JPS5940340A - Production of information recording carrier - Google Patents

Abstract

PURPOSE:To produce an information recording carrier with high reliability and a low production cost, by joining together two disk resin base materials by a thickness control member, and hardening a swelled adhesive after subjecting to preprocessing to prevent generation of lines on a disk. CONSTITUTION:An additional layer 6 of photosetting resin is provided to a resin base material 5, and a photorecording layer 7 is vapor deposited to the surface of the layer 6. A similar additional layer 6' is provided to a resin base material 5' which is equal to the material 5. Both layers 6 and 6' and joined together through entire surface with a photosetting adhesive 9 by putting a spacer 8 between pressure plates 3 and 3'. For junction of resin substrates 10 and 10', the adhesive is applied the middle circumference part of one of the substrates 10 and 10'. Then the other substrate is put on the substrate coated with the adhesive 9, and the adhesive 9 is expanded almost over the entire surface. Then both substrates are held between the plates 3 and 3', and pressure is applied to these substrates. The plate 3' is removed, and the ultraviolet rays are irradiated from the side of the substrate 10' to harden the adhesive 9. The adhesive 11 swelled out to the outer circumference of the substrate by pressure can be prevented from going into the area between the outer surfaces of substrates 5 and 5' and plates 3 and 3' by forming grooves 12 and 12' at a place which is slightly smaller than the outer diameter of a disk.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a disc-shaped information recording carrier used in optical recording or reproducing systems, and is intended to reduce and eliminate high-frequency components of surface runout. It is something.

Conventional configuration and its problems In the optical recording and reproducing system, the optical recording layer of a rotationally driven disk-shaped information recording carrier (hereinafter referred to as a disk) is irradiated with a laser beam corresponding to an information signal. Information can be recorded by providing optical shading or unevenness on the optical recording layer.
This method performs reproduction and can record minute signals of several micrometers, and in principle enables high-density recording on the order of the wavelength of light. However, since the laser light pickup and the disk do not come into contact during recording and playback, there is no wear and tear, and it provides multiple functions such as still images and high-speed search, and is suitable for industrial use, such as still image files and document files.

It is also being put into practical use for commercial purposes.

For discs used in this way, for example, if the wave-like surface runout that occurs in the circumferential direction of the disc has locally high frequency components (hereinafter referred to as wrinkles), the pink amplifier will control the focus on the recording surface. There are things I can't do. In this case, the signal may be recorded poorly, causing disturbances on the screen during playback, or in the case of a color image, the colors may appear dark and light, making normal recording and playback impossible. The higher the frequency of this frequency component, the more likely it is to become a problem even if the amount of surface runout is small, and wrinkles are a factor that greatly affects the yield in disk manufacturing.

Furthermore, when a disc is stored, not only under normal usage conditions, but also when it is placed in a high temperature and high humidity environment, deformation may occur over time and wrinkles may increase.

At this time, even if there were no problems during manufacturing, recording and playback may be affected over time, and in some cases there is a risk of losing important information. Sufficient physical strength is required.

Generally, when joining two discs using resin base materials, adhesive is applied to the surfaces of the discs to be joined, and then the two are overlapped and pressure is applied from the outer surfaces to press them and harden them. At this time, when pressure is simply applied from the outer surface without regulating the thickness of the joint, the thickness of the joint often becomes uneven and mechanically unbalanced force is applied. These often cause wrinkles on the disc.

In addition, as shown in Figure 1, if the adhesive 2 protruding from the outermost periphery of the disk 1 is cured while remaining in an irregular state, internal stress will be generated in an unbalanced state during curing, especially at the outer periphery of the disk. There are many things that can cause wrinkles.

Furthermore, if the adhesive 2 that has protruded out is allowed to harden in a state where it has penetrated between the outer surface of the disk 1 and the pressure members 3, 3' as shown in Figure 1C, the overall thickness of the disk will be uneven. or locally generates internal stress, which remains as residual stress even after the adhesive 4 that has protruded or penetrated is treated.
It causes wrinkles.

OBJECTS OF THE INVENTION The present invention provides a method for manufacturing an information recording carrier that eliminates the above-mentioned drawbacks and prevents the occurrence of wrinkles.

Structure of the Invention The present invention prevents wrinkles on the disc by joining two disc resin base materials using a thickness regulating member for the joining part, pre-treating the adhesive that protrudes from the outer periphery of the disc, and then curing the adhesive. The present invention provides a method for manufacturing an information recording carrier that prevents the occurrence of , has high commercial quality and reliability, is low cost, and has excellent shape stability.

Description of examples A first embodiment of the present invention will be described with reference to the drawings.

In FIG. 2, an additional layer 6 of photocurable resin is provided on a first disk resin base material 5 made of synthetic resin, and an optical recording layer 7 that can be recorded and reproduced by laser light is further deposited on the surface of the additional layer 6 of photocurable resin. ing. In addition, the first disk resin base material 5
A second disc resin base material 5' made of the same material as,
An additional layer 6' of a similar photocurable resin is provided, and both are bonded over the entire surface with a photocurable adhesive 9 with a spacer 8 sandwiched between the pressure plates 3.3'.

At this time, the two disk resin substrates 10, 10' including the optical recording layer or the additional layer are bonded by applying the photocurable adhesive 9 to the middle circumference of one substrate in advance, and then applying the air bubbles to the other substrate. First, the photocurable adhesive 9 is spread over almost the entire surface by overlapping them so that they do not enter. Furthermore, after applying a predetermined pressure from both sides between the pressure plates 3 and 3' for a certain period of time, the pressure is released, the pressure plate 3' is removed, and the ultraviolet rays are applied from the side of the second disk resin substrate 10'. The photocurable adhesive 9 is cured by irradiating the photocurable adhesive 9 with light.

As shown in FIG. 3, the light-curing adhesive 11 that continuously protrudes in the same direction from the outermost circumference of the disk when pressurized is controlled by the amount and diameter of the first applied photo-curing adhesive 9. By doing this, the amount of protrusion can be adjusted. If the amount of overflow is small overall, the surface tension of the overflowing photocurable adhesive 11 tends to cause it to adhere unevenly to the outer circumference of the disk, but if the amount of overflow is greater than a certain amount, it will stick out in the same direction. Is possible. According to experiments, the joint thickness of a disc with an outer diameter of φ200 is 0.1f.
In the case of fla, if the coating amount of the photocurable adhesive was 911 and the coating diameter was 132, it was possible to make it continuously protrude in the same direction. At this time, the protruding photocurable adhesive 11 can be removed by forming grooves 12, 12' in the pressure plates 3, 3' from positions slightly smaller than the outer diameter of the disc, as shown in Figure 3. Seepage between the outer surfaces of the substrates 5, 5' and the pressure plates 3, 31 can be prevented. This is because the photo-curable adhesive 11 is prevented from coming into direct contact with the pressure plates 3, 3', and even if it comes down due to the pSN force, it will hardly seep in.

In this way, it is possible to prevent the occurrence of internal stress and thickness unevenness due to local protrusion or seepage as in the past, and the overall thickness of the entire disk is regulated by the spacer 8, resulting in good thickness accuracy. The dynamic balance with respect to the rotation of the disc when mounted on the deck is also sufficiently stable.

Two disc resin substrates 10, including of course additional layers,
If the thickness of 10' falls within the allowable range, the thickness unevenness of the adhesive layer itself can be minimized, and wrinkles due to the thickness unevenness will not occur on the outer surface of the disk.

Additionally, when the adhesive is curing, it is necessary to release the pressure; however, if UV irradiation is applied while the pressure is applied, the thermal expansion of only one side of the disk due to the irradiation heat will occur simultaneously with the curing of the adhesive. As the disk progresses, stress tends to remain and often appears as surface runout when the disk returns to room temperature after curing is complete. In this case, the surface runout is not limited to a flat warpage in the radial direction, but also a wavelike warp in the circumferential direction, which is a cause of promoting wrinkles in the disk due to uneven stitching and the like. When UV irradiation is performed after the pressure is released, the disk is always free from external forces even during thermal expansion, so there is almost no residual stress, which is very advantageous in preventing wrinkles. .

Furthermore, even if the adhesive that protrudes from the outermost periphery of the disk after the light-curing adhesive has hardened is processed by machining and finished with rounding, etc., once such protruding areas have been treated, it will be necessary to create a new one. Wrinkles rarely occur.

Furthermore, since the first and second disk resin substrates 5 and 5' are made of the same material, they have the same water absorption coefficient and thermal expansion coefficient, but the first disk resin substrate 10 having the optical recording layer 7 and the second disk resin substrate 10 having the optical recording layer 7 The disc resin substrate 10' has different moisture absorption characteristics depending on the presence or absence of the optical recording layer 7. That is, the disk surface having the optical recording layer 7 does not absorb or dehumidify moisture at all, and the disk surface not having the optical recording layer 7 constantly absorbs or dehumidifies moisture depending on the external humidity state. Therefore, the first
The disk resin substrate 10 tends to generate a humidity gradient in the thickness direction between both surfaces of the disk, and the difference in expansion coefficient due to moisture within the substrate inevitably causes the disk to become sticky. Further, in the case of the second disk resin substrate 10', since it does not have the optical recording layer 7, the warpage does not appear as pronounced as in the first disk resin substrate 10, but it has a layer provided on one side for symmetry of mechanical strength. Since the disc has an additional layer 6' made of a photocurable resin, the moisture absorption characteristics between both sides of the disc are not the same. The warpage variation of these disk resin substrates 10 and 10' is φ19QM
In terms of the warp at the position, it is extremely large, at a maximum of 500 to 600 μm when the optical recording layer 7 is included, and is likely to cause an increase in wavy warpage and creases.

Therefore, these disk resin substrates 10° and 10' are stored for a long time under constant temperature and humidity conditions to equalize the moisture absorption state of each disk resin substrate 10.
, 10' are treated so that they are in an equilibrium state with respect to the same humidity.

By doing so, it is possible to equalize the amount of moisture absorption and dehumidification on both sides of the disk after bonding and assembly in response to changes in the external environment, and to minimize changes in shape over time related to surface runout and wrinkles.

Next, a second embodiment of the present invention will be described with reference to the drawings. In this embodiment, as shown in FIG.
This embodiment is the same as the first embodiment except for the disk resin substrate 10' in that the disks are stacked one on top of the other and pressurized from both sides with the spacer 8 sandwiched between the pressure plates 3 and 3'. As for the combination of disk resin substrates, there is no problem in the case of this embodiment as long as pretreatment is performed to prevent moisture absorption. Here, the photocurable adhesive 11 protruded from the outermost periphery of the disk when pressurized.
is continuously sucked by a suction jig 13 such as a vacuum pipe,
The photocurable adhesive 11 is not left attached to the outermost periphery of the disk. By doing this, it is possible to prevent seepage between the pressure plates 3, 31 and the outer surface of the disk, so there is no possibility of uneven thickness at the time of bonding, and furthermore, it is possible to prevent unevenness in the thickness when bonding. Since there is no protrusion or adhesion to the pressure jig, the occurrence of wrinkles due to residual stress can be minimized. Once an assembled disk has undergone such treatment, even if the outermost end face is machined,
As a result, new wrinkles hardly occur.

In the first and second embodiments, it is necessary to release the pressure during general ultraviolet irradiation, but the irradiation heat is very small, and the influence of the difference in thermal expansion between the two surfaces of the disk can be almost ignored. In the case of ultraviolet irradiation such as this, this is not necessarily necessary. Further, as a matter of course, removal of the pressure plate at the time of irradiation is not necessary in the case of a pressure plate that transmits ultraviolet rays.

As the adhesive in the above embodiments, not only a photocurable adhesive but also a thermosetting epoxy resin, for example, can be used. In particular, when both disc resin base materials have an optical recording layer, it is not possible to bond the entire surface using a photocurable adhesive, so it is necessary to use a thermosetting or room temperature curing adhesive. .

The material for the optical recording layer must be one whose optical absorption coefficient or both optical absorption coefficient and refractive index change when irradiated with laser light; an example of this is T, a low tellurium oxide.
Some are provided with a thin film containing e0x (xki 1.0) as a main component. These thin films include G e T e
715 of S b S A s 2 S s etc.
81 22°Amorphous thin film is used. When such an optical recording layer is provided and the two disk resin base materials are to be fully laminated, it is necessary to use an adhesive that does not deteriorate the optical recording layer. For example, in the case of a photocurable adhesive,・In such cases, polyvinyl alcohol adhesive is preferable.

The above method for producing an information recording carrier is particularly effective when the material is made of an organic polymer, examples of which include acrylic resin (polymethyl methacrylate), polycarbonate, and vinyl chloride. , polystyrene, polyester.

There are acetate, etc.

Further, in the embodiments of the present invention, the presence or absence of the additional layer is not particularly necessary, and the symmetry of the mechanical strength is maintained and the water absorption of the two disk resin base materials and the substrate.

If the coefficients of thermal expansion are the same, similar effects can be obtained by adjusting the moisture absorption state.

Effects of the Invention As described above, the present invention has a simple configuration, and can provide high quality and reliability with less wrinkles on the disk not only under normal use environments but also under special environments of high temperature and high humidity. It is possible to obtain an information recording carrier with high dimensional stability, low cost, and excellent shape stability, and at the same time, it has a great effect in improving the yield during manufacturing.

[Brief explanation of drawings]

Figures 1a, b, and c show a conventional information record carrier with adhesive locally protruding or soaking in immediately after bonding and assembly, and its manufacturing process. FIG. 3a is a cross-sectional front view of the manufacturing process of the method for manufacturing an information recording carrier in the first embodiment of the invention. b is a plan view of an information recording carrier manufactured by the same method and a sectional front view of the manufacturing process thereof, and FIG. be. 3.3'...pressure member, 5.5'...disc resin base material, 6,6'...additional layer of photocurable resin, 7... ...Optical recording layer, 8,8'...
・Spacer, 9... Light curing adhesive, 10.10
'... Disc resin substrate, 11... Light curing adhesive, 12, 12'... Groove, 13.
...Suction jig. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Figure (cL) (C) Figure 2 Figure 3 (α)

Claims (1)

[Scope of Claims] (1) An information recording carrier made by bonding two disc resin base materials each having an information recording surface on at least one side with the information recording surface facing inside. 1. A method for producing an information recording carrier, characterized in that when producing the disc, pressure is applied to the joining portion using a thickness regulating member, so that the two disc resin base materials are joined over the entire surface. (2) A thickness regulating member for the joint portion is disposed outside the outermost periphery of the two disc resin base materials to join the two disc resin base materials, according to claim 1. A method for producing an information recording carrier according to claim M1, characterized in that (3) the two disk resin base materials are treated in advance to bring them into the same moisture absorption state before joining. Method. (4) The two disc resin base materials are bonded by continuously extruding an adhesive in the same direction onto the outermost periphery of the two disc resin base materials, as claimed in claim 1. A method of manufacturing an information recording carrier as described in the above. (5) Claims characterized in that: (5) the two disc resin base materials are bonded by sucking an adhesive that protrudes from the outermost periphery of the two disc resin base materials. Method 0 (6) of the information recording carrier according to claim 1, characterized in that a photocurable adhesive is used to bond the two disc resin substrates together. Production method.