KR950012367B1 - A method of manufacturing magnetic recording medium - Google Patents

Abstract

installing a pre-orientation processing unit for first orientating a magnetic material formed on a base film and a main-orientation processing unit for finally orientating the magnetic material; forming a plurality of air induction devices on the front and rear of an orientation magnet; and applying tension on the base film to whereby achieve a stable orientation.

Description

Magnetic recording medium manufacturing method

1 is a view illustrating a conventional alignment method

Figure 1a is an illustration of a dual orientation method.

Figure 1b is a diagram illustrating a multiple orientation method.

2 is a diagram illustrating the alignment process of the present invention.

* Explanation of symbols for main parts of the drawings

1: coating part 2: air suction device

3: orientation magnet 4: soft magnetic material

5: auxiliary plate 6: dryer

The present invention relates to a method of manufacturing a magnetic recording medium. In particular, the magnetic recording excellent in the electronic conversion characteristics due to the improved orientation by preventing the degradation of the orientation of the magnetic coating film that may be caused by hot air and mechanical vibration in the drying process of the magnetic recording medium manufacturing process A method for producing a medium.

In general, a process of manufacturing a coated magnetic recording medium is performed by using a magnetic coating composed of a fine magnetic powder on a base film made of a polyester film and a magnetic paint composed of a binder, a lubricant, an abrasive, and carbon black. After coating, the magnetic layer of the magnetic layer is oriented in one direction, the magnetic layer is cured through a drying process and an ironing process, and then cut into a predetermined width to form a magnetic recording medium.

The magnetic recording medium produced by such a process may be used by selectively selecting various raw materials used in the magnetic recording medium as having excellent characteristics in order to improve the characteristics of the magnetic recording medium according to the rapid progress of high quality and high density, or manufacturing of the magnetic recording medium. Different methods have been proposed for producing a magnetic recording medium having excellent characteristics.

In more detail, a conventional method of manufacturing a magnetic recording medium is obtained by applying a magnetic coating made of magnetic powder, a binder, a lubricant, an abrasive, carbon black, or the like with an applicator such as a gravure coater or reverse coater. Afterwards, the orientation is made by using a counter opposing magnet.

Here, the principle of orienting the magnetic material by using the repulsive opposing magnet is that the N poles of the two magnets face each other with the base film in between by using the two magnets, so that the magnets are in the direction of the flux by the repulsive force of the two magnets. The principle that the magnetic material is oriented is applied, where the strength of the orientation magnet is generally 3 to 5 times stronger than the magnetic force of the magnetic material.

The repulsive opposing magnet is a permanent magnet or a magnetic field generated by the internal current of the solenoid by applying a current to the solenoid as a magnet. When the magnetic substance of the coating layer is oriented using the solenoid, the intensity of 1000Oe to 5000Oe is used. The magnetic field must be hung, and the magnetic field is mainly oriented by using permanent magnets, which are simple to install and require little maintenance cost, because of the disadvantage of generating a lot of power and sparking or difficulty in installing the magnetic field.

On the other hand, in order to improve the characteristics of the magnetic recording medium, a method of increasing the filling rate of the magnetic material by forming a magnetic coating film using a small magnetic material and a large specific surface area has been attempted, but in this case, a magnetic paint containing a magnetic material made of ultra fine particles After the coating on the base film and oriented, the effect of the interaction between the magnetic particles increases, so that the orientation of the particles is lowered, thereby reducing the electron conversion characteristics.

In order to solve the problem of deterioration of orientation due to the interaction between particles, a method of increasing the resilience by increasing the repulsive force between the alignment magnets by installing a resilient counter magnet at a narrow interval is also attempted. Passing the base film coated with the magnetic paint between the opposing magnets causes magnetization of each magnetic particle, causing the orientation to be disturbed due to the interaction between the particles, and when the base film coated with the magnetic paint is transferred, By not being uniformly affected by flux, the surface of the coating film is degraded or the coating film of the applied base film is easily attached to the alignment magnet, which not only causes scratches (scratch) on the magnetic coating film but also magnetic coating on the base film. There may be parts which are not applied properly The.

Alternatively, in order to improve productivity when manufacturing a magnetic recording medium, a method of applying a magnetic paint by allowing the base film to pass through the applicator at a high speed is used, but in this case, the time to pass the repellent orientation magnet is shortened. Because of this, there was a disadvantage in that sufficient orientation cannot be achieved.

As described above, after the magnetic coating is applied on the base film during the manufacturing process of the magnetic recording medium, the orientation time is increased while the strength of the orientation magnet is increased to increase the orientation by improving the disadvantages of some methods used as the orientation method. As one of the methods, as shown in FIGS. 1a and b, a double or multi-orientation method is provided in which a plurality of opposing magnets are installed so that the N poles of two magnets face each other with a base film interposed therebetween. .

However, when double-orienting the magnetic body of the magnetic coating film, the orientation is improved, but the surface property of the coating film is poor, and when the drying is performed under the alignment of several alignment magnets, the orientation is better, but the drying hot air is irregular or hot air from the upper and lower parts of the dryer. Due to the hot air is sprayed by the floating method that the film is floated in the air and dried, if the thickness of the polyester film is thin in both multi-orientation or double-orientation, the coated film is dried up and down in the dryer before it is completely dried. By vibrating, the coating film sticks to the alignment magnets, causing scratches and no coating to occur on the coating film. In addition, in order to solve such a problem, a method of increasing the tension in the winding portion of the film is attempted, but this also causes a problem that longitudinal wrinkles occur in the applied film as the tension increases.

The present invention is to improve the above-mentioned drawbacks of the conventional orientation treatment unit and the main orientation treatment unit in the dryer inlet and the air suction device in the front and rear of the alignment magnet to form a film coated with magnetic paint when passing through the alignment magnet The stable orientation is achieved and the auxiliary plate is attached to the alignment magnet so that the influence of the magnetic force of the alignment magnet can be uniformly applied to the magnetic coating film.

First, in order to explain the manufacturing method of the magnetic recording medium of the present invention in detail, the construction and the manufacturing method of the manufacturing apparatus will be described with reference to FIG. 2 showing the orientation process explanatory diagram of the present invention. On the base film (7) coated with a soft magnetic rod having excellent permeability or a soft magnetic material (4) having a carbon content of 0.02% to 0.2%, and a magnetic coating applied to the base film (7) under the base film (7). The alignment magnets 3 are installed so that the magnetic bodies of the magnets can be oriented.

This orientation magnet (3) is one of the corners at an angle or obliquely rounded permanent magnets so that the magnetic flux is concentrated only at the end of the permanent magnet so that the magnetic flux of the permanent magnet flows to the soft magnetic material (4) above. The magnetic material of the magnetic paint applied to the film 7 is erected perpendicularly to the film on the permanent magnet, and after the base film passes the end of the alignment magnet 3, the magnetic lines are weakly radiated from the oblique portions of the permanent magnet. It serves to be oriented in the advancing direction of the coating film.

In addition, the strength of the orientation magnet (3) is about 1 to 4 times the strength of the magnetic force of the magnetic material is used. When the strength of the orientation magnet is less than 1 times that of the magnetic material, the orientation of the magnetic material is not achieved. If the strength of the permanent magnet is 4 times or more, the orientation may be good, but the surface of the coating is worse due to the interaction between particles. Therefore, 1.5 times to 3 times as long as the permanent magnet having a strength of 1500 to 3000 gauss (G) is suitable.

The soft magnetic material 4 on the alignment magnet 3 is preferably one having a magnetic permeability (μ) of 1000 or more and 10,000 or less, and soft iron having a carbon content of 0.02% to 0.2% or less when an iron rod is used.

If it is less than 0.02%, the permeability is high, but it is easy to rust, and if it is more than 0.02%, the permeability is not preferable.

In addition, the main alignment treatment apparatus of the present invention is installed at the inlet of the dryer 6, as shown in the portion B of FIG. The distance between them is 5 mm to 30 mm or less, preferably 8 to 10 mm. When the distance between the magnets is 5mm or less, the film coated with the magnetic paint is easy to stick to the magnets, and when the thickness of the magnets is 30mm or more, the strength of the orientation magnet is weakened, so that the orientation is not completed. In addition, the strength of the alignment magnet 3 for main alignment treatment may be 2,000 to 5,000 gauss (G) permanent magnets, which are about 1 to 5 times preferably 1 to 4 times the strength of the permanent magnet for full orientation treatment. .

In the main orientation treatment part (B), subsidiary plates made of soft magnetic material having a width equal to the width of the base film at the front and rear of the orientation magnets 3 and below 100 or less than 10,000, or a magnetic plate having a carbon content of 0.02% to 0.2% (5) is attached to the alignment magnet (3), the angle between the auxiliary plate (5) and the alignment magnet (3) within 5 ° to 45 °, the thickness is within 2mm to 10mm, and the length is within 10cm to 50cm Be sure to

If the angle of the auxiliary plate 5 made of soft magnetic material or iron plate with the alignment magnet 3 is 45 ° or more, the auxiliary plate vibrates under the influence of the magnetic lines of the alignment magnet, and the influence of the lines of magnetic force falls on the base film and the film vibrates weakly. As a result, the orientation is lowered and the surface of the coating film is deteriorated. When it is 5 degrees or less, there is no big effect in improving the orientation and surface property of a magnetic coating film.

The material of the auxiliary plate made of soft magnetic material is made of silicon steel sheet or high magnetic permeability soft magnetic metal alloy. Fe-Co-Ni alloy Co-Ni-Mg alloy can be used as soft magnetic metal alloy. In addition, a plurality of air suction devices in front and rear of the permanent magnets for orientation in order to achieve a stable orientation by applying tension to the polyester film at the alignment portion during the alignment treatment in each alignment treatment unit to eliminate the vibration during the alignment treatment (2) Install). The air suction device 2 has a roll or polygonal shape, and a hole having a surface of about 0.1 mm to 1 mm is formed.

The air intake device 2 is designed to suck the outside air into the inside through an outside hole by applying a vacuum to the inside, and the outside material of the air intake device 2 is made of rubber having excellent elasticity and the inside vacuum The pressure is 100 to 1000 mmH ₂ O, preferably 600 to 1000 mmH ₂ O.

100mmH ₂ O or less when the air intake device (2) the base film (7) above, and to this scratch occurs on the back surface of the base film with a magnetic paint is applied with a developing slipping on the air intake (2) 2000mmH ₂ O When the film is made larger, the magnetic paint-coated film is strongly sucked, so that a mark such as a hole is formed on the surface of the air intake device 2 on the back surface of the coating film, and the surface of the coating film is deteriorated.

In more detail the orientation method of the magnetic coating film in the manufacture of the magnetic recording medium of the present invention is carried out a pre-orientation treatment (Preorientation) and a main orientation (Main Orientation), and a plurality of front and rear permanent magnets used in the orientation Attach the air intake device so that the base film coated with the magnetic paint passes in contact with the air intake device and align it with the orientation magnet. As a pre-orientation treatment method, it is about 1 to 4 times higher than the magnetic body magnetic force of the magnetic paint. Permanent magnets and soft magnetic rods are installed on one permanent magnet with a high coercive force and a permeable soft magnetic bar or carbon bar with a carbon content of 0.02% to 0.2% on one permanent magnet that is angled or obliquely rounded. When the polyester film coated with magnetic paint passes through, the lines of magnetic force of the permanent magnet are mainly directed to the soft magnetic material on the permanent magnet. Since the effect of permanent magnets on the magnetic film is gradually weakened from passing through the permanent magnet and passing through the permanent magnet, the magnetic material on the magnetic film of the polyester film coated with the magnetic paint stands on the polyester film only when it passes over the permanent magnet. After passing through, the influence of the lines of magnetic force on the magnetic coating is gradually weakened so that the magnetic body is oriented in the traveling direction of the polyester film.

In addition, the main orientation treatment method faced each other with iron plates or soft magnetic materials with excellent permeability of carbon content of 0.02 to 0.2% in order to perfectly orient the magnetic material of the pre-orientation-treated magnetic coating film. Attached above and below the entrance and exit of the conventional permanent magnet for alignment, and by attaching a plurality of air suction devices to the front and rear of the permanent magnet, the pre-orientated polyester film can be used for the alignment permanent magnets facing the same pole. As the two poles of the alignment magnet pass through, the magnetic force lines of the permanent magnet are diverged from the inlet and outlet of the two alignment magnets, and the magnetic material of the magnetic film is reoriented, and the magnetic permeability of the alignment magnets is excellent. Orientation of the coating film by mechanical vibrations from the outside of the alignment magnet and divergence of magnetic force lines by the iron plate or soft magnetic material From outside and prevent the orientation magnet that the surface properties are degraded by the action the line of magnetic force of the permanent magnet to improve the surface of the orientation film and. In addition, when the alignment process is carried out by attaching a plurality of air suction devices before and after the alignment magnet, the polyester film is passed through the alignment magnet while the rear surface of the base film coated with the magnetic paint is attached to the air suction device. The local tension is imparted to the film at the alignment site without the shaking of the film due to hot air or mechanical vibration, resulting in a stable alignment treatment.

Example 1

The composition of the magnetic coating composition for carrying out the present invention is as follows.

Co containing r-Fe ₂ O ₃ 100g

8g polyurethane resin

15 g of vinyl chloride vinyl acetate copolymers

1.2 g butyl stearate

0.8 g stearic acid

5 g of carbon black

5 g of abrasive (0.4 μm α-Al ₂ O ₃ )

Methyl ethyl ketone 100g

Toluene 100g

100 g of cyclohexanone

Co-containing r-Fe ₂ O ₃ in the above composition has an average particle diameter of 0.19 μm, a BET of 45, an acicular ratio of 8.5 / 1, and a coercive force of 800Oe.

In the process of orienting the magnetic material using the magnetic coating, first, the magnetic coating composition is dispersed for about 20 hours using a high speed disperser and then filtered with a filter to prepare a magnetic coating.

Second, after applying the prepared magnetic coating to a 15㎛ thick base film at a speed of 300 ~ 500m / min per minute with a thickness of 4.5㎛ and the orientation pre-treatment part where the orientation magnet of 2000G intensity and soft iron with a carbon content of several percent or less The base film coated with the magnetic paint passes through the gap between the alignment magnet and 12mm.

Third, at the inlet of the dryer, 4500G orthogonal magnets facing each other are installed so as to face each other so as to maintain a gap of 12 mm, and the gaps are oriented through a base film coated with magnetic paint.

Fourth, the surface of the magnetic layer is then processed by a calender roll after drying with a drying hot air of 100 to 1000 m / min at a temperature of 80 to 110 ° C.

Fifth, after curing for 2 days at a temperature of 60 ℃ and cut to 12.65mm to prepare a magnetic tape.

In the above-mentioned manufacturing process, the silicon steel plate having excellent permeability is attached to the auxiliary plate before, after, and under the alignment magnet of the main alignment treatment unit to perform alignment treatment, and rubber air is formed on the front and rear surfaces of the alignment pretreatment unit and the main alignment treatment unit. A suction roll was disposed to give a local tension to the base film to which the magnetic paint was applied so that the alignment treatment was performed in a flat state of the film.

Here, the internal pressure of the air suction roll was 700 mmH ₂ O.

Example 2

In the same magnetic coating composition as in Example 1, MnZnFerrite is used as a soft magnetic material manufactured by the same process and has excellent permeability instead of the soft iron rod in the orientation pretreatment part, and the pressure of the air suction roll is changed to 725 mmH ₂ O, Change the strength of the orientation magnet in the main alignment treatment unit to maintain 6000G, and use a soft iron plate with excellent permeability as an auxiliary plate instead of the silicon steel plate attached to the main alignment treatment unit.

Example 3

Prepared by the same composition as in Example 1 and using a permalloy of 75% Ni as a soft magnetic material in the orientation pretreatment unit, the pressure of the air suction roll to 725mmH ₂ O, the orientation of the alignment magnet The strength is 5000G, and Permalloy of 75% Ni is used as the auxiliary plate of the main alignment treatment part.

Example 4

The same composition as in Example 1 was prepared in the same process, and 75% Ni permalloy was used as the soft magnetic material in the orientation pretreatment unit, and the pressure of the air suction roll was 725 mmH ₂ O. The strength is set to 3000G, and a silicon steel sheet is used as an auxiliary plate of the main alignment treatment unit.

[Comparative Example]

As a comparative example of the prior art for comparison with the present invention, there is no orientation pretreatment part, a magnet having a strength of 4000 G as the main orientation treatment part, no auxiliary plate in the main orientation treatment part, and no air suction roll is used.

The following items were compared and evaluated for the characteristics of the magnetic recording media produced by the different manufacturing processes as described above.

1) Magnetic property: It is measured by magnetization (Vibrating Sample Magnetometer). As the result of measurement, the bigger magnetic property value of Br, O.R, S.R, the better recording medium and better electron conversion.

2) Surface Roughness: The surface roughness of the magnetic recording medium is measured by using SE-3H, a two-dimensional surface roughness measuring instrument of Kosaka Institute of Japan, and the center line average roughness (Ra) is specified. The smaller the surface roughness value Ra, the smoother the surface of the recording medium and the better the electron conversion characteristic.

3) RF output: A method of evaluating the characteristics of electronic conversion that affects gap loss and output fluctuation after making magnetic recording media. Using an oscilloscope, the relative value is obtained by comparing with the standard tape. The larger the RF output value, the better the signal output characteristic of the magnetic recording medium.

4) Video S / N and Color S / N: Measured and recorded using the HR-2200 VTR manufactured by Victor Co., Ltd. in Japan. Excellent and clear, the bigger the color S / N the better the color.

The comparative measurement results for the above evaluation items are as follows.

From the above results, the present invention sets the permanent magnet strength in the orientation pretreatment unit to about 2000 to 3000 gauss and installs a soft iron rod, soft magnetic manganese zinc ferrite or permalloy alloy as a soft magnetic material on the permanent magnet, and in the main orientation treatment unit Increasing the strength of the magnet and attaching a silicon steel plate or a soft iron plate or a Permalloy alloy plate with carbon content of 0.02 to 0.2% as an auxiliary plate, magnetic properties, It can be seen that the surface roughness and the electron conversion characteristics are excellent.

As described above, the present invention divides the alignment process into a pre-orientation processing unit and a main alignment processing unit, and then, in the pre-orientation, the magnetic body of the magnetic coating film is oriented in the traveling direction of the film, and then the main orientation processing unit Aligning with strong magnetic field at, and aligning soft iron rod or soft magnetic material with excellent permeability on the orientation magnet in the orientation pretreatment part, and aligning the orientation, and aligning with soft iron plate or auxiliary plate made of high permeability soft magnetic material The leakage magnetic flux of the magnet flows to the auxiliary plate to improve the surface of the magnetic coating film during the alignment process, and air suction rolls are installed before and after the alignment unit and the main alignment magnet to prevent the vibration of the film during the alignment process and to prevent the vibration of the film. Prevents the film from giving a local tension to perform a stable alignment treatment.

Claims (11)

In the manufacturing process of the magnetic recording medium, the orientation process is performed by aligning two or more times by providing a pre-orientation processing unit which primarily aligns the magnetic material of the magnetic coating film formed on the base film and a main orientation processing unit which finally orients the inlet of the dryer. A method of manufacturing a magnetic recording medium, characterized in that the magnet is oriented in a stable state and a plurality of air suction devices are formed to impart tension to the base film to achieve stable orientation. The method of manufacturing a magnetic recording medium according to claim 1, wherein a soft iron rod or a soft magnetic material is disposed on the alignment magnet and the alignment magnet in the prealignment processing unit. 2. The method of manufacturing a magnetic recording medium according to claim 1, wherein the upper and lower sides of the main alignment processing unit are formed of a soft iron plate smaller than the width of the orientation magnet or a metal plate made of a high permeability metal soft magnetic material as an auxiliary plate. . The method of manufacturing a magnetic recording medium according to claim 1, wherein a plurality of air suction devices are provided before and after the alignment magnet. The method of claim 1, wherein the air intake apparatus is a magnetic recording medium manufacturing method characterized in that the internal pressure of 100mmH ₂ O to 200mmH ₂ O. The method of manufacturing a magnetic recording medium according to claim 2, wherein the soft magnetic material is made of a soft magnetic ferrite such as MnZn Ferrite or a metal soft magnetic material such as a perm alloy. The method of manufacturing a magnetic recording medium according to claim 2, wherein the soft magnetic material has a magnetic permeability in the range of 1000 to 10,000 or less. The method of manufacturing a magnetic recording medium according to claim 2 or 3, wherein the soft iron rod and the soft iron plate have a carbon content in the range of 0.02% to 0.2%. 4. The method of manufacturing a magnetic recording medium according to claim 3, wherein a metal plate having a thickness of 0.1 to 10 mm is used as the metal soft magnetic material. 4. The method of manufacturing a magnetic recording medium according to claim 3, wherein the auxiliary plate is formed to be inclined at 5 to 45 degrees with respect to the alignment magnet. The method of manufacturing a magnetic recording medium according to claim 1 or 4, wherein the air suction device uses a plurality of holes formed in the surface of the cylinder in a cylindrical shape or a polygonal shape.