JPH0367749B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for forming a surface film on the surface of a disk-shaped body, and relates to a method for forming a protective film to protect the surface of a disk-shaped recording medium (disc). It can be used for processes etc.

Structure of conventional examples and their problems Conventionally, a recording medium layer is provided on one side of a disc-shaped transparent substrate, or a predetermined information signal is recorded as uneven bits. A device has been developed in which two disks are pasted together to face each other, and a light beam is irradiated from the surface of the disk to record and reproduce information.

The transparent substrate in these disks is
Since resin materials such as cast acrylic and polycarbonate are used from the viewpoint of economy and safety, there is a problem that the exposed outer surface is easily scratched during use. For this reason, it has been considered to protect this exposed surface by forming a coating with higher hardness.

As shown in FIG. 1, the conventional method for forming this protective film is to place a disk 4 whose center hole 5 is fixed to a rotating shaft 3 in a dip tank 2 containing a coating liquid 1 in the vicinity of the center hole 5. Rotate at low speed while immersed until the center hole 5 is opened as shown in Figure 2.
A protective coating 6 was formed in a predetermined area near the area.

However, when using this method to sequentially form coatings on a large number of disks, foreign matter adhering to the surface of the disk gets mixed into the coating liquid 1, and this foreign matter re-adheres to the disk surface, resulting in poor recording and playback characteristics. There is a problem that damages the

For this purpose, the coating liquid in the dip tank 2 is circulated and filtered through a filter, but it is difficult to keep the coating liquid in the dip tank 2 clean at all times when tapes are inserted one after another. be.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned problems and is configured so that only a clean coating liquid is always applied to the disk surface.

Structure of the Invention The present invention eliminates foreign matter by pouring the filtered coating liquid below the center hole of a disk that is driven to rotate around the center hole in a plane substantially perpendicular to the ground. The purpose is to form a small protective film on the disk surface.

DESCRIPTION OF EMBODIMENTS FIGS. 3 and 4 are a front view and a side view of a main device in an embodiment of the film forming method of the present invention.

In FIGS. 3 and 4, the center hole 5 of the disk 4 is fixed to the rotating shaft 3, as in the conventional example, and the disk 4 is rotated in the direction of the arrow in a plane perpendicular to the ground.

7 and 8 are coating liquid injection nozzles;
Below the center hole 5 of the disk 4, the coating liquid 1 is poured onto the disk 4 from both sides.

Reference numeral 9 denotes a recovery tank for the coating liquid 1 provided below the disk 4, and is configured so that the coating liquid 1 in the recovery tank 9 and the disk 4 do not come into contact with each other.

The coating liquid in this recovery tank 9 is pumped 1
0 and is guided to the nozzles 7 and 8 via a circulation path including a filter 11.

In the above configuration, the coating liquid poured onto the disk 4 passes through the disk 4 and falls into the collection tank 9, and is applied to the outer circumference of the disk as the disk 4 rotates.

At this time, the rotational speed of the disk is preferably set to such a speed that the coating liquid immediately after application does not fall onto the rotating shaft 3 when it comes directly above the rotating shaft 3 after half a rotation of the disk.

For example, when applying a coating liquid with a viscosity of 4 cp to a disk with a diameter of 20 cm, the rotation speed is preferably about 30 to 50 rpm, and the number of rotations of the disk during this application is preferably about 3 to 4 times. The coating liquid collected in the recovery tank 9 is cleaned by a filter 11, and the disk 4 is always coated with clean coating liquid.

Since the coating liquid layer applied by the above process is not necessarily uniform, it is rotated for about 30 seconds or more at a rotational speed within twice the rotational speed at the time of coating, and the coating liquid layer is made almost uniform by the surface tension of the coating liquid. Rotate at a high speed of about 1800 rpm for about 2 minutes to make it uniform.

In the embodiment, one nozzle is provided on one surface of the disk, but a plurality of nozzles may be provided.

Effects of the Invention As described above, according to the present invention, since the coating liquid is always poured onto the disk in a clean state, it is possible to form a film with less adhesion of foreign matter. Therefore, it also has the effect of washing away foreign matter adhering to the disk.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view showing the main parts of a conventional coating forming apparatus, FIG. 2 is a plan view of a disk on which a protective coating is formed, and FIG. 3 is an apparatus used in the coating forming method of the present invention. FIG. 4 is a partially cutaway front view showing one embodiment of the present invention, and FIG. 4 is a sectional view of the same side. 1... Coating liquid, 3... Rotating shaft, 4...
Disk, 7, 8... Nozzle, 9... Collection tank, 1
0...pump, 11...filter.

Claims (1)

[Claims] 1. While rotating the disc-shaped body on which the coating is to be formed at a first rotational speed in a plane perpendicular to the ground, pour the coating liquid below the center of rotation of the disc-shaped body to apply the coating liquid. After coating the surface of the disc-shaped body, the disc-shaped body is dried by a step of rotating at a second rotational speed within twice the first rotational speed, and then a step of rotating at a high speed. Method for forming a film on a disk-shaped body.