JP3623039B2 - Optical recording medium - Google Patents

Description

〔式中、Ｍ、Ｘ¹〜Ｘ⁴、Ｒ¹〜Ｒ⁴、ｋ、ｌ、ｍ及びｎは、それぞれ以下のものを表わす。
Ｍ：２個の水素原子、又は酸素原子若しくはハロゲン原子を有してもよい２価、３価若しくは４価の金属原子、又は（−ＯＲ⁵）ｏ基、（−ＯＳｉＲ⁶Ｒ⁷Ｒ⁸）ｏ基、（−ＯＰＯＲ⁹Ｒ¹⁰）ｏ基若しくは（−ＯＣＯＲ¹¹）ｏ基を有する金属原子、Ｒ⁵〜Ｒ¹¹：各々独立に水素原子、置換若しくは未置換の１価の脂肪族炭化水素基又は置換若しくは未置換の１価の芳香族炭化水素基、ｏ：０〜２の整数、Ｘ¹〜Ｘ⁴：各々独立に水素原子、置換若しくは未置換のアルキル基、Ｒ¹〜Ｒ⁴：各々独立に水素原子、置換若しくは未置換の直鎖若しくは分岐のアルキル基、ｋ、ｌ、ｍ、ｎ：各々独立に０〜４の整数、但し、ｋ、ｌ、ｍ、ｎが同時に０になることはない。なお、ｋ、ｌ、ｍ、ｎが３以下の場合、ベンゼン環の他の置換基は水素原子又はハロゲン原子である。）
第二に、上記第一に記載した光記録媒体において、前記一般式（Ｉ）で示される化合物が、ｋ、ｌ、ｍ及びｎの各々が独立に０〜２の整数であり、且つその置換基の置換位置が１又は４である光記録媒体が提供される。第三に、上記第一又は第二に記載した光記録媒体において、前記記録層が前記一般式（Ｉ）で示される化合物の少なくとも１種と６８０ｎｍ〜７５０ｎｍに最大吸収波長を有する有機色素とを含有してなることを特徴とする光記録媒体が提供される。第四に、上記第三に記載した光記録媒体において、前記６８０ｎｍ〜７５０ｎｍに最大吸収波長を有する有機色素がペンタメチンのシアニン色素、フタロシアニン色素及びアゾ金属キレート色素の少なくとも１種である光記録媒体が提供される。本発明の光記録媒体においては、必要に応じて記録層にアルミニウム又は金からなる反射層、紫外線硬化型樹脂からなる保護層を設けることができる。
【０００７】
本発明の光記録媒体は、前記一般式（Ｉ）で示される化合物の少なくとも１種を含有する記録層を設けたことから、７００ｎｍ以下の波長域のレーザ光で記録、再生が可能で、しかも耐光性且つ保存安定性に優れたものとなり、また別の態様では、前記一般式（Ｉ）で示される少なくとも１種の化合物と、６８０〜７５０ｎｍに最大吸収波長を有する有機色素との混合物からなる記録層を設けたことから、現状システムでのＣＤ−Ｒ媒体として使用でき、しかも次世代の高密度光ディスクシステムとなっても、記載された情報を再生することが可能なものとなる。
【０００８】
【発明の実施の形態】
以下、本発明を詳しく説明する。
本発明の光記録媒体は、記録層中に前記一般式（Ｉ）で示される化合物の少なくとも１種を含有してなることを特徴とする。
まず、本発明で使用する前記一般式（Ｉ）で示される化合物について説明すると、前記一般式（Ｉ）において、Ｍは２個の水素原子、又は酸素原子若しくはハロゲン原子を有してもよい２価、３価若しくは４価の金属原子、又は（−ＯＲ^５）ｏ基、（−ＯＳｉＲ^６Ｒ^７Ｒ^８）ｏ基、（−ＯＰＯＲ^９Ｒ^１０）ｏ基若しくは（−ＯＣＯＲ^１１）ｏ基を有する金属原子を表わす。
ここに、Ｒ^５〜Ｒ^１１は各々独立に水素原子、置換若しくは未置換の１価の脂肪族炭化水素基又は置換若しくは未置換の１価の芳香族炭化水素基を表わし、ｏは０〜２の整数を表わす。Ｘ^１〜Ｘ^４は各々独立に水素原子、置換若しくは未置換のアルキル基を表わし、Ｒ^１〜Ｒ^４は各々独立に水素原子、置換若しくは未置換の直鎖若しくは分岐のアルキル基を表わす。また、ｋ、ｌ、ｍ、ｎは各々独立に０〜４の整数を表わし、ただ、ｋ、ｌ、ｍ、ｎが同時に０になることはない。なお、ｋ、ｌ、ｍ、ｎが３以下の場合、ベンゼン環の他の置換基は水素原子又はハロゲン原子である。
【０００９】
特に、一般式（Ｉ）中の［ＣＸ^１（ＣＯＯＲ^１）_２］ｋ等で表わされる置換基の置換数が１又は２であり、且つ置換位置が１又は４であるいわゆるα置換体は、吸収波長を調整する際有利で、且つ薄膜化した時、会合阻止による薄膜の高屈折率化が実現でき、記録媒体とした時の高反射率化が計れる。
【００１０】
また、一般式（Ｉ）中、特にｋ＝ｌ＝ｍ＝ｎ＝１の場合は、以下に示す（Ａ）〜（Ｄ）の４つの異性体が存在し、記録膜の吸収帯をやや広げることができ、記録波長マージンや記録パワーマージンを広げることに寄与することがしばしばある。
【化２】

【化３】

【化４】

【化５】

上式中、Ｙ^１〜Ｙ^４は［ＣＸ^１（ＣＯＯＲ^１）_２］ｋ〜［ＣＸ^４（ＣＯＯＲ^４）_２］ｎを表わす。
【００１１】
一般式（Ｉ）中、Ｘ^１〜Ｘ^４のアルキル基の具体例としては、例えば、メチル基、エチル基、ｎ−プロピル基、ｎ−ブチル基、イソブチル基、ｎ−ペンチル基、ネオペンチル基、イソアミル基、ｎ−ヘキシル基、ｎ−オクチル基、ｎ−ノニル基、ｎ−デシル基、ｎ−ドデシル基等の一級アルキル基；イソプロピル基、ｓｅｃ−ブチル基等の二級アルキル基が挙げられる。また、これらアルキル基はハロゲン原子等で特定位置が置換されていてもよい。
【００１２】
一般式（Ｉ）中、Ｒ^１〜Ｒ^４のアルキル基の具体例としては、例えば、メチル基、エチル基、ｎ−プロピル基、ｎ−ブチル基、イソブチル基、ｎ−ペンチル基、ネオペンチル基、イソアミル基、ｎ−ヘキシル基、ｎ−オクチル基、ｎ−ノニル基、ｎ−デシル基、ｎ−ドデシル基等の一級アルキル基；イソプロピル基、ｓｅｃ−ブチル基等の二級アルキル基；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が挙げられる。また、これらアルキル基はハロゲン原子等で特定位置が置換されていてもよい。
【００１３】
一般式（Ｉ）中、Ｍの具体例としては、水素原子；Ｃａ、Ｍｇ、Ｚｕ、Ｃｕ、Ｎｉ、Ｐｄ、Ｆｅ、Ｐｂ、Ｃｏ、Ｐｔ、Ｃｄ、Ｒｕなどの二価の金属；Ａｌ、Ｉｎ、Ｆｅ、Ｇａ、Ｔｌ、Ｍｎなどの三価金属のハロゲン化物、ヒドロキシル化物、アルコキシ化物、トリアルキルシロキシ化物など；及びＳｉ、Ｔｉ、Ｓｎ、Ｃｒ、Ｇａ、Ｓｎ、Ｍｎ、Ｚｒ、Ｖなどの四価金属のハロゲン化物、ヒドロキシル化物、アルコキシ化物、トリアルキルシロキシ化物、酸化物などが挙げられる。また、前記Ｒ^５〜Ｒ^１１の定義中、１価の脂肪族炭化水素基としては、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、ｓｅｃ−ブチル基、ｔｅｒｔ−ブチル基、アミル基、ヘキシル基、オクチル基、デシル基、ドデシル基、オクタデシル基等のアルキル基や、ビニル基、アリル基、イソプロペニル基、１−ブテニル基、２−ブテニル基、２−ペンテニル基等のアルケニル基などが挙げられる。１価の芳香族炭化水素基としては、フェニル基、ベンジル基などが挙げられる。また、それらの置換基としては、フッ素、塩素、臭素などのハロゲン原子、三フッ化炭素基、シアノ基、エステル基などが挙げられる。
【００１４】
前記一般式（Ｉ）で表わされる化合物の具体例としては、例えば表１−（１）〜１−（２）に示されるものが挙げられる。
【００１５】
【表１−（１）】

【００１６】
【表１−（２）】

【００１７】
また、記録層においては、前記したように、前記一般式（Ｉ）で示される少なくとも１種の化合物と、６８０〜７５０ｎｍに最大吸収波長を有する有機色素との混合物を主成分とすることにより、現状システムで記録再生が可能であるとともに、次世代システムにおいても再生のみは可能なＣＤ−Ｒ記録媒体となる。この場合の６８０〜７５０ｎｍに最大吸収波長を有する色素としては、ペンタメチンのシアニン色素、フタロシアニン色素及びアゾ金属キレート色素が好ましい。
【００１８】
ペンタメチンのシアニン色素の好ましい例としては、下記一般式（ＩＩ）で示されるものが挙げられる。
【化６】

式中、Ｒ^２１、Ｒ^２２は炭素数１〜３のアルキル基、Ｒ^２３、Ｒ^２４は炭素数１〜６の置換又は未置換のアルキル基、Ｘは酸アニオンを表わす。なお、芳香族環は他の芳香族環と縮合されていてもよく、また、アルキル基、ハロゲン原子、アルコキシ基又はアシル基で置換されていてもよい。
【００１９】
フタロシアニン色素の好ましい例としては、下記一般式（ＩＩＩ−１）若しくは（ＩＩＩ−２）で示されるものが挙げられる。
【化７】

式中、Ｍ^１はＮｉ、Ｐｄ、Ｃｕ、Ｚｎ、Ｃｏ、Ｍｎ、Ｆｅ、ＴｉＯ又はＶＯを、Ｘ^５〜Ｘ^８はそれぞれ独立に置換位置α位の−ＯＲ又は−ＳＲを、Ｒは置換されていてもよい炭素数３〜１２の直鎖、分岐若しくは脂環式アルキル基又は同じく置換されていてもよいアリール基を表わす。Ｘ^５〜Ｘ^８以外のベンゼン環の置換基は水素原子又はハロゲン原子である。
【００２０】
【化８】

式中、Ｍ^２は、Ｓｉ、Ｇｅ、Ｉｎ、又はＳｎを、Ｘ^９〜Ｘ^１２はそれぞれ独立に置換位置α位の−ＯＲ又は−ＳＲを、Ｒは置換されていてもよい炭素数３〜１２の直鎖、分岐若しくは脂環式アルキル基又は同じく置換されていてもよいアリール基を、Ｙ^５、Ｙ^６は−ＯＳｉＲ^２５Ｒ^２６Ｒ^２７、−ＯＣＯＲ^２５Ｒ^２６Ｒ^２７、又は−ＯＰＯＲ^２５Ｒ^２６Ｒ^２７を表わし、Ｒ^２５〜Ｒ^２７はそれぞれ独立に炭素数１〜１０のアルキル基又はアリール基を表わす。Ｘ^９〜Ｘ^１２以外のベンゼン環の置換基は、水素原子又はハロゲン原子である。
【００２１】
また、アゾ金属キレート色素の好ましい例としては、下記一般式（ＩＶ）で示されるアゾ系化合物と金属とのアゾ金属キレート化合物の１種又は２種以上が挙げられ、、金属の好ましい例としては、Ｎｉ、Ｐｔ、Ｐｄ、Ｃｏ、Ｃｕ、Ｚｎなどが挙げられる。
【化９】

式中、Ａはそれが結合している炭素原子及び窒素原子と一緒になって複素環を形成する残基を表わし、Ｂはそれが結合している二つの炭素原子と一緒になって芳香環又は複素環を形成する残基を表わし、またＸは活性水素を有する基を表わす。
【００２２】
本発明の前記一般式（Ｉ）で示される少なくとも１種の色素と前記一般式（ＩＩ）〜（ＩＶ）で示される少なくとも１種の色素とを併用する場合の重量組成比は、本発明色素／〔（ＩＩ）〜（ＩＶ）の色素〕＝１０／１００〜９０／１００、好ましくは４０／１００〜２０／１００である。また、両色素を併用した場合の記録層の膜厚は５００Å〜５μｍ、好ましくは１０００Å〜５０００Åである。
【００２３】
次に、本発明の記録媒体の構成について述べる。
図１は、本発明の記録媒体に適用し得る層構成例を示す図で、これは追記型光ディスクの例である。基板１の上に、必要に応じて下引き層３を介して、記録層２を設け、更に必要に応じ保護層４が設けられている。また、必要に応じて基板１の下にハードコート層を設けることができる。
図２は、本発明の記録媒体に適用し得る別のタイプの層構成例を示す図で、これはＣＤ−Ｒメディアの例である。図１の構成の記録層２の上に反射層６が設けられている。
なお、本発明の記録媒体は、図１及び図２に示した構成の記録層（有機薄膜層）を内側にして、他の基板と空間を介して密封したエアーサンドイッチ構造にしてもよく、また保護層を介して接着した貼合せ構造にしてもよい。
【００２４】
次に、構成各層の必要特性及びその構成材料について述べる。
１）基板
基板の必要特性としては、基板側より記録再生を行なう場合には使用レーザ光に対して透明でなければならないが、記録層側から記録再生を行なう場合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、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、更にアドレス信号などのプレフォーマットが形成されていてもよい。
【００２５】
２）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できるものであって、この記録層中には前記一般式（Ｉ）で示される化合物の少なくとも１種、場合により更に前記一般式（ＩＩ）〜（ＩＶ）で示される色素の少なくとも１種が含有されている必要がある。更に、これらの色素は光学特性、記録感度、信号特性の向上のため、他の有機色素及び金属、金属化合物と混合又は積層化して用いることも、もちろん可能である。この場合の他の有機色素としては、ポリメチン色素、ナフタロシアニン系、フタロシアニン系、スクアリリウム系、クロコニウム系、ピリリウム系、ナフトキノン系、アントラキノン（インダンスレン）系、キサンテン系、トリフェニルメタン系、アズレン系、テトラヒドロコリン系、フェナンスレン系、トリフェノチアジン系染料、及び金属錯体化合物などが挙げられる。また金属、金属化合物例としては、Ｉｎ、Ｔｅ、Ｂｉ、Ｓｅ、Ｓｂ、Ｇｅ、Ｓｎ、Ａｌ、Ｂｅ、ＴｅＯ_２、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。更に、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若しくはシランカップリング剤などを分散混合しても良いし、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、可塑剤などと一緒に用いることができる。
【００２６】
記録層の形成は蒸着、スパッタリング、ＣＶＤ又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、ローラーコーティング、ディッピング又はスピンコーティングなどの慣用のコーティング法で行なうことができる。用いられる有機溶剤としては、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−ジメチルアセトアミド、Ｎ，Ｎ−ジメチルホルム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、あるいはメトキシエタノール、エトキシエタノールなどのセルソルブ類、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】
３）下引き層
下引き層は、▲１▼接着性の向上、▲２▼水又はガスなどに対するバリヤー、▲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、ビニル系樹脂、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及びシランカップリング剤などを用いることができ、▲２▼及び▲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_２、ＭｇＦ_２、ＳｉＯ、ＴｉＯ_２、ＺｎＯ、ＴｉＮ、ＳｉＮなどがあり、更に金属又は半金属、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などや、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用いることができ、▲５▼及び▲６▼の目的に対しては、紫外線硬化樹脂、熱硬化樹脂、熱可塑性樹脂などを用いることができる。下引き層の膜厚は０．０１〜３０μｍ、好ましくは０．０５〜１０μｍが適当である。
【００２９】
５）基板面ハードコート層
基板面ハードコート層は、(ｉ)記録層（反射吸収層）を傷、埃、汚れなどから保護する、（ｉｉ）記録層（反射吸収層）の保存安定性の向上、（ｉｉｉ）反射率の向上などを目的として使用される。これらの目的に対しては、前記の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なども用いることもでき、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、ロジンなどの熱軟化性、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ものは、生産性に優れた紫外線硬化樹脂である。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。
【００３０】
本発明において、前記の下引き層、保護層及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、可塑剤などを含有させることができる。
【００３１】
【実施例】
以下実施例について本発明を説明するが、本発明これらに限定されるものではない。
【００３２】
実施例１
実施例１
厚さ１．２μｍのポリメチルメタクリレート基板上にフォトポリマーにて、深さ１２００Å、半値幅０．４μｍ、トラックピッチ１．４μｍの案内溝を形成した基板上に、化合物具体例Ｎｏ．１の１，２−ジクロロエタン溶液をスピンナー塗布し、厚さ８００Åの記録層を設けて記録媒体を得た。
【００３３】
実施例２〜８
実施例１において、化合物具体例Ｎｏ．１の代わりに、化合物具体例Ｎｏ．２、Ｎｏ．４、Ｎｏ．６、Ｎｏ．７、Ｎｏ．９、Ｎｏ．１４、Ｎｏ．２１を用いたこと以外は、実施例１と同様にして実施例２〜８の記録媒体を得た。
【００３４】
比較例１
実施例１において、化合物具体例Ｎｏ．１の代わりに下記式（Ｖ）で示される化合物を用いたこと以外は、実施例１と同様にして比較例１の記録媒体を得た。
【化１０】

【００３５】
前記の実施例１〜８及び比較例１の記録媒体を用い、下記の記録条件で基板から光を入射して記録し、その後記録位置を再生光によりＣ／Ｎ及び反射率を測定した。その結果を表２に示す。
記録条件：
レーザ発振波長 ６８０ｎｍ
記録周波数 １．２５ＭＨｚ
記録線速 １．２ｍ／ｓｅｃ
再生条件：
レーザ発振波長 ６８０ｎｍ
再生パワー ０．２５〜０．３ｍＷの連続光
スキャニングバンド巾 ３０ＫＨｚ
耐光テスト条件：
耐光テスト ４万Ｌｕｘ、Ｘｅ光、５０時間連続照射
保存テスト ８５℃、８５％、７２０時間放置
【００３６】
【表２】

【００３７】
実施例９
深さ１０００Å、半値幅０．４５μｍ、トラックピッチ１．６μｍの案内溝を有する厚さ１．２ｍｍの射出成形ポリカーボネート基板上に、化合物具体例Ｎｏ．１をメチルシクロヘキサン、２−メトキシエタノール、メチルエチルケトン、テトラヒドロフランの混合溶液に溶解した液をスピンナー塗布し、厚さ１８００Åの記録層を形成し、次いでその上にスパッタ法によりＡｕ２０００Åの反射層を設け、更にその上にアクリル系フォトポリマーにて５μｍの保護層を設け、記録媒体を得た。
【００３８】
実施例１０〜１６
実施例９において、化合物具体例Ｎｏ．１の代わりにそれぞれ化合物具体例Ｎｏ．６、Ｎｏ．７、Ｎｏ．９、Ｎｏ．１１、Ｎｏ．１８、Ｎｏ．１９、Ｎｏ．２２を用いたこと以外は、実施例９と同様にして実施例１０〜１６の記録媒体を得た。
【００３９】
比較例２
実施例９において、化合物具体例Ｎｏ．１の代わりに比較例１で用いた前記式（Ｖ）で示される化合物を用いたこと以外は、実施例９と同様にして比較例２の記録媒体を得た。
【００４０】
実施例９〜１６及び比較例２の記録媒体に発振波長６８０ｎｍ、ビーム径１．４μｍの半導体レーザ光を用い、トラッキングしながらＥＦＭ信号を記録し（線速１．４ｍ／ｓｅｃ）、同じレーザの連続光で再生し、再生波形を観察した。その結果を表３に示す。
【００４１】
【表３】

【００４２】
実施例１７
深さ１０００Å、半値幅０．４５μｍ、トラックピッチ１．６μｍの案内溝を有する厚さ１．２ｍｍの射出成形ポリカーボネート基板上に、下記の式（ＶＩ）で示される化合物と化合物具体例Ｎｏ．２１とを、重量比（１／１）のメチルシクロヘキサン、２−メトキシエタノール、メチルエチルケトン、テトラヒドロフラン混合溶媒に溶解し、スピンナー塗布して、厚さ１７００Åの記録層を形成し、次いで、スパッタ法によりＡｕ２０００Åの反射層を形成して、更にその上にアクリル系フォトポリマーにて５μｍの保護層を設け、記録媒体を得た。
【００４３】
【化１１】

【００４４】
実施例１８及び１９
実施例１７において、化合物具体例Ｎｏ．２１の代わりにそれぞれ化合物具体例Ｎｏ．１８、Ｎｏ．１９を用いたこと以外は、実施例１７と同様にして実施例１８及び１９の記録媒体を得た。
【００４５】
実施例２０及び２１
実施例１７において、化合物具体例Ｎｏ．２１の代わりにそれぞれ化合物具体例Ｎｏ．２、Ｎｏ．２１を用い、且つ前記式（ＶＩ）で示される化合物の代わりに下記式（ＶＩＩ）で示される化合物を用いたこと以外は、実施例１７と同様にして実施例２０及び２１の記録媒体を得た。
【００４６】
【化１２】

【００４７】
実施例２２及び２３
実施例１７において、化合物具体例Ｎｏ．２１の代わりにそれぞれ化合物具体例Ｎｏ．１、Ｎｏ．２５を用い、且つ前記式（ＶＩ）で示される化合物の代わりに下記式（ＶＩＩＩ）で示される化合物を用いたこと以外は、実施例１７と同様にして実施例２２及び２３の記録媒体を得た。
【００４８】
【化１３】

【００４９】
比較例３〜５
実施例１７において、記録層をそれぞれ前記一般式（ＶＩ）で示される化合物のみ、前記一般式（ＶＩＩ）で示される化合物のみ、前記一般式（ＶＩＩＩ）で示される化合物のみとしたこと以外は、実施例１７と同様にして比較例３〜５の記録媒体を得た。
【００５０】
実施例１７〜２３及び比較例３〜５の記録媒体に発振波長７８０ｎｍ、ビーム径１．６μｍの半導体レーザ光を用い、トラッキングしながらＥＦＭ信号を記録し（線速１．４ｍ／ｓｅｃ）、前記レーザ及び発振波長６８０ｎｍ、ビーム径１．４μｍの半導体レーザの連続光で再生し、再生波形を観察した。その結果を表４に示す。
【００５１】
【表４】

【００５２】
【発明の効果】
請求項１の光記録媒体は、前記一般式（Ｉ）で示される化合物の少なくとも１種を記録層中に含有してなるものとしたことから、波長７００ｎｍ以下に高い光吸収能と光反射性を有しているため、高密度記録が可能な７００ｎｍ以下の波長域のレーザ光で記録、再生が可能であり、しかも耐光性、保存安定性に優れている。
【００５３】
請求項２の光記録体は、前記一般式（Ｉ）で示される化合物がｋ、ｌ、ｍ、ｎの各々が０、１又は２で且つその置換基の置換位置が１又は４であるものとしたことから、記録層の屈折率の向上が達成され、高反射率光記録媒体を得ることが可能となる。
【００５４】
請求項３の光記録媒体は、前記一般式（Ｉ）で示される化合物の少なくとも１種と６８０〜７５０ｎｍに最大吸収波長を有する有機色素とを記録層中に含有してなるものとしたことから、現状システムで記録、再生が可能で、しかも次世代の高密度光ディスクシステムでも、記録された情報を再生することが可能になる。
【００５５】
請求項４の光記録媒体は、６８０〜７５０ｎｍに最大吸収波長を有する有機色素として、ペンタメチンのシアニン色素、フタロシアニン色素及びアゾ金属キレート色素の少なくとも一種を選択したことから、高品位の信号特性が記録可能となる。
【図面の簡単な説明】
【図１】本発明の記録媒体に適用し得る通常の追記型光記録媒体としての層構成例を示す図である。
【図２】本発明の記録媒体に適用し得るＣＤ−Ｒ用としての層構成例を示す図である。
【符号の説明】
１ 基板
２ 記録層（有機色素層）
３ 下引き層
４ 保護層
５ ハードコート層
６ 反射層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a recording medium, and in particular, by irradiating a light beam, optical changes such as transmittance and reflectance of a recording material are caused, information is recorded and reproduced, and additional recording is performed. The present invention relates to a possible optical recording medium.
[0002]
[Prior art]
In the current write-once optical disc system (WORM, CD-R), the oscillation wavelength of the laser used is in the range of 770 nm to 790 nm, and the recording medium is configured to be able to record and reproduce at the above wavelength. In the future, it is essential to increase the capacity of recording media as the amount of information increases. Therefore, it is easily expected that the laser wavelength used for recording and reproduction will inevitably become shorter.
In addition, many proposals have been made to use a cyanine dye or a phthalocyanine dye as a recording material as a write-once optical disk for data (for example, those using a cyanine dye as a recording material are disclosed in JP-A-57-82093). JP, 58-56892, JP 58-12790, JP 58-114989, JP 59-85791, JP 60-83236, JP 60-89842, JP-A-61-25886, etc., and those using phthalocyanine dyes as recording materials include JP-A-61-150243, JP-A-61-177287, JP-A-61-154888, JP-A-61-246091, JP-A-62-39286, JP-A-63-37791, JP-A-63-39888, etc.) Excellent storage stability, and recorded in an optical pickup using the following laser 700 nm, the reproduction is possible recording materials, at present, not been developed yet.
[0003]
The current CD-R disc system is also configured to be able to record and reproduce at the oscillating wavelength of the laser used, 770 nm to 790 nm. In this system as well, it is essential to increase the capacity and shorten the recording / reproducing wavelength. In this regard, current CDs and CD-ROMs are coated with Al on the unevenness of the substrate itself, and the wavelength dependence of the reflectance of Al is small. Therefore, even if the laser wavelength is shortened in the future, reproduction will not be possible. Is possible.
However, CD-R uses a dye having a maximum absorption wavelength at 680 nm to 750 nm for the recording layer, and is set so as to obtain a high reflectance from 770 nm to 790 nm from its optical constant and film thickness configuration. Reflectance is extremely low in the wavelength range, and it is impossible to cope with the shortening of the laser wavelength, and information recorded and reproduced by the current CD-R system cannot be reproduced by a future system. Many proposals using a cyanine dye / metal reflective layer, a phthalocyanine dye / metal reflective layer or an azo metal chelate dye / metal reflective layer as a recording material have been made as CD-Rs (for example, cyanine dye / metal). In the case of using a reflective layer as a recording material, JP-A-1-159842, JP-A-2-42652, JP-A-2-13656, JP-A-2-168446, etc. use a phthalocyanine dye as a recording material. Those used are JP-A-1-176585, JP-A-3-215466, JP-A-4-113886, JP-A-4-226390, JP-A-5-1272, JP-A-5-171052, and JP-A-5-171052. JP-A-5-116456, JP-A-5-69860, JP-A-5-139044, and the like, and azo metal chelate dyes as recording materials Are disclosed in Japanese Patent Laid-Open No. 4-46186, Japanese Patent Laid-Open No. 4-14189, Japanese Patent Laid-Open No. 4-361888, Japanese Patent Laid-Open No. 5-279580, etc.). Nothing has been found yet.
[0004]
[Problems to be solved by the invention]
Accordingly, the present invention has been made in view of the above situation, and is light-resistant and storage applicable to a high-density optical disk system using a semiconductor laser having an oscillation wavelength shorter than that of the conventional system. Providing recording materials for optical recording media with excellent stability, as well as recording materials for CD-R media that can be recorded and reproduced with the current system and can be reproduced with the next-generation high-density optical disc system It is intended.
[0005]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that by providing a recording layer mainly composed of a dye having a specific structure, the present invention can be applied to a high-density optical disk system using a semiconductor laser having an oscillation wavelength of 700 nm or less. Furthermore, it has been found that by using this dye mixed with an organic dye currently used as a recording material for CD-R, it is possible to obtain a high reflectance even in a wavelength region of 700 nm or less. The invention has been completed.
[0006]
That is, according to the present invention, first,At least a recording layer is provided on the substrateAn optical recording medium is provided, wherein the recording layer contains at least one compound represented by the following general formula (I).
[Chemical 2]

[Wherein M, X¹~ X^Four, R¹~ R^Four, K, l, m, and n each represent the following.
M: two hydrogen atoms, a divalent, trivalent or tetravalent metal atom which may have an oxygen atom or a halogen atom, or (-OR^Five) O group, (-OSiR⁶R⁷R⁸) O group, (-OPOR⁹R^Ten) O group or (-OCOR¹¹) Metal atom having o group, R^Five~ R¹¹: Each independently a hydrogen atom, a substituted or unsubstituted monovalent aliphatic hydrocarbon group or a substituted or unsubstituted monovalent aromatic hydrocarbon group, o: an integer of 0 to 2, X¹~ X^Four: Each independently a hydrogen atom, a substituted or unsubstituted alkyl group, R¹~ R^Four: Each independently a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group, k, l, m, n: each independently an integer of 0-4, provided that k, l, m, n are simultaneously 0 Never become. In addition, when k, l, m, and n are 3 or less, the other substituent of a benzene ring is a hydrogen atom or a halogen atom. )
Second, in the optical recording medium described in the first, the compound represented by the general formula (I) is such that each of k, l, m and n is independently an integer of 0 to 2, and the substitution thereof. An optical recording medium in which the substitution position of the group is 1 or 4 is provided. Third, in the optical recording medium described in the first or second, the recording layer comprises at least one compound represented by the general formula (I) and an organic dye having a maximum absorption wavelength at 680 nm to 750 nm. An optical recording medium characterized by being contained is provided. Fourthly, in the optical recording medium described in the third aspect, an optical recording medium in which the organic dye having the maximum absorption wavelength at 680 nm to 750 nm is at least one of pentamethine cyanine dye, phthalocyanine dye and azo metal chelate dye. Provided.In the optical recording medium of the present invention, a reflective layer made of aluminum or gold and a protective layer made of an ultraviolet curable resin can be provided on the recording layer as necessary.
[0007]
Since the optical recording medium of the present invention is provided with a recording layer containing at least one compound represented by the general formula (I), it can be recorded and reproduced with a laser beam having a wavelength region of 700 nm or less. In another embodiment, it is a mixture of at least one compound represented by the general formula (I) and an organic dye having a maximum absorption wavelength at 680 to 750 nm. Since the recording layer is provided, it can be used as a CD-R medium in the current system, and the described information can be reproduced even in a next-generation high-density optical disc system.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
The optical recording medium of the present invention is characterized in that the recording layer contains at least one compound represented by the general formula (I).
First, the compound represented by the general formula (I) used in the present invention will be described. In the general formula (I), M may have two hydrogen atoms, oxygen atoms or halogen atoms 2 Valent, trivalent or tetravalent metal atom, or (-OR⁵) O group, (-OSiR⁶R⁷R⁸) O group, (-OPOR⁹R¹⁰) O group or (-OCOR¹¹) Represents a metal atom having an o group.
Where R⁵~ R¹¹Each independently represents a hydrogen atom, a substituted or unsubstituted monovalent aliphatic hydrocarbon group or a substituted or unsubstituted monovalent aromatic hydrocarbon group, and o represents an integer of 0 to 2. X¹~ X⁴Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, and R¹~ R⁴Each independently represents a hydrogen atom, a substituted or unsubstituted linear or branched alkyl group. Moreover, k, l, m, and n each independently represent an integer of 0 to 4, and k, l, m, and n are not 0 simultaneously. In addition, when k, l, m, and n are 3 or less, the other substituent of a benzene ring is a hydrogen atom or a halogen atom.
[0009]
In particular, [CX in general formula (I)¹(COOR¹)₂The so-called α-substituted product in which the number of substituents represented by k and the like is 1 or 2 and the substitution position is 1 or 4 is advantageous when adjusting the absorption wavelength, and inhibits association when the film thickness is reduced. Therefore, it is possible to achieve a high refractive index of the thin film, and a high reflectivity when used as a recording medium.
[0010]
In the general formula (I), particularly when k = 1 = m = 1, the following four isomers (A) to (D) exist, and the absorption band of the recording film is slightly expanded. This often contributes to widening the recording wavelength margin and recording power margin.
[Chemical 2]

[Chemical 3]

[Formula 4]

[Chemical formula 5]

Y in the above formula¹~ Y⁴[CX¹(COOR¹)₂] K to [CX⁴(COOR⁴)₂] Represents n.
[0011]
In general formula (I), X¹~ X⁴Specific examples of the alkyl group include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, isobutyl group, n-pentyl group, neopentyl group, isoamyl group, n-hexyl group, and n-octyl group. Primary alkyl groups such as n-nonyl group, n-decyl group and n-dodecyl group; secondary alkyl groups such as isopropyl group and sec-butyl group. These alkyl groups may be substituted at a specific position with a halogen atom or the like.
[0012]
In general formula (I), R¹~ R⁴Specific examples of the alkyl group include, for example, methyl group, ethyl group, n-propyl group, n-butyl group, isobutyl group, n-pentyl group, neopentyl group, isoamyl group, n-hexyl group, and n-octyl group. , N-nonyl group, n-decyl group, n-dodecyl group and the like primary alkyl group; isopropyl group, sec-butyl group and the like secondary alkyl group; tert-butyl group, tert-hexyl group, tert-amyl group, A tertiary alkyl group such as a tert-octyl group can be mentioned. These alkyl groups may be substituted at a specific position with a halogen atom or the like.
[0013]
In the general formula (I), specific examples of M include hydrogen atoms; divalent metals such as Ca, Mg, Zu, Cu, Ni, Pd, Fe, Pb, Co, Pt, Cd, and Ru; Al, In , Fe, Ga, Tl, Mn, etc. Trivalent metal halides, hydroxylates, alkoxylates, trialkylsiloxides, etc .; and Si, Ti, Sn, Cr, Ga, Sn, Mn, Zr, V, etc. Examples thereof include halides, hydroxylates, alkoxylates, trialkylsiloxylates and oxides of valent metals. The R⁵~ R¹¹In the definition, the monovalent aliphatic hydrocarbon group includes methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, amyl group, hexyl group, octyl group. And alkyl groups such as a group, decyl group, dodecyl group and octadecyl group, and alkenyl groups such as a vinyl group, an allyl group, an isopropenyl group, a 1-butenyl group, a 2-butenyl group and a 2-pentenyl group. Examples of the monovalent aromatic hydrocarbon group include a phenyl group and a benzyl group. Examples of the substituent include halogen atoms such as fluorine, chlorine and bromine, a carbon trifluoride group, a cyano group, and an ester group.
[0014]
Specific examples of the compound represented by the general formula (I) include those shown in Tables 1- (1) to 1- (2).
[0015]
[Table 1- (1)]

[0016]
[Table 1- (2)]

[0017]
In the recording layer, as described above, the main component is a mixture of at least one compound represented by the general formula (I) and an organic dye having a maximum absorption wavelength at 680 to 750 nm. It is a CD-R recording medium that can be recorded and reproduced by the current system and can only be reproduced by the next generation system. As the dye having the maximum absorption wavelength at 680 to 750 nm in this case, a pentamethine cyanine dye, a phthalocyanine dye and an azo metal chelate dye are preferable.
[0018]
Preferable examples of the cyanine dye of pentamethine include those represented by the following general formula (II).
[Chemical 6]

Where R²¹, R²²Is an alkyl group having 1 to 3 carbon atoms, R²³, R²⁴Represents a substituted or unsubstituted alkyl group having 1 to 6 carbon atoms, and X represents an acid anion. The aromatic ring may be condensed with another aromatic ring, and may be substituted with an alkyl group, a halogen atom, an alkoxy group, or an acyl group.
[0019]
Preferable examples of the phthalocyanine dye include those represented by the following general formula (III-1) or (III-2).
[Chemical 7]

Where M¹Represents Ni, Pd, Cu, Zn, Co, Mn, Fe, TiO or VO, X⁵~ X⁸Each independently represents —OR or —SR at the substituted position α, R represents an optionally substituted linear, branched or alicyclic alkyl group having 3 to 12 carbon atoms or an optionally substituted aryl group. Represents. X⁵~ X⁸The substituent on the benzene ring other than is a hydrogen atom or a halogen atom.
[0020]
[Chemical 8]

Where M²Is Si, Ge, In, or Sn, X⁹~ X¹²Each independently represents —OR or —SR at the substituted position α, R represents an optionally substituted linear, branched or alicyclic alkyl group having 3 to 12 carbon atoms or an optionally substituted aryl group. Y⁵, Y⁶Is -OSiR²⁵R²⁶R²⁷, -OCOR²⁵R²⁶R²⁷Or -OPOR²⁵R²⁶R²⁷Represents R²⁵~ R²⁷Each independently represents an alkyl or aryl group having 1 to 10 carbon atoms. X⁹~ X¹²The substituent of the benzene ring other than is a hydrogen atom or a halogen atom.
[0021]
Moreover, as a preferable example of an azo metal chelate pigment | dye, the 1 type, or 2 or more types of the azo metal chelate compound of the azo type compound and metal shown by the following general formula (IV) are mentioned, As a preferable example of a metal, , Ni, Pt, Pd, Co, Cu, Zn and the like.
[Chemical 9]

Wherein A represents a residue that forms a heterocycle with the carbon and nitrogen atoms to which it is attached, and B represents an aromatic ring with the two carbon atoms to which it is attached. Alternatively, it represents a residue that forms a heterocyclic ring, and X represents a group having an active hydrogen.
[0022]
The weight composition ratio of the present invention when the at least one dye represented by the general formula (I) and at least one dye represented by the general formulas (II) to (IV) are used in combination is as follows. / [Dye of (II) to (IV)] = 10/100 to 90/100, preferably 40/100 to 20/100. Further, when both dyes are used in combination, the thickness of the recording layer is 500 to 5 μm, preferably 1000 to 5000 mm.
[0023]
Next, the configuration of the recording medium of the present invention will be described.
FIG. 1 is a diagram showing an example of a layer structure applicable to the recording medium of the present invention, which is an example of a write-once type optical disc. A recording layer 2 is provided on the substrate 1 via an undercoat layer 3 as necessary, and a protective layer 4 is further provided as necessary. Further, a hard coat layer can be provided under the substrate 1 as necessary.
FIG. 2 is a diagram showing another example of a layer structure applicable to the recording medium of the present invention, which is an example of CD-R media. A reflective layer 6 is provided on the recording layer 2 having the configuration shown in FIG.
The recording medium of the present invention may have an air sandwich structure in which the recording layer (organic thin film layer) having the configuration shown in FIGS. 1 and 2 is placed inside and sealed with another substrate through a space. A laminated structure bonded via a protective layer may be used.
[0024]
Next, the required characteristics of the constituent layers and the constituent materials will be described.
1) Substrate
As a necessary characteristic of the substrate, when recording / reproducing is performed from the substrate side, it must be transparent to the laser beam used. However, when recording / reproducing is performed from the recording layer side, it is not necessary to be transparent. As the substrate material, for example, polyester, acrylic resin, polyamide, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, polyimide or other plastic, glass, ceramic, metal, or the like can be used. A tracking guide groove or guide pit and a preformat such as an address signal may be formed on the surface of the substrate.
[0025]
2) Recording layer
The recording layer is capable of recording information by the optical change caused by laser light irradiation. In the recording layer, at least one of the compounds represented by the general formula (I) may be included. Furthermore, it is necessary to contain at least one dye represented by the general formulas (II) to (IV). Furthermore, these dyes can of course be mixed or laminated with other organic dyes, metals, and metal compounds in order to improve optical characteristics, recording sensitivity, and signal characteristics. Other organic dyes in this case include polymethine dyes, naphthalocyanine, phthalocyanine, squarylium, croconium, pyrylium, naphthoquinone, anthraquinone (indanthrene), xanthene, triphenylmethane, and azulene , Tetrahydrocholine-based, phenanthrene-based, triphenothiazine-based dyes, metal complex compounds, and the like. Examples of metals and metal compounds include In, Te, Bi, Se, Sb, Ge, Sn, Al, Be, TeO.₂, SnO, As, Cd, etc., each of which can be used in the form of dispersion mixing or lamination. In addition, various materials such as ionomer resins, polyamide resins, vinyl resins, natural polymers, silicones, liquid rubbers, or silane coupling agents may be dispersed and mixed in the dyes. For the purpose of improvement, it can be used together 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 using the coating method, the above-mentioned dye or the like can be dissolved in an organic solvent, and a conventional coating method such as spraying, roller coating, dipping or spin coating can be used. As the organic solvent used, alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone and cyclohexanone, amides such as N, N-dimethylacetamide and N, N-dimethylformamide, and sulfoxides such as dimethyl sulfoxide are generally used. Ethers such as tetrahydrofuran, dioxane, diethyl ether and ethylene glycol monomethyl ether, esters such as methyl acetate and ethyl acetate, aliphatic halogenated carbons such as chloroform, methylene chloride, dichloroethane, carbon tetrachloride and trichloroethane, benzene , Aromatics such as xylene, monochlorobenzene and dichlorobenzene, or cellsolves such as methoxyethanol and ethoxyethanol, hexane, Tan, cyclohexane, and hydrocarbons such as methylcyclohexane.
The film thickness of the recording layer is 100 to 10 μm, preferably 200 to 2000 μm.
[0027]
3) Undercoat layer
The undercoat layer is: (1) improved adhesion, (2) barrier against water or gas, (3) improved storage stability of recording layer, (4) improved reflectivity, (5) substrate from solvent And (6) guide grooves, guide pits, preformats, etc. For the purpose of (1), polymer materials such as ionomer resins, polyamides, vinyl resins, natural resins, natural polymers, silicones, liquid rubbers, various polymer compounds and silane coupling agents are used. For the purposes of (2) and (3), in addition to the above polymer materials, inorganic compounds such as SiO₂, MgF₂, SiO, TiO₂, ZnO, TiN, SiN, and the like, and metal or semimetal such as Zn, Cu, Ni, Cr, Ge, Se, Au, Ag, and Al can be used. For the purpose of (4), metals such as Al, Au and Ag, and organic thin films having metallic luster such as methine dyes and xanthene dyes can be used. (5) and (6) For the purpose of ▼, 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.
[0029]
5)Substrate surface hard coat layer
Substrate surface hard coat layer, (I) protect the recording layer (reflection / absorption layer) from scratches, dust, dirt, etc., (ii) improve the storage stability of the recording layer (reflection / absorption layer), and (iii) improve the reflectivity used. For these purposes, the materials shown for the undercoat layer can be used. Also, inorganic materials such as SiO and SiO₂Can also be used, such as polymethyl acrylate, polycarbonate, epoxy resin, polystyrene, polyester resin, vinyl resin, cellulose, aliphatic hydrocarbon resin, natural rubber, styrene-butadiene resin, chloroprene rubber, wax, alkyd resin Also, heat softening and heat melting resins such as drying oil and rosin can be used. The most preferable among the above materials is an ultraviolet curable resin excellent in productivity.Substrate surface hard coat layerThe film thickness is 0.01-30 μm, preferably 0.05-10 μm.
[0030]
In the present invention, the undercoat layer, the protective layer, and the substrate surface hard coat layer, as in the recording layer, include a stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, a plasticizer, and the like. Can be contained.
[0031]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.
[0032]
Example 1
Example 1
On a substrate in which a guide groove having a depth of 1200 mm, a half width of 0.4 μm, and a track pitch of 1.4 μm is formed by a photopolymer on a polymethyl methacrylate substrate having a thickness of 1.2 μm, the compound specific example No. The 1,2-dichloroethane solution of No. 1 was spinner coated to provide a recording layer having a thickness of 800 mm to obtain a recording medium.
[0033]
Examples 2-8
In Example 1, compound specific examples No. In place of compound No. 1 2, no. 4, no. 6, no. 7, no. 9, no. 14, no. Recording media of Examples 2 to 8 were obtained in the same manner as Example 1 except that 21 was used.
[0034]
Comparative Example 1
In Example 1, compound specific examples No. A recording medium of Comparative Example 1 was obtained in the same manner as in Example 1 except that a compound represented by the following formula (V) was used instead of 1.
[Chemical Formula 10]

[0035]
Using the recording media of Examples 1 to 8 and Comparative Example 1 described above, light was incident from the substrate under the following recording conditions for recording, and then the C / N and reflectance were measured at the recording position with reproduction light. The results are shown in Table 2.
Recording conditions:
Laser oscillation wavelength 680nm
Recording frequency 1.25MHz
Recording linear velocity 1.2m / sec
Playback conditions:
Laser oscillation wavelength 680nm
Continuous light with reproduction power of 0.25-0.3mW
Scanning band width 30KHz
Light resistance test conditions:
Light resistance test 40,000 Lux, Xe light, 50 hours continuous irradiation
Storage test 85 ° C, 85%, left for 720 hours
[0036]
[Table 2]

[0037]
Example 9
On a 1.2 mm-thick injection-molded polycarbonate substrate having a guide groove with a depth of 1000 mm, a half width of 0.45 μm, and a track pitch of 1.6 μm, the compound specific example No. A solution prepared by dissolving 1 in a mixed solution of methylcyclohexane, 2-methoxyethanol, methyl ethyl ketone, and tetrahydrofuran was applied by a spinner to form a recording layer having a thickness of 1800 mm, and then a reflective layer of Au2000 mm was formed thereon by a sputtering method. A protective layer of 5 μm was provided thereon with an acrylic photopolymer to obtain a recording medium.
[0038]
Examples 10-16
In Example 9, compound specific examples No. In place of Compound No. 1, Compound Specific Example No. 6, no. 7, no. 9, no. 11, no. 18, no. 19, no. Recording media of Examples 10 to 16 were obtained in the same manner as Example 9 except that 22 was used.
[0039]
Comparative Example 2
In Example 9, compound specific examples No. A recording medium of Comparative Example 2 was obtained in the same manner as Example 9 except that the compound represented by the formula (V) used in Comparative Example 1 was used instead of 1.
[0040]
A semiconductor laser beam having an oscillation wavelength of 680 nm and a beam diameter of 1.4 μm was used for the recording media of Examples 9 to 16 and Comparative Example 2, and an EFM signal was recorded while tracking (linear velocity: 1.4 m / sec). Reproduction was performed with continuous light, and the reproduction waveform was observed. The results are shown in Table 3.
[0041]
[Table 3]

[0042]
Example 17
A compound represented by the following formula (VI) and compound specific example No. 1 were formed on an injection-molded polycarbonate substrate having a depth of 1000 mm, a half width of 0.45 μm, and a track groove having a guide pitch of 1.6 μm and a thickness of 1.2 mm. 21 is dissolved in a mixed solvent of methylcyclohexane, 2-methoxyethanol, methyl ethyl ketone, and tetrahydrofuran in a weight ratio (1/1), and spinner coating is performed to form a recording layer having a thickness of 1700 mm. Was formed, and a protective layer of 5 μm was further formed thereon with an acrylic photopolymer to obtain a recording medium.
[0043]
Embedded image

[0044]
Examples 18 and 19
In Example 17, the compound specific examples No. In place of compound No. 21, compound specific examples No. 18, no. Recording media of Examples 18 and 19 were obtained in the same manner as Example 17 except that 19 was used.
[0045]
Examples 20 and 21
In Example 17, the compound specific examples No. In place of compound No. 21, compound specific examples No. 2, no. Recording media of Examples 20 and 21 were obtained in the same manner as in Example 17 except that 21 was used and a compound represented by the following formula (VII) was used instead of the compound represented by the above formula (VI). It was.
[0046]
Embedded image

[0047]
Examples 22 and 23
In Example 17, the compound specific examples No. In place of compound No. 21, compound specific examples No. 1, no. 25, and the recording media of Examples 22 and 23 were obtained in the same manner as in Example 17 except that the compound represented by the following formula (VIII) was used instead of the compound represented by the above formula (VI). It was.
[0048]
Embedded image

[0049]
Comparative Examples 3-5
In Example 17, except that the recording layer was only the compound represented by the general formula (VI), only the compound represented by the general formula (VII), and only the compound represented by the general formula (VIII). In the same manner as in Example 17, the recording media of Comparative Examples 3 to 5 were obtained.
[0050]
A semiconductor laser beam having an oscillation wavelength of 780 nm and a beam diameter of 1.6 μm was used for the recording media of Examples 17 to 23 and Comparative Examples 3 to 5, and an EFM signal was recorded while tracking (linear velocity 1.4 m / sec). The reproduction waveform was observed by reproducing with continuous light of a laser and a semiconductor laser having an oscillation wavelength of 680 nm and a beam diameter of 1.4 μm. The results are shown in Table 4.
[0051]
[Table 4]

[0052]
【The invention's effect】
Since the optical recording medium according to claim 1 contains at least one of the compounds represented by the general formula (I) in the recording layer, it has a high light absorption ability and light reflectivity at a wavelength of 700 nm or less. Therefore, recording and reproduction can be performed with a laser beam having a wavelength range of 700 nm or less that enables high-density recording, and light resistance and storage stability are excellent.
[0053]
The optical recording medium according to claim 2, wherein the compound represented by the general formula (I) is such that k, l, m, n are each 0, 1, or 2 and the substitution position of the substituent is 1 or 4. Therefore, the refractive index of the recording layer can be improved, and a high reflectance optical recording medium can be obtained.
[0054]
The optical recording medium according to claim 3 contains at least one compound represented by the general formula (I) and an organic dye having a maximum absorption wavelength at 680 to 750 nm in the recording layer. Recording and reproduction can be performed with the current system, and recorded information can be reproduced with the next-generation high-density optical disc system.
[0055]
In the optical recording medium according to claim 4, since at least one of pentamethine cyanine dye, phthalocyanine dye and azo metal chelate dye is selected as the organic dye having the maximum absorption wavelength at 680 to 750 nm, high quality signal characteristics are recorded. It becomes possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a layer structure as a normal write-once type optical recording medium that can be applied to the recording medium of the present invention.
FIG. 2 is a diagram showing an example of a layer structure for CD-R that can be applied to the recording medium of the present invention.
[Explanation of symbols]
1 Substrate
2 Recording layer (organic dye layer)
3 Underlayer
4 Protective layer
5 Hard coat layer
6 Reflective layer

Claims (4)

An optical recording medium comprising at least a recording layer on a substrate , wherein the recording layer contains at least one compound represented by the following general formula (I).

[Wherein, M, X ^{1 to} X ⁴ , R ^{1 to} R ⁴ , k, l, m and n each represent the following.
M: two hydrogen atoms, or a divalent, trivalent or tetravalent metal atom which may have an oxygen atom or a halogen atom, or a (—OR ⁵ ) o group, (—OSiR ⁶ R ⁷ R ⁸ ) o group, (—OPOR ⁹ R ¹⁰ ) o group or (—OCOR ¹¹ ) o group-containing metal atom, R ^{5 to} R ¹¹ : each independently a hydrogen atom, a substituted or unsubstituted monovalent aliphatic hydrocarbon group Or a substituted or unsubstituted monovalent aromatic hydrocarbon group, o: an integer of 0 to 2, X ^{1 to} X ⁴ : each independently a hydrogen atom, a substituted or unsubstituted alkyl group, R ^{1 to} R ⁴ : each Independently hydrogen atom, substituted or unsubstituted linear or branched alkyl group, k, l, m, n: each independently an integer of 0 to 4, provided that k, l, m, n are simultaneously 0 There is no. In addition, when k, l, m, and n are 3 or less, the other substituent of the benzene ring is a hydrogen atom or a halogen atom. ] 2. The compound represented by the general formula (I), wherein each of k, l, m and n is independently an integer of 0 to 2, and the substitution position of the substituent is 1 or 4. Optical recording media. 3. The light according to claim 1, wherein the recording layer contains at least one compound represented by the general formula (I) and an organic dye having a maximum absorption wavelength at 680 nm to 750 nm. recoding media. 4. The optical recording medium according to claim 3, wherein the organic dye having a maximum absorption wavelength at 680 nm to 750 nm is at least one of a pentamethine cyanine dye, a phthalocyanine dye, and an azo metal chelate dye.

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