JPH059275B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a recording method for a write-once optical information recording medium using a heat mode. [Prior Art] As a means for recording and reproducing data such as images such as characters and figures or sounds, heat mode write-once optical recording media are used. This heat mode write-once optical recording medium is
For example, it is created by vacuum-depositing a low-melting point metal such as tellurium on an insulating substrate, and when recording on this, the signal of the image taken with a camera is transferred to, for example, a semiconductor laser or a helium or neon laser. etc., and irradiates the vacuum-deposited tellurium film to change the reflectance of the film to form a pattern of differences in reflectance corresponding to the image signal. On the other hand, when reading out the data, 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. Incidentally, recently, instead of using the vapor-deposited film of tellurium as described above, organic dyes such as vanadyl phthalocyanine and cyanine dyes, which have lower reflectance than metals but relatively high reflectance among organic dye materials, have been used in the recording layer. Optical information recording media, which used to be popular in the past, are now attracting attention. The reason for this is that the recording layer can be formed using a coating method called spin coating, which uses the centrifugal force of rotation to spread the paint dripped onto the substrate over the surrounding area.This makes it easy to manufacture without using a vacuum system. It has excellent properties such as being able to increase productivity, being resistant to oxidation and not corroding, and being able to heat locally without affecting the surrounding areas due to its low thermal conductivity, making it suitable for high-density recording. It depends. In particular, cyanine dyes have attracted attention because they exhibit high absorption and reflection in the wavelength range of 700 to 900 nm of semiconductor laser light. [Problem to be solved by the invention] However, in optical information recording media that have a conventional organic dye-based recording layer on a plastic substrate, research has mainly focused on optical properties and stability for recording and reading information. However, it has not yet been elucidated that the recording characteristics depend on the thermal characteristics, and that the recording characteristics can also be improved by improving the thermal characteristics. In general, the pit shape when recording on a recording layer affects the C/N ratio and second harmonic distortion of the signal when reading, leading to an increase in jitter and error rate. Therefore, it is desired to have a pit shape that does not lead to an increase in jitter or error rate, but conventional pit shapes are still insufficient. The principle of write-once optical recording by drilling is based on the fact that light absorbed by the recording layer is converted into heat, and the heat changes the recording material to form pits. Therefore, recording characteristics can be improved by controlling the thermal characteristics of the recording layer. However, it is generally difficult to design the thermal properties of recording materials, and in the case of optical recording materials, methods such as changing the molecular weight of organic dyes or adding elemental compounds that cause endothermic or exothermic reactions at specific temperatures are considered. However, this is not easy either. An object of the present invention is to provide an optical information recording medium in which the pit shape during recording is improved by improving the thermal characteristics of the recording layer by a simple means, and thereby the jitter and error rate are improved. [Means for Solving the Problems] In order to solve the above problems, the present invention employs a spin coating method on the surface of a substrate using a dye solution containing an organic dye and a solvent that solvates the organic dye. In a recording method for an optical information recording medium, the information is recorded on the recording layer by forming a recording layer by irradiating the recording layer with a laser beam, and the information is recorded without any drying process other than the spin coating method described above. Recording of an optical information recording medium, characterized in that recording is performed in a state in which the initial solvation of the organic dye is retained in the recording layer formed by setting the boiling point of the solvent to 80°C to 160°C. The present invention provides a method. Next, the present invention will be explained in detail. In the present invention, information is recorded by irradiating laser light on a recording layer in which a solvent is solvated with an organic dye, and in this recording layer, for example, a polar solvent is strongly bonded to a polar organic dye. Even at temperatures exceeding the boiling point of the solvent, the solvent remains and has a large effect on the thermal reaction caused by the light absorbed by the organic dye. As the organic dye used in the present invention, polar dyes such as cationic dyes and anionic dyes are preferable, and cyanine dyes such as indolenine dyes and thiazole dyes, merocyanine dyes, squarylium dyes, pyrylium dyes, etc. are particularly preferable. , but not limited to these. Specifically, in addition to those shown in the examples below, the following are exemplified. Indolenine cyanine pigment Thiazole cyanine dye However, in the above formula ()(), R ₁ , R ₂
and R ₃ may be the same or different, each represents a C ₁ to _{C 6} alkyl group, X represents halogen, perhalogen acid, boron tetrafluoride, toluenesulfonic acid or alkyl sulfuric acid, and A represents a benzene ring or a naphthyl ring, and each ring has alkyl, alkoxy,
Hydroxy, carboxyl, halogen, allyl or alkylcarboxyl may be present or absent, and n represents 0 or an integer from 1 to 3. Furthermore, each carbon forming the methine chain may be substituted with an alkyl group or a halogen atom, and each carbon may be cyclically bonded with a saturated hydrocarbon. Moreover, X may be a metal complex anion shown below. However, in the above formulas () to (), M is
represents a transition metal such as Ni, Co, Mn, Cu, Pd and Pt, R ₁ to R ₄ may be the same or different, and each represents a substituted or unsubstituted alkyl, aryl or amino group; R ₅ to R ₁₂
may be the same or different, and each represents a hydrogen atom, a halogen atom, or a substituted or unsubstituted alkyl, acyl, alkoxy, acyloxy,
represents an aryl, alkenyl or amino group, R ₁₃
represents a substituted or unsubstituted amino group, l,
m, n, p, q and r represent 0 or 1-4, and u and v represent 0 or 1-2. polymethine dye However, in the above formulas () to (), A,
B, D and E represent substituted or unsubstituted aryl groups, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ and R ₇ may be the same or different, and each represents hydrogen. atom, halogen atom or alkyl group, Y is 5
Indicates a divalent residue having the atomic group necessary to complete a membered ring or a 6-membered ring, R ₈ and R ₉ may be the same or different, and each represents a substituted or unsubstituted alkyl group. , represents a substituted or unsubstituted aralkyl group or alkenyl group, Z ₁ and Z ₂ represent the atomic group necessary to complete the substituted or unsubstituted heterocycle, and Z ₃ represents a substituted or unsubstituted 5-membered ring. or indicates the atomic group necessary to complete the 6-membered ring,
Further, the above 5-membered ring or 6-membered ring may be fused with an aromatic ring, R ₁₀ represents a hydrogen atom or a halogen atom, and R ₁₁ and R ₁₂ represent a hydrogen atom, a halogen atom,
It represents a hydroxy group, a carboxyl group, an alkyl group, a substituted or unsubstituted aryl group or an acyloxy group, and l, m and n are 0 or 1. Triarylmethane dye However, in the above formulas () and (), R ₁ , R ₂ and R ₃ may be the same or different, and each is a hydrogen atom, hydroxy, a halogen atom, a C ₁ to C ₂₀ alkyl group, or -N ( _C1 - _C10 alkyl) ₂ , l, m and n represent 0 or 1-9, _Ar1 , _Ar2 and _Ar3 may be the same or different, and each may be substituted or unsubstituted. represents a substituted aryl group, s, t and u represent 0 or 1 to 3,
And s+t+u=3. pyrylium pigment However, in the above formulas () and (), X, X ₁ and X ₂ represent a sulfur atom, an oxygen atom or a selenium atom, and Z and Z ₁ are optionally substituted pyrylium, thiopyrylium, selenapyrylium, benzene Pyrylium, benzothiopyrylium,
Indicates a hydrocarbon group consisting of the atomic group necessary to complete benzoselenapyrylium, naphtopyrylium, naphthothiopyrylium, or naphthoselenapyrylium, and Z ₂ is optionally substituted pyran, thiopyran, selenapyran, penzopyran, penzothiopyran, benzoselenapyran, naphthopyran,
Indicates a hydrocarbon group consisting of the atomic group necessary to complete naphthothiopyran or naphthoselenapyran, and R ₁ , R ₂ , R ₃ and R ₄ are hydrogen atoms, substituted or unsubstituted alkyl groups, or substituted or unsubstituted alkyl groups. Represents an aryl group, R ₅ , R ₆ and R ₇ are hydrogen atoms,
It represents a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, m and l represent 1 or 2, and n represents 0, 1 or 2. phenanthrene dye However, in the above formulas () and (), R ₁ and R ₂ represent an alkyl group, and R ₃ , R ₄ and
R ₅ represents a hydrogen atom, hydroxy, halogen atom, substituted or unsubstituted alkyl, aryl, aralkyl, amino or alkoxy group, and R is

[Formula]-0-R ₁ ,

[Formula] and l, m and n represent 0 or 1-6. Tetrahydrocholine dye However, R ₁ represents alkyl, carbalkoxy such as COOC ₂ H ₅ , R ₁ represents hydrogen, an alkyl group, etc., and M represents H, Ni(), Co(),
Represents Co(), etc. Triarylamine dye However, R ₁ to _{R 3} , l, m, n, Ar ₁ to Ar ₃ , s, t, and u in the above formulas () and () are the same as described for the above formulas () and (). As a counter ion for the dye cation in () to () listed in ~,
Acid anions such as chloride, bromide, iodide, perchlorate, benzenesulfonate, p-toluenesulfonate, methylsulfate, ethylsulfate, propylsulfate, etc. There is. squarylium pigment However, in formula () (), A is hydrogen,
Halogen atom, alkyl group, alkoxy group, nitro group, cyano group, trifluoromethyl group,

[Formula], n is an integer from 0 to 5, and when n is 2 to 5, A may be the same or different. Furthermore, Y represents hydrogen, an alkyl group, a halogen atom, or a hydroxyl group, and R ₁ and R ₂ represent an alkyl group, a phenyl group that may contain a substituent, a benzyl group that may contain a substituent, or an allyl group. However, in the above (), X is an oxygen atom or a sulfur atom, R is an alkyl group having at least 3 carbon atoms, and R ₁ is a hydrogen atom or a methyl group. Croconic metine pigment However, in the above formulas () and (), R ₁ and R ₂ represent a substituted or unsubstituted alkyl group, a cyclic alkyl group, an allyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group. Z ₁ and Z ₂ represent a group of nonmetallic atoms necessary to complete a substituted or unsubstituted heterocycle. m and n are 0 or 1. M represents a cation and X represents an anion. However, in the above formula (), R ₁ and R ₂ represent an alkyl group. Further, R ₁ and R ₂ may form a ring together with the nitrogen atom. R ₃ , R ₄ , R ₅ and R ₆ represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or a hydroxy group. Furthermore, R ₁ and R ₂ may be combined to form a benzene ring, and R ₃
And R ₄ may be combined with R ₅ and R ₆ to form a benzene ring. merocyanine pigment However, in the above formula (),

【ceremony,

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【formula】

【formula】

【Formula】na Which ring does it represent?

【ceremony,

【formula】

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It represents a ring such as [Formula], and n represents 1 or 2. In addition, the solvent used in the present invention is preferably a polar solvent for the above-mentioned polar organic dye. Examples include solvents that have polarity as a whole molecule even if the molecule is not polar. These solvents used have boiling points in the range of 80 to 160°C. boiling point lower than 80℃,
Low-boiling molecules with high vapor pressure evaporate before being incorporated into organic dyes, making them difficult to solvate, and high-boiling molecules with large molecular weights, with boiling points higher than 160°C, have difficulty approaching organic dyes due to steric hindrance, etc. , it becomes difficult to solvate. Specifically, alcohols such as propanol, isopropyl alcohol, butanol, amyl alcohol, isoamyl alcohol, hexyl alcohol, cyclohexanol, and furfuryl alcohol; ethers such as methyl cellosolve, cellosolve, diethyl cellosolve, butyl cellosolve, acetal, and dioxane; Methyl isobutyl ketone, diacetone alcohol, cyclohexanone,
Ketones such as acetylacetone, esters such as butyl formate, amyl formate, propyl acetate, butyl acetate, amyl acetate, methyl cellosolve acetate, cellosolve acetate, nitrohydrocarbons such as nitromethane, nitroethane, nitropropane, nitrobutanol, bromoform, Chlorinated solvents such as methylene iodide, ethylene chloride, ethylidene chloride, trichlorethylene, propylene chloride, dichlorobutane, hexachloropropylene, amyl chloride, chlorobenzene, trichlorobenzene, chlorotoluene, and other paraldehyde, crotonaldehyde, furfural, acetonitrile, dimethyl Formamide, acetol, sulfolane, 2-
Solvents such as mercaptoethyl alcohol and N-methylpyrrolidone are also used. The amount of the above solvent relative to the solvated organic dye is
0.01 to 5% by weight is preferred. If the amount is less than this, the improvement in thermal properties will not be significant, and if it is more than this, the optical properties of the dye will be affected, and there will be stability problems such as solvent coming out when left at high temperatures. In this case, even if the recording layer contains not only a single organic dye but also additives, polymers, etc., the same effect of the solvent solvated by the organic dye can be obtained. In addition, even if a protective layer or a reflective layer is provided on the recording layer, an undercoat layer is provided between the recording layer and the base material that supports the recording layer, or an optical information having an air sandwich structure is provided. Even in recording media, the above-mentioned solvation effect can be obtained in the same way, although there are differences in degree due to differences in thermal conductivity. Solvated solvent can be measured by peeling off the recording layer and determining the loss on drying, by infrared spectroscopy to determine the peak intensity ratio, or by dissolving it in another solvent and determining it qualitatively by gas chromatography. It is possible to quantify. It is preferable to use a spin coating method to form the recording layer on the base material. In this case, the thickness of the coated layer after drying can be any conventionally used thickness. The solvent used for spin coating is a solvent that solvates the organic dye, but it is preferable to select a solvent that has an evaporation rate that is compatible with the drying properties of the coating film. However, it is sufficient if a solvent with an appropriate evaporation rate is mixed and the organic dye in the coating film is solvated as a result. The organic dye concentration of the coating liquid when spin coating is 1 to 10.
% is preferred. The base material supporting the recording layer used in the present invention includes glass, epoxy resin, methacrylic resin,
Polycarbonate resin, polyester resin, polyvinyl chloride resin, etc. can be used. In the present invention, a recording layer is formed by applying an organic dye solution to the above substrate by a spin coating method, and this recording layer becomes solvated by removing much of the solvent by this spin coating method. It is formed by leaving the organic dye on the base material, and there is no particular drying step. Information is then recorded on this recording layer by irradiation with laser light. In particular, the reason why a drying step is not provided is that the solvent solvated in the organic dye is not removed by evaporation. From this point of view, it is preferable to perform recording in a state in which the initial solvation of the organic dye is maintained, such as by performing recording on the recording layer immediately after its formation. Recording is performed on a recording layer formed without a particular drying step in this way. In the conventional method other than the present invention, an organic dye solution is applied to a base material by a spin coating method, and then a heating drying step is provided. This is a significant difference from forming a recording layer and recording on it. Effect When the organic dye in the recording layer is solvated, the melting point and decomposition start temperature of the organic dye decrease, and oxidative decomposition and weight loss continue to occur rapidly. Generally, during optical recording, the temperature from around the melting point to the time when oxidative decomposition occurs is important, and when oxidative decomposition reactions proceed in a chain, holes are formed in the same reaction mode from small pits to large pits. It is thought that since this becomes the recording signal, jitter and errors can be reduced. Example Next, an example will be described. Example 1 1,1'diethyl 3,3,3',3'-tetramethylindotricarbocyanine perchlorate (product number NK 2885 manufactured by Japan Photosensitive Color Research Institute) 0.08 g was dissolved in a mixed solvent of 2 ml of ethanol and 0.5 ml of nitromethane and spin coated onto an acrylic substrate to form a recording layer. Immediately after forming this recording layer, a 1MHz signal was recorded using a laser with a wavelength of 830nm at a linear velocity of 5.6m/sec, and the waveform of the reproduced signal was good, the jitter was 20ns, and the error rate was: 2.3×
It was 10 ^-5 . Comparative Example 1 In Example 1, after the recording layer was formed, it was degassed at a temperature of up to 60°C and held under a reduced pressure of 2 mTorr for 24 hours, and then recording was performed in the same manner as in Example 1. The reproduced signal was Distortion appears in the waveform, and jitter
The error rate was 1.0×10 ^-4 . The cyanine dye used in Example 1 above was dissolved in nitromethane in a test tube, and the heating loss (mg) was determined using a thermobalance for a sample obtained by drying. This was recorded on the TG curve and the temperature difference with respect to the standard sample. (due to heat generation and heat absorption) was measured with a thermocouple and expressed as heat flow (μV)
The DTA curve is shown in Figure 1. Also, for comparison,
The TG curve and DTA curve of only the above cyanine dye were obtained in the same manner as above, and the results are shown in FIG. From these figures, it can be seen that in the part where the TG curve changes rapidly, the temperature of the exothermic part of the peak of the DTA curve shifts to the lower temperature side, and the weight loss increases, indicating that the oxidative decomposition reaction shifts to the lower temperature side. death,
It can be seen that this is consistent with the recording and reproduction results of the recording layers of Example 1 and Comparative Example 1. In addition, the same cyanine dye as in the case of Fig. 1 was dissolved in methyl isobutyl ketone in a test tube, and the TG curve and DTA curve were obtained for a sample obtained by drying it as in the case of Fig. 1, and the curves are shown in Fig. 3. . The thermal characteristics shown in Figure 3 are particularly effective for high-speed recording and pitch-edge recording, which is sensitive to jitter, because the oxidative decomposition reaction shifts to the lower temperature side and there is more weight loss, as in the case of Figure 1. , is considered preferable. Example 2 1,1'di-3-sulfopropyl3,3,3',
3'tetramethyl 4,5,4',5'dibenzo-10-diphenylamino 9,11-ethylene indodicarbocyanine sodium salt 0.1 g was dissolved in 2 ml of methyl isobutyl ketone and spin coated onto a glass substrate to form a recording layer. Immediately after forming this recording layer, an EFM signal was recorded using a laser with a wavelength of 780 nm at a linear velocity of 1.2 m/sec. The eye pattern of the reproduced signal was good, the jitter was 22 ns, and the number of CI errors was teeth
It was hot at 15cps. Comparative Example 2 The recording layer on the glass plate obtained in Example 2 was treated in the same manner as in Comparative Example 1, recorded in the same manner as in Example 2, and then reproduced. The jitter was 32 ns and the number of CI errors was 300 cps. It was hot. Effects of the Invention As explained above, according to the present invention, the boiling point is 80
A recording layer containing an organic dye solvated with a solvent at ~160°C is formed by spin coating without any drying process, and the initial solvation of the organic dye is retained in this recording layer. Since the information is recorded by irradiation with laser light,
In addition to increasing the solvation efficiency, it is also possible to record in its optimal state, which makes it possible to improve the thermal properties during recording using a simple method, which improves the pit shape and improves the recording performance during playback. Jitter and errors can be improved.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the TG curve and DTA curve of the solvated organic dye used in an embodiment of the optical information recording medium of the present invention, and FIG. 2 is the TG curve of the dried state. A graph showing a DTA curve. FIG. 3 is a graph showing a TG curve and a DTA curve in a state in which the solvent used in another example was solvated.

Claims (1)

[Claims] 1. A recording layer is formed on the surface of a substrate by spin coating using a dye solution containing an organic dye and a solvent that solvates the organic dye, and information is recorded on the recording layer by irradiation with laser light. In the method for recording an optical information recording medium, the information is transferred to the recording layer formed by controlling the boiling point of the solvent to 80°C to 160°C without providing any drying process other than the spin coating method. A method for recording an optical information recording medium, characterized in that recording is performed in a state in which the initial solvation of the organic dye is maintained.