JP3544138B2 - Ink, ink set, ink cartridge, recording unit, image recording method, image recording apparatus, and method for reducing kogation on heating heater - Google Patents

Description

【００３５】
インク中のＢＨＥＳの含有量は、例えばインク全重量を基準として０．１〜３０重量％、特には１〜２０重量％であることが好ましい。このような範囲とすることで、発熱ヒータ上ヘのコゲ、例えばインク中の色材由来のコゲをより有効に抑制することができる。
【００３６】
（ジカルボン酸、ジカルボン酸の塩、トリカルボン酸及びトリカルボン酸の塩）
ジカルボン酸、ジカルボン酸の塩、トリカルボン酸及びトリカルボン酸の塩の具体例を以下に説明する。ジカルボン酸の具体例としては例えばコハク酸、マレイン酸及びフタル酸等が挙げられる。またトリカルボン酸の具体例としては例えばクエン酸等が挙げられる。更にこれらジカルボン酸及びトリカルボン酸の塩としては、例えば金属、例えばナトリウムの塩等が挙げられる。そして特にクエン酸及びクエン酸ナトリウムの少なくとも一方をＢＨＥＳ及び水溶性の色材を含むインク中に含有させた場合、発熱ヒータ上へのコゲの発生を強力に抑制し、また通常の記録条件の下では発熱ヒータの断線を生じさせることも無く、吐出安定性のより一層の向上に極めて好適に用いることができる。
【００３７】
このような物質のインク中の含有量としては、インク全重量を基準として０．０００１〜０．７重量％、特には０．００２〜０．５重量％とすることが好ましい。この範囲内とすることでより優れた吐出安定性を得ることができる。
【００３８】
（色材／その含有量）
色材としては、水溶性であれば特に限定されるものではないが、例えば従来より公知の水溶性染料、例えば水溶性のアニオン性染料や、直接染料、酸性染料、反応染料等を用いることができる。上記染料のインクにおける含有量としては、記録画像の濃度やインクの吐出特性を考慮すると、インク全重量を基準として例えば ０．５〜１５重量％、特には１〜１２重量％とすることが好ましい。
【００３９】
（水性媒体について）
水性媒体は、上記したジカルボン酸、ジカルボン酸の塩、トリカルボン酸及びトリカルボン酸の塩から選ばれる物質、ＢＨＥＳ、及び水溶性の色材 を溶解状態で保持し、インクとして構成せしめる為のものである。そして水性媒体の構成成分として少なくとも水を含むことが好ましく、また各種のインクの構成成分の溶解性を増す為、或いはインクの各種特性の調整に為に水溶性有機溶剤を混合してもよい。インク全重量に占める水の割合としては、例えば２０〜９５重量％、好ましくは４０〜９５重量％、より好ましくは６０〜９５重量％とすることが好ましい。
【００４０】
（水溶性染料の具体例）
ところで本実施態様にかかるインクの色材に用い得るアニオン性基を含有する水溶性染料としては、例えば、下記の様なものが挙げられる。
【００４１】
（ブラックインク）
ブラックインクに用いられる染料としては、例えば、Ｃ．Ｉ．ダイレクトブラック１７、Ｃ．Ｉ．ダイレクトブラック１９、Ｃ．Ｉ．ダイレクトブラック２２、Ｃ．Ｉ．ダイレクトブラック３１、Ｃ．Ｉ．ダイレクトブラック３２、Ｃ．Ｉ．ダイレクトブラック５１、Ｃ．Ｉ．ダイレクトブラック６２、Ｃ．Ｉ．ダイレクトブラック７１、Ｃ．Ｉ．ダイレクトブラック７４、Ｃ．Ｉ．ダイレクトブラック１１２、Ｃ．Ｉ．ダイレクトブラック１１３、Ｃ．Ｉ．ダイレクトブラック１５４、Ｃ．Ｉ．ダイレクトブラック１６８、Ｃ．Ｉ．アシッドブラック２、Ｃ．Ｉ．アシッドブラック４８、Ｃ．Ｉ．アシッドブラック１１０、Ｃ．Ｉ．リアクティブブラック１、Ｃ．Ｉ．リアクティブブラック８、Ｃ．Ｉ．リアクティブブラック１２、Ｃ．Ｉ．リアクティブブラック１３、Ｃ．Ｉ．フードブラック１、Ｃ．Ｉ．フードブラック２等が挙げられる。
【００４２】
（イエローインク）
イエローインクに用いられる染料としては、例えば、Ｃ．Ｉ．アシッドイエロー１１、Ｃ．Ｉ．アシッドイエロー１７、Ｃ．Ｉ．アシッドイエロー２３、Ｃ．Ｉ．アシッドイエロー２５、Ｃ．Ｉ．アシッドイエロー２９、Ｃ．Ｉ．アシッドイエロー４２、Ｃ．Ｉ．アシッドイエロー４９、Ｃ．Ｉ．アシッドイエロー６１、Ｃ．Ｉ．アシッドイエロー７１、Ｃ．Ｉ．ダイレクトイエロー１２、Ｃ．Ｉ．ダイレクトイエロー２４、Ｃ．Ｉ．ダイレクトイエロー２６、Ｃ．Ｉ．ダイレクトイエロー４４、Ｃ．Ｉ．ダイレクトイエロー８６、Ｃ．Ｉ．ダイレクトイエロー８７、Ｃ．Ｉ．ダイレクトイエロー９８、Ｃ．Ｉ．ダイレクトイエロー１００、Ｃ．Ｉ．ダイレクトイエロー１３０、Ｃ．Ｉ．ダイレクトイエロー１４２等が挙げられる。
【００４３】
（マゼンタインク）
マゼンタインクに用いられる染料としては、Ｃ．Ｉ．アシッドレッド１、Ｃ．Ｉ．アシッドレッド６、Ｃ．Ｉ．アシッドレッド８、Ｃ．Ｉ．アシッドレッド３２、Ｃ．Ｉ．アシッドレッド３５、Ｃ．Ｉ．アシッドレッド３７、Ｃ．Ｉ．アシッドレッド５１、Ｃ．Ｉ．アシッドレッド５２、Ｃ．Ｉ．アシッドレッド８０、Ｃ．Ｉ．アシッドレッド８５、Ｃ．Ｉ．アシッドレッド８７、Ｃ．Ｉ．アシッドレッド９２、Ｃ．Ｉ．アシッドレッド９４、Ｃ．Ｉ．アシッドレッド１１５、Ｃ．Ｉ．アシッドレッド２５４、Ｃ．Ｉ．アシッドレッド２８９、Ｃ．Ｉ．ダイレクトレッド１、Ｃ．Ｉ．ダイレクトレッド４、Ｃ．Ｉ．ダイレクトレッド１３、Ｃ．Ｉ．ダイレクトレッド１７、Ｃ．Ｉ．ダイレクトレッド２３、Ｃ．Ｉ．ダイレクトレッド２８、Ｃ．Ｉ．ダイレクトレッド３１、Ｃ．Ｉ．ダイレクトレッド６２、Ｃ．Ｉ．ダイレクトレッド７９、Ｃ．Ｉ．ダイレクトレッド８１、Ｃ．Ｉ．ダイレクトレッド８３、Ｃ．Ｉ．ダイレクトレッド８９、Ｃ．Ｉ．ダイレクトレッド２２７、Ｃ．Ｉ．ダイレクトレッド２４０、Ｃ．Ｉ．ダイレクトレッド２４２、Ｃ．Ｉ．ダイレクトレッド２４３等が挙げられる。
【００４４】
（シアンインク）
シアンインクに用いられる染料としては、Ｃ．Ｉ．アシッドブルー９、Ｃ．Ｉ．アシッドブルー２２、Ｃ．Ｉ．アシッドブルー４０、Ｃ．Ｉ．アシッドブルー５９、Ｃ．Ｉ．アシッドブルー９３、Ｃ．Ｉ．アシッドブルー１０２、Ｃ．Ｉ．アシッドブルー１０４、Ｃ．Ｉ．アシッドブルー１１３、Ｃ．Ｉ．アシッドブルー１１７、Ｃ．Ｉ．アシッドブルー１２０、Ｃ．Ｉ．ダイレクトブルー６、Ｃ．Ｉ．ダイレクトブルー２２、Ｃ．Ｉ．ダイレクトブルー２５、Ｃ．Ｉ．ダイレクトブルー７１、Ｃ．Ｉ．ダイレクトブルー７８、Ｃ．Ｉ．ダイレクトブルー８６、Ｃ．Ｉ．ダイレクトブルー１０６、Ｃ．Ｉ．ダイレクトブルー１９９等が挙げられる。
【００４５】
又、本発明のインク中に含まれる染料としては、分子内に−ＣＯＯＭ基（Ｍはアルカリ金属、アンモニウム又は有機アンモニウムを表す。）を１個以上もつ染料が好適に使用される。具体的には、例えば、下記の一般式〔ＩＩ］〜〔Ｖ］で表される様な染料が本発明において有効に使用される。
【００４６】
【外２】

〔式中、Ａ及びＢは水酸基若しくは水素原子を、Ｃは水素原子若しくはＳＯ_３Ｍを、ＤはＳＯ_３Ｍをそれぞれ表す。］
【００４７】
【外３】

〔式中、ＣｕＰｃは銅フタロシアニン骨格を表す。Ｇは下記構造式（１）〜（４）で示される何れかを表し、
【００４８】
【外４】

ＺはＮＨＣＨ_２ＣＨ_２ＯＨ、 Ｎ（ＣＨ_２ＣＨ_２ＯＨ）_２等を表し、また上記構造式（３）においてＲ及びＲ’はＨ又は低級アルキル基等を表す。］
【００４９】
【外５】

〔式中、Ｊは下記構造式（５）〜（７）で示される何れかを表し、
【００５０】
【外６】

Ｌは下記構造式（８）または（９）を表し、
【００５１】
【外７】

Ｘは下記構造式（１０）〜（１２）の何れかを表し、
【００５２】
【外８】

Ｒ^１〜Ｒ^４は−Ｈ、低級アルキル基等を表し、上記構造式（５）〜（１２）中、Ｂは−Ｈ又は−ＣＯＯＨを、Ｗは−Ｈ、−ＣＮ、アミド基、ピリジニウム基又は−ＣＯＯＨを、ｍは２〜８の数を、Ｚはアルコキシ基、−ＯＨ、アルキルアミノ基又は−ＮＨ_２他を、Ｙは−Ｈ、−Ｃｌ又は−ＣＮを、Ｅは−Ｃｌ又は−ＣＮを、Ｒ^５は−Ｈ、低級アルキル基等を表す。］
【００５３】
【外９】

〔式中、Ｊは下記構造式（１３）を表し、
【００５４】
【外１０】

Ｌは下記構造式（１４）又は（１５）を表し、
【００５５】
【外１１】

Ｘは下記構造式（１６）〜（１８）で示される何れかを表し、
【００５６】
【外１２】

Ｒ_１及びＲ_２は−Ｈ又は低級アルキル基等を表し、上記構造式（１６）〜（１８）中、Ｚはアルコキシ基、−ＯＨ、アルキルアミノ基又は−ＮＨ_２等を、Ｙは−Ｈ、−Ｃｌ又は−ＣＮを、Ｅは−Ｃｌ又は−ＣＮを表す。］
【００５７】
（上記色材とインクｐＨの関係）
上記した色材、特に分子内に−ＣＯＯＭを含む水溶性色材をインク中に含有させる場合には、インクのｐＨを８〜１２、特には９〜１１程度に調整することが好ましい。即ちインクｐＨをこの範囲とすることで色材の水性媒体の溶解性が一段と向上し、インクの保存時の特性変化を抑制することができる。またインクのｐＨを上記範囲内とすることで、発熱ヒータ上へのコゲの発生が極めて強力に抑制される。本発明者らは、水溶性の色材とＢＨＥＳとを含むインクのｐＨを上記範囲内とした場合、発熱ヒータ上へのコゲの発生が極めて有効に抑えられるとの知見を得ており、ジカルボン酸、ジカルボン酸の塩、トリカルボン酸及びトリカルボン酸の塩の少なくとも一つの化合物のインクへの添加とインクのｐＨの調整との相乗的な効果によって発熱ヒータ上へのコゲ発生の強力な抑制効果が達成されるものである。更にまたｐＨを上記範囲内とする調整を行なった場合には、インク中にでカルボン酸の解離が進む為、インク中のカルボン酸、ジカルボン酸の塩、トリカルボン酸及びトリカルボン酸の塩の含有量は上記した範囲内で少な目としても十分な効果を得ることができる。
【００５８】
（含金染料）
また近年、布帛の染色にインクジェット記録技術を適用する提案がなされている。そして本発明者らのこれまでの研究の結果として、布帛の染色に用いるインクに含有させる水溶性の色材としては、布帛への付着性や布帛に求められる強い耐光性を考慮した場合、クロムやコバルトなどを分子内にもった含金染料が好適に用い得るとの知見を得ている。また本発明者らはこれらの色材についての更なる検討の結果、分子内の金属イオンがインク中にて遊離し発熱ヒ−タ−上にコゲを形成し易く、係るインクを用いて安定したインク吐出性能を確保する為には極めてデリケートなインクの調製が必要であるとの知見も得ている。しかし本実施態様にかかる発明によれば、かかる色材を採用したインクであっても発熱ヒータ上へのコゲの発生を有効に抑え、吐出安定性を向上させることができる。また従来インクジェット記録用のインクに用いる色材として、その使用が限定的になされている色材の適用範囲を大幅に広げることが可能となる。
【００５９】
ここで本実施態様にかかるインクの色材として用い得る含金染料の具体例としては、例えば下記の色材を挙げることができる。
【００６０】
ＣＩアシッドイエロー ５９， １２１， １５１， １５８， １９４， ２０４， ２０７， ２３２， ２３５， ２４１
【００６１】
ＣＩアシッドオレンジ １４２， １４４， １６６， １６８
【００６２】
ＣＩアシッドレッド ２１５， ２９６， ３１５， ３５７， ３５９， ３６２， ３９９
【００６３】
ＣＩアシッドバイオレット ９０（下記構造式（ＶＩ）参照）， ９２（下記構造式（ＶＩＩ）参照）， １２１，
【００６４】
【外１３】

【００６５】
【外１４】

【００６６】
ＣＩアシッドブルー １６７， １９３（下記構造式参照）， ２２９， ２８４， ２９６， ３００， ３３５， ３３８， ３４２
【００６７】
【外１５】

【００６８】
ＣＩアシッドブラウン １９， ２８２， ２８３， ２８９， ２９８， ３５５， ３５７， ３６５， ４１３， ４１５
【００６９】
ＣＩアシッドブラック ５２， ５２：１（下記構造式ＩＸ参照）， ６０， ９９，
１０７， １５５， １８８， １９４， ２２２
【００７０】
【外１６】

【００７１】
ＣＩアシッドグリーン ７３， １０４， １０８
【００７２】
（含金染料とインクｐＨについて）
本実施態様にかかるインク中の色材として上記した様な含金染料を用いた場合、インクのｐＨを３．５〜７．５、特には３．５〜６．５に調整することが好ましい。即ちインクのｐＨをこの範囲内とすることによってインク中における染料のイオン解離を抑えることができ、発熱ヒータ上へのコゲの発生をより抑制することが可能である。また本実施態様にかかるインクに用い得る色材の他の例として、例えば染料構造自体が耐熱性に劣り、コゲ等の発生のし易さの為に熱エネルギーを用いたインクジェット記録にはその使用が限定されていた様な染料もまた使用することができる。この様な色材の具体例としては例えばＣＩアシッドイエロー７９が挙げられる。
【００７３】
（水溶性有機溶媒の具体例）
次に本実施態様にかかるインクの水性媒体に含有させても良い水溶性有機溶媒としては、例えば、メタノール、エタノール、イソプロピルアルコール等の１価アルコール類、アセトン、ジアセトンアルコールなどのケトン又はケトアルコール類；テトラヒドロフラン、ジオキサン等のエーテル類；ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、ジプロピレングリコール、トリプロピレングリコール、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オキシエチレン又はオキシプロピレン付加重合体；エチレングリコール、プロピレングリコール、トリメチレングリコール、ブチレングリコール、ヘキシ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；１，２，６−ヘキサントリオール等のトリオール類；チオジグリコール；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；トリエチレングリコールジメチル（又はエチル）エーテル、テトラエチレングリコールジメチル（又はエチル）エーテル等の多価アルコールの低級ジアルキルエーテル類等が挙げられる。上記水溶性有機溶剤の含有量は、一般的にはインクの全重量に対して重量％で０〜４０％、好ましくは２〜３０％の範囲である。上記のごとき媒体を併用する場合は単独でも混合物としても使用できるが、好ましい水溶性有機溶剤は、１価アルコール類、ケトン類、グリセリン、エチレングリコール、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、チオジグリコール、プロピレングリコール、ジプロピレングリコール、トリプロピレングリコール及びその誘導体（中でもそのアルキルエーテル類）である。
【００７４】
（他の成分）
また本実施態様に係るインクには、このインクが奏する効果を損なわない範囲内でその他各種の消泡剤、粘度調整剤、表面張力調整剤、ｐＨ調整剤等を必要に応じて添加しても良い。
【００７５】
（第２の実施態様／尿素の添加）
本発明の第２の実施態様にかかるインクとして、上記の実施態様に係るインクに対して更に尿素を含有させたインクを挙げられる。この第２の実施態様に係るインクによれば、第１の実施態様に係るインクによって奏される効果に加え、従来と比してより改善された再吐出性をインクに付与することができる。ここで再吐出性とは記録を一時停止した後に再度オリフィスからインクを吐出させる動作をいう。本発明者らはこれまでの検討から水溶性の色材を含む水溶性インクの中には、記録を一時中止している最中にオリフィスに臨むインクが固化してオリフィスを完全に、或いは部分的に塞いでしまい、インクの再吐出が不可能となったり、所定の量のインクを正確な方向に吐出させることが不可能となったりすることがあり、この傾向は特に記録画像の高精細化に伴うオリフィスの微細化した場合やインクジェット記録装置の普及に伴う使用条件の多様化、特に低温環境下でのインクジェット記録装置の使用した場合に多く見られるとの知見を得ている。しかし本実施態様に係るインクに更に尿素の含有させることで、第１の実施態様に係るインクによって奏される効果に加え、上記した様な条件下でも再吐出性を安定化させることができるという効果もまた得られるものである。
【００７６】
ところでこのような構成を採用することによって上記の効果を奏する理由は明らかでないが、インク中のＢＨＥＳは常温では固体であり、水性媒体に占める割合が２０ｗｔ％を越えるとワックス状に析出し易くなる性質を有するため、オリフィスに臨むインクにおいてもミクロ的にみるとオリフィスからの水の蒸発に伴ってこの現象が始まるものと考えられる。一方尿素は水と水溶性染料との親和性を非常に高めるため、ＢＨＥＳと尿素とを共存させることで、オリフィスに臨むインクではＢＨＥＳの析出によるオリフィスからのインク中の水分の蒸発抑制効果と、オリフィス近傍のインクの染料濃度の急激な上昇を抑える効果との相乗効果によっているものと考えられる。この態様に於いて尿素の量は、インク全重量に対して０．１〜２０重量％、特には０．１〜１５重量％とすることが好ましく、またインク全重量に対する尿素とＢＨＥＳの合計の量は、０．２〜３０重量％、特には０．６〜２５重量％とすることが好ましい。
【００７７】
（装置）
次に上記したインクを用いることのできるインクジェット記録装置及びそれを用いた画像記録方法について説明する。
【００７８】
（ヘッド構成）
図１は、熱エネルギーを利用してインクを吐出させる方式のインクジェット記録装置の主要部の一つを構成するヘッドの一実施態様の、インクが吐出されるオリフィス部分を縦に横切る方向の概略断面図である。また図２は図１のＡＡ線断面図である。図１及び図２において、ヘッド１３はインクを通す溝１４を有するガラス、セラミックスまた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、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よい基板２０よりなっている。インク２１は吐出オリフィス（微細孔）２２まで来ており、所定の圧力Ｐによりメニスカス２３を形成している。そして電極１７−１、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、オリフィス２２よりインク２１が吐出し、被記録媒体（例えば紙など）２５に向かって飛翔し、被記録媒体２５の画像記録領域に付着して画像が記録される。
【００７９】
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。
【００８０】
上記したヘッドの構成において、オリフィスのサイズは特に限定されず、所望の画像品質に応じて適宜設定すれば良い。しかし近年の高画質化への要求に伴い、オリフィスのサイズを微細化することが検討されている。具体的には例えば１回の吐出動作によってオリフィスから吐出されるインクの量が０．１〜４０ピコリットル（ｐｌ）、特には０．１〜３０ｐｌとなるようなオリフィスの微細化が検討されており、このようなサイズのオリフィスにおいては、記録一時停止後にインクを安定して再吐出させることが高品質な画像を形成する上で特に好ましい技術目標の一つとなる。そして上記した 本発明の種々の実施態様にかかるインク、特に第２の実施態様にかかるインクはこの技術目標を克服することのできる極めて有効な技術の一つに挙げることができるものである。
【００８１】
またオリフィスが上記した様に微細化されていない場合であっても、インクジェット記録装置の普及に伴う使用環境の多様化、具体的には例えば周囲温度が５℃以下の環境（例えば寒冷地で暖房の効かない室内や屋外）下でのインクジェット記録装置の使用の際には前記した様にオリフィスの目詰まりによるインク不吐出が生じることがあり、インクジェット記録装置のより一層の普及という観点からこの点も克服すべき重要な技術目標の一つに挙げられる。そして上記の各実施態様にかかるインク、特には第２の実施態様にかかるインクはこの技術目標を克服することができる極めて有効な技術の一つに挙げることができる。
【００８２】
（インクジェット記録装置）
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一例を示す。図４において、６１はワイピング部材としてのブレードであり、その一端はブレード保持部材によって保持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、本例の場合、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に水分、塵埃等の除去が行われる。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布帛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の移動を行う為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は記録紙を挿入する為の給紙部、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記録紙が給紙され記録が進行するにつれて排布ローラ５３を配した排紙部へ排紙される。
【００８３】
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に突出する様に移動する。
【００８４】
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。
【００８５】
（インクカートリッジ）
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に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。
【００８６】
（記録ユニット）
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為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。
【００８７】
（インクセット）
ところで上記した種々の実施態様にかかるインクは、色材の選択によって例えばイエロー、マゼンタ、シアン、レッド、グリーン、ブルーまたはブラックのインクとすることができる。そして各々のインクは各々単独で画像記録に用いてもよい。または２つ以上の異なる色のインクとを組合わせて、カラー画像の形成に好適に用い得るインクセットを提供することができる。また同じ色の、異なる色材を含む２つもしくはそれ以上のインクを組合わせたり、同じ色の、濃度の異なる２つもしくはそれ以上のインクを組合わせることによって高階調の画像の形成に好適に用い得るインクセットを提供することができる。またこれらのインクセットを用いて画像を形成する場合には、例えば前記図３に示した記録ヘッドを４つキヤリッジ上に並べた記録装置を用いることができる。図８はその一実施例であり、８６、８７、８８及び８９は各々例えばイエロー、マゼンタ、シアン及びブラックのインクを吐出するための記録ヘッドである。該記録ヘッドは前記した記録装置に配置され、記録信号に応じて各色のインクを吐出する。また図８では記録ヘッドを４つ使用した例を示したが、これに限定されず例えば図７に示した様に上記４色のインクカートリッジを用いて１つのヘッドでインク流路を分けてカラー画像記録を行なう実施態様も挙げられる。
【００８８】
なおここまで記録信号に対応した熱エネルギーをインクに与え、該熱エネルギーよりにインクを吐出させる装置及びそれを用いた画像記録方法に本発明にかかるインクを用いた場合を説明してきた。しかし本発明のインクは機械エネルギーによってインクを吐出させる方式のインクジェット記録装置及びそれを用いた画像記録方法にも用いることができ、それによって同様の優れた効果を得ることができる。
【００８９】
【実施例】
（実施例１〜１４）
下記表１に示した組成のインクを各々調製した。即ち各々の材料を混合し、２時間攪拌した後、４規定−水酸化リチウム（ＬｉＯＨ）で所望のｐＨに調整し、次いで孔径０．２μｍのメンブレンフィルターで加圧濾過して各々の記録インクを得た。尚下記表中ＦＢ２は、Ｃ．Ｉ．フードブラック２、ＤＹ８６はＣ．Ｉ．ダイレクトイエロー８６の略である。
【００９０】
また化合物１は前記構造式（Ｖ）中、「Ｌ」が前記構造式（１５）、「Ｘ」が前記構造式（１６）、「Ｒ１」及び「Ｒ２」が水素原子、−ＮＨ２で示される構造の色素である。
【００９１】
【表１】

【００９２】
（参考例１〜３）
下記表２に示す組成のインクを実施例にて調製したインクと同様の方法で調製した。
【００９３】
【表２】

【００９４】
上記実施例１〜１４及び参考例１〜３のインクについて、一回の吐出動作によって１ノズルから吐出されるインク量が２０ｐｌとなるように構成されたインクジェット記録用ヘッドを用いて６×１０８発吐出させ、その後に下記の項目についての評価を行なった。その結果を下記表３に示す。
【００９５】
〔評価項目］
（１）液滴サイズ（吐出量変化）
６×１０^８発吐出後の１ノズルあたりのインク吐出量を測定し、そのノズルの初期のインク吐出量と比較した。
○：初期と比較して、吐出試験後のインク吐出量が９５％以上。
△：初期と比較して、吐出試験後のインク吐出量が８０％以上９５％未満。
×：初期と比較して、吐出試験後のインク吐出量が８０％未満。
【００９６】
（２）ヒータ面観察
６×１０^８発吐出後のヘッドを分解し、そのヒータ面を光学顕微鏡で観察した。
◎：コゲは殆ど観察されない。
○：多少コゲが観察されるが、吐出に影響を与えないレベルである。
△：コゲが多く観察される。
【００９７】
（３）画像の劣化（着弾精度）
６×１０^８発吐出後、コート紙（商品名：ＨＲ１０１；キヤノン（株）社製）上に６００ｄｐｉの解像度の直線を記録し、各ドットの位置関係（着弾位置）をビデオ画像に取込んで、６００ｄｐｉの格子点からのずれ量（±μｍ）を測定した。
○：着弾精度が±１０μｍ未満である。
△：着弾精度が±１０μｍ以上１５μｍ未満である。
×：着弾精度が±１５μｍ以上である。
【００９８】
【表３】

【００９９】
上記表３の結果から、一回の吐出動作によって１ノズルから吐出されるインク量が少なく構成されているインクジェット記録用ヘッドを用いて、例えば６×１０８発吐出させるといった過酷な記録を行なった後にも発熱ヒータ面上へのコゲの発生が有効に抑制されたことが分かった。
【０１００】
また実施例１〜３、１２と参考例１の結果、実施例４〜５、１３と参考例２の結果から、ビスヒドロキシエチルスルホンとジカルボン酸、その塩、トリカルボン酸及びその塩から選ばれる少なくとも１つとの併用によって吐出量変化、コゲ性、及び着弾精度の３つをより一層改良できた。特にビスヒドロキシエチルスルホンとクエン酸の併用によってヒータ面へのコゲの発生の更なる抑制を図ることができた。
【０１０１】
（実施例１５〜２０）
上記実施例６〜１１の組成と同じ組成のインクを調製し、実施例１５〜２０のインクとした。各々のインクを用いて、発熱ヒータによてインクに熱エネルギーを付与することでインクを吐出させる方式のインクジェットプリンタ（商品名：ＢＪ１３０；キヤノン（株）社製）を使用して市販のコピー用紙に駆動周波数２ｋＨｚで記録を行ない、記録一時停止後に再度吐出動作を行なわせたときのインクの再吐出性について評価した。なおここで用いたプリンタのヘッドとしては、１回の吐出動作によって１ノズルから吐出されるインク量が約６０ｐｌとなるように構成されているものを用いた。また評価条件は、上記の各々のインクを上記プリンタを用いて、室温０℃、湿度２５±５％の環境下で１分間連続して英数文字を印字した後、３０秒間印字を停止し、再度英数文字を印字したときの文字のかすれ、欠け等の印字不良箇所を観察した。このときヘッド温度は３５±５℃であった。その結果を下記表４に示す。なお評価基準は以下の通りである。
○：再記録時の１文字目からかすれや欠けは認められない。
△：再記録時の１文字目の一部がかすれ、または欠けが認められる。
×：再記録時の１文字目が全く印字できない。
【０１０２】
【表４】

【０１０３】
（実施例２１〜２４）
下記表５に示した組成のインクを上記実施例１〜１４のインクと同様の方法で調製した。
【０１０４】
【表５】

【０１０５】
（参考例４〜６）
下記表６に示した組成のインクを上記実施例１〜１４のインクと同様の方法で調製した。
【０１０６】
【表６】

【０１０７】
上記実施例２１〜２４及び参考例４〜６のインクについてバブルジェットカードプリンタ（商品名：Ｐ−４００ＣＩＩ；キヤノン（株）社製）用のヘッドを用いてコゲ性、吐出安定性及びヒータ断線の有無を評価した。このときに用いた記録ヘッドは１ノズルあたり１回の吐出動作で約５０ｐｌのインクを吐出する。この結果を下記表７に示す。なお評価基準は以下の通りである。
【０１０８】
（１）コゲ性
１０本のノズルで２×１０８パルスの連続印字を行なった後、ヘッドを分解しヒータ面を光学顕微鏡にて観察したときに、ヒータ面のコゲを下記の基準で評価した。
○：ヒータ面のコゲが全く観察されない。
△：コゲがヒータの縁に多少観察される。
×：ヒータ全面にコゲが観察される。
【０１０９】
（２）吐出安定性
１０本のノズルで２×１０８パルスの連続印字を行なったときに、吐出液量や吐出速度の減少等を測定し、下記の基準で評価した。
○：吐出量低下が全く起きない。
△：初期の吐出量に対し、耐久後の吐出量が１０％以上５０％未満の低下した。
×：初期の吐出量に対し、耐久後の吐出量が５０％以上低下し、或いは吐出不能となった。
【０１１０】
（３）ヒータの断線
１６本のノズルで５×１０７パルスの連続印字を行なったときに、ヒータの断線の程度を下記の基準で評価した。
○：断線が観察されなかった。
×：１本以上のノズルで断線が観察された。
【０１１１】
【表７】

【０１１２】
【発明の効果】
以上説明したように本発明の実施態様によれば、
長時間の記録によっても発熱ヒータ上へのコゲの発生が有効に防止でき、吐出安定性を向上させることができる。また吐出安定性の向上によって、高品質な画像の記録を安定して行なうことができる。
【０１１３】
また発熱ヒータ上へのコゲの発生を有効に防止でき、吐出安定性を向上させられると共に、記録一時停止後のインクの再吐出性についても改善することができる。
【０１１４】
更に多様な被記録媒体に対して高い品質の画像を安定して記録することができ、多様な使用環境下でも安定して高品位な画像を形成することができる。また記録画像のより一層の高品質化の為にオリフィスを微細化によって高画質化を図った場合にも、発熱ヒータ上へのコゲが抑制され、またインクの再吐出性も改善され、高精細な画像を安定して記録することができる。
【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の一実施態様を示す縦断面図である。
【図２】図１のＡＡ線断面図である。
【図３】マルチヘッドの概略説明図である。
【図４】インクジェット記録装置の一実施態様を示す概略斜視図である。
【図５】インクカートリッジの一実施態様を示す縦断面図である。
【図６】インクジェット記録ヘッドの別の構例を示す概略斜視図である。
【図７】４つのインクカートリッジが取り付けられた記録ヘッドの概略説明図である。
【図８】４つの記録ヘッドがキャリッジ上に並べられている構成を示す概略説明図である。
【符号の説明】
１３ ヘッド
１４ インク溝
１５ 発熱ヘッド
１６ 保護膜
１７−１、１７−２ 電極
１８ 発熱抵抗体槽
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 インク滴
２５ 被記録材
２６ マルチ溝
２７ ガラス板
４０ インク袋
４２ 栓
４４ インク吸収体
４５ インクカートリッジ
５１ 給紙部
５２ 紙送りローラー
５３ 排紙ローラー
６１ ブレード
６２ キヤップ
６３ インク吸収体
６４ 吐出回復部
６５ 記録ヘッド
６６ キヤリッジ
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
８０ インク流路
８１ オリフィスプレート
８２ 振動板
８３ 圧電素子
８４ 基板
８５ 吐出口
８６、８７、８８、８９ 記録ヘッド[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink that can be suitably used for ink-jet recording, in which an ink, particularly an ink is ejected from an orifice according to a recording signal to perform recording on a recording medium, an ink set using the ink, an ink cartridge, a recording unit, and an image recording apparatus And an image recording method.
[0002]
[Prior art]
Various methods have been proposed for the ink jet recording technology so far, for example, a method of continuously generating charged ink droplets and using a part of the ink droplets for recording, a recording head having a piezoelectric element. A method in which a signal is applied and ink is ejected in accordance with the signal to perform printing, or thermal energy corresponding to a print signal is applied to ink in a print head chamber using, for example, a heating heater, and the energy is applied. There is a method of ejecting ink to perform recording. For example, as described in Japanese Patent Application Laid-Open No. 54-59936, an ink jet recording method in which ink is ejected by utilizing the bubbling phenomenon of ink due to thermal energy is used for an opening (hereinafter referred to as an "orifice") through which ink is ejected. This method is one of the mainstays of the current ink jet recording method because it is easy to achieve high integration and high density.
[0003]
On the other hand, with respect to inks used for these ink jet recording techniques, those having various compositions have been reported and proposed for the purpose of, for example, obtaining images of superior quality. In particular, in recent years, in order to perform good recording on plain paper generally used in offices such as copy paper, report paper, notes, stationery, etc., and even on cloth, the ink composition and ink physical properties, etc. Detailed research and development has been made from various aspects of
[0004]
By the way, for example, it is preferable that the ink used in the ink jet recording technique of a method of performing recording by applying heat energy corresponding to a recording signal to the ink using a heating heater and discharging the ink from an orifice by the energy is used. One of the characteristics is that, for example, there is no or little foreign matter (hereinafter referred to as “koge”) deposited on the heating heater during printing. That is, in the ink jet recording technology of a method of discharging ink using thermal energy, foreign substances gradually deposit on the surface of the heating head, and as a result, thermal conductivity to the ink decreases, and bubbles necessary for discharging are sufficiently reduced. In some cases, a phenomenon occurs in which the ink is not ejected and the amount of ink required for normal recording is not ejected, or the ink is not ejected at all. That is, the ejection stability of the ink is reduced.
[0005]
To cope with such technical problems, conventionally, for example, JP-A-3-160070 discloses an attempt to improve the kogation generation by including an oxo anion in the ink. Japanese Patent Application Laid-Open No. 7-334361 discloses a technique for suppressing the occurrence of kogation by including phytic acid and / or a salt thereof in an ink. Japanese Patent Application Laid-Open No. 8-80664 discloses a technique in which a liquid composition containing a cationic substance and bishydroxyethyl sulfone (BHES) are used in combination to prevent kogation on a heating head and improve ejection durability. Have been.
[0006]
[Problems to be solved by the invention]
The present inventors have studied in detail the problem of kogation particularly with respect to an aqueous ink containing a water-soluble coloring material as a coloring material. As a result, although the kogation is significantly improved by the addition of BHES, the recording time is prolonged. It has been found that a kogation different from the conventional one may occur on the heating heater. When the kogation was examined, it was found that it contained sulfur, carbon, and inorganic metals such as calcium and iron. Although sulfur atoms may exist as sulfonic acid groups in the water-soluble coloring material, the generation of kogation containing sulfur atoms was hardly observed on the heating heater when BHES was not used. Therefore, it was presumed that the cause of this kogation was derived from BHES. This kogation is slightly smaller than the kogation generated on the heating heater by the ink to which BHES is not added. Is configured such that the amount of ink ejected from the orifice in a single ejection operation is smaller than in the past, the amount of energy given to the ink by the heating heater is small, so that a fine kogation Even if ink adheres, it may cause a change in the ink ejection amount that affects the printing of high-definition images, and technical development to solve this problem is required to stably obtain high-quality images. We came to the conclusion that it was necessary.
[0007]
As a result of further studies on such a new technical problem, the present inventors have found that a dicarboxylic acid, a salt of a dicarboxylic acid, a tricarboxylic acid and a tricarboxylic acid are contained in an aqueous ink containing a water-soluble coloring material and BHES. It has been found that by adding at least one substance selected from the group consisting of the following, the generation of kogation can be extremely effectively suppressed even when the recording time is long.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to provide an ink which does not affect the heating heater in such a manner as to change the ink ejection performance when used for long-time ink jet recording by a method of discharging ink using the heating heater. It is in.
[0009]
Another object of the present invention is to provide an image recording method capable of stably recording an image of excellent quality even when recording for a long time.
[0010]
Another object of the present invention is to provide an image recording apparatus capable of stably recording an image of excellent quality even when recording for a long time, an ink cartridge, an ink set, and a recording unit that can be used therein. It is in.
[0011]
Further, an object of the present invention is to reduce the influence of changing the ink discharge performance on the heat generating heater when using it for a long-time ink jet recording by a method of discharging ink using the heat generating heater, and for various purposes. It is an object of the present invention to provide an ink in which non-discharge from an orifice after a temporary suspension of recording hardly occurs even in a use environment or when the orifice is further miniaturized.
[0012]
Further, an object of the present invention is to stably record an image of excellent quality even by long-time recording, and to form a high-quality image stably even in various use environments, or to improve the quality of a recorded image. It is an object of the present invention to provide an image recording method capable of stably exhibiting the effect even when the orifice is miniaturized for further improving the quality.
[0013]
Furthermore, an object of the present invention is to stably form an image of excellent quality even after long-time recording, and to stably form a high-quality image even in various use environments. Provided is an image recording apparatus capable of stably exerting its effect even when an orifice is miniaturized for further improving the quality of an image, and an ink cartridge, an ink set, and a recording unit that can be used in the image recording apparatus. It is in.
[0014]
[Means for Solving the Problems]
The ink according to an embodiment of the present invention that can achieve the above object includes at least one substance selected from dicarboxylic acids, salts of dicarboxylic acids, tricarboxylic acids and salts of tricarboxylic acids, bishydroxyethyl sulfone, and water-soluble. Characterized in that an aqueous coloring material is contained in the aqueous medium.
[0016]
In addition, the ink cartridge according to an embodiment of the present invention that can achieve the above object includes dicarboxylic acid, at least one substance selected from dicarboxylic acid salts, tricarboxylic acid and tricarboxylic acid salts, bishydroxyethyl sulfone, And an ink storage unit that stores ink containing a water-soluble coloring material in an aqueous medium.
[0018]
Further, a recording unit as one embodiment of the present invention capable of achieving the above object, is a dicarboxylic acid, a salt of a dicarboxylic acid, at least one substance selected from a salt of a tricarboxylic acid and a salt of a tricarboxylic acid, bishydroxyethyl sulfone, And an ink storage unit storing an ink containing a water-soluble coloring material in an aqueous medium, a unit for applying the recording ink to the recording medium, and a unit for supplying the ink to the unit. It is characterized by.
[0020]
In addition, the ink set as one embodiment of the present invention that can achieve the above object, dicarboxylic acid, dicarboxylic acid salt, tricarboxylic acid and at least one substance selected from tricarboxylic acid salt, bishydroxyethyl sulfone, And an ink containing a water-soluble first coloring material in an aqueous medium and an ink containing a second coloring material, wherein the first and second coloring materials are each for yellow. , Magenta, cyan, black, red, blue, and green.
[0021]
The image recording method as one embodiment of the present invention that can achieve the above object is a dicarboxylic acid, a salt of a dicarboxylic acid, at least one substance selected from tricarboxylic acids and salts of tricarboxylic acids, bishydroxyethyl sulfone, And a step of applying an ink containing a water-soluble coloring material in an aqueous medium to an image forming area of the recording medium.
[0023]
The image recording apparatus as one embodiment of the present invention capable of achieving the above object is a dicarboxylic acid, a salt of a dicarboxylic acid, at least one substance selected from a salt of a tricarboxylic acid and a salt of a tricarboxylic acid, bishydroxyethyl sulfone, And an ink storage unit that stores ink containing a water-soluble coloring material in an aqueous medium, a unit that applies the ink to a recording medium, and a unit that supplies the ink to the unit. And a unit for activating the unit and a unit for applying the recording ink to the recording medium in response to the recording signal.
[0025]
According to each of the above-described embodiments, even when ink is discharged for a long time, the change in ink discharge performance is small, and an image of excellent quality can be stably recorded for a long time.
[0026]
The image recording method as one embodiment of the present invention capable of achieving the above object includes a dicarboxylic acid, a salt of a dicarboxylic acid, at least one substance selected from a tricarboxylic acid and a salt of a tricarboxylic acid, bishydroxyethyl sulfone, An ink containing urea and a water-soluble coloring material in an aqueous medium, wherein the total amount of the dicarboxylic acid, dicarboxylic acid salt, tricarboxylic acid and tricarboxylic acid salt is 0.7% or less based on the total weight of the ink. A recording head having means for ejecting the recording ink from an orifice to a recording medium, and a means for supplying the recording head with the ink. A recording unit configured to be able to eject 0.1 to 40 picoliters of ink from the orifice in operation; Using an image recording device and means for actuating the recording unit characterized by having a step of attaching to the image recording region of the recording medium the ink.
[0027]
The image recording apparatus as one embodiment of the present invention capable of achieving the above object is a dicarboxylic acid, a salt of a dicarboxylic acid, at least one substance selected from a salt of a tricarboxylic acid and a salt of a tricarboxylic acid, bishydroxyethyl sulfone, Contains an ink containing urea and a water-soluble coloring material in an aqueous medium, wherein the total amount of the dicarboxylic acid, dicarboxylic acid salt, tricarboxylic acid and tricarboxylic acid salt is 0.7% or less based on the total weight of the ink. A recording head having means for discharging the recording ink from an orifice to a recording medium, and a means for supplying the recording head with the ink, wherein the recording head is provided once. A recording unit configured to be able to eject 0.1 to 40 picoliters of ink from an orifice in an ejection operation, and according to a recording signal. Characterized in that it comprises a means for actuating the recording unit.
[0028]
The recording unit according to an embodiment of the present invention that can achieve the above object includes at least one substance selected from dicarboxylic acids, salts of dicarboxylic acids, tricarboxylic acids and salts of tricarboxylic acids, bishydroxyethyl sulfone, and urea. And an ink containing a water-soluble coloring material in an aqueous medium, wherein the total amount of the dicarboxylic acid, dicarboxylic acid salt, tricarboxylic acid and tricarboxylic acid salt is 0.7% or less based on the total weight of the ink. A recording head having means for ejecting the recording ink from an orifice to a recording medium, and a means for supplying the recording head with the ink. It is characterized in that 0.1 to 40 picoliters of ink can be ejected from the orifice in operation.
[0029]
According to each of the above-described embodiments, and according to each of the above-described embodiments, there is little change in ink ejection performance even after long-time ink ejection, and further, in various use environments, or an orifice is further miniaturized. Even in such a case, clogging of the orifice after the recording is temporarily stopped is unlikely to occur, and an even higher quality image can be recorded extremely stably.
Furthermore, the method for reducing kogation adherence according to one aspect of the present invention is a method for applying kogation to ink using an exothermic heater and ejecting the ink from an orifice using the energy. A reduction method, wherein the ink for ink jet described above is used as the ink.
[0030]
(Action)
By the way, with respect to each embodiment of the present invention described above, the aqueous ink containing a water-soluble coloring material and BHES in the aqueous ink contains at least one selected from dicarboxylic acids, salts of dicarboxylic acids, tricarboxylic acids, and salts of tricarboxylic acids. It is not clear why the inclusion stability increases the ejection stability of the ink. However, the nature of the kogation formed on the heater changes due to the addition of these substances, and the kogation is temporarily deposited on the heating heater. Also, it is considered that the generation of kogation on the heat generating heater is suppressed to a very low level because the adhesiveness to the heat generating heater is weak.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described in more detail by way of preferred embodiments.
[0032]
(First embodiment)
The ink according to the first embodiment of the present invention contains, in an aqueous medium, at least one substance selected from dicarboxylic acids, salts of dicarboxylic acids, tricarboxylic acids and salts of tricarboxylic acids, BHES, and a water-soluble coloring material. It is a thing.
[0033]
(BHES / amount)
BHES has a structure represented by the following structural formula (I), and a commercially available product synthesized by a conventionally known method can be used.
[0034]
[Outside 1]

[0035]
The content of BHES in the ink is, for example, preferably 0.1 to 30% by weight, particularly preferably 1 to 20% by weight based on the total weight of the ink. With such a range, it is possible to more effectively suppress kogation on the heating heater, for example, kogation derived from the coloring material in the ink.
[0036]
(Dicarboxylic acid, salt of dicarboxylic acid, tricarboxylic acid and salt of tricarboxylic acid)
Specific examples of dicarboxylic acids, salts of dicarboxylic acids, tricarboxylic acids and salts of tricarboxylic acids will be described below. Specific examples of the dicarboxylic acid include, for example, succinic acid, maleic acid and phthalic acid. Specific examples of the tricarboxylic acid include, for example, citric acid. Further, examples of salts of these dicarboxylic acids and tricarboxylic acids include salts of metals such as sodium. In particular, when at least one of citric acid and sodium citrate is contained in an ink containing BHES and a water-soluble coloring material, generation of kogation on the heating heater is strongly suppressed, and under normal recording conditions. In this case, the heating heater is not disconnected, and can be used extremely favorably for further improving the ejection stability.
[0037]
The content of such a substance in the ink is preferably 0.0001 to 0.7% by weight, particularly 0.002 to 0.5% by weight based on the total weight of the ink. By setting it within this range, more excellent ejection stability can be obtained.
[0038]
(Coloring material / content)
The coloring material is not particularly limited as long as it is water-soluble.For example, a conventionally known water-soluble dye, for example, a water-soluble anionic dye, a direct dye, an acid dye, a reactive dye, or the like may be used. it can. The content of the dye in the ink is preferably, for example, 0.5 to 15% by weight, particularly preferably 1 to 12% by weight based on the total weight of the ink, in consideration of the density of the recorded image and the ejection characteristics of the ink. .
[0039]
(About aqueous medium)
The aqueous medium is for holding the above-mentioned substance selected from dicarboxylic acid, dicarboxylic acid salt, tricarboxylic acid and tricarboxylic acid salt, BHES, and a water-soluble coloring material in a dissolved state to constitute an ink. . It is preferable that the aqueous medium contains at least water as a component, and a water-soluble organic solvent may be mixed to increase the solubility of various components of the ink or to adjust various characteristics of the ink. The ratio of water to the total weight of the ink is, for example, 20 to 95% by weight, preferably 40 to 95% by weight, and more preferably 60 to 95% by weight.
[0040]
(Specific examples of water-soluble dyes)
By the way, examples of the water-soluble dye containing an anionic group that can be used for the coloring material of the ink according to the present embodiment include the following.
[0041]
(Black ink)
Examples of the dye used in the black ink include C.I. I. Direct Black 17, C.I. I. Direct Black 19, C.I. I. Direct Black 22, C.I. I. Direct Black 31, C.I. I. Direct Black 32, C.I. I. Direct Black 51, C.I. I. Direct Black 62, C.I. I. Direct Black 71, C.I. I. Direct Black 74, C.I. I. Direct Black 112, C.I. I. Direct Black 113, C.I. I. Direct Black 154, C.I. I. Direct Black 168, C.I. I. Acid Black 2, C.I. I. Acid Black 48, C.I. I. Acid Black 110, C.I. I. Reactive Black 1, C.I. I. Reactive Black 8, C.I. I. Reactive black 12, C.I. I. Reactive Black 13, C.I. I. Food black 1, C.I. I. Food Black 2 and the like.
[0042]
(Yellow ink)
Examples of the dye used in the yellow ink include C.I. I. Acid Yellow 11, C.I. I. Acid Yellow 17, C.I. I. Acid Yellow 23, C.I. I. Acid Yellow 25, C.I. I. Acid Yellow 29, C.I. I. Acid Yellow 42, C.I. I. Acid Yellow 49, C.I. I. Acid Yellow 61, C.I. I. Acid Yellow 71, C.I. I. Direct Yellow 12, C.I. I. Direct Yellow 24, C.I. I. Direct Yellow 26, C.I. I. Direct Yellow 44, C.I. I. Direct Yellow 86, C.I. I. Direct Yellow 87, C.I. I. Direct Yellow 98, C.I. I. Direct Yellow 100, C.I. I. Direct Yellow 130, C.I. I. Direct Yellow 142 and the like.
[0043]
(Magenta ink)
Dyes used for magenta ink include C.I. I. Acid Red 1, C.I. I. Acid Red 6, C.I. I. Acid Red 8, C.I. I. Acid Red 32, C.I. I. Acid Red 35, C.I. I. Acid Red 37, C.I. I. Acid Red 51, C.I. I. Acid Red 52, C.I. I. Acid Red 80, C.I. I. Acid Red 85, C.I. I. Acid Red 87, C.I. I. Acid Red 92, C.I. I. Acid Red 94, C.I. I. Acid red 115, C.I. I. Acid Red 254, C.I. I. Acid Red 289, C.I. I. Direct Red 1, C.I. I. Direct Red 4, C.I. I. Direct Red 13, C.I. I. Direct Red 17, C.I. I. Direct Red 23, C.I. I. Direct Red 28, C.I. I. Direct Red 31, C.I. I. Direct Red 62, C.I. I. Direct Red 79, C.I. I. Direct Red 81, C.I. I. Direct Red 83, C.I. I. Direct Red 89, C.I. I. Direct Red 227, C.I. I. Direct Red 240, C.I. I. Direct Red 242, C.I. I. Direct Red 243 and the like.
[0044]
(Cyan ink)
Dyes used for cyan ink include C.I. I. Acid Blue 9, C.I. I. Acid Blue 22, C.I. I. Acid Blue 40, C.I. I. Acid blue 59, C.I. I. Acid Blue 93, C.I. I. Acid blue 102, C.I. I. Acid blue 104, C.I. I. Acid Blue 113, C.I. I. Acid blue 117, C.I. I. Acid blue 120, C.I. I. Direct Blue 6, C.I. I. Direct Blue 22, C.I. I. Direct Blue 25, C.I. I. Direct Blue 71, C.I. I. Direct Blue 78, C.I. I. Direct Blue 86, C.I. I. Direct Blue 106, C.I. I. Direct Blue 199 and the like.
[0045]
As the dye contained in the ink of the present invention, a dye having one or more -COOM groups (M represents an alkali metal, ammonium or organic ammonium) in a molecule is preferably used. Specifically, for example, dyes represented by the following general formulas [II] to [V] are effectively used in the present invention.
[0046]
[Outside 2]

Wherein A and B represent a hydroxyl group or a hydrogen atom, and C represents a hydrogen atom or a SO₃M for D, SO for₃M represents each. ]
[0047]
[Outside 3]

[In the formula, CuPc represents a copper phthalocyanine skeleton. G represents any of the following structural formulas (1) to (4);
[0048]
[Outside 4]

Z is NHCH₂CH₂OH, N (CH₂CH₂OH)₂And R and R 'in the above structural formula (3) represent H or a lower alkyl group. ]
[0049]
[Outside 5]

[Wherein, J represents any one of the following structural formulas (5) to (7);
[0050]
[Outside 6]

L represents the following structural formula (8) or (9);
[0051]
[Outside 7]

X represents any of the following structural formulas (10) to (12);
[0052]
[Outside 8]

R¹~ R⁴Represents -H, a lower alkyl group or the like, and in the above structural formulas (5) to (12), B represents -H or -COOH, W represents -H, -CN, an amide group, a pyridinium group or -COOH, m is a number from 2 to 8, Z is an alkoxy group, -OH, an alkylamino group or -NH₂In others, Y is -H, -Cl or -CN, E is -Cl or -CN, R⁵Represents -H, a lower alkyl group or the like. ]
[0053]
[Outside 9]

[Wherein J represents the following structural formula (13);
[0054]
[Outside 10]

L represents the following structural formula (14) or (15);
[0055]
[Outside 11]

X represents any of the following structural formulas (16) to (18);
[0056]
[Outside 12]

R₁And R₂Represents -H or a lower alkyl group; and in the above structural formulas (16) to (18), Z represents an alkoxy group, -OH, an alkylamino group, or -NH.₂Y represents -H, -Cl or -CN, and E represents -Cl or -CN. ]
[0057]
(Relationship between the above coloring material and ink pH)
When the above-mentioned coloring material, particularly a water-soluble coloring material containing -COOM in a molecule, is contained in the ink, the pH of the ink is preferably adjusted to 8 to 12, particularly 9 to 11. That is, by setting the pH of the ink within this range, the solubility of the coloring material in the aqueous medium is further improved, and the change in characteristics of the ink during storage can be suppressed. By setting the pH of the ink within the above range, the occurrence of kogation on the heating heater is extremely strongly suppressed. The present inventors have found that when the pH of an ink containing a water-soluble coloring material and BHES is within the above range, the occurrence of kogation on the heating heater is extremely effectively suppressed. The synergistic effect of adding at least one compound of an acid, a salt of a dicarboxylic acid, a tricarboxylic acid and a salt of a tricarboxylic acid to the ink and adjusting the pH of the ink has a strong effect of suppressing kogation on the heating heater. Is achieved. Furthermore, when the pH is adjusted within the above range, the dissociation of the carboxylic acid proceeds in the ink, so that the content of the carboxylic acid, the salt of the dicarboxylic acid, the salt of the tricarboxylic acid, and the salt of the tricarboxylic acid in the ink. In the above range, a sufficient effect can be obtained even with a small amount.
[0058]
(Gold-containing dye)
In recent years, proposals have been made to apply inkjet recording technology to dyeing of fabrics. As a result of the present inventors' research so far, as a water-soluble coloring material to be contained in the ink used for dyeing the fabric, considering the adhesion to the fabric and the strong light resistance required for the fabric, chromium It has been found that a gold-containing dye having a molecule such as cobalt or cobalt can be suitably used. Further, the present inventors have further studied these coloring materials. As a result, the metal ions in the molecule are released in the ink, and the kogation is easily formed on the heat generating heater. It has been found that it is necessary to prepare an extremely delicate ink in order to ensure ink ejection performance. However, according to the invention of the present embodiment, even with an ink employing such a coloring material, the occurrence of kogation on the heating heater can be effectively suppressed, and the ejection stability can be improved. Further, as a coloring material used in inks for ink jet recording in the related art, it is possible to greatly widen the application range of coloring materials whose use is limited.
[0059]
Here, specific examples of the gold-containing dye that can be used as a coloring material of the ink according to the present embodiment include, for example, the following coloring materials.
[0060]
CI Acid Yellow 59, 121, 151, 158, 194, 204, 207, 232, 235, 241
[0061]
CI Acid Orange 142, 144, 166, 168
[0062]
CI Acid Red 215, 296, 315, 357, 359, 362, 399
[0063]
CI Acid Violet 90 (see the following structural formula (VI)), 92 (see the following structural formula (VII)), 121,
[0064]
[Outside 13]

[0065]
[Outside 14]

[0066]
CI Acid Blue 167, 193 (see the following structural formula), 229, 284, 296, 300, 335, 338, 342
[0067]
[Outside 15]

[0068]
CI Acid Brown 19, 282, 283, 289, 298, 355, 357, 365, 413, 415
[0069]
CI Acid Black 52, 52: 1 (see the following structural formula IX), 60, 99,
107, 155, 188, 194, 222
[0070]
[Outside 16]

[0071]
CI Acid Green 73, 104, 108
[0072]
(About gold dye and ink pH)
When the above-described gold-containing dye is used as the coloring material in the ink according to the present embodiment, it is preferable to adjust the pH of the ink to 3.5 to 7.5, particularly to 3.5 to 6.5. . That is, by setting the pH of the ink within this range, the ion dissociation of the dye in the ink can be suppressed, and the generation of kogation on the heating heater can be further suppressed. Further, as another example of a coloring material that can be used for the ink according to the present embodiment, for example, the dye structure itself is inferior in heat resistance, and the ink structure is used for inkjet recording using thermal energy in order to easily generate kogation and the like. Dyes of the type described above may also be used. A specific example of such a coloring material is CI Acid Yellow 79, for example.
[0073]
(Specific examples of water-soluble organic solvents)
Next, examples of the water-soluble organic solvent that may be contained in the aqueous medium of the ink according to the present embodiment include, for example, monohydric alcohols such as methanol, ethanol, and isopropyl alcohol; ketones such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; oxyethylene or oxypropylene addition polymers such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol; Alkylene glycols wherein the alkylene group contains 2 to 6 carbon atoms, such as trimethylene glycol, butylene glycol, hexylene glycol; Triols such as hexanetriol; thiodiglycol; glycerin; lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, and triethylene glycol monomethyl (or ethyl) ether. A lower dialkyl ether of a polyhydric alcohol such as triethylene glycol dimethyl (or ethyl) ether or tetraethylene glycol dimethyl (or ethyl) ether; The content of the water-soluble organic solvent is generally in the range of 0 to 40%, preferably 2 to 30% by weight based on the total weight of the ink. When the above medium is used in combination, it can be used alone or as a mixture. Preferred water-soluble organic solvents are monohydric alcohols, ketones, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, thiodiglycol, and the like. Glycol, propylene glycol, dipropylene glycol, tripropylene glycol and derivatives thereof (among others, alkyl ethers thereof).
[0074]
(Other ingredients)
In addition, the ink according to the present embodiment may be added with various other antifoaming agents, viscosity modifiers, surface tension regulators, pH regulators, and the like, as needed, within a range that does not impair the effects of the ink. good.
[0075]
(Second embodiment / addition of urea)
As the ink according to the second embodiment of the present invention, there is an ink further containing urea in the ink according to the above embodiment. According to the ink according to the second embodiment, in addition to the effects achieved by the ink according to the first embodiment, it is possible to provide the ink with improved re-discharge properties as compared with the related art. Here, the re-discharge property refers to an operation of discharging ink from the orifice again after recording is temporarily stopped. The inventors of the present invention have studied from among the water-soluble inks containing water-soluble coloring materials that the ink facing the orifice is solidified while recording is temporarily stopped and the orifice is completely or partially removed. In some cases, it may not be possible to re-discharge ink, or it may be impossible to discharge a predetermined amount of ink in the correct direction. It has been found that the use of ink jet recording apparatuses is diversified in terms of use conditions as the orifices are miniaturized due to the development of ink jet recording apparatuses, and the use of ink jet recording apparatuses in a low-temperature environment is particularly common. However, by further containing urea in the ink according to the present embodiment, it is possible to stabilize the re-discharge property even under the above-described conditions, in addition to the effect exerted by the ink according to the first embodiment. The effect is also obtained.
[0076]
By the way, it is not clear why the above-mentioned effect is obtained by adopting such a configuration. However, BHES in the ink is solid at room temperature, and its proportion in the aqueous medium is 20%.wt%When the temperature exceeds the threshold value, the ink tends to precipitate in the form of wax. Therefore, it is considered that this phenomenon starts with the evaporation of water from the orifice from a microscopic point of view of the ink facing the orifice. On the other hand, since urea greatly enhances the affinity between water and a water-soluble dye, by coexisting BHES and urea, in the ink facing the orifice, the effect of suppressing evaporation of water in the ink from the orifice due to precipitation of BHES due to the precipitation of BHES, This is considered to be due to a synergistic effect with the effect of suppressing a sharp rise in the dye concentration of the ink near the orifice. In this embodiment, the amount of urea is preferably 0.1 to 20% by weight, particularly preferably 0.1 to 15% by weight, based on the total weight of the ink, and the total amount of urea and BHES based on the total weight of the ink. The amount is preferably from 0.2 to 30% by weight, particularly preferably from 0.6 to 25% by weight.
[0077]
(apparatus)
Next, an ink jet recording apparatus that can use the above-described ink and an image recording method using the same will be described.
[0078]
(Head configuration)
FIG. 1 is a schematic cross-sectional view of an embodiment of a head that constitutes one of the main parts of an ink jet recording apparatus that ejects ink by using thermal energy, in a direction perpendicular to an orifice portion from which ink is ejected. FIG. FIG. 2 is a sectional view taken along line AA of FIG. 1 and 2, a head 13 is made of a glass, ceramic or plastic plate having a groove 14 through which ink passes, and a heating head 15 used for thermal recording (a head is shown in the drawings, but the head 13 is not limited to this). Is not obtained). The heating head 15 includes a protective film 16 made of silicon oxide or the like, aluminum electrodes 17-1 and 17-2, a heating resistor layer 18 made of nichrome or the like, a heat storage layer 19, and a substrate 20 having good heat dissipation such as alumina. Is made up of The ink 21 reaches a discharge orifice (fine hole) 22 and forms a meniscus 23 at a predetermined pressure P. When an electric signal is applied to the electrodes 17-1 and 17-2, the area of the heating head 15 indicated by "n" rapidly generates heat, and bubbles are generated in the ink 21 in contact with the area. The ink 23 is ejected from the orifice 22, flies toward a recording medium (for example, paper) 25, adheres to an image recording area of the recording medium 25, and an image is recorded.
[0079]
FIG. 3 shows an external view of a multi-head in which many heads shown in FIG. 1 are arranged. The multi-head is manufactured by closely contacting a glass plate 27 having a multi-groove 26 and a heating head 28 similar to that described with reference to FIG.
[0080]
In the configuration of the head described above, the size of the orifice is not particularly limited, and may be appropriately set according to the desired image quality. However, with the recent demand for higher image quality, miniaturization of the orifice size has been studied. Specifically, for example, miniaturization of the orifice such that the amount of ink ejected from the orifice by one ejection operation is 0.1 to 40 picoliters (pl), particularly 0.1 to 30 pl has been studied. In the orifice of such a size, it is one of the technical goals particularly preferable to form a high-quality image by stably re-discharging the ink after the recording is temporarily stopped. The inks according to the various embodiments of the present invention described above, particularly the inks according to the second embodiment, can be cited as one of extremely effective techniques capable of overcoming this technical goal.
[0081]
Even when the orifice is not miniaturized as described above, the use environment is diversified due to the spread of the ink jet recording apparatus, specifically, for example, an environment where the ambient temperature is 5 ° C. or less (for example, heating in a cold area). When the ink jet recording apparatus is used under indoor or outdoor conditions where ink does not work effectively, ink may not be ejected due to clogging of the orifice as described above. Is one of the important technical goals to be overcome. The ink according to each of the above embodiments, particularly the ink according to the second embodiment, can be cited as one of extremely effective techniques capable of overcoming this technical goal.
[0082]
(Inkjet recording device)
FIG. 4 shows an example of an ink jet recording apparatus incorporating the head according to the present invention. In FIG. 4, reference numeral 61 denotes a blade serving as a wiping member, one end of which is held by a blade holding member and serves as a fixed end, forming a cantilever. The blade 61 is disposed at a position adjacent to the recording area of the recording head, and in this example, is held in a form protruding into the movement path of the recording head. Reference numeral 62 denotes a cap, which is disposed at a home position adjacent to the blade 61 and has a configuration in which the cap moves in a direction perpendicular to the direction in which the print head moves and comes into contact with the discharge port surface to perform capping. Further, 63 is an absorber provided adjacent to the blade 61 and, like the blade 61, is held in a form protruding into the movement path of the recording head. The blade 61, the cap 62, and the absorber 63 constitute an ejection recovery unit 64, and the blade 61 and the absorber 63 remove water, dust, and the like from the ink ejection port surface. Reference numeral 65 denotes a recording head which has ejection energy generating means and performs recording by discharging ink on a fabric facing the ejection port surface provided with the ejection port, and 66 carries the recording head 65 and moves the recording head 65. It is a carriage for. 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). As a result, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and the adjacent area. Reference numeral 51 denotes a paper feed unit for inserting recording paper, and 52 denotes a paper feed roller driven by a motor (not shown). With these configurations, the recording paper is fed to a position facing the discharge port surface of the recording head, and is discharged to a paper discharge unit provided with a discharge roller 53 as recording proceeds.
[0083]
In the above configuration, when the recording head 65 returns to the home position at 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 capping is performed with the cap 62 in contact with the ejection surface of the recording head 65, the cap 62 moves so as to protrude into the movement path of the recording head.
[0084]
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 the position at the time of wiping described above. As a result, the ejection port surface of the recording head 65 is also wiped during this movement. The above-described movement of the print head to the home position is performed not only at the end of printing or at the time of ejection recovery, but also at a predetermined interval to the home position adjacent to the printing area while the printing head moves through the printing area for printing. Then, the wiping is performed along with this movement.
[0085]
(ink cartridge)
FIG. 5 is a diagram illustrating an example of an ink cartridge containing ink supplied to the head via an ink supply member, for example, a tube. Here, reference numeral 40 denotes an ink storage portion that stores the supply ink, for example, an ink bag, and a rubber stopper 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. Reference numeral 44 denotes an absorber for receiving the waste ink. It is preferable for the present invention that the ink container has a liquid contact surface with the ink formed 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 from each other as described above, and may be suitably used in an integrated one as shown in FIG.
[0086]
(Recording unit)
In FIG. 6, reference numeral 70 denotes a recording unit, in which an ink storage unit storing ink, for example, an ink absorber is stored, and a head unit having a plurality of orifices in which the ink in the ink absorber is stored. It is configured to be ejected from 71 as ink droplets. As the material of the ink absorber, it is preferable for the present invention to use polyurethane. Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the recording unit with the atmosphere. This recording unit 70 is used in place of the recording head shown in FIG. 4, and is detachable from the carriage 66.
[0087]
(Ink set)
By the way, the inks according to the various embodiments described above can be, for example, yellow, magenta, cyan, red, green, blue or black inks by selecting a color material. Each ink may be used independently for image recording. Alternatively, an ink set that can be suitably used for forming a color image can be provided by combining two or more different color inks. Also, by combining two or more inks of the same color and containing different color materials, or by combining two or more inks of the same color but having different densities, it is suitable for forming a high gradation image. An ink set that can be used can be provided. When an image is formed using these ink sets, for example, a recording apparatus in which four recording heads shown in FIG. 3 are arranged on a carriage can be used. FIG. 8 shows an embodiment of the present invention. Reference numerals 86, 87, 88 and 89 denote recording heads for ejecting, for example, yellow, magenta, cyan and black inks. The print head is arranged in the above-described printing apparatus, and discharges ink of each color according to a print signal. FIG. 8 shows an example in which four recording heads are used. However, the present invention is not limited to this. For example, as shown in FIG. An embodiment in which image recording is performed is also included.
[0088]
The case where the ink according to the present invention is used in an apparatus that applies thermal energy corresponding to a recording signal to ink and ejects ink from the thermal energy and an image recording method using the apparatus has been described. However, the ink of the present invention can also be used in an ink jet recording apparatus that discharges the ink by mechanical energy and an image recording method using the same, whereby similar excellent effects can be obtained.
[0089]
【Example】
(Examples 1 to 14)
Inks having the compositions shown in Table 1 below were prepared. That is, each material is mixed, stirred for 2 hours, adjusted to a desired pH with 4N-lithium hydroxide (LiOH), and then filtered under pressure through a membrane filter having a pore size of 0.2 μm to obtain each recording ink. Obtained. In the table below, FB2 is C.I. I. Food Black 2 and DY86 are C.I. I. Abbreviation for direct yellow 86.
[0090]
In the compound 1, in the structural formula (V), “L” is the structural formula (15), “X” is the structural formula (16), “R1” and “R2” are a hydrogen atom and —NH2. It is a structural dye.
[0091]
[Table 1]

[0092]
(Reference Examples 1 to 3)
Inks having the compositions shown in Table 2 below were prepared in the same manner as the inks prepared in the examples.
[0093]
[Table 2]

[0094]
For the inks of Examples 1 to 14 and Reference Examples 1 to 3, 6 × 108 shots were made using an inkjet recording head configured so that the amount of ink ejected from one nozzle in one ejection operation was 20 pl. After discharging, the following items were evaluated. The results are shown in Table 3 below.
[0095]
〔Evaluation item]
(1) Droplet size (change in discharge amount)
6 × 10⁸The ink ejection amount per nozzle after ejection and ejection was measured and compared with the initial ink ejection amount of the nozzle.
：: The ink ejection amount after the ejection test is 95% or more compared to the initial stage.
Δ: The ink ejection amount after the ejection test is 80% or more and less than 95% as compared with the initial time.
×: The ink ejection amount after the ejection test is less than 80% compared to the initial stage.
[0096]
(2) Observation of heater surface
6 × 10⁸The head after ejection and ejection was disassembled, and the heater surface was observed with an optical microscope.
：: Almost no kogation is observed.
：: Some kogation is observed, but the level does not affect ejection.
Δ: Many kogation are observed.
[0097]
(3) Image degradation (landing accuracy)
6 × 10⁸After the ejection and ejection, a straight line having a resolution of 600 dpi is recorded on coated paper (trade name: HR101; manufactured by Canon Inc.), and the positional relationship (landing position) of each dot is captured in a video image to form a 600 dpi grid. The deviation from the point (± μm) was measured.
：: landing accuracy is less than ± 10 μm.
Δ: The landing accuracy is ± 10 μm or more and less than 15 μm.
X: The landing accuracy is ± 15 μm or more.
[0098]
[Table 3]

[0099]
From the results shown in Table 3 above, after performing severe recording such as discharging 6 × 108 shots using an ink jet printing head configured to reduce the amount of ink ejected from one nozzle by one ejection operation. It was also found that the generation of kogation on the surface of the heating heater was effectively suppressed.
[0100]
Further, based on the results of Examples 1 to 3 and 12 and Reference Example 1, and the results of Examples 4 to 5 and 13 and Reference Example 2, at least one selected from bishydroxyethyl sulfone and dicarboxylic acids, salts thereof, tricarboxylic acids and salts thereof. The use of one of them can further improve the three of the change in the ejection amount, the kogation property, and the landing accuracy. In particular, the combined use of bishydroxyethyl sulfone and citric acid could further suppress the occurrence of kogation on the heater surface.
[0101]
(Examples 15 to 20)
Inks having the same composition as the compositions of Examples 6 to 11 were prepared, and used as inks of Examples 15 to 20. Commercially available copy paper using an ink jet printer (trade name: BJ130; manufactured by Canon Inc.) of a type in which each ink is used to apply thermal energy to the ink by a heating heater to discharge the ink. Then, recording was performed at a driving frequency of 2 kHz, and the ink re-ejection property when the ejection operation was performed again after the recording was temporarily stopped was evaluated. The printer head used here was configured so that the amount of ink ejected from one nozzle in one ejection operation was about 60 pl. The evaluation conditions are as follows. After printing each of the above inks for 1 minute continuously in an environment of room temperature 0 ° C. and humidity 25 ± 5% using the above printer, the printing is stopped for 30 seconds, When the alphanumeric characters were printed again, the printing defects such as blurred or missing characters were observed. At this time, the head temperature was 35 ± 5 ° C. The results are shown in Table 4 below. The evaluation criteria are as follows.
：: No blurring or chipping is recognized from the first character at the time of re-recording.
Δ: A part of the first character at the time of re-recording is blurred or missing.
X: The first character at the time of re-recording cannot be printed at all.
[0102]
[Table 4]

[0103]
(Examples 21 to 24)
Inks having the compositions shown in Table 5 below were prepared in the same manner as the inks of Examples 1 to 14 above.
[0104]
[Table 5]

[0105]
(Reference Example 4 ~6)
Inks having the compositions shown in Table 6 below were prepared in the same manner as the inks of Examples 1 to 14.
[0106]
[Table 6]

[0107]
Examples 21 to 24 and Reference Examples 4 to6Using the head for a bubble jet card printer (trade name: P-400CII; manufactured by Canon Inc.), the ink was evaluated for kogation, ejection stability, and the presence or absence of heater disconnection. The recording head used at this time ejects about 50 pl of ink in one ejection operation per nozzle. The results are shown in Table 7 below. The evaluation criteria are as follows.
[0108]
(1) Koge property
After continuous printing of 2 × 108 pulses was performed with 10 nozzles, when the head was disassembled and the heater surface was observed with an optical microscope, the kogation on the heater surface was evaluated according to the following criteria.
：: No kogation on the heater surface was observed at all.
C: Some kogation is observed on the edge of the heater.
X: kogation is observed on the entire surface of the heater.
[0109]
(2) Discharge stability
When continuous printing of 2 × 108 pulses was performed using 10 nozzles, the amount of the discharged liquid and the decrease in the discharging speed were measured and evaluated according to the following criteria.
：: No decrease in discharge amount occurs at all.
Δ: The discharge amount after the durability decreased from 10% to less than 50% with respect to the initial discharge amount.
X: The discharge amount after the durability was reduced by 50% or more with respect to the initial discharge amount, or the discharge became impossible.
[0110]
(3) Disconnection of heater
When continuous printing of 5 × 107 pulses was performed with 16 nozzles, the degree of disconnection of the heater was evaluated according to the following criteria.
：: No disconnection was observed.
X: Disconnection was observed in one or more nozzles.
[0111]
[Table 7]

[0112]
【The invention's effect】
According to the embodiment of the present invention as described above,
The generation of kogation on the heating heater can be effectively prevented even by long-time recording, and the ejection stability can be improved. Further, by improving the ejection stability, it is possible to stably record a high-quality image.
[0113]
In addition, the occurrence of kogation on the heating heater can be effectively prevented, the ejection stability can be improved, and the re-ejection property of the ink after the recording is temporarily stopped can also be improved.
[0114]
Further, high-quality images can be stably recorded on various recording media, and high-quality images can be stably formed under various use environments. In addition, even when the image quality is improved by miniaturizing the orifice to further improve the quality of the recorded image, the kogation on the heating heater is suppressed, and the re-discharge property of the ink is improved. A stable image can be recorded.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing one embodiment of a head of an ink jet recording apparatus.
FIG. 2 is a sectional view taken along line AA of FIG.
FIG. 3 is a schematic explanatory diagram of a multi-head.
FIG. 4 is a schematic perspective view showing one embodiment of an ink jet recording apparatus.
FIG. 5 is a longitudinal sectional view showing one embodiment of an ink cartridge.
FIG. 6 is a schematic perspective view showing another example of the configuration of the inkjet recording head.
FIG. 7 is a schematic explanatory view of a recording head to which four ink cartridges are attached.
FIG. 8 is a schematic explanatory view showing a configuration in which four recording heads are arranged on a carriage.
[Explanation of symbols]
13 head
14 Ink groove
15 Heating head
16 Protective film
17-1 and 17-2 electrodes
18 Heating resistor tank
19 Thermal storage layer
20 substrates
21 ink
22 Discharge orifice
23 Meniscus
24 ink drops
25 Recording material
26 Multi Groove
27 glass plate
40 ink bags
42 stopper
44 Ink absorber
45 ink cartridge
51 Paper feed unit
52 Paper feed roller
53 Paper ejection roller
61 blade
62 Cap
63 Ink absorber
64 Discharge recovery section
65 Recording Head
66 Carriage
67 Guide shaft
68 motor
69 belt
70 Recording unit
71 Head
72 Atmospheric communication port
80 Ink channel
81 Orifice plate
82 diaphragm
83 Piezoelectric element
84 substrate
85 Discharge port
86, 87, 88, 89 recording head

Claims (28)

An ink comprising: an aqueous medium containing at least one substance selected from dicarboxylic acids, salts of dicarboxylic acids, tricarboxylic acids and salts of tricarboxylic acids, bishydroxyethyl sulfone, and a water-soluble coloring material. The dicarboxylic acid in the ink, salts of dicarboxylic acids, the ink of claim 1, wherein the total amount of salts of tricarboxylic acids and tricarboxylic acids is not more than 0.7%, based on the total weight of the ink. 3. The ink according to claim 1, wherein the substance is citric acid. The ink according to any one of claims 1 to 3 , wherein the aqueous medium contains water. The ink according to any one of claims 1 to 4 , wherein the aqueous medium contains water and a water-soluble organic solvent. The ink according to any one of claims 1 to 5 , wherein the ink further contains urea. The ink according to any one of claims 1 to 6 , wherein the coloring material is a dye having one or more -COOM (M represents an alkali metal or ammonium) in a molecule. The ink according to claim 7 , wherein the pH of the ink is 9.5 to 12. The ink according to any one of claims 1 to 6 , wherein the coloring material is a water-soluble gold-containing dye. The ink according to claim 11 , wherein the pH of the ink is 3.5 to 7.5. The ink according to claim 10 , wherein the pH of the ink is 3.5 to 6.5. The ink according to what Re one of claims 1 to 11 wherein the ink is for inkjet. Dicarboxylic acid, a salt of dicarboxylic acid, at least one substance selected from tricarboxylic acid and a salt of tricarboxylic acid, bishydroxyethyl sulfone, and an ink containing section containing an ink containing a water-soluble coloring material in an aqueous medium. An ink cartridge, comprising: an ink cartridge; 14. The ink cartridge according to claim 13 , wherein the total amount of the dicarboxylic acid, dicarboxylic acid salt, tricarboxylic acid, and tricarboxylic acid salt in the ink is 0.7% or less based on the total weight of the ink. Dicarboxylic acid, a salt of dicarboxylic acid, at least one substance selected from salts of tricarboxylic acid and tricarboxylic acid, bishydroxyethyl sulfone, and an ink containing section containing an ink containing a water-soluble coloring material in an aqueous medium, A recording unit comprising: means for applying the recording ink to a recording medium; and means for supplying the ink to the means. 16. The recording unit according to claim 15 , wherein the total amount of the dicarboxylic acid, dicarboxylic acid salt, tricarboxylic acid and tricarboxylic acid salt in the ink is 0.7% or less based on the total weight of the ink. A recording unit comprising: an ink storage unit that stores the ink according to claim 12 ; and a recording head that discharges the ink by an inkjet method. Ink containing at least one substance selected from dicarboxylic acid, dicarboxylic acid salt, tricarboxylic acid and tricarboxylic acid salt, bishydroxyethyl sulfone, and a water-soluble first colorant in an aqueous medium, and a second color An ink set in which the first and second color materials are each selected from yellow, magenta, cyan, black, red, blue, and green inks. An ink set characterized by two color materials. The dicarboxylic acid in the ink, the salt of a dicarboxylic acid, an ink set according to claim 21, wherein the total amount of salts of tricarboxylic acids and tricarboxylic acids is not more than 0.7%, based on the total weight of the ink. 20. The ink set according to claim 18, wherein each ink constituting the ink set is an ink jet ink. Dicarboxylic acid, at least one substance selected from salts of dicarboxylic acids, tricarboxylic acids and salts of tricarboxylic acids, bishydroxyethyl sulfone, and an ink containing a water-soluble coloring material in an aqueous medium, in an image forming area of the recording medium. An image recording method comprising a step of applying. An image recording method, comprising a step of applying the ink according to claim 12 to a recording medium by an inkjet method. A dicarboxylic acid, a salt of a dicarboxylic acid, at least one substance selected from a tricarboxylic acid and a salt of a tricarboxylic acid, bishydroxyethyl sulfone, and a water-soluble coloring material in an aqueous medium; An ink containing section containing an ink in which the total amount of tricarboxylic acid and a salt of tricarboxylic acid is 0.7% or less based on the total weight of the ink, means for applying the ink to a recording medium, and Image recording, comprising: a recording unit having means for supplying the ink to the means; and means for operating from a means for applying the recording ink to a recording medium in response to a recording signal. apparatus. An image recording apparatus, comprising: an ink storage section storing the ink according to claim 12; and a recording head for discharging the ink. Dicarboxylic acid, a salt of dicarboxylic acid, at least one substance selected from tricarboxylic acid and a salt of tricarboxylic acid, bishydroxyethyl sulfone, urea and a water-soluble coloring material contained in an aqueous medium, the dicarboxylic acid, a salt of dicarboxylic acid, An ink containing section containing an ink in which the total amount of tricarboxylic acid and a salt of tricarboxylic acid is 0.7% or less based on the total weight of the ink, and means for discharging the recording ink from an orifice to a recording medium And a means for supplying the ink to the recording head, wherein the recording head is capable of discharging 0.1 to 40 picoliters of ink from the orifice in one discharge operation. The ink using an image recording apparatus including a unit and means for operating the recording unit in response to a recording signal. Image recording method characterized by comprising the step of attaching to the image recording area of the medium. A dicarboxylic acid, a salt of a dicarboxylic acid, at least one substance selected from a tricarboxylic acid and a salt of a tricarboxylic acid, bishydroxyethyl sulfone, urea and a water-soluble coloring material contained in an aqueous medium, wherein the salt of the dicarboxylic acid and the dicarboxylic acid; An ink containing section containing an ink in which the total amount of tricarboxylic acid and a salt of tricarboxylic acid is 0.7% or less based on the total weight of the ink, for discharging the recording ink from an orifice to a recording medium. A recording head having means for supplying the ink to the recording head, and the recording head is configured to be able to eject 0.1 to 40 picoliters of ink from the orifice in one ejection operation. An image recording apparatus comprising: a recording unit; and means for operating the recording unit in response to a recording signal. A dicarboxylic acid, a salt of a dicarboxylic acid, at least one substance selected from a tricarboxylic acid and a salt of a tricarboxylic acid, bishydroxyethyl sulfone, urea and a water-soluble coloring material in an aqueous medium, wherein the salt of the dicarboxylic acid and the dicarboxylic acid; An ink containing section containing an ink in which the total amount of tricarboxylic acid and a salt of tricarboxylic acid is 0.7% or less based on the total weight of the ink, for discharging the recording ink from an orifice to a recording medium. A recording head having means for supplying the ink to the recording head, and the recording head is configured to be able to eject 0.1 to 40 picoliters of ink from the orifice in one ejection operation. A recording unit, characterized in that: Using heater energy is applied to the ink, a kogation reducing method of the the energy onto the heat generating heater of the ink jet printer system of ejecting the ink from an orifice, as the ink, to claim 13 A method for reducing kogation adhesion, comprising using the ink described in the above.

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