JP2000090433A - Production of magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to execute good polishing by a smaller number of times of polishing than polishing of a magnetic layer surface of a magnetic recording medium by a polishing tape. SOLUTION: The tape-like or sheet-like magnetic recording medium 1 having a magnetic layer obtd. by coating the surface of a nonmagnetic base with a magnetic layer coating liquid contg. ferromagnetic powder and a binder, then drying the coating is brought into sliding contact with the polishing tape 2 having a polishing layer contg. polishing powder and a binder, by which the magnetic layer surface is subjected to a surface treatment. At this time, the polishing tape 2 and the magnetic recording medium 1 are brought into sliding contact with each other by non-paralleling the each other's sliding contact directions of both.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnetic recording medium in which the surface of a magnetic layer of a tape-shaped or sheet-shaped magnetic recording medium is treated with a polishing tape.

[0002]

2. Description of the Related Art A magnetic recording medium is prepared by applying a magnetic layer coating solution in which a ferromagnetic powder such as metal powder or iron oxide is dispersed in a binder called a binder on a non-magnetic support, and then dried and cured. After that, it is calendered and slit to a predetermined width to produce. In a process after the drying process, a surface treatment such as cleaning of the surface of the magnetic recording medium is performed. The surface treatment is performed by cleaning with a nonwoven fabric or tissue paper, or polishing with a polishing tape or the like containing an abrasive such as alumina oxide, chromium oxide, or silicon carbide.

For example, Japanese Patent Application Laid-Open No. 63-259830 discloses
There is disclosed a technique in which a magnetic layer of a magnetic recording medium is subjected to a surface smoothing treatment using a calender, and then the surface of the magnetic layer is polished with a polishing tape.

That is, the surface of the magnetic layer of the magnetic recording medium
Insufficiently fixed particulate components such as ferromagnetic powder are present, and the insufficiently fixed particulate components are detached during the running of the magnetic recording medium and adhere to the magnetic head, causing clogging and a decrease in output. . Further, there is also a problem that the surface roughness is increased due to insufficiently fixed granular components on the surface of the magnetic layer, causing wear of the surface of the magnetic head.

[0005] It is extremely difficult to perform surface treatment for removing particulate components insufficiently fixed on the surface of the magnetic layer in a short time. In blade treatment using a metal blade or a carbide blade, A plurality of treatments are required for an appropriate time, and the surface treatment by sliding the point polishing tape is effective.

[0006]

However, in polishing a magnetic recording medium with a polishing tape as described above, good surface treatment cannot be performed because the sliding directions are parallel to each other. Required and efficiency was low.

For example, the above-mentioned polishing tape is one in which a coating liquid containing a polishing powder and a binder is applied on a support to provide a polishing layer. When the above-mentioned coating liquid is applied by bar coating, In this case, bar streaks extending in the running direction are likely to occur on the polishing layer surface. When the polishing layer having the bar streak is brought into contact with the surface of the magnetic layer in parallel, irregularities corresponding to the irregularities of the polishing layer are left with a particle component that is not removed although it is necessary to remove the magnetic recording medium. The effect of suppressing wear and clogging of the magnetic head during use becomes insufficient, and surface treatment with a polishing tape is required a plurality of times.

In view of the foregoing, the present invention has been made in consideration of the above-mentioned problems, and provides a good surface treatment with a small number of polishing operations for polishing the surface of a magnetic layer of a magnetic recording medium with a polishing tape. An object of the present invention is to provide a method for manufacturing a magnetic recording medium capable of suppressing the occurrence of clogging.

[0009]

According to a method of manufacturing a magnetic recording medium of the present invention which solves the above-mentioned problems, a magnetic layer coating solution containing a ferromagnetic powder and a binder is coated on a non-magnetic support, and then dried. Then, the obtained tape-shaped or sheet-shaped magnetic recording medium having a magnetic layer is brought into sliding contact with a polishing tape having a polishing layer containing a polishing powder and a binder, and the surface treatment of the magnetic layer surface is performed. The tape and the magnetic recording medium are slid in non-parallel sliding directions.

It is desirable that the polishing layer of the polishing tape to be brought into sliding contact with the surface of the magnetic layer contains diamond in the polishing powder. In this case, it is preferable that diamond makes up 50% or more of the entire polishing powder.
The total thickness of the polishing tape containing diamond is 2
It is preferably from 100 μm to 100 μm.

On the other hand, the magnetic recording medium preferably has a thickness of the magnetic layer of 0.05 to 3.5 μm. Also,
It is preferable that the ferromagnetic powder of the magnetic layer comprises a metal powder.

The sliding contact between the magnetic recording medium and the polishing tape does not have to be completely parallel, and it is sufficient that the sliding contact is non-parallel with a slight angle. The sliding contact angle may be less than 90 °, preferably 2
The sliding contact is made at an angle of up to 70 °, for example, 5 °.

[0013]

According to the present invention as described above, the surface of the magnetic layer of the tape-shaped or sheet-shaped magnetic recording medium having the magnetic layer is brought into sliding contact with the polishing tape having the polishing layer containing the abrasive powder and the binder. When the surface treatment is performed, the polishing tape and the magnetic recording medium are brought into non-parallel sliding contact with each other, so that the surface treatment of the magnetic layer is efficiently performed and the magnetic layer surface is not required in a short time. It is possible to manufacture a tape-shaped or sheet-shaped magnetic recording medium with excellent characteristics, which can remove fine particulate components, cause less wear and clogging of the magnetic head, and have excellent characteristics.

When the polishing powder of the polishing tape contains, for example, 50% or more of diamond, the polishing power is high,
Particularly, good polishing can be performed with a small number of treatments.

In particular, the present invention is effective in a case where a polishing tape having a polishing layer applied by a bar coat application is used. Since the directions are non-parallel, the polishing tape moves and slides relatively in the width direction of the magnetic layer, and a granular component that is insufficiently removed due to the unevenness of the bar streaks remains on the surface of the magnetic layer after polishing. It can be removed without.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the method for manufacturing a magnetic recording medium according to the present invention will be described below, and the present invention will be described in further detail.

