JPH11198201A - Preparation of optical disc and apparatus for preparing substrate for optical disc - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preparing an optical disc which has a uniform thickness and excellent optical characteristics and an apparatus for preparing a substrate for an optical disc. SOLUTION: When a resin is injected into a cavity 24 formed of a fixed side mold 9 and a movable side mold 10 and the resin in the cavity 24 is compressed by means of a movable side core part 19 forwarding into the cavity 24 by means of a core compressing piston 54 to prepare a substrate for an optical disc, the parallelism between the core compressing piston 54 before forwarding and a fixed side platen 2 for fixing the fixed side mold 9 is regulated in less than 10 μm to mold the base sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk manufacturing method and an optical disk substrate manufacturing apparatus. More specifically, for example, an optical disc substrate formed of a transparent thermoplastic resin such as a polycarbonate resin used for a phase change rewritable optical disc, a magneto-optical disc, a write-once optical disc, or a polymethyl methacrylate resin was used. The present invention relates to an optical disk manufacturing method and an optical disk substrate manufacturing apparatus.

[0002]

2. Description of the Related Art An optical disk has a structure in which recording and reproducing films are formed on a transparent substrate surface, and a laser passes through the inside of the substrate to read and write signals. For this reason, the influence of the thickness of the substrate on the signal is large. In recent years, as seen in DVDs, with the increase in density, techniques for reducing signals and laser light have been advanced. At this time, in order to reduce the influence of warpage of the substrate on signals, a conventional CD or the like has Thinner substrates are required. That is, the influence of the substrate thickness on the distortion of the laser beam is regarded as more important, and a substrate having a smaller warpage and a more uniform thickness is desired as the thickness is reduced.

[0003] For this reason, the molding of the optical disk substrate requires
Usually, an injection compression molding method capable of molding a substrate having a more uniform thickness than injection molding, for example, an injection press method, a Rollins method, a micromolding method, or the like is employed. Above all, the micromolding method in which the movable side core portion is advanced by a core compression piston after a predetermined amount of resin is filled in the cavity of the mold to compress and mold the resin in the cavity is used for the movable side core portion. This is a preferable molding method because the compression stroke amount and the like can be precisely controlled relatively easily.

In order to form a substrate having a uniform thickness using the above-mentioned injection compression molding method or injection molding method, for example, the parallelism between the movable mold and the fixed mold, or each mold is used. It is important to adjust the parallelism and the like between the movable platen and the fixed platen to which the plate is attached within an appropriate range.
-363218).

[0005]

However, in order to form a substrate having a uniform thickness by the micromolding method, the present inventor has proposed a core compression method in which a movable core portion for compressing resin in a cavity is advanced. While adjusting the parallelism between the piston and the fixed side platen to a predetermined range,
The present inventors have found that it is extremely important to maintain appropriate parallelism with the fixed-side platen even while the core compression piston advances, and have completed the present invention.

It is an object of the present invention to provide a method for manufacturing an optical disk capable of adjusting the parallelism between a core compression piston and a fixed-side platen within an appropriate range and exhibiting excellent optical characteristics with a uniform thickness. .

[0007]

In order to solve the above-mentioned problems, a method of manufacturing an optical disk according to the present invention comprises: injecting a resin into a cavity formed by a fixed mold and a movable mold;
In manufacturing the optical disc substrate by compressing the resin in the cavity with the movable core portion advanced into the cavity by the core compression piston, a fixed platen for attaching the core compression piston and the fixed mold before advancement. And adjusting the parallelism to 10 μm or less to form the substrate.

It is preferable that the parallelism between the core compression piston and the fixed side platen be kept within 20 μm while the core compression piston is moving forward.

Preferably, the parallelism between the fixed platen and the movable platen on which the movable mold is mounted is adjusted within 30 μm.

The method for manufacturing an optical disk according to the present invention is particularly suitable for forming a thin substrate having a thickness of 1 mm or less.

An apparatus for manufacturing an optical disk substrate according to the present invention injects a resin into a cavity formed by a fixed mold and a movable mold, and advances the resin in the cavity into the cavity by a core compression piston. In an apparatus for manufacturing an optical disc substrate by compressing the movable side core portion, the parallelism between the core compression piston before advancing and the fixed side platen for mounting the fixed side mold is within 10 μm. Consist of things.

In the optical disk manufacturing method and the optical disk substrate manufacturing apparatus described above, the parallelism between the core compression piston and the fixed platen before advancement is adjusted to within 10 μm, so that the movable side advanced by the core compression piston. Since the parallelism between the core and the fixed mold attached to the fixed platen is within the optimal range, excessive thickness unevenness on the molded substrate is prevented, and a uniform thickness substrate Can be obtained.

Further, by adjusting the parallelism between the core compression piston and the fixed-side platen before advancement to within 10 μm, the parallelism between the core compression piston and the fixed-side platen during the advancement of the core compression piston can be easily achieved. Can be kept within 20 μm.

In order to set and control the parallelism between the core compression piston and the fixed-side platen within the above range before and during the forward movement, the parallelism between the fixed-side platen and the movable-side platen must be 30 μm. It is preferable to adjust within. If it exceeds 30 μm, it becomes difficult to keep the parallelism between the core compression piston and the fixed platen within the above range.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the method for manufacturing an optical disk and the apparatus for manufacturing an optical disk substrate according to the present invention will now be described with reference to the drawings. FIG.
1 shows an optical disk substrate manufacturing apparatus according to the present invention. In FIG. 1, reference numeral 1 denotes a part of an injection compression molding machine. The injection compression molding machine 1 has a mold clamping mechanism and an injection mechanism (not shown). The stationary platen 2 of the mold clamping mechanism and the pressure receiving plate 3 are connected by a tie bar 4. A movable platen 5 is slidably mounted on the tie bar 4. A clamping piston 7 in a clamping cylinder 6 is connected to the movable platen 5. The movable platen 5 slides in the left-right direction in FIG. 1 by reciprocating the mold clamping piston 7 in the mold clamping cylinder 6.

The mold 8 is composed of a fixed mold 9 and a movable mold 10 with a mold division plane (PL) as a boundary. The fixed body 11 of the fixed mold 9 is fixed to a fixed mounting plate 12.
A fixed type guide ring 13 fixed to 2 is provided. A resin filling hole, a so-called spool 14, which forms a spool 14, is provided at the center of the fixed mold 9, and a resin runner, a so-called gate 16, is formed at one end thereof. . A fixed side bush 17 is concentrically fixed around the spool bush 15, and its tip is formed as a die 18 for gate cutting.

The movable core 19 of the movable mold 10 includes
A disk-shaped stamper 20 is held on the inner periphery by an inner stamper holder 21. A cavity ring 22 provided on the outer edge of the fixed die body 11 is urged by a spring (not shown) on the outer periphery of the stamper 20.

The center of the movable side core portion 19 is formed around an ejector pin 25 for projecting the formed spool 14, a gate cut punch 23 for punching the formed gate 16, and a cavity 24 formed in the cavity 24. An ejector sleeve 26 that projects a substrate to be ejected by the action of a floating mechanism (not shown) of an ejector pin 25 is concentric with the inner stamper holder 21 and
The ejector pin 25, the gate cut punch 23, and the ejector sleeve 26 are combined so as to be able to move forward and backward in the axial direction.

A movable guide ring 28 on the outer periphery of the movable core 19 is mounted on a movable mounting plate 29. An adjustment spacer 30 for adjusting the compression stroke δ of the movable core 19 is provided between the movable core 19 and the movable mounting plate 29.

A contact ring 3 is provided on the outer periphery of the movable side core portion 19.
1 is provided integrally with the movable side core portion 19, and comes into contact with the cavity ring 22 at the time of mold clamping. The fixed die 9 and the movable die 10 are formed by contacting the tip of the fixed guide ring 13 with the tip of the movable guide ring 28 and the cavity ring 22 with the contact ring 31.
A cavity 24 is formed as a predetermined space therebetween.
Then, the cavity 24 is filled with a molten resin, cooled, and a substrate for an optical disk is formed.

A core compression cylinder 41 and an ejector cylinder 4 are provided at the connection between the movable side platen 5 and the mold clamping piston 7.
2 and the punch cylinder 51 are mounted concentrically.
By moving the core compression piston 54 of the core compression cylinder 41 forward and backward by core compression control means (not shown), the mold cavity 24 is moved through the movable core portion 19.
A compressive force can be applied to and released from the resin inside.

Further, the ejector cylinder 42 is operated by a hydraulic circuit (not shown) and its control device (not shown), and the ejector pin 25 and the ejector sleeve 26 are respectively advanced and ejected via an ejector rod 50.
Can be retracted. Further, the punch cylinder 5
1 is a hydraulic circuit (not shown) and its control device (not shown)
And the gate cut punch 23 can be moved forward and backward through the punch piston 53.

In the injection compression molding machine 1 of this embodiment, the parallelism between the core compression piston 54 and the fixed-side platen 2 before advancement (in a stationary state) is adjusted to be within 10 μm. The parallelism between the core compression piston 54 and the fixed-side platen is determined by the compression molding machine 1 from the mold 8 and the plate 12,
29, the distance between the piston 54 and the platen 2 can be measured at several points using, for example, a micrometer or the like, and can be calculated from the measured values. And the parallelism is 1
When the thickness exceeds 0 μm, the fixed platen 2 and
The adjustment can be performed by interposing a shim or the like between the platen 2 and a mounting plate (not shown).

In the injection compression molding machine 1, a nozzle (not shown) on the side of the injection mechanism comes into contact with the nozzle touch portion 52, and the molten resin is injected into the cavity 24 from the nozzle.
When the cavity 24 is filled with a predetermined amount of resin, the movable side core portion 19 is moved by the core compression piston 54.
Is advanced into the cavity 24 so that the resin in the cavity 24 is compressed. At this time, in the present embodiment, since the parallelism between the core compression piston 54 and the fixed-side platen 2 before the advance is adjusted with high accuracy within 10 μm, the core compression while the core compression piston 54 is advancing. The parallelism between the piston 54 and the fixed-side platen 2 is easily kept within 20 μm.

The parallelism between the core compression piston 54 and the stationary platen 2 while the core compression piston 54 is moving forward is determined by removing the mold 8 and the plates 12 and 29 from the injection compression molding machine 1. Attach a micrometer to several points of the fixed side platen 2 and the core compression piston 5
4 can be measured by monitoring it while moving it forward by manual operation or the like.

The parallelism between the fixed platen 2 and the movable platen 5 of the injection compression molding machine 1 is adjusted so as to be within 30 μm.

The substrate manufactured by the method for manufacturing an optical disk according to the present invention can be formed, for example, from a resin composition containing polycarbonate as a main component. Polycarbonates are transparent, for example, obtained by the reaction of a dihydric phenol with a carbonate precursor. Examples of the dihydric phenol include hydroquinone, 4,4'-dioxydiphenyl, bis (hydroxyphenyl) alkane,
Bis (hydroxyphenyl) cycloalkane, bis (hydroxyphenyl) ether, bis (hydroxyphenyl) ketone, bis (hydroxyphenyl) sulfide,
Bis (hydroxyphenyl) sulfone and substituted products thereof such as lower alkyl and halogen can be used.

It is necessary that the viscosity average molecular weight of the polycarbonate resin composition is in the range of 13,000 to 18,000. If it is less than 13,000, the strength of the formed substrate becomes insufficient, and practical strength as an optical recording medium cannot be obtained. On the other hand, when it exceeds 18,000, the fluidity of the resin at the time of molding is reduced, and problems such as transferability and optical distortion are likely to occur.

A predetermined recording layer is provided on the information surface of the formed substrate. For the recording layer, first, a protective layer is provided on the substrate,
It may be formed thereon. Various layers such as a protective layer and a reflective layer may be further provided on the formed recording layer.

In the recording layer, for example, Te-Ge-Sb
-Pd alloy, Te-Ge-Sb-Pd-Nb alloy, Nb
-Ge-Sb-Te alloy, Pt-Ge-Sb-Te alloy, Ni-Ge-Sb-Te alloy, Ge-Sb-Te alloy, Co-Ge-Sb-Te alloy, In-Sb-Te alloy, In -Se alloys and alloys containing these as main components are used. In particular, Te-Ge-Sb-Pd alloy, T
An e-Ge-Sb-Pd-Nb alloy is preferable because it hardly deteriorates even when recording / erasing / reproducing is repeated and has excellent thermal stability. These alloys are formed on the first protective layer provided on the substrate, for example, by sputtering,
A recording layer is formed.

[0031]

Examples 1 to 3 and Comparative Example 1 Parallelism between the fixed platen 2 and the movable platen 5 (parallelism between the platens), and parallelism between the core compression piston 54 and the fixed platen 2 before advancing. Table 1 shows the parallelism between the core compression piston 54 and the fixed-side platen 2 while the core compression piston 54 is moving forward (core parallelism while the core compression piston 54 is moving forward). , And a substrate having a thickness of 0.6 mm was molded. The obtained substrate was measured for uneven thickness. The results shown in Table 1 were obtained.

As is apparent from Table 1, when the parallelism between the core compression piston and the fixed plate and the parallelism between the platens before and during the advance are adjusted within the ranges disclosed in the present invention (implementation). In Examples 1 to 3, the thickness unevenness of the formed substrate could be significantly reduced.

[0033]

[Table 1]

[0034]

As described above, according to the optical disk manufacturing method and the optical disk substrate manufacturing apparatus of the present invention, the parallelism between the core compression piston and the fixed platen before and during advancement is reduced. Since the adjustment is made within the optimum range, it is possible to manufacture an optical disk substrate having a small thickness unevenness.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus for manufacturing an optical disk substrate according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Part of injection compression molding machine 2 Fixed platen 3 Pressure receiving plate 4 Tie bar 5 Movable platen 6 Mold clamping cylinder 7 Mold piston 8 Mold 9 Fixed mold 10 Moving mold 11 Fixed mold body 12 Fixed mold attachment Plate 13 Fixed type guide ring 14 Spool 15 Spool bush 16 Gate 17 Fixed type bush 18 Dice 19 Movable core 20 Stamper 21 Inner stamper holder 22 Cavity ring 23 Gate cut punch 24 Cavity 25 Ejector pin 26 Ejector sleeve 28 Movable side guide ring 29 Movable side mounting plate 30 Adjustment spacer 31 Contact ring 41 Core compression cylinder 42 Ejector cylinder 50 Ejector rod 51 Punch cylinder 53 Punch piston 54 Core compression piston

Claims (8)

[Claims] 1. A resin is injected into a cavity formed by a fixed mold and a movable mold, and the resin in the cavity is compressed by a movable core portion advanced into the cavity by a core compression piston. A method for manufacturing an optical disk, comprising: adjusting a parallelism between the core compression piston before advancement and a fixed platen for mounting a fixed mold within 10 μm to form a substrate when manufacturing an optical disk substrate. . 2. The method according to claim 1, wherein the parallelism between the core compression piston and the fixed platen is maintained within 20 μm while the core compression piston is moving forward. 3. The method for manufacturing an optical disk according to claim 1, wherein the parallelism between the fixed platen and the movable platen on which the movable mold is mounted is adjusted within 30 μm. 4. The method for manufacturing an optical disk according to claim 1, wherein a substrate having a thickness of 1 mm or less is formed. 5. A resin is injected into a cavity formed by a fixed mold and a movable mold, and the resin in the cavity is compressed by a movable core portion advanced into the cavity by a core compression piston. An apparatus for manufacturing an optical disk substrate, wherein the parallelism between the core compression piston before advancing and a fixed platen for mounting a fixed mold is within 10 μm. 6. The optical disk substrate manufacturing apparatus according to claim 5, wherein the parallelism between the core compression piston and the fixed side platen is maintained within 20 μm while the core compression piston is moving forward. 7. The apparatus for manufacturing an optical disc substrate according to claim 5, wherein the parallelism between the fixed platen and the movable platen for attaching the movable mold is within 30 μm. 8. The apparatus for manufacturing an optical disk substrate according to claim 5, wherein the substrate is formed to a thickness of 1 mm or less.