JP2008300007A - Optical information recording medium and information recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical information recording medium as a blue-ray disc having satisfactory recording characteristics in recording by short wavelength laser beam irradiation and easy to manufacture. <P>SOLUTION: The optical information recording medium has a reflection layer, a recording layer, a barrier layer, and a cover layer in this order on the surface of a substrate having a pregroove thereon. The recording layer contains a compound which is represented by a formula of a compound and has a pyrolytic property where a mass loss rate in a main loss process in thermal mass analysis is 10% or more. Between the barrier layer and the cover layer, a layer having a glass transition temperature not higher than 25°C is formed by curing a UV curing composition. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical information recording medium capable of recording and reproducing information using a short wavelength laser beam, and more particularly to a Blu-ray optical information recording medium. Furthermore, the present invention relates to a method for recording information on the optical information recording medium.

  Conventionally, a write-once CD (CD-R) and a write-once DVD (DVD-R) are known as optical information recording media capable of recording information only once with a laser beam. Information recording on a CD-R is performed by a near-infrared laser beam (usually a wavelength of about 780 nm), whereas information recording on a DVD-R is performed by a visible laser beam (about 630 to 680 nm). Is called. Since DVD-R uses laser light having a shorter wavelength than CD-R as recording laser light, DVD-R has the advantage that high-density recording is possible compared to CD-R. Therefore, in recent years, DVD-R has secured its position as a large-capacity recording medium to some extent.

In recent years, networks such as the Internet and high-definition TVs are rapidly spreading. In addition, there is an increasing demand for a large-capacity recording medium for recording image information inexpensively and easily, with the upcoming broadcast of HDTV (High Definition Television). However, it cannot be said that the CD-R and DVD-R have a recording capacity that is large enough to meet future requirements. Therefore, in order to improve the recording density by using a laser beam having a shorter wavelength than that of the DVD-R, development of a large-capacity optical disc capable of recording with a short wavelength laser (for example, a wavelength of 440 nm or less) is in progress. As such an optical disc, for example, an optical recording disc (Blu-ray Disc, hereinafter also referred to as “BD”) called a Blu-ray system using a 405 nm blue laser has been proposed. For example, Patent Documents 1 and 2 use a cyanine dye in a recording layer in an optical information recording medium for recording information by irradiating a short wavelength laser beam as in the Blu-ray optical recording disk. It has been proposed. Further, Patent Document 3 proposes that the physical property value of a recording dye is defined in an optical information recording medium compatible with a blue laser.
WO01 / 044374 JP 2001-232945 A JP 2007-26541 A

  The aforementioned Blu-ray disc generally has a narrower track pitch than a conventional write-once optical disc. Further, a conventional additional note that a reflective layer and a recording layer are provided in this order on a substrate, and a relatively thin light-transmitting layer (generally called a cover layer) is bonded on the recording layer. It has a layer structure different from the type optical disc. Also, the recording laser light has a shorter wavelength. For this reason, there is a problem in that sufficient recording / reproducing characteristics cannot be obtained with a dye used as a conventional recording dye for a write once optical information recording medium such as a CD-R or a DVD-R. On the other hand, Patent Documents 1 and 2 propose using a cyanine dye as a recording layer dye in information recording by irradiation with a short wavelength laser beam. However, as a result of the study by the inventors of the present application, it has been found that the techniques described in Patent Documents 1 and 2 cannot always obtain sufficient recording characteristics in the optical information recording medium having the Blu-ray configuration.

  On the other hand, in Patent Document 3, in the Blu-ray method, the recording characteristics are improved by changing the shape of the recording layer after paying attention to irradiating the medium with laser light from a different direction from the conventional write-once optical disc. Has proposed. Specifically, in Patent Document 2, the recording layer thickness is thinner than the groove groove depth (the dye layer is contained in the groove groove recess) by adjusting the dye application concentration and the application condition of the dye solution. In an optical recording medium having a recording layer with a special form in which the dye film thickness of the part is almost zero, it is described that good recording characteristics can be obtained by defining the dye physical property values. However, the method for forming a special recording layer described in Patent Document 2 is different from the method for forming a recording layer in a conventional CD-R, DVD-R, etc., and is difficult to manufacture.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an optical information recording medium having a Blu-ray disc configuration, which can exhibit good recording characteristics during recording by irradiation with a short wavelength laser beam and is easy to manufacture. There is to do.

  As a result of intensive studies to achieve the above object, the present inventors have used a polymethine dye having high thermal decomposability as a recording layer dye, and an adhesive layer for bonding the barrier layer and the cover layer together. By adopting a flexible layer composed of an ultraviolet curable resin, good recording characteristics can be obtained during recording by irradiation with a short wavelength laser beam without significantly changing the medium configuration as in the technique described in Patent Document 3. The present inventors have found that an optical information recording medium having a Blu-ray disc configuration that can be exhibited can be obtained, and have completed the present invention.

［一般式（Ｉ）中、Ｘ¹およびＸ²は、各々独立に、酸素原子、硫黄原子またはＮ−Ｒを表し、Ｒはアルキル基、アリール基、または複素環基を表し、Ｚａ¹およびＺａ²は、各々独立に、５員または６員の複素環を完成するために必要な原子群を表し、Ｌ¹、Ｌ²およびＬ³は、各々独立に、置換または無置換のメチン基を表し（但し、Ｌ¹〜Ｌ³上に置換基がある場合には互いに連結して環を形成してもよい）、ｊは、０または１を表し、Ｍ₁は電荷均衡対イオンを表し、ｍ１は分子の電荷を中和するために必要な０以上１０以下の数を表す。]
[２]ランド上の記録層の厚さとグルーブ上の記録層との厚さの比[（ランド上の記録層の厚さ）／（グルーブ上の記録層の厚さ）]が０．１〜１の範囲である[１]に記載の光記録情報媒体。
[３]一般式（Ｉ）で表される化合物は、下記一般式(II-1)または下記一般式(II-2)で表される化合物である[１]または[２]に記載の光情報記録媒体。

［一般式（ＩＩ−１）および（ＩＩ−２）中、Ｚｂは、インドレニン核、ベンゾインドレニン核、ベンゾイミダゾール核、ベンゾオキサゾール核またはベンゾチアゾール核を形成するために必要な原子群を表し、Ｘａは、酸素原子、硫黄原子、Ｃ（Ｒ₃）（Ｒ₄）またはＮ−Ｒ₅を表し、Ｒ₁、Ｒ₂、Ｒ₃、Ｒ₄およびＲ₅は、各々独立に、アルキル基またはアリール基を表し、Ｌ₄は、置換または無置換のメチン基を表す。Ｍ₁およびｍ１は、前記一般式（I）における定義と同義である。］
[４]一般式（I）で表される化合物は、下記一般式（III）で表される化合物である[１]または[２]に記載の光情報記録媒体。

［一般式（ＩＩＩ）中、ＸｂおよびＸｃは、各々独立に、酸素原子、硫黄原子、またはＮ−Ｒ₁₄を表し、Ｒ₆、Ｒ₇、Ｒ₈、Ｒ₉、Ｒ₁₀、Ｒ₁₁、Ｒ₁₂、Ｒ₁₃およびＲ₁₄は、各々独立に、水素原子、アルキル基またはアリール基を表し、Ｌ₅、Ｌ₆およびＬ₇は各々独立に置換または無置換のメチン基を表す。但し、Ｌ₅〜Ｌ₇上に置換基がある場合には、これらの置換基は互いに連結して環を形成してもよい。ｋは０または１を表す。Ｍ₁およびｍ１は、前記一般式(I-1)における定義と同義である。］
[５]前記紫外線硬化型組成物は、紫外線硬化型組成物１００質量部に対し、単官能（メタ）アクリレートを２０〜９９質量部、および多官能（メタ）アクリレートを１〜８０質量部含む[１]〜[４]のいずれかに記載の光情報記録媒体。
[６]波長３９０〜４４０ｎｍのレーザー光を照射することにより情報を記録するために使用される[１]〜[５]のいずれかに記載の光情報記録媒体。
[７][１]〜[５]のいずれかに記載の光情報記録媒体へ、波長３９０〜４４０ｎｍのレーザー光を照射することにより、光情報記録媒体の記録層へ情報を記録する情報記録方法。 That is, the above object was achieved by the following means.
[1] Optical information recording having a reflective layer, a recording layer, a barrier layer, and a cover layer in this order on the surface of a substrate having a plurality of grooves and pregrooves formed between adjacent grooves on the surface. A medium,
The track pitch of the pregroove is in the range of 50 to 500 nm,
The recording layer has a thickness in the range of 1 to 100 nm on the land and in the range of 5 to 150 nm on the groove.
The recording layer contains a thermally decomposable compound represented by the following general formula (I) and having a mass reduction rate of 10% or more in the main weight loss process in thermal mass spectrometry,
An optical information recording medium comprising a layer having a glass transition temperature of 25 ° C. or lower formed by subjecting an ultraviolet curable composition to a curing treatment between the barrier layer and the cover layer.

[In General Formula (I), X ¹ and X ² each independently represents an oxygen atom, a sulfur atom or N—R, R represents an alkyl group, an aryl group, or a heterocyclic group, and Za ¹ and Za ² each independently represents a group of atoms necessary to complete a 5- or 6-membered heterocyclic ring, and L ¹ , L ² and L ³ each independently represents a substituted or unsubstituted methine group. (However, when there is a substituent on L ^{1 to} L ³ , they may be linked to each other to form a ring), j represents 0 or 1, M ₁ represents a charge balanced counter ion, m 1 Represents a number from 0 to 10 which is necessary for neutralizing the charge of the molecule. ]
[2] Ratio of thickness of recording layer on land to recording layer on groove [(thickness of recording layer on land) / (thickness of recording layer on groove)] is 0.1 to The optical recording information medium according to [1], which is in the range of 1.
[3] The compound represented by the general formula (I) is a compound represented by the following general formula (II-1) or the following general formula (II-2): Information recording medium.

[In the general formulas (II-1) and (II-2), Zb represents an atomic group necessary for forming an indolenine nucleus, a benzoindolenine nucleus, a benzimidazole nucleus, a benzoxazole nucleus, or a benzothiazole nucleus. , Xa represents an oxygen atom, a sulfur atom, C (R ₃ ) (R ₄ ) or N—R ₅ , and R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently an alkyl group or Represents an aryl group, and L ₄ represents a substituted or unsubstituted methine group. M ₁ and m 1 have the same definition as in general formula (I). ]
[4] The optical information recording medium according to [1] or [2], wherein the compound represented by the general formula (I) is a compound represented by the following general formula (III).

[In General Formula (III), Xb and Xc each independently represent an oxygen atom, a sulfur atom, or N—R ₁₄ , and R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ each independently represents a hydrogen atom, an alkyl group or an aryl group, and L ₅ , L ₆ and L ₇ each independently represents a substituted or unsubstituted methine group. However, when there are substituents on L _{5 to} L ₇ , these substituents may be linked to each other to form a ring. k represents 0 or 1; M ₁ and m 1 have the same definition as in the general formula (I-1). ]
[5] The ultraviolet curable composition contains 20 to 99 parts by mass of monofunctional (meth) acrylate and 1 to 80 parts by mass of polyfunctional (meth) acrylate with respect to 100 parts by mass of the ultraviolet curable composition. The optical information recording medium according to any one of 1] to [4].
[6] The optical information recording medium according to any one of [1] to [5], which is used for recording information by irradiating a laser beam having a wavelength of 390 to 440 nm.
[7] An information recording method for recording information on a recording layer of an optical information recording medium by irradiating the optical information recording medium according to any one of [1] to [5] with laser light having a wavelength of 390 to 440 nm .

  According to the present invention, an optical information recording medium excellent in recording characteristics in a short wavelength region can be provided at low cost.

[Optical information recording medium]
The optical information recording medium of the present invention comprises a reflective layer, a recording layer, a barrier layer, and a cover layer on a surface of a substrate having a plurality of grooves and pregrooves formed between adjacent grooves on the surface. In this order. The track pitch of the pregroove is in the range of 50 to 500 nm, and the thickness of the recording layer is in the range of 1 to 100 nm on the land and in the range of 5 to 150 nm on the groove. In the present invention, in the optical information recording medium of the Blu-ray disc configuration,
(1) As a recording layer dye, a compound having a thermal decomposability represented by the following general formula (I) and having a mass reduction rate of 10% or more in the main weight loss process in thermal mass spectrometry,
(2) providing a layer having a glass transition temperature of 25 ° C. or lower formed by subjecting the ultraviolet curable composition to a curing treatment between the barrier layer and the cover layer;
Thus, excellent recording characteristics can be obtained.
The present inventors infer the reason why excellent recording characteristics can be obtained by this combination as follows.

When the recording layer containing the compound represented by the general formula (I) having the above thermal decomposability is irradiated with laser light, the dye absorbs the laser light and generates heat, and the heat causes the dye skeleton or its substituent to be thermally decomposed. It is considered that gas is generated and voids are formed in the pits. In the recording layer containing the above compound, the refractive index of the portion not irradiated with laser light is generally about 1.6 to 1.9, whereas the refractive index of the portion where voids are formed by laser light irradiation is about 1. 0, which is significantly different from the refractive index of the unirradiated part. Thereby, it is considered that a large refractive index difference can be realized, and the recording characteristics can be improved. Among the compounds represented by the general formula (I), a compound having a thermal decomposability having a mass reduction rate of 10% or more in the main weight loss process in the thermal mass spectrometry can satisfactorily form the voids. It is considered possible.
However, when the gap is formed in the recording layer by laser light irradiation as described above, the formation of the gap usually involves the deformation of the recording layer. It becomes difficult to obtain sufficient recording characteristics. For example, in an optical information recording medium having a light reflecting layer, a recording layer, a barrier layer, an adhesive layer, and a cover layer in this order on a substrate, the substrate and the light reflecting layer are generally more rigid than the adhesive layer and the barrier layer. high. Therefore, when the gap is formed, the recording layer pushes up the barrier layer, and when the adhesive layer located between the barrier layer and the cover layer is moderately flexible, the adhesive layer causes a concave deformation. As described above, when the adhesive layer located between the barrier layer and the cover layer is easily deformed, the formation of pits can be satisfactorily performed without preventing the formation of voids in the recording layer. In the optical information recording medium of the present invention, since the adhesive layer is flexible with a glass transition temperature of 25 ° C. or less and can be easily deformed with the formation of the voids, the voids can be formed satisfactorily.
The recording layer of the optical information recording medium of the present invention can be formed by the same method as the recording layer forming method in conventional CD-R, DVD-R and the like. In addition, by forming the recording layer from the ultraviolet curable composition, the apparatus for bonding with the cover layer can be simplified, and the bonding time can be shortened, so that low-cost manufacturing is possible.
As described above, according to the present invention, an optical information recording medium having good recording characteristics and excellent productivity can be obtained.

  A specific example of the optical information recording medium of the present invention is shown in FIG. A first optical information recording medium 10A shown in FIG. 2 includes a first light reflecting layer 18, a first write-once recording layer 14, a barrier layer 20, an adhesive layer 22, and a cover layer 16 on a first substrate 12. And in this order. Hereinafter, the materials constituting the substrate and other layers used in the optical information recording medium of the present invention will be described in order.

Substrate As the substrate used in the present invention, various materials used as substrate materials for conventional optical information recording media can be arbitrarily selected and used. As the substrate, a transparent disk-shaped substrate is preferably used.
Specifically, glass; acrylic resin such as polycarbonate and polymethyl methacrylate; vinyl chloride resin such as polyvinyl chloride and vinyl chloride copolymer; epoxy resin; amorphous polyolefin; polyester; metal such as aluminum; These may be used together if desired.
Among the materials, thermoplastic resins such as amorphous polyolefin and polycarbonate are preferable, and polycarbonate is particularly preferable from the viewpoints of moisture resistance, dimensional stability, and low price. When these resins are used, the substrate can be manufactured by injection molding.
The thickness of the substrate is generally in the range of 0.7 to 2 mm, preferably in the range of 0.9 to 1.6 mm, and more preferably 1.0 to 1.3 mm.
An undercoat layer can also be formed on the surface of the substrate on the side where the light reflecting layer, which will be described later, is provided for the purpose of improving flatness and adhesion.

  On the surface of the substrate on which the recording layer is formed, pregrooves (guide grooves) composed of a plurality of grooves and lands located between adjacent grooves are formed. This pre-groove is provided to achieve a higher recording density than CD-R and DVD-R. For example, the optical information recording medium of the present invention is used as a medium corresponding to a blue-violet laser. It is suitable for use.

  The track pitch of the pregroove is in the range of 50 to 500 nm. The upper limit is preferably 420 nm or less, more preferably 370 nm or less, and further preferably 330 nm or less. Further, the lower limit is preferably 100 nm or more, more preferably 200 nm or more, and further preferably 260 nm or more. If the track pitch is 50 nm or more, the pregroove can be formed accurately, and the occurrence of crosstalk can be avoided. If the track pitch is 500 nm or less, high-density recording can be performed.

  The track pitch of the pregroove is preferably 100 nm or more and 420 nm or less, more preferably 200 nm or more and 370 nm or less, and further preferably 260 nm or more and 330 nm or less.

  The groove width (half width) of the pregroove is preferably in the range of 25 to 250 nm. The upper limit is preferably 240 nm or less, more preferably 230 nm or less, and still more preferably 220 nm or less. Further, the lower limit is preferably 50 nm or more, more preferably 80 nm or more, and further preferably 100 nm or more. If the groove width of the pregroove is 25 nm or more, the groove can be sufficiently transferred at the time of molding, and further, an increase in error rate at the time of recording can be suppressed. Furthermore, it is possible to avoid the occurrence of crosstalk due to the spread of pits formed during recording.

  The groove width (half width) of the pregroove is preferably 50 nm or more and 240 nm or less, more preferably 80 nm or more and 230 nm or less, and further preferably 100 nm or more and 220 nm or less.

  The groove depth of the pregroove is preferably in the range of 5 to 150 nm. The upper limit is preferably 85 nm or less, more preferably 80 nm or less, and even more preferably 75 nm or less. Further, the lower limit is preferably 10 nm or more, more preferably 20 nm or more, and further preferably 28 nm or more. If the groove depth of the pregroove is 5 nm or more, a sufficient recording modulation degree can be obtained, and if it is 150 nm or less, a high reflectance can be obtained.

  The groove depth of the pregroove is preferably 10 nm to 85 nm, more preferably 20 nm to 80 nm, and still more preferably 28 nm to 75 nm.

In addition, the groove inclination angle of the pregroove is preferably 80 ° or less, more preferably 75 ° or less, still more preferably 70 ° or less, and particularly preferably 65 ° or less. preferable. Further, the lower limit value is preferably 20 ° or more, more preferably 30 ° or more, and further preferably 40 ° or more.
If the groove inclination angle of the pregroove is 20 ° or more, a sufficient tracking error signal amplitude can be obtained, and if it is 80 ° or less, the moldability is good.

The reflective layer can be formed on the substrate by, for example, vacuum deposition, sputtering, or ion plating with a light reflective material having a high reflectance with respect to the laser beam.
The thickness of the light reflecting layer is generally in the range of 10 to 300 nm and preferably in the range of 20 to 200 nm.
The reflectance is preferably 70% or more.

  As a light reflective material having a high reflectance, Mg, Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Ru, Rh, Pd , Ir, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Si, Ge, Te, Pb, Po, Sn, Bi, and the like, and metal and semi-metal or stainless steel. These light reflecting materials may be used alone, or may be used in combination of two or more kinds or as an alloy. Among these, Cr, Ni, Pt, Cu, Ag, Au, Al, and stainless steel are preferable. Particularly preferred is Au, Ag, Al or an alloy thereof, and most preferred is Au, Ag or an alloy thereof.

Recording layer The optical information recording medium of the present invention is a compound (polymethine derivative) represented by the following general formula (I) and having a mass decomposability of 10% or more in the main weight loss process in thermal mass spectrometry (polymethine derivative). Containing. The said compound can implement | achieve a big refractive index difference in a short wavelength region, and can exhibit the outstanding recording characteristic by short wavelength laser beam irradiation by combining with the contact bonding layer mentioned later.

［一般式（Ｉ）中、Ｘ¹およびＸ²は、各々独立に、酸素原子、硫黄原子またはＮ−Ｒを表し、Ｒはアルキル基、アリール基、または複素環基を表し、Ｚａ¹およびＺａ²は、各々独立に、５員または６員の複素環を完成するために必要な原子群を表し、Ｌ¹、Ｌ²およびＬ³は、各々独立に、置換または無置換のメチン基を表し（但し、Ｌ¹〜Ｌ³上に置換基がある場合には互いに連結して環を形成してもよい）、ｊは、０または１を表し、Ｍ₁は電荷均衡対イオンを表し、ｍ１は分子の電荷を中和するために必要な０以上１０以下の数を表す。]

[In General Formula (I), X ¹ and X ² each independently represents an oxygen atom, a sulfur atom or N—R, R represents an alkyl group, an aryl group, or a heterocyclic group, and Za ¹ and Za ² each independently represents a group of atoms necessary to complete a 5- or 6-membered heterocyclic ring, and L ¹ , L ² and L ³ each independently represents a substituted or unsubstituted methine group. (However, when there is a substituent on L ^{1 to} L ³ , they may be linked to each other to form a ring), j represents 0 or 1, M ₁ represents a charge balanced counter ion, m 1 Represents a number from 0 to 10 which is necessary for neutralizing the charge of the molecule. ]

  In the present invention, in order to satisfactorily form voids in the recording layer and enhance the recording characteristics, among the compounds represented by the general formula (I), the mass reduction rate in the main weight loss process in the thermal mass spectrometry is A compound having a thermal decomposability of 10% or more is used. When the temperature of the compound is raised in a certain temperature range, mass loss due to thermal decomposition occurs. Depending on the type of compound, there are usually several temperature ranges (mass reduction process) that show a large mass loss. In the present invention, among several mass reduction processes (weight reduction processes), the one with the greatest degree of mass reduction is called the main weight reduction process. The mass reduction rate can be obtained by the following method.

  As shown in FIG. 1, the compound having a mass M0 is heated at 10 ° C./min in a nitrogen atmosphere. As the temperature rises, the mass decreases little by little along a straight line ab, and when reaching a certain temperature, a sudden mass decrease along a substantially straight line cd occurs. When the temperature is further increased, the rapid mass decrease ends, and the mass decrease substantially along the straight line ef occurs. Here, at the intersection of the straight line ab and the straight line cd, the temperature is T1 (° C.), and the residual mass ratio with respect to the initial mass M0 is m1 (%). Further, at the intersection of the straight line cd and the straight line ef, the temperature is T2 (° C.), and the residual mass ratio with respect to the initial mass M0 is m2 (%). That is, in the main weight loss process, the weight loss start temperature is T1, the weight loss end temperature is T2, and the mass reduction rate is represented by (m1-m2) (%).

The decrease in mass under the nitrogen atmosphere is considered to be due to the generation of gas based not on the oxidative decomposition but on the substituent decomposition or skeleton decomposition of the dye. Therefore, it is considered that the higher the mass reduction rate, the more gas is generated due to thermal decomposition, which is advantageous for void formation. It is considered that among the compounds represented by the general formula (I), when the recording layer contains a material having a mass reduction rate of 10% or more, the amount of gas generated by laser light irradiation is large and pits can be formed satisfactorily. Among the compounds represented by the general formula (I), those having a thermal decomposability with a mass reduction rate of 20% or more during thermal decomposition at 150 ° C. to 400 ° C. are more preferable, and thermal decomposition at 200 ° C. to 400 ° C. What has thermal decomposability whose mass reduction rate at the time is 25% or more is still more preferable. The thermal decomposability of the dye can be controlled by the type of substituent introduced into the dye skeleton.
Specifically, for example, Seiko Instruments Inc. Using EXSTAR6000, the mass reduction rate can be obtained by raising the temperature at 10 ° C./min in the range of 30 ° C. to 550 ° C. under a N ₂ air flow (flow rate 200 ml / min).

Furthermore, in order to improve sensitivity, it is preferable to use a compound having good thermal decomposability as the compound. As an index of thermal decomposability, the thermal decomposition temperature can be used. In the present invention, it is preferable to use a compound having a thermal decomposition temperature of 150 to 400 ° C., preferably 200 to 400 ° C., more preferably 200 to 380 ° C. In addition, the thermal decomposition temperature in this invention shall say the value calculated | required by TG / DTA measurement. Specifically, for example, Seiko Instruments Inc. Using EXSTAR6000 manufactured, the temperature was raised at 10 ° C / min in the range of 30 ° C to 550 ° C under an N ₂ stream (flow rate 200 ml / min), and the temperature at which the mass reduction rate reached 10% was the thermal decomposition temperature. Can be requested.

  Details of the general formula (I) will be described below.

［一般式（Ｉ）中、Ｘ¹およびＸ²は、各々独立に、酸素原子、硫黄原子またはＮ−Ｒを表し、Ｒはアルキル基、アリール基、または複素環基を表し、Ｚａ¹およびＺａ²は、各々独立に、５員または６員の複素環を完成するために必要な原子群を表し、Ｌ¹、Ｌ²およびＬ³は、各々独立に、置換または無置換のメチン基を表し（但し、Ｌ¹〜Ｌ³上に置換基がある場合には互いに連結して環を形成してもよい）、ｊは、０または１を表し、Ｍ₁は電荷均衡対イオンを表し、ｍ１は分子の電荷を中和するために必要な０以上１０以下の数を表す。]

[In General Formula (I), X ¹ and X ² each independently represents an oxygen atom, a sulfur atom or N—R, R represents an alkyl group, an aryl group, or a heterocyclic group, and Za ¹ and Za ² each independently represents a group of atoms necessary to complete a 5- or 6-membered heterocyclic ring, and L ¹ , L ² and L ³ each independently represents a substituted or unsubstituted methine group. (However, when there is a substituent on L ^{1 to} L ³ , they may be linked to each other to form a ring), j represents 0 or 1, M ₁ represents a charge balanced counter ion, m 1 Represents a number from 0 to 10 which is necessary for neutralizing the charge of the molecule. ]

In general formula (I), L ₁ , L ₂ and L ₃ each independently represents a substituted or unsubstituted methine group. When there are substituents on L ^{1 to} L ³ , they may be linked to each other to form a ring.

  When the substituent that the methine group may have is V, the substituent represented by V is not particularly limited. For example, a halogen atom (for example, chlorine, bromine, iodine, fluorine), a mercapto group, a cyano group, a carboxyl group , Phosphoric acid group, sulfo group, hydroxy group, carbamoyl group having 1 to 10 carbon atoms, preferably 2 to 8 carbon atoms, more preferably 2 to 5 carbon atoms (for example, methylcarbamoyl group, ethylcarbamoyl group, morpholinocarbonyl group) A sulfamoyl group having 0 to 10 carbon atoms, preferably 2 to 8 carbon atoms, more preferably 2 to 5 carbon atoms (for example, a methylsulfamoyl group, an ethylsulfamoyl group, a piperidinosulfonyl group), a nitro group, An alkoxy group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms (for example, methoxy group, ethoxy group) 2-methoxyethoxy group, 2-phenylethoxy group), an aryloxy group having 6 to 20 carbon atoms, preferably 6 to 12 carbon atoms, more preferably 6 to 10 carbon atoms (for example, a phenoxy group, a p-methylphenoxy group, p-chlorophenoxy group, naphthoxy group), C1-C20, preferably C2-C12, more preferably C2-C8 acyl group (for example, acetyl group, benzoyl group, trichloroacetyl group), carbon number 1-20, preferably C2-C12, more preferably C2-C8 acyloxy group (for example, acetyloxy group, benzoyloxy group), C1-C20, preferably C2-C12, more preferably Is an acylamino group having 2 to 8 carbon atoms (for example, acetylamino group), 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably Is a sulfonyl group having 1 to 8 carbon atoms (for example, methanesulfonyl group, ethanesulfonyl group, benzenesulfonyl group, etc.), 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably a sulfinyl group having 1 to 8 carbon atoms ( For example, methanesulfinyl group, benzenesulfinyl group), sulfonylamino group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms (for example, methanesulfonylamino group, ethanesulfonylamino group, benzenesulfonylamino group) Group), an amino group, a substituted amino group having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms (for example, a methylamino group, a dimethylamino group, a benzylamino group, an anilino group, Diphenylamino group), 0-15 carbon atoms, preferably 3-10 carbon atoms, more preferred Or a C3-C6 ammonium group (for example, trimethylammonium group or triethylammonium group), C0-C15, preferably C1-C10, more preferably C1-C6 hydrazino group (e.g. trimethylhydra). Dino group), a ureido group having 1 to 15 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms (for example, a ureido group, N, N-dimethylureido group), 1 to 15 carbon atoms, preferably Is an imide group having 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms (for example, a succinimide group), 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, and more preferably an alkyl or arylthio having 1 to 8 carbon atoms. Group (for example, methylthio group, ethylthio group, carboxyethylthio group, sulfobutylthio group, phenylthio group, etc.) 0, preferably an alkoxycarbonyl group having 2 to 12 carbon atoms, more preferably 2 to 8 carbon atoms (for example, methoxycarbonyl group, ethoxycarbonyl group, benzyloxycarbonyl group), 6 to 20 carbon atoms, preferably 6 to 6 carbon atoms 12, more preferably an aryloxycarbonyl group having 6 to 8 carbon atoms (for example, phenoxycarbonyl group), an unsubstituted alkyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms ( For example, a methyl group, an ethyl group, a propyl group, a butyl group), a substituted alkyl group having 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, and more preferably 1 to 5 carbon atoms (hydroxymethyl group, trifluoromethyl group). Benzyl group, carboxyethyl group, ethoxycarbonylmethyl group, acetylaminomethyl group, and here An unsaturated hydrocarbon group having 2 to 18 carbon atoms, more preferably 3 to 10 carbon atoms, particularly preferably 3 to 5 carbon atoms (for example, a vinyl group, an ethynyl group, a 1-cyclohexenyl group, a benzylidine group, a benzylidene group). Group) is also included in the substituted alkyl group. ), A substituted or unsubstituted aryl group having 6 to 20 carbon atoms, preferably 6 to 15 carbon atoms, more preferably 6 to 10 carbon atoms (for example, phenyl group, naphthyl group, p-carboxyphenyl group, p-nitrophenyl). Group, 3,5-dichlorophenyl group, p-cyanophenyl group, m-fluorophenyl group, p-tolyl group), C1-20, preferably C2-10, and more preferably C4-6. Examples thereof include a heterocyclic group which may be substituted (for example, pyridyl group, 5-methylpyridyl group, thienyl group, furyl group, morpholino group, tetrahydrofurfuryl group).

Preferred examples of the substituent include the above-described alkyl group, aryl group, alkoxy group, halogen atom, acyl group, cyano group, sulfonyl group, and benzene ring condensation, and more preferable alkyl group, aryl group, halogen atom, acyl group. And a sulfonyl group. L _{1 to} L ₃ are preferably unsubstituted methine groups.

  j is 0 or 1, and when j is 1, the methine group is repeated but need not be identical.

X ¹ and X ² each independently represents an oxygen atom, a sulfur atom or N—R, and R represents an alkyl group, an aryl group or a heterocyclic group. X ¹ and X ² may be the same or different, but are preferably the same.

As the alkyl group, for example, an unsubstituted alkyl group having 1 to 18 carbon atoms, preferably 1 to 7 carbon atoms, particularly preferably 1 to 4 carbon atoms (for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, A hexyl group, an octyl group, a dodecyl group, an octadecyl group), a substituted alkyl group having 1 to 18, preferably 1 to 7, and particularly preferably 1 to 4 carbon atoms {for example, V mentioned as a substituent such as L ₁ described above Examples include substituted alkyl groups. Preferably, an aralkyl group (for example, benzyl group, 2-phenylethyl group), an unsaturated hydrocarbon group (for example, allyl group), a hydroxyalkyl group (for example, 2-hydroxyethyl group, 3-hydroxypropyl group), a carboxyalkyl group ( For example, 2-carboxyethyl group, 3-carboxypropyl group, 4-carboxybutyl group, carboxymethyl group), alkoxyalkyl group (for example, 2-methoxyethyl group, 2- (2-methoxyethoxy) ethyl group), aryl Roxyalkyl groups (for example, 2-phenoxyethyl group, 2- (1-naphthoxy) ethyl group), alkoxycarbonylalkyl groups (for example, ethoxycarbonylmethyl group, 2-benzyloxycarbonylethyl group), aryloxycarbonylalkyl groups (for example, 3 -Phenoxycarbonylpropi Group), an acyloxyalkyl group (for example, 2-acetyloxyethyl group), an acylalkyl group (for example, 2-acetylethyl group), a carbamoylalkyl group (for example, 2-morpholinocarbonylethyl group), a sulfamoylalkyl group (for example, N, N-dimethylcarbamoylmethyl group), sulfoalkyl group (for example, 2-sulfoethyl group, 3-sulfopropyl group, 3-sulfobutyl group, 4-sulfobutyl group, 2- [3-sulfopropoxy] ethyl group, 2-hydroxy- 3-sulfopropyl group, 3-sulfopropoxyethoxyethyl group), sulfoalkenyl group (for example, sulfopropenyl group), sulfatoalkyl group (for example, 2-sulfatoethyl group, 3-sulfatopropyl group, 4-sulfopropyl group) Fat-butyl group), a heterocyclic-substituted alkyl group (for example, 2- Pyrrolidin-2-one-1-yl) ethyl group, tetrahydrofurfuryl group), alkylsulfonylcarbamoyl methyl group (e.g. methanesulfonyl carbamoylmethyl methyl group)} and the like.

As the aryl group, for example, an unsubstituted aryl group having 6 to 20 carbon atoms, preferably 6 to 10 carbon atoms, more preferably 6 to 8 carbon atoms (for example, phenyl group, 1-naphthyl group), 6 to 20 carbon atoms, Preferably, it is a substituted aryl group having 6 to 10 carbon atoms, more preferably 6 to 8 carbon atoms (for example, an aryl group substituted with V mentioned as a substituent such as L ¹ described above. Specifically, p-methoxy is mentioned. A phenyl group, a p-methylphenyl group, a p-chlorophenyl group, etc.).

Examples of the heterocyclic group include unsubstituted heterocyclic groups having 1 to 20 carbon atoms, preferably 3 to 10 carbon atoms, and more preferably 4 to 8 carbon atoms (for example, 2-furyl group, 2-thienyl group, 2-pyridyl group). Group, 3-pyrazolyl group, 3-isoxazolyl group, 3-isothiazolyl group, 2-imidazolyl group, 2-oxazolyl group, 2-thiazolyl group, 2-pyridazyl group, 2-pyrimidyl group, 3-pyrazyl group, 2- ( 1,3,5-triazolyl) group, 3- (1,2,4-triazolyl) group, 5-tetrazolyl group), C1-20, preferably C3-10, more preferably C4 8 substituted heterocyclic groups (for example, a heterocyclic group substituted by V mentioned as a substituent such as L ¹ described above, specifically, 5-methyl-2-thienyl group, 4-methoxy-2-pyridyl) Group It is.) And the like.

Za ¹ and Za ² each independently represents an atomic group necessary for completing a 5-membered or 6-membered heterocyclic ring. Za ¹ and Za ² may be the same or different, but are preferably the same.
Examples of the 5-membered or 6-membered heterocyclic ring (nucleus) containing Za ¹ include thiazole nucleus, benzothiazole nucleus, naphthothiazole nucleus, thiazoline nucleus, oxazole nucleus, benzoxazole nucleus, naphthoxazole nucleus, oxazoline nucleus, and selenazole nucleus. , Benzoselenazole nucleus, naphthoselenazole nucleus, selenazoline nucleus, tellurazole nucleus, benzotelrazole nucleus, naphthotelrazole nucleus, tellurazoline nucleus, imidazole nucleus, benzimidazole nucleus, naphthimidazole nucleus, pyridine nucleus, quinoline nucleus, isoquinoline nucleus, Imidazo [4,5-b] quinoxaline nucleus, oxadiazole nucleus, thiadiazole nucleus, tetrazole nucleus, pyrimidine nucleus, pyrrole nucleus, indolenine nucleus, benzoindolenine nucleus, 1,3-dioxolane nucleus, and 1,3-dithiolane Nuclear It can be mentioned. Among these, thiazole nucleus, thiazoline nucleus, benzothiazole nucleus, oxazole nucleus, oxazoline nucleus, benzoxazole nucleus, imidazole nucleus, benzimidazole nucleus, naphthimidazole nucleus, quinoline nucleus, isoquinoline nucleus, imidazo [4,5-b] A quinoxaline nucleus, thiadiazole nucleus, tetrazole nucleus, pyrimidine nucleus, pyrrole nucleus, indolenine nucleus, benzoindolenine nucleus, 1,3-dioxolane nucleus, and 1,3-dithiolane nucleus are preferred. These rings may be further condensed with a benzene ring, a dioxolane ring, or a naphthoquinone ring.

  The 5-membered or 6-membered nitrogen-containing heterocyclic ring may have a substituent. Examples of preferred substituents (atoms) include halogen atoms, substituted or unsubstituted alkyl groups, aryl groups, alkoxy groups, and alkoxycarbonyl groups. As the halogen atom, a chlorine atom is preferable. The alkyl group is preferably a linear alkyl group having 1 to 6 carbon atoms. Examples of the substituent for the alkyl group include an alkoxy group (eg, methoxy group) and an alkylthio group (eg, methylthio group). As the aryl group, a phenyl group is preferable. As the alkoxy group, a methoxy group is preferable. As the alkoxycarbonyl group, a methoxycarbonyl group is preferable. Particularly preferred examples of the substituent are a halogen atom, an unsubstituted alkyl group, an alkoxy group, and an alkoxycarbonyl group.

M ₁ represents a charge-balanced counter ion and is included in the formula to indicate the presence of a cation or an anion when needed to neutralize the ionic charge of the dye. Typical cations include inorganic cations such as hydrogen ions (H ⁺ ), alkali metal ions (eg, sodium ions, potassium ions, lithium ions), alkaline earth metal ions (eg, calcium ions), ammonium ions (eg, Organic ions such as ammonium ion, tetraalkylammonium ion, pyridinium ion, ethylpyridinium ion). The anion may be either an inorganic anion or an organic anion, such as a halogen anion (eg, fluorine ion, chlorine ion, iodine ion), a substituted aryl sulfonate ion (eg, p-toluenesulfonate ion, p-chloro). Benzene sulfonate ion), aryl disulfonate ion (for example, 1,3-benzene sulfonate ion, 1,5-naphthalene disulfonate ion, 2,6-naphthalene disulfonate ion), alkyl sulfate ion (for example, methyl sulfate ion), Examples thereof include sulfate ion, thiocyanate ion, perchlorate ion, tetrafluoroborate ion, picrate ion, acetate ion, and trifluoromethanesulfonate ion. Furthermore, you may use the ionic polymer or another pigment | dye which has a charge opposite to a pigment | dye. In the present invention, the sulfo group is expressed as SO ₃ ⁻ , but it can also be expressed as SO ₃ H when it has a hydrogen ion as a counter ion. m1 represents a number from 0 to 10 necessary for neutralizing the charge of the molecule, and is 0 when a salt is formed in the molecule.

  The compound represented by the general formula (I) is preferably a compound represented by the following general formula (II-1), the following general formula (II-2), or the following general formula (III).

In the general formulas (II-1) and (II-2), Zb represents an atomic group necessary for forming an indolenine nucleus, a benzoindolenine nucleus, a benzimidazole nucleus, a benzoxazole nucleus or a benzothiazole nucleus, Xa represents an oxygen atom, a sulfur atom, C (R ₃ ) (R ₄ ) or N—R ₅ , and R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently an alkyl group or aryl And L ₄ represents a substituted or unsubstituted methine group. M ₁ and m1 have the same definition as in the general formula (I-1), and their preferred ranges are also the same.

  The indolenine nucleus, benzoindolenine nucleus, benzimidazole nucleus, benzoxazole nucleus or benzothiazole nucleus containing Zb may have a substituent. Examples of the substituent (which may be an atom) include the examples of the substituent on the 5-membered or 6-membered heterocyclic ring described above, and the preferred ranges thereof are also the same.

R ₁ and R ₂ represent an alkyl group or an aryl group, and details thereof are as described above for R in the general formula (I-1).

R ₃ , R ₄ and R ₅ represent an alkyl group or an aryl group, preferably an alkyl group, more preferably a linear or branched chain having 1 to 18 carbon atoms which may have a substituent. Or a cyclic alkyl group. The alkyl group represented by R ₃ , R ₄ and R ₅ is particularly preferably a linear unsubstituted alkyl group having 1 to 6 carbon atoms (for example, a methyl group or an ethyl group).

In the general formula (III), Xb and Xc each independently represent an oxygen atom, a sulfur atom, or N—R ₁₄ , and R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ each independently represents a hydrogen atom, an alkyl group or an aryl group, and L ₅ , L ₆ and L ₇ each independently represents a substituted or unsubstituted methine group. However, when there are substituents on L _{5 to} L ₇ , these substituents may be linked to each other to form a ring. k represents 0 or 1; M ₁ and m1 are synonymous with the definitions in the general formula (I-1), and their preferred ranges are also the same.

Xb and Xc are each an oxygen atom, a sulfur atom, or N—R ₁₄ , or one is an oxygen atom and the other is N—R ₁₄ , or one is a sulfur atom and the other is N—R _14. It is preferable to become a combination of R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom or a substituent. A good linear, branched or cyclic alkyl group having 1 to 18 carbon atoms. The alkyl groups represented by R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are each a linear unsubstituted alkyl having 1 to 6 carbon atoms. A group (for example, a methyl group or an ethyl group) is particularly preferable.

In the general formula (III), L ₅ , L ₆ and L ₇ each independently represent a substituted or unsubstituted methine group, the details of which are represented by L ₁ , L ₂ and the general formula (I-1) As described for L ₃ .

  Preferred specific examples of the compound represented by the general formula (I) (including the compound represented by the general formula (II-1), the general formula (II-2), or (III)) are shown below.

  Examples of the coloring compound include, for example, “The Cyanin Soybean and Related Compounds 5 (Interscience Publishers, NY 1964)” p. 55;・ "Polymethine soy", Saint-Clement Aurizuki University Press, Sofia (Nikolai Tyutyulkov, Jurgen Fabian, Achim Ulehlhorn, Fritz Dietz, Alia Tadjer) St. Kliment Ohridski University Press, Sophia, pp. 23-38; DMSturmer, "Heterocyclic Compounds-Special Topics in Heterocyclic Compounds-Special Topics in repeating chemistry) "Chapter 18, Section 14, pp. 482-515, John Wiley & Sons, New York, London, (1977);" Rods Chemistry of Carbon Compounds. " (Rodd's Chemistry of Carbon Compounds) ”(2nd.Ed.vol.IV, part B, published in 1977), Chapter 15, pages 369-422, (2nd.Ed.vol.IV, part B, published in 1985) , Chapter pp. 267-296, Elsvier Science Public Company Inc., New York, and the like.

  In order to introduce a polyvalent anion as a counter ion, first, a dye having a monovalent counter ion is dissolved in a suitable solvent, and a solution of a polyvalent acid or a salt thereof is added thereto. A method of adding a solvent that hardly dissolves the dye and precipitating a dye crystal having a multivalent ion as a counter ion is the simplest and suitable for a large amount of synthesis. Other methods include a method of exchanging counter ions using an ion exchange resin.

  The polymethine dyes described above may be used alone or in combination of two or more. Moreover, you may use together with the said pigment | dye compound and the pigment | dye compound for optical information recording media other than these. Examples of dye compounds that can be used in combination include cyanine dyes other than the polymethine dyes, oxonol dyes, azo metal complexes, phthalocyanine dyes, pyrylium dyes, thiopyrylium dyes, azurenium dyes, squarylium dyes, and naphthoquinones. And dyes based on triphenylmethane and triarylmethane. Preferred are azo dyes, azo metal dyes and phthalocyanine dyes, and more preferred are azo metal dyes and phthalocyanine dyes.

  The usage-amount of the pigment | dye for recording layers is the range of 1-100 mass% with respect to the total mass of a recording layer, for example, Preferably it is 50-100 mass%, More preferably, it is the range of 75-100 mass%. When the polymethine dye and another dye are used in combination as the recording layer dye, the ratio of the polymethine dye to the total amount of the dye is preferably 1% by mass or more, more preferably 10 to 100% by mass, and 50 It is especially preferable that it is -100 mass%.

Next, formation of the recording layer will be described.
The recording layer is prepared by dissolving the dye together with a binder or the like in an appropriate solvent without using a binder, and then coating this coating liquid on a reflective layer described later to form a coating film. After forming, it can be formed by drying. Here, the write-once recording layer may be a single layer or a multilayer. A recording layer having a multilayer structure can be formed by performing the step of applying the coating solution a plurality of times.
The concentration of the dye in the coating solution is generally in the range of 0.01 to 15% by mass, preferably in the range of 0.1 to 10% by mass, more preferably in the range of 0.5 to 5% by mass, most preferably. It is the range of 0.5-3 mass%.

Solvents used for preparing the coating solution include, for example, esters such as butyl acetate, ethyl lactate and cellosolve acetate; ketones such as methyl ethyl ketone, cyclohexanone and methyl isobutyl ketone; chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane and chloroform. Amides such as dimethylformamide; hydrocarbons such as methylcyclohexane; ethers such as tetrahydrofuran, ethyl ether and dioxane; alcohols such as ethanol, n-propanol, isopropanol and n-butanol diacetone alcohol; 2,2,3,3- Fluorinated solvents such as tetrafluoro-1-propanol; glycol agents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether And the like can be given; le compound.
Solvents can be used alone or in combination of two or more in consideration of the solubility of the dye used. In the coating solution, various additives such as a binder, an antioxidant, a UV absorber, a plasticizer, and a lubricant may be added according to the purpose.

Examples of the coating method include a spray method, a spin coating method, a dip method, a roll coating method, a blade coating method, a doctor roll method, and a screen printing method.
At the time of application, the temperature of the coating solution is preferably in the range of 23 to 50 ° C, more preferably in the range of 24 to 40 ° C, and particularly preferably in the range of 23 to 38 ° C.

The thickness of the write-once recording layer is in the range of 1 to 100 nm on the land and in the range of 5 to 150 nm on the groove. The thickness on the land (the convex portion in the substrate) is preferably 70 nm or less, more preferably 50 nm or less, and still more preferably 30 nm or less. The lower limit is preferably 5 nm or more, and more preferably 15 nm or more.
Further, the thickness of the write-once recording layer is preferably 100 nm or less, more preferably 50 nm or less on the groove (the concave portion in the substrate). The lower limit is preferably 10 nm or more, and more preferably 20 nm or more.
Further, the ratio of the thickness of the write-once recording layer on the land and the thickness of the write-once recording layer on the groove [(thickness of recording layer on land) / (thickness of recording layer on groove)] is 0. Is preferably 0.13 or more, more preferably 0.13 or more, further preferably 0.15 or more, and particularly preferably 0.17 or more. The upper limit is preferably 1 or less, more preferably 0.9 or less, still more preferably 0.85 or less, and particularly preferably 0.8 or less.

  Further, the recording layer can contain various anti-fading agents in order to improve the light resistance of the recording layer. Examples of the antifading agent include organic oxidants and singlet oxygen quenchers. As the organic oxidizing agent used as an anti-fading agent, compounds described in JP-A-10-151861 are preferable. As the singlet oxygen quencher, those described in publications such as known patent specifications can be used. Specific examples thereof include JP-A Nos. 58-175893, 59-81194, 60-18387, 60-19586, 60-19586, 60-35054, 60-36190, 60-36191, 60-44554, 60-44555, 60-44389, 60-44390, 60-54892, 60-47069, 63-209995, JP Listed in publications such as Nos. 4-25492, 1-38680, and 6-26028, German Patent No. 350399, and the Chemical Society of Japan, October 1992, page 1141 Can do. Examples of preferable singlet oxygen quenchers include compounds represented by the following general formula (A).

In the general formula (A), R ²¹ represents an alkyl group which may have a substituent, and Q ⁻ represents an anion.

In the general formula (A), R ²¹ is an optionally substituted alkyl group having 1 to 8 carbon atoms, and an unsubstituted alkyl group having 1 to 6 carbon atoms is preferable. Examples of the substituent of the alkyl group include halogen atoms (eg, F, Cl), alkoxy groups (eg, methoxy group, ethoxy group), alkylthio groups (eg, methylthio group, ethylthio group), acyl groups (eg, acetyl group, Propionyl group), acyloxy group (eg, acetoxy group, propionyloxy group), hydroxy group, alkoxycarbonyl group (eg, methoxycarbonyl group, ethoxycarbonyl group), alkenyl group (eg, vinyl group), aryl group (eg, phenyl) Group, naphthyl group). Among these, a halogen atom, an alkoxy group, an alkylthio group, and an alkoxycarbonyl group are preferable. Preferable examples of the anion of Q ⁻ include ClO ₄ ⁻ , AsF ₆ ⁻ , BF ₄ ⁻ , and SbF ₆ ⁻ .

  Examples of compounds represented by formula (A) (compound numbers A-1 to A-8) are shown in Table 1 below.

  The amount of the antifading agent such as the singlet oxygen quencher used is usually in the range of 0.1 to 50% by mass, preferably in the range of 0.5 to 45% by mass, more preferably relative to the amount of the dye. Is in the range of 3-40% by weight, particularly preferably in the range of 5-25% by weight.

Adhesive Layer The optical information recording medium of the present invention has a layer (adhesive layer) formed by subjecting the ultraviolet curable composition to a curing treatment between the barrier layer and the cover layer. The glass transition temperature of this adhesive layer is 25 ° C. or lower. If the glass transition temperature of the adhesive layer exceeds 25 ° C., the adhesive layer is not deformed well due to the formation of voids in the recording layer, and it becomes difficult to obtain sufficient recording characteristics. In order to obtain excellent recording characteristics, the glass transition temperature of the adhesive layer is preferably 0 ° C. or lower, more preferably −10 ° C. or lower. In terms of storage stability, the glass transition temperature of the adhesive layer is preferably −100 ° C. or higher. That is, the glass transition temperature of the adhesive layer used in the present invention is preferably in the range of 25 ° C to -100 ° C, more preferably 0 ° C to -100 ° C, and further preferably -10 ° C to -100 ° C. .
The glass transition temperature (Tg) in the present invention is a dynamic viscoelasticity measuring device (for example, DVA-200 manufactured by IT Measurement Control Co., Ltd.) with a frequency of 1 Hz, when measured in a tensile mode or a shear mode. It represents the maximum value of loss tangent (tan δ) determined by elastic behavior.
Moreover, as a glass transition temperature, the glass transition temperature calculated | required by differential scanning calorimetry (DSC) (henceforth "glass transition temperature (DSC)") with the glass transition temperature calculated | required from the said dynamic viscoelastic behavior. Is also known. The glass transition temperature of the adhesive layer used in the present invention is preferably 10 ° C. or less, more preferably −15 to −125 ° C., and −35 to −125 ° C. as the glass transition temperature (DSC). More preferably.
The glass transition temperature of the adhesive layer can be controlled by the formulation of the ultraviolet curable composition used for forming the adhesive layer, the type of the ultraviolet curable compound contained in the composition, the curing conditions, and the like.

  In the present invention, the storage elastic modulus can also be used as an indicator of the hardness of the adhesive layer, similarly to the glass transition temperature. The storage elastic modulus E ′ in the tensile mode of the adhesive layer is preferably 30 MPa or less, more preferably 15 MPa or less, and further preferably 10 MPa or less at 30 ° C. The storage elastic modulus of the adhesive layer is preferably 0.001 MPa or more from the viewpoint of storage stability. That is, the storage elastic modulus of the adhesive layer is preferably in the range of 30 MPa to 0.001 MPa, more preferably 15 MPa to 0.010 MPa, and still more preferably 10 MPa to 0.015 MPa. The storage elastic modulus G ′ of the adhesive layer according to the shear mode is preferably 10 MPa or less, more preferably 5 MPa or less, and further preferably 3.3 MPa or less at 30 ° C. The storage elastic modulus of the adhesive layer is preferably 0.00033 MPa or more from the viewpoint of storage stability. That is, the storage elastic modulus of the adhesive layer is preferably in the range of 10 MPa to 0.00033 MPa, more preferably 5 MPa to 0.0033 MPa, and still more preferably 3.3 MPa to 0.005 MPa. It is generally known that the relational expression E ′ = 3G ′ holds when there is no volume change upon deformation. The storage elastic modulus is obtained from a dynamic viscoelastic behavior obtained by measurement at a frequency of 1 Hz by a dynamic viscoelasticity measuring apparatus (for example, DVA-200 manufactured by IT Measurement Control Co., Ltd.), similarly to the glass transition temperature. Can do. Further, the loss tangent (tan δ) determined by the dynamic viscoelastic behavior is preferably in the range of 2.0 to 0.001 at 30 ° C., more preferably 1 when measured in a frequency of 1 Hz, tensile mode or shear mode. The range is from 0.5 to 0.002, and more preferably from 1.0 to 0.003.

The ultraviolet curable composition used for forming the ultraviolet curable composition recording layer is a coating liquid containing an ultraviolet curable compound and optionally various components described later.

［一般式（A）、（B）中、Ｒ¹は置換基を表す。］ As the ultraviolet curable compound, a polymerizable monomer component such as monofunctional (meth) acrylate or polyfunctional (meth) acrylate can be used. Each of these can be used alone or in combination of two or more. In the present invention, the acrylate of the following general formula (A) and the methacrylate of the following general formula (B) are collectively referred to as (meth) acrylate, and similarly, acrylic acid and methacrylic acid are combined (meth ) Called acrylic acid.

[In General Formulas (A) and (B), R ¹ represents a substituent. ]

Examples of the polymerizable monomer that can be used in the present invention include the following. As the monofunctional (meth) acrylate, for example, in the general formulas (A) and (B), the substituent R ¹ is methyl group, ethyl group, propyl group, butyl group, sec-butyl group, ter-butyl group, pentyl group, Hexyl, heptyl, 2-ethylhexyl, octyl, nonyl, dodecyl, hexadecyl, octadecyl, cyclohexyl, benzyl, methoxyethyl, butoxyethyl, phenoxyethyl, nonylphenoxyethyl, tetrahydro Furfuryl group, glycidyl group, 2-hydroxyethyl group, 2-hydroxypropyl group, 3-chloro-2-hydroxypropyl group, dimethylaminoethyl group, diethylaminoethyl group, nonylphenoxyethyltetrahydrofurfuryl group, caprolactone-modified tetrahydrofurfur Furyl group, isobornyl group (Meth) acrylate having a substituent such as dicyclopentanyl group, dicyclopentenyl group, dicyclopentenyloxyethyl group and the like, and (meth) acrylic acid.
Preferred substituents R ¹ include butyl group, pentyl group, hexyl group, heptyl group, 2-ethylhexyl group, octyl group, nonyl group, dodecyl group, and more preferred monomers are butyl acrylate, hexyl acrylate, 2- Examples include ethylhexyl acrylate, octyl acrylate, nonyl acrylate, and dodecyl methacrylate.

Examples of the polyfunctional (meth) acrylate include 1,3-butylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, and 1,6-hexane. Diacrylates such as diol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, tricyclodecane dimethanol, ethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, Di (meth) acrylate of tris (2-hydroxyethyl) isocyanurate, di (meth) acrylate of diol obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of neopentyl glycol, Di (meth) acrylate, trimethylolpropane tri (meth) acrylate of diol obtained by adding 2 mol of ethylene oxide or propylene oxide to 1 mol of Sphenol A, 3 mol or more of ethylene oxide or propylene per 1 mol of trimethylolpropane Diol or tri (meth) acrylate of triol obtained by adding oxide, di (meth) acrylate of diol obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of bisphenol A, tris (2-hydroxyethyl) ) Tri (meth) acrylate obtained by adding 3 mol or more of ethylene oxide or propylene oxide to 1 mol of isocyanurate tri (meth) acrylate and tris (2-hydroxyethyl) isocyanurate , Pentaerythritol tri- or tetra (meth) acrylate, tri- or tetra (meth) acrylate obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of pentaerythritol, poly (meth) acrylate of dipentaerythritol , Poly (meth) acrylate obtained by adding 6 mol or more of ethylene oxide or propylene oxide to 1 mol of dipentaerythritol, caprolactone-modified tris [(meth) acryloxyethyl] isocyanurate, alkyl-modified dipentaerythritol poly ( (Meth) acrylate, caprolactone-modified dipentaerythritol poly (meth) acrylate, hydroxypivalate neopentyl glycol diacrylate, caprolactone-modified hydro Shipibarin acid neopentyl glycol diacrylate, ethylene oxide-modified phosphoric acid (meth) acrylate, ethylene oxide-modified alkylated phosphoric acid (meth) acrylate.
Preferably, obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of bisphenol A, and adding 3 mol or more of ethylene oxide or propylene oxide to 1 mol of trimethylolpropane. Triol di- or tri (meth) acrylate, tri (meth) acrylate obtained by adding 3 mol or more of ethylene oxide or propylene oxide to 1 mol of tris (2-hydroxyethyl) isocyanurate, 4 mol of 1 mol of pentaerythritol Tri- or tetra (meth) acrylate obtained by adding the above ethylene oxide or propylene oxide, 6 mol or more of ethylene oxide or propylene oxide per 1 mol of dipentaerythritol Poly (meth) acrylate obtained by addition, and more preferably, di (meth) acrylate of diol obtained by adding 4 moles or more of ethylene oxide or propylene oxide to 1 mole of bisphenol A, 3 moles of 1 mole of trimethylolpropane. Diol or tri (meth) acrylate of triol obtained by adding more than mol of ethylene oxide or propylene oxide, tri or tetra (meth) obtained by adding 4 mol or more of ethylene oxide or propylene oxide to 1 mol of pentaerythritol Acrylate.

  N-vinyl-2-pyrrolidone, acryloylmorpholine, vinylimidazole, N-vinylcaprolactam, N-vinylformamide, vinyl acetate, (meth) acrylic acid, (meth) acrylamide, N-hydroxymethylacrylamide or N-hydroxyethyl Acrylamide and their alkyl ether compounds can also be used.

  Furthermore, a polymerizable oligomer can also be used as the ultraviolet curable compound. Examples of the polymerizable oligomer include polyester (meth) acrylate, polyether (meth) acrylate, epoxy (meth) acrylate, and urethane (meth) acrylate.

  In order to obtain an adhesive layer having a glass transition temperature of 25 ° C. or lower, monofunctional (meth) acrylate is 20 to 99 parts by mass and polyfunctional (meth) acrylate is 1 to 80 parts by mass in 100 parts by mass of the ultraviolet curable composition. The monofunctional (meth) acrylate is preferably 30 to 99 parts by mass, the polyfunctional (meth) acrylate is 1 to 70 parts by mass, more preferably the monofunctional (meth) acrylate is 40 to 99 parts by mass, and the polyfunctional (meth). An acrylate is 1-60 mass parts. Particularly preferably, the polyfunctional (meth) acrylate has a tri- or higher functional (meth) acrylate of less than 5 parts by mass.

  In general, a photopolymerization initiator is added to the ultraviolet curable composition. The photopolymerization initiator is not particularly limited as long as it can cure an ultraviolet curable compound represented by a polymerizable monomer and / or a polymerizable oligomer to be used. As the photopolymerization initiator, a molecular cleavage type or a hydrogen abstraction type is suitable for the present invention.

As photopolymerization initiators, benzoin isobutyl ether, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, benzyl, 2,2-dimethoxy-2-phenylacetophenone, 2,4,6-trimethylbenzoyldiphenyl Phosphine oxide, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, etc. Further, other molecular cleavage types such as 1-hydroxycyclohexyl phenyl ketone, benzoyl ethyl ether, benzyl dimethyl ketal, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- (4-Isopro Ruphenyl) -2-hydroxy-2-methylpropan-1-one and 2-methyl-4 ′-(methylthio) -2-morpholinopropiophenone may be used in combination, and a hydrogen abstraction type photopolymerization initiator. Benzophenone, 4-phenylbenzophenone, isophthalophenone, 4-benzoyl-4'-methyl-diphenylsulfide and the like can be used together.
Preferably, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2,2-dimethoxy-2-phenylacetophenone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone, 2 -Methyl-4 '-(methylthio) -2-morpholinopropiophenone, 4-phenylbenzophenone, more preferably 2-isopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone 2-methyl-4 ′-(methylthio) -2-morpholinopropiophenone, 4-phenylbenzophenone.

  Further, as a sensitizer for the photopolymerization initiator, for example, triethylamine, methyldiethanolamine, triethanolamine, p-diethylaminoacetophenone, p-dimethylaminoacetophenone, p-dimethylaminobenzoic acid ethyl, p-dimethylaminobenzoic acid. Amines that do not cause an addition polymerization reaction may be used in combination with the aforementioned polymerizable components, such as isoamyl, N, N-dimethylbenzylamine, and 4,4′-bis (diethylamino) benzophenone. Of course, it is preferable to select and use the photopolymerization initiator and the sensitizer that are excellent in solubility in the curable component and do not inhibit the ultraviolet light transmittance.

  As the ultraviolet curable composition, it is preferable to use a liquid composition at room temperature to 40 ° C. It is preferable not to use a solvent, and even if it is used, it is preferable to keep it as small as possible. When the composition is applied with a spin coater, the viscosity is preferably adjusted to 20 to 1000 mPa · s, and preferably adjusted to 30 to 700 mPa · s, preferably 40 to 500 mPa · s. It is more preferable to prepare so that.

  In order to adjust the viscosity, a polymer having a mass average molecular weight of 10,000 or more can be used as a thickener. In order to obtain a desired viscosity with a small amount of addition, a higher molecular weight polymer, that is, a polymer having a mass average molecular weight of 100,000 or more is preferable, and a polymer having a mass average molecular weight of 1,000,000 or more is more preferable.

  In addition, the ultraviolet curable composition, if necessary, further includes other additives such as thermal polymerization inhibitors, antioxidants typified by hindered phenols, hindered amines, phosphites, plasticizers, and epoxy silanes, Silane coupling agents represented by mercaptosilane, (meth) acrylic silane and the like can be blended for the purpose of improving various properties. It is preferable to select and use those that are excellent in solubility in a curable component and those that do not impair ultraviolet light transmittance. In addition, a commercial item can also be used as the said ultraviolet curable compound. Specifically, for example, SD-661 manufactured by Dainippon Ink Co., Ltd. can be mentioned.

The details of the ultraviolet curable composition used for forming the adhesive layer are as described above. The method of forming the adhesive layer is not particularly limited, but a predetermined amount of an ultraviolet curable composition is applied on the surface (bonded surface) of the barrier layer, and a cover layer is placed thereon, followed by spin coating. It is preferable to spread the agent so that it is uniform between the surface to be bonded and the cover layer, and then irradiate ultraviolet rays from the cover layer side to perform a curing treatment. The irradiation amount is preferably more than 200 mJ / cm ² . More preferably, it is the range of 200-2000 mJ / cm < ² >. As a UV lamp used for curing, for example, 4.2 inch-SPIRAL LAMP manufactured by Xenon Corporation can be used. It is preferable to appropriately set the distance between the lamp surface and the sample surface during ultraviolet irradiation.

In order to move the medium coated with the ultraviolet curable composition to the UV irradiation position (for example, move from the spin table to the UV irradiation table), the substrate is held and lifted at the outer peripheral part or inner peripheral part of the medium. It is desirable to move it. When the medium is supported and lifted from the top by a method such as adsorption, the medium is deformed because the UV curable composition is uncured, or bubbles are mixed into the adhesive layer, resulting in a film of the adhesive layer. It may cause thickness fluctuations and defects. In the case of moving while supporting the outer peripheral portion, it is preferable to periodically clean the support member. In the outer peripheral portion, an uncured ultraviolet curable composition shaken off during spinning may adhere to the outer peripheral edge portion and may adhere to the support member. When the medium is repeatedly moved by the same support member, it may adhere to the medium from the support member and cause a defect.
In addition, at the UV irradiation position (for example, on the UV irradiation table), as a part for supporting the medium, one part or a plurality of parts are supported from among the inner peripheral part, outer peripheral part or middle peripheral part of the substrate (medium). can do. The entire surface may be uniformly supported by a plate-like support member. In the case of supporting a plurality of parts, the support height of each part can be changed. This is because, for example, when only the inner periphery is supported, the unsupported medium outer periphery hangs down under its own weight and is cured in that shape, so that when the medium is warped after curing, the outer periphery also This is a case where warping after curing is suppressed by supporting and suppressing sagging, and the effect of adjusting the media shape after curing by adjusting the height of each supporting member can be expected.

The ultraviolet curing treatment is preferably performed so that the gel fraction of the cured coating film is 90% or more. More preferably, it is 92% or more, more preferably 95% or more, and most preferably 100%.
The gel fraction is an index indicating the degree of curing. A higher value indicates that the curing is progressing, and if it is 90% or more, it can be determined that the curing has sufficiently progressed. The gel fraction can be determined by the following method.
A test piece is cut out from the cured coating film to obtain a sample for gel fraction measurement. The mass of the sample (hereinafter referred to as W1) is measured, immersed in a methyl ethyl ketone solution having a mass 100 times that of W1, and then heated in a heating furnace at 80 ° C. for 8 hours to elute the uncured components. After the heating is completed, the supernatant of the solution is removed within 10 minutes, and it is naturally dried for 48 hours or more in an environment of 25 ° C. and 50%, and then heated and dried in a heating furnace at 100 ° C. for 3 hours. A sample is obtained, and the mass after elution of uncured components (hereinafter referred to as W2) is measured. The supernatant liquid can be removed in the form of suction using a dropper or the like in a state of standing. 80 to 90% of the supernatant is removed, and the remainder is volatilized by natural drying or heat drying. The gel fraction is calculated from the above W1 and W2 by the following formula.
Gel fraction (%) = 100− (W1−W2) / W1 × 100

  The thickness of the adhesive layer is preferably in the range of 0.1 to 100 μm, more preferably in the range of 0.5 to 50 μm, and still more preferably in the range of 1 to 30 μm.

Barrier layer The barrier layer can be provided for improving the storage stability of the recording layer, improving the adhesion between the recording layer and the cover layer, adjusting the reflectance, adjusting the thermal conductivity, and the like.
The material used for the barrier layer is not particularly limited as long as it is a material that transmits light used for recording and reproduction and can express the above functions. For example, in general, It is preferable to use a material that does not cause corrosion due to contact with a reflective layer material such as a gas or moisture, a material that does not cause corrosion in a wet heat environment, and a dielectric material. preferable.
Specifically, a material made of nitride, oxide, carbide, sulfide such as Zn, Si, Ti, Te, Sn, Mo, Ge, Nb, Ta is preferable. MoO ₂ , GeO ₂ , TeO, SiO ₂ , TiO ₂ , ZnO, SnO ₂ , ZnO—Ga ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ are preferable, SnO ₂ , ZnO—Ga ₂ O ₃ , SiO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ Is more preferable.

The barrier layer can be formed by a vacuum film forming method such as vacuum deposition, DC sputtering, RF sputtering, or ion plating. Among these, it is more preferable to use sputtering.
The thickness of the barrier layer is preferably in the range of 1 to 200 nm, more preferably in the range of 2 to 100 nm, and still more preferably in the range of 3 to 50 nm.

Cover layer The cover layer is bonded onto the barrier layer via an adhesive or an adhesive.
The cover layer is not particularly limited as long as it is a transparent film, but is not limited to acrylic resins such as polycarbonate and polymethyl methacrylate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers; epoxy resins; amorphous polyolefins Polyester; cellulose triacetate or the like is preferably used, and among them, polycarbonate or cellulose triacetate is more preferably used.
Note that “transparent” means that the transmittance is 80% or more with respect to light used for recording and reproduction. In the optical information recording medium of the present invention, preferably, the ultraviolet curable composition applied on the barrier layer is cured by irradiating with ultraviolet rays through the cover layer. Therefore, it is preferable that the cover layer has ultraviolet transparency. Specifically, it is preferable to have a transmittance of 80% or more with respect to the ultraviolet rays irradiated for curing the ultraviolet curable composition.

Further, the cover layer may contain various additives as long as the effects of the present invention are not hindered. For example, a UV absorber for cutting light having a wavelength of 400 nm or less and / or a dye for cutting light having a wavelength of 500 nm or more may be contained.
Further, as the surface physical properties of the cover layer, it is preferable that the surface roughness is 5 nm or less for both the two-dimensional roughness parameter and the three-dimensional roughness parameter.
Further, from the viewpoint of the concentration of light used for recording and reproduction, the birefringence of the cover layer is preferably 10 nm or less.

The thickness of the cover layer, the wavelength and the NA of the the laser beam irradiation for recording and reproducing, the wavelength or the like of the ultraviolet rays irradiated for curing the ultraviolet-curable composition, as appropriate, may be defined However, in the present invention, it is preferably in the range of 0.01 to 0.5 mm, and more preferably in the range of 0.05 to 0.12 mm.
Further, the total thickness of the cover layer and the adhesive layer is preferably 0.09 to 0.11 mm, and more preferably 0.095 to 0.105 mm.
The light incident surface of the cover layer is provided with a protective layer (a hard coat layer 44 in the embodiment shown in FIG. 1 described later) for preventing the light incident surface from being damaged during the production of the optical information recording medium. May be.

  The cover layer may be formed by spin coating using a UV curable resin.

Other Layers The optical information recording medium of the present invention may have other arbitrary layers in addition to the essential layers as long as the effects of the present invention are not impaired. As other optional layers, for example, a label layer having a desired image formed on the back surface of the substrate (the non-formation surface side opposite to the side where the write-once recording layer is formed), a reflective layer and recording Examples thereof include an interface layer provided between the layers. Here, the label layer can be formed using an ultraviolet curable resin, a thermosetting resin, a heat drying resin, or the like.
The essential and optional layers described above may be a single layer or a multilayer structure.

  By irradiating the optical information recording medium of the present invention with laser light, information can be recorded on the recording layer. Information recording on the optical information recording medium is performed by changing the optical characteristics of the portion of the recording layer irradiated with the laser light. The change in optical properties is caused by the fact that the portion of the recording layer irradiated with the laser light absorbs the light and the temperature rises locally, causing a physical or chemical change (for example, generation of pits). Conceivable. Reading (reproduction) of information recorded on the recording layer is not changed from a portion (recording portion) where the optical characteristics of the recording layer are changed by irradiating laser light having the same wavelength as that of the recording laser light, for example. This can be done by detecting a difference in optical characteristics such as reflectance from a part (unrecorded part). As described above, in the present invention, recording of information is preferably performed by thermally decomposing the phthalocyanine derivative by laser light irradiation and forming voids in the pits by the generated gas. More preferably, the phthalocyanine derivative generates heat by absorbing laser light, and the heat generated thereby decomposes a substituent or a dye skeleton in the phthalocyanine derivative to generate a gas. As a result, voids are formed in the recording layer, and a large difference in refractive index can be generated between the portion where the voids are formed by laser light irradiation and the laser light non-irradiated portion, and the recording characteristics can be improved. Conceivable. The wavelength of the laser beam is preferably 390 to 440 nm. Details of information recording on the optical information recording medium of the present invention will be described later.

[Information recording method]
Furthermore, the present invention relates to an information recording method for recording information on a recording layer by irradiating the optical information recording medium of the present invention with laser light having a wavelength of 390 to 440 nm.

  The recording light is a laser light having a wavelength of 390 to 440 nm, and a semiconductor laser light having an oscillation wavelength in the range of 440 nm or less is suitably used, and a preferred light source is an oscillation in the range of 390 to 440 (more preferably 390 to 415 nm). A blue-violet semiconductor laser beam having a wavelength and a blue-violet SHG laser beam having a center oscillation wavelength of 425 nm, which is a half wavelength of an infrared semiconductor laser beam having a center oscillation wavelength of 850 nm using an optical waveguide device, can be given. In particular, it is preferable to use a blue-violet semiconductor laser beam having an oscillation wavelength in the range of 390 to 415 nm in terms of recording density. The information recorded as described above is reproduced by irradiating the semiconductor laser light from the cover layer side while rotating the optical information recording medium at the same constant linear speed as described above, and detecting the reflected light. Can do.

Specifically, information recording on the optical information recording medium shown in FIG. 2 is performed as follows, for example.
First, while rotating the optical information recording medium at a constant linear velocity (for example, 0.5 to 10 m / second) or a constant angular velocity, a recording laser beam 46 such as a semiconductor laser beam is applied from the cover layer 16 side. Irradiation is performed through one objective lens 42 (for example, the numerical aperture NA is 0.85). By the irradiation of the laser beam 46, the write-once recording layer 14 absorbs the laser beam 46 and the temperature rises locally, causing a physical or chemical change (for example, generation of pits) to change its optical characteristics. Thus, it is considered that information is recorded.
The other details of the information recording method of the present invention are as described for the optical information recording medium of the present invention.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the embodiments shown in the examples.

<< Preparation of UV-curable composition >>
The UV curable composition used as an adhesive for forming an adhesive layer is obtained by adding a polyfunctional monomer and a thickener to a monofunctional monomer, and then adding a photopolymerization initiator and stirring to make it uniform in the dark. Can be prepared. Hereinafter, the preparation method will be described by taking the ultraviolet curable composition F as an example. The ultraviolet curable compositions A to E can be obtained in the same manner.

1. Preparation Example: UV curable composition F
Cross-linking agent obtained by reacting with acrylic acid chloride after adding 40 mol of ethylene oxide to 1 mol of glycerin as a polyfunctional monomer to 2-ethylhexyl acrylate (21 g: Wako Pure Chemical Industries, Ltd.) as a monofunctional monomer (0.5 g, NK Esther ASO 40EO manufactured by Shin-Nakamura Kogyo Co., Ltd.), polybutyl acrylate (7 g: Aldrich, Mw = 101000, Mn = 38000) as a thickener, and 1-hydroxycyclohexyl as a photopolymerization initiator Phenyl ketone (0.5 g: Wako Pure Chemical Industries, Ltd.) was stirred in the dark for 3 hours and allowed to stand overnight to obtain an ultraviolet curable composition F.

2. Viscosity Measurement Viscosity at 25 ° C. was measured using the R500 type viscometer manufactured by Toki Sangyo Co., Ltd. for the obtained ultraviolet curable compositions A to F, Dainippon Ink & Co. SD-640 and SD-661. . The results are shown in Table 2.

<< Production of optical information recording medium >>
(Production of substrate)
Thickness 1.1 mm, outer diameter 120 mm, inner diameter 15 mm, spiral pre-groove (track pitch: 320 nm, groove width: groove (recess) width 190 nm, groove depth: 47 nm, groove inclination angle: 65 °, wobble amplitude: An injection molded substrate made of polycarbonate resin having a thickness of 20 nm) was produced. Mastering of the stamper used at the time of injection molding was performed using laser cutting (351 nm).

(Formation of light reflection layer)
An ANC light reflecting layer (Ag: 98.1 at%, Nd: 0.7 at%, as a vacuum film-forming layer having a film thickness of 60 nm was formed on the substrate by DC sputtering in an Ar atmosphere using Cube manufactured by Unaxis. Cu: 0.9 at%) was formed. The film thickness of the light reflecting layer was adjusted by the sputtering time.

(Formation of write-once recording layer)
1.2 g of exemplary compound (A-30) was added and dissolved in 100 ml of 2,2,3,3-tetrafluoropropanol to prepare a dye-containing coating solution. And the prepared pigment | dye containing coating liquid was apply | coated on the conditions of 23 degreeC and 50% RH, changing the rotation speed to 300-4000 rpm with a spin coat method on the light reflection layer. Then, it was stored at 23 ° C. and 50% RH for 1 hour to form a write-once recording layer. The thickness of the write-once recording layer was 40 nm on the groove and 15 nm on the land.

  After the write-once recording layer was formed, annealing treatment was performed in a clean oven. The annealing treatment was performed by supporting the substrate on a vertical stack pole while leaving a gap with a spacer, and holding at 80 ° C. for 1 hour.

(Formation of barrier layer)
Thereafter, a barrier layer having a thickness of 5 nm made of Nb ₂ O ₅ was formed by DC sputtering in an Ar atmosphere on the write-once recording layer using Cube manufactured by Unaxis.

The medium on which the barrier layer was formed was placed on a spin coater, and the ultraviolet curable composition F was applied in a ring shape around the inner periphery of 30 mm. After a polycarbonate film having an inner diameter of 15 mm and an outer diameter of 120 mm (Teijin Pure Ace, thickness: 90 μm) was placed thereon, 2000 to 8000 r. p. m. It was rotated at the number of rotations. As a result, the adhesive was extended to the outer periphery by centrifugal force, and an adhesive layer having a uniform thickness could be obtained. This sample was moved to a UV light irradiation table, irradiated with UV light, and the UV adhesive was cured. At this time, the UV lamp used for curing was a 4.2 inch-SPIRAL LAMP manufactured by Xenon Corporation, and was cured by irradiating a flash with an irradiation time of 0.5 seconds each time. The distance between the lamp surface and the sample surface was about 35 mm. The amount of ultraviolet irradiation was 2000 mJ / cm ² . The thickness of the formed adhesive layer was 10 μm.
Thereby, the optical information recording medium of Example 1 was produced.

[Examples 2 to 6, Comparative Examples 1 and 2]
Using the ultraviolet curable composition shown in Table 2 instead of the ultraviolet curable composition F, the ultraviolet irradiation amount was changed as shown in Table 2 by changing the ultraviolet irradiation time for the curing treatment of the composition. An optical information recording medium was produced by the same method as in Example 1 except that.

Recording layer dyes using the mass reduction rate in the main weight loss process of recording layer dyes are described in Seiko Instruments Inc. Using EXSTAR6000, the temperature was increased at a rate of 10 ° C./min in the range of 30 ° C. to 550 ° C. under a N ₂ air flow (flow rate 200 ml / min) to determine the mass reduction rate in the main weight loss process. The mass reduction rate of the exemplary compound (A-30) in the main weight loss process was 68%.

Ultraviolet irradiation amount The ultraviolet irradiation amount irradiated for curing the adhesive layer was measured as follows.
An EC-100FL model manufactured by Ushio Electric Co., Ltd. was used as the irradiance measuring instrument, and the measurement was performed in the integrated light quantity measurement mode. A polycarbonate film (Teijin Pure Ace, thickness: 90 μm) is placed on the light-receiving part of this measuring machine and set on the UV light irradiation part. Irradiation was performed 10 times, and the integrated light quantity at each time was measured. When the relationship between the irradiation time and the integrated light amount was plotted, the relationship between the irradiation time and the integrated light amount showed a good linear relationship. Therefore, the slope of the approximate straight line passing through the origin is defined as the irradiation amount per unit time, and the product of the irradiation amount per unit time and the irradiation time is defined as the irradiation amount. The results are shown in Table 2 below. Since the light receiving part of the measuring machine is at a radius of 40 mm, the values shown in Table 2 are obtained by using the measurement result at a radius of 40 mm as a representative value. Depending on the lamp, the in-plane strength may vary. .
Although this measuring machine measures relative values and has no units, Table 2 shows the numerical values obtained by substituting mJ / cm ² for energy. This is because the integrated amount of light when irradiated for 3 seconds without placing a polycarbonate film substantially coincides with the manufacturer data (measured as energy having a unit of mJ / cm ² ).

Measurement of gel fraction With respect to the optical information recording media of Examples 2 to 6 and Comparative Examples 1 and 2, the gel fraction of the adhesive layer after the curing treatment was measured as follows.
A cut was made with a knife at the outer peripheral edge of the polycarbonate film side of each of the produced media to create a state where the film was partially peeled, and the entire film was peeled off from the substrate. There are some parts where the reflective layer is peeled off on the film side, but most are peeled off at the interface between the reflective layer and the adhesive and separated into a substrate with the reflective layer and a film with the adhesive layer. It was. The adhesive layer on the film was scraped off with a metal spatula to obtain a cured adhesive layer sample. Depending on the amount of the cured adhesive layer sample, this operation was performed on a plurality of media to ensure the amount necessary for mass measurement.
The mass W1 of the obtained cured adhesive layer sample was measured and immersed in a methyl ethyl ketone solution having a mass 100 times that of W1, and then heated in a heating furnace at 80 ° C. for 8 hours to elute uncured components. The supernatant of the solution is removed within 10 minutes after the completion of heating, and it is naturally dried for 48 hours or more in an environment of 25 ° C. and 50%, and then heat-dried in a heating furnace at 100 ° C. for 3 hours to elute uncured components. The mass W2 after elution of uncured components was measured. The supernatant liquid was removed by sucking with a dropper or the like in a state of standing. 80 to 90% of the supernatant was removed, and the rest was volatilized by natural drying and heat drying. Although some of the eluate remained, priority was given to not removing the precipitated non-elute, and care was taken not to absorb the precipitate.
The gel fraction was calculated using the following formula.
Gel fraction (%) = 100− (W1−W2) / W1 × 100
If the gel fraction reached 90%, it was judged that the curing had progressed sufficiently. The results are shown in Table 2.

<Measurement of glass transition temperature and storage modulus of adhesive layer>
(1) Preparation of sample for measurement of dynamic viscoelastic behavior After applying UV curable compositions A to F and Dainippon Ink & Chemicals SD-640 and SD-661 on a glass substrate, respectively, metal halide lamp M02-L31 Samples for measurement (samples 1 to 6 and comparative sample 1) were cured by irradiation with ultraviolet rays at a dose shown in Table 2 in a nitrogen atmosphere using (Graphics made, with cold mirror, lamp output 120 W / cm). 2) was prepared.
(2) Measurement of glass transition temperature (Tg) The obtained cured coating film was cut into a length of 2 cm and a width of 0.5 cm and a dynamic viscoelasticity measuring device: DVA-200 (IT Measurement Control Co., Ltd.). The dynamic viscoelastic behavior at a frequency of 1 Hz was measured (temperature rising speed 5 ° C./min). The measurement mode was a tensile mode or a shear mode (see Table 3). Similarly, the storage elastic modulus at 30 ° C. was determined. Table 3 shows the measurement results.
(3) Measurement of glass transition temperature (DSC) The glass transition temperature (DSC) of the cured coating film obtained in the same manner as in (2) was measured by SC / DSC. Table 3 shows the measurement results.
The measurement method will be described below.
DSC apparatus: Seiko Instruments Inc. A sample is sealed in a closed cell made of SUS using DSC6200R manufactured, and the temperature is raised at 10 ° C./min in the range of −100 ° C. to 100 ° C. to obtain the first glass transition temperature. Further, the temperature is lowered from 100 ° C. to −100 ° C. at 50 ° C./min, and then the temperature is raised at 10 ° C./min in the range from −100 ° C. to 100 ° C. to obtain the second glass transition temperature. This point is called the glass transition temperature (DSC).
In addition, in order to measure the glass transition temperature and the storage elastic modulus, the cured coating film in the measurement sample was formed thicker than the adhesive layers in the optical information recording media of Examples and Comparative Examples. Table 3 below shows the thicknesses of the cured coating films of Samples 2 to 6 and Comparative Samples 1 and 2. However, since the glass transition temperature and the storage elastic modulus are not affected by the film thickness, the results shown in Table 3 below can be regarded as the evaluation results of the corresponding examples and comparative examples, respectively.

<Evaluation of recording characteristics>
1. C / N (carrier-to-noise ratio) evaluation (2TC / N value)
The produced optical information recording medium was 0.16 μm at a clock frequency of 66 MHz and a linear velocity of 4.92 m / s using a recording / reproduction evaluation machine (manufactured by Pulstec Inc .: DDU1000) loaded with a 403 nm laser and NA 0.85 pickup. The signal (2T) was recorded and reproduced, and the output was measured with a spectrum analyzer (FSP-3 type manufactured by Rohde & Schwartz). The peak output seen at around 16 MHz after recording was defined as Carrier output, the output at the same frequency before recording was defined as Noise output, and the output after recording−the output before recording was defined as the C / N value. Recording was done on the groove. The recording power was in the range of 1 to 8 mW, and the reproducing power was 0.3 mW.
Further, when the recording power is 6 mW, the C / N value is larger than 35 dB, which is a practically usable level. A case where the C / N value at a recording power of 6 mW is 35 dB or more is “◯”. The results are shown in Table 4.

2.9 Evaluation of T signal waveform Using the recording / reproduction evaluation machine (PULSETECH Co., Ltd .: DDU1000) loaded with a 403 nm laser and NA 0.85 pickup, the produced optical information recording medium was used with a clock frequency of 66 MHz and a linear velocity of 4.92 m / second. At s, a signal of about 0.16 μm (9T signal) was recorded and reproduced, and the output was measured with a spectrum analyzer (FSP-3 type manufactured by Rohde & Schwartz). Recording was done on the groove. At this time, the peak power value used for recording was measured while increasing the power every 2.0 mW from 2.0 mW to 10.0 mW, and the recording power having the waveform closest to the rectangular wave was determined as the optimum recording power. It is extremely important that the 9T signal waveform shows a waveform close to a rectangle because it leads to a reduction in reading error of the recording signal.
A signal (9T signal) of about 0.72 μm was recorded and reproduced with the optimum recording power, and an output waveform was measured with an oscilloscope DL7440 type manufactured by Yokogawa Electric Corporation. Note that 200 waveforms were taken and averaged and used as an average waveform.
An explanatory diagram of the 9T signal waveform is shown in FIG. In FIG. 3, FIG. P and FIG. R show an image of a bad 9T waveform, and FIG. Q shows an image of a good 9T waveform. The horizontal axis represents time, and the vertical axis represents the reflected signal voltage. The waveforms obtained are roughly as shown in FIG. 3 and FIG. 3 in FIG. When both the chart P and the chart Q can be taken in the process of increasing the recording power, there is a point where a waveform close to the chart Q is obtained between the respective recording powers. The shape of the 9T waveform was evaluated by ◯ when the 9T waveform of FIG. Q in FIG. 3 was shown, and by x when the 9T waveform of FIG. P or R was shown. The evaluation results of Examples 2 and 5 and Comparative Example 1 are shown in Table 4.

As shown in Table 3, the media of Examples 2 and 5 gave good results in any evaluation of 2TC / N value and 9T waveform.
Further, in the medium of Comparative Example 1 having a high Tg (Tg> 25 ° C.) adhesive layer, the amplitude of the first half of the recording portion (region where Time / ns is short) is hardly visible, whereas the adhesive layer having a Tg of 25 ° C. or lower is used With the media (Examples 2 and 5), sufficient amplitude was obtained in the first half of the recording part.

  The recording performance of Examples 1, 3, 4 and 6 and Comparative Example 2 were similarly evaluated, and it was confirmed that the media of Examples 1, 3, 4 and 6 showed good recording performance. On the other hand, the recording performance of the medium of Comparative Example 2 was low.

[Example 7]
An optical information recording medium was produced in the same manner as in Example 1 except that the exemplified compound (A-50) (a thermal decomposition rate of 99% in the main weight loss process) was used as the recording layer dye.

[Comparative Example 3]
Except that the compound (I-3) described in Example 3 of JP-A-2005-279964 (mass reduction rate of 8% in the main weight loss process) was used as the recording layer dye, light was obtained in the same manner as in Example 1. An information recording medium was produced.

  For Example 7 and Comparative Example 3, the recording performance was evaluated by the same method as described above. The medium of Example 7 showed good recording performance. On the other hand, the recording performance of the medium of Comparative Example 3 was low.

  The optical information recording medium of the present invention is suitable as a Blu-ray optical information recording medium for recording information by irradiating a short wavelength laser beam.

It is explanatory drawing of the measuring method of the mass reduction | decrease rate in the main weight loss process in a thermal mass spectrometry. It is a schematic sectional drawing which shows an example of the optical information recording medium of this invention. An explanatory view of a 9T signal waveform is shown.

Explanation of symbols

10A ... first optical information recording medium 12 ... substrate 14 ... recording layer 16 ... cover layer 18 ... light reflecting layer 20 ... barrier layer 22 ... adhesive layer 42 ... first objective lens 44 ... hard coat layer 46 ... laser light

Claims (7)

An optical information recording medium having a reflective layer, a recording layer, a barrier layer, and a cover layer in this order on a surface of a substrate having a plurality of grooves and a pre-groove composed of lands located between adjacent grooves on the surface. And
The track pitch of the pregroove is in the range of 50 to 500 nm,
The recording layer has a thickness in the range of 1 to 100 nm on the land and in the range of 5 to 150 nm on the groove.
The recording layer contains a thermally decomposable compound represented by the following general formula (I) and having a mass reduction rate of 10% or more in the main weight loss process in thermal mass spectrometry,
An optical information recording medium comprising a layer having a glass transition temperature of 25 ° C. or lower formed by subjecting an ultraviolet curable composition to a curing treatment between the barrier layer and the cover layer.

[In General Formula (I), X ¹ and X ² each independently represents an oxygen atom, a sulfur atom or N—R, R represents an alkyl group, an aryl group, or a heterocyclic group, and Za ¹ and Za ² each independently represents a group of atoms necessary to complete a 5- or 6-membered heterocyclic ring, and L ¹ , L ² and L ³ each independently represents a substituted or unsubstituted methine group. (However, when there is a substituent on L ^{1 to} L ³ , they may be linked to each other to form a ring), j represents 0 or 1, M ₁ represents a charge balanced counter ion, m 1 Represents a number from 0 to 10 which is necessary for neutralizing the charge of the molecule. ] The ratio of the thickness of the recording layer on the land to the recording layer on the groove [(thickness of recording layer on land) / (thickness of recording layer on groove)] is in the range of 0.1 to 1. The optical recording information medium according to claim 1. The optical information recording medium according to claim 1 or 2, wherein the compound represented by the general formula (I) is a compound represented by the following general formula (II-1) or the following general formula (II-2).

[In the general formulas (II-1) and (II-2), Zb represents an atomic group necessary for forming an indolenine nucleus, a benzoindolenine nucleus, a benzimidazole nucleus, a benzoxazole nucleus, or a benzothiazole nucleus. , Xa represents an oxygen atom, a sulfur atom, C (R ₃ ) (R ₄ ) or N—R ₅ , and R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently an alkyl group or Represents an aryl group, and L ₄ represents a substituted or unsubstituted methine group. M ₁ and m 1 have the same definition as in general formula (I). ] The optical information recording medium according to claim 1 or 2, wherein the compound represented by the general formula (I) is a compound represented by the following general formula (III).

[In General Formula (III), Xb and Xc each independently represent an oxygen atom, a sulfur atom, or N—R ₁₄ , and R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ each independently represents a hydrogen atom, an alkyl group or an aryl group, and L ₅ , L ₆ and L ₇ each independently represents a substituted or unsubstituted methine group. However, when there are substituents on L _{5 to} L ₇ , these substituents may be linked to each other to form a ring. k represents 0 or 1; M ₁ and m 1 have the same definition as in the general formula (I-1). ] The said ultraviolet curable composition contains 20-99 mass parts of monofunctional (meth) acrylate, and 1-80 mass parts of polyfunctional (meth) acrylate with respect to 100 mass parts of ultraviolet curable compositions. 5. The optical information recording medium according to any one of 4 above. The optical information recording medium according to claim 1, which is used for recording information by irradiating a laser beam having a wavelength of 390 to 440 nm. An information recording method for recording information on a recording layer of an optical information recording medium by irradiating the optical information recording medium according to any one of claims 1 to 5 with laser light having a wavelength of 390 to 440 nm.

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