JP3830219B2 - Ink for ink jet recording and recording method - Google Patents

Description

（式中、
Ｒ¹およびＲ³は独立してＨまたはＣＨ₃を表し、
Ｒ²はその構造中にアルキル基（好ましくはＣ₁ 〜₂₁アルキル）、水酸基、カルボキシル基およびスルホン酸基から選ばれる一種以上の基を含んでなる基を表わす）で表わされる繰返し単位を含んでなる共重合体を含んでなる、エポキシ基含有アクリル系樹脂エマルジョンがあげられる。この樹脂は、共重合の態様によっては制限されず、例えばブロックコポリマ、ランダムコポリマなどであることができる。
【００３３】
また、このような共重合体の末端は、この共重合体が高分子ゆえその性質に本質的な影響を与えるものではないが、一般的には重合開始剤の切片が結合したものとなろう。このような重合開始剤の切片としては、例えば過硫酸アンモニウム、過硫酸カリウムなどの重合開始剤の切片、具体的には−ＯＳＯ₃Ｈなどがあげられる。
【００３４】
Ｒ²の好ましい例としては、−ＯＨ、−ＣＯＯＨ、−ＣＯＯ−Ｒ（ここで、Ｒは直鎖または分岐鎖状のアルキル基、好ましくはＣ_1-12のアルキル基を表し、更にこのアルキル基上の一以上の水素原子は水酸基、ホスホノ基、またはスルホン酸基で置換されていてもよい）、スルホン酸基で置換されたアリール基（例えば、フェニル基、トリル基）が挙げられる。Ｒ²として表わされる基の具体例としては、−ＯＨ、−ＣＯＯＨ、−ＣＯＯＣＨ₂ＣＨ₂ＯＨ、−ＣＯＯＣＨ₂ＣＨ（ＣＨ₃）ＯＨ、−ＣＯＯＣＨ₂ＣＨ₂ＰＯ（ＯＨ）₂、−Ｃ₆Ｈ₅ＳＯ₃Ｈ、−ＣＯＯＣＨ₂ＣＨ₂ＳＯ₃Ｈ、−ＣＯＯＣＨ₃、−ＣＯＯＣ₂Ｈ₅、−ＣＯＯＣ₄Ｈ₉、−ＣＯＯＣ₆Ｈ₁₃、−ＣＯＯ（ＣＨ₂）₁₁ＣＨ、−ＣＯＯＣＨ₂ＣＨ（ＣＨ₃）ＣＨ₂Ｃ（ＣＨ₃）₃等が挙げられる。ここで、Ｒ²に含まれることのある水酸基、カルボキシル基、またはスルホン酸基はエポキシ基と反応可能な官能基である。
【００３５】
また、この樹脂エマルジョンとして市販のものを用いることも可能であり、その例としてはアルマテックスＺ１１６（三井東圧化学株式会社製）、ニューコートＳ−２１７０およびＳ−１０８０（新中村化学工業株式会社製）、バナテックス＃９５２およびＨＧ−９（新中村化学工業株式会社製）、Ｐｉｅｓｔｅｘ Ｂ−３（新中村化学工業株式会社製）があげられる。
【００３６】
本発明によるインク組成物におけるエポキシ基含有化合物の含有量は、インク組成物の１〜１０重量％程度が好ましく、より好ましくは１〜５重量％の範囲である。
【００３７】
なお、本発明において用いられるインク組成物は、好ましくは後記するような樹脂エマルジョンを含んでなるが、前記したエポキシ基含有化合物がエポキシ基含有樹脂エマルジョンである場合、このエポキシ基含有化合物はこの樹脂エマルジョンの作用をも兼ねるものであり、更に別の成分の樹脂エマルジョンを含まなくともよい。しかし、本発明の好ましい態様によれば、エポキシ基含有樹脂エマルジョンに加え、更に樹脂エマルジョンが添加されるのが好ましい。
【００３８】
樹脂エマルジョン
また、本発明の好ましい態様によれば、本発明において用いられるインク組成物は樹脂エマルジョンを含んでなるのが好ましい。樹脂エマルジョンの添加によって特に印刷物の耐擦性を向上させることができる。好ましく用いられる樹脂エマルジョンは、連続相が水であり、分散相の樹脂成分がエポキシ基を含まないものである。なお、前記したように、エポキシ基含有化合物がエポキシ基含有樹脂エマルジョンである場合、この樹脂エマルジョンの添加は必須ではない。このような樹脂成分としては、アクリル系樹脂、酢酸ビニル系樹脂、スチレン−ブタジエン系樹脂、塩化ビニル系樹脂、アクリル−スチレン系樹脂、ブタジエン系樹脂、スチレン系樹脂などがあげられる。
【００３９】
また、市販の樹脂エマルジョンとしては、例えばマイクロジェルＥ−１００２、Ｅ−５００２（スチレン−アクリル系樹脂エマルジョン、日本ペイント株式会社製）、ボンコート４００１（アクリル系樹脂エマルジョン、大日本インキ化学工業株式会社製）ボンコート５４５４（スチレン−アクリル系樹脂エマルジョン、大日本インキ化学工業株式会社製）、ＳＡＥ−１０１４（スチレン−アクリル系樹脂エマルジョン、日本ゼオン株式会社製）、サイビノールＳＫ−２００（アクリル系樹脂エマルジョン、サイデン化学株式会社製）、などがあげられる。
【００４０】
本発明の好ましい態様によれば、これらの樹脂は親水性部分と疎水性部分とを併せ持つ重合体であるのが好ましい。また、これらの樹脂成分の粒子径はエマルジョンを形成する限り特に限定されないが、１５０ｎｍ程度以下が好ましく、より好ましくは５〜１００ｎｍ程度である。
【００４１】
これらの樹脂エマルジョンは、重合反応によって得られた重合物に、界面活性剤と水を加えて乳化する、あるいは、モノマーを界面活性剤存在下の水中で乳化重合することによって得ることができる。例えば、アクリル系樹脂エマルジョンまたはスチレン−アクリル系樹脂のエマルジョンは、（メタ）アクリル酸エステルまたはスチレンと（メタ）アクリル酸エステルとを界面活性剤等の乳化剤の存在下で乳化重合することによって得ることができる。樹脂成分と界面活性剤との混合の割合は、通常１０：１〜５：１程度とするのが好ましい。界面活性剤の使用量が前記範囲にあることでより良好なインクの耐水性、浸透性が得られる。界面活性剤は特に限定されないが、好ましい例としてはアニオン性界面活性剤（例えばアルキルサルフェート、アルキルアリルスルホネート、ジアルキル サクシネート、アルキルナフタレンスルホネートなど）、ＨＬＢ１０以上の非イオン性界面活性剤（例えば、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アルキルアリルエーテルなど）があげられ、これらを単独または二種以上混合して用いることができる。
【００４２】
また、分散相成分としての樹脂と水との割合は、樹脂１００重量部に対して水６０〜４００重量部、好ましくは１００〜２００の範囲が適当である。
【００４３】
本発明に使用するインク組成物は、樹脂エマルジョンを、その樹脂成分がインク組成物の０．１〜４０重量％となるよう含有するのが好ましく、より好ましくは１〜２５重量％の範囲である。
【００４４】
インクジェット記録方法および記録装置
本発明の好ましい態様によれば、本発明によるインク組成物は、フッ素系高分子を含んだメッキ層をその表面に有するノズルプレートを備えた記録ヘッドを用いたインクジェット記録方法に好ましく用いられる。上記インク組成物とこのような記録ヘッドを組み合わせることで、インク滴の飛行曲がりを極めて低いレベルに抑制することができ、その結果安定な印字が可能となるとの利点が得られる。
【００４５】
図１のインクジェット記録装置は、インク組成物をタンクに収納し、インク組成物がインクチューブを介して記録ヘッドに供給される態様である。すなわち、記録ヘッド１とインクタンク２とがインクチューブ３で連通される。
【００４６】
記録ヘッド１は、キャリッジ４に搭載され、モータ５で駆動されるタイミングベルト６によってガイド９にガイドされて移動する。一方、記録媒体である紙７はプラテン８によって記録ヘッド１と対面する位置に置かれる。なお、この態様においては、キャップ１０が設けられてなる。このキャップ１０には吸引ポンプ１１が連結され、いわゆるクリーニング操作を行う。吸引されたインク組成物はチューブ１２を介して廃インクタンク１３に溜め置かれる。
【００４７】
記録ヘッド１のノズルプレートの拡大図を図２に示す。ノズルプレート１０１は、インク組成物が吐出される複数のノズル１０２が縦方向に並んで設けられてなる。さらに、このノズル１０２付近の断面拡大図を図３として示す。
【００４８】
図３においてノズルプレート１０１は、基材１０３と、その上に設けられたフッ素系高分子を含むメッキ層１０４とを含んでなる。このノズルプレート１０１は接着層１０５を介してノズル基体１０６に接着され、インク室１０７が形成される。インク室１０７中はインク組成物により満たされ、例えばそのメニスカスは図中のＭで示されるように形成される。インク室１０７中のインク組成物は図示されてないアクチュエータによって圧力を受け、液滴となってノズル１０２より図中の矢印の方向に吐出される。
【００４９】
基材１０３は、金属、セラミックス、シリコン、ガラス、プラスチック等で形成されてよく、好ましくはチタン、クロム、鉄、コバルト、ニッケル、銅、亜鉛、スズ、金等の単一もしくはニッケル−リン合金、スズ−銅−リン合金（リン青銅）、銅−亜鉛合金、ステンレス鋼等の合金、およびポリカーボネイト、ポリサルフォン、ＡＢＳ樹脂（アクリルニトリル・ブタジエン・スチレン共重合）、ポリエチレンテレフタレート、ポリアセタール、各種の感光性樹脂によって形成される。
【００５０】
基材１０３の表面へのフッ素系高分子を含むメッキ層１０４は、次のような共析メッキ処理により形成される。まず、基材表面を酸で洗浄した後、この基材をマトリックス金属イオンを含む水溶液にフッ素系高分子の粒子を分散させた液中に浸漬する。これにより、フッ素系高分子粒子が、マトリックス金属イオンを媒介して基材１０３の表面に付着し、皮膜を形成する。その後、この皮膜をフッ素系高分子の融点以上の温度、例えば３５０℃程度以上の温度に加熱し、均質なメッキ層１０４を形成することができる。ここで、フッ素系高分子の例としては、ポリテトラフルオロエチレン、ポリパーフルオロアルコキシブタジエン、ポリフルオロビニリデン、ポリフルオロビニル、およびポリジパーフルオロアルキルフマレート、並びに下記の式（Ｉ）〜（Ｖ）で表される高分子を挙げることができる。これらの高分子は単独でも、複数混合して使用されてもよい。
【００５１】
【化３】

（ここで、Ｘ₁、Ｘ₂、Ｘ₃、およびＸ₄の少なくとも二つは、フッ素原子またはパーフルオロアルキルを表し、他はアルキル基、好ましくはＣ_1-20アルキル基、を表し、Ｒ₁、Ｒ₂、Ｒ₃、およびＲ₄は水素原子およびハロゲン原子を含む炭化水素を表す）
【化４】

（ここで、Ｘ１はＣＯＯＣ_mＦ_2m+1を表し、ｍは１〜２０を表す）
【化５】

（ここで、Ｒはアルキル基、好ましくはＣ_1-20アルキル基、を表す）
【化６】

（ここで、Ｒはアルキル基、好ましくはＣ_1-20アルキル基、を表す）
【００５２】
また、マトリックス金属イオンは、ニッケル、銅、銀、亜鉛、錫の金属イオンが好ましく、ニッケル、ニッケル−コバルト合金、ニッケル−リン合金、ニッケル−ホウ素合金が、その表面硬度が大で、しかも対摩耗性に優れておりより好ましいものとして挙げられる。
【００５３】
フッ素系高分子を含むメッキ層１０４は、その良好な撥インク性およびインク吐出口の径の精度を確保するため、１〜１０μｍの範囲の膜厚とされるのが好ましい。また、メッキ層１０中のフッ素系高分子の共析量は、メッキ層中６０vol％以下、特に１０〜５０vol％程度とされるのが好ましい。
【００５４】
共析メッキ処理は、無電解法、電解法のいずれによってもよいが、インク組成物中のイオン種の影響を受けにくくかつ耐久性の高いメッキ層を形成可能な電解法が好ましい。さらに、フッ素系高分子の融点以上の温度に加熱する際、ノズルプレート１０１の反りを防ぐため、１００gf／cm²以上、好ましくは、５００gf／cm²の圧力を加えるのが好ましい。
【００５５】
【実施例】
以下の実施例により本発明をさらに詳細に説明するが、本発明はこれら実施例に限定されるものではない。
【００５６】
インク組成物の調製
以下のインク組成物を調製した。すなわち、カーボンブラックと分散剤とを混合し、サンドミル（安川製作所製）中で、ガラスビーズ（直径１．７ｍｍ、混合物の１．５倍量（重量））とともに２時間分散させた。その後ガラスビーズを取り除き、他の上記成分を加え、常温で２０分間攪拌した。５μｍのメンブランフィルターでろ過して、インクジェット記録用インクを得た。
【００５７】
例１
カーボンブラックＭＡ７（三菱化成株式会社製） ５重量％
スチレン−アクリル共重合体（分散剤） １重量％
スノーテックスＳ（コロイダルシリカ、ＳｉＯ₂含有量３０％、日産化学製）
１０重量％
グリセリン １０重量％
２−ピロリドン ２重量％
純水 残量
【００５８】
例２
カーボンブラックRaven1080(コロンビアン・カーボン株式会社） ５重量％
スチレン−アクリル共重合体（分散剤） １重量％
スノーテックスＳ（コロイダルシリカ、ＳｉＯ₂含有量２０％、日産化学製）
０．５重量％
スクロース ０．７重量％
マルチトール ６．３重量％
グリセリン １０重量％
２−ピロリドン ２重量％
純水 残量
【００５９】
例３
カーボンブラックＭＡ７（三菱化成株式会社製） ５重量％
スチレン−アクリル共重合体（分散剤） １重量％
アルミナゾル−200 （Ａｌ₂Ｏ₃含有量１０％、日産化学製） ５重量％
ボンコート４００１ ５重量％
（アクリル系樹脂エマルジョン、樹脂成分５０％、ＭＦＴ＝５℃、大日本インキ株式会社製）
グリセリン １０重量％
２−ピロリドン ２重量％
純水 残量
【００６０】
例４
カーボンブラックRaven1080(コロンビアン・カーボン株式会社） ５重量％
スチレン−アクリル共重合体（分散剤） １重量％
コロイダルシリカＳ ５重量％アルマテックスＺ１１６ ３重量％
（エポキシ基含有アクリル樹脂エマルジョン、樹脂成分５０％、三井束圧化学株式会社製）
グリセリン １０重量％
２−ピロリドン ２重量％
純水 残量
【００６１】
例５
カーボンブラックRaven1080(コロンビアン・カーボン株式会社） ５重量％
スチレン−アクリル共重合体（分散剤） １重量％
グリセリン １０重量％
２−ピロリドン ２重量％
純水 残量
【００６２】
評価試験
以上のインク組成物の性能を以下のように評価した。
【００６３】
評価１：耐擦性
インクジェットプリンターＭＪ−７００Ｖ２Ｃを用いて、ＸｅｒｏｘＰ紙（ゼロックス株式会社製）に印刷し、印刷物を２４時間自然乾燥させた。その印刷物を２５℃、５０ＲＨの環境で指で擦り、印刷の汚れの発生の有無を目視で観察した。その結果は、表に示される通りであった。表中、
○：印刷の汚れが観察されない場合、
△：印刷の汚れが若干発生するが、文字の判別は可能な場合
×：印刷の汚れで文字の判別ができない場合である。
【００６４】
評価２：専用メディアへの定着性
インクジェットプリンターＭＪ−７００Ｖ２Ｃを用い、インクをＭＪ−７００Ｖ２Ｃ用専用光沢フィルム（セイコーエプソン株式会社製）に印刷した後、印刷物を２４時間自然乾燥させる。その印刷物を２５℃、５０ＲＨの環境で指で擦り、印刷の汚れ、着色剤の剥離の発生の有無を目視で観察した。その結果は、表中に示される通りである。表中、
○：印刷の汚れ、着色剤の剥離が観察されない場合
△：印刷の汚れが若干発生するが、着色剤の剥離は観察されない場合
×：印刷の汚れ、着色剤の剥離がともに発生する場合
【００６５】
評価３：印刷ムラ
インクジェットプリンターＭＪ−７００Ｖ２Ｃで、以下の各紙に１００％ｄｕｔｙで印刷を行なった。
【００６６】
評価紙
（１）Ｒｉｃｏｐｙ６２００紙（リコー株式会社製）
（２）Ｃａｎｎｏｎ ｄｒｙ紙（キャノン株式会社製）
Ｍａｃｂｅｔｈ ＰＣＭIIを用いて印刷部分の任意の５点のＯＤ値を測定しその平均を求めた。
【００６７】
この手順を５回繰り返し、５つの平均値の最大値と最小値を求めた。この差が０．５未満であると実用上問題なく、さらには０．４未満が好ましい。その結果は、表に示される通りである。表中、
○：ＯＤ値の差が０．３未満
△：ＯＤ値の差が０．３以上０．４未満
×：ＯＤ値の差が０．４以上
【００６８】
評価４：吐出安定性
インクジェットプリンターＭＪ−７００Ｖ２Ｃ（セイコーエプソン株式会社製）を用いてインクを充填し、常温でアルファベット文字を連続印字し、ドット抜け、およびインクの飛び散りを観察し、１０回以上発生するまでの時間を調べた。その結果は表に示される通りである。表中、
◎：４８時間以上ドット抜けまたはインクの飛び散りが１０回発生しない。
○：２４〜４８時間の内にドット抜けまたはインクの飛び散りが１０回発生する。
△：１〜２４時間の内にドット抜けまたはインクの飛び散りが１０回発生する。
×：１時間以下にドット抜けまたはインクの飛び散りが１０回以上発生する。
【表１】

【図面の簡単な説明】
【図１】本発明による方法を実施するインクジェット記録装置を示す図であって、この態様においては記録ヘッドとインクタンクがそれぞれ独立してなり、インク組成物はインクチューブにより記録ヘッドに供給される。
【図２】本発明によるインク組成物と組み合わせて好ましく用いられる記録ヘッドのノズルプレートの拡大図であり、ノズルプレート１０１は、インク組成物が吐出される複数のノズル１０２が縦方向に並んで設けられてなる。
【図３】ノズルプレート１０１に設けられたノズル１０２付近の断面拡大図である。ノズルプレート１０１は、基材１０３と、その上に設けられたフッ素系高分子を含むメッキ層１０４とを含んでなる。
【符号の説明】
１ 記録ヘッド
２ インクタンク
３ インクチューブ
１０１ ノズルプレート
１０２ ノズル
１０３ 基材
１０４ フッ素系高分子を含むメッキ層[0001]
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION The present invention relates to an ink composition used for an ink jet recording method.
[0002]
Background art The inkjet recording method is a printing method in which printing is performed by causing droplets of an ink composition to fly and adhere to a recording medium such as paper. This method has a feature that a high-resolution and high-quality image can be printed at a high speed with a relatively inexpensive apparatus. In general, an ink composition used for ink jet recording generally contains water as a main component and contains a colorant and a wetting agent such as glycerin for the purpose of preventing clogging.
[0003]
In general, dyes and pigments are used as the colorant. Dyes are widely used because of their good water solubility. However, the good water solubility of the dye makes the printed material poor in water resistance. On the other hand, since the pigment is essentially water-insoluble, a printed matter having excellent water resistance can be realized, but it is necessary to stably disperse it in the ink composition. Also, the printed material may have inferior abrasion resistance than the dye. Furthermore, printing unevenness may occur in a printed matter obtained with an ink composition containing a pigment as a colorant. Printing unevenness is a disturbance in the color density of a printed matter resulting from uneven coloring components on paper. Printing unevenness is not a big problem with normal-size characters, but it is an important problem in applications where graphics, graphs, etc. must be printed.
[0004]
Summary of the Invention
The present inventors have now found that a good image can be realized by printing a pigment-based ink composition containing a combination of a pigment and an inorganic oxide colloid by an inkjet recording method. Furthermore, it has been found that a better image can be realized by combination with a recording head including a nozzle plate subjected to a specific water repellent treatment. The present invention is based on such knowledge.
[0005]
Accordingly, an object of the present invention is to provide an ink composition for ink jet recording capable of realizing a good image.
[0006]
A further object of the present invention is to provide an ink jet recording method capable of realizing a good image.
[0007]
The ink composition for inkjet recording according to the present invention contains at least a pigment, an inorganic oxide colloid, and an aqueous solvent.
[0008]
The ink jet recording method according to the present invention is an ink jet recording method for performing printing by ejecting droplets of an ink composition from a recording head and attaching the droplets to a recording medium. The ink composition is used.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Ink composition The ink composition used in the present invention contains at least a pigment, an inorganic oxide colloid, and an aqueous solvent.
[0010]
According to the ink composition of the present invention, a printed matter having excellent abrasion resistance and color unevenness can be obtained. According to a preferred embodiment of the present invention, surprisingly, stable printing can be achieved by combining with a recording head having a nozzle plate having a plating layer containing a fluorine-based polymer, which will be described later. More specifically, there is an advantage that the flying curve of ink droplets can be suppressed to an extremely low level, and as a result, stable printing becomes possible.
[0011]
Inorganic oxide colloid The inorganic oxide colloid (also referred to as inorganic oxide sol) used in the present invention is composed of water or an organic solvent mixed well with water, and the dispersoid is an inorganic oxide. It means a colloidal solution consisting of ultrafine particles. Examples of the inorganic oxide include, but are not limited to, high molecular weight silicic acid anhydride (SiO ₂ ) and alumina (Al ₂ O ₃ ). The particle size of the inorganic oxide ultrafine particles is generally about 1 to 100 nm, preferably 1 to 20 nm, and more preferably 1 to 10 nm. The dispersion medium of the inorganic oxide colloid is generally water or a mixed solvent with an organic solvent having good compatibility with water, such as methanol, ethanol, isopropyl alcohol, n-propanol and the like. The inorganic oxide colloid can be obtained by dispersing ultrafine particles of the inorganic oxide in water or in the organic solvent. A dispersion in which ultrafine particles of the above inorganic oxide are dispersed in water is called an aqueous sol, and a dispersion in an organic solvent is called an organosol.
[0012]
As such an inorganic oxide colloid, a commercially available product can be used. Specific examples include SNOWTEX S, SNOWTEX N, SNOWTEX C, SNOWTEX SS, SNOWTEX XS, SNOWTEX 20, SNOWTEX 30, and SNOWTEX in which ultrafine particles of high molecular weight silicic acid are dispersed in water. 40 (manufactured by Nissan Chemical Co., Ltd.), Cataloid SI-350, Cataloid SI-500, Cataloid SI-30, Cataloid S-20L, Cataloid S-20H, Cataloid S-30L, Cataloid S-30H, Cataloid SI-40 (above DuPont) Manufactured) and the like. Examples include alumina sol 100, alumina sol 200, and alumina sol 520 (manufactured by Nissan Chemical Co., Ltd.) in which ultrafine alumina particles are dispersed in water. OSCAL-1432 (isopropyl alcohol sol; manufactured by Catalyst Kasei Kogyo Co., Ltd.) in which ultrafine particles of high molecular weight silicic acid are dispersed in an organic solvent can also be used. The pH of the above-mentioned commercially available inorganic oxide colloid solution is often adjusted to be acidic or alkaline. This is because the stable dispersion region of the inorganic oxide colloid exists on the acidic side or alkaline side. When a commercially available inorganic oxide colloid solution is added to the ink, the pH of the stable dispersion region of the inorganic oxide colloid is It is necessary to add in consideration of the pH of the ink.
[0013]
The amount of the inorganic oxide colloid added may be determined as appropriate, but for example, it is preferably about 0.1 to 15% by weight, more preferably about 0.5 to 5.0% by weight of the ink composition. A plurality of inorganic oxide colloids may be added.
[0014]
Pigment The colorant contained in the ink composition used in the present invention is a pigment. Either inorganic pigments or organic pigments can be used. As the inorganic pigment, in addition to titanium oxide and iron oxide, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used. Organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazines). Pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, etc.), dye chelates (for example, basic dye chelate, acid dye chelate, etc.), nitro pigments, nitroso pigments, aniline black, and the like.
[0015]
According to a preferred embodiment of the present invention, these pigments are preferably added to the ink as a pigment dispersion obtained by dispersing the pigment in an aqueous medium. As a preferable dispersant, a dispersant conventionally used for preparing a pigment dispersion, for example, a polymer dispersant or a surfactant can be used.
[0016]
The amount of the pigment added to the ink composition is preferably about 0.1 to 15% by weight, more preferably about 2 to 15% by weight.
[0017]
Aqueous solvent The aqueous solvent which is the basic solvent of the ink composition according to the present invention comprises an aqueous organic solvent and water.
[0018]
The aqueous organic solvent is preferably a low boiling point organic solvent, and preferable examples thereof include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, sec-butanol, tert-butanol, iso-butanol, Examples thereof include n-pentanol. A monohydric alcohol is particularly preferable. The low boiling point organic solvent has an effect of shortening the drying time of the ink.
[0019]
According to a preferred embodiment of the present invention, the aqueous solvent preferably further comprises a wetting agent composed of a high boiling point organic solvent. Preferred examples of the high boiling point organic solvent agent include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, thioglycol, hexylene glycol, glycerin, Polyhydric alcohols such as trimethylolethane and trimethylolpropane, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl Ether, triethylene glycol monobutyl ether Alkyl ethers of polyhydric alcohols such as urea, 2-pyrrolidone, N- methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, triethanolamine and the like.
[0020]
The amount of the wetting agent added is preferably 0.5 to 40% by weight of the ink, more preferably 2 to 20% by weight. The amount of the low-boiling organic solvent added is preferably 0.5 to 10% by weight of the ink, more preferably 1.5 to 6% by weight.
[0021]
The ink composition used in the present invention can contain a dispersant and a surfactant. Examples of surfactants include anionic surfactants, cationic surfactants, various surfactants such as amphoteric surfactants, alcohols such as methanol, ethanol, iso-propyl alcohol, ethylene glycol monomethyl ether, diethylene glycol Examples thereof include lower alkyl ethers of polyhydric alcohols such as monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monobutyl ether and dipropylene glycol monobutyl ether.
[0022]
In addition to the ink composition used in the present invention, a pH adjuster, a preservative, a fungicide, and the like may be added as necessary. For example, examples of the pH adjuster include potassium hydroxide, sodium hydroxide, and triethanolamine.
[0023]
Sugar According to a preferred embodiment of the present invention, the ink composition used in the present invention preferably contains a sugar. By adding this sugar, the color density can be further improved, and bleeding and uneven printing can be extremely reduced. Furthermore, color bleeding can be prevented at a higher level in a color image. Specific examples of saccharides include monosaccharides, disaccharides, oligosaccharides (including trisaccharides and tetrasaccharides) and polysaccharides, preferably glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, Examples include gulci seal, sorbit, maltose, cellobiose, lactose, sucrose, trehalose, maltotriose, and the like. Here, the polysaccharide means a saccharide in a broad sense, and is used to include a substance that exists widely in nature, such as alginic acid, α-cyclodextrin, and cellulose.
[0024]
The derivatives of these saccharides are represented by the reducing sugars of the saccharides described above (for example, sugar alcohols (general formula HOCH ₂ (CHOH) n CH ₂ OH (where n represents an integer of 2 to 5)). ), Oxidized sugars (eg, aldonic acid, uronic acid, etc.), amino acids, thio sugars, etc. Particularly preferred are sugar alcohols, and specific examples thereof include maltitol, sorbit and the like.
[0025]
The content of these saccharides is suitably 0.1 to 40% by weight, preferably 0.5 to 30% by weight of the ink composition.
[0026]
Epoxy group-containing compound According to a preferred embodiment of the present invention, the ink composition used in the present invention preferably comprises an epoxy group-containing compound. By adding the epoxy group-containing compound, it is possible to improve the abrasion resistance of the printed matter. In the present invention, the epoxy group-containing compound means a compound having at least two or more epoxy groups in the molecular structure, causing a cross-linking reaction involving the epoxy group and forming a resin (that is, having a high molecular weight). It shall be. Addition of this epoxy group-containing compound can impart good abrasion resistance and water resistance to the printed image.
[0027]
Examples of the epoxy group-containing compound used in the present invention include compounds having an epoxy group and further having a functional group capable of reacting with the epoxy group.
[0028]
Here, the functional group capable of reacting with an epoxy group means a group that reacts with an epoxy group to cause a cross-linking reaction, and examples thereof include a hydroxyl group, a carboxyl group, and a sulfonic acid group.
[0029]
In addition, since it is clear that it is not preferable that the epoxy group-containing compounds having a functional group capable of reacting with the epoxy group react in the ink composition, use of such an epoxy group-containing compound is avoided. Is preferred.
[0030]
Examples of the epoxy group-containing compound preferably used in the present invention include an epoxy group-containing resin emulsion.
[0031]
According to a preferred embodiment of the present invention, as the epoxy group-containing resin emulsion, the continuous phase is water, and the dispersed phase is represented by the following formulas (I) and (II):
[0032]
[Chemical 2]

(Where
R ¹ and R ³ independently represent H or CH ₃
R ² is an alkyl group in its structure (preferably C ₁ ~ ₂₁ alkyl), hydroxyl group, include a repeating unit represented by a group comprising one or more groups) selected from carboxyl and sulfonic acid groups And an epoxy group-containing acrylic resin emulsion comprising the copolymer. This resin is not limited depending on the mode of copolymerization, and can be, for example, a block copolymer, a random copolymer, or the like.
[0033]
In addition, the end of such a copolymer does not have an essential effect on the properties of the copolymer because it is a polymer, but in general, it will be a segment of a polymerization initiator. . Examples of such a section of the polymerization initiator include a section of a polymerization initiator such as ammonium persulfate and potassium persulfate, specifically -OSO ₃ H.
[0034]
Preferred examples of R ² include —OH, —COOH, —COO—R (wherein R represents a linear or branched alkyl group, preferably a C _1-12 alkyl group, and this alkyl group The one or more hydrogen atoms above may be substituted with a hydroxyl group, a phosphono group, or a sulfonic acid group), and an aryl group substituted with a sulfonic acid group (for example, a phenyl group or a tolyl group). Specific examples of the group represented by R ² include —OH, —COOH, —COOCH ₂ CH ₂ OH, —COOCH ₂ CH (CH ₃ ) OH, —COOCH ₂ CH ₂ PO (OH) ₂ , —C ₆ H. ₅ SO ₃ H, —COOCH ₂ CH ₂ SO ₃ H, —COOCH ₃ , —COOC ₂ H ₅ , —COOC ₄ H ₉ , —COOC ₆ H ₁₃ , —COO (CH ₂ ) ₁₁ CH, —COOCH ₂ CH ( CH ₃ ) CH ₂ C (CH ₃ ) _{3 and the} like. Here, the hydroxyl group, carboxyl group, or sulfonic acid group that may be contained in R ² is a functional group capable of reacting with an epoxy group.
[0035]
Commercially available resin emulsions can also be used. Examples thereof include ALMATEX Z116 (manufactured by Mitsui Toatsu Chemical Co., Ltd.), New Coat S-2170 and S-1080 (Shin Nakamura Chemical Co., Ltd.). Product), Vanatex # 952 and HG-9 (manufactured by Shin-Nakamura Chemical Co., Ltd.) and Pietex B-3 (manufactured by Shin-Nakamura Chemical Co., Ltd.).
[0036]
The content of the epoxy group-containing compound in the ink composition according to the present invention is preferably about 1 to 10% by weight, more preferably 1 to 5% by weight of the ink composition.
[0037]
The ink composition used in the present invention preferably comprises a resin emulsion as will be described later. When the epoxy group-containing compound is an epoxy group-containing resin emulsion, the epoxy group-containing compound is a resin emulsion. It also serves as an emulsion and does not have to contain a resin emulsion of another component. However, according to a preferred embodiment of the present invention, it is preferable to add a resin emulsion in addition to the epoxy group-containing resin emulsion.
[0038]
Resin emulsion Further , according to a preferred embodiment of the present invention, the ink composition used in the present invention preferably comprises a resin emulsion. In particular, the abrasion resistance of the printed matter can be improved by adding the resin emulsion. In the resin emulsion preferably used, the continuous phase is water, and the resin component of the dispersed phase does not contain an epoxy group. As described above, when the epoxy group-containing compound is an epoxy group-containing resin emulsion, the addition of this resin emulsion is not essential. Examples of such resin components include acrylic resins, vinyl acetate resins, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, butadiene resins, and styrene resins.
[0039]
Examples of commercially available resin emulsions include Microgel E-1002, E-5002 (styrene-acrylic resin emulsion, manufactured by Nippon Paint Co., Ltd.), and Boncoat 4001 (acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.). ) Boncoat 5454 (styrene-acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.), SAE-1014 (styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (acrylic resin emulsion, Seiden) Chemical Co., Ltd.).
[0040]
According to a preferred embodiment of the present invention, these resins are preferably polymers having both a hydrophilic part and a hydrophobic part. The particle size of these resin components is not particularly limited as long as an emulsion is formed, but is preferably about 150 nm or less, more preferably about 5 to 100 nm.
[0041]
These resin emulsions can be obtained by adding a surfactant and water to the polymer obtained by the polymerization reaction for emulsification, or by emulsion polymerization of the monomer in water in the presence of the surfactant. For example, an acrylic resin emulsion or a styrene-acrylic resin emulsion is obtained by emulsion polymerization of (meth) acrylic ester or styrene and (meth) acrylic ester in the presence of an emulsifier such as a surfactant. Can do. The mixing ratio of the resin component and the surfactant is usually preferably about 10: 1 to 5: 1. When the amount of the surfactant used is in the above range, better water resistance and penetrability of the ink can be obtained. The surfactant is not particularly limited, but preferred examples include anionic surfactants (for example, alkyl sulfates, alkyl allyl sulfonates, dialkyl succinates, alkyl naphthalene sulfonates), nonionic surfactants having an HLB of 10 or more (for example, polyoxy Ethylene alkyl ether, polyoxyethylene alkyl allyl ether, etc.), and these can be used alone or in admixture of two or more.
[0042]
Further, the ratio of the resin and water as the dispersed phase component is 60 to 400 parts by weight, preferably 100 to 200 parts by weight with respect to 100 parts by weight of the resin.
[0043]
The ink composition used in the present invention preferably contains a resin emulsion such that the resin component is 0.1 to 40% by weight of the ink composition, more preferably in the range of 1 to 25% by weight. .
[0044]
Ink jet recording method and recording apparatus According to a preferred embodiment of the present invention, the ink composition according to the present invention uses a recording head including a nozzle plate having a plating layer containing a fluorine-based polymer on its surface. The ink jet recording method is preferably used. By combining the above ink composition and such a recording head, it is possible to suppress the flight bending of the ink droplets to an extremely low level, and as a result, there is an advantage that stable printing is possible.
[0045]
The ink jet recording apparatus of FIG. 1 is an aspect in which an ink composition is stored in a tank and the ink composition is supplied to a recording head via an ink tube. That is, the recording head 1 and the ink tank 2 are communicated with each other through the ink tube 3.
[0046]
The recording head 1 is mounted on a carriage 4 and moved while being guided by a guide 9 by a timing belt 6 driven by a motor 5. On the other hand, the paper 7 as a recording medium is placed at a position facing the recording head 1 by the platen 8. In this embodiment, a cap 10 is provided. A suction pump 11 is connected to the cap 10 to perform a so-called cleaning operation. The sucked ink composition is stored in the waste ink tank 13 through the tube 12.
[0047]
An enlarged view of the nozzle plate of the recording head 1 is shown in FIG. The nozzle plate 101 is provided with a plurality of nozzles 102 from which an ink composition is ejected arranged in the vertical direction. Further, an enlarged cross-sectional view of the vicinity of the nozzle 102 is shown in FIG.
[0048]
In FIG. 3, the nozzle plate 101 includes a base material 103 and a plating layer 104 including a fluorine-based polymer provided thereon. The nozzle plate 101 is bonded to the nozzle base 106 via the adhesive layer 105, and an ink chamber 107 is formed. The ink chamber 107 is filled with the ink composition. For example, the meniscus is formed as indicated by M in the drawing. The ink composition in the ink chamber 107 receives pressure from an actuator (not shown) and is discharged as a droplet from the nozzle 102 in the direction of the arrow in the figure.
[0049]
The substrate 103 may be formed of metal, ceramics, silicon, glass, plastic, etc., preferably a single or nickel-phosphorous alloy such as titanium, chromium, iron, cobalt, nickel, copper, zinc, tin, gold, Tin-copper-phosphorus alloy (phosphor bronze), copper-zinc alloy, stainless steel, etc., polycarbonate, polysulfone, ABS resin (acrylonitrile / butadiene / styrene copolymer), polyethylene terephthalate, polyacetal, various photosensitive resins Formed by.
[0050]
The plating layer 104 containing the fluorine-based polymer on the surface of the base material 103 is formed by the eutectoid plating process as follows. First, the surface of the substrate is washed with an acid, and then the substrate is immersed in a solution in which particles of fluorine-based polymer are dispersed in an aqueous solution containing matrix metal ions. As a result, the fluorine-based polymer particles adhere to the surface of the base material 103 via the matrix metal ions, thereby forming a film. Thereafter, the coating is heated to a temperature not lower than the melting point of the fluoropolymer, for example, not lower than about 350 ° C., so that the uniform plating layer 104 can be formed. Here, examples of the fluorine-based polymer include polytetrafluoroethylene, polyperfluoroalkoxybutadiene, polyfluorovinylidene, polyfluorovinyl, and polydiperfluoroalkyl fumarate, and the following formulas (I) to (V): And a polymer represented by These polymers may be used alone or in combination.
[0051]
[Chemical 3]

(Wherein at least two of X ₁ , X ₂ , X ₃ , and X ₄ represent a fluorine atom or a perfluoroalkyl, the other represents an alkyl group, preferably a C _1-20 alkyl group, and R ₁ , R ₂ , R ₃ and R ₄ represent a hydrocarbon containing a hydrogen atom and a halogen atom)
[Formula 4]

(Where X1 represents COOC _m F _{2m + 1} and m represents ₁ to 20)
[Chemical formula 5]

(Where R represents an alkyl group, preferably a C _1-20 alkyl group)
[Chemical 6]

(Where R represents an alkyl group, preferably a C _1-20 alkyl group)
[0052]
The metal ions of the matrix metal are preferably nickel, copper, silver, zinc, and tin, and nickel, nickel-cobalt alloy, nickel-phosphorus alloy, and nickel-boron alloy have high surface hardness and wear resistance. It is excellent in property and is mentioned as a more preferable one.
[0053]
The plating layer 104 containing a fluoropolymer preferably has a thickness in the range of 1 to 10 μm in order to ensure good ink repellency and accuracy of the diameter of the ink ejection port. The eutectoid amount of the fluorine-based polymer in the plating layer 10 is preferably 60 vol% or less, particularly about 10 to 50 vol% in the plating layer.
[0054]
The eutectoid plating treatment may be performed by either an electroless method or an electrolysis method, but an electrolysis method that is less susceptible to the influence of ionic species in the ink composition and can form a highly durable plating layer is preferable. Further, when heating the fluorine-based temperature above the melting point of the polymer, to prevent warpage of the nozzle plate 101, 100 gf / cm ² or more, preferably, is preferably added to a pressure of 500 gf / cm ^2.
[0055]
【Example】
The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.
[0056]
Preparation <br/> following ink composition of the ink composition was prepared. That is, carbon black and a dispersing agent were mixed and dispersed in a sand mill (manufactured by Yasukawa Seisakusho) with glass beads (diameter 1.7 mm, 1.5 times the weight (weight) of the mixture) for 2 hours. Thereafter, the glass beads were removed, the other components were added, and the mixture was stirred at room temperature for 20 minutes. Filtration through a 5 μm membrane filter gave an ink for inkjet recording.
[0057]
Example 1
Carbon black MA7 (Mitsubishi Kasei Co., Ltd.) 5% by weight
Styrene-acrylic copolymer (dispersant) 1% by weight
Snowtex S (Colloidal silica, SiO ₂ content 30%, manufactured by Nissan Chemical)
10% by weight
Glycerin 10% by weight
2-pyrrolidone 2% by weight
Pure water remaining [0058]
Example 2
Carbon Black Raven1080 (Colombian Carbon Corporation) 5% by weight
Styrene-acrylic copolymer (dispersant) 1% by weight
Snowtex S (Colloidal silica, SiO ₂ content 20%, manufactured by Nissan Chemical)
0.5% by weight
Sucrose 0.7% by weight
Maltitol 6.3% by weight
Glycerin 10% by weight
2-pyrrolidone 2% by weight
Pure water remaining [0059]
Example 3
Carbon black MA7 (Mitsubishi Kasei Co., Ltd.) 5% by weight
Styrene-acrylic copolymer (dispersant) 1% by weight
Alumina sol-200 (Al ₂ O ₃ content 10%, manufactured by Nissan Chemical) 5% by weight
Boncoat 4001 5% by weight
(Acrylic resin emulsion, resin component 50%, MFT = 5 ° C., manufactured by Dainippon Ink Co., Ltd.)
Glycerin 10% by weight
2-pyrrolidone 2% by weight
Remaining pure water [0060]
Example 4
Carbon Black Raven1080 (Colombian Carbon Corporation) 5% by weight
Styrene-acrylic copolymer (dispersant) 1% by weight
Colloidal silica S 5% by weight Almatex Z116 3% by weight
(Epoxy group-containing acrylic resin emulsion, resin component 50%, manufactured by Mitsui Fukashika Chemical Co., Ltd.)
Glycerin 10% by weight
2-pyrrolidone 2% by weight
Pure water remaining [0061]
Example 5
Carbon Black Raven1080 (Colombian Carbon Corporation) 5% by weight
Styrene-acrylic copolymer (dispersant) 1% by weight
Glycerin 10% by weight
2-pyrrolidone 2% by weight
Remaining pure water [0062]
The performance of the ink composition over the evaluation test was evaluated as follows.
[0063]
Evaluation 1: Abrasion resistance Using an inkjet printer MJ-700V2C, printing was performed on XeroxP paper (manufactured by Xerox Co., Ltd.), and the printed matter was naturally dried for 24 hours. The printed matter was rubbed with a finger in an environment of 25 ° C. and 50 RH, and the presence or absence of generation of printing stains was visually observed. The results were as shown in the table. In the table,
○: When printing stains are not observed,
Δ: Printing smudge slightly occurs but character discrimination is possible ×: Character discrimination is impossible due to printing smudge
[0064]
Evaluation 2 : Fixability to dedicated media Using an inkjet printer MJ-700V2C, the ink is printed on a dedicated gloss film for MJ-700V2C (manufactured by Seiko Epson Corporation), and then the printed matter is naturally dried for 24 hours. The printed matter was rubbed with a finger in an environment of 25 ° C. and 50 RH, and the presence or absence of occurrence of printing stains and colorant peeling was visually observed. The results are as shown in the table. In the table,
◯: When printing stains and colorant peeling are not observed Δ: When printing stains occur slightly, but colorant peeling is not observed ×: Printing stains and colorant peeling occur both ]
Evaluation 3 : Printing unevenness Printing was performed on each of the following papers at 100% duty with an inkjet printer MJ-700V2C.
[0066]
Evaluation paper (1) Rcopy 6200 paper (Ricoh Co., Ltd.)
(2) Canon dry paper (manufactured by Canon Inc.)
Using Macbeth PCMII, OD values at arbitrary five points of the printed portion were measured, and the average was obtained.
[0067]
This procedure was repeated 5 times, and the maximum and minimum values of the five average values were determined. If this difference is less than 0.5, there is no practical problem, and more preferably less than 0.4. The results are as shown in the table. In the table,
○: OD value difference is less than 0.3 △: OD value difference is 0.3 or more and less than 0.4 ×: OD value difference is 0.4 or more
Evaluation 4: Discharge stability Filled with ink using an inkjet printer MJ-700V2C (Seiko Epson Corporation), continuously printed alphabet letters at room temperature, observed missing dots and ink scattering, generated 10 times or more I investigated the time to do. The results are as shown in the table. In the table,
A: Dot missing or ink scattering does not occur 10 times or more for 48 hours or more.
○: Dot missing or ink scattering occurs 10 times within 24 to 48 hours.
Δ: Dot missing or ink scattering occurs 10 times within 1 to 24 hours.
X: Dot missing or ink scattering occurs 10 times or more in 1 hour or less.
[Table 1]

[Brief description of the drawings]
FIG. 1 is a diagram showing an ink jet recording apparatus for carrying out a method according to the present invention. In this embodiment, a recording head and an ink tank are independent from each other, and an ink composition is supplied to the recording head through an ink tube .
FIG. 2 is an enlarged view of a nozzle plate of a recording head that is preferably used in combination with the ink composition according to the present invention. The nozzle plate 101 includes a plurality of nozzles 102 for discharging the ink composition arranged in the vertical direction. It will be.
3 is an enlarged cross-sectional view of the vicinity of a nozzle 102 provided on a nozzle plate 101. FIG. The nozzle plate 101 includes a base material 103 and a plating layer 104 including a fluorine-based polymer provided thereon.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Recording head 2 Ink tank 3 Ink tube 101 Nozzle plate 102 Nozzle 103 Base material 104 Plating layer containing fluoropolymer

Claims (11)

A pigment, an inorganic oxide colloid, an epoxy group-containing compound having a functional group capable of reacting with an epoxy group, an aqueous organic solvent, and water,
The inorganic oxide is anhydrous silicic acid or alumina;
An ink composition for ink jet recording, wherein the epoxy group-containing compound is an epoxy group-containing resin emulsion.   The ink composition for inkjet recording according to claim 1, wherein the inorganic oxide colloid is colloidal silica.   The ink composition for ink jet recording according to claim 1, further comprising a saccharide.   The ink composition for inkjet recording according to any one of claims 1 to 3, wherein the continuous phase is water and the resin component of the dispersed phase further contains a resin emulsion containing no epoxy group. The epoxy group-containing resin emulsion comprises a copolymer comprising repeating units represented by the following formulas (I) and (II), according to any one of claims 1 to 4. The ink composition for inkjet recording as described.

(Wherein R ¹ and R ³ independently represent H or CH ₃ , R ² represents —OH, —COOH, —COO—R (where R represents linear or branched alkyl, Further, one or more hydrogen atoms on the alkyl group may be substituted with a hydroxyl group, a phosphono group, or a sulfonic acid group), and an aryl group substituted with a sulfonic acid group).   The ink composition for inkjet recording according to any one of claims 1 to 5, which is used in an inkjet recording method using a recording head including a nozzle plate having a plating layer containing a fluorine-based polymer on a surface thereof.   The ink composition for ink-jet recording according to claim 6, wherein the plating layer containing a fluorine-based polymer is obtained by a eutectoid plating process.   An inkjet recording method for performing printing by discharging droplets of an ink composition from a recording head and attaching the droplets to a recording medium, wherein the ink composition is according to any one of claims 1 to 6. An ink jet recording method using an ink composition.   The ink jet recording method according to claim 8, wherein the surface of the nozzle plate of the recording head is a plating layer containing a fluorine-based polymer.   The ink jet recording method according to claim 9, wherein the plating layer containing a fluorine-based polymer is obtained by a eutectoid plating process.   The recorded matter recorded by the recording method as described in any one of Claims 8-10.

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