JPS5953601B2 - Recording disc manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a recording disc in which recording grooves are cut smoothly, noise is reduced, and recording performance is excellent.

A recording system has been conventionally used in which a needle is brought into contact with the surface of a paint layer provided on an aluminum disk base, and while the recording disk is rotated, a groove is cut with the needle to record audio.

The present invention provides a high performance recording disc for use in this recording system.

Conventionally, as a method of applying paint to the disk substrate surface 15, the disk substrate is made flat and the paint is cast onto that surface, or as a method of manufacturing a magnetic disk, the disk substrate is vertically immersed in magnetic paint. A method called dip coating (Japanese Patent Publication No. 14242/1983) is known, in which magnetic paint is applied by rotating. by the way,
In the method of casting the paint onto the surface of the disc substrate, it is difficult to control the amount of paint deposited, and a large amount of excess paint tends to adhere, and furthermore, bubbles are mixed into the paint layer and unevenness appears on the paint layer surface. There are 25 drawbacks. On the other hand, the dip coating method may produce good results as a method for manufacturing magnetic disks by applying a special paint called magnetic paint, but it is difficult to apply this method as is to the magnetic paint, such as the paint for manufacturing recording discs in the present invention. When applied to a paint with a relatively high viscosity of 30 degrees, similar to the above casting method,
It is difficult to control the amount of paint deposited, and it is impossible to eliminate the disadvantages of bubbles being mixed into the paint layer and unevenness appearing on the surface of the coating layer. Generally used recording discs reproduce sound through recording grooves cut into a nitrified cotton paint layer provided on the surface of a 35-piece aluminum disc base. The sound quality of the reproduced sound, that is, the recording performance, depends on the cutting accuracy and the smoothness of the paint layer surface.

In particular, the cutting accuracy of this recording groove is influenced not only by the performance of the coating film depending on the coating composition, but also by the amount of coating coating on the disc substrate and its uniform coating (smoothness).

In order to obtain the optimal paint adhesion amount and uniform coating properties (smoothness) with a paint composition that provides excellent cutting accuracy, it is necessary to use the simple date casting method used in the above-mentioned casting method or magnetic disk manufacturing method. No matter the coating method, it is impossible to avoid fatal defects as a recording disc, such as the inclusion of bubbles in the paint layer, the occurrence of unevenness on the paint surface, and non-uniformity in the thickness of the paint film. The present inventors have completed the present invention as a result of intensive research aimed at solving the above-mentioned problems and providing a recording disc with extremely excellent recording performance.

In the present invention, one or more disk substrates held on a rotating shaft are immersed in a paint tank up to an appropriate position within the lower half (first immersion), the disk substrates are rotated once in this state, and then It is lifted from the paint tank and continues to rotate in the air, smoothing the paint layer due to the fluidity of the paint adhered to the disc base, and substantially drying it. Then, the intrusion position on the disc base during the first immersion is A second immersion is performed with a position displaced by an angle (displacement angle) θ from θ as a new entry position, and after the same treatment as the first immersion, the second immersion is performed in the same direction as the displacement in the second immersion. Third immersion with a position displaced by an angle (displacement angle) θ from the intrusion position on the disk base as a new intrusion position, and the same fourth immersion... nth immersion is required. A uniform coating layer is provided on both sides of the disc substrate by performing the same treatment as the first dipping for each of the third dipping and the n-th dipping until the paint film thickness is obtained. This provides a recording disc with excellent recording performance.

That is, the present invention adopts a multi-coating method in the method of forming a paint layer on the surface of the disc base by immersing the disc base in a paint tank for manufacturing recording discs to an appropriate depth within the lower radius and rotating the tank. It is something. The multiple coating of the present invention is carried out by repeated dipping into a paint tank for manufacturing tone discs, and is characterized in that the dipping is repeated according to a certain rule. For recording discs that record by cutting grooves in a paint layer provided on the surface of the disc's base, the quality of the sound, that is, the recording performance, is determined by the smoothness (uniformity) of the paint layer.

By the way, as already mentioned, simply immersing the disk substrate in a paint tank and rotating it will result in poor adhesion of the paint to the disk substrate, that is, poor smoothness of the paint layer. When recording on a recording disc, there is a lot of noise and the recording performance is extremely poor. The present invention has succeeded in forming a smooth paint layer by dipping the disk substrate into a paint bath and performing spin coating several times according to a certain rule (repeated dipping).

In the present invention, the first rule of repeated immersion is to repeatedly immerse the disk substrate into the paint bath to an appropriate depth within the lower radius.

In other words, instead of completely immersing the entire disc base into the paint tank, the maximum immersion depth is set at the lower half of the disc base, and the fluidity of the paint is utilized by rotating the disc base at an appropriate speed while in this immersed state. A coating layer with excellent smoothness is formed on the entire surface of the disc substrate by a synergistic effect with the second rule of repeated dipping described below. The disc substrate immersed according to the first rule above is kept in its immersed state and rotated for 1 time, then pulled up from the paint tank and continued to rotate in the air to improve the fluidity of the paint attached to the disc base. At the same time, the paint layer is substantially dried. This dipping, one-turn application, lifting, and rotational drying are repeated in sequence, but instead of simply repeating these steps, the dipping is repeated according to a certain rule (the second rule of repeated dipping). This second rule is for displacing the position (position on the disc base) of the second and subsequent entry of the disc base into the paint tank by a constant interval. This displacement means that the position on the disk base that is rotated by a fixed angle θ from the inserted position of the disk base in the first immersion is set as the inserted position of the second immersion, and thereafter in the same rotational direction by a fixed angle θ from the second inserted position. The position on the disk base rotated to is the third entry position,
The position on the disk base rotated by a certain angle θ in the same rotational direction from the third entry position is called the fourth entry position, and the position on the disk base that is rotated in the same rotational direction from the third entry position is called the fifth entry position with the same displacement sequentially. It is something to do. In other words, according to 6 this displacement (second rule of repeated dipping), by sequentially repeating the coating operation consisting of dipping, one-turn coating, lifting, and rotation drying from the first to the n-th coating, the disk substrate surface is By completing multiple coatings on the surface of the paint, a recording disc with excellent recording performance and a coating layer with excellent smoothness can be obtained. The displacement angle θ in the present invention is 36
It may be any angle that evenly divides 0 degrees, and is not particularly limited.

However, 5 Generally, one of 40 degrees, 60 degrees, 90 degrees, and 120 degrees is selected, especially when θ=90, the number of immersions n=
The second rule of 4 repeated immersions is often adopted. Note that, although the disk substrate referred to in the present invention is generally made of aluminum, it is not necessarily limited to this.

Next, the present invention will be explained in more detail with reference to the drawings.

The drawings show the coating process for the disk substrate according to the first rule and the second rule of repeated dipping, and Figures A to 2 illustrate the states of the first to fourth dipping, respectively. be. In the first immersion (Figure A), point a of the aluminum disc base 1 is the entry point, and the immersion depth is the length h within the lower radius of the aluminum disc base 1, and the paint tank is filled with a nitrified cotton paint with a viscosity of 150 CPS. 2 and rotated in the direction of the arrow at a rotational speed of 2 to 5 times/Mi.
When the point a returns to its original position in the paint tank 2 after one rotation, the aluminum disk base 1 is pulled up from the paint tank 2, and then it is dried by rotation in the air, thereby completing the second coating. This completes the process. Next, according to the second rule of repeated immersion that has already been explained, point b, point 6C, and point d, which are respectively displaced by 90 degrees, are set as entry points, and a second immersion (figure opening) is performed.
The third immersion (Figure C) and the fourth immersion (Figure D) are performed in sequence. In the above specific example, the rotation speed of the disc body in the paint tank was set to 2 to 5 times/min, but the rotation speed is not particularly limited, and depends on the composition, viscosity, and paint composition of the paint used. It is necessary to decide based on mutual relationships such as the required thickness of the layer.

The paint layer thickness required for recording discs is 0.2 to 0.3 m.
m is generally considered to be preferable.

By the way, in the case of rotational coating, the amount of paint deposited in one rotation increases in proportion to the rotational speed. Also, depending on the rotation, paint may scatter. That is, the rotational speed in the present invention is set within a range that does not cause paint scattering and at the same time provides the required paint layer thickness. On the other hand, the rotation speed and rotation in air are not limited either, and the rotation is performed until the paint layer on the disk substrate surface is substantially dry.

Also, as the number of immersions increases, the final amount of paint will naturally increase, so as mentioned above, the displacement angle is generally 90°.
It is most preferable that the number of immersions be 4 times, but depending on the viscosity of the paint, the rotation speed, or the final required amount of paint, 60 degrees or 120 degrees may be preferable, and even 40 degrees may be possible. There is also. As explained above, according to the present invention, it is possible to obtain a recording disc with excellent recording performance, which is free from bubbles, has an extremely smooth paint layer, and has an optimal thickness.

[Brief explanation of the drawing]

The drawing is a schematic cross-sectional view showing one embodiment of dip coating in the method for manufacturing a recording disc of the present invention, and A to B indicate first to fourth dipping, respectively. DESCRIPTION OF SYMBOLS 1... Disc base, 2... Paint tank, 3... Lower radius of disc base, 4... Paint, a... First immersion position, b...
...Second immersion position, c...Third immersion position, d...Fourth immersion position, h...Immersion depth.

Claims (1)

[Claims] 1. One or more disc substrates held on a rotating shaft are immersed in a paint tank up to an appropriate position in the lower half thereof (the first
In this state, the disk substrate is rotated once, then pulled up from the paint tank and continued to rotate in the air to substantially dry the paint layer, and then the angle (displacement The second immersion is performed with a displacement of angle) θ, and the first
After a drying process similar to the immersion, a third immersion was performed in which the disk substrate was displaced by an angle (displacement angle) θ in the same direction as the displacement in the second immersion, and a third immersion was performed in the same manner. 4th immersion...Nth immersion is performed sequentially, 3rd immersion...
...A method for manufacturing a recording disc, characterized in that a uniform coating layer is provided on both sides of a disc substrate by performing a drying process similar to the first immersion in each of the n-th immersions. 2. The method for manufacturing a recording disc according to claim 1, wherein the displacement angle θ is any one of 40 degrees, 60 degrees, 90 degrees, and 120 degrees. 3. The method for manufacturing a recording disc according to claim 1, wherein the displacement angle θ is 90 degrees. 4. The method for manufacturing a recording disc according to claim 3, wherein the number of immersions is n=4.