JP2005007655A - Original printing plate for lithographic printing plate and method for lithographic printing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an original printing plate for a lithographic printing plate capable of direct plate manufacturing by infrared laser scanning and having both press developing properties and plate wear at a high level, and a method for lithographic printing using it. <P>SOLUTION: The original printing plate for the lithographic printing plate comprises a sub-layer comprising a polymerizable compound and a hydrophilic binder polymer and an upper layer comprising a polymerizable compound and a hydrophobic binder polymer on a substrate, comprises an infrared absorbent and a polymerization initiator in at least either one layer of the sub-layer and the upper layer, can be recorded by irradiation of infrared rays, and can be removed with a printing ink and/or a dampening water. The method for lithographic printing comprises exposing the original printing plate for the lithographic printing plate with the infrared rays into an image-like way, feeding an oily ink and an aqueous component to remove unexposed parts of an image recording layer, and printing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００５８】
一般式（ｉ）中、Ｘ^１は、水素原子、ハロゲン原子、−ＮＰｈ_２、Ｘ^２−Ｌ^１又は以下に示す基を表す。
【００５９】
【化２】

【００６０】
ここで、Ｘ^２は酸素原子、窒素原子、又は硫黄原子を示し、Ｌ^１は、炭素原子数１〜１２の炭化水素基、ヘテロ原子を有する芳香族環、又はヘテロ原子を含む炭素原子数１〜１２の炭化水素基を示す。なお、ここでヘテロ原子とは、Ｎ、Ｓ、Ｏ、ハロゲン原子、Ｓｅを示す。Ｘａ⁻は後述するＺａ⁻と同様に定義され、Ｒ^ａは、水素原子、アルキル基、アリール基、置換又は無置換のアミノ基、ハロゲン原子より選択される置換基を表す。
【００６１】
Ｒ^１及び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。記録層塗布液の保存安定性から、Ｒ^１及び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、更に、Ｒ^１とＲ^２とは互いに結合し、５員環又は６員環を形成していることが特に好ましい。
【００６２】
Ａｒ^１、Ａｒ^２は、それぞれ同じでも異なっていてもよく、置換基を有していてもよ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、ベンゼン環及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よく、硫黄原子又は炭素原子数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よく、置換基を有していてもよい炭素原子数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及びＲ^８は、それぞれ同じでも異なっていてもよく、水素原子又は炭素原子数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、Ｚａ⁻は、対アニオンを示す。ただし、一般式（ｉ）で示されるシアニン色素が、その構造内にアニオン性の置換基を有し、電荷の中和が必要ない場合にはＺａ⁻は必要ない。好ましいＺａ⁻は、記録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、及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、ヘキサフルオロホスフェートイオン、及びアリールスルホン酸イオンである。
【００６３】
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公報の段落番号［００１７］から［００１９］に記載されたものを挙げることができる。
また、特に好ましい他の例として、特開２００２−２７８０５７号公報に記載の特定インドレニンシアニン色素を挙げることができる。
【００６４】
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。
【００６５】
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。
【００６６】
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。
【００６７】
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。この範囲で、顔料分散物の画像記録層塗布液中での良好な安定性と画像記録層の良好な均一性が得られる。
【００６８】
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。
【００６９】
これらの赤外線吸収剤は、画像記録層下層及び上層の少なくともいずれかの層に含有される。前記重合性化合物と共にマイクロカプセルに内包して含有させることもできる。赤外線吸収剤の画像記録層への添加量としては、添加された層の波長７６０ｎｍ〜１２００ｎｍの範囲における極大吸収波長での吸光度が、反射測定法で０．３〜１．２の範囲にあるように添加する。好ましくは、０．４〜１．１の範囲である。この範囲内で良好な画像部の膜強度が得られる。
吸光度の測定は常法により行うことができる。測定方法としては、例えば、アルミニウム等の反射性の支持体上に、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画像記録層を形成し、反射濃度を光学濃度計で測定する方法、積分球を用いた反射法により分光光度計で測定する方法等が挙げられる。
【００７０】
（重合開始剤）
本発明に用いることができる重合開始剤は、熱、光又はその両方のエネルギーにより、ラジカルを発生させ、重合性化合物の硬化反応を開始、進行させる。このための重合開始剤としては、熱により分解してラジカルを発生する熱分解型のラジカル発生剤が有用である。このようなラジカル発生剤は前述した赤外線吸収剤と併用することで、赤外線レーザーを照射した際に赤外線吸収剤が発熱し、その熱によりラジカルを発生するものであり、これらの組合せによりヒートモード記録が可能となる。
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。以下に、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。本発明において特に好適に用いられるオニウム塩は、下記一般式（Ｉ）〜（ＩＩＩ）で表されるオニウム塩である。
【００７１】
【化３】

【００７２】
式（Ｉ）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、ヘキサフルオロホスフェートイオン、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。
【００７３】
式（ＩＩ）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。
【００７４】
式（ＩＩＩ）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。
【００７５】
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、特開２００１−３４３７４２号、特開２００２−１４８７９０号の公報に記載されたもの等を挙げることができる。以下に、本発明において、好適に用いることのできる一般式（Ｉ）で示されるオニウム塩（［ＯＩ−１］〜［ＯＩ−１０］）、一般式（ＩＩ）で示されるオニウム塩（［ＯＮ−１］〜［ＯＮ−５］）、及び一般式（ＩＩＩ）で示されるオニウム塩（［ＯＳ−１］〜［ＯＳ−１０］）の具体例を挙げるが、これらに限定されるものではない。
【００７６】
【化４】

【００７７】
【化５】

【００７８】
【化６】

【００７９】
【化７】

【００８０】
【化８】

【００８１】
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い。より好ましくは、極大吸収波長が３６０ｎｍ以下であり、最も好ましくは３００ｎｍ以下である。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。
【００８２】
これらの重合開始剤は、画像記録層下層及び上層のうち、赤外線吸収剤が含有されている層に含有される。含有量としては、前記赤外線吸収剤に対して５より大きい質量比であることが好ましい。該質量比は、５より大きく１０より小さいことがより好ましく、５より大きく８より小さいことが特に好ましい。この範囲内で、良好な感度と耐刷性が得られる。
これらの重合開始剤は、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、これらの重合開始剤は、赤外線吸収剤を含まない層、又は画像記録層の他に別の層を設け、そこにも添加することができる。
【００８３】
（その他の添加剤）
本発明の画像記録層下層及び上層には、上記の成分以外の添加剤、例えば、界面活性剤、着色剤、焼き出し剤、重合禁止剤、高級脂肪酸誘導体、可塑剤、無機微粒子、低分子親水性化合物等を必要に応じて含有させることができる。かかる添加剤は、画像記録層に分子分散状に添加することもできるが、前記重合性化合物と共にマイクロカプセルに内包して添加することもできる。
【００８４】
＜界面活性剤＞
本発明において、画像記録層の下層及び／又は上層には、印刷開始時の機上現像性を促進させるため、及び、塗布面状を向上させるために界面活性剤を用いることができる。界面活性剤としては、ノニオン界面活性剤、アニオン界面活性剤、カチオン界面活性剤、両性界面活性剤、フッ素系界面活性剤等が挙げられる。界面活性剤は、単独で用いてもよく、２種以上を組み合わせて用いてもよい。
【００８５】
本発明に用いられるノニオン界面活性剤は、特に限定されず、従来公知のものを用いることができる。例えば、ポリオキシエチレンアルキルエーテル類、ポリオキシエチレンアルキルフェニルエーテル類、ポリオキシエチレンポリスチリルフェニルエーテル類、ポリオキシエチレンポリオキシプロピレンアルキルエーテル類、グリセリン脂肪酸部分エステル類、ソルビタン脂肪酸部分エステル類、ペンタエリスリトール脂肪酸部分エステル類、プロピレングリコールモノ脂肪酸エステル類、ショ糖脂肪酸部分エステル類、ポリオキシエチレンソルビタン脂肪酸部分エステル類、ポリオキシエチレンソルビトール脂肪酸部分エステル類、ポリエチレングリコール脂肪酸エステル類、ポリグリセリン脂肪酸部分エステル類、ポリオキシエチレン化ひまし油類、ポリオキシエチレングリセリン脂肪酸部分エステル類、脂肪酸ジエタノールアミド類、Ｎ，Ｎ−ビス−２−ヒドロキシアルキルアミン類、ポリオキシエチレンアルキルアミン、トリエタノールアミン脂肪酸エステル、トリアルキルアミンオキシド、ポリエチレングリコール、ポリエチレングリコールとポリプロピレングリコールの共重合体が挙げられる。
【００８６】
本発明に用いられるアニオン界面活性剤は、特に限定されず、従来公知のものを用いることができる。例えば、脂肪酸塩類、アビエチン酸塩類、ヒドロキシアルカンスルホン酸塩類、アルカンスルホン酸塩類、ジアルキルスルホ琥珀酸エステル塩類、直鎖アルキルベンゼンスルホン酸塩類、分岐鎖アルキルベンゼンスルホン酸塩類、アルキルナフタレンスルホン酸塩類、アルキルフェノキシポリオキシエチレンプロピルスルホン酸塩類、ポリオキシエチレンアルキルスルホフェニルエーテル塩類、Ｎ−メチル−Ｎ−オレイルタウリンナトリウム塩、Ｎ−アルキルスルホコハク酸モノアミド二ナトリウム塩、石油スルホン酸塩類、硫酸化牛脂油、脂肪酸アルキルエステルの硫酸エステル塩類、アルキル硫酸エステル塩類、ポリオキシエチレンアルキルエーテル硫酸エステル塩類、脂肪酸モノグリセリド硫酸エステル塩類、ポリオキシエチレンアルキルフェニルエーテル硫酸エステル塩類、ポリオキシエチレンスチリルフェニルエーテル硫酸エステル塩類、アルキルリン酸エステル塩類、ポリオキシエチレンアルキルエーテルリン酸エステル塩類、ポリオキシエチレンアルキルフェニルエーテルリン酸エステル塩類、スチレン／無水マレイン酸共重合物の部分けん化物類、オレフィン／無水マレイン酸共重合物の部分けん化物類、ナフタレンスルホン酸塩ホルマリン縮合物類が挙げられる。
【００８７】
本発明に用いられるカチオン界面活性剤は、特に限定されず、従来公知のものを用いることができる。例えば、アルキルアミン塩類、第四級アンモニウム塩類、ポリオキシエチレンアルキルアミン塩類、ポリエチレンポリアミン誘導体が挙げられる。
本発明に用いられる両性界面活性剤は、特に限定されず、従来公知のものを用いることができる。例えば、カルボキシベタイン類、アミノカルボン酸類、スルホベタイン類、アミノ硫酸エステル類、イミタゾリン類が挙げられる。
【００８８】
なお、上記界面活性剤の中で、「ポリオキシエチレン」とあるものは、ポリオキシメチレン、ポリオキシプロピレン、ポリオキシブチレン等の「ポリオキシアルキレン」に読み替えることもでき、本発明においては、それらの界面活性剤も用いることができる。
【００８９】
更に好ましい界面活性剤としては、分子内にパーフルオロアルキル基を含有するフッ素系界面活性剤が挙げられる。このようなフッ素系界面活性剤としては、例えば、パーフルオロアルキルカルボン酸塩、パーフルオロアルキルスルホン酸塩、パーフルオロアルキルリン酸エステル等のアニオン型；パーフルオロアルキルベタイン等の両性型；パーフルオロアルキルトリメチルアンモニウム塩等のカチオン型；パーフルオロアルキルアミンオキサイド、パーフルオロアルキルエチレンオキシド付加物、パーフルオロアルキル基及び親水性基を含有するオリゴマー、パーフルオロアルキル基及び親油性基を含有するオリゴマー、パーフルオロアルキル基、親水性基及び親油性基を含有するオリゴマー、パーフルオロアルキル基及び親油性基を含有するウレタン等のノニオン型が挙げられる。また、特開昭６２−１７０９５０号、同６２−２２６１４３号及び同６０−１６８１４４号の各公報に記載されているフッ素系界面活性剤も好適に挙げられる。
【００９０】
界面活性剤は、単独で又は２種以上を組み合わせて用いることができる。
界面活性剤は、画像記録層の下層及び／又は上層に、０．００１〜１０質量％含有させることが好ましく、０．０１〜５質量％含有させることがより好ましい。
【００９１】
＜着色剤＞
本発明の画像記録層には、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号公報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、酸化チタン等の顔料も好適に用いることができる。
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、画像記録層の下層及び／又は上層中に、０．０１〜１０質量％の割合が好ましい。
【００９２】
＜焼き出し剤＞
本発明の画像記録層には、焼き出し画像生成のため、酸又はラジカルによって変色する化合物を添加することができる。このような化合物としては、例えばジフェニルメタン系、トリフェニルメタン系、チアジン系、オキサジン系、キサンテン系、アンスラキノン系、イミノキノン系、アゾ系、アゾメチン系等の各種色素が有効に用いられる。
【００９３】
具体例としては、ブリリアントグリーン、エチルバイオレット、メチルグリーン、クリスタルバイオレット、ベイシックフクシン、メチルバイオレット２Ｂ、キナルジンレッド、ローズベンガル、メタニルイエロー、チモールスルホフタレイン、キシレノールブルー、メチルオレンジ、パラメチルレッド、コンゴーフレッド、ベンゾプルプリン４Ｂ、α−ナフチルレッド、ナイルブルー２Ｂ、ナイルブルーＡ、メチルバイオレット、マラカイドグリーン、パラフクシン、ビクトリアピュアブルーＢＯＨ［保土ケ谷化学（株）製］、オイルブルー＃６０３［オリエント化学工業（株）製］、オイルピンク＃３１２［オリエント化学工業（株）製］、オイルレッド５Ｂ［オリエント化学工業（株）製］、オイルスカーレット＃３０８［オリエント化学工業（株）製］、オイルレッドＯＧ［オリエント化学工業（株）製］、オイルレッドＲＲ［オリエント化学工業（株）製］、オイルグリーン＃５０２［オリエント化学工業（株）製］、スピロンレッドＢＥＨスペシャル［保土ケ谷化学工業（株）製］、ｍ−クレゾールパープル、クレゾールレッド、ローダミンＢ、ローダミン６Ｇ、スルホローダミンＢ、オーラミン、４−ｐ−ジエチルアミノフェニルイミノナフトキノン、２−カルボキシアニリノ−４−ｐ−ジエチルアミノフェニルイミノナフトキノン、２−カルボキシステアリルアミノ−４−ｐ−Ｎ，Ｎ−ビス（ヒドロキシエチル）アミノ−フェニルイミノナフトキノン、１−フェニル−３−メチル−４−ｐ−ジエチルアミノフェニルイミノ−５−ピラゾロン、１−β−ナフチル−４−ｐ−ジエチルアミノフェニルイミノ−５−ピラゾロン等の染料やｐ，ｐ’，ｐ”−ヘキサメチルトリアミノトリフェニルメタン（ロイコクリスタルバイオレット）、Ｐｅｒｇａｓｃｒｉｐｔ Ｂｌｕｅ ＳＲＢ（チバガイギー社製）等のロイコ染料が挙げられる。
【００９４】
上記の他に、感熱紙や感圧紙用の素材として知られているロイコ染料も好適なものとして挙げられる。具体例としては、クリスタルバイオレットラクトン、マラカイトグリーンラクトン、ベンゾイルロイコメチレンブルー、２−（Ｎ−フェニル−Ｎ−メチルアミノ）−６−（Ｎ−ｐ−トリル−Ｎ−エチル）アミノ−フルオラン、２−アニリノ−３−メチル−６−（Ｎ−エチル−ｐ−トルイジノ）フルオラン、３，６−ジメトキシフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−５−メチル−７−（Ｎ，Ｎ−ジベンジルアミノ）−フルオラン、３−（Ｎ−シクロヘキシル−Ｎ−メチルアミノ）−６−メチル−７−アニリノフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−６−メチル−７−アニリノフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−６−メチル−７−キシリジノフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−６−メチルー７−クロロフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−６−メトキシ−７−アミノフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−７−（４−クロロアニリノ）フルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−７−クロロフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−７−ベンジルアミノフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−７，８−ベンゾフロオラン、３−（Ｎ，Ｎ−ジブチルアミノ）−６−メチル−７−アニリノフルオラン、３−（Ｎ，Ｎ−ジブチルアミノ）−６−メチル−７−キシリジノフルオラン、３−ピペリジノ−６−メチル−７−アニリノフルオラン、３−ピロリジノ−６−メチル−７−アニリノフルオラン、３，３−ビス（１−エチル−２−メチルインドール−３−イル）フタリド、３，３−ビス（１−ｎ−ブチル−２−メチルインドール−３−イル）フタリド、３，３−ビス（ｐ−ジメチルアミノフェニル）−６−ジメチルアミノフタリド、３−（４−ジエチルアミノ−２−エトキシフェニル）−３−（１−エチル−２−メチルインドール−３−イル）−４−ザフタリド、３−（４−ジエチルアミノフェニル）−３−（１−エチル−２−メチルインドール−３−イル）フタリド、などが挙げられる。
【００９５】
酸又はラジカルによって変色する染料は、画像記録層の下層及び／又は上層に、０．０１〜１０質量％の割合で添加することが好ましい。
【００９６】
＜熱重合防止剤＞
本発明の画像記録層には、画像記録層の製造中又は保存中において（Ｃ）重合性化合物の不要な熱重合を防止するために、少量の熱重合防止剤を添加するのが好ましい。
熱重合防止剤としては、例えば、ヒドロキノン、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が好適に挙げられる。
熱重合防止剤は、画像記録層の下層及び／又は上層に、約０．０１〜約５質量％含有させるのが好ましい。
【００９７】
＜高級脂肪酸誘導体等＞
本発明の画像記録層の上層には、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上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、上層の全固形分に対して、約０．１〜約１０質量％であるのが好ましい。
【００９８】
＜可塑剤＞
本発明の画像記録層は、機上現像性を向上させるために、可塑剤を含有してもよい。
可塑剤としては、例えば、ジメチルフタレート、ジエチルフタレート、ジブチルフタレート、ジイソブチルフタレート、ジオクチルフタレート、オクチルカプリルフタレート、ジシクロヘキシルフタレート、ジトリデシルフタレート、ブチルベンジルフタレート、ジイソデシルフタレート、ジアリルフタレート等のフタル酸エステル類；ジメチルグリコールフタレート、エチルフタリルエチルグリコレート、メチルフタリルエチルグリコレート、ブチルフタリルブチルグリコレート、トリエチレングリコールジカプリル酸エステル等のグリコールエステル類；トリクレジルホスフェート、トリフェニルホスフェート等のリン酸エステル類；ジイソブチルアジペート、ジオクチルアジペート、ジメチルセバケート、ジブチルセバケート、ジオクチルアゼレート、ジブチルマレエート等の脂肪族二塩基酸エステル類；ポリグリシジルメタクリレート、クエン酸トリエチル、グリセリントリアセチルエステル、ラウリン酸ブチル等が好適に挙げられる。
可塑剤は、画像記録層の下層及び／又は上層に、約３０質量％以下の割合で含有させることが好ましい。
【００９９】
＜無機微粒子＞
本発明の画像記録層は、表面粗面化による界面接着性の強化、画像部の硬化皮膜強度向上及び非画像部の機上現像性向上のために、無機微粒子を含有してもよい。
無機微粒子としては、例えば、シリカ、アルミナ、酸化マグネシウム、酸化チタン、炭酸マグネシウム、アルギン酸カルシウム又はこれらの混合物が好適に挙げられる。
無機微粒子は、平均粒径が５ｎｍ〜１０μｍであるのが好ましく、０．５μｍ〜３μｍであるのがより好ましい。上記範囲であると、画像記録層中に安定に分散して、画像記録層の膜強度を十分に保持し、印刷時の汚れを生じにくい親水性に優れる非画像部を形成することができる。
上述したような無機微粒子は、コロイダルシリカ分散物等の市販品として容易に入手することができる。
無機微粒子の含有量は、下層及び／又は上層の全固形分に対して、２０質量％以下であるのが好ましく、１０質量％以下であるのがより好ましい。
【０１００】
＜低分子親水性化合物＞
本発明の画像記録層は、機上現像性向上のため、親水性低分子化合物を含有しても良い。親水性低分子化合物としては、例えば、水溶性有機化合物としては、エチレングリコール、ジエチレングリコール、トリエチレングリコール、プロピレングリコール、ジプロピレングリコール、トリプロピレングリコール等のグリコール類及びそのエーテル又はエステル誘導体類、グリセリン、ペンタエリスリトール等のポリヒドロキシ類、トリエタノールアミン、ジエタノールアミンモノエタノールアミン等の有機アミン類及びその塩、トルエンスルホン酸、ベンゼンスルホン酸等の有機スルホン酸類及びその塩、フェニルホスホン酸等の有機ホスホン酸類及びその塩、酒石酸、シュウ酸、クエン酸、リンゴ酸、乳酸、グルコン酸、アミノ酸類等の有機カルボン酸類及びその塩等が上げられる。
【０１０１】
〔画像記録層の形成〕
本発明の画像記録層の下層及び上層は、必要な上記成分を溶剤に分散、又は溶かして塗布液を調製し、塗布される。ここで使用する溶剤としては、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。これらの溶剤は、単独又は混合して使用される。塗布液の固形分濃度は、好ましくは１〜５０質量％である。
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。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られる。
【０１０２】
下層及び上層の塗布量の好ましい範囲は、それぞれ、０．０５〜１０ｇ／ｍ^２、より好ましくは０．１〜５ｇ／ｍ^２、さらに好ましくは０．１〜３ｇ／ｍ^２である。また、下層／上層の塗布量の比率は、１／１００〜１００／１が好ましく、より好ましくは、１／５０〜５０／１、さらに好ましくは、１／１０〜１／１である。機上現像性と耐刷性のバランスの点からは、下層の塗布量が上層の塗布量よりも少ない方がより好ましい。
【０１０３】
〔支持体〕
本発明の平版印刷版原版に用いられる支持体は、特に限定されず、寸度的に安定な板状物であればよい。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）、上述した金属がラミネートされ又は蒸着された紙又はプラスチックフィルム等が挙げられる。好ましい支持体としては、ポリエステルフィルム及びアルミニウム板が挙げられる。中でも、寸法安定性がよく、比較的安価であるアルミニウム板が好ましい。
【０１０４】
アルミニウム板は、純アルミニウム板、アルミニウムを主成分とし、微量の異元素を含む合金板、又は、アルミニウムもしくはアルミニウム合金の薄膜にプラスチックがラミネートされているものである。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、チタン等がある。合金中の異元素の含有量は１０質量％以下であるのが好ましい。本発明においては、純アルミニウム板が好ましいが、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、わずかに異元素を含有するものでもよい。アルミニウム板は、その組成が特定されるものではなく、公知公用の素材のものを適宜利用することができる。
【０１０５】
支持体の厚さは０．１〜０．６ｍｍであるのが好ましく、０．１５〜０．４ｍｍであるのがより好ましく、０．２〜０．３ｍｍであるのが更に好ましい。
【０１０６】
アルミニウム板を使用するに先立ち、粗面化処理、陽極酸化処理等の表面処理を施すのが好ましい。表面処理により、親水性の向上及び画像記録層と支持体との密着性の確保が容易になる。アルミニウム板を粗面化処理するに先立ち、所望により、表面の圧延油を除去するための界面活性剤、有機溶剤、アルカリ性水溶液等による脱脂処理が行われる。
【０１０７】
アルミニウム板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、機械的粗面化処理、電気化学的粗面化処理（電気化学的に表面を溶解させる粗面化処理）、化学的粗面化処理（化学的に表面を選択溶解させる粗面化処理）が挙げられる。
機械的粗面化処理の方法としては、ボール研磨法、ブラシ研磨法、ブラスト研磨法、バフ研磨法等の公知の方法を用いることができる。
電気化学的粗面化処理の方法としては、例えば、塩酸、硝酸等の酸を含有する電解液中で交流又は直流により行う方法が挙げられる。また、特開昭５４−６３９０２号公報に記載されているような混合酸を用いる方法も挙げられる。
【０１０８】
粗面化処理されたアルミニウム板は、必要に応じて、水酸化カリウム、水酸化ナトリウム等の水溶液を用いてアルカリエッチング処理を施され、更に、中和処理された後、所望により、耐摩耗性を高めるために陽極酸化処理を施される。
【０１０９】
アルミニウム板の陽極酸化処理に用いられる電解質としては、多孔質酸化皮膜を形成させる種々の電解質の使用が可能である。一般的には、硫酸、塩酸、シュウ酸、クロム酸又はそれらの混酸が用いられる。それらの電解質の濃度は電解質の種類によって適宜決められる。
陽極酸化処理の条件は、用いられる電解質により種々変わるので一概に特定することはできないが、一般的には、電解質濃度１〜８０質量％溶液、液温５〜７０℃、電流密度５〜６０Ａ／ｄｍ^２、電圧１〜１００Ｖ、電解時間１０秒〜５分であるのが好ましい。形成される陽極酸化皮膜の量は、１．０〜５．０ｇ／ｍ^２であるのが好ましく、１．５〜４．０ｇ／ｍ^２であるのがより好ましい。この範囲で、良好な耐刷性と平版印刷版の非画像部の良好な耐傷性が得られる。
【０１１０】
陽極酸化処理を施した後、必要に応じて、アルミニウム板の表面に親水化処理を施す。親水化処理としては、米国特許第２，７１４，０６６号、同第３，１８１，４６１号、同第３，２８０，７３４号及び同第３，９０２，７３４号の各明細書に記載されているようなアルカリ金属シリケート法がある。この方法においては、支持体をケイ酸ナトリウム等の水溶液で浸せき処理し、又は電解処理する。そのほかに、特公昭３６−２２０６３号公報に記載されているフッ化ジルコン酸カリウムで処理する方法、米国特許第３，２７６，８６８号、同第４，１５３，４６１号及び同第４，６８９，２７２号の各明細書に記載されているようなポリビニルホスホン酸で処理する方法等が挙げられる。
【０１１１】
支持体は、中心線平均粗さが０．１０〜１．２μｍであるのが好ましい。この範囲で、画像記録層との良好な密着性、良好な耐刷性と良好な汚れ難さが得られる。
また、支持体の色濃度としては、反射濃度値として０．１５〜０．６５であるのが好ましい。この範囲で、画像露光時のハレーション防止による良好な画像形成性と現像後の良好な検版性が得られる。
【０１１２】
〔バックコート〕
支持体に表面処理を施した後、又は後述の下塗り層を形成させた後、必要に応じて、支持体の裏面にバックコートを設けることができる。
バックコートとしては、例えば、特開平５−４５８８５号公報に記載されている有機高分子化合物、特開平６−３５１７４号公報に記載されている有機金属化合物又は無機金属化合物を加水分解及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適に挙げられる。中でも、Ｓｉ（ＯＣＨ_３ ）_４ 、Ｓｉ（ＯＣ_２ Ｈ_５ ）_４ 、Ｓｉ（ＯＣ_３ Ｈ_７ ）_４ 、Ｓｉ（ＯＣ_４ Ｈ_９ ）_４ 等のケイ素のアルコキシ化合物を用いるのが、原料が安価で入手しやすい点で好ましい。
【０１１３】
〔下塗り層〕
本発明の平版印刷方法に用いられる本発明の平版印刷版原版においては、必要に応じて、画像記録層の下層と支持体との間に下塗り層を設けることができる。下塗り層が断熱層として機能することにより、赤外線レーザーによる露光により発生した熱が支持体に拡散せず、効率よく利用されるようになるため、高感度化が図れるという利点がある。また、未露光部においては、画像記録層の支持体からのはく離を生じやすくさせるため、機上現像性が向上する。
下塗り層としては、具体的には、特開平１０−２８２６７９号公報に記載されている付加重合可能なエチレン性二重結合反応基を有しているシランカップリング剤、エチレン性二重結合反応基を有しているリン化合物等が好適に挙げられる。
下塗り層の塗布量（固形分）は、０．１〜１００ｍｇ／ｍ^２ であるのが好ましく、３〜３０ｍｇ／ｍ^２ であるのがより好ましい。
【０１１４】
〔保護層〕
本発明の平版印刷方法に用いられる本発明の平版印刷版原版においては、画像記録層における傷等の発生防止、酸素遮断、高照度レーザー露光時のアブレーション防止のため、必要に応じて、画像記録層上層の上に保護層を設けることができる。
本発明においては、通常、露光を大気中で行うが、保護層は、画像記録層中で露光により生じる画像形成反応を阻害する大気中に存在する酸素、塩基性物質等の低分子化合物の画像記録層への混入を防止し、大気中での露光による画像形成反応の阻害を防止する。従って、保護層に望まれる特性は、酸素等の低分子化合物の透過性が低いことであり、更に、露光に用いられる光の透過性が良好で、画像記録層との密着性に優れ、かつ、露光後の機上現像処理工程で容易に除去することができるものであるのが好ましい。このような特性を有する保護層については、以前より種々検討がなされており、例えば、米国特許第３、４５８、３１１号明細書及び特開昭５５−４９７２９号公報に詳細に記載されている。
【０１１５】
保護層に用いられる材料としては、例えば、比較的、結晶性に優れる水溶性高分子化合物が挙げられる。具体的には、ポリビニルアルコール、ポリビニルピロリドン、酸性セルロース類、ゼラチン、アラビアゴム、ポリアクリル酸等の水溶性ポリマーが挙げられる。中でも、ポリビニルアルコール（ＰＶＡ）を主成分として用いると、酸素遮断性、現像除去性等の基本的な特性に対して最も良好な結果を与える。ポリビニルアルコールは、保護層に必要な酸素遮断性と水溶性を与えるための未置換ビニルアルコール単位を含有する限り、一部がエステル、エーテル又はアセタールで置換されていてもよく、一部が他の共重合成分を有していてもよい。
ポリビニルアルコールの具体例としては、７１〜１００％加水分解された分子量３００〜２４００の範囲のものが好適に挙げられる。具体的には、例えば、（株）クラレ製のＰＶＡ−１０５、ＰＶＡ−１１０、ＰＶＡ−１１７、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が挙げられる。
【０１１６】
保護層の成分（ＰＶＡの選択、添加剤の使用等）、塗布量等は、酸素遮断性及び現像除去性のほか、カブリ性、密着性、耐傷性等を考慮して適宜選択される。一般には、ＰＶＡの加水分解率が高いほど（即ち、保護層中の未置換ビニルアルコール単位含有率が高いほど）、また、膜厚が厚いほど、酸素遮断性が高くなり、感度の点で好ましい。また、製造時及び保存時の不要な重合反応の発生、画像露光時の不要なカブリ、画線の太り等を防止するためには、酸素透過性が高くなりすぎないことが好ましい。従って、２５℃、１気圧下における酸素透過性Ａが０．２≦Ａ≦２０（ｃｃ／ｍ^２・ｄａｙ）であることが好ましい。
上記ポリビニルアルコール（ＰＶＡ）等の（共）重合体の分子量は、２０００〜１０００万の範囲のものが使用でき、好ましくは２万〜３００万範囲のものが適当である。
【０１１７】
保護層の他の組成物として、グリセリン、ジプロピレングリコール等を（共）重合体に対して数質量％相当量添加して可撓性を付与することができ、また、アルキル硫酸ナトリウム、アルキルスルホン酸ナトリウム等のアニオン界面活性剤；アルキルアミノカルボン酸塩、アルキルアミノジカルボン酸塩等の両性界面活性剤；ポリオキシエチレンアルキルフェニルエーテル等の非イオン界面活性剤を（共）重合体に対して数質量％添加することができる。
保護層の膜厚は、０．１〜５μｍが適当であり、特に０．２〜２μｍが好適である。
【０１１８】
また、保護層の画像記録層との密着性、耐傷性等も平版印刷版原版の取り扱い上、極めて重要である。即ち、水溶性高分子化合物を含有するため親水性である保護層を、親油性である画像記録層上層に積層すると、接着力不足による保護層のはく離が生じやすく、はく離部分において、酸素による重合阻害に起因する膜硬化不良等の欠陥を引き起こすことがある。
【０１１９】
これに対して、画像記録層と保護層との間の接着性を改良すべく、種々の提案がなされている。例えば、特開昭４９−７０７０２号公報及び英国特許出願公開第１３０３５７８号明細書には、主にポリビニルアルコールからなる親水性ポリマー中に、アクリル系エマルション、水不溶性ビニルピロリドン−ビニルアセテート共重合体等を２０〜６０質量％混合させ、画像記録層上に積層することにより、十分な接着性が得られることが記載されている。本発明においては、これらの公知の技術をいずれも用いることができる。保護層の塗布方法については、例えば、米国特許第３，４５８，３１１号明細書及び特開昭５５−４９７２９号公報に詳細に記載されている。
更に、保護層には、他の機能を付与することもできる。例えば、露光に用いられる赤外線の透過性に優れ、かつ、それ以外の波長の光を効率よく吸収しうる、着色剤（例えば、水溶性染料）の添加により、感度低下を引き起こすことなく、セーフライト適性を向上させることができる。
【０１２０】
〔平版印刷方法〕
本発明の平版印刷方法においては、上述した本発明の平版印刷版原版を、赤外線レーザーで画像様に露光する。
本発明に用いられる赤外線レーザーは、特に限定されないが、波長７６０〜１２００ｎｍの赤外線を放射する固体レーザー及び半導体レーザーが好適に挙げられる。赤外線レーザーの出力は、１００ｍＷ以上であるのが好ましい。また、露光時間を短縮するため、マルチビームレーザーデバイスを用いるのが好ましい。
１画素あたりの露光時間は、２０μ秒以内であるのが好ましい。また、照射エネルギー量は、１０〜３００ｍＪ／ｃｍ^２ であるのが好ましい。
【０１２１】
本発明の平版印刷方法においては、上述したように、本発明の平版印刷版原版を赤外線レーザーで画像様に露光した後、なんらの現像処理工程を経ることなく油性インキと水性成分とを供給して印刷する。
具体的には、平版印刷版原版を赤外線レーザーで露光した後、現像処理工程を経ることなく印刷機に装着して印刷する方法、平版印刷版原版を印刷機に装着した後、印刷機上において赤外線レーザーで露光し、現像処理工程を経ることなく印刷する方法等が挙げられる。
【０１２２】
平版印刷版原版を赤外線レーザーで画像様に露光した後、湿式現像処理工程等の現像処理工程を経ることなく水性成分と油性インキとを供給して印刷すると、画像記録層の露光部においては、露光により硬化した画像記録層が、親油性表面を有する油性インキ受容部を形成する。一方、未露光部においては、供給された水性成分及び／又は油性インキによって、未硬化の画像記録層が溶解し又は分散して除去され、その部分に親水性の表面が露出する。
その結果、水性成分は露出した親水性の表面に付着し、油性インキは露光領域の画像記録層に着肉し、印刷が開始される。ここで、最初に版面に供給されるのは、水性成分でもよく、油性インキでもよいが、水性成分が未露光部の画像記録層により汚染されることを防止する点で、最初に油性インキを供給するのが好ましい。水性成分及び油性インキとしては、通常の平版印刷用の湿し水と印刷インキが用いられる。
このようにして、平版印刷版原版はオフセット印刷機上で機上現像され、そのまま多数枚の印刷に用いられる。
【０１２３】
【実施例】
以下、実施例によって本発明を説明するが、本発明はこれらの実施例に限定されるものではない。
【０１２４】
１．支持体の作製
Ａｌ：９９．５質量％以上、Ｆｅ：０．３０質量％、Ｓｉ：０．１０質量％、Ｔｉ：０．０２質量％、Ｃｕ：０．０１３質量％を含有し、残部は不可避不純物のＪＩＳ Ａ１０５０アルミニウム合金の溶湯に清浄化処理を施し、鋳造した。清浄化処理としては、溶湯中の水素等の不要なガスを除去するために脱ガス処理し、更に、セラミックチューブフィルタ処理を行った。鋳造法はＤＣ鋳造法で行った。凝固した板厚５００ｍｍの鋳塊の表面を１０ｍｍ面削し、金属間化合物が粗大化してしまわないように５５０℃で１０時間均質化処理を行った。ついで、４００℃で熱間圧延し、連続焼鈍炉中、５００℃で６０秒間、中間焼鈍した後、冷間圧延を行って、厚さ０．３０ｍｍのアルミニウム圧延板とした。圧延ロールの粗さを制御することにより、冷間圧延後の中心線平均粗さＲａを０．２μｍに制御した。その後、平面性を向上させるためにテンションレベラーにかけた。得られたアルミニウム板を、以下に示す表面処理に供した。
【０１２５】
まず、アルミニウム板の表面の圧延油を除去するため、１０質量％アルミン酸ソーダ水溶液を用いて５０℃で３０秒間、脱脂処理を施し、その後、３０質量％硫酸水溶液を用いて５０℃で３０秒間、中和及びスマット除去処理を施した。
ついで、画像記録層と支持体との密着性を良好にし、かつ、非画像部に保水性を与えるため、粗面化処理を施した。具体的には、間接給電セルに供給された、硝酸１質量％及び硝酸アルミニウム０．５質量％を含有する水溶液（液温４５℃）中を、アルミニウム板のウェブを通過させながら、電流密度２０Ａ／ｄｍ^２ 、ｄｕｔｙ比１：１の交番波形で、アルミニウム板が陽極時の電気量が２４０Ｃ／ｄｍ^２ となるように電解して、電気化学的粗面化処理を施した。
更に、１０質量％アルミン酸ソーダ水溶液を用いて５０℃で３０秒間、エッチング処理を施し、その後、３０質量％硫酸水溶液を用いて５０℃で３０秒間、中和及びスマット除去処理を施した。
【０１２６】
その後、耐摩耗性、耐薬品性及び保水性を向上させるために、陽極酸化処理を施した。具体的には、間接給電セルに供給された、２０質量％硫酸水溶液（液温３５℃）中を、アルミニウム板のウェブを通過させながら、電流密度１４Ａ／ｄｍ^２ の直流で電解して、２．５ｇ／ｍ^２ の陽極酸化皮膜を作製した。
その後、非画像部の親水性を確保するため、１．５質量％３号ケイ酸ソーダ水溶液を用いて７０℃で１５秒間、シリケート処理を施した。Ｓｉの付着量は１０ｍｇ／ｍ^２ であった。その後、水洗して、支持体を得た。得られた支持体の中心線平均粗さＲ_ａ は０．２５μｍであった。
【０１２７】
２．平版印刷版原版の作製
〔実施例１〜４〕
上記支持体上に、下記組成の画像記録層塗布液（１）を塗布量が０．５ｇ／ｍ^２になるように塗布した後、７０℃、６０秒でオーブン乾燥した。更にその上に画像記録層塗布液（２）を塗布量が０．５ｇ／ｍ^２になるようにワイヤーバーで塗布した後、同様に７０℃、６０秒でオーブン乾燥し、２層構成の画像記録層を有する平版印刷版原版１を得た。また、各層の塗布量を表１記載の値に変更した平版印刷版原版２〜４を作製した。
【０１２８】
画像記録層塗布液（１）
・水 １００ｇ
・下記のマイクロカプセル（１）（固形分換算で） ５ｇ
・重合開始剤（本明細書記載のＯＳ−７） ０．５ｇ
・下記のフッ素系界面活性剤（１） ０．２ｇ
【０１２９】
【化９】

【０１３０】
（マイクロカプセル（１）の合成）
油相成分として、トリメチロールプロパンとキシレンジイソシアナート付加体（三井武田ケミカル（株）製、タケネートＤ−１１０Ｎ）１０ｇ、ペンタエリスリトールトリアクリレート（日本化薬（株）製、ＳＲ４４４）３．１５ｇ、下記の赤外線吸収剤（１）０．３５ｇ、３−（Ｎ，Ｎ−ジエチルアミノ）−６−メチル−７−アニリノフルオラン（山本化成（株）製、ＯＤＢ）１ｇ、及びパイオニンＡ−４１Ｃ（竹本油脂（株）製）０．１ｇを酢酸エチル１７ｇに溶解した。水相成分としてＰＶＡ−２０５の４質量％水溶液４０ｇを調製した。油相成分及び水相成分を混合し、ホモジナイザーを用いて１２０００ｒｐｍで１０分間乳化した。得られた乳化物を、蒸留水２５ｇに添加し、室温で３０分攪拌後、４０℃で３時間攪拌した。このようにして得られたマイクロカプセル液の固形分濃度を、２０質量％になるように蒸留水を用いて希釈した。平均粒径は０．３μｍであった。
【０１３１】
【化１０】

【０１３２】
画像記録層塗布液（２）
・下記の赤外線吸収剤（２） ０．０５ｇ
・重合開始剤（本明細書記載のＯＳ−７） ０．２ｇ
・下記のバインダーポリマー（１）（平均分子量８万） ０．５ｇ
・重合性化合物 １．０ｇ
イソシアヌール酸ＥＯ変性トリアクリレート
（新中村化学工業（株）製、ＮＫエステルＭ−３１５）
・ビクトリアピュアブルーのナフタレンスルホン酸塩 ０．０２ｇ
・上記のフッ素系界面活性剤（１） ０．１ｇ
・メチルエチルケトン １８．０ｇ
【０１３３】
【化１１】

【０１３４】
【化１２】

【０１３５】
〔実施例５〜１１〕
実施例１と同じ支持体上に、下記組成の画像記録層塗布液（３）を塗布量が０．５ｇ／ｍ^２になるように塗布した後、７０℃、６０秒でオーブン乾燥した。更にその上に実施例１記載の画像記録層塗布液（２）を塗布量が０．５ｇ／ｍ^２になるようにワイヤーバーで塗布した後、同様に７０℃、６０秒でオーブン乾燥し、２層構成の画像記録層を有する平版印刷版原版５を得た。また、塗布量を表１記載の値に変更した平版印刷版原版６〜８を作製した。更に、画像記録層塗布液（３）のバインダーポリマーをポリアクリル酸から表１記載のポリマーに変更した平版印刷版原版９〜１１を作製した。
【０１３６】
画像記録層塗布液（３）
・下記の赤外線吸収剤（３） ０．０５ｇ
・重合開始剤（本明細書記載のＯＳ−７） ０．２ｇ
・ポリアクリル酸（重量平均分子量１０万） ０．５ｇ
・重合性化合物 １．０ｇ
トリメチロールプロパンＥＯ変性トリアクリレート
（新中村化学工業（株）製、ＳＲ９０３５）
・上記のフッ素系界面活性剤（１） ０．１ｇ
・水 １８ｇ
【０１３７】
【化１３】

【０１３８】
〔実施例１２〕
実施例１と同じ支持体上に、上記組成の画像記録層塗布液（３）を塗布量が０．５ｇ／ｍ^２になるように塗布した後、７０℃、６０秒でオーブン乾燥した。更にその上に画像記録層塗布液（４）を塗布量が０．５ｇ／ｍ^２になるようにワイヤーバーで塗布した後、同様に１００℃、６０秒でオーブン乾燥し、２層構成の画像記録層を有する平版印刷版原版１２を得た。
【０１３９】
画像記録層塗布液（４）
・水 １００ｇ
・上記のマイクロカプセル（１）（固形分換算で） ５ｇ
・重合開始剤（本明細書記載のＯＳ−７） ０．５ｇ
・上記のフッ素系界面活性剤（１） ０．２ｇ
・スチレンブタジエン系ラテックス（固形分換算で） ２．０ｇ
（日本ゼオン（株）製Ｎｉｐｏｌ ＬＸ４１６）
【０１４０】
〔実施例１３〕
実施例１と同じ支持体上に、上記組成の画像記録層塗布液（１）を塗布量が０．５ｇ／ｍ^２になるように塗布した後、７０℃、６０秒でオーブン乾燥した。更にその上に上記画像記録層塗布液（４）を塗布量が０．５ｇ／ｍ^２になるようにワイヤーバーで塗布した後、同様に１００℃、６０秒でオーブン乾燥し、２層構成の画像記録層を有する平版印刷版原版１３を得た。
【０１４１】
〔実施例１４〕
実施例１記載の平版印刷版原版１の上に、下記の保護層塗布液（１）を塗布量が０．５ｇ／ｍ^２になるようにワイヤーバーで塗布した後、７０℃、１００秒でオーブン乾燥、保護層を有する平版印刷版原版１４を得た。
【０１４２】
保護層塗布液（１）
・ポリビニルアルコール（ケン化度９８．５％） １．０ｇ
（（株）クラレ製、ＰＶＡ１０５）
・上記のフッ素系界面活性剤（１） ０．１ｇ
・水 １９．０ｇ
【０１４３】
〔実施例１５〕
実施例１と同じ支持体上に、下記の下塗り層塗布液（１）を塗布量が１０ｍｇ／ｍ^２になるようワイヤーバーで塗布した後、１００℃、６０秒でオーブン乾燥し、下塗り層を有する支持体を得た。この支持体を用いて、実施例１記載と同様の方法で、２層構成の画像記録層からなる平版印刷版原版１５を得た。
【０１４４】
下塗り層塗布液（１）
・下記メタクリル末端ＥＯ変性リン酸エステル化合物（１） ０．５ｇ
（ユニケミカル（株）製、ＡＭ５４０）
・メタノール ２００ｇ
【０１４５】
【化１４】

【０１４６】
〔比較例１〕
実施例１記載の画像記録層塗布液（１）を塗布量が１．０ｇ／ｍ^２になるように塗布、乾燥した下層画像記録層のみの平版印刷版原版を比較用平版印刷版原版１とした。
【０１４７】
〔比較例２〕
実施例１記載の画像記録層塗布液（２）を塗布量が１．０ｇ／ｍ^２になるように塗布、乾燥した上層画像記録層のみの平版印刷版原版を比較用平版印刷版原版２とした。
【０１４８】
〔比較例３〕
実施例５記載の画像記録層塗布液（３）を塗布量が１．０ｇ／ｍ^２になるように塗布、乾燥した下層画像記録層のみの平版印刷版原版を比較用平版印刷版原版３とした。
【０１４９】
〔比較例４〕
実施例１２記載の画像記録層塗布液（４）を塗布量が１．０ｇ／ｍ^２になるように塗布、乾燥した下層画像記録層のみの平版印刷版原版を比較用平版印刷版原版４とした。
【０１５０】
３．平版印刷版原版の評価
（機上現像性の評価）
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ー搭載のＣｒｅｏ社製Ｔｒｅｎｄｓｅｔｔｅｒ ３２４４ ＶＸにて、出力９Ｗ、外面ドラム回転数２１０ｒｐｍ、解像度２４００ｄｐｉの条件で露光した後、現像処理することなく、ハイデルベルグ社製印刷機ＳＯＲ−Ｍのシリンダーに取り付けた。ＥＵ−３（富士写真フイルム（株）製エッチ液）／水／イソプロピルアルコールが容量比１／８９／１０からなる湿し水とＴＲＡＮＳ−Ｇ（Ｎ）墨インキ（大日本インキ化学工業（株）製）とを用い、湿し水を供給した後、毎時６０００枚の印刷速度で印刷を行った。画像記録層の未露光部分の機上現像が完了し、非画像部で印刷用紙にインキが転写しない状態になるまでに要した印刷用紙の枚数を機上現像性として計測した。結果を下記表１に示した。
【０１５１】
（耐刷性の評価）
機上現像性の評価に引き続いて耐刷性の評価を行った。印刷枚数を増やしていくと徐々に画像記録層が磨耗しインキ受容性が低下するため、印刷用紙でのインキ濃度が低下する。インキ濃度が印刷開始時よりも０．１低下したときの印刷枚数を耐刷枚数として計測した。なお、インキ濃度の測定は、マクベス社製反射濃度計ＲＤ９１８を用いた。結果を下記表１に示した。
【０１５２】
【表１】

【０１５３】
表１から明らかなように、本発明の平版印刷版原版を用いた本発明の平版印刷方法によれば、従来の平版印刷版原版を用いた場合に比べて、機上現像性と耐刷性が高い水準で両立していることが分る。一方、単層構成の比較例１〜４は、明らかに機上現像性に劣り、耐刷性も不十分である。
【０１５４】
【発明の効果】
本発明によれば、機上現像性と耐刷性を高い水準で両立できる平版印刷版原版及びそれを用いた平版印刷方法を提供できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lithographic printing plate precursor and a lithographic printing method using the same. Specifically, a lithographic printing plate precursor capable of direct plate making by scanning with an infrared laser based on a digital signal of a computer or the like, and developing the lithographic printing plate precursor on a printing machine, so-called direct plate making is possible. The present invention relates to a planographic printing method for printing.
[0002]
[Prior art]
In general, a lithographic printing plate comprises an oleophilic image area that receives ink in the printing process and a hydrophilic non-image area that receives dampening water. Lithographic printing utilizes the property that water and oil-based inks repel each other, so that the oleophilic image area of the lithographic printing plate is the ink receiving area, and the hydrophilic non-image area is dampened with the water receiving area (ink non-receiving area). In this method, a difference in ink adhesion is caused on the surface of the lithographic printing plate, and after ink is applied only to the image area, the ink is transferred to a printing medium such as paper and printed.
In order to produce this lithographic printing plate, conventionally, a lithographic printing plate precursor (PS plate) in which an oleophilic photosensitive resin layer (image recording layer) is provided on a hydrophilic support has been widely used. Normally, after exposing a lithographic printing plate precursor through an original image such as a lithographic film, the image recording layer in the image area is left, and the image recording layer in the non-image area is dissolved with an alkaline developer or an organic solvent. The lithographic printing plate is obtained by carrying out plate making by a method of exposing the surface of the hydrophilic support by removing it.
[0003]
In the conventional plate-making process of a lithographic printing plate precursor, a step of dissolving and removing the non-image area with a developing solution or the like corresponding to the image recording layer is necessary after exposure. One of the problems is to make the system unnecessary or simplified. In particular, in recent years, disposal of waste liquids discharged with wet processing has become a major concern for the entire industry due to consideration for the global environment, and therefore, the demand for solving the above-mentioned problems has become stronger.
[0004]
On the other hand, as one of simple plate making methods, an image recording layer that can remove a non-image portion of a lithographic printing plate precursor in a normal printing process is used. A method called on-press development has been proposed in which a part is removed to obtain a lithographic printing plate.
As a specific method of on-press development, for example, a method of using a lithographic printing plate precursor having an image recording layer that can be dissolved or dispersed in an fountain solution, an ink solvent, or an emulsion of a fountain solution and an ink. , A method of mechanically removing the image recording layer by contact with an impression cylinder or a blanket cylinder of a printing press, a cohesive force of the image recording layer by penetration of dampening water, an ink solvent, or the like. There is a method in which after the adhesive force is weakened, the image recording layer is mechanically removed by contact with an impression cylinder or a blanket cylinder.
In the present invention, unless otherwise specified, the “development process step” refers to using a device other than a printing press (usually an automatic developing machine) and bringing a liquid (usually an alkaline developer) into contact therewith. Refers to the process of removing the unexposed portion of the image recording layer of the lithographic printing plate precursor and exposing the surface of the hydrophilic support, and “on-press development” refers to a liquid (usually printing ink) using a printing press. And / or a dampening solution) to remove the unexposed portion of the image recording layer of the lithographic printing plate precursor and expose the surface of the hydrophilic support.
[0005]
On the other hand, in recent years, digitization techniques for electronically processing, storing, and outputting image information by a computer have become widespread, and various new image output methods corresponding to such digitization techniques are put into practical use. It is becoming. Along with this, digitized image information is carried by high-convergence radiation such as laser light, and the lithographic printing plate precursor is scanned and exposed with that light, directly without using a lithographic film. Computer-to-plate (CTP) technology has been attracting attention. Accordingly, obtaining a lithographic printing plate precursor adapted to such a technique is one of the important technical issues.
[0006]
As described above, in recent years, simplification, drying, and no processing of plate making operations have become more desirable than ever in terms of consideration for the global environment and adaptation to digitalization. It is coming.
However, when the conventional image recording method using light in the ultraviolet to visible region is used for simplification of plate making operations such as on-press development, the image recording layer is not fixed even after exposure, so that it has sensitivity to room light. After the lithographic printing plate precursor was taken out of the package, it was necessary to keep it completely shielded from light until the on-press development was completed.
[0007]
Recently, high-power lasers such as semiconductor lasers that emit infrared rays having a wavelength of 760 to 1200 nm and YAG lasers have become available at low cost. The use of these high-power lasers as an image recording light source has become promising.
In a conventional plate making method using light in the ultraviolet to visible region, a photosensitive lithographic printing plate precursor is subjected to imagewise exposure from low to medium illuminance, and by image-like physical property change due to photochemical reaction in the image recording layer. Record an image. In contrast, in the method using the above-described high-power laser, a large amount of light energy is irradiated to the exposure region in an extremely short time, and the light energy is efficiently converted into heat energy. In the process, a thermal change such as a chemical change, a phase change, a form or a structure is caused, and the change is used for image recording. Therefore, image information is input by light energy such as laser light, but image recording is performed in a state in which reaction by heat energy is taken into account in addition to light energy. Usually, such a recording method using heat generated by high power density exposure is called heat mode recording, and changing light energy to heat energy is called photothermal conversion.
[0008]
The major advantages of the plate making method using heat mode recording are that the image recording layer is not exposed to light at a normal illuminance level such as indoor lighting, and that fixing of images recorded by high illuminance exposure is not essential. is there. That is, the lithographic printing plate precursor used for heat mode recording is not likely to be exposed to room light before exposure, and image fixing is not essential after exposure. Therefore, for example, if an image recording layer that is insolubilized or solubilized by exposure using a high-power laser is used, and the plate making process in which the exposed image recording layer is imaged to form a lithographic printing plate is performed by on-machine development, exposure is performed. Later, it is expected that a printing system in which an image is not affected even if exposed to ambient light in a room will be possible, and its realization is desired.
[0009]
As such a lithographic printing plate precursor, for example, a lithographic printing plate precursor in which an image forming layer in which hydrophobic thermoplastic polymer particles are dispersed in a hydrophilic binder is provided on a hydrophilic support is known ( For example, see Patent Document 1.) This lithographic printing plate precursor is exposed by an infrared laser, and the hydrophobic thermoplastic polymer particles are coalesced by heat to form an image. Then, the lithographic printing plate precursor is mounted on a cylinder of a printing machine and dampened with water and / or ink. By supplying, on-press development is possible.
However, the method for forming an image by merging the fine particles by simple thermal fusion exhibits good on-press developability, but the image strength is extremely weak and the printing durability is insufficient.
[0010]
It is also known that a lithographic printing plate precursor having an image recording layer containing microcapsules encapsulating a polymerizable compound on a hydrophilic support can be developed on-machine (see Patent Document 2 and Patent Document 3). .)
Furthermore, an on-press developable lithographic printing plate precursor having a photosensitive layer containing an infrared absorber, a radical polymerization initiator and a polymerizable compound on a support is known (see Patent Document 4).
[0011]
The method using the polymerization reaction as described above has improved the image strength because the chemical bond density of the image portion is higher than that of the image portion formed by thermal fusion of the polymer fine particles. In terms of both on-press developability and high printing durability, it is still insufficient.
[0012]
[Patent Document 1]
Japanese Patent No. 2938397
[Patent Document 2]
JP 2001-277740 A
[Patent Document 3]
JP 2001-277742 A
[Patent Document 4]
JP 2002-287334 A
[0013]
[Problems to be solved by the invention]
The present invention has been made in view of the above-described prior art, and a lithographic printing plate precursor capable of achieving both on-press developability and printing durability at a high level and a lithographic printing method using the same. It is intended to provide.
[0014]
[Means for Solving the Problems]
The inventors of the present invention provide a planographic printing plate precursor in which the image recording layer is composed of two layers consisting of a lower layer containing a hydrophilic binder polymer and an upper layer containing a hydrophobic binder polymer, and a planographic printing method using the same. The present inventors have found that the object can be achieved, and have accomplished the present invention.
That is, the present invention is as follows.
[0015]
(1) A support comprising a lower layer containing a polymerizable compound and a hydrophilic binder polymer and an upper layer containing a polymerizable compound and a hydrophobic binder polymer, and infrared absorption by at least one of the lower layer and the upper layer A lithographic printing plate precursor comprising an image recording layer which contains an agent and a polymerization initiator, can be recorded by infrared irradiation, and can be removed by printing ink and / or fountain solution.
[0016]
(2) The lithographic printing plate precursor as described in (1) above, wherein the polymerizable compound is encapsulated in microcapsules in at least one of the lower layer and the upper layer.
[0017]
(3) The support comprises a lower layer containing a polymerizable compound and a hydrophilic binder polymer, and an upper layer containing a polymerizable compound and a hydrophobic binder polymer, and infrared absorption by at least one of the lower layer and the upper layer. A lithographic printing plate precursor containing an agent and a polymerization initiator and having an image recording layer that can be recorded by infrared irradiation is mounted on a printing press and exposed imagewise with an infrared laser, or imagewise with an infrared laser. A lithographic printing method comprising: printing on a printing press, supplying printing ink and fountain solution to the lithographic printing plate precursor, removing an unexposed portion of the infrared laser of the image recording layer, and printing.
[0018]
(4) The lithographic printing method as described in (3) above, wherein the polymerizable compound is encapsulated in microcapsules in at least one of the lower layer and the upper layer.
[0019]
In the present invention, the on-press development property and the printing durability can be achieved at a high level by employing a two-layer image recording layer. Although this mechanism of action of the present invention is not clear, it is presumed as follows.
By making the image recording layer (lower layer) at the support interface hydrophilic, the solubility in fountain solution is improved, and the on-press developability of the unexposed area (non-image area) is excellent. On the other hand, the exposed area (image area) contains a polymerizable compound in the lower layer, so that it hardens to the vicinity of the support interface, improving image strength and support adhesion, printing durability, and chemical resistance. Excellent in properties. Further, by making the upper layer oleophilic, the film strength of the image recording layer can be increased, and in particular, the water resistance that becomes a problem during handling around the printing press can be effectively improved.
It is estimated that such two image recording layers can achieve both on-press developability and printing durability at a high level.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
(Image recording layer)
The image recording layer of the present invention comprises a lower layer containing a polymerizable compound and a hydrophilic binder polymer, and an upper layer containing a polymerizable compound and a hydrophobic binder polymer, and at least one of the lower layer and the upper layer absorbs infrared rays. It contains an agent and a polymerization initiator, can be recorded by infrared irradiation, and can be removed by printing ink and / or fountain solution. Hereinafter, the components of the image recording layer will be described.
[0021]
(Binder polymer)
The hydrophilic binder polymer contained in the lower layer of the image recording layer of the present invention includes hydrophilic groups that impart on-press developability with dampening water, such as hydroxyl groups, carboxyl groups, basic nitrogen-containing groups, and the like. And a polymer that imparts appropriate strength to the image recording layer.
[0022]
Specifically, polyvinyl alcohol (PVA), modified PVA such as carboxy-modified PVA, gum arabic, polyacrylamide and copolymers thereof, acrylic acid copolymer, vinyl methyl ether / maleic anhydride copolymer, vinyl acetate / Of maleic anhydride copolymer, styrene / maleic anhydride copolymer, roasted dextrin, oxygen-degraded dextrin, enzymatically-decomposed etherified dextrin, starch and its derivatives, carboxymethylcellulose, carboxyethylcellulose, methylcellulose, hydroxyethylcellulose Cellulose derivatives such as casein, gelatin, polyvinylpyrrolidone, vinyl acetate-crotonic acid copolymer, styrene-maleic acid copolymer, alginic acid and its alkali metal salts, alkaline earth metal salts or ammonium salts, Acrylic acid, poly (ethylene oxide), water-soluble urethane resins, water-soluble polyester resins, polyhydroxyethyl acrylate, polyethylene glycol, polypropylene glycol, N- vinylcarboxamide polymers.
Of these, water-soluble binder polymers are preferable. Specifically, modified PVA such as polyvinyl alcohol (PVA) and carboxy-modified PVA, gum arabic, polyacrylamide, polyacrylic acid, acrylic acid copolymer, polyvinylpyrrolidone, and alginic acid. And the use of alkali metal salts thereof.
[0023]
The hydrophobic binder polymer contained in the upper layer of the image recording layer of the present invention is water-insoluble for the purpose of improving the moderate strength of the image recording layer, the resistance to dampening water in the exposed area, and the mechanical strength. The organic polymer compound can be mentioned. For example, polyvinyl phenol, polyvinyl halogenated phenol, polyvinyl formal, polyurea, polyimide, polycarbonate, epoxy resin, phenol novolac, or condensation resin of resole phenols and aldehyde or ketone, polyvinylidene chloride, silicone resin, polyethylene, polypropylene, polyester , Polyamide, acrylic resin, vinyl chloride resin, vinylidene chloride resin, polyvinyl butyral resin, nitrocellulose, polyacrylate, polymethacrylate, polycarbonate, polyurethane, polystyrene, vinyl chloride resin-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl Alcohol copolymer, vinyl chloride-resin vinyl-maleic acid copolymer, vinyl chloride-acrylate copolymer, polyvinyl chloride Isopropylidene, vinylidene chloride - like acrylonitrile copolymer.
[0024]
As the hydrophobic binder polymer of the present invention, an aqueous emulsion of a water-insoluble organic polymer compound can also be used. The aqueous emulsion is a hydrophobic polymer suspension aqueous solution in which particles comprising fine polymer particles and, if necessary, a protective agent for dispersing and stabilizing the particles are dispersed in water.
Specific examples of aqueous emulsions used include vinyl polymer latex (polyacrylate, vinyl acetate, ethylene-vinyl acetate, etc.), conjugated cyanene polymer latex (methyl methacrylate-butadiene, styrene-butadiene, (Ronitrile-butadiene, chloroprene, etc.) and polyurethane resins.
[0025]
The hydrophilic or hydrophobic binder polymer of the present invention can have crosslinkability in order to improve the film strength of the image area. In order to impart crosslinkability to the binder polymer, a crosslinkable functional group such as an ethylenically unsaturated bond may be introduced into the main chain or side chain of the polymer. The crosslinkable functional group may be introduced by copolymerization or may be introduced by a polymer reaction.
[0026]
Examples of the polymer having an ethylenically unsaturated bond in the main chain of the molecule include poly-1,4-butadiene and poly-1,4-isoprene.
[0027]
Examples of polymers having ethylenically unsaturated bonds in the side chain of the molecule are polymers of esters or amides of acrylic acid or methacrylic acid, at least of the residue of the ester or amide (-COOR or CONHR R) Mention may be made of polymers having some ethylenically unsaturated bonds.
[0028]
Examples of residues having an ethylenically unsaturated bond (R above) include — (CH ₂ ) _n CR ¹ = CR ² R ³ ,-(CH ₂ O) _n CH ₂ CR ¹ = CR ² R ³ ,-(CH ₂ CH ₂ O) _n CH ₂ CR ¹ = CR ² R ³ ,-(CH ₂ ) _n NH-CO-O-CH ₂ CR ¹ = CR ² R ³ ,-(CH ₂ ) _n -O-CO-CR ¹ = CR ² R ³ And (CH ₂ CH ₂ O) ₂ -X where R ¹ ~ R ³ Each represents a hydrogen atom, a halogen atom or an alkyl group having 1 to 20 carbon atoms, an aryl group, an alkoxy group or an aryloxy group; ¹ And R ² Or R ³ And may combine with each other to form a ring. n represents an integer of 1 to 10. X represents a dicyclopentadienyl residue. ).
[0029]
Specific examples of the ester residue include -CH ₂ CH = CH ₂ , -CH ₂ CH ₂ O-CH ₂ CH = CH ₂ , -CH ₂ C (CH ₃ ) = CH ₂ , -CH ₂ CH = CH-C ₆ H ₅ , -CH ₂ CH ₂ OCOCH = CH-C ₆ H ₅ , -CH ₂ CH ₂ OCOC (CH ₃ ) = CH ₂ , -CH ₂ CH ₂ OCOCH = CH ₂ , -CH ₂ CH ₂ -NHCOO-CH ₂ CH = CH ₂ And CH ₂ CH ₂ OX (wherein X represents a dicyclopentadienyl residue).
Specific examples of amide residues include -CH ₂ CH = CH ₂ , -CH ₂ CH ₂ -Y (wherein Y represents a cyclohexene residue), -CH ₂ CH ₂ -OCO-CH = CH ₂ Is mentioned.
[0030]
The binder polymer having crosslinkability, for example, has a free radical (polymerization initiation radical or a growth radical in the polymerization process of the polymerizable compound) added to the crosslinkable functional group, and the polymerization chain of the polymerizable compound is formed directly between the polymers. Through addition polymerization, a cross-link is formed between the polymer molecules and cured. Alternatively, atoms in the polymer (eg, hydrogen atoms on carbon atoms adjacent to the functional bridging group) are abstracted by free radicals to form polymer radicals that are bonded together, thereby causing cross-linking between polymer molecules. Forms and cures.
[0031]
The content of the crosslinkable group in the binder polymer (content of unsaturated double bond capable of radical polymerization by iodine titration) is preferably 0.1 to 10.0 mmol, more preferably 1.0, per 1 g of the binder polymer. -7.0 mmol, most preferably 2.0-5.5 mmol.
[0032]
The hydrophilic or hydrophobic binder polymer used in the present invention preferably has a weight average molecular weight of 5,000 or more, more preferably 10,000 to 300,000, and a number average molecular weight of 1,000 or more. More preferably, it is 2000-250,000. The polydispersity (weight average molecular weight / number average molecular weight) is preferably 1.1 to 10.
[0033]
The hydrophilic or hydrophobic binder polymer of the present invention may be any of a random polymer, a block polymer, a graft polymer, etc., but is preferably a random polymer.
The binder polymer can be synthesized by a conventionally known method. The binder polymer having a crosslinkable group in the side chain can be easily synthesized by radical polymerization or polymer reaction.
[0034]
The hydrophilic or hydrophobic binder polymer of the present invention may be used alone or in combination of two or more. In order to improve on-press development, a hydrophilic binder polymer can be used in combination with the upper layer containing the hydrophobic binder polymer as long as the effect of the upper layer being hydrophobic is not impaired.
[0035]
The content of the hydrophilic or hydrophobic binder polymer of the present invention is 5 to 90% by mass, preferably 5 to 70% by mass, and preferably 5 to 50% by mass with respect to the total solid content of the lower layer or upper layer. It is more preferable that Within this range, good image area strength and image formability can be obtained.
Moreover, it is preferable to use a polymeric compound and a binder polymer in the quantity used as 1 / 9-7 / 3 by mass ratio.
[0036]
(Polymerizable compound)
The polymerizable compound used in the present invention is an addition polymerizable compound having at least one ethylenically unsaturated double bond, and is selected from compounds having at least one, preferably two or more terminal ethylenically unsaturated bonds. 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.), and 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, an addition reaction product of an unsaturated carboxylic acid ester or amide having a nucleophilic substituent such as a hydroxyl group, amino group or mercapto group with a monofunctional or polyfunctional isocyanate or epoxy, and monofunctional or polyfunctional A dehydration condensation reaction product with a functional carboxylic acid is also preferably used. Further, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an epoxy group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, a halogen group or In addition, a substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as a tosyloxy group and 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, vinyl ether or the like instead of the unsaturated carboxylic acid.
[0037]
Specific examples of the monomer of an ester of an aliphatic polyhydric alcohol compound and an unsaturated carboxylic acid include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, and tetramethylene glycol. Diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane tri (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate , Tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate , Pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tri (acryloyloxyethyl) isocyanurate, polyester acrylate oligomer.
[0038]
Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloxy- 2-hydroxypro ) Phenyl] dimethyl methane, bis - [p- (methacryloxyethoxy) phenyl] dimethyl methane.
[0039]
Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate. Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate. Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate. Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.
[0040]
Examples of other esters include aliphatic alcohol esters described in JP-B-46-27926, JP-B-51-47334, JP-A-57-196231, and JP-A-59-5240. No. 1, JP-A-59-5241, JP-A-2-226149, those having an aromatic skeleton, those having an amino group described in JP-A-1-165613, etc. are preferably used. It is done. Furthermore, the ester monomers described above can also be used as a mixture.
[0041]
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 No. 54-21726.
[0042]
Further, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable. Specific examples thereof include, for example, one molecule described in JP-B-48-41708. A vinylurethane 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 general formula (A) to a polyisocyanate compound having two or more isocyanate groups Etc.
[0043]
CH ₂ = C (R ₄ ) COOCH ₂ CH (R ₅ ) OH (A)
(However, R ₄ And R ₅ Is H or CH ₃ Indicates. )
[0044]
Also, urethane acrylates such as those described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-B-58-49860, JP-B-56- Urethane compounds having an ethylene oxide skeleton described in Japanese Patent No. 17654, Japanese Patent Publication No. 62-39417, and Japanese Patent Publication No. 62-39418 are also suitable. Furthermore, addition 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 are used. Depending on the case, it is possible to obtain a photopolymerizable composition excellent in the photosensitive speed.
[0045]
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. Mention may be made of polyfunctional acrylates and methacrylates such as reacted epoxy acrylates. In addition, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337, JP-B-1-40336, and vinylphosphonic acid-based compounds described in JP-A-2-25493 are also included. Can 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.
[0046]
About these polymerizable compounds, the details of usage such as the structure, single use or combination, addition amount and the like can be arbitrarily set according to the performance design of the final lithographic printing plate precursor. For example, it is selected from the following viewpoints.
From the viewpoint of sensitivity, a structure having a large 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 area, that is, the cured film, those having three or more functionalities are preferable, and furthermore, different functional numbers and different polymerizable groups (for example, acrylic acid ester, methacrylic acid ester, styrene compound, vinyl ether type). A method of adjusting both sensitivity and strength by using a compound) is also effective.
Further, the selection and use method of the polymerizable compound is also an important factor for the compatibility and dispersibility with other components (for example, binder polymer, initiator, colorant, etc.) in the image recording layer. In some cases, the compatibility can be improved by using a low-purity compound or by using two or more kinds in combination. In addition, a specific structure may be selected for the purpose of improving adhesion to a support or an overcoat layer described later.
[0047]
In the present invention, as a method for containing the polymerizable compound in the image recording layer, in addition to a method in which the polymerizable compound is contained in a molecular dispersion form that is dissolved in an appropriate solvent and applied, for example, JP-A-2001-2001 As described in Japanese Patent Application Laid-Open No. 277740 and Japanese Patent Application Laid-Open No. 2001-277742, a method in which a polymerizable compound is included in a microcapsule and contained in an image recording layer can also be used. Further, the method of encapsulating in microcapsules and the method of incorporating in a molecular dispersion form outside the microcapsules may be used in combination.
[0048]
The storage stability is improved by encapsulating the polymerizable compound in microcapsules and separating it from the polymerization initiator. The addition of the polymerizable compound by the microcapsule may be only the lower layer, only the upper layer, or both the lower layer and the upper layer. However, the microcapsule is water-dispersible, and the capsule particles are pointed to the support. Since it is in contact, there is little influence of thermal diffusion, so it is preferable to add to the lower layer.
[0049]
As a method for microencapsulating the polymerizable compound, a known method can be applied. For example, as a method for producing microcapsules, a method using coacervation found in US Pat. Nos. 2,800,547 and 2,800,498, each specification of US Pat. No. 3,287,154, Japanese Patent Publication No. 38-19574, 42-446 by the interfacial polymerization method, US Pat. No. 3,418,250, US Pat. No. 3,660,304 by precipitation of polymer, US Pat. No. 3,796,669, isocyanate polyol A method using a wall material, a method using an isocyanate wall material found in US Pat. No. 3,914,511, and a urea-formaldehyde system found in US Pat. Nos. 4,001,140, 4,087,376 and 4,089,802. Or urea formaldehyde-resorcinol A method using a wall forming material, a method using a wall material such as melamine-formaldehyde resin, hydroxycellulose, etc. found in US Pat. No. 4,025,445, and Japanese Patent Publication Nos. 36-9163 and 51-9079. In situ method by monomer polymerization, spray drying method found in British Patent No. 930422, US Pat. No. 3,111,407, electrolytic dispersion cooling method seen in British Patent Nos. 952807 and 967074, etc. However, it is not limited to these.
[0050]
A preferable microcapsule wall used in the present invention has a three-dimensional cross-linking and has a property of swelling with a solvent. From such a viewpoint, the wall material of the microcapsule is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and particularly preferably polyurea and polyurethane. In addition, a compound having a crosslinkable functional group such as an ethylenically unsaturated bond that can be introduced into the binder polymer may be introduced into the microcapsule wall.
[0051]
The average particle size of the microcapsules is preferably 0.01 to 3.0 μm. 0.05-2.0 micrometers is further more preferable, and 0.10-1.0 micrometer is especially preferable. Within this range, good resolution and stability over time can be obtained.
[0052]
In the present invention, the polymerizable compound is preferably used in the range of 5 to 80% by mass, more preferably 25 to 75% by mass in the lower layer and the upper layer, respectively. These may be used alone or in combination of two or more. In addition, as for the method of using the polymerizable compound, an appropriate structure, blending, and addition amount can be arbitrarily selected from the viewpoints of polymerization inhibition with respect to oxygen, resolution, fogging property, refractive index change, surface tackiness, and the like.
[0053]
(Infrared absorber)
The image recording layer of the present invention contains an infrared absorbing agent in order to efficiently perform image formation using a laser emitting infrared light of 760 to 1200 nm as a light source. The infrared absorber has a function of converting absorbed infrared rays into heat. Due to the heat generated at this time, a polymerization initiator (radical generator) described later is thermally decomposed to generate radicals. Such an infrared absorber used in the present invention is a dye or pigment having an absorption maximum at a wavelength of 760 to 1200 nm.
[0054]
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.
Preferred dyes include, for example, cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, JP-A-58-173696, The methine dyes described in JP-A-58-181690 and JP-A-58-194595, JP-A-58-112793, JP-A-58-224793, JP-A-59-48187, Naphthoquinone dyes described in JP-A-59-73996, JP-A-60-52940, JP-A-60-63744, and the like, squarylium dyes described in JP-A-58-112792, and the like; And cyanine dyes described in British Patent No. 434,875.
[0055]
In addition, a near infrared absorption sensitizer described in US Pat. No. 5,156,938 is also preferably used, and a substituted arylbenzo (thio) described in US Pat. No. 3,881,924 is also suitable. ) Pyrylium salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, 58-220143, 59- No. 41363, No. 59-84248, No. 59-84249, No. 59-146063, No. 59-146061, and Pyrlium compounds described in JP-A-59-216146. In US Pat. No. 4,283,475, the pentamethine thiopyrylium salt, etc., and Japanese Patent Publication Nos. 5-13514 and 5-19702 are disclosed. Pyrylium compounds are also preferably used. Another example of a preferable dye is a near-infrared absorbing dye described in US Pat. No. 4,756,993 as formulas (I) and (II).
Other preferable examples of the infrared absorbent of the present invention include specific indolenine cyanine dyes described in JP-A-2002-278057.
[0056]
Particularly preferred among these dyes are cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Further, cyanine dyes and indolenine cyanine dyes are preferable, and one particularly preferable example is a cyanine dye represented by the following general formula (i).
[0057]
[Chemical 1]

[0058]
In general formula (i), X ¹ Is a hydrogen atom, a halogen atom, -NPh ₂ , X ² -L ¹ Or the group shown below is represented.
[0059]
[Chemical 2]

[0060]
Where X ² Represents an oxygen atom, a nitrogen atom, or a sulfur atom, and L ¹ Represents a hydrocarbon group having 1 to 12 carbon atoms, an aromatic ring having a hetero atom, or a hydrocarbon group having 1 to 12 carbon atoms including a hetero atom. Here, the hetero atom represents N, S, O, a halogen atom, or Se. Xa ⁻ Is Za which will be described later ⁻ Is defined in the same way as R ^a Represents a substituent selected from a hydrogen atom, an alkyl group, an aryl group, a substituted or unsubstituted amino group, and a halogen atom.
[0061]
R ¹ And R ² Each independently represents a hydrocarbon group having 1 to 12 carbon atoms. From the storage stability of the recording 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.
[0062]
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. Za ⁻ Represents a counter anion. However, when the cyanine dye represented by the general formula (i) has an anionic substituent in its structure and neutralization of charge is not necessary, Za ⁻ Is not necessary. Preferred Za ⁻ Is a halogen ion, a perchlorate ion, a tetrafluoroborate ion, a hexafluorophosphate ion, and a sulfonate ion, particularly preferably a perchlorate ion or a hexafluorophosphate ion in view of the storage stability of the recording layer coating solution. And aryl sulfonate ions.
[0063]
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. Can do.
Other particularly preferable examples include specific indolenine cyanine dyes described in JP-A-2002-278057.
[0064]
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.
[0065]
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.
[0066]
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” (Shobobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 1986). Yes.
[0067]
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. Within this range, good stability of the pigment dispersion in the image recording layer coating solution and good uniformity of the image recording layer can be obtained.
[0068]
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).
[0069]
These infrared absorbers are contained in at least one of the lower layer and the upper layer of the image recording layer. It can also be contained in a microcapsule together with the polymerizable compound. As the addition amount of the infrared absorber to the image recording layer, the absorbance at the maximum absorption wavelength in the wavelength range of 760 nm to 1200 nm of the added layer seems to be in the range of 0.3 to 1.2 by the reflection measurement method. Add to. Preferably, it is the range of 0.4-1.1. Within this range, good film strength of the image area can be obtained.
Absorbance can be measured by a conventional method. As a measuring method, for example, on a reflective support such as aluminum, an image recording layer having a thickness appropriately determined in a range in which the coating amount after drying is necessary as a lithographic printing plate is formed, and the reflection density is set to the optical density. And a method of measuring with a spectrophotometer by a reflection method using an integrating sphere.
[0070]
(Polymerization initiator)
The polymerization initiator that can be used in the present invention generates radicals by heat, light, or both energies to initiate and advance the curing reaction of the polymerizable compound. As a polymerization initiator for this purpose, a thermal decomposition type radical generator that decomposes by heat to generate radicals is useful. Such a radical generator is used in combination with the above-described infrared absorber, so that when the infrared laser is irradiated, the infrared absorber generates heat, and the heat generates radicals. Is possible.
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, and a quinonediazide, and an onium salt is preferable because it has high sensitivity. Below, the onium salt which can be used suitably as a radical polymerization initiator in this invention is demonstrated. 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 salts particularly preferably used in the present invention are onium salts represented by the following general formulas (I) to (III).
[0071]
[Chemical 3]

[0072]
In formula (I), 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 Ions, carboxylate ions, and aryl sulfonate ions.
[0073]
In formula (II), 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.
[0074]
In formula (III), 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.
[0075]
Specific examples of onium salts that can be suitably used as a radical generator in the present invention include those described in JP-A Nos. 2001-133969, 2001-343742, and 2002-148790. Can be mentioned. In the present invention, onium salts represented by general formula (I) ([OI-1] to [OI-10]) and onium salts represented by general formula (II) ([ON] which can be suitably used in the present invention are shown below. -1] to [ON-5]), and specific examples of the onium salts ([OS-1] to [OS-10]) represented by the general formula (III), are not limited thereto. .
[0076]
[Formula 4]

[0077]
[Chemical formula 5]

[0078]
[Chemical 6]

[0079]
[Chemical 7]

[0080]
[Chemical 8]

[0081]
The radical generator used in the present invention preferably has a maximum absorption wavelength of 400 nm or less. More preferably, the maximum absorption wavelength is 360 nm or less, and most preferably 300 nm or less. By making the absorption wavelength in the ultraviolet region in this way, the lithographic printing plate precursor can be handled under white light.
[0082]
These polymerization initiators are contained in the layer containing the infrared absorber among the lower layer and the upper layer of the image recording layer. As content, it is preferable that it is a mass ratio larger than 5 with respect to the said infrared absorber. The mass ratio is more preferably greater than 5 and less than 10, particularly preferably greater than 5 and less than 8. Within this range, good sensitivity and printing durability can be obtained.
These polymerization initiators may be used alone or in combination of two or more. Further, these polymerization initiators can be added to another layer in addition to the layer containing no infrared absorber or the image recording layer.
[0083]
(Other additives)
In the lower layer and the upper layer of the image recording layer of the present invention, additives other than the above components, for example, surfactants, colorants, print-out agents, polymerization inhibitors, higher fatty acid derivatives, plasticizers, inorganic fine particles, low molecular hydrophilicity A functional compound or the like can be contained as necessary. Such an additive can be added to the image recording layer in a molecularly dispersed state, but can also be added in a microcapsule together with the polymerizable compound.
[0084]
<Surfactant>
In the present invention, a surfactant can be used in the lower layer and / or the upper layer of the image recording layer in order to promote on-press developability at the start of printing and to improve the coated surface state. Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, and fluorosurfactants. Surfactant may be used independently and may be used in combination of 2 or more type.
[0085]
The nonionic surfactant used for this invention is not specifically limited, A conventionally well-known thing can be used. For example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene polystyryl phenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol Fatty acid partial esters, propylene glycol mono fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, Polyoxyethylenated castor oil, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N N- bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid ester, trialkylamine oxide, polyethylene glycol, copolymers of polyethylene glycol and polypropylene glycol.
[0086]
The anionic surfactant used in the present invention is not particularly limited, and conventionally known anionic surfactants can be used. For example, fatty acid salts, abietic acid salts, hydroxyalkane sulfonates, alkane sulfonates, dialkyl sulfosuccinate esters, linear alkyl benzene sulfonates, branched alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl phenoxy poly Oxyethylene propyl sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, N-methyl-N-oleyl taurine sodium salt, N-alkyl sulfosuccinic acid monoamide disodium salt, petroleum sulfonates, sulfated beef oil, fatty acid alkyl esters Sulfates, alkyl sulfates, polyoxyethylene alkyl ether sulfates, fatty acid monoglyceride sulfates, polyoxyethylene alcohol Ruphenyl ether sulfates, polyoxyethylene styryl phenyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkyl phenyl ether phosphates, styrene / maleic anhydride Examples thereof include partial saponification products of polymers, partial saponification products of olefin / maleic anhydride copolymers, and naphthalene sulfonate formalin condensates.
[0087]
The cationic surfactant used in the present invention is not particularly limited, and conventionally known cationic surfactants can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.
The amphoteric surfactant used in the present invention is not particularly limited, and conventionally known amphoteric surfactants can be used. Examples thereof include carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric esters, and imidazolines.
[0088]
Of the above surfactants, the term “polyoxyethylene” can be read as “polyoxyalkylene” such as polyoxymethylene, polyoxypropylene, polyoxybutylene, etc. These surfactants can also be used.
[0089]
More preferable surfactants include fluorine-based surfactants containing a perfluoroalkyl group in the molecule. Examples of such fluorosurfactants include anionic types such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and perfluoroalkyl phosphates; amphoteric types such as perfluoroalkyl betaines; Cation type such as trimethylammonium salt; perfluoroalkylamine oxide, perfluoroalkylethylene oxide adduct, oligomer containing perfluoroalkyl group and hydrophilic group, oligomer containing perfluoroalkyl group and lipophilic group, perfluoroalkyl Nonionic types such as an oligomer containing a group, a hydrophilic group and a lipophilic group, and a urethane containing a perfluoroalkyl group and a lipophilic group. Moreover, the fluorine-type surfactant described in each gazette of Unexamined-Japanese-Patent No. 62-170950, 62-226143, and 60-168144 is also mentioned suitably.
[0090]
Surfactant can be used individually or in combination of 2 or more types.
The surfactant is preferably contained in the lower layer and / or the upper layer of the image recording layer in an amount of 0.001 to 10% by mass, and more preferably 0.01 to 5% by mass.
[0091]
<Colorant>
In the image recording layer of the present invention, 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) 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 dyes described in Japanese Patent No. 293247. Also, pigments such as phthalocyanine pigments, azo pigments, carbon black, titanium oxide, etc. can be suitably used.
These colorants are preferably added since it is easy to distinguish an image area from a non-image area after image formation. The addition amount is preferably 0.01 to 10% by mass in the lower layer and / or upper layer of the image recording layer.
[0092]
<Bakeout agent>
In the image recording layer of the present invention, a compound that changes color by an acid or a radical can be added to produce a printout image. As such a compound, various dyes such as diphenylmethane, triphenylmethane, thiazine, oxazine, xanthene, anthraquinone, iminoquinone, azo, and azomethine are effectively used.
[0093]
Specific examples include brilliant green, ethyl violet, methyl green, crystal violet, basic fuchsin, methyl violet 2B, quinaldine red, rose bengal, methanyl yellow, thymol sulfophthalein, xylenol blue, methyl orange, paramethyl red, Congo Fred, Benzopurpurin 4B, α-Naphthyl Red, Nile Blue 2B, Nile Blue A, Methyl Violet, Malachide Green, Parafuchsin, Victoria Pure Blue BOH [manufactured by Hodogaya Chemical Co., Ltd.], Oil Blue # 603 [Orient Chemical Kogyo Co., Ltd.], Oil Pink # 312 [Orient Chemical Co., Ltd.], Oil Red 5B [Orient Chemical Co., Ltd.], Oil Scarlet # 308 [Orient Gaku Kogyo Co., Ltd.], Oil Red OG [Orient Chemical Co., Ltd.], Oil Red RR [Orient Chemical Co., Ltd.], Oil Green # 502 [Orient Chemical Co., Ltd.], Spiron Red BEH Special [made by Hodogaya Chemical Co., Ltd.], m-cresol purple, cresol red, rhodamine B, rhodamine 6G, sulforhodamine B, auramine, 4-p-diethylaminophenyliminonaphthoquinone, 2-carboxyanilino-4-p- Diethylaminophenyliminonaphthoquinone, 2-carboxystearylamino-4-pN, N-bis (hydroxyethyl) amino-phenyliminonaphthoquinone, 1-phenyl-3-methyl-4-p-diethylaminophenylimino-5-pyrazolone, 1-β-naphthyl-4- - dyes and p of diethylamino phenyl imino-5-pyrazolone, p ', p "- hexamethyl triamnotriphenylmethane (leuco crystal violet), and a leuco dye such as Pergascript Blue SRB (manufactured by Ciba-Geigy).
[0094]
In addition to the above, a leuco dye known as a material for thermal paper or pressure-sensitive paper is also suitable. Specific examples include crystal violet lactone, malachite green lactone, benzoylleucomethylene blue, 2- (N-phenyl-N-methylamino) -6- (Np-tolyl-N-ethyl) amino-fluorane, 2-anilino. -3-methyl-6- (N-ethyl-p-toluidino) fluorane, 3,6-dimethoxyfluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) ) -Fluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, 3- (N, N-diethylamino) -6-methyl-7-anilinofluorane, 3 -(N, N-diethylamino) -6-methyl-7-xylidinofluorane, 3- (N, N-diethylamino) -6-methyl-7-chloro Fluorane, 3- (N, N-diethylamino) -6-methoxy-7-aminofluorane, 3- (N, N-diethylamino) -7- (4-chloroanilino) fluorane, 3- (N, N-diethylamino) -7-chlorofluorane, 3- (N, N-diethylamino) -7-benzylaminofluorane, 3- (N, N-diethylamino) -7,8-benzofluorane, 3- (N, N-dibutyl) Amino) -6-methyl-7-anilinofluorane, 3- (N, N-dibutylamino) -6-methyl-7-xylidinofluorane, 3-piperidino-6-methyl-7-anilinofluorane 3-pyrrolidino-6-methyl-7-anilinofluorane, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-butyl- -Methylindol-3-yl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl- 2-methylindol-3-yl) -4-zaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, and the like.
[0095]
The dye that changes color by an acid or a radical is preferably added to the lower layer and / or the upper layer of the image recording layer at a ratio of 0.01 to 10% by mass.
[0096]
<Thermal polymerization inhibitor>
In order to prevent unnecessary thermal polymerization of the polymerizable compound (C) during the production or storage of the image recording layer, a small amount of a thermal polymerization inhibitor is preferably added to the image recording layer of the present invention.
Examples of the thermal polymerization inhibitor 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 are preferred.
The thermal polymerization inhibitor is preferably contained in the lower layer and / or the upper layer of the image recording layer in an amount of about 0.01 to about 5% by mass.
[0097]
<Higher fatty acid derivatives, etc.>
In order to prevent polymerization inhibition due to oxygen, a higher fatty acid derivative such as behenic acid or behenic acid amide is added to the upper layer of the image recording layer of the present invention, and the surface of the upper layer is dried during the coating process. It may be unevenly distributed. The amount of the higher fatty acid derivative added is preferably about 0.1 to about 10% by mass relative to the total solid content of the upper layer.
[0098]
<Plasticizer>
The image recording layer of the present invention may contain a plasticizer in order to improve the on-press developability.
Examples of the plasticizer include phthalates such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diisobutyl phthalate, dioctyl phthalate, octyl capryl phthalate, dicyclohexyl phthalate, ditridecyl phthalate, butyl benzyl phthalate, diisodecyl phthalate, diallyl phthalate; Glycol esters such as glycol phthalate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate, triethylene glycol dicaprylate; Phosphate esters such as tricresyl phosphate and triphenyl phosphate Diisobutyl adipate, dioctyl adipate, dimethyl sebacate, dibutyl sebacate, dioct Ruazereto, aliphatic dibasic acid esters such as dibutyl maleate; polyglycidyl methacrylate, triethyl citrate, glycerin triacetyl ester, butyl laurate in.
The plasticizer is preferably contained in the lower layer and / or upper layer of the image recording layer at a ratio of about 30% by mass or less.
[0099]
<Inorganic fine particles>
The image recording layer of the present invention may contain inorganic fine particles in order to enhance the interfacial adhesion by surface roughening, improve the cured film strength of the image area, and improve the on-press developability of the non-image area.
As the inorganic fine particles, for example, silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate, or a mixture thereof is preferably exemplified.
The inorganic fine particles preferably have an average particle size of 5 nm to 10 μm, and more preferably 0.5 μm to 3 μm. Within the above range, it is possible to form a non-image portion having excellent hydrophilicity, which is stably dispersed in the image recording layer, sufficiently retains the film strength of the image recording layer, and hardly causes stains during printing.
The inorganic fine particles as described above can be easily obtained as a commercial product such as a colloidal silica dispersion.
The content of the inorganic fine particles is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total solid content of the lower layer and / or the upper layer.
[0100]
<Low molecular hydrophilic compound>
The image recording layer of the present invention may contain a hydrophilic low molecular weight compound for improving on-press developability. Examples of the hydrophilic low-molecular compound include water-soluble organic compounds such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol and the like, and ether or ester derivatives thereof, glycerin, Polyhydroxys such as pentaerythritol, organic amines such as triethanolamine and diethanolamine monoethanolamine and salts thereof, organic sulfonic acids such as toluenesulfonic acid and benzenesulfonic acid and salts thereof, organic phosphonic acids such as phenylphosphonic acid and the like Examples thereof include organic carboxylic acids such as salts thereof, tartaric acid, oxalic acid, citric acid, malic acid, lactic acid, gluconic acid and amino acids, and salts thereof.
[0101]
(Formation of image recording layer)
The lower layer and the upper layer of the image recording layer of the present invention are coated by preparing a coating solution by dispersing or dissolving the necessary components in a solvent. 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, the present invention is not limited to this. These solvents are used alone or in combination. The solid content concentration of the coating solution is preferably 1 to 50% by mass.
Various methods can be used as a coating method. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.
[0102]
The preferable ranges of the coating amount of the lower layer and the upper layer are 0.05 to 10 g / m, respectively. ² , More preferably 0.1 to 5 g / m ² More preferably, 0.1 to 3 g / m ² It is. The ratio of the coating amount of the lower layer / upper layer is preferably 1/100 to 100/1, more preferably 1/50 to 50/1, and still more preferably 1/10 to 1/1. From the standpoint of balance between on-press developability and printing durability, the lower layer coating amount is more preferably smaller than the upper layer coating amount.
[0103]
[Support]
The support used for the lithographic printing plate precursor according to the invention is not particularly limited as long as it is a dimensionally stable plate-like material. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), and paper or plastic films on which the above-mentioned metals are laminated or deposited. A preferable support includes a polyester film and an aluminum plate. Among these, an aluminum plate that has good dimensional stability and is relatively inexpensive is preferable.
[0104]
The aluminum plate is a pure aluminum plate, an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, or a plastic laminated on a thin film of aluminum or an aluminum alloy. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is preferably 10% by mass or less. In the present invention, a pure aluminum plate is preferable, but completely pure aluminum is difficult to manufacture in terms of refining technology, and therefore may contain a slightly different element. The composition of the aluminum plate is not specified, and a publicly known material can be used as appropriate.
[0105]
The thickness of the support is preferably from 0.1 to 0.6 mm, more preferably from 0.15 to 0.4 mm, and even more preferably from 0.2 to 0.3 mm.
[0106]
Prior to using the aluminum plate, it is preferable to perform a surface treatment such as roughening treatment or anodizing treatment. By the surface treatment, it is easy to improve hydrophilicity and secure adhesion between the image recording layer and the support. Prior to roughening the aluminum plate, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like for removing rolling oil on the surface is performed as desired.
[0107]
The surface roughening treatment of the aluminum plate is performed by various methods. For example, mechanical surface roughening treatment, electrochemical surface roughening treatment (surface roughening treatment for dissolving the surface electrochemically), chemical treatment, etc. Surface roughening treatment (roughening treatment that chemically selectively dissolves the surface).
As a method for the mechanical surface roughening treatment, 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.
Examples of the electrochemical surface roughening treatment include a method in which an alternating current or a direct current is used in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Another example is a method using a mixed acid as described in JP-A-54-63902.
[0108]
The surface-roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide, sodium hydroxide or the like, if necessary, further neutralized, and if desired, wear resistant. In order to increase the anodic oxidation treatment.
[0109]
As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.
The conditions for anodizing treatment vary depending on the electrolyte used and cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / day. dm ² The voltage is preferably 1 to 100 V and the electrolysis time is 10 seconds to 5 minutes. The amount of the anodized film formed is 1.0 to 5.0 g / m. ² Preferably, it is 1.5 to 4.0 g / m. ² It is more preferable that Within this range, good printing durability and good scratch resistance of the non-image area of the lithographic printing plate can be obtained.
[0110]
After the anodizing treatment, the surface of the aluminum plate is subjected to a hydrophilic treatment as necessary. The hydrophilization treatment is described in US Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902,734. There are such alkali metal silicate methods. In this method, the support is immersed in an aqueous solution such as sodium silicate or electrolytically treated. In addition, the treatment with potassium zirconate fluoride described in JP-B 36-22063, U.S. Pat. Nos. 3,276,868, 4,153,461 and 4,689, And a method of treating with polyvinylphosphonic acid as described in each specification of No.272.
[0111]
The support preferably has a center line average roughness of 0.10 to 1.2 μm. Within this range, good adhesion to the image recording layer, good printing durability and good stain resistance can be obtained.
The color density of the support is preferably 0.15 to 0.65 as the reflection density value. Within this range, good image formability by preventing halation during image exposure and good plate inspection after development can be obtained.
[0112]
[Back coat]
After surface-treating the support or forming an undercoat layer described later, a back coat can be provided on the back surface of the support, if necessary.
Examples of the back coat include hydrolysis and polycondensation of organic polymer compounds described in JP-A-5-45885, organometallic compounds or inorganic metal compounds described in JP-A-6-35174. A coating layer made of a metal oxide obtained in this manner is preferred. Among them, Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC ₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) ₄ It is preferable to use a silicon alkoxy compound such as the above because the raw material is inexpensive and easily available.
[0113]
(Undercoat layer)
In the planographic printing plate precursor of the invention used in the planographic printing method of the invention, an undercoat layer can be provided between the lower layer of the image recording layer and the support, if necessary. Since the undercoat layer functions as a heat insulating layer, heat generated by exposure with an infrared laser is not diffused to the support and can be used efficiently, so that there is an advantage that high sensitivity can be achieved. In addition, in the unexposed area, the image recording layer is easily peeled off from the support, so that the on-press developability is improved.
As the undercoat layer, specifically, a silane coupling agent having an ethylenic double bond reactive group capable of addition polymerization described in JP-A-10-282679, an ethylenic double bond reactive group Preferable examples include phosphorus compounds and the like.
The coating amount (solid content) of the undercoat layer is 0.1 to 100 mg / m ² 3 to 30 mg / m ² It is more preferable that
[0114]
[Protective layer]
In the planographic printing plate precursor of the present invention used in the planographic printing method of the present invention, image recording is performed as necessary in order to prevent the occurrence of scratches in the image recording layer, to block oxygen, and to prevent ablation during high-intensity laser exposure. A protective layer can be provided on the upper layer.
In the present invention, the exposure is usually performed in the air, but the protective layer is an image of low molecular weight compounds such as oxygen and basic substances present in the air that inhibit the image forming reaction caused by exposure in the image recording layer. This prevents the recording layer from being mixed, and prevents the image formation reaction from being hindered by exposure in the air. Therefore, the properties desired for the protective layer are low permeability of low-molecular compounds such as oxygen, furthermore, good transparency of light used for exposure, excellent adhesion to the image recording layer, and It is preferable that it can be easily removed in an on-press development process after exposure. Various studies have been made on the protective layer having such characteristics, and are described in detail, for example, in US Pat. No. 3,458,311 and JP-A-55-49729.
[0115]
Examples of the material used for the protective layer include water-soluble polymer compounds that are relatively excellent in crystallinity. Specific examples include water-soluble polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, acidic celluloses, gelatin, gum arabic, and polyacrylic acid. Among these, when polyvinyl alcohol (PVA) is used as a main component, the best results are obtained for basic characteristics such as oxygen barrier properties and development removability. The polyvinyl alcohol may be partially substituted with an ester, ether or acetal as long as it contains an unsubstituted vinyl alcohol unit for providing the oxygen barrier property and water solubility necessary for the protective layer, and a part of the other You may have a copolymerization component.
Specific examples of polyvinyl alcohol include those having a molecular weight of 300 to 2400 hydrolyzed by 71 to 100%. Specifically, for example, PVA-105, PVA-110, PVA-117, PVA-117H, PVA-120, PVA-124, PVA-124H, PVA-CS, PVA-CST, PVA manufactured by Kuraray Co., Ltd. -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, and L-8.
[0116]
The components of the protective layer (selection of PVA, use of additives, etc.), coating amount, etc. are appropriately selected in consideration of fogging properties, adhesion, scratch resistance, etc. in addition to oxygen barrier properties and development removability. In general, the higher the hydrolysis rate of PVA (that is, the higher the content of unsubstituted vinyl alcohol units in the protective layer), the higher the film thickness, the higher the oxygen barrier property, which is preferable in terms of sensitivity. . In order to prevent the occurrence of unnecessary polymerization reaction during production and storage, unnecessary fogging during image exposure, image line thickening, and the like, it is preferable that the oxygen permeability is not excessively high. Accordingly, the oxygen permeability A at 25 ° C. and 1 atm is 0.2 ≦ A ≦ 20 (cc / m ² (Day) is preferable.
The molecular weight of the (co) polymer such as polyvinyl alcohol (PVA) can be in the range of 2000 to 10 million, preferably in the range of 20,000 to 3 million.
[0117]
As another composition of the protective layer, glycerin, dipropylene glycol and the like can be added in an amount corresponding to several mass% with respect to the (co) polymer to provide flexibility. Anionic surfactants such as sodium acid salts; amphoteric surfactants such as alkylaminocarboxylates and alkylaminodicarboxylates; nonionic surfactants such as polyoxyethylene alkylphenyl ethers to the (co) polymer Mass% can be added.
The thickness of the protective layer is suitably from 0.1 to 5 μm, particularly preferably from 0.2 to 2 μm.
[0118]
In addition, adhesion of the protective layer to the image recording layer, scratch resistance, and the like are extremely important in handling the lithographic printing plate precursor. That is, when a protective layer that is hydrophilic because it contains a water-soluble polymer compound is laminated on the upper layer of the image recording layer that is oleophilic, the protective layer is easily peeled off due to insufficient adhesion, and polymerization by oxygen occurs in the peeled portion. It may cause defects such as poor film hardening due to inhibition.
[0119]
On the other hand, various proposals have been made to improve the adhesion between the image recording layer and the protective layer. For example, JP-A-49-70702 and British Patent Application No. 1303578 disclose an acrylic emulsion, a water-insoluble vinylpyrrolidone-vinyl acetate copolymer, etc. in a hydrophilic polymer mainly composed of polyvinyl alcohol. It is described that sufficient adhesiveness can be obtained by mixing 20 to 60% by mass and laminating on an image recording layer. Any of these known techniques can be used in the present invention. The method for applying the protective layer is described in detail, for example, in US Pat. No. 3,458,311 and JP-A-55-49729.
Furthermore, other functions can be imparted to the protective layer. For example, by adding a colorant (for example, a water-soluble dye) that is excellent in the transparency of infrared rays used for exposure and that can efficiently absorb light of other wavelengths, safe light is not caused. Suitability can be improved.
[0120]
[Lithographic printing method]
In the planographic printing method of the present invention, the above-described planographic printing plate precursor of the present invention is imagewise exposed with an infrared laser.
Although the infrared laser used for this invention is not specifically limited, The solid laser and semiconductor laser which radiate | emit infrared rays with a wavelength of 760-1200 nm are mentioned suitably. The output of the infrared laser is preferably 100 mW or more. In order to shorten the exposure time, it is preferable to use a multi-beam laser device.
The exposure time per pixel is preferably within 20 μsec. The irradiation energy amount is 10 to 300 mJ / cm. ² Is preferred.
[0121]
In the lithographic printing method of the present invention, as described above, after exposing the lithographic printing plate precursor of the present invention imagewise with an infrared laser, an oil-based ink and an aqueous component are supplied without any development processing steps. Print.
Specifically, after exposing the lithographic printing plate precursor with an infrared laser, it is mounted on a printing machine without passing through a development process, and after printing the lithographic printing plate precursor on the printing machine, Examples include a method of printing with an infrared laser and printing without going through a development process.
[0122]
After exposing the lithographic printing plate precursor imagewise with an infrared laser and supplying it with an aqueous component and oil-based ink without passing through a development process such as a wet development process, in the exposed part of the image recording layer, The image recording layer cured by exposure forms an oil-based ink receiving portion having an oleophilic surface. On the other hand, in the unexposed portion, the uncured image recording layer is dissolved or dispersed and removed by the supplied aqueous component and / or oil-based ink, and a hydrophilic surface is exposed in the portion.
As a result, the aqueous component adheres to the exposed hydrophilic surface, and the oil-based ink is deposited on the image recording layer in the exposed area, and printing is started. Here, the water-based component or oil-based ink may be first supplied to the plate surface, but the oil-based ink is first used in order to prevent the water-based component from being contaminated by the image recording layer in the unexposed area. It is preferable to supply. As the aqueous component and the oil-based ink, a dampening water for normal lithographic printing and a printing ink are used.
In this way, the lithographic printing plate precursor is subjected to on-press development on an offset printing machine and used as it is for printing a large number of sheets.
[0123]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.
[0124]
1. Fabrication of support
Al: 99.5% by mass or more, Fe: 0.30% by mass, Si: 0.10% by mass, Ti: 0.02% by mass, Cu: 0.013% by mass, the balance being JIS of inevitable impurities The molten A1050 aluminum alloy was subjected to a cleaning treatment and cast. As the cleaning treatment, degassing treatment was performed to remove unnecessary gas such as hydrogen in the molten metal, and further ceramic tube filter treatment was performed. The casting method was a DC casting method. The surface of the ingot having a thickness of 500 mm was chamfered by 10 mm, and homogenized at 550 ° C. for 10 hours so that the intermetallic compound would not become coarse. Subsequently, it was hot-rolled at 400 ° C., subjected to intermediate annealing at 500 ° C. for 60 seconds in a continuous annealing furnace, and then cold-rolled to obtain an aluminum rolled plate having a thickness of 0.30 mm. By controlling the roughness of the rolling roll, the centerline average roughness Ra after cold rolling was controlled to 0.2 μm. Then, it applied to the tension leveler in order to improve planarity. The obtained aluminum plate was subjected to the following surface treatment.
[0125]
First, in order to remove the rolling oil on the surface of the aluminum plate, a degreasing treatment is performed at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution, and then, at 30 ° C. for 30 seconds using a 30 mass% sulfuric acid aqueous solution. Then, neutralization and smut removal treatment were performed.
Next, a surface roughening treatment was performed in order to improve the adhesion between the image recording layer and the support and to provide water retention to the non-image area. Specifically, a current density of 20 A is passed through an aluminum plate web through an aqueous solution (liquid temperature: 45 ° C.) containing 1% by mass of nitric acid and 0.5% by mass of aluminum nitrate supplied to the indirect power supply cell. / Dm ² In the alternating waveform with a duty ratio of 1: 1, the amount of electricity when the aluminum plate is anode is 240 C / dm ² Electrolytic roughening treatment was performed by electrolysis so that
Furthermore, an etching treatment was performed at 50 ° C. for 30 seconds using a 10 mass% sodium aluminate aqueous solution, and then neutralization and smut removal treatment were performed at 50 ° C. for 30 seconds using a 30 mass% sulfuric acid aqueous solution.
[0126]
Then, in order to improve abrasion resistance, chemical resistance, and water retention, an anodizing treatment was performed. Specifically, a current density of 14 A / dm is passed through a 20% by mass sulfuric acid aqueous solution (liquid temperature: 35 ° C.) supplied to the indirect power supply cell through an aluminum plate web. ² Of 2.5 g / m ² An anodized film was prepared.
Then, in order to ensure the hydrophilic property of a non-image part, the silicate process was performed for 15 second at 70 degreeC using the 1.5 mass% No. 3 sodium silicate aqueous solution. The amount of Si deposited is 10 mg / m ² Met. Then, it washed with water and the support body was obtained. Centerline average roughness R of the obtained support _a Was 0.25 μm.
[0127]
2. Preparation of lithographic printing plate precursor
[Examples 1 to 4]
On the support, an image recording layer coating liquid (1) having the following composition was applied in an amount of 0.5 g / m. ² And then oven dried at 70 ° C. for 60 seconds. Furthermore, the coating amount of the image recording layer coating liquid (2) is 0.5 g / m. ² After coating with a wire bar, the plate was similarly dried in an oven at 70 ° C. for 60 seconds to obtain a lithographic printing plate precursor 1 having a two-layer image recording layer. In addition, lithographic printing plate precursors 2 to 4 in which the coating amount of each layer was changed to the values shown in Table 1 were prepared.
[0128]
Image recording layer coating solution (1)
・ Water 100g
・ The following microcapsule (1) (in terms of solid content) 5 g
-Polymerization initiator (OS-7 described in this specification) 0.5 g
・ 0.2 g of the following fluorosurfactant (1)
[0129]
[Chemical 9]

[0130]
(Synthesis of microcapsule (1))
As oil phase components, trimethylolpropane and xylene diisocyanate adduct (Mitsui Takeda Chemical Co., Ltd., Takenate D-110N) 10 g, pentaerythritol triacrylate (Nippon Kayaku Co., Ltd., SR444) 3.15 g, 0.35 g of the following infrared absorber (1), 3- (N, N-diethylamino) -6-methyl-7-anilinofluorane (manufactured by Yamamoto Kasei Co., Ltd., ODB) 1 g, and pionine A-41C ( 0.1 g of Takemoto Yushi Co., Ltd.) was dissolved in 17 g of ethyl acetate. As an aqueous phase component, 40 g of a 4% by mass aqueous solution of PVA-205 was prepared. The oil phase component and the aqueous phase component were mixed and emulsified for 10 minutes at 12000 rpm using a homogenizer. The obtained emulsion was added to 25 g of distilled water, stirred at room temperature for 30 minutes, and then stirred at 40 ° C. for 3 hours. The microcapsule solution thus obtained was diluted with distilled water so that the solid content concentration became 20% by mass. The average particle size was 0.3 μm.
[0131]
Embedded image

[0132]
Image recording layer coating solution (2)
・ The following infrared absorber (2) 0.05 g
-Polymerization initiator (OS-7 described in this specification) 0.2 g
・ The following binder polymer (1) (average molecular weight 80,000) 0.5 g
・ Polymerizable compound 1.0g
Isocyanuric acid EO-modified triacrylate
(Shin Nakamura Chemical Co., Ltd., NK Ester M-315)
・ Victoria Pure Blue Naphthalenesulfonate 0.02g
・ 0.1 g of the above-mentioned fluorosurfactant (1)
・ Methyl ethyl ketone 18.0g
[0133]
Embedded image

[0134]
Embedded image

[0135]
[Examples 5 to 11]
On the same support as in Example 1, the coating amount of the image recording layer coating liquid (3) having the following composition was 0.5 g / m. ² And then oven dried at 70 ° C. for 60 seconds. Furthermore, the coating amount of the image recording layer coating liquid (2) described in Example 1 is 0.5 g / m. ² After coating with a wire bar, the plate was similarly dried in an oven at 70 ° C. for 60 seconds to obtain a planographic printing plate precursor 5 having a two-layer image recording layer. In addition, lithographic printing plate precursors 6 to 8 having the coating amount changed to the values shown in Table 1 were prepared. Furthermore, lithographic printing plate precursors 9 to 11 in which the binder polymer of the image recording layer coating solution (3) was changed from polyacrylic acid to the polymers shown in Table 1 were prepared.
[0136]
Image recording layer coating solution (3)
・ The following infrared absorber (3) 0.05 g
-Polymerization initiator (OS-7 described in this specification) 0.2 g
・ Polyacrylic acid (weight average molecular weight 100,000) 0.5g
・ Polymerizable compound 1.0g
Trimethylolpropane EO modified triacrylate
(Shinnakamura Chemical Co., Ltd., SR9035)
・ 0.1 g of the above-mentioned fluorosurfactant (1)
・ Water 18g
[0137]
Embedded image

[0138]
Example 12
On the same support as in Example 1, the coating amount of the image recording layer coating liquid (3) having the above composition was 0.5 g / m. ² And then oven dried at 70 ° C. for 60 seconds. Furthermore, the coating amount of the image recording layer coating liquid (4) is 0.5 g / m. ² After being coated with a wire bar, the plate was similarly dried in an oven at 100 ° C. for 60 seconds to obtain a planographic printing plate precursor 12 having a two-layer image recording layer.
[0139]
Image recording layer coating solution (4)
・ Water 100g
-5 g of the above microcapsules (1) (in terms of solid content)
-Polymerization initiator (OS-7 described in this specification) 0.5 g
・ 0.2 g of the above-mentioned fluorosurfactant (1)
・ Styrene butadiene latex (in terms of solid content) 2.0g
(Nipol LX416 manufactured by Nippon Zeon Co., Ltd.)
[0140]
Example 13
On the same support as in Example 1, the coating amount of the image recording layer coating liquid (1) having the above composition was 0.5 g / m. ² And then oven dried at 70 ° C. for 60 seconds. Further, the coating amount of the image recording layer coating liquid (4) is 0.5 g / m. ² After coating with a wire bar, the plate was similarly dried in an oven at 100 ° C. for 60 seconds to obtain a planographic printing plate precursor 13 having an image recording layer having a two-layer structure.
[0141]
Example 14
On the planographic printing plate precursor 1 described in Example 1, the coating amount of the following protective layer coating solution (1) was 0.5 g / m. ² After that, a lithographic printing plate precursor 14 having a protective layer was obtained by oven drying at 70 ° C. for 100 seconds.
[0142]
Protective layer coating solution (1)
・ Polyvinyl alcohol (saponification degree: 98.5%) 1.0 g
(Pura 105 manufactured by Kuraray Co., Ltd.)
・ 0.1 g of the above-mentioned fluorosurfactant (1)
・ Water 19.0g
[0143]
Example 15
On the same support as in Example 1, the coating amount of the following undercoat layer coating solution (1) was 10 mg / m. ² After coating with a wire bar, it was oven dried at 100 ° C. for 60 seconds to obtain a support having an undercoat layer. Using this support, a lithographic printing plate precursor 15 comprising a two-layer image recording layer was obtained in the same manner as described in Example 1.
[0144]
Undercoat layer coating solution (1)
-0.5 g of the following methacrylic terminal EO-modified phosphate ester compound (1)
(Unichemical Corporation, AM540)
・ Methanol 200g
[0145]
Embedded image

[0146]
[Comparative Example 1]
The coating amount of the image recording layer coating liquid (1) described in Example 1 was 1.0 g / m. ² The lithographic printing plate precursor having only the lower image recording layer coated and dried as described above was designated as a comparative lithographic printing plate precursor 1.
[0147]
[Comparative Example 2]
The coating amount of the image recording layer coating liquid (2) described in Example 1 was 1.0 g / m. ² The lithographic printing plate precursor having only the upper image recording layer coated and dried as described above was used as a comparative lithographic printing plate precursor 2.
[0148]
[Comparative Example 3]
The coating amount of the image recording layer coating liquid (3) described in Example 5 was 1.0 g / m. ² The lithographic printing plate precursor having only the lower image recording layer coated and dried as described above was designated as a comparative lithographic printing plate precursor 3.
[0149]
[Comparative Example 4]
The coating amount of the image recording layer coating solution (4) described in Example 12 was 1.0 g / m. ² The lithographic printing plate precursor having only the lower image recording layer coated and dried as described above was used as a comparative lithographic printing plate precursor 4.
[0150]
3. Evaluation of planographic printing plate precursors
(Evaluation of on-press developability)
The resulting lithographic printing plate precursor was exposed to a Trend setter 3244 VX manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser under the conditions of an output of 9 W, an outer drum rotating speed of 210 rpm, and a resolution of 2400 dpi, and then developed without any processing. It was attached to a cylinder of a printer SOR-M manufactured by the company. EU-3 (Fuji Photo Film Co., Ltd. etchant) / Water / Isopropyl alcohol with a volume ratio of 1/89/10 and TRANS-G (N) black ink (Dainippon Ink Chemical Co., Ltd.) After supplying dampening water, printing was performed at a printing speed of 6000 sheets per hour. On-machine development was measured as the number of print sheets required until the on-image development of the unexposed portion of the image recording layer was completed and the ink was not transferred to the print sheet in the non-image area. The results are shown in Table 1 below.
[0151]
(Evaluation of printing durability)
Subsequent to the evaluation of on-press developability, the printing durability was evaluated. As the number of printed sheets increases, the image recording layer gradually wears and the ink acceptability decreases, so the ink density on the printing paper decreases. The number of printed sheets when the ink density was reduced by 0.1 from the start of printing was measured as the number of printed sheets. The ink density was measured using a reflection densitometer RD918 manufactured by Macbeth. The results are shown in Table 1 below.
[0152]
[Table 1]

[0153]
As is apparent from Table 1, according to the planographic printing method of the present invention using the planographic printing plate precursor of the present invention, on-press developability and printing durability compared to the case of using a conventional planographic printing plate precursor. Can be found at a high level. On the other hand, Comparative Examples 1 to 4 having a single layer structure are clearly inferior in on-press developability and insufficient in printing durability.
[0154]
【The invention's effect】
According to the present invention, it is possible to provide a lithographic printing plate precursor capable of achieving both on-press developability and printing durability at a high level and a lithographic printing method using the same.

Claims (4)

The support comprises a lower layer containing a polymerizable compound and a hydrophilic binder polymer, and an upper layer containing a polymerizable compound and a hydrophobic binder polymer. An infrared absorber and a polymer are formed on at least one of the lower and upper layers. A lithographic printing plate precursor comprising an image recording layer containing an initiator, recordable by irradiation with infrared rays, and removable by printing ink and / or dampening water. The lithographic printing plate precursor as claimed in claim 1, wherein the polymerizable compound is encapsulated in microcapsules in at least one of the lower layer and the upper layer. The support comprises a lower layer containing a polymerizable compound and a hydrophilic binder polymer, and an upper layer containing a polymerizable compound and a hydrophobic binder polymer. An infrared absorber and a polymer are formed on at least one of the lower and upper layers. A lithographic printing plate precursor containing an initiator and having an image recording layer that can be recorded by infrared irradiation is mounted on a printing press and imagewise exposed with an infrared laser, or imagewise exposed with an infrared laser. Then, a lithographic printing method for mounting in a printing machine, supplying printing ink and fountain solution to the lithographic printing plate precursor, removing an unexposed portion of the image recording layer from an infrared laser, and printing. The lithographic printing method according to claim 3, wherein the polymerizable compound is encapsulated in microcapsules in at least one of the lower layer and the upper layer.