JPH08147774A - Method for manufacturing substrate for optical recording medium - Google Patents

Abstract

PURPOSE: To produce a substrate for an optical recording medium having satisfactory transfer performance and thickness precision and almost free from optical strain without causing any distortion and deformation of an edge part of a thermoplastic resin sheet. CONSTITUTION: A thermoplastic resin sheet is heated, a pattern is transferred and formed by pressing with a roll-shaped stamper and the objective substrate is produced. At the time of heating the sheet, an edge part of the sheet is not heated and the sheet is pressed and conveyed while holding the edge part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical recording medium substrate, and more particularly to a method for manufacturing an optical recording medium substrate in which a molding pattern of the optical recording medium substrate is continuously formed.

[0002]

2. Description of the Related Art At present, optical recording media are widely used as optical disks, optical tapes, optical cards and the like, and various manufacturing methods are known.

For example, compression molding (compressi) in which a softened plastic material is pressed by a mold and solidified.
on Mold) method, injection molding (Injection Mold) method in which a molten plastic material is injected and solidified in a mold provided with a stamper, and 2P (Photo Poly) for transferring a pattern using an ultraviolet curable resin.
Examples include a merging method, a casting method in which a plastic material is poured into a pattern-provided mold to be solidified and then demolded.

Further, among the molding methods, particularly the molding of fine shapes has made remarkable progress, and many proposals have been made especially for the groove molding of tracking grooves, information pits and the like on the surface of a substrate for an information recording medium. It was In recent years, a method of continuously performing fine molding has been proposed in order to reduce the cost and improve the mass productivity.

As a typical method thereof, Japanese Patent Laid-Open No. 56-
As disclosed in Japanese Patent No. 86721, a thermoplastic resin sheet is heated and a melted resin sheet is provided with a stamper before the resin sheet is cured; and a pressure roll arranged so as to face the stamper roll. This is a method of transferring the pattern to the resin sheet by pinching it. FIG. 3 is an explanatory view showing a conventional method for manufacturing a substrate for an optical recording medium showing such a method.

However, in the above method, the entire resin sheet is heated, and the weight of the sheet causes uneven thickness at both ends of the sheet, which may deform the resin sheet before molding. Also, the conveyance of the resin sheet molded between the rolls,
As shown in FIG. 3, it was performed by taking a sheet. According to this method, the resin sheet is subjected to the tension of take-up immediately after it is released from the molding roll and before it is completely cooled.

[0007] The tension applied to the resin sheet is non-uniform due to the take-up condition of the sheet, sheet skew / thickness unevenness and the like. Since the resin sheet has not been completely cooled immediately after being molded, there is a drawback that a new optical strain is generated in the resin sheet during transportation due to the tension of pulling.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional techniques in order to improve the drawbacks of the conventional example, and the end portions of the thermoplastic resin sheet are not twisted or deformed. It is an object of the present invention to provide a method for producing a substrate for an optical recording medium, which has good transferability and has little optical distortion.

[0009]

That is, according to the present invention, a thermoplastic resin sheet is heated and a stamper roll provided with a stamper having a preformat pattern formed on the roll surface of the thermoplastic resin sheet and a pressure roll are provided. Using a method for producing an optical recording medium substrate for transferring and forming a pattern by embossing, in heating the thermoplastic resin sheet,
Transfer the pattern without heating the end of the resin sheet,
A method for manufacturing an optical recording medium substrate, characterized in that the resin sheet is conveyed while holding the edge portion of the resin sheet.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view showing an example of an apparatus used in the method for manufacturing a substrate for an optical recording medium of the present invention. FIG. 2 is a schematic view showing an example of a light-shielding plate, a molding roll, and a conveying jig used in the method for manufacturing an optical recording medium substrate of the present invention.

In the present invention, in FIGS. 1 and 2, the thermoplastic resin sheet 1 is continuously moved from the roller 9 to introduce the resin sheet into the heating chamber 2. In the heating chamber 2, the light-shielding plate 4 is arranged at a position corresponding to the sheet end so that the end of the thermoplastic resin sheet, which should be the sheet conveying portion, does not receive heat, and only the central portion of the sheet is provided with the infrared lamp. Heat by irradiation. As a method of heating the sheet, the infrared lamp 3 may be used.

The light-shielding plate 4 may be of any type as long as it can block the light hitting the resin sheet so that the resin sheet does not receive the light irradiated by the lamp. For example, copper, nickel, A
Metals such as l, brass, alloys such as stainless light alloys, BN,
SiN, glass, ceramics such as Al ₂ O ₃ and titanium nitride, asbestos, rock wool, diatomaceous earth, basic magnesium carbonate, calcium silicate, etc., also multi-cellular foam glass, fire-resistant insulating bricks, Al, plastic, etc. Examples include corrugated heat insulating materials having

The heated resin sheet passes between a stamper roll 5 provided with a stamper having a preformat pattern formed on the roll surface at the exit of the heating chamber 2 and a pressure roll 6, and the pattern of the stamper 13 is transferred. To be done.

The stamper roll 5 is prepared by providing the stamper 13 for forming a pattern by a method of winding a long sheet-like stamper having a circumferential length around the roll or a method of cutting a forming pattern on the circumferential roll main body. Good.

Further, the roll may be a cylindrical flat roll, but for example, a stepped roll provided with an uneven portion on the roll may be used in consideration of the shape of the stamper and the formation state of the sheet end portion, or the sheet. You may use the thing of a short roll surface length so that a roll may not hit an edge part.

The resin sheet having a desired pattern formed in the central portion of the sheet is conveyed with its sheet end held by the conveying jig 7. Conveyance tension is applied to the unmelted sheet end portion, and unnecessary tension due to conveyance is not applied to the pattern formed sheet central portion. Optical strain does not occur due to the take-up tension of conveyance.

The conveying jig 7 may be arranged at a position immediately after molding, but the conveying jig may be arranged so as to hold the end portion during heating or during molding. The molded resin sheet may be cooled by providing a cooling blower 8. Further, after cooling, the product can be manufactured in a desired form such as cutting, laminating with another sheet, or winding on a roll.

[0018]

EXAMPLES The present invention will be described more specifically below with reference to examples. The present invention is not limited to this embodiment.

Example 1 An acrylic sheet (thickness 0.4 mm, width 410 mm) was used as the material of the transparent substrate of the optical card. A total of four heating infrared lamps (250 W) in the heating chamber were arranged above and below at an irradiation distance of 15 cm. As a light-shielding plate, a Cu plate was arranged at a position of the sheet edge portion 90 mm so that the infrared lamp was not irradiated.

A pressure roll was prepared by forming a mirror surface with a width of 230 mm on a cooling roll having a diameter of 300 mm and a roll surface length of 500 mm. Similarly, a forming roll having a diameter of 300 mm and a roll surface length of 500 mm has a thickness of 0.2 mm and a width of 230 mm.
A Ni electroformed sheet-shaped stamper with a pattern of mm was screwed to prepare a stamper roll.

A groove pattern was formed on the heated resin sheet at a rate of 15 m / min using both rolls.
A total of 15 sets of rolls having a diameter of 50 mm and a roll surface length of 70 mm were installed above and below both ends of the resin sheet to form a conveyance jig, and the resin sheet was conveyed at 15 m / min. Seat center 230
mm has good transferability on both the mirror surface and the pattern, and has a thickness of 0.
A 4 mm acrylic resin sheet was obtained.

Example 2 A polycarbonate resin sheet was prepared in the same manner as in Example 1.
It was molded and conveyed at a speed of m / min. The 230 mm center portion of the resin sheet has good transferability on both the mirror surface and the pattern, and the birefringence after the sheet is drawn is 5 nm or less and the thickness is 0.4 mm.
A polycarbonate resin sheet of was obtained.

[0023]

As described above, according to the present invention,
When the resin sheet is heated, the resin sheet is heated by using a light shielding plate so that the end portion of the resin sheet is not heated, and the end portion of the resin sheet is conveyed by holding the end portion when the resin sheet is conveyed. It has become possible to manufacture a substrate for an optical recording medium which is free from distortion and deformation of parts, has good transferability and thickness accuracy, and has particularly little optical distortion.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of an apparatus used in a method for manufacturing an optical recording medium substrate of the present invention.

FIG. 2 is a schematic view showing an example of portions of a light shielding plate, a molding roll and a carrying jig used in the method for manufacturing an optical recording medium substrate of the present invention.

FIG. 3 is an explanatory view showing a conventional method for manufacturing a substrate for an optical recording medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermoplastic resin sheet 2 Heating chamber 3 Infrared lamp 4 Light-shielding plate 5 Stamper roll 6 Pressure roll 7 Transfer jig 8 Cooling blower 9 Roller 10 Pulling machine 12 Die-cutting roll 13 Stamper

Claims (1)

[Claims] 1. A thermoplastic resin sheet is heated, and the pattern is transferred and formed by embossing using a stamper roll provided with a stamper having a preformatted pattern formed on the roll surface of the thermoplastic resin sheet and a pressure roll. In the method of manufacturing a substrate for an optical recording medium, when the thermoplastic resin sheet is heated, a pattern is transferred without heating the resin sheet end, and the resin sheet is conveyed while holding the resin sheet end. A method for manufacturing an optical recording medium substrate, comprising: