JP3833840B2 - Positive photosensitive composition and positive photosensitive lithographic printing plate - Google Patents

Description

【００１６】
〔式(Ia)、(Ib)、及び(Ic)中、Ｒ¹ 及びＲ² は各々独立して、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、又は置換基を有していてもよいフェニル基を示し、Ｌ¹ は置換基を有していてもよいトリ、ペンタ、又はヘプタメチン基を示し、該ペンタ又はヘプタメチン基上の２つの置換基が互いに連結して炭素数５〜７のシクロアルケン環を形成していてもよく、キノリン環は置換基を有していてもよく、その場合、隣接する２つの置換基が互いに連結して縮合ベンゼン環を形成していてもよい。Ｘ^- は対アニオンを示す。〕
【００１７】
ここで、式(Ia)、(Ib)、及び(Ic)中のＲ¹ 及びＲ² における置換基としては、アルコキシ基、フェノキシ基、ヒドロキシ基、又はフェニル基等が挙げられ、Ｌ¹ における置換基としては、アルキル基、アミノ基、又はハロゲン原子等が挙げられ、キノリン環における置換基としては、アルキル基、アルコキシ基、ニトロ基、又はハロゲン原子等が挙げられる。
【００１８】
又、インドール系、及びベンゾチアゾール系色素としては、特に、下記一般式(II)で表されるものが好ましい。
【００１９】
【化２】

【００２０】
〔式(II)中、Ｙ¹ 及びＹ² は各々独立して、ジアルキルメチレン基又は硫黄原子を示し、Ｒ³ 及びＲ⁴ は各々独立して、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、又は置換基を有していてもよいフェニル基を示し、Ｌ² は置換基を有していてもよいトリ、ペンタ、又はヘプタメチン基を示し、該ペンタ又はヘプタメチン基上の２つの置換基が互いに連結して炭素数５〜７のシクロアルケン環を形成していてもよく、縮合ベンゼン環は置換基を有していてもよく、その場合、隣接する２つの置換基が互いに連結して縮合ベンゼン環を形成していてもよい。Ｘ^- は対アニオンを示す。〕
【００２１】
ここで、式(II)中のＲ³ 及びＲ⁴ における置換基としては、アルコキシ基、フェノキシ基、ヒドロキシ基、又はフェニル基等が挙げられ、Ｌ² における置換基としては、アルキル基、アミノ基、又はハロゲン原子等が挙げられ、ベンゼン環における置換基としては、アルキル基、アルコキシ基、ニトロ基、又はハロゲン原子等が挙げられる。
【００２２】
又、アミノベンゼン系色素としては、特に、下記一般式(III) で表されるものが好ましい。
【００２３】
【化３】

【００２４】
〔式(III) 中、Ｒ⁵ 、Ｒ⁶ 、Ｒ⁷ 、及びＲ⁸ は各々独立して、アルキル基を示し、Ｒ⁹ 及びＲ¹⁰は各々独立して、置換基を有していてもよいアリール基、フリル基、又はチエニル基を示し、Ｌ³ は置換基を有していてもよいモノ、トリ、又はペンタメチン基を示し、該トリ又はペンタメチン基上の２つの置換基が互いに連結して炭素数５〜７のシクロアルケン環を形成していてもよく、キノン環及びベンゼン環は置換基を有していてもよい。Ｘ^- は対アニオンを示す。〕
【００２５】
ここで、式(III) 中のＲ⁹ 及びＲ¹⁰として具体的には、フェニル基、１−ナフチル基、２−ナフチル基、２−フリル基、３−フリル基、２−チエニル基、３−チエニル基等が挙げられ、それらの置換基としては、アルキル基、アルコキシ基、ジアルキルアミノ基、ヒドロキシ基、又はハロゲン原子等が挙げられ、Ｌ³ における置換基としては、アルキル基、アミノ基、又はハロゲン原子等が挙げられ、キノン環及びベンゼン環における置換基としては、アルキル基、アルコキシ基、ニトロ基、又はハロゲン原子等が挙げられる。
【００２６】
又、ピリリウム系、及びチアピリリウム系色素としては、特に、下記一般式(IVa) 、(IVb) 、又は(IVc) で表されるものが好ましい。
【００２７】
【化４】

【００２８】
〔式(IVa) 、(IVa) 、及び(IVc) 中、Ｙ³ 及びＹ⁴ は各々独立して、酸素原子又は硫黄原子を示し、Ｒ¹¹、Ｒ¹²、Ｒ¹³、及びＲ¹⁴は各々独立して、水素原子又はアルキル基、又は、Ｒ¹¹とＲ¹³、及びＲ¹²とＲ¹⁴が互いに連結して炭素数５又は６のシクロアルケン環を形成していてもよく、Ｌ⁴ は置換基を有していてもよいモノ、トリ、又はペンタメチン基を示し、該トリ又はペンタメチン基上の２つの置換基が互いに連結して炭素数５〜７のシクロアルケン環を形成していてもよく、ピリリウム環及びチアピリリウム環は置換基を有していてもよく、その場合、隣接する２つの置換基が互いに連結して縮合ベンゼン環を形成していてもよい。Ｘ^- は対アニオンを示す。〕
【００２９】
ここで、式(IVa) 、(IVa) 、及び(IVc) のＬ⁴ における置換基としては、アルキル基、アミノ基、又はハロゲン原子等が挙げられ、ピリリウム環及びチアピリリウム環における置換基としては、フェニル基、ナフチル基等のアリール基等が挙げられる。
【００３０】
更に、アミニウム系、及びイモニウム系色素としては、Ｎ，Ｎ−ジアリールイミニウム塩骨格を少なくとも１個有するものが好ましく、特に、下記一般式(Va)、又は(Vb)で表されるものが好ましい。
【００３１】
【化５】

【００３２】
〔式(Va)、及び(Vb)中、Ｒ¹⁵、Ｒ¹⁶、Ｒ¹⁷、Ｒ¹⁸、Ｒ¹⁹、Ｒ²⁰、Ｒ²¹、及びＲ²²は各々独立して、水素原子、アルキル基、又はフェニル基を示し、キノン環及びベンゼン環は置換基を有していてもよい。Ｘ^- は対アニオンを示す。尚、式(Vb)中の電子結合（─）は他の電子結合との共鳴状態を示す。〕
【００３３】
ここで、式(Va)、及び(Vb)中のキノン環及びベンゼン環における置換基としては、アルキル基、アルコキシ基、アシル基、ニトロ基、又はハロゲン原子等が挙げられる。
【００３４】
尚、前記一般式(Ia 〜c)、(II)、(III) 、(IVa〜c)、及び(Va 〜b)における対アニオンＸ^- としては、例えば、Ｃｌ^- 、Ｂｒ^- 、Ｉ^- 、ＣｌＯ₄ ^- 、ＰＦ₆ ^- 、及び、ＢＦ₄ ^- 等の無機硼酸等の無機酸アニオン、ベンゼンスルホン酸、ｐ−トルエンスルホン酸、ナフタレンスルホン酸、酢酸、及び、メチル、エチル、プロピル、ブチル、フェニル、メトキシフェニル、ナフチル、ジフルオロフェニル、ペンタフルオロフェニル、チエニル、ピロリル等の有機基を有する有機硼酸等の有機酸アニオンを挙げることができる。
【００３５】
以上、前記一般式(Ia 〜c)で表されるキノリン系色素、前記一般式(II)で表されるインドール系又はベンゾチアゾール系色素、前記一般式(III) で表されるアミノベンゼン系色素、前記一般式(IVa〜c)で表されるピリリウム系又はチアピリリウム系色素、及び前記一般式(Va 〜b)で表されるアミニウム系又はイモニウム系色素の各具体例を以下に示す。
【００３６】
【化６】

