JPS6234346A - Production of optical disk - Google Patents

Abstract

PURPOSE:To prevent the overflow of a photosetting resin from the inside and outside peripheral ends of a transparent substrate and to easily control the thickness of the resin layer by bringing the substrate into tight contact with a stamper for forming grooves while the temp. of the parts thereof corresponding to the inside and outside peripheral parts of the transparent substrate is kept lower than the temp. in the central part. CONSTITUTION:The stamper 6 for forming grooves consists mainly of nickel and pipes 8a, 8b which circulate an antifreeze for cooling are provided to the rear surface of the parts. The stamper 6 is rotated at 25 deg.C room temp. and the photosetting resin 2' is dripped by a dispenser 10 to the central part of the grooves; thereafter, about -10 deg.C antifreeze is circulated to the pipes 8a, 8b. The substrate 1 is then slightly inclined so that the substrate contacts tightly with the stamper 6 gradually from the end. The photosetting resin dropped to the central part of the grooves penetrates gradually to the inside and outside peripheral parts but does not overflow from the inside and outside peripheral ends. UV rays are irradiated on the resin to cure the resin at the point of the time when the resin penetrates to the inside and outside peripheral ends. The substrate 1 is thereafter striped from the stamper 6 and the grooves are thus formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing an optical disc used in a document file device or the like that records and reproduces information using light such as a laser beam.

BACKGROUND OF THE INVENTION In recent years, optical disks have been studied in anticipation of their potential as high-density, large-capacity memories. FIG. 4 shows the structure of a typical optical disc. A light (mainly ultraviolet) curable resin layer 2 formed with grooves on a transparent substrate 1 made of glass, acrylic, etc.
．． First protective layer 3. Magnetic layer 4. and a second protective layer 5.

The method for manufacturing the photocurable resin layer 2 that forms the guide grooves is to rotate the groove forming stamper, drop the photocurable resin 2 onto the center of the groove, and apply the resin to the state shown in Figure 2. Apply. Next, place a transparent substrate 1 such as glass or acrylic on top of this.
Tilt the substrate slightly to avoid air bubbles, and gradually lower it from one direction to make sure it sticks. This method is often used in which the resin is cured by irradiation with light (mainly ultraviolet rays) and then peeled off from the stamper to form guide grooves. Thereafter, a first protective layer, a magnetic layer, and a second protective layer are sequentially formed using a sputtering device or the like.

Problems to be Solved by the Invention However, when bringing the transparent substrate into close contact with the stamper for forming grooves,
The photocuring resin overflows from the inner and outer edges of the substrate.

When this resin overflows, it becomes difficult to control the thickness of the photocured resin layer formed in the grooves, and its removal is also difficult. In particular, removal of the inner circumferential side is difficult because it tends to stain the substrate surface.

Means for Solving the Problems In order to solve the above-mentioned drawbacks, the present invention uses a manufacturing method in which a transparent substrate is brought into close contact with a transparent substrate in a state where the temperature of the outer peripheral portion of the transparent substrate is lower than that of the central portion in a groove forming stamper. .

The viscosity (η
) temperature (T) dependence was determined by Williams et al.
1) It is known that it can be expressed by the following formula.

Here, ΔH is the activation energy of the flow, R is the gas constant,
η1 indicates the viscosity at the reference temperature Tr (K) Increase the viscosity of the photocurable resin in contact with it.

When the photocurable resin dropped into the center of the groove comes into close contact with the transparent substrate, it gradually penetrates into the inner and outer periphery, but because the temperature there is low, the penetration speed of the resin is significantly slowed down, which makes it difficult to manufacture. The above control becomes easier.

Embodiment FIG. 1 shows the groove forming stamper structure of the present invention.
FIG. 1(A) is a sectional view thereof, and FIG. 1B is a bottom view thereof. As shown in Fig. 1, the groove forming stamper is mainly made of nickel, and antifreeze (a mixture of water and ethylene glycol) cooled by a cooler is circulated on the back surface of the outer peripheral part of a transparent substrate 1 such as a glass plate. It has a structure in which pipes sa and sb are provided.

The manufacturing method up to groove formation is shown below. As shown in FIG. 2, the pipes sa and ab of the stamper 6 and the pipes 92L and 9b of the antifreeze solution on the cooler 7 side are temporarily removed.
The stamper 6 is rotated at a room temperature of 26° C., and the photocurable resin 2' is dripped into the center of the groove by the dispenser 10. Next, the pipes 8N, 8b and the pipes 9a, 9b are connected, and after circulating antifreeze at about -10 DEG C., the transparent substrate 1 is gradually brought into close contact with the stamper from the edge, slightly tilted. When the photocurable resin has permeated to the outer peripheral edge of the transparent substrate 1, ultraviolet rays are irradiated to cure the resin, and then the substrate is peeled off from the stamper to form a groove.

FIG. 3 shows the relationship between the viscosity and temperature of the photocurable resin. At 26°C, the viscosity of so cps is -10
In 'C, the pH has increased to about 70,000.

Effects of the Invention As described above, in the present invention, since the viscosity of the photocurable resin is too low unlike in the past, it does not overflow from the inner or outer peripheral edge when it is in close contact with the transparent substrate. This can easily prevent the resin from overflowing from the outer peripheral edge by utilizing the increase in resin viscosity at low temperatures, and has the effect of keeping the thickness of the resin layer constant.

[Brief explanation of drawings]

FIG. 1(M) is a cross-sectional view of the groove forming stamper used in the present invention, FIG. 1(B) is a bottom view thereof, and FIG. 2 is a perspective view showing the state of photocurable resin application in this example. FIG. 3 is a characteristic diagram showing the relationship between temperature and viscosity of the photocurable resin used in this example, and FIG. 4 is a sectional view of the general structure of an optical disc. DESCRIPTION OF SYMBOLS 1...Transparent substrate, 2...Photocurable resin layer, 2'...Photocurable resin, 3...First protective layer, 4... ...Magnetic layer, 6...Second
Protective layer, 6... Stamper for forming grooves, 7...
...Cooler, a&, ab...Pipe, 91L,
9b... Water pipe, 1o... Dispenser. Name of agent: Patent attorney Toshio Nakao and 1 other person/-
- Mototatsu Ichiho 9 1 Figure
6--- Figure 2 7---
Cooler 5! L, De, -Dosuizuzuki/θ--- Tenjin Benpu Figure 3 Meta' JL Watari ('cn

Claims (2)

[Claims] (1) An optical disc manufacturing process in which grooves are formed on a transparent substrate using a photocurable resin, and when the photocurable resin is applied to a groove forming stamper and the grooves are transferred, a temperature distribution is created in the radial direction. A method for manufacturing an optical disc, characterized by using a stamper for forming grooves. (2) The method for manufacturing an optical disk according to claim 1, wherein the groove forming stamper is formed such that the temperature of the inner and outer peripheral portions of the transparent substrate is lower than the center portion.