JPS5939813B2 - Surface treatment method for magnetic tape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface treatment method for improving the slipperiness of the surface of a magnetic tape.

Generally, the surface of a metal thin film type magnetic tape has poor lubricity, which poses a problem in practical use. Conventionally, various methods have been devised to improve the surface slipperiness of this type of magnetic tape. In particular, a method of applying an ultraviolet curing epoxy resin layer to the surface and curing it has been common. The present invention relates to a surface treatment method for applying and drying an ultraviolet curing resin etc. to effectively obtain smoothness on the surface of a magnetic tape. An embodiment of the apparatus used to carry out the method of the present invention will be described below with reference to the drawing of FIG.

In the figure, reference numeral 1 denotes an original fabric of a metal thin film type magnetorip whose magnetic layer is made of a magnetic metal thin film, and is wound with the magnetic surface facing inside. 2 is a running magnetic tape, which is indicated by a dashed line.

3 is a roller that keeps the magnetic tape running, and is installed so as to reduce rotational friction, and the surface of the roller is polished to a roughness of about 0.1 to 1.0 μm to remove wrinkles.

4 is a roller that determines the running speed of one magnetic element, and one is a rubber roller, which is used in a state where the magnetic tape is nipped.

5, 5', and 5'' are rollers of a coating machine, and the coating machine in this example is a three-roll gravure roll coater type.

Further, 5 is a gravure roller, and 6 is a coating liquid.
This coating liquid 6 is composed of an ultraviolet curing resin, a curing agent, a sensitizer, a lubricant, an antistatic agent, and a diluting solvent, and has a viscosity of 2.
It is about 00 cps to 5 cps. 5' is a transfer roller from the gravure roller 5, which is a rubber roller.

5'' is a metal roller that is a backup roller that supports the magnetic tape.

These three rollers 5, 5', 5'' are pressurized with an appropriate load, and their speeds are also set at an appropriate speed difference within a narrow range. He is a doctor who does everything.

Then, in the coating machine, a low-viscosity coating liquid is thinly and uniformly applied to the magnetic surface of the magnetic tape. 8 is a drying oven;
The structure is such that hot air is blown onto both sides of the magnetic tape to dry it, and the magnetic tape is supported by the air pressure.

Additionally, an ultraviolet lamp is installed on the exit side to cure the ultraviolet curing resin. In the drying oven 8, 9 is a hot air outlet, 10 is a suction port, and these ports 9, 1
0 are respectively provided on the upper surface side and the lower surface side of the magnetic tape. 11 is a common duct for supplying hot air, and 12 is a common duct for exhaust, which are also located above and below.

13 is an ultraviolet lamp, and 14 is its reflecting mirror.

In the drying oven having such a structure, when the coating liquid 6 is applied to the magnetic surface of the magnetic tape by a coating machine and passes through the coating machine, the solvent first evaporates. At this time, the fact that the magnetic tape is floating has a great effect on the uniformity of the film thickness, and the uniformity of the film thickness is very good. Further, during the process of evaporation of the solvent, the lubricant is exposed on the surface and a film is formed. The film formed in the drying oven is cured with an ultraviolet lamp 13 to form a slippery thin film layer. 1
5 is a wound magnetic tape.

FIG. 2 shows a test device for evaluating the surface smoothness of a magnetic tape surface-treated with such a device.

In the figure, 16 is a magnetic tape to be tested, 17 is a weight, 18 is a Nutren gauge for measuring frictional force, 19 is a cylindrical standard test piece for measuring frictional force, and 20 is a test piece 1.
9 is a rotating motor, which rotates the test piece 19 at a constant speed and measures the frictional force with the magnetic tape. The friction coefficient is measured as follows.

The load on the test piece 19 when it is not moving is T. The friction coefficient μ is expressed as μm10−1−π.

FIG. 3 shows an example of the friction coefficient of the magnetic tape when the viscosity of the coating liquid is changed.

The coating liquid is composed of resin, lubricant, solvent, etc.
The viscosity was adjusted by adjusting the ratio of resin and solvent. The characteristics shown in Figure 3 were obtained, and at 200 cps, the friction coefficient decreased to 0.5 or more. When this friction coefficient reaches around 0.5,
In actual use, the running performance deteriorates and the fluctuation in output becomes large.
On the other hand, on the low viscosity side (less than 5 cps), the amount of resin is reduced and only the solvent remains, resulting in increased friction. FIG. 4 shows an example of j measurement when 10% resin was added to the solvent, and it can be seen that a low coefficient of friction is exhibited when the initial coating amount is in the range of 0.2 to 4.0 μ. FIG. 5 shows the difference in friction coefficient depending on the conditions during hot air drying.

It can be seen that there is a large difference in lubricity between double-sided drying and single-sided drying. As is clear from the above examples, when a magnetic tape is surface-treated by the surface treatment method of the present invention, the initial slipperiness of the magnetic surface with a coefficient of friction of about 0.6 to 0.7 becomes 0.5 or less, the slipperiness of the magnetic surface improves,
This improves the contact with the magnetic head during magnetic recording and reproduction, reduces fluctuations in output, and enables the reproduction of high-quality audio and other output signals, which has great industrial potential. It is something.

In the embodiments of the present invention, the coating liquid is applied using a gravure roll coater method, but the application is not limited to this, and other force methods may be used, and the coating liquid may be dried using ultraviolet rays. The method is not limited to drying, and depending on the type of resin, means such as electron beams or heating may be used.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional front view of an embodiment of a device used to carry out the force method of the present invention, Fig. 2 is a perspective view of a testing device for evaluating the surface smoothness of magnetic tape, and Fig. 3 4 is a characteristic diagram of the friction coefficient with respect to the viscosity of the coating liquid, FIG. 4 is a characteristic diagram of the same with respect to the initial coating thickness, and FIG. 5 is a characteristic diagram comparing the same characteristics between double-sided drying and single-sided drying. 2... Magnetic tape, 5, 5', 5'5...
...Coating machine roller, 6...Coating liquid, 8...
... Drying oven, 13... Ultraviolet lamp.

Claims (1)

[Claims] 1. A coating liquid with a base viscosity of 200 to 5 cps containing a solid resin, a curing agent, a lubricant, and an antistatic agent is applied onto the surface of the magnetic metal thin film of a magnetic tape in which the magnetic layer is made of a magnetic metal thin film.
．． After coating to a thickness of 2 to 4.0 μm, hot air below the softening temperature of the magnetic tape is blown from both sides of the magnetic tape, and the magnetic tape is passed through a drying oven while floating to dry the solvent and control the shape of the surface resin layer. A method for surface treatment of a magnetic tape, which comprises completely curing a lubricating resin layer formed on the surface of the magnetic tape.