JPS58121151A - Optical disk - Google Patents

Abstract

PURPOSE:To obtain an optical disk having high sensitivity and no warp, by applying the photosetting resin on one side of a transperent disk substrate made of 4-methyl pentene resin to form a recording layer made of an information bit layer and at the same time providing a metallic coating layer at the exposure side. CONSTITUTION:The poly 4-methyl pentene resin 12 is put between metallic molds 10 and 10' containing mirror surfaces 11 and 11' respectively, and the resiue is press molded when resine temperature 12 attains 240 deg.C and the molds 10 and 10' are cooled to obtain a transparent resin layer 4. The acrylic photosetting resin is applied on the layer 4, and a pattern carved information bits is set and is irradiated to obtain an optical recording layer 5 containing information bits. A metallic reflecting layer 7 of Al, etc. and a protecting layer 6 are provided at the exposure side of the layer 5 to obtain an optical disk. The resin 12 or its crosslinked polymer proves the humidity resistance, no warp and a high transparency to improve both the sensitivity and accuracy of an optical disk.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical disc formed by the 2p method (photo-polymer method), and relates to an optical disc formed by using a 4-methylpentene polymer or a crosslinked product thereof as a disc base material. , transparency, non-optical rotation (non-birefringence),
This invention relates to an optical disc with excellent moisture resistance, impact resistance, moldability, etc.

A type of information recording in which a recording layer (hereinafter referred to as information bit) that can be changed by light energy is formed on one side of the disk, a metal coating layer is formed on the exposed side, and information is reproduced by irradiating a laser beam from the disk side. -Video discs, audio discs, etc. have been developed as playback discs, and these have been rapidly developing recently. Hardened vinyl resins, polycarbonate resins, polymethyl methacrylate resins, and the like have been studied as this type of disk filler, and among these, polymethyl methacrylate resins are being increasingly used in some areas. However, these known optical disc materials have the following drawbacks, which are a major bottleneck in increasing their versatility.

In other words, with hard seeded vinyl resin, additives (plasticizers, etc. for improving moldability) bleed onto the disk surface, resulting in a decrease in light transmittance over time and a decrease in the degree of recycled M. There is a problem. On the other hand, if the amount of additive j1 is reduced, optical distortion will occur during disk molding, causing problems such as spotlighting, making it unsuitable for optical disk materials whose mission is high sensitivity and high precision. It is.

In addition, although polycarbonate thread resin has excellent transparency, heat resistance, mechanical properties, etc., it has difficulties in moldability due to its hardness, and optical distortion is likely to occur during molding (the letter D VH: /fIL is large). Therefore, errors (noise) are likely to occur during reproduction (reading) in optical discs manufactured using this resin.

On the other hand, polymethacrylic acid methi-thread polymer has transparency,
Although it has excellent non-optical rotation properties, it has poor moisture resistance and absorbs moisture in the air, causing the surface side to become rough and warped. In order to deal with this problem, reinforcing sheet metal of the same thickness as the disk plate is laminated to prevent warping, but this is far from satisfactory. Moreover, this resin has poor mechanical strength, especially impact resistance, and is easily broken, and is hard and has problems with moldability. There are attempts to improve this by adding other substances, but this results in poor heat resistance.
It becomes an obstacle in terms of dormitory use.

The inventors of the present invention have focused on the above circumstances, and believe that in order to increase the versatility of optical discs, it is necessary to find the optimal resin that meets the required characteristics, and have conducted research along this line. I've made progress. We have conducted extensive research with the hope of developing an optical disc that can satisfy all of the required characteristics shown below.

■It must not cause optical distortion to the laser beam (non-optically active) and must have sufficient transparency to allow the laser beam to pass through.

■It is essential for optical discs to maintain their appearance so that reading errors do not occur (no warpage occurs), and the main cause of warpage is thought to be hygroscopicity. The information bits formed on one side of an optical disc are made of metal that reflects laser beams. & Since a laminated layer is formed, it is necessary to provide the transparent resin with moisture absorption resistance comparable to that of metal.

■A certain level of mechanical strength is required when considering the manufacturing workability and handling during convenience of optical discs, and audio discs for automobiles also need heat resistance that can withstand temperatures of about 100'C. be.