【００３７】
【化７】

【００３８】
【化８】

【００３９】
【化９】

【００４０】
【化１０】

【００４１】
【化１１】

【００４２】
【化１２】

【００４３】
【化１３】

【００４４】
【化１４】

【００４５】
【化１５】

【００４６】
【化１６】

【００４７】
又、本発明のポジ型感光性組成物における（Ｂ）成分としてのノボラック樹脂は、フェノール性水酸基含有アルカリ可溶性樹脂として、この種感光性組成物のバインダー樹脂に慣用されているものであって、例えば、フェノール、ｏ−クレゾール、ｍ−クレゾール、ｐ−クレゾール、２，５−キシレノール、３，５−キシレノール、ｏ−エチルフェノール、ｍ−エチルフェノール、ｐ−エチルフェノール、プロピルフェノール、ｎ−ブチルフェノール、ｔｅｒｔ−ブチルフェノール、１−ナフトール、２−ナフトール、ピロカテコール、レゾルシノール、ハイドロキノン、ピロガロール、１，２，４−ベンゼントリオール、フロログルシノール、４，４’−ビフェニルジオール、２，２−ビス（４’−ヒドロキシフェニル）プロパン等のフェノール類の少なくとも１種を、酸性触媒下、例えば、ホルムアルデヒド、アセトアルデヒド、プロピオンアルデヒド、ベンズアルデヒド、フルフラール等のアルデヒド類（尚、ホルムアルデヒドに代えてパラホルムアルデヒドを、アセトアルデヒドに代えてパラアルデヒドを、用いてもよい。）、又は、アセトン、メチルエチルケトン、メチルイソブチルケトン等のケトン類、の少なくとも１種と重縮合させた樹脂であって、中で、本発明においては、フェノール類としてのフェノール、ｏ−クレゾール、ｍ−クレゾール、ｐ−クレゾール、２，５−キシレノール、３，５−キシレノール、レゾルシノールと、アルデヒド類又はケトン類としてのホルムアルデヒド、アセトアルデヒド、プロピオンアルデヒドとの重縮合体が好ましく、特に、ｍ−クレゾール：ｐ−クレゾール：２，５−キシレノール：３，５−キシレノール：レゾルシノールの混合割合がモル比で４０〜１００：０〜５０：０〜２０：０〜２０：０〜２０の混合フェノール類、又は、フェノール：ｍ−クレゾール：ｐ−クレゾールの混合割合がモル比で１〜１００：０〜７０：０〜６０の混合フェノール類と、ホルムアルデヒドとの重縮合体が好ましい。尚、本発明のポジ型感光性組成物は後述する溶剤抑止剤を含有することが好ましく、その場合は、ｍ−クレゾール：ｐ−クレゾール：２，５−キシレノール：３，５−キシレノール：レゾルシノールの混合割合がモル比で７０〜１００：０〜３０：０〜２０：０〜２０：０〜２０の混合フェノール類、又は、フェノール：ｍ−クレゾール：ｐ−クレゾールの混合割合がモル比で１０〜１００：０〜６０：０〜４０の混合フェノール類と、ホルムアルデヒドとの重縮合体が好ましい。
【００４８】
前記ノボラック樹脂は、ゲルパーミエーションクロマトグラフィー測定によるポリスチレン換算の重量平均分子量が、好ましくは１，５００〜２０，０００、更に好ましくは２，０００〜１５，０００、特に好ましくは３，０００〜１２，０００のものが用いられる。重量平均分子量が前記範囲よりよりも小さいとレジストとしての十分な塗膜が得られず、前記範囲よりも大きいとアルカリ現像液に対する溶解性が小さくなり、非画像部の抜けが不十分となってレジストのパターンが得られにくくなる傾向となる。
【００４９】
又、本発明のポジ型感光性組成物における（Ｃ）成分としての、（Ｂ）成分のノボラック樹脂を構成するフェノール類とは異なるフェノール性水酸基含有化合物としては、１個以上のベンゼン環を有する単環式、環集合式、縮合多環式等の一価、二価、三価等のフェノール類であって、具体的には、前記（Ｂ）成分において挙げたと同様のフェノール類の外、例えば、２，４，６−トリメチルフェノール、ｐ−メトキシフェノール、ｐ−カルボキシフェノール、ｐ−アセチルフェノール等の単環式、４−ヒドロキシフェニルフェニルメタン、ビス（４−ヒドロキシフェニル）メタン、ビス（４−ヒドロキシフェニル）フェニルメタン、１，１−ビス（４’−ヒドロキシフェニル）エタン、１，１，１−トリス（４’−ヒドロキシフェニル）エタン、１，１−ビス（４’−ヒドロキシフェニル）シクロヘキサン、４，４’−ジヒドロキシジフェニルエーテル、４，４’−ジヒドロキシジフェニルケトン、４，４’−ジヒドロキシジフェニルスルフィド、４，４’−ジヒドロキシジフェニルスルホキシド、４，４’−ジヒドロキシジフェニルスルホン類等の環集合式、９−アントロール、及び下記の構造で表される化合物(1) 、(2) 、(3) 等の縮合多環式等の化合物が挙げられ、中で、ベンゼン環の置換基としてアルキル基、アルコキシ基、アシル基、カルボキシ基を有するものが好ましく、炭素数１０以下のアルキル基、アルコキシ基を有するものが特に好ましい。
【００５０】
【化１７】

【００５１】
本発明における（Ｃ）成分としては、これらの化合物の外、２量体以上のオリゴマーをも対象とし得るが、その分子量は、好ましくは１，５００未満、更に好ましくは１，０００未満、特に好ましくは８００未満のものである。
【００５２】
尚、本発明における（Ｃ）成分としての前記フェノール性水酸基含有化合物は、ノボラック樹脂の原料フェノール類として知られているものであり、ノボラック樹脂製品中にも未反応物或いは副生オリゴマーとして含有されるものであるが、本発明において用いられる（Ｃ）成分は、組成物中の（Ｂ）成分のノボラック樹脂を構成するフェノール類とは異なるフェノール性水酸基含有化合物であることが必須であり、組成物中の（Ｂ）成分のノボラック樹脂を構成するフェノール類と同じフェノール性水酸基含有化合物では、本発明の目的を安定して達成することが困難となる。
【００５３】
本発明のポジ型感光性組成物は、（Ａ）成分の前記光熱変換物質、（Ｂ）成分の前記ノボラック樹脂、及び（Ｃ）成分の前記フェノール性水酸基含有化合物を基本組成し、この三成分の合計量に対する各成分の含有割合は、（Ａ）成分が０．１〜３０重量％、（Ｂ）成分が３０〜９９．４重量％、（Ｃ）成分が０．５〜４０重量％であるのが好ましく、（Ａ）成分が０．５〜２０重量％、（Ｂ）成分が５０〜９８．５重量％、（Ｃ）成分が１〜３０重量％であるのが更に好ましく、（Ａ）成分が１〜１２重量％、（Ｂ）成分が６３〜９７重量％、（Ｃ）成分が２〜２５重量％であるのが特に好ましい。
【００５７】
又、本発明のポジ型感光性組成物には、必要に応じて、例えば、ビクトリアピュアブルー（４２５９５）、クリスタルバイオレット（４２５５５）、クリスタルバイオレットラクトン、オーラミンＯ（４１０００）、カチロンブリリアントフラビン（ベーシック１３）、ローダミン６ＧＣＰ（４５１６０）、ローダミンＢ（４５１７０）、サフラニンＯＫ７０：１００（５０２４０）、エリオグラウシンＸ（４２０８０）、ファーストブラックＨＢ（２６１５０）、Ｎｏ．１２０／リオノールイエロー（２１０９０）、リオノールイエローＧＲＯ（２１０９０）、シムラーファーストイエロー８ＧＦ（２１１０５）、ベンジジンイエロー４Ｔ−５６４Ｄ（２１０９５）、シムラーファーストレッド４０１５（１２３５５）、リオノールレッドＢ４４０１（１５８５０）、ファーストゲンブルーＴＧＲ−Ｌ（７４１６０）、リオノールブルーＳＭ（２６１５０）等の顔料又は染料等の着色剤が含有されていてもよい。尚、ここで、前記の括弧内の数字はカラーインデックス（Ｃ．Ｉ．）を意味する。
【００５８】
本発明のポジ型感光性組成物における前記着色剤の含有割合は、０〜５０重量％であるのが好ましく、０．５〜３０重量％であるのが更に好ましく、１〜２０重量％であるのが特に好ましい。
【００５９】
本発明のポジ型感光性組成物には、前記成分以外に、例えば、塗布性改良剤、現像性改良剤、密着性改良剤、感度改良剤、感脂化剤等の通常用いられる各種の添加剤が更に、好ましくは１０重量％以下、更に好ましくは５重量％以下の範囲で含有されていてもよい。
【００６０】
本発明の前記ポジ型感光性組成物は、通常、前記各成分を適当な溶媒に溶解した溶液として支持体表面に塗布した後、加熱、乾燥することにより、支持体表面に感光性組成物層が形成されたポジ型感光性平版印刷版とされる。
【００６１】
ここで、その溶媒としては、使用成分に対して十分な溶解度を持ち、良好な塗膜性を与えるものであれば特に制限はないが、例えば、メチルセロソルブ、エチルセロソルブ、メチルセロソルブアセテート、エチルセロソルブアセテート等のセロソルブ系溶媒、プロピレングリコールモノメチルエーテル、プロピレングリコールモノエチルエーテル、プロピレングリコールモノブチルエーテル、プロピレングリコールモノメチルエーテルアセテート、プロピレングリコールモノエチルエーテルアセテート、プロピレングリコールモノブチルエーテルアセテート、ジプロピレングリコールジメチルエーテル等のプロピレングリコール系溶媒、酢酸ブチル、酢酸アミル、酪酸エチル、酪酸ブチル、ジエチルオキサレート、ピルビン酸エチル、エチル−２−ヒドロキシブチレート、エチルアセトアセテート、乳酸メチル、乳酸エチル、３−メトキシプロピオン酸メチル等のエステル系溶媒、ヘプタノール、ヘキサノール、ジアセトンアルコール、フルフリルアルコール等のアルコール系溶媒、シクロヘキサノン、メチルアミルケトン等のケトン系溶媒、ジメチルホルムアミド、ジメチルアセトアミド、Ｎ−メチルピロリドン等の高極性溶媒、酢酸、あるいはこれらの混合溶媒、更にはこれらに芳香族炭化水素を添加したもの等が挙げられる。溶媒の使用割合は、感光性組成物の総量に対して、通常、重量比で１〜２０倍程度の範囲である。
【００６２】
又、その塗布方法としては、従来公知の方法、例えば、回転塗布、ワイヤーバー塗布、ディップ塗布、エアーナイフ塗布、ロール塗布、ブレード塗布、及びカーテン塗布等を用いることができる。塗布量は用途により異なるが、乾燥膜厚として、通常、０．３〜７μｍ、好ましくは０．５〜５μｍ、特に好ましくは１〜３μｍの範囲とする。尚、その際の乾燥温度としては、例えば、３０〜１７０℃程度、好ましくは４０〜１５０℃程度が採られる。
【００６３】
尚、本発明の効果を一層確実ならしめるために、例えば、４０〜１００℃程度、好ましくは４０〜７０℃程度の温度で、１分〜５０時間程度、好ましくは３０分〜２０時間程度の加熱処理を施すことが好ましい。
【００６４】
又、その支持体としては、アルミニウム、亜鉛、銅、鋼等の金属板、アルミニウム、亜鉛、銅、鉄、クロム、ニッケル等をメッキ又は蒸着した金属板、紙、樹脂を塗布した紙、アルミニウム等の金属箔を貼着した紙、プラスチックフィルム、親水化処理したプラスチックフィルム、及びガラス板等が挙げられる。中で、好ましいのはアルミニウム板であり、塩酸又は硝酸溶液中での電解エッチング又はブラシ研磨による砂目立て処理、硫酸溶液中での陽極酸化処理、及び必要に応じて封孔処理等の表面処理が施されたアルミニウム板がより好ましい。又、支持体表面の粗さとしては、ＪＩＳ Ｂ０６０１に規定される平均粗さＲ_a で、通常、０．３〜１．０μｍ、好ましくは０．４〜０．８μｍ程度とする。
【００６５】
本発明でのポジ型感光性組成物層を画像露光する光源としては、主として、ＨｅＮｅレーザー、アルゴンイオンレーザー、ＹＡＧレーザー、ＨｅＣｄレーザー、半導体レーザー、ルビーレーザー等のレーザー光源が挙げられるが、特に、光を吸収して発生した熱により画像形成させる場合には、６５０〜１３００ｎｍの近赤外レーザー光線を発生する光源が好ましく、例えば、ルビーレーザー、ＹＡＧレーザー、半導体レーザー、ＬＥＤ等の固体レーザーを挙げることができ、特に、小型で長寿命な半導体レーザーやＹＡＧレーザーが好ましい。これらの光源により、通常、走査露光した後、現像液にて現像し画像が形成される。
【００６６】
尚、レーザー光源は、通常、レンズにより集光された高強度の光線（ビーム）として感光性組成物層表面を走査するが、それに感応する本発明での感光性組成物層の感度特性（ｍＪ／ｃｍ² ）は受光するレーザービームの光強度（ｍＪ／ｓ・ｃｍ² ）に依存することがある。ここで、レーザービームの光強度は、光パワーメーターにより測定したレーザービームの単位時間当たりのエネルギー量（ｍＪ／ｓ）を感光性組成物層表面におけるレーザービームの照射面積（ｃｍ² ）で除することにより求めることができる。レーザービームの照射面積は、通常、レーザーピーク強度の１／ｅ² 強度を越える部分の面積で定義されるが、簡易的には相反則を示す感光性組成物を感光させて測定することもできる。
【００６７】
本発明において、光源の光強度としては、２．０×１０⁶ ｍＪ／ｓ・ｃｍ² 以上とすることが好ましく、１．０×１０⁷ ｍＪ／ｓ・ｃｍ² 以上とすることが特に好ましい。光強度が前記範囲であれば、本発明でのポジ型感光性組成物層の感度特性を向上させ得る、走査露光時間を短くすることができ実用的に大きな利点となる。
【００６８】
本発明の前記ポジ型感光性平版印刷版を画像露光したポジ型感光体の現像に用いる現像液としては、例えば、珪酸ナトリウム、珪酸カリウム、珪酸リチウム、珪酸アンモニウム、メタ珪酸ナトリウム、メタ珪酸カリウム、水酸化ナトリウム、水酸化カリウム、水酸化リチウム、炭酸ナトリウム、重炭酸ナトリウム、炭酸カリウム、第二燐酸ナトリウム、第三燐酸ナトリウム、第二燐酸アンモニウム、第三燐酸アンモニウム、硼酸ナトリウム、硼酸カリウム、硼酸アンモニウム等の無機アルカリ塩、モノメチルアミン、ジメチルアミン、トリメチルアミン、モノエチルアミン、ジエチルアミン、トリエチルアミン、モノイソプロピルアミン、ジイソプロピルアミン、モノブチルアミン、モノエタノールアミン、ジエタノールアミン、トリエタノールアミン、モノイソプロパノールアミン、ジイソプロパノールアミン等の有機アミン化合物の０．１〜５重量％程度の水溶液からなるアルカリ現像液を用いる。中で、無機アルカリ塩である珪酸ナトリウム、珪酸カリウム等のアルカリ金属の珪酸塩が好ましい。尚、現像液には、必要に応じて、アニオン性界面活性剤、ノニオン性界面活性剤、両性界面活性剤等の界面活性剤や、アルコール等の有機溶媒を加えることができる。
【００６９】
尚、現像は、浸漬現像、スプレー現像、ブラシ現像、超音波現像等により、通常、好ましくは１０〜５０℃程度、特に好ましくは１５〜４５℃程度の温度でなされる。
【００７０】
【実施例】
以下、本発明を実施例によりさらに具体的に説明するが、本発明はその要旨を越えない限り、以下の実施例に限定されるものではない。
【００７１】
実施例１〜１２、比較例１
アルミニウム板（厚さ０．２４ｍｍ）を、５重量％の水酸化ナトリウム水溶液中で６０℃で１分間脱脂処理を行った後、０．５モル／リットルの濃度の塩酸水溶液中で、温度２５℃、電流密度６０Ａ／ｄｍ² 、処理時間３０秒の条件で電解エッチング処理を行った。次いで５重量％の水酸化ナトリウム水溶液中で６０℃、１０秒間のデスマット処理を施した後、２０重量％硫酸溶液中で、温度２０℃、電流密度３Ａ／ｄｍ² 、処理時間１分の条件で陽極酸化処理を行った。更に、８０℃の熱水で２０秒間熱水封孔処理を行い、平版印刷版支持体用のアルミニウム板を作製した。
【００７２】
得られたアルミニウム板支持体表面に、（Ａ）成分として前記具体例(II-9)で示したインドール系色素３重量部、（Ｂ）成分として、フェノール：ｍ−クレゾール：ｐ−クレゾールの混合割合がモル比で５０：３０：２０の混合フェノール類と、ホルムアルデヒドとの重縮合体からなり、重量平均分子量９，４００のノボラック樹脂（住友デュレズ社製「ＳＫ−１８８」）１００重量部、（Ｃ）成分として表１に示すフェノール性水酸基含有化合物を表１に示す量、及び、クリスタルバイオレットラクトン３重量部を、メチルセロソルブ１０００重量部に溶解した塗布液をワイヤーバーを用いて塗布し、８５℃で２分間乾燥させた後、５５℃で安定化させることにより、塗膜量２．４ｇ／ｍ² のポジ型感光性組成物層を有するポジ型感光性平版印刷版を作製した。
【００７３】
得られたポジ型感光性平版印刷版を回転ドラムに取り付け、ドラムを回転させながら、黄色灯下で、波長８３０ｎｍ、出力４０ｍＷの半導体レーザー（アプライドテクノ社製）を２５μｍのビームスポット径にて照射することにより走査露光し、次いで、アルカリ現像液（コニカ社製「ＳＤＲ−１」の６倍希釈液）に２８℃で３０秒浸漬した後、水洗し現像を行った。
【００７４】
得られたポジ画像が２５μｍ幅を与えるときのドラムの最大回転数から感度をエネルギー値（ｍＪ／ｃｍ² ）として求め、以下の基準で感度を評価し、結果を表１に示した。
【００７５】
Ａ：エネルギー値１００ｍＪ／ｃｍ² 以下
Ｂ：エネルギー値１００ｍＪ／ｃｍ² 超過、１２０ｍＪ／ｃｍ² 以下
Ｃ：エネルギー値１２０ｍＪ／ｃｍ² 超過、１４０ｍＪ／ｃｍ² 以下
Ｄ：エネルギー値１４０ｍＪ／ｃｍ² 超過、１６０ｍＪ／ｃｍ² 以下
Ｅ：エネルギー値１６０ｍＪ／ｃｍ² 超過
【００７６】
更に、得られたポジ画像について、非露光部における現像前後の反射濃度を反射濃度計（マクベス社製「ＲＤ−５１４」）を用いて測定し、感光性組成物層形成前の支持体表面の反射濃度の値を差引いたそれぞれの値の比から残膜率を求め、以下の基準で評価し、結果を表１に示した。
【００７７】
Ａ：残膜率０．９５以上
Ｂ：残膜率０．９０以上、０．９５未満
Ｃ：残膜率０．８０以上、０．９０未満
Ｄ：残膜率０．７０以上、０．８０未満
Ｅ：残膜率０．７０未満
【００７８】
【表１】

【００７９】
尚、前記で得られたポジ型感光性平版印刷版は、白色蛍光灯（三菱電機社製３６Ｗ白色蛍光灯「ネオルミスーパーＦＬＲ４０Ｓ−Ｗ／Ｍ／３６」）の４００ルクスの光強度照射下に１０時間放置した後、前記と同様の現像処理を行った場合、いずれの実施例及び比較例においても実質的な膜減りはなく、白色蛍光灯下における取扱性は良好であった。
【００８０】
実施例１３〜１６、比較例２
前記実施例で用いたと同じアルミニウム板支持体表面に、（Ａ）成分として前記実施例で用いたと同じインドール系色素４重量部、（Ｂ）成分として前記実施例で用いたと同じノボラック樹脂１００重量部、（Ｃ）成分として表２に示すフェノール性水酸基含有化合物を表２に示す量、及び、クリスタルバイオレットラクトン１０重量部を、シクロヘキサノン１２００重量部に溶解した塗布液を用いた外は、前記実施例と同様にしてポジ型感光性平版印刷版を作製した。
【００８１】
得られたポジ型感光性平版印刷版につき、波長８３０ｎｍの半導体レーザーを光源とする露光装置（クレオ社製、「Ｔｒｅｎｄ Ｓｅｔｔｅｒ ３２４４Ｔ」）を用いて各種の露光エネルギーで２００線、１〜９９％の網点画像を画像露光し、次いで、アルカリ現像液（富士写真フィルム社製「ＤＰ−４」の８倍希釈液）に２８℃で３０秒浸漬した後、水洗し現像を行うことにより、１〜９９％の網点画像を再現させた印刷版を作製し、そのときの感度を３％の網点が再現する露光エネルギー量として求め、結果を表２に示した。
【００８２】
【表２】

【００８３】
【発明の効果】
本発明によれば、紫外線領域の光に対しては感応せず、白色蛍光灯下における取扱性に優れると共に、近赤外線領域の光に対して感応し、感度、及び画像部と非画像部とのコントラストに優れ、画像部の残膜率も十分に保持されるポジ型感光性組成物及びポジ型感光性平版印刷版を提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention is mainly used in photosensitive lithographic printing plates, proofs for simple proof printing, copper etching resists for wiring boards and gravure, color filter resists used in flat display production, photoresists for LSI production, etc. The present invention relates to a positive photosensitive composition and a positive photosensitive lithographic printing plate that are highly sensitive to light in a region, and in particular, a positive photosensitive composition and a positive photosensitive composition that are suitable for direct plate making using a semiconductor laser, a YAG laser, or the like. Related to lithographic printing plates.
[0002]
[Prior art]
Conventionally, as the positive photosensitive composition, for example, an o-quinonediazide group-containing compound that becomes insoluble in alkali by generating indene carboxylic acid upon irradiation with light, an organic polymer substance having an o-nitrocarbinol ester group, or light There are known compositions and the like of a compound (photoacid generator) that generates an acid by an acid and a compound that is hydrolyzed by an acid and becomes alkali-soluble.
[0003]
On the other hand, with the advancement of computer image processing technology, a photosensitive or thermal direct plate making system that directly forms a resist image by laser light or a thermal head, etc., without outputting digital image information to a silver salt mask film is attracting attention. Has been. In particular, a high-resolution laser-sensitive direct plate-making system using a high-power semiconductor laser, a YAG laser, or the like is strongly desired to be realized from the viewpoints of downsizing, ambient light during plate-making work, and plate material cost. Yes.
[0004]
On the other hand, conventionally, as an image forming method using laser sensitivity or heat sensitivity, a method of forming a color material image using a sublimation transfer dye and a method of preparing a lithographic printing plate are known. Specifically, for example, a method of producing a lithographic printing plate using a crosslinking reaction of a diazo compound, a method of producing a lithographic printing plate using a decomposition reaction of nitrocellulose, and the like are known.
[0005]
In recent years, a technique in which a long-wavelength light-absorbing dye is combined with a chemically amplified photoresist has been scattered. For example, JP-A-6-43633 discloses an image containing a specific squarylium dye, a photoacid generator, and a binder. JP-A-7-20629 discloses an image-forming material containing an infrared-absorbing dye, a latent Bronsted acid, a resole resin, and a novolac resin, and JP-A-7-271029 discloses a forming material. An image forming material using an s-triazine compound instead of the latent Bronsted acid is further disclosed in JP-A-7-285275 as a binder, a substance that absorbs light and generates heat, and a heat An image forming material is disclosed that includes a substance that is degradable and substantially reduces the solubility of the binder in a state where it does not decompose.
[0006]
In addition, these conventional techniques are sensitive to light in the ultraviolet region, and the reaction proceeds during handling under a white fluorescent lamp, so that it is difficult to obtain a stable quality product. JP-A-9-43847 contains a resin that is hardly soluble in an alkali developer and an infrared absorber, and is heated by infrared irradiation or the like to change its crystallinity and become alkali-soluble. The positive type composition that does not change is contained in WO97 / 39894, and contains an aqueous developable polymer and a compound that inhibits the aqueous developability of the polymer. Heat sensitive positive compositions that do not change upon irradiation are each disclosed.
[0007]
These positive compositions disclosed in JP-A-9-43847 and WO97 / 39894 contain a compound that undergoes a chemical change upon exposure, and the chemical change causes a difference in solubility between the exposed and unexposed areas. Unlike the composition in the prior art described above, which causes a difference in solubility due to a change other than a chemical change and does not contain a compound sensitive to light in the ultraviolet region, It has advantages such as excellent handleability.
[0008]
However, according to the study by the present inventors, in the negative photosensitive composition that requires heat treatment after exposure, the image obtained by the processing conditions is not always stable in the above-described conventional technique, In a positive photosensitive composition that does not require heat treatment after exposure, the sensitivity and the contrast between the image part (non-exposed part) and the non-image part (exposed part) are insufficient. It has problems such as not being sufficiently removed, and the remaining film ratio of the image area is not sufficiently maintained. In particular, changes other than chemical changes may cause a difference in solubility between the exposed and unexposed areas. In the positive compositions disclosed in JP-A-9-43847 and WO97 / 39894, it has been found that the tendency is remarkable.
[0009]
On the other hand, the applicant of the present invention does not contain a compound sensitive to light in the ultraviolet region and is a simple system that cannot expect photochemical changes between a photothermal conversion substance and an alkali-soluble resin with respect to light in the near infrared region. The inventors have found that a photosensitive composition capable of forming a positive image that has solved the above-mentioned problems can be obtained, and previously filed a patent application (Japanese Patent Application No. 9-205789), and are currently considering further improvements. It was.
[0010]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described prior art, is insensitive to light in the ultraviolet region, has excellent handleability under white fluorescent lamps, sensitivity, and image and non-image areas. It is an object to provide a positive photosensitive composition and a positive photosensitive lithographic printing plate that are excellent in contrast with the above and have a sufficient remaining film ratio in the image area.
[0011]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems in a system that does not contain a compound sensitive to light in the ultraviolet region, the present inventors have mainly developed a photothermal conversion substance and a specific phenolic hydroxyl group-containing compound for light in the near infrared region. The present invention has been completed by finding that a composition using a binder resin together with a binder resin can achieve the above-mentioned object. That is, the present invention comprises the following components (A), (B), and (C): The gist is a positive photosensitive composition containing, and a positive photosensitive lithographic printing plate in which a layer made of the photosensitive composition is formed on a support surface.
(A) Photothermal conversion material that absorbs light from an image exposure light source and converts it into heat (B) Novolak resin (C) A phenolic hydroxyl group-containing compound different from the phenols constituting the novolak resin of component (B)
DETAILED DESCRIPTION OF THE INVENTION
As the component (A) in the positive photosensitive composition of the present invention, the light-to-heat conversion substance that absorbs light from an image exposure light source and converts it into heat is particularly a compound that can convert the absorbed light into heat. Although not limited, organic or inorganic pigments and dyes having an absorption band in part or all of the near-infrared region in the wavelength range of 650 to 1300 nm, organic pigments, metals, metal oxides, metal carbides, metal borides and the like can be mentioned. Of these, light absorbing dyes are particularly effective. These light-absorbing dyes efficiently absorb light in the above-mentioned wavelength range, but hardly absorb light in the ultraviolet region, or are not substantially sensitive to absorption, and are weak by ultraviolet rays contained in white light. Is a compound having no action of modifying the photosensitive composition.
[0013]
Typical examples of these light-absorbing dyes include so-called cyanine dyes in a broad sense in which a heterocyclic ring containing a nitrogen atom, an oxygen atom, or a sulfur atom is bonded with polymethine (-CH =) _n. Specifically, for example, quinoline (so-called cyanine), indole (so-called indocyanine), benzothiazole (so-called thiocyanine), aminobenzene (so-called polymethine), pyrylium Type, thiapyrylium type, squarylium type, croconium type, azurenium type, etc., among which quinoline type, indole type, benzothiazole type, aminobenzene type, pyrylium type, or thiapyrylium type are preferable, and in addition, aminium Typical dyes such as those based on dye, imonium, phthalocyanine and anthraquinone Among them, in, aminium, immonium type dyes are preferred.
[0014]
In the present invention, among the cyanine dyes, those represented by the following general formula (Ia), (Ib), or (Ic) are particularly preferable as the quinoline dyes.
[0015]
[Chemical 1]

[0016]
[In the formulas (Ia), (Ib), and (Ic), R ¹ and R ² are each independently an optionally substituted alkyl group or an optionally substituted alkenyl group. , An alkynyl group that may have a substituent, or a phenyl group that may have a substituent, L ¹ represents a tri, penta, or heptamethine group that may have a substituent, Two substituents on the penta or heptamethine group may be linked to each other to form a cycloalkene ring having 5 to 7 carbon atoms, and the quinoline ring may have a substituent, in which case These two substituents may be linked to each other to form a condensed benzene ring. X ⁻ represents a counter anion. ]
[0017]
Preferable examples of the substituent in formula (Ia), R ¹ and R ² in (Ib), and (Ic), an alkoxy group, a phenoxy group, hydroxy group, or a phenyl group and the like, substitution of L ¹ Examples of the group include an alkyl group, an amino group, and a halogen atom. Examples of the substituent in the quinoline ring include an alkyl group, an alkoxy group, a nitro group, and a halogen atom.
[0018]
Further, as the indole and benzothiazole dyes, those represented by the following general formula (II) are particularly preferable.
[0019]
[Chemical 2]

[0020]
[In Formula (II), Y ¹ and Y ² each independently represent a dialkylmethylene group or a sulfur atom, and R ³ and R ⁴ each independently represent an alkyl group which may have a substituent, An alkenyl group which may have a substituent, an alkynyl group which may have a substituent, or a phenyl group which may have a substituent, L ² may have a substituent A good tri, penta, or heptamethine group, and two substituents on the penta or heptamethine group may be linked to each other to form a C5-C7 cycloalkene ring, and the condensed benzene ring is a substituent In this case, two adjacent substituents may be connected to each other to form a condensed benzene ring. X ⁻ represents a counter anion. ]
[0021]
Here, examples of the substituent in R ³ and R ⁴ in the formula (II) include an alkoxy group, a phenoxy group, a hydroxy group, and a phenyl group, and the substituent in L ² includes an alkyl group and an amino group. Or a halogen atom, and the substituent on the benzene ring includes an alkyl group, an alkoxy group, a nitro group, or a halogen atom.
[0022]
As the aminobenzene dye, those represented by the following general formula (III) are particularly preferable.
[0023]
[Chemical 3]

[0024]
[In the formula (III), R ⁵ , R ⁶ , R ⁷ and R ⁸ each independently represents an alkyl group, and R ⁹ and R ¹⁰ may each independently have a substituent. An aryl group, a furyl group, or a thienyl group, L ³ represents an optionally substituted mono, tri, or pentamethine group, and two substituents on the tri or pentamethine group are linked to each other. A C5-C7 cycloalkene ring may be formed, and the quinone ring and the benzene ring may have a substituent. X ⁻ represents a counter anion. ]
[0025]
Here, specific examples of R ⁹ and R ¹⁰ in formula (III) include a phenyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-furyl group, a 3-furyl group, a 2-thienyl group, 3- Thienyl group and the like, and examples of the substituent include an alkyl group, an alkoxy group, a dialkylamino group, a hydroxy group, and a halogen atom, and the substituent in L ³ includes an alkyl group, an amino group, or A halogen atom etc. are mentioned, As a substituent in a quinone ring and a benzene ring, an alkyl group, an alkoxy group, a nitro group, or a halogen atom etc. are mentioned.
[0026]
As the pyrylium-based and thiapyrylium-based dyes, those represented by the following general formula (IVa), (IVb), or (IVc) are particularly preferable.
[0027]
[Formula 4]

[0028]
[In formulas (IVa), (IVa) and (IVc), Y ³ and Y ⁴ each independently represent an oxygen atom or a sulfur atom, and R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are each independently A hydrogen atom or an alkyl group, or R ¹¹ and R ¹³ , and R ¹² and R ¹⁴ may be connected to each other to form a cycloalkene ring having 5 or 6 carbon atoms, and L ⁴ is a substituent. A mono-, tri-, or pentamethine group that may have a substituent, and two substituents on the tri- or pentamethine group may be linked to each other to form a C5-C7 cycloalkene ring, The pyrylium ring and the thiapyrylium ring may have a substituent, and in that case, two adjacent substituents may be connected to each other to form a condensed benzene ring. X ⁻ represents a counter anion. ]
[0029]
Here, examples of the substituent in L ⁴ in the formulas (IVa), (IVa), and (IVc) include an alkyl group, an amino group, and a halogen atom, and the substituents in the pyrylium ring and the thiapyrylium ring include Examples thereof include aryl groups such as a phenyl group and a naphthyl group.
[0030]
Further, as the aminium-based and imonium-based dyes, those having at least one N, N-diaryliminium salt skeleton are preferable, and those represented by the following general formula (Va) or (Vb) are particularly preferable. .
[0031]
[Chemical formula 5]

[0032]
[In the formulas (Va) and (Vb), R ¹⁵ , R ¹⁶ , R ¹⁷ , R ¹⁸ , R ¹⁹ , R ²⁰ , R ²¹ , and R ²² are each independently a hydrogen atom, an alkyl group, or phenyl. A quinone ring and a benzene ring may have a substituent. X ⁻ represents a counter anion. In addition, the electronic bond (-) in Formula (Vb) shows the resonance state with another electronic bond. ]
[0033]
Here, examples of the substituent in the quinone ring and the benzene ring in the formulas (Va) and (Vb) include an alkyl group, an alkoxy group, an acyl group, a nitro group, and a halogen atom.
[0034]
The counter anions X ⁻ in the general formulas (Ia to c), (II), (III), (IVa to c), and (Va to b) are, for example, Cl ⁻ , Br ⁻ , I ⁻ , Inorganic acid anions such as inorganic boric acid such as ClO ₄ ⁻ , PF ₆ ⁻ , and BF ₄ ⁻ , benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, acetic acid, and methyl, ethyl, propyl, butyl, phenyl And organic acid anions such as organic boric acid having an organic group such as methoxyphenyl, naphthyl, difluorophenyl, pentafluorophenyl, thienyl, and pyrrolyl.
[0035]
The quinoline dyes represented by the general formulas (Ia to c), the indole or benzothiazole dyes represented by the general formula (II), and the aminobenzene dyes represented by the general formula (III) Specific examples of the pyrylium or thiapyrylium dyes represented by the general formulas (IVa to c) and the aminium or imonium dyes represented by the general formulas (Va to b) are shown below.
[0036]
[Chemical 6]

[0037]
[Chemical 7]

[0038]
[Chemical 8]

[0039]
[Chemical 9]

[0040]
[Chemical Formula 10]

[0041]
Embedded image

[0042]
Embedded image

[0043]
Embedded image

[0044]
Embedded image

[0045]
Embedded image

[0046]
Embedded image

[0047]
Further, the novolak resin as the component (B) in the positive photosensitive composition of the present invention is commonly used as a phenolic hydroxyl group-containing alkali-soluble resin in the binder resin of this type of photosensitive composition, For example, phenol, o-cresol, m-cresol, p-cresol, 2,5-xylenol, 3,5-xylenol, o-ethylphenol, m-ethylphenol, p-ethylphenol, propylphenol, n-butylphenol, tert-Butylphenol, 1-naphthol, 2-naphthol, pyrocatechol, resorcinol, hydroquinone, pyrogallol, 1,2,4-benzenetriol, phloroglucinol, 4,4′-biphenyldiol, 2,2-bis (4 ′) -Pheno such as hydroxyphenyl) propane At least one kind of aldehydes may be used in an acidic catalyst, for example, aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, furfural, etc. Or a resin polycondensed with at least one of ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, wherein in the present invention, phenol as phenols, o-cresol, Preferred is a polycondensate of m-cresol, p-cresol, 2,5-xylenol, 3,5-xylenol, resorcinol with formaldehyde, acetaldehyde or propionaldehyde as aldehydes or ketones, particularly m- Mixed phenols having a mixing ratio of cresol: p-cresol: 2,5-xylenol: 3,5-xylenol: resorcinol in a molar ratio of 40 to 100: 0 to 50: 0 to 20: 0 to 20: 0 to 20, Alternatively, a polycondensate of mixed phenols having a mixing ratio of phenol: m-cresol: p-cresol in a molar ratio of 1 to 100: 0 to 70: 0 to 60 and formaldehyde is preferable. In addition, it is preferable that the positive photosensitive composition of this invention contains the solvent inhibitor mentioned later, and in that case, m-cresol: p-cresol: 2,5-xylenol: 3,5-xylenol: resorcinol The mixing ratio is 70 to 100: 0 to 30: 0 to 20: 0 to 20: 0 to 20 in molar ratio, or the mixing ratio of phenol: m-cresol: p-cresol is 10 to 10 in molar ratio. A polycondensate of 100: 0 to 60: 0 to 40 mixed phenols with formaldehyde is preferred.
[0048]
The novolak resin has a polystyrene-reduced weight average molecular weight of preferably 1,500 to 20,000, more preferably 2,000 to 15,000, and particularly preferably 3,000 to 12,000, as measured by gel permeation chromatography. 000 is used. If the weight average molecular weight is smaller than the above range, a sufficient coating film as a resist cannot be obtained. If the weight average molecular weight is larger than the above range, the solubility in an alkali developer is reduced, and the non-image area is insufficiently omitted. It tends to be difficult to obtain a resist pattern.
[0049]
In addition, the phenolic hydroxyl group-containing compound different from the phenols constituting the novolak resin of the component (B) as the component (C) in the positive photosensitive composition of the present invention has one or more benzene rings. Monovalent, divalent, trivalent, etc. phenols such as monocyclic, ring assembly, condensed polycyclic, etc., specifically, in addition to the same phenols as mentioned in the component (B), For example, monocyclic such as 2,4,6-trimethylphenol, p-methoxyphenol, p-carboxyphenol, p-acetylphenol, 4-hydroxyphenylphenylmethane, bis (4-hydroxyphenyl) methane, bis (4 -Hydroxyphenyl) phenylmethane, 1,1-bis (4′-hydroxyphenyl) ethane, 1,1,1-tris (4′-hydroxyphenyl) ethane 1,1-bis (4′-hydroxyphenyl) cyclohexane, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl ketone, 4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxydiphenyl sulfoxide, Compounds such as 4,4′-dihydroxydiphenyl sulfones and the like, condensed polycyclic compounds such as 9-anthrol, and compounds (1), (2) and (3) represented by the following structures: Among them, those having an alkyl group, an alkoxy group, an acyl group or a carboxy group as substituents on the benzene ring are preferred, and those having an alkyl group or alkoxy group having 10 or less carbon atoms are particularly preferred.
[0050]
Embedded image

[0051]
In addition to these compounds, the component (C) in the present invention may be a dimer or higher oligomer, but its molecular weight is preferably less than 1,500, more preferably less than 1,000, and particularly preferably. Is less than 800.
[0052]
The phenolic hydroxyl group-containing compound as the component (C) in the present invention is known as a starting phenol for novolak resin, and is also contained in the novolak resin product as an unreacted product or by-product oligomer. However, it is essential that the component (C) used in the present invention is a phenolic hydroxyl group-containing compound different from the phenols constituting the novolak resin of the component (B) in the composition. With the same phenolic hydroxyl group-containing compound as the phenols constituting the novolak resin of the component (B) in the product, it is difficult to stably achieve the object of the present invention.
[0053]
The positive photosensitive composition of the present invention comprises, as a basic composition, the photothermal conversion substance (A), the novolak resin (B), and the phenolic hydroxyl group-containing compound (C). The content of each component with respect to the total amount of (A) is 0.1 to 30% by weight of component (B), 30 to 99.4% by weight of component (B), and 0.5 to 40% by weight of component (C). Preferably, the component (A) is 0.5 to 20% by weight, the component (B) is 50 to 98.5% by weight, and the component (C) is 1 to 30% by weight. The component (1) is 1 to 12% by weight, the component (B) is 63 to 97% by weight, and the component (C) is particularly preferably 2 to 25% by weight.
[0057]
In addition, the positive photosensitive composition of the present invention may include, for example, Victoria Pure Blue (42595), Crystal Violet (42555), Crystal Violet Lactone, Auramin O (41000), Catillon Brilliant Flavin (Basic). 13), Rhodamine 6GCP (45160), Rhodamine B (45170), Safranin OK70: 100 (50240), Erioglaucine X (42080), Fast Black HB (26150), No. 13 120 / Lionol Yellow (21090), Lionol Yellow GRO (21090), Shimla First Yellow 8GF (21105), Benzidine Yellow 4T-564D (21095), Shimler First Red 4015 (12355), Lionol Red B4401 (15850), Coloring agents such as pigments or dyes such as Fast Gen Blue TGR-L (74160) and Lionol Blue SM (26150) may be contained. Here, the number in the parenthesis means a color index (CI).
[0058]
The content of the colorant in the positive photosensitive composition of the present invention is preferably 0 to 50% by weight, more preferably 0.5 to 30% by weight, and 1 to 20% by weight. Is particularly preferred.
[0059]
In addition to the above-mentioned components, the positive photosensitive composition of the present invention includes various commonly used additives such as a coatability improver, a developability improver, an adhesion improver, a sensitivity improver, and a sensitizer. The agent may further be contained in the range of preferably 10% by weight or less, more preferably 5% by weight or less.
[0060]
The positive photosensitive composition of the present invention is usually coated on the surface of the support as a solution in which each of the components is dissolved in an appropriate solvent, and then heated and dried to form a photosensitive composition layer on the surface of the support. A positive photosensitive lithographic printing plate on which is formed.
[0061]
Here, the solvent is not particularly limited as long as it has sufficient solubility with respect to the components used and gives good coating properties. For example, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve Cellosolve solvents such as acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monobutyl ether acetate, dipropylene glycol dimethyl ether, etc. Solvents, butyl acetate, amyl acetate, ethyl butyrate, butyl butyrate, diethyl oxalate, ethyl pyruvate, ethyl Ester solvents such as 2-hydroxybutyrate, ethyl acetoacetate, methyl lactate, ethyl lactate, methyl 3-methoxypropionate, alcohol solvents such as heptanol, hexanol, diacetone alcohol, furfuryl alcohol, cyclohexanone, methyl amyl ketone Ketone solvents such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone and the like, acetic acid, or a mixed solvent thereof, and those obtained by adding an aromatic hydrocarbon thereto. The use ratio of the solvent is usually in the range of about 1 to 20 times by weight with respect to the total amount of the photosensitive composition.
[0062]
As the coating method, conventionally known methods such as spin coating, wire bar coating, dip coating, air knife coating, roll coating, blade coating, and curtain coating can be used. The coating amount varies depending on the application, but the dry film thickness is usually in the range of 0.3 to 7 μm, preferably 0.5 to 5 μm, particularly preferably 1 to 3 μm. In addition, as drying temperature in that case, about 30-170 degreeC, for example, Preferably about 40-150 degreeC is taken.
[0063]
In order to make the effect of the present invention more reliable, for example, heating at a temperature of about 40 to 100 ° C., preferably about 40 to 70 ° C., for about 1 minute to 50 hours, preferably about 30 minutes to 20 hours. It is preferable to perform the treatment.
[0064]
In addition, as the support, a metal plate such as aluminum, zinc, copper, steel, etc., a metal plate plated or vapor-deposited with aluminum, zinc, copper, iron, chromium, nickel, paper, paper coated with resin, aluminum, etc. Paper, plastic film, hydrophilized plastic film, glass plate, and the like with a metal foil attached thereto. Among them, an aluminum plate is preferable, and surface treatment such as graining treatment by electrolytic etching or brush polishing in hydrochloric acid or nitric acid solution, anodizing treatment in sulfuric acid solution, and sealing treatment as necessary is performed. An applied aluminum plate is more preferable. As the roughness of the support surface, average roughness R _a as defined in JIS B0601, usually, 0.3 to 1.0 [mu] m, preferably about 0.4～0.8Myuemu.
[0065]
Examples of the light source for image exposure of the positive photosensitive composition layer in the present invention mainly include laser light sources such as HeNe laser, argon ion laser, YAG laser, HeCd laser, semiconductor laser, and ruby laser. In the case of forming an image with heat generated by absorbing light, a light source that generates a near infrared laser beam of 650 to 1300 nm is preferable, and examples thereof include solid lasers such as ruby laser, YAG laser, semiconductor laser, and LED. In particular, a small and long-life semiconductor laser or YAG laser is preferable. With these light sources, scanning exposure is usually performed, and then development is performed with a developer to form an image.
[0066]
The laser light source usually scans the surface of the photosensitive composition layer as a high-intensity light beam (beam) collected by a lens. The sensitivity characteristic (mJ) of the photosensitive composition layer according to the present invention is sensitive to the scanning. / cm ²⁾ may be dependent on the light intensity of the laser beam for receiving ^{(mJ / s · cm 2)} . Here, the light intensity of the laser beam is obtained by dividing the amount of energy (mJ / s) per unit time of the laser beam measured by an optical power meter by the irradiation area (cm ² ) of the laser beam on the surface of the photosensitive composition layer. Can be obtained. The irradiation area of the laser beam is usually defined by the area of the portion exceeding 1 / e ² intensity of the laser peak intensity, but can be measured by exposing a photosensitive composition exhibiting a reciprocity law in a simple manner. .
[0067]
In the present invention, the light intensity of the light source is preferably 2.0 × 10 ⁶ mJ / s · cm ² or more, and more preferably 1.0 × 10 ⁷ mJ / s · cm ² or more. When the light intensity is in the above range, the scanning exposure time that can improve the sensitivity characteristics of the positive photosensitive composition layer in the present invention can be shortened, which is a great practical advantage.
[0068]
Examples of the developer used for developing the positive photosensitive material obtained by image exposure of the positive photosensitive lithographic printing plate of the present invention include sodium silicate, potassium silicate, lithium silicate, ammonium silicate, sodium metasilicate, potassium metasilicate, Sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, dibasic sodium phosphate, tribasic sodium phosphate, dibasic ammonium phosphate, tribasic ammonium phosphate, sodium borate, potassium borate, ammonium borate Inorganic alkali salts such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, monobutylamine, monoethanolamine, diethanolamine, triethanol Triethanolamine, monoisopropanolamine, an alkali developer comprising an aqueous solution of about 0.1 to 5% by weight of an organic amine compound diisopropanolamine used. Among them, alkali metal silicates such as sodium silicate and potassium silicate which are inorganic alkali salts are preferable. In addition, surfactants, such as anionic surfactant, nonionic surfactant, and amphoteric surfactant, and organic solvents, such as alcohol, can be added to a developing solution as needed.
[0069]
The development is usually carried out by immersion development, spray development, brush development, ultrasonic development or the like, preferably at a temperature of about 10 to 50 ° C., particularly preferably about 15 to 45 ° C.
[0070]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
[0071]
Examples 1-12, Comparative Example 1
An aluminum plate (thickness 0.24 mm) was degreased in a 5% by weight sodium hydroxide aqueous solution at 60 ° C. for 1 minute, and then in a hydrochloric acid aqueous solution having a concentration of 0.5 mol / liter, a temperature of 25 ° C. The electrolytic etching treatment was performed under the conditions of a current density of 60 A / dm ² and a treatment time of 30 seconds. Next, desmutting treatment was carried out in a 5 wt% aqueous sodium hydroxide solution at 60 ° C for 10 seconds, and then in a 20 wt% sulfuric acid solution at a temperature of 20 ° C, a current density of 3 A / dm ² , and a treatment time of 1 minute. Anodizing treatment was performed. Further, hot water sealing treatment was performed with hot water at 80 ° C. for 20 seconds to produce an aluminum plate for a lithographic printing plate support.
[0072]
On the surface of the obtained aluminum plate support, 3 parts by weight of the indole dye shown in the specific example (II-9) as the component (A) and a mixture of phenol: m-cresol: p-cresol as the component (B) 100 parts by weight of a novolak resin (“SK-188” manufactured by Sumitomo Durez) having a weight average molecular weight of 9,400, which is a polycondensate of 50:30:20 mixed phenols and formaldehyde in a molar ratio. C) A coating solution prepared by dissolving 3 parts by weight of crystal violet lactone in 1000 parts by weight of methyl cellosolve with the amount shown in Table 1 as a component and the phenolic hydroxyl group-containing compound shown in Table 1 as a component using a wire bar, 85 after drying for 2 minutes at ° C., by stabilizing at 55 ° C., positive photosensitive lithographic having the positive photosensitive composition layer of Nurimakuryou 2.4 g / m ² To prepare a printing plate.
[0073]
The obtained positive photosensitive lithographic printing plate is attached to a rotating drum, and while rotating the drum, a semiconductor laser (Applied Techno) with a wavelength of 830 nm and an output of 40 mW is irradiated with a beam spot diameter of 25 μm under a yellow lamp. Then, it was scanned and exposed, and then immersed in an alkaline developer (6-fold diluted solution of “SDR-1” manufactured by Konica Corporation) at 28 ° C. for 30 seconds, washed with water and developed.
[0074]
Sensitivity was determined as an energy value (mJ / cm ² ) from the maximum number of rotations of the drum when the obtained positive image gave a width of 25 μm, and the sensitivity was evaluated according to the following criteria. The results are shown in Table 1.
[0075]
A: Energy value 100 mJ / cm ² or less B: energy value 100 mJ / cm ² exceeded, 120 mJ / cm ² or less C: energy value 120 mJ / cm ² exceeded, 140 mJ / cm ² or less D: energy value 140 mJ / cm ² exceeded, 160 mJ / Cm ² or less E: Energy value exceeds 160 mJ / cm ²
Further, with respect to the obtained positive image, the reflection density before and after development in the non-exposed portion was measured using a reflection densitometer (“RD-514” manufactured by Macbeth), and the surface of the support before the formation of the photosensitive composition layer was measured. The residual film ratio was determined from the ratio of the respective values obtained by subtracting the reflection density value, evaluated according to the following criteria, and the results are shown in Table 1.
[0077]
A: Remaining film ratio 0.95 or more B: Remaining film ratio 0.90 or more, less than 0.95 C: Remaining film ratio 0.80 or more, less than 0.90 D: Remaining film ratio 0.70 or more, 0.80 Less than E: Remaining film ratio less than 0.70
[Table 1]

[0079]
The positive photosensitive lithographic printing plate obtained above was subjected to light intensity irradiation of 400 lux of a white fluorescent lamp (36W white fluorescent lamp “Neolmi Super FLR40S-W / M / 36” manufactured by Mitsubishi Electric Corporation). When the same development treatment as described above was performed after leaving for 10 hours, there was no substantial film loss in any of the examples and comparative examples, and the handleability under a white fluorescent lamp was good.
[0080]
Examples 13 to 16, Comparative Example 2
4 parts by weight of the same indole dye as used in the previous example as the component (A) on the surface of the same aluminum plate support as used in the previous example, and 100 parts by weight of the same novolak resin as used in the previous example as the component (B). The above examples except that the amount of the phenolic hydroxyl group-containing compound shown in Table 2 as the component (C) and the coating solution in which 10 parts by weight of crystal violet lactone was dissolved in 1200 parts by weight of cyclohexanone were used. In the same manner as above, a positive photosensitive lithographic printing plate was prepared.
[0081]
With respect to the obtained positive photosensitive lithographic printing plate, 200 lines at 1 to 99% of various exposure energies were used using an exposure apparatus (Creo, “Trend Setter 3244T”) using a semiconductor laser with a wavelength of 830 nm as a light source. By exposing the halftone image to an image and then immersing it in an alkaline developer (8-fold diluted solution of “DP-4” manufactured by Fuji Photo Film Co., Ltd.) at 28 ° C. for 30 seconds, washing with water and developing, 1 to A printing plate in which a 99% halftone dot image was reproduced was prepared, and the sensitivity at that time was determined as an exposure energy amount reproduced by a 3% halftone dot. The results are shown in Table 2.
[0082]
[Table 2]

[0083]
【The invention's effect】
According to the present invention, it is not sensitive to light in the ultraviolet region, has excellent handleability under a white fluorescent lamp, is sensitive to light in the near infrared region, has sensitivity, and an image portion and a non-image portion. It is possible to provide a positive photosensitive composition and a positive photosensitive lithographic printing plate that are excellent in contrast and have a sufficient remaining film ratio in the image area.

Claims (3)

Without including a dissolution inhibitor, the following component (A), component (B) and component (C) are added to the total amount of these three components: (A) component 0.1 to 30% by weight, (B) component 30 to 99.4 Ri name contained in the content of the% by weight and component (C) 0.5 to 40 wt%, causing a difference in solubility between an exposed portion and an unexposed portion by a change other than a chemical change A positive photosensitive composition characterized by the above.
(A) a photothermal conversion material that absorbs light from an image exposure light source and converts it into heat (B) a novolac resin (C) a phenolic hydroxyl group-containing compound that is different from the phenols constituting the novolak resin of component (B) Molecular weight less than 1,500   The positive photosensitive composition according to claim 1, wherein the component (A) is a cyanine dye having near infrared absorption ability.   A positive photosensitive lithographic printing plate comprising a layer of the positive photosensitive composition according to claim 1 or 2 formed on a support surface.