JPH03215466A - Near-infrared light absorber, its intermediate and optical recording medium using the same - Google Patents

Abstract

NEW MATERIAL:A phthalonitrile of formula I (R is unsubstituted or substituted alkyl). EXAMPLE:A compound of formula II. USE:Useful as an intermediate for near-infrared light absorbers to be used in the recording layers of existing optical recording media compatible and commonly usable with and additionally recordable on CD players. PREPARATION:3-Nitrophthalonitrile and an alcohol are heated and agitated at 50-120 deg.C in an aprotic polar solvent (e.g. dimethylformamide, dimethylsulfoxide) in the presence of a catalyst (e.g. sodium hydroxide, 1,4- diazabicyclo(2,2,2)-octane), and the system is fed into water followed by extraction, recrystallization, etc., with an organic solvent such as toluene, thus obtaining the objective compound of the formula I. And, this compound and a metal derivative are heated and agitated in a high boiling solvent in the presence of a catalyst, and the system is fed into water followed by extraction with an organic solvent, thus obtaining the other objective phthalocyanine near- infrared light absorber of formula III.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to near-infrared absorbers that play an important role in the field of electronics such as optical recording and display sensors, intermediates thereof, and commercially available compact discs. It relates to an optical recording medium that is compatible with a drive, that is, a CD player, and on which additional data can be written.
Various information such as code data can be recorded on an optical recording medium, and the recorded information can be read by a commercially available CD or CD-ROM player. [Prior Art] CDs or CD-ROMs are widely used as large-capacity, high-speed access digital recording media for storing and reproducing audio, images, code data, and the like. However, once recorded, all of these are playback-only and cannot be updated. Like magnetic tape, it is a so-called write-once type that allows users to record only the desired information, update records, and edit it, and is also compatible with CD or CD-ROM players. An optical recording medium with the following characteristics is desired. Write-once optical recording media with recording layers made of tellurium, inorganic thin films, or organic dyes such as near-infrared absorber cyanine have already been developed and are available on the market, but these write-once optical recording media have low reflectance. It is difficult to detect and reproduce recorded information using existing CD drives. A medium with a recording layer made of indium germanium and capable of recording with high reflectivity has been developed, but since it does not fully satisfy the CD standards, it can only be played by some CD players. Moreover, this medium lacks credibility. On the other hand, high-reflectance media with a metal reflective film on the recording layer have been proposed. For example, a reflective layer of metal such as gold is provided on a monolayer film of a mixture of organic dyes.
Recordable media that is compatible with D players has been developed. ("Optical Data Sto
rageTechnical
ies-1, 45, 1989) However, this medium has disadvantages in that waveform distortion occurs when signals are recorded, resulting in many errors and poor durability, particularly light resistance.

On the other hand, JP-A-62-146683 discloses an optical recording medium using β-alkoxy-substituted phthalocyanine. However, what is disclosed above relates to a medium in which a metal reflective layer is not provided, and as in the present invention, a β-alkoxy substituted lid is added to a medium in which a metal reflective layer is provided on a recording layer. When cyanine is used and recording is performed with the same bit length as a CD, the waveform distortion becomes extremely large and errors occur frequently, resulting in a lack of reliability and impractical use. [Problem to be solved by the invention] As described above, existing optical recording media that are compatible with CD players, can be shared, and are recordable have various drawbacks, but these drawbacks have been solved. The development of optical recording media is desperately needed. The purpose of this invention is to provide an improved optical recording medium in which the above-mentioned drawbacks are eliminated, and for this purpose, to provide a new near-infrared absorber for use in the recording layer of the optical recording medium. be.

[Means for Solving the Problems] The inventors aimed to solve the above-mentioned drawbacks of existing optical recording media by creating a disc that is compatible with CD players and that allows additional recording. As a result of various research and studies to provide an optical recording medium, we developed a new near-infrared absorber and completed this invention by using the following dye in the recording layer. That is, this invention is based on the formula (2), [In formula (2), R, R, and R each independently represent an unsubstituted or substituted alkyl group, and M represents two hydrogen atoms or a divalent alkyl group. Indicates metal atoms, monosubstituted trivalent metal atoms, disubstituted metal atoms, and oxymetal atoms. ] A phthalocyanine near-infrared absorber represented by the general formula (2
) is an intermediate compound represented by the following general formula (1) for the production of a compound represented by [(1), R represents an unsubstituted or substituted alkyl group]. ], and a write-once optical recording medium compatible with compact disk drives, having a reflectance of readout laser light through the substrate of 60% or more, comprising: a transparent injection molded resin substrate; The present invention is an optical recording medium, which is substantially composed of a recording layer having a 100% carbon content and a metal reflective layer, and containing a near-infrared absorber represented by the above formula (2) in the recording layer.

Specific examples of unsubstituted or substituted alkyl groups represented by R1, R2, R3, and R4 in the phthalocyanine dye represented by general formula (2) of this invention, and R in its intermediate represented by general formula (1) For example,
Methyl group, ethyl group, n-probyl group, n-butyl group,
lowbentyl group, n-hexyl group, n-hebutyl group, n
- Primary alkyl groups such as octyl group, n-nonyl group, n-decyl group, n-dodecyl group, isobrobyl group, sec
-butyl group, isobutyl group, l-ethylbrobyl group, 1
-Methylbutyl group, neobentyl group, isoamyl group, 2
-Methylbutyl group, 1,2-dimethylbutyl group, 1-
Methylhebutyl group, l-ethylbutyl group, 1,3-dimethylbutyl group, 1,2-dimethylbutyl group, 1-ethyl-2-methylbrobyl group, 2-ethylbutyl group, 2-methylpentyl group, 3-methylpentyl group , 4-methylbentyl group, 2-methylhexyl group, 3-methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, 2
-Ethylpentyl group, 3-ethylbentyl group, l-methylhexyl group, 2-methylhebutyl group, 3-methylhebutyl group, 4-methylhebutyl group, 5-methylhebutyl group, l-propylbutyl group , ■-isobrobyl-2-methylbrobyl group, l-ethyl-2-methylbutyl group, ■-
Ethyl-2-methylbutyl group, l-propyl-2-methylbrobyl group, 2-ethylhexyl group, 3-ethylhexyl group, l-ethylhexyl group, l-probylbentyl group, ■-isobrobylbentyl group, l-isobrobyl group −
2-methylbutyl group, l-isobutyl-3-methylbutyl group, l-methylheptyl group, l-ethylheptyl group, l-methylbutyl group, l-propylhexyl group, 1
-isobutyl-3-methylbutyl group, 4-methylcyclohexyl group, 4-ethylcyclohexyl group, 4-ter
Examples include secondary alkyl groups such as t-butylcyclohexyl group, 4-(2-ethylhexyl)cyclohexyl group, bornyl group, and isobornyl group.

Furthermore, these primary and secondary alkyl groups may be substituted with a hydroxyl group or a halogen, or may be substituted with the above alkyl group or aryl group via an atom such as oxygen, sulfur, or nitrogen. You can. Examples of the alkyl group that must be substituted via oxygen include methoxymethyl group, methoxyethyl group, ethoxymethyl group, ethoxyethyl group, butoxyethyl group, ethoxyethoxyethyl group, phenoxyethyl group, methoxybutyl group, ethoxybutyl group Examples of alkyl groups substituted with a sulfur group include methylthioethyl group, ethylthioethyl group, ethylthiobrobyl group, phenylthiobrobyl group, etc., and examples of alkyl groups substituted with a nitrogen group include dimethylaminoethyl group, diethylaminoethyl group,
Examples include jethylaminoprobyl group. Specific examples of M in general formula (2) include Ca, Mg,
Zn, Cu, Ni%Pd, Fe. Pb. Co
．． Divalent metals such as Pt%Cd, Ru, AI. I
n. Fe. Ga. T.I. Octalides, hydroxylates, alkoxides, trialkylsiloxy groups, etc. of trivalent metals such as Mn, as well as Si, Ti, S
n, Cr, Ge, Sn. Examples include tetravalent metal halides, alkoxides, hydroxylations, trialkylsiloxides, and oxides of tetravalent metals such as Mn and Zr%V. The phthalonitrile compound of general formula (1) can be produced by the following method. 3-nitrophthalonitrile and alcohol in an aprotic polar solvent, e.g. dimethylformamide (1)MF)
．． In dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), etc., as a catalyst, for example, sodium hydride, 1,4-diazabicyclo(2
, 2, 2) One octane, l, 5-diazabisic (4
, 3, 0)-5-nonene, 1,8-diazabisic (5
, 4,0)-7-Undecene (DBU), etc., heated and stirred at 50 to 120°C, poured into water, extracted with an organic solvent such as toluene, recrystallized, or purified by column. It can be obtained as an oil or solid. The method for synthesizing the compound represented by the general formula (2) uses the phthalonitrile compound of the general formula (1) as a raw material, a preferable metal derivative corresponding to M in the general formula (2), and a suitable solvent. A compound represented by the general formula (2) can be obtained by reacting the compound in the reactor. For example, a phthalonitrile compound of general formula (1) and a metal derivative can be prepared using ammonium molybdate, or DBU as a catalyst in urea, alcohol, or a high-boiling solvent such as trichlorobenzene, chloronaphthalene, sulfolane, etc. The reaction is carried out at 100 to 250°C, the solvent is removed, and the compound of general formula (2) is obtained as a blue or green solid or liquid by column purification or the like.

The optical recording medium in which the near-infrared absorber of this invention is used is
It is manufactured by forming a recording film containing a near-infrared absorbent represented by the general formula (2) on a substrate, and then providing a metal reflective film on the recording film.

Preferred specific examples of the cyanine near-infrared absorbent according to the present invention include α-tetra(2-ethylhexyl)Cu cyanine, α-tetra(2-ethylhexyl), α-tetra(2-ethylhexyl),
-ethylhexyloxy)Niphthalocyanine, α-tetra(2-ethylhexyloxy)Pdphthalocyanine, α-tetra(1,3-dimethylbutoxy)Pdphthalocyanine, α-tetra(2,6-dimethyl- 4-hebutoxy)Niphthalocyanine, a-tetra(2,4-
dimethyl-3-benxoxy) Pd lid cyanine α
-tetra(4-tert-butylcyclohexyloxy) Ni phthalocyanine, α-tetra(3-butoxyl)
Ni phthalocyanine, α-tetra(2,5-dimethyl-
Examples include (3-hexyloxy) Zn futacyanine, α-tetra (2,5-dimethyl-3-hexyloxy) Fe fth cyanine, α-tetra (1-methylnonyloxy) SiCh fth cyanine, and the like.

The substrate used in the optical recording medium of the present invention is preferably one through which light for recording or reading signals passes. It is desirable that the light transmittance is 85% or more and the optical anisotropy is small.
For example, acrylic resin, polycarbonate resin,
Allyl resin, polyester resin, polyamide resin,
Preferred examples include various plastics such as vinyl chloride resins, polyvinyl ester resins, epoxy resins, and polyolefin resins. Among these exemplified products, acrylic resins, polycarbonate resins, polyolefin resins, and other injection molding resins are preferred from the viewpoint of the mechanical strength of the substrate, the ease of providing guide grooves and reproduction-only signals, and economic efficiency. , polycarbonate resin is more preferred. The shape of these substrates may be plate-like, film-like, circular, or card-like. Of course, the surface of the substrate may have guide grooves for indicating recording positions, bits for reproduction-only information, etc. It is preferable that such guide grooves or bits be provided when the substrate is manufactured by injection molding or casting.
It can also be applied by superimposing it on a stamper and exposing it to ultraviolet light. In the optical recording medium of the present invention, a recording layer containing the dye described above is first formed on such a substrate, and a metal reflective film layer is formed thereon. Metals used as the reflective layer include Ag, Au, Cu.
Examples include Pt, and this reflective layer is usually formed by a method such as vacuum evaporation or sputtering. In order to form the recording layer containing the dye on the substrate in the optical recording medium of the present invention, a coating method or a vapor deposition method may be used, but the coating method is preferable from the viewpoint of productivity. To form a film by the coating method, a solution consisting of a dye and an organic solvent is brought into contact with the substrate and the dye is fixed on the substrate.More specifically, for example, the dye solution is caused to flow down onto the substrate. or after bringing the surface of the substrate into contact with the liquid level of the dye solution and pulling it up, removing excess dye solution while rotating the substrate, or allowing the dye solution to flow down onto the substrate while rotating the substrate, etc. There is. Further, if necessary, forced drying treatment may be performed after these treatments. In the coating method, ordinary organic solvents can be used to dissolve the dye of this invention, but direct coating onto the injection molded substrate used in this invention is possible. Solvents that do not damage the substrate include aliphatic and cycloaliphatic hydrocarbons such as hexane, hebutane, octane, decane, cyclohexane, and methylcyclohexane, and ethers such as diethyl ether, dibutyl ether, and diisobutylene ether. Non-polar solvents such as methyl alcohol, ethyl alcohol, isobrobyl alcohol, allyl alcohol, methyl cellosolve and other alcohol-based polar solvents are preferred. In relation to the solubility in the above-mentioned solvent, it is preferable that the substituents R1, R2, R3 and R4 of the dye have 3 or more carbon atoms. On the other hand, the substituent, R1
, R2, R3, and R4 are 13 or more carbon atoms, which is not preferable because the melting point of the dye becomes low and the recording layer is damaged when a metal reflective layer is formed. In addition, when this recording layer is formed, in order to improve the recording characteristics or prevent the formation of bottle holes, dyes other than the above-mentioned dyes, such as substituted cyanine, are added.
Organic dyes such as substituted naphthalocyanines, substituted volufiline dyes, cyanine dyes, dithiol metal complexes, anthraquinone dyes, nitrocellulose, ethyl cellulose,
It is also possible to use resins such as acrylic resin, polystyrene resin, and urethane resin, as well as other leveling agents and antifoaming agents.

The optical recording medium of this invention is compatible with CD drives. From the viewpoint of compatibility with this CD player, it is required that the reflectance of the readout laser beam through the substrate be 60% or more, and more preferably 65% or more. A reflectance of 60% or more can be achieved by optimizing the thickness of the recording layer when using the near-infrared absorber of the present invention.
In the case of this invention, the film thickness is approximately 50 to 300 nm. Furthermore, from the viewpoint of this reflectance, the substituents R1, R2
, R3 and R4 are preferably branched alkyl groups. The reason for this is presumed to be that the refractive index of the near-infrared absorber increases due to the branched alkyl group. In the optical recording medium of the present invention, signals are recorded and read by irradiating a laser beam through the substrate, and the wavelength of the laser beam used is usually a semiconductor laser having an oscillation wavelength in the range of 640 to 850 nm. Yes, but
Considering compatibility with commercially available CD players, 790
It is particularly preferable that the range is ±20 nm. Then, for example, 1.2~+. When recording is performed at a linear velocity of 4 m/s, the laser output on the recording film is:
It is approximately 5 to 12 mW, and in the case of reading, it is appropriate that the laser output is approximately 1/10 of that during recording.

In the practical use of the optical recording medium of the present invention, in order to protect the recording layer and the metal reflective layer, an ultraviolet curing resin or a thermosetting resin is usually coated on the reflective layer.

[Preferred Modes for Carrying Out the Invention] The present invention will be specifically explained below with reference to Examples.
The technical scope of this invention is not limited by these examples. Example 1 Synthesis of CH co(1-a) 42 parts of 2-dodecanol was mixed with 230 parts of dimethylformamide.
After adding 9 parts of 60% sodium hydride under a nitrogen atmosphere, 32 parts of 3-nitrophthalonitrile and 120 parts of dimethylformamide were added at 10 to 15°C.
of the mixed solution was added dropwise and stirred for 24 hours. The reaction mixture was poured into 6,000 parts of diluted hydrochloric acid and extracted with 1,000 parts of toluene. The toluene layer was separated, washed with hot water, and the solid content was filtered off, followed by distilling off the solvent.
The residue was purified by silica gel/toluene column,
31 parts of purified product was obtained as a white powder. The yield was 53%. From the analysis results below, we confirmed that it was the desired product. The IR spectrum is shown in FIG.

Elemental analysis 202. HzsN20 Mass spectrum m/e: 312 (M”)IR
Spectrum: 2220cm-' (-C=
N) 2.5 parts of the phthalonitrile derivative represented by the above structural formula (1-a), 0.2 parts of cuprous chloride, and 1.8 parts of cuprous chloride.
-Diazabishic mouth (5,4,0)-7-undecene
A mixture of 1.2 parts of n-amyl alcohol and 80 parts of n-amyl alcohol was heated under reflux for 5 hours. After solvent distillation, the residue was purified by column (silica gel/hexane; toluene - 2:5)
L, 1.0 part of a cyanine compound represented by the following structural formula (2-11) and its isomer were obtained as a blue viscous oil. The yield was 38%. The λmax in the solution was 740 nm, and the elemental analysis values were as follows. The IR spectrum is shown in Figure 2. Elemental analysis: C+oHzJa04Cu Next, the depth of 70 nm, width of 0.6 μ, pitch of 1.6 μ Thickness 1.2mm, diameter 1 with spiral guide groove
After dropping a 0.4% octane solution of the cyanine dye having the structural formula (2-1) onto the center of the guide groove surface of a 20 mm injection molded polycarbonate resin substrate, the resin substrate was heated at 1000 rpm. It was rotated at a speed of 10 seconds. Next, this resin substrate was dried in an atmosphere at 40° C. for 10 minutes to fix the first layer of the recording layer consisting essentially only of the naphthalocyanine dye on the resin substrate. The thickness of this first dye layer was 1200 m.
A gold reflective film with a thickness of 60 mm was formed on this first layer by sputtering, and a protective coating film made of an ultraviolet curable resin was further provided on the gold reflective film to produce a recording medium. It was done. This optical recording medium was placed on a turntable for a length of 1.4 m.
While rotating at a linear velocity of /s, a drive equipped with an optical head equipped with a semiconductor laser with an oscillation wavelength of 785 nm is used to control the laser beam to focus on the recording layer on the guide groove through the resin substrate, while measuring the reflectance. When measured, the reflectance was 72%. Next, the laser output was 8 mW on the recording surface, the pulse width was 500 ns,
An I MHz pulse signal was recorded. Next, using the same device, the semiconductor laser output was 1 mW on the recording surface.
The recorded signal was read out as follows. At this time, a signal-to-noise ratio CN value of 55 dB was obtained, and extremely good recording and reading could be performed. In addition, EMF modulation signals were recorded in the same manner and the block error rate was measured. The block error rate was 3×10-', which was extremely good. Almost no distortion was observed in the waveform of the recorded signal. In order to test the stability of the reproducing light of this recording film, this recorded signal was repeatedly and continuously read out from the same track 500,000 times using a readout light of 1 mW, but no change was observed in the magnitude of the recorded signal or the CN value. I couldn't.

Furthermore, in order to test the durability of this optical recording medium, it was heated at 60°C.
After being left in a high temperature, high humidity atmosphere of 90% RH for 3 months to test the light resistance, the reflectance of the recording film was measured and the recording signal was measured after being left for 200 hours using a Weatherometer and a Riki-bon arc. The data was reread and rerecorded. The reflectance did not change much from the initial value. In addition, the CN value is 54 dB for re-reading, and 55 dB for re-recording.
values were obtained, and there was almost no deterioration of the recording film in the durability test and light resistance test.

Example 2 Synthesis of (1-b) 20 parts of 2,6-dimethyl-4-hebutanol was dissolved in 140 parts of dimethylformamide, and 60 parts of 2,6-dimethyl-4-hebutanol was dissolved in 140 parts of dimethylformamide.
After adding 6 parts of sodium hydride, 20 parts of 3-nitrophthalonitrile and dihydride were added at lO to 15°C. A mixed solution of 70 parts of formamide was added dropwise for 2 hours.
Stirred. The reaction mixture was poured into 4000 parts of diluted hydrochloric acid, and then extracted with 1000 parts of toluene.
The toluene layer was separated, washed with hot water, the solid content was filtered off, and the solvent was distilled off. The residue was purified using a silica gel/toluene column to obtain 24.8 parts of a purified product as a yellow liquid. The yield was 76%.

The following analysis results confirmed that it was the desired product.
The IR spectrum is shown in Figure 3. Elemental analysis: Cl
7}12■Nz0 Mass spectrum m/e: 270 (M") IR Spectrum 2220 cm-' (-C-N) 10 parts of the nitonyl derivative represented by the above structural formula (1-b) and 1.2 parts of nickel chloride. A mixture of 1 part of 1,8-diazabicyclo(5,4,0)-7-undecene and 200 parts of n-amyl alcohol was heated to reflux for 5 hours. After distilling off the solvent, the remaining The product was purified by a silica gel/toluene column, and 3.0 parts of a futacyanine compound represented by the following structural formula (2-2) and its isomer were obtained as a dark green powder. Yield was 29%. CH. The λmax elemental analysis value of this dye in a hexane solution was as follows. The IR spectrum is shown in Figure 4. Elemental analysis: Caa}IaaNsOJi was 695 nm. An optical recording medium was manufactured and tested in the same manner as in Example 1. CN was used under the recording conditions of a reflectance of 70% and a recording sensitivity of 8 mW.
if1 is 54 dB, block error rate is 5X10
It was -3. Further, there was no abnormality in reproduction light stability, durability, or light resistance.

Example 3 Synthesis of (1-c) 16.2 parts of 2,4-dimethyl-3-hebutanol was dissolved in 140 parts of dimethylformamide, and 6 parts of 60% sodium hydride was added under a nitrogen atmosphere. 0～
A mixed solution of 20 parts of 3-nitrophthalonitrile and 70 parts of dimethylformamide was added dropwise at 5°C.
Stir for an hour. The reaction mixture was transferred to 4000 parts of diluted hydrochloric acid and diluted with toluene.
After extraction with 1000 parts, the toluene layer was separated, washed with hot water, the solid matter was filtered off, and the solvent was distilled off. The residue was purified by a silica gel/toluene column to obtain 15 parts of a purified product as a white powder.

The yield was 50%. The following analysis results confirmed that it was the desired product.
The IR spectrum is shown in Figure 5. Elemental analysis: C+s
HraNx0 mass spectrum m/e: 242 (M”)I
R spectrum: 2210cm-” (-C=
N) 8.2 parts of the cap nitonyl derivative represented by the above structural formula (1-c), 4.3 parts of palladium chloride and 1.8 parts
5.
A mixture of 2 parts and 200 parts of n-7 methyl alcohol was heated to reflux for 10 hours. After distilling off the solvent, the residue was purified using a 1:l column of silica gel/toluene:hexane to obtain 0.8 parts of a capcyanine compound represented by the following structural formula (2-3) and its isomer. Obtained as a dark green powder. The yield was 8.2%. The λmax elemental analysis value of this dye in a hexane solution was as follows. The IR spectrum is shown in Figure 6. Elemental analysis: CaoHyzNaO4Pd was 692 nm Next, an optical recording medium was produced and tested in the same manner as in Example 1. Reflectance is 70%, recording sensitivity is 9mW, CN value is 56 dB, block error rate is 3X
It was 10-'. There were no abnormalities in reproduction light stability, durability, or light resistance. Comparative Example 1 An optical recording medium was produced and tested in the same manner as in Example 1, except that a lid cyanine compound having the following structural formula (A) was used. Under recording conditions with a reflectance of 65% and a recording sensitivity of 12 mW,
CN value is 50 dB, block error rate is 3X10
-' and could not meet the CD standards. It was also observed that the signal of the recorded bits had a large amount of distortion. Examples 4 to 12 Using the alcohols listed in Table 1 and 3-nitrophitrile, the lidding nitrile compound (1-d-1-1) of the present invention was synthesized in the same manner as in Example 1. did. It was confirmed to be the desired product by elemental analysis, MS, and IR. Next, these phthalonitrile compounds (1-d-1-1)
Using the metal salts listed in Table 2, the lid cyanine compounds (2-4 to 2-12) were synthesized in the same manner as in Example 1. The structure was confirmed by mass spectrum and elemental analysis. Table 2 shows the λmax of these dyes in solution. In addition, optical recording media made using these dyes are
Both reflectance, recording sensitivity, block error rate,
It had good performance in terms of playback light stability, durability, and light resistance. Table 1 Table 2 [Effects of the Invention] As clearly recognized from the Examples, when the near-infrared absorbent of the present invention is used in the recording layer of an optical recording medium,
All of them have a reflectance of 65% or more, giving excellent C/N values and block error rates, and their characteristics hardly change in any of the tests of reproduction light stability, durability, and light resistance. It has made it possible to provide an extremely superior optical recording medium that combines excellent performance and high reliability.

[Brief explanation of drawings]

Claims (1)

[Claims] 1. Phthalonitrile compound represented by general formula (1) ▲ Numerical formula, chemical formula, table, etc. ▼ (1) [In formula (1), R represents an unsubstituted or substituted alkyl group. [In formula (2), R^1, R^2, R^3 and R^4 are each independently unsubstituted or It represents a substituted alkyl group, and M represents two hydrogen atoms, a divalent metal atom, a monosubstituted trivalent metal atom, a disubstituted tetravalent metal atom, or an oxymetal atom. ] A phthalocyanine near-infrared absorber represented by: 3. A recordable optical recording medium having a reflectance of 60% or more for the readout laser beam through the substrate, compatible with compact disc players, and comprising a transparent injection molded resin substrate; 3. An optical recording medium essentially comprising a recording layer provided on the recording layer and a metal reflective layer, the recording layer containing the near-infrared absorber according to claim 2. 4. The optical recording medium according to claim 3, wherein the reflectance of the readout laser beam through the substrate is 65% or more. 5. The phthalonitrile compound according to claim 1, wherein the substituent R in formula (1) is an alkyl group having 3 to 12 carbon atoms. 6. R^1, R^2, R^3 and R^4 in formula (2)
The near-infrared absorbent according to claim 2, wherein is an alkyl group having 3 to 12 carbon atoms. 7. The optical recording medium according to claim 3 or 4, wherein the recording layer contains the near-infrared absorber according to claim 6. 8. The phthalonitrile compound according to claim 5, wherein the substituent R in formula (1) is a branched alkyl group. 9. R^1, R^2, R^3 and R^4 in formula (2)
The near-infrared absorbent according to claim 6, wherein is a branched alkyl group. 10. The optical recording medium according to claim 3 or 4, wherein the recording layer contains the near-infrared absorber according to claim 9. 11. The optical recording medium according to any one of claims 3, 4, 7, or 10, wherein the wavelength of the reading laser beam is 790±20 nm.