JP2585056B2 - Optical information recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical information recording medium, and more particularly to a write-once optical information recording medium in a heat mode.

[Conventional technology]

2. Description of the Related Art A write-once optical recording medium in a heat mode has been used as a means for recording and reproducing data such as images such as characters and graphics or sound.

The write-once optical recording medium in this heat mode is created by vacuum-depositing a low-melting point metal such as tellurium on an insulating substrate. When recording on this, for example, a signal of an image taken by a camera is used. Is converted into an optical signal by, for example, a semiconductor laser or a helium / neon laser, and is radiated to a tellurium vacuum-deposited film to change the reflectivity of the film to form a pattern of the difference in reflectivity corresponding to an image. On the other hand, when the reading is performed, the difference in reflectance is detected by scanning with a weak laser beam, and this signal is converted into an image signal to display an image.

By the way, recently, instead of using a tellurium vapor deposition film as described above, organic dyes such as vanadyl phthalocyanine and cyanine dyes, which have a lower reflectance than metal but have relatively high reflectance among organic dye materials, are used for the recording layer. Optical information recording media have been attracting attention. The reason is that the recording layer can be formed by a coating method called spin coating, which uses a centrifugal force of rotation to spread the paint dropped on the substrate around the periphery, which makes it easy to manufacture without using a vacuum system, High productivity.Excellent oxidation resistance.No corrosion.Low thermal conductivity.Excellent properties such as local heating without affecting the surrounding area.Suitable for high density recording. It depends.

In particular, cyanine dyes have a wavelength range of 700
It is attracting attention because it shows high absorption and reflection at ~ 900 nm.

[Problems to be solved by the invention]

However, in conventional optical recording media having a cyanine dye-based recording layer on a plastic substrate, the most widely used semiconductor laser of 750 to 810 nm, such as a compact disk player, is used for reading on the plastic substrate when reading. No example has been known in which a material having a reflectance of 30% or more when reflected from a cyanine dye-based recording layer is used.

For example, the general formula [IV], which is generally well-known for its high reflectance, (However, R ₄ and R ₄ ′ represent an alkyl group, an alkoxy group, an alkylhydroxy group or an alkylcarboxyl group, and X ₃ ⁻ represents a halogen atom, perchloric acid, borofluoric acid, toluenesulfonic acid, alkylsulfonic acid or the like. For an optical recording medium having a recording layer provided on a plastic substrate using a cyanine dye represented by the following formula, the complex of the recording layer of light passing through this substrate is determined using the refractive index n (about 1.5) of the plastic substrate. When the refractive index n-ik is obtained, the reflectance of the recording layer is obtained therefrom, and when the film thickness of the recording layer is optimized so that the maximum reflectance is obtained, the wavelength showing the best reflectance is about 880 nm.
The reflectivity of a frequently used semiconductor laser of 780 to 790 nm is only about half of this.

When the reflectance is low as described above, an error is likely to occur due to a small servo signal, or a sufficient output may not be obtained due to a small reproduction signal. Also, sufficient C / N
There is a problem in that strict precision and changes must be required for the optical system and the electric system in order to achieve this.

In general, the pit shape when recording on the recording layer affects the C / N ratio and second harmonic distortion of the signal at the time of reading,
Although this leads to an increase in jitter and error rate, there is a problem that the jitter of the recording signal, which is considered to depend on the pit shape, is not good. Jitter refers to the distribution of the width of the shift on the time axis of a signal, and becomes larger when the edges of the pits of the recording layer are not sharp and are formed broadly. In the recording of digital information, the presence of this jitter causes an error, and it is desired to reduce this.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical information recording medium which enables the use of a cyanine dye-based recording layer having a high reflectance and has a small jitter depending on a pit shape.

[Means for solving the problem]

The present invention provides an optical information recording medium containing a compound represented by the following general formula [I] in order to solve the above problems.

(However, R ₁ and R ₁ ′ are an alkylene group having 1 to 5 carbon atoms, and R ₂ and R ₂ ′ are an alkyl group, an alkoxy group, an allyl group, a hydroxyalkyl group, a carboxyalkyl group, an amino group,
Dialkylamino, nitro, and aralkyl substituents; m and m ′ represent the number of these substituents;
1,2,3 is any of the integers may be the same or different, X ₁ ^- represents halogen, perhalogen acid, fluoroboric acid, toluenesulfonic acid, an anion of an alkylsulfonic acid . It is another object of the present invention to provide an optical information recording medium characterized in that the recording layer contains a compound represented by the following general formula [II].

(Provided that R ₃ and R ₃ ′ represent an alkylene group having 1 to 5 carbon atoms, Z and Z ′ represent a substituted or unsubstituted naphthalene ring, and X ₂ ⁻ represents halogen, perhalic acid, borofluoric acid, toluene Represents an anion of sulfonic acid or alkyl sulfonic acid, wherein the hydrogen atom on CH = CH ₂ may be substituted with a halogen atom or an alkyl group, and has a substituted or unsubstituted cyclic side chain extending over a plurality of carbon atoms. Next, the present invention will be described in detail.

In the present invention, the compound represented by the above general formula [I] is used, and specifically, the following compounds are exemplified in addition to those exemplified in Examples described later.

In the present invention, the compound represented by the above general formula [II] is used. When the methine chain has a cyclic side chain, the compound is bonded, for example, between the second and fourth carbons, and is, for example, a four-membered ring or a six-membered ring. A bonding chain consisting of carbon and other atoms forming a ring,
It may have a substituent. Examples of the substituent include a halogen atom, a diphenylamino group, an alkoxy group (for example, a lower alkoxy group such as methoxy and ethoxy), and an alkyl group (for example, a lower alkyl group such as methyl and ethyl). Specific examples include the following in addition to those exemplified in Examples described later.

In order to manufacture the optical information recording medium of the present invention, a dye solution in which each of the compounds represented by the general formulas (I) and (II) is dissolved is prepared and applied to a substrate. For example, chloroform, dichloroethane, methyl ethyl ketone, dimethylformamide, methanol, toluene, cyclohexanone, hydroxyacetone, acetylacetone, cellosolves such as methylcellosolve, dioxane and the like can be used. In this case, the mixing ratio of the cyanine dye is preferably 1% to 10%.

Further, the substrate used in the present invention is glass, epoxy resin, methacrylic resin, polycarbonate resin,
Polyester resin, polyvinyl chloride resin and the like can be used.

In addition, it is preferable to use a spin coating method to apply the above-mentioned dye solution to the substrate. In this case, a conventionally used thickness can be applied to the coating layer after drying.

In the present invention, a plurality of compounds of the general formulas [I] and [II] can be used in combination.

Further, in the present invention, an additive for improving characteristics as an optical information recording medium, a light absorbing agent for assisting light absorption, and the like may be used in the recording layer.

When used as an optical disc, a configuration having an air sandwich structure, a protective layer structure, or the like may be adopted.

〔Example〕

 Next, the present invention will be described in detail based on examples.

Example 1 3,3 '-(2-acetoxyethyl) 10-diphenylamino 9,11 ethylenethiadicarbocyanine perchlorate Was dissolved in methanol so as to be 4% by weight, and this coating liquid was applied to an injection-molded acrylic resin substrate with a pregroove using a spinner to form an optical recording layer of 700 °.

The disk on which this optical recording layer was formed was irradiated with a laser beam with a wavelength of 780 nm at an output of 3 mW on the recording surface and at a linear velocity of 1.2 m / sec.
The signal was recorded. The reflectivity of the mirror of this disk is 43
% And jitter were 24 ns.

Example 2 3,3'-di (3-acetoxypropyl) 5,6,5 ', 6'-
Tetramethoxythiadicarbocyanine toluenesulfonate Was dissolved in hydroxyacetone so as to be 4.5% by weight to prepare a coating solution. Using this coating solution, an optical recording layer was formed in the same manner as in Example 1.

When recording was performed on the disk having the optical recording layer formed thereon in the same manner as in Example 1, the reflectivity of the mirror portion was 39%, and the jitter was 25 ns.

Example 3 3,3'-diacetoxymethyl 6,7,6 ', 7'-dibenzothiazicarbocyanine iodide 4% by weight of nickel dithiobenzyltetrabutylammonium Was dissolved in methanol so as to have a concentration of 1% by weight to prepare a coating solution. Using this coating solution, an optical recording layer was formed in the same manner as in Example 1.

When recording was performed on the optical recording layer-formed disk in the same manner as in Example 1, the reflectance of the mirror portion was 40% and the jitter was 22 ns.

Comparative Example 1,1'-diethyl 3,3,3 ', 3'-tetramethylindotricarbocyanine perchlorate Was dissolved in ethanol so as to be 4.0% by weight to prepare a coating solution. Using this coating solution, an optical recording layer was formed in the same manner as in Example 1.

When recording was performed on the disk having the optical recording layer formed thereon in the same manner as in Example 1, the reflectance of the mirror portion was 28% and the jitter was 40 ns.

From the above results, it can be seen that the reflectivity and the jitter of the example of the present invention at the time of reproduction with a 780 nm laser are respectively superior to those of the comparative example, and the effect of using the compound represented by the above general formula is remarkably exhibited.

According to the present invention, it is possible to provide an optical information recording medium having a recording layer using the compounds represented by the above general formulas (I) and (II). Can be increased, thereby increasing the reproduced signal. In addition, jitter due to the pit shape can be reduced, and errors can be reduced.

In this way, an optical information recording medium can be manufactured by a simple method similar to the conventional method using an organic dye, and can be reproduced by the same simple reproducing device as a high-reflectance read-only disk. Value can be further increased.

Claims (2)

(57) [Claims] 1. An optical information recording medium comprising a recording layer containing a compound represented by the following general formula [I]. (However, R ₁ and R ₁ ′ are an alkylene group having 1 to 5 carbon atoms, and R ₂ and R ₂ ′ are an alkyl group, an alkoxy group, an allyl group, a hydroxyalkyl group, a carboxyalkyl group, an amino group,
Dialkylamino, nitro, and aralkyl substituents; m and m ′ represent the number of these substituents;
1,2,3 is any of the integers may be the same or different, X ₁ ^- represents halogen, perhalogen acid, fluoroboric acid, toluenesulfonic acid, an anion of an alkylsulfonic acid . ) 2. An optical information recording medium comprising a recording layer containing a compound represented by the following general formula [II]. (Provided that R ₃ and R ₃ ′ represent an alkylene group having 1 to 5 carbon atoms, Z and Z ′ represent a substituted or unsubstituted naphthalene ring, and X ₂ ⁻ represents halogen, perhalic acid, borofluoric acid, toluene Represents an anion of sulfonic acid or alkyl sulfonic acid, wherein the hydrogen atom on CH = CH ₂ may be substituted with a halogen atom or an alkyl group, and has a substituted or unsubstituted cyclic side chain extending over a plurality of carbon atoms. May be.)