JP2001344749A - Device for manufacturing magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a devise for manufacturing a magnetic recording medium suitable for high-density and large-capacity recording, capable of improving the orientation of magnetic powder contained in magnetic paint while maintaining the surface quality of a magnetic layer highly accurate. SOLUTION: This manufacturing device M1 for drying magnetic paint 10 while orienting magnetic powder contained in the same coated on a non- magnetic support 9 is provided with a magnetic field generator 3 for orienting the magnetic powder, and a dryer 4 including a nozzle 4b having an opening 4c for supplying hot air used to dry the magnetic paint 10, and an adjusting mechanism 4a for adjusting the temperature an the amount/velocity of the hot air. The openings 4c of the nozzle 4b are disposed in both surfaces of the non-magnetic support 9 in the magnetic field generator 3 so as to supply the hot air over the full length of the advancing direction A of the non-magnetic support 9. The hot air blowing-out positions of the opening 4c of the nozzle are regularly shifted at equal intervals between one and the other surfaces of the non-magnetic support 9. A tension (N/m) per unit width of the non- magnetic support 9 in the advancing direction is set in the range of 16 to 64 N/m.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus for manufacturing a coating type magnetic recording medium, and more particularly to an apparatus for manufacturing a magnetic recording medium suitable for manufacturing a high density recording medium.

[0002]

2. Description of the Related Art Generally, as an audio tape or video tape, a magnetic material such as metal fine particles, a binder, a dispersant, a lubricant, etc. are kneaded and dispersed in an organic solvent on a non-magnetic support such as a polyester film. A so-called coating type magnetic recording medium in which a magnetic layer is formed by applying a magnetic paint formed as described above is used.

The coating type magnetic recording medium is designed to minimize the output loss (spacing loss) by super-smoothing the surface in order to achieve high-density recording.

[0004] In order to achieve high-density recording, studies have been made on improving the magnetic properties of this coating type magnetic recording medium. For example, a material having a coercive force exceeding 160 kA / m in fine metal particles has been developed. In addition, the coercive force of the magnetic material is enhanced, and the particles of the magnetic material are made finer.

By the way, when manufacturing a coating type magnetic recording medium, a so-called orientation is performed in which the major axis of the magnetic powder in the magnetic paint is oriented in a certain direction. Therefore, the improvement of the orientation has been studied. That is, in order to manufacture a magnetic recording medium compatible with high-density recording, it is necessary to secure an external magnetic field necessary to direct a magnetic powder in a magnetic coating material having a high coercive force in a certain direction, and Studies have been made to make it easier to apply a torque in order to direct in a certain direction.

[0006] Specifically, the size of a magnet for generating an external magnetic field has been studied.
There is a limit due to problems such as an increase in manufacturing cost and a need for a large installation space. The use of a superconducting magnet was also considered, but this requires the use of liquid helium, which has the problem of significantly increasing running costs.

Therefore, by employing a so-called magnetic field drying method in which the orientation of the magnetic powder in the magnetic paint and the drying of the magnetic paint are simultaneously performed, the orientation of the magnetic powder in the magnetic paint can be efficiently performed. Technology is used.

[0008]

However, in the magnetic field drying method, only the surface layer of the magnetic paint can be dried with a limited magnet length, and excellent magnetic characteristics cannot be obtained.
To completely dry magnetic paint in a limited magnetic field,
Increasing the wind power of the hot air for drying degrades the surface accuracy due to the waviness and surface roughness of the surface of the magnetic layer, increasing the spacing loss, improving the orientation and smoothing the surface. However, there was a problem that they could not be compatible.

On the other hand, a plurality of orienting devices provided with a magnet for generating a magnetic field and a dryer for drying the magnetic paint are installed, and the temperature and the amount or speed of the warm air sent from the plurality of orienting devices are provided. Have been proposed to be adjusted independently of each other.

However, in the above-described manufacturing apparatus, a space is required to install a plurality of orientation devices each including a magnet for generating a magnetic field and a dryer for drying the magnetic paint. However, there have been problems such as an increase in cost and an increase in cost.

In order to solve the above-mentioned problems, in the present invention, the orientation of the magnetic powder in the magnetic paint is improved while maintaining the surface properties of the magnetic layer with high precision, and the production is performed at a small space and at low cost. The present invention provides a magnetic recording medium manufacturing apparatus suitable for high-density, large-capacity recording.

[0012]

SUMMARY OF THE INVENTION A magnetic recording medium manufacturing apparatus according to the present invention performs drying of a magnetic paint while orienting magnetic powder in the magnetic paint applied on a non-magnetic support in a certain direction. A nozzle having a magnetic field generator for orienting the magnetic powder and having an opening for supplying hot air for drying the magnetic paint, and the temperature and the amount or speed of the hot air are respectively adjusted. And a dryer having an adjusting mechanism.The nozzle opening is disposed on both sides of the non-magnetic support in the magnetic field generator so as to supply hot air over the entire length of the non-magnetic support in the traveling direction. In the openings of the nozzles arranged on both sides of the non-magnetic support, the positions of the hot air outlets were regularly shifted at regular intervals on one side and the other side of the non-magnetic support. Have a relationship and pass through the device Tension per unit width of the non-magnetic support (N / m) is 16 in the traveling direction of the non-magnetic support that
It is within the range of 64 N / m.

According to the configuration of the present invention described above, the nozzle opening is disposed in the magnetic field generator so as to supply hot air over the entire length of the non-magnetic support in the traveling direction. It is possible to supply uniform warm air over the entire area. In addition, the dryer has an adjustment mechanism so that the temperature and the amount of air or the speed of the hot air can be adjusted individually, thereby preventing the paint from waving due to wind pressure, while maintaining the high surface properties of the magnetic paint. It is possible to adjust so that the magnetic powder in the magnetic paint is efficiently oriented and dried sufficiently.

Further, the openings of the nozzle are arranged on both sides of the non-magnetic support, and the positions of the outlets of the warm air are regularly spaced at regular intervals on one side and the other side of the non-magnetic support. By having a staggered relationship, the effect of the warm air on the running state of the non-magnetic support becomes very small,
The balance of the forces on the non-magnetic support is maintained. Moreover, the tension (N / m) per unit width of the non-magnetic support in the traveling direction of the non-magnetic support passing through the apparatus is 16 to
By adopting a configuration in which the hot air blowing holes are regularly shifted at equal intervals on one surface side and the other surface side of the non-magnetic support, it is set to be within the range of 64 N / m. Even if the tension is lowered to a relatively low value, the magnetic powder can be dried and oriented without any problem.

[0015]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for manufacturing a magnetic recording medium for drying a magnetic paint while orienting magnetic powder in the magnetic paint applied on a non-magnetic support in a certain direction, A nozzle having a magnetic field generator for orienting the magnetic powder and having an opening for supplying hot air for drying the magnetic paint,
A dryer having an adjusting mechanism adapted to adjust the temperature and the flow rate or the speed of the hot air, respectively, so that the opening of the nozzle supplies the hot air over the entire length of the non-magnetic support in the traveling direction. In the magnetic field generator, arranged on both sides of the non-magnetic support in the magnetic field generator, at the opening of the nozzle arranged on both sides of the non-magnetic support, the position of the outlet of hot air is one of the non-magnetic support The surface side and the other surface side have a regularly shifted relationship at equal intervals, and the tension per unit width (N / N) of the non-magnetic support in the traveling direction of the non-magnetic support passing through the device. m) is in the range of 16 to 64 N / m.

According to the present invention, in the above-described apparatus for manufacturing a magnetic recording medium, the opening width of the opening of the nozzle in the traveling direction is 1 to 1.
The configuration is set to 8 mm.

Further, according to the present invention, in the above-described apparatus for manufacturing a magnetic recording medium, the interval between nozzle openings is set to 30 to 60 mm.

Further, according to the present invention, in the above-described apparatus for manufacturing a magnetic recording medium, the flow rate of warm air is set to be 600 to 2000 m ³ per hour.

FIG. 1 shows a schematic diagram (schematic diagram) of an apparatus for manufacturing a magnetic recording medium according to an embodiment of the present invention. As shown in FIG. 1, the apparatus for manufacturing a magnetic recording medium includes an unwinding device 1 that unwinds a non-magnetic support 9 wound in a coil shape.
A coating device 2 for applying a magnetic paint 10 on a non-magnetic support 9; an orientation device M1 for performing orientation and hot-air drying; a drying device 6 for performing only hot-air drying; And a winding device 8 that winds the non-magnetic support member 9 having undergone a series of processing in a coil shape.

As shown in FIG. 2, the orientation device M1 includes a magnet 3 for generating a magnetic field, a magnetic paint 1
A dryer 4 for drying the magnetic paint 10 and a solvent suction device 5 for sucking and recovering an organic solvent generated when the magnetic paint 10 is dried are provided.

The magnet 3 forms a magnetic field for orienting the magnetic powder in the magnetic paint 10. For example, the traveling direction of the non-magnetic support 9 to which the magnetic paint 10 is applied (indicated by an arrow A in FIG. 1). (Direction) is constituted by a plurality of wound solenoid coils. This solenoid coil has a non-magnetic support 9 coated with a magnetic paint 10.
Is formed in a size that can run inside it,
While the non-magnetic support 9 runs in the solenoid coil,
The magnetic powder in the magnetic paint 10 is formed to have a length that can complete the orientation of the magnetic powder. The strength of the magnetic field formed by the magnet 3 is preferably at least twice the coercive force of the magnetic powder. More preferably, it is 2.5 times or more.

The dryer 4 blows warm air for drying the magnetic paint 10 applied on the nonmagnetic support 9, and is located behind the magnet 3 with respect to the traveling direction of the nonmagnetic support 9. Attached to. This dryer 4
Is a nozzle 4b having an opening 4c,
And an adjusting mechanism 4a for adjusting the temperature and the amount or speed of the warm air blown out from the opening 4c. And
The opening 4c of the nozzle 4b is provided at the opening inside the magnet 3, that is, at the portion through which the nonmagnetic support 9 passes so that the opening 4c of the nozzle 4b opens toward the nonmagnetic support 9.

By the way, if at least the opening 4c is provided above the non-magnetic support 9 on which the magnetic paint 10 is applied, it is possible to perform hot-air drying. If the guide roller is provided on the lower side where the magnetic paint 10 is not applied, for example, the nonmagnetic support 9 can be supported. However, in order to provide a guide roller inside the magnet 3, it is necessary to increase the interval between the magnet 3 and the non-magnetic support 9, and the magnetic field from the magnet 3 is weakened by increasing the interval.

On the other hand, as shown in FIG. 2, openings 4c are provided above and below the nonmagnetic support 9, and these openings 4c are provided.
If the warm air is blown out from above, the non-magnetic support 9 can be held in a well-balanced manner by the pressure of the warm air blown from above and below without providing a guide roller inside the magnet 3.

FIG. 3A is a sectional view of a main part of the orientation device M1 shown in FIG. In the present embodiment, as shown in FIG. 2 and FIG. 3A, the slit 4d of the lower outlet 4c is arranged at the center of the two slits 4d (interval D) of the upper outlet 4c. The slits 4d of the upper outlet 4c are arranged at the middle position of the two slits 4d of the outlets, and the slits 4d are alternately arranged at equal intervals (interval D / 2). By arranging the slits 4d at equal intervals in this manner, the balance of the force applied to the tape by the warm air can be improved.

When the slits 4d are formed at the same position in the upper and lower openings 4c, the accuracy of the alignment of the slits 4d in the upper and lower openings 4c and the slight difference in the wind speed and the amount of air flowing out of the upper and lower slits 4d are determined. The position at which the hot air hits the upper and lower parts, and the balance of the force applied to the tape of the non-magnetic support 9 by the hot air blown out from the slit 4d is lost. If, for example, the direction and amount of the positional shift of the slits 4d vary among the plurality of slits 4d, the tape may flutter.

Therefore, if the positions of the upper and lower slits 4d are shifted by a fixed amount and are arranged at equal intervals as in the present embodiment, the tape runs in a gentle curve (not shown), so that the positioning accuracy can be improved. Even if there is a slight difference in the airflow and the amount of air flow, the amplitude of the tape curve and the position of the peak change only slightly. Therefore, the influence on the running state is extremely small, and the balance of the force applied to the tape can be maintained.

In the present embodiment, the tension (N / m) per unit width of the tape of the non-magnetic support 9 in the traveling direction A of the non-magnetic support 9 is in particular 16 to 64 N / m.
Set to the range. More preferably, it is about 32 N / m. The value of 32 N / m corresponds to applying a tension of about 2 kg weight (kgw) to a tape having a width of, for example, 24 inches.

The tension per unit width of the tape of the ordinary nonmagnetic support 9 is 100 N / m or more. When the tension is increased, the tape tends to be easily stretched in the advancing direction while being heated for drying. On the contrary,
In the present embodiment, since the positions of the upper and lower slits 4d are shifted by a fixed amount, the balance of the force applied to the tape can be maintained. A good running state can be achieved without rattling. Therefore, the present embodiment has an advantage that the tension can be reduced, thereby preventing the tape from being stretched.

Further, in the present embodiment, FIG.
3A shows an enlarged view of a part of FIG.
In c, the opening width d1 of the slit 4d is set in the range of 1 to 8 mm. And the interval D of each slit 4d
Is preferably set in the range of 30 to 60 mm. That is, the width d2 in the traveling direction of the partition wall 4e between the slits 4d is
Preferably, it is set in a range of about 30 to 50 mm.

FIG. 4 is a perspective view of a main part of the dryer 4 below the nonmagnetic support 9. As shown in FIG.
In this case, eight elongated rectangular slits 4d are provided in the opening 4c of the dryer 4 as hot air blowing holes. In FIG. 4, the long side of the slit 4d is the non-magnetic support 9
Is slightly longer than the width. By providing the elongated rectangular slits 4d in this way, the non-magnetic support 9
Hot air can be uniformly applied in the width direction, and the speed of the hot air can be made sufficient for drying.

The rectangular slit 4d has, for example, a width of about 1 to 8 mm on the short side and a width of about -50 to +50 mm with respect to the width of the nonmagnetic support 9 in the same manner as the above-described opening width d1. It is desirable to arrange a plurality of about 8 to 10 pieces along the running direction A of the non-magnetic support 9 in the shape of a circle.

The solvent suction device 5 has a suction nozzle 5b for sucking the organic solvent evaporated from the magnetic paint 10, and a solvent recovery device 5a for separating and recovering the organic solvent from the mixed vapor of the air and the organic solvent. Is attached to the front side of the magnet 3 with respect to the traveling direction of the nonmagnetic support 9. The suction nozzle 5b functions as an exhaust duct. Further, the solvent recovery device 5a is provided with an exhaust device for discharging the vapor from which the organic solvent has been separated.

Then, the hot air blown to the non-magnetic support 9 by the dryer 4 and the solvent suction device 5 is directed in a direction opposite to the traveling direction of the non-magnetic support 9, that is, in FIG.
The warm air is blown out in the direction indicated by the middle arrow B to dry the magnetic paint 10. Further, the dryer 4 is configured such that the temperature and the amount or speed of the hot air to be sent can be independently controlled by the adjusting mechanism 4a.

Further, although not shown, a DC power supply for supplying a DC current to both ends of the magnet 3 and a cooling water supply port for cooling heat generated in the magnet 3 are provided in the orientation device M1. .

As described above, the control of the temperature and the amount or speed of the warm air is performed by the adjusting mechanism 4a of the orientation device M1. And it is preferable that the wind speed of the warm air in the orientation device M1 is set within a range of 1 to 20 m / sec. More preferably, it is in the range of 5 to 15 m per second. If the wind speed is lower than this, drying is not sufficiently performed, and if the wind speed is higher than this, the ripples of the paint become remarkable, and the surface properties rapidly deteriorate. Further, it is preferable that the flow rate of the warm air in the orientation device M1 is set within a range of 600 to 2000 m ³ per hour. More preferably, it is set to about 1000 m ³ per hour. If the air volume is less than this, drying will not be performed sufficiently, and if it is more than this, the coating will be remarkably waved and the surface properties will be rapidly deteriorated.

The temperature of the warm air of the orientation device M1 is controlled by the nozzle 4b
It is preferable that the temperature is set in the range of 30 to 150 ° C. as measured at the opening 4c. More preferably 70
It is in the range of -120 ° C. If the temperature is too low, drying is not performed sufficiently. On the other hand, when the temperature is too high, bumping of the solvent occurs, which is not only dangerous but also deteriorates the surface properties, which is not preferable.

The magnetic recording medium 20 is manufactured by passing the magnetic recording medium manufacturing apparatus having the above configuration through the non-magnetic support 9 coated with the magnetic paint 10.

As shown in FIG. 5, a magnetic recording medium 20 has a magnetic material, a condensing agent, a dispersing agent, a lubricating material and a lubricating material on a flexible non-magnetic support 9 such as a polyester film. Paint 1 prepared by kneading and dispersing agents in an organic solvent
By applying 0, a magnetic layer is formed.

The magnetic material used for the magnetic paint 10 may be a conventional material such as maghemite powder, cobalt-coated maghemite, cobalt-doped maghemite, magnetite, cobalt-coated magnetite, or cobalt-doped magnetite, or Fe, Co, Ni, or the like. Metal, Fe-Co, Fe-N
i, Fe-Al, Fe-Ni-Al, Fe-Al-P,
Fe-Ni-Si-Al, Fe-Ni-Si-Al-M
n, Fe-Mn-Zn, Fe-Ni-Zn, Co-N
i, Co-P, Fe-Co-Ni, Fe-Co-Ni-
Cr, Fe-Co-Ni-P, Fe-Co-B, Fe-
Co-Cr-B, Mn-Bi, Mn-Al, Fe-Co
Alloys such as -V, iron nitride, iron carbide and the like.

Most commonly, Fe alone or Fe
-Co, Fe-Ni, Fe-Co-Ni alloys
And / or Si added for the purpose of preventing sintering
It is. The specific surface area of these metal powders is 20 to 90 m^Two/
g, preferably 25 to 70 m ^Two/ G
No. In addition, hexagonal plate-like ferrite can be used.
Barium ferrite of M type, W type, Y type, Z type
Trontium ferrite, calcium ferrite, lead
Ferrites and, for the purpose of controlling coercive force,
o-Ti, Co-Ti-Zn, Co-Ti-Nb, Co
—Ti—Zn—Nb, Cu—Zr, Cu—Zr, Ni—
Those to which Ti or the like is added can also be used.

The binder used for the magnetic paint 10 may be a known thermoplastic resin, thermosetting resin, reactive resin, or the like which has been conventionally used as a binder for a magnetic recording medium. Those having an average molecular weight of 5,000 to 100,000 are preferred.

Examples of the thermoplastic resin include vinyl chloride,
Vinyl acetate, vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylate ester-acrylonitrile copolymer, acrylate ester vinyl chloride vinylidene chloride copolymer, vinyl chloride- Acrylonitrile copolymer,
Acrylate-acrylonitrile copolymer, acrylate vinylidene chloride copolymer, methacrylate vinylidene chloride copolymer, methacrylate vinyl chloride copolymer, methacrylate-ethylene copolymer, polyvinyl fluoride, Vinylidene chloride-acrylonitrile copolymer, acrylonitrile-butadiene copolymer, polyamide resin, polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose), styrene butadiene copolymer , Polyurethane resin, polyester resin, amino resin, synthetic rubber and the like.

Examples of the thermosetting resin include phenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, silicone resin, polyamine resin, urea formaldehyde resin and the like.

In addition, all of the above binders include pigments.
In order to improve dispersibility, -SM _ThreeM, -OSO
_ThreeM, -COOM, P = O (OM)_TwoPolar functional groups
It may be introduced. Here, M in each chemical formula is hydrogen
Atom or lithium, potassium, sodium, etc.
Potassium metal.

Further, as the polar functional group, -NR
_{1 R 2, -NR 1 R 2} R 3 + X - as the side chain type having an end group ^{_{of,> NR 1 R 2 + X}} - are those of the main chain type.
Here, R ₁ , R ₂ and R ₃ in each chemical formula are a hydrogen atom or a hydrocarbon group, and X ⁻ is a halogen element ion such as fluorine, chlorine, bromine or iodine or an inorganic or organic ion. In addition, there are polar functional groups such as —OH, —SH, —CN, and an epoxy group. The amount of these polar functional groups is 10 ^-1 to 10 ^-8 mol / g, preferably 10 ^-2
And 10 ^-6 mol / g.

The magnetic paint 10 can further contain a lubricant, non-magnetic reinforcing particles, and the like, if necessary.

Examples of the lubricant include graphite, molybdenum disulfide, tungsten disulfide, silicone oil, fatty acids having 10 to 22 carbon atoms, and fatty acids having 2 to 2 carbon atoms.
Fatty acid esters comprising up to 6 alcohols, terpene compounds, oligomers thereof, fluorine-based lubricants and the like.

The nonmagnetic reinforcing particles include aluminum oxide (α, β, γ), chromium oxide, silicon carbide, diamond, garnet, emery, boron nitride, titanium carbide, titanium carbide, and titanium oxide (rutile, anatase). Etc. The amount of the particles is desirably 20 parts by weight or less, preferably 10 parts by weight or less, more preferably 5 parts by weight or less based on 100 parts by weight of the ferromagnetic powder. The particles have a Mohs hardness of 4 or more, preferably 5 or more.
Above, more preferably 6 or more, specific gravity 2-6,
Preferably, it is in the range of 3 to 5, and the average primary particle size is 1.0.
μm or less, preferably 0.5 μm or less, more preferably 0.3 μm or less.

Solvents used for forming the magnetic paint 10 include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohol solvents such as methanol, ethanol, and propanol;
Methyl acetate, ethyl acetate, butyl acetate, propyl acetate,
Ester solvents such as ethyl lactate and ethylene glycol acetate, diethylene glycol dimethyl ether,
-Ethyl solvents such as ethoxyethanol, tetrahydrofuran and dioxane; aromatic hydrocarbon solvents such as benzene, toluene and xylene; and halogenated hydrocarbon solvents such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform and chlorobenzene. These are appropriately mixed and used.

These magnetic materials, binders, dispersants, lubricants, and the like are kneaded and dispersed in an organic solvent by a mixing device to form a magnetic paint 10.

As the mixing device used in the kneading step, there are conventionally known kneading devices such as a continuous twin-screw kneader, a continuous twin-screw kneader capable of multi-stage dilution, a kneader, a pressure kneader, a roll kneader and the like. The use of a kneader is possible, and there is no limitation. In the subsequent coating preparation step, any of a roll mill, a ball mill, a horizontal sand mill, a spike mill, a pin mill, a tower mill, a DCP, an agitator, a homogenizer, an ultrasonic disperser, and the like can be used in the dispersion step.

The magnetic coating material 10 is applied on the flexible non-magnetic support 9 such as a polyester film by the coating device 2 to form a magnetic coating film.

As shown in FIG. 5, the coating structure of the magnetic recording medium may be a multi-layer coating type medium in which the lower layer 11a and the upper layer 11b are coated on the nonmagnetic support 9 in this order, or may be a single layer. The lower layer 11a may be a magnetic layer, but if an effect of a thin upper layer is expected, a nonmagnetic layer is more preferable. Further, the back coat layer 12 is formed by coating as necessary. If necessary, three or more layers can be applied.
An abrasion-resistant film may be overcoated on the upper layer for the purpose of improving running durability, but the spacing loss must be minimized.

Non-magnetic pigments used as non-magnetic lower-layer pigments in the multi-layer coating include, for example, non-magnetic iron oxides such as α-Fe ₂ O ₃ , goethite, rutile-type titanium oxide, anatase-type titanium oxide, and tin oxide. , Tungsten oxide, silicon oxide, zinc oxide, chromium oxide, cerium oxide, titanium carbide, BN, α-alumina, β-alumina, γ-alumina, calcium sulfate, barium sulfate, molybdenum disulfide, magnesium carbonate, calcium carbonate, carbonic acid Barium, strontium carbonate, barium titanate, etc.,
These nonmagnetic pigments can be used alone or in combination of two or more.

The non-magnetic pigment may be doped with an appropriate amount of impurities according to the purpose. Al, S, and S may be used for the purpose of improving dispersibility, imparting conductivity, and improving color tone.
Surface treatment with compounds such as i, Ti, Sn, Sb, and Zr is also possible. The specific surface area of the nonmagnetic pigment is 5 to 100.
m ² / g, it is desirable that preferably 20~70m ² / g. When the specific surface area is in the above range, the lower layer is smoothed with the fine particles of the non-magnetic pigment, and as a result, the upper layer can be smoothed, so that the modulation noise characteristics are excellent and the influence of the spacing loss is reduced. It is possible to obtain a small number of magnetic recording media. If the specific surface area is larger than the above range, it becomes difficult to disperse in the coating material, and if the specific surface area is too small, the surface smoothness that can withstand high-density recording cannot be secured. The binder and solvent used in the nonmagnetic lower layer are the same as those used in the magnetic layer.

The coating method is not particularly limited, but it is preferable to apply each of the above-mentioned coatings in a multi-layered form on the non-magnetic support 9, and a die coater is mainly used for this. As the lip configuration of the die coater, a two-lip method, a three-lip method, a four-lip method, or the like is used. When the lower layer 11a and the magnetic layer (upper layer) 11b are formed on the non-magnetic support 9, a so-called wet-
There are a so-called wet-on-wet coating method, i.e., a wet multilayer coating method, in which a magnetic layer is overlaid on a lower layer in a wet state that has not been dried. It is preferable to perform simultaneous wet multilayer coating by a wet-on-wet multilayer coating method from the viewpoints of adhesiveness of upper and lower interfaces and productivity.

In this wet-on-wet multi-layer coating method, as shown in FIG. 6, a film-like support 9 fed from a supply roll is continuously run in a direction indicated by an arrow A in FIG. The coatings 10a and 10b for the lower layer 11a and the magnetic layer 11b are simultaneously applied on the support 9 by the extrusion coater 2 of the extrusion method.

The extruder coater 2 is provided with paint reservoirs 13a and 13b for accommodating the above-mentioned paints, and the paint 1 extruded from the paint reservoirs 13a and 13b.
0a and 10b are simultaneously superimposed on the support 9 in a wet-on-wet manner. In such a wet-on-wet simultaneous wet coating method, the lower layer 11
Magnetic paint 1 for upper magnetic layer 11b while a is wet
0b is applied, the surface of the lower layer 11a (that is, the upper
B), the surface properties of the upper layer 11b are improved, and the adhesion between the upper and lower layers 11a and 11b is improved. As a result, the magnetic recording medium satisfies the required performance as a magnetic recording medium that requires high output and low noise particularly for high-density recording, and film peeling is eliminated and film strength is improved. In addition, dropout can be reduced, and reliability is improved.

The upper and lower layers 11a and 11b formed by this wet-on-wet multi-layer coating method are mixed with components of a certain thickness except for a case where a clear boundary substantially exists. In some cases, the upper layer or the lower layer excluding such a boundary region may be an upper magnetic layer, a lower magnetic layer, or a lower nonmagnetic layer.

As described above, the magnetic recording medium in which the magnetic paint 10 is applied on the non-magnetic support 9 is
Pass through. During the passage of the magnetic recording medium, the magnetic paint 10 on the support 9 is dried and the magnetic powder in the magnetic paint 10 is efficiently oriented in one direction. At this time, the orientation device M1 sets the temperature and the amount or speed of the air in accordance with the magnetic recording medium passing therethrough. Therefore, the magnetic recording medium that has passed through the orientation device M1 can dry the magnetic paint 10 without causing the surface of the magnetic layer to be wavy or rough.

The magnetic recording medium is calendered in a calender device 7 after drying, and wound up in a coil shape in a winding device 8. Further, a back coat layer is applied to the magnetic recording medium on the opposite side of the multilayer coating layer. Thereafter, the magnetic recording medium is, for example, 8 m
It is cut into a tape shape by being cut into an m width, and housed in a cassette to form a tape cassette. Alternatively, the magnetic recording medium is punched out to a predetermined size after the calendering process, stored in a diskette, and becomes a magnetic disk medium.

According to the above embodiment, the dryer 4
Slit 4 of opening 4c arranged in magnet 3
Since uniform hot air is supplied from d to the entire length of the non-magnetic support 9 in the traveling direction A, it is possible to suppress the undulation of the magnetic paint 10, smooth the surface, and efficiently perform drying in a magnetic field. .

Further, since the dryer 4 has the adjusting mechanism 4a in which the temperature and the flow rate or the speed of the warm air are respectively adjusted, the magnetic paint 10 is prevented from waving due to the wind pressure, and the magnetic paint 10 Can be adjusted so that the powder is sufficiently dried while maintaining a high surface property, and the magnetic powder in the magnetic paint 10 is efficiently oriented. Therefore, the magnetic paint 10 can be sufficiently dried while maintaining a high level of surface properties, and the magnetic powder in the magnetic paint can be efficiently oriented, which improves the orientation and smoothes the surface. It is possible to manufacture the magnetic recording medium 20 which is compatible with the high-density recording.

Further, warm air is applied to the magnetic paint 1 of the non-magnetic support 9.
Openings 4c of the nozzles 4b of the dryer 4 are provided on the upper surface side where 0 is applied and on the lower surface side opposite thereto, and hot air is supplied to the non-magnetic support 9 from the slits 4d of the respective opening portions 4c. Therefore, the non-magnetic support 9 can be held in the magnet 3 without providing a guide roller or the like, and the distance between the magnet 3 and the non-magnetic support 9 is reduced to improve the efficiency of the magnetic field for orientation. can do.

Further, the slits 4d of the opening 4c are provided on both sides of the non-magnetic support 9, and the upper and lower slits 4d of the non-magnetic support 9 are arranged at equal intervals by shifting the positions by a fixed amount (D / 2). As a result, the balance of the force applied to the tape can be maintained, so that even if the tension is reduced, the tape can be prevented from fluttering and a good running state can be achieved. Thereby, the tension per unit width (N / m) of the nonmagnetic support can be reduced to 16 to 64 N / m. Further, since the tension can be reduced, the elongation of the tape caused by being pulled during the heating can be avoided.

The suction nozzle 5b and the solvent recovery device 5a are provided as a device for sucking and recovering the organic solvent evaporated from the magnetic paint 10 by the warm air,
The evaporated organic solvent is reliably separated and recovered, and the orientation device M
The steam exhausted from 1 can be harmless.

Further, in the manufacturing apparatus in which a plurality of orienting devices provided with a magnet for generating a magnetic field and a dryer for drying magnetic paint are proposed, the cross-sectional area of the outlet is small. When the running speed was increased, sufficient drying could not be performed. On the other hand, in the orientation device M1 of the present embodiment, the dryer 4
The opening 4c is provided in the entire magnet 3 so that the warm air can be applied to the non-magnetic support 9 in the entire length direction of the magnetic field by the magnet 3, and the time during which the warm air is blown becomes longer. Even if the traveling speed of the support 9 is increased, it is possible to sufficiently dry the support. In addition, since the drying efficiency is improved, the same drying effect as that of the conventional apparatus can be obtained even if the temperature of the hot air is lowered compared to the conventional apparatus.

[0069]

EXAMPLES The following experiments were conducted to confirm the effects of the present invention. That is, as shown in FIG. 1, in passing through a non-magnetic support coated with a magnetic paint to a magnetic recording medium manufacturing apparatus provided with an orientation device M1, orientation and drying are performed.
The magnitude of the applied magnetic field of the orientation device, the temperature of the hot air, and the speed of the hot air were changed, and the relationship between these and the magnetic recording medium to be manufactured was examined.

<Experiment 1> (Application of Magnetic Paint) Upper paint and lower paint were prepared with the following compositions. According to a conventional method, a pigment, a binder, an additive, and a solvent were mixed and kneaded by a continuous kneader, and then the upper coating was dispersed in a sand mill for 5 hours, and the lower coating was dispersed in a sand mill for 3 hours.

Upper layer coating composition : Fe-based metal ferromagnetic powder (average major axis length = 0.2 μm, needle ratio = 9, saturation magnetization = 130 Am ² / kg, coercive force = 135 kA / m) 100 parts by weight-poly 14 parts by weight of vinyl chloride resin (polymerization degree 150, containing 5 × 10 ⁻⁵ mol / g of sodium sulfonic acid salt as a polar functional group) ・ Polyester polyurethane resin (1 × 10 ^{−4 of} sodium sulfonic acid salt as a polar functional group) mol / g) 6 parts by weight ・ Al ₂ O ₃ (primary particle size 0.09 μm, dispersed in a solvent to form a slurry, mixed with other composition in a slurry state) 5 parts by weight ・ Stearic acid 1 1 part by weight of heptyl stearate 150 parts by weight of methyl ethyl ketone 150 parts by weight of cyclohexanone Lower layer paint composition α-Fe ₂ O ₃ (specific surface area = 40 m ² / g, needle Shape ratio = 8) 100 parts by weight Polyvinyl chloride resin (degree of polymerization 150, containing 5 × 10 ⁻⁵ mol / g of sodium sulfonic acid salt as a polar functional group) 9 parts by weight Polyester polyurethane resin (as a polar functional group) sodium sulfonate 1 × 10 ^-4 mol / g including) 9 parts by weight stearic acid 1 parts by weight heptyl stearate 1 part by weight Methyl ethyl ketone 105 parts cyclohexanone 105 parts by weight

(Application of Magnetic Paint) 4 parts by weight of polyisocyanate was added to the obtained upper layer paint, and 2 parts by weight of polyisocyanate was added to the lower layer paint, and the upper and lower layer paints were applied using a 4-lip type die coater. Four polyester films as support (thickness: 6.0 μm, surface roughness: good roughness surface = 5.5 nm, bad roughness surface = 7.0 nm)
It was overcoated on top. Here, the coating thickness of the upper layer and the lower layer is 2.0 μm so that the upper layer becomes 0.15 μm after drying.
It was set to be μm. The coating speed is 25 per minute.
0 m.

(Drying and Orientation of Magnetic Paint) Four non-magnetic supports 9 to which the above-described magnetic paint 10 is applied are prepared. These non-magnetic supports 9 are provided with the orienting device M
1 and the magnetic paint was dried and the magnetic powder in the magnetic paint was oriented. At this time, the orientation device M
1 The temperature of the hot air is 80 ° C, and the speed of the hot air is 10 m / s
In addition, the magnitude of the applied magnetic field of the orientation device M1 is 0.64 MA /
m.

The length of the short side of the slit hole of the nozzle (corresponding to d1 in FIG. 3B) is set to 1 mm (Example 1) when passing through the first support, and passing through the second support. The length was set to 3 mm (Example 2) when passing through, and 5 mm (Example 3) when passing through the third support, and 8 mm (Example 4) when passing through the fourth support.

(Measurement) On the magnetic recording medium manufactured as described above, a back coating is applied to the surface opposite to the surface on which the upper coating and the lower coating have been applied. Then, the magnetic recording medium is subjected to a calendar process and a curing process,
It is cut into 8 mm width and taped.

The surface roughness, the degree of orientation, and the output (electromagnetic conversion characteristics) of the four magnetic tapes thus completed were measured, and the relationship between these and the magnitude of the hot air flow was examined. The amount of hot air was 400 m ^{3 in} the case of the first embodiment.
/ H, and the 600 meters ³ / h (hour 600 meters ³⁾ in the case of Example 2, and in the case of Example 3 1000 m ³
/ H, and in the case of Example 4, it is 1600 m ³ / h. Table 1 shows the results. The surface roughness was measured with a non-contact optical surface roughness meter (manufactured by ZYGO), and the magnetic characteristics were measured using a vibrating sample magnetometer (manufactured by Toei Kogyo) and the external magnetic field was set to 0.8.
It was measured at MA / m (10 kOe). The degree of orientation was determined by the squareness ratio (residual magnetic flux density / saturated magnetic flux density). The output was modified from the Sony Hi-8 deck, and the wavelength λ = 0.
It was measured at 5 μm. The output was standardized by setting a commercially available Hi-8MP tape to 0 dB.

[0077]

[Table 1]

From the results shown in Table 1, the length of the short side of the slit hole of the nozzle affects the surface properties and orientation of the manufactured magnetic recording medium, and the length of the short side of the slit hole of the nozzle is short. That is, it was found that the squareness ratio and the output decreased as the air volume decreased.

<Experiment 2> Four nonmagnetic supports 9 coated with the same magnetic paint as the nonmagnetic support 9 used in Experiment 1 are prepared. Then, the nonmagnetic support 9 was sent out so as to pass through the orientation device M1 used in Experiment 1, and the drying of the magnetic paint and the orientation of the magnetic powder in the magnetic paint were performed. On this occasion,
The magnitude of the applied magnetic field of the orientation device M1 was set to 0.64 MA / m, the temperature of the hot air was set to 80 ° C., and the length of the short side of the slit hole of the nozzle was set to 5 mm.

Then, the wind speed of the warm air of the orientation device M1 is set to 1
5 m / s (Example 5) when passing through the second support, 10 m / s when passing through the second support
/ S (Example 6), 15 m / s (Example 7) when passing through the third support, and 20 m / s (Example 8) when passing through the fourth support.

(Measurement) A back coating was applied to the magnetic recording medium manufactured as described above, as in Experiment 1.
It is subjected to a calendering treatment and a curing treatment, cut into a width of 8 mm, and taped.

The surface roughness, the degree of orientation, and the magnitude of the output of the four magnetic tapes thus completed were measured in the same manner as in Experiment 1, and the relationship between these and the wind speed of the warm air was examined. The air volume of the warm air also increases or decreases according to the wind speed of the warm air, and the air volume of the warm air is 500 m ³ / h in the case of the fifth embodiment, and 1000 m ³ / h in the case of the sixth embodiment. Is 1500 m ³ / h, and in the case of Example 8, it is 2000 m ³ / h. Table 2 shows the results.

[0083]

[Table 2]

From the results shown in Table 2, it can be seen that increasing the wind speed of the warm air deteriorates the surface roughness and lowers the output. Then, it was found that when the wind speed of the warm air was too high, 20 m / s, the surface roughness deteriorated and the output also decreased.

Therefore, as described above, the speed of the warm air is set to 1
It is desirable to set the range to 15 m / s. If the wind speed is less than 1 m / s, the effect of hot air drying cannot be sufficiently obtained, and after the magnetic powder in the magnetic paint 10 repels and moves after coming out of the magnet 3, the orientation may be lost. .

<Experiment 3> Two non-magnetic supports 9 coated with the same magnetic paint 10 as those used in Experiment 1 were prepared. One of the supports 9 was as shown in FIGS. 2 and 3A. The position of the slit 4d of the opening 4c is vertically
Alignment devices M1 alternately arranged at equal intervals in the openings 4c
(Example 9), and the other support 9 is
The slits 4d of c are passed through the orienting device M2 (not shown) at the same position in the upper and lower openings 4c of the dryer 4 (Example 10), and the respective orienting devices M1 or M
In step 2, the magnetic paint was dried and the magnetic powder in the magnetic paint was oriented. In each case, the magnitude of the applied magnetic field of the orientation device M1 was 0.64 MA / m, and the temperature of the hot air was 80
° C, the wind speed was set to 10 m / sec, and the length of the short side of the slit hole 4d was set to 5 mm.

(Measurement) The back coating was applied to the magnetic recording medium manufactured as described above, as in Experiment 1.
It is subjected to a calendering treatment and a curing treatment, cut into a width of 8 mm, and taped.

The surface roughness, the degree of orientation, and the magnitude of the output of the two magnetic tapes thus completed were measured in the same manner as in Experiment 1, and the relationship between these and the arrangement of the slit holes was examined. Table 3 shows the results. In addition, Table 3 adds the items of running stability. The case where the tape is maintained in a good running state is indicated by a circle, and the case where the tape cannot be maintained due to fluttering or the like cannot be maintained is indicated by a cross.

[0089]

[Table 3]

From the results shown in Table 4, it can be seen that Example 9 in which the slits 4d are provided alternately at equal intervals improves the surface roughness, the squareness ratio and the output. From this, it can be seen that by alternately providing the slits 4d at equal intervals, the balance of the force applied to the support is improved, and the characteristics of the magnetic recording medium can be improved.

As is evident from the results of the above experiment, the orientation device M1 incorporating the dryer 4 for supplying warm air to the inside of the magnet 3 through which the tape of the nonmagnetic support 9 passes is installed, and it is necessary for orientation. While securing the magnetic field
By alternately providing slits 4d at equal intervals and adjusting the wind speed of the warm air of the orientation device M1, a magnetic recording medium compatible with high-density recording can be manufactured.

The amount of warm air is 600 m ³ / h to 20 m ³ / h.
It can be seen that setting to 00 m ³ / h is preferable because various characteristics become good. And especially, the air volume is 1000 m ³ /
It can be seen that when the value is about h, the characteristics become very good.

The present invention is not limited to the above-described embodiment, but may take various other configurations without departing from the gist of the present invention.

[0094]

According to the present invention described above, the magnetic paint on the non-magnetic support is dried and oriented when passing through an orientation device adapted to adjust the temperature and the amount or velocity of the hot air. With this configuration, drying is performed while maintaining high surface properties, and both improvement of orientation and smoothing of the surface can be achieved.

Further, according to the present invention, the positions of the outlets of the hot air are regularly shifted at equal intervals on one side and the other side of the nonmagnetic support. Thus, the influence of the warm air on the running state can be extremely reduced, and the balance of the force applied to the non-magnetic support can be maintained. Thereby, the tension (N / m) per unit width of the nonmagnetic support in the traveling direction of the nonmagnetic support is 1
The range is 6 to 64 N / m, and the running state of the non-magnetic support can be favorably maintained even with such a low tension. Therefore, by setting the tension low, the elongation of the non-magnetic support in the traveling direction is avoided.

Therefore, the magnetic recording medium manufactured according to the present invention is dried while maintaining a high level of surface properties, thereby achieving both improvement of the orientation and smoothing of the surface, and can cope with high-density recording. .

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of a magnetic recording medium manufacturing apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram of an orientation device.

FIG. 3A is a cross-sectional view of a main part of the orientation device of FIG. 2; B is an enlarged view of a part of FIG. 3A.

FIG. 4 is a perspective view of a main part of a dryer on the lower side of the orientation device of FIG. 2;

FIG. 5 is a cross-sectional view of a main part for explaining a coating film configuration of a magnetic recording medium.

FIG. 6 is a schematic diagram of a coating device that applies a magnetic paint.

[Explanation of symbols]

1 unwinding device, 2 coating device, 3 magnet, 4
Dryer, 5 Solvent suction device, 6 Drying device, 7
Calendar device, 8 take-up device, 9 non-magnetic support, 10 magnetic paint, 20 magnetic recording medium, M1, M2
Orientation device

Claims (4)

[Claims] 1. An apparatus for manufacturing a magnetic recording medium for drying a magnetic paint in a magnetic paint applied on a non-magnetic support while orienting the magnetic powder in a certain direction, wherein the magnetic powder is oriented. A dryer having a magnetic field generator and having an opening for supplying hot air for drying the magnetic paint, and a dryer having an adjusting mechanism adapted to adjust the temperature and the amount or speed of the hot air, respectively. The opening portion of the nozzle is disposed on both sides of the non-magnetic support in the magnetic field generator so that the hot air is supplied over the entire length of the non-magnetic support in the traveling direction. In the openings of the nozzles arranged on both sides of the non-magnetic support, the positions of the outlets of the warm air are regularly spaced on one side and the other side of the non-magnetic support. A staggered relationship And made by the tension per unit width of the non-magnetic support in the travel direction of the nonmagnetic support passing through the apparatus (N / m) is 1
An apparatus for producing a magnetic recording medium, wherein the magnetic recording medium is set within a range of 6 to 64 N / m. 2. The magnetic recording medium manufacturing apparatus according to claim 1, wherein an opening width of the opening of the nozzle in the traveling direction is set to 1 to 8 mm. 3. An interval between the openings of the nozzle is 30.
2. The apparatus for manufacturing a magnetic recording medium according to claim 1, wherein the distance is set to 60 mm. 4. The flow rate of the hot air is 600 to 200 per hour.
2. The magnetic recording medium manufacturing apparatus according to claim 1, wherein the magnetic recording medium is set to 0 m ³ .