JPH0411337A - Optical disk - Google Patents

Abstract

PURPOSE:To prevent tracking errors of laser light and generation of errors on use by successively forming a surface hard film which transmits laser light and an antistatic film comprising silicon oxide or a resin mixed with a conductive powder on the laser incident side of a substrate. CONSTITUTION:On the laser incident side of a plastic optical disk substrate 1, there are successively formed a surface hard film 4 which transmits laser light and an antistatic film 5 comprising silicon oxide or a resin mixed with a conductive powder. Namely, the surface hardness of the plastic optical disk substrate is improved by the surface hardening film 4, while deposition of particles floating in air is prevented by the antistatic film 5 formed on the film 4. Thus, the obtd. disk is free from tracking errors of laser light or generation of errors on use.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to an optical disc. More specifically, the present invention relates to surface treatment of optical disc substrates.

(B) Conventional technology Conventionally, as the demand for optical disks increases, the electrostatic charge during operation causes airborne particles to adhere to the surface of the disk, and scratches caused during handling may cause laser track misalignment or errors, and the characteristics of the disk. The problem has arisen that the performance of the optical disc cannot be fully demonstrated due to the deterioration of the optical disc. Therefore, recently, as shown in Fig. 2, a magneto-optical recording film 2 and a protective film 3 for the recording film are formed on one surface of a plastic optical disk substrate l, and then the other surface (the surface on the laser incidence side) is formed. ), a countermeasure has been taken in which an antistatic resin obtained by mixing a UV curable resin with a surfactant is uniformly applied by a method such as a spin code method to form a surface treatment@6. Also,
Measures have also been taken to prevent the performance of the previous disk from deteriorating by wiping off the deposits on the surface of the disk.

(c) Problems to be Solved by the Invention However, in the case of an antistatic film formed by mixing a surfactant with a UV curable resin, the antistatic effect will be poor if the mixing ratio of the surfactant to the UV curable resin is high. If the surfactant is too thick, the surface hardness will decrease and the surface will be more likely to be scratched.On the other hand, if the mixing ratio of surfactant is low, the surface hardness will improve but the antistatic effect will be small, and the antistatic performance and surface hardness will be reduced. The problem was that I could not satisfy them at the same time.

Furthermore, when conventional optical discs are exposed to high temperature and high humidity environmental conditions such as 80°C and 90% RH, the surfactant oozes out onto the surface, or moisture adheres to the surfactant and forms water droplets. There was a problem with long-term stability.

The antistatic film based on silicon oxide has good antistatic performance, but the film itself is hard and cannot be made thick, so when applied to soft plastics, the surface hardness is not sufficient, and it is difficult to resist at low temperatures. There is a problem in that cracks occur on the surface when a high temperature cycle test is performed.

This invention was made in order to solve the above problems, and provides an optical disc that has a surface that is highly hard, scratch resistant, and does not generate electrical charge, and that does not cause the laser to go off track or cause errors during operation. This is what we are trying to provide.

(d) Means for Solving the Problems According to the present invention, a hard surface film that allows laser light to pass through and a silicon oxide-based or conductive film on the side of the plastic optical disc substrate intended for laser incidence. An optical disc is provided in which powder-mixed resin-based antistatic films are sequentially laminated.

The plastic optical disk substrate may be a plastic plate or a plastic plate having a laser beam recordable film and a protective film formed on its surface.

The plastic plate can be made of laser-transmissive plastic, such as polycarbonate, polymethyl methacrylate, amorphous polyolefin, or the like. The dimensions are typically 80 to 300 mm in diameter and 1.2 mm in thickness. The above-mentioned laser light recordable film is, for example, A I N/
D y F e Co/AIN/Al5AIN/GdT
It can be formed using a magneto-optical recording film such as bFe/AIN/A1. The protective film can be formed using, for example, an acrylic urethane UV curable resin, an acrylic UV curable resin, or the like.

The surface hardness film in this invention is intended to prevent scratches from occurring on the surface of the substrate on which the laser is incident, and usually has a pencil hardness of 88 or more on the surface of the substrate on which the laser is intended to enter. It is also possible to use a stack of films. The lamination of this surface-curing film is, for example, acrylic urethane-based U
V5F resin, acrylic UV5! This can be done by applying a chemical resin or the like to the surface of the substrate by a spin code method or the like and curing it. The thickness of this film is usually preferably 05 to 10 μm. If the film thickness is less than 0.5 μm, it is not preferable because scratches on the substrate surface cannot be prevented. 20
If it exceeds .mu.m, the film quality will become non-uniform, which is not preferable.

The antistatic film in this invention is intended to prevent airborne particles from adhering to the surface of the substrate (optical disk), and is suitably a film that has antistatic properties, light transmittance, and durability, and is made of silicon oxide. A conductive powder-based antistatic film or a conductive powder mixed resin-based antistatic film can be used by coating and curing the above-mentioned surface hard film. This film thickness is usually 0.01 to 0.
The thickness is preferably 2 μm. The silicon oxide antistatic film can be made of a 5i-0 chain or SiO network compound, and can be prepared by applying a colloidal solution of silicon oxide and drying it. Further, the conductive powder mixed resin antistatic film has an average particle size of 001 to 0.4, for example.
Conductive powder of μm tin oxide, indium oxide, antimony oxide, etc., for example, acrylic urethane UV curing resin,
It can be used by mixing it with a grain material such as an acrylic UV curable resin to prepare a coating liquid, and applying this coating liquid onto the above-mentioned surface hardening film and curing it.

(e) The hard surface film improves the surface hardness of the plastic optical disk substrate, and the antistatic film formed thereon prevents airborne particles from adhering. At this time, the surface hardness of the plastic substrate is improved by the surface hardness film, and the antistatic effect can be achieved by the antistatic film. Both improvements can be made at the same time without conflicting performance improvements.

Furthermore, since the antistatic film used in the present invention is not surfactant-based, it is stable over a long period of time, and even if a silicon oxide-based antistatic film is formed on a plastic substrate and a silicon oxide-based antistatic film is used. Since there is a hard surface film between the protective film, the hard surface film acts as a buffer and protects against low temperatures.
No cracks occur even under thermal shock during high-temperature cycles.

(f) Example Example 1 The present invention will be described in detail below with reference to the drawings.

As shown in Fig. 1, magneto-optical recording @ 2
(AIN/DyFeCo/AIN/AI) and a protective film 3 for recording film on it (acrylic urethane UV curing resin)
Deposit a film.

Next, an acrylic urethane UV curable resin is applied on the other surface of the optical disc substrate 1 and cured for 5 to 10 liters.
A hard surface film 4 with a thickness of 0 μm is formed, and Colcoat P (manufactured by Colcoat Co., Ltd.) is applied thereon and cured to form a 0.1 μm thick antistatic film based on noricon oxide. Create.

Example 2 In Example 1, instead of the silicon oxide antistatic film, a coating solution containing tin oxide particles with an average particle size of 0.2 μm mixed in an acrylic urethane UV curing resin was applied and cured to form a film. An optical disc is produced in the same manner as in Example 1 except that an antistatic film with a thickness of 2 μm is formed.

Comparative Example 1 Instead of forming the surface hard film 4 on the other surface of the optical disc substrate 1 and the antistatic film 5 of oxidized noricon type antistatic film 5 on the other surface of the optical disc substrate l in Example 1, the film shown in FIG. 2 was used. An optical disk is produced in the same manner as in Example 1 except that an acrylic urethane UV curable resin mixed with a surfactant is applied and cured to form an antistatic film 6.

The surface hardness (pencil hardness), surface resistivity, and change over time of the optical disks prepared in Examples 1 and 2 and Comparative Example were determined and shown in Table 1.

(Margin below) Table 1

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a previous disc manufactured in an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a conventional optical disc. However, the measurement method is as follows. Pencil hardness: JIS K5400 Surface resistivity: According to JIS K6911. Change over time...High temperature and high humidity retention test (80°C19
Surface observation before and after 0% RH (1240 hours). As a result, it was confirmed that the optical disks obtained in Examples 1 and 2 exhibited excellent performance in terms of surface hardness and surface resistivity, and showed almost no change over time. (G) Effects of the Invention According to the present invention, it has excellent surface hardness and antistatic performance, prevents the adhesion of fine particles in the air, and does not change over time, preventing the laser f- from going off track during operation. It is possible to provide error-free discs. l...Plastic optical disc substrate, 2...
... Magneto-optical recording film, 3... Protective film for recording film,
4...Hard surface film, 5-...Antistatic film.

Claims (1)

[Claims] 1. A hard surface film that allows laser light to pass through and an antistatic film based on silicon oxide or conductive powder mixed resin are laminated in this order on the side of the plastic optical disk substrate intended for laser incidence. An optical disc.