JPS61186384A - Optically recording medium - Google Patents

Abstract

PURPOSE:An optical recording medium that is composed of a recording layer containing a light-absorbing substance and a base layer, thus showing high sensitivity to recording with laser beam, especially semiconductor laser, and high storage stability, as well. CONSTITUTION:A light-absorbing substance of the formula (ring Z<1>-Z<4> are naphthalene or anthracene ring; A is metal or compound containing the same in group IB, IIA, IIB, IIIA of the periodic table) is vacuum metallized on a base plate such as of glass or plastic by resistance-heating under high-vacuum of less than 1X10<-4>Torr to form a film of 1,000-3,000Angstrom , preferably 1,500-2,500Angstrom . Or the compound of the formula is dissolved or dispersed together with a binder such as a polyimide resin in a solvent such as dimethylformamide and the solution is coated by spin-coating to give the objective film.

Description

[Detailed description of the invention] purpose of invention b) Industrial application field TECHNICAL FIELD The present invention relates to an optical recording medium.

(a) Conventional technology Optical recording using a laser has been particularly desired for development in recent years because it enables high-density information recording storage and reproduction.

An example of optical recording is an optical disc.

In general, optical discs are provided on a circular base, and a very thin recording layer is irradiated with a laser beam focused to a diameter of about /μm to record high-density information.

Recording is done by absorbing the irradiated laser energy.
The reproduction of recorded information is generated by thermal deformation such as decomposition, evaporation, and melting of the recording layer at that location.
This is done by using laser light to read the difference in reflectance between areas where deformation has occurred and areas where deformation has not occurred.

Therefore, as a recording medium, it is necessary to efficiently absorb the energy of laser light.

In order to accurately reproduce information, it is necessary to have a high absorption rate for laser light of a specific wavelength used for recording, and a high reflectance for laser light of a specific wavelength used for reproduction.

Until now, such optical recording media have been made of various metals,
Inorganic compounds such as metal compounds and chalcogenides have been proposed, but these thin films are susceptible to air oxidation, difficult to store for long periods of time, and sensitive to ultraviolet and visible light. , sunlight, and other types of light.

As recording bridges using organic compounds, cyanine dyes, squarylium dyes, naphthoquinone dyes, 7-thalocyanine dyes, and the like have been proposed. Among these, cyanine dyes, squalirium dyes, and naphthoquinone dyes generally have poor stability and are difficult to store for long periods of time.
Furthermore, since the reflectance is low, there are drawbacks such as difficulty in reading information.

Some phthalocyanine dyes also have absorption at the wavelength of a semiconductor laser (near If 00 nm), but have the drawback that absorption easily changes with crystal transformation. For example, the absorption near 720 nm in the vapor deposited film of Nazyl phthalocyanine can be reduced by heating to I/j
Changes in nm t (Mo1ec+rlar Cr
ystals and Liqui+i Crysta
ls33, l≠Wata-70 (/ri76)].

C) Objective The object of the present invention is to provide an organic optical recording medium that has high writing sensitivity with laser light, particularly semiconductor laser light, and has good storage stability.

Structure of the Invention The gist of the present invention is an optical recording medium characterized by comprising a substrate and a recording layer containing a light-absorbing substance represented by the following general formula [I].

General formula [1] (7'j'-', in which ring z1 to ring z4 represent a compound containing a metal or a nuclear metal as a substituent belonging to group III) Examples of substituents on the naphthalene ring or anthracene ring of the ring Zl-ring z4 in the optical recording material of the present invention include a methyl group, an ether group, a trifluoromethyl group, a hydroxy group, fluorine, chlorine, and bromine. It will be done.

Examples of metals belonging to Group 1B, Group 1A, Group ■A, Group 1IB, Group 1'l/A, Group 1t/B, Group VB, and Group 1 of A are: CU%Mg%Zn, Sn, P
b, tre, co, N1, and compounds containing these metals include A101, InC1, Ti9.
5nap, etc.

In the optical recording medium of the present invention, it is particularly preferable that ring 21-broken z4 is a naphthalene ring and A is 5 nap.

These compounds are Kotsu 3-dicyanonaphthalene, 2.3
- Easily synthesized from dileananthracene, co, 3-naphthalene dicarboxylic acid anhydride or a derivative thereof and a metal or metal compound, for example, according to a known method of heating 3-dicyanonaphthalene and stannous chloride. can do.

Examples of the substrate material of the present invention include glass and plastics. Plastics are suitable in terms of safety and light weight. Examples of plastics include acrylic resin, methacrylic resin, polycarbonate resin, vinyl chloride resin, vinyl acetate resin, polyester resin, polyethylene resin, polypropylene resin, polyamide resin, polystyrene resin, and epoxy resin.

Methods for forming the recording layer include known methods such as vacuum deposition on the substrate, mixing with a resin solution and coating, and dissolving in a solvent and coating or dipping. Particularly preferred is a vacuum deposition method.

The vacuum deposition method includes heating the compound represented by the general formula (1) by resistance heating or the like in a high vacuum of /x10 Torr or higher, preferably 2X/OTorr or higher, to obtain a vacuum deposited film on the substrate. can be mentioned. The film thickness is 1000 to 3ooo1, especially /! DO~ko! 00A
is preferred.

Film formation by coating can be obtained by spin-coding a compound represented by the above general formula (1) and a binder in a solvent, in which the dissolved material is dispersed. Examples of binders include polyimide resins, polyamide resins, polystyrene resins, acrylic resins, etc., but in particular,
Polyimide resin is preferred.゛In that case, the ratio of light-absorbing substance to wood is / Owt%
The above is desirable.

Various solvents such as dimethylformamide, tetrahydrofuran, dichloromethane, and chlorobenzene can be used, but dimethylformamide is preferred from the viewpoint of solubility.

The recording layer of the optical recording medium of the present invention may be provided on both sides of the substrate or only on one side.

The record on the record body obtained as above is as follows.

This is carried out by irradiating the recording layer provided on both sides or one side of the substrate with a laser beam, preferably a semiconductor laser beam, which is focused to a diameter of about /μm. The area irradiated with the laser light will undergo decomposition, evaporation, and
Thermal deformation of the recording layer, such as melting, occurs.

The recorded information is reproduced by using laser light to read the difference in reflectance between areas where thermal deformation has occurred and areas where thermal deformation has not occurred.

As a light source, various lasers such as a He-No laser, an Ar laser, and a semiconductor laser can be used, but a semiconductor laser is particularly preferable in terms of cost and size.

As the semiconductor laser, lasers having a center wavelength ♂j Onm, a center wavelength 7 r Onm, and shorter wavelengths can be used.

Examples/The light-absorbing substance of the present invention represented by the following formula (III) used in this example was synthesized as follows.

2.3-dicyanonaphthalene (mpco!co213'C
) J, j A f and stannous chloride 1. 02 was dispersed in 1Orrtl of quinoline, stirred for 30 minutes under heating and reflux, and then. After the resulting reaction solution was cooled to room temperature, methanol 1001R1 was added and stirred under reflux for 3 hours. The reaction solution was filtered hot, and the resulting crystals were dispersed in 100 tnl of N-methyl-2-pyrrolidone, stirred at 200°C for 2 hours, cooled to 10O'C, and the crystals were filtered off. Further, a similar treatment with N-methyl-λ-pyrrolidone is performed to obtain a compound represented by the formula [■] (λmax 12 j nm ' in α-chloronaphthalene solvent) /, J
the law of nature? I got it.

The light-absorbing substance of the present invention shown in the following formula
The material was heated to 300°C to 1/-oO°C in a vacuum of 100° C. and then vacuum-deposited onto a methacrylic resin plate with a thickness of 2 m. The film thickness was determined by λoou1 using a quartz crystal film thickness meter. The maximum absorption wavelength of the deposited film is 40 nm, and the peak is broad and clear.

When this vapor deposited film was irradiated with semiconductor laser light with a center wavelength f J Onm at an output of II mW and a beam diameter of about 1 μm, very clear holes (bits) with a width of about 1 μm and a pit size of λ μm were formed. Ta. Carrier level/noise level CC/N) ratio td,! It was 3tlB.

Example! ~II A set of the following formula (IV) [XX] synthesized according to Example/
The light-absorbing material of the present invention shown in Figure 1 was vapor-deposited on a methacrylic resin plate under substantially the same conditions as in Example 1. The film thickness measured by a crystal vibrating film thickness meter was within the range of 000±1ooX.

The maximum absorption wavelength in the α-chloronaphthalene solvent, the maximum absorption wavelength of the thin film, the C/N ratio during semiconductor laser recording, and the storage stability of these light-absorbing substances of the present invention are shown in Table 1 together with the results of Example 1. Shown below. In the table, storage stability is to °C,
The writing performance (C/N ratio) by a semiconductor laser after being stored for 10 days in a 10 qb constant temperature and humidity chamber is shown.

Claims (2)

[Claims] (1) An optical recording body comprising a substrate and a recording layer containing a light-absorbing substance represented by the following general formula [I]. General formula [I] ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・・・・
[I] (In the formula, rings Z^1 to Z^4 represent a naphthalene ring or anthracene ring which may have a substituent, and A represents a group IB group of the periodic table. Group IIA, Group IIB, Group IIIA, Group IIIB, Group IVA, Group IVB, Group VB
Represents a metal belonging to Group VIII and Group VIII or a compound containing the metal) (2) An optical recording medium according to claim 1, in which the light-absorbing substance is represented by the following general formula [II]. General formula [II] ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・・・・
...[II] (In the formula, R_1, R_2, R_3 and R_4 represent a hydrogen atom, an alkyl group, a halogenated alkyl group, a hydroxy group or a halogen atom, and l, m, n, q are 1 to
represents an integer of 6, and A is Sn, SnCl_2,
Pb, Fe, Ni, Co, VO, InCl, TiO, C
u, Mg, Zn or AlCl) (3) The optical recording medium according to claim 1, in which the light absorbing substance is represented by the following general formula [III]. General formula [III] ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・・・・
[III] (wherein A is SnCl_2, Pb, Fe, Ni, Co
, VO, InCl, TiO or Zn)