JPH09153216A - Production of magnetic recording medium and its producing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device to produce a magnetic recording medium by which a magnetic powder in a magnetic coating film can be easily oriented along the longitudinal direction of a nonmagnetic supporting body even on both side edges of the nonmagnetic supporting body and by which a magnetic recording medium having an excellent squareness ratio in the longitudinal direction of the nonmagnetic supporting body all over the width of the nonmagnetic supporting body can be produced. SOLUTION: In this method, a magnetic recording medium is produced by applying a magnetic coating liquid to form a magnetic coating film 5 on a long nonmagnetic base body 1 which is continuously travelled, orienting the magnetic powder in the magnetic coating film 5, and drying the coating film 5. A magnetic field for orientation is produced by a solenoid coil 8 having the tunnel width >=1.15 time as the width of the magnetic coating film 5 on the nonmagnetic supporting body 1 so as to orient the magnetic powder in the magnetic coating film 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a magnetic recording medium, and more specifically, to a magnetic powder contained in a magnetic coating film on a non-magnetic support. The present invention relates to a method and an apparatus for producing a magnetic recording medium having excellent orientation by orienting in the longitudinal direction.

[0002]

2. Description of the Related Art A magnetic recording medium such as a magnetic tape is mounted on a long non-magnetic support which is continuously conveyed in the longitudinal direction.
A magnetic coating solution containing magnetic powder is applied to form a magnetic coating film, the magnetic coating film is dried, and then cut into a desired size.
Being manufactured. At this time, before the magnetic coating film coated on the non-magnetic support is dried, or while drying the magnetic coating film, a magnetic field is applied in the longitudinal direction of the non-magnetic support,
In general, magnetic powder is oriented in the longitudinal direction of the non-magnetic support to increase the squareness ratio of the magnetic coating film and improve the orientation of the magnetic recording medium. As described above, one or more electromagnets or permanent magnets are used as a means for applying a magnetic field to the magnetic coating film. In the conventional orientation method, for example, at least a pair of long permanent magnets are provided in a direction orthogonal to the transport direction of the non-magnetic support so that the same poles face each other, and a magnetic field is applied to the magnetic coating film. , The magnetic field lines emitted from the permanent magnet are not parallel to the surface of the permanent magnet as they approach the end of the permanent magnet and face outward, so do not use a permanent magnet that is extremely longer than the width of the non-magnetic support. As long as it is difficult to apply a magnetic field parallel to the longitudinal direction of the non-magnetic support to the magnetic coating over the entire width of the non-magnetic support, it is therefore necessary to apply the magnetic field near the center of the non-magnetic support in the width direction. The magnetic powder in the magnetic coating film of can be oriented in the longitudinal direction of the non-magnetic support, but the magnetic powder in the magnetic coating film close to the widthwise side portion of the non-magnetic support can be, as desired, Longitudinal orientation of non-magnetic support Because Rukoto can not, the squareness ratio of the magnetic recording medium obtained by cutting the magnetic layer close to the end portion in the width direction of the nonmagnetic support, could not be improved as desired. The same applies to the case of electromagnets. However, it is uneconomical to use permanent magnets or electromagnets that are much longer than the width of the non-magnetic support, and a solution to them has been desired.

In view of this, in Japanese Patent Laid-Open No. 1-184724, correction magnets are provided on both sides of a non-magnetic support on the downstream side of a magnet that generates a magnetic field for orientation, and a correction magnet is used. The magnetic field prevents the magnetic field lines of the magnetic field generated by the magnet for magnet orientation from going outward at both edges, and the magnetic coating film is oriented so that the magnetic powder in the magnetic coating film is not removed. A method of manufacturing a magnetic recording medium has been proposed in which the non-magnetic support is oriented in the longitudinal direction over the entire width of the magnetic support.

[0004]

However, in this method, the position of the magnet for correction and the strength of the magnetic field generated by the magnet for correction are set as desired according to the strength of the magnetic field for orientation. Is not easy to set, and also
There has been a problem that the orientation of the orientation magnetic field at both edges of the non-magnetic support cannot be completely corrected in the longitudinal direction of the non-magnetic support. The present invention, even in the both side edges of the non-magnetic support, the magnetic powder in the magnetic coating film,
Manufacture of magnetic recording medium capable of being oriented in the longitudinal direction of a non-magnetic support and capable of producing a magnetic recording medium having an excellent squareness ratio in the longitudinal direction of the non-magnetic support over the entire width of the non-magnetic support It is an object to provide a method and a device.

[0005]

The inventors of the present invention have conducted extensive studies in order to achieve the above object of the present invention, and as a result, the above object of the present invention has been found to be the width of a magnetic coating film on a non-magnetic support. It has been found that this can be achieved by generating a magnetic field for orientation by a solenoid coil having a tunnel width of 1.15 times or more of the above and orienting the magnetic powder in the magnetic coating film. In the present invention, the tunnel width of the solenoid coil means the inner diameter of the solenoid coil in a plane including the surface of the non-magnetic support. In a preferred embodiment of the present invention, the solenoid coil has a tunnel width of 1.2 times or more the width of the magnetic coating film on the non-magnetic support. In a further preferred embodiment of the present invention,
The magnetic powder in the magnetic coating film is oriented by the solenoid coil while drying the magnetic coating film. In a further preferred aspect of the present invention, the magnetic powder in the magnetic coating film is further subjected to a preliminary orientation treatment prior to the orientation treatment by the solenoid coil.

[0006] In a further preferred aspect of the present invention, the magnetic powder in the magnetic coating film is preliminarily dried after the magnetic powder in the magnetic coating film is subjected to a pre-orientation treatment. It is configured to be oriented by a solenoid coil. In a further preferred aspect of the present invention, after the magnetic powder in the magnetic coating film is oriented by the solenoid coil, the magnetic coating film is further dried. In the present invention, the pre-orientation treatment can be performed by using one or more pairs of permanent magnets or one or more solenoid coils. In the present invention, the magnetic powder contained in the magnetic coating film is not particularly limited, but for example, γ-iron oxide ferromagnetic powder, cobalt-containing γ-iron oxide ferromagnetic powder, ferromagnetic metal or alloy. Conventionally known ferromagnetic powders such as powder, nitride-based ferromagnetic powder, barium ferrite, and strontium ferrite can be used.
Among these, a particularly preferable one is a ferromagnetic alloy powder containing α-Fe as a main component. In addition to the above atoms, these ferromagnetic metal powders include Al, Si, S, Sc and C.
a, Ti, V, Cr, Y, Mo, Rh, Pd, Ag, S
n, Sb, Te, Ba, Ta, W, Re, Au, Hg,
Pb, Bi, La, Ce, Pr, Nd, P, Co, M
Atoms such as n, Zn, Ni, Sr and B may be included. Especially, Al, Si, Ca, Y, Ba, La, N
d, Co, Ni, and B are important as atoms contained in addition to α-Fe. These ferromagnetic metal powders may be previously treated with a dispersant, a lubricant, a surfactant, an antistatic agent, etc., which will be described later, before the dispersion. Specific examples of these magnetic powders include, for example, JP-B-44-14090, JP-B-45-18372, JP-B-47-22062, JP-B-47-22513,
Japanese Patent Publication No. 46-28466, Japanese Publication No. 46-38755, Japanese Publication No. 47-4286
Issue, Japanese Examined Sho 47-12422, Examined Sho 47-17284, Examined Sho 47-1
8509, Japanese Examined Sho 47-18573, Japanese Examined Sho 39-10307, Japanese Examined Sho
48-39639, U.S. Pat.Nos. 3,026,215 and 3,03
1,341, 3,100,194, 3,242,005, 3,
No. 389,014.

The ferromagnetic metal powder may contain small amounts of hydroxides or oxides. The ferromagnetic metal powder can be obtained by a known manufacturing method, for example,
A method of reducing a complex organic acid salt (mainly oxalate) with a reducing gas such as hydrogen, a method of reducing iron oxide with a reducing gas such as hydrogen to obtain Fe or Fe-Co particles, a metal carbonyl compound Thermal decomposition, a method of reducing by adding a reducing agent such as sodium borohydride, hypophosphite or hydrazine to an aqueous solution of a ferromagnetic metal, fine metal powder by evaporating the metal in a low pressure inert gas The ferromagnetic metal powder obtained by the method of obtaining The ferromagnetic metal powder thus obtained can be subjected to a known gradual oxidation treatment. As the method of gradual oxidation treatment, a method of immersing in an organic solvent and then drying, a method of immersing in an organic solvent and then feeding an oxygen-containing gas to form an oxide film on the surface, and then drying, an organic solvent is used. First, a method of forming an oxide film on the surface by adjusting the partial pressures of oxygen gas and inert gas can be mentioned.
In the ferromagnetic metal powder contained in the magnetic coating film, Hc is usually
1500-4000 oersteds, preferably 180
0-3500 Oersted, more preferably 200
At 0 to 3000 Oersted, the saturation magnetization s is usually
110-190emu / g, preferably 125-180em
u / g, more preferably 130 to 160 emu / g, major axis length is usually 0.03 to 0.25 μm, and preferably,
0.04 to 0.15 μm, more preferably 0.05
~ 0.13 μm, the crystallite size is usually 80-300
Angstrom, preferably 100 to 200 angstrom, more preferably 120 to 190 angstrom. The ferromagnetic metal powder has an acicular ratio of 4 to 1
8 is preferable, More preferably, it is 5-12. The water content of the ferromagnetic metal powder is preferably 0.01 to 2%. It is preferable to optimize the water content of the ferromagnetic metal powder depending on the type of the binder.

The ferromagnetic metal powder in the magnetic coating film of the present invention is B
The specific surface area measured by the ET method is 45 to 80 m ² / g, preferably 50 to 70 m ² / g. 45m ² /
If it is less than g, the noise becomes high, and if it exceeds 80 m ² / g,
It is difficult to obtain a smooth surface, which is not preferable. It is preferable that the pH of the ferromagnetic metal powder be optimized depending on the combination with the binder used. The range is 4 to 12, preferably 6 to 10. For ferromagnetic metal powder,
If necessary, surface treatment may be performed with Al, Si, P, or an oxide thereof. The amount thereof is 0.1 to 10% with respect to the ferromagnetic metal powder, and when the surface treatment is performed, adsorption of a lubricant such as fatty acid is 100 mg / m ² or less, which is preferable. Ferromagnetic metal powder contains soluble N
In some cases, inorganic ions such as a, Ca, Fe, Ni, and Sr are contained, but if the content is 200 ppm or less, the characteristics are not particularly affected. The ferromagnetic metal powder used in the present invention preferably has few voids, and the value is 20% by volume or less, preferably 5% by volume or less. The shape of the ferromagnetic metal powder may be any of acicular, granular, rice granular, and plate-like as long as the characteristics of the crystallite size and the acicular ratio described above are satisfied. SFD of ferromagnetic metal powder is 0.6
In order to achieve the following, it is necessary to reduce the distribution of Hc in the ferromagnetic metal powder. As a method therefor, there are a method of improving the particle size distribution of goethite and a method of preventing sintering of γ-hematite.

In the present invention, the magnetic coating film may contain an abrasive. As the abrasive, α-alumina, β-alumina, silicon carbide, chromium oxide, cerium oxide, corundum, artificial diamond, silicon nitride, titanium carbide, titanium oxide, silicon dioxide having an α conversion of 90% or more,
Known materials having a Mohs hardness of 6 or more, such as boron nitride, can be used alone or in combination, and a composite of these abrasives, that is, an abrasive is surface-treated with another abrasive. It is also possible to use the prepared one. These abrasives may contain compounds or elements other than the main component. The shape of the abrasive is needle-shaped,
It may have a spherical shape or a dice shape, but one having corners is preferable because of high abrasivity. Specific examples of the abrasive used in the present invention include AKP-50 and HIT-50 manufactured by Sumitomo Chemical Co., Ltd., S7 and S-1 manufactured by Nippon Kagaku Kogyo Co., Ltd., 100ED and 140 manufactured by Toda Kogyo Co., Ltd.
ED etc. are mentioned. The abrasive may be added to the magnetic coating solution after being subjected to dispersion treatment with a binder in advance. In the present invention, the magnetic coating film may be a single layer or a multilayer, and may further include a nonmagnetic layer in which a nonmagnetic powder is dispersed in a binder.

When only the magnetic coating is provided on the non-magnetic support, the magnetic coating is coated with an antistatic agent or an abrasive in order to improve the antistatic property and polishing property of the magnetic recording medium. It may be necessary to add a magnetic powder, etc., and the filling rate of the magnetic powder may decrease, but a nonmagnetic layer in which the nonmagnetic powder is dispersed in a binder is provided on the nonmagnetic support, and the magnetic When a coating film is provided, the antistatic property and the polishing property of the magnetic recording medium can be improved by incorporating an antistatic agent or an abrasive in the non-magnetic layer. It is possible to prevent the filling rate of the magnetic powder from decreasing, which is preferable. Preferably, the non-magnetic powder contained in the non-magnetic layer is titanium oxide, barium sulfate, silica,
It is at least one non-magnetic powder selected from α-alumina, zinc oxide, α iron oxide, cerium oxide, tin oxide and zirconia. The particle size of these non-magnetic powders is
It is preferably 0.01 to 2 μm, but non-magnetic powders having different particle sizes may be combined if necessary.
For example, in order to impart conductivity, carbon black may be mixed in an amount of 30 parts by weight or less with respect to 100 parts by weight of the main nonmagnetic powder, and Cr having a large particle size may be used.
₂ O _3, diamond, silicon nitride, as an abrasive or the like SiC, the main non-magnetic powder may be mixed 20 parts by weight or less. The main non-magnetic powder does not necessarily have to be 100% pure, and its surface may be treated with another inorganic compound depending on the purpose.

Specific examples of the non-magnetic powder usable in the present invention include UA5600 manufactured by Showa Denko KK,
UA5605, Sumitomo Chemical Co., Ltd. AKP-20,
AKP-30, AKP-50, HIT-50, HiT-
100, ZA-G1, Toda Kogyo TF-10
0, TF-120: TF-140, TT0-51B, TT0-55A, TT0-55B, T manufactured by Ishihara Sangyo Co., Ltd.
T0-55C, TT0-55S, TT0-55D, FT
-1000, FT-2000, FTL-100, FTL
-200, M-1, S-1, SN-100, Titanium Industry Co., Ltd. ECT-52, STT-4D, STT-30.
D, STT-30, STT-65C, Mitsubishi Metal Co., Ltd. T-1, Nippon Shokubai Chemical Co., Ltd. NS-0, NS
-3Y, NS-8Y and the like. The nonmagnetic powder contained in the nonmagnetic layer is preferably subjected to a surface treatment with an organic substance in order to prevent the fatty acid to be added from adsorbing to the nonmagnetic powder and to improve the wetting with the binder. Examples of the organic substance used for the surface treatment include organic acids having a pKa of 3 or less, epoxy group-containing compounds having a molecular weight of 3000 or less, silane coupling agents, titanate coupling agents, and the like. Specific examples of compounds and treatment methods are disclosed in JP-A-5-
It is disclosed in Japanese Patent No. 182178.

In the present invention, carbon black may be added to the nonmagnetic layer together with the main nonmagnetic powder.
In that case, as the carbon black, a furnace for rubber, a thermal for rubber, a black for color, acetylene black and the like can be used. Carbon black has a specific surface area of 100 to 500 m ² / g, preferably 1
50 to 400 m ² / g, carbon black DBP
The oil absorption is 20 to 400 ml / 100 g, preferably 30 to 200 ml / 100 g. The particle size of carbon black is 5 to 80 mμ, preferably 10 to 50 mμ, and more preferably 10 to 40 mμ. Preferably, the carbon black has a pH of 2 to 1.
0, water content 0.1 to 10%, tap density 0.1
To 1 g / CC. In the present invention, specific examples of carbon black used together with the main non-magnetic powder include BLACKPEARLS manufactured by Cabot Corporation.
2000, 1300, 1000, 900, 800, 88
0,700, VULCANXC-72, Mitsubishi Kasei Kogyo Co., Ltd. # 3250B, # 950B, # 650B, # 9.
70B, # 850B, CONDUCTEXSC, RAVEN 8800, 80, manufactured by Conlon Bia Carbon Co., Ltd.
00, 7000, 5750, 5250, 3500, 21
00, 2000, 1800, 1500, 1255, 12
50, Ketjen Black EC manufactured by Akzo Co., Ltd., and the like. Carbon black which has been surface-treated with a dispersant or grafted with a resin or carbon black whose surface has been partially graphitized can also be used. Further, the carbon black may be dispersed with a binder in advance before being added to the magnetic coating liquid. These carbon blacks can be used alone or in combination with other types of carbon black. When using carbon black, the amount based on the main non-magnetic powder is preferably 0.1 to 30% by weight. Carbon black has the functions of preventing static charge of the non-magnetic layer, imparting light-shielding properties, and improving film strength, but these functions differ depending on the carbon black used. Therefore, in the present invention, when carbon black is used, the type, amount, and combination of carbon black are changed, and the particle size, oil absorption, conductivity, pH, etc. are set within the above-mentioned range, depending on the purpose. Accordingly, it is preferable to change and use it.

The carbon black usable in the non-magnetic layer of the present invention can be referred to, for example, "Carbon Black Handbook" edited by Carbon Black Association.
In the present invention, the abrasive may be contained not only in the magnetic coating film but also in the non-magnetic layer. In the present invention, the magnetic coating film preferably contains carbon black having an average particle size of 50 to 300 mμ. If the average particle size of carbon black is less than 50 mμ, the friction coefficient tends to increase, while if the average particle size is more than 300 mμ, the surface properties are likely to deteriorate, electromagnetic conversion characteristics deteriorate, and spacing loss easily occurs. It is not preferable. As the carbon black contained in the magnetic coating film, furnace for rubber, thermal for rubber, black for color, acetylene black and the like can be used. The average primary particle size of carbon black is 50 to 300 mμ, preferably 70 to 280 mμ. Preferably, carbon black has a specific surface area of 5 to 500 m ² / g, DBP oil absorption of 10 to 400 ml / 100 g, pH of 2 to 10, water content of 0.1 to 10%, and tap density of 0.1 to 10%. To 1 g / cc. Carbon black which has been surface-treated with a dispersant or grafted with a resin or carbon black whose surface has been partially graphitized can also be used.

These carbon blacks may be previously dispersed with a binder before being added to the magnetic coating liquid. These carbon blacks can be used alone or in combination with other carbon blacks. When carbon black is used, it is preferably 0.1 to 30% of the amount based on the magnetic powder. In the present invention, the carbon black contained in the magnetic coating film is used for reducing the friction coefficient of the magnetic coating film, but carbon black having a function of imparting a light-shielding property and improving film strength can also be used in combination. In addition, carbon black having a smaller particle size than the above-mentioned particle size, depending on the purpose,
It is also possible to use together. For the carbon black that can be used in the magnetic coating film of the present invention, for example, "Carbon Black Handbook" edited by Carbon Black Association can be referred to. Examples of the binder used in the magnetic coating film and the non-magnetic layer of the present invention include conventionally known thermoplastic resins, thermosetting resins, reactive resins and mixtures thereof. The thermoplastic resin usable in the present invention has a glass transition temperature of −100 to 150 ° C. and a number average molecular weight of 1,000 to 200,000, preferably 10,000 to 1,000.
00, and a thermoplastic resin having a degree of polymerization of about 50 to 1000.

Examples of such thermoplastic resins include vinyl chloride, vinyl acetate, vinyl alcohol, maleic acid, acrylic acid, acrylic acid ester, vinylidene chloride, acrylonitrile, methacrylic acid, methacrylic acid ester, styrene and butadiene. Polymers or copolymers containing ethylene, vinyl butyral, vinyl acetal, vinyl ether, etc. as constituent units, polyurethane resins, and various rubber resins. Examples of the thermosetting resin or reactive resin include phenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, acrylic reaction resin, formaldehyde resin, silicone resin, epoxy resin. Examples thereof include a polyamide resin, a mixture of polyester resin and isocyanate prepolymer, a mixture of polyester polyol and polyisocyanate, and a mixture of polyurethane and polyisocyanate. These resins are described in detail in "Plastic Handbook" published by Asakura Shoten. It is also possible to use a known electron beam curable resin for the non-magnetic layer or the magnetic coating film. For these examples and the manufacturing method thereof, see JP-A-62-25621.
No. 9 discloses this in detail.

These resins can be used alone or in combination, but preferred are vinyl chloride resin, vinyl chloride vinyl acetate resin, vinyl chloride vinyl acetate vinyl alcohol resin, vinyl chloride vinyl acetate maleic anhydride. Examples thereof include a combination of at least one resin selected from the group consisting of copolymers and a polyurethane resin, or a combination of these with a polyisocyanate.
As the structure of the polyurethane resin, known materials such as polyester polyurethane, polyether polyurethane, polyether polyester polyurethane, polycarbonate polyurethane, polyester polycarbonate polyurethane, and polycaprolactone polyurethane can be used. For all of these binders, COOM, S
O ₃ M, OSO ₃ M, P = O, (OM) ₂ , OP = O
(OM) ₂ , (where M is a hydrogen atom or an alkali metal base), OH, NR ₂ , N ⁺ R ₃ (R is a hydrocarbon group) epoxy group, SH, CN, etc. It is preferable to introduce at least one or more polar groups selected from the following by copolymerization or addition reaction. The amount of such a polar group is from 10 ^-1 to 10 ^-8 mol / g, preferably from 10 ^-2 to 10 ^-6 mol / g.

Specific examples of these binders used in the present invention include VAG manufactured by Union Carbite Co., Ltd.
H, VYHH, VMCH, VAGF, VAGD, VRO
H, VYES, VYNC, VMCC, XYHL, XYS
G, PKHH, PKHJ, PKHC, PKFE, MPR-TA, MPR-TA5, MP manufactured by Nisshin Chemical Industry Co., Ltd.
R-TAL, MPR-TSN, MPR-TMF, MPR
-TS, MPR-TM, 100 manufactured by Denki Kagaku Kogyo Co., Ltd.
0W, DX80, DX81, DX82, DX83, Nippon Zeon Co., Ltd. MR110, MR100, 400X1
10A, Nippon Polyurethane Co., Ltd. Nipporan N23
01, N2302, N2304, Pandex T-5105, T-R308 manufactured by Dainippon Ink and Chemicals, Inc.
0, T-5201, Barnock D-400, D-210
-80, Crisbon 6109, 7209, Byron UR8200, UR8300, RV53 manufactured by Toyobo Co., Ltd.
0, RV280, UR8600, UR-5500, Dainichiseika Kogyo Co., Ltd. Daiferamine 4020, 502
0, 5100, 5300, 9020, 9022, 702
0, Mitsubishi Kasei Kogyo Co., Ltd. MX5004, Sanyo Kasei Kogyo Co., Ltd. Sampren SP-150, Asahi Kasei Kogyo Co., Ltd. Saran F310, F210 and the like.

The binder used in the magnetic coating film and the non-magnetic layer of the present invention is preferably 5 to 50 relative to the total amount of the magnetic powder contained in the magnetic coating film or the non-magnetic powder contained in the non-magnetic layer. It is used in the range of wt%, more preferably in the range of 10 to 30 wt%. When a vinyl chloride resin is used, the amount is 5 to 30% by weight, when a polyurethane resin is used, it is 2 to 20% by weight, and when a polyisocyanate is used, it is 2 to 20% by weight. It is preferable to use in combination. In the present invention, when a polyurethane resin is used as the binder, the glass transition temperature is -50 to 100 ° C,
Elongation at break 100 to 2000%, stress at break 0.0
5 to 10 kg / cm ² , yield point is 0.05 to 1
A polyurethane resin of 0 kg / cm ² is preferred. In the present invention, in the case of providing a non-magnetic layer, the amount of the binder, vinyl chloride resin in the binder, polyurethane resin,
The amount of polyisocyanate or other resin,
The molecular weight of each resin forming the magnetic coating film, the amount of polar groups, or the physical properties of the resin described above can be changed between the non-magnetic layer and the magnetic coating film, if necessary.

The polyisocyanate used in the present invention includes tolylene diisocyanate and 4-4'-.
Diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, naphthylene-1,5-diisocyanate, o-toluidine diisocyanate, isophorone diisocyanate, triphenyl Examples thereof include isocyanates such as methanetriisocyanate, products of these isocyanates with polyalcohols, and polyisocyanates produced by condensation of isocyanates. Specific examples of these isocyanates include Coronate L, Coronet HL, and Coronet manufactured by Nippon Polyurethane Co., Ltd.
2030, Coronate 2031, Millionate MR Millionate MTL, Takeda Pharmaceutical Co., Ltd. Takenate D-102, Takenate D-110N, Takenate D-
200, Takenet D-202, Sumitomo Bayer Co., Ltd. Desmodure L, Desmodule IL, Desmodule N Desmodule HL, etc., and these may be used alone or with different curing reactivity. By utilizing, two or more combinations can be used for both the magnetic coating film and the non-magnetic layer.

In the present invention, in order to improve running durability of the magnetic recording medium, it is preferable that the magnetic coating film or the non-magnetic layer contains a higher fatty acid. The higher fatty acid used for the magnetic coating film or the non-magnetic layer is mainly a monobasic fatty acid having 10 to 26 carbon atoms, which may be saturated or unsaturated, and may be linear or branched. The carbon to which the carboxyl group is bonded may be primary, secondary, or tertiary. Specific examples of these higher fatty acids include lauric acid, palmitic acid, myristic acid, stearic acid, behenic acid, oleic acid, linolenic acid, and elaidic acid. The amount of higher fatty acid added in the non-magnetic layer is
0.1% by weight to 2 with respect to the non-magnetic powder (when two or more non-magnetic powders are used, all of them)
It is 0% by weight, preferably 0.1% by weight to 10% by weight, and more preferably 0.1% by weight to 5% by weight. In the magnetic coating film, 0.1% by weight to 20% of the magnetic powder is used.
%, Preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight. Further, in the present invention, additives such as a dispersant, a lubricant, an antistatic agent, a surfactant and a plasticizer may be used depending on the purpose. As the additives, those having a lubricating effect, an antistatic effect, a dispersing effect, a plasticizing effect and the like are used. For example, molybdenum disulfide, tungsten disulfide graphite, boron nitride, graphite fluoride, silicone oil, silicone having a polar group, fatty acid-modified silicone
Fluorine-containing silicone, fluorine-containing alcohol, fluorine-containing ester, polyolefin, polyglycol,
Alkyl phosphates and alkali metal salts thereof, alkyl sulfates and alkali metal salts thereof, polyphenyl ether, fluorine-containing alkyl sulfates and alkali metal salts thereof, monovalent, divalent, trivalent, and tetravalent having 12 to 22 carbon atoms , Pentavalent or hexavalent alcohol (which may contain an unsaturated bond or may be branched), and has 12 carbon atoms.
To 22 alkoxy alcohols, 2 to 1 carbon atoms
Mono-fatty acid consisting of 2 monovalent, divalent, trivalent, tetravalent, pentavalent or hexavalent alcohol (which may contain an unsaturated bond or may be branched). Ester or di-fatty acid ester or tri-fatty acid ester, fatty acid ester of alkylene oxide polymer of monoalkyl ether, fatty acid amide having 8 to 22 carbon atoms, aliphatic amine having 8 to 22 carbon atoms, fatty acid and alcohol having 10 to 24 carbon atoms A fatty acid ester consisting of (containing an unsaturated bond or branched) may be used. Specific examples of these include stearic acid amide, myristic acid amide, butyl stearate, oleyl oleate, octyl stearate, amyl stearate,
Isooctyl stearate, octyl myristate, butoxyethyl stearate, anhydrosorbitan monostearate, anhydrosorbitan distearate,
Examples include anhydrosorbitan tristearate, oleyl alcohol, and lauryl alcohol. Further, nonionic surfactants such as alkylene oxide-based, glycerin-based, glycidyl-based, alkylphenol ethylene oxide adducts, cyclic amines, ester amides,
Cationic surfactants such as quaternary ammonium salts, hydantoin derivatives, heterocycles, phosphoniums or sulfoniums, and anionic surfactants containing acidic groups such as carboxylic acid, sulfonic acid, phosphoric acid, sulfuric acid ester group and phosphoric acid ester group Agents, amino acids, aminosulfonic acids, sulfuric acid or phosphoric acid esters of amino alcohol, and amphoteric surfactants such as alkylbedine type. These surfactants are described in detail in "Surfactant Handbook" (published by Sangyo Tosho Co., Ltd.). These dispersants, lubricants, antistatic agents, surfactants, additives such as plasticizers do not necessarily have to be 100% pure, and isomers, unreacted substances, side reactions other than the main component Impurities such as substances, decomposed products, and oxides may be included. The content of these impurity components is preferably 30% by weight or less, more preferably 10% by weight or less.

Additives such as these dispersants, lubricants, antistatic agents, surfactants and plasticizers used in the present invention are
The type and amount of the non-magnetic layer and the magnetic coating film can be properly used according to need. For example, in the non-magnetic layer and the magnetic coating, fatty acids having different melting points are used to control bleeding to the surface, or esters having different boiling points and polarities are used to control bleeding to the surface, It is conceivable that the stability of coating is improved by adjusting the amount of the surfactant, or the amount of the lubricant added is increased in the intermediate layer to improve the lubricating effect. For other purposes, additives such as a dispersant, a lubricant, an antistatic agent, a surfactant, and a plasticizer are added to the non-magnetic layer and the magnetic coating film according to the kind,
It goes without saying that the amount can be properly used in other modes. All or part of the additives used in the present invention may be added in any step of the magnetic coating solution manufacturing step. For example, before the kneading step, even if mixed with the magnetic powder, added in the kneading step of kneading the magnetic powder and the binder with a solvent, or added in the dispersing step,
It may be added after dispersion or just before coating. Specific examples of these lubricants used in the present invention include NAA-102, NAA-415 and NAA manufactured by NOF CORPORATION.
-312, NAA-160, NAA-180, NAA-
174, NAA-175, NAA-222, NAA-3
4, NAA-35, NAA-171, NAA-122,
NAA-142, NAA-160, NAA-173K,
Castor hardened fatty acid, NAA-42, NAA-44, cation SA, cation MA, cation AB, cation B
B, nymine L-201, nymine L-202, nymine S-202, nonion E-208, nonion P
-208, nonion S-207, nonion K-204,
Nonion NS-202, Nonion NS-210, Nonion HS-206, Nonion L-2, Nonion S-2, Nonion S-4, Nonion O-2, Nonion LP-20
R, nonion PP-40R, nonion SP-60R, nonion OP-80R, nonion OP-85R, nonion LT-221, nonion ST-221, nonion OT-
221, Monoguri MB, Nonion DS-60, Anon B
F, Anon LG, Butyl stearate, Butyl laureate
, Erucic acid, Kanto Chemical Co., Ltd. oleic acid, Takemoto Yushi Co., Ltd. FAL-205, FAL-123, Shin Nippon Rika Co., Ltd. Engerb LO, Enjorub IP
M, Sanso Sizer-E4030, TA-3, KF-96, KF-96L, KF96 manufactured by Shin-Etsu Chemical Co., Ltd.
H, KF410, KF420, KF965, KF54,
KF50, KF56, KF907, KF851, X-2
2-819, X-22-822, KF905, KF70
0, KF393, KF-857, KF-860, KF-
865, X-22-980, KF-101, KF-10
2, KF-103, X-22-3710, X-22-3
715, KF-910, KF-3935, Lion-
A-Mide P, A-Mide C, A-Moslip CP manufactured by Maru Co., Ltd., Duomin TD manufactured by Lion Oil & Fat Co., Ltd.
O, BA-41G manufactured by Nisshin Oil Co., Ltd., Profan 2012E manufactured by Sanyo Kasei Co., Ltd., Newport PE6
1, Ionette MS-400, Ionette MO-20
0, Ionette DL-200, Ionette DS-30
0, Ionet DS-1000 Ionet DO-200
And the like.

