JP3969971B2 - INKJET INK, IMAGE RECORDING METHOD, INK CARTRIDGE, RECORDING UNIT, INK SET, FIXING RELAXATION METHOD, IMAGE RECORDING APPARATUS, AND INTERMEDIATE DISCHARGE IMPROVEMENT METHOD - Google Patents

Description

【０１０４】
又、本発明の水性顔料インキは、上記の成分のほかに必要に応じて所望の物性値を持つインクとするために、界面活性剤、消泡剤、防腐剤、防黴剤等を添加することができ、さらに、市販の水溶性染料などを添加することもできる。
【０１０５】
以上のように本発明のインクは、インクジェット記録で用いられる際に特に効果的である。インクジェット記録方法としては、インクに力学的エネルギーを作用させ、液滴を吐出する記録方法、及びインクに熱エネルギーを加えてインクの発砲により液滴を吐出する記録方法があり、それらの記録方法に本発明のインクは特に好適である。
【０１０６】
(インクジェット記録装置、インクジェット記録方法)
インクジェット記録装置として、第一に熱エネルギーを利用した装置の主要部であるヘッド構成例を図１及び図２に示す。
【０１０７】
図１は、インク流路に沿ったヘッド13の断面図であり、図２は図１のＡ-Ｂ線での切断面図である。ヘッド13はインクを通す流路(ノズル)14を有するガラス、セラミック、シリコン又はプラスチック板等と発熱素子基板15とを接着して得られる。発熱素子基板15は酸化シリコン、窒化シリコン、炭化シリコン等で形成される保護層16、アルミニウム、金、アルミニウム-銅合金等で形成される電極17-1、17-2、ＨfＢ₂、ＴaＮ、ＴaＡl等の高融点材料から形成される発熱抵抗体層18、熱酸化シリコン、酸化アルミニウム等で形成される蓄熱層19、シリコン、アルミニウム、窒化アルミニウム等の放熱性の良い材料で形成される基板20より成り立っている。
【０１０８】
上記ヘッドの電極17-1及び17-2にパルス状の電気信号が印加されると、発熱素子基板15のｎで示される領域が急速に発熱し、この表面に接しているインク21に気泡が発生し、その発生する圧力でメニスカス23が突出し、インクがヘッドのノズル14を通して吐出し、吐出オリフィス22よりインク小滴24となり、被記録材25に向かって飛翔する。
【０１０９】
図３には図１に示したヘッドを多数並べたマルチヘッドの外観図を示す。このマルチヘッドはマルチノズル26を有するガラス板27と、図１に説明したものと同じ様な発熱ヘッド28を接着して作られている。
【０１１０】
図４に、このヘッドを組み込んだインクジェット記録装置の一例を示す。図４において、61はワイピング部材としてのブレードであり、その一端はブレード保持部材によって保持固定されており、カンチレバーの形態をなす。ブレード61は記録ヘッド65による記録領域に隣接した位置に配置され、又、本例の場合、記録ヘッド65の移動経路中に突出した形態で保持される。
【０１１１】
62は記録ヘッド65の突出口面のキャップであり、ブレード61に隣接するホームポジションに配置され、記録ヘッド65の移動方向と垂直な方向に移動して、インク吐出口面と当接し、キャッピングを行なう構成を備える。更に、63はブレード61に隣接して設けられるインク吸収体であり、ブレード61と同様、記録ヘッド65の移動経路中に突出した形態で保持される。上記ブレード61、キャップ62及びインク吸収体63によって吐出回復部64が構成され、ブレード61及びインク吸収体63によって吐出口面の水分、塵埃等の除去が行なわれる。
【０１１２】
65は、吐出エネルギー発生手段を有し、吐出口を配した吐出口面に対向する被記録材にインクを吐出して記録を行なう記録ヘッド、66は記録ヘッド65を搭載して記録ヘッド65の移動を行なうためのキャリッジである。キャリッジ66はガイド軸67と摺動可能に系合し、キャリッジ66の一部はモーター68によって駆動されるベルト69と接続(不図示)している。これによりキャリッジ66はガイド軸67に沿った移動が可能となり、記録ヘッド65による記録領域及びその隣接した領域の移動が可能となる。51は被記録材を挿入するための紙給部、52は不図示のモーターにより駆動される紙送りローラーである。
【０１１３】
これらの構成により記録ヘッドの65吐出口面と対向する位置へ被記録材が給紙され、記録の進行に伴って排紙ローラー53を配した排紙部へ排紙される。以上の構成において記録ヘッド65が記録終了してホームポジションへ戻る際、吐出回復部64のキャップ62は記録ヘッド65の移動経路から退避しているが、ブレード61は移動経路中に突出している。その結果、記録ヘッド65の吐出口がワイピングされる。
【０１１４】
尚、キャップ62が記録ヘッド65の吐出面に当接してキャッピングを行なう場合、キャップ62は記録ヘッドの移動経路中に突出するように移動する。記録ヘッド65がホームポジションから記録開始位置へ移動する場合、キャップ62及びブレード61は上記したワイピングの時の位置と同一の位置にある。この結果、この移動においても記録ヘッド65の吐出口面はワイピングされる。
【０１１５】
上述の記録ヘッドのホームポジションへの移動は、記録終了時や吐出回復時ばかりでなく、記録ヘッドが記録のために記録領域を移動する間に所定の間隔で記録領域に隣接したホームポジションへ移動し、この移動に伴って上記ワイピングが行なわれる。
【０１１６】
図５は、記録ヘッドにインク供給部材、例えば、チューブを介して供給されるインクを収容したインクカートリッジ45の一例を示す図である。ここで40は供給用インクを収納したインク収容部、例えば、インク袋であり、その先端にはゴム製の栓42が設けられている。この栓42に針(不図示)を挿入することにより、インク袋40中のインクをヘッドに供給可能にする。44は廃インクを受容するインク吸収体である。インク収容部としてはインクとの接液面がポリオレフィン、特にポリエチレンで形成されているものが好ましい。
【０１１７】
本発明で使用されるインクジェット記録装置としては、上述の様にヘッドとインクカートリッジとが別体となったものに限らず、図６に示すようなそれらが一体になったものにも好適に用いられる。図６において、70は記録ユニットであり、この中にはインクを収容したインク収容部、例えば、インク吸収体が収納されており、かかるインク吸収体中のインクが複数オリフィスを有するヘッド部71からインク滴として吐出される構成になっている。インク吸収体の材料としてはポリウレタンを用いることが本発明にとって好ましい。
【０１１８】
又、インク吸収体を用いず、インク収容部が内部にバネ等を仕込んだインク袋であるような構造でもよい。72はカートリッジ内部を大気に連通させるための大気連通口である。この記録ユニット70は図４に示す記録ヘッド65に換えて用いられるものであって、キャリッジ66に対して着脱自在になっている。
【０１１９】
次に、力学的エネルギーを利用したインクジェット記録装置の形態として、複数のノズルを有するノズル形成基板と、ノズルに対向して配置される圧電材料と導電材料からなる圧力発生素子と、この圧力発生素子の周囲を満たすインクを備え、印加電圧により圧力発生素子を変位させ、インクの小液滴をノズルから吐出させるオンデマンドインクジェット記録ヘッドを挙げることができる。その記録装置の主要部である記録ヘッドの構成例を図７に示す。
【０１２０】
ヘッドは、インク室(不図示)に連通したインク流路80と、所望の体積のインク滴を吐出するためのオリフィスプレート81と、インクに直接圧力を作用させる振動板82と、この振動板82に接合され、電気信号により変位する圧伝素子83と、オリフィスプレート81、振動板等を指示固定するための基板84とから構成されている。
【０１２１】
図７において、インク流路80の壁は、感光性樹脂等で形成され、オリフィスプレート81は、ステンレス、ニッケル等の金属を電鋳やプレス加工による穴あけ等により吐出口85が形成され、振動板82はステンレス、ニッケル、チタン等の金属フィルム及び高弾性樹脂フィルム等で形成され、圧電素子83は、チタン酸バリウム、ＰＺＴ等の誘電体材料で形成される。
【０１２２】
以上のような構成の記録ヘッドは、圧電素子83にパルス状の電圧を与え、ひずみ応力を発生させ、そのエネルギーが圧電素子83に接合された振動板を変形させ、インク流路80内のインクを垂直に加圧しインク滴(不図示)をオリフィスプレートの吐出口85より吐出して記録を行なうように動作する。
【０１２３】
この様な記録ヘッドは図４に示したものと同様な記録装置に組み込んで使用される。記録装置の細部の動作は先述と同様に行なうもので差しつかえない。
【０１２４】
図８(a)〜図８(f)に、本発明の効果を顕著に発揮する記録ヘッドの製造方法の一例を工程順に配列した断面図で示す。勿論、本発明はこの製造方法に基づき製造された記録ヘッドに限定されるものではない。
【０１２５】
まず、例えば図８(a)に示されるような、ガラス、セラミックス、プラスチックあるいは金属等からなる基板１を用意する。
【０１２６】
このような基板１は、液流路構成部材の一部として機能し、また、後述のインク流路およびインク吐出口を形成する材料層の支持体として機能し得るものであれば、その形状、材質等に特に限定されることなく使用できる。上記基板１上には、電気熱変換素子あるいは圧電素子等のインク吐出エネルギー発生素子２が所望の個数配置される。このような、インク吐出エネルギー発生素子２によってインク小滴を吐出させるための吐出エネルギーがインク液に与えられ、記録が行なわれる。
【０１２７】
ちなみに、例えば、上記インク吐出エネルギー発生素子２として電気熱変換素子が用いられる場合には、この素子が近傍の記録液を加熱することにより、記録液に状態変化を生起させ吐出エネルギーを発生する。また、例えば、圧電素子が用いられる場合には、この素子の機械的振動によって、吐出エネルギーを発生する。
【０１２８】
なお、これらの素子２には、これら素子を動作させるための制御信号入力用電極(図示せず)が接続されている。また、一般にはこれら吐出エネルギー発生素子の耐用性の向上を目的として、保護層等の各種機能層が設けられるが、もちろん本発明においてもこのような機能層を設けることは一向に差しつかえない。
【０１２９】
図８(a)において、インク供給のための開口部３を基板１上に予め設けておき、基板１の後方よりインクを供給する形態を例示した。開口部３の形成においては、基板１に穴を形成できる手段であれば、いずれの方法も使用できる。例えば、ドリル等機械的手段で形成しても構わないし、レーザ等の光エネルギーを使用しても構わない。また、基板１にレジストパターン等を形成して化学的にエッチングしても構わない。
【０１３０】
もちろん、インク供給のための開口部３を基板１に形成せず、樹脂パターンに形成し、基板１に対してインク吐出口８と同じ面に設けてもよい。
【０１３１】
次いで、図８(a)に示すように、基板１上に上記インク吐出エネルギー発生素子２を覆うように溶解可能な樹脂でインク流路パターン４を形成する。最も一般的な手段としては感光性材料で形成する手段が挙げられるが、スクリーン印刷法等の手段でも形成は可能である。感光性材料を使用する場合においては、インク流路パターンが溶解可能であるため、ポジ型レジストか、あるいは溶解性変化型のネガ型レジストの使用が可能である。
【０１３２】
レジスト層の形成の方法としては、基板上にインク供給口を設けた基板を使用する場合には、該感光性材料を適当な溶剤に溶解し、ＰＥＴ(ポリエチレンテレフタレート)などのフィルム上に塗布、乾燥してドライフィルムを作成し、ラミネートによって形成することが好ましい。上述のドライフィルムとしては、ポリメチルイソプロピルケトン、ポリビニルケトン等のビニルケトン系光崩壊性高分子化合物を好適に用いることができる。これは、これら化合物が光照射前において高分子化合物としての特性(被膜性)を維持しており、開口部３上にも容易にラミネート可能であるためである。
【０１３３】
また、開口部３に後工程で除去可能な充填物を配置し通常のスピンコート法、ロールコート法等で被膜を形成しても構わない。
【０１３４】
このようにインク流路をパターニングした溶解可能な樹脂材料層４上に、図８(b)に示すように、さらに被覆樹脂層５を通常のスピンコート法、ロールコート法等で形成する。ここで、被覆樹脂層５を形成する工程において、溶解可能な樹脂パターンを変形せしめない等の特性が必要となる。すなわち、被覆樹脂層５を溶剤に溶解し、これをスピンコート、ロールコート等で溶解可能な樹脂パターン４上に形成する場合、溶解可能な樹脂パターン４を溶解しないように溶剤を選択する必要がある。
【０１３５】
ここで、被覆樹脂層５について説明する。被覆樹脂層５としては、後述のインク吐出口をフォトリソグラフィで容易にかつ精度よく形成できることから、感光性のものが好ましい。このような感光性被覆樹脂層５は、構造材料としての高い機械的強度、基板１との密着性、耐インク性と、同時にインク吐出口の微細なパターンをパターニングするための解像性が要求される。ここで、エポキシ樹脂のカチオン重合硬化物が構造材料として優れた強度、密着性、対インク性を有し、かつ前記エポキシ樹脂が常温で固体状であれば、優れたパターニング特性を有することが見いだされている。
【０１３６】
まず、エポキシ樹脂のカチオン重合硬化物は、通常の酸無水物もしくはアミンによる硬化物に比較して高い架橋密度(高Ｔg)を有するため、構造材として優れた特性を示す。また、常温で固体状のエポキシ樹脂を用いることで、光照射によりカチオン重合開始剤より発生した重合開始種のエポキシ樹脂中への拡散が抑えられ、優れたパターニング精度、形状を得ることができる。
【０１３７】
溶解可能な樹脂層上に被覆樹脂層を形成する工程は、常温で固体状の被覆樹脂を溶剤に溶解し、スピンコート法で形成することが望ましい。
【０１３８】
薄膜コーティング技術であるスピンコート法を用いることで、被覆樹脂層５は均一にかつ精度良く形成することができ、従来方法では困難であったインク吐出エネルギー発生素子２とオリフィス間の距離(ＯＨ距離)を短くすることができ、小液滴吐出を容易に達成することができる。
【０１３９】
また、被覆樹脂として上述のいわゆるネガ型の感光性材料を用いた場合、通常は基板面からの反射、およびスカム(現像残渣)が発生する。しかしながら、本発明の場合、溶解可能な樹脂で形成されたインク流路上に吐出口パターンを形成するため、基板からの反射の影響は無視でき、さらに現像時に発生するスカムは、後述のインク流路を形成する溶解可能な樹脂を洗い出す工程でリフトオフされるため、悪影響を及ぼさない。
【０１４０】
本発明に用いる固体状のエポキシ樹脂としては、ビスフェノールＡとエピクロヒドリンとの反応物のうち分子量がおよそ900以上のもの、含ブロモスフェノールＡとエピクロヒドリンとの反応物、フェノールノボラックあるいはo-クレゾールノボラックとエピクロヒドリンとの反応物、特開昭60-161973号公報、特開昭63-221121号公報、特開昭64-9216号公報、特開平２-140219号公報に記載のオキシシクロヘキサン骨格を有する多感応エポキシ樹脂等があげられるが、もちろん本発明はこれら化合物に限定されるわけではない。
【０１４１】
上記エポキシ樹脂を硬化させるための光カチオン重合開始剤としては、芳香族ヨードニウム塩、芳香族スルホニウム塩[Ｊ.ＰＯＬＹＭＥＲ ＳＣＩ:Ｓyｍposiuｍ Ｎo.56, 383-395 (1976)参照]や旭電化工業株式会社より上市されているＳＰ-150、ＳＰ-170等が挙げられる。
【０１４２】
また、上述の光カチオン重合開始剤は、還元剤を併用し加熱することによって、カチオン重合を促進(単独の光カチオン重合に比較して架橋密度が向上する。)させることができる。ただし、光カチオン重合開始剤と還元剤を併用する場合、常温では反応せず一定温度以上(好ましくは60℃以上)で反応するいわゆるレドックス型の開始剤系になるように、還元剤を選択する必要がある。
【０１４３】
このような還元剤としては、銅化合物、特に反応性とエポキシ樹脂への溶解性を考慮して銅トリフラート(トリフルオロメタンスルフォン酸銅(II))が最適である。また、アスコルビン酸等の還元剤も有用である。また、ノズル数の増加(高速印刷性)、非中性インクの使用(着色剤の耐水性の改良)等、より高い架橋密度(高Ｔg)が必要な場合は、上述の還元剤を後述のように前記被覆樹脂層の現像工程後に溶液の形で用いて被覆樹脂層を浸漬および加熱する後工程によって、架橋密度を上げることができる。
【０１４４】
さらに上記組成物に対して必要に応じて添加剤など適宜添加することが可能である。例えば、エポキシ樹脂の弾性率を下げる目的で可撓性付与剤を添加したり、あるいは基板との更なる密着力を得るためにシランカップリング剤を添加することなどがあげられる。
【０１４５】
次いで、上記化合物からなる感光性被覆樹脂層５に対して、図８(c)に示すように、マスク６を介してパターン露光を行なう。感光性被覆樹脂層５は、ネガ型であり、インク吐出口を形成する部分をマスクで遮蔽する。(むろん、電気的な接続を行なう部分も遮蔽する。図示せず)。
【０１４６】
パターン露光は、使用する光カチオン重合開始剤の感光領域に合わせて紫外線、Ｄeep-ＵＶ光、電子線、Ｘ線などから適宜選択することができる。
【０１４７】
ここで、これまでの工程は、すべて従来のフォトリソグラフィ技術を用いて位置合わせが可能であり、オリフィスプレートを別途作成し基板と張り合わせる方法に比べて、格段に精度を上げることができる。こうしてパターン露光された感光性被覆樹脂層５は、必要に応じて反応を促進するために、加熱処理を行なってもよい。ここで、前述のごとく、感光性被覆樹脂層は常温で固体状のエポキシ樹脂で構成されているため、パターン露光で生じるカチオン重合開始種の拡散は制約を受け、優れたパターニング精度、形状を実現できる。
【０１４８】
次いで、パターン露光された感光性被覆樹脂層５は、適当な溶剤を用いて現像され、図８(d)に示すように、インク吐出口８を形成する。ここで、未露光の感光性被覆樹脂層の現像時に同時にインク流路を形成する溶解可能な樹脂パターン４を現像することも可能である。
【０１４９】
ただし、一般的に、基板１上には複数の同一または異なる形態のヘッドが配置され、切断工程を経てインクジェット液体吐出ヘッドとして使用されるため、切断時のごみ対策として、図８(d)に示すように感光性被覆樹脂層５のみを選択的に現像することにより、インク流路９を形成する樹脂パターン４を残し(液室内に樹脂パターン４が残存するため切断時に発生するゴミが入り込まない)、切断工程後に樹脂パターン４を現像することも可能である(図８(e)参照)。また、この際、感光性被覆樹脂層５を現像する時に発生するスカム(現像残渣)は、溶解可能な樹脂層４と共に溶出されるためノズル内には残渣が残らない。
【０１５０】
前述したように架橋密度を上げる必要がある場合には、この後、インク流路９およびインク吐出口８が形成された感光性被覆樹脂層５を還元剤を含有する溶液に浸漬および加熱することにより後硬化を行なう。これにより、感光性被覆樹脂層５の架橋密度はさらに高まり、基板に対する密着性および耐インク性は非常に良好となる。
【０１５１】
もちろん、この銅イオン含有溶液に浸漬加熱する工程は、感光性被覆樹脂層５をパターン露光し、現像してインク吐出口８を形成した直後に行なっても一向にさしつかえなく、その後で溶解可能な樹脂パターン４を溶出しても構わない。また浸漬、加熱工程は、浸漬しつつ加熱しても構わないし、浸漬後に加熱処理を行なっても構わない。
【０１５２】
このような還元剤としては、還元作用を有する物質であれば有用であるが、特に銅トリフラート、酢酸銅、安息香酸銅など銅イオンを含有する化合物が有効である。前記化合物の中でも、特に銅トリフラートは非常に高い効果を示す。さらに前記以外にアスコルビン酸も有用である。
【０１５３】
このようにして形成したインク流路およびインク吐出口を形成した基板に対して、インク供給のための部材７およびインク吐出圧力発生素子２を駆動するための電気的接合(図示せず)を行なってインクジェット液体吐出ヘッドが形成される(図８(f)参照)。
【０１５４】
尚、本製造例では、インク吐出口８の形成をフォトリソグラフィによって行なったが、本発明はこれに限ることなく、マスクを変えることによって、酸素プラズマによるドライエッチングやエキシマレーザによってもインク吐出口８を形成することができる。エキシマレーザやドライエッチングによってインク吐出口８を形成する場合には、基板が樹脂パターンで保護されてレーザやプラズマによって傷つくことがないため、精度と信頼性の高いヘッドを提供することも可能となる。さらに、ドライエッチングやエキシマレーザ等でインク吐出口８を形成する場合は、被覆樹脂層５は感光性のもの以外にも熱硬化性のものも適用可能である。
【０１５５】
次に本発明に好適に使用できる記録装置および記録ヘッドの他の具体例を説明する。図９は、本発明に係る吐出時に気泡を大気と連通する吐出方式の液体吐出ヘッドとしての液体吐出ヘッドおよびこのヘッドを用いる液体吐出装置としてのインクジェットプリンタの一例の要部を示す概略斜視図である。
【０１５６】
図９においては、インクジェットプリンタは、ケーシング1008内に長手方向に沿って設けられる記録媒体としての用紙1028を図９に示す矢印Ｐで示す方向に間欠的に搬送する搬送装置1030と、搬送装置1030による用紙1028の搬送方向Ｐに略直交する方向Ｓに略平行に往復運動せしめられる記録部1010と、記録部1010を往復運動させる駆動手段としての移動駆動部1006とを含んで構成されている。
【０１５７】
移動駆動部1006は、所定の間隔をもって対向配置される回転軸に配されるプーリ1026aおよび1026bに巻きかけられるベルト1016と、ローラユニット1022aおよび1022bに略平行に配置され記録部1010のキャリッジ部材1010aに連結されるベルト1016を順方向および逆方向に駆動させるモータ1018とを含んで構成されている。
【０１５８】
モータ1018が作動状態とされてベルト1016が図９の矢印Ｒ方向に回転したとき、記録部1010のキャリッジ部材1010aは図９の矢印Ｓ方向に所定の移動量だけ移動される。また、モータ1018が作動状態とされてベルト1016が図９の矢印Ｒ方向とは逆方向に回転したとき、記録部1010のキャリッジ部材1010aは図９の矢印Ｓ方向とは反対の方向に所定の移動量だけ移動されることとなる。さらに、移動駆動部1006の一端部には、キャリッジ部材1010aのホームポジションとなる位置に、記録部1010の吐出回復処理を行なうための回復ユニット1026が記録部1010のインク吐出口配列に対向して設けられている。
【０１５９】
記録部1010は、インクジェットカートリッジ(以下、単にカートリッジと記述する場合がある)1012Ｙ、1012Ｍ、1012Ｃおよび1012Ｂが各色、例えばイエロー、マゼンタ、シアンおよびブラックごとにそれぞれ、キャリッジ部材1010aに対して着脱自在に備えられる。
【０１６０】
図10は上述のインクジェット記録装置に搭載可能なインクジェットカートリッジの一例を示す。本例におけるカートリッジ1012は、シリアルタイプのものであり、インクジェット記録ヘッド100と、インクなどの液体を収容する液体タンク1001とで主要部が構成されている。
【０１６１】
インクジェット記録ヘッド100は液体を吐出するための多数の吐出口832が形成されており、インクなどの液体は、液体タンク1001から図示しない液体供給通路を介して液体吐出ヘッド100の共通液室(図11参照)へと導かれるようになっている。カートリッジ1012は、インクジェット記録ヘッド100と液体タンク1001とを一体的に形成し、必要に応じて液体タンク1001内に液体を補給できるようにしたものであるが、この液体吐出ヘッド100に対し、液体タンク1001を交換可能に連結した構造を採用するようにしてもよい。
【０１６２】
このような構成のインクジェットプリンタに搭載され得る上述の液体吐出ヘッドの具体例を以下にさらに詳しく説明する。
【０１６３】
図11は本発明の基本的な形態を示す液体吐出ヘッドの要部を模式的に示す概略斜視図であり、図12〜図15は図11に示した液体吐出ヘッドの吐出口形状を示す正面図である。なお、電気熱変換素子を駆動するための電気的な配線などは省略している。
【０１６４】
本例の液体吐出ヘッドにおいては、例えば図11に示されるような、ガラス、セラミックス、プラスチックあるいは金属などからなる基板934が用いられる。このような基板の材質は、本発明の本質ではなく、流路構成部材の一部として機能し、インク吐出エネルギー発生素子、および後述する液流路、吐出口を形成する材料層の支持体として、機能し得るものであれば、特に限定されるものではない。そこで、本例では、Ｓi基板(ウエハ)を用いた場合で説明する。吐出口は、レーザー光による形成方法の他、例えば後述するオリフィスプレート(吐出口プレート)935を感光性樹脂として、ＭＰＡ(Ｍirror Ｐrojection Ａliner)などの露光装置により形成することもできる。
【０１６５】
図11において934は電気熱変換素子(以下、ヒータと記述する場合がある)931および共通液室部としての長溝状の貫通口からなるインク供給口933を備える基板であり、インク供給口933の長手方向の両側に熱エネルギー発生手段であるヒータ931がそれぞれ１列ずつ千鳥状に電気熱変換素子の間隔が、例えば300dpiで配列されている。この基板934上にはインク流路を形成するためのインク流路壁936が設けられている。このインク流路壁936には、さらに吐出口832を備える吐出口プレート935が設けられている。
【０１６６】
ここで、図11においてはインク流路壁936と吐出口プレート935とは、別部材として示されているが、このインク流路壁936を例えばスピンコートなどの手法によって基板934上に形成することによりインク流路壁936と吐出口プレート935とを同一部材として同時に形成することも可能である。本例では、さらに、吐出口面(上面)935a側は撥水処理が施されている。
【０１６７】
本例では、図９の矢印Ｓ方向に走査しながら記録を行なうシリアルタイプのヘッドを用い、例えば、1200dpiで記録を行なう。駆動周波数は10kＨzであり、一つの吐出口では最短時間間隔100μsごとに吐出を行なうことになる。
【０１６８】
また、ヘッドの実例寸法の一例としては、例えば、図12に示すように、隣接するノズルを流体的に隔離する隔壁936aは、幅ｗ＝14μｍである。図15に示すように、インク流路壁936により形成される発泡室1337は、Ｎ₁(発泡室の幅寸法)＝33μｍ,Ｎ₂(発泡室の長さ寸法)＝35μｍである。ヒータ931のサイズは30μｍ×30μｍでヒータ抵抗値は53Ωであり、駆動電圧は10.3Ｖである。また、インク流路壁936および隔壁936aの高さは12μｍで、吐出口プレート厚は11μｍのものが使用できる。
【０１６９】
吐出口832を含む吐出口プレートに設けられた吐出口部940の断面のうち、インクの吐出方向(オリフィスプレート935の厚み方向)に交差する方向で切断してみた断面の形状は概略星形となっており、鈍角の角を有する６つの起部832aと、これら起部832aの間に交互に配されかつ鋭角の角を有する６つの伏部832bとから概略構成されている。すなわち、吐出口の中心Ｏから局所的に離れた領域としての伏部832bをその頂部、この領域に隣接する吐出口の中心Ｏから局所的に近い領域としての起部832aをその基部として、図11に示すオリフィスプレートの厚み方向(液体の吐出方向)に６つの溝が形成されている(溝部の位置については図16の1141a参照)。
【０１７０】
本例においては、吐出口部940は、例えばその厚み方向に交差する方向で切断した断面が一辺27μｍの二つの正三角形を60度回転させた状態で組み合わせた形状となっており、図13に示すＴ₁は８μｍである。起部832aの角度はすべて120度であり、伏部832bの角度はすべて60度である。
【０１７１】
従って、吐出口の中心Ｏと、互いに隣接する溝の中心部(溝の頂部と、この頂部に隣接する２つの基部とを結んでできる図形の中心(重心))を結んで形成される多角形の重心Ｇとが一致するようになっている。本例の吐出口832の開口面積は400μｍ²であり、溝部の開口面積(溝の頂部と、この頂部に隣接する２つの基部とを結んでできる図形の面積)は１つあたり約33μｍ²となっている。
【０１７２】
図14は図13に示した吐出口の部分のインク付着状態を示す模式図であり、Ｃはインク付着部を表わしている。
【０１７３】
次に、上述の構成のインクジェット記録ヘッドによる液体の吐出動作について図16〜図23を用いて説明する。
【０１７４】
図16〜図23は、図11〜図15に記載の液体吐出ヘッドの液体吐出動作を説明するための断面図であり、図15に示す発泡室1337のＸ-Ｘ断面図である。この断面において吐出口部940のオリフィスプレート厚み方向の端部は、溝1141の頂部1141aとなっている。
【０１７５】
図16はヒータ上に膜状の気泡が生成した状態を示し、図17は図16の約１μs後、図18は図16の約２μs後、図19は図16の約３μs後、図20は図16の約４μs後、図21は図16の約５μs後、図22は図16の約６μs後、図23は図16の約７μs後の状態をそれぞれ示している。なお、以下の説明において、「落下」または「落とし込み」、「落ち込み」とは、いわゆる重力方向への落下という意味ではなく、ヘッドの取り付け方向によらず、電気熱変換素子の方向への移動をいう。
【０１７６】
まず、図16に示すように、記録信号などに基づいたヒータ931への通電に伴いヒータ931上の液流路1338内に気泡101が生成されると、約２μs間に図17および図18に示すように急激に体積膨張して成長する。気泡101の最大体積時における高さは吐出口面935a上回るが、このとき、気泡の圧力は大気圧の数分の１から10数分の１にまで減少している。
【０１７７】
次に、気泡101の生成から約２μs後の時点で気泡101は上述のように最大体積から体積減少に転じるが、これとほぼ同時にメニスカス102の形成も始まる。このメニスカス102も図19に示すようにヒータ931側への方向に後退、すなわち落下してゆく。
【０１７８】
ここで、本例においては、吐出口部に複数の溝1141を分散させて有していることにより、メニスカス102が後退する際に、溝1141の部分ではメニスカス後退方向Ｆ_Mとは反対方向Ｆ_Cに毛管力が作用する。その結果、仮に何らかの原因により気泡101の状態に多少のバラツキが認められたとしても、メニスカスの後退時のメニスカスおよび主液滴(以下、液体またはインクと記述する場合がある)Iaの形状が、吐出口中心に対して略対称形状となるように補正される。
【０１７９】
そして、本例では、このメニスカス102の落下速度が気泡101の収縮速度よりも速いために、図20に示すように気泡の生成から約４μs後の時点で気泡101が吐出口832の下面近傍で大気に連通する。このとき、吐出口832の中心軸近傍の液体(インク)はヒータ931に向かって落ち込んでゆく。これは、大気に連通する前の気泡101の負圧によってヒータ931側に引き戻された液体(インク)Iaが、気泡101の大気連通後も慣性でヒータ931面方向の速度を保持しているからである。
【０１８０】
ヒータ931側に向かって落ち込んでいった液体(インク)は、図21に示すように気泡101の生成から約５μs後の時点でヒータ931の表面に到達し、図22に示すようにヒータ931の表面を覆うように拡がってゆく。このようにヒータ931の表面を覆うように拡がった液体はヒータ931の表面に沿った水平方向のベクトルを有するが、ヒータ931の表面に交差する、例えば垂直方向のベクトルは消滅し、ヒータ931の表面上に留まろうとし、それよりも上側の液体、すなわち吐出方向の速度ベクトルを保つ液体を下方向に引っ張ることになる。
【０１８１】
その後、ヒータ931の表面に拡がった液体と上側の液体(主液滴)との間の液体部分Ibが細くなってゆき、気泡101の生成から約７μs後の時点で図23に示すようにヒータ１の表面の中央で液体部分Ibが切断され、吐出方向の速度ベクトルを保つ主液滴Iaとヒータ931の表面上に拡がった液体Icとに分離される。このように分離の位置は液流路1338内部、より好ましくは吐出口832よりも電気熱変換素子931側が望ましい。
【０１８２】
主液滴Iaは吐出方向に偏りがなく、吐出ヨレすることなく、吐出口832の中央部分から吐出され、記録媒体の被記録面の所定位置に着弾される。また、ヒータ931の表面上に拡がった液体Icは、従来であれば主液滴の後続としてサテライト滴となって飛翔するものであるが、ヒータ931の表面上に留まり、吐出されない。
【０１８３】
このようにサテライト滴の吐出を抑制することができるため、サテライト滴の吐出により発生し易いスプラッシュを防止することができ、霧状に浮遊するミストにより記録媒体の被記録面が汚れるのを確実に防止することができる。なお図20〜23において、Idは溝部に付着したインク(溝内のインク)を、またIeは液流路内に残存しているインクを表している。
【０１８４】
このように、本例の液体吐出ヘッドでは、気泡が最大体積に成長した後の体積減少段階で液体を吐出する際に、吐出口の中心に対して分散した複数の溝により、吐出時の主液滴の方向を安定化させることができる。その結果、吐出方向のヨレのない、着弾精度の高い液体吐出ヘッドを提供することができる。また、高い駆動周波数での発泡ばらつきに対しても吐出を安定して行なうことができることによる、高速高精細印字を実現することができる。
【０１８５】
特に、気泡の体積減少段階でこの気泡を始めて大気と連通させることで液体を吐出することにより、気泡を大気に連通させて液滴を吐出する際に発生するミストを防止できるので、所謂、突然不吐の要因となる、吐出口面に液滴が付着する状態を抑制することもできる。
【０１８６】
また本発明に好適に使用できる、吐出時に気泡を大気と連通する吐出方式の記録ヘッドの他の実施態様として、例えば日本特許登録第2783647号公報に記載のように、いわゆるエッジシュータータイプが挙げられる。
【０１８７】
本発明は、特にインクジェット記録方式の中でも熱エネルギーを利用して飛翔的液滴を形成し、記録を行なうインクジェット方式の記録ヘッド、記録装置において、優れた効果をもたらすものである。
【０１８８】
その代表的な構成や原理については、例えば、米国特許第4723129号明細書、同第4740796号明細書に開示されている基本的な原理を用いて行なうものが好ましい。この方式はいわゆるオンデマンド型、コンティニュアス型のいずれにも適用可能であるが、特に、オンデマンド型の場合には、液体(インク)が保持されているシートや液路に対応して配置されている電気熱変換体に、記録情報に対応していて核沸騰を越える急速な温度上昇を与える少なくとも一つの駆動信号を印加することによって、電気熱変換体に熱エネルギーを発生せしめ、記録ヘッドの熱作用面に膜沸騰を生じさせて、結果的にこの駆動信号に一対一で対応した液体(インク)内の気泡を形成できるので有効である。この気泡の成長、収縮により吐出用開口を介して液体(インク)を吐出させて、少なくとも一つの滴を形成する。この駆動信号をパルス形状とすると、即時適切に気泡の成長収縮が行なわれるので、特に応答性に優れた液体(インク)の吐出が達成でき、より好ましい。
【０１８９】
このパルス形状の駆動信号としては、米国特許第4463359号明細書、同第4345262号明細書に記載されているようなものが適している。なお、上記熱作用面の温度上昇率に関する発明の米国特許第4313124号明細書に記載されている条件を採用すると、更に優れた記録を行なうことができる。
【０１９０】
記録ヘッドの構成としては、上述の各明細書に開示されているような吐出口、液路、電気熱変換体の組み合わせ構成(直線状液流路または直角液流路)の他に、熱作用部が屈曲する領域に配置されている構成を開示する米国特許第4558333号明細書、米国特許第4459600号明細書を用いた構成も本発明に含まれるものである。
【０１９１】
加えて、複数の電気熱変換体に対して、共通するスリットを電気熱変換体の吐出部とする構成を開示する特開昭59-123670号公報や熱エネルギーの圧力波を吸収する開孔を吐出部に対応させる構成を開示する特開昭59-138461号公報に基づいた構成としても本発明は有効である。
【０１９２】
さらに、記録装置が記録できる最大記録媒体の幅に対応した長さを有するフルラインタイプの記録ヘッドとしては、上述した明細書に開示されているような複数記録ヘッドの組み合わせによってその長さを満たす構成や、一体的に形成された１個の記録ヘッドとしての構成のいずれでもよいが、本発明は、上述した効果を一層有効に発揮することができる。
【０１９３】
加えて、装置本体に装着されることで、装置本体との電気的な接続や装置本体からのインクの供給が可能になる交換自在のチップタイプの記録ヘッド、あるいは記録ヘッド自体に一体的にインクタンクが設けられたカートリッジタイプの記録ヘッドを用いた場合にも本発明は有効である。
【０１９４】
また、本発明の記録装置の構成として設けられる、記録ヘッドに対しての回復手段、予備的な補助手段等を付加することは本発明の効果を一層安定できるので好ましいものである。これらを具体的に挙げれば、記録ヘッドに対してのキャッピング手段、クリーニング手段、加圧あるいは吸引手段、電気熱変換体あるいはこれとは別の加熱素子あるいはこれらの組み合わせによる予備加熱手段、記録とは別の吐出を行なう予備吐出モードを行なうことも安定した記録を行なうために有効である。
【０１９５】
さらに、記録装置の記録モードとしては黒色等の主流色のみの記録モードだけではなく、記録ヘッドを一体的に構成するか複数個の組み合わせによってでもよいが、異なる色の複色カラー、または混色によるフルカラーの少なくとも一つを備えた装置にも本発明は極めて有効である。
【０１９６】
以上説明した本発明の実施例においては、インクを液体として説明しているが、室温やそれ以下で固化するインクであって、室温で軟化するもの、もしくは液体であるもの、あるいは上述のインクジェット方式ではインク自体を30℃以上70℃以下の範囲内で温度調整を行なってインクの粘性を安定吐出範囲にあるように温度制御するものが一般的であるから、使用記録信号付与時にインクが液状をなすものであれば良い。
【０１９７】
加えて、積極的に熱エネルギーによる昇温をインクの固形状態から液体状態への状態変化のエネルギーとして使用せしめることで防止するか、またはインクの蒸発防止を目的として放置状態で固化するインクを用いるかして、いずれにしても熱エネルギーの記録信号に応じた付与によってインクが液化し、液状インクとして吐出するものや、記録媒体に到達する時点では既に固化し始めるもの等のような、熱エネルギーによって初めて液化する性質のインクの使用も本発明には適用可能である。このような場合インクは、特開昭54-56847号公報あるいは特開昭60-71260号公報に記載されるような、多孔質シート凹部または貫通孔に液状または固形物として保持された状態で、電気熱変換体に対して対向するような形態としても良い。本発明においては、上述した各インクに対して最も有効なものは、上述した膜沸騰方式を実行するものである。
【０１９８】
さらに加えて、本発明に係る記録装置の形態としては、ワードプロセッサやコンピュータ等の情報処理機器の画像出力端末として一体または別体に設けられるものの他、リーダと組み合せた複写装置、さらには送受信機能を有するファクシミリ装置の形態を採るものであってもよい。
【０１９９】
次に、上述した液体吐出ヘッドを搭載する液体吐出装置の概略について説明する。
【０２００】
図29は、本発明の液体吐出ヘッドを装着して適用することのできる液体吐出装置の一例であるインクジェット記録装置600の概略斜視図である。
【０２０１】
図29において、インクジェットヘッドカートリッジ601は、上述した液体吐出ヘッドとこの液体吐出ヘッドに供給するインクを保持するインクタンクとが一体となったものである。このインクジェットヘッドカートリッジ601は、駆動モータ602の正逆回転に連動して駆動力伝達ギア603、604を介して回転するリードスクリュ605の螺旋溝606に対して係合するキャリッジ607上に搭載されており、駆動モータ602の動力によってキャリッジ607とともにガイド608に沿って矢印a,b方向に往復移動される。被記録材Ｐ'は、図示しない被記録材搬送手段によってプラテンローラ609上を搬送され、紙押え板610によりキャリッジ607の移動方向にわたってプラテンローラ609に対して押圧される。
【０２０２】
リードスクリュ605の一端の近傍には、フォトカプラ611、612が配設されている。これらはキャリッジ607のレバー607aのこの域での存在を確認して駆動モータ602の回転方向切り換え等を行なうためのホームポジション検知手段である。
【０２０３】
支持部材613は、上述のインクジェットヘッドカートリッジ601の吐出口のある前面(吐出口面)を覆うキャップ部材614を支持するものである。また、インク吸引手段615は、キャップ部材614の内部にインクジェットヘッドカートリッジ601から空吐出等されて溜まったインクを吸引するものである。このインク吸引手段615によりキャップ内開口部(不図示)を介してインクジェットヘッドカートリッジ601の吸引回復が行なわれる。インクジェットヘッドカートリッジ601の吐出口面を払拭するためのクリーニングブレード617は、移動部材618により前後方向(上記キャリッジ607の移動方向に直交する方向)に移動可能に設けられている。これらクリーニングブレード617及び移動部材618は、本体支持体619に支持されている。クリーニングブレード617は、この形態に限らず、他の周知のクリーニングブレードであってもよい。
【０２０４】
液体吐出ヘッドの吸引回復操作にあたって、吸引を開始させるためのレバー620は、キャリッジ607と係合するカム621の移動に伴って移動し、駆動モータ602からの駆動力がクラッチ切り換え等の公知の伝達手段で移動制御される。インクジェットヘッドカートリッジ601の液体吐出ヘッドに設けられた発熱体に信号を付与したり、前述した各機構の駆動制御を司ったりするインクジェット記録制御部は装置本体側に設けられており、ここには図示しない。
【０２０５】
上述の構成を有するインクジェット記録装置600は、図示しない被記録材搬送手段によりプラテンローラ609上を搬送される被記録材Ｐ'に対し、インクジェットヘッドカートリッジ601は被記録材Ｐ'の全幅にわたって往復移動しながら記録を行なう。
【０２０６】
【実施例】
以下、実施例および比較例を用いてさらに具体的に説明するが、本発明は、その要旨を越えない限り、下記実施例により限定されるものではない。尚以下の記載で、「部」、「％」とあるものは特に断らない限り質量基準である。
【０２０７】
(顔料分散液の調製)
〔顔料分散液Ａ〕
5.3gの水に５gの濃塩酸をとかした溶液に５℃においてアントラニル酸1.58gを加えた。これに、アイスバスで攪拌することにより常に10℃以下に保たれた状態で、５℃の8.7gの水に1.78gの亜硝酸ナトリウムを加えた溶液を加えた。
【０２０８】
これに更に、15分攪拌後、表面積が220ｍ²/gでＤＢＰ吸油量が105ｍL/100gのカーボンブラック７gを混合した状態のまま加えた。その後、さらに15分攪拌した。得られたスラリーを東洋濾紙Ｎo.２(アドバンティス社製)で濾過し、顔料粒子を十分に水洗し、110℃のオーブンで乾燥させ、さらに、この顔料に水を足して顔料濃度10質量％の顔料水溶液を作製した。
【０２０９】
尚、上記で作製した自己分散型カーボンブラックの親水性基密度を下記のようにして測定したところ、2.6μｍol/ｍ²であった。測定方法としては、イオンメーター(ＤＫＫ製)を用いナトリウムイオン濃度を測定し、その値から親水性基密度を換算した。そしてイオン交換法を用いてナトリウムイオンをアンモニウムイオンに置換することによって、カーボンブラックの表面に-Ｐh-ＣＯＯＮＨ₄基を導入した自己分散型カーボンブラックが分散された顔料分散液Ａを得た。
【０２１０】
〔顔料分散液Ｂ〕
5.3gの水に５gの濃塩酸をとかした溶液に５℃においてアントラニル酸1.58gを加えた。これに、アイスバスで攪拌することにより常に10℃以下に保たれた状態で、５℃の8.7gの水に1.78gの亜硝酸ナトリウムを加えた溶液を加えた。
【０２１１】
これに更に、15分攪拌後、表面積が220ｍ²/gでＤＢＰ吸油量が105ｍL/100gのカーボンブラック８gを混合した状態のまま加えた。その後、さらに15分攪拌した。得られたスラリーを東洋濾紙Ｎo.２(アドバンティス社製)で濾過し、顔料粒子を十分に水洗し、110℃のオーブンで乾燥させ、さらに、この顔料に水を足して顔料濃度10質量％の顔料水溶液を作製した。
【０２１２】
尚、上記で作製した自己分散型カーボンブラックの親水性基密度を上記と同様に測定したところ、1.6μｍol/ｍ²であった。そしてイオン交換法を用いてナトリウムイオンをアンモニウムイオンに置換することによって、カーボンブラックの表面に-Ｐh-ＣＯＯＮＨ₄基を導入した自己分散型カーボンブラックが分散された顔料分散液Ｂを得た。
【０２１３】
＜実施例１＞
以下の成分を混合し、十分攪拌して溶解後、ポアサイズ3.0μｍのミクロフィルター(富士フィルム製)にて加圧濾過し、本発明のインクを調製した。
上記の顔料分散液Ａ 45部
トリメチロールプロパン 6部
グリセリン 6部
ジエチレングリコール 6部
アセチレングリコールエチレンオキサイド付加物
(商品名:アセチレノールＥＨ) 0.2部
水酸化カリウム 0.06部
水 36.74部。
【０２１４】
＜実施例２＞
以下の成分を混合し、十分攪拌して溶解後、ポアサイズ3.0μｍのミクロフィルター(富士フィルム製)にて加圧濾過し、本発明のインクを調製した。
上記の顔料分散液Ａ 45部
安息香酸カリウム 1.7部
トリメチロールプロパン 6部
グリセリン 6部
ジエチレングリコール 6部
アセチレングリコールエチレンオキサイド付加物
(商品名:アセチレノールＥＨ) 0.2部
水 35.1部。
【０２１５】
＜参考例１＞
以下の成分を混合し、十分攪拌して溶解後、ポアサイズ3.0μｍのミクロフィルター(富士フィルム製)にて加圧濾過し、インクを調製した。
上記の顔料分散液Ｂ 45部
安息香酸カリウム 1.7部
トリメチロールプロパン 6部
グリセリン 6部
ジエチレングリコール 6部
アセチレングリコールエチレンオキサイド付加物
(商品名:アセチレノールＥＨ) 0.2部
水 35.1部。
【０２１６】
＜実施例３＞
以下の成分を混合し、十分攪拌して溶解後、ポアサイズ3.0μｍのミクロフィルター(富士フィルム製)にて加圧濾過し、本発明のインクを調製した。
上記の顔料分散液Ａ 45部
安息香酸アンモニウム 0.7部
安息香酸カリウム 0.9部
トリメチロールプロパン 6部
グリセリン 6部
ジエチレングリコール 6部
アセチレングリコールエチレンオキサイド付加物
(商品名:アセチレノールＥＨ) 0.2部
水 35.2部。
【０２１７】
＜実施例４＞
以下の成分を混合し、十分攪拌して溶解後、ポアサイズ3.0μｍのミクロフィルター(富士フィルム製)にて加圧濾過し、本発明のインクを調製した。
上記の顔料分散液Ａ 45部
安息香酸アンモニウム 1.5部
トリメチロールプロパン 6部
グリセリン 6部
ジエチレングリコール 6部
アセチレングリコールエチレンオキサイド付加物
(商品名:アセチレノールＥＨ) 0.2部
水酸化カリウム 0.06部
水 35.24部。
【０２１８】
＜比較例１＞
以下の成分を混合し、十分攪拌して溶解後、ポアサイズ3.0μｍのミクロフィルター(富士フィルム製)にて加圧濾過し、インクを調製した。
上記の顔料分散液Ａ 45部
トリメチロールプロパン 6部
グリセリン 6部
ジエチレングリコール 6部
アセチレングリコールエチレンオキサイド付加物
(商品名:アセチレノールＥＨ) 0.2部
アンモニア水(28％) 0.06部
水 36.74部。
【０２１９】
＜比較例２＞
以下の成分を混合し、十分攪拌して溶解後、ポアサイズ3.0μｍのミクロフィルター(富士フィルム製)にて加圧濾過し、インクを調製した。
上記の顔料分散液Ａ 45部
安息香酸リチウム 1.4部
トリメチロールプロパン 6部
グリセリン 6部
ジエチレングリコール 6部
アセチレングリコールエチレンオキサイド付加物
(商品名:アセチレノールＥＨ) 0.2部
水 35.4部。
【０２２０】
＜比較例３＞
以下の成分を混合し、十分攪拌して溶解後、ポアサイズ3.0μｍのミクロフィルター(富士フィルム製)にて加圧濾過し、インクを調製した。
上記の顔料分散液Ｂ 45部
安息香酸リチウム 1.4部
トリメチロールプロパン 6部
グリセリン 6部
ジエチレングリコール 6部
アセチレングリコールエチレンオキサイド付加物
(商品名:アセチレノールＥＨ) 0.2部
水 35.4部。
【０２２０】
＜比較例４＞
以下の成分を混合し、十分攪拌して溶解後、ポアサイズ3.0μｍのミクロフィルター(富士フィルム製)にて加圧濾過し、インクを調製した。
上記の顔料分散液Ａ 45部
安息香酸アンモニウム 1.5部
トリメチロールプロパン 6部
グリセリン 6部
ジエチレングリコール 6部
アセチレングリコールエチレンオキサイド付加物
(商品名:アセチレノールＥＨ) 0.2部
水 35.3部。
【０２２１】
このようにして得た実施例１〜４、参考例１及び比較例１〜４のブラックインクの主な特徴を下記表１にまとめて示した。
【０２２２】
【表１】

【０２２３】
上記の実施例１〜４、参考例１及び比較例１〜４のインクを用いて、記録信号に応じた熱エネルギーをインクに付与することによりインクを吐出させるオンデマンド型マルチ記録ヘッドを有するインクジェット記録装置ＢJＦ-850(キヤノン製)を何ら改造を施すことなく用いて下記評価を行なった。
【０２２４】
1)間欠吐出性
上記各インクと上記インクジェット記録装置を用い、Ａ４用紙（210ｍｍ×297ｍｍ、ＪIＳＰ0138-1961）１枚分の印字を行なった後２時間吐出を行なわず、その後再びＡ４用紙１枚分の印字を行なうサイクルを50回繰り返した。その時の印字の乱れ具合から上記各インクの間欠吐出性を評価した。
【０２２５】
2)固着性
上記各インクと上記インクジェット記録装置を用い、初期印字を行なった後72時間吐出を行なわず、その後再び印字を行なった。72時間吐出を行なわなかった後の印字が、初期印字の状態まで回復するのに要する記録装置の回復動作回数から上記各インクの固着性を評価した。
【０２２６】
上記の評価を行なった結果、実施例１のインクの間欠吐出性、固着性は共に比較例１のインクに比べて明らかに向上した。また実施例２のインクも比較例２のインクに比べて間欠吐出性、固着性が明らかに向上した。実施例３のインクについては、比較例３のインクに比べて間欠吐出性、固着性の向上が見られた。そして実施例３及び実施例４のインクは比較例４のインクに比べて間欠吐出性、固着性が明らかに向上した。
【０２２７】
【発明の効果】
インクジェット記録を行なう際にブラックインクによる印字において、印字物の印字濃度が高く、該インクが間欠吐出性および固着性に優れた水性顔料インクであり、更に該インクを用いたインクジェット記録方法及びインクジェット記録装置が提供された。
【図面の簡単な説明】
【図１】インクジェット記録装置のヘッドの一例を示す縦断面図である。
【図２】インクジェット記録装置のヘッドの一例を示す横断面図である。
【図３】図１に示したヘッドをマルチ化したヘッドの外観斜視図である。
【図４】インクジェット記録装置の一例を示す概略斜視図である。
【図５】インクカートリッジの一例を示す縦断面図である。
【図６】記録ユニットの一例を示す斜視図である。
【図７】インクジェット記録ヘッドの別の構成例を示す概略断面図である。
【図８】インクジェット記録ヘッドの製造方法の一例を工程順に配列した断面図である。
【図９】液体吐出ヘッドを搭載可能なインクジェットプリンタの一例の要部を示す概略斜視図である。
【図１０】液体吐出ヘッドを備えたインクジェットカートリッジの一例を示す概略斜視図である。
【図１１】液体吐出ヘッドの一例の要部を模式的に示す概略斜視図である。
【図１２】液体吐出ヘッドの一例の一部を抽出した概念図である。
【図１３】図12に示した吐出口の部分の拡大図である。
【図１４】図13に示した吐出口の部分のインク付着状態を示す模式図である。
【図１５】図12における主要部の模式図である。
【図１６】図15中のＸ−Ｙ斜視断面形状に対応し図17〜図23と共に液体吐出ヘッドの液体吐出動作を経時的に説明するための概略断面図である。
【図１７】図15中のＸ−Ｙ斜視断面形状に対応し図16及び図18〜図23と共に液体吐出ヘッドの液体吐出動作を経時的に説明するための概略断面図である。
【図１８】図15中のＸ−Ｙ斜視断面形状に対応し図16、図17及び図19〜図23と共に液体吐出ヘッドの液体吐出動作を経時的に説明するための概略断面図である。
【図１９】図15中のＸ−Ｙ斜視断面形状に対応し図16〜図18及び図20〜図23と共に液体吐出ヘッドの液体吐出動作を経時的に説明するための概略断面図である。
【図２０】図15中のＸ−Ｙ斜視断面形状に対応し図16〜図19及び図21〜図23と共に液体吐出ヘッドの液体吐出動作を経時的に説明するための概略断面図である。
【図２１】図15中のＸ−Ｙ斜視断面形状に対応し図16〜図20及び図22、図23と共に液体吐出ヘッドの液体吐出動作を経時的に説明するための概略断面図である。
【図２２】図15中のＸ−Ｙ斜視断面形状に対応し図16〜図21及び図23と共に液体吐出ヘッドの液体吐出動作を経時的に説明するための概略断面図である。
【図２３】図15中のＸ−Ｙ斜視断面形状に対応し図16〜図22と共に液体吐出ヘッドの液体吐出動作を経時的に説明するための概略断面図である。
【図２４】本発明の効果を発揮しやすい構成のヘッドを説明するための概略断面図の第一の例である。
【図２５】本発明の効果を発揮しやすい構成のヘッドを説明するための概略断面図の第二の例である。
【図２６】本発明の効果を発揮しやすい構成のヘッドを説明するための概略断面図の第三の例である。
【図２７】本発明の効果を発揮するメカニズムを説明するための概略模式図である。
【図２８】ナトリウムイオン等とカリウムイオンの水和性が異なる点を説明するための概念図である。
【図２９】本発明の液体吐出ヘッドを装着して適用することのできる液体吐出装置の一例であるインクジェット記録装置600の概略斜視図である。
【符号の説明】
１ 基板
２ インク吐出エネルギー発生素子
３ 開口部
４ 溶解可能な樹脂層
５ 被覆樹脂層
６ マスク
７ インク供給部材
８ インク吐出口
９ インク流路
13ヘッド
14インク溝
15発熱素子基板
16保護層
17-1、17-2電極
18発熱抵抗体層
19蓄熱層
20基板
21インク
22吐出オリフィス(微細孔)
23メニスカス
24インク小滴
25被記録材
26マルチノズル
27ガラス板
28発熱ヘッド
40インク袋
42栓
44インク吸収体
45インクカートリッジ
51給紙部
52紙送りローラー
53排紙ローラー
61ブレード
62キャップ
63インク吸収体
64吐出回復部
65記録ヘッド
66キャリッジ
67ガイド軸
68モーター
69ベルト
70記録ユニット
71ヘッド部
72大気連通口
80インク流路
81オリフィスプレート
82振動板
83圧電素子
84基板
85吐出口
251吐出エネルギー発生素子
252吐出口
253供給口
254基板
255吐出口プレート
261被覆樹脂層
262吐出エネルギー発生素子
263突起物
600インクジェット記録装置
601インクジェットヘッドカートリッジ
602駆動モータ
603、604駆動力伝達ギア
605リードスクリュ
606螺旋溝
607キャリッジ
607aレバー
608ガイド
609プラテンローラ
610紙押え板
611、612フォトカプラ
613支持部材
614キャップ部材
615インク吸引手段
616キャップ内開口部
617クリーニングブレード
618移動部材
619本体支持体
620(吸引開始)レバー
621カム
832:吐出口
832a:起部
832b:伏部
931:電気熱変換素子(ヒータ,インク吐出エネルギー発生素子)
933:インク供給口(開口部)
934:基板
935:オリフィスプレート(吐出口プレート)
935a:吐出口面
936:インク流路壁
936a :隔壁
940 :吐出口部
1337 :発泡室
1338 :液流路
1141 :溝
1141a:頂部
100 :インクジェット記録ヘッド
101 :気泡
102 :メニスカス
1001 :液体タンク
1006 :移動駆動部
1008 :ケーシング
1010 :記録部
1010a:キャリッジ部材
1012 :カートリッジ
1012Ｙ,Ｍ,Ｃ,Ｂ:インクジェットカートリッジ
1016 :ベルト
1018 :モータ
1020 :駆動部
1022a、1022b:ローラユニット
1024a、1024b:ローラユニット
1026 :回復ユニット
1026a、1026b:プーリ
1028 :用紙
1030 :搬送装置
2701 :カーボンブラック
2703 :水分子
2705 :カウンターイオン
2707 :カリウムイオン
2709 :ナトリウムイオン
Ｃ:濡れインク
Ｆ_M:メニスカス後退方向
Ｆ_C:メニスカス後退方向と反対方向
Ｇ:重心
I:インク
Ia:主液滴(液体,インク)
Ib,Ic:液体(インク)
Id:溝部に付着したインク(溝内のインク)
Ie:液流路内に残存しているインク
Ｌ:液室(インク供給口)から吐出口に向かう線
Ｎ₁:発泡室の幅寸法
Ｎ₂:発泡室の長さ寸法
Ｏ:吐出口の中心
Ｐ':被記録材
Ｐ:用紙の搬送方向
Ｒ:ベルトの回転方向
Ｓ:用紙の搬送方向と略直交する方向
Ｔ₁:吐出口伏部寸法
ｗ:隔壁の幅寸法[0001]
BACKGROUND OF THE INVENTION
  The present invention,The present invention relates to an inkjet ink, an inkjet recording method, an ink cartridge, an ink tank, a recording unit, an ink set, a fixing relaxation method, an image recording apparatus, a recording head, and an intermittent discharge improvement method.
[0002]
[Prior art]
Conventionally, inks for writing instruments (fountain pens, sign pens, water-based ballpoint pens, etc.) and ink-jet inks using carbon black, which has a high density of printed matter as a black colorant for printing inks and has excellent fastness, have various compositions. It has been reported. In particular, the composition of the carbon black itself so that it can record well on plain paper such as copy paper, report paper, notebooks, notepaper, bond paper and continuous slip paper that are commonly used in the office in recent years. Detailed research and development have been conducted on the physical properties, the composition of inks containing them, the physical properties, and the like.
[0003]
For example, JP-A-3-210373 discloses an aqueous inkjet ink containing acidic carbon black and an alkali-soluble polymer as a dispersant for carbon black. Japanese Patent Application Laid-Open No. 3-134073 discloses a storage stability and a discharge property in a bubble jet recording apparatus containing neutral or basic carbon black and a water-soluble resin as a dispersant thereof. Inkjet inks are described which are readily dispersible.
[0004]
Japanese Patent Application Laid-Open No. H8-3498 presents technical problems such as ink that contains carbon black together with a dispersing agent becomes unstable as an inkjet ink, and a sufficient print density cannot be obtained. As an ink that can be solved, an ink using self-dispersing carbon black that can be dispersed in a solvent without using a dispersant is disclosed. International Publication No. 96/18695 (Japanese Patent Publication No. 10-510862) and USP 5746818 (Japanese Patent Laid-Open No. 10-95941) also disclose an ink-jet ink containing self-dispersing carbon black, thereby improving the quality. It is described that a correct image can be obtained.
[0005]
Furthermore, the present inventors in European Patent Publication EP943666, when using the self-dispersing carbon black as an ink-jet ink, improve the image density dependency on paper type, reduce blurring at the boundary between black colors, etc. For the purpose, a technical means for adding a salt in addition to the self-dispersing carbon black has been disclosed.
[0006]
By the way, as an element which aims at the characteristic of the ink for inkjet, there are an intermittent ejection property of ink and an ink fixing property. Specifically, the intermittent ink discharge property refers to, for example, after discharging ink from a predetermined nozzle of an ink jet recording head, after the ink discharge from the nozzle is stopped for a certain long time (for example, about 12 hours), the ink discharge again. When ink is re-discharged from the nozzle, ink re-discharge is not stably performed and printing may be disturbed. In this manner, the operation of ejecting ink from a predetermined nozzle, and re-ejecting ink from the nozzle after the ejection from the nozzle is stopped for a predetermined time is called “intermittent ink ejection”. Instability is referred to as “intermittent ejection performance is poor”.
[0007]
Ink stickiness means that after ink ejection has been stopped for a long time (for example, several days or more), when ink is re-ejected from that nozzle again, ink that has increased in viscosity or solidified in the nozzle is eliminated. In order to obtain stable re-ejection, the recovery operation is necessary to obtain a stable re-ejection. What is required is called “poor adhesion”.
[0008]
In addition, for ink-jet inks, the characteristics required with the recent super-high image quality of ink-jet recorded images are becoming extremely sophisticated.
[0009]
[Problems to be solved by the invention]
However, for pigment inks containing the above-mentioned self-dispersing carbon black as a color material, particularly black pigment inks, a technology for providing high OD and sharp edges and achieving inkjet ejection characteristics such as intermittent ejection properties and fixing properties It cannot be said that sufficient knowledge has been accumulated, and there is a part that is not clear in the behavior as an ink for ink jet recording.
[0010]
For example, the ink containing self-dispersing carbon black and salt by the present inventors described above is the original purpose, which is to reduce the dependency of the image density on the paper type and to reduce the blur of the boundary area of the black color image. However, as a result of further studies aimed at establishing a better ink jet recording technology by the present inventors, there are significant fluctuations in the intermittent ejection property and fixing property of the ink depending on the structure of the recording head used. It was sometimes done.
[0011]
The structure of the recording head is expected to diversify with the development of a wide range of inkjet printer products in the future and the expansion of the application field of inkjet recording technology. Taking advantage of the excellent characteristics of ink containing self-dispersing carbon black At the same time, it has come to the recognition that the development of technology for inks that exhibit good and stable ink jet characteristics is necessary even with diversification of recording heads.
[0012]
Accordingly, an object of the present invention is to provide an ink that contains a pigment as a coloring material, in particular, self-dispersing carbon black, and has excellent ink jet recording characteristics.
[0013]
Another object of the present invention is to provide an image recording method capable of stably forming a high-quality inkjet recording image.
[0014]
Another object of the present invention is to provide an image recording apparatus capable of stably obtaining a high-quality printed matter, an ink cartridge used therein, and a recording unit.
[0015]
Another object of the present invention is to provide a method for alleviating the sticking property of an ink jet recording head.
[0016]
It is another object of the present invention to provide a recording head that is difficult to adhere.
[0017]
Another object of the present invention is to provide an ink-jet ink whose characteristics hardly change depending on the configuration of the recording head.
[0018]
Another object of the present invention is to provide an ink tank that can be suitably used for forming a high-quality image.
[0019]
Another object of the present invention is to provide a method for improving intermittent ejection in an ink jet recording method including a step of ejecting ink a plurality of times from the ink jet recording head at predetermined time intervals. It is an object of the present invention to provide a method for improving intermittent ejection properties when using a so-called side shooter type recording head that ejects liquid in a direction opposite to an element.
[0020]
[Means for Solving the Problems]
  Can achieve the above objectivesFor inkjetThe ink has at least one hydrophilic group on the surface of carbon black.OtherA coloring material containing at least a self-dispersing carbon black bonded through an atomic group, and an aqueous medium, and having a potassium ion of 0.6% or more by mass with respect to the carbon black, and the hydrophilic property The density of the group is 1.8μmol / m²It is the above.
[0021]
  In addition, a recording unit that can achieve the above-described object is a recording unit that includes an ink storage portion that stores ink and a recording head portion that discharges the ink as ink droplets. For example, at least one hydrophilic group on the surface of carbon blackOtherA coloring material containing at least a self-dispersing carbon black bonded through an atomic group, and an aqueous medium, and having a potassium ion of 0.6% or more by mass with respect to the carbon black, and the hydrophilic property The density of the group is 1.8μmol / m²That's itInk jet inkIt is characterized by that.
[0022]
  Further, an ink cartridge capable of achieving the above object is an ink cartridge having a tank housing portion for containing ink, wherein the ink is placed on at least one hydrophilic group, for example, on the surface of carbon black.OtherA coloring material containing at least a self-dispersing carbon black bonded through an atomic group, and an aqueous medium, and having a potassium ion of 0.6% or more by mass with respect to the carbon black, and the hydrophilic property The density of the group is 1.8μmol / m²That's itInk jet inkIt is characterized by that.
[0023]
  In addition, an image recording apparatus that can achieve the above object includes a recording unit having an ink storage section that stores ink and a recording head section that discharges the ink as ink droplets by the action of thermal energy. In the inkjet recording apparatus, at least one hydrophilic group is formed on the surface of, for example, carbon black.OtherA coloring material containing at least a self-dispersing carbon black bonded through an atomic group, and an aqueous medium, and having a potassium ion of 0.6% or more by mass with respect to the carbon black, and the hydrophilic property The density of the group is 1.8μmol / m²That's itInk jet inkIt is characterized by that.
[0024]
  An image recording method that can achieve the above-described object
  An image recording method including a step of applying energy to ink, causing the ink to be ejected from a recording head, and to adhere to a recording medium;
  Or, an image is recorded on a recording medium using an ink jet recording apparatus having a recording unit having an ink containing portion containing ink and a recording head portion for ejecting the ink as ink droplets by the action of thermal energy. Image recording method characterized by having a forming step
  The ink has, for example, at least one hydrophilic group on the surface of carbon black.OtherA coloring material containing at least a self-dispersing carbon black bonded through an atomic group, and an aqueous medium, and having a potassium ion of 0.6% or more by mass with respect to the carbon black, and the hydrophilic property The density of the group is 1.8μmol / m²That's itInk jet inkIt is characterized by that.
[0025]
  Further, the method of reducing the sticking of the recording head according to the present invention provides at least one hydrophilic group on the surface of, for example, carbon black when energy is applied to the ink and the ink is ejected from the recording head.OtherA coloring material containing at least a self-dispersing carbon black bonded through an atomic group, and an aqueous medium, and having a potassium ion of 0.6% or more by mass with respect to the carbon black, and the hydrophilic property The density of the group is 1.8μmol / m²The above ink-jet ink is used.
[0026]
  Further, the ink set that can achieve the above object is an ink containing at least one colorant selected from cyan, magenta, yellow, red, green, and blue, and a surface of, for example, carbon black And at least one hydrophilic groupOtherA coloring material containing at least a self-dispersing carbon black bonded through an atomic group, and an aqueous medium, and having a potassium ion of 0.6% or more by mass with respect to the carbon black, and the hydrophilic property The density of the group is 1.8μmol / m²That's itInk jet inkIt is characterized by that.
[0031]
  According to another embodiment of the present invention, there is provided an ink jet recording method comprising: a step of discharging ink using an ink jet recording head having an ink discharge port at a position facing an ink discharge pressure generating element. A method of alleviating sticking of a recording head, wherein the ink has at least one hydrophilic group on the surface of carbon black.OtherA coloring material containing at least a self-dispersing carbon black bonded through an atomic group, and an aqueous medium, and having a potassium ion of 0.6% or more by mass with respect to the carbon black, and the hydrophilic property The density of the group is 1.8μmol / m²The above ink-jet ink is used.
[0032]
  Further, another embodiment of the adhesion mitigating method according to the present invention is an ink jet recording method including a step of ejecting ink using an ink jet recording head having a portion where the flow path resistance of the liquid greatly changes in the ink flow path. A method of alleviating sticking of the recording head, wherein the ink has at least one hydrophilic group on the surface of carbon black.OtherA coloring material containing at least a self-dispersing carbon black bonded through an atomic group, and an aqueous medium, and having a potassium ion of 0.6% or more by mass with respect to the carbon black, and the hydrophilic property The density of the group is 1.8μmol / m²The above ink-jet ink is used.
[0033]
  Also, one embodiment of the method for improving intermittent discharge performance according to the present invention is an intermittent recording method in an ink jet recording method including a step of applying energy to the ink and repeating the step of discharging the ink from the recording head by the ink jet method at a predetermined time interval. A method for improving ejection properties, wherein the ink has at least one hydrophilic group on the surface of carbon black.OtherA coloring material containing at least a self-dispersing carbon black bonded through an atomic group, and an aqueous medium, and having a potassium ion of 0.6% or more by mass with respect to the carbon black, and the hydrophilic property The density of the group is 1.8μmol / m²The above ink-jet ink is used.
[0034]
  In another embodiment of the method for improving intermittent ejection performance according to the present invention, the step of ejecting ink a plurality of times at predetermined intervals using a recording head that ejects ink in a direction opposite to the ink ejection pressure generating element. A method for improving intermittent discharge in an ink jet recording method comprising:
At least one hydrophilic group on the surface of carbon blackOtherA coloring material containing at least a self-dispersing carbon black bonded through an atomic group, and an aqueous medium, and having a potassium ion of 0.6% or more by mass with respect to the carbon black, and the hydrophilic property The density of the group is 1.8μmol / m²The above ink-jet ink is used.
[0035]
  According to another embodiment of the method for improving intermittent discharge performance according to the present invention, ink is supplied at predetermined time intervals using a recording head having a portion in which the flow path resistance of the liquid greatly changes in the ink flow path. A method for improving intermittent discharge in an ink jet recording method including a step of discharging a plurality of times, wherein the ink has at least one hydrophilic group on the surface of carbon black.OtherA coloring material containing at least a self-dispersing carbon black bonded through an atomic group, and an aqueous medium, and having a potassium ion of 0.6% or more by mass with respect to the carbon black, and the hydrophilic property The density of the group is 1.8μmol / m²The above ink-jet ink is used.
[0036]
(Action)
As a result of conducting various experiments on the above problems, the present inventors have found that there is a correlation between the type of salt added to the ink and the structure of the recording head with respect to ink jet characteristics. For example, in the recording head shown in FIG. 24, 251 is an ejection energy generating element, 252 is an ejection port, 253 is a supply port, 254 is a substrate, and 255 is an ejection port plate.
[0037]
As is apparent from the figure, the ink is largely bent at the supply port and moves toward the ejection energy generating element. A value indicating the degree of ink bending at this time is an angle θ formed by the substrate of the supply port. When θ is 90 degrees or less, the ink is bent substantially 90 degrees or more. And in such a recording head, the case where the intermittent discharge property, the fixing property, etc. of ink differ greatly with the difference in the salt contained in ink was discovered.
[0038]
On the other hand, in a recording head having a structure in which there are few portions that disturb the flow of ink in the ink flow path, no remarkable difference was observed in the intermittent discharge property and the fixing property due to the difference in salt. Regardless of the structure of the recording head, all the salts that give excellent results are salts containing potassium, and the ink containing sodium salt or ammonium salt is potassium in terms of intermittent ejection and fixing properties in the recording head shown in FIG. It was inferior to the ink containing salt.
[0039]
The reason why the ink containing the potassium salt is excellent in intermittent discharge property and fixing property even in the recording head as shown in FIG. 24 is not clear. However, from the above knowledge, it was estimated that the salt in the ink had a great influence on the fluidity of the ink in the recording head.
[0040]
Specifically, the difference in intermittent discharge property and fixing property of the pigment ink is caused by the fact that the behavior of the cation ion added as a salt in the ink, particularly the behavior in the recording head, varies greatly depending on the recording head used. I guessed it. There are two possible causes for this, namely the behavior of the cation ion added as a salt and the behavior of the ink itself.
[0041]
First, the inventors' discussion on the behavior of ink using potassium salt as the salt will be described with reference to FIGS. FIG. 27 (1) is a schematic diagram showing the state of carbon black in an ink containing self-dispersing carbon black. In the drawing, 2701 represents self-dispersing carbon black, 2705 represents a counter ion of a hydrophilic group of carbon black, and 2703 represents a water molecule. The self-dispersing carbon black 2701 maintains a stable dispersed state by maintaining affinity with water molecules present in the surroundings.
[0042]
Here, FIG. 27 (2) shows the case where a potassium salt is added as a salt in the ink, and FIG. 27 (3) shows the case where a sodium salt is added. And potassium ions are negatively hydrating as shown in Fig. 28 (2), whereas sodium ions and lithium ions are positively hydrating ions as shown in Fig. 28 (1). It is.
[0043]
When sodium ions are present in the ink at a predetermined concentration, water molecules 2703 existing around the self-dispersing carbon black are localized on the sodium ion side as shown in FIG. 27 (3). Become. On the other hand, potassium ions are not significantly changed in the relationship between self-dispersing carbon black and water molecules even when compared with the case where potassium ions are not present.
[0044]
Of course, this state is a schematic depiction of the momentary state of each ink, and does not always indicate that it is in this state. I guess that. Therefore, the dispersion stability of carbon black in the ink containing sodium salt does not immediately decrease.
[0045]
However, as shown in FIG. 24, a recording head having a bent portion whose main flow direction of ink changes by 90 ° is considered to cause turbulence or disturbance in the flow state of the ink. May increase the apparent viscosity of the ink. And in such a recording head that causes disturbance in the flow state of ink, it is caused by the difference in the state of carbon black and water molecules as shown in FIGS. 27 (2) and (3) described later. It is believed that the difference in dispersion stability of self-dispersing carbon black has become apparent as a difference in intermittent ejection properties and sticking properties.
[0046]
And the present inventors came to make this invention based on such technical knowledge and consideration.
[0047]
In view of such a technical background, the present inventors have conducted detailed studies on the above-mentioned two points regarding pigments, in particular, inks using self-dispersing carbon black, and as a result of repeated detailed examinations such as the effects of single and composite effects. Even for carbon blacks with added salt for the purpose of reducing species dependence and reducing bleeding at the boundaries between black colors, for example, having a potassium ion of 0.6% or more by weight and having the hydrophilic groups Density is 1.8μmol / m²As described above, the ink has good intermittent ejection properties and fixing properties without depending greatly on the structure of the recording head to be used, and it is easier to use as an ink jet ink than before, and the image quality is also improved by the ink. The inventors have found that the present invention can be satisfied, and have made the present invention.
[0048]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in more detail with reference to preferred embodiments.
[0049]
One embodiment of the ink according to the present invention includes a colorant containing at least self-dispersing carbon black in which at least one hydrophilic group is bonded to the surface of carbon black directly or through another atomic group, and aqueous Including a medium, having a potassium ion of 0.6% or more by mass ratio with respect to carbon black, and the density of the hydrophilic group is 1.8 μmol / m 2²The ink is characterized by the above. Hereinafter, the constituent materials of the ink will be described.
[0050]
(Potassium ion)
The potassium ion concentration in the ink according to this aspect preferably has 0.6% or more of potassium ions by mass ratio with respect to carbon black. Further, when the mass ratio is less than 50% with respect to carbon black, the storage stability of the ink itself can be maintained at a very high level.
[0051]
In other words, when the potassium ion concentration is within this range, the ink can be formed as an ink for ink jet with a remarkable improvement in intermittent discharge property and fixing property. The improvement of the intermittent ejection property and the fixing property is that the pH value of the ink is adjusted to an appropriate range, and the potassium ion concentration in the ink is set to the above range rather than the effect of improving the dispersion stability of the self-dispersing carbon black. The present inventors consider that the effect of adjustment is greater.
[0052]
The above effect is achieved by the pH value of the ink when potassium hydroxide, potassium benzoate, or the like is added so that the potassium concentration in the ink falls within the above range, and the ink added with amines such as ammonia or triethanolamine. When adjusting the pH value equally and comparing the intermittent discharge properties and fixing properties of the respective inks, the ink with the potassium concentration adjusted to the above range has an intermittent discharge property and fixing property as compared with the ink having the same pH value. This is explained by the remarkable improvement. Even when compared with inks added with lithium and sodium belonging to the same alkali metals, there is an advantage in improving intermittent ejection properties and fixing properties of inks added with potassium.
[0053]
Of course, when the pH value is on the alkali side, the stability of the ink of the present invention is further improved. If this point is combined with the present invention, the effects of the present invention can be easily achieved. The preferred pH range of the ink used in the present invention is as follows. The anionic self-dispersing carbon black according to the present invention tends to lack dispersion stability in an acidic aqueous solution, and is preferably 7 or more and 10 or less in consideration of ink wettability with a recording head.
[0054]
Although the detailed reason why the ink of the present invention exhibits the above characteristics is unclear, self-dispersing carbon black is caused by the interaction of a predetermined amount of potassium ions in the ink and the hydrophilic group bonded to the surface of the carbon black. This is thought to be due to an improvement in the dispersion stability and redispersibility of the resin. That is, the idea of the present invention is fundamentally different from, for example, addition of potassium hydroxide or the like for solubilizing the dispersant, that is, addition for making the dispersion alkaline.
[0055]
Further, the ink used in the present invention has higher stability as a single ink on the alkali side than on the neutral region. However, the essence of the present invention is not to pursue only the stability of the ink alone, but rather to improve the stability in the vicinity of the ejection port. Also in this respect, the idea is fundamentally different from the addition of potassium hydroxide or the like for making the dispersion alkaline.
[0056]
Further, the mechanism that exerts the effect due to the presence of potassium ions will be described in detail below with reference to FIG. FIG. 27 is a schematic diagram for explaining the mechanism in which the presence of potassium ions brings about the effects of the present invention. In the figure, 2703 is a water molecule, 2709 is a sodium ion, 2707 is a potassium ion, 2701 is a self-dispersing carbon black, and 2705 is a counter ion of a hydrophilic group of the carbon black.
[0057]
As shown in FIG. 27 (1), the normal self-dispersing carbon black 2701 has a counter ion 2705, and a large number of water molecules 2703 exist around the hydrophilic group and the counter ion and are dispersed in a stable state. Next, it is presumed that the image in the case where a large amount of monovalent cation ions are present in the ink and cation ions are present in addition to the carbon counter is in the state shown in FIGS. 27 (2) and (3).
[0058]
That is, when a large amount of potassium ion 2707 is present as a cation ion other than the self-dispersing carbon black counter, there is not much difference from the state shown in FIG. 27 (1), and there is no deterioration in dispersion stability. On the other hand, when sodium ions exist as cations other than the counter around the self-dispersing carbon black, water molecules 2703 are located around the sodium ions 2709 rather than the self-dispersing carbon black 2701 as shown in FIG. It becomes easy to exist. As a result, it is assumed that the dispersion stability of the self-dispersing carbon black is deteriorated.
[0059]
At this time, it is considered that the difference shown in FIG. 27 hardly occurs depending on the type of counter ion, and the counter ion is not particularly limited to potassium ion, and may be sodium ion or the like. Naturally, the ions are moving in the ink, and the same ion does not always exist as a counter ion of carbon, and the ions in the ink are always exchanged, and the conceptual diagram shown in FIG. Is captured.
[0060]
However, when a large amount of potassium ions are present in the ink, the probability of being in the state of FIG. 27 (2) is high, and when a large amount of sodium ions is present, the probability of being in the state of FIG. 27 (3) is high. The difference between the two is considered to be due to the difference in hydration of ions. Compared to potassium ions, lithium ions, sodium ions, etc. are very hydrated.
[0061]
In view of this point, the present inventors consider that, as shown in FIG. 28, sodium ions and lithium ions exhibit a so-called positive hydration property, whereas potassium ions exhibit a negative hydration property. Yes. In other words, when sodium ions or lithium ions are present in the ink, water molecules that are inherently present around the self-dispersing carbon black and maintain the dispersion stability of the self-dispersing carbon black are the water molecules of these ions. This seems to be because it is separated from the surroundings of the self-dispersing carbon black due to the strength of the compatibility and exists around the cation ions.
[0062]
On the other hand, potassium ions have weaker hydration properties than self-dispersing carbon black, and we think that water molecules existing around self-dispersing carbon black rarely exist around them. Yes. FIG. 28 is a conceptual diagram for explaining the difference in hydration between sodium ions and potassium ions.
[0063]
Of course, it is ideal that all the self-dispersing carbon blacks in the ink are in the state as shown in FIG. 27 (2), but as a result of further earnest studies by the present inventors, the effects of the present invention are exhibited. Therefore, not all the self-dispersing carbon blacks are necessarily in the state as shown in FIG. 27 (2), and may be partially in the state as shown in FIG. 27 (3). That is, it has been found that the effects of the present invention can be exhibited even in a mixed system in the state as shown in FIGS. 27 (2) and 27 (3). That is, the present inventors have come to the conclusion that the effect of the present invention is exhibited if the mass ratio of potassium ions is 0.6% or more with respect to carbon black.
[0064]
As described above, the mechanism presumed by the present inventors has been described in detail. However, the technical idea of the present invention is that the monohydric cation ion present around the self-dispersing carbon black is weakly hydratable. It is important that it is weaker than the hydration property of self-dispersing carbon black. Accordingly, it is considered that any material having the same characteristics (non-affinity for water) as potassium ions other than potassium ions is within the scope of the technical idea of the present invention.
[0065]
In addition, the above phenomenon is more effective when a recording head having a part that disturbs the flow state of ink accompanying ink supply, for example, a recording head having a part in which the flow resistance greatly changes in the ink flow path is used. It will be remarkable. Although the details of the reason are not clear, the present inventors speculate as follows.
[0066]
The phenomenon described with reference to FIG. 27 is extremely difficult to occur in a sealed ink (in other words, a state in which no external factors other than time and gravity are applied). However, as described above, even with the same ink, the fixing property and the like vary greatly depending on the recording head used.
[0067]
In view of this point, the present inventors considered that something in the recording head caused a trigger to greatly deteriorate the dispersion stability of the ink, and as a result of intensive studies, it was not a constituent material in the recording head. It was clarified that it was due to the structure itself. In other words, the conclusion was reached that the flow resistance greatly changed in the ink flow path.
[0068]
(Self-dispersing carbon black)
Self-dispersing carbon black is carbon black in which at least one hydrophilic group is bonded to the surface of carbon black directly or through another atomic group. As a result of introducing this hydrophilic group onto the surface of carbon black, a dispersant for dispersing carbon black is not required as in conventional inks. As the self-dispersing carbon black, those having ionicity are preferable.
[0069]
Examples of the anionically charged carbon black include those in which a hydrophilic group as shown below is bonded to the surface of the carbon black.
-COOM, -SO_ThreeM, -PO_ThreeHM, -PO_ThreeM₂
In the above formula, M represents a hydrogen atom, an alkali metal, ammonium or organic ammonium, and among these, -COOM and -SO are particularly preferred._ThreeCarbon black in which M is bonded to the surface of carbon black and charged anionically has good dispersibility in the ink and can be used particularly preferably in this embodiment.
[0070]
By the way, among those represented as M in the hydrophilic group, specific examples of alkali metals include Li, Na, K, Rb and Cs, and specific examples of organic ammonium include, for example, methylammonium, dimethylammonium, Examples include trimethylammonium, ethylammonium, diethylammonium, triethylammonium, methanolammonium, dimethanolammonium, and trimethanolammonium.
[0071]
An ink containing self-dispersing carbon black in which M is ammonium or organic ammonium can further improve the water resistance of a recorded image, and can be suitably used in this respect. This is considered to be due to the fact that when the ink is applied onto the recording medium, ammonium is decomposed and ammonia is evaporated.
[0072]
The self-dispersing carbon black in which M is ammonium is, for example, a method in which self-dispersing carbon black in which M is an alkali metal is replaced with ammonium by using an ion exchange method or an acid is added to form H-type. Examples include a method of adding ammonium hydroxide to make M into ammonium.
[0073]
An example of a method for producing an anionically charged self-dispersing carbon black is a method in which carbon black is oxidized with sodium hypochlorite. By this method, a —COONa group is chemically bonded to the surface of carbon black. Can
it can.
[0074]
By the way, various hydrophilic groups as described above may be directly bonded to the surface of carbon black. Alternatively, other atomic groups may be interposed between the carbon black surface and the hydrophilic group, and the hydrophilic group may be indirectly bonded to the carbon black surface.
[0075]
Here, specific examples of the other atomic groups include, for example, a linear or branched alkylene group having 1 to 12 carbon atoms, a substituted or unsubstituted phenylene group, and a substituted or unsubstituted naphthylene group. Here, examples of the substituent of the phenylene group and the naphthylene group include linear or branched alkyl groups having 1 to 6 carbon atoms. Specific examples of combinations of other atomic groups and hydrophilic groups include, for example, -C₂H_Four-COOM, -Ph-SO_ThreeM, -Ph-COOM, etc. (where Ph represents a phenylene group, and M is defined as above).
[0076]
Furthermore, as a result of intensive studies by the present inventors, among the anionically charged self-dispersing carbon blacks as described above, the hydrophilic group density is 1.8 μmol / m 2.²It has been found that by using the above carbon black together with potassium, particularly excellent intermittent discharge properties and fixing properties are exhibited. This is because potassium ions are considered to improve the dispersion stability and redispersibility of the self-dispersing carbon black due to the interaction with the hydrophilic group. It is possible that this effect appears more sensitively.
[0077]
In the present invention, the self-dispersing carbon black contained in the ink is not limited to one type, and two or more types may be mixed and used to adjust the color tone. The addition amount of the self-dispersing carbon black in the pigment ink of the present invention is preferably 0.1% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass or less with respect to the total mass of the ink. Range. Further, the color tone of the ink may be adjusted using a dye in addition to the self-dispersing carbon black.
[0078]
(Hydrophilic group density)
As a method for measuring the hydrophilic group density of self-dispersing carbon black, for example, the carbon dispersion is purified, all the counter ions are sodium ions, this sodium ion is measured with a probe-type sodium electrode, and is contained in the entire dispersion. Obtain the amount of sodium ions to be obtained. There is a method of converting the sodium ion amount and the carbon black concentration in the dispersion into ppm per solid content. Conversion is performed on the assumption that hydrophilic groups such as carboxyl groups are present in the same number of moles as sodium ions as counter ions.
[0079]
Next, the recording head will be described. A head that exhibits the effects of the present invention more remarkably, that is, a recording head that is difficult to use when using the self-dispersing carbon black ink added with the salt disclosed by the present inventors. A recording head having a portion where the flow path resistance greatly changes in the ink flow path can be mentioned. As a specific example, for example, the following heads are listed as representative examples.
[0080]
1) The head chip has a portion where the flow path direction is bent substantially 90 degrees or more.
2) The head chip has a part whose surface energy is significantly different from the surrounding area.
3) The flow path width in the head chip has a part of 20μm or less.
The above portion is considered to further deteriorate the dispersibility of the ink whose dispersion has become partially unstable for some reason. Further details will be described below with reference to the drawings.
[0081]
First, the case of 1) will be described. 24 and 25 are schematic cross-sectional views of a head having a configuration in which the effects of the present invention are more remarkably exhibited. In the figure, 251 is an ejection energy generating element, 252 is an ejection port, 253 is a supply port, 254 is a substrate, and 255 is an ejection port plate.
[0082]
As is apparent from the figure, the ink is largely bent at the supply port and moves toward the ejection energy generating element. A value indicating the degree of ink bending at this time is an angle θ formed by the substrate of the supply port. When θ is 90 degrees or less, the ink is bent substantially 90 degrees or more.
[0083]
In this case, for example, it is considered that it becomes difficult to mix and uniform the inks by self-diffusion in the chip. In other words, since there is a portion where a certain stagnation-like portion is likely to be formed, the dispersion-stabilized ink is prevented from being stabilized by contact mixing with the ink whose dispersion is stable. Also, the ink flow state is disturbed or becomes a turbulent state, and the apparent viscosity of the ink rises. At this time, the influence of the self-dispersing carbon black that has become unstable as described above becomes obvious. Conceivable.
[0084]
Next, 2) will be described. FIG. 26 shows a schematic view of a head having a part where the surface energy is significantly different from the surroundings. In this schematic diagram, the part where the surface energy is significantly different from the surroundings is shown as a protrusion. In the figure, reference numeral 261 denotes a coating resin layer, 262 denotes a discharge energy generating element, and 263 denotes a protrusion. In this case, it is conceivable that the ink is trapped in the vicinity of the projection and difficult to move due to the difference in surface energy. Also, the ink flow state is disturbed or becomes a turbulent state, and the apparent viscosity of the ink rises. At this time, the influence of the self-dispersing carbon black that has become unstable as described above becomes obvious. Conceivable.
[0085]
Next, 3) will be described with reference to FIG. 26 as in 2). The portion indicated by A in the figure is narrower than the periphery in the ink flow path. Specifically, there is a portion of 20 μm or less. In such a head, as in the case of 1), the inks in the chip are difficult to mix and homogenize by self-diffusion. In other words, since there is a portion where a certain stagnation-like portion is likely to be formed, the dispersion-stabilized ink is prevented from being stabilized by contact mixing with the ink whose dispersion is stable. Also, the ink flow state is disturbed or becomes a turbulent state, and the apparent viscosity of the ink rises. At this time, the influence of the self-dispersing carbon black that has become unstable as described above becomes obvious. Conceivable.
[0086]
Of course, it goes without saying that the effects of the present invention become more remarkable when the above 1), 2) and 3) are combined. For example, the flow path width near the bent part is 20 μm or less. Furthermore, as an example in which the effect of the present invention is remarkably exhibited, an example in which the discharge amount per dot is 40 ng or less is used. This is because a recording head with a small ejection amount is likely to correspond to 3) in the example of the recording head having a portion where the flow path resistance changes greatly. Of course, the present invention is not limited to the above discharge amount.
[0087]
Next, a method for adjusting the potassium content in the ink will be described. Examples of the adjusting method include a method of adding in the form of a salt.
[0088]
Specifically, for example, potassium hydroxide, potassium benzoate, potassium phthalate, potassium acetate, potassium succinate, potassium citrate, potassium gluconate, potassium nitrate, potassium phosphate, potassium sulfate, potassium carbonate, potassium chloride, odor And potassium chloride. The potassium salts as described above can be used alone or as a mixture.
[0089]
Further, when potassium ions are added in the above-mentioned salt form, depending on the amount added, of course, some or all of the counter ions of the surface functional groups of the self-dispersing carbon black are replaced with potassium ions.
[0090]
(Monovalent cation ion)
The total amount of monovalent cation ions in the ink according to this embodiment is preferably in the range of 0.05 mol / L to 1 mol / L, particularly 0.1 mol / L to 0.5 mol / L, based on the total amount of the aqueous pigment ink. That is, when the total amount of monovalent cation ions is within this range, a high image density and a high quality image can be obtained, and there is no problem in ink characteristics such as storage stability.
[0091]
The reason why a high image density and a high-quality image as described above can be obtained is that the total amount of monovalent cation ions in the ink is included in the predetermined amount, so that the ink ejected from the nozzles adheres to the paper surface. This is probably because solid-liquid separation occurs promptly. For this phenomenon, the total amount of monovalent cation ions in the ink is important.
[0092]
In other words, if it is below a certain amount, specifically less than 0.05 mol / L, solid-liquid separation may not occur at the required rate. Conversely, if it exceeds 1 mol / L, the stability of the ink itself may be lost. It may not be preferable.
[0093]
As factors that cause this solid-liquid separation, capillarity, water evaporation, and the like can be considered, but the present inventors consider that the largest factor that causes solid-liquid separation of the ink of the present invention is water evaporation after ejection. . Of course, the capillary phenomenon on the paper after landing is one of the factors that cause solid-liquid separation, but the present inventors based on the following facts, the water evaporation after ejection causes maximum solid-liquid separation of the ink of the present invention. I think it is a factor.
[0094]
In the ink of the present invention, even on a clean glass surface, solid-liquid separation occurs faster than the ink in which the total amount of monovalent cation ions in the ink is not more than the predetermined amount. That is, the above fact clearly shows that the ink of the present invention undergoes solid-liquid separation even when capillary action does not occur. Therefore, the present inventors have come to consider that the greatest factor causing solid-liquid separation of the ink of the present invention is water evaporation after ejection.
[0095]
Here, the total amount of monovalent cation ions refers to the amount of all monovalent cation ions contained in the ink. That is, for example, a counter ion of a surface functional group of self-dispersing carbon black, a cation ion added as a pH adjusting agent, a cation ion added in the form of a salt, etc. are present as cation ions in the ink and are detected as cation ions. It means the amount of all cation ions that can be. Here, as a method for quantifying the cation ions in the ink, for example, combined use of an ion chromatograph and plasma emission spectroscopic analysis can be mentioned.
[0096]
Examples of monovalent cation ions include alkali metal ions, ammonium ions, and organic ammonium ions. More specifically, examples of alkali metal ions include lithium ions, sodium ions, potassium ions, and the like. Examples of organic ammonium ions include mono to tetramethyl ammonium ions, mono to tetraethyl ammonium ions, mono to tetramethanol ammonium ions, and the like.
[0097]
In order to adjust the total amount of cation ions in the ink, for example, a method of adding the cation as described above in the form of a salt can be mentioned. Examples of combinations of a cation ion and a counter anion when the cation ion is added in the form of a salt include the following:
One selected from ammonium ion, potassium ion, sodium ion, lithium ion, etc. as the cation ion, particularly ammonium ion,
One selected from halogen ions (chlorine ions, etc.), acetate ions, benzoate ions, etc. as anion ions.
[0098]
These salts give particularly excellent ink in terms of image density and image quality because of their excellent compatibility with self-dispersing carbon black.
[0099]
(Aqueous medium)
A preferable aqueous medium that can carry the above-described characteristics in the ink according to each of the above embodiments is water alone or a mixed solvent of water and a water-soluble organic solvent. As the water-soluble organic solvent, Those having the effect of preventing the ink from drying are particularly preferred, and it is desirable to use deionized water instead of general water containing various ions.
[0100]
(Water-soluble organic solvent)
Specific examples of the water-soluble organic solvent used in the present invention include carbon such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol. Alkyl alcohols of formulas 1 to 4; Amides such as dimethylformamide and dimethylacetamide; Ketones or ketoalcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Polyalkylene glycols such as polyethylene glycol and polypropylene glycol Class: ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, etc. Alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms; lower alkyl ether acetates such as polyethylene glycol monomethyl ether acetate; glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol Lower alkyl ethers of polyhydric alcohols such as monomethyl (or ethyl) ether; polyhydric alcohols such as trimethylolpropane and trimethylolethane; N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2- Examples include imidazolidinone and acetylene alcohol. The water-soluble organic solvents as described above can be used alone or as a mixture.
[0101]
The content of the water-soluble organic solvent as described above contained in the aqueous pigment ink of the present invention is not particularly limited, but is preferably in the range of 3% by mass to 50% by mass with respect to the total mass of the ink. The content of water contained in the ink is preferably in the range of 50% by mass to 95% by mass with respect to the total mass of the ink.
[0102]
Further, when it is necessary to adjust the surface tension of the ink, it is effective to appropriately add a predetermined amount of a surfactant such as acetylene alcohol represented by the following chemical formula, a permeable solvent, or the like.
[0103]
[Chemical 1]

[0104]
In addition to the above-mentioned components, the aqueous pigment ink of the present invention is added with a surfactant, an antifoaming agent, a preservative, an antifungal agent, etc., in order to obtain an ink having a desired physical property value as necessary. In addition, commercially available water-soluble dyes and the like can be added.
[0105]
As described above, the ink of the present invention is particularly effective when used in ink jet recording. As an ink jet recording method, there are a recording method in which mechanical energy is applied to ink to eject droplets, and a recording method in which thermal energy is applied to ink and ink droplets are ejected by ink firing. The ink of the present invention is particularly suitable.
[0106]
(Inkjet recording apparatus, inkjet recording method)
As an ink jet recording apparatus, first, a head configuration example which is a main part of an apparatus using thermal energy is shown in FIGS.
[0107]
FIG. 1 is a cross-sectional view of the head 13 along the ink flow path, and FIG. 2 is a cross-sectional view taken along line AB in FIG. The head 13 is obtained by bonding a glass, ceramic, silicon, or plastic plate having a flow path (nozzle) 14 through which ink passes and a heating element substrate 15. The heating element substrate 15 includes a protective layer 16 made of silicon oxide, silicon nitride, silicon carbide, etc., electrodes 17-1, 17-2 made of aluminum, gold, aluminum-copper alloy, etc., HfB₂Heating resistor layer 18 made of a high melting point material such as TaN, TaAl, etc., heat storage layer 19 made of thermally oxidized silicon, aluminum oxide, etc., and made of a material with good heat dissipation such as silicon, aluminum, aluminum nitride, etc. The substrate 20 is made up of.
[0108]
When pulsed electrical signals are applied to the electrodes 17-1 and 17-2 of the head, the region indicated by n of the heating element substrate 15 rapidly generates heat, and bubbles are formed in the ink 21 in contact with the surface. The generated meniscus 23 is projected by the generated pressure, and ink is ejected through the nozzle 14 of the head, becomes an ink droplet 24 from the ejection orifice 22, and flies toward the recording material 25.
[0109]
FIG. 3 shows an external view of a multi-head in which a large number of heads shown in FIG. 1 are arranged. This multi-head is made by adhering a glass plate 27 having multi-nozzles 26 and a heat-generating head 28 similar to that described in FIG.
[0110]
FIG. 4 shows an example of an ink jet recording apparatus incorporating this head. In FIG. 4, reference numeral 61 denotes a blade as a wiping member, one end of which is held and fixed by a blade holding member and forms a cantilever. The blade 61 is disposed at a position adjacent to the recording area by the recording head 65, and in this example, is held in a form protruding in the moving path of the recording head 65.
[0111]
62 is a cap on the surface of the projection port of the recording head 65, which is disposed at the home position adjacent to the blade 61, moves in a direction perpendicular to the moving direction of the recording head 65, abuts on the surface of the ink ejection port, and performs capping. The structure to perform is provided. Further, 63 is an ink absorber provided adjacent to the blade 61 and, like the blade 61, is held in a form protruding in the moving path of the recording head 65. The blade 61, the cap 62, and the ink absorber 63 constitute a discharge recovery unit 64, and the blade 61 and the ink absorber 63 remove moisture, dust, and the like from the discharge port surface.
[0112]
65 is a recording head that has discharge energy generating means and performs recording by discharging ink onto a recording material facing the discharge port surface on which the discharge port is disposed. 66 is a recording head mounted with the recording head 65. It is a carriage for moving. The carriage 66 is slidably engaged with the guide shaft 67, and a part of the carriage 66 is connected to a belt 69 (not shown) driven by a motor 68. As a result, the carriage 66 can move along the guide shaft 67, and the recording area by the recording head 65 and its adjacent area can be moved. 51 is a paper feeding unit for inserting a recording material, and 52 is a paper feed roller driven by a motor (not shown).
[0113]
With these configurations, a recording material is fed to a position opposite to the 65 discharge port surface of the recording head, and discharged to a paper discharge unit provided with a paper discharge roller 53 as recording progresses. In the above configuration, when the recording head 65 finishes recording and returns to the home position, the cap 62 of the ejection recovery unit 64 is retracted from the moving path of the recording head 65, but the blade 61 protrudes into the moving path. As a result, the ejection port of the recording head 65 is wiped.
[0114]
Note that when the cap 62 is in contact with the ejection surface of the recording head 65 to perform capping, the cap 62 moves so as to protrude into the moving path of the recording head. When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are in the same position as the above-described wiping position. As a result, the ejection port surface of the recording head 65 is wiped even during this movement.
[0115]
The above-mentioned movement of the recording head to the home position is not only at the end of recording or at the time of ejection recovery, but also to the home position adjacent to the recording area at a predetermined interval while the recording head moves the recording area for recording. Then, the wiping is performed with this movement.
[0116]
FIG. 5 is a diagram illustrating an example of an ink cartridge 45 that contains ink supplied to the recording head via an ink supply member, for example, a tube. Reference numeral 40 denotes an ink container, for example, an ink bag, in which supply ink is stored, and a rubber plug 42 is provided at the tip of the ink container. By inserting a needle (not shown) into the stopper 42, the ink in the ink bag 40 can be supplied to the head. 44 is an ink absorber for receiving waste ink. The ink container preferably has a liquid contact surface made of polyolefin, particularly polyethylene.
[0117]
The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separated as described above, but is preferably used in an apparatus in which they are integrated as shown in FIG. It is done. In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink storage portion that stores ink, for example, an ink absorber is stored, and the ink in the ink absorber from the head portion 71 having a plurality of orifices. The ink is ejected as ink droplets. For the present invention, it is preferable to use polyurethane as the material of the ink absorber.
[0118]
Alternatively, a structure may be used in which the ink container is an ink bag with a spring or the like inside without using an ink absorber. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the cartridge with the atmosphere. The recording unit 70 is used in place of the recording head 65 shown in FIG. 4 and is detachable from the carriage 66.
[0119]
Next, as a form of an ink jet recording apparatus using mechanical energy, a nozzle forming substrate having a plurality of nozzles, a pressure generating element made of a piezoelectric material and a conductive material disposed opposite to the nozzles, and the pressure generating element An on-demand ink jet recording head that includes ink that fills the periphery of the ink, displaces the pressure generating element by an applied voltage, and ejects small ink droplets from the nozzles. FIG. 7 shows a configuration example of a recording head which is a main part of the recording apparatus.
[0120]
The head includes an ink flow path 80 communicating with an ink chamber (not shown), an orifice plate 81 for ejecting ink droplets of a desired volume, a vibration plate 82 that directly applies pressure to ink, and the vibration plate 82 And a substrate 84 for indicating and fixing the orifice plate 81, the diaphragm and the like.
[0121]
In FIG. 7, the wall of the ink flow path 80 is formed of a photosensitive resin or the like, and the orifice plate 81 has a discharge port 85 formed by electroforming or punching a metal such as stainless steel or nickel. 82 is formed of a metal film such as stainless steel, nickel, or titanium and a highly elastic resin film, and the piezoelectric element 83 is formed of a dielectric material such as barium titanate or PZT.
[0122]
The recording head configured as described above applies a pulsed voltage to the piezoelectric element 83, generates a strain stress, deforms the diaphragm bonded to the piezoelectric element 83, and the ink in the ink flow path 80. Is pressed vertically to discharge ink droplets (not shown) from the discharge port 85 of the orifice plate to perform recording.
[0123]
Such a recording head is used by being incorporated in a recording apparatus similar to that shown in FIG. The detailed operation of the recording apparatus can be performed in the same manner as described above.
[0124]
FIG. 8A to FIG. 8F are cross-sectional views showing an example of a method for manufacturing a recording head that exhibits the effects of the present invention in order of steps. Of course, the present invention is not limited to a recording head manufactured based on this manufacturing method.
[0125]
First, a substrate 1 made of glass, ceramics, plastic, metal, or the like as shown in FIG. 8A is prepared.
[0126]
If such a substrate 1 functions as a part of a liquid flow path component and can function as a support for a material layer that forms an ink flow path and an ink discharge port described later, its shape, It can be used without any particular limitation on the material. A desired number of ink discharge energy generating elements 2 such as electrothermal conversion elements or piezoelectric elements are arranged on the substrate 1. Such ink ejection energy generating element 2 applies ejection energy for ejecting ink droplets to the ink liquid, and recording is performed.
[0127]
For example, when an electrothermal conversion element is used as the ink discharge energy generating element 2, the element heats a nearby recording liquid, thereby causing a change in state in the recording liquid and generating discharge energy. For example, when a piezoelectric element is used, ejection energy is generated by mechanical vibration of the element.
[0128]
These elements 2 are connected to control signal input electrodes (not shown) for operating these elements. In general, various functional layers such as a protective layer are provided for the purpose of improving the durability of these discharge energy generating elements. Of course, in the present invention, such a functional layer may be provided in one direction.
[0129]
In FIG. 8A, an example in which an opening 3 for supplying ink is provided in advance on the substrate 1 and ink is supplied from the back of the substrate 1 is illustrated. Any method can be used for forming the opening 3 as long as it is a means capable of forming a hole in the substrate 1. For example, it may be formed by mechanical means such as a drill, or light energy such as a laser may be used. Further, a resist pattern or the like may be formed on the substrate 1 and chemically etched.
[0130]
Of course, the opening 3 for supplying ink may not be formed in the substrate 1 but may be formed in a resin pattern and provided on the same surface as the ink discharge port 8 with respect to the substrate 1.
[0131]
Next, as shown in FIG. 8A, the ink flow path pattern 4 is formed on the substrate 1 with a soluble resin so as to cover the ink discharge energy generating element 2. The most common means is a means formed of a photosensitive material, but it can also be formed by means such as a screen printing method. In the case of using a photosensitive material, the ink flow path pattern can be dissolved, so that it is possible to use a positive resist or a solubility-changing negative resist.
[0132]
As a method for forming the resist layer, when using a substrate provided with an ink supply port on the substrate, the photosensitive material is dissolved in an appropriate solvent and applied onto a film such as PET (polyethylene terephthalate). It is preferable to form a dry film by drying and then laminating. As the above-mentioned dry film, vinyl ketone photodegradable polymer compounds such as polymethyl isopropyl ketone and polyvinyl ketone can be suitably used. This is because these compounds maintain the properties (film properties) as polymer compounds before light irradiation and can be easily laminated on the opening 3.
[0133]
Further, a filler that can be removed in a later step may be disposed in the opening 3 and a film may be formed by a normal spin coating method, roll coating method, or the like.
[0134]
On the dissolvable resin material layer 4 in which the ink flow path is patterned in this manner, as shown in FIG. 8B, a coating resin layer 5 is further formed by a normal spin coating method, roll coating method, or the like. Here, in the process of forming the covering resin layer 5, characteristics such as not allowing deformation of the dissolvable resin pattern are required. That is, when the coating resin layer 5 is dissolved in a solvent and formed on the resin pattern 4 that can be dissolved by spin coating, roll coating, or the like, it is necessary to select a solvent so as not to dissolve the soluble resin pattern 4. is there.
[0135]
Here, the coating resin layer 5 will be described. The coating resin layer 5 is preferably photosensitive because an ink discharge port described later can be easily and accurately formed by photolithography. Such a photosensitive coating resin layer 5 is required to have high mechanical strength as a structural material, adhesion to the substrate 1, ink resistance, and resolution for patterning a fine pattern of ink discharge ports at the same time. Is done. Here, it is found that the cationic polymerization cured product of an epoxy resin has excellent strength, adhesion, and ink property as a structural material, and has excellent patterning characteristics if the epoxy resin is solid at room temperature. It is.
[0136]
First, a cationic polymerization cured product of an epoxy resin has a high crosslink density (high Tg) as compared with a cured product of an ordinary acid anhydride or amine, and thus exhibits excellent characteristics as a structural material. Moreover, by using a solid epoxy resin at room temperature, diffusion of the polymerization initiating species generated from the cationic polymerization initiator by light irradiation into the epoxy resin can be suppressed, and excellent patterning accuracy and shape can be obtained.
[0137]
The step of forming the coating resin layer on the dissolvable resin layer is preferably formed by dissolving the solid coating resin in a solvent at room temperature and using a spin coating method.
[0138]
By using the spin coating method, which is a thin film coating technique, the coating resin layer 5 can be formed uniformly and accurately, and the distance (OH distance) between the ink ejection energy generating element 2 and the orifice, which has been difficult with the conventional method. ) Can be shortened, and small droplet discharge can be easily achieved.
[0139]
Further, when the above-described negative photosensitive material is used as the coating resin, reflection from the substrate surface and scum (development residue) usually occur. However, in the case of the present invention, since the ejection port pattern is formed on the ink flow path formed of a resin that can be dissolved, the influence of reflection from the substrate can be ignored, and the scum generated during development is the ink flow path described later. Since it is lifted off in the step of washing out the soluble resin that forms the resin, there is no adverse effect.
[0140]
The solid epoxy resin used in the present invention includes a reaction product of bisphenol A and epichlorohydrin having a molecular weight of about 900 or more, a reaction product of bromosphenol A and epichlorohydrin, phenol novolak or o-cresol novolak, Reaction product with epichlorohydrin, multi-sensitivity having an oxycyclohexane skeleton as described in JP-A-60-161973, JP-A-63-221121, JP-A-64-9216, JP-A-2-140219 An epoxy resin and the like can be mentioned, but of course the present invention is not limited to these compounds.
[0141]
Examples of the photocationic polymerization initiator for curing the epoxy resin include aromatic iodonium salts and aromatic sulfonium salts [see J. POLYMER SCI: Symposium No. 56, 383-395 (1976)] and Asahi Denka Kogyo Co., Ltd. SP-150, SP-170 etc. which are marketed more.
[0142]
Further, the above-mentioned photocationic polymerization initiator can promote cationic polymerization (increase the cross-linking density as compared with single photocationic polymerization) by heating with a reducing agent in combination. However, when a photocationic polymerization initiator and a reducing agent are used in combination, the reducing agent is selected so that it becomes a so-called redox type initiator system that does not react at room temperature but reacts at a certain temperature or higher (preferably 60 ° C or higher). There is a need.
[0143]
As such a reducing agent, copper triflate (copper trifluoromethanesulfonate (II)) is most suitable in consideration of the copper compound, in particular, reactivity and solubility in an epoxy resin. A reducing agent such as ascorbic acid is also useful. In addition, when a higher crosslink density (high Tg) is required, such as an increase in the number of nozzles (high-speed printability), use of non-neutral ink (improvement of water resistance of the colorant), the above-mentioned reducing agent is used as described later As described above, the crosslinking density can be increased by a post-process in which the coating resin layer is dipped and heated using the solution after the coating resin layer is developed.
[0144]
Furthermore, additives and the like can be appropriately added to the composition as necessary. For example, a flexibility imparting agent may be added for the purpose of lowering the elastic modulus of the epoxy resin, or a silane coupling agent may be added to obtain further adhesion to the substrate.
[0145]
Next, the photosensitive coating resin layer 5 made of the above compound is subjected to pattern exposure through a mask 6 as shown in FIG. The photosensitive coating resin layer 5 is a negative type, and a portion where an ink discharge port is formed is shielded with a mask. (Of course, the electrical connection is also shielded. Not shown).
[0146]
The pattern exposure can be appropriately selected from ultraviolet rays, deep-UV light, electron beams, X-rays and the like according to the photosensitive region of the photocationic polymerization initiator to be used.
[0147]
Here, all the steps so far can be aligned using conventional photolithography technology, and the accuracy can be significantly improved as compared with a method in which an orifice plate is separately prepared and bonded to a substrate. The photosensitive coating resin layer 5 that has been subjected to pattern exposure in this manner may be subjected to heat treatment in order to accelerate the reaction as necessary. Here, as mentioned above, the photosensitive coating resin layer is composed of a solid epoxy resin at room temperature, so diffusion of cationic polymerization initiating species generated by pattern exposure is restricted, and excellent patterning accuracy and shape are realized. it can.
[0148]
Next, the pattern-exposed photosensitive coating resin layer 5 is developed using an appropriate solvent to form ink ejection ports 8 as shown in FIG. 8 (d). Here, it is also possible to develop the dissolvable resin pattern 4 that forms the ink flow path simultaneously with the development of the unexposed photosensitive coating resin layer.
[0149]
However, in general, a plurality of heads of the same or different forms are arranged on the substrate 1 and used as an inkjet liquid discharge head through a cutting process. As shown, only the photosensitive coating resin layer 5 is selectively developed to leave the resin pattern 4 that forms the ink flow path 9 (the resin pattern 4 remains in the liquid chamber, so that dust generated during cutting does not enter. ) It is also possible to develop the resin pattern 4 after the cutting step (see FIG. 8E). At this time, scum (development residue) generated when developing the photosensitive coating resin layer 5 is eluted together with the soluble resin layer 4, so that no residue remains in the nozzle.
[0150]
When it is necessary to increase the crosslinking density as described above, the photosensitive coating resin layer 5 in which the ink flow path 9 and the ink discharge port 8 are formed is then immersed and heated in a solution containing a reducing agent. Is post-cured. Thereby, the crosslinking density of the photosensitive coating resin layer 5 further increases, and the adhesion to the substrate and the ink resistance are very good.
[0151]
Of course, the step of immersing and heating in the copper ion-containing solution can be carried out immediately after the photosensitive coating resin layer 5 is subjected to pattern exposure, development, and formation of the ink discharge port 8, and the resin that can be dissolved thereafter. The pattern 4 may be eluted. In the dipping and heating steps, heating may be performed while dipping, or heat treatment may be performed after dipping.
[0152]
As such a reducing agent, any substance having a reducing action is useful, but compounds containing copper ions such as copper triflate, copper acetate, copper benzoate are particularly effective. Among the above compounds, particularly copper triflate has a very high effect. In addition to the above, ascorbic acid is also useful.
[0153]
Electrical connection (not shown) for driving the ink supply member 7 and the ink discharge pressure generating element 2 is performed on the thus formed ink flow path and the substrate on which the ink discharge ports are formed. Thus, an ink jet liquid discharge head is formed (see FIG. 8F).
[0154]
In the present manufacturing example, the ink discharge port 8 is formed by photolithography. However, the present invention is not limited to this, and the ink discharge port 8 can be changed by dry etching using oxygen plasma or excimer laser by changing the mask. Can be formed. When the ink discharge port 8 is formed by excimer laser or dry etching, the substrate is protected by the resin pattern and is not damaged by the laser or plasma. Therefore, it is possible to provide a head with high accuracy and reliability. . Furthermore, when the ink discharge port 8 is formed by dry etching, excimer laser, or the like, the coating resin layer 5 may be a thermosetting material as well as a photosensitive material.
[0155]
Next, other specific examples of a recording apparatus and a recording head that can be suitably used in the present invention will be described. FIG. 9 is a schematic perspective view showing a main part of an example of a liquid discharge head as a liquid discharge head of a discharge method for communicating bubbles with the atmosphere during discharge according to the present invention, and an ink jet printer as a liquid discharge apparatus using this head. is there.
[0156]
In FIG. 9, the ink jet printer includes a transport device 1030 for intermittently transporting a sheet 1028 as a recording medium provided in the casing 1008 along the longitudinal direction in a direction indicated by an arrow P shown in FIG. The recording unit 1010 can be reciprocated substantially in a direction S substantially perpendicular to the conveyance direction P of the paper 1028, and a moving drive unit 1006 can be used as driving means for reciprocating the recording unit 1010.
[0157]
The movement drive unit 1006 is arranged substantially parallel to the belt 1016 wound around pulleys 1026a and 1026b arranged on the rotation shafts opposed to each other with a predetermined interval, and the roller units 1022a and 1022b, and the carriage member 1010a of the recording unit 1010. And a motor 1018 that drives a belt 1016 coupled to the forward and backward directions.
[0158]
When the motor 1018 is activated and the belt 1016 rotates in the direction of arrow R in FIG. 9, the carriage member 1010a of the recording unit 1010 is moved by a predetermined amount of movement in the direction of arrow S in FIG. When the motor 1018 is activated and the belt 1016 rotates in the direction opposite to the arrow R direction in FIG. 9, the carriage member 1010a of the recording unit 1010 has a predetermined direction in the direction opposite to the arrow S direction in FIG. It will be moved by the amount of movement. Further, a recovery unit 1026 for performing the recovery recovery process of the recording unit 1010 is opposed to the ink discharge port array of the recording unit 1010 at one end of the movement driving unit 1006 at a position that is the home position of the carriage member 1010a. Is provided.
[0159]
The recording unit 1010 is detachably attached to the carriage member 1010a for each color, for example, yellow, magenta, cyan, and black, for each of the ink jet cartridges (hereinafter sometimes simply referred to as cartridges) 1012Y, 1012M, 1012C, and 1012B. Provided.
[0160]
FIG. 10 shows an example of an ink jet cartridge that can be mounted on the above-described ink jet recording apparatus. The cartridge 1012 in this example is of a serial type, and the main part is composed of the ink jet recording head 100 and a liquid tank 1001 that stores a liquid such as ink.
[0161]
The ink jet recording head 100 is formed with a large number of ejection ports 832 for ejecting liquid, and liquid such as ink is supplied from a liquid tank 1001 through a liquid supply passage (not shown) to a common liquid chamber (see FIG. 11)). The cartridge 1012 integrally forms the ink jet recording head 100 and the liquid tank 1001 so that liquid can be replenished into the liquid tank 1001 as necessary. A structure in which the tanks 1001 are connected in a replaceable manner may be employed.
[0162]
A specific example of the above-described liquid discharge head that can be mounted on the ink jet printer having such a configuration will be described in more detail below.
[0163]
FIG. 11 is a schematic perspective view schematically showing the main part of the liquid discharge head showing the basic form of the present invention, and FIGS. 12 to 15 are front views showing the discharge port shape of the liquid discharge head shown in FIG. FIG. It should be noted that electrical wiring for driving the electrothermal transducer is omitted.
[0164]
In the liquid discharge head of this example, a substrate 934 made of glass, ceramics, plastic, metal, or the like as shown in FIG. 11 is used. The material of such a substrate is not the essence of the present invention, but functions as a part of the flow path component, and serves as a support for the material layer that forms the ink discharge energy generating element and the liquid flow path and discharge port described later. As long as it can function, it is not particularly limited. Therefore, in this example, a case where an Si substrate (wafer) is used will be described. In addition to the formation method using laser light, the discharge port can be formed by an exposure apparatus such as MPA (Mirror Projection Aligner) using, for example, an orifice plate (discharge port plate) 935 described later as a photosensitive resin.
[0165]
In FIG. 11, 934 is a substrate provided with an electrothermal conversion element (hereinafter sometimes referred to as a heater) 931 and an ink supply port 933 consisting of a long groove-like through-hole as a common liquid chamber portion. On both sides in the longitudinal direction, heaters 931 that are thermal energy generating means are arranged in a staggered manner with one row of heaters 931 arranged at intervals of 300 dpi, for example. On the substrate 934, an ink channel wall 936 for forming an ink channel is provided. The ink flow path wall 936 is further provided with a discharge port plate 935 having a discharge port 832.
[0166]
Here, in FIG. 11, the ink flow path wall 936 and the ejection port plate 935 are shown as separate members. However, the ink flow path wall 936 is formed on the substrate 934 by a technique such as spin coating. Thus, the ink flow path wall 936 and the discharge port plate 935 can be formed simultaneously as the same member. In this example, the discharge port surface (upper surface) 935a side is further subjected to water repellent treatment.
[0167]
In this example, a serial type head that performs recording while scanning in the direction of arrow S in FIG. 9 is used, for example, recording is performed at 1200 dpi. The drive frequency is 10 kHz, and one discharge port performs discharge at the shortest time interval of 100 μs.
[0168]
As an example of the actual dimensions of the head, for example, as shown in FIG. 12, the partition wall 936a that fluidly isolates adjacent nozzles has a width w = 14 μm. As shown in FIG. 15, the foaming chamber 1337 formed by the ink flow path wall 936 has N₁(Width dimension of foaming chamber) = 33μm, N₂(Length of foaming chamber) = 35 μm. The size of the heater 931 is 30 μm × 30 μm, the heater resistance value is 53Ω, and the drive voltage is 10.3V. Further, the ink flow path wall 936 and the partition wall 936a can be 12 μm in height and the discharge port plate thickness can be 11 μm.
[0169]
Of the cross section of the discharge port portion 940 provided on the discharge port plate including the discharge port 832, the shape of the cross section cut in the direction intersecting the ink discharge direction (thickness direction of the orifice plate 935) is approximately a star shape It is roughly constituted by six raised portions 832a having obtuse angles and six protuberances 832b alternately arranged between the raised portions 832a and having acute angles. That is, the bottom portion 832b as a region that is locally separated from the center O of the discharge port is the top portion, and the starting portion 832a as a region that is locally close to the center O of the discharge port adjacent to this region is the base portion. Six grooves are formed in the thickness direction (liquid discharge direction) of the orifice plate shown in FIG. 11 (see 1141a in FIG. 16 for the position of the groove).
[0170]
In this example, the discharge port portion 940 has a shape obtained by combining two equilateral triangles whose sides are cut in a direction crossing the thickness direction, for example, with a side of 27 μm and rotated by 60 degrees. T₁Is 8 μm. The angles of the raised parts 832a are all 120 degrees, and the angles of the prone parts 832b are all 60 degrees.
[0171]
Therefore, a polygon formed by connecting the center O of the discharge port and the center of the groove adjacent to each other (the center (center of gravity) of the figure formed by connecting the top of the groove and the two bases adjacent to the top). The center of gravity G of the two coincides with each other. The opening area of the discharge port 832 in this example is 400 μm²The opening area of the groove (the area of the figure formed by connecting the top of the groove and two bases adjacent to the top) is about 33 μm per piece.²It has become.
[0172]
FIG. 14 is a schematic diagram showing the ink adhering state of the discharge port portion shown in FIG. 13, and C represents the ink adhering portion.
[0173]
Next, a liquid discharge operation by the ink jet recording head having the above-described configuration will be described with reference to FIGS.
[0174]
16 to 23 are cross-sectional views for explaining the liquid discharge operation of the liquid discharge head shown in FIGS. 11 to 15, and are cross-sectional views taken along the line XX of the foaming chamber 1337 shown in FIG. In this cross section, the end of the discharge port portion 940 in the thickness direction of the orifice plate is a top portion 1141a of the groove 1141.
[0175]
FIG. 16 shows a state in which film-like bubbles are generated on the heater, FIG. 17 shows about 1 μs after FIG. 16, FIG. 18 shows about 2 μs after FIG. 16, FIG. 19 shows about 3 μs after FIG. 16 shows a state after about 4 μs, FIG. 21 shows a state after about 5 μs of FIG. 16, FIG. 22 shows a state after about 6 μs of FIG. 16, and FIG. 23 shows a state after about 7 μs of FIG. In the following description, “falling” or “falling” and “falling” do not mean dropping in the so-called gravitational direction, and the movement in the direction of the electrothermal transducer element is independent of the head mounting direction. Say.
[0176]
First, as shown in FIG. 16, when the bubble 101 is generated in the liquid flow path 1338 on the heater 931 due to the energization of the heater 931 based on the recording signal or the like, it is shown in FIGS. 17 and 18 for about 2 μs. As shown, it grows with rapid volume expansion. The height of the bubble 101 at the maximum volume exceeds the discharge port surface 935a. At this time, the pressure of the bubble is reduced from a fraction of the atmospheric pressure to a tenth of the atmospheric pressure.
[0177]
Next, at about 2 μs after the generation of the bubble 101, the bubble 101 changes from the maximum volume to the volume reduction as described above, and the formation of the meniscus 102 also starts almost simultaneously with this. This meniscus 102 also moves backward, that is, falls in the direction toward the heater 931 as shown in FIG.
[0178]
Here, in this example, since the plurality of grooves 1141 are dispersed in the discharge port portion, when the meniscus 102 is retracted, the meniscus retracting direction F in the groove 1141 portion._MDirection F opposite_CCapillary force acts on. As a result, even if some variation is recognized in the state of the bubble 101 for some reason, the shape of the meniscus and the main droplet (hereinafter sometimes referred to as liquid or ink) Ia when the meniscus is retracted, Correction is made so as to have a substantially symmetrical shape with respect to the center of the discharge port.
[0179]
In this example, since the falling speed of the meniscus 102 is faster than the contraction speed of the bubble 101, the bubble 101 is near the lower surface of the discharge port 832 at a time point about 4 μs after the generation of the bubble as shown in FIG. Communicate with the atmosphere. At this time, the liquid (ink) near the central axis of the ejection port 832 falls toward the heater 931. This is because the liquid (ink) Ia drawn back to the heater 931 side by the negative pressure of the bubble 101 before communicating with the atmosphere maintains the velocity in the heater 931 surface direction by inertia even after the bubbles 101 communicate with the atmosphere. It is.
[0180]
The liquid (ink) that has fallen toward the heater 931 reaches the surface of the heater 931 at about 5 μs after the generation of the bubble 101 as shown in FIG. 21, and as shown in FIG. It spreads to cover the surface. Thus, the liquid spread so as to cover the surface of the heater 931 has a horizontal vector along the surface of the heater 931, but intersects the surface of the heater 931, for example, the vertical vector disappears, and the heater 931 It tries to stay on the surface and pulls the liquid above it, that is, the liquid that maintains the velocity vector in the discharge direction, downward.
[0181]
Thereafter, the liquid portion Ib between the liquid spread on the surface of the heater 931 and the upper liquid (main droplet) becomes thinner, and at about 7 μs after the generation of the bubble 101, as shown in FIG. The liquid portion Ib is cut at the center of the surface of 1 to be separated into a main droplet Ia that maintains a velocity vector in the discharge direction and a liquid Ic that spreads on the surface of the heater 931. As described above, the separation position is preferably inside the liquid flow path 1338, more preferably on the electrothermal conversion element 931 side than the discharge port 832.
[0182]
The main liquid droplet Ia is discharged from the central portion of the discharge port 832 without being biased in the discharge direction, and is discharged at a predetermined position on the recording surface of the recording medium. In addition, the liquid Ic that has spread on the surface of the heater 931 conventionally fly as satellite droplets following the main droplet, but stays on the surface of the heater 931 and is not discharged.
[0183]
As described above, since the discharge of the satellite droplets can be suppressed, it is possible to prevent the splash that is likely to occur due to the discharge of the satellite droplets, and it is ensured that the recording surface of the recording medium is soiled by the mist floating in the form of mist. Can be prevented. 20 to 23, Id represents ink attached to the groove (ink in the groove), and Ie represents ink remaining in the liquid flow path.
[0184]
As described above, in the liquid discharge head of the present example, when discharging liquid at the volume reduction stage after the bubbles grow to the maximum volume, the plurality of grooves dispersed with respect to the center of the discharge port causes the main at the time of discharge. The direction of the droplet can be stabilized. As a result, it is possible to provide a liquid ejection head that has no deviation in the ejection direction and has high landing accuracy. In addition, high-speed and high-definition printing can be realized due to stable ejection even with respect to foaming variation at a high driving frequency.
[0185]
In particular, by discharging the liquid by first communicating with the atmosphere at the bubble volume reduction stage, it is possible to prevent mist that is generated when the bubbles are communicated with the atmosphere and the liquid droplets are ejected. It is also possible to suppress a state in which droplets adhere to the discharge port surface, which causes undischarge.
[0186]
In addition, as another embodiment of the recording head of the ejection method that can be suitably used in the present invention and communicates bubbles with the atmosphere during ejection, for example, as described in Japanese Patent Registration No. 2783647, a so-called edge shooter type can be mentioned. .
[0187]
The present invention provides an excellent effect particularly in an ink jet recording head and a recording apparatus that perform recording by forming flying droplets using thermal energy among ink jet recording methods.
[0188]
As its typical configuration and principle, for example, those performed using the basic principle disclosed in US Pat. Nos. 4,723,129 and 4740796 are preferable. This method can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding the nucleate boiling to the electrothermal transducer, the thermal energy is generated in the electrothermal transducer, and the recording head This is effective because film boiling occurs on the heat acting surface, and as a result, bubbles in the liquid (ink) corresponding to the drive signal on a one-to-one basis can be formed. By the growth and contraction of the bubbles, liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable that the drive signal has a pulse shape, because the bubble growth and contraction is performed immediately and appropriately, and thus it is possible to achieve discharge of a liquid (ink) having particularly excellent responsiveness.
[0189]
As this pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,434,262 are suitable. Further excellent recording can be performed by employing the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface.
[0190]
As the configuration of the recording head, in addition to the combination configuration (straight liquid flow path or right-angle liquid flow path) of the discharge port, the liquid path, and the electrothermal transducer as disclosed in each of the above specifications, the thermal action A configuration using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose a configuration in which the portion is arranged in a bent region, is also included in the present invention.
[0191]
In addition, for a plurality of electrothermal transducers, Japanese Patent Application Laid-Open No. 59-123670 which discloses a configuration in which a common slit is used as a discharge portion of an electrothermal transducer or an opening for absorbing a pressure wave of thermal energy. The present invention is also effective as a configuration based on Japanese Patent Application Laid-Open No. 59-138461 which discloses a configuration corresponding to the discharge unit.
[0192]
Furthermore, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is satisfied by a combination of a plurality of recording heads as disclosed in the above specification. Either the configuration or the configuration as a single recording head formed integrally may be used, but the present invention can exhibit the above-described effects more effectively.
[0193]
In addition, the ink is integrated into the replaceable chip type recording head or the recording head itself, which can be electrically connected to the apparatus main body and supplied with ink from the apparatus main body by being attached to the apparatus main body. The present invention is also effective when a cartridge type recording head provided with a tank is used.
[0194]
In addition, it is preferable to add recovery means for the recording head, preliminary auxiliary means, and the like provided as the configuration of the recording apparatus of the present invention, since the effects of the present invention can be further stabilized. Specifically, capping means, cleaning means, pressurizing or suction means for the recording head, preheating means using a heating element different from this, or a combination thereof, or recording is used. It is also effective to perform a preliminary discharge mode for performing another discharge in order to perform stable recording.
[0195]
Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but the recording head may be integrally formed or may be a combination of a plurality of colors. The present invention is extremely effective for an apparatus having at least one of full colors.
[0196]
In the embodiments of the present invention described above, the ink is described as a liquid. However, the ink is solidified at room temperature or lower and softens at room temperature, or is a liquid, or the above-described ink jet system. In general, the temperature of the ink itself is adjusted within a range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is within the stable ejection range. Anything you want.
[0197]
In addition, it is possible to prevent the temperature rise by heat energy from being used as the energy for changing the state of the ink from the solid state to the liquid state, or to use ink that solidifies in the standing state for the purpose of preventing ink evaporation. In any case, thermal energy such as ink that liquefies by application according to a recording signal of thermal energy and ejects as liquid ink, or that starts to solidify when it reaches the recording medium, etc. The use of ink having the property of being liquefied for the first time is also applicable to the present invention. In such a case, the ink is in a state of being held as a liquid or solid in a porous sheet recess or through-hole as described in JP-A-54-56847 or JP-A-60-71260, It is good also as a form which opposes with respect to an electrothermal converter. In the present invention, the most effective one for each of the above-described inks is to execute the above-described film boiling method.
[0198]
In addition, as a form of the recording apparatus according to the present invention, in addition to an image output terminal of an information processing device such as a word processor or a computer, a copying apparatus combined with a reader and a transmission / reception function are provided. It may be in the form of a facsimile machine having the same.
[0199]
Next, an outline of a liquid discharge apparatus equipped with the above-described liquid discharge head will be described.
[0200]
FIG. 29 is a schematic perspective view of an ink jet recording apparatus 600 which is an example of a liquid ejecting apparatus that can be applied with the liquid ejecting head of the present invention.
[0201]
In FIG. 29, an ink jet head cartridge 601 is formed by integrating the above-described liquid discharge head and an ink tank that holds ink supplied to the liquid discharge head. The ink jet head cartridge 601 is mounted on a carriage 607 that engages with a spiral groove 606 of a lead screw 605 that rotates via driving force transmission gears 603 and 604 in conjunction with forward and reverse rotation of a driving motor 602. The drive motor 602 reciprocates in the directions of arrows a and b along the guide 608 together with the carriage 607. The recording material P ′ is conveyed on the platen roller 609 by a recording material conveying means (not shown), and is pressed against the platen roller 609 by the paper pressing plate 610 over the moving direction of the carriage 607.
[0202]
Photocouplers 611 and 612 are disposed near one end of the lead screw 605. These are home position detecting means for confirming the presence of the lever 607a of the carriage 607 in this region and switching the rotation direction of the drive motor 602.
[0203]
The support member 613 supports a cap member 614 that covers the front surface (discharge port surface) where the above-described inkjet head cartridge 601 has a discharge port. Further, the ink suction means 615 sucks ink that has been discharged from the inkjet head cartridge 601 and accumulated in the cap member 614. By the ink suction means 615, suction recovery of the ink jet head cartridge 601 is performed through an opening in the cap (not shown). A cleaning blade 617 for wiping the discharge port surface of the inkjet head cartridge 601 is provided so as to be movable in the front-rear direction (a direction orthogonal to the moving direction of the carriage 607) by a moving member 618. The cleaning blade 617 and the moving member 618 are supported by the main body support 619. The cleaning blade 617 is not limited to this form, and may be another known cleaning blade.
[0204]
In the suction recovery operation of the liquid ejection head, the lever 620 for starting suction moves with the movement of the cam 621 engaged with the carriage 607, and the driving force from the driving motor 602 is a known transmission such as clutch switching. The movement is controlled by means. An ink jet recording control unit that gives a signal to a heating element provided in the liquid discharge head of the ink jet head cartridge 601 and controls driving of each mechanism described above is provided on the apparatus main body side. Not shown.
[0205]
In the inkjet recording apparatus 600 having the above-described configuration, the inkjet head cartridge 601 reciprocates over the entire width of the recording material P ′ with respect to the recording material P ′ conveyed on the platen roller 609 by a recording material conveyance means (not shown). While recording.
[0206]
【Example】
Hereinafter, although it demonstrates more concretely using an Example and a comparative example, this invention is not limited by the following Example, unless the summary is exceeded. In the following description, “parts” and “%” are based on mass unless otherwise specified.
[0207]
(Preparation of pigment dispersion)
[Pigment dispersion A]
1.58 g of anthranilic acid was added to a solution of 5 g of concentrated hydrochloric acid in 5.3 g of water at 5 ° C. To this, a solution obtained by adding 1.78 g of sodium nitrite to 8.7 g of water at 5 ° C. was added in a state where the temperature was constantly kept at 10 ° C. or less by stirring with an ice bath.
[0208]
Furthermore, after stirring for 15 minutes, the surface area is 220m.²7 g of carbon black having a DBP oil absorption of 105 mL / 100 g was added in a mixed state. Thereafter, the mixture was further stirred for 15 minutes. The obtained slurry was filtered with Toyo filter paper No. 2 (manufactured by Advantis), the pigment particles were washed thoroughly with water and dried in an oven at 110 ° C., and water was added to the pigment to add a pigment concentration of 10% by mass. An aqueous pigment solution was prepared.
[0209]
When the hydrophilic group density of the self-dispersing carbon black produced above was measured as follows, it was 2.6 μmol / m.²Met. As a measuring method, an ion meter (manufactured by DKK) was used to measure the sodium ion concentration, and the hydrophilic group density was converted from the value. Then, by replacing sodium ions with ammonium ions using an ion exchange method, the surface of carbon black is changed to -Ph-COONH._FourA pigment dispersion A in which a self-dispersing carbon black having a group introduced therein was dispersed was obtained.
[0210]
[Pigment dispersion B]
1.58 g of anthranilic acid was added to a solution of 5 g of concentrated hydrochloric acid in 5.3 g of water at 5 ° C. To this, a solution obtained by adding 1.78 g of sodium nitrite to 8.7 g of water at 5 ° C. was added in a state where the temperature was constantly kept at 10 ° C. or less by stirring with an ice bath.
[0211]
Furthermore, after stirring for 15 minutes, the surface area is 220m.²8 g of carbon black having a DBP oil absorption of 105 mL / 100 g was added in a mixed state. Thereafter, the mixture was further stirred for 15 minutes. The obtained slurry was filtered with Toyo filter paper No. 2 (manufactured by Advantis), the pigment particles were washed thoroughly with water and dried in an oven at 110 ° C., and water was added to the pigment to add a pigment concentration of 10% by mass. An aqueous pigment solution was prepared.
[0212]
When the hydrophilic group density of the self-dispersing carbon black prepared above was measured in the same manner as described above, it was 1.6 μmol / m.²Met. Then, by replacing sodium ions with ammonium ions using an ion exchange method, the surface of carbon black is changed to -Ph-COONH._FourA pigment dispersion B in which the self-dispersing carbon black introduced with a group was dispersed was obtained.
[0213]
<Example 1>
The following components were mixed, sufficiently stirred and dissolved, and then pressure filtered through a microfilter (manufactured by Fuji Film) having a pore size of 3.0 μm to prepare the ink of the present invention.
45 parts of the above pigment dispersion A
6 parts trimethylolpropane
Glycerin 6 parts
Diethylene glycol 6 parts
Acetylene glycol ethylene oxide adduct
(Product name: Acetylenol EH) 0.2 parts
Potassium hydroxide 0.06 parts
36.74 parts of water.
[0214]
<Example 2>
The following components were mixed, sufficiently stirred and dissolved, and then pressure filtered through a microfilter (manufactured by Fuji Film) having a pore size of 3.0 μm to prepare the ink of the present invention.
45 parts of the above pigment dispersion A
Potassium benzoate 1.7 parts
6 parts trimethylolpropane
Glycerin 6 parts
Diethylene glycol 6 parts
Acetylene glycol ethylene oxide adduct
(Product name: Acetylenol EH) 0.2 parts
35.1 parts of water.
[0215]
<Reference Example 1>
The following components were mixed, sufficiently stirred and dissolved, and then pressure filtered through a microfilter (manufactured by Fuji Film) having a pore size of 3.0 μm to prepare an ink.
45 parts of the above pigment dispersion B
Potassium benzoate 1.7 parts
6 parts trimethylolpropane
Glycerin 6 parts
Diethylene glycol 6 parts
Acetylene glycol ethylene oxide adduct
(Product name: Acetylenol EH) 0.2 parts
35.1 parts of water.
[0216]
<Example 3>
The following components were mixed, sufficiently stirred and dissolved, and then pressure filtered through a microfilter (manufactured by Fuji Film) having a pore size of 3.0 μm to prepare the ink of the present invention.
45 parts of the above pigment dispersion A
0.7 parts of ammonium benzoate
Potassium benzoate 0.9 parts
6 parts trimethylolpropane
Glycerin 6 parts
Diethylene glycol 6 parts
Acetylene glycol ethylene oxide adduct
(Product name: Acetylenol EH) 0.2 parts
35.2 parts of water.
[0217]
<Example 4>
The following components were mixed, sufficiently stirred and dissolved, and then pressure filtered through a microfilter (manufactured by Fuji Film) having a pore size of 3.0 μm to prepare the ink of the present invention.
45 parts of the above pigment dispersion A
Ammonium benzoate 1.5 parts
6 parts trimethylolpropane
Glycerin 6 parts
Diethylene glycol 6 parts
Acetylene glycol ethylene oxide adduct
(Product name: Acetylenol EH) 0.2 parts
Potassium hydroxide 0.06 parts
35.24 parts of water.
[0218]
<Comparative Example 1>
The following components were mixed, sufficiently stirred and dissolved, and then pressure filtered through a microfilter (manufactured by Fuji Film) having a pore size of 3.0 μm to prepare an ink.
45 parts of the above pigment dispersion A
6 parts trimethylolpropane
Glycerin 6 parts
Diethylene glycol 6 parts
Acetylene glycol ethylene oxide adduct
(Product name: Acetylenol EH) 0.2 parts
Ammonia water (28%) 0.06 parts
36.74 parts of water.
[0219]
<Comparative example 2>
The following components were mixed, sufficiently stirred and dissolved, and then pressure filtered through a microfilter (manufactured by Fuji Film) having a pore size of 3.0 μm to prepare an ink.
45 parts of the above pigment dispersion A
Lithium benzoate 1.4 parts
6 parts trimethylolpropane
Glycerin 6 parts
Diethylene glycol 6 parts
Acetylene glycol ethylene oxide adduct
(Product name: Acetylenol EH) 0.2 parts
35.4 parts of water.
[0220]
<Comparative Example 3>
The following components were mixed, sufficiently stirred and dissolved, and then pressure filtered through a microfilter (manufactured by Fuji Film) having a pore size of 3.0 μm to prepare an ink.
45 parts of the above pigment dispersion B
Lithium benzoate 1.4 parts
6 parts trimethylolpropane
Glycerin 6 parts
Diethylene glycol 6 parts
Acetylene glycol ethylene oxide adduct
(Product name: Acetylenol EH) 0.2 parts
35.4 parts of water.
[0220]
<Comparative example 4>
The following components were mixed, sufficiently stirred and dissolved, and then pressure filtered through a microfilter (manufactured by Fuji Film) having a pore size of 3.0 μm to prepare an ink.
45 parts of the above pigment dispersion A
Ammonium benzoate 1.5 parts
6 parts trimethylolpropane
Glycerin 6 parts
Diethylene glycol 6 parts
Acetylene glycol ethylene oxide adduct
(Product name: Acetylenol EH) 0.2 parts
35.3 parts of water.
[0221]
The main characteristics of the black inks of Examples 1 to 4, Reference Example 1 and Comparative Examples 1 to 4 thus obtained are summarized in Table 1 below.
[0222]
[Table 1]

[0223]
Inkjet having an on-demand type multi-recording head that ejects ink by applying thermal energy corresponding to a recording signal to the ink using the inks of Examples 1 to 4, Reference Example 1 and Comparative Examples 1 to 4 The following evaluation was performed using a recording device BJF-850 (manufactured by Canon Inc.) without any modification.
[0224]
1) Intermittent discharge
A cycle in which printing is performed for one sheet of A4 paper (210 mm × 297 mm, JISP0138-1961) using each of the inks and the ink jet recording apparatus, and then printing is performed again for one sheet of A4 paper without discharging for 2 hours. Was repeated 50 times. The intermittent ejection property of each ink was evaluated from the printing disorder at that time.
[0225]
2) Adhesiveness
Using each of the inks and the ink jet recording apparatus, after the initial printing, the ink was not discharged for 72 hours, and then the printing was performed again. The sticking property of each ink was evaluated from the number of recovery operations of the recording apparatus required to recover the printing after 72 hours of no ejection.
[0226]
  As a result of the above evaluation, both the intermittent discharge property and the fixing property of the ink of Example 1 were clearly improved as compared with the ink of Comparative Example 1. Further, the ink of Example 2 also clearly improved the intermittent discharge property and the sticking property as compared with the ink of Comparative Example 2. As for the ink of Example 3, the intermittent ejection property and the fixing property were improved as compared with the ink of Comparative Example 3. And examples3And examples4In comparison with the ink of Comparative Example 4, the ink of No. 5 was clearly improved in intermittent ejection property and fixing property.
[0227]
【The invention's effect】
When printing with black ink during ink jet recording, the print density of the printed matter is high, and the ink is an aqueous pigment ink excellent in intermittent ejection and fixing properties. Further, an ink jet recording method and ink jet recording using the ink A device was provided.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an example of a head of an ink jet recording apparatus.
FIG. 2 is a cross-sectional view illustrating an example of a head of an ink jet recording apparatus.
FIG. 3 is an external perspective view of a head in which the head shown in FIG.
FIG. 4 is a schematic perspective view illustrating an example of an ink jet recording apparatus.
FIG. 5 is a longitudinal sectional view showing an example of an ink cartridge.
FIG. 6 is a perspective view illustrating an example of a recording unit.
FIG. 7 is a schematic cross-sectional view showing another configuration example of the ink jet recording head.
FIG. 8 is a cross-sectional view in which an example of a method for manufacturing an ink jet recording head is arranged in order of steps.
FIG. 9 is a schematic perspective view illustrating a main part of an example of an ink jet printer on which a liquid discharge head can be mounted.
FIG. 10 is a schematic perspective view illustrating an example of an ink jet cartridge including a liquid discharge head.
FIG. 11 is a schematic perspective view schematically illustrating a main part of an example of a liquid discharge head.
FIG. 12 is a conceptual diagram in which a part of an example of a liquid discharge head is extracted.
13 is an enlarged view of the discharge port portion shown in FIG. 12. FIG.
14 is a schematic diagram illustrating an ink adhesion state at a discharge port portion illustrated in FIG. 13;
15 is a schematic diagram of a main part in FIG. 12. FIG.
16 is a schematic cross-sectional view for explaining the liquid discharge operation of the liquid discharge head over time corresponding to the XY perspective cross-sectional shape in FIG. 15 together with FIGS. 17 to 23. FIG.
17 is a schematic cross-sectional view for explaining the liquid discharge operation of the liquid discharge head over time corresponding to FIGS. 16 and 18 to 23, corresponding to the XY perspective cross-sectional shape in FIG.
18 is a schematic cross-sectional view for explaining the liquid discharge operation of the liquid discharge head over time corresponding to the XY perspective cross-sectional shape in FIG. 15 together with FIGS. 16, 17 and 19 to 23. FIG.
FIG. 19 is a schematic cross-sectional view corresponding to the XY perspective cross-sectional shape in FIG. 15 for explaining the liquid discharge operation of the liquid discharge head over time together with FIGS.
FIG. 20 is a schematic cross-sectional view for explaining the liquid discharge operation of the liquid discharge head with time corresponding to FIGS. 16 to 19 and FIGS.
FIG. 21 is a schematic cross-sectional view for explaining the liquid discharge operation of the liquid discharge head over time in conjunction with FIGS. 16 to 20, 22 and 23 corresponding to the XY perspective cross-sectional shape in FIG.
22 is a schematic cross-sectional view corresponding to the XY perspective cross-sectional shape in FIG. 15 for explaining the liquid discharge operation of the liquid discharge head over time together with FIGS. 16 to 21 and FIG.
FIG. 23 is a schematic cross-sectional view for explaining the liquid discharge operation of the liquid discharge head over time corresponding to the XY perspective cross-sectional shape in FIG. 15 together with FIGS.
FIG. 24 is a first example of a schematic cross-sectional view for explaining a head having a configuration that easily exhibits the effects of the present invention;
FIG. 25 is a second example of a schematic cross-sectional view for explaining a head having a configuration that easily exhibits the effects of the present invention;
FIG. 26 is a third example of a schematic cross-sectional view for explaining a head having a configuration that easily exhibits the effects of the present invention;
FIG. 27 is a schematic diagram for explaining a mechanism that exerts the effect of the present invention.
FIG. 28 is a conceptual diagram for explaining the difference in hydration between sodium ions and potassium ions.
FIG. 29 is a schematic perspective view of an ink jet recording apparatus 600 which is an example of a liquid ejecting apparatus to which the liquid ejecting head of the present invention can be attached and applied.
[Explanation of symbols]
1 Substrate
2 Ink discharge energy generating element
3 openings
4 Dissolvable resin layer
5 Coating resin layer
6 Mask
7 Ink supply member
8 Ink outlet
9 Ink flow path
13 heads
14 ink groove
15 Heating element substrate
16 protective layer
17-1, 17-2 electrodes
18 Heating resistor layer
19 Thermal storage layer
20 substrates
21 ink
22 Discharge orifice (fine hole)
23 Meniscus
24 ink droplets
25 material to be recorded
26 multi nozzle
27 glass plate
28 heating head
40 ink bag
42 plugs
44 ink absorber
45 ink cartridge
51 Paper feeder
52 paper feed roller
53 Paper discharge roller
61 blade
62 caps
63 ink absorber
64 discharge recovery section
65 recording head
66 carriage
67 guide shaft
68 motor
69 belt
70 recording units
71 head
72 Air communication port
80 ink flow path
81 orifice plate
82 diaphragm
83 Piezoelectric element
84 substrates
85 outlet
251 Discharge energy generator
252 outlet
253 supply port
254 substrates
255 outlet plate
261 coating resin layer
262 Discharge energy generator
263 projections
600 inkjet recording device
601 inkjet head cartridge
602 drive motor
603, 604 driving force transmission gear
605 lead screw
606 spiral groove
607 carriage
607a lever
608 Guide
609 platen roller
610 paper holding plate
611, 612 photocoupler
613 support member
614 cap member
615 ink suction means
616 Cap opening
617 cleaning blade
618 Moving member
619 body support
620 (Start suction) lever
621 cam
832: Discharge port
832a: Starting part
832b: Prone
931: Electrothermal conversion element (heater, ink discharge energy generating element)
933: Ink supply port (opening)
934: Board
935: Orifice plate (discharge port plate)
935a: Discharge port surface
936: Ink channel wall
936a: Bulkhead
940: Discharge port
1337: Foaming chamber
1338: Liquid flow path
1141: Groove
1141a: Top
100: Inkjet recording head
101: Bubble
102: Meniscus
1001: Liquid tank
1006: Movement drive unit
1008: Casing
1010: Recording section
1010a: Carriage member
1012: Cartridge
1012Y, M, C, B: Inkjet cartridge
1016: Belt
1018: Motor
1020: Drive unit
1022a, 1022b: Roller unit
1024a, 1024b: Roller unit
1026: Recovery unit
1026a, 1026b: Pulley
1028: Paper
1030: Conveyor
2701: Carbon black
2703: Water molecule
2705: Counter ion
2707: Potassium ion
2709: Sodium ion
C: Wet ink
F_M: Meniscus backward direction
F_C: Meniscus backward direction
G: Center of gravity
I: Ink
Ia: Main droplet (liquid, ink)
Ib, Ic: Liquid (ink)
Id: Ink adhering to the groove (ink in the groove)
Ie: Ink remaining in the liquid flow path
L: Line from the liquid chamber (ink supply port) to the discharge port
N₁: Width of foaming chamber
N₂: Length of foaming chamber
O: Center of discharge port
P ': Recording material
P: Paper transport direction
R: Belt rotation direction
S: Direction substantially perpendicular to the paper transport direction
T₁: Discharge port dimension
w: width of bulkhead

Claims (23)

The surface of the carbon black includes a coloring material containing at least one self-dispersing carbon black in which at least one hydrophilic group is bonded via another atomic group, and an aqueous medium. An ink- jet ink comprising 0.6% or more of potassium ions and having a density of the hydrophilic group of 1.8 μmol / m ² or more. The inkjet ink according to claim 1, wherein the hydrophilic group is at least one selected from those listed below.
-COOM, -SO ₃ M, -PO ₃ HM, -PO ₃ M ₂
(However, M in the formula represents a hydrogen atom, an alkali metal, ammonium or organic ammonium.) The inkjet ink according to claim 1, wherein the potassium ions are present as a counter for the hydrophilic group of the carbon black. The inkjet ink according to claim 1, wherein the potassium ion is derived from potassium hydroxide. The inkjet ink according to claim 1, wherein the ink has a pH of 7 or more and 10 or less. Monovalent inkjet ink according to any one of claims 1 to 5 the total amount of cations is not more than 0.05 mol / L or more 1 mol / L in the ink. The inkjet ink according to claim 6, wherein the monovalent cation ion includes at least one selected from alkali metal ions, ammonium ions, and organic ammonium ions together with potassium ions. The inkjet ink according to claim 6 or 7, wherein the content of the monovalent cation ion is 0.1 mol / L or more and 0.5 mol / L or less with respect to the total amount of the aqueous pigment ink. A recording unit comprising: an ink storage portion that stores ink; and a recording head that applies energy to the ink and causes the ink to be ejected as ink droplets, wherein the ink is any one of claims 1 to 8 . A recording unit comprising the ink according to claim 1. The recording unit according to claim 9 , wherein the recording head is a recording head whose discharge amount per dot is 40 ng or less. The recording head, a recording unit according to claim 9 or 1 0, which is a recording head having a portion where the ink flow resistance of the ink flow path is greatly changed. The recording head according to any one of claims 9 to 11, wherein a heater is disposed in the ink flow path as means for applying energy to the ink, and the heater is directly opposed to the ink ejection port. Recording unit. The recording unit according to any one of claims 9 to 11, wherein the recording head has a portion where a main flow direction of the ink changes by at least 90 ° before reaching a portion where the ink contacts the heater. An ink cartridge comprising an ink containing portion for containing ink, wherein the ink is the ink according to any one of claims 1 to 8 . Image recording apparatus characterized in that it comprises a recording unit according to Izu Re one of claims 9-1 3. An image recording method comprising a step of applying energy to the ink, causing the ink to be ejected from a recording head and adhering to the recording medium, wherein the ink is the ink according to any one of claims 1 to 8. Image recording method. Image recording method characterized by comprising the step of forming an image on a recording material using an image recording apparatus according to claim 1 5. 9. A method of reducing adhesion of a recording head, wherein the ink according to claim 1 is used when energy is applied to the ink and the ink is ejected from the recording head. 9. A combination of an ink containing at least one color material selected from cyan, magenta, yellow, red, green and blue color materials and the ink according to any one of claims 1 to 8. An ink set characterized by   A method for alleviating sticking of a recording head in an ink jet recording method including a step of discharging ink using an ink jet recording head provided with an ink discharge port at a position facing an ink discharge pressure generating element, A method of reducing adhesion, wherein the ink according to claim 9 is used. A method for alleviating sticking of the recording head in an ink jet recording method comprising a step of ejecting ink using an ink jet recording head having a portion in which the flow resistance of the liquid greatly changes in the ink flow path, fixing relaxation method which comprises using the ink according to any one of claims 1 to 8 as. Site flow resistance of the liquid is greatly changed is, the flow direction of the liquid, sticking relaxation method of claim 2 1, wherein a portion for changing more than 90 °. A method for improving intermittent ejection in an ink jet recording method, comprising the step of applying energy to the ink and repeating the step of ejecting the ink from the recording head by the ink jet method at a predetermined time interval, wherein the ink is claim 1 . 8. A method for improving intermittent ejection characteristics, wherein the ink according to any one of 8 is used.

Images