JP2005319728A - Optical recording medium, reproducing method and optical recording device employing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording medium or the like which can be applied to a write-once-read many DVD disk system employing a semiconductor laser with an oscillation wavelength on a short-wavelength side in comparison with a conventional optical recording medium, and reduces dependency on a wavelength shift of the semiconductor laser. <P>SOLUTION: The optical recording medium is provided with a substrate and at least a recording layer on the substrate, wherein the recording layer at least contains a formazan metal chelate compound with a maximum absorption wavelength of an absorption spectrum of ≥500 nm to <650 nm (A), a squalilium compound with a maximum absorption wavelength of an absorption spectrum of ≥500 nm to <650 nm (B), and a compound with a maxim absorption wavelength of an absorption spectrum of ≥650 nm to <800 nm. The compound of component (C) is preferably a mode of at least one type selected from among the formazan metal chelate compound, a pentamethine cyanin compound, a phthalocyanine compound and a diarylamine compound. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical recording medium (hereinafter also referred to as “optical information recording medium” or “information recording medium”) suitable for a write-once DVD disk system that is less dependent on the wavelength shift of a semiconductor laser, The present invention relates to a recording / reproducing method and an optical recording apparatus using a recording medium.

  Currently, a write-once DVD medium is being developed as a next-generation large-capacity optical disk, and further increases in recording capacity are being studied. Therefore, with the aim of increasing the recording capacity, development of recording materials for recording pit miniaturization, adoption of image compression technology represented by Moving Picture Experts Group-2 (MPEG2), and semiconductor laser for reading recording pits Technological developments such as shortening the wavelength of (LD) are underway.

Until now, only 670 nm band AlGaInP semiconductor lasers have been commercialized as bar code readers and measuring instruments as semiconductor lasers in the red wavelength region. However, as the density of optical discs increases, red lasers are being used in earnest in the optical storage market. In the case of DVD drives, the light source is standardized with a wavelength of a semiconductor laser in the 630 to 690 nm band.
On the other hand, a read-only DVD-ROM drive is commercialized with a wavelength of about 650 nm. Under such circumstances, the most preferable write-once DVD medium is a medium that can be recorded and reproduced at a wavelength of 630 to 690 nm. Many dye-based materials used for these have been proposed. For example, a polymethine dye or a polymethine dye and a light stabilizer used as a recording material (see Patent Document 1), tetraazaporphyrin (porphyrazine). ) Using a dye as a recording material (see Patent Document 2), using a cyanine dye and an azo metal chelate dye (salt-forming dye) as a recording material (see Patent Document 3), using an azo metal chelate dye as a recording material (See Patent Documents 4 and 5), one using a formazan metal chelate dye as a recording material (see Patent Document 6), one using a dipyrromethene metal chelate dye as a recording material (see Patent Document 7), and using a squarylium compound as a recording material. (Refer to Patent Document 8), squarylium metal chelate compound Such as those used as a recording material (see Patent Document 9) and the like.

  However, in order to obtain the high reflectance characteristic of the dye-based media, these dye-based materials are arranged so that the long wavelength end of the absorption band of the absorption spectrum becomes the recording and reproducing wavelength as shown in FIG. There is a problem that it is designed and has a large wavelength dependency. In addition, it is known that the oscillation wavelength of a semiconductor laser used in a recordable DVD drive or the like varies depending on the use environment. In particular, when placed in a high temperature environment, the oscillation wavelength shifts to the long wavelength side, so that the absorption coefficient k of the dye material used in the recording layer becomes small and the recording sensitivity becomes insufficient. There is.

  Therefore, an optical recording medium that is suitable for a write-once DVD disc system using a semiconductor laser having an oscillation wavelength on the short wavelength side, is less dependent on the wavelength shift of the semiconductor laser, and has sufficiently satisfactory recording performance is desired. However, the present situation is that a satisfactory optical recording medium is not yet provided.

Japanese Patent Laid-Open No. 10-181211 JP 2002-283721 A International Publication No. 98/029257 Pamphlet JP 2000-127625 A JP-A-11-310728 JP 2001-023235 A JP-A-10-226172 JP 2001-322356 A JP 2002-370451 A

  This invention is made | formed in view of this present condition, and makes it a subject to solve the said various problems in the past and to achieve the following objectives. That is, the present invention can be applied to a write-once DVD disc system using a semiconductor laser having an oscillation wavelength on the short wavelength side as compared with a conventional optical recording medium, and is less dependent on the wavelength shift of the semiconductor laser. It is an object to provide a medium, a recording / reproducing method using the optical recording medium, and an optical recording apparatus.

  As a result of intensive studies by the present inventors in order to solve the above problems, a mixed dye material of a formazan metal chelate compound and a squarylium compound having a maximum absorption wavelength of 500 nm or more and less than 650 nm, which is a recording material of a conventional write once DVD medium In contrast, by adding a compound having a maximum absorption wavelength of 650 nm or more and 800 nm or less (preferably a formazan metal chelate compound, a pentamethine cyanine compound, a phthalocyanine compound, or a diarylamine compound), the dependency on the wavelength shift of the semiconductor laser is small. It has been found that an optical recording medium can be obtained.

ただし、前記構造式（１）中、環Ｘは、隣接する窒素原子と炭素原子が一緒になって形成される複素環を表し、該複素環は更に置換基により置換されていてもよく、他の環と縮合していてもよい。Ｚ_０は、環Ｘを構成する原子を表す。Ａは、アルキル基、アリール基、アルキルカルボニル基、アリールカルボニル基、アルケニル基、アルコキシカルボニル基、及び複素環基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｂは、アルキル基、アルケニル基、及びアリール基のいずれかを表し、これらは更に置換基で置換されていてもよい。

ただし、前記構造式（２）中、環Ｙ及び環Ｚは、互いに同一であってもよいし、異なっていてもよく、隣接する窒素原子と炭素原子が一緒になって形成される複素環を表し、該複素環は更に置換基により置換されていてもよく、他の環と縮合していてもよい。Ｚ_１及びＺ_２は、それぞれ環Ｙ及び環Ｚを構成する原子を表す。Ａ_１及びＡ_２は、互いに同一であってもよいし、異なっていてもよく、アルキル基、アリール基、アルキルカルボニル基、アリールカルボニル基、アルケニル基、アルコキシカルボニル基、及び複素環基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｂ_１及びＢ_２は、互いに同一であってもよいし、異なっていてもよく、アルキレン基、アルケニレン基、又はアリーレン基を表し、これらは更に置換基で置換されていてもよい。Ｗは、−ＣＨ_２−、又は−ＳＯ_２−を表す。ｎは、０又は１の整数である。
＜５＞ 金属及び金属化合物のいずれかが、バナジウム、マンガン、鉄、コバルト、ニッケル、銅、亜鉛、パラジウム、及び該金属の酸化物、並びに該金属のハロゲン化物から選択される少なくとも１種である前記＜４＞に記載の光記録媒体である。
＜６＞ （Ｂ）成分が、下記構造式（３）及び下記構造式（４）のいずれで表されるスクアリリウム化合物である前記＜１＞から＜５＞のいずれかに記載の光記録媒体である。

ただし、前記構造式（３）中、Ｒ^１及びＲ^２は、互いに同一であってもよいし、異なっていてもよく、水素原子、アルキル基、アラルキル基、アリール基、及び複素環基のいずれかを表し、これらは更に置換基で置換されていてもよく、Ｒ^１及びＲ^２は隣接する窒素原子と一緒になって置換基を有していてもよい複素環を形成していてもよい。Ｒ^３は、下記構造式（３−１）及び下記構造式（３−２）のいずれかで表される置換基を表す。

ただし、前記構造式（３−１）中、Ｒ^４及びＲ^５は、互いに同一であってもよいし、異なっていてもよく、水素原子、又は置換基を有していてもよいアルキル基を表し、これらは隣接する窒素原子と一緒になって置換基を有していてもよい複素環を形成してもよい。Ｒ^６、Ｒ^７、Ｒ^８及びＲ^９は、互いに同一であってもよいし、異なっていてもよく、水素原子、ハロゲン原子、水酸基、アルキル基、及びアルコキシ基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｒ^４及びＲ^６又はＲ^５及びＲ^７は、隣接するＮ−Ｃ−Ｃと一緒になって置換基を有していてもよい複素環を形成してもよい。

ただし、前記構造式（３−２）中、Ｑ_１は、炭素原子及び窒素原子のいずれかを表す。Ｒ^１０及びＲ^１１は、互いに同一であってもよいし、異なっていてもよく、水素原子、アルキル基、アリール基、及びアラルキル基のいずれかを表し、これらは更に置換基により置換されていてもよい。ただし、Ｑ_１が窒素原子である場合、Ｒ^１１は存在しない。
Ｒ^１２は、水素原子、アルキル基、アリール基、及びアラルキル基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｒ^１３及びＲ^１４は、互いに同一であってもよいし、異なっていてもよく、水素原子、ハロゲン原子、アルキル基、及びアルコキシ基のいずれかを表し、これらは更に置換基により置換されていてもよく、隣接する２つの炭素原子と一緒になって置換基を有していてもよい複素環、置換基を有していてもよい脂環式炭化水素環、又は置換基を有していてもよい芳香族環を形成していてもよい。

ただし、前記構造式（４）中、Ｑ_２は、炭素原子及び窒素原子のいずれかを表す。Ｒ^１５は、水素原子、アルキル基、アリール基、及び複素環基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｒ^１６は、水素原子、ハロゲン原子、アミノ基、アルキル基、アルコキシ基、アラルキル基、アリール基、及び複素環基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｒ^１７及びＲ^１８は、互いに同一であってもよいし、異なっていてもよく、水素原子、アルキル基、アリール基、及びアラルキル基のいずれかを表し、これらは更に置換基により置換されていてもよく、隣接する炭素原子と一緒になって置換基を有していてもよい複素環、又は置換基を有していてもよい脂環式炭化水素環を形成してもよい。ただし、Ｑ_２が窒素原子の場合、Ｒ^１８は存在しない。
Ｒ^１９は、水素原子、アルキル基、アラルキル基、及びアリール基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｒ^２０は、ハロゲン原子、ニトロ基、シアノ基、アルキル基、アラルキル基、アリール基、及びアルコキシ基のいずれかを表し、これらは更に置換基により置換されていてもよい。ｎは、０〜４の整数を表し、ｎが２〜４の場合、Ｒ^２０は互いに同一であってもよいし、異なっていてもよく、互いに隣り合う２つのＲ^２０が隣接する２つの炭素原子と一緒になって置換基を有していてもよい芳香族環を形成していてもよい。
＜７＞ （Ｃ）成分が、下記構造式（５）で表されるペンタメチンシアニン化合物である前記＜１＞から＜６＞のいずれかに記載の光記録媒体である。

ただし、前記構造式（５）中、Ｒ^２１は、水素原子、ハロゲン原子、アルキル基、及びアルケニル基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｒ^２２及びＲ^２３は、互いに同一であってもよいし、異なっていてもよく、置換基を有していてもよいアルキル基を表す。Ｑ⁻は、アニオンを表す。
＜８＞ （Ｃ）成分が、下記構造式（６）で表されるフタロシアニン化合物である前記＜１＞から＜６＞のいずれかに記載の光記録媒体である。

ただし、前記構造式（６）中、Ｒ^２４〜Ｒ^２７は、互いに同一であってもよいし、異なっていてもよく、水素原子、アルキル基、アリール基、アルケニル基、アルキルスルフィニル基、アリールスルフィニル基、アルキルスルホニル基、アリールスルホニル基、アルキルオキシスルホニル基、アリールオキシスルホニル基、アルコキシ基、アリールカルボニルオキシ基、及び複素環基のいずれかを表し、これらは更に置換基により置換されていてもよい。ｑ１〜ｑ４は、０〜４の整数を表し、ｑ１〜ｑ４が２〜４の場合、各Ｒ^２４〜Ｒ^２７は互いに同一であってもよいし、異なっていてもよい。Ｍ_１は、２個の水素原子、金属原子、金属化合物、半金属原子、及び半金属化合物のいずれかを表す。
＜９＞ Ｍ_１が、Ｖ＝Ｏ及びＬ_１−Ｓｉ−Ｌ_２（ただし、Ｌ_１及びＬ_２は、互いに同一であってもよいし、異なっていてもよく、水素原子、アルキル基、アリール基、アルケニル基、アルコキシ基、アリールオキシ基、アルコキシカルボニル基、アリールオキシカルボニル基、アリールオキシスルホニル基、アリールカルボニルオキシ基、及び複素環基のいずれかを表し、これらは更に置換基により置換されていてもよい）のいずれかで表される前記＜８＞に記載の光記録媒体である。
＜１０＞ （Ｃ）成分が、下記構造式（７）で表されるジアリールアミン化合物である前記＜１＞から＜６＞のいずれかに記載の光記録媒体である。

ただし、前記構造式（７）中、Ｒ^２８及びＲ^２９は、互いに同一であってもよいし、異なっていてもよく、水素原子、又は置換基を有していてもよいアルキル基を表す。Ｒ^３０は、水素原子、アルキル基、及びアルキルアミノ基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｑ_３ ⁻は、アニオンを表す。
＜１１＞ 記録再生波長±１０ｎｍの波長領域の光に対する記録層単層の屈折率ｎが１．５≦ｎ≦３．０であり、かつ消衰係数ｋが０．０２≦ｋ≦０．３である前記＜１＞から＜１０＞のいずれかに記載の光記録媒体である。
＜１２＞ 記録再生波長が６００〜７２０ｎｍである前記＜１１＞に記載の光記録媒体である。
＜１３＞ 基板におけるトラックピッチが０．７〜０．８μｍであり、かつ案内溝幅が半値幅で０．１８〜０．４０μｍである前記＜１＞から＜１２＞のいずれかに記載の光記録媒体である。
＜１４＞ 反射層を有し、該反射層が金、銀、銅、アルミニウム、及びこれらの合金から選択されるいずれかを含有する前記＜１＞から＜１３＞のいずれかに記載の光記録媒体である。
＜１５＞ 前記＜１＞から＜１４＞のいずれかに記載の光記録媒体に対し、６００〜７２０ｎｍの記録波長で記録再生することを特徴とする光記録媒体の記録再生方法である。
＜１６＞ 光記録媒体に光源から光を照射して該光記録媒体に情報を記録する光記録装置において、前記光記録媒体が、前記＜１＞から＜１４＞のいずれかに記載の光記録媒体であることを特徴とする光記録装置である。 The present invention is based on the above findings of the present inventors, and means for solving the above problems are as follows. That is,
<1> A formazan metal chelate compound comprising a substrate and at least a recording layer on the substrate, wherein the recording layer has at least (A) a maximum absorption wavelength of an absorption spectrum of 500 nm or more and less than 650 nm; An optical recording medium comprising a squarylium compound having a maximum absorption wavelength of 500 nm or more and less than 650 nm and a compound (C) having a maximum absorption wavelength of absorption spectrum of 650 nm or more and 800 nm or less.
<2> The optical recording medium according to <1>, wherein the compound of component (C) is at least one selected from a formazan metal chelate compound, a pentamethine cyanine compound, a phthalocyanine compound, and a diarylamine compound.
<3> The mass ratio of the formazan metal chelate compound (A) to the squarylium compound (B) (component (A): component (B)) is 10:90 to 50:50, and (C) Any one of <1> to <2>, wherein the addition amount of the component compound is 0.5 to 20 parts by mass with respect to 100 parts by mass in total of the compound of the component (A) and the compound of the component (B). The optical recording medium described in 1.
<4> Formazan metal chelate compound of component (A) and formazan compound represented by at least one of structural formula (1) and structural formula (2) below, and metal and metal compound: The optical recording medium according to any one of <1> to <3>, wherein the formazan metal chelate compound is any one of the above.

However, in the structural formula (1), the ring X represents a heterocyclic ring formed by combining adjacent nitrogen and carbon atoms, and the heterocyclic ring may be further substituted with a substituent. It may be condensed with the ring. Z ₀ represents an atom constituting the ring X. A represents any of an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an alkenyl group, an alkoxycarbonyl group, and a heterocyclic group, and these may be further substituted with a substituent. B represents any of an alkyl group, an alkenyl group, and an aryl group, and these may be further substituted with a substituent.

However, in the structural formula (2), the ring Y and the ring Z may be the same as or different from each other, and a heterocyclic ring formed by combining an adjacent nitrogen atom and carbon atom together. And the heterocyclic ring may be further substituted with a substituent and may be condensed with another ring. Z ₁ and Z ₂ represent atoms constituting the ring Y and the ring Z, respectively. A ₁ and A ₂ may be the same or different from each other, and are any one of an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an alkenyl group, an alkoxycarbonyl group, and a heterocyclic group. These may be further substituted with a substituent. B ₁ and B ₂ may be the same as or different from each other, and represent an alkylene group, an alkenylene group, or an arylene group, and these may be further substituted with a substituent. W represents —CH ₂ — or —SO ₂ —. n is an integer of 0 or 1.
<5> One of the metal and the metal compound is at least one selected from vanadium, manganese, iron, cobalt, nickel, copper, zinc, palladium, an oxide of the metal, and a halide of the metal. The optical recording medium according to <4>.
<6> The optical recording medium according to any one of <1> to <5>, wherein the component (B) is a squarylium compound represented by any one of the following structural formula (3) and the following structural formula (4). is there.

However, in the structural formula (3), R ¹ and R ² may be the same as or different from each other, and are any of a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, and a heterocyclic group. These may be further substituted with a substituent, and R ¹ and R ² may be combined with the adjacent nitrogen atom to form a heterocyclic ring which may have a substituent. . R ³ represents a substituent represented by either the following structural formula (3-1) or the following structural formula (3-2).

However, in the structural formula (3-1), R ⁴ and R ⁵ may be the same as or different from each other, and may be a hydrogen atom or an alkyl group that may have a substituent. And these may be combined with an adjacent nitrogen atom to form an optionally substituted heterocycle. R ⁶ , R ⁷ , R ⁸ and R ⁹ may be the same as or different from each other, and represent any one of a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, and an alkoxy group, Further, it may be substituted with a substituent. R ⁴ and R ⁶ or R ⁵ and R ⁷ together with adjacent N—C—C may form a heterocyclic ring which may have a substituent.

However, Q < ₁ > represents either a carbon atom or a nitrogen atom in said structural formula (3-2). R ¹⁰ and R ¹¹ may be the same as or different from each other, and each represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and these are further substituted with a substituent. Also good. However, if _{Q 1} is a nitrogen ^{atom, R 11} is not present.
R ¹² represents any one of a hydrogen atom, an alkyl group, an aryl group, and an aralkyl group, and these may be further substituted with a substituent. R ¹³ and R ¹⁴ may be the same as or different from each other, and each represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and these are further substituted with a substituent. It may have a heterocyclic ring which may have a substituent together with two adjacent carbon atoms, an alicyclic hydrocarbon ring which may have a substituent, or a substituent. An aromatic ring may be formed.

In the Structural Formula (4), Q ₂ represents one of a carbon atom and a nitrogen atom. R ¹⁵ represents any one of a hydrogen atom, an alkyl group, an aryl group, and a heterocyclic group, and these may be further substituted with a substituent. R ¹⁶ represents any one of a hydrogen atom, a halogen atom, an amino group, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, and a heterocyclic group, and these may be further substituted with a substituent. R ¹⁷ and R ¹⁸ may be the same as or different from each other, and each represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and these are further substituted with a substituent. Alternatively, together with the adjacent carbon atom, a heterocyclic ring which may have a substituent or an alicyclic hydrocarbon ring which may have a substituent may be formed. However, when _{Q 2} is a nitrogen ^{atom, R 18} is not present.
R ¹⁹ represents any one of a hydrogen atom, an alkyl group, an aralkyl group, and an aryl group, and these may be further substituted with a substituent. R ²⁰ represents any one of a halogen atom, a nitro group, a cyano group, an alkyl group, an aralkyl group, an aryl group, and an alkoxy group, and these may be further substituted with a substituent. n represents an integer of 0 to 4. When n is 2 to 4, R ²⁰ may be the same as or different from each other, and two carbons adjacent to each other two R ²⁰ are adjacent to each other. An aromatic ring which may have a substituent may be formed together with the atom.
<7> The optical recording medium according to any one of <1> to <6>, wherein the component (C) is a pentamethine cyanine compound represented by the following structural formula (5).

However, in the structural formula (5), R ²¹ represents any one of a hydrogen atom, a halogen atom, an alkyl group, and an alkenyl group, and these may be further substituted with a substituent. R ²² and R ²³ may be the same as or different from each other, and each represents an alkyl group that may have a substituent. Q ⁻ represents an anion.
<8> The optical recording medium according to any one of <1> to <6>, wherein the component (C) is a phthalocyanine compound represented by the following structural formula (6).

However, in the structural formula (6), R ^{24 to} R ²⁷ may be the same as or different from each other, and are a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, an alkylsulfinyl group, an arylsulfinyl group. Represents any of a group, an alkylsulfonyl group, an arylsulfonyl group, an alkyloxysulfonyl group, an aryloxysulfonyl group, an alkoxy group, an arylcarbonyloxy group, and a heterocyclic group, which may be further substituted with a substituent. . q1~q4 represents an integer of 0 to 4, when q1~q4 is 2 to 4, each ^R 24 ^{to R 27} may be the same or may be different from one another. M ₁ represents any one of two hydrogen atoms, a metal atom, a metal compound, a metalloid atom, and a metalloid compound.
<9> M ₁ is V═O and L ₁ —Si—L ₂ (where L ₁ and L ₂ may be the same as or different from each other, and may be a hydrogen atom, an alkyl group, an aryl Group, an alkenyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an aryloxysulfonyl group, an arylcarbonyloxy group, and a heterocyclic group, which are further substituted with a substituent. The optical recording medium according to <8>, which is represented by any one of
<10> The optical recording medium according to any one of <1> to <6>, wherein the component (C) is a diarylamine compound represented by the following structural formula (7).

However, in the structural formula (7), R ²⁸ and R ²⁹ may be the same as or different from each other, and represent a hydrogen atom or an alkyl group that may have a substituent. R ³⁰ represents any one of a hydrogen atom, an alkyl group, and an alkylamino group, and these may be further substituted with a substituent. Q ₃ ⁻ represents an anion.
<11> The refractive index n of the recording layer single layer with respect to light in the recording / reproducing wavelength ± 10 nm wavelength range is 1.5 ≦ n ≦ 3.0, and the extinction coefficient k is 0.02 ≦ k ≦ 0.3. The optical recording medium according to any one of <1> to <10>, wherein
<12> The optical recording medium according to <11>, wherein the recording / reproducing wavelength is 600 to 720 nm.
<13> The light according to any one of <1> to <12>, wherein a track pitch in the substrate is 0.7 to 0.8 μm, and a guide groove width is 0.18 to 0.40 μm in half width. It is a recording medium.
<14> The optical recording according to any one of <1> to <13>, including a reflective layer, wherein the reflective layer contains any one selected from gold, silver, copper, aluminum, and alloys thereof. It is a medium.
<15> A recording / reproducing method for an optical recording medium, wherein the optical recording medium according to any one of <1> to <14> is recorded and reproduced at a recording wavelength of 600 to 720 nm.
<16> In an optical recording apparatus that records information on an optical recording medium by irradiating the optical recording medium with light from a light source, the optical recording medium is the optical recording according to any one of <1> to <14> An optical recording apparatus characterized by being a medium.

  The optical recording medium of the present invention comprises a substrate and a formazan metal chelate compound comprising at least a recording layer on the substrate, and the recording layer has (A) at least a maximum absorption wavelength of an absorption spectrum of 500 nm or more and less than 650 nm, (B) The squarylium compound whose absorption spectrum has a maximum absorption wavelength of 500 nm or more and less than 650 nm, and (C) a compound whose absorption spectrum has a maximum absorption wavelength of 650 nm or more and 800 nm or less. As a result, recording and reproduction can be performed with a laser beam having a wavelength range of 600 to 720 nm, and an optical recording medium excellent in light resistance, storage stability, and the like can be obtained.

  In the optical recording medium recording / reproducing method of the present invention, at least one of information recording and reproducing is performed by irradiating the optical recording medium of the present invention with a laser beam having an oscillation wavelength of 600 to 720 nm. As a result, there is little dependence on the wavelength shift of the semiconductor laser, and recording and reproduction can be performed stably with laser light in the wavelength region of 600 to 720 nm.

  The optical recording apparatus of the present invention uses the optical recording medium of the present invention as the optical recording medium in the optical recording apparatus that records information on the optical recording medium by irradiating the optical recording medium with light from a light source. In the optical recording apparatus of the present invention, there is little dependence on the wavelength shift of the semiconductor laser, and stable recording can be performed.

  According to the present invention, conventional problems can be solved, recording and reproduction can be performed with a laser beam having a wavelength range of 600 to 720 nm, and there is little dependency on the wavelength shift of the semiconductor laser, and light resistance, storage stability, etc. An excellent optical recording medium can be provided.

(Optical recording medium)
The optical recording medium of the present invention comprises a substrate and at least a recording layer on the substrate, and has a reflective layer, a protective layer, and other layers as required.
The recording layer includes at least (A) a formazan metal chelate compound having a maximum absorption wavelength of 500 nm or more and less than 650 nm, (B) a squarylium compound having a maximum absorption wavelength of 500 nm or more and less than 650 nm, and (C) A compound having a maximum absorption wavelength of an absorption spectrum of 650 nm or more and 800 nm or less, and the component (C) is at least selected from a formazan metal chelate compound, a pentamethine cyanine compound, a phthalocyanine compound, and a diarylamine compound One is preferred.

-Formazan metal chelate compound of component (A) and component (C)-
The formazan metal chelate compound comprises a formazan compound and one of a metal and a metal compound. The formazan compound is not particularly limited and can be appropriately selected from conventionally known compounds. For example, the following structural formula ( What is represented by at least any one of 1) and following Structural formula (2) is suitable.

ただし、前記構造式（１）中、環Ｘは、隣接する窒素原子と炭素原子が一緒になって形成される複素環を表し、該複素環は更に置換基により置換されていてもよく、他の環と縮合していてもよい。Ｚ_０は、環Ｘを構成する原子を表す。Ａは、アルキル基、アリール基、アルキルカルボニル基、アリールカルボニル基、アルケニル基、アルコキシカルボニル基、及び複素環基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｂは、アルキル基、アルケニル基、及びアリール基のいずれかを表し、これらは更に置換基で置換されていてもよい。

However, in the structural formula (1), ring X represents a heterocyclic ring formed by combining adjacent nitrogen and carbon atoms, and the heterocyclic ring may be further substituted with a substituent. It may be condensed with the ring. Z ₀ represents an atom constituting the ring X. A represents any one of an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an alkenyl group, an alkoxycarbonyl group, and a heterocyclic group, and these may be further substituted with a substituent. B represents any of an alkyl group, an alkenyl group, and an aryl group, and these may be further substituted with a substituent.

ただし、前記構造式（２）中、環Ｙ及び環Ｚは、互いに同一であってもよいし、異なっていてもよく、隣接する窒素原子と炭素原子が一緒になって形成される複素環を表し、該複素環は更に置換基により置換されていてもよく、他の環と縮合していてもよい。Ｚ_１及びＺ_２は、それぞれ環Ｙ及び環Ｚを構成する原子を表す。Ａ_１及びＡ_２は、互いに同一であってもよいし、異なっていてもよく、アルキル基、アリール基、アルキルカルボニル基、アリールカルボニル基、アルケニル基、アルコキシカルボニル基、及び複素環基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｂ_１及びＢ_２は、互いに同一であってもよいし、異なっていてもよく、Ｂ_１及びＢ_２は、互いに同一であってもよいし、異なっていてもよく、アルキレン基、アルケニレン基、又はアリーレン基を表し、これらは更に置換基で置換されていてもよい。Ｗは、−ＣＨ_２−、又は−ＳＯ_２−を表す。ｎは、０又は１の整数である。

However, in the structural formula (2), the ring Y and the ring Z may be the same as or different from each other, and a heterocyclic ring formed by combining an adjacent nitrogen atom and carbon atom together. And the heterocyclic ring may be further substituted with a substituent and may be condensed with another ring. Z ₁ and Z ₂ represent atoms constituting the ring Y and the ring Z, respectively. A ₁ and A ₂ may be the same or different from each other, and are any one of an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an alkenyl group, an alkoxycarbonyl group, and a heterocyclic group. These may be further substituted with a substituent. B ₁ and B ₂ may be the same as each other or different, B ₁ and B ₂ may be the same as each other or different, alkylene group, alkenylene group, Or an arylene group, which may be further substituted with a substituent. W represents —CH ₂ — or —SO ₂ —. n is an integer of 0 or 1.

In the structural formulas (1) and (2), the ring X, the ring Y, and the ring Z may be the same or different from each other, and adjacent nitrogen and carbon atoms are combined. Represents the heterocycle formed. The heterocycle is preferably a 5-membered ring or a 6-membered ring. Z ₀ , Z ₁ , and Z ₂ each represent an atom constituting ring X, ring Y, and ring Z, and examples thereof include a carbon atom, a nitrogen atom, a sulfur atom, an oxygen atom, and a selenium atom.

The heterocyclic ring may be condensed with another ring, and the other ring includes a heterocyclic ring in addition to a carbocyclic ring. In the case of a carbocyclic ring, the number of carbon atoms constituting the ring is preferably 6 to 20, and more preferably 6 to 10. Specific examples thereof include a benzene ring, a naphthalene ring, and a cyclohexane ring. On the other hand, in the case of a heterocyclic ring, the number of ring constituting atoms is preferably 5 to 20, and more preferably 5 to 14. Examples of the heterocyclic ring include pyrrolidine ring, thiazole ring, imidazole ring, oxazole ring, pyrazole ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, quinoline ring, indoline ring, carbazole ring and the like.
Examples of the ring X, ring Y and ring Z include a thiazole ring, an imidazole ring, a thiadiazole ring, an oxazole ring, a triazole ring, a pyrazole ring, an oxadiazole ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, and a triazine. A ring etc. are mentioned.
The substituents bonded to the ring X, ring Y and ring Z are each independently a halogen atom, nitro group, cyano group, hydroxyl group, carboxyl group, amino group, carbamoyl group, or optionally substituted alkyl. Group, aryl group which may have a substituent, heterocyclic group which may have a substituent, alkoxy group which may have a substituent, aryloxy which may have a substituent Group, alkylthio group optionally having substituent, arylthio group optionally having substituent, alkylamino group optionally having substituent, arylamino optionally having substituent Group, an alkoxycarbonyl group which may have a substituent, an aryloxycarbonyl group which may have a substituent, an alkylcarboxamide group which may have a substituent, and a substituent which may have a substituent An arylcarboxamide group, an alkylcarbamoyl group which may have a substituent, an arylcarbamoyl group which may have a substituent, an alkenyl group which may have a substituent, and a substituent. And an alkylsulfamoyl group that may be used.

In the structural formula (1) and the structural formula (2), A, A ₁ and A ₂ are each an alkyl group which may have a substituent, an aryl group which may have a substituent, An alkylcarbonyl group which may have a substituent, an arylcarbonyl group which may have a substituent, an alkenyl group which may have a substituent, a heterocyclic group which may have a substituent Or the alkoxycarbonyl group which may have a substituent is shown. In this case, the alkyl group and alkenyl group include linear, branched, or cyclic groups. The alkyl group preferably has 1 to 15 carbon atoms, more preferably 1 to 8 carbon atoms. The alkenyl group preferably has 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms.

  In the structural formula (1), B represents an alkyl group which may have a substituent, an alkenyl group which may have a substituent, or an aryl group which may have a substituent. In this case, the alkyl group and alkenyl group include linear, branched, or cyclic groups. Preferably the carbon number of the said alkyl group is 1-15, More preferably, it is 1-8, The carbon number of the said alkenyl group becomes like this. Preferably it is 2-8, More preferably, it is 2-6. The aryl group preferably has 6 to 18 carbon atoms, more preferably 6 to 14 carbon atoms.

In the structural formula (2), B ₁ and B ₂ may each have an alkylene group which may have a substituent, an alkenylene group which may have a substituent, or a substituent. Good arylene group. In this case, the alkylene group and alkenylene group include linear, branched, or cyclic groups. The alkylene group preferably has 1 to 15 carbon atoms, more preferably 1 to 8 carbon atoms. In the alkenylene group, the carbon number is preferably 2 to 8, more preferably 2 to 6. In the arylene group, the carbon number is preferably 6-18, more preferably 6-14.
In Structural Formula (2), W represents —CH ₂ — or —SO ₂ —, and n is an integer of 0 or 1.

  Examples of each alkyl group include those having 1 to 15 carbon atoms, such as a methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n- Linear alkyl groups such as heptyl group, n-octyl group, n-nonyl group, n-decyl group; isobutyl group, isoamyl group, 2-methylbutyl group, 2-methylpentyl group, 3-methylpentyl group, 4- Methylpentyl group, 2-ethylbutyl group, 2-methylhexyl group, 3-methylhexyl group, 4-methylhexyl group, 5-methylhexyl group, 2-ethylpentyl group, 3-ethylpentyl group, 2-methylheptyl group 3-methylheptyl group, 4-methylheptyl group, 5-methylheptyl group, 2-ethylhexyl group, 3-ethylhexyl group, isopropyl group, sec-butyl 1-ethylpropyl group, 1-methylbutyl group, 1,2-dimethylpropyl group, 1-methylheptyl group, 1-ethylbutyl group, 1,3-dimethylbutyl group, 1,2-dimethylbutyl group, 1-ethyl 2-methylpropyl group, 1-methylhexyl group, 1-ethylheptyl group, 1-propylbutyl group, 1-isopropyl-2-methylpropyl group, 1-ethyl-2-methylbutyl group, 1-propyl-2- Methylpropyl group, 1-ethylhexyl group, 1-propylpentyl group, 1-isopropylpentyl group, 1-isopropyl-2-methylbutyl group, 1-isopropyl-3-methylbutyl group, 1-methyloctyl group, 1-propylhexyl group 1-isobutyl-3-methylbutyl group, neopentyl group, tert-butyl group, tert-hexyl group, branched alkyl groups such as ert-amyl group and tert-octyl group; cyclohexyl group, 4-methylcyclohexyl group, 4-ethylcyclohexyl group, 4-tert-butylcyclohexyl group, 4- (2-ethylhexyl) cyclohexyl group, bornyl And cycloalkyl groups such as an isobornyl group and an adamantyl group. Among these, those having 1 to 8 carbon atoms are preferable.

  Each alkyl group may be substituted with a hydroxyl group, a halogen atom, a nitro group, a carboxyl group, a cyano group, or the like, or may have a specific substituent (for example, a halogen atom or a nitro group). And may be substituted with an aryl group or a heterocyclic group. Furthermore, it may be substituted with another hydrocarbon group such as the alkyl group through a heteroatom such as oxygen, sulfur or nitrogen. Here, examples of the aryl group, the heterocyclic group, and the halogen atom include those described later.

  Examples of the alkyl group substituted with another hydrocarbon group through oxygen include, for example, a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an ethoxyethyl group, a butoxyethyl group, an ethoxyethoxyethyl group, and a phenoxyethyl group. And an alkyl group substituted with an alkoxy group such as a methoxypropyl group or an ethoxypropyl group or an aryloxy group. These alkoxy groups and aryloxy groups may have a substituent.

  Examples of the alkyl group substituted with another hydrocarbon group via sulfur include, for example, an alkylthio group such as a methylthioethyl group, an ethylthioethyl group, an ethylthiopropyl group, and a phenylthioethyl group, an arylthio group, and the like. And alkyl groups. These alkylthio groups and arylthio groups may have a substituent.

  Examples of the alkyl group substituted with another hydrocarbon group via nitrogen include alkylamino groups such as dimethylaminoethyl group, diethylaminoethyl group, diethylaminopropyl group, phenylaminomethyl group, and arylamino groups. Examples include substituted alkyl groups. These alkylamino groups and arylamino groups may have a substituent.

  As the alkenyl group, those having 2 to 8 carbon atoms are preferable. For example, vinyl group, allyl group, 1-propenyl group, methacryl group, crotyl group, 1-butenyl group, 3-butenyl group, 2-pentenyl group. Group, 4-pentenyl group, 2-hexenyl group, 5-hexenyl group, 2-heptenyl group, 2-octenyl group and the like. Examples of the substituent for the alkenyl group include the same as those for the alkyl group.

Examples of the aryl group include a phenyl group, a naphthyl group, an anthranyl group, a fluorenyl group, a phenalenyl group, a phenanthranyl group, a triphenylenyl group, and a pyrenyl group.
Examples of the alkylene group and alkenylene group include those obtained by removing one hydrogen atom from the alkyl group and alkenyl group, respectively. Examples of the substituent for the alkylene group and alkenylene group are the same as those for the alkyl group.
Examples of the arylene group include those obtained by removing one hydrogen atom from the aryl group.
Examples of the aryl group and arylene group include an alkyl group, an alkenyl group, a hydroxyl group, a halogen atom, a nitro group, a carboxyl group, a cyano group, a trifluoromethyl group, an alkylamino group, an alkoxy group, an alicyclic heterocyclic group, An aryl group which may have a specific substituent (for example, optionally substituted by a halogen atom or a nitro group) or a specific substituent (for example, by a halogen atom or a nitro group) (It may be substituted.) It may be substituted with a heterocyclic group or the like.
Here, examples of the alkyl group, alkenyl group, and aryl group include those described above, and examples of the heterocyclic group and halogen atom include those described later.

Examples of the heterocyclic group include furyl group, thienyl group, pyrrolyl group, benzofuranyl group, isobenzofuranyl group, benzothienyl group, indolinyl group, isoindolinyl group, carbazolyl group, pyridyl group, piperidyl group, quinolyl group, isoquinolyl group. Group, oxazolyl group, isoxazolyl group, thiazolyl group, isothiazolyl group, imidazolyl group, pyrazolyl group, benzoimidazolyl group, pyrazyl group, pyrimidinyl group, pyridazinyl group, quinoxalinyl group and the like.
The heterocyclic group may have a hydroxyl group, an alkyl group, a halogen atom, a nitro group, a carboxyl group, a cyano group, or a specific substituent (for example, it may be substituted with a halogen atom or a nitro group). An aryl group, which may have a specific substituent (for example, may be substituted with a halogen atom or a nitro group), may be substituted with a heterocyclic group, and oxygen, sulfur, nitrogen, etc. It may be substituted with a hydrocarbon group such as the aforementioned alkyl group through a hetero atom. Here, examples of the alkyl group and aryl group include the same groups as described above, and examples of the heterocyclic group and halogen atom include those described later.

  Examples of the halogen atom include fluorine, chlorine, bromine, iodine and the like.

The alkoxy group which may have a substituent may be any group in which an alkyl group which may have a substituent is directly bonded to an oxygen atom. Examples of the alkyl group and the substituent include the specific examples described above.
The aryloxy group which may have a substituent may be any group as long as the aryl group which may have a direct substituent is bonded to an oxygen atom. Examples of the aryl group and the substituent include the specific examples described above.
As the alkylthio group which may have a substituent, any alkylthio group which may have a substituent directly to a sulfur atom may be used. Examples of the alkyl group and the substituent include the specific examples described above.
As the arylthio group which may have a substituent, any arylthio group which may have a substituent directly on the sulfur atom may be used. Examples of the aryl group and the substituent include the specific examples described above.

As the alkylamino group which may have a substituent, any alkylamino group which may have a substituent directly to the nitrogen atom may be used. Examples of the alkyl group and the substituent include the specific examples described above. In addition, alkyl groups may be bonded to each other to form a ring such as a piperidino group, a morpholino group, a pyrrolidinyl group, a piperazinyl group, an indolinyl group, or an isoindolinyl group containing an oxygen atom or other nitrogen atom. .
The arylamino group which may have a substituent may be any group as long as the aryl group which may have a substituent is directly bonded to the nitrogen atom. Examples of the aryl group and the substituent include the specific examples described above.
The alkylcarbonyl group which may have a substituent may be any as long as the alkyl group which may have a substituent is directly bonded to the carbon atom of the carbonyl group. Examples of the alkyl group and the substituent include the specific examples described above.
As the arylcarbonyl group which may have a substituent, any arylcarbonyl group which may have a substituent directly to the carbon atom of the carbonyl group may be used. Examples of the aryl group and the substituent include the specific examples described above.
The alkoxycarbonyl group which may have a substituent may be any group in which an alkyl group which may have a substituent is bonded directly to the oxygen atom of oxycarbonyl. Examples of the alkyl group and the substituent include the specific examples described above.
The aryloxycarbonyl group which may have a substituent may be any as long as the aryl group which may have a substituent is directly bonded to the oxygen atom of oxycarbonyl. Examples of the aryl group and the substituent include the specific examples described above.
The alkylcarboxamide group which may have a substituent may be any as long as an alkyl group which may have a substituent is directly bonded to a carbon atom of carboxamide. Examples of the alkyl group and the substituent include the specific examples described above.
The arylcarboxamide group which may have a substituent may be any as long as the aryl group which may have a substituent is directly bonded to the carbon atom of the carboxamide. Examples of the aryl group and the substituent include the specific examples described above.

The alkylcarbamoyl group which may have a substituent may be any as long as the alkyl group which may have a substituent is directly bonded to the nitrogen atom of the carbamoyl group. Examples of the alkyl group and the substituent include the specific examples described above. In addition, alkyl groups may be bonded to each other to form a ring such as a piperidino group, a morpholino group, a pyrrolidinyl group, a piperazinyl group, an indolinyl group, or an isoindolinyl group containing an oxygen atom or other nitrogen atom. .
The arylcarbamoyl group which may have a substituent may be any group as long as the aryl group which may have a substituent is bonded directly to the nitrogen atom of the carbamoyl group. Examples of the aryl group and the substituent include the specific examples described above.
The alkylsulfamoyl group which may have a substituent may be any as long as the alkyl group which may have a substituent is directly bonded to the nitrogen atom of the sulfamoyl group. Examples of the alkyl group and the substituent include the specific examples described above.

  The metal and metal compound in the formazan metal chelate compound may be any metal or metal compound capable of forming a chelate with the formazan compound, such as titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium. , Niobium, molybdenum, technetium, ruthenium, rhodium, palladium, oxides of these metals, halides of these metals, and the like. Among these, vanadium, manganese, iron, cobalt, nickel, copper, zinc, palladium, or oxides or halides thereof are particularly preferable. The optical recording medium of the present invention using the formazan metal chelate compound having these metals and the like has more excellent optical characteristics. Of the halides, chloride is preferably used.

  There is no restriction | limiting in particular as a formazan metal chelate compound represented by the said Structural formula (1) and the said Structural formula (2), What was synthesize | combined suitably may be used and a commercial item may be used. In the former case, it can be produced by a known method described in Japanese Patent No. 2791944, for example.

  Among the formazan metal chelate compounds represented by the structural formula (1) and the structural formula (2), specific examples in which the maximum absorption wavelength is 500 nm or more and less than 650 nm are shown in the following A-1 to A-16. Specific examples in which the maximum absorption wavelength is 650 nm or more and 800 nm or less are shown in C-1 to C-11 below. In the following table, Ph represents a phenyl group.

-(B) component squarylium compound-
What the said squarylium compound of the (B) component is represented by either the following structural formula (3) and the following structural formula (4) is preferable.

ただし、前記構造式（３）中、Ｒ^１及びＲ^２は、互いに同一であってもよいし、異なっていてもよく、水素原子、アルキル基、アラルキル基、アリール基、及び複素環基のいずれかを表し、これらは更に置換基で置換されていてもよく、Ｒ^１及びＲ^２は隣接する窒素原子と一緒になって置換基を有していてもよい複素環を形成していてもよい。Ｒ^３は、下記構造式（３−１）及び下記構造式（３−２）のいずれかで表される置換基を表す。

However, in the structural formula (3), R ¹ and R ² may be the same as or different from each other, and are any of a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, and a heterocyclic group. These may be further substituted with a substituent, and R ¹ and R ² may be combined with the adjacent nitrogen atom to form a heterocyclic ring which may have a substituent. . R ³ represents a substituent represented by either the following structural formula (3-1) or the following structural formula (3-2).

ただし、前記構造式（３−１）中、Ｒ^４及びＲ^５は、互いに同一であってもよいし、異なっていてもよく、水素原子、又は置換基を有していてもよいアルキル基を表し、これらは隣接する窒素原子と一緒になって置換基を有していてもよい複素環を形成してもよい。Ｒ^６、Ｒ^７、Ｒ^８及びＲ^９は、互いに同一であってもよいし、異なっていてもよく、水素原子、ハロゲン原子、水酸基、アルキル基、及びアルコキシ基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｒ^４及びＲ^６又はＲ^５及びＲ^７は、隣接するＮ−Ｃ−Ｃと一緒になって置換基を有していてもよい複素環を形成してもよい。

However, in the structural formula (3-1), R ⁴ and R ⁵ may be the same as or different from each other, and may be a hydrogen atom or an alkyl group that may have a substituent. And these may be combined with an adjacent nitrogen atom to form an optionally substituted heterocycle. R ⁶ , R ⁷ , R ⁸ and R ⁹ may be the same as or different from each other, and represent any one of a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, and an alkoxy group, Further, it may be substituted with a substituent. R ⁴ and R ⁶ or R ⁵ and R ⁷ together with adjacent N—C—C may form a heterocyclic ring which may have a substituent.

ただし、前記構造式（３−２）中、Ｑ_１は、炭素原子及び窒素原子のいずれかを表す。Ｒ^１０及びＲ^１１は、互いに同一であってもよいし、異なっていてもよく、水素原子、アルキル基、アリール基、及びアラルキル基のいずれかを表し、これらは更に置換基により置換されていてもよい。ただし、Ｑ_１が窒素原子である場合、Ｒ^１１は存在しない。

However, Q < ₁ > represents either a carbon atom or a nitrogen atom in said structural formula (3-2). R ¹⁰ and R ¹¹ may be the same as or different from each other, and each represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and these are further substituted with a substituent. Also good. However, if _{Q 1} is a nitrogen ^{atom, R 11} is not present.

R ¹² represents any one of a hydrogen atom, an alkyl group, an aryl group, and an aralkyl group, and these may be further substituted with a substituent. R ¹³ and R ¹⁴ may be the same as or different from each other, and each represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and these are further substituted with a substituent. It may have a heterocyclic ring which may have a substituent together with two adjacent carbon atoms, an alicyclic hydrocarbon ring which may have a substituent, or a substituent. An aromatic ring may be formed.

ただし、前記構造式（４）中、Ｑ_２は、炭素原子及び窒素原子のいずれかを表す。Ｒ^１５は、水素原子、アルキル基、アリール基、及び複素環基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｒ^１６は、水素原子、ハロゲン原子、アミノ基、アルキル基、アルコキシ基、アラルキル基、アリール基、及び複素環基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｒ^１７及びＲ^１８は、互いに同一であってもよいし、異なっていてもよく、水素原子、アルキル基、アリール基、及びアラルキル基のいずれかを表し、これらは更に置換基により置換されていてもよく、隣接する炭素原子と一緒になって置換基を有していてもよい複素環又は置換基を有していてもよい脂環式炭化水素環を形成してもよい。ただし、Ｑ_２が窒素原子の場合、Ｒ^１８は存在しない。

In the Structural Formula (4), Q ₂ represents one of a carbon atom and a nitrogen atom. R ¹⁵ represents any one of a hydrogen atom, an alkyl group, an aryl group, and a heterocyclic group, and these may be further substituted with a substituent. R ¹⁶ represents any one of a hydrogen atom, a halogen atom, an amino group, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, and a heterocyclic group, and these may be further substituted with a substituent. R ¹⁷ and R ¹⁸ may be the same as or different from each other, and each represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and these are further substituted with a substituent. Alternatively, it may be combined with an adjacent carbon atom to form an optionally substituted heterocyclic ring or an optionally substituted alicyclic hydrocarbon ring. However, when _{Q 2} is a nitrogen ^{atom, R 18} is not present.

R ¹⁹ represents a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group, and these may be further substituted with a substituent. R ²⁰ represents any one of a halogen atom, a nitro group, a cyano group, an alkyl group, an aralkyl group, an aryl group, and an alkoxy group, and these may be further substituted with a substituent. n represents an integer of 0 to 4. When n is 2 to 4, R ²⁰ may be the same as or different from each other, and two carbons adjacent to each other two R ²⁰ are adjacent to each other. An aromatic ring which may have a substituent may be formed together with the atom.

  Examples of the alkyl moiety in the alkyl group and the alkoxy group include linear or branched alkyl groups having 1 to 6 carbon atoms or cyclic alkyl groups having 3 to 8 carbon atoms, such as a methyl group, an ethyl group, Propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, isopentyl group, 1-methylbutyl group, 2-methylbutyl group, tert-pentyl group, hexyl group, cyclopropyl group, A cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, etc. are mentioned.

Examples of the aryl moiety of the aryl group and aralkyl group include a phenyl group, a naphthyl group, and an anthryl group. Examples of the alkylene part of the aralkyl group include those obtained by removing one hydrogen atom from the alkyl group.
Examples of the halogen atom include fluorine, chlorine, bromine, iodine and the like.

Heterocycle in the heterocyclic group, a heterocycle formed by R ¹³ and R ¹⁴ together with two adjacent carbon atoms, and a heterocycle formed by R ¹⁷ and R ¹⁸ together with adjacent carbon atoms Examples include aromatic heterocycles and alicyclic heterocycles.

  Examples of the aromatic heterocycle include a 5- or 6-membered monocyclic aromatic heterocycle containing at least one atom selected from a nitrogen atom, an oxygen atom and a sulfur atom, and a condensed 3- to 8-membered ring. And a condensed aromatic heterocycle containing at least one atom selected from a nitrogen atom, an oxygen atom, and a sulfur atom. Specific examples thereof include a pyridine ring, a pyrazine ring, and a pyrimidine. Ring, pyridazine ring, quinoline ring, isoquinoline ring, phthalazine ring, quinazoline ring, quinoxaline ring, naphthyridine ring, cinnoline ring, pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, thiophene ring, furan ring, thiazole ring, Oxazole ring, indole ring, isoindole ring, indazole ring, benzimidazole ring, benzotriazole ring, benzo Azole ring, benzoxazole ring, purine ring, carbazole ring.

  Examples of the alicyclic heterocycle include a 5-membered or 6-membered monocyclic alicyclic heterocycle and a 3- to 8-membered ring containing at least one atom selected from a nitrogen atom, an oxygen atom, and a sulfur atom. And a condensed alicyclic heterocycle containing at least one atom selected from a nitrogen atom, an oxygen atom and a sulfur atom, and more specifically a pyrrolidine ring, a piperidine Ring, piperazine ring, morpholine ring, thiomorpholine ring, homopiperidine ring, homopiperazine ring, tetrahydropyridine ring, tetrahydroquinoline ring, tetrahydroisoquinoline ring, tetrahydrofuran ring, tetrahydropyran ring, dihydrobenzofuran ring, tetrahydrocarbazole ring, etc. .

Heterocycle formed by R ¹ and R ² , or R ⁴ and R ⁵ together with adjacent nitrogen atom, and R ⁴ and R ⁶ , or R ⁵ and R ⁷ together with adjacent N—C—C Examples of the heterocyclic ring formed as above include an aromatic heterocyclic ring containing a nitrogen atom and an alicyclic heterocyclic ring containing a nitrogen atom.
Examples of the aromatic heterocycle containing a nitrogen atom include a 5-membered or 6-membered monocyclic aromatic heterocycle containing at least one nitrogen atom, and a bicyclic or tricyclic condensed 3- to 8-membered ring. Examples thereof include condensed aromatic heterocycles containing at least one nitrogen atom, and more specifically, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, quinoline ring, isoquinoline ring, phthalazine ring, quinazoline ring, quinoxaline ring. , Naphthyridine ring, cinnoline ring, pyrrole ring, pyrazole ring, imidazole ring, triazole ring, tetrazole ring, thiazole ring, oxazole ring, indole ring, isoindole ring, indazole ring, benzimidazole ring, benzotriazole ring, benzothiazole ring, Examples thereof include a benzoxazole ring, a purine ring, and a carbazole ring.

  Examples of the alicyclic heterocycle containing a nitrogen atom include, for example, a 5-membered or 6-membered monocyclic alicyclic heterocycle containing at least one nitrogen atom, and a nitrogen atom condensed with a 3- to 8-membered ring. Examples include a condensed alicyclic heterocyclic ring containing one, and more specifically, pyrrolidine ring, piperidine ring, piperazine ring, morpholine ring, thiomorpholine ring, homopiperidine ring, homopiperazine ring, tetrahydropyridine ring, tetrahydro A quinoline ring, a tetrahydroisoquinoline ring, a tetrahydrocarbazole ring, etc. are mentioned.

An alicyclic hydrocarbon ring formed by R ¹³ and R ¹⁴ together with two adjacent carbon atoms, and an alicyclic hydrocarbon ring formed by R ¹⁷ and R ¹⁸ together with an adjacent carbon atom Examples thereof include those having 3 to 8 carbon atoms, and may be saturated or unsaturated. For example, a cyclopropane ring, a cyclobutane ring, a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring, Examples include a cyclopentene ring, 1,3-cyclopentadiene ring, cyclohexene ring, cyclohexadiene ring and the like.
An aromatic ring formed by R ¹³ and R ¹⁴ together with two adjacent carbon atoms, and an aromatic ring formed by two adjacent R ²⁰ atoms together with two adjacent carbon atoms include And those having 6 to 14 carbon atoms, and examples thereof include a benzene ring, a naphthalene ring, and an anthracene ring.

The aryl group, aralkyl group, heterocyclic group, R ¹ and R ² , or the heterocyclic ring formed by R ⁴ and R ⁵ together with the adjacent nitrogen atom, R ⁴ and R ⁶ , or R ⁵ and R ⁷ A heterocycle formed by combining N—C—C with adjacent N, a heterocycle formed by combining two adjacent carbon atoms with R ¹³ and R ^14, and a carbon atom with adjacent R ¹⁷ and R ¹⁸ A heterocycle formed together with R ¹³ and R ¹⁴ or an alicyclic hydrocarbon ring formed together with two adjacent carbon atoms R ¹⁷ and R ¹⁸ , adjacent to R ¹³ and R ¹⁴ The aromatic ring formed together with two carbon atoms or the substituents of the aromatic ring formed together with two adjacent carbon atoms formed by two adjacent R ²⁰ may be the same or different. 1 to the number that can be replaced, preferably Or 1 to 5 substituents such as a hydroxyl group, a carboxyl group, a nitro group, an alkoxy group, an alkyl group, an aralkyl group, a cyano group, a halogen atom, -N = N-Ar (Ar is a hydroxyl group, a carboxyl group, A nitro group, an alkoxy group, an alkyl group which may be substituted with a halogen atom, or an aryl group which may be substituted with a cyano group or a substituent such as a halogen atom.), —CH═CH—Ar ( Ar is as defined above.) And the like. Examples of the alkyl group, alkoxy group, aralkyl group, aryl group and halogen atom are the same as those described above.

The substituent for the alkyl group or alkoxy group may be the same or different and may be the same or different, preferably 1 to 3 substituents such as a hydroxyl group, a carboxyl group, a nitro group, an alkoxy group, an aryl group. And halogen atoms. Examples of the alkoxy group, aryl group and halogen atom are the same as those described above.
Examples of the substituent of the amino group include one or two substituents which may be the same or different, such as an alkyl group and an aryl group. Examples of the alkyl group and aryl group are the same as those described above.

  The squarylium compound represented by the structural formula (3) can be produced according to a known method (for example, WO 01/44375 pamphlet). The squarylium compound represented by the structural formula (4) can be produced according to a known method (for example, International Publication No. 01/44233 pamphlet).

  Specific examples of the squarylium compound represented by the structural formula (3) and the structural formula (4) are shown below. In the following tables, nPr represents an n-propyl group, iPr represents an isopropyl group, and Ph represents a phenyl group.

  In the optical recording medium of the present invention, (C) the maximum absorption wavelength is 650 nm or more and 800 nm or less with respect to the mixed dye material of (A) formazan metal chelate compound having a maximum absorption wavelength of 500 nm or more and less than 650 nm and (B) squarylium compound By adding the compound, it is possible to reduce the dependence on the wavelength shift of the semiconductor laser. Examples of the compound (C) include at least one compound selected from the formazan metal chelate compounds, pentamethine cyanine compounds, phthalocyanine compounds, and diarylamine compounds described above.

-Pentamethine cyanine compound of component (C)-
There is no restriction | limiting in particular as a pentamethine cyanine compound of said (C) component, It can select suitably from a conventionally well-known thing, For example, what is represented by following Structural formula (5) is suitable.

ただし、前記構造式（５）中、Ｒ^２１は、水素原子、ハロゲン原子、アルキル基、及びアルケニル基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｒ^２２及びＲ^２３は、互いに同一であってもよいし、異なっていてもよく、置換基を有していてもよいアルキル基を表す。Ｑ⁻は、アニオンを表す。

However, in the structural formula (5), R ²¹ represents any one of a hydrogen atom, a halogen atom, an alkyl group, and an alkenyl group, and these may be further substituted with a substituent. R ²² and R ²³ may be the same as or different from each other, and each represents an alkyl group that may have a substituent. Q ⁻ represents an anion.

Examples of the halogen atom, alkyl group, and alkenyl group are the same as those in the structural formula (1) and the structural formula (2).
In the alkyl group or alkenyl group which may have the substituent, the carbon number thereof is 1 to 12, preferably 1 to 6. The alkyl group or alkenyl group can be a chain or a cyclic group. The alkyl group and alkenyl group may contain a hetero atom such as an oxygen atom, a nitrogen atom, or a sulfur atom in the main chain. Examples of the substituent include the same as those in the structural formula (1) and the structural formula (2).
Q ⁻ represents an anion, and examples of the anion include I ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ , TsO (p-toluenesulfonyloxy) ^{− and the} like.

  There is no restriction | limiting in particular as a pentamethine cyanine compound represented by the said Structural formula (5), What was synthesize | combined suitably may be used and a commercial item may be used. In the former case, for example, it can be produced by a known method described in JP-A No. 09-208560.

  Specific examples of the pentamethine cyanine compound represented by the structural formula (5) are shown below. In the following tables, nPr represents an n-propyl group, nBu represents an n-butyl group, iBu represents an isobutyl group, and nHex represents an n-hexyl group.

-(C) Component phthalocyanine compound-
There is no restriction | limiting in particular as a phthalocyanine compound of the said (C) component, It can select suitably from conventionally well-known things, For example, what is represented by following Structural formula (6) is preferable.

ただし、前記構造式（６）中、Ｒ^２４〜Ｒ^２７は、互いに同一であってもよいし、異なっていてもよく、水素原子、アルキル基、アリール基、アルケニル基、アルキルスルフィニル基、アリールスルフィニル基、アルキルスルホニル基、アリールスルホニル基、アルキルオキシスルホニル基、アリールオキシスルホニル基、アルコキシ基、アリールカルボニルオキシ基、及び複素環基のいずれかを表し、これらは更に置換基により置換されていてもよい。ｑ１〜ｑ４は、０〜４の整数を表し、ｑ１〜ｑ４が２〜４の場合、各Ｒ^２４〜Ｒ^２７は互いに同一であってもよいし、異なっていてもよい。Ｍ_１は、２個の水素原子、金属、金属化合物、半金属、及び半金属化合物のいずれかを表す。

However, in the structural formula (6), R ^{24 to} R ²⁷ may be the same as or different from each other, and are a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, an alkylsulfinyl group, an arylsulfinyl group. Represents any of a group, an alkylsulfonyl group, an arylsulfonyl group, an alkyloxysulfonyl group, an aryloxysulfonyl group, an alkoxy group, an arylcarbonyloxy group, and a heterocyclic group, which may be further substituted with a substituent. . q1~q4 represents an integer of 0 to 4, when q1~q4 is 2 to 4, each ^R 24 ^{to R 27} may be the same or may be different from one another. M ₁ represents any one of two hydrogen atoms, a metal, a metal compound, a metalloid, and a metalloid compound.

In the alkylsulfinyl group, the alkyl group preferably has 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms. The alkyl group includes chain and cyclic groups and unsaturated groups.
In the arylsulfinyl group, the aryl group preferably has 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms.
In the alkylsulfonyl group, the alkyl group preferably has 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms. The alkyl group includes chain and cyclic groups and unsaturated groups.
In the arylsulfonyl group, the aryl group preferably has 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms.
In the alkyloxysulfonyl group, the alkyl group preferably has 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms. The alkyl group includes chain and cyclic groups and unsaturated groups.
In the aryloxysulfonyl group, the aryl group preferably has 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms.
In the alkoxy group, the alkyl group preferably has 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms. The alkyl group includes chain and cyclic groups and unsaturated groups.
In the arylcarbonyloxy group, the aryl group preferably has 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms.

Here, examples of the alkyl group, the aryl group, the alkenyl group, and the heterocyclic group include those similar to those in the structural formula (1) and the structural formula (2).
Each group may have a substituent. Specific examples of such a substituent include ring X, ring Y, and ring Z in the structural formula (1) and the structural formula (2). The various substituents shown with respect to can be shown.

Examples of M ₁ include two hydrogen atoms, metal atoms, metal compounds, metalloid atoms, and metalloid compounds. For example, two hydrogen atoms, a divalent unsubstituted metal atom, and coordination A divalent metal atom having a child; a trivalent metal atom having a substituent as a metal compound, or a tetravalent metal atom having a substituent; a trivalent metal atom having a substituent as a metalloid compound; Examples thereof include a tetravalent semimetal atom having a substituent; an oxymetal atom and the like.

Examples of the divalent unsubstituted metal atom include Cu, Zn, Fe, Co, Ni, Ru, Rh, Pd, Pt, Mn, Sn, Mg, Pb, Hg, Cd, Ba, Ti, Be, and Ca. Etc.
Examples of the divalent metal atom having the ligand include Cu (NH ₃ ) ₂ , Fe (NH ₃ ) ₂ , Fe (pyridine) ₂ , Fe (γ-picoline) ₂ , and Fe (tosylmethyl isocyanide). ₂ , Fe (benzyl isocyanide) _{2 and the} like.
Examples of the trivalent metal atom having the substituent include Al-F, Al-Cl, Al-Br, Al-I, Ga-F, Ga-Cl, Ga-Br, Ga-I, and In-F. , In-Cl, In-Br , In-I, Ti-F, Ti-Cl, Ti-Br, Ti-I, Al-C 6 H 5, Al-C 6 H 4 (CH 3), In-C _{6 H 5, In-C 6} H 4 (CH 3), Mn (OH), Mn (OCH 3), Mn (OC 6 H 5), Mn [OSi _{(CH 3)} 3], Fe-F, Fe- Cl, Fe—Br, Fe—I, Ru—F, Ru—Cl, Ru—Br, Ru—I and the like can be mentioned.

Examples of the tetravalent metal atom having the substituent include CrCl ₂ , SnF ₂ , SnCl ₂ , SnBr ₂ , SnI ₂ , ZnF ₂ , ZnCl ₂ , ZnBr ₂ , ZnI ₂ , GeF ₂ , GeCl ₂ , GeBr _2. , GeI ₂ , TiF ₂ , TiCl ₂ , TiBr ₂ , TiI ₂ , Sn (OH) ₂ , Ge (OH) ₂ , Zr (OH) ₂ , Mn (OH) ₂ , TiL ₂ , CrL ₂ , SiL ₂ , SnL ₂ , GeL ₂ , Ti (OL) ₂ , Cr (OL) ₂ , Sn (OL) ₂ , Ge (OL) ₂ , Ti (SL) ₂ , Cr (SL) ₂ , Sn (SL) ₂ , Ge (SL ) ₂ [where, L is an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an aryloxy sulfonyl group, and Ariruka It represents either Boniruokishi group, which may further be substituted by a substituent. ] Etc. are mentioned.

Examples of the trivalent metalloid atom having a substituent include BF, B-Cl, B-Br, BI, BL, B (OH), B (OL), B [OSi ( CH ₃ ) ₃ ] [wherein L represents the same meaning as L described above] and the like.

Examples of the tetravalent metalloid atom having the substituent include SiF ₂ , SiCl ₂ , SiBr ₂ , SiI ₂ , Si (OH) ₂ , SiL ₂ , Si (OL) ₂ , and Si (SL) _2. , L represents the same meaning as L described above] and the like.
Examples of the oxymetal atom include VO, MnO, TiO and the like.

Among these, _{M 1} is, V = O and _L 1 _{-Si-L 2} (but, _{L 1} and _{L 2} may be the same as each other or different, a hydrogen atom, an alkyl group, An aryl group, an alkenyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an aryloxysulfonyl group, an arylcarbonyloxy group, or a heterocyclic group, which is further substituted with a substituent. It is preferable that any one of them may be represented.
Here, the alkyl group, aryl group, alkenyl group, heterocyclic group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, aryloxysulfonyl group, and arylcarbonyloxy group include the structural formula ( Examples thereof are the same as those in 1) and the structural formula (2).

  There is no restriction | limiting in particular as a phthalocyanine compound represented by the said Structural formula (6), What was synthesize | combined suitably may be used and a commercial item may be used. In the former case, it can be produced by a known method described in JP-A-7-286108, for example.

Specific examples of the phthalocyanine compound represented by the structural formula (6) are shown below.

  The phthalocyanine compound typically shows only one isomer. For example, in the case of a compound having a substituent at the α-position, there are four types of isomers represented by the following structural formula. Has become a mixture.

-Diarylamine compound of component (C)-
There is no restriction | limiting in particular as a diarylamine compound of said (C) component, According to the objective, it can select suitably from what is conventionally well-known, For example, what is represented by following Structural formula (7) is preferable.

ただし、前記構造式（７）中、Ｒ^２８及びＲ^２９は、互いに同一であってもよいし、異なっていてもよく、水素原子、又は置換基を有していてもよいアルキル基を表す。Ｒ^３０は、水素原子、アルキル基、及びアルキルアミノ基のいずれかを表し、これらは更に置換基により置換されていてもよい。Ｑ_３ ⁻は、アニオンを表す。

However, in the structural formula (7), R ²⁸ and R ²⁹ may be the same as or different from each other, and represent a hydrogen atom or an alkyl group that may have a substituent. R ³⁰ represents any one of a hydrogen atom, an alkyl group, and an alkylamino group, and these may be further substituted with a substituent. Q ₃ ⁻ represents an anion.

The alkyl group has 1 to 15 carbon atoms, preferably 1 to 8 carbon atoms.
In the alkylamino group, the alkyl group preferably has 1 to 15 carbon atoms, more preferably 1 to 8 carbon atoms. The alkyl group includes chain and cyclic groups and unsaturated groups.
Specific examples of the substituent for the alkyl group and alkylamino group include the same ones as those shown for the compound represented by the structural formula (1).
Q ₃ ⁻ represents an anion, and examples of the anion include I ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ , TsO (p-toluenesulfonyloxy) ^{− and the} like.

  There is no restriction | limiting in particular as a diarylamine compound represented by said Structural formula (7), What was synthesize | combined suitably may be used and a commercial item may be used. In the former case, it can be produced by a known method described in, for example, “Horiguchi Hiroshi: Review Synthetic Dye, p360, Sankyo Publishing (1969)”.

Specific examples of the diarylamine compound represented by the structural formula (7) are shown below.

  In the recording layer, the mass ratio of the formazan metal chelate compound (A) to the squarylium compound (B) (component (A): component (B)) is preferably 10:90 to 50:50. 15: 85-45: 55 is more preferable.

The amount of the component (C) compound added is preferably 0.5 to 20 parts by mass, and 1 to 5 parts by mass with respect to 100 parts by mass in total of the compound (A) and the compound (B). More preferred. When the addition amount is less than 0.5 parts by mass, a predetermined effect may not be obtained, and when it exceeds 20 parts by mass, other characteristics (particularly reflectance) may not be satisfied.
A mixture of (A) a formazan metal chelate compound having a maximum absorption wavelength of 500 nm or more and less than 650 nm and (B) a squarylium compound having a maximum absorption wavelength of 500 nm or more and less than 650 nm. By adding a compound having a maximum absorption wavelength of 650 nm or more and 800 nm or less (formazan metal chelate compound, pentamethine cyanine compound, phthalocyanine compound, diarylamine compound, etc.) within the above range, the basic characteristics of write-once DVD media are maintained. However, it is possible to reduce the so-called wavelength dependency of the recording sensitivity with respect to the wavelength variation of the recording laser.

The recording layer of the optical recording medium of the present invention is preferably excellent in optical characteristics, light resistance and the like.
As optical characteristics, it is preferable that the recording / reproducing wavelength has a large absorption band on the short wavelength side with respect to 600 to 720 nm, and the recording / reproducing wavelength is in the vicinity of the long wavelength end of the absorption band. This means that it has a large refractive index and extinction coefficient at a recording / reproducing wavelength of 600 to 720 nm.

Specifically, the refractive index n of the recording layer single layer with respect to light in the wavelength range of the recording / reproducing wavelength ± 10 nm is 1.5 or more and 3.0 or less, and the extinction coefficient k is 0.02 or more and 0.3 or less. It is preferable to be in the range. When n is 1.5 or more, a sufficient optical change is obtained, which is preferable because the recording modulation degree is high. When n is 3.0 or less, the wavelength dependency is not higher. Even in the recording / reproducing wavelength region, it is preferable that a reproduction error hardly occurs. Further, when k is 0.02 or more, it is preferable because the recording sensitivity is improved, and when k is 0.3 or less, it is preferable to obtain a reflectance of 50% or more. Further, since the refractive index n can be increased as the extinction coefficient increases, the log ε (ε is the molar extinction coefficient) is preferably 5 or more.
Further, as light resistance, it is preferable to have reproduction stability of 1,000,000 times or more and fastness that does not fade when left indoors.

Next, the configuration of the optical recording medium of the present invention will be described with reference to the drawings.
FIG. 2 is a schematic sectional view showing an example of a layer structure applicable to the write-once type optical recording medium of the present invention, which is an example of a write-once type optical disc. FIG. 2A shows a write-once optical disc composed of substrate 1 / recording layer 2. FIG. 2B shows a write-once optical disc composed of substrate 1 / undercoat layer 3 / recording layer 2. FIG. 2C shows a write-once optical disc composed of a substrate 1 / undercoat layer 3 / recording layer 2 / protective layer 4. FIG. 2D shows a write-once optical disc comprising a hard coat layer 5 / substrate 1 / undercoat layer 3 / recording layer 2 / protective layer 4.

FIG. 3 is a schematic cross-sectional view showing an example of the layer structure of a write-once optical recording medium (CD-R type) that can be applied to the optical recording medium of the present invention. This is an example of a write-once optical disk. FIG. 3A shows a CD-R composed of substrate 1 / recording layer 2 / reflection layer 6 / protective layer 4. FIG. 3B shows a CD-R composed of substrate 1 / undercoat layer 3 / recording layer 2 / reflection layer 6 / protective layer 4. FIG. FIG. 3C shows a CD-R composed of hard coat layer 5 / substrate 1 / undercoat layer 3 / recording layer 2 / reflective layer 6 / protective layer 4.
In addition, it is good also as what is called an air sandwich which stuck two sheets of FIG. 2 or FIG.

  FIG. 4 is a schematic cross-sectional view showing an example of the layer structure of a write-once optical recording medium (DVD + R or DVD-R) that can be applied to the optical recording medium of the present invention. FIG. 4A shows a DVD + R or DVD-R composed of substrate 1 / recording layer 2 / reflective layer 6 / protective layer 4 / adhesive layer 8 / protective substrate 7. FIG. FIG. 4B shows a DVD + R or DVD-R composed of hard coat layer 5 / substrate 1 / undercoat layer 3 / recording layer 2 / reflection layer 6 / protective layer 4 / adhesive layer 8 / protective substrate 7.

  The configuration of the optical recording medium when the optical recording medium of the present invention is applied as a write-once DVD medium includes a first substrate and a second substrate (hereinafter sometimes referred to as a first substrate and a second substrate). A basic structure is a structure in which a recording layer is laminated with an adhesive. The recording layer is preferably a laminate of a recording layer and a reflective layer in order to increase the reflectance. The recording layer and the substrate may be formed through an undercoat layer or a protective layer, or may be laminated to improve the function. The structure most commonly used is the structure of the first substrate / recording layer (organic dye layer) / reflective layer / protective layer / adhesive layer / second substrate.

-Board-
The substrate must be transparent to the laser beam used only when recording / reproduction is performed from the substrate side, and the substrate does not have to be transparent when recording / reproduction is performed from the recording layer side. Therefore, in the present invention, when two substrates are used in a sandwich shape, for example, if only one substrate (second substrate) is transparent, it does not matter whether the other substrate (first substrate) is transparent or opaque. Absent.

There is no restriction | limiting in particular as said board | substrate material, According to the objective, it can select suitably, For example, plastics, such as a polyester resin, an acrylic resin, a polyamide resin, a polycarbonate resin, a polyolefin resin, a phenol resin, an epoxy resin, a polyimide resin Glass, ceramics, metal and the like can be used.
If only one layer is used, the pre-format such as tracking guide grooves and guide pits, and address signals, etc. on the surface of the substrate when two substrates are used in a sandwich shape. Is preferably formed.

The substrate is disk-shaped and usually has guide grooves with a depth of 1000 to 2500 mm (100 to 250 nm). When the groove depth is 1000 mm (100 nm) or more, sufficient tracking signals and good recording / reproducing characteristics can be easily obtained, and when the groove depth is 2500 mm (250 nm) or less, transfer properties with excellent uniformity can be obtained over the entire surface. It is preferable because it is easy. Further, the groove width is preferably 0.18 to 0.40 μm in half width. The half width is preferably 0.18 μm or more because sufficient tracking error signal intensity can be easily obtained. On the other hand, it is preferable that the thickness is 0.40 μm or less because the recording portion hardly spreads horizontally when recording.
The track pitch is usually preferably from 0.7 to 1.0 μm, and preferably from 0.7 to 0.8 μm for high capacity use.

-Recording layer-
The recording layer has some optical change caused by laser light irradiation, and information can be recorded by the change. In the recording layer, the (A) component, (B) component, and ( It is necessary for the compound of component C) to be contained, and when forming the recording layer, the compounds of component (A), component (B), and component (C) of the present invention are used alone or in combination of two or more. Can be used in combination. The recording layer may be mixed or laminated with other organic dyes and metals or metal compounds for the purpose of improving optical characteristics, recording sensitivity, signal characteristics, and the like.
Examples of the other organic dyes include polymethine dyes, naphthalocyanine dyes, croconium dyes, pyrylium dyes, naphthoquinone dyes, anthraquinone (indanthrene) dyes, xanthene dyes, triphenylmethane dyes, azulene Dyes, tetrahydrocholine dyes, phenanthrene dyes, triphenothiazine dyes, metal chelate compounds, and the like. These may be used alone or in combination of two or more.
Further, a metal or a metal compound can be added to the recording layer. As the metal or metal compound, for example, In, Te, Bi, Se, Sb, Ge, Sn, Al, Be, TeO ₂ , SnO, As, Cd and the like can be used in the form of dispersion mixing or lamination.

  Further, a polymer material can be mixed in the recording layer. As the polymer material, for example, various materials such as ionomer resin, polyamide resin, vinyl resin, natural polymer, silicone, liquid rubber, or a silane coupling agent may be dispersed and mixed. Alternatively, stabilizers (for example, transition metal complexes), dispersants, flame retardants, lubricants, antistatic agents, surfactants, plasticizers, and the like can be used together for the purpose of improving characteristics.

  The recording layer can be formed by ordinary means such as a vapor deposition method, a sputtering method, a CVD method, or a solution coating method. When the coating method is used, the compounds (A), (B), and (C) are dissolved in an organic solvent to spinner coating, spraying, roller coating, dipping , By a conventional coating method such as spin coating.

  The organic solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, alcohols such as methanol, ethanol, isopropanol, 2,2,3,3-tetrafluoropropanol; acetone, methyl ethyl ketone, Ketones such as cyclohexanone; amides such as N, N-dimethylformamide and N, N-dimethylacetamide; sulfoxides such as dimethyl sulfoxide; ethers such as tetrahydrofuran, dioxane, diethyl ether and ethylene glycol monomethyl ether; methyl acetate; Esters such as ethyl acetate; Aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethane, carbon tetrachloride, and trichloroethane; Aromatics such as benzene, xylene, monochlorobenzene, and dichlorobenzene ; Methoxyethanol, cellosolves such as ethoxyethanol; hexane, pentane, cyclohexane, hydrocarbons such as methylcyclohexane.

  The film thickness of the recording layer is not particularly limited and may be appropriately selected according to the purpose. The thickness is preferably 100 mm (10 nm) to 10 μm, more preferably 200 mm (20 nm) to 2000 mm (200 nm).

-Undercoat layer-
The undercoat layer comprises (1) improved adhesion, (2) a barrier such as water or gas, (3) improved storage stability of the recording layer, (4) improved reflectance, and (5) from a solvent. It is used for the purpose of protecting the substrate and recording layer, and (6) forming guide grooves, guide pits, preformats, and the like.
For the purpose of (1), polymer materials such as ionomer resins, polyamide resins, vinyl resins, natural resins, natural polymers, silicones, liquid rubbers, and various other polymer substances, and silane couplings. An agent or the like can be used. For the purposes (2) and (3), in addition to the polymer material, an inorganic compound such as SiO ₂ , MgF ₂ , SiO, TiO ₂ , ZnO, TiN, SiN, etc., and also a metal or semimetal For example, Zn, Cu, Ni, Cr, Ge, Se, Au, Ag, Al, or the like can be used. For the purpose (4), metals such as Al and Ag, and organic thin films having metallic luster such as methine dyes and xanthene dyes can be used. For the purposes (5) and (6), an ultraviolet curable resin, a thermosetting resin, a thermoplastic resin, or the like can be used.

  There is no restriction | limiting in particular in the film thickness of the said undercoat layer, According to the objective, it can select suitably, 0.01-30 micrometers is preferable and 0.05-10 micrometers is more preferable.

-Reflective layer-
Examples of the material of the reflective layer include metals, semi-metals, and the like that can be obtained with a high reflectivity by themselves, such as Au, Ag, Cr, Ni, Al, Fe, and Sn. Au, Ag, and Al are the most preferable from the viewpoint of rate and productivity, and these metals and metalloids may be used alone or as two kinds of alloys.

The reflective layer can be formed by various vapor deposition methods such as vacuum deposition, sputtering, plasma CVD, photo CVD, ion plating, and electron beam deposition. Among these, the sputtering method is excellent in mass productivity and film quality.
There is no restriction | limiting in particular in the film thickness of the said reflection layer, According to the objective, it can select suitably, 50-5000 mm (5-500 nm) is preferable and 100-3000 mm (10-300 nm) is more preferable.

-Protective layer and substrate surface hard coat layer-
The protective layer or the substrate surface hard coat layer is (1) protection from scratches, dust, dirt, etc. of the recording layer (reflection / absorption layer), (2) improvement in storage stability of the recording layer (reflection / absorption layer), (3) Used for the purpose of improving the reflectance. For these purposes, the materials shown in the undercoat layer can be used. Further, as inorganic materials, for example, SiO, SiO _{2 and the} like can be used, and as organic materials, for example, polymethyl acrylate resin, polycarbonate resin, epoxy resin, polystyrene resin, polyester resin, vinyl resin, cellulose, aliphatic carbonization A heat-softening resin such as hydrogen resin, aromatic hydrocarbon resin, natural rubber, styrene-butadiene resin, chloroprene rubber, wax, alkyd resin, drying oil, and rosin, heat-meltable resin, and ultraviolet curable resin can also be used. Among the above materials, the most preferable example for the protective layer or the substrate surface hard coat layer is an ultraviolet curable resin excellent in productivity.
The thickness of the protective layer or the substrate surface hard coat layer is preferably 0.01 to 30 μm, and more preferably 0.05 to 10 μm.

  In the present invention, as in the case of the recording layer, the undercoat layer, the protective layer, and the substrate surface hard coat layer may further include a stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent, A surfactant, a plasticizer and the like can be contained.

−Protection board−
When the laser beam is irradiated from the side of the protective substrate, the protective substrate must be transparent to the laser beam used, and when used as a simple protective plate, transparency is not an issue. The substrate materials that can be used are exactly the same as the above-mentioned substrate materials, such as polyester resin, acrylic resin, polyamide resin, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, polyimide resin, plastic, glass, ceramics, metal, etc. Can be used.

-Adhesive, adhesive layer-
The adhesive is not particularly limited as long as it is a material that can bond two optical recording media, and can be appropriately selected according to the purpose. An adhesive is preferred.

(Recording / reproducing method of optical recording medium)
The recording / reproducing method of the optical recording medium of the present invention performs at least one of information recording and reproduction by irradiating the optical recording medium of the present invention with a laser beam having an oscillation wavelength of 600 to 720 nm. is there.
Specifically, for recording a semiconductor laser (for example, an oscillation wavelength of 600 to 720 nm) from the substrate side through an objective lens while rotating the optical recording medium at a predetermined linear velocity or a predetermined constant angular velocity. Irradiate the light. By this irradiation light, the recording layer absorbs the light and the temperature rises locally. For example, information is recorded by generating pits and changing their optical characteristics. Information recorded as described above can be reproduced by irradiating a laser beam from the substrate side while rotating the optical recording medium at a predetermined linear velocity and detecting the reflected light.

(Optical recording device)
An optical recording apparatus of the present invention uses the optical recording medium of the present invention as an optical recording medium in an optical recording apparatus that records information on the optical recording medium by irradiating the optical recording medium with light from a light source. .
The optical recording apparatus is not particularly limited and can be appropriately selected according to the purpose. For example, a laser light source such as a semiconductor laser that emits laser light and a laser light emitted from the laser light source are used. A condensing lens for condensing on an optical recording medium mounted on the spindle, a laser light detector for detecting a part of the laser light emitted from the laser light source, a condensing lens and a laser light for the laser light emitted from the laser light source An optical fiber led to the detector is provided, and further means are provided if necessary.

The optical recording apparatus guides laser light emitted from a laser light source to a condensing lens through an optical fiber, and condenses and irradiates the optical recording medium with the condensing lens to perform recording on the optical recording medium. At this time, the optical recording apparatus guides a part of the laser light emitted from the laser light source to the laser light detector, and controls the light amount of the laser light source based on the detection amount of the laser light of the laser light detector.
The laser light detector converts a detected amount of the detected laser light into a voltage or a current and outputs it as a detected amount signal.
Examples of the other means include control means. The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

  Since the optical recording apparatus of the present invention is equipped with the optical recording medium of the present invention that is less dependent on the wavelength shift of the semiconductor laser, it is possible to stably record with high reflectivity and high modulation.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Example 1)
-Production of optical recording media-
A polycarbonate resin substrate having a guide groove having a thickness of 0.6 mm, a depth of 1750 mm (175 nm), a full width at half maximum of 0.25 μm, and a track pitch of 0.74 μm was produced.
Formazan metal chelate compound represented by the following structural formula (A-9, maximum absorption wavelength = 568 nm), squarylium compound represented by the following structural formula (B-4, maximum absorption wavelength = 590 nm), and represented by the following structural formula 2,2,3,3 so that the mass ratio (A-9: B-4: D-5) = 40: 60: 3 of the pentamethine cyanine compound (D-5, maximum absorption wavelength = 707 nm) -A recording layer coating solution was prepared by dissolving in tetrafluoropropanol. The obtained recording layer coating solution was spinner-coated on the substrate to form a recording layer having a thickness of 1000 mm (100 nm). A reflective layer was formed on the recording layer by sputtering so that gold (Au) had a thickness of 1300 mm (130 nm). A protective layer having a thickness of 5 μm was formed on the reflective layer with an acrylic photopolymer, and then a 0.6 mm thick polycarbonate resin flat substrate was adhered with the acrylic photopolymer to produce an optical recording medium.

ただし、ｎは２を表す。

However, n represents 2.

(Example 2)
-Production of optical recording media-
In Example 1, a formazan metal chelate compound represented by the following structural formula (A-5, maximum absorption wavelength = 558 nm), a squarylium compound represented by the following structural formula (B-13, maximum absorption wavelength = 550 nm), and A formazan metal chelate compound (C-1, maximum absorption wavelength = 657 nm) represented by the following structural formula is adjusted to a mass ratio (A-5: B-13: C-1) = 25: 75: 10, An optical recording medium was produced in the same manner as in Example 1 except that a recording layer coating solution was prepared by dissolving in 2,3,3-tetrafluoropropanol.

ただし、ｎは２を表す。

ただし、ｎは２を表す。

However, n represents 2.

However, n represents 2.

(Example 3)
-Production of optical recording media-
In Example 1, formazan metal chelate compound represented by the following structural formula (A-16, maximum absorption wavelength = 545 nm), squarylium compound represented by the following structural formula (B-5, maximum absorption wavelength = 590 nm), and The diarylamine compound (F-3, maximum absorption wavelength = 740 nm) represented by the following structural formula is 2,2 so that the mass ratio (A-16: B-5: F-3) = 10: 90: 7. An optical recording medium was prepared in the same manner as in Example 1 except that a recording layer coating solution was prepared by dissolving in 3,3-tetrafluoropropanol.

Example 4
-Production of optical recording media-
In Example 1, a formazan metal chelate compound represented by the following structural formula (A-13, maximum absorption wavelength = 540 nm), a squarylium compound (B-18, maximum absorption wavelength = 599 nm) represented by the following structural formula, and Pentamethine cyanine compound (D-7, maximum absorption wavelength = 703 nm) represented by the following structural formula is mass ratio (A-13: B-18: D-7) = 50: 50: 0.5 An optical recording medium was produced in the same manner as in Example 1 except that a recording layer coating solution was prepared by dissolving in 2,2,3,3-tetrafluoropropanol.

ただし、Ｐｈはフェニル基を表す。

However, Ph represents a phenyl group.

(Example 5)
-Production of optical recording media-
In Example 1, a formazan metal chelate compound represented by the following structural formula (A-3, maximum absorption wavelength = 564 nm), a squarylium compound represented by the following structural formula (B-7, maximum absorption wavelength = 590 nm), and A phthalocyanine compound (E-6, maximum absorption wavelength = 730 nm) represented by the following structural formula was used in a mass ratio (A-3: B-7: E-6) = 45: 55: 20, 2, 2, An optical recording medium was produced in the same manner as in Example 1 except that a recording layer coating solution was prepared by dissolving in 3,3-tetrafluoropropanol.

ただし、Ｐｈはフェニル基を表し、ｎは２を表す。

However, Ph represents a phenyl group and n represents 2.

(Example 6)
-Production of optical recording media-
In Example 1, formazan metal chelate compound represented by the following structural formula (A-11, maximum absorption wavelength = 572 nm), squarylium compound represented by the following structural formula (B-8, maximum absorption wavelength = 584 nm), and The diarylamine compound (F-9, maximum absorption wavelength = 737 nm) represented by the following structural formula is 2,2 so that the mass ratio (A-11: B-8: F-9) = 40: 60: 5. An optical recording medium was prepared in the same manner as in Example 1 except that a recording layer coating solution was prepared by dissolving in 3,3-tetrafluoropropanol.

ただし、ｎは２を表す。

However, n represents 2.

(Example 7)
-Production of optical recording media-
In Example 1, formazan metal chelate compound represented by the following structural formula (A-1, maximum absorption wavelength = 535 nm), squarylium compound represented by the following structural formula (B-12, maximum absorption wavelength = 606 nm), and A formazan metal chelate compound (C-6, maximum absorption wavelength = 673 nm) represented by the following structural formula is adjusted to a mass ratio (A-1: B-12: C-6) = 30: 70: 2. An optical recording medium was produced in the same manner as in Example 1 except that a recording layer coating solution was prepared by dissolving in 2,3,3-tetrafluoropropanol.

ただし、ｎＰｒは、ｎ−プロピル基を表す。

However, nPr represents an n-propyl group.

(Example 8)
-Production of optical recording media-
In Example 1, a formazan metal chelate compound represented by the following structural formula (A-6, maximum absorption wavelength = 580 nm), a squarylium compound represented by the following structural formula (B-15, maximum absorption wavelength = 588 nm), and A pentamethine cyanine compound (D-14, maximum absorption wavelength = 708 nm) represented by the following structural formula is set to a mass ratio (A-6: B-15: D-14) = 25: 75: 1.5. An optical recording medium was produced in the same manner as in Example 1 except that a recording layer coating solution was prepared by dissolving in 2,2,3,3-tetrafluoropropanol.

ただし、ｎは２を表す。

However, n represents 2.

Example 9
-Production of optical recording media-
In Example 1, formazan metal chelate compound represented by the following structural formula (A-4, maximum absorption wavelength = 585 nm), squarylium compound represented by the following structural formula (B-1, maximum absorption wavelength = 616 nm), and A phthalocyanine compound (E-9, maximum absorption wavelength = 735 nm) represented by the following structural formula was used in a mass ratio (A-4: B-1: E-9) = 25: 75: 15, 2, 2, An optical recording medium was produced in the same manner as in Example 1 except that a recording layer coating solution was prepared by dissolving in 3,3-tetrafluoropropanol.

ただし、Ｐｈはフェニル基を表す。

However, Ph represents a phenyl group.

(Example 10)
-Production of optical recording media-
In Example 1, a formazan metal chelate compound (A-15, maximum absorption wavelength = 575 nm) represented by the following structural formula, a squarylium compound (B-17, maximum absorption wavelength = 600 nm) represented by the following structural formula, and A formazan metal chelate compound (C-10, maximum absorption wavelength = 690 nm) represented by the following structural formula is adjusted so that the mass ratio (A-15: B-17: C-10) = 40: 60: 3 is 2, An optical recording medium was produced in the same manner as in Example 1 except that a recording layer coating solution was prepared by dissolving in 2,3,3-tetrafluoropropanol.

ただし、ｎは２を表す。

ただし、ｎは２を表す。

However, n represents 2.

However, n represents 2.

(Comparative Example 1)
-Production of optical recording media-
In Example 1, a formazan metal chelate compound (A-9, maximum absorption wavelength = 568 nm) represented by the following structural formula, and a squarylium compound (B-4, maximum absorption wavelength = 590 nm) represented by the following structural formula were massed. The recording layer coating solution was prepared by dissolving in 2,2,3,3-tetrafluoropropanol so that the ratio (A-9: B-4) = 40: 60. An optical recording medium was produced.

ただし、ｎは２を表す。

However, n represents 2.

<Recording test>
For each optical recording medium, a semiconductor laser beam having an oscillation wavelength of 658 nm and a beam diameter of 1.0 μm was used for recording while tracking (linear velocity of 3.5 m / sec.), And continuous light from a semiconductor laser having an oscillation wavelength of 658 nm (reproduction power) 0.7 mW), the reproduced waveform was observed, and the reflectivity and recording sensitivity were measured using an optical disk evaluation apparatus (DDU-1000, manufactured by Pulstec). The results are shown in Table 22.
Further, recording and reproduction were similarly performed with a semiconductor laser having an oscillation wavelength of 670 nm, the reproduction waveform was observed, and the reflectance and the recording sensitivity were measured using an optical disk evaluation apparatus (DDU-1000 manufactured by Pulstec). The results are shown in Table 22.

＊（ ）内の数字は、色素の質量比を表す。

* The number in () represents the mass ratio of the pigment.

  The optical recording medium of the present invention can be applied to a write-once DVD disc system using a semiconductor laser having an oscillation wavelength on the short wavelength side and less dependent on the wavelength shift of the semiconductor laser than the conventional optical recording medium. , DVD + R, DVD-R, etc.

FIG. 1 is a graph showing the relationship between the absorption spectrum of the dye mixture used in the recording layer and the recording / reproducing wavelength. 2A to 2D are diagrams illustrating an example of a layer structure of a normal write-once type optical recording medium. 3A to 3C are diagrams illustrating an example of a layer configuration of an optical recording medium for CD-R. 4A and 4B are diagrams illustrating an example of a layer configuration of an optical recording medium for DVD + R or DVD-R.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording layer 3 Undercoat layer 4 Protective layer 5 Hard coat layer 6 Reflective layer 7 Protective substrate 8 Adhesive layer

Claims (16)

  A substrate, and at least a recording layer provided on the substrate, the recording layer comprising at least (A) a formazan metal chelate compound having a maximum absorption wavelength of 500 nm or more and less than 650 nm, and (B) a maximum absorption of an absorption spectrum. An optical recording medium comprising a squarylium compound having a wavelength of 500 nm or more and less than 650 nm, and (C) a compound having a maximum absorption wavelength of an absorption spectrum of 650 nm or more and 800 nm or less.   The optical recording medium according to claim 1, wherein the compound of component (C) is at least one selected from a formazan metal chelate compound, a pentamethine cyanine compound, a phthalocyanine compound, and a diarylamine compound.   The (A) component formazan metal chelate compound and the (B) component squarylium compound have a mass ratio ((A) component: (B) component) of 10:90 to 50:50, and the (C) component compound The optical recording medium according to any one of claims 1 to 2, wherein the added amount is 0.5 to 20 parts by mass with respect to 100 parts by mass in total of the compound of the component (A) and the compound of the component (B). . The formazan metal chelate compound of component (A) and the compound of component (C) are represented by at least one of the following structural formula (1) and the following structural formula (2), and either a metal or a metal compound The optical recording medium according to claim 1, wherein the optical recording medium is a formazan metal chelate compound.

However, in the structural formula (1), ring X represents a heterocyclic ring formed by combining adjacent nitrogen and carbon atoms, and the heterocyclic ring may be further substituted with a substituent. It may be condensed with the ring. Z ₀ represents an atom constituting the ring X. A represents any one of an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an alkenyl group, an alkoxycarbonyl group, and a heterocyclic group, and these may be further substituted with a substituent. B represents any of an alkyl group, an alkenyl group, and an aryl group, and these may be further substituted with a substituent.

However, in the structural formula (2), the ring Y and the ring Z may be the same as or different from each other, and a heterocyclic ring formed by combining an adjacent nitrogen atom and carbon atom together. And the heterocyclic ring may be further substituted with a substituent and may be condensed with another ring. Z ₁ and Z ₂ represent atoms constituting the ring Y and the ring Z, respectively. A ₁ and A ₂ may be the same as or different from each other, and are any one of an alkyl group, an aryl group, an alkylcarbonyl group, an arylcarbonyl group, an alkenyl group, an alkoxycarbonyl group, and a heterocyclic group. These may be further substituted with a substituent. B ₁ and B ₂ may be the same as or different from each other, and represent an alkylene group, an alkenylene group, or an arylene group, and these may be further substituted with a substituent. W represents —CH ₂ — or —SO ₂ —. n is an integer of 0 or 1.   5. The metal or the metal compound is at least one selected from vanadium, manganese, iron, cobalt, nickel, copper, zinc, palladium, an oxide of the metal, and a halide of the metal. An optical recording medium according to 1. 6. The optical recording medium according to claim 1, wherein the component (B) is a squarylium compound represented by any one of the following structural formula (3) and the following structural formula (4).

However, in the structural formula (3), R ¹ and R ² may be the same as or different from each other, and are any of a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, and a heterocyclic group. These may be further substituted with a substituent, and R ¹ and R ² may be combined with the adjacent nitrogen atom to form a heterocyclic ring which may have a substituent. . R ³ represents a substituent represented by any one of the following structural formula (3-1) and the following structural formula (3-2).

However, in the structural formula (3-1), R ⁴ and R ⁵ may be the same as or different from each other, and may be a hydrogen atom or an alkyl group that may have a substituent. And these may be combined with the adjacent nitrogen atom to form an optionally substituted heterocycle. R ⁶ , R ⁷ , R ⁸ and R ⁹ may be the same as or different from each other, and represent any one of a hydrogen atom, a halogen atom, a hydroxyl group, an alkyl group, and an alkoxy group, Further, it may be substituted with a substituent. R ⁴ and R ⁶ or R ⁵ and R ⁷ together with adjacent N—C—C may form a heterocyclic ring which may have a substituent.

However, Q < ₁ > represents either a carbon atom or a nitrogen atom in said structural formula (3-2). R ¹⁰ and R ¹¹ may be the same as or different from each other, and each represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and these are further substituted with a substituent. Also good. However, if _{Q 1} is a nitrogen ^{atom, R 11} is not present.
R ¹² represents any one of a hydrogen atom, an alkyl group, an aryl group, and an aralkyl group, and these may be further substituted with a substituent. R ¹³ and R ¹⁴ may be the same as or different from each other, and each represents a hydrogen atom, a halogen atom, an alkyl group, or an alkoxy group, and these are further substituted with a substituent. It may have a heterocyclic ring which may have a substituent together with two adjacent carbon atoms, an alicyclic hydrocarbon ring which may have a substituent, or a substituent. An aromatic ring may be formed.

In the Structural Formula (4), Q ₂ represents one of a carbon atom and a nitrogen atom. R ¹⁵ represents any one of a hydrogen atom, an alkyl group, an aryl group, and a heterocyclic group, and these may be further substituted with a substituent. R ¹⁶ represents any one of a hydrogen atom, a halogen atom, an amino group, an alkyl group, an alkoxy group, an aralkyl group, an aryl group, and a heterocyclic group, and these may be further substituted with a substituent. R ¹⁷ and R ¹⁸ may be the same as or different from each other, and each represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and these are further substituted with a substituent. Alternatively, together with the adjacent carbon atom, a heterocyclic ring which may have a substituent or an alicyclic hydrocarbon ring which may have a substituent may be formed. However, when _{Q 2} is a nitrogen ^{atom, R 18} is not present.
R ¹⁹ represents any one of a hydrogen atom, an alkyl group, an aralkyl group, and an aryl group, and these may be further substituted with a substituent. R ²⁰ represents any one of a halogen atom, a nitro group, a cyano group, an alkyl group, an aralkyl group, an aryl group, and an alkoxy group, and these may be further substituted with a substituent. n represents an integer of 0 to 4. When n is 2 to 4, R ²⁰ may be the same as or different from each other, and two carbons adjacent to each other two R ²⁰ are adjacent to each other. An aromatic ring which may have a substituent may be formed together with the atom. The optical recording medium according to claim 1, wherein the component (C) is a pentamethine cyanine compound represented by the following structural formula (5).

However, in the structural formula (5), R ²¹ represents any of a hydrogen atom, a halogen atom, an alkyl group, and an alkenyl group, which may be further substituted with a substituent. R ²² and R ²³ may be the same as or different from each other, and each represents an alkyl group that may have a substituent. Q ⁻ represents an anion. The optical recording medium according to claim 1, wherein the component (C) is a phthalocyanine compound represented by the following structural formula (6).

However, in the structural formula (6), R ^{24 to} R ²⁷ may be the same as or different from each other, and are a hydrogen atom, an alkyl group, an aryl group, an alkenyl group, an alkylsulfinyl group, an arylsulfinyl group. Represents any of a group, an alkylsulfonyl group, an arylsulfonyl group, an alkyloxysulfonyl group, an aryloxysulfonyl group, an alkoxy group, an arylcarbonyloxy group, and a heterocyclic group, which may be further substituted with a substituent. . q1~q4 represents an integer of 0 to 4, when q1~q4 is 2 to 4, each ^R 24 ^{to R 27} may be the same or may be different from one another. M ₁ represents any one of two hydrogen atoms, a metal atom, a metal compound, a metalloid atom, and a metalloid compound. M ₁ is V═O and L ₁ —Si—L ₂ (where L ₁ and L ₂ may be the same as or different from each other, and may be a hydrogen atom, an alkyl group, an aryl group, or an alkenyl group). Represents any of a group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an aryloxysulfonyl group, an arylcarbonyloxy group, and a heterocyclic group, which may be further substituted with a substituent. 9) The optical recording medium according to claim 8, The optical recording medium according to claim 1, wherein the component (C) is a diarylamine compound represented by the following structural formula (7).

However, in the structural formula (7), R ²⁸ and R ²⁹ may be the same as or different from each other, and represent a hydrogen atom or an alkyl group that may have a substituent. R ³⁰ represents any one of a hydrogen atom, an alkyl group, and an alkylamino group, and these may be further substituted with a substituent. Q ₃ ⁻ represents an anion.   The refractive index n of the recording layer single layer with respect to light in the wavelength range of the recording / reproducing wavelength ± 10 nm is 1.5 ≦ n ≦ 3.0, and the extinction coefficient k is 0.02 ≦ k ≦ 0.3. Item 11. The optical recording medium according to any one of Items 1 to 10.   The optical recording medium according to claim 11, wherein a recording / reproducing wavelength is 600 to 720 nm.   The optical recording medium according to any one of claims 1 to 12, wherein a track pitch on the substrate is 0.7 to 0.8 µm, and a guide groove width is 0.18 to 0.40 µm in half width.   The optical recording medium according to claim 1, further comprising a reflective layer, wherein the reflective layer contains any one selected from gold, silver, copper, aluminum, and alloys thereof.   15. A recording / reproducing method for an optical recording medium, wherein the optical recording medium according to claim 1 is recorded / reproduced at a recording wavelength of 600 to 720 nm. 15. An optical recording apparatus for recording information on an optical recording medium by irradiating the optical recording medium with light from a light source, wherein the optical recording medium is the optical recording medium according to any one of claims 1 to 14. An optical recording apparatus.

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