According to the method for producing a magnetic recording medium of the present invention, a magnetic layer coating solution containing a ferromagnetic metal powder and a binder is coated on a non-magnetic support, and then dried, and the obtained thickness is reduced to 0.05. ~
After slitting a tape-shaped or sheet-shaped magnetic recording medium having a magnetic layer of 3.5 μm to a predetermined width, the entirety having a polishing layer containing a binder and a polishing powder containing 50% or more of diamond and the like and a binder is contained. When the surface of the magnetic layer is surface-treated by being in sliding contact with a polishing tape having a thickness of 2 to 100 μm, the sliding contact between the polishing tape and the magnetic recording medium is made non-parallel so that they do not become parallel to each other and have an angle. It is to make sliding contact.

FIG. 1 shows the above-described polishing state, in which the tape-shaped or sheet-shaped magnetic recording medium 1 is run in the direction of arrow A, while the polishing tape 2 is run in the direction of arrow B opposite to the arrow A. A pad 3 is provided on the back side of the polishing tape 2, and the polishing layer surface of the polishing tape 2 is brought into contact with the magnetic layer surface of the magnetic recording medium 1, and the polishing is performed by sliding the two. At this time, the running direction A of the magnetic recording medium 1 and the running direction B of the magnetic tape 2 are not parallel to each other, but slide in a non-parallel state at a predetermined angle θ, and the angle θ is less than 90 °, preferably Is 2 ゜ to 70 ゜, for example 5
Set to ゜.

The magnetic recording medium comprises a nonmagnetic support and a magnetic layer in which ferromagnetic powder is dispersed in a binder as described above, while a polishing tape is provided on a flexible support. A polishing layer in which a polishing powder is dispersed in a binder, and both supports are formed of a material shown below, and the magnetic layer or the polishing layer is a binder made of the material shown below. In the magnetic layer, the following ferromagnetic powder is used, and in the polishing layer, the following polishing powder is mixed with other additives, and a magnetic coating liquid or a polishing layer coating liquid is applied on the support. And the basic manufacturing technology is the same.

The ferromagnetic powder used in the magnetic layer of the magnetic recording medium of the present invention is γ-FeOx (x = 1.33 to
1.5), Co-modified γ-FeOx (x = 1.33-1.
5) Main component of α-Fe or Ni or Co (75%
Known ferromagnetic powders such as ferromagnetic alloy powder, barium ferrite, and strontium ferrite described above can be used, but a ferromagnetic alloy powder containing α-Fe as a main component is preferable. In these ferromagnetic powders, A
1, Si, S, Sc, Ca, Ti, V, Cr, Cu,
Y, Mo, Rh, Pd, Ag, Sn, Sb, Te, B
a, Ta, W, Re, Au, Hg, Pb, Bi, La,
Ce, Pr, Nd, P, Co, Mn, Zn, Ni, S
It may contain atoms such as r, B, and Mg. In particular,
Al, Si, Ca, Y, Ba, L for metal magnetic material
a, Nd, Co, Ni, and B are important as elements contained in addition to α-Fe. In particular, Si, Al, and Y are important as surface treatments and sintering inhibitors. Preferably, Co is contained in an amount of 2 to 40% by weight based on Fe. Si, Al,
Y is contained between 0 and 10% by weight. These ferromagnetic powders may be treated in advance with a dispersant, a lubricant, a surfactant, an antistatic agent and the like described below before dispersion. Specifically, Japanese Patent Publication No. 44-14090 and Japanese Patent Publication No. 4
5-18372, JP-B-47-22062, JP-B-47-22513, JP-B-46-28466, JP-B-46-38755, JP-B-47-4286, JP-B-47-12422, and JP-B-47-22 -17284, JP-B-47-18509, JP-B-47-18573,
JP-B-39-10307, JP-B-48-39639
Nos., U.S. Pat.
No. 311904, No. 3242005, No. 3389
014 or the like.

Among the above ferromagnetic powders, the ferromagnetic alloy fine powder may contain a small amount of hydroxide or oxide. A ferromagnetic alloy fine powder obtained by a known production method can be used, and the following method can be used. 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, Thermal decomposition method, reduction method by adding a reducing agent such as sodium borohydride, hypophosphite or hydrazine to an aqueous solution of ferromagnetic metal, reduction of fine powder by evaporating metal in low-pressure inert gas And how to get it. The ferromagnetic alloy powder thus obtained is subjected to a known deoxidation treatment, that is, a method of immersing in an organic solvent and then drying, and immersing in an organic solvent and then feeding an oxygen-containing gas to form an oxide film on the surface and drying. Any of the methods of forming an oxide film on the surface by adjusting the partial pressure of oxygen gas and inert gas without using an organic solvent can be used.

When the ferromagnetic powder of the magnetic layer is expressed by a specific surface area by a BET method, it is 45 to 80 m ² / g, preferably 50 to 70 m ² / g. 40 m ² / g or less or 8
If it is 0 m ² / g or more, it is difficult to obtain surface properties, which is not preferable. The crystallite size of the ferromagnetic powder of the magnetic layer of the present invention is 300 to 1
00A, preferably 250-100A, more preferably 200-140A.

The saturation magnetization σs of the ferromagnetic powder is 100 to 18
0 emu / g is preferable, and 110-170 is more preferable.
emu / g, more preferably 125 to 160 emu / g.
The coercive force Hc of the ferromagnetic powder is preferably from 500 to 3000 Oe. The squareness ratio is preferably 0.6 to 0.98, and the magnetization amount of the magnetic layer is preferably 0.03 to 0.3 Gauss · cm. On the other hand, the needle ratio of the ferromagnetic powder is preferably from 4 to 18, and more preferably from 5 to 12. The water content of the ferromagnetic powder is 0.0
It is preferable to set it to 1 to 2%. It is preferable to optimize the water content of the ferromagnetic powder depending on the type of the binder.

It is preferable that the pH of the ferromagnetic powder is optimized by a combination with the binder used. The range is 4
-12, preferably 6-10. The ferromagnetic powder may be subjected to a surface treatment with Al, Si, P or an oxide thereof, if necessary. The amount thereof is 0.1 to 10% based on the ferromagnetic powder, and the surface treatment is preferable because the adsorption of a lubricant such as a fatty acid becomes 100 mg / m ² or less. Soluble Na, Ca, Fe, N
It may contain inorganic ions such as i and Sr. It is preferable that these are essentially absent, but if they are 200 ppm or less, they do not particularly affect the characteristics. Further, the ferromagnetic powder preferably has a small number of vacancies, and its value is preferably 20% by volume or less, more preferably 5% by volume or less.

The polishing powder used in the polishing layer of the polishing tape of the present invention is such that diamond accounts for 50% by weight or more of the constituent polishing powder, and the rest is generally a material having a polishing or polishing action. α-alumina, γ-alumina, α, γ-alumina, fused alumina, silicon carbide, chromium oxide, cerium oxide, corundum, α-iron oxide, garnet, emery (main components: corundum and magnetite), garnet, silica stone, Silicon nitride, boron nitride, molybdenum carbide,
Materials having a Moh's hardness of 6 or more, such as boron carbide, tungsten carbide, titanium carbide, tripoly, diatomaceous earth, and dolomite, can be used in combinations of 1 to 4 types. These abrasive powders have an average particle size of 0.005 to
Those having a size of 100 μm are used, and particularly preferably 0.01 to 50 μm. These polishing powders, in the case of a polishing layer, a binder 0.1 to 100 parts by weight of the polishing powder.
Used in the range of 50 parts by weight.

The diamond is an artificial diamond,
Classified products such as natural diamond can be used. These diamond crystals may be either single crystals or polycrystals. Alternatively, diamond formed by CVD (chemical vapor deposition) may be used. The surface of the diamond may be coated with a metal alloy or an organic resin.

Specific examples of other abrasive powders include:
AKP1, AKP15, AKP20, A manufactured by Sumitomo Chemical
KP30, AKP50, AKP80, Hit50, Hi
t100 and the like. About these
No. 28462, JP-B-49-39402, JP-A-6
3-98828, U.S. Pat. No. 3,687,725, U.S. Pat. No. 3,077,807, U.S. Pat. No. 3,041,196, U.S. Pat. No. 3,293,066, U.S. Pat. No. 3,630,910, U.S. Pat.
It is described in British Patent 1145349, West German Patent 853211 and the like.

Examples of the binder used in the magnetic layer of the magnetic recording medium of the present invention or the polishing layer of the polishing tape include conventionally known thermoplastic resins, thermosetting resins, reactive resins, electron beam curing resins, and ultraviolet rays. Curable resins, visible light curable resins, and mixtures thereof are used.

As the thermoplastic resin, the softening temperature is 150
C. or lower, having an average molecular weight of 10,000 to 300,000 and a degree of polymerization of about 50 to 2,000, more preferably 20 to 2,000.
It is about 0 to 600. For example, vinyl chloride vinyl acetate copolymer, vinyl chloride copolymer, vinyl chloride vinyl acetate vinyl alcohol copolymer, vinyl chloride vinyl alcohol copolymer, vinyl chloride vinylidene copolymer, vinyl acrylonitrile copolymer, acrylic acid Ester acrylonitrile copolymer, acrylate vinylidene chloride copolymer, acrylate styrene copolymer, methacrylate acrylonitrile copolymer,
Methacrylic acid ester vinylidene chloride copolymer, methacrylic acid ester styrene copolymer, urethane elastomer, nylon-silicone resin, nitrocellulose-polyamide resin, polyfucca vinyl, vinylidene chloride acrylonitrile copolymer, butadiene acrylonitrile copolymer, polyamide Resins, polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, ethyl cellulose, methyl cellulose, propyl cellulose, methyl ethyl cellulose, carboxymethyl cellulose,
Acetylcellulose), styrene-butadiene copolymer, polyester resin, polycarbonate resin, chlorovinyl ether acrylate copolymer, amino resin, various synthetic rubber-based thermoplastic resins, and mixtures thereof.

Examples of these resins are described in JP-B-37-68.
No. 77, JP-B-39-12528, JP-B-39-19
No. 282, No. 40-5349, No. 40-20
No. 907, JP-B-41-9463, JP-B-41-14
No. 059, JP-B-41-16985, JP-B-42-6
No. 428, JP-B-42-11621, JP-B-43-4
No. 623, JP-B-43-15206, JP-B-44-2
No. 889, No. 44-17947, No. 44-1
No. 8232, No. 45-14020, No. 45-
14500, JP-B-47-18573, JP-B-47
-22063, JP-B-47-2264, JP-B-4
7-22068, JP-B-47-22069, JP-B-47-22070, JP-B-47-27886, JP-A-57-133521, JP-A-58-137133.
JP-A-58-166533, JP-A-58-222
No. 433, JP-A-59-58642 and the like.
No. 71364, U.S. Pat. No. 4,752,530, and the like.

The thermosetting resin or the reactive resin has a molecular weight of 200,000 or less in the state of a coating liquid, and becomes infinite by a reaction such as condensation and addition by heating and humidifying after coating and drying. Is preferred. Among these resins, those which do not soften or melt before the resin is thermally decomposed are preferable. Specifically, for example, a phenol resin, a phenoxy resin, an epoxy resin, a polyurethane resin, a polyester resin, a polyurethane polycarbonate resin, a urea resin, a melamine resin, an alkyd resin, a silicone resin, an acrylic reaction resin (an electron beam curing resin), and an epoxy-polyamide Resin, nitrocellulose melamine resin, mixture of high molecular weight polyester resin and isocyanate prepolymer, mixture of methacrylate copolymer and diisocyanate prepolymer, mixture of polyester polyol and polyisocyanate, urea formaldehyde resin, low molecular weight glycol / high molecular weight A diol / triphenylmethane triisocyanate mixture, a polyamine resin, a polyimine resin, and mixtures thereof.

Examples of these resins are described in JP-B-39-810.
No. 3, JP-B-40-9779, JP-B-41-7192
No., JP-B-41-8016, JP-B-41-14275
No., JP-B-42-18179, JP-B-43-1208
No. 1, Japanese Patent Publication No. 44-28023, Japanese Patent Publication No. 45-145
No. 01, JP-B-45-24902, JP-B-46-13
103, JP-B-47-2265, JP-B-47-2
No. 2066, JP-B-47-22067, JP-B-47-
22072, JP-B-47-22073, JP-B-47
-28045, JP-B-47-28048, JP-B-4
It is described in publications such as 7-28922.

These thermoplastic resins, thermosetting resins and reactive resins have carboxylic acid (COOM), sulfinic acid, sulfenic acid, sulfonic acid (SO ₃ M), phosphoric acid (PO) as functional groups other than the main functional groups. (OM) (OM)), phosphonic acid, sulfuric acid (OSO ₃ M), and acidic groups such as ester groups thereof (M is H, an alkali metal, an alkaline earth metal,
Hydrocarbon groups), amino acids; aminosulfonic acids, sulfuric acid or phosphoric acid esters of amino alcohols, amphoteric groups such as alkyl betaine, amino groups, imino groups, imide groups,
An amide group, etc., a hydroxyl group, an alkoxyl group, a thiol group, an alkylthio group, a halogen group (F, Cl, Br,
I) a silyl group, a siloxane group, an epoxy group, an isocyanato group, a cyano group, a nitrile group, an oxo group, an acryl group, and a phosphine group. ^-6 eq ~ 1 × 10 ^-2
It is preferable to include eq.

[0034] These binders may be used alone or in combination, and other additives may be added. Examples of the additives include a dispersant, a lubricant, an abrasive powder, an antistatic agent, an antioxidant, and a solvent.

As the polyisocyanate used in the magnetic layer or the polishing layer of the present invention, tolylene diisocyanate, 4
-Isocyanates such as 4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, naphthylene-1.5-diisocyanate, o-toluidine diisocyanate, isophorone diisocyanate, triphenylmethane triisocyanate, isophorone diisocyanate, and the isocyanates and polyalcohols And polyisocyanates of 2 to 10 mer produced by condensation of isocyanates, and products of polyisocyanates and polyurethanes whose terminal functional groups are isocyanates. The average molecular weight of these polyisocyanates is preferably 100 to 20,000.

Commercially available trade names of these polyisocyanates include Coronate L, Coronate HL, Coronate 2030, Coronate 2031, Millionate MR, Millionate MTL (all manufactured by Nippon Polyurethane Co., Ltd.), Takenate D-102, and Takenate D-110.
N, Takenate D-200, Takenate D-202, Takenate 300S, Takenate 500 (manufactured by Takeda Pharmaceutical Co., Ltd.), Sumidur T-80, Sumidur 44S, Sumidur PF, Sumidur L, Sumidur N, Desmodur L , Death module IL, death module N, death module HL, death module T65, death module 15, death module R, death module R
F, death module SL, death module Z4273
(Manufactured by Sumitomo Bayer Co., Ltd.), and these can be used alone or in combination of two or more by utilizing the difference in curing reactivity.

For the purpose of accelerating the curing reaction, a hydroxyl group (butanediol, hexanediol, having a molecular weight of 100
A compound having an amino group (such as monomethylamine, dimethylamine, or trimethylamine), a metal oxide catalyst, or a catalyst such as iron acetylacetonate can also be used in combination. It is desirable that these compounds having a hydroxyl group or an amino group are polyfunctional. These polyisocyanates are preferably used in the magnetic layer, the polishing layer and the back layer in an amount of 2 to 70 parts by weight, more preferably 5 to 50 parts by weight, per 100 parts by weight of the total amount of the binder resin and the polyisocyanate. Examples of these are disclosed in JP-A-60-131622 and JP-A-61-61622.
No. 74138 and the like.

The powdery lubricant used for the magnetic layer or the polishing layer of the present invention includes graphite, molybdenum disulfide, boron nitride, graphite fluoride, calcium carbonate, barium sulfate, silicon oxide, titanium oxide, zinc oxide, and the like. Inorganic fine powders such as tin oxide and tungsten disulfide, acrylic styrene resin fine powder, benzoguanamine resin fine powder, melamine resin fine powder, polyolefin resin fine powder, polyester resin fine powder, polyamide resin fine powder, polyimide Resin fine powders such as fine resin powder and polyhooker ethylene resin fine powder.

Silicone oils (dialkyl polysiloxanes, dialkoxy polysiloxanes, phenyl polysiloxanes, fluoroalkyl polysiloxanes (KF96, KF69 manufactured by Shin-Etsu Chemical Co., Ltd.) can be used as organic compound-based lubricants.
)), Fatty acid-modified silicone oil, fluoroalcohol, polyolefin (polyethylene wax, polypropylene, etc.), polyglycol (ethylene glycol, polyethylene oxide wax, etc.), tetrafluoroethylene oxide wax, polytetrafluoroglycol, perfluoroalkyl ether, perfluoro Fatty acids, perfluoro fatty acid esters, perfluoroalkyl sulfates, perfluoroalkyl sulfonates, perfluoroalkylbenzene sulfonates, perfluoroalkyl phosphates, and other compounds containing fluorine or silicon, alkyl sulfates, alkyl sulfonates , Alkyl phosphonic acid triester,
Organic acids and organic acid ester compounds such as alkyl phosphonic acid monoesters, alkyl phosphonic acid diesters, alkyl phosphates, succinates, etc., triazaindolizine, tetraazaindene, benzotriazole, benzotriazine, benzodiazole, EDTA, etc. nitrogen·
Heterocyclic compound containing sulfur, having 10 to 40 carbon atoms
Consisting of a monobasic fatty acid of formula (I) and any one or more of monohydric or dihydric alcohols having 2 to 40 carbon atoms, trihydric alcohol, tetrahydric alcohol, and hexahydric alcohol Esters, fatty acid esters of monohydric to hexavalent alcohols having a total of 11 to 70 carbon atoms in total with monobasic fatty acids having 10 or more carbon atoms and carbon atoms of the fatty acids, 8 to 40 carbon atoms And fatty acid amides, fatty acid alkyl amides and aliphatic alcohols.

Specific examples of these compounds include butyl caprylate, octyl caprylate, ethyl laurate, butyl laurate, octyl laurate, ethyl myristate, butyl myristate, octyl myristate, 2-ethylhexyl myristate, Ethyl palmitate, butyl palmitate, octyl palmitate, 2 ethylhexyl palmitate, ethyl stearate, butyl stearate, isobutyl stearate, octyl stearate, 2 ethyl hexyl stearate, amyl stearate, isoamyl stearate, 2 stearic acid
Ethylpentyl, 2-hexyldecyl stearate, isotridecyl stearate, stearic acid amide, alkyl stearate, butoxyethyl stearate,
Anhydrosorbitan monostearate, anhydrosorbitan distearate, anhydrosorbitan tristearate, anhydrosorbitan tetrastearate, oleyl oleate, oleyl alcohol, lauryl alcohol, montan wax, carnauba wax, etc. used alone or in combination it can.

The lubricant used in the present invention includes:
Lubricating oil additives can be used alone or in combination. Antioxidants known as rust inhibitors (metal chelates such as alkylphenol, benzotriazine, tetraazaindene, sulfamide, guanidine, nucleic acid, pyridine, amine, hydroquinone, EDTA, etc.) Agents), rust inhibitors (naphthenic acid, alkenyl succinic acid, phosphoric acid, dilauryl phosphate, etc.), oil agents (rapeseed oil, lauryl alcohol, etc.), extreme pressure agents (dibenzyl sulfide, tricresyl phosphate, tributyl) Phosphite, etc.), detergents / dispersants, viscosity index improvers, pour point depressants, foaming agents and the like. These lubricants are used in an amount of 0.1 to 100 parts by weight of the binder.
It is added in the range of 01 to 30 parts by weight. These are described in JP-B-43-23889 and JP-B-48-2404.
No. 1, JP-B-48-18482, JP-B-44-182
21, JP-B-47-28043, JP-B-57-561
32, JP-A-59-8136, JP-A-59-8139
No. JP-A-61-85621, U.S. Pat.
No. 3, US Pat.
No. 35, U.S. Pat. No. 3,497,411, U.S. Pat.
No. 086, US Pat. No. 3,625,760, US Pat.
No. 0772, US Pat. No. 3,634,253, US Pat.
No. 42539, US Pat. No. 3,687,725, US Pat.
135031, U.S. Pat. No. 4,497,864, U.S. Pat. No. 4,552,794, IBM Technical Disclosure Britain (IBM Technical Di)
sclosure Bulletin) Vol. 9, N
o7, p779 (December 1966), ELEKTRONIK 1961 No12, p38
0, Chemical Handbook, Applied Edition, p 954-967, published in 1980 by Maruzen Stock.

The dispersing agent and dispersing agent for the ferromagnetic powder or abrasive powder used in the present invention include caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid and linoleic acid. Acid, linolenic acid, stearolic acid, behenic acid, maleic acid, phthalic acid and other fatty acids having 2 to 40 carbon atoms (R ₁ COOH, R ₁
Is an alkyl group having 1 to 39 carbon atoms, a phenyl group, an aralkyl group), and the alkali metal (Li, Na,
K, NH ₄ ^+, etc.) or alkaline earth metals (Mg, Ca, B)
a), metal soaps (copper oleate) made of Cu, Pb, etc., fatty acid amides; lecithin (soybean oil lecithin) and the like are used. In addition, higher alcohols having 4 to 40 carbon atoms (butanol, octyl alcohol, myristyl alcohol, stearyl alcohol) and their sulfates, sulfonic acids, phenylsulfonic acids, alkylsulfonic acids, sulfonic esters, phosphoric monoesters, phosphoric diesters , Phosphoric acid triesters, alkylphosphonic acids, phenylphosphonic acids, amine compounds and the like can also be used.
Further, polyethylene glycol, polyethylene oxide, sulfosuccinic acid, metal sulfosuccinate, sulfosuccinate, and the like can also be used. One or more of these dispersants are usually used, and one kind of the dispersant is added in an amount of 0.005 to 20 parts by weight based on 100 parts by weight of the binder. Regarding the method of using these dispersants, the dispersants may be preliminarily applied to the surface of the ferromagnetic powder, the polished powder, or the non-polished fine powder, or may be added during dispersion. Such materials are disclosed, for example, in JP-B-39-28369 and JP-B-44-17945.
No., JP-B-44-18221, JP-B-48-7441
No., JP-B-48-15001, JP-B-48-1500
No. 2, JP-B-48-16363, JP-B-49-394
No. 02, U.S. Pat.
No. etc.

As the antifungal agent used in the present invention, 2- (4
-Thiazolyl) -benzimidazole, N- (fluorodichloromethylthio) -phthalimide, 10.10'-
Oxybisphenoxalcin, 2,4,5.6 tetrachloroisophthalonitrile, P-tolyldiiodomethylsulfone, triiodoallyl alcohol, dihydroacetoacid, mercury phenyloleate, bis (tributyltin) oxide, saltylani There are rides. Such a substance is described in, for example, "Microbial Disaster and Prevention Technology", Engineering Book, 1972, "Chemistry and Industry", 32, 904 (1979).

As the antistatic agent used in the present invention, carbon black can be used.
Thermal for rubber, black for color, acetylene black and the like can be used. Its specific surface area is 5-500
m ² / g, DBP oil absorption 10-400 ml / 100
g, pH 2-10, water content 0.1-10%, tap density 0.1-1 g / cm ² . As a specific example of this carbon black, BLACKPEARLS 2000, 1300, 1 manufactured by Cabot Corporation
000,900,800,700, manufactured by Mitsubishi Chemical Corporation:
650B, 950B, 3250B, 850, 900, 9
60,980,1000,2300,2400,260
0 and the like. In addition, carbon black that has been subjected to surface treatment with a dispersant or the like or graphitized with a resin can also be used.

As the antistatic agent other than carbon black used in the present invention, graphite, modified graphite,
Conductive powders such as carbon black graft polymer, tin oxide-antimony oxide, tin oxide, titanium oxide-tin oxide-antimony oxide; natural surfactants such as saponin; alkylene oxide-based, glycerin-based, glycidol-based, polyhydric alcohol, Nonionic surfactants such as polyhydric alcohol esters and alkylphenol EO adducts; higher alkylamines, cyclic amines, hydantoin derivatives, amidoamines, esteramides, quaternary ammonium salts, pyridine and other heterocycles, phosphoniums and sulfoniums Anionic surfactants containing acidic groups such as carboxylic acid, sulfonic acid, phosphonic acid, phosphoric acid, sulfate ester group, phosphonate ester, phosphate ester group; amino acids; aminosulfonic acids, sulfuric acid of amino alcohol or Phosphoric esters, amphoteric surfactants such as alkyl betaine type and the like are used.

Some of the examples of the surfactant compound which can be used as the antistatic agent are described in JP-A-60-28025, US Pat. Nos. 2,271,623, 2,224,472, and 22.
88226, 2676122, 2676924
Nos. 2,676,975, 2,691,566,27
27860, 2730498, 2742379
Nos. 2739891, 3068101, 31
No. 58484, No. 3201253, No. 32010191
Nos. 3,294,540, 3,415,649 and 34
No. 41413, No. 3444254, No. 3475174
No. 3,545,974, West German Patent Publication (OLS) 19
No. 42665, British Patent Nos. 1077317 and 1198
No. 450, Ryohei Oda et al., "Synthesis of Surfactants and Their Applications" (Maki Shoten, 1972 edition); W. "Surfes Active Age Entities" by Beili (Interscience Publication Corporation 1
985); P. Encyclopedia of Surfactive Agents, Vol. 2 (Chemical publishing company, 1964 edition) by Sisley; Surfactant Handbook, 6th printing (Sangyo Tosho Co., Ltd.,
December 20, 1966); Hideo Marumo, "Antistatic Agent"
Koshobo (1968) and the like.

These surfactants may be added alone or as a mixture. These surfactants are used in an amount of 0.01 to 10 parts by weight per 100 parts by weight of the ferromagnetic powder or the abrasive powder. The amount used in the back layer is 0.01 to 30 parts by weight per 100 parts by weight of the binder. These are used as antistatic agents, but are sometimes applied for other purposes such as improvement of dispersion, improvement of lubricity, coating aid, wetting agent, curing accelerator, and dispersion accelerator. .

As the organic solvent used in the dispersion, kneading and coating of the present invention, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone and tetrahydrofuran in any ratio; methanol, ethanol, propanol and butanol , Isobutyl alcohol, isopropyl alcohol, alcohols such as methylcyclohexanol; methyl acetate,
Ester systems such as ethyl acetate, butyl acetate, isobutyl acetate, isopropyl acetate, ethyl lactate and glycol monoethyl ether; ether systems such as diethyl ether, tetrahydrofuran, glycol dimethyl ether, glycol monoethyl ether and dioxane; benzene, toluene, xylene, Tar-based (aromatic hydrocarbons) such as cresol, chlorobenzene, and styrene; chlorinated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, and dichlorobenzene; NN-dimethylformaldehyde , Hexane and the like can be used. These solvents are generally used in two or more kinds at an arbitrary ratio. Further, a trace amount of impurities (polymer of the solvent itself, moisture, raw material components, etc.) may be contained in an amount of 1% by weight or less. An aqueous solvent (water, alcohol, acetone, etc.) can be used instead of the organic solvent.

These solvents are used in an amount of 50 to 20,000 parts by weight based on 100 parts by weight of the total solid content of the magnetic paint or the abrasive paint. A preferred magnetic paint or abrasive paint has a solid content of 5 to 60% by weight.

The formation of the magnetic layer or the polishing layer is performed by dissolving in a solvent any combination of the above-mentioned compositions and the like, and coating and drying the coating solution on a support. The non-magnetic support for the magnetic recording medium or the support for the polishing tape is flexible and has a thickness of 2.
About 300 μm. Polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, vinyl resins such as polyvinyl chloride,
In addition to plastics such as polycarbonate, polyimide, polyamide, polyaramid, and polysulfone, metals such as aluminum and copper, and ceramics such as glass can also be used. Prior to coating, these supports may be subjected to corona discharge treatment, plasma treatment, undercoating treatment, heat treatment, dust removal treatment, metal deposition treatment, and alkali treatment. These supports are described in, for example, West German Patent 3,338,854A, JP-A-59-116926, and JP-A-61-129731.
No. 4,388,368; Yukio Mitsuishi, Textile and Industry, vol. 31, p. 50-55, 1975. The center line average surface roughness Ra of these supports is 0.
001 to 5.0 μm is preferred. The Young's modulus (F5 value) of these supports can be selected from ^{2 to} 30 kg / mm ² (1 kg / m ² = 9.8 Pa) in both the width direction and the longitudinal direction according to the purpose.

The method of dispersion and kneading is not particularly limited, and the order of addition of each component (resin, powder, lubricant, solvent, etc.)
The addition position during dispersion / kneading, the dispersion temperature (0 to 80 ° C.) and the like can be appropriately set. For preparing a magnetic paint or an abrasive paint, a usual kneading machine, for example, a two-roll mill, a three-roll mill, a ball mill, a pebble mill, a tron mill, a sand grinder, a Seggari attritor, a high-speed impeller, a disperser, a high-speed stone mill, Use high speed impact mill, disperser, kneader, high speed mixer, ribbon blender, co-kneader, intensive mixer, tumbler, blender, disperser, homogenizer, single screw extruder, twin screw extruder, ultrasonic disperser, etc. Can be. Usually, a plurality of these dispersing and kneading machines are provided for dispersing and kneading, and the treatment is continuously performed. For details of the technique relating to kneading and dispersion, see T.A. C. "Paint Flow and Pigment," by Patton (TC Patton)
Dispersion "(Paint Flow and Pigment Dispersion), 1964 John
Wiley & Sons, Inc. (John Wiley and Sons), Shinichi Tanaka, Industrial Materials, Vol. 25, 37 (1977), and other references cited in the book. In order to efficiently promote dispersion and kneading as an auxiliary material for these dispersion and kneading, a sphere equivalent diameter of 10 cmφ to 0.0
Steel balls, steel beads, ceramic beads, glass beads, and organic polymer beads having a diameter of 5 mmφ can be used. These materials are not limited to spherical shapes.
Also, U.S. Pat. Nos. 2,581,414 and 28551
It is also described in the specification such as No. 56. Also in the present invention, a magnetic paint or a polishing paint can be prepared by kneading and dispersing according to the method described in the above-mentioned book or the literature cited therein.

As a method for applying the above-mentioned magnetic paint or abrasive paint on the support, the viscosity of the coating solution is from 1 to 20,000.
Adjust to centistokes (25 ° C), air doctor coater, blade coater, air knife coater, squeeze coater, impregnation coater, reverse roll coater, transfer roll coater, gravure coater, kiss coater, cast coater, spray coater, rod coater, positive rotation A roll coater, a curtain coater, an extrusion coater, a bar coater, a lip coater, and the like can be used, and other methods are also available. The specific description of these methods is described in “Coating Engineering” 253 published by Asakura Shoten.
Pages 277 to 277 (issued by Showa 46.3.20). The order of application of these coating liquids can be arbitrarily selected, and a corona discharge treatment or the like may be performed before the application of the desired liquid to improve the adhesion to the undercoat layer or the support. The multilayer structure of the magnetic layer or the polishing layer may be a simultaneous multilayer coating, a sequential multilayer coating, or the like. These are described, for example, in JP-A-57-123532 and JP-B-62-3.
No. 7451, JP-A-59-142741 and JP-A-59-165239.

By such a method, about 1 to about
After the magnetic paint or the abrasive paint applied at about 200 μm is immediately subjected to a drying treatment in multiple stages at 20 to 130 ° C. as necessary, the formed magnetic layer is formed to a thickness of 0.05 to 3.5 μm, or Dry to a thickness of 0.05-10 μm. At this time, the transfer speed of the support is usually 10 m / min.
The drying is performed at 900 m / min, the drying temperature is controlled at 20 ° C. to 130 ° C. in a plurality of drying zones, and the residual solvent amount of the coating film is 0.1%.
４０40 mg / m ² . The surface of the magnetic layer, the polishing layer or the back layer may be subjected to a surface smoothing process, if necessary, so that the center line average surface roughness of the magnetic layer, the polishing layer or the back layer is 0.001 to 0.3 μm (cutoff: 0.
25 mm) and cut into a desired shape to produce the magnetic recording medium or the polishing tape of the present invention. These manufacturing methods include powder pretreatment / surface treatment, kneading / dispersion, coating / drying, smoothing treatment, heat treatment, EB treatment, surface polishing treatment,
It is desirable to perform the cutting and winding steps continuously.

The smoothing process is also called a calendering process, and can smooth the surface of the magnetic layer or the polishing layer.
As the calender, a resin roll such as a metal roll, a nylon roll, or an epoxy roll can be used. Processing temperature is 30-1
It is preferable to carry out at 00 ° C. and a load of 50 to 300 kg / cm. If it is performed in multiple stages, the process is completed quickly. These are described, for example, in JP-B-40-23625 and JP-B-39-283.
No. 68, JP-B-47-38802, British Patent 1191
No. 424, JP-B-48-11336, JP-A-49-5
No. 3631, JP-A-50-112005, JP-A-51
No. 77303, Japanese Patent Publication No. 52-17404,
0-70532, JP-A-2-265672, U.S. Patent No. 3,473,960, U.S. Patent No. 4,728,569,
This is shown in U.S. Pat. No. 4,746,542. The method disclosed in Japanese Patent Publication No. 41-13181 is considered to be a basic and important technique in this field.

A magnetic recording medium or a polishing tape is wound on a desired plastic or metal reel after cutting the produced tape. It is desirable to burnish and / or clean the polishing tape immediately before or before winding. Further, it is desirable that the magnetic recording medium is subjected to the polishing treatment using the above-described polishing tape in a step immediately before or before the winding, and is additionally burnished and / or cleaned.

The varnish uses a polishing tape or a magnetic recording medium, specifically, a polished surface or a protrusion on a magnetic surface with a hard material such as a sapphire blade, a razor blade, a cemented carbide blade, a diamond blade, or a ceramic blade. Smooth and smooth. The Mohs hardness of these materials is preferably 8 or more, but is not particularly limited as long as protrusions can be removed. The shape of these materials does not need to be a blade in particular, and shapes such as a square shape, a round shape, and a wheel (these materials may be provided around a rotating cylindrical shape) can be used. The cleaning is performed by wiping the surface layer with a nonwoven fabric or the like for the purpose of removing surface dirt and excess lubricant. Such wiping materials include, for example, various types of Vilene manufactured by Japan Vilene Co., Ltd., Toraysee, Exaine manufactured by Toray Co., Ltd., Kimwipe (trade name), various polishing tapes manufactured by Fuji Photo Film Co., Ltd. Tissue paper, such as nonwoven fabric made of rayon, nonwoven fabric made of acrylonitrile, and blended nonwoven fabric can be used. These are described, for example, in JP-B-46-39309 and JP-B-58-46768.
No., JP-A-56-90429, and JP-B-58-4676.
7, JP-A-63-259830, JP-A-1-201
No. 824 and the like.

The ferromagnetic powder, abrasive powder, binder, and additives (lubricant, dispersant, antistatic agent, surface treatment agent, carbon black, abrasive powder, light shielding agent, antioxidant used in the present invention) , An antifungal agent, etc.), a solvent and a support (which may have an undercoat layer, a back layer, a back undercoat layer) or a method for producing the same are described in JP-B-56-26890 and JP-A-63-25.
No. 9830, etc. can be referred to.

[0058]

EXAMPLES Examples and comparative examples of the present invention will be shown below.
Evaluate its properties. In the examples, "parts" indicates "parts by weight".

Embodiments 1 to 6 First, the magnetic recording medium
A coating solution for a magnetic layer with the following composition A and a lower layer coating solution with the following composition B were prepared. And dried as before. Thereafter, a back coat layer was provided on the back surface of the support, heat treated, calendered, and slit to a width of 1/2 inch to produce a magnetic tape.

On the other hand, the polishing tape was prepared by uniformly kneading and dispersing the following composition C with a sand grinder, adjusting the viscosity, and applying a polishing layer coating solution containing a curing agent to a polyester support having a thickness of 6 μm to a thickness of 3 μm. And apply the bar coat as
After drying, a polishing layer is provided. The tape was slit to a width of 19 mm to prepare a polishing tape sample.

Then, the surface of the magnetic tape is polished with a polishing tape. Polishing conditions were as follows.
The polishing tape is run at various running speeds in a direction opposite to that of the magnetic tape while being brought into contact with the surface of the polishing layer of the polishing tape at a running speed of m / sec while being brought into contact with the surface of the magnetic layer. Is what you do. At this time, as shown in FIG. 1, the sliding directions of the magnetic tape and the polishing tape are not parallel (inclination angle θ = 5 °).

In each of Examples 1 to 4, as shown in Table 1 below, the polishing powder of the polishing layer of the polishing tape was diamond,
The traveling speed of the polishing tape was changed to 10 to 40 mm / min. In Example 5, the polishing powder was chromium oxide, and in Example 6, the polishing powder was alumina.

Then, the VT using the polishing tape of each embodiment and the magnetic tape polished according to the polishing conditions was used.
Table 1 shows the measurement results obtained by performing the R test and evaluating the surface properties. Initial wear is measured by VT
R was run for 1 hour, and the amount of wear of the VTR head was measured. The frequency of clogging is determined by measuring the magnetic tape after polishing
This is a result of measuring the number of times of clogging at which the output is reduced after running for 2 hours in TR.

<Comparative Examples 1 to 3> Table 1 shows Comparative Examples 1 to 3.
Are also shown. Comparative Example 1 is an example in which the magnetic surface of the magnetic tape was not polished with a polishing tape. Comparative Examples 2 and 3 were such that when the magnetic tape was polished with the polishing tape, the magnetic tape and the polishing tape were not polished. In this example, the sliding directions are parallel (θ = 0 °), and the running speed of the polishing tape is the same as that of the second and fourth embodiments.

From the results shown in Table 1, the magnetic tape polished with the polishing tapes according to Examples 1 to 6 of the present invention has a small initial wear amount and a small clogging frequency, and shows good polishing of the magnetic tape surface and insufficient fixing. Good results were obtained in Examples 1 to 4 in which the particulate components were removed, and in particular, the polishing powder of the polishing tape was diamond.

On the other hand, in Comparative Example 1, since the magnetic layer surface was not polished by the polishing tape, no particle component was removed from the surface of the polishing layer, and the amount of abrasion of the head was large, and the head was removed due to detachment of the magnetic powder and the like. The number of clogging is also increasing. Further, in Comparative Examples 2 and 3, since the polishing with the polishing tape is performed in parallel with the sliding contact direction, the removal of the insufficiently fixed particle component is insufficient, and the wear amount of the head is not so large. The frequency of head clogging is increasing.

[Magnetic layer coating liquid composition: A] Ferromagnetic metal powder (Fe—Co—Al (Co / Fe: 10 atm%, Al / Fe: 5 atm%), Hc: 1800 Oe) 100 parts Binder (PKHH: SO ₃ H groups 30% of OH groups introduced) 8 parts Binder (polyester polyurethane, sulfonic acid group 3 × 10 ⁻³ equivalent / g, epoxy group 2 × 10 ⁻⁵ equivalent / g) 6 parts Binder (polyisocyanate) , Trimethylolpropane (1 mol) TDI (3 mol) adduct) 4 parts Lubricant (2 ethylhexyl stearate / palmitic acid) 1 part Lubricant (oleyl oleate) 0.3 part Abrasive (aluminum oxide: granules) diameter 0.2 [mu] m) 6 parts solvent (methylethylketone / cyclohexanone = 2/1) 300 parts [lower Layer coating solution composition: B] inorganic powder (aluminum oxide: particle size 0.2 [mu] m) 100 parts binder (PKHH: SO ₃ H 30% introduction) 20 parts binder of the OH groups (polyester polyurethane, a sulfonic acid group 3 × 10 ^-3 eq / g, epoxy group 2 × 10 ^-5 eq / g) 8 parts binder (polyisocyanate, trimethylolpropane (1 mol of TDI (3 mol) adduct) 7 parts Lubricant (copper oleate) 0.3 part [Polishing layer coating liquid composition: C] Abrasive powder (Material: X, particle size 0.5 μm) 100 Part Carbon black (Conductex SC manufactured by Cabot Corporation) 8 parts Binder (nitrocellulose resin) 6 parts Binder (polyester polyurethane, sulfonic acid group 3 × 10 ^-3 equivalents / g, epoxy group 2 × 10 ^-5 equivalents / g 10 parts Binder (polyisocyanate, TDI (3 mol) adduct of trimethylolpropane (1 mol)) 4 parts Dispersant (oleic acid) 1 part Lubricant (butyl myristate) 1 part Diluent (Methyl ethyl ketone / cyclohexanone = 2/1) 250 parts Diluent (xylene / MIBK / toluene = 1/1/1) 250 parts

[0068]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a schematic view showing a state of polishing a magnetic layer of a magnetic recording medium with a polishing tape.

[Description of Signs] 1 Magnetic recording medium 2 Polishing tape 3 Pad θ angle

Claims (6)

[Claims] 1. A magnetic layer coating solution containing a ferromagnetic powder and a binder is coated on a non-magnetic support, dried, and the resulting tape- or sheet-shaped magnetic recording medium having a magnetic layer is polished. In a method for manufacturing a magnetic recording medium in which the surface of the magnetic layer is surface-treated by slidingly contacting with a polishing tape having a polishing layer containing a powder and a binder, the sliding direction of the polishing tape and the magnetic recording medium may be changed. A method for manufacturing a magnetic recording medium, wherein the magnetic recording medium is brought into non-parallel sliding contact. 2. The method according to claim 1, wherein the polishing layer of the polishing tape contains diamond in a polishing powder. 3. The method for manufacturing a magnetic recording medium according to claim 2, wherein diamond makes up 50% or more of the entire polishing powder. 4. The polishing tape has a total thickness of 2 to 100 μm.
3. The method according to claim 2, wherein m is m. 5. The method according to claim 1, wherein the thickness of the magnetic layer of the magnetic recording medium is 0.5.
2. The method for manufacturing a magnetic recording medium according to claim 1, wherein the thickness is from 0.05 to 3.5 [mu] m. 6. The method according to claim 1, wherein the ferromagnetic powder of the magnetic layer of the magnetic recording medium comprises a metal powder.