JPH0549473B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical recording medium on which information can be recorded and reproduced using laser light, and more particularly to an optical recording medium using an organic dye.

(Prior art and its problems) Conventionally, as this type of optical recording medium, Te alloy,
Te oxide and organic dyes are used. Organic dyes generally have excellent properties in that highly sensitive and non-polluting media can be produced at low cost, and various attempts have been made to develop media. They can be roughly divided into vapor deposition type and solvent coating type. In the solvent coating type, for example, as disclosed in JP-A-55-161690, polyvinyl acetate, which is a polymeric resin, is mixed with polyester yellow as a dye using a solvent, and is formed on a substrate by a spin coating method. Therefore, when using resin for the substrate, there is a restriction that a solvent must be selected that does not dissolve the resin. On the other hand, a medium formed by vapor deposition is a practically desirable medium because it does not impose restrictions on the selection of a substrate. However, vapor-deposited dye films generally exhibit deterioration in surface properties due to association (aggregation). This deterioration determines the lifespan of the medium, so in the case of evaporation type media,
Although it is important to use a medium with low association,
Until now, no medium with sufficient longevity has been developed.

(Objective of the Invention) An object of the present invention is to improve the drawbacks of the prior art described above and to provide an optical recording medium having a recording layer containing an organic dye as a main component and having excellent long-term storage stability.

(Structure of the Invention) The present invention provides an optical recording medium in which a recording layer is provided on one or both sides of a substrate, and information is recorded and read by a laser beam. -dicyano-1,4-naphthoquinone dye or 5,8-(substituted anilino)-
It is characterized in that the recording layer is a layer containing a mixture of 2,3-dicyano-1,4-naphthoquinone dye or a metal complex thereof and a porphine type compound.

(Detailed Description of Configuration) The present invention solves the problems of the prior art by adopting the above-described configuration.

5-amino-8-(substituted anilino)-2,3-dicyano-1,4-naphthoquinone dye or 5,8
-(substituted anilino)-2,3-dicyano-1,4-
By selecting an alkyl group, an alkoxyl group, an allyl group, an amino group, or a substituted amino group as a substituent for the substituted anilino of naphthoquinone dyes or metal complexes thereof, the film formability by vapor deposition and the associativity of the vapor deposited film can be improved compared to that of unsubstituted anilino. ( ) better than The alkyl group and alkoxyl group of the substituent preferably have 1 to 4 carbon atoms, and more preferably an alkoxyl group.

These naphthoquinone dyes and their metal complexes exhibit maximum absorption in the near-infrared region, and when a semiconductor laser is used as a recording/reproducing laser, it is expected that the oscillation wavelength will match well with that of a semiconductor laser and a highly sensitive medium can be formed.

Synthesis examples of the naphthoquinone dye and its metal complex are shown below.

First, known 2,3-dichloro-1,4-naphthoquinone was nitrated with nitric acid and sulfuric acid to produce 5-nitro-
2,3-dichloro-1,4-naphthoquinone is obtained. Next, cyanation is performed with sodium cyanide to obtain 5-nitro-2,3-dicyano-1,4-dihydroxynaphthalene. Subsequently, after reduction treatment with stannous chloride and hydrochloric acid, oxidation treatment with ferric chloride was performed to obtain 5-
Amino-2,3-dicyano-1,4-naphthoquinone [ ] is obtained. [] Thoroughly crush 1 g, disperse in 400 ml of ethanol, and reflux. p to this
- A solution of 1.23 g (2 molar ratio) of ethoxyaniline in ethanol (10 ml) is added dropwise and stirred for 10 minutes under reducing conditions. After the reaction was heated, the solution was cooled with water, the resulting precipitate was filtered, dried, and recrystallized from chloroform to obtain 380 mg (yield 24%) of the purified product (mp254-256
°C) is obtained.

The identification results of this purified product are: (1) λmax 760nm (in acetonitrile) (2) Mass spectrometry (M/e) 358, 330, 329 (3) Elemental analysis values Calculated values C: 67.03% N: 15.64% H: 3.94
% Experimental value C: 67.09% N: 15.85% H: 3.85
%, which is 5-amino-8-(p-ethoxyanilino)-2,3-dicyano-1,4-
It was confirmed to be naphthoquinone. Next, dissolve 200mg of [] in 300ml of acetonitrile,
A solution of 72 mg (1 molar ratio) of cobalt chloride dissolved in 50 ml of acetonitrile is added to this, and the mixture is refluxed for 3 hours at the boiling point of acetonitrile. After that, it was distilled under reduced pressure and the residue was washed with acetonitrile.
When washed, washed with water, and dried, 5
-amino-8-(p-ethoxyanilino)-2,3
130 mg of a purified cobalt complex of -dicyano-1,4-naphthoquinone dye was obtained.

When this purified product was analyzed by silica gel thin layer chromatography using acetonitrile as a developing agent, no complex was developed. Note that the R _f value of [] is 0.9.

Other naphthoquinone dyes and metal complexes thereof can also be synthesized in the same manner as in the above synthesis example.

The stabilizing materials used in the present invention include B,
Al, Mg, Si, Ca, Sc, Ti, V, Cr, Mn, Fe,
Co, NiCu, Zn, Ga, Ge, Sm, Sr, Y, Zr,
Nb, Tc, Ru, Rh, Pd, Ag, In, Sn, Ba,
La, Hf, Ta, Re, Ir, Pb, BiDy, Er, Gd,
Nitride, fluoride, oxide of elements such as Nd and Pr,
Selected from carbides and various organic materials. Particularly desirable are GeO ₂ , SiO, SiO ₂ , Al ₂ O ₃ , Cr ₂ O ₃ Y ₂ O ₃ ,
La ₂ O ₃ , CeO ₂ , Sm ₂ O ₃ , ZnO, TiO ₂ ,
MgF ₂ CaF ₂ , porphin type compounds, etc. In particular, metal-free phthalocyanines and central atoms (molecules) are more desirable among porphyne type compounds.
Li, Na, Mg, Al, K, Ca, Ti, TiO, V,
VO, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga,
Ge, Y, Mo, Rh, Pd, Ag, In, Sn, Ba, La,
Ce, Pr, Nd, Sm, Eu, Gd, Dy, Tb, ErYb,
These are phthalocyanine compounds such as Hf, Os, Pt, and Pb, or fluorine-substituted products and chlorine-substituted products thereof.

The mixing ratio of the naphthoquinone dye or its metal complex and the stabilizing material is such that the amount of the stabilizing material mixed is 1
It is desirable to select a range of ~50vol%.

The most common method of making mixed layers is codeposition. This is a method in which the naphthoquinone dye or its metal complex and the stabilizing material are simultaneously evaporated from separate evaporation sources to obtain a mixed layer on a substrate held above the evaporation source. Or 50
A pseudo-mixed layer may be formed by alternately stacking thin films of Å or less. As a heating method for the evaporation source, resistance heating, electron beam heating, etc. can be used. Further, sputtering, ion beam deposition, cluster ion beam deposition, ion plating, etc. can be used, and the naphthoquinone dye or its metal complex and the stabilizing material may be formed by separate deposition methods.

Although various substrates can be used to support the recording layer, glass, aluminum alloy, and synthetic resin are generally preferred. Examples of synthetic resins include polymethyl methacrylate (PMMA), polycarbonate, epoxy, polyetherimide, polysulfone, and polyvinyl chloride. The substrate shape can be a disk shape, a table shape, or a sheet shape.

When a semiconductor laser beam is focused by a lens and irradiated onto a recording layer formed on a substrate, the recording layer in the irradiated area is removed and a hole is formed. Although the mechanism of this pore formation is not clear, it is thought to be due to melting and aggregation accompanied by evaporation (sublimation). The size of the hole formed depends on the focused diameter of the laser beam, laser power, and irradiation time, but it is preferably about 0.2 to 3 μm. The laser energy required to form such a hole is small, and therefore the hole can be formed in a short time. Specifically, the wavelength is 830nm.
When AlGaAs semiconductor laser light is focused to a beam diameter of 1.4 μm, holes can be formed in the recording layer with a power of 2 to 13 mW and an irradiation time of 50 to 300 nsec. Naturally, holes can be formed under conditions that exceed the upper limits of the power or irradiation time, but the above conditions are desirable usage conditions. Information is recorded by associating binary information with the presence or absence of holes. Information is usually recorded by rotating a disk-shaped medium at a constant speed and forming holes in accordance with the recorded information. In the above case, the thickness of the recording layer is 0.01 to 0.5 μm, preferably 0.02 to 0.2 μm.
It is. The information (holes) recorded in this manner is read out by detecting changes in the amount of light reflected or transmitted from the medium. Generally, a method of detecting reflected light is adopted. This is because the optical system for reflected light detection is simpler. That is, this is because one optical system can project and collect light. For reading, laser light is continuously irradiated.
The amount of light at this time is set to a weak energy that does not cause any shape change to the medium, and is 1/5 to 1/10 of the amount of light during normal recording.

There are two directions of incidence of light during recording and reproduction: toward the medium surface and toward the substrate surface. Both orientations can be used with single layer media such as the present example. When the light is incident on the substrate surface side, recording and reproduction are possible without being affected by dust attached to the medium surface, which is a more desirable form. Note that if the substrate thickness is 1 mm or more, the beam diameter on that surface is sufficiently large to prevent dust adhering to the surface of the substrate opposite to the surface on which the medium is formed, as well as defects such as scratches on that surface. It has little negative effect on recording and playback.

Information is recorded as a series of holes. The rows of holes generally form a number of concentric or spiral tracks. When reproducing, the light beam needs to accurately track the hole rows of a specific track. One way to achieve this is to increase the precision of the rotation mechanism by using air bearings or the like. However, in this case, the rotation system becomes complicated and expensive, so it is not practical. More desirable is
This is a method of providing light guide grooves on a substrate. When light enters a groove about the diameter of a beam, it is diffracted.
The spatial distribution of the diffracted light intensity changes as the beam center shifts from the groove, and a servo system can be configured to detect this and direct the beam to the center of the groove. Usually, the width of the groove is set in the range of 0.4 to 1.2 μm, and the depth is set in the range of 1/8 to 1/4 of the recording/reproducing wavelength used. The recording layer is therefore formed on the grooved substrate surface.

Embodiments of the present invention will be described in detail below with reference to the drawings.

Example 1 In a vapor deposition apparatus having two resistance heating boats, 5-amino-8-(p-ethoxyanilino)-2,3-dicyano-1,4-naphthoquinone dye was placed in the other boat and A vanadium oxide phthalocyanine dye was placed in the boat, and both boats were heated independently to deposit the naphthoquinone dye and the phthalocyanine dye on the substrate together. Diameter as substrate
An acrylic plate of 120 mm and 1.2 mm thickness was used and rotated at 10 rpm. The figure shows a cross section of the medium thus obtained. A mixed layer 20 is provided on the acrylic substrate 10 as a recording layer. The thickness of this mixed layer is 810 Å, and the mixing ratio of the naphthoquinone dye and the phthalocyanine dye is approximately 10:1 in terms of the monolayer thickness ratio. When the optical properties of this medium are measured at a wavelength of 830 nm, when it is incident on the substrate,
The reflectance was 18% and the absorption was 54%. wavelength
Semiconductor laser light of 830 nm was focused by an optical system (not shown) and irradiated onto the medium from the direction of arrow 30. When recording was performed under the conditions of a laser beam power of 10 mW on the medium surface, a recording frequency of 2.5 MHz, and a linear velocity of 13 m/sec, holes (pits) 40 were formed in the mixed layer 20. Such recording was similarly possible even when light was incident from the front side of the medium, that is, from the direction of arrow 50. When the recorded pits were played back with 0.9mW continuous light, a C/N of 53dB was obtained. The long-term storage stability of the medium was evaluated by the following method. The mixed layer was observed under a 1000x optical microscope, and the presence or absence of aggregate particles generated on the surface of the film was used as a criterion for determining deterioration. An accelerated test was performed, and the mixed layer was compared with the case of only the naphthoquinone dye, showing that the mixed layer deteriorated more. It was difficult. Comparing the lifespan, when using only the naphthoquinone dye,
It was confirmed that the mixed layer according to the present invention had a lifespan of about 20 years or more, compared to about 10 years.

(Example 2) In the same manner as in Example 1, 5-amino-8-(p
-ethoxyanilino)-2,3-dicyano-1,
A mixed layer of 4-naphthoquinone dye and _MgF2 was prepared. The film thickness is 900 Å, and the mixing ratio is approximately 10:1. When recorded and reproduced in the same manner as in Example 1, a C/N of 49 dB was obtained, and the storage stability was also good. Furthermore, the same lifespan as in Example 1 was confirmed.

Example 3 In the same manner as in Example 1, 5-amino-8-(p
-methoxyanilino)-2,3-dicyano-1,
A mixed layer of a cobalt complex of 4-naphthoquinone dye and a copper phthalocyanine dye was prepared. Film thickness is 860
Å, the mixing ratio is approximately 8:1. When recorded and played back in the same manner as Example 1, the C/N was 52 dB.
was obtained and had good storage stability. Next, Example 1
When the lifespan was investigated using the same method as above, it was found that the naphthoquinone dye complex alone had a lifespan of about 25 years, but in the case of the present invention, a lifespan of more than 30 years was predicted.

(Effects of the Invention) As is clear from the above examples, the present invention provides an optical recording medium that is stable and has good recording characteristics.

[Brief explanation of the drawing]

The figure is a schematic diagram showing an embodiment of the optical recording medium according to the present invention, and in the figure, 10 is a substrate, 20
is a mixed layer, 30 and 50 are light incident directions, and 40 is a hole.

Claims (1)

[Claims] 1. In an optical recording medium in which a recording layer is provided on one or both ends of a substrate and information is recorded and read by a laser beam, 5-amino-8-(substituted anilino)-2,3-dicyano-1,4-naphthoquinone Optical recording characterized in that the recording layer is a layer containing a mixture of a dye, a 5,8-(substituted anilino)-2,3-dicyano-1,4-naphthoquinone dye, or a metal complex thereof, and a porphine type compound. Medium.