JPH09226248A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a recording material for an optical recording medium which can be applied to a high packing density disk system and has excellent heat resistance and preservation stability by providing a recording layer containing a dye represented by a specific formula directly or via an undercoating layer on a board and providing a reflecting layer and a protective layer thereon as desired. SOLUTION: A recording layer containing dye represented by general formula I (where M is bivalent to tetravalent metal atoms, R<5> to R<11> are each hydrogen atom, a monovalent aliphatic hydrocarbon group, (o) is an integer f 0 to 2, X<1> to X<4> are each hydrogen atom, or an alkyl group, R<1> to R<4> are each hydrogen atom or an lakyl group, (k), (l), (m), (n) are each an integer of 0 to 4 which do not simultaneously become '0') is provided directly or via an undercoating layer on a board, and a reflecting layer, a protective layer is provided thereon as desired to form the optical recording medium. Specifically, the recording layer 2 is provided via the undercoating layer 3 as required on the board 1, and further a protective layer 4 is provided as required to form a writing once optical disk.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording medium, and more particularly, to irradiating a light beam to cause an optical change such as transmittance and reflectance of a recording material.
The present invention relates to an optical recording medium on which information can be recorded, reproduced, and additionally recorded.

[0002]

2. Description of the Related Art The current write-once optical disk system (WO
RM, CD-R), the oscillation wavelength of the laser used is 770.
nm to 790 nm, and the recording medium records at the above wavelength,
It is configured to be able to reproduce. In the future, it is indispensable to increase the capacity of the recording medium as the amount of information increases. Therefore, it is easily expected that the wavelength of the laser used for recording and reproduction will inevitably be shortened. As a write-once optical disc for data, a number of proposals have been made using a cyanine dye or a phthalocyanine dye as a recording material (for example, JP-A-57-82093 discloses a disc using a cyanine dye as a recording material. JP-A-58-56892, JP-A-58-112790,
JP-A-58-114989, JP-A-59-85791
JP-A-60-83236, JP-A-60-8984
No. 2, JP-A-61-25886, and those using a phthalocyanine dye as a recording material are described in JP-A-61-150243 and JP-A-61-177287.
JP-A-61-154888, JP-A-61-246
No. 091, JP-A-62-39286, JP-A-63-3
No. 7791, JP-A-63-39888, etc.), but a recording material which is excellent in light resistance and storage stability and which can be recorded and reproduced by an optical pickup using a laser of 700 nm or less is still being developed. It has not been done yet.

The current CD-R disk system is also configured so that recording and reproduction can be performed at a laser oscillation wavelength of 770 nm to 790 nm. This system is also required to have a large capacity and a short recording / reproducing wavelength, similarly to the above. In this regard, current CDs and CD-ROMs
Al is coated on the unevenness of the substrate itself.
Has a small wavelength dependence of the reflectance, so that it is possible to reproduce even if the laser wavelength is shortened in the future. However,
The CD-R uses a dye having a maximum absorption wavelength at 680 nm to 750 nm for the recording layer, and is set so as to obtain a high reflectance at 770 nm to 790 nm from the optical constant and the film thickness configuration. In this case, the reflectivity is extremely low, so that it is impossible to cope with the shortening of the laser wavelength, and information recorded and reproduced by the current CD-R system cannot be reproduced by a future system. Until now CD
Numerous proposals have been made for -R using a cyanine dye / metal reflection layer, a phthalocyanine dye / metal reflection layer, or an azo metal chelate dye / metal reflection layer as a recording material (for example, a cyanine dye / metal reflection layer is used. JP-A-1-159842, JP-A-2-42652, JP-A-2-13656 and JP-A-2-168446 each use a phthalocyanine dye as a recording material. Japanese Patent Laid-Open No. 1-1765
No. 85, JP-A-3-215466, JP-A-4-113
886, JP-A-4-226390, JP-A-5-12
72, JP-A-5-171052, and JP-A-5-116.
456, JP-A-5-69860, JP-A-5-139
Nos. 044-46186, and those using an azo metal chelate dye as a recording material are described in JP-A-4-46186.
JP-A-4-141489, JP-A-4-36088
And Japanese Unexamined Patent Application Publication No. 5-279580), however, no solution has been found to solve such a problem.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above situation, and has a high density optical disk using a semiconductor laser having an oscillation wavelength shorter than that of the conventional system. It provides a recording material for optical recording media with excellent light resistance and storage stability that can be applied to systems, and a CD-ROM that can be recorded and played back with the current system and can be played back even in the next-generation high-density optical disk system. It is an object to provide a recording material for an R medium.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that by providing a recording layer containing a dye having a specific structure as a main component, a high-density semiconductor laser having an oscillation wavelength of 700 nm or less can be used. It is found that it can be applied to optical disc systems, and furthermore, it is possible to obtain a high reflectance even in the wavelength region of 700 nm or less by using this dye in combination with an organic dye currently used as a recording material for CD-R. Have been found possible, and the present invention has been completed.

[0006] That is, according to the present invention, firstly, a recording layer is provided on a substrate directly or via an undercoat layer, and if necessary, a reflection layer and a protective layer are provided on the recording layer. In a recording medium, there is provided an optical recording medium characterized in that the recording layer contains at least one compound represented by the following general formula (I).

Embedded image [In the formula, M, X ^{1 to} X ⁴ , R ^{1 to} R ⁴ , k, l, m and n
Represents the following, respectively. M: a divalent, trivalent or tetravalent metal atom which may have two hydrogen atoms, or an oxygen atom or a halogen atom,
Alternatively, a (-OR ⁵ ) o group, a (-OSiR ⁶ R ⁷ R ⁸ ) o group, a (-
OPOR ⁹ R ¹⁰ ) o group or a metal atom having a (—OCOR ¹¹ ) o group, R ^{5 to} R ¹¹ : each independently a hydrogen atom, a substituted or unsubstituted monovalent aliphatic hydrocarbon group, or a substituted or unsubstituted Of 1
Valent aromatic hydrocarbon group, o: an integer of 0 to 2, X ^{1 to} X ⁴ : each independently a hydrogen atom, a substituted or unsubstituted alkyl group, R ^{1 to} R ⁴ : each independently a hydrogen atom, substituted or An unsubstituted linear or branched alkyl group, k, l, m, n: each independently an integer of 0 to 4, provided that k,
l, m and n cannot be 0 at the same time. Note that k,
When l, m and n are 3 or less, the other substituent on the benzene ring is a hydrogen atom or a halogen atom. Secondly, in the optical recording medium described in the first, in the compound represented by the general formula (I), each of k, l, m and n is independently an integer of 0 to 2, and Provided is an optical recording medium in which the substitution position of the substituent is 1 or 4. Third, in the optical recording medium described in the first or second,
There is provided an optical recording medium, wherein the recording layer contains at least one compound represented by the general formula (I) and an organic dye having a maximum absorption wavelength in the range of 680 nm to 750 nm. Fourthly, in the optical recording medium described in the above third, the optical recording medium in which the organic dye having the maximum absorption wavelength at 680 nm to 750 nm is at least one of pentamethine cyanine dye, phthalocyanine dye and azo metal chelate dye. Provided. Fifth,
The optical recording medium according to any one of the first to fourth aspects, wherein the reflective layer is made of aluminum or gold. Sixthly, there is provided an optical recording medium according to any one of the first to fifth aspects, wherein the protective layer is made of an ultraviolet curable resin.

The optical recording medium of the present invention has the general formula (I)
Provided that a recording layer containing at least one compound represented by the formula (1) is provided, so that recording and reproduction can be performed with a laser beam in a wavelength range of 700 nm or less, and further, light resistance and storage stability are excellent. In the embodiment, the above general formula (I)
At least one compound represented by the formula: 680 to 750;
Since a recording layer made of a mixture with an organic dye having a maximum absorption wavelength in nm is provided, the CD-R
It can be used as a medium, and even if it is a next-generation high-density optical disk system, the described information can be reproduced.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
The optical recording medium of the present invention is characterized in that the recording layer contains at least one compound represented by the above general formula (I). First, the general formula (I) used in the present invention
In the general formula (I), M represents two hydrogen atoms, or a divalent, trivalent or tetravalent metal atom which may have an oxygen atom or a halogen atom, or ( -OR ⁵ ) o group, (-OSiR ⁶
R ⁷ R ⁸ ) o group, (-OPOR ⁹ R ¹⁰ ) o group or (-O
COR ¹¹ ) represents a metal atom having an o group. Where R ⁵
To R ¹¹ are each independently a hydrogen atom, substituted or unsubstituted 1
Represents a valent aliphatic hydrocarbon group or a substituted or unsubstituted monovalent aromatic hydrocarbon group, and o represents an integer of 0 to 2. X ^{1 to} X ⁴ each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group, and R ^{1 to} R ⁴ each independently represent a hydrogen atom or a substituted or unsubstituted linear or branched alkyl group. In addition, k, l, m and n are each independently 0 to 4
Represents the integer, and k, l, m, and n are never 0 at the same time. When k, l, m and n are 3 or less,
The other substituent on the benzene ring is a hydrogen atom or a halogen atom.

In particular, in the general formula (I), [CX ¹ (COOR
¹ ) ₂ ] The so-called α-substituted compound in which the number of substitution of the substituent represented by k or the like is 1 or 2 and the substitution position is 1 or 4 is advantageous when adjusting the absorption wavelength and when thinned. ,
The high refractive index of the thin film can be realized by the association inhibition, and the high reflectance can be achieved when the recording medium is used.

In the general formula (I), k = l = m =
When n = 1, the following four isomers (A) to (D) are present, and the absorption band of the recording film can be slightly widened, which contributes to widening the recording wavelength margin and the recording power margin. Often do.

Embedded image

Embedded image

Embedded image

Embedded image In the above formula, Y ^{1 to} Y ⁴ are [CX ¹ (COOR ¹ ) ₂ ] k to [CX ⁴
(COOR ⁴ ) ₂ ] n.

Specific examples of the alkyl group represented by X ^{1 to} X ^{4 in} the general formula (I) include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, isobutyl group, n-pentyl group, Neopentyl group, isoamyl group, n-hexyl group,
Primary alkyl groups such as n-octyl group, n-nonyl group, n-decyl group and n-dodecyl group; isopropyl group, sec
-A secondary alkyl group such as a butyl group. Further, these alkyl groups may be substituted at a specific position with a halogen atom or the like.

In the general formula (I), specific examples of the alkyl groups represented by R ^{1 to} R ⁴ include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, isobutyl group, n-pentyl group, Neopentyl group, isoamyl group, n-hexyl group,
Primary alkyl groups such as n-octyl group, n-nonyl group, n-decyl group and n-dodecyl group; isopropyl group, sec
-Secondary alkyl group such as butyl group; tert-butyl group,
tert-hexyl group, tert-amyl group, tert
-A tertiary alkyl group such as an octyl group. Also,
These alkyl groups may be substituted at a specific position with a halogen atom or the like.

In the general formula (I), specific examples of M include hydrogen atom; Ca, Mg, Zu, Cu, Ni, Pd, Fe,
Divalent metal such as Pb, Co, Pt, Cd, Ru; A
l, In, Fe, Ga, Tl, Mn and other trivalent metal halides, hydroxyl compounds, alkoxy compounds, trialkylsiloxy compounds, etc .; and Si, Ti, Sn, C
Examples thereof include halides, hydroxyl compounds, alkoxy compounds, trialkylsiloxy compounds and oxides of tetravalent metals such as r, Ga, Sn, Mn, Zr and V. Also,
In the definition of R ^{5 to} R ¹¹ , the monovalent aliphatic hydrocarbon group is a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, or a te group.
rt-butyl group, amyl group, hexyl group, octyl group,
Examples thereof include alkyl groups such as decyl group, dodecyl group and octadecyl group, and alkenyl groups such as vinyl group, allyl group, isopropenyl group, 1-butenyl group, 2-butenyl group and 2-pentenyl group. Examples of the monovalent aromatic hydrocarbon group include a phenyl group and a benzyl group. Examples of the substituent include a halogen atom such as fluorine, chlorine, and bromine, a carbon trifluoride group, a cyano group, and an ester group.

Specific examples of the compound represented by the general formula (I) include those shown in Tables 1- (1) and 1- (2).

[0015]

[Table 1- (1)]

[0016]

[Table 1- (2)]

In the recording layer, as described above, the main component is a mixture of at least one compound represented by the general formula (I) and an organic dye having a maximum absorption wavelength at 680 to 750 nm. As a result, the CD-R recording medium can be recorded and reproduced by the current system and can be reproduced only by the next-generation system. In this case, as the dye having the maximum absorption wavelength at 680 to 750 nm, pentamethine cyanine dye, phthalocyanine dye and azo metal chelate dye are preferable.

Preferred examples of pentamethine cyanine dyes include those represented by the following general formula (II).

[Chemical 6] In the formula, R ²¹ and R ²² are an alkyl group having 1 to 3 carbon atoms, R ²³ ,
R ²⁴ represents a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms;
Represents an acid anion. Note that the aromatic ring may be condensed with another aromatic ring, or may be substituted with an alkyl group, a halogen atom, an alkoxy group, or an acyl group.

Preferred examples of the phthalocyanine dye include the following general formula (III-1) or (III-2)
Are shown.

Embedded image In the formula, M ¹ is Ni, Pd, Cu, Zn, Co, Mn, F
e, TiO or VO, X ^{5 to} X ⁸ each independently represent -OR or -SR at the substitution position α-position, and R represents an optionally substituted linear, branched or alicyclic group having 3 to 12 carbon atoms. Represents an alkyl group or an aryl group which may be substituted. Substituents on the benzene ring other than X ^{5 to} X ⁸ are a hydrogen atom or a halogen atom.

[0020]

Embedded image In the formula, M ² is Si, Ge, In, or Sn, and is X ⁹ to X.
¹² is each independently -OR or -SR at the substitution position α.
R is an optionally substituted straight chain having 3 to 12 carbon atoms,
A branched or alicyclic alkyl group or an aryl group which may be substituted, wherein Y ⁵ and Y ⁶ are each —OSiR ²⁵ R ²⁶ R
²⁷ , -OCOR ²⁵ R ²⁶ R ²⁷ , or -OPOR ²⁵ R ²⁶ R ²⁷
Wherein R ^{25 to} R ²⁷ each independently represent 1 to 10 carbon atoms.
Represents an alkyl group or an aryl group. Substituents on the benzene ring other than X ^{9 to} X ¹² are a hydrogen atom or a halogen atom.

Preferred examples of the azo metal chelate dye include one or more azo metal chelate compounds of an azo compound represented by the following general formula (IV) and a metal, and the metal is preferable. For example, Ni, P
Examples thereof include t, Pd, Co, Cu and Zn.

Embedded image In the formula, A represents a residue which forms a heterocyclic ring together with the carbon atom and the nitrogen atom to which it is bonded, and B represents an aromatic ring together with the two carbon atoms to which it is bonded. Or a residue forming a heterocyclic ring, and X represents a group having active hydrogen.

When the at least one dye represented by the general formula (I) of the present invention and the at least one dye represented by the general formulas (II) to (IV) are used in combination, the weight composition ratio is Inventive dye / [(II) to (IV) dye] =
10/100 to 90/100, preferably 40/100
~ 20/100. When both dyes are used in combination, the recording layer has a film thickness of 500Å to 5 μm, preferably 1000.
It is from Å to 5000Å.

Next, the structure of the recording medium of the present invention will be described. FIG. 1 is a diagram showing an example of a layer configuration applicable to the recording medium of the present invention, which is an example of a write-once optical disc. The recording layer 2 is provided on the substrate 1 via an undercoat layer 3 if necessary.
And, if necessary, a protective layer 4. Further, a hard coat layer can be provided under the substrate 1 as needed. FIG. 2 is a diagram showing another example of a layer structure applicable to the recording medium of the present invention, which is an example of a CD-R medium. A reflective layer 6 is formed on the recording layer 2 having the structure shown in FIG.
Is provided. The recording medium of the present invention may have an air sandwich structure in which the recording layer (organic thin film layer) having the structure shown in FIGS. A bonding structure in which the layers are bonded via a protective layer may be used.

Next, the required characteristics of the constituent layers and the constituent materials thereof will be described. 1) Substrate As a necessary characteristic of the substrate, when recording / reproducing is performed from the substrate side, it must be transparent to the laser beam to be used. However, when recording / reproducing is performed from the recording layer side, it is not necessary to be transparent. As the substrate material, for example, polyester, acrylic resin, polyamide, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, plastic such as polyimide, glass, ceramic, metal or the like can be used. Note that a guide groove or guide pit for tracking, and a preformat such as an address signal may be formed on the surface of the substrate.

2) Recording Layer The recording layer is capable of recording some information by causing some kind of optical change by irradiation of laser light, and
In this recording layer, at least one compound represented by the general formula (I), and optionally the general formula (II) to
It is necessary that at least one of the dyes represented by (IV) is contained. In addition, these dyes are used for improving the optical characteristics, recording sensitivity, and signal characteristics of other organic dyes and metals,
Of course, it is possible to use it by mixing or laminating it with a metal compound. Other organic dyes in this case include polymethine dyes, naphthalocyanine dyes, phthalocyanine dyes,
Squarylium series, croconium series, pyrylium series, naphthoquinone series, anthraquinone (indanthrene) series,
Examples include xanthene-based, triphenylmethane-based, azulene-based, tetrahydrocholine-based, phenanthrene-based, triphenothiazine-based dyes, and metal complex compounds.
Examples of metals and metal compounds include In, Te, Bi,
Se, Sb, Ge, Sn, Al, Be, TeO ₂ , Sn
O, As, Cd and the like can be mentioned, and each of them can be used in the form of dispersion mixing or lamination. Further, various materials such as a polymer material, for example, an ionomer resin, a polyamide resin, a vinyl resin, a natural polymer, silicone, a liquid rubber, or a silane coupling agent may be dispersed and mixed in the dye, For improvement purposes, they can be used together with stabilizers (e.g. transition metal complexes), dispersants, flame retardants, lubricants, antistatic agents, surfactants, plasticizers and the like.

The recording layer is formed by vapor deposition, sputtering, C
It can be carried out by usual means such as VD or solvent application. When using the coating method, the above dye or the like is dissolved in an organic solvent, and spray, roller coating,
It can be performed by a conventional coating method such as dipping or spin coating. As the organic solvent used, generally, alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, amides such as N, N-dimethylacetamide and N, N-dimethylformamide, sulfoxides such as dimethyl sulfoxide. Ethers such as tetrahydrofuran, dioxane, diethyl ether and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogenated carbons such as chloroform, methylene chloride, dichloroethane, carbon tetrachloride and trichloroethane,
Aromatics such as benzene, xylene, monochlorobenzene and dichlorobenzene, or methoxyethanol;
Cellsolves such as ethoxyethanol, and hydrocarbons such as hexane, pentane, cyclohexane, and methylcyclohexane. The thickness of the recording layer is 100
Å-10 μm, preferably 200Å-2000Å is suitable.

