JPH03203690A - Optical recording medium - Google Patents

Abstract

PURPOSE:To provide an optical recording medium having a recording film having excellent characteristics as to record reproduction or the like without damaging an injection-molded base, by incorporating a specified cyanine coloring matter and a quencher in a recording film of an optical recording medium which comprises the recording film on a plastic base. CONSTITUTION:A recording film on a plastic base of an optical recording medium comprises a cyanine coloring matter of formula I, wherein R1 and R2 are each alkyl of 3 to 6 carbon atoms, and a quencher of formula II, wherein each of R3 to R10 is hydrogen, an alkyl or allyl group, and X is a halogen. The quencher is used for increasing optical stability, particularly for preventing decolorization from being caused by reading light. A solvent used in coating for forming the recording film comprising the quencher and the cyanine coloring matter may be diacetone or the like, which does not damage the base beneath the recording film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical recording medium, and particularly to an optical recording medium having a recording film containing an organic dye.

[Conventional technology]

2. Description of the Related Art Optical recording media generally have a large storage capacity and have excellent features such as being able to be written or read without contact, and have been actively developed.

An example of such an optical recording medium is a write-once optical disc, which focuses a laser beam on a minute area of a recording film and converts it into thermal energy, changing the properties of the recording film. (Pit formation) Recording is performed, and reproduction is performed based on the difference in the amount of reflected light from the unrecorded portion.

The material for the recording film of such a medium is preferably a material that provides a large change in reflectance, and tellurium-based low melting point metal materials were initially used.

However, in recent years, tellurium-based materials have become harmful, and
Because of the need for higher sensitivity and lower manufacturing costs, proposals have been made for optical recording media that use recording films made of organic materials, mainly dyes, instead of tellurium-based materials. (Japanese Unexamined Patent Publication No. 58-112790, No. 58114989, No. 58-1252)
46 Publication, 6C)-71295 Publication, etc.).

An optical recording medium using such a recording film made of an organic material mainly containing a dye generally consists of a substrate and an ultraviolet curable resin layer (2P layer) provided on the substrate to form groups and addresses. , a recording film formed by a spin code method is provided on this ultraviolet curable resin layer.

[Problem to be solved by the invention]

However, the substrate having the 2P layer is made of, for example, Ni
Drop the UV curable resin onto the stamper, place the substrate on top of it, and spread the UV curable resin sufficiently thinly while making sure that no air bubbles remain between the stamper and the substrate.
It is formed by irradiating ultraviolet rays from above the substrate to polymerize and harden the ultraviolet curable resin. Therefore, a problem arises in that the work process becomes extremely complicated and productivity cannot be improved. One possible solution to this problem is to use a so-called injection-molded substrate, in which a plastic substrate with groups and the like is integrally molded by injection molding without using the above-mentioned ultraviolet curable resin.

However, with this injection molded substrate, since the recording film is directly coated on the surface (group side) of the substrate, the problem arises that the substrate is generally damaged by the solvent contained in the coating, making it unsuitable for practical use. Sign.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems and provide an optical recording medium equipped with a recording film that does not damage an injection molded substrate and has excellent recording and reproduction characteristics.

[Means to solve the problem]

In order to solve such problems, the present invention provides an optical recording medium having a recording film on a plastic substrate, in which the recording film is composed of an anine-based dye represented by the following general formula (wherein R1 and R9 are
each represents an alkyl group having 3 to 6 carbon atoms), and a quencher represented by the following general formula (in the formula, R3 to RIO are each represented by
represents hydrogen, an alkyl group, or an allyl group, in which X represents a halogen).

The plastic substrate used in the present invention is a so-called injection molded substrate from the viewpoint of improving productivity. An injection molded board is a board in which a flat board and groups, addresses, etc. provided on one side of the board are integrally formed from the same material by one-shot injection molding.

Such a substrate is made of, for example, polycarbonate resin (PC
), polymethyl methacrylate resin (PMMA), and other plastic materials.

A recording film is formed on such a substrate, and this recording film contains a cyanine dye represented by the following general formula [I].

General Formula [I] General Formula [11] In the above General Formula [I], R and R2 each represent an alkyl group having 3 to 6 carbon atoms. If the number of carbon atoms is less than 3, the solubility in the solvent described below will be lost and film formation will not be possible. If the number of carbon atoms exceeds 6, it also exhibits poor solubility and cannot be formed into a film.

Further, the recording film of the present invention contains a quencher represented by the following general formula [11].

In formula ['II], R3 to RIO each represent hydrogen,
It represents an alkyl group or an allyl group, and in the formula, X represents a halogen.

Such an encher is used to increase photostability and, in particular, to prevent decolorization (reproduction deterioration) caused by readout light.

The recording film containing the encher and the cyanine dye is coated by a conventional method such as a spin-coating method. The thickness of the recording film coated is 40 to 110
It is about 0n. Note that examples of the solvent used for coating include diacetone alcohol, ethyl cellosolve, methyl cellosolve, isophorone, methanol, and the like. These solvents are suitable because they do not damage the substrate on which the recording film is provided.

The laser beam applied to the recording medium of the present invention is appropriately selected depending on the absorption wavelength of the dye used, and among them, a semiconductor laser (wavelength: 760 to 830 nm) is preferable.

As mentioned above, the recording medium of the present invention is formed by providing a recording film on a so-called injection molded substrate, but usually two of these are prepared and the recording film is placed facing each other. A sandwich structure is preferred.

[Effect]

The medium of the present invention is generally irradiated with recording light in a pulsed manner while being rotated.

At this time, part of the recording film is melted and removed to form pits.

The pits formed in this way are also caused by the rotation of the medium.
This is done by detecting the difference in the reflected light of the read light.

〔Example〕

Hereinafter, the present invention will be explained in further detail by showing examples of the present invention.

The dyes contained in the recording film include the following [D
-1] to [D-5], and as a quencher, use [Q-1] or [Q*] shown below, dissolve them in the solvent shown in Table 1 below, and Various optical recording medium samples were prepared by coating a polycarbonate (PC) substrate to a thickness of 60 nm.

Dye [D-1] In the above general formula [1], R and R2 are each represented by ICs Hz (isopentyl group).

[D-2] In the above general formula [1], R and R2 are each C
2Hs (ethyl group).

[D-3] In the above general formula [I], R and R2 are each C-r H15 (heptyl group).

[D-4] In the above general formula [I], R1 and R2 each represent C
It was set as H3 (methyl group).

[I)-5] The recording film configuration of the optical recording medium sample prepared by the above method and the evaluation results thereof are shown in Table 1 below.

The evaluation items include the solubility of dyes and quenchers, fluctuations in system control signal levels and changes in recording and reproducing characteristics under high temperature and high humidity environments (70°C, 90% RH), and characteristics of the number of times of repeated readout. was evaluated. Furthermore, the comprehensive characteristics of these properties were also evaluated.

The results are shown in Table 1 below. (Left below) Quencher [Q-1] Trade name IRGO23 (manufactured by Nippon Kayaku Co., Ltd.) represented by the general formula [n].

[Q*] N” (n-C4H914 For sample seed 8, the substrate material was changed to sample N
a Instead of injection molded substrates 1 to 7, so-called PMMA
A substrate was obtained by combining the above and an ultraviolet curable resin layer (2P layer).

〔Effect of the invention〕

From the above results, the effects of the present invention are clear.

That is, since the optical recording medium of the present invention contains a specific cyanine-based dye and quencher in the recording film, it can be coated directly onto a so-called injection molded substrate without damaging it, and can be coated directly onto a substrate without damaging the so-called injection molded substrate. UV-curable resin layer (
Productivity is significantly improved compared to a medium using a substrate having 2P#).

Furthermore, the recording and reproduction characteristics are also extremely excellent.

Evaluation criteria ◎ Very good, O...Good, △ Somewhat problematic at practical level, X Outside practical level

Claims (1)

[Scope of Claims] In an optical recording medium having a recording film on a plastic substrate, the recording film contains cyanine dyes (in the formula R_1 and R_2
each represents an alkyl group having 3 to 6 carbon atoms), and
Contains a quencher represented by the following general formula ▲ Numerical formulas, chemical formulas, tables etc. Characteristic optical recording media.