JP4303898B2 - Master for lithographic printing plate - Google Patents

Description

【００５４】
【化２】

【００５５】
【化３】

【００５６】
【化４】

【００５７】
本発明に用いられるエチレンオキシド鎖を有する化合物は、単独で使用しても良いし、２種以上を混合して使用しても良い。この化合物の画像形成層への添加量は、画像形成層固形分の０．１〜２０％が好ましく、より好ましくは１〜１０％である。この範囲で良好な機上現像性と耐刷性が得られる。
【００５８】
本発明の画像形成層は、機上現像性の向上や画像形成層の皮膜強度のために親水性樹脂を添加することができる。親水性樹脂としては３次元架橋していないものが機上現像性が良好で好ましい。
【００５９】
親水性樹脂としては、例えばヒドロキシル基、カルボキシル基、ヒドロキシエチル基、ヒドロキシプロピル基、アミノ基、アミノエチル基、アミノプロピル基、カルボキシメチル基等の親水基を有するものが好ましい。
【００６０】
親水性樹脂の具体例として、アラビアゴム、カゼイン、ゼラチン、ソヤガム、澱粉及びその誘導体、ヒドロキシエチルセルロース、ヒドロキシプロピルセルロース、メチルセルロース、カルボキシメチルセルロースおよびその塩及びセルロースアセテート等のセルロース誘導体、アルギン酸及びそのアルカリ金属塩、アルカリ土類金属塩又はアンモニウム塩、水溶性ウレタン樹脂、水溶性ポリエステル樹脂、酢酸ビニル−マレイン酸コポリマー類、スチレン−マレイン酸コポリマー類、ポリアクリル酸類およびそれらの塩、ポリメタクリル酸類およびそれらの塩、ヒドロキシエチルメタクリレートのホモポリマーおよびコポリマー、ヒドロキシエチルアクリレートのホモポリマーおよびコポリマー、ヒドロキシプロピルメタクリレートのホモポリマーおよびコポリマー、ヒドロキシプロピルアクリレートのホモポリマーおよびコポリマー、ヒドロキシブチルメタクリレートのホモポリマーおよびコポリマー、ヒドロキシブチルアクリレートのホモポリマーおよびコポリマー、ポリエチレンオキシド類、ポリ（プロピレンオキシド）類、ポリビニルアルコール（ＰＶＡ）類、ならびに加水分解度が少なくとも６０％、好ましくは少なくとも８０％の加水分解ポリビニルアセテート、ポリビニルホルマール、ポリビニルブチラール、ポリビニルピロリドン、アクリルアミドのホモポリマーおよびコポリマー、メタクリルアミドのホモポリマーおよびポリマー、Ｎ−メチロールアクリルアミドのホモポリマーおよびコポリマー、２−アクリルアミド−２−メチルプロパンスルホン酸およびその塩等を挙げることができる。
【００６１】
親水性樹脂の画像形成層中への添加量は、画像形成層固形分の２〜４０％が好ましく、３〜３０％がさらに好ましい。この範囲内で良好な機上現像性と高耐刷性が得られる。
【００６２】
本発明の画像形成層には、上記の他に、光を吸収して発熱する光熱変換剤、無機微粒子、着色剤、可塑剤など、感度の向上、親水性の程度の制御、画像形成層の物理的強度の向上、層を構成する組成物相互の分散性の向上、塗布性の向上、印刷適性の向上、製版作業性の便宜上などの種々の目的の化合物を添加することができる。以下これらについて説明する。
【００６３】
光熱変換剤としては、７００ｎｍ以上の光を吸収する物質であればよく、種々の顔料や染料を用いる事ができる。顔料としては、市販の顔料及びカラーインデックス（Ｃ．Ｉ．）便覧、「最新顔料便覧」（日本顔料技術協会編、１９７７年刊）、「最新顔料応用技術」（ＣＭＣ出版、１９８６年刊）、「印刷インキ技術」（ＣＭＣ出版、１９８４年刊）に記載されている顔料が利用できる。
【００６４】
顔料の種類としては、黒色顔料、褐色顔料、赤色顔料、紫色顔料、青色顔料、緑色顔料、蛍光顔料、金属粉顔料、その他、ポリマー結合色素が挙げられる。具体的には、不溶性アゾ顔料、アゾレーキ顔料、縮合アゾ顔料、キレートアゾ顔料、フタロシアニン系顔料、アントラキノン系顔料、ペリレン及びペリノン系顔料、チオインジゴ系顔料、キナクリドン系顔料、ジオキサジン系顔料、イソインドリノン系顔料、キノフタロン系顔料、染付けレーキ顔料、アジン顔料、ニトロソ顔料、ニトロ顔料、天然顔料、蛍光顔料、無機顔料、カーボンブラック等が使用できる。
【００６５】
これら顔料は表面処理をせずに用いてもよく、表面処理をほどこして用いてもよい。表面処理の方法には親水性樹脂や親油性樹脂を表面コートする方法、界面活性剤を付着させる方法、反応性物質（例えば、シリカゾル、アルミナゾル、シランカップリング剤やエポキシ化合物、イソシアネート化合物等）を顔料表面に結合させる方法等が考えられる。上記の表面処理方法は、「金属石鹸の性質と応用」（幸書房）、「印刷インキ技術」（ＣＭＣ出版、１９８４年刊）及び「最新顔料応用技術」（ＣＭＣ出版、１９８６年刊）に記載されている。
【００６６】
本発明の画像形成層に添加する顔料としては、特に、水溶性又は親水性の樹脂と分散しやすく、かつ親水性を損わないように親水性樹脂やシリカゾルで表面がコートされたカーボンブラックが有用である。
【００６７】
顔料の粒径は０.０１μｍ〜１μｍの範囲にあることが好ましく、０．０１μｍ〜０．５μｍの範囲にあることが更に好ましい。顔料を分散する方法としては、インク製造やトナー製造等に用いられる公知の分散技術が使用できる。分散機としては、超音波分散器、サンドミル、アトライター、パールミル、スーパーミル、ボールミル、インペラー、デスパーザー、ＫＤミル、コロイドミル、ダイナトロン、３本ロールミル、加圧ニーダー等が挙げられる。詳細は、「最新顔料応用技術」（ＣＭＣ出版、１９８６年刊）に記載がある。
【００６８】
染料としては、市販の染料及び文献（例えば「染料便覧」有機合成化学協会編集、昭和４５年刊、「化学工業」１９８６年５月号Ｐ．４５〜５１の「近赤外吸収色素」、「９０年代機能性色素の開発と市場動向」第２章２．３項（１９９０）シーエムシー）又は特許に記載されている公知の染料が利用できる。具体的には、アゾ染料、金属錯塩アゾ染料、ピラゾロンアゾ染料、アントラキノン染料、フタロシアニン染料、カルボニウム染料、キノンイミン染料、ポリメチン染料、シアニン染料などの赤外線吸収染料が好ましい。
【００６９】
例えば、特開昭５８−１２５２４６号、特開昭５９−８４３５６号、特開昭６０−７８７８７号、特開昭５８−１７３６９６号、特開昭５８−１９４５９５号、特開昭５９−２１６１４６号、英国特許４３４，８７５号、米国特許第４，９７３，５７２号等に記載されているシアニン染料、米国特許第４，７５６，９９３号記載のシアニン染料やアゾメチン染料、特開昭５８−１８１６９０号等に記載されているメチン染料、特開昭５８−１１２７９３号、特開昭５８−２２４７９３号、特開昭５９−４８１８７号、特開昭５９−７３９９６号、特開昭６０−５２９４０号、特開昭６０−６３７４４号等に記載されているナフトキノン染料、特開昭５８−１１２７９２号等に記載されているスクワリリウム染料、特開平１１−２３５８８３号記載のフタロシアニン化合物や特開平１０−２６８５１２号記載の各種の染料を挙げることができる。
【００７０】
また、染料として米国特許第５，１５６，９３８号記載の近赤外吸収増感剤も好適に用いられ、また、米国特許第３，８８１，９２４号記載の置換されたアリールベンゾ（チオ）ピリリウム塩、特開昭５７−１４２６４５号記載のトリメチンチアピリリウム塩、特開昭５８−１８１０５１号、特開昭５８−２２０１４３号、特開昭５９−４１３６３号、特開昭５９−８４２４８号、特開昭５９−８４２４９号、特開昭５９−１４６０６３号、特開昭５９−１４６０６１号、特公平５−１３５１４号、特公平５−１９７０２号に記載されているピリリウム系化合物、米国特許第４，２８３，４７５号に記載のペンタメチンチオピリリウム塩等や、エポリン社製エポライトIII−１７８、エポライトIII−１３０、エポライトIII−１２５等も好ましく用いられる。
【００７１】
これらの中で、親水性の画像形成層に添加するのに特に好ましい染料は水溶性基を有する染料で、以下に具体例を構造式で示すが、これらに限定されない。
【００７２】
【化５】

【００７３】
【化６】

【００７４】
上記の有機系の光熱変換剤は、画像形成層中に３０％まで添加することができる。好ましくは３〜２５％であり、特に好ましくは４〜２０％である。この範囲内で、良好な感度が得られる。
【００７５】
本発明の画像形成層等には、光熱変換剤として金属微粒子を用いることもできる。金属微粒子の多くは、光熱変換性であって、かつ自己発熱性でもある。好ましい金属微粒子として、Ｓｉ、Ａｌ、Ｔｉ、Ｖ、Ｃｒ、Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ、Ｚｎ、Ｙ、Ｚｒ、Ｍｏ、Ａｇ、Ａｕ、Ｐｔ、Ｐｄ、Ｒｈ、Ｉｎ、Ｓｎ、Ｗ、Ｔｅ、Ｐｂ、Ｇｅ、Ｒｅ、Ｓｂの単体または合金もしくはそれらの酸化物、硫化物の微粒子が挙げられる。
【００７６】
これらの金属微粒子を構成する金属の中でも好ましい金属は、光照射によって熱融着し易い融点がおよそ１０００℃以下で赤外、可視または紫外線領域に吸収をもつ金属、たとえばＲｅ、Ｓｂ、Ｔｅ、Ａｕ、Ａｇ、Ｃｕ、Ｇｅ、ＰｂおよびＳｎである。
【００７７】
また、とくに好ましいのは、融点も比較的低く、熱線に対する吸光度も比較的高い金属の微粒子、たとえばＡｇ、Ａｕ、Ｃｕ、Ｓｂ、ＧｅおよびＰｂで、とくに好ましい元素はＡｇ、ＡｕおよびＣｕが挙げられる。
【００７８】
また、例えばＲｅ、Ｓｂ、Ｔｅ、Ａｕ、Ａｇ、Ｃｕ、Ｇｅ、Ｐｂ、Ｓｎ等の低融点金属の微粒子とＴｉ、Ｃｒ、Ｆｅ、Ｃｏ、Ｎｉ、Ｗ、Ｇｅ等の自己発熱性金属の微粒子を混合使用する等、２種以上の光熱変換物質で構成されていてもよい。また、Ａｇ、Ｐｔ、Ｐｄ等微小片としたときに光吸収がとくに大きい金属種の微小片と他の金属微小片を組み合わせて用いることは好ましい。
【００７９】
以上に述べた金属単体および合金の微粒子は、表面を親水性化処理することによって、本発明の効果がより発揮される。表面親水性化の手段は、親水性でかつ粒子への吸着性を有する化合物、例えば界面活性剤で表面処理したり、粒子の構成物質と反応する親水性基を持つ物質で表面処理したり、保護コロイド性の親水性高分子皮膜を設ける等の方法を用いることができる。特に好ましいのは、表面シリケート処理であり、例えば鉄微粒子の場合は、７０℃のケイ酸ナトリウム（３％）水溶液に３０秒浸漬する方法によって表面を十分に親水性化することができる。他の金属微粒子も同様の方法で表面シリケート処理を行うことができる。
【００８０】
これらの粒子の粒径は、好ましくは１０μｍ以下、より好ましくは０．００３〜５μｍ、特に好ましくは０．０１〜３μｍである。この範囲内で、良好な感度と解像力が得られる。
【００８１】
本発明において、これらの金属微粒子を光熱変換剤として用いる場合、その添加量は、好ましくは画像形成層固形分の５％以上であり、より好ましくは１０％以上で用いられる。この範囲内で高い感度が得られる。
【００８２】
本発明の画像形成層には無機微粒子を添加してもよく、無機微粒子としては、シリカ、アルミナ、酸化マグネシウム、酸化チタン、炭酸マグネシウム、アルギン酸カルシウムもしくはこれらの混合物などが好適な例として挙げられ、これらは光熱変換性でなくても皮膜の強化や表面粗面化による界面接着性の強化などに用いることができる。
【００８３】
無機微粒子の平均粒径は５ｎｍ〜１０μｍのものが好ましく、より好ましくは１０ｎｍ〜１μｍである。粒径がこの範囲内で、樹脂微粒子や光熱変換剤の金属微粒子とも親水性樹脂内に安定に分散し、画像形成層の膜強度を充分に保持し、印刷汚れを生じにくい親水性に優れた非画像部を形成できる。
【００８４】
このような無機微粒子は、コロイダルシリカ分散物などの市販品として容易に入手できる。無機微粒子の画像形成層への含有量は、画像形成層の全固形分の１．０〜７０％が好ましく、より好ましくは５．０〜５０％である。
【００８５】
本発明の画像形成層には、画像形成後、画像部と非画像部の区別をつきやすくするため、可視光域に大きな吸収を持つ染料を画像の着色剤として使用することができる。具体的には、オイルイエロー＃１０１、オイルイエロー＃１０３、オイルピンク＃３１２、オイルグリーンＢＧ、オイルブルーＢＯＳ、オイルブルー＃６０３、オイルブラックＢＹ、オイルブラックＢＳ、オイルブラックＴ−５０５（以上オリエント化学工業（株）製）、ビクトリアピュアブルー、クリスタルバイオレット（ＣＩ４２５５５）、メチルバイオレット（ＣＩ４２５３５）、エチルバイオレット、ローダミンＢ（ＣＩ１４５１７０Ｂ）、マラカイトグリーン（ＣＩ４２０００）、メチレンブルー（ＣＩ５２０１５）等、および特開昭６２−２９３２４７号に記載されている染料を挙げることができる。また、フタロシアニン系顔料、アゾ系顔料、酸化チタンなどの顔料も好適に用いることができる。添加量は、画像形成層の全固形分に対し、０．０１〜１０％の割合である。
【００８６】
本発明の画像形成層には、必要に応じ、塗膜の柔軟性等を付与するために可塑剤を加えることができる。例えば、ポリエチレングリコール、クエン酸トリブチル、フタル酸ジエチル、フタル酸ジブチル、フタル酸ジヘキシル、フタル酸ジオクチル、リン酸トリクレジル、リン酸トリブチル、リン酸トリオクチル、オレイン酸テトラヒドロフルフリル等が用いられる。
【００８７】
マイクロカプセルを画像形成層に添加する場合、内包物が溶解し、かつ壁材が膨潤する溶剤をマイクロカプセル分散媒中に添加することができる。このような溶剤によって、内包された熱反応性官能基を有する化合物の、マイクロカプセル外への拡散が促進される。このような溶剤としては、マイクロカプセル分散媒、マイクロカプセル壁の材質、壁厚および内包物に依存するが、多くの市販されている溶剤から容易に選択することができる。例えば架橋ポリウレア、ポリウレタン壁からなる水分散性マイクロカプセルの場合、アルコール類、エーテル類、アセタール類、エステル類、ケトン類、多価アルコール類、アミド類、アミン類、脂肪酸類などが好ましい。
【００８８】
具体的化合物としては、メタノール、エタノール、第３ブタノール、n−プロパノール、テトラヒドロフラン、乳酸メチル、乳酸エチル、メチルエチルケトン、プロピレングリコールモノメチルエーテル、エチレングリコールジエチルエーテル、エチレングリコールモノメチルエーテル、γ−ブチルラクトン、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ，Ｎ−ジメチルアセトアミドなどがあるが、これらに限られない。またこれらの溶剤を２種以上用いても良い。
【００８９】
マイクロカプセル分散液には溶解しないが、前記溶剤を混合すれば溶解する溶剤も用いることができる。添加量は、素材の組み合わせにより決まるものであるが、適性値より少ない場合は、画像形成が不十分となり、多い場合は分散液の安定性が劣化する。通常、塗布液の５〜９５％が有効であり好ましい範囲は、１０〜９０％、より好ましい範囲は１５〜８５％である。
【００９０】
本発明の画像形成層に、熱反応性官能基を有するポリマー微粒子あるいはマイクロカプセルを用いる場合は、必要に応じてこれらの反応を開始あるいは促進する化合物を添加することができる。反応を開始あるいは促進する化合物としては、熱によりラジカルあるいはカチオンを発生するような化合物を挙げることができ、例えば、ロフィンダイマー、トリハロメチル化合物、過酸化物、アゾ化合物、ジアゾニウム塩あるいはジフェニルヨードニウム塩などを含んだオニウム塩、アシルホスフィン、イミドスルホナートなどが挙げられる。これらの化合物は、画像形成層固形分の１〜２０％の範囲で添加することができる。好ましくは３〜１０％の範囲である。この範囲内で、機上現像性を損なわず、良好な反応開始あるいは促進効果が得られる。
【００９１】
本発明の画像形成層は、必要な上記各成分を水、又は必要に応じて有機溶剤を加えた混合溶剤に溶解又は分散して塗布液を調製し、塗布される。塗布液の固形分濃度は、好ましくは１〜５０％である。
【００９２】
本発明の画像形成層塗布液には、塗膜面状など、塗布性を良化するため、必要に応じて、界面活性剤、例えば、特開昭６２−１７０９５０号に記載されているようなフッ素系界面活性剤を添加することができる。好ましい添加量は、画像形成層固形分の０．０１〜１％である。
【００９３】
塗布する方法としては、種々の方法を用いることができる。例えば、バーコーター塗布、回転塗布、スプレー塗布、カーテン塗布、ディップ塗布、エアーナイフ塗布、ブレード塗布、ロール塗布等を挙げられる。塗布、乾燥後に得られる支持体上の画像形成層の塗布量（固形分）は、用途によって異なるが、一般的に０．５〜５．０ｇ／ｍ²が好ましく、０．５〜２．０ｇ／ｍ²がより好ましい。
【００９４】
本発明に用いる支持体は、親水性表面を有する基板、又は親水層の塗布などによって親水性表面を付与された基板である。具体的には、紙、プラスチック（例えば、ポリエチレン、ポリプロピレン、ポリスチレン等）がラミネートされた紙、金属板（例えば、アルミニウム、亜鉛、銅等）、プラスチックフィルム（例えば、二酢酸セルロース、三酢酸セルロース、プロピオン酸セルロース、酪酸セルロース、酢酸酪酸セルロース、硝酸セルロース、ポリエチレンテレフタレート、ポリエチレン、ポリスチレン、ポリプロピレン、ポリカーボネート、ポリビニルアセタール等）、上記の如き金属がラミネート若しくは蒸着された紙またはプラスチックフィルム、又はこれらの基板に親水層を塗布されたものである。特に好ましい支持体としては、アルミニウム板及び親水層を塗布されたポリエステルフィルムが挙げられる。
【００９５】
該アルミニウム板は、純アルミニウム板およびアルミニウムを主成分とし、微量の異元素を含む合金板であり、さらにはアルミニウムまたはアルミニウム合金の薄膜にプラスチックがラミネートされているものである。アルミニウム合金に含まれる異元素には、ケイ素、鉄、マンガン、銅、マグネシウム、クロム、亜鉛、ビスマス、ニッケル、チタン等がある。合金中の異元素の含有量は高々１０％以下である。また、ＤＣ鋳造法を用いたアルミニウム鋳塊からのアルミニウム板でも、連続鋳造法による鋳塊からのアルミニウム板であっても良い。しかし、本発明に適用されるアルミニウム板は、従来より公知公用の素材のアルミニウム板をも適宜に利用することができる。
【００９６】
本発明で用いられる上記の基板の厚みは０．０５ｍｍ〜０．６ｍｍ、好ましくは０．１ｍｍ〜０．４ｍｍ、特に好ましくは０．１５ｍｍ〜０．３ｍｍである。
【００９７】
アルミニウム板を使用するに先立ち、表面の粗面化、陽極酸化等の表面処理をすることが好ましい。表面処理により、親水性の向上および画像形成層との接着性の確保が容易になる。
【００９８】
アルミニウム板表面の粗面化処理は、種々の方法により行われるが、例えば、機械的に粗面化する方法、電気化学的に表面を溶解粗面化する方法および化学的に表面を選択溶解させる方法により行われる。機械的方法としては、ボール研磨法、ブラシ研磨法、ブラスト研磨法、バフ研磨法等の公知の方法を用いることができる。化学的方法としては、特開昭５４−３１１８７号公報に記載されているような鉱酸のアルミニウム塩の飽和水溶液に浸漬する方法が適している。また、電気化学的な粗面化法としては塩酸または硝酸等の酸を含む電解液中で交流または直流により行う方法がある。また、特開昭５４−６３９０２号に開示されているように混合酸を用いた電解粗面化方法も利用することができる。
【００９９】
上記の如き方法による粗面化は、アルミニウム板の表面の中心線平均粗さ（Ｒａ）が０．２〜１．０μｍとなるような範囲で施されることが好ましい。
【０１００】
粗面化されたアルミニウム板は必要に応じて水酸化カリウムや水酸化ナトリウム等の水溶液を用いてアルカリエッチング処理がされ、さらに中和処理された後、所望により耐摩耗性を高めるために陽極酸化処理が施される。
【０１０１】
アルミニウム板の陽極酸化処理に用いられる電解質としては、多孔質酸化皮膜を形成する種々の電解質の使用が可能で、一般的には硫酸、塩酸、蓚酸、クロム酸もしくはそれらの混酸が用いられる。それらの電解質の濃度は電解質の種類によって適宜決められる。
【０１０２】
陽極酸化の処理条件は、用いる電解質により種々変わるので一概に特定し得ないが、一般的には電解質の濃度が１〜８０％溶液、液温は５〜７０℃、電流密度５〜６０Ａ／dｍ²、電圧１〜１００Ｖ、電解時間１０秒〜５分の範囲であれば適当である。形成される酸化皮膜量は、１．０〜５．０ｇ／ｍ²、特に１．５〜４．０ｇ／ｍ²であることが好ましい。
【０１０３】
本発明で用いられる支持体としては、上記のような表面処理をされ陽極酸化皮膜を有する基板そのままでも良いが、上層との接着性、親水性、汚れ難さ、断熱性等の一層の改良のため、必要に応じて、特願２０００−６５２１９号や特願２０００−１４３３８７号に記載されている陽極酸化皮膜のマイクロポアの拡大処理、マイクロポアの封孔処理、および親水性化合物を含有する水溶液に浸漬する表面親水化処理等を適宜選択して行うことができる。
【０１０４】
上記親水化処理のための好適な親水性化合物としては、ポリビニルホスホン酸、スルホン酸基をもつ化合物、糖類化合物、クエン酸、アルカリ金属珪酸塩、フッ化ジルコニウムカリウム、リン酸塩／無機フッ素化合物等を挙げることができる。
【０１０５】
本発明の支持体としてポリエステルフィルムなど表面の親水性が不十分な支持体を用いる場合は、親水層の塗布等により表面を親水性にする必要がある。親水層としては、特願２０００−１０８１０号に記載の、ベリリウム、マグネシウム、アルミニウム、珪素、チタン、硼素、ゲルマニウム、スズ、ジルコニウム、鉄、バナジウム、アンチモンおよび遷移金属から選択される少なくとも一つの元素の酸化物または水酸化物のコロイドを含有する塗布液を塗布してなる親水層が好ましい。中でも、珪素の酸化物又は水酸化物のコロイドを含有する塗布液を塗布してなる親水層が好ましい。
【０１０６】
本発明においては、画像形成層を塗布する前に、必要に応じて、特願２０００−１４３３８７号に記載の、例えばホウ酸亜鉛等の水溶性金属塩のような無機下塗層、又は例えばカルボキシメチルセルロース、デキストリン、ポリアクリル酸などの含有する有機下塗層が設けられてもかまわない。又、この下塗層には、前記光熱変換剤を含有させてもよい。
【０１０７】
本発明の平版印刷版用原版は、保存時の親油性物質による汚染や取り扱い時の手指の接触による指紋跡汚染等から親水性の画像形成層表面を保護するため、画像形成層上に親水性オーバーコート層を設けることができる。
【０１０８】
本発明に使用される親水性オーバーコート層は印刷機上で容易に除去できるものであり、水溶性樹脂、または水溶性樹脂を部分的に架橋した水膨潤性樹脂から選ばれた樹脂を含有する。
【０１０９】
かかる水溶性樹脂は、水溶性の天然高分子および合成高分子から選ばれ、水溶性樹脂単独もしくは架橋剤とともに用いて、塗布乾燥された皮膜がフィルム形成能を有するものである。
【０１１０】
本発明に好ましく用いられる水溶性樹脂の具体例としては、天然高分子では、アラビアガム、水溶性大豆多糖類、繊維素誘導体（例えば、カルボキシメチルセルローズ、カルボキシエチルセルローズ、メチルセルローズ等）、その変性体、ホワイトデキストリン、プルラン、酵素分解エーテル化デキストリン等、合成高分子では、ポリビニルアルコール（ポリ酢酸ビニルの加水分解率６５％以上のもの）、ポリアクリル酸、そのアルカリ金属塩もしくはアミン塩、ポリアクリル酸共重合体、そのアルカリ金属塩もしくはアミン塩、ポリメタクリル酸、そのアルカリ金属塩もしくはアミン塩、ビニルアルコール／アクリル酸共重合体およびそのアルカリ金属塩もしくはアミン塩、ポリアクリルアミド、その共重合体、ポリヒドロキシエチルアクリレート、ポリビニルピロリドン、その共重合体、ポリビニルメチルエーテル、ビニルメチルエーテル／無水マレイン酸共重合体、ポリ−２−アクリルアミド−２−メチル−１−プロパンスルホン酸、そのアルカリ金属塩もしくはアミン塩、ポリ−２−アクリルアミド−２−メチル−１−プロパンスルホン酸共重合体、そのアルカリ金属塩もしくはアミン塩、等を挙げることができる。目的に応じて、これらの樹脂を二種以上混合して用いることもできる。しかし、本発明はこれらの例に限定されるものではない。
【０１１１】
水溶性樹脂の少なくとも１種以上を部分架橋し、画像形成層上にオーバーコート層を形成する場合、架橋は、水溶性樹脂の有する反応性官能基を用いて架橋反応することにより行われる。架橋反応は、共有結合性の架橋であっても、イオン結合性の架橋であってもよい。
【０１１２】
架橋により、オーバーコート層表面の粘着性が低下して平版印刷版用原版の取り扱い性がよくなるが、架橋が進み過ぎるとオーバーコート層が親油性に変化して、印刷機上におけるオーバーコート層の除去が困難になるので、適度な部分架橋が好ましい。好ましい部分架橋の程度は、２５℃の水中に印刷用原版を浸したときに、３０秒〜１０分間では親水性オーバーコート層が溶出せず残存しているが、１０分以上では溶出が認められる程度である。
【０１１３】
架橋反応に用いられる化合物（架橋剤）としては、架橋性を有する公知の多官能性化合物が挙げられ、ポリエポキシ化合物、ポリアミン化合物、ポリイソシアナート化合物、ポリアルコキシシリル化合物、チタネート化合物、アルデヒド化合物、多価金属塩化合物、ヒドラジン等が挙げられる。
【０１１４】
架橋剤は単独または２種以上を混合して使用することが可能である。架橋剤のうち特に好ましい架橋剤は、水溶性の架橋剤であるが、非水溶性のものは分散剤によって水に分散して使用することができる。
【０１１５】
特に好ましい水溶性樹脂と架橋剤の組み合わせとしては、カルボン酸含有水溶性樹脂／多価金属化合物、カルボン酸含有水溶性樹脂／水溶性エポキシ樹脂、水酸基含有樹脂／ジアルデヒド類を挙げられる。
【０１１６】
架橋剤の好適な添加量は、水溶性樹脂の２〜１０％である。この範囲内で印刷機上でのオーバーコート層の除去性を損なうことなく、良好な耐水性が得られる。
【０１１７】
上記のオーバーコート層には、感度を向上させるため光熱変換剤を含有させることができる。好ましい光熱変換剤としては、水溶性の赤外線吸収色素が挙げられ、中でも、前記の画像形成層の説明中に構造式で示した赤外線吸収色素が好適に用いられる。
【０１１８】
その他、オーバーコート層には塗布の均一性を確保する目的で、水溶液塗布の場合には主に非イオン系界面活性剤を添加することができる。この様な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、ポリオキシエチレンドデシルエーテル等を挙げることが出来る。上記非イオン界面活性剤のオーバーコート層の全固形物中に占める割合は、０．０５〜５％が好ましく、より好ましくは１〜３％である。
【０１１９】
本発明のオーバーコート層の厚みは、水溶性樹脂が架橋されていない場合は、０．１μｍから４．０μmが好ましく、更に好ましい範囲は０．１μｍから１．０μｍであり、水溶性樹脂が部分架橋されている場合は、０．１〜０．５μｍが好ましく、０．１〜０．３μｍがより好ましい。この範囲内で、印刷機上でのオーバーコート層の除去性を損なうことなく、親油性物質による画像形成層の汚染を防止できる。
【０１２０】
本発明の平版印刷版用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。
【０１２１】
本発明の平版印刷版用原版は、レーザー出力が０．１〜３００Ｗのレーザーで照射をすることができる。また、パルスレーザーを用いる場合には、ピーク出力が１０００Ｗ、好ましくは２０００Ｗのレーザーを照射するのが好ましい。この場合の露光量は、印刷用画像で変調する前の面露光強度が０．１〜１０Ｊ／ｃｍ²の範囲であることが好ましく、０．３〜１Ｊ／ｃｍ²の範囲であることがより好ましい。支持体が透明である場合は、支持体の裏側から支持体を通して露光することもできる。
【０１２２】
画像露光された本発明の平版印刷版用原版は、それ以上の処理なしに印刷機に装着された後、湿し水とインキを供給し、さらに紙を供給する通常の印刷開始操作によって機上現像され、続いて印刷することができる。
【０１２３】
また、本発明の平版印刷版用原版は、印刷機の版胴上に取りつけた後に、印刷機に搭載されたレーザーにより露光し、続いて機上現像し、印刷するシステムにも用いられる。
【０１２４】
また、本発明の平版印刷版用原版は、露光後、水又は適当な水溶液を現像液とする液体現像処理をした後、印刷に用いることも可能である。
【０１２５】
【実施例】
以下、実施例により、本発明を詳細に説明するが、本発明はこれらに限定されるものではない。なお、実施例１、４、１０及び１３は、それぞれ参考例１、４、１０及び１３と読替るものとする。
【０１２６】
微粒子の合成例１：微粒子（１）
酢酸エチル２１．０ｇに、質量平均分子量２０００のフェノールのレゾール樹脂（住友デュレス（株）製ＰＲ−５４０２０）７．５ｇ、アニオン界面活性剤パイオニンA−41C（竹本油脂(株)製）０．１ｇを溶解し、油相を作製した。これに４％のポリビニルアルコール（クラレ（株）製ＰＶＡ２０５）水溶液３６．０ｇの水相を加え、ホモジナイザーを用いて１００００ｒｐｍで１０分間乳化させた。水２４．０ｇを加えた後に、この液を５０℃で３時間、有機溶剤を飛ばしながら加熱した。固形分濃度を測定したところ１５．０％であった。また樹脂微粒子（１）の平均粒径は０．３μmであった。
【０１２７】
微粒子の合成例２：微粒子（２）
油相成分として、キシレンジイソシアネート４０ｇ、トリメチロールプロパンジアクリレート１０ｇ、アリルメタクリレートとブチルメタクリレートの共重合体（モル比７／３）１０ｇ、パイオニンＡ４１Ｃ（竹本油脂製）０．１ｇ、下記構造のヨードニウム塩２ｇを酢酸エチル６０ｇに溶解した。水相成分として、ＰＶＡ２０５（クラレ製）の４％水溶液を１２０ｇ作製した。油相成分および水相成分をホモジナイザーを用いて1００００ｒｐｍで乳化した。その後、水を４０ｇ添加し、室温で３０分、さらに４０℃で3時間攪拌した。このようにして得られた微粒子（２）分散液の固形分濃度は２０％であり、平均粒径は０．５μmであった。
【０１２８】
【化７】

【０１２９】
微粒子の合成例３：微粒子（３）
撹拌装置、還流装置、温度付き乾燥窒素導入管、滴下装置を備えた１リットルの四つ口フラスコにメチルエチルケチトン４００ｇを仕込み、８０℃に昇温した。この中に、ビニルトルエン８０ｇ、メタクリル酸エチル２３８．９ｇ、メタクリル酸２４．５ｇ、アクリル酸エチル５６．６ｇ、及びアゾビスイソブチロニトリル８ｇをよく混合した溶液を、２時間かけて滴下した。６時間撹拌後、アゾビスイソブチロニトリル０．５ｇを加え、さらに、３時間撹拌することによって、固形分濃度が４９．５％、酸価０．７０ミリ当量／ｇ（ポリマー固体）、質量平均分子量が４００００のアクリルポリマーが得られた。固形分濃度は、試料溶液１部を秤量するとともに、１２０℃で、１時間乾燥後の試料を秤量し、質量比により求めた。質量平均分子量は、ＧＰＣにより測定し、ポリスチレン換算の分子量でもって記した。酸価は、所定量の試料溶液を坪量し、０．１Ｎの水酸化ナトリウム水溶液で滴定して決めた。
【０１３０】
次に、１−メトキシー２−プロパノール／水（８：２質量比）溶剤５０ｇに上記で合成した樹脂(溶剤を除去後)を２０ｇ溶解した後、トリエチルアミンを０．８４ｇ添加した。次に、ポリアクリルアミドを５％含有する水溶液５０ｇを加え、ホモジナイザーを用いて１５０００ｒｐｍで１５分間乳化分散した。さらに減圧下で、６０℃３時間撹拌することにより有機溶剤を除去して、水に分散する微粒子（３）を得た。
【０１３１】
微粒子の合成例４：微粒子（４）
微粒子の合成例３においてトリエチルアミンを１０％の水酸化ナトリウム水溶液３．３ｇに代えた他は、該合成例３と同様にして合成を行い、微粒子（４）の分散物を得た。
【０１３２】
微粒子の合成例５：微粒子（５）
撹拌装置、還流装置、乾燥窒素導入管、温度計を備えた１リットルの四つ口フラスコに「バーノックＤＮ−９８０」〔大日本インキ化学工業（株）製のポリイソシアネートの商品名〕５３３ｇ、２，２−ビス（ヒドロキシメチル）プロピオン酸３３．５ｇ、ジブチル錫ジラウレート０．０５ｇ及び酢酸エチル３００ｇを加え、８０℃で３時間撹拌した。きらにエタノール５０ｇを加えてさらに８０℃で1時間攪拌し、末端イソシアネートを潰し、水中で析出させた。得られたポリマーの酸価は０．５７ミリ当量／ｇ（ポリマー固体）であった。このようにして乾燥固形分比が５０．０％、ＮＣＯ（イソシアネート基）含有率６．８０％なるポリウレタンプレポリマーの溶液が得られた。ＮＣＯ含有率は、所定量の試料溶液を秤量し、測定するイソシアネート基より過剰の濃度既知のジｎ−ブチルアミンの酢酸エチル溶液を一定量加えて反応せしめ、過剰のジｎ−ブチルアミンを濃度既知の塩酸水溶液で逆滴定することによって求めた。
【０１３３】
次に、１−メトキシー２−プロパノール／水（８：２質量比）溶剤５０ｇに上記で合成した樹脂(溶剤を除去後)を２０ｇ溶解した後、トリエチルアミンを１．０４ｇ添加した。次に、ポリアクリル酸を５％含有する水溶液５０ｇを加え、ホモジナイザーを用いて１５０００ｒｐｍで１５分間乳化分散した。さらに減圧下で、６０℃３時間撹拌することで有機溶剤を除去し水に分散する微粒子（５）を得た。
【０１３４】
実施例１〜１５及び比較例１〜５
アルミニウム板（材質ＪＩＳＡ１０５０、厚さ０．２４ｍｍ）を公知の方法を用いて、硝酸浴で電解砂目立て、硫酸浴で陽極酸化した後、ケイ酸塩水溶液による処理を行った。支持体のＲａ（中心線表面粗さ）は０．２５μｍ、陽極酸化皮膜量は２．５ｇ／ｍ²、ケイ素付着量は１０ｍｇ／ｍ²であった。
【０１３５】
上記のアルミ基板上に下記組成の画像形成層塗布液を作成し、ロッドバーを用いて塗布し、６０℃で３分間乾燥して、乾燥塗布量０．８ｇの平版印刷版用原版を作製した。微粒子は上記のように合成した分散物を、１０％になるように蒸留水で希釈して用いた。
【０１３６】
（画像形成層塗布液組成）
微粒子分散物（表１に微粒子の番号で示す） １０ｇ
親水性樹脂（表１に樹脂名を示す） ０．１ｇ
エチレンオキシド化合物（表１に本明細書記載番号で示す）０．０５ｇ
光熱変換剤（本明細書記載のＩＲ−１０） ０．１ｇ
メガファックＦ−１７７（大日本インキ化学工業（株）製
フッ素系界面活性剤）２０％水溶液 ０．０５ｇ
蒸留水（塗布液濃度が７％になるように添加）
【０１３７】
得られた平版印刷版用原版を、水冷式４０Ｗの赤外線半導体レーザーを搭載したクレオ社製トレンドセッター３２２４ＶＦＳにて、出力９Ｗ、外面ドラム回転数２１０ｒｐｍ、版面エネルギー５００ｍＪ／ｍ²、解像度２４００ｄｐｉの条件で露光した後、現像処理することなく、ハイデルベルグ社製印刷機ＳＯＲ―Ｍの版胴に取り付け、湿し水を供給した後、インキを供給し、さらに紙を供給して印刷を行った。機上現像完了までに要した紙の枚数、耐刷枚数、及び印刷物の汚れ（地汚れの有無）の評価結果を、表１に示した。
【０１３８】
【表１】

【０１３９】
【発明の効果】
本発明によれば、デジタル信号に基づいた赤外線走査露光後、処理を行うことなくそのまま印刷機に装着して印刷可能な平版印刷版用原版であって、機上現像性が良好で、印刷汚れし難く、しかも高耐刷な平版印刷版用原版を提供できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a negative lithographic printing plate precursor having a hydrophilic image forming layer on a support. More specifically, the present invention relates to a lithographic printing plate precursor capable of recording an image by infrared scanning exposure based on a digital signal, and mounting the recorded image on a printing machine as it is and making a plate by on-press development.
[0002]
[Prior art]
Numerous studies have been conducted on computer-to-plate (CTP) systems that have made remarkable progress in recent years. In order to further streamline the process and solve the waste liquid treatment problem, lithographic printing plate precursors that can be printed directly on a printing press without being developed after exposure are studied and various methods are proposed. Has been.
[0003]
One method of eliminating the processing step is to mount the exposed printing plate precursor on the plate cylinder of the printing press, and supply dampening water and ink while rotating the plate cylinder to form the image forming layer of the printing plate precursor. There is a method called on-press development that removes the unexposed portion. In other words, after the printing master is exposed, it is mounted on a printing machine as it is, and the development process is completed in a normal printing process. Such a lithographic printing plate precursor suitable for on-press development has an image-forming layer that is soluble in dampening water or an ink solvent, and is visible even when developed on a printing press placed in a bright room. It is necessary to have suitability for handling a bright room without problems such as fogging due to light.
[0004]
For example, Japanese Patent No. 2938397 describes a lithographic printing plate precursor in which a photosensitive layer in which fine particles of a thermoplastic hydrophobic polymer are dispersed in a hydrophilic binder polymer is provided on a hydrophilic support. In this publication, the lithographic printing plate precursor is subjected to infrared laser exposure to form an image by coalescence (fusion) of thermoplastic hydrophobic polymer fine particles by heat, and then the plate is placed on the plate cylinder of a printing press. It is described that it can be developed on-press by mounting, supplying fountain solution and / or ink. This lithographic printing plate precursor also has suitability for handling a bright room because the photosensitive region is an infrared region.
[0005]
[Problems to be solved by the invention]
However, in the image forming method in which the polymer fine particles are fused by the heat generated by exposure as described above, if the on-press development is facilitated, it is difficult to obtain the printing durability, and if the printing durability is increased, the on-press developability and printing are improved. There was a problem that it was difficult to achieve both of them, such as the difficulty of soiling deteriorated. The object of the present invention is to solve this problem. That is, it is to provide a lithographic printing plate precursor that has good on-press developability, is resistant to printing stains, and has high printing durability.
[0006]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have obtained a remarkable effect on the compatibility between the on-press developability and the difficulty of staining and high printing durability by including a compound having an ethylene oxide chain in the image forming layer. The present invention has been found. That is, the present invention is as follows.
[0007]
1. Hydrophobized precursor, hydrophilic resin, photothermal conversion agent that absorbs light of 700 nm or more, and any functional group selected from an anionic functional group and a cationic functional group and an ethylene oxide chain on a hydrophilic support An image forming layer containing a compound havingIn addition, a photothermal conversion agent that absorbs light of 700 nm or more, and a compound having any functional group selected from an anionic functional group and a cationic functional group and an ethylene oxide chain are present outside the hydrophobic precursor.An original for a lithographic printing plate, characterized in that:
2. 2. The lithographic printing plate precursor as described in 1 above, wherein the compound having an ethylene oxide chain has an anionic functional group.
3. Anionic functional group is -SO₃ ⁻The lithographic printing plate precursor as described in 1 or 2 above, wherein.
[0008]
4. Hydrophobized precursor, hydrophilic resin, photothermal conversion agent that absorbs light of 700 nm or more, and any functional group selected from an anionic functional group and a cationic functional group and an ethylene oxide chain on a hydrophilic support An image forming layer containing a compound havingIn addition, a photothermal conversion agent that absorbs light of 700 nm or more, and a compound having any functional group selected from an anionic functional group and a cationic functional group and an ethylene oxide chain are present outside the hydrophobic precursor.The lithographic printing plate precursor is exposed to a solid high-power infrared laser that emits infrared light having a wavelength of 700 to 1200 nm, mounted on a printing machine without further processing, and then supplied with dampening water and ink. A plate making method in which on-press development is performed by a normal printing start operation for supplying paper.
5The solid high power infrared laser is a semiconductor laser or a YAG laser4The plate making method described in 1.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be described in detail. Hereinafter, unless otherwise specified,% indicates mass%.
  The lithographic printing plate precursor of the present invention comprises a hydrophobic support, a hydrophilic resin, a photothermal conversion agent that absorbs light of 700 nm or more, an anionic functional group, and a cationic functional group on a hydrophilic support. Having an image-forming layer containing a compound having any functional group selected from a group and an ethylene oxide chain.In addition, a photothermal conversion agent that absorbs light of 700 nm or more, and a compound having any functional group selected from an anionic functional group and a cationic functional group and an ethylene oxide chain are present outside the hydrophobic precursor.In this specification, other items are also described for reference.
[0010]
The hydrophobizing precursor used in the image forming layer of the present invention is a fine particle capable of converting a hydrophilic image forming layer to hydrophobic when heat is applied, for example, in the hydrophilic image forming layer. Examples thereof include thermoplastic polymer fine particles to be dispersed, thermosetting polymer fine particles, polymer fine particles having a thermoreactive functional group, and microcapsules enclosing a hydrophobic substance. In the case of polymer particles, when the heat is applied, the polymer particles melt or react with each other, and in the case of microcapsules, the capsule wall is destroyed and the hydrophobic substance oozes out of the capsule. The forming layer can be converted to hydrophobic. These fine particles can be used alone or in combination of two or more in the image forming layer.
[0011]
As thermoplastic polymer fine particles suitable for the present invention, Research Disclosure No. 33303 of January 1992, JP-A-9-123387, JP-A-9-131850, JP-A-9-171249, JP-A-9-171250. The thermoplastic polymer fine particles described in the publications and EP931647 can be mentioned as suitable ones. Specific examples of the polymer constituting the polymer fine particle include homopolymers of monomers such as ethylene, styrene, vinyl chloride, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, vinylidene chloride, acrylonitrile, and vinylcarbazole. Mention may be made of copolymers or mixtures thereof. Among them, more preferred are polystyrene and polymethyl methacrylate.
[0012]
As the thermosetting polymer suitable for the thermosetting polymer fine particles of the present invention, a resin having a phenol skeleton, a urea-based resin (for example, urea or a methoxymethylated urea or a derivative of urea with an aldehyde such as formaldehyde) ), Melamine resins (for example, melamine or derivatives thereof formed by aldehydes such as formaldehyde), alkyd resins, unsaturated polyester resins, polyurethane resins, epoxy resins, and the like.
[0013]
Suitable resins having a phenol skeleton include, for example, phenol resins obtained by converting phenol, cresol and the like with aldehydes such as formaldehyde, hydroxystyrene resins, and methacryl having a phenol skeleton such as N- (p-hydroxyphenyl) methacrylamide. Mention may be made of amide or acrylamide resins and methacrylate or acrylate resins having a phenolic skeleton such as p-hydroxyphenyl methacrylate.
Among these, resins having a phenol skeleton, melamine resins, urea resins and epoxy resins are particularly preferable.
[0014]
The average particle diameter of the thermosetting polymer fine particles used in the present invention is preferably 0.01 to 2.0 μm. As a method for synthesizing such fine particles, these compounds are dissolved in a water-insoluble organic solvent, mixed and emulsified with an aqueous solution containing a dispersant, and further heated to form fine particles while flying the organic solvent. There is a way to solidify. Moreover, when synthesizing a thermosetting polymer, it may be made into fine particles. However, it is not restricted to these methods.
[0015]
Examples of the thermally reactive functional group of the polymer fine particle having a thermally reactive functional group used in the present invention include an ethylenically unsaturated group (for example, acryloyl group, methacryloyl group, vinyl group, and allyl group) that undergoes a polymerization reaction, an addition reaction. Is an isocyanate group that performs the reaction or a block thereof and a functional group having an active hydrogen atom that is the reaction partner (for example, an amino group, a hydroxyl group, a carboxyl group, etc.), an epoxy group that also performs an addition reaction, and an amino that is the reaction partner Groups, carboxyl groups or hydroxyl groups, carboxyl groups and hydroxyl groups or amino groups that undergo condensation reactions, and acid anhydrides and amino groups or hydroxyl groups that undergo ring-opening addition reactions. However, any functional group capable of performing any reaction may be used as long as a chemical bond is formed.
[0016]
Examples of the polymer fine particles having a heat-reactive functional group used in the image forming layer of the present invention include acryloyl group, methacryloyl group, vinyl group, allyl group, epoxy group, amino group, hydroxyl group, carboxyl group, isocyanate group, and acid anhydride. And those having a group protecting them. Introduction of these functional groups into the polymer particles may be performed at the time of polymerization, or may be performed using a polymer reaction after the polymerization.
[0017]
When introduced at the time of polymerization, it is preferable to carry out emulsion polymerization or suspension polymerization of the monomer having these functional groups. Specific examples of the monomer having such a functional group include allyl methacrylate, allyl acrylate, vinyl methacrylate, vinyl acrylate, glycidyl methacrylate, glycidyl acrylate, 2-isocyanate ethyl methacrylate, or a block isocyanate based on alcohol thereof, 2-isocyanate ethyl acrylate. Alternatively, block isocyanates such as alcohol, 2-aminoethyl methacrylate, 2-aminoethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, acrylic acid, methacrylic acid, maleic anhydride, bifunctional acrylate, bifunctional methacrylate However, it is not limited to these.
[0018]
Examples of the monomer having no heat-reactive functional group that can be copolymerized with these monomers include styrene, alkyl acrylate, alkyl methacrylate, acrylonitrile, and vinyl acetate. The monomer is not limited as long as it has no monomer.
[0019]
Examples of the polymer reaction used when the introduction of the heat-reactive functional group is performed after the polymerization include a polymer reaction described in WO96-34316.
[0020]
The solidification temperature of the polymer fine particles having these heat-reactive functional groups is preferably 70 ° C. or higher, but more preferably 100 ° C. or higher in view of stability over time. The average particle diameter of the polymer fine particles is preferably 0.01 to 20 μm, more preferably 0.05 to 2.0 μm, and most preferably 0.1 to 1.0 μm. Within this range, good resolution and stability over time can be obtained.
[0021]
The microcapsule used in the present invention contains a hydrophobic substance. As the hydrophobic substance, a compound having a thermally reactive functional group is preferable. Examples of the heat-reactive functional group include the same functional groups as those used for the polymer fine particles having the heat-reactive functional group.
[0022]
The compound having a polymerizable unsaturated group is preferably a compound having at least one ethylenically unsaturated bond, for example, an acryloyl group, a methacryloyl group, a vinyl group, an allyl group, etc., preferably two or more. Are widely known in the industrial field, and these can be used without particular limitation in the present invention. As chemical forms, these are monomers, prepolymers, that is, dimers, trimers and oligomers, mixtures thereof, or copolymers thereof.
[0023]
Examples include unsaturated carboxylic acids (eg, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters and amides thereof, preferably unsaturated carboxylic acids and aliphatic polyvalent Examples include esters with alcohols and amides of unsaturated carboxylic acids and aliphatic polyvalent amines.
[0024]
In addition, an addition reaction product of an unsaturated carboxylic acid ester or unsaturated carboxylic acid amide having a nucleophilic substituent such as a hydroxyl group, an amino group, a mercapto group and the like with a monofunctional or polyfunctional isocyanate or epoxide, and a monofunctional Alternatively, a dehydration condensation product with a polyfunctional carboxylic acid is also preferably used.
[0025]
In addition, an addition reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an isocyanate group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol, and further a halogen group or a tosyloxy group A substitution reaction product of an unsaturated carboxylic acid ester or amide having a leaving substituent such as monofunctional or polyfunctional alcohol, amine and thiol is also suitable.
Another preferred example is a compound obtained by replacing the unsaturated carboxylic acid with unsaturated phosphonic acid or chloromethylstyrene.
[0026]
Specific examples of the polymerizable compound that is an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol include acrylic acid esters such as ethylene glycol diacrylate, triethylene glycol diacrylate, 1,3-butanediol diacrylate, tetra Methylene glycol diacrylate, propylene glycol diacrylate, neopentyl glycol diacrylate, trimethylolpropane diacrylate, trimethylolpropane triacrylate, trimethylolpropane tris (acryloyloxypropyl) ether, trimethylolethane triacrylate, hexanediol diacrylate, 1,4-cyclohexanediol diacrylate, tetraethylene glycol diacrylate, pentaerythritol diacrylate , Pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, sorbitol triacrylate, sorbitol tetraacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, tris (acryloyl) Oxyethyl) isocyanurate, polyester acrylate oligomer and the like.
[0027]
Methacrylic acid esters include tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, Hexanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol dimethacrylate, dipentaerythritol hexamethacrylate, sorbitol trimethacrylate, sorbitol tetramethacrylate, bis [p- (3-methacryloyloxy- 2-hydroxy Propoxy) phenyl] dimethyl methane, bis - [p- (can be given methacryloyloxy ethoxy) phenyl] dimethyl methane.
[0028]
Itaconic acid esters include ethylene glycol diitaconate, propylene glycol diitaconate, 1,3-butanediol diitaconate, 1,4-butanediol diitaconate, tetramethylene glycol diitaconate, pentaerythritol diitaconate And sorbitol tetritaconate.
[0029]
Examples of crotonic acid esters include ethylene glycol dicrotonate, tetramethylene glycol dicrotonate, pentaerythritol dicrotonate, and sorbitol tetradicrotonate. Examples of isocrotonic acid esters include ethylene glycol diisocrotonate, pentaerythritol diisocrotonate, and sorbitol tetraisocrotonate.
[0030]
Examples of maleic acid esters include ethylene glycol dimaleate, triethylene glycol dimaleate, pentaerythritol dimaleate, and sorbitol tetramaleate.
[0031]
Examples of other esters include aliphatic alcohol esters described in JP-B-46-27926, JP-B-51-47334, JP-A-57-196231, JP-A-59-5240, JP Examples thereof include those having an aromatic skeleton described in JP-A-59-5241 and JP-A-2-226149, and those containing an amino group described in JP-A-1-165613.
[0032]
Specific examples of amide monomers of aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis-acrylamide, methylene bis-methacrylamide, 1,6-hexamethylene bis-acrylamide, 1,6-hexamethylene bis. -Methacrylamide, diethylenetriamine trisacrylamide, xylylene bisacrylamide, xylylene bismethacrylamide and the like. Examples of other preferable amide monomers include those having a cyclohexylene structure described in JP-B No. 54-21726.
[0033]
Further, urethane-based addition polymerizable compounds produced by using an addition reaction of isocyanate and hydroxyl group are also suitable. Specific examples thereof include, for example, one molecule described in JP-B-48-41708. Urethane compounds containing two or more polymerizable unsaturated groups in one molecule obtained by adding an unsaturated monomer having a hydroxyl group represented by the following formula (I) to a polyisocyanate compound having two or more isocyanate groups Is mentioned.
[0034]
Formula (I)
CH₂= C (R¹) COOCH₂CH (R²) OH
[0035]
(However, R¹And R²Are respectively H or CH_ThreeIndicates. )
[0036]
Further, urethane acrylates as described in JP-A-51-37193, JP-B-2-32293, JP-B-2-16765, JP-B 58-49860, JP-B 56-17654, JP-B-sho Urethane compounds having an ethylene oxide skeleton described in JP-A-62-39417 and JP-B-62-39418 can also be mentioned as suitable examples.
[0037]
Furthermore, radical polymerizable compounds having an amino structure or a sulfide structure in the molecule described in JP-A-63-277653, JP-A-63-260909, and JP-A-1-105238 should be mentioned as suitable ones. Can do.
[0038]
Examples of other suitable ones include polyester acrylates, epoxy resins and (meth) acrylic as described in JP-A-48-64183, JP-B-49-43191 and JP-A-52-30490. Mention may be made of polyfunctional acrylates and methacrylates such as epoxy acrylates reacted with an acid. Further, specific unsaturated compounds described in JP-B-46-43946, JP-B-1-40337 and JP-A-1-40336, vinylphosphonic acid compounds described in JP-A-2-25493, and the like are also preferable. Can be mentioned. In some cases, compounds containing a perfluoroalkyl group described in JP-A-61-22048 are also preferably used. Further, those introduced as photocurable monomers and oligomers in Journal of Japan Adhesion Association, Vol. 20, No. 7, pages 300 to 308 (1984) can also be suitably used.
[0039]
Suitable epoxy compounds include glycerin polyglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene diglycidyl ether, trimethylolpropane polyglycidyl ether, sorbitol polyglycidyl ether, bisphenols or polyphenols or polyglycidyl ethers of hydrogenated products thereof. Etc.
[0040]
Suitable isocyanate compounds include tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, xylylene diisocyanate, naphthalene diisocyanate, cyclohexanephenylene diisocyanate, hexamethylene diisocyanate, cyclohexyl diisocyanate, or alcohols or amines thereof. Mention may be made of blocked compounds.
[0041]
Suitable amine compounds include ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, propylenediamine, polyethyleneimine and the like.
[0042]
Suitable compounds having a hydroxyl group include compounds having a terminal methylol group, polyhydric alcohols such as pentaerythritol, bisphenols and polyphenols, and the like.
[0043]
Preferred compounds having a carboxyl group include aromatic polyvalent carboxylic acids such as pyromellitic acid, trimellitic acid and phthalic acid, and aliphatic polyvalent carboxylic acids such as adipic acid.
[0044]
Suitable acid anhydrides include pyromellitic acid anhydride and benzophenone tetracarboxylic acid anhydride.
[0045]
Preferable examples of the copolymer of ethylenically unsaturated compounds include a copolymer of allyl methacrylate. For example, allyl methacrylate / methacrylic acid copolymer, allyl methacrylate / ethyl methacrylate copolymer, allyl methacrylate / butyl methacrylate copolymer and the like can be mentioned.
[0046]
As a method for microencapsulation, a known method can be applied. For example, as a method for producing microcapsules, a method using coacervation found in U.S. Pat. Nos. 2,800,547 and 2,800,498, British Patent 990443, U.S. Pat. No. 3,287,154, Japanese Patent Publication Nos. 38-19574, 42-446 No. 42-711, an interfacial polymerization method, US Pat. No. 3,418,250, US Pat. No. 3,660,304, a method of polymer precipitation, US Pat. No. 3,796,669, a method using an isocyanate polyol wall material, US Pat. No. 3,914,511. A method using an isocyanate wall material found in US Pat. No. 4,001,140, US Pat. No. 4,087,376, US Pat. No. 4,089,802, and a method using a urea-formaldehyde-based or urea-formaldehyde-resorcinol-based wall forming material, A method using a wall material such as melamine-formaldehyde resin and hydroxycellulose as shown in Japanese Patent No. 4025445, an in situ method by monomer polymerization as shown in Japanese Patent Publication Nos. 36-9163 and 51-9079, and British Patent No. 930422 Examples thereof include, but are not limited to, the spray drying method found in US Pat. No. 3111407, and the electrolytic dispersion cooling method shown in British Patent Nos. 952807 and 967074.
[0047]
A preferable microcapsule wall used in the present invention has a three-dimensional cross-linking and has a property of swelling with a solvent. From such a viewpoint, the wall material of the microcapsule is preferably polyurea, polyurethane, polyester, polycarbonate, polyamide, and a mixture thereof, and particularly preferably polyurea and polyurethane. A compound having a thermally reactive functional group may be introduced into the microcapsule wall.
[0048]
The average particle size of the microcapsules is preferably 0.01 to 20 μm, more preferably 0.05 to 2.0 μm, and particularly preferably 0.10 to 1.0 μm. Within this range, good resolution and stability over time can be obtained.
[0049]
Such microcapsules may be combined with each other by heat or may not be combined. In short, among the microcapsule inclusions, the one that oozes out of the capsule surface or outside the microcapsule during application, or the one that penetrates into the microcapsule wall may cause a chemical reaction by heat. You may react with the added hydrophilic resin or the added low molecular weight compound. Alternatively, two or more types of microcapsules may be reacted with each other by providing functional groups that can thermally react with different functional groups. Therefore, it is preferable for image formation that the microcapsules are fused and united by heat, but it is not essential.
[0050]
The addition amount of the hydrophobizing precursor to the image forming layer is preferably 20% or more, more preferably 40% or more, in terms of solid content, in any of the above fine particles. Within this range, a good image can be formed and good printing durability can be obtained.
[0051]
As the compound having an ethylene oxide chain used in the image forming layer of the present invention, any of cationic, anionic, nonionic and amphoteric compounds can be suitably used as long as it has an ethylene oxide chain in the molecule. Particularly preferred compounds having an ethylene oxide chain are compounds having an anionic functional group.
[0052]
As the anionic functional group in the anionic compound having an ethylene oxide chain, any functional group having a negative charge can be preferably used.^-, -SO_Three ^-, -OSO_Three ^-, -P (O) O₂ ^2-Is more preferred, -COO^-, -SO_Three ^-, -P (O) O₂ ^2-Is particularly preferred. As long as the ethylene oxide chain is present, any compound can be used as long as the chain number is 1 or more. Among them, the number of ethylene oxide chain chains is preferably 2 or more, particularly preferably 3 or more. A compound. Specific examples of such compounds are described below, but the present invention is not limited to these.
[0053]
[Chemical 1]

[0054]
[Chemical formula 2]

[0055]
[Chemical 3]

[0056]
[Formula 4]

[0057]
The compound having an ethylene oxide chain used in the present invention may be used alone or in combination of two or more. The amount of this compound added to the image forming layer is preferably from 0.1 to 20%, more preferably from 1 to 10% of the solid content of the image forming layer. In this range, good on-press developability and printing durability can be obtained.
[0058]
In the image forming layer of the present invention, a hydrophilic resin can be added to improve the on-press developability and the film strength of the image forming layer. A hydrophilic resin that is not three-dimensionally cross-linked is preferred because of good on-press developability.
[0059]
As hydrophilic resin, what has hydrophilic groups, such as a hydroxyl group, a carboxyl group, a hydroxyethyl group, a hydroxypropyl group, an amino group, an aminoethyl group, an aminopropyl group, a carboxymethyl group, for example is preferable.
[0060]
Specific examples of hydrophilic resins include gum arabic, casein, gelatin, soya gum, starch and derivatives thereof, cellulose derivatives such as hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, carboxymethylcellulose and salts thereof and cellulose acetate, alginic acid and alkali metal salts thereof. Alkaline earth metal salts or ammonium salts, water-soluble urethane resins, water-soluble polyester resins, vinyl acetate-maleic acid copolymers, styrene-maleic acid copolymers, polyacrylic acids and their salts, polymethacrylic acids and their salts , Hydroxyethyl methacrylate homopolymers and copolymers, hydroxyethyl acrylate homopolymers and copolymers, hydroxypropyl methacrylate homopolymers Limers and copolymers, hydroxypropyl acrylate homopolymers and copolymers, hydroxybutyl methacrylate homopolymers and copolymers, hydroxybutyl acrylate homopolymers and copolymers, polyethylene oxides, poly (propylene oxides), polyvinyl alcohol (PVA) s, and Hydrolyzed polyvinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl pyrrolidone, homopolymers and copolymers of acrylamide, homopolymers and polymers of methacrylamide, homopolymers of N-methylol acrylamide having a degree of hydrolysis of at least 60%, preferably at least 80% And copolymers, 2-acrylamido-2-methylpropanesulfonic acid and Mention may be made of the salts and the like.
[0061]
The amount of the hydrophilic resin added to the image forming layer is preferably 2 to 40%, more preferably 3 to 30% of the solid content of the image forming layer. Within this range, good on-press developability and high printing durability can be obtained.
[0062]
In addition to the above, the image forming layer of the present invention includes a photothermal conversion agent that absorbs light to generate heat, inorganic fine particles, a colorant, a plasticizer, etc., to improve sensitivity, control the degree of hydrophilicity, Various objective compounds such as an improvement in physical strength, an improvement in dispersibility between the compositions constituting the layer, an improvement in coatability, an improvement in printability, and a convenience in plate-making workability can be added. These will be described below.
[0063]
The photothermal conversion agent may be any substance that absorbs light of 700 nm or more, and various pigments and dyes can be used. 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.
[0064]
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.
[0065]
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.
[0066]
As the pigment added to the image forming layer of the present invention, carbon black whose surface is coated with a hydrophilic resin or silica sol so as to be easily dispersible with a water-soluble or hydrophilic resin and not to impair the hydrophilic property is particularly used. Useful.
[0067]
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).
[0068]
Examples of the dye include commercially available dyes and literature (for example, “Dye Handbook” edited by the Society for Synthetic Organic Chemistry, published in 1970, “Chemical Industry”, May 1986, P. 45-51, “Near Infrared Absorbing Dye”, “90 Development and market trends of age functional pigments "Chapter 2. 2.3 (1990) CMC) or known dyes described in patents can be used. Specifically, infrared absorbing dyes such as azo dyes, metal complex azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, polymethine dyes, and cyanine dyes are preferable.
[0069]
For example, JP-A-58-125246, JP-A-59-84356, JP-A-60-78787, JP-A-58-173696, JP-A-58-194595, JP-A-59-216146, Cyanine dyes described in British Patent 434,875, US Pat. No. 4,973,572, etc., cyanine dyes and azomethine dyes described in US Pat. No. 4,756,993, JP-A-58-181690, etc. Methine dyes described in JP-A 58-112793, JP-A 58-224793, JP-A 59-48187, JP-A 59-73996, JP-A 60-52940, JP Naphthoquinone dyes described in JP-A-60-63744, etc., squarylium dyes described in JP-A-58-112792, etc., JP-A-11-235883 Various dyes mounting of the phthalocyanine compound and JP 10-268512 Patent forth can be mentioned.
[0070]
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, JP-A-58-181051, JP-A-58-220143, JP-A-59-41363, JP-A-59-84248, JP-A-59-84249, JP-A-59-146063, JP-A-59-146061, JP-B-5-13514, JP-B-5-19702, pyrylium compounds, US Pat. The pentamethine thiopyrylium salt described in No. 283,475, Epolite III-178, Epolite III-130, Epolite III-125, etc. manufactured by Eporin are also preferable. It is needed.
[0071]
Among these, a particularly preferable dye to be added to the hydrophilic image forming layer is a dye having a water-soluble group, and specific examples thereof are shown below by structural formulas, but are not limited thereto.
[0072]
[Chemical formula 5]

[0073]
[Chemical 6]

[0074]
The organic photothermal conversion agent can be added up to 30% in the image forming layer. Preferably it is 3 to 25%, and particularly preferably 4 to 20%. Within this range, good sensitivity can be obtained.
[0075]
In the image forming layer of the present invention, metal fine particles can also be used as a photothermal conversion agent. Many of the metal fine particles are photothermally convertible and self-heating. As preferable metal fine particles, Si, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Mo, Ag, Au, Pt, Pd, Rh, In, Sn, W, Te , Pb, Ge, Re, and Sb alone or an alloy thereof, oxides thereof, and sulfide fine particles.
[0076]
Among the metals constituting these fine metal particles, preferred metals are metals having a melting point of about 1000 ° C. or less that is easily heat-bonded by light irradiation and having absorption in the infrared, visible, or ultraviolet region, such as Re, Sb, Te, Au, and the like. , Ag, Cu, Ge, Pb and Sn.
[0077]
Particularly preferred are fine metal particles such as Ag, Au, Cu, Sb, Ge and Pb, which have a relatively low melting point and a relatively high absorbance to heat rays, and particularly preferred elements are Ag, Au and Cu. .
[0078]
Also, for example, fine particles of low melting point metal such as Re, Sb, Te, Au, Ag, Cu, Ge, Pb, Sn, and fine particles of self-heating metal such as Ti, Cr, Fe, Co, Ni, W, Ge, etc. You may be comprised with 2 or more types of photothermal conversion substances, such as mixing use. In addition, it is preferable to use a combination of a small metal piece having a particularly large light absorption when combined with another fine metal piece such as Ag, Pt, and Pd.
[0079]
The effects of the present invention are further exhibited by subjecting the fine particles of the simple metal and alloy described above to a hydrophilic treatment on the surface. Surface hydrophilization means surface treatment with a hydrophilic compound that has adsorptivity to particles, such as a surfactant, or a surface treatment with a substance having a hydrophilic group that reacts with the constituent material of the particle, A method such as providing a protective colloidal hydrophilic polymer film can be used. Particularly preferred is surface silicate treatment. For example, in the case of iron fine particles, the surface can be sufficiently rendered hydrophilic by a method of dipping in an aqueous solution of sodium silicate (3%) at 70 ° C. for 30 seconds. Other metal fine particles can also be subjected to surface silicate treatment by the same method.
[0080]
The particle diameter of these particles is preferably 10 μm or less, more preferably 0.003 to 5 μm, and particularly preferably 0.01 to 3 μm. Within this range, good sensitivity and resolution can be obtained.
[0081]
In the present invention, when these metal fine particles are used as a photothermal conversion agent, the addition amount thereof is preferably 5% or more, more preferably 10% or more of the solid content of the image forming layer. High sensitivity is obtained within this range.
[0082]
Inorganic fine particles may be added to the image forming layer of the present invention. Examples of the inorganic fine particles include silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate, and a mixture thereof. Even if they are not photothermally convertible, they can be used for strengthening the film or enhancing the interfacial adhesion by surface roughening.
[0083]
The average particle size of the inorganic fine particles is preferably 5 nm to 10 μm, more preferably 10 nm to 1 μm. Within this range, both the resin fine particles and the photothermal conversion agent metal fine particles are stably dispersed in the hydrophilic resin, the film strength of the image forming layer is sufficiently maintained, and the hydrophilicity is less likely to cause printing stains. A non-image part can be formed.
[0084]
Such inorganic fine particles can be easily obtained as a commercial product such as a colloidal silica dispersion. The content of the inorganic fine particles in the image forming layer is preferably 1.0 to 70%, more preferably 5.0 to 50% of the total solid content of the image forming layer.
[0085]
In the image forming layer of the present invention, a dye having a large absorption in the visible light region can be used as an image colorant in order to make it easy to distinguish between an image area and a non-image area after image formation. Specifically, Oil Yellow # 101, Oil Yellow # 103, Oil Pink # 312, Oil Green BG, Oil Blue BOS, Oil Blue # 603, Oil Black BY, Oil Black BS, Oil Black T-505 (orientated chemistry) Kogyo Co., Ltd.), Victoria Pure Blue, Crystal Violet (CI42555), Methyl Violet (CI42535), Ethyl Violet, Rhodamine B (CI145170B), Malachite Green (CI42000), Methylene Blue (CI522015), etc., and JP-A-62-2 And dyes described in No. 293247. Also, pigments such as phthalocyanine pigments, azo pigments, and titanium oxide can be suitably used. The addition amount is 0.01 to 10% of the total solid content of the image forming layer.
[0086]
If necessary, a plasticizer can be added to the image forming layer of the present invention in order to impart flexibility and the like of the coating film. For example, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate and the like are used.
[0087]
When the microcapsules are added to the image forming layer, a solvent capable of dissolving the inclusion and swelling the wall material can be added to the microcapsule dispersion medium. By such a solvent, diffusion of the encapsulated compound having a heat-reactive functional group to the outside of the microcapsule is promoted. Such a solvent depends on the microcapsule dispersion medium, the material of the microcapsule wall, the wall thickness, and the inclusion, but can be easily selected from many commercially available solvents. For example, in the case of a water-dispersible microcapsule comprising a crosslinked polyurea or polyurethane wall, alcohols, ethers, acetals, esters, ketones, polyhydric alcohols, amides, amines, fatty acids and the like are preferable.
[0088]
Specific compounds include methanol, ethanol, tertiary butanol, n-propanol, tetrahydrofuran, methyl lactate, ethyl lactate, methyl ethyl ketone, propylene glycol monomethyl ether, ethylene glycol diethyl ether, ethylene glycol monomethyl ether, γ-butyl lactone, N, There are N-dimethylformamide, N, N-dimethylacetamide, and the like, but not limited thereto. Two or more of these solvents may be used.
[0089]
A solvent that does not dissolve in the microcapsule dispersion but dissolves when the solvent is mixed can also be used. The amount of addition is determined by the combination of materials. When the amount is less than the appropriate value, image formation is insufficient, and when the amount is large, the stability of the dispersion deteriorates. Usually, 5 to 95% of the coating solution is effective, and a preferred range is 10 to 90%, and a more preferred range is 15 to 85%.
[0090]
When polymer fine particles or microcapsules having a heat-reactive functional group are used in the image forming layer of the present invention, a compound that initiates or accelerates these reactions can be added as necessary. Examples of the compound that initiates or accelerates the reaction include compounds that generate radicals or cations by heat, such as lophine dimer, trihalomethyl compound, peroxide, azo compound, diazonium salt, or diphenyliodonium salt. And onium salts, acylphosphine, imide sulfonate and the like. These compounds can be added in the range of 1 to 20% of the solid content of the image forming layer. Preferably it is 3 to 10% of range. Within this range, good reaction initiation or acceleration effect can be obtained without impairing on-press developability.
[0091]
The image forming layer of the present invention is applied by preparing or applying a coating solution by dissolving or dispersing the necessary components described above in water or a mixed solvent to which an organic solvent is added as necessary. The solid content concentration of the coating solution is preferably 1 to 50%.
[0092]
In the image forming layer coating solution of the present invention, a surfactant, for example, as described in JP-A No. 62-170950 is used as necessary in order to improve the coating properties such as the surface of the coating film. A fluorosurfactant can be added. A preferable addition amount is 0.01 to 1% of the solid content of the image forming layer.
[0093]
Various methods can be used as a coating method. Examples thereof include bar coater coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, and roll coating. The coating amount (solid content) of the image forming layer on the support obtained after coating and drying varies depending on the application, but is generally 0.5 to 5.0 g / m.²Is preferred, 0.5 to 2.0 g / m²Is more preferable.
[0094]
The support used in the present invention is a substrate having a hydrophilic surface or a substrate provided with a hydrophilic surface by coating a hydrophilic layer or the like. Specifically, paper, paper laminated with plastic (for example, polyethylene, polypropylene, polystyrene, etc.), metal plate (for example, aluminum, zinc, copper, etc.), plastic film (for example, cellulose diacetate, cellulose triacetate, Cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), a paper or plastic film on which a metal such as the above is laminated or deposited, or a substrate thereof A hydrophilic layer is applied. A particularly preferred support includes a polyester film coated with an aluminum plate and a hydrophilic layer.
[0095]
The aluminum plate is a pure aluminum plate and an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements. Further, a plastic is laminated on a thin film of aluminum or an aluminum alloy. Examples of foreign elements contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is at most 10%. Further, it may be an aluminum plate from an aluminum ingot using a DC casting method or an aluminum plate from an ingot by a continuous casting method. However, as the aluminum plate applied to the present invention, conventionally known and publicly available aluminum plates can be used as appropriate.
[0096]
The thickness of the substrate used in the present invention is 0.05 mm to 0.6 mm, preferably 0.1 mm to 0.4 mm, and particularly preferably 0.15 mm to 0.3 mm.
[0097]
Prior to using the aluminum plate, it is preferable to perform a surface treatment such as roughening the surface or anodizing. By the surface treatment, it becomes easy to improve hydrophilicity and secure adhesion to the image forming layer.
[0098]
The surface roughening treatment of the aluminum plate is performed by various methods. For example, a method of mechanically roughening, a method of electrochemically dissolving and roughening the surface, and a method of selectively dissolving the surface chemically. By the method. As the mechanical method, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. As a chemical method, a method of immersing in a saturated aqueous solution of an aluminum salt of a mineral acid as described in JP-A No. 54-31187 is suitable. Further, as an electrochemical surface roughening method, there is a method of performing alternating current or direct current in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Further, as disclosed in JP-A-54-63902, an electrolytic surface roughening method using a mixed acid can also be used.
[0099]
The roughening by the method as described above is preferably performed in such a range that the center line average roughness (Ra) of the surface of the aluminum plate is 0.2 to 1.0 μm.
[0100]
The roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide, sodium hydroxide or the like, if necessary, and further neutralized, and then anodized to enhance wear resistance as desired. Processing is performed.
[0101]
As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid, or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.
[0102]
The treatment conditions for anodization vary depending on the electrolyte used and cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / dm.²A voltage of 1 to 100 V and an electrolysis time of 10 seconds to 5 minutes are suitable. The amount of oxide film formed is 1.0 to 5.0 g / m.², Especially 1.5-4.0 g / m²It is preferable that
[0103]
As the support used in the present invention, the substrate having the above-mentioned surface treatment and having an anodized film may be used as it is, but further improvement in adhesiveness with the upper layer, hydrophilicity, resistance to contamination, heat insulation, etc. Therefore, if necessary, the micropore enlargement treatment of the anodized film, the micropore sealing treatment described in Japanese Patent Application No. 2000-65219 and Japanese Patent Application No. 2000-143387, and an aqueous solution containing a hydrophilic compound A surface hydrophilization treatment or the like immersed in the substrate can be appropriately selected and performed.
[0104]
Suitable hydrophilic compounds for the hydrophilization treatment include polyvinylphosphonic acid, compounds having sulfonic acid groups, saccharide compounds, citric acid, alkali metal silicates, potassium zirconium fluoride, phosphate / inorganic fluorine compounds, etc. Can be mentioned.
[0105]
When using a support with insufficient surface hydrophilicity such as a polyester film as the support of the present invention, it is necessary to make the surface hydrophilic by coating a hydrophilic layer or the like. The hydrophilic layer includes at least one element selected from beryllium, magnesium, aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony, and transition metals described in Japanese Patent Application No. 2000-10810. A hydrophilic layer formed by applying a coating solution containing an oxide or hydroxide colloid is preferred. Among these, a hydrophilic layer formed by applying a coating solution containing a silicon oxide or hydroxide colloid is preferable.
[0106]
In the present invention, before applying the image forming layer, an inorganic subbing layer described in Japanese Patent Application No. 2000-143387, such as a water-soluble metal salt such as zinc borate, or An organic subbing layer containing methyl cellulose, dextrin, polyacrylic acid or the like may be provided. The undercoat layer may contain the photothermal conversion agent.
[0107]
The lithographic printing plate precursor according to the present invention is hydrophilic on the image forming layer in order to protect the hydrophilic image forming layer surface from contamination with lipophilic substances during storage and fingerprint trace contamination due to finger contact during handling. An overcoat layer can be provided.
[0108]
The hydrophilic overcoat layer used in the present invention can be easily removed on a printing press, and contains a water-soluble resin or a resin selected from water-swellable resins partially crosslinked with water-soluble resins. .
[0109]
Such a water-soluble resin is selected from water-soluble natural polymers and synthetic polymers, and a film coated and dried using a water-soluble resin alone or with a crosslinking agent has film-forming ability.
[0110]
Specific examples of water-soluble resins preferably used in the present invention include natural gums, gum arabic, water-soluble soybean polysaccharides, fiber derivatives (eg, carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose, etc.), and modifications thereof. Synthetic polymers such as body, white dextrin, pullulan, enzymatically degraded etherified dextrin, polyvinyl alcohol (polyvinyl acetate with a hydrolysis rate of 65% or more), polyacrylic acid, its alkali metal salt or amine salt, polyacrylic Acid copolymer, alkali metal salt or amine salt thereof, polymethacrylic acid, alkali metal salt or amine salt thereof, vinyl alcohol / acrylic acid copolymer and alkali metal salt or amine salt thereof, polyacrylamide, copolymer thereof, Polyhydroxyethyl aqua Rate, polyvinyl pyrrolidone, copolymer thereof, polyvinyl methyl ether, vinyl methyl ether / maleic anhydride copolymer, poly-2-acrylamido-2-methyl-1-propanesulfonic acid, alkali metal salt or amine salt thereof, poly Examples include 2-acrylamido-2-methyl-1-propanesulfonic acid copolymer, alkali metal salt or amine salt thereof. Depending on the purpose, two or more of these resins may be mixed and used. However, the present invention is not limited to these examples.
[0111]
When at least one kind of water-soluble resin is partially crosslinked to form an overcoat layer on the image forming layer, the crosslinking is performed by a crosslinking reaction using a reactive functional group of the water-soluble resin. The crosslinking reaction may be a covalent bond or an ionic bond.
[0112]
Crosslinking reduces the adhesiveness of the overcoat layer surface and improves the handleability of the lithographic printing plate precursor, but if the crosslinking proceeds too much, the overcoat layer changes to oleophilic, and the overcoat layer on the printing press Since removal becomes difficult, moderate partial cross-linking is preferred. The preferred degree of partial crosslinking is that when the printing original plate is immersed in water at 25 ° C., the hydrophilic overcoat layer does not elute for 30 seconds to 10 minutes, but elution is observed after 10 minutes or more. Degree.
[0113]
Examples of the compound (crosslinking agent) used in the crosslinking reaction include known polyfunctional compounds having crosslinking properties, such as polyepoxy compounds, polyamine compounds, polyisocyanate compounds, polyalkoxysilyl compounds, titanate compounds, aldehyde compounds, Examples thereof include polyvalent metal salt compounds and hydrazine.
[0114]
Crosslinking agents can be used alone or in admixture of two or more. Among the crosslinking agents, a particularly preferred crosslinking agent is a water-soluble crosslinking agent, but a water-insoluble crosslinking agent can be used by dispersing in water with a dispersant.
[0115]
Particularly preferred combinations of water-soluble resins and crosslinking agents include carboxylic acid-containing water-soluble resins / polyvalent metal compounds, carboxylic acid-containing water-soluble resins / water-soluble epoxy resins, and hydroxyl group-containing resins / dialdehydes.
[0116]
A suitable addition amount of the crosslinking agent is 2 to 10% of the water-soluble resin. Within this range, good water resistance can be obtained without impairing the removability of the overcoat layer on the printing press.
[0117]
The overcoat layer may contain a photothermal conversion agent in order to improve sensitivity. Preferable photothermal conversion agents include water-soluble infrared-absorbing dyes. Among them, infrared-absorbing dyes represented by structural formulas in the description of the image forming layer are preferably used.
[0118]
In addition, a nonionic surfactant can be mainly added to the overcoat layer in the case of aqueous solution coating for the purpose of ensuring the uniformity of coating. Specific examples of such nonionic surfactants include sorbitan tristearate, sorbitan monopalmitate, sorbitan trioleate, stearic acid monoglyceride, polyoxyethylene nonylphenyl ether, polyoxyethylene dodecyl ether and the like. . The proportion of the nonionic surfactant in the total solids of the overcoat layer is preferably 0.05 to 5%, more preferably 1 to 3%.
[0119]
When the water-soluble resin is not crosslinked, the thickness of the overcoat layer of the present invention is preferably 0.1 μm to 4.0 μm, and more preferably 0.1 μm to 1.0 μm. When crosslinked, 0.1 to 0.5 μm is preferable, and 0.1 to 0.3 μm is more preferable. Within this range, contamination of the image forming layer with an oleophilic substance can be prevented without impairing the removability of the overcoat layer on the printing press.
[0120]
The lithographic printing plate precursor of the present invention is image-formed 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, but a semiconductor that emits infrared light having a wavelength of 700 to 1200 nm. Exposure by a solid high-power infrared laser such as a laser or a YAG laser is suitable.
[0121]
The lithographic printing plate precursor of the present invention can be irradiated with a laser having a laser output of 0.1 to 300 W. When a pulse laser is used, it is preferable to irradiate a laser having a peak output of 1000 W, preferably 2000 W. In this case, the exposure amount is 0.1 to 10 J / cm at the surface exposure intensity before modulation with the printing image.²Is preferably in the range of 0.3-1 J / cm²More preferably, it is the range. When the support is transparent, exposure can be performed through the support from the back side of the support.
[0122]
The image-exposed lithographic printing plate precursor of the present invention is mounted on a printing machine without any further processing, then supplied with dampening water and ink, and then on the machine by a normal printing start operation for supplying paper. It can be developed and subsequently printed.
[0123]
The lithographic printing plate precursor according to the present invention is also used in a system for printing on a plate cylinder of a printing machine, exposing to a laser mounted on the printing machine, and subsequently developing and printing on the machine.
[0124]
The lithographic printing plate precursor according to the invention can also be used for printing after exposure and after performing liquid development using water or a suitable aqueous solution as a developer.
[0125]
【Example】
  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these. Examples1, 410 and 13 are reference examples, respectively.1, 410 and 13 shall be read.
[0126]
Fine particle synthesis example 1: fine particles (1)
21.0 g of ethyl acetate, 7.5 g of phenolic resole resin (PR-54020 manufactured by Sumitomo Dureth Co., Ltd.), 0.1 g of anionic surfactant Piion A-41C (manufactured by Takemoto Yushi Co., Ltd.) Was dissolved to prepare an oil phase. An aqueous phase of 36.0 g of 4% polyvinyl alcohol (Kuraray Co., Ltd. PVA205) aqueous solution was added thereto, and emulsified at 10,000 rpm for 10 minutes using a homogenizer. After adding 24.0 g of water, the solution was heated at 50 ° C. for 3 hours while removing the organic solvent. The solid content was measured and found to be 15.0%. The average particle size of the resin fine particles (1) was 0.3 μm.
[0127]
Fine particle synthesis example 2: fine particles (2)
As oil phase components, 40 g of xylene diisocyanate, 10 g of trimethylolpropane diacrylate, 10 g of a copolymer of allyl methacrylate and butyl methacrylate (molar ratio 7/3), 0.1 g of Pionine A41C (manufactured by Takemoto Yushi), iodonium salt having the following structure 2 g was dissolved in 60 g of ethyl acetate. As an aqueous phase component, 120 g of a 4% aqueous solution of PVA205 (manufactured by Kuraray) was prepared. The oil phase component and the aqueous phase component were emulsified at 10,000 rpm using a homogenizer. Thereafter, 40 g of water was added, and the mixture was stirred at room temperature for 30 minutes and further at 40 ° C. for 3 hours. The fine particle (2) dispersion thus obtained had a solid content concentration of 20% and an average particle size of 0.5 μm.
[0128]
[Chemical 7]

[0129]
Fine particle synthesis example 3: fine particles (3)
Into a 1 liter four-necked flask equipped with a stirrer, a reflux device, a dry nitrogen inlet tube with temperature, and a dropping device, 400 g of methyl ethyl ketitol was charged and heated to 80 ° C. Into this, a solution in which 80 g of vinyl toluene, 238.9 g of ethyl methacrylate, 24.5 g of methacrylic acid, 56.6 g of ethyl acrylate, and 8 g of azobisisobutyronitrile were well mixed was dropped over 2 hours. After stirring for 6 hours, 0.5 g of azobisisobutyronitrile was added, and the mixture was further stirred for 3 hours, whereby the solid content concentration was 49.5%, the acid value was 0.70 meq / g (polymer solid), and the mass An acrylic polymer having an average molecular weight of 40,000 was obtained. The solid content concentration was determined by weighing 1 part of the sample solution and weighing the sample after drying for 1 hour at 120 ° C. and by mass ratio. The mass average molecular weight was measured by GPC and described with a molecular weight in terms of polystyrene. The acid value was determined by weighing a predetermined amount of the sample solution and titrating with a 0.1N sodium hydroxide aqueous solution.
[0130]
Next, 20 g of the resin synthesized above (after removal of the solvent) was dissolved in 50 g of a 1-methoxy-2-propanol / water (8: 2 mass ratio) solvent, and then 0.84 g of triethylamine was added. Next, 50 g of an aqueous solution containing 5% polyacrylamide was added, and the mixture was emulsified and dispersed at 15000 rpm for 15 minutes using a homogenizer. Furthermore, the organic solvent was removed by stirring at 60 ° C. for 3 hours under reduced pressure to obtain fine particles (3) dispersed in water.
[0131]
Fine particle synthesis example 4: fine particles (4)
Synthesis was performed in the same manner as in Synthesis Example 3 except that triethylamine was replaced with 3.3 g of a 10% aqueous sodium hydroxide solution in Fine Particle Synthesis Example 3 to obtain a dispersion of fine particles (4).
[0132]
Fine particle synthesis example 5: fine particles (5)
“Burnock DN-980” [trade name of polyisocyanate manufactured by Dainippon Ink & Chemicals, Inc.] 533 g, 2 in a 1 liter four-necked flask equipped with a stirrer, a reflux device, a dry nitrogen inlet tube, and a thermometer , 2-bis (hydroxymethyl) propionic acid 33.5 g, dibutyltin dilaurate 0.05 g and ethyl acetate 300 g were added and stirred at 80 ° C. for 3 hours. 50 g of ethanol was added to the mixture, and the mixture was further stirred at 80 ° C. for 1 hour to crush the terminal isocyanate and precipitate it in water. The acid value of the obtained polymer was 0.57 meq / g (polymer solid). Thus, a polyurethane prepolymer solution having a dry solid content ratio of 50.0% and an NCO (isocyanate group) content of 6.80% was obtained. The NCO content is determined by weighing a predetermined amount of sample solution, adding a certain amount of an ethyl acetate solution of di-n-butylamine having an excess concentration known from the isocyanate group to be measured, and allowing the excess di-n-butylamine to have a known concentration. Determined by back titration with aqueous hydrochloric acid.
[0133]
Next, 20 g of the resin synthesized above (after removal of the solvent) was dissolved in 50 g of 1-methoxy-2-propanol / water (8: 2 mass ratio) solvent, and 1.04 g of triethylamine was added. Next, 50 g of an aqueous solution containing 5% polyacrylic acid was added, and the mixture was emulsified and dispersed at 15000 rpm for 15 minutes using a homogenizer. Furthermore, the organic solvent was removed by stirring at 60 ° C. for 3 hours under reduced pressure to obtain fine particles (5) dispersed in water.
[0134]
Examples 1-15 and Comparative Examples 1-5
An aluminum plate (material JISA 1050, thickness 0.24 mm) was electrolytically grained with a nitric acid bath and anodized with a sulfuric acid bath using a known method, and then treated with an aqueous silicate solution. Ra (center line surface roughness) of the support is 0.25 μm, and the amount of the anodized film is 2.5 g / m.², Silicon adhesion amount is 10mg / m²Met.
[0135]
An image forming layer coating solution having the following composition was prepared on the above aluminum substrate, applied using a rod bar, and dried at 60 ° C. for 3 minutes to prepare a lithographic printing plate precursor having a dry coating amount of 0.8 g. As the fine particles, the dispersion synthesized as described above was diluted with distilled water to 10% and used.
[0136]
(Image forming layer coating solution composition)
Fine particle dispersion (indicated by the number of fine particles in Table 1) 10 g
Hydrophilic resin (resin names are shown in Table 1) 0.1 g
0.05 g of ethylene oxide compound (indicated in Table 1 by the numbers described in this specification)
Photothermal conversion agent (IR-10 described herein) 0.1 g
MegaFuck F-177 (Dainippon Ink Chemical Co., Ltd.)
Fluorosurfactant) 20% aqueous solution 0.05g
Distilled water (added so that the concentration of the coating solution is 7%)
[0137]
The obtained lithographic printing plate precursor was output by a Creo Trendsetter 3224VFS equipped with a water-cooled 40 W infrared semiconductor laser, output 9 W, outer drum rotation speed 210 rpm, plate energy 500 mJ / m.²After being exposed to a resolution of 2400 dpi, without being developed, it is attached to the plate cylinder of a printing machine SOR-M manufactured by Heidelberg, supplied with dampening water, then supplied with ink, and further supplied with paper for printing. Went. Table 1 shows the evaluation results of the number of sheets of paper required for completion of on-press development, the number of printing durability, and stains on the printed matter (presence or absence of background stains).
[0138]
[Table 1]

[0139]
【The invention's effect】
According to the present invention, there is provided a lithographic printing plate precursor that can be mounted on a printing machine as it is without being processed after infrared scanning exposure based on a digital signal, and has excellent on-press developability and printing stains. Therefore, it is possible to provide a lithographic printing plate precursor which is difficult to perform and has a high printing durability.

Claims (5)

Hydrophobized precursor, hydrophilic resin, photothermal conversion agent that absorbs light of 700 nm or more, and any functional group selected from an anionic functional group and a cationic functional group and an ethylene oxide chain on a hydrophilic support have a image forming layer containing a compound having, and is a compound having any functional group and ethylene oxide chains selected from the photothermal conversion agent and anionic functional groups and cationic functional group absorbs light of at least 700nm An original for a lithographic printing plate, characterized in that it exists outside the hydrophobic precursor .   The lithographic printing plate precursor as claimed in claim 1, wherein the compound having an ethylene oxide chain has an anionic functional group. The lithographic printing plate precursor according to claim 1 or claim 2, characterized in that it is ^- anionic functional group is -SO _3. Hydrophobized precursor, hydrophilic resin, photothermal conversion agent that absorbs light of 700 nm or more, and any functional group selected from an anionic functional group and a cationic functional group and an ethylene oxide chain on a hydrophilic support have a image forming layer containing a compound having, and is a compound having any functional group and ethylene oxide chains selected from the photothermal conversion agent and anionic functional groups and cationic functional group absorbs light of at least 700nm The lithographic printing plate precursor existing outside the hydrophobic precursor is exposed to a solid high-power infrared laser that emits infrared light having a wavelength of 700 to 1200 nm, and is attached to a printing machine without any further treatment, followed by dampening water. And plate-making method in which on-press development is performed by a normal printing start operation for supplying paper and paper. The plate making method according to claim 4 , wherein the solid high-power infrared laser is a semiconductor laser or a YAG laser.