JPH0749529B2 - Methine compound and optical recording medium containing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Purpose of the Invention (Field of Industrial Application) The present invention relates to a methine compound having a light-absorbing property and an optical recording medium using the compound.

(Prior Art) Optical recording using a laser beam or the like allows information to be recorded and stored at a high density and the recording can be easily reproduced and used, and an example thereof is an optical disk.

Generally, an optical disc is one in which a thin recording layer provided on a circular substrate is irradiated with a laser beam focused to about 1 μm to perform high density information recording. The recording is performed by the absorption of the irradiated laser light energy, which causes thermal deformation such as decomposition, evaporation, and dissolution in the recording layer at that location. The recorded information is reproduced by reading the difference in reflectance between the portion where the laser light is deformed and the portion where the deformation is not generated.

Therefore, the recording layer of the optical recording medium is required to efficiently absorb the energy of the laser beam, so that the absorption of the laser beam having a specific wavelength used for recording is large, and the information is accurately reproduced. It is necessary that the reflectance with respect to the laser light of the specific wavelength used for is high.

Conventionally, various types of optical recording media of this type have been known. For example, JP-A-55-97033 discloses a substrate in which a single layer of a phthalocyanine dye is provided. However, since the phthalocyanine dye has low sensitivity, has a high decomposition point, is difficult to be vapor-deposited, and has extremely low solubility in an organic solvent, it has a drawback that coating by coating for forming a recording layer is difficult. .

Further, JP-A-58-83344 and JP-A-58-224793 disclose that a recording layer is provided with a phenalene dye and a naphthoquinone dye, respectively. However, while these dyes have the advantage of being easily vapor deposited, they have the drawback of low reflectance. If the reflectance is low, the contrast of the reflectance between the recorded portion and the unrecorded portion due to the laser light becomes low, and it becomes difficult to reproduce the recorded information.

Further, JP-A-59-24692, JP-A-59-67092 and JP-A-59-71895 disclose a recording layer provided with a cyanine dye. However, although such a dye has an advantage that coating by coating is easy, it has a drawback that it is inferior in light resistance and deteriorates due to reproduction light.

(Problems to be Solved by the Invention) The present invention has high solubility in an organic solvent and high reflectance,
Another object of the present invention is to provide a novel light-absorbing methine compound having excellent light resistance and light resistance against reproduction light, and an optical recording medium having a recording layer containing the compound.

(B) Structure of the Invention (Means for Solving Problems) The methine compound of the present invention has the general formula (In the formula, R ¹ and R ² are each a hydrogen atom, a halogen atom,
Hydroxy group, alkyl group, alkoxy group, cyano group,
Represents an atom or group selected from a nitro group, an alkoxycarbonyl group, an aryloxycarbonyl group, a mono- or dialkylaminocarbonyl group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkoxycarbonyloxy group and an aryloxycarbonyloxy group, and A is It represents a residue obtained by removing one hydrogen atom from the aromatic ring of a substituted or unsubstituted aromatic amine. ) Is a compound represented by.

Further, the optical recording medium of the present invention is an optical recording medium having a substrate and a recording layer containing a light absorbing dye, and the light absorbing dye is represented by the general formula: (In the formula, R ¹ and R ² are each a hydrogen atom, a halogen atom,
Hydroxy group, alkyl group, alkoxy group, cyano group,
Represents an atom or group selected from a nitro group, an alkoxycarbonyl group, an aryloxycarbonyl group, a mono- or dialkylaminocarbonyl group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkoxycarbonyloxy group and an aryloxycarbonyloxy group, and A is It represents a residue obtained by removing one hydrogen atom from the aromatic ring of a substituted or unsubstituted aromatic amine. ) Is an methine compound represented by

Examples of the residue excluding one hydrogen atom in the aromatic ring of the substituted or unsubstituted aromatic amine represented by A in the general formula (I) include, for example, a heterocycle containing a nitrogen atom, an oxygen atom or a sulfur atom. Residues of amines, tetrahydroquinolines, or general formula (In the formula, X and Y are each a hydrogen atom, a halogen atom,
Alkyl group, acylamino group, alkoxycarbonylamino group, represents an atom or a group selected from an alkylsulfonylamino group and an alkoxy group, R ³ and R ⁴ are each a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, It represents an atom or group selected from a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group and a substituted or unsubstituted cyclohexyl group. ) And the like.

Examples of the substituent of the alkyl group, aryl group, allyl group or cyclohexyl group represented by R ³ or R ⁴ in the general formula (II) include an alkoxy group, an alkoxyalkoxy group, an alkoxyalkoxyalkoxy group, an allyloxy group and an aryl group. , Aryloxy group, cyano group, hydroxy group, tetrahydrofuryl group and the like.

The methine compound represented by the general formula (I) is 600 to 8
It has absorption in the wavelength band of 50 nm and has a molecular absorption coefficient of 10
^{It is 4} to 10 ⁵ cm ^-1 .

Among the methine compounds represented by the general formula (I), particularly preferred is the general formula [In the formula, R ¹ , R ² , X, Y, R ³ and R ⁴ are the same as defined in the general formula (I) or (II), respectively. ] It is a methylene type compound shown by these.

The methine compound represented by the general formula (III) has the general formula [In the formula, R ¹ and R ² are the same as defined in the general formula (I). ] The compound represented by [In the formula, X, Y, R ³ and R ⁴ are respectively the same as those defined in the general formula (II). ] It can manufacture by condensing with the cinnamic aldehydes shown by these.

Next, the optical recording medium of the present invention basically comprises a substrate and a recording layer containing the methine compound represented by the general formula (I). A pulling layer and a protective layer can be provided on the recording layer.

The substrate in the present invention may be transparent or opaque to the laser light used. As the material of the substrate, a general support for this type of recording medium such as glass, plastic, paper, plate-shaped or foil-shaped metal can be used, but plastic is preferable from various points. Examples of the plastic include acrylic resin, methacrylic resin, vinyl acetate resin, vinyl chloride resin, nitrocellulose, polyethylene resin, polypropylene resin,
Examples thereof include polycarbonate resin, polyimide resin, polysulfone resin, and epoxy resin.

The thickness of the recording layer containing the methine compound in the optical recording medium of the present invention is 100Å to 5 μm, preferably 500Å to 3
μm.

As a film forming method for forming the recording layer, a vacuum vapor deposition method,
Sputtering method, doctor blade method, casting method,
A commonly used thin film forming method such as a spinner method or a dipping method is used.

To form the recording layer, a binder can be used in combination with the methine compound, and as the binder, resins such as polyvinyl alcohol, polyvinylpyrrolidone, nitrocellulose, cellulose acetate, polyvinyl butyral, and polyvinyl carbonate are used. The amount of these resins used is preferably 0.1% by weight or more based on the weight of the methine compound.

Doctor blade method, casting method, spinner method,
A coating solvent is used when the recording layer is formed by the dipping method, especially the spinner method, and examples of the solvent include tetrachloroethane, bromoform, dibromoethane, ethyl cellosolve, xylene, chlorobenzene, and cyclohexanone having a boiling point of 120 to 160. Solvents at ° C are preferably used.
In addition, the film formation by the spinner method is preferably performed at a rotation speed of 500 to 5000 rpm, and after spin coating, a treatment such as heating or exposure to a solvent vapor may be performed depending on the case.

In order to improve stability and light resistance of the recording layer, a transition metal chelate compound (for example, acetylacetonate chelate, bisphenyldithiol, salicylaldehyde oxime, bisdithiol-α-diketone, etc.) is used as an entity of singlet oxygen in order to improve stability and light resistance of the recording layer. ) Or a tertiary amine compound may be contained.

Furthermore, other dyes can be used in combination in the recording layer, if desired. Other dyes include naphtholactam dyes, triarylmethane dyes, azo dyes, cyanine dyes, squarylium dyes, indoaniline dyes,
Examples thereof include naphthalocyanine dyes, phthalocyanine dyes, and metal-containing azo dyes.

The recording layer in the optical recording medium of the present invention may be provided on both sides of the substrate, or may be provided on only one side.

Recording on the optical recording medium of the present invention is carried out by using a laser beam focused to about 1 μm on a recording layer provided on both sides or one side of a substrate,
It is preferably performed by applying a semiconductor laser beam. In the portion irradiated with the laser light, thermal deformation of the recording layer such as decomposition, evaporation and melting due to absorption of laser light energy occurs, and information is recorded.

Reproduction of the recorded information is performed by reading the difference in reflectance between a portion where thermal deformation has not occurred and a portion where thermal deformation has occurred, with a laser beam.

As a laser used for recording and reproducing of the optical recording medium of the present _{invention, N 2, He-Cd,} Ar, He-Ne, ruby, semiconductor, but such a dye laser and the like, in particular light weight, easy to handle the A semiconductor laser is preferable from the viewpoint of compactness.

(Example) An example is given below and further detailed.

Example 1 Methine compound: Structural formula 12 g of the compound represented by 98 g of the compound shown in the above are added to a solution consisting of 250 g of glacial acetic acid and 50 g of acetic anhydride, and the reaction is carried out by stirring at 100 to 105 ° C. for 4 hours. Stir for hours. Take the resulting precipitate as crystals,
After drying, 16 g of a methine compound (black green crystal) having the following structural formula was obtained. Solution of this compound (chloroform)
The λ _max therein was 700 nm.

The characteristic values of this compound are as follows.

Melting point 191-192 ° C Mass spectrum value m / e 483 (M ⁺ ) 413 (M ⁺ −70) Molecular extinction coefficient ε (in chloroform) 8.0 × 10 ⁴ Optical recording medium: 1 g of the methine compound obtained as described above was dissolved in 50 g of tetrachloroethane and filtered through a 0.22 μm filter to obtain a solution. 2 ml of this solution was dropped onto a methacrylic resin (hereinafter referred to as “PMMA”) substrate (120 mmφ) having a depth of 700 Å and a width of 0.7 μm of an ultraviolet curable resin, and spun at 1200 rpm by a spinner method. After coating with a number, it was dried at 60 ° C. for 10 minutes. The maximum absorption wavelength of the coating film is
It was 695 nm, and the shape of the spectrum was wide. Also,
The absorbance and reflectance curve of the coating film are as shown in the attached drawing, the reflectance peak was at 840 nm, and the reflectance at 840 nm was 46%.

The center wavelength of 78 is applied to the coating film (recording layer) of the obtained optical recording medium.
When a semiconductor laser beam of 0 nm (output 6 mW, beam 1 μm) was irradiated, extremely clear holes (pits) having a width of about 1 μm and a pit length of about 2 μm were formed. The carrier level / noise level (C / N) ratio was high, and light resistance and reproduction light resistance were also good.

Example 2 Methine compound: By the method according to the production method in Example 1, the structural formula A methine compound represented by The characteristic values of this compound are as follows.

λ _max (chloroform) 715 nm Melting point 178-179 ° C Mass spectrum m / e 497 (M ⁺ ) 427 (M ⁺ -70) Molecular extinction coefficient ε (in chloroform) 9.2 × 10 ⁴ Optical recording medium: 1 g of the above-mentioned methine compound and 1.5 g of nitrocellulose (trade name RS-20 from Daicel Chemical Industries, Ltd.) were dissolved in 50 g of methyl ethyl ketone to obtain 0.22 μm. The solution was filtered through. 3 ml of this solution, depth 650Å, width 0.7 μm
Was dripped onto a PMMA resin substrate (120 mmφ) having grooves (groups) made of the UV curable resin, and applied at a rotation speed of 1500 rpm, and then dried at 60 ° C. for 10 minutes.

The maximum absorption wavelength of the coating film was 650 nm, and the peak was broad. Also, the maximum reflectance of this coating film is 40 at 850 nm.
%Met.

The center wavelength of 78 is applied to the coating film (recording layer) of the obtained optical recording medium.
When a 0 nm semiconductor laser beam (output 6 mW, beam diameter 1 μm) was irradiated, extremely clear holes (pits) having a width of about 1 μm and a pit length of about 2 μm were formed. Its C / N ratio was high, and its light resistance and reproduction light resistance were good.

Example 3 Methine compound: By the method according to the production method in Example 1, the structural formula A methine compound represented by Λ _{max of} this compound
(Chloroform) was 700 nm.

Optical recording medium: 1 g of the above-mentioned methine compound was dissolved in 50 g of dibromoethane and passed through a 0.22 μm filter to obtain a solution. 2 ml of this solution was dropped on a PMMA resin substrate (130 nmφ) having a groove (groove) made of an ultraviolet curable resin with a depth of 700 Å and a width of 0.7 μm, applied at a rotation speed of 800 rpm, and then dried at 60 ° C. for 20 minutes. . The maximum absorption wavelength of the obtained coating film was 695 nm, and the peak was broad.

When the obtained optical recording medium (coating film) was irradiated with a semiconductor laser beam having a center wavelength of 780 nm (output 6 mW, beam diameter 1 μm), a very clear hole (pit) with a width of about 1 μm and a pit length of about 2 μm was formed. Was formed. Its C / N ratio was high, and its light resistance and reproduction light resistance were also good.

Examples 4 to 89 General formula And various methine compounds shown in Table 1 were produced by a method similar to the production method in Example 1. The maximum absorption wavelengths of the obtained methine compounds in chloroform solvent are shown in Table 1, respectively.

Further, each of the methine compounds was coated on a PMMA resin substrate having a groove under the same conditions as in Example 1 to manufacture an optical recording medium. In each of the obtained optical recording media, the spectral peak of the recording layer (coating film) was broad, and the maximum absorption wavelength was as shown in Table 1.

When each of the recording layers was irradiated with a semiconductor laser beam having a central wavelength of 780 nm, holes (pits) with extremely clear contours were formed, high reflectance, high sensitivity and excellent C / N ratio. Further, their light resistance and resistance to reproduction light were also good.

(C) Effects of the Invention The methine compound of the present invention is remarkably excellent in solubility in an organic solvent, has high reflectance, and is excellent in light resistance. Therefore, the optical recording medium of the present invention using this compound is
The recording layer can be easily formed by a solvent solution coating method, the contrast of the recording layer is good, and the light resistance and the reproduction light resistance are excellent.

[Brief description of drawings]

The accompanying drawings show the absorbance and reflectance curves of the recording layer obtained in Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junko Nakakuki 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Sanryo Kasei Kogyo Co., Ltd. (56) Reference JP-A-61-63846 (JP, A) Kaisho 62-295963 (JP, A)

Claims (4)

[Claims] 1. A general formula (In the formula, R ¹ and R ² are each a hydrogen atom, a halogen atom,
Hydroxy group, alkyl group, alkoxy group, cyano group,
Represents an atom or group selected from a nitro group, an alkoxycarbonyl group, an aryloxycarbonyl group, a mono- or dialkylaminocarbonyl group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkoxycarbonyloxy group and an aryloxycarbonyloxy group, and A is It represents a residue obtained by removing one hydrogen atom from the aromatic ring of a substituted or unsubstituted aromatic amine. ) A methine compound represented by 2. A in the general formula is a general formula (In the formula, X and Y are each a hydrogen atom, a halogen atom,
Represents an atom or a group selected from an alkyl group, an acylamino group, an alkoxycarbonylamino group, an alkylsulfonylamino group and an alkoxy group, R ³ and R ⁴ are each a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. Represents an atom or group selected from a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group and a substituted or unsubstituted cyclohexyl group. ] The methine compound of Claim 1 which is a group shown by these. 3. In an optical recording medium having a substrate and a recording layer containing a light absorbing dye, the light absorbing dye has the general formula (In the formula, R ¹ and R ² are each a hydrogen atom, a halogen atom,
Hydroxy group, alkyl group, alkoxy group, cyano group,
Represents an atom or group selected from a nitro group, an alkoxycarbonyl group, an aryloxycarbonyl group, a mono- or dialkylaminocarbonyl group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an alkoxycarbonyloxy group and an aryloxycarbonyloxy group, and A is It represents a residue obtained by removing one hydrogen atom from the aromatic ring of a substituted or unsubstituted aromatic amine. ) An optical recording medium characterized by being a methine compound represented by: 4. A in the general formula is a general formula (In the formula, X and Y are each a hydrogen atom, a halogen atom,
Represents an atom or a group selected from an alkyl group, an acylamino group, an alkoxycarbonylamino group, an alkylsulfonylamino group and an alkoxy group, R ³ and R ⁴ are each a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms. Represents an atom or group selected from a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group and a substituted or unsubstituted cyclohexyl group. The optical recording medium according to claim 3, which is a group represented by: