JP2004168793A - Ink composition, recording method and recorded image using the same, and ink set and ink head - Google Patents

Abstract

Provided are an ink composition having excellent ejection stability and capable of obtaining a high-quality recorded image when used in an ink jet recording method, a recording method and a recorded image using the same, an ink set and an ink head. .
The dynamic surface tension (σ ₁₀ ) when the bubble frequency is 10 Hz and the dynamic surface tension (σ ₁₀ ) when the bubble frequency is 1 Hz among dynamic surface tensions measured at a measurement temperature of 24 to 26 ° C. by the maximum bubble pressure method. The ink composition 60 is manufactured such that the difference d (= σ ₁₀ −σ ₁ ) from the dynamic surface tension (σ ₁ ) of the ink composition is 0 mN / m or more and 7 mN / m or less. A pressure is applied to the ink composition 60 supplied from the ink tank 50 of the ink head 1 to the ink chamber 40 by applying a voltage to the partition 12 made of a piezoelectric material. An image is recorded by discharging droplets and attaching the droplets onto a recording material.
[Selection diagram] Fig. 1

Description

【０１０４】
【化２】

【０１０５】
【化３】

【０１０６】
【化４】

【０１０７】
【化５】

【０１０８】
【化６】

【０１０９】
前記一般式（Ｉ）において、ｍは０〜３０の整数または小数を示し、ｎは０〜３０の整数または小数を示す。ただし、ｍとｎとの和（ｍ＋ｎ）は、０〜３０の整数または小数である。
【０１１０】
前記一般式（ＩＩ）において、ｋは１１〜１３の整数または小数を示し、ｌは３〜３０の整数または小数を示す。
【０１１１】
前記一般式（ＩＩＩ）において、ｈは０〜１１の整数または小数を示し、ｉは０〜１１の整数または小数を示し、ｊは３〜５０の整数または小数を示す。ただし、ｈとｉとの和（ｈ＋ｉ）は、９〜１１の整数または小数である。
【０１１２】
前記一般式（ＩＶ）において、ｗは０〜１１の整数または小数を示し、ｘは５〜９の整数または小数を示し、ｙは２．５〜５の整数または小数を示し、ｚは０〜９の整数または小数を示す。ただし、ｗとｚとの和（ｗ＋ｚ）は、９〜１１の整数または小数である。
【０１１３】
前記一般式（Ｖ）において、ｐは０〜７８の整数または小数を示し、ｑは２〜１５の整数または小数を示し、ｒは０〜１８の整数または小数を示す。
【０１１４】
前記一般式（ＶＩ）において、ｓは０〜３０の整数または小数を示し、ｔは０〜３０の整数または小数を示す。ただし、ｓとｔとの和（ｓ＋ｔ）は、０〜３０の整数または小数である。また、ｕは０〜１０の整数または小数を示し、ｖは０〜１０の整数または小数を示す。ただし、ｕとｖとの和（ｕ＋ｖ）は、０〜１０の整数または小数である。
【０１１５】
界面活性剤は、インク組成物中に臨界ミセル濃度以上含まれることが好ましい。界面活性剤を含有する溶液の表面張力は、臨界ミセル濃度までは界面活性剤の増加に伴って低下するけれども、臨界ミセル濃度以上ではほぼ一定である。したがって、前述のように界面活性剤を臨界ミセル濃度以上含有させることによって、界面活性剤の効果を充分に発揮させ、界面活性剤によって制御される前述の気泡周波数１０Ｈｚでの動的表面張力（σ_１０）および気泡周波数１Ｈｚでの動的表面張力（σ_１）をそれぞれほぼ一定の値にすることができるので、均一な性質を有するインク組成物を得ることができる。
【０１１６】
臨界ミセル濃度は、各界面活性剤で異なるけれども、非イオン系界面活性剤、アニオン系界面活性剤、カチオン系界面活性剤および両性界面活性剤のいずれの場合にも、２５℃において、０．００１重量％〜３重量％程度である。
【０１１７】
また本実施の形態のインク組成物は、色材に顔料を用いる場合には、バインダ樹脂を含有することが好ましい。バインダ樹脂を含有させることによって、被記録材上からの顔料の剥離を防ぐことができる。
【０１１８】
バインダ樹脂には、たとえば、ポリエステル樹脂、アクリル樹脂、スチレン−アクリル共重合体樹脂およびポリエステル−アクリル共重合体樹脂などからなる群から選ばれる１種または２種以上が用いられる。
【０１１９】
また本実施の形態のインク組成物は、色材、媒質、界面活性剤およびバインダ樹脂以外に、各種添加剤、たとえば防カビ剤、ｐＨ調整剤、キレート化剤、防錆剤または紫外線吸収剤などを含んでもよい。
【０１２０】
防カビ剤には、デヒドロ酢酸ナトリウム、安息香酸ナトリウムまたはソルビタン酸ナトリウムなどが好適に用いられる。
【０１２１】
ｐＨ調整剤には、トリエタノールアミン、水酸化ナトリウム、炭酸ナトリウム、硝酸ナトリウムまたは硝酸カリウムなどが好適に用いられる。
【０１２２】
少なくとも色材と媒質とを含有し、最大泡圧法によって測定温度２４℃以上２６℃以下で測定される動的表面張力のうち、気泡周波数が１０Ｈｚであるときの動的表面張力（σ_１０）と、気泡周波数が１Ｈｚであるときの動的表面張力（σ_１）との差ｄ（＝σ_１０−σ_１）が、前記式（１）を満足するインク組成物は、たとえば、０．５重量％〜１５重量％の色材と、３重量％〜７０重量％の有機溶媒と、２９重量％〜９５重量％の水と、０．００１重量％〜５重量％の界面活性剤とを含有させることによって得ることができる。
【０１２３】
図１は、本発明の第２の実施形態であるインクヘッド１の構成を簡略化して示す分解斜視図であり、図２は、図１に示すインクヘッド１を構成するヘッドプレート１０の構成の一部を拡大して示す斜視図である。なお、図１では、図２に示す駆動電極１３は、図が錯綜して理解が困難になるので記載を省略する。
【０１２４】
インクヘッド１は、圧電材料で形成される底壁部１１と複数の隔壁部１２とを有するヘッドプレート１０と、隔壁部１２の上面に設けられる天板２０と、複数の吐出口３１を備え隔壁部１２の一方の端部に設けられるノズルプレート３０と、隔壁部１２の他方の端部に設けられる図示しない背面板と、天板２０の上部に設けられ開口部５１を有するインクタンク５０とを含んで構成される。複数の隔壁部１２は、底壁部１１上に所定の間隔で平行に配置されており、複数の隔壁部１２と底壁部１１と天板２０とノズルプレート３０と図示しない背面板とによって複数のインク室４０が形成されている。天板２０には、各インク室４０に連通する共通インク供給路２１と、共通インク供給路２１とインクタンク５０の開口部５１とを連結するインク供給管２２とが形成される。インクタンク５０には実施の第１形態のインク組成物６０が貯留されており、このインク組成物６０は共通インク供給路２１を介して各インク室４０に供給される。
【０１２５】
また図２に示すように、ヘッドプレート１０の底壁部１１および複数の隔壁部１２のインク室４０に臨む表面には、複数の隔壁部１２に電圧を印加する駆動電極１３が形成される。また複数の隔壁部１２を形成する圧電材料は、矢符７０の方向に分極しており、複数の隔壁部１２は圧電素子として機能する。
【０１２６】
このように構成されるインクヘッド１は、圧電素子である複数の隔壁部１２に印加される電圧に応じて、吐出口３１からインク組成物６０の液滴を吐出させることのできるピエゾ方式のインクヘッドである。
【０１２７】
インクヘッド１において、インク室４０からインク組成物６０を吐出させる際の動作原理について説明する。図３は、図１に示すインクヘッド１をインク室４０の延長方向から見た断面図である。ここでは、インク室４０ｂからインク組成物６０を吐出させる場合の動作について説明する。
【０１２８】
インク室４０ｂを構成する隔壁部１２ａおよび１２ｂに電圧が印加されていないとき、すなわちインク室４０ｂの駆動電極１３ｂとインク室４０ｂに隣接するインク室４０ａの駆動電極１３ａとの間、およびインク室４０ｂの駆動電極１３ｂとインク室４０ｂに隣接するインク室４０ｃの駆動電極１３ｃとの間に電位差が生じていないとき、インク室４０ｂは、毛管作用によってインクタンク５０から供給されるインク組成物６０で充填された状態になっている。同様に、インク室４０ａおよび４０ｃもインク組成物６０で充填された状態になっている。
【０１２９】
駆動電極１３ａおよび駆動電極１３ｃに電圧が印加されると、駆動電極１３ｂと駆動電極１３ａとの間、および駆動電極１３ｂと駆動電極１３ｃとの間に電位差が生じ、インク室４０ｂを構成する隔壁部１２ａおよび１２ｂに電圧が印加される。この電圧によって、隔壁部１２ａおよび１２ｂにそれぞれ矢符７１および７２の方向の電界が発生し、この電界の作用によって、インク室４０ｂを構成する隔壁部１２ａおよび１２ｂにひずみが生じ、インク室４０ｂ側に凸になるように変形する。これによって、圧力波が発生し、インク室４０ｂ内に充填されているインク組成物６０に大きな圧力がかかり、インク組成物６０の液滴が前述の図１に示す吐出口３１から吐出する。
【０１３０】
駆動電極１３ａおよび駆動電極１３ｃへの電圧の印加を止めると、隔壁部１２ａおよび１２ｂの形状が元に戻ってインク室４０ｂの体積が元に戻り、復元された体積分のインク組成物６０が前述の図１に示す共通インク供給路２１を介してインクタンク５０から供給され、インク室４０ｂは、インク組成物６０が充填された初期の状態に戻る。
【０１３１】
本実施の形態のインクヘッド１では、前述のようにインクタンク５０は実施の第１形態のインク組成物６０を貯留し、このインク組成物６０がインク室４０に供給されて吐出口３１から液滴として吐出するので、安定して吐出口３１からインク組成物６０の液滴を吐出させることができる。このようなインクヘッドを用いれば、信頼性の高いピエゾ方式のインクジェット記録装置を実現することができ、高品質の記録画像を安定して得ることができる。
【０１３２】
以上に述べたように、本実施の形態では、インク室４０を構成する隔壁部１２を圧電材料で形成し、圧電素子として機能させるけれども、これに限定されることなく、インク室を構成する隔壁を圧電材料以外の材料で形成し、隔壁の内方または外方に圧電素子を設けてもよい。
【０１３３】
図４は、本発明の第３の実施形態であるインクヘッド２の構成を簡略化して示す分解斜視図であり、図５は、図４に示すインクヘッド２の構成の一部を示す平面図である。なお、図５では、図４に示す天板２０およびインクタンク５０は、図が錯綜して理解が困難になるので、記載を省略する。本実施の形態のインクヘッド２は、実施の第２形態のインクヘッド１と類似し、対応する部分については同一の参照符号を付して説明を省略する。
【０１３４】
注目すべきは、ヘッドプレート１００が、基板１０１と、基板１０１上に所定の間隔で平行に配置される複数の隔壁１０２と、基板１０１のインク室４０に臨む表面上に設けられる発熱体であるヒータ１０３と、ヒータ１０３に電圧を印加する駆動電極１０４および１０５とを含んで構成されることである。
【０１３５】
このように構成されるインクヘッド２は、発熱体であるヒータ１０３に印加される電圧に応じて、吐出口３１からインク組成物６０の液滴を吐出させることのできるサーマルインクジェット方式のインクヘッドである。
【０１３６】
インクヘッド２において、インク室４０からインク組成物６０を吐出させる際の動作原理について説明する。図６は、インク室４０からインク組成物６０の液滴６１が吐出する様子を模式的に示す断面図である。図６では、図５に示すインクヘッド２の切断面線Ｉ−Ｉにおける断面構成を示す。
【０１３７】
ヒータ１０３に電圧が印加されていないとき、実施の第２形態のインクヘッド１において隔壁部１２に電圧が印加されていないときと同様に、インク室４０はインク組成物６０が充填された状態になっている。
【０１３８】
駆動電極１０４および１０５によってヒータ１０３に電圧が印加されると、ヒータ１０３が発熱し、インク室４０内に充填されているインク組成物６０が加熱されて、気泡６２が発生する。これによって、圧力波が発生し、インク室４０内に充填されているインク組成物６０に大きな圧力がかかり、インク組成物６０の液滴６１が吐出口３１から吐出する。
【０１３９】
ヒータ１０３への電圧の印加を止めると、インク室４０内のインク組成物６０が冷却されて気泡６２が消滅し、復元された体積分のインク組成物６０が前述の図４に示す共通インク供給路２１を介してインクタンク５０から供給され、インク室４０は、インク組成物６０が充填された初期の状態に戻る。
【０１４０】
本実施の形態のインクヘッド２では、前述の実施の第２形態のインクヘッド１と同様に、インクタンク５０は実施の第１形態のインク組成物６０を貯留し、このインク組成物６０がインク室４０に供給されて吐出口３１から液滴６１として吐出するので、安定して吐出口３１からインク組成物６０の液滴６１を吐出させることができる。このようなインクヘッドを用いれば、信頼性の高いサーマルインクジェット方式のインクジェット記録装置を実現することができ、高品質の記録画像を安定して得ることができる。
【０１４１】
【実施例】
以下、本発明について、実施例を用いてさらに詳細に説明するけれども、本発明は、これに限定されるものではない。なお、本実施例では、画像を記録することを印刷または印字と呼ぶことがある。
【０１４２】
＜インク組成物＞
インク組成物の作製に際し、色材、有機溶媒および界面活性剤の種類および含有量、ならびにバインダ樹脂および水の含有量を表１に示すように変化させることによって、前述の気泡周波数１０Ｈｚでの動的表面張力（σ_１０）と気泡周波数１Ｈｚでの動的表面張力（σ_１）との差ｄ（＝σ_１０−σ_１）が前記式（１）を満足する実施例１〜７のインク組成物と、ｄが前記式（１）を満足しない比較例１〜４のインク組成物とを得た。表１において、各欄の値の単位は重量部であり、実施例１〜７および比較例１〜４の各インク組成物の合計量はそれぞれ１００重量部である。また表１において、ＴＥＧＢＥは、トリエチレングリコールモノブチルエーテル（Ｔｒｉｅｔｈｙｌｅｎｅ ｇｌｙｃｏｌ ｍｏｎｏｂｕｔｙｌ ｅｔｈｅｒ）を表し、ＰＥＧ４００は、分子量が４００のポリエチレングリコール（Ｐｏｌｙｅｔｈｙｌｅｎｅ ｇｌｙｃｏｌ）を表し、一般式（Ｉ）は、前記一般式（Ｉ）で示される界面活性剤を表し、一般式（ＩＩ）は、前記一般式（ＩＩ）で示される界面活性剤を表し、一般式（ＩＩＩ）は、前記一般式（ＩＩＩ）で示される界面活性剤を表し、一般式（ＩＶ）は、前記一般式（ＩＶ）で示される界面活性剤を表し、一般式（Ｖ）は、前記一般式（Ｖ）で示される界面活性剤を表し、フッ素系界面活性剤１は、下記構造式（ＶＩＩ）で示される界面活性剤を表し、フッ素系界面活性剤２は、下記構造式（ＶＩＩＩ）で示される界面活性剤を表す。なお、インク組成物中の界面活性剤の濃度は、実施例１〜７および比較例１〜３では臨界ミセル濃度以上であり、比較例４では臨界ミセル濃度未満である。
【０１４３】
【化７】

【０１４４】
【化８】

【０１４５】
実施例１〜７および比較例１〜４の各インク組成物の動的表面張力の測定は、表面張力計（協和界面科学株式会社製：ＢＰ−４）を用いて、気泡周波数０．５Ｈｚ〜３５Ｈｚにおいて行った。
【０１４６】
表２に、実施例１〜７および比較例１〜４の各インク組成物の気泡周波数１０Ｈｚでの動的表面張力（σ_１０）および気泡周波数１Ｈｚでの動的表面張力（σ_１）の測定値（ｍＮ／ｍ）、σ_１０とσ_１との差ｄ（＝σ_１０−σ_１）の値（ｍＮ／ｍ）、ならびにそのときの測定温度（℃）を示す。
【０１４７】
【表１】

【０１４８】
【表２】

【０１４９】
得られた実施例１〜７および比較例１〜４の各インク組成物について、インクジェット記録法に用いた場合の吐出安定性および得られる記録画像の画質の評価を以下のように行った。
【０１５０】
（吐出安定性）
前述の図１に示すインクヘッド１を装着できるように市販のインクジェット記録装置（シャープ株式会社製：ＡＪ２０００）を改造して得られたインクジェット記録装置のインクタンクに、得られた実施例１〜７および比較例１〜４のインク組成物をそれぞれ充填し、印刷濃度を５％として毎分Ａ４判用紙７枚の印刷速度で、シャープ株式会社製の複写機用普通紙（品番：ＳＦ４ＡＭ３）上に連続的に印刷を行った。試験ではインクタンクが空になった時点でインク組成物を再充填し、ノズルからインク組成物の液滴が吐出せず印刷することができなくなるまで印刷を行い、その時点までに完全に印刷できた枚数を印刷可能枚数として求め、吐出安定性の評価指標とした。印刷可能枚数が２００枚を超える場合を良（○）とし、１５０〜２００枚の場合を可（△）とし、１５０枚未満の場合を不良（×）とした。
【０１５１】
（画質）
前述の図１に示すインクヘッド１を装着できるように市販のインクジェット記録装置（シャープ株式会社製：ＡＪ２０００）を改造して得られたインクジェット記録装置のインクタンクに、得られた実施例１〜７および比較例１〜４のインク組成物をそれぞれ充填し、シャープ株式会社製の複写機用普通紙（品番：ＳＦ４ＡＭ３）上に特定のパターンを印刷し、評価用画像を形成した。前記評価用画像を１日放置した後、設定したパターンの線幅を１００として、これに対する各評価用画像のパターンの線幅の相対値を求め、画質の評価指標とした。線幅の相対値が１５０未満であり滲みがほとんどない場合を良（○）とし、１５０以上２５０以下であり若干の滲みがある場合を可（△）とし、２５０を超え滲みが多い場合を不良（×）とした。
以上の評価結果を表３に示す。
【０１５２】
【表３】

【０１５３】
気泡周波数１０Ｈｚでの動的表面張力（σ_１０）と気泡周波数１Ｈｚでの動的表面張力（σ_１）との差ｄ（＝σ_１０−σ_１）が前記式（１）を満足する実施例１〜７のインク組成物では、吐出安定性および画質のいずれもが良であった。一方、ｄが７より大きく前記式（１）を大きい方に外れる比較例１〜４のインク組成物では、吐出安定性および画質のいずれもが不良または可であった。
【０１５４】
以上のように、気泡周波数１０Ｈｚでの動的表面張力（σ_１０）と気泡周波数１Ｈｚでの動的表面張力（σ_１）との差ｄ（＝σ_１０−σ_１）が前記式（１）を満足するように設計することによって、インクジェット記録法に用いた場合、吐出安定性に優れるとともに、被記録材上における滲みを抑え高品質の記録画像を得ることが可能なインク組成物を得ることができた。
【０１５５】
＜インクセット＞
実施例２〜６および比較例１〜３のインク組成物を、表４に示すようにシアン、マゼンタおよびイエローのインク組成物として組合せることによって、Ｃ．Ｉ．ピグメントブルー１５：３および１５：４のうちの少なくとも一方の顔料を含有するシアンのインク組成物と、Ｃ．Ｉ．ピグメントレッド１２２，２０９およびＣ．Ｉ．ピグメントヴァイオレット１９からなる群から選ばれる少なくとも１つの顔料を含有するマゼンタのインク組成物と、Ｃ．Ｉ．ピグメントイエロー７４，１３８，１５０および１８０からなる群から選ばれる少なくとも１つの顔料を含有するイエローのインク組成物とを含む実施例インクセット１と、シアン、マゼンタおよびイエローのインク組成物のうちのいずれかが前述の顔料と異なる顔料を含有する比較例インクセット１〜３と、シアン、マゼンタおよびイエローのインク組成物のすべてが前述の顔料と異なる顔料を含有する比較例インクセット４とを得た。
【０１５６】
【表４】

【０１５７】
得られた実施例インクセット１および比較例インクセット１〜４をそれぞれ用い、市販のインクジェット記録装置（シャープ株式会社製：ＡＪ２０００）を改造して得られたインクジェット記録装置を使用し、シャープ株式会社製の光沢紙（品番：ＡＪ−Ｋ４ＡＧ）上に、シアン、マゼンタおよびイエローの各インク組成物の印字率を１：１：１として印刷することによって黒色画像を形成した。また、ブラックのインク組成物である実施例７のインク組成物を用い、同一の画像を形成した。
【０１５８】
得られた各黒色画像について、分光測色計（Ｘ−Ｒｉｔｅ社製：Ｘ−Ｒｉｔｅ９３８）を用い、Ｌ^＊ａ^＊ｂ^＊表色系（ＣＩＥ：１９７６）における明度指数Ｌ^＊およびクロマチックネス指数ａ^＊，ｂ^＊を測定した。
【０１５９】
試験結果の評価は、以下のように行った。実施例７のインク組成物を用いて形成された黒色画像のクロマチックネス指数ａ^＊をＡ１、ｂ^＊をＢ２とし、実施例インクセット１および比較例インクセット１〜４をそれぞれ用いて形成された黒色画像のクロマチックネス指数ａ^＊をＡ２、ｂ^＊をＢ２として、下記式（３）で示されるΔａ^＊ｂ^＊の値を求め、黒色再現性の評価指標とした。
Δａ^＊ｂ^＊＝｛（Ａ１−Ａ２）^２＋（Ｂ１−Ｂ２）^２｝^１／２ …（３）
Δａ^＊ｂ^＊の値が、２０以下（Δａ^＊ｂ^＊≦２０）である場合を良（○）とし、２０を超える（Δａ^＊ｂ^＊＞２０）場合を不良（×）とした。評価結果を表５に示す。
【０１６０】
【表５】

【０１６１】
表５から、実施例インクセット１に含まれる３種類のインク組成物を重ね合わせて得られる黒色画像は、比較例インクセット１〜４にそれぞれ含まれる３種類のインク組成物を重ね合わせて得られる黒色画像に比べ、実施例７のインク組成物を用いて形成された黒色画像に近い濃い濃度の黒色画像であることが判った。すなわち、実施例インクセット１は、比較例インクセット１〜４に比べ、黒色再現性が良好であり、カラーバランスに優れることが判った。
【０１６２】
以上のように、Ｃ．Ｉ．ピグメントブルー１５：３および１５：４のうちの少なくとも一方の顔料を含有するシアンのインク組成物と、Ｃ．Ｉ．ピグメントレッド１２２，２０９およびＣ．Ｉ．ピグメントヴァイオレット１９からなる群から選ばれる少なくとも１つの顔料を含有するマゼンタのインク組成物と、Ｃ．Ｉ．ピグメントイエロー７４，１３８，１５０および１８０からなる群から選ばれる少なくとも１つの顔料を含有するイエローのインク組成物とを組合せることによって、カラーバランスに優れるインクセットを得ることができた。
【０１６３】
【発明の効果】
以上のように本発明によれば、最大泡圧法によって測定温度２４〜２６℃で測定される気泡周波数１０Ｈｚでの動的表面張力と気泡周波数１Ｈｚでの動的表面張力との差が、ある一定の範囲内になるようにインク組成物を設計するので、インクジェット記録法に用いた場合、吐出安定性に優れるとともに、被記録材上における滲みを抑え高品質の記録画像を得ることが可能なインク組成物を得ることができる。
【０１６４】
また本発明によれば、気泡周波数１０Ｈｚでの動的表面張力および気泡周波数１Ｈｚでの動的表面張力が好適な範囲に選択されるので、インクジェット記録法に用いた場合、吐出安定性に優れるとともに、被記録材上における滲みを抑え高品質の記録画像を得ることが可能なインク組成物を得ることができる。
【０１６５】
また本発明によれば、界面活性剤をさらに含有するので、気泡周波数１０Ｈｚでの動的表面張力および気泡周波数１Ｈｚでの動的表面張力を含むインク組成物の動的表面張力を容易に制御することができる。
【０１６６】
また本発明によれば、媒質は水を含むので、吸収性の被記録材上における滲みを抑え、乾燥性を向上させることができる。
【０１６７】
また本発明によれば、媒質は、蒸気圧の低いグリコールエーテル類および多価アルコール類のうちの少なくとも一方を含むので、湿潤効果が得られ、吐出安定性を向上させることができる。
【０１６８】
また本発明によれば、色材は染料を含むので、目詰まりの発生を抑え、吐出安定性を向上させることができる。
【０１６９】
また本発明によれば、色材は顔料を含むので、耐光性および耐水性に優れる記録画像を得ることができる。
【０１７０】
また本発明によれば、色材は親水基を有する顔料を含むので、目詰まりの発生を抑えることができ、吐出安定性を損なうことなく、耐光性および耐水性に優れる記録画像を得ることが可能なインク組成物を得ることができる。
【０１７１】
また本発明によれば、界面活性剤は、共存する電解質の影響を受けにくい非イオン系界面活性剤を含むので、インク組成物に電解質が添加されるか否かに関わらず、気泡周波数１０Ｈｚでの動的表面張力と気泡周波数１Ｈｚでの動的表面張力との差を、ある一定の範囲内にすることができる。
【０１７２】
また本発明によれば、界面活性剤は臨界ミセル濃度以上含まれるので、界面活性剤の効果を充分に発揮させ、界面活性剤によって制御される気泡周波数１０Ｈｚでの動的表面張力および気泡周波数１Ｈｚでの動的表面張力をそれぞれほぼ一定の値にすることができ、均一な性質を有するインク組成物を得ることができる。
【０１７３】
また本発明によれば、シアンの発色性に優れる記録画像を実現可能なインク組成物を得ることができる。
【０１７４】
また本発明によれば、マゼンタの発色性に優れる記録画像を実現可能なインク組成物を得ることができる。
【０１７５】
また本発明によれば、イエローの発色性に優れる記録画像を実現可能なインク組成物を得ることができる。
【０１７６】
また本発明によれば、ブラックの発色性に優れる記録画像を実現可能なインク組成物を得ることができる。
【０１７７】
また本発明によれば、高品質の記録画像を安定して提供することができる。
また本発明によれば、安定した吐出が可能であるとともに、高品質の記録画像を安定して提供することができる。
【０１７８】
また本発明によれば、様々な色を表現することができるので、発色性に優れるフルカラーの記録画像を提供することができる。
【０１７９】
また本発明によれば、高品質の記録画像を得ることができる。
また本発明によれば、カラーバランスに優れるインクセットを得ることができるので、様々な色を表現することができ、発色性に優れるフルカラーの記録画像を実現することができる。
【０１８０】
また本発明によれば、圧電素子に印加される電圧に応じて、吐出口からインク組成物の液滴を吐出させることのできるピエゾ方式のインクヘッドにおいて、安定して吐出口からインク組成物の液滴を吐出させることができる。
【０１８１】
また本発明によれば、発熱体に印加される電圧に応じて、吐出口からインク組成物の液滴を吐出させることのできるサーマルインクジェット方式のインクヘッドにおいて、安定して吐出口からインク組成物の液滴を吐出させることができる。
【０１８２】
また本発明によれば、記録画像は、安定してインク組成物の液滴を吐出させることのできるピエゾ方式のインクヘッドによって吐出されるインク組成物の液滴が、被記録材上に付着されることによって記録されるので、高品質の記録画像を安定して得ることができる。
【０１８３】
また本発明によれば、記録画像は、安定してインク組成物の液滴を吐出させることのできるサーマルインクジェット方式のインクヘッドによって吐出されるインク組成物の液滴が、被記録材上に付着されることによって記録されるので、高品質の記録画像を安定して得ることができる。
【図面の簡単な説明】
【図１】本発明の第２の実施形態であるインクヘッド１の構成を簡略化して示す分解斜視図である。
【図２】図１に示すインクヘッド１を構成するヘッドプレート１０の構成の一部を拡大して示す斜視図である。
【図３】図１に示すインクヘッド１をインク室４０の延長方向から見た断面図である。
【図４】本発明の第３の実施形態であるインクヘッド２の構成を簡略化して示す分解斜視図である。
【図５】図４に示すインクヘッド２の構成の一部を示す平面図である。
【図６】インク室４０からインク組成物６０の液滴６１が吐出する様子を模式的に示す断面図である。
【符号の説明】
１，２ インクヘッド
１０ ヘッドプレート
１１ 底壁部
１２，１２ａ，１２ｂ 隔壁部
１３，１３ａ，１３ｂ，１３ｃ 駆動電極
２０ 天板
２１ 共通インク供給路
２２ インク供給管
３０ ノズルプレート
３１ 吐出口
４０，４０ａ，４０ｂ，４０ｃ インク室
５０ インクタンク
５１ 開口部
６０ インク組成物
６１ 液滴
６２ 気泡
１００ ヘッドプレート
１０１ 基板
１０２ 隔壁
１０３ ヒータ
１０４，１０５ 駆動電極[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink composition suitably used in an ink jet recording method, a recording method and a recorded image using the same, an ink set and an ink head.
[0002]
[Prior art]
In the ink jet recording method, droplets of an ink composition (hereinafter, also simply referred to as “ink”) are ejected and fly using mechanical energy or thermal energy, and the droplets are deposited on a recording material such as paper. This is a method of recording an image.
[0003]
2. Description of the Related Art Conventionally, characteristics of ink used in an ink jet recording method (hereinafter, also simply referred to as “ink for ink jet”) are shown by physical property values such as surface tension and viscosity. By defining these physical property values, the drying property of the ink is adjusted and the quality of the formed image is improved.
[0004]
For example, an ink jet recording method using ink droplets defined by the product of the Weber number including surface tension as a factor and the Reynolds number including viscosity as a factor has been proposed. By setting the product of the Weber number and the Reynolds number within a specific range, a high-quality image is realized (see Patent Document 1). Further, an inkjet recording method using an ink having a surface tension in a specific range has been proposed (see Patent Document 2).
[0005]
The surface tensions treated by the techniques described in Patent Documents 1 and 2 are surface tensions when the liquid surface reaches an equilibrium state, that is, static surface tensions. The surface tension generally used as an index of the characteristics of the ink for ink jet is also a static surface tension (for example, see Non-Patent Document 1). As described above, the characteristics of the inkjet ink are often indicated by the static surface tension among the surface tensions.
[0006]
However, it is difficult to sufficiently exhibit the characteristics of the ink-jet ink with a static surface tension.
[0007]
In an ink jet recording apparatus that records an image using an ink jet recording method, an ink chamber in an ink head is filled with ink, and ink droplets are continuously ejected and ejected from ejection ports provided at the tip of the ink chamber. Then, an image is recorded by being attached to a recording material. When the ink is continuously ejected, a new surface of the ink, that is, a new meniscus is formed at the same time as the ink droplet is ejected at the ejection port, so the surface tension of the ink is such that a new surface is formed at the ejection port. It differs at the start, immediately before ejection, at the moment of ejection, at the time of flight, at the moment of landing on a recording material, and when it permeates a recording material such as paper. That is, the surface tension of the ink is the surface tension in a state of slow movement such as when a new surface starts to be formed in the ejection port or when the ink penetrates a recording material such as paper, and the surface tension of the ink at the moment of ejection. It changes momentarily between the surface tension in a fast moving state. Therefore, in order to sufficiently exhibit the characteristics of the ink-jet ink, it is necessary to use dynamic surface tension, which is the surface tension during the time when the liquid surface reaches an equilibrium state.
[0008]
The importance of dynamic surface tension has been described in many publications. For example, Schwartz, J evaluates the static surface tension and the dynamic surface tension of a water-based paint, and the dynamic surface tension is an important factor in forming a film with the water-based paint. It shows that it is effective for forming a uniform and excellent coating film (see Non-Patent Document 2).
[0009]
See also Medina, S.A. W. And Sutovich, M .; N. Discusses the importance of dynamic surface tension in high-speed printing, and the static surface tension, which is the surface tension when the liquid surface reaches equilibrium, becomes slower as it penetrates paper etc. Although this is effective as an index indicating the properties of a certain ink, it suggests that it is not effective as an index indicating the properties of the ink in a particularly fast-moving state such as in high-speed printing. On the other hand, the dynamic surface tension is determined by the fact that the surfactant contained in the ink is formed between the newly formed surface of the ink that is successively newly formed at the ejection port or the ink droplets that are successively attached to the recording material and the recording material. This suggests that it is an indicator of the ability to migrate to the interface. That is, since the surfactant lowers the surface tension of the ink by adsorbing on the newly formed surface of the ink or the interface between the ink droplet and the recording material, the surfactant moves to the newly formed surface of the ink or the interface between the ink droplet and the recording material. The higher the ability to perform, the higher the effect of lowering the surface tension of the ink in a fast moving state, and the lower the dynamic surface tension of the ink (see Non-Patent Document 3).
[0010]
Further, there has been proposed an ink composition suitable for an ink jet recording method in which the relationship between dynamic surface tension and viscosity is defined, and a recording method using the same. According to this technique, it is shown that the ink composition can obtain good printing characteristics within a range satisfying the condition of [dynamic surface tension (dyne / cm) of 0 msec in life] + [viscosity (cP)] = 42 to 49. (See Patent Document 3).
[0011]
[Patent Document 1]
Japanese Patent No. 2968010
[Patent Document 2]
JP-B-63-65034
[Patent Document 3]
Patent No. 2516218
[Non-patent document 1]
Akio Kinoshita, "Practical technology of special function inks", first edition of popular edition, CMC Corporation, November 15, 1999, p. 4
[Non-patent document 2]
Schwartz, J .; , "The Importance of Low Dynamic Surface Tension in
Waterborn Coatings ", Journal of Coatings Technology, USA, vol. 64, no. 812 (1992), p. 65-74
[Non-Patent Document 3]
Medina, S .; W. and Sutovich, M .; N. , "Using Surfactants to Formulate VOC Combinant Waterbased Inks", American Ink Maker, USA, vol. 72, no. 2 (1994), p. 32-38
[0012]
[Problems to be solved by the invention]
However, in the technology described in Patent Document 3, although the dynamic surface tension is defined by using a conditional expression in which the value of the dynamic surface tension and the value of the viscosity are added, the dynamic surface tension and the viscosity are expressed in units. Are different, that is, the dimensions are different, so the value itself of the above conditional expression has no meaning at all.
[0013]
This technique also shows that the surfactant does not contribute to the reduction of the dynamic surface tension. However, it is known that a surfactant generally greatly contributes to the wettability of the ink for an ink jet with respect to the inner wall of an ink chamber and the properties on a recording material. It is also important for control. For example, Schwartz, J., in the aforementioned Non-Patent Document 2, used several surfactants to change the static surface tension and the dynamic surface tension, and evaluated the effects of the surfactants on the film formation. It is shown that lowering the target surface tension is effective for reducing shrinkage of the coating film, generation of craters in the coating film, and reduction of air bubble entrapment.
[0014]
Further, the dynamic surface tension defined by this technique is only the dynamic surface tension of 0 msec in a particularly fast moving state, and the dynamic surface tension in a slow moving state is not defined. As described above, in the ink-jet recording method, the surface tension of the ink changes every moment between the surface tension in a slow-moving state and the surface tension in a fast-moving state. For this purpose, both dynamic surface tension in a fast moving state and dynamic surface tension in a slow moving state are required.
[0015]
An object of the present invention is to provide a high-quality ink with excellent ejection stability when used in an inkjet recording method by defining the relationship between the dynamic surface tension in a fast-moving state and the dynamic surface tension in a slow-moving state. An object of the present invention is to provide an ink composition capable of obtaining a recorded image, a recording method and a recorded image using the same, an ink set and an ink head.
[0016]
[Means for Solving the Problems]
The present invention provides an ink composition containing at least a coloring material and a medium,
Among the dynamic surface tensions measured at a measurement temperature of 24 to 26 ° C. by the maximum bubble pressure method, the dynamic surface tension (σ) when the bubble frequency is 10 Hz ₁₀ ) And the dynamic surface tension when the bubble frequency is 1 Hz (σ ₁ D) (= σ) ₁₀ −σ ₁ ) Is an ink composition characterized by satisfying the following formula (1).
0 mN / m ≦ d ≦ 7 mN / m (1)
[0017]
According to the present invention, the dynamic surface tension (σ) when the bubble frequency is 10 Hz among the dynamic surface tensions measured at a measurement temperature of 24 ° C. or more and 26 ° C. or less by the maximum bubble pressure method. ₁₀ ) And the dynamic surface tension when the bubble frequency is 1 Hz (σ ₁ D) (= σ) ₁₀ −σ ₁ ) Is designed to fall within a certain range. In an ink jet recording apparatus that records an image using an ink jet recording method, when droplets of the ink composition are continuously ejected, the ejection port provided at the tip of the ink chamber in the ink head regenerates the ink composition. Since the surface is constantly generated, the movement of the ink composition is fast, and the influence of the dynamic surface tension at a high frequency of about 10 Hz, which corresponds to the dynamic surface tension in the fast-moving state, is large. On the other hand, in the ink chamber, after the ink composition is ejected, the reduced volume of the ink composition is ejected and supplied from the ink tank by capillary action, so that the movement of the ink composition is slow and the ink composition is slow. The effect of the dynamic surface tension at a low frequency of about 1 Hz corresponding to the dynamic surface tension in the above is large. That is, during ejection, both the dynamic surface tension at a high frequency and the dynamic surface tension at a low frequency are affected. It is necessary to balance the dynamic surface tension at low frequencies with the dynamic surface tension at low frequencies. In addition, the movement of the ink composition when recording an image by attaching a droplet of the ink composition onto a recording material is fast at the moment when the droplet lands on the recording material, but gradually slows down thereafter, In the case of an absorbent recording material, the ink composition slowly penetrates into the recording material. That is, the dynamic surface tension of the ink composition changes from a dynamic surface tension in a fast-moving state to a dynamic surface tension in a slow-moving state, so that the dynamic surface tension at a high frequency and the dynamic surface tension at a low frequency change. If the difference from the target surface tension is large, it takes time until the ink composition dries on the recording material, and bleeding occurs. In addition, it penetrates too much to cause strikethrough. Therefore, as described above, the dynamic surface tension at the bubble frequency of 10 Hz (σ ₁₀ ) And the dynamic surface tension at the bubble frequency of 1 Hz (σ ₁ D) (= σ) ₁₀ −σ ₁ ) Is designed to be within a certain range, so that when used in an ink jet recording method, it is possible to obtain a high-quality recorded image with excellent ejection stability and suppressed bleeding on a recording material. And a suitable ink composition can be obtained.
[0018]
The present invention also provides a dynamic surface tension (σ) when the bubble frequency is 10 Hz. ₁₀ ) And the dynamic surface tension (σ) when the bubble frequency is 1 Hz. ₁ ) Is 20 to 70 mN / m.
[0019]
According to the present invention, when the bubble frequency is 10 Hz, the dynamic surface tension (σ ₁₀ ) And the dynamic surface tension (σ) when the bubble frequency is 1 Hz. ₁ ) Is 20 mN / m or more and 70 mN / m or less. σ ₁₀ And σ ₁ Is less than 20 mN / m, the permeability to the absorptive recording material becomes too high, so that when the ink composition adheres to the absorptive recording material, the ink composition spreads from the impact point to the periphery and is formed. The outline of the recorded image becomes unclear. Also, σ ₁₀ And σ ₁ Exceeds 70 mN / m, the permeability to the absorbent recording material is too low, and the drying property on the absorbent recording material is reduced. Further, the wettability between the ink composition and the inner wall of the ink chamber is deteriorated, the supply of the ink composition to the ink chamber is delayed, and it becomes difficult to fill the ink chamber with the ink composition. Drops cannot be ejected. In addition, it is difficult to form a new surface of the ink composition in a desired shape at the discharge port provided at the tip of the ink chamber, that is, it is difficult to control the meniscus, so that the ink composition droplets are continuously formed at high speed. Cannot be discharged. Therefore, as described above, when the bubble frequency is 10 Hz, the dynamic surface tension (σ ₁₀ ) And the dynamic surface tension (σ) when the bubble frequency is 1 Hz. ₁ ) Is set to 20 mN / m or more and 70 mN / m or less, ₁₀ And σ ₁ And the difference d (= σ ₁₀ −σ ₁ ) Is designed to be within a certain range, so that when used in an ink jet recording method, it is possible to obtain a high quality recorded image while suppressing the bleeding on the recording material while having excellent ejection stability. And a suitable ink composition can be obtained.
[0020]
The present invention is further characterized in that it further contains a surfactant.
According to the present invention, since the ink composition further contains a surfactant, the aforementioned dynamic surface tension (σ) at a bubble frequency of 10 Hz is used. ₁₀ ) And the dynamic surface tension at a bubble frequency of 1 Hz (σ ₁ ) Can be easily controlled.
[0021]
Further, the invention is characterized in that the medium contains water.
According to the present invention, since the medium contains water, bleeding on the absorptive recording material can be suppressed, and the drying property can be improved.
[0022]
Further, the present invention is characterized in that the medium contains at least one of glycol ethers and polyhydric alcohols.
[0023]
According to the present invention, the medium contains at least one of glycol ethers and polyhydric alcohols having a low vapor pressure, so that a wetting effect can be obtained and the ejection stability can be improved.
[0024]
Further, the invention is characterized in that the coloring material contains a dye.
According to the present invention, since the coloring material contains a dye, clogging can be suppressed and ejection stability can be improved.
[0025]
Further, the invention is characterized in that the coloring material contains a pigment.
According to the present invention, since the coloring material contains a pigment, a recorded image having excellent light fastness and water fastness can be obtained.
[0026]
Further, the invention is characterized in that the coloring material contains a pigment having a hydrophilic group.
According to the invention, the coloring material includes a pigment having a hydrophilic group. As a result, a recorded image having excellent light fastness and water fastness can be obtained. Further, since the pigment has a hydrophilic group, it can be stably dispersed in the water-containing ink composition. Therefore, since the occurrence of clogging can be suppressed, it is possible to obtain an ink composition capable of obtaining a recorded image having excellent light fastness and water fastness without impairing the ejection stability.
[0027]
Further, the present invention is characterized in that the surfactant includes a nonionic surfactant.
[0028]
According to the present invention, since the surfactant contains a nonionic surfactant that is hardly affected by the coexisting electrolyte, regardless of whether the electrolyte is added to the ink composition, Dynamic surface tension at a frequency of 10 Hz (σ ₁₀ ) And the dynamic surface tension at the bubble frequency of 1 Hz (σ ₁ D) (= σ) ₁₀ −σ ₁ ) Can be within a certain range.
[0029]
Further, the present invention is characterized in that the surfactant is contained at a critical micelle concentration or more.
[0030]
According to the present invention, the surfactant is contained at or above the critical micelle concentration. Although the surface tension of a solution containing a surfactant decreases with increasing surfactant up to the critical micelle concentration, it is almost constant above the critical micelle concentration. Therefore, as described above, by containing the surfactant at or above the critical micelle concentration, the effect of the surfactant is sufficiently exhibited, and the dynamic surface at the above-described bubble frequency of 10 Hz controlled by the surfactant is controlled. Tension (σ ₁₀ ) And the dynamic surface tension at a bubble frequency of 1 Hz (σ ₁ ) Can be made substantially constant values, so that an ink composition having uniform properties can be obtained.
[0031]
In the present invention, the pigment may be C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4.
[0032]
According to the present invention, the pigment is C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4, so that an ink composition capable of realizing a recorded image having excellent cyan coloring properties can be obtained.
[0033]
In the present invention, the pigment may be C.I. I. Pigment Red 122, C.I. I. Pigment Red 209 and C.I. I. And at least one pigment selected from the group consisting of CI Pigment Violet 19.
[0034]
According to the present invention, the pigment is C.I. I. Pigment Red 122, C.I. I. Pigment Red 209 and C.I. I. Since it contains at least one pigment selected from the group consisting of CI Pigment Violet 19, an ink composition capable of realizing a recorded image having excellent magenta coloring properties can be obtained.
[0035]
In the present invention, the pigment may be C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 138, C.I. I. Pigment Yellow 150 and C.I. I. And at least one pigment selected from the group consisting of CI Pigment Yellow 180.
[0036]
According to the present invention, the pigment is C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 138, C.I. I. Pigment Yellow 150 and C.I. I. Since it contains at least one pigment selected from the group consisting of CI Pigment Yellow 180, it is possible to obtain an ink composition capable of realizing a recorded image having excellent yellow color developability.
[0037]
Further, the invention is characterized in that the pigment contains carbon black.
According to the present invention, since the pigment contains carbon black, it is possible to obtain an ink composition capable of realizing a recorded image having excellent black coloring properties.
[0038]
Further, the present invention is a recording method for recording an image by adhering an ink composition on a recording material,
The recording method is characterized in that any one of the ink compositions of the present invention is used for the ink composition.
[0039]
According to the present invention, since any one of the ink compositions of the present invention is used in a recording method of recording an image by depositing the ink composition on a recording material, a high-quality recorded image can be stably obtained. Can be provided.
[0040]
Further, the present invention is a recording method for recording an image by ejecting droplets of the ink composition by applying pressure to the ink composition, and adhering the droplets on a recording material,
The recording method is characterized in that any one of the ink compositions of the present invention is used for the ink composition.
[0041]
According to the present invention, a recording method for recording an image by applying pressure to an ink composition to eject droplets of the ink composition and attaching the droplets to a recording material, that is, an ink jet recording method Since any one of the ink compositions of the present invention is used, stable ejection is possible and a high-quality recorded image can be stably provided.
[0042]
Further, the present invention provides the ink composition, wherein at least the pigment is C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4, and an ink composition containing at least one pigment selected from the group consisting of C.I. I. Pigment Red 122, C.I. I. Pigment Red 209 and C.I. I. Pigment Violet 19, and an ink composition containing at least one pigment selected from the group consisting of C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 138, C.I. I. Pigment Yellow 150 and C.I. I. And an ink composition containing at least one pigment selected from the group consisting of CI Pigment Yellow 180.
[0043]
According to the present invention, the ink composition includes at least an ink composition capable of realizing a recorded image having excellent cyan coloring property, an ink composition capable of realizing a recorded image having excellent magenta coloring property, and yellow. And an ink composition capable of realizing a recorded image having excellent color developability. By superimposing these three types of ink compositions, a black recorded image with a high density can be obtained. Therefore, by using the above three types of ink compositions, various colors can be expressed, so that a full-color recorded image having excellent coloring properties can be provided.
[0044]
Further, the present invention provides the ink composition, wherein at least the pigment is C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4, and an ink composition containing at least one pigment selected from the group consisting of C.I. I. Pigment Red 122, C.I. I. Pigment Red 209 and C.I. I. Pigment Violet 19, and an ink composition containing at least one pigment selected from the group consisting of C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 138, C.I. I. Pigment Yellow 150 and C.I. I. Pigment Yellow 180, and an ink composition containing at least one pigment selected from the group consisting of Pigment Yellow 180 and an ink composition containing the pigment containing carbon black.
[0045]
According to the present invention, the ink composition includes at least an ink composition capable of realizing a recorded image having excellent cyan coloring property, an ink composition capable of realizing a recorded image having excellent magenta coloring property, and yellow. And an ink composition capable of realizing a recorded image having excellent black color developing properties. An ink composition capable of realizing a recorded image having excellent cyan color development, an ink composition capable of realizing a recorded image having excellent magenta color development, and an ink composition capable of realizing a recorded image having excellent yellow color development. By superimposing the three types of ink compositions with the object, a black recorded image having a high density can be obtained. Therefore, various colors can be expressed by using the four types of ink compositions obtained by adding the above-described three types of ink compositions to the above-described three types of ink compositions and the above-described ink composition capable of realizing a recorded image having excellent black coloring properties. Therefore, it is possible to provide a full-color recorded image having excellent coloring properties.
[0046]
According to the present invention, there is provided a recorded image recorded by the recording method.
[0047]
According to the present invention, a recorded image is recorded by the recording method, so that a high-quality recorded image can be obtained.
[0048]
In the present invention, the pigment may be C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4, an ink composition comprising at least one pigment,
The pigment is C.I. I. Pigment Red 122, C.I. I. Pigment Red 209 and C.I. I. An ink composition containing at least one pigment selected from the group consisting of CI Pigment Violet 19;
The pigment is C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 138, C.I. I. Pigment Yellow 150 and C.I. I. Pigment yellow 180, and an ink composition containing at least one pigment selected from the group consisting of CI Pigment Yellow 180.
[0049]
According to the present invention, the ink set has an ink composition capable of realizing a recorded image having excellent cyan coloring properties, an ink composition capable of realizing a recorded image having excellent magenta coloring properties, and has excellent yellow coloring properties. An ink composition capable of realizing a recorded image. By superimposing these three types of ink compositions, a black recorded image with a high density can be realized. That is, the ink set containing the above-described three types of ink compositions is excellent in color balance. Therefore, various colors can be expressed by using the ink set containing the above-described three types of ink compositions, so that a full-color recorded image having excellent color developability can be realized.
[0050]
In the present invention, the pigment may be C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4, an ink composition comprising at least one pigment,
The pigment is C.I. I. Pigment Red 122, C.I. I. Pigment Red 209 and C.I. I. An ink composition containing at least one pigment selected from the group consisting of CI Pigment Violet 19;
The pigment is C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 138, C.I. I. Pigment Yellow 150 and C.I. I. Pigment Yellow 180, an ink composition containing at least one pigment selected from the group consisting of
An ink set, wherein the pigment includes an ink composition containing carbon black.
[0051]
According to the present invention, the ink set has an ink composition capable of realizing a recorded image having excellent cyan coloring properties, an ink composition capable of realizing a recorded image having excellent magenta coloring properties, and has excellent yellow coloring properties. Includes an ink composition capable of realizing a recorded image and an ink composition capable of realizing a recorded image having excellent black color developing properties. An ink composition capable of realizing a recorded image having excellent cyan color development, an ink composition capable of realizing a recorded image having excellent magenta color development, and an ink composition capable of realizing a recorded image having excellent yellow color development. By superimposing the three types of ink compositions on the object, a black recorded image with a high density can be realized. That is, the ink set containing the above-described three types of ink compositions is excellent in color balance. Therefore, by using an ink set including four kinds of ink compositions obtained by adding the above-mentioned three kinds of ink compositions to the above-mentioned ink compositions capable of realizing a recorded image having excellent black color developing properties, various colors can be obtained. Can be realized, so that a full-color recorded image having excellent color developability can be realized.
[0052]
The present invention also provides an ink tank for storing any of the ink compositions of the present invention,
An ink chamber having an ejection port for ejecting droplets of the ink composition, wherein the ink composition is supplied from the ink tank,
A piezoelectric element that generates a strain in response to an applied voltage, and applies a pressure to the ink composition provided in at least a part of the ink chamber and housed in the ink chamber,
An electrode provided for applying a voltage to the piezoelectric element.
[0053]
According to the present invention, the ink head stores any one of the ink compositions of the present invention by an ink tank, and is separated from the ink tank by an ink chamber having a discharge port for discharging droplets of the ink composition. A piezoelectric element that stores the supplied ink composition and generates distortion in response to an applied voltage, wherein the ink is stored in the ink chamber by a piezoelectric element provided in at least a part of the ink chamber. Pressure is applied to the composition, and a voltage is applied to the piezoelectric element by an electrode. Accordingly, it is possible to obtain a piezo-type ink head that can discharge droplets of the ink composition from the discharge ports in accordance with the voltage applied to the piezoelectric element. Further, since the ink tank stores any one of the ink compositions of the present invention, it is possible to stably eject droplets of the ink composition from the ejection openings. The use of such an ink head makes it possible to realize a highly reliable piezo-type inkjet recording apparatus.
[0054]
The present invention also provides an ink tank for storing any of the ink compositions of the present invention,
An ink chamber having an ejection port for ejecting droplets of the ink composition, wherein the ink composition is supplied from the ink tank,
A heating element provided in at least a part of the ink chamber, for applying pressure to the ink composition by heating the ink composition contained in the ink chamber to generate air bubbles;
An electrode provided for applying a voltage to the heating element.
[0055]
According to the present invention, the ink head stores any of the ink compositions of the present invention by an ink tank, and is separated from the ink tank by an ink chamber having a discharge port for discharging droplets of the ink composition. The ink composition to be supplied is housed, and the ink composition housed in the ink chamber is heated by a heating element provided in at least a part of the ink chamber to generate air bubbles. Pressure is applied to the heating element, and a voltage is applied to the heating element by an electrode. This makes it possible to obtain a thermal inkjet type ink head capable of discharging droplets of the ink composition from the discharge ports in accordance with the voltage applied to the heating element. Further, since the ink tank stores any one of the ink compositions of the present invention, it is possible to stably eject droplets of the ink composition from the ejection openings. By using such an ink head, a highly reliable thermal inkjet type inkjet recording apparatus can be realized.
[0056]
Further, the present invention is a recorded image characterized in that a recording is performed by attaching a droplet of the ink composition ejected by the piezo type ink head onto a recording material.
[0057]
According to the present invention, the recorded image is formed on the recording material by droplets of the ink composition ejected by the piezo-type ink head capable of stably ejecting the ink composition droplets as described above. The image is recorded by being attached to the recording medium, so that a high-quality recorded image can be stably obtained.
[0058]
Further, the present invention is a recorded image characterized in that a recording is performed by attaching a droplet of an ink composition ejected by the thermal ink jet type ink head onto a recording material.
[0059]
According to the present invention, the recorded image is formed by a droplet of the ink composition ejected by a thermal inkjet type ink head capable of stably ejecting the ink composition droplet as described above. Since the image is recorded by being attached to the upper side, a high-quality recorded image can be stably obtained.
[0060]
BEST MODE FOR CARRYING OUT THE INVENTION
The ink composition according to the first embodiment of the present invention contains at least a colorant and a medium, and includes a bubble frequency among dynamic surface tensions measured at a measurement temperature of 24 ° C. to 26 ° C. by a maximum bubble pressure method. Is 10 Hz, the dynamic surface tension (σ ₁₀ ) And the dynamic surface tension when the bubble frequency is 1 Hz (σ ₁ D) (= σ) ₁₀ −σ ₁ ) Satisfies the following expression (1).
0 mN / m ≦ d ≦ 7 mN / m (1)
[0061]
The maximum bubble pressure method, which is a method for measuring the dynamic surface tension, will be described.
The maximum bubble pressure method is to insert a thin tube into the liquid and form an interface between the liquid and gas in the liquid by generating bubbles from the tip of the thin tube, and when the pressure difference between the inside of the bubble and the outside of the bubble becomes maximum, That is, this method measures the pressure difference (ΔP) when the radius of the bubble becomes equal to the radius (r) of the thin tube, and obtains the surface tension (σ) from the measured value. The surface tension (σ) is obtained from the following equation (2).
σ = ΔP · r / 2 (2)
[0062]
By changing the bubble frequency, which is the number of bubbles generated per unit time, the dynamic surface tension from a slow motion state to a fast motion state can be obtained. By determining the dynamic surface tension from a slow motion state to a fast motion state, a change in the dynamic properties of the liquid can be evaluated.
[0063]
The ink composition of the present embodiment is used in a recording method for recording an image by attaching the ink composition onto a recording material, for example, an ink jet recording method or a recording method using a writing instrument such as a pen. By using the ink composition of the present embodiment, a high-quality recorded image can be stably provided.
[0064]
Among the recording methods described above, the ink composition of the present embodiment is suitably used for an ink jet recording method. In the ink jet recording method, an image is recorded by applying pressure to the ink composition to discharge droplets of the ink composition, and attaching the droplets to a recording material. By using the ink composition of the present embodiment in an ink jet recording method, stable ejection can be performed and a high-quality recorded image can be stably provided.
[0065]
In an ink jet recording apparatus that records an image using an ink jet recording method, when droplets of the ink composition are continuously ejected, the ejection port provided at the tip of the ink chamber in the ink head regenerates the ink composition. Since the surface is constantly generated, the movement of the ink composition is fast, and the influence of the dynamic surface tension at a high frequency of about 10 Hz, which corresponds to the dynamic surface tension in the fast-moving state, is large. On the other hand, in the ink chamber, after the ink composition is ejected, the reduced volume of the ink composition is ejected and supplied from the ink tank by capillary action, so that the movement of the ink composition is slow and the ink composition is slow. The effect of the dynamic surface tension at a low frequency of about 1 Hz corresponding to the dynamic surface tension in the above is large. That is, during ejection, both the dynamic surface tension at a high frequency and the dynamic surface tension at a low frequency are affected. It is necessary to balance the dynamic surface tension at low frequencies with the dynamic surface tension at low frequencies. In addition, the movement of the ink composition when recording an image by attaching a droplet of the ink composition onto a recording material is fast at the moment when the droplet lands on the recording material, but gradually slows down thereafter, In the case of an absorbent recording material, the ink composition slowly penetrates into the recording material. That is, the dynamic surface tension of the ink composition changes from a dynamic surface tension in a fast-moving state to a dynamic surface tension in a slow-moving state, so that the dynamic surface tension at a high frequency and the dynamic surface tension at a low frequency change. If the difference from the target surface tension is large, it takes time until the ink composition dries on the recording material, and bleeding occurs. In addition, it penetrates too much to cause strikethrough.
[0066]
As described above, among the dynamic surface tensions measured at a measurement temperature of 24 ° C. or more and 26 ° C. or less by the maximum bubble pressure method, the ink composition of the present embodiment has a dynamic surface tension when the bubble frequency is 10 Hz. (Σ ₁₀ ) And the dynamic surface tension when the bubble frequency is 1 Hz (σ ₁ D) (= σ) ₁₀ −σ ₁ ) Satisfies the above equation (1), that is, the difference between the dynamic surface tension at a high frequency of 10 Hz and the dynamic surface tension at a low frequency of 1 Hz is within a certain range. Therefore, when used in the inkjet recording method, it is possible to obtain an ink composition that is excellent in ejection stability and that can suppress bleeding on a recording material and obtain a high-quality recorded image.
[0067]
Hereinafter, the reason for limiting the range of design in the ink composition of the present embodiment will be described.
[0068]
σ ₁₀ And σ ₁ And the difference d (= σ ₁₀ −σ ₁ ) Exceeds 7 mN / m, the balance between the dynamic surface tension at a high frequency and the dynamic surface tension at a low frequency deteriorates, and it is impossible to discharge droplets stably. In addition, drying takes a long time on the recording material to cause bleeding, thereby deteriorating the image quality. Therefore, it was set to 7 mN / m or less.
[0069]
σ ₁₀ And σ ₁ And the difference d (= σ ₁₀ −σ ₁ ) Is less than 0 mN / m, the dynamic surface tension at a low frequency increases, the wettability of the ink composition with respect to the members constituting the ink head decreases, and the ink chamber may be filled with the ink composition. It becomes difficult. Therefore, it was set to 0 mN / m or more.
[0070]
The dynamic surface tension (σ ₁₀ ) And the dynamic surface tension at a bubble frequency of 1 Hz (σ ₁ ) Is preferably from 20 mN / m to 70 mN / m, and more preferably from 20 mN / m to 50 mN / m.
[0071]
σ ₁₀ And σ ₁ Is less than 20 mN / m, the permeability to the absorptive recording material becomes too high, so that when the ink composition adheres to the absorptive recording material, the ink composition spreads from the impact point to the periphery and is formed. The outline of the recorded image becomes unclear. Also, σ ₁₀ And σ ₁ Exceeds 70 mN / m, the permeability to the absorbent recording material is too low, and the drying property on the absorbent recording material is reduced. Further, the wettability between the ink composition and the inner wall of the ink chamber is deteriorated, the supply of the ink composition to the ink chamber is delayed, and it becomes difficult to fill the ink chamber with the ink composition. Drops cannot be ejected. In addition, it is difficult to form a new surface of the ink composition in a desired shape at the discharge port provided at the tip of the ink chamber, that is, it is difficult to control the meniscus, so that the ink composition droplets are continuously formed at high speed. Cannot be discharged. Therefore, it was set to 20 mN / m or more and 70 mN / m or less.
[0072]
The viscosity of the ink composition of the present embodiment at 25 ° C. is preferably 20 mPa · s or less, more preferably 15 mPa · s or less. If the viscosity at 25 ° C. of the ink composition exceeds 20 mPa · s, it is not possible to stably eject droplets of the ink composition when used in an inkjet recording method. Therefore, it was set to 20 mPa · s or less.
[0073]
As the medium, water or an organic solvent is used.
The medium preferably contains water. Thereby, bleeding on the absorptive recording material can be suppressed, and the drying property can be improved.
[0074]
The content of water in the ink composition is preferably from 30% by weight to 95% by weight, and more preferably from 30% by weight to 85% by weight. When the content of water is less than 30% by weight, the content of the organic solvent in the ink composition becomes too large, so that an additive that can be dissolved or dispersed in water is stably present in the ink composition. Becomes difficult. In addition, the viscosity is significantly increased, and may deviate from the appropriate viscosity as the ink composition. When the content of water exceeds 95% by weight, the content of the organic solvent becomes too small, so that the wettability of the ink composition cannot be maintained. Therefore, the content is 30% by weight or more and 95% by weight or less.
[0075]
Specific examples of the organic solvent include amides such as dimethylformamide and dimethylacetamide, polyethylene glycol, polypropylene glycol, ethylene glycol, diethylene glycol, thiodiglycol, propylene glycol, triethylene glycol, 1,5-pentanediol, Polyhydric alcohols such as 1,4-butanediol, 1,2-hexanediol, 1,3-propanediol, glycerin and 1,2,6-hexanetriol, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether , Diethylene glycol monoethyl ether, triethylene glycol monobutyl ether, propylene glycol monoethyl ether, Ethers of polyhydric alcohols such as glycol ethers such as ethylene glycol monomethyl ether and ethylene glycol monophenyl ether; sulfur-containing compounds such as sulfolane and dimethyl sulfoxide; nitrogen such as 2-pyrrolidone, N-methylpyrrolidone and ε-caprolactam Examples of the organic solvent include, but are not limited to, compounds containing, oxygen-containing compounds such as γ-butyrolactone, and polyfunctional compounds such as dimethylaminoethanol, diethylaminoethanol, triethanolamine, and morpholine. One of these organic solvents may be used alone, or two or more thereof may be used as a mixture.
[0076]
Among the above-mentioned organic solvents, glycol ethers and polyhydric alcohols have a low vapor pressure, and by containing them in the ink composition, a wetting effect can be obtained and ejection stability can be improved. Preferably contains at least one of glycol ethers and polyhydric alcohols. Among the glycol ethers and polyhydric alcohols, glycol ethers such as diethylene glycol monobutyl ether, propylene glycol monobutyl ether, triethylene glycol monobutyl ether or tetraethylene glycol monobutyl ether, or glycerin, which is a polyhydric alcohol, 1,2- Hexanediol or 1,5-pentanediol has a vapor pressure at 25 ° C. of 0.05 mmHg or less and has an excellent wetting effect. Therefore, it is more preferable to use these as a medium.
[0077]
The content of the organic solvent in the ink composition is preferably from 3% by weight to 70% by weight, more preferably from 3% by weight to 50% by weight. When the content of the organic solvent is less than 3% by weight, drying of the ink composition is fast and it is difficult to maintain wettability. If the content of the organic solvent exceeds 70% by weight, there may be cases where a water-soluble or water-dispersible additive cannot be stably present in the ink composition. Further, depending on the type of the organic solvent used, the viscosity increases significantly, and may exceed the appropriate viscosity as the ink composition. Therefore, the content is set to 3% by weight or more and 70% by weight or less. However, the content of the organic solvent in the ink composition is preferably 3% by weight or more and 40% by weight or less, more preferably 3% by weight or more and 30% by weight or less when the ink composition contains water as a main component. % By weight or less. When the ink composition contains water as a main component and the content of the organic solvent exceeds 40% by weight, the quality of the obtained recorded image deteriorates and the drying of the ink composition depends on the type of coloring material used. A time delay occurs. Therefore, the content is set to 3% by weight or more and 40% by weight or less.
[0078]
A dye, a pigment, or a mixture thereof is used as the coloring material. Dyes and pigments may contain these or may be attached thereto.
[0079]
By using a dye as the coloring material, the occurrence of clogging can be suppressed, and the ejection stability can be improved. By using a pigment as a coloring material, a recorded image having excellent light fastness and water fastness can be obtained.
[0080]
To reproduce each color in the full-color ink jet recording method, three color ink compositions of cyan (Cyan; abbreviation: M), magenta (Magenta; abbreviation: M), and yellow (Yellow; abbreviation: Y) are used. Each color is represented by mixing the ink compositions of the above. However, since it is difficult to reproduce black when the three colors are mixed, a black (Black; abbreviation: B) ink composition is generally used for expressing black. By changing the color of the coloring material to be contained, a cyan, magenta, yellow or black ink composition can be obtained.
[0081]
Although the dye is not particularly limited, when the ink composition contains water, a water-soluble dye such as an acid dye, a direct dye, a reactive dye, and a food dye is preferably used. Among these, it is preferable to use one having excellent water resistance, light resistance or safety.
[0082]
Specific examples of the dye include the following dyes, but the dye is not limited thereto. In the following, the dyes are indicated by color index (abbreviation: CI) numbers.
[0083]
Examples of the dye used in the cyan ink composition include C.I. I. Acid Blue 7, 9, 29, 45, 92 and 249, C.I. I. Direct Blue 1,2,6,15,22,25,71,76,79,86,90,98,163,165,199 and 202, and C.I. I. Reactive blues 1, 2, 7, 14, 15, 23, 32, 38, 41, 63, 80 and 95. Among these, C.I. I. Acid Blue 7 and 9, and C.I. I. It is preferable to use at least one dye selected from the group consisting of Direct Blue 199.
[0084]
Examples of the dye used in the magenta ink composition include C.I. I. Acid Red 1, 8, 13, 14, 18, 26, 27, 35, 37, 42, 52, 82, 87, 89, 92, 97, 106, 111, 114, 115, 134, 186, 249, 254 and 289, C.I. I. Direct Red 1, 4, 9, 13, 17, 20, 28, 31, 39, 80, 81, 83, 89, 225 and 227, C.I. I. Direct Orange 26, 29, 62 and 102, and C.I. I. Reactive Red 1, 14, 17, 25, 26, 32, 37, 44, 46, 55, 58, 60, 66, 74, 79, 96, 97, 141, 147, 180 and 181. Among these, C.I. I. Acid Red 52 and 289, and C.I. I. It is preferable to use at least one dye selected from the group consisting of Reactive Reds 58, 141 and 180.
[0085]
Examples of the dye used in the yellow ink composition include C.I. I. Acid Yellow 1, 7, 17, 23, 42, 44, 79 and 142, C.I. I. Direct Yellow 1, 12, 24, 26, 33, 44, 50, 86, 120, 132, 142 and 144, and C.I. I. And reactive yellows 1, 5, 11, 13, 14, 20, 21, 22, 25, 40, 47, 51, 55, 65, and 67. Among these, C.I. I. Acid Yellow 17 and 23, and C.I. I. It is preferable to use at least one dye selected from the group consisting of Direct Yellow 86.
[0086]
Examples of the dye used in the black ink composition include C.I. I. Food black 2, C.I. I. Direct Black 19, 22, 32, 38, 51, 56, 71, 74, 75, 77, 154, 168 and 171 and C.I. I. And reactive blacks 3, 4, 7, 11, 12 and 17. Among these, C.I. I. Food black 2 and C.I. I. It is preferable to use at least one dye of the direct black 154.
[0087]
These dyes are used within a range where they are stably dissolved at room temperature. Since this range is different for each dye, the content of the dye in the ink composition is not particularly limited, but is preferably 0.1% by weight to 10% by weight.
[0088]
As the pigment, any pigment may be used as long as it can be dispersed in a solution, but a pigment excellent in light resistance or safety is preferably used.
[0089]
Specific examples of the pigment include the following pigments, but the pigment is not limited thereto. In the following, pigments are indicated by color index (CI) numbers.
[0090]
Examples of the pigment used in the cyan ink composition include C.I. I. Pigment Blue 1, 2, 15, 16, 17, 21, 22, 60 and 64.
[0091]
Examples of the pigment used in the magenta ink composition include C.I. I. Pigment Red 2, 3, 5, 16, 23, 31, 49, 57, 63, 122 and 209, and C.I. I. Pigment Violet 19 and the like.
[0092]
Examples of the pigment used in the yellow ink composition include C.I. I. Pigment Yellow 1, 2, 3, 5, 12, 74, 138, 150 and 180.
[0093]
Examples of the pigment used in the black ink composition include carbon black such as channel black, furnace black, thermal black, and lamp black.
[0094]
Among these pigments, cyan ink compositions include C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4. The magenta ink composition includes C.I. I. Pigment Red 122, C.I. I. Pigment Red 209 and C.I. I. It is preferable to use at least one pigment selected from the group consisting of CI Pigment Violet 19. The yellow ink composition also includes C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 138, C.I. I. Pigment Yellow 150 and C.I. I. It is preferable to use at least one pigment selected from the group consisting of CI Pigment Yellow 180. Further, it is preferable to use at least one pigment selected from the above-described carbon blacks in the black ink composition. By using these pigments, it is possible to obtain an ink composition capable of realizing a recorded image having excellent coloring properties of cyan, magenta, yellow and black.
[0095]
Further, ink compositions of three colors of cyan, magenta and yellow using these preferred pigments, namely, C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4, a cyan ink composition using at least one pigment, and C.I. I. Pigment Red 122, C.I. I. Pigment Red 209 and C.I. I. Pigment Violet 19, a magenta ink composition using at least one pigment selected from the group consisting of C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 138, C.I. I. Pigment Yellow 150 and C.I. I. Pigment Yellow 180 and a yellow ink composition using at least one pigment selected from the group consisting of Pigment Yellow 180, by superimposing the three types of ink compositions, the result is close to a recorded image formed using the black ink composition. A black recorded image with a high density can be obtained. That is, an ink set containing these three types of ink compositions is excellent in color balance. Therefore, an ink set containing these three types of ink compositions, or an ink set containing four types of ink compositions obtained by adding a black ink composition using carbon black to these three types of ink compositions is used. By using this, various colors can be expressed, so that a full-color recorded image with excellent color developability can be realized.
[0096]
When the ink composition contains water, the pigment preferably has one or more hydrophilic groups selected from the group consisting of, for example, a carboxyl group, a hydroxyl group, an amino group, and a sulfonic acid group. These hydrophilic groups may be directly introduced by chemically modifying the pigment surface, or may be introduced by coating the pigment surface with a polymer having these hydrophilic groups. These hydrophilic groups may be in the form of a salt.
[0097]
The pigment having a hydrophilic group can be stably dispersed in the water-containing ink composition. Therefore, clogging can be suppressed by using a pigment having a hydrophilic group as a coloring material, so that a recorded image having excellent light resistance and water resistance can be obtained without impairing ejection stability.
[0098]
These pigments are used within a range where they are stably dispersed at room temperature. Since this range is different for each pigment, the content of the pigment in the ink composition is not particularly limited, but is preferably 0.1% by weight to 10% by weight.
[0099]
It is preferable that the ink composition of the present embodiment further contains a surfactant. Thereby, the dynamic surface tension (σ at the bubble frequency of 10 Hz described above) ₁₀ ) And the dynamic surface tension at a bubble frequency of 1 Hz (σ ₁ ) Can be easily controlled.
[0100]
As the surfactant, any of a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant may be used. The type of nonionic, anionic or cationic surfactant is selected according to the type of electrolyte contained in the ink composition. For example, when the ink composition contains an anionic substance, a nonionic or anionic surfactant is used. These surfactants may be used in combination. At this time, the types of surfactants such as nonionic, anionic and cationic surfactants may be the same or different.
[0101]
Among the above-mentioned surfactants, the nonionic surfactants are hardly affected by the coexisting electrolyte, and regardless of whether or not the electrolyte is added to the ink composition, the above-mentioned dynamic at the bubble frequency of 10 Hz. Surface tension (σ ₁₀ ) And the dynamic surface tension at the bubble frequency of 1 Hz (σ ₁ D) (= σ) ₁₀ −σ ₁ ) Can be within a certain range, so that this is preferably used as a surfactant.
[0102]
Specific examples of the nonionic surfactant include surfactants represented by the following general formulas (I), (II), (III), (IV), (V), and (VI). The nonionic surfactant is not limited to this.
[0103]
Embedded image

[0104]
Embedded image

[0105]
Embedded image

[0106]
Embedded image

[0107]
Embedded image

[0108]
Embedded image

[0109]
In the general formula (I), m represents an integer or decimal number of 0 to 30, and n represents an integer or decimal number of 0 to 30. However, the sum (m + n) of m and n is an integer of 0 to 30 or a decimal number.
[0110]
In the general formula (II), k represents an integer or a decimal number of 11 to 13, and 1 represents an integer or a decimal number of 3 to 30.
[0111]
In the general formula (III), h represents an integer or decimal number of 0 to 11, i represents an integer or decimal number of 0 to 11, and j represents an integer or decimal number of 3 to 50. Here, the sum (h + i) of h and i is an integer or a decimal number of 9 to 11.
[0112]
In the general formula (IV), w represents an integer or a decimal number from 0 to 11, x represents an integer or a decimal number from 5 to 9, y represents an integer or a decimal number from 2.5 to 5, and z represents a number from 0 to 5. Indicates an integer or decimal number of 9. Here, the sum (w + z) of w and z is an integer or a decimal number of 9 to 11.
[0113]
In the general formula (V), p represents an integer or decimal number of 0 to 78, q represents an integer or decimal number of 2 to 15, and r represents an integer or decimal number of 0 to 18.
[0114]
In the general formula (VI), s represents an integer or decimal number of 0 to 30, and t represents an integer or decimal number of 0 to 30. However, the sum of s and t (s + t) is an integer of 0 to 30 or a decimal number. U represents an integer or decimal number of 0 to 10, and v represents an integer or decimal number of 0 to 10. However, the sum (u + v) of u and v is an integer of 0 to 10 or a decimal number.
[0115]
The surfactant is preferably contained in the ink composition at or above the critical micelle concentration. Although the surface tension of a solution containing a surfactant decreases with increasing surfactant up to the critical micelle concentration, it is almost constant above the critical micelle concentration. Therefore, as described above, by incorporating a surfactant at or above the critical micelle concentration, the effect of the surfactant is sufficiently exerted, and the dynamic surface tension (σ) at the above-mentioned bubble frequency of 10 Hz controlled by the surfactant is controlled. ₁₀ ) And the dynamic surface tension at a bubble frequency of 1 Hz (σ ₁ ) Can be made substantially constant values, so that an ink composition having uniform properties can be obtained.
[0116]
Although the critical micelle concentration is different for each surfactant, in each case of nonionic surfactant, anionic surfactant, cationic surfactant and amphoteric surfactant, the critical micelle concentration is 0.001 at 25 ° C. % By weight to about 3% by weight.
[0117]
When a pigment is used as a coloring material, the ink composition of the present embodiment preferably contains a binder resin. By including the binder resin, the peeling of the pigment from the recording material can be prevented.
[0118]
As the binder resin, for example, one or more selected from the group consisting of a polyester resin, an acrylic resin, a styrene-acrylic copolymer resin, a polyester-acrylic copolymer resin, and the like are used.
[0119]
In addition, the ink composition of the present embodiment includes, in addition to a coloring material, a medium, a surfactant, and a binder resin, various additives such as a fungicide, a pH adjuster, a chelating agent, a rust inhibitor, an ultraviolet absorber, and the like. May be included.
[0120]
As a fungicide, sodium dehydroacetate, sodium benzoate, sodium sorbitanate and the like are suitably used.
[0121]
As the pH adjuster, triethanolamine, sodium hydroxide, sodium carbonate, sodium nitrate, potassium nitrate and the like are suitably used.
[0122]
Among the dynamic surface tensions that contain at least a coloring material and a medium and are measured at a measurement temperature of 24 ° C. or more and 26 ° C. or less by the maximum bubble pressure method, the dynamic surface tension (σ) when the bubble frequency is 10 Hz ₁₀ ) And the dynamic surface tension when the bubble frequency is 1 Hz (σ ₁ D) (= σ) ₁₀ −σ ₁ ), The ink composition satisfying the above formula (1) is, for example, 0.5% to 15% by weight of a coloring material, 3% to 70% by weight of an organic solvent, and 29% to 95% by weight. % Of water and 0.001% to 5% by weight of a surfactant.
[0123]
FIG. 1 is an exploded perspective view showing a simplified configuration of an ink head 1 according to a second embodiment of the present invention, and FIG. 2 is a configuration of a head plate 10 that constitutes the ink head 1 shown in FIG. It is a perspective view which expands and shows a part. In FIG. 1, the description of the drive electrode 13 shown in FIG. 2 is omitted because the figure is complicated and the understanding is difficult.
[0124]
The ink head 1 includes a head plate 10 having a bottom wall portion 11 made of a piezoelectric material and a plurality of partition portions 12, a top plate 20 provided on an upper surface of the partition portion 12, and a plurality of ejection ports 31. A nozzle plate 30 provided at one end of the section 12, a back plate (not shown) provided at the other end of the partition section 12, and an ink tank 50 provided at the top of the top plate 20 and having an opening 51. It is comprised including. The plurality of partition walls 12 are arranged in parallel on the bottom wall 11 at predetermined intervals, and are formed by the plurality of partition walls 12, the bottom wall 11, the top plate 20, the nozzle plate 30, and the back plate (not shown). Are formed. A common ink supply path 21 communicating with each ink chamber 40 and an ink supply pipe 22 connecting the common ink supply path 21 and the opening 51 of the ink tank 50 are formed in the top plate 20. The ink composition 60 of the first embodiment is stored in the ink tank 50, and the ink composition 60 is supplied to each ink chamber 40 via the common ink supply path 21.
[0125]
As shown in FIG. 2, a drive electrode 13 for applying a voltage to the plurality of partition walls 12 is formed on the bottom wall 11 of the head plate 10 and the surface of the plurality of partition walls 12 facing the ink chamber 40. Further, the piezoelectric material forming the plurality of partition portions 12 is polarized in the direction of arrow 70, and the plurality of partition portions 12 function as piezoelectric elements.
[0126]
The ink head 1 configured in this manner is a piezo-type ink that can discharge droplets of the ink composition 60 from the discharge ports 31 according to the voltage applied to the plurality of partition walls 12 that are piezoelectric elements. Head.
[0127]
An operation principle when the ink composition 60 is ejected from the ink chamber 40 in the ink head 1 will be described. FIG. 3 is a cross-sectional view of the ink head 1 shown in FIG. Here, the operation when the ink composition 60 is ejected from the ink chamber 40b will be described.
[0128]
When no voltage is applied to the partition portions 12a and 12b constituting the ink chamber 40b, that is, between the drive electrode 13b of the ink chamber 40b and the drive electrode 13a of the ink chamber 40a adjacent to the ink chamber 40b, and between the drive chamber 13b and the ink chamber 40b When there is no potential difference between the drive electrode 13b of the ink chamber 40b and the drive electrode 13c of the ink chamber 40c adjacent to the ink chamber 40b, the ink chamber 40b is filled with the ink composition 60 supplied from the ink tank 50 by capillary action. It is in the state that was done. Similarly, the ink chambers 40a and 40c are also filled with the ink composition 60.
[0129]
When a voltage is applied to the drive electrode 13a and the drive electrode 13c, a potential difference is generated between the drive electrode 13b and the drive electrode 13a, and between the drive electrode 13b and the drive electrode 13c. A voltage is applied to 12a and 12b. This voltage generates electric fields in the directions of arrows 71 and 72 in the partition portions 12a and 12b, respectively. The action of the electric field causes distortion in the partition portions 12a and 12b constituting the ink chamber 40b, and the ink chamber 40b side Deform to be convex. As a result, a pressure wave is generated, a large pressure is applied to the ink composition 60 filled in the ink chamber 40b, and the droplet of the ink composition 60 is ejected from the ejection port 31 shown in FIG.
[0130]
When the application of the voltage to the drive electrode 13a and the drive electrode 13c is stopped, the shape of the partition walls 12a and 12b returns to the original shape, and the volume of the ink chamber 40b returns to the original volume. 1 is supplied from the ink tank 50 via the common ink supply path 21 shown in FIG. 1, and the ink chamber 40b returns to the initial state filled with the ink composition 60.
[0131]
In the ink head 1 according to the present embodiment, as described above, the ink tank 50 stores the ink composition 60 according to the first embodiment, and the ink composition 60 is supplied to the ink chamber 40 and is discharged from the ejection port 31. Since the droplets are ejected as droplets, droplets of the ink composition 60 can be ejected from the ejection openings 31 stably. By using such an ink head, a highly reliable piezo-type inkjet recording apparatus can be realized, and a high-quality recorded image can be stably obtained.
[0132]
As described above, in the present embodiment, the partition 12 forming the ink chamber 40 is formed of a piezoelectric material and functions as a piezoelectric element. However, the present invention is not limited thereto. May be formed of a material other than a piezoelectric material, and a piezoelectric element may be provided inside or outside the partition.
[0133]
FIG. 4 is an exploded perspective view showing a simplified configuration of an ink head 2 according to a third embodiment of the present invention, and FIG. 5 is a plan view showing a part of the configuration of the ink head 2 shown in FIG. It is. In FIG. 5, the top plate 20 and the ink tank 50 shown in FIG. The ink head 2 according to the present embodiment is similar to the ink head 1 according to the second embodiment, and the corresponding parts are denoted by the same reference numerals and description thereof will be omitted.
[0134]
It should be noted that the head plate 100 is a substrate 101, a plurality of partitions 102 arranged in parallel on the substrate 101 at predetermined intervals, and a heating element provided on the surface of the substrate 101 facing the ink chamber 40. The configuration includes a heater 103 and drive electrodes 104 and 105 for applying a voltage to the heater 103.
[0135]
The ink head 2 configured as described above is a thermal inkjet type ink head that can discharge droplets of the ink composition 60 from the discharge port 31 in accordance with a voltage applied to the heater 103 that is a heating element. is there.
[0136]
The principle of operation when the ink composition 60 is ejected from the ink chamber 40 in the ink head 2 will be described. FIG. 6 is a cross-sectional view schematically showing a state in which droplets 61 of the ink composition 60 are ejected from the ink chamber 40. FIG. 6 shows a cross-sectional configuration taken along the line II of the ink head 2 shown in FIG.
[0137]
When no voltage is applied to the heater 103, the ink chamber 40 is filled with the ink composition 60 in the same manner as when no voltage is applied to the partition 12 in the ink head 1 of the second embodiment. Has become.
[0138]
When a voltage is applied to the heater 103 by the drive electrodes 104 and 105, the heater 103 generates heat, and the ink composition 60 filled in the ink chamber 40 is heated to generate bubbles 62. As a result, a pressure wave is generated, a large pressure is applied to the ink composition 60 filled in the ink chamber 40, and the droplet 61 of the ink composition 60 is discharged from the discharge port 31.
[0139]
When the application of the voltage to the heater 103 is stopped, the ink composition 60 in the ink chamber 40 is cooled, the bubbles 62 disappear, and the restored volume of the ink composition 60 is supplied to the common ink supply shown in FIG. The ink is supplied from the ink tank 50 via the passage 21, and the ink chamber 40 returns to the initial state where the ink composition 60 is filled.
[0140]
In the ink head 2 according to the present embodiment, similarly to the ink head 1 according to the above-described second embodiment, the ink tank 50 stores the ink composition 60 according to the first embodiment. Since the ink composition 60 is supplied to the chamber 40 and ejected from the ejection port 31 as the droplet 61, the droplet 61 of the ink composition 60 can be ejected from the ejection port 31 stably. By using such an ink head, a highly reliable thermal inkjet type ink jet recording apparatus can be realized, and a high quality recorded image can be stably obtained.
[0141]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In the present embodiment, recording an image may be referred to as printing or printing.
[0142]
<Ink composition>
In the preparation of the ink composition, by changing the types and contents of the coloring material, the organic solvent and the surfactant, and the contents of the binder resin and water as shown in Table 1, the dynamics at the above-described bubble frequency of 10 Hz were changed. Surface tension (σ ₁₀ ) And the dynamic surface tension at the bubble frequency of 1 Hz (σ ₁ D) (= σ) ₁₀ −σ ₁ ) Satisfies the above formula (1), and ink compositions of Comparative Examples 1 to 4 where d does not satisfy the above formula (1). In Table 1, the unit of the value in each column is parts by weight, and the total amount of each ink composition of Examples 1 to 7 and Comparative Examples 1 to 4 is 100 parts by weight, respectively. In Table 1, TEGBE represents triethylene glycol monobutyl ether, PEG 400 represents polyethylene glycol having a molecular weight of 400, and general formula (I) represents the general formula (I). ) Represents a surfactant represented by the general formula (II), and the general formula (III) represents a surfactant represented by the general formula (III). Wherein the general formula (IV) represents the surfactant represented by the general formula (IV), the general formula (V) represents the surfactant represented by the general formula (V), Surfactant 1 represents a surfactant represented by the following structural formula (VII), and fluorinated surfactant 2 represents Represents a surfactant represented by the structural formula (VIII). The concentration of the surfactant in the ink composition is higher than the critical micelle concentration in Examples 1 to 7 and Comparative Examples 1 to 3, and lower than the critical micelle concentration in Comparative Example 4.
[0143]
Embedded image

[0144]
Embedded image

[0145]
The dynamic surface tension of each of the ink compositions of Examples 1 to 7 and Comparative Examples 1 to 4 was measured using a surface tensiometer (BP-4 manufactured by Kyowa Interface Science Co., Ltd.) with a bubble frequency of 0.5 Hz to Performed at 35 Hz.
[0146]
Table 2 shows the dynamic surface tension (σ) of each of the ink compositions of Examples 1 to 7 and Comparative Examples 1 to 4 at a bubble frequency of 10 Hz. ₁₀ ) And the dynamic surface tension at a bubble frequency of 1 Hz (σ ₁ ) Measured value (mN / m), σ ₁₀ And σ ₁ And the difference d (= σ ₁₀ −σ ₁ ) And the measurement temperature (° C.) at that time.
[0147]
[Table 1]

[0148]
[Table 2]

[0149]
With respect to each of the obtained ink compositions of Examples 1 to 7 and Comparative Examples 1 to 4, the ejection stability and the image quality of the obtained recorded image when used in the ink jet recording method were evaluated as follows.
[0150]
(Discharge stability)
The ink tanks of the ink jet recording apparatus obtained by modifying a commercially available ink jet recording apparatus (AJ2000 manufactured by Sharp Corporation) so that the ink head 1 shown in FIG. Each of the ink compositions of Comparative Examples 1 to 4 was filled, and the printing density was 5%. Printing was performed continuously. In the test, when the ink tank is empty, the ink composition is refilled, printing is performed until ink droplets are not ejected from the nozzle and printing can no longer be performed, and by that point printing can be completed completely The obtained number was determined as a printable number and used as an evaluation index of ejection stability. The case where the number of printable sheets exceeded 200 sheets was evaluated as good (○), the case of 150 to 200 sheets was evaluated as acceptable (△), and the case of less than 150 sheets was evaluated as poor (×).
[0151]
(image quality)
The ink jet recording apparatus (AJ2000 manufactured by Sharp Corp .: AJ2000) was remodeled so that the ink head 1 shown in FIG. Each of the ink compositions of Comparative Examples 1 to 4 was filled, and a specific pattern was printed on plain paper for a copying machine (product number: SF4AM3) manufactured by Sharp Corporation to form an image for evaluation. After the evaluation image was allowed to stand for one day, the line width of the set pattern was set to 100, and the relative value of the line width of the pattern of each evaluation image to this was determined as an evaluation index of image quality. The case where the relative value of the line width is less than 150 and there is almost no bleeding is regarded as good (○), the case where it is 150 or more and 250 or less and there is some bleeding is possible (△), and the case where it exceeds 250 and there is much bleeding is bad. (X).
Table 3 shows the above evaluation results.
[0152]
[Table 3]

[0153]
Dynamic surface tension at a bubble frequency of 10 Hz (σ ₁₀ ) And the dynamic surface tension at the bubble frequency of 1 Hz (σ ₁ D) (= σ) ₁₀ −σ ₁ The ink compositions of Examples 1 to 7 satisfying the above-mentioned formula (1) exhibited good ejection stability and image quality. On the other hand, in the ink compositions of Comparative Examples 1 to 4 in which d was larger than 7 and deviated from the above formula (1) to a larger extent, both the ejection stability and the image quality were poor or acceptable.
[0154]
As described above, the dynamic surface tension at the bubble frequency of 10 Hz (σ ₁₀ ) And the dynamic surface tension at the bubble frequency of 1 Hz (σ ₁ D) (= σ) ₁₀ −σ ₁ ) Satisfies the above formula (1), when used in an ink jet recording method, it is possible to obtain a high quality recorded image which is excellent in ejection stability and suppresses bleeding on a recording material. A good ink composition was obtained.
[0155]
<Ink set>
By combining the ink compositions of Examples 2 to 6 and Comparative Examples 1 to 3 as cyan, magenta and yellow ink compositions as shown in Table 4, C.I. I. A cyan ink composition containing at least one pigment selected from the group consisting of C.I. Pigment Blue 15: 3 and 15: 4; I. Pigment Red 122, 209 and C.I. I. Pigment Violet 19, a magenta ink composition containing at least one pigment selected from the group consisting of C.I. I. Pigment Yellow 74, 138, 150, and 180. An ink set 1 including at least one pigment selected from the group consisting of a yellow ink composition and a cyan, magenta, and yellow ink composition. Comparative Ink Sets 1 to 3 each containing a pigment different from the aforementioned pigment, and Comparative Ink Set 4 in which all of the cyan, magenta and yellow ink compositions contained a pigment different from the above pigment were obtained. .
[0156]
[Table 4]

[0157]
Using each of the obtained Example Ink Set 1 and Comparative Example Ink Sets 1 to 4, a commercially available ink jet recording apparatus (AJ2000 manufactured by Sharp Corporation) was used, and an ink jet recording apparatus obtained by remodeling was used. A black image was formed on a glossy paper (product number: AJ-K4AG) manufactured by printing with a printing ratio of each of the cyan, magenta and yellow ink compositions of 1: 1: 1. The same image was formed using the ink composition of Example 7 which was a black ink composition.
[0158]
For each of the obtained black images, a spectrophotometer (manufactured by X-Rite: X-Rite938) was used to obtain L ^* a ^* b ^* Lightness index L in color system (CIE: 1976) ^* And chromaticity index a ^* , B ^* Was measured.
[0159]
Evaluation of the test results was performed as follows. Chromaticity index a of a black image formed using the ink composition of Example 7 ^* To A1, b ^* Is B2, and a chromaticity index a of a black image formed using each of the ink set 1 of the example and the ink sets 1 to 4 of the comparative examples is shown. ^* To A2, b ^* As B2, Δa represented by the following equation (3) ^* b ^* Was determined and used as an evaluation index for black reproducibility.
Δa ^* b ^* = ｛(A1-A2) ² + (B1-B2) ² ｝ ^1/2 … (3)
Δa ^* b ^* Is 20 or less (Δa ^* b ^* ≦ 20) is regarded as good (○), and exceeds 20 (Δa ^* b ^* > 20) The case was evaluated as defective (x). Table 5 shows the evaluation results.
[0160]
[Table 5]

[0161]
From Table 5, the black image obtained by superimposing the three types of ink compositions included in the example ink set 1 was obtained by superposing the three types of ink compositions included in the comparative example ink sets 1 to 4, respectively. As compared with the black image obtained, it was found that the black image was a dark image having a dark density close to the black image formed using the ink composition of Example 7. That is, it was found that Example Ink Set 1 had better black reproducibility and better color balance than Comparative Example Ink Sets 1 to 4.
[0162]
As described above, C.I. I. A cyan ink composition containing at least one pigment selected from the group consisting of C.I. Pigment Blue 15: 3 and 15: 4; I. Pigment Red 122, 209 and C.I. I. Pigment Violet 19, a magenta ink composition containing at least one pigment selected from the group consisting of C.I. I. Pigment Yellow 74, 138, 150 and 180, an ink set having an excellent color balance could be obtained by combining with a yellow ink composition containing at least one pigment selected from the group consisting of Pigment Yellow 74, 138, 150 and 180.
[0163]
【The invention's effect】
As described above, according to the present invention, the difference between the dynamic surface tension at the bubble frequency of 10 Hz and the dynamic surface tension at the bubble frequency of 1 Hz measured at the measurement temperature of 24 to 26 ° C. by the maximum bubble pressure method is constant. Since the ink composition is designed so as to fall within the range, when used in an ink jet recording method, the ink is excellent in ejection stability and can suppress bleeding on a recording material to obtain a high-quality recorded image. A composition can be obtained.
[0164]
Further, according to the present invention, the dynamic surface tension at the bubble frequency of 10 Hz and the dynamic surface tension at the bubble frequency of 1 Hz are selected in suitable ranges. Accordingly, it is possible to obtain an ink composition that can suppress bleeding on a recording material and obtain a high-quality recorded image.
[0165]
Further, according to the present invention, since a surfactant is further contained, the dynamic surface tension of the ink composition including the dynamic surface tension at the bubble frequency of 10 Hz and the dynamic surface tension at the bubble frequency of 1 Hz can be easily controlled. be able to.
[0166]
Further, according to the present invention, since the medium contains water, bleeding on the absorptive recording material can be suppressed, and the drying property can be improved.
[0167]
Further, according to the present invention, since the medium contains at least one of glycol ethers and polyhydric alcohols having a low vapor pressure, a wetting effect can be obtained and the ejection stability can be improved.
[0168]
Further, according to the present invention, since the coloring material contains a dye, it is possible to suppress the occurrence of clogging and improve the ejection stability.
[0169]
Further, according to the present invention, since the coloring material contains a pigment, a recorded image having excellent light fastness and water fastness can be obtained.
[0170]
Further, according to the present invention, since the coloring material contains a pigment having a hydrophilic group, clogging can be suppressed, and a recorded image having excellent light fastness and water fastness can be obtained without impairing ejection stability. A possible ink composition can be obtained.
[0171]
Further, according to the present invention, the surfactant contains a nonionic surfactant which is hardly affected by the coexisting electrolyte. Therefore, regardless of whether or not the electrolyte is added to the ink composition, the surfactant has a bubble frequency of 10 Hz. The difference between the dynamic surface tension and the dynamic surface tension at a bubble frequency of 1 Hz can be within a certain range.
[0172]
Further, according to the present invention, since the surfactant is contained at or above the critical micelle concentration, the effect of the surfactant is sufficiently exerted, and the dynamic surface tension at the bubble frequency of 10 Hz controlled by the surfactant and the bubble frequency of 1 Hz are controlled. Can be made almost constant values, and an ink composition having uniform properties can be obtained.
[0173]
Further, according to the present invention, it is possible to obtain an ink composition capable of realizing a recorded image having excellent cyan coloring properties.
[0174]
Further, according to the present invention, an ink composition capable of realizing a recorded image having excellent magenta coloring property can be obtained.
[0175]
Further, according to the present invention, it is possible to obtain an ink composition capable of realizing a recorded image having excellent yellow color developability.
[0176]
Further, according to the present invention, it is possible to obtain an ink composition capable of realizing a recorded image having excellent black coloring properties.
[0177]
Further, according to the present invention, a high-quality recorded image can be stably provided.
Further, according to the present invention, stable ejection is possible, and a high-quality recorded image can be stably provided.
[0178]
Further, according to the present invention, since various colors can be expressed, it is possible to provide a full-color recorded image having excellent color developability.
[0179]
Further, according to the present invention, a high quality recorded image can be obtained.
Further, according to the present invention, since an ink set having an excellent color balance can be obtained, various colors can be expressed, and a full-color recorded image having an excellent coloring property can be realized.
[0180]
Further, according to the present invention, in a piezo type ink head capable of discharging droplets of the ink composition from the discharge port in accordance with the voltage applied to the piezoelectric element, the ink composition can be stably discharged from the discharge port. Droplets can be ejected.
[0181]
Further, according to the present invention, in a thermal inkjet type ink head capable of discharging droplets of the ink composition from the discharge port in accordance with the voltage applied to the heating element, the ink composition can be stably discharged from the discharge port. Droplets can be ejected.
[0182]
Further, according to the present invention, the recording image is formed such that ink composition droplets ejected by a piezo-type ink head capable of stably ejecting ink composition droplets are adhered onto a recording material. Therefore, a high-quality recorded image can be stably obtained.
[0183]
Further, according to the present invention, the recording image is formed such that the droplets of the ink composition ejected by the thermal inkjet type ink head capable of stably ejecting the ink composition droplets adhere to the recording material. Therefore, a high quality recorded image can be stably obtained.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a simplified configuration of an ink head 1 according to a second embodiment of the present invention.
FIG. 2 is an enlarged perspective view showing a part of a configuration of a head plate 10 constituting the ink head 1 shown in FIG.
FIG. 3 is a cross-sectional view of the ink head 1 shown in FIG.
FIG. 4 is an exploded perspective view showing a simplified configuration of an ink head 2 according to a third embodiment of the present invention.
FIG. 5 is a plan view showing a part of the configuration of the ink head 2 shown in FIG.
FIG. 6 is a cross-sectional view schematically showing a state in which a droplet 61 of an ink composition 60 is ejected from an ink chamber 40.
[Explanation of symbols]
1, 2 ink head
10 Head plate
11 Bottom wall
12, 12a, 12b Partition wall
13, 13a, 13b, 13c Drive electrode
20 Top plate
21 Common ink supply path
22 Ink supply pipe
30 Nozzle plate
31 Discharge port
40, 40a, 40b, 40c Ink chamber
50 ink tank
51 Opening
60 Ink composition
61 droplet
62 bubbles
100 head plate
101 substrate
102 partition wall
103 heater
104,105 drive electrode

Claims (25)

In an ink composition containing at least a coloring material and a medium,
Among the dynamic surface tensions measured at the measurement temperature of 24 to 26 ° C. by the maximum bubble pressure method, the dynamic surface tension when the bubble frequency is 10 Hz (σ ₁₀ ) and the dynamic surface tension when the bubble frequency is 1 Hz An ink composition characterized in that a difference d (= σ ₁₀ −σ ₁ ) from the tension (σ ₁ ) satisfies the following formula (1).
0 mN / m ≦ d ≦ 7 mN / m (1) The dynamic surface tension (σ ₁₀ ) when the bubble frequency is 10 Hz and the dynamic surface tension (σ ₁ ) when the bubble frequency is 1 Hz are 20 to 70 mN / m. Item 7. The ink composition according to Item 1, The ink composition according to claim 1, further comprising a surfactant. The ink composition according to any one of claims 1 to 3, wherein the medium includes water. The ink composition according to any one of claims 1 to 4, wherein the medium includes at least one of glycol ethers and polyhydric alcohols. The ink composition according to claim 1, wherein the coloring material includes a dye. The ink composition according to claim 1, wherein the coloring material includes a pigment. The ink composition according to any one of claims 4 to 6, wherein the coloring material includes a pigment having a hydrophilic group. The ink composition according to any one of claims 3 to 8, wherein the surfactant includes a nonionic surfactant. The ink composition according to any one of claims 3 to 9, wherein the surfactant is contained at a concentration equal to or higher than the critical micelle concentration. The pigment is C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4. The ink composition according to claim 7, further comprising at least one pigment. The pigment is C.I. I. Pigment Red 122, C.I. I. Pigment Red 209 and C.I. I. The ink composition according to any one of claims 7 to 10, further comprising at least one pigment selected from the group consisting of CI Pigment Violet 19. The pigment is C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 138, C.I. I. Pigment Yellow 150 and C.I. I. The ink composition according to any one of claims 7 to 10, further comprising at least one pigment selected from the group consisting of CI Pigment Yellow 180. The ink composition according to any one of claims 7 to 10, wherein the pigment includes carbon black. A recording method for recording an image by adhering an ink composition on a recording material,
15. A recording method, wherein the ink composition according to claim 1 is used as the ink composition. A recording method for recording an image by ejecting droplets of the ink composition by applying pressure to the ink composition, and attaching the droplets to a recording material,
15. A recording method, wherein the ink composition according to claim 1 is used as the ink composition. 15. The ink composition according to claim 15, wherein at least the ink composition according to claim 11, the ink composition according to claim 12, and the ink composition according to claim 13 are used. 16. The recording method according to item 16. As the ink composition, at least the ink composition according to claim 11, the ink composition according to claim 12, the ink composition according to claim 13, and the ink composition according to claim 14 are used. 17. The recording method according to claim 15, wherein the recording method is performed. A recorded image recorded by the recording method according to claim 15. An ink composition according to claim 11,
An ink composition according to claim 12,
An ink set comprising the ink composition according to claim 13. An ink composition according to claim 11,
An ink composition according to claim 12,
An ink composition according to claim 13,
An ink set comprising the ink composition according to claim 14. An ink tank for storing the ink composition according to any one of claims 1 to 14,
An ink chamber having an ejection port for ejecting droplets of the ink composition, wherein the ink composition is supplied from the ink tank,
A piezoelectric element that generates a strain in response to an applied voltage, and applies a pressure to the ink composition provided in at least a part of the ink chamber and housed in the ink chamber,
An electrode provided for applying a voltage to the piezoelectric element. An ink tank for storing the ink composition according to any one of claims 1 to 14,
An ink chamber having an ejection port for ejecting droplets of the ink composition, wherein the ink composition is supplied from the ink tank,
A heating element provided in at least a part of the ink chamber, for applying pressure to the ink composition by heating the ink composition contained in the ink chamber to generate air bubbles;
An electrode provided for applying a voltage to the heating element. A recorded image formed by attaching droplets of an ink composition ejected by the ink head according to claim 22 onto a recording material. A recorded image, wherein a droplet of the ink composition ejected by the ink head according to claim 23 is recorded by being attached to a recording material.

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