JP2004098553A - Ink jet head and ink jet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the erosion resistance to a photo-curing ink, to prevent clogging of ink nozzles and ink leakage even when the ink nozzles are used for a long time, to stably secure also an ink droplet jetting precision and to reduce effects onto an ink sensitivity. <P>SOLUTION: The ink jet head comprises a constituent member whose mass change is in a range of -0.8 to 8.0mass% when the ink jet head is subjected to an ink immersion test. <P>COPYRIGHT: (C)2004,JPO

Description

【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、得られるインクが粘着性に優れ、低粘度で作業性に優れるため、特に好ましく用いられる。
【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２】

【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】
又、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３】

【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４】

【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５】

【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の整数である。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６】

【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の整数である。
【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７】

【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がカルボキシル基である化合物である。又、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８】

【００８５】
又、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９】

【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１０】

【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。又、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一例としては、例示化合物３が挙げられる。
【００９１】
【化１１】

【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１２】

【００９４】
一般式（９）において、Ｒ^８は前記一般式（１９）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】
本発明に係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１３】

【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。又、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１４】

【００９９】
《非プロトン性極性溶媒》
本発明に係る非プロトン性極性溶媒について説明する。
【０１００】
非プロトン性極性溶媒としては、ジメチルイミダゾリジノン、Ｎ−メチルピロリドン（ＮＭＰ）、Ｎ，Ｎ−ジメチルホルムアミド（ＤＭＦ）、Ｎ，Ｎ−ジメチルアセトアミド（ＤＭＡｃ）、ジメチルスルホキシド（ＤＭＳＯ）、スルホラン、２，４−ジメチルスルホラン、スルホレン、キノリン、イソキノリン、２，６−ルチジン、２，４，６−トリメチルピリジン、テトラメチル尿素、ジオキサン、テトラヒドロフラン（ＴＨＦ）、ヘキサメチルホスホリックトリアミド（ＨＭＰＡ）、Ｎ−メチルモルホリン（ＮＭｍ）、γ−ブチロラクトン（ＢＬｏ）、ニトロメタン、ニトリル基を有する化合物等が挙げられる。
【０１０１】
中でも、上記のニトリル基を有する化合物が特に好ましく用いられる。ニトリル基を有する化合物としては、例えば、アセトニトリル（ＡｃＮ）、ブチロニトリル、アクリロニトリル等が挙げられる。
【０１０２】
（非プロトン性極性溶媒の使用量）
非プロトン性極性溶媒の使用量は、本発明に記載の効果を好ましく発現し、且つ、色濁り等の防止する観点から、インク全量１００質量部に対して、０質量部〜２０質量部の範囲が好ましく、更に好ましくは、０質量部〜１０質量部であり、特に好ましくは０質量部〜５質量部である。
【０１０３】
《ラジカル重合性モノマー》
本発明に係る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−アクリロイロ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−アクリロイキシエチルコハク酸、２−アクリロイキシエチルフタル酸、２−アクリロイキシエチル−２−ヒドロキシエチル−フタル酸、ラクトン変性可とう性アクリレート、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等の三官能以上の多官能モノマーが挙げられる。
【０１０４】
尚、光（活性光線ともいう）照射したときのインク面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られるので好ましく用いることが出来る。
【０１０５】
本発明に係るラジカル重合性モノマーのインク中における好ましい含有量は、１０質量％〜５０質量％の範囲が好ましく、更に好ましくは、１０質量％〜３０質量％の範囲である。
【０１０６】
《光酸発生剤》
本発明に用いられる光酸発生剤について説明する。
【０１０７】
光酸発生剤としては、例えば、化学増幅型フォトレジストや光カチオン重合に利用される化合物が用いられる（有機エレクトロニクス材料研究会編・「イメ−ジング用有機材料」・ぶんしん出版（１９９３年）・１８７〜１９２ページ参照、技術情報協会・「光硬化技術」・２００１年、に紹介されている光酸発生剤）。本発明に好適な化合物の例を以下に挙げる。第１に、ジアゾニウム、アンモニウム、ヨードニウム、スルホニウム、ホスホニウムなどの芳香族オニウム化合物のＢ（Ｃ_６Ｆ_５）_４ ⁻、ＰＦ_６ ⁻、ＡｓＦ_６ ⁻、ＳｂＦ_６ ⁻、ＣＦ_３ＳＯ_３ ⁻塩を挙げることが出来る。対アニオンとしてボレート化合物をもつものが酸発生能力が高く好ましい。オニウム化合物の具体的な例を以下に示す。
【０１０８】
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できる。具体的な化合物を以下に例示する。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できる。第４に、鉄アレン錯体を挙げることができる。
【０１０９】
以下に化合物例を示すが、本発明はこれらに限定されない。
【０１１０】
【化１５】

【０１１１】
【化１６】

【０１１２】
【化１７】

【０１１３】
【化１８】

【０１１４】
《光ラジカル発生剤》
本発明に用いられる光発生剤としては、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。
【０１１５】
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５μｍ〜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。
【０１１６】
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。
【０１１７】
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。
【０１１８】
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。
【０１１９】
《色材》
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できる各種色材を使用することができるが、耐候性の観点から顔料が好ましい。
【０１２０】
本発明で好ましく用いることのできる顔料を、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、
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・しわの発生の観点から、自ずと使用量に関しては制限がある。
【０１２１】
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できる。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。これらの分散剤および分散助剤は、顔料１００質量部に対し、１質量部〜５０質量部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、本発明に用いる照射線硬化型インクでは、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。
【０１２２】
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、インク透明性および硬化感度を維持することができる。
【０１２３】
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。
【０１２４】
《添加剤等》
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できる。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２００ｐｐｍ〜２００００ｐｐｍ添加することができる。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。
【０１２５】
これらの各種モノマー、色材としては、世界特許９９／２９７８７号、特開２００１−２２０５２６号に開示されているものなどが使用できる。その他、開始剤、添加剤等もこれらの文献を参考にできる。
【０１２６】
本発明に係る光硬化性インクとしては、カチオン重合性のインク、ラジカル重合性のインクを各々単独で使用することが可能であるが、両者を混合し、ハイブリッドインクとして使用することも可能である。
【０１２７】
本発明のインクジェットヘッドは、これらカチオン重合性及び／またはラジカル重合性のインクに適しているが、特にカチオン重合性インクを用いたときに、その優れた耐久性を発揮することができる。
【０１２８】
【発明の実施の形態】
以下、本発明の実施の形態について、図面を参照しながら説明をするが、本発明はこれらに限定されない。
【０１２９】
図１は、本発明の実施の形態におけるインクジェットヘッドの断面模式図である。図中、参照符号の１は油系インクの流路の三方の壁となる溝が切られた圧電性セラミックス基体（図２参照）、２は圧電性セラミックス基体１と接着されインク流路の一方の壁となる蓋部材、５は圧電性セラミックス基体１と蓋部材２とで形成されるインク流路である。以上がインクジェットヘッドのインクチャンバである。また、参照符号の１０はインクジェットヘッドの全体を覆うカバー、２０はマニホールド、２５はフィルタ、３０はマニホールド２０に接着され図示しないインク貯蔵部からインクを供給するためのインクチューブ、４０は図２で後述する電極膜３に通電するためのＦＰＣ（フレキシブルプリントサーキット）、４５はＦＰＣ４０に接着された駆動ＩＣ、５０はインクチャンバの前面に接着されインク滴を吐出させる吐出口を有するノズルプレート、Ｄは射出したインク滴である。図中の矢印はインクの流れを示している。
【０１３０】
図示しないインク貯蔵部から油系インクがインクチューブ３０を伝ってマニホールド２０を満たしている。マニホールド２０内には、金網等のフィルタ２５が配設され、油系インク中の異物を取り除くようになっている。フィルタ２５で濾過された油系インクは、インク流路５に流入している。一方、図示しないインクジェットプリンタ本体の制御手段から画像信号がＦＰＣ４０を伝って送られてくると、駆動ＩＣ４５は、対応するインクチャンバをせん断変形させるための電圧を発生させ、後述する電極膜３に通電する。すると、せん断変形したインクチャンバは、ノズルプレート５０の吐出口から、インク滴を射出することになる。
【０１３１】
図１において▲１▼〜▲９▼の斜線で示す部分は、インクジェットヘッドの構成部材の接着部である。▲１▼は圧電性セラミックス基体１と蓋部材２との接着部、▲２▼はインクチャンバとノズルプレート５０との接着部、▲３▼はＦＰＣ４０と圧電性セラミックス基体１上に付設された電極膜３（後述）との接着部、▲４▼はＦＰＣ４０と駆動ＩＣ４５との接着部、▲５▼はマニホールド２０と圧電性セラミックス基体１との接着部、▲６▼はマニホールド２０と蓋部材２との接着部、▲７▼はマニホールド２０内においてフィルタ２５との接着部、▲８▼はマニホールド２０とインクチューブ３０との接着部、▲９▼はＦＰＣ４０が圧電性セラミックス基体１から剥離しないように補強接着するための接着部である。
【０１３２】
接着部▲１▼および▲２▼は、可能な限り薄く、不必要な部分にはみ出さない事が必要である。最も接着精度が要求される部分である。
【０１３３】
接着部▲３▼はＦＰＣ４０が剥がれないように、伸び縮みの小さい接着剤を用いることが好ましい。
【０１３４】
接着部▲４▼は駆動ＩＣとの接点周囲であるので、ストレスに強い接着剤を用いることが好ましい。
【０１３５】
接着部▲７▼は、フィルタの目を詰まらせない様に接着剤の量を少量とすることが好ましい。
【０１３６】
上記全ての接着部において、圧電性セラミックス基体１の圧電性が消失しない低温・短時間で接着工程が行われること、硬化途中に接着部以外に流れ出さないことが必要である。
【０１３７】
また、接着部の色は無色でも有色でも構わない。
図２は、図１で示したインクチャンバの拡大断面模式図である。図２（ａ）は、インクの流通方向に対し垂直な断面から見た図、図２（ｂ）は、インク流路を溝状に形成した圧電性セラミックス基体の斜視模式図である。
【０１３８】
図中、１は圧電性セラミックス基体、２は他の壁を形成する蓋部材（代表的には、ガラス、セラミックス、金属或いはプラスチック製の平板を接着して形成するインク流路の蓋）、３は電極膜、４は保護膜、５はインク流路、▲１▼は接着層（図１の接着部▲１▼と同じ）を示す。
【０１３９】
圧電性セラミックス基体１を構成する圧電性セラミックスとしては、従来公知の任意のものを採用できるが、ＰＺＴ、ＰＬＺＴ等のセラミックスで、主にＰｂＯｘ、ＺｒＯｘ、ＴｉＯｘの混合微結晶体に、ソフト化剤又はハード化剤として知られる微量の金属酸化物、例えばＮｂ、Ｚｎ、Ｍｇ、Ｓｎ、Ｎｉ、Ｌａ、Ｃｒ等の酸化物を含むものが好ましい。
【０１４０】
ＰＺＴは、チタン酸ジルコン酸鉛であり、充填密度が大きく、圧電性定数が大きく、加工性が良いので好ましい。ＰＺＴは、焼成後、温度を下げると、急に結晶構造が変化して、原子がズレ、片側がプラス、反対側がマイナスという双極子の形の、細かい結晶の集まりになる。こうした自発分極は方向がランダムで、極性を互いに打ち消しあっているので、更に分極処理が必要となる。
【０１４１】
分極処理は、ＰＺＴの薄板を電極で挟み、シリコン油中に漬けて、１０〜３５ｋＶ／ｃｍ程度の高電界を掛けて、分極する。分極したＰＺＴに分極方向に直角に電圧を掛けると、側壁が圧電滑り効果により、斜め方向に、くの字形に、せん断変形してインク室の容積が膨張する。この分極処理による圧電性は、ＰＺＴにおいては、２００℃をキュリー点として、これ以上の温度を与えると消失してしまう。
【０１４２】
圧電性セラミックス基体１の密度〔ｇ／ｃｍ^２〕は、８．２であり、蓋部材２の密度〔ｇ／ｃｍ^２〕は、３以下としているが、蓋部材２の密度〔ｇ／ｃｍ^２〕は、より小さく例えば半分以下が好ましく、インクジェットヘッド全体が軽くなり、コンパクトなインクジェットヘッドができる。
【０１４３】
圧電性セラミックス基体１のヤング率または弾性係数〔ＧＰａ〕は、６５であり、蓋部材２のヤング率〔ＧＰａ〕は、１９０〜３９０としているが、２００以上が好ましく、圧電性セラミックス基体１の隔壁の変位を強固に支えることができ、且つ、自身の変形が少ないために、効率的な駆動ができ、低電圧化が可能である。
【０１４４】
圧電性セラミックス基体１の熱膨張係数〔ｐｐｍ／℃〕は、２であり、蓋部材２の熱膨張係数〔ｐｐｍ／℃〕は、０．６〜７としているが、両者の差が５以下、より好ましくは３以下であり、駆動時の発熱や、環境温度の変化に伴い、基板間の膨張によるそりやストレスでの破壊を防止できる。
【０１４５】
圧電性セラミックス基体１の熱伝導率〔Ｗ／ｃｍ・℃〕は、０．０１であり、蓋部材２の熱伝導率〔Ｗ／ｃｍ・℃〕は、０．０３〜０．３としているが、蓋部材２の熱伝導率〔Ｗ／ｃｍ・℃〕は、より大きく、大きいほど好ましく、圧電性セラミックス基体１の駆動時に発生する熱を蓋部材２を通して外部へ逃がすことができる。
【０１４６】
圧電性セラミックス基体１の誘電率は、３，０００であり、蓋部材２の誘電率は、４．０〜５０としているが、蓋部材２の誘電率は、小さいほど好ましく、好ましくは１０以下であり、圧電性セラミックス基体１を駆動するための電極パターンを蓋部材２上に設置することにより、圧電性セラミックス基体１自身の容量に加えて付加的な容量を発生させるので、インク室の容量を増大させ、発熱量を増大させ、駆動効率を低下させる。従って、蓋部材２の誘電率が小さい程付加容量を小さくできる。
【０１４７】
圧電性セラミックス基体１の硬度〔Ｈｖ〕は、５００であり、蓋部材２の誘電率は、１，０００以上としているが、蓋部材２の誘電率は、より大きく、好ましくは１倍以上、より好ましくは１．５倍以上であり、製造工程での欠け等で歩溜り劣化を防止できる。
【０１４８】
圧電性セラミックス基体１の曲げ強さ〔ＭＰａ〕は、１００であり、蓋部材２の曲げ強さ〔ＭＰａ〕は、３００〜９００としているが、好ましくは２倍以上であり、蓋部材２のそりや曲げに強い程、長尺のインクジェットヘッドを安定して作製できる。
【０１４９】
圧電性セラミックス基体１の体積抵抗率〔Ω・ｃｍ〕は、１であり、蓋部材２の体積抵抗率〔Ω・ｃｍ〕は、７〜１０としているが、より大きいことが好ましく、電子デバイスとしてのリーク電流を減らすために大きい程良い。
【０１５０】
また、蓋部材２と圧電性セラミックス基体１との間の接着面の表面粗さＲａは、１．０μｍ以下であり、好ましくは０．３μｍ以下、更に好ましくは０．１μｍが好ましく、接着表面の表面粗さＲａが１．０μｍを越えると、接着面に接着剤が多数入り込み、圧電性セラミックスの駆動力が低下し、感度低下、電圧上昇を引き起こし、好ましくない。
【０１５１】
また、蓋部材２と圧電性セラミックス基体１との間の接着面は、プラズマ処理またはＵＶ処理される。プラズマ処理は、真空チャンバー中に蓋部材２や圧電性セラミックス基体１を置き、Ａｒ、Ｎ_２、Ｏ_２の１つまたは混合ガスを注入し、外部からの電磁界で、プラズマ状態にする処理であり、表面のエッチング性を高めるために、ＣＦ_４等のフッ素系炭化水素ガスを用いても良い。また、ＵＶ処理は紫外線発光ランプを直接蓋部材２や圧電性セラミックス基体１に照射する処理であり、オゾンでのクリーニング効果を出すために、Ｏ_２雰囲気下でも良い。このように接着面をプラズマ処理及びＵＶ処理をすることにより、有機物汚染を洗浄除去でき、接着面全体への接着剤のぬれ性を向上させ、微小な泡残り等の接着不良を排除でき、それにより、圧電性セラミックス基体１の駆動不良をなくし、安定なインクジェットヘッドを製造できる。
【０１５２】
圧電性セラミックス基体１は、例えば、厚さ１ｍｍの基体１の一面に微少な溝部（Ｌ：３０ｍｍ、Ｈ：３６０μｍ、Ｂ：７０μｍ）が加工されている。この基体１の加工面に蓋部材２を接合（接着）することにより、インク流路となるインクチャンバ（Ｌ：３０ｍｍ、Ｈ：３６０μｍ、Ｂ：７０μｍ）が溝部に構成される。インクチャンバの一端はフィルタユニットを含むマニホールドを介してインク貯蔵部に連結され、他端はインク吐出口（ノズルプレート）と連結される。
【０１５３】
又、電極膜３は微細な部材に薄膜で形成する（通常、０．５〜５．０μｍ程度）ため、スパッタリング等により形成するが、電気的特性、耐蝕性及び加工性の点からアルミニウム、タンタル又はチタニウムからなることが好ましい。又、電極膜の耐蝕性及び安定性を向上するのに陽極酸化処理を施すのが有効である。陽極酸化処理の具体例を次に示す。
【０１５４】
電解液として、３００ｍｌのエチレングリコール及び３０ｍｌの３％酒石酸からなるｐＨ７．０±０．５（アンモニア水で調整）の液を用い、厚さ２．０μｍのアルミニウム電極膜を形成した圧電性セラミックス基体１を浸漬し、電極膜側をプラスにして電流密度１ｍＡ／ｃｍ^２で電圧が１００Ｖに達するまでは定電流で、電圧１００Ｖに達した後は１００Ｖの定電圧で陽極酸化を行い、電流密度が０．１ｍＡ／ｃｍ^２以下となったとき処理を終了させる。
【０１５５】
本実施の形態においては、上記電極膜の陽極酸化処理後、保護膜４の形成工程前に蓋部材２を圧電性セラミックス基体１に接着する。該接着工程では、接着剤を塗布する前に、圧電性セラミックス基体１の溝部が設けられた加工面及び前記溝部を覆う蓋部材２の接合面はその状態に応じて洗浄、研磨等の前処理が行われ、接着面がそれぞれ形成される。
【０１５６】
圧電性セラミックス基体１の接着面と蓋部材２の接着面とが接着剤で接着されて、圧電性セラミックス基体１と蓋部材２は一体に組み立てられる。
【０１５７】
圧電性セラミックス基体１と蓋部材２の組立後、接着面は加圧状態で、接着剤の硬化温度まで加熱され、さらにこの加圧・加熱状態が約２時間保持されて、接着剤が硬化される。この接着工程により接着層が接着面に形成され、また一体化された圧電性セラミックス基体１と蓋部材２間にインク流路５となるインクチャンバが構成される。
【０１５８】
接着工程終了後一体化された圧電性セラミックス基体１と蓋部材２に対し、ＣＶＤ法等にて樹脂層である保護膜４を形成する。
【０１５９】
本実施の形態において、圧電性セラミックス基体１と蓋部材２の接着部に使用される接着剤は、下記条件１を満たすエポキシ系接着剤またはウレタン系接着剤である。
【０１６０】
《条件１》
粘度　　：３０Ｐａ・ｓ〜５００Ｐａ・ｓ
硬化温度：１２０℃以下
吸油率　：５％以下
上記粘度は、ＪＩＳ−Ｋ７１１７に規定される測定方法にて求められる値であり、本発明に使用される接着剤において、好ましくは３０Ｐａ・ｓ〜１００Ｐａ・ｓ、より好ましくは３０Ｐａ・ｓ〜５０Ｐａ・ｓである。
【０１６１】
上記硬化温度は、樹脂を硬化（分子を３次元化）させ、接着を完成させるために必要な温度であり、接着剤の種類および組成に依存する。本発明に使用される接着剤において、硬化温度は、好ましくは１００℃以下である。
【０１６２】
上記吸油率は、ＪＩＳ−Ｋ７２０９に規定される吸水率の測定方法に準じ、浸漬液を油系インクに変更したものである。ここで、吸油率を測定する際に使用する油系インクは、当該インクジェットヘッドが用いる油系インクであることが最も好ましいが、以下に示す条件ＡおよびＢを満たしている油系インクであれば構わない。
【０１６３】
条件Ａ：炭素数１５〜１８の飽和炭化水素、または、炭素数１５〜１８の単価アルコール、もしくは、それらの誘導体を溶媒として、８０質量％以上含有する
条件Ｂ：色剤を含有する
本発明に使用される接着剤において、吸油率は、好ましくは２％以下、さらに好ましくは１％以下である。
【０１６４】
また、本発明に使用される接着剤は、さらに以下の条件２を満たすエポキシ系接着剤またはウレタン系接着剤であることが好ましい。
【０１６５】
《条件２》
熱膨張率；１００ｐｐｍ
上記熱膨張率は、物体の温度を１度上昇させたときの長さ変化（線膨張）を指し、ＪＩＳ−Ｋ７１９７で規定される測定方法によって測定される値である。例えば、接着剤自体の温度が１度上昇すると、寸法が１ｍ当たり、０．００１ｍｍ膨張する場合、当該接着剤の熱膨張率は、１ｐｐｍということになる。
【０１６６】
当然ながら、この膨張率は、硬化後の乾燥した接着剤におけるものである。
本発明に使用される接着剤において、熱膨張率は、好ましくは８５ｐｐｍ以下、さらに好ましくは６０ｐｐｍ以下である。
【０１６７】
上記条件１および２を満たすエポキシ系接着剤としては、セメダイン社製のＥＰ−３３０，ＥＰ−３３１，１５００，ＣＳ２３４０−５等が好ましく用いられる。
【０１６８】
また、上記条件１および２を満たすウレタン系接着剤としては、日本ＮＳＣ社製のＫＢＫ，ＥＲＩ，１０Ｌ，１３，ＥＴ６０（エポキシ・ウレタン系）、住友スリーエム社製のＴＥ−１００，ＴＥ−２００、コニシ社製のボンドＫＵ６６１／６６２、サンスター技研社製のペンギンセメント♯９９０Ａ、東亜合成社製のアロンメルトＲ−２０３０等が好ましく用いられる。
【０１６９】
上記本発明に係る接着剤において、好ましく用いられるものは、エポキシ系接着剤であり、その中で特に好ましくは、セメダイン社製ＥＰ−３３０，ＥＰ−３３１である。
【０１７０】
また、本発明に係る接着剤をインクジェットヘッドの構成部材に塗布し、接合したときの接着層の乾燥膜厚は、１００μｍ以下であることが好ましく、さらに１０μｍ以下であることが好ましい。
【０１７１】
また、本発明に係る接着剤をインクジェットヘッドの構成部材に塗布する方法としては、周知の方法を用いることが出きるが、膜厚を精度良くコントロールするには、ディスペンサ法、スクリーン法あるいはロール転写法が好ましい。
【０１７２】
【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。
【０１７３】
実施例１
《インクジェットヘッド１、２の作製》
表１に示すような構成部材を用いて、図１に示したような形態を有する、インクジェットヘッド１（本発明）、インクジェットヘッド２（比較例）を各々作製した。
【０１７４】
《インクジェットインクの調製》
下記のように、マゼンタ顔料分散物を作製し、次いで、得られたマゼンタ顔料分散物を用いて、マゼンタインク（インク浸漬試験においても、浸漬液として使用する）を調製した。
【０１７５】
（ａ）マゼンタ顔料分散物の調製
以下の配合でマゼンタ顔料分散物を得た。
【０１７６】

（ｂ）マゼンタインクの調製
上記で得られたマゼンタ顔料分散物を用い、下記の配合を行い、０．８μｍのメンブレンフィルターにて濾過、５０℃に加熱しながら減圧条件下で脱水を行い、マゼンタインクを得た。
【０１７７】
（マゼンタインクの組成）
マゼンタ顔料分散物　　　　　　　　　　　　　　　　　　　１７質量部
アロンオキセタンＯＸＴ−２２１（東亜合成）　　　　　　　７０質量部
セロキサイド２０２１Ｐ（ダイセルＵＣＢ）　　　　　　　　３０質量部
ＵＶＩ−６９９０（ダウケミカル製、光酸発生剤）　　　　　　５質量部
《インクジェットヘッドの各構成部材のインク浸漬評価》
得られたインクジェットヘッド１、２の各々について、上記のマゼンタインクを浸漬液として用い、前述のインク浸漬試験を行い、インクジェット各構成部材の質量変化率（％）を求めた。得られた結果は表１に示す。
【０１７８】
《インクジェットヘッドの連続出射試験》
インクジェットヘッド１、２の各々について、下記のようにして連続出射試験を行った。
【０１７９】
図１に示すようなインクジェットヘッド１、２を各々用いて、図２に示すように、圧電性セラミックス基体１と蓋部材２とを従来公知の接着剤を用いて接着させ、インクジェットヘッドのインクチャンバ１、２を、各々作製した。
【０１８０】
上記作製したインクチャンバ１、２を各々有するインクジェットヘッド１、２を、各々インクジェットプリンタ（オリンパス社製ＰＪ５４００）に装着し、上記マゼンタインク（インク浸漬試験用にも使用）をインク温度５０℃に保ちながら、連続印字試験を行った。
【０１８１】
尚、接着剤の詳細は下記の通りである。
主剤　：ＤＧＥＢＡ＋フェノールノボラック型エポキシ樹脂の混合物
硬化剤：脂肪族ポリアミン
ＤＧＥＢＡ：ビスフェノールＡジグリシジルエーテル
得られた結果を表１に示す。
【０１８２】
【表１】

【０１８３】
表１から、比較のインクジェットヘッド２に比べて、インクジェットヘッドの各構成部材の質量変化率が、−０．８質量％〜８．０質量％の範囲に調整した、本発明のインクジェットヘッド１は、５００時間という長時間の連続出射試験においても、安定な出射が可能であることが判る。
【０１８４】
実施例２
《インクジェットヘッド１Ａの作製》
実施例１に記載のインクジェットヘッド１の作製において、接着剤（主剤＋硬化剤）の硬化温度を３０℃から１５℃に変更した以外は同様にして、インクジェットヘッド１Ａを作製した。
【０１８５】
《エポキシ系接着剤使用時の浸漬試験結果とインク感度評価》
実施例１に記載のインクジェットヘッド１、上記で得られたインクジェットヘッド１Ａについて、実施例１と同様にしてインク浸漬試験を行った後の各々のマゼンタインク１、１Ａについて、インクの硬化感度測定し、インクジェットヘッドの構成部材の１つであるエポキシ接着剤のインク硬化感度への影響を調べた。
【０１８６】
硬化感度への影響の大きさについては、インク浸漬試験前のマゼンタインク（ブランクインク）の硬化感度を指標とした。また、硬化感度の測定は下記のように行った。
【０１８７】
（硬化感度の測定）
ＰＥＴ（ポリエチレンテレフタレート）フィルム上に、インクを６μｍの厚さで付着させ、２５４ｎｍの蛍光灯、照射面照度１０ｍＷ／ｃｍ^２の条件で測定し、表面タックの消失するエネルギー量を硬化感度指標とした。
【０１８８】
得られた結果を下記に示す。

尚、エポキシ系接着剤の３０℃硬化条件でのインク浸漬試験後の質量変化率は、−０．５、１５℃硬化条件での質量変化率は、−１．２である。
【０１８９】
上記結果から、２０℃硬化条件のような、硬化不十分な接着剤を用いているインクジェットヘッド１Ａでは、硬化感度（インク感度ともいう）が低下しているが、これは、未硬化のアミン類が溶出し、インク感度を低下させるものと本発明者等は推察している。
【０１９０】
【発明の効果】
本発明により、光硬化性インクに対する耐蝕性が向上し、インクノズルの詰まりや、インク漏れが起こらず、インク滴吐出精度が高く、インク感度への影響も軽減されたインクジェットヘッド及び、インクジェット記録方法を提供することが出来た。
【図面の簡単な説明】
【図１】本発明の実施の形態におけるインクジェットヘッドの断面模式図である。
【図２】図１で示したインクチャンバの拡大模式図である。
【符号の説明】
１　圧電性セラミックス基体
２　蓋部材
５　インク流路
１０　カバー
２０　マニホールド
２５　フィルタ
３０　インクチューブ
４０　ＦＰＣ
４５　駆動ＩＣ
５０　ノズルプレート
Ｄ　インク滴
▲１▼〜▲９▼　接着部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inkjet head and an inkjet recording method using the inkjet head.
[0002]
[Prior art]
Conventionally known ink jet recording methods include a method using various inks such as an aqueous ink, an oil-based ink, a solvent ink, and a photo-curable ink (for example, an ultraviolet-curable ink).
[0003]
As a component of the ink jet head used for ink jet recording, many printers have been put into practical use with respect to the above-described aqueous ink, oil-based ink, and solvent ink. Constituent members that can obtain the durability of the head have been developed (for example, see Patent Documents 1 and 2).
[0004]
2. Description of the Related Art In recent years, an ink jet recording method using a photocurable ink has attracted attention as a method for forming an image even on a substrate having poor ink absorption.
[0005]
These include a solvent type in which a reactive monomer is diluted with water, an aqueous solvent, and various organic solvents, and a solventless type in which no solvent remains after curing. In recent years, solvent-free ink has attracted attention due to the demand for VOC-free ink.
[0006]
Photocurable inks that cure ink by light such as ultraviolet rays or EB (ultraviolet rays, near infrared rays, electron beams, etc.) include radically polymerizable inks mainly composed of acrylate monomers and epoxy monomer or oxetane monomers. Cationic polymerizable inks are known.
[0007]
However, acrylate monomers, epoxy monomers, oxetane monomers, etc., exhibit properties that are significantly different from those of diluent solvents used in conventional aqueous inks, oil-based inks, and solvent inks. Had many problems. Monomers have properties close to those of plasticizers used as plastic additives, and are easily compatible with many plastics.
[0008]
These monomer components are much easier to dissolve and swell the components of the inkjet head than conventional diluting solvents. It has been found that problems such as variations in the injection characteristics of the ink and nozzle clogging due to aggregation and sedimentation of the pigment due to the eluted components occur.
[0009]
Above all, the photocurable ink has a high viscosity, and it is necessary to obtain ejection stability by heating the ink and lowering the viscosity, but the problem that the corrosion resistance of the ink is further required by the heating. In addition, it has been pointed out that a problem peculiar to the photocurable ink is that the curing sensitivity is reduced by light depending on the eluted component.
[0010]
Among the photo-curable inks, cationically polymerizable inks using epoxy monomers, oxetane monomers, vinyl ether monomers, etc., have high touch resistance of various head components, and are likely to affect the curing sensitivity. Have problems.
[0011]
[Patent Document 1]
JP 2001-301160 A
[0012]
[Patent Document 2]
JP 2001-301178 A
[0013]
[Problems to be solved by the invention]
An object of the present invention is to improve the corrosion resistance to photocurable ink, prevent clogging of ink nozzles and ink leakage even when used for a long time, ensure stable ink droplet ejection accuracy, and affect ink sensitivity. And an inkjet recording method using the inkjet head.
[0014]
[Means for Solving the Problems]
The above object of the present invention has been achieved by the following constitutions 1 to 7.
[0015]
1. An ink jet head of a photocurable ink, wherein when the constituent members constituting the ink jet head are each subjected to an ink immersion test, the mass change rate of the constituent members is -0.8% by mass to 8.0% by mass. % Of the ink jet head.
[0016]
2. 2. The inkjet head according to the item 1, wherein a mass change rate in the ink immersion test is -0.2% by mass to 5.0% by mass.
[0017]
3. The constituent members include PE (polyethylene), polypropylene, PET (polyethylene terephthalate), PBT (polybutylene terephthalate), nylon, TFE (tetrafluoroethylene), PFA (perfluoroalkoxyethylene copolymer), and FEP (fluorinated ethylene). The inkjet according to 1 or 2, wherein the inkjet is at least one material selected from the group consisting of propylene), perfluoroelastomer, polyparaxylylene, epoxy adhesive, SUS, and PI (polyimide). head.
[0018]
4. At least one of the constituent members is a nozzle plate, the nozzle plate contains at least PI (polyimide), and an impurity ion concentration of the PI (polyimide) is 1.0 ppm or less. The inkjet head according to any one of claims 1 to 3.
[0019]
5. The inkjet head according to any one of the above items 1 to 4, wherein the inkjet head is of a shear deformation type that discharges ink by shear deformation of a piezoelectric ceramic.
[0020]
6. An inkjet recording method using the inkjet head according to any one of the above items 1 to 5.
[0021]
7. 7. The ink jet recording method according to the item 6, wherein a cationically polymerizable ink is used as the photocurable ink.
[0022]
Hereinafter, the present invention will be described in detail.
<< Components of inkjet head >>
The constituent members of the inkjet head according to the present invention will be described.
[0023]
Examples of the constituent members of the inkjet head according to the present invention include conventionally known constituent members of an inkjet head. For example, a manifold, an ink tube, a filter, a piezoelectric ceramic substrate, a lid member, an adhesive, an O-ring, and a protective member are provided. Examples include a film, an electrode film, a nozzle plate, and a NWC (non-wet coating) material.
[0024]
Here, the constituent member of the inkjet head according to the present invention refers to a member that constitutes a portion that comes into contact with the photocurable ink when the photocurable ink is filled (during an ink immersion test).
[0025]
The details of the ink jet head including these components will be described later.
(Materials for components)
The materials (organic compounds, polymer materials, inorganic compounds, metal compounds, etc.) used for producing the components constituting the inkjet head of the present invention as described above are obtained after the ink immersion test as described in claim 1. It is an essential requirement that the mass change rate be in the range of -0.8 mass% to 8.0 mass%, but preferably, the mass change rate is -0.2 mass% to 5.0 mass%. Range. The details of the ink immersion test according to the present invention will be described later.
[0026]
Each component of the inkjet head of the present invention is a material for adjusting the mass change rate after the ink immersion test so as to fall within the range of the above-mentioned mass change rate. For example, conventionally known materials such as polyethylene, polypropylene, PET (polyethylene terephthalate), PBT (polybutylene terephthalate), nylon, TFE (tetrafluoroethylene), PFA (perfluoroalkoxyethylene copolymer), and FEP ( Fluorinated ethylene propylene), perfluoroelastomer, polyparaxylene, epoxy adhesive, SUS, PI (polyimide). Of these, PET (polyethylene terephthalate), PBT (polybutylene terephthalate), nylon, TFE (tetrafluoroethylene), PFA (perfluoroalkoxyethylene copolymer), FEP (fluoroethylene propylene), Fluoroelastomer, SUS, PI (polyimide) and the like.
[0027]
On the other hand, when used as a constituent member of the ink jet head of the present invention, examples of unfavorable members include acrylics such as ABS, PEI, PVC, various plastics containing a plasticizer, and elastomers such as SBR, NBR and EPDM. .
[0028]
When cationically polymerizable monomers, for example, oxirane group-containing monomers, oxetane-containing monomers, and vinyl ethers are used as the ink, the monomers are easily impregnated and swelled, so that deformation occurs, and particularly, elastomers and plasticizer-containing plastics are used. Have problems such as easy swelling and easy elution of the plasticizer.
[0029]
(adhesive)
As the adhesive, an epoxy-based or urethane-based adhesive is preferable, and among them, an epoxy-based adhesive is preferably used. As the epoxy-based adhesive, for example, a two-part room-temperature curing type EP-330, EP-331 or 1500 manufactured by Cemedine Co., Ltd. can be used. As the urethane-based adhesive, Alonmelt R-2300 manufactured by Toa Gosei Co., Ltd., and Penguin Cement # 990A manufactured by Sunstar Giken Co., Ltd. can be used.
[0030]
In the present invention, when an epoxy-based adhesive is used, when a two-component curable member is used as the epoxy adhesive, it is necessary to select a material and curing conditions so that the mass change rate described in claim 1 is achieved. is there.
[0031]
When curing failure occurs during curing, uncured amines are eluted, the mass change rate after ink immersion becomes less than -0.8% by mass, and the eluted amines such as pigments in the ink Problems such as aggregation of the coloring material are caused, and when the cationically polymerizable ink is used, sensitivity is reduced.
[0032]
(Protective film)
As a material of the protective film, PI (polyimide), PMMA (polymethyl methacrylate), and polyparaxylylene can be preferably used.
[0033]
(Manifold)
As the material for the manifold, PET (polyethylene terephthalate), PBT (polybutylene terephthalate), and nylon can be preferably used.
[0034]
(filter)
As a material of the filter, SUS or nylon can be preferably used.
[0035]
(Nozzle plate)
As a material for the nozzle plate, PI (polyimide) or SUS can be preferably used.
[0036]
(NWC (Non-wet coating))
As NWC for imparting ink repellency to the nozzle plate, TFE, PFA, FEP, fluorine-modified PI (polyimide) and the like are preferable.
[0037]
(FPC (Flexible Print Circuit))
As a material of the FPC (flexible print circuit), PI (polyimide) can be preferably used.
[0038]
(External members such as covers)
POM (polyoxymethylene), HDPE (high-density polyethylene), and PPE (polyphenylene ether) can be preferably used as a material of a cover as an external member for protecting the inkjet head.
[0039]
<< PI (polyimide) >>
Here, PI (polyimide) preferably used for the component according to the present invention will be described.
[0040]
The solvent-soluble PI (polyimide) used in the present invention is specifically described in the following literature. E. FIG. S. Moyer, D .; K. Mohanty, C.M. A. Arnold, J .; E. FIG. McGrath; "Synthesis and Characterization of of Soluble Polyimide Homo-and Copolymers"; Polymeric Materials; Science &Engineering;Pharmaceuticals; Spring @ 1989. M. E. FIG. Rodgers, C.A. A. Arnold, J .; E. FIG. McGrath; "Soluble, ProcessablePolyimide @ Homopolymers @ Copolymers"; Polymer @ Preprints, ACS @ Divisionof @ Polymer @ Chemistry; V30-1; p. 296; Y. Oishi, M .; Xie, M .; Kakimoto, Yoshio; "Syntheses and Characterizationof Soluble Arumatic Polyamides and Polyimides from 1,1- (Bis (4-Aminophenyl)) - 2,2-diphenylethylene"; Polymeric Materials: Science & Engineering Proceedings of ACS Division of Polymeric Materials; V60; p. 757-761; Spring @ 1989. F. W. Harris, Y .; Sakaguchi; "SolubleAromatic @ Polyimides @ Derived @ from @ NewPhenylated @ Diamines": Polymeric @ Materials; Science & Engineering @ ProfessionalScience. 187-192; Spring @ 1989.
The polyimide used in the present invention is synthesized from tetracarboxylic dianhydride and diamine. Although there is no particular limitation on the tetracarboxylic dianhydride used, examples of useful dianhydrides in the present invention include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetraanhydride. Carboxylic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 3,3', 4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,3 ', 4 4'-diphenylethertetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylmethanetetracarboxylic dianhydride, 2,3,3', 4'-biphenyltetracarboxylic dianhydride, 2,3 , 3 ', 4'-diphenylethertetracarboxylic dianhydride, 2,3,3', 4'-benzophenonetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, , 4,5 7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propanoic dianhydride, 2,2- Bis (3,4-dicarboxyphenyl) hexafluoropropanoic dianhydride, 4,4'-bis (3,4-dicarboxyphenyl) diphenyl sulphidic dianhydride, 1,3-diphenylhexafluoropropane-3 , 3,4,4-tetracarboxylic dianhydride, 1,4,5,6-naphthalenetetracarboxylic dianhydride, 2,2 ', 3,3'-diphenyltetracarboxylic dianhydride, 3, 4,9,10-berylene tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride Naphthalene-1,4,5,8-tetracarboxylic dianhydride, decahydronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5 6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloro Naphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, phenanthrene-1,8, 9,10-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, pyrazine-2, 3,5,6-tetracarboxylic acid Hydrate, 2,2-bis (2,3-dicarboxyphenyl) propanoic dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethaneic dianhydride, 1,1-bis (3 , 4-Dicarboxyphenyl) ethanoic dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, derivatives thereof And mixtures thereof.
[0041]
Tetracarboxylic dianhydrides particularly advantageous for obtaining solvent-soluble polyimides are not particularly limited, but include biphenyltetracarboxylic dianhydride, benzophenonetetracarboxylic dianhydride, 4,4 '-[2,2, 2-trifluoro-1- (trifluoromethyl) ethylidene] bis (1,2-benzene) dicarboxylic dianhydride, bis (dicarboxyphenyl) ether dianhydride, bicyclo [2.2.2] oct-7 -Ene-2,3,5,6-tetracarboxylic dianhydride and the like. These can be used alone or as a mixture of two or more to form a polyimide composition.
[0042]
Although there is no particular limitation on the diamine used, examples of preferred diamines in the practice of the present invention include 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, and 3,3 '. -Dimethoxy-4,4'-diaminobiphenyl, 4,4'-diaminoparaterphenyl, 4,4'-bis (4-aminophenoxy) -biphenyl, 4,4'-diaminodiphenylsulfone, 3,3'- Diaminodiphenyl sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [2- (aminophenoxy) phenyl] sulfone, 1,4-bis ( 4-aminophenoxy) benzene, 2,2'-dichloro-4,4'-diamino-5,5'-dimethoxybiphenyl 2,2 ', 5,5'-tetrachlorobenzidine, 9,10-bis (4-aminophenyl) anthracene, o-tolidine sulfone, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenyl) benzene, bis [4- (aminophenoxy) phenyl] ether, 4,4'-diaminodiphenylmethane, bis (3-ethyl-4-amino Phenyl) methane, bis (3-methyl-4-aminophenyl) methane, bis (3-chloro-4-aminophenyl) methane, 2,2 ', 5,5'-tetrachloro-4,4'-diaminobiphenyl 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4 ' Diaminodiphenylmethane, 4,4'-diaminooctafluorobiphenyl, metaphenylenediamine, 2,2-bis [(4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexa Fluoropropane, 2,2-bis (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 2,2-bis (3-hydroxy-4-aminophenyl) propane, 2, 2-bis (3-hydroxy-4-aminophenyl) hexafluoropropane, 9,9-bis (4-aminophenyl) -10-hydroanthracene, orthotrizine sulfone, 3,3 ', 4,4'-biphenyltetramine, 3,3 ', 4,4'-tetraaminodiphenyl ether, diaminoanthraquinone 1,5-diaminoanthraquinone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (2-aminophenoxy) phenyl] sulfone, 3,3'-dichloro-4,4'-diaminobiphenyl, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 4,4'-diaminobiphenyl, 9,9-bis (4-aminophenyl) fluorene 4,4'-dimethyl-3,3'-diaminodiphenylsulfone, 3,4'-bisaniline A, bisaniline M, bisaniline P, methylene-bis-2,6-xylidine, 4-diaminocumene, 2,5- Dichloro-p-phenylenediamine, 2,6-dichloro-p-phenylenediamine, 2,5-dimethyl-p-phenylene Amine, 2-chloro-p-phenylenediamine, 4-chloro-m-phenylenediamine, 5-chloro-2-methyl-p-phenylenediamine, acetoguanamine, 2,3,5,6-tetramethyl-p-phenylene Diamine, 2,4,6-trimethyl-m-phenylenediamine, bis-3-aminopropyl-tetramethyldisiloxane, 2,7-diaminofluorolen, 2,5-diaminoviridine, p-phenylenediamine, 1,2 -Bis (anilino) ethane, diaminobenzanilide, diaminobenzoate, 1,5-diaminonaphthalene, diaminotoluene, diaminobenzotrifluoride, diaminoanthraquinone, 1,3-bis (anilino) hexafluoropropane, 1,4-bis ( Anilino) octafluorobutane, 1,5-bis Anilino) decafluoropentane, 1,7-bis (anilino) tetradecafluoroheptane, 2,2-bis [4- (3-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (2 -Aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) -3,5-ditrifluoromethylphenyl] hexalfluoropropane, p-bis (4-amino-2-tri Fluoromethylphenoxy) benzene, 4,4'-bis (4-amino-2-trifluoromethylphenoxy) biphenyl, 4,4'-bis (4-amino-3-trifluoromethylphenoxy) biphenyl, 4,4 ' -Bis (4-amino-2-trifluoromethylphenoxy) diphenylsulfone, 4,4'-bis (3-amino- 5-trifluoromethylphenoxy) diphenyl sulfone, 2,2-bis [4- (4-amino-3-trifluoromethylphenoxy) phenyl] hexafluoropropane, 3,3 ′, 5,5′-tetramethylbenzidine, 3,3'-dimethoxybenzidine, o-tolidine-m-tolidine, 2,2 ', 5,5', 6,6'-hexafluorotrizine, and 4,4 '"-diaminoquaterphenyl, and mixtures thereof It is.
[0043]
Particularly advantageous diamines include, but are not limited to, 1,4-benzenediamine, 6-methyl-1,3-benzenediamine, 4,4'-diamino-3,3'-dimethyl-1,1'-biphenyl, 4,4'-amino-3,3'-dimethoxy-1,1'-biphenyl, 4,4'-methylenebis (benzeneamine), 4,4'-oxybis (benzeneamine), 3,4'-oxybis ( Benzenamine), 4,4'-thiobis (benzeneamine), 4,4'-sulfonyl (benzeneamine), 3,3'-sulfonyl (benzeneamine), 1-trifluoromethyl-2,2,2-triamine Fluoroethylidine-4,4'-bis (benzeneamine), 2,2'-bis (4- (4-aminophenoxy) phenyl) sulfone, bis (4- (3-aminophenoxy) phene B) sulfone, 1,3-bis [1- (4-aminophenyl) -1-methylethylidene] benzene, 1,4-bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) Benzene, 9,9-bis (4-aminophenyl) fluorenediaminosiloxane and the like can be mentioned. These can be used alone or as a mixture of two or more to form a polyimide composition.
[0044]
The polyimide may be a block copolyimide composed of three or more components synthesized via a polyimide oligomer. If an appropriate component is used in the block copolyimide, desirable solvent solubility, electrophoresis, heat resistance, hydrophilicity, mechanical properties and the like can be satisfied at the same time.
[0045]
In order to produce a polyimide having improved mechanical strength, heat resistance, heat aging resistance and processability, an oligomer of sulfonamide is produced, and then an acid dianhydride is added to obtain a blockable polyimide resin.
[0046]
Further, in a polar solvent, 1.5 to 2.0 moles of an acid dianhydride is added to a diamine and reacted at a low temperature to synthesize an amide acid oligomer. When an equivalent amount of isocyanate is added thereto and reacted, a polyimide amide carboxylic acid is obtained while generating carbon dioxide gas.
[0047]
Also, in order to obtain a polyimide film having good substrate adhesion, an acid dianhydride is added to a diaminosiloxane copolymer to form a siloxane-amic acid block copolymer, and an equivalent amount of a diamine is added thereto to obtain a polyamic acid. The siloxane-imide block copolymer can then be produced by heat or chemical treatment.
[0048]
Further, an acid dianhydride is added to the aromatic diamine in an excess or an under amount, and the acid dianhydride is reacted to produce a polyamic acid prepolymer, and then a shortage of the diamine is added to obtain a polyamic acid copolymer, The polyimide copolymer can then be produced by chemical or heat treatment, in which the polyamic acid is passed through as an intermediate, thus preventing the exchange reaction of the resulting polyamic acid even when two different block polymers are combined. Therefore, it becomes a block polymer with randomness.
[0049]
The electrodepositable polyimide can be obtained by using an acid dianhydride or diacid into which a substituent that ionizes to give a cation or an anion is introduced. As a substituent for providing a cation, for example, a trifunctional blocked isocyanate or a prepolymer of isocyanate is mixed with a polymer having a hydroxyl group or an amine group as a functional group, and then co-dispersed in a water / acid solution.
[0050]
Primary, secondary and tertiary amines, quaternary ammonium salts, quaternary ammonium hydroxides, quaternary phosphates, tertiary sulfates, quaternary which become water-soluble by the addition of acids And ammonium carboxylate. In order to obtain a cationically electrodepositable polyimide, such a substituent may be introduced into a polyimide chain. Most preferably, 2,6-diaminopyridine is used as part of the diamine component.
[0051]
The substituent providing an anion is preferably a carboxyl group. Such a substituent may be introduced into the polyimide chain in order to obtain an anionic electrodepositable polyimide. The most preferred aromatic diamine used for the polyimide requires coexistence of an aromatic diaminocarboxylic acid.
[0052]
Examples of the aromatic diaminocarboxylic acid include 3,5-diaminobenzoic acid, 2,4-diaminophenylacetic acid, 2,5-diaminoterephthalic acid, 3,5-diaminoparatoluic acid, and 3,5-diamino-2-naphthalene. There are carboxylic acid, 1,4-diamino-2-naphthalenecarboxylic acid and the like, and 3,5-diaminobenzoic acid is particularly preferably used.
[0053]
《Light curable ink》
The materials used for preparing the photocurable ink according to the present invention will be described.
[0054]
The photocurable ink according to the present invention preferably contains an epoxy compound, an epoxidized oil, an oxetane compound, an aprotic solvent, a radical polymerizable monomer, a coloring material, and other additives as shown below as constituent components. .
[0055]
As the cationic polymerizable compound, an epoxy compound, an epoxidized oil, an oxetane compound, or the like can be used. As the radical polymerizable compound, the following radical polymerizable monomers can be used.
[0056]
《Epoxy compound》
The epoxy compound according to the present invention will be described.
[0057]
Preferred as aromatic epoxides are di- or polyglycidyl ethers produced by the reaction of 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 thereof 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.
[0058]
The alicyclic epoxide is 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. Compounds containing cyclohexene oxide or cyclopentene oxide are preferred.
[0059]
Preferred examples of the aliphatic epoxide include di- or polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof, and typical examples thereof include diglycidyl ether of ethylene glycol, diglycidyl ether of propylene glycol and Diglycidyl ethers of alkylene glycols such as diglycidyl ether of 1,6-hexanediol, polyglycidyl ethers of polyhydric alcohols such as di- or triglycidyl ether of glycerin or alkylene oxide adduct thereof, polyethylene glycol or alkylene oxide adduct thereof Of polyalkylene glycols such as diglycidyl ethers of polypropylene glycol or diglycidyl ether of an alkylene oxide adduct thereof Glycidyl ether, and the like. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.
[0060]
Among these epoxides, in consideration of the rapid curing property, an aromatic epoxide and an alicyclic epoxide are preferable, and an alicyclic epoxide is particularly preferable. In the present invention, one of the above epoxides may be used alone, or two or more may be used in appropriate combination.
[0061]
《Epoxylated oil》
Among the epoxy compounds described above, the following epoxidized oils are preferably used in the present invention.
[0062]
The epoxidized oil according to the present invention is an epoxidized oil or fat obtained by epoxidizing an oil or fat containing an unsaturated fatty acid, such as epoxidized soybean oil, epoxidized anima oil, epoxidized castor oil, epoxidized safflower oil and the like; Epoxidized fatty acid esters obtained by epoxidizing fatty acid alkyl esters; didecyl-4,5-epoxytetrahydrophthalate, diisodecyl-4,5-epoxytetrahydrophthalate, didodecyl-4,5-epoxytetrahydrophthalate, 1,2-epoxycyclohexene, etc. And the like in which the cyclohexene ring of the above is epoxidized. One or more of these epoxidized oils can be used. Among these epoxidized oils, epoxidized oils and fats are preferable, and epoxidized soybean oil and epoxidized linseed oil are preferable.
[0063]
The preferable content of the epoxy compound and the epoxidized oil according to the present invention in the ink is in the range of 10% by mass to 80% by mass, and more preferably in the range of 10% by mass to 50% by mass.
[0064]
《Oxetane compound》
In the present invention, conventionally known oxetane compounds can be used. Examples of the oxetane compounds include known oxetane compounds as disclosed in JP-A-2001-220526 and JP-A-2001-310937. .
[0065]
Examples of the oxetane compound used in the present invention include a compound represented by the following general formula (1).
[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 ink 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 is an integer of 0 to 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 is an integer of 0 to 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 carboxyl 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]
Embedded image

[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]
As an example of the compound having 3 to 4 oxetane rings, Exemplified Compound 3 is given.
[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]
Embedded image

[0094]
In the general formula (9), R⁸Is the R of the general formula (19)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 according to 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 from 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]
《Aprotic polar solvent》
The aprotic polar solvent according to the present invention will be described.
[0100]
Examples of the aprotic polar solvent include dimethylimidazolidinone, N-methylpyrrolidone (NMP), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), sulfolane, , 4-Dimethylsulfolane, sulfolene, quinoline, isoquinoline, 2,6-lutidine, 2,4,6-trimethylpyridine, tetramethylurea, dioxane, tetrahydrofuran (THF), hexamethylphosphoric triamide (HMPA), N- Examples thereof include methylmorpholine (NMm), γ-butyrolactone (BLo), nitromethane, and a compound having a nitrile group.
[0101]
Among them, the above-mentioned compounds having a nitrile group are particularly preferably used. Examples of the compound having a nitrile group include acetonitrile (AcN), butyronitrile, acrylonitrile, and the like.
[0102]
(Amount of aprotic polar solvent used)
The amount of the aprotic polar solvent used is in the range of 0 parts by mass to 20 parts by mass with respect to 100 parts by mass of the total amount of the ink from the viewpoint of preferably exhibiting the effects described in the present invention and preventing color turbidity and the like. Is preferably 0 parts by mass to 10 parts by mass, and particularly preferably 0 parts by mass to 5 parts by mass.
[0103]
《Radical polymerizable monomer》
Various (meth) acrylate monomers can be used as the radical polymerizable monomer according to the present invention. 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- Monofunctional monomers such as butylcyclohexyl 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, bis Bifunctional monomers such as EO adduct diacrylate of enol A, PO adduct diacrylate of bisphenol A, neopentyl glycol diacrylate hydroxypivalate, polytetramethylene glycol diacrylate, trimethylolpropane triacrylate, EO-modified trimethylolpropane Triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin propoxy triacrylate, cowprolactone modified trimethylolpropane triacrylate, pentaerythritol ethoxy tetraacrylate, caprolactam modified dipenta Three officials such as erythritol hexaacrylate Or higher functional monomers.
[0104]
In order to suppress the curing shrinkage of the ink surface when light (also referred to as actinic rays) is irradiated, it is preferable to use a monomer having a curing shrinkage of 10% or less. Above all, monofunctional monomers are preferably used because they have a low shrinkage ratio as compared with difunctional or higher-functional monomers and have flexibility in the ink image so that curling can be suppressed and adhesion to the recording material can be obtained. I can do it.
[0105]
The content of the radical polymerizable monomer according to the present invention in the ink is preferably in the range of 10% by mass to 50% by mass, and more preferably in the range of 10% by mass to 30% by mass.
[0106]
《Photoacid generator》
The photoacid generator used in the present invention will be described.
[0107]
As the photoacid generator, for example, a chemical amplification type photoresist or a compound used for cationic photopolymerization is used (Organic Materials Research Society, "Organic Materials for Imaging", Bunshin Publishing (1993)). -See pages 187-192, Technical Information Association-"Photocuring technology"-Photoacid generator introduced in 2001). Examples of compounds suitable for the present invention are given below. 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. Those having a borate compound as a counter anion are preferable because of high acid generating ability. Specific examples of the onium compound are shown below.
[0108]
Secondly, a sulfonate that generates sulfonic acid can be mentioned. Specific compounds are exemplified below. Third, halides that photogenerate hydrogen halides can also be used. Fourth, an iron allene complex can be mentioned.
[0109]
The compound examples are shown below, but the present invention is not limited thereto.
[0110]
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[0111]
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[0112]
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[0113]
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[0114]
《Photo radical generator》
Examples of the photogenerating agent used in the present invention include arylalkyl ketone, oxime ketone, acylphosphine oxide, acylphosphonate, S-phenyl thiobenzoate, titanocene, aromatic ketone, thioxanthone, benzyl and quinone derivatives or ketocoumarins. Conventionally known ones can be used.
[0115]
Among them, acylphosphine oxides and acylphosphonates are particularly effective for internal curing in ink images having a thickness of 5 μm 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. It is.
[0116]
Specifically, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide and the like are preferable.
[0117]
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.
[0118]
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.
[0119]
《Color material》
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.
[0120]
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,
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.
[0121]
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 parts by mass based on 100 parts by mass of the pigment. The dispersing medium is performed using a solvent or a polymerizable compound. However, in the case of 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 the solvent resistance and VOC 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.
[0122]
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.
[0123]
In the ink according to the present invention, the colorant concentration is preferably 1% by mass to 10% by mass of the whole ink.
[0124]
《Additives etc.》
Various additives other than those described above can be used in the ink according to the present invention. For example, in order to enhance the storage stability of the ink composition, a polymerization inhibitor can be added in an amount of 200 ppm to 20,000 ppm. 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%.
[0125]
As these various monomers and coloring materials, those disclosed in World Patent No. 99/29787 and JP-A-2001-220526 can be used. In addition, these references can be referred to for initiators, additives, and the like.
[0126]
As the photocurable ink according to the present invention, a cationically polymerizable ink and a radically polymerizable ink can each be used alone, but they can also be mixed and used as a hybrid ink. .
[0127]
The ink jet head of the present invention is suitable for these cationically polymerizable and / or radically polymerizable inks, but can exhibit excellent durability especially when a cationically polymerizable ink is used.
[0128]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto.
[0129]
FIG. 1 is a schematic sectional view of an inkjet head according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a piezoelectric ceramic base having grooves cut into three walls of an oil-based ink flow path (see FIG. 2), and 2 denotes one of the ink flow paths bonded to the piezoelectric ceramic base 1. The lid member 5 serving as a wall of the first embodiment is an ink flow path formed by the piezoelectric ceramic base 1 and the lid member 2. The above is the ink chamber of the inkjet head. Reference numeral 10 denotes a cover that covers the entire inkjet head, reference numeral 20 denotes a manifold, reference numeral 25 denotes a filter, reference numeral 30 denotes an ink tube that is adhered to the manifold 20 and supplies ink from an ink storage unit (not shown), and reference numeral 40 denotes FIG. FPC (flexible print circuit) for energizing the electrode film 3 described later, 45 is a drive IC bonded to the FPC 40, 50 is a nozzle plate bonded to the front surface of the ink chamber and having a discharge port for discharging ink droplets, and D is The ejected ink droplet. Arrows in the figure indicate the flow of ink.
[0130]
Oil-based ink from an ink storage unit (not shown) travels along the ink tube 30 to fill the manifold 20. A filter 25 such as a wire net is disposed in the manifold 20 so as to remove foreign matter in the oil-based ink. The oil-based ink filtered by the filter 25 flows into the ink flow path 5. On the other hand, when an image signal is transmitted from the control means of the main body of the ink jet printer (not shown) via the FPC 40, the drive IC 45 generates a voltage for causing the corresponding ink chamber to undergo a shear deformation, and energizes the electrode film 3 described later. I do. Then, the ink chamber that has undergone the shear deformation ejects ink droplets from the ejection openings of the nozzle plate 50.
[0131]
In FIG. 1, the hatched portions (1) to (9) are the bonding portions of the components of the ink jet head. (1) is an adhesive portion between the piezoelectric ceramic substrate 1 and the lid member 2, (2) is an adhesive portion between the ink chamber and the nozzle plate 50, and (3) is an electrode provided on the FPC 40 and the piezoelectric ceramic substrate 1. An adhesive portion between the film 3 (described later), (4) an adhesive portion between the FPC 40 and the driving IC 45, (5) an adhesive portion between the manifold 20 and the piezoelectric ceramic base 1, and (6) a manifold 20 and the cover member 2 7 is an adhesive portion between the manifold 20 and the ink tube 30 in the manifold 20, and 9 is an adhesive portion between the manifold 20 and the ink tube 30. This is a bonding portion for reinforcing bonding to the substrate.
[0132]
The bonded portions (1) and (2) need to be as thin as possible and not protrude into unnecessary portions. This is the part that requires the highest bonding accuracy.
[0133]
It is preferable to use an adhesive having a small expansion and contraction so that the FPC 40 is not peeled off at the bonding portion (3).
[0134]
Since the bonding portion (4) is around the contact point with the drive IC, it is preferable to use a stress-resistant adhesive.
[0135]
It is preferable that the amount of the adhesive in the bonding portion (7) is small so as not to clog the filter.
[0136]
In all of the above-mentioned bonding portions, it is necessary that the bonding process is performed at a low temperature and in a short time so that the piezoelectricity of the piezoelectric ceramic substrate 1 does not disappear, and that the bonding does not flow out of the bonding portion during curing.
[0137]
The color of the bonding portion may be colorless or colored.
FIG. 2 is an enlarged schematic sectional view of the ink chamber shown in FIG. FIG. 2A is a diagram viewed from a cross section perpendicular to the direction of ink flow, and FIG. 2B is a schematic perspective view of a piezoelectric ceramic substrate having an ink flow path formed in a groove shape.
[0138]
In the figure, 1 is a piezoelectric ceramic substrate, 2 is a lid member forming another wall (typically, a lid of an ink flow path formed by bonding a flat plate made of glass, ceramics, metal or plastic), 3 Indicates an electrode film, 4 indicates a protective film, 5 indicates an ink flow path, and (1) indicates an adhesive layer (the same as the adhesive portion (1) in FIG. 1).
[0139]
As the piezoelectric ceramics constituting the piezoelectric ceramic base 1, any conventionally known piezoelectric ceramics can be used, but a ceramic such as PZT, PLZT, etc. is mainly used for softening a mixed microcrystal of PbOx, ZrOx, and TiOx. Alternatively, a material containing a trace amount of a metal oxide known as a hardener, for example, an oxide such as Nb, Zn, Mg, Sn, Ni, La, or Cr is preferable.
[0140]
PZT is a lead zirconate titanate, which is preferable because of its high packing density, large piezoelectric constant, and good workability. When the temperature is lowered after sintering, the crystal structure of PZT suddenly changes, resulting in a collection of fine crystals in the form of a dipole in which atoms are shifted, one side is positive, and the other side is negative. Since such spontaneous polarization has a random direction and the polarities cancel each other, further polarization processing is required.
[0141]
In the polarization treatment, a thin plate of PZT is sandwiched between electrodes, immersed in silicon oil, and polarized by applying a high electric field of about 10 to 35 kV / cm. When a voltage is applied to the polarized PZT in a direction perpendicular to the direction of polarization, the side walls are sheared and deformed in a diagonal direction by a piezoelectric sliding effect, thereby expanding the volume of the ink chamber. In PZT, the piezoelectricity due to this polarization treatment disappears when a temperature higher than 200 ° C. is set and the Curie point is applied.
[0142]
Density of piezoelectric ceramic substrate 1 [g / cm²] Is 8.2, and the density of the lid member 2 [g / cm²] Is 3 or less, but the density of the lid member 2 [g / cm²] Is preferably smaller, for example, not more than half, and the whole ink jet head is lighter, and a compact ink jet head can be obtained.
[0143]
The Young's modulus or elastic modulus [GPa] of the piezoelectric ceramic substrate 1 is 65, and the Young's modulus [GPa] of the cover member 2 is 190 to 390, preferably 200 or more. Can be strongly supported, and the deformation of itself is small, so that efficient driving can be performed and the voltage can be reduced.
[0144]
The coefficient of thermal expansion [ppm / ° C.] of the piezoelectric ceramic substrate 1 is 2 and the coefficient of thermal expansion [ppm / ° C.] of the lid member 2 is 0.6 to 7, but the difference between the two is 5 or less. More preferably, it is 3 or less, and it is possible to prevent warpage due to expansion between the substrates and destruction due to stress due to heat generation during driving and a change in environmental temperature.
[0145]
The thermal conductivity [W / cm · ° C.] of the piezoelectric ceramic substrate 1 is 0.01, and the thermal conductivity [W / cm · ° C.] of the lid member 2 is 0.03 to 0.3. The thermal conductivity [W / cm · ° C.] of the lid member 2 is preferably larger and more preferable, and the heat generated when the piezoelectric ceramic substrate 1 is driven can be released to the outside through the lid member 2.
[0146]
The dielectric constant of the piezoelectric ceramic substrate 1 is 3,000, and the dielectric constant of the lid member 2 is 4.0 to 50. The dielectric constant of the lid member 2 is preferably as small as possible, more preferably 10 or less. Since an electrode pattern for driving the piezoelectric ceramic substrate 1 is provided on the lid member 2 to generate an additional capacitance in addition to the capacitance of the piezoelectric ceramic substrate 1 itself, the capacity of the ink chamber is reduced. Increase the amount of heat generated, and reduce drive efficiency. Therefore, the additional capacitance can be reduced as the dielectric constant of the lid member 2 decreases.
[0147]
The hardness [Hv] of the piezoelectric ceramic substrate 1 is 500, and the dielectric constant of the lid member 2 is 1,000 or more. However, the dielectric constant of the lid member 2 is larger, preferably 1 time or more. Preferably, it is 1.5 times or more, and the yield can be prevented from being deteriorated due to chipping in the manufacturing process.
[0148]
The flexural strength [MPa] of the piezoelectric ceramic substrate 1 is 100, and the flexural strength [MPa] of the lid member 2 is 300 to 900, but is preferably twice or more. The longer the inkjet head is, the more stable the long inkjet head can be manufactured.
[0149]
The volume resistivity [Ω · cm] of the piezoelectric ceramic substrate 1 is 1, and the volume resistivity [Ω · cm] of the lid member 2 is 7 to 10, but is preferably larger than that of the electronic device. In order to reduce the leakage current, the larger the better.
[0150]
The surface roughness Ra of the bonding surface between the lid member 2 and the piezoelectric ceramic substrate 1 is 1.0 μm or less, preferably 0.3 μm or less, more preferably 0.1 μm, and If the surface roughness Ra exceeds 1.0 μm, a large amount of adhesive enters the bonding surface, and the driving force of the piezoelectric ceramic decreases, causing a decrease in sensitivity and an increase in voltage.
[0151]
In addition, the bonding surface between the lid member 2 and the piezoelectric ceramic base 1 is subjected to plasma processing or UV processing. In the plasma processing, the lid member 2 and the piezoelectric ceramic substrate 1 are placed in a vacuum chamber, and Ar, N₂, O₂Is a process of injecting one of the above or a mixed gas to make it into a plasma state by an external electromagnetic field.₄May be used. The UV treatment is a treatment for directly irradiating the lid member 2 and the piezoelectric ceramic substrate 1 with an ultraviolet light emitting lamp.₂May be under atmosphere. By performing the plasma treatment and the UV treatment on the bonding surface in this way, organic contamination can be washed and removed, the wettability of the adhesive on the entire bonding surface can be improved, and bonding defects such as minute bubbles can be eliminated. Thereby, a drive failure of the piezoelectric ceramic substrate 1 can be eliminated, and a stable inkjet head can be manufactured.
[0152]
The piezoelectric ceramic base 1 has, for example, fine grooves (L: 30 mm, H: 360 μm, B: 70 μm) formed on one surface of the base 1 having a thickness of 1 mm. By bonding (adhering) the lid member 2 to the processed surface of the base 1, an ink chamber (L: 30 mm, H: 360 μm, B: 70 μm) serving as an ink flow path is formed in the groove. One end of the ink chamber is connected to an ink storage unit via a manifold including a filter unit, and the other end is connected to an ink discharge port (nozzle plate).
[0153]
The electrode film 3 is formed by a thin film on a fine member (usually about 0.5 to 5.0 μm), and thus is formed by sputtering or the like. However, aluminum, tantalum or the like is preferable in terms of electrical characteristics, corrosion resistance and workability. Or it is preferable to consist of titanium. Further, it is effective to perform anodic oxidation treatment to improve the corrosion resistance and stability of the electrode film. Specific examples of the anodic oxidation treatment are shown below.
[0154]
Piezoelectric ceramic substrate on which an aluminum electrode film having a thickness of 2.0 μm is formed using a solution of pH 7.0 ± 0.5 (adjusted with aqueous ammonia) composed of 300 ml of ethylene glycol and 30 ml of 3% tartaric acid as an electrolytic solution 1 and the current density is 1 mA / cm²Anodization is performed at a constant current until the voltage reaches 100 V, and at a constant voltage of 100 V after the voltage reaches 100 V, and the current density is 0.1 mA / cm.²The process is terminated when the following conditions are satisfied.
[0155]
In the present embodiment, the lid member 2 is bonded to the piezoelectric ceramic base 1 after the anodic oxidation of the electrode film and before the step of forming the protective film 4. In the bonding step, before the adhesive is applied, the processed surface of the piezoelectric ceramic substrate 1 on which the groove is provided and the bonding surface of the lid member 2 covering the groove are subjected to pretreatment such as cleaning and polishing according to the state. Are performed to form the respective bonding surfaces.
[0156]
The bonding surface of the piezoelectric ceramic substrate 1 and the bonding surface of the lid member 2 are bonded with an adhesive, and the piezoelectric ceramic substrate 1 and the lid member 2 are assembled integrally.
[0157]
After assembling the piezoelectric ceramic base 1 and the lid member 2, the bonding surface is heated to a curing temperature of the adhesive in a pressurized state, and the pressurized and heated state is maintained for about 2 hours to cure the adhesive. You. In this bonding step, a bonding layer is formed on the bonding surface, and an ink chamber serving as an ink flow path 5 is formed between the integrated piezoelectric ceramic substrate 1 and the lid member 2.
[0158]
After the bonding step, a protective film 4 as a resin layer is formed on the integrated piezoelectric ceramic substrate 1 and lid member 2 by a CVD method or the like.
[0159]
In the present embodiment, the adhesive used for the bonding portion between the piezoelectric ceramic base 1 and the lid member 2 is an epoxy-based adhesive or a urethane-based adhesive satisfying the following condition 1.
[0160]
<< Condition 1 >>
Viscosity: 30 Pa · s to 500 Pa · s
Curing temperature: 120 ° C or less
Oil absorption ratio: 5% or less
The viscosity is a value determined by a measurement method specified in JIS-K7117, and in the adhesive used in the present invention, preferably 30 Pa · s to 100 Pa · s, more preferably 30 Pa · s to 50 Pa · s. s.
[0161]
The curing temperature is a temperature required to cure the resin (make the molecules three-dimensional) and complete the bonding, and depends on the type and composition of the adhesive. In the adhesive used in the present invention, the curing temperature is preferably 100 ° C or lower.
[0162]
The oil absorption rate is obtained by changing the immersion liquid to oil-based ink in accordance with the water absorption rate measurement method specified in JIS-K7209. Here, the oil-based ink used when measuring the oil absorption rate is most preferably the oil-based ink used by the inkjet head, but any oil-based ink that satisfies the following conditions A and B is used. I do not care.
[0163]
Condition A: A saturated hydrocarbon having 15 to 18 carbon atoms, a unit price alcohol having 15 to 18 carbon atoms, or a derivative thereof is contained as a solvent in an amount of 80% by mass or more.
Condition B: contains a coloring agent
In the adhesive used in the present invention, the oil absorption is preferably 2% or less, more preferably 1% or less.
[0164]
Further, the adhesive used in the present invention is preferably an epoxy-based adhesive or a urethane-based adhesive that further satisfies the following condition 2.
[0165]
<< Condition 2 >>
Thermal expansion coefficient: 100 ppm
The coefficient of thermal expansion refers to a change in length (linear expansion) when the temperature of an object is raised by one degree, and is a value measured by a measurement method specified in JIS-K7197. For example, if the temperature of the adhesive itself rises by one degree and the dimension expands by 0.001 mm per meter, the adhesive has a thermal expansion coefficient of 1 ppm.
[0166]
Naturally, this coefficient of expansion is in the cured adhesive after curing.
In the adhesive used in the present invention, the coefficient of thermal expansion is preferably 85 ppm or less, more preferably 60 ppm or less.
[0167]
As the epoxy adhesive satisfying the above conditions 1 and 2, EP-330, EP-331, 1500, CS2340-5 and the like manufactured by Cemedine are preferably used.
[0168]
Examples of the urethane-based adhesive satisfying the above conditions 1 and 2 include KBK, ERI, 10L, 13, ET60 (epoxy / urethane-based) manufactured by NSC Japan, TE-100, TE-200 manufactured by Sumitomo 3M, and the like. Bond KU 661/662 manufactured by Konishi Co., Ltd., Penguin Cement # 990A manufactured by Sunstar Giken Co., Ltd., Aronmelt R-2030 manufactured by Toagosei Co., Ltd., etc. are preferably used.
[0169]
In the adhesive according to the present invention, an epoxy adhesive is preferably used, and EP-330 and EP-331 manufactured by Cemedine are particularly preferable.
[0170]
Further, when the adhesive according to the present invention is applied to the constituent members of the ink jet head and bonded, the dry film thickness of the adhesive layer is preferably 100 μm or less, and more preferably 10 μm or less.
[0171]
In addition, as a method of applying the adhesive according to the present invention to the constituent members of the inkjet head, a known method can be used. However, in order to accurately control the film thickness, a dispenser method, a screen method, or a roll transfer method is used. The method is preferred.
[0172]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.
[0173]
Example 1
<< Preparation of inkjet heads 1 and 2 >>
Inkjet heads 1 (present invention) and inkjet heads 2 (comparative examples) having the form shown in FIG. 1 were produced using the constituent members shown in Table 1.
[0174]
<< Preparation of inkjet ink >>
A magenta pigment dispersion was prepared as described below, and then a magenta ink (also used as an immersion liquid in an ink immersion test) was prepared using the obtained magenta pigment dispersion.
[0175]
(A) Preparation of magenta pigment dispersion
A magenta pigment dispersion was obtained with the following composition.
[0176]

(B) Preparation of magenta ink
Using the magenta pigment dispersion obtained above, the following formulation was performed, followed by filtration through a 0.8 μm membrane filter, and dehydration under reduced pressure while heating to 50 ° C. to obtain a magenta ink.
[0177]
(Composition of magenta ink)
Magenta pigment dispersion 17 parts by mass
Aron oxetane OXT-221 (Toa Gosei) 70 parts by mass
Celloxide 2021P (DAIcel UCB) @ 30 parts by mass
UVI-6990 (manufactured by Dow Chemical, photoacid generator) 、 5 parts by mass
<< Evaluation of ink immersion of each component of inkjet head >>
For each of the obtained inkjet heads 1 and 2, the above-described ink immersion test was performed using the above-described magenta ink as an immersion liquid, and the mass change rate (%) of each component of the inkjet was determined. The results obtained are shown in Table 1.
[0178]
《Continuous emission test of inkjet head》
A continuous emission test was performed on each of the inkjet heads 1 and 2 as described below.
[0179]
As shown in FIG. 2, the ink jet heads 1 and 2 shown in FIG. 1 are used to bond the piezoelectric ceramic substrate 1 and the lid member 2 using a conventionally known adhesive, and the ink chamber of the ink jet head is formed. 1 and 2 were each produced.
[0180]
Each of the ink jet heads 1 and 2 having the ink chambers 1 and 2 prepared above was mounted on an ink jet printer (PJ5400 manufactured by Olympus Corporation), and the magenta ink (also used for the ink immersion test) was maintained at an ink temperature of 50 ° C. The continuous printing test was performed while performing.
[0181]
The details of the adhesive are as follows.
Main agent: mixture of DGEBA + phenol novolak type epoxy resin
Curing agent: aliphatic polyamine
DGEBA: Bisphenol A diglycidyl ether
Table 1 shows the obtained results.
[0182]
[Table 1]

[0183]
From Table 1, as compared with the comparative inkjet head 2, the inkjet head 1 of the present invention in which the mass change rate of each component of the inkjet head was adjusted to a range of -0.8% to 8.0% by mass. It can be seen that stable emission is possible even in a long continuous emission test of 500 hours.
[0184]
Example 2
<< Preparation of inkjet head 1A >>
An ink-jet head 1A was manufactured in the same manner as in the manufacture of the ink-jet head 1 described in Example 1, except that the curing temperature of the adhesive (main agent + curing agent) was changed from 30 ° C. to 15 ° C.
[0185]
<< Immersion test result and ink sensitivity evaluation when using epoxy adhesive >>
With respect to the ink jet head 1 described in Example 1 and the ink jet head 1A obtained above, the curing sensitivity of the ink was measured for each of the magenta inks 1 and 1A after performing the ink immersion test in the same manner as in Example 1. The effect of an epoxy adhesive, which is one of the components of an ink jet head, on ink curing sensitivity was examined.
[0186]
Regarding the magnitude of the effect on the curing sensitivity, the curing sensitivity of the magenta ink (blank ink) before the ink immersion test was used as an index. The measurement of the curing sensitivity was performed as follows.
[0187]
(Measurement of curing sensitivity)
On a PET (polyethylene terephthalate) film, the ink is adhered to a thickness of 6 μm, a 254 nm fluorescent lamp, and the illuminance on the irradiated surface is 10 mW / cm.²And the amount of energy at which the surface tack disappeared was used as a curing sensitivity index.
[0188]
The results obtained are shown below.

The mass change rate of the epoxy adhesive after the ink immersion test at 30 ° C. was −0.5, and the mass change rate at 15 ° C. was −1.2.
[0189]
From the above results, in the inkjet head 1A using an insufficiently cured adhesive such as the curing condition at 20 ° C., the curing sensitivity (also referred to as ink sensitivity) is lowered. The present inventors presume that this elutes and lowers the ink sensitivity.
[0190]
【The invention's effect】
Advantageous Effects of Invention According to the present invention, an ink jet head and an ink jet recording method are provided, in which the corrosion resistance to a photocurable ink is improved, the clogging of ink nozzles and ink leakage do not occur, the ink droplet ejection accuracy is high, and the influence on ink sensitivity is reduced. Could be provided.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view of an inkjet head according to an embodiment of the present invention.
FIG. 2 is an enlarged schematic diagram of the ink chamber shown in FIG.
[Explanation of symbols]
1) Piezoelectric ceramic substrate
2 Lid member
5 Ink flow path
10 cover
20 mm manifold
25mm filter
30 ink tube
40 FPC
45 ° drive IC
50 nozzle plate
D ink drop
▲ 1 ▼ ～ ▲ 9 ▼ Adhesive part

Claims (7)

An ink jet head of a photocurable ink, wherein when the constituent members constituting the ink jet head are each subjected to an ink immersion test, the mass change rate of the constituent members is -0.8% by mass to 8.0% by mass. % Of the ink jet head. The inkjet head according to claim 1, wherein a mass change rate in the ink immersion test is from -0.2 mass% to 5.0 mass%. The constituent members include PE (polyethylene), polypropylene, PET (polyethylene terephthalate), PBT (polybutylene terephthalate), nylon, TFE (tetrafluoroethylene), PFA (perfluoroalkoxyethylene copolymer), and FEP (fluorinated ethylene). 3. The material according to claim 1, wherein the material is at least one material selected from the group consisting of propylene), perfluoroelastomer, polyparaxylylene, epoxy adhesive, SUS, and PI (polyimide). Ink jet head. At least one of the constituent members is a nozzle plate, the nozzle plate contains at least PI (polyimide), and an impurity ion concentration of the PI (polyimide) is 1.0 ppm or less. Item 4. The inkjet head according to any one of Items 1 to 3. The inkjet head according to any one of claims 1 to 4, wherein the inkjet head is of a shear deformation type that discharges ink by shear deformation of a piezoelectric ceramic. An inkjet recording method using the inkjet head according to claim 1. The ink jet recording method according to claim 6, wherein a cationically polymerizable ink is used as the photocurable ink.

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