JP2003272126A - Magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic recording medium having a vinyl binder containing no vinyl chloride based resin and having excellent dispersibility, strength of a coating film and durability. <P>SOLUTION: The binder contained in a magnetic layer or a non-magnetic layer contains an acrylonitrile-styrene based resin having a polar group selected from -(O)-SO<SB>3</SB>M, -(O)PO(OM)<SB>2</SB>, -COOM, -NR<SB>1</SB>R<SB>2</SB>and -NR<SB>1</SB>R<SB>2</SB>R<SB>3</SB><SP>+</SP>and at least one polyurethane selected from (A) a polyurethane obtained from a polyol having a cyclic structure and an alkylene oxide chain, a polyol having a cyclic structure as a chain extender and an organic diisocyanate compound and having a polar group, (B) a polyurethane obtained from a polyester polyol, a chain extender and an organic diisocyanate compound and having a polar group, wherein a diol component in the polyester polyol and/or the chain extender contain a branched aliphatic diol having an alkyl group as a side chain, and (C) a polyurethane obtained from a polyol compound having a cyclic structure and a long alkyl chain and an organic diisocyanate compound and having a polar group. <P>COPYRIGHT: (C)2003,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention
Concerning magnetic recording media having conversion characteristics and running durability
The [0002] 2. Description of the Related Art Magnetic recording media include recording tapes and videos.
With tape or floppy disk
Widely used. Magnetic recording medium is ferromagnetic powder
Non-magnetically supporting a magnetic layer dispersed in a binder (binder)
Laminated on the holder. Magnetic recording media are electromagnetic conversion
High in characteristics such as performance, running durability and running performance
Need to be at a high level. That is, music recording
For audio tapes for sound playback, a higher level of
Sound reproduction capability is required. Also, attach a video tape.
In other words, the electromagnetic conversion characteristics such as excellent reproduction of the original image
It is required to be excellent. Such an excellent power
Magnetic recording media have good running characteristics while having magnetic conversion characteristics
It is required to have line durability. Durability and electricity
Binders also play an important role in improving magnetic conversion characteristics.
Is responsible. Examples of binders include vinyl chloride resin and polyester.
Polyurethane resin is widely used as a urethane resin.
Alone, because it lacks flexibility, polyurethane resin,
A highly compatible vinyl chloride resin with polyurethane resin
It is performed together. However, in recent years, the environmental load after disposal
From the title, the trend of PVC removal is increasing. Also, vinyl chloride
Resin resin generates hydrochloric acid gas, and the metal part of the drive
There is a problem of corrosion. Therefore, environmental protection and corrosion
From the viewpoint of prevention, vinyl type that does not use vinyl chloride resin
Binders have been proposed. Styrenic copolymers,
An example is an acrylic copolymer (Patent No. 26166).
38, JP-A-3-108122, etc.). However, mainly styrene and acrylic.
Vinyl binder has insufficient dispersibility,
It was a problem that it was brittle. In addition, an extremely smooth magnetic layer
For high-density recording in recent years in contact with a recording / reproducing head at high speed
Digital video tape, computer tape, high
For floppy disks with sufficient capacity, obtain sufficient durability
There was also a problem that it was not possible. Also, styrene and
Kuryl copolymer is not compatible with polyurethane
Therefore, polyurethane resin is used as a tough binder.
Solves brittleness and forms a tough coating
It was difficult. [0005] Accordingly, the present invention provides a salt.
Uses a vinyl binder that does not contain vinyl fluoride resin
Even if it is, it is excellent in dispersibility, coating film strength and durability.
An object of the present invention is to provide a magnetic recording medium. [0006] The object of the present invention is to provide support.
The magnetic layer 1 containing ferromagnetic powder and a binder is provided on the holder.
Or non-magnetic layer containing non-magnetic powder and binder and strong
A magnetic layer having a magnetic layer 2 containing a magnetic powder and a binder in this order.
A magnetic recording medium comprising the same binder as the magnetic layer 1
And a small amount of binder contained in the nonmagnetic layer and the magnetic layer 2.
At least one binder is-(O) -SO._ThreeM,-(O)
PO (OM)₂, -COOM, -NR₁R₂, -NR₁R₂
R_Three ⁺(M is a hydrogen atom, an alkali metal or an ammonium salt.
Represents R₁, R₂, R_ThreeAre hydrogen atoms or alkyls, respectively.
Acrylonite having a polar group selected from
Ril-styrene resin and (A) cyclic structure and al
Having a molecular weight of 500-5000 having a xylene oxide chain
Molecular weight 1 with cyclic structure as polyol and chain extender
Compound of 00-500 polyol and organic diisocyanate
Polyurethane having a polar group obtained from a product, (B)
Reester polyol, chain extender and organic diisocyanate
A polyurethane having a polar group obtained from
The diol component in the polyester polyol and / or
Or the chain extender has an alkyl group with 2 or more carbon atoms as a side chain
A polyurethane containing a branched aliphatic diol having, and
(C) Polyol having a cyclic structure and a long alkyl chain
Polarity obtained from compounds and organic diisocyanate compounds
At least one selected from polyurethanes having groups
According to a magnetic recording medium comprising polyurethane
Is achieved. [0007] The present invention provides a magnetic layer 1 on a support.
The magnetic recording medium, the nonmagnetic layer, and the magnetic layer 2 in this order.
And a magnetic recording medium. Has only magnetic layer 1
Magnetic recording media that have polar groups detailed below
Acrylonitrile-styrene resin and polyurethane
A binder containing is contained in the magnetic layer 1. Nonmagnetic layer and magnetism
In the case of a magnetic recording medium having a conductive layer 2, the binder is non-
Only magnetic layer, only magnetic layer 2, or nonmagnetic layer and magnetic layer
2 included. In particular, the binder is at least non-magnetic.
It is preferable that it is contained in a sex layer. In the following,
“Magnetic layer” means magnetic layer 1 and magnetic unless otherwise specified.
Means layer 2; The magnetic recording medium of the present invention will be further described below.
This will be described in detail. [Binder] In the present invention, a magnetic layer and / or a nonmagnetic layer
The binder contained in-is (O) -SO_ThreeM,-(O) P
O (OM)₂, -COOM, -NR₁R₂, -NR₁R₂R_Three
⁺(M is a hydrogen atom, an alkali metal or an ammonium salt.
R₁, R₂, R_ThreeAre each a hydrogen atom or alkyl
A polar group-containing acrylonitrile selected from the group
Styrenic resin (hereinafter “polar group-containing acrylonitrile”
-Styrene resin "," Acrylonitrile-styrene system "
Resin)), and (A) cyclic structure and alkyle
Having a molecular weight of 500 to 5,000 having an oxide chain
Molecular weight 100 having a cyclic structure as an all and chain extender
~ 500 polyols and organic diisocyanate compounds?
A polyurethane having a polar group obtained from (B)
Steal polyol, chain extender and organic diisocyanate
It is a polyurethane having a polar group obtained from a compound.
Diol component in polyester polyol and / or
The chain extender has an alkyl group with 2 or more carbon atoms as a side chain
Polyurethanes containing branched aliphatic diols, and
(C) Polyol having a cyclic structure and a long alkyl chain
Polarity obtained from compounds and organic diisocyanate compounds
At least one selected from polyurethanes having groups
It is characterized by containing polyurethane. In the present invention
Polar group-containing acrylonitrile-styrene tree used
Fat is a polymer that does not substantially contain halogen elements such as chlorine.
- Therefore, vinyl chloride, vinylidene chloride, etc.
In polymerized, halogen-containing vinyl polymers
Corrosion caused by dehydrochlorination gas and environmental impact after disposal
There is no problem. Furthermore, the polar group-containing acrylonitrile
-Styrenic resin has the specific structure described below.
These polyurethanes have excellent compatibility with polyurethane.
Extremely tough and flexible coating when used in combination with Tan
Can be formed. [Polar group-containing acrylonitrile-styrene
Resin] In the present invention, the magnetic layer and / or the nonmagnetic layer
The binders included are-(O) -SO_ThreeM,-(O) PO
(OM)₂, -COOM, -NR₁R₂, -NR₁R₂R_Three ⁺
(M represents a hydrogen atom, an alkali metal or an ammonium salt.
And R₁, R₂, R_ThreeAre each a hydrogen atom or an alkyl group
Acrylo containing a hydrophilic polar group selected from
Nitrile-styrene resin is included. Acrylonitrile
By containing the polar group in the styrenic resin,
High binding power of binder on the surface of magnetic and non-magnetic powders
That is, dispersibility can be improved. As a polar group
Is-(O) -SO_ThreeM,-(O) PO (OM)₂, -C
OOM, -NR₁R₂, -NR₁R₂R_Three ⁺(M is a hydrogen atom,
Represents an alkali metal or ammonium salt, R₁, R₂, R
_ThreeEach represents a hydrogen atom or an alkyl group)
Among them,-(O) -SO_ThreeM and-(O) PO (O
M)₂Is particularly preferable because of its excellent dispersibility. Polar group included
The amount is preferably 0.001-1 meq / g.
More preferably 0.01 to 0.5 meq / g.
That's right. If the polar group content is 0.001 meq / g or more
Dispersibility can be improved, and 1 meq / g or less
If so, the viscosity of the coating solution is low and the dispersibility is also good. Ma
Two or more polar groups to be introduced may be mixed. In the present invention, a polar group-containing acrylonite
The molecular weight of the ril-styrene copolymer is 5 in terms of number average molecular weight.
000 to 200000, preferably 1000
More preferably, it is 0-100,000. Number average
If the weight is 5000 or more, physical strength such as coating strength
This improves the durability of magnetic tapes and the like. Number average
If the amount is 200,000 or less, the paint viscosity is low and work
Good dispersibility, easy handling, and further improved dispersibility
The The polar group-containing acrylonitrile-styrene resin
Has a glass transition temperature (Tg) of 50 ° C to 130 ° C.
It is preferable. If Tg is 50 ° C. or higher, the durability is
High and does not cause adhesive failure. Tg is 130 ° C or higher
Below, calendar formability is high and surface smoothness is high
A magnetic layer is obtained and the electromagnetic conversion characteristics are good. In the above acrylonitrile-styrene resin
The composition ratio of acrylonitrile is 1-6 in the resin.
It is preferably 0% by mass, more preferably 5-4.
0 mass%, particularly preferably 10-30 mass%
The On the other hand, the composition ratio of styrene is 10 to 95 in the resin.
It is preferable that it is a quantity%, More preferably, it is 30-85.
