JPH01300442A - Production of optical disk substrate - Google Patents

Abstract

PURPOSE:To prevent the thickness of substrates from locally increasing in the outermost circumferential part at the time of sticking the substrates with an adhesive agent by providing a step thinly in the thickness direction to the entire outermost circumferential part of the surface (opposite to the film forming surface) of a resin molded base material. CONSTITUTION:A movable side specular surface 1 mounted with a stamper 3 and an outer circumferential ring 4 which determines the outside diameter size of the resin molded base material 9a are inserted to a movable side outside cylinder 5 and are mounted to the movable side of a molding machine. On the other hand, an outer circumferential ring 13 of the mirror surface is built to a stationary side mirror surface 2a and is inserted to a stationary side outside cylinder 6 which is mounted to the stationary side of the molding machine. A molten resin is packed into the cavity 7a between the outside cylinder 6 and the outside cylinder 5 and is solidified, by which the resin molded base material 9a is obtd. and the step is formed to the outer circumferential part of the surface on the side opposite to the signal surface formed by the stamper 3. The molding burrs formed between the ring 4 and the ring 13 are, therefore, prevented from being formed thicker than the surface formed of the specular surface 2a as shown in the part B of the figure. The bleeding of the adhesive agent in the sticking stage is stopped by the step part in this way and the thickness of the substrate is prevented from increasing in the outermost circumferential part.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is mainly used as an optical information recording medium2/,
The present invention relates to a method of manufacturing an optical disk substrate such as an optical disk or a magneto-optical disk (hereinafter referred to as an optical disk).

2. Description of the Related Art In recent years, optical disk drives have come to be used as storage devices for computers and the like, similar to magnetic disk drives. The optical disc substrate used in this optical disc device is made of transparent plastic such as acrylic resin or polycarbonate resin, or glass, and has a disc-shaped common phase surface coated with selenium (Se) or tellurium (hereinafter referred to as a reflective film). These are representative examples. An optical disk device rotates this optical disk substrate and records and reproduces information by irradiating the optical disk with a laser beam according to a signal.

If the base material is plastic, the typical manufacturing method for such optical disc substrates involves the process of molding the resin molding base material using an injection molding machine, compression molding machine, casting mold, etc., and the process of molding the resin molding base material. A film forming step of forming a reflective film layer on a base material by 3-1 times, and a resin molded base material with a reflective film layer on a resin molded base material with a retroreflective film layer or without a reflective film. It is manufactured using a bonding process in which it is bonded to a resin molded base material, and in order to improve the appearance quality, a process of applying adhesive to the edge of the optical disc substrate or hard coating the surface may be added. .

Hereinafter, a method of manufacturing an optical disk substrate that has been put into practical use will be described with reference to the drawings.

5 to 8 are diagrams showing a conventional method of manufacturing an optical disc substrate. FIG. 5 is a partial sectional view of a mold when obtaining a resin molded base material by injection molding, in which 1 is a mirror surface on the movable side;
2 is a fixed side mirror surface, 3 is a stamper, 4 is an outer ring, 5 movable side outer cylinders, 6 is a fixed side outer cylinder, 7 is a cavity, and 8 is a sprue runner.

In FIG. 6, 9 is a resin molded base material, and in FIG. 7,
1o is a reflective film layer, in FIG. 8, 11 is the same resin molded base material on the protective side as 9, and 12 is an adhesive layer.

When the resin molding base material 9 is molded using the injection mold shown in FIG. Tube 5
At the same time, the fixed side outer cylinder 6 with the fixed side mirror surface 2 is clamped under high pressure to form a cavity 7 in which a resin molded base material 9 is formed.

This cavity Y is filled with molten resin at high pressure and high speed from the Nupul runner 8 to obtain a resin molded base material 9.

When molding is carried out based on the above-mentioned manufacturing method, molding cracks always occur on the resin molding base material 9 from the mating surfaces of the mold parts, as shown in FIG. 6A.

Next, as shown in FIG. 7, a metal film of tellurium or selenium is formed as a reflective film layer 10 on the signal surface (stamper 30) of the resin molded member 9 by vapor deposition or sputtering.

As shown in FIG. 8, the resin molded base material 9 on which the reflective film layer 10 is formed is bonded to the protective plate 5 and the side resin molded base material 11 via an adhesive layer 12 to protect the reflective film.
Optical disk substrates are manufactured.

However, in the above-mentioned manufacturing process, the adhesive present in the bonding process protrudes from the outer peripheral end face, travels along the end face to the surface of the resin molded base materials 9 and 11, and the thickness of the optical disk substrate is reduced as shown in FIG. However, it has the disadvantage that it becomes locally thick at the outermost periphery.

In particular, as seen in the conventional example, there was a problem in that the thickness of the resin molded base material became even larger when it was shot.

Problems to be Solved by the Invention One of the problems in the optical disk substrate manufacturing process described above is that the adhesive present in the bonding process protrudes from the outer peripheral end surface.
There was a drawback that the optical disc substrate was thickened at the outermost portion because the optical disc substrate ran along the end face to the surface of the resin molded base material. However, even when an adhesive is additionally applied to finish the outer peripheral end surface, there is a similar drawback that the outermost peripheral part of the optical disc substrate becomes thicker.

In particular, when a resin molding base material is molded by injection molding or the like, there is a problem in that molding burrs occur in the outermost circumference of the coat, and the thickness is further increased due to the burrs.

The disadvantage that the outermost periphery of these optical disk substrates is thick is that when the optical disk substrate is stored in a cartridge and used,
It is conceivable to increase the size of the storage area for the disc plate when touching the cartridge, but this is easy due to the relationship between the optical disc device (drive) and the 4-type optical disc board. Unfortunately, you can consider reducing the amount of adhesive so that it doesn't protrude, but this will weaken the bonding strength. Therefore, at present, it is extremely difficult to minimize the outer periphery of the resin molded base material obtained by molding, and to minimize the amount of adhesive protruding in the bonding process without weakening the bonding strength. Adjustments are being made.

In view of this, the present invention has been designed to prevent the adhesive present in the process of bonding optical disk substrates from protruding from the outer peripheral end surface and reaching the surface of the resin-molded base material during bonding, whereby the thickness of the optical disk substrate is locally reduced at the outermost portion. The purpose of this is to solve the problem of increased thickness without reducing the strength of the lamination.

Means to Solve the Problem In the present invention, a thin step is provided in the thickness direction around the entire outermost periphery of the resin molded base material (opposite to the film forming surface), and adhesive generated during the bonding process is removed. The protrusion of the adhesive or the bleeding of the adhesive for finishing the outer circumferential end surface is received by the step part, so that the increase in thickness caused by the protrusion of the adhesive is absorbed by the step part. It is.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIGS. 1 to 4 are diagrams for explaining the method of manufacturing an optical disc substrate according to the present invention.

be. FIG. 1 is a sectional view of the main part of a mold when a resin molded base material is obtained by injection molding, and a mirror outer circumferential ring 13 is newly provided on the outer periphery of the fixed side mirror surface 2a.

2 shows a resin molded base material 9a molded with the mold shown in FIG. 1, FIG. 3 shows a resin molded base material 9a with a reflective film layer 10 formed thereon, and FIG. 4 shows a resin molded base material 9a formed with a reflective film layer 10. A protective resin molded base material 11a molded using the same mold is bonded to a resin molded base material 9a with a reflective film layer 10 shown in FIG. 3 using an adhesive layer 12. Note that 14 in FIG. 2 is a center hole that is automatically punched out when molding is performed using the mold shown in FIG. 5, and its explanation is omitted since it has little relevance to the present invention.

A method of manufacturing the optical disc substrate of this embodiment configured as described above will be explained.

