JPH0227538A - Both-face optical disk - Google Patents

Abstract

PURPOSE:To prevent the erosion of formed substrates and thin metallic films by adhering two sheets of disks consisting of the thin metallic film layers formed on transparent substrates between the thin metallic film layers by a specific resin adhesive agent. CONSTITUTION:The grooves and bits for signals on the transparent substrate 100 are formed by injection, etc. Transparent materials such as acrylic resin, polycarbonate resin and glass are usable as the transparent substrate 100. The thin metallic film layer 102 as a reflecting film and recording layer is formed on the transparent substrate 100 on the surface on which the grooves and bits of the substrate 100 are formed. Al, etc., are used as the reflecting film for this thin metallic film 102 and Bi, Te, Ta, etc., or the alloys thereof are used as the recording film. Two sheets of such disks are adhered between the thin metallic film layers 102 and 102 by the low-viscosity fast setting epoxy resin adhesive agent 104 essentially consisting of a bisphenol A type epoxy resin. The erosion of the formed substrates and thin metallic films by an org. solvent or heat generation at the time of adhering is prevented in this way.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides two disks each having grooves and/or signal pits formed on one side, with the grooves and/or signal pits facing inside. The present invention relates to a double-sided optical disc formed by joining the discs in the same state, and particularly to an improvement in the joining means thereof.

[Prior Art] A double-sided optical disc is an optical disc in which grooves and/or signal pits are formed on both sides of the disc, and various types have been proposed in the past.

FIG. 2 is a sectional view of a double-sided optical disc proposed in Japanese Patent Application Laid-Open No. 62-75947, and this double-sided optical disc is constructed by pasting a pair of discs together. The disk has a recording layer 2 formed with grooves and/or signal pits.
A transparent first base material 4 provided on one side and a transparent second base material 6 without a recording layer, with the recording layer 2 on the inside, and a spacer 8. between the base materials 4 and 6. The recording FJ 2 and the second base material 6 are pasted together with an air layer 11 formed at 10, or the recording FJ 2 and the second base material 6 are pasted together with a protective material interposed therebetween, and the disk is bonded between the base materials 6, 6. It is pasted together with adhesive 12.

Since this double-sided optical disc is constructed as described above, it is possible to inspect the discs at the disc stage and take out only non-defective discs and combine them, thereby increasing the yield of finished products. Furthermore, since this double-sided optical disc is constructed by laminating two discs together, its strength can be increased and warpage and surface separation can be reduced.

FIG. 3 is a sectional view of a double-sided optical disc proposed in Japanese Patent Application Laid-open No. 61-15185. Reflection provided on the surface where the signal pit 14 is formed! 11B and protection 111120 provided on 1 reflection gta. Anaerobic curing for 20.20 hours! ! ! It is bonded with an adhesive 22.

The reflection l118 is made of an A2 vapor deposited film, and the protective film 20 is UV
Made of hardening acrylic resin. The anaerobic curing adhesive 22 is a type of adhesive that polymerizes when air is blocked, such as anaerobic curing adhesive (for example, "Arontite R (registered trademark) J" manufactured by Toagosei Kagaku Kogyo ■), j!! UV curable adhesive (e.g. rTB3 manufactured by Three Bond ■)
060 (registered trademark).

Since this double-sided optical disk is constructed as described above, the product can be manufactured in a short time at room temperature, almost no thermal strain or other stress is applied, no warping of the substrate occurs, and the surface coated with adhesive is The shape of the signal pit can be maintained with high accuracy without being damaged.

FIG. 4 is a cross-sectional view of a double-sided optical disc proposed in Japanese Patent Application Laid-open No. 120357/1983. This double-sided optical disc has a recording layer 2B formed on a molding layer 26 on a transparent substrate 24, and a pair of discs. Then, a radiation-curable adhesive containing monofunctional vinyl chloride is applied and cured on the recording layer 28 of one or both disks to form an adhesive layer 30, and each recording layer 28, 28 is placed facing each other. It is made by pasting both of the above discs together.

In the molding layer 26, a photopolymer (ultraviolet curing resin) is applied onto the transparent substrate 24, and grooves and/or pits are molded using the PP method. The recording layer 28 is made of Bi on the molding layer 26.
, In, Te, AI, Sn, or other metals are vapor-deposited. The adhesive layer 30 is made by applying, for example, an ultraviolet curable adhesive containing functional vinyl nitride using a spin cord or the like.
Formed by irradiation with ultraviolet light.

By configuring this double-sided optical disk as described above, it is possible to reduce one process compared to the conventional process, which is advantageous in terms of manufacturing cost. This prevents deterioration of characteristics due to accumulation of dust contamination.

FIG. 5 is a sectional view of a double-sided optical disc proposed in Japanese Patent Application Laid-Open No. 61-66239.
A molding layer 34 is formed on one surface of the transparent substrate 32, a metal recording film 36 is formed on the molded FJ34, and a metal recording film Ql! l
A photocurable resin layer 3B is formed on the photocurable resin layer 36, and a plastic film layer 40 is further formed on the photocurable resin layer 38 to form a disc. Two discs are formed, the plastic film layer 40 is placed on the inside, and an adhesive is applied. It has a structure in which the layers are laminated and fixed together with the layer 42.

Grooves and/or signal pits are formed in the molding layer 34 using the PP method. The metal recording layer 1!936 is deposited on the molding layer 34 to form a layer. The plastic film 40 is for protecting the recording layer, and the photocurable resin layer 38
Apply UV light on top. The disks are bonded together with the plastic film layers 40 facing each other using a low-temperature curing adhesive and a resin that exhibits tackiness at room temperature or below 120°C.

By having the above-mentioned structure, this double-sided optical disc has fewer errors in the initial stage and after the moisture resistance test compared to the conventional example. Because there is no heat, high quality can be achieved initially, and the adverse effects of high-temperature conditions can be minimized.

FIG. 6 is a cross-sectional view of an optical disc proposed in Japanese Patent Application Laid-Open No. 61-50232. This double-sided optical disc consists of a transparent molded substrate 46 on which a metal marking @@44 is formed, and an adhesive layer 48 on one side. The formed plastic film 50 and
A metal recording film 44 and an adhesive layer 48 are bonded together so as to be in contact with each other.

The adhesive of the adhesive layer 48 is, for example, a light-curing J# resin, a hot-melt adhesive, a high-performance adhesive, a fast-curing epoxy σ-1 resin, a urethane resin, or a fast-curing acrylic adhesive. , an unsaturated polyester resin, or an ultraviolet curable adhesive is used to protect the surface of the metal recording film 44 of the molded substrate 46 from now on. * When a highly flexible plastic film 50 is used as m, no bubbles or peeling defects occur, and the substrate is less likely to warp.

[Problems to be Solved by the Invention] In the conventional optical disc as described in -1-, when an adhesive using a solvent 2, for example, an adhesive in which rubber is dissolved in an organic solvent, is used to bond the disc, the molded substrate or thin metal films are attacked by organic solvents, and when hot melt adhesives or UV curing adhesives are used, the heat and ultraviolet rays applied! ! ! The heat generated during irradiation can corrode the gold 111 thin film and cause warping of the substrate, etc., so be sure to keep it safe when using adhesive! There was a problem in that an I-limb had to be provided.

In addition, epoxy resin adhesives and urethane S4 resin adhesives take a very long time to form into 1 layer, taking more than 24 hours at room temperature, and productivity is extremely low when using such adhesives. It will get worse, and if you use viscous or M agent, 2
There were problems in that it could not hold a single disc for a long period of time and had poor weather resistance.

Furthermore, when a fast-curing type UV curing type 1121 agent is used for adhering the disks, there is a problem that distortion occurs due to bonding and warping of the optical disk occurs.

[Means for Solving the Problems] The name of the present invention is based on the results of studying various adhesives for the above-mentioned problems. When using an adhesive made of fast-curing epoxy resin, it will not attack the fi, type 1IIIi plate or thin metal film, will not cause warping of the substrate, etc., can be attached in a short time, and has excellent weather resistance. This discovery led to the present invention.

That is, the double-sided optical disc according to the present invention includes a transparent substrate made of synthetic #l# resin on which grooves and/or signal pits are formed, and a transparent substrate having a shape of 1. By adhering two disks consisting of a metal thin film layer between the metal thin SS0 with a low viscosity fast-curing epoxy resin adhesive mainly composed of bisphenol/IJ epoxy mm, J:Note 51! This problem was solved.

The grooves of the transparent base @J:: and the signal pits are formed by the PP method or injection. As the transparent substrate, transparent materials such as acrylic resin, polycarbonate-1/WIWJ, glass, etc. can be used.

A reflective film and a metal thin film layer as the M layer are formed on the transparent substrate. The metal thin film layer is formed by vacuum vaporization or sputtering on the surface of the transparent substrate on which the grooves and pits are formed. The metal thin film layer is made of anti-Ill tumor and 1) using AI etc., and the recording film and 1) is made of Bi.

Alloys such as Te, Ta, etc. or 6:, I″l, etc. can be used.

Low viscosity, room temperature fast curing epoxy resin adhesive has a viscosity of 6OO
~aOocps/20℃, curing time 15-18 minutes/
2 [Fast-curing epoxy resin with low viscosity of 1℃”
It is.

The adhesive is applied using a spinner and M4 resin in concentric circles, the disk tt to be bonded is placed on top of the adhesive, and pressure is applied using a press or the like to bond the disk.

This adhesive does not use solvents! It does not attack the substrate, etc. Also, heat generation during curing is minimized, distortion after curing is small, weather resistance is good, and there is no effect on the disk. Moreover, it is excellent in mass production and low cost.

[Example] 1 example-1 A groove and/or a signal pit is formed on one side 1, 12
Two acrylic resin disks are made by injection molding, and each of the two disks has a groove and/or a signal pit formed thereon. A thin metal film layer is formed by vapor deposition, and then a low viscosity, room temperature fast curing agent, boxy@fat binder (ALTECOEPOXY F) is applied to the metal thin film layer.
X-50 (1; 11117 Lua 7 techniques 11111)
・Coat and overlap these metal thin film layers 1!゛te 2
Two discs were glued together.

ALT using adhesive: Go EPOXY F
X-50077) The characteristics are as follows.

Two-component mixture type (mixing ratio 100:100) ・Main ingredient: Modified epoxy resin (bisphenol A type epoxy resin, reactive diluent) ・Curing agent: Modified polythiol (ester, polymercaptan with ester bond, tertiary amine) ・It cures quickly at room temperature and has excellent water and humidity resistance.

・Viscosity: 600 cps/2G°C, curing time: 15 minutes at 720°C. Figure 1 is a cross-sectional view of the double-sided optical disc produced in this way. In Figure 1, 100 is a transparent substrate on which grooves and/or signal pits are formed. , 102 is a metal thin film layer formed on the surface of the transparent substrate 100 on which the grooves and signal pits are formed, and 104 is an adhesive layer bonding the metal thin film layer 102.

On the other hand, as a comparative example, a chloroprene rubber solvent type adhesive (manufactured by Semedaishin 5F5 Semeda 12) was applied to the metal thin film layer of two disks formed in the same manner as above, and the two disks were bonded together.

A double-sided optical disc for comparison was obtained.

When both of these double-sided optical discs were observed 24 hours after adhesion, no changes were observed in the double-sided optical disc of the present invention, but fine cracks were observed on the surface of the metal 5w1i layer in the double-sided optical disc of the comparative example. and
This metal thin 1IJl! Due to the damage, normal playback of the optical disc is impossible.

This seems to be because the adhesive used in the present invention does not use a solvent, whereas the adhesive in the comparative example uses a solvent.

Dog m In the same manner as in Example 1, four acrylic resin disks were prepared on which a metal thin film layer was formed on the surface on which grooves and/or signal pits were formed. Two of these discs have low viscosity, mainly made of bisphenol A epoxy resin.
Rapid curing epoxy resin adhesive at room temperature (Diabond DE39
6; manufactured by Nogawa Chemical ■) was applied, and the metal thin film layers were made to face each other to obtain a one-sided double-sided optical disk.

The properties of Diapond DE316 used as an adhesive are as follows.

Two-component mixed type (mixing ratio 100 near 0) / Main ingredient: Bisphenol A epoxy resin, polyethylene glycol diglycidyl ether / Hardening agent: Has a tertiary amine / epoxy polymer capto-based SH group .

Low viscosity room temperature curing type with excellent water and moisture resistance.

・Viscosity 600-800cps/20℃, curing time 18
min/20° C. As a comparative example, a hot melt type adhesive was applied to the metal thin film layer of the remaining two disks by a roll coater method, and these were overlapped and bonded to obtain a single-sided optical disk.

The signals recorded on the double-sided optical discs of these Examples and Comparative Examples were reproduced by an optical disc player at a rotation speed of 1800 rpm.The optical discs of the present invention did not cause any trouble in reproduction, and the disc surface measured afterward. It was confirmed that the warpage was also extremely small. On the contrary,
In the optical disc of the comparative example, although the two discs before being pasted together were exactly the same as those used in the present invention, a collision between the optical disc and the pickup occurred during playback, and the playback was delayed. A phenomenon was observed in which it became difficult to

The optical disk of this comparative example was warped, which was thought to be due to deformation due to the effects of heating during adhesion, and it is thought that this caused the aforementioned collision between the optical disk and the pickup. In contrast, the adhesive used in the present invention minimizes heat generation during curing, has little distortion after curing, has good weather resistance, does not affect the disk, and is also suitable for mass production and low cost. It's an excellent thing.

By the way, in the above embodiments, the focus has been given on write-once optical discs, but it can also be applied to audio discs (CDs), video discs (LDs), CD graphics, and double-sided optical discs that have the durability, high playback, and high recording performance of rewritable optical discs. Of course, it can also be used. In addition, the present invention can also be applied to lamination of functional films, etc.
It is not limited to.

[Effects of the Invention] Since the present invention uses a low-viscosity, fast-curing epoxy resin whose main component is bisphenol A-type epoxy resin, the molded substrate and metal thin film are less likely to be eroded by organic solvents or heat generated during adhesion. It has the effect of preventing

In addition, the low viscosity, fast-curing epoxy resin cures quickly at room temperature and has a low viscosity, so productivity is good and costs can be reduced, and since a hardening agent is used, there is no distortion or warping of the disk.

Furthermore, since the low-viscosity, fast-curing epoxy resin can directly bond the recording layers together, there is no need to provide a protective film to protect the recording layer, and it also has good weather resistance.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing one embodiment of the present invention, Figures 2 to 6
The figure is a cross-sectional view of a conventional optical disc. 100--------...Transparent substrate, 102--
-----------Metal thin film layer, 104------
------・Adhesive layer.

Claims (1)

[Claims] Two disks each consisting of a transparent substrate made of synthetic resin on which grooves and/or signal pits are formed, and a metal thin film layer formed on the surface of the transparent substrate where the pits are formed, are 1. A double-sided optical disc characterized in that the double-sided optical disc is bonded with a low-viscosity, fast-curing epoxy resin adhesive containing bisphenol A type epoxy resin as a main component.