JPH11213457A - Manufacturing device for substrate for optical disk, manufacturing method of substrate for optical disk and optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing device and manufacturing method of a substrate for an optical disk capable of stably molding the substrate of high quality over the long period of time by preventing the distortion and damage, etc., of a stamper. SOLUTION: In this manufacturing device of the substrate for the optical disk provided with a die for injection molding on which the stamper 9 is mounted for which the stamper 9 is fixed to the die so as to be clamped between the die and a cavity ring 11, the clearance of 10-20 m is provided between the opposite surfaces of the stamper 9 and the cavity ring 11. Also, the manufacturing method and the optical disk manufactured by the method are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an apparatus and a method for manufacturing an optical disk substrate. More specifically, for example, a phase change rewritable optical disk, a magneto-optical disk,
The present invention relates to an apparatus for manufacturing an optical disk substrate formed of a transparent thermoplastic resin such as a polycarbonate resin or a polymethyl methacrylate resin used for a write-once optical disk and a method of manufacturing an optical disk substrate using the apparatus. is there.

[0002]

2. Description of the Related Art When an optical disk substrate, which is a base material of an optical disk such as a CD, a phase change optical disk, a magneto-optical disk, a DVD, and a laser disk, is formed by the injection molding machine, the gold mounted on the injection molding machine is used. The mold is equipped with a donut-shaped metal plate called stamper on which predetermined signals and grooves necessary for the optical disk are formed in advance, and the mold is filled with molten resin so that the signals and grooves on the stamper are accurately placed on the substrate. And the substrate is molded. Therefore, in order to mold a high quality optical disc substrate, it is important to accurately position the stamper in the cavity of the mold.

[0003] Therefore, when fixing the stamper to the mold, a jig for regulating the inner diameter of the stamper called an inner stamper holder is passed through the center hole of the stamper, and the regulating jig is inserted into the mold. The center of the mold and the center of the stamper are aligned, and the outer periphery of the stamper is fixed to the mold by a cavity ring (peripheral stamper retainer) so that it is sandwiched between the mold and the mold. A method of adsorbing and fixing a stamper to a mold by the suction device is adopted.

[0004]

However, when the stamper is fixed in the mold as described above and the molding of the substrate is repeated, if the fixation of the stamper to the mold is insufficient, the misalignment of the stamper is caused. For example, there is a problem that the amount of eccentricity of the substrate is liable to change and increase. On the other hand, if the stamper is too tightly fixed to the mold, the roundness of the substrate will increase due to the load imposed on the stamper, and the radial acceleration will increase due to the local distortion of the roundness. However, there is a problem that the stamper is easily damaged.

Here, the term "eccentricity" refers to the amount of deflection of the recording groove of the formed substrate at a certain measurement radius position by one round (36
Radial runout), a virtual circle is calculated from the measured value, and the distance between the rotation center of the substrate and the center of the virtual circle is referred to. Further, “roundness” refers to a difference in radius between a concentric circle circumscribing the virtual circle and a concentric circle circumscribing the virtual circle. The “radial acceleration” is the radial acceleration of a disk groove or a pit row, and is the radius acceleration.
It refers to the second-order differential of l runout data.

An object of the present invention is to reduce the amount of eccentricity, roundness, and radial acceleration of a substrate by suppressing displacement, distortion, and damage of a stamper in a mold when the substrate is repeatedly formed. An object of the present invention is to provide a manufacturing apparatus and a manufacturing method of an optical disc substrate that can be stably molded for a long period of time while keeping the optical disc substrate within a predetermined management value.

[0007]

In order to solve the above problems, an apparatus for manufacturing an optical disk substrate according to the present invention has an injection mold having a stamper mounted thereon, and the stamper is connected to the mold by a cavity ring. In a manufacturing apparatus for an optical disc substrate fixed to a mold so as to be sandwiched between the stamper and a cavity ring, 10 to 3
It is characterized by having a clearance of 0 μm, preferably 15 to 25 μm.

If the clearance is smaller than 10 μm, the distortion of the stamper cannot be sufficiently absorbed, and the roundness of the substrate may increase. On the other hand, if it is larger than 30 μm, the fixation of the stamper may be insufficient, and burrs may be generated on the substrate or the stamper may be damaged.
That is, in the present invention, by setting the clearance in the optimum range, the displacement of the stamper in the mold can be suppressed, and the distortion can be absorbed while preventing the stamper from being damaged. The eccentricity and roundness of the substrate can be kept within appropriate ranges.
A high-quality substrate can be stably formed over a long period of time.

Although the shape of the cavity ring is not particularly limited, for example, at least a part of the cavity ring is formed so that a leg that can be fitted to the mold and an outer peripheral portion of the stamper are sandwiched between the mold. It is possible to adopt a shape having a hook-shaped cross section with the arm portion facing one surface of the stamper. In this case, the clearance may be provided between the arm and the surface of the stamper facing the arm on the cavity ring side, and the cavity ring does not need to be on the stamper side.

According to another aspect of the present invention, there is provided a method of manufacturing a substrate for an optical disk, comprising the steps of: mounting a stamper on a mold for injection molding; and holding the stamper between the mold using a cavity ring. When molding the optical disc substrate by injecting a resin into the mold so that the stamper and the cavity ring face each other,
A method of providing a clearance of 0 to 30 μm, preferably 15 to 25 μm, and fixing the stamper to a mold while absorbing distortion of the stamper by the clearance.

An optical disk according to the present invention uses an optical disk substrate manufactured by such a manufacturing method.

When the method of manufacturing a substrate for an optical disk according to the present invention is carried out, it is preferable that the stamper be sucked into a mold by suction, and the suction operation is performed intermittently during operation of the injection molding machine. preferable.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an apparatus and a method for manufacturing an optical disk substrate according to the present invention will be described below with reference to the drawings. FIG. 1 shows the mold peripheral portion of the optical disk substrate manufacturing apparatus according to each embodiment of the present invention when the cavity ring is provided on the side of the stamper, and FIG. 2 shows the case where the cavity ring is provided on the side opposite to the stamper. I have. In the figure, reference numeral 1 denotes an optical disk substrate manufacturing apparatus. The manufacturing apparatus 1 has a mold clamping mechanism and an injection mechanism (not shown). A tie bar (not shown) is connected to the fixed side platen 2 of the mold clamping mechanism, and the movable side platen 3 is slidably mounted on the tie bar.

The mold 4 includes a fixed mold 5 and a movable mold 6. The fixed mold 5 has a movable mold 6 on the fixed platen 2.
Is mounted on the movable-side platen 3, and the movable mold 6 slides with the sliding of the movable-side platen 3, so that the mold 4 is opened and closed.

A spool bush 8 forming a spool 7 is provided substantially at the center of the fixed die 5.

A stamper 9 is attached to the movable mold 6. The stamper 9 is fixed so as to be sandwiched between an inner stamper retainer 10 that penetrates through the center hole of the stamper 9 and is inserted into the movable die 6 and an outer peripheral portion of the stamper 9 between a cavity surface of the movable die 6. A predetermined position is fixed by the cavity ring 11.

The cavity ring 11 has a leg 13 which can be fitted to the movable mold 6 in FIG. 1 and a fixed mold 5 in FIG. 9 is formed of a member having a hook-shaped cross section and having an arm portion 14 facing one surface 9a (the surface on the cavity ring side of the stamper 9). A distance between the stamper-side surface 14a of the arm 14 and the surface 9a of the stamper 9 is 10 to 30 μm.
m clearance δ is provided.

The stamper 9 can be attracted to the movable mold 6 by suction by a suction device (not shown). The suction operation by the suction device is performed intermittently during operation of the device 1.

Using the optical disk substrate manufacturing apparatus 1 according to the present embodiment, an optical disk substrate manufacturing method of the present invention is performed as follows. First, the movable mold 6
After the mold is closed by sliding, the nozzle 1 on the injection mechanism side
After the molten resin is injected and filled into the cavity of the mold 4 from the mold 2 and cooled while applying a holding pressure, the substrate formed by opening the mold and being molded by an ejector (not shown) is peeled from the cavity, and the stamper 9 is formed. The substrate on which the information is transferred is formed.

In the apparatus for manufacturing an optical disk substrate according to the present embodiment, a clearance δ is provided between the surface 9a of the stamper 9 and the surface 14a of the cavity ring 11, ie, between the opposing surfaces of the stamper 9 and the cavity ring 11. When the stamper 9 is fixed by the cavity ring 11 or when a resin is injected, a load is applied to the stamper 9 to cause distortion, the distortion is absorbed by the clearance δ. Therefore, it is possible to prevent the stamper 9 from being damaged while correcting the position and posture of the stamper 9 in the mold 4. Further, in the present embodiment, the stamper 9 is attracted to the mold 4 by suction of the suction device, but the suction operation of the suction device is performed intermittently during the operation of the device 1. Has become. For this reason, if the suction operation is performed intermittently at the timing when the load on the stamper 9 increases, for example, when the resin is injected, the distortion can be absorbed while preventing the displacement of the stamper 9 and the like. Can be.

The substrate manufactured by the apparatus and method for manufacturing an optical disk substrate 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, and bis (hydroxyphenyl) Sulfides, bis (hydroxyphenyl) sulfones, and their substituted compounds such as lower alkyl and halogen can be used. In addition, various additives, for example, a phosphorus-based stabilizer may be added.

The viscosity average molecular weight of the polycarbonate resin composition is preferably 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 it is difficult to obtain practical strength as an optical disk. 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. A particularly desirable recording film composition is, for example, in the range represented by the following formula, from the viewpoint of excellent thermal stability and repetition stability. M _z (Sb _x Te _(1-X) ) _1-yz (Ge _0.5 Te _0.5 )
_y 0.35 ≦ x ≦ 0.5 0.20 ≦ y ≦ 0.50 ≦ z ≦ 0.05 where M is at least one metal selected from palladium, niobium, white stripe, silver, stripe, cobalt, Sb represents antimony, Te represents tellurium, and Ge represents germanium. Also,
x, y, z and numerals represent the number of atoms of each element (the number of moles of each element). In particular, palladium and niobium preferably contain at least one kind. In this case, z is 0.
It is preferably at least 0005. These alloys are applied on a protective layer provided on a substrate by, for example, sputtering to form a recording layer.

[0025]

EXAMPLES Example 1, Comparative Examples 1-2 The clearance between the opposing surfaces of the stamper and the cavity ring was set to 5, 20, and 30 (μm), and the diameter was 130 mm and the thickness was in a state where the suction operation by the suction device was stopped. 1.2
The optical disk substrate having a thickness of 1 mm was continuously molded, and the damage state of the stamper and burrs, roundness, and radial acceleration of the molded substrate were examined. Table 1 shows the results.

Example 2 A substrate was continuously formed under the same conditions as in Example 1 except that the suction operation of the suction device was performed intermittently during the forming process, and the eccentricity of the formed substrate was measured. This was compared with the eccentricity of the substrate of Example 1. Table 2 shows the results. Note that the amount of eccentricity is substantially equal to one half of the PP value indicating the difference between the maximum value and the minimum value in the above-described Radial runout, so that PP
The eccentricity can be estimated using the value as a guide. Table 2 shows the PP values.

As apparent from Table 1, when the clearance between the opposing surfaces of the stamper and the cavity ring is not set in the optimum range (10 to 30 μm) disclosed in the present invention (Comparative Examples 1 and 2), the stamper is not used. Defects such as damage and an increase in roundness (or occurrence of burrs on the substrate) are observed. However, when the clearance between the opposing surfaces is set within an optimum range (Example 1), stamper damage is prevented. It can be seen that high-quality substrates can be stably and continuously formed. As is clear from Table 2, if the suction operation is performed intermittently during the molding process (Example 2), PP
The value, that is, the amount of eccentricity can be reduced at the same time.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

As described above, according to the apparatus and method for manufacturing an optical disk substrate of the present invention, an appropriate clearance (10 to 30 μm) is set between the opposing surfaces of the stamper and the cavity ring. , Can properly absorb the distortion of the stamper and prevent damage,
High quality substrates can be stably formed continuously. In addition, if the suction operation is performed intermittently during the molding process, the amount of eccentricity of the substrate can be reduced, so that a higher quality substrate can be obtained.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of an apparatus for manufacturing an optical disk substrate according to an embodiment of the present invention.

FIG. 2 is a partial sectional view of an apparatus for manufacturing an optical disc substrate according to another embodiment of the present invention.

FIG. 3 is an enlarged partial sectional view of a cavity ring of the apparatus of FIG. 1;

[Description of Signs] 1 Injection molding apparatus for optical disk substrate 2 Fixed side platen 3 Movable platen 4 Mold 5 Fixed type 6 Movable type 7 Spool 8 Spool bush 9 Stamper 9a Surface on the cavity ring side of stamper 10 Inner stamper retainer 11 Cavity ring 12 Nozzle 13 Leg 14 Arm 14a Surface of arm on stamper side δ Clearance

Claims (7)

[Claims] An apparatus for manufacturing an optical disc substrate, comprising: an injection mold having a stamper mounted thereon, wherein the stamper is fixed to the mold so as to be sandwiched between the mold and the mold by a cavity ring. An apparatus for manufacturing an optical disk substrate, wherein a clearance of 10 to 30 μm is provided between opposing surfaces of a cavity ring. 2. A hook between at least a part of the cavity ring and an arm facing one surface of the stamper so as to sandwich a leg fitted to the mold and an outer peripheral portion of the stamper between the mold and the mold. 2. The optical disk substrate manufacturing apparatus according to claim 1, wherein the clearance is provided between the arm portion of the cavity ring and a surface of the stamper facing the cavity ring side, the clearance being provided. 3. The apparatus for manufacturing an optical disk substrate according to claim 1, wherein a clearance between the opposing surfaces of the stamper and the cavity ring is 15 to 25 μm. 4. A stamper is mounted on an injection molding die,
Using a cavity ring, the stamper is fixed to a mold so as to be sandwiched between the mold and a resin. The resin is injected into the mold to form an optical disc substrate. A method of manufacturing a substrate for an optical disk, wherein a clearance of 10 to 30 μm is provided to the stamper, and the stamper is fixed to a mold while absorbing distortion of the stamper by the clearance. 5. The method of manufacturing an optical disc substrate according to claim 4, further comprising: adsorbing the stamper by suction, and performing the suction operation intermittently during operation of the injection molding machine. 6. The method for manufacturing an optical disk substrate according to claim 4, wherein a clearance between the opposing surfaces of the stamper and the cavity ring is 15 to 25 μm. 7. An optical disk using an optical disk substrate manufactured by the manufacturing method according to claim 4. Description: