JP4075283B2 - Printing plate material and manufacturing method thereof - Google Patents

Description

【００７３】
（式中、２つのＲ¹は各々独立して、水素原子、メチル基、フェニル基又はビニル基を示し、ｙは１以上の整数を示す。）上記一般式（１）で表される化合物のうちＲ¹がメチル基であるものが好ましい。該オルガノポリシロキサンの重量平均分子量（以下、Ｍｗと略す）は５，０００〜１，０００，０００であり、好ましくは１０，０００〜１，０００，０００である。Ｍｗが著しく低いとシリコーンゴム層の膜強度が低下し、耐印刷性が低くなり、またＭｗが著しく高いとアブレーションによるシリコーンゴム層の除去効果が低下し、感度低下、画像再現性の低下を起こしやすい。
【００７４】
また、本発明に用いられる反応性シラン化合物は、前記両末端に水酸基を有する線状オルガノポリシロキサンの水酸基と反応し、脱酢酸型、脱オキシム型、脱アルコール型、脱アミノ型あるいは脱水型等の縮合を起こし架橋することができる官能基を、少なくとも２つ以上有する分子量２，０００以下の反応性シラン化合物である。該官能基としては、具体的には例えば、下記各式で表される官能基が挙げられる。
【００７５】
【化２】

【００７６】
（式中、Ｒ²は炭素数１〜５のアルキル基を示すが同一原子団に２個のＲ²がある場合、それぞれは同一でも異なっていても良い。）これらのうち、官能基がアシルオキシ基（−ＯＣＯＲ²）で官能基数が３以上のもの、あるいは官能基がアルコキシ基（−ＯＲ²）で官能基数が３以上のものは、塗布後の乾燥処理後において短時間にシリコーンゴム層を形成するため好ましい。更に好ましくは、官能基がアセトキシ基で官能基数が３以上のもの、あるいは官能基がアルコキシ基で官能基数が６以上のものである。
【００７７】
該反応性シラン化合物としては例えば下記一般式（２）〜（５）で表される化合物を挙げることができる。式中Ｑは前記した両末端に水酸基を有する線状オルガノポリシロキサンの水酸基と反応する官能基から選ばれたものを表し、Ｑは１分子中に少なくとも２個有するものとする。
【００７８】
【化３】

【００７９】
（式中、Ｘは炭素数１〜５のアルキル基、フェニル基、ビニル基、Ｈ₂Ｎ−（ＣＨ₂）_h−、ＣＨ₂＝Ｃ（ＣＨ₃）ＣＯ−、ＣＨ₂＝ＣＨＣＯ−、
【００８０】
【化４】

【００８１】
を示し、Ｗは酸素原子、硫黄原子、−ＳＳＳＳ−、炭素数１〜１０のアルキレン基、または−Ｎ（Ｒ⁴）−（ＣＨ₂）_q−Ｎ（Ｒ⁴）−を示し、Ｒ²は前記と同様に炭素数１〜５のアルキル基を示し、Ｒ³はアリル基又は−（ＣＨ₂）_q−ＳｉＲ² _3-pＱ_pを示し、Ｒ⁴は水素原子、炭素数１〜５のアルキル基、又はフェニル基を示すが、Ｒ²、Ｒ³、Ｒ⁴のそれぞれが同一分子内に複数存在する場合、その複数個のそれぞれは同一でも異なっていても良く、ｈ、ｊ及びｑは各々１〜５の整数を示し、ｐ及びｒは各々１〜３の整数を示し、ｓは２〜４の整数を示し、ｔ及びｕは各々０〜５の整数を示す。）本発明に用いられる反応性シラン化合物について下記にさらに具体的な例を挙げるが、これら例示されるものに限定されるものではない。
【００８２】
【化５】

【００８３】
【化６】

【００８４】
【化７】

【００８５】
本発明に使用される縮合架橋タイプのシリコーンゴム層は、上記の両末端に水酸基を有するオルガノポリシロキサンと反応性シラン化合物の縮合架橋反応の反応効率を高めるため、有機カルボン酸、チタン酸エステル、錫酸エステル、アルミ有機エーテル、白金系触媒等の縮合触媒を適宜混合させ縮合反応を行い硬化させる。
【００８６】
本発明において用いられる両末端に水酸基を有するオルガノポリシロキサン、反応性シラン化合物及び縮合触媒のシリコーンゴム層中での配合率は、全シリコーンゴム層の固形分に対し、両末端水酸基を有するオルガノポリシロキサンが８０〜９８質量％、好ましくは８５〜９８質量％、反応性シラン化合物が、通常２〜２０質量％、好ましくは２〜１５質量％、さらに好ましくは２〜７質量％、縮合触媒が０．０５〜５質量％、好ましくは０．１〜３質量％、さらに好ましくは０．１〜１質量％である。
【００８７】
反応性シラン化合物、或いは、縮合触媒の割合が著しく高いとインク反撥性が低下し、また、アブレーション時のシリコーンゴム層の除去が困難になり、感度及び画像再現性が低下する。また、反対に著しく低いとシリコーンゴム層の膜強度が低下し、印刷耐久性が低下する。
【００８８】
本発明に使用される縮合架橋タイプのシリコーンゴム層には、シリコーンゴム層のインク反撥性を高めるために、上記の両端に水酸基を有するポリオルガノシロキサン以外のポリシロキサンをシリコーンゴム層全固形分に対し、２〜１５質量％、好ましくは３〜１２質量％含有させることが出来る。該ポリシロキサンとしては例えば、両末端がトリメチルシリル化されたＭｗ１０，０００〜１，０００，０００のポリジメチルシロキサン等が挙げられる。
【００８９】
次に、本発明に用いられる付加架橋タイプのシリコーンゴム層は、１分子中に脂肪族不飽和基を少なくとも２個有するオルガノポリシロキサンと、該オルガノポリシロキサンと架橋しシリコーンゴム層を形成させる、１分子中にＳｉ−Ｈ結合を少なくとも２個有するオルガノポリシロキサンを必須成分として含むものである。
【００９０】
本発明に使用される１分子中に脂肪族不飽和基を少なくとも２個有するオルガノポリシロキサンは、その構造が、鎖状、環状、分岐状のいずれでもよいが、鎖状が好ましい。脂肪族不飽和基の例としては、ビニル基、アリル基、ブテニル基、ペンテニル基、ヘキセニル基等のアルケニル基；シクロペンテニル基、シクロヘキセニル基、シクロヘプテニル基、シクロオクテニル基等のシクロアルケニル基；エチニル基、プロピニル基、ブチニル基、ペンチニル基、ヘキシニル基等のアルキニル基等が挙げられる。これらのうち、反応性の点から末端に不飽和結合を有するアルケニル基が好ましく、ビニル基が特に好ましい。また、脂肪族不飽和基以外の残余の置換基は、良好な印刷インク反撥性を得るためにメチル基が好ましい。
【００９１】
１分子中に脂肪族不飽和基を少なくとも２個有するオルガノポリシロキサンのＭｗは通常５００〜５００，０００であり、好ましくは１，０００〜３００，０００である。Ｍｗが著しく低いと、シリコーンゴム層の強度が低下し、印刷時にシリコーンゴム層に傷がつきやすく、その部分の印刷インク反撥性が低下し、インクが付着しやすくなり、印刷汚れの原因となる。また、Ｍｗが著しく高いと、アブレーションによるシリコーンゴム層の除去が不良となり、感度の低下、画像再現性の低下を起こしやすい。
【００９２】
本発明に使用される１分子中にＳｉ−Ｈ結合を少なくとも２個有するオルガノポリシロキサンは、その構造が、鎖状、環状、分岐状のいずれでもよいが、鎖状が好ましい。Ｓｉ−Ｈ結合は、シロキサン骨格の末端あるいは中間のいずれにあっても良く、置換基の総数に対する水素原子の占める割合は通常１〜６０％であり、好ましくは２〜５０％である。また、水素原子以外の残余の置換基は良好な印刷インク反撥性を得るためにメチル基が好ましい。１分子中にＳｉ−Ｈ結合を少なくとも２個有するオルガノポリシロキサンのＭｗは通常３００〜３００，０００であり、好ましくは５００〜２００，０００である。Ｍｗが著しく高いと感度の低下、画像再現性の低下を起こしやすい。
【００９３】
上記の１分子中に脂肪族不飽和基を少なくとも２個有するオルガノポリシロキサンと１分子中にＳｉ−Ｈ結合を少なくとも２個有するオルガノポリシロキサンを付加反応させるために、通常、付加反応触媒を用いる。この付加反応触媒としては、公知のものの中から任意に選ぶことができるが、白金系触媒が好ましく、白金族金属及び白金族系化合物から選ばれる１種又は２種以上の混合物が使用される。白金族金属としては、白金の単体（例えば白金黒）、パラジウムの単体（例えばパラジウム黒）、ロジウムの単体等が例示される。また白金族系化合物としては、塩化白金酸、白金−オレフィン錯体、白金−アルコール錯体、白金−ケトン錯体、白金とビニルシロキサンの錯体、テトラキス（トリフェニルホスフィン）白金、テトラキス（トリフェニルホスフィン）パラジウム等が例示される。これらの内でも、塩化白金酸又は白金−オレフィン錯体をアルコール系溶剤、ケトン系溶剤、エーテル系溶剤、炭化水素系溶剤などに溶解したものが特に好ましい。
【００９４】
前記したシリコーンゴム層を形成する各組成物の配合率は、シリコーンゴム層の全固形分に対して、１分子中に脂肪族不飽和基を少なくとも２個有するオルガノポリシロキサンが、８０〜９８質量％、好ましくは８５〜９８質量％であり、１分子中にＳｉ−Ｈ結合を少なくとも２個有するオルガノポリシロキサンが、２〜２０質量％、好ましくは２〜１５質量％であり、付加反応触媒が、０．００００１〜１０質量％、好ましくは０．０００１〜５質量％である。
【００９５】
１分子中にＳｉ−Ｈ結合を少なくとも２個有するオルガノポリシロキサンの配合率が著しく低いとシリコーンゴム層の膜強度が低下し、印刷インク反撥性及び耐印刷性が低下し、配合率が著しく高いと感度及び画像再現性が低下する。また、本発明に用いられる付加架橋タイプのシリコーンゴム層には、上記の組成の他に、さらにシリコーンゴム層の膜強度を高める目的で、下記一般式（６）で表される加水分解性基を有するアミノ系有機ケイ素化合物を添加することができる。
【００９６】
【化８】

【００９７】
（式中、Ｚは加水分解性基を示し、Ｒ⁵は２価の炭化水素基を示し、Ｒ⁶は１価の置換されていてもよい炭化水素基を示し、２つのＲ⁷は各々独立して水素原子、１価の置換されていても良い炭化水素基あるいは−Ｒ⁵−ＳｉＲ⁶ _3-pＺ_pで表される基を示し、ｐは１〜３の整数を示す。）
Ｚで表される加水分解性基としては例えば、メトキシ基、エトキシ基、プロポキシ基等のアルコキシ基；２−プロペニルオキシ基等のアルケニルオキシ基；フェノキシ基等のアリールオキシ基；アセチルオキシ基等のアシルオキシ基等が挙げられる。これらのうち、安定性、硬化性などの点からメトキシ基、エトキシ基、アセチルオキシ基が好ましい。Ｒ⁵の二価の炭化水素基としては例えば、
【００９８】
【化９】

【００９９】
が好ましい。Ｒ⁶及びＲ⁷で表される置換基のうち一価の置換されていてもよい炭化水素基としては例えば、メチル基、エチル基、プロピル基、ブチル基等のアルキル基；シクロプロピル基、シクロブチル基、シクロペンチル基、シクロヘキシル基、シクロヘプチル基、シクロオクチル基等のシクロアルキル基；ビニル基、アリル基、ブテニル基、ペンテニル基、ヘキセニル基、等のアルケニル基；シクロペンテニル基、シクロヘキセニル基、シクロヘプテニル基、シクロオクテニル基等のシクロアルケニル基；グリシドキシプロピル基、アクリロキシプロピル基、メタクリロキシプロピル基、アミノエチル基等の置換アルキル基等が挙げられる。硬化性の点からＲ⁶及びＲ⁷はビニル基、アリル基、グリシジル基、メタクリル基、又はγ−グリシドキシプロピル基が好ましい。
【０１００】
該アミノ系ケイ素化合物の具体例としては例えば、３−〔Ｎ−アリル−Ｎ−（２−アミノエチル）〕アミノプロピルトリメトキシシラン、３−（Ｎ−アリル−Ｎ−グリシジル）アミノプロピルトリメトキシシラン、３−（Ｎ−アリル−Ｎ−メタクリル）アミノプロピルトリメトキシシラン、Ｎ−グリシジル−Ｎ，Ｎ−ビス〔３−（メチルジメトキシシリル）プロピル〕アミン、Ｎ−グリシジル−Ｎ，Ｎ−ビス〔３−（トリメトキシシリル）プロピル〕アミン、アミノプロピルトリメトキシシラン、アミノプロピルトリアセチルオキシシラン、３−〔Ｎ−アリル−Ｎ−（２−アミノエチル）〕アミノプロピルトリアセチルオキシシラン、３−（Ｎ−アリル−Ｎ−グリシジル）アミノプロピルトリアセチルオキシシラン、３−（Ｎ−アリル−Ｎ−メタクリル）アミノプロピルトリアセチルオキシシラン等が挙げられる。これらは２種類以上を混合して用いてもよい。
【０１０１】
該アミノ系の有機ケイ素化合物はシリコーンゴム層の全固形分に対して０〜１０質量％、好ましくは０〜５質量％である。また、本発明に用いられる付加架橋タイプのシリコーンゴム層には、シリコーンゴム層を塗設する際に、シリコーン層組成の急激な硬化を防ぐ目的で、硬化遅延剤を添加することができる。硬化遅延剤としては一般的に知られているアセチレン系アルコール、マレイン酸エステル、アセチレン系アルコールのシリル化物、マレイン酸のシリル化物、トリアリルイソシアヌレート、ビニルシロキサン等から、任意に選ぶことができる。
【０１０２】
該硬化遅延剤の添加量は所望の硬化速度によって異なるが、通常シリコーンゴム層の全固形分に対し、０．０００１〜１．０質量部である。上記した本発明に用いられる縮合架橋タイプ及び付加架橋タイプのシリコーンゴム層には、その強度を向上させる目的で、シリカ、酸化チタン、酸化アルミニウムなどの無機質充填剤を添加しても良く、特にシリカが好ましく用いられる。このような充填剤としては分散性あるいは分散安定性の点から平均粒子径５００μｍ以下のものが好ましい。
【０１０３】
これらのシリコーンゴム層は印刷インク反撥性、耐印刷性に優れ、さらにアブレーションにより容易に除去され、高感度で、高い画像再現性を与える機能を有する。該シリコーンゴム層の引掻傷強度は１０〜１００ｇであることが好ましい。ただし、引掻傷強度とは、先端の直径が０．２ｍｍのサファイア針を印刷版上に加重を加えながら１０ｃｍ／分のスピードで移動させた際、引掻傷が発生するために必要な加重（ｇ）を表す。引掻傷強度が上記範囲であれば、印刷インク反撥性、耐印刷性、感度、画像再現性等の印刷適性が良好となる。本発明において用いられるシリコーンゴム層の膜厚は０．１〜１０μｍ、好ましくは０．２〜５μｍ、さらに好ましくは０．３〜２μｍである。
【０１０４】
以上に記載した光熱変換層組成物、シリコーンゴム層組成物は、適当な溶剤に溶解して溶液となし、これを支持体にワイヤーバー、スピナー、ロールコーター等の各種の塗布装置により前記基板上に塗布した後、乾燥して、それぞれ光熱変換層、シリコーンゴム層を形成することができる。光熱変換層の塗布溶剤としては、例えばメチルエチルケトン、シクロヘキサノン等のケトン類、酢酸ブチル、酢酸アミル、プロピオン酸エチル等のエステル類、トルエン、キシレン、モノクロロベンゼン、四塩化炭素、トリクロロエチレン、トリクロロエタン等の炭化水素やハロゲン化炭化水素類、メチルセロソルブ、エチルセロソルブ、テトラヒドロフラン等のエーテル類、さらにはプロピレングリコールモノメチルエーテルアセテート、ベントキソン、ジメチルホルムアミドなど常用のものを用いることができ、シリコーンゴム層の塗布溶剤としては、ｎ−ヘキサン、シクロヘキサン、石油エーテル、脂肪族炭化水素系溶剤エクソン化学（株）製：アイソパーＥ、Ｈ、Ｇ及びこれらの溶剤と上記の光熱変換層塗布溶剤との混合溶媒等を用いることができる。
【０１０５】
また、本発明に用いられるシリコーンゴム層を塗設する際には、光熱変換層とシリコーンゴム層との接着性を高める目的で、光熱変換層とシリコーンゴム層との間に接着層を設けることができる。この接着層には、通常、前述の光熱変換層の説明中に記載した有機高分子物質及び、シリコーンゴム層の説明中に記載したシリコーンゴムの中から適宜選択して用いることができるが、好ましくはウレタン性の有機高分子物質或いは、多官能アルコキシシラン、多官能アセトキシシラン等の縮合型反応性シラン化合物と、両末端或いは主鎖中に水酸基等の反応性基を有するポリジメチルシロキサンとの組み合わせ組成が用いられる。更に具体的には、東洋紡績社製バイロン３００、バイロンＵＲ８２００、東レシリコーン社製プライマーＡ、プライマーＢ、プライマーＣ、プライマーＤ、プライマーＤ２、プライマーＥ、また、武田薬品社製タケネートＡ３６７ＨとタケネートＡ−７との組み合わせ、タケネートＡ−９６９０とタケネートＡ−５との組み合わせ、タケネートＡ−９６８とタケネートＡ−８との組み合わせ等を挙げることができる。これらの接着層は、通常、乾燥膜厚０．０５〜１０μｍ、好ましくは０．１〜２μｍとなるように塗布、乾燥して用いられる。
【０１０６】
また、必要に応じて、シリコーンゴム層を保護する目的で、ポリプロピレンシート、ポリエチレンシート、離型処理ポリエチレンテレフタレート等の各種離型性プラスチックシート、離型処理紙、アルミ、鉄、銅等の金属シート等をシリコーンゴム層上にラミネートし設けることができる。上記の光熱変換層及びシリコーンゴム層を基板上に設けた感光性印刷版は、通常６８０〜１２００ｎｍの近赤外光を発振する半導体レーザー光を５〜３０μｍ径に集光したビームスポットにより走査露光を行い、露光部分をアブレーションさせた後、後処理なしに印刷版として使用されるが、該露光済み印刷版上に付着したアブレーションで発生した光熱変換層或いはシリコーンゴム層の微粒子を除去する目的で、シリコーンゴム層表面を必要に応じて水溶液又は有機溶剤を供給しながらブラシ、パッド、超音波、スプレー等の物理刺激を与える後処理を行ってもよい。
【０１０７】
また、該アブレーションで発生した微粒子を除去する他の方法としては、該微粒子に対してシリコーンゴム層より接着性の高い表面を有するカバーシートを露光済の感光性印刷版のシリコーンゴム層上に、シリコーンゴム表面と接着性のカバーシート表面が合わさるようにラミネートした後、剥離する方法や、露光前に、該カバーシートであってレーザー光を透過させるカバーシートを上記と同様にラミネートし、露光後に剥離、シリコーンゴム層上の微粒子を除く方法等が挙げられる。該カバーシートとしては、ポリエチレンテレフタレート、ポリプロピレン、ポリカーボネート、紙等の基版上に、シリコーンゴム、アイオノマー、酢酸ビニル等の粘着層を必要に応じて設けたものが挙げられる。
【０１０８】
なお、シリコーンゴム層を設ける際の、光熱変換層は、インク反撥性層でないことが好ましい。
【０１０９】
本発明を湿し水使用の印刷版作製用の印刷版材料に適用するとき、本発明の光熱変換粒子を含有する層自体を親水性に、より好ましくは親水性で多孔質な塗膜とするか、もしくは光熱変換粒子を含有する層の上に親水性層を設ける。これらの親水性層表面が印刷版の非画像部となる。さらにその上に熱による画像形成機能を有する層を設置するか、もしくは親水性層自体に熱により親油性に変化する機能を付与することによって、ヒートモードレーザー露光での画像形成が可能となる。印刷版用材料についてさらに詳細に説明する。
【０１１０】
印刷版用材料は支持体（基材）と、１以上の構成層とを有する。好ましくは、構成層が多孔質であることが好ましく、より好ましくは、構成層が多孔質粒子を含有する。印刷版用材料は、平版印刷版用材料（ｐｌａｎｏｇｒａｐｈｉｃ ｐｒｉｎｔｉｎｇ ｐｌａｔｅ）であることが好ましい。また、各種印刷版はＣＴＰ用として使用可能なものであるが、それに限られるものではない。
【０１１１】
印刷版用材料としては、構成層として、光熱変換層が画像記録層を兼ねている印刷版用材料と、光熱変換層の他に画像記録層を有している印刷版用材料とが挙げられる。光熱変換層が画像記録層を兼ねている場合は、光熱変換層が親水性層であることが好ましく、その光熱変換層の露光部が、インク受容性に変化することが好ましい。また、光熱変換層と画像記録層とが異なる場合は、画像記録層全体がインキ受容性層であってもよく、もしくは、画像記録層は親水性層であって、その画像記録層の露光部がインキ受容性に変化するようにしてもよい。また、画像記録層の上にさらに親水性層を設けるようにしてもよい。この画像記録層は熱に溶融する素材を含有することが好ましい。
【０１１２】
上記親水性層に添加可能な素材としては下記ａ〜ｅ等が挙げられる。
ａ．多孔質シリカまたは多孔質アルミノシリケート粒子
多孔質シリカ粒子は一般に湿式法または乾式法により製造される。湿式法ではケイ酸塩水溶液を中和して得られるゲルを乾燥、粉砕するか、中和して析出した沈降物を粉砕することで得ることができる。乾式法では四塩化珪素を水素と酸素とともに燃焼し、シリカを析出することで得られる。これらの粒子は製造条件の調整により多孔性や粒径を制御することが可能である。多孔質シリカ粒子としては、湿式法のゲルから得られるものが特に好ましい。
【０１１３】
多孔質アルミノシリケート粒子は例えば特開平１０−７１７６４号に記載されている方法により製造される。すなわち、アルミニウムアルコキシドと珪素アルコキシドを主成分として加水分解法により合成された非晶質な複合体粒子である。粒子中のアルミナとシリカの比率は１：４〜４：１の範囲で合成することが可能である。また、製造時にその他の金属のアルコキシドを添加して３成分以上の複合体粒子として製造したものも本発明に使用できる。これらの複合体粒子も製造条件の調整により多孔性や粒径を制御することが可能である。
【０１１４】
粒子の多孔性としては、分散前の状態で、細孔容積で１．０ｍｌ／ｇ以上であることが好ましく、１．２ｍｌ／ｇ以上であることがより好ましく、１．８ｍｌ／ｇ以上２．５ｍｌ／ｇ以下であることがさらに好ましい。細孔容積は塗膜の保水性と密接に関連しており、細孔容積が大きいほど保水性が良好となって印刷時に汚れにくく、水量ラチチュードも広くなるが、２．５ｍｌ／ｇよりも大きくなると粒子自体が非常に脆くなるため塗膜の耐久性が低下する。細孔容積が１．０ｍｌ／ｇ未満の場合には、印刷時の汚れにくさ、水量ラチチュードの広さが不充分となる。
【０１１５】
粒径としては、親水性層に含有されている状態で（分散破砕工程を経た場合も含めて）、実質的に１μｍ以下であることが好ましく、０．５μｍ以下であることがさらに好ましい。粗大な粒子が存在すると親水性層表面に多孔質で急峻な突起が形成され、突起周囲にインクが残りやすくなって非画線部汚れが劣化する。
【０１１６】
ｂ．ゼオライト粒子
ゼオライトは結晶性のアルミノケイ酸塩であり、細孔径が０．３〜１ｎｍの規則正しい三次元網目構造の空隙を有する多孔質体である。天然および合成ゼオライトを合わせた一般式は、次のように表される。
【０１１７】
（ＭＩ，ＭII_1/2）_m（Ａｌ_mＳｉ_nＯ_2(m+n)）・ｘＨ₂Ｏ
ここで、ＭＩ、ＭIIは交換性のカチオンであって、ＭＩはＬｉ⁺、Ｎａ⁺、Ｋ⁺、Ｔｌ⁺、Ｍｅ₄Ｎ⁺（ＴＭＡ）、Ｅｔ₄Ｎ⁺（ＴＥＡ）、Ｐｒ₄Ｎ⁺（ＴＰＡ）、Ｃ₇Ｈ₁₅Ｎ₂ ⁺、Ｃ₈Ｈ₁₆Ｎ⁺等であり、ＭIIはＣａ²⁺、Ｍｇ²⁺、Ｂａ²⁺、Ｓｒ²⁺、Ｃ₈Ｈ₁₈Ｎ₂ ²⁺等である。また、ｎ≧ｍであり、ｍ／ｎの値つまりはＡｌ／Ｓｉ比率は１以下となる。Ａｌ／Ｓｉ比率が高いほど交換性カチオンの量が多く含まれるため極性が高く、したがって親水性も高い。好ましいＡｌ／Ｓｉ比率は０．４〜１．０であり、さらに好ましくは０．８〜１．０である。
【０１１８】
本発明で使用するゼオライト粒子としては、Ａｌ／Ｓｉ比率が安定しており、また粒径分布も比較的シャープである合成ゼオライトが好ましく、たとえば、ゼオライトＡ：Ｎａ₁₂（Ａｌ₁₂Ｓｉ₁₂Ｏ₄₈）・２７Ｈ₂Ｏ；Ａｌ／Ｓｉ比率１．０、ゼオライトＸ：Ｎａ₈₆（Ａｌ₈₆Ｓｉ₁₀₆Ｏ₃₈₄）・２６４Ｈ₂Ｏ；Ａｌ／Ｓｉ比率０．８１１、ゼオライトＹ：Ｎａ₅₆（Ａｌ₅₆Ｓｉ₁₃₆Ｏ₃₈₄）・２５０Ｈ₂Ｏ；Ａｌ／Ｓｉ比率０．４１２等が挙げられる。
【０１１９】
Ａｌ／Ｓｉ比率が０．４〜１．０である親水性の高い多孔質粒子を含有することによって親水性層自体の親水性も大きく向上し、印刷時に汚れにくく、水量ラチチュードも広くなる。また、指紋跡の汚れも大きく改善される。Ａｌ／Ｓｉ比率が０．４未満では親水性が不充分であり、上記性能の改善効果が小さくなる。粒径としては、親水性層に含有されている状態で（分散破砕工程を経た場合も含めて）、実質的に１μｍ以下であることが好ましく、０．５μｍ以下であることがさらに好ましい。粗大な粒子が存在すると親水性層表面に多孔質で急峻な突起が形成され、突起周囲にインクが残りやすくなって非画線部汚れが劣化する。多孔質粒子は親水性層全体（親水性層が光熱変換粒子を含む場合は光熱変換粒子を除いた中での）の３０〜９５質量％であることが好ましく、５０〜９０質量％であることがより好ましい。
【０１２０】
ｃ．平均粒径１００ｎｍ以下の金属酸化物微粒子
平均粒径１００ｎｍ以下の金属酸化物微粒子としては、コロイダルシリカ、アルミナゾル、チタニアゾル、その他の金属酸化物のゾルが挙げられる。金属酸化物微粒子の形態としては、球状、針状、羽毛状、その他のいずれの形態でも良い。平均粒径としては、３〜１００ｎｍであることが好ましく、平均粒径が異なる数種の金属酸化物微粒子を併用することもできる。また、粒子表面に表面処理がなされていてもよい。金属酸化物微粒子はその造膜性を利用して、結合剤としての使用が可能である。有機の結合剤を用いるよりも親水性の低下が少なく、親水性層への使用に適している。上記のなかでも特にコロイダルシリカが比較的低温の乾燥条件であっても造膜性が高く好ましい。コロイダルシリカの場合、粒子径は小さいほど結合力が強くなる。粒子径が１００ｎｍよりも大きくなると結合力は大きく低下し、結合剤として使用した場合には強度が不足する。
【０１２１】
これらの金属酸化物微粒子を多孔質シリカ粒子とともに使用する場合は、微粒子自体が陽電荷を帯びている状態で使用することが好ましく、例えば、アルミナゾルや酸性コロイダルシリカを使用することが好ましい。また、これらの金属酸化物微粒子を多孔質アルミノシリケート粒子及び／又はゼオライト粒子とともに使用する場合は、微粒子自体が陰電荷をおびている状態で使用することが好ましく、例えば、アルカリコロイダルシリカを使用することが好ましい。多孔質シリカ粒子と多孔質アルミノシリケート粒子および／またはゼオライト粒子とともに使用する場合は、例えば、表面をＡｌで処理して広いｐＨ範囲での安定性を付与したコロイダルシリカを使用することが好ましい。
【０１２２】
ｄ．新モース硬度５以上の無機粒子
多孔質ではない金属酸化物粒子（シリカ、アルミナ、チタニア、ジルコニア、酸化鉄、酸化クロム等）や金属炭化物粒子（炭化珪素等）、窒化ホウ素粒子、ダイアモンド粒子等が挙げられる。粒子は鋭角な角を有していない方が好ましく、例えば溶融シリカ粒子、シラスバルーン粒子等球形に近い粒子が好ましい。
【０１２３】
多孔質でないことの指標としては、比表面積がＢＥＴ値で５０ｍ²／ｇ以下であることが好ましく、１０ｍ²／ｇ以下であることがさらに好ましい。また、平均粒径は親水性層の層厚の１〜２倍であることが好ましく、１．１〜１．５倍であることがさらに好ましい。また粒度分布がシャープであることが好ましく、平均粒径の０．８〜１．２倍の範囲に全体の６０％以上が含まれることが好ましく、さらに、平均粒径の２倍以上の粒子が５％以下であることが好ましい。
【０１２４】
親水性層の厚さとしては、０．２〜１０μｍが好ましく、０．５〜５μｍがさらに好ましい。したがって平均粒径は０．２〜２０μｍであることが好ましく、０．５〜１０μｍであることがさらに好ましい。
【０１２５】
新モース硬度５以上の無機粒子の含有量としては、親水性層全体（親水性層が光熱変換粒子を含む場合は光熱変換粒子を除いた中での）の１〜５０質量％であることが好ましく、３〜３０質量％であることがより好ましい。
【０１２６】
ｅ．層状鉱物粒子
層状鉱物粒子としては、カオリナイト、ハロイサイト、クリソタイル、タルク、スメクタイト（モンモリロナイト、バイデライト、ヘクトライト、サボナイト等）、バーミキュライト、マイカ（雲母）、クロライトといった粘土鉱物および、ハイドロタルサイト、層状ポリケイ酸塩（カネマイト、マカタイト、アイアライト、マガディアイト、ケニヤアイト等）等が挙げられる。
【０１２７】
中でも、単位層（ユニットレイヤー）の電荷密度が高いほど極性が高く、親水性も高いと考えられる。好ましい電荷密度としては０．２５以上、さらに好ましくは０．６以上である。このような電荷密度を有する層状鉱物としては、スメクタイト（電荷密度０．２５〜０．６；陰電荷）、バーミキュライト（電荷密度０．６〜０．９；陰電荷）、マイカ（〜１；陰電荷）、ハイドロタルサイト（〜２；陽電荷）、マガディアイト（〜１；陰電荷）等が挙げられる。特に、合成フッ素雲母は粒径等安定した品質のものを入手することができ好ましい。また、合成フッ素雲母の中でも、膨潤性であるものが好ましく、自由膨潤であるものがさらに好ましい。
【０１２８】
また、上記の層状鉱物のインターカレーション化合物（ピラードクリスタル等）や、イオン交換処理を施したもの、表面処理（シランカップリング剤等）を施したものも使用することができる。
【０１２９】
平板状層状鉱物粒子のサイズとしては、親水性層中に含有されている状態で（膨潤工程、分散剥離工程を経た場合も含めて）、平均粒径（粒子の最大長）が２０μｍ以下であり、また平均アスペクト比（粒子の最大長／粒子の厚さ）が２０以上の薄層状であることが好ましく、平均粒径が１０μｍ以下であり、平均アスペクト比が５０以上であることがさらに好ましい。粒子サイズが上記範囲にある場合、薄層状粒子の特徴である平面方向の連続性および柔軟性が塗膜に付与され、クラックが入りにくく強靭な塗膜とすることができる。粒子径が上記範囲をはずれると、不必要な表面粗さの増加を伴って、非画線部の汚れやブランケット汚れが劣化する場合がある。また、アスペクト比が上記範囲以下である場合、柔軟性が不充分となり、塗膜のクラック抑制効果が低減する。層状鉱物粒子の含有量としては、親水性層全体（親水性層が光熱変換粒子を含む場合は光熱変換粒子を除いた中での）の１〜５０質量％であることが好ましく、３〜３０質量％であることがより好ましい。
【０１３０】
前記多孔質粒子及び層状鉱物粒子は分散破砕又は分散剥離して用いる。粒子の分散破砕または層剥離の方法は乾式と湿式とに大別することができる。乾式の分散破砕では乾燥工程が不要であるため工程は比較的シンプルとなるが、サブミクロンオーダーまでの分散破砕および１００ｎｍ以下の層厚までの層剥離には通常湿式の方が有利である。
【０１３１】
乾式の分散破砕装置としては、高速回転衝撃剪断式ミル（例えばアニュラータイプのイノマイザ）、気流式粉砕機（ジェットミル）、ロール式ミル、乾式の媒体攪拌ミル（例えばボールミル）、圧縮剪断型粉砕機（例えばオングミル）などが使用できる。湿式の分散破砕装置としては、湿式の媒体攪拌ミル（例えばボールミル、アクアマイザ）、高速回転式剪断摩擦式ミル（例えばコロイドミル）などが使用できる。
【０１３２】
分散破砕後の多孔質粒子の粒径は実質的に１μｍ以下であることが好ましく、０．５μｍ以下であることがさらに好ましい。また、粗大粒子が残存した場合には分級もしくはろ過により除去してもよい。
【０１３３】
また、分散破砕後の層状鉱物粒子は平均粒径（粒子の最大長）が２０μｍ以下であり、また平均アスペクト比（粒子の最大長／粒子の厚さ）が２０以上の薄層状であることが好ましく、平均粒径が１０μｍ以下であり、平均アスペクト比が５０以上であることがさらに好ましい。また、層状鉱物粒子の分散破砕の前に後述する膨潤工程を行ってもよい。
【０１３４】
特に湿式分散を行った場合は、多孔質粒子、層状鉱物粒子ともに乾燥させることなく塗布液を調製することが好ましい。分散破砕または分散剥離を行った粒子を乾燥させると再凝集を生じる場合があるためである。塗布液の固形分濃度を調整するために濃縮または希釈することは行ってもよい。
【０１３５】
さらに、上記分散破砕または分散層剥離工程において、表面処理剤を添加することで粒子に表面処理を行うこともできる。また、上記分散破砕または分散層剥離工程において、塗布液に添加する他の成分を添加して同時に分散してもよく、あるいは上記分散破砕または分散層剥離工程の後で、塗布液に添加する他の成分を添加して再度分散を行ってもよい。分散破砕または分散層剥離工程においては、メカノケミカルな反応が同時に起こっていると考えられ、塗布液に添加する他の成分と同時に分散した場合、塗膜となった際の強度向上効果が得られる場合がある。
【０１３６】
自由膨潤である膨潤性合成フッ素雲母は水と混合、攪拌するだけでも十分に膨潤し、平均厚さで１０ｎｍ以下の薄層に分断して安定した分散液となる。Ｍｇ−バーミキュライトは、例えば下記のようなイオン交換処理を行うことで膨潤性を示すようになる。
Ｍｇ−バーミキュライト＋クエン酸リチウムａｑ．→Ｌｉ−バーミキュライト＋クエン酸マグネシウムａｑ．
さらに、浸透圧で限定膨潤したＬｉ−バーミキュライトを機械的に分散・層剥離することで平均厚さ１０ｎｍ以下の薄層にまで分断することが可能となる。
【０１３７】
上記成分以外にも親水性層中には有機の結合剤または添加剤を含有させることができる。有機の結合剤としては親水性を有するものが好ましい。例えば、カゼイン、大豆タンパク、合成タンパク等のタンパク質類、キチン類、澱粉類、ゼラチン類、アルギン酸塩、ポリビニルアルコール、シリル変性ポリビニルアルコール、カチオン変性ポリビニルアルコール、メチルセルロース、カルボキシメチルセルロースやヒドロキシエチルセルロース等のセルロース誘導体、ポリエチレンオキサイド、ポリプロピレンオキサイド、ポリエチレングリコール、ポリビニルエーテル、スチレン−ブタジエン共重合体、メチルメタクリレート−ブタジエン共重合体の共役ジエン系重合体ラテックス、アクリル系重合体ラテックス、ビニル系重合体ラテックス、ポリアクリルアミド、ポリビニルピロリドン等が挙げられる。
【０１３８】
また、親水性層中にはカチオン性樹脂を含有してもよい。カチオン性樹脂としては、ポリエチレンアミン、ポリプロピレンポリアミン等のようなポリアルキレンポリアミン類またはその誘導体、第３級アミノ基や第４級アンモニウム基を有するアクリル樹脂、ジアクリルアミン等が挙げられる。カチオン性樹脂は微粒子状の形態で添加してもよい。これは、例えば特開平６−１６１１０１号に記載のカチオン性マイクロゲルが挙げられる。
【０１３９】
さらに、親水性層中には架橋剤を添加してもよい。架橋剤としては、例えば、メラミン樹脂、イソシアネート化合物、イソオキサゾール類、アルデヒド類、Ｎ−メチロール化合物、ジオキサン誘導体、活性ビニル化合物、活性ハロゲン化合物等を挙げることができる。
【０１４０】
親水性層に添加する結合剤としては、ケイ酸塩水溶液も使用することができる。ケイ酸ナトリウム、ケイ酸カリウム、ケイ酸リチウムといったアルカリ金属ケイ酸塩が好ましく、そのＳｉＯ₂／Ｍ₂Ｏ比率はケイ酸塩を添加した際の塗布液全体のｐＨが１３を超えない範囲となるように選択することが無機粒子の溶解を防止する点から好ましい。
【０１４１】
親水性層に添加する結合剤としては、いわゆるゾル−ゲル法による無機ポリマーもしくは有機−無機ハイブリッドポリマーを使用することができる。ゾル−ゲル法による無機ポリマーもしくは有機−無機ハイブリッドポリマーの形成については、例えば「ゾル−ゲル法の応用」（作花済夫著／アグネ承風社発行）に記載されているか、または本書に引用されている文献に記載されている公知の方法を使用することができる。
【０１４２】
親水性層中に含有する上記のような有機成分は、たとえ親水性の樹脂であっても耐久性、耐水性等を向上させるために架橋させた場合は親水性が大きく低下し、印刷時の汚れ原因となる。また、有機成分は多孔質粒子の開口部を塞いだり、孔中に浸透することで親水性層の多孔性を損なって保水性を低下させる可能性もある。以上の理由から有機成分の添加量は少ない方が好ましい。具体的には、好ましくは、親水性層全体（親水性層が光熱変換粒子を含む場合は光熱変換粒子を除いた中での）に対する有機成分の量が質量比で０〜５０％であり、より好ましくは１〜３０％であり、さらに好ましくは２〜２０％である。
【０１４３】
本発明の印刷版材料の基材としては、印刷版の基板として使用される公知の材料を使用することができる。例えば、金属板、プラスチックフィルム、ポリオレフィン等で処理された紙、上記材料を適宜貼り合わせた複合基材等が挙げられる。基材の厚さとしては、印刷機に取り付け可能であれば特に制限されるものではないが、５０〜５００μｍのものが一般的に取り扱いやすい。
【０１４４】
金属板としては、鉄、ステンレス、アルミニウム等が挙げられるが、比重と剛性との関係から特にアルミニウムが好ましい。アルミニウム板は、通常その表面に存在する圧延・巻取り時に使用されたオイルを除去するためにアルカリ、酸、溶剤等で脱脂した後に使用される。脱脂処理としては特にアルカリ水溶液による脱脂が好ましい。また、塗布層との接着性を向上させるために、塗布面に易接着処理や下塗り層塗布を行うことが好ましい。例えば、ケイ酸塩やシランカップリング剤等のカップリング剤を含有する液に浸漬するか、液を塗布した後、十分な乾燥を行う方法が挙げられる。陽極酸化処理も易接着処理の一種と考えられ、使用することができる。また、陽極酸化処理と上記浸漬または塗布処理を組合わせて使用することもできる。また、公知の方法で粗面化されたアルミニウム板を使用することもできる。
【０１４５】
プラスチックフィルムとしては、ポリエチレンテレフタレート、ポリエチレンナフタレート、ポリイミド、ポリアミド、ポリカーボネート、ポリスルホン、ポリフェニレンオキサイド、セルロースエステル類等を挙げることができる。特にポリエチレンテレフタレート、ポリエチレンナフタレートが好ましい。これらプラスチックフィルムは塗布層との接着性を向上させるために、塗布面に易接着処理や下塗り層塗布を行うことが好ましい。易接着処理としては、コロナ放電処理や火炎処理、紫外線照射処理等が挙げられる。また、下塗り層としては、ゼラチンやラテックスを含む層等が挙げられる。
【０１４６】
また、複合基材としては、上記材料を適宜貼り合わせて使用するが、親水性層を形成する前に貼り合わせてもよく、また、親水性層を形成した後に貼り合わせてもよく、印刷機に取り付ける直前に貼り合わせてもよい。
【０１４７】
本発明を湿し水不要印刷版材料に適用したときの画像形成方法について、インキ反撥性シリコーン含有層、光熱変換層及び基材の順に構成した印刷版材料の場合を例に説明するがこれに限るものではない。
【０１４８】
露光による発熱により、光熱変換層の全部もしくは一部がアブレートするか、またはシリコーン含有層と光熱変換層との界面の結合が切断される。露光部のシリコーン層はアブレートの衝撃で剥離している（部分的には亀裂が生じ、一部が飛散している場合もある）ため、比較的弱い物理的な力で除去可能となる。光熱変換層及び／又は基材表面をインク受容性としておくことで、露光部が画像となる。
【０１４９】
露光部のシリコーン含有層の除去方法としては、適等な処理液を含ませた布で拭き取る、適等な処理液中で回転ブラシでこする等して除去する、印刷機上での印刷初期の段階で各種ローラーとの接触及び／又は離脱の力によって除去するといったことが挙げられる。
【０１５０】
湿し水を使用する印刷版の作製に本発明の光熱変換粒子を含有する親水性層を有する印刷版材料を用いる場合、以下のような方法により画像を形成することができるが、これに限るものではない。
【０１５１】
本発明の光熱変換粒子を含有する親水性層の上に公知のインクジェット法によりインキ受容素材を画像様に付着させて画像層を形成する。該インキ受容素材は耐水性を有するものである。該インキ受容要素はホットメルトや画像形成後に熱または光で硬化する熱硬化性物質または光硬化性物質でもよい。
【０１５２】
熱硬化性物質の例としては、ハロゲン化ビスフェノール、レゾルシン、ビスフェノールＦ、テトラヒドロキシフェニルエタン、ノボラック、ポリヒドロキシ化合物、ポリグリコール、グリセリントリエーテル、ポリオレフィン、エポキシ化大豆油、ビニルシクロヘキセンジオキシド、エポキシ化大豆油と有機酸又はその無水物（例、フタル酸、マレイン酸、セバシン酸又はその無水物）、あるいは有機過酸化物（例、過酸化ベンゾイルまたは過酸化フタロイド）との組み合わせ、ジアリルオルソフタレート、ジアリルイソフタレート又はジアリルクロレンテート、あるいはこれらと有機化酸化物（例、過酸化ベンゾイルまたは過酸化フタロイド）との組み合わせ、Ｎ−メチル−Ｎ′−メチロールウロンエチルエーテル、Ｎ−メチル−Ｎ′−エチロールウロンエチルエーテル、Ｎ−エチル−Ｎ′−メチロールウロンメチルエーテル、テトラメチロールウレア、Ｎ−メチル−Ｎ，Ｎ′，Ｎ′−トリメチロールウレア、Ｎ−エチル−Ｎ，Ｎ′，Ｎ′−トリメチロールウレア、Ｎ，Ｎ′−ジエチル−Ｎ，Ｎ′−ジメチロールウレア、モノ及びポリメチロールメラミン、ｐ−メチロールフェノール、フェノール、ｏ−メチロールフェノール、２，４−ジメチロールフェノールあるいは２，６−ジメチロールフェノールとホルムアルデヒドとの組み合わせ、アニリン樹脂、キシレン樹脂、不飽和ポリエステル樹脂、及びフラン樹脂を挙げることができる。
【０１５３】
光硬化性物質としては、不飽和ポリエステル（二塩基酸の例：無水マレイン酸、フマル酸、イタコン酸、コハク酸、アジピン酸、アゼライン酸、セバシン酸、無水フタル酸、テトラヒドロ無水フタル酸、ヘキサヒドロ無水フタル酸、イソフタル酸、テレフタル酸、無水トリメリット酸及び無水ピロメリット酸；多価アルコールの例：エチレングリコール、プロピレングリコール、２，３−ブタンジオール、１，３−ブタンジオール、ネオペンチルグリコール、１，４−ブタンジオール、ジエチレングリコール、ジプロピレングリコール、トリエチレングリコール、グリセリントリメチロールプロパン、ポリエチレングリコール、ポリプロピレングリコール）；及びアクリレートまたはメタクリレートモノマー又はオリゴマー（例：メトキシジエチレングリコールメタクリレート、メトキシテトラエチレングリコールメタクリレート、メトキシジエチレングリコールアクリレート、メトキシポリエチレングリコールアクリレート、メトキシポリエチレングリコールメタクリレート、２−ヒドロキシドデシルメタクリレート、２−ヒドロキシドデシルアクリレート、トリエチレングリコールジメタクリレート、ジエチレングリコールジメタクリレート、エチレングリコールメタクリレート、ポリエチレングリコールジメタクリレート、１，３−ブチレングリコールジメタクリレート、１，４−ブチレングリコールジメタクリレート、１，６−ヘキサングリコールジメタクリレート、ネオペンチルグリコールジメタクリレート、ジプロピレングリコールジメタクリレート、ポリプロピレングリコールジメタクリレート、２，２−ビス（４−メタクリロキシジエトキシフェニル）プロパン、ジエチレングリコールジアクリレート、ポリエチレングリコールジアクリレート、１，３−ブチレングリコールジアクリレート、１，６−ヘキサングリコールジアクリレート、ネオペンチルグリコールジアクリレート、ポリプロピレングリコールジアクリレート、２，２′−ビス（４−アクリロキシプロピロキシフェニル）プロパン、２，２′−ビス（４−アクリロキシジエトキシフェニル）プロパン、トリメチロールプロパントリメタクリレート、トリメチロールエタントリメタクリレート、トリメチロールプロパントリアクリレート、トリメチロールエタントリアクリレート、トリメチロールメタントリアクリレート、トリメチロールプロパンジアクリレートモノヤシ油脂肪酸エステル、テトラメチロールメタンテトラアクリレート、ジブロムネオペンチルグリコールジメタクリレート、及び２，３−ジブロムプロピルアクリレート）。上記光硬化性物質は、一般に光重合開始剤と共に使用される。光重合開始剤の例としては、ベンゾフェノン等の芳香族ケトン類、アセトフェノン類、ジケトン類及びアシルオキシムエステル類等を挙げることができる。
【０１５４】
また、公知の感熱転写法によりインク受容性の感熱転写層を有するシートの感熱転写層を親水性層表面に密着させ、シート側からサーマルヘッドもしくはレーザー光によって画像様に加熱して、加熱部分の感熱転写層をシートから親水性層表面に転写した後、シートを取り去ることで画像層を形成する。
【０１５５】
公知の光硬化性または光可溶性の感光層を親水性層上に塗設し、露光後、可溶部分を現像により除去して画像層を形成する。
【０１５６】
公知の熱（赤外線）硬化性または熱（赤外線）可溶性の感光層を親水性層上に塗設し、レーザー露光後、可溶部分を現像により除去して画像層を形成する。
【０１５７】
融点が１００℃前後の熱溶融性微粒子（例えばポリエチレンワックスエマルジョン）を適当な水溶性バインダやコロイダルシリカ等をバインダとして親水性層上に塗説し、レーザー露光により熱溶融性微粒子を溶融して親水性層中に浸透させて画像部とし、未露光部は水洗により除去するかもしくは印刷機上で湿し水で溶解させて除去する。
【０１５８】
本発明の画像形成材料は、基材上のいずれかの層に露光可視画性を示すような素材を添加することができる。露光可視画性の付与には、例えば、感熱紙に使用されている公知の技術を適用することができる。
【０１５９】
本発明の画像形成材料は、近赤外線レーザーによる露光が好ましい。露光装置としてはサーマルＣＴＰ用の一般的な露光機が使用できる。露光エネルギーは１００〜５００ｍＪ／ｃｍ²が好ましい。
【０１６０】
以上は、印刷版用材料である本発明を説明した。本発明に係る光熱変換粒子は、レーザー光などの光を照射し、その光エネルギーを光熱変換材によって熱エネルギーに変換し、画像の形成を行う画像形成材料全てに適用してもよい。印刷版用材料以外の画像形成材料としては、以下のような例がある。
【０１６１】
光熱変換層とインク層とを有するレーザー熱転写用インクシートと、熱可塑性樹脂層と受像層とを有するレーザー熱転写用受像シートとを、インクシートのインク層と、受像シートの受像層とを重ねて、レーザー光を画像様に照射し、インク層を受像層側に熱転写した後に、インクシートを受像シートから剥離することによって画像を形成するレーザー熱転写記録材料が、画像形成材料の１例として挙げられる。この場合、インクシートの光熱変換層に本発明の光熱変換粒子を含有させるものである。
【０１６２】
他の画像形成材料としては、支持体上に色剤（色素や色を有する粒子など）を有する画像形成層を有し、像様にレーザーを照射することにより、画像形成層のレーザーを照射された部分がアブレートし、画像を形成するアブレーション画像形成材料が挙げられる。この場合、画像形成層に本発明の光熱変換粒子を含有させてもよいし、画像形成層とは別に光熱変換層を設け、その光熱変換層に本発明の光熱変換粒子を含有させてもよい。
【０１６３】
【実施例】
次に、本発明を実施例により更に具体的に説明するが本発明は以下の実施例に限定されるものではない。
【０１６４】
（光熱変換粒子の製造）
表１〜表２に示す芯材粒子の表面をサンドグラインダーとガラスビーズ（ハイビー２０）を用いた乾式法により光熱変換材及びその他の素材で被覆した。ディスクの回転数は８００ｒｐｍとした。被覆粒子懸濁液の組成（芯材粒子、被覆素材及び分散媒）及び処理時間を表１〜表２に示す。処理終了後、光熱変換粒子をサンプリングし、ＳＥＭ観察によって芯材粒子の表面被覆率を評価した。この結果も表１〜表２に示す。
【０１６５】
また、被覆した光熱変換粒子は、サンドグラインダーにさらにプロピレングリコールモノメチルエーテルアセテートもしくは純水を加えて攪拌し、ガラスビーズと分離して、１０質量％の懸濁液として回収した。
【０１６６】
【表１】

【０１６７】
【表２】

【０１６８】
実施例１、比較例１（湿し水不要印刷版）
実施例１−１〜１−６
表３〜表４に示す組成の光熱変換粒子を含有する光熱変換層塗布液を調製し、基体として厚さ０．１８ｍｍのポリエチレンテレフタレートフィルムにコロナ放電を施した面にワイヤーバーを用いて塗布し、８０℃で５分間乾燥し、光熱変換層を設けた。塗布量は乾燥後で１．５ｇ／ｍ²とした。
【０１６９】
比較例１−１
下記組成の分散液を調製し、プラネタリーミキサーで１時間混合した後、３本ロールミルを１４回通過させて、前分散処理とした。その後、固形分濃度を同一の溶剤で３０質量％に調整し、サンドグラインダーで１ｍｍφのジルコニアビーズを用いて３時間分散処理を行い、さらに固形分濃度を同一の溶剤で１０質量％に調整して光熱変換層塗布液とし、実施例１と同様にして厚さ０．１８ｍｍのポリエチレンテレフタレートフィルム上に塗布、乾燥した。
【０１７０】
分散液
チタンブラック１３Ｍ（三菱マテリアル社製） １５質量部
ニトロセルロース ３５質量部
プロピレングリコールモノメチルエーテルアセテート ５０質量部
比較例１−２
比較例１−１の分散液組成のチタンブラック１３Ｍの量を２０質量部、ニトロセルロースの量を３０質量部に変えた以外は比較例１−１と同様にしてポリエチレンテレフタレートフィルム上に光熱変換層を設けた。
【０１７１】
上記各光熱変換層の上に、さらに下記組成のシリコーン含有層塗布液を塗布し、１００℃で３分間乾燥して湿し水不要印刷版材料を得た。塗布量は乾燥後で１．０ｇ／ｍ²とした。
【０１７２】
シリコーン含有層塗布液
両末端に水酸基をポリジメチルシロキサン（Ｍｗ８００００） ９３ｇ
３−［Ｎ−アリル−Ｎ−（２−アミノエチル）］
アミノプロピルトリメトキシシラン ６．３ｇ
ジブチル錫ジラウリレート ０．７ｇ
アイソバーＥ（エクソン化学社製） ９００ｇ
得られた湿し水不要印刷版材料を、シリコーン含有層を外側にしてレーザー露光機のドラムに巻きつけ、８３０ｎｍの赤外線レーザーで４０００ｄｐｉの解像度（レーザービーム径６μｍ）で露光エネルギー量を変化させて画像様に露光した。露光後、印刷版のシリコーン含有層表面を水を含ませた柔らかい布で拭き、露光部に残存していたり、その周囲に飛散しているアブレーションしたシリコーン含有層を除去した。そして、以下の方法で感度及び解像度を評価した。その結果を表３〜表４に示す。
【０１７３】
感度評価方法
印刷機として三菱重工業（株）製ＤＡＩＹＡ１Ｆ−１を用い、コート紙、湿し水不要平版印刷版用インキ（東洋インキ（株）製アクワレスエコーＭ紅）を使用して印刷を行った。目視判断でかすれのない良好な印刷画像が得られた最低の露光エネルギー量を感度とした。
【０１７４】
解像度評価方法
上記で感度として示した露光エネルギー量に対応する紙面上の画像細線部を顕微鏡観察し、途切れること無く再現している細線幅と、その細線エッジのシャープさを評価した。
【０１７５】
【表３】

【０１７６】
【表４】

【０１７７】
実施例２、比較例２（湿し水使用印刷版）
下塗り層の形成
基材として厚さ０．１８ｍｍのポリエチレンテレフタレートフィルムを用い、以下の方法により２層からなる下塗り層を形成した。
【０１７８】
第一下塗り層
ポリエチレンテレフタレートフィルム基材の塗布面にコロナ放電処理を施した後、下記組成の第一下塗り層塗布液を、２０℃、相対湿度５５％の雰囲気下でワイヤーバーにより乾燥後の膜厚が０．４μｍとなるように塗布し、１４０℃で２分間乾燥を行った。
【０１７９】
第一下塗り層塗布液
アクリルラテックス粒子（ｎ−ブチルアクリレート／
ｔ−ブチルアクリレート／スチレン／ヒドロキシエチルメタクリレート
＝２８／２２／２５／２５） ３６．９ｇ
界面活性剤（Ａ） ０．３６ｇ
硬膜剤（ａ） ０．９８ｇ
以上に蒸留水を加えて１０００ｍｌとし、塗布液とした。
【０１８０】
第二下塗り層
上記フィルムの第一下塗り層を形成した面にコロナ放電処理を施した後、下記組成の第二下塗り層塗布液を、３５℃、相対湿度２２％の雰囲気下でエアーナイフ方式により乾燥後の膜厚が０．１μｍとなるように塗布し、１４０℃で２分間乾燥を行った。
【０１８１】
第二下塗り層塗布液
ゼラチン ９．６ｇ
界面活性剤（Ａ） ０．４ｇ
硬膜剤（ｂ） ０．１ｇ
以上に蒸留水を加えて１０００ｍｌとし、塗布液とした。
【０１８２】
【化１０】

【０１８３】
光熱変換粒子を含有する層及び画像形成層（１）の形成
実施例２−１〜２−９、比較例２−１〜２−７
光熱変換粒子の水懸濁液を含む表５〜表１１に示した組成及び分散方法で光熱変換層塗布液を調製し、表１２に示した塗布量となるように下塗り層形成済みのポリエチレンテレフタレートフィルムにワイヤーバーで塗布し、１００℃で５分間乾燥した。表６に第二層塗布の記載があるものには光熱変換層の上にさらに表１２に示した塗布量となるように塗布して、１００℃で５分間乾燥した。
【０１８４】
さらに下記組成の画像形成層（１）塗布液を、光熱変換層の上にワイヤーバーを用いて塗布し、７０℃で３分間乾燥した。塗布量は１．０ｇ／ｍ²とした。
【０１８５】

上記に純水を加えて固形分濃度を１０．０質量％とした。
【０１８６】
得られた印刷版材料を、画像形成層を外側にしてレーザー露光機のドラムに巻きつけ、８３０ｎｍの赤外線レーザーで４０００ｄｐｉ（２４．５ｍｍ当たり何ドットのものをｄｐｉと称する）の解像度（レーザービーム径６μｍ）で露光エネルギー量を変化させて画像様に露光した。
【０１８７】
レーザー露光時のアブレーションの有無の評価
露光後の印刷版の画像部をＳＥＭ観察し、アブレーションが発生し始める最低露光エネルギー量を求めた。
【０１８８】
感度評価方法
印刷機として三菱重工業（株）製ＤＡＩＹＡ１Ｆ−１を用い、コート紙、湿し水（東京インキ（株）製Ｈ液ＳＧ−５１ 濃度１．５％）、インキ（東洋インキ（株）製トーヨーキングハイエコーＭ紅）を使用して印刷を行った。目視判断でかすれのない良好な印刷画像が得られた最低の露光エネルギー量を感度とした。その結果を表１３に示す。
【０１８９】
解像度評価方法
上記で感度として示した露光エネルギー量に対応する紙面上の画像細線部を顕微鏡観察し、途切れること無く再現している細線幅と、その細線エッジのシャープさを評価した。結果を表１３に示す。
【０１９０】
【表５】

【０１９１】
【表６】

【０１９２】
【表７】

【０１９３】
【表８】

【０１９４】
【表９】

【０１９５】
【表１０】

【０１９６】
【表１１】

【０１９７】
【表１２】

【０１９８】
【表１３】

【０１９９】
光熱変換粒子を含有する層及び画像形成層（２）の形成
実施例３−１〜３−４、比較例３−１〜３−４
光熱変換粒子の水懸濁液を含む表５〜表１１に示した組成及び分散方法で光熱変換層塗布液を調製し、表１４に示した塗布量となるように下塗り層形成済みのポリエチレンテレフタレートフィルムにワイヤーバーで塗布し、１００℃で５分間乾燥した。さらに下記のような画像形成層（２）塗布液を調製し、光熱変換層の上にワイヤーバーを用いて塗布し、７０℃で３分間乾燥した。塗布量は０．６ｇ／ｍ²とした。
【０２００】

上記に純水を加えて固形分濃度を１０．０質量％とした。
【０２０１】
実施例２と同様にしてレーザー露光し、画像形成を行い、アブレーション、感度及び解像度の評価を行った。また、下記の方法で擦り傷耐性を評価した。その結果を表１５に示す。
【０２０２】
擦り傷耐性評価方法
耐摩耗性試験機（ＨＥＩＤＯＮ−１８）を用い、０．１ｍｍφの触針で５０、１００、１５０、２００ｇと荷重を変化させて、画像形成後の印刷版非画像部表面を摺動させ、印刷時に汚れとして確認される摺動傷が何ｇの荷重で付けられたものであるか評価した。
【０２０３】
【表１４】

【０２０４】
【表１５】

【０２０５】
【発明の効果】
本発明によれば、高感度、高解像度でかつ耐摩耗性が高く傷による汚れの発生しないヒートモード記録が可能な画像形成材料及びそれに用いる光熱変換材（光熱変換粒子）並びに該画像形成材料の製造方法が提供され、さらに、画像形成材料の構成層の耐水性も向上させることが可能となる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming material for forming an image by converting infrared laser light irradiated like an image into heat by a photothermal conversion material, a photothermal conversion material used therefor, and a method for producing the image forming material. The present invention relates to improvement of a photothermal conversion material.
[0002]
[Prior art]
In recent years, with the progress of digital image processing technology using a semiconductor laser and a computer, a technique (CTP) for producing a lithographic printing plate by directly scanning a PS plate with a semiconductor laser from digital image data formed by a computer with a semiconductor laser has attracted attention. ing. Along with the digitization of such print data, there is a need for a CTP that is inexpensive, easy to handle, and has the same printability as the PS plate. In recent years, various types of CTP using infrared laser recording have been proposed. Among them, so-called dry CTP (including development on a printing press) that does not require special development processing has attracted attention. Examples of such a technique include the following.
[0003]
JP-A-8-507727 discloses a heat mode recording having a recording layer containing a photothermal conversion substance and a dura hydrophilic surface layer containing a photothermal conversion substance on a support having an ink receptive surface. A material and a method for forming an image by removing a layer above the recording layer by ablation by laser with a material are disclosed.
[0004]
In JP-A-6-186750, a plate having a first layer and a second layer having different affinity for ink or an ink adhesion preventing liquid is scanned with an infrared laser, and one or more of these layers are ablated. A method and apparatus for removing and forming an image is disclosed.
[0005]
In JP-A-6-199064, an upper layer first layer which is an infrared absorption layer and a second layer which is a lower layer thereof are provided on a substrate, or an upper layer first layer and an infrared absorption layer which is a lower layer thereof. There is disclosed a lithographic printing plate material for laser recording, which has a second layer, the first layer and the second layer have different affinity for ink or an ink adhesion preventing liquid, and forms an image by ablation .
[0006]
Japanese Patent Application Laid-Open No. 7-314934 has a top layer that is not ablated, a titanium or titanium alloy thin layer metal layer that is ablated, and a substrate, and the top layer and the substrate have different affinity for ink or ink insoluble fluid. A laser recording printing member exhibiting properties and a method of forming an image by ablation are disclosed.
[0007]
Japanese Patent Application Laid-Open No. 10-58636 has a laser-sensitive hydrophilic swelling layer (preferably containing a color pigment or a black dye) on a substrate, and the hydrophilic swelling layer is removed by ablation by laser irradiation. A lithographic printing plate precursor for forming a solid image is disclosed.
[0008]
In the heat mode laser recording printing plate material containing the above, uniform dispersion of the photothermal conversion substance in the layer becomes a problem, and the sensitivity and resolution may be lowered. In particular, a conductive metal oxide (for example, titanium black) is difficult to disperse in a coating solution alone, and aggregates to easily reduce sensitivity and resolution.
[0009]
By the way, in any of the above systems, any layer formed on the substrate has a photothermal conversion function, and the layer having the photothermal conversion function is formed by coating a layer in which a photothermal conversion material is mixed and / or dispersed. It is common. The amount of the photothermal conversion material in the layer and the degree of dispersion are closely related to the sensitivity during laser exposure. When an infrared absorbing dye that is soluble in the solvent of the coating solution that forms the layer is used as the photothermal conversion material, the dispersion is good and the sensitivity to the amount added is high, but the cost increases because the infrared absorbing dye is very expensive. It becomes. In addition, when a water-soluble pigment is added to the aqueous layer, the water resistance of the coating film is deteriorated, so that it is difficult to apply it to a printing plate using a fountain solution.
[0010]
In the case of using a solid particulate photothermal conversion material, if the degree of dispersion is poor, it is necessary to relatively increase the amount of addition in order to obtain the desired sensitivity. However, there is a problem that the resolution is poor or the physical properties of the coating film are deteriorated and the required strength as a printing plate cannot be obtained.
[0011]
Among solid particulate light-to-heat conversion materials, conductive metal oxides are preferable as materials used for printing plates due to various characteristics. For example, titanium black is very difficult to disperse in paints, and a method for improving dispersion Was desired.
[0012]
As one of such examinations, Japanese Patent Application Laid-Open No. 10-244773 discloses that titanium black contained in a layer having a photothermal conversion function is a layer having a particle size of 0.1 μm or more and 2.0 μm or less with 50% or more of the total amount. Although it is proposed to disperse in the inside, the actual method for reaching this state is to perform a kneading process such as a three-roll or kneader before the dispersion process using beads. The cost of the dispersion process is unavoidable. Furthermore, the use of titanium black having a primary particle size of several tens of nanometers in a dispersed state with a particle size of 0.1 to 2.0 μm means that the photothermal conversion efficiency per unit addition amount is improved. hard.
[0013]
In particular, a printing plate material configured to form an image without ablating a layer having a photothermal conversion function does not scatter a substance ablated at the time of laser exposure. Although it has a great advantage that it does not contaminate, when a photothermal conversion material having a particle size of 2 μm as described above is contained in the layer having the photothermal conversion function of the printing plate material having such a configuration, only local heat generation is caused. As a result, the vicinity of the light-to-heat conversion material particles is ablated, and the temperature of the entire layer does not increase, and the sensitivity decreases.
[0014]
In addition, the printing plate surface formed with the coating layer may have insufficient strength, and scratches due to scratches appear as stains during printing, which often causes problems.
[0015]
In addition to the above-described lithographic printing plate, an image forming material that forms an image by converting infrared laser light irradiated like an image into heat by the light-to-heat conversion material is accompanied by the fact that the light-to-heat conversion material is not uniformly dispersed. However, there are problems such as a reduction in sensitivity and resolution, and generation of ablation due to local heat generation.
[0016]
[Problems to be solved by the invention]
An object of the present invention is to provide an image forming material (for example, a printing plate material, a laser thermal transfer recording material, etc.) having high sensitivity, high resolution, high wear resistance, and capable of heat mode recording that does not generate dirt due to scratches, and the like. The object is to provide a photothermal conversion material and a method for producing the image forming material.
[0017]
[Means for Solving the Problems]
The configuration of the present invention for achieving the above object is as follows.
[0031]
  (1)A printing plate having a layer containing photothermal conversion particles in which a core material surface is coated on a base material with a material containing a photothermal conversion materialmaterial.
  (2) The above (where the photothermal conversion material is a conductive metal oxide (1)Print versionmaterial.
[0032]
  (3) The above (where the core material is organic particles)1Or2)Print versionmaterial.
[0033]
  (4) The above (where the average particle size of the photothermal conversion particles is 0.1 to 10 μm)1) ~ (3)Print versionmaterial.
[0034]
  (5) The surface coverage of the photothermal conversion particles by the material containing the photothermal conversion material is 20% or more in terms of the area (1) ~ (4)Print versionmaterial.
[0035]
  (6) On the substrate,A photothermal conversion particle containing a material containing a core material and a photothermal conversion material, the surface of the core material being coated with a material containing the photothermal conversion materialIncluding a step of forming a layer by applying a liquid containing at least photothermal conversion particlesA printing plate having a layer containing photothermal conversion particlesA method for producing a material, wherein a core material is coated with a material containing a photothermal conversion material by a dry dispersion method or a spray drying method.Print versionMaterial manufacturing method.
[0036]
The present inventor has made various studies on the above problems, and by adding particles in which the photothermal conversion material is thinly coated on the surface of the core material in the layer having the photothermal conversion function, the photothermal conversion material in the layer is added. It is found that it is possible to give a very efficient photothermal conversion function to the amount, and when used for a printing plate material configured to form an image without ablating a layer having a photothermal conversion function, It was confirmed that no ablation occurred within the practical sensitivity range. In addition, with respect to this problem, by selecting particles having relatively high hardness or toughness as the core material, and mixing particles with a photothermal conversion material coated on the surface thereof in a high density, high sensitivity can be obtained. It was found that the effect of preventing scratches can be obtained while maintaining the same. In particular, it has also been found that when organic particles coated with a conductive metal oxide are blended, the surface hardness is hard and the particles are tough, so that the effect of preventing scratches is further improved.
[0037]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
[0038]
First, the photothermal conversion particle | grains which coat | covered the core material surface of this invention with the raw material containing a photothermal conversion material, and the layer containing this particle | grain are demonstrated.
[0039]
In the present invention, any of the following inorganic particles and organic particles can be used as the core material of the photothermal conversion particles. Two or more kinds of particles made of different kinds of materials can be used in combination.
[0040]
As the inorganic particles, general metal oxide particles such as silica, alumina, aluminosilicate, titania and zirconia can be used. However, since sedimentation occurs when added and dispersed in the coating solution, porous particles having an apparent specific gravity of 1.5 or less are preferable. In addition, when the degree of porosity is too high, the strength of the particles decreases and the wear resistance deteriorates. Therefore, the oil absorption amount of the particles is preferably in the range of 40 to 100 ml / 100 g. The shape is preferably close to a sphere. Examples of such porous particles include porous silica particles and porous aluminosilicate particles.
[0041]
As the organic particles, general crosslinked resin particles such as nylon, PMMA, silicone, Teflon, polyethylene, and polystyrene can be used. Calcium alginate particles can also be used. When the organic material is used as the core material, the photothermal conversion particles coated with the core material may be generated using a so-called microcapsule forming method.
[0042]
The particles can be used as they are, but can also be used after surface treatment with a coupling agent, a sol such as iron sol or tin sol, or a known surface treatment agent. The average particle diameter is preferably 0.1 to 19 μm, more preferably 0.5 to 6 μm as primary particles. Two or more kinds of particles having different average particle diameters can be used in combination.
[0043]
90% or more is preferable with respect to the thickness of 1 micrometer of raw materials, and, as for the infrared transmittance of a core material, it is more preferable that it is 95% or more. This is because when the core material has an infrared absorption ability, the effect of coating the core material with the photothermal conversion material and substantially dispersing it is not obtained.
[0044]
In this specification, the photothermal conversion material means a substance capable of converting light into heat. Since the image forming material of the present invention (for example, printing plate material, laser thermal transfer recording material, etc.) is image-recorded with infrared rays, the photothermal conversion material used for the photothermal conversion particles has a function of converting infrared rays into heat, that is, red. Materials that have external absorption can be used. Examples of the material include general infrared absorbing dyes (for example, cyanine and phthalocyanine). However, there is a problem that the water resistance and durability of the layer are reduced when a water-soluble dye is added to the porous layer. When a water-insoluble dye is added, the solid dye is added to the aqueous dispersion in the form of ultrafine particles. It is difficult to uniformly disperse the dye, and the agglomerated dye has poor photothermal conversion efficiency, and also has the problem of causing stains during image formation and printing. However, such a pigment can be dissolved or dispersed in a solvent together with an appropriate binder and coated on the surface of the core material particles by a spray drying method described later.
[0045]
Among the photothermal conversion materials having absorption in the red exterior, the photothermal conversion material itself is preferably a conductive material. The photothermal conversion material may be a semiconductor. The reason is not clear, but when the photothermal conversion material has electrical conductivity, the ink adhesion to the non-image area is remarkably improved, especially in the printing plate material using fountain solution, and the stain recovery is greatly improved. Is done. Examples of such materials include metals, conductive carbon, graphite, and conductive metal oxides. Among these, a conductive metal oxide is particularly preferable.
[0046]
As the metal, any metal can be used as long as the particle diameter is 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less. The shape may be any shape such as a spherical shape, a piece shape, or a needle shape. Colloidal metal fine particles (Ag, Au, etc.) are particularly preferable.
[0047]
As the conductive carbon, furnace black or acetylene black is particularly preferable. Particle size (d₅₀) Is preferably 100 nm or less, and more preferably 50 nm or less. Further, the conductivity index represented by the following formula is preferably 30 or more, and more preferably 50 or more.
[0048]
Conductivity index = {specific surface area (m²/ G) × DBP oil absorption (ml / 100 g)}^1/2/ (1 + volatile)
As the graphite, fine particles having a particle size of 0.5 μm or less, preferably 100 nm or less, more preferably 50 nm or less can be used.
[0049]
These metal fine particles, carbon fine particles, and the like can be similarly coated on the surface of the core material particles by spray drying.
[0050]
Examples of conductive (or semiconductor) metal oxides include ZnO, ZnO doped with Al, and SnO.₂SnO doped with Sb₂(ATO), In with Sn added₂O_Three(ITO), TiO₂TiO₂And TiO (titanium oxynitride, generally titanium black) reduced. These metal oxides can also be used as a core material (BaSO_FourTiO₂, 9Al₂O_Three2B₂O, K₂OnTiO₂Etc.) can also be used. These particle sizes are 0.5 μm or less, preferably 100 nm or less, and more preferably 50 nm or less. These can be similarly coated on the surface of the core material particles by spray drying, but can also be fixed and / or coated on the surface of the core material particles by physical encroachment or electrostatic adsorption by a dry method. .
[0051]
When the layer having a photothermal conversion function is used as a non-image-portion hydrophilic layer of a printing plate of a type that uses fountain solution, it is particularly preferable to use a conductive metal oxide as the photothermal conversion material. By including a conductive metal oxide in the hydrophilic layer, the polar component in the layer is increased and the hydrophilicity is improved.
[0052]
In the present invention, two or more photothermal conversion materials can be used in combination, and the photothermal conversion material can be used by being added to the binder in the layer in addition to the coating of the core material particles. .
[0053]
In the present invention, the material containing the photothermal conversion material (hereinafter sometimes referred to as “coating material”) is the photothermal conversion material itself or the photothermal conversion material and other coating materials (for example, binders, additives, etc.). It means a mixture.
[0054]
In the present invention, in order to coat the core material surface with a material containing a photothermal conversion material, it is possible to coat using a general method of forming microcapsules. For example, various methods described in "Microcapsules-its production, properties, and applications" (1985 Sankyo Publishing Co., Ltd.) written by Tamotsu Kondo and Masumi Koishi can be used. However, it is not limited to this. Among them, the following methods are suitable.
[0055]
Spray drying method
Prepare a dispersion of the photothermal conversion material to be used. At this time, a binder and a solvent are appropriately selected. In the dispersing step, a normal kneading and dispersing method can be used. This method is highly efficient because only the coating content is dispersed, and there is also an advantage that a different binder or solvent from that required for the layer exhibiting the intended function can be used. For example, the coated particles to be added to the solvent-based coating layer may be prepared with an aqueous dispersion. The core particles are uniformly suspended in this dispersion and spray-dried to obtain coated particles. This step can be performed using, for example, a commonly used spray-dry granulator. The concentration of the photothermal conversion material dispersion is preferably from 0.1 to 10% by mass, and the suspension concentration of the core material particles is preferably from 10 to 50% by mass.
[0056]
Dry dispersion method
In this method, the core material particles and the coating material are collided to fix the coating material on the surface of the core material by electrostatic force or physical biting. In this method, it is preferable that the core particles themselves are not crushed by physical impact, and is particularly suitable when organic particles such as nylon, PMMA, silicone, and Teflon are used as the core material.
[0057]
The coating can be performed using a dispersing machine such as a sand grinder or a ball mill. In addition, it is preferable to use a device such as a hybridizer manufactured by Nara Machinery Co., Ltd., which is a high-speed air-flow impact method that does not use dispersed beads, because the coated particles can be easily recovered. In the case of using dispersed beads (glass, ceramic, etc.), for example, the coating is performed at a rotational speed of 300 to 2000 rpm and a processing time of 5 to 60 minutes. When a hybridizer is used, coating is performed at a peripheral speed of 50 to 150 m / sec and a processing time of 1 to 20 minutes.
[0058]
In the present invention, the surface coverage by the coating material (including the photothermal conversion material and other binders and additives, including those) is preferably 20% or more in area. Here, the surface coverage is defined as the ratio of the area of the coating material covering the core particle surface to the surface area calculated by regarding the core as a sphere. Moreover, it is preferably 5 to 100% by mass, and more preferably 10 to 60% by mass with respect to the total mass of the coated particles (that is, photothermal conversion particles).
[0059]
In the particle coating by the dry method, the average surface coverage is preferably 50% or more, and more preferably 80% or more. The amount of the photothermal conversion material contained in the entire layer is preferably 1 to 50% by mass, more preferably 5 to 20% by mass.
[0060]
In the present invention, the average particle diameter of the photothermal conversion particles is preferably in the range of 0.1 to 10 μm. In addition to containing the light-to-heat conversion material as light-to-heat conversion particles covering the surface of the core material, the light-to-heat conversion material may be simply added to the binder, and in this case, the degree of dispersion of the light-to-heat conversion material is higher. preferable.
[0061]
The layer (photothermal conversion layer) containing the photothermal conversion particles of the present invention can use a known organic, inorganic, or organic-inorganic composite binder as a binder component. The optimum binder varies depending on the type (need / unnecessity of fountain solution) and layer structure.
[0062]
The content of the photothermal conversion particles in the photothermal conversion layer is preferably in the range of 20 to 90% by mass, more preferably in the range of 40 to 80% by mass with respect to the photothermal conversion layer.
[0063]
  Of the present inventionPrinting plate material (hereinafter also referred to as image forming material)As one preferable form, there is a form having a layer having a function of forming an image by light or heat in addition to the layer containing the photothermal conversion particles. As such a form, a layer containing photothermal conversion particles is a hydrophilic layer, and a layer having a function of forming an image by light or heat, fine particles having a property of being melted and fused by ink-accepting heat, For example, the form made into the particle layer formed with the wax emulsion is mentioned. In the particle layer, the particles are fused by imagewise heating, and the particle layer in the non-fused portion is removed to expose the hydrophilic layer and form a plate surface. In addition, there is a method of forming an image layer by adhering an ink receiving material imagewise to the surface of a layer containing photothermal conversion particles by a known ink jet method. As the image forming material (ink) used in the inkjet method, a material that can be cured by light or heat after image formation is used.WhenIs preferred. There are also image forming materials used for image formation by hot melt transfer.
[0064]
The image forming material of the present invention may have an image forming layer separately from the constituent layer containing the photothermal conversion particles of the present invention (photothermal conversion layer), or the constituent layer containing the photothermal conversion particles of the present invention. (Photothermal conversion layer) may also serve as an image forming layer.
[0065]
When the present invention is applied to a dampening-free photosensitive lithographic printing plate, for example, a photothermal conversion layer containing the photothermal conversion particles of the present invention is provided on a substrate, and an ink repellent layer containing silicone is provided thereon. Provide.
[0066]
The photothermal conversion layer absorbs infrared light and converts it into heat to cause ablation of the photothermal conversion layer and remove the photothermal conversion layer, and at the same time, induces ablation of the ink repellent layer in response to the heat generated thereby.
[0067]
In addition to the photothermal conversion particles, an organic polymer substance can be added to the photothermal conversion layer for the purpose of enhancing the coating properties, the dispersibility of the photothermal conversion particles, the film strength of the photothermal conversion layer, and the ablation effect. .
[0068]
Examples of the organic polymer substance include unsaturated acids such as (meth) acrylic acid and itaconic acid, alkyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, styrene, α- Copolymer with methyl styrene, etc .; Polymer of alkyl methacrylate and alkyl acrylate represented by polymethyl methacrylate; Copolymer with alkyl (meth) acrylate and acrylonitrile, vinyl chloride, vinylidene chloride, styrene, etc .; Copolymer of acrylonitrile and vinyl chloride or vinylidene chloride; modified cellulose having a carboxyl group in the side chain; polyethylene oxide; polyvinyl pyrrolidone; phenol, o-, m-, p-cresol, and / or xyresol and aldehyde, acetone A novolak resin obtained by a condensation reaction with Polyether of chlorohydrin and bisphenol A; soluble nylon; polyvinylidene chloride; chlorinated polyolefin; copolymer of vinyl chloride and vinyl acetate; polymer of vinyl acetate; copolymer of acrylonitrile and styrene; Copolymers with styrene; polyvinyl alkyl ether; polyvinyl alkyl ketone; polystyrene; polyurethane; polyethylene terephthalate isophthalate; acetyl cellulose; acetyl propoxy cellulose; acetyl butoxy cellulose; nitrocellulose; The blending ratio of the organic polymer substance in the photothermal conversion layer is 1 to 60% by mass, preferably 2 to 50% by mass, and more preferably 2 to 40% by mass of the total photosensitive layer solid content.
[0069]
Of these organic polymer substances, when nitrocellulose is contained in the light-to-heat conversion layer, nitrocellulose is decomposed during exposure to generate gas, which is preferable because the efficiency of ablation is increased.
[0070]
The silicone rubber layer used in the present invention can be appropriately selected from known ones as described in JP-A-7-164773, but the silicone rubber layer composition is cured by a condensation reaction, which will be described below. Two types, a condensation crosslinking type and an addition crosslinking type in which the silicone rubber layer composition is cured by an addition reaction, are preferably used.
[0071]
The condensation-crosslinking type silicone rubber layer used in the present invention contains, as essential components, a linear organopolysiloxane having hydroxyl groups at both ends and a reactive silane compound that crosslinks with the organopolysiloxane to form a silicone rubber layer. Examples of the linear organ polysiloxane having hydroxyl groups at both ends used in the present invention include linear organopolysiloxanes represented by the following general formula (1).
[0072]
[Chemical 1]

[0073]
(Wherein two R¹Each independently represents a hydrogen atom, a methyl group, a phenyl group or a vinyl group, and y represents an integer of 1 or more. ) Among the compounds represented by the general formula (1), R¹Is preferably a methyl group. The weight average molecular weight (hereinafter abbreviated as Mw) of the organopolysiloxane is 5,000 to 1,000,000, preferably 10,000 to 1,000,000. If the Mw is extremely low, the film strength of the silicone rubber layer will be reduced and the printing resistance will be low, and if the Mw is extremely high, the removal effect of the silicone rubber layer by ablation will be reduced, resulting in a decrease in sensitivity and image reproducibility. Cheap.
[0074]
In addition, the reactive silane compound used in the present invention reacts with the hydroxyl group of the linear organopolysiloxane having hydroxyl groups at both ends, so that a deacetic acid type, a deoxime type, a dealcohol type, a deamino type, a dehydrated type, etc. It is a reactive silane compound having a molecular weight of 2,000 or less and having at least two functional groups capable of undergoing condensation and crosslinking. Specific examples of the functional group include functional groups represented by the following formulas.
[0075]
[Chemical formula 2]

[0076]
(Wherein R²Represents an alkyl group having 1 to 5 carbon atoms, but two Rs in the same atomic group²Each may be the same or different. ) Of these, the functional group is an acyloxy group (-OCOR²) Having 3 or more functional groups, or the functional group is an alkoxy group (—OR²) Having 3 or more functional groups is preferable because the silicone rubber layer is formed in a short time after the drying treatment after coating. More preferably, the functional group is an acetoxy group and the number of functional groups is 3 or more, or the functional group is an alkoxy group and the number of functional groups is 6 or more.
[0077]
Examples of the reactive silane compound include compounds represented by the following general formulas (2) to (5). In the formula, Q represents one selected from the functional groups that react with the hydroxyl groups of the linear organopolysiloxane having hydroxyl groups at both ends, and Q has at least two in one molecule.
[0078]
[Chemical Formula 3]

[0079]
(Wherein X is an alkyl group having 1 to 5 carbon atoms, phenyl group, vinyl group, H₂N- (CH₂)_h-, CH₂= C (CH_Three) CO-, CH₂= CHCO-,
[0080]
[Formula 4]

[0081]
W represents an oxygen atom, a sulfur atom, -SSSS-, an alkylene group having 1 to 10 carbon atoms, or -N (R^Four)-(CH₂)_q-N (R^Four)-And R²Represents an alkyl group having 1 to 5 carbon atoms as described above, and R^ThreeIs an allyl group or-(CH₂)_q-SiR² _3-pQ_pR^FourRepresents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a phenyl group.², R^Three, R^FourAre present in the same molecule, each of the plurality may be the same or different, h, j and q each represent an integer of 1 to 5, p and r each represent 1 to 3 S represents an integer of 2 to 4, and t and u each represents an integer of 0 to 5. ) Specific examples of the reactive silane compound used in the present invention are given below, but the reactive silane compound is not limited to those exemplified.
[0082]
[Chemical formula 5]

[0083]
[Chemical 6]

[0084]
[Chemical 7]

[0085]
The condensation-crosslinking type silicone rubber layer used in the present invention is an organic carboxylic acid, a titanate ester, in order to increase the reaction efficiency of the condensation-crosslinking reaction between the organopolysiloxane having a hydroxyl group at both ends and a reactive silane compound. Condensation catalysts such as stannic acid esters, aluminum organic ethers, and platinum-based catalysts are mixed as appropriate, and a condensation reaction is performed for curing.
[0086]
The organopolysiloxane having a hydroxyl group at both ends used in the present invention, the reactive silane compound, and the condensation ratio in the silicone rubber layer of the condensation catalyst are as follows. The siloxane is 80 to 98% by mass, preferably 85 to 98% by mass, the reactive silane compound is usually 2 to 20% by mass, preferably 2 to 15% by mass, more preferably 2 to 7% by mass, and the condensation catalyst is 0. 0.05 to 5% by mass, preferably 0.1 to 3% by mass, and more preferably 0.1 to 1% by mass.
[0087]
When the ratio of the reactive silane compound or the condensation catalyst is extremely high, the ink repellency is lowered, and it becomes difficult to remove the silicone rubber layer at the time of ablation, and the sensitivity and the image reproducibility are lowered. On the other hand, if it is extremely low, the film strength of the silicone rubber layer is lowered and the printing durability is lowered.
[0088]
In the condensation-crosslinking type silicone rubber layer used in the present invention, in order to increase the ink repellency of the silicone rubber layer, a polysiloxane other than the polyorganosiloxane having a hydroxyl group at both ends is added to the total solid content of the silicone rubber layer. On the other hand, 2-15 mass%, Preferably 3-12 mass% can be contained. Examples of the polysiloxane include Mw 10,000 to 1,000,000 polydimethylsiloxane having both ends trimethylsilylated.
[0089]
Next, the addition-crosslinking type silicone rubber layer used in the present invention has an organopolysiloxane having at least two aliphatic unsaturated groups in one molecule, and is crosslinked with the organopolysiloxane to form a silicone rubber layer. An organopolysiloxane having at least two Si—H bonds in one molecule is contained as an essential component.
[0090]
The organopolysiloxane having at least two aliphatic unsaturated groups in one molecule used in the present invention may have a chain, cyclic or branched structure, but is preferably a chain. Examples of aliphatic unsaturated groups include vinyl, allyl, butenyl, pentenyl, hexenyl and other alkenyl groups; cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl and other cycloalkenyl groups; ethynyl group And alkynyl groups such as propynyl group, butynyl group, pentynyl group and hexynyl group. Among these, an alkenyl group having an unsaturated bond at the terminal is preferable from the viewpoint of reactivity, and a vinyl group is particularly preferable. Further, the remaining substituents other than the aliphatic unsaturated group are preferably methyl groups in order to obtain good printing ink repellency.
[0091]
The Mw of the organopolysiloxane having at least two aliphatic unsaturated groups in one molecule is usually 500 to 500,000, preferably 1,000 to 300,000. When Mw is extremely low, the strength of the silicone rubber layer is lowered, the silicone rubber layer is easily damaged during printing, the ink repellent property of the printed ink is lowered, the ink is liable to adhere, and it causes printing stains. . On the other hand, if Mw is extremely high, removal of the silicone rubber layer by ablation becomes poor, and sensitivity and image reproducibility are liable to be lowered.
[0092]
The organopolysiloxane having at least two Si-H bonds in one molecule used in the present invention may have a chain, cyclic or branched structure, but is preferably a chain. The Si—H bond may be either at the end or in the middle of the siloxane skeleton, and the proportion of hydrogen atoms to the total number of substituents is usually 1 to 60%, preferably 2 to 50%. Further, the remaining substituents other than hydrogen atoms are preferably methyl groups in order to obtain good printing ink repellency. The Mw of the organopolysiloxane having at least two Si-H bonds in one molecule is usually 300 to 300,000, preferably 500 to 200,000. If Mw is extremely high, sensitivity and image reproducibility are liable to be lowered.
[0093]
Usually, an addition reaction catalyst is used for the addition reaction of the organopolysiloxane having at least two aliphatic unsaturated groups in one molecule and the organopolysiloxane having at least two Si-H bonds in one molecule. . The addition reaction catalyst can be arbitrarily selected from known catalysts, but platinum-based catalysts are preferred, and one or a mixture of two or more selected from platinum group metals and platinum group compounds are used. Examples of the platinum group metal include platinum alone (eg, platinum black), palladium alone (eg, palladium black), and rhodium alone. Examples of platinum group compounds include chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, platinum-ketone complexes, platinum and vinylsiloxane complexes, tetrakis (triphenylphosphine) platinum, tetrakis (triphenylphosphine) palladium, and the like. Is exemplified. Among these, those obtained by dissolving chloroplatinic acid or a platinum-olefin complex in an alcohol solvent, a ketone solvent, an ether solvent, a hydrocarbon solvent, or the like are particularly preferable.
[0094]
The blending ratio of each composition forming the silicone rubber layer is 80 to 98 mass by weight of organopolysiloxane having at least two aliphatic unsaturated groups in one molecule with respect to the total solid content of the silicone rubber layer. %, Preferably 85 to 98% by mass, and organopolysiloxane having at least two Si-H bonds in one molecule is 2 to 20% by mass, preferably 2 to 15% by mass, and the addition reaction catalyst is 0.00001 to 10% by mass, preferably 0.0001 to 5% by mass.
[0095]
If the compounding ratio of the organopolysiloxane having at least two Si-H bonds in one molecule is extremely low, the film strength of the silicone rubber layer is lowered, the printing ink repellent property and printing resistance are lowered, and the compounding ratio is extremely high. And sensitivity and image reproducibility deteriorate. In addition to the above composition, the addition-crosslinking type silicone rubber layer used in the present invention further has a hydrolyzable group represented by the following general formula (6) for the purpose of increasing the film strength of the silicone rubber layer. An amino-based organosilicon compound having can be added.
[0096]
[Chemical 8]

[0097]
(In the formula, Z represents a hydrolyzable group, R^FiveRepresents a divalent hydrocarbon group, R⁶Represents a monovalent optionally substituted hydrocarbon group, and two R⁷Each independently represents a hydrogen atom, a monovalent optionally substituted hydrocarbon group or -R.^Five-SiR⁶ _3-pZ_pAnd p represents an integer of 1 to 3. )
Examples of the hydrolyzable group represented by Z include an alkoxy group such as a methoxy group, an ethoxy group and a propoxy group; an alkenyloxy group such as a 2-propenyloxy group; an aryloxy group such as a phenoxy group; an acetyloxy group and the like An acyloxy group etc. are mentioned. Among these, a methoxy group, an ethoxy group, and an acetyloxy group are preferable from the viewpoints of stability and curability. R^FiveExamples of the divalent hydrocarbon group of
[0098]
[Chemical 9]

[0099]
Is preferred. R⁶And R⁷Among the substituents represented by formula (1), the monovalent optionally substituted hydrocarbon group includes, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, and a butyl group; a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, Cycloalkyl groups such as cyclohexyl group, cycloheptyl group, cyclooctyl group; alkenyl groups such as vinyl group, allyl group, butenyl group, pentenyl group, hexenyl group; cyclopentenyl group, cyclohexenyl group, cycloheptenyl group, cyclooctenyl group, etc. A substituted alkyl group such as a glycidoxypropyl group, an acryloxypropyl group, a methacryloxypropyl group, and an aminoethyl group. R in terms of curability⁶And R⁷Is preferably a vinyl group, an allyl group, a glycidyl group, a methacryl group, or a γ-glycidoxypropyl group.
[0100]
Specific examples of the amino silicon compound include 3- [N-allyl-N- (2-aminoethyl)] aminopropyltrimethoxysilane, 3- (N-allyl-N-glycidyl) aminopropyltrimethoxysilane. 3- (N-allyl-N-methacryl) aminopropyltrimethoxysilane, N-glycidyl-N, N-bis [3- (methyldimethoxysilyl) propyl] amine, N-glycidyl-N, N-bis [3 -(Trimethoxysilyl) propyl] amine, aminopropyltrimethoxysilane, aminopropyltriacetyloxysilane, 3- [N-allyl-N- (2-aminoethyl)] aminopropyltriacetyloxysilane, 3- (N -Allyl-N-glycidyl) aminopropyltriacetyloxysilane, 3- (N-allyl-N- Methacrylic) aminopropyltrimethoxysilane acetyloxy silane, and the like. You may use these in mixture of 2 or more types.
[0101]
The amino-based organosilicon compound is 0 to 10% by mass, preferably 0 to 5% by mass, based on the total solid content of the silicone rubber layer. In addition, a curing retarder can be added to the addition-crosslinking type silicone rubber layer used in the present invention in order to prevent rapid curing of the silicone layer composition when the silicone rubber layer is applied. The curing retarder can be arbitrarily selected from generally known acetylenic alcohols, maleic acid esters, silylated products of acetylenic alcohols, silylated products of maleic acid, triallyl isocyanurate, vinyl siloxane and the like.
[0102]
Although the addition amount of this hardening retarder changes with desired hardening speed | rates, it is 0.0001-1.0 mass part normally with respect to the total solid of a silicone rubber layer. In order to improve the strength, the above-mentioned condensation crosslinking type and addition crosslinking type silicone rubber layers used in the present invention may contain inorganic fillers such as silica, titanium oxide, and aluminum oxide. Is preferably used. As such a filler, those having an average particle diameter of 500 μm or less are preferable from the viewpoint of dispersibility or dispersion stability.
[0103]
These silicone rubber layers are excellent in printing ink repellency and printing resistance, and are easily removed by ablation, and have a function of giving high sensitivity and high image reproducibility. The silicone rubber layer preferably has a scratch strength of 10 to 100 g. However, the scratching strength is the weight necessary to cause scratching when a sapphire needle having a tip diameter of 0.2 mm is moved on the printing plate at a speed of 10 cm / min while applying a load. (G) is represented. When the scratch scratch strength is in the above range, printing aptitude such as printing ink repellent property, printing resistance, sensitivity, and image reproducibility is good. The film thickness of the silicone rubber layer used in the present invention is 0.1 to 10 μm, preferably 0.2 to 5 μm, more preferably 0.3 to 2 μm.
[0104]
The photothermal conversion layer composition and the silicone rubber layer composition described above are dissolved in an appropriate solvent to form a solution, and this is supported on the substrate by various coating devices such as a wire bar, a spinner, and a roll coater. After coating, it can be dried to form a photothermal conversion layer and a silicone rubber layer, respectively. Examples of the coating solvent for the photothermal conversion layer include ketones such as methyl ethyl ketone and cyclohexanone, esters such as butyl acetate, amyl acetate and ethyl propionate, hydrocarbons such as toluene, xylene, monochlorobenzene, carbon tetrachloride, trichloroethylene and trichloroethane. And halogenated hydrocarbons, ethers such as methyl cellosolve, ethyl cellosolve, and tetrahydrofuran, as well as conventional ones such as propylene glycol monomethyl ether acetate, bentoxone, and dimethylformamide can be used as the coating solvent for the silicone rubber layer. n-hexane, cyclohexane, petroleum ether, aliphatic hydrocarbon solvent Exxon Chemical Co., Ltd .: Isopar E, H, G and mixed solvents of these solvents and the above-mentioned photothermal conversion layer coating solvent, etc. are used. Rukoto can.
[0105]
In addition, when the silicone rubber layer used in the present invention is applied, an adhesive layer is provided between the photothermal conversion layer and the silicone rubber layer for the purpose of improving the adhesion between the photothermal conversion layer and the silicone rubber layer. Can do. In general, the adhesive layer can be appropriately selected from the organic polymer materials described in the description of the photothermal conversion layer and the silicone rubber described in the description of the silicone rubber layer. Is a combination of a urethane-type organic polymer substance or a condensed reactive silane compound such as polyfunctional alkoxysilane or polyfunctional acetoxysilane and polydimethylsiloxane having a reactive group such as a hydroxyl group at both ends or main chain. Composition is used. More specifically, Toyobo Co., Ltd. Byron 300, Byron UR8200, Toray Silicone Co., Ltd. Primer A, Primer B, Primer C, Primer D, Primer D2, Primer E, Takeda Pharmaceutical Taketake A367H and Takenate A- 7, a combination of Takenate A-9690 and Takenate A-5, a combination of Takenate A-968 and Takenate A-8, and the like. These adhesive layers are usually used after being applied and dried so as to have a dry film thickness of 0.05 to 10 μm, preferably 0.1 to 2 μm.
[0106]
If necessary, for the purpose of protecting the silicone rubber layer, various releasable plastic sheets such as polypropylene sheet, polyethylene sheet, release-treated polyethylene terephthalate, release-treated paper, metal sheets such as aluminum, iron, copper, etc. Etc. can be laminated on the silicone rubber layer. The photosensitive printing plate provided with the photothermal conversion layer and the silicone rubber layer on the substrate is usually scanned and exposed by a beam spot obtained by condensing a semiconductor laser beam that oscillates near-infrared light of 680 to 1200 nm in a diameter of 5 to 30 μm. After the exposed portion is ablated, it is used as a printing plate without post-treatment, but for the purpose of removing fine particles of the photothermal conversion layer or silicone rubber layer generated by ablation adhering to the exposed printing plate. The silicone rubber layer surface may be subjected to post-treatment that gives physical stimulation such as brush, pad, ultrasonic wave, spray, etc. while supplying an aqueous solution or organic solvent as necessary.
[0107]
Further, as another method of removing the fine particles generated by the ablation, a cover sheet having a surface having a higher adhesion to the fine particles than the silicone rubber layer is exposed on the silicone rubber layer of the exposed photosensitive printing plate. After laminating so that the surface of the silicone rubber and the surface of the adhesive cover sheet are combined, a method of peeling, or before the exposure, laminating the cover sheet and the cover sheet that transmits laser light in the same manner as described above, and after the exposure Examples include peeling and removing fine particles on the silicone rubber layer. Examples of the cover sheet include those in which an adhesive layer such as silicone rubber, ionomer, vinyl acetate or the like is provided on a base plate such as polyethylene terephthalate, polypropylene, polycarbonate, paper, or the like.
[0108]
The photothermal conversion layer when the silicone rubber layer is provided is preferably not an ink repellent layer.
[0109]
When the present invention is applied to a printing plate material for preparing a printing plate using a fountain solution, the layer containing the photothermal conversion particles of the present invention itself is made hydrophilic, more preferably a hydrophilic and porous coating film. Alternatively, a hydrophilic layer is provided on the layer containing the photothermal conversion particles. These hydrophilic layer surfaces serve as non-image portions of the printing plate. Furthermore, an image can be formed by heat mode laser exposure by providing a layer having an image forming function by heat, or imparting a hydrophilic layer itself with a function of changing to lipophilicity by heat. The printing plate material will be described in more detail.
[0110]
The printing plate material has a support (base material) and one or more constituent layers. Preferably, the constituent layer is preferably porous, and more preferably, the constituent layer contains porous particles. The printing plate material is preferably a lithographic printing plate material. Various printing plates can be used for CTP, but are not limited thereto.
[0111]
Examples of the printing plate material include a printing plate material in which the photothermal conversion layer also serves as an image recording layer and a printing plate material having an image recording layer in addition to the photothermal conversion layer. . When the photothermal conversion layer also serves as the image recording layer, the photothermal conversion layer is preferably a hydrophilic layer, and the exposed portion of the photothermal conversion layer preferably changes to ink acceptability. When the photothermal conversion layer and the image recording layer are different, the entire image recording layer may be an ink receiving layer, or the image recording layer is a hydrophilic layer and an exposed portion of the image recording layer May be changed to ink acceptability. Further, a hydrophilic layer may be further provided on the image recording layer. This image recording layer preferably contains a material that melts into heat.
[0112]
Examples of materials that can be added to the hydrophilic layer include the following a to e.
a. Porous silica or porous aluminosilicate particles
The porous silica particles are generally produced by a wet method or a dry method. In the wet method, it can be obtained by drying and pulverizing a gel obtained by neutralizing an aqueous silicate solution, or by pulverizing a precipitate deposited after neutralization. In the dry method, silicon tetrachloride is burned together with hydrogen and oxygen to obtain silica. These particles can be controlled in porosity and particle size by adjusting the production conditions. As the porous silica particles, those obtained from a wet gel are particularly preferable.
[0113]
The porous aluminosilicate particles are produced, for example, by the method described in JP-A-10-71764. That is, it is an amorphous composite particle synthesized by hydrolysis using aluminum alkoxide and silicon alkoxide as main components. The ratio of alumina to silica in the particles can be synthesized in the range of 1: 4 to 4: 1. Moreover, what was manufactured as composite particle | grains of 3 or more components by adding the alkoxide of another metal at the time of manufacture can be used for this invention. These composite particles can also control the porosity and particle size by adjusting the production conditions.
[0114]
The porosity of the particles is preferably 1.0 ml / g or more, more preferably 1.2 ml / g or more, and more preferably 1.8 ml / g or more in the state before dispersion. More preferably, it is 5 ml / g or less. The pore volume is closely related to the water retention of the coating film. The larger the pore volume, the better the water retention and the less smudged during printing, and the greater the water volume latitude, but greater than 2.5 ml / g. Then, since the particles themselves become very brittle, the durability of the coating film decreases. When the pore volume is less than 1.0 ml / g, it is difficult to stain during printing and the water amount latitude is insufficient.
[0115]
The particle size is preferably substantially 1 μm or less, more preferably 0.5 μm or less, in a state where it is contained in the hydrophilic layer (including the case where the dispersion crushing step is performed). When coarse particles are present, porous and steep protrusions are formed on the surface of the hydrophilic layer, so that ink tends to remain around the protrusions and the non-image area stains deteriorate.
[0116]
b. Zeolite particles
Zeolite is a crystalline aluminosilicate and is a porous body having regular three-dimensional network voids having a pore diameter of 0.3 to 1 nm. The general formula combining natural and synthetic zeolite is expressed as follows:
[0117]
(MI, MII_1/2)_m(Al_mSi_nO_{2 (m + n)}XH₂O
Here, MI and MII are exchangeable cations, and MI is Li⁺, Na⁺, K⁺, Tl⁺, Me_FourN⁺(TMA), Et_FourN⁺(TEA), Pr_FourN⁺(TPA), C₇H₁₅N₂ ⁺, C₈H₁₆N⁺MII is Ca²⁺, Mg²⁺, Ba²⁺, Sr²⁺, C₈H₁₈N₂ ²⁺Etc. Further, n ≧ m, and the value of m / n, that is, the Al / Si ratio is 1 or less. The higher the Al / Si ratio, the greater the amount of exchangeable cations and the higher the polarity and therefore the higher the hydrophilicity. A preferable Al / Si ratio is 0.4 to 1.0, and more preferably 0.8 to 1.0.
[0118]
The zeolite particles used in the present invention are preferably synthetic zeolites having a stable Al / Si ratio and a relatively sharp particle size distribution, such as zeolite A: Na.₁₂(Al₁₂Si₁₂O₄₈27H₂O: Al / Si ratio 1.0, zeolite X: Na₈₆(Al₈₆Si₁₀₆O₃₈₄) ・ 264H₂O: Al / Si ratio 0.811, zeolite Y: Na₅₆(Al₅₆Si₁₃₆O₃₈₄) ・ 250H₂O; Al / Si ratio 0.412 and the like.
[0119]
By containing highly hydrophilic porous particles having an Al / Si ratio of 0.4 to 1.0, the hydrophilicity of the hydrophilic layer itself is greatly improved, it is difficult to get dirty during printing, and the water latitude is widened. Also, fingerprint marks are greatly improved. When the Al / Si ratio is less than 0.4, the hydrophilicity is insufficient, and the effect of improving the performance becomes small. The particle size is preferably substantially 1 μm or less, more preferably 0.5 μm or less, in a state where it is contained in the hydrophilic layer (including the case where the dispersion crushing step is performed). When coarse particles are present, porous and steep protrusions are formed on the surface of the hydrophilic layer, so that ink tends to remain around the protrusions and the non-image area stains deteriorate. The porous particles are preferably 30 to 95% by mass, and preferably 50 to 90% by mass of the entire hydrophilic layer (in the case where the hydrophilic layer contains photothermal conversion particles, excluding the photothermal conversion particles). Is more preferable.
[0120]
c. Metal oxide fine particles having an average particle size of 100 nm or less
Examples of the metal oxide fine particles having an average particle size of 100 nm or less include colloidal silica, alumina sol, titania sol, and other metal oxide sols. The form of the metal oxide fine particles may be spherical, needle-like, feather-like, or any other form. The average particle diameter is preferably 3 to 100 nm, and several kinds of metal oxide fine particles having different average particle diameters can be used in combination. Further, the surface of the particles may be subjected to a surface treatment. The metal oxide fine particles can be used as a binder by utilizing the film forming property. The decrease in hydrophilicity is less than when an organic binder is used, and it is suitable for use in a hydrophilic layer. Among the above, colloidal silica is particularly preferable because of its high film forming property even under relatively low temperature drying conditions. In the case of colloidal silica, the smaller the particle size, the stronger the binding force. When the particle diameter is larger than 100 nm, the binding force is greatly reduced, and the strength is insufficient when used as a binder.
[0121]
When these metal oxide fine particles are used together with porous silica particles, the fine particles themselves are preferably used in a positively charged state, for example, alumina sol or acidic colloidal silica is preferably used. In addition, when these metal oxide fine particles are used together with porous aluminosilicate particles and / or zeolite particles, it is preferable to use the fine particles themselves in a state of negative charge, for example, using alkali colloidal silica. Is preferred. When used together with porous silica particles and porous aluminosilicate particles and / or zeolite particles, for example, it is preferable to use colloidal silica having a surface treated with Al to provide stability in a wide pH range.
[0122]
d. Inorganic particles with a new Mohs hardness of 5 or more
Non-porous metal oxide particles (silica, alumina, titania, zirconia, iron oxide, chromium oxide, etc.), metal carbide particles (silicon carbide, etc.), boron nitride particles, diamond particles and the like can be mentioned. It is preferable that the particles do not have an acute angle. For example, particles having a nearly spherical shape such as fused silica particles and shirasu balloon particles are preferable.
[0123]
As an indicator of not being porous, the specific surface area is 50 m in BET value.²/ G or less, preferably 10 m²/ G or less is more preferable. The average particle diameter is preferably 1 to 2 times the thickness of the hydrophilic layer, more preferably 1.1 to 1.5 times. Further, the particle size distribution is preferably sharp, preferably 60% or more of the whole is contained in the range of 0.8 to 1.2 times the average particle size, and more than 2 times the average particle size. It is preferable that it is 5% or less.
[0124]
The thickness of the hydrophilic layer is preferably 0.2 to 10 μm, and more preferably 0.5 to 5 μm. Therefore, the average particle size is preferably 0.2 to 20 μm, and more preferably 0.5 to 10 μm.
[0125]
The content of the inorganic particles having a new Mohs hardness of 5 or more is 1 to 50% by mass of the entire hydrophilic layer (in the case where the hydrophilic layer includes photothermal conversion particles, excluding the photothermal conversion particles). Preferably, it is 3-30 mass%.
[0126]
e. Layered mineral particles
Layered mineral particles include kaolinite, halloysite, chrysotile, talc, smectite (montmorillonite, beidellite, hectorite, sabonite, etc.), clay minerals such as vermiculite, mica (mica), chlorite, hydrotalcite, layered polysilicate (Kanemite, macatite, ialite, magadiaite, Kenyaite, etc.).
[0127]
Among them, it is considered that the higher the charge density of the unit layer (unit layer), the higher the polarity and the higher the hydrophilicity. The charge density is preferably 0.25 or more, more preferably 0.6 or more. Examples of layered minerals having such a charge density include smectite (charge density 0.25 to 0.6; negative charge), vermiculite (charge density 0.6 to 0.9; negative charge), mica (~ 1; negative charge). Charge), hydrotalcite (˜2; positive charge), magadiite (˜1; negative charge) and the like. In particular, synthetic fluoromica is preferable because it can be obtained with stable quality such as particle size. Among the synthetic fluorine mica, those that are swellable are preferable, and those that are free swell are more preferable.
[0128]
In addition, intercalation compounds (such as pillared crystals) of the layered mineral, those subjected to ion exchange treatment, and those subjected to surface treatment (such as a silane coupling agent) can also be used.
[0129]
The size of the plate-like layered mineral particles is 20 μm or less in average particle size (maximum particle length) in the state of being contained in the hydrophilic layer (including the case where the swelling step and the dispersion peeling step are performed). The average aspect ratio (maximum particle length / particle thickness) is preferably a thin layer of 20 or more, more preferably the average particle size is 10 μm or less, and the average aspect ratio is 50 or more. When the particle size is in the above range, the coating film is provided with the continuity and flexibility in the planar direction, which are the characteristics of the thin layered particles, and it is possible to obtain a tough coating film that is hard to crack. When the particle diameter is out of the above range, the dirt on the non-image area and the blanket dirt may deteriorate with an unnecessary increase in surface roughness. On the other hand, when the aspect ratio is not more than the above range, the flexibility becomes insufficient, and the crack suppressing effect of the coating film is reduced. The content of the layered mineral particles is preferably 1 to 50% by mass of the entire hydrophilic layer (in the case where the hydrophilic layer includes photothermal conversion particles, excluding the photothermal conversion particles), and preferably 3 to 30%. More preferably, it is mass%.
[0130]
The porous particles and the layered mineral particles are used after being dispersed, crushed or dispersed. Particle dispersion and delamination methods can be broadly classified into dry and wet methods. The dry dispersion crushing does not require a drying process, and thus the process is relatively simple. However, wet dispersion is usually more advantageous for dispersion crushing up to submicron order and delamination up to a layer thickness of 100 nm or less.
[0131]
Dry dispersion crushing devices include high-speed rotational impact shearing mills (eg, an annular type inomizer), airflow type crushers (jet mills), roll type mills, dry media agitation mills (eg, ball mills), and compression shearing type crushers. (For example, ang mill) can be used. As a wet dispersion crushing apparatus, a wet medium stirring mill (for example, a ball mill or an aquamizer), a high-speed rotating shear friction mill (for example, a colloid mill), or the like can be used.
[0132]
The particle size of the porous particles after dispersion and crushing is preferably substantially 1 μm or less, and more preferably 0.5 μm or less. If coarse particles remain, they may be removed by classification or filtration.
[0133]
In addition, the layered mineral particles after dispersion and crushing may be a thin layer having an average particle size (maximum particle length) of 20 μm or less and an average aspect ratio (maximum particle length / particle thickness) of 20 or more. More preferably, the average particle size is 10 μm or less, and the average aspect ratio is 50 or more. Moreover, you may perform the swelling process mentioned later before dispersion | distribution crushing of a layered mineral particle.
[0134]
In particular, when wet dispersion is performed, it is preferable to prepare the coating solution without drying both the porous particles and the layered mineral particles. This is because when the particles subjected to dispersion crushing or dispersion peeling are dried, reaggregation may occur. You may perform concentrating or diluting in order to adjust solid content concentration of a coating liquid.
[0135]
Furthermore, in the dispersion crushing or dispersion layer peeling step, a surface treatment can be performed on the particles by adding a surface treatment agent. In the dispersion crushing or dispersion layer peeling step, other components added to the coating solution may be added and dispersed simultaneously, or after the dispersion crushing or dispersion layer peeling step, other components added to the coating solution. The above components may be added and dispersed again. In the dispersion crushing or dispersion layer peeling process, it is considered that a mechanochemical reaction occurs at the same time, and when dispersed simultaneously with other components added to the coating solution, an effect of improving the strength when it becomes a coating film is obtained. There is a case.
[0136]
Swellable synthetic fluorinated mica, which is free swell, swells sufficiently even when mixed with water and stirred, and is divided into thin layers having an average thickness of 10 nm or less to form a stable dispersion. Mg-vermiculite exhibits swellability by performing, for example, the following ion exchange treatment.
Mg-vermiculite + lithium citrate aq. → Li-vermiculite + magnesium citrate aq.
Furthermore, the Li-vermiculite limitedly swollen by the osmotic pressure can be mechanically dispersed and delaminated to be divided into thin layers having an average thickness of 10 nm or less.
[0137]
In addition to the above components, the hydrophilic layer can contain an organic binder or additive. As the organic binder, those having hydrophilicity are preferable. For example, proteins such as casein, soybean protein, synthetic protein, chitins, starches, gelatins, alginate, polyvinyl alcohol, silyl-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, cellulose derivatives such as methylcellulose, carboxymethylcellulose and hydroxyethylcellulose , Polyethylene oxide, polypropylene oxide, polyethylene glycol, polyvinyl ether, styrene-butadiene copolymer, conjugated diene polymer latex of methyl methacrylate-butadiene copolymer, acrylic polymer latex, vinyl polymer latex, polyacrylamide, Polyvinyl pyrrolidone etc. are mentioned.
[0138]
Further, the hydrophilic layer may contain a cationic resin. Examples of the cationic resin include polyalkylene polyamines such as polyethyleneamine and polypropylene polyamine or derivatives thereof, acrylic resins having a tertiary amino group or a quaternary ammonium group, and diacrylamine. The cationic resin may be added in the form of fine particles. Examples thereof include a cationic microgel described in JP-A-6-161101.
[0139]
Furthermore, you may add a crosslinking agent in a hydrophilic layer. Examples of the crosslinking agent include melamine resins, isocyanate compounds, isoxazoles, aldehydes, N-methylol compounds, dioxane derivatives, active vinyl compounds, and active halogen compounds.
[0140]
A silicate aqueous solution can also be used as a binder to be added to the hydrophilic layer. Alkali metal silicates such as sodium silicate, potassium silicate and lithium silicate are preferred, and their SiO₂/ M₂The O ratio is preferably selected so that the pH of the entire coating solution when the silicate is added does not exceed 13 in terms of preventing dissolution of inorganic particles.
[0141]
As the binder to be added to the hydrophilic layer, an inorganic polymer or an organic-inorganic hybrid polymer by a so-called sol-gel method can be used. The formation of an inorganic polymer or an organic-inorganic hybrid polymer by the sol-gel method is described in, for example, “Application of the sol-gel method” (written by Sakuo Sakuo / Agne Jofusha) or cited in this book. Known methods described in the published literature can be used.
[0142]
The organic component as described above contained in the hydrophilic layer is greatly reduced in hydrophilicity when it is crosslinked to improve durability, water resistance, etc., even if it is a hydrophilic resin. Causes dirt. In addition, the organic component may block the opening of the porous particles, or may penetrate into the pores, thereby impairing the porosity of the hydrophilic layer and reducing water retention. For the above reasons, it is preferable that the amount of the organic component added is small. Specifically, preferably, the amount of the organic component relative to the entire hydrophilic layer (in the case where the hydrophilic layer includes photothermal conversion particles, excluding the photothermal conversion particles) is 0 to 50% by mass ratio, More preferably, it is 1-30%, More preferably, it is 2-20%.
[0143]
As the base material of the printing plate material of the present invention, a known material used as a substrate for a printing plate can be used. For example, a metal plate, a plastic film, paper treated with a polyolefin, a composite base material obtained by appropriately bonding the above materials, and the like can be given. The thickness of the base material is not particularly limited as long as it can be attached to a printing press, but a thickness of 50 to 500 μm is generally easy to handle.
[0144]
Examples of the metal plate include iron, stainless steel, and aluminum. Aluminum is particularly preferable from the relationship between specific gravity and rigidity. The aluminum plate is usually used after degreasing with an alkali, an acid, a solvent or the like in order to remove oil used during rolling and winding existing on the surface. As the degreasing treatment, degreasing with an alkaline aqueous solution is particularly preferable. Moreover, in order to improve adhesiveness with a coating layer, it is preferable to perform an easily bonding process and undercoat layer application | coating to an application surface. For example, a method of dipping in a liquid containing a coupling agent such as a silicate or a silane coupling agent, or applying a liquid and then sufficiently drying may be mentioned. Anodizing treatment is also considered as a kind of easy adhesion treatment and can be used. Moreover, it can also be used combining an anodizing process and the said immersion or application | coating process. Moreover, the aluminum plate roughened by the well-known method can also be used.
[0145]
Examples of the plastic film include polyethylene terephthalate, polyethylene naphthalate, polyimide, polyamide, polycarbonate, polysulfone, polyphenylene oxide, and cellulose esters. In particular, polyethylene terephthalate and polyethylene naphthalate are preferable. These plastic films are preferably subjected to easy adhesion treatment or undercoat layer coating on the coated surface in order to improve adhesion with the coated layer. Examples of the easy adhesion treatment include corona discharge treatment, flame treatment, and ultraviolet irradiation treatment. Examples of the undercoat layer include a layer containing gelatin or latex.
[0146]
In addition, as the composite base material, the above materials are appropriately bonded together, but may be bonded before forming the hydrophilic layer, or may be bonded after forming the hydrophilic layer. You may paste together just before attaching.
[0147]
The image forming method when the present invention is applied to a dampening-free printing plate material will be described by way of an example of a printing plate material constructed in the order of an ink repellent silicone-containing layer, a photothermal conversion layer, and a substrate. It is not limited.
[0148]
Due to heat generated by exposure, all or part of the light-to-heat conversion layer is ablated, or the bond at the interface between the silicone-containing layer and the light-to-heat conversion layer is broken. Since the silicone layer in the exposed area is peeled off by the impact of ablation (partially cracks may be partially scattered), it can be removed with a relatively weak physical force. By making the photothermal conversion layer and / or the substrate surface ink-receptive, the exposed portion becomes an image.
[0149]
As a method for removing the silicone-containing layer in the exposed area, wipe off with a cloth soaked in an appropriate treatment liquid, or remove by rubbing with a rotating brush in an appropriate treatment liquid. In this stage, it can be removed by contact with various rollers and / or separation force.
[0150]
When a printing plate material having a hydrophilic layer containing the photothermal conversion particles of the present invention is used for producing a printing plate using a fountain solution, an image can be formed by the following method, but is not limited thereto. It is not a thing.
[0151]
On the hydrophilic layer containing the photothermal conversion particles of the present invention, an image receiving layer is image-attached with an ink receiving material by a known ink jet method to form an image layer. The ink receiving material has water resistance. The ink receiving element may be a hot-melt material or a thermosetting material or a photo-curable material that is cured by heat or light after image formation.
[0152]
Examples of thermosetting materials include halogenated bisphenol, resorcin, bisphenol F, tetrahydroxyphenyl ethane, novolac, polyhydroxy compound, polyglycol, glycerin triether, polyolefin, epoxidized soybean oil, vinylcyclohexene dioxide, epoxidation A combination of soybean oil with an organic acid or anhydride (eg, phthalic acid, maleic acid, sebacic acid or anhydride), or an organic peroxide (eg, benzoyl peroxide or phthaloid peroxide), diallyl orthophthalate, Diallyl isophthalate or diallyl chlorate, or a combination thereof with an organic oxide (eg, benzoyl peroxide or phthaloid peroxide), N-methyl-N'-methyloluron ethyl ether, N-methyl-N'- D Rolluron ethyl ether, N-ethyl-N'-methyloluron methyl ether, tetramethylolurea, N-methyl-N, N ', N'-trimethylolurea, N-ethyl-N, N', N'-tri Methylolurea, N, N'-diethyl-N, N'-dimethylolurea, mono and polymethylolmelamine, p-methylolphenol, phenol, o-methylolphenol, 2,4-dimethylolphenol or 2,6-diethyl Mention may be made of a combination of methylolphenol and formaldehyde, an aniline resin, a xylene resin, an unsaturated polyester resin, and a furan resin.
[0153]
Examples of photo-curing substances include unsaturated polyesters (examples of dibasic acids: maleic anhydride, fumaric acid, itaconic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydro anhydride Phthalic acid, isophthalic acid, terephthalic acid, trimellitic anhydride and pyromellitic anhydride; examples of polyhydric alcohols: ethylene glycol, propylene glycol, 2,3-butanediol, 1,3-butanediol, neopentyl glycol, 1 , 4-butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, glycerin trimethylolpropane, polyethylene glycol, polypropylene glycol); and acrylate or methacrylate monomers or oligomers (eg, methoxydi) Tylene glycol methacrylate, methoxytetraethylene glycol methacrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypolyethylene glycol methacrylate, 2-hydroxydodecyl methacrylate, 2-hydroxydodecyl acrylate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, ethylene glycol methacrylate, Polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexane glycol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene Recall dimethacrylate, 2,2-bis (4-methacryloxydiethoxyphenyl) propane, diethylene glycol diacrylate, polyethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,6-hexane glycol diacrylate, neopentyl glycol Diacrylate, polypropylene glycol diacrylate, 2,2'-bis (4-acryloxypropyoxyphenyl) propane, 2,2'-bis (4-acryloxydiethoxyphenyl) propane, trimethylolpropane trimethacrylate, trimethylol Ethanetrimethacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, trimethylolmethane triacrylate, trimethylolpro Pan diacrylate monococonut oil fatty acid ester, tetramethylol methane tetraacrylate, dibromoneopentyl glycol dimethacrylate, and 2,3-dibromopropyl acrylate). The photocurable material is generally used with a photopolymerization initiator. Examples of the photopolymerization initiator include aromatic ketones such as benzophenone, acetophenones, diketones, and acyloxime esters.
[0154]
In addition, the thermal transfer layer of the sheet having the ink-receptive thermal transfer layer is adhered to the hydrophilic layer surface by a known thermal transfer method, and is heated in an image-like manner by a thermal head or laser light from the sheet side. After the heat-sensitive transfer layer is transferred from the sheet to the hydrophilic layer surface, the image layer is formed by removing the sheet.
[0155]
A known photocurable or photosoluble photosensitive layer is coated on the hydrophilic layer, and after exposure, the soluble part is removed by development to form an image layer.
[0156]
A known heat (infrared) curable or heat (infrared) soluble photosensitive layer is coated on the hydrophilic layer, and after laser exposure, the soluble portion is removed by development to form an image layer.
[0157]
Heat-melting fine particles (eg, polyethylene wax emulsion) having a melting point of around 100 ° C. are coated on the hydrophilic layer using a suitable water-soluble binder, colloidal silica or the like as a binder, and the heat-melting fine particles are melted by laser exposure to be hydrophilic. An image portion is formed by penetrating into the adhesive layer, and the unexposed portion is removed by washing with water or dissolved by dampening water on a printing press.
[0158]
In the image forming material of the present invention, a material exhibiting visible exposure can be added to any layer on the substrate. For imparting exposure visibility, for example, a known technique used for thermal paper can be applied.
[0159]
The image forming material of the present invention is preferably exposed by a near infrared laser. As the exposure apparatus, a general exposure machine for thermal CTP can be used. Exposure energy is 100-500mJ / cm²Is preferred.
[0160]
  Above is the printing plate materialIsThe present inventionThe theoryRevealed. BookinventionPhotothermal conversion particles according toIs applied to all image forming materials that form images by irradiating light such as laser light and converting the light energy into heat energy by a photothermal conversion material.May. Examples of image forming materials other than printing plate materials include the following.
[0161]
A laser thermal transfer ink sheet having a photothermal conversion layer and an ink layer, a laser thermal transfer image receiving sheet having a thermoplastic resin layer and an image receiving layer, and an ink layer of the ink sheet and an image receiving layer of the image receiving sheet being stacked. An example of an image forming material is a laser thermal transfer recording material that forms an image by irradiating a laser beam imagewise and thermally transferring an ink layer to the image receiving layer and then peeling the ink sheet from the image receiving sheet. . In this case, the photothermal conversion particles of the present invention are contained in the photothermal conversion layer of the ink sheet.
[0162]
As another image forming material, an image forming layer having a colorant (pigment or color particles) is provided on a support, and the image forming layer is irradiated with a laser by imagewise irradiation. An ablation image forming material in which the portion is ablated to form an image is exemplified. In this case, the photothermal conversion particles of the present invention may be contained in the image forming layer, or a photothermal conversion layer may be provided separately from the image forming layer, and the photothermal conversion particles of the present invention may be contained in the photothermal conversion layer. .
[0163]
【Example】
EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples.
[0164]
(Manufacture of photothermal conversion particles)
The surfaces of the core particles shown in Tables 1 and 2 were coated with a photothermal conversion material and other materials by a dry method using a sand grinder and glass beads (Hibee 20). The rotational speed of the disk was 800 rpm. Tables 1 and 2 show the composition of the coating particle suspension (core particle, coating material and dispersion medium) and treatment time. After completion of the treatment, the photothermal conversion particles were sampled, and the surface coverage of the core particles was evaluated by SEM observation. The results are also shown in Tables 1 and 2.
[0165]
The coated photothermal conversion particles were further added to a sand grinder with propylene glycol monomethyl ether acetate or pure water, stirred, separated from glass beads, and recovered as a 10% by mass suspension.
[0166]
[Table 1]

[0167]
[Table 2]

[0168]
Example 1 and Comparative Example 1 (Dampening-free printing plate)
Examples 1-1 to 1-6
A photothermal conversion layer coating solution containing photothermal conversion particles having the composition shown in Tables 3 to 4 was prepared, and applied to a surface of a polyethylene terephthalate film having a thickness of 0.18 mm subjected to corona discharge using a wire bar. And dried at 80 ° C. for 5 minutes to provide a photothermal conversion layer. The coating amount is 1.5 g / m after drying²It was.
[0169]
Comparative Example 1-1
A dispersion having the following composition was prepared and mixed for 1 hour with a planetary mixer, and then passed through a three-roll mill 14 times for pre-dispersion treatment. Then, the solid content concentration is adjusted to 30% by mass with the same solvent, the dispersion treatment is performed for 3 hours using 1 mmφ zirconia beads with a sand grinder, and the solid content concentration is further adjusted to 10% by mass with the same solvent. A photothermal conversion layer coating solution was applied and dried on a polyethylene terephthalate film having a thickness of 0.18 mm in the same manner as in Example 1.
[0170]
Dispersion
Titanium Black 13M (Mitsubishi Materials Corporation) 15 parts by mass
Nitrocellulose 35 parts by weight
50 parts by mass of propylene glycol monomethyl ether acetate
Comparative Example 1-2
The photothermal conversion layer was formed on the polyethylene terephthalate film in the same manner as in Comparative Example 1-1 except that the amount of titanium black 13M in the dispersion composition of Comparative Example 1-1 was changed to 20 parts by mass and the amount of nitrocellulose was changed to 30 parts by mass. Was provided.
[0171]
On each of the photothermal conversion layers, a silicone-containing layer coating solution having the following composition was further applied and dried at 100 ° C. for 3 minutes to obtain a dampening-free printing plate material. The coating amount is 1.0 g / m after drying²It was.
[0172]
Silicone-containing layer coating solution
93 g of polydimethylsiloxane (Mw 80000) with hydroxyl groups at both ends
3- [N-allyl-N- (2-aminoethyl)]
Aminopropyltrimethoxysilane 6.3g
Dibutyltin dilaurate 0.7g
Isobar E (Exxon Chemical) 900g
The obtained fountain solution-free printing plate material is wound around a drum of a laser exposure machine with the silicone-containing layer on the outside, and the exposure energy amount is changed with a resolution of 4000 dpi (laser beam diameter 6 μm) with an 830 nm infrared laser. The image was exposed. After exposure, the silicone-containing layer surface of the printing plate was wiped with a soft cloth soaked in water to remove the ablated silicone-containing layer remaining in the exposed area or scattered around it. And the sensitivity and the resolution were evaluated by the following methods. The results are shown in Tables 3-4.
[0173]
Sensitivity evaluation method
DAIYA1F-1 manufactured by Mitsubishi Heavy Industries, Ltd. was used as a printing machine, and printing was performed using coated paper and dampening water-free lithographic printing plate ink (Aquares Echo M Red manufactured by Toyo Ink Co., Ltd.). Sensitivity was defined as the minimum exposure energy amount at which a good printed image without fading was obtained by visual judgment.
[0174]
Resolution evaluation method
The image thin line portion on the paper surface corresponding to the exposure energy amount shown as sensitivity above was observed with a microscope, and the thin line width reproduced without interruption and the sharpness of the thin line edge were evaluated.
[0175]
[Table 3]

[0176]
[Table 4]

[0177]
Example 2 and Comparative Example 2 (printing plate using fountain solution)
Formation of undercoat layer
A polyethylene terephthalate film having a thickness of 0.18 mm was used as a substrate, and an undercoat layer composed of two layers was formed by the following method.
[0178]
First undercoat layer
After the corona discharge treatment is applied to the coated surface of the polyethylene terephthalate film substrate, the coating thickness of the first undercoat layer coating solution having the following composition is 0 after drying with a wire bar in an atmosphere of 20 ° C. and a relative humidity of 55%. The film was applied to a thickness of 4 μm and dried at 140 ° C. for 2 minutes.
[0179]
First undercoat layer coating solution
Acrylic latex particles (n-butyl acrylate /
t-butyl acrylate / styrene / hydroxyethyl methacrylate
= 28/22/25/25) 36.9g
Surfactant (A) 0.36g
Hardener (a) 0.98g
Distilled water was added to make 1000 ml, and a coating solution was obtained.
[0180]
Second undercoat layer
The surface of the film on which the first undercoat layer is formed is subjected to corona discharge treatment, and then the second undercoat layer coating solution having the following composition is dried by an air knife method in an atmosphere of 35 ° C. and a relative humidity of 22%. The film was applied to a thickness of 0.1 μm and dried at 140 ° C. for 2 minutes.
[0181]
Second undercoat layer coating solution
9.6 g of gelatin
Surfactant (A) 0.4g
Hardener (b) 0.1g
Distilled water was added to make 1000 ml, and a coating solution was obtained.
[0182]
[Chemical Formula 10]

[0183]
Formation of layer containing photothermal conversion particles and image forming layer (1)
Examples 2-1 to 2-9, Comparative Examples 2-1 to 2-7
Polyethylene terephthalate having an undercoat layer formed so as to prepare a photothermal conversion layer coating solution containing the aqueous suspension of photothermal conversion particles by the composition and dispersion method shown in Tables 5 to 11 and the coating amount shown in Table 12 The film was coated with a wire bar and dried at 100 ° C. for 5 minutes. In Table 6, the coating of the second layer was coated on the photothermal conversion layer so as to have the coating amount shown in Table 12, and dried at 100 ° C. for 5 minutes.
[0184]
Furthermore, the image forming layer (1) coating solution having the following composition was coated on the photothermal conversion layer using a wire bar and dried at 70 ° C. for 3 minutes. The coating amount is 1.0 g / m²It was.
[0185]

Pure water was added to make the solid content concentration 10.0 mass%.
[0186]
The obtained printing plate material is wound around a drum of a laser exposure machine with the image forming layer facing outside, and resolution (laser beam diameter) of 4000 dpi (how many dots per 24.5 mm is called dpi) with an infrared laser of 830 nm. 6 μm), the exposure energy amount was changed, and imagewise exposure was performed.
[0187]
Evaluation of the presence or absence of ablation during laser exposure
The image portion of the printing plate after exposure was observed with an SEM, and the minimum exposure energy amount at which ablation began to occur was determined.
[0188]
Sensitivity evaluation method
Using DAIYA1F-1 manufactured by Mitsubishi Heavy Industries, Ltd. as a printing machine, coated paper, dampening water (concentration 1.5% H liquid SG-51 manufactured by Tokyo Ink Co., Ltd.), ink (Toyo ink manufactured by Toyo Ink Co., Ltd.) Printing was performed using High Echo M Red. Sensitivity was defined as the minimum exposure energy amount at which a good printed image without fading was obtained by visual judgment. The results are shown in Table 13.
[0189]
Resolution evaluation method
The image thin line portion on the paper surface corresponding to the exposure energy amount shown as sensitivity above was observed with a microscope, and the thin line width reproduced without interruption and the sharpness of the thin line edge were evaluated. The results are shown in Table 13.
[0190]
[Table 5]

[0191]
[Table 6]

[0192]
[Table 7]

[0193]
[Table 8]

[0194]
[Table 9]

[0195]
[Table 10]

[0196]
[Table 11]

[0197]
[Table 12]

[0198]
[Table 13]

[0199]
Formation of layer containing photothermal conversion particles and image forming layer (2)
Examples 3-1 to 3-4, comparative examples 3-1 to 3-4
Polyethylene terephthalate having an undercoat layer formed so as to prepare a photothermal conversion layer coating solution containing the aqueous suspension of photothermal conversion particles by the composition and dispersion method shown in Tables 5 to 11 and having the coating amount shown in Table 14 The film was coated with a wire bar and dried at 100 ° C. for 5 minutes. Furthermore, the following image forming layer (2) coating solution was prepared, coated on the photothermal conversion layer using a wire bar, and dried at 70 ° C. for 3 minutes. Application amount is 0.6g / m²It was.
[0200]

Pure water was added to make the solid content concentration 10.0 mass%.
[0201]
Laser exposure was performed in the same manner as in Example 2, image formation was performed, and ablation, sensitivity, and resolution were evaluated. Further, scratch resistance was evaluated by the following method. The results are shown in Table 15.
[0202]
Scratch resistance evaluation method
Using a wear resistance tester (HEIDON-18), changing the load to 50, 100, 150, 200 g with a 0.1 mmφ stylus and sliding the surface of the non-image area of the printing plate after image formation to print It was evaluated how many grams of sliding flaws, sometimes identified as dirt, were attached.
[0203]
[Table 14]

[0204]
[Table 15]

[0205]
【The invention's effect】
According to the present invention, an image forming material having high sensitivity, high resolution, high wear resistance, and capable of heat mode recording that does not cause dirt due to scratches, a photothermal conversion material (photothermal conversion particles) used therein, and the image forming material A manufacturing method is provided, and the water resistance of the constituent layers of the image forming material can be improved.

Claims (6)

A printing plate material having a layer containing photothermal conversion particles obtained by coating a core material surface with a material containing a photothermal conversion material on a substrate. 2. The printing plate material according to claim 1, wherein the light-to-heat conversion material is a conductive metal oxide . The printing plate material of claim 1 or 2 wherein the core material Ru Ah with organic particles. The printing plate material as claimed in any one average particle size of claims 1-3 Ru 0.1~10μm der photothermal conversion particles. The printing plate material according to any one of the light-to-heat conversion Claim surface coverage by the material containing a light-heat conversion material is Ru der least 20% in area of the particle 1-4. A photothermal conversion particle containing a material containing a core material and a photothermal conversion material on a base material, the surface of the core material containing at least photothermal conversion particles coated with the material containing the photothermal conversion material A method for producing a printing plate material having a layer containing photothermal conversion particles, comprising a step of forming a layer by applying a liquid to be coated, wherein the coating of the core material with the material containing the photothermal conversion material is dry-dispersed Or the manufacturing method of the printing plate material performed by the spray-drying method.