JP3384839B2 - Magnetic recording media - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium.
In more detail, electromagnetic output such as RF output and chroma S / N
The present invention relates to a magnetic recording medium having excellent switching characteristics and running durability. [0002] 2. Description of the Related Art
Carbon black has been designed to improve antistatic properties and
Added to the magnetic layer of the magnetic recording medium for the purpose of
You. When carbon black is added to the magnetic layer,
Is a problem. Because the car
If the average primary particle size of Bon Black is small,
Although the surface of the magnetic layer in the recording medium becomes smooth,
Running performance is poor due to increased frictional resistance between the pad and the magnetic layer.
Become On the other hand, if it is large, the dispersibility is poor and the magnetic layer
Since the surface becomes rough and frictional resistance is reduced,
It is said that although the performance is good, the electromagnetic conversion characteristics deteriorate
Because there is a problem. For this reason, magnetic recording having a single magnetic layer
In media, to improve the surface condition of the magnetic layer,
Combines carbon blacks with various average primary particle sizes
For example, Japanese Patent Publication No. 54-9 / 1979
041, JP-B-53-20203, JP-A-58-2
18039
You. However, the surface condition of the magnetic layer is not preferable.
Average primary particle size of carbon black or combination thereof
Forming a preferred magnetic layer simply by finding
And cannot improve the electromagnetic conversion characteristics of the magnetic recording medium.
You can't get it up. Because the magnetic layer is generally
It is formed by applying the paint for the magnetic layer.
Carbon black is used for the viscosity or fluidity of coatings for layers.
Properties such as oil absorption and pH have a great effect. Furthermore,
To improve the electromagnetic conversion characteristics of magnetic recording media, use magnetic powder.
This is because the type of powder has a great effect. Therefore, when carbon black is used,
In this case, not only the average primary particle size but also the oil absorption, p
H must also be considered. How to select magnetic powder
May be an important issue in improving the performance of magnetic recording media.
You. [0006] On the other hand, magnetite magnetic powder is an antistatic material.
It is effective in improving the light blocking, light shielding properties, electromagnetic conversion characteristics, etc.
Generally known. Such a magnet
When magnetite magnetic powder is used, magnetite magnetic powder
Low transmittance reduces the amount of carbon black added
can do. In this case, the effect of carbon black
The surface of the magnetic layer of the magnetic recording medium is flat.
Smoothness and electromagnetic conversion characteristics are improved. But on the other hand, magnetic
Frictional resistance on the surface of the functional layer increases, resulting in poor running durability
Tend. Therefore, magnetite magnetic powder and carbon
When used in combination with black, the presence of both particles is
To reflect good characteristics on magnetic recording media
Can be However, the combination is difficult and simply
The combined use alone does not provide the good properties.
No. For example, if the oil absorption is more than 100 (ml / 100g)
If low, the pH is less than 7.0,
When Bon Black is used, the dispersibility of the paint for the magnetic layer is not sufficient.
However, there is a problem that the liquidity is poor. As a result of the inventor's intensive studies, it has been found that Magneto
Specified average value for magnetic layer paint containing tight magnetic powder
To add carbon black with primary particle size
Loss of good properties of magnetite magnetic powder
The surface of the magnetic layer is made moderately rough and frictional resistance is reduced.
And improve the running durability of the magnetic recording medium
Can be. Furthermore, it has a specific pH and oil absorption.
By adding carbon black to the magnetic layer paint
Improves the fluidity of the magnetic layer paint and is sufficiently dispersed
A paint for a magnetic layer can be obtained. Find that
And arrived at the present invention. [0010] The present invention solves the above-mentioned problems and provides an RF output.
Excellent in electromagnetic conversion characteristics such as force, chroma S / N and running durability
The purpose of the present invention is to provide a magnetic recording medium. [0011] Means for Solving the Problems To Solve the Problems
The invention as set forth in claim 1 for the above-mentioned method is provided on a non-magnetic support.
At least one magnetic layer is provided, and the magnetic layer
FeO with metal-modified particle surface_x (1.34 ≦ x ≦
1.41) Magnetic powder with an average primary particle diameter of 40 mμ or more
Carbon black (1) having an average primary particle diameter of 2
5 to 40 μm, pH 7.0 or more, oil absorption 100 (m
l / 100 mg) or less,
Is a magnetic recording medium characterized by containing Hereinafter, the magnetic recording medium of the present invention will be described.
I do. [0013] The magnetic recording medium of the present invention comprises a non-magnetic support.
(1) Magnet containing magnetic powder and carbon black on top
At least one functional layer (2), and other if necessary
(3). (1) Non-magnetic support As a material for forming the nonmagnetic support, for example,
Polyethylene terephthalate, polyethylene-2,6-na
Polyesters such as phthalate and polyester
Reolefins, cellulose triacetate, cellulose
Cellulose derivatives such as sudiacetate, polyamide,
Examples of plastics such as polycarbonate
it can. The form of the non-magnetic support is particularly limited.
There is no limit, mainly tape, film, sheet, car
Disk, disk, drum, etc. The thickness of the nonmagnetic support is particularly limited.
No, but for example, in the case of film or sheet
3 to 100 μm, preferably 4 to 50 μm
About 30 μm to 10 mm for discs and cards
Degrees, and in the case of a drum,
Is selected. The non-magnetic support has a single-layer structure.
Or a multilayer structure. Also this
Non-magnetic support, for example, surface treatment such as corona discharge treatment
May be applied. The magnetic layer on the non-magnetic support may be
On the side not provided (back side), the running of the magnetic recording medium
For the purpose of improving the properties, antistatic and transfer prevention,
It is preferable to provide a back coat layer,
An undercoat layer can be provided between the magnetic support
You. (2) Magnetic layer The magnetic layer has at least one layer formed on a non-magnetic support.
It is. The magnetic layer may be formed of a plurality of layers as necessary.
You can also. The magnetic layer comprises a magnetic powder (A) and
Contains Bon Black (B). Furthermore, a binder
(C) and various additive components (D)
You. A. Magnetic powder The magnetic layer in the magnetic recording medium of the present invention is made of a ferromagnetic powder.
FeO whose particle surface is metal-modified_x (1.34 ≦
x ≦ 1.41) Contains magnetic powder as an essential component. Previous
When the X is within the above range, the light shielding property and the electromagnetic conversion characteristics are good.
Magnetic recording medium can be obtained. X is 1.41
If it exceeds, the light shielding property of the magnetic powder itself is reduced, and the VTR
Use a large amount of carbon black to achieve the specified transmittance of the jack
Must be contained, which may lead to a decrease in dispersibility.
There is. On the other hand, if it is less than 1.34, F in the magnetic powder
e²⁺Is excessive, which may also lead to a decrease in dispersibility.
Therefore, neither is preferable. FeO used in the present invention_x (1.34 ≦ x
≦ 1.41) The magnetic powder has a coercive force (Hc) of usually 5
00 to 900 Oё, preferably 600 to 800
  Oё. When the value of Hc is within the above range, low frequency
Improve the characteristics of the wave range (especially color output, etc.)
it can. The FeO used in the present invention_x (1.3
4 ≦ x ≦ 1.41) The magnetic powder usually has a BET value of 2
5-45m^Two / G. The BET value
Is within the above range, high-density recording is possible, and S / N
A magnetic recording medium with an excellent ratio can be easily realized.
You. Further, the FeO used in the present invention_x (1.3
4 ≦ x ≦ 1.41) The magnetic powder has an axial ratio of usually 8 to
15 and preferably 10 to 15. The axial ratio is
When the content is in the above range, an output having particularly excellent orientation and filling properties is obtained.
A high-power magnetic recording medium can be obtained. The above-mentioned FeO_x (1.34 ≦ x ≦ 1.41)
Is usually 15 to 3 with respect to the coating material for the magnetic layer.
5% by weight, preferably 20 to 30% by weight,
Particularly preferably, the content is 20 to 25% by weight. The content is
When the content is 35% by weight or more, the material other than the magnetic powder is relatively
As the amount decreases, the physical properties of the tape deteriorate and the magnetic layer is easily peeled.
Or increase the frictional resistance.
If it is less than 5% by weight, the magnetic force of the tape itself decreases,
Both are preferred because electromagnetic conversion characteristics may deteriorate.
I don't. In addition, the magnetic layer is required as a magnetic powder.
If necessary, a known ferromagnetic powder may be contained. So
Representative examples of the following ferromagnetic metal powder, γ-Fe_Two
O_Three, Co-containing γ-Fe_Two O_Three , Co-coated γ-Fe_Two O_Three
 , Fe_Three O_Four , Co-containing Fe_Three O_Four , Co-coated Fe_Three
O_Four , Co-containing magnetic FeO_x (3/2> X> 4/3),
CrO_Two Oxide magnetic material such as
Examples include tetragonal ferrite and iron nitride. Among these
Also preferred in the present invention are ferromagnetic metal powders. That is, among the magnetic powders, the following strong magnetic
With the use of conductive metal powder, the magnetic recording medium has a high recording density.
Can be achieved, resulting in excellent electromagnetic conversion properties
can get. Specific examples of the ferromagnetic metal powder include F
e, Ni, Co, Fe-Al, Fe-Al-C
a system, Fe-Al-Ni system, Fe-Al-Zn system, Fe
-Al-Co system, Fe-Ni system, Fe-Ni-Al system,
Fe-Ni-Co system, Fe-Ni-Si-Al-Mn
System, Fe-Ni-Si-Al-Zn system, Fe-Al-S
i-based, Fe-Al-Co-based, Fe-Ni-Zn-based, Fe
-Ni-Mn system, Fe-Ni-Si system, Fe-Mn-Z
n-based, Fe-Co-Ni-P-based, Co-Ni-based, etc.
e, Ni, Co, etc.
Can be mentioned. Among these, Fe-based metal powder is an electric characteristic.
Excellent in corrosion resistance and dispersibility.
Preferred are Fe-Al, Fe-Al-Ca, Fe
-Al-Ni system, Fe-Al-Zn system, Fe-Al-C
o-based, Fe-Ni-based, Fe-Ni-Al-based, Fe-Ni
-Si-Al-Zn system, Fe-Ni-Zn system, Fe-N
i-Si-Al-Mn-based and Fe-Ni-Co-based
It is an Fe-based metal powder. Further, preferred ferromagnetic gold for the present invention
The genus powder contains at least Fe atoms and Al atoms,
The content ratio of Fe atoms and Al atoms is expressed as Fe: A
1 = 100: 1 to 100: 20 and a ferromagnetic metal
Surface area of less than 100mm at analysis depth by powder ESCA
The content ratio of existing Fe atoms to Al atoms is expressed as the atomic ratio.
Fe: Al = 30: 30 to 70:30
Things. Alternatively, Fe atoms, Ni atoms, and Al atoms
And Si atoms, and Zn and Mn atoms.
At least one of which has a Fe atom content of 90
% And Ni atom content is 1 atom% or more and 10 atoms
% And less than 0.1 atom% and 5 atoms
%, Less than 5 atom when the content of Si atom is 0.1 atom% or more
%, Zn content and / or Mn content.
Amount (however, contains both Zn and Mn atoms)
In this case, the total amount is 0.1 atomic% or more and less than 5 atomic%.
And analysis depth by ferromagnetic metal powder ESCA
Atoms and Ni atoms existing in the surface area less than 100 °
, Al atom, Si atom, Zn atom and / or Mn source
Fe: Ni: Al: Si:
(Zn and / or Mn) = 100: (4 or less):
(10-60): (10-70): (20-80)
It is a ferromagnetic metal powder having the following structure. In the present invention, the recording height of the magnetic recording medium is
To increase the density, the specific surface area by the BET method is 45 m^Two
/ G or more of ferromagnetic metal powder is preferably used. This
The specific surface area here means the value measured by the BET method.
Surface area per gram expressed in square meters
It is. In the method of measuring the specific surface area by the BET method,
For details, refer to “Measurement of powder” (JM Dallaval).
1, Clydeorr Jr, Muta and others;
(Published by Toshosha Publishing Co., Ltd.) and "Chemical Handbook"
Application, p1170-1171 (Chemical Society of Japan; Maruzen)
(Issued on April 30, 1966)
You. As an example, first, a powder sample was placed 105 ° C before
Degassed while heating for 13 minutes later to remove adsorbed substances
After that, introduce the sample into the measuring device and set the initial pressure of nitrogen.
0.5 kg / m^Two Set to liquid nitrogen
The adsorption measurement was performed at the temperature (−105 ° C.) for 10 minutes.
U. The measuring device is a counter soap (Yuasa Ionics)
(Manufactured by K.K.). On the other hand, in the present invention, the preservation of the magnetic powder is carried out.
Preferred conditions exist for the magnetic force (Hc). That is,
Hc of the magnetic powder to be used is 600 O６００ or more.
Is preferred. With this condition, the magnetic recording medium
This is because the RF output in the short wavelength region is improved. The content of these magnetic powders is
It is usually 60 to 90 parts by weight based on the solid content of the layer, and is preferably used.
Or 70 to 80 parts by weight. B. Carbon black The magnetic layer is made of carbon black (1) and carbon black.
(2). In the present invention, carbon black
(1) means that the average primary particle diameter is 40 mμ or more.
Refers to carbon black. In addition, carbon black
H (2) means that the average primary particle diameter is 25 to 40 mμ;
pH 7.0 or more, oil absorption 100 (ml / 100m
g) Refers to the following carbon blacks. (Carbon black (1)) The carbon
Average primary particle size of black (1) is usually 40 mμ or more
, Preferably 40 to 80 mμ, and particularly preferably
Or 40 to 60 mμ. The average primary particle diameter is 40
If it is smaller than mμ, the running durability of the magnetic recording medium is deteriorated.
It is not preferable because it may cause Examples of the carbon black (1) include:
For example, KZ300 manufactured by Denki Kagaku Kogyo Co., Ltd.
Diameter: 40mμ), rabe made by Columbia Carbon Japan
500 (average primary particle diameter 56 mμ), Raven 450
(Average primary particle diameter 62 mμ), raben 420 (average primary particle size).
Secondary particle diameter 68mμ), Vulcan (Ca
bot Vulcan) Black Pearls 280 (Average)
(Primary particle diameter 41mμ), # 25 of Mitsubishi Chemical Industry Co., Ltd.
(Average primary particle diameter 47mμ) etc.
I can do it. Among these, the electrochemical industry
KZ300 manufactured by K.K. and # 2 manufactured by Mitsubishi Kasei Kogyo Co., Ltd.
5 is preferred. The content of the carbon black (1)
Is usually 0.1 to 10% by weight based on the coating material for the magnetic layer.
Yes, preferably 0.1 to 3% by weight, particularly preferred
Or 0.1 to 0.5% by weight. The content is 3 weight
%, The surface of the magnetic layer becomes rough and the electromagnetic conversion characteristics become poor.
It is not preferable because it may deteriorate. On the other hand, 0.1 weight
%, The friction coefficient of the magnetic layer is increased and the running resistance is increased.
It is not preferable because durability may be deteriorated. (Carbon black (2)) The carbon
The average primary particle diameter of black (2) is usually 10 to 40 m.
μ, preferably 25 to 40 μm, particularly preferably
Or 25-35 mμ. The average primary particle diameter is 4
If it is larger than 0 μm, the surface of the magnetic layer becomes rough and
This is not preferable because the properties may be deteriorated. On the other hand, 25mμ
If it is smaller than this, dispersion is difficult, and the state of aggregation in the magnetic layer
And may degrade the electromagnetic conversion characteristics.
Not good. The carbon black (2) is
Is 7.0 or more, preferably 7.0 to 9.0.
And particularly preferably 7.0 to 8.0. The p
When H is 7.0 or more, the oil absorption is 100 (ml / 10
0 mg) may cause inconvenience. Further, the carbon black (2) is
Oil absorption of 100 (ml / 100g) or less
Or less than 80 (ml / 100g), especially preferred
Or less than 70 (ml / 100 g). The oil absorption is
When the pH is 100 (ml / 100 g) or less, the pH is 7.0.
If it is less than the above, a problem may occur. As such carbon black (2),
For example, Raven 850 of Columbia Carbon Japan,
760 (average primary particle diameter 31, 30 mμ, oil absorption 70, 5
0ml / 100g, pH 7.0, 7.4) Cabot Corporation
CabotVulcan black par
Loose 900 (average primary particle diameter 15mμ, oil absorption 70ml
/ 100 g, pH 7.0), Black Pearls 800
(Average primary particle diameter 17mμ, oil absorption 75ml / 100
g, pH 8.0), # 44 of Mitsubishi Chemical Industry Co., Ltd. (average)
Primary particle diameter 21mμ, oil absorption 76ml / 100g, pH
8.0), CF9 (average primary particle diameter 40 mμ, oil absorption 6)
5 ml / 100 g, pH 8.0) and the like.
You. The content of the carbon black (2) is
Usually 5 to 40 with respect to 100 parts by weight of a binder described below.
0 parts by weight, preferably 10 to 350 parts by weight, particularly preferred
Or 25 to 200 parts by weight. 400 weight
If the amount is more than the amount, the magnetic powder in the magnetic layer will decrease relatively
And may degrade the electromagnetic conversion characteristics.
Absent. On the other hand, if it is less than 5 parts by weight, the light shielding of the magnetic layer
Function and antistatic properties, and function as a magnetic recording medium
Is undesirably reduced. C. binder In the present invention, as the binder used for the magnetic layer,
Resin modified by introducing functional groups, especially modified vinyl chloride resin
Fats and modified polyurethane resins (urethane elastomers
Modified polyester resin is preferable)
Can be mentioned. As the functional group, for example, -SO_Three M,
-OSO_Three M, -COOM and the following (Chemical Formula 1)
And the like are preferred. [0048] Embedded image (Where M is a hydrogen atom or lithium)
And alkali metals such as sodium.¹ And M
^Two Are hydrogen, lithium, potassium, sodium
Or an alkyl group;¹ And M^Two Is the same as
Or may be different. ) Modified resin is like this
If it contains a functional group, the modified resin and magnetic powder
Improves bleeding and further improves dispersibility of magnetic powder
In addition, the coagulation is also prevented, further improving the stability of the coating liquid.
Frequency characteristics from high to low
Of the magnetic recording medium in addition to the electromagnetic conversion characteristics.
Durability also improves. The above modified resins may be used alone.
Can be used, or two or more kinds can be used in combination. the latter
In the case of modified polyurethane resin and modified vinyl chloride resin
Are preferably used in combination. The modified resin is a vinyl chloride resin, poly
Urethane resin or polyester resin and negative in the molecule
Compound having a functional group and chlorine, such as Cl-CH_Two CH_TwoSO_Three
M, Cl-CH_TwoCH_TwoOSO_TwoM, Cl-CH_TwoCOOM, the following (Formula 2)
Condensed with the compound shown by the dehydrochlorination reaction
Can be manufactured. [0052] Embedded image In the present invention, the conventional magnetic recording medium
Thermoplastic resin, thermosetting resin, known in the field of body,
Reactive resin, electron beam curing resin, or these
Mixtures can be used or they can be
It can also be used in combination with a hydrophilic resin. In the latter case, the invention
Preferably for the purpose of the above, the modified resin and vinyl chloride-vinegar
It is used in combination with an acid vinyl copolymer. Examples of the thermoplastic resin include chloride
Vinyl-vinyl acetate copolymer, vinyl chloride-vinyl chloride
Den copolymer, vinyl chloride-acrylonitrile copolymer
Body, acrylate-acrylonitrile copolymer,
Acrylate-vinylidene chloride copolymer,
Lylic acid ester-vinylidene chloride copolymer, methacrylic acid
Acid ester-ethylene copolymer, polyvinyl fluoride, chloride
Vinylidene-acrylonitrile copolymer, acrylonitrile
Lil-butadiene copolymer, polyamide resin, polyvinyl
Rubutyral, cellulose derivatives (cellulose acetate
Tobutyrate), cellulose diacetate, cellulose
Striacetate, cellulose propionate, nitro
Cellulose, etc.), styrene butadiene copolymer, polye
Stell resin, chlorovinyl ether acrylate
Copolymer, amino resin and synthetic rubber-based thermoplastic resin
And the like. These are used alone
Or two or more of them may be used in combination. As the thermosetting resin or the reactive resin,
Is, for example, phenolic resin, epoxy resin, polyurethane
Tan curing resin, urea resin, melamine resin, alkyd
Resin, silicone resin, acrylic reaction resin, high molecular weight
Mixing of polyester resin and isocyanate prepolymer
Compound, methacrylate copolymer and diisocyanate
Mixtures with polymers, urea-formaldehyde resin, and
And polyamine resins. These are a kind alone
Or may be used in combination of two or more.
No. Examples of the electron beam irradiation curing resin include, for example,
Maleic anhydride type, urethane acrylic type, d
Poxy acrylic type, polyester acrylic type,
Polyether acrylic type, polyurethane acrylic type
Unsaturated prepolymers such as Ip and polyamide acrylic type
ー; Ether acrylic type, urethane acrylic tie
, Epoxy acrylic type, phosphoric acid ester acrylic
Ip, aryl type, hydrocarbon type, etc.
And the like. These are a kind alone
Or may be used in combination of two or more.
No. The amount of the binder in the magnetic layer
Is the FeO_x (1.34 ≦ x ≦ 1.41) Magnetic powder
Usually 1 to 200 parts by weight with respect to 100 parts by weight,
The preferred amount is 1 to 50 parts by weight. Formulation of the binder
If the amount is larger than the above range, the resulting FeO_x (1.3
4 ≦ x ≦ 1.41) The amount of the magnetic powder is reduced,
The recording density of the air recording medium may decrease.
If the amount is less than the above range, the strength of the magnetic layer is low.
And the running durability of the magnetic recording medium may decrease.
You. D. Various additive components In the present invention, if necessary, unless the purpose is impaired.
In the meantime, the magnetic layer is, for example, a curing agent, a lubricant, a dispersant,
Non-magnetic abrasive particles, conductive powder, surfactant, antistatic
Various additional components such as agents can be contained. The curing agent may be aromatic or aliphatic.
Polyisocyanate may be used in combination with the binder
it can. The aromatic polyisocyanate includes:
For example, tolylene diisocyanate (TDI) and this
And an active hydrogen compound.
Those having a range of 00 to 3,000 are preferred. The aliphatic polyisocyanate includes:
For example, hexamethylene diisocyanate (HMDI)
And its adducts with active hydrogen compounds.
Those having a molecular weight of 100 to 3000 are preferable, and
Non-cycloaliphatic polyisocyanates and their active hydrogenation
Adducts with compounds are preferred. The above aromatic or aliphatic polyisocyanate
The addition amount of the binder is usually 1/2 by weight relative to the binder.
0 to 7/10, preferably 1/10 to 1/2. The lubricant may be a fatty acid or a fat.
Acid esters can be mentioned. In this case,
The addition amount is preferably 0.2 to 10% by weight based on the magnetic powder.
And more preferably 0.5 to 5% by weight. The amount
If the amount is less than 0.2% by weight, the running property is likely to be reduced.
On the other hand, if it exceeds 10% by weight, the fatty acid
Or the output is likely to decrease. In addition, fatty acid
The amount of stell added is 0.2 to 10 weight based on the magnetic powder.
%, More preferably 0.5 to 5% by weight. Said
If the addition amount is less than 0.2% by weight, the still durability deteriorates.
On the other hand, if it exceeds 10% by weight, the fatty acid ester
Easily seeps out of the surface of the magnetic layer and lowers output
Sometimes. Combination of the above fatty acid and the above fatty acid ester
Fatty acids and fatty acids
The ratio with the ester is 10:90 to 90:10 by weight.
Preferably. The fatty acid may be a monobasic acid or a dibasic acid.
It may be a basic acid, and preferably has 6 to 30 carbon atoms,
The range of 12 to 22 is more preferable. As a specific example of the fatty acid, capron
Acid, caprylic acid, capric acid, lauric acid, myristic
Acid, palmitic acid, stearic acid, isostearic acid,
Linolenic acid, oleic acid, elaidic acid, behenic acid,
Lonic, succinic, maleic, glutaric, adipine
Acid, pimelic acid, azelaic acid, sebacic acid, 1,12
-Dodecane dicarboxylic acid, octane dicarboxylic acid, etc.
Can be mentioned. As the lubricant, for example, silicone oil
Il, graphite, molybdenum disulfide, carbon atoms
About 12 to 20 monobasic fatty acids (for example, stearin
Acid) and a monohydric alcohol having about 3 to 26 carbon atoms.
And the like. Specific examples of the fatty acid ester include
Rail oleate, isocetyl stearate, dioleyl
Malate, butyl stearate, butyl palmitate,
Butyl myristate, octyl myristate, octyl
Palmitate, pentyl stearate, pentyl palmi
Tate, isobutyl oleate, stearyl stearate
, Lauryl oleate, octyl oleate, isobu
Chilloleate, ethyl oleate, isotridecylo
Reate, 2-ethylhexyl stearate, 2-ethyl
Lehexyl palmitate, isopropyl palmitate,
Isopropyl myristate, butyl laurate, cetyl
-2-ethyl hexalate, dioleyl adipate, di
Ethyl adipate, diisobutyl adipate, diisode
Siladipate, oleyl stearate, 2-ethylhexyl
Xyl myristate, isopentyl palmitate, iso
Pentyl stearate, diethylene glycol-mono-
Butyl ether palmitate, diethylene glycol
Mono-butyl ether palmitate and the like may be mentioned.
it can. These fatty acids or fatty acid esters are
Each type is not limited to one type, and two or more types may be used in combination.
Can be. As the dispersant, caprylic acid, capri
Acid, lauric acid, myristic acid, palmitic acid,
C12-C18 fats such as aric acid and oleic acid
Acids; salts of these alkali metals or alkaline earth metals
Salts or amides thereof; polyalkylene oxides
Doalkyl phosphate ester; lecithin; trialkyl ester
Liolefinoxy quaternary ammonium salt; carboxyl
And azo compounds having a sulfonic acid group
Can be These dispersants are usually
Is used in the range of 0.5 to 5% by weight. As the non-magnetic abrasive particles, for example,
Luminous α-Al_Two O_Three (Corundum) etc., artificial Photoshop
Dam, fused alumina, silicon carbide, chromium oxide, die
Diamonds, artificial diamonds, garnet, emery (main
Ingredients: corundum and magnetite)
You. The content of the non-magnetic abrasive particles is based on the ferromagnetic powder.
And preferably not more than 20 parts by weight.
The average particle size is preferably 0.5 μm or less, more preferably 0.4 μm or less.
More preferred. In the present invention, for example, the lubricant
And the non-magnetic abrasive particles are contained in other layers in particular.
If possible, the contact characteristics with the head (slip running, abrasion resistance
Etc.) can be significantly improved. As the conductive powder, for example, carbon
Black, graphite, silver powder, nickel powder, etc.
Examples of the surfactant include natural, nonionic, and anionic surfactants.
On, cationic and amphoteric surfactants
it can. The content of the conductive powder is based on the magnetic powder.
And preferably not more than 10 parts by weight.
The particle size is preferably 40 mμ or less, more preferably 25 mμ or less.
Good. Further, the conductive powder and the surfactant
, Especially in the magnetic layer as appropriate,
Resistance can be effectively reduced, and
Noise and dropout due to dust adhesion
Can be prevented. As the antistatic agent, carbon black
Conductive powders such as graphite and graphite;
Thione surfactant; sulfonic acid, sulfuric acid, phosphoric acid, phosphoric acid
Anionic surfactants containing acid groups such as esters and carboxylic acids
Agent; amphoteric surfactant such as aminosulfonic acid; saponin
And other natural surfactants. Mentioned above
The antistatic agent is usually 0.01 to 40 with respect to the binder.
It is added in the range of weight%. The thickness of the above-mentioned magnetic layer is 0.1 to 0.1.
It is preferably 4.0 μm, and more preferably 0.1 to 2.0 μm.
Preferably it is 5 μm. One magnetic layer is formed
Or two or more layers may be formed. (3) Other layers In the present invention, if necessary, unless the purpose is impaired.
First, another layer is provided between the magnetic layer and the non-magnetic support.
Can be Other layers are magnetic layers containing magnetic powder.
Even a non-magnetic layer containing a non-magnetic powder
You may. Other layers are basically the same as those of the magnetic layer.
Binders of the same type and blending amount as described in
Contains additional components, known per se non-magnetic powder, etc.
Can be. As a binder contained in other layers
Is of the same type as the binder contained in the magnetic layer,
Preferably it is. And as the binder,
Polyurethane resins having sulfonic acid groups are preferred. Further, in this other layer, the fatty acid is magnetic.
If it is not included in the layer, it may contain fatty acids
is necessary. About the kind of fatty acid,
It is the same as described above. The purpose of the present invention is also impaired in other layers.
Unless otherwise stated, the description of the magnetic layer
The same type and amount of lubricant, non-magnetic abrasive particles,
It may contain various additives such as conductive powders and surfactants.
Can be. The thickness of the other layers is usually from 0.1 to
2.0 μm, preferably 0.1 to 1.5 μm
You. Other layers may be formed as one layer or as two or more layers.
It may be formed. --- Manufacture of magnetic recording medium-- The magnetic recording medium of the present invention is not particularly limited in its manufacturing method.
No, manufactured according to a known method for manufacturing a magnetic recording medium
be able to. For example, generally, magnetic powder, binder
Kneading and dispersing the magnetic layer forming components such as
After the paint is prepared, this paint for the magnetic layer is applied to the non-magnetic support.
Apply to the surface. Examples of the solvent include acetone and methyl.
Ethyl ketone (MEK), methyl isobutyl ketone
Ketones such as (MIBK) and cyclohexanone: methano
Alcohol, ethanol, propanol, etc., vinegar
Methyl acid, ethyl acetate, butyl acetate, propyl acetate, milk
Ethyl acid, ethylene glycol monoacetate, etc.
Ter system: diethylene glycol dimethyl ether, 2-
Ethoxyethanol, tetrahydrofuran, dioxane
Ethers such as benzene, toluene and xylene
Aromatic hydrocarbons: methylene chloride, ethylene chloride
Carbon tetrachloride chloroform, ethylene chlorohydrin,
Use halogenated hydrocarbons such as dichlorobenzene
be able to. When preparing the coating material for the magnetic layer,
Powder, carbon black, binder and various additives
The minutes are charged simultaneously or individually to the kneader. For example,
The magnetic powder is added to a solution containing a dispersant, and mixed for a predetermined time.
After kneading, add the remaining components and continue kneading
A paint for magnetic layer. For kneading and dispersing components of magnetic layer
Therefore, various kneaders can be used. The kneading machine is, for example, a pressure kneader.
ー, continuous kneader, dissolver, two-roll mill, three
Main roll mill, ball mill, pebble mill, side gly
, High speed impeller disperser, high speed stone mill, high
Speed impact mill, disperser, high speed mixer, ho
Examples include a homogenizer and an ultrasonic disperser. The coating method is not particularly limited, and is well known.
Can be used. As a method for applying the coating material for the magnetic layer, for example,
For example, gravure coating method, knife coating method,
Wire bar coating method, doctor blade coating
Coating method, reverse roll coating method, dipco
-Method, air knife coating method, calendar co
Coating method, skis coating method, kiss coaty
Method, funting coating method, extrusion
There is an extrusion-type coater of the same type. Coating the coating material for the magnetic layer on the surface of the non-magnetic support
After that, the magnetic field is generally applied to the coating in the undried state.
Processing, and further using a super calendar roll etc.
And then cut into the desired shape.
Thereby, a magnetic recording medium can be obtained. The magnetic recording medium of the present invention has an electromagnetic conversion characteristic.
Excellent light shielding and erasing properties, and
Blooming and head dirt are also effectively prevented. [0091] Embodiments of the present invention will be described below. less than
The indicated components, proportions and order of operation deviate from the scope of the invention.
Various changes can be made without departing from the scope. Note that, in the embodiment,
In the description, "parts" are all "parts by weight". (Examples 1 to 9 and Comparative Examples 1 to 6)
Kneading each component of the composition using a kneader / sand mill
It was dispersed to prepare a coating material for a magnetic layer. [0093] ｝ Paint for magnetic layer｝   Co-γ-FeO_x ・ ・ ・ ・ ・ ・ ・ ・ ・ 100 copies     (Hc: 700 Oё, BET: 30-35 m^Two / G)   0.5 parts carbon black (1)   Carbon black (2) ... 10 parts   α-alumina 5 parts   Vinyl chloride-vinyl acetate-vinyl alcohol copolymer ... 10 parts     (UCH: VAGH)   Polyurethane resin (solid content) 10 parts     (N-3132 manufactured by Nippon Polyurethane Co., Ltd.)   Myristic acid 1.5 parts   Stearic acid 1.5 parts   Butyl stearate 1.0 part   Coronate L 2 parts   Cyclohexanone 100 parts   Methyl ethyl ketone: 100 parts   Toluene 100 parts. The ferromagnetic powder and carbon shown in Table 1
For the above magnetic layer containing black (1) and (2)
Using paint, a 14.5 μm thick polyethylene
After coating on the phthalate film,
Magnetic field orientation treatment and then drying.
Surface smoothing with a calendar to form the magnetic layer.
Done. The original magnetic tape thus obtained is slipped.
To create a 1/2 inch wide video magnetic recording medium
did. The following evaluation test was conducted for this magnetic recording medium.
Was. The results are shown in Table 2. << Evaluation Test >> <Dynamic friction coefficient>: Tape running tester TBT-300D
(Yokohama System Laboratory Co., Ltd.), 25 ° C environment
Bottom, 180mm tape on 4 pin chrome plated stainless steel
° Winding, tape speed 3.3 cm / sec, entrance
Measured with a tension of 20 g, and μ_k Was calculated. Μ_k = (1 / π) ln (x / 20) (Where x is the outlet tension (g)) <Electrical characteristics (dB) RF output>; VTR for RF measurement
The deck is HR-S6000 (JVC)
RF of 100% white signal at 4 MHz
The output was measured. The measured value is
Value. <Chroma S / N>: Color video noise
925 D / 1 (made by Shibasoku Co., Ltd.)
R-S6000 (Victor Japan Corporation) VTR
VHS-SG at a frequency of 629 KHz
The value (dB) for (Konica Corporation) was determined. <Running durability>; VCR HR-S6
000 (manufactured by Victor Company of Japan) at a temperature of 40 ° C.
In an environment with a humidity of 80%, the tape can be run repeatedly for 10 full lengths.
Performed for 0 hours and evaluated edge damage in the following two stages
Valued. ：: No edge damage occurred ×: Edge damage occurred over the entire length of the tape. <Coating viscosity at the time of dispersion>;
Rotor N with Brookfield B-type viscometer
o. The mixture was stirred for 1 minute at a rotation speed of 20 rpm with RD-5.
The value obtained by multiplying the subsequent measured value by 200 was defined as the paint viscosity at the time of dispersion. [0102] [Table 1][0103] [Table 2][0104] According to the present invention, the friction coefficient on the surface of the magnetic layer
Improve running durability by setting the number to an appropriate value
To improve the dispersibility of the paint for the magnetic layer.
That the production process for the coating for the functional layer can be stabilized.
In addition, magnetic power with excellent electrical characteristics such as RF output and chroma S / N
A recording medium can be provided.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kiyoto Fukushima 1-1-13 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation (72) Inventor Sadafumi Iijima 1-13-1 Nihonbashi, Chuo-ku, Tokyo (56) References JP-A-4-23217 (JP, A) JP-A-2-35626 (JP, A) JP-A-63-209022 (JP, A) JP-A-2-122418 ( JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G11B 5/70

Claims (1)

(57) [Claim 1] At least one magnetic layer is provided on a non-magnetic support.
A FeO _x (1.34 ≦ x ≦ 1.41) magnetic powder whose particle surface is metal-modified,
A carbon black (1) having an average primary particle size of 40 mμ or more, and a carbon black (2) having an average primary particle size of 25 to 40 mμ, a pH of 7.0 or more, and an oil absorption of 100 (ml / 100 mg) or less. A magnetic recording medium comprising: