JP2004098673A - Optical recording medium and optical recording method - Google Patents

Abstract

（式中、Ｒ₁ないしＲ₆は各々独立に水素原子、置換されてもよい直鎖または分岐のアルキル基を表す。ｋおよびｎは各々独立に０〜２の整数を表し、かつ０≦ｋ＋ｎ≦４である。ｌおよびｍは各々独立に０または１を表し、かつ１≦ｌ＋ｍ≦２である。環Ａおよび環Ｂは各々独立に、任意の置換基を有していてもよい芳香族環を表す。但し、該任意の置換基同士が結合して環を形成していてもよい。）
【選択図】　なし



PROBLEM TO BE SOLVED: To provide an organic dye-based optical recording medium capable of recording / reproducing with a shorter wavelength blue laser.
SOLUTION: An optical recording medium provided with a recording layer capable of recording or reproducing information by a laser on a substrate, wherein the recording layer contains a compound represented by the following general formula (1).

(Wherein, R ₁ to R ₆ each independently represent a hydrogen atom, a linear or branched alkyl group which may be substituted. K and n each independently represent an integer of 0 to 2, and 0 ≦ k + n ≤ 4. l and m each independently represent 0 or 1, and 1 ≤ l + m ≤ 2. Ring A and ring B each independently represent an aromatic group optionally having any substituent Represents a ring, provided that the arbitrary substituents may be bonded to each other to form a ring.)
[Selection diagram] None

Description

The present invention relates to an optical recording medium using an organic dye for a recording layer and an optical recording method thereof, and more particularly, to an optical recording medium recordable and reproducible by a blue laser and an optical recording method thereof.

At present, various optical recording media such as a CD-R / RW, a DVD ± R / RW, and an MO can store a large amount of information and are easily accessed at random. It is widely recognized and widely used as a device. Among these, organic dye-based optical recording media represented by CD-R and DVD-R are considered to be superior in that they are inexpensive and easy to manufacture.

Further, it is desired to increase the recording density of a medium due to an increase in the amount of information to be handled. In recent years, an optical recording medium capable of high-density recording and reproduction using a laser having a short oscillation wavelength (a so-called short-wavelength laser) such as a blue laser, which has been remarkably developed, has been proposed (for example, see Patent Document 1).
JP 2000-044232 A

Generally, in the case of an optical recording medium commercially available as a CD-R, a DVD-R, or the like, for example, the CD-R is suitable for recording / reproducing by a laser beam having a wavelength of about 780 nm, and the DVD-R is a wavelength of 600 to 780 nm. It is designed to be suitable for recording / reproducing with a laser beam of about 700 nm. Such a recording medium suitable for optical recording / reproducing using a laser beam having a relatively long wavelength has a problem that when recording / reproducing using a laser having a shorter wavelength, the reflectivity is low and recording / reproducing cannot be performed. have. The blue laser usually refers to a laser having a wavelength of about 350 nm to 530 nm.

The object of the present invention is to provide an organic dye-based optical recording medium that can be recorded / reproduced by a blue laser having a shorter wavelength.

The present inventors have conducted various studies on organic dyes having high sensitivity to a blue semiconductor laser and found that the compound represented by the general formula (1) can be used in a recording layer of an optical recording medium corresponding to a blue semiconductor laser. And arrived at the present invention.

That is, the gist of the present invention is that in an optical recording medium provided with a recording layer capable of recording or reproducing information by laser on a substrate, the recording layer contains a compound represented by the following general formula (1); And an optical recording method comprising recording information on the optical recording medium using a laser beam having a wavelength of 350 nm to 530 nm.

(Wherein, R ₁ to R ₆ each independently represent a hydrogen atom, a linear or branched alkyl group which may be substituted. K and n each independently represent an integer of 0 to 2, and 0 ≦ k + n ≤ 4. l and m each independently represent 0 or 1, and 1 ≤ l + m ≤ 2. Ring A and ring B each independently represent an aromatic group optionally having any substituent Represents a ring, provided that the arbitrary substituents may be bonded to each other to form a ring.)

Since the solution containing the compound of the present invention can form a coating film having an absorption suitable for recording and reproduction by short-wavelength laser light and has excellent film formability, the recording layer using the compound of the present invention is excellent. Is useful as an optical recording medium for recording and reproduction corresponding to a short wavelength laser.

Hereinafter, the present invention will be described in detail.

化合物 The compound used in the present invention is preferably a dye compound which has an appropriate absorption in the blue light region of 350 to 530 nm and is suitable for recording with a blue laser. In the present invention, a dye compound represented by the general formula (1) is used as such a dye. Hereinafter, the compound represented by Formula (1) will be described.

In the general formula (1) representing the compound according to the present invention, R ₁ to R ₆ each independently represent a hydrogen atom, a linear or branched alkyl group which may be substituted. R ₁ to R ₆ are preferably each independently a hydrogen atom or a linear alkyl group which may be substituted, and particularly preferably each independently a hydrogen atom or an unsubstituted linear alkyl chain having 1 to 3 carbon atoms. It is. Specifically, it is a methyl group, an ethyl group, or a propyl group.

Ｋ Also, k, l, m, and n each represent the number of unsaturated bonds. k and n represent the number of C = C double bonds, and l and m represent the number of C = N double bonds. k and n each independently represent an integer of 0 to 2, and 0 ≦ k + n ≦ 4. l and m each independently represent 0 or 1, and 1 ≦ l + m ≦ 2.

Here, the above-mentioned general formula (1) is represented by the following general formula when ring A and ring B are represented by a benzene ring for convenience (the same applies to the following description).

In the general formula, specific examples of the structure in which k and n are changed without changing l and m are shown below (provided that R ₁ ′ to R ₆ ′ are each independently the above R _1). To R ₆ ).

  The values of k and n are determined by the structures of rings A and B, the types of substituents on the rings, and the like. Usually, preferably, k and n each independently represent 0 or 1, and 0 ≦ k + n ≦ 2 It is.

On the other hand, specific examples of the structure in the case where l and m are changed without changing k and n in the above general formula are shown below.

The values of l and m are determined by the structures of the rings A and B, the types of substituents on the rings, and the like. Usually, preferably, l and m each independently represent 0 or 1, and 1 ≦ l + m ≦ 2 It is. More preferably, l + m = 1.

In the general formula (1), ring A and ring B each independently represent an aromatic ring which may have an arbitrary substituent. However, the arbitrary substituents may be bonded to each other to form a ring. Examples of the aromatic ring include, but are not limited to, aromatic hydrocarbon rings such as a benzene ring and a naphthyl ring, and aromatic heterocycles such as a furan ring, a pyridine ring, and a quinoline ring.

に お い て In the present invention, it is preferable to use a 5- to 6-membered single ring or a 2- to 3-condensed ring thereof as the aromatic ring. The structure of the monocyclic 5- to 6-membered ring or the condensed ring thereof is not particularly limited, and examples thereof include an aromatic ring structure shown below.

特 に Among them, particularly preferred are a hydrocarbon ring and a heterocyclic structure, which is a 5- or 6-membered monocyclic or 2-condensed ring.

In the present invention, the aromatic ring represented by ring A or ring B may have a substituent. The substituents used individually may be arbitrary and may be further substituted. However, if too large, the basic skeleton is unexpectedly affected, so that the molecular weight of the substituent is usually 1,000 or less. There is no particular lower limit, and it is 1 or more.

Examples of the optional substituent include the following. Methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-heptyl group, etc. Alkyl group; cycloalkyl group having 3 to 18 carbon atoms which may be substituted such as cyclopropyl group, cyclopentyl group, cyclohexyl group and adamantyl group; carbon atom which may be substituted such as vinyl group, propenyl group and hexenyl group 2 A linear or branched alkenyl group having from 18 to 18; a cycloalkenyl group having 3 to 18 carbon atoms which may be substituted such as a cyclopentenyl group or a cyclohexenyl group; a 2-thienyl group, a 2-pyridyl group, a 4-piperidyl group; A heterocyclic group which may be substituted such as a morpholino group; an aryl group having 6 to 18 carbon atoms which may be substituted such as a phenyl group, a tolyl group, a xylyl group, a mesityl group; a benzyl group; An aralkyl group having 7 to 20 carbon atoms which may be substituted, such as a netyl group; substitution of a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, a tert-butoxy group, etc. A linear or branched alkoxy group having 1 to 18 carbon atoms which may be used;
A linear or branched alkenyloxy group having 3 to 18 carbon atoms which may be substituted, such as a propenyloxy group, a butenyloxy group, and a pentenyloxy group; a methylthio group, an ethylthio group, an n-propylthio group, an n-butylthio group, and a sec- Examples thereof include a linear or branched alkylthio group having 1 to 18 carbon atoms which may be substituted, such as a butylthio group and a tert-butylthio group.

Other specific examples include a halogen atom such as a fluorine atom, a chlorine atom and a bromine atom; a nitro group; a nitroso group; a cyano group; an isocyano group; a cyanato group; an isocyanato group; a thiocyanato group; an isothiocyanato group; a mercapto group; hydroxyamino group; a formyl group; a sulfonic group; a carboxyl group; an acyl group represented by -COR _7, amino group represented by -NR ₈ R _9, an acylamino group represented by -NHCOR _10, in -NHCOOR ₁₁ represented by carbamate group, carboxylate group represented by -COOR _12, acyloxy group represented by -OCOR _13, a carbamoyl group represented by -CONR ₁₄ R _15, sulphonyl represented by -SO ₂ R ₁₆ group, a sulfamoyl group represented by -SO ₂ NR ₁₇ R _18, sulfonic acid ester group represented by -SO ₃ R _19, -N Sulfonamido groups represented by SO ₂ R ₂₀ can be mentioned.

位置 The positions of these substituents are not particularly limited, and the number of substituents can be in an arbitrary range. When it has a plurality of substituents, they may be the same or different.

Here, it represents _{R 7, R 10, R 11} , R 12, R 13, R 16, R 19, R 20 is optionally substituted hydrocarbon group or an optionally substituted heterocyclic group,, R ₈ , R ₉ , R ₁₄ , R ₁₅ , R ₁₇ , and R ₁₈ represent any of a hydrogen atom, an optionally substituted hydrocarbon group, and an optionally substituted heterocyclic group.

The hydrocarbon group represented by the R ₇ to R _20, represent linear or branched alkyl group, a cyclic alkyl group, straight or branched alkenyl group, a cyclic alkenyl group, an aralkyl group, an aryl group. Among them, preferably, a straight-chain or branched alkyl having 1 to 18 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group and an n-heptyl group. Group, cyclopropyl group, cyclopentyl group, cyclohexyl group, cyclic alkyl group having 3 to 18 carbon atoms such as adamantyl group, vinyl group, propenyl group, linear or branched alkenyl group having 2 to 18 carbon atoms such as hexenyl group, C3-C18 cyclic alkenyl groups such as cyclopentenyl group and cyclohexenyl group, C7-C20 aralkyl groups such as benzyl group and phenethyl group, phenyl group, tolyl group, xylyl group and mesityl group; And 6-18 aryl groups.

ア リ ー ル The aryl group portion of these groups may be further substituted with the same substituents as the rings A and B may have. Further, the alkyl chain portion of these groups may be further substituted with a substituent described below.

The heterocyclic group represented by R ₇ to R ₂₀ is 4-piperidyl group, morpholino group, 2-morpholinyl group, be saturated heterocyclic ring such as piperazyl group, 2-furyl group, 2-pyridyl, 2-thiazolyl Or an aromatic heterocyclic ring such as a 2-quinolyl group. These may include a plurality of hetero atoms, may further have a substituent, and may be in any position. Preferable examples of the heterocyclic ring include a 5- to 6-membered saturated heterocyclic ring, a 5- to 6-membered monocyclic ring and an aromatic heterocyclic ring having two condensed rings thereof.

Specifically, an optionally substituted acyl group represented by -COR ₇ , an optionally substituted amino group represented by -NR ₈ R ₉ , and a substituted amino group represented by -NHCOR ₁₀ also acylamino group, an optionally substituted carbamate group represented by -NHCOOR _11, -C
Optionally substituted carboxylic acid ester group represented by OOR _12, optionally substituted acyloxy group, -CONR ₁₄ optionally substituted carbamoyl group represented by R ₁₅ is represented by -OCOR ₁₃ , optionally substituted sulfonyl group represented by -SO ₂ R _16, -S
An optionally substituted sulfamoyl group represented by O ₂ NR ₁₇ R ₁₈ , an optionally substituted sulfonic acid ester group represented by —SO ₃ R ₁₉ , and a substituted sulfonic acid ester group represented by —NHSO ₂ R ₂₀ And the like.

Acyl group (-COR ₇ )

Amino groups (-NR ₈ R ₉₎

Acylamino group (—NHCOR ₁₀ )

Carbamate group (-NHCOOR ₁₁ )

Carboxylic acid ester group (-COOR ₁₂ )

Acyloxy group (—OCOR ₁₃ )

Carbamoyl group (-CONR ₁₄ R ₁₅ )

A sulfonyl group (-SO ₂ R ₁₆₎

Sulfamoyl (-SO ₂ NR ₁₇ R ₁₈₎

Sulfonic acid ester group (-SO ₃ R ₁₉₎

Sulfonamide group (-NHSO ₂ R ₂₀₎

A linear or branched alkyl group, a cyclic alkyl group, a linear or branched alkenyl group, a cyclic alkenyl group, a linear or branched alkoxy group, a straight or branched alkylthio group which the ring A and the ring B may have, and alkyl chain moiety of the alkyl group represented by R ₇ to R _20, which may have a substituent, examples of the substituent groups include those such as the following.

A methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, a sec-butoxy group, an alkoxy group having 1 to 10 carbon atoms such as a tert-butoxy group;
An alkoxyalkoxy group having 2 to 12 carbon atoms such as an ethoxymethoxy group, a propoxymethoxy group, an ethoxyethoxy group, a propoxyethoxy group, a methoxybutoxy group; a methoxymethoxymethoxy group, a methoxymethoxyethoxy group, a methoxyethoxymethoxy group, a methoxymethoxyethoxy group , An alkoxyalkoxyalkoxy group having 3 to 15 carbon atoms such as an ethoxyethoxymethoxy group; an aryl group having 6 to 12 carbon atoms such as a phenyl group, a tolyl group, and an xylyl group (these may be further substituted with any substituents) Good)); aryloxy groups having 6 to 12 carbon atoms such as phenoxy group, tolyloxy group, xylyloxy group, and naphthyloxy group; and alkenyloxy groups having 2 to 12 carbon atoms such as allyloxy group and vinyloxy group.

Further, as other substituents, heterocyclic groups such as 2-thienyl group, 2-pyridyl group, 4-piperidyl group, morpholino group, etc .; cyano group; nitro group; hydroxyl group; amino group; N, N-dimethylamino group An alkylamino group having 1 to 10 carbon atoms such as N, N, N-diethylamino group; an alkylsulfonylamino group having 1 to 6 carbon atoms such as methylsulfonylamino group, ethylsulfonylamino group, n-propylsulfonylamino group; fluorine atom , A chlorine atom, a halogen atom such as a bromine atom; a carboxyl group, a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, an isopropoxycarbonyl group, an alkoxycarbonyl group having 2 to 7 carbon atoms such as n-butoxycarbonyl; methyl Carbonyloxy, ethylcarbonyloxy, n-propylcarbonyloxy, isopro Alkylcarbonyloxy groups having 2 to 7 carbon atoms, such as carbonylcarbonyl group and n-butylcarbonyloxy group; methoxycarbonyloxy group, ethoxycarbonyloxy group, n-propoxycarbonyloxy group, isopropoxycarbonyloxy group, n-butoxy Examples thereof include an alkoxycarbonyloxy group having 2 to 7 carbon atoms such as a carbonyloxy group.

The substituents that the ring A and the ring B may have may be bonded to each other to independently form a condensed ring. The condensed ring formed by these may be a saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring containing one or more hetero atoms. The number of members of the cyclic structure is not particularly limited, but a hydrocarbon ring and a heterocyclic ring are preferably a 5- to 7-membered ring, and particularly preferably a 5- to 6-membered ring.

R ₈ and R ₉ , R ₁₄ and R ₁₅ , and R ₁₇ and R ₁₈ may be mutually bonded to form a ring structure independently. The ring formed by these may be a saturated or unsaturated hydrocarbon ring or a saturated or unsaturated heterocyclic ring containing one or more hetero atoms. The number of members of the cyclic structure is not particularly limited, but a hydrocarbon ring and a heterocyclic ring are preferably a 5- to 7-membered ring, and particularly preferably a 5- to 6-membered ring.

好 ま し い The preferred ring structures of these are shown below.

縮合 The position and number of these condensation positions are not limited as long as they are between adjacent substituents. Further, these condensed rings may have the same substituent as ring A or ring B may have.

Next, a more preferable structure of the compound represented by the general formula (1) in the present invention will be described.

Among the substituents which the aromatic ring represented by ring A and ring B may have, more preferred substituents include the following. Methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, n-heptyl group, etc. Alkyl group; a methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, tert-butoxy group, etc. Alkoxy group; linear or branched alkylthio group having 1 to 18 carbon atoms which may be substituted, such as methylthio group, ethylthio group, n-propylthio group, n-butylthio group, sec-butylthio group, tert-butylthio group; fluorine a nitro group; a cyano group; a mercapto group; hydroxy group; atom, a chlorine atom, a halogen atom such as a bromine atom -NR ₈ amino group represented by R _9, an acylamino group represented by -NHCOR _10, -NHCOO Carbamate group represented by _11, a carboxylic acid ester group represented by -COOR _12, acyloxy group represented by -OCOR _13, -CONR ₁₄ carbamoyl group represented by R _15; adjacent substituents are bonded to each other And a saturated heterocyclic group formed by condensation.

Among them, particularly preferred substituents are those having 1 carbon atom which may be substituted such as methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group and n-heptyl group. To 18 linear or branched alkyl groups; methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, tert-butoxy group, etc. A straight-chain or branched alkoxy group having 1 to 18 carbon atoms, such as a methylthio group, an ethylthio group, an n-propylthio group, an n-butylthio group, a sec-butylthio group, a tert-butylthio group; chain or branched alkylthio group; a mercapto group; hydroxy group; -NR ₈ amino group represented by R _9, an acylamino group represented by -NHCOR _10; saturated adjacent substituent is fused form combined with each other A heterocyclic group.

結合 As the bonding position of the substituent, when ring A or ring B is a benzene ring, it is preferable that the substituent has a substituent para to the unsaturated bond. When ring A or ring B is a 5-membered heterocyclic ring, the unsaturated bond and the substituent are preferably bonded at the 2-position and / or 5-position.

に お い て In the present invention, preferred examples of the compound represented by the general formula (1) include the following.

The compound represented by the general formula (1) has a maximum absorption wavelength (λmax) when formed into a thin film.
Using a blue semiconductor laser, such as that many exist in a relatively short wavelength region of about 320 to 400 nm, the peak shape of the absorption spectrum is relatively sharp, and the molar extinction coefficient ε is 20,000 or more. It has excellent optical characteristics for recording and reproducing. Here, the maximum absorption wavelength usually means the maximum absorption wavelength at a wavelength of 300 nm or more. Further, since it has excellent thin film forming properties in a state of being dissolved or dispersed in a solvent, it satisfies the chemical properties required when producing an optical recording medium. Therefore, the compound represented by the general formula (1) can be extremely suitably used for a recording layer of an optical recording medium that performs recording and reproduction using a blue semiconductor laser.

The compound which can be used in the recording layer of the optical recording medium of the present invention has an optical density OD in a solution state.
80 or more, high solubility in commonly used harmless and inexpensive solvents, good quality film formation when forming thin films (no crystallization during film formation), solution state Further, it is more preferable to satisfy that storage stability in a thin film state is good.

記録 In the recording layer of the optical recording medium of the present invention, the extinction coefficient (imaginary part of the complex refractive index) k at the wavelength of the recording and reproducing light is preferably 0 to 0.20. Further, the refractive index (real part of the complex refractive index) n is preferably 1.8 or more.

Next, the optical recording medium of the present invention will be described.

光学 The optical recording medium of the present invention comprises at least a substrate and a recording layer containing the compound represented by the general formula (1). Further, an undercoat layer, a reflective layer, a protective layer, and the like may be provided as necessary.

例 An example of a preferable layer configuration is a medium having a high reflectance in which a recording layer is provided on a substrate, and a reflective layer and a protective layer are further laminated on the recording layer in this order. In this case, recording and reproduction of information are performed by irradiating a laser beam from the substrate side (medium structure example 1).

Hereinafter, the optical recording medium of the present invention will be described using a medium having such a structure (medium structure example 1) as an example. In the following description, for convenience of explanation, the side on which the protective layer is present at the time of lamination and the side on which the substrate is present are regarded as upper and lower, respectively, and each surface of each layer corresponding to these directions is referred to as the upper surface of each layer. And the lower surface.

The substrate in the optical recording medium of the present invention may be made of various materials as long as it is basically transparent at the wavelengths of recording light and reproducing light. Specifically, for example, a resin substrate such as an acrylic resin, a methacrylic resin, a polycarbonate resin, a polyolefin resin (particularly, an amorphous polyolefin), a polyester resin, a polystyrene resin, an epoxy resin, a glass substrate, a glass substrate A substrate on which a resin layer made of a radiation curable resin such as a photocurable resin is provided.

Above all, a substrate made of injection-molded polycarbonate is preferable from the viewpoints of high productivity, cost, and moisture absorption resistance. Further, from the viewpoints of chemical resistance and moisture absorption resistance, a substrate made of amorphous polyolefin is preferable. Further, from the viewpoint of high-speed response, a glass substrate is preferable.

When a resin substrate is used, or when a substrate provided with a resin layer on the side (upper side) in contact with the recording layer is used, a guide groove for recording / reproducing light is formed on the upper surface of the resin substrate or the resin layer. And pits may be formed. Examples of the shape of the guide groove include a concentric shape and a spiral shape based on the center of the optical recording medium. When a spiral guide groove is formed, the groove pitch is preferably about 0.2 to 1.2 μm.

(4) A recording layer containing the compound represented by the general formula (1) is formed directly on the substrate or on an undercoat layer or the like provided on the substrate as necessary. Examples of the method for forming the recording layer include various commonly used thin film forming methods such as a vacuum evaporation method, a sputtering method, a doctor blade method, a casting method, a spin coating method, and an immersion method. From the viewpoint of mass productivity and cost, a spin coating method is preferable, and from the viewpoint of obtaining a recording layer having a uniform thickness, a vacuum deposition method or the like is more preferable than a coating method. In the case of film formation by spin coating, the number of rotations is preferably from 500 to 15000 rpm. In some cases, after spin coating, treatment such as heating or exposure to solvent vapor may be performed.

