JP3742492B2 - Optical recording medium and optical recording / reproducing method using the optical recording medium - Google Patents

Description

【０００８】
〔式中、Ｍは、２価、３価もしくは４価の金属原子であって、酸素原子、ハロゲン原子、（ＯＳｉＲ_１５Ｒ_１６Ｒ_１７）ｔの何れかを有していても良く、Ｒ_１５〜Ｒ_１７はそれぞれ独立して置換基を有していても良い脂肪族炭化水素基を表わす。ｔは２を表わす。Ｒ_１〜Ｒ_４はそれぞれ独立して少なくともフッ素原子、フッ素含有アルキル基（以下、フッ素含有置換基とも言う。）で置換されたフェニル基（以下、フッ素含有フェニル基とも言う。）である。また、Ｘ_１〜Ｘ_４は水素原子またはハロゲン原子である。〕
【０００９】
前式（１）の化合物において、Ｘ₁〜Ｘ₄の全てをハロゲンとすることで、分解点の低下が画れて記録感度の向上が見込まれる。ハロゲンとして、臭素および塩素が特に好ましい。
【００１０】
また、前式（１）のＲ_１〜Ｒ_４のフェニル基の置換基であるフッ素置換アルキル基としては、例えば、トリフルオルメチル基、トリフルオロエチル基、ジフルオロエチル基、ジフルオロプロピル基、トリフルオロプロピル基、テトラフルオロプロピル基、ヘキサフルオロブチル基、または各種ペリフルオロアルキル基などが挙げられる。
またＲ_１〜Ｒ_４のフッ素含有フェニル基は、前記フッ素置換アルキル以外の基で置換されていても良く、その具体的な置換基としては、アルキル基、アルコキシ基、ニトロ基、シアノ基、ハロゲンなどが挙げらるが、この中でもハロゲンが最も好ましく、該ハロゲンとしては塩素、臭素が好ましい。
その理由としては分解点の低下に寄与し、光記録媒体の高感度化が図れるためである。
【００１１】
前式（１）の化合物には下式（Ａ）〜（Ｄ）の４つの異性体が存在し、これらの混合物である場合、吸収波長等の特性を微調整する際、これら異性体の量を変えることにより微調整が可能となり、かつ薄膜化した時の記録パワーマージン等の拡大を行うことができる。
【００１２】
【化３】

以下に本発明で使用される化合物の具体例を示す。ただし、本発明で使用する化合物はこれらに限定されるものではないし、これら化合物には前記（Ａ）〜（Ｄ）に示すような４つの異性体が存在する。なお、表１〜表７に示した化合物のうち、請求項１〜３で規定する化合物群に含まれないものは参考例である。
【００１３】
【化４】

【表１】

【００１４】
【表２】

【００１５】
【表３】

【００１６】
【表４】

【００１７】
【表５】

【００１８】
【表６】

【００１９】
【表７】

【００２０】
本発明において、６８０ｎｍ〜７５０ｎｍ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短波長対応ＣＤ−Ｒ媒体を構成する場合、前記従来技術に挙げた公報に記載の色素をそのまま使用することができるが、特に６８０ｎｍ〜７５０ｎｍに吸収最大波長のある色素の好ましい例としては、以下のようなものが挙げられる。
【００２１】
▲１▼下式（２）で示されるシアニン色素
【化５】

（式中、Ｒ₅、Ｒ₆：炭素数１〜３のアルキル基。
Ｒ₇、Ｒ₈：炭素数１〜６の置換基を有していても良いアルキル基。
Ｘ：酸アニオン。
なお、芳香環は他の芳香環と縮合されていても良く、またアルキル、
ハロゲン、アルコキシ基、アシル基で置換されていても良い。）
【００２２】
▲２▼下式（３）または（４）で示されるフタロシアニン色素
【化６】

（式中、Ｍ₁：Ｎｉ、Ｐｄ、Ｃｕ、Ｚｎ、Ｃｏ、Ｍｎ、Ｆｅ、ＴｉＯ、ＶＯ。
Ｘ₅〜Ｘ₈：α位の−ＯＲ、−ＳＲ、又は水素原子であって、全てが水素原子となることはない。
Ｒ：置換基を有していても良い炭素数３〜１２の直鎖アルキル基あるいは置換基を有していても良い分岐のアルキル基、置換基を有していても良いシクロアルキル基、又は置換基を有していても良いアリール基。
ベンゼン環は、前記Ｘ₅〜Ｘ₈以外に置換基を有していても良く、その場合のベンゼン環の置換基は水素又はハロゲン。）
【００２３】
【化７】

（式中、Ｍ₂：Ｓｉ、Ｇｅ、Ｉｎ、Ｓｎ。
Ｘ₉〜Ｘ₁₂：α位の−ＯＲ、−ＳＲ、又は水素原子であって、全てが水素原子となることはない。
Ｒは前記に同じ。
Ｙ₃、Ｙ₄：−ＯＳｉＲａＲｂＲｃ、−ＯＣＯＲａ、−ＯＰＯＲａＲｂ。
Ｒａ、Ｒｂ、Ｒｃ：炭素数１〜１０のアルキル基、アリール基。
ベンゼン環は前記Ｘ₉〜Ｘ₁₂以外に置換基を有していても良く、その場合のベンゼン環の置換基は水素又はハロゲンである。）
▲３▼アゾ金属キレート化合物
下式（５）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種以上であり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。
【００２４】
【化８】

（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２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す。Ｘは活性水素を有する基を表わす。）
【００２５】
前記本発明の色素と上記具体例を含む６８０ｎｍ〜７５０ｎｍに吸収最大波長を有する色素との混合比は、本発明の色素／６８０ｎｍ〜７５０ｎｍに吸収を有する色素＝１０／１００〜９０／１００、好ましくは４０／１００〜２０／１００である。記録層の厚みとしては５００Å〜５μｍ、好ましくは１０００Å〜５０００Åである。
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図１（この構造のものとしては、図１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良いし、密着貼り合わせ構造としても良い）と図２からなるＣＤ−Ｒ用メディアの構造としても良いし、これを接着剤で２枚貼り合わせた構造としても良い。さらに図３に示したＤＶＤ−Ｒ用の層構成としても良いし、これを２枚貼り合わせた構造としても良い。
【００２６】
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ー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又は、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。尚、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良い。
【００２７】
記録層
記録層は、レーザー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色素が含有されていることが必要で、記録層の形成に当たって本発明の色素１種、又は２種以上の組み合わせで用いても良い。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及び金属、金属化合物と混合又は積層化して用いても良い。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、アントラキノン系（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。
【００２８】
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。
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、可塑剤などを一緒に用いることが出来る。
【００２９】
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、ディピング及び、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うことが出来る。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。
【００３０】
下引き層
下引き層は▲１▼接着性の向上、▲２▼水又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、ＭｇＦ、ＳｉＯ₂、ＴｉＯ、ＺｎＯ、ＴｉＮ、ＳｉＮなどがあり、さら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。又、▲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。
【００３１】
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良く、２種の合金としても良い。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。
【００３２】
保護層、基板面ハードコート層
保護層及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。又、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。保護層又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、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、可塑剤等を含有させることができる。
【００３３】
保護基板
保護基板はこの保護基板側からレーザー光を照射する場合、使用レーザー光に対し透明でなくてはならず、単なる保護板として用いる場合、透明性は問わない。使用可能な基板材料としては基板材料と全く同様であり、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又は、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。
【００３４】
接着剤
２枚の記録媒体を接着できる材料なら何でもよく、生産性を考えると、紫外線硬化型もしくはホットメルト型接着剤が好ましい。
【００３５】
【実施例】
以下、本発明の実施例を示す。但し、本発明はこれら実施例に限定されるものではない。
【００３６】
実施例１
厚さ、１．２ｍｍのＰＭＭＡ基板上に、フォトポリマーにて深さ１２００Å、半値幅０．３５μｍ、トラックピッチ１．０μｍの案内溝を形成した基板上に、化合物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９００Åの記録層を形成し、記録媒体とした。
【００３７】
実施例２〜８
実施例１で化合物Ｎｏ．１の代わりにＮｏ．２、９、１２、１３、１９、２６、２９を用い実施例１と全く同様に記録媒体を形成した。
【００３８】
比較例１
実施例１で化合物例Ｎｏ．１の代わりに、以下に示す化合物を用いた以外は実施例１と全く同様にして記録媒体を形成した。
【化９】

【００３９】
前記実施例１〜８および比較例１の記録媒体を下記の条件で評価試験を行ない、その結果を下記表８に示した。
〈記録条件〉
レーザー発振波長：６５０ｎｍ
記録周波数：１．２５ＭＨｚ
記録線速：１．２ｍ／ｓｅｃ
〈再生条件〉
レーザー発振波長：６５０ｎｍ
再パワー：０．２５〜０．３ｍＷの連続光
スキャニングバンド幅：３０ＫＨｚ
〈耐光テスト条件〉
耐光テスト：４万Ｌｕｘ、Ｘｅ光、２０時間連続照射
保存テスト：８５℃ ８５％ ７２０時間放置
【００４０】
【表８】

【００４１】
実施例９
深さ１０００Å、半値幅０．３５μｍ、トラックピッチ１．０μｍ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．２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５μｍの保護層を設け、さらにその上にホットメルト接着剤により厚み０．６ｍｍのポリカーボネート基板を貼り合わせて記録媒体とした。
【００４２】
実施例１０〜１６
実施例９で化合物Ｎｏ．２の代わりにそれぞれ、化合物Ｎｏ．４、８、９、１５、１７、２２、２４を用い、実施例９と全く同様に記録媒体を得た。
【００４３】
比較例２
実施例９で有機薄膜として、化合物Ｎｏ．２の代わりに比較例１の前式（６）の化合物を用いて記録媒体とした。
【００４４】
比較例３
実施例９で有機薄膜として、化合物Ｎｏ．２の代わりに下式（７）の化合物を用いて記録媒体とした。
【化１０】

【００４５】
前記実施例９〜１６および比較例２〜３の記録媒体に発振波長６３５ｎｍ、ビーム径１．０μｍの半導体レーザー光を用い、トラッキングしながらＥＦＭ信号を記録（線速１．４ｍ／ｓｅｃ）し、同じレーザーの連続光で再生し、再生波形を観察しその結果を下表９に示す。
【００４６】
【表９】

【００４７】
実施例１７
深さ１０００Å、半値幅０．４０μｍ、トラックピッチ１．１μｍ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、前式（７）化合物と化合物Ｎｏ．５とを重量比１：１で混合し、これ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混合溶媒に溶解、スピンナー塗布して、厚さ１６００Åの有機色素層を形成し、次いで、スパッタ法により金２１００Åの反射層を形成して、さらにその上にアクリル系フォトポリマーで７μｍの保護層を設け、記録媒体とした。
【００４８】
実施例１８〜１９
実施例１７で記録層を化合物Ｎｏ．５の代わりに、それぞれ、Ｎｏ．１０、２０を用い実施例１７と全く同様に記録媒体を得た。
【００４９】
実施例２０〜２１
実施例１７で記録層を化合物Ｎｏ．５の代わりに、それぞれ、Ｎｏ．８、２４を用い前式（７）の化合物の代わりに下式（８）の化合物を用いた以外は実施例１７と全く同様に記録媒体を得た。
【化１１】

〔式中、Ｘは下式（９）の基を表わす。〕
【化１２】

【００５０】
実施例２２〜２３
実施例１７で記録層を化合物Ｎｏ．５の代わりに、それぞれ、Ｎｏ．１１、１４を用い、前式（７）の化合物の代わりに下式（１０）の化合物を用いた以外は実施例１７と全く同様に記録媒体を得た。
【化１３】

【００５１】
比較例４〜６
実施例１７で有機記録層をそれぞれ前式（７）の化合物のみ、前式（８）の化合物のみ、前式（１０）の化合物のみとして、実施例１７と同様に記録媒体を得た。
【００５２】
前記実施例１７〜２３および比較例４〜６の記録媒体に発振波長７８０ｎｍ、ビーム径１．６μｍの半導体レーザーを用い、トラッキングしながらＥＦＭ信号を記録（線速１．４ｍ／ｓｅｃ）し、前記レーザー及び、発振波長６３５ｎｍ、ビーム径１．１μｍの半導体レーザーの連続光で再生し、再生波形を観察しその結果を下表１０に示す。
【００５３】
【表１０】

【００５４】
【効果】
１．請求項１〜４
（１）７００ｎｍ以下の波長域のレーザー光で記録、再生が可能で耐光性、保存安定性に優れた情報記録媒体が提供できた。
（２）現状システムでのＣＤ−Ｒとして使用でき、かつ次世代の高密度光ディスクシステムとなっても、記録された情報を再生可能な情報記録媒体が提供できた。
２．請求項５
短波長の記録光で記録および／または再生が可能な記録および／または再生法が提供された。
【図面の簡単な説明】
【図１】通常の追記型光記録媒体の構成の模式的断面図である。
（ａ）基板１上に記録層２を有する型のものを示す図である。
（ｂ）前記（ａ）の基板１上に下引き層３を有する型のものを示す図である。
（ｃ）前記（ｂ）の記録層２上に保護層４を有する型のものを示す図である。
（ｄ）前記（ｃ）の基板１裏面にハードコート層５を有する型のものを示す図である。
【図２】ＣＤ−Ｒ用の媒体構成の模式的断面図である。
（ａ）基板１上に記録層２、金属反射層６および保護層４を有する型のものを示す図である。
（ｂ）前記（ａ）の基板１上に下引き層３を有する型のものを示す図である。
（ｃ）前記（ｂ）の基板１裏面にハードコート層５を有する型のものを示す図である。
【図３】ＣＶＤ−Ｒ用の媒体構成の模式的断面図である。
（ａ）基板１上に記録層２、金属反射層６および保護層４を有する型のものを示す図である。
（ｂ）前記（ａ）の保護層４に接着層８によって接着された保護基板７を有する型のものを示す図である。
（ｃ）前記（ｂ）の基板１と記録層２の間に基板下引き層３を有し、かつ基板１裏面にハードコート層５を有する型のものを示す図である。
【符号の説明】
１ 基板
２ 記録層
３ 基板下引き層
４ 保護層
５ ハードコート層
６ 金属反射層
７ 保護基板
８ 接着層[0001]
[Industrial application fields]
The present invention 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, information is recorded and reproduced, and additional recording is performed. The present invention relates to a possible information recording medium.
[0002]
[Prior art]
1. Prior art of data write-once disc (1) Using cyanine dye as recording material JP-A-57-82093 JP-A-58-56892
JP 58-11127 A JP 58-1114989
JP 59-85791 JP 60-83236
JP 60-89842 JP 61-25886 JP
(2) Using a phthalocyanine dye as a recording material JP 61-150243 JP 61-177287 A
JP 61-154888 JP 61-2446091
JP-A 62-39286 JP-A 63-37791
JP-A-63-39888
2. Prior art of write-once compact disc using a cyanine dye / metal reflective layer as a recording material JP-A-1-159842 JP-A-2-42652
JP-A-2-13656 JP-A-2-168446
[0003]
[Problems to be solved by the invention]
1. In the current write-once optical disk system (WORM, CD-R), the laser used has an oscillation wavelength of 770 to 790 nm, and the recording medium is set so that recording and reproduction can be performed at the above wavelength. In the future, as the amount of information increases, it is essential to increase the capacity of recording media. Accordingly, it is easily expected that the laser wavelength used for recording and reproduction will inevitably be shortened. However, a recording material that has excellent light resistance and storage stability and can be recorded and reproduced by an optical pickup using a laser of 700 nm or less has not been developed yet.
[0004]
2. The current CD-R disc system is configured so that recording and reproduction can be performed at an oscillation wavelength of a used laser of 770 to 790 nm. In this system as well, as described above, it is essential to increase the capacity, shorten the recording and reproducing wavelength. Since 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, reproduction is possible even if the laser wavelength is shortened in the future. . However, CD-R uses a dye having a maximum absorption wavelength at 680 nm to 750 nm in the recording layer, and is set to obtain a high reflectance from 770 nm to 790 nm because of its optical constant and film thickness configuration. In this wavelength range, the reflectivity is extremely low, 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.
[0005]
Therefore, the present invention provides a recording material for an optical recording medium, which is excellent in light resistance and storage stability, which can be applied to a high-density optical disk system using a semiconductor laser having an oscillation wavelength at a shorter wavelength than the conventional system. Another object of the present invention is to provide a recording material for a CD-R medium that can be recorded and reproduced by a current system and can be reproduced by a next-generation high-density optical disc system.
[0006]
[Means for Solving the Problems]
As a result of intensive studies on means for solving the above problems, the present inventors have made a recording layer mainly composed of a dye having a specific structure, and thereby used a high-density optical disk system using a semiconductor laser with an oscillation wavelength of 700 nm or less. In addition, by using the compound of the present invention mixed with an organic dye used as a recording material for current CD-R, a high reflectance can be obtained even in a wavelength region of 700 nm or less. The present invention has been found to be possible.
[0007]
Examples of the organic dye compound used in the present invention include those represented by the following general formula (1).
[Chemical 2]

[0008]
Wherein, M is a divalent, a trivalent or tetravalent metal atom, an oxygen atom, a halogen atom, may have either a _{(OSiR 15 R 16 R 17)} t, R 15 to R ₁₇ represents independently have a location substituent with good fats Zokusumi hydrocarbon group. t represents 2 . R _{1 to} R ₄ are each independently a phenyl group (hereinafter also referred to as a fluorine-containing phenyl group) substituted with at least a fluorine atom or a fluorine-containing alkyl group ( hereinafter also referred to as a fluorine-containing substituent). X _{1 to} X ₄ are a hydrogen atom or a halogen atom. ]
[0009]
In the compound of the formula (1), when all of X _{1 to} X ₄ are halogen, the decomposition point is lowered and the recording sensitivity is expected to be improved. As halogen, bromine and chlorine are particularly preferred.
[0010]
Further, as the fluorine-substituted alkyl Le group which is a substituent of the phenyl group of R ₁ to R ₄ in Equation (1), for example, trifluoromethyl group, trifluoroethyl group, difluoroethyl group, difluoropropyl group , A trifluoropropyl group, a tetrafluoropropyl group, a hexafluorobutyl group, or various perfluoroalkyl groups.
The fluorine-containing phenyl group of R _{1 to} R ₄ may be substituted with a group other than the fluorine-substituted alkyl. Specific examples of the substituent include an alkyl group, an alkoxy group, a nitro group, a cyano group, and a halogen atom. Among them, halogen is most preferable, and chlorine and bromine are preferable as the halogen.
The reason for this is that it contributes to the reduction of the decomposition point and can increase the sensitivity of the optical recording medium.
[0011]
In the compound of the formula (1), there are four isomers of the following formulas (A) to (D), and in the case of a mixture thereof, the amount of these isomers is adjusted when finely adjusting the characteristics such as the absorption wavelength. Can be finely adjusted, and the recording power margin when the film thickness is reduced can be increased.
[0012]
[Chemical 3]

Specific examples of the compounds used in the present invention are shown below. However, the compounds used in the present invention are not limited to these, and these compounds have four isomers as shown in the above (A) to (D). Of the compounds shown in Tables 1 to 7, those not included in the compound group defined in claims 1 to 3 are reference examples.
[0013]
[Formula 4]

[Table 1]

[0014]
[Table 2]

[0015]
[Table 3]

[0016]
[Table 4]

[0017]
[Table 5]

[0018]
[Table 6]

[0019]
[Table 7]

[0020]
In the present invention, when a short wavelength compatible CD-R medium is formed by mixing a dye having the absorption maximum wavelength at 680 nm to 750 nm and the dye of the present invention, the dyes described in the above-mentioned publications are used as they are. However, preferred examples of the dye having the maximum absorption wavelength at 680 nm to 750 nm include the following.
[0021]
(1) Cyanine dye represented by the following formula (2)

(Wherein R ₅ and R ₆ are alkyl groups having 1 to 3 carbon atoms.
R _7, R _8: an alkyl group which may have a substituent group having 1 to 6 carbon atoms.
X: Acid anion.
The aromatic ring may be condensed with other aromatic rings, alkyl,
It may be substituted with a halogen, an alkoxy group or an acyl group. )
[0022]
(2) Phthalocyanine dye represented by the following formula (3) or (4)

(Wherein M ₁ : Ni, Pd, Cu, Zn, Co, Mn, Fe, TiO, VO.
X _{5 to} X ₈ : α-position —OR, —SR, or a hydrogen atom, and all do not become a hydrogen atom.
R: a linear alkyl group having 3 to 12 carbon atoms which may have a substituent, a branched alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, or An aryl group which may have a substituent;
The benzene ring may have a substituent other than the above X _{5 to} X ₈ , and the substituent of the benzene ring in that case is hydrogen or halogen. )
[0023]
[Chemical 7]

(Wherein M ₂ : Si, Ge, In, Sn.
X _{9 to} X ₁₂ : α-position —OR, —SR, or a hydrogen atom, and all do not become a hydrogen atom.
R is the same as above.
_{Y 3, Y 4: -OSiRaRbRc,} -OCORa, -OPORaRb.
Ra, Rb, Rc: an alkyl group having 1 to 10 carbon atoms, an aryl group.
The benzene ring may have a substituent other than the above X _{9 to} X ₁₂ , and the substituent of the benzene ring in that case is hydrogen or halogen. )
(3) Azo metal chelate compound One or more azo metal chelate compounds of an azo compound represented by the following formula (5) and a metal, and preferable examples of the metal include Ni, Pt, Pd, Co, Cu, Zn, etc. are mentioned.
[0024]
[Chemical 8]

(Wherein A represents a residue which, together with the carbon and nitrogen atoms to which it is attached, forms a heterocyclic ring, B represents an aromatic with the two carbon atoms to which it is attached. Represents a residue that forms a ring or a heterocyclic ring, and X represents a group having an active hydrogen.)
[0025]
The mixing ratio of the dye of the present invention and the dye having the maximum absorption wavelength at 680 nm to 750 nm including the above specific examples is the dye of the present invention / the dye having absorption at 680 nm to 750 nm = 10/100 to 90/100, preferably Is 40/100 to 20/100. The thickness of the recording layer is 500 to 5 μm, preferably 1000 to 5000 mm.
The structure of the recording medium of the present invention is a structure diagram of a write-once optical disk (this structure may be a so-called air sandwich structure in which two sheets of FIG. 1 are bonded together, or a close-bonded structure). The structure of the CD-R medium shown in FIG. 2 may be used, or a structure in which two sheets are bonded together with an adhesive may be used. Furthermore, the layer structure for DVD-R shown in FIG. 3 may be used, or a structure in which two of them are bonded together may be used.
[0026]
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. Incidentally, 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.
[0027]
The recording layer is a recording layer that causes some optical change upon irradiation with laser light, and records information by the change, and the recording layer must contain the dye of the present invention. 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, phthalocyanine, squarylium, croconium, pyrylium, naphthoquinone, anthraquinone (indanthrene), xanthene, triphenylmethane, azulene, tetrahydro Examples thereof include choline-based, phenanthrene-based, triphenothiazine-based dyes, and metal complex compounds.
[0028]
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 is used in the form of dispersion mixing or lamination. be able to.
Furthermore, polymer 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 above dyes. For the purpose of improvement, stabilizers (for example, transition metal complexes), dispersants, flame retardants, lubricants, antistatic agents, surfactants, plasticizers and the like can be used together.
[0029]
The recording layer can be formed by ordinary means such as vapor deposition, sputtering, CVD or solvent coating. In the case of using the coating method, 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, dimethyl sulfoxide and the like Sulfoxides, 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, Pentane, cyclohexane, and hydrocarbons such as methylcyclohexane. The thickness of the recording layer is 100 to 10 μm, preferably 200 to 2000 μm.
[0030]
Undercoat layer 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 reflectance, and (5) from a solvent. It is used for the purpose of protecting the substrate, and (6) forming guide grooves, guide pits, and preformats. For the purpose of (1), polymer materials such as ionomer resins, polyamide resins, vinyl resins, natural resins, natural polymers, silicones, liquid rubbers, various polymer compounds, and silane coupling agents are used. For the purposes (2) and (3), there are inorganic compounds such as SiO, MgF, SiO ₂ , TiO, ZnO, TiN, SiN, etc. in addition to the above polymer materials, and also metals or semi-metals. Metals 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, Ag and the like, and organic thin films having 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.
[0031]
Metal reflective layer The metal reflective layer can be a single metal with high reflectivity and hardly corroded metal, semi-metal, etc. Examples of materials include Au, Ag, Cr, Ni, Al, Fe, Sn, etc. Au, Ag, and Al are most preferable from the viewpoint of reflectivity and 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.
[0032]
Protective layer, substrate surface hard coat layer protective layer and substrate surface hard coat layer protect (1) recording layer (reflection / absorption layer) from scratches, dust, dirt, etc. (2) Storage of recording layer (reflection / absorption layer) It is used for the purpose of improving stability and (3) improving reflectance. For these purposes, the materials shown for the undercoat layer can be used. Moreover, SiO, SiO ₂ , etc. 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 as the organic material. Thermal softening and heat melting resins such as butadiene resin, chloroprene rubber, wax, alkyd resin, drying oil and rosin 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, the undercoat layer, the protective layer, and the substrate surface hard coat layer are the same as in the recording layer, such as a stabilizer, a dispersant, a flame retardant, a lubricant, an antistatic agent, a surfactant, a plasticizer, and the like. Can be contained.
[0033]
When the protective substrate is irradiated with laser light from the protective substrate side, 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 material that can be used is exactly the same as the substrate material, and plastics such as polyester, acrylic resin, polyamide, polycarbonate resin, polyolefin resin, phenol resin, epoxy resin, and polyimide, or glass, ceramic, or metal can be used. it can.
[0034]
Any material can be used as long as it can bond two recording media, and in view of productivity, an ultraviolet curable adhesive or a hot melt adhesive is preferable.
[0035]
【Example】
Examples of the present invention will be described below. However, the present invention is not limited to these examples.
[0036]
Example 1
On a PMMA substrate having a thickness of 1.2 mm and a guide groove having a depth of 1200 mm, a full width at half maximum of 0.35 μm and a track pitch of 1.0 μm formed by a photopolymer, compound No. 1 was formed. A 1,2-dichloroethane solution of No. 1 was spinner coated to form a recording layer having a thickness of 900 mm to obtain a recording medium.
[0037]
Examples 2-8
In Example 1, compound no. No. 1 2, 9, 12, 13, 19, 26, and 29 were used to form a recording medium exactly as in Example 1.
[0038]
Comparative Example 1
In Example 1, Compound Example No. A recording medium was formed in the same manner as in Example 1 except that the following compounds were used instead of 1.
[Chemical 9]

[0039]
The recording media of Examples 1 to 8 and Comparative Example 1 were subjected to an evaluation test under the following conditions. The results are shown in Table 8 below.
<Recording conditions>
Laser oscillation wavelength: 650 nm
Recording frequency: 1.25 MHz
Recording linear velocity: 1.2m / sec
<Playback conditions>
Laser oscillation wavelength: 650 nm
Repower: 0.25 to 0.3 mW continuous optical scanning bandwidth: 30 KHz
<Light resistance test conditions>
Light resistance test: 40,000 Lux, Xe light, 20 hours continuous irradiation storage test: 85 ° C 85% 720 hours standing
[Table 8]

[0041]
Example 9
On an injection molded polycarbonate substrate having a depth of 1000 mm, a half width of 0.35 μm, and a guide groove having a track pitch of 1.0 μm and a thickness of 0.6 mm, Compound Example No. 2 was dissolved in a mixed solution of methylcyclohexane, 2-methoxyethanol, methylethylketone, and tetrahydrofuran to form a 1800 mm thick organic dye layer, and then a 2000 mm gold reflective layer was formed by sputtering. A protective layer having a thickness of 5 μm was provided thereon with an acrylic photopolymer, and a polycarbonate substrate having a thickness of 0.6 mm was further bonded thereon with a hot melt adhesive to obtain a recording medium.
[0042]
Examples 10-16
In Example 9, compound no. In place of compound 2, compound no. Using 4, 8, 9, 15, 17, 22, and 24, a recording medium was obtained in exactly the same manner as in Example 9.
[0043]
Comparative Example 2
In Example 9, as an organic thin film, Compound No. Instead of 2, a compound of the formula (6) of Comparative Example 1 was used as a recording medium.
[0044]
Comparative Example 3
In Example 9, as an organic thin film, Compound No. Instead of 2, a compound of the following formula (7) was used as a recording medium.
[Chemical Formula 10]

[0045]
A semiconductor laser beam having an oscillation wavelength of 635 nm and a beam diameter of 1.0 μm was used for the recording media of Examples 9 to 16 and Comparative Examples 2 to 3, and an EFM signal was recorded while tracking (linear velocity: 1.4 m / sec). Table 9 below shows the results of reproducing with continuous light of the same laser and observing the reproduced waveform.
[0046]
[Table 9]

[0047]
Example 17
On the 0.6 mm thick injection molded polycarbonate substrate having a guide groove with a depth of 1000 mm, a half width of 0.40 μm and a track pitch of 1.1 μm, the compound of formula (7) and compound No. 5 is mixed in a weight ratio of 1: 1, and this is dissolved in a mixed solvent of methylcyclohexane, 2-methoxyethanol, methyl ethyl ketone, and tetrahydrofuran, and applied with a spinner to form an organic dye layer having a thickness of 1600 mm, followed by sputtering. Then, a reflective layer of 2100 mm of gold was formed, and a protective layer of 7 μm was further formed thereon with an acrylic photopolymer to obtain a recording medium.
[0048]
Examples 18-19
In Example 17, the recording layer was prepared as Compound No. No. 5 instead of No. 5 respectively. 10 and 20 were used to obtain a recording medium exactly as in Example 17.
[0049]
Examples 20-21
In Example 17, the recording layer was prepared as Compound No. No. 5 instead of No. 5 respectively. A recording medium was obtained in exactly the same manner as in Example 17 except that compounds 8 and 24 were used and the compound of the following formula (8) was used instead of the compound of the above formula (7).
Embedded image

[Wherein X represents a group of the following formula (9). ]
Embedded image

[0050]
Examples 22-23
In Example 17, the recording layer was prepared as Compound No. No. 5 instead of No. 5 respectively. A recording medium was obtained in the same manner as in Example 17 except that the compounds of the following formula (10) were used in place of the compounds of formulas (7) and (14).
Embedded image

[0051]
Comparative Examples 4-6
A recording medium was obtained in the same manner as in Example 17 except that only the compound of the formula (7), only the compound of the formula (8), and only the compound of the formula (10) were used for the organic recording layer in Example 17.
[0052]
A semiconductor laser 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 4 to 6, and an EFM signal was recorded while tracking (linear velocity: 1.4 m / sec). Table 10 below shows the results of reproduction with a laser and continuous light of a semiconductor laser having an oscillation wavelength of 635 nm and a beam diameter of 1.1 μm and observing the reproduction waveform.
[0053]
[Table 10]

[0054]
【effect】
1. Claims 1-4
(1) An information recording medium that can be recorded and reproduced with a laser beam having a wavelength region of 700 nm or less and has excellent light resistance and storage stability can be provided.
(2) It was possible to provide an information recording medium that can be used as a CD-R in the current system and can reproduce recorded information even when it becomes a next-generation high-density optical disk system.
2. Claim 5
A recording and / or reproducing method capable of recording and / or reproducing with a short-wavelength recording light has been provided.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a configuration of a normal write-once optical recording medium.
2A is a view showing a type having a recording layer 2 on a substrate 1. FIG.
(B) It is a figure which shows the thing of the type | mold which has the undercoat layer 3 on the board | substrate 1 of said (a).
(C) It is a figure which shows the thing of the type | mold which has the protective layer 4 on the recording layer 2 of said (b).
(D) It is a figure which shows the thing of the type | mold which has the hard-coat layer 5 on the back surface of the board | substrate 1 of said (c).
FIG. 2 is a schematic cross-sectional view of a medium configuration for CD-R.
(A) It is a figure which shows the thing of the type | mold which has the recording layer 2, the metal reflective layer 6, and the protective layer 4 on the board | substrate 1. FIG.
(B) It is a figure which shows the thing of the type | mold which has the undercoat layer 3 on the board | substrate 1 of said (a).
(C) It is a figure which shows the thing of the type | mold which has the hard-coat layer 5 in the board | substrate 1 back surface of said (b).
FIG. 3 is a schematic cross-sectional view of a medium configuration for CVD-R.
(A) It is a figure which shows the thing of the type | mold which has the recording layer 2, the metal reflective layer 6, and the protective layer 4 on the board | substrate 1. FIG.
(B) It is a figure which shows the thing of the type | mold which has the protective substrate 7 adhere | attached by the contact bonding layer 8 on the protective layer 4 of said (a).
(C) It is a figure which shows the thing of the type | mold which has the board | substrate undercoat layer 3 between the board | substrate 1 and the recording layer 2 of said (b), and has the hard-coat layer 5 on the back surface of the board | substrate 1.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate 2 Recording layer 3 Substrate undercoat layer 4 Protective layer 5 Hard coat layer 6 Metal reflective layer 7 Protective substrate 8 Adhesive layer

Claims (5)

In setting only optical recording medium recording layer directly or through an undercoat layer on a substrate, an optical recording medium, wherein the recording layer contains at least one compound represented by the following structural formula (1) .

Wherein, M is a divalent, a trivalent or tetravalent metal atom, an oxygen atom, a halogen atom, may have either a _{(OSiR 15 R 16 R 17)} t, R 15 to R ₁₇ represents independently have a location substituent with good fats Zokusumi hydrocarbon group. t represents 2 . R _{1 to} R ₄ are each independently a phenyl group (hereinafter also referred to as a fluorine-containing phenyl group) substituted with at least a fluorine atom or a fluorine-containing alkyl group ( hereinafter also referred to as a fluorine-containing substituent). X _{1 to} X ₄ are a hydrogen atom or a halogen atom. ] The optical recording medium according to claim ₁ , wherein X _{1 to} X _{4 in} formula (1) are each independently bromine and / or chlorine. The optical recording medium according to claim 1 or 2, wherein the fluorine-containing phenyl group of R _{1 to} R _{4 in} the formula (1) is substituted with a halogen other than the fluorine-containing substituent. 4. The optical recording medium according to claim 1, wherein the recording layer comprises a mixed layer of a dye having a maximum absorption wavelength at 680 to 750 nm in addition to the compound represented by the formula (1). 5. An optical recording and / or reproducing method comprising irradiating a short wavelength light having a recording wavelength of 720 to 630 nm to an optical recording medium for recording 1, 2, 3 or 4.

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