JP2003257012A - Magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic recording medium having excellent coating film smoothness, electromagnetic transducing characteristics and running durability. <P>SOLUTION: The magnetic recording medium has an undercoat layer and at least one magnetic layer containing ferromagnetic powder and a binder in this order on a non-magnetic substrate. The undercoat layer comprises a polyester copolymer containing dibasic acid components containing 15 to 40 mol percent of metal sulfonate groups based on the whole dibasic acid components and/or glycol components containing 15 to 40 mol percent of metal sulfonate groups based on the whole glycol components. <P>COPYRIGHT: (C)2003,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to an excellent electromagnetic conversion characteristic.
The present invention relates to a magnetic recording medium having durability and durability. [0002] [0002] Audio, video, and computers
Tape-like magnetic recording media and floppy disks (registered traders)
Gamma acid as a disk-shaped magnetic recording medium such as a disk
Iron fluoride, Co-containing iron oxide, chromium oxide, ferromagnetic metal fine powder
A magnetic layer in which ferromagnetic fine powder such as
A magnetic recording medium provided on a magnetic support is used.
One non-magnetic support used for magnetic recording media is
Generally polyethylene terephthalate, polyethylene naphthalate
Rate is used. These supports are stretched
Highly crystallized for high mechanical strength and solvent resistance
Is excellent. Coating in which ferromagnetic fine powder is dispersed in a binder
The magnetic layer obtained by applying the liquid to a non-magnetic support is a ferromagnetic layer.
Undercoating due to high powder filling, small elongation at break and brittleness
A magnetic layer formed without a layer can be mechanically applied.
Can be easily broken and peeled off from non-magnetic support
There is. Therefore, an undercoat layer is provided on the nonmagnetic support,
The magnetic layer is strongly bonded onto the nonmagnetic support.
(Japanese Patent No. 2809287, Japanese Patent Laid-Open No. 1-24)
No. 5421). However, the previously used undercoat layer is shaped.
Since the resin component to be formed has high solvent solubility,
By applying a magnetic layer to the undercoat layer, the undercoat layer swells and
There was a problem that surface smoothness was inferior. Furthermore, magnetic layer coating
The resin component that forms the undercoat layer is added to the solvent used in the liquid.
Because it melts, the resin component of the undercoat layer becomes magnetic after long-term storage.
May precipitate on the surface of the conductive layer and form fine crystals.
It was. This fine precipitate can cause dropout failures.
Magnetic recording for high-density recording, especially with a short recording wavelength
In the media, the impact is significant and becomes a serious problem.
It was. [0005] SUMMARY OF THE INVENTION Accordingly, the object of the present invention is as follows.
Has excellent coating smoothness and electromagnetic conversion characteristics, and running
It is an object of the present invention to provide a magnetic recording medium having excellent line durability. [0006] The object of the present invention is to
Undercoat layer and ferromagnetic powder and binder on magnetic support
Magnetic recording having at least one magnetic layer in this order
A medium, wherein the undercoat layer is based on the total dibasic acid component.
Containing 15 to 40 mol% sulfonic acid metal base
15 to 15 base acid components and / or total glycol components
Glycol containing 40 mol% sulfonic acid metal base
Including a polyester copolymer containing components
This is achieved by a magnetic recording medium. The above police
The glass transition temperature of the ter copolymer is 80 to 200 ° C.
It is preferable. [0007] BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a magnetic recording medium of the present invention will be described.
Will be described in more detail. [Undercoat layer] The magnetic recording medium of the present invention comprises an
15-40 mol% metal sulfonate based on the basic acid component
Dibasic acid component containing a base (hereinafter referred to as “SO_ThreeM containing D
Basic acid component) and / or total glycol component
Containing 15 to 40 mol% of a sulfonic acid metal base
Glycol component (hereinafter referred to as “SO_ThreeM-containing glycol
Including polyester copolymer containing
It is characterized by that. The polyester copolymer is
Highly hydrophilic because it contains a high concentration of phosphonate metal base
In general, ME used as a solvent in the magnetic layer coating solution
K, cyclohexanone, butyl acetate, THF, toluene
It has the characteristic that it hardly dissolves in This will allow you to
When the magnetic layer coating solution is applied onto the magnetic layer, the magnetic layer coating solution
Smoothness of the surface of the magnetic layer due to swelling of the undercoat layer with the solvent contained
Can be suppressed. Magnetic layer
After the polyester copolymer is dissolved in the coating solution and stored for a long time
On the surface of the magnetic layer, causing dropout failure.
It never happens. In addition, it is commonly used as a support.
Reethylene terephthalate, polyethylene naphthalate
High adhesion to polyester film
Excellent running durability can be obtained. SO_ThreeM containing D
The content of basic acid or glycol component is all dibasic acid component
Or less than 15 mol% based on the total glycol component
And by applying a magnetic layer on the undercoat layer
The layer swells and the smoothness of the magnetic layer located in the upper layer decreases.
The Furthermore, the polyester copolymer component dissolves into the magnetic layer.
And deposited on the surface of the magnetic layer after long-term storage.
It may cause a failure. On the other hand, the content is 40 mol%
If it exceeds the maximum, the coating film will absorb moisture easily.
It is inferior in preservability. In the present invention, the poly contained in the undercoat layer
The ester copolymer is 15 to 4 with respect to the total dibasic acid component.
0 mol% SO_ThreeWhether it contains an M-containing dibasic acid component
Or 15 to 40 mol% SO based on the total glycol component
_ThreeAn M-containing glycol component can also be contained. is there
Or the polyester copolymer contained in the undercoat layer is S
O_ThreeM-containing dibasic acid component and SO_ThreeM-containing glycol component
Any of these can also be contained in the said range. However
And SO_ThreeM-containing dibasic acid component and SO_ThreeM-containing glycol
When used in combination with components, the sulfur in the polyester copolymer
The content of phosphonate metal base is 350-1200 eq / t
It is preferable. Content of sulfonic acid metal base
Is within the above range, the undercoat layer is coated with the magnetic layer coating solution.
Preferable without swelling or preservability due to moisture absorption
Good. In the present invention, the polyester copolymer
Examples of the dibasic acid component include terephthalic acid,
Taric acid, orthophthalic acid, 1,5-naphthalene dicarboxylic
Acid, 2,6 naphthalene dicarboxylic acid, 4,4 'dipheny
Rudicarboxylic acid, 2,2'diphenyldicarboxylic acid,
Aromatic dimers such as 4,4'diphenyl ether dicarboxylic acid
Carboxylic acids and their dimethyl esters; succinic acid,
Adipic acid, azelaic acid, sebacic acid, dodecandica
Aliphatic dicarboxylic acids such as rubonic acid and their dimethyl
Ester; 1,4 cyclohexanedicarboxylic acid, 1,3
Cyclohexyl dicarboxylic acid, 1,2 cyclohexane di
Carboxylic acid, 4methyl 1,2 cyclohexane dicarboxylic acid
Alicyclic dicarboxylic acids such as acids and dimer acids
A methyl ester or the like can be used. Especially preferred
New ones are terephthalic acid, orthophthalic acid, 2,6
Phthalenedicarboxylic acids and their dimethyl esters
Can be mentioned. In the present invention, the polyester copolymer
Examples of the glycol component include ethylene glycol
Diethylene glycol, propylene glycol,
1,3 propanediol, 1,4 butanediol, 1,
5-pentanediol, 1,6-hexanediol, 1,9
Nonanediol, neopentyl glycol, triethyl
Glycol, tetraethylene glycol, dipropylene
Glycol 2,2,4 trimethyl 1,3-pentane
All, 2 ethyl 2-butyl 1, 3-propanediol,
Chlohexanediol, cyclohexanedimethanol, di
Methylol tricyclodecane, bisphenol A, hydrogen
Bisphenol A, ethylene oxide of bisphenol A
Side, or propylene oxide adduct, hydrogenated hydrogen
Sphenol A ethylene oxide or propylene
An oxide adduct or the like can be used. Above all
Preferred are ethylene glycol and triethylene glycol
Of recall, diethylene glycol, bisphenol A
An ethylene oxide adduct can be mentioned. A dibasic acid containing a metal sulfonate group;
For example, 5 sodium sulfoisophthalic acid,
Thorium sulfoterephthalic acid, 5-potassium sulfoisophthalic acid
For example, taric acid can be used.
It is preferable to use foisophthalic acid. Gold sulfonate
As a glycol component containing a genus base,
1,4-butanediol, 2,5-dimethyltrisodium
Sulfo 2,5 hexanediol etc. can be used,
Especially using disodium 1,4 butanediol
Is preferred. In the present invention, the SO_ThreeM-containing dibasic acid compound
15-40 mol% and / or the total dibasic acid component
Is the above SO_ThreeM-containing glycol component
15 to 40 mol% based on the amount of dibasic acid component and
By copolymerizing the recall component with a conventional method,
A reester copolymer is obtained. Polyester copolymer fraction
The molecular weight is preferably 20,000 to 200,000 in terms of weight average molecular weight.
More preferably, it should be 40,000 to 100,000
By appropriately setting the polymerization conditions, the above range
Polyester resin having a molecular weight of
The If the weight average molecular weight is 20,000 or more, the coating strength is high.
In addition, the adhesion to the support is good, and if it is 200,000 or less
For example, it is highly soluble in solvents and water, and the undercoat layer coating solution can be applied.
Can be easily performed. In the present invention, the above polyester copolymer
The glass transition temperature of the body is preferably 80 to 200 ° C.
It is more preferable that the temperature is 80 to 130 ° C.
The polymerization conditions such as the combination of monomers used
Is set appropriately to achieve the desired glass transition temperature.
A polyester copolymer can be obtained. Glass
If the transition temperature is 80 ° C or higher, it is applied to the roll in the coating process.
If there is no sticking failure and it is 200 ° C or less, it is flexible.
A coating film is obtained and the contact between the drive head and the tape is good.
Deterioration of electromagnetic conversion characteristics due to spacing loss
Is preferable because it does not occur. In the present invention, the thickness of the undercoat layer is 0.
It is preferably 1 to 1.5 μm, more preferably
0.5 to 1.0 μm. The thickness of the undercoat layer is 0.1μ
If m or more, sufficient coating smoothness can be obtained,
If the thickness is 1.5 μm or less, the coating film dries quickly, causing adhesion failure
This is preferable because it does not occur. [Non-magnetic support] For the magnetic recording medium of the present invention
As a nonmagnetic support that can be used, biaxial stretching is performed.
Polyethylene terephthalate, polyethylene naphthalate
Rate, polyamide, polyamideimide, aromatic poly
Known materials such as mid can be used. Above all, polyethylene
Terephthalate, polyethylene naphthalate, polya
It is preferred to use a mid. These supports are
Corona discharge, plasma treatment, easy adhesion treatment, heat treatment
You may do reason. It can also be used in the present invention.
For non-magnetic supports, the center line average roughness is the cutoff value.
Excellent surface of 3-10 nm at 0.25 mm
It is preferable to have smoothness. Also these non-magnetic
The support has a small center line average surface roughness of 1 μm.
It is preferable that there are no such coarse protrusions. On the non-magnetic support, the polyester
Apply an undercoat layer coating solution containing a copolymer to form an undercoat layer
And then a non-magnetic underlayer or a magnetic underlayer on the undercoat layer
(Hereinafter also referred to as “undercoat layer”)
Forming a layer or forming a magnetic layer directly on the subbing layer.
To produce a magnetic recording medium. Non-magnetic underlayer, magnetic underlayer, or
In the magnetic layer, nonmagnetic powder or ferromagnetic powder is dispersed in a binder.
Formed by applying a dispersed composition. As the binder, polyurethane resin, polyester
Steal resin, polyamide resin, vinyl chloride resin,
Styrene, acrylonitrile, methyl methacrylate
Acrylic resin copolymerized with nitrocellulose, etc.
Cellulosic resin, epoxy resin, phenoxy resin,
Polyvinyl acetal, polyvinyl butyral, etc.
Single or multiple materials such as Livinyl Alkyral resin
A mixture of resins can be used. Preferred among these
New products are polyurethane resin, PVC resin, acrylic
Resin. The binder consists of ferromagnetic powder and non-magnetic powder.
Adsorbed on the surface of these powder particles to improve dispersibility
It is preferable to have a functional group (polar group). Preferred officer
As a functional group, -SO_ThreeM, -SO_FourM, -PO (OM)
₂, -OPO (OM)₂ , -COOM,> NSO_ThreeM,>
NRSO_ThreeM, -NR¹R², -N⁺R¹R²R^ThreeX^-etc
Can be mentioned. Where M is hydrogen or an alkali such as Na or K
Metal, R is an alkylene group, R¹, R², R^ThreeIs an alkyl group
Or a hydroxyalkyl group or hydrogen, X is Cl, Br, etc.
Of halogen. The amount of functional groups in the binder is 10 μeq
/ G to 200 μeq / g, more preferably
30 μeq / g to 120 μeq / g is preferred
Yes. If it is in the said range, a dispersibility is favorable. In addition to the adsorptive functional group, the binder includes isocyanate.
Reacts with nate curing agents to form a cross-linked structure to improve coating strength
In order to make functional groups with active hydrogen such as -OH group
It is preferable to give. The amount is 0.1 meq / g
It is preferably ˜2 meq / g. Binder molecular weight
Is a weight average molecular weight of 10,000 to 200,000
And more preferably 20000 to 10,000.
0 is appropriate. If it is 10,000 or more,
High coating strength and excellent durability, no more than 200000
For example, the dispersibility is good. Polyurethane resin as a preferred binder
For example, “Polyurethane resin handbook” (Takashi Iwata
Oji, 1986 Nikkan Kogyo Shimbun)
Usually, long-chain diols and short-chain diols (called chain extenders)
Addition weight of diisocyanate compound)
It can be obtained by combination. As long-chain diol,
Polyester diol having a molecular weight of 500 to 5000, poly
Ether diol, polyether ester diol, polyester
Recarbonate diol, polyolefin diol, etc.
Is used. Depending on the type of this long-chain polyol,
Polyurethane resins that can be used include polyester urethane and poly
Ether urethane, polyetherester urethane, polyester
It is called recarbonate urethane. Polyester diols are adipic acid,
Aliphatic dibasic acids such as vasic acid and azelaic acid, isophthalic acid
Luric acid, orthophthalic acid, terephthalic acid, naphthalenedica
Polycondensation of aromatic dibasic acids such as rubonic acid with glycols.
Can be obtained by: As glycol component
Tylene glycol, 1,2-propylene glycol,
1,3-propanediol, 1,4-butanediol,
1,5-pentanediol, 3-methyl-1,5-pen
Tandiol, 1,6-hexanediol, 2,2-di
Methyl-1,3-propanediol, 1,8-octane
Diol, 1,9-nonanediol, cyclohexanedi
All, cyclohexanedimethanol, bisphenol hydride
Nord A etc. are mentioned. Also polyester diol
In addition, ε-caprolactone, γ-valerolactone
Polycaprolactone dio obtained by ring-opening polymerization of lactone
And polyvalerolactone diol may also be used.
it can. Polyester diol is resistant to hydrolysis
Obtained from materials with branched side chains, aromatic and alicyclic materials
Those are preferred. Polyether diols include polyethylene
Lenglycol, polypropylene glycol, polytet
Ramethylene glycol, bisphenol A, bisphe
Nord S, Bisphenol P, Hydrogenated Bisphenol A
Such as aromatic glycols and alicyclic diols
Alkylene oxides such as oxides and propylene oxide
Examples include addition polymerization of the side. These long chain diols are of multiple types.
Can be used in combination or mixed. Short chain diol
Is a glycol component of the above polyester diol
You can choose from the same group of compounds as illustrated
The Also, trifunctional or higher polyhydric alcohols such as trimethyl
Roll ethane, trimethylolpropane, pentaerythris
When used in small amounts with ritole, etc., branched polyureta
Resin is obtained, and the viscosity of the solution is reduced.
Isocyanate curing by increasing the OH group at the end of
Curability with the agent can be increased. As the diisocyanate compound, MDI
(Diphenylmethane diisocyanate), 2,4-TD
I (tolylene diisocyanate), 2,6-TDI,
1,5-NDI (Naphthalene diisocyanate), TO
DI (tolidine diisocyanate), p-phenylene di-
Isocyanate, XDI (Xylylene Diisocyanate
G) aromatic diisocyanate, transcyclohe
Xan-1,4-diisocyanate, HDI
Chirene diisocyanate), IPDI (isophorone dii)
Socyanate), H₆XDI (hydrogenated xylylene range
Socyanate), H_{1 2}MDI (hydrogenated diphenyl meta
Aliphatic and alicyclic diisocyanates
Nate and the like can be used. Long chain diol / short chain in polyurethane resin
The composition of the diol / diisocyanate is (80-15 layers)
%) / (5-40% by weight) / (15-50% by weight)
Preferably there is. Urethane group concentration of polyurethane resin
The degree is preferably 1 meq / g to 5 meq / g
More preferably 1.5 to 4.5. Ureta
If the base concentration is 1 meq / g or more, the mechanical strength is high.
If it is 5 meq / g or less, the solution viscosity is appropriate and the minute
Good dispersibility. Glass transition temperature of polyurethane resin
Is preferably 0 ° C to 200 ° C, 40 ° C to 16 ° C.
More preferably, it is 0 ° C. Glass transition temperature 0 ° C
If it is above, it is excellent in durability, and if it is 200 ° C. or less,
High calender moldability and good electromagnetic conversion characteristics.
The aforementioned adsorption functional groups (polar groups) are introduced into the polyurethane resin.
As a method of entering, a functional group is a monomer of a long-chain diol.
Method used for a part of the product, Method used for a part of the short-chain diol
After polymerizing polyurethane and polyurethane, the polar group is introduced by polymer reaction
Can be used As the vinyl chloride resin, vinyl chloride resin is used.
Copolymers of monomers with various monomers are used.
The Copolymerization monomers include vinyl acetate and propionic acid
Fatty acid vinyl esters such as vinyl, methyl (meth)
Acrylate, ethyl (meth) acrylate, isopropyl
Pill (meth) acrylate, butyl (meth) acrelan
Acrylates such as benzyl (meth) acrylate
, Methacrylates, allyl methyl ether, allyl
Ethyl ether, allyl propyl ether, allyl buty
Alkyl allyl ethers such as ruether
Tylene, α-methylstyrene, vinylidene chloride, acrylo
Nitrile, ethylene, butadiene, acrylamide, and more
Vinyl alcohol as a copolymerizable monomer with functional groups
2-hydroxyethyl (meth) acrylate, polyester
Tylene glycol (meth) acrylate, 2-hydroxy
Cypropyl (meth) acrylate, 3-hydroxypro
Pill (meth) acrylate, polypropylene glycol
(Meth) acrylate, 2-hydroxyethyl allyl ester
Ether, 2-hydroxypropyl allyl ether, 3-
Hydroxypropyl allyl ether, p-vinyl pheno
, Maleic acid, maleic anhydride, acrylic acid, meta
Crylic acid, glycidyl (meth) acrylate, allylic
Lysidyl ether, phosphoethyl (meth) acrelane
, Sulfoethyl (meth) acrylate, p-styrene
Use sulfonic acids and their Na and K salts.
You can. (Meth) acrylate is acrylate.
And / or at least one of
Means contained. Vinyl chloride monomer in vinyl chloride resin
The composition is preferably 60 to 95% by weight. 6
If it is 0% or more, the mechanical strength is high, and if it is 95% or less.
For example, solvent solubility is high, solution viscosity is appropriate, and dispersibility is good.
Is good. Adsorption functional group (polar group), polyisocyanate
Preferred amount of functional group for enhancing curability with a series curing agent
Is as described above. Method for introducing these functional groups
May be copolymerized with the above functional group-containing monomer,
After copolymerization of vinyl chloride resin, the functional group
May be introduced. The degree of polymerization is 200-600
And more preferably 240 to 450.
Is appropriate. If the degree of polymerization is 200 or more, mechanical strength
If it is high and 600 or less, the solution viscosity is appropriate and the dispersion
Good properties. In the present invention, the binder is crosslinked and cured.
Use a curing agent to increase the mechanical strength and heat resistance of the coating.
be able to. A preferred curing agent is polyisocyanate.
Nate compounds. Polyisocyanate compound
Use triisocyanate or higher polyisocyanate.
Are preferred. Specifically, trimethylolpropane (T
MP) 3 mol of TDI (tolylene diisocyanate)
HDI (hexamethylene dii) added to the added compound, TMP
Compound with 3 moles of cyanate) added to TMP and IP
3 mol of DI (isophorone diisocyanate) was added.
Compound, TMP to XDI (Xylylene Diisocyanate
G), adduct type polyiso
Cyanate compound, condensed isocyanurate type 3 of TDI
Of TDI, condensed isocyanurate pentamer of TDI, of TDI
Condensed isocyanurate heptamers, and mixtures thereof, H
Isocyanurate type condensate of DI, isocyanurate of IPDI
Examples include nurate condensates, and crude MDI.
It is done. Among these, preferred are TMP and TDI.
Isocyanurate form of TDI
Such as a trimer. In addition to isocyanate curing agents, electron beam
Or use radiation curable curing agents such as ultraviolet rays.
It can also be an acryloyl group or
2 or more, preferably 3 methacryloyl groups in the molecule
The curing agent having the above can be used. For example, TMP
(Trimethylolpropane) triacrylate, pen
Taerythritol tetraacrylate, urethane
Examples include related oligomers. In this case, curing
(Meth) acryloyl group introduced into binders in addition to adhesives
It is preferable to do. When using UV curable curing agents
In addition, a photosensitizer is used in combination. Hardeners are many
If the amount is too high, the dispersibility will decrease, so the binder will be 100 parts by weight.
It is preferable to add from 0 to 80 parts by weight. Ferromagnetic material used in the magnetic recording medium of the present invention
The powder is ferromagnetic iron oxide, cobalt-containing ferromagnetic iron oxide or
Can be ferromagnetic alloy powder, S_BETSpecific surface area is 4
0-80m²/ G, preferably 50-70 m²/ G
It is appropriate. Crystallite size is 12-25n
m, preferably 13 to 22 nm, particularly preferably
It is suitable that it is 14-20 nm. The major axis length is 0.
It is 05-0.25 micrometer, Preferably it is 0.07-0.
2 μm, particularly preferably 0.08 to 0.15 μm
It is appropriate that Ferromagnetic alloy powder is F
e, Ni, Fe-Co, Fe-Ni, Co-Ni, Co
-Ni-Fe etc., 20% by weight or less of metal component
Within the range of aluminum, silicon, sulfur, scandium
Titanium, vanadium, chromium, manganese, copper, zinc
Lead, yttrium, molybdenum, rhodium, parasium
Gold, tin, antimony, boron, barium, tinta
Ru, tungsten, rhenium, silver, lead, phosphorus, lanta
, Cerium, praseodymium, neodymium, tellurium, bis
Mention may be made of alloys containing masses. Also ferromagnetic
Gold powder containing a small amount of water, hydroxide or oxide
Anyway. The manufacturing methods for these ferromagnetic powders are already public.
It is also known about the ferromagnetic powder used in the present invention.
It can be manufactured according to the method. Ferromagnetic powder shape
Is not particularly limited, but usually acicular, granular, dice,
Rice grains and plates are used. Especially needle-shaped
The ferromagnetic powder is preferably used. The above resin component, curing agent and ferromagnetic powder
Usually used in the preparation of the magnetic layer coating solution.
Ruethyl ketone, dioxane, cyclohexanone, acetic acid
Kneaded and dispersed with a solvent such as ethyl to form a magnetic layer coating solution.
The The kneading and dispersing can be performed according to a usual method.
The magnetic recording medium of the present invention comprises the above magnetic material on a nonmagnetic support.
Binder containing polyurethane resin used for layer and non-magnetic powder
Or a non-magnetic or magnetic under layer made of magnetic powder
May be. Non-magnetic powder is metal oxide, metal carbonate
Salt, metal sulfate, metal nitride, metal carbide, metal sulfide
It is possible to select from inorganic compounds such as Inorganic compounds
For example, α-alumina having an α conversion rate of 90 to 100%,
β-alumina, γ-alumina, silicon carbide, black oxide
, Cerium oxide, α-iron oxide, corundum, silicon nitride
Elemental, titanium carbide, titanium oxide, silicon dioxide, acid
Tin, magnesium oxide, tungsten oxide, dioxide
Luconium, boron nitride, zinc oxide, calcium oxide,
Calcium sulfate, barium sulfate, molybdenum disulfide, etc.
Can be used alone or in combination. Especially preferred is
Titanium dioxide, zinc oxide, iron oxide, barium sulfate
More preferred is titanium dioxide. these
The average particle size of the non-magnetic powder is 0.005 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. Non-magnetic powder
It is particularly preferable that the average particle size is 0.01 to 0.2 μm.
That's right. It is particularly preferred that the pH of the non-magnetic powder is between 6-9
preferable. Specific surface area of non-magnetic powder is 1-100m²/ G
 , Preferably 5-50m²/ G, more preferably 7 to
40m²/ G is appropriate. Non-magnetic powder
The crystallite size is preferably 0.01 μm to 2 μm.
Yes. Oil absorption using DBP is 5-100ml / 100
g, preferably 10-80 ml / 100 g, more preferred
Or 20 to 60 ml / 100 g.
The The specific gravity is 1 to 12, preferably 3 to 6. Shape is
Any of a needle shape, a spherical shape, a polyhedron shape, and a plate shape may be used. These nonmagnetic powders are made of Al.₂O_Three, SiO
₂TiO₂, ZrO₂, SnO₂, Sb₂O_ThreeZnO
It is preferable to surface-treat with. Especially preferred for dispersibility
Things are Al₂O_Three, SiO₂TiO₂, ZrO₂In
More preferred is Al.₂O_Three, SiO₂, ZrO
₂It is. These may be used in combination or alone
It can also be used. In addition, the table co-precipitated according to the purpose
A surface treatment layer may be used, or after first treating with alumina
The method of treating the surface layer with silica or vice versa
You can also take the law. In addition, the surface treatment layer depends on the purpose.
It can be made porous layer, but it is better to be homogeneous and dense.
Generally preferred. This is used when the lower coating layer is a magnetic layer.
Examples of magnetic powders that can be used are γ-Fe₂O_ThreeCo modification
γ-Fe2O_Three, An alloy mainly composed of α-Fe, CrO₂
Etc. are used. In particular, Co-modified γ-Fe₂O_ThreeIs preferred
Yes. The ferromagnetic powder used in the lower magnetic layer of the present invention is
Same composition and performance as the ferromagnetic powder used in the magnetic layer
It is preferable to have. However, depending on the purpose, upper and lower layers
It is known that the performance can be changed by the above. For example,
In order to improve long wavelength recording characteristics, H of the lower magnetic layer
c should be set lower than that of the upper magnetic layer.
In addition, Br of the lower magnetic layer is higher than that of the upper magnetic layer.
Is effective. Other than that, known multilayer structures
Advantages can be imparted by taking the composition. In the present invention, the magnetic layer or the lower coating layer
Other additives used include lubrication effect, antistatic
Use one with a stopping effect, dispersion effect, plasticizing effect, etc.
Can. Molybdenum disulfide, tungsten disulfide
, Graphite, boron nitride, graphite fluoride, silicon
Oil, silicone with polar group, fatty acid-modified silicone
Fluorine, silicone, fluorine-containing alcohol,
Fluorine-containing ester, polyolefin, polyglycol
, Alkyl phosphates and their alkali metals
Salts, alkyl sulfates and alkali metal salts thereof,
Polyphenyl ether, fluorine-containing alkyl sulfate esthetics
And its alkali metal salts, C10-24 unsaturated
Monobasic fats that may contain sum bonds or may be branched
Fatty acids and their metal salts (Li, Na, K, Cu
Etc.) or containing an unsaturated bond having 12 to 22 carbon atoms
Can also be branched monovalent, bivalent, trivalent, tetravalent,
Pentavalent, hexahydric alcohol, C12-22 unsaturated bond
Alkoxyalkoxy that may contain or be branched
Including unsaturated bonds of 10 to 24 carbon atoms,
Monobasic fatty acid which may be branched and 2-12 carbon atoms
Monovalent, which may contain unsaturated bonds or may be branched,
One of divalent, trivalent, tetravalent, pentavalent, hexavalent alcohol
Mono-fatty acid ester or di-fatty acid esthetic
Or tri-fatty acid ester, alkylene oxide polymerization
Fatty acid ester of monoalkyl ether, 2 carbon atoms
-22 fatty acid amide, C8-22 aliphatic amine
Etc. can be used. Specific examples of these include laurin.
Acid, myristic acid, palmitic acid, stearic acid, behehe
Acid, butyl stearate, oleic acid, linoleic acid,
Linolenic acid, elaidic acid, octyl stearate,
Amyl tearate, isooctyl stearate, myris
Octyl tinate, butoxyethyl stearate, anhy
Drosorbitan monostearate, anhydrosorbita
Distearate, anhydrosorbitan tristeale
And oleyl alcohol, lauryl alcohol
It is done. Further, alkylene oxide type, glycerin
, Glycidol, alkylphenol ethylene
Nonionic surfactants such as oxide adducts, cyclic amines,
Ester amide, quaternary ammonium salts, hydantoy
Derivatives, heterocycles, phosphonium or sulfonium
, Etc., cationic surfactants, carboxylic acids, sulfones
Acid, phosphoric acid, sulfate ester group, phosphate ester group, etc.
Anionic surfactants containing acidic groups, amino acids, amino
Sulfonic acids, amino alcohol sulfuric acid or phosphoric acid
There are also amphoteric surfactants such as stealth and alkylbedine type
Can be used. For these surfactants, see “Surface Activity”.
It is described in detail in "Handbook of Sexual Agent" (issued by Sangyo Tosho Co., Ltd.)
ing. These lubricants and antistatic agents are not necessarily pure.
Rather than the main components, isomers, unreacted materials, side-reacted materials,
Impurities such as decomposition products and oxides may be included. This
The content of these impurities is preferably 30% by weight or less.
More preferably, it should be 10% by weight or less.
Is appropriate. These lubrications used in the present invention
The type and amount of the agent and surfactant are required for the nonmagnetic layer and magnetic layer
It can be used as needed. For example, non-magnetic layer,
Bleeding to the surface using fatty acids with different melting points in the magnetic layer
Controlling the surface using esters with different boiling points and polarities
Adjust the amount of surfactant to control bleeding
And improve the stability of the coating, the amount of lubricant added is non-magnetic
It may be possible to improve the lubrication effect by increasing the number of layers,
Of course, it is not limited to the example shown here. Also
All or part of the additives used in the present invention are
Any process during the production of the coating solution for the magnetic layer or lower coating layer
It may be added as much as possible. For example, ferromagnetic powder before kneading process
Kneading with ferromagnetic powder, binder and solvent
If added in the process, if added in the dispersion process, after dispersion
In some cases, it may be added immediately before coating. As these lubricants used in the present invention,
Is specifically made by Nippon Oil & Fats: NAA-102, castor oil
Hardened fatty acid, NAA-42, cationic SA, Naimine
L-201, Nonion E-208, Anon BF, Anon
LG, butyl stearate, butyl laurate, Elka
Acid, manufactured by Kanto Chemical: Oleic acid, Takemoto Yushi: FAL-2
05, FAL-123, made by Shin Nippon Chemical Co., Ltd .: NJ
L, Shin-Etsu Chemical: TA-3, Lion Armor: A
-Mide P, Lion Corporation Duomin TDO, Nissin
Oil: BA-41G, Sanyo Chemical: Profan 2012
E, New Paul PE61, Ionette MS-400
And so on. The lower layer coating solution prepared from the above materials
If necessary, apply it on a nonmagnetic support and then apply a magnetic layer.
A cloth layer is applied to form a magnetic layer. Magnetic recording medium of the present invention
The manufacturing method of the body is, for example, a non-magnetic support under running
Magnetic layer coating solution on the surface, preferably the thickness of the magnetic layer after drying
0.05 to 5 μm, more preferably 0.07 to 1 μm
Apply as follows. Here, multiple magnetic layer coating solutions are
Subsequent or simultaneous multilayer coating may be used, the lower layer coating solution and the magnetic layer
The coating solution may be applied successively or simultaneously. Magnetic field
As a coating machine for applying the coating liquid for the adhesive layer or the lower layer coating liquid,
Air doctor coat, blade coat, rod coat
, Extrusion coating, air knife coating, squeeze coat
, Impregnation coat, reverse roll coat, transfer
-Roll coat, gravure coat, kiss coat, cast
To coat, spray coat, spin coat etc. are available
The For example, General Technology Center Co., Ltd.
-"Latest coating technology" (May 3, 1983)
1 day). The present invention is applied to a magnetic recording medium having two or more layers.
In the case of application, the following are examples of the application device and method.
Can be proposed. (1) Gravity generally applied in application of magnetic layer coating solution
A, roll, blade, extrusion coating equipment
First, apply the lower layer and place the lower layer in an undried state.
JP-B-1-46186, JP-A-60-238
179, JP-A-2-265672, etc.
Support-type extrusion coating like
The upper layer is applied using an apparatus. (2) JP-A-63-88080, JP-A-2-17
No. 971 and JP-A-2-265672.
One of the two coating liquid passage slits
The upper and lower layers are applied almost simultaneously by the application head. (3) It is disclosed in Japanese Patent Laid-Open No. 2-174965.
Extrusion coating with a backup roll like
The upper and lower layers are applied almost simultaneously with a cloth device. Application of magnetic layer to nonmagnetic support used in the present invention
Backcoat layer (backing) on the surface where no liquid is applied
Layer) may be provided. Backcoat layer is non-magnetic
The surface of the conductive support that has not been coated with the magnetic layer coating solution is polished.
Materials, antistatic agents and other particulate components and binders in organic solvents
It is provided by applying a dispersed back coat layer forming coating solution
Layer. Various inorganic pigments and carbon as particulate components
Black can be used.
Trocellulose, phenoxy resin, vinyl chloride resin,
Use resins such as polyurethane alone or in combination.
Can be used. Polyure used for backcoat layer
Use the polyurethane resin of the present invention as a tan resin
Thus, the durability can be further improved. Na
Magnetic layer coating solution and back coat layer type for non-magnetic support
An adhesive layer may be provided on the application surface of the composition coating solution.
Yes. Magnetic layer formed by applying magnetic layer coating solution
Magnetic field orientation treatment of ferromagnetic powder contained in the magnetic layer
After applying, it is dried. After being dried in this way,
A surface smoothing treatment is applied to the magnetic layer. For surface smoothing treatment,
For example, a super calendar roll is used.
Removal of solvent during drying by surface smoothing treatment
The vacancies caused by the disappearance of the ferromagnetic powder in the magnetic layer
Magnetic recording medium with high electromagnetic conversion characteristics due to improved filling rate
You can get a body. As a calendar processing role
Is heat resistant such as epoxy, polyamide, polyamideimide
A plastic roll can be used. Also,
It can also be treated with a metal roll. The magnetic recording medium of the present invention has a surface centerline flat surface.
The average roughness is 0.1 to 0.1 at a cutoff value of 0.25 mm.
5 nm, preferably in the range of 1-4 nm, very excellent
The smooth surface should be suitable for high-density recording.
Preferred as a magnetic recording medium. For example,
Select and form specific ferromagnetic powder and binder as described above
By applying the above calendar treatment to the magnetic layer
Is called. Calendar processing, calendar roll temperature
Is in the range of 60-100 ° C, preferably 70-100 ° C
, Particularly preferably in the range of 80 to 100 ° C.,
The pressure is in the range of 100 to 500 kg / cm, preferably 2
The range of 00 to 450 kg / cm, particularly preferably 300
It is preferable to carry out under conditions that are in the range of ~ 400 kg / cm
That's right. The resulting magnetic recording medium can be cut using a cutter, etc.
It can be cut into a desired size and used. [0042] The following examples illustrate the present invention.
The present invention is not limited to these. Examples
The indication of “parts” in the figure indicates “parts by weight”. [Polyester resin solution A] Thermometer, stirrer, reflux cooling
In a reaction vessel equipped with a tube and a distillation tube.
45 mol of chill, dimethyl 2,6 naphthalenedicarboxylate
40 moles, 5 sodium dimethyl dimethyl sulfoisophthalate
5 mol, ethylene glycol 52 mol, diethylene glycol
5 mol of coal, 28 mol of triethylene glycol, bis
39 mol of phenol A ethylene oxide adduct, tet
Rabutyl titanate, 0.1 parts, zinc acetate 0.1 parts
And transesterification reaction at 180 to 210 ° C for 5 hours
Went. The reaction system is then brought to 5 mmHg over 20 minutes.
The pressure was reduced to 280 ° C. during this time. 280 more
The polycondensation reaction was carried out for 60 minutes at a temperature of 0.1 mmHg. Gain
Polyester resin composition, glass transition temperature, weight
Table 1 shows the average molecular weight and the amount of elution into the solvent. The analysis is
The following method was used. ・ Polyester composition: NMR analysis Glass transition temperature: Using a dynamic viscoelasticity measuring device, 2 ° C /
Measured at 110Hz, partial temperature rise -Weight average molecular weight: GPC using eluent DMF, standard
It calculated | required in restyrene conversion. ・ Elution amount to solvent: Polyester on the substrate of PET film
A film cast of tellurium is M at a liquid temperature of 25 ° C.
EK / cyclohexanone = 1/1
Immerse for 0 seconds, take it out and measure the eluted weight
1 cm surface area²What was converted to per. Furthermore, polyester resin is mixed in ethanol / water = 1/1
The polymer is dissolved in a solvent so that the solid content is 10% by weight.
A steal resin solution A was obtained. [Polymerization examples of polyester resin solutions B to L]
Table with the same polymerization conditions as when Reester resin solution A was obtained
The polyester resin described in 1 is polymerized and dissolved in a solvent,
Polyester resin solutions B to L were obtained. [Example 1]Preparation of magnetic layer coating solution for upper layer Ferromagnetic alloy powder (composition: Fe 89 atm%, Co 5a
tm%, Y 6 atm%, Hc 159 kA / m (200
0 Oe), crystallite size 15 nm, BET specific surface area
59m²/ g, major axis diameter 0.12 μm, acicular ratio 7, σs 1
50A ・ m²/ Kg (150emu / g)) Open 100 parts
Crush for 10 minutes with a kneader and then S_ThreeONa content
Riurethane solution (solid content 30%, SO_ThreeNa content 70μ
eq / g, weight average molecular weight 40,000) 10 parts (solid content) added
Add 30 parts of cyclohexanone and knead for 60 minutes.
did. Then       Abrasive (Al₂O_Three, Particle size 0.3 μm) 2 parts       2 parts of carbon black (particle size 40μm)       Methyl ethyl ketone / toluene = 1/1 200 parts Was added and dispersed in a sand mill for 120 minutes. to this       Polyisocyanate 5 parts (solid content)               (Japan Polyurethane Coronate 3041)        Butyl stearate 2 parts       1 part of stearic acid        50 parts of methyl ethyl ketone After stirring for another 20 minutes, the average of 1 μm
Filtration using a filter having a pore size, magnetic layer coating solution
Was prepared. [0045]Preparation of nonmagnetic layer coating solution for lower layer α-Fe₂O_Three(Average particle size 0.15 μm, S_BET52m²/
g, Surface treatment Al₂O_Three, SiO₂PH 6.5-8.
0) Crush 100 parts with an open kneader for 10 minutes,
Next, PVC / Vinyl acetate / Glycidyl methacrylate = 86/9
/ 5 copolymer with hydroxyethyl sulfonate
Compound with added lithium salt (SO_ThreeNa = 6 × 10^-Fiveeq
/ G, epoxy = 10^-3eq / g, Mw 30,000)
7.5 parts and SO_ThreeNa-containing polyurethane solution (solid
30% min, SO_ThreeNa content 70 μeq / g, weight average
10 parts (solid content) is added, and cyclohexa is added.
30 parts of non was added and kneaded for 60 minutes. Then   Methyl ethyl ketone / cyclohexanone = 6/4 200 parts Was added and dispersed in a sand mill for 120 minutes. to this       Polyisocyanate 5 parts (solid content)               (Japan Polyurethane Coronate 3041)       Butyl stearate 2 parts       1 part of stearic acid       50 parts of methyl ethyl ketone After stirring for another 20 minutes, the average of 1 μm
Filtration using a filter having a pore size, coating solution for lower layer
Was prepared. Next, polyester resin solutions shown in Table 1
Coil bar so that the thickness after drying A is 0.5μm
Is applied to the support surface shown in Table 2 with a thickness of 7 μm.
After drying, apply a nonmagnetic layer on the undercoat layer
The liquid is further dried so that the thickness after drying becomes 1.5 μm.
Immediately after that, the thickness after drying the magnetic layer coating solution is 0.05 μm.
Apply multiple layers simultaneously using a reverse roll.
It was. Non-magnetic support coated with magnetic layer coating solution is magnetic coated
With a 0.5T (5000 Gauss) Co magnet in an undried state
Magnetic field orientation with 0.4T (4000 Gauss) solenoid magnet
Apply the applied metal roll-metal roll-metal low
Rule-Metal roll-Metal roll-Metal roll-Metal roll
100m / m for calendar processing by combination of
in, after performing at a linear pressure of 300 kg / cm and a temperature of 90 ° C.
A magnetic tape was obtained by slitting to a width of 3.8 mm. Examples 2 to 9 and Comparative Examples 1 to 7 are shown in Table 2.
The polyester resin solution shown in Table 2 is placed on the support.
The same as in Example 1 except that it was applied as a coating agent
Magnetic tape was produced by the method. Measuring method Coating smoothness Digital Instrument Nanoscope III (AFM: Atom
SiN probe with a ridge angle of 70 #
10μm square (100μm²) Minute protrusion height
The number of protrusions was measured every 5 nm up to 20 nm, and Comparative Example 1
Is shown as a relative value where 100 is 100. Electromagnetic conversion characteristics Single frequency signal of 4.7MHz with DDS4 drive
Recording was performed at the optimum recording current, and the reproduction output was measured. Comparison
The reproduction output of Example 1 is shown as a relative value with 0 dB. Preservation adhesive One tape in an incassed state at 60 ° C and 90% RH environment
After storing for a month, unwind the tape and visually determine the adhesiveness
And the adhesive between the front and back of the tape was not seen
Was evaluated as “◯”, and the case where adhesion occurred was evaluated as “x”. Running durability DDS4 dry the magnetic layer surface at 50 ° C and 20% RH
Contact with the guide pole used in the
Multiply g (T1) and repeat at a speed of 8 mm / sec.
000 passes, and the friction coefficient in the first pass is 1.
The friction coefficient at the 1000th pass is expressed as a relative value and the friction increases
It was. Furthermore, the differential interference optical microscope is used to observe the surface of the magnetic layer after running.
And evaluated with the following ranks. Excellent: No scratches are seen. Poor: Scratches are seen. [0048] [Table 1][0049] [Table 2] Evaluation results SO_ThreeM-containing dibasic acid component for all dibasic acid components
Polyester resin solution A containing 15 to 40 mol%,
B, C, G, and SO_ThreeM-containing glycol component
Polyester containing 15 to 40 mol% of the recall component
Implementation using Stealth resin solutions D-F as primer
Examples 1 to 9 are all excellent in coating film smoothness and special in electromagnetic conversion.
It was highly resistant and no sticking to storage occurred. Also, the friction coefficient
There is little increase, and the film damage is seen even after running 1000 passes.
The running durability was excellent. SO_ThreeM-containing dibasic
Poly containing 10 mol% of acid component with respect to the total dibasic acid
Ratio in which the ester resin solution H is coated on a PET support
Comparative Example 1, Comparative Example 6 coated on a PEN support, and
Comparative Example 7 coated on the imide support is all examples.
Compared with the coating film smoothness and electromagnetic conversion characteristics, it was inferior. Also,
In Comparative Example 1, adhesion between the front surface and the back surface of the tape was not achieved after storage.
I started. This is a sulfonic acid metal salt in polyester resin
Since the base amount is small, the hydrophilicity is low and it is applied on the undercoat layer.
Polyester resin in non-magnetic layer coating solution and magnetic layer coating solution
Because it melted and deposited on the surface of the magnetic layer after long-term storage.
It is believed that there is. In Comparative Example 1, the friction coefficient is increased.
There are many, paint film damage is seen after 1000 passes,
The running durability was inferior. SO_ThreeM-containing glycol component
Containing 10 mol% of the total glycol component
Comparative example in which ester resin solution was coated on PET support
2 is inferior to Examples in both coating film smoothness and electromagnetic conversion characteristics.
In addition, there is adhesion between the front and back of the tape after storage.
I started. In addition, the friction coefficient is greatly increased, and 1000 pass running
Damage to the paint film is observed after the run, and the running durability is inferior
It was. SO_ThreeM-containing dibasic acid component to all dibasic acid components
Polyester resin solution J containing 45 mol%
Comparative Example 3 coated on ET support and SO_ThreeM containing G
45 mol% of the recall component with respect to the total glycol component
The containing polyester resin solution K is placed on a PET support.
The applied Comparative Example 4 was smoother and smoother than the Examples.
Inferior to the electromagnetic conversion characteristics, and after storage, the tape
Adhesion between the front and back surfaces occurred. This is a metal sulfonate
Excessive groups increase the hygroscopicity of the undercoat layer and
This is thought to be due to a decrease in storage stability under humidity. Ma
In addition, the coefficient of friction increased greatly, and it was applied after 1000 passes.
Film damage was seen and running durability was inferior. SO_Three
M-containing dibasic acid and SO_ThreeContains M-containing glycol component
Polyester resin solution L is applied on the PET support
Comparative Example 5 was inferior particularly in smoothness and electromagnetic conversion characteristics.
It was. [0051] According to the present invention, the coating film has high smoothness and electromagnetic deformation.
A magnetic recording medium having excellent conversion characteristics can be obtained. Main departure
The bright magnetic recording medium has high durability in repeated running,
In addition, no adhesive failure occurs after storage, making it suitable for long-term storage
The

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4J029 AA03 AC02 AE03 AE05 AE11                       BA02 BA03 BA04 BA05 BA08                       BA10 BB13A BD04A BD07A                       BF09 BF18 BF24 BF26 BH02                       CA02 CA04 CA06 CB04A                       CB05A CB06A CB10A CC05A                       CC06A CD03 CF08 CH02                       DB02 JB131 JB171 JF181                       JF321 KD02 KD07 KE02                       KE05                 5D006 CA01

Claims (1)

What is claimed is: 1. A magnetic recording medium comprising an undercoat layer and at least one magnetic layer containing a ferromagnetic powder and a binder in this order on a nonmagnetic support, wherein the undercoat layer comprises Contains dibasic acid component containing 15-40 mol% sulfonic acid metal base with respect to dibasic acid component and / or glycol component containing 15-40 mol% sulfonic acid metal base with respect to total glycol component A magnetic recording medium comprising a polyester copolymer.