When the recording layer is formed by a coating method such as a doctor blade method, a casting method, a spin coating method, and a dipping method, a coating used for dissolving the compound represented by the general formula (1) and applying the compound to a substrate. The solvent is not particularly limited as long as it does not attack the substrate. Specifically, for example, ketone alcohol solvents such as diacetone alcohol and 3-hydroxy-3-methyl-2-butanone; cellosolve solvents such as methyl cellosolve and ethyl cellosolve; chains such as n-hexane and n-octane Hydrocarbon solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, n-butylcyclohexane, tert-butylcyclohexane and cyclooctane; tetrafluoropropanol, octafluoropentanol, hexafluorobutanol and the like Perfluoroalkyl alcohol solvents; and hydroxycarboxylic acid ester solvents such as methyl lactate, ethyl lactate and methyl 2-hydroxyisobutyrate.

When the vacuum evaporation method is used, for example, the compound represented by the general formula (1) and the recording layer components such as other dyes and various additives are placed in a vacuum container, if necessary. After placing in a crucible and evacuating the inside of this vacuum vessel to about 10 ⁻² to 10 ⁻⁵ Pa with a suitable vacuum pump, the crucible is heated to evaporate the recording layer components, and the substrate is placed on the crucible. To form a recording layer.

In the recording layer, in addition to the compound represented by the general formula (1), a transition metal chelate compound (for example, acetylacetonate chelate) is used as a singlet oxygen quencher to improve stability and light resistance. , Bisphenyldithiol, salicylaldehyde oxime, bisdithio-α-diketone, etc.), or a recording sensitivity improver such as a metal compound for improving recording sensitivity. Here, the metal compound refers to a compound in which a metal such as a transition metal is contained in the compound in the form of atoms, ions, clusters, and the like. And organic metal compounds such as dihydroxyazobenzene-based complexes, dioxime-based complexes, nitrosoaminophenol-based complexes, pyridyltriazine-based complexes, acetylacetonate-based complexes, metallocene-based complexes, and porphyrin-based complexes. The metal atom is not particularly limited, but is preferably a transition metal.

In the recording layer, if necessary, a plurality of compounds represented by the general formula (1) may be used in combination.

Further, in the recording layer, in addition to the compound represented by the general formula (1), a dye of another system can be used in combination, if necessary. The dyes of the other systems are not particularly limited as long as they have appropriate absorption mainly in the oscillation wavelength range of the recording laser. Dyes suitable for recording / reproduction using a near-infrared laser having an oscillation wavelength in a wavelength band of 770 to 830 nm, used for CD-R, etc., and wavelengths of 620 to 690 nm used for DVD-R, etc. A dye or the like suitable for recording / reproduction using a red laser having an oscillation wavelength in the band is contained in the recording layer in combination with the compound represented by the general formula (1), so that a plurality of dyes belonging to different wavelength bands are included. An optical recording medium corresponding to recording / reproducing using a kind of laser beam can also be manufactured.

Other dyes other than the compound represented by the general formula (1) include metal-containing azo dyes, benzophenone dyes, phthalocyanine dyes, naphthalocyanine dyes, cyanine dyes, azo dyes, and squarylium dyes. , Metal-containing indoaniline dyes, triarylmethane dyes, merocyanine dyes, azurenium dyes, naphthoquinone dyes, anthraquinone dyes, indophenol dyes, xanthene dyes, oxazine dyes, pyrylium dyes, and the like. .

Further, a binder, a leveling agent, an antifoaming agent and the like can be used in combination as needed. Preferred binders include polyvinyl alcohol, polyvinylpyrrolidone, nitrocellulose, cellulose acetate, ketone resin, acrylic resin, polystyrene resin, urethane resin, polyvinyl butyral, polycarbonate, polyolefin and the like.

The film thickness of the recording layer is not particularly limited because a suitable film thickness varies depending on a recording method or the like, but a certain film thickness is required to enable recording. Or more, preferably 5 nm or more. However, if the thickness is too large, there is a possibility that recording cannot be performed well, and the thickness is usually 300 nm or less, preferably 200 nm or less, more preferably 100 nm or less.

反射 A reflective layer is formed on the recording layer. The thickness is preferably 50 to 300 nm.

As the material of the reflection layer, a material having a sufficiently high reflectance at the wavelength of the reproduction light, for example, a metal such as Au, Al, Ag, Cu, Ti, Cr, Ni, Pt, Ta, or Pd, alone or as an alloy Can be used. Among these, Au, Al, and Ag have high reflectivity and are suitable as the material of the reflective layer. In addition to these metals as main components, other materials may be additionally contained. Here, the main component means a component having a content of 50% or more. Materials other than the main component include, for example, Mg, Se, Hf, V, Nb, Ru, W, Mn, Re, Fe, Co, Rh, Ir, Cu, Zn, Cd, Ga, In, Si, and Ge. , Te, Pb, Po, Sn, Bi, Ta, Ti, Pt, Pd, Nd and other metals and metalloids. Among them, those containing Ag as a main component are particularly preferable because they are inexpensive, easily reflect a high reflectance, and can provide a white and beautiful ground color when a print receiving layer described later is provided. For example, an alloy containing about 0.1 to 5 atomic% of at least one selected from Au, Pd, Pt, Cu, and Nd in Ag is preferable because of high reflectance, high durability, high sensitivity, and low cost. . Specifically, for example, AgPdCu alloy, AgCuAu alloy, AgCuAuNd alloy, AgCuNd alloy, etc. As a material other than metal, a low-refractive-index thin film and a high-refractive-index thin film are alternately stacked to form a multilayer film, which can be used as a reflective layer.

方法 As a method for forming the reflective layer, for example, a sputtering method, an ion plating method, a chemical vapor deposition method, a vacuum vapor deposition method, and the like can be mentioned. In addition, a known inorganic or organic intermediate layer or adhesive layer may be provided on the substrate or under the reflective layer for the purpose of improving reflectance, recording characteristics, and adhesion.

The material of the protective layer formed on the reflective layer is not particularly limited as long as it protects the reflective layer from external force. Examples of the organic material include a thermoplastic resin, a thermosetting resin, an electron beam curable resin, and a UV curable resin. Further, examples of the inorganic substance include silicon oxide, silicon nitride, MgF ₂ , and SnO ₂ .

保護 When using a thermoplastic resin, a thermosetting resin, or the like, a protective layer can be formed by applying a coating solution prepared by dissolving in an appropriate solvent onto the reflective layer and drying. When using a UV curable resin, it is applied directly on the reflective layer, or by applying a coating solution prepared by dissolving in an appropriate solvent on the reflective layer, and curing by irradiating UV light. , A protective layer 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 of two or more. Further, the protective layer may be formed as a single layer or as a multilayer.

As a method for forming the protective layer, a coating method such as a spin coating method or a casting method, a method such as a sputtering method or a chemical vapor deposition method is used as in the recording layer, and the spin coating method is particularly preferable. The thickness of the protective layer is generally 0.1 μm or more, preferably 3 μm or more, since a certain thickness is required to fulfill the protective function. However, if the thickness is too large, the effect is not changed, and it may take a long time to form the protective layer or the cost may increase. Therefore, the thickness is usually 100 μm or less, preferably 30 μm or less.

As described above, as the layer structure of the optical recording medium, the structure in which the substrate, the recording layer, the reflective layer, and the protective layer are stacked in this order has been described as an example. However, as described above, other layer structures may be used. I do not care.

For example, another substrate may be bonded to the upper surface of the protective layer in the layer structure of the above example, or to the upper surface of the reflective layer by omitting the protective layer from the layer structure of the above example. In this case, the substrate may be a substrate without any layer, or may have an arbitrary layer such as a reflective layer on the bonding surface or the opposite surface. Similarly, two optical recording media having the layer structure of the above example and optical recording media in which the protective layer is omitted from the layer structure of the above example, with the upper surfaces of the respective protective layers and / or reflective layers facing each other. It may be attached.

Further, as an example of a preferred layer configuration of the optical recording medium of the present invention, there is a medium in which a reflective layer is provided on a substrate, and a recording layer and a protective film are further laminated on the reflective layer in this order. In this case, information is recorded / reproduced by irradiating a laser beam through the protective film (medium structure example 2).

This protective film may be formed by bonding a film or sheet-like material with an adhesive, or by applying a coating liquid for film formation using the same material as the above-described protective layer and curing or drying. You may. The thickness of the protective film is generally 0.1 μm or more, and preferably 3 μm or more, because a certain thickness is required to fulfill the protective function. However, if the thickness is too large, the effect is not changed, and it may take a long time to form the protective layer or the cost may be increased. Therefore, the thickness is usually 300 μm or less, preferably 200 μm or less.

も Even in such a layer configuration, the same layers as those in the above-described medium structure example 1 can be used for each layer such as the recording layer and the reflective layer. However, in the present layer configuration, the substrate does not need to be transparent, and therefore, a substrate made of an opaque resin, ceramic, metal (including alloy), or the like may be used in addition to the above-described materials.

に お い て Even in such a layer configuration, an arbitrary layer may be provided between each of the above-described layers as needed, as long as the characteristics of the present invention are not impaired.

By the way, as one means for increasing the recording density of the optical recording medium, there is a case where the numerical aperture of the objective lens is increased. Thereby, the light spot focused on the information recording surface can be miniaturized. However, when the numerical aperture of the objective lens is increased, when a laser beam is irradiated for recording / reproducing, the aberration of the light spot due to the warpage of the optical recording medium or the like tends to increase, so that a good recording / reproducing signal is obtained. May not be obtained stably.

収 差 These aberrations tend to increase as the thickness of the transparent substrate or the protective film through which the laser beam passes is increased. Therefore, in order to reduce the aberration, it is preferable to make the substrate and the protective film as thin as possible. However, since the substrate usually needs a certain thickness in order to secure the strength of the optical recording medium, in this case, the medium structure example 2 (the optical recording of the basic layer configuration consisting of the substrate, the reflective layer, the recording layer, and the thin protective film) Medium). Compared with the case where the substrate of the medium structure example 1 is made thinner, the protective film of the medium structure example 2 is easily made thinner. Therefore, the medium structure example 2 is preferably used.

However, even in the medium structure example 1 (optical recording medium having a basic layer structure including a transparent substrate, a recording layer, a reflective layer, and a protective layer), the thickness of the transparent substrate through which the recording / reproducing laser beam passes is 50 to 300 μm. By reducing the thickness to such an extent, the aberration can be reduced and the device can be used.

After the other layers are formed, an ultraviolet curable resin layer or an inorganic thin film is formed on the recording / reproducing laser beam incident surface (usually the lower surface of the substrate) for the purpose of protecting the surface and preventing adhesion of dust and the like. A film may be formed, and writing and printing can be performed on a surface other than the recording / reproducing laser beam incident surface (usually the upper surface of the reflective layer or the protective layer) using various printers such as an inkjet printer or a thermal transfer printer, or various writing instruments. A possible print-receiving layer may be provided.

光学 In the optical recording medium of the present invention, the shorter the wavelength of the laser light used for recording / reproducing information from the viewpoint of realizing high-density recording, the more preferable is the laser light having a wavelength of 350 to 530 nm. Representative examples of such laser light include laser light having a center wavelength of 405 nm, 410 nm, or 515 nm.

The laser light having a wavelength of 350 to 530 nm can be obtained by using a high-power semiconductor laser of 405 nm, 410 nm blue or 515 nm blue-green. In addition, for example, (a) a continuous oscillation having a fundamental oscillation wavelength of 740 to 960 nm A second harmonic generation element (SHG) converts the oscillation laser light of any of a semiconductor laser capable of oscillation and (b) a solid laser capable of continuous oscillation having a fundamental oscillation wavelength of 740 to 960 nm excited by the semiconductor laser. It is also obtained by doing.

The SHG may be any piezo element that lacks inversion symmetry, but is preferably KDP, ADP, BNN, KN, LBO, or a compound semiconductor. As a specific example of the second harmonic, in the case of a semiconductor laser having a fundamental oscillation wavelength of 860 nm, it is 430 nm which is a harmonic of the fundamental oscillation wavelength, and in the case of a solid-state laser pumped by a semiconductor laser, it is LiSrAlF doped with Cr. 430 nm of a harmonic from _six crystals (a fundamental oscillation wavelength of 860 nm).

When information is recorded on the optical recording medium of the present invention, a laser beam focused on the recording layer (usually transmitting the substrate from the substrate side) to about 0.4 to 0.6 μm is used. Is irradiated. The portion of the recording layer irradiated with the laser light undergoes thermal deformation such as decomposition, heat generation, and dissolution by absorbing the energy of the laser light, so that the optical characteristics change.

(4) When reproducing recorded information, the recording layer is also irradiated with a laser beam having lower energy (usually from the same direction as the recording). In the recording layer, information is reproduced by reading the difference between the reflectance of a portion where the optical characteristic has changed (that is, the portion where information is recorded) and the reflectance of a portion where no change has occurred. It is.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist.
[Method of synthesizing compound]
The method for synthesizing the compound represented by the general formula (1) is not particularly limited, but examples of the general production method include the following.

For example, in the case of synthesizing a compound in which l or m = 1 and l + m = 1, k = 0, n = 0, and rings A and B are represented by a benzene ring in the general formula (1), for example, benzenesulfonamide and By heating benzaldehyde in toluene under BF ₃ catalyst

can get.

Here, by using cinnamaldehyde instead of benzaldehyde, a compound in which k or n = 1 in the general formula (1) is obtained. Similarly, by using different aldehydes, various compounds having different k and n can be synthesized.

Further, by using sulfamide as a raw material as described in Tetrahedron Letters, 37, 16, 2859-2862 (1996) instead of benzenesulfonamide, a compound having l = 1, m = 1 and l + m = 2 can be obtained. Can be obtained.

Furthermore, by using various benzene ring derivatives, heteroaromatic rings and the like, compounds having rings A and B having various ring structures as shown in the exemplified compounds can be synthesized.

[Example 1] (a) Example of producing dye compound

1.57 g (10 mmol) of benzenesulfonamide represented by the structural formula [I] and 1.95 g (11 mmol) of p-diethylaminobenzaldehyde represented by the structural formula [II] are added to 35 ml of toluene, and the mixture is stirred at 70 ° C. It was dissolved by heating. Thereafter, 0.6 g of boron trifluoride diethyl ether complex was added dropwise, and the mixture was refluxed for 3 hours. The reaction solution was cooled, unreacted benzenesulfonamide was removed by filtration, 100 ml of water was added to the filtrate for extraction and washing, and anhydrous magnesium sulfate was added, and the mixture was allowed to stand overnight. Thereafter, this solution was filtered, and the filtrate was distilled off. Then, 30 ml of diisopropyl ether was added, and the mixture was stirred, filtered, and the solid was separated by filtration to obtain 0.84 g of a solid represented by the structure of Exemplified Compound (1a). Was completed (yield 26.5%).

FIG. 1 shows the measurement results of the absorption spectrum of the product in chloroform.

The maximum absorption wavelength (λmax) of the exemplified compound (1a) in chloroform was 392.5 nm, and the molar extinction coefficient was 5.5 × 10 ⁴ .
(B) Production Example of Recording Medium Exemplified compound (1a) was dissolved in octafluoropentanol and adjusted to 1.0 wt%. A solution obtained by filtering the solution was dropped on an injection-molded polycarbonate resin substrate having a diameter of 120 mm and a thickness of 1.2 mm, applied by a spinner method, and then dried at 100 ° C. for 30 minutes.

FIG. 2 shows the measurement results of the absorption spectrum of the coating film. The maximum absorption wavelength (λmax) of the coating film of the exemplary compound (1a) was 391 nm.

In the present invention, the absorption spectrum of the coating film is measured by irradiating the coating film with light incident from the coating film side and using an ultraviolet-visible spectrophotometer with air as a reference.

On this coating film, for example, Ag or the like is formed by a sputtering method or the like to form a reflective layer, and then an ultraviolet curable resin is applied by a spin coating method or the like, and then cured by irradiating with ultraviolet light to be protected. An optical recording medium can be obtained by forming a layer. From the value of the maximum absorption wavelength (λmax) of the coating film, it is apparent that this optical recording medium can be recorded and reproduced by a semiconductor laser having a center wavelength of 405 nm, for example.

[Example 2] (a) Example of producing dye compound

1.71 g (10 mmol) of p-toluenesulfonamide represented by the above structural formula [III]
And 1.62 g (10 mmol) of 4-methoxycinnamaldehyde represented by the above structural formula [IV] were added to 40 ml of toluene, and dissolved by heating at 70 ° C. with stirring. Thereafter, 0.6 g of boron trifluoride diethyl ether complex was added dropwise, and the mixture was refluxed for 7 hours. The reaction solution was cooled, unreacted p-toluenesulfonamide was removed by filtration, 75 ml of water was added to the filtrate for extraction and washing, and anhydrous magnesium sulfate was added and the mixture was allowed to stand overnight. Thereafter, this solution was filtered, and the filtrate was distilled off. Then, 20 ml of diisopropyl ether was added, stirred, filtered, and the solid was separated by filtration to obtain 0.81 g of a solid represented by the structure of Exemplified Compound (2a). (Yield 26.6%).

The maximum absorption wavelength (λmax) of the product in chloroform was 353.5 nm, and the molar extinction coefficient was 2.5 × 10 ⁴ .
(B) Production Example of Recording Medium Exemplified compound (2a) was dissolved in octafluoropentanol and adjusted to 1.0 wt%. A solution obtained by filtering the solution was dropped on an injection-molded polycarbonate resin substrate having a diameter of 120 mm and a thickness of 1.2 mm, applied by a spinner method, and then dried at 100 ° C. for 30 minutes. The maximum absorption wavelength (λmax) of this coating film was 357.5 nm.

On this coating film, for example, Ag or the like is formed by a sputtering method or the like to form a reflective layer, and then an ultraviolet curable resin is applied by a spin coating method or the like, and then cured by irradiating with ultraviolet light to be protected. An optical recording medium can be obtained by forming a layer. From the value of the maximum absorption wavelength (λmax) of the coating film, it is apparent that this optical recording medium can be recorded and reproduced by a semiconductor laser having a center wavelength of 405 nm, for example.

[Examples 3 to 9]
Hereinafter, each of the exemplified compounds (3a) to (52) was synthesized using the above synthesis method and other methods, and then a coating film was formed in the same manner as in Example 1.

Table 1 shows the maximum absorption wavelength (λmax), the molar extinction coefficient, and the maximum absorption wavelength (λmax) of the coating film in the solution together with the results of Examples 1 and 2.

On these coating films, for example, Ag or the like is formed by a sputtering method or the like to form a reflective layer, and then an ultraviolet curable resin is applied by a spin coating method or the like, and then irradiated with ultraviolet light to be cured. An optical recording medium can be obtained by forming a protective layer. From the value of the maximum absorption wavelength (λmax) of the coating film, it is clear that these optical recording media can be recorded and reproduced by, for example, a semiconductor laser having a center wavelength of 405 nm.

[Example 10]
(A) Production Example of Organic Dye Using the above synthesis method and other methods, p-toluenesulfonamide and N-ethyl-N-
Exemplary compound (53) was synthesized from (2-cyanoethyl) benzaldehyde. The maximum absorption wavelength (λmax) of the product in chloroform was 373.5 nm, and the molar extinction coefficient was 4.7 × 1.
0 was ^4.
(B) Production Example of Recording Medium Exemplified compound (53) was dissolved in octafluoropentanol and adjusted to 1.0 wt%. A solution obtained by filtering the solution was dropped on an injection-molded polycarbonate resin substrate having a diameter of 120 mm and a thickness of 1.2 mm, applied by a spinner method, and then dried at 100 ° C. for 30 minutes. The maximum absorption wavelength (λmax) of this coating film was 380.5 nm. Table 1 shows the results.
(C) Production Example of Optical Recording Medium Using a Ni stamper, polycarbonate was injection molded to form a groove having a groove pitch of 425 nm, a groove width of 200 nm, and a groove depth of about 90 nm, a diameter of 120 mm and a thickness of 0.6 mm. Was manufactured. Next, a 0.4% octafluoropentanol solution of the exemplary compound (53) is applied on the first substrate by a spin coating method, and is heated at 100 ° C. for 30 minutes to obtain a dye recording layer having a thickness of about 60 nm. Was formed. Next, an Ag alloy containing 97 atomic% or more of Ag was sputtered to form a reflective layer having a thickness of about 100 nm.

Next, an adhesive made of an ultraviolet curable resin is applied on the reflective layer, and a second substrate made of polycarbonate having a diameter of 120 mm and a thickness of 0.6 mm prepared in advance is placed thereon. The substrate was irradiated with ultraviolet light from the substrate side to cure the adhesive, thereby producing an optical recording medium.

Light was incident on the recording layer from the first substrate side to record and reproduce information. For recording and reproduction, an optical system having a wavelength of 405 nm and an NA of 0.65 was used. The recording conditions were such that a mark of 8T = 690 nm was recorded at a linear velocity of 5.7 m / s and a recording power of 11 mW. After that,
Data was read while irradiating with a laser beam having a reproduction intensity of 0.2 mW. At this time, C / N, which is a measure of the ratio of noise to signal strength, was measured and found to be 34 dB. From this result, it can be seen that the dye (53) can be used for an optical recording medium using a short wavelength. The C / N can be further improved by further optimizing various conditions such as a recording strategy and a dye film thickness.

Therefore, if information is recorded on the optical recording medium using a short-wavelength laser beam having a wavelength of 350 nm to 530 nm, higher-density and larger-capacity information can be recorded and reproduced.

3 is an absorption spectrum of a compound synthesized in Example 1 in a chloroform solution. 3 is an absorption spectrum of a coating film of the compound synthesized in Example 1.

Claims (5)

An optical recording medium provided with a recording layer capable of recording or reproducing information by a laser on a substrate, wherein the recording layer contains a compound represented by the following general formula (1).

(Wherein, R ₁ to R ₆ each independently represent a hydrogen atom, a linear or branched alkyl group which may be substituted. K and n each independently represent an integer of 0 to 2, and 0 ≦ k + n ≤ 4. l and m each independently represent 0 or 1, and 1 ≤ l + m ≤ 2. Ring A and ring B each independently represent an aromatic group optionally having any substituent Represents a ring, provided that the arbitrary substituents may be bonded to each other to form a ring.) The optical recording medium according to claim 1, wherein in the general formula (1), R ₁ to R ₆ represent a hydrogen atom or an unsubstituted linear alkyl group having 1 to 3 carbon atoms. The optical recording medium according to claim 1, wherein, in the general formula (1), k and n each independently represent 0 or 1, and 0 ≦ k + n ≦ 2. In the general formula (1), ring A and ring B each independently represent a 5- to 6-membered monocyclic ring or a 2- to 3-condensed ring which may have an arbitrary substituent (however, The optical recording medium according to any one of claims 1 to 3, wherein arbitrary substituents may be bonded to each other to form a ring). 5. An optical recording method comprising recording information on the optical recording medium according to claim 1, using a laser beam having a wavelength of 350 nm to 530 nm.

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