Examples of the organic solvent used in the present invention include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, isophorone and tetrahydrofuran, methanol,
Ethanol, propanol, butanol, isobutyl alcohol, isopropyl alcohol, alcohols such as methylcyclohexanol, methyl acetate, butyl acetate, isobutyl acetate, isopropyl acetate, ethyl lactate,
Esters such as glycol acetate, glycol dimethyl ether, glycol monoethyl ether, glycol ethers such as dioxane, aromatic hydrocarbons such as benzene, toluene, xylene, cresol, and chlorobenzene, methylene chloride, ethylene chloride, Chlorinated hydrocarbons such as carbon tetrachloride, chloroform, ethylene chlorohydrin and dichlorobenzene, N, N-dimethylformamide, hexane and the like can be used in any ratio. These organic solvents are not necessarily 10
It does not have to be 0% pure, and may contain impurity components such as isomers, unreacted products, by-products, decomposition products, oxides, and water in addition to the main component. The content of these impurity components is preferably 30% by weight or less, more preferably 10% by weight or less. The organic solvent used in the present invention is
If necessary, the type and amount of the magnetic coating film and the non-magnetic layer may be changed. For example, a solvent with high volatility is used for the magnetic coating film to improve the surface property, or a solvent with high surface tension such as cyclohexanone or dioxane is used for the non-magnetic layer to improve the stability of the coating, or the magnetic coating film. For example, a solvent having a high solubility parameter may be used to increase the filling degree, but the present invention is not limited to these examples.

In the magnetic recording medium according to the present invention, the thickness of the non-magnetic support is preferably 1 to 100 μm, more preferably 2 to 80 μm. The thickness of the nonmagnetic layer is preferably 0.1 μm to 10 μm, more preferably 0.5 to 5 μm. The thickness of the magnetic coating film is 0.05 μm or more and 4.0 μm or less, and preferably,
When the nonmagnetic layer is provided, the thickness is preferably 0.1 μm or more and 1.0 μm or less, and more preferably 0.1 μm or more and 0.8 μm or less. The total thickness of the magnetic coating film and the non-magnetic layer is preferably 1/100 to 2 times the thickness of the non-magnetic support. Further, an undercoat layer is preferably provided between the nonmagnetic support and the nonmagnetic layer in order to improve the adhesion between the nonmagnetic support and the nonmagnetic layer, and the thickness of the undercoat layer is 0.0
It is 1 to 2 μm, preferably 0.05 to 0.5 μm. Further, a back coat layer may be provided on the side of the non-magnetic support opposite to the side of the magnetic coating film. The backcoat layer has a thickness of 0.1 to 2 μm, preferably 0.3 to 1.0 μm. Known materials can be used as the undercoat layer and the back coat layer. The non-magnetic support used in the present invention includes polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins, cellulose triacetate, polycarbonate, polyamide, polyimide, polyamideimide, polysulfone. Well-known films of aramid, aromatic polyamide, etc. can be mentioned. These supports may be previously subjected to corona discharge treatment, plasma treatment, easy adhesion treatment, heat treatment, dust removal treatment, and the like. In order to achieve the object of the present invention, it is preferable to use a non-magnetic support having a center line average surface roughness of 0.001 to 0.03 μm, and more preferably 0.001 to 0.02.
μm, most preferably 0.001 to 0.01 μm. Further, it is preferable that these non-magnetic supports not only have a small center line average surface roughness but also do not have coarse protrusions of 1 μm or more. Where the surface roughness is
If necessary, it can be freely controlled depending on the size and amount of the filler added to the support. Examples of these fillers include oxides and carbonates such as Ca, Si and Ti, and organic fine powders such as acryl.

The heat shrinkage ratio of the non-magnetic support used in the present invention in the longitudinal running direction and the width direction at 100 ° C. for 30 minutes is preferably 3% or less, more preferably 1.5% or less, 80%. The heat shrinkage rate at 30 ° C. for 30 minutes is preferably 1% or less, more preferably 0.5% or less.
The breaking strength of the non-magnetic support is 5 to 10 in both directions.
0 Kg / mm ² , modulus of elasticity is 100 to 2000 Kg /
It is preferably mm ² . The step of producing the magnetic coating liquid for forming the magnetic coating film of the magnetic recording medium according to the present invention comprises at least a kneading step, a dispersing step and, before and after these steps, a mixing step carried out as necessary. There is. Each step may be performed in two or more stages. Magnetic powder used in the present invention, a binder,
All raw materials such as carbon black, abrasives, antistatic agents, lubricants and solvents can be added at the beginning or in the middle of any step. In addition, each raw material can be added in two or more steps. For example, polyurethane may be added separately in a kneading step, a dispersing step, and a mixing step for adjusting viscosity after dispersion. In the present invention, conventional known manufacturing techniques for manufacturing a magnetic recording medium can be used. As a kneading device, an open kneader, a continuous kneader, a pressure kneader, or the like is used. In kneading, the magnetic powder or the non-magnetic powder and all or a part of the binder (but not all) The binder is preferably 30% or more.) Is kneaded with a solvent in a range of 15 parts by weight to 500 parts by weight based on 100 parts by weight of the magnetic powder or the nonmagnetic powder. Details of these kneading treatments are described in JP-A-1-106338 and JP-A-64-79274.

In the present invention, examples of the method for providing a magnetic coating film on a non-magnetic support include gravure coating, roll coating, blade coating and extrusion coating methods which are generally used for coating a magnetic coating solution. To be In the present invention, when a non-magnetic layer and a magnetic coating film are provided on a non-magnetic support, gravure coating, roll coating, blade coating, extrusion coating equipment and the like generally used for coating a magnetic coating liquid are used. A non-magnetic layer is applied and dried, and then a support pressure type extrusion coating apparatus disclosed in JP-B-1-46186, JP-A-60-238179 and JP-A-2-265672. Using a method to form a magnetic coating film, gravure coating, roll coating, blade coating, extrusion coating equipment, etc., the nonmagnetic layer is coated, and while the nonmagnetic layer is in a wet state, Using a support pressure type extrusion coating device disclosed in JP-A-1-46186, JP-A-60-238179 and JP-A-2-265672, magnetic A method of forming a coating film, JP 63-
88080, JP-A-2-17971, JP-A-2-2
Japanese Patent Application Laid-Open No. 2-174965, a method for forming a non-magnetic layer and a magnetic coating film at substantially the same time by using a coating apparatus composed of a single coating head having two slits for coating liquid as disclosed in JP-A-2-174965. It is possible to use a method of forming the non-magnetic layer and the magnetic coating film almost at the same time by using the extrusion coating device with a backup roller disclosed in Japanese Patent Laid-Open Publication No. Among these methods, the method of coating the magnetic coating film on the non-magnetic layer while the non-magnetic layer is in a wet state is preferable, and the non-magnetic layer and the magnetic coating film are almost simultaneously coated on the non-magnetic support. Is more preferable.

The same applies to the case where two or more magnetic coating films are provided in the present invention. In the present invention, as the calendaring roll for orientation, epoxy, polyimide,
A heat-resistant plastic roll such as polyamide or polyimide amide can be used. In addition, calendar processing can be performed between metal rolls. The calendering temperature is preferably 70 to 150 ° C, more preferably 80 to 150 ° C. The linear pressure is
It is preferably 200 to 500 Kg / cm, more preferably 300 to 400 Kg / cm. The friction coefficient of the magnetic coating surface and the opposite surface of the magnetic recording medium according to the present invention with respect to SUS420J is preferably 0.5.
Or less, more preferably 0.3 or less, and the surface resistivity is
Preferably 10 ⁻⁵ to 10 ⁻¹² ohm / sq, the elastic modulus of the magnetic coating film at 0.5% elongation is preferably 100 to 2000 Kg / mm ^{2 in} both the running direction and the width direction, and the breaking strength is The elastic modulus of the magnetic recording medium is preferably 1 to 30 Kg / cm ² , the elastic modulus of the magnetic recording medium is preferably 100 to 1500 Kg / mm ^{2 in} both the running direction and the long direction, and the residual spread is
The heat shrinkage at any temperature of preferably 0.5% or less and 100 ° C. or less is preferably 1% or less, more preferably 0.5% or less, and most preferably 0.1% or less.

In the present invention, the elastic modulus of the magnetic coating film is preferably 100 to 2000 Kg / mm ² in both the longitudinal direction and the width direction, and the elastic modulus of the nonmagnetic layer is preferably in the longitudinal direction and the width direction. 100 to 200
It was 0 kg / mm ^2, the elastic modulus of the magnetic layer and the nonmagnetic layer depending on the purpose, may be different. In the present invention, the amount of residual solvent contained in the magnetic coating film and the non-magnetic layer is preferably 100 mg / m ² or less, more preferably 10 mg / m ² or less. In the present invention, the magnetic coating film and the porosity of the magnetic coating film are preferably 30% by volume.
Or less, more preferably 10% by volume or less. Regarding the magnetic characteristics of the magnetic recording medium according to the present invention, the squareness ratio in the orientation direction when measured with a magnetic field of 10 KOe is preferably 0.70 or more, and particularly preferably 0.80 or more.
In the present invention, when the magnetic recording medium includes two or more layers, that is, one non-magnetic layer and one magnetic coating film, one non-magnetic layer and two or more magnetic coating films, two or more non-magnetic layers. It goes without saying that when the magnetic layer and the one-layer magnetic coating film are included, and when the two or more non-magnetic layers and the two or more magnetic coating films are included, the physical characteristics of each layer can be changed. For example, the elastic modulus of the non-magnetic layer is increased to improve running durability, and at the same time, the elastic modulus of the magnetic coating is made lower than that of the non-magnetic coating to improve the contact of the magnetic recording medium with the head. And so on.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a schematic front view of a magnetic recording medium manufacturing apparatus according to a preferred embodiment of the present invention. In FIG. 1, a web-shaped non-magnetic support 1 is delivered from a delivery roll 2 and an extrusion-type simultaneous multi-layer coating apparatus 3 having two slits is provided on the surface thereof to form an upper layer containing magnetic powder at the same time. Magnetic coating liquid and lower non-magnetic coating liquid are applied, and the upper magnetic coating film 5 and the lower non-magnetic coating film 4 have a dry thickness of 0.2 μm and 1.5 μm, respectively.
m is formed. It goes without saying that the dry thickness of the upper magnetic coating 5 and the lower non-magnetic coating 4 can be selected according to the purpose. After that, a pre-orientation treatment device composed of a pair of permanent magnets 6 arranged so that the N poles are opposed to the upper magnetic coating film 5 and the lower non-magnetic coating film 4 is applied to the non-magnetic support 1. A magnetic field in the longitudinal direction is applied, and the magnetic powder in the upper magnetic coating film 5 is oriented in the longitudinal direction of the non-magnetic support 1.

The longitudinal orientation of the non-magnetic support 1 by this pre-orientation device is more than twice the coercive force of the magnetic powder,
Moreover, it is preferable to carry out under a magnetic field of 15000 oersteds or less, and more preferably, a non-magnetic support by a magnetic field of 3 times or more the coercive force of the magnetic powder and 10,000 oersteds or less, for example, 7500 oersteds. The body 1 is oriented in the longitudinal direction. The time for applying the magnetic field to the magnetic powder is preferably 3 milliseconds to 100 milliseconds, and 6 milliseconds to 1 millisecond.
More preferably, it is 00 milliseconds. Then, the upper magnetic coating film 5 and the lower non-magnetic coating film 4 in which the magnetic powder is oriented in the longitudinal direction of the non-magnetic support 1 are primarily dried by the preliminary drying device 7. The drying conditions by the preliminary drying device 7 are such that the total amount of the organic solvent contained in the upper layer magnetic coating liquid and the lower layer magnetic coating liquid is 100% by weight. It is preferable that the amount of the residual solvent at the outlet of the preliminary drying device 7 is set to 50 to 90% by weight.
It is more preferable to set the amount of the residual solvent in the upper magnetic coating film 5 and the lower non-magnetic coating film 4 at the outlet of 1 to 60 to 80% by weight.

The upper magnetic coating film 5 and the lower non-magnetic coating film 4 that have been primarily dried by the pre-drying device 7 are sent to an orientation treatment device composed of a solenoid coil 8. In the alignment treatment device, heated air is blown to dry the upper magnetic coating film 5 and the lower non-magnetic coating film 4, while the magnetic powder in the upper magnetic coating film 5 is transferred to the non-magnetic support 1.
The alignment treatment is performed again in the longitudinal direction of. Here, the tunnel width of the solenoid coil 8 is set to 1.15 times or more the width of the upper magnetic coating film 5. Further, the strength of the central portion of the magnetic field generated by the solenoid coil 8 is preferably 1 time or more the coercive force of the magnetic powder and 10000 oersted or less, more preferably 1.5 times the coercive force of the magnetic powder. Above, and below 8000 Oersted, for example, is set to 4500 Oersted. The magnetic powder in the upper magnetic coating film 5 is subjected to a longitudinal orientation treatment by the pair of permanent magnets 6 and 6,
The magnetic repulsive force of the magnetic powder itself may change the direction from the longitudinal direction. However, since the magnetic powder is oriented again in the longitudinal direction by the solenoid coil 8, all the magnetic powder is oriented in the longitudinal direction of the non-magnetic support 1.

After the orientation process by the solenoid coil 8 is thus performed, the upper magnetic coating film 5 and the lower non-magnetic coating film 4 are finally dried by the drying device 9 and further calendered by the calendering device 10. After the cutting, the slitter 11 cuts the magnetic recording medium.

[0032]

EXAMPLES In order to make the effects of the present invention clearer, examples will be given below. Example 1 A magnetic recording medium was manufactured by the following method using the magnetic recording medium manufacturing apparatus shown in FIG. Width 510mm,
An extrusion type simultaneous multi-layer coating apparatus 3 having two slits was provided on the surface of a long polyethylene terephthalate film having a thickness of 10 μm, and at the same time, the upper layer magnetic coating solution and the lower layer magnetic coating solution having the following compositions were simultaneously applied. The coating width is 500 mm, and the thickness after drying is 0.2 μm and 1.5 μm, respectively.
An upper magnetic coating and a lower non-magnetic coating were formed. Magnetic coating liquid for upper layer Fe / Zn / Ni (weight ratio 92: 4: 4) powder ...... 300 parts by weight (Needle-shaped particles with an average particle diameter of 0.10 μm in the major axis direction; / Short axis ratio = 5; Coercive force 2000 oersted) Vinyl chloride-vinyl acetate copolymer: 30 parts by weight (copolymerization ratio 87:13; degree of polymerization 400) conductivity Carbon black: 20 parts by weight Polyamide resin (amine value: 300): 15 parts by weight Lecithin: 6 parts by weight Silicone oil (dimethyl polysiloxane) 3 parts by weight Cyclohexane ...・ ・ ・ ・ ・ ・ ・ ・ ・ 300 parts by weight Methyl ethyl ketone 300 parts by weight of n- butanol ····················· 100 parts by weight of lower layer non-magnetic coating liquid TiO ₂ powder ........... 300 parts by weight (average primary particle size 0.05 μm; S _BET value 18 m ² / g) Vinyl chloride-vinyl acetate copolymer 30 parts by weight (copolymerization ratio 87:13; degree of polymerization 400) Conductive carbon black 20 parts by weight Polyamide resin (amine value 300) 15 parts by weight lecithin 6 parts by weight Silicone oil (dimethyl polysiloxane) 3 parts by weight cyclohexane 500 parts by weight n-butano 100 parts by weight The N pole faces the upper magnetic coating 5 and the lower non-magnetic coating 4 thus formed. A magnetic field having a strength of 7500 Oersted was applied by the pair of arranged permanent magnets 6, 6 to pre-orient the magnetic powder in the upper magnetic coating film in the longitudinal direction of the polyethylene terephthalate film.

Then, a preliminary drying device was used to remove about 3 parts of the solvent.
The upper magnetic coating film and the lower non-magnetic coating film are primarily dried by blowing heated air until 5% is evaporated, and the solenoid coil 8 having a tunnel width of 600 mm blows heated air to 4000 oersted. The magnetic powder in the upper magnetic coating film was oriented again in the longitudinal direction of the polyethylene terephthalate film by applying a magnetic field having a central strength of. Further, the upper magnetic coating film and the lower non-magnetic coating film are dried by a drying device 9, calendered by a calendering device 10, and then cut by a slitter 11 to obtain a magnetic recording medium sample # 1. It was Example 2 A magnetic recording medium sample # 2 was obtained in exactly the same manner as in Example 1 except that when the upper magnetic coating film was oriented by the solenoid coil 8, heated air was not blown. Example 3 A magnetic recording medium sample # 3 was obtained in exactly the same manner as in Example 1 except that the preliminary drying device 7 did not perform drying. Example 4 A magnetic recording medium sample # 4 was obtained in the same manner as in Example 2 except that the drying by the preliminary drying device 7 was not performed. Example 5 A magnetic recording medium sample # 5 was obtained in the same manner as in Example 3 except that the pre-orientation was not performed by the pair of permanent magnets 6, 6. Example 6 A magnetic recording medium sample # 6 was obtained in exactly the same manner as in Example 4 except that the pre-orientation by the pair of permanent magnets 6, 6 was not performed. Example 7 A magnetic recording medium sample # 7 was obtained in the same manner as in Example 1 except that the solenoid coil 8 having a tunnel width of 575 mm was used. Example 8 A magnetic recording medium sample # 8 was obtained in the same manner as in Example 2 except that the solenoid coil 8 having a tunnel width of 575 mm was used. Example 9 A magnetic recording medium sample # 9 was obtained in the same manner as in Example 3 except that the solenoid coil 8 having a tunnel width of 575 mm was used. Example 10 A magnetic recording medium sample # 10 was obtained in the same manner as in Example 4 except that the solenoid coil 8 having a tunnel width of 575 mm was used. Example 11 A magnetic recording medium sample # 11 was obtained in the same manner as in Example 5 except that the solenoid coil 8 having a tunnel width of 575 mm was used. Example 12 A magnetic recording medium sample # 12 was obtained in the same manner as in Example 6 except that the solenoid coil 8 having a tunnel width of 575 mm was used. Comparative Example 1 A magnetic recording medium sample # 13 was obtained in the same manner as in Example 1 except that the solenoid coil 8 having a tunnel width of 550 mm was used. Comparative Example 2 A magnetic recording medium sample # 14 was obtained in the same manner as in Example 2 except that the solenoid coil 8 having a tunnel width of 550 mm was used. Comparative Example 3 A magnetic recording medium sample # 15 was obtained in the same manner as in Example 3 except that the solenoid coil 8 having a tunnel width of 550 mm was used. Comparative Example 4 A magnetic recording medium sample # 16 was obtained in the same manner as in Example 4 except that the solenoid coil 8 having a tunnel width of 550 mm was used. Comparative Example 5 A magnetic recording medium sample # 17 was obtained in the same manner as in Example 5 except that the solenoid coil 8 having a tunnel width of 550 mm was used. Comparative Example 6 A magnetic recording medium sample # 18 was obtained in exactly the same manner as in Example 6 except that the solenoid coil 8 having a tunnel width of 550 mm was used.

The squareness ratio in the longitudinal direction of each of the obtained samples # 1 to 18 was measured with an applied magnetic field of 10 KOe using a vibrating sample magnetometer (VSM) manufactured by Toei Industry Co., Ltd.
2 to 4 are graphs showing the measurement results. FIG.
4 to 4, SQ represents the squareness ratio in the longitudinal direction of the sample, and the width direction position represents the distance measured from one side edge of the sample to the other side edge.
From FIG. 2, sample # 1 subjected to pre-orientation treatment, pre-drying and drying with heated air during the orientation treatment,
Sample # 7 and Sample # 13 both show a high squareness ratio in the longitudinal direction, but the sample # 1 according to the embodiment of the present invention using the solenoid coil 8 having a tunnel width of 600 mm is not No decrease in squareness was observed at the side edges of the magnetic support, and in the sample # 7 according to the example of the present invention using the solenoid coil 8 having a tunnel width of 575 mm, the non-magnetic support was used. It can be seen that the squareness is slightly reduced at the side edges of the solenoid coil 8 having a tunnel width of 550 mm, which is not a problem in practical use.
It was confirmed that in the sample # 13 according to the comparative example using No. 3, the squareness ratio was significantly reduced at the side edge portion of the non-magnetic support.

Further, from FIG. 2, sample # 2 and sample # 8 were subjected to the pre-orientation treatment and pre-drying, but not dried with heated air during the orientation treatment.
And Sample # 14 have relatively lower squareness ratios in the longitudinal direction as compared with Sample # 1, Sample # 7 and Sample # 13 dried by heated air during the alignment treatment, but relatively. It shows a high squareness ratio. However, Sample # 2 according to an embodiment of the present invention using a solenoid coil 8 having a tunnel width of 600 mm.
In the sample # 8 according to the example of the present invention using the solenoid coil 8 having a tunnel width of 575 mm, no decrease in the squareness ratio was observed even at the side edge of the non-magnetic support. It can be seen that the squareness ratio is slightly reduced at the side edges of the magnetic support, which is not a problem in practical use, whereas the solenoid coil 8 having a tunnel width of 550 mm was used. It was found that in Sample # 14 according to the comparative example, the squareness ratio was significantly reduced at the side edge portion of the non-magnetic support. From FIG. 3, the pre-orientation treatment and the drying with the heated air during the orientation treatment were performed, but the sample # 3, the sample # 9 and the sample # 15 which were not pre-dried were not subjected to the pre-orientation treatment and the pre-drying. But
Sample # 2, Sample # 8 and Sample # 14 that were not dried by heated air during the orientation process
Although slightly inferior, these samples show almost the same longitudinal squareness as these samples. But 600mm
In the sample # 3 according to the example of the present invention using the solenoid coil 8 having the tunnel width of, no decrease in the squareness ratio was observed even at the side edge portion of the non-magnetic support, and
Sample # 9 according to an embodiment of the invention using a solenoid coil 8 having a tunnel width of 575 mm has a slightly reduced squareness ratio at the side edges of the non-magnetic support, which is Although there is no problem in practical use, in the sample # 15 according to the comparative example using the solenoid coil 8 having a tunnel width of 550 mm, the squareness ratio is greatly reduced at the side edge of the non-magnetic support. Was approved.

Further, from FIG. 3, sample # 4 and sample # 1 which were subjected to the preliminary alignment treatment but were not dried with the heated air during the preliminary drying and the alignment treatment.
0 and sample # 16, samples # 1, # 2 and # 3, and sample # 7 which were subjected to preliminary drying and / or drying with heated air during the alignment processing in addition to the preliminary alignment processing. , # 8 and # 9 and samples # 13, # 14 and 15 have a lower squareness ratio in the longitudinal direction. However, a solenoid coil 8 with a tunnel width of 600 mm
In the sample # 4 according to the embodiment of the present invention, the decrease in the squareness ratio at the side edge of the non-magnetic support was not observed, and the present invention using the solenoid coil 8 having the tunnel width of 575 mm was used. # 10 according to the embodiment of
Then, it is recognized that the squareness ratio is slightly reduced at the side edge portion of the non-magnetic support, which is not a problem in practical use, whereas the solenoid coil 8 having a tunnel width of 550 mm is used. It was found that in the sample # 16 according to the comparative example using No. 3, the squareness ratio was significantly reduced at the side edge portion of the non-magnetic support. From FIG. 4, sample # which was dried with heated air during the alignment treatment but was not pre-aligned and pre-dried
5, Sample # 11 and Sample # 17 were all pre-aligned, but were not dried with heated air during the pre-drying and alignment processes Sample # 4, Sample # 10 and Sample # 1.
As compared with No. 6, the squareness ratio in the longitudinal direction is slightly higher.
However, a sample # according to an embodiment of the invention using a solenoid coil 8 having a tunnel width of 600 mm
In No. 5, no decrease in the squareness ratio at the side edge of the non-magnetic support was observed, and in Sample # 11 according to the example of the present invention using the solenoid coil 8 having a tunnel width of 575 mm, non-magnetic It can be seen that the squareness ratio is slightly reduced at the side edges of the support, which is not a problem in practical use, whereas a comparison using the solenoid coil 8 having a tunnel width of 550 mm is made. In the sample # 17 according to the example, it was found that the squareness ratio was significantly reduced at the side edge portion of the non-magnetic support.

Further, from FIG. 4, the pre-orientation treatment, the pre-drying treatment, and the pre-orientation treatment in the sample # 12 and the sample # 12 which were neither dried by the heated air during the orientation treatment, were performed.
The squareness ratio in the longitudinal direction is lower than that of the sample that was subjected to either preliminary drying or drying with heated air during the orientation treatment. However, in sample # 6 according to the example of the present invention using the solenoid coil 8 having a tunnel width of 600 mm, no decrease in the squareness ratio at the side edge of the non-magnetic support was observed, and 575 mm
In Sample # 12 according to the example of the present invention using the solenoid coil 8 having a tunnel width of, the squareness ratio is slightly reduced at the side edge of the non-magnetic support. Although there is no problem above, in the sample # 18 according to the comparative example using the solenoid coil 8 having the tunnel width of 550 mm, the squareness ratio is remarkably lowered at the side edge of the non-magnetic support. Was confirmed. Therefore, it is possible to orient the magnetic coating using a solenoid coil whose tunnel width is 1.15 times or more the width of the magnetic coating so that the magnetic field having a high squareness ratio in the longitudinal direction can be obtained over the entire width of the non-magnetic support. It has been found that it is indispensable for manufacturing a recording medium, and is more effective when a solenoid coil having a tunnel width 1.2 times or more the width of the magnetic coating film is used.

Further, it is preferable to perform at least one of pre-orientation treatment, pre-drying and drying with heated air during the orientation treatment in order to improve the squareness ratio in the longitudinal direction. Of these treatments, at least It is more preferable to perform two treatments, a pre-orientation treatment,
It has been found to be most preferable to carry out all the pre-drying and drying with heated air during the orientation treatment.
The present invention is not limited to the above embodiments and examples, and within the scope of the invention described in the claims,
It goes without saying that various modifications are possible and these are also included in the scope of the present invention. For example,
In the above-mentioned embodiment, the upper magnetic coating film 5 and the lower non-magnetic coating film 4 are formed at the same time, but it is not always necessary to form them at the same time, and two or more magnetic coating films may be formed simultaneously. It may be provided by coating or by successive multilayer coating. Further, it is not always necessary to provide a non-magnetic coating film.

[0039]

According to the present invention, it is possible to easily orient the magnetic powder in the magnetic coating film in the longitudinal direction of the non-magnetic support, even on both side edges of the non-magnetic support. It is possible to provide a method and an apparatus for manufacturing a magnetic recording medium capable of manufacturing a magnetic recording medium having an excellent squareness ratio in the longitudinal direction of the non-magnetic support over the entire width of the support.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a magnetic recording medium manufacturing apparatus according to a preferred embodiment of the present invention.

FIG. 2 is a graph showing the results of Examples and Comparative Examples.

FIG. 3 is a graph showing the results of Examples and Comparative Examples.

FIG. 4 is a graph showing the results of Examples and Comparative Examples.

[Explanation of symbols]

 1 non-magnetic support 2 delivery roll 3 simultaneous multi-layer coating device 4 lower non-magnetic coating film 5 upper magnetic coating film 6 permanent magnet 7 preliminary drying device 8 solenoid coil 9 drying device 10 calendering device 11 slitter

Claims (5)

[Claims] 1. A magnetic coating liquid is applied onto a long non-magnetic support which is continuously conveyed to form a magnetic coating film,
Orient the magnetic powder in the magnetic coating, dry the magnetic coating,
A method of manufacturing a magnetic recording medium for manufacturing a magnetic recording medium, wherein the width of the magnetic coating film on the non-magnetic support is 1.15.
With a solenoid coil that has more than double the tunnel width,
A method for producing a magnetic recording medium, which comprises generating an orientation magnetic field to orient the magnetic powder in the magnetic coating film. 2. The method of manufacturing a magnetic recording medium according to claim 1, wherein the magnetic powder in the magnetic coating film is oriented by the solenoid coil while drying the magnetic coating film. 3. The magnetic powder in the magnetic coating film is oriented by the solenoid coil after pre-orienting the magnetic powder in the magnetic coating film. Manufacturing method of magnetic recording medium of. 4. The magnetic powder in the magnetic coating film is pre-oriented, and after the magnetic coating film is pre-dried, the magnetic powder in the magnetic coating film is oriented by the solenoid coil. The method of manufacturing a magnetic recording medium according to claim 1, wherein 5. A coating device for forming a magnetic coating film by coating a magnetic coating liquid on a long non-magnetic support which is continuously conveyed, and a magnetic powder in the magnetic coating film is oriented. In an apparatus for manufacturing a magnetic recording medium, which comprises an orientation treatment device and a drying device for drying the magnetic coating film, the orientation treatment device has a width of 1.15 of the width of the magnetic coating film on the non-magnetic support.
An apparatus for manufacturing a magnetic recording medium, comprising a solenoid coil having a tunnel width equal to or more than twice the tunnel width.