JP2011183579A - Pigment for optical information recording medium and optical information recording medium using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide pigment, for an optical information recording medium, which can make an In-Groove recording, using short wavelength laser beams (405 nm) like an organic BD-R, and also, can obtain successful recording characteristics with high sensitivity, as well as an optical information recording medium. <P>SOLUTION: This optical information recording medium uses azo-metallic complex pigment of a specific structure shown in the formula as a recording layer material. In the formula, Y<SP>+</SP>is a tertiary amine or a quarternary ammonium; R<SB>2</SB>is an electron attractive substituting group; R<SB>3</SB>is an alkyl ether, an aromatic(aryl) ether or an arylamino group. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dye for optical information recording media, and more specifically, to a dye for optical information recording media for recording with a laser beam (blue laser light, blue violet laser light) having a wavelength of 360 to 450 nm by a semiconductor laser. The present invention relates to an optical information recording medium.

  A write-once optical recording medium using an organic dye as a recording material performs recording / reproduction using a CD-R having a recording capacity of 650 MB or 700 MB for recording / reproducing using a laser beam having a wavelength of 780 nm, or a laser beam having a wavelength of 650 nm. Single-layer DVD-R / + R with a recording capacity of 4.7 GB is already widely used. These are high-to-low type recordings in which information is recorded as a signal by having a high reflectivity when not recorded and a low reflectivity after recording.

  As a further large-capacity medium, in 2006, a high definition (HD) DVD-R with a recording capacity of 15 GB in a single layer was recorded and reproduced with a laser having a wavelength of 405 nm. In the HD DVD-R, the recording polarity is Low to High, where the reflectance when not recorded is low and the reflectance becomes high after recording. Blu-ray Disc-R (hereinafter referred to as “Organic BD-R”) using an organic dye as a recording layer, which is currently being developed, performs recording / reproduction with a laser having a wavelength of 405 nm and has a recording capacity of a single layer. Is a 25 GB recordable optical recording medium. The organic BD-R recording polarity is Low to High, similar to HD DVD-R.

There has been proposed a new organic dye suitable for an optical information recording medium capable of recording / reproducing high-density optical information by Low to High recording.
For example, in Patent Document 1, a low-to-high type 405 nm laser with an HD DVD-R structure was used by using an organic dye whose cation portion is a monomethine cyanine dye and whose anion portion is an azo metal complex. It shows that recording and playback can be performed. However, the evaluation results of the characteristics of the disc as the organic BD-R are not described. Further, in this patent, the dye composed of an anion portion and a cation portion is an atomic group in which the cation portion in the organic dye exhibits a substantial light absorption ability for a short wavelength laser beam such as a blue laser beam. As it works.
Further, in Patent Document 2 and Patent Document 3, a specific azo metal complex is said to be suitable for a medium that performs recording / reproduction using a 405 nm laser beam for Low to High recording. Is not listed.

JP-A-2005-297406 JP 2007-196661 A JP 2007-45147 A JP 2003-45079 A JP 2003-36562 A

The dyes disclosed in the above patent documents are basically suitable for Low to High recording and can be used for both HD DVD-R and organic BD-R.
However, as a result of intensive studies by the inventors, it has been found that the optimum characteristics of the dye actually differ depending on the difference between the On-Groove recording and the In-Groove recording.

  That is, the HD DVD-R has a dye-containing recording layer and a reflective layer in this order on a first substrate made of a light transmissive material in which guide grooves having a track pitch of 0.40 μm are formed. It is a laminated structure in which a second substrate is provided with or without an adhesive layer, and a so-called dummy disk having a reflective layer formed thereon if necessary, and from one side through the first substrate. Recording / reproduction is performed with a laser beam. The spot diameter of the irradiated laser beam is 0.54 μm.

On the other hand, the organic BD-R has a reflective layer and a dye-containing recording layer in this order on a substrate made of a light-transmitting material in which guide grooves having a track pitch of 0.32 μm are formed. It has a laminated structure provided with a transmission layer (cover layer) (Patent Documents 4 and 5), and performs recording and reproduction by laser light irradiated from the light transmission layer (cover layer) side. The spot diameter of the irradiated laser beam is 0.41 μm. Therefore, since the organic BD-R has a smaller spot diameter than the HD DVD-R, the energy density increases with the same recording power. Here, since the organic BD-R has a narrower track pitch than the HD DCD-R, thermal interference with adjacent guide grooves is likely to occur.
When such thermal interference occurs, jitter increases and recording characteristics deteriorate. Therefore, there is a problem that good recording becomes difficult.

  The present invention has been made in view of the above circumstances, and is an optical information recording medium that performs In-Groove recording using a short wavelength laser (405 nm) such as an organic BD-R. In addition, an object of the present invention is to provide a dye for an optical information recording medium capable of obtaining good recording characteristics and an optical information recording medium using the same.

As a result of intensive studies to achieve the above object, the present inventor has found that the above object can be achieved by using an azo metal complex dye having a specific structure as a recording layer material.
The present invention has been completed based on these findings, and is as follows.
[1] An organic dye for a recording layer of a write-once optical information recording medium that performs recording and reproduction with a laser beam having a wavelength of 360 to 450 nm, and is represented by the following general formula: Pigment.
[In the formula, Y ⁺ represents the following formula:
(In the formula, at least three of R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ are the same or different alkyl groups, and the other one is the same or different alkyl group or hydrogen atom as the other). Tertiary amine or quaternary ammonium, R ₂ represents an electron-withdrawing substituent, and R ₃ represents an alkyl ether or aryl ether, or an arylamino group. ]
[2] A substrate having a spiral guide groove on one surface, a reflective layer formed on one surface of the substrate, a recording layer formed on the reflective layer, and formed on the recording layer In a write-once type optical information recording medium that has at least a protective layer and a light transmission layer formed on the protective layer, and performs recording and reproduction with a laser beam having a wavelength of 360 to 450 nm,
An optical information recording medium, wherein the organic dye used in the recording layer is represented by the following general formula:
[In the formula, Y ⁺ represents the following formula:
(In the formula, at least three of R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ are the same or different alkyl groups, and the other one is the same or different alkyl group or hydrogen atom as the other). Tertiary amine or quaternary ammonium, R ₂ represents an electron-withdrawing substituent, and R ₃ represents an alkyl ether or aryl ether, or an arylamino group. ]

  According to the present invention, in an optical recording medium for recording / reproducing with a short wavelength laser (405 nm) such as an organic BD-R, the sensitivity is high, that is, the laser beam irradiation power in recording is small and the modulation is large. Good recording characteristics with low jitter can be obtained.

Schematic diagram showing the overall configuration of the optical information recording medium of the present invention The figure which shows the absorption spectrum of chemical formula 1 The figure which shows the absorption spectrum of Chemical formula 2 The figure which shows the absorption spectrum of Chemical formula 3 The figure which shows the eye pattern of Example 1 The figure which shows the eye pattern of Example 2 The figure which shows the eye pattern of Example 3 The figure which shows the eye pattern of the comparative example 1

Hereinafter, the optical information recording medium according to the embodiment of the present invention and the dye for the optical information recording medium used for the recording layer will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of an optical information recording medium using a blue laser beam according to an embodiment of the present invention. As shown in FIG. 1, an optical information recording medium 11 of the present invention includes a substrate 2, a light reflecting layer 3 formed on the substrate 2, and a light absorbing layer, that is, an optical recording layer, formed on the light reflecting layer 3. 4, a protective layer 5 formed on the optical recording layer 4, and a cover layer, that is, a light transmission layer 6 formed on the protective layer 5.

  In the optical information recording medium having such a configuration, the laser light 7 is irradiated through the light transmission layer 6, and the irradiated optical recording layer 4 absorbs the laser light and converts the light energy into heat energy. The recording pits are formed, and the contrast due to the light reflectance of the recorded portion and the unrecorded portion is read as an electric signal (degree of modulation).

The optical recording layer 4 is a layer that generates heat, heat absorption, melting, sublimation, deformation or modification by irradiating a laser beam. In the present invention, the optical recording layer 4 is represented by the following general formula. It is comprised by the azo metal complex dye shown.
[Where Y ⁺ is
(In the formula, at least three of R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ are the same or different alkyl groups, and the other one is the same or different alkyl group or hydrogen atom as the other). Tertiary amine or quaternary ammonium, R ₂ represents an electron-withdrawing substituent, and R ₃ represents an alkyl ether, an aromatic (aryl) ether, or an arylamino group. ]

Although it does not specifically limit as an alkyl group represented by R < ₁₁ >, R < ₁₂ >, R <_13> , R < ₁₄ > in a formula, Preferably, a C1-C6 alkyl group is used preferably, Especially, C2-C2 An alkyl group of 4 is preferably used.

In addition, the electron-withdrawing substituent represented by R ₂ in the formula is a substituent having an effect of extracting an electron from the aryl nucleus, and the σp value (substituent constant; Hammett's reaction constant) in the Hammett formula is It is defined as taking a positive value ("Organic Chemistry Handbook", Technical Hall, 3rd Edition, 2nd printing, pages 65-67, or "Chemical Handbook Basic Edition", published by Maruzen, 5th printing, II-364-II-365, etc. reference).
Examples thereof include an alkyl group, a fluorinated alkyl group, a nitro group, a cyano group, a sulfonyl group, an alkoxy group, an amino group, an alkylamine group, and a halogen. Among them, a nitro group and a sulfonyl group are preferably used.

Further, the alkyl ether represented by R ₃ in the formula is not particularly limited, but an alkyl ether having 1 to 6 carbon atoms is preferably used, and a linear alkyl having 2 to 5 carbon atoms is particularly preferable. Ether is used. In addition, the aryl ether represented by R ₃ in the formula is not particularly limited, but phenyl ether is preferably used. Further, the arylamino group represented by R ₃ in the formula is not particularly limited, but a phenylamide group is preferably used.
The method for synthesizing the azo metal complex is not particularly limited. For example, it is described in Yutaka Hosoda “Theoretical Manufacturing Dye Chemistry” (November 25, 1957, published by Gihodo Co., Ltd., pages 595 to 601). Manufactured using the known methods for producing azo metal complexes described.

The optical recording layer 4 has a DC jitter value of a dye solution obtained by dissolving the dye represented by the general formula in an organic solvent such as 2,2,3,3-tetrafluoro-1-propanol (TFP). By coating the surface of the light reflecting layer 3 uniformly by means such as a spin coating method so as to obtain the optical density at the lowest (Optical Density: hereinafter referred to as “OD value”). It is formed.
Here, the OD value indicates the absorbance at the maximum absorption wavelength of the dye. The measurement method is performed by applying a dye solution directly on the substrate 2 of FIG. 1 and measuring the absorbance using light of the maximum absorption wavelength of each dye. The OD value is adjusted according to the film forming conditions (rotation speed, time, etc.). For the OD value at which the DC jitter is lowest, a plurality of sample disks having different OD values by changing the film formation conditions of the optical recording layer 4 are prepared, and a commercially available recording / reproducing apparatus (for example, ODU-1000 manufactured by Pulstec) is used. Recording is performed to determine each DC jitter value, and the result is determined.

Hereinafter, constituent layers other than the optical recording layer 4 in the optical information recording medium 11 of the present invention will be described.
(substrate)
The substrate 2 is a highly transparent material having a refractive index with respect to laser light in the range of, for example, about 1.5 to 1.7, and is formed mainly of a resin excellent in impact resistance, such as a polycarbonate, a glass plate, an acrylic plate. An epoxy board is used.
A spiral guide groove having a pitch of 0.32 μm is formed on the substrate 2. The groove can be used as a ring-shaped groove if the software for guiding the tracking is changed. The groove width W1 of the guide groove is preferably 160 nm to 200 nm, and the groove depth D1 is preferably 32 nm to 45 nm. Here, the groove width W1 is measured by a width at a half depth of the groove depth D1, that is, a half-value width as shown in FIG. A light reflecting film 3 is formed on the guide groove.

(Light reflection layer)
The light reflecting layer 3 is a metal film having a high thermal conductivity and high light reflectivity. For example, gold, silver, copper, aluminum, or an alloy containing these is formed by means such as vapor deposition or sputtering.
The thickness of the light reflecting layer 3 is preferably 40 nm to 65 nm. Since the light reflecting layer 3 is also formed in the guide groove, the size of the guide groove changes by the thickness of the light reflecting layer. The groove width W2 of the groove 3 ′ after forming the light reflecting layer 3 is preferably 150 nm to 190 nm, and the groove depth D2 is preferably 32 nm to 45 nm.

(Protective layer)
The protective layer 5 diffuses the dye contained in the optical recording layer 4 into the cover layer 6 when the cover layer 6 is formed, and penetrates the optical recording layer 4 with a solvent of a cured resin for forming the cover layer 6. This is to prevent the mixing phenomenon. The material constituting the protective layer 5 is silicon oxide, particularly silicon dioxide, oxides such as zinc oxide, cerium oxide and yttrium oxide; sulfides such as zinc sulfide and yttrium sulfide; nitrides such as silicon nitride; silicon carbide A mixture of an oxide and a sulfur compound. The protective layer 5 is formed by a method such as sputtering.

(Light transmission layer)
In the optical information recording medium 11 of the present invention, the laser beam 7 is irradiated through the light transmission layer 6, and the irradiated optical recording layer 4 absorbs the laser beam and converts the light energy into heat energy. 4 is generated, recording pits are formed, and the contrast due to the light reflectance of the recorded portion and the unrecorded portion is read as an electric signal (degree of modulation).
Therefore, the light transmission layer 6 is formed of a material that transmits laser light, for example, a resin such as a polycarbonate resin, an acrylic resin, or a polyolefin resin.
Further, the light transmission layer 6 protects the light reflection layer 3 and the optical recording layer 4 from external impacts, and also functions as a protection layer for preventing the layers 3 and 4 from coming into contact with corrosion factors such as moisture. .
This light transmission layer 6 is formed of a curable resin that is cured by ultraviolet rays or radiation to a thickness of 0.1 mm by spin coating or the like. The light transmittance of the light transmissive layer 6 is 70% or more, preferably 80% or more when measured with a spectrophotometer with light having a wavelength of 405 nm and a thickness of 0.1 mm after the effect.
Since the light transmission layer 6 is relatively soft and easily damaged, a hard coat layer (not shown) made of an acrylic resin or the like may be formed.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1
A spiral guide groove having a pitch of 0.32 μm was formed on a disc-shaped polycarbonate substrate 2 having an outer diameter of 120 mm and a thickness of 1.1 mm shown in FIG. A light reflecting layer 3 made of an Ag alloy is formed by sputtering on the upper surface of the substrate 2 on which the guide groove is formed, and the track corresponding to the guide groove is 45 nm deep on the light reflecting layer 3 when viewed from the substrate side. A width of 160 nm was formed.

On the upper surface on which the light reflecting layer 3 is formed, a dye (dye 1) represented by the following formula showing the absorption spectrum (solution and thin film) of FIG. 2 is added to 2,2,3,3-tetrafluoro-1 -A dye solution dissolved in propanol (TFP) is applied by spin coating, dried at a temperature of 80 ° C. for 10 minutes, and the optical density (OD value) at the maximum absorption wavelength (λmax = 467 nm) is 0.17. Formed.
The OD value refers to the absorbance when the optical recording layer 4 is directly formed without forming the reflective layer 3 on the substrate 2 with the absorbance of the substrate 2 alone as the baseline (OD value is zero). The light reflecting layer 3 made of an Ag alloy was formed on the upper surface of the substrate 2 on the side where the guide groove was formed with the same spin coat rotation pattern. Thereafter, a transparent protective layer 5 made of a ZnS—SiO ₂ material was further sputtered on the upper surface of the optical recording layer 4 to a thickness of 20 nm. Then, a UV curable resin is applied by a spin coating method and cured by UV light irradiation to form a light transmission layer (cover layer) 6 having a thickness of 0.1 mm, and an organic BD-R11 write-once optical information recording medium Samples were obtained.

(Dye 1)

Subsequently, the organic BD-R11 was recorded at a linear velocity of 9.84 m / sec (double speed recording) using a commercially available recording / reproducing apparatus (ODU-1000 manufactured by Pulstec Corp.) having a numerical aperture NA of 0.85 and a laser wavelength of 405 nm. When recording and reproducing characteristics were evaluated, the laser power was 6.4 mW.
Thereafter, when the laser output was set to 0.35 mW and the recorded signal was reproduced using the above-mentioned recorder, the clear eye pattern shown in FIG. 5 was obtained. At this time, the degree of modulation was 42%, and the DC jitter was 9.8%.
Table 1 shows the results of measuring the maximum absorption wavelength (λmax), OD value, recording power, modulation degree, and DC jitter.

(Examples 2 to 6)
In Example 1, instead of (Dye 1), (Dye 2), (Dye 3), and the following formulas shown in the following formulas showing the absorption spectra (solution and thin film) shown in FIGS. 3 and 4, respectively. Organic BD-R11 was obtained in the same manner as in Example 1 except that (Dye 4) to (Dye 6) represented by the formula (1) were used.
The results of measuring the maximum absorption wavelength (λmax), OD value, recording power, modulation degree, and DC jitter according to Example 1 are shown in Table 1.

(Dye 2)
(Dye 3)
(Dye 4)
(Dye 5)
(Dye 6)

(Comparative Example 1)
In Example 1, organic BD-R11 was obtained in the same manner except that (Comparative dye 1) represented by the following formula was used instead of the compound of (Dye 1).
(Comparative dye 1)

Table 1 shows the results of measuring the maximum absorption wavelength (λmax), OD value, recording power, modulation degree, and DC jitter according to Example 1.
Subsequently, the organic BD-R11 was recorded at a linear velocity of 9.84 m / sec (double speed recording) using a commercially available recording / reproducing apparatus (ODU-1000 manufactured by Pulstec Corp.) having a numerical aperture NA of 0.85 and a laser wavelength of 405 nm. When recording and reproducing characteristics were evaluated, the laser power was 8.3 mW.
Thereafter, when the laser output was set to 0.35 mW and the recorded signal was reproduced using the above-mentioned recorder, the eye pattern shown in FIG. 8 was obtained, but the waveform was not clear. The degree of modulation at this time was 35%, respectively, and the DC jitter could not be evaluated due to insufficient 2T amplitude.

  The dye for an optical information recording medium of the present invention can be used in an optical recording medium for performing In Groove recording Low to High type recording with a blue laser.

2: Substrate 3: Light reflection layer 4: Optical recording layer (light absorption layer)
5: Protective layer 6: Light transmission layer (cover layer)
7: Laser light (recording, reproduction)
11: Write-once optical disc of the present invention (organic BD-R)

Claims (2)

A dye for an optical information recording medium, which is an organic dye for a recording layer of a write-once type optical information recording medium that performs recording and reproduction with a laser beam having a wavelength of 360 to 450 nm, and is represented by the following general formula.
[In the formula, Y ⁺ represents the following formula:
(In the formula, at least three of R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ are the same or different alkyl groups, and the other one is the same or different alkyl group or hydrogen atom as the other). Tertiary amine or quaternary ammonium, R ₂ represents an electron-withdrawing substituent, and R ₃ represents an alkyl ether, aryl ether, or arylamino group. ] A substrate having a spiral guide groove on one surface, a reflective layer formed on one surface of the substrate, a recording layer formed on the reflective layer, and a protection formed on the recording layer In a write-once optical information recording medium that records and reproduces with a laser beam having a wavelength of 360 to 450 nm, having at least a layer and a light transmission layer formed on the protective layer,
An optical information recording medium, wherein the organic dye used in the recording layer is represented by the following general formula:
[In the formula, Y ⁺ represents the following formula:
(In the formula, at least three of R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ are the same or different alkyl groups, and the other one is the same or different alkyl group or hydrogen atom as the other). Tertiary amine or quaternary ammonium, R ₂ represents an electron-withdrawing substituent, and R ₃ represents an alkyl ether or aryl ether, or an arylamino group. ]