JP3805006B2 - Ink, ink jet recording method, recording unit, ink cartridge and ink jet recording apparatus using the same - Google Patents

Description

Ａｒ¹及びＡｒ²は、各々独立に、アリール基又は置換アリール基であって、Ａｒ¹とＡｒ²の少なくとも１つが独立にＣＯＯＨとＣＯＳＨから選ばれる置換基を１個以上有する。Ｒ¹及びＲ²は独立に、Ｈ、アルキル基、置換アルキル基、アルケニル基又は置換アルケニル基を表し、Ｌは２価の有機連結基を表し、ｎは０又は１を表す。Ｘは夫々独立に、カルボニル基、又は下記（１）〜（３）式で示される基を表す。
【００２０】

（Ｚは夫々独立にＮＲ³Ｒ⁴、ＳＲ⁵又はＯＲ⁵を表し、ＹはＨ、Ｃｌ、Ｚ、ＳＲ⁶又はＯＲ⁶を表し、ＥはＣｌ又はＣＮを表す。Ｒ³、Ｒ⁴、Ｒ⁵及びＲ⁶は夫々独立にＨ、アルキル基、置換アルキル基、アルケニル基、置換アルケニル基、アリール基、置換アリール基、アラルキル基、置換アラルキル基を表し、Ｒ³又はＲ⁴は窒素原子と共に５又は６員環を形成することもある。）
又、一般式（Ｉ）で表される化合物は、少なくともＳＯ₃Ｈと同数のＣＯＯＨ又はＣＯＳＨから選ばれた基を有する。）
【００２１】
一般式（Ｉ）で示される色材として、具体的には、例えば、以下のようなものが挙げられる。

【００２２】

【００２３】
遊離酸の状態で下記一般式（II）で表わされる色材

（式中、Ａｒ及びＡｒ¹は夫々アリール基又は置換アリール基を示し、Ａｒ及びＡｒ¹の少なくとも１つはＣＯＯＨ又はＣＯＳＨから選ばれる置換基を有する。Ｊ及びＪ¹は夫々下記一般式（４）、（５）及び（６）からなる群から選ばれる構造からなる
【００２４】

（式中、Ｒ⁵は独立的に、Ｈ、アルキル基、置換アルキル基、アルコキシ基、ハロゲン、ＣＮ、ウレイド及びＮＨＣＯＲ⁶から選択される。Ｒ⁶はＨ、アルキル基、置換アルキル基、アリール基、置換アリール基、アラルキル基及び置換アラルキル基から選択される。Ｔはアルキル基を示し、ＷはＨ、ＣＮ、ＣＯＮＲ¹⁰Ｒ¹¹、ピリジウム及びＣＯＯＨから選択される。（ｍ）は炭素数２〜８のアルキレン鎖を示し、ＢはＨ、アルキル基及びＣＯＯＨから選択される。Ｒ¹⁰及びＲ¹¹は夫々Ｈ、アルキル基及び置換アルキル基から選択される。）。
【００２５】
Ｒ¹、Ｒ²、Ｒ³及びＲ⁴は夫々Ｈ、アルキル基及び置換アルキル基から選択され、Ｌは２価の有機結合基を示し、ｎは０又は１を示す。Ｘはカルボニル基又は下記一般式（７）、（８）又は（９）の構造からなる。
【００２６】

（式中、Ｚは、ＯＲ⁷、ＳＲ⁷及びＮＲ⁸Ｒ⁹から選択され、ＹはＨ、Ｃｌ、ＣＮ及びＺから選択され、ＥはＣｌ及びＣＮから選択される。Ｒ⁷、Ｒ⁸及びＲ⁹は夫々Ｈ、アルケニル基、置換アルケニル基、アルキル基、置換アルキル基、アリール基、置換アリール基、アラルキル基及び置換アラルキル基から選択される。更にＲ⁸及びＲ⁹はこれらが結合された窒素原子と共に５員環又は６員環を形成する場合もある。）
▲１▼一般式（II）がＳＯ₃Ｈ基をもたない場合は、少なくとも２つのＣＯＯＨ基又はＣＯＳＨ基から選ばれる基を有し、▲２▼一般式（II）がＳＯ₃Ｈ基をもつ場合は、ＣＯＯＨ基又はＣＯＳＨ基から選ばれる基が少なくともＳＯ₃Ｈ基の数と同数以上有する。）
【００２７】
一般式（II）で表わされる色材としては、具体的には、例えば、以下の様なものが挙げられる。

【００２８】

【００２９】

【００３０】

【００３１】

【００３２】
遊離酸の形で下記一般式（III）で表わされる色材：

（式中、Ｒ₁及びＲ₂は夫々独立に水素原子、カルボキシル基、スルホン基及び炭素数１〜２のアルキル基から選ばれ、Ｘ及びＹは夫々独立にＮＲ₃Ｒ₄及びＮＲ₅Ｒ₆から選ばれる。Ｒ₃及びＲ₄は夫々独立にアルキル基、置換アルキル基、アリール基、置換アリール基、アラルキル基、置換アラルキル基、アルコキシル基及び置換アルコキシル基から選ばれ、Ｒ₅は水素原子、アルキル基、置換アルキル基、アルケニル基、置換アルケニル基、アラルキル基、置換アラルキル基、アルコキシル基及び置換アルコキシル基から選ばれ、Ｒ₆はＣＯＳＨ又はＣＯＯＨで置換された無色有機残基を表わす。）
【００３３】
一般式（III）で表わされる化合物としては、具体的には、以下のものが挙げられる。

【００３４】
遊離酸の状態で下記一般式（IV）で表わされる色材

（上記一般式（IV）中、Ｒ₁、Ｒ₂及びＲ₂´は夫々、カルボキシル基、スルホン基、水酸基、アミノ基、炭素数１〜２のアルキル基及び水素原子から選ばれ、Ｒ₃、Ｒ₄、Ｒ₅及びＲ₆はカルボキシル基、スルホン基、アミノ基、水酸基、アルキルアミド基及び水素原子から選ばれる。
【００３５】
又、Ｘは下記一般式（Ａ）、又は（Ｂ）の構造からなる。

（上記一般式（Ａ）及び（Ｂ）中、Ｒ₇はカルボキシル基、スルホン基及び水素原子から選ばれる。Ｒ₈、Ｒ₉はカルボキシル基、スルホン基、下記式で表わされる構造及び水素からなる群から選ばれる。

（上記式中、ｎは１〜５の整数を、ｍは０又は１を夫々表す。）））
【００３６】
一般式（IV）で示される色材として、具体的には、例えば、以下の様なものが挙げられる。
【００３７】

