JPH01300441A - Production of substrate for optical recording medium - Google Patents

Abstract

PURPOSE:To suppress the generation of burrs by irradiating the inner edge and outer edge of a base material with condensed light along the respective edges and feeding an inert gas under pressure locally to the point irradiated with said light or executing said feeding within the chamber of an inert gaseous atmosphere. CONSTITUTION:The inner edge and outer edge of the base material 2 having a central hole are irradiated with the condensed light along the respective edges at the time of producing the substrate for the recording medium by successively laminating a photosetting resin 3 and the base material 2 on a forming mold 4 and solidifying and sticking the resin 3. The insert gas is simultaneously fed under pressure to the point irradiated with the light to cure the resin 3 spread to the position irradiated with the light. The above-mentioned stage is otherwise executed in the chamber of the inert gaseous atmosphere and thereafter, the entire part of the resin 3 is irradiated with light and is thereby cured. The disturbance of the curing of the resin by oxygen is decreased by the effect of the inert gaseous atmosphere in this way and the generation of the burrs which are the major source of generating dust is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a substrate with guide grooves used for an optical recording medium capable of recording and reproducing information using a light beam. For more details, please refer to 2P (Photo poly
This invention relates to an improvement in a substrate manufacturing method called the mer (photocurable resin) method.

[Conventional technology]

In order to perform high-density recording, it is necessary to form optical guide grooves on the surface of the substrate of an optical recording medium.

Several methods have been conventionally known as methods for forming the same. One method is to apply a hardening resin to a mold (called a stamper) that has unevenness corresponding to the shape of the guide groove, place the base material on top of this, and then irradiate it with light. There is a method in which the guide groove is fixed to the base material by hardening the resin. This method has excellent transferability of the guide groove shape, and has the advantage that optical distortion of the substrate can be reduced compared to other guide groove forming methods.

[Problem that the invention is trying to solve]

However, the following problems remained unsolved. Figure 2 shows
It is a figure which shows the state after resin hardening when forming a guide groove by the said conventional method. In this method, since the resin 3 has fluidity before curing, it may protrude from the outermost edge of the substrate 2, and this protruding portion is cured by light irradiation, etc., and is exposed to the outside of the substrate 2. It was not uncommon for the blade to have a pointed end as shown in the figure. In addition, since there is a minute gap in the fitting part between the central shaft 1 located at the center of the stamper 4 and the base material 2, the resin will also protrude from this part and harden, resulting in small cracks. This makes it difficult to release the stamper 4 from the base material 2 to which the guide grooves are fixed.

When the stamper 4 is released from the substrate with guide grooves in which firmness has occurred, the edges having the pointed ends are likely to be chipped. The chipped particles were often deposited as dust (=f) on the surface of the substrate where static electricity was generated due to peeling charge.

Further, when removing paris, the removed paris sometimes becomes dust and adheres to the surface of the substrate. This dust was one of the causes of defects in recording media and recording errors. Furthermore, when a recording layer is laminated on the guide groove to which the dust has adhered, the dust cannot be completely covered by the laminated film due to the step difference, resulting in pinholes, which causes the following problems. That is, the problem is that moisture and oxygen enter through the pinholes and corrode the recording layer, thereby degrading its recording characteristics. As a method to solve the above problem, Japanese Patent Application Laid-Open No. 61-222727
No. ``Method for manufacturing a substrate for an optical recording medium'' discloses a method for preventing resin from extruding from the inner and outer peripheral edges of a substrate using a mask. Another possible method is to irradiate the condensed light along the inner and outer peripheral edges of the substrate to prevent the resin from protruding. Such a method is quite effective in solving the above problems. However, with this method, there are problems with alignment between the base material and the mask or the focused light, and the accuracy of the stopping position of the resin deteriorates due to light diffraction. In this case, the curing level differs in the thickness direction of the resin, and the resin close to the focused light is cured, but the resin far away remains uncured. For this reason, there is a problem that the uncured resin flows and the accuracy of the stop position is deteriorated, and if the resin has low viscosity, the resin spreads quickly over the entire surface of the board, and even the inner and outer peripheral edges are irradiated with the collected light. There is a problem that the resin will flow out before the next irradiation and the accuracy of the resin stop position will deteriorate. Furthermore, if the resin has strong anaerobic characteristics, the light that hardens the resin will be placed at the desired resin stop position. Even if it is irradiated, the curing is inhibited by oxygen in the air and it sticks out.
Difficult issues remained.

The present invention has been made in view of the above-mentioned problems, and its purpose is to prevent dust from adhering to the surface of the substrate by suppressing the occurrence of flash when manufacturing substrates with guide grooves using a stamper. An object of the present invention is to provide a method for manufacturing a substrate for an optical recording medium that can prevent the above problems.

[Means to solve the problem]

The above purpose is to sequentially stack a photocurable resin and a base material with a central hole on a mold with unevenness corresponding to the shape of guide grooves and information, solidify the resin, and harden the base material. In a method of manufacturing a substrate for an optical recording medium with guide grooves or information by adhering, this can be achieved by sequentially carrying out the following steps (1) and (2) or (2) and (2).

■ Irradiate the inner and outer edges of the base material with condensed light (light from a condensing lens, light from an optical fiber, etc.) along each edge, and place an inert A step of hardening the resin that has been spread to the position irradiated with light by pumping gas.

By pumping this inert scum, the surface of the resin where the light is irradiated becomes an inert gas atmosphere, which reduces the inhibition of hardening of the resin due to oxygen.

Furthermore, at the outer peripheral end, the force of pushing the resin back toward the inner peripheral side due to the pressure of the inert gas and the force of spreading it in the circumferential direction prevent the resin from protruding, making it easier to control the stop position.

(2) A step of curing the entire resin by irradiating the entire resin with light.

(2) A step of carrying out the step (1) above in a chamber with an inert gas atmosphere.

This eliminates the effect of oxygen on curing inhibition, making it easier to align the focused light and control the stopping position.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example 1 An optical recording medium substrate was manufactured as follows (first
(See Figures (a) and (b)).

First, the ultraviolet curing resin 3 was applied onto the stamper 4 in a donut shape. A glass substrate 2 having an outer diameter of 130 mm, a thickness of 1.2 mm, and an inner diameter of 15 mm was stacked on this resin 3. Then, an ultraviolet spot irradiation device (product name: Toscure 20
An optical fiber 5 connected to an ultraviolet lamp 6 made by 0PN (manufactured by Toshiba Denzai) was arranged. At this time, the distance between the end face of the optical fiber 5 and the surface of the base material 2 was set to 1 ml11, so that the optical fiber 5 was perpendicular to the base material 2. Note that each optical fiber 5 was placed directly above a position where the resin 3 was not desired to spread further. And about 30 stampers on the outer periphery.
A nitrogen nozzle 7 was arranged so as to be tilted at an angle so that nitrogen was discharged at the light irradiation position of the fiber. Further, a nitrogen nozzle 8 was disposed on the inner circumference along the axis l so that nitrogen was discharged at a position where the light from the optical fiber was irradiated in the same way as on the outer circumference. Further, the pressure of this nitrogen was 3 kg/cm'.

Next, the inner and outer edges of the base material are irradiated with ultraviolet rays under conditions such that the intensity of ultraviolet rays is 500 mW/am' at a distance of 1 cm from the end face of the optical fiber 5, and nitrogen is injected from the nitrogen nozzle 7.8. I spat it out. Thereafter, when the stamper was rotated, ultraviolet rays were irradiated circumferentially only on a part of the inner edge and outer edge of the base material 2, while the resin 3 was pushed and spread.

When the resin 3 reaches the position where the light is irradiated, its spread is suppressed by the pressure of nitrogen, and it is cured by ultraviolet rays, forming the base material 2.
It is now in a state where it does not protrude from the edge. Thereafter, the entire base material 2 was irradiated with ultraviolet rays with a light intensity of 230 mW/crn' for 30 seconds to harden the resin 3. Subsequently, the layer of resin 3 having guide grooves and the base material 2 which have been cured and fixed are peeled off from the stamper 4,
It was used as a substrate for optical recording media.

Example 2 An optical recording medium was prepared in the same manner as in Example 1, except that two optical fibers and two nitrogen nozzles were used for the inner edge and two for the outer edge, and each was arranged on a straight line passing through the center of the circle. The substrate was manufactured. Note that both of the inner circumferential wires were placed directly above the position where the resin was not desired to spread any further. Two optical fibers on the outer periphery and nitrogen nozzles were arranged in the same way.

By using two optical fibers and two nitrogen nozzles for the inner and outer edges, the time interval at which the resin at the inner and outer edges is irradiated with light becomes shorter. If this time interval becomes longer, the resin will spread beyond the desired stop position by the time the light is irradiated next time, and the accuracy of the stop position will deteriorate.

Example 3.4 The condensed light was irradiated not perpendicularly to the substrate, but at an angle of approximately 10 degrees to the outer circumferential side outward and inward to the inner circumferential side, and
An optical recording medium substrate was manufactured in the same manner as in Example 1.2, except that the outer nitrogen nozzle was arranged at an angle of about 60 degrees with respect to the stamper. By tilting the outer circumferential side of the condensed light outward, the light flows outward, thereby suppressing the diffracted light toward the inner circumference where the resin spreads. Furthermore, by tilting the nitrogen nozzle, the distribution of nitrogen pressure applied to the resin changes. Especially when the viscosity of the resin is low, when the force pushing it toward the inner circumference of the board becomes strong, the resin curls up and protrudes due to that force. Sometimes it happens. Therefore, by changing the pressure distribution, it is possible to suppress the protrusion caused by the curling up.

Examples 5 to 8 As an example according to claim 2, a stamper is placed in the chamber.
A substrate for an optical recording medium was manufactured in the same manner as in Examples 1 to 4 except that a substrate, an optical fiber, and a nitrogen nozzle were placed in the chamber to create a nitrogen atmosphere. By the method of the above-mentioned embodiment, even if the ultraviolet curable resin has a strong curing property, there is little inhibition of curing by oxygen, and the resin can be stopped at a desired location.

The present invention is in no way limited to the above embodiments. For example, a base material such as polycarbonate, acrylic, or epoxy resin can be used instead of a glass base material.

Note that when a highly curable resin is used as the curable resin, it will be cured by a slight diffraction of light, so the accuracy of the resin stopping position tends to deteriorate. In such a case, the accuracy of the stopping position can be improved by reducing the distance between the end face of the optical fiber or condensing lens and the substrate surface, or by reducing the condensing diameter to suppress light diffraction. In addition, by changing the nitrogen pressure, the force applied to the resin changes, allowing control of the spreading speed and improving stopping position accuracy.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to harden the resin at a desired position before the resin reaches the innermost and outermost edges of the substrate, and the resin protrudes from the inner and outer periphery of the substrate. This eliminates the formation of dust, which is the main source of garbage. Therefore, the adhesion of dust to the substrate with guide grooves can be significantly reduced, and a highly reliable substrate for an optical recording medium can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of the method of the present invention. FIG. 2 is a sectional view after the resin is cured by the conventional method. 1: Central axis 2: Substrate 3: Curable resin 4 Nistampa 5: Optical fiber 6: UV lamp 7.8: Nitrogen discharge nozzle Figure 1 Figure 2

Claims (1)

[Claims] 1) A photocurable resin and a base material having a center hole are sequentially laminated on a mold having unevenness corresponding to the shape of guide grooves and information, and the resin is cured and the base material is cured. A manufacturing method for manufacturing a substrate for an optical recording medium with guide grooves or information by adhering it to a material, characterized in that the following steps (1) and (2) are performed in order. (1) The inner and outer edges of the base material are irradiated with focused light along each edge, and an inert gas is locally pumped into the area where the light is irradiated. (2) Curing the resin that has been spread to the irradiated position (2) Curing the entire resin by irradiating the entire resin with light 2) The step (1) is carried out in a chamber with an inert gas atmosphere. 2. The manufacturing method according to claim 1, wherein the manufacturing method is carried out within a chamber.