JPH04318326A - Apparatus for producing magnetic recording medium - Google Patents

Abstract

PURPOSE:To produce the high-quality magnetic recording medium with good productivity by providing a traveling means which allow a base to be coated with a magnetic coating material to travel through the spacing between a coating head and a magnet. CONSTITUTION:The coating head 1 for the magnetic coating material having a liquid reserving part 5 in an outlet part and the magnet 6 provided to face the liquid reserving part 5 of this head 1 are provided. The base 7 to be coated with the magnetic coating material is made to travel through the spacing between the coating head 1 and the magnet 6. The nonmagnetic base 7 is coated thereon with the coating material at 300m/min coating rate in such a manner that the dry film thickness attains 4mum. Not only the coating of the base with the magnetic coating material with good coatability is executed but also the video output of the resulted magnetic recording medium is high. The requirements for the higher coating speeds and the thinner coated films are met and the high-grade magnetic recording medium is produced with the good productivity.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing magnetic recording media.

0002

BACKGROUND OF THE INVENTION Magnetic recording media such as magnetic tapes are obtained by coating magnetic paint on a non-magnetic support, and the coating methods include roll coating, gravure coating, extrusion coating, slide bead coating,
Application methods such as curtain coating are known. Among them,
The extrusion coating method is said to be superior because it provides a uniform coating thickness.

However, conventional methods are said to be unable to meet the increasing demands for faster coating speeds and thinner coatings.As a way to solve these problems, as shown in FIG. Non-magnetic support 1
Extrusion port 1 of coating head 11 without supporting the back side of
2 is pressed against the support 10, and a permanent magnet 13 of 50 to 5000 Gauss is placed on the opposite side of the extrusion port 12 with the support 10 in between, and the magnetic paint is discharged from the extrusion port 12 of the coating head 11. A method for manufacturing a magnetic recording medium has been proposed (Japanese Patent Application Laid-Open No. 62-95170) in which the magnetic recording medium is coated on the support 10.

By the way, although studies have been made on this proposed technique, it has not been sufficient to meet the demands for faster coating speeds and thinner coated films. That is,
With this proposed technique, coating unevenness occurred, and the recording and reproducing characteristics of the obtained magnetic recording medium were poor.

[0005]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a technology that can meet the demands for faster coating speeds and thinner coating films, and that can manufacture high-quality magnetic recording media with high productivity. The object of the present invention is to provide a coating head for magnetic paint having a liquid reservoir at the outlet, a magnet disposed opposite to the liquid reservoir of the coating head, and a support to which the magnetic paint is applied. This is achieved by a magnetic recording medium manufacturing apparatus characterized by comprising a traveling means for traveling between a coating head and a magnet.

The magnet may be a permanent magnet or an electromagnet, and the intensity of the magnetic flux applied by these magnets may be about 300 to 3000 Gauss. The liquid reservoir of the coating head for applying the magnetic paint may have any shape, and specific examples include structures shown in FIGS. 1 to 3. In each figure, 1 is a coating head, 2 is a front edge surface, 3 is a back edge surface, 4 is a flow path through which magnetic paint is discharged between the front edge surface 2 and the back edge surface 3, and 5 is a flow path through which magnetic paint is discharged. A liquid reservoir configured at the outlet of the flow path; 6 a magnet disposed opposite the liquid reservoir 5; 7 a predetermined traveling mechanism that moves the coating head 1;
This is a non-magnetic support that can be run between the magnet 6 and the magnet 6.

[0007] As the magnetic powder used in the magnetic paint for constructing the magnetic recording medium, ferromagnetic iron oxide, ferromagnetic chromium dioxide, ferromagnetic alloy powder, etc. can be used. A divalent metal may be added to the ferromagnetic iron oxide. Examples of divalent metals include Cr, Mn, Co, and Ni. Ferromagnetic chromium dioxide is CrO2 and Na, K, Fe, Mn.
Metals such as P, semiconductors such as P, or materials to which oxides of these metals are added can be used. The ferromagnetic metal 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 (e.g., Fe, Co).
, Ni), and examples of the ferromagnetic metal powder include Fe.
-Co, Fe-Ni, Fe-Al, Fe-Ni-Al,
Co-Ni, Fe-Co-Ni, Fe-Ni-Al-Z
n, Fe-Al-Si, etc. In addition, micro-plate-like barium ferrite and some of its Fe atoms are Ti, Co,
Magnetic powder substituted with atoms such as Zn and V can also be used.

As the binder used in the magnetic paint for forming the magnetic recording medium, a thermoplastic resin, a thermosetting resin, a reactive resin, or a mixture thereof can be used in combination. For example, thermoplastic resins include 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,
Examples include urethane elastomers, vinylidene chloride-acrylonitrile copolymers, butadiene-acrylonitrile copolymers, polyamide resins, cellose derivatives, styrene-butadiene copolymers, and polyester resins. As the thermosetting resin or reactive resin, phenol-
Examples include formalin-novolac resin, phenol-formalin-resol resin, urea resin, melamine resin, unsaturated polyester resin, terminal isocyanate polyester moisture-curing resin, terminal isocyanate polyether moisture-curing resin, polyisocyanate prepolymer, and the like. These binder resin components are contained in an amount of about 5 to 100 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the magnetic powder.
Used in parts by weight range.

[0009] Other components added to the magnetic paint for constituting the magnetic recording medium may include a dispersant, a lubricant, an abrasive, an antistatic agent, a rust preventive, a fungicide, and the like. Dispersants include fatty acids having 12 to 18 carbon atoms, metal soaps made of alkali metals or alkaline earth metals of the above-mentioned fatty acids, amides of the above-mentioned fatty acids, polyalkylene oxide alkyl phosphates, lecithin, trialkyl polyolefin oxy Examples include quaternary ammonium salts. In addition, there are also higher alcohols having 12 or more carbon atoms, sulfuric esters, and the like. These dispersants may be added in an amount of 10 parts by weight or less per 100 parts by weight of the magnetic powder.

As a lubricant, the above-mentioned dispersants are effective, but silicone oils such as dialkyl polysiloxane, dialkoxy polysiloxane, monoalkyl monoalkoxy polysiloxane, conductive fine powder such as graphite, etc.
Examples include fine inorganic powders such as molybdenum disulfide and tungsten disulfide, fine plastic powders such as polyethylene and polypropylene, and fatty acid esters. These lubricants are added in an amount of 0.1 to 15 parts by weight per 100 parts by weight of the magnetic powder.

[0011] As the polishing agent, alumina, α-iron oxide,
Examples include titanium oxide, silicon carbide, and chromium oxide. These abrasives have a Mohs hardness of 5 or more and an average particle size of 0.05 to 5 μm. These abrasives are added in an amount of 0.5 to 15 parts by weight per 100 parts by weight of the magnetic powder. Examples of the antistatic agent include conductive fine powder such as carbon black. Such conductive fine powder is magnetic powder 10
It is added in an amount of 0.01 to 10 parts by weight relative to 0 parts by weight.

As the rust preventive agent, use of a volatile rust preventive agent such as dicyclohexylamine nitrite, cyclohexylamine chromate, or diisopropylamine nitrite improves the rust preventive effect. These rust inhibitors are used in an amount of 20 parts by weight or less per 100 parts by weight of the ferromagnetic fine powder. Antifungal agents include copper naphthenate, zinc naphthenate, mercury naphthenate, pentachlorophenol, trichlorophenol, p-dinitrophenol, sorbic acid, butyl p-oxybenzoate, dihydroacetoic acid, etc. It is used within a range of 5 parts by weight or less.

Solvents used in the production of magnetic paints include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, and esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and acetic acid glycol monoethyl ether. Glycol ether-based solvents such as ether, glycol dimethyl ether, glycol monoethyl ether, and dioxane, tar-based (aromatic hydrocarbon) solvents such as benzene, toluene, and xylene, methylene chloride, ethylene chloride, and tetrachloride. Chlorinated hydrocarbon solvents such as carbon, chloroform, ethylene chlorohydrin, and dichlorobenzene can be appropriately selected and used.

Magnetic powder, binder, etc. are kneaded to make a magnetic paint. During kneading, the magnetic powder and each of the above-mentioned components are fed into a kneading machine either all at the same time or individually one after another. For kneading and dispersing this magnetic paint, various types of kneading machines are used, such as two-roll mills, three-roll mills, ball mills, sand gliders, high-speed impeller dispersion machines,
This is done using high-speed stone mills, high-speed impact mills, dispersers, kneaders, high-speed mixers, homogenizers, ultrasonic dispersers, etc.

[0015] Then, a coated magnetic recording medium is produced by applying, orienting, and drying a magnetic paint in which the above-mentioned magnetic powder, binder, and various additives are kneaded and dispersed in a solvent onto a non-magnetic support. can get. In the case of a multilayer magnetic recording medium, a magnetic paint is coated on a nonmagnetic support and dried, and this process is repeated to form two or more magnetic layers by continuous coating, or a simultaneous multilayer coating method is used. May be used.

By such a method, the magnetic layer coated on the support is subjected, if necessary, to an orientation treatment for the magnetic powder in the magnetic layer, and then the magnetic layer is dried. In addition, a magnetic recording medium can be obtained by subjecting it to surface smoothing treatment or cutting it into a desired shape, if necessary. Materials for non-magnetic supports used in magnetic recording media include polyesters such as polyethylene tephthalate, polyolefins such as polyethylene and polypropylene, cellulose derivatives such as cellulose acetate butyrate and cellulose acetate propionate, and polychloride. Vinyl resins such as vinyl and polyvinylidene chloride are used. Of course, it is not limited to these.

[0017]

【Example】

[Example 1] The components of the magnetic paint shown below were placed in a kneader and kneaded for 1.5 hours. After adding 90 parts of diluent,
Each component was uniformly dispersed, and 5 parts by weight of Coronate L (manufactured by Nippon Polyurethane Industries, Ltd.) was added to prepare a magnetic paint.

[0018]
Co-containing γ-Fe2 O3 (Hc9
00 Oersted, BET value 50m2 /g,
Average particle size 0
．． 16 μ) Vinyl chloride resin containing 100 parts by weight of potassium sulfonate (MR110 from Nippon Zeon Co., Ltd.)

Polyester polyurethane containing 10 parts by weight of sodium sulfonate (
Toyobosha UR-8300)


5 parts by weight alumina

1 part by weight carbon black (average particle size 40mμ)
1 part by weight mystylic acid

1 part by weight butyl stearate

1 part by weight methyl ethyl ketone
10 parts by weight cyclohexanone

10 parts by weight toluene

10 parts by weight. Using this magnetic paint, as shown in FIG. was used to coat the non-magnetic support 7 at a coating speed of 300 m/min to a dry film thickness of 4 μm.

Thereafter, a video magnetic tape was manufactured through the usual steps. [Example 2] In Example 1, the coating speed was changed to 100 m/
The same procedure was carried out by setting min. [Example 3] The same procedure as in Example 1 was carried out using the coating head shown in FIG. 2 instead of using the coating head shown in FIG.

[Example 4] The same procedure as in Example 1 was carried out using the coating head shown in FIG. 3 instead of the coating head shown in FIG. [Comparative Example 1] The same procedure as in Example 1 was carried out using the coating head shown in FIG. 4 without the liquid reservoir, instead of using the coating head shown in FIG.

[Comparative Example 2] The same procedure as in Example 2 was carried out using, instead of using the coating head shown in FIG. 1, the coating head shown in FIG. 4 without the liquid reservoir section.

[0022]

[Characteristics] The coatability and dropout of the magnetic tapes obtained in each of the above examples were investigated, and the results are shown in Table 1 below.
Table 1
Magnet strength Spreadability Dropout
(Gauss)
(pcs/min) Example 1
300 ◎
7
2000 ◎
8 Example 2 300
◎ 7
2000
◎ 7 Example 3
1000 ○
11 Example 4 10
00 ○ 10
Comparative example 1 300
× 30
2000 ×
40 Comparative Example 2
300 △
25 2
000 Δ30 In the coating property, ◎ indicates extremely good, ◯ indicates good, and × indicates that coating defects are observed throughout.

[0023] For dropout, use a dropout counter VD-5M manufactured by Victor Japan Co., Ltd.
longer than μsec and 2 of the output of the Rf envelope
Assuming that the output has decreased by 0dB or more as one dropout,
The total length was measured and the average value per minute was determined. According to this, it can be seen that the coating properties of the magnetic paint during manufacturing of the magnetic recording medium of the present invention are good, the video output of the magnetic recording medium is high, and a high-quality magnetic recording medium can be obtained with good productivity.

[0024]

[Effects] The magnetic recording medium manufacturing apparatus according to the present invention includes a magnetic paint coating head having a liquid reservoir at the outlet, a magnet disposed opposite to the liquid reservoir of the coating head, and a magnetic paint coating head having a liquid reservoir at the outlet. Since the magnetic coating is provided with a traveling means for causing the support to be coated to pass between the coating head and the magnet, the magnetic coating can be coated with good coating properties, and the video output of the obtained magnetic recording medium is high. It has the advantage of being able to provide high quality magnetic recording media with good productivity.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a main part of a first embodiment of a magnetic recording medium manufacturing apparatus of the present invention.

FIG. 2 is a schematic diagram of a main part of a second embodiment of the magnetic recording medium manufacturing apparatus of the present invention.

FIG. 3 is a schematic diagram of a main part of a third embodiment of the magnetic recording medium manufacturing apparatus of the present invention.

FIG. 4 is a schematic diagram of main parts of a conventional magnetic recording medium manufacturing apparatus.

[Explanation of symbols]

1 Application head 2 Front edge surface 3 Back edge surface 4 Magnetic paint discharge channel 5 Liquid reservoir part 6 Magnet 7 Non-magnetic support

Claims (1)

[Claims] 1. A magnetic paint coating head having a liquid reservoir at an outlet, a magnet disposed opposite to the liquid reservoir of the coating head, and a support to which the magnetic paint is applied to the coating head. 1. An apparatus for producing a magnetic recording medium, comprising: a traveling means for causing the traveling means to travel between the magnet and the magnetic recording medium.