3) Undercoat layer The undercoat layer is an adhesive layer, a barrier against water or gas, storage stability of the recording layer, reflectance, protection of the substrate from a solvent, guide grooves, and guides. It is used to form pits and preformats. For the purpose of the polymer material, for example, ionomer resin, polyamide, vinyl resin, natural resin, natural polymer, silicone, various polymer compounds such as liquid rubber and silane coupling agent and the like can be used,
In addition to the above-mentioned polymer materials, inorganic compounds such as SiO ₂ , MgF ₂ , SiO, TiO ₂ , Z
nO, TiN, SiN, etc., and further, a metal or semimetal such as Zn, Cu, Ni, Cr, Ge, Se, A
u, Ag, Al and the like can be used. For the purpose, a metal such as Al, Au, Ag or the like, or an organic thin film having a metallic luster such as a methine dye or a xanthene-based dye can be used. Cured resin, thermosetting resin, thermoplastic resin, or the like can be used. The thickness of the undercoat layer is 0.
The thickness is suitably from 01 to 30 μm, preferably from 0.05 to 10 μm.

4) Reflective Layer The reflective layer may be made of a metal or semi-metal which has a high reflectance and is resistant to corrosion. Examples of materials include Au,
Ag, Al, Cr, Ni, Fe, Sn and the like.
Au and Al are most preferred in terms of reflectivity and productivity. These metals and metalloids may be used alone or as two or more alloys. Examples of the film forming method include vapor deposition and sputtering, and the film thickness is 50 to 5000.
Å, preferably 100 to 3000 Å.

5) Protective Layer, Substrate-side Hard Coat Layer The protective layer or substrate-side hard coat layer protects the recording layer (reflective / absorptive layer) from scratches, dust, dirt, etc. It is used for the purpose of improving stability and reflectance. For these purposes, the materials shown in the undercoat layer can be used. Also,
As an inorganic material, SiO, SiO _{2 and the} like can also be used, and as an organic material, polymethyl acrylate, polycarbonate, epoxy resin, polystyrene, polyester resin, vinyl resin, cellulose, aliphatic hydrocarbon resin,
Thermosoftening and heat melting resins such as natural rubber, styrene-butadiene resin, chloroprene rubber, wax, alkyd resin, drying oil, and rosin can also be used. The most preferable of the above materials is an ultraviolet curable resin having excellent productivity. The thickness of the protective layer or the hard coat layer on the substrate surface is 0.01 to 30 μm, preferably 0.05 to 10 μm.
Is appropriate.

In the present invention, the undercoat layer, the protective layer and the hard coat layer on the substrate surface are the same as in the case of the recording layer.
A stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, a plasticizer and the like can be contained.

[0031]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

Example 1 Example 1 A photopolymer was formed on a polymethylmethacrylate substrate having a thickness of 1.2 μm, and the depth was 1200 Å and the half width was 0.4 μ
m on a substrate on which a guide groove having a track pitch of 1.4 μm was formed. 1, a 1,2-dichloroethane solution was applied by spinner, and a recording layer having a thickness of 800 ° was provided to obtain a recording medium.

Examples 2 to 8 In Example 1, specific examples of compounds No. Instead of 1.
Compound specific example No. 2, No. 4, no. 6, no.
7, No. 9, No. 14, No. Recording media of Examples 2 to 8 were obtained in the same manner as in Example 1 except that No. 21 was used.

Comparative Example 1 In Example 1, compound specific example No. A recording medium of Comparative Example 1 was obtained in the same manner as in Example 1, except that the compound represented by the following formula (V) was used instead of 1.

Embedded image

Using the recording media of Examples 1 to 8 and Comparative Example 1 described above, light was incident on the substrate under the following recording conditions for recording, and then C / N and reflectance were measured at the recording position by reproducing light. did. Table 2 shows the results. Recording condition: Laser oscillation wavelength 680 nm Recording frequency 1.25 MHz Recording linear velocity 1.2 m / sec Reproduction condition: Laser oscillation wavelength 680 nm Reproduction power 0.25-0.3 mW continuous light Scanning band width 30 KHz Light fastness test condition: Light fastness test 4 10,000 Lux, Xe light, 50 hours continuous irradiation Storage test 85 ° C, 85%, 720 hours

[0036]

[Table 2]

Example 9 On a 1.2 mm thick injection-molded polycarbonate substrate having guide grooves with a depth of 1000 Å, a half width of 0.45 μm and a track pitch of 1.6 μm, the compound No. 1 was dissolved in a mixed solution of methylcyclohexane, 2-methoxyethanol, methyl ethyl ketone, and tetrahydrofuran, and spin-coated to form a recording layer having a thickness of 1800Å, and then Au2000Å by sputtering.
The reflective layer was provided, and a protective layer of 5 μm was further provided on the reflective layer with an acrylic photopolymer to obtain a recording medium.

Examples 10 to 16 In Example 9, compound specific examples No. Compound Specific Example No. 1 in place of 6, no. 7, No. 9, N
o. 11, No. 18, No. 19, no. Examples 10 to 16 in the same manner as in Example 9 except that 22 was used.
The recording medium of

Comparative Example 2 In Example 9, the specific compound No. A recording medium of Comparative Example 2 was obtained in the same manner as in Example 9, except that the compound represented by the formula (V) used in Comparative Example 1 was used instead of 1.

EFM signals were recorded on the recording media of Examples 9 to 16 and Comparative Example 2 with a lasing wavelength of 680 nm and a beam diameter of 1.4 μm while tracking (linear velocity 1.4 m / sec). The reproduced waveform was observed by reproducing with the continuous light of the same laser. Table 3 shows the results.

[0041]

[Table 3]

Example 17 A compound represented by the following formula (VI) was formed on a 1.2 mm thick injection-molded polycarbonate substrate having a guide groove with a depth of 1000 Å, a half width of 0.45 μm and a track pitch of 1.6 μm. Specific compound No. 21 and the weight ratio (1 /
It is dissolved in a mixed solvent of 1) methylcyclohexane, 2-methoxyethanol, methyl ethyl ketone, and tetrahydrofuran, and is applied with a spinner to form a recording layer having a thickness of 1700Å, and then Au2000Å by sputtering.
Was formed, and a 5 μm protective layer of an acrylic photopolymer was further provided thereon to obtain a recording medium.

[0043]

Embedded image

Examples 18 and 19 In Example 17, specific compound No. 21 instead of Compound Specific Example No. 21, respectively. 18, No. Except for using Example 19, recording media of Examples 18 and 19 were obtained in the same manner as Example 17.

Examples 20 and 21 In Example 17, compound specific examples No. 21 instead of Compound Specific Example No. 21, respectively. 2, No. 21 is used,
Further, recording media of Examples 20 and 21 were obtained in the same manner as in Example 17, except that the compound represented by the following formula (VII) was used in place of the compound represented by the above formula (VI).

[0046]

Embedded image

Examples 22 and 23 In Example 17, specific compound No. 21 instead of Compound Specific Example No. 21, respectively. 1, No. Using 25,
Further, recording media of Examples 22 and 23 were obtained in the same manner as in Example 17, except that the compound represented by the following formula (VIII) was used in place of the compound represented by the above formula (VI).

[0048]

Embedded image

Comparative Examples 3 to 5 In Example 17, the recording layers were each formed by the above general formula (V
Comparative Examples 3 to 5 were conducted in the same manner as in Example 17, except that only the compound represented by the formula (VII), the compound represented by the general formula (VII), and the compound represented by the general formula (VIII) were used. A recording medium was obtained.

EFM signals were recorded on the recording media of Examples 17 to 23 and Comparative Examples 3 to 5 with a semiconductor laser beam having an oscillation wavelength of 780 nm and a beam diameter of 1.6 μm while tracking (linear velocity 1.4 m / sec). ), Reproduction was performed with continuous light of the laser and a semiconductor laser having an oscillation wavelength of 680 nm and a beam diameter of 1.4 μm, and the reproduction waveform was observed. Table 4 shows the results.
Shown in

[0051]

[Table 4]

[0052]

According to the first aspect of the present invention, since the recording layer contains at least one of the compounds represented by the general formula (I) in the recording layer, the optical recording medium has a high light absorption at a wavelength of 700 nm or less. Recording with laser light in a wavelength range of 700 nm or less, which enables high-density recording,
Reproducible, and excellent in light resistance and storage stability.

The optical recording medium according to claim 2 has the general formula (I):
In the compound represented by the formula (1), each of k, l, m, and n is 0, 1 or 2, and the substitution position of the substituent is 1 or 4, the improvement of the refractive index of the recording layer is achieved. Thus, it becomes possible to obtain a high reflectance optical recording medium.

An optical recording medium according to a third aspect of the present invention comprises at least one of the compounds represented by the general formula (I) and 680 to 7
Since the recording layer contains an organic dye having a maximum absorption wavelength of 50 nm, recording and reproduction can be performed with the current system, and even in the next-generation high-density optical disc system, the recorded information can be recorded. It becomes possible to reproduce.

An optical recording medium according to claim 4 is 680 to 750.
Since at least one of a cyanine dye of pentamethine, a phthalocyanine dye, and an azo metal chelate dye is selected as the organic dye having a maximum absorption wavelength in nm, high-quality signal characteristics can be recorded.

In the optical recording medium of the fifth aspect, since the reflecting layer is made of aluminum or gold, it is possible to realize a high reflectance and a CD-R medium with good productivity.

In the optical information recording medium according to the sixth aspect, since the protective layer is made of the ultraviolet curable resin, it is possible to form a protective layer having high productivity.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a layer configuration as a general write-once optical recording medium applicable to a recording medium of the present invention.

FIG. 2 is a diagram showing a layer configuration example for a CD-R applicable to the recording medium of the present invention.

[Explanation of symbols]

 1 substrate 2 recording layer (organic dye layer) 3 undercoat layer 4 protective layer 5 hard coat layer 6 reflective layer

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yasunobu Ueno 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (6)

[Claims] 1. An optical recording medium in which a recording layer is provided on a substrate directly or via an undercoating layer, and if necessary, a reflective layer and a protective layer are provided thereon, the recording layer having the following: An optical recording medium comprising at least one compound represented by formula (I). Embedded image [In the formula, M, X ^{1 to} X ⁴ , R ^{1 to} R ⁴ , k, l, m and n
Represents the following, respectively. M: a divalent, trivalent or tetravalent metal atom which may have two hydrogen atoms, or an oxygen atom or a halogen atom,
Alternatively, a (-OR ⁵ ) o group, a (-OSiR ⁶ R ⁷ R ⁸ ) o group, a (-
OPOR ⁹ R ¹⁰ ) o group or a metal atom having a (—OCOR ¹¹ ) o group, R ^{5 to} R ¹¹ : each independently a hydrogen atom, a substituted or unsubstituted monovalent aliphatic hydrocarbon group, or a substituted or unsubstituted Of 1
Valent aromatic hydrocarbon group, o: an integer of 0 to 2, X ^{1 to} X ⁴ : each independently a hydrogen atom, a substituted or unsubstituted alkyl group, R ^{1 to} R ⁴ : each independently a hydrogen atom, substituted or An unsubstituted linear or branched alkyl group, k, l, m, n: each independently an integer of 0 to 4, provided that k,
l, m and n cannot be 0 at the same time. Note that k,
When l, m and n are 3 or less, the other substituent on the benzene ring is a hydrogen atom or a halogen atom. ] 2. The compound represented by the general formula (I) is
k, l, m and n are each independently an integer of 0 to 2,
The optical recording medium according to claim 1, wherein the substitution position of the substituent is 1 or 4. 3. The recording layer containing at least one compound represented by the general formula (I) and an organic dye having a maximum absorption wavelength at 680 nm to 750 nm. 2. The optical recording medium according to 2. 4. The cyanine dye of pentamethine, wherein the organic dye having the maximum absorption wavelength in the range of 680 nm to 750 nm is pentamethine.
The optical recording medium according to claim 3, wherein the optical recording medium is at least one of a phthalocyanine dye and an azo metal chelate dye. 5. The optical recording medium according to claim 1, wherein said reflection layer is made of aluminum or gold. 6. The optical recording medium according to claim 1, wherein the protective layer is made of an ultraviolet curable resin.