KR0142901B1 - Method of manufacturing magnetic recording medium - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetic recording medium capable of improving the magnetic properties, running properties, and durability of a magnetic tape by controlling curing conditions in the manufacture of an application type magnetic recording medium. A method of manufacturing a magnetic recording medium, comprising the steps of: preparing a magnetic layer by applying the magnetic paint to a film for magnetic recording medium and drying the same, wherein the magnetic layer is at a temperature of 50 ° C-70 ° C and a relative humidity of 40 ° C. It further comprises the step of curing at less than%.

Description

Manufacture of Magnetic Recording Media

The present invention provides a magnetic recording capable of improving the magnetic properties, runability and durability of the coating-coated magnetic tape by appropriately adjusting the curing conditions of the applied magnetic layer when the magnetic coating is applied to the film for the magnetic recording medium to prepare the magnetic recording. A method for producing a medium.

Magnetic recording media such as magnetic tapes and magnetic disks are manufactured by dispersing a magnetic material, a resin, a curing agent, a solvent, a dispersant, and other additives to form a magnetic coating film by coating and drying the same on a substrate, and in the audio, video, and computer fields. It is widely used on the back.

Since the magnetic recording medium is used in contact with the magnetic head, in addition to the magnetic characteristics, surface smoothness is required to improve the running property, and durability is required to enable repeated recording and reproducing.

Generally, in order to reduce noise in a magnetic recording medium such as an audio tape or a video tape, iron oxides such as γ-Fe ₂ O ₃ , Co-γ-Fe ₂ O ₃ , α-Fe, and the like are applied to a magnetic paint to be applied to the magnetic recording medium. And ferromagnetic powder. However, when the magnetic powder is made into fine particles in this way, there is a problem in that the wear resistance of the magnetic layer containing the same is lowered and the durability of the magnetic recording medium is also lowered. This problem can be reduced by appropriately adjusting the curing temperature, but spacing loss occurs due to wrinkles of the coating film that is hardened at too high temperature, resulting in poor regeneration output, and hardening at too low temperature. The durability becomes unstable.

The durability of the magnetic recording medium is also affected by humidity, but when the humidity is high, the ester in the polymer reacts with water to generate a low molecular weight molecule having a molecular weight of about 20,000, which causes a decrease in durability.

Accordingly, in view of the above problems, the present invention provides a method of manufacturing a magnetic recording medium capable of preventing reduction in the reproduction output of a magnetic recording medium coated with a magnetic paint and improving runability and durability by adjusting curing conditions. The purpose.

That is, the manufacturing method of the present invention includes the steps of preparing a magnetic paint comprising a magnetic material, a dispersant and a curing agent, and applying the magnetic paint to a film for magnetic recording media and drying to form a magnetic layer. In the manufacturing method, characterized in that it further comprises the step of curing the magnetic layer at a temperature of 50 ℃-70 ℃ and relative humidity 40% or less.

The manufacturing method of the present invention is to improve the magnetic properties, runability and durability by applying a magnetic paint and drying to remove the solvent, and then select the curing conditions within a certain temperature and relative humidity range.

When the curing temperature is lower than 50 ℃ hardening is not made well, the interval loss occurs only higher than 70 ℃, when the relative humidity is higher than 40% during curing, a low molecular weight by-product is produced.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples.

Example 1

α-Fe magnetic material: 100 parts by weight

(BET: 60㎡ / g, Coercive force: 1450 Oe)

Vinyl chloride vinyl acetate copolymer resin: 12.5 parts by weight

Polyurethane resin: 12.5 parts by weight

Curing agent (Colonate-L, NPU Co., Ltd.): 12.5 parts by weight

Abrasive (alumina): 8 parts by weight

Carbon black: 3 parts by weight

Methyl ethyl ketone: 100 parts by weight

Toluene: 100 parts by weight

Cyclohexane: 100 parts by weight

The components were stirred for 5 hours, mixed and dispersed under the sand for 15 hours, filtered and left for 6 hours to obtain a magnetic coating. The obtained magnetic coating was applied to a polyester film with a thickness of 3 μm, magnetically oriented, dried at 100 ° C., and calendered at a speed of 120 m / sec at a linear pressure of 300 kg / cm, and slurried to prepare 8 mm tape. The tape was allowed to cure for 72 hours at 50 ° C. and 20% relative humidity.

Tapes prepared as described above were measured for the reproduction power, runability and durability in the following manner, the results are shown in Table 1 below.

[One. Playback output]

A 5 MHz signal was recorded on a normal 8 mm video tape recorder, and the reproduction outputs were compared with the reproduction output of the comparison tape (Comparative Example 1) as 0 Hz.

[2. Runability]

The friction coefficient was measured by running the tape which slit the film 1/2 inch width | variety at 20 degreeC and 60% relative humidity using the tape runability tester of Yokohama Systems Research Institute, Japan.

[3. durability]

The polishing tape was wound around a copper cylinder having a diameter of 6.2 mm and a weight of 10 g, and the surface of the magnetic layer was run at 40 mm / sec for 2 hours, and then the degree of contamination of the polishing tape was visually determined. The evaluation criteria were as follows.

(Circle): Pollution cannot be recognized.

(Triangle | delta): A contamination occurs weakly.

X: Pollution remarkably occurs.

Example 2

Except that it was cured for 72 hours at a temperature of 70 ℃, 20% relative humidity was the same as in Example 1, the results are shown in Table 1.

Example 3

Except that it was cured for 72 hours at a temperature 50 ℃, 0% relative humidity was the same as in Example 1, the results are shown in Table 1.

Example 4

Except that it was cured for 72 hours at a temperature of 50 ℃, 40% relative humidity was the same as in Example 1, the results are shown in Table 1.

Comparative Example 1

Except that cured for 72 hours at a temperature of 25 ℃, 20% relative humidity was the same as in Example 1, the results are shown in Table 1.

Comparative Example 2

Except that cured for 72 hours at a temperature of 90 ℃, 20% relative humidity was the same as in Example 1, the results are shown in Table 1.

Comparative Example 3

Except that it was cured for 72 hours at a temperature 110 ℃, 20% relative humidity was the same as in Example 1, the results are shown in Table 1.

[Comparative Example 4]

Except that it was cured for 72 hours at a temperature of 50 ℃, 60% relative humidity was the same as in Example 1, the results are shown in Table 1.

[Comparative Example 5]

Except that it was cured for 72 hours at a temperature of 50 ℃, relative humidity 80% was the same as in Example 1, the results are shown in Table 1.

As shown in the above table, as in Examples 1 to 4, in the case of a tape manufactured under the conditions of curing at a temperature of 50 ° C.-70 ° C. and a relative humidity of 40% or less, the reproducing power, runability and It can be seen that the durability is excellent.

Claims (1)

The magnetic magnetic powder was dispersed in a solvent together with a dispersant, a binder resin, and a curing agent to prepare a magnetic coating. The obtained magnetic coating was wet-coated to a base polyester film for a magnetic recording medium, and then dried and calendered. A method of manufacturing a magnetic recording medium comprising curing a magnetic layer at a temperature of 50-70 ° C. and a relative humidity of 40% or less.