JPH03205628A - Production of information recording medium - Google Patents

Abstract

PURPOSE:To improve quality and productivity of the medium by providing recessed steps on at least one of the inner circumference area or outermost circumference area of two substrates the signal surface side of which face to each other. CONSTITUTION:Recessed steps 14, 13 are provided on the inner circumference area and outermost circumference area, respectively, of the signal surface side of a disk transparent substrate 1. This disk is put on a roller conveyer with the recording film 2 upside, and an adhesive 4 is applied on the recording film 2. Then two substrates 1 are superposed, pressed with press boards 11, 12 and stuck together. In this process, the inner circumference area and outermost circumference area of the substrates 1 are not coated with the adhesive 4 because the steps 14, 13, are provided there, two substrates can be stuck without squeezing of the adhesive 4 from the edges of the center hole and outer circumference. Thereby, the quality and productivity of the medium can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing information recording media such as optical discs, magnetic cards, and optical cards that optically record and reproduce information.

[Conventional technology]

As is well known, optical disks as this type of information recording medium are high-density, high-capacity information recording media, and are used for document files, image files, computer memory, etc., so they have extremely high reliability. is required.

Conventionally, such optical discs are 1) one with a single-plate structure in which a recording film is formed on a substrate made of a transparent material, and 2) two optical discs with a single-plate structure with spacers interposed between the inner and outer peripheries. The 3N type is known because of the following reasons: 3) a sandwich structure in which two single-plate optical discs are bonded together with adhesive so that the entire surface is in close contact with each other; However, the most reliable optical disk is one with a full-surface adhesive structure as shown in 3), which has better mechanical strength such as impact resistance and peeling resistance than those in 1) and 2). It also has excellent resistance to humidity and temperature changes (weather resistance), and is less likely to warp.

As a prior art method for laminating optical discs with a full-surface adhesive structure, there is a method for laminating hot-melt adhesives using a roll coater, as described in JP-A-58-8536, for example. It is known that this method has excellent mass productivity and can produce optical discs of excellent quality.

FIGS. 4(A) to 4(D) show an example of a conventional optical disk manufacturing method using the above-mentioned prior art. In FIG. 4(A), a disk-shaped transparent substrate (1) having a center hole (6)
After forming a recording film (2) thereon by a method such as vacuum evaporation or sputtering, the substrate (2) is moved on a roller conveyor (10) in the direction of the arrow using a roll coater as shown in FIG. +) onto the coating roll (8) with the presser roll (9), apply the melted hot melt adhesive (4) in the heating tank (3) onto the recording film (2).
) to a thickness of about 30 to 50 μm.

Next, the two substrates (1) coated with the hot-melt adhesive (4) are polymerized with the adhesive-coated surfaces facing inside, and then pressed as shown in FIG. 4(C). The lamination is performed by applying pressure using the upper and lower press plates (11) and (12) of the machine.

[Problem to be solved by the invention]

However, according to the above-mentioned conventional method, as shown in FIG. 4(D), adhesive is deposited on the edge of the center hole (6) and the outer peripheral end surface of the substrate (1) due to the press processing during bonding. Protruding portions (7a) (7b) are generated. For this reason, when the inner circumference and outer circumferential edge portions are held by hand during handling, or when the optical disk is installed in a recording/reproducing device, the centering shaft that clamps the optical disk comes into contact with the inner diameter portion of the optical disk, and the adhesive The protruding parts (7a) and (7b) fall off and adhere to the surface of the optical disc, causing optical problems and making recording and playback impossible. In addition, a separate process is required to remove any excess adhesive after bonding.

That is, in the process of removing the adhesive protruding parts (7a) and (7b), although the protruding part (7b) on the outer peripheral end surface of the optical disk can be easily removed by cutting, etc., the number of man-hours increases accordingly. There was a problem in that it invited

On the other hand, the protruding portion (7a) of the inner peripheral end surface of the optical disc
For this, the center hole (8) formed during substrate manufacturing requires a highly accurate hole diameter, and the width 1 provided on the recording surface
．． Since it has an eccentricity of 0 to 2.0 μm from the spiral or concentric recording/reproducing guide groove, easy machining is not allowed. For this reason, the center hole (B) must be post-processed by cutting, etc. while correcting the eccentricity with the recording/reproducing guide groove using a CCD camera, etc., which requires expensive processing machines and increased man-hours. This led to increased costs.

Furthermore, when bonding two substrates together, a shaft (5) for preventing misalignment is passed through the center hole (G) of the substrate to prevent misalignment during pressing, but the concentric hole (6)
Since the adhesive (7a) (7b) protruding from the end surface adheres to this shaft (5) for preventing misalignment, it becomes difficult to remove the optical disc from the shaft (5) for preventing misalignment after lamination. There is also the problem that complicated work is required, such as the need to replace and clean the shaft (5) for preventing positional deviation, and that productivity deteriorates.

The present invention was made to solve the above-mentioned problems, and it is possible to bond two substrates together without the adhesive protruding from the center hole of the substrates and the outer peripheral end surface.
It is an object of the present invention to provide a highly productive method for manufacturing optical discs with an excellent yield rate.

[Means to solve the problem]

In order to achieve the above object, the method for manufacturing an information recording medium according to the present invention includes forming a recording film layer on at least one of two transparent resin substrates, and forming a recording film layer on the recording film layer of the substrate. After applying a hot melt adhesive using a roll coater, the two substrates are polymerized and bonded together under pressure so that the adhesive layer is on the inside, thereby producing an optical information recording medium. The method is characterized in that, prior to the step of bonding the two substrates together, a recessed step is provided on at least one of the innermost and outermost peripheries of the two substrates facing each other on the signal side sides. It is something to do.

Further, it is desirable that the depressed level difference be formed to a depth of 0.21 cm or more.

Furthermore, as a means for providing recessed steps at the innermost and outermost portions of the signal side of the board, a portion of the mold for molding the board corresponding to the innermost and outermost portions of the signal side of the board is provided. Specifically, an eject ring for ejecting the molded substrate is provided at a position corresponding to the innermost circumference on the signal surface side of the substrate, and this eject ring is inserted into the recording/reproducing guide groove. Prepare a substrate molding die that protrudes from the surface of the transfer stamper,
When molding the substrate using this substrate molding mold,
The part of the eject ring that protrudes from the stamper surface provides a recessed step at the innermost circumference on the signal surface side of the substrate, and the outer circumferential ring that fixes the outer circumference of the stamper for recording and reproducing guide groove transfer is attached to the substrate. A substrate molding mold is prepared in which the outer ring is provided at a position corresponding to the outermost peripheral portion on the signal side side of the stamper and protrudes from the surface of the stamper, and when the substrate is molded by this substrate molding mold, A recessed step is provided at the outermost peripheral portion of the substrate on the signal surface side by a portion of the outer peripheral ring that protrudes from the stamper surface.

[Function] In general, a roll coater, as outlined in the above-mentioned conventional example, is equipped with a metal applicator roll that applies the adhesive under a heating tank that melts the hot-melt adhesive. In addition, the structure is such that a hard rubber pressing roll is provided below the coating roll to press the substrate against the coating roll.

That is, by rotating the applicator roll and presser roll, the substrate is poured with the coating surface in the gap between the two rolls, which have high rigidity and high parallelism, and the adhesive adhering to the applicator roll is recorded on the substrate. Since the adhesive is transferred onto the film at a thickness of 20 to 30 μm, if there is a locally depressed portion on the coating side of the substrate, the adhesive will not be transferred to that portion.

In this way, since no adhesive is applied to the depressed step portions provided at the innermost and outermost peripheries on the signal surface side of the board, the pressing process at the time of bonding removes the edges from the center hole end face and outer periphery end face of the board. This prevents the adhesive from extruding, making it possible to significantly improve quality, productivity, and costs.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

The following embodiments apply the present invention to a method of manufacturing an optical disc, and in the drawings explaining each embodiment, common reference numerals are given to parts that have the same structure and function as those of the conventional example. do.

11th 'Illusion 1' Figures 1(A) to (D) are diagrams for explaining step-by-step the process of laminating a double-sided recordable and reproducible optical disc having a full-surface contact structure and showing a first embodiment of the method of the present invention. be.

In FIG. 1(A), the steps (14) and (13) recessed at the innermost and outermost peripheries on the signal surface side of the disk-shaped transparent substrate (1) having a center hole (6) are formed to a depth of 0. .2mm~0.
5-Panel, with a width of 0.5 to 2 cm, and a recording film (2) is deposited on the signal surface to a thickness of 500 mm by vapor deposition, sputtering, etc.
Formed from A to 700A. Next, as shown in FIG. 1(B), the substrate (1) is placed on a rotating roller conveyor 00) with the recording film (2) as a recording film layer facing upward, and sent to a roll coater. .

