JPH05258301A - Apparatus and process for production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To orient a magnetic coating material effectively in the longitudinal and perpendicular directions by setting a bar-shaped magnet in such a manner that the directions of the magnetic lines of force with a nonmagnetic base are perpendicular at the ends of the poles of the magnet and are parallel between the poles, then applying the magnetic coating material on the base and curing the coating. CONSTITUTION:The nonmagnetic base 2 is made to travel along the virtual line connecting the N pole and S pole of the bar-shaped permanent magnet 1. The magnetic fields for the base 2 are perpendicular near the N pole and the S pole and are parallel between the N pole and the S pole. The magnetic coating material is applied on the base 2 by a coating head 3 in the positions between the N pole and the S pole. As a result, the magnetic powder in the magnetic coating material layer 4 is subjected to the orientation treatment by the magnetic fields parallel with the base 2 and is subjected to the orientation treatment by the perpendicular magnetic fields near the N pole or the S pole. The curing treatment of the magnetic coating material layer 4 is then executed by supplying heating air near the N pole or the S pole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium manufacturing apparatus and manufacturing method.

[0002]

BACKGROUND OF THE INVENTION For example, a coating type magnetic recording medium such as a magnetic tape is generally prepared by kneading a magnetic powder, a binder and other various additives and a solvent with a magnetic coating material to obtain a base film (such as a polyester film). It is manufactured by coating on a (non-magnetic support) and performing an orientation treatment. In this orientation treatment, an external magnetic field is applied to the magnetic coating applied to the surface of the non-magnetic support, which is continuously transferred, before the magnetic coating is dried and cured, and the easy axis of magnetization of the magnetic powder is directed in a specific direction. By orienting the film, the squareness ratio of the magnetic coating film formed by curing this coating film is increased, and it is intended to improve the recording / reproducing characteristics.

By the way, this magnetic field orientation treatment is performed by, for example, a parallel magnetic field (with respect to the non-magnetic support) formed by making N poles (or S poles) face each other with respect to the running non-magnetic support. And a perpendicular magnetic field (with respect to the non-magnetic support) formed by making the N pole and the S pole face the traveling non-magnetic support. That is, the magnetic powder in the magnetic coating layer after coating is aligned horizontally by the parallel magnetic field and then aligned vertically by the vertical magnetic field.

However, such means requires at least two sets of magnets, which is expensive and the magnetic field orientation takes time.

[0005]

DISCLOSURE OF THE INVENTION As a result of earnestly studying the above-mentioned problems, the present inventor has found that, as shown in FIG. 1, along a virtual line connecting the N pole and the S pole of a rod-shaped permanent magnet 1. When the non-magnetic support 2 is run by a magnetic field, the magnetic field composed of the N pole and the S pole of the permanent magnet 1 is transferred to the non-magnetic support 2 in the vicinity of the N pole (S pole) of the permanent magnet 1. On the other hand, it is noticed that it is in a substantially vertical direction and is substantially parallel to the non-magnetic support 2 between the N pole and the S pole of the permanent magnet 1. Utilizing this fact, it is possible to use one magnet for orientation. I realized that the treatment would be effective.

As a result of further research, when the coating head 3 applies the magnetic paint at a position between the north pole and the south pole of the permanent magnet 1, the nonmagnetic support 2 is coated. The magnetic powder in the magnetic coating layer 4 thus formed is subjected to an orientation treatment by a magnetic field substantially parallel to the non-magnetic support 2, and thereafter, the non-magnetic support 2 near the N pole (S pole) of the permanent magnet 1. It was revealed that an alignment treatment with a magnetic field substantially perpendicular to the above would be performed, and that extremely favorable results would be obtained.

After the orientation treatment by the substantially vertical magnetic field, that is, in the vicinity of the N pole (S pole) of the permanent magnet 1, for example, heated air is supplied to cure the magnetic coating layer 4. Then, the axis of easy magnetization is held in the direction perpendicular to the surface of the non-magnetic support 2, and the revelation that a magnetic recording medium having excellent recording / reproducing characteristics will be obtained.

The present invention has been achieved on the basis of such findings, and an object of the present invention is to provide a magnetic recording medium which is easily subjected to magnetic field orientation treatment and has excellent recording / reproducing characteristics. Is. An object of the present invention is an apparatus for producing a magnetic recording medium by applying a magnetic coating material to a running non-magnetic support, and the direction of magnetic force lines is substantially perpendicular to the non-magnetic support at the end. And a magnet that forms a magnetic field that is substantially parallel between them, a coating head that coats the non-magnetic support with a magnetic coating, and a magnetic coating that coats the non-magnetic support covers the magnetic pole ends of the magnet. And a curing means for curing the applied magnetic coating material at a position near the passed magnetic recording medium.

In this magnetic recording medium manufacturing apparatus, it is preferable that the coating head is arranged so that the coating of the magnetic coating material is located between the magnetic poles, and the strength of the magnet is the magnetic powder in the magnetic coating material. It is preferable that the holding power is about 5 times or more. For example, if the magnetic powder used has a coercive force of about 1500 Oersted, such as a metal-based powder, it is preferable to use a magnet having at least about 7500 Gauss. Further, the length of the magnet does not have to have any special condition, but the length may be several tens cm or less, for example, about 5 to 20 cm.

A method of manufacturing a magnetic recording medium by coating a non-magnetic support with a magnetic coating, wherein the non-magnetic support is along an imaginary line connecting the N and S poles of a rod-shaped magnet. A running step of running the body, an applying step of applying a magnetic paint to the non-magnetic support, and a magnetic paint applied at a position in the vicinity of the magnetic paint applied to the non-magnetic support passing through the magnetic pole end of the magnet. And a hardening step for hardening the magnetic recording medium.

The present invention will be described in detail below. As the magnetic powder used in the magnetic recording medium, ferromagnetic iron oxide, ferromagnetic chromium dioxide, ferromagnetic alloy powder and the like can be used. A divalent metal may be added to the ferromagnetic iron oxide. Cr, Mn, Co, Ni, C as the divalent metal
u, Zn, etc., and the iron oxide is, for example, 1 to 1
It can be added in the range of 0 atomic%. Ferromagnetic chromium dioxide Cr0 ₂ and this Na, K, Ti, V, Mn, Fe,
Metals such as Co, Ni, Tc, Ru, Sn, Ce and Pb, semiconductors such as P, Sb and Te, or CrO ₂ containing 0 to 20% by weight of oxides of these metals can be used.
Particularly, in the above-mentioned ferromagnetic iron oxide and ferromagnetic chromium dioxide, those having an acicular ratio of about 2/1 to 20/1, preferably 5/1 or more, and an average length of 0.1 to 2.0 μ are used. be able to. The ferromagnetic alloy powder has a metal content of 75% by weight or more, and 80% by weight or more of the metal content is at least one ferromagnetic metal (for example, Fe, Co, N
i, Fe-Co, Fe-Ni, Co-Ni, Fe-Co
20% by weight or less of the metal content, preferably 0.5 to 5% by weight of Al, Si, S, Sc, T.
i, V, Cr, Mn, Cu, Zn, Y, Mo, Rh, P
d, Ag, Sn, Sb, Te, Ba, Ta, W, Re,
Au, Hy, Pb, Bi, La, Ce, Pr, Nd,
It may have a composition such as B or P. The ferromagnetic alloy powder is preferably particles having a major axis of 0.5 μm or less. In addition, barium ferrite in the form of a microplate and a part of its Fe atoms are Ti, Co, Zn, V, Nb.
It is also possible to use magnetic powders substituted with one kind or two or more kinds of the above.

As the binder (binder) used for the magnetic coating film of the magnetic recording medium, a thermoplastic resin, a thermosetting resin, a reactive resin or a mixture thereof can be used in combination. For example, as the thermoplastic resin, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester -Vinylidene chloride copolymer,
Acrylic ester-styrene copolymer, methacrylic acid ester-acrylonitrile copolymer, methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-styrene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer Polymer, butadiene-acrylonitrile copolymer, polyamide resin, polyvinyl butyral, ceruce derivative (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), styrene-butadiene copolymer, polyester resin , Various synthetic rubber type thermoplastic resins (polybutadiene, polychloroprene, polyisoprene, styrene-butadiene copolymer, etc.) and mixtures thereof. As the thermosetting resin or reactive resin, phenol / formalin-novolak resin, phenol / formalin / resole resin, phenol / furfural resin, xylene / formaldehyde resin, urea resin, melamine resin, drying oil modified alkyd resin, carboxylic acid modified resin Alkyd resin, maleic acid resin-modified alkyd resin, unsaturated polyester resin, epoxy resin and curing agent (polyamine, acid anhydride, polyamide resin, etc.), terminal isocyanate polyester moisture curing type resin, terminal isocyanate polyether moisture curing type resin, Polyisocyanate prepolymer (compound having three or more isocyanate groups in one molecule obtained by reacting diisocyanate with low molecular weight triol, trimer and tetramer of diisocyanate), po Isocyanate prepolymer and resin having active hydrogen (polyester polyol, polyether polyol, acrylic acid copolymer, maleic acid copolymer, 2-hydroxyethyl methacrylate copolymer, parahydroxystyrene copolymer, etc.), and these A mixture etc. are mentioned. These binder resin components are used in an amount of about 10 to 100 parts by weight, preferably 5 to 30 parts by weight, based on 100 parts by weight of the magnetic powder.

In the magnetic coating film of the magnetic recording medium, in addition to the above-mentioned components, as the additives usually used in this field, a dispersant, a lubricant, an abrasive, an antistatic agent, an anticorrosive agent, an antifungal agent and the like are added. May be added. As the dispersant, a fatty acid having 12 to 18 carbon atoms (R ₁ COOH, R ₁ is an alkyl or alkenyl group having 11 to 17 carbon atoms), an alkali metal (Li, Na, K, etc.) of the above fatty acid, or an alkali Earth metal (Mg,
Ca, Ba, etc.) metal soap, a compound containing a fluorine of the above fatty acid ester, an amide of the above fatty acid,
Examples thereof include polyalkylene oxide alkyl phosphate ester, lecithin, trialkyl polyolefin oxyquaternary ammonium salt (alkyl has 1 to 5 carbon atoms, olefin has ethylene, propylene, etc.). In addition to these, there are higher alcohols having 12 or more carbon atoms, sulfuric acid esters and the like.
These dispersants may be added in an amount of 10 parts by weight or less based on 100 parts by weight of the magnetic powder.

As the lubricant, the above-mentioned dispersant is also effective, but dialkyl polysiloxane (wherein the alkyl group has 1 carbon atom)
~ 5), dialkoxy polysiloxane (alkoxy group has 1 to 4 carbon atoms), monoalkyl monoalkoxy polysiloxane (alkyl group has 1 to 5 carbon atoms, alkoxy group has 1 to 4 carbon atoms), phenyl Polysiloxane, fluoroalkylpolysiloxane (alkyl group has 1 to 5 carbon atoms
Individual) silicone oil, conductive fine powder such as graphite, inorganic fine powder such as molybdenum disulfide and tungsten disulfide, plastic fine powder such as polyethylene, polypropylene, polyethylene-vinyl chloride copolymer, polytetrafluoroethylene, etc. α-Olefin polymer, unsaturated aliphatic hydrocarbon which is liquid at room temperature, fatty acid ester consisting of monobasic aliphatic having 12 to 20 carbon atoms and monohydric alcohol having 3 to 12 carbon atoms, fluorocarbons, etc. Is mentioned. These lubricants are added in the range of 0.1 to 15 parts by weight with respect to 100 parts by weight of the magnetic powder.

Examples of the abrasive include fused alumina, silicon carbide, chromium oxide (Cr ₂ O ₃ ), corundum, artificial corundum, diamond, artificial diamond, garnet and emery (main components: conradam and magnetite). As these abrasives, those having a Mohs hardness of 5 or more and an average particle diameter of 0.05 to 5 μm are used, and particularly preferably 0.1 to 2 μm. And, these abrasives are 0.5 to 1 with respect to 100 parts by weight of the magnetic powder.
It is added in the range of 5 parts by weight.

As the antistatic agent, conductive fine powder such as carbon black, natural surfactant such as saponin, nonionic surfactant such as alkylene oxide type, glycerin type and glycidol type, higher alkylamines, quaternary ammonium Salts, pyridine and other heterocycles, cation surfactants such as phosphonium or sulfonium, carboxylic acid, sulfonic acid, phosphoric acid, sulfuric acid ester groups, anionic surfactants containing acidic groups such as phosphoric acid ester groups, amino acids, amino sulfones Examples thereof include amphoteric activators such as acids and sulfuric acid or phosphoric acid esters of amino alcohols. Such conductive fine powder is added in the range of 0.01 to 10 parts by weight with respect to 100 parts by weight of magnetic powder. You may add the said surfactant individually or in mixture. Although these are used as antistatic agents, they are sometimes used for other purposes such as dispersion, improvement of magnetic properties, improvement of lubricity, and coating aid.

As the rust preventive agent, phosphoric acid, sulfamide, guanidine, pyridine, amine, urea, zinc chromate, calcium chromate, strontium chromate, etc. can be used, but especially dicyclohexylamine nitrite, cyclohexylamine chromate, diisopropylamine nitrite, Volatile rust inhibitors such as diethanolamine phosphate, cyclohexylammonium carbonate, hexamethylenediamine carbonate, propylenediamine stearate, guanidine carbonate, triethanolamine nitrite, morpholine stearate (inorganic acid salts or organic acids of amines, amides or imides) Use of (salt) improves the rust prevention effect. These rust preventives are 0.0 per 100 parts by weight of the ferromagnetic fine powder.
It is used in the range of 1 to 20 parts by weight.

Examples of the fungicide include saltylanilide, bis (tributyltin oxide), mercury phenyloleate, copper naphthenate, zinc naphthenate, mercury naphthenate, pentachlorophenol, trichlorophenol, p-dinitrophenol, sorbic acid, There are butyl p-oxybenzoate, dihydroacetate and the like, and they are used in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the binder.

Materials for the non-magnetic support used in the magnetic recording medium include polyesters such as polyeletin terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polyethylene and polypropylene, cellulose triacetate and cellulose diacetate. Cellulose derivatives such as cellulose acetate butyrate and cellulose acetate propionate, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, plastics such as polycarbonate, polyimide and polyamide-imide, paper, baryta or polyethylene, polypropylene, ethylene- Papers such as papers coated or laminated with α-polyolefins having 2 to 10 carbon atoms such as butene copolymers can also be used. These non-magnetic supports may be transparent or opaque depending on the purpose of use.

Solvents used for the production of magnetic paints include ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, and ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate and glycol monoethyl ether acetate. Solvent, ether, glycol dimethyl ether, glycol monoethyl ether, glycol ether type solvent such as dioxane, tar type (aromatic hydrocarbon type) solvent such as benzene, toluene, xylene, methylene chloride, ethylene chloride, carbon tetrachloride A chlorinated hydrocarbon solvent such as chloroform, ethylene chlorohydrin, or dichlorobenzene can be appropriately selected and used.

Magnetic powder, binder, etc. are kneaded to form a magnetic coating material. At the time of kneading, the magnetic powder and each of the above-mentioned components are all introduced into the kneader at the same time or individually. In kneading and dispersing this magnetic coating material, various kneading machines such as a two-roll mill, a three-roll mill, a ball mill, a pebble mill, a tron mill, a sand glider,
Szegvari Attritor, High Speed Impeller Disperser, High Speed Stone Mill, High Speed Impact Mill, Disperser,
It is carried out with a kneader, high speed mixer, homogenizer, ultrasonic disperser or the like.

Any method may be used to apply the magnetic paint onto the non-magnetic support. For example, a gravure method, a reverse method, an extrusion method and the like can be mentioned, but other methods are also possible. Although any coating head may be used for coating, for example, the coating head 3 having the structure shown in FIG. 2 is preferable. Figure 2
Medium 5 is a slit, the length a of this slit 5 is about the width of the non-magnetic support 2, the width b of the slit 5 is about 0.03 to 2 mm, and the diameter of the liquid reservoir 6 is 10 to
It is about 15 mm. Further, it is preferable that at least the tip end side (the slit 5 side) of the coating head 3 is made of a non-magnetic material such as stainless steel or ceramics.
Then, the magnetic paint is supplied at a rate of Q ₀ from one end side,
The slit 5 is applied to the non-magnetic support 2 at a rate of Q ₁ , and the rest is discharged from the other end side at a rate of Q ₂ .

Then, the above magnetic powder, binder,
A coating type magnetic recording medium can be obtained by coating a non-magnetic support with a magnetic coating material prepared by kneading and dispersing various additives in a solvent, orienting and curing the coating material. Curing of the magnetic coating film is performed by supplying hot air heated to, for example, 40 to 90 ° C. The degree of curing of the magnetic coating film is controlled by controlling the temperature and the supply amount.

If necessary, the surface of the magnetic recording medium may be smoothed or cut into a desired shape to obtain a magnetic recording medium. The calendering treatment of the magnetic coating film is performed by metal roll and cotton roll, or synthetic resin (for example, nylon,
For example, a super calender method in which two rolls such as a polyurethane roll) or a metal roll and a metal roll are passed is used.

Hereinafter, a specific description will be given with reference to examples.

[0026]

【Example】

[Example 1] Metal magnetic powder (coercive force 1500 Oe) 100 parts by weight Sodium sulfonate group-containing polyurethane resin 10 parts by weight Sodium sulfonate group-containing vinyl chloride copolymer resin 8 parts by weight α-alumina (average particle size of 0. 2 μm) 8 parts by weight carbon black 1.5 parts by weight palmitic acid 1.5 parts by weight butyl stearate 1.0 part by weight trimethylolpropane triisocyanate 4.5 parts by weight methyl ethyl ketone / cyclohexanone / toluene 280 parts by weight From the above composition Magnetic paint (viscosity 280c at 30 ℃
ps) is the coating head 3 made of alumina ceramics shown in FIG. 2 (the diameter of the liquid reservoir 6 is 15 mm, the width b of the slit 5 is 0.2 mm, the distance between the non-magnetic support 2 and the slit 5 is Is 1 mm) (Q ₀ = 24 l / min),
At the rate of Q ₁ (12 l / min) from the slit 5, FIG.
The non-magnetic support (thickness 10 μm, width 1
50 mm polyethylene terephthalate) 2 was applied at a coating speed of 100 m / min. The coating amount is such that the thickness after drying is 2.8 μm. Also, permanent magnet 1
Has a length of 12 cm and a magnet strength of 10,000 Gauss.

Then, air of about 60 ° C. is supplied toward the applied magnetic coating layer 4 in the vicinity of the N extreme of the permanent magnet 1 to cure the magnetic layer after the orientation treatment. After that, calendering was performed with a 7-step calender having a roll having a linear pressure of 300 Kg / cm ² and a temperature of 90 ° C., and slit to a predetermined width to obtain a magnetic tape. [Comparative Example 1] A magnetic tape was obtained by standing the permanent magnet 1 used in Example 1 as shown in FIG.

[Comparative Example 2] The same procedure as in Example 1 was carried out except that the air supply at about 60 ° C. was stopped toward the applied magnetic coating layer 4 in the vicinity of the N extreme of the permanent magnet 1. I got a magnetic tape. [Characteristics] Residual magnetic flux density (Br, unit: G), squareness ratio (Br / Bs), coercive force (Hc, unit: Oe), and C for the magnetic tapes obtained in the above examples. / N (unit: dB) was measured, and the results are shown in Table 1.

Table 1 Longitudinal direction Vertical direction Br Br / Bs Hc Br Br / Bs Hc C / N Example 1 2450 0.768 1450 1540 0.502 1330 +1.9 Comparative Example 1 2300 0.721 1420 1300 0.423 1240 +0.5 Comparative Example 2 2250 0.736 1420 1260 0.420 1270 +0.7 According to this, in the present example, the longitudinal and vertical orientation treatments are effectively performed, the squareness ratio is large, and C / It can be seen that N is also high, and the one having excellent recording / reproducing characteristics is obtained.

[0030]

[Effect] According to the present invention, the longitudinal and vertical orientation treatments are effectively performed, the squareness ratio is large, and C /
N is also high, and the one having excellent recording / reproducing characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus for manufacturing a magnetic recording medium of the present invention.

FIG. 2 is a schematic view of a coating head used in a magnetic recording medium manufacturing apparatus of the present invention.

FIG. 3 is a schematic diagram of a magnetic recording medium manufacturing apparatus of a comparative example.

[Explanation of symbols]

 1 permanent magnet 2 non-magnetic support 3 coating head 4 magnetic paint layer 5 slit 6 liquid reservoir

Claims (4)

[Claims] 1. An apparatus for producing a magnetic recording medium by applying a magnetic coating material to a running non-magnetic support, wherein magnetic lines of force are substantially perpendicular to the non-magnetic support at an end portion. , A magnet forming a magnetic field that is substantially parallel to each other, a coating head for coating the non-magnetic support with the magnetic coating, and a magnetic coating applied to the non-magnetic support passed through the magnetic pole ends of the magnet. An apparatus for producing a magnetic recording medium, comprising: a curing unit configured to cure the applied magnetic coating material at a position in the vicinity thereof. 2. An apparatus for manufacturing a magnetic recording medium according to claim 1, wherein the coating head is arranged so that the coating of the magnetic paint is located between the magnetic poles. 3. The strength of the magnet is about 5 times or more the holding force of the magnetic powder in the magnetic paint.
Magnetic recording medium manufacturing apparatus. 4. A method for producing a magnetic recording medium by applying a magnetic coating material to a non-magnetic support, comprising N of a rod-shaped magnet.
A running step of running the non-magnetic support along an imaginary line connecting the pole and the S pole, a coating step of applying a magnetic coating material to the non-magnetic support, and a magnetic coating on the non-magnetic support. And a curing step of curing the applied magnetic coating material at a position in the vicinity of where the coating material has passed through the magnetic pole ends of the magnet.