【００３８】

【００３９】

【００４０】

【００４１】
尚、上記した例示化合物の中で、化学構造中に、ＳＯ ₃ Ｈ基をもたない場合は少なくとも２つのＣＯＯＨ基を有し、ＳＯ ₃ Ｈ基をもつ場合はＣＯＯＨ基をＳＯ ₃ Ｈ基の数と同数以上で且つ２以上を有する色材としては、染料１〜２３及び２６が該当する。又、本発明で使用される色材が、遊離酸の状態での色材の水溶性基種と、水溶性高分子化合物の有する水溶性基種とが同種のものであり、且つ上記の色材の水溶性基数が、色材中に有する他の水溶性基数と同数或いはそれ以上のものである場合に信頼性がより良好になる傾向がある。更に、記録物の耐水性等の向上を考慮に入れると、上記の場合の水溶性基が遊離酸の状態でカルボン酸である場合が特に良好である。
【００４２】
本発明で使用される液媒体は、水と水溶性有機溶剤との混合物であることが好ましい。具体的な水溶性有機溶剤の例としては、例えば、ジメチルホルムアミド、ジメチルアセトアミド等のアミド類；アセトン等のケトン類；テトラヒドロフラン、ジオキサン等のエーテル類；ポリエチレングリコール、ポリプロピレングリコール等のポリアルキレングリコール類；エチレングリコール、プロピレングリコール、ブチレングリコール、トリエチレングリコール、１，２，６−ヘキサントリオール、チオジグリコール、ヘキシレングリコール、ジエチレングリコール等のアルキレン基が２〜６個の炭素原子を含むアルキレングリコール類；グリセリン；エチレングリコールモノメチル（又はエチル）エーテル、ジエチレングリコールモノメチル（又はエチル）エーテル、トリエチレングリコールモノメチル（又はエチル）エーテル等の多価アルコールの低級アルキルエーテル類；Ｎ−メチル−２−ピロリドン、１，３−ジメチル−２−イミダゾリジノン、トリエタノールアミン、スルホラン、ジメチルサルフォオキサイド、２−ピロリドン、ε−カプロラクタム等の環状アミド化合物及びスクシンイミド等のイミド化合物等が挙げられる。
【００４３】
上記水溶性有機溶剤の含有量は、一般にはインクの全重量に対して１〜４０重量％が好ましく、より好ましくは３〜３０重量％の範囲である。
又、インク中の水の含有量は、インクの全重量に対して３０〜９５重量％の範囲で使用される。３０重量％より少ないと染料の溶解性等が悪くなり、インクの粘度も高くなるため好ましくない。一方、９５重量％より多いと蒸発成分が多すぎて、十分な固着特性を満足することができない。
【００４４】
本発明のインクには、インク中の無機イオンである不純物により、例えば、インクジェット記録方法においてコゲという問題を発生させるため、このようなインクの悪影響を防止するためにコゲ防止剤を含有した方がよい。但し、これらのコゲ防止剤も熱エネルギーを伝えるヒーターの表面状態と相関関係があるため、場合によっては未添加でもよい。又、インク中の無機イオンが１ｐｐｍ、好ましくは０．５ｐｐｍ以下であれば添加しなくてもよい。それらのインク中への含有量はインク全重量に対して０．０１〜１０重量％、好ましくは０．０５〜５重量％、更に好ましくは０．１〜３重量％である。
【００４５】
又、本発明のインクは、インク中に尿素、チオ尿素及びそれらの誘導体を含有することが好ましい。これらの物質のインク中への含有量はインク全重量に対して０．１〜５０重量％、好ましくは１〜３０重量％、更に好ましくは２〜１０重量％である。
【００４６】
更に本発明のインクには、インクの定着剤として一価アルコールを添加してもよい。又、非イオン性界面活性剤も定着剤として機能する。これらは異なった色調を印字した場合、その境界で生じる混色滲みを防止するためには必要となる。又、これらは染料のインク中での溶解性を安定向上させるという意味でもインク中に含有している方が好ましい。その場合、インク中への添加量と効果を考えるならば非イオン性界面活性剤の方が好ましい。
【００４７】
定着剤として本発明のインクに添加し得る一価アルコールの具体例としてはエタノール、イソプロピルアルコール及びｎ−ブタノール等が挙げられる。又、同様に添加し得る非イオン性界面活性剤の具体例としては、ポリオキシエチレンアルキルエーテル、ポリオキシエチレンフェニルエーテル、ポリオキシエチレン−ポリオキシプロピレングリコール、ポリオキシエチレン−ポリオキシプロピレンアルキルエーテル、アセチレングリコールポリエチレンオキサイド付加物等が挙げられるが、好ましくはノニルフェニルエーテルＥＯ付加体、エチレンオキサイド−プロピレンオキサイド共重合体（ＥＯ−ＰＯ共重合体）、アセチレングリコールポリオキシエチレンオキサイド付加物が好ましく、より好ましくは下記一般式（Ｖ）で表されるアセチレングリコールポリオキシエチレンオキサイド付加物（アセチレングリコールＥＯ付加物）である。
【００４８】

上記一価アルコール又は非イオン界面活性剤のインクの含有量は、インク全重量に対して０．１〜２０重量％、好ましくは０．５〜１０重量％である。０．１重量％より少ないと定着剤としての効果がなく、又、２０重量％より多いと印字品位のバランス、例えば、濃度や定着性やヒゲ状の滲みであるフェザリングと定着性や濃度とのバランスが悪くなる。
【００４９】
本発明のインクは、熱エネルギーによるインクの発泡現象によりインクを吐出させるタイプのインクジェット記録方法に適用する場合に特に好適であり、吐出が極めて安定となり、サテライトドットの発生等が生じないという特徴がある。但しこの場合には、熱的な物性値（例えば、比熱、熱膨張係数、熱伝導率等）を調整する場合もある。
【００５０】
更に、本発明のインクは普通紙等に記録した場合の印字記録物のインクの耐水性の問題を解決すると同時に、インクジェット用ヘッドに対するマッチングを良好にする面から、インク自体の物性として２５℃における表面張力が２０〜５５ｄｙｎｅ／ｃｍ、粘度が１５ｃＰ以下、好ましくは１０ｃＰ以下、より好ましくは５ｃＰ以下に調整されることが望ましいが、インクジェット記録用ヘッドの性態に左右されるため、これに限定されるものではない。
従って、上記物性にインクを調整し、普通紙における問題を解決するためには、本発明のインク中に含有される水分量としては５０重量％以上９８重量％以下、好ましくは６０重量％以上９５重量％以下とされるのが好適である。
【００５１】
本発明のインクは、熱エネルギーの作用により液滴を吐出させて記録を行なうインクジェット記録方法にとりわけ好適に用いられるが、一般の筆記具用としても使用できる。
本発明のインクを用いて記録を行うのに好適な方法及び装置としては、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、該熱エネルギーにより液滴を発生させる方法及び装置が挙げられる。
【００５２】
その装置の主要部であるヘッド構成例を図１、図２及び図３に示す。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ヘッド１５（図では薄膜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、蓄熱層１９、アルミナ等の放熱性の良い基板２０とによりなっている。
【００５３】
インク２１は吐出オリフィス（微細孔）２２まで来ており、圧力Ｐによりメニスカス２３を形成している。
今、アルミニウム電極１７−１及び１７−２に電気信号が加わると、発熱ヘッド１５のｎ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に気泡が発生し、その圧力でメニスカス２３が突出し、インク２１が吐出し、オリフィス２２よりインク小滴２４となり、被記録材２５に向かって飛翔する。
図３には図１に示すヘッドを多数並べたマルチヘッドの外観図を示す。該マルチヘッドはマルチ溝２６を有するガラス板２７と、図１に説明したものと同様な発熱ヘッド２８を密着して製作されている。尚、図１は、インク流路に沿ったヘッド１３の断面図であり、図２は図１のＡ−Ｂ線での切断面である。
【００５４】
図４に、かかるヘッドを組み込んだインクジェット記録装置の１例を示す。図４において、６１はワイピング部材としてのブレードであり、その一端はブレード保持部材によって保持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６５による記録領域に隣接した位置に配設され、又、本例の場合、記録ヘッド６５の移動経路中に突出した形態で保持される。
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、インク吐出口面と当接し、キャッピングを行う構成を備える。更に６３はブレード６１に隣接して設けられるインク吸収体であり、ブレード６１と同様、記録ヘッド６５の移動経路中に突出した形態で保持される。上記ブレード６１、キャップ６２及びインク吸収体６３によって吐出回復部６４が構成され、ブレード６１及びインク吸収体６３によってインク吐出口面の水分、塵埃等の除去が行われる。
【００５５】
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であり、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と慴動可能に係合し、キャリッジ６６の一部はモーター６８によって駆動されるベルト６９と接続（不図示）している。これによりキャリッジ６６はガイド軸６７に沿った移動が可能となり、記録ヘッド６５による記録領域及びその隣接した領域の移動が可能となる。
５１は被記録材を挿入するための給紙部、５２は不図示のモーターにより駆動される紙送りローラーである。これらの構成によって記録ヘッド６５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ー５３を配した排紙部へ排紙される。
【００５６】
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、吐出回復部６４のキャップ６２は記録ヘッド６５の移動経路から退避しているが、ブレード６１は移動経路中に突出している。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に突出するように移動する。
【００５７】
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は上述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。
上述の記録ヘッドのホームポジションへの移動は、記録終了時や吐出回復時ばかりでなく、記録ヘッドが記録のために記録領域を移動する間に所定の間隔で記録領域に隣接したホームポジションへ移動し、この移動に伴って上記ワイピングが行われる。
【００５８】
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の一例を示す図である。ここで４０は供給用インクを収容したインク収容部、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ならしめる。４４は廃インクを受容するインク吸収体である。インク収容部としては、インクとの接液面がポリオレフィン、特にポリエチレンで形成されているものが本発明にとって好ましい。本発明で使用されるインクジェット記録装置としては、上記の如き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に示す如きそれらが一体になったものにも好適に用いられる。
【００５９】
図６において、７０は記録ユニットであって、この中にはインクを収容したインク収容部、例えば、インク吸収体が収納されており、かかるインク吸収体中のインクが複数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。インク吸収体の材料としては、ポリウレタン、セルロース又はポリビニルアセタールを用いることが本発明にとって好ましい。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で示す記録ヘッドに代えて用いられるものであって、キャリッジ６６に対し着脱自在になっている。
【００６０】
本発明のインクは、好ましい条件として、アニオン性の溶解又は分散タイプの化合物を併用させているため、インクのｐＨは８以上が好ましい。しかしながら、インクジェット記録方法に用いた場合、吐出性等の信頼性等を考えるとｐＨは８．５以上、更に好ましくは９．０以上である。又、本発明のインクは、含窒素化合物や２価の金属でｐＨを調整してもよい。
尚、本発明のインクは、上記成分の他に必要に応じて水溶性有機溶剤、界面活性剤、防錆剤、防カビ剤、酸化防止剤、蒸発促進剤、キレート化剤、水溶性ポリマー等の種々の添加剤を添加してもよい。
【００６１】
【実施例】
次に、実施例及び比較例を挙げて、本発明を更に具体的に説明する。尚、文中「部」及び「％」と表示のあるものは、特に断りのない限り重量基準である。
【００６２】
実施例１〜４及び比較例１〜３
＜インクの作製＞
下記に示す各成分を混合し、十分攪拌して溶解後、ポアサイズが０．４μｍのフロロポアフィルター（商品名：住友電工（株）製）にて加圧濾過し、本発明及び比較例のインクを夫々調製した。
【００６３】
実施例１
C.I.ダイレクトブラック１９５（染料２３）３．０％
チオジグリコール １０．０％
ジエチレングリコール １０．０％
分子量５，０００のポリアクリル酸アンモニウム塩
１．０％
純水 ７６．０％
【００６４】
実施例２
C.I.ダイレクトブラック１９５（染料２３）２．５％
グリセリン １０．０％
イソプロピルアルコール ３．０％
分子量５，０００のポリアクリル酸
トリエタノールアミン塩 ０．５％
分子量１０，０００のポリアクリル酸
ナトリウム塩 ０．４％
純水 ８５．４％
【００６５】
実施例３
染料５ ３．０％
２−ピロリドン １０．０％
エタノール ４．０％
分子量７，８００のポリアクリル酸
トリエタノールアミン塩 １．０％
分子量３，０００のポリアクリル酸
アンモニウム塩 １．０％
一般式（Ｖ）の化合物
（式中、ａ＝ｂ＝１、ｍ＋ｎ＝１５） １．０％
純水 ８０．０％
【００６６】
実施例４
染料１ ２．５％
グリセリン ７．０％
尿素 １０．０％
エタノール ３．０％
分子量５，０００のポリアクリル酸
アンモニウム塩 ２．０％
純水 ７５．５％
【００６７】
比較例１
C.I.ダイレクトブラック１９５（染料２３）３．０％
チオジグリコール １０．０％
ジエチレングリコール １０．０％
純水 ７７．０％
【００６８】
比較例２
C.I.ダイレクトブラック５１（染料２４） ２．０％
チオジグリコール １０．０％
ジエチレングリコール １０．０％
分子量５，０００のポリアクリル酸
アンモニウム塩 １．０％
純水 ７６．０％
【００６９】
比較例３
Ｃ．Ｉ．フードブラック２ ３．０％
グリセリン １０．０％
イソプロピルアルコール ３．０％
分子量１０，０００のポリアクリル酸
ナトリウム塩 １．０％
純水 ８３．０％
【００７０】
＜流動性の確認＞
得られた各インクについて、その流動性を以下の方法により確認した。
【００７１】
（１）流動性（Ａ）
１００ｃｃガラスビーカーに試料インク１００ｇを入れ、６０℃、２０％ＲＨ環境のオーブンに５日間放置した後の状態を、下記基準で評価した。
【００７２】
（２）流動性（Ｂ）
１００ｃｃガラスビーカーに試料インク１００ｇを入れ、６０℃、２０％ＲＨ環境のオーブンに５日間放置した後、該ガラスビーカーを更に２５℃環境に５日間放置した後の状態を、下記基準で評価した。
○：インク表面に析出物は認められず、且つインク内部は流動性があった。又、ビーカーを逆さまにすると、インクが流れ落ちた。
△：インク表面に析出物が認められるが、インク内部は流動性はある。しかし、インクは粘稠な状態である。又、ビーカーを逆さまにしてもインクは流れ落ちなかった。
×：インク表面に析出物は認められ、且つインク内部も表面と同じ様な状態で、流動性が見られなかった。又、ビーカーを逆さまにしてもインクは流れ落ちなかった。
【００７３】
＜評価試験＞
次に、上記で得られた実施例１〜４及び比較例１〜３のインクについて、インクジェット記録装置として、発熱素子をインクの吐出エネルギー源として利用したＢＪＣ−６００Ｊ（商品名：キヤノン（株）製）を用いて、以下の各評価を行い、その結果を表１にまとめた。
【００７４】
＜評価方法及び評価基準＞
（１）耐水性
プリンターに所定のインクを充填して、市販の酸性紙に英数文字及びベタ部を印字した後、プリントを停止し、印字物を１時間以上放置後、印字濃度をマクベスＲＤ９１５（商品名：マクベス社製）にて測定を行う。その後、印字物を水を満たした容器に３分間以上浸漬した後、放置、乾燥して再度印字濃度を測定し、印字物濃度の残存率を求め、耐水性の評価とした。
○：印字物濃度の残存率が８０％以上。
△：印字物濃度の残存率が６５％以上〜８０％未満。
×：印字物濃度の残存率が６５％未満。
【００７５】
（２）周波数応答性
得られた印字物の印字状態、即ちカスレや白抜け状態及びスブラッシュやヨレ等の着弾点不良状態を肉眼で観察し、評価した。
○：周波数に対するインクの追従状態は、ほぼ良好であり、キャラクタ印字ではカスレや白抜け、着弾点不良が見られないが、ベタ印字において僅かにカスレが見られる。
△：キャラクタ印字ではカスレや白抜けは見られないが、一部に着弾点不良が見られる。又、ベタ印字ではカスレ、白抜けがベタ印字全体の１/３程度で見られる。
×：ベタ印字ではカスレ、白抜けが多く、又、キャラクタ印字においてもカスレや着弾点不良が多数見られる。
【００７６】
（３）印字品位の評価
プリンターで市販の普通紙紙に英数文字を印字し、印字物を１時間以上放置した後、顕微鏡及び目視で文字のシャープさや文字より発生するヒゲ状の滲みの度合いを評価した。
◎：文字がシャープでヒゲ状の滲みがない。
○：文字がシャープであるが、ヒゲ状の滲みが少し発生。
△：文字にシャープさがない。又は、ヒゲ状の滲みがやや多い。
×：文字にシャープさがなく、ヒゲ状の滲みも多い。
【００７７】
（４）耐目詰り性の評価
ＢＪＣ６００に各々のインクを充填し、５０℃の環境に１週間放置し、正常に吐出するまでの回復操作の回数により、耐目詰り性を以下の基準で評価した。
○：回復操作５回以内で正常な吐出をした。
△：回復操作６回〜１０回で正常な吐出をした。
×：回復操作１１回でも正常な吐出をしなかった。
【００７８】
（５）固着性の評価
ＢＪＣ６００に各々のインクを充填し、５０℃の環境に１週間放置後、そのまま５℃の環境に１週間放置して、正常に吐出するまでの回復操作の回数により、固着性を以下の基準で評価した。
○：回復操作５回以内で正常な吐出をした。
△：回復操作６回〜１０回で正常な吐出をした。
×：回復操作１１回でも正常な吐出をしなかった。
【００７９】
表１：実施例及び比較例の評価結果

【００８０】
【発明の効果】
以上説明したように、本発明によれば、一般オフィス等で用いられている普通紙に対して印字記録をした場合、高品位な画像が得られ、且つインクの安定性、信頼性に優れ、耐水性も良好なインク、これを用いたインクジェット記録方法及びかかるインクを用いた機器を提供することができる。
更に、本発明によれば、長期間の保存後も安定性が良好であり、インクジェット記録システムに用いても、何ら問題のない信頼性の高い記録を行い得るインク、これを用いたインクジェット記録方法及びかかるインクを用いた機器を提供することができる。
【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】図１に示したヘッドをマルチ化したヘッドの外観斜視図である。
【図４】インクジェット記録装置の一例を示す斜視図である。
【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。
【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：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：インク小滴
２５：被記録材
２６：マルチ溝
２７：ガラス板
２８：発熱ヘッド
４０：インク袋
４２：栓
４４：インク吸収体
４５：インクカートリッジ
５１：給紙部
５２：紙送りローラー
５３：排紙ローラー
６１：ワイピング部材
６２：キャップ
６３：インク吸収体
６４：吐出回復部
６５：記録ヘッド
６６：キャリッジ
６７：ガイド軸
６８：モーター
６９：ベルト
７０：記録ユニット
７１：ヘッド部
７２：大気連通口 [0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink, an ink jet recording method using the ink, and an apparatus using the ink. More specifically, when recording is performed on acid paper or neutral paper used in a general office or the like, Ink with which high-quality images can be obtained, excellent ink stability and reliability, and good water resistance, and ink jet recording method using the same, Recording unit, ink cartridgeAndBiiNkJet recording deviceAbout.
[0002]
[Prior art]
Conventionally, inks for writing instruments (fountain pens, sign pens, water-based ballpoint pens, etc.) and inks for ink jet recording have been reported in various compositions. In particular, in recent years, there has been an increasing demand for high-quality printing and improved water resistance on plain paper such as copy paper, report paper, notebooks, and stationery, which are used as recording paper in various fields. In order to meet these demands while maintaining stability and reliability at a high order, detailed research and development has been conducted from various aspects such as ink composition and physical properties.
[0003]
For example, JP-A 63-289081 discloses an ink containing a polycarboxylic acid type polymer surfactant having a molecular weight of 10,000 to 500,000 in the ink, and JP-A-6-93224. Has been proposed for improving the reliability of ink for ballpoint pens, which contains a polycarboxylic acid including a polycarboxylic acid ester and / or a salt thereof, and has a viscosity of 50 to 2,000 cps.
[0004]
However, in each of the above proposals, in a system that performs recording by the action of external energy such as a ballpoint pen, for example, by applying external energy even if the ink is fixed at the tip of the ballpoint pen (in this case, increasing the external pressure) However, in the ink jet recording system, recording is performed by applying internal energy (in this case, energy is applied to the internal ink from the ink discharge unit). When the ink is in a fixed state at the ejection port, it is difficult to increase the internal energy, and sufficient reliability has not been obtained. Furthermore, the water resistance of the recorded matter is insufficient.
[0005]
[Problems to be solved by the invention]
Accordingly, the present invention provides an ink for improving the above problems, and an ink jet recording method using the same, Recording unit, ink cartridgeAndBiiNkJet recording deviceIs to provide.
[0006]
[Means for Solving the Problems]
  The above object is achieved by the present invention described below. That is, according to one embodiment of the present invention, an ink is at least a colorant, water, a liquid medium in which water is dissolved or dispersed,Polyacrylate, a water-soluble polymer compoundIncludingThe colorant contains SO in its chemical structure. _Three In the absence of H groups, it has at least two COOH groups and SO _Three In the case of having an H group, the COOH group is changed to SO. _Three It is equal to or more than the number of H groups and has 2 or more.The entire ink is fluid in a state where water in the ink is evaporated in an environment of 60 ° C.ThereIt is the ink characterized by this.It should be noted that water-soluble polymer compounds and coloring materials other than those described in the present specification are not included in the present invention.
  Another embodiment of the present invention uses an ink described above as an ink in an ink jet recording method in which ink is ejected from an orifice of a recording head in accordance with a recording signal and recording is performed on a recording material. Ink jet recording method.
  According to another embodiment of the present invention, there is provided a recording unit comprising an ink containing portion containing ink and a head portion for ejecting ink, wherein the ink is the ink described above for inkjet. Is a unit.
  Furthermore, another embodiment of the present invention is an ink cartridge provided with an ink storage portion that stores ink, wherein the ink is the ink described above.
  According to another embodiment of the present invention, there is provided an ink jet recording apparatus comprising a recording unit having an ink containing portion containing ink and a head portion for discharging the ink, wherein the recording unit is the recording unit described above. This is an ink jet recording apparatus.
  Furthermore, another embodiment of the present invention includes a recording head for ejecting ink, an ink cartridge having an ink storage portion for storing ink, and an ink supply portion for supplying ink from the ink cartridge to the recording head. Further, in the ink jet recording apparatus, the ink cartridge is the ink cartridge described above.
[0007]
According to the present invention, an ink in which clogging at the nozzle tip is remarkably reduced even under poor environmental conditions such as a high temperature environment, a low temperature environment, and a high temperature / low temperature mixed environment, and an ink jet recording method using the ink, Recording unit, ink cartridgeAndBiiNkJet recording deviceIs provided.
The exact reason why the ink of the present invention can obtain high reliability against clogging in a poor environment such as a high temperature environment, a low temperature environment and a mixed environment of high temperature and low temperature is unknown, The reason is described in the scope of speculation.
[0008]
In general, a water-soluble ink using a color material which is a solid is used at a saturation concentration or less with respect to the liquid medium of the water-soluble ink of the color material. When a large amount of water in the water-soluble ink evaporates, the concentration of the color material with respect to the ink becomes equal to or higher than the saturation concentration, the color material is precipitated, and further, when the water evaporation proceeds, the color material starts to harden. However, in the ink of the present invention, even when the concentration of the color material in the ink exceeds the saturated concentration, the association of the color material is suppressed, so that the color material does not precipitate and the water in the ink evaporates. Even so, the coloring material does not start to solidify, and it is estimated that high reliability against clogging and the like can be obtained.
[0009]
If the recording system is such that the recording system is in direct contact with the recording material such as a ballpoint pen, even if the ink is once clogged at the ejection port, it is caused by friction with the recording material during recording. Clogging can be removed by external energy, but in the inkjet recording system, which does not have such a function, water in the ink normally evaporates from the ink ejection port, causing a large amount of color material to be clogged. Can not be removed. However, even in such a case, if the ink of the present invention is used, the coloring material in the ink does not associate within the ejection port and the ejection port, so that the coloring material does not precipitate or clog, that is, the ink. Since the liquid is kept in a liquid state, it becomes possible to make the energy for the ink generated for discharging the ink inside the ink discharge port to function well, and the good ink discharge property, in other words, good recording property. It is speculated that clogging resistance may be improved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
  Next, the present invention will be described in more detail with reference to embodiments.
  The ink of the present invention is fluid in its entirety in a state where water in the ink is evaporated in an environment of 60 ° C.ThereIt is characterized by that. In addition, the ink of the present invention comprises at least an initial component of a color material, water, and a liquid medium that dissolves or disperses in water.The
[0011]
The ink of the present invention is preferably one that does not generate floating precipitates at the gas-liquid interface in a state where water in the ink is evaporated in a 60 ° C. environment. This is because, for example, when the ink of the present invention is used in an ink jet recording method, the apparatus used in the method has a very small ejection port for ejecting the ink, and the ink ejection is performed in order to improve the ink ejection. The periphery of the discharge port is covered with a water repellent, but if a solid deposit such as a coloring material is floating even at the gas-liquid interface of the ink discharge port, this suspended matter will become the edge of the discharge port. This is because it may adhere to the ink and deteriorate the discharge performance.
[0012]
In addition, the ink of the present invention has fluidity in a state where water in the ink is evaporated in an environment of 60 ° C., and the viscosity of the ink in that state is not allowed to stand in the environment of 60 ° C. More preferably, it is 600 times or less of the initial viscosity of the ink.
This is because, for example, in the ink jet recording method, in order to suppress clogging and fixing of the ink, the recovery device performs discharge for clogging recovery or sucks ink from the discharge port surface to the device itself. However, if the viscosity of the ink in the state where the water in the ink is evaporated in an environment of 60 ° C. becomes too large, energy is applied to the ink when discharging for recovery from clogging. This is because the energy is absorbed by the viscosity of the ink and the target ejection cannot be performed, or the recovery device cannot operate to the recovery level.
Therefore, due to the correlation between the ink and a recording system such as an ink jet recording system, the viscosity of the ink in a state where water in the ink is evaporated in an environment of 60 ° C. is 600 times or less of the initial viscosity of the ink. It is preferable.
[0013]
On the other hand, the ink of the present invention has fluidity as a whole when the water in the ink is evaporated in an environment of 60 ° C., and the initial components of the ink are at least a colorant, water, and water. Or a liquid medium that disperses, and the fluidity of the ink as a whole is not lost even when the ink is left to stand again in a 25 ° C. environment after evaporation of moisture in the ink in a 60 ° C. environment. preferable. This is because, for example, when the ink of the present invention is used in an ink jet recording method, preheating is generally performed in order to improve the ink discharge performance while the entire apparatus used in the method is energized. This is because the temperature condition varies depending on the recording system, but generally a temperature of about 25 ° C. to 35 ° C. is applied.
[0014]
That is, for example, even in a poor environment such as 60 ° C., even if the ink has fluidity in a state where moisture in the ink is evaporated from the ink discharge port, the ink is then placed in a low temperature environment such as 10 ° C. or less. Thus, even when almost no external energy for dissolving each compound in the ink is applied, the ink is placed at an environmental temperature of about 25 to 35 ° C. by the preheating operation in the ink jet recording method. Even if the water content in the ink is evaporated in a 25 ° C environment, the fluidity of the entire ink is not lost even if it is left in the 25 ° C environment, but it has excellent ink ejection stability and clogging resistance. It becomes.
[0015]
Further, in the ink of the present invention, a water-soluble polymer compound having a plurality of water-soluble groups having at least one selected from phosphoric acid, sulfonic acid or carboxylic acid in a free acid state is used in combination with a coloring material. It is preferable.
In view of the long-term stability of the ink, the environment in which the ink is placed (high and low temperatures), the pH of the ink, and the like, the water-soluble polymer compound particularly preferably has no ester bond. This is because there is a possibility that the ester bond breaks in the environment as described above and alcohol is generated, and the ink having the water-soluble polymer compound having the ester bond is left in the environment. This is because, when recording is performed using the ink, the quality of the recorded image may be deteriorated although it depends on the design of the ink.
[0016]
The water-soluble polymer compound preferably has only an anionic polarity. This is because if the compound has a cationic property, it may react within the compound itself depending on the environment surrounding the ink.
[0017]
The above water-soluble polymer compound depends on the design and intended purpose of the ink, but preferably has a molecular weight in the range of 2,000 to 12,000. When the molecular weight is less than 2,000, the stability of the water-soluble polymer compound is low, and when the molecular weight exceeds 12,000, for example, when used in an ink jet recording system, the viscosity is excessively increased. A malfunction occurs.
In addition, when the water-soluble polymer compound is made into a salt form, the reason is fixed.OrHowever, if two or more types of counter ions are used, ink jet recording suitability is further improved.
[0018]
The color material used in the present invention is preferably an anionic dissolution type color material. This is because, for example, the water-soluble polymer compound preferably used in the present invention is an anionic dissolution type, so that the entire ink flows in a state where water in the ink is evaporated in an environment of 60 ° C. This is because repulsion between the same polarities is considered necessary in order to have the property. However, in order for the whole ink to have fluidity, it is not only due to the repulsion between the same polarities described above, but the same type of color material has fluidity and does not have fluidity. Is not understood. However, a coloring material having the same water-soluble group as that used in the water-soluble polymer compound is preferable.
In the above, it is more preferable that the same water-soluble group as that of the water-soluble polymer compound included in the color material is more than half of the total number of water-soluble groups of the color material.
[0019]
Specific examples of the coloring material as described above are shown below, but the present invention is not limited to these specific examples.
Color material represented by the following general formula (I) in the state of a free acid
Ar¹N = NJX (NR¹LNR²X)_nJN = NAr²    (I)
(In the formula, J represents the following formula.

Ar¹And Ar²Each independently represents an aryl group or a substituted aryl group, and Ar¹And Ar²At least one of them has one or more substituents independently selected from COOH and COSH. R¹And R²Independently represents H, an alkyl group, a substituted alkyl group, an alkenyl group or a substituted alkenyl group, L represents a divalent organic linking group, and n represents 0 or 1. X represents each independently a carbonyl group or a group represented by the following formulas (1) to (3).
[0020]

(Z is independently NR^ThreeR^Four, SR^FiveOr OR^FiveY represents H, Cl, Z, SR⁶Or OR⁶And E represents Cl or CN. R^Three, R^Four, R^FiveAnd R⁶Each independently represents H, an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an aryl group, a substituted aryl group, an aralkyl group, or a substituted aralkyl group;^ThreeOr R^FourMay form a 5- or 6-membered ring with the nitrogen atom. )
Further, the compound represented by the general formula (I) is at least SO._ThreeIt has the same number of groups selected from COOH or COSH as H. )
[0021]
Specific examples of the color material represented by the general formula (I) include the following.

[0022]

[0023]
Colorant represented by the following general formula (II) in the state of free acid

(Wherein Ar and Ar¹Each represents an aryl group or a substituted aryl group, Ar and Ar¹At least one of them has a substituent selected from COOH or COSH. J and J¹Each has a structure selected from the group consisting of the following general formulas (4), (5) and (6)
[0024]

(Wherein R^FiveAre independently H, alkyl group, substituted alkyl group, alkoxy group, halogen, CN, ureido and NHCOR.⁶Selected from. R⁶Is selected from H, an alkyl group, a substituted alkyl group, an aryl group, a substituted aryl group, an aralkyl group and a substituted aralkyl group. T represents an alkyl group, W represents H, CN, CONR^TenR¹¹, Pyridium and COOH. (M) represents an alkylene chain having 2 to 8 carbon atoms, and B is selected from H, an alkyl group and COOH. R^TenAnd R¹¹Are each selected from H, an alkyl group and a substituted alkyl group. ).
[0025]
R¹, R², R^ThreeAnd R^FourAre each selected from H, an alkyl group and a substituted alkyl group, L represents a divalent organic linking group, and n represents 0 or 1. X consists of a carbonyl group or the structure of the following general formula (7), (8) or (9).
[0026]

(Where Z is OR⁷, SR⁷And NR⁸R⁹Y is selected from H, Cl, CN and Z, and E is selected from Cl and CN. R⁷, R⁸And R⁹Are each selected from H, alkenyl group, substituted alkenyl group, alkyl group, substituted alkyl group, aryl group, substituted aryl group, aralkyl group and substituted aralkyl group. R⁸And R⁹May form a 5- or 6-membered ring with the nitrogen atom to which they are attached. )
(1) General formula (II) is SO_ThreeWhen there is no H group, it has at least two groups selected from COOH groups or COSH groups, and (2) the general formula (II) is SO_ThreeIn the case of having an H group, a group selected from a COOH group or a COSH group is at least SO._ThreeHas the same number or more as the number of H groups. )
[0027]
Specific examples of the color material represented by the general formula (II) include the following.

[0028]

[0029]

[0030]

[0031]

[0032]
Color material represented by the following general formula (III) in the form of a free acid:

(Wherein R₁And R₂Are each independently selected from a hydrogen atom, a carboxyl group, a sulfone group and an alkyl group having 1 to 2 carbon atoms, and X and Y are each independently NR_ThreeR_FourAnd NR_FiveR₆Chosen from. R_ThreeAnd R_FourAre each independently selected from alkyl groups, substituted alkyl groups, aryl groups, substituted aryl groups, aralkyl groups, substituted aralkyl groups, alkoxyl groups and substituted alkoxyl groups, and R_FiveIs selected from a hydrogen atom, an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an aralkyl group, a substituted aralkyl group, an alkoxyl group and a substituted alkoxyl group;₆Represents a colorless organic residue substituted with COSH or COOH. )
[0033]
Specific examples of the compound represented by the general formula (III) include the following.

[0034]
Color material represented by the following general formula (IV) in the state of free acid

(In the general formula (IV), R₁, R₂And R₂'Is selected from a carboxyl group, a sulfone group, a hydroxyl group, an amino group, an alkyl group having 1 to 2 carbon atoms, and a hydrogen atom, and R_Three, R_Four, R_FiveAnd R₆Is selected from a carboxyl group, a sulfone group, an amino group, a hydroxyl group, an alkylamide group and a hydrogen atom.
[0035]
X has a structure represented by the following general formula (A) or (B).

(In the above general formulas (A) and (B), R₇Is selected from a carboxyl group, a sulfone group and a hydrogen atom. R₈, R₉Is selected from the group consisting of a carboxyl group, a sulfone group, a structure represented by the following formula, and hydrogen.

(In the above formula, n represents an integer of 1 to 5, and m represents 0 or 1, respectively.))
[0036]
Specific examples of the color material represented by the general formula (IV) include the following.
[0037]

[0038]

[0039]

[0040]

[0041]
  Of the above-described exemplary compounds, the chemical structure includes SO. _Three In the absence of H groups, it has at least two COOH groups and SO _Three In the case of having an H group, the COOH group is changed to SO. _Three As the coloring material having the same number or more as the number of H groups and 2 or more, dyes 1 to 23 and 26 are applicable.Further, the coloring material used in the present invention is the same kind of the water-soluble base species of the coloring material in the free acid state and the water-soluble base species of the water-soluble polymer compound, and the above color When the number of water-soluble groups in the material is the same as or more than the number of other water-soluble groups in the color material, the reliability tends to be better. Further, taking into consideration the improvement in water resistance and the like of the recorded matter, it is particularly preferable that the water-soluble group in the above case is a carboxylic acid in the state of a free acid.
[0042]
The liquid medium used in the present invention is preferably a mixture of water and a water-soluble organic solvent. Specific examples of the water-soluble organic solvent include amides such as dimethylformamide and dimethylacetamide; ketones such as acetone; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms, such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol; glycerin Ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether, etc. Lower alkyl ethers of polyhydric alcohols; cyclic such as N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, triethanolamine, sulfolane, dimethyl sulfoxide, 2-pyrrolidone, ε-caprolactam Examples include amide compounds and imide compounds such as succinimide.
[0043]
The content of the water-soluble organic solvent is generally preferably 1 to 40% by weight, more preferably 3 to 30% by weight, based on the total weight of the ink.
Further, the water content in the ink is used in the range of 30 to 95% by weight with respect to the total weight of the ink. If it is less than 30% by weight, the solubility of the dye is deteriorated and the viscosity of the ink is also increased, which is not preferable. On the other hand, if it exceeds 95% by weight, there are too many evaporation components, and sufficient fixing characteristics cannot be satisfied.
[0044]
The ink of the present invention may cause a problem of kogation in the ink jet recording method due to impurities that are inorganic ions in the ink. Therefore, it is better to contain an anti-kogation agent in order to prevent such an adverse effect of the ink. Good. However, since these kogation inhibitors also have a correlation with the surface state of the heater that transmits thermal energy, they may not be added in some cases. Further, if the inorganic ion in the ink is 1 ppm, preferably 0.5 ppm or less, it may not be added. The content thereof in the ink is 0.01 to 10% by weight, preferably 0.05 to 5% by weight, more preferably 0.1 to 3% by weight, based on the total weight of the ink.
[0045]
The ink of the present invention preferably contains urea, thiourea and derivatives thereof in the ink. The content of these substances in the ink is 0.1 to 50% by weight, preferably 1 to 30% by weight, more preferably 2 to 10% by weight, based on the total weight of the ink.
[0046]
Furthermore, a monohydric alcohol may be added to the ink of the present invention as an ink fixing agent. Nonionic surfactants also function as fixing agents. These are necessary in order to prevent mixed color bleeding that occurs at the boundary when different tones are printed. These are also preferably contained in the ink in order to stably improve the solubility of the dye in the ink. In that case, a nonionic surfactant is preferred in view of the amount added to the ink and the effect.
[0047]
Specific examples of the monohydric alcohol that can be added to the ink of the present invention as a fixing agent include ethanol, isopropyl alcohol, and n-butanol. Specific examples of the nonionic surfactant that can be added in the same manner include polyoxyethylene alkyl ether, polyoxyethylene phenyl ether, polyoxyethylene-polyoxypropylene glycol, polyoxyethylene-polyoxypropylene alkyl ether, Examples include acetylene glycol polyethylene oxide adducts, preferably nonylphenyl ether EO adducts, ethylene oxide-propylene oxide copolymers (EO-PO copolymers), and acetylene glycol polyoxyethylene oxide adducts. Preferably, it is an acetylene glycol polyoxyethylene oxide adduct (acetylene glycol EO adduct) represented by the following general formula (V).
[0048]

The content of the monohydric alcohol or nonionic surfactant ink is 0.1 to 20% by weight, preferably 0.5 to 10% by weight, based on the total weight of the ink. If it is less than 0.1% by weight, there is no effect as a fixing agent, and if it is more than 20% by weight, the balance of print quality, for example, feathering that is density and fixability or whiskers, fixing property and density, etc. The balance becomes worse.
[0049]
The ink of the present invention is particularly suitable when applied to an ink jet recording method in which ink is ejected due to an ink bubbling phenomenon caused by thermal energy, and is characterized in that ejection is extremely stable and generation of satellite dots does not occur. is there. In this case, however, thermal property values (for example, specific heat, thermal expansion coefficient, thermal conductivity, etc.) may be adjusted.
[0050]
Furthermore, the ink of the present invention solves the problem of water resistance of the ink of the printed matter when recorded on plain paper, etc., and at the same time, the physical properties of the ink itself at 25 ° C. It is desirable to adjust the surface tension to 20 to 55 dyne / cm and the viscosity to 15 cP or less, preferably 10 cP or less, more preferably 5 cP or less, but it is limited to this because it depends on the properties of the inkjet recording head. It is not something.
Therefore, in order to adjust the ink to the above physical properties and solve the problem in plain paper, the amount of water contained in the ink of the present invention is 50% by weight to 98% by weight, preferably 60% by weight to 95%. It is preferable that the amount is not more than wt%.
[0051]
The ink of the present invention is particularly suitably used in an ink jet recording method in which recording is performed by discharging droplets by the action of thermal energy, but can also be used for general writing instruments.
As a method and apparatus suitable for performing recording using the ink of the present invention, there is a method and apparatus for applying thermal energy corresponding to a recording signal to ink in a recording head chamber and generating droplets by the thermal energy. Can be mentioned.
[0052]
An example of a head configuration which is a main part of the apparatus is shown in FIGS. The head 13 includes a glass, ceramic or plastic plate having a groove 14 through which ink passes, and a heat generating head 15 (though a thin film head is shown in the figure, but is not limited to this) used for thermal recording. Obtained by bonding. The heat generating head 15 includes 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 heat storage layer 19, and a substrate 20 with good heat dissipation such as alumina. It is due to.
[0053]
The ink 21 reaches the ejection orifice (fine hole) 22, and a meniscus 23 is formed by the pressure P.
Now, when an electrical signal is applied to the aluminum electrodes 17-1 and 17-2, the region indicated by n of the heat generating head 15 suddenly generates heat, and bubbles are generated in the ink 21 in contact therewith. 23 protrudes, the ink 21 is ejected, becomes an ink droplet 24 from the orifice 22, and flies toward the recording material 25.
FIG. 3 shows an external view of a multi-head in which a large number of heads shown in FIG. 1 are arranged. The multi-head is manufactured by adhering a glass plate 27 having multi-grooves 26 and a heating head 28 similar to that described in FIG. 1 is a cross-sectional view of the head 13 along the ink flow path, and FIG. 2 is a cross-sectional view taken along line AB in FIG.
[0054]
FIG. 4 shows an example of an ink jet recording apparatus incorporating such a head. In FIG. 4, reference numeral 61 denotes a blade as a wiping member. One end of the blade 61 is held by a blade holding member to become a fixed end, and forms a cantilever. The blade 61 is disposed at a position adjacent to the recording area by the recording head 65, and in this example, is held in a form protruding in the moving path of the recording head 65.
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 to come into contact with the ink discharge port surface and perform capping. Further, reference numeral 63 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 65. The blade 61, the cap 62, and the ink absorber 63 constitute a discharge recovery portion 64, and the blade 61 and the ink absorber 63 remove moisture, dust, and the like on the ink discharge port surface.
[0055]
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. Reference numeral 66 denotes a recording head 65 having the recording head 65 mounted thereon. 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 (not shown) driven by a motor 68. As a result, the carriage 66 can move along the guide shaft 67, and the recording area and its adjacent area can be moved by the recording head 65.
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 opening surface of the recording head 65, and is discharged to a paper discharge portion provided with a paper discharge roller 53 as recording progresses.
[0056]
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 ejection recovery unit 64 is retracted from the moving path of the recording head 65, but the blade 61 protrudes into the moving path. As a result, the ejection port 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.
[0057]
When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are in the same position as the above-described wiping position. As a result, the ejection port surface of the recording head 65 is wiped even during this movement.
The above-mentioned movement of the recording head to the home position is not only at the end of recording or at the time of ejection recovery, but also to the home position adjacent to the recording area at a predetermined interval while the recording head moves the recording area for recording. Then, the wiping is performed with this movement.
[0058]
FIG. 5 is a diagram illustrating an example of an ink cartridge 45 that contains ink supplied to the head via an ink supply member, for example, a tube. Reference numeral 40 denotes an ink container, for example, an ink bag, which contains ink for supply, 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. The ink container preferably has an ink contact surface made of polyolefin, particularly polyethylene. The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separated as described above, but is preferably used in an apparatus in which they are integrated as shown in FIG.
[0059]
In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink storage portion that stores ink, for example, an ink absorber is stored, and the ink in the ink absorber has a plurality of orifices. 71 is ejected as ink droplets. As the material of the ink absorber, it is preferable for the present invention to use polyurethane, cellulose, or polyvinyl acetal. 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 shown in FIG. 4 and is detachable from the carriage 66.
[0060]
In the ink of the present invention, since an anionic dissolution or dispersion type compound is used in combination as a preferable condition, the pH of the ink is preferably 8 or more. However, when used in an ink jet recording method, the pH is 8.5 or more, more preferably 9.0 or more in consideration of reliability such as ejection properties. In addition, the pH of the ink of the present invention may be adjusted with a nitrogen-containing compound or a divalent metal.
In addition to the above components, the ink of the present invention may contain a water-soluble organic solvent, a surfactant, a rust inhibitor, a fungicide, an antioxidant, an evaporation accelerator, a chelating agent, a water-soluble polymer, etc. Various additives may be added.
[0061]
【Example】
Next, the present invention will be described more specifically with reference to examples and comparative examples. In the text, “parts” and “%” are based on weight unless otherwise specified.
[0062]
Examples 1-4 and Comparative Examples 1-3
<Preparation of ink>
The following components were mixed, sufficiently stirred and dissolved, and then filtered under pressure with a fluoropore filter (trade name: manufactured by Sumitomo Electric Co., Ltd.) having a pore size of 0.4 μm. The inks of the present invention and comparative examples Were prepared respectively.
[0063]
Example 1
  C.I.Direct Black 195(Dye 23)3.0%
  Thiodiglycol 10.0%
  Diethylene glycol 10.0%
  Polyacrylic acid ammonium salt with a molecular weight of 5,000
                                          1.0%
  Pure water 76.0%
[0064]
Example 2
  C.I.Direct Black 195(Dye 23)2.5%
  Glycerin 10.0%
  Isopropyl alcohol 3.0%
  Polyacrylic acid with a molecular weight of 5,000
    Triethanolamine salt 0.5%
  Polyacrylic acid with a molecular weight of 10,000
    Sodium salt 0.4%
  Pure water 85.4%
[0065]
Example 3
Dye 5 3.0%
2-pyrrolidone 10.0%
Ethanol 4.0%
Polyacrylic acid with a molecular weight of 7,800
Triethanolamine salt 1.0%
Polyacrylic acid with a molecular weight of 3,000
Ammonium salt 1.0%
Compound of general formula (V)
(Where, a = b = 1, m + n = 15) 1.0%
Pure water 80.0%
[0066]
Example 4
Dye 1 2.5%
Glycerol 7.0%
Urea 10.0%
Ethanol 3.0%
Polyacrylic acid with a molecular weight of 5,000
Ammonium salt 2.0%
Pure water 75.5%
[0067]
Comparative Example 1
  C.I.Direct Black 195(Dye 23)3.0%
  Thiodiglycol 10.0%
  Diethylene glycol 10.0%
  Pure water 77.0%
[0068]
Comparative Example 2
  C.I.Direct Black 51(Dye 24)  2.0%
  Thiodiglycol 10.0%
  Diethylene glycol 10.0%
  Polyacrylic acid with a molecular weight of 5,000
  Ammonium salt 1.0%
  Pure water 76.0%
[0069]
Comparative Example 3
C. I. Food Black 2 3.0%
Glycerin 10.0%
Isopropyl alcohol 3.0%
Polyacrylic acid with a molecular weight of 10,000
Sodium salt 1.0%
Pure water 83.0%
[0070]
<Confirmation of fluidity>
About each obtained ink, the fluidity | liquidity was confirmed with the following method.
[0071]
(1) Fluidity (A)
100 g of sample ink was put in a 100 cc glass beaker and the state after being left in an oven at 60 ° C. and 20% RH for 5 days was evaluated according to the following criteria.
[0072]
(2) Fluidity (B)
100 g of sample ink was put into a 100 cc glass beaker and left in an oven at 60 ° C. and 20% RH for 5 days, and then the state after the glass beaker was further left in an environment at 25 ° C. for 5 days was evaluated according to the following criteria.
○: No precipitate was observed on the ink surface, and the inside of the ink was fluid. Also, when the beaker was turned upside down, the ink flowed down.
Δ: Precipitates are observed on the ink surface, but the inside of the ink is fluid. However, the ink is in a viscous state. Also, even if the beaker was turned upside down, the ink did not flow down.
X: Precipitates were observed on the ink surface, and the fluid inside was not observed in the same state as the surface inside the ink. Also, even if the beaker was turned upside down, the ink did not flow down.
[0073]
<Evaluation test>
Next, for the inks of Examples 1 to 4 and Comparative Examples 1 to 3 obtained above, BJC-600J (trade name: Canon Inc.) using a heating element as an ink ejection energy source as an ink jet recording apparatus. The following evaluations were performed using the product, and the results are summarized in Table 1.
[0074]
<Evaluation method and evaluation criteria>
(1) Water resistance
After filling the printer with specified ink and printing alphanumeric characters and solid parts on commercially available acid paper, stop printing, leave the printed matter for more than 1 hour, and then set the print density to Macbeth RD915 (trade name: Macbeth Measured at a manufacturer. Then, after immersing the printed matter in a container filled with water for 3 minutes or more, the printed matter was left standing, dried and measured again to determine the remaining density of the printed matter, and the water resistance was evaluated.
○: Residual rate of printed matter density is 80% or more.
Δ: Residual rate of printed matter density is 65% or more and less than 80%.
X: Residual rate of printed matter density is less than 65%.
[0075]
(2) Frequency response
The printed state of the obtained printed matter, that is, the blurred state, the white-out state, and the poor landing point state such as slush or twist, was observed and evaluated with the naked eye.
◯: The ink follow-up state with respect to the frequency is almost good, and no blurring, white spots, or landing point defects are observed in character printing, but slight blurring is observed in solid printing.
Δ: No blur or white spot is seen in character printing, but some landing points are defective. In solid printing, blurring and white spots are seen in about 1/3 of the whole solid printing.
X: There are many spots and white spots in solid printing, and many spots and defective landing points are seen in character printing.
[0076]
(3) Evaluation of print quality
Alphanumeric characters were printed on commercially available plain paper with a printer, and the printed matter was allowed to stand for 1 hour or longer. Then, the sharpness of the characters and the degree of whiskers generated from the characters were evaluated with a microscope and visually.
A: The letters are sharp and there is no whiskers.
○: Characters are sharp, but some whiskers are generated.
Δ: The character is not sharp. Or there is a little amount of whiskers.
X: Characters are not sharp and there are many whiskers.
[0077]
(4) Evaluation of clogging resistance
BJC600 was filled with each ink, left in a 50 ° C. environment for 1 week, and the clogging resistance was evaluated according to the following criteria based on the number of recovery operations until normal ejection.
○: Normal ejection was performed within 5 recovery operations.
(Triangle | delta): Normal discharge was carried out by recovery operation 6 to 10 times.
X: Normal discharge was not performed even after 11 recovery operations.
[0078]
(5) Evaluation of adhesion
BJC600 is filled with each ink, left in a 50 ° C. environment for 1 week, then left in a 5 ° C. environment for 1 week, and the sticking property is determined according to the number of recovery operations until normal ejection is performed according to the following criteria. evaluated.
○: Normal ejection was performed within 5 recovery operations.
(Triangle | delta): Normal discharge was carried out by recovery operation 6 to 10 times.
X: Normal discharge was not performed even after 11 recovery operations.
[0079]
Table 1: Evaluation results of Examples and Comparative Examples

[0080]
【The invention's effect】
As described above, according to the present invention, when recording is performed on plain paper used in a general office or the like, a high-quality image is obtained, and the stability and reliability of the ink are excellent. An ink having good water resistance, an ink jet recording method using the ink, and an apparatus using the ink can be provided.
Furthermore, according to the present invention, an ink that has good stability even after long-term storage and can perform highly reliable recording without any problem even when used in an inkjet recording system, and an inkjet recording method using the same And an apparatus using such an ink can be provided.
[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 in which the head shown in FIG.
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.
[Explanation of symbols]
13: Head
14: Groove
15: Heat generating head
16: Protective film
17-1, 17-2: Electrodes
18: Heating resistor layer
19: Thermal storage layer
20: Substrate
21: Ink
22: Discharge orifice
23: Meniscus
24: Ink droplet
25: Recording material
26: Multi groove
27: Glass plate
28: Heat generation 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
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

Claims (20)

The ink includes at least a coloring material, water, a liquid medium that dissolves or disperses in water, and a polyacrylate that is a water-soluble polymer compound, and the coloring material includes SO ₃ H groups in its chemical structure. If not, it has at least two COOH groups, and if it has SO ₃ H groups, it has COOH groups equal to or more than the number of SO ₃ H groups and 2 or more, and in an environment of 60 ° C. in a state where water was evaporated in the ink, the ink entire said ink, characterized in fluidity there Rukoto.   The ink according to claim 1, wherein no precipitate is generated at the gas-liquid interface in a state where water in the ink is evaporated in a 60 ° C. environment.   The viscosity of the ink in a state where the water in the ink is evaporated in a 60 ° C. environment is 600 times or less of the viscosity in the initial state of the ink before the water in the ink is evaporated in a 60 ° C. environment. Item 3. The ink according to Item 1 or 2.   2. The ink according to claim 1, wherein the fluidity of the ink is not lost even if the ink is left again in a 25 ° C. environment from a state where water in the ink is evaporated in a 60 ° C. environment.   5. The ink fluidity is not lost even when the ink is allowed to stand again in a 25 ° C. environment from a state where water in the ink is evaporated in a 60 ° C. environment, and no precipitate is generated at the gas-liquid interface. The ink described.   Even if the ink is left in a 25 ° C. environment again after the moisture in the ink is evaporated in a 60 ° C. environment, the ink does not lose its fluidity and the ink does not lose its fluidity in a 25 ° C. environment. The ink according to claim 4 or 5, wherein the viscosity is 600 times or less of the viscosity in an initial state of the ink before the water in the ink is evaporated in a 60 ° C environment. The ink according to any one of claims 1 to 6, wherein the polyacrylate has a molecular weight in the range of 2,000 to 12,000. The ink according to any one of claims 1 to 7 , wherein the polyacrylate has two or more kinds of salts. The ink according to any one of claims 1-8 wherein the ink is an inkjet. 10. An ink jet recording method, wherein the ink according to claim 9 is used as an ink in an ink jet recording method in which ink is ejected from an orifice of a recording head in accordance with a recording signal and recording is performed on a recording material. Ink by applying thermal energy, the ink jet recording method according to claim 1 0 to eject ink from the orifice. 10. A recording unit comprising an ink containing portion containing ink and a head portion for ejecting ink, wherein the ink is the ink according to claim 9 . Head portion, the recording unit according to claim 1 2 having a head which ink is reacted with thermal energy to eject ink from the orifice. Ink storage portion, a recording unit according to claim 1 2 having an ink-absorbing member therein. The recording unit according to claim 14 , wherein the ink container has an ink absorber made of polyurethane, cellulose, or polyolefin. An ink cartridge comprising an ink container that contains ink, wherein the ink is the ink according to any one of claims 1 to 9 . The ink cartridge according to claim 16 , wherein the ink containing portion has a liquid contact surface formed of polyolefin. The recording unit according to any one of claims 12 to 15 , wherein the recording unit includes an ink storage unit that stores ink and a recording unit that includes a head unit for ejecting the ink. An ink jet recording apparatus which is a unit. An ink jet recording apparatus comprising: a recording head for ejecting ink; an ink cartridge having an ink containing portion that contains ink; and an ink supply portion for supplying ink from the ink cartridge to the recording head. Item 18. An ink jet recording apparatus comprising the ink cartridge according to Item 16 or 17 . The ink jet recording apparatus according to claim 19 , wherein the recording head is a head that causes thermal energy to act on ink and ejects ink from an orifice.

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