JPH03272034A - Optical disk and production thereof - Google Patents

Abstract

PURPOSE:To eliminate a change in the mechanical characteristics of the optical disk under a high temp. and to prevent the failure in recording and reproducing by the peeling of ceramics by forming resin substrates in such a manner that a groove is made on the outer peripheral side when the resin substrates are stuck to each other. CONSTITUTION:The substrates 1, 7 consisting of polycarbonate are formed with grooves for tracking and pit parts including information, such as address marks, on the surfaces on one side thereof by injection and compression molding and are molded to such a shape that the groove is formed in the outer peripheral part of the disk when the substrates are stuck to each other. The resin substrates 1, 7 which are successively formed with 1st ceramics layers 2, 8, recording layers 3, 9, 2nd ceramics layers 4, 10 and reflecting layers 5, 11 in this order on the side thereof are stuck to each other by using an epoxy resin and after this epoxy resin is cured, a UV curing resin 16 is packed into the groove formed in the outer peripheral part so as to fill this groove. After the UV curing resin 16 is allowed to cure, the outer peripheral part is worked by machining. The change in the mechanical characteristics of the optical disk at a high temp. and the failure in recording and reproducing by the peeling of the ceramics are prevented in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc for recording, reproducing, or erasing information using light, and a method for manufacturing the same.

[Prior Art] Conventional optical disks have been bonded together by a roll coating method in which adhesive is applied using a roll using a hot-melt bonding agent and bonded together.

Bonding using adhesive sheets or epoxy adhesives is also being considered. The adhesive sheet was pasted together using a vacuum press. In the case of bonding using epoxy adhesive, the structure was such that the outer periphery was processed after bonding with epoxy adhesive.

[Problem to be solved by the invention] However, the conventional technology had the following problems.

Because hot-melt adhesives are thermoplastic resins, they are not heat resistant and their mechanical properties change at high temperatures, which imposes many restrictions on the use and storage of optical discs.

There are problems with long-term reliability. When bonding using an adhesive sheet, the same applies to hot melt adhesives.

It lacks heat resistance and has problems with long-term reliability. Epoxy adhesives are heat resistant and their mechanical properties do not change even at high temperatures, but
Because of the strong adhesive force, the resin substrate and the first ceramic layer tend to peel off, and when an impact is applied to the disk, that part peels off, causing problems such as making recording and reproduction impossible.

Therefore, the present invention is intended to solve such problems, and its objectives are as follows. Unlike bonding using hot-melt adhesives or adhesive sheets, the mechanical properties do not change at high temperatures, so there are fewer restrictions on the use and storage of optical discs, and they are reliable over the long term.

Unlike when bonding in a conventional structure using epoxy adhesive, the adhesive strength is strong, so there is no separation between the resin substrate and the first ceramic layer, and when an impact is applied to the disk. That part peels off.

The objective is to provide an optical disc that does not have problems such as recording and reproduction being impossible.

[Means for Solving the Problems] The optical disc of the present invention is characterized in that the resin substrate used for the first disc is molded so that a groove is formed on the outer circumferential side when the resin substrates are bonded together.

In addition, in the method for manufacturing an optical disk of the present invention, the above-mentioned resin substrate is formed with tracking grooves or bits, and a first ceramic layer and a recording layer are formed on the side of the above-mentioned resin substrate on which the above-mentioned grooves or bits are formed. , after the second ceramic layer 2 and the reflective layer were sequentially formed and bonded together using an epoxy resin, and the epoxy resin was cured.

After filling the groove created on the outer periphery with ultraviolet curing resin and curing the ultraviolet curing resin.

It is characterized by cutting the outer periphery.

[Function] Since the adhesive layer of the disc is made of epoxy, the mechanical properties of the optical disc do not change even at high temperatures. Also.

Since the outer periphery is covered with ultraviolet curing resin, there is a strong adhesion to the resin substrate, so there is no possibility that the ceramic will peel off from the substrate if it falls, making it impossible to record and reproduce.

[Example] The present invention will be explained in detail below based on the drawings.

FIG. 1 is a basic configuration diagram of an optical disc according to the present invention,
FIG. 2 is a schematic diagram of a method for manufacturing an optical disc according to the present invention.

1 and 7 are polycarbonate substrates, 2 and 8 are 5iA
IN layer, 3 and 9 are TbFeCo layers, 4 and 10 are 5i
AIN layer, 5 and 11 are Al-Ta-5i layers, 6 is an adhesive layer, 12 and 13 are hard coat layers, 14 and 15 are antistatic layers, and 16 is an ultraviolet curing resin part.

The polycarbonate substrates 1 and 7 are injection compression molded to form a bit part containing information such as tracking grooves and address marks on two sides, and are shaped so that a groove will be formed when they are attached to the outer periphery of the disk. Molded. After forming hard coat layers 12 and 13, antistatic coat layers 14 and 15 were formed. Therefore, those with hard coat defects or antistatic coating defects were removed and the process proceeded to the next step. The S 1AIN layers Nos. 2 and 8 were formed by RF reaction magnetron sputtering using a mixed gas of nitrogen and argon using a sintered target of 5IA1. 3 and 9 Nd
The DyFeCo layer was formed by DC magnetron sputtering using an alloy target of N(IDyFeCo).

Similar to the 5iAIN layers 2 and 8, the 5iAIN layers of 4 and 1O were formed by the RF reaction magnetron sputtering method by introducing a mixed gas of nitrogen and argon. 5 and 11 Al-Ta-3i layers are Al-T
The film was formed by DC magnetron sputtering using an a-3i target and introducing argon gas.

The adhesive layer of No. 6 is Epicron S- from Dainippon Ink and Chemicals.
129 and oil-based shell epoxy epi-gyunia - IBMI -
12 and 1,6-hexanediol diacrylate and [-
A mixture of butyl peroxyisobutyrate and Ciba Geigy's Irgacure 907 is coated in a ring shape on the side on which the recording layer is formed, and then combined with another substrate in a vacuum system to form a bonded substrate. Place it on a hot plate or put it in an oven to spread the adhesive, and irradiate it with ultraviolet light using a metal halide lamp or high-pressure mercury lamp.
The adhesive in the area where the recording layer was not formed was temporarily cured, and then left for 72 hours to cure the adhesive layer. Thereafter, the adhesive layer was cured by heating at 50°C for 3 hours, 60°C for 8 hours, and 80°C for 2 hours.

Further, since it is better to make the thickness of the adhesive layer 60μ or less from the viewpoint of weather resistance, the thickness of the adhesive layer needs to be 60μ or less. Preferably 50μ or less.

More preferably, the amount of adhesive is adjusted so that it is 4゛0μ or less, and the temperature is adjusted when spreading the adhesive.

Alternatively, it is better to press or the like when bonding.

For the hard coat layers 12 and 13, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, and Ciba Geigy's Irgacure 907 were spin-coded onto the substrate surface, and then cured by irradiating ultraviolet rays with a high-pressure mercury lamp. It is something.

By pasting them together as described above, a groove as shown in FIG. 2(a) is formed in the outer peripheral portion of the optical disc. As shown in FIG. 2(b), the grooves were filled with ultraviolet curable resin, and the ultraviolet curable resin was cured as shown in FIG. 2(C).

The outer periphery was processed and finished as shown in FIG. 2(d).

In Fig. 2(a) to Fig. 2(d), 17 is a groove formed on the outer periphery, 18 is an ultraviolet curing resin portion filled to fill 17, 19 is a high-pressure mercury lamp, and 20 is a portion cut on the outer periphery. It is.

Here, the shape of the groove formed on the outer periphery of the disk does not have to be a semicircular hollow shape as shown in FIG. . Further, it is preferable that the size of this groove be less than half the thickness of the bonded disks. That is, when the thickness of the bonded disks is 2.4 mm, the width of the groove is 1.4 mm.
2mm or less is preferable. The depth of the groove is preferably 0.2 mm or more.

The ultraviolet curing resin part of 16 is urethane acrylate) 40 parts, )! 30 parts of J propylene glycol, 1 part of trimethylolpropane triacrylate.

A mixture of 2 parts of γ-methacryloxypropyltrimethoxysilane and 4 parts of Ciba Geigy's Irgacure 907 as an ultraviolet curing agent was applied to the outer periphery of the disk while rotating the disk, and irradiated with ultraviolet rays. and cured. Next, we performed a cutting process to scrape off the ultraviolet curing resin that overflowed from the outer periphery of the disk.

The antistatic layers Nos. 14 and 15 were formed using Guicure EX-801 manufactured by Dainippon Ink and Chemicals by a spin-coding method.

In addition, as the adhesive layer of No. 6, Ciba Geigy's Irgacure 907 was added to a bisphenol F-based epoxy resin in which 20% of the total epoxy groups are acryloyl groups.
5%, oily shell epoxy Ebicure BMI-12
When an optical disc was prepared using 6% of γ-glycidoxypropyltrimethoxysilane and 3% of γ-glycidoxypropyltrimethoxysilane, with the other conditions unchanged from the configuration shown in Figure 1, the results were almost the same as in Figure 1. An optical disc with these characteristics was created.

According to the optical disc of the present invention, since the discs were bonded together using an epoxy adhesive, the mechanical properties of the optical disc did not change even when left at high temperature (90° C. for 50 hours). However, when optical disks were bonded together using a hot-melt adhesive, which is a conventional method, the value of surface runout acceleration doubled when left at high temperatures.

Furthermore, since the optical disk of the present invention has an ultraviolet curing resin layer formed on the outer circumferential side, no peeling occurred even in a drop test (76 cm); Peeling occurred on the side.

It should be noted that the present invention should not be considered limited to these embodiments, and various modifications can be made without departing from the gist of the present invention.

In the present invention, the adhesive includes at least an epoxy main ingredient and a curing agent, a mixture of an ultraviolet curable resin main ingredient and a curing agent, and an organic peroxide added thereto, or a compound 1 having an epoxy group and a (meth)acryloyl group. For example, a photopolymerization initiator, an epoxy curing agent, and an organic oxide as necessary are added to a partially (meth)acryloyl-modified epoxy compound such as bisphenol A, bisphenol F type, phenol novolac type, or cresol novolac type. It is recommended to use the one that has been prepared. In these adhesives, the ratio of the total amount of epoxy groups to the total amount of (meth)acryloyl groups is 9
5 to 60%, <meth)acryloyl group 5 to 40%
It is best to create it so that Hopefully epoxy group 90
to 80%, (meth)acryloyl group 10 to 20%
is appropriate.

Examples of epoxy base agents include bisphenol A, bisphenol F, and novolak.

or by adding a reactive diluent, which is a low viscosity epoxy.

It is better to use one without adding it. When the content of the reactive diluent increases, the viscosity of the adhesive decreases and workability improves, but the heat resistance of the adhesive layer decreases.

It is better to limit the amount of addition as it will reduce the reactivity and deteriorate the properties of the adhesive layer.

Epoxy curing agents include acid anhydrides, aromatic amines, aliphatic amines, amides, etc. Among them, those with a pot life of 1 to 50 hours at room temperature are best used.
It is preferable to select a curing agent that can be cured at a temperature of 80°C to 80°C. Examples include 2-ethyl-4methylimitazole, 1
Examples include imidazole series such as -benzyl-2-methylimidazole and 1-isobutyl-2-methylimidazole, and cycloaliphatic amines such as menthanediamine.

As the main ingredient of the ultraviolet curable resin, it is best to use one that has a relatively low viscosity at room temperature and one that is highly reactive; examples include 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, There are neopentyl glycol diacrylate, dipentaerythritol hexaacrylate, tripropylene glyfur diacrylate, etc., and these should be used as the main ingredients.

As an example of the curing agent for the ultraviolet curable resin, one that absorbs at wavelengths longer than 3000 m is used. Examples include benzyl dimethyl ketal, 1-hydrobaf dicyclohexyl phenyl ketone, 2-methyl-[4-(methylthio〉phenyl]-2-morpholino-1-propanone, benzoin, benzone ethyl ether, benzoin isobutyl ether, 1-(4-Inpropylphenyl)-2-hydroxy-2-methylpropan-1-one 2hydroxy-2-methyl-1-phenylpropan-1-one, 3
, 3-dimethyl-4-methoxybenzophenone and the like.

In the present invention, the temperature at the time of bonding needs to be changed depending on the viscosity of the adhesive, and is preferably higher than room temperature, but is preferably 70° C. or lower in order to make it easier to obtain a constant constant temperature. More preferably from 40°C to 60°C
It is ℃. The substrate heating for curing the adhesive is preferably from 40°C to 80°C, depending on the curing temperature of the adhesive. More preferably it is 50°C to 70°C.

In the present invention, as for the mixing ratio of epoxy and ultraviolet curable resin, the higher the mixing ratio of epoxy resin, the better the properties as an adhesive, and the ratio of epoxy and ultraviolet curable resin is 95
:5 to 70:30 is preferable. Here, epoxy refers to an epoxy main ingredient and a curing agent, and an ultraviolet curable resin refers to an ultraviolet curable resin in which an organic peroxide is added to the main ingredient and a curing agent.

In the present invention, if the bonding is performed under reduced pressure, the adhesive can be easily degassed and air bubbles are difficult to be incorporated into the adhesive layer.

In the present invention, it is preferable that the time for which the disks are left to stand after being bonded together and temporarily fixed by irradiation with light is set to be longer than the time for the adhesive to naturally harden. For example, if you leave it alone for 50
In the case of bonding with an adhesive that completely loses fluidity and hardens over time, it is better to set the time to 50 hours or more.

In the present invention, it is preferable that the ultraviolet curable resin layer formed on the outer circumferential side of the optical disk be blended in such a way that it can improve adhesion to the substrate material. For this purpose, the UV curable resins used include acrylates such as polypropylene glycol and polyethylene glycol, as well as low viscosity acrylates such as 1.6
-Addition of hexanediol diacrylate, trimethylolpropane triacrylate, etc., coupling agents such as silane coupling agents, titanium coupling agents, etc., or oligomers such as urethane acrylate, epoxy acrylate, etc. can also be used as substrates for cured products. Increase adhesion to the material.

[Effects of the Invention] As described above, according to the optical disc manufacturing method of the present invention, since the adhesive layer of the disc is epoxy-based, the mechanical properties of the optical disc do not change even at high temperatures. Furthermore, since the outer periphery is covered with an ultraviolet curable resin, there is a strong adhesion to the resin substrate, and there is no possibility that the ceramic will be peeled off from the substrate due to falling and recording and reproduction will not be possible.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of an optical disc according to the present invention. FIG. 2 is a schematic diagram of the optical disc manufacturing method of the present invention. 1.7... Polycarbonate substrate 2.8...
Protective layer 3.9 of S jAIN Recording layer 4 of NdDyFeCo, lO.
...S 1AIN protective layer 5.11...Al-Ta-
31 layer 6...Adhesive layer 12.13...Hard coat layer 14.15...Antistatic layer I6...UV curing resin part 17... - Formed on the outer periphery of the disk Groove 18・
...Ultraviolet curing resin part 19 filled to fill the groove...High pressure mercury lamp 20...Above the part where the outer periphery has been cut

Claims (2)

[Claims] (1) An optical disc characterized in that a resin substrate used in the optical disc is formed so that a groove is formed on the outer circumference side when the resin substrates are bonded together. (2) The resin substrate is formed with grooves or pits for tracking, and a first ceramic layer, a recording layer, a second ceramic layer, and a reflective layer are arranged on the side of the resin substrate on which the grooves or pits are formed, in this order. The sequentially formed films are pasted together using epoxy resin, the epoxy resin is cured, the grooves formed on the outer periphery are filled with an ultraviolet curable resin, and the ultraviolet curable resin is cured. A method for manufacturing an optical disc, characterized by cutting the outer periphery.