JP2004013093A - Original plate for lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an original plate for a positive type lithographic printing plate in which high solvent resistance and high developing latitude are obtained and flaw resistance and storage stability capable of preventing printing resistance and handling from being reduced even under environments such as high temperature and high humidity are improved. <P>SOLUTION: The original plate for the positive type lithographic printing plate is constituted by successively forming a substance for absorbing light and generating light, an image recording layer containing an alkaline solution-soluble compound having phenol hydroxyl group and organic particles having alkaline solution solubility or alkaline solution dispersion and a glass transition point of ≥200°C or an overcoat layer containing inorganic particles having alkaline solution solubility or alkaline solution dispersion. <P>COPYRIGHT: (C)2004,JPO

Description

【００５８】
【化２】

【００５９】
顔料又は染料は、オーバーコート層全固形分中の１〜７０重量％、好ましくは２〜５０重量％、染料の場合、特に好ましくは２〜３０重量％、顔料の場合、特に好ましくは２０〜５０重量％の割合である。顔料又は染料の添加量が上記好ましい範囲において、好適な記録感度とオーバーコート層の均一性や耐久性が確保できる。
【００６０】
［界面活性剤］
本発明におけるオーバーコート層には、印刷条件に対する安定性を拡げるため、界面活性剤を添加することが好ましい。界面活性剤としては、ノニオン系及びアニオン系界面活性剤のほか、特開平２−１９５３５６号公報に記載されているようなカチオン界面活性剤、含フッ素界面活性剤、及び特開昭５９−１２１０４４号及び特開平４−１３１４９号公報に記載されている両性界面活性剤を添加することができる。
【００６１】
オーバーコート層に添加される好ましいノニオン界面活性剤の具体例としては、ポリオキシエチレンラウリルエーテル、ポリオキシエチレンステアリルエーテル、ポリオキシエチレンセチルエーテル、ポリオキシエチレンオレイルエーテルなどの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ノニルフェニルエーテルなどのポリオキシエチレンアルキルアリールエーテル類、ポリオキシエチレン・ポリオキシプロピレンブロックコポリマー類、更にポリオキシエチレン・ポリオキシプロピレンブロックコポリマーの端末のヒドロキシル基に炭素数５〜２４の脂肪族基がエーテル結合した複合ポリオキシアルキレンアルキルエーテル類、同じくアルキル置換アリール基がエーテル結合した複合ポリオキシアルキレンアルキルアリールエーテル類、ソルビタンモノラウレート、ソルビタンモノステアレート、ソルビタントリステアレート、ソルビタンモノパルミテート、ソルビタンモノオレート、ソルビタントリオレートなどのソルビタン脂肪酸エステル類、ポリオキシエチレンソルビタンモノラウレート、ポリオキシエチレンソルビタンモノパルミテート、ポリオキシエチレンソルビタンモノステアレート、ポリオキシエチレンソルビタントリステアレート、ポリオキシエチレンソルビタントリオレートなどのポリオキシエチレンソルビタン脂肪酸エステル類などが挙げられる。
【００６２】
両性界面活性剤の具体例としては、アルキルジ（アミノエチル）グリシン、アルキルポリアミノエチルグリシン塩酸塩、２−アルキル−Ｎ−カルボキシエチル−Ｎ−ヒドロキシエチルイミダゾリニウムベタインやＮ−テトラデシル−Ｎ，Ｎ−ベタイン型（例えば、商品名アモーゲンＫ、第一工業（株）製）等が挙げられる。
【００６３】
アニオン系活性剤の具体例としては、アルキルスルホン酸類、アリールスルホン酸類、脂肪族カルボン酸類、アルキルナフタレンスルホン酸類、アルキルナフタレンスルホン酸又はナフタレンスルホン酸とホルムアルデヒドの縮合型のもの、炭素数９〜２６の脂肪族スルホン酸類、アルキルベンゼンスルホン酸類、ラウリルポリオキシエチレン硫酸、セチルポリオキシエチレンスルホン酸、オレイルポリオキシエチレンホスホン酸などのポリオキシエチレン含有硫酸やポリオキシエチレン含有燐酸などが挙げられる。
【００６４】
カチオン活性剤の具体例としては、ラウリルアミンアセテート、ラウリルトリメチルアンモニウムクロライド、ジステアリルジメチルアンモニウムクロライド、アルキルベンジルジメチルアンモニウムクロライドなどが挙げられる。
【００６５】
オーバーコート層には、場合により更に、後述する界面活性剤の好ましい添加量の範囲内でフッ素系の界面活性剤を用いることもできる。具体的には、パーフルオロアルキル基を有する界面活性剤が好ましく、カルボン酸、スルホン酸、硫酸エステル及びリン酸エステルのいづれかを有するアニオン型のフッ素系界面活性剤、又は、脂肪族アミン、第４級アンモニウム塩のようなカチオン型のフッ素系界面活性剤、又はベタイン型のフッ素系両性界面活性剤、又は、ポリオキシ化合物の脂肪族エステル、ポリアルキレンオキシド縮合型、ポリエチレンイミン縮合型のようなフッ素系ノニオン型界面活性剤などが挙げられる。
上記界面活性剤の画像形成層全固形物中に占める割合は、０．０１〜１５質量％が好ましく、より好ましくは０．０５〜５質量％である。
【００６６】
本発明の平版印刷版原版におけるオ−バ−コ−ト層の厚みは、０．０１μｍから４．０μｍが好ましく、更にこの好ましくは、０．０５μｍから２．０μｍである。層が厚すぎると感度低下を引き起こしたり、溶解除去され現像液中に含まれるオーバーコート層成分に起因する現像液の性能劣化を促進する懸念があり、薄すぎると皮膜性が損なわれ、本発明の好ましい効果が得難い場合がある。
【００６７】
＜画像記録層＞
本発明における画像記録層としては、上記したように、光を吸収し熱を発生する物質と、フェノール性水酸基を有するアルカリ水溶液可溶性樹脂と、を含有する。
［フェノール性水酸基を有するアルカリ水溶液可溶性樹脂］
本発明で使用するフェノール性水酸基を有するアルカリ水溶液可溶性樹脂（以下、「フェノール性水酸基を有する樹脂」という。）としては、例えば、フェノールホルムアルデヒド樹脂、ｍ−クレゾールホルムアルデヒド樹脂、ｐ−クレゾールホルムアルデヒド樹脂、ｍ−／ｐ−混合クレゾールホルムアルデヒド樹脂、フェノール／クレゾール（ｍ−，ｐ−，又はｍ−／ｐ−混合のいずれでもよい）混合ホルムアルデヒド樹脂などのノボラック樹脂を挙げることができる。
【００６８】
これらのフェノール性水酸基を有する樹脂は、重量平均分子量が５００〜２００００で数平均分子量が２００〜１００００のものが好ましい。更に、米国特許第４１２３２７９号明細書に記載されているように、ｔ−ブチルフェノールホルムアルデヒド樹脂、オクチルフェノールホルムアルデヒド樹脂のような、炭素数３〜８のアルキル基を置換基として有するフェノールとホルムアルデヒドとの縮合物を併用してもよい。かかるフェノール性水酸基を有する樹脂は、１種類あるいは２種類以上を組み合わせて使用してもよい。
【００６９】
本発明では、前記フェノール性水酸基を有する樹脂と、下記（ａ）から（ｃ）のうち少なくとも一つを共重合成分として１０モル％以上含む共重合体（以下、「特定の共重合体」という。）とを併用するのが好ましい。
【００７０】
（ａ）１分子中に、窒素原子上に少なくとも一つの水素原子が結合したスルホンアミド基を有するモノマー
（ｂ）１分子中に、下記の式で表される活性イミノ基を有するモノマー
【００７１】
【化３】

【００７２】
（ｃ）それぞれフェノール性水酸基を有するアクリルアミド、メタクリルアミド、アクリル酸エステル、メタクリル酸エステル、又はヒドロキシスチレン
【００７３】
本発明における特定の共重合体は、前記（ａ）から（ｃ）のうち少なくとも一つを共重合成分として１０モル％以上含んでいることが必要とされ、２０モル％以上含むものがより好ましい。１０モル％より少ないと、フェノール性水酸基を有する樹脂との相互作用が不十分となり現像ラチチュードが低下する。また、前記（ａ）から（ｃ）以外の他の共重合成分を含んでいてもよい。
【００７４】
（ａ）に該当するモノマーとは、１分子中に、窒素原子上に少なくとも一つの水素原子が結合したスルホンアミド基と、重合可能な不飽和結合をそれぞれ一つ以上有する低分子化合物からなるモノマーである。その中でも、アクリロイル基、アリル基、又はビニロキシ基と、置換あるいはモノ置換アミノスルホニル基又は置換スルホニルイミノ基とを有する低分子化合物が好ましい。
このような化合物としては、例えば、下記一般式（Ｉ）〜（Ｖ）で示される化合物が挙げられる。
【００７５】
【化４】

【００７６】
式中、Ｘ^１、Ｘ^２はそれぞれ−Ｏ−又は−ＮＲ^１０−を示す。Ｒ^４、Ｒ^７はそれぞれ水素原子又は−ＣＨ_３を表す。Ｒ^５、Ｒ^８、Ｒ^１２、Ｒ^１５、Ｒ^１９はそれぞれ置換基を有していてもよい炭素数１〜１２のアルキレン基、シクロアルキレン基、アリーレン基又はアラルキレン基を表す。Ｒ^６、Ｒ^１０、Ｒ^１６は水素原子、それぞれ置換基を有していてもよい炭素数１〜１２のアルキル基、シクロアルキル基、アリール基又はアラルキル基を示す。また、Ｒ^９、Ｒ^２０は、それぞれ置換基を有していてもよい炭素数１〜１２のアルキル基、シクロアルキル基、アリール基、アラルキル基を示す。Ｒ^１１、Ｒ^１３、Ｒ^１７は水素原子又は−ＣＨ_３を表す。Ｒ^１４、Ｒ^１８はそれぞれ単結合又は置換基を有していてもよい炭素数１〜１２のアルキレン基、シクロアルキレン基、アリーレン基又はアラルキレン基を表す。Ｙ^１、Ｙ^２はそれぞれ単結合又は−ＣＯ−を表す。
【００７７】
具体的には、ｍ−アミノスルホニルフェニルメタクリレート、Ｎ−（ｐ−アミノスルホニルフェニル）メタクリルアミド、Ｎ−（ｐ−アミノスルホニルフェニル）アクリルアミド等を好適に使用することができる。
【００７８】
（ｂ）に該当するモノマーとは、１分子中に、前記式で表される活性イミノ基と、重合可能な不飽和結合をそれぞれ一つ以上有する低分子化合物からなるモノマーである。このような化合物としては、具体的には、Ｎ−（ｐ−トルエンスルホニル）メタクリルイミド、Ｎ−（ｐ−トルエンスルホニル）アクリルイミド等を好適に使用することができる。
【００７９】
（ｃ）に該当するモノマーとは、それぞれフェノール性水酸基を有するアクリルアミド、メタクリルアミド、アクリル酸エステル、メタクリル酸エステル、又はヒドロキシスチレンからなるモノマーである。このような化合物としては、具体的には、Ｎ−（４−ヒドロキシフェニル）アクリルアミド、Ｎ−（４−ヒドロキシフェニル）メタクリルアミド、ｏ−ヒドロキシフェニルアクリレート、ｍ−ヒドロキシフェニルアクリレート、ｐ−ヒドロキシフェニルアクリレート、ｏ−ヒドロキシフェニルメタクリレート、ｍ−ヒドロキシフェニルメタクリレート、ｐ−ヒドロキシフェニルメタクリレート、ｏ−ヒドロキシスチレン、ｍ−ヒドロキシスチレン、ｐ−ヒドロキシスチレン等を好適に使用することができる。
【００８０】
他の共重合成分としては、例えば、下記（１）〜（１２）に挙げるモノマーを用いることができる。
（１）２−ヒドロキシエチルアクリレート又は２−ヒドロキシエチルメタクリレート等の脂肪族水酸基を有するアクリル酸エステル類、及びメタクリル酸エステル類。
（２）アクリル酸メチル、アクリル酸エチル、アクリル酸プロピル、アクリル酸ブチル、アクリル酸アミル、アクリル酸ヘキシル、アクリル酸オクチル、アクリル酸ベンジル、アクリル酸−２−クロロエチル、グリシジルアクリレート、Ｎ−ジメチルアミノエチルアクリレート等のアルキルアクリレート。
（３）メタクリル酸メチル、メタクリル酸エチル、メタクリル酸プロピル、メタクリル酸ブチル、メタクリル酸アミル、メタクリル酸ヘキシル、メタクリル酸シクロヘキシル、メタクリル酸ベンジル、メタクリル酸−２−クロロエチル、グリシジルメタクリレート、Ｎ−ジメチルアミノエチルメタクリレート等のアルキルメタクリレート。
（４）アクリルアミド、メタクリルアミド、Ｎ−メチロールアクリルアミド、Ｎ−エチルアクリルアミド、Ｎ−ヘキシルメタクリルアミド、Ｎ−シクロヘキシルアクリルアミド、Ｎ−ヒドロキシエチルアクリルアミド、Ｎ−フェニルアクリルアミド、Ｎ−ニトロフェニルアクリルアミド、Ｎ−エチル−Ｎ−フェニルアクリルアミド等のアクリルアミドもしくはメタクリルアミド。
（５）エチルビニルエーテル、２−クロロエチルビニルエーテル、ヒドロキシエチルビニルエーテル、プロピルビニルエーテル、ブチルビニルエーテル、オクチルビニルエーテル、フェニルビニルエーテル等のビニルエーテル類。
【００８１】
（６）ビニルアセテート、ビニルクロロアセテート、ビニルブチレート、安息香酸ビニル等のビニルエステル類。
（７）スチレン、α−メチルスチレン、メチルスチレン、クロロメチルスチレン等のスチレン類。
（８）メチルビニルケトン、エチルビニルケトン、プロピルビニルケトン、フェニルビニルケトン等のビニルケトン類。
（９）エチレン、プロピレン、イソブチレン、ブタジエン、イソプレン等のオレフィン類。
（１０）Ｎ−ビニルピロリドン、Ｎ−ビニルカルバゾール、４−ビニルピリジン、アクリロニトリル、メタクリロニトリル等。
（１１）マレイミド、Ｎ−アクリロイルアクリルアミド、Ｎ−アセチルメタクリルアミド、Ｎ−プロピオニルメタクリルアミド、Ｎ−（ｐ−クロロベンゾイル）メタクリルアミド等の不飽和イミド。
（１２）アクリル酸、メタクリル酸、無水マレイン酸、イタコン酸等の不飽和カルボン酸。
【００８２】
本発明における特定の共重合体は、重量平均分子量が２０００以上、数平均分子量が１０００以上のものが好ましく用いられる。更に好ましくは、重量平均分子量が５０００〜３０００００、数平均分子量が２０００〜２５００００であり、分散度（重量平均分子量／数平均分子量）が１．１〜１０のものである。
かかる特定の共重合体は、１種類あるいは２種類以上を組み合わせて使用してもよい。
【００８３】
前記フェノール性水酸基を有する樹脂と前記特定の共重合体との配合重量比は５０：５０から５：９５の範囲にあることが好ましく、４０：６０から１０：９０の範囲にあることがより好ましい。これより前記フェノール性水酸基を有する樹脂の配合量が多くなると、海島構造が逆転し、耐溶剤性等を改善することが困難となる。逆に、これより前記共重合体の配合量が多くなると、前記フェノール性水酸基を有する樹脂による表面層が薄くなり過ぎ、現像ラチチュードの向上が不十分となる。
【００８４】
これらフェノール性水酸基を有する樹脂と特定の共重合体とからなるアルカリ可溶性の高分子化合物は、それぞれ１種類あるいは２種類以上を組み合わせて使用してもよく、全印刷版材料固形分中、３０〜９９重量％、好ましくは４０〜９５重量％、特に好ましくは５０〜９０重量％の添加量で用いられる。アルカリ可溶性の高分子化合物の添加量が３０重量％未満であると画像記録層の耐久性が悪化し、また、９９重量％を越えると感度、耐久性の両面で好ましくない。
また、フェノール性水酸基を有する樹脂と特定の共重合体とからなるアルカリ可溶性の高分子化合物を含む画像形成層は、２層に分けた層構造としてもよいし、又はそれ以上の層に分けて重層構造にしてもかまわない。
【００８５】
［光を吸収し熱を発生する物質］
本発明における光を吸収し熱を発生する物質は、オーバーコート層の構成成分として挙げられた光熱変換剤と同様の顔料や染料を用いることができる。
画像形成層中に含まれる光を吸収し熱を発生する物質としても、赤外光、もしくは近赤外光を吸収する顔料や染料が、赤外光もしくは近赤外光を発光するレーザでの利用に適する点で特に好ましい。
【００８６】
これらの顔料もしくは染料は、印刷版材料全固形分に対し０．０１〜５０重量％、好ましくは０．１〜１０重量％、染料の場合特に好ましくは０．５〜１０重量％、顔料の場合特に好ましくは３．１〜１０重量％の割合で印刷版材料中に添加することができる。顔料もしくは染料の添加量が０．０１重量％未満であると感度が低くなり、また５０重量％を越えると感光層の均一性が失われ、画像記録層の耐久性が悪くなる。これらの染料もしくは顔料は他の成分と同一の層に添加してもよいし、別の層を設けそこへ添加してもよい。また、染料もしくは顔料と結着樹脂は同一の層が好ましいが、別の層でも構わない。
【００８７】
［その他の成分］
本発明における画像記録層を形成するにあたっては、上記のそれぞれの必須成分の他、本発明の効果を損なわない限りにおいて、更に必要に応じて、種々の添加剤を添加することができる。
例えば、オニウム塩、ｏ−キノンジアジド化合物、芳香族スルホン化合物、芳香族スルホン酸エステル化合物等の熱分解性であり、分解しない状態ではアルカリ水可溶性高分子化合物の溶解性を実質的に低下させる物質を併用することは、画像部の現像液への溶解阻止性の向上を図る点では、好ましい。オニウム塩としてはジアゾニウム塩、アンモニウム塩、ホスホニウム塩、ヨードニウム塩、スルホニウム塩、セレノニウム塩、アルソニウム塩等を挙げることができる。
【００８８】
本発明において用いられるオニウム塩として、好適なものとしては、例えば、Ｓ．Ｉ．Ｓｃｈｌｅｓｉｎｇｅｒ，Ｐｈｏｔｏｇｒ．Ｓｃｉ．Ｅｎｇ．，１８，３８７（１９７４）、Ｔ．Ｓ．Ｂａｌ　ｅｔ　ａｌ，Ｐｏｌｙｍｅｒ，２１，４２３（１９８０）、特開平５−１５８２３０号公報に記載のジアゾニウム塩、米国特許第４，０６９，０５５号、同４，０６９，０５６号、特開平３−１４０１４０号の明細書に記載のアンモニウム塩、Ｄ．Ｃ．Ｎｅｃｋｅｒ　ｅｔ　ａｌ，Ｍａｃｒｏｍｏｌｅｃｕｌｅｓ，１７，２４６８（１９８４）、Ｃ．Ｓ．Ｗｅｎｅｔ　ａｌ，Ｔｅｈ，Ｐｒｏｃ．Ｃｏｎｆ．Ｒａｄ．Ｃｕｒｉｎｇ　ＡＳＩＡ，ｐ４７８　Ｔｏｋｙｏ，Ｏｃｔ（１９８８）、米国特許第４，０６９，０５５号、同４，０６９，０５６号に記載のホスホニウム塩、Ｊ．Ｖ．Ｃｒｉｖｅｌｌｏ　ｅｔ　ａｌ，Ｍａｃｒｏｍｏｒｅｃｕｌｅｓ，１０（６），１３０７（１９７７）、Ｃｈｅｍ．　＆　Ｅｎｇ．Ｎｅｗｓ，Ｎｏｖ．２８，ｐ３１（１９８８）、欧州特許第１０４，１４３号、米国特許第３３９，０４９号、同第４１０，２０１号、特開平２−１５０８４８号、特開平２−２９６５１４号に記載のヨードニウム塩、Ｊ．Ｖ．Ｃｒｉｖｅｌｌｏ　ｅｔ　ａｌ，Ｐｏｌｙｍｅｒ　Ｊ．１７，７３（１９８５）、Ｊ．Ｖ．Ｃｒｉｖｅｌｌｏ　ｅｔ　ａｌ．Ｊ．Ｏｒｇ．Ｃｈｅｍ．，４３，３０５５（１９７８）、Ｗ．Ｒ．Ｗａｔｔ　ｅｔ　ａｌ，Ｊ．Ｐｏｌｙｍｅｒ　Ｓｃｉ．，Ｐｏｌｙｍｅｒ　Ｃｈｅｍ．Ｅｄ．，２２，１７８９（１９８４）、Ｊ．Ｖ．Ｃｒｉｖｅｌｌｏ　ｅｔ　ａｌ，Ｐｏｌｙｍｅｒ　Ｂｕｌｌ．，１４，２７９（１９８５）、Ｊ．Ｖ．Ｃｒｉｖｅｌｌｏ　ｅｔ　ａｌ，Ｍａｃｒｏｍｏｒｅｃｕｌｅｓ，１４（５），１１４１（１９８１）、Ｊ．Ｖ．Ｃｒｉｖｅｌｌｏ　ｅｔ　ａｌ，Ｊ．Ｐｏｌｙｍｅｒ　Ｓｃｉ．，Ｐｏｌｙｍｅｒ　Ｃｈｅｍ．Ｅｄ．，１７，２８７７（１９７９）、欧州特許第３７０，６９３号、同２３３，５６７号、同２９７，４４３号、同２９７，４４２号、米国特許第４，９３３，３７７号、同３，９０２，１１４号、同４１０，２０１号、同３３９，０４９号、同４，７６０，０１３号、同４，７３４，４４４号、同２，８３３，８２７号、独国特許第２，９０４，６２６号、同３，６０４，５８０号、同３，６０４，５８１号に記載のスルホニウム塩、Ｊ．Ｖ．Ｃｒｉｖｅｌｌｏ　ｅｔ　ａｌ，Ｍａｃｒｏｍｏｒｅｃｕｌｅｓ，１０（６），１３０７（１９７７）、Ｊ．Ｖ．Ｃｒｉｖｅｌｌｏ　ｅｔ　ａｌ，Ｊ．Ｐｏｌｙｍｅｒ　Ｓｃｉ．，Ｐｏｌｙｍｅｒ　Ｃｈｅｍ．Ｅｄ．，１７，１０４７（１９７９）に記載のセレノニウム塩、Ｃ．Ｓ．Ｗｅｎ　ｅｔ　ａｌ，Ｔｅｈ，Ｐｒｏｃ．Ｃｏｎｆ．Ｒａｄ．Ｃｕｒｉｎｇ　ＡＳＩＡ，ｐ４７８　Ｔｏｋｙｏ，Ｏｃｔ（１９８８）に記載のアルソニウム塩等があげられる。
オニウム塩の中でも、ジアゾニウム塩が特に好ましい。また、特に好適なジアゾニウム塩としては特開平５−１５８２３０号公報記載のものがあげられる。
【００８９】
オニウム塩の対イオンとしては、四フッ化ホウ酸、六フッ化リン酸、トリイソプロピルナフタレンスルホン酸、５−ニトロ−ｏ−トルエンスルホン酸、５−スルホサリチル酸、２，５−ジメチルベンゼンスルホン酸、２，４，６−トリメチルベンゼンスルホン酸、２−ニトロベンゼンスルホン酸、３−クロロベンゼンスルホン酸、３−ブロモベンゼンスルホン酸、２−フルオロカプリルナフタレンスルホン酸、ドデシルベンゼンスルホン酸、１−ナフトール−５−スルホン酸、２−メトキシ−４−ヒドロキシ−５−ベンゾイル−ベンゼンスルホン酸、及びパラトルエンスルホン酸等を挙げることができる。これらの中でも特に六フッ化リン酸、トリイソプロピルナフタレンスルホン酸や２，５−ジメチルベンゼンスルホン酸のごときアルキル芳香族スルホン酸が好適である。
【００９０】
好適なキノンジアジド類としてはｏ−キノンジアジド化合物を挙げることができる。本発明に用いられるｏ−キノンジアジド化合物は、少なくとも１個のｏ−キノンジアジド基を有する化合物で、熱分解によりアルカリ可溶性を増すものであり、種々の構造の化合物を用いることができる。つまり、ｏ−キノンジアジドは熱分解により結着剤の溶解抑制能を失うことと、ｏ−キノンジアジド自身がアルカリ可溶性の物質に変化することの両方の効果により感材系の溶解性を助ける。本発明に用いられるｏ−キノンジアジド化合物としては、例えば、Ｊ．コーサー著「ライト−センシティブ・システムズ」（Ｊｏｈｎ　Ｗｉｌｅｙ　＆　Ｓｏｎｓ．Ｉｎｃ．）第３３９〜３５２頁に記載の化合物が使用できるが、特に種々の芳香族ポリヒドロキシ化合物あるいは芳香族アミノ化合物と反応させたｏ−キノンジアジドのスルホン酸エステル又はスルホン酸アミドが好適である。また、特公昭４３−２８４０３号公報に記載されているようなベンゾキノン（１，２）−ジアジドスルホン酸クロライド又はナフトキノン−（１，２）−ジアジド−５−スルホン酸クロライドとピロガロール−アセトン樹脂とのエステル、米国特許第３，０４６，１２０号及び同第３，１８８，２１０号に記載されているベンゾキノン−（１，２）−ジアジドスルホン酸クロライド又はナフトキノン−（１，２）−ジアジド−５−スルホン酸クロライドとフェノール−ホルムアルデヒド樹脂とのエステルも好適に使用される。
【００９１】
更に、ナフトキノン−（１，２）−ジアジド−４−スルホン酸クロライドとフェノールホルムアルデヒド樹脂あるいはクレゾール−ホルムアルデヒド樹脂とのエステル、ナフトキノン−（１，２）−ジアジド−４−スルホン酸クロライドとピロガロール−アセトン樹脂とのエステルも同様に好適に使用される。その他の有用なｏ−キノンジアジド化合物としては、数多くの特許に報告され知られている。例えば、特開昭４７−５３０３号、特開昭４８−６３８０２号、特開昭４８−６３８０３号、特開昭４８−９６５７５号、特開昭４９−３８７０１号、特開昭４８−１３３５４号、特公昭４１−１１２２２号、特公昭４５−９６１０号、特公昭４９−１７４８１号、米国特許第２，７９７，２１３号、同第３，４５４，４００号、同第３，５４４，３２３号、同第３，５７３，９１７号、同第３，６７４，４９５号、同第３，７８５，８２５号、英国特許第１，２２７，６０２号、同第１，２５１，３４５号、同第１，２６７，００５号、同第１，３２９，８８８号、同第１，３３０，９３２号、ドイツ特許第８５４，８９０号などの各明細書中に記載されているものをあげることができる。
【００９２】
ｏ−キノンジアジド化合物の添加量は好ましくは印刷版材料全固形分に対し、１〜５０質量％、更に好ましくは５〜３０質量％、特に好ましくは１０〜３０質量％の範囲である。これらの化合物は単一で使用できるが、数種の混合物として使用してもよい。
【００９３】
また、感度を更に向上させる目的で、環状酸無水物類、フェノール類、有機酸類を併用することもできる。環状酸無水物としては米国特許第４，１１５，１２８号明細書に記載されている無水フタル酸、テトラヒドロ無水フタル酸、ヘキサヒドロ無水フタル酸、３，６−エンドオキシ−テトラヒドロ無水フタル酸、テトラクロル無水フタル酸、無水マレイン酸、クロル無水マレイン酸、α−フェニル無水マレイン酸、無水コハク酸、無水ピロメリット酸などが使用できる。フェノール類としては、ビスフェノールＡ、ｐ−ニトロフェノール、ｐ−エトキシフェノール、２，４，４’−トリヒドロキシベンゾフェノン、２，３，４−トリヒドロキシベンゾフェノン、４−ヒドロキシベンゾフェノン、４，４’，４’’−トリヒドロキシトリフェニルメタン、４，４’，３’’，４’’−テトラヒドロキシ−３，５，３’，５’−テトラメチルトリフェニルメタンなどが挙げられる。更に、有機酸類としては、特開昭６０−８８９４２号、特開平２−９６７５５号公報などに記載されている、スルホン酸類、スルフィン酸類、アルキル硫酸類、ホスホン酸類、リン酸エステル類及びカルボン酸類などがあり、具体的には、ｐ−トルエンスルホン酸、ドデシルベンゼンスルホン酸、ｐ−トルエンスルフィン酸、エチル硫酸、フェニルホスホン酸、フェニルホスフィン酸、リン酸フェニル、リン酸ジフェニル、安息香酸、イソフタル酸、アジピン酸、ｐ−トルイル酸、３，４−ジメトキシ安息香酸、フタル酸、テレフタル酸、４−シクロヘキセン−１，２−ジカルボン酸、エルカ酸、ラウリン酸、ｎ−ウンデカン酸、アスコルビン酸などが挙げられる。
上記の環状酸無水物、フェノール類及び有機酸類の印刷版材料中に占める割合は、０．０５〜２０質量％が好ましく、より好ましくは０．１〜１５質量％、特に好ましくは０．１〜１０質量％である。
【００９４】
また、本発明に係る画像記録層塗布液中には、現像条件に対する処理の安定性を広げるため、特開昭６２−２５１７４０号公報や特開平３−２０８５１４号公報に記載されているような非イオン界面活性剤、特開昭５９−１２１０４４号公報、特開平４−１３１４９号公報に記載されているような両性界面活性剤、ＥＰ９５０５１７公報に記載されているようなシロキサン系化合物、特開平１１−２８８０９３号公報に記載されているようなフッ素含有のモノマー共重合体を添加することができる。
非イオン界面活性剤の具体例としては、ソルビタントリステアレート、ソルビタンモノパルミテート、ソルビタントリオレート、ステアリン酸モノグリセリド、ポリオキシエチレンノニルフェニルエーテル等が挙げられる。両性活性剤の具体例としては、アルキルジ（アミノエチル）グリシン、アルキルポリアミノエチルグリシン塩酸塩、２−アルキル−Ｎ−カルボキシエチル−Ｎ−ヒドロキシエチルイミダゾリニウムベタインやＮ−テトラデシル−Ｎ，Ｎ−ベタイン型（例えば、商品名「アモーゲンＫ」：第一工業（株）製）等が挙げられる。
シロキサン系化合物としては、ジメチルシロキサンとポリアルキレンオキシドのブロック共重合体が好ましく、具体例として、（株）チッソ社製、ＤＢＥ−２２４，ＤＢＥ−６２１，ＤＢＥ−７１２，ＤＢＰ−７３２，ＤＢＰ−５３４、独Ｔｅｇｏ社製、Ｔｅｇｏ　Ｇｌｉｄｅ１００等のポリアルキレンオキシド変性シリコーンを挙げることが出来る。
上記非イオン界面活性剤及び両性界面活性剤の印刷版材料中に占める割合は、０．０５〜１５質量％が好ましく、より好ましくは０．１〜５質量％である。
【００９５】
本発明における画像記録層中には、露光による加熱後直ちに可視像を得るための焼き出し剤や、画像着色剤としての染料や顔料を加えることができる。
焼き出し剤としては、露光による加熱によって酸を放出する化合物（光酸放出剤）と塩を形成し得る有機染料の組合せを代表として挙げることができる。具体的には、特開昭５０−３６２０９号、同５３−８１２８号の各公報に記載されているｏ−ナフトキノンジアジド−４−スルホン酸ハロゲニドと塩形成性有機染料の組合せや、特開昭５３−３６２２３号、同５４−７４７２８号、同６０−３６２６号、同６１−１４３７４８号、同６１−１５１６４４号及び同６３−５８４４０号の各公報に記載されているトリハロメチル化合物と塩形成性有機染料の組合せを挙げることができる。かかるトリハロメチル化合物としては、オキサゾール系化合物とトリアジン系化合物とがあり、どちらも経時安定性に優れ、明瞭な焼き出し画像を与える。
【００９６】
画像の着色剤としては、前述の塩形成性有機染料以外に他の染料を用いることができる。塩形成性有機染料を含めて、好適な染料として油溶性染料と塩基性染料をあげることができる。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）などを挙げることができる。また、特開昭６２−２９３２４７号公報に記載されている染料は特に好ましい。これらの染料は、印刷版材料全固形分に対し、０．０１〜１０質量％、好ましくは０．１〜３質量％の割合で印刷版材料中に添加することができる。更に、本発明の画像記録層中には必要に応じ、塗膜の柔軟性等を付与するために可塑剤が加えられる。例えば、ブチルフタリル、ポリエチレングリコール、クエン酸トリブチル、フタル酸ジエチル、フタル酸ジブチル、フタル酸ジヘキシル、フタル酸ジオクチル、リン酸トリクレジル、リン酸トリブチル、リン酸トリオクチル、オレイン酸テトラヒドロフルフリル、アクリル酸又はメタクリル酸のオリゴマー及びポリマー等が用いられる。
【００９７】
＜支持体＞
本発明の平版印刷版原版に使用される支持体としては、寸度的に安定な板状物が用いられる。紙、親油性のプラスチック（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、ニッケル、ステンレス鋼板等）、プラスチックフィルム（例えば、二酢酸セルロース、三酢酸セルロース、プロピオン酸セルロース、酪酸セルロース、酢酸酪酸セルロース、硝酸セルロース、ポリエチレンテレフタレート、ポリエチレン、ポリスチレン、ポリプロピレン、ポリカーボネート、ポリビニルアセタール等）、上記の金属がラミネート又は蒸着された紙もしくはプラスチックフィルム等が含まれる。
中でも、好ましくは、ポリエチレンテレフタレートフィルム、ポリカーボネイトフィルム、アルミニウム又は鋼板、もしくは親油性のプラスチックフィルムがラミネートされているアルミニウム又は鋼板である。
【００９８】
本発明に好ましく使用されるアルミニウム板としては、従来より公知公用の素材のアルミニウム板を、適宜、利用することができる。
アルミニウム板を使用するに先立ち、（ａ）現像後に非画像部となる表面の親水性の向上、（ｂ）印刷時の保水性を向上、（ｃ）表面の耐摩耗性の向上や（ｄ）その上に塗布するものとの接着性を確保などのために、表面処理を行うことが好ましい。表面処理には、粗面化、陽極酸化処理、ケイ酸塩処理、下塗りなど、種々の技術が知られており、本発明に用いるアルミニウム支持体は、それらの公知公用のアルミニウム板表面処理技術を適宜利用することができる。
【００９９】
＜平版印刷版原版の製造方法＞
本発明の平版印刷版原版は、上述の支持体上に、通常上記各成分を溶媒に溶かして塗布することにより画像記録層を形成し、その上に上記オーバーコート層を形成することで製造される。
ここで使用する溶媒としては、エチレンジクロライド、シクロヘキサノン、メチルエチルケトン、メタノール、エタノール、プロパノール、エチレングリコールモノメチルエーテル、１−メトキシ−２−プロパノール、２−メトキシエチルアセテート、１−メトキシ−２−プロピルアセテート、ジメトキシエタン、乳酸メチル、乳酸エチル、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ，Ｎ−ジメチルホルムアミド、テトラメチルウレア、Ｎ−メチルピロリドン、ジメチルスルホキシド、スルホラン、γ−ブチロラクトン、トルエン等をあげることができるがこれに限定されるものではない。これらの溶媒は単独あるいは混合して使用される。
溶媒中の上記成分（添加剤を含む全固形分）の濃度は、好ましくは１〜５０重量％である。
また塗布、乾燥後に得られる支持体上の塗布量（固形分）は、用途によって異なるが、感光性印刷版についていえば一般的に０．５〜５．０ｇ／ｍ^２が好ましい。塗布量が少なくなるにつれて、見かけの感度は大になるが、感光膜の皮膜特性は低下する。
塗布する方法としては、種々の方法を用いることができるが、例えば、バーコーター塗布、回転塗布、スプレー塗布、カーテン塗布、ディップ塗布、エアーナイフ塗布、ブレード塗布、ロール塗布等を挙げることができる。
【０１００】
＜画像形成＞
本発明の感熱性の平版印刷版原版は熱により画像形成される。具体的には、熱記録ヘッド等による直接画像様記録、赤外線レーザによる走査露光、キセノン放電灯などの高照度フラッシュ露光や赤外線ランプ露光などが用いられるが、波長７００〜１２００ｎｍの赤外線を放射する半導体レーザ、ＹＡＧレーザ等の固体高出力赤外線レーザによる露光が好適である。
【０１０１】
フェノール性水酸基を有すアルカリ可溶性樹脂を分子間相互作用で溶解阻止してアルカリ不溶性の層とし、画像状エネルギー照射による光分解反応又は熱による分子間相互作用の破壊でアルカリ可溶性に変換し、それを現像して画像形成する仕組みのポジ型印刷版において、現像液は、通常、アルカリ性水溶液が用いられる。原理的には同じ本発明の印刷版原版も、同様に、アルカリ性水溶液で現像される。
【０１０２】
このアルカリ性現像液は、アルカリ剤を主成分とし、その他に界面活性剤、硬水軟化剤、防腐剤、消泡剤などが必要に応じて添加されている。
アルカリ剤としては、例えば、ケイ酸ナトリウム、同カリウム、第３リン酸ナトリウム、同カリウム、同アンモニウム、第２リン酸ナトリウム、同カリウム、同アンモニウム、炭酸ナトリウム、同カリウム、同アンモニウム、炭酸水素ナトリウム、同カリウム、同アンモニウム、水酸化ナトリウム、同アンモニウム、同カリウム及び同リチウムなどの無機アルカリ塩が挙げられる。また、モノエタノールアミン、ジエタノールアミン、トリエタノールアミン、モノイソプロパノールアミン、ジイソプロパノールアミンなどの有機アルカリ剤も用いられる。これらのアルカリ剤は単独もしくは２種以上を組み合わせて用いられる。
【０１０３】
これらのアルカリ剤の中で特に好ましいのは、ケイ酸ナトリウム、ケイ酸カリウム等である。その理由は、ケイ酸塩の成分である酸化ケイ素ＳｉＯ_２とアルカリ金属酸化物Ｍ_２Ｏの比率と濃度によってある程度現像性の調節が可能となるためである。また、ほとんど全てのポジ型感光性平版印刷版が現像にｐＨ１３前後の強アルカリを必要とし、ケイ酸塩がそのｐＨ領域で良好な緩衝作用を示し、安定した現像が可能だからである。本発明の平版印刷版原版は、上記の良く知られたケイ酸塩を主成分とするアルカリ現像液で現像することができる。
【０１０４】
特開平８−１６０６３１号公報、同８−３０５０３９号公報には、糖類、水酸化ナトリウム及び炭酸ナトリウムを主成分とし、ケイ酸塩を含まないｐＨ１１．０〜１３．５あるいはｐＨ９．０〜１３．５の範囲の現像液が開示されている。これらの公報で開示された現像液を用いれば、ケイ酸塩を含む現像液の問題点、すなわち、アルカリ性領域では安定であるが、中性ではゲル化し、また、蒸発乾固するとフッ化水素酸のような強酸にしか溶けなくなり、不溶物付着による自動現像機の汚染や現像補充用センサーの作動不良あるいは現像廃液処理の際の不溶物析出による処理作業の妨害などの問題点を、解消できると述べられている。本発明の平版印刷版原版は、このようなケイ酸塩を含まないアルカリ性現像液でも好適に現像することができる。
【０１０５】
本発明の平版印刷版原版は、現像後、従来の平版印刷版原版と同様に、水洗又はリンス及び／又はガム引き、必要な場合には画像部の消去が行なわれる。このようにして得られた平版印刷版は、印刷工程に供することができる。
【０１０６】
【実施例】
以下、本発明を以下の実施例に従って説明するが、本発明の範囲はこれらの実施例に限定されない。
【０１０７】
［実施例１〜７］
〔アルミニウム基板の作製〕
厚み０．２４ｍｍのアルミニウム板（材質１０５０）を、ナイロンブラシと４００メッシュのパミストン水懸濁液を用いてその表面を砂目立てし、水でよく洗浄した。この板を１５％水酸化ナトリウム水溶液に浸してエッチングをした後、水洗した。更に１％硝酸で中和し、次に０．７％硝酸水溶液中で矩形波交番波形電流を用い、１６０クーロン／ｄｍ^２の陽極時電気量で電解粗面化処理を行った。水洗後、１０％水酸化ナトリウム水溶液中に浸してエッチングした後、水洗した。次に３０％硫酸水溶液中に浸してデスマットした後、水洗した。更に、２０％硫酸水溶液中で直流電流を用いて陽極酸化処理を行い、酸化皮膜量２．７ｇ／ｍ^２とした。更に、ケイ酸ナトリウム０．５重量％水溶液で３０℃で１０秒間処理した後、下記下塗り液を塗布し、塗膜を８０℃で１５秒間乾燥し基板を得た。乾燥後の塗膜の被覆量は４．５ｍｇ／ｍ^２であった。
【０１０８】
（下塗り液）
下記化合物　　　　　　　　　　　　　　　　　　　　　　・・・０．３ｇ
メタノール　　　　　　　　　　　　　　　　　　　　・・・１００ｇ
水　　　　　　　　　　　　　　　　　　　　　　　　　　・・・１ｇ
【０１０９】
【化５】

【０１１０】
〔画像記録層の形成〕
得られた支持体に、以下の画像記録層用塗布液Ａを塗布量１．０ｇ／ｍ^２になるよう塗布したのち、ＴＡＢＡＩ社製、ＰＥＲＦＥＣＴ　ＯＶＥＮ　ＰＨ２００にてＷｉｎｄ　Ｃｏｎｔｒｏｌを７に設定して１４０度で５０秒間乾燥し、画像記録層を形成した。
【０１１１】

【０１１２】
【化６】

【０１１３】
〔オーバーコート層の形成〕
その後、上記の画像記録層Ａを塗布した基板上に、下記組成のオーバーコート層塗布液を液量７．５ｃｃ／ｍ^２となるように塗布し、８０℃２分乾燥させて乾燥重量０．１ｇ／ｍ^２のオーバーコート層を有する、実施例１〜７におけるポジ型平版印刷版原版１〜７を作製した。
【０１１４】
（オーバーコート層塗布液）
・ポリアクリル酸　　　　　　　　　　　　　　　　　　　・・・７．０４ｇ
（Ａｌｄｒｉｃｈ製、Ｍｗ：１０００、５％水溶液）
・下記表１に記載の特定有機粒子又は無機粒子の分散物　　・・・２．００ｇ
（分散質の含有量２０％）
・蒸留水　　　　　　　　　　　　　　　　　　　　　　・・・１７．２８ｇ
・イソプロピルアルコール　　　　　　　　　　　　　　　・・・２．７２ｇ
【０１１５】
［実施例８］
実施例１〜７で用いたものと同じ、下塗り層が設けられた支持体に、以下の画像記録層用塗布液Ｂを塗布量０．９ｇ／ｍ^２になるよう塗布、乾燥させて、画像記録層Ｂを形成した。
【０１１６】

【０１１７】
更に、この画像記録層Ｂ上に、以下の画像記録層用塗布液Ｃを塗布量０．３ｇ／ｍ^２になるよう塗布し、乾燥させて、画像記録層Ｃを形成した。
【０１１８】
（画像記録層用塗布液Ｃ）
・プロピレングリコールモノメチルエーテル　　　　　　・・・１２．８７ｇ
・ｍ，ｐ−クレゾールノボラック　　　　　　　　　　　　・・・０．２１ｇ
（ｍ／ｐ＝６／４　Ｍｗ３，５００）
・フッ素界面活性剤　　　　　　　　　　　　　　　　　　・・・０．０１ｇ
（メガファックＦ−１７６、大日本インキ製　２０％）
・下記構造の赤外線吸剤（１）　　　　　　　　　　　　　・・・０．０２ｇ
・ブチルメタクリレート／エチルメタクリレート／メタクリル酸・０．０２ｇ
（３７／３７／２６　Ｍｗ４９，０００）
【０１１９】
その後、上記の画像記録層Ｃを塗布した基板上に、実施例１〜７と同じ組成のオーバーコート層塗布液を塗布し、乾燥させて、実施例８におけるポジ型平版印刷版原版８を作製した。
【０１２０】
［比較例１及び２］
画像記録層Ａの表面にオーバーコート層を塗布しなかったものを比較例１の平版印刷版原版とした。
また、オーバーコート層塗布液から、特定有機粒子又は無機粒子を除いた塗布液を調製し、その調製液を画像記録層Ａの表面に液量７．５ｃｃ／ｍ^２となるように塗布し、８０℃２分乾燥させて乾燥重量０．１ｇ／ｍ^２のオーバーコート層を形成したものを比較例２の平版印刷版原版とした。
【０１２１】
［比較例８］
実施例８において、画像記録層Ｃの表面にオーバーコート層を塗布しなかったものを比較例３の平版印刷版原版とした。
【０１２２】
〔平版印刷版原版の評価〕
上記のように作製した各平版印刷版原版を、カナダＣＲＥＯ社製トレンドセッター（４０Ｗの８３０ｎｍ半導体レーザーを搭載したプレートセッター）に取り付け画像様に露光した。次いで、富士写真フィルム製ＰＳプロセッサー９４０Ｈを用いて現像した。現像液は、富士写真フイルム（株）製のＤＴ−１（１：８）を３０℃１２秒で用いた。フィニシャー液は、富士写真フイルム（株）製ＦＰ−２Ｗ（１：１）を用いた。
【０１２３】
（耐溶剤性、耐刷性）
現像した平版印刷版をもちいて、小森印刷機スプリントで上質紙に印刷した。５０００枚印刷毎にクリーナー液（富士写真フィルム（株）製　プレートクリーナＣＬ２）で版面を拭きながら印刷した。ここで、最終印刷枚数とは、平版印刷版の画像形成層が膜減りを起こし、部分的にインキがつかなくなる、いわゆる版飛びを起こすまでの、良好な画像が得られた枚数である。この枚数が多いほど耐刷性に優れると評価する。
【０１２４】
（経時安定性評価）
作成した平版印刷版原版を４５℃、相対湿度７５％の高温高湿下に３日間保管した。この経時保存後の平版印刷版原版について、前記プレートセッターで露光して最低画像形成可能エネルギー量を測定した。また、この高温高湿下での保存を実施する前の平版印刷版原版についてもこのエネルギー量を測定し、両者の差、即ち、強制経時前後の感度変動の比較をすることにより評価した。両者の数値の差が少ないほど経時安定性に優れる。
【０１２５】
（印刷用の塗布膜強度の評価）
塗布膜強度の評価は、直径１．０ｍｍφのサファイア針を持つ引掻き試験機にて荷重を変えて引掻きを行い、現像後、引掻いた部分で傷が付かなかった最大荷重を求めて行った。
【０１２６】
（有機粒子のガラス転移点Ｔｇ）
実施例１〜４、及び実施例８において用いた特定有機粒子分散液中の、特定有機粒子のガラス転移点Ｔｇを以下の方法で測定した。
まず、実施例１〜４、及び実施例８において用いた特定有機粒子分散液を乾燥して、固形分のみ取り出した後、１０ｍｇについて、セイコーインスツルメンツ社製示差走査熱量計（ＤＳＣ２００）及び熱分析システム（ＳＳＣ５１００）を用いて、２５℃から２３０℃まで１０℃／ｍｉｎで昇温し、熱量を測定した。その結果、いずれの有機粒子においても、特徴的なピークは見られなかった。更に、同条件にて、示差熱熱重量同時測定計（ＴＧ／ＤＴＡ）を用い、測定を行ったところ、こちらにおいても特徴的なピークは見られなかった。従って、本実施例において用いられる特定有機粒子のガラス転移点Ｔｇは、いずれも、２００℃以上であることが判明した。
【０１２７】
【表１】

【０１２８】
表１より明らかなように、本発明の平版印刷版原版は、膜強度、耐刷性に優れ、高温高湿度化での感度変動が抑制され、保存安定性に優れることがわかる。
【０１２９】
【発明の効果】
本発明によれば、耐溶剤性及び現像ラチチュードに優れると共に、耐傷性及び高温高湿などの環境下においても耐刷性やハンドリング性が低下しない保存安定性の改善された平版印刷版原版を提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat-sensitive positive lithographic printing plate precursor. More specifically, the present invention relates to a positive lithographic printing plate precursor capable of recording an image by infrared laser exposure based on a digital signal and capable of developing the recorded image with an alkaline developer.
[0002]
[Prior art]
In a known positive lithographic printing plate material for infrared laser for direct plate making, an alkaline aqueous solution-soluble resin having a phenolic hydroxyl group such as a novolak resin is used as the alkaline aqueous solution-soluble polymer compound. For example, as such a recording material, in Japanese Patent Application Laid-Open No. 7-285275, a substance (photothermal conversion agent) that absorbs light and generates heat in an aqueous alkali-soluble resin having a phenolic hydroxyl group such as a novolak resin, An image recording material to which an onium salt, a quinonediazide compound or the like is added has been proposed. In such image recording materials, onium salts, quinonediazide compounds, and the like function as dissolution inhibitors that substantially lower the solubility of the aqueous alkali-soluble resin, but the dissolution inhibitor is decomposed by heat generation in the exposed portion. It is possible to dissolve and form an image.
However, this image recording material has the inconvenience that onium salts, quinonediazide compounds, and the like have a light absorption region (350 to 500 nm) in the visible region, so that the place of handling is limited to yellow wrinkles. In addition, if stains occur during printing or the plate is reused after printing, it is necessary to clean the plate surface with a solvent such as a cleaner solution.However, novolac resin has low solvent resistance, and the cleaner solution must be removed during printing. When used, there is a problem that printing durability is lowered.
[0003]
As a technique for solving this problem, JP-A-11-44956 discloses a copolymer containing 10 mol% or more of at least one of the following (a) to (c) as a copolymer component on a support. (A), an aqueous alkaline solution-soluble resin (B) having a phenolic hydroxyl group and a photothermal conversion agent, and the mixing weight ratio of the copolymer (A) and the aqueous alkaline solution-soluble resin (B) is from 50:50 to 95: 5. A positive photosensitive composition for infrared lasers having a layer in the range is disclosed.
(A) a monomer having a sulfonamide group in which at least one hydrogen atom is bonded to a nitrogen atom;
(B) -CO-NH-SO ₂ Monomer having an active imino group represented by-
(C) Acrylamide, methacrylamide, acrylic ester, methacrylic ester or hydroxystyrene each having a phenolic hydroxyl group
Although it has been shown that this photosensitive composition greatly improves the solvent resistance and development latitude, the lithographic printing plate precursor provided with this photosensitive composition has sufficient mechanical film strength of the image recording layer. In addition, there was a problem that the plate surface was easily damaged during handling, and the sensitivity decreased with time.
[0004]
Therefore, Japanese Patent Laid-Open No. 2001-14222 attempts to improve scratch resistance by providing a water-soluble overcoat layer on the surface of the image recording layer. Although the scratch resistance is improved to some extent by the presence of the overcoat layer, the water-soluble resin used here is not sufficiently adhered to the hydrophobic image recording layer and has a hygroscopic property, so When stored in, the surface becomes sticky and the handling property decreases, the adhesion between the overcoat layer and the image forming layer changes, the solubility in alkali during development changes, and the sensitivity becomes unstable. It became clear that there are concerns about
Furthermore, the heat generated during exposure is dissipated to the overcoat layer made of a water-soluble resin, so that the solubilization of the image forming layer in the exposed portion with respect to the alkaline developer is not promoted, and as a result, the sensitivity itself is also lowered. Also had.
[0005]
Various techniques have been proposed as an overcoat layer and a protective layer for protecting the image recording layer. For example, Japanese Patent Application Laid-Open No. 11-194483 discloses an infrared-sensitive SiO layer as the uppermost layer. ₂ And a method for producing a lithographic printing plate having a layer that is impermeable to the developer, and WO99 / 67097 describes that a water-insoluble polymer layer having a pH of 6 or more is provided as the uppermost layer. ing. However, these uppermost layers are not soluble in alkali, and cannot be applied to a positive image recording layer as in the present invention from the viewpoint of developability.
Japanese Patent Laid-Open No. 10-250255 describes the upper layer in which the water permeability and / or solubility is increased or decreased, but the water permeability and solubility of the overcoat layer of this patent fluctuate due to light or heat. There is a concern that developability fluctuates due to light and heat. Furthermore, WO02 / 14071 describes an ink-accepting uppermost layer that does not contain a photothermal conversion agent that serves as a dissolution inhibitor, but such an overcoat layer may result in insufficient exposure area removal. There is.
As described above, the known overcoat layer and protective layer are applied to the positive type lithographic printing plate precursor as in the present invention, while maintaining high developability and image formability, and effective scratch resistance and storage stability. It is the present situation that cannot be achieved.
[0006]
[Problems to be solved by the invention]
Therefore, an object of the present invention is to solve the above-mentioned problems, and it is excellent in solvent resistance and development latitude, and is not preserved in printing resistance and handling properties even in an environment such as scratch resistance and high temperature and high humidity. An object of the present invention is to provide a positive planographic printing plate precursor having improved stability.
[0007]
[Means for Solving the Problems]
The present inventor has found that the above problem can be solved by providing an overcoat layer containing organic particles or inorganic particles having a specific glass transition point that can be easily dissolved or dispersed in an alkaline aqueous solution. The invention has been completed.
[0008]
That is, the positive planographic printing plate precursor of the present invention is formed on a support,
An image recording layer containing a substance that absorbs light and generates heat, and an aqueous alkali-soluble compound having a phenolic hydroxyl group;
An overcoat layer containing organic particles having an alkali water-soluble or alkali-liquid dispersibility glass transition point Tg of 200 ° C. or higher, or alkali water-soluble or alkali-liquid dispersible inorganic particles;
Are sequentially provided.
[0009]
Here, that the overcoat layer is alkali-water-soluble or alkali-liquid dispersible preferably means that the overcoat layer is soluble or dispersible in an alkaline aqueous solution having a pH of 8 or higher.
The overcoat layer preferably further contains a photothermal conversion agent.
This overcoat layer is formed by coating the surface of the image recording layer with a dispersion containing organic particles or glass particles having a glass transition point Tg of 200 ° C. or higher as a dispersoid.
[0010]
The organic particles may be selected from the group consisting of acrylic polymers, epoxy polymers, styrene polymers, urethane polymers, phenol polymers, vinyl ester polymers, and derivatives thereof. preferable.
The organic particles preferably have a core-shell structure. In this structure, the core portion is an acrylic polymer, epoxy polymer, styrene polymer, urethane polymer, phenol polymer, vinyl ester. Preferably, the shell part is selected from the group consisting of a resin having an acid group, a resin having an amide group, and a resin having an amino group.
Furthermore, it is a preferable aspect that the inorganic particles are composed of silica, alumina, magnesium oxide, magnesium carbonate, calcium alginate, titanium oxide, zirconium oxide, and a mixture thereof.
[0011]
In the lithographic printing plate precursor according to the invention, as an overcoat layer, organic particles having a glass transition point Tg of 200 ° C. or higher that can be dissolved or dispersed in an alkali water-soluble, or inorganic particles that can be dissolved or dispersed in an alkali-water-soluble material The layer containing is adopted. Since these organic particles and inorganic particles have relatively monodispersibility, a continuous and uniform film can be formed by filling the surface of the image recording layer. In addition, since this film has high rigidity and good resistance to heat, it has excellent stress dispersibility with respect to external force, exhibits good scratch resistance, and has thermal stability. Presumed to be possible.
Further, when storing the planographic printing plate precursor of the present invention, the overcoat layer has excellent adhesion to the image recording layer, and since there is no change in film properties over time due to moisture in the atmosphere, the image recording layer is effective. In the case of recording an image, if an exposure region contains a photothermal conversion agent, an improvement in sensitivity is achieved by heat generation from the photothermal conversion agent, and the dissolution suppression release property of the adjacent image recording layer is excellent. In addition, the hydrophilic support is quickly exposed to become a hydrophilic dampening water receiving area, and in the unexposed area, only the overcoat layer is quickly dissolved or dispersed and removed by the alkaline aqueous solution to expose the image forming layer. In addition, since an ink receptive region is formed, it is considered that a high development latitude can be obtained.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the positive planographic printing plate precursor of the present invention will be described in detail.
The positive-type planographic printing plate precursor of the present invention comprises an image recording layer containing a substance that absorbs light and generates heat, and an aqueous alkali-soluble compound having a phenolic hydroxyl group, and an aqueous alkali-soluble or alkaline liquid. An organic particle having a dispersible glass transition point Tg of 200 ° C. or higher, or an overcoat layer containing inorganic particles having alkali water solubility or alkali liquid dispersibility is sequentially provided.
Hereinafter, the overcoat layer, the image recording layer, and the support constituting the positive type lithographic printing plate precursor according to the invention will be described in detail.
[0013]
<Overcoat layer>
The overcoat layer in the present invention is a layer containing organic particles having a glass transition point Tg of 200 ° C. or higher having alkali water solubility or alkali liquid dispersibility, or inorganic particles having alkali water solubility or alkali liquid dispersibility. It is characterized by that.
The organic particles and inorganic particles contained in the overcoat layer of the present invention have surface hydrophilicity because they are imparted with alkali water solubility or alkali liquid dispersibility. And a dispersion liquid containing inorganic particles as a dispersoid, and when the dispersion liquid is coated on the surface of the image recording layer, after the dispersion medium is removed, the solid particles are mutually bonded by a weak interaction due to the surface hydrophilic group. It can be adsorbed to form a layer. When the overcoat layer in the present invention formed in this way is immersed in an alkali developer, the layers are adsorbed to form a layer, and the interaction between organic particles and inorganic particles is released by an excess solution and developed. It quickly dissolves or disperses in the liquid, and the overcoat layer is easily removed.
Here, “having alkali water solubility or alkali liquid dispersibility” preferably means having solubility or dispersibility in an aqueous alkali solution having a pH of 8 or higher.
[0014]
[Organic particles having a glass transition point Tg of 200 ° C. or higher]
The organic particles used in the present invention are required to have a glass transition point Tg of 200 ° C. or higher, and more preferably 300 ° C. or higher.
As the organic particles having a glass transition point Tg of 200 ° C. or higher (hereinafter referred to as “specific organic particles”), a polymer having a glass transition point adjusted by controlling the degree of polymerization or causing a crosslinking reaction. It is preferable to use, and specific examples of the polymer include, for example, a styrene polymer, an acrylic polymer, a vinyl polymer, a urethane polymer, an epoxy polymer, a phenol polymer, and the like. However, the present invention is not limited to these examples.
These polymers may be homopolymers or copolymers, but examples of the polymerization component monomers of the homopolymer or copolymer constituting the structural unit include the following (A) The monomer shown to-(J) can be mentioned.
[0015]
(A) Acrylic acid esters. Examples of this monomer group include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, cyclohexyl acrylate, octyl acrylate, phenyl acrylate, benzyl acrylate, (Substituted) acrylic acid esters such as 2-chloroethyl acrylate, 4-hydroxybutyl acrylate, glycidyl acrylate and the like can be mentioned.
(B) Methacrylic acid esters. Examples of this monomer group include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, octyl methacrylate, phenyl methacrylate, benzyl methacrylate, (Substituted) methacrylic acid esters such as 2-chloroethyl methacrylate, 4-hydroxybutyl methacrylate, o-, m- and p-hydroxyphenyl methacrylate, glycidyl methacrylate, and the like.
[0016]
(C) Substituted acrylamides and substituted methacrylamides. Examples of this monomer group include acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-ethyl acrylamide, N-ethyl methacrylamide, N-hexyl acrylamide, N-hexyl methacrylamide, N- Cyclohexylacrylamide, N-cyclohexylmethacrylamide, N-hydroxyethylacrylamide, N-hydroxyethylacrylamide, N-phenylacrylamide, N-phenylmethacrylamide, N-benzylacrylamide, N-benzylmethacrylamide, N-nitrophenylacrylamide, N Acrylamide such as nitrophenylmethacrylamide, N-ethyl-N-phenylacrylamide and N-ethyl-N-phenylmethacrylamide Methacrylamide.
(D) Vinyl ethers. Examples of this monomer group include ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, phenyl vinyl ether and the like.
[0017]
(E) Vinyl esters. Examples of this monomer group include vinyl acetate, vinyl chloroacetate, vinyl butyrate, vinyl benzoate and the like.
(F) Styrenes. Examples of this monomer group include styrene, methylstyrene, chloromethylstyrene, o-, m- and p-hydroxystyrene.
(G) Vinyl ketones. Examples of this monomer group include methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(H) N-containing monomer. Examples of this monomer group include N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile and the like.
[0018]
(J) Unsaturated sulfonamides. Examples of this monomer group include N- (o-aminosulfonylphenyl) acrylamide, N- (m-aminosulfonylphenyl) acrylamide, N- (p-aminosulfonylphenyl) acrylamide, N- [1- (3 -Aminosulfonyl) naphthyl] acrylamide, acrylamides such as N- (2-aminosulfonylethyl) acrylamide, N- (o-aminosulfonylphenyl) methacrylamide, N- (m-aminosulfonylphenyl) methacrylamide, N- ( methacrylamides such as p-aminosulfonylphenyl) methacrylamide, N- [1- (3-aminosulfonyl) naphthyl] methacrylamide, N- (2-aminosulfonylethyl) methacrylamide, and o-aminosulfonylphenyl acrylate , M-Ami Unsaturated sulfonamides such as sulfonic acid esters such as sulfonylphenyl acrylate, p-aminosulfonylphenyl acrylate, 1- (3-aminosulfonylphenylnaphthyl) acrylate, o-aminosulfonylphenyl methacrylate, m-aminosulfonylphenyl methacrylate, p -Aminosulfonylphenyl methacrylate, 1- (3-aminosulfonylphenylnaphthyl) methacrylate and the like can be mentioned.
[0019]
The specific organic particles used in the present invention may be a copolymer of these polymerizable monomers and a polymerizable unsaturated group-containing oligomer.
Examples of such polymerizable unsaturated group-containing oligomers include vinyl-modified polyesters, vinyl-modified polyurethanes, vinyl-modified epoxy resins, and vinyl-modified phenol resins. Specific examples include maleic anhydride, fumaric acid, tetrahydrophthalic anhydride, endomethylenetetrahydromaleic anhydride, α-terpinene maleic anhydride adduct, monoallyl ether of triol, pentaerythrit diallyl ether or allyl glycidyl ether. Examples thereof include those in which a polymerizable unsaturated bond (vinyl group) is introduced by polycondensation or addition of various compounds.
[0020]
Further, as the specific organic particles, those obtained by introducing an acid group into polyester can be used. Here, as a method for introducing an acid group, for example, an excess of a dibasic acid such as phthalic acid is used. In this way, a product having a carboxyl group at the terminal is obtained. As another method, one having an acid group in the main chain can be obtained by using trimellitic anhydride.
[0021]
The vinyl-modified polyurethane can be obtained, for example, by addition polymerization of various polyols and diisocyanates such as glycerol monoallyl ether or butadiene polyol containing 1,2-bond. Alternatively, a vinyl bond is also introduced by an addition reaction between a urethane having an isocyanate group at a terminal and a hydroxyl group-containing polymerizable monomer.
Further, as the specific organic particles, those obtained by introducing acid groups into polyurethane can be used, and acid groups can be introduced by adding dimethylolpropionic acid or the like as a polyol component.
[0022]
Examples of the vinyl-modified epoxy resin include those obtained by reacting a terminal epoxy group of an epoxy resin with a carboxyl group of acrylic acid or methacrylic acid.
[0023]
Examples of the vinyl-modified phenol resin include those obtained by reacting a hydroxyl group of a phenol resin with a (meth) acrylic acid halide or glycidyl (meth) acrylate.
[0024]
Furthermore, as the polymerizable unsaturated group-containing oligomer, polymerizable monomers having a polymerizable vinyl group obtained by adding a glycidyl group-containing polymerizable monomer to a carboxyl group-containing vinyl copolymer. It may be an oligomer. The polymerizable monomers used here are selected from those listed above.
However, the polymerizable unsaturated group-containing oligomer is not limited to the types and methods described above as long as it is an oligomer having a polymerizable vinyl group.
[0025]
By copolymerizing these polymerizable monomers, optionally at least one selected from polymerizable unsaturated group-containing oligomers, and monomers having a hydrophilic group shown below, Specific organic particles used for the coating layer are obtained. The obtained specific organic particles preferably have a weight average molecular weight of 500 to 500,000 and a number average molecular weight of 200 to 60,000.
[0026]
The monomer having a hydrophilic group used in preparing the specific organic particles includes a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a hydroxyl group, an amide group, a sulfonamide group, and an amino group as the hydrophilic group. It is preferable to have. Specific examples of the monomer having a hydrophilic group include, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, monobutyl itaconic acid, monobutyl maleate, acid phosphooxyethyl methacrylate, acid phosphooxy Examples include propyl methacrylate, 3-chloro-2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl methacrylate, acrylamide, N-vinylpyrrolidone, N-vinylimidazole, and hydroxyethyl acrylate.
[0027]
In addition to these, other examples of the specific organic particles used in the present invention include urethane resins, for example, urethane resin dispersions disclosed in JP-B-1-287183, or epoxy resins, for example, Various epoxy compounds as described in 53-1228, 55-3481 or 55-9433 can be mentioned.
[0028]
The overcoat layer of the present invention is formed by coating a dispersion containing specific organic particles or inorganic particles as a dispersoid on the surface of the image forming layer described later.
For example, when an overcoat layer containing specific organic particles is formed, a dispersion using specific organic particles as a dispersoid (specific organic particle dispersion) is preferably prepared using emulsion polymerization or dispersion polymerization. At this time, it is desirable to introduce a substituent having hydrophilicity enough to be easily dispersed in an alkali developer into the monomer or oligomer constituting the specific organic particle.
Particularly preferable methods for preparing the organic particle dispersion include phase inversion emulsification methods, which are described in detail in, for example, JP-A-3-221137, JP-A-5-66600, and JP-A-11-348446. ing.
[0029]
If desired, the dispersion stability of these specific organic particles can be improved by adding a surfactant or a hydrophilic (low molecular weight) compound that can be adsorbed on the surface of the specific organic particles. Such surfactants include anionic, cationic or neutral surfactants. Examples of the hydrophilic compound include hydrophilic polymers or oligomers such as polyvinyl alcohol and polyethylene glycol, aliphatic carboxylic acids, and aliphatic alcohols. In order to apply such a surfactant or hydrophilic compound to the surface of specific organic particles or specific organic particles, the specific organic particles may be added to a dispersion medium in which the specific organic particles are dispersed, but the application method is limited to this. Is not to be done.
[0030]
The volume average particle diameter or mass average particle diameter of such specific organic particles is preferably 0.01 to 20 μm, among which 0.02 to 2.0 μm is more preferable, and 0.05 to 1.0 μm is more preferable. preferable. Within this range, good resolution and stability over time can be obtained.
[0031]
In the present invention, the specific organic particles preferably have a core-shell structure.
The specific organic particles of the core-shell structure used here are hydrophilic around the core (core part) of a thermoplastic polymer hydrophobic resin obtained by emulsification (including phase inversion emulsification method) or dispersion polymerization method. Core-shell type composite particles (core-shell type particles) in which a polymer polymerization layer (shell part) is formed. The core-shell type composite particles are hydrophilic to the dispersion of core particles (seed) obtained by emulsion polymerization (including phase inversion emulsification) or dispersion polymerization of a hydrophobic monomer that is softened or melted by the action of heat. It is a heterophasic structure particle obtained by adding a hydrophilic monomer and polymerizing a hydrophilic monomer on the surface of the core particle to form a hydrophilic surface layer.
[0032]
The polymer constituting the core portion is at least selected from the group consisting of acrylic polymers, epoxy polymers, styrene polymers, urethane polymers, phenol polymers, vinyl ester polymers, and derivatives thereof. One lipophilic resin. Specifically, it is preferably selected from the above-mentioned polymerizable monomers (A) to (J) and polymers composed of those mentioned as polymerizable unsaturated group-containing oligomers.
[0033]
The hydrophilic polymer that forms the shell portion is a polymer having at least one hydrophilic group selected from a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a hydroxyl group, an amide group, a sulfonamide group, and an amino group. Such a polymer is preferably selected from a copolymer of these monomers having a hydrophilic group and the above-mentioned polymerizable monomers (A) to (J) or a polymerizable unsaturated group-containing oligomer. It is.
[0034]
Specific examples of the specific organic particles having a core-shell structure used in the present invention include epoxy resins, for example, various epoxy compounds as described in JP-A Nos. 5-9431 and 2-42119. .
[0035]
The volume average particle diameter or mass average particle diameter of the specific organic particles having a core-shell structure is preferably 0.01 to 20 μm, more preferably 0.02 to 2.0 μm, and even more preferably 0.05 to 1.0 μm. preferable. Within this range, good resolution and stability over time can be obtained.
[0036]
In order for the specific organic particles in the present invention to dissolve or disperse more easily in the alkaline developer, the acid value of the polymer constituting the specific organic particles is 0.1 to 10 meq / g with respect to KOH. The acid group is preferably 0.5 to 8 meq / g, more preferably 0.8 to 5 meq / g.
[0037]
These specific organic particles may be hollow particles. These are commercially available from JSR and Nippon Zeon.
Moreover, as a dispersion medium for dispersing the specific organic particles, for example, pure water, methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, and dimethylacetamide can be used.
The concentration of the specific organic particles (dispersoid) in the dispersion is preferably 0.1 to 70% by mass, more preferably 0.3 to 60% by mass, and 0.5 to 50%. More preferably, it is mass%.
[0038]
As the particularly preferable specific organic particles in the present invention, it is preferable to use a modified styrene-acrylic copolymer having a Tg of 300 ° C. or higher by three-dimensional crosslinking using divinylbenzene.
[0039]
[Inorganic particles]
The inorganic particles used in the present invention are not particularly limited, but preferred examples include silica sol, alumina sol, magnesium oxide, magnesium carbonate, calcium alginate, titanium oxide, zirconia oxide, and mixtures thereof.
[0040]
Silica sol has many hydroxyl groups on the surface, and the inside constitutes a siloxane bond (—Si—O—Si). Silica ultrafine particles having a particle diameter of 1 to 100 nm are present in a dispersed state in water or a polar solvent due to the surface hydroxyl groups, and are also referred to as colloidal silica. Specifically, it is described in Toshiro Kaga and Hayashi Hayao “Applied Technology of High-Purity Silica”, Volume 3, CMC Co. (1991).
[0041]
Alumina sol is an alumina hydrate (boehmite) having a colloidal size of 5 to 200 nm, and an anion in water (for example, a halogen atom ion such as fluorine ion and chlorine ion, a carboxylate anion such as acetate ion). Etc.) as a stabilizer.
[0042]
Magnesium oxide, magnesium carbonate, calcium alginate, titanium oxide, and zirconia are fine particles of 10 to 400 nm, and are produced by various methods such as a gas phase method, a liquid phase method, and a solid phase method. Latest Trends in Inorganic Fine Particle / Ultrafine Particle Technology and Applications ”, Toray Research Center (1994). In particular, surface modification and composite technology have been established for titanium oxide. Ishihara Sangyo, TAYCA Corp. Easily available from These fine particles are excellent in surface hydrophilicity, and further have a porous surface shape, and thus have a feature of excellent dispersibility in water.
[0043]
The inorganic particles preferably have a volume average particle size or mass average particle size of 10 to 50 nm, but more preferably have a volume average particle size or mass average particle size of 10 to 40 nm. Any of these inorganic particles can be easily obtained as a commercial product.
When the particle size of the inorganic particles is within the above range, other metal fine particles and a photothermal conversion agent described later are stably dispersed, the film strength of the image recording layer is sufficiently maintained, and the alkali solubility during development is extremely high. It produces the effect of becoming an excellent product.
The shape of the inorganic particles is preferably a pearl necklace-like or rod-like inorganic particle group. For example, a spherical colloidal silica having a volume average particle diameter or a mass average particle diameter of 10 to 50 nm has a length of 50 to 400 nm. A continuous shape is different from a spherical one in that it is excellent in immobilization and resistant to shearing scratches.
[0044]
As a dispersion medium for dispersing such inorganic particles, for example, pure water, methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, and dimethylacetamide can be used.
Moreover, it is preferable that the density | concentration of the inorganic particle (dispersoid) in this dispersion liquid is 0.1-50 mass%, and it is more preferable that it is 0.5-30 mass%.
[0045]
The specific organic particles and the inorganic particles are used as a dispersion liquid, but may be used alone or in combination.
As described above, since the overcoat layer in the present invention uses organic particles having a high glass transition temperature Tg or originally uses inorganic particles having high heat resistance, even if the exposed portion (image portion) is heated. Substantially no change in shape or alkali solubility is observed compared to before exposure. As a result, the overcoat layer is excellent in thermal stability without destabilizing the sensitivity.
[0046]
In the present invention, the specific organic particles and the inorganic particles have surface hydrophilicity, so that an overcoat layer can be formed by themselves, but from the viewpoint of film formation, in the development processing step with an alkaline developer. It is preferable to use an organic or inorganic polymer compound that is easily removed by dissolving or dispersing in an alkaline aqueous solution as a binder.
Examples of the organic polymer compound used as the binder include the above-described polymerizable monomers (A) to (J) and a polymerizable unsaturated group-containing oligomer into which an acid group has been introduced (copolymer). ) Polymer compounds that constitute the specific organic particles in the present invention, such as polymers. Further, this (co) polymer may be treated so as to be self-dispersing particles and added to the above-mentioned dispersion liquid of specific organic particles or inorganic particles. At this time, the polymer compound and self-dispersing particles used as the binder are not those having a high glass transition point as in the above-mentioned specific organic particles, but those that are more easily dissolved or dispersed in an alkaline aqueous solution are selected. It is preferable. Other examples of the binder include an alkaline aqueous solution-soluble resin having a phenolic hydroxyl group, which will be described later, and other alkali-soluble polymer compounds.
[0047]
Examples of the inorganic polymer compound used as the binder include sol-gel conversion binder resins described below. In the system capable of sol-gel conversion preferably used in the present invention, the bonds coming out of the polyvalent element form a network structure through oxygen atoms, and the polyvalent element also has an unbonded alkoxy group. , A polymer having a resinous structure in which these are mixed, and is in a sol state when there are many alkoxy groups and hydroxyl groups, and as the dehydration condensation bonding proceeds, the network-like resin structure becomes stronger It becomes.
Further, in addition to the property of changing the hydrophilicity of the resin structure, it also has a function of modifying the surface of the solid fine particles by bonding a part of the hydroxyl groups to the solid fine particles to change the hydrophilicity.
[0048]
Examples of the polyvalent binding element of the compound having a hydroxyl group or an alkoxy group for performing sol-gel conversion include aluminum, silicon, titanium, and zirconium, and any of these can be preferably used in the present invention. Particularly preferably used is a system containing a silane compound having at least one silanol group capable of sol-gel conversion.
A film formed by sol-gel conversion is particularly preferable for forming an overcoat layer using the inorganic polymer compound in the present invention as a binder. The preparation of the organic-inorganic composite sol liquid (hydrophilic coating liquid composition) for forming the overcoat layer according to the present invention utilizes a sol-gel method. Regarding the sol-gel method, Sakuo Sakuo, “Science of Sol-Gel Method”, Agne Jofusha (published) (1988), Satoshi Hirashima, “Technology Center for Functional Thin Films Using the Latest Sol-Gel Method” General Technology Center (Published) (1992) and the like are described in detail, and the methods described therein can be applied to the present invention.
[0049]
[Photothermal conversion agent]
In the present invention, it is preferable to add a photothermal conversion agent to this overcoat layer from the viewpoint of recording sensitivity.
The photothermal conversion agent added to the overcoat layer together with the specific organic particles and inorganic particles may be any substance that absorbs light having a wavelength of 700 nm or more, and various known pigments and dyes are used as infrared absorbers. be able to.
Examples of pigments include commercially available pigment and color index (CI) manuals, “Latest Pigment Handbook” (edited by the Japan Pigment Technology Association, published in 1977), “Latest Pigment Applied Technology” (published by CMC, published in 1986), “Printing” The pigments described in "Ink Technology" (CMC Publishing, 1984) can be used.
[0050]
Examples of the pigment include black pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bonded pigments. 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.
[0051]
These pigments may be used without surface treatment or may be used after surface treatment. Surface treatment methods include surface coating with a hydrophilic resin or lipophilic resin, a method of attaching a surfactant, a reactive substance (eg, silica sol, alumina sol, silane coupling agent, epoxy compound, isocyanate compound, etc.) A method of bonding to the pigment surface is conceivable. 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. Among these pigments, those that absorb infrared rays or near infrared rays are particularly preferable because they are suitable for use in lasers that emit infrared rays or near infrared rays.
[0052]
As such a pigment that absorbs infrared rays or near infrared rays, carbon black, carbon black coated with a hydrophilic resin, or carbon black modified with silica sol is preferably used. Among these, carbon black whose surface is coated with a hydrophilic resin or silica sol is useful as it is easily dispersible with a water-soluble resin and does not impair the hydrophilicity.
[0053]
The particle diameter of the pigment is preferably in the range of 0.01 μm to 1 μm, and more preferably in the range of 0.01 μm to 0.5 μm. 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).
[0054]
As the dye, commercially available dyes and known dyes described in the literature (for example, “Dye Handbook” edited by Organic Synthetic Chemical Society, published in 1970) can be used. Specific examples include azo dyes, metal complex azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, and cyanine dyes. Among these dyes, those that absorb infrared rays or near infrared rays are particularly preferable because they are suitable for use in lasers that emit infrared rays or near infrared rays.
[0055]
Examples of the dye that absorbs infrared rays or near infrared rays include cyanine dyes described in JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, and the like. No. 173696, JP-A-58-181690, JP-A-58-194595, etc., methine dyes, 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, etc., squarylium dyes described in JP-A-58-112792, etc., UK A cyanine dye described in Japanese Patent No. 434,875, a dye described in US Pat. No. 4,756,993, a cyanine dye described in US Pat. No. 4,973,572, It can be mentioned dyes described in JP A No. 10-268512.
[0056]
Further, near-infrared absorption sensitizers described in US Pat. No. 5,156,938 are also preferably used as dyes, and substituted arylbenzo (thio) pyrylium described in US Pat. No. 3,881,924. Salt, trimethine thiapyrylium salt described in JP-A-57-142645 (US Pat. No. 4,327,169), JP-A-58-181051, 58-220143, 59-41363, 59 -84248, 59-84249, 59-146063, 59-146061, pyrylium compounds described in JP-A-59-216146, cyanine dyes described in U.S. Pat. No. 4,283,475 Pentamethine thiopyrylium salts described in No. 5 and pyrylium compounds disclosed in Japanese Patent Publication Nos. 5-13514 and 5-19702 Mentioned as preferred as commercial products, Eporin Co. EpolightIII-178, EpolightIII-130, EpolightIII-125 are preferably used.
Among these dyes, particularly preferred specific examples are listed below by structural formulas.
[0057]
[Chemical 1]

[0058]
[Chemical 2]

[0059]
The pigment or dye is 1 to 70% by weight, preferably 2 to 50% by weight in the total solid content of the overcoat layer, particularly preferably 2 to 30% by weight in the case of a dye, and particularly preferably 20 to 50% in the case of a pigment. It is a percentage by weight. When the amount of the pigment or dye added is in the above preferred range, suitable recording sensitivity and uniformity and durability of the overcoat layer can be ensured.
[0060]
[Surfactant]
In the present invention, a surfactant is preferably added to the overcoat layer in order to expand the stability to printing conditions. As the surfactant, in addition to nonionic and anionic surfactants, cationic surfactants, fluorine-containing surfactants, and JP-A-59-121044 as described in JP-A-2-195356. And amphoteric surfactants described in JP-A-4-13149 can be added.
[0061]
Specific examples of preferred nonionic surfactants added to the overcoat layer include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, Polyoxyethylene alkylaryl ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene / polyoxypropylene block copolymers, and fatty acids having 5 to 24 carbon atoms in the hydroxyl group at the terminal of the polyoxyethylene / polyoxypropylene block copolymer Compound polyoxyalkylene alkyl ethers having an ether group bonded to the same group, and compound polyoxyalkylene alkyl groups having an alkyl-substituted aryl group bonded to an ether group. Ruethers, sorbitan monolaurate, sorbitan monostearate, sorbitan tristearate, sorbitan monopalmitate, sorbitan fatty acid esters such as sorbitan monooleate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan mono And polyoxyethylene sorbitan fatty acid esters such as palmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, and polyoxyethylene sorbitan trioleate.
[0062]
Specific examples of amphoteric surfactants include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine, and N-tetradecyl-N, N- Examples include betaine type (for example, trade name Amorgen K, manufactured by Dai-ichi Kogyo Co., Ltd.).
[0063]
Specific examples of the anionic activator include alkyl sulfonic acids, aryl sulfonic acids, aliphatic carboxylic acids, alkyl naphthalene sulfonic acids, alkyl naphthalene sulfonic acid or a condensed type of naphthalene sulfonic acid and formaldehyde, and those having 9 to 26 carbon atoms. Examples thereof include aliphatic sulfonic acids, alkylbenzene sulfonic acids, lauryl polyoxyethylene sulfuric acid, cetyl polyoxyethylene sulfonic acid, polyoxyethylene-containing sulfuric acid such as oleyl polyoxyethylene phosphonic acid, and polyoxyethylene-containing phosphoric acid.
[0064]
Specific examples of the cationic activator include laurylamine acetate, lauryltrimethylammonium chloride, distearyldimethylammonium chloride, alkylbenzyldimethylammonium chloride and the like.
[0065]
In the overcoat layer, a fluorine-based surfactant may be used in the range of the preferable addition amount of the surfactant described later in some cases. Specifically, a surfactant having a perfluoroalkyl group is preferred, and an anionic fluorosurfactant having any one of carboxylic acid, sulfonic acid, sulfate ester and phosphate ester, or an aliphatic amine, Cationic fluorinated surfactants such as quaternary ammonium salts, betaine fluorinated amphoteric surfactants, or fluorine-based compounds such as aliphatic esters of polyoxy compounds, polyalkylene oxide condensed types, and polyethyleneimine condensed types Nonionic surfactants and the like can be mentioned.
The proportion of the surfactant in the total solid of the image forming layer is preferably 0.01 to 15% by mass, more preferably 0.05 to 5% by mass.
[0066]
The thickness of the overcoat layer in the lithographic printing plate precursor according to the invention is preferably from 0.01 μm to 4.0 μm, more preferably from 0.05 μm to 2.0 μm. If the layer is too thick, it may cause a decrease in sensitivity, or may promote performance deterioration of the developer due to an overcoat layer component that is dissolved and removed, and if it is too thin, the film property is impaired. It may be difficult to obtain the preferable effect.
[0067]
<Image recording layer>
As described above, the image recording layer in the invention contains a substance that absorbs light and generates heat, and an alkaline aqueous solution-soluble resin having a phenolic hydroxyl group.
[Alkaline aqueous solution-soluble resin having phenolic hydroxyl group]
Examples of the aqueous alkali-soluble resin having a phenolic hydroxyl group used in the present invention (hereinafter referred to as “resin having a phenolic hydroxyl group”) include phenol formaldehyde resin, m-cresol formaldehyde resin, p-cresol formaldehyde resin, m. Examples thereof include novolak resins such as − / p-mixed cresol formaldehyde resin and phenol / cresol (which may be m-, p-, or m− / p-mixed) mixed formaldehyde resin.
[0068]
These resins having a phenolic hydroxyl group preferably have a weight average molecular weight of 500 to 20,000 and a number average molecular weight of 200 to 10,000. Furthermore, as described in US Pat. No. 4,123,279, a condensate of phenol and formaldehyde having an alkyl group having 3 to 8 carbon atoms as a substituent, such as t-butylphenol formaldehyde resin and octylphenol formaldehyde resin. May be used in combination. Such resins having a phenolic hydroxyl group may be used alone or in combination of two or more.
[0069]
In the present invention, the resin having the phenolic hydroxyl group and a copolymer (hereinafter referred to as “specific copolymer”) containing at least one of the following (a) to (c) as a copolymerization component at 10 mol% or more. )) In combination.
[0070]
(A) Monomer having a sulfonamide group in which at least one hydrogen atom is bonded to a nitrogen atom in one molecule
(B) Monomer having an active imino group represented by the following formula in one molecule
[0071]
[Chemical 3]

[0072]
(C) Acrylamide, methacrylamide, acrylic ester, methacrylic ester or hydroxystyrene each having a phenolic hydroxyl group
[0073]
The specific copolymer in the present invention is required to contain 10 mol% or more as a copolymerization component of at least one of the above (a) to (c), and more preferably contains 20 mol% or more. . When the amount is less than 10 mol%, the interaction with the resin having a phenolic hydroxyl group becomes insufficient and the development latitude is lowered. Moreover, the copolymerization component other than said (a) to (c) may be included.
[0074]
The monomer corresponding to (a) is a monomer composed of a low molecular compound having one or more polymerizable unsaturated bonds and a sulfonamide group in which at least one hydrogen atom is bonded on a nitrogen atom in one molecule. It is. Among these, a low molecular compound having an acryloyl group, an allyl group, or a vinyloxy group, and a substituted or monosubstituted aminosulfonyl group or a substituted sulfonylimino group is preferable.
Examples of such compounds include compounds represented by the following general formulas (I) to (V).
[0075]
[Formula 4]

[0076]
Where X ¹ , X ² Are —O— or —NR, respectively. ¹⁰ -Is shown. R ⁴ , R ⁷ Are each a hydrogen atom or —CH ₃ Represents. R ⁵ , R ⁸ , R ¹² , R ¹⁵ , R ¹⁹ Each represents an alkylene group having 1 to 12 carbon atoms, a cycloalkylene group, an arylene group or an aralkylene group which may have a substituent. R ⁶ , R ¹⁰ , R ¹⁶ Represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group or an aralkyl group, each optionally having a substituent. R ⁹ , R ²⁰ Represents an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, an aryl group, or an aralkyl group, each of which may have a substituent. R ¹¹ , R ¹³ , R ¹⁷ Is a hydrogen atom or -CH ₃ Represents. R ¹⁴ , R ¹⁸ Each represents a C1-C12 alkylene group, cycloalkylene group, arylene group or aralkylene group which may have a single bond or a substituent. Y ¹ , Y ² Each represents a single bond or —CO—.
[0077]
Specifically, m-aminosulfonylphenyl methacrylate, N- (p-aminosulfonylphenyl) methacrylamide, N- (p-aminosulfonylphenyl) acrylamide and the like can be preferably used.
[0078]
The monomer corresponding to (b) is a monomer composed of a low molecular compound having one or more active imino groups represented by the above formula and one or more polymerizable unsaturated bonds in one molecule. As such a compound, specifically, N- (p-toluenesulfonyl) methacrylimide, N- (p-toluenesulfonyl) acrylimide and the like can be preferably used.
[0079]
The monomer corresponding to (c) is a monomer composed of acrylamide, methacrylamide, acrylate ester, methacrylate ester or hydroxystyrene each having a phenolic hydroxyl group. Specific examples of such compounds include N- (4-hydroxyphenyl) acrylamide, N- (4-hydroxyphenyl) methacrylamide, o-hydroxyphenyl acrylate, m-hydroxyphenyl acrylate, and p-hydroxyphenyl acrylate. O-hydroxyphenyl methacrylate, m-hydroxyphenyl methacrylate, p-hydroxyphenyl methacrylate, o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene and the like can be suitably used.
[0080]
As other copolymerization components, for example, monomers listed in the following (1) to (12) can be used.
(1) Acrylic acid esters and methacrylic acid esters having an aliphatic hydroxyl group such as 2-hydroxyethyl acrylate or 2-hydroxyethyl methacrylate.
(2) Methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, octyl acrylate, benzyl acrylate, 2-chloroethyl acrylate, glycidyl acrylate, N-dimethylaminoethyl Alkyl acrylates such as acrylates;
(3) Methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, 2-chloroethyl methacrylate, glycidyl methacrylate, N-dimethylaminoethyl Alkyl methacrylate such as methacrylate.
(4) Acrylamide, methacrylamide, N-methylol acrylamide, N-ethyl acrylamide, N-hexyl methacrylamide, N-cyclohexyl acrylamide, N-hydroxyethyl acrylamide, N-phenyl acrylamide, N-nitrophenyl acrylamide, N-ethyl- Acrylamide or methacrylamide such as N-phenylacrylamide.
(5) Vinyl ethers such as ethyl vinyl ether, 2-chloroethyl vinyl ether, hydroxyethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, octyl vinyl ether, and phenyl vinyl ether.
[0081]
(6) Vinyl esters such as vinyl acetate, vinyl chloroacetate, vinyl butyrate and vinyl benzoate.
(7) Styrenes such as styrene, α-methylstyrene, methylstyrene, and chloromethylstyrene.
(8) Vinyl ketones such as methyl vinyl ketone, ethyl vinyl ketone, propyl vinyl ketone, and phenyl vinyl ketone.
(9) Olefins such as ethylene, propylene, isobutylene, butadiene, and isoprene.
(10) N-vinylpyrrolidone, N-vinylcarbazole, 4-vinylpyridine, acrylonitrile, methacrylonitrile and the like.
(11) Unsaturated imides such as maleimide, N-acryloylacrylamide, N-acetylmethacrylamide, N-propionylmethacrylamide, N- (p-chlorobenzoyl) methacrylamide.
(12) Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic anhydride and itaconic acid.
[0082]
The specific copolymer in the present invention preferably has a weight average molecular weight of 2000 or more and a number average molecular weight of 1000 or more. More preferably, the weight average molecular weight is 5000 to 300000, the number average molecular weight is 2000 to 250,000, and the dispersity (weight average molecular weight / number average molecular weight) is 1.1 to 10.
Such specific copolymers may be used alone or in combination of two or more.
[0083]
The blending weight ratio of the resin having a phenolic hydroxyl group and the specific copolymer is preferably in the range of 50:50 to 5:95, and more preferably in the range of 40:60 to 10:90. . If the amount of the resin having a phenolic hydroxyl group is increased, the sea-island structure is reversed and it is difficult to improve the solvent resistance. On the other hand, if the amount of the copolymer is increased, the surface layer made of the resin having a phenolic hydroxyl group becomes too thin, and the development latitude is insufficiently improved.
[0084]
These alkali-soluble polymer compounds composed of a resin having a phenolic hydroxyl group and a specific copolymer may be used alone or in combination of two or more, respectively. It is used in an addition amount of 99% by weight, preferably 40 to 95% by weight, particularly preferably 50 to 90% by weight. If the addition amount of the alkali-soluble polymer compound is less than 30% by weight, the durability of the image recording layer is deteriorated, and if it exceeds 99% by weight, it is not preferable in terms of both sensitivity and durability.
Further, the image forming layer containing an alkali-soluble polymer compound composed of a resin having a phenolic hydroxyl group and a specific copolymer may have a layer structure divided into two layers, or divided into more layers. A multilayer structure may be used.
[0085]
[Material that absorbs light and generates heat]
As the substance that absorbs light and generates heat in the present invention, the same pigments and dyes as those of the photothermal conversion agent listed as the constituent component of the overcoat layer can be used.
As a substance that absorbs light contained in the image forming layer and generates heat, a pigment or dye that absorbs infrared light or near infrared light is used in a laser that emits infrared light or near infrared light. It is particularly preferable because it is suitable for use.
[0086]
These pigments or dyes are 0.01 to 50% by weight, preferably 0.1 to 10% by weight, particularly preferably 0.5 to 10% by weight, and pigments, based on the total solid content of the printing plate material. Particularly preferably, it can be added to the printing plate material at a ratio of 3.1 to 10% by weight. When the added amount of the pigment or dye is less than 0.01% by weight, the sensitivity is lowered, and when it exceeds 50% by weight, the uniformity of the photosensitive layer is lost and the durability of the image recording layer is deteriorated. These dyes or pigments may be added to the same layer as other components, or another layer may be provided and added thereto. The dye or pigment and the binder resin are preferably the same layer, but may be different layers.
[0087]
[Other ingredients]
In forming the image recording layer according to the present invention, various additives can be added as necessary in addition to the above-described essential components as long as the effects of the present invention are not impaired.
For example, a substance that is thermally decomposable, such as an onium salt, an o-quinonediazide compound, an aromatic sulfone compound, and an aromatic sulfonic acid ester compound, and that substantially reduces the solubility of the alkaline water-soluble polymer compound without being decomposed. Use in combination is preferable in terms of improving the dissolution inhibition of the image area in the developer. Examples of onium salts include diazonium salts, ammonium salts, phosphonium salts, iodonium salts, sulfonium salts, selenonium salts, and arsonium salts.
[0088]
Preferred examples of the onium salt used in the present invention include S.P. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Bal et al, Polymer, 21, 423 (1980), diazonium salts described in JP-A-5-158230, U.S. Pat. Nos. 4,069,055, 4,069,056, and JP-A-3-140140. Ammonium salts described in the specification of C. Necker et al, Macromolecules, 17, 2468 (1984), C.I. S. Wenetal, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), U.S. Pat. Nos. 4,069,055 and 4,069,056; V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), Chem. & Eng. News, Nov. 28, p31 (1988), European Patent No. 104,143, U.S. Pat. Nos. 339,049, 410,201, JP-A-2-150848, JP-A-2-296514, . V. Crivello et al, Polymer J. et al. 17, 73 (1985), J. Am. V. Crivello et al. J. et al. Org. Chem. 43, 3055 (1978); R. Watt et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 22, 1789 (1984), J. Am. V. Crivello et al, Polymer Bull. 14, 279 (1985), J. Am. V. Crivello et al, Macromolecules, 14 (5), 1141 (1981), J. MoI. V. Crivello et al, J.A. Polymer Sci. , Polymer Chem. Ed. 17, 2877 (1979), European Patents 370,693, 233,567, 297,443, 297,442, U.S. Pat. Nos. 4,933,377, 3,902,114 Nos. 410, 201, 339, 049, 4,760, 013, 4, 734, 444, 2, 833, 827, German Patent No. 2,904, 626, Sulfonium salts described in JP-A-3,604,580 and JP-A-3,604,581, V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al, J.A. Polymer Sci. , Polymer Chem. Ed. , 17, 1047 (1979), a selenonium salt described in C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988).
Of the onium salts, diazonium salts are particularly preferred. Particularly suitable diazonium salts include those described in JP-A-5-158230.
[0089]
The counter ion of the onium salt includes tetrafluoroboric acid, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, 2,5-dimethylbenzenesulfonic acid, 2,4,6-trimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 1-naphthol-5-sulfone Examples include acid, 2-methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, and paratoluenesulfonic acid. Of these, particularly preferred are alkyl aromatic sulfonic acids such as hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid and 2,5-dimethylbenzenesulfonic acid.
[0090]
Suitable quinonediazides include o-quinonediazide compounds. The o-quinonediazide compound used in the present invention is a compound having at least one o-quinonediazide group, which increases alkali solubility by thermal decomposition, and compounds having various structures can be used. That is, o-quinonediazide helps the solubility of the sensitive material system by both the effect of losing the ability to suppress the dissolution of the binder due to thermal decomposition and the change of o-quinonediazide itself into an alkali-soluble substance. Examples of the o-quinonediazide compound used in the present invention include J. Although the compounds described in pages 339 to 352 of “Light-Sensitive Systems” by John Coser (John Wiley & Sons. Inc.) can be used, they are particularly reacted with various aromatic polyhydroxy compounds or aromatic amino compounds. -Sulfonic acid esters or sulfonic acid amides of quinonediazides are preferred. Further, benzoquinone (1,2) -diazidosulfonic acid chloride or naphthoquinone- (1,2) -diazide-5-sulfonic acid chloride and pyrogallol-acetone resin as described in JP-B-43-28403 Esters of benzoquinone- (1,2) -diazide sulfonic acid chloride or naphthoquinone- (1,2) -diazide- described in US Pat. Nos. 3,046,120 and 3,188,210 Esters of 5-sulfonic acid chloride and phenol-formaldehyde resin are also preferably used.
[0091]
Further, esters of naphthoquinone- (1,2) -diazide-4-sulfonic acid chloride with phenol formaldehyde resin or cresol-formaldehyde resin, naphthoquinone- (1,2) -diazido-4-sulfonic acid chloride and pyrogallol-acetone resin Similarly, the esters are also preferably used. Other useful o-quinonediazide compounds are reported and known in numerous patents. For example, JP-A-47-5303, JP-A-48-63802, JP-A-48-63803, JP-A-48-96575, JP-A-49-38701, JP-A-48-13354, JP-B-41-11222, JP-B-45-9610, JP-B-49-174781, U.S. Pat. Nos. 2,797,213, 3,454,400, 3,544,323, 3,573,917, 3,674,495, 3,785,825, British Patents 1,227,602, 1,251,345, 1,267 No. 1,005, No. 1,329,888, No. 1,330,932, German Patent No. 854,890, and the like.
[0092]
The addition amount of the o-quinonediazide compound is preferably in the range of 1 to 50% by mass, more preferably 5 to 30% by mass, and particularly preferably 10 to 30% by mass with respect to the total solid content of the printing plate material. These compounds can be used alone, but may be used as a mixture of several kinds.
[0093]
For the purpose of further improving the sensitivity, cyclic acid anhydrides, phenols, and organic acids can be used in combination. Examples of cyclic acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3,6-endooxy-tetrahydrophthalic anhydride, and tetrachloroanhydride described in US Pat. No. 4,115,128. Phthalic acid, maleic anhydride, chloromaleic anhydride, α-phenylmaleic anhydride, succinic anhydride, pyromellitic anhydride and the like can be used. As phenols, bisphenol A, p-nitrophenol, p-ethoxyphenol, 2,4,4′-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4-hydroxybenzophenone, 4,4 ′, 4 '' -Trihydroxytriphenylmethane, 4,4 ′, 3 ″, 4 ″ -tetrahydroxy-3,5,3 ′, 5′-tetramethyltriphenylmethane and the like. Furthermore, examples of organic acids include sulfonic acids, sulfinic acids, alkyl sulfates, phosphonic acids, phosphate esters, and carboxylic acids described in JP-A-60-88942 and JP-A-2-96755. Specifically, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethyl sulfate, phenylphosphonic acid, phenylphosphinic acid, phenyl phosphate, diphenyl phosphate, benzoic acid, isophthalic acid, Examples include adipic acid, p-toluic acid, 3,4-dimethoxybenzoic acid, phthalic acid, terephthalic acid, 4-cyclohexene-1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid, ascorbic acid and the like. .
The proportion of the cyclic acid anhydride, phenols and organic acids in the printing plate material is preferably 0.05 to 20% by mass, more preferably 0.1 to 15% by mass, particularly preferably 0.1 to 0.1% by mass. 10% by mass.
[0094]
Further, in the image recording layer coating solution according to the present invention, in order to broaden the stability of the processing with respect to the developing conditions, the non-printing methods described in JP-A-62-251740 and JP-A-3-208514 are not used. Ionic surfactants, amphoteric surfactants as described in JP-A-59-121044, JP-A-4-13149, siloxane compounds as described in EP950517, JP-A-11- A fluorine-containing monomer copolymer as described in Japanese Patent No. 288093 can be added.
Specific examples of the nonionic surfactant include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether and the like. Specific examples of amphoteric activators include alkyldi (aminoethyl) glycine, alkylpolyaminoethylglycine hydrochloride, 2-alkyl-N-carboxyethyl-N-hydroxyethylimidazolinium betaine and N-tetradecyl-N, N-betaine. Type (for example, trade name “Amorgen K” manufactured by Daiichi Kogyo Co., Ltd.).
The siloxane compound is preferably a block copolymer of dimethylsiloxane and polyalkylene oxide. Specific examples include DBE-224, DBE-621, DBE-712, DBP-732, DBP-534, manufactured by Chisso Corporation. And polyalkylene oxide-modified silicones such as Tego Glide 100 manufactured by Tego, Germany.
The proportion of the nonionic surfactant and the amphoteric surfactant in the printing plate material is preferably 0.05 to 15% by mass, more preferably 0.1 to 5% by mass.
[0095]
In the image recording layer of the present invention, a print-out agent for obtaining a visible image immediately after heating by exposure, or a dye or pigment as an image colorant can be added.
Typical examples of the printing-out agent include a combination of a compound that releases an acid by heating by exposure (photoacid releasing agent) and an organic dye that can form a salt. Specifically, combinations of o-naphthoquinonediazide-4-sulfonic acid halides and salt-forming organic dyes described in JP-A-50-36209 and JP-A-53-8128, 36223, 54-74728, 60-3626, 61-143748, 61-151644 and 63-58440, and trihalomethyl compounds and salt-forming organic dyes Can be mentioned. Such trihalomethyl compounds include oxazole-based compounds and triazine-based compounds, both of which have excellent temporal stability and give clear printout images.
[0096]
As the image colorant, other dyes can be used in addition to the above-mentioned salt-forming organic dyes. Examples of suitable dyes including salt-forming organic dyes include oil-soluble dyes and basic dyes. 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 (oriental chemical industry) Manufactured by Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), and the like. The dyes described in JP-A-62-293247 are particularly preferred. These dyes can be added to the printing plate material in a proportion of 0.01 to 10% by mass, preferably 0.1 to 3% by mass, based on the total solid content of the printing plate material. Furthermore, a plasticizer is added to the image recording layer of the present invention as necessary in order to impart flexibility of the coating film. For example, butylphthalyl, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate, acrylic acid or methacrylic acid These oligomers and polymers are used.
[0097]
<Support>
As the support used in the lithographic printing plate precursor according to the invention, a dimensionally stable plate-like material is used. Paper, paper laminated with lipophilic plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, nickel, stainless steel plate, etc.), plastic film (eg, cellulose diacetate, three Cellulose acetate, 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 metals are laminated or deposited .
Among these, polyethylene terephthalate film, polycarbonate film, aluminum or steel plate, or aluminum or steel plate on which an oleophilic plastic film is laminated is preferable.
[0098]
As an aluminum plate preferably used in the present invention, an aluminum plate made of a publicly known material can be appropriately used.
Prior to using the aluminum plate, (a) improvement of the hydrophilicity of the surface which becomes a non-image part after development, (b) improvement of water retention during printing, (c) improvement of surface wear resistance and (d) It is preferable to perform a surface treatment in order to ensure adhesiveness with what is applied thereon. For surface treatment, various techniques such as roughening, anodizing treatment, silicate treatment, and undercoating are known, and the aluminum support used in the present invention has the known and used aluminum plate surface treatment technology. It can be used as appropriate.
[0099]
<Method for producing planographic printing plate precursor>
The lithographic printing plate precursor according to the invention is produced by forming the image recording layer on the above-mentioned support by usually dissolving each of the above components in a solvent and forming the overcoat layer thereon. The
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-butyrolactone, and toluene. It is not limited. These solvents are used alone or in combination.
The concentration of the above components (total solid content including additives) in the solvent is preferably 1 to 50% by weight.
The coating amount (solid content) on the support obtained after coating and drying varies depending on the use, but generally speaking, 0.5 to 5.0 g / m for photosensitive printing plates. ² Is preferred. As the coating amount decreases, the apparent sensitivity increases, but the film properties of the photosensitive film deteriorate.
Various methods can be used as the coating method, and examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating.
[0100]
<Image formation>
The heat-sensitive lithographic printing plate precursor of the present invention is imaged by heat. Specifically, direct image-like recording using a thermal recording head, scanning exposure using an infrared laser, high-illuminance flash exposure such as a xenon discharge lamp, infrared lamp exposure, and the like are used. Exposure by a solid high-power infrared laser such as a laser or a YAG laser is suitable.
[0101]
An alkali-soluble resin having a phenolic hydroxyl group is prevented from dissolving by intermolecular interaction to form an alkali-insoluble layer, which is converted to alkali-soluble by photolysis reaction by image-like energy irradiation or destruction of intermolecular interaction by heat. In the positive type printing plate having a mechanism for developing an image to form an image, an alkaline aqueous solution is usually used as the developer. In principle, the same printing plate precursor of the present invention is also developed with an alkaline aqueous solution.
[0102]
This alkaline developer contains an alkali agent as a main component, and in addition, a surfactant, a hard water softener, an antiseptic, an antifoaming agent, and the like are added as necessary.
Examples of the alkali agent include sodium silicate, potassium, tribasic sodium phosphate, potassium, ammonium, dibasic sodium phosphate, potassium, ammonium, sodium carbonate, potassium, ammonium, sodium bicarbonate. Inorganic alkaline salts such as potassium, ammonium, sodium hydroxide, ammonium, potassium and lithium. In addition, organic alkaline agents such as monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine are also used. These alkali agents are used alone or in combination of two or more.
[0103]
Of these alkali agents, sodium silicate, potassium silicate and the like are particularly preferable. The reason is silicon oxide SiO, which is a component of silicate. ₂ And alkali metal oxide M ₂ This is because the developability can be adjusted to some extent by the ratio and density of O. In addition, almost all positive photosensitive lithographic printing plates require strong alkalis having a pH of around 13 for development, and silicates exhibit a good buffering action in the pH range, and stable development is possible. The lithographic printing plate precursor according to the invention can be developed with an alkaline developer containing the well-known silicate as a main component.
[0104]
In JP-A-8-160631 and JP-A-8-305039, saccharides, sodium hydroxide and sodium carbonate are the main components and silicate is not contained at pH 11.0-13.5 or pH 9.0-13. A range of 5 developers is disclosed. When the developers disclosed in these publications are used, the problems with developers containing silicates, that is, they are stable in the alkaline region but gelled in neutrality, and when evaporated to dryness, hydrofluoric acid It can only be dissolved in strong acids like the above, and it can solve problems such as contamination of the automatic processor due to insoluble matter adhesion, malfunction of the sensor for development replenishment, or obstruction of processing work due to insoluble matter precipitation during processing of development waste liquid. It is stated. The lithographic printing plate precursor according to the invention can be suitably developed even with an alkaline developer containing no silicate.
[0105]
After the development, the lithographic printing plate precursor according to the invention is washed or rinsed and / or gummed, and if necessary, the image area is erased, in the same manner as a conventional lithographic printing plate precursor. The lithographic printing plate thus obtained can be subjected to a printing process.
[0106]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated according to the following examples, the scope of the present invention is not limited to these examples.
[0107]
[Examples 1-7]
[Production of aluminum substrate]
An aluminum plate (material 1050) having a thickness of 0.24 mm was grained on the surface using a nylon brush and 400 mesh Pamiston water suspension, and washed thoroughly with water. This plate was immersed in a 15% aqueous sodium hydroxide solution for etching, and then washed with water. Further neutralize with 1% nitric acid, then use a rectangular alternating current in a 0.7% nitric acid aqueous solution, 160 coulomb / dm ² Electrolytic surface roughening treatment was performed with the amount of electricity at the time of anode. After washing with water, etching was performed by immersing in a 10% aqueous sodium hydroxide solution, followed by washing with water. Next, it was desmutted by immersing it in a 30% aqueous sulfuric acid solution, followed by washing with water. Furthermore, anodization was performed using a direct current in a 20% aqueous sulfuric acid solution, and the oxide film amount was 2.7 g / m. ² It was. Further, after treatment with a 0.5 wt% aqueous solution of sodium silicate at 30 ° C. for 10 seconds, the following undercoat solution was applied, and the coating film was dried at 80 ° C. for 15 seconds to obtain a substrate. The coating amount of the coating after drying is 4.5 mg / m ² Met.
[0108]
(Undercoat liquid)
The following compound ... 0.3g
Methanol ... 100g
1g of water
[0109]
[Chemical formula 5]

[0110]
(Formation of image recording layer)
The following coating solution A for the image recording layer was applied to the obtained support at a coating amount of 1.0 g / m. ² After coating, the Wind Control was set to 7 with a TARFAI PERFECT OVEN PH200 and dried at 140 degrees for 50 seconds to form an image recording layer.
[0111]

[0112]
[Chemical 6]

[0113]
[Formation of overcoat layer]
Thereafter, an overcoat layer coating solution having the following composition was applied to the substrate on which the image recording layer A was coated, with a liquid volume of 7.5 cc / m. ² And dried at 80 ° C. for 2 minutes to a dry weight of 0.1 g / m ² The positive lithographic printing plate precursors 1 to 7 in Examples 1 to 7 having the overcoat layer were prepared.
[0114]
(Overcoat layer coating solution)
・ Polyacrylic acid: 7.04g
(Aldrich, Mw: 1000, 5% aqueous solution)
-Dispersion of specific organic particles or inorganic particles described in Table 1 below 2.00 g
(Dispersoid content 20%)
・ Distilled water ... 17.28g
・ Isopropyl alcohol ・ ・ ・ 2.72g
[0115]
[Example 8]
The following coating solution B for image recording layer was applied to the same support as that used in Examples 1 to 7 with an undercoat layer in an amount of 0.9 g / m. ² The image recording layer B was formed by coating and drying.
[0116]

[0117]
Further, on the image recording layer B, the following coating solution C for image recording layer was applied in an amount of 0.3 g / m ² The image recording layer C was formed by coating and drying.
[0118]
(Coating liquid C for image recording layer)
・ Propylene glycol monomethyl ether ・ ・ ・ 12.87g
・ M, p-cresol novolak ・ ・ ・ 0.21g
(M / p = 6/4 Mw 3,500)
・ Fluorine surfactant: 0.01g
(Megafuck F-176, 20% made by Dainippon Ink)
・ Infrared absorbent (1) with the following structure: 0.02 g
・ Butyl methacrylate / ethyl methacrylate / methacrylic acid ・ 0.02g
(37/37/26 Mw49,000)
[0119]
Thereafter, an overcoat layer coating solution having the same composition as in Examples 1 to 7 was applied on the substrate coated with the image recording layer C and dried to produce a positive planographic printing plate precursor 8 in Example 8. did.
[0120]
[Comparative Examples 1 and 2]
The lithographic printing plate precursor of Comparative Example 1 was obtained by applying no overcoat layer on the surface of the image recording layer A.
Further, a coating liquid in which specific organic particles or inorganic particles are removed from the overcoat layer coating liquid is prepared, and the liquid volume is 7.5 cc / m on the surface of the image recording layer A. ² And dried at 80 ° C. for 2 minutes to a dry weight of 0.1 g / m ² A lithographic printing plate precursor of Comparative Example 2 was formed by forming the overcoat layer.
[0121]
[Comparative Example 8]
In Example 8, the lithographic printing plate precursor of Comparative Example 3 was obtained by applying no overcoat layer to the surface of the image recording layer C.
[0122]
[Evaluation of planographic printing plate precursor]
Each lithographic printing plate precursor produced as described above was attached to a trend setter (plate setter equipped with a 40 W 830 nm semiconductor laser) manufactured by Canada CREO and exposed like an image. Next, development was performed using a PS processor 940H made by Fuji Photo Film. As the developer, DT-1 (1: 8) manufactured by Fuji Photo Film Co., Ltd. was used at 30 ° C. for 12 seconds. As the finisher liquid, FP-2W (1: 1) manufactured by Fuji Photo Film Co., Ltd. was used.
[0123]
(Solvent resistance, printing durability)
Using the developed lithographic printing plate, it was printed on high-quality paper with Komori Printing Machine Sprint. Printing was performed while wiping the plate surface with a cleaner solution (plate cleaner CL2 manufactured by Fuji Photo Film Co., Ltd.) every time 5000 sheets were printed. Here, the final number of printed sheets is the number of images obtained until a so-called plate jump occurs until the image forming layer of the lithographic printing plate undergoes film thickness reduction and ink is not partially consumed. It is evaluated that the greater the number, the better the printing durability.
[0124]
(Stability evaluation over time)
The prepared lithographic printing plate precursor was stored at 45 ° C. and 75% relative humidity under high temperature and high humidity for 3 days. The lithographic printing plate precursor after storage with time was exposed to the plate setter and the minimum amount of energy capable of forming an image was measured. Further, this lithographic printing plate precursor before storage under high temperature and high humidity was also evaluated by measuring the amount of energy and comparing the difference between them, that is, the sensitivity fluctuation before and after forced aging. The smaller the difference between the two values, the better the stability over time.
[0125]
(Evaluation of coating film strength for printing)
The coating film strength was evaluated by scratching by changing the load with a scratch tester having a sapphire needle having a diameter of 1.0 mmφ, and obtaining the maximum load with no scratches on the scratched portion after development.
[0126]
(Glass transition point Tg of organic particles)
The glass transition point Tg of the specific organic particles in the specific organic particle dispersions used in Examples 1 to 4 and Example 8 was measured by the following method.
First, after drying the specific organic particle dispersion used in Examples 1 to 4 and Example 8 and taking out only the solid content, about 10 mg, differential scanning calorimeter (DSC200) and thermal analysis system manufactured by Seiko Instruments Inc. Using (SSC5100), the temperature was raised from 25 ° C. to 230 ° C. at 10 ° C./min, and the amount of heat was measured. As a result, no characteristic peak was observed in any organic particles. Furthermore, when a measurement was performed using a differential thermothermal gravimetric simultaneous measurement meter (TG / DTA) under the same conditions, no characteristic peak was observed here. Therefore, it was found that the glass transition point Tg of the specific organic particles used in this example is 200 ° C. or higher.
[0127]
[Table 1]

[0128]
As is apparent from Table 1, the lithographic printing plate precursor according to the present invention is excellent in film strength and printing durability, suppressed in sensitivity fluctuations at high temperature and high humidity, and excellent in storage stability.
[0129]
【The invention's effect】
According to the present invention, there is provided a lithographic printing plate precursor having excellent solvent resistance and development latitude, and improved storage stability that does not deteriorate printing durability and handling properties even in environments such as scratch resistance and high temperature and high humidity. can do.

Claims (1)

On the support,
An image recording layer containing a substance that absorbs light and generates heat, and an aqueous alkali-soluble compound having a phenolic hydroxyl group;
An overcoat layer containing organic particles having an alkali water-soluble or alkali-liquid dispersibility glass transition point Tg of 200 ° C. or higher, or alkali water-soluble or alkali-liquid dispersible inorganic particles;
A positive-type planographic printing plate precursor characterized by comprising: