JPH03183041A - Optical disk - Google Patents

Abstract

PURPOSE:To improve corrosion resistance and to prevent a film from being pealed off by the change of a temperature and humidity by forming adhesive layers where define bisphenol epoxy resin is as a main agent and modified aliphatic polyamine is as a curing agent, on a recording layer, facing the adhesive layers to each other and adhering the adhesive layers to the recording layer with an adhesive layer whose hardness is smaller than that of this adhesive layer. CONSTITUTION:On a transparent base 1, an SiNx enhancing layer 2, TbFeCo recording layer 3 and SiNx layer 4 are formed by sputtering and then, after executing spin coat to an adhesive layer 5, the layer 5 is left at a room temperature to be cured. Afterwards, an adhesive layer 71 whose hardness is smaller than that of the layer 5, is applied by a roller and disks are matched, pressurized and stuck together. Thus warping deformation is decreased and the corrosion resistance is increased. Then, the film is prevented from being pealed off even in the case of the changes of the temperature and humidity and the mechanical strength is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc on which information is recorded and reproduced using light.

[Prior Art] Fig. 4 is a cross-sectional view of a conventional optical disc disclosed in, for example, Japanese Patent Laid-Open No. 83-67258, and in Fig. 1, (6)
is a single plate disc, and (7) is an adhesive layer. Prior to this publication, heat-curing or light-curing adhesives were used for this adhesive layer. However, when bonding adhesives such as heat or light-curing adhesives, a considerable amount of heat is applied and distortion remains in the disk, resulting in deformation and warping, and corrosion occurs and grows during long-term use, resulting in a lack of reliability. was there. Therefore, as shown in the above-mentioned publication, a method of applying a thermoplastic adhesive with a roller was proposed. With this method, the time required for the process can be significantly shortened, and the heat applied to the disk is only applied to the surface for a few seconds when the heated roller comes into contact with the disk, and is immediately dissipated, so the heat applied to the plastic substrate is extremely small. Therefore, an optical disc with less distortion and therefore less deformation and warping can be obtained. However, if the adhesive is applied directly to the surface on which the film is formed, the film may peel off during application, and the film may easily peel off due to changes in environmental temperature and humidity.0Various thermoplastic adhesives When we conducted a temperature/humidity cycle test as shown in JIC-C5024 (Method I) on disks that were bonded together by applying the agent directly to the recording film, peeling occurred on the entire surface of the disks during the IO cycle, and I ! As shown in the characteristic diagram of the change in bit error rate depending on the number of cycles in Figure 5, the pit error rate also increased significantly. Therefore, as disclosed in Japanese Patent Application Laid-Open No. 63-87631, a measure was taken to form an ultraviolet curable adhesive film on the recording film.

[The problem that the invention tries to solve! ] However, the adhesive film formed on the recording film directly protects the recording film, and is required to have high corrosion resistance, to exhibit as little stress as possible to the easily deformable resin substrate, and to be resistant to changes in environmental temperature and humidity. On the other hand, it is necessary to prevent the occurrence of peeling of the film, but the above-mentioned conventional adhesive film does not satisfy the above-mentioned conditions.

This invention has been made to solve the above problems. 1. A highly reliable optical disk with reduced warping deformation, high corrosion resistance, prevention of film peeling even with changes in temperature and humidity, and excellent mechanical strength. The purpose is to obtain.

[Means for Solving the Problems] The optical disc of the present invention includes a recording layer provided on each transparent substrate,
Each recording layer is provided with a first adhesive layer consisting of a cured product of a room temperature-curable two-component epoxy resin containing a bisphenol type epoxy resin as the main agent and a modified aliphatic polyamine as a curing agent, and a first adhesive layer of each transparent substrate. The layers are opposed to each other and are interposed between the first adhesive layers, and the second adhesive layer has a hardness smaller than that of the first adhesive layer.

[Function] In the present invention, by using a cured product of a room temperature-curable two-component epoxy resin in which a bisphenol-type epoxy resin is used as the main principle and a modified aliphatic polyamine as a curing agent in the first adhesive layer, warping deformation is reduced. It has high corrosion resistance and prevents film peeling even with changes in temperature and humidity, and by using a material with a hardness smaller than that of the first adhesive layer for the second adhesive layer, the first
The adhesive layer formed from the second adhesive layer becomes relatively soft and has excellent mechanical strength.

[Example] FIG. 6 compares an example of the present invention and a comparative example.

It is a characteristic diagram showing the amount of increase in the glide angle of a single-plate optical disk in which the first adhesive layer is formed of various resins.
iNxjl-enhancement layer, TbFeCo magnetic layer, S
i In Figure 1, which shows the amount of increase in the warp angle of the disc that occurred after forming various resin layers on an optical disc plate on which the Nx layer was left by sputtering, A, B, and C indicate that the first adhesive layer was a room-temperature curing type. This product uses two-component epoxy resin, and the basic rule is A.
, a, ccl~3) is bisphenol type A, A(4,5
) is bisphenol F type epoxy resin, and the curing agent is A(1
~5) are modified aliphatic polyamines with different viscosities, and B(+
"3) is polythiol, C (1-3) is polyamide amine, D (1-3) is thermosetting epoxy two-component resin, E
(1 to 3) are UV-curable resins, F (1 to 3) are low viscosity hot melt resins, and G (1 to 3) are cases where a fluorine-based coating agent is used.

Note that the vertical axis is the increase in warpage angle: t (mrad), and the horizontal axis is the type of resin. Because a considerable amount of heat is applied to the disk, large warping deformation occurs.

Those with small warpage (A, B, C, F, G) were used as the first adhesive layer and were laminated with thermoplastic resin to produce an optical disk, and these were placed in an atmosphere of 60°C and 90% RH. In Figure 7, which is a characteristic diagram showing the change in the number of corrosions that occurred after 1,000 hours of use in a plastic container, depending on the type of resin used for the first adhesive layer, the vertical axis is the number of corrosion occurrences, and the horizontal axis is the number of corrosion occurrences. This is the type of resin of the first adhesive layer. According to it, the internal curing agent of epoxy resin is a modified aliphatic polyamine (
A large amount of corrosion occurred except for A+~As), a part of the thermoplastic resin (Fl), and the fluorine-based quick-drying resin (G+~G3).

Therefore, among the optical discs mentioned above, those with a small number of corrosion occurrences were subjected to the Z/AD test (JIS-C5
024) 10 cycles were performed. Figure 8 shows the results. In Figure 8, which is a characteristic diagram showing the change in the number of film peeling (blister) occurrences depending on the type of resin used for the first adhesive layer after the heat cycle test, the vertical axis is the film peeling (blister). blisters) number of occurrences,
The horizontal axis indicates the type of resin of the first adhesive layer.

According to this study, many membrane peelings occur in thermoplastic resins.
Although some peeling occurred even with fluororesin, a room-temperature-curing epoxy resin using a modified aliphatic polyamine as a curing agent showed the best results in a series of tests.

The first adhesive layer is made of a cured product of a room temperature curable two-component epoxy resin using the bisphenol type epoxy resin according to the present invention as the main agent and a modified aliphatic polyamine as the curing agent.
For example, with a two-component epoxy resin manufactured by ThreeBond, bisphenol A type epoxy resin (product name: I 2022C) is mixed with this agent, modified aliphatic polyamine (product name: I 2131 D)
) is used as a curing agent, bisphenol F type epoxy resin (trade name: I2023) is used as the present agent, and modified aliphatic polyamine (trade name: #21310) is used as a curing agent.

As the second adhesive layer having a hardness lower than that of the first adhesive layer according to the present invention, for example, silicone rubber, thermoplastic resin, etc. are used.

Embodiment 1 FIG. 1 is a sectional view of an optical disk according to an embodiment of the present invention, in which (1) is a transparent substrate made of, for example, polycarbonate, and (2) is a transparent substrate made of polycarbonate, for example.
) is a SiNx enhancement layer, and (3) is, for example, TbFeC.
o recording layer, (4) is a SiNx layer, (5) is a first adhesive layer of, for example, epoxy resin, (6) is a single plate disk, (71
) is the second adhesive layer. In this example, the first adhesive layer (5) is ThreeBond! ! A 12-component epoxy resin, bisphenol A type epoxy resin (trade name: I2022C) was used as the main agent, and modified aliphatic polyamine with a viscosity of 100 cps (trade name: I21310) was used as the curing agent, each at a mass ratio of 3:1. The second adhesive layer (71
) as a thermoplastic resin (product name: MTIMELD XT
-1370E (manufactured by Mitsui Toatsu Chemical Co., Ltd.) was used. That is, a SiNx enhancement layer (2), a TbFeCo recording layer (3), and a SiNx layer (4) are formed on a transparent substrate (1) by sputtering, and then a first adhesive (5) is applied at 300 Or@p for 2 minutes. After spin-coding, the second adhesive was cured by being left at room temperature for 20 hours, and as shown in FIG. Then, a second adhesive layer (71) is provided. In Fig. 0, an optical disk according to an embodiment of the present invention was obtained by pressing and bonding the disks provided with the second adhesive layer, (1) is a melting tank, (12) is a thermoplastic resin agent, (13) ) is a coating roller, (14) is a veneer disk provided with up to the first adhesive layer, (15) is a feed roller, and (16) is a conveyor. The characteristics of the optical disc of the example were measured. The warpage angle of the disc measured with the disc up to the first adhesive layer is 1
．． At 7 mrad, the increase from 1.1 mrad after sputtering is as small as 0.9 mrad, and after bonding with the second adhesive layer, the disk was heated to 60°C and 90% RH for 1000 mrad.
No corrosion occurred even after the test was carried out for a long time, and there was no change in pit error rate or CNR. Furthermore, JIS-C50
No film peeling occurred after 10 cycles of the temperature/humidity cycle test according to Method I.24 (Method I), and changes were observed in the CNR and pit error rate as shown in the characteristic diagram showing changes in pit error rate depending on the number of cycles in Figure 3. A highly reliable optical disc was obtained.

Example 2 In Example 1, as the second adhesive layer (5), bisphenol F type epoxy resin (product name: # 2023), a two-component epoxy resin manufactured by ThreeBond, was used as the present agent, and modified aliphatic polyamine (product name: #) was used as the second adhesive layer (5). An optical disk of another example of the present invention was obtained in the same manner as in Example 1, except that a mixture of 21310) and 21310) was used as a curing agent in a gL ratio of 3:1.

Next, the characteristics of the optical disc of another example of the present invention obtained as described above were measured. The warp angle of the disc measured with the disc up to the first adhesive layer is 1.5 mr.
The amount of increase in ad from 1.1+arad after sputtering is only 0.4 mrad, which is smaller than that in Example 1.

This is because the viscosity of this agent is bisphenol A epoxy resin (
Bisphenol F type epoxy resin (#2023) has 900 cps compared to 13,000 cps for 2022).
This is thought to be due to the small ps and the thin film formed during the spin code. On the other hand, even if the thickness of the resin layer of the first adhesive layer is small, it is
After charging for 0 hours, the characteristics after 10 cycles of a greenhouse temperature cycle test according to JIS-C5024 (method ①) were good, and there was no change in pit error rate and CNH.

In the above embodiments, the second adhesive layer (71) is not limited to a thermoplastic adhesive, since the first adhesive layer (6) exhibits good properties, and the adhesive resin itself is highly reliable. Any adhesive may be used, but a thermoplastic adhesive is best in consideration of the damping characteristics of the disk and workability.

[Effects of the Invention] As explained above, the present invention includes a recording layer provided on each transparent substrate, a room-temperature-curing two-component material provided on each recording layer, and a bisphenol-type epoxy resin as a main principle and a modified aliphatic polyamine as a curing agent. A first adhesive layer made of a cured product of a transparent epoxy resin and a first adhesive layer of each transparent substrate are placed opposite to each other and interposed between the first adhesive layers, and a second adhesive layer having a hardness smaller than that of the first adhesive layer is provided. By using such a disc, it is possible to obtain a highly reliable optical disc with reduced warping deformation, high corrosion resistance, prevention of film peeling even under changes in temperature and humidity, and excellent mechanical strength.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an optical disc according to an embodiment of the present invention, FIG. 2 is a configuration diagram showing a state of application of a second adhesive according to an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a cross-sectional view of a conventional optical disk, FIG. 5 is a characteristic diagram showing pit error rate changes depending on the number of cycles of a conventional optical disk, and FIG. A characteristic diagram showing the increase in warp angle of a veneer disk in which the first adhesive layer is made of various resins, which compares an example of the present invention and a comparative example. Fig. 7 compares an example of the present invention and a comparative example. An optical disc bonded with thermoplastic resin is placed in an atmosphere of 60°C and 90% RH.
A characteristic diagram showing the change in the number of corrosions that occurred after 000 hours of use depending on the type of the first adhesive layer. Figure 8 shows film peeling 1 after a heat cycle test comparing an example of the present invention and a comparative example.
1 is a characteristic diagram showing a change in the number of occurrences of blisters depending on the type of the first adhesive layer. FIG. In the figure, (1) is a transparent substrate, (3) is a recording layer, and (5) is a transparent substrate.
) is the first adhesive layer, (6) is the veneer disk, and (71,) is the second adhesive layer. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] A recording layer provided on each transparent substrate, and a first adhesive layer provided on each recording layer and made of a cured product of a room temperature-curable two-component epoxy resin using a bisphenol type epoxy resin as the main agent and a modified aliphatic polyamine as a curing agent. , and the first of each transparent substrate
the adhesive layers facing each other and interposed between the first adhesive layers;
An optical disc comprising a second adhesive layer having a hardness lower than that of the first adhesive layer.