JP2004284140A - Imaging method and image exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging method which can form an image without passing through a liquid development process after image exposure and can obtain a lithographic printing plate with outstanding resistance to plate wear, and an image exposure device best-suited for this method. <P>SOLUTION: In the image exposure device 10, an image corresponding to a digital image information is formed by scanning and exposing to light an original lithographic printing plate 12 with the help of an infrared laser beam based on digital image information. The image recording layer of the original plate 12 contains a microcapsule encapsulating a cationic polymerizable compound, an acid generator and a photothermal converting agent. The image exposure device 10 is equipped with an exposure head 26 opposite to an outer drum 20 and scans/exposes to light the original plate 12 fitted to the outer drum 20 with the help of an IR laser L. In addition, the device 10 is equipped with a preheater 38 for heating (preheating) the whole original plate 12 halfway through a feed route and preheats the original plate 12 before exposure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００７３】
【化２】

【００７４】
【化３】

【００７５】
【化４】

【００７６】
光熱変換剤の添加量は、マイクロカプセル中に添加する場合には、全マイクロカプセル内包物の１〜５０質量％が好ましく、３〜２５質量％がより好ましい。一方、光熱変換剤を画像記録層マトリックス中に添加する場合には、記録層固形分の１〜５０質量％が好ましく、３〜２５質量％がより好ましい。この範囲において、記録層の膜強度を損なうことなく、良好な感度が得られる。
【００７７】
（酸発生剤）
本発明に係る記録層には、画像記録層マトリックス中に、熱により酸を発生し、前記カチオン重合性基の反応を開始、促進する酸発生剤を添加する必要がある。この場合、酸発生剤を前記マイクロカプセル内および画像記録層マトリックス中の少なくとも一方に添加すればよいが、安定性の観点から、カチオン重合性化合物とマイクロカプセル壁を隔てて存在するよう、記録層マトリックス中に添加することが好ましい。
また、酸発生剤は、発生した酸により変色する染料と組み合わせて焼き出し系を形成することもできる。
このような酸発生剤としては、公知の酸前駆体、酸発生剤と呼ばれる化合物が好適に用いられ、例えば、焼き出し画像形成用の酸発生剤、マイクロレジスト等に使用されている酸発生剤等が挙げられる。
【００７８】
より具体的には、特開２００２−２９１６２号、特開２００２−４６３６１号、特開２００２−１３７５６２号などに記載のトリハロメチル置換へテロ環化合物に代表される有機ハロゲン化合物、イミノスルフォネート等に代表される光分解してスルホン酸を発生する化合物、ジスルホン化合物、オニウム塩（例えばヨードニウム塩、ジアゾニウム塩、スルホニウム塩など）を挙げることができる。またこれらの酸を発生する基又は化合物をポリマーの主鎖又は側鎖に導入した化合物を用いることもできる。
以下、具体的例を挙げるが、本発明はこれらに限定されるものではない。
【００７９】
【化５】

【００８０】
【化６】

【００８１】
【化７】

【００８２】
【化８】

【００８３】
【化９】

【００８４】
上記酸発生剤は２種以上を組み合わせて用いることもできる。
酸発生剤の添加量は、画像記録層マトリックス中に添加する場合には、記録層全固形分の０．０１〜２０質量％が好ましく、０．１〜１０質量％がより好ましい。この範囲内で、機上現像性を損なわず、良好な反応開始又は促進効果が得られる。
【００８５】
本発明の方法においては、前記予備加熱工程における予備加熱により、画像露光に用いられる赤外線ビームのエネルギーが支持体に拡散されるのを抑制する効果のみならず、酸発生剤の分解を開始、促進することにより、カプセル壁材が透過性となり、系中に放出されたカチオン重合性化合物と酸との硬化反応の効率が向上する効果も得られる。このため、予備加熱温度は酸発生剤の分解を開始、促進する温度以上とすることが好ましく、分解温度を少なくとも１０℃上回る温度とすることがさらに好ましい。酸発生剤の分解温度は、化合物の種類により異なるが、例えば、ジフェニルヨードニウムトリフルオロメタンスルホン酸（本明細書に例示のＡＩ−７）の場合は、１６０℃程度である。
【００８６】
また、本発明に係る記録層には、焼き出し画像生成のため、酸によって変色する化合物を添加することができる。このような化合物としては、例えばジフェニルメタン系、トリフェニルメタン系、チアジン系、オキサジン系、キサンテン系、アンスラキノン系、イミノキノン系、アゾ系、アゾメチン系等の各種色素が有効に用いられる。
【００８７】
具体例としては、ブリリアントグリーン、エチルバイオレット、メチルグリーン、クリスタルバイオレット、ベイシックフクシン、メチルバイオレット２Ｂ、キナルジンレッド、ローズベンガル、メタニルイエロー、チモールスルホフタレイン、キシレノールブルー、メチルオレンジ、パラメチルレッド、コンゴーフレッド、ベンゾプルプリン４Ｂ、α−ナフチルレッド、ナイルブルー２Ｂ、ナイルブルーＡ、メチルバイオレット、マラカイドグリーン、パラフクシン、ビクトリアピュアブルーＢＯＨ［保土ケ谷化学（株）製］、オイルブルー＃６０３［オリエント化学工業（株）製］、オイルピンク＃３１２［オリエント化学工業（株）製］、オイルレッド５Ｂ［オリエント化学工業（株）製］、オイルスカーレット＃３０８［オリエント化学工業（株）製］、オイルレッドＯＧ［オリエント化学工業（株）製］、オイルレッドＲＲ［オリエント化学工業（株）製］、オイルグリーン＃５０２［オリエント化学工業（株）製］、スピロンレッドＢＥＨスペシャル［保土ケ谷化学工業（株）製］、ｍ−クレゾールパープル、クレゾールレッド、ローダミンＢ、ローダミン６Ｇ、スルホローダミンＢ、オーラミン、４−ｐ−ジエチルアミノフェニルイミノナフトキノン、２−カルボキシアニリノ−４−ｐ−ジエチルアミノフェニルイミノナフトキノン、２−カルボキシステアリルアミノ−４−ｐ−Ｎ，Ｎ−ビス（ヒドロキシエチル）アミノ−フェニルイミノナフトキノン、１−フェニル−３−メチル−４−ｐ−ジエチルアミノフェニルイミノ−５−ピラゾロン、１−β−ナフチル−４−ｐ−ジエチルアミノフェニルイミノ−５−ピラゾロン等の染料やｐ，ｐ’，ｐ”−ヘキサメチルトリアミノトリフェニルメタン（ロイコクリスタルバイオレット）、Ｐｅｒｇａｓｃｒｉｐｔ Ｂｌｕｅ ＳＲＢ（チバガイギー社製）等のロイコ染料が挙げられる。
【００８８】
上記の他に、感熱紙や感圧紙用の素材として知られているロイコ染料も好適なものとして挙げられる。具体例としては、クリスタルバイオレットラクトン、マラカイトグリーンラクトン、ベンゾイルロイコメチレンブルー、２−（Ｎ−フェニル−Ｎ−メチルアミノ）−６−（Ｎ−ｐ−トリル−Ｎ−エチル）アミノ−フルオラン、２−アニリノ−３−メチル−６−（Ｎ−エチル−ｐ−トルイジノ）フルオラン、３，６−ジメトキシフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−５−メチル−７−（Ｎ，Ｎ−ジベンジルアミノ）−フルオラン、３−（Ｎ−シクロヘキシル−Ｎ−メチルアミノ）−６−メチル−７−アニリノフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−６−メチル−７−アニリノフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−６−メチル−７−キシリジノフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−６−メチルー７−クロロフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−６−メトキシ−７−アミノフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−７−（４−クロロアニリノ）フルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−７−クロロフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−７−ベンジルアミノフルオラン、３−（Ｎ，Ｎ−ジエチルアミノ）−７，８−ベンゾフロオラン、３−（Ｎ，Ｎ−ジブチルアミノ）−６−メチル−７−アニリノフルオラン、３−（Ｎ，Ｎ−ジブチルアミノ）−６−メチル−７−キシリジノフルオラン、３−ピペリジノ−６−メチル−７−アニリノフルオラン、３−ピロリジノ−６−メチル−７−アニリノフルオラン、３，３−ビス（１−エチル−２−メチルインドール−３−イル）フタリド、３，３−ビス（１−ｎ−ブチル−２−メチルインドール−３−イル）フタリド、３，３−ビス（ｐ−ジメチルアミノフェニル）−６−ジメチルアミノフタリド、３−（４−ジエチルアミノ−２−エトキシフェニル）−３−（１−エチル−２−メチルインドール−３−イル）−４−ザフタリド、３−（４−ジエチルアミノフェニル）−３−（１−エチル−２−メチルインドール−３−イル）フタリド、などが挙げられる。
酸によって変色する染料の好適な添加量は、それぞれ、記録層固形分に対して０．０１〜１０質量％の割合である。
【００８９】
（親水性樹脂）
本発明に係る記録層マトリックス中には、機上現像性や記録層自体の皮膜強度向上、さらに、電磁波加熱を実施する場合の加熱効率向上のため親水性樹脂を含有させてもよい。
親水性樹脂としては、例えばヒドロキシ基、アミノ基、カルボキシ基、リン酸基、スルホン酸基、アミド基などの親水性基を有するものが好ましい。また、親水性樹脂は、マイクロカプセルに内包されるカチオン重合性化合物が有するカチオン重合性基、あるいは、熱重合性化合物が有する熱反応性基と反応し架橋することによって画像強度が高まり、高耐刷化されるので、これらの官能基と反応する基を有することが好ましい。例えば、カチオン重合性化合物がビニルオキシ基又はエポキシ基を有する場合は、親水性樹脂としては、ヒドロキシ基、カルボキシ基、リン酸基、スルホン酸基などを有するものが好ましい。中でも、ヒドロキシ基又はカルボキシ基を有する親水性樹脂が好ましい。
【００９０】
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、澱粉誘導体、ソヤガム、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及びそのナトリウム塩、セルロースアセテート、アルギン酸ナトリウム、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、ポリアクリル酸類及びそれらの塩、ポリメタクリル酸類及びそれらの塩、ヒドロキシエチルメタクリレートのホモポリマー及びコポリマー、ヒドロキシエチルアクリレートのホモポリマー及びコポリマー、ヒドロキシプロピルメタクリレートのホモポリマー及びコポリマー、ヒドロキシプロピルアクリレートのホモポリマー及びコポリマー、ヒドロキシブチルメタクリレートのホモポリマー及びコポリマー、ヒドロキシブチルアクリレートのホモポリマー及びコポリマー、ポリエチレングリコール類、ヒドロキシプロピレンポリマー類、ポリビニルアルコール類、加水分解度が少なくとも６０質量％、好ましくは少なくとも８０質量％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、ポリビニルピロリドン、アクリルアミドのホモポリマー及びコポリマー、メタクリルアミドのホモポリマー及びコポリマー、Ｎ−メチロールアクリルアミドのホモポリマー及びコポリマー、２−アクリルアミド−２−メチル−１−プロパンスルホン酸のホモポリマー及びコポリマー、２−メタクロイルオキシエチルホスホン酸のホモポリマー及びコポリマー等を挙げることができる。
上記親水性樹脂の添加量は、記録層全固形分中、２０質量％以下が好ましく、１０質量％以下がより好ましい。
【００９１】
また、上記親水性樹脂は印刷機上で未露光部が機上現像できる程度に架橋して用いてもよい。親水性樹脂を架橋するために使用される架橋剤としては、グリオキザール、メラミンホルムアルデヒド樹脂、尿素ホルムアルデヒド樹脂などのアルデヒド類、Ｎ−メチロール尿素やＮ−メチロールメラミン、メチロール化ポリアミド樹脂などのメチロール化合物、ジビニルスルホンやビス（β−ヒドロキシエチルスルホン酸）などの活性ビニル化合物、エピクロルヒドリンやポリエチレングリコ−ルジグリシジルエーテル、ポリアミド、ポリアミン、エピクロロヒドリン付加物、ポリアミドエピクロロヒドリン樹脂などのエポキシ化合物、モノクロル酢酸エステルやチオグリコール酸エステルなどのエステル化合物、ポリアクリル酸やメチルビニルエーテル／マレイン酸共重合物などのポリカルボン酸類、ホウ酸、チタニルスルフェート、Ｃｕ、Ａｌ、Ｓｎ、Ｖ、Ｃｒ塩などの無機系架橋剤、変性ポリアミドポリイミド樹脂などが挙げられる。その他、塩化アンモニウム、シランカップリング剤、チタネートカップリング剤等の架橋触媒を併用できる。
【００９２】
（その他の添加剤）
本発明に係る記録層マトリックス中には、さらに必要に応じて上記以外に種々の化合物を添加してもよい。
＜多官能モノマー＞
耐刷力を一層向上させるために多官能モノマーを添加することができる。この多官能モノマーとしては、マイクロカプセル中に入れられるモノマーとして例示したものを用いることができる。なかでも好ましいモノマーとしては、トリメチロールプロパントリアクリレート、ペンタエリスリトールトリアクリレートなどを挙げることができる。多官能モノマーの添加量は、記録層全固形分中、０．１〜１０質量％が好ましく、０．５〜５．０質量％がより好ましい。
【００９３】
＜熱重合防止剤＞
本発明においては、記録層塗布液の調製中又は保存中においてエチレン性不飽和化合物の不要な熱重合を阻止するために、少量の熱重合防止剤を添加することが望ましい。適当な熱重合防止剤としてはハイドロキノン、ｐ−メトキシフェノール、ジ−ｔ−ブチル−ｐ−クレゾール、ピロガロール、ｔ−ブチルカテコール、ベンゾキノン、４，４′−チオビス（３−メチル−６−ｔ−ブチルフェノール）、２，２′−メチレンビス（４−メチル−６−ｔ−ブチルフェノール）、Ｎ−ニトロソ−Ｎ−フェニルヒドロキシルアミンアルミニウム塩等が挙げられる。熱重合防止剤の添加量は、記録層全固形分中、０．０１〜５質量％が好ましい。
【００９４】
＜無機微粒子＞
本発明に係る記録層マトリックス中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又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。
また、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、マイクロカプセル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、記録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。
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。無機微粒子の記録層への含有量は、記録層の全固形分の２０質量％以下が好ましく、より好ましくは１０質量％以下である。
【００９５】
＜界面活性剤＞
本発明に係る記録層マトリックス中には、記録層の分散安定性、製版及び印刷性能向上や塗布性の向上のため、特開平２−１９５３５６号、特開昭５９−１２１０４４号、特開平４−１３１４９号及び特願２００１−１６９７３１号に記載されているノニオン系、アニオン系、カチオン系、両性又はフッ素系の界面活性剤を添加することができる。これらの界面活性剤の好適な添加量は、記録層全固形分の０．００５〜１質量％である。
【００９６】
＜可塑剤＞
本発明に係る記録層マトリックス中には、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。
【００９７】
〔画像記録層の形成〕
本発明に係る記録層は、必要な上記各成分を溶剤に溶かして塗布液を調製し、塗布される。ここで使用する溶剤としては、エチレンジクロライド、シクロヘキサノン、メチルエチルケトン、メタノール、エタノール、プロパノール、エチレングリコールモノメチルエーテル、１−メトキシ−２−プロパノール、２−メトキシエチルアセテート、１−メトキシ−２−プロピルアセテート、ジメトキシエタン、乳酸メチル、乳酸エチル、Ｎ，Ｎ−ジメチルアセトアミド、Ｎ，Ｎ−ジメチルホルムアミド、テトラメチルウレア、Ｎ−メチルピロリドン、ジメチルスルホキシド、スルホラン、γ−ブチロラクトン、トルエン、水等を挙げることができるが、これに限定されるものではない。これらの溶剤は、単独又は混合して使用される。塗布液の固形分濃度は、好ましくは１〜５０質量％である。
【００９８】
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。
【００９９】
塗布、乾燥後に得られる支持体上の記録層塗布量（固形分）は、用途によって異なるが、一般的に０．５〜５．０ｇ／ｍ^２が好ましい。塗布量が少なくなるにつれて見かけの感度は大になるが、画像記録の機能を果たす記録層の皮膜特性は低下する傾向にある。
【０１００】
〔オーバーコート層〕
本発明に係る平版印刷版原版は、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記録層表面を保護するため、記録層上に、特開２００１−１６２９６１号、特開２００２−１９３１８号に記載の水溶性樹脂を含有するオーバーコート層を設けることができる。
【０１０１】
オーバーコート層に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ス、カルボキシエチルセルローズ、メチルセルロース等）、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又はアミン塩、ポリアクリル酸共重合体、そのアルカリ金属塩又はアミン塩、ポリメタクリル酸、そのアルカリ金属塩又はアミン塩、ビニルアルコール／アクリル酸共重合体及びそのアルカリ金属塩又はアミン塩、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又はアミン塩、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又はアミン塩、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。
【０１０２】
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る。例えば、前記の記録層の説明中に示した（ＩＲ−１）〜（ＩＲ−１１）が好適に用いられる。
【０１０３】
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質量％が好ましく、より好ましくは１〜３質量％である。
【０１０４】
さらに、上記オーバーコート層には、積み重ね保存時のプレート間のくっつきを防止するため、特開２００１−３４１４４８号記載のフッ素原子及びケイ素原子のうちいずれかを有する化合物を含有することができる。
本発明に係るオーバーコート層の厚みは、０．１〜４．０μｍが好ましく、０．１〜１．０μｍ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、親油性物質による記録層の汚染を防止できる。
【０１０５】
〔支持体〕
本発明に係る平版印刷版原版に使用可能な支持体としては、寸度的に安定な板状物であり、例えば、紙、プラスチック（例えば、ポリエチレン、ポリプロピレン、ポリスチレン等）がラミネートされた紙、金属板（例えば、アルミニウム、亜鉛、銅等）、プラスチックフィルム（例えば、二酢酸セルロース、三酢酸セルロース、プロピオン酸セルロース、酪酸セルロース、酢酸酪酸セルロース、硝酸セルロース、ポリエチレンテレフタレート、ポリエチレン、ポリスチレン、ポリプロピレン、ポリカーボネート、ポリビニルアセタール等）、上記の如き金属がラミネート若しくは蒸着された紙又はプラスチックフィルム等が挙げられる。好ましい支持体としてはアルミニウム板が挙げられる。
【０１０６】
該アルミニウム板は、純アルミニウム板及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又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、チタンなどがある。合金中の異元素の含有量は高々１０質量％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、従来から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。
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。
【０１０７】
アルミニウム板を使用するに先立ち、表面の粗面化、陽極酸化などの表面処理をすることが好ましい。表面処理により、親水性の向上及び記録層との接着性の確保が容易になる。
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及び化学的に表面を選択溶解させる方法により行われる。機械的方法としては、ボール研磨法、ブラシ研磨法、ブラスト研磨法、バフ研磨法などの公知の方法を用いることができる。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又は硝酸などの酸を含む電解液中で交流又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。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。
【０１０８】
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など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。
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、クロム酸又はそれらの混酸が用いられる。それらの電解質の濃度は電解質の種類によって適宜決められる。陽極酸化の処理条件は、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質量％溶液、液温は５〜７０℃、電流密度５〜６０Ａ／ｄｍ^２、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／ｍ^２、特に１．５〜４．０ｇ／ｍ^２であることが好ましい。
【０１０９】
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、断熱性などの一層改良のため、必要に応じて、特開２００１−２５３１８１号や特開２００１−３２２３６５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、及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などを適宜選択して行うことができる。
上記親水化処理のための好適な親水性化合物として、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／無機フッ素化合物などが挙げられる。
【０１１０】
本発明に用いる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、親水層を塗布して表面を親水性にすることが望ましい。親水層としては、特開２００１−１９９１７５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、アンチモン及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。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。
【０１１１】
本発明においては、記録層を塗布する前に、必要に応じて、特開２００１−２００１−３２２３６５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ることができる。また、この下塗層には、前記光熱変換剤を含有させることができる。
【０１１２】
このような構成を有する平版印刷版原版を本発明の画像形成方法に適用することで、赤外線を用いた画像露光により、充分な強度を有する画像部が形成されるため、機上現像可能な平版印刷版原版の耐刷性が向上し、高画質の印刷物を多数枚得ることが可能となった。
【０１１３】
【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。
［支持体の作製］
９９．５質量％以上のアルミニウムと、Ｆｅ ０．３０質量％、Ｓｉ ０．１０質量％、Ｔｉ ０．０２質量％、Ｃｕ ０．０１３質量％を含むＪＩＳ Ａ１０５０合金の溶湯に清浄化処理を施し、鋳造した。清浄化処理には、溶湯中の水素などの不要なガスを除去するために脱ガス処理し、セラミックチューブフィルタ処理をおこなった。鋳造法はＤＣ鋳造法で行った。凝固した板厚５００ｍｍの鋳塊を表面から１０ｍｍ面削し、金属間化合物が粗大化してしまわないように５５０℃で１０時間均質化処理を行った。
【０１１４】
次いで、４００℃で熱間圧延し、連続焼鈍炉中で５００℃６０秒中間焼鈍した後、冷間圧延を行って、板圧０．３０ｍｍのアルミニウム圧延板とした。圧延ロールの表面粗さを制御することにより、冷間圧延後の中心線平均表面粗さＲａを０．２μｍに制御した。その後、平面性を向上させるためにテンションレベラーにかけた。
【０１１５】
次に、平版印刷版支持体とするための表面処理を行った。まず、アルミニウム板表面の圧延油を除去するため１０質量％アルミン酸ソーダ水溶液で５０℃３０秒間脱脂処理を行い、３０質量％硫酸水溶液で５０℃３０秒間中和、スマット除去処理を行った。次いで支持体と記録層の密着性を良好にし、かつ非画像部に保水性を与えるため、支持体の表面を粗面化する、いわゆる、砂目立て処理を行った。１質量％の硝酸と０．５質量％の硝酸アルミを含有する水溶液を４５℃に保ち、アルミウェブを水溶液中に流しながら、間接給電セルにより電流密度２０Ａ／ｄｍ^２、デューティー比１：１の交番波形でアノード側電気量２４０Ｃ／ｄｍ^２を与えることで電解砂目立てを行った。その後１０質量％アルミン酸ソーダ水溶液で５０℃３０秒間エッチング処理を行い、３０質量％硫酸水溶液で５０℃３０秒間中和、スマット除去処理を行った。さらに耐摩耗性、耐薬品性、保水性を向上させるために、陽極酸化によって支持体に酸化皮膜を形成させた。電解質として硫酸２０質量％水溶液を３５℃で用い、アルミウェブを電解質中に通搬しながら、間接給電セルにより１４Ａ／ｄｍ^２の直流で電解処理を行うことで２．５ｇ／ｍ^２の陽極酸化皮膜を作成した。
【０１１６】
その後、印刷版非画像部としての親水性を確保するため、シリケート処理を行った。処理は３号珪酸ソーダ１．５質量％水溶液を７０℃に保ちアルミウェブの接触時間が１５秒となるよう通搬し、さらに水洗した。Ｓｉの付着量は１０ｍｇ／ｍ^２であった。以上のように作製した支持体の中心線表面粗さＲａは０．２５μｍであった。
【０１１７】
［カチオン重合性化合物を内包するマイクロカプセルの合成］
油相成分として、ビスフェノールＡのビス（ビニルオキシエチル）エーテル４．５ｇ、トリメチロールプロパンとキシリレンジイソシアナートとの付加体（三井武田ケミカル（株）製タケネートＤ−１１０Ｎ、マイクロカプセル壁材）５ｇ、ミリオネートＭＲ−２００（日本ポリウレタン（株）製芳香族イソシアネートオリゴマー、マイクロカプセル壁材）３．７５ｇ、赤外線吸収色素（本明細書記載のＩＲ−２７）１．５ｇ、パイオニンＡ４１Ｃ（竹本油脂（株）界面活性剤）０．１ｇを酢酸エチル１８．４ｇに溶解した。水相成分としてＰＶＡ２０５（クラレ製ポリビニルアルコール）の４質量％水溶液３７．５ｇを調製した。油相成分及び水相成分を、ホモジナイザーを用い１２０００ｒｐｍで１０分間乳化した。その後テトラエチレンペンタミン（５官能アミン、マイクロカプセル壁架橋剤）０．３８ｇを水２６ｇに溶解したものを添加し、水冷しながら３０分さらに６５℃で３時間攪拌した。このようにして得られたマイクロカプセル液の固形分濃度は２４質量％であり、平均粒径は０．３μｍであった。
【０１１８】
〔実施例１〕
（平版印刷版原版の作製）
上記製造例で得たアルミニウム基板上に、合成例のマイクロカプセルを含む下記の記録層塗布液をバー塗布した後、オーブンで１００℃６０秒の条件で乾燥し、記録層の乾燥塗布量１．０ｇ／ｍ^２の平版印刷版原版を作製した。
＜記録層塗布液＞
・水 ３５．４ｇ
・前記合成例のマイクロカプセル液 ９．０ｇ
・酸発生剤（本明細書に記載のＡＩ−７） ０．２４ｇ
【０１１９】
（露光・印刷および評価）
上記で得られた平版印刷版原版を、図１〜図５に基づいて説明した本発明に係る第１の実施形態の画像露光装置１０又は図６に基づいて説明した第２の実施形態の画像露光装置１００を用いて平版印刷版原版を１６０℃〜１８０℃まで予備加熱し、３０〜１００秒後に、水冷式４０Ｗ赤外線半導体レーザー搭載のＣｒｅｏ社製Ｔｒｅｎｄｓｅｔｔｅｒ３２４４ＶＸにて、出力１７Ｗ、外面ドラム回転数１００ｒｐｍ、解像度２４００ｄｐｉの条件で画像露光を行った。この露光中に、平版印刷版原版の支持体（アルミニウム板）における記録層との接触面、及び画像記録層の表面温度は７０℃以上に保たれていた。これにより、平版印刷版では、ＩＲレーザＬによる露光時に記録層の露光部分から支持体への熱拡散が効果的に抑制される。この結果、記録層と支持体との界面付近でも、マイクロカプセル壁の崩壊又は浸透性向上が効果的に進行すると共に、酸発生剤の分解反応が促進され、また、カチオン重合性化合物の運動性が向上し、重合、硬化反応が効率よく進行するので、強固で耐刷性に優れた画像を形成できた。
【０１２０】
画像露光完了後、平版印刷版原版を現像処理することなく、ハイデルベルグ社製印刷機ＳＯＲ−Ｍのシリンダーに取り付けた。４容量％ＩＦ１０２（富士写真フイルム（株）製）水溶液からなる湿し水と、バリウス墨インキ（大日本インキ化学工業（株）製を用い、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。
【０１２１】
この際、印刷工程の初期段階で非画像部における記録層が除去され、非画像部に汚れのない高画質の印刷物が得られた。その後も印刷を継続し、どれだけの枚数が、非画像部に汚れがなく、画像部が充分なインキ濃度を保って印刷できるかを目視にて測定し、耐刷性の指標とした。枚数が多いほど耐刷性に優れるものと評価する。
その結果、高画質の印刷物が３．５万枚得られ、本発明の方法により画像形成された平版印刷版は、実用性に耐えうる優れた耐刷性を有していることが確認された。
【０１２２】
【発明の効果】
本発明によれば、赤外線を用いた画像露光後に、特段の液体現像処理工程を経ることなく画像形成が可能であり、且つ、耐刷性に優れた平版印刷版を得ることができる画像形成方法、および、この画像形成方法を得ることができる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態に係る画像露光装置の構成を示す側面図である。
【図２】図１に示される画像露光装置における露光ヘッド及びその送り機構の構成を示す斜視図である。
【図３】図１に示される画像露光装置における予備加熱装置の構成を示す斜視図である。
【図４】図３に示される予備加熱装置の側面図である。
【図５】図３に示される予備加熱装置におけるコイルユニットの構成を示す斜視図である。
【図６】本発明の第２の実施形態に係る画像露光装置の構成を示す側面図である。
【符号の説明】
１０、１００ 画像露光装置
１２ 平版印刷版原版
１４ ケーシング
１６ 給版台
１８ 排出トレー
２０ アウタードラム
２２ チャック機構
２６ 露光ヘッド
２８ 露光ヘッドの送り機構
３２ ＬＤ光源装置
３８ 予備加熱装置
４６ 加熱部材
１０２ オートローダー[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method and an image exposure apparatus. More specifically, the present invention relates to an image forming method for a lithographic printing plate capable of making a plate without performing infrared image exposure and special liquid development processing, and the image forming method. The present invention relates to an image exposure apparatus.
[0002]
[Prior art]
The development of laser technology in recent years has been remarkable, and in particular, solid-state lasers and semiconductor lasers (hereinafter referred to as “infrared lasers” where appropriate) that emit infrared rays with a wavelength of 760 nm to 1200 nm can be easily obtained with high output and small size. Became. In particular, in the field of lithographic printing, these infrared lasers are very useful as a recording light source for a CTP (Computer to Plate) system that directly makes a printing plate from digital data such as a computer.
[0003]
Accordingly, many studies have been made on the lithographic printing plate for the CPT system. Among them, as an aim to further streamline the process and solve the waste liquid treatment problem, development-free lithographic printing plate precursors that can be printed on a printing press without being developed after exposure have been studied, and various methods have been studied. Has been proposed.
[0004]
One method of eliminating the development process is to mount the exposed lithographic printing plate precursor on the cylinder of the printing press, and supply dampening water and ink while rotating the cylinder, so that the non-image area of the lithographic printing plate precursor There is a method called on-press development that removes the toner. That is, the lithographic printing plate precursor is exposed and then mounted on a printing machine as it is, and the plate making process is completed in a normal printing process. This eliminates the need for a conventional liquid developing process using developing chemicals, thereby making it possible to rationalize the printing preparation process, eliminate the need for developing waste liquid processing, and the like.
[0005]
As such a lithographic printing plate precursor, there has been proposed a lithographic printing plate precursor containing a cross-linked hydrophilic layer on a substrate and containing a hot-melt material microencapsulated therein (see, for example, Patent Document 1). .) In this printing plate, the microcapsule collapses due to the action of heat generated in the laser exposure area, the lipophilic substance in the microcapsule dissolves, and the hydrophilic layer surface becomes hydrophobic.
[0006]
Other examples using microcapsules that also disintegrate by heat include microcapsules encapsulating a photopolymerizable monomer and a photosensitive resin, and lipophilic components that form an interaction with a three-dimensionally crosslinked hydrophilic layer. A lithographic printing plate precursor using a microcapsule enclosing a liquid crystal has also been proposed (see, for example, Patent Documents 2 and 3).
[0007]
These lithographic printing plate precursors do not require development processing, but when a metal plate such as aluminum having a high thermal conductivity is used as a support, heat to be used for image formation diffuses into the support, and image recording is performed. There was a problem in that the curing of the layer in the vicinity of the contact interface with the support did not proceed sufficiently, and the strength of the image area was insufficient and the printing durability was poor.
[0008]
[Patent Document 1]
International Publication No. 94/23954 Pamphlet
[Patent Document 2]
Japanese Patent Laid-Open No. 62-250454
[Patent Document 3]
Japanese Patent No. 3206297
[0009]
[Problems to be solved by the invention]
An object of the present invention, which was made to solve the above-mentioned conventional problems, was that image formation was possible without passing through a special liquid development processing step after image exposure using infrared rays, and excellent printing durability. An object is to provide an image forming method capable of obtaining a lithographic printing plate and an image exposure apparatus suitable for the image forming method.
[0010]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have achieved the above object by heating the entire lithographic printing plate precursor before image exposure to the lithographic printing plate precursor provided with a recording layer containing a specific microcapsule. And the present invention has been solved.
[0011]
That is, the image forming method of the present invention according to claim 1 includes an image recording layer containing a microcapsule enclosing a cationically polymerizable compound, an acid generator, and a photothermal conversion agent on a support. An image forming method for forming an image on a lithographic printing plate precursor, comprising a preheating step of heating the lithographic printing plate precursor to a predetermined preheating temperature, and an infrared irradiation of the lithographic printing plate precursor heated to the preheating temperature. And an image exposure step of forming an image on the image recording layer of the lithographic printing plate precursor.
[0012]
The preheating temperature is preferably a temperature range in which the acid generator in the system is activated and the microcapsule wall material is not destroyed, and is generally in the range of 50 ° C to 230 ° C. More preferably, it is the range of 50 to 200 degreeC.
[0013]
The image exposure apparatus of the present invention according to claim 3 is an image exposure apparatus used in the image forming method, wherein a lithographic printing plate precursor can be mounted, and the mounted lithographic printing plate precursor is held. Preheating that heats the holding member and the lithographic printing plate precursor to be mounted on the holding member to the preheating temperature by heat energy or electromagnetic energy provided from a heat supply unit extending linearly or spreading in a planar shape And exposure means for forming an image on an image recording layer of the lithographic printing plate precursor by exposing the lithographic printing plate precursor held by the holding member with infrared rays.
[0014]
The lithographic printing plate precursor according to the invention is characterized in that the recording layer contains a microcapsule encapsulating a cationically polymerizable compound, an acid generator, and a photothermal conversion agent. The image forming mechanism of such a lithographic printing plate precursor is as follows. The energy of infrared light in image exposure is converted into thermal energy by the photothermal conversion agent, and the heat causes the microcapsule wall to collapse or become permeable, and the encapsulated cationically polymerizable compound is removed from the microcapsule. Is released (exuded). Similarly, the acid generated from the acid generator by the energy of image exposure serves as a polymerization initiator for the cationic polymerizable compound released (exuded) out of the microcapsule, and initiates or advances the polymerization reaction. This is a mechanism in which a hydrophobic region, that is, an image portion is formed. However, the energy used for image exposure alone is not sufficient to break the microcapsules and further activate the acid generator, and as described above, near the interface between the recording layer and the support. , Since thermal diffusion (heat absorption) from the recording layer to the support occurs, unreacted microcapsules and unreacted acid generators remain, leading to the formation of a strong and excellent printing durability image. It was.
[0015]
In the image forming method of the present invention, before the lithographic printing plate precursor is subjected to image exposure with infrared rays, at least the entire region where the image is formed on the lithographic printing plate precursor is temperature energy (usually about 270 ° C.). (Hereinafter, referred to as “preliminary heating” as appropriate). The preheating temperature is preferably about 50 ° C. to 230 ° C., and by this heating, the support itself of the lithographic printing plate precursor is preheated, and thermal diffusion to the support during subsequent image exposure can be suppressed. . For this reason, most of the energy from image exposure is efficiently used for image formation, that is, for the purpose of decomposing the acid generator and breaking the microcapsule, and the polymerizable compound released (exuded) from the microcapsule and the acid generation The acid generated from the agent initiates the polymerization reaction. At this time, the image recording layer is also preheated at the same time as the support, and the mobility of the reaction material is increased by heat in the reaction system, so that the polymerization reaction proceeds efficiently, resulting in strong and durable printing. It is considered that an excellent image can be formed. Further, as a more preferable aspect, by setting the preheating temperature within a temperature range in which the acid generator can be activated, for example, about 140 to 200 ° C., in addition to the above effects, the preheating is sufficiently sufficient from the acid generator in advance. The effect that a sufficient amount of acid can be generated is obtained. In this case, after that, by performing image exposure in a state in which the acid that is the starting species is sufficiently present in the system, the cationically polymerizable compound exuded from the microcapsules that have become permeable by the image exposure is sufficiently present in the vicinity. Since the polymerization reaction is immediately caused and progressed by the amount of acid, it is considered that the reaction proceeds more efficiently and the effect of the present invention becomes remarkable.
[0016]
Further, in the image exposure apparatus of the present invention, the preheating means extends the lithographic printing plate precursor to be attached to the holding member where the exposure to the lithographic printing plate precursor is performed, into a line extending in a line shape or a line extending in a planar shape. After heating to a predetermined preheating temperature by heat energy or electromagnetic energy supplied from a heat supply unit, the exposure means exposes the lithographic printing plate precursor held by the holding member with infrared rays to record an image of the lithographic printing plate precursor Form an image on the layer. Thus, after one or both of the image recording layer and the support in the lithographic printing plate precursor are heated to a predetermined preheating temperature, the lithographic printing plate precursor can be exposed with infrared rays. Most of these are used for the purpose of breaking the microcapsules, and the polymerizable compound released (exuded) without leaving the microcapsules and a sufficient amount of acid can efficiently initiate or advance the polymerization reaction.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
[Configuration of image exposure apparatus]
First, an image exposure apparatus in which an image forming method according to the present invention is preferably implemented will be described with reference to the drawings.
[0018]
(First embodiment)
1 to 5 show an image exposure apparatus according to a first embodiment of the present invention. The image exposure apparatus 10 scans and exposes a lithographic printing plate precursor 12 with an infrared laser (hereinafter referred to as “IR laser L”) modulated based on digital image information, and the lithographic printing plate precursor 12 has digital image information. An image (latent image) corresponding to is formed. Here, the lithographic printing plate precursor 12 is a so-called non-processed printing plate that does not require special development processing, and is formed on a support made of aluminum or an aluminum alloy and on this support. An image recording layer is provided, and this image recording layer (hereinafter simply referred to as “recording layer”) contains at least microcapsules enclosing a cationically polymerizable compound, an acid generator, and a photothermal conversion agent.
[0019]
The acid generator and the photothermal conversion agent may be added to at least one of the inside of the microcapsule and the outside of the microcapsule, that is, in the recording layer matrix. The generator is preferably added to the recording layer matrix. Moreover, it is preferable from a viewpoint of a sensitivity that a photothermal conversion agent is added in a microcapsule.
[0020]
As shown in FIG. 1, the image exposure apparatus 10 is provided with a casing 14 as an outer shell portion of the apparatus. The casing 14 has a side plate portion on one side along the width direction of the apparatus (direction of arrow W). A plate feeding table 16 for mounting a bundle of lithographic printing plate precursors 12 is attached to a platen, and a discharge tray 18 for discharging the exposed lithographic printing plate precursor 12 is provided on the upper side of the plate feeding table 16. It has been. In the casing 14, a cylindrical outer drum 20 on which one lithographic printing plate precursor 12 can be attached and detached is rotatably arranged. On the outer peripheral side of the outer drum 20, a chuck mechanism 22 for chucking the front end portion and the rear end portion of the planographic printing plate precursor 12 on the outer drum 20 is provided, and the planographic printing plate precursor 12 is attached to the outer drum 20. A guide roller 24 for winding on the outer peripheral surface is installed.
[0021]
An exposure head 26 facing the outer drum 20 and a feed mechanism 28 that supports the exposure head 26 so as to be movable along the sub-scanning direction are disposed in the casing 14. The exposure head 26 and the feed mechanism 28 scan and expose the lithographic printing plate precursor 12 mounted on the outer drum 20 by the IR laser L modulated based on the digital image information, and convert the lithographic printing plate precursor 12 into digital image information. This is for forming a corresponding image. In the casing 14, a light source box 30 is disposed on the lower side of the outer drum 20, and an LD light source device 32 (see FIG. 2) for supplying the IR laser L to the exposure head 26 is disposed in the light source box 30. ) Is stored.
[0022]
As shown in FIG. 1, the image exposure apparatus 10 is provided with a feeding mechanism 34 for transporting the lithographic printing plate precursor 12 loaded on the plate feeding table 16 in the casing 14 to the outer drum 20. Yes. The feeding mechanism 34 includes a plurality of conveying rollers 35 and a plate-shaped guide member 36 arranged along the feeding path of the planographic printing plate precursor 12. Further, the feeding mechanism 34 separates one lithographic printing plate precursor 12 from a bundle of lithographic printing plate precursors 12 stacked on the plate feeding table 16 at the end on the plate feeding table 16 side. A separation mechanism (not shown) for supplying the lithographic printing plate precursor 12 to the feeding path is provided, and a preheating device 38 for heating (preheating) the entire lithographic printing plate precursor 12 in the middle of the feeding path. It is attached.
[0023]
The preheating device 38 heats the lithographic printing plate precursor 12 by magnetic induction heating. As shown in FIGS. 3 and 4, an endless heat resistant film 40 and an inner peripheral side of the heat resistant film 40 are provided. A film guide 42 disposed and a pressure roller 44 disposed below the heat resistant film 40 are provided. The film guide 42 is formed in a substantially C shape whose cross-sectional shape is open upward, and the dimension along the axial direction is longer than the width of the planographic printing plate precursor 12. A plate-shaped heating member 46 and a coil unit 48 made of magnetic metal are embedded in the lower end portion of the film guide 42. The widths of the coil unit 48 and the heating member 46 are wider than the width of the planographic printing plate precursor 12.
[0024]
Here, the lower surface portion of the heating member 46 forms a part of the outer peripheral surface of the film guide 42, and the coil unit 48 is in close contact with the upper surface portion of the heating member 46. Further, the inner peripheral length of the heat resistant film 40 is set to have a margin with respect to the outer peripheral length of the film guide 42, whereby the heat resistant film 40 does not generate tension on the outer peripheral side of the film guide 42. It fits loosely.
[0025]
The pressure roller 44 is provided with a rod-shaped cored bar 50 at its axial center and a thick cylindrical elastic layer 52 fixed on the outer peripheral surface of the cored bar 50. Here, the elastic layer 52 is formed of a rubber material having good releasability such as silicon rubber. The pressure roller 44 rotates at a linear speed equal to the conveying speed of the lithographic printing plate precursor 12 by torque from a drive motor (not shown) connected to the core metal 50, and is heated via the heat resistant film 40. It is supported so as to be pressed against. A pressure contact portion N (see FIG. 4) formed between the pressure roller 44 and the heating member 46 is located on the feeding path of the planographic printing plate precursor 12. As a result, the lithographic printing plate precursor 12 passes through the press contact portion N while being pressed and clamped while being conveyed from the plate supply table 16 to the outer drum 20, and is heated by the preheating device 38 at the press contact portion N. (Preheating). At this time, the heat resistant film 40 circulates and moves along the outer peripheral surface of the film guide 42 by the frictional force with the planographic printing plate precursor 12.
[0026]
As shown in FIG. 5, the coil unit 48 includes a plurality of excitation coils 54 arranged linearly along the width direction of the planographic printing plate precursor 12, and these excitation coils 54 are connected in series. The excitation coils 54 at both ends thereof are respectively connected to output terminals for high-frequency current in a high-frequency converter (not shown). Thus, when a high-frequency current output from the high-frequency converter is applied to the excitation coils 54, a high-frequency magnetic field is generated from each excitation coil 54, and this high-frequency magnetic field acts on the heating member 46. As a result, the heating member 46 made of magnetic metal is induction-heated to generate a heat amount corresponding to the strength of the high-frequency magnetic field, the frequency of the high-frequency current, and the like. Therefore, the amount of heat applied from the heating member 46 to the planographic printing plate precursor 12 is controlled by changing the waveform (switching duty, frequency, etc.) of the high frequency current applied to the exciting coil 54 by the high frequency converter and controlling the supply power. Control becomes possible.
[0027]
As shown in FIG. 1, the image exposure apparatus 10 is provided with a temperature sensor 56 immediately after the preheating device 38 along the feeding path, and this temperature sensor 56 has passed through the preheating device 38. The surface temperature of the lithographic printing plate precursor 12 is detected, and a detection signal is output to a heating control unit (not shown) of the apparatus. The heating controller heats the temperature of the lithographic printing plate precursor 12 that has passed through the pressure contact portion N to a preset preheating temperature by performing feedback control of the high-frequency converter based on a detection signal from the temperature sensor 56. In the preheating device 38, the lower surface portion of the heating member 46 is formed in a planar shape. As a result, the heating member 46 comes into pressure contact with the lithographic printing plate precursor 12 passing through the pressure contact portion N in a surface contact state. However, the lower surface portion of the heating member 46 has a curved surface with respect to the lithographic printing plate precursor 12. Thus, the contact may be made in a substantially line contact state.
[0028]
In the image exposure apparatus 10, when the planographic printing plate precursor 12 is conveyed to the vicinity of the upper end of the outer drum 20 by the feeding mechanism 34, the tip of the planographic printing plate precursor 12 is chucked on the outer drum 20 by the chuck mechanism 22. At the same time, the outer drum 20 starts to rotate in a predetermined forward rotation direction (the direction of arrow R1 in FIG. 1). As a result, the lithographic printing plate precursor 12 whose tip is restrained on the outer drum 20 by the tip clamp is wound while being pressed onto the outer peripheral surface of the outer drum 20 by the guide roller 24.
[0029]
In the image exposure apparatus 10, when the planographic printing plate precursor 12 is wound around the outer drum 20 to the rear end portion, the rear end portion of the planographic printing plate precursor 12 is chucked onto the outer drum 20 by the chuck mechanism 22. Thereby, the entire planographic printing plate precursor 12 is brought into close contact with the outer peripheral surface of the outer drum 20, and the mounting of the planographic printing plate precursor 12 to the outer drum 20 is completed. In the image exposure apparatus 10, the IR laser L emitted from the exposure head 26 while moving the exposure head 26 in the sub-scanning direction by the feed mechanism 28 with the lithographic printing plate precursor 12 mounted on the outer drum 20. Is irradiated onto the lithographic printing plate precursor 12 to perform sub-scanning exposure on the lithographic printing plate precursor 12. Further, the image exposure apparatus 10 can perform main scanning on the lithographic printing plate precursor 12 by rotating the outer drum 20 by a rotation amount corresponding to the main scanning pitch in the forward rotation direction in synchronization with the completion of one sub-scan. It has become.
[0030]
As shown in FIG. 2, the exposure head 26 includes a lens unit 58 that includes a plurality of lenses and forms an imaging optical system, a pair of support plates that sandwich the tips of a plurality of optical fibers 70, and light. A fiber holder 60 made of a transparent protective plate or the like for protecting the front end surface of the fiber 70 is mounted. Here, the IR lasers L respectively emitted from the plurality of optical fibers 70 enter the lens unit 58 and are combined by the lens unit 58 and imaged on the lithographic printing plate precursor 12 mounted on the outer drum 20. Then, a beam spot having a predetermined shape is formed.
[0031]
Further, the feeding mechanism 28 includes a pair of guide rails 62 that support the exposure head 26 slidably along the sub-scanning direction (the direction of arrow S in FIG. 2) and a screw shaft 66 connected to the motor unit 64. . A block-shaped carrier 68 is fixed to the lower surface portion of the exposure head 26, and a screw shaft 66 is screwed into a female screw hole formed in the carrier 68. As a result, when the screw shaft 66 is rotated by the motor unit 64, the exposure head 26 adjusts the rotation amount of the screw shaft 66 in the direction corresponding to the rotation direction of the screw shaft 66 (forward direction or reverse direction) along the sub-scanning direction. Move the corresponding distance. In the image exposure apparatus 10 of the present embodiment, sub-scanning with respect to the planographic printing plate precursor 12 is performed only when the exposure head 26 moves forward, but sub-scanning (reciprocal scanning) is performed when the exposure head 26 moves forward and backward. Anyway.
[0032]
As shown in FIG. 2, the other ends of the plurality of optical fibers 70 are respectively connected to the plurality of semiconductor lasers 72 in the LD light source device 32. The semiconductor laser 72 in the LD light source device 32 is fixed on a plate-shaped heat sink 74. A connector array 76 is provided in the middle of the optical fiber 70, and the optical fiber 70 can be brought into contact with and separated from the fiber holder 60 side and the semiconductor laser 72 side through the connector array 76. . Thereby, for example, when the semiconductor laser LD fails, the failed semiconductor laser 72 can be easily replaced without disassembling the fiber holder 60 or the like.
[0033]
In the feed mechanism 28, a tube-shaped cable bear 78 and a hook-shaped bear guide 80 are arranged below the guide rail 62 so as to extend in the sub-scanning direction. The cable bear 78 has a structure in which a large number of link pieces 82 divided in the longitudinal direction are linked in series, and is flexible in the vertical direction perpendicular to the sub-scanning direction. A portion (front end side) of the optical fiber 70 on the exposure head 26 side is inserted into the cable bear 78. Further, the bear guide 80 restricts the movement of the cable bear 78 in the front-rear direction while supporting the cable bear 78 from below. Thereby, when the exposure head 26 moves in the sub-scanning direction, the distal end side of the optical fiber 70 that moves together with the exposure head 26 is protected by the cable bear 78, and damage to the optical fiber 70 is prevented.
[0034]
As shown in FIG. 1, the image exposure apparatus 10 is provided with a carry-out mechanism 84 for carrying the lithographic printing plate precursor 12 detached from the outer drum 20 to the discharge tray 18 in the casing 14. The unloading mechanism 84 includes a plurality of conveying rollers 86 and a plate-shaped guide member 88 arranged along the unloading path of the planographic printing plate precursor 12.
[0035]
In the image exposure apparatus 10, after the exposure (image formation) to the lithographic printing plate precursor 12 mounted on the outer drum 20 is completed, the outer drum 20 is rotated in the reverse direction (in the direction of arrow R <b> 2 in FIG. 1) and the chuck mechanism 22. The rear end and the front end of the planographic printing plate precursor 12 are sequentially released from the outer drum 20. In conjunction with this, the carry-out mechanism 84 rotates the transport roller 86 to start transporting the planographic printing plate precursor 12 sent from the outer drum 20 to the entrance of the discharge path to the discharge tray 18. The printing plate precursor 12 is discharged onto the discharge tray 18.
[0036]
(Second Embodiment)
FIG. 6 shows an image exposure apparatus according to the second embodiment of the present invention. In the image exposure apparatus 100 according to the second embodiment, the same reference numerals are given to the same parts as those of the image exposure apparatus 10 according to the first embodiment, and the description thereof is omitted.
[0037]
Similar to the image exposure apparatus 10 of the first embodiment, the image exposure apparatus 100 scans and exposes the lithographic printing plate precursor 12 with an IR laser L that is modulated based on digital image information. An image corresponding to digital image information is formed. The difference between the image exposure apparatus 100 and the image exposure apparatus 10 is that, as shown in FIG. 6, the plate supply table 16 on which a bundle of planographic printing plate precursors 12 is loaded is omitted. Instead, the autoloader 102 is added as an optional unit, and the preheating device is transferred from the casing 14 to the autoloader 102.
[0038]
The autoloader 102 is for supplying the planographic printing plate precursor 12 to the feeding mechanism 34 in accordance with control from a control unit (not shown) of the image exposure apparatus 100 or a preset supply schedule. The autoloader 102 includes a loading unit 104 that can load a large number of lithographic printing plate precursors 12 and a separation unit that separates one lithographic printing plate precursor 12 from a bundle of lithographic printing plate precursors 12 loaded in the loading unit 104. A lithographic printing plate precursor 12 separated by a mechanism (not shown) and a separation mechanism is conveyed along a predetermined conveyance path, and is supplied to a feeding mechanism 34 on the image exposure apparatus 100 main body side of the image exposure apparatus 100. A transport mechanism 106 is provided.
[0039]
Here, the transport mechanism 106 includes a transport roller 108, a guide member 110, and the like arranged along the transport path. The planographic printing plate precursor 12 is input from the loading unit 104 to the feed path of the image exposure apparatus 100. It is transported to a part at a predetermined transport speed. Further, the autoloader 102 is provided with a casing 112 as an outer shell portion, and a bridge-shaped connecting portion 114 that connects the casing 112 to the casing 14 of the image exposure apparatus 100. In the autoloader 102, the lithographic printing plate precursor 12 conveyed by the conveyance mechanism 106 passes through the connecting portion 114 and is conveyed into the casing 14 of the image exposure apparatus 100.
[0040]
The autoloader 102 is provided with a preheating device 38 for preheating the lithographic printing plate precursor 12 in the connecting portion 114, and this preheating device 38 is supplied to the feeding mechanism 34 by the transport mechanism 106. The planographic printing plate precursor 12 is heated to a predetermined preheating temperature. The preheating device 38 of the second embodiment has a structure that is basically the same as that of the first embodiment. However, in the image exposure apparatus 100, since the distance from the preheating device 38 to the outer drum 20 becomes long and the conveyance time increases, it is necessary to set the preheating temperature higher than the preheating temperature of the image exposure apparatus 10. In some cases. Therefore, the design specifications of the heat generation amount of the preheating device 38 may be changed according to the preheating temperature level.
[0041]
In the image exposure apparatus 100 according to the second embodiment configured as described above, the preheating device 38 is disposed in the autoloader 102 that is an optional unit. This is the same as a conventional image exposure apparatus that does not include the preheating device 38. Therefore, according to the image exposure apparatus 100, the lithographic printing plate precursor 12 can be preheated only by attaching the autoloader 102 to the main body of the conventional image exposure apparatus. The development cost and development time of the exposure apparatus can be greatly reduced, and the image exposure apparatus already delivered to the user can be remodeled to be capable of preheating only by adding the autoloader 102 and a simple setting change.
[0042]
The preheating device 38 of the image exposure apparatuses 10 and 100 according to the present invention heats the heating member 46 to a high temperature state by magnetic induction, and heats the lithographic printing plate precursor 12 by heat transfer from the heating member 46 (indirectly). In this case, the high frequency magnetic field from the coil unit 48 is applied to the support (aluminum plate) in the lithographic printing plate precursor 12 without passing through the heating member 46, so that the support is induction heated (direct heating). You may make it do.
[0043]
Further, as the preheating device 38, in addition to a device using magnetic induction heating, an air flow (hot air) heated by a heater such as a halogen heater or a ceramic heater is blown onto the lithographic printing plate precursor 12 to prepare a lithographic printing plate precursor. What is heated, what is irradiated with an electromagnetic wave of a predetermined wavelength generated by a magnetron to the image recording layer of the lithographic printing plate precursor 12 and resonates and heats a substance such as water in the image recording layer (electromagnetic wave heating), infrared lamp It is also possible to use the one that heats the lithographic printing plate precursor by irradiating the lithographic printing plate precursor.
[0044]
When performing the electromagnetic wave heating, for the purpose of effectively absorbing the electromagnetic wave and converting it to heat energy, it is preferable to include a component that can resonate with the electromagnetic wave and generate heat in the recording layer component. For example, when using a generally used 240 Hz electromagnetic wave, water corresponds to that component, and therefore, by containing a compound that retains water such as a hydrophilic resin or a water-soluble compound in the recording layer component, Water retention in the recording layer can be improved and efficient heat generation can be generated. Examples of the hydrophilic resin used herein include those described in the section of the hydrophilic resin described later in this specification. Among them, polysaccharides such as arabic rubber, soya rubber, hydroxypropyl cellulose, hydroxymethyl cellulose, polyacrylic acid, High molecular compounds having a hydroxyl group in the molecule such as sodium polyacrylate, hydroxypropyl acrylate and polyvinyl alcohol, and low molecular weight compounds such as sorbitol and glycerin are preferred from the viewpoint of improving the water retention of the recording layer.
[0045]
The lithographic printing plate precursor thus image-exposed and discharged from the image-exposure apparatus is then mounted on a printing machine without performing special development with a liquid developer, and using ink and fountain solution. Printing can be performed by a normal procedure. That is, the unexposed portion of the lithographic printing plate precursor after exposure is easily removed by an aqueous component contained in the fountain solution or an oily component such as ink in the initial stage of the printing process. Is exposed, and dampening water adheres to it to form a non-image area, and the hydrophobic area cured by exposure forms an ink-receptive image area.
These lithographic printing plate precursors can also be used for printing after being subjected to a development treatment using water or an appropriate aqueous solution as a developer.
[0046]
The lithographic printing plate precursor imaged by the method of the present invention has a problem in a so-called on-press development type lithographic printing plate because the image area is sufficiently cured by the function of the preheating step and the strength of the image area is excellent. The high printing durability that has been achieved has been realized, and it has become possible to obtain a large number of good printed matter.
The method of the present invention can be applied not only to scanning exposure based on digital data using an infrared laser, but also to image exposure based on analog data and image exposure using a lith film as long as an infrared beam is used. Needless to say.
[0047]
(Configuration of lithographic printing plate precursor)
Next, the configuration of a lithographic printing plate precursor that can be suitably applied to the method of the present invention and that can form an image without requiring a liquid development processing step will be described in detail.
[0048]
The lithographic printing plate precursor according to the present invention comprises an image recording layer containing a microcapsule encapsulating a cationically polymerizable compound, an acid generator, and a photothermal conversion agent on a support.
[0049]
(Image recording layer)
(Microcapsules encapsulating cationically polymerizable compounds)
The cationically polymerizable compound used in the present invention is not particularly limited as long as it is a compound having a cationically polymerizable group in the molecule. Among them, a compound having a vinyloxy group or an epoxy group is preferably used.
Examples of the cationically polymerizable compound having a vinyloxy group suitable for the present invention include compounds described in JP-A-2002-29162.
[0050]
Specifically, tetramethylene glycol divinyl ether, trimethylolpropane trivinyl ether, tetraethylene glycol divinyl ether, pentaerythritol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, 1,4-bis {2- (vinyloxy) ethyloxy } Benzene, 1,2-bis {2- (vinyloxy) ethyloxy} benzene, 1,3-bis {2- (vinyloxy) ethyloxy} benzene, 1,3,5-tris {2- (vinyloxy) ethyloxy} benzene, 4,4′-bis {2- (vinyloxy) ethyloxy} biphenyl, 4,4′-bis {2- (vinyloxy) ethyloxy} diphenyl ether, 4,4′-bis {2- (vinyloxy) ethyl Xyl} diphenylmethane, 1,4-bis {2- (vinyloxy) ethyloxy} naphthalene, 2,5-bis {2- (vinyloxy) ethyloxy} furan, 2,5-bis {2- (vinyloxy) ethyloxy} thiophene, , 5-bis {2- (vinyloxy) ethyloxy} imidazole, 2,2-bis [4- {2- (vinyloxy) ethyloxy} phenyl] propane, bis (vinyloxyethyl) ether of bisphenol A, 2,2-bis {4- (vinyloxymethyloxy) phenyl} propane, 2,2-bis {4- (vinyloxy) phenyl} propane and the like, among others, 2,2-bis [4- {2- (vinyloxy) ethyloxy} Phenyl] propane, bis (vinyloxyethyl) ether of bisphenol A, 2, - bis {4- (vinyloxymethyl) phenyl} propane, 2,2-bis {4- (vinyloxy) phenyl} propane are especially preferred. The present invention is not limited to these.
[0051]
As the cationically polymerizable compound having an epoxy group suitable for the present invention, a compound having two or more epoxy groups is preferable, and a glycidyl ether compound obtained by a reaction of a polyhydric alcohol or a polyhydric phenol with epichlorohydrin or the like. Examples thereof include a prepolymer, and a polymer or copolymer of glycidyl acrylate or glycidyl methacrylate.
[0052]
Specifically, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl ether of hydrogenated bisphenol A, hydroquinone diglycidyl Ether, resorcinol diglycidyl ether, diglycidyl ether or epichlorohydrin polyadduct of bisphenol A, diglycidyl ether or epichlorohydrin polyadduct of bisphenol F, diglycidyl ether or epichlorohydride of halogenated bisphenol A Phosphorus polyadduct, diglycidyl ether of biphenyl type bisphenol or epichlorohydrin polyadduct, novolac resin Examples include lysidyl etherified compounds, methyl methacrylate / glycidyl methacrylate copolymer, ethyl methacrylate / glycidyl methacrylate methacrylate, and the like. Among them, diglycidyl ether or epichlorohydrin polyadduct of bisphenol A Diglycidyl ether or epichlorohydrin polyadduct of halogenated bisphenol A, diglycidyl ether or epichlorohydrin polyadduct of biphenyl type bisphenol are particularly preferred. The present invention is not limited to these.
[0053]
Commercially available products of the above compounds include, for example, Epicoat 1001 (molecular weight: about 900, epoxy equivalent: 450 to 500), Epicoat 1002 (molecular weight: about 1600, epoxy equivalent: 600 to 700), Epicoat 1004 (about) manufactured by Japan Epoxy Resin Co., Ltd. 1060, epoxy equivalent 875-975), Epicoat 1007 (molecular weight about 2900, epoxy equivalent 2000), Epicoat 1009 (molecular weight about 3750, epoxy equivalent 3000), Epicoat 1010 (molecular weight about 5500, epoxy equivalent 4000), Epicoat 1100L (epoxy equivalent) 4000), Epikote YX31575 (epoxy equivalent 1200), Sumitomo Chemical Co., Ltd. Sumiepoxy ESCN-195XHN, ESCN-195XL, ESCN-195XF, and the like.
[0054]
Furthermore, the inclusion of the microcapsule according to the present invention may contain a thermopolymerizable compound having the following heat-reactive group in addition to the cationic polymerizable compound.
Examples of the thermally polymerizable group include an isocyanate group that undergoes an addition reaction, a block thereof, and a functional group having an active hydrogen atom that is a reaction partner with a cationically polymerizable group such as the epoxy group or vinyloxy group (for example, Amino group, hydroxy group, carboxy group, etc.),
A carboxy group that performs a condensation reaction, and a hydroxy group and an amino group that are reaction partners thereof,
Examples thereof include an acid anhydride that undergoes a ring-opening addition reaction, and an amino group and a hydroxy group that are reaction partners thereof.
[0055]
Suitable compounds having an isocyanate group for the present invention include tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, xylylene diisocyanate, naphthalene diisocyanate, cyclohexanephenylene diisocyanate, isophorone diester. Examples thereof include isocyanate, hexamethylene diisocyanate, cyclohexyl diisocyanate, and compounds obtained by blocking these with alcohol or amine.
[0056]
Examples of the compound having an amino group suitable for the present invention include ethylenediamine, diethylenetriamine, triethylenetetramine, hexamethylenediamine, propylenediamine, and polyethyleneimine.
Examples of the compound having a hydroxy group suitable for the present invention include compounds having a terminal methylol group, polyhydric alcohols such as pentaerythritol, and bisphenol / polyphenols.
[0057]
Examples of the compound having a carboxy group suitable for the present invention include aromatic polyvalent carboxylic acids such as pyromellitic acid, trimellitic acid, and phthalic acid, and aliphatic polyvalent carboxylic acids such as adipic acid.
Suitable acid anhydrides for the present invention include pyromellitic acid anhydride and benzophenone tetracarboxylic acid anhydride.
[0058]
In the image recording layer according to the present invention, it is necessary to add a photothermal conversion agent and an acid generator to at least one of the microcapsule and the recording layer matrix. These components are added to the microcapsule. In that case, it is made to include by dissolving or dispersing in the same solvent as the above inclusion. Further, usable photothermal conversion agents and acid generators will be described later.
[0059]
As a method for microencapsulating each of the above components, known methods 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, interfacial polymerization method, US Pat. No. 3,418,250, US Pat. No. 3,660,304, method of polymer precipitation, US Pat. No. 3,796,669, method using isocyanate polyol wall material, US Pat. US Pat. No. 3,914,511 shows a method using an isocyanate wall material, US Pat. Nos. 4001140, 4087376, and 4089802 use a urea-formaldehyde system or a urea formaldehyde-resorcinol wall forming material, A method using a wall material such as melamine-formaldehyde resin and hydroxycellulose, as shown in U.S. Pat. No. 4,025,445, an in situ method by monomer polymerization as shown in JP-B-36-9163 and 51-9079, British Patent 930422, US Pat. No. 3,111,407 And the like, but are not limited thereto, such as the spray drying method found in British Patent Nos. 952807 and 967074.
[0060]
A preferable microcapsule wall material used in the present invention has properties that it can swell in a coating solvent and can form a three-dimensional crosslink. 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. Further, a compound having a thermally reactive group may be introduced into the microcapsule wall.
[0061]
The average particle diameter of the obtained microcapsules is preferably 0.01 to 3.0 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.
[0062]
In such a microcapsule, when the capsule wall material is disintegrated by heat or becomes permeable, the encapsulated cationically polymerizable compound is released into the system, and a curing reaction occurs and proceeds. When the preheating temperature in the heating process reaches a temperature at which the capsule wall material becomes permeable, an undesired curing reaction occurs in the non-image area, and the non-image area is likely to be stained. It is preferable that the upper limit is a temperature lower than the temperature at which it becomes permeable, preferably 30 ° C. below the temperature at which the capsule wall material becomes permeable. The temperature at which the capsule wall material becomes permeable varies depending on the material forming the capsule wall material and the thickness of the wall material.For example, when an adduct of trimethylolpropane and xylylene diisocyanate is used as a microcapsule wall material, When the reaction product of trimethylolpropane and xylylene diisocyanate, Millionate MR-200 (aromatic isocyanate made by Nippon Polyurethane) and tetraethylenepentamine is used as the wall material It is about 278 degreeC.
[0063]
In addition, such microcapsules may be combined with each other by heat, or may not be combined. In short, the microcapsule inclusions ooze out from the surface of the microcapsule or outside the microcapsule by image exposure and cause a chemical reaction with the acid generated from the acid generator described later, or the acid penetrates into the microcapsule wall. However, a chemical reaction may be caused. Furthermore, you may react with the below-mentioned hydrophilic resin or low molecular compound added to a recording layer as an arbitrary component. In addition, the microcapsules may be reacted with each other by providing the microcapsules with different functional groups that are thermally reacted with each other. Therefore, it is preferable for image formation that the microcapsules are melted and united by heat, but it is not essential.
[0064]
The amount of such microcapsules added to the recording layer is preferably 50% by mass or more, and more preferably 70 to 98% by mass in terms of solid content in terms of solid content. Within this range, a good image can be formed and good printing durability can be obtained.
[0065]
In the recording layer containing microcapsules, a solvent capable of dissolving the inclusions of the microcapsules and swelling the wall material can be added to the microcapsule dispersion medium. By adding such a solvent, the diffusion of the microcapsule inclusions outside the capsule is promoted during image exposure.
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.
[0066]
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, Examples include N-dimethylformamide and N, N-dimethylacetamide, but the present invention is not limited thereto. Two or more of these solvents may be used in combination. A solvent that does not dissolve alone in the microcapsule dispersion medium but dissolves by mixing the above-mentioned solvents can also be used.
The amount of such a solvent added depends on the combination of materials, but usually 5 to 95% by mass of the recording layer coating solution is effective, and a preferable range is 10 to 90% by mass, and a more preferable range is 15 It is -85 mass%.
[0067]
(Photothermal conversion agent)
In the recording layer according to the present invention, it is necessary to add a photothermal conversion agent having a function of absorbing light energy and converting it into heat. In this case, a photothermal conversion agent may be added to at least one of the inside of the microcapsule and the recording layer matrix. In the present invention, from the viewpoint that infrared energy can efficiently contribute to image formability, It is preferable to add.
[0068]
The photothermal conversion agent may be any substance that absorbs infrared rays, particularly near infrared rays (wavelength 700 to 1200 nm), and various known pigments, dyes or pigments, and metal fine particles can be used.
For example, the pigments, dyes or dyes described in JP-A-2001-301350, JP-A-2002-137562, Journal of the Japan Printing Association, Vol. 38, pages 35-40 (2001) “New imaging materials, 2. Near infrared absorbing dyes” Dyes and fine metal particles are preferably used. As these pigments and metal fine particles, those subjected to a known surface treatment can be used as necessary.
[0069]
More specifically, as dyes or pigments, U.S. Pat. Nos. 4,756,993 and 4,973,572, JP-A-10-268512, JP-A-11-235883, JP-B-5-13514, JP-A-5-19702, and JP-A-2001-2001. Examples thereof include cyanine dyes, polymethine dyes, azomethine dyes, squarylium dyes, pyrylium and thiopyrylium salt dyes, dithiol metal complexes, and phthalocyanine dyes described in No. 347765. Particularly preferred are cyanine dyes, squarylium dyes, pyrylium salts, and phthalocyanine dyes.
[0070]
Examples of the pigment include 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, Kinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black, and the like can be used. Of these, carbon black is preferred.
As the metal fine particles, fine particles of Ag, Au, Cu, Sb, Ge and Pb are preferable, and fine particles of Ag, Au and Cu are more preferable.
[0071]
Specific examples of particularly suitable photothermal conversion agents are shown below, but the present invention is not limited thereto. Note that (IR-1) to (IR-11) are hydrophilic photothermal conversion agents suitable for addition to the image recording layer matrix, and (IR-21) to (IR-29) are A lipophilic photothermal conversion agent suitable for inclusion in capsules.
[0072]
[Chemical 1]

[0073]
[Chemical 2]

[0074]
[Chemical 3]

[0075]
[Formula 4]

[0076]
When added to the microcapsule, the addition amount of the photothermal conversion agent is preferably 1 to 50% by mass, more preferably 3 to 25% by mass based on the total content of the microcapsules. On the other hand, when the photothermal conversion agent is added to the image recording layer matrix, 1 to 50% by mass of the solid content of the recording layer is preferable, and 3 to 25% by mass is more preferable. In this range, good sensitivity can be obtained without impairing the film strength of the recording layer.
[0077]
(Acid generator)
In the recording layer according to the present invention, it is necessary to add an acid generator that generates an acid by heat and initiates and accelerates the reaction of the cationic polymerizable group in the image recording layer matrix. In this case, an acid generator may be added to at least one of the inside of the microcapsule and the image recording layer matrix, but from the viewpoint of stability, the recording layer should be separated from the cationically polymerizable compound and the microcapsule wall. It is preferable to add it to the matrix.
The acid generator can also form a print-out system in combination with a dye that changes color due to the generated acid.
As such an acid generator, a known acid precursor or a compound called an acid generator is preferably used. For example, an acid generator used for an acid generator for print-out image formation, a microresist or the like. Etc.
[0078]
More specifically, organic halogen compounds typified by trihalomethyl-substituted heterocyclic compounds described in JP-A-2002-29162, JP-A-2002-46361, JP-A-2002-137562, etc., iminosulfonates, etc. And compounds capable of generating a sulfonic acid by photolysis represented by (2), disulfone compounds, onium salts (for example, iodonium salts, diazonium salts, sulfonium salts, etc.). Moreover, the compound which introduce | transduced the group or compound which generate | occur | produces these acids into the polymer principal chain or side chain can also be used.
Hereinafter, although a specific example is given, this invention is not limited to these.
[0079]
[Chemical formula 5]

[0080]
[Chemical 6]

[0081]
[Chemical 7]

[0082]
[Chemical 8]

[0083]
[Chemical 9]

[0084]
Two or more of the above acid generators can be used in combination.
When added to the image recording layer matrix, the acid generator is preferably added in an amount of 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, based on the total solids of the recording layer. Within this range, good reaction initiation or acceleration effect can be obtained without impairing on-press developability.
[0085]
In the method of the present invention, the preliminary heating in the preliminary heating step not only suppresses the diffusion of the energy of the infrared beam used for image exposure to the support, but also initiates and accelerates the decomposition of the acid generator. By doing so, the capsule wall material becomes permeable, and the effect of improving the efficiency of the curing reaction between the cationically polymerizable compound released into the system and the acid is also obtained. For this reason, the preheating temperature is preferably equal to or higher than the temperature at which the decomposition of the acid generator starts and accelerates, and more preferably at least 10 ° C. above the decomposition temperature. Although the decomposition temperature of an acid generator changes with kinds of compound, in the case of diphenyl iodonium trifluoromethanesulfonic acid (AI-7 illustrated in this specification), it is about 160 degreeC, for example.
[0086]
Further, the recording layer according to the present invention can be added with a compound that is discolored by an acid in order to generate a printout image. As such a compound, for example, various dyes such as diphenylmethane, triphenylmethane, thiazine, oxazine, xanthene, anthraquinone, iminoquinone, azo, and azomethine are effectively used.
[0087]
Specific examples include brilliant green, ethyl violet, methyl green, crystal violet, basic fuchsin, methyl violet 2B, quinaldine red, rose bengal, methanyl yellow, thymol sulfophthalein, xylenol blue, methyl orange, paramethyl red, Congo Fred, Benzopurpurin 4B, α-Naphthyl Red, Nile Blue 2B, Nile Blue A, Methyl Violet, Malachide Green, Parafuchsin, Victoria Pure Blue BOH [manufactured by Hodogaya Chemical Co., Ltd.], Oil Blue # 603 [Orient Chemical Kogyo Co., Ltd.], Oil Pink # 312 [Orient Chemical Co., Ltd.], Oil Red 5B [Orient Chemical Co., Ltd.], Oil Scarlet # 308 [Orient Gaku Kogyo Co., Ltd.], Oil Red OG [Orient Chemical Co., Ltd.], Oil Red RR [Orient Chemical Co., Ltd.], Oil Green # 502 [Orient Chemical Co., Ltd.], Spiron Red BEH Special [made by Hodogaya Chemical Co., Ltd.], m-cresol purple, cresol red, rhodamine B, rhodamine 6G, sulforhodamine B, auramine, 4-p-diethylaminophenyliminonaphthoquinone, 2-carboxyanilino-4-p- Diethylaminophenyliminonaphthoquinone, 2-carboxystearylamino-4-pN, N-bis (hydroxyethyl) amino-phenyliminonaphthoquinone, 1-phenyl-3-methyl-4-p-diethylaminophenylimino-5-pyrazolone, 1-β-naphthyl-4- - dyes and p of diethylamino phenyl imino-5-pyrazolone, p ', p "- hexamethyl triamnotriphenylmethane (leuco crystal violet), and a leuco dye such as Pergascript Blue SRB (manufactured by Ciba-Geigy).
[0088]
In addition to the above, a leuco dye known as a material for thermal paper or pressure-sensitive paper is also suitable. Specific examples include crystal violet lactone, malachite green lactone, benzoylleucomethylene blue, 2- (N-phenyl-N-methylamino) -6- (Np-tolyl-N-ethyl) amino-fluorane, 2-anilino. -3-methyl-6- (N-ethyl-p-toluidino) fluorane, 3,6-dimethoxyfluorane, 3- (N, N-diethylamino) -5-methyl-7- (N, N-dibenzylamino) ) -Fluorane, 3- (N-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane, 3- (N, N-diethylamino) -6-methyl-7-anilinofluorane, 3 -(N, N-diethylamino) -6-methyl-7-xylidinofluorane, 3- (N, N-diethylamino) -6-methyl-7-chloro Fluorane, 3- (N, N-diethylamino) -6-methoxy-7-aminofluorane, 3- (N, N-diethylamino) -7- (4-chloroanilino) fluorane, 3- (N, N-diethylamino) -7-chlorofluorane, 3- (N, N-diethylamino) -7-benzylaminofluorane, 3- (N, N-diethylamino) -7,8-benzofluorane, 3- (N, N-dibutyl) Amino) -6-methyl-7-anilinofluorane, 3- (N, N-dibutylamino) -6-methyl-7-xylidinofluorane, 3-piperidino-6-methyl-7-anilinofluorane 3-pyrrolidino-6-methyl-7-anilinofluorane, 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide, 3,3-bis (1-n-butyl- -Methylindol-3-yl) phthalide, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl- 2-methylindol-3-yl) -4-zaphthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2-methylindol-3-yl) phthalide, and the like.
A suitable addition amount of the dye that changes color by the acid is 0.01 to 10% by mass with respect to the solid content of the recording layer.
[0089]
(Hydrophilic resin)
The recording layer matrix according to the present invention may contain a hydrophilic resin in order to improve the on-press developability, the film strength of the recording layer itself, and the heating efficiency when performing electromagnetic wave heating.
As hydrophilic resin, what has hydrophilic groups, such as a hydroxyl group, an amino group, a carboxy group, a phosphoric acid group, a sulfonic acid group, an amide group, is preferable, for example. In addition, the hydrophilic resin increases the image strength by reacting with the cationic polymerizable group possessed by the cationic polymerizable compound encapsulated in the microcapsule or the thermally reactive group possessed by the thermally polymerizable compound, thereby increasing the image resistance. Since it is printed, it preferably has a group that reacts with these functional groups. For example, when the cationically polymerizable compound has a vinyloxy group or an epoxy group, the hydrophilic resin preferably has a hydroxy group, a carboxy group, a phosphoric acid group, a sulfonic acid group, or the like. Among these, a hydrophilic resin having a hydroxy group or a carboxy group is preferable.
[0090]
Specific examples of hydrophilic resins include gum arabic, casein, gelatin, starch derivatives, soya gum, hydroxypropylcellulose, methylcellulose, carboxymethylcellulose and its sodium salt, cellulose acetate, sodium alginate, vinyl acetate-maleic acid copolymers, styrene-malein Acid copolymers, polyacrylic acids and their salts, polymethacrylic acids and their salts, homopolymers and copolymers of hydroxyethyl methacrylate, homopolymers and copolymers of hydroxyethyl acrylate, homopolymers and copolymers of hydroxypropyl methacrylate, hydroxypropyl acrylate Homopolymers and copolymers, hydroxybutyl methacrylate homopolymers and copolymers, Homopolymers and copolymers of butyl acrylate, polyethylene glycols, hydroxypropylene polymers, polyvinyl alcohols, hydrolyzed polyvinyl acetate having a degree of hydrolysis of at least 60% by weight, preferably at least 80% by weight, polyvinyl formal, polyvinyl pyrrolidone, acrylamide Homopolymers and copolymers, methacrylamide homopolymers and copolymers, N-methylolacrylamide homopolymers and copolymers, 2-acrylamido-2-methyl-1-propanesulfonic acid homopolymers and copolymers, 2-methacryloyloxyethylphosphonic acid And homopolymers and copolymers thereof.
The amount of the hydrophilic resin added is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total solid content of the recording layer.
[0091]
Further, the hydrophilic resin may be used after being cross-linked to such an extent that an unexposed portion can be developed on-press on a printing press. Examples of crosslinking agents used to crosslink hydrophilic resins include glyoxal, melamine formaldehyde resins, aldehydes such as urea formaldehyde resins, N-methylol urea, N-methylol melamine, methylol compounds such as methylolated polyamide resins, and divinyl. Active vinyl compounds such as sulfone and bis (β-hydroxyethylsulfonic acid), epoxy compounds such as epichlorohydrin, polyethylene glycol diglycidyl ether, polyamide, polyamine, epichlorohydrin adduct, polyamide epichlorohydrin resin, monochloroacetic acid Ester compounds such as esters and thioglycolic acid esters, polycarboxylic acids such as polyacrylic acid and methyl vinyl ether / maleic acid copolymer, boric acid, titanyl sulfate, C , Al, Sn, V, inorganic crosslinking agents such as Cr salts, and modified polyamide polyimide resin. In addition, a crosslinking catalyst such as ammonium chloride, a silane coupling agent, a titanate coupling agent can be used in combination.
[0092]
(Other additives)
In addition to the above, various compounds may be added to the recording layer matrix according to the present invention as necessary.
<Multifunctional monomer>
In order to further improve the printing durability, a polyfunctional monomer can be added. As this polyfunctional monomer, those exemplified as the monomer put in the microcapsule can be used. Among them, preferable monomers include trimethylolpropane triacrylate, pentaerythritol triacrylate, and the like. The addition amount of the polyfunctional monomer is preferably 0.1 to 10% by mass, and more preferably 0.5 to 5.0% by mass in the total solid content of the recording layer.
[0093]
<Thermal polymerization inhibitor>
In the present invention, it is desirable to add a small amount of a thermal polymerization inhibitor in order to prevent unnecessary thermal polymerization of the ethylenically unsaturated compound during preparation or storage of the recording layer coating solution. Suitable thermal polymerization inhibitors include hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, t-butylcatechol, benzoquinone, 4,4'-thiobis (3-methyl-6-t-butylphenol ), 2,2'-methylenebis (4-methyl-6-t-butylphenol), N-nitroso-N-phenylhydroxylamine aluminum salt and the like. The addition amount of the thermal polymerization inhibitor is preferably 0.01 to 5% by mass in the total solid content of the recording layer.
[0094]
<Inorganic fine particles>
Inorganic fine particles may be added to the recording layer matrix according to the present invention, and suitable examples of inorganic fine particles include silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate, or a mixture thereof. Even if they are not photothermally convertible, they can be used for strengthening the film and enhancing interfacial adhesion by surface roughening.
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, the microcapsules and the metal fine particles of the photothermal conversion agent are both stably dispersed in the hydrophilic resin, the film strength of the recording layer is sufficiently maintained, and the non-hydrophilic material having excellent hydrophilicity that hardly causes printing stains. An image portion can be formed.
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 recording layer is preferably 20% by mass or less, more preferably 10% by mass or less, based on the total solid content of the recording layer.
[0095]
<Surfactant>
In the recording layer matrix according to the present invention, JP-A-2-195356, JP-A-59-121044, JP-A-4-12044 are used for improving the dispersion stability of the recording layer, plate making and printing performance, and coating properties. Nonionic, anionic, cationic, amphoteric or fluorine-based surfactants described in No. 13149 and Japanese Patent Application No. 2001-169731 can be added. A suitable addition amount of these surfactants is 0.005 to 1% by mass of the total solid content of the recording layer.
[0096]
<Plasticizer>
In the recording layer matrix according to the present invention, a plasticizer can be added as needed to impart flexibility of the coating film. For example, polyethylene glycol, tributyl citrate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dioctyl phthalate, tricresyl phosphate, tributyl phosphate, trioctyl phosphate, tetrahydrofurfuryl oleate and the like are used.
[0097]
(Formation of image recording layer)
The recording layer according to the present invention is applied by preparing a coating solution by dissolving the necessary components described above in a solvent. Solvents used here include ethylene dichloride, cyclohexanone, methyl ethyl ketone, methanol, ethanol, propanol, ethylene glycol monomethyl ether, 1-methoxy-2-propanol, 2-methoxyethyl acetate, 1-methoxy-2-propyl acetate, dimethoxy Examples include ethane, methyl lactate, ethyl lactate, N, N-dimethylacetamide, N, N-dimethylformamide, tetramethylurea, N-methylpyrrolidone, dimethyl sulfoxide, sulfolane, γ-butyrolactone, toluene, water and the like. However, the present invention is not limited to this. These solvents are used alone or in combination. The solid content concentration of the coating solution is preferably 1 to 50% by mass.
[0098]
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.
[0099]
The recording layer coating amount (solid content) on the support obtained after coating and drying varies depending on the application, but is generally 0.5 to 5.0 g / m. ² Is preferred. As the coating amount decreases, the apparent sensitivity increases, but the film properties of the recording layer that performs the image recording function tend to decrease.
[0100]
[Overcoat layer]
The lithographic printing plate precursor according to the present invention is provided on the recording layer in order to protect the hydrophilic recording layer surface from contamination with lipophilic substances during storage and fingerprint trace contamination due to finger contact during handling. An overcoat layer containing a water-soluble resin described in JP-A-162961 and JP-A-2002-19318 can be provided.
[0101]
Specific examples of water-soluble resins used in the overcoat layer include natural gums such as gum arabic, water-soluble soybean polysaccharide, fiber derivatives (eg, carboxymethyl cellulose, carboxyethyl cellulose, methyl cellulose, etc.), modified products thereof, For synthetic polymers such as white dextrin, pullulan, and enzymatically degraded etherified dextrin, polyvinyl alcohol (polyvinyl acetate having a hydrolysis rate of 65% or more), polyacrylic acid, its alkali metal salt or amine salt, and polyacrylic acid Polymer, 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, polyhydroxy Ethyl acrylate, Polyvinyl Lupyrrolidone, its copolymer, polyvinyl methyl ether, vinyl methyl ether / maleic anhydride copolymer, poly-2-acrylamido-2-methyl-1-propanesulfonic acid, its alkali metal salt or amine salt, poly-2 -Acrylamido-2-methyl-1-propanesulfonic acid copolymer, its alkali metal salt or amine salt. 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.
[0102]
The overcoat layer may contain a photothermal conversion agent in order to improve sensitivity. A preferable photothermal conversion agent includes a water-soluble infrared absorbing dye. For example, (IR-1) to (IR-11) shown in the description of the recording layer are preferably used.
[0103]
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 overcoat layer in the total solid is preferably 0.05 to 5 mass%, more preferably 1 to 3 mass%.
[0104]
Furthermore, the overcoat layer can contain a compound having any one of fluorine atoms and silicon atoms described in JP-A No. 2001-341448 in order to prevent sticking between plates during stacking and storage.
The thickness of the overcoat layer according to the present invention is preferably 0.1 to 4.0 μm, and more preferably 0.1 to 1.0 μm. Within this range, it is possible to prevent the recording layer from being contaminated by an oleophilic substance without impairing the removability of the overcoat layer on the printing press.
[0105]
[Support]
The support that can be used for the lithographic printing plate precursor according to the present invention is a dimensionally stable plate-like material, for example, paper, paper laminated with plastic (for example, polyethylene, polypropylene, polystyrene, etc.), Metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate , Polyvinyl acetal, etc.), paper or plastic film on which the above metal is laminated or vapor-deposited. A preferable support is an aluminum plate.
[0106]
The aluminum plate is a pure aluminum plate and an alloy plate containing aluminum as a main component and containing a trace amount of different 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% by mass. 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.
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.
[0107]
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 recording layer.
The surface of the aluminum plate is roughened 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. In addition, 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. 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.
[0108]
The roughened aluminum plate is subjected to alkali etching treatment using an aqueous solution of potassium hydroxide or sodium hydroxide as necessary, and further neutralized, and then anodized to increase wear resistance as desired. Processing is performed.
As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid, or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte. The treatment conditions for anodization vary depending on the electrolyte used, and thus cannot be specified in general. However, in general, the electrolyte concentration is 1 to 80% by mass solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / day. dm ² A 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 / m ² It is preferable that
[0109]
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 for further improvement in adhesion to the upper layer, hydrophilicity, resistance to contamination, heat insulation and the like. If necessary, an aqueous solution containing an anodized film micropore enlargement treatment, micropore sealing treatment, and a hydrophilic compound described in JP-A Nos. 2001-253181 and 2001-322365 The surface hydrophilization treatment to be immersed can be appropriately selected and performed.
Suitable hydrophilic compounds for the hydrophilization treatment include polyvinylphosphonic acid, compounds having sulfonic acid groups, saccharide compounds, citric acid, alkali metal silicates, potassium potassium fluoride, phosphate / inorganic fluorine compounds, and the like. Can be mentioned.
[0110]
When using a support having insufficient surface hydrophilicity, such as a polyester film, as the support used in the present invention, it is desirable to apply a hydrophilic layer to make the surface hydrophilic. The hydrophilic layer includes at least one element selected from beryllium, magnesium, aluminum, silicon, titanium, boron, germanium, tin, zirconium, iron, vanadium, antimony, and a transition metal described in JP-A No. 2001-199175. 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.
[0111]
In the present invention, before applying the recording layer, an inorganic subbing layer such as a water-soluble metal salt such as zinc borate described in JP-A-2001-322365, or An organic subbing layer containing carboxymethyl cellulose, dextrin, polyacrylic acid or the like can be provided. The undercoat layer can contain the photothermal conversion agent.
[0112]
By applying the lithographic printing plate precursor having such a configuration to the image forming method of the present invention, an image portion having sufficient strength is formed by image exposure using infrared rays, so that the lithographic plate that can be developed on-machine The printing durability of the printing plate precursor has been improved, and it has become possible to obtain a large number of high-quality printed materials.
[0113]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these.
[Production of support]
Cleaning treatment was applied to molten metal of JIS A1050 alloy containing 99.5 mass% or more of aluminum and Fe 0.30 mass%, Si 0.10 mass%, Ti 0.02 mass%, and Cu 0.013 mass%. And cast. In the cleaning process, a degassing process was performed to remove unnecessary gases such as hydrogen in the molten metal, and a ceramic tube filter process was performed. The casting method was a DC casting method. The solidified 500 mm thick ingot was chamfered 10 mm from the surface and homogenized at 550 ° C. for 10 hours so as not to coarsen the intermetallic compound.
[0114]
Next, after hot rolling at 400 ° C. and intermediate annealing at 500 ° C. for 60 seconds in a continuous annealing furnace, cold rolling was performed to obtain an aluminum rolled plate having a plate pressure of 0.30 mm. By controlling the surface roughness of the rolling roll, the centerline average surface roughness Ra after cold rolling was controlled to 0.2 μm. Then, it applied to the tension leveler in order to improve planarity.
[0115]
Next, a surface treatment for making a lithographic printing plate support was performed. First, in order to remove the rolling oil on the surface of the aluminum plate, degreasing treatment was carried out with a 10% by mass sodium aluminate aqueous solution at 50 ° C. for 30 seconds, and neutralization and smut removal treatment were carried out with a 30% by mass sulfuric acid aqueous solution at 50 ° C. for 30 seconds. Next, in order to improve the adhesion between the support and the recording layer and to provide water retention to the non-image area, a so-called graining treatment was performed to roughen the surface of the support. An aqueous solution containing 1% by mass of nitric acid and 0.5% by mass of aluminum nitrate is maintained at 45 ° C., and the current density is 20 A / dm by an indirect power feeding cell while flowing the aluminum web into the aqueous solution. ² , Anode side electricity quantity 240C / dm with alternating waveform with duty ratio 1: 1 ² Electrolytic graining was performed by giving Thereafter, an etching treatment was performed with a 10% by mass aqueous sodium aluminate solution at 50 ° C. for 30 seconds, and a 30% by mass sulfuric acid aqueous solution was subjected to neutralization and smut removal treatment at 50 ° C. for 30 seconds. Furthermore, in order to improve wear resistance, chemical resistance and water retention, an oxide film was formed on the support by anodic oxidation. A 20% by weight aqueous solution of sulfuric acid was used as the electrolyte at 35 ° C., and the aluminum web was carried into the electrolyte while the indirect power supply cell was used to provide 14 A / dm. ² 2.5 g / m by electrolytic treatment with direct current ² An anodic oxide film was prepared.
[0116]
Thereafter, a silicate treatment was performed to ensure hydrophilicity as a non-image portion of the printing plate. The treatment was carried in such a way that a No. 3 sodium silicate 1.5 mass% aqueous solution was kept at 70 ° C. so that the contact time of the aluminum web was 15 seconds and further washed with water. The amount of Si deposited is 10 mg / m ² Met. The center line surface roughness Ra of the support produced as described above was 0.25 μm.
[0117]
[Synthesis of microcapsules encapsulating a cationically polymerizable compound]
As an oil phase component, 4.5 g of bis (vinyloxyethyl) ether of bisphenol A, an adduct of trimethylolpropane and xylylene diisocyanate (Takenate D-110N, manufactured by Mitsui Takeda Chemical Co., Ltd., microcapsule wall material) 5 g Millionate MR-200 (Nippon Polyurethane Co., Ltd. aromatic isocyanate oligomer, microcapsule wall material) 3.75 g, Infrared absorbing dye (IR-27 described herein) 1.5 g, Pionine A41C (Takemoto Yushi Co., Ltd.) ) Surfactant) 0.1 g was dissolved in 18.4 g of ethyl acetate. As an aqueous phase component, 37.5 g of a 4 mass% aqueous solution of PVA205 (Kuraray polyvinyl alcohol) was prepared. The oil phase component and the aqueous phase component were emulsified at 12000 rpm for 10 minutes using a homogenizer. Thereafter, a solution obtained by dissolving 0.38 g of tetraethylenepentamine (pentafunctional amine, microcapsule wall cross-linking agent) in 26 g of water was added, followed by stirring at 65 ° C. for 3 minutes while cooling with water. The microcapsule solution thus obtained had a solid content concentration of 24% by mass and an average particle size of 0.3 μm.
[0118]
[Example 1]
(Preparation of lithographic printing plate precursor)
The following recording layer coating solution containing the microcapsules of the synthesis example was bar-coated on the aluminum substrate obtained in the above production example, and then dried in an oven at 100 ° C. for 60 seconds. 0g / m ² A lithographic printing plate precursor was prepared.
<Recording layer coating solution>
・ 35.4g of water
・ 9.0 g of microcapsule liquid in the above synthesis example
Acid generator (AI-7 as described herein) 0.24 g
[0119]
(Exposure / printing and evaluation)
The lithographic printing plate precursor obtained as described above is the image exposure apparatus 10 according to the first embodiment described with reference to FIGS. 1 to 5 or the image according to the second embodiment described with reference to FIG. The lithographic printing plate precursor is preheated to 160 ° C. to 180 ° C. using the exposure apparatus 100, and after 30 to 100 seconds, the output is 17 W and the external drum rotation speed is 100 rpm on a Trend setter 3244VX manufactured by Creo equipped with a water-cooled 40 W infrared semiconductor laser. Then, image exposure was performed under the condition of a resolution of 2400 dpi. During this exposure, the contact surface of the lithographic printing plate precursor support (aluminum plate) with the recording layer and the surface temperature of the image recording layer were kept at 70 ° C. or higher. Thereby, in the planographic printing plate, thermal diffusion from the exposed portion of the recording layer to the support is effectively suppressed during exposure with the IR laser L. As a result, even near the interface between the recording layer and the support, the collapse of the microcapsule wall or the improvement of permeability is effectively promoted, the decomposition reaction of the acid generator is promoted, and the mobility of the cationic polymerizable compound is increased. And the polymerization and curing reaction proceeded efficiently, so that a strong and excellent printing durability image could be formed.
[0120]
After completion of image exposure, the lithographic printing plate precursor was attached to a cylinder of a printing machine SOR-M manufactured by Heidelberg without developing. 4% by volume IF102 (Fuji Photo Film Co., Ltd.) A dampening solution made of an aqueous solution and Barius Ink Ink (Dainippon Ink Chemical Co., Ltd.) are used to supply the dampening water, and then the ink is supplied. Further, paper was supplied for printing.
[0121]
At this time, the recording layer in the non-image area was removed at the initial stage of the printing process, and a high-quality printed matter without the stain on the non-image area was obtained. After that, printing was continued, and the number of sheets was visually measured to determine whether the non-image area was free of stains and the image area could be printed with a sufficient ink density, and used as an index of printing durability. The larger the number, the better the printing durability.
As a result, 35,000 high-quality printed materials were obtained, and it was confirmed that the lithographic printing plate on which an image was formed by the method of the present invention had excellent printing durability that could withstand practicality. .
[0122]
【The invention's effect】
According to the present invention, after image exposure using infrared rays, an image can be formed without passing through a special liquid development processing step, and an image forming method capable of obtaining a lithographic printing plate excellent in printing durability. And this image forming method can be obtained.
[Brief description of the drawings]
FIG. 1 is a side view showing a configuration of an image exposure apparatus according to a first embodiment of the present invention.
2 is a perspective view showing a configuration of an exposure head and its feed mechanism in the image exposure apparatus shown in FIG. 1. FIG.
3 is a perspective view showing a configuration of a preheating device in the image exposure apparatus shown in FIG. 1. FIG.
4 is a side view of the preheating device shown in FIG. 3. FIG.
5 is a perspective view showing a configuration of a coil unit in the preheating device shown in FIG. 3. FIG.
FIG. 6 is a side view showing a configuration of an image exposure apparatus according to a second embodiment of the present invention.
[Explanation of symbols]
10, 100 Image exposure apparatus
12 Planographic printing plate precursor
14 Casing
16 Plate stand
18 Discharge tray
20 Outer drum
22 Chuck mechanism
26 Exposure head
28 Exposure head feed mechanism
32 LD light source device
38 Preheating device
46 Heating member
102 autoloader

Claims (3)

An image forming method for forming an image on a lithographic printing plate precursor comprising an image recording layer comprising a microcapsule encapsulating a cationically polymerizable compound, an acid generator, and a photothermal conversion agent on a support. There,
A preheating step of heating the lithographic printing plate precursor to a predetermined preheating temperature;
An image exposure step of exposing the lithographic printing plate precursor heated to the preheating temperature with infrared rays to form an image on the image recording layer of the lithographic printing plate precursor;
An image forming method comprising: The image forming method according to claim 1, wherein the preheating temperature is set to a temperature selected from a range of 50 ° C. to 230 ° C. An image exposure apparatus used in the image forming method according to claim 1 or 2,
A holding member for holding the lithographic printing plate precursor, the lithographic printing plate precursor being mountable;
Preheating means for heating the lithographic printing plate precursor to be mounted on the holding member to the preheating temperature by heat energy or electromagnetic energy supplied from a heat supply section that is linearly or planarly spread;
Exposure means for exposing the lithographic printing plate precursor held by the holding member with infrared rays to form an image on the image recording layer of the lithographic printing plate precursor;
An image exposure apparatus comprising:

Images