JP2005120350A - Azo metal chelate dyestuff and optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an azo metal chelate dyestuff capable of high-speed recording on an optical recording medium. <P>SOLUTION: The azo metal chelate dyestuff is a compound formed by forming a chelate bond between an azo dyestuff compound having a 1,3,4-thiadiazole ring as a diazo component to which a coupler component having a fluorine-substituted alkylsulfonylamino group and an amino group condensed to form a condensed ring is bonded and at least one metal selected from the group consisting of Co, Ni, Cu and Pd wherein an absorbance ratio (OD2/OD1) of absorption peaks in two absorption bands found in absorption spectrum measured at a wavelength ranging from 400 nm to 800 nm is larger than 1.25. An optical recording medium capable of high-speed recording is provided by using the azo metal chelate dyestuff. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an azo metal chelate dye suitable for high-speed recording, and more specifically, an azo metal chelate dye exhibiting a specific film absorption spectrum and an optical recording medium using the azo metal chelate dye (in the present invention, optical The recording medium may be referred to as “disk” or “optical disk”).

  In recent years, the size of data that can be handled has increased with the increase in the speed of computers and the increase in hard disk capacity. In order to cope with this, the recording medium has been required to have a large capacity, and a DVD-R has been developed as a large capacity recordable CD. Various dyes such as cyanine and metal chelate dyes have been proposed for use in the recording layer of DVD-R. Among these dyes, many optical recording media using metal chelate dyes excellent in light resistance and weather resistance have been proposed (see Patent Document 1).

  There is also a report on an azo metal chelate dye formed by an azo dye compound obtained from a diazo component having a nitrogen atom and a coupler component having an alkylsulfonylamino group substituted with fluorine (see Patent Document 2). Furthermore, by using an azo metal chelate dye of an azo dye compound and a metal using a coupler component in which an amino group on the benzene ring is condensed to the benzene ring as a recording layer of an optical recording medium, There is a report that it is possible to improve recording characteristics such as light resistance and durability of an optical recording medium (see Patent Document 3).

JP-A-3-268994 JP 11-166125 A JP 2000-309722 A

  Recently, as the amount of data further increases, increasing the recording speed for recording information on an optical recording medium is emphasized. For example, in DVD-R, the normal recording speed is about 3.5 m / s (hereinafter sometimes referred to as 1X), but about 28 m / s (hereinafter referred to as 8X), which is eight times the 1X. There is a need in the market for an optical recording medium capable of recording information at the above high recording linear velocity.

  In order to meet the demands of the market, development of a dye particularly suitable for high-speed recording has been an issue.

  In view of the above problems, an object of the present invention is to provide an azo metal chelate dye capable of high-speed recording and an optical recording medium using the azo metal chelate dye.

  In view of the fact that it is difficult to increase the reflectance of the optical recording medium in high-speed recording, and that the reflectance of the optical recording medium can be increased by increasing the refractive index of the recording layer. The aim was to obtain an azo metal chelate dye having a refractive index. Specifically, the present inventors have measured the absorption spectrum of a coating film containing a dye, the absorption peak on the long wavelength side of the absorption band existing at 500 nm to 700 nm or the absorbance at the absorption shoulder: OD2. Attention was focused on the absorption peak on the short wavelength side or the absorbance at the absorption shoulder: OD1. The inventors have found that the refractive index of the dye can be increased by increasing the value of OD2 / OD1 above a predetermined value, and have completed the present invention.

That is, the gist of the present invention is an azo metal chelate dye comprising an azo dye compound and a metal, wherein OD2 / OD1 measured by the following measurement method is greater than 1.25. Exist.
(Measurement method of OD2 / OD1)
(1) After 20 mg of an azo metal chelate dye is contained in 2 g of an octafluoropentanol (OFP) solvent, ultrasonic dispersion is performed at 50 ° C. to 55 ° C. for 60 minutes to obtain a solution A. Solution A is cooled to room temperature (25 ± 5 ° C.) to obtain solution B.
(2) The solution B is spin-coated on a polycarbonate substrate at a rotation speed of 800 rpm. Then, the substrate coated with the solution B is held at 80 ° C. for 5 minutes. The substrate thus coated with the solution B is referred to as a coated substrate A.
(3) The absorption spectrum at 400 nm to 800 nm of the coated substrate A is measured.
(4) Among the absorption peaks observed at 500 nm to 700 nm in the obtained absorption spectrum, the absorbance of the absorption peak on the long wavelength side of the absorption peak having the largest absorbance and the absorbance peak next to that is OD2, OD2 / OD1 is calculated with the absorbance at the absorption peak on the short wavelength side as OD1.

Another gist of the present invention is an optical recording medium having a recording layer on which information is recorded and / or reproduced by irradiated light on a substrate, the recording layer comprising an azo dye compound and a metal. An azo metal chelate dye comprising: an azo metal chelate dye measured by the following measurement method, wherein OD2 / OD1 is greater than 1.25.
(Measurement method of OD2 / OD1)
(1) After 20 mg of an azo metal chelate dye is contained in 2 g of an octafluoropentanol (OFP) solvent, ultrasonic dispersion is performed at 50 ° C. to 55 ° C. for 60 minutes to obtain a solution A. Solution A is cooled to room temperature (25 ± 5 ° C.) to obtain solution B.
(2) The solution B is spin-coated on a polycarbonate substrate at a rotation speed of 800 rpm. Then, the substrate coated with the solution B is held at 80 ° C. for 5 minutes. The substrate thus coated with the solution B is referred to as a coated substrate A.
(3) The absorption spectrum at 400 nm to 800 nm of the coated substrate A is measured.
(4) Among the absorption peaks observed at 500 nm to 700 nm in the obtained absorption spectrum, the absorbance of the absorption peak on the long wavelength side of the absorption peak having the largest absorbance and the absorbance peak next to that is OD2, OD2 / OD1 is calculated with the absorbance at the absorption peak on the short wavelength side as OD1.

  According to the present invention, an azo metal chelate dye capable of high-speed recording and an optical recording medium capable of high-speed recording using the azo metal chelate dye are provided.

Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment of the present invention) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.
In the present embodiment, an azo metal chelate dye composed of an azo dye compound and a metal, and an azo metal chelate dye having an OD2 / OD1 greater than 1.25 measured by a predetermined measurement method is used.

The point which makes OD2 / OD1 into a predetermined value in this Embodiment is demonstrated.
As a method for performing high-speed recording, a method using a dye having a higher absorbance (absorption) at a recording wavelength is conceivable so as to efficiently absorb a recording laser beam. This is a method of making the wavelength of the maximum absorption of the dye longer than that of the dye conventionally used in low-speed recording. However, when such a long-absorbing dye is used, the reflectance of the disk tends to be lower than before. For this reason, in the above method, it is often difficult to satisfy the specification of the reflectance defined by the optical disc, for example, the standard for the recording portion reproduction of “disc reflectance of 45% or more” in DVD. Therefore, when the above method is used, there are many cases where the reflectance must be ensured at the expense of recording sensitivity to some extent.

In the present embodiment, the present inventors have found a dye for high-speed recording that can obtain a sufficient reflectivity even in high-speed recording and has excellent recording sensitivity by changing the point of focus. This will be further described below.
First, in the specific film thickness range (90 nm or less), the inventors can obtain a higher disk reflectivity as the refractive index of the dye film (recording layer) increases (for example, Japanese Patent Laid-Open No. 10-208303). The aim was to obtain an azo metal chelate dye having a higher refractive index, based on the knowledge of the publication No. 1 to FIG.

On the other hand, in the absorption spectrum of the azo metal chelate dye film, an absorption band considered to be due to an electronic state localized in the ligand, an absorption band considered to be caused by the interaction between the metal and the ligand, These two absorption bands are observed at 500 nm to 700 nm (see FIG. 1; FIG. 1 will be described later).
In the present embodiment, of the two absorption bands seen from 500 nm to 700 nm, the absorbance of the absorption peak on the short wavelength side is OD1, and the absorption peak on the long wavelength side is OD2. The inventors have found that an azo metal chelate dye having a particularly high refractive index can be obtained by making OD2 / OD1 larger than 1.25. As a result, an optical recording medium having sufficient reflectivity even in high-speed recording can be obtained. This OD2 / OD1 is measured by the following method.

(Measurement method of OD2 / OD1)
(1) After 20 mg of an azo metal chelate dye is contained in 2 g of an octafluoropentanol (OFP) solvent, ultrasonic dispersion is performed at 50 ° C. to 55 ° C. for 60 minutes to obtain a solution A. Solution A is cooled to room temperature (25 ± 5 ° C.) to obtain solution B.
(2) The solution B is spin-coated on a polycarbonate substrate at a rotation speed of 800 rpm. Then, the substrate coated with the solution B is held at 80 ° C. for 5 minutes. The substrate thus coated with the solution B is referred to as a coated substrate A.
(3) The absorption spectrum at 400 nm to 800 nm of the coated substrate A is measured.
(4) Among the absorption peaks observed at 500 nm to 700 nm in the obtained absorption spectrum, the absorbance of the absorption peak on the long wavelength side of the absorption peak having the largest absorbance and the absorbance peak next to that is OD2, OD2 / OD1 is calculated with the absorbance at the absorption peak on the short wavelength side as OD1.

Hereinafter, each process of said (1)-(4) is demonstrated.
First, 20 mg of an azo metal chelate dye to be measured is contained in 2 g of an octafluoropentanol (OFP) solvent, and then ultrasonic dispersion is performed at 50 ° C. to 55 ° C. for 60 minutes to obtain a solution A. Ultrasonic dispersion is performed in order to dissolve or disperse the azo metal chelate dye in the solvent. For ultrasonic dispersion, a conventionally known method may be used.

  Next, the solution A is cooled to room temperature (25 ± 5 ° C.) to obtain a solution B. As a method for cooling the solution A, the solution A is allowed to cool at room temperature. It is not preferable to quench the solution A with ice water or the like because excessive crystallization may be promoted. Here, after cooling the solution A to room temperature, it is preferable to filter the solution A with a filter (for example, 0.2 μm). Examples of the filter include a Teflon (registered trademark) filter manufactured by Millipore Corporation. By filtering with a filter, undissolved components and insufficiently dispersed components in the solution A can be removed. The solution thus obtained is referred to as Solution B. However, if undissolved pigment is observed in solution A, the supernatant may be collected and used as solution B.

As is clear from the above description, in the “solution A”, all or a part of the azo metal chelate dye may be present in a state dissolved in the solution. Alternatively, in the “solution A”, all or a part of the azo metal chelate dye may be present in a dispersed state in the solution.
Further, the solution B is spin-coated on a polycarbonate substrate at a rotation speed of 800 rpm. As an apparatus for performing spin coating, a conventionally known apparatus used for forming a recording layer of CD-R or DVD-R can be used. Specifically, the coating film made of the solution B may be formed on the polycarbonate substrate by dropping the solution B onto the polycarbonate substrate rotated at a rotation speed of 800 rpm.

  Thereafter, the substrate coated with the solution B is held at 80 ° C. for 5 minutes. This is to remove the solvent in the solution B. It is preferable that the solvent is completely removed from the solution B by maintaining at 80 ° C. for 5 minutes. However, the solvent may not be completely removed as long as the absorption spectrum described below can be measured satisfactorily.

  The substrate thus coated with the solvent B is referred to as a coated substrate A. The absorption spectrum of this coated substrate A at 400 nm to 800 nm is measured. A conventionally well-known method should just be used for the measurement of an absorption spectrum. Specifically, sample light (400 nm to 800 nm) for absorption spectrum measurement is irradiated from the substrate side of the coated substrate A. Then, air may be used as a reference sample, the intensity of light in the reference sample and the intensity of light that has passed through the coated substrate A may be measured, and the absorption spectrum in the coated substrate A may be measured.

The following method can be mentioned as a more specific method of an absorption spectrum.
A disk coated with an azo metal chelate dye film is cut out in a fan shape and measured by irradiating light from the surface opposite to the dye film (surface on the substrate side) with an ultraviolet / visible spectrophotometer. The spectroscope used for measurement and the measurement conditions may be normal conditions of a commercially available apparatus. For example, in an example of the present embodiment, U-3300 manufactured by Hitachi, Ltd. was used. The measurement conditions were as follows: wavelength scan speed 300 nm / min. In the absorbance measurement (Absorbance) mode with a sampling period of 0.5 nm.

  The higher the OD2 / OD1 value obtained by such a method, the higher the refractive index. FIG. 2 is a graph showing the relationship between OD2 / OD1 and the refractive index in the dye films of various azo metal chelate dyes to which the present embodiment is applied. From the measurement result of FIG. 2, it is clear that the higher the value of OD2 / OD1, the higher the refractive index. According to the measurement result of FIG. 2, the maximum value of the refractive index of the film of 1.25 or more of the present embodiment corresponds to about 3.3.

  The value of OD2 / OD1 is greater than 1.25, preferably 1.26 or more, more preferably 1.27 or more, and even more preferably 1.28 or more, since sufficient reflectance can be obtained for high-speed recording applications. Preferably it is 1.29 or more. Further, the value of OD2 / OD1 is preferably as large as possible for the purpose of the present invention, but is preferably 5 or less, more preferably 3 or less. If it is larger than 5, the absorption wavelength dependence may be increased because the width of the absorption band is narrow.

  In addition, as a result of measuring the absorption spectrum of the azo metal chelate pigment | dye film | membrane by the said measuring method, two or more absorption peaks may not be confirmed clearly in 500 nm-700 nm. As such an example, for example, a case where an absorption spectrum of 500 to 700 nm is observed as an absorption spectrum having a plurality of absorption shoulders. In this case, OD2 / OD1 may be calculated using the absorption peak or absorption shoulder having the maximum absorbance among the obtained peaks and the absorption peak or absorption shoulder having the next largest absorbance.

  FIG. 5 is a diagram showing an example in which the absorption spectrum of the dye film of the azo metal chelate dye has an absorption shoulder. As an example, how to obtain OD2 / OD1 will be described for an absorption spectrum as shown in FIG. When an absorption spectrum as shown in FIG. 5 is obtained, the absorption shoulder observed on the short wavelength side of the absorption spectrum of 400 to 700 nm may be OD1.

  A preferred example of the dye having a high OD2 / OD1 value is an azo metal chelate dye having a specific structure. It has been found that a disk using these dyes in the recording layer stably exhibits high reflectivity even when the absorption maximum wavelength of the recording layer is long, as compared with a disk using a dye conventionally used in the recording layer.

Hereinafter, an example of the azo metal chelate dye having the specific structure will be described.
First, a 1,3,4-thiadiazole ring among the hetero rings having a nitrogen atom is used as a diazo component. Then, an azo dye compound is synthesized by combining this diazo component, a fluorine-substituted alkylsulfonylamino group, and a coupler component having a condensed amino group. A recording layer containing an azo metal chelate dye formed from this azo dye compound and a metal is preferable because it may be excellent in light resistance and weather resistance. Furthermore, an azo metal chelate dye in which the 1,3,4-thiadiazole ring of the diazo component is substituted with a hydrogen atom or an ester group tends to have an OD2 / OD1 value that satisfies the requirements of the present embodiment, which is preferable. . This is because the coordination of the azo-based ligand and the metal ion can be achieved by making the substituent of the diazo component the smallest sterically structural hydrogen atom, or by making the substituent itself a highly polar ester group. This may be due to the fact that it can occur in a state with little steric hindrance. As a specific example of such a structure,

(In the formula, R ₁ is a hydrogen atom or an ester group represented by CO ₂ R ₃ , and R ₃ is a linear or branched alkyl group which may be substituted, or a cycloalkyl group which may be substituted. R ₂ is a linear or branched alkyl group which may be substituted, at least one of X ₁ or X ₂ is an NHSO ₂ Y group, and Y is substituted with at least two fluorine atoms. R _{4 and} R ₅ are each independently a hydrogen atom or an optionally substituted linear or branched alkyl group, and R _6, R _7, R ₈ and R ₉ is independently a hydrogen atom or an alkyl group having 1 to 2 carbon atoms.)

  The azo metal chelate dye to which this embodiment is applied is formed by chelate bonding between the azo dye compound represented by the above formula (1) and a metal. Further, the azo dye compound represented by the formula (1) is formed by combining a coupler component having a 1,3,4-thiadiazole ring as a diazo component and a fluorine-substituted alkylsulfonylamino group and a condensed amino group. Is done.

The substituent R ₁ in the diazo component is a hydrogen atom or an ester group represented by CO ₂ R ₃ , and R ₃ is a linear or branched alkyl group which may be substituted, or a cyclo which may be substituted. It is an alkyl group. The substituent of R ₃ is not particularly limited as long as it is a typical element such as oxygen, nitrogen, sulfur other than a halogen atom. As R ₃ , for example, an unsubstituted linear or branched alkyl group, or an unsubstituted cycloalkyl group, a linear or branched alkyl group substituted with fluorine, or a linear chain substituted with an alkoxy group Or a branched alkyl group is preferable. R ₃ is particularly preferably a hydrogen atom; a linear or branched group having 1 to 4 carbon atoms, such as an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, or a sec-butyl group. An alkyl group; a cycloalkyl group having 3 to 8 carbon atoms such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group; Particularly preferred are a straight-chain alkyl group having 1 to 2 carbon atoms such as a methyl group or an ethyl group; and a cycloalkyl group having 3 to 6 carbon atoms such as a cyclopentyl group or a cyclohexyl group because of its small steric hindrance.

The substituent R ₁ in the diazo component is most preferably a hydrogen atom having the smallest steric hindrance from the viewpoint of satisfying the predetermined OD2 / OD1 in the present embodiment. As a specific compound of such a diazo component, a compound having a structure of the following (Chemical Formula 2) is preferable.

At least _one of X ₁ and X ₂ in the coupler component represents NHSO ₂ Y. In this case, either X ₁ or X ₂ is preferably NHSO ₂ Y, and more preferably, X ₁ is NHSO ₂ Y. X ₁ is or _{X 2} when the NHSO ₂ Y, _{X 1} at the time of the _{X 2} and NHSO ₂ Y is not particularly limited, may be a hydrogen atom from the ease of synthesis.

  Y is a linear or branched alkyl group substituted with at least two fluorine atoms. As the alkyl group, a linear or branched alkyl group having 1 to 6 carbon atoms is more preferable. Y is more preferably a linear alkyl group having 1 to 3 carbon atoms. The number of fluorine atoms to be substituted is usually 2 or more, and is usually 7 or less, preferably 5 or less, more preferably 3 or less. Specific examples of Y include difluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluoropropyl group, 2,2,2-trifluoroethyl group, 3,3,3-trifluoropropyl group, and the like. Can be mentioned. Y is particularly preferably a trifluoromethyl group or a 2,2,2-trifluoroethyl group.

R _{4 and} R ₅ are each independently a hydrogen atom or an optionally substituted linear or branched alkyl group. Examples of R _{4 and} R ₅ include:
Hydrogen atom;
A linear alkyl group having 1 to 6 carbon atoms such as methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group;
A branched alkyl group having 3 to 8 carbon atoms such as isopropyl group, sec-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclopropyl group, cyclohexylmethyl group;
Halogen atoms such as fluorine, chlorine, bromine and iodine;
Methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, t-butoxy group, n-pentyloxy group, cyclopropyloxy group, cyclohexylmethyloxy group, 2 An alkoxy group having 1 to 8 carbon atoms such as an ethylhexyloxy group;
Methoxycarbonyl group, ethoxycarbonyl group, n-propoxycarbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl group, isobutoxycarbonyl group, sec-butoxycarbonyl group, t-butoxycarbonyl group, n-pentyloxycarbonyl group, cyclo An alkoxycarbonyl group having 2 to 9 carbon atoms such as a propyloxycarbonyl group, a cyclohexylmethoxycarbonyl group, and a 2-ethylhexyloxycarbonyl group;
Methylcarbonyloxy group, ethylcarbonyloxy group, n-propylcarbonyloxy group, isopropylcarbonyloxy group, n-butylcarbonyloxy group, isobutylcarbonyloxy group, sec-butylcarbonyloxy group, t-butylcarbonyloxy group, n- An alkylcarbonyloxy group having 2 to 9 carbon atoms such as a pentylcarbonyloxy group, a cyclopropylcarbonyloxy group, a cyclohexylmethylcarbonyloxy group, and a 2-ethylhexylcarbonyloxy group;
From 2 carbon atoms such as acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, 2-methylbutyryl group, pivaloyl group, hexanoyl group, cyclopropylcarbonyl group, cyclohexylmethylcarbonyl group, 2-ethylhexylcarbonyl group, etc. 9 alkylcarbonyl groups;
Carbon number 2 such as dimethylamino group, diethylamino group, dipropylamino group, diisopropylamino group, dibutylamino group, diisobutylamino group, di-t-butylamino group, dihexylamino group, ethylmethylamino group, butylpentylamino group To 16 dialkylamino groups;
Etc.

In addition to the linear and branched alkyl groups and alkoxy groups, the substituents mentioned as R _{4 and} R ₅ may be further substituted. Of R _{4 and} R ₅ , a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, and an alkoxy group having 1 to 8 carbon atoms are preferable. R _{4 and} R ₅ are more preferably a hydrogen atom, an alkyl group having 1 to 2 carbon atoms, or an alkoxy group having 1 to 2 carbon atoms. The alkyl group and alkoxy group are preferably unsubstituted. R _{4 and} R ₅ are particularly preferably a hydrogen atom, a methyl group, an ethyl group, or a methoxy group.

R ₂ is a linear or branched alkyl group which may be substituted. As R ₂ , for example, a straight-chain alkyl group having 1 to 6 carbon atoms such as methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group; isopropyl group, sec-butyl group, isobutyl group, t- Examples thereof include branched alkyl groups having 3 to 8 carbon atoms such as a butyl group, a 2-ethylhexyl group, a cyclopropyl group, and a cyclohexylmethyl group.

These alkyl groups may be substituted. As a substituent,
Halogen atoms such as fluorine, chlorine, bromine and iodine; methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutoxy group, sec-butoxy group, t-butoxy group, n-pentyloxy group An alkoxy group having 1 to 8 carbon atoms, such as cyclopropyloxy group, cyclohexylmethyloxy group, 2-ethylhexyloxy group;
Methoxycarbonyl group, ethoxycarbonyl group, n-propoxycarbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl group, isobutoxycarbonyl group, sec-butoxycarbonyl group, t-butoxycarbonyl group, n-pentyloxycarbonyl group, cyclo An alkoxycarbonyl group having 2 to 9 carbon atoms such as a propyloxycarbonyl group, a cyclohexylmethoxycarbonyl group, and a 2-ethylhexyloxycarbonyl group;
Methylcarbonyloxy group, ethylcarbonyloxy group, n-propylcarbonyloxy group, isopropylcarbonyloxy group, n-butylcarbonyloxy group, isobutylcarbonyloxy group, sec-butylcarbonyloxy group, t-butylcarbonyloxy group, n- An alkylcarbonyloxy group having 2 to 9 carbon atoms such as a pentylcarbonyloxy group, a cyclopropylcarbonyloxy group, a cyclohexylmethylcarbonyloxy group, and a 2-ethylhexylcarbonyloxy group;
From 2 carbon atoms such as acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, isovaleryl group, 2-methylbutyryl group, pivaloyl group, hexanoyl group, cyclopropylcarbonyl group, cyclohexylmethylcarbonyl group, 2-ethylhexylcarbonyl group, etc. 9 alkylcarbonyl groups;
Carbon number 2 such as dimethylamino group, diethylamino group, dipropylamino group, diisopropylamino group, dibutylamino group, diisobutylamino group, di-t-butylamino group, dihexylamino group, ethylmethylamino group, butylpentylamino group To 16 dialkylamino groups;
Etc.

Among these, R ₂ is preferably an unsubstituted linear alkyl group having 1 to 6 carbon atoms or an unsubstituted branched alkyl group having 3 to 8 carbon atoms. When an unsubstituted linear alkyl group is used, the carbon number is usually 1 or more and 6 or less. The carbon number is preferably 5 or less, more preferably 4 or less. On the other hand, when an unsubstituted branched alkyl group is used, the carbon number is usually 3 or more and 8 or less. The carbon number is preferably 7 or less, more preferably 6 or less, still more preferably 5 or less, and particularly preferably 4 or less. R ₂ is particularly preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, or an isobutyl group.

R ₆ , R ₇ , R ₈ , and R ₉ each independently represent a hydrogen atom or an alkyl group having 1 to 2 carbon atoms. It is preferable to use a hydrogen atom or an alkyl group having 1 to 2 carbon atoms because OD2 / OD1 can be easily set to a predetermined value. In the alkyl group having 1 to 2 carbon atoms, the hydrogen atom bonded to the carbon atom may be substituted with another substituent (for example, a halogen atom), but is preferably an unsubstituted alkyl group. Examples of the alkyl group having 1 to 2 carbon atoms include a methyl group and an ethyl group. From the viewpoint of ease of synthesis and steric structure, hydrogen atoms are most preferable as R ₆ , R ₇ , R ₈ and R ₉ .

  The molecular weight of the azo dye compound represented by the general formula (1) is usually 2,000 or less. Of these, an azo dye compound having a molecular weight of 1,000 or less is preferable because solubility in a solvent is increased and a dye excellent in light resistance, weather resistance, and high reflectance can be obtained. Among the azo dye compounds represented by the general formula (1), specific examples of the compounds include the following (Chemical Formula 3 to Chemical Formula 30).

  There are no particular restrictions on the azo metal chelate dye other than the structure. However, from the viewpoint of use in an optical recording medium that can be recorded and reproduced with a short-wavelength laser beam that will be increasingly required in the future, a dye having an absorption maximum at a wavelength of 700 nm or less when measured for a dye monolayer film is more. A dye having an absorption maximum at a wavelength of 650 to 500 nm is more preferable.

  In the azo metal chelate dye to which the present embodiment is applied, various metals capable of forming a complex can be used as the metal that forms a chelate with the azo dye compound represented by the formula (1). As such a metal, an element of Group 9, Group 10, or Group 11 is preferable. Particularly preferred as such a metal is at least one selected from the group consisting of Co, Ni, Cu and Pd. This is because the use of the metal improves the shape of the absorption spectrum, and improves the solubility in various solvents, light resistance, and durability.

Hereinafter, an optical recording medium having an azo metal chelate dye to which the present embodiment is applied in a recording layer will be described.
The optical recording medium to which this embodiment is applied has a substrate and a recording layer containing an azo metal chelate dye having an OD2 / OD1 larger than 1.25. Preferably, the optical recording medium of the present embodiment has a substrate and a recording layer containing an azo metal chelate dye composed of an azo dye compound represented by formula (1) and a metal. The optical recording medium may have a layer structure in which an undercoat layer, a metal reflective layer, a protective layer, and the like are provided on a substrate as necessary. As an example of a preferable layer configuration, for example, a high reflectance optical recording medium in which a recording layer, a metal reflection layer and a protective layer are provided on a substrate can be mentioned.

Hereinafter, the optical recording medium to which the present embodiment is applied will be described by taking the optical recording medium having such a layer structure as an example.
The substrate material in the optical recording medium to which the present embodiment is applied basically has only to be transparent at the wavelengths of recording light and reproducing light. For example, polycarbonate resins, vinyl chloride resins, acrylic resins such as polymethyl methacrylate, polystyrene resins, epoxy resins, vinyl acetate resins, polyester resins, polyethylene resins, polypropylene resins, polyimide resins, amorphous Polymer materials such as polyolefin and inorganic materials such as glass are used. It is preferable to use a polycarbonate resin from the viewpoints of high productivity, cost, moisture absorption resistance, and the like.

  These substrates are formed into a disk shape by injection molding or the like. If necessary, guide grooves and pits may be formed on the surface of the substrate. Such guide grooves and pits are preferably provided when the substrate is molded, but can also be provided on the substrate using an ultraviolet curable resin layer. When the guide groove is spiral, the groove pitch is preferably about 0.4 μm or more and 1.2 μm or less, particularly preferably about 0.6 μm or more and 0.9 μm or less.

  The groove depth is an AFM (Atomic Force Microscope) measured value, and is usually 100 nm or more and 200 nm or less. In particular, in order to be able to record in the range of 1X from low speed to 8X at high speed, the groove depth is 150 nm. As mentioned above, it is preferable to set it as about 180 nm or less. When the groove depth is larger than the above lower limit value, the degree of modulation tends to be obtained at a low speed, and when the groove depth is smaller than the above upper limit value, it is easy to ensure a sufficient reflectance. The groove width is a value measured by AFM (atomic force microscope) and is usually 0.20 μm or more and 0.40 μm or less. For high-speed recording applications, the groove width is more preferably 0.28 μm or more and 0.33 μm or less. When the groove width is larger than the above lower limit value, the push-pull signal amplitude is easily obtained. Further, the deformation of the substrate greatly affects the recording signal amplitude. For this reason, if the groove width is made larger than the lower limit, it becomes easy to suppress the influence of thermal interference and obtain good jitter when recording at a high speed of 8 × or more. Furthermore, the recording power margin is widened and the tolerance for fluctuations in the laser power is increased, so that the recording characteristics and recording conditions are improved. When the groove width is smaller than the above upper limit value, thermal interference in the recording mark can be suppressed in low-speed recording such as 1 ×, and a good jitter value can be easily obtained.

  Information such as address information, medium type information, recording pulse conditions, and optimum recording power can be recorded on the optical recording medium to which the present embodiment is applied. As a form for recording such information, for example, the LPP or ADIP format described in the DVD-R and DVD + R standards may be used.

  In the optical recording medium to which the present embodiment is applied, a recording layer containing an azo metal chelate dye having the above-mentioned specific characteristics and structure on a substrate or an undercoat layer as necessary is provided. Form. Such a recording layer containing an azo metal chelate dye has good sensitivity, high reflectance, and a relatively high decomposition temperature (or a weight loss starting temperature in TG-DTA measurement). The recording layer containing the azo metal chelate dye realizes high-speed recording with a single composition.

  Conventional recording layers called high sensitivity are known which use a low decomposition temperature dye having a large absorption coefficient at the recording light wavelength or a decomposition temperature of less than 240 ° C. However, in the former case, it is difficult to obtain a reflectance of 40% or more with the dye alone composition. In the latter case, there is a problem in that deterioration due to reproduction light power and a deterioration in jitter due to crosstalk and thermal interference due to easy spread of recording marks are likely to occur.

  On the other hand, according to the recording layer containing the azo metal chelate dye having the specific characteristics and structure described above, these problems can be solved and high speed recording can be realized. Although the absorption wavelength of the dye used in the recording layer is deep, that is, the absorption coefficient at the recording / reproducing wavelength is high, a high reflectance is obtained. This is probably because the refractive index of the recording layer is high.

  In general, the recording layer of an optical recording medium preferably has a refractive index of 2 to 3 and an extinction coefficient of 0.03 to 0.1 at a recording / reproducing light wavelength of ± 3 nm. In order to perform high-speed recording, the refractive index within this range is preferably as high as possible (for example, 2.5 or more). This is because it is preferable that the refractive index is large, since the optical path difference at the same film thickness can be increased, so that the recording modulation degree can be increased. As for the reflectivity of the disc, the higher the refractive index, the higher the degree of recording modulation with a thinner film thickness. By using this recording layer having a high refractive index, it is possible to reduce the film thickness required for high-speed recording applications of 8X or more, and thermal interference and crosstalk can be suppressed, so that favorable high-speed recording can be realized.

  As a method for forming a recording layer in an optical recording medium to which the present embodiment is applied, a thin film forming method generally performed such as a vacuum deposition method, a sputtering method, a doctor blade method, a casting method, a spin coating method, or an immersion method is used. Is mentioned. The spin coating method is particularly preferable from the viewpoint of mass productivity and cost.

  In the case of film formation by the spin coating method, the rotation speed is preferably 500 to 10,000 rpm. After spin coating, in some cases, treatment such as heating or solvent vapor may be performed. The coating solvent for forming the recording layer by a coating method such as a doctor blade method, a casting method, a spin coating method, or a dipping method may be any solvent that does not attack the substrate and is not particularly limited. Examples of the coating solvent include ketone alcohol solvents such as diacetone alcohol and 3-hydroxy-3-methyl-2-butanone; cellosolv solvents such as methyl cellosolve and ethyl cellosolve; chains such as n-hexane and n-octane. Cyclic hydrocarbon solvents: Cyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, n-butylcyclohexane, t-butylcyclohexane, cyclooctane; tetrafluoropropanol, octafluoropentanol, hexafluorobutanol, etc. Perfluoroalkyl alcohol solvents; hydroxycarboxylic acid ester solvents such as methyl lactate, ethyl lactate and methyl isobutyrate;

  When forming the recording layer, an additive such as a quencher, an ultraviolet absorber, or an adhesive may be mixed with the above dye as necessary. Alternatively, substituents having various effects such as quencher effect and ultraviolet absorption effect can be introduced into the dye. Singlet oxygen quenchers added to improve the light resistance and durability of the recording layer include bisdithiols such as acetylacetonate, bisdithio-α-diketone and bisphenyldithiol, thiocatechol, and salicylaldehyde oxime. And metal complexes such as thiobisphenolate are preferred. Amine compounds are also suitable.

Further, other dyes may be used in combination for improving the recording characteristics. Furthermore, the azo metal chelate dye to which the present embodiment is applied may be used in combination with a dye for low-speed recording so that both high-speed recording and low-speed recording can be achieved. However, the blending ratio is less than 60%, preferably 50% or less, more preferably 40% or less, based on the weight of the azo metal chelate dye. On the other hand, when the low-speed recording dye is used in combination, the blending ratio is usually 0.01% or more. When the blending ratio of the dye for low-speed recording is excessively large, the recording sensitivity necessary for high-speed recording of 8 × or more may not be sufficiently obtained.

  Examples of the dye that can be used in combination include an azo dye compound of the same type as the azo dye compound represented by the formula (1). The dyes that can be used in combination are azo dyes or azo metal chelate dyes, cyanine dyes, squarylium dyes, naphthoquinone dyes, anthraquinone dyes of the same type as the azo metal chelate dyes having the specific characteristics or structures described above. Dye, porphyrin dye, tetrapyraporphyrazine dye, indophenol dye, pyrylium dye, thiopyrylium dye, azurenium dye, triphenylmethane dye, xanthene dye, indanthrene dye, indigo dye, Examples include thioindigo dyes, merocyanine dyes, bispyromethene dyes, thiazine dyes, acridine dyes, oxazine dyes, indoaniline dyes, and other dyes. Examples of the dye thermal decomposition accelerator include metal compounds such as metal anti-knock agents, metallocene compounds, and acetylacetonato metal complexes.

  Furthermore, a binder, a leveling agent, an antifoaming agent, etc. can also be used together as needed. Preferable binders include polyvinyl alcohol, polyvinyl pyrrolidone, nitrocellulose, cellulose acetate, ketone resin, acrylic resin, polystyrene resin, urethane resin, polyvinyl butyral, polycarbonate, polyolefin and the like.

  The film thickness of the recording layer (dye layer) is not particularly limited, but is preferably 50 nm to 300 nm. When the film thickness of the dye layer is larger than the lower limit, the influence of thermal diffusion can be suppressed, and good recording is easy. In addition, since the recording signal is hardly distorted, the signal amplitude can be easily increased. When the film thickness of the dye layer is smaller than the above upper limit value, it is easy to increase the reflectance and to improve the reproduction signal characteristics.

  The groove thickness of the recording layer is usually 90 nm or more and 180 nm or less, preferably 50 nm or more and 90 nm or less, and the film thickness between the grooves is usually 50 nm or more and 100 nm or less, preferably 30 nm or more and 70 nm or less. . When the groove film thickness or the groove film thickness is larger than the above lower limit value, the amplitude of the address information (LPP or ADIP) can be increased, and the occurrence of errors can be easily suppressed. When the groove film thickness or the groove film thickness is smaller than the above upper limit value, it is possible to suppress the influence of heat storage in the recording mark and the increase in crosstalk, and the jitter tends to be good.

  The optical recording medium to which the present embodiment is applied has a reflectivity obtained by combining a recording layer containing an azo metal chelate dye having the specific characteristics or structure described above and a groove shape provided in the substrate. It can be 40% or more. For this reason, for example, a DVD-R that is reproduction-compatible with a DVD-ROM (there are two DVD-Rs and DVD + Rs in the standard, but these are collectively referred to as DVD-R hereinafter) can be realized. The reflectance is measured with a disk player (for example, DVD player, DVD-ROM inspection machine, DVD drive) in which a laser having a wavelength range of 650 nm + 10 nm-5 nm is mounted on the pickup when tracking is performed on the groove of the optical disk. Say the reflectance.

Next, a reflective layer having a thickness of 50 nm to 300 nm is preferably formed on the recording layer. As a material of the reflective layer, a material having a sufficiently high reflectance at the wavelength of the reproduction light, for example, a metal of Au, Al, Ag, Cu, Ti, Cr, Ni, Pt, Ta and Pd is used alone or as an alloy. Is possible. Among these, Au, Al, and Ag have high reflectivity and are suitable as a material for the reflective layer. In particular, Ag and an Ag alloy are preferable because of their high reflectivity and high thermal conductivity. In addition to these metals, the following may be included. For example, Mg, Se, Hf, V, Nb, Ru, W, Mn, Re, Fe, Co, Rh, Ir, Cu, Zn, Cd, Ga, In, Si, Ge, Te, Pb, Po, Sn, Mention may be made of metals such as Bi and metalloids. Among these, those containing Ag as a main component are low in cost, tend to improve reflectance when combined with an azo metal chelate dye, and have a ground when a print receiving layer described later is provided. This is particularly preferable from the viewpoint of obtaining a white and beautiful color. Here, the main component means one having a content of 50% or more. It is also possible to form a multilayer film by alternately stacking a low refractive index thin film and a high refractive index thin film using a material other than metal, and use it as a reflective layer.

  Examples of the method for forming the reflective layer include sputtering, ion plating, chemical vapor deposition, and vacuum vapor deposition. In addition, a known inorganic or organic intermediate layer or adhesive layer may be provided on the substrate or under the reflective layer in order to improve reflectivity, improve recording characteristics, and improve adhesion.

The material of the protective layer formed on the reflective layer is not particularly limited as long as it protects the reflective layer from external force. For example, examples of the organic substance include a thermoplastic resin, a thermosetting resin, an electron beam curable resin, and a UV curable resin. Examples of the inorganic substance include SiO ₂ , SiN ₄ , MgF ₂ , SnO _{2 and the} like. A thermoplastic resin, a thermosetting resin, or the like can be formed by dissolving in an appropriate solvent, applying a coating solution, and drying. The UV curable resin can be formed by preparing a coating solution as it is or by dissolving it in a suitable solvent, and then applying the coating solution and curing it by irradiating with UV light. Examples of the UV curable resin include acrylate resins such as urethane acrylate, epoxy acrylate, and polyester acrylate. These materials may be used alone or in combination, and may be used not only as a single layer but also as a multilayer film.

  As a method for forming the protective layer, a coating method such as a spin coating method and a casting method, a sputtering method, a chemical vapor deposition method, and the like are used as in the recording layer. Among these, a spin coating method is preferable. The thickness of the protective layer is usually in the range of 0.1 μm or more and 100 μm or less. In the present embodiment, the thickness of the protective layer is preferably 3 μm or more, more preferably 5 μm or more, and preferably 30 μm or less, more preferably 20 μm or less.

  In addition, this Embodiment is not limited to said aspect, A various deformation | transformation can be carried out. For example, the optical recording medium may have two or more recording layers. Alternatively, a so-called dummy substrate having no groove on the reflective layer surface may be bonded, or two optical recording media facing each other with the reflective layer surfaces facing each other may be used. An ultraviolet curable resin, an inorganic thin film, or the like may be formed on the mirror surface side of the substrate in order to protect the surface or prevent adhesion of dust and the like. Furthermore, a print receiving layer can be further formed on a protective layer provided on the reflective layer or on a substrate bonded to the reflective layer surface.

  Recording on the optical recording medium obtained as described above is usually performed by irradiating a recording layer provided on both sides or one side of the substrate with laser light. In general, thermal deformation of the recording layer such as decomposition, heat generation, and melting due to absorption of laser light energy occurs in the portion irradiated with the laser light. The recorded information is normally reproduced by reading the difference in reflectance between a portion where thermal deformation has occurred and a portion where it has not occurred due to laser light.

There is no particular limitation on the laser used for recording / reproduction, but for example, a dye laser capable of selecting a wavelength in a wide range in the visible region, a helium neon laser having a wavelength of 633 nm, and a recently developed high output around 680, 660, and 635 nm. A semiconductor laser, a blue laser near 400 nm, a harmonic conversion YAG laser having a wavelength of 532 nm, and the like can be mentioned. Among these, a semiconductor laser is preferable in terms of lightness, ease of handling, compactness, cost, and the like. The optical recording medium to which the present embodiment is applied can perform high-density recording and reproduction at one wavelength or a plurality of wavelengths selected from these.

Hereinafter, the present embodiment will be specifically described by way of examples. However, this embodiment does not limit the present embodiment unless it exceeds the gist.
(Example 1)
(A) Compound production example (diazo coupling)
1.15 g of 2-amino-1,3,4-thiadiazole (Structural Formula 1a) is dissolved in 13.7 g of acetic acid, 11.8 g of phosphoric acid and 4.7 g of sulfuric acid, cooled to 5 ° C. or lower and 43% nitrosylsulfuric acid. 3.4 g was added dropwise to prepare a diazo solution of 2-amino-1,3,4-thiadiazole. Next, the diazo liquid obtained previously was added dropwise to a solution of 2.2 g of the compound represented by the following structural formula 1b and 44 ml of methanol under the condition of 5 ° C. or lower and stirred for 2 hours. Subsequently, after neutralizing with 28% aqueous ammonia, the precipitated crystals were filtered and purified to obtain 1.3 g of an azo compound represented by the following structural formula 1c.

(Mounting)
1.3 g of the azo compound represented by the structural formula 1c was dissolved in 52 ml of tetrahydrofuran, and insoluble matters were separated by filtration. Next, 0.47 g of nickel acetate tetrahydrate was dissolved in 7 ml of methanol, and this was added dropwise to a THF solution of the azo compound represented by the structural formula 1c at room temperature. Further, 72 ml of water was added, and the precipitated crystals were filtered, purified and dried to obtain 0.8 g of an azo nickel chelate dye. The maximum absorption wavelength of this azonickel chelate dye in chloroform was 588 nm, the Gram extinction coefficient was 141 L / gcm, and the absorption maximum wavelength of the coating film was 607 nm.

(B) Recording example A 1.7 wt% octafluoropentanol (hereinafter referred to as OFP) solution of the azonickel chelate dye thus prepared was guided with a track pitch of 0.74 μm, a groove depth of 160 nm, and a groove width of 0.31 μm. It spin-coated on the transparent polycarbonate substrate in which the groove | channel was formed, and was dried at 100 degreeC for 20 minutes. This recording layer had a groove thickness of 55 nm and a groove thickness of 85 nm. On this recording layer, silver was sputtered with 120 nm, UV-cured resin was spin-coated with 3 μm, and a dummy substrate (same transparent substrate) having no groove was bonded after spin-coating the adhesive. This disk was subjected to 8X (28 m / s linear velocity) recording under a recording pulse condition conforming to the DVD-R standard version 2.01 using a 660 nm semiconductor laser evaluator (NA = 0.65). Thereafter, reproduction was performed at 1X (3.5 m / s linear velocity). As a result, the 8X recording sensitivity was 26.8 mW, and the jitter (hereinafter referred to as jitter with respect to the clock 1T = 38.2 ns) was good at 8.2%. It was. When recorded on this disk at 1 ×, the recording sensitivity was 6.2 mW, the recording modulation degree was 55%, and the jitter was 7.8%. The reflectivity of the above-mentioned disk measured with a DVD-ROM inspection machine (ILMA220, wavelength: 647 nm, manufactured by Shibasoku) was as good as 47%.

Although the upper limit power of the recording laser near 660 nm has been increased gradually, from the viewpoint of mass production, beam shaping (power is reduced when the beam is shaped better), and price. The recording sensitivity at 8X is preferably around 28 mW. Also, the jitter is less than 9%, preferably less than 8%.

(Example 2)
(A) Compound Production Example Under the same conditions as in Example 1, using the compounds represented by the following structural formula 2a and the following structural formula 2b as starting materials, the azo compound 2c represented by the following structural formula 2c and nickel An azonickel chelate dye was prepared. The maximum absorption wavelength of this azonickel chelate dye in chloroform was 589 nm, the Gram extinction coefficient was 139 L / gcm, and the absorption maximum of the coating film was 609 nm.

(B) Recording example The same as in Example 1 except that the dye was changed to the dye having the above structure and the film thickness was reduced to 75% of Example 1 (inter-groove film thickness was about 41 nm, groove film thickness was about 64 nm). Thus, a disk was manufactured. Recording and reproduction of this disk were performed in the same manner as in Example 1. The 8X recording sensitivity was 22 mW, and the jitter was as good as 7.7%. The reflectivity was 46%.

(Example 3)
(A) Compound Production Example Under the same conditions as in Example 1, an azo compound represented by the following structural formula 3c was prepared using the following structural formula 3a and the following structural formula 3b as starting materials. An azonickel chelate dye with nickel was obtained. The maximum absorption wavelength of this azonickel chelate dye in chloroform was 588 nm, the Gram extinction coefficient was 143 L / gcm, and the absorption maximum wavelength of the coating film was 607 nm.

(B) Recording Example A disk was produced in the same manner as in Example 2 except that the dye was changed to a dye having the above structure. Recording and reproduction of this disc was performed in the same manner as in Example 2. As a result, the 8X recording sensitivity was 24.8 mW, the jitter was 7.3%, and the reflectance was 47%.

Example 4
(A) Compound Production Example Under the same conditions as in Example 1, an azo compound represented by the following structural formula 4c was prepared using the following structural formula 4a and the following structural formula 4b as starting materials, and the azo compound 4c An azo nickel chelate dye composed of nickel was obtained. The maximum absorption wavelength of this azonickel chelate dye in chloroform was 587 nm, the Gram extinction coefficient was 139 L / gcm, and the absorption maximum wavelength of the coating film was 610 nm.

(B) Recording Example A disk was produced in the same manner as in Example 2 except that the dye was changed to a dye having the above structure. Recording and reproduction of this disc was performed in the same manner as in Example 2. As a result, the 8X recording sensitivity was 23.6 mW, the jitter was 7.2%, and the reflectance was 46%.

(Example 5)
(A) Compound Production Example Under the same conditions as in Example 1, an azo compound represented by the following structural formula 5c was prepared using the following structural formula 5a and the following structural formula 5b as starting materials, and the azo compound 5c An azo nickel chelate dye composed of nickel was obtained. The maximum absorption wavelength of this azonickel chelate dye in chloroform was 587 nm, the Gram extinction coefficient was 139 L / gcm, and the absorption maximum wavelength of the coating film was 608 nm.

(B) Recording Example A disk was produced in the same manner as in Example 2 except that the dye was changed to a dye having the above structure. Recording and reproduction of this disc was performed in the same manner as in Example 2. As a result, the 8X recording sensitivity was 23.6 mW, the jitter was 7.4%, and the reflectance was 48%.

(Example 6)
(A) Compound Production Example Under the same conditions as in Example 1, an azo compound represented by the following structural formula 6c was prepared using the following structural formula 6a and the following structural formula 6b as starting materials, and the azo compound 6c An azo nickel chelate dye composed of nickel was obtained. The maximum absorption wavelength of this azonickel chelate dye in chloroform was 590 nm, the Gram extinction coefficient was 140 L / gcm, and the absorption wavelength of the coating film was 608 nm.

(B) Recording Example A disk was produced in the same manner as in Example 2 except that the dye was changed to a dye having the above structure. Recording and reproduction of this disk were performed in the same manner as in Example 2. As a result, the recording sensitivity of 8X was 25 mW, the jitter was 7.4%, and the reflectance was 47%.

(Example 7)
(A) Compound Production Example Under the same conditions as in Example 1, an azo compound represented by the following structural formula 7c was prepared using the following structural formula 7a and the following structural formula 7b as starting materials, and the azo compound 7c and An azo nickel chelate dye composed of nickel was obtained. The maximum absorption wavelength of this azonickel chelate dye in chloroform was 590 nm, the Gram extinction coefficient was 137 L / gcm, and the absorption maximum wavelength of the coating film was 609 nm.

(B) Recording Example A disk was produced in the same manner as in Example 2 except that the dye was changed to a dye having the above structure. Recording and reproduction of this disc was performed in the same manner as in Example 2. As a result, the 8X recording sensitivity was 25.8 mW, the jitter was 7.6%, and the reflectance was 47%.

(Example 8)
(A) Compound Production Example Under the same conditions as in Example 1, an azo compound represented by the following structural formula 8c was prepared using the following structural formula 8a and the following structural formula 8b as starting materials, and the azo compound 8c An azo nickel chelate dye composed of nickel was obtained. The maximum absorption wavelength of this azonickel chelate dye in chloroform was 595 nm, the Gram extinction coefficient was 137 L / gcm, and the absorption maximum wavelength of the coating film was 613 nm.

(B) Recording Example A disk was produced in the same manner as in Example 2 except that the dye was changed to a dye having the above structure. Recording and reproduction of this disc was performed in the same manner as in Example 2. As a result, the 8X recording sensitivity was 22.8 mW, the jitter was 7.8%, and the reflectance was 48%. Incidentally, the recording modulation degree in 1X recording of the disks of Examples 2 to 8 was 40-50%.

(Comparative Example 1)
(A) Compound Production Example Under the same conditions as in Example 1, a nickel chelate dye with azo compound 101c was obtained.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 580 nm, the Gram extinction coefficient was 142 L / gcm, and the absorption maximum wavelength of the coating film was 598 nm.

(B) Recording Example A disk was produced in the same manner as in Example 2 except that the dye was changed to the above dye. Recording and reproduction of this disc was performed in the same manner as in Example 2. As a result, even though the laser light intensity was increased to 28 mW, even 4X recording was not possible because the recording sensitivity was too bad (jitter> 14%). The reflectivity of this disk was 58% as measured with a DVD-ROM inspection machine.

(Comparative Example 2)
(A) Compound Production Example Under the same conditions as in Example 1, a nickel chelate dye with the azo compound 102c was obtained.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 585 nm, the Gram extinction coefficient was 125 L / gcm, and the coating film absorption maximum wavelength was 604 nm.

(B) Recording Example A disk was produced in the same manner as in Comparative Example 1 except that the dye was changed to the dye having the above structural formula. Recording and reproduction of this disc was performed in the same manner as in Example 2. As a result, even 4X recording did not have sufficient recording sensitivity, the recording sensitivity was still insufficient at 48 mW, and the jitter was not as good as 13%. The reflectivity of this disk measured with a DVD-ROM inspection machine was 48%.

Example 9
The azo nickel chelate dye prepared in Example 4 and the nickel chelate dye prepared in Comparative Example 2 were mixed at a weight ratio of 60:40 to prepare an OFP solution of 1.9% by weight of the mixed dye with respect to the solvent. . Next, this solution is spin-coated on a polycarbonate substrate having a guide groove having a track pitch of 0.74 μm, a groove depth of 163 nm, and a groove width of 0.32 μm, and a recording layer having a groove thickness of 60 nm and a groove thickness of 90 nm is recorded. Formed. Others were made in the same manner as in Example 2, recorded at 8X, and played back at 1X. As a result, the recording sensitivity of 8X recording was 25.4 mW, the jitter was 7.3%, and the reflectance was 49%. In addition, 1X recording has a recording sensitivity of 6.0 mW, a jitter of 7.1%, and a recording modulation degree of 61%. Even in 1X recording, good recording characteristics were obtained. That is, the disk characteristics satisfying the DVD-R standard document at 1X or 8X were shown.

(Example 10)
A disk was produced under the same conditions and method as in Example 9, except that the dye was changed to the dye prepared in Example 2 and the dye prepared in Comparative Example 1. Recording and reproduction were performed in the same manner as in Example 9. As a result, the 8X recording sensitivity is 26 mW, the jitter is 7.2%, and the reflectance is 49%. The 1X recording sensitivity is 6.2 mW, the jitter is 7.1%, and the recording modulation degree is 60%. Obtained.

(Example 11)
A disk was produced under the same conditions and method as in Example 9, except that the dye was changed to the dye prepared in Example 5 and the dye prepared in Comparative Example 1 (weight ratio 60:40). Recording and reproduction were performed in the same manner as in Example 9. As a result, the 8X recording sensitivity is 26.2 mW, the jitter is 7.3%, the reflectance is 50%, the 1X recording sensitivity is 6.2 mW, the jitter is 7.1%, and the recording modulation degree is 61%. was gotten.

(Example 12)
A disk was produced under the same conditions and method as in Example 9, except that the dye was changed to a mixed dye having a weight ratio of 50:50 of the dye prepared in Example 1 and the dye prepared in Comparative Example 1. Recording and reproduction were performed in the same manner as in Example 9. As a result, although 8X recording sensitivity was slightly insufficient at 28 mW, jitter was 7.5% and reflectance was 52%, 1X recording sensitivity was 6.4 mW, jitter was 7.1%, and recording modulation was 61%. It was.

(Comparative Example 3)
(A) Compound Production Example Under the same conditions as in Example 1, a nickel chelate dye with the azo compound 105c was obtained. The maximum absorption wavelength of this azonickel chelate dye in chloroform was 589 nm, the Gram extinction coefficient was 109 L / gcm, and the absorption maximum wavelength of the coating film was 607 nm.

(B) Recording Example A disk was produced in the same manner as in Example 2 except that the dye was changed to the dye having the above structural formula. Recording and reproduction were performed in the same manner as in Example 2. As a result, the recording sensitivity was slightly insufficient at 28 mW, and the jitter was not as good as 9.3%. When recording was performed under the same recording conditions as in Example 9 capable of increasing the recording sensitivity, the 8X recording sensitivity was 25 mW, but the thermal interference was too great, and a good recording characteristic of 11% jitter could not be obtained. It was. The reflectivity of this disk measured with a DVD-ROM inspection machine was 46%.

(Comparative Example 4)
(A) Compound Production Example Under the same conditions as in Example 1, a nickel chelate dye with the azo compound 106c was obtained. The maximum absorption wavelength of this azonickel chelate dye in chloroform was 585 nm, the gram extinction coefficient was 132 L / gcm, and the absorption maximum wavelength of the coating film was 609 nm.

(B) Recording Example A disk was produced in the same manner as in Example 2 except that the dye was changed to the dye having the above structural formula. Recording and reproduction were performed in the same manner as in Example 2. The recording sensitivity of 8X was as good as 22 mW, but because of the large thermal interference, good recording characteristics could be obtained only with a power 1 mW lower than the recording sensitivity. The reflectivity was 39%, which was not preferable for DVD-R playback operation.

(Comparative Example 5)
(A) Compound Production Example A nickel chelate dye with the azo compound 107c was obtained under the same conditions as in Example 1. The maximum absorption wavelength of this azonickel chelate dye in chloroform was 589 nm, the Gram extinction coefficient was 91 L / gcm, and the absorption maximum wavelength of the coating film was 601 nm.

(B) Recording Example A disk was produced in the same manner as in Example 2 except that the dye was changed to the dye having the above structural formula. Recording and reproduction were performed under the same recording conditions as in Comparative Example 1. As a result, even with 28 mW, even 4 × recording had insufficient recording sensitivity, and good recording could not be performed. The reflectivity of this disk measured with a DVD-ROM inspection machine was 46%.

(Comparative Example 6)
(A) Compound Production Example 13.99 g of 1,2,3,4-tetrahydroquinoline and 14.52 g of potassium carbonate were dissolved in 350 ml of methanol and kept at 45 to 50 ° C. with stirring, and 25.54 g of dimethyl sulfate was added thereto. It was dripped. Subsequently, the mixture was stirred at 45 to 50 ° C. for 3 hours and then left overnight. To the reaction solution, 350 ml of toluene and 350 ml of water were added to perform toluene extraction. The extracted toluene solution was dried over anhydrous sodium sulfate, and then toluene was distilled off to obtain a brown liquid. This was subjected to column purification to obtain 12.9 g of a pale yellow solution represented by the following structural formula (e).

  12.9 g of the compound represented by the structural formula (e) was dropped into 230 g of concentrated sulfuric acid cooled to 0 to 5 ° C. while maintaining the temperature at 0 to 5 ° C. Subsequently, a mixed solution of 36 g of concentrated sulfuric acid and 9.0 g of concentrated nitric acid was added dropwise while maintaining the temperature at 0 to 5 ° C. After completion of the dropwise addition, the mixture was returned to room temperature and stirred for 2 hours. The reaction solution was poured into 300 ml of ice water, and a 50% aqueous sodium hydroxide solution was added to pH 9 while cooling. After stirring for 1 hour, the precipitated crystals were separated by filtration and dried to obtain 12.4 g of red crystals represented by the following structural formula (f).

  31.4 g of iron powder is suspended in 183 ml of DMF-water (2: 1) and heated to 85-90 ° C. with stirring, and 6.7 ml of hydrochloric acid and 91.5 ml of DMF-water (2: 1) are added thereto. The mixed solution was added dropwise. Subsequently, 183 ml of a DMF solution of 12.0 g of the compound represented by the structural formula (f) was added dropwise over 15 minutes while maintaining the temperature at 85 to 95 ° C. The mixture was stirred at 80 to 90 ° C. for 20 minutes, and then allowed to cool, 6.39 g of sodium hydrogen carbonate was added and stirred for 10 minutes. The solution was filtered to remove iron powder, and the filtrate was poured into 500 ml of ice water and extracted with toluene. After drying over anhydrous sodium sulfate, toluene was distilled off to obtain 5.47 g of a brown liquid represented by the following structural formula (g).

  Under a nitrogen stream, 9.31 g of trifluoromethanesulfonic anhydride was kept at 20 ° C. or lower while stirring, and a solution of 5.47 g of the compound represented by the structural formula (g) in 40 ml of toluene was added dropwise. Subsequently, the mixture was stirred at 10 to 15 ° C. for 4 hours and then left overnight. After adding 2 ml of water to the reaction solution at 10 to 25 ° C. and stirring for 1 hour, the precipitated solid was filtered off. The collected solid was dissolved in ethyl acetate, 150 ml of water was added, and the mixture was extracted with ethyl acetate. After drying over anhydrous sodium sulfate, ethyl acetate was distilled off to obtain 6.87 g of a dark brown liquid represented by the following structural formula (h).

  0.58 g of 2-amino-5-methyl-1,3,4-thiadiazole represented by the above structural formula (i) is dissolved in 5 ml of acetic acid and 3 ml of propionic acid, and 1 ml of sulfuric acid is added dropwise at 0 to 5 ° C. Diazotization was performed by adding 1.78 g of 43% nitrosylsulfuric acid at -5 ° C. The obtained diazo solution was added dropwise at 0 to 5 ° C. to a solution prepared by dissolving 1.77 g of the compound represented by the structural formula (h), 0.2 g of urea and 2.0 g of sodium acetate in 20 ml of methanol, and the mixture was stirred for 3 hours. Then left overnight. The precipitated crystals were collected by filtration and dried to obtain 1.44 g of red crystals represented by the following structural formula (j).

1.30 g of the azo compound represented by the structural formula (j) obtained as described above was dissolved in 50 ml of THF, and a solution of 0.46 g of nickel acetate tetrahydrate in 6 ml of methanol was added at room temperature. Stir for hours and add 50 ml of water. The precipitated crystals were separated by filtration, washed with water and dried to obtain 0.59 g of nickel chelate compound. Λmax (in chloroform) of this compound was 591 nm (ε = 9.9 × 10 ⁴ ), the gram extinction coefficient was 113 L / gcm, and the absorption maximum wavelength of the coating film was 613 nm.

(Measurement of OD2 / OD1)
After 20 mg of the dyes of Examples 1 to 8 and Comparative Examples 1 to 6 were contained in 2 g of octafluoropentanol (OFP), ultrasonic dispersion was performed at 50 ° C. to 55 ° C. for 60 minutes to obtain Solution A. Obtained. The solution A was cooled to room temperature (25 ± 5 ° C.) and then filtered through a 0.2 μm filter manufactured by Millipore to obtain a solution B. The solution B was spin-coated at a rotation speed of 800 pm on a polycarbonate substrate having a groove depth of 170 nm, a groove width of 500 nm, and a track pitch of 1600 nm and a thickness of 1.2 mm. The film of the dye-single composition thus obtained was held in an air blow dryer at 80 ° C. for 5 minutes, and then left in the room to cool to room temperature (production of coated substrate A).
The absorption spectrum of the coated substrate A was measured. In measuring the absorption spectrum, the coated substrate A was cut into a fan shape to obtain a measurement sample. The reference sample was air. And it measured using Hitachi, Ltd. U-3300. The measurement conditions were a wavelength scan speed of 300 nm / min. In the absorbance measurement (Absorbance) mode with a sampling period of 0.5 nm.
In FIG. 1, the absorption spectrum of the coating substrate A using the pigment | dye of Example 1 is shown. Table 1 shows the wavelength and absorbance of OD1 and OD2 of each coated substrate A, and the value of OD2 / OD1.

Moreover, in FIG. 3, the value of OD2 / OD1 of Example 1- Example 8 and Comparative Example 1- Comparative Example 6 is shown. From the results shown in FIG. 3, a boundary of 1.25 is seen between Examples 1 to 8 and Comparative Examples 1 to 6.
Furthermore, in FIG. 4, the absorption maximum wavelength (wavelength indicating OD2) of the coated substrate A produced in Examples 1 to 8 and Comparative Examples 1 to 5 is measured with a DVD-ROM inspection machine (647 nm). The measurement results of the reflectance of each disk with a radius of 40 mm are shown. From the results shown in FIG. 4, in the disks of Comparative Examples 1 to 5, the reflectance tends to decrease as the wavelength of the absorption maximum of the film becomes longer, as shown by the regression line in FIG. In the dyes of Comparative Examples 1 to 5, it tends to be difficult to obtain a reflectance of 45% or more, which is the standard for DVD reproduction, with a dye having an absorption maximum at a wavelength longer than 605 nm. On the other hand, it can be seen that the disks using the dyes of Examples 1 to 8 can ensure a high reflectance even with a dye having an absorption maximum in the vicinity of 610 nm.

(Measurement of reference data)
0.06 g of an azo metal chelate dye having the following structural formulas ((S-1) to (S-6)) was added to 5 g of OFP solvent, respectively, and ultrasonically dispersed at 50 ° C. for 60 minutes. Then, this solution was left to cool to room temperature. The solution was filtered through a 0.2 μm Millipore filter, and the resulting solution was placed on a mirror surface replica (polycarbonate substrate without guide grooves) so as to cover approximately half of the surface of the board and spin coated. After drying, a reflective layer was sputtered onto a part of the spin-coated recording layer. The level difference between the uncoated portion covered with the reflective layer and the recording layer covered with the reflective layer was measured with a three-dimensional surface roughness meter (ZYGO: Maxim5800 manufactured by Canon Inc.) to determine the film thickness. Furthermore, in a recording layer without a reflective layer, light from 580 nm to 650 nm is irradiated with an automatic wavelength scanning ellipsometer (MEL-30S type) manufactured by JASCO Corporation, and the reflectance and phase difference are measured in a multiple incident angle measurement mode. Was measured. Then, a combination of the refractive index n and the extinction coefficient k having a good focusing condition was obtained at each wavelength with reference to the above-mentioned film thickness. Of the refractive indexes of the respective wavelengths obtained in this manner, the refractive index n for obtaining the maximum value was used.

On the other hand, for each of the dyes (S-1) to (S-6), a coated substrate A formed with each dye was prepared in the same manner as in the above “Measurement of OD2 / OD1,” and the absorption spectrum was measured. Then, OD2 / OD1 was calculated.
Table 2 and FIG. 2 show OD2 / OD1 and n (the maximum value of the refractive index) obtained as described above. The data points are values of the dyes (S-1) to (S-6) from the left side (from the smaller OD2 / OD1 toward the larger one).

(Example 13)
(A) Compound Production Example The compound was produced using the following structural formula 13a and the following structural formula 13b as starting materials under the same conditions as in Example 1 to obtain a nickel chelate dye with the azo compound 13c.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 588 nm, the gram extinction coefficient was 130 L / gcm, and the absorption maximum of the coating film was 604 nm.

(Example 14)
(A) Compound Production Example The compound was produced using the following structural formula 14a and the following structural formula 14b as starting materials under the same conditions as in Example 1 to obtain a nickel chelate dye with the azo compound 14c.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 591 nm, the Gram extinction coefficient was 133 L / gcm, and the absorption maximum wavelength of the coating film was 607 nm.

(Example 15)
(A) Compound Production Example Under the same conditions as in Example 1, the starting material was produced using the following structural formula 15a and the following structural formula 15b to obtain a nickel chelate dye with the azo compound 15c.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 588 nm, the Gram extinction coefficient was 138 L / gcm, and the absorption maximum wavelength of the coating film was 608 nm.

(Example 16)
(A) Compound Production Example Under the same conditions as in Example 1, the starting material was produced using the following structural formula 16a and the following structural formula 16b to obtain a nickel chelate dye with the azo compound 16c.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 587 nm, the Gram extinction coefficient was 140 L / gcm, and the absorption maximum wavelength of the coating film was 607 nm.

(Example 17)
(A) Compound Production Example Under the same conditions as in Example 1, the starting material was produced using the following structural formula 17a and the following structural formula 17b to obtain a nickel chelate dye with the azo compound 17c.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 596 nm, the Gram extinction coefficient was 150 L / gcm, and the absorption maximum wavelength of the coating film was 613 nm.

(Example 18)
(A) Compound Production Example The compound was produced using the following structural formula 18a and the following structural formula 18b as starting materials under the same conditions as in Example 1 to obtain a nickel chelate dye with the azo compound 18c.
The maximum absorption wavelength of this azonickel chelate dye in chloroform was 598 nm, the Gram extinction coefficient was 139 L / gcm, and the absorption wavelength of the coating film was 613 nm.

In the dyes of Examples 13 to 18, the coated substrate A formed with each dye was prepared in the same manner as in the above “Measurement of OD2 / OD1,” and the absorption spectrum was measured. Table 3 shows the calculated OD2 / OD1.
As described in Table 3, in any of Examples 13 to 18, OD2 / OD1 was larger than 1.25, which was a favorable result.

According to the present invention, an azo metal chelate dye capable of high-speed recording and an optical recording medium capable of high-speed recording using the azo metal chelate dye are provided.
In addition, this application is based on the Japanese application (Japanese Patent Application No. 2003-319766) for which it applied on September 11, 2003, The whole is used by reference.

2 is an absorption spectrum of a coated substrate A using the dye of Example 1. It is a graph which shows the relationship between OD2 / OD1 and the refractive index in the pigment | dye film | membrane of pigment | dye (S-1)-(S-6). It is the value of OD2 / OD1 of Examples 1 to 8 and Comparative Examples 1 to 6. The absorption maximum wavelength (wavelength indicating OD2) of the coated substrate A produced in Examples 1 to 8 and Comparative Examples 1 to 5, and a radius of 40 mm of each disk measured with a DVD-ROM inspection machine (647 nm). It is a measurement result of reflectance. It is a figure which shows the example which has an absorption shoulder in the absorption spectrum of the pigment | dye film | membrane of an azo metal chelate pigment | dye.

Claims (7)

An azo metal chelate dye comprising an azo dye compound and a metal, wherein OD2 / OD1 measured by the following measurement method is greater than 1.25.
(Measurement method of OD2 / OD1)
(1) After 20 mg of an azo metal chelate dye is contained in 2 g of an octafluoropentanol (OFP) solvent, ultrasonic dispersion is performed at 50 ° C. to 55 ° C. for 60 minutes to obtain a solution A. Solution A is cooled to room temperature (25 ± 5 ° C.) to obtain solution B.
(2) The solution B is spin-coated on a polycarbonate substrate at a rotation speed of 800 rpm. Then, the substrate coated with the solution B is held at 80 ° C. for 5 minutes. The substrate thus coated with the solution B is referred to as a coated substrate A.
(3) The absorption spectrum of the coated substrate A at 400 nm to 800 nm is measured.
(4) Among the absorption peaks observed at 500 nm to 700 nm in the obtained absorption spectrum, the absorbance of the absorption peak on the long wavelength side of the absorption peak having the largest absorbance and the absorbance peak next to that is OD2, OD2 / OD1 is calculated with the absorbance at the absorption peak on the short wavelength side as OD1. The azo metal chelate dye according to claim 1, comprising an azo dye compound represented by the following general formula (1) and a metal.

(In the formula, R ₁ is a hydrogen atom or an ester group represented by CO ₂ R ₃ , and R ₃ is a linear or branched alkyl group which may be substituted, or a cycloalkyl group which may be substituted. R ₂ is a linear or branched alkyl group which may be substituted, at least one of X ₁ or X ₂ is an NHSO ₂ Y group, and Y is substituted with at least two fluorine atoms. R _{4 and} R ₅ are each independently a hydrogen atom or an optionally substituted linear or branched alkyl group, and R _6, R _7, R ₈ and R ₉ is independently a hydrogen atom or an alkyl group having 1 to 2 carbon atoms.)   The azo metal chelate dye according to claim 1 or 2, wherein the metal is at least one selected from the group consisting of Ni, Co, Cu, and Pd. An optical recording medium having a recording layer on which information is recorded and / or reproduced by irradiated light on a substrate,
An optical recording characterized in that the recording layer contains an azo metal chelate dye comprising an azo dye compound and a metal, and OD2 / OD1 of the azo metal chelate dye measured by the following measurement method is larger than 1.25. Medium.
(Measurement method of OD2 / OD1)
(1) After 20 mg of an azo metal chelate dye is contained in 2 g of an octafluoropentanol (OFP) solvent, ultrasonic dispersion is performed at 50 ° C. to 55 ° C. for 60 minutes to obtain a solution A. Solution A is cooled to room temperature (25 ± 5 ° C.) to obtain solution B.
(2) The solution B is spin-coated on a polycarbonate substrate at a rotation speed of 800 rpm. Then, the substrate coated with the solution B is held at 80 ° C. for 5 minutes. The substrate thus coated with the solution B is referred to as a coated substrate A.
(3) The absorption spectrum of the coated substrate A at 400 nm to 800 nm is measured.
(4) Among the absorption peaks observed at 500 nm to 700 nm in the obtained absorption spectrum, the absorbance of the absorption peak on the long wavelength side of the absorption peak having the largest absorbance and the absorbance peak next to that is OD2, OD2 / OD1 is calculated with the absorbance at the absorption peak on the short wavelength side as OD1. The optical recording medium according to claim 4, wherein the azo metal chelate dye contains an azo metal chelate dye composed of an azo dye compound represented by the following general formula (1) and a metal.

(In the formula, R ₁ is a hydrogen atom or an ester group represented by CO ₂ R ₃ , and R ₃ is a linear or branched alkyl group which may be substituted, or a cycloalkyl group which may be substituted. R ₂ is a linear or branched alkyl group which may be substituted, at least one of X ₁ or X ₂ is an NHSO ₂ Y group, and Y is substituted with at least two fluorine atoms. R _{4 and} R ₅ are each independently a hydrogen atom or an optionally substituted linear or branched alkyl group, and R _6, R _7, R ₈ and R ₉ is independently a hydrogen atom or an alkyl group having 1 to 2 carbon atoms.)   6. The optical recording medium according to claim 4, wherein the metal is at least one selected from the group consisting of Ni, Co, Cu, and Pd.   The optical recording medium according to claim 4, wherein the azo metal chelate dye has an absorption maximum at a wavelength of 650 nm or less with respect to the irradiated light.

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