As a result, the substrate (1) passes through the gap between the coating roll (8) with the hot-melt adhesive (4) and the presser roll (9) that presses the substrate (1) onto the coating roll (8). The melt adhesive (4) is placed on the recording film (2).
It is applied in a thickness of 0μ to 30μ. At this time, the steps (14) (1
3), the adhesive (4) does not adhere.

Next, as shown in FIG. 1(C), the center hole (6) of the two substrates (1) coated with the adhesive (4) has a slightly smaller outer diameter than the center hole (6). They are passed through a cylindrical misalignment prevention shaft (5), overlapped, and bonded together by applying pressure using an upper press plate (11) and a lower press plate (12) provided on the upper and lower sides.

According to this manufacturing method, as shown in FIG. 1(D), there are steps (14
) (13), the adhesive (4) is not applied, so even if pressure is applied, the adhesive (4) can be bonded without protruding from the end face of the center hole (6) and the outer peripheral end face.

In addition, the hot melt adhesive (4) is heated in the heating tank (3).
Heat to 100°C to 170°C to dissolve and reduce the viscosity to 1.
It is desirable to apply the coating in a state of 0,000 to 50,000 cPs. Further, it is preferable to set the gap between the application roll (8) and the presser roll (9) to about 80% of the thickness of the substrate (1), since this will reduce uneven coating.

Therefore, the thickness of the optical disc substrate is generally about 1.2
mm, the roll gap is approximately 1 mm. That is, it is effective if the steps (14) and (13) provided at the innermost and outermost peripheries on the substrate signal surface side are 0.2 m or more.

As the substrate (1) used in the present invention, acrylic resins, polycarbonate resins, etc., which have been commonly used in the past and have excellent light transmission properties, can be used.

Further, as the adhesive (4), a commonly used urethane-based or polyolefin-based hot melt adhesive made of thermoplastic rubber can be used as long as it does not attack the recording film (2). . Furthermore, the recording film (2) may be of any type, such as TeOx, TbFeCo, or the like, as long as it can be recorded and reproduced by light such as laser light.

In this embodiment, a case has been described in which L-shaped recessed steps are provided at the innermost and outermost peripheries on the signal surface side of the substrate (1), but as shown in FIG. A similar effect can be obtained when chamfering is performed in a curved manner as shown in Figure 3 (B), or when a step-like step is provided as shown in Figure 3 (C). It will be done.

21st Ω illusion 4 Next, a second embodiment of the present invention will be described.

FIGS. 2(A) to 2(C) show a method of manufacturing a substrate in the method of manufacturing an optical disk according to this embodiment, and are cross-sectional views of a mold for molding a substrate.

In Fig. 2 (A) and (B), (M) is the movable side mold, (
F) is the stationary mold. In addition, (15) is a cavity insert, (lfi) is a core insert (male type), (
I7) is a cavity (material filling space), this cavity (17) is formed by a core insert (1G) and a cavity insert (15), and this cavity (
A resin is injected into the cavity (I7), and a resin substrate having the same shape as the cavity (I7) is molded.

(18) is a core insert (16) in which melted resin material is injected from the center of the cavity (17) toward the outer periphery.
It is a sprue installed in the center of the. (19) is a stamper placed in the cavity insert (15) and transfers the recording/reproduction guide groove to the substrate (1), and (20) is a stamper holder that fixes the inner circumference of the stamper (19). .

(2l) is an outer circumference ring that fixes the outer circumference of the stamper (19), and is provided at a portion corresponding to the outermost circumference of the substrate (1).

(22) is an eject ring for ejecting the board (1), which is provided at a portion corresponding to the innermost circumference of the board;
As shown in Figure (B), after opening the mold, the substrate (I) is pushed out. (23) is the cavity insert} (1
This is a cutter for punching out the center hole (6) of the substrate 0) provided at the center of the substrate 5).

In the mold for molding an optical disc substrate configured as described above, the eject ring (22) and the outer ring (2
l) from the surface of the stamper (l9) into the cavity (l7).
) side so that it protrudes by 0.2 to 0.5 mm, the substrate (1
) is obtained.

In FIG. 2(C), (24) is the signal surface on which recording II (2) is applied.

Therefore, if an optical disk is manufactured by the means described in the first embodiment of the present invention using the substrate (1) shown in FIG. (
4) Since it is possible to eliminate protrusion, the quality, productivity, and cost of optical discs can be significantly improved. In the above embodiment, the case of manufacturing an optical disk has been described, but the present invention can also be applied to a magnetic or optical card having a laminated structure.

〔Effect of the invention〕

As explained above, according to the present invention, during roll coating, it is possible to apply adhesive to the innermost and outermost peripheries on the signal side of the board without adhering it to the end surface of the center hole of the board. Two substrates can be bonded together without any adhesive sticking out.

As a result, the adhesive protruding from the inner and outer peripheral edge portions does not fall off and adhere to the surface of the optical disc, making recording and reproduction impossible, and it is possible to improve the quality. In addition, there is no need to correct the center hole by post-processing such as cutting after bonding to remove the adhesive protruding from the inner peripheral end face, and the number of man-hours and cost can be reduced.

Furthermore, since it is possible to prevent the adhesive protruding from the center hole from adhering to the misalignment prevention shaft and hardening, it is easy to remove the substrate from the misalignment prevention shaft after bonding.
It has demonstrated superior effects never seen before, such as being able to improve productivity.

[Brief explanation of drawings]

1(A) to 1(D) respectively show a first embodiment of the method for manufacturing an optical disc of the present invention, and FIG. Figure 2 shows an embodiment of the substrate manufacturing method in the optical disc manufacturing method of the present invention, and Figure 2 (▲)
is a cross-sectional view of the substrate molding die, FIG. 2(B) is a cross-sectional view of the substrate molding die showing another operating state, and FIG. 2(C) is a cross-sectional view of the substrate molding die.
is a cross-sectional view of the disk obtained by the same mold, and Figure 3 (
A) to (C) are cross-sectional views of a substrate showing specific examples of the shapes of depressed steps provided at the innermost and outermost peripheries of the substrate in the method of manufacturing an optical disc of the present invention, respectively;
FIGS. 4(A) to 4(D) are diagrams illustrating a conventional method for manufacturing an optical disc, showing in order the process of laminating a double-sided recordable and reproducible optical disc having a fully adhesive structure. (1)...Substrate, (2)...Recording film layer, (4)...
・Hot melt adhesive, (7a) (7b)...Adhesive protrusion, (l3)...Outermost periphery step, (14)
...Innermost step. (19)...Stambar, (2
1)...Outer ring, (22)...Eject ring, (20...Signal surface. Figure 2 (A) Figure 3 (A) Figure 3 (B) Figure 3 (C)

Claims (4)

[Claims] (1) After forming a recording film layer on the signal surface of at least one of the two transparent resin substrates and applying a hot melt adhesive onto the recording film layer of the substrate using a roll coater, A method for manufacturing an optical information recording medium by polymerizing and pressurizing the two substrates so that the adhesive layer is on the inside, and prior to the step of bonding the two substrates together. A method for manufacturing an information recording medium, comprising: providing a recessed step in at least one of the innermost and outermost peripheral portions of two substrates facing each other on the signal surface side. (2) The method for manufacturing an information recording medium according to claim 1, wherein the depressed step is formed to a depth of 0.2 mm or more. (3) An eject ring for ejecting the molded substrate is provided at a position corresponding to the innermost circumference on the signal surface side of the substrate, and this eject ring is made to protrude from the surface of the recording/reproducing guide groove transfer stamper. A substrate molding mold is prepared, and when the substrate is molded by the substrate molding mold, a portion of the eject ring protruding from the stamper surface is depressed into the innermost peripheral portion of the signal surface side of the substrate. 2. The method for manufacturing an information recording medium according to claim 1, wherein a step is provided. (4) Forming a substrate by providing an outer ring for fixing the outer circumference of the stamper for recording and reproducing guide grooves at a position corresponding to the outermost circumference on the signal side of the substrate, and protruding from the surface of the stamper. A mold for molding the substrate is prepared, and when the substrate is molded by the mold for molding the substrate, a recessed step is provided at the outermost peripheral portion of the signal surface side of the substrate by a portion of the outer peripheral ring that protrudes from the stamper surface. A method for manufacturing an information recording medium according to item (1).