JP4737599B2 - Metal-containing squarylium compound and optical recording medium using the compound - Google Patents

Description

  The present invention relates to a metal-containing squarylium compound and an optical recording medium using the compound, and more particularly, to record and / or reproduce information using recording light having a wavelength of 350 nm to 530 nm, particularly blue laser light having a wavelength of 405 nm. The present invention relates to a write-once type optical recording medium suitable for the above.

  Conventionally, magneto-optical recording media, phase change recording media, chalcogen oxides, and the like have been proposed as recording media for optically recording / reproducing information. Among them, information recording is performed only once by a laser. As a write-once type optical recording medium capable of recording, a CD-R is mass-produced and widely used because of its low cost and easy manufacturing process. The recording capacity is about 0.65 GB, and the demand for higher-density and large-capacity optical recording media is increasing with a dramatic increase in the amount of information.

  Conventionally, the wavelength of near-infrared laser (usually 780 nm) is used for recording / reproducing of the CD-R. Recently, high-density, large-capacity recording using a short-wavelength (680 nm) red semiconductor laser has been performed. An realized organic dye-based optical recording medium (DVD-R) has also been developed and put into practical use. Furthermore, there is a demand for an optical recording medium capable of high-density recording and reproduction using a blue semiconductor laser having a shorter wavelength (350 to 530 nm).

  By the way, a general write-once optical recording medium is formed by sequentially laminating a recording layer made of an organic dye, a light reflecting layer made of a metal such as gold or silver, and a protective layer made of resin on a transparent disk-shaped substrate. Composed. Information is written (recorded) by irradiating the recording layer with laser light, the recording layer absorbs the light, and the temperature rises locally, causing a physical or chemical change (for example, generation of pits). Information is recorded using the change in optical characteristics. On the other hand, reading (reproduction) of information is also performed by irradiating a laser having the same wavelength as the recording laser, and the portion where the optical characteristics of the recording layer have changed (recorded portion) and the portion that has not changed (unrecorded portion) Information is reproduced by detecting the difference in reflectance from the. In order to form and detect good pits, the dye used in the recording layer is required to exhibit high absorbance at the wavelength of the laser light used.

  Patent Document 1 discloses a recording / reproducing method for recording and reproducing information by irradiating a laser beam having a wavelength of 530 nm or less from the recording layer side in an optical recording medium having a recording layer containing an organic dye. . Specific organic dyes used in the optical recording medium include cyanine dyes (Patent Document 2), dyes having a pyridone azo skeleton (Patent Document 3), dyes having a dicyanovinylphenyl skeleton (Patent Document 4), and coumarin. A compound (Patent Document 5), an azo metal chelate dye (Patent Document 6), and the like have been proposed.

  In general, as a dye suitable for the recording layer of an optical recording medium, the optical properties and decomposition behavior with respect to the wavelength of the blue laser light to be used are good, and at the same time, the dye is dissolved in a solvent and the solution is applied to a substrate and dried Thus, the solubility in a solvent when forming a recording layer is required, and the above dyes have advantages and disadvantages, and there is a demand for dyes that sufficiently satisfy these characteristics.

Patent Documents 7 and 8 propose a squarylium dye, but the absorption wavelength is in the range of 530 to 600 nm and is not appropriate because it is not in the wavelength region of blue laser light.

JP-A-4-074690 Japanese Patent Laid-Open No. 11-053758 JP-A-11-334204 Japanese Patent Laid-Open No. 11-334206 JP 2000-043423 A JP 2001-158862 A JP 2004-264805 A JP 2004-258514 A

  It is an object of the present invention to have high light absorption characteristics in a wavelength range of 350 to 530 nm that can be recorded and reproduced with a blue semiconductor laser, and to have excellent thermal decomposition behavior and solubility in a solvent, and excellent light resistance and durability. The object is to provide a metal squarylium compound and an optical recording medium using the compound.

  As a result of intensive studies, the present inventors have found that a specific metal-containing squarylium compound has high light absorption in the region of 350 to 530 nm, and has excellent thermal decomposition behavior and solubility in a solvent, light resistance and durability. It has been found that it is excellent in properties and useful as a recording layer of an optical recording medium, and the present invention has been completed.

  That is, the present invention is a metal-containing squarylium compound comprising a squarylium compound represented by the following general formula (A) and a metal salt or metal ion.

In general formula (A), R ₁ represents a hydroxyl group, an amino group, or a sulfonamide group, and R ₂ represents an optionally substituted linear or branched alkyl group, halogenated alkyl group, cyanoalkyl group, alkoxy group, R ₃ , R ₄ , R ₅ and R ₆ each independently represent a hydrogen atom, a halogen atom, or a substituted or unsubstituted amino group, hydroxy group, cyano group, nitro A group, an amino group, a sulfo group, or an optionally substituted linear or branched alkyl group, alkenyl group, alkoxy group, aryl group, heterocycle, acyl group, or alkoxycarbonyl group (provided that R ₃ and R ₄ , R ₄ and R ₅ , R ₅ and R ₆ may be linked to form a ring), X is O, S, Se, N—R ₇ , C—R ₈ R ₉ (R ₇ , R ₈ , R ₉ each independently represents an optionally substituted linear or branched alkyl group, halogenated alkyl group, phenylalkyl group, aryl group, acyl group, sulfonyl group, alkoxycarbonyl group, or alkylsulfonic acid group. )

  In the metal-containing squarylium compound represented by the general formula (A), the metal may be Ni, Co, Zn, Cu, Pt, Ti, Al, V, Mn, Fe, Mo, W, Sn, A metal-containing squarylium compound, which is at least one metal selected from the group consisting of Ru, Cr, and Pb.

  Further, according to the present invention, in an optical recording medium having a recording layer on which information can be written and / or read by laser light on a substrate, the recording layer contains at least one of the metal-containing squarylium compounds. An optical recording medium characterized by the above.

  The present invention also provides an optical recording medium comprising at least one metal-containing squarylium compound that records and / or reproduces information with a laser beam selected from a wavelength region having a wavelength of 350 nm to 530 nm.

  In the metal-containing squarylium compound of the present invention, the metal interacts with one or more squarylium molecules as a metal salt even if the metal is present as a complex by binding to one or more squarylium molecules as a metal ion. A weak bond may be formed. The coordination number in the case of a complex varies depending on the type of metal and the substituent of the squarylium compound.

  The present invention is a metal-containing squarylium compound comprising the squarylium compound represented by the general formula (A) and a metal salt or metal ion, and these specific metal-containing squarylium compounds are excellent in the region of 350 to 530 nm. Have excellent light absorption, excellent thermal decomposition behavior and solubility in solvents, excellent light resistance and durability, useful as a recording layer for optical recording media, and optimal as an optical recording medium for forming recording layers It is.

  Hereinafter, the metal-containing squarylium compound of the present invention will be described in detail.

  The metal-containing squarylium compound of the present invention is a compound comprising a squarylium compound represented by the general formula (A) and a metal salt or metal ion.

In the general formula (A), R ₁ represents a hydroxyl group, an amino group, or a sulfonamide group.

The sulfonamide group is represented by —NHSO ₂ X, wherein X represents a substituted or unsubstituted linear or branched alkyl group, a substituted or unsubstituted unsaturated hydrocarbon, a substituted or unsubstituted aromatic ring, In particular, a linear or branched alkyl group having 1 to 6 carbon atoms substituted with a fluorine atom is preferable.

Specifically, a C1-C6 perfluoroalkyl group such as a trifluoromethyl group, a pentafluoroethyl group, a heptafluoropropyl group, 2, 2, 2-trifluoroethyl group, 3, 3, 3-trifluoropropyl, etc. And an alkyl group substituted with a perfluoroalkyl group having 2 to 6 carbon atoms in total such as a group, 2, 2, 3, 3, 3-pentafluoropropyl group, and the like. _{-CF 2 CF 3, -CH 2 CF} 3, -CF 3 is particularly preferred.

In the general formula (A), R ₂ represents an optionally substituted linear or branched alkyl group, halogenated alkyl group, cyanoalkyl group, alkoxy group, phenylalkyl group, or alkylsulfonic acid group.

  Examples of the linear or branched alkyl group which may be substituted include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group, sec-butyl group, n-pentyl group, Examples thereof include linear or branched alkyl groups having 1 to 20 carbon atoms such as n-hexyl group, n-heptyl group, n-octyl group, n-decyl group, n-dodecyl group, n-octadecyl group, etc. A linear or branched alkyl group having 1 to 10 carbon atoms.

  The halogenated alkyl group is represented by the following general formula (B).

_{-C n X m H 2n + 1} -m (B)
(In the formula, X represents a halogen atom, n represents a natural number of 1 to 12, and m represents a natural number of 1 to 25.)

  The halogenated alkyl group is a linear or branched halogenated alkyl group having 1 to 12 carbon atoms. If the number of carbon atoms exceeds 12, the mass extinction coefficient of the squarylium compound may decrease. The halogen atom of the halogenated alkyl group is not particularly limited, but a fluorine atom, that is, a fluorinated alkyl group is particularly preferable from the viewpoint of excellent effects of improving the heat resistance and light resistance of the squarylium compound.

  Examples of the fluorinated alkyl group include trifluoromethyl group, 2,2,2-trifluoroethyl group, 3,3,3-trifluoropropyl group, 4,4,4-trifluorobutyl group, 5,5,5, 5-trifluoropentyl group, 6,6,6-trifluorohexyl group, 8,8,8-trifluorooctyl group, 2-methyl-3,3,3-trifluoropropyl group, perfluoroethyl group, perfluoropropyl Group, perfluorobutyl group, perfluorohexyl group, perfluorooctyl group, 2-trifluoromethyl-perfluoropropyl group and the like.

  The cyanoalkyl group is not particularly limited, but is preferably a linear or branched cyanoalkyl group having 1 to 10 carbon atoms, and the number of substituted cyano groups is preferably 1 to 3. Particularly preferred are propionitrile group, butyronitrile group, pentylnitrile group, 1-methylpropionitrile group, 1-methylbutyronitrile group and the like.

  Examples of the alkoxy group include methoxy, ethoxy, propoxy, isopropoxy, butoxy, 2-methoxyethoxy, pentyloxy, hexyloxy, octyloxy, decyloxy group, methoxymethyl group, methoxyethyl group, methoxypropyl group, and methoxybutyl. Group, methoxyhexyl group, methoxyoctyl group, ethoxyethyl group, ethoxyethyl group, ethoxypropyl group, ethoxybutyl group, ethoxyhexyl group, ethoxyoctyl group, propoxymethyl group, propoxypropyl group, propoxyhexyl group, butoxyethyl group, etc. 1 to 18 linear or branched alkoxy groups, preferably 3 to 9 carbon atoms.

  As said phenylalkyl group, the C1-C8 thing of an alkyl group is preferable, Moreover, a phenyl group may have a substituent, an alkyl group, a hydroxyl group, a sulfonic acid group, an alkylsulfonic acid group, nitro. It may have at least one substituent from the group consisting of a group, an amino group, an alkoxy group, a halogenated alkyl group and a halogen. Examples of the phenylalkyl group include benzyl group, phenethyl group, phenylpropyl group, phenyl-α-methylpropyl group, phenyl-β-methylpropyl group, phenylbutyl group, and phenylpentyl group.

  The alkylsulfonic acid group is not particularly limited, but an alkylsulfonic acid group having 1 to 6 carbon atoms is preferable. Specific examples include a methyl sulfonic acid group, an ethyl sulfonic acid group, and a propyl sulfonic acid group.

In the general formula (A), R ₃ , R ₄ , R ₅ and R ₆ are each independently a hydrogen atom, a halogen atom, or a substituted or unsubstituted amino group, hydroxy group, cyano group, nitro group, sulfo group. Or an optionally substituted linear or branched alkyl group, alkenyl group, alkoxy group, aryl group, heterocycle, acyl group, or alkoxycarbonyl group (provided that R ₃ and R ₄ , R ₄ and R ₅ , R ₅ and R ₆ may be linked to form a ring.)

  Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is preferable.

  Examples of the substituted or unsubstituted amino group include a substituted amino group such as a methylamino group, an ethylamino group, an n-propylamino group, a dimethylamino group, a diethylamino group, and a di-n-propylamino group. Group, acylamino group, sulfoamino group and the like. In addition, C2-C7 alkylcarbonyl groups such as acetyl, propiol, butyryl, isobutyl, valeryl, isovaler, pivaloyl, hexanoyl, heptanoyl, methoxycarbonyl, ethoxycarbonyl, n There are C2-C7 alkoxycarbonyl groups such as -propoxycarbonyl group, isopropoxycarbonyl group, n-butoxycarbonyl group, tert-butoxycarbonyl group, sec-butoxycarbonyl group. Further, an alkylsulfonyl group having 1 to 6 carbon atoms such as methylsulfonyl group, ethylsulfonyl group, n-propylsulfonyl group, isopropylsulfonyl group, n-butylsulfonyl group, sec-butylsulfonyl group; carboxylic acid ester group; carbamoyl group A sulfamoyl group; a sulfonate group; an aryl group having 6 to 16 carbon atoms which may have a substituent such as a phenyl group or a naphthyl group.

  Examples of the linear or branched alkyl group which may be substituted include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group, sec-butyl group, n-pentyl group, Examples thereof include linear or branched alkyl groups having 1 to 20 carbon atoms such as n-hexyl group, n-heptyl group, n-octyl group, n-decyl group, n-dodecyl group, n-octadecyl group, etc. A linear or branched alkyl group having 1 to 6 carbon atoms.

  Examples of the alkenyl group include linear or branched alkenyl groups having 2 to 20 carbon atoms such as vinyl, allyl, 1-propenyl, 2-pentenyl, 1,3-butadienyl, 2-octenyl, and 3-dodecenyl. , Preferably a linear or branched alkenyl group having 3 to 6 carbon atoms.

  Examples of the alkoxy group include methoxy, ethoxy, propoxy, isopropoxy, butoxy, 2-methoxyethoxy, pentyloxy, hexyloxy, octyloxy, decyloxy group, methoxymethyl group, methoxyethyl group, methoxypropyl group, methoxybutyl group, Carbon such as methoxyhexyl group, methoxyoctyl group, ethoxyethyl group, ethoxyethyl group, ethoxypropyl group, ethoxybutyl group, ethoxyhexyl group, ethoxyoctyl group, propoxymethyl group, propoxypropyl group, propoxyhexyl group, butoxyethyl group Examples thereof include linear or branched alkoxy groups having 1 to 20 carbon atoms, preferably linear or branched alkoxy groups having 1 to 6 carbon atoms.

  Examples of the aryl group include aryl groups having 6 to 18 carbon atoms such as phenyl group, tolyl group, xylyl group, mesityl group, cumenyl group, and naphthyl group, and preferably substituted or unsubstituted groups having 6 to 12 carbon atoms. An aryl group.

  Examples of the heterocycle include furan ring, pyrrole ring, thiophene ring, carbazole ring, pyridine ring, quinoline ring, isoquinoline ring, acridine ring, pyrimidine ring, pyrazine ring, phenazine ring, imidazole ring, triazole ring, oxazole ring, Examples include a thiazole ring, a thiadiazole ring, an oxadiazole ring, and the like.

  Examples of the acyl group include linear or branched alkenyl groups having 2 to 18 carbon atoms such as acetyl group, propionyl group, butyryl group, isobutyryl group, valeryl group, and isovaleryl group, preferably 3 to 9 carbon atoms. A linear or branched acyl group.

  Examples of the alkoxycarbonyl group include methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, isopropoxycarbonyl group, butoxycarbonyl group, 2-methoxyethoxycarbonyl group, pentyloxycarbonyl group, hexyloxycarbonyl group, octyloxycarbonyl group, Examples thereof include straight-chain or branched alkoxycarbonyl groups having 2 to 18 carbon atoms such as an undecyloxycarbonyl group, dodecyloxycarbonyl group, hexadecyloxycarbonyl group, and octadecyloxycarbonyl group, preferably a straight chain having 2 to 8 carbon atoms. A chain or branched alkoxycarbonyl group.

In the general formula (A), X is O, S, Se, N—R ₇ , C—R ₈ R ₉ (R ₇ , R ₈ , R ₉ are each independently a linear chain that may be substituted or A branched alkyl group, a halogenated alkyl group, a phenylalkyl group, an aryl group, an acyl group, a sulfonyl group, an alkoxycarbonyl group, and an alkylsulfonic acid group).

R ₇ , R ₈ and R ₉ are each independently an optionally substituted linear or branched alkyl group, halogenated alkyl group, phenylalkyl group, aryl group, acyl group, sulfonyl group, alkoxycarbonyl group. And an alkylsulfonic acid group, which are the same as R _{1 to} R ₆ in the general formula (A).

In the general formula (A), R ₃ and R ₄ , R ₄ and R ₅ and R ₅ and R ₆ may be linked to form a ring. Specific examples include a benzoindolenin ring and an α-naphthimidazole ring. , Β-naphthimidazole ring, α-naphthoxazole ring, β-naphthoxazole ring, α-naphthothiazole ring, β-naphthothiazole ring, α-naphthselenazole ring, β-naphthoselenazole ring.

  Although the preferable specific example (compound (1)-(36)) of the metal containing squarylium compound in this invention is given to the following, this invention is not limited to these.

  In the present invention, as a metal salt that forms a complex with a squarylium compound, various metal salts that form a complex can be used. Ni, Co, Zn, Cu, Pt, Ti, Al, V, Mn, Fe, Mo, W, Sn, Ru, Cr, and Pb salts are preferable, and Ni, Zn, Co, and Ti salts are particularly preferable in terms of solubility in various solvents, light resistance, and durability.

  The metal-containing squarylium compound of the present invention is prepared by synthesizing a squaric acid dichloride of the following general formula (C) or a squaric acid diester of the following general formula (D) by a known method, for example, a compound represented by the general formula (E): It can be obtained by reacting the squarylium compound obtained by the reaction with a metal salt compound in an organic solvent such as methanol, tetrahydrofuran, acetone, dioxane, DMF.

（式中、Ｒは炭素数１〜５の直鎖又は分岐のアルキル基を示す。）

(In the formula, R represents a linear or branched alkyl group having 1 to 5 carbon atoms.)

（式中、Ｒ_２〜Ｒ_７及びＸは一般式（Ａ）と同じ）

(Wherein R _{2 to} R ₇ and X are the same as those in the general formula (A))

  The optical recording medium of the present invention has a recording layer containing at least one metal-containing squarylium compound represented by the general formula (A) in the present invention on the substrate, and contains two or more different metal-containing squarylium compounds. You may let them.

  Further, the metal-containing squarylium compound of the present invention may form a J-type aggregate or an H-type aggregate.

  Since the metal-containing squarylium compound represented by the general formula (A) has absorption with intensity suitable for recording / reproducing with laser light in a short wavelength region of 350 nm to 530 nm, optical recording for recording / reproducing with a short wavelength laser is possible. It is extremely useful as a compound used in a medium.

  As a preferable configuration of the optical information recording medium of the present invention, a recording layer, a light reflection layer, and a protective layer are sequentially formed on a disc-like substrate on which pregrooves having a constant track pitch are formed. In addition, a recording layer and a light reflection layer are sequentially formed on a transparent disk-shaped substrate on which a light reflection layer, a recording layer, and a protective layer are sequentially formed, or a pre-groove having a constant track pitch is formed. A configuration in which the two laminated bodies are joined so that the recording layers are directed inward is exemplified. Hereinafter, the optical recording medium will be described in detail.

  The material of the substrate in the optical recording medium of the present invention can be arbitrarily selected from various materials used as a substrate of a conventional optical information recording medium. Examples of the substrate material include glass, polycarbonate resin, acrylic resin such as polymethyl methacrylate, polyvinyl chloride resin such as polyvinyl chloride resin and vinyl chloride copolymer, epoxy resin, amorphous polyolefin resin, and polyester resin. Among these materials, injection molded polycarbonate resin is preferable from the viewpoints of moisture resistance, dimensional stability and price. A resin substrate or a resin layer may be provided in contact with the recording layer, and guide grooves or pits for recording / reproducing light may be provided on the resin substrate or resin layer. When the guide groove has a spiral shape, the groove pitch is preferably about 0.5 to 1.2 μm.

  The recording layer is formed by a generally used thin film forming method such as a vapor phase method such as a vacuum deposition method, a sputtering method, or a CVD method, a liquid phase method such as a doctor blade method, a cast method, a spin coating method, or an immersion method. However, the spin coating method is preferable from the viewpoint of mass productivity and cost.

  The solvent for the liquid phase method is not particularly limited as long as it does not attack the substrate. For example, esters such as butyl acetate, ethyl lactate and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane and chloroform; amides such as dimethylformamide; Hydrocarbons; ethers such as dibutyl ether, diethyl ether, tetrahydrofuran, dioxane; alcohols such as ethanol, n-propanol, isopropanol, n-butanol, diacetone alcohol; fluorines such as 2,2,3,3-tetrafluoropropanol Solvents: Glycol agents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether And the like Le acids. The above solvents can be used alone or in combination of two or more in consideration of the solubility of the compound used.

  The thickness of the recording layer is generally in the range of 20 to 500 nm, preferably in the range of 30 to 300 nm, and more preferably in the range of 50 to 150 nm.

  The recording layer may use a singlet oxygen quencher in order to improve the light resistance of the recording layer. Examples of singlet quenchers include transition metal chelate complexes such as acetylacetonate chelate, bisphenyldithiol, salicylaldehyde oxime, and bisdithio-α-diketone, aromatic nitroso compounds, aminium compounds, iminium compounds, and bisiminium compounds.

  A light reflection layer may be formed on the recording layer, and the thickness thereof is preferably 50 to 300 nm. As a material of the light reflecting layer, a material having a sufficiently high reflectance at the wavelength of the reproduction light, for example, Au, Al, Ag, Cu, Ti, Cr, Ni, Pt, Ta, and Pd metal alone or in an alloy is used. It is possible to use. Among these, Au, Al, and Ag have high reflectivity and are suitable as the material for the reflective layer. The reflective layer can be formed on the substrate or the recording layer, for example, by vapor deposition, sputtering or ion plating of the light reflective material. The thickness of the light reflection layer is generally in the range of 10 to 300 nm, preferably in the range of 50 to 200 nm.

The material for the protective layer formed on the reflective layer is not particularly limited as long as it protects the reflective layer from external force. Specifically, examples of the organic material include a thermoplastic resin, a thermosetting resin, an electron beam curable resin, and a UV curable resin. Examples of the inorganic material include SiO ₂ , Si ₃ N ₄ , MgF ₂ , SnO _{2 and the} like.

  A protective layer using a thermoplastic resin or a thermosetting resin is formed by applying a coating solution obtained by dissolving the resin in a suitable solvent to the surface of the substrate on which the recording layer or the light reflecting layer is formed, and drying. Can do.

  A protective layer using a UV curable resin is obtained by applying a coating solution dissolved in the resin alone or in an appropriate solvent to the surface of a substrate on which a recording layer or a light reflecting layer is formed, and then irradiating and curing the UV light. Can be formed. As the UV curable resin, for example, acrylate resins such as urethane acrylate, epoxy acrylate, and polyester acrylate can be used. These materials may be used alone or in combination, and a single layer or a multilayer film may be formed.

  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 generally in the range of 0.1 to 100 μm, but is preferably 3 to 30 μm in the present invention.

  The laser beam used for the optical recording medium of the present invention is selected to have a short wavelength region capable of high-density recording, preferably a blue-violet semiconductor laser beam having an oscillation wavelength of 350 to 430 nm, more preferably 390 to 390 nm. Blue-violet semiconductor laser light having an oscillation wavelength of 420 nm is used.

  Recording on the optical recording medium of the present invention is performed by irradiating a recording layer provided on both sides or one side of the substrate with laser light focused to about 0.4 to 0.6 μm. In the portion irradiated with laser light, thermal deformation of the recording layer, such as decomposition, heat generation, and dissolution, due to absorption of laser light energy occurs, optical characteristics change, and recording pits are formed. The recorded information is reproduced by irradiating the playback laser beam and detecting the difference in reflectance between the part where the optical characteristics of the recording layer have changed (recorded part) and the part that has not changed (unrecorded part). Is done.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, “part” represents “part by mass”.

Example 1
(1) 9.0 parts of 3,4-dibutoxy-cyclobut-3-ene-1,2-dione, 1-ethyl-2,3,3-trimethyl-benzoindolenium in a three-necked flask equipped with a condenser Iodide 12.0 parts and triethylamine 6.0 parts were added, ethanol 300 parts was added thereto, and the mixture was stirred at room temperature for 6 hours. After completion of the reaction, the reaction mixture was cooled to room temperature, and the precipitated solid was collected by filtration under reduced pressure. After recrystallization from acetone and drying under reduced pressure, the squarylium intermediate 3- (1-ethyl-3,3-dimethyl-1,3-dihydro-indole-2-ylidenemethyl) -4-butoxy-cyclobut-3-ene- 8.5 parts of 1,2-dione were obtained. Next, 8.5 parts of the obtained squarylium intermediate and 100 parts of an acetic acid: water = 4: 1 mixed solution were put into a three-necked flask equipped with a cooling tube, and the mixture was heated and stirred at 100 ° C. for 2 hours. After the reaction, the reaction mixture was cooled to room temperature, and the precipitated solid was collected by filtration under reduced pressure. After washing with water and drying under reduced pressure, 3- (1-ethyl-3,3-dimethyl-1,3-dihydro-indole-2-ylidenemethyl) -4-hydroxy-cyclobut-3-ene-1,2-dione 7.0 parts were obtained.

  (2) In a three-necked flask equipped with a condenser, 3- (1-ethyl-3,3-dimethyl-1,3-dihydro-indole-2-ylidenemethyl) -4-hydroxy-cyclobut-3-ene- 4.1 parts of 1,2-dione and 2.0 parts of nickel acetate tetrahydrate were added, and 100 parts of THF was added thereto, followed by heating and stirring at 60 ° C. for 4 hours. After the reaction, the reaction mixture was cooled to room temperature, and the precipitated solid was collected by filtration under reduced pressure. After washing with water and drying under reduced pressure, the squarylium compound (1) 3- (1-ethyl-3,3-dimethyl-1,3-dihydro-indole-2-ylidenemethyl) -4-hydroxy-cyclobut-3- 5.8 parts of an en-1,2-dione-nickel complex were obtained.

(Example 2)
(1) A squarylium intermediate obtained by the same operation as in Example 1 using 1-ethyl-3,3-dimethyl-5-hydroxy-benzoindolenium iodide as a starting material in a three-necked flask equipped with a condenser. 6.5 parts of 3- (1-ethyl-5-hydroxy-3,3-dimethyl-1,3-dihydro-indole-2-ylidenemethyl) -4-butoxy-cyclobut-3-ene-1,2-dione 100 parts of 2M ammonia-methanol solution was added and stirred and heated at 40 ° C. for 8 hours. After the reaction, the mixture was cooled to room temperature, and the precipitated solid was collected by filtration under reduced pressure. After washing with water and drying under reduced pressure, 3-amino-4- (1-ethyl-5-hydroxy-3,3-dimethyl-1,3-dihydro-indole-2-ylidenemethyl) -cyclobut-3-ene-1 , 2-dione 4.8 parts.

(2) 3-amino-4- (1-ethyl-5-hydroxy-3,3-dimethyl-1,3-dihydro-indole-2-ylidenemethyl) -cyclobuta-3 in a three-necked flask equipped with a condenser -4.8 parts of ene-1,2-dione and 2.5 parts of zinc acetate / hydrate were added, and 200 parts of THF was added thereto, followed by heating and stirring at 60 ° C for 4 hours. After the reaction, the reaction mixture was cooled to room temperature, and the precipitated solid was collected by filtration under reduced pressure. After washing with water and drying under reduced pressure, the squarylium compound (7) 3-amino-4- (1-ethyl-5-hydroxy-3,3-dimethyl-1,3-dihydro-indole-2-ylidenemethyl)- 5.8 parts of cyclobut-3-ene-1,2-dione-zinc complex were obtained.

(Example 3)
3- (3-ethyl-3H) which is a squarylium compound (13) in the same manner as in Example 1 except that in Example 1, the amount was changed to 5.0 parts of 3-ethyl-2-methyl-thiazolium iodide. -Benzothiazol-2-ylidenemethyl) -4-hydroxy-cyclobut-3-ene-1,2-dione-nickel complex was obtained.

Example 4
3-amino-4- (2) which is a squarylium compound (20) in the same manner as in Example 2 except that in Example 2, 5.0 parts of 2,3-dimethyl-3H-naphthothiazolium iodide was changed. A 3-methyl-3H-naphtho [2,1-d] thiazol-2-ylidenemethyl) -cyclobut-3-ene-1,2-dione-zinc complex was obtained.

(Example 5)
In Example 1, 3-hydroxy-4- (2), which is a squarylium compound (25), was used in the same manner as in Example 1 except that 5.0 parts of 2,3-dimethyl-oxazolium iodide and cobalt salt were used. 3-Methyl-3H-benzoxazole-2-ylidenemethyl) -cyclobut-3-ene-1,2-dione-cobalt complex was obtained.

(Example 6)
(1) The same method as in Example 1 except that 6- (bis-trifluoromethyl-amino) -2-methyl-3-isobutyl-benzoselenazolium iodide was used as a starting material in a three-necked flask equipped with a condenser. Operationally obtained squarylium intermediate 3- [6- (bis-trifluoromethyl-amino) -3- (3-methyl-butyl) -3H-benzoselenazol-2-ylidenemethyl] -4-butoxy-cyclobuta-3 -6.2 parts of ene-1,2-dione and 8.0 parts of trifluoromethanesulfonic anhydride were added and stirred and heated at 40 ° C for 8 hours. After the reaction, the mixture was cooled to room temperature, and the precipitated solid was collected by filtration under reduced pressure. After washing with water and drying under reduced pressure, N- {2- [6- (bis-trifluoromethyl-amino) -3- (3-methyl-butyl) -3H-benzoselenazol-2-ylidenemethyl] -3, 4.8 parts of 4-dioxo-cyclobut-1-enyl} C, C, C-trifluoro-methanesulfonamide were obtained.

  (2) N- {2- [6- (bis-trifluoromethyl-amino) -3- (3-methyl-butyl) -3H-benzoselenazol-2-ylidenemethyl] in a three-necked flask equipped with a condenser ] -3,4-dioxo-cyclobut-1-enyl} C, C, C-trifluoro-methanesulfonamide 4.8 parts, zinc acetate dihydrate 2.5 parts, and THF 200 parts. The mixture was stirred at 60 ° C. for 4 hours. After the reaction, the reaction mixture was cooled to room temperature, and the precipitated solid was collected by filtration under reduced pressure. After washing with water and drying under reduced pressure, the squarylium compound (35) N- {2- [6- (bis-trifluoromethyl-amino) -3- (3-methyl-butyl) -3H-benzoselenazole- There were obtained 5.3 parts of 2-ylidenemethyl] -3,4-dioxo-cyclobut-1-enyl} C, C, C-trifluoro-methanesulfonamide-zinc complex.

(Physical properties of compounds)
The maximum absorption wavelength (hereinafter abbreviated as “λmax”) in acetone of the metal-containing squarylium compound obtained in Example 1 was 416 nm, and the molar extinction coefficient at λmax was 416 nm. (Hereinafter abbreviated as “ε”) was 8.8 × 10 ⁴ M ⁻¹ cm ⁻¹ . As a result of differential thermal analysis (Seiko Instruments, TG / DTA6300), the decomposition point was 325 ° C. The obtained metal-containing squarylium compound was dissolved in tetrafluoropentanol to make 2 wt%, and a thin film was formed on a flat polycarbonate disk by spin coating. The absorption spectrum of this coating film was measured by the transmission method, and as shown in FIG. 2, λmax was 422 nm. For reference, the absorption spectrum of the solution measured by the transmission method is shown in FIG.

  Table 2 shows the results of Examples 1 to 6 measured in the same manner. In these examples, ε was calculated on the assumption that metal: squarylium = 1: 2.

(Comparative Examples 1 and 2)
As a comparative example, the characteristics of the squarylium compound before metal complexation obtained in Example 1 and Example 3 were measured in the same manner as in the example, and the results are shown in Table 2.

  As shown in Table 2, the metal-containing squarylium compounds of Examples 1 to 6 of the present invention have light absorption in the wavelength region of 400 to 500 nm and have a high molar extinction coefficient. In Comparative Example 2, the molar absorption coefficient was small.

(Light resistance test of coating film)
The coating films of Examples 1 to 6 and Comparative Examples 1 and 2 were irradiated for a predetermined time in a 320 W xenon lamp at 63 ° C. The initial absorbance at λmax was taken as 100%, and the percentage of absorbance after a predetermined time was calculated as the dye residual ratio. These results are shown in Table 3.

  As shown in Table 3, the coating films of Examples 1 to 6 of the present invention have high light resistance with a dye residual ratio exceeding 80% even after 8 hours of irradiation, but Comparative Example 1 and Comparative Example 2 After 1 hour of irradiation, the dye residual ratio changed to a maximum of 36% and the squarylium compound was changed, and the light resistance could not be maintained.

UV-Vis absorption spectrum of the solution of Example 1 UV-Vis absorption spectrum of the coating film of Example 1

Claims (3)

The squarylium compound represented by the following general formula (A) was selected from the group consisting of Ni, Co, Zn, Cu, Pt, Ti, Al, V, Mn, Fe, Mo, W, Sn, Ru, Cr, and Pb. A metal- containing squarylium compound, which is a metal complex composed of at least one metal .

(In the formula, R ₁ represents a hydroxyl group, an amino group, a sulfonamide group, and R ₂ represents an optionally substituted linear or branched alkyl group, halogenated alkyl group, cyanoalkyl group, alkoxy group, phenylalkyl group. Represents an alkylsulfonic acid group, and R ₃ , R ₄ , R ₅ and R ₆ each independently represent a hydrogen atom, a halogen atom, or a substituted or unsubstituted amino group, hydroxy group, cyano group, nitro group, amino group Group, a sulfo group, or an optionally substituted linear or branched alkyl group, alkenyl group, alkoxy group, aryl group, heterocycle, acyl group, or alkoxycarbonyl group (provided that R ₃ and R ₄ , R ₄ and R ₅ , R ₅ and R ₆ may be linked to form a ring), X is O, S, Se, N—R ₇ , C—R ₈ R ₉ (R ₇ , R ₈ , R ₉ is each Independently, an optionally substituted linear or branched alkyl group, halogenated alkyl group, phenylalkyl group, aryl group, acyl group, sulfonyl group, alkoxycarbonyl group, and alkylsulfonic acid group are represented.)) In an optical recording medium in which a recording layer capable of writing and / or reading information with a laser beam is formed on a substrate, the recording layer contains at least one metal-containing squarylium compound according to claim 1. An optical recording medium. The optical recording medium according to claim 2 , wherein information is recorded and / or reproduced by a laser beam selected from a wavelength region of a wavelength of 350 nm to 530 nm.

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