The present invention was completed as a result of such research, and is particularly aimed at providing an optical disc using the 2p method. That is, the disk of the present invention is an optically transparent plate made of a cross-linked product of 4-methylpentene polymer or glass, and if necessary, a pufstik that has approximately the same degree of refraction as the plate. A flat coating layer with no optical defects is formed on the surface, and when the coating layer is formed, on the exposed side], the IJ changes with light energy.
A functional layer is formed, and a metal coating is completely formed on the exposed surface of the recording layer, and information is reproduced by irradiating a laser beam from the opposite side of the metal coating layer. There is value in making it possible.

The 4-methylpentene polymer used in the present invention is l
Su-4-methylbenzone-1, Bo! A copolymer of J-4-fi methylbendene-2,4-methylpentene-1 and other olefins (ethylene, propylene, isoprene, butadiene, etc.), or a copolymer kneaded with these. isoprene, polyvinyl acetate, etc.), etc.
All of these have all of the properties (υ~■) required for resins for optical discs. However, if the content of the olefin or blending polymer in the copolymer or blend is too large, In particular, the transparency and non-optical rotation of the optical disc will be reduced and the features of the present invention will be diminished.
It should be kept at most 50% by weight or less. In addition, these 4-methylpentene polymers have excellent properties as they are, but they also have the same properties as the 44-organic peroxide.
By blending with T- and cross-linking, and irradiating with radiation to cross-link, it is possible to dramatically improve the image quality. Note that the timing of the crosslinking reaction is not particularly limited.

Next, a method for manufacturing an optical disc according to the present invention will be briefly described. As shown in Figure 1 (schematic process diagram) and Figure 2 (explanatory diagram of molded bodies in each jurisdiction), after forming a conductive film on the photoresist surface 1' of the glass substrate 1 by vapor deposition or electroless plating, nickel Conduct electric plowing, master board 1m, mother board 1b, then female mold (stambar) 2 for mass duplication.
Next, using the stanbar as a mother mold, a transparent substrate 4 made of a 4-methylpentene polymer is placed through a spacer 8, and a photocurable resin 5 is placed between the stanbar 2 and the transparent substrate 4. is injected and irradiated with light from the substrate 4III to form a recording layer pit F. As mentioned above, the substrate 4 is molded from a 4-methylpentene polymer or a crosslinked product thereof, and the molding method is not particularly limited, but commonly used are injection molding, extrusion compression molding, and injection molding. Molding method, injection pressure
Ho, Oji Temple is used. That is, the above material Q200-40
It is heated to about 0° C. to melt it, and then filled into a metal mold according to the above-mentioned molding method, and then cooled down and molded. The cooling rate is 100
It is desirable that the cooling rate be at least .degree. C./sec. If the cooling rate is slow, the spheres i will grow and the transparency will decrease, so it is recommended to cool the tube as quickly as possible and all at once to around room temperature. The physical properties of the obtained substrate are not particularly limited, but based on a 1.2 ff size substrate, the 500 to 950 mμ flat light transmission system should be 85- or more, and the retardation value should be 110E.
IIt1 or less, moisture absorption rate is 0.0 at 40°C, 195%RH. It is preferable that the impact strength is 2.0/373 or higher. Further, the substrate 4 may be directly provided to the above-mentioned molding process, but a resin coat 3' having a refractive index similar to that of the substrate is formed on the opposite Im (i.e., the appearance as an optical disc product) of the bit forming surface. It is also possible to improve the smoothness of the product surface and to protect it. 11 Examples of the material for forming the fat coat 3' include acrylic resin, mehumic resin, polyurethane thread resin, and silicone thread resin, with acrylic resin being preferred. It is also preferable that the photocurable resin 5 has a refractive index similar to that of the substrate.After the injection of the photocurable resin is completed, ultraviolet rays, electron beams, radiation, etc. are emitted from the surface of the resin coat 3'. It is irradiated and cured, and an information pin (1) is formed on the interface with the stand bar 2.

Next, the metal stand bar 2 is removed, the intermediate product consisting of the resin coating, the substrate 4, and the photocuring resin layer 6 is turned over, and a metal coating layer is formed on the information bit forming surface. The metal coating layer 7 is used to reflect the laser beam irradiated from the end side of the transparent disk substrate 4 on the surface of the information bit, and the type of metal is not particularly limited, but the most common ones are aluminum, chromium, The material may be gold, silver, copper, tin, etc., and the coating layer 7 can be formed by any conventionally known method, such as vapor deposition, sputtering, ion blasting, or the like. There are no particular restrictions on the thickness as long as the primary reflection ability is effectively exhibited, but the most common thickness is 500 to 1600 Å in order to satisfy both the physical properties and economical aspects of the coating layer.
, particularly preferably about 700 to 800 people.

The optical disc of the present invention achieves its purpose with the above-mentioned configuration, but in order to prevent the metal coating layer 7 from peeling or tearing, the above-mentioned protective layer 6 (epoxy V resin, methacrylate/ L/resin, urethane resin, inorganic resin such as silicone, etc.] is preferably formed.

In the above example, one disk substrate 4 was used so that recorded information could be reproduced from only one side, but as shown in FIG. If they are combined through the media, the front and back surfaces can be used as recording and reproducing surfaces.

The present invention is roughly constructed as described above, and its effects can be summarized as follows.

That is, the 4-methylpentene polymer has extremely good transparency and non-optical rotation, and does not impede the directionality of the laser beam, which is a recording and reproducing source.

In addition, its moisture absorption resistance is as low as metal, so there is no risk of warping during storage, and it can be stored at 11F.
Since it also has f#S characteristics, it can maintain storage of recorded information and high-precision reproduction ability over a long period of time.

Next, examples of the present invention will be shown, but the following examples are of a nature that does not necessarily apply to the present invention.

In addition, in the following examples, the maximum retardation value and moisture resistance are the values measured by the following method.

[Maximum Letter Day V Yon [(R value)]

m light m hikage'tm, t Senarmon compensator (
The measurement was carried out using the Nippon Geikagakusha 111) as a sodium hump light source.

[IM resistance]

The warped optical disk was left in an atmosphere of 95% RH and 40° C., and was taken out every hour to measure the warpage (X)t as shown in FIG.

Example 1 FIG. 5 shows Example 1 of the present invention, in which 4 is a transparent resin layer, 5 is an optical recording layer having information bits, and 7 is a layer that effectively reflects laser beams incident from the transparent resin layer side. The reflective layer 6 is a protective layer that protects the reflective layer from scratches and dust. Figure 6 shows how the transparent resin 114 is molded! ill? 10' is a mirror layer 11, 1f is a metal mold, and 12 is a resin. That is, poly-4-methylpentene resin [Mitsui Petrochemical Co., Ltd. [TPX PT-18]
40 parts were placed between molds 10 and 10' having four disc-shaped parts with an inner diameter of 120 m and a total depth of 1.15 m1, and the mold was further pressurized at 10° and left for about 80 seconds. After the pressure was reduced, the mold was immediately placed in water at 20° C. and rapidly cooled. /!
A transparent resin layer 4 made of a molded poly-4-methylpentene resin was taken out.

On the obtained transparent resin layer 4, methyl methacrylate (
80 parts), methyl acrylate (10 parts), ethylene glycol dimethacrylate (20 parts), trimethylo-μ
Propane trimethacrylate (40 parts) and hibenzoin ethyl 2-5'A/(0,1 part) were coated to a thickness of 10 μm using the at-Gufbia coating method, and then a stambar with information bits engraved on it was coated. A 5 μm spacer was placed on the transparent resin 1114 and crosslinked by irradiating it with an ultraviolet hood for 10 minutes. When the stamper and spacer were removed, a 10 μm optical recording layer 5 was obtained. Approximately 1000 aluminum thin tubes were formed on the recording layer side by vacuum evaporation (reflection layer 7), followed by methyl methacrylate L'- (40 parts), methyl acrylate (5 parts), and ethylene glycol dimethacrylate (15 parts). ,
A resin consisting of trimethylolprotrimethacrylate (40 parts) and benzoin ethyl ether (0.1 parts) was spread on a cloth with a thickness of about 15 μm, and then irradiated with an ultraviolet hood for about 10 minutes to cause crosslinking and form the protective layer 6. and obtained an optical disc.

Table 1 shows the properties of the transparent resin layer, and Table 2 shows the properties of the optical disc, along with Comparative Examples 1 and 2, respectively. Transparent resin layer (has water absorbency compared to Comparative Example 1,
It can be seen that it is superior to Comparative Example 2 in terms of impact resistance and optical design (maximum retardation value).

Also, from Table 2, the transparent w fat layer l in Example 1 is:
Compared to Comparative Example 1, in terms of moisture resistance and impact resistance, Comparative Example 2
It can be seen that it is superior in terms of optical design (maximum retardation value).

Comparative Example 1 Transparent 1 (l [i layer n-, produced by heat press in the same manner as in Example 1 using commercially available polymethyl methacrylate resin)
(Resin temperature = 280″C, gauge pressure during heat press 5oKq/c11).

An optical recording layer 5, a reflective layer 7, and a protective layer 6 were laminated on the transparent resin layer 4 made of polymethyl methacrylate resin in the same manner as in Example 1 to prepare an optical disc.

Comparative Example 2 A transparent resin layer 4 was created using a commercially available polycarbonate resin using a heat press in the same manner as in Example 1 (resin temperature =
290°C, gauge pressure 70KQ/3+ during heat press
3. An optical recording layer 5, a reflective layer 7, and a protective layer 6 were laminated on the transparent resin layer 4 made of polycarbonate resin in the same manner as in Example 1 to prepare an optical disc.

Table 1 shows the properties of the transparent resin, and Table 2 shows the custom-made optical disc 1-.

Example 2 FIG. 7 shows Example 2t of the present invention, in which 3' represents a flatness improving layer and 6 represents a surface protective layer.

Transparent resin layer 4 was created as follows. In the same manner as in Example 1, a poly-4-
Methylpentene resin molding was used. This molded body under a t-Si atmosphere at room temperature with a dose rate of 5 Mra using Co60 as a radiation source.
A crosslinkable transparent resin layer 4 was obtained by irradiating with d/hr l-ray for a total of 2 hours.

N-methylated melamine 100 is added to both sides of this transparent resin layer 40.
fifS, p-) A melamine resin prepared by mixing 0.6 parts of sodium luenesulfonate was added to
After coating to a thickness of 120 #In, it was heated at 160° C. for 40 minutes to harden, thereby obtaining a surface protective layer 6 and a flatness improving layer 3', respectively. An optical recording layer 6, a reflective layer 7, and a protective layer 6 were sequentially laminated on the flatness improving layer 3' side of the obtained composite in the same manner as in Example 1 to prepare an optical disc. The characteristics of the transparent resin layer 4 are shown in Table 1, and the characteristics of the optical disc are shown in Table 2.
Each is shown in the table.

Example 8 A transparent resin layer, an optical recording layer, A reflective layer and a protective layer were formed to obtain an optical disc. Table 1 shows the properties of the transparent resin layer, and Table 2 shows the properties of the optical disc.

Example 4 Poly-4-methylpentene III)! A mixture consisting of 40 parts of trimethylolpropane trimethacrylate, 1 part of trimethylolpropane trimethacrylate, and 0.2 parts of dichloromethane was compression molded in the same manner as in Example 1 using the mold shown in FIG. A resin layer was obtained. An optical recording layer, a reflective layer, and a protective layer were sequentially formed on the transparent resin layer in the same manner as in Example 1 to obtain an optical disc. Table 1 shows the characteristics of the transparent resin layer, and Table 2 shows the characteristic sounds of the optical disc.

Example 5 FIG. 8 shows Example 5 of the present invention, and 8 is Example 1.
The reflective layer *'t of the two laminated composites of the reflective layer 7 produced in step 1 was pressed together through a polybutadiene layer having a thickness of 20 μm and heated at 100° C. to produce an optical disc.

[Brief explanation of drawings]

Figure 1 is a schematic diagram illustrating the method of manufacturing an optical disc;
Figure 2 is an explanatory diagram of the molded body in each step of Figure 1;
The figure is a 1##J schematic diagram illustrating an optical disc according to the present invention, FIG. 4 is an explanatory diagram showing a method for measuring moisture absorption resistance, and Section 6.7.
Figure 8 is a schematic cross-sectional view showing the optical disc obtained in Example 6.
The figure is a conceptual diagram of Kinkan used in the present invention. 1m...Master board 2...Stan 1<-r...
・Resin coat (flatness improving layer) 4...Transparent resin layer 5...Information bit (optical recording layer 6...Protective layer 7...Metal coating layer (reflection layer) ==] zThlb Part 3!!!

Claims (1)

[Scope of Claims] (1) A recording layer that is changeable by EIK light energy is formed on an optically transparent layer made of a 4-methylpentene polymer or a crosslinked product thereof; An optical disc characterized by forming a metal coating layer on the exposed side of the layer. (2. In claim 1, the metal coating layer-formed plates described in the same claim are bonded together with an adhesive so that the metal coating layer forming sides face each other, so that recording and reproduction are possible on both sides. (In the first claim or superposition of claim 3J, the optically transparent plate is a 4-methylpentene M polymer mixed with an organic peroxide and crosslinked. Optical disc. (4) An optical disc according to claim 1 or 2, in which the optically transparent plate is made by crosslinking a 4-methylpentene polymer by irradiation with radiation. An optical disc according to Range 1, 2 or 8, which has a back protective layer formed on the exposed side of the metal coating layer.