WO2006118266A1

WO2006118266A1 - Optical recording medium, spattering target, and azo-metal chelate dye

Info

Publication number: WO2006118266A1
Application number: PCT/JP2006/309023
Authority: WO
Inventors: Naoyuki Uchida; Hiroyuki Hoshino; Atsushi Komura; Naoki Koda; Akihiko Imagawa
Original assignee: Mitsubishi Kagaku Media Co., Ltd.; Furuya Metal Co., Ltd.
Priority date: 2005-04-28
Filing date: 2006-04-28
Publication date: 2006-11-09
Also published as: TW200710170A; CN101171634A

Abstract

There is provided an optical recording medium for high-density recording or high-speed recording having a preferable recording characteristic in a wide range of recording linear velocity and an excellent light resistance. The optical recording medium includes at least a recording layer formed by an organic dye and a reflection layer containing metal arranged on a substrate having a coaxial or a spiral groove. Recording is performed with the minimum mark length not greater than 0.4 μm or with a recording linear velocity not smaller than 35.0 m/s. The guide groove on the substrate has a track pitch not greater than 0.8 μm, a groove width not greater than 0.4 μm, and a recording layer film thickness in the groove not greater than 70 nm. The organic dye single layer forming the recording layer has a dye holding ratio not greater than 70% in Wool scale 5th grade (light resistance test) of the light irradiation condition shown in ISO-105-B02. The differentiation value dR/dλ (%/nm) of the reflection ratio R of the reflection layer for the wavelength λ in the air is not greater than 3 in the wavelength band from 300 nm to 500 nm.

Description

Specification

Optical recording media, sputtering targets, and azo metal chelate dyes

TECHNICAL FIELD [0001] The present invention relates to an optical recording medium that can be recorded and reproduced by a laser beam, and to a sputtering target and an azo metal chelate dye used in the optical recording medium. More specifically, the present invention has good recording characteristics at a wide recording linear velocity. The present invention also relates to an optical recording medium for high-density recording or high-speed recording that has excellent light resistance, and a sputtering target and an azo metal chelate dye used for the optical recording medium.

Background art

[0002] Currently, various optical recording media such as CD-R, CD-RW, DVD-R, and DVD-RW can store large amounts of information and are easily accessible at random. It is widely recognized as an external storage device in devices and is becoming popular. Furthermore, it is desired to increase the recording density by increasing the amount of information handled.

Among various optical recording media, optical recording media having a recording layer containing an organic dye, such as CD-R and DVD-R, are relatively inexpensive and compatible with optical recording media dedicated to reproduction. In particular, it is widely used.

[0004] In general, current optical recording media have a recording layer made of an alloy thin film layer, an organic dye-containing thin film layer, or the like on a transparent disk substrate, and a reflective layer on the opposite side of the substrate through the recording layer. It has a laminated structure having a protective layer covering these recording layers and reflective layers, and performs recording / reproduction with a laser beam through a substrate.

[0005] As the reflective layer, a metal or alloy thin film is generally used (see Patent Document 1), and gold, silver, a silver alloy or the like is often used among them. Silver, which is the center of these alloys, has been put to practical use because it is relatively inexpensive and provides high reflectivity.

[0006] For the copper alloy, for example, Patent Document 2 describes a reflective layer containing a silver-copper alloy or a silver-paradium mu copper alloy. Patent Document 3 describes that a reflective layer is provided with an alloy thin film containing less than 40% silver on copper. Patent Document 4 describes a copper alloy reflective layer and target containing Ag and Ti. While doing so, they Each of these is an optical recording medium having a low linear velocity recording speed of less than 2. OmZs. Further, the present invention relates to an optical recording medium having a low recording density.

[0007] Patent Document 1: Japanese Patent Publication No. 7-105065

Patent Document 2: JP-A-4-49539

Patent Document 3: Japanese Patent Laid-Open No. 4-364240

Patent Document 4: International Publication No. WO2002Z021524 Pamphlet

Disclosure of the invention

Problems to be solved by the invention

[0008] In recent years, along with the increase in recording density, drive recording has been accelerated, and high-speed recording of 28 mZs has been put to practical use in DVD-R, and development for further high-speed recording has been accelerated. In high-speed recording that is powerful, there is a problem that a recording margin cannot be obtained. This problem is, for example, a phenomenon in which the waveform of the recording mark is distorted as the recording power range in which a good recording jitter value is obtained is narrow, or as the recording power is increased and recorded. Observed.

[0009] The present invention has been made in view of the above problems.

That is, an object of the present invention is an optical recording medium for high-density recording or high-speed recording, has good recording characteristics at a wide recording linear velocity, and is excellent in “practical” light resistance. An optical recording medium is provided.

Another object of the present invention is to provide an optical recording medium suitable for high-speed recording. Another object of the present invention is to provide a sputtering target for producing a reflection layer of an optical recording medium excellent in light resistance and recording characteristics.

Another object of the present invention is to provide a predetermined organic dye used in a recording layer of an optical recording medium suitable for high-speed recording.

Means for solving the problem

[0010] As a result of intensive studies in view of the above problems, the present inventors have found the following items and completed the present invention. In other words, the dye retention before and after the light resistance test when the organic dye forming the recording layer is formed as a single layer is 80% or more, more preferably 90% or more in the recording layer used in the low-speed recording medium. However, for the purpose of high-density recording or high-speed recording Therefore, the composition of the dye is adjusted so that it is 70% or less, which is not good enough for practical use. Using a reflective layer having a composition that is a differential value of reflectivity R with respect to the wavelength of the reflective layer in air dRZd (% / nm) force is 3 or less in the wavelength range of 300 nm to 500 nm. It has been found that by these combinations, an excellent optical recording medium can be obtained not only at high speed recording but also at a wide recording linear velocity, and excellent in “practical” light resistance.

That is, the gist of the present invention is to have a recording layer made of an organic dye and a reflective layer containing a metal on a substrate having concentric or spiral grooves, and the shortest mark length is less than 0. Or 35. In an optical recording medium for recording at a recording linear velocity of OmZs or higher, the track pitch of the guide groove on the substrate is 0. or less, the groove width is 0. or less, and the thickness of the recording layer in the groove. Is less than 70 nm, and the organic dye single layer forming the recording layer has a dye retention power defined by the following definition of the light irradiation condition shown in ISO-105-B02.

It is 70% or less in scale 5 (light resistance test), and the differential value dRZd (% Znm) of reflectance R with respect to wavelength λ in the air of the reflective layer is 3 or less in the wavelength region of 300 nm to 500 nm. The present invention resides in an optical recording medium.

[Dye retention]

The ratio of absorbance before and after the light resistance test at the maximum absorption wavelength of the coating film of the organic dye single layer forming the recording layer in the wavelength range of 300 to 800 nm, that is, {(absorbance after test) / (absorbance before test)} X 100 (%) is the dye retention.

[0012] Another gist of the present invention is that a recording layer containing at least an organic dye and a reflective layer containing a metal are provided on a substrate having concentric or spiral grooves, and the shortest mark length is In an optical recording medium on which recording is performed at a recording linear velocity of 35. OmZs or more, the recording layer contains an azo compound represented by the following general formula (1) and Zn as an organic dye. The optical recording medium comprises at least an azo metal chelate dye composed of the above metal ions.

[Chemical 1]

(In General Formula (1), R ¹ is a hydrogen atom or an ester group represented by CO R ³ (where R ³ is

2

A linear or branched alkyl group or a cycloalkyl group is represented. ). R ² represents a linear or branched alkyl group. At least one of X ¹ and X ² is an NHSO Y group (where Y is a straight chain substituted with at least two fluorine atoms or

2

Represents a branched alkyl group. ) And the rest represent hydrogen atoms. R ⁴ and R ⁵ each independently represents a hydrogen atom, a linear or branched alkyl group, or a linear or branched alkoxy group. R ⁶ , R ⁷ , R ⁸ and R ⁹ each independently represent a hydrogen atom or an alkyl group having 1 or 2 carbon atoms. The NHSO Y basic force H + is removed.

2

NSO Y— (negative) group, and the azo compound represented by the general formula (1)

2

Forms a coordination bond with ON. )

[0013] Another aspect of the present invention is that the reflection of the optical recording medium having a recording layer containing at least an organic dye and a reflective layer containing a metal on a substrate having concentric or spiral grooves. A sputtering target for use in the production of a layer, characterized in that it has at least a material force represented by the following composition B.

[Composition (B)]

50at% ≤Cu≤97at%

3at% ≤Ag≤50at%

0. 05at% ≤X≤10at%

(Where X represents at least one element selected from the group consisting of Zn, Al, Pd, In, Sn, Cr, and Ni, provided that the total amount of Cu, Ag, and X is 100 at% or less. )

[0014] Another aspect of the present invention is to provide a substrate having concentric or spiral grooves, An organic recording medium having a recording layer containing at least an organic dye and a reflective layer containing a metal, wherein the shortest mark length is less than 0, or 35. OmZs or higher An azo metal chelate dye used as a dye, comprising an azo compound represented by the above general formula (1) and a metal ion of Zn.

The invention's effect

[0015] According to the present invention, it has excellent recording characteristics at a wide recording linear velocity, and has excellent "practical" light resistance. An optical recording medium is provided.

According to the present invention, an optical recording medium suitable for high-speed recording is provided.

Furthermore, according to the present invention, there is provided a sputtering target for producing a reflective layer of an optical recording medium having excellent light resistance and recording characteristics.

The present invention also provides an azo metal chelate dye used for a recording layer of an optical recording medium suitable for high-speed recording.

Brief Description of Drawings

1 is a cross-sectional view schematically showing a configuration of an optical recording medium according to an embodiment of the present invention.

FIGS. 2 (a) and 2 (b) are cross-sectional views schematically showing a configuration of an optical recording medium according to an embodiment of the present invention.

[Fig. 3] Fig. 3 (a) is a graph showing the wavelength distribution of the refractive index (n) of the main metal material, and Fig. 3 (b) is the wavelength of the extinction coefficient (k) of the main metal material. (C) is a graph showing the wavelength distribution of reflectance in air calculated for a reflective layer (thickness 120 nm) formed using main metal materials.

[FIG. 4] FIGS. 4 (a) to 4 (d) are diagrams showing the measurement results of recording characteristics and “practical” light resistance of the optical recording media of Example 2 and Comparative Example 1. Fig. 4 (a) is a graph showing the measurement result of the recording power margin, Fig. 4 (b) is a graph showing the measurement result of the asymmetry margin, and Fig. 4 (c) is a measurement result of the bottom jitter before and after the light resistance test. Fig. 4 (d) is a graph showing the measurement results before and after the PImax light resistance test. [FIG. 5] FIGS. 5 (a) to (d) are diagrams showing measurement results of recording characteristics and “practical” light resistance of the optical recording media of Example 3 and Comparative Example 2, Fig. 5 (a) is a graph showing the measurement result of the recording power margin, Fig. 5 (b) is a graph showing the measurement result of the asymmetry margin, and Fig. 5 (c) shows the measurement result of the bottom jitter before and after the light resistance test. Fig. 5 (d) is a graph showing the measurement results before and after the PImax light resistance test.

[FIG. 6] FIGS. 6 (a) and 6 (b) are diagrams showing measurement results of the recording characteristics of the optical recording media of Example 4 and Comparative Example 3, and FIG. 6 (a) shows the recording power. Figure 6 (b) is a graph showing the measurement result of the asymmetry margin.

[FIG. 7] FIGS. 7 (a) to 7 (d) are diagrams showing the recording characteristics and “practical” light resistance measurement results of the optical recording medium of Comparative Example 4, and FIG. Fig. 7 (b) is a graph showing the measurement result of the recording power margin, Fig. 7 (b) is a graph showing the measurement result of the asymmetry margin, Fig. 7 (c) is a graph showing the measurement result of the bottom jitter before and after the light resistance test, and Fig. 7 (d) ) Is a graph showing the measurement results before and after the PImax light resistance test.

FIG. 8 is a graph showing the wavelength distribution of the reflectance of a single metallic reflective layer used in each example and comparative example.

[FIG. 9] FIGS. 9A to 9D are graphs showing the d RZ values of the single metallic reflective layer used in each example and comparative example. Fig. 9 (a) shows a single Cu reflective layer (Example 1), Fig. 9 (b) shows a single Au reflective layer (Example 2), and Fig. 9 (c) shows a single Ag reflective layer (Comparative Example 1). FIG. 9 (d) shows the values of the single A1 reflective layer (Example 5), respectively.

FIG. 10 shows the reflectivity of CuAg and CuAg Pd obtained in Example 6.

12. 8 is a graph showing the measurement results of 12. 9 0.7 together with the measurement results of Ag, Au, and Cu obtained in Example 5.

[Fig.11] Fig.11 (a) and Fig.11 (b) show the dRZd values of CuAg and CuAg Pd, respectively.

12. 8 12. 9 0. 7

It is a graph which shows a calculation result.

FIG. 12 is a graph showing the relationship between the Ag content obtained in Example 6 and the maximum value of dRZd λ in the wavelength region of 300 to 500 nm.

[Figure 13] Figure 13 shows the relationship between the X value (Ag content) and the bottom jitter value in Cu Ag when light resistance is assumed to have a nearly linear correlation with the Ag content. It is a graph.

[FIG. 14] FIGS. 14 (a) and 14 (b) are graphs showing the results of the light resistance test in Examples 6 to 8, and FIG. 14 (a) shows the xenon irradiation time, the jitter value, and the like. Fig. 14 (b) is a graph showing the relationship between xenon irradiation time and PI error.

[Fig. 15] Fig. 15 (a) and Fig. 15 (b) are both graphs showing the results of storage stability tests at high temperatures and high humidity in Examples 6 to 8, and Fig. 15 (a) shows jitter values. Figure 15 (b) is a graph showing the PI error over time.

Explanation of symbols

[0017] 11, 12, 22 Disc for bonding

21 Dummy disk

100, 200, 300, 400, 500 Optical recording media

101, 201, 401, 501 Substrate (1)

102, 402, 502 Recording layer (1)

103, 202, 403, 503 Reflective layer (1)

104, 203 Protective coat layer (1)

105, 204, 407, 504 Adhesive layer

106, 205 Protective coat layer (2)

107, 206, 406, 506 Reflective layer (2)

108, 405, 505 Recording layer (2)

109, 208, 408, 507 Substrate (2)

110, 111, 210, 310, 410, 510 Laser light

207, 303 Recording layer

301 substrate

302 Reflective layer

304, 508 NORIA

305, 404, 504 Transparent resin layer (intermediate layer), adhesive layer (intermediate layer)

BEST MODE FOR CARRYING OUT THE INVENTION

[0018] Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment of the present invention) will be described. This will be described in detail. The present invention is not limited to the following embodiments, and it goes without saying that various modifications can be made within the scope of the gist of the present invention.

[0019] [I. Basic concept of the present invention 1]

In the present invention, first, on a substrate having concentric or spiral grooves, at least a recording layer made of an organic dye and a reflective layer containing a metal, and the shortest mark length is less than 0.4 μm. Or 35. In an optical recording medium for recording at a recording linear velocity of OmZs or higher, the track pitch of the guide groove on the substrate is 0.8 m or less, the groove width is 0.4 μm or less, and the recording layer in the groove Dye retention power of the organic dye single layer forming the recording layer with a film thickness of 70 nm or less as defined below.

It is 70% or less in scale 5 (light resistance test), and the differential value dRZd (% Znm) of reflectance R with respect to wavelength λ in the air of the reflective layer is in the wavelength range of 300 nm to 500 nm. There is provided an optical recording medium characterized by 3 or less (hereinafter sometimes referred to as “first optical recording medium of the present invention”).

[0020] The present inventors have intensively studied to provide an optical recording medium for high-density recording or high-speed recording and having good recording characteristics at a wide recording linear velocity.

It should be noted that “high density recording” in the present invention is premised on recording with a minimum mark length of less than 0.4 m. This is because the problem to be solved by the present invention is a particularly remarkable force in an optical recording medium that is densified by shortening the recording mark and narrowing the track pitch. In "high density recording", it is important to reduce the formation of excessive recording areas.

[0022] In the present invention, "high-speed recording" means recording at a recording linear velocity of 35. OmZs or more (for example, DV D, the DVD speed is 1 ×, that is, the linear velocity of 3.5mZs is 10 times or more. (Recording at rotational speed).

[0023] When the recording of the first optical recording medium of the present invention corresponds to "high-speed recording", the above-mentioned "high-density recording", that is, the minimum mark length of less than 0.4 m is always required. It does not have to be a record of. However, even in this case, the shortest mark length is usually less than 0.5 m, preferably 0.44 / zm. In the following, it is desirable to perform recording at a density in the range of 0.4 m or less.

As a result of the study by the present inventors, it has been found that there are suitable dyes or combinations of dyes as dyes used in the recording layer (dye layer). That is, using a dye having a dye retention of 70% or less after the light resistance test of a single recording layer, or mixing a "dye having poor light resistance" and a "dye having good light resistance" Mixing so that the dye retention before and after the light resistance test of the recording layer is 70% or less.

However, it has been found that such a dye or a combination of dyes suitable for high-density recording at a high density causes a new problem of causing deterioration of light resistance of the disc.

[0026] The present inventors further investigated the new problem. As a result, the differential value dRZd (% Znm) of the reflectance R with respect to the wavelength of the reflective layer in the air is set to 3 or less in the wavelength range of 300 nm to 500 nm. I was able to solve this problem. That is, “practical” light resistance can be improved. Incidentally, the “practical” light resistance in the present invention means that the light resistance of a single recording layer is not good enough, but it is

scale An indicator of whether or not jitter and errors in the recorded part of the disc fall within the preferred range even when irradiated with grade 5 light. Therefore, it is distinguished from the index of dye retention of the recording layer itself.

That is, in the basic concept 1 of the present invention, on a substrate having concentric or spiral grooves, a recording layer made of at least an organic dye and a reflective layer containing a metal are provided, and the shortest mark length is 0. Or 35. In an optical recording medium that performs recording at a recording linear velocity of OmZs or higher, the groove width on the substrate is 0. or less, and the recording layer thickness in the groove is 70 nm or less. Dye retention rate of organic dye monolayer forming the recording layer Force Wool of light irradiation conditions shown in ISO-105-B02

It is 70% or less in scale 5 (light resistance test), and the differential value dRZd (% Znm) of reflectance R with respect to the wavelength of the reflective layer in the air is in the wavelength range of 300 nm to 500 nm. It is characterized by being 3 or less. Here, “dye retention” means the ratio of absorbance before and after the light resistance test at the maximum absorption wavelength of the coating film of the organic dye single layer forming the recording layer in the wavelength region of 300 to 800 nm, that is, {(Absorbance after test) / (Absorbance before test)} X 100 (%).

[0029] By setting the substrate groove width to 0.4 μm or less, the track pitch can be increased to 0.8 μm or less, and a sufficient push-pull signal amplitude can be secured. Therefore, as described above, when recording is performed by rotating the disk at high speed, it is possible to stably track the groove. The groove width is usually not less than 0, more preferably not less than 0, in order to ensure a sufficient push-pull signal amplitude. The track pitch is usually 0.2 μm or more, preferably 0.4 μm or more.

[0030] In addition, when the recording layer thickness in the groove is 70 nm or less, formation of an excessive recording portion is suppressed, and good “high density recording” and “high speed recording” with less crosstalk are possible. It becomes. The film thickness of the recording layer in the groove is usually 5 nm or more, more preferably lOnm or more, and further preferably 20 nm or more.

[0031] In the above high-speed recording, it is usually necessary to form the shortest mark with a pulse whose irradiation time of the laser beam is very short. That is, in powerful high-speed recording, the recording laser light irradiation time for recording the shortest mark length (3T mark in the example of the present embodiment) is less than 8 ns. For this reason, recording at powerful high-speed recording is possible because the bottom jitter (minimum jitter value) does not exceed 9% under the recording conditions where the laser irradiation time during shortest mark length recording is less than 8 ns. This means that the error rate is good enough that there is no problem in reproduction with a commercially available reproduction device. This “recording the shortest mark length with a shortened pulse so that the irradiation time is less than 8 ns” means, for example, that the rise time of the semiconductor laser in the DVD wavelength region is around 4 ns. How severe the recording conditions are.

Note that the irradiation pulse width of the laser for 3T mark length recording used in each of the examples and comparative examples described later is 7.9 ns for 10 × speed recording (35 mZs) and 16 × speed recording (56. OmZs), respectively. And 6.5ns.

In the present invention, “good recording is possible at a wide recording linear velocity” means 3.5. From mZs to approximately 70mZs (for DVD, for example, 1x speed recording of DVD (3.5mZs) to about 20x speed recording (70mZs)) can be recorded without bottom jitter exceeding 9%, or commercially available This means that the reproduction apparatus has an error rate that is good enough to cause no reproduction problems. For example, in DVD-R, the jitter value is a good index for evaluating the recording quality. For example, in the currently known range, it is usually 8.0% or less, more preferably 7% or less, more preferably 6 in 3.5mZs to 28mZs (for example, 1x speed recording to 8x speed recording in DVD). In general, it is determined to be particularly good when recording capable of obtaining a bottom jitter of less than% is possible.

[0034] As a result of intensive studies, the present inventors have found that the problem of the recording margin among the above problems is to reduce the recording speed dependency of the organic color medium and to further increase the response to the shortening pulse. I thought that it can be solved.

[0035] More specifically, according to the study by the present inventors, it is possible to ensure good recording characteristics at a wide recording speed by including a "dye having poor light resistance" in the recording layer, that is, It was clear that there was a correlation between poor light resistance and high-speed recording characteristics, recording characteristics in a wide and recording speed range. This effect is thought to be due to the fact that “light-resistant dyes” can effectively use light energy incident as recording light by decomposing dyes (optical mode). In other words, in a powerful dye, the optical mode is involved in the bond-cleavage reaction of the dye, and light energy is used efficiently, and a recording mark with a sharp edge may be formed, which may improve the recording characteristics. It is done. Alternatively, in general, optical mode recording is known to have a high reaction rate, and in principle, the reaction can be terminated in the order of fsec to psec. If the reaction is completed in this time order, it is highly possible that interference between adjacent marks does not occur in consideration of the rotational speed force of the disc.

On the other hand, the use of incident light as recording light for the reaction of the dye (including decomposition and melting) as thermal energy is generally called heat mode recording.

[0036] In this heat mode recording, there is a limit on the reaction speed due to the heat conduction speed. For example, in DVD-R, it is considered that the reaction usually ends in the order of ns. When the reaction is completed at this order, is the order of the disk rotation speed and the reaction speed comparable? Therefore, the adjacent mark may be affected by heat. When the adjacent marks are affected by heat, so-called thermal interference occurs between the marks, which increases the possibility of deteriorating jitter. However, since this heat mode is not related to light resistance, it is considered that “light-resistant dyes” are mainly decomposed and recorded in this mode.

[0037] Furthermore, by mixing the "dye having poor light resistance" with the "dye having good light resistance", the balance between the physical change and the optical change in the recording portion can be skillfully achieved. It seems possible to improve such high-speed recording characteristics. This is because, for example, the above-mentioned heat mode recording is not likely to occur so much, and “dye with poor light resistance” does not provide a sufficient recording modulation degree. This is because it is thought that it can be supplemented with a dye having good properties.

[0038] It is considered that the above "dye having poor light resistance" corresponds to a state force excited by light, a probable force of causing a so-called "non-radiative transition", and a dye compound. For example, (1) not only has a strong absorption band that is considered to involve π-π * transitions or charge transfer transitions in the vicinity of the recording / reproducing wavelength, but also has a lot of spatial configurations and good flatness. And structural dyes. Examples of this are π-π * transitions that are likely to occur, many of which emit fluorescent light, and include a number of organic dyes. Examples of suitable optical disks include the following specific cyanine dyes. It is done. In addition, metal chelate dyes have been said to have good light resistance. Among the metal chelate dyes, (2) metal chelate dyes whose central metal tends to be desorbed by light due to their light binding properties are “light resistance”. Is considered to fall under "inferior pigment". (2) is the case where the central metal ion, like zinc, does not have an empty d orbital in the outermost d orbital that should be involved in the coordination bond, or there are few empty d orbitals (this In the invention, for example, Zn ²⁺ has a 3d ^lc> electron configuration because 2 electrons can be taken from the electron configuration 3d ^1G 4s ^{2 of} Zn (by ionic ion).) Covalent metal-ligand bonding Power is reduced. Then, electrons are excited in the ligand by photoexcitation, and the central metal tends to be easily detached. As a result, the absorption band may shift to the short wavelength side and the optical constant may change. In addition, when a ligand with a free coordination bond is inferior in light resistance, the ligand tends to react in the optical mode. As in the case of 1) type “dye with poor light resistance”, the optical mode It is thought to have a tendency to record. Therefore, the central metal of such a metal chelate dye having a poor light resistance is a metal having few or no vacant d orbitals due to ions. In addition, the ligand has a molecular orbital in which MLCT (metaH: o-ligand charge transfer) is likely to occur (for example, the ligand has an empty anti-bonding orbital). It is also preferable. The magnitude of the contribution of the optical mode in the decomposition of these dyes can also be estimated based on whether or not fluorescence is emitted. That is, it is considered that dyes that emit fluorescence tend to have a large contribution of optical modes in decomposition. In addition, the covalent bond (strong coordination) between the ligand and the central metal ion is small because the central metal ion has d ⁹ or d ^lc> electron configuration, but the structure selection energy force is close to SO. It can also be thought to be related to something. The “structure selection energy” described above was in accordance with KF Puncell et al, Inorganic Chemistry, 1977, p.550.

[0039] On the other hand, in the "dye having good light resistance", for example, a dye compound having a high probability of non-radiative transition occurs. In such a dye compound, the absorbed light is mainly converted into thermal energy. Such a metal chelate dye is, for example, an azo metal chelate dye which is a first transition element (3d transition element) having an empty d orbital in the d orbital of the central metal ion or capable of forming an empty d orbital. Is mentioned. In these, hybrid orbitals are formed through the overlap of empty d orbitals of metal ions and orbitals of ligands, and the covalent bondability of metal ligands makes it possible to form a chelate structure that is stable even in the excited state. There is a high possibility of being formed. That is, it is considered that the ligand does not release the coordination bond force even by photoexcitation.

[0040] Examples of the "dye having inferior light resistance" include a azo complex having Zn as a central metal, or a cyanine dye containing no quencher. In addition, depending on the type of ligand, an azo complex having Cu or Ni as a central metal may be used, but an azo complex having Zn as a central metal is particularly preferable. Examples of such dyes include metal chelate dyes that coordinate two azo compounds described below with respect to one Zn element.

[0041] The "dye having poor light resistance" in the present invention is preferably a single composition of the dye and having a dye retention of 70% or less as defined in the present invention. Dye retention power small within this range Since it is a “dye having inferior light resistance”, it is preferable because it may be excellent in characteristics at high-speed recording or high-density recording for the reasons described above.

The “dye having good light resistance” in the present invention is preferably a single composition of the dye and having a dye retention rate of more than 70% as defined in the present invention. More preferably, it is 80% or more, and still more preferably 85% or more.

[0043] Preferred as the above "dye having poor light resistance", examples of azo complexes include azo metal chelate dyes comprising an azo compound represented by the following general formula (1) and a metal ion of Zn ( Hereinafter, “Dye (1)” is suitably used.

[0044] [Chemical 2]

In the general formula (1), R ¹ is a hydrogen atom or an ester group represented by CO R ³ (where R ³ is

2

A linear or branched alkyl group or a cycloalkyl group is represented. ).

R ² represents a linear or branched alkyl group.

At least one of X ¹ and X ² is NHSO Y group (where Y is at least 2

2

Represents a straight-chain or branched alkyl group substituted by two fluorine atoms. ) And the rest represent hydrogen atoms.

R ⁴ and R ⁵ each independently represents a hydrogen atom, a linear or branched alkyl group, or a linear or branched alkoxy group.

R ⁶ , R ⁷ , R ⁸ and R ⁹ each independently represent a hydrogen atom or an alkyl group having 1 or 2 carbon atoms.

Note that the NHSO Y basic force is also HSO desorbed to become an NSO Y— (negative) group, and the above general formula (1 The azo compound represented by) forms a coordinate bond with a metal ion.

[0046] R ³ is preferably a straight chain or branched chain having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, or a sec-butyl group. A cycloalkyl group having 3 to 8 carbon atoms, such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a cycloheptyl group. Particularly preferably, a straight chain alkyl group having 1 or 2 carbon atoms such as a methyl group or an ethyl group; a cyclohexane having 3 or more and 6 or less carbon atoms such as a cyclopentyl group or a cyclohexyl group, because steric hindrance is small. An alkyl group;

[0047] R ² is preferably a linear alkyl group having 1 to 8 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group; an isopropyl group, a sec-butyl group, and an isobutyl group. Group, a branched alkyl group having 3 to 8 carbon atoms, such as t-butyl group, 2-ethylhexyl group, cyclopropyl group, and cyclohexylmethyl group.

[0048] Y represents a linear or branched alkyl group substituted with at least two fluorine atoms. The linear or branched alkyl group is preferably a linear or branched alkyl group having 1 to 6 carbon atoms, and more preferably a linear alkyl group having 1 to 3 carbon atoms.

[0049] R ⁴ and R ⁵ are preferably a hydrogen atom, a linear alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 8 carbon atoms. R ⁴ and R ⁵ are more preferably a hydrogen atom, an alkyl group having 1 or 2 carbon atoms, or an alkoxy group having 1 or 2 carbon atoms. The alkyl group and alkoxy group are preferably unsubstituted. R ⁴ and R ⁵ are particularly preferably a hydrogen atom, a methyl group, an ethyl group, or a methoxy group.

[0050] R ⁶ , R ⁷ , R ⁸ and R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 or 2 carbon atoms. It is preferable to use a hydrogen atom or an alkyl group having 1 or 2 carbon atoms because the absorbance and refractive index can be easily adjusted to predetermined values. In the alkyl group having 1 or 2 carbon atoms, the hydrogen atom bonded to the carbon atom may be substituted with another substituent (for example, a halogen atom), but is preferably an unsubstituted alkyl group. Examples of the alkyl group having 1 or 2 carbon atoms include a methyl group and an ethyl group. From the viewpoint of ease of synthesis and three-dimensional structure, R ⁶ , R ⁸ , and R ⁹ are most preferably a hydrogen atom. The

[0051] Specific examples of the azo compound (ligand) of the general formula (1) constituting the dye (1) include

And azo compounds having the structure shown below.

[0052] [Chemical 3]

On the other hand, examples of cyanine dyes preferable as the “dye having poor light resistance” include cyanine dyes represented by the following general formula (2) (hereinafter, referred to as “dye (2)” as appropriate).

[0054] [Chemical 4]

In general formula (2), ring A and ring B may each independently have a substituent, and represent a benzene ring or a naphthalene ring.

R ^1C) and R ¹¹ each independently represents an alkyl group having 1 to 5 carbon atoms which may have a substituent.

R ¹² , R ¹³ , R ¹⁴ and R ¹⁵ each independently represents an alkyl group having 1 to 5 carbon atoms which may have a substituent.

R ¹⁶ represents a hydrogen atom, a halogen atom, a cyano group or an alkyl group having 1 to 5 carbon atoms which may have a substituent.

Q— stands for anti-on. Counter-on includes BF-, PF-, metal complexes, etc.

4 6

There are various keyons.

[0056] Preferably, R ^1C) and R ¹¹ have 1 to 5 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, sec-butyl, etc. It is a straight chain or branched alkyl group. Particularly preferred is a straight-chain alkyl group having 1 or 2 carbon atoms such as a methyl group or an ethyl group because of its small steric hindrance. The hydrogen atom of the alkyl chain may be substituted with fluorine or a substituent described later.

[0057] R ¹² , R ¹³ , R ¹⁴ , and R ¹⁵ are preferably straight-chain alkyl groups having 1 to 5 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group; an isopropyl group, Examples thereof include branched alkyl groups having 3 to 5 carbon atoms such as sec-butyl group, isobutyl group and t-butyl group. The hydrogen atom of the alkyl chain may be substituted with fluorine or a substituent described later.

[0058] R ¹⁶ is preferably a hydrogen atom; a halogen atom such as CI and Br; a cyano group; a methyl group; It is a straight chain or branched alkyl group having 1 to 5 carbon atoms, such as a ru group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, and a sec-butyl group. When an alkyl group is used, the hydrogen atom of the alkyl chain may be substituted with a substituent described later.

[0059] In addition, as a preferable substituent of the benzene ring or naphthalene ring of ring A and ring B, a linear or branched alkyl group having 1 to 6 carbon atoms,

Aromatic or heterocyclic aryl groups having 1 to 12 carbon atoms (carbocyclic or heterocyclic aryl groups having 1 to 12 carbon atoms),

An alkoxy group having 1 to 6 carbon atoms,

An ester group having 1 to 6 carbon atoms,

A dialkylamino group having 1 to 6 carbon atoms,

Nitro group,

A thioalkyl group having 1 to 6 carbon atoms,

An alkylsulfonyl group having 1 to 6 carbon atoms,

A trialkylsilyl group having 1 to 6 carbon atoms,

Sulfonic acid groups,

Phosphate group,

Carboxylic acid groups,

Ciano group,

Halogen atom

Etc.

[0060] Further, R ^1G and R ¹⁶ are preferably substituted on the alkyl group.

An alkoxy group having 1 to 6 carbon atoms,

An ester group having 1 to 6 carbon atoms,

A dialkylamino group having 1 to 6 carbon atoms,

Nitro group, A thioalkyl group having 1 to 6 carbon atoms,

An alkylsulfonyl group having 1 to 6 carbon atoms,

A trialkylsilyl group having 1 to 6 carbon atoms,

Sulfonic acid groups,

Phosphate group,

Carboxylic acid groups,

Ciano group,

Halogen atoms,

Etc.

[0061] The substituent is preferably a carbocyclic or heterocyclic aryl group having 1 to 12 carbon atoms. More preferred is a carbocyclic aryl group having 6 to 12 carbon atoms. From the viewpoint of recording characteristics, a benzene ring is more preferable.

The surface power of recording characteristics is also most preferable. It is preferable to substitute the hydrogen of the alkyl chain with a benzene ring in a part of the alkyl group used for R ^{12 to} R ¹⁶ . Specifically, examples of the method of using a benzene ring as a substituent include the following combinations (1) to (γ). Considering steric hindrance and the like, it is preferable to use a combination of (iii) and (| 8).

[0062] (a) When R ¹² and R ¹³ are alkyl groups, hydrogen in one or both alkyl chains of R ¹² and R ¹³ is substituted with a benzene ring.

(j8) When R ″ and R ¹⁵ are alkyl groups, hydrogen in one or both of R ¹⁴ and R ¹⁵ is substituted with a benzene ring.

When (γ) R ¹⁶ is an alkyl group, the hydrogen of the alkyl chain of R ¹⁶ is substituted with a benzene ring.

[0063] Specific examples of the dye (2) include compounds having the structure shown below.

[0064] [Chemical 5]

Note that any one of the above “dyes having poor light resistance” in the recording layer may be used alone, or two or more may be used in any combination. Among them, it is preferable to use at least one of the above-mentioned dye (1) and Z or dye (2). In this case, only one or two or more of the above-described dye (1) may be used, or only one or two or more of the above-described dye (2) may be used. Any one or more of 1) and the above-described dye (2) may be used in combination as appropriate. Of course, in addition to the above-mentioned dyes (1) and Z or dye (2), another "dye having poor light resistance" may be used in combination.

[0066] On the other hand, it is preferable to combine with the above dye (1) or dye (2). Specifically, as the “dye”, a transition metal other than Zn (for example, V, Cr, Mn, Fe, Co, Ni, Cu) in which two various azo compounds are coordinated is used as a central metal. A metal-containing azo complex is preferred, and the central metal ion forming a coordination bond is preferably a divalent ion.

[0067] Preferably, at least one azo compound selected from the group consisting of compound forces represented by the following general formulas (3), (4), (5), and (6), and a 3d transition element excluding Zn Azo metal chelate dyes (hereinafter referred to as azo metal chelate dyes having azo compounds corresponding to the respective general formulas, “Dye (3)”, “Dye (4)”, “Dye ( 5) ”and“ dye (6) ”.

[0068] [Chemical 6]

[Chemical 8]

In general formulas (3) and (5), is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms which may have a substituent, or a substituent. The straight chain, branched chain! /, Having 1 to 6 carbon atoms may represent an ester group having a cyclic alkyl group.

In the general formulas (4) and (6), R ¹⁷ represents an alkyl group having 1 to 6 carbon atoms which may have a substituent.

R ²¹ to R ²⁷ in general formulas (3) and (4) and R ¹⁸ and R ¹⁹ in general formulas (5) and (6) each independently have a hydrogen atom or a substituent. It represents a straight, branched or cyclic alkyl group having 1 to 6 carbon atoms. R ¹⁸ and R ¹⁹ may combine with each other to form a ring.

In general formulas (3), (4), (5), and (6), at least one of X ¹ and X ² is an NHS OY group (where Y is substituted with at least two fluorine atoms) Linear or branched

2

Represents an alkyl group. ) And the rest represent hydrogen atoms.

The NHSO Y basic force is also removed from H + to form an NSO Y— (negative) group, and the above general formula (3

twenty two

The azo compounds represented by), (4), (5) and (6) form a coordinate bond with a metal ion. )

[0070] R ¹⁷ is preferably a straight chain or branched chain having 1 to 6 carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, sec-butyl, etc. It is an alkyl group.

[0071] R ¹⁸ and R ¹⁹ are preferably a methyl group, an ethyl group, an isopropyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, a hexyl group, and the like. And a linear or branched alkyl group. R ¹⁸ and R ¹⁹ may combine with each other to form a cyclic alkyl group such as a cyclic cyclohexyl group.

[0072] R ² is preferably a hydrogen atom; a straight or straight chain having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, and a hexyl group. Branched alkyl group; straight chain or cyclic having 1 to 6 carbon atoms, such as methyl ester group, ethyl ester group, propyl ester group, isopropyl ester group, butyl ester group, isobutyl ester group, pentyl ester group, cyclohexyl ester group An ester group having an alkyl group. In consideration of industrial synthesis, recording characteristics, etc., R ² is particularly preferably a hydrogen atom.

[0073] R ²¹ and R ²⁷ are preferably hydrogen atoms; carbon numbers such as methyl group, ethyl group, isopropyl group, propyl group, isopropyl group, butyl group, isobutyl group, pentyl group, and hexyl group. 1 or more and 6 or less linear or branched alkyl group;

X ¹ , X ² , and Y may be the same as those of the azo compound represented by the general formula (1)

[0074] The above general formula (3), (4), (5), as substituted alkyl groups R ¹⁷ to R ^27, optionally it may also substituents (6),

An alkoxy group having 1 to 6 carbon atoms,

An ester group having 1 to 6 carbon atoms,

A dialkylamino group having 1 to 6 carbon atoms,

Nitro group, A thioalkyl group having 1 to 6 carbon atoms,

An alkylsulfonyl group having 1 to 6 carbon atoms,

A trialkylsilyl group having 1 to 6 carbon atoms,

Ciano group,

Neurogen atom

Etc.

[0075] Specific examples of the azo compound (ligand) of the general formulas (3), (4), (5), and (6) that constitute a powerful azo metal chelate dye are shown below. Compounds of the structure.

[0076] [Chemical 10]

[0077] [Chemical 11]

It should be noted that any of the above “dyes having good light resistance” may be used alone, or two or more thereof may be used in any combination. Among them, it is preferable to use at least one of the above-mentioned dye (3), dye (4), dye (5) and Z or dye (6). In this case, only one or two or more of the dyes (3), (4), (5) and (6) described above may be used. , (4), (5) and (6), a plurality of them may be used alone or in combination of two or more. Of course, in addition to the above-mentioned dye (3), dye (4), dye (5) and Z or dye (6), another "light-resistant dye" may be used in combination.

[0079] As described above, the light resistance index of a dye whose effect is clear on the recording characteristics is as follows. As described below. That is, when using together the “dye having poor light resistance” and the “dye having good light resistance” constituting the recording layer, the mixing ratio of these dyes is controlled as follows.

. That is, the dye retention rate of the recording layer single layer (the organic dye single layer forming the recording layer) is the light irradiation condition shown in ISO 105-B02, that is, Wool

Mix at a ratio of 70% or less for scale 5

[0080] If the light resistance is better than this value, the sufficient optical mode is not exhibited in the decomposition, so that the contribution of the heat mode (pyrolysis reaction) in the decomposition of the dye is large. It may not be possible to improve the characteristics.

[0081] Note that the dye retention of the single recording layer is determined by the method described in the following example even when the bonded disc is peeled off at the bonded portion and the disc slice having the substrate and the dye that appears. It is possible to evaluate.

[0082] As described above, the combination of the above-described dyes suitable for high-speed recording may deteriorate the light resistance of the disk.

[0083] As a solution for improving the light resistance of a powerful “dye with poor light resistance”, a transition metal chelate compound (eg, acetyl acetyltonate chelate) is generally used as a singlet oxygen quencher. Bisphenol dithiol, salicylaldehyde oxime, bisdithio OC diketone, etc.) and a metal compound and the like may contain a recording sensitivity improver. Here, the metal compound means a compound in which a metal such as a transition metal is contained in the compound in the form of atoms, ions, clusters, etc., for example, an ethylenediamine complex, an azomethine complex, a phenol hydroxylamine complex. Organometallics such as phenantorphine complex, dihydroxyazobenzene complex, dioxime complex, nitrosaminophenol complex, pyridyltriazine complex, acetylylacetonate complex, metaorthocene complex, and volphiline complex Compounds are listed. Although it does not specifically limit as a metal atom, It is preferable that it is a transition metal.

However, the addition of a strong quencher may lose the sharpness of the edge of the recording mark and may complicate the manufacturing process.

[0085] The present inventors have studied to improve "practical" light resistance without using aggressive additives. As a result, a reflective layer is used in which the differential value (dR / d λ) of the reflectance R with respect to the wavelength in the air at a wavelength of 300 nm ≤ λ ≤ 500 nm is (dRZd λ) ≤ 3. As a result, the inventors have obtained the knowledge that the light resistance of the recording layer can be improved.

[0086] The reason is considered as follows. In other words, based on a metal free electron model, when a metal is irradiated with a specific optical frequency, a phenomenon occurs in which electrons in the metal collectively resonate. When this resonance occurs, the refractive index (n), and thus the reflectivity, changes abruptly at a specific frequency. When this electron collective resonance occurs, chemical reaction (including catalytic reaction) easily proceeds due to photoexcitation at the interface with the dye, and the dye is likely to deteriorate. Therefore, it is not desirable from the viewpoint of light resistance that the reflectance fluctuates sharply at a specific light frequency. From this result, it is necessary to select a reflective layer in which (dRZd) ≤3 in the wavelength range described above, that is, not only the absolute value of the reflectance but also the relative value of the reflectance does not change abruptly. Examples of the material that satisfies the strong condition include materials whose band-to-band transition is not in the range of 300 nm to 500 nm. More preferably, (dRZd λ) ≤2, more preferably (dRZ () ≤l. The reason why the specified wavelength range of dRZd is 3 OOnm force and 500 nm will be described below.

[0087] Examples of the reflective layer that satisfy the conditions to be applied include at least one element selected from Cu, Au, and A1 forces (hereinafter, sometimes referred to as "specific element"), and in the reflective layer. Examples include a reflective layer in which the total ratio of these specific elements is 50 at% or more. If this ratio is less than 50 at%, there is a possibility that (dRZc) ≤3 in the above wavelength range may not be satisfied, and therefore sufficient light resistance may not be obtained. Further, as elements other than the above-mentioned specific elements in the powerful reflective layer, preferably Ag, Cr, Ni, Pt, Ta, Pd, Mg, Se, Hf, V, Nb, Ru, W, Mn, Re, Fe And at least one element selected from the group consisting of Co, Rh, Ir, Cd, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi, Ti, Zn, Zr, and rare earth metals. Among them, the ratio of these elements in the reflective layer is preferably 100 at% together with the ratio of the specific elements. It is preferable to adjust the type of elements other than the specific element and the amount of the elements to satisfy (dRZd X) ≤3.

[0088] Also, a reflective layer having a reflectance in air of 20% to 70% at 300 nm to 500 nm is preferable.

This requirement does not mean the force of simply using a reflective layer having a high reflective layer at the recording / reproducing light wavelength as in the prior art. That is, 80% or more at the recording / reproducing light wavelength. It is said that the “practical” light resistance of the recording layer is further improved by using a reflection layer having a reflection layer in the air in the wavelength range of 300 nm to 500 nm of 20% to 70% while having a high reflectivity. Is.

[0089] The reason why the reflective layer satisfying the strong requirements improves the light resistance of the recording layer is considered as follows. In the first place, the light resistance test (ISO-105-B02) for optical disks, which is generally performed, is a test method that assumes exposure to sunlight. It is known that the intensity of sunlight reaches saturation at 300 nm to 500 nm, particularly 400 nm to 500 nm. Also, since the energy of light particles is proportional to the frequency of light, the energy of light particles is also Higher than the energy of long wavelength light particles. Since light particles with high energy have a higher probability of exceeding the threshold for breaking the binding of the dye, it is desirable that the light of this wavelength is not excessively absorbed by the dye in order to improve the light resistance of the disk. In other words, it is preferable to use a reflective layer having a low reflectance in this wavelength range. Therefore, if a reflective layer having a low reflectance in the above wavelength range is used, the amount of multiple reflected light between the dye recording layer and one reflective layer is reduced, so that deterioration of the recording layer having a dye having poor light resistance is suppressed. It is thought that In this way, the “practical” light resistance can be further improved.

[0090] Fig. 3 (a) is a graph showing the wavelength distribution of the refractive index (n) of the main metal material, and Fig. 3 (b) is the wavelength distribution of the extinction coefficient (k) of the main metal material. FIG. 3 (c) is a graph showing the wavelength distribution of reflectance in air calculated for a reflective layer (thickness 120 nm) formed using main metal materials. The film thickness of the reflective layer of 120 nm is a film thickness at which the reflectance is sufficiently saturated. In the present specification, the reflectance “in the air” means the ratio of the return light intensity to the incident light intensity when the incident light is directly irradiated onto the film surface of the reflective layer through the air.

FIG. 3 (a) shows that the refractive index (n) of Au, Cu, and Al is larger in the region of 350 nm to 500 nm than Ag that is generally used as a reflective layer. In particular, the refractive index (n) of Au and Cu is around 1 stably in this wavelength range. Also, from Fig. 3 (c), the reflectivity of Au and Cu is 30% to 70%, which is quite small compared to Ag.

[0092] The values of the refractive index (n) and extinction coefficient (k) of the metal material in Figs. 3 (a) and (b) are as follows: Values listed in the following literature were used.

Springer— Verlag Heidelberg, Landolt Bornstein-Group III Condensed matter, Volume 15, subvolume B, 1985, p.222-236 (Ag-Ca), p.237-248 (Cd-Eu), p.280-29 1

(Ni-Pb) (ISSN: 1616-9549)

[0093] Examples of the reflective layer that satisfy the conditions to be applied include at least one element selected from Cu, Au, and A1 forces (hereinafter sometimes referred to as "specific element"), and in the reflective layer. Examples include a reflective layer in which the total ratio of these specific elements is 50 at% or more. If this ratio is less than 50 at%, the preferred reflectance range may not be satisfied. In addition, as elements other than the above-mentioned specific elements in the powerful reflective layer, Ag, Cr, Ni, Pt, Ta, Pd, Mg, Se, Hf, V, Nb, Ru, W, Mn, Re, Fe And at least one element selected from the group consisting of Co, Rh, Ir, Cd, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi, Ti, Zn, Zr, and rare earth metals. Among them, the ratio of these elements in the reflective layer is preferably 100 at% in combination with the ratio of the specific elements.

[0094] Further, as a result of investigations, for example, in silver or silver alloys that have been put to practical use in the past, the change before and after recording of the recording layer and the reflective layer is different from that during low-speed recording. It was obvious that high-speed recording over Om Zs may be difficult. This is especially true for recordings exceeding 35.Om Zs, because the pulse width of the laser light emitted for recording is shortened, so that optical properties such as plastic deformation, thermal conductivity, absorption and refraction of the reflective layer are reduced. This is because the difference in the constant tends to reflect the recording characteristics more remarkably. Therefore, the selection of the reflective layer for high-speed recording applications requires more caution than in the conventional low-speed recording. However, the present situation is that optical recording media having a reflective layer of silver or a silver alloy are widely put into practical use due to the fact that they have a record of recording characteristics in low-speed recording and are relatively inexpensive.

[0095] As a result of intensive studies, the present inventors have found that recording characteristics at high recording linear velocities (especially 35. OmZs or higher), and at wide recording linear velocities from low to high, differ depending on the reflective layer. For example, by using a reflective layer mainly composed of copper, gold, or aluminum It was found to be good.

[0096] There are various effects that high-speed recording has on recording characteristics. In particular, when the recording layer is made of organic pigment, the recording speed dependency such as recording sensitivity and jitter becomes very remarkable as compared with a recording film medium made of metal or semiconductor. Therefore, as a condition required for a reflection layer of a medium having an organic dye as a recording layer, a reflection layer having a high reflectance of a certain value or higher and higher heat conduction is desired. The metal reflective film having a high reflectance means that the reflective layer is a reflective layer in which the real part n of the refractive index at the recording wavelength is not more than a certain value and the imaginary part k is large. Specifically, the refractive index of the reflective layer for obtaining a practical reflectance is 0.0 <η <1.0 and k> 2.0.

[0097] In addition, it is preferable that the thermal conductivity is high! The above reflectivity is high! In the example of metal, Ag (320W / M · K), Cu (300W / M · K), Au (230W / M · K), Al (158W / M · K) ) And the like.

[0098] By using these metals or alloys thereof, there is a possibility that a medium with good high-speed recording can be obtained. Even when the recording wavelength is shortened in the future, by optimizing the combination of the above metals, there is a high possibility of obtaining good recording characteristics that can achieve both high reflectivity and thermal conductivity.

[0099] Also, in a medium using an organic dye for the recording layer, when a long mark (6 mm mark or more) is recorded, the bottom line of the waveform tends to be inclined rather than horizontal (hereinafter sometimes referred to as waveform distortion). There is.) The waveform distortion may cause the bottom jitter to deteriorate. Despite good bottom jitter at low speed recording, bottom jitter at high speed recording may be bad or vice versa. The present inventors have found that this waveform distortion is related to the temperature distribution in the film thickness direction of the recording layer, which optimizes the combination of the film thickness of the recording layer and the reflective layer, the optical constant, and the thermal conductivity of the reflective layer. As a result, it is considered that good recording is possible at a wide recording linear velocity of 3.5 mZs to 35. Om / s and eventually 3.5 mZs to approximately 70 mZs. RU

[0100] That is, for the reasons described above, the recording mark waveform may be improved in a wide recording linear velocity range by having a reflection layer that can use the recording laser light without waste in a thermal optical manner. There is. [0101] The above-mentioned "reflective layer is mainly composed of copper, gold, and aluminum" means that the reflective layer is made of copper, gold, or aluminum alone, or any of copper, gold, and aluminum. This means that it contains 50 atomic% or more of the combination of two or more. In order to optimize weather resistance, film structure, and optical properties, it is preferable to contain elements other than copper and gold. Examples of such elements include Al, Ag, Cr, Ni, Pt, Ta, Pd, Mg, Se, Hf, V, Nb, Ru, W, Mn, Re, Fe, Co, Rh, Ir, Examples include the group consisting of Cd, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi, Ti, Zn, Zr and rare earth metals. The content of these elements is preferably 0.1 to 40 atomic%. As a material containing such an element, for example, CuAg, CuZrAg and the like are preferable.

[0102] In addition, as described in Examples, copper, gold, and aluminum have a differential value dRZd (% / m) of reflectance of 3 or less with respect to the wavelength in air at a wavelength of 300 nm to 500 nm. In contrast, 300ηπ! The differential value of the reflectance of pure silver at ˜500 nm exceeds 5 at the maximum, which is not preferable for practical light resistance, but for example, even if it is a metal reflective film containing silver, the composition ratio of silver is reduced. Thus, the dRZd X value of the present invention can be 3 or less.

[0103] As explained above, the wavelength is 300ηπ! 35 m / s for the first time by combining a reflective layer with a reflectance dRZd (% Znm) of 3 or less and a recording layer containing a dye with poor light resistance at a wavelength in the air of ~ 500 nm. Thus, an optical recording medium having “practical” light resistance that can withstand practical use while having extremely high recording characteristics as described above can be obtained.

[0104] As described above, in order to form the reflective layer so as to satisfy (dRZd λ) ≤ 3 in the specific wavelength range defined in the present invention, it is necessary to select a sputtering target. The reflective layer contains at least one element selected from Cu, Au and A1 force, and the total ratio of the elements is 50 atomic% in the reflective layer (“atomic%” is described as “at%”) In some cases, it is preferable to set the above. Among Cu, Au, and A1, Cu and A1 are preferred at least from the viewpoint of reflectivity.

[0105] According to the study by the present inventors, the island-like structure of the sputtered film grows during the high-temperature and high-humidity test and the temperature rising process during recording, and the smoothness of the film may be reduced. result However, the fact that the jitter of the recorded portion is sometimes lowered is remarkable.

[0106] From the above, the reflective layer is preferably a thin film containing at least a Cu alloy represented by the following composition (A).

[0107] [Composition (A)]

50at% ≤Cu≤97at%

3at% ≤Ag≤50at%

0. 05at% ≤X≤10at%

(Here, X represents at least one element selected from the group consisting of Zn, Al, Pd, In, Sn, Cr, and Ni. In the following description, when X is referred to as “third element species”, (However, the total amount of Cu, Ag, and X is 100at% or less.)

[0108] Specifically, in the composition (A), the Cu content is usually 50 at% or more, preferably 65 at% or more, more preferably 80 at% or more, and usually 97 at% or less, preferably 95 at% or less. More preferably, it is in the range of 90 at% or less.

[0109] In the above composition (A), the content of! /, Ag is usually 3 at% or more, preferably 5 at% or more, and usually 50 at% or less, preferably 30 at% or less. .

[0110] In order to form the reflective layer to satisfy (dR / d λ) ≤ 3 in the specific wavelength range specified in the present invention, the Ag content should be 50 at% or less. It is preferable that In addition, as supported by the examples described later, the organic dye layer that can withstand high-speed recording as described in the present invention is used as the recording layer, and the effect of improving sufficient light resistance by combining with the reflective layer is further improved. In order to ensure it, it is preferable that the Ag content is 30 at% or less.

[0111] In the composition (A), the content of X is usually 0.05 at% or more, preferably 0.1 at% or more, and usually 10 at% or less, preferably 5 at% or less. . In addition, when two or more metal elements are selected as X, it is preferable that the total of them satisfies the above range.

[0112] The content of the third element species X is preferably 0.05 at% or more. In order to stabilize and easily obtain a sufficient effect, it is more preferably set to 0.3 lat% or more. In particular, Zn has a low melting point, and therefore the amount may not be sputtered when the target is sputtered. Therefore, it is considered preferable that the composition is more than 0.3 lat% as a more stable composition.

[0113] The content of the third element species X is preferably 10 at% or less. If it is 10 &% or less, it is easy to secure a high reflectance. In order to easily ensure a sufficiently high reflectance, the content of the third element species X is more preferably 5 at% or less.

[0114] It is considered that the third element species X has little influence on (dRZd). In other words, the third element species X is preferable for ensuring fine adjustment of the reflectance and storage stability of the reflective layer, rather than being preferable for the light resistance improvement effect of the present invention. .

[0115] Of the third element species X described above, Zn, Al, Pd, In, and Sn are more preferable. Among these, Zn, A1, and Pd are preferable because sufficient reflectance can be easily secured. In particular, Zn was found to have a higher reflectivity even if the addition amount is small, as determined by the present inventors. O In and Sn are also the same as Zn, Al and Pd described above. The power of ^ can be expected. In particular, Zn, In, and Sn form an O component that attacks a Cu alloy and ZnO, In 2 O, and SnO that are conductive oxides.

2 2 3 2

These conductive oxides ZnO, InO, and SnO are n-type semiconductors, and generate a contact potential difference with Cu.

2 3 2

To do. As a result, oxygen ions (0 ^2_ ) are more likely to be attracted to the Zn, In, and Sn sides than Cu, and it is considered that Cu oxides are delayed.

[0116] When a low melting point * low boiling point element is used as the third element type X, a thin film (reflective layer) containing at least a Cu alloy having high reflectivity and excellent storage stability as described above is used. In order to form (manufacture), it is preferable to use the following sputtering target.

[0117] For example, when Zn (melting point: 419.6 ° C, boiling point: 907 ° C) is selected as the third element species X, it is about 0.01 to 2.5 at% higher than the above-mentioned composition (A). It is preferable to contain Zn in the sputtering target. This is because low melting point 'low boiling point elements are easy to volatilize. Although there is a method of suppressing volatilization by making the distance between the target and the substrate during sputtering closer than other places, in order to obtain a predetermined reflective layer more stably and without waste, the sputtering target must be It is particularly preferable that the composition (B) is satisfied. If the composition of the reflective layer and the composition of the target are made the same or close to each other so that the composition (B) can be seen, it becomes easy to produce a reflective layer having the composition (A).

[0118] [Composition (B)] 50at% ≤Cu≤97at%

3at% ≤Ag≤50at%

0. 05at% ≤X≤10at%

(Where X represents at least one element selected from the group consisting of Zn, Al, Pd, In, Sn, Cr, and Ni, provided that the total amount of Cu, Ag, and X is 100 at% or less. Here, the preferable content range of Cu, Ag, and the third element species X is the same as that of the composition (A) described as the composition of the reflective layer.

[0119] The melting point of X is 66.4 ° C for A1, Pd force 550 ° C, 2 31.97 ° C for Sn, and 156.6 ° C for In, in addition to Zn described above. Yes (See Iwanami Science Dictionary 5th Edition, Iwanami Shoten, 1998)

) o

Of the above X, Zn, Al, Pd, In, and Sn are particularly preferable.

[0120] As described above, the sputtering target has a small difference in melting point. Therefore, it becomes possible to omit the production of the mother alloy described in the above-mentioned Patent Document 4 (Patent Document WO 2002Z021524). That is, the following processes are possible. That is, in a high frequency melting furnace, Cu and Ag are put into a crucible at a predetermined ratio, melted in a vacuum, and after the Cu and Ag are sufficiently dissolved, the third element species X is added. Alternatively, Cu, Ag, and third element species X may be put in a crucible at a predetermined ratio in a high-frequency melting furnace and vacuum-melted. At this time, when adding Al, Cr, Ni, Pd, In, and Sn as the third element species X, both Cu and Ag may be added at a predetermined ratio. On the other hand, when adding Zn as the third element species X, it is preferable to add it after Cu and Ag are sufficiently dissolved. This is because the composition tends to become the specified value due to volatilization when initially charging with high vapor pressure V and Zn.

[0121] Here, the melting temperature in the furnace is set to about 1100 ° C to 1200 ° C, and the material of the crucible is C, Al 2 O, MgO or ZrO. Next, pour the molten metal into the bowl,

2 3 2

The melt is cooled in a vertical mold and solidified to produce an ingot. The ingot is removed from the vertical mold and cooled to room temperature. Next, the uppermost feeder part of the ingot is cut and removed, and the ingot is rolled by a compressor to produce a plate-like alloy. Thereafter, the plate-like alloy is cut into a product shape, the front surface of the product is polished, and finally the Cu alloy of the present invention is used. This sputtering target is produced.

[0122] When the above-described master alloy fabrication process is required, the melting point of the main element (Cu in the above sputtering target) and the melting point of the additive element are usually separated by several hundred ° C! /, It is a case that is extremely high. If Ti with a melting point of 1668 ° C is added to a molten main element Cu (approximately 1000 ° C), alloying progresses due to solid diffusion, but the rate is slow and uniform yield is difficult to alloy well. It is. If the ratio of Cu and Ti is 1: 1, the melting point is 960 ° C due to the correlation. Therefore, it is possible to easily alloy the molten main element. However, there are some that do not require parent alloying even if their melting points differ greatly. It is Pd as X. Even if Pd (melting point: 1554 ° C) is added to Ag at a molten metal temperature of 1100 ° C without being mother alloyed, alloying proceeds easily due to the high diffusion rate.

[0123] The sputtering target described above provides an excellent reflective layer as described later. For this reason, from the viewpoint of only the reflective layer formed using the sputtering target, the organic dye to be contained in the recording layer of the optical recording medium using the reflective layer is not particularly limited. Examples of such organic dyes include macrocyclic azanulene dyes (phthalocyanoine dyes, naphthalocyanine dyes, porphyrin dyes, etc.), polymethine dyes (cyanine dyes, merocyanine dyes, squalium dyes, etc.), anthraquinone dyes, azulene dyes. And azo metal chelate dyes and metal-containing indoor-phosphorus dyes. Of these organic dyes, it is preferable to use azo metal chelate dyes or phthalocyanine dyes in consideration of various factors such as productivity, performance, and performance. Preferable examples of the azo metal chelate dyes include azo metal chelate dyes comprising the above-mentioned azo compound having a predetermined structure and Ni and Zn metal ions. However, as described above, the reflection layer exhibits a predetermined effect when used in combination with a recording layer containing a “dye having poor light resistance”.

Next, physical properties at the recording / reproducing wavelength are shown preferably for the recording layer and the reflective layer. It is desirable to maintain an appropriate reflectivity at the laser wavelength at which recording is performed due to restrictions on the drive or optical system used for recording. Also, for example, in DVD-R, the refractive index (n) after recording generally decreases, so the refractive index (n) of the recording layer before recording is high, and the absorption is smaller than a certain amount. This is a necessary condition to ensure sufficient signal amplitude after recording. . Also, if the reflective layer is thin, the transmitted light increases and the components that do not contribute to the signal increase. Therefore, the reflective layer needs to have a film thickness of a certain thickness or more.

[0125] For this purpose, in the recording layer, the refractive index (n) at the recording / reproducing wavelength is 11 ≥1.4, and the extinction coefficient (k W ≤0.3 at the recording / reproducing wavelength) is set in the groove. It is preferable that the film thickness (d) of the film satisfies 0.05 ≤ (nd / λ) ≤ 0.3, and if the reflective layer is not used as a translucent film, The thickness (d) preferably satisfies 50nm≤d≤250nm The upper limit of n is usually 4.0, and the lower limit of k is usually 0.01.

w w

[0126] When the recording layer and the reflective layer satisfy the optical constants and film thicknesses described above, the high reflectivity at the recording / reproducing light wavelength and sufficient signal amplitude after recording necessary for recording by the drive are obtained. be able to.

[II. Embodiment of the Present Invention]

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0128] The first optical recording medium of the present invention is not particularly limited as long as it has the above-described recording layer and reflective layer on a substrate, but is preferably a preferred configuration. Are represented by a configuration in which a recording layer and a reflective layer are sandwiched between two substrates, as represented by the configuration shown in FIGS. 1 (a) and (b), and a configuration shown in FIG. 1 (c). And a structure in which a reflective layer and a recording layer are laminated on a single substrate. Furthermore, the present invention can also be applied to a single-sided two-layer type configuration as shown in FIGS. 2 (a) and 2 (b). FIGS. 1 (a) to 1 (c) and FIGS. 2 (a) and 2 (b) are schematic cross-sectional views showing the layer structure of the optical recording medium according to the embodiment of the present invention.

[0129] The optical recording medium 100 shown in Fig. 1 (a) includes a substrate (1) 101, a recording layer (1) 102, a reflective layer (1) 103, a protective coat layer (1) 104, and an adhesive layer. 105, a protective coat layer (2) 106, a reflective layer (2) 107, a recording layer (2) 108, and a substrate (2) 109 are laminated in this order. Such an optical recording medium 100 includes a substrate (1) 101, a recording layer (1) 102, a reflective layer (1) 103, a protective coating layer (1) 104, a bonding disk 11 and a substrate ( 2) 109, recording layer (2) 108, reflective layer (2) 107, protective coating layer (2) 106, laminating disk 12 in this order, protective coating layer (1) 104 and protective coating layer (2) Adhesive layer 105 with 106 facing each other It is configured by pasting together. The substrate (2) 109 side force is also applied to the recording layer (1) 102 by irradiating the laser beam 110, and the recording layer (2) 108 by irradiating the laser beam 111 from the substrate (1) 101 side. In this case, information recording / reproduction is performed.

[0130] The optical recording medium 200 shown in FIG. 1 (b) includes a substrate (1) 201, a reflective layer (1) 202, a protective coat layer (1) 203, an adhesive layer 204, and a protective coat layer (2 ) 205, a reflective layer (2) 206, a recording layer 207, and a substrate (2) 208 are stacked in this order. Such an optical recording medium 200 includes a dummy disk 21 in which a substrate (1) 201, a reflective layer (1) 202, and a protective coat layer (1) 203 are laminated in this order, a substrate (2) 208, a recording layer 207, a reflective layer The bonding disk 22 having the layer (2) 206 and the protective coating layer (2) 205 laminated in this order is bonded to the protective coating layer (1) 203 and the protective coating layer (2) 205 with the adhesive layer 204 facing each other. It is configured by pasting together. Then, information on the recording layer 207 is recorded / reproduced by irradiating the laser beam 210 with the side force of the substrate (2) 208 as well.

[0131] The optical recording medium 300 shown in FIG. 1 (c) has a layer structure in which a substrate 301, a reflective layer 302, a recording layer 303, a barrier layer 304, and a transparent resin layer 305 are sequentially laminated. Have. In this optical recording medium 300, information is recorded and reproduced on the recording layer 303 by irradiating the laser beam 310 not only on the substrate 301 side but also on the transparent resin layer 305 side (film surface incidence type).

An optical recording medium 400 shown in FIG. 2A includes a substrate (1) 401, a recording layer (1) 402, a reflective layer (1) 403, an intermediate layer 404, and a recording layer (2) 405. A reflective layer (2) 406, an adhesive layer 407, and a substrate (2) 408 are sequentially laminated. Also, the optical recording medium 500 shown in FIG. 2 (b) includes a substrate (1) 501, a recording layer (1) 502, a reflective layer (1) 503, an adhesive layer (intermediate layer) 504, and a barrier layer. 508, a recording layer (2) 505, a reflective layer (2) 506, and a substrate (2) 507 are stacked in this order. In these optical recording media 400 and 500, the substrate (1) 401 and 501 side forces are also irradiated with laser light 410 and 510, whereby the recording layers (1) 402 and 502 and the recording layers (2) 405 and 505 are irradiated. ! /, Information is recorded and played back.

Then, the recording layer (1) 102 and the recording layer (2) 108 of the optical recording medium 100 shown in FIG. 1 (a), the recording layer 207 of the optical recording medium 200 shown in FIG. Recording on optical recording medium 300 shown in c) Layer 303, recording layer (1) 402 and recording layer (2) 405 of optical recording medium 400 shown in FIG. 2 (a), recording layer (1) 502 and recording layer of optical recording medium 500 shown in FIG. 2 (b) (2) As the 505, the above-described recording layer of the present invention can be applied. Further, in combination with these recording layers, the reflective layer (1) 103 and the reflective layer (2) 107 of the optical recording medium 100 shown in FIG. 1 (a), and the reflective layer of the optical recording medium 200 shown in FIG. 1 (b) (1) 202 and reflection layer (2) 206, reflection layer 302 of the optical recording medium 300 shown in FIG. 1 (c), reflection layer (1) 403 and reflection layer of the optical recording medium 400 shown in FIG. 2) As the reflective layer (1) 503 and the reflective layer (2) 506 of the optical recording medium 500 shown in 406 and FIG. 2 (b), the above-described reflective layer of the present invention can be applied.

[0134] Various modifications are made to the configurations of the optical recording media 100, 200, 300 in Figs. 1 (a) to (c) and the optical recording media 400, 500 in Figs. 2 (a), (b). It is also possible. For example, other layers may be provided in addition to the above-described layers, some layers may be omitted, or the stacking order of each layer may be changed without departing from the spirit of the present invention. As a specific example, in the optical recording medium 200 of FIG. 1 (b), the reflective layer (1) 202 and the protective coat layer (1) 203 are omitted, and the substrate 201 is directly attached to the bonding disk 22 by the adhesive layer 204. It may be configured to be bonded. O Furthermore, in the optical recording media 100 and 200 of FIGS. 1 (a) and 1 (b), protective coating layers (1) 104 and 203 and protective coating layers (2) 106 and 205 are provided. Instead, the adhesive layers 105 and 204 having the function of a protective coat layer may be used for bonding.

[0135] As another modification, an ultraviolet curable resin layer, an inorganic thin film, or the like may be formed on the mirror surface side of the substrate to prevent adhesion of dust or the like. Further, a print receiving layer that can be written (printed) on various printers such as ink jet and thermal transfer or various writing tools may be provided on the surface that is not the incident surface of the recording / reproducing light.

[0136] The material of the substrate in the optical recording medium according to the embodiment of the present invention is basically transparent in the wavelength direction of the recording light and the reproducing light in the thickness direction up to the recording layer. That's fine.

[0137] Examples of the material having such a transparent thickness portion include acrylic resin, methacrylic resin, polycarbonate resin, polyolefin resin (especially amorphous polyolefin), polyester resin, polystyrene resin, and the like. A resin layer made of resin such as fat or epoxy resin, glass glass, or a radiation curable resin such as photocurable resin on glass. Digits can be used.

[0138] Injection molded polycarbonate is preferred from the viewpoints of high productivity, cost, moisture absorption resistance, and the like. Amorphous polyolefin is preferred from the standpoint of chemical resistance and moisture absorption resistance. Moreover, a glass substrate is preferable from the viewpoint of high-speed response.

[0139] A resin substrate or a resin layer may be provided in contact with the recording layer, and a guide groove or pit for recording / reproducing light may be provided on the resin substrate or the resin layer. Such guide grooves and pits are preferably provided at the time of forming the substrate, but can also be provided on the substrate using an ultraviolet curable resin layer. In the case of a guide groove force spiral shape, the groove pitch is preferably about 0.1 to 2.0 m.

[0140] The groove depth is measured by AFM (atomic force microscope) and is usually 50 nm or more. Red semiconductor laser light, such as DVD-R, normally has a power of lOOnm or more, especially in the range of low 1x speed (hereinafter sometimes referred to as “IX”) to high speed 8 X recording speed. To be recordable, the groove depth is 120 nm or more. Further, the groove depth is usually 200 nm or less, preferably 180 nm or less. If the groove depth is larger than the above lower limit value, the degree of modulation is low, and if the groove depth is smaller than the upper limit value, it is easy to ensure a sufficient reflectivity. The groove width is measured by AFM (Atomic Force Microscope) and is usually at least 0.10 m, preferably at least 0.20 m. The groove width is preferably 0.40 m or less. For high-speed recording with red semiconductor laser light such as DVD-R, the groove width is more preferably 0.28 m or more and 0.34 m or less. When the groove width is larger than the lower limit, the push-pull signal amplitude can be obtained sufficiently. Moreover, the deformation of the substrate greatly affects the recording signal amplitude. For this reason, if the groove width is made larger than the above lower limit, it becomes easy to suppress the influence of thermal interference and obtain good jitter when recording at a high speed of 8 X or more. Furthermore, the recording power margin is widened and the tolerance for fluctuations in laser power is increased, so that the recording characteristics and recording conditions are improved. When the groove width is smaller than the above upper limit value, thermal interference in the recording mark can be suppressed in low-speed recording such as IX, and a good jitter value is easily obtained.

[0141] Information such as address information, medium type information, recording pulse conditions, and optimum recording power can be recorded on the optical recording medium according to the embodiment of the present invention. These emotions As a form for recording the information, for example, the LPP (Land Pre-Pit) or ADIP (Address in Pre-groove) format described in the DVD-R and DVD + R standards may be used.

[0142] The recording layer material, mixing ratio, and film thickness are as described above. In addition, it is preferable that the film thickness of the part between the grooves is smaller than the film thickness in the grooves.

[0143] Examples of the method for forming the recording layer include generally used thin film forming methods such as a vacuum deposition method, a sputtering method, a doctor blade method, a cast method, a spin coating method, and an immersion method. The spin coating method is preferable from the viewpoint of cost. Also, the vacuum deposition method is preferable to the coating method from the viewpoint of obtaining a recording layer having a uniform thickness.

[0144] In the case of film formation by a spin coating method, after a spin coat where the rotational speed is preferably 10 to 15000 rpm, a treatment such as heating or application to a solvent vapor may be performed.

[0145] The coating solvent for forming the recording layer by a coating method such as a doctor blade method, a casting method, a spin coating method, or a dipping method is not particularly limited as long as it does not attack the substrate. For example, ketone alcohol solvents such as diacetone alcohol and 3-hydroxyl-3-methyl-2-butanone; cellosolve solvents such as methylcetosolve and ethylcetosolve; chain hydrocarbons such as n-hexane and n-octane Solvents; Cyclic hydrocarbon solvents such as cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, n-butylcyclohexane, tert-butylcyclohexane, cyclooctane; tetrafluoropropanol, ota Non-fluoroalkyl alcohol solvents such as tafanolopentanol and hexafnoreorobutanol monole; hydroxycarboxylic acid ester solvents such as methyl lactate, ethyl lactate and methyl 2-hydroxyisobutyrate It is done.

[0146] In the case of the vacuum deposition method, for example, an organic dye and recording layer components such as various additives as necessary are put in a crucible installed in a vacuum vessel, and the inside of the vacuum vessel is filled with an appropriate vacuum pump. After evacuating to about 0 — ² to ₁₀ — ⁵ Pa, the crucible is heated to evaporate the components of the recording layer, and vapor deposited on a substrate placed facing the crucible to form a recording layer.

[0147] In addition to the above-mentioned compounds for improving the stability and light resistance of the recording layer, the recording layer may be a near-infrared laser having a wavelength of about 770 to 830 nm, which is usually used for CD-R, or a DVD-R. A red laser with a wavelength of about 620 to 690 nm, or a wavelength of 410 nm or 51 A recording medium with multiple wavelengths, such as a so-called blue laser of 5 nm, should be used in combination with a dye suitable for recording using each of the recording media to provide an optical recording medium that supports recording with laser light in multiple wavelength ranges. You can also.

[0148] Examples of dyes that can be used in combination include azo dyes or azo metal chelate dyes, cyanine dyes, squalium dyes of the same type as the azo metal chelate dyes having the specific characteristics or structures described above. , Naphthoquinone dyes, anthraquinone dyes, porphyrin dyes, tetrabiborfylazine dyes, indophenol dyes, pyrylium dyes, thiopyrylium dyes, azurenium dyes, triphenylmethane dyes, xanthene dyes, indanthrene dyes Indigo dyes, thioindigo dyes, merocyanine dyes, bispyromethene dyes, thiazine dyes, atrazine dyes, oxazine dyes, indoor diphosphate dyes and the like, and other dyes may be used. Examples of the thermal decomposition accelerator for the dye include metal compounds such as a metal anti-knock agent, a metamouth compound, and an acetylethylacetonate metal complex.

[0149] Further, a noinder, a leveling agent, an antifoaming agent and the like can be used in combination with the recording layer of the present invention, if necessary. Preferable binders include polybutyl alcohol, polyvinyl pyrrolidone, nitrocellulose, cellulose acetate, ketone series resin, acrylic series resin, polystyrene series resin, urethane series resin, polyvinyl butyral, polycarbonate, and polyolefin. Can be mentioned.

[0150] The material and composition of the reflective layer are as described above.

Examples of the method for forming the reflective layer include sputtering, ion plating, chemical vapor deposition, and vacuum vapor deposition.

The thickness of the reflective layer is set to the following range in consideration of recording characteristics and industrial production. That is, the thickness of the reflective layer is usually 50 nm or more, preferably 60 nm or more, while it is usually 300 nm or less, preferably 250 nm or less, more preferably 200 nm or less.

[0151] In addition, the roughness (particle size) of the reflective layer is preferably as small as that of a gold thin film or less from the viewpoint of weather resistance and reflectance. In particular, the recording / reproducing light wavelength is short, and in the case of high-density recording, the roughness of aluminum is likely to increase. Therefore, it is necessary to improve the smoothness by alloying. In order to reduce the roughness of the reflective layer, sputtering Another idea is to reduce the argon pressure at the time.

[0152] The material of the protective layer formed on the reflective layer is not particularly limited as long as it protects the reflective layer from external force. Examples of the organic material include thermoplastic resin, thermosetting resin, electron beam curable resin, and UV curable resin. Examples of inorganic substances include SiO, SiN, MgF, and SnO.

2 4 2 2

[0153] Thermoplastic resin, thermosetting resin, and the like can be formed by dissolving in an appropriate solvent, applying a coating solution, and drying. The UV curable resin can be formed by preparing a coating solution as it is or by dissolving it in a suitable solvent, coating the coating solution, and curing it by irradiating with UV light. As the UV curable resin, for example, an acrylate-based effect such as urethane phthalate, epoxy acrylate or polyester acrylate can be used. These materials may be used alone or in combination, or they may be used as a multilayer film instead of just one layer.

[0154] As a method for forming the protective layer, a coating method such as a spin coating method and a casting method, a sputtering method, a chemical vapor deposition method, and the like are used as in the recording layer. Among these, a spin coating method is preferable. .

[0155] The thickness of the protective layer is usually 0.1 μm or more, preferably 3 m or more. On the other hand, the thickness of the protective layer is usually 100 / zm or less, preferably 30 / zm or less.

[0156] There are no particular restrictions on the laser used for recording and playback, but for example, a dye laser capable of wavelength selection over a wide range in the visible region, a helium-neon laser with a wavelength of 633 nm, and a recently developed wavelength of 680, 660, 650 High power semiconductor lasers around 635 nm, harmonic conversion YAG lasers with a wavelength of 532 nm, blue semiconductor lasers around 405 nm, and the like. Among these, a semiconductor laser is preferable in terms of lightness, ease of handling, compactness, cost, and the like. The optical recording medium according to the embodiment of the present invention enables high-density recording and reproduction at one wavelength or a plurality of wavelengths selected from these.

[0157] Recording on the optical recording medium according to the embodiment of the present invention is usually performed by irradiating a recording layer provided on both sides or one side of the substrate with laser light focused to about 1 μm. As a result of the temperature rise due to the absorption of laser light energy, the recording layer irradiated with laser light undergoes thermal changes in the recording layer, such as decomposition, heat generation, and melting. The optical characteristics change.

[0158] The recorded information is reproduced by irradiating a reproduction laser beam and reading the difference in reflectance between the part and the part where the optical characteristics change.

[III. Basic concept of the present invention 2]

The azo compound represented by the above general formula (1), the metal ion of Zn, and the azo metal chelate dye which is powerful, are the optical recording media described in [I. Basic concept 1 of the present invention] (the present invention). The first optical recording medium is not limited to this, and has a recording layer containing at least an organic dye and a reflective layer containing a metal on a substrate having concentric or spiral grooves, and the shortest mark length is 0. In an optical recording medium for recording at a recording linear velocity of 35.OmZs or more, it can be widely used as an organic dye for the recording layer.

[0160] That is, another optical recording medium of the present invention has a recording layer containing at least an organic dye and a reflective layer containing a metal on a substrate having concentric or spiral grooves. Or an optical recording medium for recording at a recording linear velocity of 35 OmZs or more, wherein the organic dye of the recording layer is an azo compound represented by the general formula (1) A compound based on Zn and a metal ion of Zn and a powerful azo metal chelate dye (this may be hereinafter referred to as “the second optical recording medium of the present invention”). ₀ Second optical recording of the present invention According to the medium, it is possible to obtain an advantage of particularly excellent life characteristics (long-term storage stability and storage stability under high temperature and high humidity).

[0161] The details and specific examples of the azo compound represented by the general formula (1) in the second optical recording medium of the present invention, and the azo compound and Zn metal ion The details and specific examples of the azo metal chelate dye are the same as those described in the above section [I. Basic concept 1 of the present invention].

[0162] Note that, also in the second optical recording medium of the present invention, it is preferable that the reflective layer of the optical recording medium includes the material represented by the composition (A). According to the optical recording medium having such a configuration, it is possible to obtain the advantages that the decrease in reflectance can be suppressed to the minimum and the life characteristics are excellent.

Details and specific examples of the composition (A) in the second optical recording medium of the present invention are also shown above. This is the same as that described in the section of [L Basic concept 1 of the present invention].

[0163] [IV. Basic concept of the present invention 3]

Further, the sputtering target having at least the material represented by the above-mentioned composition B is also used for the reflective layer of the optical recording medium (first optical recording medium of the present invention) described in [I. Basic concept 1 of the present invention]. When the reflective layer is formed in an optical recording medium having a recording layer containing at least an organic dye and a reflective layer containing a metal on a substrate having concentric or spiral grooves, the invention is not limited thereto. It can be used widely.

That is, the sputtering target of the present invention is applied to an optical recording medium having a recording layer containing at least an organic dye and a reflective layer containing a metal on a substrate having concentric or spiral grooves. A sputtering target used for forming the reflective layer, which has at least the material represented by the composition B described above. According to the sputtering target of the present invention, it is possible to provide a high-quality medium that can suppress a decrease in reflectivity to a minimum and is excellent in life characteristics, and can be manufactured at a lower cost.

The details and specific examples of the above-mentioned composition B in the sputtering target of the present invention are the same as those described in the above section [I. Basic concept 1 of the present invention].

[0165] In the sputtering target of the present invention, the organic dye is a light that is an azo metal chelate dye that also has the power of the azo compound represented by the general formula (1) and the metal ions of Ni and Zn. It is particularly preferably used for forming a reflective layer of a recording medium. By using the sputtering target of the present invention for the formation of the reflective layer of such an optical recording medium, there is an advantage that the medium can be manufactured at a low cost without almost changing the conventional manufacturing process.

[0166] [V. Basic Concept of the Invention 4]

In addition, the azo compound represented by the above general formula (1), the metal ion of Zn, and the azo metal chelate dye, which is powerful, are recorded on a substrate having concentric or spiral grooves. A layer and a reflective layer containing a metal, and the shortest mark length is less than 0, or 35. Widely and suitably used as the organic dye of an optical recording medium for recording at a recording linear velocity of OmZs or higher. Is possible. The azo compound represented by the above general formula (1) and the azo metal chelate dye which is composed of Zn metal ions are hereinafter referred to as “the dye of the present invention”. By using the dye of the present invention in the above-mentioned optical recording medium for high-speed recording or high-density recording, there can be obtained an advantage that a low jitter, a low error rate, and a wide recording margin can be achieved as compared with the prior art.

The details and specific examples of the azo compound represented by the above general formula (1) possessed by the dye of the present invention and the details and specific examples of the dye of the present invention are described in [I. Basic concept of the present invention]. This is the same as that described in the section 1].

Example

[0167] Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

[0168] [Measurement method of monolayer dye retention]

In each of the following Examples and Comparative Examples, the dye retention was measured according to the following procedure unless otherwise specified.

First, a polycarbonate substrate having a mirror finish was prepared. Tetrafluoropropoxy O Lovro Bruno V- le concentration 1.4 wt ^_0/0 color containing mixture to be measured (hereinafter referred to as "TFP".) Dissolved solution with the dye layer in the following Examples and Comparative Examples Spin coating was carried out in the same manner as in the above. A small piece of the obtained dye monolayer was cut out and the wavelength dispersion of absorbance was measured using a spectrophotometer (UV-VIS). The maximum value of the obtained absorbance was used as the initial value.

[0169] Next, using a light resistance tester (Suntest XLS + manufactured by Toyo Seiki Co., Ltd.), integrated irradiation satisfying Wool scale class 5 was measured, and the apparatus was calibrated. The small piece of the dye single layer was irradiated with light having the irradiation intensity, and the wavelength dispersion of the absorbance was again measured with a spectrophotometer. The ratio between the maximum absorbance obtained here and the above-mentioned initial value was defined as the dye retention. In each of the following examples and comparative examples, it is possible to irradiate a 2200 W xenon lamp with a radiation intensity of 550 WZm ² for 40 hours.

It was a setting condition that satisfies scale 5.

[0170] [Reflectance measurement method]

In each of the following examples and comparative examples, unless otherwise specified, the reflection of the reflective layer in the air The rate was measured according to the following procedure. That is, using a sample in which the material of the reflective layer was sputtered onto a slide glass, the film surface force was also irradiated with reflectance measurement light (apparatus: Hitachi U3010 spectrophotometer, measurement mode: reflection measurement mode, scan speed: 300 nmZmin, Slit: lnm). From the obtained reflectance measurement value, dRZd λ for wavelength = 300 nm to 500 nm was calculated, and the maximum value dRZd (max) was obtained.

[Example 1]

On a support substrate made of polycarbonate with a thickness of 0.6 mm having a guide groove with a track pitch of 0.774 111, a groove width of 32011111, and a groove depth of 16011111, dye A (an azo system represented by the following structural formula (a)) 40% by weight of azo metal chelate dye comprising two compounds and nickel, and dye B (two ^azo compounds represented by the following structural formula (b) and zinc (divalent ion: Zn ²⁺ ) A recording layer (film thickness in the groove: 50 nm) composed of 60% by weight of the light-absorbing metal chelate pigment) has an absorbance (Optical Density: Absorbance at a wavelength of 598 nm measured with air as a reference). And provided by a spin coating method. The coating solution was a TFP solution having a concentration of 1.3% by weight, and the spin coating rotation speed was 1000 rpm to 2500 rpm. Next, copper (Cu) was deposited thereon by sputtering to form a 120 nm thick Cu reflective layer. At the time of sputtering, the argon pressure was made lower than the well-known conditions for forming the reflective layer, and the input power was increased. Furthermore, on this reflective layer, UV curable resin (KA YARAD manufactured by Nippon Kayaku Co., Ltd.)

SPC-920) was spin coated and cured to form a 10 m protective layer. Two sheets of the laminate thus obtained were prepared, and an optical recording medium was prepared by bonding two sheets using a UV curable adhesive (SK7100, manufactured by Sony Chemical Corporation) so that the substrate was on the outside.

[0172] [Chemical 12]

(a) [0173] The dye retention rates of the dye single-layer coating films of the dye A and the dye B are respectively 90.4

% And 0%, and the dye retention of the recording layer single layer was 56%.

[0174] Further, the reflectivity of the single Cu reflective layer and the value of dRZd λ were measured by the method described above.

The results are shown in the graphs of FIG. 8 and FIG. 9 (a), respectively. 300ηπ of Cu reflective layer single layer! ~ Five

The reflectivity of OOnm was 29% to 56% (Fig. 8). The value of dRZd λ (max) in the same wavelength range was 0.36 (Fig. 9 (a)).

[0175] For the obtained optical recording medium, a DVD-

R

specification for General Ver.2.1 and DVD + R specification

EFM plus modulation random signal with a minimum mark length of 0.4 μm at a recording speed of 56. Om / s (16 times the speed of DVD—R) using the recording pulse strategy conditions compliant with Ver.1.20. Recorded. The irradiation pulse width of the laser for recording the 3T mark length was 6.5 ns. The recorded signal was reproduced using the same evaluator, and the margins (jitter recording power margin and jitter asymmetry margin) were measured. In addition, recording for evaluation of “practical” light resistance (evaluation of recording characteristics before and after xenon irradiation) is performed at 8 × speed, and the minimum value of jitter (data to clock jitter) of the recorded part (best) Jitter characteristic value (hereinafter referred to as “bottom jitter”) and the maximum value of PI (Parity of Inner-code) error (hereinafter referred to as “PI max”) is a DVD-ROM inspection machine (manufactured by Shibasoku Co., Ltd.).

LM2 20A).

[0176] The measurement result of the recording power margin is shown in the graph of Fig. 4 (a), and the measurement result of the asymmetry margin is shown in the graph of Fig. 4 (b). As is clear from FIGS. 4 (a) and 4 (b), the optical recording medium of this example using a Cu reflecting layer had an extremely good bottom jitter of 7%. In addition, the asymmetry margin for which jitter is 9% or less is about 18%, the asymmetry margin for which jitter is 8% or less is 10% or more, and jitter is around 8% even in the vicinity of 5% asymmetry. It was.

[0177] The measurement results before and after the light resistance test for bottom jitter are shown in the graph of Fig. 4 (c), and the measurement result of PI max is shown in the graph of Fig. 4 (d). As is clear from Fig. 4 (c) and (d), C u The optical recording medium of this example using a reflective layer had a slight increase in bottom jitter even after xenon irradiation time of 40 hours (Wool scale grade 5), but PI max did not increase at all. It can be seen that the “practical” light resistance is greatly improved compared to the case of.

[0178] [Example 2]

An optical recording medium was prepared in the same manner as in Example 1, except that the material of the reflective layer was changed to gold (Au) and the film thickness was changed to 90 nm. Recording and reproduction were performed on the obtained optical recording medium under the same conditions as in Example 1, and bottom jitter and PI max before and after the light resistance test were measured.

[0179] The measurement result of bottom jitter is shown in the graph of Fig. 4 (c), and the measurement result of PI max is shown in the graph of Fig. 4 (d). As can be seen from FIGS. 4 (c) and 4 (d), the optical recording medium of this example using the Au reflective layer was slightly less effective than the Cu reflective layer, but good results were obtained. It was.

[0180] Further, the reflectance of the Au reflective layer single layer and the value of dRZd λ were measured by the above-described method.

The results are shown in the graphs of FIG. 8 and FIG. 9 (b), respectively. 300 ηπ single Au reflective layer! The reflectance at ~ 5 OOnm was 37% ~ 50% (Figure 8). The value of dRZd λ (max) in the same wavelength range was 域 .72 (Fig. 9 (b)).

[0181] [Comparative Example 1]

An optical recording medium was manufactured in the same manner as in Example 1, except that the material of the reflective layer was changed to silver (Ag) and the film thickness was changed to 120 nm. Recording and reproduction were performed on the obtained optical recording medium under the same conditions as in Example 1. Margin (recording power margin and asymmetric margin), bottom jitter before and after the light resistance test, and PI

max was measured.

[0182] The measurement result of the recording power margin is shown in the graph of Fig. 4 (a), and the measurement result of the asymmetry margin is shown in the graph of Fig. 4 (b). As is clear from Figs. 4 (a) and (b), the optical recording medium of this comparative example using an Ag reflecting layer has a lower bottom jitter than that of the Cu reflecting layer, and has an asymmetry margin. It can be seen that it is narrow.

[0183] The bottom jitter measurement result is shown in the graph of Fig. 4 (c), and the PI max measurement result is shown in Fig. 4 (d). ) Graphs. As is clear from Figs. 4 (c) and (d), the optical recording medium of this comparative example using an Ag reflective layer is

Under the condition of scale 5 (40 hours of xenon irradiation), both bottom jitter and error (PI max) are bad, and the Ag reflection layer cannot withstand the Wool scale 5 condition. It turns out that it is inferior to light resistance. In addition, error (PI

max) is described as a requirement in the DVD-R standard that it does not exceed 280.

[0184] Further, the reflectivity and dRZd λ value of the Ag reflection layer single layer were measured by the method described above.

The results are shown in the graphs of FIG. 8 and FIG. 9 (c), respectively. 300ηπ of Ag reflection layer single layer! ~ Five

The reflectance of OOnm was 4% to 96% (Fig. 8). The value of dRZd λ (max) in the same wavelength range was 5.6 (Fig. 9 (c)).

[0185] [Example 3]

In Example 1, the dye A was changed to Ni complex dye C (65 wt%) (Ni is a divalent ion: Ni ²⁺ ) in which two azo compounds represented by the following structural formula (c) are coordinated, An optical recording medium was prepared by the same procedure except that the dye B was changed to the cyanine dye D (35% by weight) represented by the following structural formula (d). The film thickness in the groove of the recording layer was 25 nm as confirmed by cross-sectional analysis using an electron microscope. The film thickness of the Cu reflective layer was 120 nm as in Example 1. Recording and reproduction were performed on this optical recording medium under the same conditions as in Example 1, and margins (recording power margin and asymmetry margin), bottom jitter before and after the light resistance test, and PImax were measured.

[0186] [Chemical 13]

[0187] The dye retention ratios of the dye single layer coating films of Dye C and Dye were 97.0% and 0%, respectively, and the dye retention ratio of the recording layer single layer was 68.2%. It was.

[0188] The measurement result of the recording power margin is shown in the graph of Fig. 5 (a), and the measurement result of the asymmetry margin is shown in the graph of Fig. 5 (b). As is clear from Figs. 5 (a) and 5 (b), in the optical recording medium of this example using a Cu reflective layer, the power margin with a jitter of 9% or less is about lOmw and an extremely stable power margin. Is realized. Even if the asymmetry exceeds + 6.0%, it has a jitter of 9% or less, and the asymmetry margin of jitter of 9% or less shows a very wide margin of about 20%. These extremely good margins mean that the thermal degradation (heat storage and thermal interference) of the recording mark is small even at extremely high speed recording of 56 mZs (16 × speed).

[0189] The measurement results of bottom jitter are shown in the graph of Fig. 5 (c), and the measurement results of PI max are shown in the graph of Fig. 5 (d). As is clear from Figs. 5 (c) and 5 (d), the optical recording medium of this example using a Cu reflective layer has much more "practical" light resistance than the case of the Ag reflective layer described later. It can be seen that The dye monolayer contains dye D, which has a dye retention rate of 0%, which is much less resistant to light.

It can be seen that an optical disc with scale 5 “practical” light resistance has been realized.

[0190] [Comparative Example 2]

An optical recording medium was manufactured in the same manner as in Example 3 except that the material of the reflective layer was changed from copper to silver and an Ag reflective layer having a thickness of 120 nm was provided. This optical recording medium was recorded and reproduced under the same conditions as in Example 1, margin (recording power margin and asymmetry margin), bottom jitter before and after the light resistance test, and PI.

max was measured.

[0191] The measurement result of the recording power margin is shown in the graph of Fig. 5 (a), and the measurement result of the asymmetry margin is shown in the graph of Fig. 5 (b). As can be seen in Fig. 5 (a), the recording power margin is much narrower in the optical recording medium of this comparative example using the Ag reflective layer than in the case of the Cu reflective layer.

[0192] The measurement result of bottom jitter is shown in the graph of Fig. 5 (c), and the measurement result of PI max is shown in the graph of Fig. 5 (d). The optical recording medium of this comparative example using an Ag reflective layer is shown in Fig. 5 (c). In Fig. 5 (d), the error (PI max) far exceeds 280. This indicates that the optical recording medium of this comparative example using an Ag reflective layer cannot withstand Wool scale 5 grade.

[0193] [Example 4]

For the optical recording medium of Example 3, the recording speed was changed to 35.0 mZs (equivalent to 10 X), and the irradiation pulse width of the laser for recording the 3T mark length was changed to 7.9 ns. Recording and playback were performed under the same conditions, and margins (recording power margin and asymmetry margin) were measured.

[0194] The measurement result of the recording power margin is shown in the graph of Fig. 6 (a), and the measurement result of the asymmetry margin is shown in the graph of Fig. 6 (b). From FIG. 6 (a), it can be seen that even in this example in which recording was performed with 35. OmZs, very good recording with a bottom jitter of 6.0% was possible as in the case of 56. OmZs recording.

[0195] [Comparative Example 3]

For the optical recording medium of Comparative Example 2, the recording speed was changed to 35. OmZs (equivalent to 10 X), and the irradiation pulse width of the laser for 3T mark length recording was changed to 7.9 ns. Recording and playback were performed under the same conditions, and margins (recording power margin and asymmetry margin) were measured.

[0196] The measurement result of the recording power margin is shown in the graph of Fig. 6 (a), and the measurement result of the asymmetry margin is shown in the graph of Fig. 6 (b). From Fig. 6 (a) and (b), the bottom jitter is relatively good at 6.7%, but the power margin is relatively inferior compared with the optical recording medium using the Cu reflective film of Example 4. I understand that.

[0197] [Comparative Example 4]

In Example 1, “Better light resistance” Ni complex dye E (Ni is 2) in which two “azo compounds” represented by the following structural formula (e) are coordinated with “Blow light resistance” Dye B valence ions: changed to Ni ^2+), a dye a and dye E 50 wt%: except for using mixed at a ratio of 50 wt%, to prepare an optical recording medium by the same procedure as the actual Example 1 . The film thickness in the groove of the obtained recording layer was 30 nm. The film thickness of the Cu reflective layer was 120 nm.

[0198] [Chemical 14]

The dye retention rate of the Dye E single layer coating film was 87.3%, and the dye retention rate of this recording layer single layer was 89.0%.

[0199] This optical recording medium was recorded and reproduced under the same conditions as in Example 1 to obtain a margin.

(Recording power margin and asymmetry margin), bottom jitter before and after light resistance test and PI

max was measured.

[0200] The measurement result of the recording power margin is shown in the graph of Fig. 7 (a), and the measurement result of the asymmetry margin is shown in the graph of Fig. 7 (b). As can be seen from Figs. 7 (a) and 7 (b), even if the reflective layer is a Cu reflective layer, the improvement in characteristics is not seen. The bottom jitter is 9% or more, indicating that both the power margin and asymmetry margin are extremely narrow. In particular, the asymmetry margin is bad – even at a recording power as low as 5%, thermal degradation has already been observed, and the jitter has deteriorated by more than 1% compared to the bottom jitter. The asymmetry margin is preferably 9% or less of jitter at 5%.

[0201] The measurement results of bottom jitter are shown in the graph of Fig. 7 (c), and the measurement results of PI max are shown in the graph of Fig. 7 (d). As is clear from Figs. 7 (c) and (d), the "practical" light resistance was very good.

In addition, when the reflective layer on the recording layer is changed to the same Ag reflective layer as in Comparative Example 1, the bottom jitter in the light resistance test is changed from 6.9% to 7.0%, and the light resistance test is performed. PI

max varied from 5 to 8 respectively, showing very good “practical” lightfastness.

[0202] From the above results, the light of this comparative example using a recording layer containing only a dye having good light resistance was used. For recording media, the thermal degradation is significant for 16x speed recording and extremely high speed recording.

It can be seen that good recording marks are not formed. Even if a Cu reflective layer is used, it is difficult to improve.

[0203] [1x speed recording test]

For the optical recording media of Example 1, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 4 described above, recording and reproduction were performed under the same conditions as in Example 1 except that the recording speed was changed to 1 × speed. This was done and the bottom jitter was measured. The results are shown in Table 1 below.

[0204] [Table 1] Table 1

[0205] Generally, bottom jitter is required to be 9% or less. As is clear from Table 1, the optical recording media of Example 1, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 4 are all good, with bottom jitter of 9% or less in 1x speed recording. Recording characteristics. Nevertheless, superiority and inferiority are seen in high-speed recording as described above.

[0206] From the above results, it can be seen that the optical recording media of the respective examples that satisfy the provisions of the present invention exhibit good recording characteristics at very wide recording speeds such as 1 × speed, 10 × speed, and 16 × speed.

[Example 5] The reflectivity and dRZd λ of the reflective layer (A1 reflective layer single layer) made of aluminum (A1) were measured by the method described above. The results are shown in the graphs of FIG. 8 and FIG. 9 (d), respectively. As is clear from Fig. 9 (d), the dRZd value of the single A1 reflective layer was always 0.1 or less in the range of 300nm to 500nm.

[0208] [Example 6]

Similar to the above [Reflectance measurement method], Cu87.2 atom% ZAgl2. 8 atom% (hereinafter referred to as “CuAg”) and Cu86. 4 atom% ZAgl2. 9 atom% ZPdO. 7 atom %

12. 8

Below, it will be described as “CuAg Pd”. ) And sputter on each glass slide.

12. 9 0. 7

The reflectance was measured from the surface side. The sputtering conditions were the same as in Example 1.

[0209] Fig. 10 shows the measurement results of the reflectance of CuAg and CuAg Pd in [Example 5] etc.

12. 8 12. 9 0. 7

It is a graph shown with the measurement result of Ag, Au, and Cu obtained in above. In FIG. 10, the horizontal axis represents wavelength (nm), and the vertical axis represents reflectance (%). From Fig. 10, CuAg and

12. 8

CuAg Pd has optical properties that are clearly different from those of Cu.

12. 9 0. 7

You can see that the reflectivity is a little closer.

[0210] The dRZd λ of CuAg and CuAg Pd was also calculated. Fig. 11 (a), (b)

12. 8 12. 9 0. 7

Are graphs showing the calculation results of dRZd for CuAg and CuAg Pd, respectively.

12. 8 12. 9 0. 7

is there. Fig. 11 (a), (b) The force that increases the noise so that the force is also increased. The maximum value of dR Zd of Ag 5.6 Wavelength range of 300 to 500 nm where the peak wavelength of 6 exists ( In Fig. 9, there is a slight increase in dRZd noise.

[0211] Here, from the reflectivity R of Ag in Comparative Example 1 and the reflectivity R of Cu in Example 1, Cu (A

The reflectance R (Cu Ag) at each wavelength of Ag Cu 1 -X) g (atomic%: at%) was calculated by the following formula.

X (1 -X) X

R (Cu Ag) =

(1 -X) x

{(1 -X) / 100} XR (Cu) + (X / 100) XR (Ag)

[0212] As a result, a spectrum showing the wavelength dependence of the reflectance as shown in Fig. 10 is obtained when the mixing ratio of Ag and Cu is arbitrary. Then, dRZd λ was calculated in the same manner as in FIG. 11 (a) for the predetermined mixing ratio of Ag and Cu, and the maximum value of dR / d at 300 to 500 nm was obtained. Here, a graph obtained by plotting the maximum value of dRZd λ in the wavelength range of 300 to 500 nm obtained by the above procedure on the vertical axis is the content of Ag on the horizontal axis. Shown in Figure 12. As shown in the figure, 300ηπ! It can be seen that there is a correlation between the maximum value of dRZd seen at ~ 500nm and the amount of Ag. From the figure, it can be said that the dRZd force ^ is when Ag is approximately 50at%.

[0213] On the other hand, (11)

12. 8 ^ 7 (The actual value of the maximum value of 1 (Fig. 11 (&

)), The actual measured value of dRZd at 300 to 500 nm in Cu (100 at%) (see Fig. 9 (a)), and the maximum value of dRZd λ from 300 to 500 nm in Ag (100 at%) ( Measured force in Fig. 9 (c)) Assuming that dR / d λ is 3, the Ag amount is approximately 50 at%. In other words, it can be said that the actual measurement results are in good agreement with the previous calculation results. In other words, the maximum value in the 300 to 500 nm wavelength range of dRZd derived from Ag is reduced by adding a metal with a small dRZd value in the 300 to 500 nm wavelength range, such as Cu, Al, Au, etc., to Ag. You can see that Therefore, it can be seen that if the Ag content is 50 at% or less, the maximum value of dRZd λ in the wavelength range of 300 to 500 nm can be controlled to 3 or less.

[0214] Whether or not sufficient light resistance can be obtained was compared between the case where the reflection layer was Cu and the case where the reflection layer was Ag at a xenon irradiation time of 40 hours in Fig. 4 (c). As shown above, the maximum value of dR / d in the wavelength range of 300 to 500 nm has a substantially linear correlation with the Ag content. For this reason, assuming that the light resistance has an almost linear correlation with the Ag content, a jitter value of 13% that can be reproduced by the player was set as an allowable limit for jitter deterioration. The bottom jitter values after 40 hours of xenon irradiation in an optical recording medium with the reflective layer made of Cu (100 at%) and an optical recording medium with the reflective layer made of Ag (10 Oat%) are plotted in FIG. did. In other words, Fig. 13 shows Cu Ag under the above assumption.

5 is a graph showing the relationship between the value of X (Ag content: at%) and the bottom jitter value in (100-X) X. From Fig. 13, it is considered that the upper limit of the Ag content at which good jitter characteristics are easily obtained is approximately 30 at%.

[0215] Next, in Example 1, the Cu reflective layer was changed to CuAg and CuAg Pd, respectively.

12. 8 12. 9 0. 7

The optical recording medium (hereinafter referred to as “CuAg DVD-R” and “CuAg” respectively)

12. 8

g Pd DVD—R ”. ) Was produced. And these optical recording media

12. 9 0. 7

After recording at 8 times speed, the light resistance test was performed in the same way as in Example 1 (however, when xenon was irradiated) The interval was 120 hours. ). The results are shown in the graphs of Fig. 14 (a) (jitter value) and Fig. 14 (b) (PI error). In all cases, no deterioration was observed, and it was found to be very good and to have the same effect as the copper alloy force SCu reflective layer.

[0216] Furthermore, CuAg DVD-R¾tJ ^ CuAg Pd DVD— R was tested for storage stability.

12. 8 12. 9 0. 7

An experiment was conducted. Storage stability test (sometimes referred to as life test) uses a constant temperature and humidity chamber (SH-641 manufactured by ESPEC) and keeps optical recording media at 80 ° C and relative humidity 85% for 875 hours. It was done by doing. CuAg DVD—R and CuAg Pd DV

12. 8 12. 9 0. 7

The results of the storage stability test of D—R at high temperature and high humidity are shown in the graphs of Fig. 15 (a) (jitter value) and Fig. 15 (b) (PI error). In Fig. 15 (a) and (b), CuAg DVD—R is set to “CuAg”.

12. 8 12.8 and CuAg Pd DVD—R is shown as “CuAg Pd”. None of the deterioration

12. 9 0. 7 12. 9 0. 7

It was always small and very good.

[Example 7 and Example 8]

The CuAg reflective layer or CuAg Pd reflective layer of Example 6 is

12. 8 12. 9 0. 7 12. 8 1. 1 Injection layer and CuAg Zn

12. 9 10.6 Optical recording media were fabricated in exactly the same manner except that the reflective layer was changed (hereinafter referred to as CuAg Zn DVD—R (Example 7), CuAg Zn DVD—R (Example

12. 8 1. 1 12. 9 10. 6

8) In some cases. ) ₀

[0218] For each optical recording medium, a light resistance test was performed in the same manner as in Example 6 (results shown in Fig. 14

It is shown in (a) and Fig. 14 (b). ) And storage stability test at high temperature and high humidity (The results are shown in Fig. 15 (a) and Fig. 15 (b)).

[0219] Storage stability in light resistance test when CuAg Zn is included in the reflective layer

12. 8 1. 1

In the test, CuAg of Example 6 was included in the reflective layer and CuAg Pd

As in the case of having 12. 8 12. 9 0. 7 in the reflection layer, extremely good characteristics were exhibited. On the other hand, when CuAg Zn is included in the reflective layer, the storage stability at high temperature and high humidity is good for other optical recording media.

12. 9 10. 6

There was a tendency to be slightly inferior to the body. The reason for this is not good enough, but there seems to be room for improvement.

[0220] [Example 9]

A sputtering target was produced in accordance with the melting method in vacuum described below. [0221] First, in a high-frequency melting furnace, Cu and Ag were put into a crucible at a predetermined ratio and melted while sufficiently vacuuming. At this time, when adding Pd (Example 6), Al, Cr, Ni (Example 9), and In, Sn (Example 10 described later) as the third element species X, together with Cu and Ag, a predetermined element Added in proportions. On the other hand, when Zn (Examples 7, 8, 9 and Example 10 described later) was added as the third element species X, it was added after Cu and Ag were sufficiently dissolved. This is because the composition does not reach the specified value due to volatilization when Zn with high vapor pressure is initially charged.

[0222] The melting temperature in the furnace was 1100 to 1200 ° C. The crucible is C, Al 2 O, MgO or ZrO

2 3 2 etc. were used.

Melting of the molten metal was performed by pouring into a Fe or C cage having alumina or magnesium talc applied on the inner surface.

In order to prevent shrinkage of the vertical type, the feeder was heated to about 300 ° C to 500 ° C with a heater in advance before pouring, and the lower force was solidified unidirectionally toward the upper part.

[0223] The melt is cooled and solidified in a vertical mold to produce an ingot, and the ingot is rolled by a rolling mill to obtain a plate shape of 90 (mm) X 90 (mm) X 8.1 (mm) An alloy was prepared.

[0224] Thereafter, in a state where Ar gas was sealed at 400 ° C to 500 ° C in an electric furnace, the plate-like alloy was heat-treated for about 1 to 1.5 hours, and then warpage was further corrected by a press.

And the corrected board was wire-cut into a product shape. The front surface of the product was polished with water-resistant abrasive paper to adjust the surface roughness, and finally a Cu alloy sputtering target was produced.

[0225] Incidentally, the degree of vacuum was maintained at ^{1. 3 X 10 _2 Pa (l} X 10 _4 Torr) following a high vacuum. This is because Ag and Cu are easy to contain oxygen in the molten metal, and are intended for deoxidation when the molten metal is held under reduced pressure. However, since the volatilization of Ag progresses under reduced pressure, various atmosphere adjustments were made according to the situation.

By the above method, a sputtering target having the yarn composition shown in Table 2 below was produced.

[0226] [Table 2] Table 2

[0227] In order to examine the storage stability and the reflectance tendency of the target having the above composition and the sputtered film, the following experiment was conducted. That is, a sputtered film with a thickness of 150 nm, which is thicker than usual, was formed on a glass substrate under the following sputtering conditions. And the reflectance when 650 nm light was irradiated from the film surface side was measured. The reflectivity was measured immediately after film formation and after being kept for 24 hours under high temperature and high humidity at 80 ° C and 80% relative humidity. The correlation between the reflectance and the target composition can be known from the measurement result of the reflectance immediately after the film formation. In addition, the results of extremely strict storage stability tests can be obtained by measuring the change in reflectivity after holding at high temperature and high humidity for 24 hours and immediately after film formation. The spectroscope used for the above reflectance measurement was UV-3100PC manufactured by Shimadzu Corporation.

[0228] <Sputtering conditions>

Sputtering equipment = ULVAC (ULVAC) BC4341

Ultimate vacuum = 5 X 10 " ⁴ Pa

Ar gas pressure = 0.3 Pa

Sputtering power (maximum value) = 200W

[0229] Table 2 shows the measurement results of the reflectivity immediately after film formation, the measurement results of the reflectivity after being held for 24 hours under high temperature and high humidity, and the measurement results of the change in reflectivity. In Table 2, “timeO” indicates “Reflectance measurement result immediately after deposition”. In Table 2, “After 80 ° C 80% RH2 4 hr” indicates “Reflectance measurement results after holding at high temperature and high humidity for 24 hours”. In Table 2, “Reflectance change” is indicated as “Measurement result of reflectivity change”. [0230] In Table 2, the effect of improving the storage stability by the addition of the third element species X clearly appears compared with the binary system of Cu and Ag. That is, for example, Cu Ag reduces the reflectivity.

87. 2 12. 8

Force tends to increase to 26. 8%, while Cu Ag Al, Cu Ag Zn

84. 8 12. 7 2. 5 86. 1 12. 8

, Cu Ag Cr, Cu Ag Ni reflectivity drop is 5 · 96%,

1. 1 85. 9 12. 8 1. 3 85. 3 12. 8 1. 2

2. 23%, 5. 05%, 3. 28%, / J, sneak. In addition, as shown in Table 2, higher reflectivity (over 90%) is obtained for the third element species X in the case of Al, Zn, and Cr. Among them, A1 and Zn have high reflectivity. It turns out that it is preferable. On the other hand, as verified in A1, when adding the third element species X to the CuA g alloy, if the content of the third element species X exceeds 10 at%, the change in reflectance tends to be large. Recognize.

[0231] As the third element type X, when two or more kinds of metal elements are used as long as they are one kind or more, the total sum may be set to 10 at% or less.

[Example 10]

In the same manner as in Example 9, a sputtering target having the composition described in Table 3 below was produced. Furthermore, the following experiments were conducted to investigate the acid resistance and corrosion resistance of the sputtering target and the sputtered film. That is, a sputtered film was provided on the glass substrate as in Example 9. Then, the reflectance of the sputtered film provided on the glass substrate was measured by the same method as in Example 9, and then the H 2 S gas atmosphere having a concentration of lOOppm.

2

For 2 hours. Then, the reflectance after holding was measured again in the same manner as in Example 9. The light of 650 nm for reflectance measurement was incident from the substrate side. Table 3 shows the results obtained in the above experiment.

In Table 3, “immediately after sputter film formation” indicates the reflectance measurement result immediately after the sputtering film is formed on the glass substrate. Also, in Table 3, the force indicated as “after exposure” is the measurement result of the reflectivity after holding in the H 2 S gas atmosphere for 2 hours.

2

Showing the results. Table 3 shows the change rate of reflectivity between the power indicated as “change rate” and “immediately after sputter film formation” and “after exposure”.

[0234] [Table 3] Table 3

[0235] From the results shown in Table 3, when Cu is contained in Ag at 10at% or less and the third element species X is contained in 5 &% or less, it can be used for extremely severe acid and corrosion tests such as HS gas exposure. Regardless, it can be seen that most of the reflectance change rate can be controlled to a very small value of several percent. Note that the content of the third element species X of 5 at% or less is smaller than the additive amount conventionally used. This also shows that even when the third element type X is 5 at% or less, the above-mentioned reflective layer exhibits the effect of improving the acid resistance and the resistance to corrosion.

Industrial applicability

[0236] The present invention can be suitably used in applications such as an optical recording medium for red semiconductor lasers such as DVD player R, an optical recording medium for blue semiconductor lasers, and the like.

[0237] The power of the present invention in detail using specific embodiments [0237] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the invention.

This application consists of a Japanese patent application filed on April 28, 2005 (Japanese Patent Application No. 2005-131 925) and a Japanese patent application filed on April 27, 2006 (Japanese Patent Application 2006— 124 059), which is incorporated by reference in its entirety.

Claims

The scope of the claims

[1] On a substrate having concentric or spiral grooves, at least a recording layer having an organic coloring power and a reflective layer containing a metal, and the shortest mark length is less than 0.4 m, or 35. In an optical recording medium for recording at a recording linear velocity of OmZs or more, the track pitch of the guide groove on the substrate is 0.8 m or less, the groove width is 0.4 m or less, and the recording layer thickness in the groove Is less than 70nm,

The organic dye single layer forming the recording layer has a dye retention rate of 70% or less in the Wool scale 5 (light resistance test) under the light irradiation conditions shown in ISO-105-B02, as defined below.

The differential value of reflectivity R with respect to the wavelength of the reflective layer in air dRZ (% / nm) 1S In the wavelength range of 300 nm to 500 nm!

An optical recording medium characterized by the above.

[Dye retention]

The ratio of the absorbance before and after the light resistance test at the maximum absorption wavelength of the coating film of the organic dye single layer forming the recording layer in the wavelength range of 300 to 800 nm, that is, {(absorbance after test) / (absorbance before test)} X 100 (%) is the dye retention.

[2] The reflective layer contains at least one element selected from Cu, Au, and A1, and the total ratio of the elements is 50 at% or more in the reflective layer.

The optical recording medium according to claim 1, wherein:

[3] Wavelength of the reflective layer is 300ηπ! Reflectance in air at ~ 500nm is 20% or more and 70% or less

The optical recording medium according to claim 1, wherein the optical recording medium is characterized in that

[4] The recording layer contains at least a azo metal chelate dye comprising an azo compound represented by the following general formula (1) and a metal ion of Zn as an organic dye.

The optical recording medium according to any one of claims 1 to 3, wherein the optical recording medium is characterized in that

[Chemical 1]

(In general formula (1),

R ¹ is a hydrogen atom or an ester group represented by CO R ³ (where R ³ is a straight chain or

2

Represents an alkyl group or a cycloalkyl group. ).

R ² represents a linear or branched alkyl group.

At least one of X ¹ and X ² is NHSO Y group (where Y is at least 2

2

Note that the NHSO Y basic force is also HSO desorbed to become an NSO Y— (negative) group, and the above general formula (1

twenty two

The azo compound represented by) forms a coordinate bond with a metal ion. )

The recording layer contains at least a cyanine dye represented by the following general formula (2) as an organic dye.

The optical recording medium according to any one of claims 1 to 4, wherein the optical recording medium is characterized in that

[Chemical 2]

(In general formula (2),

Ring A and ring B each independently have a substituent and represent a benzene ring or a naphthalene ring.

R ^1G and R ¹¹ each independently represents an alkyl group having 1 to 5 carbon atoms which may have a substituent.

R ¹⁶ represents a hydrogen atom, a halogen atom, a cyano group, or an alkyl group having 1 to 5 carbon atoms which may have a substituent.

Q— stands for anti-on. )

The recording layer is an organic dye, and is a compound represented by the following general formulas (3), (4), (5), (6): 3d transitions excluding Zn and at least one azo compound selected from the group consisting of also a compound force Contains at least a azo metal chelate dye consisting of elemental metal ions

5. The optical recording medium according to claim 4, wherein:

[Chemical 3]

R ²⁶ R ²⁵ [Chemical 4]

(In the general formulas (3) and (5), R ² has a hydrogen atom, a linear, branched or cyclic alkyl group having 1 carbon atom which may have a substituent, or a substituent. Or a straight-chain, branched or ester group having a cyclic alkyl group having 6 to 6 carbon atoms, and in formulas (4) and (6), R ¹⁷ may have a substituent. C1-C6 alkyl Represents a ru group.

2

Represents an alkyl group. ) And the rest represent hydrogen atoms.

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6. The optical recording medium according to claim 5, wherein:

[Chemical 7]

[Chemical 8]

(In the general formulas (3) and (5), is a hydrogen atom, a linear, branched or cyclic alkyl group having 1 carbon atom which may have a substituent, or a substituent. A linear, branched or branched alkyl group having 1 to 6 carbon atoms represents an ester group having a cyclic alkyl group In the general formulas (4) and (6), R ¹⁷ is a carbon which may have a substituent. Number 1 to 6 Represents a ru group.

2

Represents an alkyl group. ) And the rest represent hydrogen atoms.

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It has a recording layer containing at least an organic dye and a reflective layer containing a metal on a substrate having concentric or spiral grooves, and the shortest mark length is less than 0.4 m, or 35. In an optical recording medium for recording at a recording linear velocity of OmZs or higher, an azo metal chelate dye comprising an azo compound represented by the following general formula (1) and a metal ion of Zn is used as the organic dye in the recording layer. Contain at least

An optical recording medium characterized by the above.

[Chemical 11]

(In general formula (1),

2

Represents an alkyl group or a cycloalkyl group. ). R ² represents a linear or branched alkyl group.

At least one of X ¹ and X ² is NHSO Y group (where Y is at least 2

2

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The azo compound represented by) forms a coordinate bond with a metal ion. )

The reflective layer contains at least a material represented by the following composition (A)

The optical recording medium according to any one of claims 1 to 8, wherein the optical recording medium is characterized by that.

[Composition (A)]

50at% ≤Cu≤97at%

3at% ≤Ag≤50at%

0. 05at% ≤X≤10at%

(Where X represents at least one element selected from the group consisting of Zn, Al, Pd, In, Sn, Cr, and Ni, provided that the total amount of Cu, Ag, and X is 100 at% or less. V) Sputtering target used for manufacturing the reflective layer of an optical recording medium having a recording layer containing at least an organic dye and a reflective layer containing a metal on a substrate having concentric or spiral grooves. Because

At least the material represented by the following composition B

A sputtering target characterized by that.

[Composition (B)]

50at% ≤Cu≤97at%

3at% ≤Ag≤50at%

0. 05at% ≤X≤10at%

(Where X is at least one selected from the group consisting of Zn, Al, Pd, In, Sn, Cr, Ni) Represents the element of However, the total amount of Cu, Ag, and X is 100at% or less. )

[11] As the organic dye, an azo compound represented by the following general formula (1) and a azo metal chelate dye which is powerful with Ni and Zn metal ions are used.

The sputtering target according to claim 10, wherein

[Chemical 12]

(In general formula (1),

2

Represents an alkyl group or a cycloalkyl group. ).

R ² represents a linear or branched alkyl group.

At least one of X ¹ and X ² is NHSO Y group (where Y is at least 2

2

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The azo compound represented by) forms a coordinate bond with a metal ion. )

A recording layer containing at least an organic dye and a reflective layer containing a metal on a substrate having concentric or spiral grooves, and the shortest mark length is less than 0.4 m, or Or 35. an azo metal chelate dye used as the organic dye of an optical recording medium for recording at a recording linear velocity of OmZs or higher,

Consists of an azo compound represented by the following general formula (1) and a metal ion of Zn

An azo metal chelate dye characterized by the above.

[Chemical 13]

(In general formula (1),

2

Represents an alkyl group or a cycloalkyl group. ).

R ² represents a linear or branched alkyl group.

At least one of X ¹ and X ² is NHSO Y group (where Y is at least 2

2

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The azo compound represented by) forms a coordinate bond with a metal ion. )