JP2003223709A - Flexible magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the number of a magnetic duplication cycle by composing a flexible magnetic recording medium so that it is hard to generate corrosion on a master support surface for magnetic duplication. <P>SOLUTION: The polyurethane resin containing at least a kind of polar group in a range from 0.05 to 0.7 meq/g is made to contain at 60% by weight or more with respect to the total amount of resin in a magnetic layer into the magnetic layer of the flexible magnetic recording medium which has a coating layer including the magnetic layer and a non-magnetic layer. The polar group is selected from -SO<SB>3</SB>M, -OSO<SB>3</SB>M, -P=O(OM)<SB>2</SB>, -O-P=O(OM)<SB>2</SB>and -COOM (M expresses hydrogen atom, alkali metal, or ammonium salt). <P>COPYRIGHT: (C)2003,JPO

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-density magnetic recording medium.
Magnetic disk for high capacity data recording
The preformat signal is recorded by magnetic transfer.
On flexible magnetic recording media to be recorded
The In general, the amount of information in a magnetic recording medium is
With a large capacity and low cost to record a lot of information with the increase in
More preferably, the necessary parts can be read out in a short time.
And so-called high-speed accessible media is desired.
The One example is a high-density flexible disk.
Known and narrow as a technology to realize its large capacity
The magnetic head scans the track width accurately and has a high S / N ratio.
So-called tracking servo technology
However, it plays a big role. This technology
Servo signal for tracking at certain intervals in one lap
Address information signals, regenerated clock signals, etc.
It is recorded as a format. The magnetic head has such a preformat.
By reading the signal and correcting its position,
It is set to be able to travel on the track accurately
The The current preformat is that the disk is a dedicated server.
Recorded one by one and one track by using the recording device
It is. However, the servo recording device is expensive.
And it takes time to create a preformat,
This process will occupy a large part of the manufacturing cost.
Therefore, it is desired to reduce the cost.
Instead of writing preformats rack by rack,
A method of realizing it by a copying method has also been proposed. For example, Japanese Patent Laid-Open No. 63-183623.
In Japanese Patent Application Laid-Open No. 10-40544, information on the surface of a substrate is disclosed.
An uneven shape corresponding to the information signal is formed, and there are few uneven shapes.
Magnetic transfer mask with a ferromagnetic thin film formed on the surface of the projection
Apply the ferromagnetic thin film or ferromagnetic powder on the surface of the star carrier.
Sheet-like or disk-like magnetic recording medium with layers formed
Touching the surface of the body, or even an alternating bias magnetic field,
Or a ferromagnetic material that forms a convex surface by applying a DC magnetic field
Magnetized pattern corresponding to uneven shape
A method for recording a disk on a magnetic recording medium has been proposed. This method pushes the convex surface of the master carrier.
Simultaneously in close contact with the magnetic recording medium to be reformatted
By exciting the ferromagnetic material that forms the convex part,
A transfer method for forming a predetermined format on a recording medium.
Yes, relative to the magnetic transfer master carrier and the magnetic recording medium
To record statically without changing the general position
Is possible, and accurate preformat recording is possible.
In addition, the time required for recording is extremely short. [0007] As described above, magnetic transfer
Can be preformatted accurately and quickly
It is a technology that has the superior advantage of
If the magnetic transfer is repeated repeatedly, the magnetic transfer master
The body surface is made of vinyl chloride or the like contained in the magnetic recording medium.
Will gradually corrode and the recorded signal quality will deteriorate.
There was a problem. The present invention has been made in view of the above circumstances.
The surface of the magnetic transfer master carrier is corroded.
It is possible to suppress and increase the number of magnetic transfer cycles
To provide a flexible magnetic recording medium
Is. SUMMARY OF THE INVENTION The flexible magnet of the present invention.
The recording medium has a magnetic pattern according to the information to be transferred.
The information is transferred by closely contacting the magnetic transfer master carrier.
The nonmagnetic layer and the magnetic layer are placed on the nonmagnetic support to be copied.
A flexible magnetic recording medium formed in order,
The magnetic layer is -SO _Three M, -OSO _Three M, -P = O
(OM) ₂ , -OP = O (OM) ₂ And -COOM (M is
Represents hydrogen atom, alkali metal or ammonium salt)
At least one polar group selected from 0.05 to 0.
Including polyurethane resin contained in the range of 7 meq / g
The content of the polyurethane resin is the whole tree in the magnetic layer.
It is characterized by being 60% by weight or more of the fat amount
The -SO _Three M, -OSO _Three M, -P = O (O
M) ₂ , -OP = O (OM) ₂ And -COOM (M is water
Represents an elementary atom, an alkali metal or an ammonium salt)
At least one polar group selected from 0.05 to 0.
It contains in the range of 7 meq / g, Preferably it is 0.1-0.
In the range of 5 meq / g, further 0.2-0.4 meq /
The range of g is preferable. The content of the polyurethane resin is determined by the magnetic field.
70% by weight or more of the total resin amount in the adhesive layer, 70
% By weight is preferable, 100% by weight,
That is, all the resin in the magnetic layer is the polyurethane resin.
Also good. The flexible magnetic recording medium of the present invention comprises:
-SO for the magnetic layer _Three M, -OSO _Three M, -P = O (OM)
₂ , -OP = O (OM) ₂ And -COOM, where M is a hydrogen source
Or represents an alkali metal or ammonium salt)
0.05 to 0.7 me of at least one polar group
A polyurethane resin containing q / g in the magnetic layer
Since 60% by weight or more of the total resin content is included, magnetic transfer
Cause corrosion of vinyl chloride from the magnetic recording medium.
Prevents material from moving and corroding the surface of the master carrier
Signal products that can be recorded on magnetic recording media
Long-term stability. Also, polyurethane with a high content of polar groups
Magnetic powder in the magnetic layer by using a predetermined amount or more of resin
Improve body dispersibility and achieve uniform dispersion
Therefore, it is possible to obtain a sufficient S / N ratio. DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
I will explain. The flexible magnetic recording medium of the present invention has a magnetic
Sex layer is -SO _Three M, -OSO _Three M, -P = O (O
M) ₂ , -OP = O (OM) ₂ And -COOM (M is water
Represents an elementary atom, an alkali metal or an ammonium salt)
At least one polar group selected from the following (hereinafter referred to as a specific polarity)
Group)) in the range of 0.05 to 0.7 meq / g.
Containing polyurethane resin, including polyurethane resin
The amount is 60% by weight or more of the total resin amount in the magnetic layer. The flexible magnetic recording medium of the present invention is a magnetic recording medium.
Specific layer as a binder in a certain range
Including 60% by weight or more of the total amount of polyurethane resin
Therefore, the binder of the nonmagnetic layer is a known one which will be described later.
Binder can be used, but is contained in the magnetic layer
The above polyurethane resin may be used and is flexible
The binder used for the magnetic recording medium is the predetermined polyurethane.
By using tan resin, recording on the magnetic recording medium is further possible.
Long-term stability of recorded signal quality can be achieved. The specific polar group is 0.05 to 0.7 meq /
It contains in the range of g. Certain polar groups are outside this range
And it becomes difficult to disperse | distribute magnetic powder favorably. Po
The alkyl group of the urethane resin preferably has 1 to 1 carbon atoms.
18, which may be a linear structure or a branched structure
Yes. As the polyurethane resin, for example, a cyclic resin
Molecular weight with structure and alkylene oxide chain 50
0-5000 polyols and cyclic structures as chain extenders
Polyol having a molecular weight of 200 to 500 and organic diiso
It was obtained by reacting cyanate, and the above
Polyurethane resin (A) containing a polar group in the above range, fat
It has a cyclic structure with an aliphatic dibasic acid and an alkyl branched side chain.
Polyester polyol composed of a rare aliphatic diol
And a branched alkyl side chain with 3 or more carbon atoms as a chain extender
Anti-aliphatic diol and organic diisocyanate compound
And the polar group is in the above range.
Containing polyurethane resin (B), cyclic structure and carbon number
Polyol compound having two or more alkyl chains and organic diester
It was obtained by reacting isocyanate, and
A polyurethane resin (C) containing the polar group in the above range,
Preferably it can be mentioned. Polyurethane resin (A) Cyclic structure and a starting material for polyurethane resin (A)
Examples of polyols having a ruxylene oxide chain include ring
Diols having a structure like ethylene oxide and propylene
Added with alkylene oxide such as lenoxide
Can be used. Specifically, bisphenol
A, hydrogenated bisphenol A, bisphenol S, hydrogen
Bisphenol S, Bisphenol P, Hydrogenated Bisph
Enol P, tricyclodecane dimethanol, cyclohexane
Xanthanimethanol, cyclohexanediol, 5,
5 ′-(1-methylethylidene) bis- (1,1′-bi
(Cyclohexyl) 2-ol, 4,4 ′-(1-methyl)
Ethylidene) bis-2methylcyclohexanol, 5,
5 ′-(1,1′-cyclohexylidene) bis- (1,
1'-bicyclohexyl) 2-ol, 5,5'-
(1,1'-cyclohexylmethylene) bis- (1,
1'-bicyclohexyl) 2-ol, hydrogenated terpene
Phenol, diphenylbisphenol A, diphenyl
Bisphenol S, diphenylbisphenol P, 9,
9-bis- (4-hydroxyphenyl) fluorene,
4,4 '-(3-Methylethylidene) bis (2-cyclo
(Hexyl-5-methylphenol), 4,4 '-(3-
Methyl ethylidene (bis (2-phenyl-5 methyl cycl
Lohexanol), 4,4 '-(1-phenylethylide)
) Bis (2-phenol), 4,4′-cyclohexyl
Redenbis (2-methylphenol), terpene diphe
A diol such as a diol can be used. Above all, water
Of hydrogenated bisphenol A and hydrogenated bisphenol A
Polypropylene oxide adducts are preferred. Above poly
The molecular weight of all is preferably 500-5000
That's right. If the molecular weight is 500 or more, the urethane group concentration is low.
Solvent solubility is high and molecular weight is 5000 or less
The coating film strength is good and the durability can be increased. Polymer having a cyclic structure used as a chain extender
As a riol, a diol having the above cyclic structure is used.
And ethylene oxide in the molecular weight range of 200-500
Alkylene oxide such as propylene oxide
Added ones can be used. Preferably hydrogenation
Pros of bisphenol A and hydrogenated bisphenol A
Examples include pyrene oxide adducts. Polyurethane resin (B) Polyester resin used as a raw material for polyurethane resin (B)
All have an aliphatic dibasic acid and an alkyl branched side chain
It consists of an aliphatic diol having no cyclic structure. Aliphatic II
Basic acids include succinic acid, adipic acid, azelain
Acid, sebacic acid, malonic acid, glutaric acid, pimelic acid,
Aliphatic dibasic acids such as suberic acid can be used
The Of these, succinic acid, adipic acid, and sebacic acid are preferred.
Yes. Of all dibasic acid components of polyester polyol,
The content of the aliphatic dibasic acid is preferably 70 mol% or more.
Good. When it is 70 mol% or more, a substantially cyclic structure is formed.
Good solvent solubility due to low concentration of dibasic acid
Can improve the dispersibility. Because it is used for polyester polyols
Non-cyclic structure with an alkyl branched side chain
As the group polyol, 2,2-dimethyl-1,3-propyl is used.
Lopandiol, 3,3-dimethyl-1,5-pentane
Diol, 2-methyl-2-ethyl-1,3-propane
Diol, 3-methyl-3-ethyl-1,5-pentane
Diol, 2-methyl-2-propyl-1,3-propa
Diol, 3-methyl-3-propyl-1,5-pen
Tandiol, 2-methyl-2-butyl-1,3-pro
Pandiol, 3-methyl-3-butyl-1,5-pen
Tandiol, 2,2-diethyl-1,3-propanedi
All, 3,3-diethyl-1,5-pentanedioe
2-ethyl-2-butyl-1,3-propanedioe
3-ethyl-3-butyl-1,5-pentanedioe
2-ethyl-2-propyl-1,3-propanedio
, 3-ethyl-3-propyl-1,5-pentanedi
All, 2,2-dibutyl-1,3-propanedioe
3,3-dibutyl-1,5-pentanediol,
2,2-dipropyl-1,3-propanediol, 3,
3-dipropyl-1,5-pentanediol, 2-buty
Ru-2-propyl-1,3-propanediol, 3-butyl
Til-3-propyl-1,5-pentanediol, 2-
Ethyl-1,3-propanediol, 2-propyl-
1,3-propanediol, 2-butyl-1,3-pro
Pandiol, 3-ethyl-1,5-pentanedioe
3-propyl-1,5-pentanediol, 3-butyl
Til-1,5-pentanediol, 3-octyl-1,
5-pentanediol, 3-myristyl-1,5-pen
Tandiol, 3-stearyl-1,5-pentanedio
2-ethyl-1,6-hexanediol, 2-propyl
Lopyl-1,6-hexanediol, 2-butyl-1,
6-hexanediol, 5-ethyl-1,9-nonane
All, 5-propyl-1,9-nonanediol, 5-
Branched aliphatic dio such as butyl-1,9-nonanediol
Can be used. Among them, 2,2-dimethyl
-1,3-propanediol, 2-ethyl-2-butyl
-1,3-propanediol, 2,2-diethyl-1,
3-propanediol is preferred. Polyester polio
Polyol having branched side chains in the polyol used in the process
Is preferably 50 to 100 mol%,
It is preferable that it is 70-100 mol%. the above
By making it within the range, the solvent solubility is high,
Dispersibility can be obtained. In the polyurethane resin (B), a chain extender and
An aliphatic di-chain having 3 or more branched alkyl side chains
All can be used. Has 3 or more carbon atoms,
In addition, having a branched alkyl side chain improves solvent solubility.
And good dispersibility can be obtained. It has a branched alkyl side chain having 3 or more carbon atoms.
As the aliphatic diol, 2-methyl-2-ethyl-
1,3-propanediol, 3-methyl-3-ethyl-
1,5-pentanediol, 2-methyl-2-propyl
-1,3-propanediol, 3-methyl-3-propi
1,5-pentanediol, 2-methyl-2-buty
1,3-propanediol, 3-methyl-3-buty
1,5-pentanediol, 2,2-diethyl-
1,3-propanediol, 3,3-diethyl-1,5
-Pentanediol, 2-ethyl-2-butyl-1,3
Provandiol, 3-ethyl-3-butyl-1,5
-Pentanediol, 2-ethyl-2-propyl-1,
3-Provandiol, 3-ethyl-3-propyl-
1,5-pentanediol, 2,2-dibutyl-1,3
-Propanediol, 3,3'-dibutyl-1,5-pe
Nthanediol, 2,2-dipropyl-1,3-propa
Diol, 3,3-dipropyl-1,5-pentanedi
All, 2-butyl-2-propyl-1,3-propane
Diol, 3-butyl-3-propyl-1,5-penta
Diol, 2-ethyl-1,3-propanediol,
2-propyl-1,3-propanediol, 2-butyl
-1,3-propanediol, 3-ethyl-1,5-pe
Nthanediol, 3-propyl-1,5-pentanedio
3-butyl-1,5-pentanediol, 3-o
Cutyl-1,5-pentanediol, 3-myristyl-
1,5-pentanediol, 3-stearyl-1,5-
Pentanediol, 2-ethyl-1,6-hexanedio
2-propyl-1,6-hexanediol, 2-
Butyl-1,6-hexanediol, 5-ethyl-1,
9-nonanediol, 5-propyl-1,9-nonane
Uses all, 5-butyl-1,9-nonanediol, etc.
can do. Among them, 2-ethyl-2-butyl-
1,3-propanediol, 2,2-diethyl-1,3
-Propanediol is preferred. In polyurethane resin
The content is preferably 5-30% by mass, more preferably 10-2.
It is preferably 0% by mass. Within the above range,
Solvent solubility is high and good dispersibility can be obtained. Polyurethane resin (C): cyclic structure and carbon as raw material for polyurethane resin (C)
The polyol compound having an alkyl chain of 2 or more prime numbers is
A diol having a molecular weight of 500 to 1000 is preferred.
Yes. If it is a diol, it will be cross-linked during polyurethane polymerization.
This is preferable because no gelation occurs. In addition, the diol
If the alkyl chain has 2 or more carbon atoms, solvent dissolution
High dispersibility and good dispersibility. With molecular weight over 500
If there is, the solvent solubility is high because the urethane group concentration is low,
When it is 1000 or less, the coating film strength is good. Annular structure
And a polyol having an alkyl chain having 2 or more carbon atoms;
It can be obtained by hydrogenating and reducing dimer acid.
For example, dimer diol represented by the structure of the following formula is preferred.
Yes. ## STR1 ## Geo having a cyclic structure and an alkyl chain having 2 or more carbon atoms
Is contained in the polyurethane resin in an amount of 5 to 60% by mass.
Preferably 10 to 40% by mass.
And are preferred. Cyclic structure and alkyl having 2 or more carbon atoms
If the content of the chain-containing diol is within the above range,
High agent solubility, good dispersibility, and high durability
can do. In the present invention, it is reacted with the above polyol.
Organic used to form polyurethane resin
Diisocyanate is not particularly limited and is usually used
Can be used. Specifically, for example,
Hexamethylene diisocyanate, tolidine diisocyanate
Nate, isophorone diisocyanate, 1,3-xylyl
Range isocyanate, 1,4-xylylene diisocyanate
Nate cyclohexane diisocyanate, toluidine di
Isocyanate, 2,4-tolylene diisocyanate,
2,6-tolylene diisocyanate, 4,4'-diphe
Nylmethane diisocyanate, p-phenylene diisocyanate
Anate, m-phenylene diisocyanate, 1,5-
Naphthalene diisocyanate, 3,3-dimethylpheny
A range isocyanate etc. can be mentioned. From raw material monomers introduced with polar groups,
Polyethylene having polar groups can be produced by producing a retane resin.
A urethane resin can be manufactured. For example, polar groups
Polyester polyol, polyether polyol having
Polyol and other polar group-containing polyols and
Polyester polyol, polyether polyol, etc.
A method of producing from diol and diisocyanate, bivalent
Diol containing polar group of alcohol or dibasic acid
Or to change to polar group-containing dibasic acid
Can be manufactured more. Polar group-containing polyol or
Is a polar group-containing dibasic acid, for example, the polyol or
-SO in the main chain or side chain of the dibasic acid ₃ M, -OSO
₃ M, -PO (OM) ₂ , -OPO (OM) ₂ ,and
-COOM (M is a hydrogen atom, alkali metal or ammonia)
At least one polar group selected from
It contains. Polar group-containing polyureta used in the present invention
The average molecular weight of the resin is 5,000 to 100,000.
Is more preferable, and it is 10,000 to 50,000.
It is preferable. Magnetism obtained when it is 5000 or more
High physical strength such as high coating film, durability of magnetic recording media
With a molecular weight of 100,000
The following is highly soluble in the solvent and improves dispersibility.
In addition, the paint viscosity at a given concentration is appropriate.
It should be easy to handle with good workability
Can do. The polar group-containing polyureta used in the present invention
The resin has a branched OH group, and is curable and durable.
2 to 40 per molecule is preferred
Furthermore, it is preferable that the number is 3 to 20 per molecule.
Good. In the present invention, other than the above polyurethane resin
A polyurethane resin can also be used in combination. Used together
The urethane resin has the same polarity as the polyurethane resin
It is more preferable to have a group. Chain elongation
As long-acting agents, polyvalent alcohol, a substance known per se.
, Aliphatic polyamines, alicyclic polyamines, aromatic polyamines
Liamine and the like can be used. Above all, molecular weight 50-500
Polyhydric alcohols are preferred. If it is 50 or more, the coating film strength
High durability and good durability, 500 or more
Below, the Tg of the paint film is high and the paint film becomes hard, so durability
It can be good. As the polyhydric alcohol, bisphenol
A, hydrogenated bisphenol A, bisphenol S, bis
Phenol P and their ethylene oxide, propylene
Lenoxide adduct, cyclohexanedimethanol,
Chlohexanediol, hydroquinone, bis (2-
Droxyethyl) tetrabromobisphenol A, bis
(2-Hydroxyethyl) tetrabromobisphenol
S, bis (2-hydroxyethyl) tetramethylbisph
Enol S, bis (2-hydroxyethyl) diphenyl
Bisphenol S, bis (2-hydroxyethyl) diph
Enylbiphenol, bis (2-hydroxyethyl) thio
Odiphenol, bis (2-hydroxyethyl) bisph
Enol F, biphenol, bisphenol fluoride
Bisphenol full orange hydroxyethyl acetate
Short chain diols having a cyclic structure such as tellurium are preferred. During ~
But bisphenol A, hydrogenated bisphenol A,
Sphenol S, bisphenol P and their ethylene
Lene oxide, propylene oxide adduct, cyclohex
Fragrances such as sandimethanol and cyclohexanediol
A diol having an alicyclic group or an alicyclic group is preferred. The binder of the present invention contains the above polar group
Polyurethane resin is used, but vinyl chloride resin and
Other resins such as acrylic resins may be used in combination. Both
When used, these resins are -S ₃ M, -OSO
₃ M, -PO (OM) ₂ , -OPO (OM) ₂ ,and
-COOM (M is a hydrogen atom, an alkali metal ion or
At least one selected from ammonium ions)
It is preferable to have a polar group. There are no particular restrictions on other resins that can be used in combination.
There is no known heat resistance that is conventionally used as a binder.
Plastic resins, thermosetting resins, reactive resins, and mixtures of these
Compound can be used. As a thermoplastic resin,
Lass transition temperature is −100 to 150 ° C., number average molecular weight is 1.
000-200000, preferably 10000-100
000 can be used. Specifically, chloride
Vinylidene, acrylonitrile, styrene, butadiene
Ethylene, vinyl butyral, vinyl acetal,
Polymers and copolymers containing vinyl ether as a structural unit
Body, various rubber resins. Also thermosetting resin or
As reactive resin, phenol resin, phenoxy resin,
Epoxy resin, urea resin, melamine resin, alkyd tree
Fat, acrylic reaction resin, formaldehyde resin, silica
Corn resin, epoxy-polyamide resin, polyester
Examples include mixtures of resins and isocyanate prepolymers.
It is. These resins are used alone or in appropriate combination
can do. In the present invention, the binder is a ferromagnetic powder or
Is a range of 5 to 50 parts by mass with respect to 100 parts by mass of the nonmagnetic powder.
It can be used at a content within the range. In particular, its content
Is set within a range of 7 to 45 parts by mass, thereby forming a magnetic layer
Or the phenomenon such as the glossiness of the surface of the non-magnetic layer increases.
Good dispersion of ferromagnetic or non-magnetic powder
Can be. Furthermore, the content is 10-40 quality
Electromagnetic conversion characteristics are significantly improved by setting within the mass range.
Will be improved. When the content is less than 5 parts by mass,
Magnetic powder or non-magnetic powder is not combined, causing powder falling.
On the other hand, even if blending more than 50 parts by mass, ferromagnetic powder
The dispersion state of the powder or non-magnetic powder does not improve any further,
In the magnetic layer, the degree of packing of the ferromagnetic powder decreases and the electromagnetic conversion characteristics are reduced.
May cause a drop. A magnetic recording medium basically has a magnetic layer and a non-magnetic layer.
Consisting of the lower layer of the layer, but at least one of the lower layer and the magnetic layer
Alternatively, the layers may be multi-layered. Therefore, the amount of binder in the binder
Of polyurethane resin or other resin
Amount, molecular weight of each resin forming the magnetic layer, polar group weight, etc.
Of course, it is possible to change each layer within the scope of the present invention.
Rather, it should be optimized at each layer,
A known technique regarding the configuration can be used. example
For example, when changing the amount of binder in each layer, scratches on the surface of the magnetic layer
To reduce the amount of binder, increase the amount of binder in the magnetic layer.
In order to improve the head touch against the
For example, increasing the amount of binder to give flexibility
However, in application, the range in which the effects of the present invention are exhibited.
It is preferable to optimize the range. The magnetic recording medium of the present invention has a coupling in a magnetic layer.
Basically known magnetic recording except that the agent is specified.
The recording medium and its configuration are the same. Above all, practically non-magnetic
And a ferromagnetic powder or strong
Disperse magnetic hexagonal ferrite fine powder in binder
A magnetic recording medium having a magnetic layer is preferably used.
it can. This magnetic recording medium has a magnetic layer thickness of 0.5 μm.
In addition to the following thin films, high strength and excellent surface smoothness
The Therefore, by using this magnetic recording medium,
Excellent magnetism with high recording density and higher durability
A recording medium can be obtained. In the following, this magnetic recording medium is suitable for use.
An example will be described. [Magnetic layer] Coercive force of magnetic layer of magnetic recording medium
Hc is preferably 143 kA / m (1800 Oe) or more.
More preferably 159 kA / m (2000 Oe) or less
Furthermore, 183 to 279 kA / m (2300
˜3500 Oe) is preferred. 143
High recording density is improved by using kA / m or more.
Can be achieved. (Ferromagnetic powder) Ferromagnetic material used in the upper magnetic layer
Ferrous powder can be ferromagnetic metal powder or hexagonal ferrite
Tow powder is preferably used. As ferromagnetic metal powder
Preferably have a major axis length of 150 nm or less. Also,
Hexagonal ferrite powders of 35nm or less
preferable. The ferromagnetic metal powder is mainly composed of α-Fe.
Ferromagnetic alloy powder is preferred. These ferromagnetic metal powders
In addition to predetermined atoms, Al, Si, S, Sc, Ca, T
i, V, Cr, Cu, Y, Mo, Rh, Pd, Ag, S
n, Sb, Te, Ba, Ta, W, Re, Au, Hg,
Pb, Bi, La, Ce, Pr, Nd, Sm, P, C
including atoms such as o, Mn, Zn, Ni, Sr, B
Good. In particular, Al, Si, Ca, Y, Ba, La, N
At least one of d, Sm, Co, Ni, and B is α-Fe.
It is preferable to include other than Co, Y, Al, Nd, S
More preferably, at least one of m is included. Co's
The content is preferably 40 atomic% or less with respect to Fe.
More preferably, it is 15-35 atomic%, Furthermore, 20
It is preferably in the range of ˜35 atomic%. Y content
Is preferably 1.5 to 12 atomic% with respect to Fe
More preferably, it is 3-10 atomic%, Furthermore, 4-9
A range of atomic% is preferred. Al content is
It is preferable that it is 1.5-30 atomic% with respect to Fe
More preferably, it is 5-20 atomic%, Furthermore, 8-15
A range of atomic% is preferred. Also these strong
Magnetic powder includes dispersants, lubricants, surfactants, antistatic
Treatment may be carried out in advance before dispersing with an agent or the like. As the ferromagnetic hexagonal ferrite, barium
Ferrite, strontium ferrite, lead ferrite
, Calcium ferrite and their various substitutions
Body, Co-substituted body and the like. Specifically, Magnet
Plumbite type barium ferrite and stront
Magnesium whose particle surface is coated with um ferrite and spinel
Toplumbite type ferrite and some spinel phase
Contained composite magnetoplumbite type barium ferrule
And strontium ferrite.
In addition to predetermined atoms, Al, Si, S, Nb, T
i, V, Cr, Cu, Y, Mo, Rh, Pd, Ag, S
n, Sb, Te, W, Re, Au, Bi, La, Ce,
Pr, Nd, P, Co, Mn, Zn, Ni, B, Ge
Any atom may be included. In general, Co-Zn, Co
-Ti, Co-Ti-Zr, Co-Ti-Zn, Ni-
Ti-Zn, Nb-Zn-Co, Sn-Zn-Co, S
What added elements, such as n-Co-Ti and Nb-Zn
Can be used. Depending on the raw material and manufacturing method,
Some contain pure products. Hexagonal plate diameter is preferred for powder size
The average plate diameter is preferably 10 to 35 nm. The ferromagnetic powder contained in the magnetic layer is obtained by the BET method.
If expressed in terms of specific surface area, usually 45-80m ² / G
The The crystallite size of ferromagnetic metal powder is usually 8-18n
m, preferably 10 to 18 nm.
More preferably, it is in the range of 11 to 17.5 nm.
Good. The average major axis length of the ferromagnetic metal powder is 30 to 150.
preferably in the range of nm, 30-100 nm
A range is more preferable. Needle shape of ferromagnetic metal powder
The ratio is preferably in the range of 3-15, 5-12
More preferably, it is the range. Saturation of ferromagnetic powder
The chemical σs is usually 100 to 200 A · m. ² / Kg (100
~ 200emu / g), 120 ~ 180A
・ M ² / Kg (120-180 emu / g)
More preferably. The plate ratio of hexagonal ferrite is
It is usually in the range of 2-20, and in the range of 2-5
More preferred. The saturation magnetization σs is usually 30 to 70 A.
・ M ² / Kg (30-70 emu / g),
40-60A ・ m ² / Kg (40-60emu / g)
A range is more preferable. Ferromagnetic powder is needed
Surface treatment with Al, Si, P or their oxides
You may give reason. The SFD of the ferromagnetic powder itself is preferably small
Moreover, 0.8 or less is preferable. That is, H of ferromagnetic powder
It is preferable to reduce the distribution of c. Especially SFD
If it is 0.8 or less, the electromagnetic conversion characteristics are good and the output is high.
In addition, the magnetization reversal is sharp and the peak shift is small.
Therefore, it is suitable for high density digital magnetic recording. Hc minutes
As a method of reducing the cloth, in ferromagnetic metal powder
Improve the particle size distribution of goethite, do not prevent sintering
Which way is there. (Carbon black blended in the magnetic layer)
In addition to the above abrasives, the constituent materials blended in the magnetic layer
In addition, carbon black may be added. Preferred carbo
As rubber, rubber furnace, rubber therma
, Black for color, acetylene black, etc.
It is. Specific surface area is 5-500m ² / G, DBP oil absorption is
10-400 ml / 100 g, average particle size is 5-300
nm, pH is 2 to 10, moisture content is 0.1 to 10% by weight,
The tap density is preferably in the range of 0.1-1 g / ml.
Yes. When using carbon black, increase the amount of ferromagnetic material.
It is preferable to use in the range of 0.1 to 30% by weight.
Yes. Carbon black prevents the magnetic layer from being charged and has a low coefficient of friction.
It has functions such as reduction, light shielding, and film strength improvement.
Depends on the carbon black used. [Nonmagnetic layer (lower layer)] Lower layer of magnetic recording medium
The structure should be limited if it is substantially non-magnetic
Although it is not a thing, it usually consists of at least a resin
Or powder such as inorganic powder or organic powder in the resin.
Examples are dispersed. The inorganic powder is preferably
Non-magnetic powder, but the lower layer is substantially non-magnetic
Magnetic powder can also be used. The lower layer is substantially non-
Being magnetic means that the electromagnetic conversion characteristics of the upper layer are substantially reduced.
It is said that the lower layer is allowed to have magnetism within the range
Meaning. (Nonmagnetic powder) As the nonmagnetic powder, metal
Oxide, metal carbonate, metal sulfate, metal nitride, metal charcoal
As appropriate from inorganic compounds such as fluorides and metal sulfides.
Is possible. Above all, small particle size distribution and functional addition
Because there are many means, such as titanium dioxide, zinc oxide,
Iron oxide and barium sulfate are preferred, titanium dioxide, α-
Iron oxide is more preferred. The average particle size of these nonmagnetic powders
Izu is preferably in the range of 0.005 to 2 μm, but necessary
Depending on the combination of non-magnetic powders with different particle sizes
Even with a single non-magnetic powder,
Can have an effect. (Abrasive used in the lower layer) Polishing in the lower layer
A diamond that contains the magnetic layer may be added.
In addition to artificial diamonds, for example, fused alumina,
Silicon carbide, chromium oxide, cerium oxide, α-iron oxide,
Corundum, artificial corundum, silicon nitride, titanium car
Bite, titanium oxide, silicon dioxide, boron nitride, zaku
Uses rock stone, emery (main components: corundum and magnetite), etc.
Can be used. Including an abrasive in the lower layer
Control the surface shape and control the protruding state of the abrasive
You can do it. (Carbon black or the like blended in the lower layer)
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 microbit.
Curse 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 for rubber
Furnace, Thermal for rubber, Black for color, AS
Tylene black or the like can be used. [Additive] For the magnetic layer and lower layer of the magnetic recording medium
Lubrication effect, antistatic effect, dispersion effect, plastic effect, etc.
Various additives having the following may be added. As an additive
Silicone oil, silicone with polar group, fat
Acid-modified silicone, fluorine-containing silicone, fluorine-containing
Alcohol, fluorine-containing ester, polyolefin, polyester
Liglycol, alkyl phosphate ester and al
Potassium metal salts, alkyl sulfates and their alkalis
Metal salt, polyphenyl ether, phenylphosphonic acid,
α-naphthyl phosphate, phenyl phosphate, diphenyl phosphorus
Acid, p-ethylbenzenephosphonic acid, phenylphosphite
Acids, aminoquinones, various silane coupling agents,
Tan coupling agent, fluorine-containing alkyl sulfate
And alkali metal salts thereof, C1-C24 monobase
Fatty acids (even if they contain unsaturated bonds, they are also branched
And these metal salts (Li, Na, K,
Cu, etc.) or monovalent, divalent, and trivalent carbon atoms of 12 to 22 carbon atoms
, Tetravalent, pentavalent, hexavalent alcohols (including unsaturated bonds)
Or may be branched), 12 to 22 carbon atoms
Alkoxy alcohol, monobasic having 10 to 24 carbon atoms
Fatty acids (even if they contain unsaturated bonds,
May be monovalent, bivalent, trivalent, tetravalent,
Pentavalent and hexavalent alcohols (even if they contain unsaturated bonds,
Which may be branched)
Fatty acid ester or difatty acid ester or tri fat
Monoester of acid ester and alkylene oxide polymer
Fatty acid esters of ethers, fatty acids of 8 to 22 carbon atoms
Mido, fatty acid amines having 8 to 22 carbon atoms, etc.
Can do. In addition, all or one of these additives
Is added at any stage of magnetic and non-magnetic coating production.
Also good. For example, when mixing with a magnetic body before the kneading step,
When adding in the kneading process with magnetic material, binder and organic solvent
When adding in the dispersion step, when adding after the dispersion,
In some cases, it is added just before coating. Depending on the purpose
After applying the magnetic layer, the additives can be applied simultaneously or sequentially.
The purpose is achieved by applying part or all of
There is a case. Depending on the purpose, calendar processing (calendar
After heat and pressure treatment with a render roll) or
After finishing, the lubricant can be applied to the surface of the magnetic layer.
The [Layer structure] Layer structure of magnetic recording medium
explain. The thickness of the magnetic recording medium support is 2 to 100.
preferably in the range of μm, in the range of 2 to 80 μm
It is more preferable that Adhesion between support and lower layer
An undercoat layer may be provided to improve the properties. Undercoat layer thickness
Is preferably in the range of 0.01 to 0.5 μm.
More preferably in the range of 0.02 to 0.5 μm.
That's right. The magnetic recording medium has a lower layer and a magnetic layer on both sides of the support.
Even a magnetic recording medium having a double-sided magnetic layer provided with a layer,
It may be a magnetic recording medium provided only on one side.
Yes. In the latter case, effects such as antistatic and curl correction are produced.
Therefore, a backcoat layer is provided on the lower layer and on the opposite side of the magnetic layer.
You may choose. This thickness is in the range of 0.1-4 μm.
Preferably in the range of 0.3 to 2.0 μm
Is more preferable. These undercoat and backcoat layers are public
Knowledge can be used. The thickness of the magnetic layer of the magnetic recording medium is determined by the magnetic field used.
Saturation magnetization of head, head gap length, recording signal
It is optimized by the bandwidth. The thickness of this magnetic layer
Is preferably in the range of 0.01 to 0.5 μm.
More preferably 0.03 to 0.3 μm,
More preferably in the range of 0.03-0.10 μm
Yes. Separate the magnetic layer into two or more layers with different magnetic properties
It does not matter if a configuration related to a known multilayer magnetic layer is used.
Yes. The thickness of the lower layer is usually in the range of 0.2 to 5 μm.
Preferably in the range of 0.3 to 3 μm, more preferably 1
More preferably, it is in the range of ˜2.5 μm. In addition,
If the lower layer is substantially non-magnetic, it will be effective
For example, a small amount of magnetic
Even if a sex body is included, it is regarded as substantially the same configuration as the present invention.
I've already mentioned that you can. Specifically, for example
The residual magnetic flux density of the layer is 0.01 Tesla (100 Gauss) or more
Lower or coercive force is less than 7.96kA / m (100Oe)
Preferably, the residual magnetic flux density and resistance
It has no magnetic force. [Support] Used for the magnetic recording medium of the present invention.
Non-magnetic supports include polyethylene terephthalate, polyethylene
Liethylene naphthalate, polyimide, polyamide
Such as sulfoxide, polysulfone and polybenzoxazole
Known film. These supports are clear
Corridor corona discharge treatment, plasma treatment, easy adhesion treatment, heat treatment
It is also possible to perform processing, dust removal processing, or the like. [Method of Manufacturing Magnetic Recording Medium] Magnetic Recording of the Present Invention
The method for producing the medium is to prepare the coating liquid for forming each layer.
Adjustment, application of coating solution to support, orientation treatment, drying, cooling,
Calendar processing, punching processing, post-curing, polishing processing, assembly
And the like. Manufacture magnetic and non-magnetic paints for magnetic recording media
The manufacturing process includes at least a kneading process, a dispersing process, and
From the mixing process provided as necessary before and after these processes
Become. Each process is divided into two or more stages.
Also good. Ferromagnetic powder, non-magnetic powder, binder,
-Bon black, abrasive, antistatic agent, lubricant, solvent
Add all ingredients at the beginning or middle of any process
It doesn't matter. Individual raw materials can be separated in two or more processes.
It may be added in portions. For example, polyurethane
Mixing process for kneading process, dispersion process, viscosity adjustment after dispersion
You may divide and add as much as possible. When kneading and dispersing magnetic paints and non-magnetic paints
In this case, various kneaders are used. For example, two rolls
Mill, three roll mill, ball mill, pebble mill, Toro
Mills, sand grinders, Segva
ri), attritors, high-speed impeller dispersers, high-speed scanners
Tone mill, high speed impact mill, disper, kneader, high
Use a high speed mixer, homogenizer, ultrasonic disperser, etc.
Can. The coating method of the coating solution is not particularly limited and is supported.
Nonmagnetic layer formed by applying nonmagnetic layer coating liquid on body
Apply the coating solution for the magnetic layer on it while it is wet.
Even with the wet-on-wet method,
After the coating solution for the magnetic layer is dried, the coating solution for the magnetic layer is applied.
A wet-on-dry method may be used. wet
・ On-wet method uses a uniform magnetic layer thickness and pin
Preventing coating defects such as holes and producing with good yield
In addition, the adhesion between the nonmagnetic layer and the magnetic layer can be improved
It is also preferable for preventing peeling of the adhesive layer. Wet on
・ In the wet coating method, the coating layer of the coating solution for the non-magnetic layer is wet.
In the wet state, the magnetic layer coating solution is applied to the non-magnetic layer.
It may be performed simultaneously or sequentially with the application of the cloth liquid. On the other hand,
The touch-on-dry method changes the interface between the magnetic and nonmagnetic layers.
Less noise, and as a result, noise can be suppressed, and S / N
Characteristics can be improved. After drying, the coating layer is subjected to a surface smoothing treatment.
I can do it. For the surface smoothing treatment, for example, super
-Calendar rolls can be used. Surface flat
By performing the lubrication treatment, it is possible to remove the solvent during drying.
The vacancies generated by the
As a result, a magnetic recording medium with high electromagnetic conversion characteristics is obtained.
be able to. Epoxy as a calendar processing roll
Resistance of Si, polyimide, polyamide, polyimide amide, etc.
Thermal plastic roll can be used
The As a condition of the calendar process, a linear pressure of 100 to 50
0 kg / cm, preferably 200 to 450 kg / cm,
The temperature of the calendar roll is 60 to 130 ° C., and further 8
It is preferable to set it as the range of 0-100 degreeC. Next, the present invention will be described in detail by way of examples and comparative examples.
The present invention will be described. In the examples, “parts” is indicated by “weight”.
Part ". Binder, paint for forming magnetic layer (magnetic paint)
And non-magnetic underlayer coating materials (non-magnetic coating materials)
The following items were prepared. The following
The amount of each component is both ferromagnetic metal powder and non-magnetic powder.
The amount per 100 parts by weight. <Synthesis of polyurethane resin PUA-1>
Equipped with a meter, a stirrer, a reflux condenser, and was previously purged with nitrogen
In a container, a polyether polyol having the composition shown in Table 1 and
Cyclohexanone 30 is a short chain diol having a cyclic structure.
% Solution in a nitrogen stream at 60 ° C. Then, with the catalyst
And then add 60 ppm dibutyltin laurate
Dissolved for 15 minutes. Next, the organic diisocyanate shown in Table 1
Add an anate compound and heat reaction for 6 hours.
Resin PUA-1 was obtained. Obtained polyurethane resin PU
A-1 hydrophilic polar group (-SO _Three Na) content is 0.2
It was 87 meq / g. <Polyurethane resins PUA-2 to PUA-
4. Synthesis of PUC-1 to PUC-3> Polyurethane resin
The chain extension shown in Table 1 is similar to the synthesis of PUA-1.
Agent, organic diisocyanate compound,
Resins PUA-2, PUA-3, PUA-4, PUC-
1, PUC-2 and PUC-3 were obtained. Each polyurethane tree
Table 1 shows the hydrophilic polar group of fat and its content. <Synthesis of polyurethane resin PUB-1>
A reactor equipped with a dynamometer, stirrer and reflux condenser
365 parts of dipic acid, 260 parts of neopentyl glycol,
As catalyst, 2% by weight of zinc acetate, 3% by weight of sodium acetate
And transesterification at 180-220 ° C for 3 hours
Followed by 220-280 ° C., 1-10 mmHg
Polyester by performing polycondensation reaction for 2 hours under reduced pressure
Polyol A was obtained. Next, the polyester polyol A is used.
As with the synthesis of polyurethane resin PUA-1,
Using a long agent and an organic diisocyanate compound,
Tan resin PUB-1 was obtained. Obtained polyurethane resin
The hydrophilic polar group content of PUB-1 is 0.824 meq /
g. <Polyurethane resins PUB-2 to PUB-
Synthesis of 7> Similar to the synthesis of polyurethane resin PUB-1
Polyester polyol A, chain elongation shown in Table 1
Using a long agent, organic diisocyanate compound,
Tan resin PUB-2, PUB-3, PUB-4, PUB
-5, PUB-6, and PUB-7 were obtained. Each polyurethane
Table 1 shows the resin hydrophilic polar groups and their contents. [Table 1] <Magnetic paint A> Hexagonal barium ferrite 100 parts Surface treatment: Al ₂ O _Three 5% by weight, SiO ₂ 2 wt% Hc: 2500 Oe Plate diameter: 25 nm Plate ratio: 3 σs: 56 emu / g Vinyl chloride copolymer (MR110: manufactured by Nippon Zeon) 7 parts Polyurethane resin (UR8200: manufactured by Toyobo) 3 parts α alumina (HIT60 : Sumitomo Chemical Co., Ltd.) 4 parts Diamond (average particle size 100 nm) 2 parts Carbon black (# 50: Asahi Carbon Co., Ltd.) 1 part Isocetyl stearate 5 parts Stearic acid 1 part Oleic acid 1 part Methyl ethyl ketone 80 parts Cyclohexanone 120 parts <Magnetic paint B> Hexagonal barium ferrite 100 parts Surface treatment: Al ₂ O _Three 5% by weight, SiO ₂ 2 wt% Hc: 2500 Oe Plate diameter: 25 nm Plate ratio: 3 σs: 56 emu / g 10 parts polyurethane resin PUA-1 α alumina (HIT60: manufactured by Sumitomo Chemical Co.) 4 parts Diamond (average particle size 100 nm) 2 parts Carbon black (# 50: manufactured by Asahi Carbon Co., Ltd.) 1 part Isocetyl stearate 5 parts Stearic acid 1 part Oleic acid 1 part Methyl ethyl ketone 80 parts Cyclohexanone 120 parts <Magnetic paint C> Ferromagnetic metal fine powder 100 parts Composition: Fe 70% Co 30% Hc: 2300 Oe Long axis length: 0.045 μm Crystal size: 120 Å s: 120 emu / g Sintering inhibitor: Al compound (Al / Fe: atomic ratio 14%), Y compound (Y / Fe: atomic ratio 7) %) Vinyl chloride copolymer (MR110: manufactured by Zeon Corporation) 10 parts Polyurethane resin (UR8200: manufactured by Toyobo Co., Ltd.) 4 parts α-alumina (HIT60: manufactured by Sumitomo Chemical Co., Ltd.) 5 parts Diamond (average particle size 0.1 μm) 1 part Carbon black (# 50: manufactured by Asahi Carbon Co., Ltd.) 1 part Phenylphosphonic acid 3 parts n-butyl stearate 3 parts butoxyethyl stearate 3 parts ethylene glycoldiolate 6 parts stearic acid 1 part oleic acid 1 part methyl ethyl ketone 140 parts cyclohexanone 200 parts <Magnetic paint D> ferromagnetic metal fine powder 100 parts Composition: Fe 70%, Co 30% Hc: 2300 Oe Long axis length: 0.045 μm Crystal size: 120 σ s: 120 emu / g Sintering inhibitor: Al compound (Al / Fe: atomic ratio 14%), Y compound (Y / Fe: atom) Ratio 7%) polyurethane resin PUA-1 10 parts α alumina (HIT60) : Sumitomo Chemical Co., Ltd.) 5 parts Diamond (average particle size 0.1 μm) 1 part Carbon black (# 50: Asahi Carbon Co., Ltd.) 1 part Phenylphosphonic acid 3 parts n-butyl stearate 3 parts Butoxyethyl stearate 3 parts Ethylene glycol diolate 6 parts Stearic acid 1 part Oleic acid 1 part Methyl ethyl ketone 140 parts Cyclohexanone 200 parts <Nonmagnetic paint a> Nonmagnetic powder α-Fe ₂ O _Three Hematite 100 parts Major axis length: 0.07μm, minor axis length: 0.014μm Specific surface area by BET method: 55m ² / G pH: 9, Surface treatment agent: Al ₂ O _Three 8% by weight Carbon black (average particle size 20 nm, Conductex SC-U: Colombian Carbon) 25 parts Vinyl chloride copolymer (MR104: Nippon Zeon) 15 parts Polyurethane resin (UR5500: Toyobo) 7 Part Phenylphosphonic acid 4 parts Isocetyl stearate 6 parts Oleic acid 1.3 parts Stearic acid 1.3 parts Methyl ethyl ketone / cyclohexanone (8/2 mixed solvent) 250 parts <Nonmagnetic paint b> Nonmagnetic powder α -Fe ₂ O _Three Hematite 100 parts Major axis length: 0.07μm, minor axis length: 0.014μm Specific surface area by BET method: 55m ² / G pH: 9, Surface treatment agent: Al ₂ O _Three 8% by weight Carbon black (average particle size 20 nm, CONDUCTEX SC-U: Colombian Carbon) 25 parts Polyurethane resin PUA-1 22 parts Phenylphosphonic acid 4 parts Isocetyl stearate 6 parts Oleic acid 1.3 parts Stearin Acid 1.3 parts Methyl ethyl ketone / cyclohexanone (8/2 mixed solvent) 250 parts <Preparation of Master Carrier> Master Carrier Group
As the plate, a Ni substrate produced by a stamper method was used.
Specifically, the range from 20 to 40 mm in the radial direction from the center of the disk.
Surrounded by a radial line with a width of 0.5 μm, the line spacing is a circle.
0.3 μm at the innermost circumferential position 20 mm in the radial direction from the center of the board
A disc-shaped Ni substrate having an uneven pattern of intervals was used.
Soft magnetic layer FeCo 30at% layer on Ni substrate at 25 ° C
Formed. The soft magnetic layer has a thickness of 200 nm and is sputtered.
The Ar sputtering pressure at the time of forming by 1.5 is 1.5 × 10 ^-Four Pa
(1.08 mTorr), input power is 2.80 W / cm
² It was. (Sample 1) Magnetic coating A and non-magnetic coating
After kneading each blend of ingredients a with kneader,
Dispersed using a mill. Obtained magnetic paint A, non-magnetic
Apply polyisocyanate to dispersion of paint a, and apply nonmagnetic layer
Add 13 parts to the cloth liquid and 4 parts to the magnetic layer coating liquid.
Add 30 parts of cyclohexanone to each of 1 μm
Filtered with a filter having an average pore size, non-magnetic layer
Adjust the coating solution for forming and magnetic layer respectively.
It was. The obtained non-magnetic layer coating solution was dried
To 1.5 μm, and immediately after that
In addition, the thickness after drying the magnetic layer coating solution will be 0.1 μm
Thus, a polyester having a thickness of 62 μm and a center line surface roughness of 3 nm.
Perform simultaneous multi-layer coating on the terephthalate support,
After drying, the temperature is 90 ° C and the linear pressure is 300 kg with a seven-stage calendar.
Processed at / cm, punched to 3.7 inch diameter
Polishing treatment was performed. The obtained medium was obtained by the previous method
Use a master carrier to record signals by magnetic transfer
It was. (Sample 2) Polyurethane of magnetic paint A
Replacing resin UR8200 with polyurethane resin PUA-1
A sample was prepared in the same manner as Sample 1 except that. (Sample 3) Vinyl chloride of magnetic paint A
Changed the amount of polymer MR110 added from 7 parts to 1.5 parts
And adding 3 parts of polyurethane resin PUA-1
Sample similar to sample 1 except for 8.5 parts
Was made. (Sample 4) Magnetic coating instead of magnetic coating A
Except for using non-magnetic paint b instead of material B and non-magnetic paint a
Prepared a sample in the same manner as Sample 1. (Samples 5 to 17) Magnetic paint and non-magnetic
Change the polyurethane resin added to the paint as shown in Table 2.
A sample was prepared in the same manner as Sample 2, except that (Sample 18) Magnetic instead of magnetic paint A
A sample was prepared in the same manner as Sample 1 except that Paint B was used.
Made. (Sample 19) Magnetic instead of magnetic paint A
A sample was prepared in the same manner as Sample 1 except that Paint C was used.
Made. (Sample 20) Magnetic instead of magnetic paint A
Non-magnetic paint b is used instead of paint D and non-magnetic paint a
A sample was prepared in the same manner as Sample 1 except for the above. (Samples 21-33) Magnetic paint and non-magnetic
Table 2 shows the polyurethane resin added to the paint
A sample was prepared in the same manner as Sample 20, except that the sample was changed.
It was. The above sample binder type, initial S /
Table 2 shows the results of quality evaluation based on the N ratio and the number of transferred sheets. table
The initial S / N ratio in 2 and the number of transferred sheets are measured as follows.
More went. (Initial S / N ratio) Samples 1 to 3 obtained
For the magnetic recording medium of No. 3
A signal having a bit length of 0.3 μm was transferred. Magnetic transfer
The later magnetic recording medium is RWA100 manufactured by US GUZIK.
Type 1 disk evaluation system and Kyodo Electronics System Co., Ltd.
M with a track width of 0.5 μm on the stand LS-90
The signal was reproduced using the R head, and the S / N value was obtained. (Quality Evaluation by Number of Transfers) Obtained Sun
For the magnetic recording media of pulls 1 to 33, the above master is manufactured.
-Transfer signals with a bit length of 0.3μm using a carrier
It was. The magnetic recording medium after magnetic transfer is manufactured by US GUZIK.
RWA1001 type disk evaluation apparatus and joint electronic system
Track width at MU Spin Co., Ltd. LS-90
Playback with 0.5μm MR head and playback output (TA
When A) is measured and 2dB lower than the starting point
Stop recording at the point and process the magnetic recording medium up to that point
I asked for the number. [Table 2] According to Table 2 above, the magnetic layer has a specific polar group.
A predetermined amount of polyurethane resin with respect to the total resin amount.
The magnetic recording medium of the present invention containing a certain amount (Samples 3 to 1)
8. Samples 20 to 33) are clear from the number of transferred sheets.
Thus, corrosion of the surface of the magnetic master carrier is prevented over a long period of time.
It was stopped. In addition, the dispersibility of the magnetic powder in the magnetic layer
Improved by polyurethane resin with polar group
Therefore, a sufficient S / N ratio can be obtained. On the other hand, polyurethane having a specific polar group
Sample 2 with a low resin content of 30% by weight, specific pole
Does not contain any polyurethane resin having a functional group
In Sample 1 and Sample 19, the number of transferred sheets is the magnetic field of the present invention.
It is half of the recording medium, and the master carrier surface is corroded.
It was thought that The magnetic recording medium of the present invention has a specific pole.
A predetermined amount of polyurethane resin having a predetermined amount of a functional group, a magnetic layer
Sample 10 and Sample 18
From this comparison, this polyurethane resin is also contained in the nonmagnetic layer.
The magnetic master carrier table for a long time by
Surface corrosion was prevented. As described above, the flexible magnet of the present invention.
The recording medium has -SO on the magnetic layer. _Three M, -OSO _Three M,-
P = O (OM) ₂ , -OP = O (OM) ₂ And -COOM
(M is a hydrogen atom, an alkali metal or an ammonium salt.
0.05) at least one polar group selected from
Polyurethane resin containing in the range of ~ 0.7 meq / g
Of 60% by weight or more of the total resin amount in the magnetic layer.
The long-term stability of the signal quality recorded on the magnetic recording medium
It became possible to plan. High polar group content
By using more than a predetermined amount of polyurethane resin, it is enough
It was possible to obtain a high S / N ratio.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shinji Saito             2-1-12 Ogimachi, Odawara-shi, Kanagawa Prefecture             Shishi Photo Film Co., Ltd. F-term (reference) 5D006 BA15 BA19 DA02 EA01

Claims (1)

1. A nonmagnetic layer and a magnetic layer on a nonmagnetic support on which a magnetic transfer master carrier having a magnetic pattern corresponding to the information to be transferred is closely attached to transfer the information. Is a flexible magnetic recording medium formed in this order,
The magnetic _{layer, -SO 3 M, -OSO 3 M} , -P = O
(OM) ₂ , -OP = O (OM) ₂ and -COOM (M represents a hydrogen atom, an alkali metal or an ammonium salt)
At least one polar group selected from 0.05 to 0.
A flexible magnetic recording medium comprising a polyurethane resin contained in a range of 7 meq / g, wherein the polyurethane resin content is 60% by weight or more of the total resin amount in the magnetic layer.