JP2003022518A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating type magnetic recording medium having satisfactory electromagnetic transducing characteristics. SOLUTION: The magnetic recording medium wherein a magnetic layer containing at least ferromagnetic powder is provided on a substrate characteristically contains δ-alumina powder.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic tape and a magnetic device.
For magnetic recording media such as discs, especially coupled with ferromagnetic powder
Apply a magnetic coating mainly composed of an agent on a non-magnetic support to
Short wavelength in relation to coating-type magnetic recording media
Magnetic recording with excellent noise, output, and C / N in the area
It relates to the medium. In addition, M using the magnetoresistive effect for reproduction
Particularly suitable for use in a system using an R head.
The present invention relates to a magnetic recording medium for high density recording including a magnetic layer. [0002] 2. Description of the Related Art A coating type magnetic recording medium is polyethylene.
Non-magnetic support such as terephthalate, and strong strength
Magnetism in which magnetic powder is uniformly dispersed in resin binder liquid
It is composed of a magnetic layer formed by applying a paint. Magnetic field
As conventional powder, γ-Fe₂O_ThreeFe-Co alloy powder
Acicular ferromagnetic powder such as
Hexagonal ferrite ultra-fine magnetic powder aimed at improving density
Products using powder have been developed and some are being put to practical use
ing. Data capacity handled in the field of magnetic disks
Floppy (registered trademark) today, the amount is increasing rapidly
It is desired to increase the capacity of the disk. Also of magnetic tape
In recent years also in the field, minicomputer, personal
Office computers such as computers and workstations
With the spread of computers, it has become a computer as an external storage medium.
Magnetic tape for recording computer data (IWAYU
Research on backup tapes) has been actively conducted.
For practical application of magnetic tape for such applications,
In addition to the downsizing of computers and increased information processing capabilities.
In order to achieve large recording capacity and miniaturization, recording
There is a strong demand for improved capacity. Conventionally, a magnetic head that uses electromagnetic induction as its operating principle.
Inductive magnetic heads are used and are in widespread use. But
In addition, there is a limit to using it in high-density recording / playback areas.
ing. In other words, in order to obtain a large playback output
It is necessary to increase the number of coil turns of the head, but the inductor
Increase the resistance at high frequencies and as a result,
There was a problem that power decreased. In recent years, MR (magnetoresistance)
Proposal of a playback head based on the working principle, hard disk, etc.
Has begun to be used in. MR head is an induction magnetic head
Reproduction output several times higher than
Equipment noise such as impedance noise is not used.
It is greatly reduced by greatly reducing the noise of magnetic recording media.
It has become possible to obtain a clear S / N ratio. In other words
Reduces magnetic recording medium noise that was hidden behind conventional equipment noise
If this is done, good recording and playback can be achieved, and high-density recording characteristics can be dramatically improved.
Can be improved. In addition, improvement of electromagnetic conversion characteristics and running durability
In order to ensure the properties, it is necessary to add abrasives to the magnetic layer.
It has been broken. For example, typically a module such as α-alumina.
It is well known that abrasives with high hardness are used for the magnetic layer.
It is being done. However, these abrasives
It is difficult to ensure the smoothness of the magnetic layer surface.
The problem that it is difficult to effectively improve the conversion characteristics
was there. In particular, MR heads are used for reproducing magnetic recording media.
If so, the effect of the presence of abrasives will increase and S / N degradation will
There was also a problem that it was easy to cause. The object of the present invention is to provide electromagnetic
To provide a coating type magnetic recording medium having good conversion characteristics
is there. [0006] The object of the present invention is to provide a support.
Magnetic recording with a magnetic layer containing at least ferromagnetic powder on it
The recording medium contains δ alumina powder.
This can be achieved by a magnetic recording medium. Preferred of the present invention
The following aspects are as follows. (1) The δ alumina powder has an average particle size of 5 to 30 nm.
The above magnetic recording medium. (2) The dry thickness of the magnetic layer is 0.01 to 0.2 μm.
The magnetic recording medium. (3) Nonmagnetic powder and bond between the support and the magnetic layer
A non-magnetic layer mainly composed of an agent resin is provided.
Ferromagnetic powder having a dry thickness of 0.01 to 0.2 μm
Is a hexagonal ferrite with an average plate diameter of 10 to 35 nm
Ferromagnetic with powder or average powder size of 80nm or less
The magnetic recording medium as described above, which is a metal powder. [0007] BEST MODE FOR CARRYING OUT THE INVENTION
It is characterized by containing Mina powder, δ alumina powder is
Added to at least one of the components of the magnetic recording medium.
You can. For example, δ alumina powder is a magnetic recording medium
Constituent layers, for example, magnetic layer, non-magnetic layer, back layer, undercoat
It can be added to at least one of the layers. Ma
Further, the δ alumina powder may be added to the support. δ
Alumina powder is at least from the magnetic layer, especially from the support.
It is preferably added to a magnetic layer provided far away. Δ alumina powder is mainly composed of crystal structure.
Al with delta structure₂O_ThreeIt means what is. δ aluminum
Na powder is obtained by flame hydrolysis of anhydrous aluminum chloride.
Can be manufactured. Δ a obtained in this way
Lumina powder has fine primary particles, chemical purity
Is very high, BET specific surface area is 100 ± 15m ²
It is characterized by being as high as / g. Δ alumina powder
The Mohs hardness is about 8 which is smaller than α-alumina.
Furthermore, the δ alumina powder has the following characteristics. Appearance is white
Color, true specific gravity is about 3.2, pH value is 4.5-5.5 (underwater
4% dispersion), and the isoelectric point is 9.0 (pH). like this
Δ alumina powder is made by Nippon Aerosil Co., Ltd.
Available as minimumOxide C. When δ alumina powder is added to the magnetic layer,
Usually, 0.1-30.
0 parts by weight, preferably 0.2-15.0 parts by weight
Good. In the present invention, δ alumina powder is applied to the lower layer described later.
In the case of addition, it is not necessary to pass 100 parts by mass of nonmagnetic powder.
Usually 0.1 to 99 parts by weight, preferably 1 to 90 parts by weight
It is good to be. δ alumina powder has an average particle size of 5 to 30n
m is preferable. Average particle size smaller than 5nm
It is difficult to manufacture and even if it is obtained
It is also difficult to disperse uniformly in the binder. Also,
If the average particle diameter exceeds 30 nm, the surface smoothness of the magnetic layer
Especially, the magnetic layer is thinned to 0.01-0.2 μm,
The tendency of electromagnetic conversion characteristics to deteriorate when played back with an MR head
There is a direction. [Magnetic layer] The magnetic recording medium of the present invention has a ferromagnetic powder.
The magnetic layer may be provided on only one side of the support or on both sides.
Yes. Magnetic layers provided on one side can be single layers or
Multiple layers having different compositions may be used. Also, between the support and the magnetic layer
A nonmagnetic layer (also referred to as a lower layer) may be provided. The present invention
The structure in which the magnetic layer is provided on the lower layer is preferable. This place
The combined magnetic layer is also referred to as an upper layer or an upper magnetic layer. Upper layer is lower
After simultaneous or sequential application of the layers, the lower layer is provided in a wet state
Even when wet-on-wet (W / W)
For wet-on-dry (W / D) installation after drying
But it can be formed. W / W is preferable in terms of production yield.
In W / W, the upper layer / lower layer can be formed simultaneously.
Can effectively utilize surface treatment processes such as
In addition, the surface roughness of the upper magnetic layer can be improved. The ferromagnetic powder used in the present invention is a strong powder.
Magnetic iron oxide, ferromagnetic cobalt modified iron oxide, CrO₂powder
Powder, hexagonal ferrite powder and various ferromagnetic metal powders, etc.
Is used, but ferromagnetic metal powder or hexagonal blowjob
Is preferred. Below, ferromagnetic metal powder and hexagonal
The crystal ferrite powder will be described in detail. [Ferromagnetic metal powder] As the ferromagnetic metal powder, α-Fe
Ferromagnetic metal powder containing as a main component is preferable. Ferromagnetic metal
In addition to predetermined atoms, the powder contains Al, Si, Ca, Mg, T
i, Cr, Cu, Y, Sn, Sb, Ba, W, La, C
e, Pr, Nd, P, Co, Mn, Zn, Ni, Sr,
It may contain atoms such as B. In particular, Al, C
a, Mg, Y, Ba, La, Nd, Sm, Co, Ni
It is preferable to include at least one other than α-Fe.
Co is increased in saturation magnetization and decreased when alloyed with Fe.
This is particularly preferable because the magnetism is improved. Co content is Fe
1 atomic% to 40 atomic% is preferable and more preferable
Or 15 atomic% to 35 atomic%, more preferably 20 atoms.
% Of children to 35 atomic percent. The content of rare earth elements such as Y is
1.5 atomic% to 12 atomic% are preferable, and more preferable
Is 3 atomic% to 10 atomic%, more preferably 4 atomic% to 9
Atomic%. Al is preferably 1.5 to 12 atomic%
More preferably 3 atomic% to 10 atomic%, more preferably
It is preferably 4 atom% to 9 atom%. Rare earths including Y
Al functions as a sintering inhibitor and is used in combination
By doing so, a higher sintering prevention effect can be obtained. these
Ferromagnetic powders contain dispersants, lubricants, and surface activity described later.
Pre-dispersion with an agent, antistatic agent, etc.
It doesn't matter. Specifically, Japanese Patent Publication No. 44-14090
No. 45, No. 45-18372, No. 47-2206
No. 2, No. 47-22513, No. 46-284
66, Shoko 46-38755, Shoko 47-42
86, Shoko 47-12422, Shoko 47-17
No. 284, JP-B 47-18509, JP-B 47-1
No. 8573, No. 39-10307, No. 46-
39639, U.S. Pat.
No. 1341, No. 3100194, No. 324005
No. 3,33889014 and the like. The ferromagnetic metal powder contains a small amount of hydroxide,
May contain oxides. Known production of ferromagnetic metal powder
What was obtained by the manufacturing method can be used, and the following
A method can be mentioned. Moisture treated with sintering prevention
Fe oxide by reducing iron oxide and iron oxide with a reducing gas such as hydrogen
Alternatively, a method for obtaining Fe-Co particles, a complex organic acid salt
(Mainly oxalate) and reducing gas such as hydrogen
Method for thermally decomposing metal carbonyl compounds, strong
Sodium borohydride, hypophosphorous acid in aqueous magnetic metal solution
Reduce by adding a reducing agent such as acid salt or hydrazine
Process, evaporating the metal in a low-pressure inert gas to produce a powder
How to get. Ferromagnetic gold obtained in this way
The genus powder is subjected to a known slow oxidation treatment. Hydrous iron oxide, iron oxide
Reduced with a reducing gas such as hydrogen, inert with oxygen-containing gas
An oxide film is formed on the surface by controlling the gas partial pressure, temperature and time.
The method of forming is preferable because the amount of demagnetization is small. The ferromagnetic metal powder of the magnetic layer of the present invention is changed to BET.
Specific surface area (S_BET) 40-130m²/
g, preferably 45 to 120 m²/ G. 4
0m ²/ G or less, the noise becomes high, 130m²/ G or more
Above, it is difficult to obtain a smooth surface, which is not preferable. Magnet of the present invention
The crystallite size of the ferromagnetic powder in the conductive layer is 50 to 180 mm
Preferably 60 to 170 mm, more preferably 80 to
It is 165cm. The average powder size of the ferromagnetic powder, i.e. flat
The average axial length or average plate ratio is preferably 30-80 nm.
More preferably, it is 35 to 75 nm. Average of ferromagnetic powder
The acicular ratio or average plate ratio is preferably 3 to 15,
Is preferably 3 to 10. Saturation magnetization σs of ferromagnetic metal powder
Is usually 80-170A ・ m²/ Kg, preferably
90 ~ 160A ・ m²/ Kg, more preferably 95-
150A ・ m²/ Kg. Coercive force of ferromagnetic metal powder
Is preferably 135 to 279 kA / m, more preferably
143 to 239 kA / m. The moisture content of the ferromagnetic metal powder is 0.1 to 2 mass.
% Is preferable. Ferromagnetic powder depending on the type of binder
It is preferable to optimize the moisture content of the powder. P of ferromagnetic powder
H is optimized by the combination with the binder used.
Are preferred. The range is 6-12, preferably
Is 7-11. Ferromagnetic metal powder SA (stearin
Acid) adsorption amount (a measure of the basic point of the surface) is 1-15 μmo
l / m², Preferably 2 to 10 μmol / m²Even better
Preferably 3-8μmol / m²It is. Stearic acid absorption
When using a ferromagnetic metal powder with a large amount of deposit, absorb strongly on the surface.
Magnetic recording media can be created by modifying the surface with organic materials
Are preferred. Ferromagnetic powder has soluble Na, Ca, F
e, Ni, Sr, NH_Four, SO_Four, Cl, NO₂, NO_ThreeNa
Any inorganic ion may be included. These are essentially
It is preferable that there is not. The total sum of each ion is 300 ppm or less
If it is, it will not affect the characteristics. Also used in the present invention
Ferromagnetic powder that can be used preferably has fewer holes
The value is 20% by volume or less, more preferably 5% by volume or less.
is there. As for the shape, the powder size and magnetic
Any of needle-like, rice-grained, or spindle-shaped if it satisfies the characteristics
It does n’t turn. SFD of ferromagnetic powder itself (switchchin
g-field distribution) is small
Is preferable, and it is necessary to reduce the Hc distribution of the ferromagnetic powder.
There is. When tape SFD is small, magnetization reversal
Peak shift is reduced, and high-density digital magnetic recording
Suitable for recording. In order to reduce the Hc distribution,
Improve the particle size distribution of goethite
Monodisperse α-Fe₂O_ThreeTo prevent sintering between particles
There are ways to stop it. [Hexagonal ferrite magnetic powder] Hexagonal ferrite magnetic powder
There are no particular restrictions on the powder, but iron or iron can be used.
BaFe whose converted metal has an average valence of 3₁₂O₁₉Cost
The crystal structure or basic composition represented is M-type magneto
Hexagonal ferrite; bivalent metal (hereinafter referred to as M)
Ba)₂Fe₁₆O₂₇Crystal structures represented by
Structure or basic composition is W-type magnetoplumbite hexagonal
Ferrite: BaMFe₆O₁₁Crystal structure represented by
Or the basic composition is Y-type magnetoplumbite hexagonal
Ferrite; Ba_ThreeM₂Fe_{twenty four}O₄₁Crystal structure represented by
Or the basic composition is Z-type magnetoplumbite hexagonal
Ferrite; and the surface of these hexagonal ferrites
Spinel ferrite is compounded epitaxially
The so-called composite type hexagonal ferrite is preferred.
Yes. Here, the composition of the hexagonal ferrite magnetic powder
M in the formula and divalent constituting spinel ferrite
As the metals, Co, Fe, Ni, Mn, Mg, Cu
And Zn. In particular, W-type and composite-type hexagonal systems
For ferrite, bulk composition or powder surface composition
In transition metals and oxygen with less alkaline metals
Is rich in acid-base between powder surface and binder
The surface chemical interaction due to
Large amount of magnetization and rich magnetic cohesion. The present invention
This also works effectively for such systems. Method for producing the above hexagonal ferrite magnetic powder
Methods include glass crystallization, hydrothermal synthesis, coprecipitation,
Any method such as the Lux method may be used. Any
The method also has a sharp shape distribution and particle size distribution.
Can be found as magnetic powder for magnetic recording media.
It is important to achieve high density recording. The hexagonal ferrite powder used in the present invention
The average plate diameter varies depending on the recording density, but 10 to 35 n
m is preferable, and 15 to 32 nm is more preferable. Flat
If the flat plate diameter is less than 10 nm, the amount of magnetization decreases significantly.
Not suitable for recording media, noise component exceeds 35nm
It is not suitable for high density recording. Here, the plate diameter is hexagonal
The maximum hexagonal diameter of the hexagonal column bottom of the crystalline ferrite magnetic powder
Meaning, the average plate diameter is the arithmetic average. On the other hand, the thickness of the hexagonal ferrite powder
The average is the arithmetic average of the plate ratio expressed by the ratio of the plate diameters
The plate ratio is usually 2 to 10, preferably 2 to 7, more preferably
Preferably it is 2-5. If the ratio is less than 2, the magnetic powder
Is difficult to produce, and if it exceeds 10, the magnetic cohesive force is reduced.
Because it becomes more dominant than scattered power, it becomes difficult to disperse.
is there. The variation coefficient of the plate diameter is 100 × σ / average.
It is obtained from the plate diameter. The coefficient of variation of the plate diameter is preferably 35% or less
Good. The variation coefficient of the plate ratio is preferably 30% or less. This
Is obtained from 100 × σ / average plate ratio.
σ represents the standard deviation of the plate diameter or plate ratio. In the present specification, hexagonal ferrite powder
Various powder sizes (such as powder and carbon black)
(Hereinafter referred to as “powder size”) is a high-resolution transmission electron microscope.
It is calculated | required from a microscopic photograph and an image analyzer. High resolution transparency
Trace the outline of the powder in the oversized electron micrograph using an image analyzer.
Thus, the size of the powder can be obtained. That is, the powder
Izu has a needle shape, spindle shape, and columnar shape (however,
If the height is larger than the maximum major axis of the bottom)
The length of the major axis, that is, the major axis length, and the shape of the powder
The shape is plate or columnar (however, the thickness or height is the plate surface or the bottom
Smaller than the maximum major axis of the surface)
It is represented by the maximum long diameter, that is, the plate diameter.
It is in the shape of a face, unspecified shape, etc., and the powder is composed of the shape
When the major axis to be identified cannot be specified, 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.
That is, the short axis length is measured, and (long axis length / short axis length) of each powder
The arithmetic mean of the values of. Here, the minor axis length is the above powder
In the definition of size, the length of the short axis that constitutes the powder
In the same case, it refers to the thickness or height, respectively.
In this case, there is no distinction between long axis and short axis.
Long) is regarded as 1 for convenience. And the shape of the powder is specified
For example, in the case of the definition of the above powder size,
The uniform powder size is called the average major axis length.
The uniform powder size is referred to as the average plate diameter, (plate diameter / thickness to high
The arithmetic average of (a) is called the average plate ratio. In the case of the same definition
The average powder size is called the average particle size. The hexagonal ferrite powder has a saturation magnetization σs.
40 ~ 80A ・ m²/ Kg, coercive force Hc is 135 to 44
0 kA / m, specific surface area by BET method (S_BET) Is 40
~ 80g / m²The pH of the magnetic powder is a combination with the binder used.
It is preferable to optimize by combination, but usually pH
It is 4 to 12, preferably 5.5 to 10. [Lower layer] Next, a detailed description of the lower layer will be given.
I will explain. For the lower layer, non-magnetic inorganic powder and binder
The main body is preferable. Non-magnetic used for lower layer
Examples of the machine powder include metal oxide, metal carbonate, and gold.
Metal sulfate, metal nitride, metal carbide, metal sulfide, etc.
It can be selected from inorganic compounds. With inorganic compounds
For example, α-alumina and β-a with an α conversion rate of 90% or more.
Lumina, γ-alumina, θ-alumina, silicon carbide, acid
Chromium oxide, cerium oxide, α-iron oxide, hematite, gel
-Tight, corundum, silicon nitride, titanium carbide,
Titanium oxide, silicon dioxide, tin oxide, magnesium oxide
, Tungsten oxide, zirconium oxide, boron nitride
Elemental, zinc oxide, calcium carbonate, calcium sulfate, sulfuric acid
Barium, molybdenum disulfide, etc. alone or in combination
Used. Particularly preferred is a small particle size distribution.
Well, because there are many means for imparting functions, titanium dioxide,
Zinc oxide, iron oxide, and barium sulfate are more preferable.
Are titanium dioxide and alpha iron oxide. These non-magnetic inorganic
The average particle size of the powder is preferably 0.005 to 2 μm,
If necessary, combine nonmagnetic inorganic powders with different average particle sizes.
Wide particle size distribution even with single non-magnetic inorganic powder
Thus, the same effect can be achieved. Especially preferred
The average particle size of the non-magnetic inorganic powder is from 0.01 μm to
0.2 μm. In particular, the non-magnetic inorganic powder is a granular metal acid.
In the case of chemicals, the average particle size is preferably 0.08 μm or less.
In the case of acicular metal oxide, the average major axis length is 0.3.
μm or less is preferable, and 0.2 μm or less is more preferable
Yes. Tap density is usually 0.05-2g / ml, preferred
Or 0.2 to 1.5 g / ml. Non-magnetic inorganic powder
The water content is usually 0.1 to 5% by mass, preferably 0.2 to
3% by mass, more preferably 0.3-1.5% by mass
The The pH of the nonmagnetic inorganic powder is usually 2 to 11,
The pH is particularly preferably between 5.5 and 10. Nonmagnetic inorganic powder
S at the end_BETUsually 1-100m²/ G, preferably 5
80m²/ G, more preferably 10 to 70 m²/ G
The The crystallite size of the nonmagnetic inorganic powder is 0.004 μm ~
1 μm is preferable, and 0.04 μm to 0.1 μm is more preferable.
Good. Oil absorption using DBP (dibutyl phthalate)
Is usually 5 to 100 ml / 100 g, preferably 10 to
80 ml / 100 g, more preferably 20-60 ml /
100 g. The specific gravity is usually 1 to 12, preferably 3
~ 6. The shape is needle-like, spherical, polyhedral, plate-like
It's okay. Mohs hardness of 4-10 is preferred
Good. SA (stearic acid) adsorption amount of non-magnetic inorganic powder
1-20 μmol / m², Preferably 2-15 μmo
l / m²More preferably, 3 to 8 μmol / m²In
The The pH is preferably between 3-6. these
The surface of the nonmagnetic inorganic powder is treated with Al₂O_Three, S
iO₂TiO₂, ZrO₂, SnO₂, Sb₂O_Three, Zn
O, Y₂O_ThreeIs preferred. Especially preferred for dispersibility
Inano is Al₂O_Three, SiO₂TiO₂, ZrO₂Is
More preferred is Al₂O_Three, SiO₂, ZrO₂In
The These may be used in combination or used alone
You can also. Also, co-precipitated surface according to purpose
A treated layer may be used, or first after alumina is present
To make silica in the surface layer, or vice versa
A method can also be taken. The surface treatment layer is suitable for the purpose.
However, it may be a porous layer.
Generally preferred. Non-magnetic material used in the lower layer of the present invention
As specific examples and production methods of the machine powder, WO98 / 3
The thing of 5345 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. S of the lower carbon black_BETUsually
100-500m²/ G, preferably 150-400m²
/ G, DBP oil absorption is 20-400ml / 100g, good
It is preferably 30 to 400 ml / 100 g. carbon
The average particle size of black is usually 5 to 80 nm, preferably
10 to 50 nm, more preferably 10 to 40 n.
m. Carbon block with an average particle size greater than 80 nm
May contain a small amount of racks. Carbon black
pH 2-10, moisture content 0.1-10%, tap 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. These carbon blacks are the above nonmagnetic inorganic powders
50% by mass (not including carbon black)
Range that does not exceed 40% of the total mass of the nonmagnetic layer.
Can be used in enclosures. These carbon blacks can be used alone or
Or they can be used in combination. Used in the present invention
For example, carbon black
”(Carbon Black Association)
Yes. In the lower layer, an organic powder is used depending on the purpose.
It can also be added. For example, acrylic styrene tree
Fat powder, benzoguanamine resin powder, melamine resin powder
Powders such as phthalocyanine pigments
Tin resin powder, polyester resin powder, polyamide
Resin powder, polyimide resin powder, polyfluoroethylene
Resin can also be used. The production method is disclosed in JP-A-62.
-18564, described in JP-A-60-255827
Something like that can be used. Binder tree for lower layer or back layer described later
Fats, lubricants, dispersants, additives, solvents, dispersion methods, etc.
The magnetic layer described below can be applied. In particular, binding
Agent amount, type, additive, dispersant addition amount, type
For example, known techniques relating to the magnetic layer can be applied. [Binder] As a binder used in the present invention.
Conventionally known thermoplastic resins, thermosetting resins, reactive trees
Fats and mixtures thereof are used. As a thermoplastic resin
Has a glass transition temperature of −100 to 150 ° C., a number average molecule
The amount is 1,000 to 200,000, preferably 10,000
00 to 100,000, degree of polymerization about 50 to 1000
belongs to. Examples include vinyl chloride, vinegar
Vinyl acid, vinyl alcohol, maleic acid, acrylic
Acid, acrylic acid ester, vinylidene chloride, acryloni
Tolyl, methacrylic acid, methacrylic acid ester, styrene
, Butadiene, ethylene, vinyl butyral, vinyl
Contains acetal, vinyl ether, etc. as structural units
Polymer or copolymer, polyurethane resin, various rubbers
There is resin. Also, thermosetting resin or reactive resin
Phenolic resin, epoxy resin, polyurethane curing
Mold resin, urea resin, melamine resin, alkyd resin, active resin
Ryl reaction resin, formaldehyde resin, silicone resin
Fat, epoxy-polyamide resin, polyester resin and
Mixture of socyanate prepolymer, polyester poly
A mixture of all and polyisocyanate, polyurethane and
And a mixture of polyisocyanates. these
For the resin, “Plastic Handbrush” issued by Asakura Shoten
Is described in detail. In addition, known electron beam hardness
It is also possible to use chemical resins for each layer. these
Examples and production methods thereof are described in JP-A-62-2256219.
Are described in detail. These resins can be used alone or in combination
Can be used together, but vinyl chloride is preferred
Resin, vinyl chloride vinyl acetate copolymer, vinyl chloride acetic acid
Vinyl vinyl alcohol copolymer, vinyl chloride vinyl acetate
Maleic anhydride copolymer, at least one selected from
A combination of seeds and polyurethane resin, or
A combination of reisocyanates can be mentioned. The structure of the polyurethane resin is polyester.
Polyurethane, polyether polyurethane, polyether
Polyester polyurethane, polycarbonate polyure
Tan, Polyester Polycarbonate, Polyurethane, Poly
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_ThreeM, -OSO_ThreeM, -P = O (OM)₂,-
O-P = O (OM)₂(M is a hydrogen atom, or
Or alkali metal base), -NR₂, -N⁺R_Three(R is charcoal
Hydrogen group), epoxy group, -SH, -CN, etc.
Copolymerize or attach at least one polar group
It is preferable to use one introduced by addition reaction. This
The amount of such polar groups is 10^-1-10^-8Mol / g, preferred
Or 10^-2-10^-6Mol / g. These polar groups
Outside, at least one polyurethane molecule terminal, total
It is preferable to have two or more OH groups. OH group is hard
3D network by cross-linking with polyisocyanate
Since it forms a structure, it is more preferable that it is contained in the molecule.
In particular, OH groups are more reactive with curing agents at the molecular ends.
This is preferable. Polyurethane has 3 OH groups at the molecular ends.
It is preferable to have at least 4
Is preferred. In the present invention, when using polyurethane
The glass transition temperature is usually -50 to 150 ° C.
Or 0-100 ° C, particularly preferably 30-100 ° C,
The elongation at break is 100-2000%, and the break stress is usually 0.
05-10Kg / mm²(≈0.49 to 98 MPa),
Yield point is 0.05-10Kg / mm²(≒ 0.49-9
8 MPa) is preferred. Having such physical properties
Thus, a coating film having good mechanical properties can be obtained. Specific examples of these binders used in the present invention
A typical example is a union catalyst as a vinyl chloride copolymer.
-VAGH, VYHH, VMCH, VAG manufactured by BYTE
F, VAGD, VROH, VYES, VYNC, VMC
C, XYHL, XYSG, PKHH, PKHJ, PKH
C, PKFE, manufactured by Nissin Chemical Industry Co., Ltd., MPR-TA, MP
R-TA5, MPR-TAL, MPR-TSN, MPR
-TMF, MPR-TS, MPR-TM, MPR-TA
O, 1000 W manufactured by Electrochemical Co., Ltd., DX80, DX81, D
X82, DX83, 100FD, ZEON Corporation MR-
104, MR-105, MR110, MR100, MR
555, 400X-110A, as polyurethane resin
Nippon Polyurethane N2301, N230
2, N2304, Pandex T-5 manufactured by Dainippon Ink
105, T-R3080, T-5201, Barnock D
-400, D-210-80, Crisbon 6109,7
209, Byron UR8200, UR830 manufactured by Toyobo Co., Ltd.
0, UR-8700, RV530, RV280, Dainichi
Chemical polycarbonate polyurethane, diferamin
4020, 5020, 5100, 5300, 9020,
9022, 7020, polyurethane manufactured by Mitsubishi Kasei Co., MX
5004, Sanyo Kasei Polyurethane, Samprene SP
-150, Asahi Kasei polyurethane, Saran F310,
F210 etc. are mentioned. The binder used in the nonmagnetic layer is a nonmagnetic inorganic
The binder used for powders and magnetic layers is hexagonal.
The range of 5 to 50% by mass with respect to the ferrite magnetic powder is preferable.
Preferably, it is used in the range of 10 to 30% by mass. PVC
5-30% by mass when using a nyl resin, polyureta
2 to 20% by mass when using polyisocyanate, polyisocyanate
Use a combination of these in the range of 2-20% by mass
It is preferable that the
If rust corrosion occurs, only polyurethane or poly
It is possible to use only urethane and isocyanate.
is there. The magnetic recording medium of the present invention is composed of two or more layers.
The amount of binder, the vinyl chloride resin in the binder
Fat, polyurethane resin, polyisocyanate, or
Other resin amount, each resin molecule forming the magnetic layer
Quantity, polar group quantity, or physical properties of the resin mentioned above
Of course, it is possible to change for each layer as needed
Rather, each layer should be optimized and
A known technique can be applied. For example, binder in each layer
To reduce the scratches on the surface of the magnetic layer when changing the amount
Increasing the amount of binder in the magnetic layer is effective.
In order to improve the head touch against the
To increase flexibility by increasing the amount of binder in the adhesive layer
it can. The polyisocyanate used in the present invention and
For example, tolylene diisocyanate, 4,4'-diphe
Nylmethane diisocyanate, hexamethylene diisocyanate
Anate, xylylene diisocyanate, naphthylene
1,5-diisocyanate, o-toluidine diisocyanate
Nate, isophorone diisocyanate, triphenyl
Isocyanates such as tan triisocyanate,
Formation of these isocyanates and polyalcohols
Products and products formed by condensation of isocyanates.
Examples include reisocyanate. These isocyanes
For example, Nippon Polyuree
Made by Tan, Coronate L, Coronate HL, Coronate
2030, Coronate 2031, Millionate MR, Mi
Lionate MTL, Takeda Pharmaceutical Co., Ltd., Takenate D-10
2, Takenate D-110N, Takenate D-200,
Takenate D-202, manufactured by Sumitomo Bayer, Death Mod
L, Death Module IL, Death Module N, Death
There are modules HL, etc., these can be used alone or in a curing reaction
Using two or more combinations using gender differences
Each layer can be used. [Carbon black, abrasive] Magnet of the present invention
Carbon black used for the protective layer is a rubber furnace.
, Rubber thermal, color black, acetylene rubber
A rack, etc. can be used. S _BET5 to 500
m²/ G, DBP oil absorption is 10 to 400 ml / 100
g, average particle diameter is 5 nm to 300 nm, pH is 2 to 1
0, moisture content is 0.1 to 10%, tap density is 0.1 to 1
g / cc is preferred. Specifically, WO 98/353
The thing of 45 is mentioned. Carbon black is an antistatic, anti-friction material for the magnetic layer.
Functions such as reducing the friction coefficient, imparting light-shielding properties, and improving film strength
These differ depending on the carbon black used. Obedience
Thus, when the present invention has a multilayer structure, the type of each layer,
Change the amount and combination, particle diameter, oil absorption, conductivity, pH
Use properly according to the purpose based on the above-mentioned characteristics.
Of course, it is possible to optimize,
Kimono. In the present invention, the abrasive is used alone or in the magnetic layer.
It can be used with alumina. Α as an abrasive
Α-alumina, β-alumina, carbonization with a conversion rate of 90% or more
Ion, chromium oxide, cerium oxide, α-iron oxide, chorane
Dam, artificial diamond, silicon nitride, silicon carbide, titanium
Carbide, titanium oxide, silicon dioxide, boron nitride,
Mostly known materials with Mohs hardness of 6 or more are used alone or
Used in combination. For example, δ alumina and α-a
It is also preferable to use a mixture of lumina, diamond, etc.
Yes. In addition, composites of these abrasives (polishing agents other than
You may use what was surface-treated with the abrasive | polishing agent. these
This abrasive contains compounds or elements other than the main component
In some cases, if the main component is 90% or more, the effect will change.
There is no. These abrasives have an average particle size of 0.01 to 2 μm.
It is preferable to improve the electromagnetic conversion characteristics.
A narrow particle size distribution is preferred. Also improve durability
In combination with abrasives with different particle sizes as needed
Even with a single abrasive, the same effect can be achieved by widening the particle size distribution.
It can also be given. Tap density is 0.3-2g
/ Ml, water content 0.1-5%, pH 2-11, S
_BET1-30m²/ G is preferred. Used in the present invention
The shape of the abrasive can be acicular, spherical, or dice
Good, but those with corners in the shape are highly abrasive and are preferred
Good. Specifically, those described in WO98 / 35345
Among them, diamond is used as described above
This is effective in improving running durability and electromagnetic conversion characteristics.
Of course, the particle size and amount of the abrasive added to the magnetic and nonmagnetic layers
It should be set to the optimum value. [Additive] Used in the magnetic layer and nonmagnetic layer of the present invention.
Additives used include lubrication effect, antistatic effect,
Those with a scattering effect, plastic effect, etc. are used and combined
By doing so, overall performance can be improved. Lubrication effect
It is generated when the surfaces of materials are rubbed.
A lubricant is used which has a significant effect on adhesion. For lubricant
There are two types. The moisture used for magnetic recording media
Determine whether the lubricant is fully fluid or boundary lubricated
Can not, but if it is classified by general concept, it shows fluid lubrication
Higher fatty acid ester, liquid paraffin, silicone derivative
Long-chain fatty acids that show body lubrication and boundary lubrication, fluorine-based surface activity
And fluorinated polymers. With coated media
The lubricant is dissolved in the binder or partly hexagonal
It exists in an adsorbed state on the surface of the cerite magnetic powder
Yes, the lubricant moves to the surface of the magnetic layer.
The speed depends on the compatibility of the binder and lubricant.
The When the binder and lubricant are highly compatible, the migration rate is
It is faster when it is small and has low compatibility. Compatibility
As a way of thinking about the dissolution parameters of both
There is a comparison. Non-polar lubricants are effective for fluid lubrication,
A polar lubricant is effective for boundary lubrication. In the present invention, these fluids having different characteristics are used.
Higher fatty acid esters showing lubrication and long chain fats showing boundary lubrication
Preferably in combination with fatty acids, at least 3
It is more preferable to combine them. Combined with these
Solid lubricants can also be used. As a solid lubricant
For example, molybdenum disulfide, tungsten disulfide,
Lafite, boron nitride, graphite fluoride, etc. are used
The As long chain fatty acid showing boundary lubrication, carbon number 10 to 10
24 monobasic fatty acids (including unsaturated bonds,
And any of these metal salts.
(Li, Na, K, Cu, etc.). Fluorine
As surfactants and fluorine-containing polymers, fluorine-containing silica
Cone, fluorine-containing alcohol, fluorine-containing ester,
Fluorine-containing alkyl sulfate and its alkali gold
Examples include genus salts. Higher fatty acid ester showing fluid lubrication
Tellurium includes monobasic fatty acids having 10 to 24 carbon atoms.
It may contain saturated bonds or be branched)
And monovalent, bivalent, trivalent, tetravalent, pentavalent, and six carbon atoms
Any one of the monohydric alcohols (including unsaturated bonds,
It may also be branched)
Ester or difatty acid ester or trifatty acid ester
And monoalkyl ethers of alkylene oxide polymers
And fatty acid esters of ru. In addition, the flow
And dialkylpolysiloxanes as silicone derivatives
Loxane (alkyl has 1 to 5 carbon atoms), dialkoxy
Polysiloxane (alkoxy has 1 to 4 carbon atoms), mono
Alkyl monoalkoxypolysiloxane (alkyl is charcoal)
Prime number 1-5, alkoxy is carbon number 1-4), Feni
Polypolysiloxane, fluoroalkylpolysiloxane (A
Silicone oil, poles, etc.
Silicone having a functional group, fatty acid-modified silicone, fluorine
Examples thereof include silicon. Other lubricants having 12 to 22 carbon atoms
Monovalent, divalent, trivalent, tetravalent, pentavalent, hexavalent alcohol
Including union or branching)
C12-22 alkoxy alcohol (unsaturated bond)
May be included or branched), fluorine
Alcohol such as containing alcohol, polyethylene wack
Polyolefins such as polypropylene and polypropylene, ethylene
Polyg such as recall and polyethylene oxide wax
Recall, alkyl phosphate ester and its alkali gold
Metal salts, alkyl sulfates and their alkali metals
Salt, polyphenyl ether, fatty acid ester having 8 to 22 carbon atoms
And aliphatic amines having 8 to 22 carbon atoms.
The Antistatic effect, dispersion effect, plasticity effect, etc.
As shown, phenylphosphonic acid, specifically Nissan
Such as “PPA” of Gakaku Co., Ltd., α-naphthyl phosphate, phenyl
Ruphosphoric acid, diphenylphosphoric acid, p-ethylbenzenephosphone
Acid, phenylphosphinic acid, aminoquinones, various sila
Coupling agent, titanium coupling agent, fluorine-containing
Alkyl sulfates and alkali metal salts thereof, etc.
Can be used. The lubricant used in the present invention is particularly a fat.
Fatty acids and fatty acid esters are preferred, specifically WO 98
/ 35345 are mentioned. In addition to these
Different lubricants and additives can be used in combination.
it can. Further, alkylene oxide type, glycerin
-Based, glycidol-based, alkylphenol ethylene
Nonionic surfactants such as oxide adducts, cyclic amino acids, etc.
, Ester amide, quaternary ammonium salts, hydan
Toin derivatives, heterocycles, phosphonium or sulfoni
Cationic surfactants such as ums, carboxylic acids, sulfur
Ionic acid, phosphoric acid, sulfate ester group, phosphate ester group, etc.
Anionic surfactants containing amino acid groups, amino acids, amino acids
Nosulfonic acids, amino alcohol sulfuric acid or phosphoric acid
Stealth, alkylbedine type amphoteric surfactants, etc.
Can also be used. For these surfactants, see "Interface
Detailed description in "Handbook of Activators"
It is. These lubricants, antistatic agents, etc. are not necessarily 1
00% not pure, isomers, unreacted substances,
It may contain impurities such as by-products, decomposition products, and oxides.
I don't know. These impurities are preferably 30% or less.
Preferably, it is 10% or less. The present invention relates to fatty acid esthetics.
As described in WO 98/35345
It is also preferable to use a combination of tellurium and diester.
Yes. The magnetic recording medium of the present invention, particularly a disk-shaped magnet
C of surface of magnetic layer of air recording medium by Auger electron spectroscopy
/ Fe peak ratio is preferably 5-100, particularly preferred
5 to 80. Measurement conditions for Auger electron spectroscopy
Is as follows. Equipment: PHI-660 type manufactured by Φ Measurement conditions: primary electron beam acceleration voltage 3KV Sample current 130nA 250 times magnification Inclination angle 30 ° Under the above conditions, the kinetic energy (Kinetic Energy)
rgy) integrating the range of 130-730 eV three times, carbon
Of KLL peak of iron and LMM peak of iron in differential form
Therefore, it is obtained by taking the ratio of C / Fe. On the other hand, the upper and lower layers of the magnetic recording medium of the present invention
The amount of lubricant contained in each layer is hexagonal ferrite.
For 100 parts by weight of light magnetic powder or non-magnetic inorganic powder
5-30 mass parts is preferable. These lubricants and interfaces used in the present invention
Activators are those that have different physical effects,
The type, amount, and combination of lubricants that produce a synergistic effect
The usage ratio should be optimally determined according to the purpose.
Use non-magnetic and magnetic layers with different melting points on the surface.
Esthetics with different boiling points, melting points, and polarities that control bleeding
Surfactant amount that controls bleeding to the surface
To improve the stability of the coating by adjusting the
Consider increasing the amount of addition in the intermediate layer to improve the lubrication effect.
Of course, it is not limited to the examples shown here.
Yes. Generally, the total amount of lubricant is hexagonal ferrite
0.1% by mass to 50% with respect to conductive powder or non-magnetic powder
The amount is selected in the range of% by weight, preferably 2 to 25% by weight. Also, all of the additives used in the present invention.
Or some of them in the manufacture of magnetic and non-magnetic paints
May be added in the process, for example, before the kneading process
Kneading with magnetic substance, binder and solvent
If added in the process, if added in the dispersion process, after dispersion
In some cases, it may be added immediately before coating.
Depending on the purpose, a magnetic layer may be applied and then simultaneously or sequentially.
By applying some or all of the additives in the next application
Objectives may be achieved. Depending on the purpose,
After calendering or after slitting, the magnetic layer surface
A lubricant can also be applied to the surface. [Layer Structure] The thickness structure of the magnetic recording medium of the present invention.
The substrate is usually 2-100 μm, preferably 2-8.
0 μm. The support of the computer tape is 3.
0 to 6.5 μm (preferably 3.0 to 6.0 μm,
Preferably, the thickness is in the range of 4.0 to 5.5 μm.
Is used. Support, preferably non-magnetic flexible support
To improve adhesion between the body and the nonmagnetic layer or magnetic layer
A coating layer may be provided. The thickness of the undercoat layer is 0.01
~ 0.5μm, preferably 0.02-0.5μm
The Magnetic to produce effects such as antistatic and curl correction
A back layer is provided on the support opposite to the side where the layer is provided.
It does not matter. This thickness is usually 0.1-4 μm,
Preferably it is 0.3-2.0 micrometers. These primer
Known layers and back layers can be used. The thickness of the magnetic layer comprising the lower layer and the upper layer of the present invention
Is the saturation magnetization of the head used, head gap length, recording
Optimized by signal bandwidth, but preferably
Is 0.01 to 0.2 μm, more preferably 15 to 32 μm.
m. The thickness of the lower layer is usually 0.2 to 5.0 μm, preferably
Preferably 0.3 to 3.0 μm, more preferably 1.0.
~ 2.5 μm. The lower layer is substantially nonmagnetic.
If it is effective, for example, impurities and
Or intentionally containing a small amount of magnetic powder,
The configuration is substantially the same as that of the present invention.
Needless to say, it can be considered. Substantially
The nonmagnetic layer has a residual magnetic flux density of 10 mT or less or
Coercive force is less than 100 oersted (≒ 8kA / m)
Preferably with residual magnetic flux density and coercive force
Indicates no. If the lower layer contains magnetic powder,
It is preferable to contain less than 1/2 of the total inorganic powder. Also,
As a lower layer, soft magnetic powder and binder are included instead of the non-magnetic layer.
A soft magnetic layer may be formed. The thickness of the soft magnetic layer is
Same as layer. Further, a magnetic recording medium having two magnetic layers
In this case, a nonmagnetic layer or a soft magnetic layer may or may not be provided.
For example, the magnetic layer far from the support is 0.2 to 2 μm.
m, preferably 0.2 to 1.5 μm, close to the support
The outer magnetic layer can be 0.8 to 3 μm. Na
When it has a magnetic layer alone, it is usually 0.2-5μ.
m, preferably 0.5-3 μm, more preferably 0.
5 to 1.5 μm. [Back Layer] The magnetic recording medium of the present invention has a
A tack layer can be provided. Even magnetic disk back
Layers can be provided, but in general, computer data
Magnetic recording tapes are video tapes and audio tapes.
Compared to a loop, repeated running is strongly required. This
Back layer to maintain high running durability like
Contains carbon black and inorganic powder.
Are preferred. Carbon black has a different average particle size.
It is preferable to use two types in combination.
In this case, a particulate car having an average particle diameter of 10 to 20 nm.
Bon black and coarse particles with an average particle size of 230-300 nm
It is preferable to use a combination of child carbon black
Good. In general, the fine-particle carbon braid as described above
The surface electrical resistance of the back layer is set low by adding
In addition, the light transmittance can be set low. For magnetic recording device
Depending on the optical transmittance of the tape, it can be used for operation signals.
In such cases, there are many
The addition of fine carbon black is effective. Ma
Fine particulate carbon black generally retains liquid lubricant
Excellent power and contributes to reduction of friction coefficient when used with lubricant
The On the other hand, a coarse particle shape having an average particle size of 230 to 300 nm
Carbon black has a function as a solid lubricant.
In addition, a minute protrusion is formed on the surface of the back layer, and the contact surface
The product is reduced to contribute to the reduction of the friction coefficient. Fine particle carbon bra used in the present invention
Commercially available as black and coarse particulate carbon black
As a specific product, WO98 / 35
345 can be mentioned. Back layer
When using two types with different average particle sizes
10 to 20 nm particulate carbon black and 23
Content ratio of 0-300nm coarse carbon black
(Mass ratio) is the range of the former: latter = 98: 2-75: 25.
It is preferable that it is in the range, more preferably 95: 5 to
The range is 85:15. Carbon black in the back layer
(If two types are used, the total amount)
The amount is usually 30 to 80 with respect to 100 parts by mass of the binder.
In the range of parts by mass, preferably 45 to 65 parts by mass.
It is a range. Two kinds of inorganic powders having different hardnesses are used.
It is preferable to use together. Specifically, Mohs hardness 3
4.5 soft inorganic powder and Mohs hardness 5-9 hard inorganic powder
It is preferable to use powder. Mohs hardness of 3-4.
By adding 5 soft inorganic powder,
The friction coefficient can be stabilized. And this category
Due to the hardness of the enclosure, the sliding guide pole may not be cut off.
Yes. The average particle size of this inorganic powder is 30-50 nm.
It is preferable that it exists in the range. Mohs hardness of 3 to 4.5
Examples of soft inorganic powders include calcium sulfate and charcoal.
Calcium oxide, calcium silicate, barium sulfate, carbonate
Gnesium, zinc carbonate, and zinc oxide.
Yes. These can be used alone or in combination of two or more.
Can be used. Soft inorganic powder in the back layer
The content of is 1 with respect to 100 parts by mass of carbon black.
It is preferably in the range of 0 to 140 parts by mass, more preferably
Preferably, it is 35-100 mass parts. Add hard inorganic powder with Mohs hardness of 5-9
By doing so, the strength of the back layer is enhanced and the running durability
Improves. These inorganic powders are carbon black and
When used with the soft inorganic powder, it is suitable for repeated sliding.
Even so, there is little deterioration and it becomes a strong back layer. Also this nothing
Appropriate polishing force is given by adding machine powder, and the tape
The adhesion of shavings to the guide pole etc. is reduced. Especially soft
When used in combination with inorganic powder, the guide pole has a rough surface.
All the sliding characteristics are improved and the friction coefficient of the back layer is stabilized.
Can be planned. The average particle size of the hard inorganic powder is 80-
250 nm is preferable, and is in the range of 100 to 210 nm.
More preferably. Hard inorganic with Mohs hardness of 5-9
Examples of powders include α-iron oxide, α-alumina,
And chromium oxide (Cr₂O_Three). This
Each of these powders can be used alone or
May be used in combination. Among these, α-iron oxide or α
-Alumina is preferred. Hard inorganic powder content is
Usually 3 to 30 parts by weight per 100 parts by weight of bon black
Preferably, it is 3-20 mass parts. The soft inorganic powder and the hard inorganic powder are used for the back layer.
When using powder together, soft inorganic powder and hard inorganic powder
Hardness difference is 2 or more (more preferably 2.5 or more, special
3 or more) soft inorganic powder and hard inorganic powder
It is preferable to select and use. In the back layer,
Each of the different Mohs hardnesses having a specific average particle size
Two types of inorganic powders and two types with different average particle diameters
It is preferable to contain carbon black
Yes. The back layer may contain a lubricant.
it can. The lubricant may be the nonmagnetic layer or the magnetic layer described above.
As appropriate, select from the lubricants listed above.
Can be used. In the back layer, the lubricant is bonded
Usually added in the range of 1-5 parts by weight per 100 parts by weight of the agent
Is done. [Support] The support used in the present invention comprises:
Preferably it is a non-magnetic flexible support, the surface of the support
The heat shrinkage rate at 100 ° C. for 30 minutes is 0.5 for each direction.
%, And heat shrinkage at 80 ° C. for 30 minutes is 0.5% or less.
Lower, more preferably 0.2% or less
Yes. Furthermore, the heat shrinkage rate of the support at 100 ° C. for 30 minutes and
Thermal shrinkage at 80 ° C for 30 minutes in each direction within the surface of the support
On the other hand, it is preferable that the difference is within 10%. Support
Is preferably non-magnetic. These supports are polyester
Tylene terephthalate, polyethylene naphthalate, etc.
Polyesters, polyolefins, cellulose
Acetate, polycarbonate, aromatic or aliphatic poly
Amide, polyimide, polyamideimide, polysulfo
, Polyaramid, polybenzoxazole, etc.
Can be used. Polyethylene naphthalate,
It is preferable to use a high-strength support such as polyamide.
Yes. If necessary, change the surface roughness of the magnetic and base surfaces.
In order to obtain a laminated layer as disclosed in JP-A-3-224127.
A type of support can also be used. These supports
Pre-corona discharge treatment, plasma treatment, easy adhesion
You may perform a process, heat processing, a dust removal process, etc. Ma
Applying aluminum or glass substrate as a support of the present invention
It is also possible to do. In order to achieve the object of the present invention, a support is used.
Measured with a surface roughness meter TOPO-3D manufactured by WYKO.
The center surface average surface roughness Ra is 4.0 nm or less, preferably
It is necessary to use the one of 2.0 nm or less. these
The support is not just a small average surface roughness on the center plane.
In addition, it is preferable that there are no coarse protrusions of 0.5 μm or more.
The surface roughness shape is added to the support as necessary.
Freely controlled by the size and amount of filler
Is. An example of these fillers is C.
a, Si, Ti and other oxides, δ alumina and carbonate
Other examples include organic powders such as acrylic. Support
The maximum height Rmax is 1 μm or less, and the ten-point average roughness Rz is
0.5 μm or less, the center plane mountain height Rp is 0.5 μm or less,
The central plane valley depth Rv is 0.5 μm or less, and the central plane area ratio Sr
Is 10% or more and 90% or less, and the average wavelength λa is 5 μm or less.
Furthermore, it is preferably 300 μm or less. Desired electromagnetic conversion characteristics and
In order to obtain durability, the distribution of surface protrusions on these supports
Can be controlled arbitrarily by the
0.1mm each for the size of 01-1μm²Per
Can be controlled in the range of 0 to 2000
The The F-5 value of the support used in the present invention is good.
Preferably 5-50Kg / mm²(≒ 49-490MP
a) Also, the heat shrinkage rate of the support at 100 ° C. for 30 minutes is favorable.
Preferably 3% or less, more preferably 1.5% or less, 8
The heat shrinkage rate at 0 ° C. for 30 minutes is preferably 1% or less,
Preferably it is 0.5% or less. Breaking strength is 5-100
Kg / mm²(≈49-980 MPa), elastic modulus is 10
0 to 2000Kg / mm²(≒ 0.98 ~ 19.6GP
a) is preferred. The coefficient of thermal expansion is 10^-Four-10^-8/ ℃
Yes, preferably 10^-Five-10^-6/ ° C. Humidity expansion
The coefficient is 10^-Four/ RH% or less, preferably 10^-Five/
RH% or less. These thermal characteristics, dimensional characteristics, mechanical strength
The degree characteristics are within 10% of each direction in the surface of the support.
Are preferably equal. [Production Method] Magnetic Coating for Magnetic Recording Medium of the Present Invention
The process for producing at least the kneading process, the dispersing process,
And mixing steps provided as necessary before and after these steps
Consists of. Each process is divided into two or more stages
It does not matter. Magnetic powder used in the present invention, non-magnetic
Powder, binder, carbon black, abrasive, antistatic
All raw materials such as agents, lubricants and solvents
Or it may be added in the middle. In addition, individual raw materials
It may be divided and added in two or more steps. example
For example, kneading process of polyurethane, dispersion process, viscosity after dispersion
You may divide | segment and throw in in the mixing process for adjustment. Main departure
In order to achieve the clear objective, a conventional known manufacturing technique is used.
It can be used as part of the process. In the kneading process
-Open kneader, continuous kneader, pressure kneader, extruder
It is preferable to use the one with strong kneading power such as
Yes. When using a kneader, use magnetic powder or non-magnetic powder.
All or part of the binder (but 30% of all binders)
% Or more) and 15 parts per 100 parts of magnetic powder.
The kneading process is performed in the range of ˜500 parts. These kneading processes
For details of JP-A-1-106338, JP-A-1-106338.
79274. Magnetic layer solution and non-
Use glass beads to disperse the magnetic layer solution.
Yes, but zirconia bee is a high specific gravity dispersion medium
, Titania beads and steel beads are preferred. This
The particle size and filling rate of these dispersion media are optimized and used.
The A well-known thing can be used for a disperser. In the present invention, a magnetic recording medium having a multilayer structure is applied.
In this case, it is preferable to use the following method. First
First, a gravure coating commonly used in the application of magnetic paints
Cloth, roll coating, blade coating, extrusion coating
First, apply the lower layer with a cloth device, etc., and the lower layer is wet.
Japanese Patent Publication No. 1-46186 and JP-A-60-238
179, the support disclosed in JP-A-2-265672.
Apply the upper layer with body pressure type extrusion coating equipment
how to. Secondly, JP-A-63-88080 and JP-A-2-
17971, and disclosed in JP-A-2-265672.
One coating head that contains two slits for coating solution
A method in which the upper and lower layers are applied almost simultaneously using a lid. Third, special
The backup robot disclosed in Kaihei 2-174965
The upper and lower layers are removed by an extrusion coating device with a handle.
This is a method of applying at the same time. For aggregation of magnetic particles
To prevent deterioration of electromagnetic conversion characteristics of magnetic recording media
Therefore, JP-A-62-295174 and JP-A-1-236968.
The coating inside the coating head by a method as disclosed in
It is desirable to apply shear to the cloth fluid. Furthermore, application
The viscosity of the liquid is disclosed in JP-A-3-8471.
It is necessary to satisfy the numerical range. The configuration of the present invention is implemented.
To reveal, after applying and drying the lower layer, magnetic
Of course, even if you use sequential multilayer coating to provide a layer,
The effect of the invention is not lost. However, coating defects
To improve quality, such as dropouts
For this purpose, it is preferable to use the simultaneous multilayer coating described above. In the case of a disk, no orientation is used without using an orientation device.
However, a sufficiently isotropic orientation may be obtained.
Arrange the baltic magnets diagonally alternately, with solenoid
Using a known random orientation device, such as applying an alternating magnetic field
It is preferable. Hexagonal ferrite magnetic powder
Generally likely to be in-plane and vertical 3D random
However, in-plane two-dimensional randomization is also possible. Ma
Vertical alignment using a known method such as a magnet with different polarity
To give isotropic magnetic properties in the circumferential direction.
Yes. Vertical alignment is preferred especially for high density recording.
Yes. Moreover, it is good also as circumferential orientation using a spin coat. In the case of magnetic tape, a cobalt magnet or soreno
Oriented in the longitudinal direction using id. Dry wind temperature, wind
By controlling the amount and coating speed, the drying position of the coating film can be controlled.
It is preferable that the coating speed is 20 m / min.
1000m / min, the drying air temperature is preferably 60 ° C or higher.
Do proper pre-drying before entering the magnet zone.
You can also. As a calendering roll, epoxy,
Heat resistant such as imide, polyamide, polyimide amide
Treat with some plastic or metal roll
However, especially when using a double-sided magnetic layer, it is treated with metal rolls.
It is preferable to do. The treatment temperature is preferably 50 ° C. or less.
Furthermore, it is more preferably 100 ° C. or higher. Good line pressure
Preferably 200kg / cm (≒ 196kN / m) or more,
More preferably, 300 kg / cm (≈294 kN /
m) or more. [Physical characteristics] Magnetic recording medium according to the present invention
Has a residual magnetic flux density × magnetic layer thickness of 5 to 200 mT · μ.
m is preferred. Coercive force Hc is 1700-5000 els
Ted (≈136-400 kA / m) is preferred, 18
00-3500 oersted (≈144-280 kA /
m) is more preferred. Narrower coercive force distribution is preferred
SFD (switching field distribution)
And SFDr are preferably 0.7 or less. In the case of a magnetic disk, the squareness ratio (SQ) is 2.
In the case of dimensional randomness, it is usually 0.55 to 0.67.
Preferably 0.58-0.64 for 3D random
0.45 to 0.55 is preferred, and vertical for vertical alignment
Usually 0.6 or more in direction, preferably 0.7 or more, diamagnetic
When field correction is performed, usually 0.7 or more, preferably
0.8 or more. 2D random, 3D random
However, the orientation ratio is preferably 0.8 or more. Two-dimensional random
Vertical squareness, vertical Br and vertical direction
The direction Hc should be within 0.1 to 0.5 times the in-plane direction.
Is preferred. In the case of magnetic tape, the squareness ratio is 0.7 or more,
Preferably it is 0.8 or more. The magnetic recording medium of the present invention is worn against the head.
The friction coefficient is in the range of temperature -10 to 40 ° C and humidity 0 to 95%.
In general, the surface hardness is 0.5 or less, preferably 0.3 or less.
The resistance is preferably magnetic surface 10^Four-10¹²Ohm / s
q and the charging position are preferably -500V to + 500V. Magnetism
The elastic modulus at 0.5% elongation of the layer is preferably in each direction in the plane
100-2000Kg / mm²(≒ 980 ~ 19600
N / mm²), The breaking strength is preferably 10 to 70 kg /
mm²(≒ 98 ~ 686N / mm²), Bullets on magnetic recording media
The nature ratio is preferably 100 to 1500 kg / g in each direction in the plane.
mm²(≒ 980 ~ 14700N / mm²)
Preferably any temperature below 0.5% and below 100 ° C
The thermal contraction rate at is preferably 1% or less, more preferably
0.5% or less, most preferably 0.1% or less
The Glass transition temperature of magnetic layer (dynamic measured at 110 Hz
(Maximum point of loss elastic modulus in dynamic viscoelasticity measurement) is 50 ° C. or more and 12
0 ° C or less is preferable, and that of the lower layer is preferably 0 ° C to 100 ° C.
Good. Loss modulus is 1 × 10 ^Three~ 1x10^FourN / cm²
The loss tangent is preferably 0.2 or less.
Preferably there is. If the loss tangent is too large, adhesion failure
Is likely to occur. These thermal and mechanical properties are
It is preferable that each direction is substantially equal within 10%. Magnetism
The residual solvent contained in the active layer is preferably 100 mg / m
²Or less, more preferably 10 mg / m²It is as follows. Painting
The porosity of the fabric layer is preferably 30 volumes for both the lower layer and the upper layer.
The amount is not more than%, more preferably not more than 20% by volume. Sky
Smaller porosity is preferable to achieve high output,
Depending on the purpose, it may be better to secure a certain value.
For example, it is not available for disc media where repeated use is important.
Larger porosity is often preferred for running durability. The surface of the magnetic layer is a surface roughness meter manufactured by WYKO.
The center surface average surface roughness Ra measured by TOPO-3D is favorable.
Preferably it is 5.0 nm or less, more preferably 4.0 nm or less.
Below, it is particularly preferably 3.5 nm or less. The top of the magnetic layer
Large height Rmax is 0.5μm or less, and ten-point average roughness Rz is
0.3 μm or less, center plane mountain height Rp is 0.3 μm or less,
Center face valley depth Rv is 0.3 μm or less, center face area ratio Sr
Is 20% or more and 80% or less, and the average wavelength λa is 5 μm or less.
Furthermore, it is preferably 300 μm or less. The surface protrusion of the magnetic layer is
0.01 ~ 1μm size 0 ~ 2000 pieces
Can be set arbitrarily by the
It is preferable to optimize the conversion characteristics and the friction coefficient. this
Control surface properties and magnetic properties of the support filler.
Particle size and amount of powder added to the functional layer, calendering process
Can be easily controlled by the surface shape
The The curl is preferably within ± 3 mm. Main departure
A bright magnetic recording medium has a lower layer and an upper layer depending on the purpose.
It is easily estimated that the physical properties can be changed.
It is. For example, increase the elastic modulus of the upper layer to improve running durability
At the same time, the lower layer modulus of elasticity is lower than that of the upper layer.
For example, the contact of the air recording medium with the head is improved. [0069] The following examples further illustrate the present invention.
However, the present invention is not limited to this.
Yes. “Part” means “part by mass”. [0070] Example 1   Magnetic liquid formula 100 parts of barium ferrite powder (BF1: shown in Table 1) Binder resin         12 parts of vinyl chloride copolymer           (-SO_Three1 × 10 K group^-Foureq / g content, degree of polymerization: 300)         Polyester polyurethane resin 4 parts           (Neopentyl glycol / Caprolactone polyol / MDI             = 0.9 / 2.6 / 1, -SO_ThreeNa group: 1 × 10^-FourContains eq / g ) Phenylphosphonic acid 3 parts δ Alumina 1 (shown in Table 2) 1 part Carbon black (average particle size: 30 nm) 5 parts Butyl stearate 2 parts Stearic acid 3 parts 125 parts of methyl ethyl ketone 125 parts of cyclohexanone [0071] Non-magnetic liquid formulation 80 parts of acicular hematite                 (S_BET: 55m²/ G,                   Average long axis length: 0.10 μm, average needle ratio: 7,                   pH: 8.8, aluminum treatment: Al₂O_ThreeAs 1% by mass) 20 parts of carbon black                 (Average particle size: 17 nm,                   DBP and oil amount: 80 ml / 100 g,                   S_BET: 240m²/ G, pH 7.5) Binder resin         12 parts of vinyl chloride copolymer           (-SO_Three1 × 10 K group^-Foureq / g content, degree of polymerization: 300)         Polyester polyurethane resin 5 parts           (Neopentyl glycol / Caprolactone polyol / MDI             = 0.9 / 2.6 / 1, -SO_ThreeNa group: 1 × 10^-FourContains eq / g ) Phenylphosphonic acid 3 parts Butyl stearate 3 parts Stearic acid 3 parts 280 parts of 1: 1 mixed solvent of methyl ethyl ketone and cyclohexanone Those of the above magnetic liquid formulation and non-magnetic liquid formulation
For each, powder, polyvinyl chloride, phenylphos
Mix phonic acid and 50% by weight of each solvent in a kneader.
After kneading, add polyurethane resin and the remaining ingredients
Dispersed with a dog grinder. In the resulting dispersion,
Add 15 parts of anoate to non-magnetic liquid and 14 parts to magnetic liquid.
And add 30 parts of cyclohexanone to each
Filtered using a filter having an average pore size of 1 μm,
Coating liquid for nonmagnetic layer formation and magnetic layer formation respectively
Prepared. <Preparation of tape> For the obtained lower non-magnetic layer
Polyethylene terephthalate support with a thickness of 7μm
Apply on the holder so that the thickness after drying is 1.5μm.
Immediately thereafter, the coating layer for the lower nonmagnetic layer is still wet.
By controlling the application amount of the magnetic liquid formulation while
Wet simultaneous multilayer coating is applied to achieve a predetermined magnetic layer thickness.
Pass through the orientation device while both layers are still wet.
And longitudinally oriented. The oriented magnet at this time is a rare earth magnet (surface
Solenoid magnet (magnetic flux) after passing magnetic flux 500mT
The density is 500 mT) and the orientation is within the solenoid.
Dry to the extent that it does not return, then dry the magnetic layer and wind it up
It was. After that, a seven-stage calendar composed of metal rolls
Apply a calendar process at a roll temperature of 90 ° C, and
A web-shaped magnetic recording medium is obtained, and is slipped to a width of 8 mm.
8mm videotape samples were made. Example 2 Other than changing δ alumina 1 of magnetic layer to δ alumina 2
Produced a magnetic recording medium in the same manner as in Example 1. Comparative Example 1 Change δ alumina 1 of magnetic layer to α alumina (described in Table 2).
In addition, Example 1 except that the addition amount was changed to 2 parts
A magnetic recording medium was prepared in the same manner as described above. The obtained sample uses a vibrating sample magnetometer.
Magnetic properties were measured. Furthermore, the surface roughness of the sample,
The electromagnetic conversion characteristics were measured and are shown in Table 3. <Evaluation of Tape> The measurement method of electromagnetic conversion characteristics is as follows:
According to the following method. MI on 8 mm deck for data recording
G head (head gap 0.2 μm, track width 17
μm, saturation magnetic flux density 1.5T, azimuth angle 20 °)
Raw MR head (SAL bias, MR element is Fe-N
i, track width 6μm, gap length 0.2μm, ajma
Equipped with an angle of 20 °). Using the MIG head,
The relative speed of the head and head is 10.2 m / sec, 1 / 2T
b (λ = 0.5μm) The optimum recording current from the input / output characteristics
The signal was recorded with this current and reproduced by the MR head.
C / N is from the peak of the regenerative carrier to the demagnetization noise.
The resolution bandwidth of the spectrum analyzer is 100
It was set to kHz. Expressed as characteristics of the tape of Comparative Example 1
It was. The surface roughness was measured by WYKO (US Arizona).
State) optical interference three-dimensional roughness meter "TOPO-3D" is used
A sample area of 250 μm square was measured. For calculation of measured values
When doing so, make corrections such as tilt correction, spherical correction, and cylinder correction.
Implemented in accordance with JIS-B601, center plane average roughness Ra
Was the surface roughness value. The magnetic characteristics are vibration sample type magnetometer (Toei Industry Co., Ltd.)
) And an external magnetic field of 10 kOe (≒ 800 kA / m)
[Oe = {1 / (4π)} kA / m], parallel to the alignment direction
Measured. [0079] [Table 1] [0080] [Table 2] [0081] [Table 3] [0082] The present invention provides a binder with a ferromagnetic powder on a support.
In a magnetic recording medium provided with a magnetic layer dispersed therein
Preferably, the thickness of the magnetic layer is 0.2 μm or less, and
Δ aluminum having an average particle size of 5 to 100 nm in the magnetic layer
By adding nano-particulates, its electromagnetic conversion characteristics
Noise and C / N can be improved.

Claims (1)

1. A magnetic recording medium comprising a magnetic layer containing at least a ferromagnetic powder on a support, the magnetic recording medium comprising δ alumina powder.