JP2003085733A - Magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic recording medium having excellent traveling durability, such as still durability. SOLUTION: This magnetic recording medium is a magnetic recording medium provided with a magnetic layer containing at least ferromagnetic powder and a binder on a base, in which the coating application layer contains a fatty acid ester and the thickness of the fatty acid ester layer existing on the surface of the coating application layer is 2 to 20 Å.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a magnetic recording medium provided with a coating layer containing powder and a binder.
Is. [0002] In general, a coating material using a binder has characteristics.
Stabilizers, antioxidants, plasticizers, lubricants, boundaries for improvement
Various additives such as surfactants are blended. Especially applied
Magnetic layer and non-magnetic layer to improve the characteristics of magnetic recording media
The higher fatty acid ester is a lubricant for imparting slidability.
Tell and fatty acids are blended. These compounds are characteristic
The amount of additive present on the surface is the most characteristic
It is considered to correlate with Especially for coated magnetic recording media
It is known to have a great influence on sliding characteristics. This
The surface amount of these additives depends on the manufacturing method, use or storage.
It will change. When developing magnetic recording media
Change the process conditions such as the amount of addition and drying.
A recording medium is prepared and the amount of ester on the magnetic layer surface is unknown.
In addition, the driving characteristics were evaluated to determine the direction of development. Near
Auger spectroscopy (AES) for coated magnetic recording media
Or magnetic photoelectron spectroscopy (ESCA), etc.
Fatty acid on the surface as the ratio of C to organic matter (C / Fe)
It became possible to determine the amount of ester. This technique
Very simple and effective as an index of surface lubricant
Has been. However, measurement by AES or ESCA
Then, it is limited to the measurement in a vacuum. Introduce sample into vacuum
Then fatty acid esters are volatile, so in a vacuum
It vaporizes and scatters, and C / Fe decreases rapidly. So AE
For actual measurement with S or ESCA, vacuum the sample.
An experienced operator takes measurements within a certain period of time after installation.
Is doing. But even if you do that
In AES and ESCA, there is no difference in volatility due to compounds.
Uniformly evaluate things that cannot be seen and that have significantly different molecular weights
It is not possible. C obtained by AES or ESCA
/ Fe is a relative indicator and the fat present on the actual surface
The absolute amount of fatty acid ester cannot be determined. Jun
In most cases, several types of lubricants are blended, but C / Fe
In the parameter by elemental analysis that is compounded that
It is not possible to know the surface amount for each lubricant.
In addition, since we are looking at Fe and C, the seeds of magnetic material and binder
If there is a difference in type or quantity, there is a problem that comparison is not possible
The Also, it is essentially a relative value and actually correlates with driving characteristics.
Fatty acid ester present on the surface of the magnetic layer
Of fatty acids that are thought to correlate with the amount of
The thickness of the tell layer cannot be known. It is possible to separate and detect fatty acid esters in the magnetic layer.
As a mechanochemical separation method, an extraction method using an organic solvent is used.
In general, contact with organic solvents for a short time
The organic solvent penetrates into the inside, and the fatty acid beauty treatment only on the surface of the magnetic layer.
You cannot ask for it. Therefore, the inventor applied the coating layer surface.
Of fatty acid ester present on the surface of a magnetic layer
As a method, a transcription method was developed (Application No. 2000-303).
942). This method is determined at atmospheric pressure instead of vacuum
Individual fatty acids formulated in the environment you want to know
The value can be obtained for ester, and as an evaluation method
used. However, this technique uses transcription.
Therefore, the molecular weight of each fatty acid ester is transferred to the transfer medium.
Affects the ease of use, and not only the surface layer but also the transfer time
If the length is increased, the fatty acid ester present inside is also transcribed.
Is strictly seeking fatty acid esters present in the surface layer
However, it was a relative value. Accordingly, the fatty acid ester present in the surface layer of the magnetic layer.
It has never been possible to accurately determine the amount of tella
To improve the running durability of magnetic recording media, especially the still durability
Fatty acid beauty salon present on the surface of the magnetic layer that can be improved
I didn't know how much. [0005] The present invention is still durable.
To provide a magnetic recording medium excellent in running durability such as durability
Is an issue. [0006] The inventor has formulated a coating layer.
As a result of earnest research on the hydrolysis reaction of the fatty acid ester,
Fatty acid ester present on the surface of the coating layer containing the ferromagnetic powder
AES and transcription methods for separating and quantifying stealth
An entirely separate quantification technique was invented. This technique
The fatty acid ester present in the coating layer surface layer and the coating layer
Determine the reaction rate of fatty acid esters present in solution.
Therefore, the coating layer surface, which was impossible to analyze with the conventional method,
The amount of fatty acid ester in the layer and the thickness of the fatty acid ester layer
It is possible to ask. The present invention provides the above fat
Running durability by applying acid ester determination method
The fat that should be present on the surface of the coating layer, the most effective for improving
The thickness of the fatty acid ester layer is specified. That is, book
The invention provides at least a ferromagnetic powder and a binder on a support.
In a magnetic recording medium provided with a coating layer having a magnetic layer
The coating layer contains a fatty acid ester and is present on the coating layer surface.
The thickness of the existing fatty acid ester layer is 2 to 20 mm
A magnetic recording medium characterized by the above. Preferred mode of the present invention
Is as follows. (1) The coating layer is a nonmagnetic layer provided between the magnetic layer and the support.
Alternatively, the above magnetic recording having a multilayer structure composed of soft magnetic layers
Medium (2) Ferromagnetic powder is ferromagnetic metal powder or hexagonal
The magnetic recording medium is a ferrite powder. DETAILED DESCRIPTION OF THE INVENTION
The thickness of the fatty acid ester layer to be present on the layer surface is 2 to 2.
It is specified as 20cm, preferably 2-10cm.
The thickness of the fatty acid ester layer is out of the range of 2 to 20 mm
Both smaller than 2mm and larger than 20mm
Running durability is not improved. In the present invention, this fat
The thickness of the acid ester layer is determined by the following method.
Means. First, the amount of fatty acid ester on the surface of the coating layer
A method of obtaining will be described with reference to FIG. In the vertical axis, ln (a ₀ /
a _t ), Plotting time on the horizontal axis
The slope of the straight line b plotted over time and the straight line a
An intersection d with a straight line c with a smaller slope is obtained, and the intersection t1 is obtained.
The amount of fatty acid ester attenuated over time (a ₀ -A _t1 )
The amount of fatty acid ester present in the surface layer of the coating layer. And
The remaining amount a at the intersection in FIG. _t1 Is the fatty acid group inside the coating layer.
Stealth amount. Where a ₀ Is the initial fatty acid ester
Quantity, a _t Indicates the amount of residual fatty acid ester after t hours.
I will show you. a ₀ Sample (coating layer or coating with it)
Coating layer immediately after forming the coating layer before storing a certain amount)
It means the amount of fatty acid ester in the body. a _t The sample is constant
Residual fatty acid in the sample when stored in a temperature and humidity environment for t hours
The amount of ester. Fatty acid ester amount a ₀ And a _t Measurement
The method is not particularly limited, but the sample should be
Extract, GC (gas chromatography) or HP
Highly sensitive analysis such as LC (High Performance Liquid Chromatography)
Means are mentioned. Where fatty acid esters are used together
In the case of individual fatty acid esters. When saving
For samples with different intervals t, fatty acid esters before and after storage
By comparing the amounts, the reaction rate, ie straight lines b and c
Ask for. When storing under temperature and humidity conditions,
Care must be taken to prevent volatilization of tella. Temperature and humidity
The condition is the hydrolyzability of the fatty acid ester to be analyzed.
Or if the fatty acid ester hydrolyzability is unknown
Depending on the temperature and humidity you want to know,
Can be selected. However, low temperature and low humidity
However, it is necessary to lengthen the retention period in order to know the necessary changes.
There is. As the fatty acid ester used in the present invention
Is not particularly limited, but has 10 to 10 carbon atoms.
24 monobasic fatty acids (including unsaturated bonds,
And monovalent, 2 to 22 carbon atoms.
One of trivalent, trivalent, tetravalent, pentavalent and hexavalent alcohol
(It does not matter whether it contains unsaturated bonds or is branched.
Mono-fatty acid ester or di-fatty acid ester
And tellurium or trifatty acid esters. concrete
Butyl stearate, octyl stearate,
Mil stearate, isooctyl stearate, butyl
Myristate, octyl myristate, butoxyethyl
Stearate, diethylene glycol monobutyl ether
Rustearate, 2-ethylhexyl stearate, 2
-Octyl dodecyl palmitate, 2-hexyl deci
Lupalmitate, isohexadecyl stearate, ole
Iloleate, dodecyl stearate, tridecyl
Tearate, oleyl erucate, neopentylglyco
Rudidecanoate, ethylene glycol dioleyl, etc.
Can be mentioned. Fatty acid ester and ferromagnetic powder
It may be added to a coating solution consisting of a binder, or a magnetic layer may be applied.
You may overcoat after cloth. Hereinafter, the magnetism of the present invention
The components of the recording medium will be described. [Magnetic layer] The magnetic layer is composed of two or more layers even if it is a single layer.
In the latter case, the positional relationship between these layers
Even if they are adjacent to each other, a layer other than the magnetic layer is interposed between them.
A known layer structure can be adopted. The coating layer of the magnetic recording medium of the present invention is preferably
Or mainly non-magnetic powder and binder between the support and the magnetic layer.
A nonmagnetic layer (also referred to as a lower layer) is provided. Magnetic layer
Examples of a multilayer structure include ferromagnetic iron oxide and ferromagnetic core
Baltic modified iron oxide, CrO ₂ Powder, hexagonal ferrite
Ferromagnetic powder selected from powder and various ferromagnetic metal powders
And a combination of magnetic layers dispersed in a binder.
It is done. In this case, the same kind of ferromagnetic powder
Also contains different ferromagnetic powders with different elemental compositions, powder sizes, etc.
A magnetic layer can also be combined. In the present invention
Contains ferromagnetic metal powder or hexagonal ferrite powder
Magnetic recording medium having nonmagnetic layer provided between magnetic layer and support
Is preferred. The magnetic recording medium having a multilayer structure includes a lower layer and a magnetic layer.
After applying the lower layer on the support, the upper layer is still wet.
Wet-on-wet application of layers simultaneously or sequentially
In the G method (W / W), the upper magnetic layer is removed after the lower layer is dried.
Can be created by the dry-on-wet method (W / D)
Yes. Simultaneous or sequential wet application is preferred in terms of production yield.
That's right. In the present invention, simultaneous or sequential wet application (W / W)
Since the upper layer / lower layer can be formed simultaneously, the calendar process
The surface treatment process such as
The surface roughness of the magnetic layer can be improved. (Ferromagnetic powder) Ferromagnetic powder used in the present invention
As a powder, ferromagnetic metal powder or hexagonal ferrite
A powder is preferred. As the ferromagnetic metal powder, α-Fe is used.
A ferromagnetic metal powder having a main component is preferred. Ferromagnetic metal powder
At the end, in addition to predetermined atoms, 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.
The Co content is preferably 1 atomic% to 40 atomic% with respect to Fe.
More preferably, 15 atomic% to 35 atomic%
More preferably, it is 20 atomic% to 35 atomic%. Noble such as Y
The content of earth elements is preferably 1.5 atomic% to 12 atomic%
More preferably, 3 atomic% to 10 atomic%, more preferably
Or 4 to 9 atom%. Al is 1.5 atomic%
~ 12 atomic% is preferred, more preferably 3 atomic% ~
10 atomic%, more preferably 4 atomic% to 9 atomic%
The The rare earth and Al containing Y function as a sintering inhibitor.
Higher anti-sintering effect when used in combination
Is obtained. These ferromagnetic powders are dispersed later.
Agent, lubricant, surfactant, antistatic agent, etc.
Pre-processing may be performed. 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. The BET method is used for the ferromagnetic powder of the magnetic layer of the present invention.
Specific surface area (S _BET ) 40-90m ² / G
Preferably 45-85m ² / G. 40m ² / G
Below, the noise becomes high, 90m ² Smooth above / g
A difficult surface is not preferable. Magnetism of the magnetic layer of the present invention
The crystallite size of the conductive powder is 80-180mm, which is preferable
Or 100-170 mm, more preferably 110-165.
It is a spear. The average major axis length of the ferromagnetic powder is 0.02 μm ~
0.20 μm, preferably 0.03 μm to 0.1
5 μm, more preferably 0.03 μm to 0.1
0 μm. Average acicular ratio of ferromagnetic powder ((major axis length / short
The average of the axial length) is preferably from 3 to 15, more preferably from 3 to 1.
0 is preferred. The saturation magnetization σs of magnetic metal powder is usually 9
0-170A ・ m ² / Kg, preferably 100-
160A ・ m ² / Kg, more preferably 110-160
Am ² / Kg. Ferromagnetic metal powder has a coercive force of 13
5 to 279 kA / m is preferable, and 143 is more preferable.
~ 239 kA / m. The moisture content of the ferromagnetic metal powder is 0.1 to 2 mass.
% Is preferable. The pH of the ferromagnetic powder is
It is preferable to optimize by a combination with a mixture.
The range is 6-12, preferably 7-11.
The SA (stearic acid) adsorption amount of ferromagnetic metal powder (table
The scale of the basic point of the surface is 1-15 μmol / m ² Preferred
Or 2 to 10 μmol / m ² , More preferably 3
8μmol / m ² It is. N soluble in ferromagnetic powder
a, Ca, Fe, Ni, Sr, NH _Four , SO _Four , Cl, N
O ₂ , NO _Three Inorganic ions such as these
Is preferably essentially absent. Total of each ion is 30
If it is about 0 ppm or less, the characteristics are not affected. Ma
The ferromagnetic powder used in the present invention has fewer holes.
Is preferably 20% by volume or less, more preferably
5% by volume or less. For the shape, the powder shown above
Needle shape, rice grain shape, spindle shape if body size and magnetic properties are satisfied
Either of them can be used. SFD of ferromagnetic powder itself (s
switching-fielddistributio
n) is preferably smaller and the Hc distribution of the ferromagnetic powder is smaller.
Need to be crushed. If the tape SFD is small, the magnetization
Sharp inversion, small peak shift, and high density
Suitable for digital magnetic recording. To reduce the Hc distribution
For the ferromagnetic metal powder, the particle size of goethite
Monodispersed α-Fe to improve cloth ₂ O _Three Use, between particles
There are methods such as preventing sintering. (Hexagonal ferrite powder) hexagonal ferrite
Barium ferrite, strontium Fe
Light, lead ferrite, calcium ferrite and this
There are various types of these substitution products, Co substitution products, and the like. Specifically
Is magnetoplumbite type barium ferrite and
Cover the particle surface with trontium ferrite and spinel.
Magnetoplumbite type ferrite, and some spines
Composite magnetoplumbite-type barium containing ruthenium phase
And ferrite and strontium ferrite
Other than the predetermined atoms, Al, Si, S, Nb, S
n, Ti, V, Cr, Cu, Y, Mo, Rh, Pd, A
g, Sn, Sb, Te, W, Re, Au, Bi, La,
Ce, Pr, Nd, P, Co, Mn, Zn, Ni, B,
It may also contain atoms such as Ge and Nb. In general
Co-Zn, Co-Ti, Co-Ti-Zr, Co-T
i-Zn, Ni-Ti-Zn, Nb-Zn-Co, Sn
-Elements such as Zn-Co, Sn-Co-Ti, and Nb-Zn
Can be used. According to raw materials and manufacturing method
Some contain specific impurities. Powder size
Is a hexagonal plate diameter, preferably an average plate diameter of 10 to 55 nm,
Is preferably 10 to 45 nm, particularly preferably 1
0 to 40 nm. When dispersing the magnetic material, the surface of the magnetic powder is separated.
Processing with a material suitable for the dispersion medium and polymer is also performed.
Yes. As the surface treatment agent, inorganic compounds and organic compounds are used.
The Main compounds include oxides such as Si, Al, P, etc.
Is hydroxide, various silane coupling agents, various titanium catalysts
A pulling agent is a typical example. (Carbon black used in the magnetic layer)
The magnetic layer of the present invention optionally contains carbon black.
be able to. Carbon black used is for rubber
Furnace, rubber thermal, color black, conductive
Carbon black, acetylene black, etc.
be able to. Specific surface area is 5-500m ² / G, DBP
Oil absorption is 10 to 400 ml / 100 g, average particle size is 5
nm to 300 nm, pH is 2 to 10, and water content is 0.1 to
10% by mass and tap density of 0.1-1 g / cc are preferred
That's right. Also, before adding carbon black to magnetic paint
It is preferable to disperse in advance with a binder. This
These carbon blacks can be used alone or in combination.
Can be used. When using carbon black
Is usually used in an amount of 0.1 to 30% by mass relative to the magnetic material.
Can. Carbon black is an antistatic material for the magnetic layer.
Functions such as stopping, reducing the coefficient of friction, providing light shielding, and improving film strength
These differ depending on the carbon black used.
The (Abrasive) Abrasive that can be used in the magnetic layer of the present invention.
As an abrasive, α-alumina having a conversion rate of 90% or more, β-
Alumina, fine diamond, silicon carbide, black oxide
, Cerium oxide, α-iron oxide, corundum, silicon nitride
Element, silicon carbide, titanium carbide, titanium oxide, dioxide
Silicon, boron nitride, etc.
Known materials are used alone or in combination. these
The powder size of the abrasive is preferably 0.01 to 1 μm.
In order to improve the electromagnetic conversion characteristics, the particle size distribution is narrow
Is preferred. Also, to improve durability, if necessary
You can combine abrasives with different powder sizes,
Abrasives can have the same effect by widening the particle size distribution.
Both are possible. Tap density is 0.3-1.5 g / c
c, moisture content is 0.1 to 5% by mass, pH is 2 to 11, ratio table
The area is 1-40m ² / G is preferred. Used in the present invention
The shape of the abrasive is acicular, spherical, or dice
However, those with corners in part of the shape are highly abrasive.
preferable. [Non-magnetic layer (lower layer)]
The detailed contents will be described. The lower layer is essentially non-magnetic
If there is no particular limitation, but preferably
Is a structure containing nonmagnetic powder and a binder. The lower layer is substantial
In addition, magnetic powder can be used as long as it is non-magnetic.
The If the lower layer is substantially non-magnetic, the electromagnetic conversion of the upper layer
The lower layer has magnetism as long as the characteristics are not substantially degraded.
It is to allow that. Non-magnetic powder used in the lower layer of the present invention
For example, metal oxide, hydrated metal oxide, metal carbonate
Selected from inorganic compounds such as salt, metal nitride, metal carbide, etc.
Can be selected. Examples of inorganic compounds include α
Α-alumina, β-alumina, γ-al with a rate of 90% or more
Mina, θ-alumina, silicon carbide, chromium oxide,
Lithium, α-iron oxide, goethite, silicon nitride, titanium dioxide
Tan, silicon dioxide, tin oxide, magnesium oxide, oxidation
Zirconium, zinc oxide, barium sulfate, etc.
Or used in combination. Particularly preferred is a particle size
Diacids due to the small distribution and many functions
Titanium fluoride, zinc oxide, α-iron oxide, gateite, sulfate
And more preferably titanium dioxide and α-acid.
Ferrous and gateite. Especially preferred is non-magnetic
The powder size of the powder is 0.01 μm to 0.5 μm.
Especially when the nonmagnetic powder is a granular metal oxide, the average
The particle diameter is preferably 0.08 μm or less, and is an acicular metal oxide.
In some cases, the average major axis length is preferably 0.3 μm or less,
More preferably, it is 0.2 μm or less. Tap density is usually
0.3 to 1.5 g / ml, preferably 0.4 to 1.3 g
/ Ml. The water content of the non-magnetic powder is usually 0.2 to 5
% By weight, preferably 0.3-3% by weight, more preferably
0.3 to 1.5% by mass. The pH of the non-magnetic powder is
Usually it is 3-12, but the pH is particularly between 5.5-11.
preferable. The specific surface area of non-magnetic powder is usually 1-100m
² / G, preferably 5 to 80 m ² / G, more preferably 1
0-80m ² / G. The crystallite size of non-magnetic powder is
40-1000cm is preferable, 40-800cm 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 1.5-7, preferably
3-6. Shape is acicular, spherical, polyhedral, plate-like
Misalignment is acceptable. SA (stearic acid) adsorption of non-magnetic powder
The amount is usually 1-20 μmol / m ² , Preferably 2-1
5 μmol / m ² And more preferably 3 to 8 μmol /
m ² It is. Use non-magnetic powder with high stearic acid adsorption
When using the magnet, the surface is modified with organic substances that strongly adsorb to the surface.
It is preferable to create an air recording medium. These non-magnetic
On the surface of the powder, Al, Mg, Si, Ti, Zr, Sn,
Surface treatment with Sb, Zn and Y compounds is preferred.
Particularly preferred for dispersibility is Al. ₂ O _Three , SiO ₂ , Ti
O ₂ , ZrO ₂ MgO and their hydrated oxides
More preferred is Al ₂ O _Three , SiO ₂ , ZrO ₂ And
And these hydrated oxides. Known by mixing carbon black in the lower layer
Lowering the surface electrical resistance Rs, which is the effect of
To achieve the desired micro Vickers hardness
You can In addition, carbon black should be included in the lower layer.
It is also possible to bring about the effect of storing the lubricant
The Carbon black types are rubber fan and rubber.
Thermal, color black, conductive carbon black
And acetylene black can be used. Underlayer
Depending on the desired effect,
Such characteristics should be optimized and more effective when used in combination.
Fruit may be obtained. Ratio of lower layer carbon black
Surface area is usually 50-500m ² / G, preferably 70
~ 400m ² / G, DBP oil absorption is usually 20-400
ml / 100g, preferably 30-400ml / 100
g. The average particle size of carbon black is usually 5 to
80 nm, preferably 10-50 nm, more preferably
10-40 nm. Carbon black has a pH of 2
10, the water content is 0.1 to 10% by mass, and the tap density is 0.00.
1-1 g / ml is preferred. Carbon black for paint
It can be dispersed with a binder before addition.
Yes. These carbon blacks are the above inorganic compound powders
Of the total mass of the non-magnetic layer within a range not exceeding 50% by mass
It can be used within a range not exceeding 40% by mass. These cars
Bon black should be used alone or in combination
Can do. 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. Lower layer binder resin (type and amount), lubricant,
Regarding the amount, type, solvent, and dispersion method of dispersants and additives
Known techniques relating to the magnetic layer can be applied. [Binder] Magnetic layer of the magnetic recording medium of the present invention
As a binder used for the lower layer and the like, conventionally known heat
Plastic resin, thermosetting resin, reactive resin and mixtures of these
Things are used. Thermoplastic resins include glass transition temperatures
Degree is −100 to 150 ° C., number average molecular weight is 1,000 to
200,000, preferably 10,000-100,0
00, the degree of polymerization is about 50-1000. This
Examples include vinyl chloride, vinyl acetate, vinyl
Alcohol, maleic acid, acrylic acid, acrylic acid ester
Tellurium, vinylidene chloride, acrylonitrile, methacryl
Acid, methacrylate ester, styrene, butadiene,
Tylene, vinyl butyral, vinyl acetal, vinyl
Polymer or copolymer containing ether, etc. as a structural unit
Body, polyurethane resin, and various rubber resins. Also,
As a thermosetting resin or reactive resin, phenol resin is used.
Fat, epoxy resin, polyurethane curable resin, urea resin
Fat, melamine resin, alkyd resin, acrylic reaction tree
Fat, formaldehyde resin, silicone resin, epoxy
-Polyamide resin, polyester resin and isocyanate
Prepolymer mixture, polyester polyol and poly
Isocyanate mixture, polyurethane and polyisocyanate
And a mixture of nates. About these resins
Details on “Plastic Handbook” published by Asakura Shoten
It is described in. In addition, each known electron beam curable resin
It can also be used for layers. These examples and their manufacture
The method is described in detail in JP-A-62-256219.
Has been. These resins can be used alone or in combination
However, preferred are vinyl chloride resin and vinyl chloride.
Vinyl acetate copolymer, vinyl chloride vinyl acetate vinyl vinyl
Coal copolymer, vinyl chloride, vinyl acetate, maleic anhydride
A copolymer and at least one selected from polyurethane
Combinations of resins, or polyisocyanates
A combination of these. 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 binder used in the nonmagnetic layer and magnetic layer of the present invention.
The mixture is usually 5-50 with respect to the non-magnetic powder or magnetic substance.
Used in the range of mass%, preferably in the range of 10-30 mass%
I can. 5-30 quality when using vinyl chloride resin
2% by mass when using polyurethane resin
%, Polyisocyanate in the range of 2-20% by mass
Are preferably used in combination.
If head corrosion occurs due to the amount of dechlorination,
Use only tan or polyurethane and isocyanate only
It is also possible to use. In the present invention, polyureta
When glass is used, the glass transition temperature is usually -50 to 15
0 ° C, preferably 0-100 ° C, elongation at break of 100-2
000%, breaking stress is 0.49 to 98 MPa, yield point is
0.49 to 98 MPa is preferable. The magnetic recording medium of the present invention preferably has two or more layers.
From the top. Therefore, the amount of the binder, the chloride occupying in the binder
Vinyl resin, polyurethane resin, polyisocyanate
Or other resin amount, each of which forms the magnetic layer
Resin molecular weight, polar group weight, or the aforementioned resin
Of course, the physical properties can be changed for each layer as needed.
Should be optimized in each layer, rather than multilayer magnetic
A known technique relating to the adhesive layer can be applied. For example, in each layer
Reduce the scratches on the surface of the magnetic layer when changing the amount of inder
For this purpose, it is effective to increase the amount of binder in the magnetic layer.
Yes, to improve the head touch to the head
Increase the amount of binder in the nonmagnetic layer to make it flexible.
Can. As the polyisocyanate used in the present invention,
Is tolylene diisocyanate, 4,4'-diphenyl
Methane diisocyanate, hexamethylene diisocyanate
, Xylylene diisocyanate, naphthylene-1,
5-diisocyanate, o-toluidine diisocyanate
, Isophorone diisocyanate, triphenylmethane
Isocyanates such as triisocyanate and the like
Products of these isocyanates and polyalcohols
Polyisocyanate formed by condensation of isocyanates
Cyanate and the like can be used. [Additive] For the magnetic layer, nonmagnetic layer, etc. of the present invention.
Additives used include lubrication effect, antistatic effect,
Those having a dispersion effect, a plastic effect, etc. are used. Disulfur
Molybdenum, tungsten disulfide, graphite, nitrogen
Boron fluoride, graphite fluoride, silicone oil, polar groups
Silicone, fatty acid-modified silicone, fluorine-containing silicone
Corn, fluorine-containing alcohol, fluorine-containing ester,
Polyolefin, polyglycol, alkyl phosphate ester
And its alkali metal salts, alkyl sulfates
And its alkali metal salts, polyphenyl ether,
Nylphosphonic acid, α-naphthyl phosphoric acid, phenyl phosphoric acid, diph
Phenyl phosphoric acid, p-ethylbenzenephosphonic acid, phenyl
Phosphinic acid, aminoquinones, various silane couplings
Agent, titanium coupling agent, fluorine-containing alkyl sulfate
Esters and alkali metal salts thereof, C10-24
Monobasic fatty acids (including unsaturated bonds, also branched
And any of these metal salts (Li,
Na, K, Cu, etc.) or one having 12 to 22 carbon atoms
, Divalent, trivalent, tetravalent, pentavalent, hexavalent alcohol (unsaturated
May contain bonds or branch)), charcoal
Alkoxy alcohol having a prime number of 12 to 22 (unsaturated bond
It may be included or branched), Archile
Fatty acid ester of monoalkyl ether of oxide polymer
Tell, fatty acid amide having 8 to 22 carbon atoms, 8 to 22 carbon atoms
Aliphatic amines, etc. can be used. Specific examples of these include fatty acids and caps.
Phosphoric acid, caprylic acid, lauric acid, myristic acid, pal
Mytic acid, stearic acid, behenic acid, oleic acid, ella
Idic acid, linoleic acid, linolenic acid, isostearin
Acid, and the like. For alcohols, oleyl al
Coal, stearyl alcohol, lauryl alcohol,
Etc. In addition, alkylene oxide,
Lysine, glycidyl, alkylphenol
Nonionic surfactants such as lenoxide adducts, cyclic
Amines, ester amides, quaternary ammonium salts,
Dantoin derivatives, heterocycles, phosphonium or sulfur
Cationic surfactants such as phoniums, carboxylic acids,
Sulfonic acid, phosphoric acid, sulfate ester group, phosphate ester
Anionic surfactants and amino acids containing acidic groups such as
, Aminosulfonic acids, amino alcohol sulfuric acid or
Is an amphoteric interface such as phosphate esters, alkylbedine type, etc.
An activator or the like can also be used. These lubricants, antistatic agents, etc.
Is not necessarily 100% pure, it is an isomer other than the main component
Body, unreacted materials, side reaction products, decomposition products, oxides, etc.
It may be included. These impurities are less than 30% by mass.
The lower is preferable, more preferably 10% by mass or less
The 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.
S with different boiling point, melting point and polarity to control bleeding
Surface activity that controls bleeding on the surface using tellurium
Lubrication that improves coating stability by adjusting the dosage
Do not increase the additive amount in the intermediate layer to improve the lubrication effect
Of course, it is limited to the example shown here.
There is no. Generally, the total amount of lubricant is magnetic or non-magnetic.
0.1% to 50% by weight, preferably
It is selected in the range of 2% by mass to 25% by mass. Also, all of the additives used in the present invention.
Or part of which process in the production of magnetic and non-magnetic coatings
May be added, for example, a magnetic material before the kneading step.
When mixing with a magnetic material, binder and solvent kneading process
When adding at the dispersion step, add at the dispersion step.
In some cases, it is added just before coating. Ma
Depending on the purpose, after applying the magnetic layer, simultaneously or sequentially
By applying some or all of the additive
The objective may be achieved. Depending on the purpose,
After rendering or after slitting, on the magnetic layer surface
A lubricant can also be applied. Used in the present invention
As the organic solvent, known ones can be used, for example, JP-A-6-68.
The solvent described in 453 can be used. [Layer structure] The thickness structure of the magnetic recording medium of the present invention.
For the composition, the support is preferably 2.5 to 8 μm, and the volume
In order to increase the density, more preferably 2.5-7.
It is 5 μm, particularly preferably 2.5 to 7 μm. Support
Undercoat for better adhesion between the nonmagnetic layer and magnetic layer
A layer may be provided. The thickness of the undercoat layer is 0.01 to
0.5 μm, preferably 0.02 to 0.5 μm.
These undercoat layers can be known ones. Magnet of the present invention
The thickness of the magnetic layer of the air recording medium is used when it has a lower layer.
Head saturation magnetization, head gap length, recording signal
Although optimized by the bandwidth, generally 0.0
5 μm to 0.5 μm, preferably 0.05 μm to
0.30 μm. Magnetic layer has different magnetic properties
It may be separated into two or more layers.
Applicable configurations are applicable. For example, a magnet having two magnetic layers
In the case of an air recording medium, a nonmagnetic layer and a soft magnetic layer may be provided.
For example, the magnetic layer far from the support
0.2-2 μm, preferably 0.2-1.5 μm,
The magnetic layer on the side closer to the support should be 0.8 to 3 μm.
Can do. In the case of having a magnetic layer alone,
0.2-5 μm, preferably 0.5-3 μm, more preferably
The thickness is preferably 0.5 to 1.5 μm. The thickness of the nonmagnetic layer is usually 0.2 to 3.0.
μm, preferably 0.3-2.5 μm, more preferably
0.5 to 2.0 μm. The lower layer is substantially non-magnetic.
If it is sex, it will exert its effect.
May contain a small amount of magnetic material as pure or intentionally
Yes. Substantially non-magnetic means that the residual magnetic flux density in the lower layer is 0.05.
T or less or coercive force is ~ 40% or less of upper magnetic layer
Preferably with zero residual magnetic flux density and coercivity
It is. In addition, as a lower layer, soft magnetic powder instead of the nonmagnetic layer
A soft magnetic layer containing a powder and a binder may be formed. Soft magnetic layer
The thickness of is the same as that of the lower layer. The total thickness of the magnetic recording medium of the present invention is 3 to 1.
The range of 0 μm is preferable, and 3 to 9 μm is more preferable.
Yes. The thickness of the back layer is preferably in the range of 0.2 to 0.8 μm.
A range of 0.2 to 0.7 μm is more preferable. [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.
And are preferred. [Support] The support used in the present invention comprises:
Polyethylene terephthalate, polyethylene naphthalate
Polyesters such as polyester, polyolefins, cellulose
Triacetate, polycarbonate, polyamide (fragrance
Aromatic polyamide and aliphatic polyamide), polyimide, poly
Riamideimide, polysulfone, polybenzoxazo
-A known film such as a glass can be used. Glass transition temperature
A support with a temperature of 100 ° C or higher is preferable, polyethylene
Use a high-strength support such as naphthalate or aramid.
Are particularly preferred. If necessary, magnetic surface and base surface
JP-A-3-224127 for changing the surface roughness of
It is also possible to use a laminated type support as shown in
Yes. These supports are pretreated with corona discharge,
Plasma treatment, easy adhesion treatment, heat treatment, dust removal treatment, etc.
You may go. [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 material and non-magnetic powder used in the present invention
Powder, binder, carbon black, abrasive, antistatic agent,
All raw materials such as lubricants, solvents, etc.
It may be added in the middle. Also, two individual raw materials
You may divide | segment and add in the above process. For example,
Polyurethane kneading process, dispersion process, viscosity adjustment after dispersion
It may be divided and added in the mixing step. Of the present invention
In order to achieve the objective, part of the conventional known manufacturing technology
This process can be used. Open in the kneading process
Kneader, continuous kneader, pressure kneader, extruder
It is preferable to use one having a strong kneading force. D
-In the case of using a magnetic material or non-magnetic powder and binder
All or part of it (however, 30% by weight or more of all binders)
15-50 with respect to 100 parts of magnetic material)
The kneading process is performed in the range of 0 part. Details of these kneading processes
JP-A-1-106338 and JP-A-1-79.
No. 274. Magnetic layer liquid and non-magnetic
Glass beads can be used to disperse the aqueous solution.
Zirconia Bee, a high-density 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. dispersion
Magnetic materials, abrasives, carbon black etc. with different speed
Dispersed separately in advance, mixed and further differentiated if necessary
It can be scattered to make a coating solution. 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, 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 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, it does not matter if you use sequential multilayer coating to provide layers,
The effect of the present invention is not lost. However, lack of application
Reduce traps and improve dropout quality
For this purpose, it is preferable to use the above-mentioned simultaneous multilayer coating.
Yes. As the calendering roll, epoxy, poly
Heat resistant such as imide, polyamide, polyimide amide
Treat with some plastic or metal roll
However, when using a double-sided magnetic layer, process 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
More than 200Kg / cm (196kN / m)
More preferably 300 kg / cm (294 kN / m) or less
Above. The magnetic recording medium of the present invention is worn against the head.
The friction coefficient ranges from -10 ° C to 40 ° C and 0% to 95% humidity.
0.5 or less, preferably 0.3 or less,
The resistance is preferably magnetic surface 10 ^Four -10 ¹² Ohm / s
q, The charging position is preferably within -500V to + 500V.
Yes. The elastic modulus at 0.5% elongation of the magnetic layer is favorable in each in-plane direction.
Preferably, 980-1960 MPa, breaking strength is preferable
Is 98 to 686 MPa, and the elastic modulus of the magnetic recording medium is in-plane
Direction preferably 980-14700 MPa, residual spread
Is preferably any temperature below 0.5% and below 100 ° C
The heat shrinkage rate in degrees is preferably 1% or less, more preferably
Is 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 lower is preferable, and that of the lower nonmagnetic layer is from 0 ° C. to 10 ° C.
0 ° C. is preferred. Loss modulus is 1 × 10 ⁷ ~ 8x10 ⁸ N
/ M ² The loss tangent is preferably 0.2.
The following is preferable. If the loss tangent is too large,
Contact failure is likely to occur. These thermal and mechanical properties are
It is preferable to be approximately equal within 10% in each direction in the body surface.
Yes. The residual solvent contained in the magnetic layer is preferably 100 m
g / m ² Or less, more preferably 10 mg / m ² Is
The The porosity of the coating layer is preferred for both non-magnetic and magnetic layers.
30 volume% or less, more preferably 20 volume% or less.
It is below. The smaller the porosity, the higher the output.
Although it is preferable, it is better to secure a certain value depending on the purpose.
There is a case. The magnetic layer was measured with an optical interference type surface roughness meter.
The center plane average surface roughness (Ra) is preferably 1 to 3 nm,
More preferably, it is 2.2 nm or less. Maximum magnetic layer
The height Rmax is 0.5 μm or less, and the 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 to 80% or less, and the average wavelength λa is 5 to 300 μm or less.
Below is preferred. The surface protrusion of the magnetic layer is 0.01 μm to 1 μm
Set m arbitrarily in the range of 0-2000.
It is possible to make electromagnetic conversion characteristics, friction
It is preferable to optimize the coefficients. These are the support
Add to surface control or magnetic layer by filler
Particle size and quantity of powder, roll surface shape of calendar processing, etc.
Can be easily controlled. Carl is ± 3
It is preferable to be within mm. EXAMPLES Specific examples of the present invention will be described below.
The invention is not limited to this. In the examples
“Parts” indicates “parts by mass” (Comparative Example 1) Magnetic layer composition Ferromagnetic metal powder [{Composition: Co / Fe = 23.5 / 10
0 (atomic ratio), Al / Fe = 9.6 / 100 (atomic
Ratio), Y / Fe = 9.6 / 100 (atomic ratio)}, Hc:
148 kA / m, S _BET : 79m ² / G, crystallite size:
108 mm, average long axis length: 0.059 μm, σs: 114
Am ² / Kg}] 100 parts in an open kneader for 10 minutes
10 parts polyurethane (UR-8300, manufactured by Toyobo Co., Ltd.) 6 parts (solid content) methyl ethyl ketone / cyclohexanone = 1/1 40 parts are added and kneaded for 60 minutes. did. Then α-Al ₂ O _Three (Average particle diameter 0.2 μm) 10 parts Carbon black (average particle diameter 80 nm) 2 parts Methyl ethyl ketone / cyclohexanone 200 parts 1/1 were added and dispersed in a sand mill for 120 minutes. Furthermore, polyisocyanate 4 parts (solid content) (Japan Polyurethane Coronate 3041) Stearic acid 1 part Fatty acid ester (butyl stearate) 2.5 parts Stearic acid amide 0.2 part Toluene 50 parts were added and stirred for 20 minutes. Then 1μm average pores
Filtration using a filter with a diameter to prepare a magnetic paint
did. The resulting magnetic coating has a thickness of 3 μm after drying.
As shown in the figure, polyethylene terephthalate with a thickness of 10 μm
(PET) Extrusion-type coating on the support surface
3,000 gauze with the magnetic coating in an undried state.
Magnetic field orientation is performed with a US magnet, and the following back solution is added.
The coating was dried so that the thickness after drying was 0.5 μm.
Then, a combination of metal roll and heat-resistant plastic roll
5-step calendar processing (100m / m speed)
in, linear pressure 300 kg / cm (294 kN / m), temperature 9
0 ° C.). After that, at 200 m / min, the width is reduced to 1/2 mm.
Lit and created a videotape. (Back liquid composition) Carbon black (particle size 18 nm) 100 parts Nitrocellulose (HIG1 / 2 manufactured by Asahi Kasei Corporation) 60 parts Polyurethane (N-2301 manufactured by Nippon Polyurethane Co., Ltd.) 60 parts Polyisocyanate (Coronate L manufactured by Nippon Polyurethane Co., Ltd.) 20 parts Methyl ethyl ketone 1000 parts Toluene 1000 parts (Examples 1 to 5, Comparative Examples 2 to 3)
Change the type and amount of fatty acid ester as shown in Table 1.
Except for the above, a tape was produced in the same manner as in Example 1.
did. About the obtained tape, it exists on the magnetic layer surface
Fatty acid ester quantification and fatty acid ester layer thickness below
It was calculated as follows. 60 prototype videotapes
Fatty acid esters stored in a high-temperature and high-humidity chamber at 90 ° C
To hydrolyze. 0, 5, 10, 20, 44, 6
Sampled in 8,92 hours, extracted with hexane, concentrated
Shrinkage and the change of fatty acid ester was examined by GC. Also
Separately, the specific surface area of the tape was determined by autosorb. Ingredients
Physically, the following steps were followed. Take 50cm of 1/2 inch tape in a beaker and distill n-
Add 30 ml of hexane, and add internal standard (tetracosa
0.001 wt / Vol%) 1 ml is added, and the temperature is 60 ° C.
And extract for 3 hours. Concentrate the extract to dryness and add a certain amount of hexane to redissolve.
This solution is subjected to GC analysis. Measurement is performed by GC. GC analysis conditions; Apparatus: Shimadzu GC-17A Column temperature: 150 to 260 ° C. (Temperature increase rate: 10 ° C. /
Min) Inlet temperature: 300 ° C. Detector temperature: 300 ° C. Column: J & W DB-1HT 30 m × 0.25 mm
Film thickness: 0.15 μm From the area ratio to the internal standard, the amount of fatty acid ester a
₀ Ask for. According to the method of FIG. 1, the horizontal axis represents the storage time t and the vertical axis represents ln.
(A ₀ / A _t ) Plot the fat present in the surface of the magnetic layer
The amount of acid ester was determined. The specific surface area of the tape was determined by autosorb. Obtained from the fatty acid ester amount of the coating layer surface obtained in step
The surface area of the magnetic layer
The thickness of the fatty acid ester was determined and shown in Table 1. Also, each
The still durability of the tape was evaluated by VTR. [Table 1] The thickness and thickness of the fatty acid ester layer on the surface of the magnetic layer
It correlates well with the chill characteristics, and the fatty acid energy on the surface of the magnetic layer.
It is clear that the thickness of the steal layer corresponds to the still property.
is there. The present invention provides a grease for the surface layer of a magnetic layer of a magnetic recording medium.
Preservation of fatty acid esters in a certain environment for hydrolysis
Separation, analysis using GC, HPLC, etc.
By calculating the reaction speed,
The abundance and thickness of fatty acid esters that should be present on the surface layer
In this way, the magnetic
Of fatty acid ester on the surface and the thickness of the fatty acid ester layer
This value can be used as a parameter
To develop magnetic recording media with good running characteristics
did it.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining how to determine the amount of fatty acid ester on the surface of a coating layer.

Claims (1)

1. A magnetic recording medium comprising a coating layer having a magnetic layer containing at least a ferromagnetic powder and a binder on a support, wherein the coating layer contains a fatty acid ester, and the coating layer comprises: A magnetic recording medium, wherein the fatty acid ester layer present on the surface has a thickness of 2 to 20 mm.