JPH11170695A - Optical recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve light stability, preservative stability, and dissolvability to a solvent by the use of a specific compound for cyanin coloring matter as an optical recording material employed in its recording layer in an optical recording medium that implements recording by giving information as a thermal information pattern by laser or the like. SOLUTION: Cyanin coloring matter is prepared from a substance indicated by formula I, which corresponds to writing performed by a red color semiconductor laser of 620-690 nm being most suitable to an optical recording medium (DVD-R) that accords with a DVD standard, and is capable of performing a postscript or recording. In the formula, A is a halogen atom or nitro group, B is a substituent group represented by formulas II-V, C is a chain and/or annular hydrocarbon group or a substituent group represented by formula VI. X is -C(CH3 )3 -,-O-,-S-, or the like, Y is an alkylene group, Z is an alkyl group, (n) is an integer of 1 or 2, and An<-> is an anion. R2 -R4 are each an alkyl group or a group of -Y-O-Z, (m) is an integer of 0-4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording material used for an optical recording medium for recording by giving information as a thermal information pattern using a laser or the like. The present invention relates to an optical recording material used for an optical recording medium having a high density and capable of high-density optical recording and reproduction with a low energy laser or the like.

[0002]

2. Description of the Related Art Generally, an optical recording medium has a feature that the recording medium does not wear and deteriorate because the recording and reading heads do not come into contact with the medium. Optical recording media added as information have the advantage of not requiring a development process in a dark room, and are being actively developed.

[0003] Such an optical recording medium uses recording light as heat. For example, by forming optically detectable pits in a thin recording layer provided on a base, information can be recorded at a high density. Can be recorded.

The writing of information on a recording medium is performed by scanning a laser focused on the surface of the recording layer and forming pits in the recording layer that has absorbed the irradiated laser energy. In the information recorded on the recording medium, the formed pits can be detected by reading light.

As a recording layer of such an optical recording medium, an inorganic substance such as a metal thin film such as an aluminum vapor-deposited film, a tellurium oxide thin film, a bismuth thin film, or a chalcogenide-based amorphous glass film has been mainly used. .

[0006] It is difficult to form these thin films by a coating method, and it is necessary to form them by sputtering or vacuum deposition. However, this method has a drawback that the operation is complicated. In addition, when the above-mentioned inorganic substance is used, there are drawbacks such as high reflectance with respect to laser light, high thermal conductivity, and low utilization of laser light.

For this reason, there has been proposed a method of using, as a recording layer, an organic compound mainly composed of a dye as an optical recording material, which can form pits by a semiconductor laser, instead of an inorganic substance.

As these dyes, for example, cyanine dyes such as indolenine type, thiazole type, imidazole type, oxazole type, quinoline type and selenazole type are known. These dyes are salts of a cyanine dye cation with various anions such as a halogen anion and a perchlorate anion. In particular, indolenine dyes are preferably used because of their high sensitivity.

Optical recording media using such dyes include:
Wavelength 770 corresponding to compact disk (CD) standard
An optical recording medium (CD-R) that can be written and reproduced by a near-infrared semiconductor laser of up to 830 nm has been put to practical use.

[0010] Recently, 62 wavelengths shorter than 770 nm have been used.
A red semiconductor laser with a wavelength of 0 to 690 nm was developed. The recording density was increased by making the beam spot smaller, and a large-capacity optical recording medium (digital versatility) capable of storing moving images using data compression technology. Discs and DVDs) have also been put to practical use.

The present invention relates to a cyanine dye suitable for an optical recording medium (DVD-R) that can be additionally recorded or recorded and conforms to the DVD standard.

As a dye corresponding to writing with a red semiconductor laser of 620 to 690 nm, for example, an optical recording medium using an indocarbocyanine dye in a recording layer has been proposed in, for example, JP-A-59-55795. I have.

However, these dyes inherently have high crystallinity, and when used as a thin film such as a DVD-R, the dye crystallizes gradually with the passage of time, resulting in a decrease in sensitivity and reflectance. Had disadvantages.

Until now, in order to prevent crystallization of the dye, countermeasures have been taken such as introducing a sterically bulky substituent into the dye molecule to make it amorphous. However, the substituents that can be introduced are limited in terms of synthesis, and the introduction of special substituents makes synthesis difficult, and there is a problem of lack of versatility.

[0015] Accordingly, an object of the present invention is to provide an optical recording material having good light stability, storage stability and solubility in a solvent, which is useful as an optical recording material used in a recording layer of an optical recording medium. Low cyanine dyes.

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the above object can be achieved by using a specific asymmetric indolenine cyanine dye alone or in combination with another dye. Was found.

The present invention has been made based on the above findings, and comprises an optical compound comprising a compound represented by the following general formula (I) (the same as the above [Chemical formula 1]). It provides a recording material.

[0017]

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[0018]

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[0019]

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[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the optical recording material of the present invention will be described in detail.

The compound represented by the above general formula (I), which is the optical recording material of the present invention, is a dye used in a recording layer of an optical recording medium. In the compound represented by the general formula (I), examples of the halogen atom represented by A include fluorine, chlorine, bromine, and iodine. R ₁ , R ₂ , R ₃ , R ₄
And the alkyl group having 1 to 8 carbon atoms represented by Z includes methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, isobutyl, amyl, isoamyl, tert-amyl, hexyl, heptyl, Octyl, isooctyl, tertiary octyl, 2-ethylhexyl and the like can be mentioned. Examples of the linear and / or cyclic hydrocarbon group having 1 to 12 carbon atoms represented by C include, for example, methyl, ethyl, propyl, isopropyl , Butyl, sec-butyl, tert-butyl, isobutyl, amyl, isoamyl,
Tertiary amyl, hexyl, heptyl, octyl, isooctyl, tertiary octyl, 2-ethylhexyl, cyclohexylmethyl, cyclohexylethyl, cyclohexylpropyl, 4-methylcyclohexylmethyl, 4-ethylcyclohexylmethyl, heptahydronaphthylmethyl,
Heptahydronaphthylethyl and the like, and as the alkylene group having 1 to 4 carbon atoms represented by Y, for example,
Examples thereof include linear or branched alkylene groups such as methylene, ethylene, propylene, and butylene. In particular, a compound in which A is a nitro group is preferred because it has a high ε and a high refractive index.

X is -C (CH ₃ ) _2- , -O-, -S- or
-NR _1- (R ₁ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a group -YOZ), and particularly -C (CH ₃ ) ₂
-Is preferred because of its excellent solubility in solvents.

Furthermore, An ^-, as the anion represented, for example, chlorine anion, bromine anion, iodine anion, a halogen anion such as fluorine anion; perchlorate anions, thiocyanate anions, hexafluorophosphate anions,
Inorganic anions such as antimony hexafluoride anion and boron tetrafluoride anion; or organic sulfonic acid anions such as benzenesulfonic acid anion, toluenesulfonic acid anion and trifluoromethanesulfonic acid anion; octyl phosphate anion and dodecyl phosphate anion; Organic anions such as organic phosphate anions such as octadecyl phosphate anion, phenyl phosphate anion and nonylphenyl phosphate anion, or, for example, those described in JP-A-60-234892 as quencher anions Is mentioned. Representative examples of the quencher anion include anions represented by the following general formulas (A) and (B).

[0024]

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Representative examples of the compound represented by the above general formula (I) include Φ-1 to Φ-1 shown in the following [Chemical Formula 8] to [Chemical Formula 19].
Φ-12 and the like. In the following examples, cyanine dye cations without anions are shown.

[0026]

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[0027]

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[0028]

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[0029]

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[0030]

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[0031]

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[0032]

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[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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The optical recording material of the present invention comprising the compound represented by the above general formula (I) is a salt of the above-mentioned cation and anion of a cyanine dye, and is obtained by condensing a 3-methylindolenine derivative with an aromatic aldehyde derivative. After the reaction, the compound can be easily synthesized by performing a salt exchange reaction.

Next, specific synthesis examples of the compound represented by the above general formula (I) will be described.

Synthesis Example 1 2- (di-n-butylaminophenyl-4'-vinyl)
-1- (4 "-nitrobenzyl) -3,3-dimethyl-
Production of 5-nitro-3H-indolenine perchlorate (perchlorate of Φ-1)

Round bottom 20 with thermometer, cooling pipe, nitrogen inlet pipe
In a 0 ml flask, add N- (4'-nitrobenzyl) -5
11.8 g of -nitro-2,3,3-trimethylindolenine bromide (Mw = 394) and 9.2 g of di-n-butylaminobenzaldehyde (Mw = 233) were added, and 79 g of isopanol was used as a solvent under a nitrogen stream. The reaction was performed at 82 ° C. for 2 hours. After completion of the reaction, 5.6 g of sodium perchlorate (Mw = 140.5) dissolved in 30 g of methanol was added, and the mixture was reacted at 65 ° C. for 30 minutes. After cooling, the precipitated crystals were collected by filtration, and the obtained crystals were recrystallized from 50 g of methanol to obtain 13.4 g (yield: 71%) of green crystals. λ _max = 595 nm
(Chloroform solution, the same applies hereinafter) ε = 1.68 × 10 ⁵
Met.

Synthesis Examples 2 to 12 Production of perchlorates of Φ-2 to Φ-12

Synthesis was carried out in the same manner as in Synthesis Example 1 except that the substituent used was a raw material (3-methylindolenine derivative and aromatic aldehyde derivative) corresponding to the structural formulas of Φ-2 to Φ-12. The [lambda] _max , [epsilon] and yield of each compound are shown in [Table 1] below.

[0044]

[Table 1]

The optical recording material of the present invention is applied to a recording layer of an optical recording medium, and a known method can be used for forming the recording layer. Generally, lower alcohols such as methanol and ethanol, ether alcohols such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, and butyl diglycol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and diacetone alcohol , Ethyl acetate, butyl acetate, esters such as methoxyethyl acetate,
Allyl esters such as ethyl acrylate and butyl acrylate, fluorinated alcohols such as 2,2,3,3-tetrafluoropropanol, hydrocarbons such as benzene, toluene, xylene, methylene dichloride, dichloroethane, chloroform, etc. Can be easily formed by applying a solution dissolved in an organic solvent such as chlorinated hydrocarbons on a substrate.

The thickness of the recording layer is usually 0.001 to
10 μ, preferably in the range of 0.01 to 5 μ. The method for forming the recording layer is not particularly limited, and an ordinary method such as a spin coating method can be used.

The content of the compound represented by formula (I) according to the present invention is preferably 5 to 100 parts by weight based on 100 parts by weight of the recording layer. In addition, the above general formula (I)
Other dyes can be used in combination with the compound represented by the formula: In this case, the weight ratio of the compound represented by the above general formula (I) according to the present invention to the other dye (former / latter)
Is preferably 5/95 to 100/0, more preferably 10/90 to 100/0. If the weight ratio is less than 5/95, the storage stability effect may be undesirably reduced.

The recording layer may contain, if necessary, resins such as polyethylene, polyester, polystyrene, and polycarbonate in addition to the compound represented by the general formula (I) according to the present invention. Well, also surfactant,
It may contain an antistatic agent, a lubricant, a flame retardant, a stabilizer, a dispersant, an antioxidant, a crosslinking agent, and the like.

Further, the recording layer may contain an aromatic nitroso compound, a transition metal chelate compound or the like as a quencher for singlet oxygen or the like. For these, known compounds such as those proposed in JP-A-59-55795 are used. The compound is used in an amount of preferably 0 to 50 parts by weight based on 100 parts by weight of the recording layer.

The material of the substrate on which such a recording layer is formed is not particularly limited as long as it is substantially transparent to writing light and reading light. Examples thereof include polymethyl methacrylate, polyethylene terephthalate, and polycarbonate. Resin, glass, etc. are used. Further, as the shape thereof, an arbitrary shape such as a tape, a drum, a belt or the like can be used according to the application.

A reflective film can be formed on the recording layer by vapor deposition or sputtering using gold, silver, aluminum, copper, or the like.
A protective layer made of an ultraviolet curable resin or the like can also be formed.

The optical recording material of the present invention comprises LD, CD, D
It can be used as a dye for optical disks such as VD, CD-R, and DVD-R, and particularly has a wavelength of 620 to 690 nm.
Is preferably used for an optical recording medium on which writing and reproduction are possible.
It is suitable for DVD-R using light having a wavelength of nm.

[0053]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited by the following examples.

Example 1 A titanium chelate compound (T-50: manufactured by Nippon Soda Co., Ltd.) was applied and hydrolyzed to form an underlayer (0.01 μm) having a diameter of 1 μm.
On a 2 cm polycarbonate disk substrate, an ethyl cellosolve solution of a dye mixed at a weight ratio shown in the following [Table 2] was applied by a spin coating method to give a thickness of 100%.
A recording layer of nm was formed.

Further, a gold reflective film of 100 nm was formed on the recording layer by an evaporation method.

Each medium created in this way is used for 3.6
While rotating at m / s, writing was performed from the back side of the substrate using a semiconductor laser (635 nm, light output of the condensing part 7 mW, frequency 2 KHz).

Next, the semiconductor laser (650 nm, output of the light condensing part: 0.1 mW) was used as readout light, the reflected light through the substrate was detected, and the C / N ratio was measured with a spectrum analyzer at a bandwidth of 30 KHz. .

A laser beam of 0.1 mW was used as readout light, irradiated with a pulse of 1 μsec and a pulse of 3 KHz for 5 minutes in a stationary state and at a temperature of 40 ° C. and a relative humidity of 88%.
After storing for 500 hours, the change (%) in the reflectance from the back side of the substrate was measured.

The results are shown in Table 2 below.

[0060]

[Table 2]

[0061]

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Example 2 A dye (Examples 2-1 to 2-12) in which Dye A and Dye Y shown in Table 3 below were mixed at a weight ratio of 1: 3, or Dye A alone (Example 2- Using 13), each medium was prepared in the same manner as in Example 1, and the refractive index (n) immediately after the preparation and after storage for 2000 hours under the conditions of 60 ° C. and a relative humidity of 88% was measured using a spectroscopic ellipsometer (M- 150, manufactured by JASCO Corporation. The results are shown in [Table 3].

[0063]

[Table 3]

[0064]

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As is clear from the above Examples, when the compound represented by the general formula (I) (asymmetric cyanine dye) according to the present invention was used, when the conventional cyanine dye was used (Comparative Example) Compared with 1-1), the writing sensitivity is excellent, the decrease in reflectance after irradiation and storage is extremely small (see Examples 1-1 to 1-8), and the change in refractive index is small (Example 2). -1 to 2-13), recording with extremely high reliability is possible.

[0066]

The optical recording material of the present invention has high sensitivity,
And excellent in light stability, storage stability and solubility in solvents,
Moreover, it is a cyanine dye having low crystallinity. Therefore, the optical recording material of the present invention is suitably used for an optical recording medium.

Claims (3)

[Claims] 1. An optical recording material comprising a compound represented by the following general formula (I). Embedded image Embedded image Embedded image 2. The optical recording material according to claim 1, wherein in the general formula (I), A is a nitro group. 3. The optical recording material according to claim 1, wherein the optical recording material is used for an optical recording medium capable of writing and reproducing at a wavelength of 620 to 690 nm.