JPH06199045A - Photo recording medium - Google Patents

Abstract

PURPOSE:To perform high density recording with sufficient sensitivity and reflectance for laser of a short wavelength by a method wherein a recording film is formed of a substance containing cyanin represented by a specific general formula, in an optical recording medium produced such that the recording film is formed on a light transmissive substrate. CONSTITUTION:In an optical recording medium for a write once, read many optical disc, a recording film formed of the light transmissive substrate is formed of a substance containing cyanin represented by a general formula as described at the right. In the formula, R1 and R2 each represents any one of an alkyl group, an aryl group, and an alkoxyl group, and W1 and W2 each represents a substituent an alkyl groups, an alkoxyl group, an aryl group, an alkoxycarbonyl group, a sulfonyl alkyl group, and a cyano group. Further, Y represents a substituent, such as a halogen atom, a hydrogen atom, or an alkyl group, and X(-) represents gegen ion, such as I(-), Br(-), C104(-), BF4(-), PF6(-), SbF6(-), CH3SO4(-), CH3-CH4-SO3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly to a so-called writable write-once type optical recording medium having a recording film containing an organic dye.

[0002]

2. Description of the Related Art Optical recording media have come into widespread use because they generally have a large storage capacity and have excellent characteristics such as writing and reading in a non-contact manner.

As an example of such an optical recording medium, for example, a so-called writable write once type (WORM: Write Once) is used.
There is a read multiple) optical disc that collects a laser beam on a very small area of the recording film, converts it into heat energy, and changes the properties of the recording film (pit formation) for recording. Playback is performed according to the difference in the amount of reflected light.

It is generally well known that an organic dye is used in the recording film of this write-once type optical recording medium, and in order to smoothly change the properties of this recording film, the medium is formed on a substrate. It is general that a so-called air sandwich structure is prepared in which two recording films are provided on the recording medium and the recording films are arranged to face each other.

Here, as the organic dye contained in the recording film of such a medium, for example, the following general formulas;

[0006]

[Chemical 7] [In the formula (5), R ₁ and R ₂ each represent an alkyl group, an aryl group or an alkoxy group, Y represents a halogen atom, a hydrogen atom or a substituent such as an alkyl group, and W ₁ and W ₂ represents a halogen atom, a hydrogen atom or a substituent such as an alkyl group, an alkoxy group, an aryl group, an alkoxysulfonyl group, a sulfonylalkyl group and a cyano group, and Z ₁ and Z ₂ are a sulfur atom, an oxygen atom and a selenium atom, respectively. Or represents a substituent such as ethylene,

[0007]

[Chemical 8] Represents a counter ion. Further, m and n each represent 0 or a positive integer. ] The cyanine dye represented by the indoline type cyanine dye represented by

[0008]

However, in recent years,
Shorten the wavelength of the semiconductor laser from the current one (680n
m), attempts have been made to carry out high-density recording, and there is a problem that the cyanine dyes conventionally used in write-once type optical recording media cannot provide sufficient sensitivity.

That is, the cyanine dye conventionally used in the write-once type optical recording medium has sufficient reflectance and maximum absorption in the vicinity of the wavelength (780 to 830 nm) of the current high-power laser when it is thinned. , Therefore, during stable reproduction and recording, it has the advantage that the semiconductor laser beam focused on the recording film is efficiently absorbed and converted into heat energy, while at the wavelength of the laser used for high-density recording. This is because it does not have sufficient reflectance and maximum absorption wavelength in the vicinity of a certain 680 nm.

Therefore, as a result of extensive studies by the present inventors, a specific cyanine dye having an absorption at 570 to 670 nm in a solution was formed into a thin film, which was sufficiently close to 680 nm, which is the wavelength of a laser used for high density recording. It has been found that a recording film of an optical recording medium which has reflectance and maximum absorption and is suitable for high density recording can be formed.

The present invention has been made based on such findings, and an object of the present invention is to provide an optical recording medium suitable for high density recording using a semiconductor laser of short wavelength.

[0012]

The constitution of the present invention for solving the above-mentioned problems is an optical recording medium having a light-transmissive substrate and a recording film formed on the substrate, wherein the recording film is The following general formula (1);

[0013]

[Chemical 9] [In the formula (1), R ₁ and R ₂ each represent an alkyl group, an aryl group or an alkoxy group, and W ₁ and W ₂ are a halogen atom, a hydrogen atom or an alkyl group, an alkoxy group or an aryl group, respectively. Base,
Represents a substituent such as an alkoxycarbonyl group, a sulfonylalkyl group and a cyano group, Y represents a substituent such as a halogen atom, a hydrogen atom or an alkyl group,

[0014]

[Chemical 10] Represents a counter ion such as. Also, n is 0, 1 or 2. ] An optical recording medium characterized by containing a cyanine represented by: an optical recording medium having a light-transmissive substrate and a recording film formed on the substrate,
The recording film has the following general formula (2);

[0015]

[Chemical 11] [However, in the formula (2), R ₁ and R ₂ each represent an alkyl group, an aryl group or an alkoxy group,

[0016]

[Chemical 12] Represents a counter ion such as. Also, n is 0, 1 or 2. ] An optical recording medium characterized by containing a cyanine represented by: an optical recording medium having a light-transmissive substrate and a recording film formed on the substrate,
The recording film has the following general formula (3);

[0017]

[Chemical 13] [In the formula (3), R ₁ and R ₂ each represent an alkyl group, an aryl group or an alkoxy group, and W ₁ and W ₂ are a halogen atom, a hydrogen atom or an alkyl group, an alkoxy group or an aryl group, respectively. Base,
It represents a substituent such as an alkoxycarbonyl group, a sulfonylalkyl group and a cyano group. Also, n is 0, 1 or 2. ] An optical recording medium characterized by containing a cyanine represented by the following: in an optical recording medium having an optically transparent substrate and a recording film formed on the substrate, General formula (4);

[0018]

[Chemical 14] [However, in the formula (4), R ₁ and R ₂ each represent an alkyl group, an aryl group or an alkoxy group. ] It is an optical recording medium characterized by containing the cyanine represented by these.

[0019]

EXAMPLES Next, examples of the present invention will be shown to more specifically describe the optical recording medium of the present invention.

FIG. 1 is a partial sectional view showing an example of the optical recording medium of the present invention. As shown in FIG. 1, this optical recording medium is a so-called air sandwich in which two recording film-attached substrates each having a recording film 2 formed on a light-transmissive substrate 1 are arranged so that the recording films 2 face each other. It is considered as a structure. here,
In FIG. 1, 5 is a spacer.

The light-transmissive substrate 1 has a disk shape, and on one side of the substrate 1, usually prepits or pregrooves for tracking are formed in a concentric or spiral shape. The substrate 1 having such pre-pits or pre-grooves is preferably a so-called integrally formed injection-molded resin substrate from the viewpoint of improving productivity. For example, a polycarbonate resin (PC), poly Methyl methacrylate resin (PM
MA), amorphous polyolefin resin (APO), or the like. Further, not only the injection-molded resin substrate integrally formed, but also so-called 2P (photo-poly)
(mer) method may be used. The thickness of such a substrate 1 is about 1.0 to 1.5 mm.

Recording film 2 formed on this substrate 1
Contains cyanine represented by any of the following general formulas (1) to (4).

[0023]

[Chemical 15] [In the formula (1), R ₁ and R ₂ each represent an alkyl group, an aryl group or an alkoxy group, and W ₁ and W ₂ are a halogen atom, a hydrogen atom or an alkyl group, an alkoxy group or an aryl group, respectively. Base,
Represents a substituent such as an alkoxycarbonyl group, a sulfonylalkyl group and a cyano group, Y represents a substituent such as a halogen atom, a hydrogen atom or an alkyl group,

[0024]

[Chemical 16] Represents a counter ion such as. Also, n is 0, 1 or 2. ]

[0025]

[Chemical 17] [However, in the formula (2), R ₁ and R ₂ each represent an alkyl group, an aryl group or an alkoxy group,

[0026]

[Chemical 18] Represents a counter ion such as. Also, n is 0, 1 or 2. ]

[0027]

[Chemical 19] [In the formula (3), R ₁ and R ₂ each represent an alkyl group, an aryl group or an alkoxy group, and W ₁ and W ₂ are a halogen atom, a hydrogen atom or an alkyl group, an alkoxy group or an aryl group, respectively. Base,
It represents a substituent such as an alkoxycarbonyl group, a sulfonylalkyl group and a cyano group. Also, n is 0, 1 or 2. ]

[0028]

[Chemical 20] [However, in the formula (4), R ₁ and R ₂ each represent an alkyl group, an aryl group or an alkoxy group. Each of these cyanines has a maximum absorption wavelength near 680 nm when formed into a thin film and has a wavelength of 6
It has sufficient sensitivity and reflectance for light near 80 nm and exhibits good storage stability.

More specific examples of such cyanine include the compounds shown below.

[0030]

[Chemical 21]

[0031]

[Chemical formula 22]

[0032]

[Chemical formula 23]

[0033]

[Chemical formula 24]

[0034]

[Chemical 25]

[0035]

[Chemical formula 26]

[0036]

[Chemical 27]

[0037]

[Chemical 28]

[0038]

[Chemical 29]

[0039]

[Chemical 30]

[0040]

[Chemical 31]

[0041]

[Chemical 32]

[0042]

[Chemical 33]

[0043]

[Chemical 34]

[0044]

[Chemical 35]

[0045]

[Chemical 36]

[0046]

[Chemical 37]

[0047]

[Chemical 38]

[0048]

[Chemical Formula 39]

[0049]

[Chemical 40]

[0050]

[Chemical 41]

[0051]

[Chemical 42]

[0052]

[Chemical 43]

[0053]

[Chemical 44]

[0054]

[Chemical formula 45]

[0055]

[Chemical formula 46]

[0056]

[Chemical 47]

[0057]

[Chemical 48]

[0058]

[Chemical 49]

[0059]

[Chemical 50]

[0060]

[Chemical 51]

[0061]

[Chemical 52]

[0062]

[Chemical 53] For example, these cyanine dyes are usually used alone, but may be used in combination of two or more if necessary.

The recording film 2 may contain a quencher together with such a cyanine dye. This quencher is used to improve the light stability of the recording film 2 containing a cyanine dye as a main component, and particularly to prevent discoloration (reproduction deterioration) due to reading light.

Specific examples of the quencher preferably used with the above cyanine dye include those represented by the following structural formulas.

[0065]

[Chemical 54]

[0066]

[Chemical 55]

[0067]

[Chemical 56]

[0068]

[Chemical 57] The recording film 2 containing the above-mentioned cyanine as a main component is coated on the substrate 1 by a conventional means such as spin coating.

The thickness of the recording film 2 is about 10 to 1000 nm, preferably about 100 to 700 nm. If this value is less than 10 nm, the recording sensitivity and reflectance may be insufficient, and ideal recording may not be possible. on the other hand,
If this value exceeds 700 nm, the recording sensitivity may be insufficient.

As the solvent used for coating, various known solvents can be used, for example, diacetone alcohol, ethyl cellosolve, methyl cellosolve, isophorone, methanol, tetrafluoropropanol, cyclohexanone, 1,2-dichloroethane and the like. Can be mentioned.

As shown in FIG. 1, this optical recording medium is a so-called air sandwich in which two recording film-attached substrates each having a recording film 2 formed on the substrate 1 are prepared and the recording films 2 are arranged so as to face each other. The structure may be used, or, for example, as shown in FIG. 2, the structure may be such that the recording film 2, the light reflection film 3, and the protective film 4 are provided on the substrate 1 in this order from the substrate 1 side.

The light reflecting film 3 which may be provided on the recording film 2 is made of a metal such as Au, Al, Ag and Cu, which is formed by vacuum vapor deposition, sputtering, ion plating or the like. . The thickness of such a light reflecting film 3 is about 0.02 to 2.0 μm.

The protective film 4 which may be provided on the light reflecting film 3 is generally formed by applying an ultraviolet curable resin by a spin coating method and then irradiating it with ultraviolet rays to cure the coating film. It is a thing. In addition, an epoxy resin, an acrylic resin, a silicone resin, a urethane resin or the like is also used as a material for forming the protective film 4. The thickness of the protective film 4 is
Usually, it is about 0.01 to 100 μm.

A top coat film made of an organic material for adjusting the reflectance may be provided on the surface of the substrate 1 in the direction opposite to the direction in which the recording film 2 is formed. An intermediate layer for protecting the substrate 1 from a solvent may be provided between the film 2 and the film 2.

The wavelength of laser light suitably applied to this optical recording medium is about 680 nm. The optical recording medium of the present invention has sufficient sensitivity and reflectance with respect to a laser having a short wavelength as described above (the wavelength of a conventional semiconductor laser is 780 to 830 nm), thereby achieving high density recording. . (Experimental example) Hereinafter, the present invention will be described in more detail with reference to experimental examples. Preparation of Samples Each of the combinations of dyes and quenchers shown in Table 1 below was dissolved in a solvent of diacetone alcohol, and applied on a polycarbonate (PC) substrate 1 having a diameter of 130 mm to a thickness of about 500 nm by spin coating. The recording film 2 was formed.

Then, an optical recording medium having an air sandwich structure was prepared by disposing two recording film-attached substrates each having the recording film 2 provided on the substrate 1 so that the recording films 2 face each other. In this way, 13 types of optical recording media were prepared and used as samples 1 to 13.

[0077]

[Table 1] Experimental Example 1 Sample (1) to Sample (4) and Sample (5) to Sample (7)
For each of the above, an environment resistance test was performed under the condition of 70 ° C.-90% RH, and the change in absorbance of the dye was measured.

The results are shown in FIG. As is clear from FIG. 3, samples (1) to (4) provided with a recording film containing the cyanine represented by any one of the formulas (1) to (4).
Is smaller in change in absorbance than the samples (5) to (7) including the recording film containing a dye other than the cyanine represented by any of the above formulas (1) to (4), and is environmentally resistant. It was confirmed to be excellent. Experimental Example 2 For each of Sample 8 and Sample 9, ISO130
Based on the mmWO optical disk sampled servo format, four types of reproduction signal outputs by the returning light were measured.
The results are shown in FIGS. Here, FIG. 4 shows the reproduction signal output at the wobble pit, and FIG. 5 shows the reproduction signal output at the synchronization pit. 6 and 7 show the reproduction signal output of 1T signal and 3T signal after the information is actually recorded.

From these results, the above equations (1) to (4)
It was confirmed that Sample 8 and Sample 9 (both of the present invention) provided with the recording film containing cyanine represented by any one of (1) to (4) were small in deterioration of reproduction signal output. Experimental Example 3 With respect to each of Sample 10 and Sample 11, four types of reproduced signal outputs by returning light were measured in the same manner as in Experimental Example 2. The results are shown in FIGS. Here, FIG. 8 shows the reproduction signal output at the wobble pit, and FIG. 9 shows the reproduction signal output at the synchronization pit. Also, FIG. 10 and FIG.
1 is a 1T signal after actually recording information, and 3T
The reproduced signal output of the signal is shown.

From these results, the above equations (1) to (4)
It was confirmed that the samples 10 and 11 (both of the present invention) provided with the recording film containing cyanine represented by any of the above (invention products) had a small deterioration in reproduction signal output. Experimental Example 4 With respect to the sample 12, four types of reproduced signal outputs by returning light were measured in the same manner as in Experimental Example 2. The results are shown in FIG.
It shows in FIG. Here, FIGS. 12 to 15 show the reproduction signal output in the wobble pit, the reproduction signal output in the synchronization pit, and the 1T signal and the 3T signal reproduction signal output for the initial recording portion (the portion where the information is actually recorded), respectively. Shown in FIG.
17 and FIG. 17 respectively show reproduction signal outputs of 1T signal and 3T signal for the re-recording portion (the portion where information is recorded again).

From these results, the above equations (1) to (4)
It was confirmed that Sample 12 (the product of the present invention) including the recording film containing cyanine represented by any one of the above 1) had little deterioration in the reproduction signal output in both the initial recording portion and the rerecording portion. Experimental Example 5 With respect to the sample 13, four types of reproduced signal outputs by returning light were measured in the same manner as in Experimental Example 2. The results are shown in FIG.
It shows in FIG. Here, FIGS. 18 to 21 show the reproduction signal output at the wobble pit, the reproduction signal output at the synchronization pit, and the 1T signal and the 3T signal reproduction signal output for the initial recording portion (the portion where the information is actually recorded), respectively. Shown in FIG.
23 and FIG. 23 show 1T signal and 3T signal reproduction signal outputs for the re-recording portion (the portion where information is recorded again).

From these results, the above equations (1) to (4)
It was confirmed that the sample 13 (the product of the present invention) including the recording film containing cyanine represented by any one of the above 1) had little deterioration in the reproduction signal output in both the initial recording portion and the rerecording portion. Experimental Example 6 For each of Sample 8 to Sample 13, 70 ° C.-90%
The transition of the byte error rate was measured under the condition of RH.

The results are shown in Table 2. In Table 2, values in parentheses are rerecorded values. From this result, the equations (1) to
Samples 8 to 13 (each of which is a product of the present invention) having the recording film containing cyanine represented by any of (4) have stable characteristics that the bit error rate is extremely small. Was confirmed.

[0084]

[Table 2]

[0085]

The optical recording medium of the present invention has a structure in which a specific recording film containing a cyanine dye having a specific structure is provided on a substrate. Therefore, according to the present invention, a laser of short wavelength (about 680 nm) is used. On the other hand, there is provided an optical recording medium having sufficient sensitivity and reflectance, excellent environmental resistance, stable reproduction characteristics with little deterioration in reproduction, and suitable for high density recording.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an optical recording medium of the present invention.

FIG. 2 is a partially enlarged sectional view showing another example of the optical recording medium of the present invention.

FIG. 3 is a graph showing a change in absorbance of a dye due to an environment resistance test.

FIG. 4 is a graph showing the transition of the reproduction output level at wobble pits for the optical recording medium of the present invention.

FIG. 5 is a graph showing a transition of a reproduction output level at a sync pit in the optical recording medium of the present invention.

FIG. 6 is a graph showing a transition of a reproduction output level of a 1T signal in the optical recording medium of the present invention.

FIG. 7 is a graph showing a transition of a reproduction output level of a 3T signal in the optical recording medium of the present invention.

FIG. 8 is a graph showing the transition of the reproduction output level at wobble pits for the optical recording medium of the present invention.

FIG. 9 is a graph showing the transition of the reproduction output level at the sync pit in the optical recording medium of the present invention.

FIG. 10 is a graph showing the transition of the reproduction output level of 1T signal in the optical recording medium of the present invention.

FIG. 11 is a graph showing the transition of reproduction output level of 3T signal in the optical recording medium of the present invention.

FIG. 12 is a graph showing the transition of the reproduction output level at wobble pits for the optical recording medium of the present invention.

FIG. 13 is a graph showing the transition of the reproduction output level at the sync pit for the optical recording medium of the present invention.

FIG. 14 is a graph showing the transition of the reproduction output level of the 1T signal in the initial recording section of the optical recording medium of the present invention.

FIG. 15 is a graph showing the transition of the reproduction output level of the 3T signal in the initial recording section of the optical recording medium of the present invention.

FIG. 16 shows 1 in the re-recording section for the optical recording medium of the present invention.
7 is a graph showing a transition of a reproduction output level of a T signal.

FIG. 17 is a graph of the optical recording medium of the present invention in the re-recording part
7 is a graph showing a transition of a reproduction output level of a T signal.

FIG. 18 is a graph showing the transition of the reproduction output level at wobble pits for the optical recording medium of the present invention.

FIG. 19 is a graph showing the transition of the reproduction output level at the sync pit for the optical recording medium of the present invention.

FIG. 20 is a graph showing the transition of the reproduction output level of the 1T signal in the initial recording section of the optical recording medium of the present invention.

FIG. 21 is a graph showing the transition of the reproduction output level of the 3T signal in the initial recording section of the optical recording medium of the present invention.

FIG. 22 shows 1 in the re-recording section for the optical recording medium of the present invention.
7 is a graph showing a transition of a reproduction output level of a T signal.

FIG. 23 shows the optical recording medium of the present invention in the re-recording section.
7 is a graph showing a transition of a reproduction output level of a T signal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Recording film 3 ... Light reflection film 4 ... Protective film 5 ... Spacer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fumio Matsui 6-1, 1-1 Fujimi, Tsurugashima City, Saitama Pioneer Corporation Research Institute (72) Inventor Yoshie Yokoyama 1-3-2 Shimoishii, Okayama City, Okayama Prefecture No. 2 Incorporated Japan Sensitivity Research Institute (72) Inventor Akira Kampo 1 2-3 Shimoishii, Okayama-shi, Okayama Incorporated Japan Sensitivity Research Lab. (72) Inventor, Yoshiki Okazaki 1-chome Shimoishii, Okayama-shi, Okayama No. 2 and No. 3 Japan Stock Photosensitivity Research Institute

Claims (4)

[Claims] 1. An optical recording medium having a light transmissive substrate and a recording film formed on the substrate, wherein the recording film has the following general formula (1); [In the formula (1), R ₁ and R ₂ each represent an alkyl group, an aryl group or an alkoxy group, and W ₁ and W ₂ are a halogen atom, a hydrogen atom or an alkyl group, an alkoxy group or an aryl group, respectively. Base,
Represents a substituent such as an alkoxycarbonyl group, a sulfonylalkyl group and a cyano group, Y represents a substituent such as a halogen atom, a hydrogen atom or an alkyl group, and Represents a counter ion such as. Also, n is 0, 1 or 2. ] The optical recording medium containing the cyanine represented by these. 2. An optical recording medium having a light-transmissive substrate and a recording film formed on the substrate, wherein the recording film has the following general formula (2); [In the formula (2), R ₁ and R ₂ each represent an alkyl group, an aryl group or an alkoxy group; Represents a counter ion such as. Also, n is 0, 1 or 2. ] The optical recording medium containing the cyanine represented by these. 3. An optical recording medium having a light-transmissive substrate and a recording film formed on the substrate, wherein the recording film has the following general formula (3); [In the formula (3), R ₁ and R ₂ each represent an alkyl group, an aryl group or an alkoxy group, and W ₁ and W ₂ are a halogen atom, a hydrogen atom or an alkyl group, an alkoxy group or an aryl group, respectively. Base,
It represents a substituent such as an alkoxycarbonyl group, a sulfonylalkyl group and a cyano group. Also, n is 0, 1 or 2. ] The optical recording medium containing the cyanine represented by these. 4. An optical recording medium having a light-transmissive substrate and a recording film formed on the substrate, wherein the recording film has the following general formula (4); [However, in the formula (4), R ₁ and R ₂ each represent an alkyl group, an aryl group or an alkoxy group. ] The optical recording medium containing the cyanine represented by these.