JPS58173626A - Reproductive preparation of information disk - Google Patents

Abstract

PURPOSE:To obtain a copy of an information disk which is uniform in thickness of its molded resin layer and free from air bubbles and warp by such an arrangement wherein a base board is arranged opposingly to a metal mold with a specified space provided between them, and after radial ray setting resin is injected into said space, the injecting hole of said resin is closed and then radial rays are illuminated. CONSTITUTION:A radial ray permeable base board 4 is arranged opposingly to a metal mold 1 with a fixed interval 13 provided between them. A movable part 9 is caused to descend and a resin passage 12 is opened and radial ray setting resin 16 is injected into said space 13 through the passage 12. After that, the passage 12 is shut off from the space 13 by causing the movable part 9 to ascend and radial rays are illuminated from a source of radial rays 17 through the base board 4 and the molding resin layer 16 is integrated with the base board 4 by hardening it. After that, a reproduced disk is obtained by peeling the mold resin layer 16 off from the metal mold 1. By this method, a reproduced copy of an information disk which is uniform in thickness of its molded resin layer and free from air bubbles and warp can be obtained.

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a method for manufacturing copies of information discs such as video discs and digital audio discs. [Technical characteristics of the invention and its problems] Conventionally, known methods for producing copies of information discs include the combination carbon molding method, the injection molding method, and the cast molding method. In the Punpressi molding method, the mold has a structure that can be heated and cooled, a thermoplastic resin that is above its melting point is inserted into the mold, and the mold is heated to high temperatures. This is a method of molding under high pressure and then molding with a cooling cycle to harden the resin body to obtain a duplicate disk. A duplicate disk is obtained by injecting resin at high pressure. Although these methods have excellent productivity, the information signals from the irregularities on the mold cannot be accurately transferred to the Australian-made disk, and the structure is constructed under high temperature and pressure, so the equipment and equipment are large. It has scale and beak value, which is its lack of dependence. On the other hand, although the cast molding method has the advantage of high transfer accuracy, cast molding using a normal thermosetting resin requires a long curing time of several hours or more, and productivity is extremely low. Note carefully
The resin is cured by exposing it to radiation such as ultraviolet rays and electron beams. When using radiation-cured resin, the time required for layering is shortened by compression molding, injection molding, and injection molding.
It has attracted attention in recent years because it has been found that the equipment and equipment are relatively inexpensive, and that the transfer accuracy of duplicate disks is excellent. A method for producing copies of information discs using radiation-curable resin is as described in Japanese Patent Publication No. 53-33244, in which a mold is flattened (covered) with liquid molding resin, a disc is pressed against it, and a presser plate is used to spread the molded resin layer to a predetermined thickness. A method of obtaining a duplicate disk by pressurizing the resin until it becomes thick and then curing the resin by irradiation with radiation and peeling the cured molded resin layer from the mold, as well as the method of obtaining a duplicate disk from the mold, and the method of JP-A-53-116105, on which the resin is cured by radiation irradiation. Drop a radiation-cured resin onto the mold, press the base that has been deformed into a convex spherical shape, and stretch the resin flat on the mold, or deform the resin into a convex spherical shape and press the resin with the base. There is also a method in which the resin is stretched around the entire circumference between the mold and the base, and then cured and peeled off by radiation irradiation to obtain a duplicate disk.Alternatively, the base is pressurized with a roller to uniformly spread the resin layer on the mold. However, with any of these methods, when the liquid molding resin is dropped, it pushes against the gold@IK substrate, and bubbles are generated that stretch the resin, but the air bubbles mixed into the resin are Discs using the non-contact external playback method cause information signal loss and dropouts, which seriously degrades image and sound quality.Furthermore, with contact playback discs, air bubbles on the disc surface may drop out as well. Regardless of the playback method, the resin layer is not suitable for any playback method, as this can cause discs to play out and also create steps that can cause damage to the playback stylus.

[It is clear that it is absolutely necessary to prevent the formation of bubbles. On the other hand, the mold and the base of JP-A-55-152028 were arranged facing each other, and after injecting radiation-cured resin into the space between them, the thickness of the molded resin layer was reduced to a predetermined thickness by pressing. There is also a known method in which the disk is cured by radiation irradiation and then peeled off to obtain a duplicate disk, but in this method, after injecting the radiation-cured resin, the resin layer is generally stretched by pressing.
It is difficult to control the resin layer thickness. In other words, the above-mentioned cast molding method using radiation-cured resin can only transfer information signals to one side of the substrate in one molding process, but since the radiation-cured resin shrinks when it hardens, this is usually not possible. Replicated discs made by this method exhibit a tendency for the molded resin layer to warp in certain corners. However, the warpage of the disc has a negative effect on the tracking of the playback device during playback, so in practice, the composition of the molding resin and the thickness of the scissor resin layer are set so that the warpage is within a certain limit. Although efforts have been made to obtain disks that do not cause problems, the composition of the molding resin is often determined by other factors, such as transferability of unevenness (information signals) and adhesion to the substrate. In order to reduce the amount of resin, it is necessary to control the thickness of the molded resin layer, and in order to obtain a high-definition disc, it is necessary to determine the resin thickness with an accuracy of several dozen tones. In JP-A-55-152028, in order to accurately define the thickness of the resin layer, a protrusion with a step equal to the thickness of the mold and the base plate is provided, and the molded resin is applied with pressure during molding. It is stated that the interface between the protrusion and the base is removed, the two are brought into close contact, and a predetermined film thickness is formed by the step of this protrusion. The resin that enters the area forms a liquid film, which is ±0 as described here.
．． Even if it is practical enough to allow a variation in film thickness of about 1 inch, it is insufficient in terms of precision to manufacture a disc with reduced warpage. In the examples in which the thickness was formed, a similar decrease in accuracy occurred due to the formation of a liquid film. From the above-mentioned viewpoint, the present inventors arranged the base in advance with respect to the mold at a predetermined distance, and the J! By injecting radiation-cured resin into the space while maintaining the distance between the discs and curing the resin by irradiating with radiation, there is no air bubbles in the wrinkled resin layer, and the resin layer thickness is uniform and warped. We have already devised a method for obtaining copies of information discs without oxidation, but in this method, the inlet of the tooth passageway through which the radiation-cured resin is injected into the space between the base and the mold is exposed to the irradiation of curing radiation and is exposed to the isthmus. In order to prevent the molding resin from hardening and making it impossible to use the passage W4 from now on, a shield plate or a shield part was provided to shield the part # from the radiation. From this, the resin in the resin passage remained uncured even after curing by radiation irradiation, making continuous use possible, but on the other hand, there was a problem that uncured molding resin remained on the base and mold. occured. On the foundation! ! Even if the remaining uncured resin is removed by wiping, solvent washing, dissolving, etc., it will harden and be removed by irradiation again, but the uncured resin remaining on the mold will damage the mold and cause damage to the molding resin. This type of treatment is not possible due to the contamination of different components, and when molding continuously, it becomes a trap to place the base where uncured resin remains on the mold. At this time, a large number of air bubbles are mixed into the molded resin between the mold and the substrate, and uncured resin adheres to the film thickness defining surface for forming a predetermined film thickness, resulting in a decrease in film thickness due to the formation of a liquid film. There was a gap. [Object of the Invention] The present invention has been made to solve the above-mentioned drawbacks, and it is possible to create a W-shaped disc using a cast molding method using a radiation-cured resin.
With the I-manufacturing method, there is no uncured resin remaining on the mold, no air bubbles are mixed into the molded resin layer, and the thickness of the molded resin layer is uniform, resulting in high-precision discs with less dropouts and warpage. The present invention relates to a method for producing copies of information discs that can be obtained. [Invention 1! In the present invention, a base plate is placed facing a mold at a predetermined distance, and a radiation-cured resin is injected into the space between the molds while maintaining the distance between the bases, and then the injection port for the resin is opened. By closing the resin passage, the resin in the resin passage is properly removed, and radiation is irradiated, thereby obtaining a reproduction of an information disk with no air bubbles leaking in, a uniform resin layer thickness, and no warpage. [Invention 1! EXAMPLE The present invention will now be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of the method for producing a copy of an information disc according to the present invention. In FIG. 1, a mold 1 having an information signal due to unevenness is fixed to a mold body 2 at the center with a center pin 3. On the other hand, the radiolucent substrate 4 is held in a detachable manner by a substrate holder 5, and in this example, the substrate 4 is held when the suction #I6 is depressurized. The central bin 3 has a central part 8 having a positioning center holder 7 at the center, a movable part 9, and an outer peripheral part 10.
The movable part 9 has a structure that can move up and down between the center part 8 and the outer peripheral part 10, and the base 4 has a protrusion 7K in the center.
It has a positioning hole l] that fits together. Figure @1 shows the normal state, where the movable part 9 is at the upper limit position, the upper end surface of the isthmus is on the same plane as the mold 1 surface, and the p1 molding resin passage '12 is blocked by the gap 13 between the gold ml and the base 4. ing. Also, the mold 1 is adjusted so that the film thickness defining surface 14 of the center portion 8 is the same size as the thickness of the desired radiation-cured resin, that is, the molded resin layer, using the center pin 3.
The substrate 4 protrudes from the surface, so that if the substrate 4 is brought into close contact with the film thickness defining surface 7, a desired spacing 13 can be easily formed in the molded resin layer. Subsequently, as shown in FIG. 2, the movable part 9 is lowered to the lower limit position where the resin passage 12 is opened, and the radiation-cured resin is passed from the passage 12 through the opening 15 created by the lowering of the movable part 9 into the space 13. inject. After forming the resin layer 16 on the entire information signal surface of the mold 1, the movable part 9
is raised and returned to the upper limit position, the passage 2 and the interval 13 are placed in the proper position, and the holder ^5 is returned to normal pressure, the holder ^5 is attached and detached from the base 4, and the radiation source 17 is placed in its place. . The resin layer 16 is hardened and integrated with the substrate 4 by irradiating an appropriate amount of radiation from the radiation source 17 through the substrate 4, but since the entire surface of the resin layer 16 is exposed to radiation, there is no After this, the hardening part can occur.
The resin layer 16 is peeled off from the mold 1 to obtain a duplicate disk. Radiation used for curing includes ultraviolet electron beams, gamma rays, etc., but from the viewpoint of ease of handling, safety, and productivity, a near-ultraviolet mercury lamp is used as the light source. A method of curing with ultraviolet rays in several seconds to several tens of seconds is preferred. When ultraviolet rays are used as the curing radiation for the base material, glass, plastic, such as backboard lath, Pyrex, quartz glass, acrylic resin, polycarbonate resin, 8mmN@resin, etc. can be used, and the weight and mechanical Acrylic resin is often used due to its physical properties and price. [Effects of the Invention] According to the present invention, the distance 13 between the mold 1 and the base 4 is accurately defined by the film thickness regulation [114] of the center pin 3,
In addition, the film thickness defining surface 14 is in close contact with the substrate 4 before the molding resin is injected into the interval 13, and there is no adhesion of the molding resin to the film thickness defining surface 1fi14 and no residual resin curing residue after repeated molding. The film thickness defining surface 14 is kept clean, making it possible to mass-produce duplicate disks in which the thickness of the molded resin layer 16 is precisely defined, and to prevent uncured molded resin from being deposited onto the mold 1. There is no residue, air bubbles are prevented from entering the molded resin layer 16 during repeated molding, and a high-quality duplicate disk without dropouts can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is a cross-sectional view when the molded resin is injected, and FIG. 3 is a cross-sectional view when the resin is cured. 1...Mold, 2...Model body, 3...Center pin, 4
... Base, 5... Base holder, 6... Suction groove, 7
...Positioning protrusion, 8.Center, 9.Movable part, IO.Outer circumferential part, 11.Positioning hole, 12.
... Resin passageway, 13... Spacing, 14... Thickness regulating surface, 15... Opening part, 16... Forming resin layer, 17...
radiation source.

Claims (1)

[Claims] In a method for manufacturing information discs using a cast molding method using radiation-cured resin, a radiation-transparent substrate is irradiated with radiation over the entire surface at regular intervals, facing a mold having an information signal consisting of unevenness. a step of injecting a radiation-cured resin into the skeletal space, a step of closing the connection between the cough space and the radiation-cured resin passage, and a step of curing the resin by irradiating the radiation. A method for producing a copy of an information disc, characterized in that: