JP2007015181A - Optical recording medium, pigment for its recording layer and recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pigment for forming an aminocatechol-metal complex compound-based recording layer, which has excellent solubility to a solvent, is free from the generation of an odor ensuing from heat decomposition, can be easily formulated, can congenially meet optical recording by a blue laser light when used for forming a recording layer of an optical recording medium, and shows high light resistance, heat resistance and heat/moisture resistance. <P>SOLUTION: This pigment for forming a recording layer of the optical recording medium comprises a compound represented by formula [I]. In the formula [I], a ring A and a ring A' are each independently an aromatic hydrocarbon ring which may have a substituent group or a heteroaromatic ring which may have a substituent group, Q and Q' are each independently an aromatic hydrocarbon ring group which may have a substituent group or an aromatic heterocyclic group which may have a substituent group, wherein Q and Q' may be connected with each other directly or through a linking roup. M is a metal atom. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an aminocatechol metal complex compound dye used for forming a recording layer of an optical recording medium. In particular, the present invention relates to a dye used for an optical recording medium compatible with blue laser light. The present invention also relates to an optical recording medium having a recording layer using such a dye and a recording method thereof.

  In recent years, since it is possible to record / store / reproduce information at a high density, development of an optical recording medium using a laser beam, particularly an optical disk, has been underway. Among the optical disks, a writable compact disk (CD-R) is recently attracting attention. The CD-R usually has a structure in which a recording layer mainly composed of a dye, a metal reflective film, and a protective film are sequentially laminated on a circular plastic substrate having guide grooves. Information is recorded on the CD-R by irradiating a laser beam and absorbing the irradiation energy in the recording layer, so that heat such as decomposition, evaporation, dissolution, etc. is generated in the recording layer, reflecting layer or substrate of the laser beam irradiation portion. This is performed by a method of generating a general deformation (heat mode), a method of reversibly changing the structure of the dye contained in the recording layer of the laser light irradiated portion (photon mode), or the like. The recorded information is reproduced by reading the difference in reflectance with respect to the laser beam between the portion where thermal deformation or dye structure change due to laser light irradiation occurs and the portion where it does not occur. Therefore, it is necessary for the recording layer of the optical recording medium to efficiently absorb the energy of the laser beam, and a laser beam absorbing dye is generally used for the recording layer.

  An optical recording medium using an organic dye as a laser light absorbing dye can form a recording layer by a simple method of applying an organic dye solution, and is expected to become increasingly popular as an inexpensive optical recording medium in the future. .

  Also, in recent years, in order to increase the recording density, the wavelength of laser light used for recording has been shortened from a wavelength centered on the conventional semiconductor laser emission wavelength of 780 nm to a blue light region of about 405 nm or less. Is being considered.

  As compounds that have been attracting attention as dyes for optical recording media using lasers in the blue light region, porphyrin compounds (Patent Documents 1 and 2, etc.), cyanine compounds (Patent Documents 3, 4 etc.), polyenes Compounds (Patent Documents 5 and 6 etc.), azo compounds (Patent Documents 7 and 8 etc.), coumarin compounds (Patent Documents 9 and 10 etc.), naphthalocyanine compounds (Patent Document 11 etc.), styryl compounds (Patents) Documents 12, 13, etc.) and quinone compounds (Patent Document 14, etc.).

  However, porphyrin compounds have a highly symmetric structure and have a hard skeleton, and therefore generally have high crystallinity and low solubility in solvents. Further, agglomeration (precipitation) may occur after a solution dissolved in a solvent is applied to the substrate to form a recording layer. Cyanine compounds, polyene compounds, coumarin compounds, styryl compounds, quinone compounds, and the like are relatively weak in light resistance, and an additive such as a quencher may be required for practical use. An azo compound has a limit in adjusting the absorption maximum in the wavelength region of the blue laser. In addition, naphthalocyanine compounds have low solubility, and there is a limit to wavelength adjustment for absorption maximum.

  Patent Document 15 proposes a benzenedithiol complex-based compound typified by the following compound as a compound that has good solubility in a solvent, is stable in solution, and does not easily precipitate in a coating film of the solution.

This compound has good solubility in a solvent, is stable in solution, hardly precipitates in a coating film of the solution, and exhibits high light resistance when used as a recording layer of an optical recording medium. . However, dithiol, which is a raw material intermediate, has a strong sulfur odor, is unstable to air, and is oxidized to give disulfide. Therefore, it is necessary to strictly control the atmosphere during synthesis, and the production is not always easy. It was. In addition, since a strong odor is emitted along with thermal decomposition, there is a concern that a strange odor may be emitted along with recording when an optical recording medium is used.
JP 2001-80217 A JP 2001-143317 A JP-A-6-40161 JP 2001-260536 A JP-A-4-78576 JP 11-334205 A JP-A-11-334204 JP 2001-271001 A JP 2000-43423 A JP 2001-96918 A JP 2000-228028 A JP 2001-71639 A JP 2002-2110 A JP 2001-234154 A JP 2003-320754 A

  The present invention has been made in view of the above circumstances, and its purpose is excellent in solubility in a solvent, no odor accompanying thermal decomposition, easy synthesis, and formation of a recording layer of an optical recording medium. It is an object of the present invention to provide a dye for forming an aminocatechol-based metal complex compound-based recording layer that is compatible with optical recording with blue laser light and exhibits high light resistance, heat resistance, and moist heat resistance.

  Another object of the present invention is to provide an optical recording medium having a recording layer using the recording layer forming dye and a recording method thereof.

As a result of intensive studies to solve the above problems, the inventors of the present invention have a specific structure as a heteroatom-containing ligand of a metal complex compound, which has excellent solubility in a solvent and generates odor accompanying thermal decomposition. It is easy to synthesize, and an optical recording medium using this for the recording layer can be recorded well with blue laser light, and at the same time, has been found to exhibit high light resistance, high heat resistance, and high heat and humidity resistance. The invention has been completed.
That is, the gist of the present invention is as follows.

[1] A dye for forming a recording layer of an optical recording medium, comprising a compound represented by the following general formula [I].

（式中、環Ａ及び環Ａ’は、それぞれ独立して、置換基を有していても良い芳香族炭化水素環又は置換基を有していても良い芳香族複素環を示し、Ｑ及びＱ’は、それぞれ独立して、置換基を有していても良い芳香族炭化水素環基又は置換基を有していても良い芳香族複素環基を示す。ここで、ＱとＱ’は、互いに直接的に又は連結基を介して結ばれていても良い。Ｍは金属原子を示す。）

(In the formula, ring A and ring A ′ each independently represent an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocyclic ring which may have a substituent, and Q and Q ′ each independently represents an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent, where Q and Q ′ are And may be connected to each other directly or via a linking group. M represents a metal atom.)

[2] In [1], M in the general formula [I] represents Ni, Pd, Pt, Cu, Co, Fe, Au, Cr, or Mn. Dye for use.

[3] In [1] or [2], the recording layer containing the recording layer forming dye is irradiated with light having an irradiance of 0.55 W / m ² at a temperature of 58 ° C. and a humidity of 50% for 40 hours. A dye for forming a recording layer of an optical recording medium, wherein when the light resistance test is performed, the absorption intensity at a wavelength of 350 nm of the recording layer after the light resistance test is 80% or more with respect to the absorption intensity before the test.

[4] An optical recording medium comprising a recording layer containing the recording layer forming dye described in [1] to [3].

[5] The recording method for an optical recording medium according to [4], wherein recording is performed with a laser beam having a wavelength of 350 to 530 nm.

  The recording layer forming dye of the optical recording medium of the present invention is excellent in solubility in a solvent, does not generate odor due to thermal decomposition, and is easily synthesized. Moreover, it is excellent in light resistance, heat resistance, and wet heat resistance. By using this recording layer forming dye in the recording layer, it is possible to provide an inexpensive and high density optical recording medium excellent in film properties that can be recorded favorably with blue laser light.

  Embodiments of the present invention will be specifically described below, but the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

[Dye for recording layer formation]
The recording layer forming dye of the optical recording medium according to the present invention contains a compound represented by the following general formula [I].

（式中、環Ａ及び環Ａ’は、それぞれ独立して、置換基を有していても良い芳香族炭化水素環又は置換基を有していても良い芳香族複素環を示し、Ｑ及びＱ’は、それぞれ独立して、置換基を有していても良い芳香族炭化水素環基又は置換基を有していても良い芳香族複素環基を示す。ここで、ＱとＱ’は、互いに直接的に又は連結基を介して結ばれていても良い。Ｍは金属原子を示す。）

(In the formula, ring A and ring A ′ each independently represent an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocyclic ring which may have a substituent, and Q and Q ′ each independently represents an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent, where Q and Q ′ are And may be connected to each other directly or via a linking group. M represents a metal atom.)

  The compound represented by the general formula [I] has a cis / trans isomer, and is actually represented by the cis isomer represented by the above [I] and the following general formula [II]. There is a trans form. However, these cis-trans isomers can be interchanged instantaneously and can be said to be substantially synonymous. However, as described later, when the substituents Q and Q ′ are linked to each other, when the connecting chain between them is short, there is a case where the transition to the trans isomer can hardly occur with only the cis isomer. .

{Explanation of words}
In the present invention, the “aromatic ring” means a ring having aromaticity, that is, a ring having a (4p + 2) π electron system (p is a natural number), and therefore, “aromatic hydrocarbon ring” and “aromatic heterocycle”. "Hydrocarbon ring group" means both "aromatic hydrocarbon ring group (aryl group)" and "non-aromatic hydrocarbon ring group", and "heterocyclic group" It means both “aromatic heterocyclic group (heteroaryl group)” and “non-aromatic heterocyclic group”.
In the present invention, “may have a substituent” means that it may have one or more substituents.

{Explanation about Rings A and A '}
In the general formula [I], ring A and ring A ′ are each independently an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocyclic ring which may have a substituent. is there.
In general formula [I], ring A and ring A ′ may be the same or different from each other, but are preferably the same from the viewpoint of ease of synthesis.

<About the skeletons of rings A and A '>
The skeleton constituting the aromatic hydrocarbon ring and aromatic heterocycle of rings A and A ′ is preferably a 5- or 6-membered monocyclic ring or a condensed ring thereof, more preferably a 6-membered monocyclic ring or a condensed thereof. It is a ring, and particularly preferably a 6-membered monocycle in terms of light resistance. Specific examples of the 6-membered single ring or condensed ring thereof include aromatic hydrocarbon rings having about 6 to 18 carbon atoms such as benzene ring and naphthalene ring, or 4 to 16 carbon atoms such as pyridine ring and pyrazine ring. A degree of aromatic heterocycle. As the aromatic heterocycle, a nitrogen-containing aromatic heterocycle is preferable to a sulfur-containing aromatic heterocycle in terms of light resistance.

  Specific examples of the structure of the skeleton constituting the aromatic hydrocarbon ring and aromatic heterocycle of rings A and A ′ include the following. In the following, the part a is bonded to N and the part b is bonded to O through a single bond. Alternatively, the part a may be bonded to O and the part b may be bonded to N via a single bond. The same applies to a and b in the following exemplary structures.

  The structure of the skeleton constituting the aromatic hydrocarbon ring and the aromatic heterocycle of the rings A and A ′ is as follows from the viewpoint of solubility, more preferably from the viewpoint of light resistance. A benzene ring or a pyridine ring that does not emit light is preferable, and a benzene ring is particularly preferable.

<Substituent which Ring A and Ring A ′ may have>
The substituent that ring A and ring A ′ may have is not particularly limited as long as it does not adversely affect the performance of the dye, but is a bulky substituent in order to avoid intermolecular aggregation. A tertiary alkyl group is particularly preferred as the substituent. As a substitution position, at least one substituent is bonded to the atom adjacent to the carbon atom to which the oxygen atom is bonded in the general formula [I] (provided that it is bonded to —NQ, —NQ ′). In particular, when ring A and ring A ′ are 6-membered rings, they are substituted at both the ortho and para positions relative to the carbon atom to which the oxygen atom is bonded. Most preferably it has a group.

  As the substituent that the ring A and the ring A ′ may have, preferred substituents include, for example, a halogen atom, a hydroxyl group, a nitro group, a cyano group, an alkyl group, an alkenyl group, an alkynyl group, an aryl group, and a heteroaryl. Group, alkoxy group, aryloxy group, heteroaryloxy group, alkylthio group, arylthio group, heteroarylthio group, amino group, acyl group, aminoacyl group, ureido group, sulfonamido group, carbamoyl group, sulfamoyl group, sulfamoyl group It is selected from the group consisting of amino group, alkoxycarbonyl group, aryloxycarbonyl group, heteroaryloxycarbonyl group, alkylsulfonyl group, arylsulfonyl group, heteroarylsulfonyl group, imide group, silyl group and the like. These substituents may be further substituted with an arbitrary substituent. Specific examples of the substituent in this case include the specific examples of the optional substituents listed above.

Specific examples of the substituent that the ring A and the ring A ′ may have include the following.
An alkyl group having about 1 to 6 carbon atoms such as a methyl group, an ethyl group, an isopropyl group, an n-butyl group, a t-butyl group, a 2-pentyl group, and an n-hexyl group;
An alkenyl group having about 2 to 6 carbon atoms such as an ethynyl group and a propynyl group,
An alkynyl group having about 2 to 6 carbon atoms, such as an acetylenyl group,
An aryl group having about 6 to 20 carbon atoms such as a phenyl group, a naphthyl group, an anthranyl group, a phenanthryl group, a ferrocene ring group,
A heteroaryl group having about 3 to 20 carbon atoms, such as thienyl group, furyl group, pyridyl group, imidazolyl group, pyrazolyl group,
An alkoxy group having about 1 to 6 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, a t-butoxy group, and an n-butoxy group;
Aryloxy groups having about 6 to 20 carbon atoms such as phenoxy group and naphthoxy group,
A heteroaryloxy group having about 3 to 20 carbon atoms such as a thienyloxy group and a pyridyloxy group;
An alkylthio group having about 1 to 6 carbon atoms such as methylthio group, ethylthio group, isopropylthio group, n-butylthio group, sec-butylthio group, and 3-pentylthio group;
An arylthio group having about 6 to 20 carbon atoms such as a phenylthio group and a naphthylthio group;
A heteroarylthio group having about 3 to 20 carbon atoms, such as thienylthio group, pyridylthio group, imidazolylthio group, pyrazolylthio group,
An amino group optionally having a substituent having about 1 to 20 carbon atoms such as a dimethylamino group, a diethylamino group, and a diphenylamino group;
An acyl group having about 2 to 20 carbon atoms such as an acetyl group and a pivaloyl group;
An acylamino group having about 2 to 20 carbon atoms such as an acetylamino group and a propionylamino group;
A ureido group having about 2 to 20 carbon atoms, such as a 3-methylureido group,
A sulfonamide group having about 1 to 20 carbon atoms such as a methanesulfonamide group and a benzenesulfonamide group;
A carbamoyl group having about 1 to 20 carbon atoms such as a dimethylcarbamoyl group and an ethylcarbamoyl group;
A sulfamoyl group having about 1 to 20 carbon atoms, such as an ethylsulfamoyl group,
A sulfamoylamide group having about 1 to 20 carbon atoms such as a dimethylsulfamoylamide group,
An alkoxycarbonyl group having about 2 to 6 carbon atoms such as a methoxycarbonyl group and an ethoxycarbonyl group;
An aryloxycarbonyl group having about 7 to 20 carbon atoms such as a phenoxycarbonyl group and a naphthoxycarbonyl group;
A heteroaryloxycarbonyl group having about 5 to 20 carbon atoms, such as a pyridylcarbonyl group,
An alkylsulfonyl group having about 1 to 6 carbon atoms such as a methanesulfonyl group, an ethanesulfonyl group, and a trifluoromethanesulfonyl group;
An arylsulfonyl group having about 6 to 20 carbon atoms such as a benzenesulfonyl group and a monofluorobenzenesulfonyl group;
A heteroarylsulfonyl group having about 3 to 20 carbon atoms, such as a thienylsulfonyl group,
An imide group having about 4 to 20 carbon atoms, such as a phthalimide group,
Silyl group trisubstituted with a substituent selected from alkyl and aryl groups

These substituents may be further substituted with the substituents mentioned here.
In addition, when there are two or more substituents on the rings A and A ′, or when these substituents further have two or more substituents, they may be the same or different. Groups may be bonded to form a ring.

{Preferred structure of rings A and A '}
Ring A and ring A ′ are particularly preferably those having the structures shown below.

Examples of R include the examples of the substituents described above independently, and n represents an integer of 1 to 4. Here, when n is 2 or more, adjacent Rs are combined to form an alkylene group having about 2 to 6 carbon atoms such as — (CH ₂ ) ₃ — or — (CH ₂ ) ₄ —; or —OCH _{2 O -, - O (CH} 2) ring a is possible to form a 2 _O- etc. alkylenedioxy group having about 1 to 4 carbon atoms, such as, may form a ring fused to a '.

  Among these, as said R, it is a C3-C20 alkyl group which may have a substituent, a C3-C20 alkoxy group which may have a substituent, More preferably, carbon A C3-C15 alkyl group which may have a substituent, particularly preferably a C3-C10 alkyl group, and especially a C3-C10 branched alkyl group or cyclic alkyl Groups are preferred because they avoid aggregation between molecules.

  n is preferably an integer of 1 to 3, and more preferably 1 or 2.

  The substitution position of R is preferably in the ortho position or para position, or in the ortho position and para position with respect to the oxygen atom to which rings A and A ′ are bonded in general formula [I]. Preferably, substituents are substituted at least in the ortho and para positions from the viewpoint of improving solubility.

  Moreover, it is preferable to have at least one electron-donating substituent from the viewpoint of increasing absorption near 405 nm.

{Explanation on Substituents Q and Q '}
In the general formula [I], Q and Q ′ are each independently an aromatic hydrocarbon ring group (aryl group) which may have a substituent or an aromatic heterocyclic ring which may have a substituent. Group (heteroaryl group).
In the general formula [I], the substituent Q and the substituent Q ′ may be the same or different from each other, but are preferably the same from the viewpoint of ease of synthesis.

<About the ring skeleton of the substituents Q and Q '>
The skeleton of the ring constituting the aryl group and heteroaryl group of the substituents Q and Q ′ is usually a 5-membered or 6-membered monocycle or a condensed ring thereof, preferably a 6-membered monocycle or a condensed ring thereof. In view of light resistance, it is more preferably a 6-membered monocycle. Specific examples of the 5-membered or 6-membered monocyclic ring or a condensed ring group thereof include an aryl group having about 6 to 18 carbon atoms such as an anthranyl group, a pyrenyl group, a ferrocene ring group, a phenyl group, and a naphthyl group; or Examples thereof include heteroaryl groups having about 4 to 16 carbon atoms such as thienyl group, furyl group, imidazolyl group, thiazolyl group, quinoxalyl group, phenanthryl group, pyridyl group, pyrazinyl group and the like. The heteroaryl group is preferably a nitrogen-containing heteroaryl group over a sulfur-containing heteroaryl group in terms of light resistance.

The rings constituting the substituents Q and Q ′ are each directly or an alkylene group having about 1 to 6 carbon atoms such as — (CH ₂ ) ₃ — and — (CH ₂ ) ₄ —; or —OCH _{2 O -, - O (CH 2} ) 2 O- or the like may be connected through a linking group such as alkylenedioxy groups having about 1 to 4 carbon atoms.

  Of the aryl group and heteroaryl group, a phenyl group, a pyridyl group, a pyrimidyl group, or a pyrazinyl group is particularly preferable, and among them, a phenyl group is particularly preferable.

<Substituents that the substituents Q and Q ′ may have>
The substituents that the substituents Q and Q ′ may have are any monovalent substituents as long as they do not affect the stability of the dye, and specifically, rings A and A ′. And the same substituents as those mentioned above. Furthermore, a carbonyl group (acyl group (—COR ¹ ), carbamoyl group (—CONR ¹ R ² )) (R ¹ and R ² are hydrocarbon groups which may have a substituent. The same shall apply hereinafter), an acyloxy group. (—OC (O) R ¹ ), sulfonyl group (—SO ₂ R ¹ ), sulfamoyl group (—SO ₂ NR ³ R ⁴ ) (R ³ , R ⁴ and R ⁵ described later have a substituent. ^May be a hydrocarbon group or a hydrogen atom. The same shall apply hereinafter.), An amide group (—NR ³ COR ⁴ ), a ureido group (—NR ³ C (O) NR ⁴ R ⁵ ), a sulfonamide group (—NR ³ SO ₂ OR ⁴ ), an imide group and the like. Among these, specific hydrocarbon group-substituted moieties include alkyl groups that may have the substituents mentioned above for rings A and A ′, aryl groups that may have substituents, and substituents. The thing similar to the example of the heteroaryl group which may have is mentioned.

More preferable examples of the substituents Q and Q ′ include the following 1) or 2).
1) A bulky substituent selected from the group consisting of an alkyl group which may have a substituent, an alkoxy group which may have a substituent, and an alkylthio group which may have a substituent. 2) Substitution of Hammett An electron-withdrawing group having a base constant σm of 0.00 <σm <0.90, more preferably 0.30 <σm <0.90 and a functional group having a high polarizability

More specifically, examples of the substituent that the substituents Q and Q ′ may have include a cyano group, a fluorine atom, an aminocarbonyl group, a nitro group, a haloalkyl group, a haloalkoxy group, an acyl group, and an alkoxycarbonyl group. , Aryloxycarbonyl group, alkylsulfonyl group, haloalkylsulfonyl group, acyloxy group (—OC (O) R ¹ ), sulfonyl group (—SO ₂ R ¹ ), etc. Is an alkyl group which may have a substituent described above for the substituents of rings A and A ′, an aryl group which may have a substituent, or a heteroaryl group which may have a substituent The same as the above example.

  The position of the substituent may be any position as seen from the carbon atom in which Q and Q ′ are bonded to the nitrogen atom in the general formula [I], but from the viewpoint of increasing absorption near a wavelength of 400 nm, In view of the carbon atom bonded to the nitrogen atom, it is preferable that the adjacent carbon (ortho position) has no substituent. Moreover, in order to raise the solubility of a compound, the case where it has a substituent in ortho position is preferable.

That is, with respect to the substituent introduced into the ring of the substituents Q and Q ′,
(1) When a substituent is present at the ortho position, distortion occurs between the ring of the substituents Q and Q ′ and the rings A and A ′, and the solubility of the compound represented by the general formula [I] is improved. .
(2) When there is a coordinative substituent to the central metal M at the ortho position, the compound represented by the general formula [I] takes the Oh type, and the compound has improved solubility.
(3) When there is a substituent other than the ortho position, the spread of conjugation between the substituents Q and Q ′ and the rings A and A ′ increases, and the absorption near the wavelength of 405 nm tends to increase.
(4) As a substituent of the substituents Q and Q ′, when a bulky alkyl group or a Hammett's substituent constant σm is positive and has an electron-withdrawing group, the compound represented by the general formula [I] is dissolved. Improves.
Therefore, it is preferable to select a substituent and a substitution position thereof in order to obtain the required solubility and absorption characteristics based on the above (1) to (4).

{Explanation about the central metal M}
M is not particularly limited as long as it is a metal atom that can take a tetracoordinate form, but preferably includes a group 10 metal atom of Ni, Pd, or Pt; Co, Fe, Cu, or Au, Cr, Mn, More preferred are Ni and Pd from the absorption spectrum shape.

{Molecular weight of the compound represented by the general formula [I]}
The compound represented by the general formula [I] usually has a molecular weight of 2000 or less, particularly 1500 or less, particularly preferably 1000 or less, from the viewpoint of preventing a decrease in sensitivity due to a decrease in absorbance.
The compound represented by the general formula [I] is usually preferably insoluble in water.

{Specific examples of compounds represented by general formula [I]}
Preferable specific examples of the compound represented by the general formula [I] include, for example, those exemplified below. However, it is not limited to the following compounds.

  In the following exemplary compounds, Ni is shown as the central metal, but these may be replaced with any of Pd, Pt, Cu, Co, Fe, Au, Cr, Mn, and others. In the following, Me: methyl group, Et: ethyl group, Pr: propyl group, Bu: butyl group, Ac: acetyl group.

{Synthesis Method of Compound Represented by General Formula [I]}
The compound having the structure represented by the general formula [I] is, for example, Russ. J. et al. Gen. Chem. , 66, 1842 (1996) and the like. That is, a commercially available substituted catechol is heated in the presence of a tertiary amine in a substituted aniline and a hydrocarbon solvent to obtain an intermediate ligand, and this aminocatechol and a metal salt are heated at room temperature or in the presence of a tertiary ammonium salt. An aminocatechol metal complex can be obtained by metallization while bubbling air in acetonitrile under reflux. When synthesizing a compound in which ring A and ring A ′ are different, two kinds of aminocatechol metal complexes are mixed and heated to reflux in a solvent to cause a ligand exchange reaction, so that ring A and ring A ′ are different. Aminocatechol metal complexes can be synthesized.

{Solubility of compounds represented by general formula [I]}
The compound represented by the general formula [I] has excellent solubility in a solvent for preparing a coating solution for forming a recording layer, which will be described later, does not generate odor due to thermal decomposition, and is easy to synthesize. . It should be noted that the solubility in this case means that the solubility in a coating solvent evaluated at room temperature (usually 15 to 30 ° C.) (a state where there is no visual precipitation) is 1.5% by weight or more, and more preferably 2 0.0% by weight or more, particularly preferably 3.0% by weight or more. In the application of the present invention, the upper limit of the solubility is not particularly limited, but is usually 20% by weight or less, particularly about 10% by weight or less.

[Recording layer]
When the recording layer is formed using the recording layer forming dye of the optical recording medium of the present invention, one of the compounds represented by the general formula [I] may be used alone, or two or more of them may be mixed. May be used.

  In order to form a recording layer of an optical recording medium using the recording layer forming dye of the present invention, a vacuum deposition method, a sputtering method, a doctor blade method, a cast method, a spin coating method, an immersion method, etc. are generally performed. A thin film forming method can be used. Of these, spin coating is preferred from the standpoints of mass productivity and cost. When the recording layer is formed by spin coating, the rotational speed is preferably 500 to 5000 rpm, and after spin coating, treatment such as heating or exposure to solvent vapor may be performed as necessary. The film thickness of the recording layer is not particularly limited, but is usually 10 nm to 5 μm, preferably 20 nm to 2 μm.

  The recording layer may contain a binder in order to improve the film properties. As the binder, one kind of known materials such as polyvinyl alcohol, polyvinyl pyrrolidone, ketone resin, nitrocellulose, cellulose acetate, polyvinyl butyral, and polycarbonate can be used alone or in admixture of two or more. When the ratio of the binder occupying the recording layer is too high, the recording sensitivity is remarkably lowered. Therefore, when the binder and further various additives described below are used, the ratio of the recording layer forming dye of the present invention to the formed recording layer is The amount is usually 10% by weight or more, preferably 50% by weight or more, particularly preferably 90% by weight or more.

  Further, the recording layer may contain a singlet oxygen quencher for improving stability and light resistance, a recording sensitivity improving agent, and the like.

  Examples of the singlet oxygen quencher include chelates of acetylacetonate, bisphenyldithiol, salicylaldehyde oxime, bisdithio-α-diketone, and the like, and transition metals, and these may be used alone. Two or more kinds may be used in combination.

  Examples of the recording sensitivity improver include metal compounds in which a metal such as a transition metal is contained in the form of atoms, ions, clusters, etc., for example, ethylenediamine complex, azomethine complex, phenylhydroxyamine complex, phenanthroline. And organometallic compounds such as complex, dihydroxyazobenzene complex, dioxime complex, nitrosoaminophenol complex, pyridyltriazine complex, acetylacetonate complex, metallocene complex, and so on. You may use, and may use 2 or more types together. The type of metal atom is not particularly limited, but a transition metal is preferable.

  In the recording layer, dyes of other systems can be used in combination as required. Other types of dyes that can be used in combination have absorption in the laser light wavelength range for recording, absorb the energy of the irradiated laser light, and decompose and evaporate into the recording layer, reflective layer or substrate of the irradiated part. It is preferable to form pits accompanied by thermal deformation such as melting. In addition, a dye suitable for recording with a near-infrared laser beam having a wavelength selected from the range of 770 to 830 nm for CD-R and a red laser beam selected from the range of 620 to 690 nm for DVD-R is used in combination. Thus, an optical recording material corresponding to recording with laser beams in a plurality of wavelength regions can be used. Specific examples of other dyes include metal-containing azo dyes, phthalocyanine dyes, naphthalocyanine dyes, cyanine dyes, azo dyes, squarylium dyes, metal-containing indoaniline dyes, and triarylmethane dyes. Examples include dyes, merocyanine dyes, azurenium dyes, naphthoquinone dyes, anthraquinone dyes, indophenol dyes, xanthene dyes, oxazine dyes, and pyrylium dyes, and these may be used alone. Two or more kinds may be used in combination.

  When the recording layer is formed by a doctor blade method, a cast method, a spin coating method, a dipping method, etc., first, the recording layer forming dye, binder, singlet oxygen quencher, recording sensitivity improver and other agents of the present invention are used. A pigment is dissolved in a solvent to prepare a coating solution. The solvent is not particularly limited as long as it does not attack the substrate, and ketone alcohol solvents such as diacetone alcohol and 3-hydroxy-3-methyl-2-butanone, cellosolv solvents such as methyl cellosolve and ethyl cellosolve Chain hydrocarbon solvents such as n-hexane and n-octane, alicyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, n-butylcyclohexane, t-butylcyclohexane and cyclooctane, Ether solvents such as diisopropyl ether and dibutyl ether, perfluoroalkyl alcohol solvents such as tetrafluoropropanol (TFP), octafluoropentanol and hexafluorobutanol, and solvents such as methyl lactate, ethyl lactate and methyl isobutyrate. Roxyester solvents and the like can be mentioned, but perfluoroalkyl alcohol solvents such as TFP, octafluoropentanol, hexafluorobutanol and the like are more preferable from the industrial aspect, and are generally used industrially at present. It is particularly preferable to use TFP. In addition, these solvents may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  The concentration of the recording layer forming dye of the present invention in the coating solution is appropriately determined according to the solvent solubility, but is usually 0.7% by weight or more, preferably 1.0% by weight or more, and usually 10% by weight. % Or less, preferably 3.0% by weight or less. If the dye concentration in the coating solution is excessively low, the formation efficiency of the recording layer is deteriorated. If the dye concentration in the coating solution is excessively high, problems such as dye crystallization occur in the film forming process.

  In addition, in order to efficiently recover the excess dye after spin coating, the dye compound can be dissolved in the coating solvent even when the concentration is usually 1.5 times or more, preferably 2 times or more the concentration of the coating solution. It is preferable that

  The singlet oxygen quencher is usually used in an amount of about 5 to 30% by weight with respect to the dye, and the recording sensitivity improver is usually used in an amount of about 10 to 30% by weight with respect to the dye.

[Optical recording medium]
The optical recording medium of the present invention has a recording layer formed as described above using the recording layer forming dye of the present invention.

  As the substrate of the optical recording medium on which the recording layer is formed, a substrate transparent to the laser beam to be used, such as glass and various plastics, is preferably used. Examples of plastics include acrylic resin, methacrylic resin, polycarbonate resin, vinyl chloride resin, vinyl acetate resin, nitrocellulose, polyester resin, polyethylene resin, polypropylene resin, polyimide resin, polystyrene resin, epoxy resin, etc., In view of cost, moisture absorption resistance and the like, polycarbonate resin injection molded is preferable.

  Usually, a layer other than the recording layer such as a reflective layer, a protective layer, and an undercoat layer is further provided on the substrate as necessary, and used as an optical recording medium.

  Examples of the reflective layer include those made of a metal such as gold, silver, aluminum, or an alloy thereof, but silver is preferable to gold or aluminum because of the reflectance with respect to laser light having a wavelength of 550 nm or less. The metal reflective layer is formed on the recording layer by vapor deposition, sputtering, ion plating, or the like. Here, an intermediate layer may be provided between the metal reflective layer and the recording layer in order to improve the adhesion between the layers, or to increase the reflectance.

  Examples of the material for the protective layer formed on the reflective layer include an ultraviolet curable resin composition.

  Furthermore, two optical recording media having the above-described configuration may be bonded via an adhesive layer to form a double-sided recording type optical recording medium, or the recording layer may be provided on both sides of the substrate or on one side.

  Information recording on the optical recording medium obtained as described above is usually performed by irradiating the recording layer with laser light focused to about 0.4 to 0.6 μm. When the recording layer absorbs the energy of the laser beam, thermal deformation such as decomposition, heat generation, and melting occurs in the laser beam irradiated portion. The recorded information is reproduced by reading the difference in reflectance between the portion where the thermal deformation is caused by the laser beam and the portion where the thermal deformation does not occur.

  For high-density recording, the shorter the wavelength of the laser beam used, the better, and laser light with a wavelength of 350 nm to 530 nm is particularly preferable. Typical examples of such laser light include blue laser light having center wavelengths of 405 nm and 410 nm, and blue-green high-power semiconductor laser light having a center wavelength of 515 nm. Other than these, (a) a semiconductor laser beam capable of continuous oscillation having a fundamental oscillation wavelength of 740 to 960 nm, or (b) a solid-state laser beam capable of continuous oscillation having a fundamental oscillation wavelength of 740 to 960 nm that is excited by the semiconductor laser beam. The light etc. which are obtained by wavelength-converting either by a 2nd harmonic generation element (SHG) are also mentioned.

  The SHG may be any piezo element that lacks reflection symmetry, but KDP, ADP, BNN, KN, LBO, a compound semiconductor, and the like are preferable. As a specific example of the second harmonic, in the case of a semiconductor laser having a fundamental oscillation wavelength of 860 nm, a wavelength 430 nm of its harmonic wave, and in the case of a solid-state laser excited by a semiconductor laser, a Cr-doped LiSrAlF6 crystal (basic oscillation wavelength of 860 nm ) Wavelength of 430 nm and the like.

  Of the absorption wavelength and absorbance of the optical recording medium, the preferred one depends on the type of laser light used for recording. For example, for a blue laser having a central wavelength of 405 to 410 nm, the maximum absorption wavelength (λmax) of the absorption spectrum of the optical recording medium is 280 to 400 nm, and the molar extinction coefficient at λmax is 5000 or more, more preferably The maximum absorption wavelength (λmax) of the absorption spectrum of the optical recording medium is 370 to 490 nm for a blue laser having a center wavelength of 430 nm, and is preferably 30,000 or more, more preferably 30,000 or more. The molar extinction coefficient is preferably 20000 or more.

  In particular, the aminocatechol metal complex compound according to the present invention represented by the general formula [I] is suitable for an optical recording medium using these blue laser beams. Moreover, since the aminocatechol metal complex compound according to the present invention is relatively easy to synthesize, an inexpensive optical recording medium can be provided.

In addition, since the aminocatechol metal complex compound according to the present invention is excellent in light resistance, an optical recording medium containing the aminocatechol metal complex compound according to the present invention in a recording layer is usually a high temperature and high humidity and direct light. It is hard to deteriorate even if left under. The aminocatechol metal complex generally has an absorption in the vicinity of 300 to 400 nm, and it is required that the deterioration of the absorption is small. The light resistance shows a change in intensity at a wavelength of 350 nm. Specifically, an optical recording medium containing the aminocatechol metal complex compound according to the present invention in the recording layer is preferably a temperature of 58 ° C.-humidity. Even if left for 40 hours under irradiation with 50% -xenon lamp (intensity 0.55 W / m ² ), 80% or more, preferably 90% or more, more preferably 95% or more of the aminocatechol metal complex compound is deteriorated. Remain without. Further, among the optical recording media containing the aminocatechol metal complex compound in the recording layer, particularly preferable ones are usually left for 40 hours or longer, preferably 80 hours or longer, more preferably 120 hours or longer under the irradiation conditions. 99% or more remains without deterioration.

  Further, the aminocatechol metal complex compound according to the present invention is excellent in recording laser sensitivity. Specifically, among the optical recording media containing the aminocatechol metal complex compound according to the present invention in the recording layer, the laser intensity when irradiated with blue laser light having a center wavelength of 404 nm and NA = 0.85 is preferable. Good recording pits can be formed even at 10 mW or less. It should be noted that good recording pit formation is possible here when the recording surface of an optical recording medium is irradiated with blue laser light having a specific laser intensity, and the formation of pits can be confirmed visually or using an optical microscope. Say.

  Furthermore, the aminocatechol metal complex compound according to the present invention is excellent in film properties. That is, it is industrially advantageous in that no whitening phenomenon derived from crystallization of the compound is observed on the disk surface after the recording layer is formed by spin coating.

  Hereinafter, embodiments of the present invention will be described more specifically by way of examples. However, the present invention is not limited to these examples as long as the gist thereof is not exceeded.

<Synthesis of optical recording media>
Example 1

  3,5-Di-tert-butylcatechol (3 g, 13.5 mmol) was dissolved in n-heptane (25 mL), and triethylamine (1.1 mL) and 2-ethylaniline (1.978 g, 16.3 mmol) were dissolved in this solution. And heated to reflux for 12 hours. After cooling to room temperature, the mixture was concentrated, and the resulting product was purified by silica gel column chromatography to obtain the target aminocatechol compound as a brown liquid in a yield of 87% (EI MS: 325).

  The aminocatechol compound (3.12 g, 9.61 mmol) obtained above was dissolved in acetonitrile (125 mL), and triethylamine (3.2 mL) and nickel nitrate hexahydrate (1.26 g, 4.32 mmol) were dissolved in this solution. ) And refluxed for 6 hours under air bubbling. Cooled to room temperature and filtered the product. The obtained solid was washed with hot water, further washed with hot methanol, and then collected by filtration to obtain the objective nickel aminophenolate complex [A] as a dark green solid in 79% yield (EI). MS: 704).

Example 2
In Example 1, the target product was obtained from 3,5-di-tert-butylcatechol and 2-ethylaniline in the same manner except that 3-amino-N, N-diethyl-benzamide was used instead of 2-ethylaniline. Was obtained as a brown liquid in a yield of 59% (EI MS: 397).

  From the aminocatechol compound obtained above and nickel nitrate hexahydrate, the following nickel aminophenolate complex [B], which is the target product, was obtained as a dark green solid in a yield of 79% in the same manner as in Example 1. (EI MS: 848).

<Preparation of optical recording medium>
Each nickel aminophenolate complex prepared in Examples 1 and 2 was dissolved in 1.0% by weight in methylene chloride, and after removing fine dust by filtration, the resulting solution had a diameter of 120 mm and a thickness of 1. The solution was dropped on a 2 mm injection-molded polycarbonate substrate, applied by spin coating (4900 rpm), and dried at 80 ° C. for 30 minutes to obtain a transparent coating film (film thickness of about 50 nm).
No whitening phenomenon due to crystallization of the compound was observed in any of the coating films.

<Light resistance test>
The optical recording medium produced by the above method was subjected to a light resistance test under the conditions of temperature 58 ° C.−humidity 50% / xenon lamp (intensity 0.55 W / m ² ) irradiation. Table 1 shows the rate of change in absorption intensity at a wavelength of 350 nm.
From this result, it is clear that the optical recording medium using the aminocatechol metal complex compound according to the present invention is remarkably excellent in light resistance.

<Evaluation of optical recording media>
When an optical recording medium produced by the above method was irradiated with semiconductor laser light having a central wavelength of 404 nm, NA = 0.85, and recording laser intensity of 7.5 mW, formation of good recording pits was confirmed in any case. .

Claims (5)

A dye for forming a recording layer of an optical recording medium, comprising a compound represented by the following general formula [I].

(In the formula, ring A and ring A ′ each independently represent an aromatic hydrocarbon ring which may have a substituent or an aromatic heterocyclic ring which may have a substituent, and Q and Q ′ each independently represents an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent, where Q and Q ′ are And may be connected to each other directly or via a linking group. M represents a metal atom.)   The dye for forming a recording layer of an optical recording medium according to claim 1, wherein M in the general formula [I] represents Ni, Pd, Pt, Cu, Co, Fe, Au, Cr, or Mn. 3. The light resistance test according to claim 1, wherein the recording layer containing the recording layer forming dye is irradiated with light having an irradiance of 0.55 W / m ² at a temperature of 58 ° C. and a humidity of 50% for 40 hours. In this case, the recording layer forming dye of the optical recording medium has an absorption intensity at a wavelength of 350 nm of the recording layer after the light resistance test of 80% or more with respect to the absorption intensity before the test.   An optical recording medium comprising a recording layer containing the recording layer forming dye according to any one of claims 1 to 3.   5. The recording method for an optical recording medium according to claim 4, wherein recording is performed with a laser beam having a wavelength of 350 to 530 nm.