JPH03113849A - Production of optical recording medium - Google Patents

Abstract

PURPOSE:To eliminate the need for the surface treatment usually applied to improve solvent resistance of a polycarbonate substrate by using an aliphatic hydrocarbon having at least one unsaturated bond as a solvent for a coating soln. to for a recording layer. CONSTITUTION:A recording layer is formed on a polycarbonate resin substrate. In this case, an aliphatic hydrocarbon such as a cyclohexene having at least one unsaturated bond is used as the solvent for a coating soln. to form a record ing layer. Spin coating, etc., are used, the turning rate is changed in accordance with the b.p. of the solvent and the concn. of the coating soln., and a dystuff optimum for writing and reading records is applied and dried. The polycarbonate resin substrate is not attacked by the aliphatic hydrocarbon having at least one unsaturated bond. Consequently, the surface of the polycarbonate resin substrate need not be treated when the solvent is used for the coating soln.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing an optical recording medium on which information can be written and/or read using a high-energy density laser beam. It is.

(Prior art) Optical recording media can dramatically increase the recording density compared to magnetic recording media, and furthermore, information can be written and read without contact, and the recording media will not deteriorate due to wear. Various types of optical recording media are being studied because of their unique characteristics.

Among such optical recording media, heat mode write-once optical recording media have high recording stability and can be manufactured at low cost.

This heat mode write-once optical recording medium is composed of, for example, a recording film layer and a transparent substrate, and during recording, a part of the recording film is melted or removed using a high-power laser beam. , small holes called pits are formed to write and use this information as information, and when reading, low-power laser light is used to detect the bits. Although glass substrates are sometimes used as transparent substrates, polycarbonate substrates are desired for consumer use, as they are lightweight and do not have to worry about breaking due to impact, and are inexpensive to manufacture and highly reliable. . Up until now, most recording film layers have been made mainly of Te, but in order to solve the problem of the toxicity of this material and the high manufacturing costs, in recent years, materials with strong absorption in the wavelength range of semiconductor lasers have been developed. An increasing number of proposals and reports have been made regarding media in which the recording film layer is made of a material mainly composed of an organic dye that can be applied using a spin code or the like. Many cyanine dye-based materials have been reported as organic dyes to be used, but they currently have poor light resistance and low reliability for long-term use. Compared to cyanine dyes, phthalocyanine and naphthalocyanine dyes have better light resistance and are highly reliable in preserving records, but they generally have low solubility in solvents and have soluble groups. Many of the products that have been introduced with this method are only soluble in solvents that may attack the resin substrate, such as halogen-based or ketone-based solvents, so when coating, a photopolymer layer is provided on the surface of the substrate to form groups.
This requires treatment to increase the solvent resistance of the substrate surface. Currently, there is a need for a technology in which phthalocyanine dyes and naphthalocyanine dyes, which have high reliability among organic dyes in preserving records, are applied directly onto inexpensive polycarbonate substrates using a spin cord or the like.

[Structure of the Invention] (Problem to be Solved by the Invention) The present invention is a method of spinning phthalocyanine dyes and naphthalocyanine dyes without requiring surface treatment for improving solvent resistance on a polycarbonate substrate in the production of optical recording media. The purpose is to provide a technology for direct coating with a cord or the like.

(Means for Solving the Invention) The present invention provides an optical recording medium in which a recording layer containing at least one kind of dye selected from phthalocyanine dyes or naphthalocyanine dyes is formed on a polycarbonate resin substrate. A method for producing an optical recording medium, characterized in that a recording layer is formed using an aliphatic hydrocarbon having at least one unsaturated bond as a solvent in a coating solution.

The aliphatic hydrocarbon containing at least one unsaturated bond mentioned above is an aliphatic hydrocarbon of at least one kind selected from the group consisting of alkenes, cycloalkenes, alkynes, cycloalkynes, and those having -OH groups in their skeletons. It is hydrogen. Examples of aliphatic hydrocarbons having at least one unsaturated bond include 1.7-octadiene, cyclohexene, 4-methylcyclohexene, cyclooctene, 1.3-cyclooctene, and 4-vinyl-1-cyclohexene.

3-methyl-1-pentyn-3-ol, 3-methyl-
Examples include 1-butyn-3-ol, but the present invention is not limited thereto.

These may be commercially available or may be synthesized according to conventional methods. These may be used by mixing two or more types of aliphatic hydrocarbons having at least one unsaturated bond, or by mixing other solvents such as alcohol-based saturated hydrocarbons that do not attack the polycarbonate substrate. It may also be used as

These aliphatic hydrocarbons having at least one unsaturated bond do not attack the polycarbonate resin substrate, so when used as a solvent for a coating solution for forming a recording layer, there is no need to perform surface treatment on the substrate. Coating is carried out using a spin cord or the like, and the number of revolutions is varied depending on the boiling point of the solvent and the concentration of the coating liquid, and the dye is coated to a film thickness optimal for recording and reading, and then dried. Drying at 50℃~1
This is carried out at 00°C for about 10 to 60 minutes.

The transparent substrate used in the present invention is preferably a polycarbonate resin substrate, but other resin substrates or glass substrates may also be used.

The phthalocyanine dyes and naphthalocyanine dyes used in the present invention preferably have a soluble group introduced therein to improve their solubility in solvents, and are highly soluble in the wavelength range of the laser beam used during recording and reading. Use dyes with high absorption and/or reflectance.

The technology for coating phthalocyanine dyes and naphthalocyanine dyes according to the present invention is applicable not only to the production of write-once optical recording media conforming to ISO standards, but also to coating dyes as recording films in write-once Kobact discs and reflective films in compact discs. etc.

It can be widely applied when manufacturing optical recording media.

(Examples) Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Example 1 Dye 1 (formula []) was dissolved as a recording dye in cyclohexene to make a 1% by weight solution, and a diameter of 13 cm in groups was prepared.
Coated onto a polycarbonate substrate using a spin coater, and 6
Drying was performed at 0° C. for 30 minutes to form a recording layer with a thickness of 0.06 μm. Coating could be carried out without any problems, and the adhesion between the substrate and the recording layer was also good. When a write/read test was conducted using an optical disk evaluation device using a semiconductor laser with a wavelength of 830 nm, the linear velocity was 4 m/s,
Recording frequency 1000kHz.

A C/N value of 50 dB could be obtained under the conditions of a writing laser power of 7 mW and a reading laser power of 0.8 mW.

First, a grouped polycarbonate substrate with a diameter of 13 cm was used as the resin substrate, and this was immersed in cyclohexene to examine whether or not there was any change in the substrate. After the substrate was immersed in cyclohexene for 5 minutes, the surface of the substrate (substrate) was observed using an optical microscope, and no change in the group shape was observed.

Example 2 Dye 2 (formula [
1] ), a 1% solution by weight was applied to a grouped diameter 13cm+* polycarbonate substrate using a spin coater, and dried at 60°C for 30 minutes to give a solution of 0.07
A recording layer was formed to a thickness of μm. When a write/read test was conducted under the same conditions as in Example 1, a C of 52 dB was obtained.
/N value was obtained.

Example 3 3-methyl-1-butyn-3-ol as solvent.

Dye 3 (formula [I]) was used as a recording dye, and 1% by weight
The solution was applied to a polycarbonate substrate with a diameter of 13 cm in groups using a spin coater, and then heated at 60°C for 30 minutes.
The recording layer was dried for a minute to form a recording layer with a thickness of 0.07 μm. When a write/read test was conducted under the same conditions as in Example 1, a C/N value of 42 dB could be obtained.

First, a polycarbonate substrate with a group diameter of 13 cm was used as the resin substrate, and this was immersed in 3-methyl-1-butyn-3-ol to examine whether or not the substrate changed. Even when the surface of the substrate was observed under an optical microscope after being immersed in 3-methyl-1-butyn-3-ol for 5 minutes, no change in the group shape etc. was observed.

Example 4 Dye 4 (2[
■]) was used as a 1% solution by weight, and was coated onto a polycarbonate substrate with a diameter of 13 cm in groups using a spin coater, and dried at 60°C for 30 minutes to form a 0.07 μm solution.
A recording layer was formed to a thickness of . When a write/read test was conducted using an optical disk evaluation device using a semiconductor laser with a wavelength of 780 nm, the performance was 40 d under the conditions of a linear velocity of 4 m/s, a recording frequency of 1000 kHz, a writing laser power of 7 mW, and a read laser power of 0.8 mW.
The C/N value of B could be obtained.

Formula [11] [Effects of the Invention] The optical recording medium of the present invention includes at least one unsaturated bond such as cyclohexene as a solvent for a coating liquid for forming a recording layer when forming a recording layer on a polycarbonate resin substrate. Since the recording layer is formed using aliphatic hydrocarbons, the solvent does not attack the substrate and there is no need for surface treatment.

Claims (1)

[Claims] 1. A method for producing an optical recording medium in which a recording layer for writing and/or reading information using a laser beam is provided on a polycarbonate resin substrate, which comprises at least one unsaturated bond. 1. A method for producing an optical recording medium, which comprises dissolving a dye using an aliphatic hydrocarbon as a solvent to form a coating liquid, and forming a recording layer by applying the coating liquid onto a substrate and drying it. 2. The aliphatic hydrocarbon containing at least one unsaturated bond is at least one aliphatic carbon selected from the group consisting of alkenes, cycloalkenes, alkynes, cycloalkynes, and those having -OH groups in their skeletons. 2. The method for producing an optical recording medium according to claim 1, wherein hydrogen is used. 3. The method for producing an optical recording medium according to claim 1, wherein the dye is at least one type of dye selected from the group consisting of phthalocyanine dyes and naphthalocyanine dyes.