JP4100880B2 - Ink set, ink jet recording apparatus, ink jet recording method, and second aqueous ink - Google Patents

Description

上記一般式（Ｉ）中、Ｒ₁は、置換若しくは未置換のアルコキシ基、又は置換若しくは未置換のアリール基を表し、Ｒ₂及びＲ₄は、各々独立に、水素原子又は置換若しくは未置換のアルキル基を表し、Ｒ₃は、水素原子、置換若しくは未置換のアルキル基、置換若しくは未置換のアルコキシ基、置換若しくは未置換のアリールオキシ基又はハロゲン原子を表す。Ｘ₁は、カルボキシル基若しくはその塩、又はスルホン酸基若しくはその塩を表す。ｎは１又は２を表す。
【００２６】
上記一般式（Ｉ）中のＲ₁〜Ｒ₄について、より具体的には、Ｒ₁としては、例えば、炭素数１〜４の直鎖状若しくは分岐鎖状のアルコキシ基や置換若しくは未置換のフェニル基等が挙げられる。ここで、フェニル基の置換基としては、例えば、メチル基、ヒドロキシル基、ニトロ基、スルホン酸基若しくはその塩、カルボキシル基若しくはその塩又はハロゲン原子（フッ素、塩素、臭素等）等が挙げられる。Ｒ₂としては、例えば、水素原子、炭素数１〜４の直鎖状若しくは分岐鎖状の低級アルキル基等が挙げられ、Ｒ₃としては、例えば、水素原子、炭素数１〜４の直鎖状若しくは分岐鎖状のアルキル基、炭素数１〜４の直鎖状若しくは分岐鎖状のアルコキシ基、さらにはアリールオキシ基として、例えばフェノキシ基等が挙げられる。アリールオキシ基を構成するアリール基は、例えば炭素数１〜１０の直鎖状若しくは分岐鎖状のアルキル基、スルホン酸基若しくはその塩、カルボキシル基若しくはその塩等で置換されていても良い。更に、Ｒ₄としては、例えば、水素原子、炭素数１〜４の直鎖状若しくは分岐鎖状の低級アルキル基等が挙げられる。又、Ｘ₁について詳述すると、Ｘ₁としては、例えば、−ＣＯＯＭや−ＳＯ₃Ｍ［但し、Ｍは、水素原子、アルカリ金属（例えば、Ｌｉ、Ｎａ等）、アンモニウム（ＮＨ₄）、有機アンモニウム（Ｎ（Ｒ₈）₄）］等が挙げられる。ここで、Ｒ₈としては、メチル基又はエチル基等が挙げられる。
【００２７】
又、上記した色材に共に使用することのできる第１のインクに追加して添加する染料としては、キサンテン系の染料、例えば、Ｃ．Ｉ．アシッドレッド５２やＣ．Ｉ．アシッドレッド２８９等から選ばれる少なくとも１つの染料、下記一般式（II）及び（III）から選ばれる少なくとも１つの染料、若しくはそれらの両方が挙げられる。特に、第１のインク中の色材として、上記した一般式（Ｉ）で示される染料と下記一般式（II）で示される染料とＣ．Ｉ．アシッドレッド２８９とを組み合わせた場合は、当該インクによる画像のマゼンタの色調は特に優れたものとなり、カラーバランスの変化抑制効果とあいまって、写真調のカラー画像の形成のためには特に好ましいものである。
【００２８】

上記一般式（II）中、Ａｒ₁は置換若しくは未置換のフェニル基、又は置換若しくは未置換のナフチル基を表し、Ａｒ₂は、アセチル基、ベンゾイル基、１，３，５−トリアジニル基、ＳＯ₂−Ｃ₆Ｈ₅基又はＳＯ₂−Ｃ₆Ｈ₄−ＣＨ₃基のいずれかを表す。Ｍは、スルホン酸基の対イオンであり、水素原子、アルカリ金属（例えば、Ｌｉ、Ｎａ等）、アンモニウム（ＮＨ₄）及び有機アンモニウム（Ｎ（Ｒ₉）₄）のいずれかを表す。ここでＲ₉としては、メチル基またはエチル基等が挙げられる。
【００２９】
上記Ａｒ₁のフェニル基やナフチル基は、例えば、カルボキシル基若しくはその塩、スルホン酸基若しくはその塩、炭素数１〜４の直鎖状若しくは分岐鎖状のアルキル基、ハロゲン原子（フッ素、塩素、臭素等）、炭素数１〜４のアルコキシ基、フェノキシ基等のアリールオキシ基等から選ばれる１つ又は２つ以上の基や原子で置換されていてもよい。また上記Ａｒ₂が、ベンゾイル基若しくは１，３，５−トリアジニル基である場合には、ベンゼン環若しくは１，３，５−トリアジン環中の少なくとも１つの水素原子が、カルボキシル基やその塩、ハロゲン原子（フッ素、塩素、臭素等）、１〜３級アミノ基、アルコキシ基、水酸基等で置換されていてもよい。
【００３０】

上記一般式（III）中、Ａｒ₃及びＡｒ₄は、各々独立に、置換若しくは未置換のフェニル基、又は置換若しくは未置換のナフチル基を表す。フェニル基やナフチル基の置換基としては、例えば、炭素数１〜４の直鎖状若しくは分岐鎖状のアルキル基、炭素数１〜４の直鎖状若しくは分岐鎖状のアルコキシル基、ヒドロキシル基、カルボキシル基若しくはその塩、スルホン酸基若しくはその塩、ハロゲン原子（フッ素、塩素、臭素等）等が挙げられ、Ａｒ₃及びＡｒ₄の少なくとも１つはカルボキシル基若しくはその塩、或いはスルホン酸基若しくはその塩の置換基を有す。Ｍは、スルホン酸基の対イオンであり、水素原子、アルカリ金属（例えば、Ｌｉ、Ｎａ等）、アンモニウム（ＮＨ₄）及び有機アンモニウム（Ｎ（Ｒ₁₀）₄）のいずれかを表す。ここで、Ｒ₁₀としては、メチル基又はエチル基等が挙げられる。Ｒ₅は、１，３，５−トリアジンジイル基を表し、１，３，５−トリアジン環中の少なくとも１つの水素原子が、カルボキシル基やその塩、ハロゲン原子（フッ素、塩素、臭素等）、１〜３級アミノ基、アルコキシ基、水酸基等で置換されていてもよい。
Ｒ₆及びＲ₇は、独立に、水素原子、置換若しくは未置換のアルキル基、置換若しくは未置換のアルケニル基置換若しくは未置換のアラルキル基又はＮと共にペルヒドロキシアジン環を形成するに必要な原子群を表し、Ｌは、２価の有機連結基を表す。Ｒ₆及びＲ₇について、より具体的には、例えば、炭素数１〜６の直鎖上若しくは分岐鎖状のアルキル基や炭素数１〜４の直鎖上若しくは分岐鎖状のアルケニル基やベンジル基等があげられる。ここで、アルキル基、アルケニル基及びベンジル基の置換基としては、ヒドロキシル基、カルボキシル基若しくはその塩、スルホン酸基若しくはその塩等が挙げられる。
【００３１】
以下に、本発明において好適に用いられる上記一般式（Ｉ）で示される第１の色材の具体例として、例示化合物Ｉ−１〜Ｉ−７を示すが、本発明はこれらの色材に限定されるものではない。又、これらの色材を同時に２種類以上用いてもよい。以下、例示化合物Ｉ−１〜Ｉ−７中のＭは、Ｈ、Ｌｉ、Ｎａ、ＮＨ₄及びＮ(Ｒ₈)₄のいずれかを表す。
【００３２】

【００３３】

【００３４】

【００３５】
本発明に好適に用いられる色材である前記一般式（II）で表される化合物としては、例えば、Ｃ．Ｉ．Ｒｅａｃｔｉｖｅ Ｒｅｄ １８０や、以下に挙げる構造を有する例示化合物II−８〜II−１３、更には、特開平８−７３７９１号公報、特開平１１−２０９６７３号公報等に記載されている構造の化合物が挙げられる。以下、例示化合物II−８〜II−１３中のＭは、Ｈ、Ｌｉ、Ｎａ、ＮＨ₄及びＮ（Ｒ₉）₄のいずれかを表す。
【００３６】

【００３７】

【００３８】

【００３９】
本発明において、好適な色材として用いられる一般式（III）の化合物としては、下記構造を有する例示化合物III−１４〜III−２２が挙げられる。以下、例示化合物III−１４〜III−２２中のＭは、Ｈ、Ｌｉ、Ｎａ、ＮＨ₄及びＮ（Ｒ₁₀）₄のいずれかを表す。
【００４０】

【００４１】

【００４２】

【００４３】

【００４４】

【００４５】
マゼンタ系の第１のインク中における一般式（Ｉ）で表される色材と、一般式（Ｉ）以外の色材との質量比は、鮮明な色調と高い画像濃度と更に優れた耐光性が得られるという効果を考慮すると、９５：５〜２０：８０の範囲とすることが好ましい。
ところで、本発明において使用する各インクは、そのインクの色調に関わらず、各インクにおける全色材の含有量が、色材濃度の高い第１のインクの濃色インクおいては、インク全量に対して１．０〜１５．０質量％、色材濃度の低い第２のインクの淡色インクおいては、インク全量に対して０．１〜５．０質量％の範囲のものを用いることが好ましい。
【００４６】
（水性媒体）
本発明で使用する各インクは、上記に挙げたような色材と水性媒体とを有する水性インクである。この際に使用する水性媒体としては、水、又は水と水溶性有機溶剤との混合媒体に含まれる水溶性有機溶剤は、水溶性を示すものであれば特に制限はなく、アルコール、多価アルコール、ポリグリコール、グリコールエーテル、含窒素極性溶媒、含硫黄極性溶媒等が挙げられる。これらの水溶性有機溶剤はインクの保湿性維持や色材の溶解性向上、インクの記録紙への効果的な浸透等を考慮すると、水溶性有機溶剤の含有量は、インク全体の１〜４０質量％の範囲とすることが好ましく、より好ましくは３〜３０質量％の範囲とする。又、色材である染料のインク中における溶解性が良好であり、安定したインク吐出のための粘度を有し、且つ、ノズル先端における目詰まりを生じさせないために、インク中の水の含有量は３０〜９５質量％の範囲が好ましい。
【００４７】
（ｐＨ）
本発明で使用する各インクのｐＨは、色材の溶解度性を満足するものであれば特に限定されるものではない。但し、安全性等の面を考慮すると、ｐＨ４．０〜１１．０の範囲内のものが好ましい。
【００４８】
（添加剤）
本発明で使用する各インクを作製する場合には、インクの保湿性維持のために、尿素、尿素誘導体、トリメチロールプロパン等の保湿性固形分もインク成分として用いてもよい。尿素、尿素誘導体、トリメチロールプロパン等、保湿性固形分のインク中の含有量は、一般には、インクに対して０．１〜２０．０質量％の範囲が好ましく、より好ましくは３．０〜１０．０質量％の範囲である。更に本発明で使用する各インクには、上記成分以外にも、必要に応じて、界面活性剤、ｐＨ調整剤、防錆剤、防腐剤、防カビ剤、酸化防止剤、還元防止剤、蒸発促進剤、キレート化剤、水溶性ポリマー等、種々の添加剤を含有させてもよい。
以上説明した本発明のインクセットの各実施態様にかかるインクは、熱エネルギーの作用により液滴を吐出させて記録を行うインクジェット記録方式にとりわけ好適に用いられるが、他のインクジェット記録方法や一般の筆記用具としても使用できることはいうまでもない。
【００４９】
（記録装置、インクカートリッジ、記録ユニット）
ところで、本発明のインクセットを用いて記録を行うのに好適な記録装置としては、記録ヘッドの室内のインクに記録信号に対応した熱エネルギーを与え、該エネルギーによりオリフィスより液滴を吐出させる本発明のインクジェット記録装置が挙げられる。
【００５０】
その主要部である記録ヘッドの構成例を、図１〜図３に示した。図１は、インクの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線での断面図である。ヘッド１３は、インクを通す溝１４を有するガラス、セラミックス、又はプラスチック板等と、感熱記録に用いられる発熱抵抗体を有する発熱ヘッド１５（図ではヘッドが示されているが、これに限定されるものではない）とを接着して得られる。発熱ヘッド１５は、酸化シリコン等で形成される保護膜１６、アルミニウム電極１７−１及び１７−２、ニクロム等で形成される発熱抵抗体層１８、畜熱層１９、アルミナ等の放熱性のよい基板２０より成っている。インク２１は、吐出オリフィス（微細孔）２２まで満たされており、圧力Ｐによりメニスカス２３を形成している。
【００５１】
ここで電極１７−１及び１７−２に電気信号が加わると、発熱ヘッド１５ｎで示される領域が急激に発熱し、ここに接しているインク２１に気泡が発生する。その圧力でメニスカスが吐出し、オリフィス２２より記録液滴２４となり、被記録材（記録媒体）２５に向かって飛翔する。図３には図１に示したノズルを多数並べた、マルチ溝２６を有する記録ヘッドの概略図を示す。該記録ヘッドは多数の流路を有するガラス板等２７と図１において説明したヘッドと同様の発熱ヘッド２８を密着して作られる。
【００５２】
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した。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されて、固定端となりカンチレバーの形態をなす。ブレード６１は、記録ヘッドによる記録領域に隣接した位置に配設され、又、図４に示した例の場合は、記録ヘッドの移動経路中に突出した形態で保持される。６２はキャップであり、ブレード６１に隣接するホームポジションに配設され、記録ヘッドの移動方向と垂直な方向に移動して、吐出面と当接しキャッピングを行う構成を具える。更に、図４中の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、吸収体６３によって吐出回復部６４が構成され、ブレード６１及び吸収体６３によってインク吐出口面の水分、塵やほこり等の除去が行われる。
【００５３】
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と摺動可能に係合し、キャリッジ６６の一部はモータ６８（不図示）によって駆動されるベルト６９と接続している。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給紙部、５２は不図示のモータにより駆動される紙送りローラである。これらの構成によって記録ヘッドの吐出口面と対向する位置へ被記録材が給紙され、記録が進行するにつれて、排紙ローラ５３を配した排紙部へ排紙される。
【００５４】
上記構成において、記録ヘッド６５が記録終了等でホームポジションに戻る際、ヘッド回復部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。この結果、記録ヘッド６５の吐出口面がワイピングされる。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う場合、キャップ６２は記録ヘッドの移動経路中へ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。
上記した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為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われる。
【００５５】
図５は、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の一例を示す断面図である。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できる。４４は廃インクを受容するインク吸収体である。本発明においては、このようなインクカートリッジのインク収容部に、本発明のインクセットを構成する第１のインク及び第２のインクを各々充填し、各々のインクカートリッジを、各々のインクを吐出させるためのインクジェット記録ヘッドを備えたインクジェットプリンタのヘッドに装着して画像形成を行なうことで、本発明の優れた効果の達成を図る。
【００５６】
又、本発明のインクセットを構成する第１のインク及び第２のインクが夫々充填された本発明のカートリッジの他の例としては、例えば、図７に示したような、第１のインクと第２のインクとを各々個別に収納している２つの収容部７０３及び７０５を備え、図８に示したように、各々のインクを個別に吐出させるためのインクジェットヘッドに対して着脱可能に構成されているカートリッジ７０１が挙げられる。具体的には、図７において、７０１がカートリッジであり、７０３は第１のインクを収容している第１のインク収容部、７０５が第２のインクを収容している第２のインク収容部である。そして、図７に示したような構成のカートリッジは、図８に示すように、第１のインク及び第２のインクの色材濃度の異なる２種類のインク各々を吐出せしめる記録ヘッド８０１に着脱可能に構成されてなると共に、該カートリッジ７０１を記録ヘッド８０１に装着した状態では、２種類の色材濃度の異なるインクが、記録ヘッド８０１に供給されるように構成されている。
【００５７】
本発明のインクジェット記録装置としては、上記の如き記録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に示すように、それらが一体になったもの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って、この中には、本発明のインクセットを構成する各インクが収容されているインク収容部、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、複数の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。７２は、記録ユニット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で示す記録ヘッド６５に代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。
【００５８】
更に、本発明の他の実施態様としては、本発明のインクセットを構成する第１のインクと第２のインクとを、１個のインクタンク内の各々のインク収納部に収納し、且つ、各々のインクを吐出させるための記録ヘッドを一体的に備えた記録ユニット、具体的には、例えば、図９に示すように第１のインクを収容部９０１に、又、第２のインクを収納部９０３に収納し、更に各々のインクを個別に吐出させることができるようにインク流路を分けて構成した記録ヘッド９０５を備えているような記録ユニット９０７が挙げられる。
尚、上記では、本発明に使用される記録装置として、インクに熱エネルギーを作用させてインク液滴を吐出するインクジェット記録装置を例に挙げたが、その他、圧電素子を使用するピエゾ方式のインクジェット記録装置でも同様に利用することができる。
【００５９】
次に、本発明に好適に使用できる記録装置及び記録ヘッドの他の具体例について説明する。
図１０は、本発明に好適な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、及び、この液体吐出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。図１０に示した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被記録材としての用紙１０２８を、図１０に示す矢印Ｐで示す方向に間欠的に搬送するための搬送装置１０３０と、該搬送装置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、ガイド軸１０１４に沿って往復運動せしめられる記録部１０１０と、記録部１０１０を往復運動させるための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。
【００６０】
上記搬送装置１０３０は、互いに略平行に対向配置されている一対のローラユニット１０２２ａ及び１０２２ｂと、一対のローラユニット１０２４ａ及び１０２４ｂと、これらの各ローラユニットを駆動させるための駆動部１０２０とを備えている。かかる構成により、搬送装置１０３０の駆動部１０２０が作動状態とされると、用紙１０２８が、夫々のローラユニット１０２２ａ及び１０２２ｂと、ローラユニット１０２４ａ及び１０２４ｂにより狭持されて、図１０に示す矢印Ｐ方向に間欠送りで搬送されることとなる。
又、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及び１０２６ｂに巻きかけられるベルト１０１６と、ローラユニット１０２２ａ及び１０２２ｂに略平行に配置され、且つ、記録部１０１０のキャリッジ部材１０１０ａに連結されるベルト１０１６を順方向及び逆方向に駆動させるためのモータ１０１８、とを含んで構成されている。
【００６１】
そして、モータ１０１８が作動状態とされてベルト１０１６が図１０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１０の矢印Ｓ方向に所定の移動量だけ移動される。又、モータ１０１８が作動状態とされてベルト１０１６が図１０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１０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。更に、この移動駆動部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。
【００６２】
記録部１０１０には、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及び１０１２Ｂが、各色用毎に、例えば、イエロー、マゼンタ、シアン及びブラック用毎に、キャリッジ部材１０１０ａに対して夫々着脱自在に備えられている。
【００６３】
図１１に、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した。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、インク等の液体を収容するための液体タンク１００１とで主要部が構成されている。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、インク等の液体は、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１２参照）へと導かれるようになっている。図１１に示したカートリッジ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。
【００６４】
以下に、上記したような構成のインクジェットプリンタに搭載され得る液体吐出ヘッドの具体例を、更に詳しく説明する。
図１２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１３〜図１６は、図１２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。尚、電気熱変換素子を駆動するための電気的な配線等は省略している。
【００６５】
本例の液体吐出ヘッドにおいては、例えば、図１２に示されるような、ガラス、セラミックス、プラスチック或いは金属等からなる基板９３４が用いられる。このような基板の材質は、本質的なものではなく、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、及び後述する液流路、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。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）等の露光装置により形成することもできる。
【００６６】
図１２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及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が夫々１列ずつ千鳥状に、例えば、電気熱変換素子（ヒータ）の間隔が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、更に、吐出口８３２を備える吐出口プレート９３５が設けられている。
【００６７】
ここで、図１２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、スピンコート等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、更に、吐出口面（上面）９３５ａ側は、撥水処理が施されている。
【００６８】
本例では、先に説明した図１０の矢印Ｓ方向に走査しながら記録を行うシリアルタイプのヘッドを用い、例えば、１２００ｄｐｉで記録を行う。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毎に吐出を行うことになる。又、ヘッドの実例寸法の一例としては、例えば、図１３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。図中の１３３７は発泡室を示す。又、図１６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。又、インク流路壁９３６及び隔壁９３６ａの高さは１２μｍで、吐出口プレート９３５の厚さは１１μｍのものが使用できる。
【００６９】
図１２に示した、吐出口８３２を含む吐出口プレート９３５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、図１４に示したように、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、且つ、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。即ち、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１２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１１４１が形成されている（図１４参照）。
【００７０】
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１４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。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。図１５は、図１４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が、図中のＣは濡れインクである。
【００７１】
次に、上述した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１７〜図２４を用いて説明する。図１７〜図２４は、図１２〜図１６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１６に示す発泡室１３３７のＸ−Ｘ断面図である。この断面において、図１２に示した吐出口部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。図１７は、ヒータ上に膜状の気泡が生成した状態を示し、図１８〜図２４は、その後の気泡の状態を経時的に表したものである。即ち、図１８は、図１７の約１μｓ後、図１９は、図１７の約２μｓ後、図２０は、図１７の約３μｓ後、図２１は、図１７の約４μｓ後、図２２は、図１７の約５μｓ後、図２３は、図１７の約６μｓ後、図２４は図１７の約７μｓ後の状態を夫々示している。尚、以下の説明において、「落下」又は「落とし込み」、「落ち込み」とは、所謂、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のことを意味している。
【００７２】
先ず、図１７に示すように、記録信号等に基づいたヒータ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１８及び図１９に示すように、気泡１０１は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を上回るが、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。
【００７３】
次に、気泡１０１の生成から約２μｓ後の時点で、上述のように、気泡１０１は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。図２０に示すように、このメニスカス１０２もヒータ９３１側への方向に後退、即ち、落下してゆく。ここで、本例においては、先に述べたように、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１０２の後退方向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１０２の後退時のメニスカス及び主液滴（以下、液体又はインクと記述する場合がある）Ｉ_a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。
【００７４】
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２１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）Ｉ_aが、気泡１０１が大気と連通した後も慣性でヒータ９３１面方向の速度を保持しているからである。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２２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２３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。
【００７５】
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、即ち、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。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Ｉ_bが細くなってゆき、図２４に示したように、気泡１０１の生成から約７μｓ後の時点でヒータ９３１の表面の中央で液体Ｉ_bが切断され、吐出方向の速度ベクトルを保つ主液滴Ｉ_aと、ヒータ９３１の表面上に拡がった液体Ｉ_c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（ヒータ）９３１側が望ましい。
【００７６】
主液滴Ｉ_a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、被記録材の被記録面の所定位置に着弾される。又、ヒータ９３１の表面上に拡がった液体Ｉ_c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。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被記録材の被記録面が汚れるのを確実に防止することができる。尚、図１８〜２４において、Ｉはインクを、Ｉ_dは溝部に付着したインク（溝内のインク）を、又、Ｉ_eは液流路内に残存しているインクを表している。
【００７７】
上記で説明したように、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。又、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うことができることにより、高速高精細印字を実現することができる。
【００７８】
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。又、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は、例えば、日本特許登録第２７８３６４７号に記載のように、所謂エッジシュータータイプが挙げられる。
【００７９】
【実施例】
次に実施例及び比較例を挙げて本発明を更に詳しく説明する。尚、特に指定のない限り、実施例、比較例のインク成分は「質量部」を意味する。
＜実施例１〜７、比較例１〜６＞
下記のインク組成１に示した各成分に、表１又は２に示した色材を表中に示した量加え、更にイオン交換水を加えて全体量を１００部としたものを混合し、その後、０．２０μｍフィルターにて加圧濾過を行って、各々の色材濃度の異なる２種類のインクからなる実施例１〜７、比較例１〜６のインクセットを夫々作製した。
【００８０】
（インク組成１）
・グリセリン ５．０部
・尿素 ５．０部
・ジエチレングリコール １０．０部
・アセチレノールＥＨ(川研ファインケミカル社製)０．３部
・エタノール ５．０部
【００８１】

【００８２】

【００８３】
＜評価＞
上記で得られた実施例１〜７と比較例１〜６の各インクセットについて、インクセットを構成している第１及び第２のインクを夫々用いて画像を形成し、下記の方法で第１及び第２インクの耐光性、及び第１インクの発色性の評価を行なった。その際、インクジェット記録装置を使用して画像形成を行ったが、発熱素子をインク吐出のエネルギー源にするオンデマンド式インクジェットプリンタを使用して印字を行った。
【００８４】
［耐光性］
インクジェットプリンタに、色材濃度の高い濃インク（第１のインク）と、色材濃度の低い淡インク（第２のインク）とが組み合わされて構成されている上記各実施例若しくは比較例のインクセットをセットし、ＰＰＣ用紙（キヤノン製）及び光沢紙（ＰＲ−１０１；キヤノン製）の２種類の被記録材に夫々ベタ部を印字した印字物を得た。得られた夫々の印字物を２４時間自然乾燥させ、紫外線カットフィルターを装着したキセノンフェードメーターＣｉ３０００（アトラス社製）にて、槽内温度３５℃、相対湿度６０％の条件下で、照射強度６０ｋｌｕｘで１００時間曝露照射した。そして、反射濃度計マクベスＲＤ−９１８（商品名：マクベス社製）で、試験前後での印字物の各インク画像の反射濃度を測定し、試験後における濃度残存率を求めた。その時の濃色インク（第１のインク）における濃度残存率を下記基準で評価し、表３中の［１−ａ］に示した。更に、得られた濃度残存率を用い、各インクセットを構成する第１及び第２インク間の濃度残存率を比較し、そして、下記基準を用いて評価し、表３中の［１−ｂ］に示した。
【００８５】
［１−ａ］濃色インク（第１のインク）の濃度残存率
Ａ：濃色インクの濃度残存率が８０％以上
Ｂ：濃色インクの濃度残存率が６０％以上８０％未満
Ｃ：濃色インクの濃度残存率が６０％未満
【００８６】
［１−ｂ］濃色（第１）インクと淡色（第２）インクとの耐光性の比較
Ａ：淡色インクの濃度残存率が濃色インクの濃度残存率以上
Ｂ：淡色インクの濃度残存率が濃色インクの濃度残存率未満
【００８７】
［発色性］
上記で得られた実施例１〜７と比較例１〜６の各インクセットを構成しているインクのうちの濃色インク（第１インク）を夫々用いて画像を形成し、下記の方法で発色性を調べた。前記のインクジェットプリンタに、各インクセットを構成するインクの色材濃度の高い濃色インク（第１インク）をセットして、ＰＰＣ用紙（キヤノン製）及び光沢紙（ＰＲ−１０１；キヤノン製）の２種類の被記録材を用い、その各々にベタ部を印字した。得られた印字物を２４時間自然乾燥させ、その発色性を目視にて観察し、下記の基準で評価し、結果を表３中に示した。
ＡＡ：特に鮮やかな色調を有するもの。
Ａ：鮮やかな色調を有するもの。
Ｂ：ややくすみのある色調を有するもの。
【００８８】

【００８９】
更に、上記の実施例及び比較例のインクセットで形成した印刷物について、耐光性を評価するために用いた光を照射する前後の印字物を夫々目視にて対比して、各印字物について褪色の様子を観察した。この結果、実施例１〜７のインクセットを使用して形成した印字物はいずれのものも、相対的に色材濃度の高い第１のインクによる印刷部分と、相対的に色材濃度の低い第２のインクによる印刷部分は、共に顕著な褪色は認められなかった。これに対し、比較例１〜６のインクセットを使用して形成した印字物は、光を照射した後の第２インクによる印刷部分の褪色によって部分的に色調の変化がみられ、このことが試験後の印字物に対して褪色が顕著であるとの印象を与えていることがわかった。本発明のインクセットを構成する第１及び第２のインクを用いて形成した画像は、耐光劣化速度の差に起因するカラー画像の経時的なカラーバランスの変化を抑制できることがわかった。
【００９０】
【発明の効果】
以上説明したように、本発明によれば、各種の記録用紙に印字した際に優れた耐光性と鮮明な画像を提供することができるインクセット、インクジェット記録装置及びインクジェット記録方法が提供される。又、本発明によれば、形成した画像を長期間保存した場合にも、カラーバランスが崩れにくいインクジェットカラー画像を与えることのできるインクセット、インクジェット記録装置及びインクジェット記録方法が提供される。
又、本発明によれば、画像により一層の耐久性を備え、画像を長期間保存した場合にも、視覚的に劣化が認識しにくいインクジェットカラー画像を形成することのできるインクジェット記録方法及びそれに用いるインクジェット記録装置、記録ユニット及びインクカートリッジが提供される。
更に、本発明によれば、画像を長期間保存した場合にも、特に、マゼンタカラー画像の劣化に起因する視覚的なカラーバランスの変化を抑えることのできるマゼンタ色のインクセット、インクジェット記録装置及びインクジェット記録方法が提供される。更に、本発明によれば、マゼンタカラー画像の劣化等に起因する画像劣化が認識しにくい優れたインクジェットカラー画像の形成に極めて有効に用いることのできる記録ユニット、インクカートリッジが提供される。
【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部の縦断面図である。
【図２】インクジェット記録装置のヘッド部の横断面図である。
【図３】インクジェット記録装置のヘッド部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斜視図である。
【図５】インクカートリッジの縦断面図である。
【図６】記録ユニットの斜視図である。
【図７】本発明のインクカートリッジの一実施態様を示す概略図である。
【図８】図７のインクカートリッジを装着した記録ヘッドの概略図である。
【図９】本発明の記録ユニットの一実施態様を示す概略図である。
【図１０】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１１】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１２】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１３】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１４】図１３に示した吐出口の部分の拡大図である。
【図１５】図１４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１６】図１３における主要部の模式図である。
【図１７】図１６中のＸ−Ｘ矢視断面形状に対応し、図１８〜図２４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１６中のＸ−Ｘ矢視断面形状に対応し、図１７及び図１９〜図２４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１６中のＸ−Ｘ矢視断面形状に対応し、図１７、図１８及び図２０〜図２４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１６中のＸ−Ｘ矢視断面形状に対応し、図１７〜図１９及び図２１〜図２４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１６中のＸ−Ｘ矢視断面形状に対応し、図１７〜図２０及び図２２〜図２４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１６中のＸ−Ｘ矢視断面形状に対応し、図１７〜図２１、図２３及び図２４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１６中のＸ−Ｘ矢視断面形状に対応し、図１７〜図２２及び図２４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】図１６中のＸ−Ｘ矢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。
【符号の説明】
１３：ヘッド
１４：溝
１５：発熱ヘッド
１６：保護膜
１７−１、１７−２：アルミニウム電極
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
２３：メニスカス
２４：記録液滴
２５：被記録材
２６：マルチ溝
２７：ガラス板等
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：ワイピング部材（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
６９：ベルト
７０：記録ユニット
７１：ヘッド部
７２：大気連通口
１００：インクジェット記録ヘッド
１０１：気泡
１０２：メニスカス
７０１：カートリッジ
７０３：第一のインク収容部
７０５：第二のインク収容部
８０１：記録ヘッド
８３２：吐出口
８３２ａ：起部
８３２ｂ：伏部
９０１：第一のインク収容部
９０３：第二のインク収容部
９０５：記録ヘッド
９０７：記録ユニット
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
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
１０１４：ガイド軸
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
１１４１：溝
１１４１ａ：頂部
１３３７：発泡室
１３３８：液流路
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
Ｉ_a：主液滴（液体、インク）
Ｉ_b、Ｉ_c：液体（インク）
Ｉ_d：溝部に付着したインク（溝内のインク）
Ｉ_e：液流路内に残存しているインク
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：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
ｗ：隔壁の幅寸法[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an ink set, in particular, an ink set, an ink jet recording apparatus, and an ink jet recording method that can be suitably used for ink jet recording in which recording is performed on a recording medium by discharging from an orifice according to a recording signalLawAnd a second water-based ink.
[0002]
[Prior art]
Conventionally, for color recording using an ink jet recording method, for example, water-based inks in which dyes having respective color tones are dissolved in a water-soluble medium are used. For these inks, for example, it is desired that the ink jet recording characteristics as listed in the following (1) to (10) can be achieved at the highest possible level.
(1) To provide an image with sufficient density
(2) Good drying on the recording material
(3) There is no blur in the recorded image.
(4) The recorded image does not flow out even when it comes into contact with water, alcohol, etc.
(5) The recorded image has excellent light resistance.
(6) No clogging at the nozzle tip
(7) There will be no inconvenience such as blurring of recorded images when continuously printing or when recording is started after being left for a long time.
(8) The ink is stable during storage.
(9) During use, no problem will occur even if it comes into contact with the members constituting the recording means.
(10) Excellent heat resistance and does not adversely affect the thermal energy generating element.
[0003]
Further, in recent years, colorization of inkjet recordings has progressed, and realization of higher definition and higher quality images has been demanded. In response to these requirements, a color image with a wide color reproduction range is realized by selecting a color material with excellent color developability, and the dot size of the image is reduced by making the ink droplets into small droplets. Aiming to achieve fine image quality. Furthermore, by using two or more kinds of inks having the same color tones different in color material density, these inks are selectively used corresponding to the shaded portion of the image to be formed, and by controlling various ink application processes, It has become possible to obtain an even smoother image. In recent years, through the above-described techniques, high-quality inkjet recording images comparable to silver salt photography have been obtained by the inkjet recording method.
[0004]
However, even if a high-quality inkjet recording image comparable to silver halide photography can be formed by the above-mentioned technology, depending on the environment at the time of image storage, the color balance may be lost and visually deteriorated impression In some cases, there is a problem in durability of the image. For this reason, not only high image quality but also more excellent durability, specifically, for example, an ink jet recorded image with less discoloration even after long-term storage has been demanded. ing.
[0005]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide an ink set capable of providing an ink-jet color image in which the color balance is not easily lost even when the image is stored for a long period of time.
Another object of the present invention is to provide an ink jet recording method capable of forming an ink jet color image which is further durable and is difficult to visually perceive deterioration even when the image is stored for a long period of time. An object of the present invention is to provide an ink jet recording apparatus used therefor.
Another object of the present invention is to provide a magenta color ink set capable of suppressing a change in visual color balance caused by deterioration of a magenta color image even when the image is stored for a long period of time. There is.
Furthermore, another object of the present invention is to provide a recording unit and an ink cartridge that can be used very effectively for forming an inkjet color image in which image degradation caused by degradation of a magenta color image is difficult to recognize.
[0006]
[Means for Solving the Problems]
  The above object is achieved by the present invention described below. That is, one embodiment of the ink set of the present invention is an ink set having the first and second aqueous inks having the same color tone, and each of the first and second inks has at least a common dye color. An image obtained by the second ink, the second ink having a lower colorant concentration than the first ink.The residual ratio of the reflection density of the second ink image after being left under a predetermined condition is equal to the reflection density of the first ink image after the image obtained with the first ink is left under the same conditions as described above. In order to satisfy the relationship of the residual ratio of the reflection density of the first ink image and the second ink image, the first ink and the second ink each include at least a common dye as a coloring material. The first ink further contains another dye as a coloring material.It is characterized by.
  SoThus, by adopting the above-described aspect, it is possible to obtain a color image with little color balance collapse even after long-term storage.
[0007]
  Also, an embodiment of the ink jet recording apparatus capable of achieving the above object includes an ink containing portion containing first and second aqueous inks having the same color tone, and a head portion for discharging the ink. The first and second inks each include at least a common dye as a color material, and the second ink has a color material concentration lower than that of the first ink. And an image obtained by the second inkThe residual ratio of the reflection density of the second ink image after being left under a predetermined condition is equal to the reflection density of the first ink image after the image obtained with the first ink is left under the same conditions as described above. In order to satisfy the relationship of the residual ratio of the reflection density of the first ink image and the second ink image, the first ink and the second ink each include at least a common dye as a coloring material. The first ink further contains another dye as a coloring material.It is characterized by.
[0008]
  Furthermore, one embodiment of the ink jet recording method capable of achieving the above object is a first aqueous ink having the same color tone, including at least a common dye as a color material, and having different color material concentrations. And a second water-based ink each having a step of applying to the recording medium, wherein the second ink has a lower color material concentration than the first ink, and the second ink Images obtained byThe residual ratio of the reflection density of the second ink image after being left under a predetermined condition is equal to the reflection density of the first ink image after the image obtained with the first ink is left under the same conditions as described above. In order to satisfy the relationship of the residual ratio of the reflection density of the first ink image and the second ink image, the first ink and the second ink each include at least a common dye as a coloring material. The first ink further contains another dye as a coloring material.It is characterized by.
  SoBy adopting the above-described aspect, it is possible to obtain an ink-jet color image with little color balance disruption even after long-term storage.
[0015]
  One embodiment of the second water-based ink that can achieve the above object is a second water-based ink used in an ink set having the first and second water-based inks having the same color tone, In the second aqueous ink containing a dye common to the dye as the color material contained in one water-based ink as the color material and having a color material concentration lower than that of the first ink, the ink is obtained by the second ink. imageThe residual ratio of the reflection density of the second ink image after being left under a predetermined condition is equal to the reflection density of the first ink image after the image obtained with the first ink is left under the same conditions as described above. In order to satisfy the relationship of the residual ratio of the reflection density of the first ink image and the second ink image, the first ink and the second ink each include at least a common dye as a coloring material. The first ink further contains another dye as a coloring material.It is characterized by.
  SoIn the present invention, by adopting the above-described aspects, it is possible to form an ink jet color image having excellent durability in which deterioration with time due to deterioration of an ink image having a magenta color is suppressed. It becomes.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to preferred embodiments.
In the above-described conventional technical background, the present inventors have repeatedly studied to form an inkjet color image having superior durability. Through the study, the present inventors proceeded more rapidly in the light-colored portion where the color material density is low, that is, in an image formed with two types of inks having the same color tone and different densities. Even when the same color material is used for the light resistance of the ink, the image portion formed using light ink becomes more fading, the color balance of the entire image is lost, and the image is further visually deteriorated. It has come to the knowledge that it tends to give an impression. It was also found that this tendency is particularly remarkable in the image portion where magenta dark and light inks are involved.
[0017]
Further, when creating a photo-tone image, in order to obtain smooth gradation, there is a tendency to form an image using a large amount of light color ink in the intermediate color portion. Further, as one method for maintaining the continuity of the color tone between the dark color portion and the light color portion, at least one kind of common color material is used for each of the dark color ink and the light color ink having different color material concentrations. It can be included. On the other hand, in order to improve the durability of the inkjet recording image under the above-described circumstances, the present inventors have endured the image by each of the dark color ink and the light color ink containing a common color material. In other words, in other words, how to set the combination of dark ink and light ink is extremely important, and in a photo-like inkjet recording image in which visual image deterioration is particularly conspicuous, In order to further improve the durability, it has been recognized that it is particularly important to find an optimal combination of dark and light inks. The present invention has been made based on such recognition.
[0018]
JP-A-2-127482 discloses a conventionally known recording method for providing an image having excellent light fastness and sharpness using inks having different densities. In Japanese Patent Application Laid-Open No. 2-127482, dyes different in dark ink and light ink are used. Is disclosed. However, in these, in consideration of the continuity of the color tone between the dark color portion and the light color portion, the present invention presents a technical problem peculiar to the case where a common color material is contained in the dark color ink and the light color ink. No solution to the problem is presented. According to the study by the present inventors, the magenta color material having an anthrapyridone skeleton represented by the general formula (I) used in one embodiment of the present invention is light-colored in JP-A-2-127482. It has a light resistance much higher than that of the dye used in the ink, and it has been found that even when used in the dark ink, an image having both excellent light resistance and sharpness can be provided.
[0019]
JP-A-59-74173, JP-A-2-16171 and the like disclose a magenta water-based dye ink using a dye having an anthrapyridone skeleton, and the dye has excellent light resistance. In addition, JP-A-57-197191 and JP-A-2000-169776 disclose an ink-jet color print system using a magenta aqueous dye ink containing a dye having an anthrapyridone skeleton. Yes. However, these inventions do not disclose any mixing of an anthrapyridone-based magenta dye and other magenta dyes, and further improve the light resistance of an image formed by a mixed ink using a plurality of inks. The effect is not even suggested. Furthermore, there is no description about achieving both high image quality and improved light fastness by using two or more inks having the same color tone and different image densities.
[0020]
(First and second modes)
One of the features according to the first aspect of the present invention is that when two types of inks having different color material densities are used for forming a color image, the first and second colors having the same color tone are used as the two types of inks. Each of these inks contains at least a common color material, and the second ink has a lower color material concentration than the first ink, and the second ink. The image obtained by the above method is the same as or less than the image obtained by the first ink.
[0021]
As described above, in the image formed by two types of inks having the same color tone and different densities, the present inventors proceeded more rapidly in the light color portion where the color material density is low, and both inks Even when the same color material is used as the light resistance, the image portion formed using light-colored ink becomes more discolored. As a result, the color balance of the entire image is lost and the image is visually deteriorated. I found that it gives an impression of progress. Therefore, in order to suppress such a phenomenon, in the present invention, when an ink set having the first and second water-based inks having the same color tone and including at least the common color material is configured, the second color material density is low. Compared with an image obtained with the first ink having a high colorant density, an image obtained with the same ink is used with the same or less light fading.
[0022]
One of the features according to the second aspect of the present invention is that when two types of inks having different color material concentrations are used for forming a color image, the first and second colors having the same color tone are used as the two types of inks. Two water-based inks, each of which includes at least a common color material, and the second ink has a lower color material concentration than the first ink, and the second ink The image obtained by is left under the prescribed conditionsAfterThe residual ratio of the reflection density of the second ink image was left under the same conditions as described above for the image obtained with the first ink.AfterIt is in the point which is more than the residual ratio of the reflection density of the first ink image. Here, it is preferable that the reflection density residual ratio of each image obtained by the first and second inks is 80% or more. The predetermined condition is, for example, 6,000 klux · hr. Degree of irradiation. That is, when left under such conditions, the ink image is faded, the reflection density is lowered, and visual image deterioration occurs. Therefore, in the present invention, when an ink set having the first and second water-based inks having the same color tone and including at least a common color material is configured, the above-described certain conditions are likely to cause image degradation. The decrease in the residual ratio of the reflection density with respect to the image obtained by the second ink having a relatively low color material density, which occurs when left untreated, is reduced with respect to the image obtained by the first ink having a relatively high color material density. The first ink having a high color material density and the second ink having a low color material density are used in combination so that the remaining ratio of the reflection density is not reduced or more.
[0023]
One method for bringing the first and second inks into such a relationship includes a method using an ink set in which inks appropriately selected as color materials in the first and second inks are combined. For example, when the first ink includes an ink set containing at least two kinds of color materials, or the ink set has a cyan color tone, for example, a common color material for the first and second inks. As C.I. I. Direct Blue 199 was used, and the first ink was further treated with C.I. I. Combinations using Acid Blue 9 and C.I. I. Acid Blue 307 is used, and C.I. I. Combinations using Acid Blue 9 are included.
When the ink set has a yellow color tone, for example, C.I. as a common color material for the first and second inks. I. Using direct yellow 86, C.I. I. Combinations using Acid Yellow 23 and C.I. I. Using direct yellow 132, C.I. I. A combination using Acid Yellow 23 is exemplified.
[0024]
Next, the case where the ink set has a magenta color tone will be described below.
(Coloring material)
The color material that can be used in the ink set of the present invention is not particularly limited, but is described in the color index, for example, water-soluble xanthene, triphenylmethane, anthraquinone, monoazo Disazo, trisazo, tetraazo, and copper phthalocyanine dyes are preferably used.
[0025]
Examples of suitable color materials that are commonly used for the first and second inks of magenta color include anthrapyridone dyes represented by the following general formula (I).

In the general formula (I), R₁Represents a substituted or unsubstituted alkoxy group or a substituted or unsubstituted aryl group;₂And R_FourEach independently represents a hydrogen atom or a substituted or unsubstituted alkyl group;_ThreeRepresents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, or a halogen atom. X₁Represents a carboxyl group or a salt thereof, or a sulfonic acid group or a salt thereof. n represents 1 or 2.
[0026]
R in the above general formula (I)₁~ R_FourMore specifically, R₁Examples thereof include a linear or branched alkoxy group having 1 to 4 carbon atoms and a substituted or unsubstituted phenyl group. Here, examples of the substituent of the phenyl group include a methyl group, a hydroxyl group, a nitro group, a sulfonic acid group or a salt thereof, a carboxyl group or a salt thereof, or a halogen atom (fluorine, chlorine, bromine, etc.). R₂Examples thereof include a hydrogen atom, a linear or branched lower alkyl group having 1 to 4 carbon atoms, and R_ThreeAs, for example, as a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, and an aryloxy group, for example, A phenoxy group etc. are mentioned. The aryl group constituting the aryloxy group may be substituted with, for example, a linear or branched alkyl group having 1 to 10 carbon atoms, a sulfonic acid group or a salt thereof, a carboxyl group or a salt thereof. In addition, R_FourExamples include a hydrogen atom and a linear or branched lower alkyl group having 1 to 4 carbon atoms. X₁X₁As, for example, -COOM or -SO_ThreeM [wherein M is a hydrogen atom, an alkali metal (eg, Li, Na, etc.), ammonium (NH_Four), Organic ammonium (N (R₈)_Four)] And the like. Where R₈Examples thereof include a methyl group or an ethyl group.
[0027]
Further, as a dye added in addition to the first ink that can be used together with the above-described color material, a xanthene dye, for example, C.I. I. Acid Red 52 and C.I. I. And at least one dye selected from Acid Red 289 and the like, at least one dye selected from the following general formulas (II) and (III), or both. In particular, as the coloring material in the first ink, the dye represented by the above general formula (I), the dye represented by the following general formula (II), and C.I. I. When combined with Acid Red 289, the magenta color tone of the image by the ink is particularly excellent, and this is particularly preferable for the formation of a photographic color image, together with the effect of suppressing the change in color balance. is there.
[0028]

In the general formula (II), Ar₁Represents a substituted or unsubstituted phenyl group, or a substituted or unsubstituted naphthyl group, Ar₂Acetyl group, benzoyl group, 1,3,5-triazinyl group, SO₂-C₆H_FiveGroup or SO₂-C₆H_Four-CH_ThreeRepresents any of the groups. M is a counter ion of a sulfonic acid group, and is a hydrogen atom, an alkali metal (for example, Li, Na, etc.), ammonium (NH_Four) And organic ammonium (N (R₉)_Four) Where R₉Examples thereof include a methyl group or an ethyl group.
[0029]
Ar₁Examples of the phenyl group and naphthyl group include a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a linear or branched alkyl group having 1 to 4 carbon atoms, a halogen atom (fluorine, chlorine, bromine, etc.) In addition, it may be substituted with one or two or more groups or atoms selected from an alkoxy group having 1 to 4 carbon atoms, an aryloxy group such as a phenoxy group, and the like. Ar₂Is a benzoyl group or a 1,3,5-triazinyl group, at least one hydrogen atom in the benzene ring or 1,3,5-triazine ring is a carboxyl group or a salt thereof, a halogen atom (fluorine, Chlorine, bromine and the like), a primary to tertiary amino group, an alkoxy group, a hydroxyl group and the like.
[0030]

In the general formula (III), Ar_ThreeAnd Ar_FourEach independently represents a substituted or unsubstituted phenyl group, or a substituted or unsubstituted naphthyl group. Examples of the substituent of the phenyl group or naphthyl group include, for example, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxyl group having 1 to 4 carbon atoms, a hydroxyl group, A carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a halogen atom (fluorine, chlorine, bromine, etc.), and the like. Ar_ThreeAnd Ar_FourAt least one of them has a carboxyl group or a salt thereof, or a substituent of a sulfonic acid group or a salt thereof. M is a counter ion of a sulfonic acid group, and is a hydrogen atom, an alkali metal (for example, Li, Na, etc.), ammonium (NH_Four) And organic ammonium (N (R_Ten)_Four) Where R_TenExamples thereof include a methyl group or an ethyl group. R_FiveRepresents a 1,3,5-triazinediyl group, and at least one hydrogen atom in the 1,3,5-triazine ring is a carboxyl group or a salt thereof, a halogen atom (fluorine, chlorine, bromine, etc.), 1 to It may be substituted with a tertiary amino group, an alkoxy group, a hydroxyl group or the like.
R₆And R₇Independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group-substituted or unsubstituted aralkyl group, or an atomic group necessary for forming a perhydroxyazine ring with N, and L is Represents a divalent organic linking group. R₆And R₇More specifically, for example, a linear or branched alkyl group having 1 to 6 carbon atoms, a linear or branched alkenyl group having 1 to 4 carbon atoms, a benzyl group, or the like can be given. . Here, examples of the substituent for the alkyl group, alkenyl group and benzyl group include a hydroxyl group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, and the like.
[0031]
Hereinafter, as specific examples of the first colorant represented by the above general formula (I) which is preferably used in the present invention, exemplary compounds I-1 to I-1IAlthough -7 is shown, the present invention is not limited to these color materials. Two or more of these color materials may be used simultaneously. Hereinafter, M in the exemplary compounds I-1 to I-7 is H, Li, Na, NH._FourAnd N (R₈)_FourRepresents one of the following.
[0032]

[0033]

[0034]

[0035]
Examples of the compound represented by the general formula (II) that is a color material suitably used in the present invention include C.I. I. Examples include Reactive Red 180, Exemplified Compounds II-8 to II-13 having the following structures, and compounds having structures described in JP-A-8-73791, JP-A-11-209673, and the like. It is done. Hereinafter, M in the exemplary compounds II-8 to II-13 is H, Li, Na, NH._FourAnd N (R₉)_FourRepresents one of the following.
[0036]

[0037]

[0038]

[0039]
In the present invention, examples of the compound of the general formula (III) used as a suitable coloring material include Exemplified Compounds III-14 to III-22 having the following structures. Hereinafter, M in the exemplified compounds III-14 to III-22 is H, Li, Na, NH._FourAnd N (R_Ten)_FourRepresents one of the following.
[0040]

[0041]

[0042]

[0043]

[0044]

[0045]
The mass ratio of the color material represented by the general formula (I) and the color material other than the general formula (I) in the first magenta ink is a clear color tone, high image density, and further excellent light resistance. Is considered to be in the range of 95: 5 to 20:80.
By the way, in each ink used in the present invention, regardless of the color tone of the ink, the content of all the color materials in each ink is the same as that of the dark ink of the first ink having a high color material density. On the other hand, in the light-color ink of the second ink having a low colorant density of 1.0 to 15.0% by mass, the one in the range of 0.1 to 5.0% by mass with respect to the total amount of ink should be used. preferable.
[0046]
(Aqueous medium)
Each ink used in the present invention is a water-based ink having a colorant and an aqueous medium as described above. The aqueous medium used in this case is not particularly limited as long as the water-soluble organic solvent contained in water or a mixed medium of water and a water-soluble organic solvent is water-soluble. , Polyglycol, glycol ether, nitrogen-containing polar solvent, sulfur-containing polar solvent and the like. These water-soluble organic solvents have a water-soluble organic solvent content of 1 to 40 of the whole ink in consideration of maintaining the moisture retention of the ink, improving the solubility of the coloring material, and effectively penetrating the ink into the recording paper. It is preferable to set it as the range of mass%, More preferably, it is set as the range of 3-30 mass%. In addition, the content of water in the ink is good because the colorant dye has good solubility in ink, has a viscosity for stable ink ejection, and does not cause clogging at the nozzle tip. Is preferably in the range of 30 to 95% by mass.
[0047]
(PH)
The pH of each ink used in the present invention is not particularly limited as long as it satisfies the solubility of the coloring material. However, in view of safety and the like, a pH in the range of 4.0 to 11.0 is preferable.
[0048]
(Additive)
When preparing each ink used in the present invention, a moisturizing solid content such as urea, a urea derivative, trimethylolpropane, etc. may be used as an ink component in order to maintain the moisturizing property of the ink. In general, the content of moisturizing solids such as urea, urea derivatives, trimethylolpropane, etc. in the ink is preferably in the range of 0.1 to 20.0% by mass, more preferably 3.0 to The range is 10.0% by mass. Furthermore, in addition to the above-mentioned components, each ink used in the present invention includes a surfactant, a pH adjuster, a rust inhibitor, an antiseptic, an antifungal agent, an antioxidant, an anti-reduction agent, and an evaporation as necessary. Various additives such as an accelerator, a chelating agent, and a water-soluble polymer may be contained.
The ink according to each embodiment of the ink set of the present invention described above is particularly preferably used for an ink jet recording method in which recording is performed by ejecting liquid droplets by the action of thermal energy. Needless to say, it can also be used as a writing instrument.
[0049]
(Recording device, ink cartridge, recording unit)
By the way, as a recording apparatus suitable for recording using the ink set of the present invention, thermal energy corresponding to the recording signal is given to the ink in the recording head chamber, and droplets are ejected from the orifice by the energy. An ink jet recording apparatus of the invention can be mentioned.
[0050]
Examples of the configuration of the recording head, which is the main part, are shown in FIGS. 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 the line AB of FIG. The head 13 is a heat generating head 15 having a glass, ceramic, or plastic plate having a groove 14 through which ink passes and a heat generating resistor used for thermal recording (the head is shown in the figure, but is not limited thereto). It is obtained by adhering The heat generating head 15 has good heat dissipation such as a protective film 16 formed of silicon oxide or the like, aluminum electrodes 17-1 and 17-2, a heat generating resistor layer 18 formed of nichrome or the like, a livestock heat layer 19, and alumina. It consists of a substrate 20. The ink 21 is filled up to the discharge orifice (fine hole) 22, and a meniscus 23 is formed by the pressure P.
[0051]
Here, when an electric signal is applied to the electrodes 17-1 and 17-2, the region indicated by the heat generating head 15n suddenly generates heat, and bubbles are generated in the ink 21 in contact therewith. The meniscus is ejected by the pressure, and becomes a recording droplet 24 from the orifice 22 to be recorded.(recoding media)Fly towards 25. FIG. 3 is a schematic view of a recording head having a multi-groove 26 in which a number of nozzles shown in FIG. 1 are arranged. The recording head is made by closely contacting a glass plate 27 having a large number of flow paths and a heating head 28 similar to the head described in FIG.
[0052]
FIG. 4 shows an example of an ink jet recording apparatus incorporating this head. In FIG. 4, 61 is a blade as a wiping member, one end of which is held by a blade holding member to become a fixed end and form a cantilever. The blade 61 is disposed at a position adjacent to the recording area by the recording head, and in the case of the example shown in FIG. 4, it is held in a form protruding in the moving path of the recording head. Reference numeral 62 denotes a cap, which is disposed at a home position adjacent to the blade 61 and moves in a direction perpendicular to the moving direction of the recording head so as to come into contact with the ejection surface and perform capping. Further, reference numeral 63 in FIG. 4 denotes 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.
The blade 61, the cap 62, and the absorber 63 constitute a discharge recovery portion 64, and the blade 61 and the absorber 63 remove moisture, dust, dust, and the like from the ink discharge port surface.
[0053]
Reference numeral 65 denotes 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 ports are arranged. It is a carriage for performing the movement. The carriage 66 is slidably engaged with the guide shaft 67, and a part of the carriage 66 is connected to a belt 69 driven by a motor 68 (not shown). Accordingly, 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.
Reference numeral 51 denotes a paper feed unit for inserting a recording material, and 52 denotes a paper feed roller driven by a motor (not shown). With these configurations, a recording material is fed to a position facing the ejection port surface of the recording head, and is discharged to a paper discharge unit provided with a paper discharge roller 53 as recording progresses.
[0054]
In the above configuration, when the recording head 65 returns to the home position due to the end of recording or the like, the cap 62 of the head 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 surface of the recording head 65 is wiped. 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 at the same position as that at the time of wiping described above. As a result, even in this movement, the ejection port surface of the recording head 65 is wiped.
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. In accordance with this movement, the wiping is performed.
[0055]
FIG. 5 is a cross-sectional view showing an example of an ink cartridge 45 that contains ink supplied to the head via an ink supply member, for example, a tube. Here, 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 thereof. By inserting a needle (not shown) into the stopper 42, the ink in the ink bag 40 can be supplied to the head. An ink absorber 44 receives waste ink. In the present invention, the ink storage portion of such an ink cartridge is filled with the first ink and the second ink constituting the ink set of the present invention, and each ink cartridge is caused to eject each ink. An excellent effect of the present invention is achieved by forming an image by mounting it on the head of an inkjet printer provided with an inkjet recording head for the purpose.
[0056]
As another example of the cartridge of the present invention filled with the first ink and the second ink constituting the ink set of the present invention, for example, the first ink as shown in FIG. Two storage portions 703 and 705 that individually store the second ink are provided, and as shown in FIG. 8, configured to be detachable from the inkjet head for individually discharging each ink. An example of the cartridge 701 is shown. Specifically, in FIG. 7, reference numeral 701 denotes a cartridge, reference numeral 703 denotes a first ink storage part that stores the first ink, and reference numeral 705 denotes a second ink storage part that stores the second ink. It is. Then, as shown in FIG. 8, the cartridge having the configuration shown in FIG. 7 can be attached to and detached from the recording head 801 that ejects two types of inks having different color material concentrations of the first ink and the second ink. In addition, when the cartridge 701 is mounted on the recording head 801, two types of inks having different color material densities are supplied to the recording head 801.
[0057]
The ink jet recording apparatus of the present invention is not limited to the recording head and the ink cartridge as described above, and an apparatus in which they are integrated as shown in FIG. 6 is also preferably used. In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink storage portion that stores each ink constituting the ink set of the present invention, for example, an ink absorber, is stored. Ink in the body is ejected as ink droplets from a head portion 71 having a plurality of orifices. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the recording unit 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.
[0058]
Furthermore, as another embodiment of the present invention, the first ink and the second ink constituting the ink set of the present invention are stored in each ink storage section in one ink tank, and A recording unit that is integrally provided with a recording head for discharging each ink. Specifically, for example, as shown in FIG. 9, the first ink is stored in the storage portion 901, and the second ink is stored. There is a recording unit 907 that includes a recording head 905 that is housed in the section 903 and further has a separate ink flow path so that each ink can be ejected individually.
In the above description, an example of an ink jet recording apparatus that ejects ink droplets by applying thermal energy to ink is used as the recording apparatus used in the present invention. In addition, a piezoelectric ink jet using a piezoelectric element is used. The recording apparatus can be used similarly.
[0059]
Next, other specific examples of the recording apparatus and the recording head that can be suitably used in the present invention will be described.
FIG. 10 shows a main part of an example of a liquid discharge head as a liquid discharge head of a discharge method that communicates bubbles with the atmosphere during discharge suitable for the present invention, and an ink jet printer as a liquid discharge apparatus using the liquid discharge head. It is a schematic perspective view shown. The ink jet printer shown in FIG. 10 has a transport device 1030 for intermittently transporting a sheet 1028 as a recording material provided along the longitudinal direction in a casing 1008 in the direction indicated by the arrow P shown in FIG. A recording unit 1010 that is reciprocated along a guide shaft 1014 substantially parallel to a direction S substantially orthogonal to the conveyance direction P of the paper 1028 by the conveying device 1030, and a driving unit for reciprocating the recording unit 1010 And a moving drive unit 1006.
[0060]
The conveying device 1030 includes a pair of roller units 1022a and 1022b that are arranged to face each other substantially in parallel, a pair of roller units 1024a and 1024b, and a drive unit 1020 for driving each of these roller units. Yes. With this configuration, when the driving unit 1020 of the transport device 1030 is activated, the paper 1028 is sandwiched between the roller units 1022a and 1022b and the roller units 1024a and 1024b, and the direction of the arrow P shown in FIG. Are conveyed intermittently.
Further, the movement drive unit 1006 is disposed substantially parallel to the belt 1016 wound around pulleys 1026a and 1026b disposed on the rotation shafts opposed to each other with a predetermined interval, and the roller units 1022a and 1022b, and the recording unit. And a motor 1018 for driving a belt 1016 coupled to a carriage member 1010a 1010 in the forward direction and the reverse direction.
[0061]
When the motor 1018 is activated and the belt 1016 rotates in the direction of arrow R in FIG. 10, 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. 10, the carriage member 1010a of the recording unit 1010 is predetermined in the direction opposite to the arrow S direction in FIG. Will be moved by the amount of movement. Further, a recovery unit 1026 for performing an ejection recovery process of the recording unit 1010 is opposed to the ink ejection port array of the recording unit 1010 at one end portion of the movement driving unit 1006 at a position serving as a home position of the carriage member 1010a. Is provided.
[0062]
In the recording unit 1010, inkjet cartridges (hereinafter simply referred to as cartridges) 1012Y, 1012M, 1012C, and 1012B are provided for each color, for example, for each of yellow, magenta, cyan, and black, a carriage member 1010a. Are detachably provided.
[0063]
FIG. 11 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 an ink jet recording head 100 and a liquid tank 1001 for containing a liquid such as ink. 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. 12). A cartridge 1012 shown in FIG. 11 has an inkjet recording head 100 and a liquid tank 1001 integrally formed so that liquid can be replenished into the liquid tank 1001 as necessary. A structure in which a liquid tank 1001 is connected to 100 in a replaceable manner may be adopted.
[0064]
Hereinafter, a specific example of the liquid discharge head that can be mounted on the ink jet printer having the above-described configuration will be described in more detail.
FIG. 12 is a schematic perspective view schematically showing the main part of the liquid discharge head showing the basic form of the present invention. FIGS. 13 to 16 show the discharge port shape of the liquid discharge head shown in FIG. FIG. Note that electrical wiring and the like for driving the electrothermal transducer are omitted.
[0065]
In the liquid discharge head of this example, for example, a substrate 934 made of glass, ceramics, plastic, metal or the like as shown in FIG. 12 is used. The material of such a substrate is not essential and 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. There is no particular limitation as long as it can function. In this example, a case where a Si substrate (wafer) is used will be described. In addition to the forming method using laser light, the discharge port can be formed by an exposure apparatus such as MPA (Mirror Projection Aliner) using, for example, an orifice plate (discharge port plate) 935 described later as a photosensitive resin.
[0066]
In FIG. 12, reference numeral 934 denotes a substrate including an electrothermal conversion element (hereinafter also referred to as a heater) 931 and an ink supply port 933 including a long groove-like through-hole as a common liquid chamber portion. On both sides in the longitudinal direction of the 933, heaters 931, which are thermal energy generating means, are arranged in a staggered manner, one row at a time, for example, with an interval between electrothermal conversion elements (heaters) of 300 dpi. On the substrate 934, an ink flow path wall 936 for forming an ink flow path is provided. The ink flow path wall 936 is further provided with a discharge port plate 935 having a discharge port 832.
[0067]
Here, in FIG. 12, the ink flow path wall 936 and the discharge port plate 935 are shown as separate members. However, the ink flow path wall 936 is placed on the substrate 934 by a technique such as spin coating. By forming the same, the ink flow path wall 936 and the discharge port plate 935 can be simultaneously formed as the same member. In this example, the discharge port surface (upper surface) 935a side is further subjected to water repellent treatment.
[0068]
In this example, a serial type head that performs recording while scanning in the direction of arrow S in FIG. 10 described above is used, and recording is performed at, for example, 1200 dpi. The drive frequency is 10 kHz, and one discharge port performs discharge at the shortest time interval of 100 μs. As an example of the actual dimensions of the head, for example, as shown in FIG. 13, a partition wall 936a that fluidly isolates adjacent nozzles has a width w = 14 μm. 1337 in the figure indicates a foaming chamber. Further, as shown in FIG. 16, the foaming chamber 1337 formed by the ink flow path wall 936 has N₁(Width dimension of foaming chamber) = 33 μm, 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 935 can be 11 μm in thickness.
[0069]
Of the cross section of the discharge port portion 940 provided in the discharge port plate 935 including the discharge port 832 shown in FIG. 12, a cross section cut in a direction crossing the ink discharge direction (thickness direction of the orifice plate 935). As shown in FIG. 14, the shape is substantially a star shape, and is alternately arranged between six raised portions 832a having obtuse angles and these raised portions 832a, and has acute angles. It is comprised roughly from the six protuberance part 832b which has. 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 raised 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 1141 are formed in the thickness direction (liquid ejection direction) of the orifice plate shown in FIG. 12 (see FIG. 14).
[0070]
In this example, the discharge port portion 940 has a shape in which, for example, a cross section cut in a direction intersecting the thickness direction is a combination of two regular triangles each having a side of 27 μm and rotated by 60 degrees. T shown in 14₁Is 8 μm. The angles of the raised parts 832a are all 120 degrees, and the angles of the protuberance parts 832b are all 60 degrees. 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 μm.²The opening area of the groove (the area of the figure formed by connecting the top of the groove and the two bases adjacent to the top) is about 33 μm per one.²It has become. FIG. 15 is a schematic diagram showing an ink adhering state at the discharge port portion shown in FIG. 14, where C is wet ink.
[0071]
Next, a liquid discharge operation by the ink jet recording head having the above-described configuration will be described with reference to FIGS. 17 to 24 are cross-sectional views for explaining the liquid discharge operation of the liquid discharge head described in FIGS. 12 to 16, and are cross-sectional views taken along line XX of the foaming chamber 1337 shown in FIG. In this cross section, the end of the discharge port 940 shown in FIG. 12 in the orifice plate thickness direction is the top 1141 a of the groove 1141. FIG. 17 shows a state in which film-like bubbles are generated on the heater, and FIGS. 18 to 24 show the subsequent bubble states over time. 18 is about 1 μs after FIG. 17, FIG. 19 is about 2 μs after FIG. 17, FIG. 20 is after about 3 μs after FIG. 17, FIG. 21 is after about 4 μs after FIG. FIG. 23 shows the state after about 5 μs in FIG. 17, FIG. 23 shows the state after about 6 μs in FIG. 17, and FIG. 24 shows the state after about 7 μs in FIG. In the following description, “falling” or “falling” and “falling” do not mean the so-called dropping in the direction of gravity, but the movement in the direction of the electrothermal conversion element regardless of the head mounting direction. It means that.
[0072]
First, as shown in FIG. 17, 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, in about 2 μs, FIG. As shown in FIG. 19, the bubble 101 rapidly expands and grows. The height of the bubble 101 at the maximum volume exceeds the discharge port surface 935a, but at this time, the pressure of the bubble is reduced from a fraction of atmospheric pressure to a fraction of ten.
[0073]
Next, at a time point after about 2 μs from the generation of the bubble 101, as described above, the bubble 101 changes from the maximum volume to the volume decrease, but at the same time, the formation of the meniscus 102 also starts. As shown in FIG. 20, the meniscus 102 also moves backward, that is, falls in the direction toward the heater 931. Here, in this example, as described above, since the plurality of grooves 1141 are dispersed in the discharge port portion, when the meniscus 102 retreats, the meniscus 102 is formed in the groove 1141 portion. Reverse direction F_MDirection F opposite_CCapillary force acts on. As a result, even if some variation in the state of the bubble 101 is recognized for some reason, the meniscus and the main liquid droplet (hereinafter sometimes referred to as liquid or ink) I when the meniscus 102 is retracted I_aIs corrected so as to be substantially symmetrical with respect to the center of the discharge port.
[0074]
In this example, since the falling speed of the meniscus 102 is faster than the contraction speed of the bubbles 101, the bubbles 101 are near the lower surface of the discharge port 832 at a time point about 4 μs after the generation of the bubbles, as shown in FIG. To communicate with the atmosphere. At this time, the liquid (ink) in the vicinity of the central axis of the ejection port 832 falls toward the heater 931. This is because the liquid (ink) I drawn back to the heater 931 side by the negative pressure of the bubbles 101 before communicating with the atmosphere._aHowever, even after the bubble 101 communicates with the atmosphere, the speed in the surface direction of the heater 931 is maintained by inertia. The liquid (ink) that has fallen toward the heater 931 side reaches the surface of the heater 931 at about 5 μs after the generation of the bubble 101 as shown in FIG. 22, and as shown in FIG. It spreads so as to cover the surface.
[0075]
The liquid spreading so as to cover the surface of the heater 931 in this way has a horizontal vector along the surface of the heater 931, but crosses the surface of the heater 931, for example, the vertical vector disappears, and the heater It tries to stay on the surface of 931 and pulls the liquid above it, that is, the liquid that maintains the velocity vector in the ejection direction, downward. Thereafter, the liquid I between the liquid spread on the surface of the heater 931 and the upper liquid (main droplet)._bAs shown in FIG. 24, the liquid I reaches the center of the surface of the heater 931 at about 7 μs after the generation of the bubbles 101, as shown in FIG._bAnd the main droplet I which keeps the velocity vector in the discharge direction is cut_aAnd the liquid I spreading on the surface of the heater 931_cAnd separated. Thus, the separation position is preferably inside the liquid flow path 1338, more preferably on the electrothermal conversion element (heater) 931 side with respect to the discharge port 832.
[0076]
Main droplet I_aIs discharged from the central portion of the discharge port 832 without any deviation in the discharge direction and landing on a predetermined position on the recording surface of the recording material. Further, the liquid I spread on the surface of the heater 931._cIn the prior art, the droplets fly as satellite droplets following the main droplets, but stay on the surface of the heater 931 and are not discharged. In this way, since it is possible to suppress the discharge of satellite droplets, it is possible to prevent the splash that is likely to occur due to the discharge of satellite droplets, and to prevent the recording surface of the recording material from being contaminated by the mist floating in the form of mist. It can be surely prevented. In FIGS. 18 to 24, I represents ink, I_dIndicates ink adhering to the groove (ink in the groove), and I_eRepresents ink remaining in the liquid flow path.
[0077]
As described above, in the liquid discharge head of this example, when liquid is discharged in the volume reduction stage after the bubble has grown to the maximum volume, the discharge is performed by the plurality of grooves dispersed with respect to the center of the discharge port. The direction of the main droplet at the time can be stabilized. As a result, it is possible to provide a liquid ejection head with no landing deviation and high landing accuracy. In addition, high-speed and high-definition printing can be realized by being able to stably discharge even foaming variation at a high driving frequency.
[0078]
In particular, at the stage of reducing the volume of the bubbles, by discharging the liquid by first communicating the bubbles with the atmosphere, it is possible to prevent mist generated when discharging the droplets by communicating the bubbles with the atmosphere. It is also possible to suppress a state in which droplets adhere to the discharge port surface, which causes sudden discharge failure. In addition, as another embodiment of a recording head of a discharge method that can be suitably used in the present invention and communicates air bubbles with the atmosphere at the time of discharge, for example, a so-called edge shooter type is disclosed in Japanese Patent Registration No. 2783647. Can be mentioned.
[0079]
【Example】
Next, the present invention will be described in more detail with reference to examples and comparative examples. Unless otherwise specified, the ink components in Examples and Comparative Examples mean “parts by mass”.
<Examples 1-7, Comparative Examples 1-6>
To each component shown in ink composition 1 below, add the colorant shown in Table 1 or 2 in the amount shown in the table, and further add ion exchange water to make the total amount 100 parts, and then mix Then, pressure filtration was performed with a 0.20 μm filter, and ink sets of Examples 1 to 7 and Comparative Examples 1 to 6 made of two kinds of inks having different color material concentrations were produced.
[0080]
(Ink composition 1)
・ Glycerin 5.0 parts
・ 5.0 parts of urea
・ Diethylene glycol 10.0 parts
・ 0.3 parts of acetylenol EH (manufactured by Kawaken Fine Chemical Co., Ltd.)
・ 5.0 parts of ethanol
[0081]

[0082]

[0083]
<Evaluation>
For each of the ink sets of Examples 1 to 7 and Comparative Examples 1 to 6 obtained above, images were formed using the first and second inks constituting the ink set, and the following method was used. The light resistance of the first and second inks and the color developability of the first ink were evaluated. At that time, an image was formed using an ink jet recording apparatus, but printing was performed using an on-demand ink jet printer using a heating element as an energy source for ink ejection.
[0084]
[Light resistance]
Ink of each of the above-described embodiments or comparative examples, in which an inkjet printer is configured by combining a dark ink (first ink) with a high color material density and a light ink (second ink) with a low color material density. The set was set to obtain a printed matter in which a solid portion was printed on two types of recording materials, PPC paper (manufactured by Canon) and glossy paper (PR-101; manufactured by Canon). Each printed matter obtained was air-dried for 24 hours, and a xenon fade meter Ci3000 (manufactured by Atlas Co., Ltd.) equipped with an ultraviolet cut filter was used. And irradiated for 100 hours. Then, the reflection density of each ink image of the printed matter before and after the test was measured with a reflection densitometer Macbeth RD-918 (trade name: manufactured by Macbeth Co.), and the residual density rate after the test was obtained. The density residual ratio in the dark ink (first ink) at that time was evaluated according to the following criteria, and is shown in [1-a] in Table 3. Furthermore, using the obtained density residual ratio, the density residual ratio between the first and second inks constituting each ink set was compared, and evaluated using the following criteria. [1-b in Table 3] ]Pointing out toungue.
[0085]
[1-a] Density residual ratio of dark ink (first ink)
A: Dark ink density remaining rate is 80% or more
B: The density remaining rate of dark ink is 60% or more and less than 80%
C: The density remaining rate of dark ink is less than 60%
[0086]
[1-b] Comparison of light resistance between dark (first) ink and light (second) ink
A: The density residual ratio of the light color ink is equal to or higher than the density residual ratio of the dark color ink.
B: The density residual ratio of light color ink is less than the density residual ratio of dark color ink
[0087]
[Color development]
Images are formed using the dark ink (first ink) of the inks constituting the ink sets of Examples 1 to 7 and Comparative Examples 1 to 6 obtained above, and the following method is used. The color development was examined. In the ink jet printer, dark ink (first ink) having a high color material density of each ink set is set, and PPC paper (made by Canon) and glossy paper (PR-101; made by Canon) are used. Two types of recording materials were used, and solid portions were printed on each of them. The obtained printed matter was naturally dried for 24 hours, its color development property was visually observed, evaluated according to the following criteria, and the results are shown in Table 3.
AA: Particularly bright colors.
A: One having a vivid color tone.
B: Slightly dull color tone.
[0088]

[0089]
Furthermore, for the printed matter formed with the ink sets of the above-mentioned Examples and Comparative Examples, the printed matter before and after the light irradiation used for evaluating the light resistance was visually compared, and each printed matter was amber. The state was observed. As a result, any printed matter formed using the ink sets of Examples 1 to 7 and the printed portion of the first ink having a relatively high color material density and the color material density relatively low. In the printed part of the second ink, no noticeable fading was observed. On the other hand, the printed matter formed using the ink sets of Comparative Examples 1 to 6 showed a partial change in color tone due to the fading of the printed portion by the second ink after irradiation with light. It was found that the printed matter after the test gave an impression that the fading was remarkable. It has been found that an image formed using the first and second inks constituting the ink set of the present invention can suppress a change in color balance over time due to a difference in light fastness degradation rate.
[0090]
【The invention's effect】
As described above, according to the present invention, there are provided an ink set, an ink jet recording apparatus, and an ink jet recording method capable of providing excellent light resistance and a clear image when printed on various recording papers. The present invention also provides an ink set, an ink jet recording apparatus, and an ink jet recording method capable of providing an ink jet color image in which color balance is not easily lost even when the formed image is stored for a long period of time.
Further, according to the present invention, an ink jet recording method capable of forming an ink jet color image that is more durable with an image and that is difficult to visually perceive deterioration even when the image is stored for a long period of time, and to be used therefor An ink jet recording apparatus, a recording unit, and an ink cartridge are provided.
Furthermore, according to the present invention, even when an image is stored for a long period of time, a magenta ink set, an ink jet recording apparatus, and the like that can suppress a change in visual color balance caused by deterioration of a magenta color image, in particular. An ink jet recording method is provided. Furthermore, according to the present invention, there is provided a recording unit and an ink cartridge that can be extremely effectively used for forming an excellent inkjet color image in which image deterioration due to magenta color image deterioration or the like is difficult to recognize.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a head portion of an ink jet recording apparatus.
FIG. 2 is a cross-sectional view of a head portion of the ink jet recording apparatus.
FIG. 3 is an external perspective view of a head portion of the ink jet recording apparatus.
FIG. 4 is a perspective view illustrating an example of an ink jet recording apparatus.
FIG. 5 is a longitudinal sectional view of an ink cartridge.
FIG. 6 is a perspective view of a recording unit.
FIG. 7 is a schematic view showing an embodiment of the ink cartridge of the present invention.
8 is a schematic view of a recording head equipped with the ink cartridge of FIG.
FIG. 9 is a schematic view showing an embodiment of a recording unit of the present invention.
FIG. 10 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. 11 is a schematic perspective view illustrating an example of an ink jet cartridge provided with a liquid discharge head.
FIG. 12 is a schematic perspective view schematically illustrating a main part of an example of a liquid discharge head.
FIG. 13 is a conceptual diagram in which a part of an example of a liquid discharge head is extracted.
14 is an enlarged view of a portion of the discharge port shown in FIG.
15 is a schematic diagram illustrating an ink adhesion state at a discharge port portion illustrated in FIG. 14;
16 is a schematic diagram of a main part in FIG. 13;
17 is a schematic cross-sectional view corresponding to the cross-sectional shape taken along the line XX in FIG. 16 and illustrating the liquid discharge operation of the liquid discharge head over time together with FIGS. 18 to 24. FIG.
18 is a schematic cross-sectional view for explaining the liquid discharge operation of the liquid discharge head over time corresponding to FIG. 16 and FIG. 19 to FIG. 24, corresponding to the cross-sectional shape taken along the line XX in FIG.
FIG. 19 is a schematic cross-sectional view for explaining the liquid discharge operation of the liquid discharge head over time, corresponding to the cross-sectional shape taken along the line XX in FIG. is there.
20 is a schematic cross-sectional view for explaining the liquid discharge operation of the liquid discharge head over time together with FIGS. 17 to 19 and FIGS. 21 to 24, corresponding to the cross-sectional shape taken along the line XX in FIG. is there.
21 is a schematic cross-sectional view for explaining the liquid discharge operation of the liquid discharge head over time together with FIGS. 17 to 20 and FIGS. 22 to 24, corresponding to the cross-sectional shape taken along the line XX in FIG. is there.
22 is a schematic cross-sectional view for explaining the liquid discharge operation of the liquid discharge head over time, together with FIGS. 17 to 21, 23, and 24, corresponding to the cross-sectional shape taken along the line XX in FIG. is there.
23 is a schematic cross-sectional view corresponding to the cross-sectional shape taken along the line XX in FIG. 16 and illustrating the liquid discharge operation of the liquid discharge head over time together with FIGS. 17 to 22 and 24. FIG.
24 is a schematic cross-sectional view corresponding to the cross-sectional shape taken along the line XX in FIG. 16 and illustrating the liquid discharge operation of the liquid discharge head over time together with FIGS. 17 to 23. FIG.
[Explanation of symbols]
13: Head
14: Groove
15: Heat generating head
16: Protective film
17-1, 17-2: Aluminum electrode
18: Heating resistor layer
19: Thermal storage layer
20: Substrate
21: Ink
22: Discharge orifice
23: Meniscus
24: Recording droplet
25: Recording material
26: Multi groove
27: Glass plate, etc.
28: Heat generating head
40: Ink bag
42: stopper
44: Ink absorber
45: Ink cartridge
51: Paper feed unit
52: Paper feed roller
53: Paper discharge roller
61: Wiping member (blade)
62: Cap
63: Ink absorber
64: Discharge recovery part
65: Recording head
66: Carriage
67: Guide shaft
68: Motor
69: Belt
70: Recording unit
71: Head part
72: Air communication port
100: Inkjet recording head
101: Bubble
102: Meniscus
701: Cartridge
703: First ink container
705: Second ink container
801: Recording head
832: Discharge port
832a: Starting part
832b: Prone
901: First ink container
903: Second ink container
905: Recording head
907: Recording unit
931: Electrothermal conversion element (heater, ink discharge energy generating element)
933: Ink supply port (opening)
934: Substrate
935: Orifice plate (discharge port plate)
935a: discharge port surface
936: Ink channel wall
936a: partition wall
940: Discharge port
1001: Liquid tank
1006: Movement drive unit
1008: Casing
1010: Recording unit
1010a: Carriage member
1012: Cartridge
1012Y, M, C, B: Inkjet cartridge
1014: Guide shaft
1016: Belt
1018: Motor
1020: Drive unit
1022a, 1022b: Roller unit
1024a, 1024b: Roller unit
1026: Recovery unit
1026a, 1026b: pulley
1028: Paper
1030: Conveying device
1141: Groove
1141a: top
1337: Foaming chamber
1338: Liquid flow path
C: Wet ink
F_M: Meniscus backward direction
F_C: Direction opposite to meniscus retreat direction
G: Center of gravity
I: Ink
I_a: Main droplet (liquid, ink)
I_b, I_c: Liquid (ink)
I_d: Ink adhering to the groove (ink in the groove)
I_e: Ink remaining in the liquid flow path
N₁: Width of foaming chamber
N₂: Length of foaming chamber
O: Center of discharge port
P: Paper transport direction
R: Belt rotation direction
S: direction substantially orthogonal to the paper transport direction
w: Width of bulkhead

Claims (20)

An ink set having first and second aqueous inks of the same color, wherein each of the first and second inks includes at least a common dye as a color material, and the second ink is a first ink. An image obtained by the first ink having a lower density of the color material and the residual ratio of the reflection density of the second ink image after leaving the image obtained by the second ink under predetermined conditions. Or more than the residual ratio of the reflection density of the first ink image after being left under the same conditions as above,
In order to satisfy the relationship between the residual ratios of the reflection densities of the first ink image and the second ink image, each of the first and second inks contains at least a common dye as a coloring material, and the first ink further includes An ink set comprising other dye as a coloring material . The ink set according to claim 1 , wherein the predetermined condition is exposure to light from a xenon lamp. The ink set according to claim 1 or 2 , wherein both the first ink and the second ink have a cyan color tone. The ink set according to claim 1 or 2 , wherein both the first ink and the second ink have a yellow color tone. The ink set according to claim 1 or 2 , wherein both the first ink and the second ink have a magenta color tone. The ink set according to claim 5 , wherein the second ink contains a dye represented by the following general formula (I) as the only coloring material.

(In the above general formula (I), R ₁ represents a substituted or unsubstituted alkoxy group or a substituted or unsubstituted aryl group, and R ₂ and R ₄ each independently represents a hydrogen atom or a substituted or unsubstituted group. R ₃ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, or a halogen atom, and X ₁ represents a carboxyl group or The salt represents a sulfonic acid group or a salt thereof, and n represents 1 or 2.) The first ink is, as a color material, at least one dye selected from a dye represented by the following general formula (II) and a dye represented by the following general formula (III), and a dye represented by the following general formula (I) the ink set according to claim 5 or 6 contains and.

(In the above general formula (I), R ₁ represents a substituted or unsubstituted alkoxy group or a substituted or unsubstituted aryl group, and R ₂ and R ₄ each independently represents a hydrogen atom or a substituted or unsubstituted group. R ₃ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, or a halogen atom, and X ₁ represents a carboxyl group or The salt represents a sulfonic acid group or a salt thereof, and n represents 1 or 2.)

(In the general formula (II), Ar ₁ represents a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group, Ar ₂ represents an acetyl group, a benzoyl group, a 1,3,5-triazinyl group, Represents either an SO ₂ —C ₆ H ₅ group or an SO ₂ —C ₆ H ₄ —CH ₃ group, where M is a counter ion of the sulfonic acid group, and is any of a hydrogen atom, an alkali metal, ammonium, and organic ammonium. Represents.)

(In the general formula (III), Ar ₃ and Ar ₄ are each independently a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group, and at least one of Ar ₃ and Ar ₄ is a carboxyl group. Group or a salt thereof, or a substituent of a sulfonic acid group or a salt thereof, M is a counter ion of the sulfonic acid group, and represents any one of a hydrogen atom, an alkali metal, ammonium, and organic ammonium, R ₅ R ₆ and R ₇ independently represent a hydrogen atom, an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an aralkyl group, a substituted aralkyl group or N (This represents an atomic group necessary for forming a hydroxyazine ring, and L represents a divalent organic linking group.) The first ink further contains C.I. I. Acid Red 52 and C.I. I. The ink set according to claim 7 , comprising at least one of Acid Red 289. The first ink contains C.I. I. Acid Red 52 and C.I. I. The ink set according to claim 5 or 6 , comprising at least one of Acid Red 289 and a dye represented by the following general formula (I).

(In the above general formula (I), R ₁ represents a substituted or unsubstituted alkoxy group or a substituted or unsubstituted aryl group, and R ₂ and R ₄ each independently represents a hydrogen atom or a substituted or unsubstituted group. R ₃ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, or a halogen atom, and X ₁ represents a carboxyl group or The salt represents a sulfonic acid group or a salt thereof, and n represents 1 or 2.) The ink set according to any one of claims 1 to 9 , wherein the content of all the color materials in the first ink is in the range of 1.0 to 15.0 mass% with respect to the ink. The ink set according to any one of claims 1 to 10 , wherein the content of all the color materials in the second ink is in a range of 0.1 to 5.0 mass% with respect to the ink. Each image obtained by the first ink and the second ink contains 6,000 klux · hr. The ink set according to any one of claims 1 to 11, wherein a residual ratio of reflection density of each image after irradiation with the light of 80% or more is 80% or more. Wherein the first ink and the ink set according to any one of claims 1 to 1 2 second ink is an ink for use in ink jet recording. An ink jet recording apparatus comprising an ink containing portion containing first and second water-based inks having the same color tone and a head portion for discharging the ink, wherein the first and second inks Each includes at least a common dye as a color material, the second ink has a lower color material concentration than the first ink, and an image obtained by the second ink is left under predetermined conditions. The residual ratio of the reflection density of the subsequent second ink image is equal to or greater than the residual ratio of the reflection density of the first ink image after the image obtained by the first ink is left under the same conditions as described above.
In order to satisfy the relationship between the residual ratios of the reflection densities of the first ink image and the second ink image, each of the first and second inks contains at least a common dye as a coloring material, and the first ink further includes An ink jet recording apparatus comprising another dye as a color material . Each image obtained by the first ink and the second ink contains 6,000 klux · hr. An ink jet recording apparatus according to claim 1 4 reflection density residual ratio of each of the image after irradiation with light is 80% or more of. An ink jet recording method comprising a step of applying a first aqueous ink and a second aqueous ink having the same color tone, at least a common dye as a color material, and having different color material concentrations to a recording medium. The second ink has a lower color material density than the first ink, and the reflection of the second ink image after leaving the image obtained by the second ink under predetermined conditions. The residual ratio of the density is equal to or higher than the residual ratio of the reflection density of the first ink image after leaving the image obtained by the first ink under the same conditions as described above;
In order to satisfy the relationship between the residual ratios of the reflection densities of the first ink image and the second ink image, each of the first and second inks contains at least a common dye as a coloring material, and the first ink further includes An ink jet recording method comprising another dye as a coloring material . Each image obtained by the first ink and the second ink contains 6,000 klux · hr. The inkjet recording method according to claim 16 , wherein the residual ratio of reflection density of each image after irradiation with the light is 80% or more. A second water-based ink used in an ink set having the first and second water-based inks having the same color tone, wherein a dye common to the dye as the color material contained in the first water-based ink is used as the color material. A second aqueous ink having a lower colorant density than the first ink, the remaining reflection density of the second ink image after leaving the image obtained by the second ink under predetermined conditions The rate is equal to or higher than the residual rate of the reflection density of the first ink image after leaving the image obtained by the first ink under the same conditions as described above,
In order to satisfy the relationship between the residual ratios of the reflection densities of the first ink image and the second ink image, each of the first and second inks contains at least a common dye as a coloring material, and the first ink further includes A second water-based ink comprising another dye as a coloring material . Each image obtained by the first ink and the second ink contains 6,000 klux · hr. The second water-based ink according to claim 18 , wherein the residual ratio of reflection density of each image after irradiation with the light of 80% is 80% or more. The second ink is a water-based ink containing a dye represented by the following general formula (I) as the only color material, and the first ink is represented by the following general formula (II) as the color material. The water-based ink according to claim 18 or 19 , comprising at least one dye selected from dyes represented by the following general formula (III) and at least one dye represented by the following general formula (I): Second aqueous ink.

(In the above general formula (I), R ₁ represents a substituted or unsubstituted alkoxy group or a substituted or unsubstituted aryl group, and R ₂ and R ₄ each independently represents a hydrogen atom or a substituted or unsubstituted group. R ₃ represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group, or a halogen atom, and X ₁ represents a carboxyl group or The salt represents a sulfonic acid group or a salt thereof, and n represents 1 or 2.)

(In the general formula (II), Ar ₁ represents a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group, Ar ₂ represents an acetyl group, a benzoyl group, a 1,3,5-triazinyl group, Represents either an SO ₂ —C ₆ H ₅ group or an SO ₂ —C ₆ H ₄ —CH ₃ group, where M is a counter ion of the sulfonic acid group, and is any of a hydrogen atom, an alkali metal, ammonium, and organic ammonium. Represents.)

(In the general formula (III), Ar ₃ and Ar ₄ are each independently a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group, and at least one of Ar ₃ and Ar ₄ is a carboxyl group. Group or a salt thereof, or a substituent of a sulfonic acid group or a salt thereof, M is a counter ion of the sulfonic acid group, and represents any one of a hydrogen atom, an alkali metal, ammonium, and organic ammonium, R ₅ R ₆ and R ₇ independently represent a hydrogen atom, an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an aralkyl group, a substituted aralkyl group or N (This represents an atomic group necessary for forming a hydroxyazine ring, and L represents a divalent organic linking group.)

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