JP2004050733A - Imaging method, printed matter, and recording apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging method which can record a precise image excellent in letter quality for all recording materials and free from color mixing and prevents the occurrence of wrinkles and curling in print, a print, and a recording apparatus. <P>SOLUTION: In the imaging method, an active light-curable ink is discharged on a recording material by a recording head having at least one nozzle which can selectively control the discharge of ink drops. The ink contains a compound having a maleimide skeleton and is cured by active light having the maximum degree of illumination in a wavelength range of 280-320 nm. <P>COPYRIGHT: (C)2004,JPO

Description

【００４８】
第２に、スルホン酸を発生するスルホン化物を挙げることが出来、その具体的な化合物を、以下に例示する。
【００４９】
【化３】

【００５０】
第３に、ハロゲン化水素を光発生するハロゲン化物も用いることが出来、以下にその具体的な化合物を例示する。
【００５１】
【化４】

【００５２】
第４に、鉄アレン錯体を挙げることが出来る。
【００５３】
【化５】

【００５４】
次に、本発明に用いられる光重合性化合物について説明する。
カチオン重合性モノマーとしては、各種公知のカチオン重合性のモノマーが使用出来る。例えば、特開平６−９７１４、特開２００１−３１８９２、同２００１−４００６８、同２００１−５５５０７、同２００１−３１０９３８、同２００１−３１０９３７、同２００１−２２０５２６に例示されているエポキシ化合物、ビニルエーテル化合物、オキセタン化合物などが挙げられる。
【００５５】
芳香族エポキシドとして好ましいものは、少なくとも１個の芳香族核を有する多価フェノール或いはそのアルキレンオキサイド付加体とエピクロルヒドリンとの反応によって製造されるジまたはポリグリシジルエーテルであり、例えばビスフェノールＡ或いはそのアルキレンオキサイド付加体のジまたはポリグリシジルエーテル、水素添加ビスフェノールＡ或いはそのアルキレンオキサイド付加体のジまたはポリグリシジルエーテル、並びにノボラック型エポキシ樹脂等が挙げられる。ここでアルキレンオキサイドとしては、エチレンオキサイド及びプロピレンオキサイド等が挙げられる。
【００５６】
脂環式エポキシドとしては、少なくとも１個のシクロへキセンまたはシクロペンテン環等のシクロアルカン環を有する化合物を、過酸化水素、過酸等の適当な酸化剤でエポキシ化することによって得られる、シクロヘキセンオキサイドまたはシクロペンテンオキサイド含有化合物が好ましい。
【００５７】
脂肪族エポキシドの好ましいものとしては、脂肪族多価アルコール或いはそのアルキレンオキサイド付加体のジまたはポリグリシジルエーテル等があり、その代表例としては、エチレングリコールのジグリシジルエーテル、プロピレングリコールのジグリシジルエーテルまたは１，６−ヘキサンジオールのジグリシジルエーテル等のアルキレングリコールのジグリシジルエーテル、グリセリン或いはそのアルキレンオキサイド付加体のジまたはトリグリシジルエーテル等の多価アルコールのポリグリシジルエーテル、ポリエチレングリコール或いはそのアルキレンオキサイド付加体のジグリシジルエーテル、ポリプロピレングリコール或いはそのアルキレンオキサイド付加体のジグリシジルエーテル等のポリアルキレングリコールのジグリシジルエーテル等が挙げられる。ここでアルキレンオキサイドとしては、エチレンオキサイド及びプロピレンオキサイド等が挙げられる。
【００５８】
これらのエポキシドのうち、速硬化性を考慮すると、芳香族エポキシド及び脂環式エポキシドが好ましく、特に脂環式エポキシドが好ましい。本発明では、上記エポキシドの１種を単独で使用してもよいが、２種以上を適宜組み合わせて使用してもよい。
【００５９】
ビニルエーテル化合物としては、例えば、エチレングリコールジビニルエーテル、ジエチレングリコールジビニルエーテル、トリエチレングリコールジビニルエーテル、プロピレングリコールジビニルエーテル、ジプロピレングリコールジビニルエーテル、ブタンジオールジビニルエーテル、ヘキサンジオールジビニルエーテル、シクロヘキサンジメタノールジビニルエーテル、トリメチロールプロパントリビニルエーテル等のジまたはトリビニルエーテル化合物、エチルビニルエーテル、ｎ−ブチルビニルエーテル、イソブチルビニルエーテル、オクタデシルビニルエーテル、シクロヘキシルビニルエーテル、ヒドロキシブチルビニルエーテル、２−エチルヘキシルビニルエーテル、シクロヘキサンジメタノールモノビニルエーテル、ｎ−プロピルビニルエーテル、イソプロピルビニルエーテル、イソプロペニルエーテル−Ｏ−プロピレンカーボネート、ドデシルビニルエーテル、ジエチレングリコールモノビニルエーテル、オクタデシルビニルエーテル等のモノビニルエーテル化合物等が挙げられる。
【００６０】
これらのビニルエーテル化合物のうち、硬化性、密着性、表面硬度を考慮すると、ジまたはトリビニルエーテル化合物が好ましく、特にジビニルエーテル化合物が好ましい。本発明では、上記ビニルエーテル化合物の１種を単独で使用してもよいが、２種以上を適宜組み合わせて使用してもよい。
【００６１】
本発明においては、インク硬化の際の記録材料の収縮を抑える目的で、光重合性化合物として少なくとも１種のオキセタン化合物を含有することが好ましい。
【００６２】
オキセタン化合物は、オキセタン環を有する化合物のことであり、特開２００１−２２０５２６、同２００１−３１０９３７に紹介されているような公知のあらゆるオキセタン化合物を使用出来る。
【００６３】
オキセタン環を５個以上有する化合物を使用すると、インク組成物の粘度が高くなるため、取扱いが困難になったり、又インク組成物のガラス転移温度が高くなるため、得られる硬化物の粘着性が十分でなくなってしまう。オキセタン環を有する化合物は、オキセタン環を１〜４個有する化合物が好ましい。
【００６４】
以下、オキセタン環を有する化合物の具体例について説明するが、本発明はこれらに限定されない。
【００６５】
１個のオキセタン環を有する化合物の一例としては、下記一般式（１）で示される化合物が挙げられる。
【００６６】
【化６】

【００６７】
一般式（１）において、Ｒ^１は水素原子やメチル基、エチル基、プロピル基、ブチル基等の炭素数１〜６のアルキル基、炭素数１〜６のフルオロアルキル基、アリル基、アリール基、フリル基またはチエニル基である。Ｒ^２は、メチル基、エチル基、プロピル基、ブチル基等の炭素数１〜６個のアルキル基、１−プロペニル基、２−プロペニル基、２−メチル−１−プロペニル基、２−メチル−２−プロペニル基、１−ブテニル基、２−ブテニル基、３−ブテニル基等の炭素数２〜６個のアルケニル基、フェニル基、ベンジル基、フルオロベンジル基、メトキシベンジル基、フェノキシエチル基等の芳香環を有する基、エチルカルボニル基、プロピルカルボニル基、ブチルカルボニル基等の炭素数２〜６個のアルキルカルボニル基、エトキシカルボニル基、プロポキシカルボニル基、ブトキシカルボニル基等の炭素数２〜６個のアルコキシカルボニル基、またはエチルカルバモイル基、プロピルカルバモイル基、ブチルカルバモイル基、ペンチルカルバモイル基等の炭素数２〜６個のＮ−アルキルカルバモイル基等である。本発明で使用するオキセタン化合物としては、１個のオキセタン環を有する化合物を使用することが、得られる組成物が粘着性に優れ、低粘度で作業性に優れるため、特に好ましい。
【００６８】
２個のオキセタン環を有する化合物の一例としては、下記一般式（２）で示される化合物等が挙げられる。
【００６９】
【化７】

【００７０】
一般式（２）において、Ｒ^１は、上記一般式（１）におけるそれと同様の基である。Ｒ^３は、例えば、エチレン基、プロピレン基、ブチレン基等の線状または分枝状アルキレン基、ポリ（エチレンオキシ）基、ポリ（プロピレンオキシ）基等の線状または分枝状ポリ（アルキレンオキシ）基、プロペニレン基、メチルプロペニレン基、ブテニレン基等の線状または分枝状不飽和炭化水素基、またはカルボニル基またはカルボニル基を含むアルキレン基、カルボキシル基を含むアルキレン基、カルバモイル基を含むアルキレン基等である。
【００７１】
また、Ｒ^３としては、下記一般式（３）、（４）及び（５）で示される基から選択される多価基も挙げることが出来る。
【００７２】
【化８】

【００７３】
一般式（３）において、Ｒ^４は、水素原子やメチル基、エチル基、プロピル基、ブチル基等の炭素数１〜４個のアルキル基、メトキシ基、エトキシ基、プロポキシ基、ブトキシ基等の炭素数１〜４個のアルコキシ基、塩素原子、臭素原子等のハロゲン原子、ニトロ基、シアノ基、メルカプト基、低級アルコキシカルボニル基、カルボキシル基、またはカルバモイル基である。
【００７４】
【化９】

【００７５】
一般式（４）において、Ｒ^５は、酸素原子、硫黄原子、メチレン基、−ＮＨ−、−ＳＯ−、−ＳＯ_２−、−Ｃ（ＣＦ_３）_２−、または−Ｃ（ＣＨ_３）_２−を表す。
【００７６】
【化１０】

【００７７】
一般式（５）において、Ｒ^６は、メチル基、エチル基、プロピル基、ブチル基等の炭素数１〜４個のアルキル基、またはアリール基である。ｎは０〜２０００の数を表す。Ｒ^７はメチル基、エチル基、プロピル基、ブチル基の炭素数１〜４個のアルキル基、またはアリール基である。Ｒ^７としては、更に、下記一般式（６）で示される基から選択される基も挙げることが出来る。
【００７８】
【化１１】

【００７９】
一般式（６）において、Ｒ^８は、メチル基、エチル基、プロピル基、ブチル基等の炭素数１〜４個のアルキル基、またはアリール基である。ｍは０〜１００の数を表す。
【００８０】
２個のオキセタン環を有する化合物の具体例としては、下記化合物が挙げられる。
【００８１】
【化１２】

【００８２】
例示化合物１は、前記一般式（２）において、Ｒ^１がエチル基、Ｒ^３がカルボニル基である化合物である。また、例示化合物２は、前記一般式（２）において、Ｒ^１がエチル基、Ｒ^３が前記一般式（５）でＲ^６及びＲ^７がメチル基、ｎが１である化合物である。
【００８３】
２個のオキセタン環を有する化合物において、上記の化合物以外の好ましい例としては、下記一般式（７）で示される化合物がある。一般式（７）において、Ｒ^１は、前記一般式（１）のＲ^１と同義である。
【００８４】
【化１３】

【００８５】
また、３〜４個のオキセタン環を有する化合物の一例としては、下記一般式（８）で示される化合物が挙げられる。
【００８６】
【化１４】

【００８７】
一般式（８）において、Ｒ^１は、前記一般式（１）におけるＲ^１と同義である。Ｒ^９としては、例えば、下記Ａ〜Ｃで示される基等の炭素数１〜１２の分枝状アルキレン基、下記Ｄで示される基等の分枝状ポリ（アルキレンオキシ）基または下記Ｅで示される基等の分枝状ポリシロキシ基等が挙げられる。ｊは、３または４である。
【００８８】
【化１５】

【００８９】
上記Ａにおいて、Ｒ^１０はメチル基、エチル基またはプロピル基等の低級アルキル基である。また、上記Ｄにおいて、ｐは１〜１０の整数である。
【００９０】
３〜４個のオキセタン環を有する化合物の中でも、例えば、４個のオキセタン環を有する化合物としては、例示化合物３が挙げられる。
【００９１】
【化１６】

【００９２】
更に、上記説明した以外の１〜４個のオキセタン環を有する化合物の例としては、下記一般式（９）で示される化合物が挙げられる。
【００９３】
【化１７】

【００９４】
一般式（９）において、Ｒ^８は前記一般式（６）のＲ^８と同義である。Ｒ^１１はメチル基、エチル基、プロピル基またはブチル基等の炭素数１〜４のアルキル基またはトリアルキルシリル基であり、ｒは１〜４である。
【００９５】
本発明で使用するオキセタン化合物の好ましい具体例としては、以下に示す化合物がある。
【００９６】
【化１８】

【００９７】
上述したオキセタン環を有する各化合物の製造方法は、特に限定されず、従来知られた方法に従えばよく、例えば、パティソン（Ｄ．Ｂ．Ｐａｔｔｉｓｏｎ，Ｊ．Ａｍ．Ｃｈｅｍ．Ｓｏｃ．，３４５５，７９（１９５７））が開示している、ジオールからのオキセタン環合成法等がある。また、これら以外にも、分子量１０００〜５０００程度の高分子量を有する１〜４個のオキセタン環を有する化合物も挙げられる。これらの具体的化合物例としては、以下の化合物が挙げられる。
【００９８】
【化１９】

【００９９】
また、本発明に係るインクには、前記マレイミド化合物に加えて、光ラジカル発生剤及びラジカル重合性モノマーを含有してもよい。硬化スピードのアップ、インク膜の記録材料への密着性アップ、などの効果があり、好ましい。
【０１００】
光ラジカル発生剤としては、アリールアルキルケトン、オキシムケトン、アシルホスフィンオキシド、アシルホスホナート、チオ安息香酸Ｓ−フェニル、チタノセン、芳香族ケトン、チオキサントン、ベンジルとキノン誘導体またはケトクマリン類などの従来公知のものが使用出来る。
【０１０１】
中でもアシルホスフィンオキシド、アシルホスホナートは感度が高く、開始剤の光開裂により吸収が減少するため、インクジェット方式のように１色当たり５〜１５μｍの厚みを持つインク画像での内部硬化に特に有効である。
【０１０２】
具体的には、ビス（２，４，６−トリメチルベンゾイル）−フェニルホスフィンオキサイド、ビス（２，６−ジメトキシベンゾイル）−２，４，４−トリメチル−ペンチルホスフィンオキサイドなどが好ましい。
【０１０３】
また、高感度、安全性、臭気を考慮した選択では、１−ヒドロキシ−シクロヘキシル−フェニル−ケトン、２−メチル−１［４−（メチルチオ）フェニル］−２−モリホリノプロパン−１−オン、２−ヒドロキシ−２−メチル−１−フェニル−プロパン−１−オン、２−ベンジル−２−ジメチルアミノ−１−（４−モルホリノフェニル）−ブタノン−１が好適に用いられる。
【０１０４】
酸素重合阻害や感度を考慮した組み合わせでは、２−ベンジル−２−ジメチルアミノ−１−（４−モルホリノフェニル）−ブタノン−１と１−ヒドロキシ−シクロヘキシル−フェニル−ケトンとの組み合わせ、１−ヒドロキシ−シクロヘキシル−フェニル−ケトンとベンゾフェノンとの組み合わせ、２−メチル−１［４−（メチルチオ）フェニル］−２−モリホリノプロパン−１−オンまたは２−メチル−１［４−（メチルチオ）フェニル］−２−モリホリノプロパン−１−オンとジエチルチオキサントンもしくはイソプロピルチオキサントンとの組み合わせ、ベンゾフェノンと三級アミノ基を持つアクリル酸誘導体との組み合わせ、三級アミンの添加などが効果的である。
【０１０５】
ラジカル重合性モノマーとしては、各種（メタ）アクリレートモノマーが使用出来る。例えば、イソアミルアクリレート、ステアリルアクリレート、ラウリルアクリレート、オクチルアクリレート、デシルアクリレート、イソミルスチルアクリレート、イソステアリルアクリレート、２−エチルヘキシル−ジグリコールアクリレート、２−ヒドロキシブチルアクリレート、２−アクリロイルオキシエチルヘキサヒドロフタル酸、ブトキシエチルアクリレート、エトキシジエチレングリコールアクリレート、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、メトキシプロピレングリコールアクリレート、フェノキシエチルアクリレート、テトラヒドロフルフリルアクリレート、イソボルニルアクリレート、２−ヒドロキシエチルアクリレート、２−ヒドロキシプロピルアクリレート、２−ヒドロキシ−３−フェノキシプロピルアクリレート、２−アクリロイルオキシエチルコハク酸、２−アクリロイルオキシエチルフタル酸、２−アクリロイルオキシエチル−２−ヒドロキシエチル−フタル酸、ラクトン変性可撓性アクリレート、ｔ−ブチルシクロヘキシルアクリレート等の単官能モノマー、トリエチレングリコールジアクリレート、テトラ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、トリプロピレン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、１，４−ブタンジオールジアクリレート、１，６−ヘキサンジオールジアクリレート、１，９−ノナンジオ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、ジメチロール−トリシクロデカンジアクリレート、ビスフェノールＡのＥＯ付加物ジアクリレート、ビスフェノールＡのＰＯ付加物ジアクリレート、ヒドロキシピバリン酸ネオペンチルグリコールジアクリレート、ポリテトラメチレングリコールジアクリレート等の二官能モノマー、トリメチロールプロパントリアクリレート、ＥＯ変性トリメチロールプロパントリアクリレート、ペンタエリスリトールトリアクリレート、ペンタエリスリトールテトラアクリレート、ジペンタエリスリトールヘキサアクリレート、ジトリメチロールプロパンテトラアクリレート、グリセリンプロポキシトリアクリレート、カプロラクトン変性トリメチロールプロパントリアクリレート、ペンタエリスリトールエトキシテトラアクリレート、カプロラクタム変性ジペンタエリスリトールヘキサアクリレート等の三官能以上の多官能モノマーが挙げられる。
【０１０６】
尚、活性光線を照射したときの硬化収縮率を抑えるために、モノマー単体の硬化収縮率は１０％以下のものを用いることが好ましい。中でも単官能モノマーは、二官能以上のモノマーに比べて低収縮率であるとともに、インク画像に可撓性を持たせるため、カールの抑制、記録材料への密着性を得る点で用いることが好ましい。
【０１０７】
この他、感作性、皮膚刺激性、眼刺激性、変異原性、毒性など安全性の観点から、上記モノマーの中でも特に、イソアミルアクリレート、ステアリルアクリレート、ラウリルアクリレート、オクチルアクリレート、デシルアクリレート、イソミルスチルアクリレート、イソステアリルアクリレート、エ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、メトキシプロピレングリコールアクリレート、イソボルニルアクリレート、ラクトン変性可撓性アクリレート、テトラ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、ポリプロピレングリコールジアクリレート、ＥＯ変性トリメチロールプロパントリアクリレート、ジペンタエリスリトールヘキサアクリレート、ジトリメチロールプロパンテトラアクリレート、グリセリンプロポキシトリアクリレート、カウプロラクトン変性トリメチロールプロパントリアクリレート、ペンタエリスリトールエトキシテトラアクリレート、カプロラクタム変性ジペンタエリスリトールヘキサアクリレートが好ましい。
【０１０８】
更にこの中でも、ステアリルアクリレート、ラウリルアクリレート、イソステアリルアクリレート、エトキシジエチレングリコールアクリレート、イソボルニルアクリレート、テトラエチレングリコールジアクリレート、ＥＯ変性トリメチロールプロパントリアクリレート、グリセリンプロポキシトリアクリレート、カウプロラクトン変性トリメチロールプロパントリアクリレート、カプロラクタム変性ジペンタエリスリトールヘキサアクリレートが特に好ましい
本発明に係るインク組成物を着色する場合は、色材を添加する。色材としては、重合性化合物の主成分に溶解または分散出来る各種色材を使用することが出来るが、耐候性の観点から顔料が好ましい。
【０１０９】
本発明で好ましく用いることの出来る顔料を、以下に列挙する。
Ｃ．Ｉ　Ｐｉｇｍｅｎｔ　Ｙｅｌｌｏｗ−１、３、１２、１３、１４、１７、８１、８３、８７、９５、１０９、４２、
Ｃ．Ｉ　Ｐｉｇｍｅｎｔ　Ｏｒａｎｇｅ−１６、３６、３８、
Ｃ．Ｉ　Ｐｉｇｍｅｎｔ　Ｒｅｄ−５、２２、３８、４８：１、４８：２、４８：４、４９：１、５３：１、５７：１、６３：１、１４４、１４６、１８５、１０１、
Ｃ．Ｉ　Ｐｉｇｍｅｎｔ　Ｖｉｏｌｅｔ−１９、２３、
Ｃ．Ｉ　Ｐｉｇｍｅｎｔ　Ｂｌｕｅ−１５：１、１５：３、１５：４、１８、６０、２７、２９、
Ｃ．Ｉ　Ｐｉｇｍｅｎｔ　Ｇｒｅｅｎ−７、３６、
Ｃ．Ｉ　Ｐｉｇｍｅｎｔ　Ｗｈｉｔｅ−６、１８、２１、
Ｃ．Ｉ　Ｐｉｇｍｅｎｔ　Ｂｌａｃｋ−７
（白インク）
また、本発明において、プラスチックフィルムのような透明基材での色の隠蔽性を上げる為に、白インクを用いることが好ましい。特に、軟包装印刷、ラベル印刷においては、白インクを用いることが好ましいが、吐出量が多くなるため、前述した吐出安定性、記録材料のカール・皺の発生の観点から、自ずと使用量に関しては制限がある。
【０１１０】
上記顔料の分散には、例えば、ボールミル、サンドミル、アトライター、ロールミル、アジテータ、ヘンシェルミキサ、コロイドミル、超音波ホモジナイザー、パールミル、湿式ジェットミル、ペイントシェーカー等を用いることが出来る。また、顔料の分散を行う際に、分散剤を添加することも可能である。分散剤としては、高分子分散剤を用いることが好ましく、高分子分散剤としてはＡｖｅｃｉａ社のＳｏｌｓｐｅｒｓｅシリーズが挙げられる。また、分散助剤として、各種顔料に応じたシナージストを用いることも可能である。これらの分散剤及び分散助剤は、顔料１００質量％に対し、１〜５０質量％添加することが好ましい。分散媒体は、溶剤または重合性化合物を用いて行うが、本発明に用いる放射線硬化性インクでは、インク着弾直後に反応・硬化させるため、無溶剤であることが好ましい。溶剤が硬化画像に残ってしまうと、耐溶剤性の劣化、残留する溶剤のＶＯＣ（Ｖｏｌａｔｉｌｅ　Ｏｒｇａｎｉｃ　Ｃｏｍｐｏｕｎｄ；揮発性有機溶媒）の問題が生じる。よって、分散媒体は溶剤では無く重合性化合物、その中でも最も粘度の低いモノマーを選択することが分散適性上好ましい。
【０１１１】
顔料の分散は、顔料粒子の平均粒径を０．０８μｍ〜０．５μｍとすることが好ましく、最大粒径は０．３μｍ〜１０μｍ、好ましくは０．３μｍ〜３μｍとなるよう、顔料、分散剤、分散媒体の選定、分散条件、ろ過条件を適宜設定する。この粒径管理によって、ヘッドノズルの詰まりを抑制し、インクの保存安定性、インク透明性及び硬化感度を維持することが出来る。
【０１１２】
本発明に係るインクにおいては、色材濃度としては、インク全体の１質量％乃至１０質量％であることが好ましい。
【０１１３】
本発明に係るインクには、上記説明した以外に様々な添加剤を用いることが出来る。例えば、インク組成物の保存性を高めるため、重合禁止剤を２００〜２００００ｐｐｍ添加することが出来る。紫外線硬化型のインクは、加熱、低粘度化して射出することが好ましいので、熱重合によるヘッド詰まりを防ぐためにも重合禁止剤を入れることが好ましい。この他にも、必要に応じて、界面活性剤、レベリング添加剤、マット剤、膜物性を調整するためのポリエステル系樹脂、ポリウレタン系樹脂、ビニル系樹脂、アクリル系樹脂、ゴム系樹脂、ワックス類を添加することが出来る。記録媒体との密着性を改善するため、極微量の有機溶剤を添加することも有効である。この場合、耐溶剤性やＶＯＣの問題が起こらない範囲での添加が有効であり、その使用量は０．１〜５％の範囲であり、好ましくは０．１〜３％である。また、ラジカル重合性モノマーと開始剤を組み合わせ、ラジカル・カチオンのハイブリッド型硬化インクとすることも可能である。
【０１１４】
《画像形成方法》
本発明の画像形成方法について説明する。
【０１１５】
本発明の画像形成方法においては、上記のインク組成物をインクジェット記録方式により記録材料上に吐出、描画し、次いで紫外線などの活性光線を照射してインクを硬化させる方法が好ましい。
【０１１６】
（インク着弾後の総インク膜厚）
本発明では、記録材料上にインクが着弾し、活性光線を照射して硬化した後の総インク膜厚が２μｍ〜２０μｍであることが好ましい。スクリーン印刷分野の活性光線硬化型インクジェット記録では、総インク膜厚が２０μｍを越えているのが現状であるが、記録材料が薄いプラスチック材料であることが多い軟包装印刷分野では、前述した記録材料のカール・皺の問題でだけでなく、印刷物全体のこし・質感が変わってしまうという問題が有るため、過剰な膜厚のインク吐出は好ましくない。
【０１１７】
尚、ここで「総インク膜厚」とは記録材料に描画されたインクの膜厚の最大値を意味し、単色でも、それ以外の２色重ね（２次色）、３色重ね、４色重ね（白インクベース）のインクジェット記録方式で記録を行った場合でも総インク膜厚の意味するところは同様である。
【０１１８】
（インクの吐出条件）
インクの吐出条件としては、記録ヘッド及びインクを３５℃〜１００℃に加熱し、吐出することが吐出安定性の点で好ましい。活性光線硬化型インクは、温度変動による粘度変動幅が大きく、粘度変動はそのまま液滴サイズ、液滴射出速度に大きく影響を与え、画質劣化を起こすため、インク温度を上げながらその温度を一定に保つことが必要である。インク温度の制御幅としては、設定温度±５℃、好ましくは設定温度±２℃、更に好ましくは設定温度±１℃である。
【０１１９】
また、本発明では、各ノズルより吐出する液滴量が２ｐｌ〜１５ｐｌであることが好ましい。
【０１２０】
本来、高精細画像を形成するためには、液滴量がこの範囲であることが必要であるが、この液滴量で吐出する場合、前述した吐出安定性が特に厳しくなる。本発明によれば、インクの液滴量が２ｐｌ〜１５ｐｌのような小液滴量で吐出を行っても吐出安定性は向上し、高精細画像が安定して形成出来る。
【０１２１】
（インク着弾後の光照射条件）
本発明の画像記録方法においては、活性光線の照射条件として、インク着弾後０．００１秒〜２．０秒の間に活性光線が照射されることが好ましく、より好ましくは０．００１秒〜１．０秒である。高精細な画像を形成するためには、照射タイミングが出来るだけ早いことが特に重要となる。
【０１２２】
活性光線の照射方法として、その基本的な方法が特開昭６０−１３２７６７号に開示されている。これによると、ヘッドユニットの両側に光源を設け、シャトル方式でヘッドと光源を走査する。照射は、インク着弾後、一定時間を置いて行われることになる。更に、駆動を伴わない別光源によって硬化を完了させる。米国特許第６，１４５，９７９号では、照射方法として、光ファイバーを用いた方法や、コリメートされた光源をヘッドユニット側面に設けた鏡面に当て、記録部へＵＶ光を照射する方法が開示されている。本発明の画像形成方法においては、これらの何れの照射方法も用いることが出来る。
【０１２３】
また、活性光線を照射を２段階に分け、まずインク着弾後０．００１〜２．０秒の間に前述の方法で活性光線を照射し、かつ、全印字終了後、更に活性光線を照射する方法も好ましい態様の１つである。活性光線の照射を２段階に分けることで、よりインク硬化の際に起こる記録材料の収縮を抑えることが可能となる。
【０１２４】
従来、ＵＶインクジェット方式では、インク着弾後のドット広がり、滲みを抑制のために、光源の総消費電力が１ｋＷ・ｈｒを超える高照度の光源が用いられるのが通常であった。しかしながら、これらの光源を用いると、特に、シュリンクラベルなどへの印字では、記録材料の収縮があまりにも大きく、実質上使用出来ないのが現状であった。
【０１２５】
本発明では、２８０ｎｍ〜３２０ｎｍの波長領域に最高照度をもつ活性光線を用いることで、総消費電力が１ｋＷ・ｈｒ以上の光源を用いても、高精細な画像を形成出来、且つ、記録材料の収縮も実用上許容レベル内に収められる。
【０１２６】
本発明においては、更に活性光線を照射する光源の総消費電力が１ｋＷ・ｈｒ未満であることが好ましい。総消費電力が１ｋＷ・ｈｒ未満の光源の例としては、蛍光管、冷陰極管、ＬＥＤなどがあるが、これらに限定されない。
【０１２７】
《印刷物》
本発明の印刷物について説明する。
【０１２８】
本発明の印刷物は、非吸収性録材料上に、本発明の画像形成方法及び／または、本発明に記載の画像形成装置を用いて、作製されることが特徴である。ここで、非吸収性とは、インク組成物（単にインクともいう）を吸収しないと言う意味であり、本発明においては、下記に示すようなブリストウ法におけるインク転移量が、０．１ｍｌ／ｍｍ^２未満であり、実質的に０ｍｌ／ｍｍ^２であるようなものを非吸収性記録材料と定義する。
【０１２９】
《ブリストウ法》
本発明でいうブリストウ法とは、短時間での紙及び板紙の液体吸収挙動を測定する方法であり、詳しくは、Ｊ．ＴＡＰＰＩ紙パルプ試験方法Ｎｏ．５１−８７紙又は板紙の液体吸収性試験方法（ブリストウ法）に準じて測定し、接触時間４０ｍ秒におけるインク転移量（ｍｌ／ｍ^２）で表される。なお、上記の測定方法では、測定に純水（イオン交換水）が使用されているが、測定面積の判別を容易にするために、本発明においては、２％未満の水溶性染料を含有させてもよい。
【０１３０】
具体的な測定方法の一例を、以下に説明する。
インク転移量の測定法としては、記録媒体を２５℃、５０％ＲＨの雰囲気下で１２時間以上放置した後、例えば、熊谷理機工業株式会社製の液体動的吸収性試験機であるＢｒｉｓｔｏｗ試験機ＩＩ型（加圧式）を用いて測定する。測定に用いる液体は、測定精度を高めるため、市販の水系インクジェットインク（例えば、マゼンタインク）とし、規定の接触時間後に記録媒体上のマゼンタ染色された部分の面積を測定することにより、インク転移量を求めることができる。
【０１３１】
（非吸収性記録材料）
本発明に係る非吸収性記録材料としては、通常の非コート紙、コート紙などの他、いわゆる軟包装に用いられる各種非吸収性のプラスチックおよびそのフィルムを用いることができ、各種プラスチックフィルムとしては、例えば、ＰＥＴフィルム、ＯＰＳフィルム、ＯＰＰフィルム、ＯＮｙフィルム、ＰＶＣフィルム、ＰＥフィルム、ＴＡＣフィルムを挙げることができる。その他のプラスチックとしては、ポリカーボネート、アクリル樹脂、ＡＢＳ、ポリアセタール、ＰＶＡ、ゴム類などが使用できる。また、金属類や、ガラス類にも適用可能である。これらの記録材料の中でも、特に熱でシュリンク可能な、ＰＥＴフィルム、ＯＰＳフィルム、ＯＰＰフィルム、ＯＮｙフィルム、ＰＶＣフィルムへ画像を形成する場合に本発明の構成は、有効となる。これらの基材は、インクの硬化収縮、硬化反応時の発熱などにより、フィルムのカール、変形が生じやすいばかりでなく、インク膜が基材の収縮に追従し難い。
【０１３２】
これら、各種プラスチックフィルムの表面エネルギーは大きく異なり、記録材料によってインク着弾後のドット径が変わってしまうことが、従来から問題となっていた。本発明の構成では、表面エネルギーの低いＯＰＰフィルム、ＯＰＳフィルムや表面エネルギーの比較的大きいＰＥＴまでを含む、表面エネルギーが０．０３５Ｊ／ｍ^２〜０．０６Ｊ／ｍ^２のような広範囲の記録材料に良好な高精細な画像を形成できるが、本発明に記載の効果がより好ましく得られるのは、０．０４０Ｊ／ｍ^２〜０．０６Ｊ／ｍ^２の範囲の記録材料である。
【０１３３】
本発明において、包装の費用や生産コスト等の記録材料のコスト、プリントの作製効率、各種のサイズのプリントに対応できる等の点で、長尺（ウェブ）な記録材料を使用する方が有利である。
【０１３４】
【発明の実施の形態】
《記録装置》
本発明の記録装置について説明する。
【０１３５】
以下、本発明の記録装置について、図面を適宜参照しながら説明する。尚、図面の記録装置はあくまでも本発明の記録装置の一態様であり、本発明の記録装置はこの図面に限定されない。
【０１３６】
図１は本発明の記録装置の要部の構成を示す正面図である。記録装置１は、ヘッドキャリッジ２、記録ヘッド３、照射手段４、プラテン部５等を備えて構成される。この記録装置１は、記録材料Ｐの下にプラテン部５が設置されている。プラテン部５は、紫外線を吸収する機能を有しており、記録材料Ｐを通過してきた余分な紫外線を吸収する。その結果、高精細な画像を非常に安定に再現できる。
【０１３７】
記録材料Ｐは、ガイド部材６に案内され、搬送手段（図示せず）の作動により、図１における手前から奥の方向に移動する。ヘッド走査手段（図示せず）は、ヘッドキャリッジ２を図１におけるＹ方向に往復移動させることにより、ヘッドキャリッジ２に保持された記録ヘッド３の走査を行なう。
【０１３８】
ヘッドキャリッジ２は記録材料Ｐの上側に設置され、記録材料Ｐ上の画像印刷に用いる色の数に応じて後述する記録ヘッド３を複数個、吐出口を下側に配置して収納する。ヘッドキャリッジ２は、図１におけるＹ方向に往復自在な形態で記録装置１本体に対して設置されており、ヘッド走査手段の駆動により、図１におけるＹ方向に往復移動する。
【０１３９】
尚、図１ではヘッドキャリッジ２がホワイト（Ｗ）、イエロー（Ｙ）、マゼンタ（Ｍ）、シアン（Ｃ）、ブラック（Ｋ）、ライトイエロー（Ｌｙ）、ライトマゼンタ（Ｌｍ）、ライトシアン（Ｌｃ）、ライトブラック（Ｌｋ）、ホワイト（Ｗ）の記録ヘッド３を収納するものとして描図を行なっているが、実施の際にはヘッドキャリッジ２に収納される記録ヘッド３の色数は適宜決められるものである。
【０１４０】
記録ヘッド３は、インク供給手段（図示せず）により供給された活性光線硬化型インク（例えばＵＶ硬化インク）を、内部に複数個備えられた吐出手段（図示せず）の作動により、吐出口から記録材料Ｐに向けて吐出する。記録ヘッド３により吐出されるＵＶインクは色材、重合性モノマー、開始剤等を含んで組成されており、紫外線の照射を受けることで開始剤が触媒として作用することに伴なうモノマーの架橋、重合反応によって硬化する性質を有する。
【０１４１】
記録ヘッド３は記録材料Ｐの一端からヘッド走査手段の駆動により、図１におけるＹ方向に記録材料Ｐの他端まで移動するという走査の間に、記録材料Ｐにおける一定の領域（着弾可能領域）に対してＵＶインクをインク滴として吐出し、該着弾可能領域にインク滴を着弾させる。
【０１４２】
上記走査を適宜回数行ない、１領域の着弾可能領域に向けてＵＶインクの吐出を行なった後、搬送手段で記録材料Ｐを図１における手前から奥方向に適宜移動させ、再びヘッド走査手段による走査を行ないながら、記録ヘッド３により上記着弾可能領域に対し、図１における奥方向に隣接した次の着弾可能領域に対してＵＶインクの吐出を行なう。
【０１４３】
上述の操作を繰り返し、ヘッド走査手段及び搬送手段と連動して記録ヘッド３からＵＶインクを吐出することにより、記録材料Ｐ上にＵＶインク滴の集合体からなる画像が形成される。
【０１４４】
照射手段４は特定の波長領域の紫外線を安定した露光エネルギーで発光する紫外線ランプ及び特定の波長の紫外線を透過するフィルターを備えて構成される。ここで、紫外線ランプとしては、水銀ランプ、メタルハライドランプ、エキシマーレーザー、紫外線レーザー、冷陰極管、ブラックライト、ＬＥＤ（ｌｉｇｈｔｅｍｉｔｔｉｎｇ　ｄｉｏｄｅ）等が適用可能であり、帯状のメタルハライドランプ管、冷陰極管、水銀ランプ管もしくはブラックライトが好ましい。特に波長３６５ｎｍの紫外線を発光する冷陰極管及びブラックライトが滲み防止、ドット径制御を効率よく行なえ、かつ、硬化の際の皺も低減でき好ましい。ブラックライトを照射手段４の放射線源に用いることで、ＵＶインクを硬化するための照射手段４を安価に作製することができる。
【０１４５】
照射手段４は、記録ヘッド３がヘッド走査手段の駆動による１回の走査によってＵＶインクを吐出する着弾可能領域のうち、記録装置（ＵＶインクジェットプリンタ）１で設定できる最大のものとほぼ同じ形状か、着弾可能領域よりも大きな形状を有する。
【０１４６】
照射手段４はヘッドキャリッジ２の両脇に、記録材料Ｐに対してほぼ平行に、固定して設置される。
【０１４７】
前述したようにインク吐出部の照度を調整する手段としては、記録ヘッド３全体を遮光することはもちろんであるが、加えて照射手段４と記録材料Ｐの距離ｈ１より、記録ヘッド３のインク吐出部３１と記録材料Ｐとの距離ｈ２を大きくしたり（ｈ１＜ｈ２）、記録ヘッド３と照射手段４との距離ｄを離したり（ｄを大きく）することが有効である。又、記録ヘッド３と照射手段４の間を蛇腹構造７にすると更に好ましい。
【０１４８】
ここで、照射手段４で照射される紫外線の波長は、照射手段４に備えられた紫外線ランプ又はフィルターを交換することで適宜変更することができる。
【０１４９】
記録材料としては、通常の非コート紙、コート紙などの他、いわゆる軟包装に用いられる各種非吸収性のプラスチック及びそのフィルムを用いることが出来る。各種プラスチックフィルムとしては、例えばＰＥＴ（ポリエチレンテレフタレート）フィルム、ＯＰＳ（延伸ポリスチレン）フィルム、ＯＰＰ（延伸ポリプロピレン）フィルム、ＯＮｙ（延伸ナイロン）フィルム、ＰＶＣ（ポリビニルクロライド）フィルム、ＰＥフィルム、ＴＡＣフィルムがある。その他のプラスチックとしては、ポリカーボネート、アクリル樹脂、ＡＢＳ、ポリアセタール、ＰＶＡ、ゴム類などが使用出来る。又、金属類や、ガラス類にも適用可能である。
【０１５０】
これらの記録材料の中でも、特に熱でシュリンク可能な、ＰＥＴフィルム、ＯＰＳフィルム、ＯＰＰフィルム、ＯＮｙフィルム、ＰＶＣフィルムへ画像を形成する場合、本発明の効果は更に有効となる。これらの基材は、インクの硬化収縮、硬化反応時の発熱などにより、フィルムのカール、変形が生じやすいばかりでなく、インク膜が基材の収縮に追従し難い。
【０１５１】
本発明において、包装の費用や生産コスト等の記録材料のコスト、プリントの作成効率、各種のサイズのプリントに対応できる等の点で、長尺（ウェブ）な記録材料を使用する方が有利である。
【０１５２】
【実施例】
以下、実施例により本発明を説明するが、本発明はこれらに限定されない。
【０１５３】
実施例１
《インク組成物の調製》
表１〜３に記載の構成からなるインク組成物１〜３を調製した。尚、表１はインク組成物１、表２はインク組成物２、表３はインク組成物３をそれぞれ示す。
【０１５４】
【表１】

【０１５５】
【表２】

【０１５６】
【表３】

【０１５７】
表１〜３に記載のインクの略称及び各化合物の詳細は、以下の通りである。
Ｋ：濃ブラックインク
Ｃ：濃シアンインク
Ｍ：濃マゼンタインク
Ｙ：濃イエローインク
Ｌｋ：淡ブラックインク
Ｌｃ：淡シアンインク
Ｌｍ：淡マゼンタインク
Ｌｙ：淡イエローインク
色材１：Ｃ．Ｉ．ｐｉｇｍｅｎｔ　Ｂｌａｃｋ　７
色材２：Ｃ．Ｉ．ｐｉｇｍｅｎｔ　Ｂｌｕｅ　１５：３
色材３：Ｃ．Ｉ．ｐｉｇｍｅｎｔ　Ｒｅｄ　５７：１
色材４：Ｃ．Ｉ．ｐｉｇｍｅｎｔ　Ｙｅｌｌｏｗ　１３
光ラジカル重合性化合物１：ラウリルアクリレート（単官能）
光ラジカル重合性化合物２：ビスフェノールＡグリシジルエーテルメタクリル酸付加体（二官能）
光ラジカル重合性化合物３：テトラエチレングリコールジアクリレート（二官能）
光ラジカル重合性化合物４：トリメチロールプロパントリアクリレート（三官能）
光ラジカル重合性化合物５：カプロラクタム変性ジペンタエリスリトールヘキサアクリレート（六官能）
光ラジカル発生剤１：イルガキュア６５１（チバ・スペシャルティ・ケミカルズ社製）
光ラジカル発生剤２：イルガキュア３６９（チバ・スペシャルティ・ケミカルズ社製）
開始剤助剤：ジエチルチオキサントン
マレイミド化合物１：（ＬＵＭＩＣＵＲＥ　ＭＩＡ２００　ＤＩＣ社製）
３級アミノ化合物：ＥＰＡ（ｐ−ジメチルアミノ安息香酸エチル）（日本化薬製）
《インクジェット画像形成方法》
ピエゾ型インクジェットノズルを備えた、図１に記載のようなインクジェット記録装置に、上記調製した各インク組成物を装填し、表４に記載の表面エネルギーをもつ巾６００ｍｍ、長さ１０００ｍの長尺の各記録材料へ下記の各画像記録を連続して行った。インク供給系は、インクタンク、供給パイプ、ヘッド直前の前室インクタンク、フィルター付き配管、ピエゾヘッドからなり、ピエゾヘッド部は、３０℃に温度調整した。ピエゾヘッド部は、２ｐｌ〜１５ｐｌのマルチサイズドットを７２０ｄｐｉ×７２０ｄｐｉ（ｄｐｉとは、２．５４ｃｍ当たりのドット数を表す。）の解像度で吐出出来るよう駆動して、各インクを連続吐出した。着弾した後、０．２秒後に、表４に記載の照射条件で硬化処理を行った。記録後、総インク膜厚を測定したところ、２．３μｍ〜１３μｍの範囲であった。
【０１５８】
【表４】

【０１５９】
（１）表４に記載の各記録材料の略称の詳細は、以下の通りである。
ＯＰＰ：ｏｒｉｅｎｔｅｄ　ｐｏｌｙｐｒｏｐｙｌｅｎｅ
ＰＥＴ：ｐｏｌｙｅｔｈｙｌｅｎｅ　ｔｅｒｅｐｈｔｈａｌａｔｅ
ＯＮｙ：ｏｒｉｅｎｔｅｄ　ｎｙｌｏｎ
ＰＶＣ：ｐｏｌｙｖｉｎｙｌｃｈｌｏｒｉｄｅ
（２）表４に記載の照射光源の詳細は、以下の通りである。
【０１６０】
照射光源１：無電源ＵＶランプ（フュージョンＵＶシステムズ・ジャパン社製
Ｆ４５０シリーズ　電力：３ｋＷ・ｈｒ）
照射光源２：冷陰極管（ハイベック社製の特注品　電力：１ｋＷ・ｈｒ未満）
照射光源３：蛍光灯（ニッポ電気社製の特注品　電力：１ｋＷ・ｈｒ未満）
（３）照射タイミング：全て、着弾した後０．２秒後
（４）照射方法
照射光源１：記録ヘッド両横・線光源照射
照射光源２：記録ヘッド両横・線光源１０本づつで照射
照射光源３：記録ヘッド両横・線光源３本づつで照射
（５）記録材料面上の最高照度とそのピーク波長
照射光源１：３６５ｎｍのピーク波長で７００ｍＷ／ｃｍ^２
照射光源２：３０８ｎｍのピーク波長で１５ｍＷ／ｃｍ^２
照射光源３：３１０ｎｍのピーク波長で１０ｍＷ／ｃｍ^２
（６）露光エネルギーとそのピーク波長
照射光源１：３６５ｎｍのピーク波長で２００ｍＪ／ｃｍ^２
照射光源２：３０８ｎｍのピーク波長で４０ｍＪ／ｃｍ^２
照射光源３：３１０ｎｍのピーク波長で３０ｍＪ／ｃｍ^２
《インクジェット記録画像の評価》
上記画像形成方法で記録した各画像について、下記の各評価を行った。尚、各評価は、連続吐出した画像記録の印字後１０ｍの試料、１００ｍの試料及び５００ｍの試料について行った。得られた各評価結果を、表５に示す。
【０１６１】
《文字品質の評価》
Ｙ、Ｍ、Ｃ、Ｋの各色を、目標とする濃度で６ポイントＭＳ明朝体文字を印字し、文字のガサツキをルーペで拡大観察し、下記の基準に則り文字品質をランク評価した。
【０１６２】
◎：ガサツキがない
○：僅かにガサツキが認められる
△：ガサツキが認められるが、文字として判別出来る
×：ガサツキが激しく、文字がかすれていて使用に耐えないレベルである
《色混じり（滲み）の評価》
印字した高精細画像中の隣り合う各色ｄｏｔをルーペで拡大して滲み具合を目視観察し、下記の基準に則り色混じりの評価を行った。
【０１６３】
◎：隣り合うｄｏｔ形状が真円を保ち、滲みがない
○：隣り合うｄｏｔ形状はほぼ真円を保ち、ほとんど滲みがない
△：隣り合うｄｏｔが少し滲んでいてｄｏｔ形状が少しくずれているが、許容範囲のレベルである
×：隣り合うｄｏｔが滲んで混じりあっており、使用に耐えないレベルである
《印刷物皺、カールの評価》
１０ｍ、１００ｍ及び５００ｍ印字した後、各印刷物について、照射・硬化により皺やカールが発生していないかを目視観察し、下記の評価基準に則り評価した。
【０１６４】
○：皺やカールの発生が無く、良好である
△：やや皺やカールの発生が認められるが、実用上許容の範囲にある
×：印刷物に強い皺やカールが認められ、実用上問題となる
【０１６５】
【表５】

【０１６６】
表５より、比較に比べて本発明の試料は、文字品質に優れ、色混じりの発生もなく、高精細な画像を記録することが出来、且つ、印刷物の皺やカールの発生が無いことが明らかである。
【０１６７】
実施例２
《インク組成物の調製》
表６〜８に記載の構成からなるインク組成物４〜６を調製した。尚、表６はインク組成物４、表７はインク組成物５、表８はインク組成物６をそれぞれ示す。
【０１６８】
【表６】

【０１６９】
【表７】

【０１７０】
【表８】

【０１７１】
表６〜８に記載の各化合物の詳細は、以下の通りである。
Ｋ：濃ブラックインク
Ｃ：濃シアンインク
Ｍ：濃マゼンタインク
Ｙ：濃イエローインク
Ｌｋ：淡ブラックインク
Ｌｃ：淡シアンインク
Ｌｍ：淡マゼンタインク
Ｌｙ：淡イエローインク
Ｗ：ホワイトインク
色材１：Ｃ．Ｉ．ｐｉｇｍｅｎｔ　Ｂｌａｃｋ　７
色材２：Ｃ．Ｉ．ｐｉｇｍｅｎｔ　Ｂｌｕｅ　１５：３
色材３：Ｃ．Ｉ．ｐｉｇｍｅｎｔ　Ｒｅｄ　５７：１
色材４：Ｃ．Ｉ．ｐｉｇｍｅｎｔ　Ｙｅｌｌｏｗ　１３
色材５：酸化チタン（アナターゼ型　平均粒径０．２０μｍ）
光カチオン重合性化合物１（エポキシ化合物）：セロキサイド３０００（ダイセル化学工業社製）
光カチオン重合性化合物２（オキセタン化合物）：ＯＸＴ−２２１（東亜合成化学社製）
光カチオン重合性化合物３（オキセタン化合物）：ＯＸＴ−２１２（東亜合成化学社製）
光カチオン重合性化合物４（オキセタン化合物）：ＯＸＴ−２１１（東亜合成化学社製）
光カチオン重合性化合物５（オキセタン化合物）：ＤＡＩＭＩＣ　Ｓ３００Ｋ（ダイセル化学工業社製）
酸増殖剤１：化合物１
酸増殖剤２：化合物２
塩基性化合物１：Ｎ−エチルジエタノールアミン
塩基性化合物２：トリプロピルアミン
熱塩基発生剤１：下記構造式
熱塩基発生剤２：下記構造式
光酸発生剤１：ＣＳ５１０２（日本曹達社製）
光酸発生剤２：ＳＰ１５２（旭電化工業社製）
開始剤助剤：ＣＩ７００１（日本曹達社製）
【０１７２】
【化２０】

【０１７３】
マレイミド化合物２：下記構造式
【０１７４】
【化２１】

【０１７５】
《マレイミド化合物２の合成》
ステップ１：マレイミド酢酸の合成
滴下ロート、冷却管及び攪拌機を備えた容量１リットルの三口フラスコに、グリシン３７．５ｇ及び４００ｍｌの酢酸を仕込み、室温条件下に攪拌しながら、無水マレイン酸４９．０ｇ及び酢酸３００ｍｌからなる溶液を滴下ロートから２時間かけて滴下した。滴下終了後、更に１時間攪拌を続けた後、反応を終了させた。生じた沈殿を濾取し、水：メタノール＝３：７（容量比）の混合溶媒中から再結晶させてマレイミド酢酸１１ｇを得た。
【０１７６】
（マレイミド酢酸の物性値）
（^１Ｈ−ＮＭＲ測定）：測定条件（３００ＭＨｚ、ＤＭＳＯ−ｄ６）
７．０ｐｐｍ（ｓ、２Ｈ、−Ｃ＝Ｃ−）
４．１ｐｐｍ（ｓ、２Ｈ、−ＣＨ_２−）
（ＩＲ測定）
３１７０ｃｍ^−１（−ＣＯＯＨ）
１７５０ｃｍ^−１、１７１９ｃｍ^−１（Ｃ＝Ｏ）
８３１ｃｍ^−１、６９６ｃｍ^−１（−Ｃ＝Ｃ−）
（元素分析）：測定対象元素（ＣＨＮ）
計算値：Ｃ４６．５％、Ｈ３．８７％、Ｎ９．０３％
分析値：Ｃ４６．２％、Ｈ４．０５％、Ｎ８．７０％
ステップ２：マレイミド酢酸合成
続いて、ディーンスターク型分留器を備えた容量２００ｍｌのナス型フラスコに、数平均分子量２５０のポリテトラメチレングリコール（ビー・エー・エス・エフ・ジャパン社製の「ポリ（Ｐｏｌｙ）ＴＨＦ２５０」、ＧＰＣによるポリスチレン換算値：数平均分子量４４０、重量平均分子量４７０）５ｇ、上記で得たマレイミド酢酸６．８ｇ、ｐ−トルエンスルホン酸１．２ｇ、２，６−ｔｅｒｔ−ブチル−ｐ−クレゾール０．０６ｇ及びトルエン１５ｍｌを仕込み、３２０００Ｐａ、８０℃の条件で生成する水を除去しながら、４時間攪拌し続けて反応を続けた。反応混合物をトルエン２００ｍｌに溶解し、飽和炭酸水素ナトリウム１００ｍｌで３回、飽和食塩水１００ｍｌで１回洗浄した。有機相を濃縮して下記式で表わされるマレイミド化合物２の淡黄色液体９ｇを得た。
【０１７７】
（マレイミド化合物２の物性値）
（ＩＲ）
１７５０ｃｍ^−１、１７１９ｃｍ^−１（Ｃ＝Ｏ）
８３１ｃｍ^−１、６９８ｃｍ^−１（Ｃ＝Ｃ）
（^１Ｈ−ＮＭＲ）：測定条件（３００ＭＨｚ，ＣＤＣｌ_３）
６．７ｐｐｍ（ｓ，４Ｈ，−ＣＨ＝ＣＨ−）
４．３ｐｐｍ［ｓ，４Ｈ，Ｎ−ＣＨ_２−（Ｃ＝Ｏ）−］
４．１ｐｐｍ（ｔ，４Ｈ，−（Ｃ＝Ｏ）−Ｏ−ＣＨ_２−）
３．４〜３．５ｐｐｍ（ｍ，−Ｏ−ＣＨ_２−）
１．６〜１．７ｐｐｍ（ｍ，−ＣＨ_２−）
（^１３Ｃ−ＮＭＲ）：測定条件（７５ＭＨｚ，ＣＤＣｌ_３）
１７０ｐｐｍ［Ｎ−（Ｃ＝Ｏ）］
１６７ｐｐｍ［−（Ｃ＝Ｏ）−Ｏ］
１３５ｐｐｍ（−ＣＨ＝ＣＨ−）
６４．５〜７０．９ｐｐｍ（−Ｏ−ＣＨ_２−）
３８．７ｐｐｍ（Ｎ−ＣＨ_２−）
２５．７〜２６．６ｐｐｍ（−ＣＨ_２−）
（ＧＰＣによる分子量分布分析結果（ポリスチレン換算））
数平均分子量７３０、重量平均分子量７５０
《インクジェット画像形成方法》
ピエゾ型インクジェットノズルを備えた、図１に記載のようなインクジェット記録装置に、上記調製した各インク組成物を装填し、表９に記載の表面エネルギーをもつ巾６００ｍｍ、長さ１０００ｍの長尺の各記録材料へ下記の各画像記録を連続して行った。インク供給系は、インクタンク、供給パイプ、ヘッド直前の前室インクタンク、フィルター付き配管、ピエゾヘッドからなり、ピエゾヘッド部は、５０℃に温度調整した。ピエゾヘッド部は、２ｐｌ〜１５ｐｌのマルチサイズドットを７２０ｄｐｉ×７２０ｄｐｉの解像度で吐出出来るよう駆動して、各インクを連続吐出した。着弾した後、０．１５秒後に、表９に記載の照射条件で硬化処理を行った。記録後、トータルインク膜厚を測定したところ、２．３μｍ〜１９．６μｍの範囲であった。
【０１７８】
【表９】

【０１７９】
（１）表９に記載の各記録材料の略称の詳細は、以下の通りである。
ＯＰＰ：ｏｒｉｅｎｔｅｄ　ｐｏｌｙｐｒｏｐｙｌｅｎｅ
ＰＥＴ：ｐｏｌｙｅｔｈｙｌｅｎｅ　ｔｅｒｅｐｈｔｈａｌａｔｅ
ＯＮｙ：ｏｒｉｅｎｔｅｄ　ｎｙｌｏｎ
シュリンクＰＶＣ：市販のシュリンク用途のｐｏｌｙｖｉｎｙｌｃｈｌｏｒｉｄｅ
シュリンクＯＰＳ：市販のシュリンク用途のｏｒｉｅｎｔｅｄ　ｐｏｌｙｓｔｙｒｅｎｅ
（２）表９に記載の照射光源の詳細は、以下の通りである。
【０１８０】
照射光源４：ブラックライト（ニッポ電気社製の特注品　電力：１ｋＷ・ｈｒ未満）
照射光源５：冷陰極管（ハイベック社製の特注品　電力：１ｋＷ・ｈｒ未満）
照射光源６：ＬＥＤ（日亜化学工業社製の特注品　電力：１ｋＷ・ｈｒ未満）
（３）照射タイミング：全て、着弾した後０．１５秒後
（４）照射方法
照射光源４：記録ヘッド両横・線光源３本づつで照射
照射光源５：記録ヘッド両横・線光源１０本づつで照射
照射光源６：記録ヘッド両横・線光源３本づつで照射
（５）記録材料面上の最高照度とそのピーク波長
照射光源４：３６５ｎｍのピーク波長で１０ｍＷ／ｃｍ^２
照射光源５：３０８ｎｍのピーク波長で１５ｍＷ／ｃｍ^２
照射光源６：３１０ｎｍのピーク波長で１０ｍＷ／ｃｍ^２
（６）露光エネルギーとそのピーク波長
照射光源４：３６５ｎｍのピーク波長で３５ｍＪ／ｃｍ^２
照射光源５：３０８ｎｍのピーク波長で４０ｍＪ／ｃｍ^２
照射光源６：３１０ｎｍのピーク波長で３０ｍＪ／ｃｍ^２
《インクジェット記録画像の評価》
上記画像形成方法で記録した各画像について、連続吐出した画像記録の印字後１０ｍの試料、１００ｍの試料及び５００ｍの試料について、実施例１に記載の方法と同様にして、文字品質、色混じり及び印刷物皺、カールの評価を行い、得られた結果を表１０に示す。
【０１８１】
【表１０】

【０１８２】
表１０より、比較に比べて本発明の試料は、文字品質に優れ、色混じりの発生もなく、高精細な画像を記録することが出来、且つ、印刷物の皺やカールの発生が無いことが明らかである。
【０１８３】
【発明の効果】
本発明により、あらゆる記録材料に対し、文字品質に優れ、色混じりの発生がなく、高精細な画像を記録することが出来、且つ、印刷物の皺やカールの発生が無い画像形成方法、印刷物及び記録装置を提供することが出来た。
【図面の簡単な説明】
【図１】本発明の記録装置の要部の構成を示す正面図である。
【符号の説明】
１　記録装置
２　ヘッドキャリッジ
３　記録ヘッド
４　照射手段
５　プラテン部
６　ガイド部材
７　蛇腹構造
Ｐ　記録材料[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming method, a printed matter, and a recording device.
[0002]
[Prior art]
In recent years, the ink jet recording method has been applied to various printing fields such as photographs, various printings, special printings such as markings and color filters, since images can be easily and inexpensively formed. In particular, a recording device that emits and controls fine dots, and ink with improved color gamut, durability, ejection suitability, etc., ink absorptivity, coloring of coloring materials, surface gloss, etc. have been dramatically improved. Using special paper, it is also possible to obtain image quality comparable to silver halide photography. Improvement in image quality of today's ink jet recording system has been achieved only when all of the recording device, ink, and special paper are provided.
[0003]
However, an ink jet system that requires special paper has a problem that the recording medium is limited and the cost of the recording medium is increased. Therefore, many attempts have been made to perform recording on a transfer-receiving medium different from dedicated paper by an inkjet method. Specifically, a phase-change inkjet method using a wax ink that is solid at room temperature, a solvent-based inkjet method using a fast-drying organic solvent-based ink, and a UV inkjet method that performs crosslinking by ultraviolet (UV) light after recording. It is.
[0004]
Above all, the UV inkjet system has been attracting attention in recent years in that it has a relatively low odor compared to the solvent-based inkjet system, and is capable of recording on a recording medium that is quick drying and has no ink absorption. JP-A-54667, JP-A-6-200204, and JP-T-2000-504778 disclose an ultraviolet-curable inkjet ink.
[0005]
However, even if these inks are used, the dot diameter after landing greatly changes depending on the type of recording material and the working environment, and it is not possible to form a high-definition image on all recording materials. It is possible.
[0006]
In addition, the ink used in the conventional UV inkjet method has a problem that the recording material is easily shrunk. In particular, thin-film plastic films used in flexible packaging such as food packaging and adhesive labels are particularly susceptible to shrinkage. As a result, the UV inkjet method has not yet been put to practical use in flexible packaging printing and label printing. is the current situation.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide an image forming method which is capable of recording a high-definition image with excellent character quality, no color mixing, and high wrinkles and curling of printed matter, for any recording material, It is to provide a printed matter and a recording device.
[0008]
[Means for Solving the Problems]
The above object of the present invention has been achieved by the following configurations.
[0009]
1. An image forming method in which an ink curable by actinic light is ejected onto a recording material by a recording head having at least one nozzle capable of selectively controlling ejection of ink droplets, wherein the ink contains a compound containing a maleimide skeleton. And curing the ink using an actinic ray having the highest illuminance in the wavelength range of 280 nm to 320 nm.
[0010]
2. A recording apparatus having at least one nozzle capable of selectively controlling the ejection of ink droplets, and a recording apparatus for forming an image by ejecting an ink that is cured by actinic rays onto a recording material. A recording apparatus, comprising: curing an ink using an actinic ray containing a compound having a maleimide skeleton and having maximum illuminance in a wavelength range of 280 nm to 320 nm.
[0011]
Preferred embodiments of the above configuration of the present invention will be described below.
1) Irradiation with actinic rays for 0.001 to 2.0 seconds after the ink has landed; 2) Total ink film thickness after the ink has landed and has been cured by irradiation with actinic rays. 3) The amount of ink droplets ejected from each nozzle of the recording head is 2 to 15 pl, 4) At least one color of the ink is white ink, 5) The ink contains at least one photoacid generator and a cationic polymerizable monomer; 6) the ink contains at least one photoradical generator and a radical polymerizable monomer; 7) the maleimide The compound having a skeleton is represented by the general formula (A).
[0012]
The printed matter obtained by the above-described image forming method uses a non-absorbing recording material. In particular, the surface energy of the non-absorbing recording material is 35 mJ / m.²~ 60mJ / m²It is preferable that
[0013]
In the image forming method of the present invention, the ink composition is ejected onto a recording material by an ink jet recording method, drawing is performed, and the ink is cured by irradiation with actinic rays such as ultraviolet rays.
[0014]
In the image forming method of the present invention, 1) an ink containing a compound having a maleimide skeleton is used, and 2) the ink discharged onto the recording material is hardened with active light having the highest illuminance in a wavelength range of 280 nm to 320 nm. It is characteristic.
[0015]
The image forming method of the present invention and a recording apparatus adopting the image forming method are particularly effective when discharging a large amount of white ink.
[0016]
The present inventors have aimed to reduce the occurrence of curling or wrinkling of a recording material due to ink shrinkage that occurs during ink curing in actinic ray-curable inkjet recording in which the thickness of a printed ink is thicker than that in normal printing. As a result of intensive studies, it has been newly found that if the ink ejected is cured using an active light beam having the highest illuminance in the wavelength range of 280 nm to 320 nm, the above-described problems that occur during ink curing can be improved. This has led to the present invention.
[0017]
In the conventional actinic ray curable ink jet recording, a high-pressure mercury lamp or a metal halide lamp has been used to cure the ink. However, these rays have a large illuminance wavelength peak around 365 nm and around 254 nm. In the field of packaging printing and label printing, from the viewpoint that wrinkles and curls occur in the recording material to be discharged, actinic ray-curable inkjet recording has not yet been put to practical use. The provision of the means 1) and 2) described above makes it possible to exert sufficient effects in those fields.
[0018]
A compound containing a maleimide skeleton (hereinafter, also referred to as a maleimide compound) that can be used in the present invention will be described. Examples of the maleimide compound used in the present invention include, for example, JP-A-2000-212249, JP-A-2000-143729, JP-A-2000-144403, JP-A-2000-144401, JP-A-2000-264922, JP-A-11-292874 and JP-A-11-124404. And maleimide compounds having various structures already known as disclosed in JP-A Nos. 11-124403 and 11-302278 can be used.
[0019]
The maleimide compound suitably used in the present invention includes a maleimide compound represented by the general formula (A).
[0020]
In the general formula (A), m and n each independently represent an integer of 1 or more. In particular, from the viewpoint of imparting the function of forming a cured film by itself at room temperature, compounds in which m and n are independent integers of 1 to 5 and m + n is an integer of 2 or more and 6 or less are recommended. Is done.
[0021]
R₁₁And R₁₂Represents a divalent group having an aliphatic group or an aromatic group each independently. Among them, a divalent group selected from the group consisting of an alkylene group, a cycloalkylene group, an arylalkylene group and a cycloalkylalkylene group is particularly preferred.
[0022]
Here, the alkylene group may be linear or branched, and the arylalkylene group or the cycloalkylalkylene group may have an aryl group or a cycloalkyl group in a main chain or a branched chain, respectively. You may have.
[0023]
R₁₁And R₁₂Specific examples of the divalent group having an aliphatic group or an aromatic group represented by: methylene group, ethylene group, trimethylene group, tetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group Linear alkylene groups such as octamethylene group, nonamethylene group, decamethylene group, undecamethylene group, dodecamethylene group; 1-methylethylene group, 1-methyl-trimethylene group, 2-methyl-trimethylene group, 1-methyl An alkylene group having a branched alkyl group such as a tetramethylene group, a 2-methyl-tetramethylene group, a 1-methyl-pentamethylene group, a 2-methyl-pentamethylene group, a 3-methyl-pentamethylene group, a neopentyl group; Cycloalkylene groups such as pentylene and cyclohexylene; benzylene, 2 Arylalkylene groups having an aryl group in the main chain or side chain, such as 2-diphenyl-trimethylene group, 1-phenyl-ethylene group, 1-phenyl-tetraethylene group, 2-phenyl-tetraethylene group; cyclohexylmethylene group, 1 A cycloalkylalkylene group having a cycloalkyl group in a main chain or a side chain such as a -cyclohexyl-ethylene group, a 1-cyclohexyl-tetraethylene group, or a 2-cyclohexyl-tetraethylene group, but the present invention is not limited thereto. Not done.
[0024]
R₂Is an average molecular weight of 40 to 40 in which an aliphatic group or an aromatic group is linked by at least one bond selected from the group consisting of (a) an ether bond, (b) an ester bond, (c) a urethane bond, and (d) a carbonate bond. 100,000 (A) (poly) ether tethers or (poly) ether residues, (B) (poly) ester tethers or (poly) ester tethers, (C) (poly) urethane tethers or (poly) ) Represents a urethane residue or (D) a (poly) carbonate connecting chain or a (poly) carbonate residue.
[0025]
R₂May be a connecting chain composed of an oligomer or a polymer in which these connecting chains are repeated as one unit.
[0026]
R₂Specific examples of the linking chain or the residue representing the following include, but are not limited to, the following.
[0027]
(A) average molecular weight in which at least one hydrocarbon group selected from the group consisting of a linear alkylene group, a branched alkylene group, a cycloalkylene group, and an aryl group has one or a repeating unit thereof bonded by an ether bond; Linking chains or residues composed of 40-100,000 (poly) ether (poly) ols:
(B) an average molecular weight in which at least one hydrocarbon group selected from the group consisting of a linear alkylene group, a branched alkylene group, a cycloalkylene group, and an aryl group has one or a repeating unit thereof bonded by an ester bond; Linking chains or residues composed of 40-100,000 (poly) ester (poly) ols:
(C) an average molecular weight in which at least one hydrocarbon group selected from the group consisting of a linear alkylene group, a branched alkylene group, a cycloalkylene group, and an aryl group has one or a repeating unit thereof bonded by an ether bond; The terminal is a polycarboxylic acid residue obtained by esterifying 40 to 100,000 (poly) ether (poly) ol with di-hexa-carboxylic acid (hereinafter abbreviated as polycarboxylic acid) (polycarboxylic acid residue). ) Linking chains or residues composed of carboxylic acid {(poly) ether (poly) ol} ester:
(D) at least one hydrocarbon group selected from the group consisting of a straight-chain alkylene group, a branched alkylene group, a cycloalkylene group, and an aryl group is bonded by an ether bond and an ester bond or a repeating unit thereof; (Poly) carboxylic acid ｛(poly) ester (poly) having a polycarboxylic acid residue at the end obtained by esterifying (poly) ester (poly) ol having an average molecular weight of 40 to 100,000 and polycarboxylic acid Linking chain or residue composed of all diester: (e) at least one hydrocarbon group selected from the group consisting of a linear alkylene group, a branched alkylene group, a cycloalkylene group, and an aryl group is bonded by an ether bond (Poly) epoxy having an average molecular weight of 100 to 40,000 having one or a repeating unit thereof Connecting chain or residue obtained by ring-opening a:
(F) an average molecular weight in which at least one hydrocarbon group selected from the group consisting of a linear alkylene group, a branched alkylene group, a cycloalkylene group, and an aryl group has one or a repeating unit thereof bonded by an ether bond; Linking chains or residues composed of (poly) ether (poly) isocyanate obtained by urethanizing 40 to 100,000 (poly) ether (poly) ol and organic (poly) isocyanate:
(G) an average molecular weight in which at least one hydrocarbon group selected from the group consisting of a linear alkylene group, a branched alkylene group, a cycloalkylene group, and an aryl group has one or a repeating unit thereof bonded by an ester bond; Linking chains or residues composed of (poly) ester (poly) isocyanate obtained by urethane-forming 40 to 100,000 (poly) ester (poly) ol and organic (poly) isocyanate:
(H) an average molecular weight in which at least one hydrocarbon group selected from the group consisting of a linear alkylene group, a branched alkylene group, a cycloalkylene group, and an aryl group has one or a repeating unit thereof bonded by an ether bond; Linking chains or residues composed of 40-100,000 (poly) ether (poly) ol carbonates:
Examples of the (poly) ether (poly) ol constituting the linking chain or the residue (a) include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetramethylene glycol; Modified ethylene oxide of alkylene glycols such as propanediol, propylene glycol, tetramethylene glycol, pentamethylene glycol, hexanediol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, diglycerin, ditrimethylolpropane, and dipentaerythritol , Propylene oxide-modified, butylene oxide-modified, tetrahydrofuran-modified, and the like. Various modified products of glycols are preferred.
[0028]
Further, as the (poly) ether (poly) ol constituting the linking chain (a), a copolymer of ethylene oxide and propylene oxide, a copolymer of propylene glycol and tetrahydrofuran, a copolymer of ethylene glycol and tetrahydrofuran, Hydrocarbon polyols such as polyisoprene glycol, hydrogenated polyisoprene glycol, polybutadiene glycol, and hydrogenated polybutadiene glycol; and polyhydric hydroxyl compounds such as polytetramethylene hexaglyceryl ether (tetrahydrofuran-modified hexaglycerin). However, it is not limited to these.
[0029]
Examples of the (poly) ester (poly) ol constituting the linking chain or the residue (b) include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polybutylene glycol and polytetramethylene glycol, and ethylene glycol. Ε-alkylene glycols such as propanediol, propylene glycol, tetramethylene glycol, pentamethylene glycol, hexanediol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, diglycerin, ditrimethylolpropane, and dipentaerythritol. Modified caprolactone, modified γ-butyrolactone, modified δ-valerolactone or modified methylvalerolactone; adipic acid, dimer acid Aliphatic polyester polyols which are esterified products of aliphatic dicarboxylic acids and polyols such as neopentyl glycol and methylpentanediol; aromatics which are esterified products of aromatic dicarboxylic acids such as terephthalic acid and polyols such as neopentyl glycol Polyester polyols such as aromatic polyester polyols; polyhydric hydroxyl compounds such as polycarbonate polyols, acrylic polyols, and polytetramethylene hexaglyceryl ether (tetrahydrofuran-modified hexaglycerin); fumaric acid, phthalic acid, isophthalic acid, itaconic acid, and adipic acid Esterified with dicarboxylic acids such as glycerol, sebacic acid and maleic acid; obtained by transesterification of polyhydric hydroxyl-containing compounds such as glycerin with fatty acid esters of animals and plants. Such polyhydric hydroxyl group-containing compound of monoglycerides, and the like, but not limited thereto.
[0030]
Examples of the (poly) carboxylic acid {(poly) ether (poly) ol} ester in which the terminal constituting the linking chain or the residue (c) is a polycarboxylic acid include (1) succinic acid, adipic acid, Phthalic acid, hexahydrophthalic acid, tetrahydrophthalic acid, fumaric acid, isophthalic acid, itaconic acid, adipic acid, sebacic acid, maleic acid, trimellitic acid, pyromellitic acid, benzenepentacarboxylic acid, benzenehexacarboxylic acid, citric acid (2) the terminal obtained by esterification of a polycarboxylic acid such as tetrahydrofurantetracarboxylic acid or cyclohexanetricarboxylic acid with the (poly) ether (poly) ol shown in the above (a) is a polycarboxylic acid (poly ) Carboxylic acid {(poly) ether (poly) ol} ester, But it is not limited to these.
[0031]
Examples of the (poly) carboxylic acid {(poly) ester (poly) ol} ester in which the terminal constituting the linking chain or the residue (d) is a polycarboxylic acid include (1) succinic acid, adipic acid, Phthalic acid, hexahydrophthalic acid, tetrahydrophthalic acid, fumaric acid, isophthalic acid, itaconic acid, adipic acid, sebacic acid, maleic acid, trimellitic acid, pyromellitic acid, benzenepentacarboxylic acid, benzenehexacarboxylic acid, citric acid (2) Esterification of di-hexa-carboxylic acid such as tetrahydrofurantetracarboxylic acid or cyclohexanetricarboxylic acid with (poly) ester (poly) ol shown in (b) above, the terminal being polycarboxylic acid (Poly) carboxylic acid {(poly) ester (poly) ol} ester But, but it is not limited to these.
[0032]
Examples of the (poly) epoxide constituting the above-mentioned linking chain or residue (e) include (methyl) epichlorohydrin and epichlorohydrin-modified bisphenol synthesized from bisphenol A or bisphenol F and its ethylene oxide or propylene oxide modified products. Epichlorohydrin-modified hydrogenated bisphenol type epoxy resin, epoxy novolak resin synthesized from (methyl) epichlorohydrin and hydrogenated bisphenol A, hydrogenated bisphenol F, their ethylene oxide modified products, propylene oxide modified products, etc. Reaction products of phenol, biphenol, etc. with (methyl) epichlorohydrin; aromatic epoxy resins such as glycidyl esters of terephthalic acid, isophthalic acid or pyromellitic acid; (poly) Glycols such as tylene glycol, (poly) propylene glycol, (poly) butylene glycol, (poly) tetramethylene glycol, neopentyl glycol, and the like, and polyglycidyl ethers of alkylene oxide modified products thereof; trimethylolpropane, trimethylolethane, and glycerin Glycidyl ether of aliphatic polyhydric alcohols such as diglycerin, diglycerin, erythritol, pentaerythritol, sorbitol, 1,4-butanediol, 1,6-hexanediol, and their alkylene oxide modified products; adipic acid, sebacic acid, maleic acid Glycidyl esters of carboxylic acids such as acids and itaconic acids; glycidyl ethers of polyester polyols of polyhydric alcohols and polycarboxylic acids; glycidyl (meth) acrylate and methyl Glycidyl (meth) acrylate copolymers; glycidyl esters of higher fatty acids, epoxidized linseed oil, epoxidized soybean oil, epoxidized castor oil, aliphatic epoxy resins such as epoxidized polybutadiene, and the like, but are not limited thereto. .
[0033]
Examples of the (poly) ether (poly) isocyanate constituting the linking chain or residue (f) include fatty acids such as methylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tetramethylene diisocyanate, lysine diisocyanate, and dimer acid diisocyanate. Group diisocyanate compound; 2,4-tolylene diisocyanate, dimer of 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, p-xylene diisocyanate, m-xylene diisocyanate, 4,4′-diphenylmethane diisocyanate, Aromatic diisocyanate compounds such as 1,5-naphthylene diisocyanate and 3,3′-dimethylbiphenyl-4,4′-diisocyanate; Polyisocyanates such as cyanates, alicyclic diisocyanates such as 4,4'-methylenebis (cyclohexylisocyanate), methylcyclohexane-2,4 (or 2,6) diisocyanate, and 1,3- (isocyanatomethylene) cyclohexane; Examples include (poly) ether (poly) isocyanate obtained by a urethanization reaction with (poly) ether (poly) ol, but are not limited thereto.
[0034]
Examples of the (poly) ether (poly) ol used in the reaction with the polyisocyanate include polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polybutylene glycol, and polytetramethylene glycol; ethylene glycol, propanediol, propylene glycol, Alkylene glycols such as tetramethylene glycol, pentamethylene glycol, hexanediol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, diglycerin, ditrimethylolpropane, dipentaerythritol, ethylene oxide-modified products, propylene oxide-modified products, Modified butylene oxide, tetrahydrofuran, and the like. Various modified products of Lumpur are preferred.
[0035]
Further, the (poly) ether (poly) ol used for the reaction with the polyisocyanate includes a copolymer of ethylene oxide and propylene oxide, a copolymer of propylene glycol and tetrahydrofuran, a copolymer of ethylene glycol and tetrahydrofuran, and a polyisoprene glycol. Hydrocarbon-based polyols such as hydrogenated polyisoprene glycol, polybutadiene glycol, and hydrogenated polybutadiene glycol; and polyhydric hydroxyl compounds such as polytetramethylene hexaglyceryl ether (tetrahydrofuran-modified hexaglycerin). It is not limited to.
[0036]
Examples of the (poly) ester (poly) isocyanate constituting the linking chain or the residue (g) include, for example, urethanization of the polyisocyanate listed in the linking chain (a) with the (poly) ester (poly) ol. (Poly) ester (poly) isocyanate, etc. obtained by the method described above, but is not limited thereto.
[0037]
Examples of the (poly) ester (poly) ol used in the reaction with the polyisocyanate include ethylene glycol, propanediol, propylene glycol, tetramethylene glycol, pentamethylene glycol, hexanediol, neopentyl glycol, glycerin, trimethylolpropane, Modified ε-caprolactone, γ-butyrolactone, δ-valerolactone, methylvalerolactone, alkylene glycols such as pentaerythritol, diglycerin, ditrimethylolpropane, and dipentaerythritol; adipic acid and dimer acid Aliphatic polyester polyol which is an esterified product of an aliphatic dicarboxylic acid such as a diol and a polyol such as neopentyl glycol or methylpentanediol; Polyester polyols such as aromatic polyester polyols which are esterified products of aromatic dicarboxylic acids such as the above and polyols such as neopentyl glycol; polycarbonate polyols, acrylic polyols, polytetramethylene hexaglyceryl ether (tetrahydrofuran-modified hexaglycerin). Esterified product of a polyvalent hydroxyl group compound such as fumaric acid, phthalic acid, isophthalic acid, itaconic acid, adipic acid, sebacic acid, maleic acid; a polyvalent hydroxyl group compound such as glycerin and an animal or plant fatty acid Examples include, but are not limited to, polyhydric hydroxyl group-containing compounds such as monoglycerides obtained by transesterification with esters.
[0038]
Examples of the (poly) ether (poly) ol constituting the linking chain or the residue (h) include, but are not limited to, the (poly) ether (poly) ol described in the above (a).
[0039]
Examples of the compound used for carbonation with (poly) ether (poly) ol include diethyl carbonate, dipropyl carbonate, and phosgene. The polycarbonate can also be formed by alternate polymerization of epoxide and carbon dioxide, but is not limited thereto.
[0040]
Among these, R₂Is selected from the group consisting of (1) a C2-24 straight-chain alkylene group, a C2-24 branched alkylene group, a C2-24 alkylene group having a hydroxyl group, a cycloalkylene group, an aryl group and an arylalkylene group. (A) (poly) ether-linked chain having an average molecular weight of 100 to 100,000 in which at least one organic group selected is connected by at least one bond selected from the group consisting of (a) an ether bond and (b) an ester bond. Or a (poly) ether residue, or (B) a (poly) ester connecting chain or a (poly) ester residue, among which (2) a straight-chain alkylene group having 2 to 24 carbon atoms, Having an average molecular weight of 100 to 1 comprising a repeating unit containing a branched alkylene group, an alkylene group having 2 to 24 carbon atoms having a hydroxyl group and / or an aryl group. A (poly) ether-linked chain or a (poly) ether residue of 000, or (3) a linear alkylene group having 2 to 24 carbon atoms, a branched alkylene group having 2 to 24 carbon atoms, or a carbon atom having 2 carbon atoms having a hydroxyl group. (Poly) ester connecting chains or (poly) ester residues having an average molecular weight of 100 to 100,000 and consisting of a repeating unit containing ア ル キ レ ン 24 alkylene groups and / or aryl groups are preferred.
[0041]
In recent years, active energy ray-curable compositions, particularly in the field of ultraviolet curable compositions, have been required to have rapid curability. For that purpose, R₁₁And R₁₂Is each independently an alkylene group having 1 to 5 carbon atoms;₁And G₂Each independently represents an ester bond represented by -COO- or -OCO-;₂Has an average molecular weight of 100 to 100, which is a repeating unit containing a linear alkylene group having 2 to 6 carbon atoms, a branched alkylene group having 2 to 6 carbon atoms and / or an alkylene group having 2 to 6 carbon atoms having a hydroxyl group. It is particularly recommended to use a maleimide compound (derivative) that is 1,000 (poly) ether linked chains or (poly) ether residues.
[0042]
The maleimide compound represented by the general formula (A) can be synthesized, for example, by using a known technique as introduced in JP-A-2000-212249.
[0043]
The ink according to the present invention may contain a photoacid generator and a cationically polymerizable monomer in addition to the maleimide compound. This is preferable since it has the effects of increasing the curing speed and suppressing shrinkage during curing.
[0044]
First, the photoacid generator will be described. As the photoacid generator, for example, a compound used for a chemically amplified photoresist or a photocationic polymerization is used (Organic Materials Research Group, edited by "Organic Materials for Imaging", Bunshin Publishing (1993), 187- 192). Examples of compounds suitable for the present invention are given below.
[0045]
First, B (C) of an aromatic onium compound such as diazonium, ammonium, iodonium, sulfonium, and phosphonium is used.₆F₅)₄ ⁻, PF₆ ⁻, AsF₆ ⁻, SbF₆ ⁻, CF₃SO₃ ⁻Salts can be mentioned.
[0046]
Specific examples of the onium compound that can be used in the present invention are shown below.
[0047]
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[0048]
Secondly, sulfonated compounds that generate sulfonic acid can be given, and specific compounds thereof are exemplified below.
[0049]
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[0050]
Third, a halide capable of generating hydrogen halide light can be used, and specific compounds thereof are shown below.
[0051]
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[0052]
Fourth, an iron allene complex can be given.
[0053]
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[0054]
Next, the photopolymerizable compound used in the present invention will be described.
As the cation polymerizable monomer, various known cation polymerizable monomers can be used. For example, epoxy compounds, vinyl ether compounds, and oxetanes exemplified in JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, and JP-A-2001-220526. And the like.
[0055]
Preferred as aromatic epoxides are di- or polyglycidyl ethers prepared by reacting a polyhydric phenol having at least one aromatic nucleus or an alkylene oxide adduct thereof with epichlorohydrin, such as bisphenol A or its alkylene oxide. Examples of the adduct include di- or polyglycidyl ether of an adduct, di- or polyglycidyl ether of a hydrogenated bisphenol A or an alkylene oxide adduct thereof, and a novolak-type epoxy resin. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.
[0056]
As the alicyclic epoxide, cyclohexene oxide obtained by epoxidizing a compound having a cycloalkane ring such as at least one cyclohexene or cyclopentene ring with a suitable oxidizing agent such as hydrogen peroxide or peracid is used. Or a compound containing cyclopentene oxide is preferred.
[0057]
Preferred examples of the aliphatic epoxide include di- or polyglycidyl ethers of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof, and typical examples thereof are diglycidyl ether of ethylene glycol, diglycidyl ether of propylene glycol or Diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, polyglycidyl ether of polyhydric alcohol such as di- or triglycidyl ether of glycerin or an alkylene oxide adduct thereof, polyethylene glycol or alkylene oxide adduct thereof Diglycidyl ether, polypropylene glycol or diglycidyl ether of its alkylene oxide adduct, etc. Ether and the like. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.
[0058]
Among these epoxides, an aromatic epoxide and an alicyclic epoxide are preferable, and an alicyclic epoxide is particularly preferable, in consideration of the rapid curing property. In the present invention, one of the above epoxides may be used alone, or two or more may be used in appropriate combination.
[0059]
Examples of the vinyl ether compound include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexane dimethanol divinyl ether, and Di- or trivinyl ether compounds such as methylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl ether, n- B pills vinyl ether, isopropyl vinyl ether, isopropenyl ether -O- propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.
[0060]
Among these vinyl ether compounds, di- or trivinyl ether compounds are preferable, and divinyl ether compounds are particularly preferable in consideration of curability, adhesion, and surface hardness. In the present invention, one of the above vinyl ether compounds may be used alone, or two or more thereof may be used in an appropriate combination.
[0061]
In the present invention, it is preferable to contain at least one oxetane compound as a photopolymerizable compound for the purpose of suppressing shrinkage of the recording material upon curing of the ink.
[0062]
The oxetane compound is a compound having an oxetane ring, and any known oxetane compound as disclosed in JP-A-2001-220526 and JP-A-2001-310937 can be used.
[0063]
When a compound having five or more oxetane rings is used, the viscosity of the ink composition becomes high, which makes the ink composition difficult to handle, and the glass transition temperature of the ink composition becomes high. It will not be enough. The compound having an oxetane ring is preferably a compound having 1 to 4 oxetane rings.
[0064]
Hereinafter, specific examples of the compound having an oxetane ring will be described, but the present invention is not limited thereto.
[0065]
As an example of the compound having one oxetane ring, a compound represented by the following general formula (1) can be given.
[0066]
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[0067]
In the general formula (1), R¹Is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group or a butyl group, a fluoroalkyl group having 1 to 6 carbon atoms, an allyl group, an aryl group, a furyl group or a thienyl group. R²Is an alkyl group having 1 to 6 carbon atoms such as a methyl group, an ethyl group, a propyl group, a butyl group, a 1-propenyl group, a 2-propenyl group, a 2-methyl-1-propenyl group, a 2-methyl-2- Aromatic rings such as alkenyl groups having 2 to 6 carbon atoms such as propenyl group, 1-butenyl group, 2-butenyl group and 3-butenyl group, phenyl group, benzyl group, fluorobenzyl group, methoxybenzyl group and phenoxyethyl group A group having 2 to 6 carbon atoms such as an alkylcarbonyl group having 2 to 6 carbon atoms such as an ethylcarbonyl group, a propylcarbonyl group and a butylcarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group and a butoxycarbonyl group; Group, ethylcarbamoyl group, propylcarbamoyl group, butylcarbamoyl group, pentylcarbamoyl group, etc. Of 2-6 carbon atoms which is N- alkylcarbamoyl group. As the oxetane compound used in the present invention, it is particularly preferable to use a compound having one oxetane ring, since the resulting composition has excellent tackiness, low viscosity and excellent workability.
[0068]
Examples of the compound having two oxetane rings include a compound represented by the following general formula (2).
[0069]
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[0070]
In the general formula (2), R¹Is a group similar to that in the general formula (1). R³Is, for example, a linear or branched alkylene group such as an ethylene group, a propylene group or a butylene group, or a linear or branched poly (alkyleneoxy) group such as a poly (ethyleneoxy) group or a poly (propyleneoxy) group. Linear or branched unsaturated hydrocarbon groups such as propenylene group, methylpropenylene group, butenylene group, or alkylene group containing carbonyl group or carbonyl group, alkylene group containing carboxyl group, alkylene group containing carbamoyl group, etc. It is.
[0071]
Also, R³Examples thereof include polyvalent groups selected from groups represented by the following general formulas (3), (4) and (5).
[0072]
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[0073]
In the general formula (3), R⁴Is an alkyl group having 1 to 4 carbon atoms such as a hydrogen atom, a methyl group, an ethyl group, a propyl group, and a butyl group; an alkoxy group having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. , A nitro group, a cyano group, a mercapto group, a lower alkoxycarbonyl group, a carboxyl group, or a carbamoyl group.
[0074]
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[0075]
In the general formula (4), R⁵Represents an oxygen atom, a sulfur atom, a methylene group, -NH-, -SO-, -SO₂-, -C (CF₃)₂-Or -C (CH₃)₂Represents-.
[0076]
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[0077]
In the general formula (5), R⁶Is an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, and a butyl group, or an aryl group. n represents the number of 0-2000. R⁷Is an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, and a butyl group, or an aryl group. R⁷Examples further include groups selected from groups represented by the following general formula (6).
[0078]
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[0079]
In the general formula (6), R⁸Is an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, and a butyl group, or an aryl group. m represents the number of 0-100.
[0080]
Specific examples of the compound having two oxetane rings include the following compounds.
[0081]
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[0082]
Exemplified compound 1 is a compound represented by the general formula (2)¹Is an ethyl group, R³Is a carbonyl group. In addition, Exemplified Compound 2 is a compound represented by the general formula (2)¹Is an ethyl group, R³Is R in the general formula (5).⁶And R⁷Is a methyl group and n is 1.
[0083]
Among the compounds having two oxetane rings, preferred examples other than the above compounds include compounds represented by the following general formula (7). In the general formula (7), R¹Is the R of the above general formula (1)¹Is synonymous with
[0084]
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[0085]
In addition, as an example of the compound having 3 to 4 oxetane rings, a compound represented by the following general formula (8) can be given.
[0086]
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[0087]
In the general formula (8), R¹Is R in the general formula (1).¹Is synonymous with R⁹Examples thereof include a branched alkylene group having 1 to 12 carbon atoms such as a group represented by the following A to C, a branched poly (alkyleneoxy) group such as a group represented by the following D, or the following E: And a branched polysiloxy group such as a group. j is 3 or 4.
[0088]
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[0089]
In the above A, R¹⁰Is a lower alkyl group such as a methyl group, an ethyl group or a propyl group. In the above D, p is an integer of 1 to 10.
[0090]
Among the compounds having 3 to 4 oxetane rings, for example, the compound having 4 oxetane rings is exemplified compound 3.
[0091]
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[0092]
Further, examples of the compound having 1 to 4 oxetane rings other than those described above include a compound represented by the following general formula (9).
[0093]
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[0094]
In the general formula (9), R⁸Is R in the above general formula (6)⁸Is synonymous with R¹¹Is an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group or a butyl group or a trialkylsilyl group, and r is 1 to 4.
[0095]
Preferred specific examples of the oxetane compound used in the present invention include the following compounds.
[0096]
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[0097]
The method for producing each compound having an oxetane ring described above is not particularly limited, and may be in accordance with a conventionally known method. For example, Pattisson (DB Pattison, J. Am. Chem. Soc., 3455, 79) (1957)) discloses an oxetane ring synthesis method from a diol. In addition to these, compounds having 1 to 4 oxetane rings having a high molecular weight of about 1,000 to 5,000 are also exemplified. Specific examples of these compounds include the following compounds.
[0098]
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[0099]
Further, the ink according to the present invention may contain a photoradical generator and a radical polymerizable monomer in addition to the maleimide compound. This is preferable since it has the effects of increasing the curing speed and increasing the adhesion of the ink film to the recording material.
[0100]
Conventionally known photoradical generators include arylalkyl ketones, oxime ketones, acyl phosphine oxides, acyl phosphonates, S-phenyl thiobenzoate, titanocene, aromatic ketones, thioxanthones, benzyl and quinone derivatives or ketocoumarins. Can be used.
[0101]
Among them, acyl phosphine oxides and acyl phosphonates are particularly effective for internal curing in ink images having a thickness of 5 to 15 μm per color as in the ink jet method, because the sensitivity is high and the absorption is reduced by photocleavage of the initiator. is there.
[0102]
Specifically, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide and the like are preferable.
[0103]
In addition, in consideration of high sensitivity, safety and odor, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 are preferably used.
[0104]
In the combination considering oxygen polymerization inhibition and sensitivity, a combination of 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 and 1-hydroxy-cyclohexyl-phenyl-ketone, 1-hydroxy- Combination of cyclohexyl-phenyl-ketone and benzophenone, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one or 2-methyl-1 [4- (methylthio) phenyl]- A combination of 2-morpholinopropan-1-one with diethylthioxanthone or isopropylthioxanthone, a combination of benzophenone with an acrylic acid derivative having a tertiary amino group, and the addition of a tertiary amine are effective.
[0105]
Various (meth) acrylate monomers can be used as the radical polymerizable monomer. For example, isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, isomyristyl acrylate, isostearyl acrylate, 2-ethylhexyl-diglycol acrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethyl hexahydrophthalic acid, Butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, -Hydroxy-3-phenoxypropyl acrylate, 2-acryloyloxyethyl succinic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl-2-hydroxyethyl-phthalic acid, lactone-modified flexible acrylate, t-butylcyclohexyl Monofunctional monomers such as acrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexanediol Diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, dimethylol-tricyclodecane diacrylate Diacrylate, EO adduct diacrylate of bisphenol A, PO adduct diacrylate of bisphenol A, neopentyl glycol diacrylate hydroxypivalate, polytetramethylene glycol diacrylate, etc., trimethylolpropane triacrylate, EO modified Trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin propoxy triacrylate, caprolactone-modified trimethylolpropane triacrylate, pentaerythritol ethoxy tetraacrylate, caprolactam-modified diacrylate Pentaerythritol hexaacrelay And trifunctional or higher polyfunctional monomers such as
[0106]
In order to suppress the curing shrinkage upon irradiation with actinic rays, it is preferable to use a monomer having a curing shrinkage of 10% or less. Above all, the monofunctional monomer is preferably used because it has a low shrinkage ratio as compared with a difunctional or higher functional monomer and has flexibility in the ink image, thereby suppressing curling and obtaining adhesion to the recording material. .
[0107]
In addition, from the viewpoint of safety such as sensitization, skin irritation, eye irritation, mutagenicity, toxicity, etc., among the above monomers, particularly, isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, isomil Still acrylate, isostearyl acrylate, ethoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, isobornyl acrylate, lactone-modified flexible acrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, EO Modified trimethylolpropane triacrylate, dipentaerythritol hexaacrylate, dito Trimethylolpropane tetraacrylate, glycerol propoxy triacrylate, caprolactone modified trimethylolpropane triacrylate, pentaerythritol tetraacrylate, caprolactam modified dipentaerythritol hexaacrylate preferred.
[0108]
Further, among them, stearyl acrylate, lauryl acrylate, isostearyl acrylate, ethoxydiethylene glycol acrylate, isobornyl acrylate, tetraethylene glycol diacrylate, EO-modified trimethylolpropane triacrylate, glycerin propoxy triacrylate, cowprolactone-modified trimethylolpropane triacrylate Acrylate, caprolactam-modified dipentaerythritol hexaacrylate is particularly preferred.
When coloring the ink composition according to the present invention, a coloring material is added. As the coloring material, various coloring materials that can be dissolved or dispersed in the main component of the polymerizable compound can be used, and a pigment is preferable from the viewpoint of weather resistance.
[0109]
Pigments that can be preferably used in the present invention are listed below.
C. I \ Pigment \ Yellow-1, 3, 12, 13, 14, 17, 81, 83, 87, 95, 109, 42,
C. I Pigment Orange-16, 36, 38,
C. Pigment Red-5, 22, 38, 48: 1, 48: 2, 48: 4, 49: 1, 53: 1, 57: 1, 63: 1, 144, 146, 185, 101,
C. I Pigment Violet-19, 23,
C. I \ Pigment \ Blue-15: 1, 15: 3, 15: 4, 18, 60, 27, 29,
C. I Pigment Green-7, 36,
C. I \ Pigment \ White-6, 18, 21,
C. I Pigment Black-7
(White ink)
Further, in the present invention, it is preferable to use a white ink in order to improve the color concealing property on a transparent substrate such as a plastic film. In particular, in soft packaging printing and label printing, it is preferable to use white ink, but since the ejection amount increases, the ejection stability described above, from the viewpoint of the occurrence of curling and wrinkling of the recording material, the use amount is naturally determined. There is a limit.
[0110]
For dispersion of the pigment, for example, a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, a paint shaker, and the like can be used. In dispersing the pigment, a dispersant may be added. As the dispersant, a polymer dispersant is preferably used, and as the polymer dispersant, Solsperse series of Avecia is mentioned. In addition, as a dispersing aid, a synergist corresponding to various pigments can be used. These dispersants and dispersing aids are preferably added in an amount of 1 to 50% by mass based on 100% by mass of the pigment. The dispersion medium is performed using a solvent or a polymerizable compound. However, in the radiation-curable ink used in the present invention, it is preferable to use no solvent in order to react and cure immediately after the ink lands. If the solvent remains in the cured image, problems such as deterioration of solvent resistance and VOC (Volatile Organic Compound) of the remaining solvent occur. Therefore, it is preferable from the viewpoint of dispersibility that the dispersion medium is not a solvent but a polymerizable compound, and among them, a monomer having the lowest viscosity is selected.
[0111]
The pigment is dispersed preferably such that the average particle size of the pigment particles is 0.08 μm to 0.5 μm, and the maximum particle size is 0.3 μm to 10 μm, preferably 0.3 μm to 3 μm. The selection of the dispersion medium, dispersion conditions, and filtration conditions are appropriately set. By controlling the particle size, clogging of the head nozzle can be suppressed, and the storage stability of the ink, the transparency of the ink, and the curing sensitivity can be maintained.
[0112]
In the ink according to the present invention, the colorant concentration is preferably 1% by mass to 10% by mass of the whole ink.
[0113]
Various additives other than those described above can be used in the ink according to the present invention. For example, a polymerization inhibitor can be added in an amount of 200 to 20,000 ppm in order to enhance the storage stability of the ink composition. Since it is preferable that the ultraviolet curable ink is heated and reduced in viscosity before ejection, it is preferable to add a polymerization inhibitor in order to prevent head clogging due to thermal polymerization. In addition, if necessary, surfactants, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins, rubber resins, waxes, etc. Can be added. It is also effective to add a trace amount of an organic solvent in order to improve the adhesion to the recording medium. In this case, the addition is effective within a range in which the problem of solvent resistance and VOC does not occur, and the amount used is in the range of 0.1 to 5%, preferably 0.1 to 3%. It is also possible to combine a radical polymerizable monomer and an initiator to obtain a radical-cation hybrid cured ink.
[0114]
《Image forming method》
The image forming method of the present invention will be described.
[0115]
In the image forming method of the present invention, a method in which the above ink composition is ejected onto a recording material by an ink jet recording method to draw an image, and then the ink is cured by irradiation with actinic rays such as ultraviolet rays is preferable.
[0116]
(Total ink film thickness after ink landing)
In the present invention, it is preferable that the total ink film thickness after the ink lands on the recording material and is cured by irradiation with actinic rays is 2 μm to 20 μm. In the actinic ray-curable inkjet recording in the screen printing field, the total ink film thickness currently exceeds 20 μm. However, in the flexible packaging printing field where the recording material is often a thin plastic material, the recording material described above is used. In addition to the problem of curl and wrinkles, there is a problem that the stiffness and texture of the entire printed matter is changed.
[0117]
Here, the “total ink film thickness” means the maximum value of the film thickness of the ink drawn on the recording material. The same applies to the meaning of the total ink film thickness even when recording is performed by the superposition (white ink base) ink jet recording method.
[0118]
(Ink ejection conditions)
It is preferable that the recording head and the ink are heated to 35 ° C. to 100 ° C. and ejected from the viewpoint of ejection stability. Actinic ray-curable inks have large fluctuations in viscosity due to temperature fluctuations.Viscosity fluctuations directly affect the droplet size and droplet ejection speed and degrade image quality. It is necessary to keep. The control range of the ink temperature is set temperature ± 5 ° C., preferably set temperature ± 2 ° C., and more preferably set temperature ± 1 ° C.
[0119]
In the present invention, it is preferable that the amount of liquid droplets ejected from each nozzle is 2 pl to 15 pl.
[0120]
Originally, in order to form a high-definition image, the droplet amount needs to be within this range. However, when the droplet amount is discharged, the above-described discharge stability becomes particularly severe. According to the present invention, the ejection stability is improved even if the ink is ejected with a small droplet amount such as 2 pl to 15 pl, and a high-definition image can be stably formed.
[0121]
(Light irradiation conditions after ink landing)
In the image recording method of the present invention, as the irradiation condition of the actinic ray, it is preferable that the actinic ray is irradiated during 0.001 seconds to 2.0 seconds after the ink has landed, more preferably 0.001 seconds to 1 second. 0.0 seconds. In order to form a high-definition image, it is particularly important that the irradiation timing is as early as possible.
[0122]
A basic method of irradiating actinic rays is disclosed in JP-A-60-132767. According to this, light sources are provided on both sides of the head unit, and the head and the light source are scanned in a shuttle system. Irradiation is performed at a fixed time after the ink has landed. Further, the curing is completed by another light source without driving. U.S. Patent No. 6,145,979 discloses a method using an optical fiber or a method in which a collimated light source is applied to a mirror provided on a side surface of a head unit to irradiate a recording unit with UV light. I have. In the image forming method of the present invention, any of these irradiation methods can be used.
[0123]
The irradiation of the actinic ray is divided into two stages. First, the actinic ray is irradiated by the above-described method for 0.001 to 2.0 seconds after the ink has landed, and the actinic ray is further irradiated after the completion of all printing. The method is also one of the preferred embodiments. By dividing the irradiation of the actinic ray into two stages, it is possible to further suppress the contraction of the recording material that occurs when the ink is cured.
[0124]
Conventionally, in the UV inkjet system, a high-illuminance light source whose total power consumption exceeds 1 kW · hr has been generally used to suppress dot spread and bleeding after ink landing. However, when these light sources are used, especially in printing on a shrink label or the like, at present, the recording material shrinks so much that it cannot be practically used.
[0125]
In the present invention, a high-definition image can be formed even with a light source having a total power consumption of 1 kW · hr or more by using an active light beam having the highest illuminance in a wavelength range of 280 nm to 320 nm, and a recording material can be formed. Shrinkage is also within practically acceptable levels.
[0126]
In the present invention, it is preferable that the total power consumption of the light source for irradiating the active ray is less than 1 kW · hr. Examples of the light source having a total power consumption of less than 1 kW · hr include, but are not limited to, a fluorescent tube, a cold cathode tube, and an LED.
[0127]
<< printed matter >>
The printed matter of the present invention will be described.
[0128]
The printed matter of the present invention is characterized in that it is produced on a non-absorbable recording material by using the image forming method of the present invention and / or the image forming apparatus of the present invention. Here, non-absorptive means that the ink composition (also simply referred to as ink) is not absorbed. In the present invention, the ink transfer amount in the Bristow method as described below is 0.1 ml / mm.²Less than 0 ml / mm²Is defined as a non-absorbable recording material.
[0129]
《Bristow method》
The Bristow method in the present invention is a method for measuring the liquid absorption behavior of paper and paperboard in a short time. TAPPI paper pulp test method No. 51-87 Measured according to the liquid absorption test method of paper or paperboard (Bristow method), and measured the ink transfer amount (ml / m2) at a contact time of 40 ms.²). In the above measurement method, pure water (ion-exchanged water) is used for the measurement. However, in order to facilitate determination of the measurement area, the present invention contains less than 2% of a water-soluble dye. You may.
[0130]
An example of a specific measurement method will be described below.
As a method of measuring the amount of ink transfer, a recording medium is allowed to stand in an atmosphere of 25 ° C. and 50% RH for 12 hours or more, and then, for example, a Bristow test, which is a liquid dynamic absorption tester manufactured by Kumagaya Riki Kogyo Co., Ltd. It is measured using a model II (pressurized type). The liquid used for the measurement is a commercially available water-based inkjet ink (for example, magenta ink) in order to improve the measurement accuracy, and the ink transfer amount is measured by measuring the area of the magenta-stained portion on the recording medium after a specified contact time. Can be requested.
[0131]
(Non-absorbable recording material)
As the non-absorbable recording material according to the present invention, in addition to ordinary non-coated paper, coated paper, etc., various non-absorbable plastics and films thereof used for so-called flexible packaging can be used. For example, a PET film, an OPS film, an OPP film, an ONy film, a PVC film, a PE film, and a TAC film can be mentioned. As other plastics, polycarbonate, acrylic resin, ABS, polyacetal, PVA, rubbers and the like can be used. Further, the present invention can be applied to metals and glasses. Among these recording materials, the structure of the present invention is particularly effective when an image is formed on a PET film, an OPS film, an OPP film, an ONy film, or a PVC film which can be shrunk by heat. These base materials not only tend to curl and deform the film due to the curing shrinkage of the ink and the heat generated during the curing reaction, but also make it difficult for the ink film to follow the shrinkage of the base material.
[0132]
These various plastic films have greatly different surface energies, and there has conventionally been a problem that the dot diameter after ink landing varies depending on the recording material. In the configuration of the present invention, the surface energy is 0.035 J / m including OPP film and OPS film having low surface energy and PET having relatively high surface energy.²~ 0.06 J / m²Although a good high-definition image can be formed on a wide range of recording materials as described above, the effect described in the present invention is more preferably obtained at 0.040 J / m²~ 0.06 J / m²Recording material in the range.
[0133]
In the present invention, it is more advantageous to use a long (web) recording material in terms of the cost of the recording material such as packaging cost and production cost, the print production efficiency, and the ability to cope with prints of various sizes. is there.
[0134]
BEST MODE FOR CARRYING OUT THE INVENTION
《Recording device》
The recording apparatus of the present invention will be described.
[0135]
Hereinafter, the recording apparatus of the present invention will be described with reference to the drawings as appropriate. Note that the recording device shown in the drawings is merely an embodiment of the recording device of the present invention, and the recording device of the present invention is not limited to the drawings.
[0136]
FIG. 1 is a front view showing the configuration of the main part of the recording apparatus of the present invention. The recording apparatus 1 includes a head carriage 2, a recording head 3, an irradiation unit 4, a platen unit 5, and the like. In the recording apparatus 1, a platen unit 5 is provided below a recording material P. The platen unit 5 has a function of absorbing ultraviolet rays, and absorbs extra ultraviolet rays that have passed through the recording material P. As a result, a high-definition image can be reproduced very stably.
[0137]
The recording material P is guided by the guide member 6 and moves from the near side to the far side in FIG. 1 by the operation of the conveying means (not shown). The head scanning means (not shown) scans the recording head 3 held by the head carriage 2 by reciprocating the head carriage 2 in the Y direction in FIG.
[0138]
The head carriage 2 is installed on the upper side of the recording material P, and accommodates a plurality of recording heads 3 described below in accordance with the number of colors used for image printing on the recording material P, and arranges and discharges ejection ports on the lower side. The head carriage 2 is mounted on the main body of the recording apparatus 1 so as to be reciprocable in the Y direction in FIG. 1, and reciprocates in the Y direction in FIG. 1 by driving the head scanning unit.
[0139]
In FIG. 1, the head carriage 2 is white (W), yellow (Y), magenta (M), cyan (C), black (K), light yellow (Ly), light magenta (Lm), and light cyan (Lc). , Light black (Lk) and white (W) recording heads 3, but the number of colors of the recording heads 3 stored in the head carriage 2 is appropriately determined at the time of implementation. Things.
[0140]
The recording head 3 discharges an actinic ray curable ink (for example, a UV curable ink) supplied by an ink supply unit (not shown) by the operation of a plurality of ejection units (not shown) provided therein. From the recording material P toward the recording material P. The UV ink ejected by the recording head 3 is composed of a coloring material, a polymerizable monomer, an initiator, and the like, and the monomer is cross-linked due to the initiator acting as a catalyst when irradiated with ultraviolet rays. It has the property of being cured by a polymerization reaction.
[0141]
During a scan in which the recording head 3 moves from one end of the recording material P to the other end of the recording material P in the Y direction in FIG. 1 by driving the head scanning means, a fixed area (landable area) in the recording material P , The UV ink is ejected as ink droplets, and the ink droplets land on the landable area.
[0142]
The above scanning is performed as appropriate, and after the UV ink is ejected toward one of the landable areas, the recording material P is appropriately moved from the near side to the back side in FIG. The recording head 3 discharges UV ink to the next landable area adjacent in the depth direction in FIG. 1 to the landable area.
[0143]
By repeating the above operation and ejecting the UV ink from the recording head 3 in conjunction with the head scanning unit and the conveying unit, an image formed of an aggregate of UV ink droplets is formed on the recording material P.
[0144]
The irradiating means 4 includes an ultraviolet lamp that emits ultraviolet light of a specific wavelength region with stable exposure energy and a filter that transmits ultraviolet light of a specific wavelength. Here, as the ultraviolet lamp, a mercury lamp, a metal halide lamp, an excimer laser, an ultraviolet laser, a cold cathode tube, a black light, an LED (light emitting diode), or the like is applicable. Lamp tubes or black lights are preferred. In particular, a cold-cathode tube and a black light that emit ultraviolet light having a wavelength of 365 nm are preferable because they can prevent bleeding, can efficiently control the dot diameter, and can reduce wrinkles during curing. By using the black light as the radiation source of the irradiation unit 4, the irradiation unit 4 for curing the UV ink can be manufactured at low cost.
[0145]
The irradiating means 4 has the same shape as the largest one that can be set by the recording apparatus (UV inkjet printer) 1 in the landable area where the recording head 3 ejects UV ink by one scan by driving the head scanning means. , And has a shape larger than the landable area.
[0146]
The irradiation means 4 is fixedly installed on both sides of the head carriage 2 substantially parallel to the recording material P.
[0147]
As described above, the means for adjusting the illuminance of the ink ejection unit not only shields the entire recording head 3 from light, but also adjusts the ink ejection of the recording head 3 based on the distance h1 between the irradiation unit 4 and the recording material P. It is effective to increase the distance h2 between the unit 31 and the recording material P (h1 <h2) and increase the distance d between the recording head 3 and the irradiation unit 4 (increase d). Further, it is more preferable that a bellows structure 7 is provided between the recording head 3 and the irradiation means 4.
[0148]
Here, the wavelength of the ultraviolet light irradiated by the irradiation means 4 can be appropriately changed by exchanging an ultraviolet lamp or a filter provided in the irradiation means 4.
[0149]
As the recording material, in addition to ordinary uncoated paper, coated paper, and the like, various non-absorbable plastics and films thereof used in so-called flexible packaging can be used. Examples of various plastic films include PET (polyethylene terephthalate) film, OPS (stretched polystyrene) film, OPP (stretched polypropylene) film, ONy (stretched nylon) film, PVC (polyvinyl chloride) film, PE film, and TAC film. As other plastics, polycarbonate, acrylic resin, ABS, polyacetal, PVA, rubbers and the like can be used. Further, the present invention can be applied to metals and glasses.
[0150]
Among these recording materials, the effect of the present invention is more effective when an image is formed on a PET film, an OPS film, an OPP film, an ONy film, or a PVC film which can be shrunk by heat. These base materials not only tend to curl and deform the film due to the curing shrinkage of the ink and the heat generated during the curing reaction, but also make it difficult for the ink film to follow the shrinkage of the base material.
[0151]
In the present invention, it is more advantageous to use a long (web) recording material in terms of the cost of the recording material such as packaging cost and production cost, the print production efficiency, and the ability to cope with prints of various sizes. is there.
[0152]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.
[0153]
Example 1
<< Preparation of ink composition >>
Ink compositions 1 to 3 having the configurations shown in Tables 1 to 3 were prepared. Table 1 shows the ink composition 1, Table 2 shows the ink composition 2, and Table 3 shows the ink composition 3.
[0154]
[Table 1]

[0155]
[Table 2]

[0156]
[Table 3]

[0157]
Abbreviations of the inks described in Tables 1 to 3 and details of each compound are as follows.
K: dark black ink
C: dark cyan ink
M: Dark magenta ink
Y: dark yellow ink
Lk: Light black ink
Lc: Light cyan ink
Lm: light magenta ink
Ly: pale yellow ink
Coloring material 1: C.I. I. pigment Black 7
Coloring material 2: C.I. I. pigment Blue 15: 3
Coloring material 3: C.I. I. pigment Red 57: 1
Coloring material 4: C.I. I. pigment Yellow 13
Photo-radical polymerizable compound 1: lauryl acrylate (monofunctional)
Photo-radical polymerizable compound 2: bisphenol A glycidyl ether methacrylic acid adduct (bifunctional)
Photo-radical polymerizable compound 3: tetraethylene glycol diacrylate (bifunctional)
Photo-radical polymerizable compound 4: trimethylolpropane triacrylate (trifunctional)
Photo-radical polymerizable compound 5: caprolactam-modified dipentaerythritol hexaacrylate (hexafunctional)
Photo radical generator 1: Irgacure 651 (manufactured by Ciba Specialty Chemicals)
Photoradical generator 2: Irgacure 369 (manufactured by Ciba Specialty Chemicals)
Initiator auxiliary agent: diethylthioxanthone
Maleimide compound 1: (LUMICURE MIA200 manufactured by DIC)
Tertiary amino compound: EPA (ethyl p-dimethylaminobenzoate) (manufactured by Nippon Kayaku)
<< Inkjet image forming method >>
Each of the ink compositions prepared above was loaded into an ink jet recording apparatus equipped with a piezo-type ink jet nozzle as shown in FIG. 1 and had a surface energy as shown in Table 4, a width of 600 mm and a length of 1000 m. The following image recording was continuously performed on each recording material. The ink supply system was composed of an ink tank, a supply pipe, a front chamber ink tank immediately before the head, a pipe with a filter, and a piezo head. The temperature of the piezo head was adjusted to 30 ° C. The piezo head unit was driven to eject multi-size dots of 2 pl to 15 pl at a resolution of 720 dpi × 720 dpi (dpi represents the number of dots per 2.54 cm), and continuously ejected each ink. After landing, a curing treatment was performed 0.2 seconds later under the irradiation conditions shown in Table 4. After recording, when the total ink film thickness was measured, it was in the range of 2.3 μm to 13 μm.
[0158]
[Table 4]

[0159]
(1) Details of the abbreviations of the recording materials described in Table 4 are as follows.
OPP: oriented @ polypropylene
PET: polyethylene @ terephthalate
ONy: oriented @ nylon
PVC: polyvinylchloride
(2) Details of the irradiation light sources described in Table 4 are as follows.
[0160]
Irradiation light source 1: UV lamp without power supply (manufactured by Fusion UV Systems Japan)
(F450 series @ power: 3 kWhr)
Irradiation light source 2: Cold-cathode tube (custom made by Hibeck, Inc. Power: less than 1 kW · hr)
Irradiation light source 3: Fluorescent lamp (Nippo Electric Co., Ltd. custom-made product. Power: less than 1 kW · hr)
(3) Irradiation timing: 0.2 seconds after landing
(4) Irradiation method
Irradiation light source 1: Recording head bilateral and linear light source irradiation
Irradiation light source 2: Irradiate with 10 horizontal light sources on both sides of the recording head
Irradiation light source 3: Irradiate with three horizontal and linear light sources on both sides of the recording head
(5) Maximum illuminance on the recording material surface and its peak wavelength
Irradiation light source 1: 700 mW / cm at 365 nm peak wavelength²
Irradiation light source 2: 15 mW / cm at a peak wavelength of 308 nm²
Irradiation light source 3: 10 mW / cm at a peak wavelength of 310 nm²
(6) Exposure energy and its peak wavelength
Irradiation light source 1: 200 mJ / cm at a peak wavelength of 365 nm²
Irradiation light source 2: 40 mJ / cm at a peak wavelength of 308 nm²
Irradiation light source 3: 30 mJ / cm at a peak wavelength of 310 nm²
<< Evaluation of inkjet recorded image >>
Each of the images recorded by the above image forming method was evaluated as follows. Each evaluation was performed on a 10 m sample, a 100 m sample, and a 500 m sample after printing of continuously ejected image recording. Table 5 shows the obtained evaluation results.
[0161]
《Evaluation of character quality》
6-point MS Mincho characters were printed at the target density for each of the colors Y, M, C, and K, and the roughness of the characters was magnified and observed with a loupe.
[0162]
◎: No roughness
：: slight roughness was observed
Δ: Roughness is recognized, but can be distinguished as characters
×: Severely rough and the letters are faint and cannot be used
<< Evaluation of color mixing (bleeding) >>
Adjacent colors dots in the printed high-definition image were magnified with a loupe and the degree of bleeding was visually observed, and the color mixture was evaluated according to the following criteria.
[0163]
A: Neighboring dot shapes keep a perfect circle and no bleeding
Good: Neighboring dot shapes keep almost perfect circles and almost no bleeding
Δ: The adjacent dots are slightly blurred and the dot shape is slightly distorted, but within an allowable range.
×: Adjacent dots are blurred and mixed, and are at a level that cannot be used.
《Evaluation of wrinkles and curls on printed materials》
After printing at 10 m, 100 m and 500 m, each printed matter was visually observed for wrinkles and curls due to irradiation and curing, and evaluated according to the following evaluation criteria.
[0164]
：: good without wrinkles or curls
Δ: Some wrinkles and curls were observed, but within a practically acceptable range
×: Strong wrinkles and curls are observed in the printed matter, which is a practical problem.
[0165]
[Table 5]

[0166]
From Table 5, it can be seen that the sample of the present invention is excellent in character quality, has no color mixing, can record a high-definition image, and has no wrinkles or curls in the printed matter as compared with the comparison. it is obvious.
[0167]
Example 2
<< Preparation of ink composition >>
Ink compositions 4 to 6 having the configurations shown in Tables 6 to 8 were prepared. Table 6 shows Ink Composition 4, Table 7 shows Ink Composition 5, and Table 8 shows Ink Composition 6.
[0168]
[Table 6]

[0169]
[Table 7]

[0170]
[Table 8]

[0171]
The details of each compound described in Tables 6 to 8 are as follows.
K: dark black ink
C: dark cyan ink
M: Dark magenta ink
Y: dark yellow ink
Lk: Light black ink
Lc: Light cyan ink
Lm: light magenta ink
Ly: pale yellow ink
W: White ink
Coloring material 1: C.I. I. pigment Black 7
Coloring material 2: C.I. I. pigment Blue 15: 3
Coloring material 3: C.I. I. pigment Red 57: 1
Coloring material 4: C.I. I. pigment Yellow 13
Coloring material 5: titanium oxide (anatase type タ ー ゼ average particle size 0.20 μm)
Photocationic polymerizable compound 1 (epoxy compound): Celloxide 3000 (manufactured by Daicel Chemical Industries, Ltd.)
Photocationically polymerizable compound 2 (oxetane compound): OXT-221 (manufactured by Toa Gosei Chemical Co., Ltd.)
Photocationically polymerizable compound 3 (oxetane compound): OXT-212 (manufactured by Toa Gosei Chemical Co., Ltd.)
Photocationically polymerizable compound 4 (oxetane compound): OXT-211 (manufactured by Toa Gosei Chemical Co., Ltd.)
Photocationically polymerizable compound 5 (oxetane compound): DAIMIC @ S300K (manufactured by Daicel Chemical Industries, Ltd.)
Acid Proliferator 1: Compound 1
Acid Proliferator 2: Compound 2
Basic compound 1: N-ethyldiethanolamine
Basic compound 2: tripropylamine
Thermal base generator 1: The following structural formula
Thermal base generator 2: The following structural formula
Photoacid generator 1: CS5102 (manufactured by Nippon Soda Co., Ltd.)
Photoacid generator 2: SP152 (manufactured by Asahi Denka Kogyo)
Initiator assistant: CI7001 (Nippon Soda Co., Ltd.)
[0172]
Embedded image

[0173]
Maleimide compound 2: The following structural formula
[0174]
Embedded image

[0175]
<< Synthesis of Maleimide Compound 2 >>
Step 1: Synthesis of maleimide acetic acid
37.5 g of glycine and 400 ml of acetic acid were charged into a 1-liter three-necked flask equipped with a dropping funnel, a condenser, and a stirrer, and a solution consisting of 49.0 g of maleic anhydride and 300 ml of acetic acid was stirred with stirring at room temperature. The solution was dropped from the dropping funnel over 2 hours. After completion of the dropwise addition, stirring was further continued for 1 hour, and then the reaction was terminated. The resulting precipitate was collected by filtration and recrystallized from a mixed solvent of water: methanol = 3: 7 (volume ratio) to obtain 11 g of maleimide acetic acid.
[0176]
(Physical properties of maleimide acetic acid)
(¹H-NMR measurement): Measurement conditions (300 MHz, DMSO-d6)
7.0 ppm (s, 2H, -C = C-)
4.1 ppm (s, 2H, -CH₂−)
(IR measurement)
3170cm^-1(-COOH)
1750cm^-1, 1719cm^-1(C = O)
831cm^-1, 696cm^-1(-C = C-)
(Elemental analysis): element to be measured (CHN)
Calculated values: C 46.5%, H 3.87%, N 9.03%
Analytical values: C 46.2%, H 4.05%, N 8.70%
Step 2: Maleimide acetic acid synthesis
Subsequently, polytetramethylene glycol having a number average molecular weight of 250 (“Poly (THF250)” manufactured by BSF Japan, Inc.) was placed in a 200 ml eggplant-shaped flask equipped with a Dean-Stark fractionator. GPC value in terms of polystyrene: number average molecular weight 440, weight average molecular weight 470) 5 g, maleimide acetic acid 6.8 g obtained above, p-toluenesulfonic acid 1.2 g, 2,6-tert-butyl-p-cresol 0.1 g. 06 g and 15 ml of toluene were charged, and stirring was continued for 4 hours while removing water generated at 32000 Pa and 80 ° C. to continue the reaction. The reaction mixture was dissolved in 200 ml of toluene, and washed three times with 100 ml of saturated sodium bicarbonate and once with 100 ml of saturated saline. The organic phase was concentrated to obtain 9 g of a pale yellow liquid of a maleimide compound 2 represented by the following formula.
[0177]
(Physical properties of maleimide compound 2)
(IR)
1750cm^-1, 1719cm^-1(C = O)
831cm^-1, 698cm^-1(C = C)
(¹H-NMR): Measurement conditions (300 MHz, CDCl₃)
6.7 ppm (s, 4H, -CH = CH-)
4.3 ppm [s, 4H, N-CH₂-(C = O)-]
4.1 ppm (t, 4H,-(C = O) -O-CH₂−)
3.4 to 3.5 ppm (m, -O-CH₂−)
1.6 to 1.7 ppm (m, -CH₂−)
(¹³C-NMR): Measurement conditions (75 MHz, CDCl₃)
170 ppm [N- (C = O)]
167 ppm [-(C = O) -O]
135 ppm (-CH = CH-)
64.5 to 70.9 ppm (-O-CH₂−)
38.7 ppm (N-CH₂−)
25.7 to 26.6 ppm (-CH₂−)
(Results of molecular weight distribution analysis by GPC (polystyrene conversion))
Number average molecular weight 730, weight average molecular weight 750
<< Inkjet image forming method >>
Each ink composition prepared above was loaded into an ink jet recording apparatus equipped with a piezo type ink jet nozzle as shown in FIG. 1 and had a surface energy of 600 mm in width and 1000 m in length having a surface energy shown in Table 9. The following image recording was continuously performed on each recording material. The ink supply system was composed of an ink tank, a supply pipe, a front chamber ink tank immediately before the head, a pipe with a filter, and a piezo head. The temperature of the piezo head was adjusted to 50 ° C. The piezo head unit was driven so that multi-size dots of 2 pl to 15 pl could be ejected at a resolution of 720 dpi × 720 dpi to continuously eject each ink. 0.15 seconds after the impact, a curing treatment was performed under the irradiation conditions shown in Table 9. After recording, when the total ink film thickness was measured, it was in the range of 2.3 μm to 19.6 μm.
[0178]
[Table 9]

[0179]
(1) Details of the abbreviations of the recording materials described in Table 9 are as follows.
OPP: oriented @ polypropylene
PET: polyethylene @ terephthalate
ONy: oriented @ nylon
Shrink PVC: commercially available polyvinyl chloride for shrink applications
Shrink OPS: Oriented @ polystyrene for commercial shrink applications
(2) Details of the irradiation light sources described in Table 9 are as follows.
[0180]
Irradiation light source 4: Black light (Nippo Electric Co., Ltd. custom-made product. Power: less than 1 kW · hr)
Irradiation light source 5: Cold-cathode tube (custom made by Hibeck Co., Ltd. Power: less than 1 kW · hr)
Irradiation light source 6: LED (special product manufactured by Nichia Corporation; power: less than 1 kW · hr)
(3) Irradiation timing: 0.15 seconds after landing
(4) Irradiation method
Irradiation light source 4: Irradiates with three horizontal and linear light sources on both sides of the recording head
Irradiation light source 5: Irradiate with 10 horizontal light sources on both sides of the recording head
Irradiation light source 6: irradiate with three horizontal and linear light sources on both sides of the recording head
(5) Maximum illuminance on the recording material surface and its peak wavelength
Irradiation light source 4: 10 mW / cm at 365 nm peak wavelength²
Irradiation light source 5: 15 mW / cm at a peak wavelength of 308 nm²
Irradiation light source 6: 10 mW / cm at a peak wavelength of 310 nm²
(6) Exposure energy and its peak wavelength
Irradiation light source 4: 35 mJ / cm at 365 nm peak wavelength²
Irradiation light source 5: 40 mJ / cm at a peak wavelength of 308 nm²
Irradiation light source 6: 30 mJ / cm at a peak wavelength of 310 nm²
<< Evaluation of inkjet recorded image >>
For each of the images recorded by the above image forming method, the character quality, color mixture, and The wrinkles and curls of the printed matter were evaluated, and the results are shown in Table 10.
[0181]
[Table 10]

[0182]
From Table 10, it can be seen that the sample of the present invention is excellent in character quality, has no color mixing, can record a high-definition image, and has no wrinkles or curls of the printed matter as compared with the comparison. it is obvious.
[0183]
【The invention's effect】
According to the present invention, for any recording material, excellent in character quality, no occurrence of color mixing, high-definition images can be recorded, and wrinkles and curling of printed matter, image forming method, printed matter and A recording device could be provided.
[Brief description of the drawings]
FIG. 1 is a front view showing a configuration of a main part of a recording apparatus of the present invention.
[Explanation of symbols]
1 Recording device
2 Head carriage
3 Recording head
4 Irradiation means
5 Platen
6 guide member
7 bellows structure
P recording material

Claims (19)

An image forming method in which an ink curable by actinic light is ejected onto a recording material by a recording head having at least one nozzle capable of selectively controlling ejection of ink droplets, wherein the ink contains a compound containing a maleimide skeleton. And curing the ink using an actinic ray having the highest illuminance in the wavelength range of 280 nm to 320 nm. 2. The image forming method according to claim 1, wherein the actinic light is irradiated for 0.001 to 2.0 seconds after the ink has landed. 3. The image forming method according to claim 1, wherein a total ink film thickness after the ink lands and is cured by irradiation with actinic rays is 2 μm to 20 μm. 4. 4. The image forming method according to claim 1, wherein the amount of ink droplets ejected from each nozzle of the recording head is 2 pl to 15 pl. 5. The image forming method according to claim 1, wherein at least one color of the ink is a white ink. The image forming method according to claim 1, wherein the ink contains at least one photoacid generator and a cationically polymerizable monomer. The image forming method according to claim 1, wherein the ink contains at least one kind of a photoradical generator and a radical polymerizable monomer. The image forming method according to any one of claims 1 to 7, wherein the compound containing a maleimide skeleton is represented by the following general formula (A).

[In the formula, m and n each independently represent an integer of 1 or more. R ₁₁ and R ₁₂ each independently represent a divalent group having an aliphatic group or an aromatic group. G ₁ and G ₂ each independently represent an ether bond, an ester bond, a urethane bond, or a carbonate bond. R ₂ is an average in which an aliphatic group or an aromatic group is connected by at least one bond selected from the group consisting of (a) an ether bond, (b) an ester bond, (c) a urethane bond, and (d) a carbonate bond. (A) (poly) ether-linked chain or (poly) ether residue, (B) (poly) ester-linked chain or (poly) ester residue, (C) (poly) urethane-linked chain having a molecular weight of 40 to 100,000 Or (poly) urethane residue or (D) a (poly) carbonate connecting chain or (poly) carbonate residue. ] A printed matter produced by the image forming method according to claim 1, using a non-absorbable recording material. Printed matter according to claim 9 in which the surface energy of the non-absorbent recording ^material, characterized in that it is a ^{35mJ / m 2 ~60mJ / m 2} . A recording apparatus having at least one nozzle capable of selectively controlling the ejection of ink droplets, which is a recording apparatus that forms an image by ejecting an ink that is hardened by actinic rays onto a recording material. A recording apparatus, comprising: curing an ink using an actinic ray containing a compound having a maleimide skeleton and having maximum illuminance in a wavelength range of 280 nm to 320 nm. 12. The recording apparatus according to claim 11, wherein the recording medium is irradiated with an actinic ray for 0.001 to 2.0 seconds after the ink has landed. The recording apparatus according to claim 11, wherein a total ink film thickness after the ink has landed and is cured by irradiation with actinic rays is 2 μm to 20 μm. 14. The recording apparatus according to claim 11, wherein the amount of ink droplets ejected from each nozzle of the recording head is 2 pl to 15 pl. 15. The recording apparatus according to claim 11, wherein at least one color of the ink is white ink. The recording apparatus according to any one of claims 11 to 15, wherein the ink contains at least one kind of a photoacid generator and a cationically polymerizable monomer. 17. The recording apparatus according to claim 11, wherein the ink contains at least one kind of a photoradical generator and a radical polymerizable monomer. 18. The recording apparatus according to claim 11, wherein the compound containing a maleimide skeleton is represented by the general formula (A). The recording apparatus according to any one of claims 11 to 18, wherein a total power consumption of a light source for irradiating actinic rays is less than 1 kW · hr.

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