JP2004118070A - Original plate for planographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative original plate for planographic printing plate which realizes direct recording from digital data of a computer, etc., by using a solid-state laser and a semiconductor laser radiating IR rays, and has high sensitivity and excellent developability. <P>SOLUTION: The original plate for the planographic printing plate is formed by successively disposing, on a support, a photosensitive layer which contains (A) an IR absorbent, (B) a radical generating agent, and (C) a radical polymerizable compound and induces a curing reaction by irradiation with IR rays and an overcoat layer of ≥0.05 to ≤1.0 g/m<SP>2</SP>in film weight when dried. <P>COPYRIGHT: (C)2004,JPO

Description

【００３０】
前記一般式（Ｉ）中、Ｘ^１は、ハロゲン原子、またはＸ^２−Ｌ^１を示す。ここで、Ｘ^２は酸素原子または、硫黄原子を示し、Ｌ^１は、炭素原子数１〜１２の炭化水素基を示す。Ｒ^１およびＲ^２は、それぞれ独立に、炭素原子数１〜１２の炭化水素基を示す。感光層塗布液の保存安定性から、Ｒ^１およびＲ^２は、炭素原子数２個以上の炭化水素基であることが好ましく、さらに、Ｒ^１とＲ^２とは互いに結合し、５員環または６員環を形成していることが特に好ましい。
【００３１】
Ａｒ^１、Ａｒ^２は、それぞれ同じでも異なっていても良く、置換基を有していても良い芳香族炭化水素基を示す。好ましい芳香族炭化水素基としては、ベンゼン環およびナフタレン環が挙げられる。また、好ましい置換基としては、炭素原子数１２個以下の炭化水素基、ハロゲン原子、炭素原子数１２個以下のアルコキシ基が挙げられる。Ｙ^１、Ｙ^２は、それぞれ同じでも異なっていても良く、硫黄原子または炭素原子数１２個以下のジアルキルメチレン基を示す。Ｒ^３、Ｒ^４は、それぞれ同じでも異なっていても良く、置換基を有していても良い炭素原子数２０個以下の炭化水素基を示す。好ましい置換基としては、炭素原子数１２個以下のアルコキシ基、カルボキシル基、スルホ基が挙げられる。Ｒ^５、Ｒ^６、Ｒ^７およびＲ^８は、それぞれ同じでも異なっていても良く、水素原子または炭素原子数１２個以下の炭化水素基を示す。原料の入手性から、好ましくは水素原子である。また、Ｚ^１−は、対アニオンを示す。ただし、Ｒ^１〜Ｒ^８のいずれかにスルホ基が置換されている場合は、Ｚ^１−は必要ない。好ましいＺ^１−は、感光層塗布液の保存安定性から、ハロゲンイオン、過塩素酸イオン、テトラフルオロボレートイオン、ヘキサフルオロホスフェートイオン、およびスルホン酸イオンであり、特に好ましくは、過塩素酸イオン、ヘキサフルオロフォスフェートイオン、およびアリールスルホン酸イオンである。
【００３２】
本発明において、好適に用いることのできる一般式（Ｉ）で示されるシアニン色素の具体例としては、特開２００１−１３３９６９号公報の段落番号［００１７］〜［００１９］に記載されたものを挙げることができる。
【００３３】
本発明において使用される顔料としては、市販の顔料及びカラーインデックス（Ｃ．Ｉ．）便覧、「最新顔料便覧」（日本顔料技術協会編、１９７７年刊）、「最新顔料応用技術」（ＣＭＣ出版、１９８６年刊）、「印刷インキ技術」ＣＭＣ出版、１９８４年刊）に記載されている顔料が利用できる。
顔料の種類としては、黒色顔料、黄色顔料、オレンジ色顔料、褐色顔料、赤色顔料、紫色顔料、青色顔料、緑色顔料、蛍光顔料、金属粉顔料、その他、ポリマー結合色素が挙げられる。具体的には、不溶性アゾ顔料、アゾレーキ顔料、縮合アゾ顔料、キレートアゾ顔料、フタロシアニン系顔料、アントラキノン系顔料、ペリレン及びペリノン系顔料、チオインジゴ系顔料、キナクリドン系顔料、ジオキサジン系顔料、イソインドリノン系顔料、キノフタロン系顔料、染付けレーキ顔料、アジン顔料、ニトロソ顔料、ニトロ顔料、天然顔料、蛍光顔料、無機顔料、カーボンブラック等が使用できる。これらの顔料のうち好ましいものはカーボンブラックである。
【００３４】
これら顔料は表面処理をせずに用いてもよく、表面処理を施して用いてもよい。表面処理の方法には、樹脂やワックスを表面コートする方法、界面活性剤を付着させる方法、反応性物質（例えば、シランカップリング剤、エポキシ化合物、ポリイソシアネート等）を顔料表面に結合させる方法等が考えられる。上記の表面処理方法は、「金属石鹸の性質と応用」（幸書房）、「印刷インキ技術」（ＣＭＣ出版、１９８４年刊）及び「最新顔料応用技術」（ＣＭＣ出版、１９８６年刊）に記載されている。
【００３５】
顔料の粒径は０．０１μｍ〜１０μｍの範囲にあることが好ましく、０．０５μｍ〜１μｍの範囲にあることがさらに好ましく、特に０．１μｍ〜１μｍの範囲にあることが好ましい。顔料の粒径が０．０１μｍ未満のときは分散物の感光層塗布液中での安定性の点で好ましくなく、また、１０μｍを越えると感光層の均一性の点で好ましくない。
【００３６】
顔料を分散する方法としては、インク製造やトナー製造等に用いられる公知の分散技術が使用できる。分散機としては、超音波分散器、サンドミル、アトライター、パールミル、スーパーミル、ボールミル、インペラー、デスパーザー、ＫＤミル、コロイドミル、ダイナトロン、３本ロールミル、加圧ニーダー等が挙げられる。詳細は、「最新顔料応用技術」（ＣＭＣ出版、１９８６年刊）に記載されている。
【００３７】
これらの赤外線吸収剤の添加量は、本発明における感光層の、波長７６０ｎｍ〜１２００ｎｍの範囲における吸収極大での光学濃度が、０．１〜３．０の範囲となるようにすることが好ましい。この範囲をはずれた場合、感度が低くなる傾向がある。光学濃度は前記赤外線吸収剤の添加量と感光層の厚みとにより決定されるため、所定の光学濃度は両者の条件を制御することにより得られる。感光層の光学濃度は常法により測定することができる。測定方法としては、例えば、透明、或いは白色の支持体上に、乾燥後の塗布量が平版印刷版として必要な範囲において適宜決定された厚みの感光層を形成し、透過型の光学濃度計で測定する方法、アルミニウム等の反射性の支持体上に感光層を形成し、反射濃度を測定する方法等が挙げられる。
【００３８】
［（Ｂ）ラジカル発生剤］
本発明において用いられるラジカル発生剤は、（Ａ）赤外線吸収剤と組み合わせて用い、赤外線レーザーを照射した際にラジカルを発生する化合物を指す。ラジカル発生剤としては、オニウム塩、トリハロメチル基を有するトリアジン化合物、過酸化物、アゾ系重合開始剤、アジド化合物、キノンジアジド、ボレート化合物などが挙げられるが、オニウム塩が高感度であり、好ましい。本発明においてラジカル重合開始剤として好適に用い得るオニウム塩について説明する。好ましいオニウム塩としては、ヨードニウム塩、ジアゾニウム塩、スルホニウム塩が挙げられる。本発明において、これらのオニウム塩は酸発生剤ではなく、ラジカル重合の開始剤として機能する。本発明において好適に用いられるオニウム塩は、下記一般式（ＩＩ）〜（ＩＶ）で表されるオニウム塩である。
【００３９】
【化２】

【００４０】
式（ＩＩ）中、Ａｒ^１１とＡｒ^１２は、それぞれ独立に、置換基を有していても良い炭素原子数２０個以下のアリール基を示す。このアリール基が置換基を有する場合の好ましい置換基としては、ハロゲン原子、ニトロ基、炭素原子数１２個以下のアルキル基、炭素原子数１２個以下のアルコキシ基、又は炭素原子数１２個以下のアリールオキシ基が挙げられる。Ｚ^１１−はハロゲンイオン、過塩素酸イオン、テトラフルオロボレートイオン、ヘキサフルオロホスフェートイオン、カルボキシレートイオン、及びスルホン酸イオンからなる群より選択される対イオンを表し、好ましくは、過塩素酸イオン、ヘキサフルオロフォスフェートイオン、カルボキシレートイオン、及びアリールスルホン酸イオンである。
【００４１】
式（ＩＩＩ）中、Ａｒ^２１は、置換基を有していても良い炭素原子数２０個以下のアリール基を示す。好ましい置換基としては、ハロゲン原子、ニトロ基、炭素原子数１２個以下のアルキル基、炭素原子数１２個以下のアルコキシ基、炭素原子数１２個以下のアリールオキシ基、炭素原子数１２個以下のアルキルアミノ基、炭素原子数１２個以下のジアルキルアミノ基、炭素原子数１２個以下のアリールアミノ基又は、炭素原子数１２個以下のジアリールアミノ基が挙げられる。Ｚ^２１−はＺ^１１−と同義の対イオンを表す。
【００４２】
式（ＩＶ）中、Ｒ^３１、Ｒ^３２及びＲ^３３は、それぞれ同じでも異なっていても良く、置換基を有していても良い炭素原子数２０個以下の炭化水素基を示す。好ましい置換基としては、ハロゲン原子、ニトロ基、炭素原子数１２個以下のアルキル基、炭素原子数１２個以下のアルコキシ基、又は炭素原子数１２個以下のアリールオキシ基が挙げられる。Ｚ^３１−はＺ^１１−と同義の対イオンを表す。
【００４３】
本発明において、ラジカル発生剤として好適に用いることのできるオニウム塩の具体例としては、特開２００１−１３３９６９号公報の段落番号［００３０］〜［００３３］に記載されたものを挙げることができる。
【００４４】
本発明において用いられるラジカル発生剤は、極大吸収波長が４００ｎｍ以下であることが好ましく、さらに３６０ｎｍ以下であることが好ましい。このように吸収波長を紫外線領域にすることにより、平版印刷版原版の取り扱いを白灯下で実施することができる。
【００４５】
これらのラジカル発生剤は、感光層塗布液の全固形分に対し０．１〜５０質量％、好ましくは０．５〜３０質量％、特に好ましくは１〜２０質量％の割合で感光層塗布液中に添加することができる。添加量が０．１質量％未満であると感度が低くなり、また５０質量％を越えると印刷時非画像部に汚れが発生する。これらのラジカル発生剤は、１種のみを用いても良いし、２種以上を併用しても良い。また、これらのラジカル発生剤は他の成分と同一の層に添加してもよいし、別の層を設けそこへ添加してもよい。
【００４６】
［（Ｃ）ラジカル重合性化合物］
本発明に使用されるラジカル重合性化合物は、少なくとも一個のエチレン性不飽和二重結合を有するラジカル重合性化合物であり、末端エチレン性不飽和結合を少なくとも１個、好ましくは２個以上有する化合物から選ばれる。この様な化合物群は当該産業分野において広く知られるものであり、本発明においてはこれらを特に限定無く用いる事ができる。これらは、例えばモノマー、プレポリマー、すなわち２量体、３量体およびオリゴマー、またはそれらの混合物ならびにそれらの共重合体などの化学的形態をもつ。モノマーおよびその共重合体の例としては、不飽和カルボン酸（例えば、アクリル酸、メタクリル酸、イタコン酸、クロトン酸、イソクロトン酸、マレイン酸など）や、そのエステル類、アミド類があげられ、好ましくは、不飽和カルボン酸と脂肪族多価アルコール化合物とのエステル、不飽和カルボン酸と脂肪族多価アミン化合物とのアミド類が用いられる。また、ヒドロキシル基や、アミノ基、メルカプト基等の求核性置換基を有する不飽和カルボン酸エステル、アミド類と単官能もしくは多官能イソシアネート類、エポキシ類との付加反応物、単官能もしくは、多官能のカルボン酸との脱水縮合反応物等も好適に使用される。また、イソシアナート基やエポキシ基等の親電子性置換基を有する不飽和カルボン酸エステルまたはアミド類と、単官能もしくは多官能のアルコール類、アミン類およびチオール類との付加反応物、さらに、ハロゲン基やトシルオキシ基等の脱離性置換基を有する不飽和カルボン酸エステルまたはアミド類と、単官能もしくは多官能のアルコール類、アミン類およびチオール類との置換反応物も好適である。また、別の例として、上記の不飽和カルボン酸の代わりに、不飽和ホスホン酸、スチレン等に置き換えた化合物群を使用する事も可能である。
【００４７】
脂肪族多価アルコール化合物と不飽和カルボン酸とのエステルであるラジカル重合性化合物であるアクリル酸エステル、メタクリル酸エステル、イタコン酸エステル、クロトン酸エステル、イソクロトン酸エステル、マレイン酸エステルの具体例は、特開２００１−１３３９６９号公報の段落番号［００３７］〜［００４２］に記載されており、これらを本発明にも適用することができる。
【００４８】
その他のエステルの例として、例えば、特公昭４６−２７９２６、特公昭５１−４７３３４、特開昭５７−１９６２３１記載の脂肪族アルコール系エステル類や、特開昭５９−５２４０、特開昭５９−５２４１、特開平２−２２６１４９記載の芳香族系骨格を有するもの、特開平１−１６５６１３記載のアミノ基を含有するもの等も好適に用いられる。
【００４９】
また、脂肪族多価アミン化合物と不飽和カルボン酸とのアミドのモノマーの具体例としては、メチレンビス−アクリルアミド、メチレンビス−メタクリルアミド、１，６−ヘキサメチレンビス−アクリルアミド、１，６−ヘキサメチレンビス−メタクリルアミド、ジエチレントリアミントリスアクリルアミド、キシリレンビスアクリルアミド、キシリレンビスメタクリルアミド等がある。
その他の好ましいアミド系モノマーの例としては、特公昭５４−２１７２６記載のシクロへキシレン構造を有すものをあげる事ができる。
【００５０】
また、イソシアネートと水酸基の付加反応を用いて製造されるウレタン系付加重合性化合物も好適であり、そのような具体例としては、例えば、特公昭４８−４１７０８号公報中に記載されている１分子に２個以上のイソシアネート基を有するポリイソシアネート化合物に、下記式（Ｖ）で示される水酸基を含有するビニルモノマーを付加させた１分子中に２個以上の重合性ビニル基を含有するビニルウレタン化合物等が挙げられる。
【００５１】
一般式（Ｖ）
ＣＨ_２＝Ｃ（Ｒ^４１）ＣＯＯＣＨ_２ＣＨ（Ｒ^４２）ＯＨ
（ただし、Ｒ^４１及びＲ^４２は、Ｈ又はＣＨ_３を示す。）
【００５２】
また、特開昭５１−３７１９３号、特公平２−３２２９３号、特公平２−１６７６５号に記載されているようなウレタンアクリレート類や、特公昭５８−４９８６０号、特公昭５６−１７６５４号、特公昭６２−３９４１７、特公昭６２−３９４１８号記載のエチレンオキサイド系骨格を有するウレタン化合物類も好適である。
【００５３】
さらに、特開昭６３−２７７６５３，特開昭６３−２６０９０９号、特開平１−１０５２３８号に記載される、分子内にアミノ構造やスルフィド構造を有するラジカル重合性化合物類を用いても良い。
【００５４】
その他の例としては、特開昭４８−６４１８３号、特公昭４９−４３１９１号、特公昭５２−３０４９０号、各公報に記載されているようなポリエステルアクリレート類、エポキシ樹脂と（メタ）アクリル酸を反応させたエポキシアクリレート類等の多官能のアクリレートやメタクリレートをあげることができる。また、特公昭４６−４３９４６号、特公平１−４０３３７号、特公平１−４０３３６号記載の特定の不飽和化合物や、特開平２−２５４９３号記載のビニルホスホン酸系化合物等もあげることができる。また、ある場合には、特開昭６１−２２０４８号記載のペルフルオロアルキル基を含有する構造が好適に使用される。さらに日本接着協会誌ｖｏｌ．２０、Ｎｏ．７、３００〜３０８ページ（１９８４年）に光硬化性モノマーおよびオリゴマーとして紹介されているものも使用することができる。
【００５５】
これらのラジカル重合性化合物について、どの様な構造を用いるか、単独で使用するか併用するか、添加量はどうかといった、使用方法の詳細は、最終的な記録材料の性能設計にあわせて、任意に設定できる。例えば、次のような観点から選択される。感度の点では１分子あたりの不飽和基含量が多い構造が好ましく、多くの場合、２官能以上がこのましい。また、画像部すなわち硬化膜の強度を高くするためには、３官能以上のものが良く、さらに、異なる官能数・異なる重合性基を有する化合物（例えば、アクリル酸エステル系化合物、メタクリル酸エステル系化合物、スチレン系化合物等）を組み合わせて用いることで、感光性と強度の両方を調節する方法も有効である。
大きな分子量の化合物や、疎水性の高い化合物は感度や膜強度に優れる反面、現像スピードや現像液中での析出といった点で好ましく無い場合がある。また、感光層中の他の成分（例えばバインダーポリマー、開始剤、着色剤等）との相溶性、分散性に対しても、ラジカル重合化合物の選択・使用法は重要な要因であり、例えば、低純度化合物の使用や、２種以上化合物の併用によって、相溶性を向上させうることがある。また、支持体、オーバーコート層等の密着性を向上せしめる目的で特定の構造を選択することもあり得る。感光層中のラジカル重合性化合物の配合比に関しては、多い方が感度的に有利であるが、多すぎる場合には、好ましく無い相分離が生じたり、感光層の粘着性による製造工程上の問題（例えば、感光層成分の転写、粘着に由来する製造不良）や、現像液からの析出が生じる等の問題を生じうる。これらの観点から、ラジカル重合性化合物の好ましい配合比は、多くの場合、組成物全成分に対して５〜８０質量％、好ましくは２０〜７５質量％である。また、これらは単独で用いても２種以上併用してもよい。そのほか、ラジカル重合性化合物の使用法は、酸素に対する重合阻害の大小、解像度、かぶり性、屈折率変化、表面粘着性等の観点から適切な構造、配合、添加量を任意に選択でき、さらに場合によっては下塗り、上塗りといった層構成・塗布方法も実施しうる。
【００５６】
［（Ｄ）バインダーポリマー］
本発明においては、膜強度向上の観点から、感光層にはさらにバインダーポリマーを使用することが好ましく、バインダーとしては線状有機ポリマーを用いることが好ましい。このような「線状有機ポリマー」としては、公知のものを任意に使用できる。好ましくは水現像あるいは弱アルカリ水現像を可能とするために、水あるいは弱アルカリ水可溶性または膨潤性である線状有機ポリマーが選択される。線状有機ポリマーは、感光層を形成するための皮膜形成剤としてだけでなく、水、弱アルカリ水あるいは有機溶剤現像剤としての用途に応じて選択使用される。例えば、水可溶性有機ポリマーを用いると水現像が可能になる。このような線状有機ポリマーとしては、側鎖にカルボン酸基を有するラジカル重合体、例えば特開昭５９−４４６１５号、特公昭５４−３４３２７号、特公昭５８−１２５７７号、特公昭５４−２５９５７号、特開昭５４−９２７２３号、特開昭５９−５３８３６号、特開昭５９−７１０４８号に記載されているもの、すなわち、メタクリル酸共重合体、アクリル酸共重合体、イタコン酸共重合体、クロトン酸共重合体、マレイン酸共重合体、部分エステル化マレイン酸共重合体等がある。また同様に側鎖にカルボン酸基を有する酸性セルロース誘導体がある。この他に水酸基を有する重合体に環状酸無水物を付加させたものなどが有用である。
【００５７】
特にこれらの中でも、アリル基、（メタ）アクリロイル基、（メタ）アクリルアミド基等のエチレン性不飽和二重結合と、カルボキシル基とを側鎖に有する樹脂が、膜強度、感度、現像性のバランスに優れており、好適である。
【００５８】
また、特公平７−１２００４０号、特公平７−１２００４１号、特公平７−１２００４２号、特公平８−１２４２４号、特開昭６３−２８７９４４号、特開昭６３−２８７９４７号、特開平１−２７１７４１号、特開平１１−３５２６９１号等に記載される酸基を含有するウレタン系バインダーポリマーは、非常に、強度に優れるので、耐刷性・低露光適性の点で有利である。
【００５９】
さらにこの他に水溶性線状有機ポリマーとして、ポリビニルピロリドンやポリエチレンオキサイド等が有用である。また硬化皮膜の強度を上げるためにアルコール可溶性ナイロンや２，２−ビス−（４−ヒドロキシフェニル）−プロパンとエピクロロヒドリンのポリエーテル等も有用である。
【００６０】
本発明で使用されるポリマーの質量平均分子量については好ましくは５０００以上であり、さらに好ましくは１万〜３０万の範囲であり、数平均分子量については好ましくは１０００以上であり、さらに好ましくは２０００〜２５万の範囲である。多分散度（重量平均分子量／数平均分子量）は１以上が好ましく、さらに好ましくは１．１〜１０の範囲である。
【００６１】
これらのポリマーは、ランダムポリマー、ブロックポリマー、グラフトポリマー等いずれでもよいが、ランダムポリマーであることが好ましい。
【００６２】
本発明で使用されるポリマーは従来公知の方法により合成できる。合成する際に用いられる溶媒としては、例えば、テトラヒドロフラン、エチレンジクロリド、シクロヘキサノン、メチルエチルケトン、アセトン、メタノール、エタノール、エチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、２−メトキシエチルアセテート、ジエチレングリコールジメチルエーテル、１−メトキシ−２−プロパノール、１−メトキシ−２−プロピルアセテート、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミド、トルエン、酢酸エチル、乳酸メチル、乳酸エチル、ジメチルスルホキシド、水等が挙げられる。これらの溶媒は単独で又は２種以上混合して用いられる。
【００６３】
本発明で使用されるポリマーを合成する際に用いられるラジカル重合開始剤としては、アゾ系開始剤、過酸化物開始剤等公知の化合物が使用できる。
【００６４】
本発明で使用されるバインダーポリマーは単独で用いても混合して用いてもよい。これらポリマーは、感光層塗布液の全固形分に対し２０〜９５質量％、好ましくは３０〜９０質量％の割合で感光層中に添加される。添加量が２０質量％未満の場合は、画像形成した際、画像部の強度が不足する。また添加量が９５質量％を越える場合は、画像形成されない。またラジカル重合可能なエチレン性不飽和二重結合を有する化合物と線状有機ポリマーは、質量比で１／９〜７／３の範囲とするのが好ましい。
【００６５】
［その他の成分］
本発明の平版印刷版原版の感光層には、前記の膜硬化に関する成分のみならず、平版印刷版原版としての特性やハンドリング性などを改良するため、さらに必要に応じて種々の化合物を添加してもよい。
例えば、可視光域に大きな吸収を持つ染料を画像の着色剤として使用することができる。具体的には、オイルイエロー＃１０１、オイルイエロー＃１０３、オイルピンク＃３１２、オイルグリーンＢＧ、オイルブルーＢＯＳ、オイルブルー＃６０３、オイルブラックＢＹ、オイルブラックＢＳ、オイルブラックＴ−５０５（以上オリエント化学工業（株）製）、ビクトリアピュアブルー、クリスタルバイオレット（ＣＩ４２５５５）、メチルバイオレット（ＣＩ４２５３５）、エチルバイオレット、ローダミンＢ（ＣＩ１４５１７０Ｂ）、マラカイトグリーン（ＣＩ４２０００）、メチレンブルー（ＣＩ５２０１５）等、及び特開昭６２−２９３２４７号に記載されている染料を挙げることができる。また、フタロシアニン系顔料、アゾ系顔料、カーボンブラック、酸化チタンなどの顔料も好適に用いることができる。
【００６６】
これらの着色剤は、画像形成後、画像部と非画像部の区別がつきやすいので、添加する方が好ましい。なお、添加量は、感光層塗布液全固形分に対し、０．０１〜１０質量％の割合である。
【００６７】
また、本発明においては、感光層塗布液の調製中あるいは保存中においてラジカル重合可能なエチレン性不飽和二重結合を有する化合物の不要な熱重合を阻止するために少量の熱重合防止剤を添加することが望ましい。適当な熱重合防止剤としてはハイドロキノン、ｐ−メトキシフェノール、ジ−ｔ−ブチル−ｐ−クレゾール、ピロガロール、ｔ−ブチルカテコール、ベンゾキノン、４，４’−チオビス（３−メチル−６−ｔ−ブチルフェノール）、２，２’−メチレンビス（４−メチル−６−ｔ−ブチルフェノール）、Ｎ−ニトロソ−Ｎ−フェニルヒドロキシルアミンアルミニウム塩等が挙げられる。熱重合防止剤の添加量は、全組成物の質量に対して約０．０１質量％〜約５質量％が好ましい。また必要に応じて、酸素による重合阻害を防止するためにベヘン酸やベヘン酸アミドのような高級脂肪酸誘導体等を添加して、塗布後の乾燥の過程で感光層の表面に偏在させてもよい。高級脂肪酸誘導体の添加量は、全組成物の約０．１質量％〜約１０質量％が好ましい。
【００６８】
また、感光層塗布液中には、現像条件に対する処理の安定性を広げるため、特開昭６２−２５１７４０号や特開平３−２０８５１４号に記載されているような非イオン界面活性剤、特開昭５９−１２１０４４号、特開平４−１３１４９号に記載されているような両性界面活性剤を添加することができる。
【００６９】
非イオン界面活性剤の具体例としては、ソルビタントリステアレート、ソルビタンモノパルミテート、ソルビタントリオレート、ステアリン酸モノグリセリド、ポリオキシエチレンノニルフェニルエーテル等が挙げられる。
【００７０】
両性界面活性剤の具体例としては、アルキルジ（アミノエチル）グリシン、アルキルポリアミノエチルグリシン塩酸塩、２−アルキル−Ｎ−カルボキシエチル−Ｎ−ヒドロキシエチルイミダゾリニウムベタイン、Ｎ−テトラデシル−Ｎ，Ｎ−ベタイン型（例えば、商品名アモーゲンＫ、第一工業（株）製）等が挙げられる。
【００７１】
上記非イオン界面活性剤及び両性界面活性剤の感光層塗布液中に占める割合は、０．０５〜１５質量％が好ましく、より好ましくは０．１〜５質量％である。その他、目的に応じて密着向上剤、現像改良剤、紫外線吸収剤、スベリ剤等の添加剤を好適に配合することができる。
【００７２】
さらに、本発明に係る感光層塗布液中には、必要に応じ、塗膜の柔軟性等を付与するために可塑剤が加えられる。例えば、ポリエチレングリコール、クエン酸トリブチル、フタル酸ジエチル、フタル酸ジブチル、フタル酸ジヘキシル、フタル酸ジオクチル、リン酸トリクレジル、リン酸トリブチル、リン酸トリオクチル、オレイン酸テトラヒドロフルフリル等が用いられる。
【００７３】
本発明の平版印刷版原版を製造するには、通常、感光層塗布液に必要な上記各成分を溶媒に溶かして、適当な支持体上に塗布すればよい。ここで使用する溶媒としては、エチレンジクロライド、シクロヘキサノン、メチルエチルケトン、メタノール、エタノール、プロパノール、エチレングリコールモノメチルエーテル、１−メトキシ−２−プロパノール、２−メトキシエチルアセテート、１−メトキシ−２−プロピルアセテート、ジメトキシエタン、乳酸メチル、乳酸エチル、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ，Ｎ−ジメチルホルムアミド、テトラメチルウレア、Ｎ−メチルピロリドン、ジメチルスルホキシド、スルホラン、γ−ブチルラクトン、トルエン、水等を挙げることができるがこれに限定されるものではない。これらの溶媒は単独又は混合して使用される。溶媒中の上記成分（添加剤を含む全固形分）の濃度は、好ましくは１〜５０質量％である。
【００７４】
また塗布、乾燥後に得られる支持体上の感光層塗布量（固形分）は、用途によって異なるが、平版印刷版原版についていえば一般的に０．５〜５．０ｇ／ｍ^２が好ましい。塗布量が少なくなるにつれて、見かけの感度は大になるが、画像記録の機能を果たす感光層の皮膜特性は低下する。
塗布する方法としては、種々の方法を用いることができるが、例えば、バーコーター塗布、回転塗布、スプレー塗布、カーテン塗布、ディップ塗布、エアーナイフ塗布、ブレード塗布、ロール塗布等を挙げることができる。
【００７５】
本発明に係る感光層塗布液には、塗布性を良化するための界面活性剤、例えば、特開昭６２−１７０９５０号に記載されているようなフッ素系界面活性剤を添加することができる。好ましい添加量は、全感光層の材料固形分中０．０１〜１質量％、さらに好ましくは０．０５〜０．５質量％である。
【００７６】
［支持体］
本発明の平版印刷版原版に用い得る支持体としては、寸度的に安定な板状物であれば特に制限はなく、例えば、紙、プラスチック（例えば、ポリエチレン、ポリプロピレン、ポリスチレン等）がラミネートされた紙、金属板（例えば、アルミニウム、亜鉛、銅等）、プラスチックフィルム（例えば、二酢酸セルロース、三酢酸セルロース、プロピオン酸セルロース、酪酸セルロース、酢酸酪酸セルロース、硝酸セルロース、ポリエチレンテレフタレート、ポリエチレン、ポリスチレン、ポリプロピレン、ポリカーボネート、ポリビニルアセタール等）、上記の如き金属がラミネート若しくは蒸着された紙又はプラスチックフィルム等を挙げることができる。
【００７７】
本発明で使用する支持体としては、軽量で表面処理性、加工性、耐食性に優れたアルミニウム板を使用することが好ましい。この目的に供されるアルミニウム材質としては、ＪＩＳ　１０５０材、ＪＩＳ　１１００材、ＪＩＳ　１０７０材、Ａｌ−Ｍｇ系合金、Ａｌ−Ｍｎ系合金、Ａｌ−Ｍｎ−Ｍｇ系合金、Ａｌ−Ｚｒ系合金。Ａｌ−Ｍｇ−Ｓｉ系合金などが挙げられる。
【００７８】
好適なアルミニウム板は、純アルミニウム板およびアルミニウムを主成分とし、微量の異元素を含む前記の如き合金板であり、更にアルミニウムがラミネートもしくは蒸着されたプラスチックフィルムでもよい。アルミニウム合金に含まれる異元素には、ケイ素、鉄、マンガン、銅、マグネシウム、クロム、亜鉛、ビスマス、ニッケル、チタンなどがある。合金中の異元素の含有量は１０質量％以下である。アルミニウム板としては、純アルミニウムが好ましいが、完全に純粋なアルミニウムは精錬技術上製造が困難であるので、僅かに異元素を含有するものでもよい。このように、アルミニウム板は、その組成が特定されるものではなく、従来より公知公用の素材のアルミニウム板を適宜に利用することができる。前記アルミニウム板の厚みとしては、およそ０．１〜０．６ｍｍ程度が好ましく、０．１５〜０．４ｍｍがより好ましく、０．２〜０．３ｍｍが特に好ましい。
【００７９】
前記アルミニウム板を粗面化するに先立ち、所望により、表面の圧延油を除去するための例えば界面活性剤、有機溶剤またはアルカリ性水溶液などによる脱脂処理が行われる。アルミニウム板の表面の粗面化処理は、種々の方法により行われるが、例えば、機械的に粗面化する方法、電気化学的に表面を溶解粗面化する方法および化学的に表面を選択溶解させる方法により行われる。機械的方法としては、ボール研磨法、ブラシ研磨法、ブラスト研磨法、バフ研磨法などの公知の方法を用いることができる。また、電気化学的な粗面化法としては塩酸または硝酸電解液中で交流または直流により行う方法がある。
【００８０】
このように粗面化されたアルミニウム板は、必要に応じてアルカリエッチング処理および中和処理された後、所望により表面の保水性や耐摩耗性を高めるために陽極酸化処理が施される。陽極酸化による、陽極酸化皮膜の量は、１．０ｇ／ｍ^２以上が好ましい。陽極酸化皮膜の量が、１．０ｇ／ｍ^２未満の場合には、耐刷性が不十分であったり、平版印刷版として用いた場合には、非画像部に傷が付き易くなって、印刷時に傷の部分にインキが付着するいわゆる「傷汚れ」が生じ易くなることがある。前記陽極酸化処理を施された後、前記アルミニウムの表面は、必要に応じて親水化処理が施される。
【００８１】
また、このようなアルミニウム支持体は陽極酸化処理後に有機酸またはその塩による処理または、感光層塗布の下塗り層を適用して用いることができる。
【００８２】
なお支持体と感光層との密着性を高めるための中間層を設けてもよい。密着性の向上のためには、一般に中間層は、ジアゾ樹脂や、例えばアルミニウムに吸着するリン酸化合物等からなっている。中間層の厚さは任意であり、露光した時に、上層の感光層と均一な結合形成反応を行い得る厚みでなければならない。通常、乾燥固体で約１〜１００ｍｇ／ｍ^２の塗布割合がよく、５〜４０ｍｇ／ｍ^２が特に良好である。中間層中におけるジアゾ樹脂の使用割合は、３０〜１００％、好ましくは６０〜１００％である。
【００８３】
支持体表面に以上のような処理或いは、下塗りなどが施された後、支持体の裏面には、必要に応じてバックコートが設けられる。かかるバックコートとしては特開平５−４５８８５号公報記載の有機高分子化合物および特開平６−３５１７４号記載の有機または無機金属化合物を加水分解および重縮合させて得られる金属酸化物からなる被覆層が好ましく用いられる。
【００８４】
平版印刷版用支持体として好ましい特性としては、中心線平均粗さで０．１０〜１．２μｍである。０．１０μｍより低いと感光層と密着性が低下し、著しい耐刷の低下を生じてしまう。１．２μｍより大きい場合、印刷時の汚れ性が悪化してしまう。さらに支持体の色濃度としては、反射濃度値として０．１５〜０．６５であり、０．１５より白い場合、画像露光時のハレーションが強すぎ画像形成に支障をきたしてしまい、０．６５より黒い場合、現像後の検版作業において画像が見難くく、著しく検版性が悪いものとなってしまう。
【００８５】
以上のようにして、所定の処理を行って得られた支持体上に、先に述べた感光層、及び表面保護層、さらには、中間層、バックコート層等の他の任意の層を形成することで、本発明の平版印刷版原版を得ることができる。
本発明の平版印刷版原版は、赤外線レーザにより画像記録を行われる。本発明においては、波長７６０ｎｍから１２００ｎｍの赤外線を放射する固体レーザ及び半導体レーザにより画像露光されることが好ましい。レーザの出力は１００ｍＷ以上が好ましく、露光時間を短縮するため、マルチビームレーザデバイスを用いることが好ましい。また、１画素あたりの露光時間は２０μ秒以内であることが好ましい。記録材料に照射されるエネルギーは１０〜３００ｍＪ／ｃｍ^２であることが好ましい。露光のエネルギーが低すぎると感光層の硬化が十分に進行しなかったり、また、露光のエネルギーが高すぎると感光層がレーザーアブレーションされ、画像が損傷したりすることがある。
【００８６】
本発明における露光は光源の光ビームをオーバーラップさせて露光する。オーバーラップとは副走査ピッチ幅がビーム径より小さいことをいう。オーバーラップは、例えばビーム径をビーム強度の半値幅（ＦＷＨＭ）で表わしたとき、ＦＷＨＭ／副走査ピッチ幅（オーバーラップ係数）で定量的に表現することができる。本発明ではこのオーバーラップ係数が０．１以上であることが好ましい。
【００８７】
本発明に使用する露光装置の光源の走査方式は特に限定はなく、円筒外面走査方式、円筒内面走査方式、平面走査方式などを用いることができる。また、光源のチャンネルは単チャンネルでもマルチチャンネルでもよいが、円筒外面方式の場合にはマルチチャンネルが好ましく用いられる。
【００８８】
本発明の平版印刷版原版の現像、製版に用いられる現像液及び補充液としては従来より知られているアルカリ水溶液が使用できる。
例えば、ケイ酸ナトリウム、同カリウム、第３リン酸ナトリウム、同カリウム、同アンモニウム、第２リン酸ナトリウム、同カリウム、同アンモニウム、炭酸ナトリウム、同カリウム、同アンモニウム、炭酸水素ナトリウム、同カリウム、同アンモニウム、ほう酸ナトリウム、同カリウム、同アンモニウム、水酸化ナトリウム、同アンモニウム、同カリウム及び同リチウムなどの無機アルカリ塩が挙げられる。また、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、トリイソプロピルアミン、ｎ−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、エチレンイミン、エチレンジアミン、ピリジンなどの有機アルカリ剤も用いられる。これらのアルカリ剤は単独もしくは２種以上を組み合わせて用いられる。
【００８９】
これらのアルカリ剤の中で特に好ましい現像液は、ケイ酸ナトリウム、ケイ酸カリウム等のケイ酸塩水溶液である。その理由はケイ酸塩の成分である酸化珪素ＳｉＯ_２とアルカリ金属酸化物Ｍ_２Ｏの比率と濃度によって現像性の調節が可能となるためであり、例えば、特開昭５４−６２００４号公報、特公昭５７−７４２７号公報に記載されているようなアルカリ金属ケイ酸塩が有効に用いられる。
【００９０】
自動現像機を用いて現像する場合には、現像液よりもアルカリ強度の高い水溶液（補充液）を現像液に加えることによって、長時間現像タンク中の現像液を交換する事なく、多量のＰＳ版を処理できることが知られている。本発明においてもこの補充方式が好ましく適用される。現像液及び補充液には現像性の促進や抑制、現像カスの分散及び印刷版画像部の親インキ性を高める目的で必要に応じて種々の界面活性剤や有機溶剤を添加できる。
【００９１】
好ましい界面活性剤としては、アニオン系、カチオン系、ノニオン系及び両性界面活性剤があげられる。更に現像液及び補充液には必要に応じて、ハイドロキノン、レゾルシン、亜硫酸、亜硫酸水素酸などの無機酸のナトリウム塩、カリウム塩等の還元剤、更に有機カルボン酸、消泡剤、硬水軟化剤を加えることもできる。
【００９２】
上記現像液及び補充液を用いて現像処理された平版印刷版は水洗水、界面活性剤等を含有するリンス液、アラビアガムや澱粉誘導体を含む不感脂化液で後処理される。本発明の平版印刷版原版を上記方法により製版した印刷版を使用する場合の後処理としては、これらの処理を種々組み合わせて用いることができる。
【００９３】
近年、製版・印刷業界では製版作業の合理化および標準化のため、印刷版用の自動現像機が広く用いられている。本発明により得られた平版印刷版も、この自動現像機にて処理を施すことができるものである。この自動現像機は一般に現像部と後処理部からなり、印刷用版材を搬送する装置と各処理液槽とスプレー装置とからなり、露光済みの印刷版を水平に搬送しながら、ポンプで汲み上げた各処理液をスプレーノズルから吹き付けて現像処理するものである。また、最近は処理液が満たされた処理液槽中に液中ガイドロール等によって印刷用版材を浸漬搬送させて処理する方法も知られている。このような自動処理においては、各処理液に処理量や稼働時間等に応じて補充液を補充しながら処理することができる。また、電気伝導度をセンサーにて感知し、自動的に補充することもできる。また、実質的に未使用の処理液で処理するいわゆる使い捨て処理方式も適用できる。この方法によれば、経時的な炭酸ガスによる現像性の低下や現像液に起因する耐刷性の低下の懸念がないため、これらの自動現像機のいずれにも本発明に係る方法を好適に適用することができる。
【００９４】
以上のようにして得られた平版印刷版は所望により不感脂化ガムを塗布したのち、印刷工程に供することができるが、より一層の高耐刷力の平版印刷版としたい場合にはバーニング処理が施される。
平版印刷版をバーニングする場合には、バーニング前に特公昭６１−２５１８号、同５５−２８０６２号、特開昭６２−３１８５９号、同６１−１５９６５５号の各公報に記載されているような整面液で処理することが好ましい。
【００９５】
その方法としては、該整面液を浸み込ませたスポンジや脱脂綿にて、平版印刷版上に塗布するか、整面液を満たしたバット中に印刷版を浸漬して塗布する方法や、自動コーターによる塗布等が適用される。また、塗布した後でスキージ又はスキージローラーで、その塗布量を均一にすることは、より好ましい結果を与える。整面液の塗布量は一般に０．０３〜０．８ｇ／ｍ^２（乾燥質量）が適当である。
【００９６】
整面液が塗布された平版印刷版は、必要であれば乾燥された後、バーニングプロセッサー（例えば、富士写真フイルム（株）より販売されているバーニングプロセッサー：ＢＰ−１３００）等で高温に加熱される。この場合の加熱温度及び時間は、画像を形成している成分の種類にもよるが、１８０〜３００℃の範囲で１〜２０分の範囲が好ましい。
【００９７】
バーニング処理された平版印刷版は、必要に応じて適宜、水洗、ガム引き等の従来行なわれている処理を施こすことができるが、水溶性高分子化合物等を含有する整面液が使用された場合にはガム引きなどのいわゆる不感脂化処理を省略することができる。
【００９８】
このような処理によって得られた平版印刷版は、オフセット印刷機等にかけられ、多数枚の印刷に用いられる。
【００９９】
【実施例】
以下、実施例により、本発明を詳細に説明するが、本発明はこれらに限定されるものではない。
〔実施例１〜３、比較例１〜３〕
［支持体の作成］
厚さ０．３０ｍｍのアルミニウムウエッブ（材質１０５０）を、表面の圧延油を除去するため１０％アルミン酸ソーダ水溶液で５０℃３０秒間脱脂処理を行い、３０％硫酸水溶液で５０℃３０秒間中和、スマット除去処理を行った。
【０１００】
次いで支持体と記録層の密着性を良好にし、砂目立て処理を行った。１％の塩酸と０．５％の硝酸アルミを含有する水溶液を４５℃に保ち、アルミウェブを水溶液中に流しながら、間接給電セルにより電流密度２０Ａ／ｄｍ^２、デューティー比１：１の交番波形でアノード側電気量２４０Ｃ／ｄｍ^２を与えることで電解砂目立てを行った。その後１０％アルミン酸ソーダ水溶液で５０℃３０秒間エッチング処理を行い、３０％硫酸水溶液で５０℃３０秒間中和、スマット除去処理を行った。
【０１０１】
さらに、電解質として硫酸２０％水溶液を３５℃で用い、アルミウェブを電解質中に通搬しながら、間接給電セルにより１４Ａ／ｄｍ^２の直流で電解処理を行うことで２．５ｇ／ｍ^２の陽極酸化皮膜を作成した。作成したアルミニウム支持体に下記下塗り液をワイヤーバーにて塗布し、温風式乾燥装置を用いて９０℃で３０秒間乾燥した。乾燥後の被服量は２０ｍｇ／ｍ^２であった。
【０１０２】
［下塗り］
次に、このアルミニウム支持体に下記下塗り液をワイヤーバーにて塗布し、温風式乾燥装置を用いて９０℃で３０秒間乾燥した。乾燥後の被服量は１０ｍｇ／ｍ^２であった。
【０１０３】
＜下塗り液＞
・２−メタクリロイルオキシエチルリン酸　　　　　　　　　　　　０．４ｇ
・メタノール　　　　　　　　　　　　　　　　　　　　　　　　　　２０ｇ
・イオン交換水　　　　　　　　　　　　　　　　　　　　　　　　　８０ｇ
【０１０４】
［感光層］
先に、以下の感光層塗布液にバインダーとして添加する高分子化合物（Ｐ−１）を合成した。
＜高分子化合物（Ｐ−１）の合成＞
１０００ｍｌフラスコに、Ｎ，Ｎ−ジメチルアセトアミド７０ｇを入れ、窒素気流下、７０℃まで加熱した。以下に示す化合物（Ａ−１）３３．５ｇ、メタクリルアミド６．８ｇ、メタクリル酸メチル１２．０ｇ、メタクリル酸６．９ｇ、Ｖ−５９（和光純薬製）０．５３８ｇのＮ，Ｎ−ジメチルアセトアミド７０ｇ溶液を、２．５時間かけて滴下した。滴下終了後、９０℃まで加熱し、更に２時間撹拌した。室温まで、反応溶液を冷却した後、水３．５Ｌに投入し、高分子化合物を析出させた。析出した高分子化合物を濾取、水で洗浄、乾燥し、高分子化合物を４８．５ｇ得た。得られた高分子化合物をポリスチレンを標準物質としたゲルパーミエーションクロマトグラフィー法（ＧＰＣ）により、重量平均分子量を測定した結果、１２４，０００であった。また、滴定により酸価を求めたところ、１．３０ｍｅｑ／ｇ（計算値１．３５ｍｅｑ／ｇ）であり、正常に重合が行われたことが確認された。
【０１０５】
２００ｍｌ三口フラスコに、得られた高分子化合物２６．０ｇ、ｐ−メトキシフェノール０．１を入れ、Ｎ，Ｎ−ジメチルアセトアミド６０ｇに溶解した。溶解した後に、氷水を入れた氷浴にて冷却した。混合液温度が５℃以下になった後に、１，８−ジアザビシクロ〔５．４．０〕−７−ウンデセン（ＤＢＵ）３０．４ｇを滴下ロートを用いて、１時間かけて滴下した。滴下終了後、氷浴を外してさらに８時間撹拌した。反応液を濃塩酸１７ｍｌを溶解させた水２Ｌに投入し高分子化合物（Ｐ−１）を析出させた。析出した高分子化合物を濾取、水で洗浄、乾燥し、高分子化合物（Ｐ−１）を１８．２ｇ得た。得られた高分子化合物（Ｐ−１）のＨ−ＮＭＲを測定したところ、化合物（Ａ−１）由来の側鎖基の１００％がエチレンメタクリレート基に変換されたことが確認された。また、ポリスチレンを標準物質としたゲルパーミエーションクロマトグラフィー法（ＧＰＣ）により、重量平均分子量を測定した結果、１１４，０００であった。さらに、滴定により酸価を求めたところ、０．９ｍｅｑ／ｇ（計算値０．８ｍｅｑ／ｇ）であった。
【０１０６】
【化３】

【０１０７】
次に、下記感光層塗布液を調整し、上記下塗り済みのアルミニウム板にワイヤーバーを用いて塗布し、温風式乾燥装置にて１２０℃で４５秒間乾燥して感光層を形成した。乾燥後の被覆量は２．０ｇ／ｍ^２であった。
【０１０８】
＜感光層塗布液＞
・以下に示される構造の赤外線吸収剤　　　　　　　　　　　　　０．１０ｇ
・以下に示される構造のラジカル発生剤　　　　　　　　　　　　０．１５ｇ
・ジペンタエリスリトールヘキサアクリレート　　　　　　　　　　１．０ｇ
・上記で得られた高分子化合物（Ｐ−１）　　　　　　　　　　　　１．０ｇ
・クリスタルバイオレット　　　　　　　　　　　　　　　　　　０．０６ｇ
・フッ素系界面活性剤　　　　　　　　　　　　　　　　　　　　０．０１ｇ
（メガファックＦ−１７６、大日本インキ化学工業（株）製）
・ステアロイルメチルアミド　　　　　　　　　　　　　　　　　０．０２ｇ
・メチルエチルケトン　　　　　　　　　　　　　　　　　　　　１４．０ｇ
・メタノール　　　　　　　　　　　　　　　　　　　　　　　　　６．５ｇ
・１−メトキシ−２−プロパノール　　　　　　　　　　　　　　１０．０ｇ
【０１０９】
【化４】

【０１１０】
さらに、下記オーバーコート層塗布液をスライドホッパーを用いて塗布し、温風式乾燥装置にて１２０℃で７５秒間乾燥し、本発明の平版印刷版原版を得た。なお、塗布・乾燥後のオーバーコート層の膜重量（ｇ／ｍ^２）を表１に記す。
【０１１１】
＜オーバーコート層塗布液＞
・ポリビニルアルコール　　　　　　　　　　　　　　　　　　　　２．５ｇ
（ＰＶＡ１０５：クラレ（株）製、ケン化度９８．５％、重合度５００）
・ポリビニルピロリドン　　　　　　　　　　　　　　　　　　　　０．５ｇ
（Ｋ３０、東京化成工業（株）製　分子量４万）
・非イオン性界面活性剤　　　　　　　　　　　　　　　　　　　０．０５ｇ
（ＥＭＡＲＥＸ　ＮＰ−１０　日本エマルジョン社（株）製）
・イオン交換水　　　　　　　　　　　　　　　　　　　　　　９６．９５ｇ
【０１１２】
〔感度および現像性の評価〕
上記で得られた平版印刷版原版を水冷式４０Ｗ赤外線半導体レーザを搭載したＣｒｅｏ社製Ｔｒｅｎｄｓｅｔｔｅｒ３２４４にて、露光エネルギーを変えてテストパターンを画像状に描き込んだ。
次に、富士写真フイルム（株）製自動現像機ＬＰ−９４０Ｈに、現像液ＤＶ−２（希釈して、ｐＨ１２．０（２５℃）としたもの）を投入し、上記平版印刷版原版を搬送速度を変えて通し、印刷版の画像部が取り切れるのに必要な現像液浸漬時間を測定した。この時、先の画像描き込みにより、露光部が十分に硬化し、画像が形成されていた露光エネルギーを測定し、感度とした。数値が小さいほど高感度であることを示す。感度および現像に要した時間の結果を表１に記す。
【０１１３】
【表１】

【０１１４】
表１によれば、オーバーコート層の膜重量を、０．０５ｇ／ｍ^２以上、１．０ｇ／ｍ^２以下に調整して設けた本発明のいずれの平版印刷版原版も、オーバーコート層本来の目的である感度の向上効果を確保しながらも、且つ、プレ水洗などの煩雑な工程を含まない、短時間の現像処理により非画像部が除去されたことが確認された。
一方、オーバーコート層を設けなかった比較例１の平版印刷版原版は、現像時間は短いものの、感度に劣っており、比較例２および３の平版印刷版原版は、感度には優れるが、オーバーコート層の膜重量が多いため実施例に比較して現像に時間を要することが分かった。
【０１１５】
〔実施例４〜６、比較例４、５〕
上記実施例１〜３における、オーバーコート層中のポリビニルアルコール（ＰＶＡ１０５：クラレ（株）製、ケン化度９８．５％、重合度５００）を、イタコン酸変性ポリビニルアルコール（ＫＭ−１１８：クラレ社（株）製、ケン化度９５．５〜９８．５％）に変更して、オーバーコート層の塗布量を下記表２に記したものに変更した以外は、実施例１〜３と同様にして、平版印刷版原版を作成し、同様の評価を行った。結果を表２に併記する。
【０１１６】
【表２】

【０１１７】
表２によれば、オーバーコート層の膜重量を、０．０５ｇ／ｍ^２以上、１．０ｇ／ｍ^２以下に調整して設けた本発明のいずれの平版印刷版原版も、オーバーコート層本来の目的である感度の向上効果を確保しながらも、且つ、プレ水洗などの煩雑な工程を含まない、短時間の現像処理により非画像部が除去されたことが確認された。また、実施例１〜３と比較しても現像性が向上していることがわかった。
一方、オーバーコート層の膜重量が１．０以上である比較例４および５の平版印刷版原版は、感度には優れるが、実施例に比較して現像に時間を要することが分かった。
【０１１８】
【発明の効果】
本発明によれば、赤外線を放射する固体レーザ及び半導体レーザを用いて記録することにより、コンピューター等のデジタルデータから直接記録可能であり、高感度、且つ、現像性に優れたネガ型平版印刷版原版を得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lithographic printing plate precursor, and more particularly, to a so-called negative lithographic printing plate precursor capable of direct plate making using an infrared laser from a digital signal of a computer or the like.
[0002]
[Prior art]
Conventionally, as a system for making a plate directly from digital data of a computer, (1) an electrophotographic method, (2) a photopolymerization system using a blue or green light emitting laser, and (3) a silver salt is exposed. Those laminated on a functional resin, and (4) a silver salt diffusion transfer method have been proposed.
[0003]
However, in the method using the electrophotography (1), the image forming process such as charging, exposure and development is complicated, and the apparatus becomes complicated and large. Further, in the photopolymerization system (2), since a plate material with high sensitivity to blue or green light is used, handling in a bright room becomes difficult. The methods {circle around (3)} and {circle around (4)} have disadvantages such that the processing such as development becomes complicated because silver salt is used, and silver is contained in the processing waste liquid.
[0004]
On the other hand, the development of lasers in recent years is remarkable, and in particular, solid lasers and semiconductor lasers that emit infrared rays having a wavelength of 760 nm to 1200 nm are easily available in high output and small size. These lasers are very useful as a recording light source when directly making a plate from digital data such as a computer. However, since many photosensitive recording materials useful in practical use have a photosensitive wavelength in the visible light range of 760 nm or less, image recording cannot be performed with these infrared lasers. Therefore, a material that can be recorded with an infrared laser is desired.
[0005]
As an image recording material that can be recorded by such an infrared laser, there is a recording material composed of an onium salt, a phenol resin, and a spectral sensitizer (see Patent Document 1). This image recording material is a positive-type image recording material that utilizes a dissolution inhibiting effect on a developing solution expressed by an onium salt and a phenol resin, and is not a negative type as in the present invention. On the other hand, as a negative image recording material, a recording material comprising an infrared absorber, an acid generator, a resole resin and a novolac resin is disclosed (see Patent Document 2). However, such a negative type image recording material requires a heat treatment after laser exposure for image formation. Therefore, a negative type image recording material that does not require a heat treatment after exposure is desired. It was.
For example, although a recording material comprising a cyanine dye having a specific structure, an iodonium salt, and an addition-polymerizable compound having an ethylenically unsaturated double bond and not requiring heat treatment after imagewise exposure is disclosed ( In this image recording material, there is a problem that the polymerization is inhibited by oxygen in the air during the polymerization reaction, the sensitivity is lowered, and the strength of the formed image portion is insufficient.
[0006]
As a means for preventing this polymerization inhibition, for example, a technique of providing an overcoat layer having optical transparency and photosensitivity is disclosed (see Patent Document 4). For such an overcoat layer, polyvinyl alcohol, which is usually excellent in oxygen barrier properties and easily available, is used, and by blocking oxygen in the atmosphere by such an overcoat layer, polymerization inhibition is prevented, The effect of improving sensitivity and storage stability has been achieved.
However, when an overcoat layer using polyvinyl alcohol is used, it is necessary to remove the overcoat layer during development. There is a disadvantage that a complicated process is required, such as a process of performing and removing the overcoat layer (hereinafter appropriately referred to as pre-water washing).
In addition, in both cases where the overcoat layer is removed in the pre-washing tank or the developing tank, the larger the film weight, the more concentrated the overcoat layer components of the developer solution, and problems such as piping clogging are likely to occur. However, there was a problem that the amount of waste liquid increased in practice.
[0007]
[Patent Document 1]
US Pat. No. 4,708,925
[Patent Document 2]
US Pat. No. 5,340,699
[Patent Document 3]
Japanese Examined Patent Publication No. 7-103171
[Patent Document 4]
Japanese Patent Laid-Open No. 10-228109
[0008]
[Problems to be solved by the invention]
The object of the present invention, which has been made in consideration of the above-mentioned drawbacks of the prior art, is to be recorded directly from digital data such as a computer by recording using a solid-state laser and a semiconductor laser that emits infrared rays, Another object is to provide a negative lithographic printing plate precursor excellent in developability.
[0009]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that the above object can be achieved by adjusting the film weight of the overcoat layer provided on the photosensitive layer of the lithographic printing plate precursor, and have solved the present invention. It was.
That is, the lithographic printing plate precursor according to the present invention contains (A) an infrared absorber, (B) a radical generator, and (C) a radical polymerizable compound on a support, and is cured by infrared irradiation. A photosensitive layer that causes
The membrane weight during drying is 0.05 g / m ² 1.0 g / m ² The following overcoat layers;
Are sequentially provided.
Moreover, in this invention, it is mentioned as a preferable aspect that at least 1 type is contained among polyvinyl alcohol and acid-modified polyvinyl alcohol as a component of the said overcoat layer.
[0010]
In the lithographic printing plate precursor according to the invention, the film weight of the overcoat layer provided on the photosensitive layer is 0.05 g / m. ² 1.0 g / m ² By ensuring the following improvements in image forming properties and sensitivity, which are the original objectives of the overcoat layer, and excellent developability can be obtained, the development time can be shortened or complicated, such as pre-washing The process can be omitted.
Further, as a component of such an overcoat layer, it is preferable to contain at least one of unmodified polyvinyl alcohol and acid-modified polyvinyl alcohol from the viewpoint of oxygen barrier properties and development removability, and in particular, acid modification Polyvinyl alcohol is particularly preferable because it has high hydrophilicity and further improves development removability.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The planographic printing plate precursor of the present invention contains (A) an infrared absorber, (B) a radical generator, and (C) a radical polymerizable compound on a support, and causes a curing reaction by infrared irradiation. The photosensitive layer to be dried and the film weight when dried to 0.05 g / m ² 1.0 g / m ² The following overcoat layers are sequentially provided.
First, the overcoat layer, which is a characteristic configuration of the present invention, will be described in detail.
[0012]
[Membrane weight when dried is 0.05 g / m ² 1.0 g / m ² (The following overcoat layer)
[Components of overcoat layer]
The composition of the overcoat layer used in the present invention is not particularly limited, and for example, known ones described in detail in US Pat. No. 3,458,311 and JP-A-55-49729 are used. Can do. The material that can be used for such an overcoat layer is preferably selected from natural and synthetic polymers that can be dissolved in water or an aqueous alkaline solution, and can form a film when coated and dried. Specifically, for natural polymers, gum arabic, water-soluble soybean polysaccharide, fiber derivatives (for example, carboxymethylcellulose, carboxyethylcellulose, methylcellulose, etc.), modified products thereof, white dextrin, pullulan, enzymatically degraded etherified dextrin, etc. Synthetic polymers include polyvinyl alcohol, its butyral derivative, polyacrylic acid, its alkali metal salt or amine salt, polyacrylic acid copolymer, its alkali metal salt or amine salt, polymethacrylic acid, its alkali metal salt or amine Salt, vinyl alcohol / acrylic acid copolymer and alkali metal salt or amine salt thereof, polyacrylamide, copolymer thereof, polyhydroxyethyl acrylate, polyvinyl pyrrolidone, copolymer thereof, polyvinyl methyl ether , Vinyl methyl ether / maleic anhydride copolymer, poly-2-acrylamido-2-methyl-1-propanesulfonic acid, alkali metal salt or amine salt thereof, poly-2-acrylamido-2-methyl-1-propane Examples thereof include sulfonic acid copolymers and alkali metal salts or amine salts thereof.
[0013]
Among these, it is preferable to use polyvinyl alcohol as a main component from the viewpoint of basic characteristics such as oxygen barrier properties and development removability. Examples of such polyvinyl alcohol include unmodified polyvinyl alcohol and acid-modified polyvinyl alcohol modified with carboxylic acid or a salt thereof, sulfonate, or the like. Among them, acid-modified polyvinyl alcohol with improved hydrophilicity is preferable from the viewpoint of developability. Specifically, for example, acid-modified polyvinyl alcohol such as itaconic acid or maleic acid-modified carboxy-modified polyvinyl alcohol or sulfonic acid-modified polyvinyl alcohol Is mentioned.
In addition, the polyvinyl alcohol used for the overcoat layer may be partially substituted with an ester, an ether, and an acetal as long as it contains an unsubstituted vinyl alcohol unit to have the necessary oxygen barrier properties and water solubility. Also, some of them may have other copolymerization components as well.
[0014]
Specific examples of such polyvinyl alcohol include those having a hydrolysis degree of 71 to 100% and a polymerization degree in the range of 300 to 2400. Specifically, KL-504, KL-506, KL-318, KL-118, KM-618, KM-118, SK-5102, PVA-105, PVA-110, PVA-117 made by Kuraray Co., Ltd. , PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA-HC, PVA-203, PVA-204, PVA-205, PVA-210, PVA-217, PVA -220, PVA-224, PVA-217EE, PVA-217E, PVA-220E, PVA-224E, PVA-405, PVA-420, PVA-613, L-8 and the like.
[0015]
The component of the overcoat layer, that is, what kind of compound is selected as PVA, whether or not the use of the additive is necessary, and the amount added are the oxygen barrier property, development removability, fogging property, adhesion property, and scratch resistance. Is selected.
In general, the higher the hydrolysis rate of the PVA used (the higher the content of unsubstituted vinyl alcohol units in the overcoat layer), the higher the oxygen barrier property, which is advantageous in terms of sensitivity. However, when the oxygen barrier property is extremely increased, there arises a problem that unnecessary polymerization reaction occurs during production and raw storage, and unnecessary fogging and image line thickening occur during image exposure.
[0016]
In view of these viewpoints, the overcoat layer of the present invention is an acid-modified PVA having excellent oxygen barrier properties and good developability, specifically, itaconic acid or maleic acid-modified carboxylic acid-modified polyvinyl alcohol. It is most preferable to use acid-modified polyvinyl alcohol such as sulfonic acid-modified polyvinyl alcohol. Such acid-modified PVA is also available as a commercial product such as KL-504, KL-506, KL-318, KL-118, KM-618, KM-118, SK-5102, manufactured by Kuraray Co., Ltd. It is available.
[0017]
In addition, adhesion to the image area and scratch resistance are extremely important in handling the plate. That is, when a hydrophilic layer made of a water-soluble polymer is laminated on a new oil-based recording layer, film peeling due to insufficient adhesion tends to occur, and the peeled part causes defects such as poor film hardening due to inhibition of oxygen polymerization.
Therefore, various proposals have been made to improve the adhesion between these two layers. For example, US Pat. No. 292,501 and US Pat. No. 44,563 disclose a hydrophilic polymer mainly composed of polyvinyl alcohol. Further, it is described that sufficient adhesion can be obtained by mixing 20 to 60% by mass of an acrylic emulsion or a water-insoluble vinylpyrrolidone-vinyl acetate copolymer and laminating the mixture on a recording layer. Any of these known techniques can be applied to the overcoat layer in the present invention.
[0018]
Further, these overcoat layers are excellent in the transmittance of light used for exposure (for example, a wavelength of 760 to 1200 nm for an infrared laser) and can efficiently absorb light having a wavelength not related to exposure (water-soluble). Addition of a functional dye or the like) can improve the suitability for safelight without causing a decrease in sensitivity.
[0019]
[Application of overcoat layer]
The overcoat layer used in the present invention may be usually coated on a suitable support by dissolving the above-described components necessary for the overcoat layer coating solution in a solvent.
As a solvent used here, water is used as a main component, but from the viewpoint of coating physical property control such as surface tension and viscosity of the coating liquid and solubility control of the lower layer, alcohols such as methanol, and glycols such as glycerin. In addition, amides such as ethanolformamide and dimethyl sulfoxide can be mixed and used, but are not limited thereto.
The concentration of the above components (total solid content including additives) in the solvent is preferably 0.01 to 50 mass%, more preferably 1 to 20 mass%.
[0020]
A surfactant may be added to the overcoat layer coating solution according to the present invention in order to improve coating properties. Specific examples of such surfactants include polyoxyethylene lauryl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene laurate, polyoxyethylene stearamide, polyoxyethylene lauryl amine, polyoxyethylene polyoxypropylene Examples include ether, glycerol monourarate, sorbitan tristearate, sorbitan monopalmitate, polyoxyethylene sorbitan trioleate, alkylallyl ether formalin condensate, naphthalenesulfonic acid terformalin condensate and the like.
A preferable addition amount is 0.01 to 5% by mass, more preferably 0.1 to 3% by mass, in the above-described components (total solid content including additives) in the solvent.
[0021]
The coating amount obtained after coating and drying the overcoat layer is 0.05 g / m. ² 1.0 g / m ² The following is sufficient, 0.1 to 1.0 g / m ² Is preferably in the range of 0.2 to 0.75 g / m ² Is more preferable.
0.05g / m ² If it is less than 1, the oxygen barrier property is inferior and sufficient sensitivity cannot be obtained, and 1.0 g / m ² If the amount is larger, the removability of the overcoat layer at the time of development is inferior, a development time is required, and a complicated development process such as pre-washing is required.
[0022]
Various methods can be used as the coating method, such as bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, roll coating, and extrusion coating. Can be mentioned.
[0023]
(Photosensitive layer)
The photosensitive layer used in the present invention absorbs infrared light at the time of exposure and converts it into thermal energy (A) an infrared absorbent, and generates a radical when the thermal energy is applied (B) a radical generator (radical). A polymerization initiator) and (C) a radically polymerizable compound that cures by causing a polymerization reaction with the generated radicals, and preferably (D) a binder polymer from the viewpoint of improving the film strength.
Hereinafter, each compound used for the photosensitive layer of the negative lithographic printing plate precursor will be described in detail.
[0024]
[(A) Infrared absorber]
The infrared absorber used in the present invention is not particularly limited as long as it has a function of converting absorbed infrared light into heat, and a known infrared absorber can be appropriately selected and used. The infrared absorber is exposed by an infrared laser, and the generated heat decomposes the radical generator and the acid generator to generate radicals and acids. The infrared absorber used in the present invention is a dye or pigment having an absorption maximum at a wavelength of 760 nm to 1200 nm.
[0025]
As the dye, commercially available dyes and known dyes described in documents such as “Dye Handbook” (edited by the Society for Synthetic Organic Chemistry, published in 1970) can be used. Specifically, dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes, etc. Is mentioned.
[0026]
Preferred dyes include, for example, cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-59-202829, JP-A-60-78787, and the like. Methine dyes described in JP-A-58-173696, JP-A-58-181690, JP-A-58-194595, JP-A-58-112793, JP-A-58-224793, JP-A-59- 48187, JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, etc., naphthoquinone dyes, JP-A-58-112792, etc. And cyanine dyes described in British Patent 434,875.
[0027]
Also, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is preferably used, and a substituted arylbenzo (thio) pyrylium salt described in US Pat. No. 3,881,924, Trimethine thiapyrylium salts described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, 58-220143, 59-41363, 59-84248 Nos. 59-84249, 59-146063, 59-146061, pyranlium compounds, cyanine dyes described in JP-A-59-216146, US Pat. No. 4,283,475 The pentamethine thiopyrylium salts described above and the pyrylium compounds disclosed in Japanese Patent Publication Nos. 5-13514 and 5-19702 are also preferably used. .
Another example of a preferable dye is a near-infrared absorbing dye described as formulas (I) and (II) in US Pat. No. 4,756,993.
[0028]
Among these dyes, particularly preferred are cyanine dyes, squarylium dyes, pyrylium salts, and nickel thiolate complexes. Further, a cyanine dye is preferable, and a cyanine dye represented by the following general formula (I) is most preferable.
[0029]
[Chemical 1]

[0030]
In the general formula (I), X ¹ Is a halogen atom or X ² -L ¹ Indicates. Where X ² Represents an oxygen atom or a sulfur atom, and L ¹ Represents a hydrocarbon group having 1 to 12 carbon atoms. R ¹ And R ² Each independently represents a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the photosensitive layer coating solution, R ¹ And R ² Is preferably a hydrocarbon group having 2 or more carbon atoms, and further R ¹ And R ² Are particularly preferably bonded to each other to form a 5-membered ring or a 6-membered ring.
[0031]
Ar ¹ , Ar ² These may be the same or different and each represents an aromatic hydrocarbon group which may have a substituent. Preferred aromatic hydrocarbon groups include a benzene ring and a naphthalene ring. Moreover, as a preferable substituent, a C12 or less hydrocarbon group, a halogen atom, and a C12 or less alkoxy group are mentioned. Y ¹ , Y ² May be the same or different and each represents a sulfur atom or a dialkylmethylene group having 12 or less carbon atoms. R ³ , R ⁴ These may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferred substituents include alkoxy groups having 12 or less carbon atoms, carboxyl groups, and sulfo groups. R ⁵ , R ⁶ , R ⁷ And R ⁸ Each may be the same or different and each represents a hydrogen atom or a hydrocarbon group having 12 or less carbon atoms. From the availability of raw materials, a hydrogen atom is preferred. Z ^1- Represents a counter anion. However, R ¹ ~ R ⁸ Z is substituted with a sulfo group ^1- Is not necessary. Preferred Z ^1- Is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion, a hexafluorophosphate in view of the storage stability of the photosensitive layer coating solution. An ion, and an aryl sulfonate ion.
[0032]
Specific examples of the cyanine dye represented by formula (I) that can be suitably used in the present invention include those described in paragraph numbers [0017] to [0019] of JP-A No. 2001-133969. be able to.
[0033]
Examples of the pigment used in the present invention include commercially available pigments and color index (CI) manual, “Latest Pigment Handbook” (edited by Japan Pigment Technology Association, published in 1977), “Latest Pigment Application Technology” (CMC Publishing, 1986), “Printing Ink Technology”, CMC Publishing, 1984) can be used.
Examples of the pigment include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded dyes. Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments In addition, quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Among these pigments, carbon black is preferable.
[0034]
These pigments may be used without surface treatment, or may be used after surface treatment. The surface treatment method includes a method of surface coating with a resin or wax, a method of attaching a surfactant, a method of bonding a reactive substance (eg, silane coupling agent, epoxy compound, polyisocyanate, etc.) to the pigment surface, etc. Can be considered. The above-mentioned surface treatment methods are described in “Characteristics and Applications of Metal Soap” (Yokoshobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.
[0035]
The particle size of the pigment is preferably in the range of 0.01 μm to 10 μm, more preferably in the range of 0.05 μm to 1 μm, and particularly preferably in the range of 0.1 μm to 1 μm. When the particle diameter of the pigment is less than 0.01 μm, it is not preferable from the viewpoint of stability of the dispersion in the photosensitive layer coating solution, and when it exceeds 10 μm, it is not preferable from the viewpoint of uniformity of the photosensitive layer.
[0036]
As a method for dispersing the pigment, a known dispersion technique used in ink production, toner production, or the like can be used. Examples of the disperser include an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a disperser, a KD mill, a colloid mill, a dynatron, a three-roll mill, and a pressure kneader. Details are described in "Latest Pigment Applied Technology" (CMC Publishing, 1986).
[0037]
The addition amount of these infrared absorbers is preferably such that the optical density at the absorption maximum in the wavelength range of 760 nm to 1200 nm of the photosensitive layer in the present invention is in the range of 0.1 to 3.0. When this range is deviated, the sensitivity tends to be low. Since the optical density is determined by the amount of the infrared absorber added and the thickness of the photosensitive layer, the predetermined optical density can be obtained by controlling both conditions. The optical density of the photosensitive layer can be measured by a conventional method. As a measuring method, for example, on a transparent or white support, a photosensitive layer having a thickness appropriately determined in a range where the coating amount after drying is necessary as a lithographic printing plate is formed, and a transmission type optical densitometer is used. Examples thereof include a method of measuring, a method of forming a photosensitive layer on a reflective support such as aluminum, and measuring a reflection density.
[0038]
[(B) Radical generator]
The radical generator used in the present invention refers to a compound that is used in combination with (A) an infrared absorber and generates radicals when irradiated with an infrared laser. Examples of the radical generator include an onium salt, a triazine compound having a trihalomethyl group, a peroxide, an azo polymerization initiator, an azide compound, a quinonediazide, and a borate compound, and an onium salt is preferable because of its high sensitivity. An onium salt that can be suitably used as a radical polymerization initiator in the present invention will be described. Preferred onium salts include iodonium salts, diazonium salts, and sulfonium salts. In the present invention, these onium salts function not as acid generators but as radical polymerization initiators. The onium salt suitably used in the present invention is an onium salt represented by the following general formulas (II) to (IV).
[0039]
[Chemical 2]

[0040]
In formula (II), Ar ¹¹ And Ar ¹² Each independently represents an aryl group having 20 or less carbon atoms, which may have a substituent. Preferred substituents when this aryl group has a substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or a carbon atom having 12 or less carbon atoms. An aryloxy group is mentioned. Z ^11- Represents a counter ion selected from the group consisting of halogen ion, perchlorate ion, tetrafluoroborate ion, hexafluorophosphate ion, carboxylate ion, and sulfonate ion, preferably perchlorate ion, hexafluorophosphate Fate ions, carboxylate ions, and aryl sulfonate ions.
[0041]
In formula (III), Ar ²¹ Represents an aryl group having 20 or less carbon atoms which may have a substituent. Preferred examples of the substituent include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, an aryloxy group having 12 or less carbon atoms, and 12 or less carbon atoms. Examples thereof include an alkylamino group, a dialkylamino group having 12 or less carbon atoms, an arylamino group having 12 or less carbon atoms, or a diarylamino group having 12 or less carbon atoms. Z ^21- Is Z ^11- Represents a counter ion having the same meaning as.
[0042]
In formula (IV), R ³¹ , R ³² And R ³³ These may be the same or different and each represents a hydrocarbon group having 20 or less carbon atoms which may have a substituent. Preferable substituents include a halogen atom, a nitro group, an alkyl group having 12 or less carbon atoms, an alkoxy group having 12 or less carbon atoms, or an aryloxy group having 12 or less carbon atoms. Z ^31- Is Z ^11- Represents a counter ion having the same meaning as.
[0043]
In the present invention, specific examples of onium salts that can be suitably used as a radical generator include those described in paragraphs [0030] to [0033] of JP-A No. 2001-133969.
[0044]
The radical generator used in the present invention preferably has a maximum absorption wavelength of 400 nm or less, and more preferably 360 nm or less. Thus, by setting the absorption wavelength in the ultraviolet region, the planographic printing plate precursor can be handled under white light.
[0045]
These radical generators are 0.1 to 50% by weight, preferably 0.5 to 30% by weight, particularly preferably 1 to 20% by weight, based on the total solid content of the photosensitive layer coating solution. Can be added inside. When the addition amount is less than 0.1% by mass, the sensitivity is lowered, and when it exceeds 50% by mass, the non-image area is stained during printing. These radical generators may be used alone or in combination of two or more. Moreover, these radical generators may be added to the same layer as other components, or another layer may be provided and added thereto.
[0046]
[(C) Radical polymerizable compound]
The radically polymerizable compound used in the present invention is a radically polymerizable compound having at least one ethylenically unsaturated double bond, from a compound having at least one, preferably two or more terminal ethylenically unsaturated bonds. To be elected. Such a compound group is widely known in the industrial field, and can be used without any particular limitation in the present invention. These have chemical forms such as monomers, prepolymers, i.e. dimers, trimers and oligomers, or mixtures thereof and copolymers thereof. Examples of monomers and copolymers thereof include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters and amides thereof. In this case, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. In addition, unsaturated carboxylic acid ester having a nucleophilic substituent such as hydroxyl group, amino group, mercapto group, amide and monofunctional or polyfunctional isocyanate, addition reaction product of epoxy, monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an isocyanate group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, halogen A substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as a group or a tosyloxy group with a monofunctional or polyfunctional alcohol, amine or thiol is also suitable. As another example, it is also possible to use a group of compounds substituted with unsaturated phosphonic acid, styrene or the like instead of the unsaturated carboxylic acid.
[0047]
Specific examples of acrylic acid ester, methacrylic acid ester, itaconic acid ester, crotonic acid ester, isocrotonic acid ester, maleic acid ester, which are radical polymerizable compounds that are esters of aliphatic polyhydric alcohol compounds and unsaturated carboxylic acids, It describes in paragraph number [0037]-[0042] of Unexamined-Japanese-Patent No. 2001-133969, and these are applicable also to this invention.
[0048]
Examples of other esters include aliphatic alcohol esters described in JP-B-46-27926, JP-B-51-47334, JP-A-57-196231, JP-A-59-5240, JP-A-59-5241. Those having an aromatic skeleton described in JP-A-2-226149 and those containing an amino group described in JP-A-1-165613 are also preferably used.
[0049]
Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like.
Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B-54-21726.
[0050]
In addition, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable, and specific examples thereof include, for example, one molecule described in JP-B-48-41708. A vinyl urethane compound containing two or more polymerizable vinyl groups in one molecule obtained by adding a vinyl monomer containing a hydroxyl group represented by the following formula (V) to a polyisocyanate compound having two or more isocyanate groups. Etc.
[0051]
General formula (V)
CH ₂ = C (R ⁴¹ ) COOCH ₂ CH (R ⁴² ) OH
(However, R ⁴¹ And R ⁴² Is H or CH ₃ Indicates. )
[0052]
Further, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, and JP-B-2-16765, JP-B-58-49860, JP-B-56-17654, Urethane compounds having an ethylene oxide skeleton described in JP-B-62-39417 and JP-B-62-39418 are also suitable.
[0053]
Furthermore, radical polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238 may be used.
[0054]
Other examples include polyester acrylates, epoxy resins and (meth) acrylic acid as described in JP-A-48-64183, JP-B-49-43191, JP-B-52-30490, and JP-A-52-30490. Examples thereof include polyfunctional acrylates and methacrylates such as reacted epoxy acrylates. Further, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337, and JP-B-1-40336, vinylphosphonic acid compounds described in JP-A-2-25493, and the like can also be mentioned. . In some cases, a structure containing a perfluoroalkyl group described in JP-A-61-22048 is preferably used. Furthermore, Journal of Japan Adhesion Association vol. 20, no. 7, pages 300 to 308 (1984), which are introduced as photocurable monomers and oligomers, can also be used.
[0055]
For these radically polymerizable compounds, the details of how to use them, such as what structure to use, whether they are used alone or in combination, and how much they are added, can be selected according to the performance design of the final recording material. Can be set. For example, it is selected from the following viewpoints. From the viewpoint of sensitivity, a structure having a high unsaturated group content per molecule is preferable, and in many cases, a bifunctional or higher functionality is preferable. Further, in order to increase the strength of the image portion, that is, the cured film, those having three or more functionalities are preferable, and further compounds having different functional numbers and different polymerizable groups (for example, acrylate ester compounds, methacrylate esters). It is also effective to adjust both photosensitivity and strength by using a combination of a compound, a styrene compound, and the like.
A compound having a large molecular weight or a compound having high hydrophobicity is excellent in sensitivity and film strength, but may not be preferable in terms of development speed and precipitation in a developer. In addition, the compatibility and dispersibility with other components in the photosensitive layer (for example, binder polymer, initiator, colorant, etc.) are also important factors in selecting and using the radically polymerized compound. Compatibility may be improved by the use of a low-purity compound or a combination of two or more compounds. In addition, a specific structure may be selected for the purpose of improving the adhesion of the support, overcoat layer and the like. Regarding the compounding ratio of the radically polymerizable compound in the photosensitive layer, a larger amount is advantageous in terms of sensitivity, but if it is too much, undesirable phase separation occurs or a problem in the production process due to the adhesiveness of the photosensitive layer. For example, problems such as transfer of photosensitive layer components and manufacturing defects due to adhesion, and precipitation from a developer may occur. From these viewpoints, the preferable blending ratio of the radically polymerizable compound is often 5 to 80% by mass, preferably 20 to 75% by mass with respect to the total components of the composition. These may be used alone or in combination of two or more. In addition, the usage method of the radical polymerizable compound can be arbitrarily selected from the viewpoint of polymerization inhibition with respect to oxygen, resolution, fogging, refractive index change, surface adhesiveness, etc. Depending on the case, a layer configuration and coating method such as undercoating and overcoating can be performed.
[0056]
[(D) Binder polymer]
In the present invention, from the viewpoint of improving the film strength, it is preferable to further use a binder polymer in the photosensitive layer, and it is preferable to use a linear organic polymer as the binder. As such a “linear organic polymer”, a known one can be arbitrarily used. Preferably, a linear organic polymer that is soluble or swellable in water or weak alkaline water is selected to enable water development or weak alkaline water development. The linear organic polymer is selected and used not only as a film forming agent for forming the photosensitive layer but also according to the use as water, weak alkaline water or an organic solvent developer. For example, when a water-soluble organic polymer is used, water development becomes possible. Examples of such linear organic polymers include radical polymers having a carboxylic acid group in the side chain, such as JP-A-59-44615, JP-B-54-34327, JP-B-58-12777, and JP-B-54-25957. , JP 54-92723, JP 59-53836, JP 59-71048, ie, methacrylic acid copolymer, acrylic acid copolymer, itaconic acid copolymer. Examples thereof include a polymer, a crotonic acid copolymer, a maleic acid copolymer, and a partially esterified maleic acid copolymer. Similarly, there is an acidic cellulose derivative having a carboxylic acid group in the side chain. In addition, those obtained by adding a cyclic acid anhydride to a polymer having a hydroxyl group are useful.
[0057]
Among these, a resin having an ethylenically unsaturated double bond such as an allyl group, a (meth) acryloyl group, and a (meth) acrylamide group and a carboxyl group in the side chain balances film strength, sensitivity, and developability. And is suitable.
[0058]
Also, Japanese Patent Publication No. 7-120040, Japanese Patent Publication No. 7-120041, Japanese Patent Publication No. 7-120042, Japanese Patent Publication No. 8-12424, Japanese Patent Publication No. 63-287944, Japanese Patent Publication No. 63-287947, Japanese Patent Publication No. Hei 1 Urethane-based binder polymers containing acid groups described in No. 271741, JP-A-11-352691 and the like are very excellent in strength, and are advantageous in terms of printing durability and suitability for low exposure.
[0059]
In addition, polyvinyl pyrrolidone, polyethylene oxide, and the like are useful as the water-soluble linear organic polymer. In order to increase the strength of the cured film, alcohol-soluble nylon, polyether of 2,2-bis- (4-hydroxyphenyl) -propane and epichlorohydrin, and the like are also useful.
[0060]
The mass average molecular weight of the polymer used in the present invention is preferably 5000 or more, more preferably 10,000 to 300,000, and the number average molecular weight is preferably 1000 or more, more preferably 2000 to 2000 The range is 250,000. The polydispersity (weight average molecular weight / number average molecular weight) is preferably 1 or more, and more preferably 1.1 to 10.
[0061]
These polymers may be random polymers, block polymers, graft polymers or the like, but are preferably random polymers.
[0062]
The polymer used in the present invention can be synthesized by a conventionally known method. Solvents used in the synthesis include, for example, tetrahydrofuran, ethylene dichloride, cyclohexanone, methyl ethyl ketone, acetone, methanol, ethanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 2-methoxyethyl acetate, diethylene glycol dimethyl ether, 1-methoxy. Examples include 2-propanol, 1-methoxy-2-propyl acetate, N, N-dimethylformamide, N, N-dimethylacetamide, toluene, ethyl acetate, methyl lactate, ethyl lactate, dimethyl sulfoxide, and water. These solvents are used alone or in combination of two or more.
[0063]
As the radical polymerization initiator used for synthesizing the polymer used in the present invention, known compounds such as azo initiators and peroxide initiators can be used.
[0064]
The binder polymer used in the present invention may be used alone or in combination. These polymers are added to the photosensitive layer in a proportion of 20 to 95% by mass, preferably 30 to 90% by mass, based on the total solid content of the photosensitive layer coating solution. When the addition amount is less than 20% by mass, the strength of the image portion is insufficient when an image is formed. If the amount added exceeds 95% by mass, no image is formed. Moreover, it is preferable that the compound which has an ethylenically unsaturated double bond which can be radically polymerized, and a linear organic polymer shall be 1 / 9-7 / 3 by mass ratio.
[0065]
[Other ingredients]
The photosensitive layer of the lithographic printing plate precursor according to the present invention may be added with various compounds as necessary in order to improve not only the components related to film curing but also the characteristics and handling properties as a lithographic printing plate precursor. May be.
For example, a dye having a large absorption in the visible light region can be used as an image colorant. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (orientated chemistry) Manufactured by Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), etc., and JP-A-62-2 And dyes described in No. 293247. In addition, pigments such as phthalocyanine pigments, azo pigments, carbon black, and titanium oxide can also be suitably used.
[0066]
These colorants are preferably added since it is easy to distinguish an image area from a non-image area after image formation. The added amount is 0.01 to 10% by mass with respect to the total solid content of the photosensitive layer coating solution.
[0067]
In the present invention, a small amount of a thermal polymerization inhibitor is added to prevent unnecessary thermal polymerization of a radically polymerizable compound having an ethylenically unsaturated double bond during preparation or storage of the photosensitive layer coating solution. It is desirable to do. Suitable thermal polymerization inhibitors include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4'-thiobis (3-methyl-6-t-butylphenol ), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), N-nitroso-N-phenylhydroxylamine aluminum salt and the like. The addition amount of the thermal polymerization inhibitor is preferably about 0.01% by mass to about 5% by mass with respect to the mass of the entire composition. If necessary, a higher fatty acid derivative such as behenic acid or behenic acid amide may be added to prevent polymerization inhibition due to oxygen, and it may be unevenly distributed on the surface of the photosensitive layer in the course of drying after coating. . The amount of the higher fatty acid derivative added is preferably about 0.1% by mass to about 10% by mass of the total composition.
[0068]
Further, in the photosensitive layer coating solution, nonionic surfactants as described in JP-A-62-251740 and JP-A-3-208514 are disclosed in order to broaden the processing stability against development conditions. Amphoteric surfactants such as those described in JP-A-59-121044 and JP-A-4-13149 can be added.
[0069]
Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether and the like.
[0070]
Specific examples of amphoteric surfactants include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine, N-tetradecyl-N, N- Examples include betaine type (for example, trade name Amorgen K, manufactured by Dai-ichi Kogyo Co., Ltd.).
[0071]
The proportion of the nonionic surfactant and amphoteric surfactant in the photosensitive layer coating solution is preferably 0.05 to 15% by mass, more preferably 0.1 to 5% by mass. In addition, additives such as an adhesion improver, a development improver, an ultraviolet absorber, and a slipping agent can be suitably blended depending on the purpose.
[0072]
Furthermore, in the photosensitive layer coating solution according to the present invention, a plasticizer is added as needed to impart flexibility of the coating film. For example, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate and the like are used.
[0073]
In order to produce the lithographic printing plate precursor according to the invention, the above-mentioned components necessary for the photosensitive layer coating solution are usually dissolved in a solvent and coated on a suitable support. Solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyllactone, toluene, water, and the like. However, it is not limited to this. These solvents are used alone or in combination. The concentration of the above components (total solid content including additives) in the solvent is preferably 1 to 50% by mass.
[0074]
The coating amount (solid content) of the photosensitive layer on the support obtained after coating and drying varies depending on the application, but generally speaking, it is 0.5 to 5.0 g / m for lithographic printing plate precursors. ² Is preferred. As the coating amount decreases, the apparent sensitivity increases, but the film properties of the photosensitive layer that performs the image recording function decrease.
Various methods can be used as the coating method, and examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.
[0075]
In the photosensitive layer coating solution according to the present invention, a surfactant for improving coating properties, for example, a fluorine-based surfactant described in JP-A-62-170950 can be added. . A preferable addition amount is 0.01 to 1% by mass, and more preferably 0.05 to 0.5% by mass in the material solid content of the entire photosensitive layer.
[0076]
[Support]
The support that can be used in the lithographic printing plate precursor according to the present invention is not particularly limited as long as it is a dimensionally stable plate-like material. For example, paper, plastic (for example, polyethylene, polypropylene, polystyrene, etc.) is laminated. Paper, metal plates (eg, aluminum, zinc, copper, etc.), plastic films (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, Polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic film on which a metal as described above is laminated or vapor-deposited.
[0077]
As the support used in the present invention, it is preferable to use an aluminum plate that is lightweight and excellent in surface treatment, workability, and corrosion resistance. As the aluminum material used for this purpose, JIS 1050 material, JIS 1100 material, JIS 1070 material, Al-Mg alloy, Al-Mn alloy, Al-Mn-Mg alloy, Al-Zr alloy. Examples include Al—Mg—Si based alloys.
[0078]
A suitable aluminum plate is a pure aluminum plate or an alloy plate as described above which contains aluminum as a main component and contains a trace amount of foreign elements, and may be a plastic film on which aluminum is laminated or vapor-deposited. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. Content of the different element in an alloy is 10 mass% or less. As the aluminum plate, pure aluminum is preferable. However, since pure aluminum is difficult to manufacture in terms of refining technology, it may contain a slightly different element. Thus, the composition of the aluminum plate is not specified, and conventionally known and used aluminum plates can be appropriately used. The thickness of the aluminum plate is preferably about 0.1 to 0.6 mm, more preferably 0.15 to 0.4 mm, and particularly preferably 0.2 to 0.3 mm.
[0079]
Prior to roughening the aluminum plate, a degreasing treatment with, for example, a surfactant, an organic solvent, or an alkaline aqueous solution for removing rolling oil on the surface is performed as desired. The surface roughening treatment of the aluminum plate is performed by various methods. For example, a method of mechanically roughening, a method of electrochemically dissolving and roughening a surface, and a method of selectively dissolving a surface chemically. This is done by the method of As the mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in hydrochloric acid or nitric acid electrolyte.
[0080]
The roughened aluminum plate is subjected to alkali etching treatment and neutralization treatment as necessary, and then subjected to anodization treatment to enhance the surface water retention and wear resistance as desired. The amount of anodized film by anodization is 1.0 g / m. ² The above is preferable. The amount of anodized film is 1.0 g / m ² If it is less than 1, the printing durability is insufficient, or when used as a lithographic printing plate, the non-image area is likely to be scratched, and so-called “scratches that cause ink to adhere to the scratched area during printing. “Stain” may easily occur. After the anodizing treatment, the surface of the aluminum is subjected to a hydrophilic treatment as necessary.
[0081]
In addition, such an aluminum support can be used after anodizing treatment, treatment with an organic acid or a salt thereof, or application of an undercoat layer coated with a photosensitive layer.
[0082]
An intermediate layer for improving the adhesion between the support and the photosensitive layer may be provided. In order to improve the adhesion, the intermediate layer is generally composed of a diazo resin, a phosphoric acid compound adsorbed on aluminum, for example. The thickness of the intermediate layer is arbitrary, and it must be a thickness capable of performing a uniform bond forming reaction with the upper photosensitive layer when exposed. Usually about 1 to 100 mg / m dry solid ² The application rate of 5-40 mg / m is good ² Is particularly good. The ratio of the diazo resin used in the intermediate layer is 30 to 100%, preferably 60 to 100%.
[0083]
After the above treatment or undercoating is applied to the support surface, a back coat is provided on the back surface of the support as necessary. As such a back coat, a coating layer made of a metal oxide obtained by hydrolysis and polycondensation of an organic polymer compound described in JP-A-5-45885 and an organic or inorganic metal compound described in JP-A-6-35174 is used. Preferably used.
[0084]
A preferable characteristic as a support for a lithographic printing plate is a center line average roughness of 0.10 to 1.2 μm. If it is less than 0.10 μm, the adhesion with the photosensitive layer is lowered, resulting in a significant reduction in printing durability. When it is larger than 1.2 μm, the stain property at the time of printing deteriorates. Further, the color density of the support is 0.15 to 0.65 as the reflection density value. If the density is whiter than 0.15, the halation at the time of image exposure is too strong, which hinders image formation, and 0.65. In the case of a blacker color, it is difficult to see the image in the plate inspection after development, and the plate inspection is extremely poor.
[0085]
As described above, the above-mentioned photosensitive layer, surface protective layer, and other arbitrary layers such as an intermediate layer and a back coat layer are formed on the support obtained by performing the predetermined treatment. By doing so, the planographic printing plate precursor of the present invention can be obtained.
The planographic printing plate precursor of the present invention is image-recorded by an infrared laser. In the present invention, image exposure is preferably performed by a solid-state laser and a semiconductor laser that emit infrared rays having a wavelength of 760 nm to 1200 nm. The laser output is preferably 100 mW or more, and a multi-beam laser device is preferably used in order to shorten the exposure time. The exposure time per pixel is preferably within 20 μsec. The energy applied to the recording material is 10 to 300 mJ / cm. ² It is preferable that If the exposure energy is too low, the curing of the photosensitive layer may not proceed sufficiently, and if the exposure energy is too high, the photosensitive layer may be laser ablated and the image may be damaged.
[0086]
The exposure in the present invention is performed by overlapping the light beams of the light sources. Overlap means that the sub-scanning pitch width is smaller than the beam diameter. The overlap can be expressed quantitatively by FWHM / sub-scanning pitch width (overlap coefficient), for example, when the beam diameter is expressed by the half width (FWHM) of the beam intensity. In the present invention, the overlap coefficient is preferably 0.1 or more.
[0087]
The scanning method of the light source of the exposure apparatus used in the present invention is not particularly limited, and a cylindrical outer surface scanning method, a cylindrical inner surface scanning method, a planar scanning method, or the like can be used. The channel of the light source may be a single channel or a multi-channel, but in the case of a cylindrical outer surface system, a multi-channel is preferably used.
[0088]
As the developer and replenisher used for the development and plate making of the lithographic printing plate precursor according to the invention, conventionally known alkaline aqueous solutions can be used.
For example, sodium silicate, potassium, tribasic sodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, sodium carbonate, potassium, ammonium, sodium bicarbonate, potassium, Examples include inorganic alkali salts such as ammonium, sodium borate, potassium, ammonium, sodium hydroxide, ammonium, potassium, and lithium. Moreover, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, Organic alkali agents such as ethyleneimine, ethylenediamine, and pyridine are also used. These alkali agents are used alone or in combination of two or more.
[0089]
Among these alkali agents, particularly preferred developers are aqueous silicate solutions such as sodium silicate and potassium silicate. The reason is silicon oxide SiO which is a component of silicate. ₂ And alkali metal oxide M ₂ This is because the developability can be adjusted by the ratio and concentration of O. For example, alkali metal silicates as described in JP-A No. 54-62004 and JP-B No. 57-7427 are effective. Used for.
[0090]
When developing using an automatic developing machine, an aqueous solution (replenisher) having a higher alkali strength than the developer is added to the developer, so that a large amount of PS can be obtained without replacing the developer in the developer tank for a long time. It is known that plates can be processed. This replenishment method is also preferably applied in the present invention. Various surfactants and organic solvents can be added to the developer and replenisher as necessary for the purpose of promoting and suppressing developability, dispersing development residue, and improving ink affinity of the printing plate image area.
[0091]
Preferred surfactants include anionic, cationic, nonionic and amphoteric surfactants. If necessary, the developer and replenisher may contain reducing agents such as hydroquinone, resorcin, sulfurous acid, bisulfite, and other inorganic acids such as sodium salts and potassium salts, organic carboxylic acids, antifoaming agents, and hard water softeners. It can also be added.
[0092]
The lithographic printing plate developed using the developer and the replenisher is post-treated with a desensitizing solution containing washing water, a rinsing solution containing a surfactant and the like, gum arabic and a starch derivative. In the case of using the printing plate obtained by making the planographic printing plate precursor of the present invention by the above method, these treatments can be used in various combinations.
[0093]
In recent years, automatic developing machines for printing plates have been widely used in the plate making and printing industries in order to rationalize and standardize plate making operations. The lithographic printing plate obtained by the present invention can also be processed by this automatic processor. This automatic developing machine is generally composed of a developing section and a post-processing section. It consists of an apparatus that transports the printing plate material, each processing solution tank, and a spray device. Each processing solution is sprayed from a spray nozzle for development processing. In addition, recently, a method is also known in which a printing plate material is immersed and conveyed in a processing liquid tank filled with a processing liquid by a submerged guide roll or the like. In such automatic processing, each processing solution can be processed while being supplemented with a replenisher according to the processing amount, operating time, and the like. In addition, the electrical conductivity can be detected by a sensor and replenished automatically. In addition, a so-called disposable processing method in which processing is performed with a substantially unused processing solution can also be applied. According to this method, there is no concern about deterioration in developability due to carbon dioxide gas over time or reduction in printing durability due to the developer, and therefore the method according to the present invention is suitable for any of these automatic processors. Can be applied.
[0094]
The lithographic printing plate obtained as described above can be subjected to a printing process after applying a desensitized gum if desired. However, if it is desired to obtain a lithographic printing plate with a higher printing durability, a burning treatment is performed. Is given.
In the case of burning a lithographic printing plate, before burning, an adjustment as described in JP-B-61-2518, JP-A-55-28062, JP-A-62-31859, JP-A-61-159655 is used. It is preferable to treat with a surface liquid.
[0095]
As its method, with a sponge or absorbent cotton soaked with the surface-adjusting liquid, it is applied onto a lithographic printing plate, or a method in which the printing plate is immersed and applied in a vat filled with the surface-adjusting liquid, Application by an automatic coater is applied. Further, it is more preferable to make the coating amount uniform with a squeegee or a squeegee roller after coating. The coating amount of the surface conditioning liquid is generally 0.03 to 0.8 g / m. ² (Dry mass) is appropriate.
[0096]
The lithographic printing plate coated with the surface conditioning liquid is dried if necessary and then heated to a high temperature with a burning processor (for example, burning processor BP-1300 sold by Fuji Photo Film Co., Ltd.). The In this case, the heating temperature and time are in the range of 180 to 300 ° C. and preferably in the range of 1 to 20 minutes, although depending on the type of components forming the image.
[0097]
The burned lithographic printing plate can be subjected to conventional treatments such as washing and gumming as needed, but a surface-conditioning solution containing a water-soluble polymer compound or the like is used. In such a case, a so-called desensitizing treatment such as gumming can be omitted.
[0098]
The lithographic printing plate obtained by such treatment is applied to an offset printing machine or the like and used for printing a large number of sheets.
[0099]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
[Examples 1-3, Comparative Examples 1-3]
[Create support]
A 0.30 mm thick aluminum web (material 1050) was degreased with a 10% sodium aluminate aqueous solution at 50 ° C. for 30 seconds to remove the rolling oil on the surface, and neutralized with a 30% sulfuric acid aqueous solution at 50 ° C. for 30 seconds. A smut removal treatment was performed.
[0100]
Next, the adhesion between the support and the recording layer was improved, and a graining treatment was performed. An aqueous solution containing 1% hydrochloric acid and 0.5% aluminum nitrate is kept at 45 ° C., and the current density is 20 A / dm by an indirect power feeding cell while flowing the aluminum web into the aqueous solution. ² , Anode side electricity quantity 240C / dm with alternating waveform with duty ratio 1: 1 ² Electrolytic graining was performed by giving Thereafter, etching treatment was performed with a 10% sodium aluminate aqueous solution at 50 ° C. for 30 seconds, and neutralization and smut removal treatment were performed with a 30% sulfuric acid aqueous solution at 50 ° C. for 30 seconds.
[0101]
Furthermore, a 20% sulfuric acid aqueous solution was used as the electrolyte at 35 ° C., and the aluminum web was carried into the electrolyte while the indirect power feeding cell was used to provide 14 A / dm. ² 2.5 g / m by electrolytic treatment with direct current ² An anodic oxide film was prepared. The following undercoat liquid was applied to the prepared aluminum support with a wire bar, and dried at 90 ° C. for 30 seconds using a hot air dryer. The amount of clothes after drying is 20mg / m ² Met.
[0102]
[undercoat]
Next, the following undercoat liquid was applied to this aluminum support with a wire bar, and dried at 90 ° C. for 30 seconds using a hot air drying apparatus. The amount of clothes after drying is 10mg / m ² Met.
[0103]
<Undercoat liquid>
・ 0.4g of 2-methacryloyloxyethyl phosphoric acid
・ Methanol 20g
・ Ion exchange water 80g
[0104]
[Photosensitive layer]
First, a polymer compound (P-1) to be added as a binder to the following photosensitive layer coating solution was synthesized.
<Synthesis of polymer compound (P-1)>
A 1000 ml flask was charged with 70 g of N, N-dimethylacetamide and heated to 70 ° C. under a nitrogen stream. Compound (A-1) 33.5 g, methacrylamide 6.8 g, methyl methacrylate 12.0 g, methacrylic acid 6.9 g, V-59 (manufactured by Wako Pure Chemical Industries) 0.538 g of N, N-dimethyl shown below A solution of 70 g of acetamide was added dropwise over 2.5 hours. After completion of dropping, the mixture was heated to 90 ° C. and further stirred for 2 hours. After cooling the reaction solution to room temperature, it was poured into 3.5 L of water to precipitate a polymer compound. The precipitated polymer compound was collected by filtration, washed with water and dried to obtain 48.5 g of a polymer compound. As a result of measuring the weight average molecular weight of the obtained polymer compound by gel permeation chromatography (GPC) using polystyrene as a standard substance, it was 124,000. Moreover, when the acid value was calculated | required by titration, it was 1.30 meq / g (calculated value 1.35 meq / g), and it was confirmed that superposition | polymerization was performed normally.
[0105]
In a 200 ml three-necked flask, 26.0 g of the resulting polymer compound and 0.1 p-methoxyphenol were placed and dissolved in 60 g of N, N-dimethylacetamide. After dissolution, the mixture was cooled in an ice bath containing ice water. After the temperature of the mixture became 5 ° C. or lower, 30.4 g of 1,8-diazabicyclo [5.4.0] -7-undecene (DBU) was added dropwise over 1 hour using a dropping funnel. After completion of dropping, the ice bath was removed and the mixture was further stirred for 8 hours. The reaction solution was poured into 2 L of water in which 17 ml of concentrated hydrochloric acid was dissolved to precipitate the polymer compound (P-1). The precipitated polymer compound was collected by filtration, washed with water and dried to obtain 18.2 g of the polymer compound (P-1). When H-NMR of the obtained polymer compound (P-1) was measured, it was confirmed that 100% of the side chain groups derived from the compound (A-1) were converted to ethylene methacrylate groups. The weight average molecular weight measured by gel permeation chromatography (GPC) using polystyrene as a standard substance was 114,000. Furthermore, when the acid value was determined by titration, it was 0.9 meq / g (calculated value 0.8 meq / g).
[0106]
[Chemical 3]

[0107]
Next, the following photosensitive layer coating solution was prepared, applied to the undercoated aluminum plate using a wire bar, and dried at 120 ° C. for 45 seconds with a hot air dryer to form a photosensitive layer. The coating amount after drying is 2.0 g / m ² Met.
[0108]
<Photosensitive layer coating solution>
・ Infrared absorber having the structure shown below 0.10 g
-Radical generator having the structure shown below 0.15 g
・ Dipentaerythritol hexaacrylate 1.0g
-1.0 g of polymer compound (P-1) obtained above
・ Crystal Violet 0.06g
・ Fluorine-based surfactant 0.01g
(Megafuck F-176, manufactured by Dainippon Ink & Chemicals, Inc.)
・ Stearoylmethylamide 0.02g
・ Methyl ethyl ketone 14.0g
・ Methanol 6.5g
・ 1-methoxy-2-propanol 10.0g
[0109]
[Formula 4]

[0110]
Further, the following overcoat layer coating solution was applied using a slide hopper, and dried at 120 ° C. for 75 seconds with a hot-air dryer to obtain a lithographic printing plate precursor according to the present invention. The film weight of the overcoat layer after coating and drying (g / m ² ) Is shown in Table 1.
[0111]
<Overcoat layer coating solution>
・ Polyvinyl alcohol 2.5g
(PVA105: manufactured by Kuraray Co., Ltd., saponification degree 98.5%, polymerization degree 500)
・ Polyvinylpyrrolidone 0.5g
(K30, Tokyo Chemical Industry Co., Ltd. molecular weight 40,000)
・ Nonionic surfactant 0.05g
(EMAREX NP-10 manufactured by Nippon Emulsion Co., Ltd.)
・ Ion-exchanged water 96.95g
[0112]
[Evaluation of sensitivity and developability]
The lithographic printing plate precursor obtained as described above was used to draw a test pattern in the form of an image by changing the exposure energy with a Trend setter 3244 manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser.
Next, the developer DV-2 (diluted to pH 12.0 (25 ° C.)) is introduced into an automatic processor LP-940H manufactured by Fuji Photo Film Co., Ltd., and the lithographic printing plate precursor is conveyed. The developer immersion time necessary for cutting off the image area of the printing plate was measured by changing the speed. At this time, the exposure energy was sufficiently cured by the previous image drawing, and the exposure energy at which the image was formed was measured and defined as sensitivity. The smaller the value, the higher the sensitivity. The results of sensitivity and time required for development are shown in Table 1.
[0113]
[Table 1]

[0114]
According to Table 1, the film weight of the overcoat layer is 0.05 g / m. ² 1.0 g / m ² Any of the lithographic printing plate precursors of the present invention prepared as described below, while ensuring the effect of improving the sensitivity, which is the original purpose of the overcoat layer, does not include complicated steps such as pre-washing. It was confirmed that the non-image area was removed by the time development processing.
On the other hand, the lithographic printing plate precursor of Comparative Example 1 without an overcoat layer has a short development time but is inferior in sensitivity. The lithographic printing plate precursors of Comparative Examples 2 and 3 have excellent sensitivity, Since the film weight of the coat layer was large, it was found that development required time compared to the examples.
[0115]
[Examples 4 to 6, Comparative Examples 4 and 5]
Polyvinyl alcohol (PVA105: manufactured by Kuraray Co., Ltd., saponification degree 98.5%, polymerization degree 500) in the overcoat layer in Examples 1 to 3 was changed to itaconic acid-modified polyvinyl alcohol (KM-118: Kuraray Co., Ltd.). Except for changing the coating amount of the overcoat layer to that described in Table 2 below, the same as in Examples 1 to 3, except that the saponification degree is 95.5 to 98.5%. A lithographic printing plate precursor was prepared and evaluated in the same manner. The results are also shown in Table 2.
[0116]
[Table 2]

[0117]
According to Table 2, the film weight of the overcoat layer was 0.05 g / m. ² 1.0 g / m ² Any of the lithographic printing plate precursors of the present invention prepared as described below, while ensuring the effect of improving the sensitivity, which is the original purpose of the overcoat layer, does not include complicated steps such as pre-washing. It was confirmed that the non-image area was removed by the time development processing. Moreover, it turned out that the developability is improving also compared with Examples 1-3.
On the other hand, it was found that the lithographic printing plate precursors of Comparative Examples 4 and 5 in which the film weight of the overcoat layer was 1.0 or more were excellent in sensitivity, but required more time for development than in Examples.
[0118]
【The invention's effect】
According to the present invention, a negative lithographic printing plate that can be recorded directly from digital data such as a computer by recording using a solid-state laser and a semiconductor laser that emits infrared rays, and has high sensitivity and excellent developability. You can get the original version.

Claims (2)

A photosensitive layer containing (A) an infrared absorbent, (B) a radical generator, and (C) a radical polymerizable compound on the support, and causing a curing reaction by infrared irradiation;
Film weight after drying of, 0.05 g / ^{m 2} or more, and 1.0 g / ^{m 2} or less of the overcoat layer,
A lithographic printing plate precursor that is sequentially provided. The lithographic printing plate precursor according to claim 1, wherein the overcoat layer contains at least one of polyvinyl alcohol and acid-modified polyvinyl alcohol.