JP2000289335A - Optical recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the optical stability, preservability and solvent solubility and enhance the coloring sensitivity by arranging a coloring recording layer containing a chemical compound comprising an indolenine cyanine coloring matter represented by a specific formula and a substituting group donated to the former, on a substrate. SOLUTION: A coloring layer is formed on a substrate and at the same time, a chemical compound represented by the formula (wherein, m is an integer of 0-2; n is an integer of 1-3; R1 is a 1-4C alkylene group; R2 is a 0-4 substituted phenyl group having a nitro group, cyano group, halogen atom, a 1-8C alkyl group, alkoxy group, alkenyl group or alkenyloxy group as substituting groups, or the like; and An- is anion.) is added to the color developing layer to prepare an optical recording material. The preferably applicable anion represented by An- is a chlorine action, a bromine action or the like. The chemical compound represented by 1 as (n) in the formula shows a sensitivity of 620-690 nm wavelengths for writing and regeneration.

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 is characterized in that the recording medium does not wear and deteriorate because the recording and reading heads do not come into contact with the medium. The optical recording medium provided as has the advantage that development processing in a dark room is not required, and therefore its development is actively conducted.

[0003] Such an optical recording medium utilizes 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.

Writing information on a recording medium is performed by scanning a laser beam converged on the surface of the recording layer and forming pits in the recording layer absorbing 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 material such as a metal thin film such as an aluminum vapor-deposited film, a tellurium oxide thin film, a bismuth thin film, and 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, the operation is complicated, and when the above-mentioned inorganic material is used, It has drawbacks such as high reflectance to laser light, high thermal conductivity, and low utilization efficiency 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, thioxazole type, quinoline type and selenazole type are known. These dyes are salts of a cyanine dye cation and various anions such as a halogen anion and a perchlorate anion. In particular, indolenine dyes are preferably used because of their high sensitivity.

An optical recording medium using such a dye has a wavelength of 770 to 770 corresponding to the compact disk (CD) standard.
An optical recording medium (CD-R) that can be written and reproduced by an 830 nm near-infrared semiconductor laser has been put to practical use.

[0010] Recently, 62 wavelengths shorter than 770 nm have been used.
A red semiconductor laser having a wavelength of 0 to 690 nm has been developed. The recording density has been increased by making the beam spot smaller, and a large-capacity optical recording medium (digital versatility disc) capable of recording moving images by using data compression technology or the like. , DVD) have also been developed.

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

For example, a dye used for an optical recording medium which performs writing at 635 nm and uses 650 nm for reading has sensitivity for writing at 635 nm and high reflectance at 650 nm, that is, molecular absorption. A large coefficient is desirable.

[0013] As a dye corresponding to writing with a red semiconductor laser of 620 to 690 nm, for example, an optical recording medium using an indcarbocyanine dye in a recording layer has been proposed in JP-A-59-55795. I have.

However, in these dyes, the aforementioned D
It could not be said that it exactly matched the absorption wavelength of the VD-R standard, and the reflectance was not sufficient.

Accordingly, an object of the present invention is to provide an optical recording material which is used in a recording layer of an optical recording medium, has good light stability, storage stability and solubility in a solvent, and has high sensitivity. Is to do.

[0016]

As a result of repeated studies, the present inventors have found that a compound in which an indolenine-based cyanine dye has a specific substituent can achieve the above object.

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) of the following [formula 2] (same as the above [formula 1]). It provides a recording material.

[0018]

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[0019]

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) according to the present invention is a dye used in a recording layer of an optical recording medium.

In the above general formula (I), the alkylene group having 1 to 4 carbon atoms represented by R ₁ includes, for example, methylene, ethylene, propylene, 1-methylethylene, 2-methylethylene, butylene And the like.
Examples of the alkyl group having 1 to 8 carbon atoms, which is a substituent in ₂ , include methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, isobutyl, amyl, tertiary amyl, hexyl, and heptyl. Octyl, isooctyl, tertiary octyl, 2-ethylhexyl, and the like. Examples of the alkoxy group having 1 to 8 carbon atoms include groups derived from the above alkyl groups, and alkenyl groups having 1 to 8 carbon atoms. Examples thereof include vinyl, propenyl, isopropenyl, butenyl, octenyl and the like. Examples of the alkenyloxy group having 1 to 8 carbon atoms include groups derived from the above alkenyl groups.
Examples of the halogen atom as a substituent in ₂ include fluorine, chlorine, bromine, and iodine. As R ₂ represented by an alkyl group having 1 to 4 carbon atoms, methyl, ethyl, propyl, isopropyl, and butyl , Sec-butyl, tert-butyl,
Examples include isobutyl, and examples of the alkenyl group having 1 to 4 carbon atoms include vinyl, propenyl, isopropenyl, and butenyl.

[0022] An ^- as the anion represented by, for example, chlorine anion, bromine anion, iodine anion, a halogen anion such as fluorine anion, perchloric acid anion, thiocyanate anion, hexafluorophosphate anion, antimony hexafluoride Anions, inorganic anions such as boron tetrafluoride anion, or organic sulfonic acid anions such as benzenesulfonic acid anion toluenesulfonic acid anion and trifluoromethanesulfonic acid anion; octyl phosphate anion, dodecyl phosphate anion, octadecyl phosphate anion; Organic anions such as organic phosphate anions such as phenyl phosphate anion and nonylphenyl phosphate anion, or, for example, anions such as those described in JP-A-60-234892 as quencher anions. It is. Representative examples of the quencher anion include anions represented by the following general formulas (A) and (B).

[0023]

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In the general formula (I), n represents an integer of 1 to 3, and a compound in which n is 1 is particularly preferable because it has excellent sensitivity to a wavelength of 620 to 690 nm for writing and reproducing. .

As typical examples of the compound represented by the above general formula (I), the following compound No. 1 to 13 and the like. In the following examples, the 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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[0038]

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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 the cyanine dye, and can be produced according to a conventionally known method.

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

(Synthesis Example 1) Synthesis of Phosphorus hexafluoride No. 6 15.3 g of 4-nitrophenylhydrazine in a round-bottomed 500 ml flask equipped with a thermometer, cooling tube and nitrogen inlet tube
(0.10 mol), 30.0 g of acetic acid (0.50 mol
l) and charged at 80 ° C with 3-methyl-2-pentanone 1
0.0 g (0.10 mol) was added dropwise, and the temperature was raised to 100 ° C. While paying attention to heat generation, 19.6 g of concentrated sulfuric acid (0.
20 mol) was slowly added dropwise, and the mixture was refluxed for 1 hour after the completion of the addition. After cooling, 24.3 g of 28% by weight ammonia water,
After neutralization with 16.0 g of a 10% by weight aqueous sodium hydroxide solution, 100 ml of toluene and 100 ml of water were added to perform oil / water separation. The toluene layer was washed three times with water, dehydrated with anhydrous sodium sulfate, concentrated, and purified with silica gel and hexane / ethyl acetate = 1/1 (by weight) column to purify 2,3-
Dimethyl-3-ethyl-5-indolenine 10.0 g
(46% yield).

In a 200 ml flask, the 2,
3-dimethyl-3-ethyl-5-indolenine 10.0
g (0.039 mol), 12.2 g of 4-chlorobenzenesulfonic acid phenoxyethyl ester (0.039 m
ol), and reacted at 135 ° C. for 1 hour. Then, 50 g of ethyl acetate was added for crystallization. The crystals were collected by filtration, washed, and dried in vacuo to obtain 5.7 g (28%) of pale brown crystals.

5.3 g of the intermediate obtained in a 100 ml flask, 0.98 g of N, N-diphenylformamide
(0.0050 mol), pyridine 15.8 g (0.2
0 mol) and 5.1 g (0.050 mol) of acetic anhydride, and reacted at 115 to 120 ° C. for 2 hours. 3.6.9 g of dimethylformamide and potassium potassium hexafluoride
After adding 7 g and making it react at 100 degreeC for 1 hour, 50 g of chloroform and 50 g of water were added and oil-water separation was performed. The chloroform phase was washed twice with water and dried over anhydrous sodium sulfate.
The concentrate was purified by column purification using silica gel and an ethyl acetate solvent, and the purified product was recrystallized from dimethylformamide / methanol = 10.6 / 42.4 (weight), and the obtained crystals were washed and dried. 0.57 g (yield 14.0%) of green crystals as the target compound was obtained.

The following results were obtained as optical characteristics of the obtained crystal. Λmax (chloroform solution, the same applies hereinafter) = 579.0
nm · ε (molar extinction coefficient at λmax, the same applies hereinafter) = 2.
10 × 10 ⁵

As in the above (Synthesis Example 1), Compound No.
2 to 5 phosphorus hexafluoride salts are synthesized, and λ
max and ε were measured. The results are shown in Table 1 below.

[0046]

[Table 1]

The optical recording material of the present invention is applied as a recording layer of an optical recording medium, and can be formed by a conventionally known method. Generally, methanol,
Lower alcohols such as ethanol, methyl cellosolve,
Ether alcohols such as ethyl cellosolve, butyl cellosolve, and butyl diglycol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and diacetone alcohol; ethyl acetate;
Esters such as butyl acetate and methoxyethyl acetate, acrylates such as ethyl acrylate and butyl acrylate, fluorinated alcohols such as 2,2,3,3-tetrafluoropropanol, benzene, toluene, xylene and the like It can be easily formed by applying a solution dissolved in an organic solvent such as hydrocarbons, chlorinated hydrocarbons such as methylene dichloride, dichloroethane and chloroform onto a substrate. That is, an optical recording medium in which a thin film made of the compound represented by the general formula (I) is formed as a recording layer on a substrate can be formed.

The thickness of the recording layer is usually from 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 a commonly used method such as a spin coating method can be used.

When the optical recording material of the present invention is contained in a recording layer of an optical recording medium, the amount used for the recording layer is preferably 50 to 100% by weight.

The recording layer may contain, in addition to the optical recording material of the present invention, if necessary, resins such as polyethylene, polyester, polystyrene and polycarbonate. , Lubricants, flame retardants,
It may contain 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. As these compounds, for example, known compounds as proposed in JP-A-59-55795 are used. The compound is
It is preferably used in the range of 0 to 50% by weight based on 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. In addition, any shape such as a tape, a drum, a belt, and a disk can be used depending on 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 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.
It is suitable for a DVD-R using light having a wavelength of 90 nm.

[0055]

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

Example 1 Titanium chelate compound (T-
50: Nippon Soda Co., Ltd.) was applied and hydrolyzed on a polycarbonate disk substrate having a diameter of 12 cm and provided with an underlayer (0.01 μm), and a dye and an aromatic nitroso compound (DQ-24) shown in Table 2 below were formed. : Asahi Denka Kogyo Co., Ltd.)
Of a 0.10.1 (weight ratio) ethyl cellosolve solution was applied by a spin coating method to form a recording layer having a thickness of 100 nm, and a 100 nm gold reflective film was further formed on the recording layer by an evaporation method. Formed. Writing is performed from the back side of the substrate using a semiconductor laser (635 nm, output of a light-collecting unit 7 mW, frequency 2 kHz) while rotating each medium thus created at 3.6 m / s. 650 nm, a light output of a light condensing part of 0.1 mW) was used as readout light, reflected light through the substrate was detected, and the C / N ratio was measured with a spectrum analyzer at a bandwidth of 30 kHz. Also, a 0.1 mW laser is used as readout light,
After irradiation for 5 minutes in a stationary state as a pulse of 1 μsec width and 3 kHz, and 25 ° C. at 40 ° C. and 88% relative humidity.
After storage for 00 hours, the change (%) in reflectance from the back side of the substrate was measured. The results are shown in Table 2 below.

[0057]

[Table 2]

Example 2 Each medium was prepared in the same manner as in Example 1 using the dyes shown in Table 3 below, and the refractive index was measured using a spectroscopic ellipsometer (M-150, manufactured by JASCO Corporation). (N) and extinction coefficient (k) were measured. The results are shown in Table 3 below.

[0059]

[Table 3]

Example 3 Each medium was prepared in the same manner as in Example 1 using the dyes shown in Table 4 below, and a xenon weather resistance tester (Tablesun, manufactured by Suga Test Machine Co., Ltd.) was used. The sample was irradiated with light of 50,000 lux, and the half-life of the absorbance at λmax (the time required for the absorbance at λmax to decrease to 50% when the medium was prepared) was measured. The results are shown in Table 4 below.

[0061]

[Table 4]

As is clear from the above examples, when the optical recording material of the present invention comprising the compound represented by the general formula (I) was used, compared with the case where a conventional cyanine dye was used, Since the writing sensitivity is excellent, the decrease in reflectance after irradiation and storage is extremely small, and the balance between n and k is excellent, extremely reliable recording can be performed.

[0063]

The optical recording material of the present invention has good light stability, storage stability and solubility in a solvent, and has high sensitivity.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Atsuro Tomita 5-2-113 Shirahata, Urawa-shi, Saitama Asahi Denka Kogyo Co., Ltd. (72) Inventor Tohru Yano 5-2-13-Shirahata, Urawa-shi, Saitama Asahi F-term (reference) in Denka Kogyo Co., Ltd. 2H111 EA03 EA12 EA22 EA33 EA39 EA40 FB43 5D029 JA04 JC17

Claims (2)

[Claims] 1. An optical recording material comprising a compound represented by the following general formula (I). Embedded image 2. An optical recording medium wherein a thin film made of the compound represented by the above general formula (I) is formed on a substrate.