The case where the resin molding base material 9a is molded using the injection mold shown in FIG. 1 will be described. The movable side mirror surface 1 to which the stamper 3 for forming the signal surface and signal pits as an optical disc substrate is attached and the outer circumferential ring 4 that determines the outer diameter of the resin molding base material 9a are inserted into the movable side outer cylinder 5, and the molding machine starts. It is attached to the movable side (movement 1) 11). On the other hand, the fixed side mirror surface 2a
A mirror-surface outer peripheral ring 13 as intended by the present invention is incorporated into the molding machine, inserted into the stationary side outer cylinder 6, and attached to the stationary side of the molding machine.

High-pressure mold clamping is performed between the fixed outer cylinder 6 and the movable outer cylinder 5, forming a cavity 7a that forms a resin molded base material 9a. In this cavity 7a, polycarbonate, Akira IJ
A resin-molded base material 9a is obtained by filling and solidifying a molten resin with excellent optical properties, such as molten resin, through a Nupuru runner 8 at high pressure and high speed.

The resin molded base material 9a molded based on this manufacturing method is
As shown in part B of the figure, a step is formed on the outer periphery of the surface opposite to the signal surface formed by the stamper 3. Therefore, the molded surface formed between the outer circumferential ring 4 and the mirror-surfaced outer circumferential ring 13 does not become thicker than the surface formed by the fixed-side mirror surface 2a, as shown in part B. Furthermore, since the outer peripheral portion becomes thinner, there is also a ripple effect in that the molding edges are reduced compared to the conventional one.

10.\-7 Next, in the film forming process, the resin molded base material 98 is formed using conventional technology K.
The seventh layer is made of a metal film of selenium (Se), tellurium (Te), palladium (Pd), etc. as the reflective film layer 1o.
The νth part of the ward is formed on the surface of the stamper 3 side.

The resin molded base material 9a with the reflective film 1-10 created through the film forming process is coated with the same protective plate side resin as the resin molded base material 9a shown in FIG. 2 in the lamination process shown in FIG. Molding base material 11
Place a and the signal side (stamper 3 side) facing each other and apply 1 x 1 adhesive.
2, and is cured and bonded using bonito or ultraviolet rays. In the thus obtained optical disc substrate, as shown in FIG. 4, the adhesive layer 12 protrudes from the outer periphery of the resin-molded substrate 9a and spreads to the surface (anti-film-forming surface) of the resin-molded substrate 9a. Even if the thickness (tl) of the optical disk substrate at the outer peripheral part becomes thicker, the thickness (t2) of the optical disc substrate becomes thicker.
) cannot be thicker than that.

In the normal mass production process, the adhesive of the adhesive layer 12 protrudes in this way and increases the thickness of the optical disk substrate by 0.1 + 0.5 mm, and the molding paris shown in section B in Figure 2 is increased. Including this, it becomes 0.2-0.6. Therefore, it is sufficient to obtain the intended effect of the present invention if the step in the thickness direction provided at the outermost periphery of the surface (anti-film forming surface) of the resin molded substrate 9a is 0.6 mm.

However, considering that there was no such step in the past, 0.
Even a small step of one armpit or less can achieve this effect. On the other hand, if the step is made too thick, the thickness of the normal resin molded hole material (
1,15111111 to 1.3 mm), abnormalities occur in the strength of the outermost periphery, warping during molding, etc. Therefore, it is desirable that the number of steps provided at the outermost circumference is 0.6 or less.

Further, it is necessary to form a thin step on the outermost periphery of the surface (anti-film forming surface) of the resin molded substrate 9a outside the information recording boundary on the outer periphery.

The information recording boundary refers to the boundary of the outer periphery where the consumer actually records and plays back. Providing a step inside this information recording boundary may change the thickness of the resin molding hole material and interfere with optical properties. Because there is.

As described above, according to this embodiment, by providing a step in the thickness direction on the entire outermost periphery of the anti-film-forming surface of the molded resin base material, that is, the surface opposite to the signal surface, the optical disc substrate is This eliminates the problem of the thickness becoming thicker at the outermost periphery, making it possible to obtain a constant thickness of the optical disc substrate.

In this example, a single-sided optical disk substrate was described in which two resin-molded substrates were bonded together and a reflective film layer was formed on only one of the resin-molded substrates. Exactly the same effect can be obtained with a double-sided optical disk substrate with a layer formed thereon, and it is not limited to single-sided use as shown in the examples.In addition, the material, size, molding method, etc. of the optical disk substrate, etc. It is not subject to or limited to.

In addition, if an additional step such as applying adhesive is provided to improve the finish of the outer peripheral end surface after the bonding step,
The bleeding of the adhesive is stopped by the step in the thickness direction all around the outermost periphery, and more effective results can be obtained.

Effects of the Invention As described above, the present invention provides at least the resin molding base 13...
.

A film forming process that forms a reflective layer on the material, and a resin molded base material that has a reflective film layer and a resin molded base material that has a reflective film layer or a resin molded base material that does not have a reflective film layer with an adhesive. In a method of manufacturing optical disk substrates using a bonding process, the resin molded base material is provided with a thin step in the thickness direction around the entire outermost periphery of the surface (anti-film forming surface), and the adhesive generated in the bonding process is This stepped portion is designed to stop the protrusion of the adhesive or the bleeding of the adhesive for finishing the outer peripheral end surface.

This eliminates the problem that the thickness of the optical disc substrate becomes thicker at the outermost periphery, and allows the optical disc substrate to have a constant thickness.

Therefore, when an optical disk substrate is stored in a cartridge and used, conventionally, the outermost edge of the optical disk substrate is finished using an adhesive so that the outermost edge of the optical disk substrate does not touch the inner wall of the cartridge case. 14/\-7 Extremely difficult manufacturing work was required, such as fine-tuning the laminating process to avoid an increase in thickness, or managing resin molding JI = Ig to reduce molding gaps. However, according to the present invention, this problem has been solved, manufacturing has become easier, and when the cartridge is housed, the thickness of the cartridge can be reduced and the size can be reduced.

Furthermore, when molding a resin molded base material based on the present invention,
Since the thickness of the outermost peripheral portion is thin, cooling is quick and molding flashes are less likely to occur, thereby reducing the influence of molding flashes on the thickness of the outermost peripheral portion of the optical disk substrate.

This also has the ripple effect of reducing the problem of cracked and molded particles detaching and adhering to the resin molding base material, resulting in defective optical disk substrates.

In addition, by forming a step on the outer periphery of the resin molded substrate surface outside the information recording boundary on the outer periphery,
There are no problems with prevention of abnormalities in the optical properties of the optical disc substrate, strength of the outermost periphery, recoil during molding, birefringence, etc.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of an optical disc according to an embodiment of the present invention, FIG. 2 is a sectional view of its resin molded base material, FIG. 3 is a sectional view of its resin molded base material with a reflective film layer, and FIG. 4 5 is a partial sectional view of a molding die for molding a resin molded base material in a conventional optical disc substrate manufacturing method, FIG. 6 is a sectional view of the resin molded base material, and FIG. 7 is a sectional view of the optical disc substrate. The figure is a sectional view of the resin molded base material with a reflective film layer, and FIG. 8 is a sectional view of the optical disc substrate. 1...Movable side mirror surface, 2,2a...Fixed side mirror surface,
3...Nutampa, 4...Outer ring, 9.9a
... Resin molding base material, 10 ... Reflective film layer, 1
2... Adhesive layer, 13... Mirror surface outer ring. Name of agent: Patent attorney Toshio Nakao and one other person

Claims (2)

[Claims] (1) A film forming step of forming at least a resin molded substrate and a reflective film layer, and a resin molded base material having the reflective film layer and a resin molded base material having a reflective film layer or a resin molding without a reflective film layer. It has a bonding process of bonding the base material with an adhesive, and the resin molded base material has excess adhesive generated in the bonding process on the entire outermost periphery of its surface (anti-film forming surface). Alternatively, a method for manufacturing an optical disk substrate, characterized in that a step is provided thinly in the thickness direction to receive an adhesive for finishing the outer peripheral end surface. (2) The method of manufacturing an optical disk substrate according to claim 1, wherein the thin step is provided at the outermost peripheral portion of the surface outside the information recording boundary on the outer peripheral surface.