% By weight, particularly preferably 40 to 70% by weight.
The Polarity to acrylonitrile-styrene resin
As a method for introducing a group, a polar group-containing vinyl monomer
The method of copolymerizing can be used. Contains polar groups
Examples of vinyl monomers that can be used include 2-acrylic
Mid-2-methylpropane sulfonic acid, vinyl sulfone
Acid, (meth) acryl sulfonic acid, p-styrene sulfo
Unsaturated hydrocarbon sulfonic acids such as acids and their salts,
(Meth) acrylic acid sulfoethyl ester, (meth) a
(Meth) acrylic such as sulfopropyl ester of crylic acid
Sulfoalkyl esters of acids and their salts, (me
T) Acrylic acid-2-ethyl sulfate, 3-allyloxy-2
-Hydroxypropanesulfuric acid and their salts, (meth)
Acrylic acid-2-propyl phosphate, (meth) acrylic acid
2-ethyl phosphate, (meth) acrylic acid-2-phosphate
Propyl, 3-allyloxy-2-hydroxypropane
Sphonic acid, vinylphosphonic acid, 2-acrylamide-2
-Methylpropanephosphonic acid, (meth) acrylic acid-2
-Propyl phosphonate, (meth) acrylic acid-2-phos
Ethyl fonate, (meth) acrylic acid, and salts thereof,
Maleic acid and salts thereof, N, N-dimethylamino
Nopropylacrylamide, N, N-dimethylaminome
Til (meth) acrylate, N, N-dimethylamino
Til (meth) acrylate, N, N-diethylamino
Til (meth) acrylate, N, N-diethylamino
Til (meth) acrylate, N, N-dimethylaminop
Lopyr (meth) acrylate, (meth) acryloylmo
Ruphorin, morpholinoethyl (meth) acrylate, etc.
(Meth) acrylates and the like can be used. this
Even if only one kind of these polar group-containing vinyl monomers is used, 2
More than one type may be used in combination. The method for introducing a polar group is other than the above.
As a method of using a polar group-containing radical polymerization initiator
Method of copolymerizing monomer mixture, having polar group at one end
The monomer mixture in the presence of a chain transfer agent
A method may be used. Polar group-containing radical polymerization initiator
For example, ammonium persulfate, potassium persulfate
And sodium persulfate. These raji
The amount of cal polymerization initiator used is 1 to 1 with respect to the total amount of monomers.
What is necessary is just 10 mass%, Preferably it is 1-5 mass%
The Chain transfer agents having the above polar group at one end are heavy.
Chain transfer is possible in the reaction and a polar group is attached to one end.
It is not particularly limited as long as it has, for example, at one end
Mercapto compounds having a polar group and diphenylpicryl
And hydrazine. As a mercapto compound
Is preferably 2-mercaptoethanesulfonic acid
(Salt), 3-mercapto-1,2 propanediol,
Lucaptoacetic acid (salt), 2-mercapto-5-benzimi
Dazole sulfonic acid (salt), 3-mercapto-2-buta
Nord, 2-mercaptobutanol, 3-mercapto-
2-propanol, N (2-mercaptopropyl) glyce
Syn, ammonium thioglycolate or β-mercap
Toethylamine hydrochloride and the like can be used. these
One or two chain transfer agents having a polar group at one end of
A combination of the above can be used. Especially preferred
The chain transfer agent having a polar group at one end used is polar
It is a strong 2-mercaptoethanesulfonic acid (salt).
The amount of these chain transfer agents used is based on the total amount of monomers.
It may be 0.1 to 10% by mass, preferably 0.2.
˜5 mass%. As yet another method, no polar group is contained.
Acrylonitrile-styrene resin is polymerized by polymer reaction
A sex group can be added and introduced. For example, specifically
Is -SO_ThreeWhen M is introduced, the glycidyl group is used first.
Polymerizable compound into acrylonitrile-styrene resin
After copolymerization, at the same time as copolymerization or after obtaining a copolymer
-SO_ThreeReacting with compounds having M, polar groups
Can be introduced. To introduce a glycidyl group
As a copolymerizable compound, glycidyl (meth) a
Acrylate, glycidyl vinyl ether, etc.,
These may be used alone or in combination of two or more. In the present invention, the above-mentioned polar group-containing acrylo
Monomers other than the above are used in combination with the nitrile-styrene resin.
Polymerization may be performed. As a copolymerizable monomer,
Le (meth) acrylate, ethyl (meth) acrelane
, Propyl (meth) acrylate, butyl (meth) a
Acrylate, isobutyl (meth) acrylate, pliers
Lu (meth) acrylate, hexyl (meth) acrelane
, Octyl (meth) acrylate, 2-ethylhexyl
Le (meth) acrylate, lauryl (meth) acrelan
, Stearyl (meth) acrylate, cyclohexyl
Alkyl (meth) acrylates such as (meth) acrylates
Tomonomer, benzyl (meth) acrylate, phenoxy
Siethyl (meth) acrylate, phenoxypolyethylene
Glycol (meth) acrylate, nonylphenol
Ethylene oxide adduct (meth) acrylate, etc.
(Meth) acrylate monomer with aromatic ring, α-me
Chile styrene, p-methyl styrene, p-ethyl styrene
, Styrene derivatives such as pt-butyl styrene,
Toxiethyl (meth) acrylate, Butoxyethyl
Alkoxyalkyl such as (meth) acrylate
) Acrylates, glycidyl (meth) acrylate
, Allyl glycidyl ether, methyl vinyl ether
, Ethyl vinyl ether, isobutyl vinyl ether
, N-butyl vinyl ether, 2-ethylhexylbi
Nyl ether, n-octyl vinyl ether, lauryl
Vinyl ether, cetyl vinyl ether, stearyl vinyl
Alkyl vinyl ethers such as nyl ether, vinyl acetate
Nyl, vinyl esters such as vinyl propionate,
Mention may be made of (anhydrous) maleic acid. The polar group-containing acrylonitrile-styrene
It is also preferable to copolymerize a hydroxyl group-containing monomer with a vinyl resin.
Good. Examples of hydroxyl-containing monomers include hydroxyethyl
Lu (meth) acrylate, hydroxypropyl (meth)
Acrylate, polyethylene glycol mono (meth) a
Chryrate, polypropylene glycol mono (meth) a
Acrylate, polyethylene glycol polypropylene
Recall mono (meth) acrylate, glycerol mono
(Meth) acrylate, 3-chloro-2-hydroxyl
Hydroxyalkyl such as lopyr (meth) acrylate
(Meth) acrylates, hydroxyethyl vinyl ether
Tellurium, hydroxypropyl vinyl ether, hydroxy
Vinyl ethers such as butyl vinyl ether, hydroxy
Cyethyl mono (meth) allyl ether, hydroxypro
Pyrmono (meth) allyl ether, hydroxybutyl
(Meth) allyl ether, diethylene glycol mono
(Meth) allyl ether, dipropylene glycol mono
(Meth) allyl ether, glycerin mono (meth) ant
Ether, 3-chloro-2-hydroxypropyl (medium
(Ta) (Meth) allyl ethers such as allyl ether,
(Meth) allyl alcohol etc. are mentioned. Contains polar groups
Acrylonitrile-styrene resin with vinyl alcohol
In this case, for example, vinyl acetate
Saponification reaction with caustic in a solvent
It can be introduced by responding. Monomer having a hydroxyl group
The amount of is preferably 5 to 30% by mass in the total monomers.
That's right. If the amount of monomer having a hydroxyl group is within the above range
Therefore, the curability when using an isocyanate curing agent is improved.
And durability can be improved. The above polymerizable compounds and chain transfer agent are included.
In order to polymerize the polymerization reaction system, a known polymerization method, for example,
For example, suspension polymerization, emulsion polymerization, solution polymerization, etc. can be used.
Yes. The polymerization conditions are the compounds that can be used and the start of polymerization.
Generally varies depending on the type of agent and chain transfer agent.
In the clave, the temperature is about 50-90 ° C, gauge pressure
Is about 4.0 to 1.0 MPa, and the time is about 5 to 30 hours.
It is preferable to polymerize under the polymerization conditions. Polymerization reaction
The reaction control can be performed in an inert gas atmosphere.
It is preferable in terms of safety. Examples of such gases include
Nitrogen, argon and the like, preferably economical
Nitrogen is used from the point. In the polymerization, the above polymerization reaction
In addition to the above-mentioned components, other components may be added to the reaction system. So
Examples of such components include emulsifiers, electrolytes, and polymers.
Examples include protective colloids. In the present invention, a magnetic layer and / or a non-magnetic layer
The binder contained in the layer is the above polar group-containing acrylonitrile.
Along with ru-styrene resin, (A) cyclic structure and alkyl
A polymer having a molecular weight of 500 to 5000 having a lenoxide chain.
Molecular weight of 10 having a cyclic structure as Liol and chain extender
0-500 polyols and organic diisocyanate compounds
Polyurethane having a polar group obtained from
Ributane A ”), (B) Polyester Polyol
It is obtained from a chain extender and an organic diisocyanate compound.
Polyurethane having a polar group, which is polyester
The diol component and / or chain extender in the polyol is carbon
Branched aliphatic di having an alkyl group of 2 or more as a side chain
Polyurethane containing all (hereinafter, “Polyurethane B”)
And (C) having a cyclic structure and a long alkyl chain
Polyol compounds and organic diisocyanate compounds
Polyurethane having a polar group (hereinafter referred to as “poly
Urethane C ”))
It contains a urethane. Polyurethane
Is extremely strong and against ferromagnetic and non-magnetic powders
Adsorption power is high. Thus, a bond containing the above polyurethane
By using the agent, dispersibility and mechanical strength are high,
A magnetic recording medium having excellent durability can be obtained. Furthermore,
Polyurethanes A to C are the polar group-containing acrylonitrile.
Poly-styrene resin has excellent compatibility with poly
Urethanes A to C and the above polar group-containing acrylonitrile
By using in combination with a styrene resin, it is extremely tough and
A flexible coating film can be formed. Polyurethane
A to C can be used alone or in combination.
You can also. [Polyurethane A] Odor of polyurethane A
Molecules having a cyclic structure and an alkylene oxide chain
A quantity of 500-5000 polyol has a cyclic structure.
By addition reaction of diol and alkylene oxide
Can be obtained. As a diol having a cyclic structure
For example, bisphenol A, hydrogenated bisphenol
A, bisphenol S, hydrogenated bisphenol S, bis
Phenol P, hydrogenated bisphenol P, tricyclode
Kandimethanol, cyclohexanedimethanol, siku
Rhohexanediol, 5,5 '-(1-methylethylide
) Bis- (1,1'-bicyclohexyl) 2-o
4,4 '-(1-methylethylidene) bis-2methyl
Lucyclohexanol, 5,5 '-(1,1'-cyclo
Hexylidene) bis- (1,1'bicyclohexyl) 2
-Ol, 5,5 '-(1,1'-cyclohexylmethyle
) Bis- (1,1'bicyclohexyl) 2-ol,
Hydrogenated terpene diphenol, diphenylbisphenol
A, diphenyl bisphenol S, diphenyl bisphenol
Nord P, 9,9-bis- (4-hydroxyphenyl)
Fluorene, 4,4 '-(3-methylethylidene) bis
(2-cyclohexyl-5-methylphenol), 4,
4 '-(3-methylethylidene (bis (2-phenyl-
5-methylcyclohexanol), 4,4 '-(1-Fe
Nylethylidene) bis (2-phenol), 4,4'-
Cyclohexylidenebis (2-methylphenol), te
Diols such as rupened diphenol can be used
The To these diols having a cyclic structure,
Alkylene oxides such as side and propylene oxide
The polyol obtained by adding the
Having a molecular weight of 500-5000 having a xylene oxide chain
It can be used as a polyol. Above all, Bisuf
Enol A propylene oxide adduct, hydrogenated bis
Phenol A polypropylene oxide adduct, minutes
It is preferable to use the one with a mass of 500-5000
Yes. If the molecular weight is 500 or more, the urethane group concentration is low.
Therefore, if the solvent solubility is high and it is 5000 or less, the coating strength is high.
High degree of durability and good durability. In polyurethane A, as a chain extender
A polymer having a cyclic structure and having a molecular weight of 100 to 500
As a diol, a diol having the above cyclic structure
And ethylene oxide in the molecular weight range of 100-500.
Alkylene oxide such as propylene oxide
Added ones can be used. Above all, hydrogenation
Propile of sphenol A and hydrogenated bisphenol A
It is preferable to use an oxide adduct. [Polyurethane B] Raw material of polyurethane B
As a polyester polyol to become dibasic acid or
Obtained by polycondensation of the dialkyl ester and glycol.
Polyester polyol having a molecular weight of 500 to 5000
Is preferably used. Raw material for polyester polyol
The dibasic acid used as a material is an aliphatic dibasic acid
For example, succinic acid, adipic acid, azerai
Acid, sebacic acid, malonic acid, glutaric acid, pimeline
It is possible to use aliphatic dibasic acids such as acid and suberic acid.
Yes. Of these, succinic acid, adipic acid,
Vacic acid. All dibasic acids of polyester polyol
Among the ingredients, the content of aliphatic dibasic acid is 70 mol% or more
Preferably there is. If it is 70 mol% or more, it is substantially
The dibasic acid component having a cyclic structure such as aromatic dibasic acid
Less, it has high solvent solubility and good dispersibility. For polyester polyol or chain extender
Branch having an alkyl group having 2 or more carbon atoms as a side chain
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
-Propanediol, 3-ethyl-3-butyl-1,5
-Pentanediol, 2-ethyl-2-propyl-1,
3-propanediol, 3-ethyl-3-propyl-
1,5-pentanediol, 2,2-dibutyl-1,3
-Propanediol, 3,3-dibutyl-1,5-pen
Tandiol, 2,2-dipropyl-1,3-propane
Diol, 3,3-dipropyl-1,5-pentanedio
2-butyl-2-propyl-1,3-propanedi
All, 3-butyl-3-propyl-1,5-pentane
Diol, 2-ethyl-1,3-propanediol, 2
-Propyl-1,3-propanediol, 2-butyl-
1,3-propanediol, 3-ethyl-1,5-pen
Tandiol, 3-propyl-1,5-pentanedioe
, 3-butyl-1,5-pentanediol, 3-octane
Til-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
All, 5-butyl-1,9-nonanediol, etc. are used
In particular, 2-ethyl-2-butyl-1,3-pro
Pandiol, 2,2-diethyl-1,3-propanedi
It is preferable to use all. In polyurethane resin
The content of the branched aliphatic diol is 5 to 30% by mass.
Preferably, it is 10 to 20% by mass.
Is preferred. For polyester polyol or chain extender
Other diols that can have a branched fat
Group diols and alicyclic diols are preferred, for example, 2,
2-dimethyl-1,3-propanediol, 3-methyl
-1,5-pentanediol, 3,3-dimethyl-1,
5-pentanediol, cyclohexanedimethanol,
Cyclohexanediol, hydrogenated bisphenol A, water
For example, elemental bisphenol F can be used. [Polyurethane C] Polyurethane C is a ring.
A polyol compound having a chain structure and a long alkyl chain, and
Polyurethanes obtained from organic diisocyanate compounds
It is. Here, a long-chain alkyl chain is a C2-C18
An alkyl chain. Has cyclic structure and long alkyl chain
The polyol to be used is one having a molecular weight of 500 to 1,000.
Is preferably used. If the molecular weight is 500 or more
For example, urethane content is substantially low and urethane
Since the group concentration decreases, the solvent solubility is good and the molecule
If the amount is 1000 or less, the coating strength can be increased.
Yes. The above polyol is 5 mass in the polyurethane resin.
% Or more is preferably contained, and further 10 to 40 masses.
% Is preferably included. Polyurethane C is a polyol compound.
From benzene, naphthalene and cyclohexane rings
Selected cyclic structure and at least two carbon atoms 1-18
An alkylene group of 2 or 2 having 2 to 18 carbon atoms
It is preferable to include a diol component having an alkylene group
Yes. Polyurethane C is an alkyl chain having more than 18 carbon atoms
Compared to polyurethane with polyol having
Increase the weight fraction of the socyanate component,
Can be increased. This allows urethane-bonded molecules
To increase the mechanical interaction of polyurethane.
Is possible. Also, benzene ring, naphthalene ring,
Because it has a cyclic structure such as clohexanone ring,
It has the feature that the strength can be increased. Ingredients
Physically, from the formula 1 or 2 as a polyol compound
There may be mentioned at least one selected. [0026] [Chemical 1] Further, as the diol compound, those represented by the formulas 3 to 6
At least one selected from the group. [Chemical 2] In particular, these cyclic structures and long-chain alkyls
As a polyol compound having a chain,
Is preferred. Dimer diol is obtained from dimer acid
It has a chemical structure of the following formula 7. [Chemical 3] Dimer diol has a molecular weight of 537.
Polyureta using polyols with more than 18 carbon atoms
Increase the weight fraction of diisocyanate component compared to
Urethane bond can be increased. This
Increase the molecular interaction of tan bonds and increase the dynamics of polyurethane
The strength can be increased. In addition, Daimer Oh
Because ru has a cyclohexane ring, which is a cyclic structure
Can also increase the mechanical strength. Dimer diol is an unsaturated compound having 18 carbon atoms.
After dimer acid is a dimer of Japanese aliphatic carboxylic acid
The unsaturated bond and carboxylic acid are reduced by hydrogenation,
It was obtained by distillation purification. Henkel, Toa Gosei
A commercially available product can be used. Dimer diol is the basis of saturated hydrocarbons.
It has a skeleton, no unsaturated bond, and an intermediate in the molecule.
It does not have a linking group such as a steal bond or an ether bond. Obedience
It consists of this diol and diisocyanate compound
Polyurethane has an ester bond and an ether bond
Absent. This means degradation and decomposition under high temperature and high humidity.
Makes it difficult to receive and greatly improves the long-term storage stability of magnetic recording media
Let Especially when polyester polyol is used
Hydrolysis of the ester bond moiety or polyether polyol
There is no problem of thermal decomposition of ether bond when using
Good. Also, dimer diol has long alkyl branch side
Solvent solubility with two chains and a bent molecular structure
Is expensive. This allows the magnetic material to be
When dispersed, the spread of molecular chains adsorbed on the magnetic material is greatly increased.
A crisp structure (conformation)
Dispersibility can be improved because it is rinsed. In addition, da
Entanglement of polymer chain due to bent structure of imerdiol
Interactions between entanglement and urethane groups by intermolecular hydrogen bonding
High mechanical strength, that is, high elastic modulus and large elongation at break
Can be balanced. As a result, the coating strength
Can enhance the durability. Also dima
-Polyurethane using diol is a conventional polyester
Ester-based compared to polyurethane and polyether polyurethane
There is a feature that the lubricant is easily compatible. Used in the above polyurethanes A to C
There are no particular restrictions on the organic diisocyanate compound, and
Those commonly used can be used, for example,
Xamethylene diisocyanate, tolidine diisocyanate
, Isophorone diisocyanate, 1,3-xylile
Diisocyanate, 1,4-xylylene diisocyanate
Cyclohexane diisocyanate, toluidine dii
Socyanate, 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
Range isocyanate and the like can be used. The polyurethanes A to C contain polar groups.
To do. By containing a polar group, ferromagnetic powder and non-magnetic
Increases the adsorptivity of binder to porous powder and improves dispersibility
Can be made. Pole included in polyurethane A to C
The functional group is the acrylonitrile-styrene resin described above.
It is preferable that it is the same polar group as what was introduce | transduced into.
Polyurethanes with polar groups are polyesters with polar groups.
Polar groups such as steal polyol and polyether polyol
Containing polyol and polyester poly not having polar groups
Polyols such as all and polyether polyols and diy
Can be made from socyanate, for example, divalent
Diol containing polar group of alcohol or dibasic acid
Alternatively, it can be produced by changing to a polar group-containing dibasic acid.
Yes. The polar group-containing polyol is the main polyol of the following polyols:
The chain or side chain has a polar group represented by the general formula shown above.
To do. In addition, as a chain extender, it is public
Known substances, polyols, aliphatic polyamines, cycloaliphatic poly
Amines, aromatic polyamines and the like can be used. Above all
A polyhydric alcohol having a molecular weight of 50 to 500 is preferred. Molecular weight
Is 50 or more, the coating film strength is high and the durability is excellent.
If it is 00 or less, the Tg of the coating film is high, the coating film strength is high, and resistance
Excellent durability. As the polyol, bisphenol A,
Hydrogenated bisphenol A, bisphenol S, bisphenol
Nord P and their ethylene oxides, propyleneoxy
Adduct, cyclohexanedimethanol, cyclohexa
Diol, hydroquinone, bis (2-hydroxy ether
Til) tetrabromobisphenol A, bis (2-hydride)
Roxyethyl) tetrabromobisphenol S, bis
(2-Hydroxyethyl) tetramethylbisphenol
S, bis (2-hydroxyethyl) diphenylbisphe
Nord S, bis (2-hydroxyethyl) diphenylbi
Phenol, bis (2-hydroxyethyl) thiodiphe
Nord, bis (2-hydroxyethyl) bisphenol
F, biphenol, bisphenol fluorene, bisph
Rings such as enol full orange hydroxyethyl ether
It is preferable to use a short-chain diol having a shape structure,
Bisphenol A, hydrogenated bisphenol A, bisphenol
Nord S, bisphenol P and their ethylene oxide
, Propylene oxide adduct, cyclohexane dimethano
Aromatic and alicyclic
More preferably, a diol is used. Of the polyurethanes A to C used in the present invention
The average molecular weight is preferably 5,000 to 100,000.
Furthermore, it is preferable that it is 10,000 to 50,000.
That's right. If the average molecular weight is 5000 or more, such as coating strength
The physical strength is improved and the durability of the magnetic recording medium is excellent.
If the average molecular weight is 100,000 or less, the solvent solubility is
High dispersibility, and paint viscosity at a given concentration
Is excellent in workability and easy to handle. Polyurethanes A to C used in the present invention
Preferably has an OH group.
Having OH group is preferred from the viewpoint of curability and durability
And the number should be 2 to 40 per molecule.
Preferably, more preferably 3 to 20 per molecule
It is preferable that [Other binders] In the present invention,
There are no particular restrictions on the resin that can be used in combination with the binder.
Known thermoplastic resins used as binders,
Uses thermosetting resin, reactive resin and mixtures of these
can do. Glass transition temperature as a thermoplastic resin
Degree is -100 to 150 ° C, number average molecular weight is 1000 to 2
00000, preferably 10,000 to 100,000
Can be used. Specifically vinyl butyral,
As a structural unit, vinyl acetal, vinyl ether, etc.
Examples thereof include copolymers and various rubber resins. Also heat
Examples of curable resins or reactive resins include phenolic resins.
Fat, phenoxy resin, epoxy resin, urea resin, melami
Resin, alkyd resin, formaldehyde resin, silicon
Resin, epoxy-polyamide resin, polyester resin
And a mixture of fat and isocyanate prepolymer.
The In the present invention, the resin component and the curing agent are combined.
The weight of the meter (i.e., the binder) is the magnetic layer and / or non-magnetic
5 to 100 parts of ferromagnetic or nonmagnetic powder
It is preferable to be within the range of ˜50 parts. In particular,
Magnetic layer by setting the content within the range of 7 to 45 parts
Or a phenomenon such as the glossiness of the surface of the nonmagnetic layer increases,
Good dispersion of ferromagnetic or non-magnetic powder
I understand. Furthermore, the content is within the range of 10 to 40 parts.
By setting, the electromagnetic conversion characteristics are remarkably improved.
The If the content is less than 5 parts, ferromagnetic powder or non-magnetic
Powder does not bind and powder falls off, and more than 50 parts
Even if a large amount is added, the dispersion state of ferromagnetic powder or non-magnetic powder
No further improvement, and the magnetic layer has a low filling degree of ferromagnetic powder.
The electromagnetic conversion characteristics may be lowered. [Curing Agent] In the present invention, a curing agent is used as a curing agent.
A reisocyanate compound or the like can be used. Po
Examples of reisocyanate compounds include tolylene diiso
Between 3 moles of cyanate and 1 mole of trimethylolpropane.
Reactive organisms (eg, Desmodur L-75 (Bayer
Made)), xylylene diisocyanate or hexamethyle
3 moles of diisocyanate such as diisocyanate
The reaction product with 1 mol of dimethylolpropane, hexame
Addition of burette with 3 moles of diisocyanate
Compound, tolylene diisocyanate 5 mol isocyanurate
Compound, 3 moles of tolylene diisocyanate and hexa
Methylene diisocyanate with 2 moles of isocyanurate
Compounds, isophorone diisocyanate and dipheny
To mention polymers of methane diisocyanate.
Yes. For the magnetic layer, 10-50% by weight in the binder.
The polyisocyanate compound is contained within the range of
And more preferably in the range of 20 to 40% by weight.
It is a circle. In addition, when curing by electron beam irradiation
Reactive double bonds such as urethane acrylate
Can be used. In the present invention, the ferromagnetism contained in the magnetic layer
The powder can be ferromagnetic metal powder or ferromagnetic hexagonal ferrite.
Yite powder can be used. [Ferromagnetic metal powder] Ferromagnetic metal powder used in the present invention
As the main component of Fe (including alloys)
If it is, it will not specifically limit, but the strength which has alpha-Fe as a main component
Magnetic alloy powder is preferred. These ferromagnetic metal powders
In addition to predetermined atoms, Al, Si, S, Sc, Ca, Ti,
V, Cr, Cu, Y, Mo, Rh, Pd, Ag, Sn,
Sb, Te, Ba, Ta, W, Re, Au, Hg, P
b, Bi, La, Ce, Pr, Nd, P, Co, Mn,
It may contain atoms such as Zn, Ni, Sr, B, etc.
Yes. Al, Si, Ca, Y, Ba, La, Nd, Co,
At least one of Ni and B is included in addition to α-Fe
In particular, those containing Co, Al, Y
preferable. More specifically, Co is 10% with respect to Fe.
~ 40 atom%, Al is 2 to 20 atom%, Y is 1 to 15 atoms
Those containing a child percentage are preferred. These ferromagnetic metal powders include the components described later.
Before dispersion with powder, lubricant, surfactant, antistatic agent, etc.
Processing may be performed in advance. Ferromagnetic gold
The genus powder contains a small amount of water, hydroxide or oxide.
Anyway. The moisture content of the ferromagnetic metal powder is 0.01
It is preferable to set it to -2%. Strong depending on the type of binder
It is preferable to optimize the moisture content of the magnetic powder. Ferromagnetic
The major axis length of the metal powder is preferably 25 to 200 nm
More preferably, the thickness is 35 to 100 nm.
It is. The crystallite size is 80 to 200 mm, preferably 9
0 to 180 mm, particularly preferably 100 to 160 n.
m is suitable. Long axis length is transmission electron microscope
Taking a mirror photo, the short axis length of the ferromagnetic metal powder from the photo
And image analysis device KARLZ
Transmission electron micrograph tray with IBS IBASSI
It is required to use the method of reading by reading. In addition, this departure
In Ming, the crystallite size is determined by the X-ray diffractometer (Rigaku Denki)
RINT2000 series), and the source CuK
Diffraction under conditions of α1, tube voltage 50kV, tube current 300mA
The average obtained by the Scherrer method from the half width of the peak
Average values were used. In the present invention, the strong magnet used in the magnetic layer
Specific surface area (S_BET) Is 30m²/
g or more 80m²/ G is preferable. further
38-55m²/ G is preferred. This is good
Both surface properties and low noise can be achieved. Ferromagnetic powder
pH can be optimized by combination with binder used
preferable. The range is 4-12, preferably 7-
10. Ferromagnetic powder can be Al, Si, P as required
Alternatively, these oxides may be used for surface treatment.
Absent. The amount is 0.1-10% with respect to the ferromagnetic powder
When surface treatment is applied, the adsorption of lubricants such as fatty acids is 100m.
g / m²The following is preferable. Soluble in ferromagnetic powder
Contains inorganic ions such as Na, Ca, Fe, Ni, Sr
In some cases, if it is 200ppm or less, it will affect the characteristics.
It is rare to give. Also used in the present invention
Ferromagnetic powder preferably has fewer vacancies and its value is 2
0% by volume or less, more preferably 5% by volume or less.
Is appropriate. The shape of the particle support shown above
Needle-like, granular, rice-grained rice
It can be either plate-shaped or plate-shaped, but it is especially acicular ferromagnetic
Preference is given to using powder. Of acicular ferromagnetic metal powder
In this case, the acicular ratio is preferably 4 or more and 12 or less,
More preferably, it is 5 or more and 12 or less.
The The coercive force Hc of the ferromagnetic metal powder is preferably
159-239 kA / m (2000-3000 Oe)
More preferably 167 to 231 kA / m (210
0 to 2900 Oe), and saturation flux
The density is preferably 0.1 to 0.3 T (1000 to 300
0G), more preferably 0.16 to 0.28T.
(1600-2800G) is appropriate. σ
s is preferably 140 to 170 A · m²/ Kg (140
-170 emu / g), more preferably 145-160
Am²/ Kg (145-160 emu / g)
Is appropriate. [Ferromagnetic hexagonal ferrite powder] In the present invention,
As a ferromagnetic powder, ferromagnetic hexagonal ferrite powder
You can also use the powder. Increase track density especially
Therefore, when reproducing with a magnetoresistive head, low noise is required.
The plate diameter is preferably 40 nm or less, but not 5 nm
If it is full, stable magnetization cannot be expected due to thermal fluctuation. 200n
Above m, the noise is high, both for high density magnetic recording
Not suitable. The plate ratio (plate diameter / plate thickness) is 1 to 15
Is desirable, preferably 1-7
The When the plate ratio is small, the filling property in the magnetic layer is high, which is preferable.
However, sufficient orientation cannot be obtained. Greater than 15
Noise increases due to stacking between particles. this
The specific surface area of the particle size range by BET method is 10-20
0m²/ G. Specific surface area is roughly determined from particle plate diameter and plate thickness
Sign the arithmetic value of. Distribution of particle plate diameter and plate thickness is normal
Narrower is preferable. Particle TEM copy is difficult to quantify
Comparison can be made by measuring 500 particles at random.
In many cases, the distribution is not a normal distribution.
Σ / average size = 0.1
~ 2.0. To sharpen the particle size distribution
Make the particle generation reaction system as uniform as possible
In some cases, the particles are subjected to a distribution improvement treatment. And
For example, a method of selectively dissolving ultrafine particles in an acid solution
Are known. In general, the coercive force Hc is 39.8 to 398 k.
Ferromagnetic hexagons up to A / m (500-5000 Oe)
Crystalline ferrite powder can be prepared. Higher Hc is higher
It is advantageous for density recording, but limited by the capacity of the recording head.
The Ferromagnetic hexagonal ferrite powder used in the present invention
Hc of 159 to 239 kA / m (2000 to 300
0 Oe), preferably 175 to 223 kA /
m (2200 to 2800 Oe) is appropriate.
The When the saturation magnetization of the head exceeds 1.4 Tesler
Should be 159 kA / m (2000 Oe) or more
preferable. Hc is the particle size (plate diameter / plate thickness) and contained elements
Type and amount, element substitution sites, particle generation reaction conditions, etc.
More control. The saturation magnetization σs is 40 to 80 A · m²/
kg (40-80 emu / g) is appropriate
The σs is preferably higher, but smaller as it becomes finer
Tend to be. Magnetoplanbite for σs improvement
Containing spinel ferrite with ferrite, containing
Selection of element types and addition amounts is well known. Also
It is also possible to use W-type hexagonal ferrite. When dispersing ferromagnetic hexagonal ferrite powder
The surface of the ferromagnetic hexagonal ferrite particles is a dispersion medium, polymer
It is also being processed with substances that suit the conditions. surface treatment
The material is an inorganic compound or an organic compound. Main compounds
As Si, Al, P, etc.
Typical examples are pulling agents and various titanium coupling agents.
The The amount is 0.1 to 10% with respect to the ferromagnetic powder. strength
The pH of the magnetic hexagonal ferrite powder is also important for dispersion.
Usually about 4 to 12, there is an optimum value depending on the dispersion medium and polymer.
However, it is about 6 to 11 because of the chemical stability and storage stability of the medium.
Selected. Water contained in ferromagnetic hexagonal ferrite powder
Minutes also affect dispersion. The optimum value depends on the dispersion medium and polymer.
However, usually 0.01 to 2.0% is selected. As a method for producing ferromagnetic hexagonal ferrite powder
There are the following methods, but the present invention does not choose a manufacturing method.
Yes. Barium oxide, iron oxide, metal oxides and iron
Boron oxide, etc. as a lath forming material
After mixing to become a composition, it is melted and quenched to form an amorphous material.
And then reheated, washed and ground to barium
Glass crystallization method to obtain ferrite crystal powder. Barium ferrite composition metal salt solution neutralized with alkali
Then, after removing the by-product, liquid phase heating was performed at 100 ° C. or higher.
After washing, drying and grinding, barium ferrite crystal powder
Obtain hydrothermal reaction method. Barium ferrite composition metal salt solution neutralized with alkali
After removing by-products and drying at 1100 ° C or lower
And co-precipitate to obtain barium ferrite crystal powder by grinding
Law. [Non-magnetic powder] The magnetic recording medium of the present invention comprises:
A magnetic layer may be provided directly on a nonmagnetic support.
Can also be made from a binder and nonmagnetic powder on a nonmagnetic support.
It is also possible to have a nonmagnetic layer. Used for non-magnetic layers
The nonmagnetic powder that can be produced may be an inorganic substance or an organic substance. Ma
Carbon black or the like can also be used. As an inorganic substance
For example, metal, metal oxide, metal carbonate, metal sulfuric acid
Salt, metal nitride, metal carbide, metal sulfide, etc.
The Specifically, titanium oxide such as titanium dioxide,
Lilium, tin oxide, tungsten oxide, ZnO, ZrO
₂, SiO₂, Cr₂O_Three, Α-a with an alpha conversion rate of 90-100%
Lumina, β-alumina, γ-alumina, α-iron oxide,
-Tight, corundum, silicon nitride, titanium carbide,
Magnesium oxide, boron nitride, molybdenum disulfide, acid
Copper chloride, MgCO_Three, CaCO_Three, BaCO_Three, SrCO_Three,
BaSO_Four, Silicon carbide, titanium carbide, etc. alone or in combination
It can be used in combinations of more than one kind. preferable
Those are α-iron oxide and titanium oxide. Non-magnetic powder
The shape may be any of a needle shape, a spherical shape, a polyhedron shape, and a plate shape.
The crystallite size of the non-magnetic powder is 4 nm to 1 μm
Is preferable, and 40 nm to 100 nm is more preferable.
Good. If it is 4 nm or more, the dispersibility is good.
If m or less, it is possible to obtain a coating film with good surface smoothness.
it can. These nonmagnetic powders have an average particle size of 5 nm to 2 μm.
Is preferable, but if necessary, non-magnetic powder with different average particle size
Wide particle size distribution even with powdered or single non-magnetic powder
Thus, the same effect can be achieved. Especially preferred
Specifically, it is 100 to 200 nm. 5nm or more
If the dispersibility is good, the surface smoothness is 2 μm or less.
A highly resistant coating film can be obtained. Specific surface of non-magnetic powder
The product is 1-100m²/ G, preferably 5 to 70
m²/ G, more preferably 10 to 65 m.²/ G
It is appropriate. 1m²/ G or more, surface flatness
A film with high lubricity can be obtained, 100 m²/ G or less
If so, the desired amount of binder can be dispersed well.
Dispersibility is good. Dibutyl phthalate (D
Oil absorption using BP) is 5-100 ml / 100 g, good
Preferably 10-80ml / 100g, more preferably 2
It is suitable that it is 0-60ml / 100g. specific gravity
Is suitably 1-12, preferably 3-6
The Tap density is 0.05-2g / ml, preferably
It is suitable that it is 0.2-1.5 g / ml. T
If the density is 0.05 g / ml or more, particles are scattered.
If it is less than 2g / ml, sticking to the device will occur.
Both are easy to operate. Non-magnetic powder
The pH is preferably 2-11, and is between 6-9
It is particularly preferable. If the pH is 2 or higher,
Appropriate if the coefficient of friction under high humidity is small and 11 or less
The amount of fatty acid is liberated and the coefficient of friction can be reduced
The The moisture content of the non-magnetic powder is 0.1 to 5% by mass, preferably
Is 0.2 to 3% by mass, more preferably 0.3 to 1.5%
It is suitable that the amount is%. If it is 0.1% by mass or more
If the dispersibility is good and 5% by mass or less, the dispersion
Later paint viscosity is stabilized. The ignition loss is 20% by mass or less.
It is preferable that there is a small loss on ignition.
Yes. If the non-magnetic powder is an inorganic powder, the mode
The hardness is preferably 4 or more and 10 or less. Mohs Hard
If the degree is less than 4, there is a tendency that durability cannot be secured.
The The amount of stearic acid adsorbed by non-magnetic powder is 1-20μmo
l / m²And more preferably 2 to 15 μmol / m²Is
Is appropriate. Wet nonmagnetic powder in water at 25 ° C
Heat is 20-60μJ / cm ²(200 erg / cm²~ 6
00 erg / cm²) Is preferable. Ma
Solvents in this wet heat range can be used.
The The amount of water molecules on the surface at 100 to 400 ° C. is 1 to 10
It is appropriate that the number is 100/100 pieces. Isoelectric point in water
The pH of is preferably between 3 and 9. These non
On the surface of the magnetic powder, Al₂O_Three, SiO₂TiO₂, Z
rO₂, SnO₂, Sb₂O_ThreeSurface treatment with ZnO
Is preferred. Particularly preferred for dispersibility is Al.₂O_Three,
SiO ₂TiO₂, ZrO₂And more preferred
Al₂O_Three, SiO₂, ZrO ₂It is. These are unions
May be used alone or may be used alone. Ma
Alternatively, a co-precipitated surface treatment layer may be used depending on the purpose.
First, after treating with alumina, the surface layer is treated with silica.
It is also possible to take a method of processing, or vice versa.
The surface treatment layer may be a porous layer depending on the purpose.
Although not homogeneous, it is generally preferred to be homogeneous and dense. In the present invention, the nonmagnetic layer used in the nonmagnetic layer is used.
Specific examples of magnetic powders include Showa Denko Nano Thailand
G, HIT-100, ZA-G1, manufactured by Sumitomo Chemical, Toda Industries
DPN-250, DPN-250BX, DPN-2
45, DPN-270BX, DPB-550BX, DP
N-550RX Titanium oxide TTO-51 made by Ishihara Sangyo
B, TTO-55A, TTO-55B, TTO-55
C, TTO-55S, TTO-55D, SN-100,
MJ-7, α-iron oxide E270, E271, E300,
STT-4D, STT-30D, STT- manufactured by Titanium Industry
30, STT-65C, Teica MT-100S, MT
-100T, MT-150W, MT-500B, MT-
600B, MT-100F, MT-500HD, Sakai Chemical
FINEX-25, BF-1, BF-10, BF-2
0, ST-M, Dowa Mining DEFIC-Y, DEFIC
-R, AS2BM manufactured by Nippon Aerosil, TiO2P25,
Ube Industries 100A, 500A, Titanium Industry Y-LO
P and the thing which baked it are mentioned. Especially preferred
Nonmagnetic powders are titanium dioxide and α-iron oxide. In the nonmagnetic layer, carbon is used together with nonmagnetic powder.
Mixing black to lower surface electrical resistance (Rs)
Can reduce the light transmittance and desired
The micro Vickers hardness can be obtained. Non-magnetic
The micro Vickers hardness of the layer is usually 25-60 kg /
mm²Preferably for adjusting per head
30-50kg / mm²Thin film hardness tester (Japan
Using electrical HMA-400), ridge angle 80 degrees, tip
A diamond triangular pyramid needle with a radius of 0.1 μm is used at the tip of the indenter.
Can be measured. Light transmittance is generally 9
Absorption of infrared rays of about 00 nm is 3% or less, for example, VHS
The standard for magnetic tapes is 0.8% or less.
ing. For this purpose, a rubber furnace and a rubber therma
, Black for color, acetylene black, etc.
be able to. In the present invention, the cathode used for the nonmagnetic layer is used.
-The specific surface area of Bon Black is 100-500m²/ G,
Preferably 150-400m²/ G, DBP oil absorption is 2
0-400ml / 100g, preferably 30-200m
It is appropriate to be 1/100 g. Carbon black
The particle size of the particles is 5 to 80 nm, preferably 10 to 50 n
m, more preferably 10 to 40 nm
It is. Carbon black has a pH of 2-10 and a water content of
0.1 to 10%, tap density is 0.1 to 1 g / ml
It is preferable. The carbon black used in the present invention.
As a concrete example, BLACKP manufactured by Cabot Corporation
EARLS 2000, 1300, 1000, 900,
800, 880, 700, VULCAN XC-72,
# 3050B, 3150B, 3250 manufactured by Mitsubishi Chemical Industries
B, # 3750B, # 3950B, # 950, # 650
B, # 970B, # 850B, MA-600, Colombi
CONDUCTEX SC, RAVEN made by Acarbon
  8800, 8000, 7000, 5750, 525
0, 3500, 2100, 2000, 1800, 150
0, 1255, 1250, Ketchumbra made by Akzo
EC and the like. Carbon black dispersant
Use with surface treatment or grafted with resin
Even if you use a part of the surface graphitized
It doesn't matter. Also add carbon black to the paint
It may be dispersed in advance with a binder. these
Of carbon black is 50 mass with respect to the inorganic powder.
% Does not exceed 40% of the total mass of the nonmagnetic layer.
Can be used in a range. These carbon blacks are
Or they can be used in combination. Non-magnetic of the present invention
Carbon black that can be used in the layer is, for example, “carbon black”
Refer to “Rack Handbook” (Carbon Black Association)
be able to. For the nonmagnetic layer, an organic powder is used for the purpose.
Can also be added. For example, acrylic styrene
Resin powder, benzoguanamine resin powder, melamine tree
Examples include fat powder and phthalocyanine pigments.
Tin resin powder, polyester resin powder, polyamide
Resin powder, polyimide resin powder, polyfluoroethylene
Resin can also be used. [Other Additives] In the magnetic recording medium of the present invention.
In addition, the magnetic layer or the non-magnetic layer has a dispersion effect and a lubrication effect.
Addition to give fruit, antistatic effect, plastic effect, etc.
An agent may be contained. These additives include molybdenum disulfide
Buden, tungsten disulfide, graphite, boron nitride
Silicon, fluorinated graphite, silicone oil, silicon with polar group
Corn, fatty acid-modified silicone, fluorine-containing silicon
, Fluorine-containing alcohol, fluorine-containing ester, poly
Olefin, polyglycol, polyphenyl ether,
Phenylphosphonic acid, benzylphosphonic acid group, phenethyl
Phosphonic acid, α-methylbenzylphosphonic acid, 1-methyl
Tyl-1-phenethylphosphonic acid, diphenylmethylphospho
Sulfonic acid, biphenylphosphonic acid, benzylphenylphospho
Sphonic acid, α-cumylphosphonic acid, toluylphosphone
Acid, xylylphosphonic acid, ethylphenylphosphonic acid,
Cumenylphosphonic acid, propylphenylphosphonic acid,
Tylphenylphosphonic acid, heptylphenylphosphone
Acid, octylphenylphosphonic acid, nonylphenylphosphine
Aromatic ring-containing organic phosphonic acids such as phonic acid and their al
Potassium metal salt, octylphosphonic acid, 2-ethylhexyl
Phosphonic acid, isooctylphosphonic acid, (iso) nonyl
Phosphonic acid, (iso) decylphosphonic acid, (iso) un
Decylphosphonic acid, (iso) dodecylphosphonic acid, (I
So) hexadecylphosphonic acid, (iso) octadecylphospho
Alkyl such as sulfonic acid and (iso) eicosylphosphonic acid
Phosphonic acid and its alkali metal salts, phenyl phosphate,
Benzyl phosphate, phenethyl phosphate, α-methylbenze phosphate
, 1-methyl-1-phenethyl phosphate, diphenyl phosphate
Methyl, biphenyl phosphate, benzylphenyl phosphate, phosphoric acid
α-cumyl, toluyl phosphate, xylyl phosphate, ethyl phosphate
Phenyl, cumenyl phosphate, propylphenyl phosphate, phosphoric acid
Butylphenyl, heptylphenyl phosphate, octyl phosphate
Aromatic phosphate esters such as phenyl and nonylphenyl phosphate
And alkali metal salts thereof, octyl phosphate, 2-ethyl phosphate
Tilhexyl, isooctyl phosphate, (iso) nonyl phosphate
, Phosphoric acid (iso) decyl, phosphoric acid (iso) undecyl, phosphorus
Acid (iso) dodecyl, phosphoric acid (iso) hexadecyl, phosphoric acid
Phosphorus such as (iso) octadecyl, phosphate (iso) eicosyl
Acid alkyl esters and alkali metal salts thereof, alkyl
Sulfonic acid esters and alkali metal salts thereof
Alkyl sulfate containing silicon and its alkali metal
Salt, lauric acid, myristic acid, palmitic acid, steer
Phosphoric acid, behenic acid, butyl stearate, oleic acid,
Such as linoleic acid, linolenic acid, elaidic acid, erucic acid, etc.
It is branched even if it contains an unsaturated bond with 10 to 24 carbon atoms.
Also good monobasic fatty acids and their metal salts, or
Butyl stearate, octyl stearate, steari
Amyl acid, Isooctyl stearate, Myristic acid
Octyl, butyl laurate, butoxye stearate
Chill, anhydrosorbitan monostearate, anhy
Drosorbitan distearate, anhydrosorbitan
C10-24 unsaturated bonds such as tristearate
Monobasic fatty acids that may be included or branched and 2 carbon atoms
1 to 22 which may contain or be unsaturated bonds
Hexavalent alcohol, containing C12-22 unsaturated bonds
But it may be branched alkoxy alcohol or alcohol
Monoalkyl ether of alkylene oxide polymer.
Mono-fatty acid ester, di-fatty acid ester consisting of only one
Steal or polyhydric fatty acid ester, C2-22 fat
Uses fatty acid amides, aliphatic amines having 8 to 22 carbon atoms, etc.
it can. In addition to the above hydrocarbon groups, nitro groups and
F, Cl, Br, CF_Three, CCl_Three, CBr_ThreeIncluding halo
Alkyl substituted with groups other than hydrocarbon groups such as gen hydrocarbons
It may have a group, aryl group or aralkyl group. Ma
Alkylene oxide, glycerin, glycid
Alkyl phenolic ethylene oxide adduct
Nonionic surfactant such as cyclic amine, ester amine
Quaternary ammonium salts, hydantoin derivatives, compound
Catheters such as rings, phosphoniums or sulfoniums
Surfactant, carboxylic acid, sulfonic acid, sulfuric acid ester
Anionic surfactants and amino acids containing acidic groups such as
, Aminosulfonic acids, amino alcohol sulfuric acid or
Are amphoteric interfaces such as phosphate esters and alkylbetaine types
An activator or the like can also be used. About these surfactants
Is detailed in "Surfactant Handbook" (published by Sangyo Tosho Co., Ltd.)
It is described in detail. These lubricants, antistatic agents, etc.
Not necessarily pure, but isomers, unreacted substances,
Impurities such as side reaction products, decomposition products, and oxides may be included.
Absent. These impurities are preferably 30% by mass or less.
More preferably, it is suitable that it is 10 mass% or less.
The Specific examples of these are those manufactured by NOF Corporation:
NAA-102, castor oil hydrogenated fatty acid, NAA-42,
Cation SA, Naimine L-201, Nonion E-2
08, Anon BF, Anon LG, Takemoto Yushi Co., Ltd .: FAL
-205, FAL-123, manufactured by Shin Nippon Rika Co., Ltd.
Lub OL, Shin-Etsu Chemical: TA-3, Lion Armor
Company: Armide P, Lion: Duomin TD
O, Nisshin Oil Industries: BA-41G, Sanyo Kasei: Pro
Juan 2012E, New Pole PE61, Ionette
MS-400 and the like. These dispersions used in the present invention
Agents, lubricants, and surfactants are nonmagnetic layers and magnetic layers.
You can use different types and quantities as needed. For example,
Of course, it is not limited to the example shown here.
Powders have the property of adsorbing or binding with polar groups.
In the magnetic layer, the surface of the ferromagnetic powder is mainly nonmagnetic.
In the layer, the polar group absorbs mainly on the surface of the non-magnetic powder.
Organophosphorus compounds that have adsorbed or bonded and once adsorbed
Or presumably difficult to desorb from the surface of metal compounds, etc.
The Therefore, the surface of the ferromagnetic powder of the present invention or the non-magnetic powder table
The surface is covered with an alkyl group, aromatic group, etc.
As a result, the binder tree of ferromagnetic powder or non-magnetic powder
Affinity to fat components is improved, and there is a ferromagnetic powder.
Alternatively, the dispersion stability of the nonmagnetic powder is also improved. Also lubrication
As an agent, it exists in a free state, so non-magnetic layer, magnetic layer
Controls bleeding to the surface using fatty acids with different melting points
To the surface using esters with different boiling points and polarities
Controls bleeding and adjusts the amount of surfactant to apply
The nonmagnetic layer adds lubricant to improve the stability of the fabric.
Increasing the lubricating effect can be considered. Also
All or part of the additives used in the present invention are
Any process during the production of coating solutions for magnetic or nonmagnetic layers
May be added. For example, before the kneading process
When mixing, kneading with ferromagnetic powder, binder and solvent
If added in the process, if added in the dispersion step, after dispersion
In some cases, it is added just before coating. [Nonmagnetic support] Prepared with the above materials.
Apply a coating solution on a non-magnetic support to form a non-magnetic layer or a magnetic layer.
Form a layer. Non-magnetic that can be used in the present invention
As a flexible support, polyethylene naphtha that has been biaxially stretched is used.
Talate, polyethylene terephthalate, polyamide,
Polyimide, polyamideimide, aromatic polyamide, poly
Well-known things, such as rivens oxidazole, are mentioned.
Preferably polyethylene naphthalate, aromatic polyamid
It is. These nonmagnetic supports are pre-corona-released.
Even if electricity, plasma treatment, easy adhesion treatment, heat treatment, etc.
good. Further, the non-magnetic support that can be used in the present invention.
The holder has a center line average surface roughness of 0.25 m as a cutoff value.
m is 0.1 to 20 nm, preferably 1 to 10 nm.
It is preferable to have excellent surface smoothness in the range of
Yes. These nonmagnetic supports also have a centerline average surface roughness.
Is not only small, but there is no coarse protrusion of 1μ or more
preferable. The arithmetic average roughness of the obtained support is (Ra)
Value [JIS B0660-1998, ISO 4287
-1997] was 0.1 μm or less.
This is preferable because the noise of the magnetic recording medium is reduced. Main departure
Preferred thickness of nonmagnetic support in bright magnetic recording media
Is 3 to 80 μm. [Backcoat layer, undercoat layer] In the present invention,
The surface of the nonmagnetic support that is not coated with the magnetic coating solution
Even if a backcoat layer (backing layer) is provided
Good. The backcoat layer is composed of a magnetic coating solution and a nonmagnetic support.
And non-magnetic coating liquid.
A particulate component such as an inhibitor and a binder are dispersed in an organic solvent.
It is a layer provided by applying a backcoat layer forming coating solution.
is there. Various inorganic pigments and carbon black as particulate components
Nitrose can be used as a binder.
Rulose, phenoxy resin, vinyl chloride resin, polyurethane
Use resin such as let alone or a mixture of these.
be able to. In the present invention, the nonmagnetic support
For magnetic coating solution, non-magnetic coating solution, or backcoat layer formation
An adhesive layer may be provided on the coating surface of the coating liquid. Ma
In the magnetic recording medium of the present invention, an undercoat layer is provided.
May be. Support and magnetic properties by providing an undercoat layer
The adhesive force with the layer or the nonmagnetic layer can be improved.
As an undercoat layer, a solvent-soluble polyester resin
Can be used. Undercoat layer is 0.5μm thick
It is appropriate to use: [Production Method] Production of Magnetic Recording Medium of the Present Invention
For example, the method can be achieved by applying magnetic properties to the surface of a nonmagnetic support under running.
The coating liquid is applied so as to have a predetermined film thickness. Here
Multiple magnetic layer coating solutions may be applied sequentially or simultaneously
The non-magnetic layer coating solution and the magnetic layer coating solution sequentially or simultaneously.
Multiple layers may be applied. Magnetic coating solution or nonmagnetic layer coating
As an application machine to apply the liquid, air doctor coat,
Blade coat, rod coat, extrusion coat, air na
If coat, squeeze coat, impregnation coat, reverse low
Coat, transfer roll coat, graviaco
Coat, kiss coat, cast coat, spray coat,
A spin coat etc. can be used. For example,
"Latest coating technology" issued by General Technology Center Co., Ltd.
"Jun" (May 31, 1983) can be referred to. The present invention
When applying to a magnetic recording medium of
The following can be proposed as an example. (1) Magnetic layer coating solution
Gravure, rolls and branes commonly applied in coatings
First, non-magnetic
The non-magnetic layer is applied in a dry state.
No. 1-46186, JP-A-60-238179
Disclosed in Japanese Patent Laid-Open No. 2-265672.
By using such a support pressure type extrusion coating device
Apply the magnetic layer. (2) JP-A-63-88080
No. 1, JP-A-2-17971, JP-A-2-26
A coating liquid passing thread as disclosed in Japanese Patent No. 5672
The upper and lower layers are almost separated by a single coating head having two
Apply at the same time. (3) Japanese Patent Laid-Open No. 2-174965
With backup role as disclosed in
The upper and lower layers are applied almost simultaneously using a trusion coating device.
Cloth. In the magnetic recording medium of the present invention, the magnetic layer
The thickness is the saturation magnetization of the head used, the head gap length,
It is optimized by the bandwidth of the recording signal,
Is 0.01-0.10 μm, preferably 0.02-0.
08 μm, more preferably 0.03 to 0.08 μm.
m is suitable. Magnetic layer with different magnetic properties
It may be separated into two or more layers having a known multilayer magnetic property.
Layer related configurations are applicable. This ultra-thin magnetic layer
In order to apply regularly, it contains inorganic powder on the support.
A magnetic layer on top of the nonmagnetic layer.
It is desirable to apply on wet. Magnetic layer coating
In the case of magnetic tape, the liquid coating layer is a magnetic layer coating liquid coating layer.
Cobalt magnets and solenoids are added to the ferromagnetic powder contained inside.
Using magnetic field orientation treatment in the longitudinal direction. Disc place
Fully isotropic orientation even without orientation without using an orientation device
May be obtained, but the cobalt magnets are alternated diagonally.
Such as placing an AC magnetic field with a solenoid
It is preferable to use a known random orientation device. Isotropic
In the case of a ferromagnetic metal fine powder, the normal orientation is generally in-plane 2
Dimensional random is preferred, but 3D with vertical component
It can also be random. For hexagonal ferrite
Is generally in-plane and vertical three-dimensional random
Easy, but can be in-plane 2D random
The Also, using a known method such as a magnet with a different polarity, vertical alignment
To provide isotropic magnetic properties in the circumferential direction.
You can also. Especially when performing high density recording, vertical alignment is preferred.
Good. Also, it may be circumferentially oriented using spin coating.
Yes. By controlling the temperature, air volume, and application speed of the drying air,
It is preferable to be able to control the drying position of the membrane.
The cloth speed is 20m / min to 1000m / min, and the drying air temperature is
60 ° C or higher is preferred, and moderate before entering the magnet zone
Can also be pre-dried. After drying, the coating layer
It is appropriate to subject the surface to a surface smoothing treatment. Surface smoothing
For example, a super calendar roll is used for processing.
Is done. By performing a surface smoothing treatment,
Of vacancies caused by removal of the agent disappeared and ferromagnetism in the magnetic layer
Magnetic powder with high electromagnetic conversion characteristics due to improved powder filling rate
A recording medium can be obtained. With calendaring role
Epoxy, polyimide, polyamide, polyamide
It is possible to use heat-resistant plastic rolls such as imide
it can. Moreover, it can also process with a metal roll. Main departure
Bright magnetic recording media have a surface centerline average roughness of
0.1 to 4 nm at an off value of 0.25 mm, preferably
Has extremely excellent surface smoothness in the range of 1 to 3 nm.
It is preferable to do. For example, as described above,
Magnetics formed by choosing specific ferromagnetic powder and binder
This is done by subjecting the layer to the above calendering. Mosquito
The render processing condition is the temperature of the calendar roll.
The range of 60-100 ° C, preferably the range of 70-100 ° C
, Particularly preferably in the range of 80-100 ° C., pressure
Is in the range of 100-500 kg / cm, preferably
200 to 450 kg / cm, particularly preferred
Is operated under conditions in the range of 300-400 kg / cm
Is preferably performed. Magnetic recording
The recording medium is cut into a desired size using a cutting machine.
Can be used. [0061] The following are specific examples of the present invention and comparisons.
For example, the present invention is not limited to this example.
There is no. In addition, the display of “part” in the embodiment is not particularly refused.
As long as it indicates “parts by mass”. [Synthesis Examples 1 and 2] Polar group-containing acrylonitrile-styrene resin Equipped with a stirrer, condenser, thermometer and nitrogen gas inlet
The obtained polymerization vessel was purged with nitrogen and heated to 60 ° C. and shown in Table 1.
A monomer component dissolved in 200 parts of cyclohexanone
Solution and 0.5 part of 2,2'-azobisisobutyronitrile.
The solution dissolved in 10 parts of cyclohexanone is simultaneously mixed with the above
It was dripped uniformly into the polymerization vessel over 2 hours. End of dripping
After completion, heat at 60 ° C for 4 hours to complete the polymerization.
Rilonitrile-styrene resin (AS-1, AS-2)
Obtained. [0062] [Synthesis Example 3] Polyurethane resin PU1 A container equipped with a reflux condenser and a stirrer and previously purged with nitrogen       100 parts of polyester polyol 1       (Neohexyl glycol / cyclohexane dimethanol / adhydic acid /       5-sodium sulfoisophthalic acid = 2/3/3 / 1mol ratio, Mn1500)       100 parts of 2,2-diethyl-1,3-propanediol       467 parts of cyclohexanone Was dissolved at 60 ° C. under a nitrogen stream. Then as a catalyst
Add dibutyltin dilaurate 60ppm and add 1
Dissolved for 5 minutes. Diphenylmethane diisocyanate
Add 206 parts and 481 parts cyclohexanone to add 9
Heat reaction at 0 ° C for 6 hours, polyurethane resin solution PU
1 was obtained. The resulting polyurethane resin PU1 is
It corresponds to letan B, and its weight average molecular weight is 75000,
Tg is 85 ° C., urethane group concentration is 4.1 meq / g, S
O _ThreeThe Na group concentration was 0.16 meq / g. [0063] [Synthesis Example 4] Polyurethane resin PU2 A container equipped with a reflux condenser and a stirrer and previously purged with nitrogen       100 parts of polyester polyol 2       (2,2-diethyl-1,3-fluorodiol / adic acid /       5-sodium sulfoisophthalic acid = 5/3/1 mol ratio, Mn1500)       100 parts of neopentyl glycol       467 parts of cyclohexanone Was dissolved at 60 ° C. under a nitrogen stream. Then as a catalyst
Add dibutyltin dilaurate 60ppm and add 1
Dissolved for 5 minutes. Diphenylmethane diisocyanate
G and 257 parts and cyclohexanone 600 parts 9
Heat reaction at 0 ° C for 6 hours, polyurethane resin solution PU
2 was obtained. The resulting polyurethane resin PU2 is
It corresponds to letan B, and its weight average molecular weight is 75000,
Tg is 85 ° C., urethane group concentration is 4.5 meq / g, S
O _ThreeThe Na group concentration was 0.15 meq / g. [0064] [Synthesis Example 5] Polyurethane resin PU3 A container equipped with a reflux condenser and a stirrer and previously purged with nitrogen       100 parts of polyether polyol       (Propylene oxide adduct of bisphenol A, Mn1000)       100 parts of cyclohexanedimethanol       5-sodium sulfoisophthalic acid diethylene glycol 15 parts       502 parts of cyclohexanone Was dissolved at 60 ° C. under a nitrogen stream. Then as a catalyst
Add dibutyltin dilaurate 60ppm and add 1
Dissolved for 5 minutes. Diphenylmethane diisocyanate
90 parts by adding 192 parts and 448 parts of cyclohexanone
Heat reaction at 6 ° C for 6 hours, polyurethane resin solution PU3
Got. Obtained polyurethane resin PU3, Polyureta
The weight average molecular weight is 75000, Tg.
Is 95 ° C., urethane group concentration is 3.7 meq / g, SO_Three
The concentration of Na group was 0.10 meq / g. [0065] [Synthesis Example 6] Polyurethane resin PU4   A container equipped with a reflux condenser and a stirrer and previously purged with nitrogen       100 parts dimer diol       100 parts of hydrogenated bisphenol A       5-sodium sulfoisophthalic acid diethylene glycol 15 parts       502 parts of cyclohexanone Was dissolved at 60 ° C. under a nitrogen stream. Then as a catalyst
Add dibutyltin dilaurate 60ppm and add 1
Dissolved for 5 minutes. Diphenylmethane diisocyanate
And 298 parts of cyclohexanone and 695 parts of cyclohexanone
Heat reaction at 0 ° C for 6 hours, polyurethane resin solution PU
4 was obtained. The resulting polyurethane resin PU4 is
It corresponds to letan C, and its weight average molecular weight is 62000,
Tg is 158 ° C., urethane group concentration is 3.4 meq / g,
SO_ThreeThe Na group concentration was 0.11 meq / g. [0066] [Comparative Synthesis Example 1] Polyurethane resin PU5   A container equipped with a reflux condenser and a stirrer and previously purged with nitrogen       25 parts of polyester polyol 1         (Neohexyl glycol / cyclohexanedimethanol / adhydic acid /       5-sodium sulfoisophthalic acid = 2/3/3 / 1mol ratio, Mn1500)         Polyester polyol 3 75 parts       (Neo-hexyl glycol / cyclohexanedimethanol / adic acid / isophthalic acid =       2/3/3 / 1mol ratio, Mn1500)       20 parts of neopentyl glycol       467 parts of cyclohexanone Was dissolved at 60 ° C. under a nitrogen stream. Then as a catalyst
Add dibutyltin dilaurate 60ppm and add 1
Dissolved for 5 minutes. Diphenylmethane diisocyanate
90 parts by adding 65 parts and 481 parts cyclohexanone
Heat reaction at 6 ° C for 6 hours, polyurethane resin solution PU5
Got. The resulting polyurethane resin PU5 has a weight average
Molecular weight 65000, Tg85 ° C, Urethane group concentration 2.8
meq / g, SO_ThreeNa group concentration 0.09 meq / g
It was. [0067] [Example 1]Preparation of upper layer magnetic coating solution       100 parts of ferromagnetic needle metal powder       Composition: Fe / Co / Al / Y = 62/25/5/8       Surface treatment agent: Al₂O_Three, Y₂O_Three        Hc: 167 kA / m (2100 Oe)       Crystallite size: 110Å       Long axis length: 60 nm,       Needle ratio: 6       BET specific surface area: 70 m²/ G       σs: 110 A · m²/ Kg (110 emu / g)       6 parts of polar group-containing acrylonitrile-styrene resin AS-1       30 parts of polyurethane resin solution PU1 (30% cyclohexanone solution)       α-Al₂O_Three(Particle size 0.15 μm) 2 parts       Carbon black (particle size 20nm) 2 parts       110 parts of cyclohexanone       100 parts of methyl ethyl ketone       100 parts of toluene       Butyl stearate 2 parts       1 part of stearic acid       Benzoic acid 3 parts [0068]Preparation of nonmagnetic coating solution for lower layer       85 parts of non-magnetic inorganic powder               α-iron oxide               Surface treatment agent: Al₂O_Three, SiO₂               Long axis diameter: 0.15 μm               Tap density: 0.8               Needle ratio: 7               BET specific surface area: 52 m²/ G               pH 8               DBP oil absorption: 33g / 100g       20 parts of carbon black                 DBP oil absorption: 120ml / 100g                 pH: 8                 BET specific surface area: 250 m²/ G                 Volatile content: 1.5%       6 parts acrylonitrile styrene resin AS-1       30 parts of polyurethane resin solution PU1 (30% cyclohexanone solution)       α-Al₂O_Three(Average particle size 0.2 μm) 1 part       140 parts of cyclohexanone       170 parts of methyl ethyl ketone       Butyl stearate 2 parts       1 part of stearic acid       Phenylphosphoric acid 3 parts The above magnetic coating solution for the upper layer and nonmagnetic for the lower layer
For each coating solution composition, open ingredients
Kneading for 60 minutes with a mixer, then 120 minutes with a sand mill
Distributed. The resulting dispersion is trifunctional low molecular weight polyiso
Cyanate compound (Nihon Polyurethane Coronate 3
041) is added, and after further stirring and mixing for 20 minutes,
Filtered using a filter having an average pore size of 1 μm,
A magnetic coating solution and a nonmagnetic coating solution were prepared. Thickness 3.8
After drying the above non-magnetic paint on the surface of μm aramid support
Apply to a thickness of 1.8 μm, and
Later, the thickness after drying the magnetic coating will be 0.08μm
A simultaneous multilayer coating was applied. Magnetic field orientation treatment with both layers undried
After drying the solvent, the speed is 10 on a 7-stage calendar.
0m / min, linear pressure 300kgf / cm, temperature 90 ° C
Performed under conditions. 0.3T (300 when both layers are undried
(0 gauss) magnet for magnetic field orientation, and after drying, gold
Speed is 1 with a 7-stage calendar consisting of only genus rolls
00m / min, linear pressure 300kg / cm, temperature 90 ° C
After surface smoothing treatment, heat hardening at 70 ° C. for 24 hours
To make a magnetic tape by slitting to 3.8mm width.
Made. Examples 2 to 5 and Comparative Example 1 Acryloni
Table 2 shows tril-styrene resin and polyurethane resin.
This was prepared in the same manner as in Example 1 except that Comparative Example 2 Acrylonitrile of Comparative Example 1
-Styrene resin with vinyl chloride resin MR110 (Nippon Zeon)
It was created in the same manner as in Comparative Example 1 except that it was changed to “made by Co., Ltd.”. [Example 6] The magnetic material of Example 1 is shown below.
It was created in the same manner as in Example 1 except that it was changed as described above.       100 parts of ferromagnetic plate-shaped hexagonal ferrite powder               Composition (molar ratio): Ba / Fe / Co / Zn = 1/9 / 0.2 / 1               Hc: 159 kA / m (200 Oe)               Plate diameter: 25 nm, plate ratio: 3               BET specific surface area: 80m²/ G               σs: 50 A · m²/ Kg (50 emu / g) [Comparative Example 3] Acrylonitrile of Example 6
-Styrene resin with vinyl chloride resin MR110 (Nippon Zeon)
(Made by Co., Ltd.) and changed the polyurethane resin to PU-5
Except that, it was created in the same manner as in Example 6. [Measurement method] Film mechanical strength: initial length of tape sample with tensile tester
The measurement was performed at 50 mm and a stretching speed of 50 mm / min. The
Wipe the sample film with gauze impregnated with THF
Tensile tests are performed under the same conditions using only the base film.
It was. SS of the tape sample (Stress-Stra
in) Tensile stress from curve and base SS curve
The SS curve of the coating film was determined on the assumption of additivity. Obtained
Yield elongation (%) and yield strength (MP
a) was determined. Tape edge (magnetic layer) cracks:
The magnetic layer surface of the loop edge is observed with a microscope to observe cracks.
What was observed was marked with X, and what was not observed was marked with ◯. Magnetic layer surface roughness Ra: Digital optical profile
By optical interferometry using a filter (manufactured by WYKO).
The center line average roughness is Ra under the condition of a top-off of 0.25 mm.
It was. Head dirt after running 500 passes: Sun with DDS drive
After running the pull tape repeatedly for a total length of 500 passes
The head dirt was observed. X, see what is dirty
Those that could not be evaluated were marked with ○. Add another 6 tape samples
The same evaluation was made after storage for 7 days in a 0 ° dry atmosphere.
It was. [0075] [Table 1][0076] [Table 2] [0077] [Table 3] Evaluation results Polar group-containing acrylonitrile-styrene resin and poly
A binder containing polyurethane corresponding to urethane A to C
Examples 1 to 6 used all have yield elongation and yield strength.
And the coating film mechanical strength was excellent. This is acrylo
Phase of nitrile-styrene resin and polyurethane A to C
This is thought to be due to the high solubility. Also, these implementation
In the example, the tape edge crack does not occur and the coating strength
Was also good. In addition, the binder resin contains polar groups and is dispersed
Excellent in surface smoothness of the magnetic layer.
It was. In addition, there is no head contamination after running 500 passes.
Durability was also good. Polar group-containing acrylonitrile
Contains styrene resin, but corresponds to polyurethane A to C
Including polyurethane (PU5) instead of polyurethane
In Comparative Example 1 using a binder, the coating film mechanical strength and magnetism
The layer surface smoothness was inferior to the examples. Tape tape
Cracks occur, and after 500 passes, the head
Dirt was observed. This is the polyurethane PU used
5 and low compatibility with acrylonitrile-styrene resin
This is thought to be due to Acrylonitrile
PVC resin MR110 instead of ru-styrene resin
Polyureta used and corresponding to polyurethane A to C
Ratio using polyurethane PU5 instead of using
In Comparative Examples 2 and 3, the coating film mechanical strength and the magnetic layer surface roughness
Similarly, Examples 1 to 5 using ferromagnetic metal powder,
From Example 6 using ferromagnetic hexagonal ferrite powder
It was inferior. In Comparative Examples 2 and 3, 500 pass running
After storage after line, head fouling was observed. this is,
Because PVC resin was used, hydrochloric acid gas was generated.
It is thought that it depends. [0079] The present invention provides an acryloni containing a polar group.
Polyure having a specific structure with tolyl-styrene resin
Using a binder containing tantalum in the magnetic layer and / or nonmagnetic layer
As a result, the dispersibility of ferromagnetic powder and non-magnetic powder is high.
Magnetic properties with excellent electromagnetic conversion characteristics, mechanical strength and running durability
An air recording medium can be provided. In addition, according to the present invention,
Therefore, it is possible to provide a magnetic recording medium with excellent storability.
The

Continued front page    (72) Inventor Yuichiro Murayama             2-1-12 Ogimachi, Odawara-shi, Kanagawa Prefecture             Shishi Photo Film Co., Ltd. Odawara Factory F-term (reference) 5D006 BA11 BA15 FA00 FA02

Claims (1)

What is claimed is: 1. A magnetic layer 1 comprising a ferromagnetic powder and a binder on a support, or a nonmagnetic layer comprising a nonmagnetic powder and a binder, and a ferromagnetic powder and a binder. A magnetic recording medium having a magnetic layer 2 in this order, wherein at least one of the binder contained in the magnetic layer 1 and the binder contained in the nonmagnetic layer and the magnetic layer 2 is-(O) _{-SO 3 M, - (O)} PO (OM) 2, -COO
M, —NR ₁ R ₂ , —NR ₁ R ₂ R ₃ ⁺ (M represents a hydrogen atom, an alkali metal or an ammonium salt, and R ₁ , R ₂ , R ₃ each represents a hydrogen atom or an alkyl group) Obtained from an acrylonitrile-styrene resin having a polar group, a polyol having a molecular weight of 500 to 5000 having a cyclic structure and an alkylene oxide chain, a polyol having a molecular weight of 100 to 500 having a cyclic structure as a chain extender, and an organic diisocyanate compound. (B) a polyurethane having a polar group obtained from a polyester polyol, a chain extender and an organic diisocyanate compound, wherein the diol component and / or the chain extender in the polyester polyol has 2 or more carbon atoms A polymer containing a branched aliphatic diol having an alkyl group as a side chain Urethane, and (C) a magnetic recording medium which comprises at least one polyurethane selected from polyurethane having a cyclic structure and a long alkyl chain polar group derived from a polyol compound and an organic diisocyanate compound having a.