Patent Application
20080008850
These and other features of this invention will now be described with reference to the drawings of preferred embodiments which are intended to illustrate and not to limit the invention. The drawings are oversimplified for illustrative purposes and are not to scale.
In at least one embodiment of the present invention, a thin film containing an H-aggregate is formed using a mono(aza)methine dye composition prepared by adding a basic compound to a mono(aza)methine compound represented by the above general formula [1] or [2]. Accordingly, optical information recording media (an HD DVD-R disc 1 and a Blu-ray Disc-R disc 20) each having a uniform optical recording layer with a high refractive index can be realized using a solution or a dispersion liquid containing the dye composition by a simple spin-coating method.
In the mono(aza)methine compound (mono(aza)methine cyanine dye) represented by the above general formula [1] or [2], when A in the molecular (dye) skeleton is CH, the compound is a monomethine cyanine dye, and when A in the molecular (dye) skeleton is N, the compound is a mono(aza)methine cyanine dye. For example, when at least one of Y1 and Y2 is O, the compound includes an oxazole nucleus. When at least one of Y1 and Y2 is S, the compound includes a thiazole nucleus. When at least one of Y1 and Y2 is N, the compound includes an imidazole nucleus. When at least one of Y1 and Y2 is CH═CH, the compound includes a pyridine nucleus. Y1 and Y2 may be the same or different. Accordingly, the compound has a structure in which these nuclei are bonded by a monomethine chain or a monoazomethine chain (—N═) and is referred to as a mono(aza)methine cyanine compound (mono(aza)methine cyanine dye).
In the above general formulae [1] and [2], 1/m Xm represents at least one type selected from the group consisting of an organic ion, an inorganic ion, and an organometallic ion. When Xm has m negative charges (m−), Xm represents at least one type selected from the group consisting of an organic anion, an inorganic anion, and an organometallic anion, wherein m represents an integer of 1 to 4. When m is 1, the anion has a single negative charge. When m is 2 to 4, the anion has m negative charges. In such a case, the number of charges of the anion may be multiplied by 1/m so as to correspond to a single negative charge. Specific examples of the organic anion include anions of alkyl carboxylic acids, such as CH3COO−, trifluoromethyl carboxylic acid (CF3COO−), alkylsulfonic acid, such as CH3SO3−, benzenesulfonic acid (φ-SO3−, wherein φ represents a benzene ring, hereafter the same), toluenesulfonic acid (H3C-φ-SO3−), and benzenecarboxylic acid (φ-COO−). Specific examples of the inorganic anion (negative ion) include halogen atom ions (Cl−, Br−, and I−); PF6−; SbF6−; anions of phosphoric acid, perchloric acid (ClO4−), periodic acid, and fluoroboric acid (BF4−); NO3−; OH−; SCN−; and anions of tetraphenylboric acid and tungstic acid. When Xm has m positive charges (m+), Xm represents at least one type selected from the group consisting of an organic cation, an inorganic cation, and an organometallic cation. An example of them includes a quaternary amine. Specific examples thereof include ammonium, monoalkylammonium to tetraalkylammonium, and monoalkylammonium to tetraalkylammonium in which a phenyl group has substituted for entire or a part of alkyl groups. When one of R1 and R2 represents (CH2)nSO3− or (CH2)nCOO− (wherein n represents an integer selected from 0 to 5), 1/m Xm may not be contained.
In the above general formula [1], Z1 and Z2 each represent an atomic group required for forming a five- or six-membered aromatic ring or a five- or six-membered nitrogen-containing heterocyclic ring (i.e., forming any one of cyclic groups selected from a five-membered aromatic ring, a six-membered aromatic ring, a five-membered nitrogen-containing heterocyclic ring, and a six-membered nitrogen-containing heterocyclic ring). Z1 and Z2 may be the same or different. Z1 or Z2 may have a substituent.
Examples of the above aromatic rings include a substituted or unsubstituted benzene ring or a substituted or unsubstituted naphthalene ring. Z1 represents any one of four atomic groups represented by the following general formula [3]. Z2 represents any one of four atomic groups represented by the following general formula [4]. Z1 and Z2 may be the same or different (wherein D1 and D2 each represent a substituent selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, a halogen atom, a carboxyl group, an alkoxycarbonyl group, an alkylcarboxyl group, an alkylhydroxyl group, an aralkyl group, an alkenyl group, an alkylamido group, an alkylamino group, an alkylsulfoneamido group, an alkylcarbamoyl group, an alkylsulfamoyl group, an alkylsulfonyl group, a phenyl group, a cyano group, an ester group, a nitro group, an acyl group, an allyl group, an aryl group, an aryloxy group, an alkylthio group, an arylthio group, a phenylazo group, a pyridinoazo group, an alkylcarbonylamino group, a sulfonamide group, an amino group, an alkylsulfone group, a thiocyano group, a mercapto group, a chlorosulfone group, an alkylazomethine group, an alkylaminosulfone group, a vinyl group, and a sulfone group. D1 and D2 may be the same or different, and p and q each represent the number of substituents and each represent an integer of 1 or more).
In the above general formula [2], each of R3, R4, R5, and R6 is selected from the group consisting of a hydrogen atom, a halogen atom, an alkoxy group, a cyano group, a halogenated alkyl group, a phenyl group having a substituent, and an alkyl group of (CH2)nCH3 (wherein n represents an integer selected from 0 to 5). Furthermore, each of R3, R4, R5, and R6 may be selected from the group consisting of other aromatic rings and heterocyclic rings. The selected one may have a substituent. R3, R4, R5, and R6 may be the same or different. However, at least one of R3 to R6 may be a Cl group. Also, the benzene rings disposed at both sides of the mono(aza)methine chain may have Cl groups symmetrically.
More specifically, in the above general formula [2], at least one of R3 to R6 may be substituted with a substituent. Examples of the substituent include aliphatic hydrocarbon groups, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, and a tert-pentyl group; halogenated aliphatic hydrocarbon groups, such as halogenated alkyl groups; ether groups, such as a methoxy group, a trifluoromethoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a tert-butoxy group, a pentyloxy group, a phenoxy group, and a benzyloxy group; ester groups, such as a methoxycarbonyl group, a trifluoromethoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an acetoxy group, a trifluoroacetoxy group, and a benzyloxy group; alkylsulfonyl groups, such as a methylsulfonyl group, an ethylsulfonyl group, a propylsulfonyl group, an isopropylsulfonyl group, a butylsulfonyl group, a tert-butylsulfonyl group, and a pentylsulfonyl group; alkylsulfamoyl groups, such as a methylsulfamoyl group, a dimethylsulfamoyl group, an ethylsulfamoyl group, a diethylsulfamoyl group, a propylsulfamoyl group, a dipropylsulfamoyl group, a butylsulfamoyl group, a dibutylsulfamoyl group, a pentylsulfamoyl group, and a dipentylsulfamoyl group; halogen groups, such as a fluoro group, a chloro group, a bromo group, and an iodo group; a nitro group; and a cyano group. Each of R3 to R6 may have at least one substituent. All of or a part of R3 to R6 may be the same or different. It is desirable that each of the aromatic rings is a monocyclic benzene ring (may also be a phenyl group which may have a substituent), and each of the heterocyclic rings has at least one heteroatom selected from a nitrogen atom, an oxygen atom, a sulfur atom, a selenium atom, and a tellurium atom. The aromatic rings and the heterocyclic rings may be the same or different between (R3, R4) and (R5, R6), and each of the rings may have at least one substituent.
These aromatic rings and the heterocyclic rings may have at least one substituent. Examples thereof include aliphatic hydrocarbon groups, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a 1-methylpentyl group, a 2-methylpentyl group, a hexyl group, an isohexyl group, and a 5-methylhexyl group; alicyclic hydrocarbon groups, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cyclohexenyl group; aromatic hydrocarbon groups, such as a phenyl group, a biphenylyl group, an o-tolyl group, a m-tolyl group, a p-tolyl group, an o-cumenyl group, m-cumenyl group, p-cumenyl group, a xylyl group, a mesityl group, a styryl group, a cinnamoyl group, and a naphthyl group; ester groups, such as a methoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, an acetoxy group, and a benzoyloxy group; substituted or unsubstituted aliphatic, alicyclic, or aromatic amino groups, such as a primary amino group, a methylamino group, a dimethylamino group, an ethylamino group, a diethylamino group, a propylamino group, a dipropylamino group, an isopropylamino group, a diisopropylamino group, a butylamino group, and a dibutylamino group; alkylsulfamoyl groups, such as a methylsulfamoyl group, a dimethylsulfamoyl group, an ethylsulfamoyl group, a diethylsulfamoyl group, a propylsulfamoyl group, a dipropylsulfamoyl group, an isopropylsulfamoyl group, a diisopropylsulfamoyl group, a butylsulfamoyl group, and a dibutylsulfamoyl group; a carbamoyl group; a carboxyl group; a cyano group; a nitro group; a hydroxyl group; a sulfo group; a sulfoamino group; and a sulfonamide group.
In the mono(aza)methine compounds (mono(aza)methine cyanine dyes) represented by the above general formula [1] or [2], when cis/trans structural isomers are present, both isomers are included in at least one embodiment of the present invention.
More specifically, in addition to compounds described in examples described below, monomethine cyanine compounds represented by the following formulae [5] to [8] are also included in at least one embodiment of the present invention.
A mono(aza)methine compound represented by the above general formula [1] or [2], or any of the specific compounds that are described above or below and that belong to general formula [1] or [2], a basic compound, and a solvent are selected. A dye composition containing the former two components or a dye composition containing these three components is prepared in the form of a solution or a dispersion liquid, and a thin film containing an H-aggregate of the mono(aza)methine compound can be easily formed by a spin-coating method.
Examples of the basic compound to be added include hydroxides of quaternary amines, more specifically, ammonium hydroxide, tetraalkylammonium hydroxide (the alkyl group includes lower alkyl groups, such as a methyl group, and a plurality of alkyl groups may be the same or different), and compounds to be used in the examples described below, although not limited to them.
The molar ratio of OH− (one hydroxide ion) in the basic compound to one molecule of the mono(aza)methine compound represented by the above general formula [1] or [2], or any of the specific compounds that are described above or below and that belong to general formula [1] or [2] is preferably in the range of 0.2 to 3, and more preferably, in the range of 1 to 3.
A fluorinated alcohol, such as 2,2,3,3-tetrafluoro-1-propanol, is preferably used as the solvent. However, other solvents, such as chloroform, dichloroethane, methyl ethyl ketone, dimethylformamide, methanol, toluene, cyclohexanone, acetylacetone, diacetone alcohol, cellosolves, e.g., methyl cellosolve, and dioxane, may be used alone or in combinations to the extent that a substrate is not corroded. At least one of these solvents may be used in combination with a fluorinated alcohol.
By using such a dye material that forms an H-aggregate, the refractive index of the optical recording layer 3 can be increased, the thickness of the optical recording layer 3 can be easily decreased, a high degree of modulation can be ensured, and optical information recording media 1 and 20 having excellent recording properties over a wavelength range of about 350 to 500 nm can be produced. More specifically, by breaking the H-aggregate during recording, the difference in the refractive index before and after recording is ensured, and the recording sensitivity can be improved.
Thermal decomposition of general dyes is conducted by an exothermic reaction, whereas thermal decomposition in the H-aggregate state of the mono(aza)methine compound used in at least one embodiment of the present invention is conducted by an endothermic reaction. Therefore, heat dissipation during decomposition can be suppressed.
In the present disclosure where conditions and/or structures are not specified, the skilled artisan in the art can readily provide such conditions and/or structures, in view of the present disclosure, as a matter of routine experimentation.
Also, in the present disclosure, the numerical numbers applied in embodiments can be modified by 50% in other embodiments, and the ranges applied in embodiments may include or exclude the endpoints.
Dye materials for an optical information recording medium, optical information recording media including the dye materials, and methods of producing the optical information recording medium according to examples of the present invention will now be described with reference to the drawings. The same parts as those in
First, 2.0 g (3.8 mmol because the molecular weight is 531.81) of monomethine cyanine compound (Compound I) represented by formula [9] below was fed into a 100-mL volumetric flask. A 10-% methanol solution of tetramethylammonium hydroxide (9.1 mol/L) was then added in an amount of 0 times (without addition), 1 times (0.42 mL) (more specifically, the molar ratio of OH− to Compound I was 1 (1 molecule of Compound I: OH− 1 mol, and this also applies to the following cases)), or 2 times (0.83 mL) the amount of Compound I. Furthermore, 2,2,3,3-tetrafluoro-1-propanol (TFP) was added to each flask so that the total volume reached 100 mL, and the mixture was sufficiently stirred to dissolve the compound. Thus, monomethine dye compositions each containing Compound I in a concentration of 20 g/L were prepared.
Subsequently, 5 mL of each solution of the monomethine dye composition prepared as described above was dripped to a 1,000-mL volumetric flask, and 2,2,3,3-tetrafluoro-1-propanol was added to the flask so that the total volume reached 1,000 mL. The mixture was sufficiently stirred, and the spectrum of the resulting solution was then measured.
Subsequently, 1 mL of each solution of the above monomethine dye composition was dripped to a glass single plate 4 centimeters square with a thickness of 0.6 mm. Spin coating was then conducted at a rotational speed of 1,500 rpm for 30 seconds, thereby, preparing a uniform H-aggregate thin film. The spectrum of the thin film of each monomethine dye composition was measured.
For comparison, a monomethine cyanine dye (Compound X) represented by formula [10] below was used (2.0 g corresponds to 3.2 mmol because the molecular weight is 629.49) as a cyanine dye compound. As in the above-described case of Compound I, a 10-% methanol solution of tetramethylammonium hydroxide was added in an amount of 0 times (without addition), 1 times (0.35 mL), or 2 times (0.70 mL) the amount of Compound X. Solutions of monomethine dye composition each containing Compound X in a concentration of 20 g/L were prepared. The above-described single plate was spin-coated with each of these solutions. The spectrum of each thin coating film was measured.
In contrast, regarding the absorption spectra of Compound X on the single plate shown in
As described above, the formation of an H-aggregate of a dye film can be checked by observing a change in the absorption spectra of a compound in a solution state and in a thin film state.
For example, the formation of the H-aggregate can be checked by the shift of the absorption peak in the thin film state to the short-wavelength side as compared with the absorption peak in the solution state.
However, the method is not limited thereto and various methods can be employed. For example, the formation of the H-aggregate can also be checked by comparing an absorption spectrum of a monomer in a solution with an absorption spectrum in the thin film state by the method described above.
As described above, in the cyanine dye thin films of Compound I (without addition of tetramethylammonium hydroxide) and Compound X, no H-aggregate was formed. Regarding the monomethine compound of Compound I, in particular, when tetramethylammonium hydroxide was added in an amount 2 times the amount of the compound, an H-aggregate was formed. By applying this composition by spin coating, a uniform H-aggregate thin film was able to be formed more easily.
Monomethine cyanine dyes (Compounds II, III, and IV) represented by formulae [11], [12], and [13], respectively, were used instead of Compound I in Example 1. As in above-described case of Compound I, tetramethylammonium hydroxide was added in an amount of 0 times (without addition) and 1 times the amount of the compound to prepare solutions. Each of these solutions was applied on the above-described single plate by spin coating. The spectrum of each thin film of Compound II, III, or IV formed on the single plate was measured. The results thereof are shown in
Regarding the absorption spectra of thin films on the single plates as shown in
Table 1 (see Example 7 described later) below shows optical properties of thin films (each formed on a single plate) of Compound II (with addition of tetramethylammonium hydroxide in an amount 1 times the amount of compound) and Compound X at a wavelength of 405 nm. The refractive index n of Compound II (with addition of tetramethylammonium hydroxide in an amount 1 times the amount of the compound) was improved by forming an H-aggregate, and thus, satisfactory optical properties were obtained.
Each of thin films of monomethine dye compositions was formed (on single plates) as in example 1 except that monomethine cyanine compound (Compound V) represented by formula [14] below was used instead of Compound I and a basic compound (base) represented by formula [15] below was added in an amount of zero (without addition) or 1 times the amount of the compound instead of tetramethylammonium hydroxide in example 1. The spectrum of each thin film was measured. The results thereof are shown in
As is clear from
Each of thin films of mono(aza)methine dye compositions was formed (on single plates) as in Example 1 except that mono(aza)methine cyanine compound (Compound VI) represented by formula [16] was used instead of Compound I and a basic compound (base) represented by formula [17] was added in an amount of zero (without addition) or 1 times the amount of the compound instead of tetramethylammonium hydroxide in Example 1. The spectrum of each thin film was measured. The results thereof are shown in
As is clear from
A description will be made of an example in which a thin film of the monomethine dye composition (H-aggregation monomethine dye thin film) prepared by adding tetramethylammonium hydroxide and a solvent to Compound I used in Example 1 was applied to an optical recording layer 3 of an HD DVD-R disc 1.
First, 2.0 g of monomethine cyanine compound (Compound I) represented by the above formula [9] was dissolved into 100 mL of 2,2,3,3-tetrafluoro-1-propanol. Furthermore, 0.83 mL of 10-% methanol solution of tetramethylammonium hydroxide was added to the solution (in an amount of 2 times the amount of Compound I (the molar ratio of OH− to 1 mole of Compound I being 2)), thus preparing a solution of Compound I having a concentration of 20 g/L. Compound VII represented by formula [18] below serving as a light stabilizer was added to the solution in an amount of 30 percent by weight. Other stabilizers of aminium base and diimonium base may also be used.
Subsequently, 1 mL of the resulting solution was applied on a disc-shaped polycarbonate substrate 2 having an outer diameter of 120 mm, a thickness of 0.6 mm, and a pregroove 7 with a pitch of 0.40 μm by a spin-coating method at a predetermined rotational speed, so that a uniform H-aggregate thin film was prepared.
The transparent substrate 2 coated with the dye was heat-treated at 80° C. for 30 minutes to volatilize the residual excess solvent and moisture, thus forming a dye surface (optical recording layer 3).
Furthermore, a light-reflecting layer 4 having a thickness of 100 nm was formed on the optical recording layer 3 by sputtering silver (Ag).
The dye spattered on the peripheral edge of the substrate 2 was removed by washing with methanol.
Furthermore, a UV curable resin adhesive SD-318 (manufactured by Dainippon Ink and Chemicals, Incorporated) was applied on the light-reflecting layer 4 by spin coating. The adhesive was then cured by irradiation of ultraviolet rays to form a protective layer 5.
A UV curable resin adhesive was applied on the surface of the protective layer 5, and a dummy substrate 6 whose material and shape (thickness: 0.6 mm, outer diameter: 120 mm) were the same as those of the substrate 2 was bonded thereto. The adhesive was then cured by irradiation of ultraviolet rays, thereby bonding the dummy substrate 6. Thus, the HD DVD-R (write-once HD DVD) disc 1 was prepared.
As described above, the HD DVD-R disc 1 having the optical recording layer 3 composed of a uniform thin film containing an H-aggregate of a monomethine cyanine compound was obtained using the monomethine dye composition containing Compound I and tetramethylammonium hydroxide.
In addition, an optical recording layer 3 was formed as in the above Example to prepare an HD DVD-R disc 1 except that Compound X used in Comparative example 1 was used instead of Compound I.
Table 1, as described above, also shows evaluation results of electrical properties of the HD DVD-R disc 1 (Example), which was an HD DVD-R disc prepared as in Example 7 except that Compound II was used instead of Compound I, and an HD DVD-R disc 1 (Comparative example) prepared by using Compound X. The power required for recording onto the HD DVD-R disc 1 having the optical recording layer 3 made of the monomethine dye composition containing Compound II and tetramethylammonium hydroxide was lower than that onto the HD DVD-R disc 1 prepared using Compound X. Therefore, regarding the HD DVD-R disc 1 prepared using Compound II, the recording sensitivity was more satisfactory, the C/N level in the shortest mark length was able to be improved, and symmetry during recording of random recording signals was able to be achieved with a low power.
An HD DVD-R (write-once HD DVD) disc 1 having an optical recording layer 3 composed of a uniform thin film containing an H-aggregate of a monoazamethine cyanine compound dye was prepared as in Example 7 except that, instead of 2.0 g of Compound I, Compound VI used in Example 6 was used in such a way that the number of moles of Compound VI was the same as that of Compound I in Example 7 and the base represented by the above formula [17] was used in an amount 1 times the amount of the compound.
Evaluation results similar to those of the HD DVD-R disc 1 prepared using Compound II, as shown in Table 1, were obtained. The power required for recording onto the HD DVD-R disc 1 having the optical recording layer 3 made of the monoazamethine dye composition containing Compound VI and the base represented by the above formula [17] was lower than that onto the HD DVD-R disc 1 prepared using Compound X. Therefore, regarding the HD DVD-R disc 1 prepared using Compound VI, the recording sensitivity was more satisfactory, the C/N level in the shortest mark length was able to be improved, and symmetry during recording of random recording signals was able to be achieved with a low power.
When Blu-ray Disc-R (write-once Blu-ray) discs 20 were prepared as in Examples 7 and 8 using each of Compounds I and VI and each of tetramethylammonium hydroxide and the compound represented by the above formula [17], evaluation results similar to those of the HD DVD-R (write-once HD DVD-R) disc 1 in Examples 7 and 8 were obtained. The same goes for the above-described other dyes.
The present application claims priority to Japanese Patent Application No. 2006-189081, filed Jul. 10, 2006, the disclosure of which is incorporated herein by reference in its entirety.
It will be understood by those of skill in the art that numerous and various modifications can be made without departing from the spirit of the present invention. Therefore, it should be clearly understood that the forms of the present invention are illustrative only and are not intended to limit the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-189081 | Jul 2006 | JP | national |
