbon black powder 100 parts [BP-800 manufactured by Cabot, average particle size: 17 nm] • Coarse particle carbon black powder 10 parts [Thermal black manufactured by Kerncarb Corporation, average particle size: 230 nm] ・ 80 parts of calcium carbonate [Shiraishi Kogyo Co., Ltd., white glossy O, average particle size: 40 nm] ・ α-alumina 5 parts [Sumitomo Chemical Co., Ltd. HIT55 , Average particle diameter: 200 nm, Mohs hardness: 8.5] ・ Nitrocellulose resin 140 parts ・ Polyurethane resin 15 parts ・ Polyisocyanate 40 parts [Coronate L manufactured by Nippon Polyurethane Industry Co., Ltd.] ・ Polyester resin 5 parts ・ Dispersant: Copper oleate 5 parts: Copper phthalocyanine 5 parts: Barium sulfate 5 parts Ethyl ketone 2200 parts: 300 parts of butyl acetate: 600 parts Toluene [0045] connecting the respective components to form the back coat layer
After kneading with a second kneader, disperse using a sand mill.
It was. The obtained dispersion liquid is a film having an average pore diameter of 1 μm.
And filter the coating solution for backcoat layer formation.
Made. (Preparation of magnetic tape) Application for forming the obtained lower non-magnetic layer
The thickness after drying the liquid and the upper magnetic layer forming coating liquid is 1.70.
The thickness of the magnetic layer after drying so as to be μm
Aromatic polyamide for long length so that becomes 0.15 μm
Base as support (trade name: Mikutron thickness 4.4
(μm, manufactured by Toray Industries, Inc.) was applied simultaneously. in this case,
Aromatic polyamide support subjected to corona discharge treatment
But you can. Next, while both layers are still wet, 0.
Cobalt magnet with magnetic flux density of 3 Tesla and 0.15 Tes
Alignment processing is performed using a solenoid with magnetic flux density
It was. Thereafter, drying was performed to form a nonmagnetic layer and a magnetic layer. Thereafter, the other side of the polyamide support (magnetic
The back coating layer forming coating solution is dried on the opposite side of the layer)
Apply and dry so that the thickness after drying is 0.4 μm,
A non-magnetic layer is provided on one side of the support with a backcoat layer
And the magnetic layer, and the back coat layer on the other side
Magnetic recording laminated body rolls provided respectively were obtained. Obtained
Magnetic recording laminate roll in heat treatment zone at 120 ° C
At a tension of 29.4 N / m (3.0 kg / m) for 5 seconds
It was made to run for a while and heat processing was performed. After further heat treatment
The magnetic recording laminate roll is composed only of metal roll
7-stage calendar processing machine (temperature 90 ° C, 294kN /
m (Line pressure 300kg / cm))
And wound up with a tension of 5 kg. Magnetic recording
Before the recording laminate roll is slit,
It was stored in a heat treatment zone at a temperature of 70 ° C. for 24 hours. After saving
Slit the magnetic recording laminate roll of 3.8 mm width,
Computer data recording magnetic tape according to the present invention
Below, simply called magnetic tape). Obtained magnetic tape
Wrap 125m into DDS data cartridge
It is. Table of backcoat layer of magnetic tape obtained in this way
The surface roughness Ra was 6.5 nm. Examples 2 and 3, Comparative Examples 1 and 2 The amount of carbon black added to the magnetic layer of Example 1 is as follows.
To change the protrusion distribution of the protrusion height on the magnetic layer surface
I let you. Example 2 3.00 parts Example 3 0.75 parts Comparative Example 1 0 parts Comparative Example 2 5.00 parts The results are shown in Table 1. [Table 1] Evaluation of magnetic tape 1) Measurement of measurement of protrusion distribution of protrusion height on the surface of the magnetic layer is made by A DI manufactured by DIGITAL INSTRUMENT.
MF (AtomicForce Microscope
e) using NANOSCOPE III
Measured. 2) Interlayer friction coefficient (μ value) Interlayer friction coefficient is back-coated on a cylinder of 30 mmφ
Wrap around the cylinder surface with the carbon layer on top.
On top of that, the magnetic layer surface of the magnetic tape is a carbon layer to be measured
Apply the tape so that it touches the magnetic layer surface and the carbon layer surface.
Measure the coefficient of friction between the layers. Magnetic tape magnetic
10 g of load (T ₁ ) 10mm
Tension (T ₂ )
And repeatedly measure 10 passes (p). T
₂ / T ₁ Obtain the friction coefficient between the magnetic layer surface and the back layer surface
The 3) Reproduction output A single frequency signal of 13.5 MHz is output from the DDS drive.
Recording was performed at the optimum recording current, and the reproduction output was measured. Out
The force value is shown as a relative value with the reproduction output of Comparative Example 1 being 100.
It was. 4) Error rate The error rate is measured by [Media Logic Evaluate.
Meter ML4500B] measuring machine + DDS drive (H
(Manufactured by Hewlett-Packard)
Magnetic tape was performed as usual. 5) Dropout (DO) Optimum current value of 9MHz frequency signal with DDS drive
Write with the playback signal dropout counter
(Shibasoku Co., Ltd.) The measurement is done for 5 minutes,
Average number of DOs per minute of 15 μsec / -10 dB
Asked. 6) Running durability (running performance and powder falling, dirt) Repeated 1 minute length x 5000 passes using DDS drive
And then let it run. Due to clogging of the magnetic head during traveling
When the output drop of 6 dB occurs, measure the number of runs
The running performance was evaluated. At the same time, each guide in the DDS drive
Roll part, head cylinder part, capstan pinch
Observe the dirt caused by powder falling on each part such as the roller.
If too much powder falls, it may cause an increase in DO or clogging
Probability is high. ○ in the column of powder fall and dirt indicates no dirt, x
Means dirty. 7) Sendust bar wear amount The wear amount is measured by the materials Al, Fe, Si = aluminum, iron, shi
Rica = 5.4%, 85.0%, 9.6% (atomic ratio)
A square pillar (4.5mm square) wear bar made of material
Use and measure the amount of wear under the following conditions.・ Tape length 50m × 1 reciprocation ・ Tape speed 300mm / sec ・ Load 20g ・ Burlap angle 12 degrees ・ Temperature and humidity 23 ° C 50% RH [0052] Wear bar measured under these conditions is 40
The amount of wear is measured using a 0 × optical microscope. 8) Amount of head wear The amount of wear during actual driving is performed under the following conditions.
Yeah. Atmosphere in 21 ℃ 50% RH using DDS drive
Virgin 1 running in the atmosphere = head wear in 2.5 hours
Measure the amount of wear. Inverted quadrangular pyramid shape on head sliding surface before running
Engrave a shape consisting of shapes. After engraving the square pyramid ridgeline
Measure at 6 points including the diagonal line. The diagonal line of this pyramid is
Diagonal for distance 1 to the apex of the pyramid in the depth direction
The line distance is set to 7 (1: 7).
The amount of wear per hour is the reduced amount in the depth direction.
Asking. The results of the magnetic tape according to the present invention are shown in Table 1.
It is shown. Projection height on the surface of the magnetic layer in a magnetic tape
It was found that the contribution of the protrusion distribution of was extremely large. Main departure
Examples 1 to 3 in Ming show projection distribution of projection height according to the present invention.
Is shown. Error rate evaluation to show the reliability of information,
Friction coefficient value, reproduction output in electromagnetic conversion characteristics, wear characteristics
Effects such as performance, powder removal characteristics and running durability. This result
As a result, as shown in Examples 1 to 3, the A region, the B region, and the C region
Occupancy rate (A), (B) of each projection number a, b, c
(C) is the scope of the present invention, both of which have a low error rate
, Head wear is small, there is no powder fall (dirt), and traveling
The most balanced magnetic tape with excellent durability
The Comparative Example 2 with more (B) and (C) than the present invention is
The error rate also tends to be high, DO due to powder falling, etc.
This is a result of clogging and poor reliability. This is magnetic
If the number of protrusions on the surface of the conductive layer is large, the tip of the protrusion will be cut off.
It is thought that this phenomenon was caused
The Comparative Example 1 with less (B) and (C) than the present invention
Has a high error rate, large head wear,
The line endured in line durability and stopped at 638p.
Have In addition, the surface of the magnetic layer is scraped and many scratches are generated.
In addition, the durability of the magnetic layer is inferior. Thus, the magnetic tape of the present invention is
Is an error because the protrusion distribution of the protrusion height is within a specific range.
Low rate, high reliability, low friction coefficient and wear
Good results with low usability and high density magnetic
Ideal for recording computer data recording tape
The The magnetic recording medium of the present invention has the thickness of the entire medium.
Has a large recording capacity because it is very thin
I was able to make it. The total thickness of the magnetic recording medium is
Despite being very thin, the error rate is low and reliable.
Combined with good electromagnetic characteristics suitable for high-density recording
In addition, the wear resistance is low, the running durability and the easy-to-use tape
Has been realized. Furthermore, the upper magnetic layer is extremely thin and dense.
A magnetic recording medium having an advantageous configuration for recording can be provided economically.
The Therefore, the magnetic recording medium of the present invention has a computer data.
It can be advantageously used as a magnetic tape for data recording.
Further, the magnetic recording medium of the present invention can be applied to a narrow track pitch.
Magnetic tape for magnetic recording / reproducing system capable of recording / reproducing
Even when used as an off-track
Low data recording and reproduction with high reliability
It is.

Claims (1)

What is claimed is: 1. A magnetic recording medium having a magnetic layer containing a ferromagnetic powder and a binder on a support, wherein the magnetic layer surface has a projection distribution with the following projection heights: A magnetic recording medium characterized by the above. The number of protrusions a at the protrusion height of the protrusion distribution A region (20 nm or more and less than 30 nm) is 52.5 to 92.5% (A) The number of protrusions b of the protrusion height of the B region (30 nm or more and less than 40 nm) is 9 to 29 % (B) The number of protrusions c of the protrusion height in the C region (40 nm or more) is 0
18.5% (C) where 100 × a / (a + b + c) = A, 100 × b
/ (A + b + c) = B, 100 × c / (a + b + c) =
C.