JPH0489279A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To collimate a condensed light beam and make it possible to apply the beam to an optical pickup using laser capable of high-density data recording by providing a recording layer containing a carotene compound as a main component on a substrate. CONSTITUTION:A carotene compound has a long-chained carbon/carbon bond and has a specific chemical structure consisting of a single bond and a double bond interwoven alternately. In addition, the compound shows a light absorptive activity of 10<5> or higher of molecular absorption factor in the neighborhood of wavelengths of 400 to 550nm, so that a recording film has a high light absorption and a high reflection factor in the neighborhood of wavelengths of 400 to 550nm and also most appropriate properties over a reflection-type optical disk. An optical information recording medium basically has a recording layer 2 containing the mentioned color on a substrate 1. The recording layer can be formed using evaporation, CVD or solvent application technique. Further, an undercoat layer 3, a protecting layer and a reflection layer 5 can be added.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical information recording medium, such as an optical disk or an optical card, on which information can be recorded and reproduced using a focused laser beam, and which is suitable for computer memory. , which can be applied to a memory device for image files.

[Prior Art] Practical organic recording materials for semiconductor lasers with an optical wavelength of 750 nm to 850 nm are known. Typical examples are those in which a thin film of polymethine dyes such as cyanine dyes, phthalocyanine dyes, naphthoquinone dyes, naphthalocyanine dyes, squalirium dyes, etc. is provided on a substrate.

However, these dyes have wavelengths of 400ni to 550n11.
Since it has no light absorption or light reflection properties in the short wavelength range of , there is a limit to its high-density recording performance.

[Problem to be solved by the invention] The shorter the wavelength of the focused beam, the more narrowly the focused beam can be focused.

Therefore, the present invention aims to provide a recording medium that can be applied to optical pickup using a laser with a wavelength of 400 nm to 550 nm, which enables high-density recording by narrowing down the condensed beam.

[Means for Solving the Problems] A configuration of the present invention for solving the above problems is an optical information recording medium having a recording layer containing a carotene compound as a main component on a substrate.

The carotene compound used in the recording layer in the present invention is T
HE MERK INDEX, 9T) I EDITI
ON Specific examples are given using compound numbers and names. 1
852. α-Carotene, 1853. β-Ca
rotene (the structural formula is shown below), 1854.
r-Carotenex 1855. δ-Caro
ten, 875. Astacin, 877, A
staxanthin.

8049. Rubixanthine, 9726. Xan
Examples include thophyl, 9776° Zeaxanthin.

β-carotene All of these compounds have long chains of carbon-carbon bonds, and have a unique chemical structure in which double bonds and double bonds are alternately repeated.
It exhibits strong light absorption ability with a molecular extinction coefficient of 105 or more around m. Therefore, the recording film of the present invention has a wavelength of 400t+o~5.
It exhibits strong light absorption near 50 nm and high reflectance, and exhibits characteristics suitable for reflective optical discs.

Further, similar compounds having a carbon-carbon bond and a long chain structure in which - double bonds and double bonds are alternately repeated may also be used.

These compounds include those with partially changed substituents,
Includes those in which the length of the long chain portion has changed somewhat. Carotene compounds also exhibit the action of vitamin A, so they are non-toxic and good for health, so there is no harm caused by mass production.
, highly practical.

The optical information recording medium of the present invention basically consists of a substrate and a recording layer, but if necessary, an undercoat layer, a protective layer, a reflective layer, etc. can be further provided. It is also possible to form a so-called air sandwich structure in which two recording media are placed facing each other with their recording layers facing each other.

The recording layer in the present invention is capable of causing some optical change by irradiation with laser light and recording information based on the change, and it is necessary that the recording layer contains the dye of the present invention. Furthermore, in forming the recording layer, the dyes of the present invention may be used alone or in combination of two or more. Furthermore, the above-mentioned dyes of the present invention can be used with other dyes such as phthalocyanine dyes, tetrahydrocholine dyes, dioxazine dyes, triphetchazizine dyes, phenanthrene dyes, cyanine (merocyanine) dyes, naphthoquinone dyes, anthraquinone dyes, and anthraquinone dyes. xanthine dyes, triphenylmethane dyes other than the above-mentioned dyes of the present invention, croconium dyes, pyrylium dyes, azulene dyes, metals, metal compounds such as In, Sn, Te, B15A, 77, Se, T
It can also be used in the form of a mixed dispersion or lamination with aO2, SnO, As5Cd, etc. Further, the above-mentioned dye of the present invention can be mixed and dispersed in various materials such as polymeric materials such as ionomer resins, polyamide resins, vinyl resins, natural polymeric substances, silicones, and liquid rubbers, or silane coupling agents. They may be used together with stabilizers (eg, transition metal complexes), dispersants, flame retardants, lubricants, antistatic agents, surfactants, plasticizers, etc. for the purpose of improving properties.

Next, the structure of the optical information recording medium according to the present invention will be explained with reference to the drawings.

As shown in FIG. 1, the optical information recording medium of the present invention basically comprises a substrate 1 and a recording layer 2 containing the dye of the present invention. Further, the recording layer can also have a two-layer structure in which a light-reflecting layer and a light-absorbing layer are combined in any order.

The recording layer can be formed by conventional means such as vapor deposition, sputtering, CVD or solution coating. When a coating method is used, the dye of the present invention is dissolved in an organic solvent, and the coating is carried out by a conventional coating method such as spray roller coating, dipping, and spinning.

Organic solvents generally include alcohols such as methanol, ethanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, and NN.
-Amides such as dimethylformamide and N,N-dimethylacetamide, sulfoxides such as dimethylsulfoxide, ethers such as tetrahydrofuran, dioxane, and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, chloroform,
Aliphatic 10-genated hydrocarbons such as methylene chloride, dichloroethane, carbon tetrachloride, and trichloroethane, or aromatics such as benzene, toluene, xylene, ligroin, monochlorobenzene, and dichlorobenzene can be used.

The appropriate thickness of the recording layer is 100 μm to 10 μm, preferably 200 μm to 1,000 μm. Further, it is desirable for the recording layer to have a reflectance of at least 15% from the substrate side for recording and reproduction.

The substrate 1 must be transparent to the laser beam used when recording and reproducing is performed from the substrate side, and does not need to be transparent when recording and reproducing is performed from the recording layer side. As the substrate, glass, plastics such as polyester, polyamide, polyolefin, polycarbonate, epoxy, polyimide, and polymethyl methacrylate, metals, and ceramics are usually used, but any other materials used for recording media may be used.

Further, as shown in FIGS. 2 to 6, an undercoat layer 3 and/or a protective layer 4 and/or
Alternatively, a configuration in which a reflective layer 5 is provided may also be used. At this time, the subbing layer and/or the protective layer may contain a dye represented by the above formula of the present invention.

The undercoat layer 3 (a) improves adhesion, (b) serves as a barrier against water or gas, (C) improves storage stability of the recording layer, and (d)
) improvement of reflectance, (e) protection of the substrate from solvents and (
f) Used for purposes such as forming pre-grooves.

For the purpose of (a), various substances such as the above-mentioned polymer materials and silane coupling agents can be used;
For the purposes of b) and (c), inorganic compounds such as S io2, MgF2, S io, Ti are used in addition to the above polymer materials.
O2, ZnO.

Metals or metalloids such as TiN, SiN, etc. Zn, C
u5S, Ni, Cr, Ge5Se, Cd.

For the purpose of (d), metals such as Ag, Ag, etc. or organic thin films with metallic luster such as methine dyes, xanthine dyes, etc. can be used, and (e) , for the purpose of (f), ultraviolet curing resins, thermosetting resins, thermoplastic resins, etc. can be used.The film thickness of the undercoat layer is 0.01.
~30μm, preferably 0.05~10μm or appropriate. The protective layer 4 is provided for the purpose of protecting the recording layer from scratches, dust, dirt, etc. and improving the chemical stability of the recording layer, and the same material as the undercoat layer can be used for the protective layer 4. The thickness of the protective layer is suitably 0.1 μm or more, preferably 50 μm or more.

Furthermore, as another configuration of the optical information recording medium according to the present invention, two recording media having the same configuration as shown in FIGS. It may be arranged in a so-called air sandwich structure in which it is placed inside and sealed, or it may be in a so-called close-contact sandwich structure (bonded structure) in which it is adhered with the protective layer 4 interposed therebetween.

Information is recorded by focusing laser light with a lens to form minute holes (pits) on the recording layer, and reading is performed by irradiating weak laser light and detecting the difference in reflectance between the pit and other parts. This can be done using .

Note that if a second harmonic of a semiconductor laser having a wavelength of 750 to 850 r+m is used as the laser light source, the device can be made smaller.

[Example code] The present invention will be specifically explained below based on the implementation side.

Example 1 β-carotene was dissolved in toluene and applied to an acrylic substrate with a spinner to a thickness of 500 mm. The thin film thus formed had a reflectance of 30% and an absorption rate of 30% at a wavelength of 488r+m. When recording was performed on this recording medium using an argon laser with a wavelength of 488 r+m, it was possible to record pits with a diameter of 0.5 μm, and it was also possible to reproduce information by detecting reflected light.

Example 2 The same experiment as in Example 1 was conducted except that γ-carotene was used, and the same results were obtained.

[Effects of the Invention] As explained above, the optical information recording medium of the present invention enables higher density recording than conventional recording media.

[Brief explanation of the drawing]

1 to 6 are schematic cross-sectional views showing specific structural examples of the optical information recording medium of the present invention. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Recording layer, 3...Undercoat layer, 4
...protective layer, 5...reflection layer.

Claims (1)

[Claims] An optical information recording medium comprising a recording layer containing a carotene compound as a main component on a substrate.