JP2005305837A - Coating liquid, optical recording medium and manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of an optical recording medium, by which a recording layer having few deterioration with time can be formed and, in addition, which dissolves a board very little, and the coating liquid used therefor and the optical recording medium obtained thereby. <P>SOLUTION: This manufacturing method of the optical recording medium has a process for coating a coating liquid including a solvent and a coloring matter dissolved in the solvent on a board under the condition that, as the solvent, one including a hydroxyl compound having a monovalent hydrocarbon group with a carbon-carbon triple bond, an alkoxy group or an acyl group is employed and, as the coloring matter, one including a specifically structured cyanine compound and a chelate compound consisting of an azo compound and a metal is employed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coating liquid for use in the production of an optical recording medium, a method for producing an optical recording medium using the same, and an optical recording medium obtained thereby.

  An optical recording medium records information by irradiating a recording layer with a laser or the like and changing the shape, magnetic domain change, phase change, or the like of the recording layer. As such an optical recording medium, an optical recording medium in which a recording layer made of an optical recording material containing an organic dye is formed on a substrate is known. An optical recording medium having a recording layer containing an organic dye is widely used as a CD-R or DVD ± R (recordable DVD) because it can perform highly sensitive recording.

For example, Patent Document 1 discloses an optical recording material containing a cyanine compound having a specific structure. By applying this optical recording material on a substrate in the state of a coating solution dissolved in various organic solvents, a recording layer can be formed on the substrate in the optical recording medium. It has been shown that an optical recording medium having such a recording layer can sufficiently cope with high-speed recording.
JP 2003-231359 A

  In recent years, when preparing a coating solution containing an optical recording material, a halogenated alcohol, particularly tetrafluoropropanol (hereinafter, abbreviated as “TFP”) is used as an organic solvent to improve the solubility of the dye as described above. It is frequently used because of its superiority. However, as a result of investigations by the present inventors, it has been found that when TFP is used as the organic solvent, for example, the following inconveniences are likely to occur.

  That is, when the coating liquid as described above is used when forming the recording layer, the organic solvent used in the coating liquid often remains in the obtained recording layer. Such a residual organic solvent usually hardly deteriorates the recording characteristics and reproduction characteristics of the recording layer, but the recording layer in which the TFP remains is more time-consuming than the case in which other solvents remain. It has been found that characteristic deterioration is likely to occur. Although this factor is not clear, it is assumed that the TFP in the recording layer generates fluorine radicals by laser irradiation during recording or reproduction, and this fluorine radical alters the dye, reflection film, etc. Is done.

  Therefore, the present inventors have studied organic solvents other than TFP in order to reduce such deterioration with time. However, for example, among the solvents described in Patent Document 1, when a solvent other than TFP is used, depending on the conditions, there are many that dissolve the substrate of the optical recording medium made of polycarbonate. For this reason, it turned out that it is not necessarily preferable as an organic solvent used for a coating liquid.

  The present invention has been made in view of such circumstances, and it is possible to form a recording layer that does not easily deteriorate with time, and an optical recording medium that hardly causes dissolution of the substrate when the recording layer is formed. It is an object of the present invention to provide a manufacturing method, a coating solution used therefor, and an optical recording medium obtained by this manufacturing method.

  As a result of further detailed studies by the present inventors, it was found that the above object can be achieved by using a hydroxyl compound having a specific functional group as an organic solvent to be contained in the coating liquid, and the present invention has been completed. I came to let you.

［式（１）中、Ｒ^１１は、炭素−炭素三重結合を有する一価の炭化水素基、炭素数１〜４のアルコキシ基又は炭素数１〜５のアシル基、Ｒ^１２は、炭素数１〜８のアルキレン基を示す。また、式（２）中、Ｒ^２１、Ｒ^２２、Ｒ^２３及びＲ^２４は、それぞれ独立に、置換基を有していてもよいベンジル基又は炭素数１〜４のアルキル基、Ｒ^２５は、水素原子、ハロゲン原子、炭素数１〜４のアルキル基、置換基を有していてもよいアリール基、置換基を有していてもよいアラルキル基又はシアノ基、Ｒ^２６及びＲ^２７は、それぞれ独立に、置換基を有していてもよいベンゼン環又は置換基を有していてもよいナフタレン環を構成する原子群、Ｒ^２８及びＲ^２９は、それぞれ独立に、置換基を有していてもよいアリール基又は炭素数１〜４のアルキル基を示す。ただし、Ｒ^２１、Ｒ^２２、Ｒ^２３及びＲ^２４のうちの少なくとも一つの基はメチル基ではない。なお、Ｒ^２１とＲ^２２及び／又はＲ^２３とＲ^２４は、互いの炭素同士が結合して３〜６員環を形成していてもよい。］ That is, the method for producing an optical recording medium of the present invention includes a step of applying a coating solution containing a solvent and a dye dissolved in the solvent on a substrate, and the solvent is represented by the following general formula (1). What contains the compound represented is used, The pigment | dye containing the compound represented by following General formula (2) and the chelate compound of an azo compound and a metal is used as a pigment | dye.

[In Formula (1), R ¹¹ is a monovalent hydrocarbon group having a carbon-carbon triple bond, an alkoxy group having 1 to 4 carbon atoms, or an acyl group having 1 to 5 carbon atoms, and R ¹² is carbon number 1 Represents an alkylene group of ~ 8. In formula (2), R ²¹ , R ²² , R ²³ and R ²⁴ are each independently a benzyl group which may have a substituent or an alkyl group having 1 to 4 carbon atoms, R ²⁵ is A hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group which may have a substituent, an aralkyl group or a cyano group which may have a substituent, R ²⁶ and R ²⁷ are respectively Independently, the benzene ring which may have a substituent or the atomic group constituting the optionally substituted naphthalene ring, R ²⁸ and R ²⁹ each independently have a substituent. Or an aryl group or an alkyl group having 1 to 4 carbon atoms. However, at least one group of R ²¹ , R ²² , R ²³ and R ²⁴ is not a methyl group. R ²¹ and R ²² and / or R ²³ and R ²⁴ may be bonded to each other to form a 3- to 6-membered ring. ]

  In such a method for producing an optical recording medium, a monovalent hydrocarbon group (preferably ethynyl group) having a triple bond, an alkoxy group having 1 to 4 carbon atoms, or an acyl group having 1 to 5 carbon atoms is used as a solvent for the coating solution. The thing containing the hydroxyl compound which has is used. Even if such a hydroxyl compound remains in the recording layer and is irradiated with a laser or the like, a substance that causes deterioration of the characteristics of the recording layer hardly occurs. For this reason, the optical recording medium obtained by such a manufacturing method has little deterioration of the recording layer over time.

  The hydroxyl compound is excellent in the solubility of the dye containing the compound represented by the general formula (2), but hardly dissolves polycarbonate which is a general substrate material. For this reason, in the said manufacturing method, when a coating liquid is apply | coated on a board | substrate, the problem that a board | substrate will melt | dissolve hardly arises.

  Furthermore, TFP that has been conventionally used as an organic solvent to be contained in a coating solution is more expensive than other solvents. On the other hand, the hydroxyl compound is a compound that is available at a relatively low cost. Therefore, according to the manufacturing method of the present invention, the manufacturing cost of the optical recording medium can be reduced as compared with the case of using the coating liquid containing TFP.

  In addition, the compound represented by the general formula (2) has a property of being excellent in absorbability with respect to light having a relatively short wavelength (620 to 690 nm) used for write-once DVD. For this reason, according to the recording layer formed with the pigment | dye containing this compound, it becomes possible to perform a high-density recording.

  In addition, the compound represented by the general formula (2) has a characteristic that heat can be rapidly dispersed even when heated by a recording laser. For this reason, a recording layer containing such a compound is unlikely to cause so-called thermal interference, in which the heat generated when the previous pit is formed has an effect when the next pit is formed. Therefore, an optical recording medium having such a recording layer is unlikely to cause a write error even when high-speed recording is performed.

  In the method for producing an optical recording medium of the present invention, the coating solution may contain a solvent other than the compound represented by the general formula (1), but the recording layer deteriorates with time. From the viewpoint of reducing, it is preferable that the solvent does not contain at least tetrafluoropropanol.

Furthermore, in the compound represented by the general formula (2), at least one of R ²¹ , R ²² , R ²³ and R ²⁴ is more preferably a benzyl group which may have a substituent. It is. Such a compound is particularly excellent in the above-described characteristics of dispersing heat. For this reason, an optical recording medium having a recording layer containing such a compound is more unlikely to cause a recording error when performing high-speed recording.

［式（１）中、Ｒ^１１は、炭素−炭素三重結合を有する一価の炭化水素基、炭素数１〜４のアルコキシ基又は炭素数１〜５のアシル基、Ｒ^１２は、炭素数１〜８のアルキレン基を示す。また、式（２）中、Ｒ^２１、Ｒ^２２、Ｒ^２３及びＲ^２４は、それぞれ独立に、置換基を有していてもよいベンジル基又は炭素数１〜４のアルキル基、Ｒ^２５は、水素原子、ハロゲン原子、炭素数１〜４のアルキル基、置換基を有していてもよいアリール基、置換基を有していてもよいアラルキル基又はシアノ基、Ｒ^２６及びＲ^２７は、それぞれ独立に、置換基を有していてもよいベンゼン環又は置換基を有していてもよいナフタレン環を構成する原子群、Ｒ^２８及びＲ^２９は、それぞれ独立に、置換基を有していてもよいアリール基又は炭素数１〜４のアルキル基を示す。ただし、Ｒ^２１、Ｒ^２２、Ｒ^２３及びＲ^２４のうちの少なくとも一つの基はメチル基ではない。なお、Ｒ^２１とＲ^２２及び／又はＲ^２３とＲ^２４は、互いの炭素同士が結合して３〜６員環を形成していてもよい。］ The present invention also provides a coating solution for use in the optical recording medium of the present invention. That is, the coating solution of the present invention is a coating solution for forming a recording layer of an optical recording medium and contains a solvent and a dye dissolved in the solvent. The solvent is represented by the following general formula (1). The coloring matter contains a compound represented by the following general formula (2) and a chelate compound of an azo compound and a metal.

[In Formula (1), R ¹¹ is a monovalent hydrocarbon group having a carbon-carbon triple bond, an alkoxy group having 1 to 4 carbon atoms, or an acyl group having 1 to 5 carbon atoms, and R ¹² is carbon number 1 Represents an alkylene group of ~ 8. In formula (2), R ²¹ , R ²² , R ²³ and R ²⁴ are each independently a benzyl group which may have a substituent or an alkyl group having 1 to 4 carbon atoms, R ²⁵ is A hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group which may have a substituent, an aralkyl group or a cyano group which may have a substituent, R ²⁶ and R ²⁷ are respectively Independently, the benzene ring which may have a substituent or the atomic group constituting the optionally substituted naphthalene ring, R ²⁸ and R ²⁹ each independently have a substituent. Or an aryl group or an alkyl group having 1 to 4 carbon atoms. However, at least one group of R ²¹ , R ²² , R ²³ and R ²⁴ is not a methyl group. R ²¹ and R ²² and / or R ²³ and R ²⁴ may be bonded to each other to form a 3- to 6-membered ring. ]

［式（１）中、Ｒ^１１は、炭素−炭素三重結合を有する一価の炭化水素基、炭素数１〜４のアルコキシ基又は炭素数１〜５のアシル基、Ｒ^１２は、炭素数１〜８のアルキレン基を示す。また、式（２）中、Ｒ^２１、Ｒ^２２、Ｒ^２３及びＲ^２４は、それぞれ独立に、置換基を有していてもよいベンジル基又は炭素数１〜４のアルキル基、Ｒ^２５は、水素原子、ハロゲン原子、炭素数１〜４のアルキル基、置換基を有していてもよいアリール基、置換基を有していてもよいアラルキル基又はシアノ基、Ｒ^２６及びＲ^２７は、それぞれ独立に、置換基を有していてもよいベンゼン環又は置換基を有していてもよいナフタレン環を構成する原子群、Ｒ^２８及びＲ^２９は、それぞれ独立に、置換基を有していてもよいアリール基又は炭素数１〜４のアルキル基を示す。ただし、Ｒ^２１、Ｒ^２２、Ｒ^２３及びＲ^２４のうちの少なくとも一つの基はメチル基ではない。なお、Ｒ^２１とＲ^２２及び／又はＲ^２３とＲ^２４は、互いの炭素同士が結合して３〜６員環を形成していてもよい。］ The present invention further provides an optical recording medium obtained by the production method of the present invention. In such an optical recording medium, the recording layer contains a predetermined amount of the solvent used in the coating solution in addition to the compound represented by the general formula (2) and the chelate compound of the azo compound and the metal. That is, the optical recording medium of the present invention includes a substrate and a recording layer formed on the substrate, and the recording layer is represented by the compound represented by the following general formula (1), the following general formula (2). And a chelate compound of an azo compound and a metal.

[In Formula (1), R ¹¹ is a monovalent hydrocarbon group having a carbon-carbon triple bond, an alkoxy group having 1 to 4 carbon atoms, or an acyl group having 1 to 5 carbon atoms, and R ¹² is carbon number 1 Represents an alkylene group of ~ 8. In formula (2), R ²¹ , R ²² , R ²³ and R ²⁴ are each independently a benzyl group which may have a substituent or an alkyl group having 1 to 4 carbon atoms, R ²⁵ is A hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group which may have a substituent, an aralkyl group or a cyano group which may have a substituent, R ²⁶ and R ²⁷ are respectively Independently, the benzene ring which may have a substituent or the atomic group constituting the optionally substituted naphthalene ring, R ²⁸ and R ²⁹ each independently have a substituent. Or an aryl group or an alkyl group having 1 to 4 carbon atoms. However, at least one group of R ²¹ , R ²² , R ²³ and R ²⁴ is not a methyl group. R ²¹ and R ²² and / or R ²³ and R ²⁴ may be bonded to each other to form a 3- to 6-membered ring. ]

  According to the present invention, a method for producing an optical recording medium capable of forming a recording layer that is unlikely to deteriorate with time and having very little dissolution of the substrate during formation of the recording layer, a coating solution used therefor, and this method for production It becomes possible to provide the optical recording medium obtained by the above.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings as necessary. In addition, the same code | symbol is attached | subjected to the same element and the overlapping description is abbreviate | omitted. Also, the positional relationship such as up / down / left / right is based on the positional relationship of the drawings.

  The optical recording medium according to the embodiment includes a step of applying a coating liquid containing a solvent and a dye on a substrate. Hereinafter, the coating liquid used for this manufacturing method is demonstrated.

[solvent]
First, the solvent contained in the coating solution will be described. The solvent mainly contains the compound represented by the general formula (1), and preferably comprises the compound represented by the general formula (1). The solvent preferably does not contain at least tetrafluoropropanol (TFP), for example, 2,2,3,3-tetrafluoropropanol (2,2,3,3-TFP).

  The compound represented by the general formula (1) is represented by the following general formula (3a), the following general formula (3b), or the following general formula (3c). Compounds are preferred. These may be used alone or in combination.

In the formula (3a), R ³¹ represents an alkyl group having 1 to 4 carbon atoms (preferably a methyl group or an ethyl group), and R ³² represents an alkylene group having 1 to 4 carbon atoms (preferably an ethylene group, a methylmethylene group, Propylene group or methylethylene group). Moreover, in Formula (3b), ^R33 shows a methyl group or an ethyl group, ^R34 shows a C1-C4 alkylene group. Furthermore, in the formula (3c), R ³⁵ represents an alkylene group having 1 to 6 carbon atoms.

  Examples of the compound represented by the general formula (3a) include 2-methoxyethanol, 2-ethoxyethanol, 2-hydroxyethyl isopropyl ether, 2-hydroxyethyl propyl ether, 3-hydroxypropyl methyl ether, 1-methoxy-2. -Propanol, 3-hydroxypropyl ethyl ether, 2-hydroxyethyl butyl ether, 4-hydroxybutyl methyl ether, 3-hydroxypropyl ethyl ether, 2-hydroxy-1-methyl ethyl methyl ether, 2-hydroxy-1-methyl ethyl isopropyl Examples include ether, 2-hydroxy-2-methylethyl methyl ether, and 2-hydroxy-2-methylethyl isopropyl ether. Of these, 2-methoxyethanol, 2-ethoxyethanol or 1-methoxy-2-propanol is preferable.

  Examples of the compound represented by the general formula (3b) include acetol, acetoin, acetoethyl alcohol, 4-hydroxy-4-methyl-2-pentanone, and 4-hydroxy-4-methyl-2-pentanone. Is preferred. Furthermore, examples of the compound represented by the general formula (3c) include 3-methyl-1-pentyn-1-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-butyn-1-ol, 2-propyn-1-ol is mentioned.

[Dye]
Next, the pigment contained in the coating solution will be described. A pigment | dye contains the chelate compound of the compound represented by the said General formula (2), and an azo compound and a metal.

<Cyanine compounds>
The compound represented by the general formula (2) is classified as a so-called cyanine compound. In the compound represented by the general formula (2), R ²¹ , R ²² , R ²³ and R ²⁴ (hereinafter referred to as “R ^{21 to} R ²⁴ ”) are each independently a substituent. It may be a benzyl group or an alkyl group having 1 to 4 carbon atoms, and all of these are not methyl groups.

^The alkyl group having 1 to 4 carbon atoms constituting the group represented by R 21 ^{to R 24,} a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, s- butyl, t- butyl Group, isobutyl group and the like. Moreover, when both of R ²¹ and R ²² and / or R ²³ and R ²⁴ are each an alkyl group having 1 to 4 carbon atoms, carbons in the alkyl group are bonded to form a 3- to 6-membered ring. May be formed. In a preferred case, at least one of the groups represented by R ²¹ , R ²² , R ²³ and R ²⁴ is an optionally substituted benzyl group, more preferably a benzyl group.

R ²⁵ is preferably a hydrogen atom. Furthermore, R ²⁸ and R ²⁹ is an alkyl group having 1 to 4 carbon aryl group or C may have a substituent, may each be the same or different. Among ^{them, R 28} and ^{R 29,} preferable to be an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group.

Examples of the compound represented by the general formula (2) having such a structure include those shown below. ^Hereinafter, it will be explained by classifying each combination of groups represented by ^{R 26} and ^{R 27.} In addition, as a compound represented by the said General formula (2), the compound classified into the following can be selected arbitrarily and can be used.

(Compound in which both R ²⁶ and R ²⁷ are benzene rings)
First, examples of the compound in which both R ²⁶ and R ²⁷ are benzene rings which may have a substituent include those represented by the following general formula (4).

In the formula, R ²³ and R ²⁴ are as defined above, and R ⁴⁰ is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a halogen atom, a cyano group or a nitro group, R ⁴¹ shows the methyl group or the benzyl group which may have a substituent. As such a compound, for example, when R ⁴¹ is a methyl group, a combination in which either one of R ²³ and R ²⁴ is an alkyl group and the other is a benzyl group which may have a substituent is used. Or those in which both are alkyl groups having 1 to 4 carbon atoms and carbons are bonded to each other to form a 3- to 6-membered ring. For example, the following chemical formulas (5a) to (5d) Is preferred. In addition, when R ⁴¹ is a benzyl group which may have a substituent, a compound represented by the following chemical formula (5e), wherein R ²³ and R ²⁴ are benzyl groups which may have a substituent. Is preferred.

(Compound wherein R ²⁶ is a benzene ring and R ²⁷ is a naphthalene ring)
In the compound represented by the general formula (2), R ²⁶ is a benzene ring which may have a substituent, and R ²⁷ is a naphthalene ring which may have a substituent. The compound represented by following General formula (6) is mentioned.

In the formula, R ²³ and R ²⁴ have the same meanings as described above, R ⁶¹ represents an atomic group constituting a naphthalene ring which may have a substituent, R ⁶² represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, An alkoxy group having 1 to 3 carbon atoms, a halogen atom, a cyano group or a nitro group is shown. As the compound represented by the general formula (6), a combination in which both R ²³ and R ²⁴ are methyl groups, or a combination in which one is a methyl group and the other is an ethyl group is preferable. Examples of such a compound include compounds represented by the following chemical formulas (7a) to (7f).

The compound represented by the general formula (6), both of R ²³ and R ²⁴ is an alkyl group having 1 to 4 carbon atoms, form a 3-6 membered ring of carbon between each other Suitable compounds are also suitable. Examples of such a compound include compounds represented by the following chemical formula (8a) or (8b).

(Compound wherein R ²⁶ is a naphthalene ring and R ²⁷ is a benzene ring)
Among the compounds represented by the above general formula (2), R ²⁶ is a naphthalene ring which may have a substituent, and R ²⁷ is a benzene ring which may have a substituent. And a compound represented by the following general formula (9).

In the formula, R ²³ and R ²⁴ are as defined above, R ⁹¹ is an atomic group constituting a naphthalene ring which may have a substituent, R ⁹² is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, An alkoxy group having 1 to 3 carbon atoms, a halogen atom, a cyano group or a nitro group is shown. The compound represented by the general formula (9) is a combination in which both R ²³ and R ²⁴ are methyl groups, and a combination in which one is a methyl group and the other is an ethyl group or an n-propyl group. Or a combination in which both are ethyl groups is preferred. Examples of such compounds include compounds represented by the following chemical formulas (10a) to (10e).

The compound represented by the above general formula (9), a one methyl group of R ²³ and R ^24, also the other those combinations are benzyl group that may have a substituent preferable. Examples of such a compound include compounds represented by the following chemical formula (11a) or (11b).

Furthermore, as the compound represented by the general formula (9), a compound in which both R ²³ and R ²⁴ are benzyl groups optionally having a substituent is also suitable. An example of such a compound is a compound represented by the following chemical formula (12).

(Compound in which both R ²⁶ and R ²⁷ are naphthalene rings)
Among the compounds represented by the general formula (2), as a compound in which both of R ²⁶ and R ²⁷ are a naphthalene ring optionally having a substituent, a compound represented by the following general formula (13) Is mentioned.

In the formula, R ²³ and R ²⁴ are as defined above, and R ¹³¹ and R ¹³² represent an atomic group constituting a naphthalene ring which may have a substituent. As a compound having such a structure, a combination in which both R ²³ and R ²⁴ are methyl groups, a combination in which one is a methyl group and the other is a benzyl group which may have a substituent, or , Both are alkyl groups having 1 to 4 carbon atoms, and a combination in which the carbon atoms are bonded to form a 3- to 6-membered ring is preferable. Of these, a combination in which both are methyl groups, or a combination forming a 3- to 6-membered ring is particularly preferable. Examples of such compounds include compounds represented by the following chemical formulas (14a) to (14c).

  As the compound to be contained as the pigment, among the compounds described above, the compound represented by the chemical formula (12) or the compound represented by the chemical formula (14a) is particularly preferable. These compounds are excellent in the property of dispersing heat after heating. Therefore, by using a coating solution containing these, it is possible to obtain an optical recording medium that hardly causes thermal interference.

The pigment | dye contained in a coating liquid contains the cyanine type compound mentioned above and the counter ion (counter anion) of the said compound. Specific examples of such counter anions include halide ions (Cl ⁻ , Br ⁻ , I ⁻ etc.), ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , VO ₃ ⁻ , VO ₄ ³⁻ , WO ₄ ²⁻ , CH ₃ SO ₃ ⁻ , CF ₃ COO ⁻ , CH ₃ COO ⁻ , HSO ₄ ⁻ , CF ₃ SO ₃ ⁻ , p-toluenesulfonate ion (PTS ⁻ ), p-methyl triphenylphenylsulfonate ion (PFS ⁻ ) and the like. Of these, ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ^{− and the} like are preferable.

<Chelate compound>
The coloring matter contained in the coating solution contains a chelate compound (azo metal complex) of an azo compound and a metal in addition to the above-described cyanine compound. Examples of such chelate compounds include metal chelate compounds formed by coordination of an azo compound having an azo group substituted with an aromatic ring with a metal. Such a compound is also called an azo dye or an azo dye. Examples of the azo compound constituting this chelate compound include compounds represented by the following general formula (15).

In such a compound, R ¹⁵¹ and R ¹⁵² are aromatic rings, and at least one of them is an aromatic ring having a substituent that can be coordinated to a metal atom, or a nitrogen-containing compound that has a nitrogen atom that can be coordinated to a metal atom Heteroaromatic ring. R ¹⁵¹ and R ¹⁵² may be the same or different. Here, the substituent capable of coordinating to the metal atom and the nitrogen atom capable of coordinating to the metal atom are adjacent to the position substituted with the azo group (for example, ortho position in the case of a benzene ring). It is preferable.

The aromatic ring constituting R ¹⁵¹ and R ¹⁵² may be a single ring, a condensed polycyclic ring or a polycyclic ring assembly. Examples of such an aromatic ring include a benzene ring, naphthalene ring, pyridine ring, thiazole ring, benzothiazole ring, oxazole ring, benzoxazole ring, quinoline ring, imidazole ring, pyrazine ring, and pyrrole ring. Among these, a benzene ring, a pyridine ring, a quinoline ring, and a thiazole ring are particularly preferable.

Examples of the substituent capable of coordinating to a metal atom include a group having active hydrogen. Examples of the group having active hydrogen include —OH, —SH, —NH ₂ , —COOH, —CONH ₂ , —SO ₂ NH ₂ , —SO ₃ H, —NHSO ₂ CF _{3, and the} like. Among these, -OH is particularly preferable.

R ¹⁵¹ and R ¹⁵² may have other substituents in addition to the above. The substituents that R ¹⁵¹ and R ¹⁵² have may be the same or different. When they are different, R ¹⁵¹ is a nitro group, a halogen atom (for example, chlorine atom, bromine atom, etc.), a carboxyl group, a sulfo group, a sulfamoyl group and an alkyl group (preferably having 1 to 4 carbon atoms, more preferably a methyl group). And R ¹⁵² is preferably an amino group (a dialkylamino group having 2 to 8 carbon atoms in total, for example, a dimethylamino group, a diethylamino group, a methylethylamino group, a methyl group). Propylamino group, dibutylamino group, hydroxyethylmethylamino group and the like), alkoxy group (preferably having 1 to 4 carbon atoms, such as methoxy group), alkyl group (preferably carbon number) 1-4, more preferably a methyl group), an aryl group (monocyclic is preferable, for example, a phenyl group, And a phenyl group), preferably has at least one group selected from the group consisting of carboxyl group and sulfo group. Incidentally, it is preferable that the substituents R ¹⁵¹ are in a meta or para to the azo group, and more preferably in the meta position.

As the metal constituting the chelate compound (center metal), transition metals such as Co, Mn, Ti, V, Ni, Cu, Zn, Mo, W, Ru, Fe, Pd, Pt, and Al are preferable. Alternatively, V, Mo, and W, which is the oxide ions ^{respectively, VO 2+, VO 3+, MoO} 2+, MoO 3+, may have as ^{WO 3+} like. Of these, VO ²⁺ , VO ³⁺ , Co, Ni and Cu are particularly preferable.

  In these chelate compounds, usually, an azo compound as described above is used as a tridentate ligand and a coordination bond is formed with a metal. In addition, when the azo compound has a substituent having active hydrogen, the active hydrogen is usually eliminated to form a tridentate ligand.

Such a chelate compound may be neutral as a whole, or may be an anion or a cation. When the chelate compound is an anion, it forms a salt with its counter cation. Examples of the counter cation include metal cations such as Na ⁺ , Li ⁺ , and K ⁺ , ammonium, and tetraalkylammonium. Alternatively, the above-described cyanine compound may be used as a counter cation to form a salt.

  Specific examples of the chelate compound include those described in Tables 1 to 6 below. These can be used alone or in combination. In the chelate compounds shown in Tables 1 to 6, two azo compounds are coordinated with one central metal element. In the table, two types of azo compound and central metal respectively indicate that they are contained at a molar ratio of 1: 1. These chelate compounds can be obtained by synthesis according to known methods (see, for example, Furukawa, Anal. Chim. Acta., 140, p. 289, 1982).

  As described above, the coating liquid used in the manufacturing method according to the embodiment contains the above-described cyanine compound and chelate compound as a pigment, when suitable. In addition, in this coating liquid, you may contain other types of pigment | dyes in addition to these. Examples of such other dyes include subphthalocyanine dyes, formazan dyes, rhodamine dyes, and triphenylmethane dyes. When these other pigments are contained, the cyanine pigment is preferably blended so that the content of the cyanine pigment is 30 to 90 mol% of the whole pigment. When the content of the cyanine dye is less than 30 mol%, it is difficult to sufficiently suppress thermal interference in the optical recording medium.

  As for the content of the pigment in the coating solution, the total mass of the pigment with respect to the total amount of the coating solution is preferably 0.1 to 10% by mass, more preferably 0.3 to 5% by mass, and further preferably 0.5. It is preferable to be set to ˜3 mass%. When the total content of the dyes is less than 0.1% by mass, it tends to be difficult to obtain a recording layer in which pits can be favorably formed by laser irradiation. On the other hand, if it exceeds 10% by mass, the pigment may be deposited during coating. The dye thus deposited tends to be a defect in the recording layer. In addition to these, for example, a binder, a dispersant, a stabilizer, and the like may be appropriately contained in the coating solution.

[Method of manufacturing optical recording medium]
An optical recording medium manufacturing method according to a preferred embodiment includes a step of applying the coating liquid of the above-described embodiment onto a substrate. First, a preferred embodiment of an optical recording medium obtained by such a manufacturing method will be described. FIG. 1 is a diagram schematically showing a cross-sectional structure of an optical recording medium manufactured by the manufacturing method of the embodiment. An optical recording medium 10 shown in FIG. 1 is a write-once digital versatile disc that complies with the DVD standard, and is capable of recording / reproducing with light having a short wavelength in the vicinity of 620 to 690 nm.

  The optical recording medium 10 includes a single-sided optical recording medium 31 in which a substrate 12, a recording layer 13, a reflective layer 14, and a protective layer 15 are laminated in this order, and a substrate 22, a recording layer 23, a reflective layer 24, and a protective layer 25 in this order. The laminated single-sided optical recording medium 32 has a structure in which the protective layers 15 and 25 are bonded to each other via an adhesive layer 50 so as to face each other. That is, the optical recording medium 1 includes the substrate 12, the recording layer 13, the reflective layer 14, the protective layer 15, the adhesive layer 50, the protective layer 25, the reflective layer 24, the recording layer 23, and the substrate 22 in this order from the lower side in the figure. It has a laminated structure. Groove-shaped grooves 123 and 223 are formed on the surfaces of the substrates 12 and 22 facing the recording layers 13 and 23, respectively.

  Hereinafter, a method for manufacturing the optical recording medium 10 having such a configuration will be described. As described above, the optical recording medium 10 is formed by bonding the single-sided optical recording medium 31 and the single-sided optical recording medium 32, and each single-sided optical recording medium can be manufactured in the same manner. Here, a method for manufacturing the single-sided optical recording medium 31 will be described as an example.

  In manufacturing the single-sided optical recording medium 31, first, the substrate 12 is prepared. The substrate 12 has a disk shape with a diameter of about 64 to 200 mm and a thickness of about 0.6 mm. As such a substrate 12, when writing and reading to and from the optical recording medium 10, in order to irradiate the recording layer 13 provided inside the substrate 12 with recording light and reproducing light, Those that are substantially transparent are preferred. More specifically, the transmittance of the substrate 12 with respect to recording light and reproducing light is preferably 88% or more. As a material of the substrate 12 that satisfies such conditions, a resin or glass that satisfies the above-described conditions regarding transmittance is preferable, and among them, a thermoplastic resin such as polycarbonate resin, acrylic resin, amorphous polyolefin, TPX, and polystyrene resin is particularly preferable. .

  A groove-shaped groove 123 is formed on the surface of the substrate 12 facing the recording layer 13. The groove 123 is a continuous groove having a spiral shape when the substrate is viewed from above. The groove 123 preferably has a depth of 60 to 200 nm, a width of 200 to 500 nm, and a groove pitch of 0.6 to 1.0 μm. When the groove 123 has such a configuration, a good tracking signal can be obtained without reducing the reflection level in the groove.

  The groove 123 can be formed at the same time as the substrate 12 is molded by performing injection molding or the like using the resin. Moreover, after manufacturing the flat board | substrate 12, you may form by forming the resin layer which has the recessed part used as the groove | channel 123 by 2P method etc., and making it the composite substrate of the board | substrate 12 and this resin layer.

  Next, the recording layer 13 is formed by applying the coating liquid of the above-described embodiment on the surface of the substrate 12 on which the groove 123 is formed. In forming the recording layer 13, after applying the coating solution, a drying step of removing the solvent may be performed as necessary. The coating liquid can be applied by spin coating, gravure coating, spray coating, dip coating, or the like. Among these, a spin coating method that can easily and uniformly apply a uniform thickness is preferable.

  The coating liquid is preferably applied so that the thickness of the recording layer 13 after drying is 50 to 200 nm, and more preferably 70 to 150 nm. If the thickness of the recording layer 13 is outside this range, the reflectance with respect to the reproduction light decreases, and it tends to be difficult to perform good reproduction.

  The recording layer 13 is mainly composed of a dye containing a compound represented by the general formula (1). In the recording layer 13 thus formed, the compound represented by the general formula (1), which is a solvent contained in the coating solution, remains even after the drying step. Many. In this case, the content of the compound in the recording layer 13 is often 30 to 50 μg with respect to one recording layer 13. Even if the solvent remains to this extent, the deterioration of the characteristics of the recording layer 13 is extremely small. Further, when the content is reduced to 0 to 30 μg / sheet, the effect of the residual solvent on the recording layer 13 becomes a level at which substantially no effect is seen.

  It is preferable that the extinction coefficient (imaginary part k of the complex refractive index) of the recording layer 13 thus formed with respect to the recording light and the reproduction light is 0 to 0.20. If the extinction coefficient exceeds 0.20, sufficient reflectance tends to be difficult to obtain. The refractive index of the recording layer 13 (real part n of the complex refractive index) is preferably 1.8 or more. When the refractive index is less than 1.8, the degree of signal modulation tends to be small. The upper limit of the refractive index is not particularly limited, but is usually about 2.6 for the convenience of organic dye synthesis.

  Here, the extinction coefficient and refractive index of the recording layer 13 can be obtained according to the following procedure. First, a recording sample is provided on a predetermined transparent substrate at a thickness of about 40 to 100 nm to prepare a measurement sample, and then the reflectance of the measurement sample through the substrate or the reflectance from the recording layer side is measured. Desired. In this case, the reflectance is measured by specular reflection (about 5 °) using the wavelength of the recording / reproducing light. Further, the transmittance of the sample is measured. From these measured values, the extinction coefficient and the refractive index can be calculated according to the method described in, for example, Kyoritsu Zensho “Optics”, Kozo Ishiguro, pages 168 to 178.

  After the recording layer 13 is formed in this way, the reflective layer 14 is formed on the surface of the recording layer 13 opposite to the substrate 12. The reflective layer 14 can be formed by using a highly reflective metal or alloy and depositing these by vapor deposition, sputtering, or the like. Examples of the metal and alloy for forming the reflective layer 14 include gold (Au), copper (Cu), aluminum (Al), silver (Ag), and AgCu. The reflective layer 14 is preferably formed so as to have a thickness of 50 to 120 nm.

  Thereafter, a coating solution for forming a protective layer containing a material such as an ultraviolet curable resin is applied on the surface of the reflective layer 14 opposite to the substrate 12, and the coating layer is dried as necessary to form the protective layer 15. The single-sided optical recording medium 31 is obtained. The protective layer 15 thus formed has, for example, a layer shape or a sheet shape, and the thickness is preferably 0.5 to 100 μm. The coating liquid for forming the protective layer can be applied by spin coating, gravure coating, spray coating, dip coating or the like, as in the case of forming the recording layer 13.

  The single-sided optical recording medium 32 can be obtained in the same manner as the single-sided optical recording medium 31 described above. Then, the two obtained single-sided optical recording media 31 and 32 are bonded using a known adhesive so that the protective layers 15 and 25 face each other. Thereby, the optical recording medium 10 in which the single-sided optical recording medium 31 and the single-sided optical recording medium 32 are bonded via the adhesive layer 50 is obtained.

  The optical recording medium obtained by the production method of the present invention does not necessarily have to be a mode in which two single-sided optical recording media as described above are bonded together, and may be a single-sided recording medium alone. FIG. 2 is a diagram showing a cross-sectional structure of an optical recording medium having such a mode, that is, an optical recording medium having a recording layer on one side of a substrate. The optical recording medium 1 shown in FIG. 2 has a structure in which a recording layer 3, a reflective layer 4, a protective layer 5, an adhesive layer 7, and a dummy substrate 6 are laminated on a substrate 2 in this order. ing. A groove-like groove is formed on the surface of the substrate 2 facing the recording layer 3.

  Thus, in the optical recording medium 1, the dummy substrate 6 is bonded to the protective layer 5 via the adhesive layer 7, so that sufficient strength is ensured in the form of a single-sided optical recording medium. It has become. The optical recording medium 1 having the above configuration is formed on the protective layer 5 after forming a laminate including the substrate 2, the recording layer 3, the reflective layer 4, and the protective layer 5 in the same manner as the production of the single-sided optical recording medium 31 described above. It can be formed by adhering the dummy substrate 6 via the adhesive layer 7.

  Further, the above-described optical recording medium 1 or the single-sided recording media 31 and 32 in the optical recording medium 10 do not have to be in a form in which a single recording layer is provided on each substrate, and a plurality of layers are provided. Form may be sufficient. In this case, if a plurality of recording layers provided on the substrate contain different dyes, information can be recorded on each recording layer by using a plurality of recording / reproducing lights having the same or different wavelengths.・ Playback can be performed. In such an optical recording medium, a translucent reflective film that is transparent to recording / reproducing light may be provided on each recording layer.

[Preparation of coating solution]
(Examples 1-8, Comparative Examples 1-3)
As the dye, the compound represented by the above chemical formula (14a) which is a cyanine compound and the compound of the above A5 which is a chelate compound are respectively added to the solvents shown in Table 7 so that the molar ratio thereof is 70:30. It melt | dissolved and the coating liquid of Examples 1-8 and Comparative Examples 1-3 was prepared. In addition, the pigment | dye density | concentration in a table | surface has shown the total molar amount of a cyanine compound and a chelate compound with respect to the total molar amount of a coating liquid.

［光記録媒体の製造］

[Manufacture of optical recording media]

Example 9
The coating liquid of Example 1 was applied to a thickness of 150 nm on a polycarbonate resin substrate having a diameter of 120 mm and a thickness of 0.6 mm by spin coating, and then dried to form a recording layer.

  Next, a reflective layer made of Ag was formed on the recording layer by sputtering. The thickness of the reflective layer was set to 100 nm. Next, an ultraviolet curable acrylic resin was applied on the reflective layer so as to have a thickness of 5 μm by spin coating, and then cured by irradiating with ultraviolet rays to form a protective layer. Then, a dummy substrate (a polycarbonate resin substrate having a thickness of 0.6 mm) was bonded onto the protective layer via an adhesive layer to obtain an optical recording medium having a structure shown in FIG.

(Examples 10 to 16, Comparative Examples 4 to 6)
Examples 10 to 16 and Comparative Examples 4 to 6 were the same as Example 9 except that the coating liquids of Examples 2 to 8 and Comparative Examples 1 to 3 were used in place of the coating liquid of Example 1. An optical recording medium was manufactured.

[Characteristic evaluation]
(Evaluation of the influence on the substrate when applying the coating solution)
In the production of the optical recording media of Examples 9 to 16 and Comparative Examples 4 to 6, when applying the coating liquid corresponding to each Example or Comparative Example to the substrate, it is visually checked whether the substrate is dissolved in the coating liquid. Confirmed. The obtained results are shown in Table 8. In the table, those that did not cause dissolution were indicated by ◯.

(Measurement of reflectance change rate)
The optical recording media of Examples 9 to 16 and Comparative Examples 4 to 6 were irradiated with a laser having a wavelength of 650 nm, and the irradiated laser (irradiated light) detected light (reflected light) reflected by the optical recording medium. The reflectance was measured. Next, these optical recording media were exposed to an environment at a temperature of 80 ° C. and a relative humidity of 80% for 50 hours, and then the reflectance was measured in the same manner as described above. Based on these results, the reflectance change rate (%) before and after exposure to the environment was calculated for each optical recording medium. Table 8 shows the obtained results.

(Measurement of change rate of jitter)
For the recording layers of the optical recording media of Examples 9 to 16 and Comparative Examples 4 to 6, using a laser with a wavelength of 655 nm, the linear velocity was 3.5 m / s (corresponding to the same speed) or 28.0 m / s (8 times speed). The signal was recorded respectively, and then the jitter was measured using a laser having a wavelength of 650 nm and reproducing at a linear velocity of 3.5 m / s. After that, these optical recording media were exposed to an environment at a temperature of 80 ° C. and a relative humidity of 80% for 50 hours, and then jitter was measured when reproduced under the same conditions as described above. At this time, the lens hole diameter NA was set to 0.60. Based on these values, the jitter change rate (%) before and after exposure to the environment was calculated for each optical recording medium. Table 8 shows the obtained results. Since there was no significant difference in the rate of change in jitter between recording at the normal speed and recording at the 8 * speed, Table 8 shows only the results for the 8 * speed.

  From Table 8, the optical recording media (Examples 9 to 16) obtained by using the coating liquids (Examples 1 to 8) containing the compound represented by the general formula (1) are coated without such a solvent. It was found that the reflectance change and the jitter change were small as compared with the optical recording media (Comparative Examples 4 to 6) obtained using the liquids (Comparative Examples 1 to 3). From this, it was confirmed that the optical recording medium obtained by the production method of the present invention hardly deteriorates with time. Further, the substrate was hardly dissolved when the coating solution was applied.

It is a figure which shows typically the cross-sectional structure of the optical recording medium manufactured by the manufacturing method of embodiment. It is a figure which shows the cross-section of an optical recording medium provided with a recording layer on the single side | surface of a board | substrate.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical recording medium, 2 ... Substrate, 3 ... Recording layer, 4 ... Reflective layer, 5 ... Protective layer, 6 ... Dummy substrate, 7 ... Adhesive layer, 10 ... Optical recording medium, 12 ... Substrate, 13 ... Recording layer , 14 ... reflective layer, 15 ... protective layer, 22 ... substrate, 23 ... recording layer, 24 ... reflective layer, 25 ... protective layer, 31, 32 ... single-sided optical recording medium.

Claims (5)

A step of applying a coating solution containing a solvent and a dye dissolved in the solvent on the substrate;
As the solvent, a solvent containing a compound represented by the following general formula (1) is used,
As the pigment, a pigment containing a compound represented by the following general formula (2) and a chelate compound of an azo compound and a metal is used.
A method of manufacturing an optical recording medium.

[In Formula (1), R ¹¹ is a monovalent hydrocarbon group having a carbon-carbon triple bond, an alkoxy group having 1 to 4 carbon atoms, or an acyl group having 1 to 5 carbon atoms, and R ¹² is carbon number 1 Represents an alkylene group of ~ 8. In formula (2), R ²¹ , R ²² , R ²³ and R ²⁴ are each independently a benzyl group which may have a substituent or an alkyl group having 1 to 4 carbon atoms, R ²⁵ is A hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group which may have a substituent, an aralkyl group or a cyano group which may have a substituent, R ²⁶ and R ²⁷ are respectively Independently, the benzene ring which may have a substituent or the atomic group constituting the optionally substituted naphthalene ring, R ²⁸ and R ²⁹ each independently have a substituent. Or an aryl group or an alkyl group having 1 to 4 carbon atoms. However, at least one group of R ²¹ , R ²² , R ²³ and R ²⁴ is not a methyl group. R ²¹ and R ²² and / or R ²³ and R ²⁴ may be bonded to each other to form a 3- to 6-membered ring. ]   2. The method for producing an optical recording medium according to claim 1, wherein the solvent does not contain tetrafluoropropanol. In the compound represented by the general formula (2), at least one of R ²¹ , R ²² , R ²³ and R ^{24 is} a benzyl group which may have a substituent. The method for producing an optical recording medium according to claim 1. A coating liquid for forming a recording layer of an optical recording medium,
Containing a solvent and a dye dissolved in the solvent,
The solvent contains a compound represented by the following general formula (1),
The dye includes a compound represented by the following general formula (2) and a chelate compound of an azo compound and a metal.
A coating liquid characterized by that.

[In Formula (1), R ¹¹ is a monovalent hydrocarbon group having a carbon-carbon triple bond, an alkoxy group having 1 to 4 carbon atoms, or an acyl group having 1 to 5 carbon atoms, and R ¹² is carbon number 1 Represents an alkylene group of ~ 8. In formula (2), R ²¹ , R ²² , R ²³ and R ²⁴ are each independently a benzyl group which may have a substituent or an alkyl group having 1 to 4 carbon atoms, R ²⁵ is A hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group which may have a substituent, an aralkyl group or a cyano group which may have a substituent, R ²⁶ and R ²⁷ are respectively Independently, the benzene ring which may have a substituent or the atomic group constituting the optionally substituted naphthalene ring, R ²⁸ and R ²⁹ each independently have a substituent. Or an aryl group or an alkyl group having 1 to 4 carbon atoms. However, at least one group of R ²¹ , R ²² , R ²³ and R ²⁴ is not a methyl group. R ²¹ and R ²² and / or R ²³ and R ²⁴ may be bonded to each other to form a 3- to 6-membered ring. ] A substrate, and a recording layer formed on the substrate,
The recording layer contains a compound represented by the following general formula (1), a compound represented by the following general formula (2), and a chelate compound of an azo compound and a metal,
An optical recording medium characterized by the above.

[In Formula (1), R ¹¹ is a monovalent hydrocarbon group having a carbon-carbon triple bond, an alkoxy group having 1 to 4 carbon atoms, or an acyl group having 1 to 5 carbon atoms, and R ¹² is carbon number 1 Represents an alkylene group of ~ 8. In formula (2), R ²¹ , R ²² , R ²³ and R ²⁴ are each independently a benzyl group which may have a substituent or an alkyl group having 1 to 4 carbon atoms, R ²⁵ is A hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, an aryl group which may have a substituent, an aralkyl group or a cyano group which may have a substituent, R ²⁶ and R ²⁷ are respectively Independently, the benzene ring which may have a substituent or the atomic group constituting the optionally substituted naphthalene ring, R ²⁸ and R ²⁹ each independently have a substituent. Or an aryl group or an alkyl group having 1 to 4 carbon atoms. However, at least one group of R ²¹ , R ²² , R ²³ and R ²⁴ is not a methyl group. R ²¹ and R ²² and / or R ²³ and R ²⁴ may be bonded to each other to form a 3- to 6-membered ring. ]

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