JP3933350B2 - Optical recording medium - Google Patents

Description

（式中、Ｚは、チアゾール環、ベンゾチアゾール環、オキサゾール環、ベンゾオキサゾール環、ピラゾール環、ベンゾピラゾール環、イミダゾール環、ベンゾイミダゾール環、オキサジアゾール環、トリアゾール環、チアジアゾール環、ピリダジン環、ピリミジン環、ピラジン環、トリアジン環、ナフタリジン環、フラクタジン環、シンノリン環、キナゾリン環、キノキサリン環、フェナジン環から選択された複素環を表わし、該複素環は、アルキル基、アルコキシ基、チオアルコキシ基、置換アミノ基、アリル基、アリルオキシ基、アニリノ基、ケト基等の置換基を有していてもよい。
Ａは、アルキル基、アラルキル基、アリル基、シクロヘキシル基を表わし、アルキル基、アルコキシ基、ハロゲン基、ケト基、カルボキシル基またはそのエステル、ニトリル基、ニトロ基等の置換基を有していてもよい。
Ｂは、アリール基を表わし、アルキル基、アルコキシ基、ハロゲン基、カルボキシル基またはそのエステル、ニトリル基、ニトロ基等の置換基を有していてもよい。
Ｍは、２価の金属原子を表わす。
ｎは、Ｍに配位するホルマザン配位子の数を表わす。）
」、（２）「前記一般式（Ｉ）中、Ｍが鉄、コバルト、ニッケル、銅、亜鉛、パラジウムであることを特徴とする前記第（１）項に記載の光記録媒体。」、（３）「前記記録層が前記一般式（Ｉ）以外に５５０〜６３０ｎｍに最大吸収波長を有する光吸収性色素との混合層からなることを特徴とする前記第（１）項又は前記第（２）項に記載の光記録媒体。」、（４）「前記記録層が、前記一般式（Ｉ）化合物の最大吸収波長が前記光吸収性色素の最大吸収波長の−５０ｎｍより長波長となるよう構成された混合層からなることを特徴とする前記第（３）項に記載の光記録媒体。」、（５）「前記光吸収性色素がポリメチン色素、スクアリリウム色素またはアゾ金属キレート色素である前記第（３）項または前記第（４）項に記載の光記録媒体。」、（６）「前記ポリメチン色素がシアニン色素であることを特徴とする前記第（５）項に記載の光記録媒体。」である。
【００１０】
ここで、前記第（１）項は本発明のホルマザン金属キレート色素を用いた高密度光記録媒体としての基本構造および材料構成であり、前記第（２）項は、前記第（１）項の良好な光記録媒体を得る一般式（Ｉ）の最適化学構造である。前記第（３）項は本発明のホルマザン金属色素を光安定材として用いる基本材料構成で、前記第（４）項は最も効率の良い光安定材として用いる基本構成、前記第（５）項は前記第（３）項、前記第（４）項の良好な光記録媒体を得る最適構成材料であり、前記第（６）項は前記第（５）項のポリメチン色素の最適構成材料である。
【００１１】
基板上に反射層を有する光記録媒体としてコンパクトディスク（ＣＤ）規格に対応した記録可能なＣＤ（ＣＤ−Ｒ）が商品化されている。記録層に波長７７０〜８３０ｎｍのレーザ光を照射し、記録層に物理あるいは化学的な変化を起こす、反射光を検出することにより、情報を記録再生する。最近、より短波長の半導体レーザの開発が進み、波長６３０〜６８０ｎｍの赤色半導体レーザが実用化されている。記録再生用レーザの短波長化によりビーム径をより小さくすることが可能で、高密度の光記録媒体が可能となる。本発明は、波長６３０〜６８０ｎｍで記録再生可能な記録材料を用いた高密度光記録媒体（ＤＶＤ−Ｒ）に関するものである。
【００１２】
＜記録体構成＞
本発明の記録媒体の構成としては追記型光ディスクの構造（基板上に記録層を設けたものを２枚貼り合わせたいわゆるエアーサンドイッチ構造）としてもよく、ＣＤ−Ｒ構造（基板上に記録層、反射層、保護層）としてもよく、ＣＤ−Ｒ構造を貼り合わせた構造でもよい。
【００１３】
＜基板＞
用いる基板としては基板側より記録再生を行なう場合のみ使用レーザに対して透明でなければならず、記録層側から記録、再生を行なう場合基板は透明である必要はない。
基板材料としては例えば、ポリエステル、アクリル樹脂、ポリアミド、ポリカーボネート樹脂、ポリオレフィン樹脂、フェノール樹脂、エポキシ樹脂、ポリイミドなどのプラスチックまたは、ガラス、セラミックあるいは、金属などを用いることができる。なお、基板の表面にトラッキング用の案内溝や、案内ピット、さらにアドレス信号などのプリフォーマットなどが形成されていてもよい。
【００１４】
＜記録層＞
記録層はレーザ光の照射により何らかの光学的変化を生じさせ、その変化により情報を記録するものであって、この記録層中には本発明の一般式（Ｉ）で示される化合物を少なくとも１種含有してなることが必要である。
【００１５】
【化３】

（式中、Ｚは、チアゾール環、ベンゾチアゾール環、オキサゾール環、ベンゾオキサゾール環、ピラゾール環、ベンゾピラゾール環、イミダゾール環、ベンゾイミダゾール環、オキサジアゾール環、トリアゾール環、チアジアゾール環、ピリダジン環、ピリミジン環、ピラジン環、トリアジン環、ナフタリジン環、フラクタジン環、シンノリン環、キナゾリン環、キノキサリン環、フェナジン環から選択された複素環を表わし、該複素環は、アルキル基、アルコキシ基、チオアルコキシ基、置換アミノ基、アリル基、アリルオキシ基、アニリノ基、ケト基等の置換基を有していてもよい。
Ａは、アルキル基、アラルキル基、アリル基、シクロヘキシル基を表わし、アルキル基、アルコキシ基、ハロゲン基、ケト基、カルボキシル基またはそのエステル、ニトリル基、ニトロ基等の置換基を有していてもよい。
Ｂは、アリール基を表わし、アルキル基、アルコキシ基、ハロゲン基、カルボキシル基またはそのエステル、ニトリル基、ニトロ基等の置換基を有していてもよい。
Ｍは、２価の金属原子を表わす。
ｎは、Ｍに配位するホルマザン配位子の数を表わす。）
【００１６】
Ｚとしては、光学特性、保存安定性、耐光性の面から、特にピリダジン環、ピリミジン環、ピラジン環、トリアジン環が好ましい。
【００１７】
Ｂの具体例としては、フェニル基、ペンタレニル基、インデニル基、ナフチル基、アズレニル基、ヘプタレニル基、ビフェニレニル基、as-インダセニル基、s-インダセニル基、アセナフタレニル基、フルオレニル基、フェナレニル基、フェナントラニル基、アントラニル基、フルオラセニル基、アセフェナントラレニル基、アセアントリレン基、トリフェニレニル基、ピレニル基、クリセニル基、ナフタセニル基等が挙げられる。
【００１８】
金属原子の具体例は、チタン、バナジウム、クロム、マンガン、鉄、コバルト、ニッケル、銅、亜鉛、ジルコニウム、ニオブ、モリブデン、テクネニウム、ルテニウム、ロジウム、パラジウム等が挙げられるが、光学特性、保存安定性および光安定性の面から、特に鉄、コバルト、ニッケル、銅、亜鉛、パラジウムが好ましい。
【００１９】
上記ハロゲン原子の具体例は、フッ素、塩素、臭素、ヨウ素等が挙げられる。上記アルキル基の具体例は、メチル基、エチル基、n-プロピル基、n-ブチル基、n-ペンチル基、n-ヘキシル基、n-ヘプチル基、n-オクチル基、n-ノニル基、n-デシル基等の一級アルキル基、イソブチル基、イソアミル基、2-メチルブチル基、2-メチルペンチル基、3-メチルペンチル基、4-メチルペンチル基、2-エチルブチル基、2-メチルヘキシル基、3-メチルヘキシル基、4-メチルヘキシル基、5-メチルヘキシル基、2-エチルペンチル基、3-エチルペンチル基、2-メチルヘプチル基、3-メチルヘプチル基、4-メチルヘプチル基、5-メチルヘプチル基、2-エチルヘキシル基、3-エチルヘキシル基、イソプロピル基、sec-ブチル基、1-エチルプロピル基、1-メチルブチル基、1,2-ジメチルプロピル基、1-メチルヘプチル基、1-エチルブチル基、1,3-ジメチルブチル基、1,2-ジメチルブチル基、1-エチル-2-メチルプロピル基、1-メチルヘキシル基、1-エチルヘプチル基、1-プロピルブチル基、1-イソプロピル-2-メチルプロピル基、1-エチル-2-メチルブチル基、1-エチル-2-メチルブチル基、1-プロピル-2-メチルプロピル基、1-メチルヘプチル基、1-エチルヘキシル基、1-プロピルペンチル基、1-イソプロピルペンチル基、1-イソプロピル-2-メチルブチル基、1-イソプロピル-3-メチルブチル基、1-メチルオクチル基、1-エチルヘプチル基、1-プロピルヘキシル基、1-イソブチル-3-メチルブチル基等の二級アルキル基、ネオペンチル基、tert-ブチル基、tert-ヘキシル基、tert-アミル基、tert-オクチル基等の三級アルキル基、シクロヘキシル基、4-メチルシクロヘキシル基、4-エチルシクロヘキシル基、4-tert-ブチルシクロヘキシル基、4-(2-エチルヘキシル)シクロヘキシル基、ボルニル基、イソボルニル基(アダマンタン基)等のシクロアルキル基等が挙げられる。更に、これら一級および二級アルキル基は、水酸基、ハロゲン原子、ニトロ基、カルボキシ基、シアノ基、置換または未置換のアリール基、置換または未置換の複素環残基等を以て置換されていてもよく、また酸素、硫黄、窒素等の原子を介して前記のアルキル基で置換されていてもよい。酸素を介して置換されているアルキル基としては、メトキシメチル基、メトキシエチル基、エトキシメチル基、エトキシエチル基、ブトキシエチル基、エトキシエトキシエチル基、フェノキシエチル基、メトキシプロピル基、エトキシプロピル基、ピペリジノ基、モルホリノ基等が、硫黄を介して置換されているアルキル基としては、メチルチオエチル基、エチルチオエチル基、エチルチオプロピル基、フェニルチオエチル基等が、窒素を介して置換されているアルキル基としては、ジメチルアミノエチル基、ジエチルアミノエチル基、ジエチルアミノプロピル基等が挙げられる。
【００２０】
上記アリール基の具体例は、フェニル基、ペンタレニル基、インデニル基、ナフチル基、アズレニル基、ヘプタレニル基、ビフェニレニル基、as-インダセニル基、s-インダセニル基、アセナフタレニル基、フルオレニル基、フェナレニル基、フェナントラニル基、アントラニル基、フルオラセニル基、アセフェナントラレニル基、アセアントリレン基、トリフェニレニル基、ピレニル基、クリセニル基、ナフタセニル基等が挙げられる。更に、これらアリール基は、水酸基、ハロゲン原子、ニトロ基、カルボキシ基、シアノ基、置換または未置換のアリール基、置換または未置換の複素環残基等を以て置換されていてもよく、また酸素、硫黄、窒素等の原子を介して前記のアルキル基で置換されていてもよい。
【００２１】
上記アルコキシ基の具体例は、酸素原子に直接置換または未置換のアルキル基が結合されているものであればよく、アルキル基の具体例としては前述の具体例を挙げることができ、上記アリールオキシ基の具体例は、酸素原子に直接置換または未置換のアリール基が結合されているものであればよく、アリールの具体例としては前述の具体例を挙げることができる。
【００２２】
記録層の形成に当たって本発明の色素１種、または２種以上の組み合わせで用いてもよい。さらに、本発明の上記色素は光学特性、記録感度、信号特性などの向上の目的で他の有機色素および金属、金属化合物と混合または積層化して用いてもよい。有機色素の例としては、ポリメチン色素、ナフタロシアニン色素、フタロシアニン色素、スクアリリウム色素、クロコニウム色素、ピリリウム色素、ナフトキノン色素、アントラキノン色素(インダンスレン色素)、キサンテン色素、トリフェニルメタン色素、アズレン色素、テトラヒドロコリン色素、フェナンスレン色素、トリフェノチアジン色素およびその金属錯体化合物などが挙げられる。
【００２３】
金属、金属化合物の例としてはＩｎ、Ｔｅ、Ｂｉ、Ｓｅ、Ｓｂ、Ｇｅ、Ｓｎ、Ａｌ、Ｂｅ、ＴｅＯ₂、ＳｎＯ、Ａｓ、Ｃｄなどが挙げられ、それぞれを分散混合あるいは積層の形態で用いることができる。
【００２４】
また、光安定化材として用いる場合は、５５０ｎｍ〜６３０ｎｍに吸収最大波長を有する色素と本発明の色素を混合して使用する。
この場合ホルマザン色素は、上記色素の最大吸収波長−５０ｎｍより長波長に吸収を持つことがその効率上好ましい。−５０ｎｍより短波長の場合はその光安定化能が低下する。５５０ｎｍ〜６３０ｎｍに吸収最大波長のある色素の好ましい例としては、ポリメチン色素、スクアリリウム色素、クロコニウム色素、ピリリウム色素、ナフトキノン色素、アントラキノン色素(インダンスレン系)、キサンテン色素、トリフェニルメタン色素、テトラヒドロコリン色素、フェナンスレン色素、トリフェノチアジン色素、アゾ金属キレート色素等があり、光学特性からポリメチン色素、スクアリリウム色素、アゾ金属キレート色素が特に好ましい。
【００２５】
さらに、上記染料中に高分子材料、例えばアイオノマー樹脂、ポリアミド樹脂、ビニル系樹脂、天然高分子、シリコーン、液状ゴムなどの種々の材料もしくはシランカップリング剤などを分散混合してもよく、特性改良の目的で安定剤(例えば遷移金属錯体)、分散剤、難燃剤、滑剤、帯電防止剤、界面活性剤、可塑剤などと分散混合してもよい。
【００２６】
記録層の形成方法としては蒸着、スパッタリング、ＣＶＤまたは溶剤塗布などの通常の手段によって行なうことができる。塗布法を用いる場合には上記染料などを有機溶剤に溶解して、スプレー、ローラーコーティグ、ディピングおよび、スピンコーティングなどの慣用のコーティング法によって行なうことができる。用いられる有機溶媒としては一般にメタノール、エタノール、イソプロパノールなどのアルコール類、アセトン、メチルエチルケトン、シクロヘキサノンなどのケトン類、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミドなどのアミド類、ジメチルスルホキシドなどのスルホキシド類、テトラヒドロフラン、ジオキサン、ジエチルエーテル、エチレングリコールモノメチルエーテルなどのエーテル類、酢酸メチル、酢酸エチルなどのエステル類、クロロホルム、塩化メチレン、ジクロロエタン、四塩化炭素、トリクロロエタンなどの脂肪族ハロゲン化炭化水素類、ベンゼン、キシレン、モノクロロベンゼン、ジクロロベンゼンなどの芳香族類、メトキシエタノール、エトキシエタノールなどのセロソルブ類、ヘキサン、ペンタン、シクロヘキサン、メチルシクロヘキサンなどの炭化水素類などが挙げられる。記録層の膜厚は１００Å〜１０μｍ好ましくは２００Å〜２０００Åが適当である。
【００２７】
＜下引き層＞
下引き層は▲１▼接着性の向上、▲２▼水またはガスなどのバリアー、▲３▼記録層の保存安定性の向上、▲４▼反射率の向上、▲５▼溶剤からの基板の保護、▲６▼案内溝、案内ピット、プレフォーマットの形成などを目的として使用される。▲１▼の目的に対しては高分子材料、例えば、アイオノマー樹脂、ポリアミド樹脂、ビニル樹脂、天然樹脂、天然高分子、シリコーン、液状ゴムなどの種々の高分子化合物および、シランカップリング剤などを用いることができ、▲２▼および▲３▼の目的に対しては上記高分子材料以外に無機化合物、例えば、ＳｉＯ、ＭｇＦ、ＳｉＯ₂、ＴｉＯ、ＺｎＯ、ＴｉＮ、ＳｉＮなどがあり、さらに金属または半金属、例えば、Ｚｎ、Ｃｕ、Ｎｉ、Ｃｒ、Ｇｅ、Ｓｅ、Ａｕ、Ａｇ、Ａｌなどを用いることができる。また、▲４▼の目的に対しては金属、例えば、Ａｌ、Ａｕ、Ａｇ等や、金属光沢を有する有機薄膜、例えば、メチン染料、キサンテン系染料などを挙げることができ、▲５▼、▲６▼の目的に対しては紫外線硬化樹脂、熱硬化樹脂、熱可塑性樹脂等を用いることができる。下引き層の膜厚としては０．０１〜３０μｍ好ましくは、０．０５〜１０μｍが適当である。
【００２８】
＜金属反射層＞
金属反射層は単体で高反射率の得られる腐食されにくい金属、半金属等が挙げられ、材料例としてはＡｕ、Ａｇ、Ｃｒ、Ｎｉ、Ａｌ、Ｆｅ、Ｓｎなどが挙げられるが、反射率、生産性の点からＡｕ、Ａｇ、Ａｌが最も好ましく、これらの金属、半金属は単独で使用してもよく、２種の合金としてもよい。膜形成法としては蒸着、スパッタリングなどが挙げられ、膜厚としては５０〜５０００Å好ましくは１００〜３０００Åである。
【００２９】
＜保護層、基板面ハードコート層＞
保護層および基板面ハードコート層は▲１▼記録層(反射吸収層)を傷、ホコリ、汚れ等から保護する、▲２▼記録層(反射吸収層)の保存安定性の向上、▲３▼反射率の向上等を目的として使用される。これらの目的に対しては、前記下引き層に示した材料を用いることができる。また、無機材料として、ＳｉＯ、ＳｉＯ₂なども用いることができ、有機材料としてポリメチルアクリレート、ポリカーボネート、エポキシ樹脂、ポリスチレン、ポリエステル樹脂、ビニル樹脂、セルロース、脂肪族炭化水素樹脂、天然ゴム、スチレンブタジエン樹脂、クロロプレンゴム、ワックス、アルキッド樹脂、乾性油、ロジン等の熱軟化性、熱溶融性樹脂も用いることができる。上記材料のうち最も好ましい例としては生産性に優れた紫外線硬化樹脂である。保護層または基板面ハードコート層の膜厚は０．０１〜３０μｍ好ましくは０．０５〜１０μｍが適当である。本発明において、前記下引き層、保護層、および、基板面ハードコート層には記録層の場合と同様に、安定剤、分散剤、難燃剤、滑剤、帯電防止剤、界面活性剤、可塑剤等を含有させることができる。
【００３０】
化合物例を表１に示す。
【００３１】
【表１−１】

【００３２】
【表１−２】

【００３３】
【表１−３】

【００３４】
【表１−４】

【００３５】
【表１−５】

【００３６】
【実施例】
以下、実施例により本発明を詳細に説明する。
［実施例１］
深さ１６００Å、半値幅０．３０μｍ、トラックピッチ０．８μｍの案内溝を有する厚さ０．６ｍｍの射出成形ポリカーボネート基板上に、化合物例Ｎｏ.１５をテトラフルオロプロパノール溶液に溶解した液をスピンナー塗布し厚さ、７００Åの有機色素層を形成し、次いで、スパッタ法により金２０００Åの反射層を設け、さらにその上にアクリル系フォトポリマーにて１０μｍの保護層を設け記録媒体とした。
【００３７】
［実施例２、３、４、５、６、７、８］
実施例１で化合物Ｎｏ.１５の代わりにそれぞれ、化合物Ｎｏ．９、１１、１２、１８、２４、３２、４０を用い、実施例６と全く同様に記録媒体を得た。
【００３８】
［比較例１、２］
実施例１で有機薄膜として、化合物例Ｎｏ.８の代わりに下記（比−１）、（比−２）の化合物を用いて記録媒体とした。
【００３９】
【化４】

【００４０】
【化５】

【００４１】
＜記録条件＞
この記録体に発振波長６３５ｎｍの半導体レーザ光を用い、トラッキングしながらＥＦＭ信号(線速３．０ｍ／ｓｅｃ、最短マーク長０．４μｍ)を記録し、発振波長６５０ｎｍの半導体レーザの連続光（再生パワー０．７ｍＷで再生し、反射率、Ｃ／Ｎを測定した。
耐光テスト：タングステンランプ、５万ルクス、２０時間照射
【００４２】
評価結果を表２に示す。
【００４３】
【表２】

【００４４】
［実施例９、１０］
厚さ１．２ｍｍの射出成形ポリカーボネート平板上に、前記化合物(比−１)と化合物Ｎｏ.３６とを重量比(１０／１．５)および重量比(１０／３)の混合物をテトラフルオロプロパノール溶解し、スピンナー塗布して、厚さ１０００Åの有機色素層を形成した。この色素薄膜をタングステンランプ、５万ルクス下に置き、色素の吸光度の変化を測定した。
【００４５】
［実施例１１、１２］
実施例９、１０で化合物(比−１)の代わりに、(比−２)を用い全く同様に色素薄膜を得た。
【００４６】
［比較例３］
実施例９で化合物(比−１)のみの色素薄膜としたもの。
【００４７】
［比較例４］
実施例１１で化合物(比−２)のみの色素薄膜としたもの。
【００４８】
評価結果を表３に示す。
【００４９】
【表３】

【００５０】
化合物Ｎｏ．８、１３、１６、１９、２９、３５、４６でも同様に顕著な光安定化効果を得た。
【００５１】
【発明の効果】
以上、詳細且つ具体的な説明から明らかなように、本発明のホルマザン金属キレートは、塗布によるコーティングが可能で、耐光性、保存安定性に優れた高屈折率で高反射率および高変調度メディアが提供でき、またポリメチン色素、スクアリリウム色素およびアゾ金属キレート色素との混合により、それら単独の場合に比較し耐光性に優れたメディアが提供できる。
請求項１により６５０ｎｍ以下の波長域のレーザ光で高密度記録、再生が可能で耐光性、保存安定性に優れた光情報記録媒体が提供でき、請求項２はその最も好ましい化学構造でより優れた光情報記録媒体が提供できる。
請求項３により光安定化材として用いる光情報記録媒体が提供でき、請求項４は光安定化材としてより効率の良く作用する基本構成で、請求項５はその好ましい材料構成を示し、優れた光情報記録媒体が提供でき、請求項６により好ましい材料構成を示し、より優れた光情報記録媒体が提供できる。[0001]
BACKGROUND OF THE INVENTION
The present invention generally relates to an information recording medium, and in particular, by irradiating a light beam, optical changes such as transmittance and reflectance of a recording material are caused to record and reproduce information. The present invention relates to an information recording medium that can be performed and additionally written, for example, a data write-once optical disc and a write-once compact disc (DVD-R).
[0002]
[Prior art]
As conventional techniques for DVD-R recording materials, polymethine dyes used as recording materials are disclosed in JP-A-10-83577, JP-A-10-119434, JP-A-10-149583, and JP-A-10-188339. JP-A-10-278426 and polymethine dye + light-stabilizing material as recording materials are disclosed in JP-A-10-109475, JP-A-10-109476, and JP-A-10-10. No. 134413, JP-A-10-151861, and JP-A-10-166739, and those using an azo metal chelate dye as a recording material are disclosed in JP-A-8-295811 and JP-A-8-295812. JP-A-9-327277, JP-A-9-39394, JP-A-10-6650, JP-A-1 -58828, JP-A-10-157293, JP-A-10-157300, JP-A-10-188340, JP-A-10-188341, and other dyes + metal reflective layers. The recording materials are described in JP-A-8-169182, JP-A-8-209010, and JP-A-9-58130, and those using a formazan metal chelate dye as the recording material. This is described in JP-A-8-295079, JP-A-9-193546, JP-A-10-152623, and JP-A-10-154350.
[0003]
Currently, DVD-R is being developed as a next generation large capacity optical disk. Elemental technologies for improving the recording capacity require the development of recording materials for miniaturization of recording pits, the adoption of image compression technology represented by MPEG2, and the shortening of the wavelength of a semiconductor laser for recording pit reading. is there.
Up until now, only 670nm AlGaInP laser diodes for bar code readers and measuring instruments have been commercialized as red wavelength semiconductor lasers. It is being used in the optical storage market. In the case of a DVD drive, the light source is standardized with two wavelengths of a laser diode of a 635 nm band and a 650 nm band. For high-density recording, it is desirable that the wavelength is shorter, and the wavelength of 635 nm is preferable as a drive for additional recording media. On the other hand, a read-only DVD-ROM drive is commercialized with a wavelength of ˜650 nm.
[0004]
Under these circumstances, the most preferable DVD-R media is a media (DVD-R) that can be recorded and reproduced at a wavelength of 635 nm and can be reproduced at a wavelength of 650 nm, and has excellent light resistance and storage stability. A recording material that can be recorded and reproduced by an optical pickup using the following laser is desired. Recently, polymethine dyes and azo metal chelate dyes have been actively developed as recording materials.
[0005]
Among polymethine dyes, cyanine dyes and squarylium dyes, in particular, are excellent in optical properties and can provide satisfactory signal properties, but they are extremely poor in light resistance and cannot be put into practical use by themselves. As an improvement, the development of light stabilizers is underway, but no one that has both light stabilization ability and signal characteristics has been found.
The azo metal chelate dye also has satisfactory signal characteristics but does not have sufficient light resistance.
[0006]
On the other hand, formazan metal chelate dyes are known to have extremely high light stability and have been tried to be applied as optical recording materials. However, none of them has a long absorption wavelength and is not suitable as a recording material for DVD-R. . Although the application of cyanine dyes as light stabilizers has also been attempted, the light stabilization mechanism is based on excitation energy transfer from the main dye to the light stabilizer, so that more efficient light stabilizers are mainly used. It is necessary to have absorption ability at an energy level closer to the excitation energy of the dye. In this sense, the conventional formazan metal dye has an absorption wavelength that is too long, and has not been able to exhibit sufficient light stabilization ability.
[0007]
[Problems to be solved by the invention]
Therefore, the object of the present invention is higher in solubility in organic solvents applicable to a high-density optical disk system using a semiconductor laser having an oscillation wavelength at a shorter wavelength, and superior in light resistance and storage stability, compared to the conventional system. It is to provide a recording material for DVD-R.
Another object of the present invention is to provide a light stabilizer that improves the light stability of polymethine dyes, squarylium dyes, and azo metal dyes that exhibit excellent signal characteristics as recording dyes for DVD-R.
[0008]
[Means for Solving the Problems]
As a result of investigations, the present inventors have found that a recording layer mainly composed of a formazan metal dye having a specific structure has the above characteristics, and can be applied to a high-density optical disk system using a semiconductor laser having an oscillation wavelength of 700 nm or less. The optical recording medium has high light resistance.
That is, the present invention provides: (1) “Light having a recording layer provided directly on a substrate or via an undercoat layer, and further provided with a reflective layer, a protective layer or an adhesive layer, and a second substrate as necessary. An optical recording medium, wherein the recording layer contains at least one compound represented by the following general formula (I).
[0009]
[Chemical 2]

Wherein Z is a thiazole ring, benzothiazole ring, oxazole ring, benzoxazole ring, pyrazole ring, benzopyrazole ring, imidazole ring, benzimidazole ring, oxadiazole ring, triazole ring, thiadiazole ring, pyridazine ring, pyrimidine Represents a heterocyclic ring selected from a ring, a pyrazine ring, a triazine ring, a naphthalidine ring, a fructazine ring, a cinnoline ring, a quinazoline ring, a quinoxaline ring, and a phenazine ring, and the heterocyclic ring is an alkyl group, an alkoxy group, a thioalkoxy group, a substituted group You may have substituents, such as an amino group, an allyl group, an allyloxy group, an anilino group, and a keto group.
A represents an alkyl group, an aralkyl group, an allyl group, or a cyclohexyl group, and may have a substituent such as an alkyl group, an alkoxy group, a halogen group, a keto group, a carboxyl group or an ester thereof, a nitrile group, or a nitro group. Good.
B represents an aryl group, an alkyl group, an alkoxy group, a halogen group, a carboxyl group or an ester thereof, nitrile group, which may have a substituent such as a nitro group.
M represents a divalent metal atom.
n represents the number of formazan ligands coordinated to M. )
( 2 ) “The optical recording medium according to item (1), wherein M is iron, cobalt, nickel, copper, zinc, palladium in the general formula (I)”. 3 ) The item (1) or the item ( 2 ), wherein the recording layer comprises a mixed layer with a light-absorbing dye having a maximum absorption wavelength at 550 to 630 nm in addition to the general formula (I). ) the optical recording medium according to claim. "(4)" the recording layer, so that the maximum absorption wavelength of the formula (I) compound is the longer wavelength -50nm of the maximum absorption wavelength of the light absorbing dye the optical recording medium according to the first mode (3), characterized in that it consists configured mixed layer. "(5)" wherein the light absorbing dye is a polymethine dye, squarylium dye, or an azo metal chelate dye Item ( 3 ) or item ( 4 ) ( 6 ) “The optical recording medium according to ( 5 ) above, wherein the polymethine dye is a cyanine dye”.
[0010]
Here, the item (1) is a basic structure and material structure as a high-density optical recording medium using the formazan metal chelate dye of the present invention, and the item (2) is the item of the item (1). It is the optimum chemical structure of the general formula (I) for obtaining a good optical recording medium. The ( 3 ) term is a basic material configuration using the formazan metal dye of the present invention as a light stabilizer, the ( 4 ) term is a basic configuration used as the most efficient light stabilizer, and the ( 5 ) term is The optimal constituent material for obtaining the good optical recording medium of the ( 3 ) term and the ( 4 ) term, and the ( 6 ) term is the optimal constituent material of the polymethine dye of the ( 5 ) term.
[0011]
A recordable CD (CD-R) corresponding to the compact disc (CD) standard has been commercialized as an optical recording medium having a reflective layer on a substrate. Information is recorded and reproduced by irradiating the recording layer with laser light having a wavelength of 770 to 830 nm and detecting reflected light that causes a physical or chemical change in the recording layer. Recently, development of shorter wavelength semiconductor lasers has progressed, and red semiconductor lasers with wavelengths of 630 to 680 nm have been put into practical use. By shortening the wavelength of the recording / reproducing laser, the beam diameter can be further reduced, and a high-density optical recording medium can be realized. The present invention relates to a high-density optical recording medium (DVD-R) using a recording material that can be recorded and reproduced at a wavelength of 630 to 680 nm.
[0012]
<Recording body configuration>
The structure of the recording medium of the present invention may be a write-once optical disk structure (a so-called air sandwich structure in which two recording layers are provided on a substrate), or a CD-R structure (a recording layer on a substrate, A reflective layer, a protective layer), or a structure in which a CD-R structure is bonded.
[0013]
<Board>
The substrate to be used must be transparent to the laser used only when recording / reproduction is performed from the substrate side, and the substrate need not be transparent when recording / reproduction is performed from the recording layer side.
As the substrate material, for example, plastic such as polyester, acrylic resin, polyamide, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, polyimide, glass, ceramic, or metal can be used. Note that a guide groove for tracking, a guide pit, and a preformat such as an address signal may be formed on the surface of the substrate.
[0014]
<Recording layer>
The recording layer causes some optical change upon irradiation with laser light, and records information by the change. In the recording layer, at least one compound represented by the general formula (I) of the present invention is recorded. It is necessary to contain.
[0015]
[Chemical 3]

Wherein Z is a thiazole ring, benzothiazole ring, oxazole ring, benzoxazole ring, pyrazole ring, benzopyrazole ring, imidazole ring, benzimidazole ring, oxadiazole ring, triazole ring, thiadiazole ring, pyridazine ring, pyrimidine Represents a heterocyclic ring selected from a ring, a pyrazine ring, a triazine ring, a naphthalidine ring, a fructazine ring, a cinnoline ring, a quinazoline ring, a quinoxaline ring, and a phenazine ring, and the heterocyclic ring is an alkyl group, an alkoxy group, a thioalkoxy group, a substituted group You may have substituents, such as an amino group, an allyl group, an allyloxy group, an anilino group, and a keto group.
A represents an alkyl group, an aralkyl group, an allyl group, or a cyclohexyl group, and may have a substituent such as an alkyl group, an alkoxy group, a halogen group, a keto group, a carboxyl group or an ester thereof, a nitrile group, or a nitro group. Good.
B represents an aryl group, an alkyl group, an alkoxy group, a halogen group, a carboxyl group or an ester thereof, nitrile group, which may have a substituent such as a nitro group.
M represents a divalent metal atom.
n represents the number of formazan ligands coordinated to M. )
[0016]
It is a Z, optical science properties, storage stability, in terms of light resistance, particularly a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring are preferred.
[0017]
Specific examples of B include a phenyl group, a pentarenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptaenyl group, a biphenylenyl group, an as-indacenyl group, an s-indacenyl group, an acenaphthalenyl group, a fluorenyl group, a phenalenyl group, a phenanthrenyl group, Anthranyl group, fluoracenyl group, acephenanthrenyl group, acanthrylene group, triphenylenyl group, pyrenyl group, chrycenyl group, naphthacenyl group and the like can be mentioned.
[0018]
Specific examples of metal atoms include titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, zirconium, niobium, molybdenum, technenium, ruthenium, rhodium, palladium, etc., but optical properties, storage stability From the viewpoint of light stability, iron, cobalt, nickel, copper, zinc and palladium are particularly preferable.
[0019]
Specific examples of the halogen atom include fluorine, chlorine, bromine, iodine and the like. Specific examples of the alkyl group include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n Primary alkyl group such as -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-methyl Heptyl, 2-ethylhexyl, 3-ethylhexyl, isopropyl, sec-butyl, 1-ethylpropyl, 1-methylbutyl, 1,2-dimethylpropyl, 1-methylheptyl, 1-ethylbutyl 1,3-dimethylbutyl group, 1,2- Methylbutyl 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-ethyl-2-methylbutyl group, 1-propyl-2-methylpropyl group, 1-methylheptyl group, 1-ethylhexyl group, 1-propylpentyl group, 1-isopropylpentyl group, 1-isopropyl-2-methylbutyl group Secondary alkyl groups such as 1-isopropyl-3-methylbutyl group, 1-methyloctyl group, 1-ethylheptyl group, 1-propylhexyl group, 1-isobutyl-3-methylbutyl group, neopentyl group, tert-butyl group Tertiary alkyl groups such as tert-hexyl group, tert-amyl group, tert-octyl group, cyclohexyl group, 4-methylcyclohexyl group, 4-ethylcyclohexyl group, 4-tert-butylcyclohexyl group, 4- (2- Echi And cycloalkyl groups such as (ruhexyl) cyclohexyl group, bornyl group, isobornyl group (adamantane group) and the like. Further, these primary and secondary alkyl groups may be substituted with a hydroxyl group, a halogen atom, a nitro group, a carboxy group, a cyano group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic residue, and the like. In addition, the alkyl group may be substituted with an atom such as oxygen, sulfur or nitrogen. Examples of the alkyl group substituted through oxygen include a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an ethoxyethyl group, a butoxyethyl group, an ethoxyethoxyethyl group, a phenoxyethyl group, a methoxypropyl group, an ethoxypropyl group, As an alkyl group in which a piperidino group, a morpholino group, or the like is substituted through sulfur, a methylthioethyl group, an ethylthioethyl group, an ethylthiopropyl group, a phenylthioethyl group, or the like is substituted through nitrogen Examples of the alkyl group include a dimethylaminoethyl group, a diethylaminoethyl group, and a diethylaminopropyl group.
[0020]
Specific examples of the aryl group include a phenyl group, a pentarenyl group, an indenyl group, a naphthyl group, an azulenyl group, a heptaenyl group, a biphenylenyl group, an as-indacenyl group, an s-indacenyl group, an acenaphthalenyl group, a fluorenyl group, a phenalenyl group, and a phenanthrenyl group. , Anthranyl group, fluoracenyl group, acephenanthrenyl group, aceanthrylene group, triphenylenyl group, pyrenyl group, chrycenyl group, naphthacenyl group and the like. Further, these aryl groups may be substituted with a hydroxyl group, a halogen atom, a nitro group, a carboxy group, a cyano group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic residue, and the like, The alkyl group may be substituted via an atom such as sulfur or nitrogen.
[0021]
Specific examples of the alkoxy group are not particularly limited as long as a direct or unsubstituted alkyl group is bonded to an oxygen atom. Specific examples of the alkyl group include the above-described specific examples. Specific examples of the group may be those in which a substituted or unsubstituted aryl group is bonded directly to the oxygen atom, and specific examples of the aryl include the above-described specific examples.
[0022]
In forming the recording layer, the dye of the present invention may be used alone or in combination of two or more. Furthermore, the dye of the present invention may be used by mixing or laminating with other organic dyes, metals, and metal compounds for the purpose of improving optical characteristics, recording sensitivity, signal characteristics, and the like. Examples of organic dyes include polymethine dyes, naphthalocyanine dyes, phthalocyanine dyes, squarylium dyes, croconium dyes, pyrylium dyes, naphthoquinone dyes, anthraquinone dyes (indanthrene dyes), xanthene dyes, triphenylmethane dyes, azulene dyes, tetrahydro dyes Examples thereof include choline dyes, phenanthrene dyes, triphenothiazine dyes and metal complex compounds thereof.
[0023]
Examples of metals and metal compounds include In, Te, Bi, Se, Sb, Ge, Sn, Al, Be, TeO ₂ , SnO, As, and Cd. Can do.
[0024]
Moreover, when using as a light stabilizer, the pigment | dye which has the absorption maximum wavelength in 550 nm-630 nm, and the pigment | dye of this invention are mixed and used.
In this case, it is preferable that the formazan dye has an absorption at a wavelength longer than the maximum absorption wavelength −50 nm of the dye. When the wavelength is shorter than −50 nm, the light stabilization ability is lowered. Preferred examples of the dye having the maximum absorption wavelength at 550 nm to 630 nm include polymethine dye, squarylium dye, croconium dye, pyrylium dye, naphthoquinone dye, anthraquinone dye (indanthrene), xanthene dye, triphenylmethane dye, tetrahydrocholine Examples thereof include dyes, phenanthrene dyes, triphenothiazine dyes, and azo metal chelate dyes, and polymethine dyes, squarylium dyes, and azo metal chelate dyes are particularly preferable from the viewpoint of optical characteristics.
[0025]
In addition, polymer materials such as ionomer resins, polyamide resins, vinyl resins, natural polymers, silicones, liquid rubber, or silane coupling agents may be dispersed and mixed in the above dyes to improve characteristics. For this purpose, it may be dispersed and mixed with a stabilizer (for example, a transition metal complex), a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, a plasticizer and the like.
[0026]
The recording layer can be formed by ordinary means such as vapor deposition, sputtering, CVD, or solvent coating. When the coating method is used, the above-described dye or the like can be dissolved in an organic solvent, and the coating can be performed by a conventional coating method such as spraying, roller coating, dipping, or spin coating. As the organic solvent to be used, alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and sulfoxides such as dimethyl sulfoxide , Ethers such as tetrahydrofuran, dioxane, diethyl ether and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogenated hydrocarbons such as chloroform, methylene chloride, dichloroethane, carbon tetrachloride and trichloroethane, Aromatics such as benzene, xylene, monochlorobenzene, dichlorobenzene, cellosolves such as methoxyethanol and ethoxyethanol, hexane, penta , Cyclohexane, and hydrocarbons such as methylcyclohexane. The film thickness of the recording layer is 100 to 10 μm, preferably 200 to 2000 μm.
[0027]
<Underlayer>
The undercoat layer is (1) improved adhesion, (2) a barrier such as water or gas, (3) improved storage stability of the recording layer, (4) improved reflectivity, and (5) the substrate from the solvent. Used for the purpose of protection, (6) formation of guide grooves, guide pits, preformats, etc. For the purpose of (1), various polymer compounds such as ionomer resin, polyamide resin, vinyl resin, natural resin, natural polymer, silicone, liquid rubber, and silane coupling agent are used for the purpose of (1). For the purposes of (2) and (3), there are inorganic compounds, for example, SiO, MgF, SiO ₂ , TiO, ZnO, TiN, SiN, etc. in addition to the above polymer materials, and also metals or Semimetals such as Zn, Cu, Ni, Cr, Ge, Se, Au, Ag, Al, etc. can be used. For the purpose of (4), metals such as Al, Au and Ag, and organic thin films having a metallic luster such as methine dyes and xanthene dyes can be mentioned. For the purpose 6), an ultraviolet curable resin, a thermosetting resin, a thermoplastic resin, or the like can be used. The thickness of the undercoat layer is 0.01 to 30 μm, preferably 0.05 to 10 μm.
[0028]
<Metal reflective layer>
Examples of the metal reflective layer include a metal, a semi-metal, and the like that are not easily corroded to obtain high reflectivity, and examples of materials include Au, Ag, Cr, Ni, Al, Fe, Sn, etc. Au, Ag, and Al are most preferable from the viewpoint of productivity, and these metals and metalloids may be used alone or as two kinds of alloys. Examples of the film forming method include vapor deposition and sputtering, and the film thickness is 50 to 5000 mm, preferably 100 to 3000 mm.
[0029]
<Protective layer, substrate surface hard coat layer>
The protective layer and the substrate hard coat layer are: (1) protect the recording layer (reflection / absorption layer) from scratches, dust, dirt, etc., (2) improve the storage stability of the recording layer (reflection / absorption layer), and (3) Used for the purpose of improving reflectivity. For these purposes, the materials shown in the undercoat layer can be used. In addition, SiO, SiO ₂ or the like can be used as the inorganic material, and polymethyl acrylate, polycarbonate, epoxy resin, polystyrene, polyester resin, vinyl resin, cellulose, aliphatic hydrocarbon resin, natural rubber, styrene butadiene as the organic material. Thermosoftening and heat melting resins such as resins, chloroprene rubber, waxes, alkyd resins, drying oils and rosins can also be used. The most preferable example among the above materials is an ultraviolet curable resin excellent in productivity. The film thickness of the protective layer or the substrate surface hard coat layer is 0.01 to 30 μm, 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-side hard coat layer have a stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, and a plasticizer. Etc. can be contained.
[0030]
Compound examples are shown in Table 1.
[0031]
[Table 1-1]

[0032]
[Table 1-2]

[0033]
[Table 1-3]

[0034]
[Table 1-4]

[0035]
[Table 1-5]

[0036]
【Example】
Hereinafter, the present invention will be described in detail by way of examples.
[Example 1]
Spinner coating of a solution obtained by dissolving Compound Example No. 15 in a tetrafluoropropanol solution on an injection molded polycarbonate substrate having a depth of 1600 mm, a half width of 0.30 μm and a track groove of 0.8 μm and a thickness of 0.6 mm. Then, an organic dye layer having a thickness of 700 mm was formed, and then a gold 2000 mm reflective layer was formed by sputtering, and a protective layer of 10 μm was further formed thereon with an acrylic photopolymer to obtain a recording medium.
[0037]
[Examples 2, 3, 4, 5, 6, 7, 8]
In Example 1, Compound No. 15 was used instead of Compound No. 15, respectively. 9, 11, 12, 18, 24, 32, 40 were used to obtain a recording medium exactly as in Example 6.
[0038]
[Comparative Examples 1 and 2]
The organic thin film in Example 1 was used as a recording medium by using the following compounds (ratio-1) and (ratio-2) instead of compound example No. 8.
[0039]
[Formula 4]

[0040]
[Chemical formula 5]

[0041]
<Recording conditions>
A semiconductor laser beam with an oscillation wavelength of 635 nm is recorded on this recording medium, and an EFM signal (linear speed: 3.0 m / sec, minimum mark length: 0.4 μm) is recorded while tracking. Reproduction was performed at a power of 0.7 mW, and reflectance and C / N were measured.
Light resistance test: Tungsten lamp, 50,000 lux, 20 hours irradiation [0042]
The evaluation results are shown in Table 2.
[0043]
[Table 2]

[0044]
[Examples 9 and 10]
A mixture of the compound (ratio-1) and compound No. 36 in a weight ratio (10 / 1.5) and a weight ratio (10/3) on a 1.2 mm thick injection-molded polycarbonate flat plate was added to tetrafluoropropanol. It melt | dissolved and spinner apply | coated and the organic pigment | dye layer of thickness 1000mm was formed. The dye thin film was placed under a tungsten lamp at 50,000 lux, and the change in absorbance of the dye was measured.
[0045]
[Examples 11 and 12]
In Examples 9 and 10, a dye thin film was obtained in the same manner using (Ratio-2) instead of Compound (Ratio-1).
[0046]
[Comparative Example 3]
What was made into the pigment | dye thin film only of a compound (ratio-1) in Example 9. FIG.
[0047]
[Comparative Example 4]
What was made into the pigment | dye thin film only of a compound (ratio-2) in Example 11. FIG.
[0048]
The evaluation results are shown in Table 3.
[0049]
[Table 3]

[0050]
Compound No. Similarly, a remarkable light stabilization effect was obtained with 8, 13, 16, 19, 29, 35, and 46.
[0051]
【The invention's effect】
As described above, the formazan metal chelate of the present invention can be coated by coating, has a high refractive index, a high reflectance, and a high degree of modulation medium that is excellent in light resistance and storage stability. In addition, by mixing with a polymethine dye, a squarylium dye, and an azo metal chelate dye, a medium excellent in light resistance as compared with the case of using them alone can be provided.
According to claim 1, an optical information recording medium capable of high-density recording and reproduction with a laser beam having a wavelength region of 650 nm or less and having excellent light resistance and storage stability can be provided, and claim 2 is superior in its most preferable chemical structure. An optical information recording medium can be provided.
According to claim 3, an optical information recording medium used as a light stabilizing material can be provided. Claim 4 is a basic structure which works more efficiently as a light stabilizing material, and claim 5 shows a preferable material structure, which is excellent. An optical information recording medium can be provided, and a more preferable optical information recording medium can be provided by showing a preferable material structure according to claim 6 .

Claims (6)

In an optical recording medium in which a recording layer is provided directly on a substrate or via an undercoat layer, and further a reflective layer, a protective layer or an adhesive layer and a second substrate are provided on the recording layer as necessary, An optical recording medium comprising at least one compound represented by the formula (I).

Wherein Z is a thiazole ring, benzothiazole ring, oxazole ring, benzoxazole ring, pyrazole ring, benzopyrazole ring, imidazole ring, benzimidazole ring, oxadiazole ring, triazole ring, thiadiazole ring, pyridazine ring, pyrimidine Represents a heterocyclic ring selected from a ring, a pyrazine ring, a triazine ring, a naphthalidine ring, a fructazine ring, a cinnoline ring, a quinazoline ring, a quinoxaline ring, and a phenazine ring, and the heterocyclic ring is an alkyl group, an alkoxy group, a thioalkoxy group, a substituted group You may have substituents, such as an amino group, an allyl group, an allyloxy group, an anilino group, and a keto group.
A represents an alkyl group, an aralkyl group, an allyl group, or a cyclohexyl group, and may have a substituent such as an alkyl group, an alkoxy group, a halogen group, a keto group, a carboxyl group or an ester thereof, a nitrile group, or a nitro group. Good.
B represents an aryl group, an alkyl group, an alkoxy group, a halogen group, a carboxyl group or an ester thereof, nitrile group, which may have a substituent such as a nitro group.
M represents a divalent metal atom.
n represents the number of formazan ligands coordinated to M. ) 2. The optical recording medium according to claim 1, wherein in the general formula (I), M is iron, cobalt, nickel, copper, zinc, or palladium. The optical recording medium according to claim 1 or 2, wherein the recording layer is a mixed layer of a light absorbing dye having a maximum absorption wavelength in 550~630nm in addition to the general formula (I). Claim 3 wherein the recording layer is, the maximum absorption wavelength of the formula (I) compound is characterized by comprising a mixed layer that is configured to be longer wavelength than -50nm of the maximum absorption wavelength of the light absorbing dye An optical recording medium according to 1. The optical recording medium according to claim 3 or 4 , wherein the light absorbing dye is a polymethine dye, a squarylium dye, or an azo metal chelate dye. 6. The optical recording medium according to claim 5 , wherein the polymethine dye is a cyanine dye.