JP2003154557A - Die device for manufacturing disk-like base material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a die device to form a disk-like base material for an optical disk having a central hole in such a manner that a resin layer having a uniform thickness distribution may be formed. SOLUTION: This die device 30 holds a stamper 10 to a movable die 34 by a suction means 36 in the cavity 31. For the stamper 10, a through hole 10A of which the diameter is smaller than the central hole of the optical disk is formed. Then, a die dividing line does not exist at a section corresponding to a range from the outer periphery of the stamper 10 to the through hole 10A of the information recording surface 12A of the disk-like board material 12 which is formed by injection-molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold device for manufacturing a disc-shaped substrate material.

[0002]

2. Description of the Related Art Generally, CD (Compact Disc) and D
For a disc-shaped optical recording medium (optical disc) such as a VD (Digital Versatile Disc), a stamper formed by a mastering process is mounted in a mold installed in an injection molding machine, and an area serving as an information recording surface is injection-molded. By forming a disc-shaped substrate material made of resin, a recording layer or the like that can be recorded or a reflective layer that is provided to make it reproducible is formed on this, and a protective layer made of resin is provided on it. Are manufactured.

More specifically, in the manufacture of optical discs, a stamper is attached in the cavity of a mold during the injection molding of a substrate, and the unevenness of the surface is transferred to the surface of the disc-shaped substrate material to form an information recording surface. Area is formed, and after a reflective film, a recording layer configured to be recordable, and the like are further formed, in the next step, a resin protective layer and the like are formed by, for example, a spin coat method to obtain a finished product. .

These optical disks record and / or reproduce information by rotating while irradiating a predetermined laser beam through the disk-shaped substrate material.

Further, the CD or DVD is usually formed with a central hole (here, diameter 15 mm) for use in positioning the optical disk at the time of recording and / or reproducing at the central position thereof.

Further, the stamper mounted in the mold as described above usually has a through hole larger than the central hole of the optical disk. By utilizing this through hole, positioning and melting in the mold are performed. It is used for the purpose of injecting materials. This through hole has a diameter of 20 to
It is 38 mm.

On the other hand, recently, for example, Japanese Patent Laid-Open No. 8-23563.
As disclosed in Japanese Unexamined Patent Publication No. 8 (1998), a support layer (protective layer) that does not need to transmit light, that is, does not require an optical thickness, is formed as a disk-shaped substrate material (substrate) to be thick by injection molding. On the information recording surface side of the substrate, after forming a reflection film provided for making information reproducible or a recording layer made recordable, a transparent resin capable of transmitting recording / reproducing laser light thereon. Attention has been paid to light produced by a production method in which a light-transmitting layer of layers is formed.

In the manufacture of such an optical disc, during the injection molding of the substrate, as shown in FIG. 6, the center of the substrate 2 is solidified in the mold apparatus 1 in the gate during the injection molding. By separating and removing the sprue runner 3, a circular center hole 2A is opened in the central portion to form a disk-shaped substrate material, and further, after forming the reflective film and the recording layer configured to be recordable, In the process, a protective layer made of a resin or a light transmitting layer made of a light transmitting resin is formed by, for example, a spin coating method to obtain a finished product.

In the mold apparatus 1, the substrate 2 has a cavity 6 between an upper fixed mold 4 and a lower movable mold 5.
The stamper 7 is held in the fixed mold 4 via a stamper holder 8 here. Reference numeral 9 in FIG. 6 indicates a sprue bush, and molten resin is injected into the cavity 6 from the sprue bush 9.

Since the die unit 1 has the above-mentioned structure, the information recording surface 2C on the stamper 7 side of the substrate 2 is formed.
A so-called mold parting line, which is a boundary line between the sprue bush 9 and the stamper holder 8 and a boundary line between the stamper holder 8 and the stamper 7, is generated at.

[0011] Usually, in the mold parts forming the information recording surface side of the substrate, when the stamper is arranged on the fixed mold side, a sprue bush, a stamper holder, a stamper (mirror surface), an outer peripheral ring ( (May not be provided) are arranged concentrically from the center of the mold.

Further, when the stamper is arranged on the movable mold side, the ejection pin, the cut punch, the ejection sleeve, the stamper holder, the stamper (mirror surface), and the outer peripheral ring (which may not be provided) are similarly formed in the die. They are arranged concentrically from the center.

