JPS60131651A - Signal recording stamper - Google Patents

Abstract

PURPOSE:To eliminate strains, dislocations, haze, stains, etc. which are produced in a molding mode by decreasing the thickness of a stamper toward its outer circumference from the inner circumference. CONSTITUTION:The thickness of a stamper 8 is reduced toward its outer circumference 10 from the inner circumference 9, and the thickness of the circumference 10 is reduced by a proper amount as compared with that of the circumference 9. Owing to the tapered thickness of the stamper 8, the gap formed between a metallic mold cavity and the stamper 8 is increased toward the circumference 10. This stamper facilitates an easy flow of resin and also obtains the coincidence of the resin flowing speed between the metallic molding cavity side and the stamper side.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a signal recording stamper in which information signals such as video discs, digital audio discs, video files, and document files are recorded in the form of uneven surfaces;
This invention relates to a signal recording stamper having track grooves. Injection molding is a method for transferring signals from a signal recording stamper.

There are methods using injection compression molding and ultraviolet curing resin, but
The present invention particularly relates to injection molding and injection compression molding.

Structure of conventional example and its problems Normally, a recording signal stamper used for injection molding or injection compression molding has the same thickness on the inner and outer circumferences.The conventional signal recording stamper will be explained below with reference to the drawings. do. FIG. 1 is a sectional view of a conventional stamper. Most have a thickness of 0.2 to 0.4 mm and 1 J, and there is almost no difference in thickness between the inner and outer circumferences. Using this stamper, a signal is transferred by injection molding or injection compression molding to produce a disk as follows.

As shown in FIG. 2, the stamper 1 is fixed to the mold core 2 with the holder 3 with the recording signal side facing up, pressed down with the outer periphery presser 4, and closed with the cavity 5.

However, at this time, in order to release resin gas generated during molding, a clearance must be provided between the stamper 1 and the stamper outer periphery holder 4 at the outer periphery of the cavity, and the cavity side injection port. 6
Inject well-dissolved resin. The injected resin presses the stamper 1 against the mold core 2 by the pressure at the time of injection, and flows from the inner circumference to the outer circumference. The gas generated at this time escapes through the gap between the stamper 1 and the stamper holder 4 and the mold cavity 5. When the resin is injected to the outer periphery, the resin is cooled as it is or with pressure applied by moving the mold core 2 to harden the resin and transfer the signal. Next, the mold core 2 is removed from the cavity, and the center spool is punched out using a punching pin 7 to make a center hole, and the disk on which the signal has been transferred is removed from the stamper. Next, a reflective film is applied to the signal side of the formed disc by sputtering or vapor deposition, and a protective film is applied on top of this to finish the disc.

However, the above method has the following problems.

First, the resin gas generated during molding escapes through the gap on the outer periphery of the mold, but if the thickness of the stamper 1 is the same on the inner and outer peripheries, the gap between the mold cavity 5 and the stamper 1 is on the inner and outer peripheries. Since both of the molded parts become constant, the flow of the resin becomes worse as it goes to the outer periphery, and the resin entrains gas, making it easy for mist and stains to occur on the signal side of the molded product. Secondly, since the surface of the stamper 1 has unevenness that varies from hundreds to thousands of recording signals, the stamper surface has greater friction than the mold cavity 5 side, and the thickness of the stamper 1 increases. If is constant on the inner and outer circumferences, there will be a difference in the flow speed of the resin between the mold cavity 5 side and the stamper 1 side, which will easily cause distortion and faults in the molded product, making it difficult to set the molding conditions. Become. Third,
Normally, the back side of Stanno<-1 is polished to a mirror finish, but it is very difficult to finish the stamper with a constant thickness on both the inner and outer circumferences during polishing, and the control of this process is both important and difficult. come.

OBJECTS OF THE INVENTION An object of the present invention is to provide a stamper that eliminates the above-mentioned problems by changing the thickness of the stamper between the inner and outer peripheries to improve resin flow and gas release.

Structure of the Invention The signal recording stamper of the present invention has a thinner thickness from the inner circumference to the outer circumference, so that the flow speed of the resin on the stamper side and the mold cavity side is the same, and the gas It improves punching and eliminates distortions, faults, haze, stains, etc. that occur during molding.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a sectional view of the stamper 8 in one embodiment of the present invention. The thickness of the stamper 8 is sloped from the inner circumference 9 to the outer circumference 1○, and the thickness of the outer circumference 10 is made 10 microns thinner than the thickness of the inner circumference 9. There are several methods for producing such a stamper 8. Firstly, in the plating process during stamper production, the thickness can be changed on the inner and outer peripheries by changing the plating speed on the inner and outer peripheries;
Second, when polishing the back side of the stamper, polish the stamper 12 with paraffin or the like with the signal side facing down on the plate 11 that matches the inclination of the stamper to be manufactured as shown in Fig. 4. When molding is performed using a stamper with a thickness sloped in this way, the gap between the mold cavity and the stamper is tilted toward the outer periphery. Because it is wider, resin flows better and
The flow speed of the resin on the mold cavity side and the stun nozzle side becomes the same. When transferring a signal from a stamper C- that has an uneven signal or a track groove, the thickness of the stamper is sloped from the inner circumference to the outer circumference, and the outer circumference is thinner than the inner circumference to facilitate degassing. In addition to improving the flow of the resin, it also makes the flow speed of the resin on the mold cavity side and the stamper side the same, thereby eliminating resin faults and distortions that occur during molding. It also eliminates mist and stains that occur when resin entrains gas. Furthermore, it is possible to eliminate damage to the stamper due to burns caused by gas and adhesion of resin to the stamper signal surface.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional signal recording stamper, Fig. 2 is a sectional view of the conventional signal recording stamper attached to a mold for injection molding or injection orthogonal injection molding, and Fig. 3 is a sectional view of the present invention. A cross-sectional view of a signal recording stamper in an embodiment of
FIG. 4 shows a signal recording stamper according to an embodiment of the present invention.
FIG. 3 is a sectional view of the stamper attached to the plate during processing. 1... Conventional stamper 12... Gold W
Core, 3...Holder, 4...Stamper holder, 6...Mold cavity, 6...
...Resin injection port, 7...Punching bottle, 8.
...Stamper 19 of one embodiment of the present invention...
Stamper inner circumference, 1o...Stamper outer circumference, 1
1... Polishing plate, 12... Stamper 0 before polishing

Claims (1)

[Claims] A signal recording stamper 6 characterized in that the thickness of the stamper having uneven signals or track grooves formed on its surface is thicker on the inner circumferential side and thinner on the outer circumferential side.