Therefore, in any of the above cases, a plurality of concentric mold dividing lines 8A, on the information recording surface side of the substrate,
9A and step 8B appear.

Further, the center hole 2A of the substrate 2 is substantially the same as the maximum diameter of the sprue runner 3, while the stamper 7
The inner diameter of the positioning hole 7A at the center is substantially the same as the outer diameter of the stamper holder 8 on the outside of the sprue bush 9, and therefore is considerably larger than the central hole 2A.

Further, as one of the characteristic manufacturing methods of the protective layer or the light transmitting layer of the above optical disk,
As disclosed in Japanese Unexamined Patent Publication No. 10-249264, a protective layer (resin) is provided by installing a lid-like member that covers the center hole of an optical disc, and spin-coating a resin on the lid-like member and spreading and curing the resin over the entire optical disc. There is a manufacturing method of forming a layer). In this method, since it is easy to control the layer thickness of the resin layer in the coating surface so that the resin layer has a substantially uniform thickness in the radial direction, a light transmitting layer is formed.
It is also applicable to Japanese Patent No. 638.

[0016]

As described above, the substrate 2
When a mold dividing line is generated on the information recording surface 2C side of the substrate 2
When a light-transmitting layer made of a light-transmitting resin is formed from the central part of the above by a spin coating method, the coating is defective due to the mold dividing line. Specifically, due to the mold parting line, meteor streaks are generated during spin coating, and the highly accurate thickness required for the light transmitting layer cannot be formed uniformly.

Further, as described above, when the central hole of the substrate is closed by the lid-like member during the spin coating, the light transmissive resin usually flows down from the lid-like member onto the surface of the disk-like substrate material. Therefore, it is easy to cause bubbles inside the resin layer and uneven streaks on the surface of the resin layer due to a step between the lid-shaped member and the surface of the disk-shaped substrate material, and the layer thickness (film thickness) becomes uneven. There was a point.

The present invention relates to a disc-shaped substrate material for an optical disc, which is made from a viewpoint different from the above-mentioned conventional technique, and further to a die device for producing the optical disc,
A mold device capable of manufacturing a disc-shaped substrate material for an optical disc with high precision and uniform thickness without causing coating failure even if a light-transmissive resin is spin-coated on the information recording surface side from the central portion. The purpose is to provide.

[0019]

As a result of earnest research, the inventors of the present invention have made a disc-shaped substrate material once without forming a central hole in the central portion thereof at the time of injection molding which is one of the optical disc manufacturing processes. After being formed and taken out, a film forming step, a resin layer forming step, etc. are performed as they are, and then a center hole is formed to form an optical disk. Also, paying attention to the shape of the stamper applied at the time of injection molding. , The central hole is not provided in the vicinity of the center or a through hole having a diameter smaller than the central hole of the obtained optical disk is formed so that the mold dividing line does not occur on the information recording surface side from the through hole to the outer periphery. In order to solve the above problems, the side surface of the light transmitting layer of the disk-shaped substrate material is formed by a stamper.

That is, the above problems can be solved by the following inventions.

(1) Manufacture of a disk-shaped substrate material for injection-molding a disk-shaped substrate material for an optical disk having a center hole in the center by using a mold and a stamper arranged in the cavity of the mold. A mold apparatus for use, wherein various functional layers are formed on a predetermined area in a range including an information area on the information recording surface side of the disc-shaped substrate material, and information recording and / or reproduction is possible. The mold has no mold dividing line on the information recording surface forming surface in the area corresponding to the optical disk except the central hole portion on the information recording surface side. A die device for manufacturing a disk-shaped substrate material, which is formed continuously in a radial direction.

(2) A sprue bush is provided in the center of the die on the side of the information recording surface, and a convex portion is provided in the center of the side opposite to the information recording surface. A sprue runner that is integral with the disc-shaped substrate material between the sprue bush and the convex portion, and a recess can be formed on the opposite side of the sprue runner for manufacturing the disc-shaped substrate material (1) Mold equipment.

(3) A center hole is formed in the disk-shaped substrate material during injection molding or in any of the subsequent steps, and the stamper has a through hole having a diameter smaller than that of the center hole at the center thereof. The die device for manufacturing a disk-shaped substrate material according to (1), characterized in that the region between the through hole and the outer peripheral portion is a continuous stamper surface.

(4) A gate, which is integrally formed with the disc-shaped substrate material at the time of injection molding, is provided at the center of the side opposite to the information recording surface (1).
Alternatively, the mold device for manufacturing a disk-shaped substrate material according to (2).

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

First, referring to FIG. 1, a disk shape for a disk-shaped optical recording medium (hereinafter referred to as an optical disk) 20 manufactured by a mold device 30 (see FIG. 2) according to a first example of an embodiment of the present invention. The process of processing the substrate material 12 will be described.
Here, the diameter of the center hole 28 (see FIG. 1E) of the optical disc 20 obtained from the disc-shaped substrate material 12 is set to 15 mm.

In the method of manufacturing the optical disk 20, first, the stamper 1 having the pattern 15 for forming the information recording surface is formed.
0 (see FIG. 1 (A)) is set in the mold device 30,
The disk-shaped substrate material 12 is molded by injecting molten synthetic resin into the cavity 31 of the mold device 30.

This pattern 15 is formed on the surface of the stamper 10 on the side of the cavity 31 and forms a region which becomes the information recording surface 12A of the disk-shaped substrate material 12. The pattern 15 is provided according to the format of the optical disc 20 obtained by providing the center hole 28.

In the injection molding process, the disk-shaped substrate material 12 with the sprue runners 14 integrally attached thereto is molded into the mold without removing the central portion of the disk-shaped substrate material 12, that is, without forming a center hole. Taking out from the apparatus 30 (see FIG. 1B), sputtering process (FIG. 1C)
(See FIG. 1D), spin coat process (see FIG. 1D) and the like, and finally the center hole 28 is removed together with the sprue runner 14 to form the optical disc 20.

As shown in FIG. 2, the mold apparatus 30 has
The stamper 10 has a fixed mold 32 and a movable mold 34, and a through hole 10A having an inner diameter of 10 mm is formed in the center of the stamper 10. The stamper 10 is arranged on the movable mold 34 side in the mold device 30. Gate 33 for injecting molten synthetic resin
And is located on the opposite side. Reference numeral 32A in FIG. 2 indicates a sprue bush, and 34A indicates a stamper holder.

As described above, the stamper 10 is arranged on the movable mold 34 side, and the movable mold 34 is provided with the suction means 36 for sucking and fixing the stamper 10 by negative pressure. Has been. This suction means 36 is
For example, it is made of continuous foam metal to which a negative pressure is applied from the back surface, and is configured to suck the stamper 10 and maintain the flat surface (mirror surface) of the stamper 10 against the pressure of the resin.

Therefore, the surface of the stamper 10 on the pattern 15 side covers the entire area outside the central hole 28 on the information recording surface 12A side of the disk-shaped substrate material 12, and within this area the mold wire is formed. Does not exist.

Further, at the position of the through hole 10A in the center of the stamper 10, a releasing means 38 composed of, for example, an ejector pin is arranged inside the stamper holder 34A, and a mold is passed through the through hole 10A. The disk-shaped substrate material 12 that protrudes into the cavity 31 of the device 30 and is solidified after injection molding is pushed to release the disk-shaped substrate material 12 from the movable mold 34 that is separated from the fixed mold 32. ing.

Here, the stamper 10 is configured such that the through hole 10A of the stamper 10 is brought into contact with the stamper holder 34A to perform positioning in the radial direction of the stamper. Further, at least a part of the surface of the fixed mold 32 on the side of the cavity 31 may be used for adjusting the releasability from the mold by forming a processing pattern that is visually recognizable.

In this mold device 30, the synthetic resin in a molten state is injected from the gate 33 into the cavity 31, and after the disk-shaped substrate material 12 is solidified in the cavity 31, the movable mold 34 is fixed. Away from the mold 32,
Thereafter, the tip of the releasing means 38 is projected from the through hole 10A in the direction of the fixed die 32, and the solidified disk-shaped substrate material 12 is released from the movable die 34.

Since the disc-shaped substrate material 12 released from the mold device 30 has the sprue runner 14 integrated as shown in FIG. 1B, the meat portion is continuous from the central portion to the outer peripheral edge. In this state, the inorganic material 16 is sputtered on the information recording surface 12A to form the thin film 17 in this state, as shown in FIG. 1C. A concave portion 12B is formed on the opposite side of the disc-shaped substrate material 12 from the sprue runner 14 by the tip of the stamper holder 34A and the releasing means 38.
The sprue runner 14 is formed on the surface opposite to the information recording surface 12A.

As shown in FIG. 1D, a resin material for forming a light-transmissive resin layer 19 is applied to the disk-shaped substrate material 12 having a thin film 17 formed by sputtering, for example, by a spin coating method. . Here, an ultraviolet curable resin is used, and after application, it is irradiated with ultraviolet rays to be cured, and thereafter, as shown in FIG. 1 (E), the sprue runner 14 is subjected to ultrasonic pressing 25 or simple punching.
The portion is punched at the step portion position shown by reference numeral 28A in FIG. 2 to form a desired center hole 28, and the optical disc 20 is completed.

Since the back side of the sprue runner 14 is the recess 12B, punching is easy and the waste of material is small. Further, this recess 12B is useful for positioning such as sputtering and spin coating and fixing to the device until punching.

As described above, in the optical disc 20, since there is no mold dividing line on the information recording surface 12A side of the disc-shaped substrate material 12, the light-transmissive resin layer 19 applied and formed by the spin coating method. There is no defective coating portion, and the light transmissive resin layer 19 can have a highly accurate thickness.

The first example of the above-mentioned embodiment is the mold apparatus 30 in which the stamper is on the movable side, but the stamper is on the fixed side as in the second example of the embodiment shown in FIG. The mold device 40 in FIG. 4 or the mold device 50 in which a through hole is not provided in the stamper as in the third example of the embodiment shown in FIG. 4 may be used.

The mold apparatus 40 of the second example of the embodiment shown in FIG. 3 has a fixed mold 42 on the upper side and a movable mold 44 on the lower side.
The stamper 10 is suction-held on the fixed mold 42 side by the suction means 46 similar to the above. Reference numeral 43B in FIG. 3 denotes a concave portion, and 48 denotes a releasing means. Note that a visually recognizable pattern (texture processing here) 44
B is formed on the movable mold 44 side.

The through hole 10A of the stamper 10 has a smaller diameter than the central hole 43A of the disk-shaped substrate material 43,
In addition, in the through hole 10A, the sprue bush 42A
3 is positioned by the lower end outer peripheral step portion 42B in FIG. This mold device 40 is not provided with a stamper holder.

Also in the case of the disk-shaped substrate material 43 manufactured by this mold device 40, the sprue runner 45 is integrally formed and has no central hole, and the central hole 28 is formed in a later step. The mold parting line does not appear on the outside of the. The sprue runner 45 is formed on the information recording surface side of the disc-shaped substrate material 43. or,
On the side of the disk-shaped substrate material 43 opposite to the stamper 10, a visible pattern (texture-processed here; not shown) is formed.

Next, the mold apparatus 50 of the third example of the embodiment shown in FIG. 4 will be described.

This mold device 50 has a fixed mold 5 on the upper side.
2, the movable mold 54 is arranged on the lower side,
The stamper 51 is suction-held on the movable mold 54 side by the suction means 56 similar to the above. The stamper 51 has no through hole.

The stamper 51 has an outer peripheral end portion 51.
At B, the positioning is performed by the positioning protrusion 54A of the movable mold 54. In FIG. 4, reference numeral 52A is a sprue bush, 52B is a visually observable pattern (texture-processed here), and 55 is a sprue runner.

In this mold apparatus 50, the disk-shaped substrate material 53 is injection-molded to solidify the molten resin, and then the disk-shaped substrate material 5 is used when separating the movable mold 54.
The mold 3 is released from the movable mold 54 while leaving the fixed mold 52. Then, the other side of the sprue runner 55 is sucked by a take-out machine having a suction means, and taken out from the mold device 50.

The disc-shaped substrate material 53 manufactured by the mold device 50 is integrally provided with a sprue runner 55 on the side opposite to the information recording surface, and the mold dividing line is formed over the entire area of the information recording surface. It doesn't appear.

Incidentally, in the mold apparatus shown in FIGS.
By adopting the hot runner method, it is possible to shorten or almost eliminate the columnar portions of the sprue runners 14, 45, 55, which is preferable.

Further, the concave portions 12B and 43B in the central portion
Is a concave portion 6 of another aspect as shown in FIGS.
0A to 60D is conceivable, which is useful for positioning and fixing the obtained disc-shaped substrate materials 61A to 61D in a later step. Furthermore, if the diameter of this concave portion is set as the diameter of the central hole of the optical disc. It is more preferable because punching can be easily performed. Reference numerals 62A to 62 in FIG.
D indicates a sprue runner. The effect of each of the four modes does not change, but there is no problem in forming the resin layer when formed on the information recording surface side like the recesses 60B and 60D shown in FIGS. 5B and 5D. It is preferable that the depth is about the same. Considering this, FIG.
It is preferable to form it on the surface opposite to the information surface, such as the concave portions 60A and 60C in (C).

[0051]

According to the present invention, since the mold device is constructed as described above, the surface of the disk-shaped optical recording medium to be formed is
Since there is no mold parting line due to mold parts or the like and there is no center hole, it is possible to reduce the variation in in-plane film thickness of the resin layer formed thereafter. Have.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a disk-shaped substrate material manufactured by a mold device according to a first example of an embodiment of the present invention and a process of manufacturing an optical disk from the disk-shaped substrate material.

FIG. 2 is a sectional view showing a mold device according to a first example of the same embodiment.

FIG. 3 is a cross-sectional view showing a mold device according to a second example of the embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a mold device according to a third example of the embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view showing an aspect of a recess formed in the central portion of a disk-shaped substrate material.

FIG. 6 is a cross-sectional view showing a mold device used for manufacturing a conventional disc-shaped substrate material.

[Explanation of symbols]

10, 51 ... Stamper 10A ... Through hole 51B ... Outer peripheral end portions 12, 43, 53, 61A, 61B, 61C, 61D ...
Disc-shaped substrate material 12A ... Information recording surfaces 12B, 43B, 60A, 60B, 60C, 60D ... Recesses 14, 45, 55, 62A, 62B, 62C, 62D ...
Sprue runner 15 ... Pattern 20 ... Optical disk 30, 40, 50 ... Mold device 31 ... Cavity 32, 42, 52 ... Fixed mold 33 ... Gate 34, 44, 54 ... Movable mold 36, 46, 56 ... Adsorption means 38 , 48 ... Mold release means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mamoru Usami             1-13-1, Nihonbashi, Chuo-ku, Tokyo             -In DC Inc. F term (reference) 4F202 AH79 CA11 CB01 CK41                 5D121 AA02 DD05 DD18

Claims (4)

[Claims] 1. A disk-shaped substrate material manufacturing method for manufacturing a disk-shaped substrate material for an optical disk having a central hole in a central portion by injection molding using a mold and a stamper arranged in a cavity of the mold. A mold device, wherein various functional layers are formed on a predetermined area in a range including an information area on the information recording surface side of the disk-shaped substrate material, and information recording and / or reproduction is possible. The mold has a mold dividing line on the information recording surface forming surface, and a diameter of the disk-shaped substrate material, in a range corresponding to the portion which becomes the optical disc on the information recording surface side except the central hole portion. A die device for manufacturing a disk-shaped substrate material, which is formed continuously in a direction. 2. The sprue bush according to claim 1, further comprising a sprue bush in a central portion of the mold on the information recording surface side,
A sprue runner integral with the disc-shaped substrate material and a sprue runner of the sprue runner provided between the sprue bush and the convex portion at the time of injection molding. A mold device for manufacturing a disk-shaped substrate material, wherein a recess can be formed on the opposite side. 3. The disk-shaped substrate material according to claim 1, wherein a center hole is formed during injection molding or in any step thereafter, and the stamper has a diameter smaller than that of the center hole at the center thereof. And a region between the through hole and the outer peripheral portion is a continuous stamper surface. 4. The disk-shaped disk according to claim 1, further comprising a gate integrally formed with the disk-shaped substrate material at the center of the side opposite to the information recording surface at the time of injection molding. Mold equipment for manufacturing substrate materials.