JP2004181803A - Inkjet image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet image forming method, by which the high maximum density is obtained, in which pure black tinged with neither red nor blue can be reproduced, which is excellent in resistance to fingerprint adhesion, lustrous properties, gloss difference, resistance to bronzing and scratch resistance and during the high speed printing of which the deterioration of image quality is small. <P>SOLUTION: In this inkjet image forming method, the image is formed through a process for printing the image with a pigment ink on an inkjet recording medium and a process for processing the formed image under heat and pressure so as to give liquid including resin and substantially not including coloring agent to at least some part of an image region having a density of at least 1.0. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０１４５】
（下層用塗布液１の調製）
上記シリカ分散液６００ｍｌを４０℃で攪拌しながら、以下の各添加剤を順次混合して下層用塗布液１を調製した。
【０１４６】
ポリビニルアルコール（クラレ工業株式会社製：ＰＶＡ２０３）の
１０％水溶液 ６ｍｌ
ポリビニルアルコール（クラレ工業株式会社製：ＰＶＡ２３５）の
７％水溶液 １８５ｍｌ
サポニン（５０％水溶液） 適量
純水 全量を１０００ｍｌに仕上げた
（表層用塗布液１の調製）
適量の水を４０℃で攪拌しながら、以下の各添加剤を順次混合して表層用塗布液１を調製した。
【０１４７】
熱可塑性樹脂（スチレン−アクリル系ラテックス Ｔｇ７３℃、平均粒径
０．９μｍ、固形分４０％） １６６ｇ
ポリビニルアルコール（クラレ工業株式会社製：ＰＶＡ２３５）の
７％水溶液 １８ｍｌ
消泡剤ＳＮ３８１（サンノプコ株式会社製） ６．２ｍｇ
サポニン（５０％水溶液） 適量
純水 全量を１０００ｍｌに仕上げた
上記各添加剤を混合した後、４０℃で粘度が４５ｍＰａ・ｓとなるように適宜純水を加えて、表層用塗布液１を調製した。
【０１４８】
（記録媒体１の作製）
両面をポリエチレンで被覆した紙支持体（厚みが２２０μｍでインク吸収層面のポリエチレン中にはポリエチレンに対して１３質量％のアナターゼ型酸化チタン含有）に、支持体側から第１層とし上記下層用塗布液１をスライドホッパーで塗布した後、その上に第２層目として上記表層用塗布液１をスライドホッパーにて塗布、乾燥して記録媒体１を作製した。なお、塗布液は４０℃に加温して塗布し、塗布直後に０℃に保たれた冷却ゾーンで２０秒冷却した後、２５℃の風（相対湿度１５％）で６０秒間、４５℃の風（相対湿度が２５％）で６０秒間、５０℃の風（相対湿度が２５％）で６０秒間順次乾燥し、２０〜２５℃、相対湿度が４０〜６０℃の雰囲気下で２分間調湿して試料を巻き取った。なお、下層の乾燥膜厚は３０μｍ、表層の乾燥膜厚は１０μｍとなるように塗布量を制御した。この記録媒体１をロール幅１２７ｍｍ、長さ１００ｍのロール状に加工した。
【０１４９】
〔記録媒体２の作製〕
上記記録媒体１の作製において、表層用塗布液１に代えて下記表層用塗布液２を用い、表層の乾燥膜厚７μｍとなるように、下層用塗布液１及び表層用塗布液２を同時重層塗布を行った以外は同様にして、記録媒体２を作製した。
【０１５０】
（表層用塗布液２の調製）
記録媒体１の作製で用いた下層用塗布液１を４０℃で撹拌し、そこへ熱可塑性樹脂（スチレン−アクリル系ラテックス Ｔｇ７３℃、平均粒径０．２μｍ、固形分４０％）を熱可塑性微粒子／フィラー（シリカ）の固形分比が５０／５０になるように加えて、さらに４０℃、粘度が４５ｍＰａ・ｓとなるように適宜純水を加えて、表層用塗布液２を調製した。
【０１５１】
〔記録媒体３〜５の作製〕
上記記録媒体２の作製において、熱可塑性微粒子／フィラー（シリカ）の固形分比を、それぞれ４０／６０、６０／４０、７０／３０に変更した以外は同様にして、記録媒体３〜５を作製した。
【０１５２】

上記各添加剤を混合し、０．３ｍｍのジルコニアビーズを体積率で６０％充填した横型ビーズミル（アシザワ社製 システムゼータミニ）を用いて分散し、イエロー顔料分散体１を得た。得られたイエロー顔料の平均粒径は１１２ｎｍであった。
【０１５３】

上記各添加剤を混合し、０．３ｍｍのジルコニアビーズを体積率で６０％充填した横型ビーズミル（アシザワ社製 システムゼータミニ）を用いて分散し、マゼンタ顔料分散体１を得た。得られたマゼンタ顔料の平均粒径は１０５ｎｍであった。
【０１５４】

上記各添加剤を混合し、０．３ｍｍのジルコニアビーズを体積率で６０％充填した横型ビーズミル（アシザワ社製 システムゼータミニ）を用いて分散し、シアン顔料分散体１を得た。得られたシアン顔料の平均粒径は８７ｎｍであった。
【０１５５】

上記各添加剤を混合し、０．３ｍｍのジルコニアビーズを体積率で６０％充填した横型ビーズミル（アシザワ社製 システムゼータミニ）を用いて分散し、ブラック顔料分散体１を得た。得られたブラック顔料の平均粒径は７５ｎｍであった。
【０１５６】
（顔料インクセット１の調製）
〈イエロー濃インク１の調製〉
イエロー顔料分散体１ １５質量％
エチレングリコール ２０質量％
ジエチレングリコール １０質量％
界面活性剤（サーフィノール４６５ 日信化学工業社製） ０．１質量％
イオン交換水 ５４．９質量％
以上の各組成物を混合、攪拌し、１μｍフィルターでろ過し、本発明の水性顔料インクであるイエロー濃インク１を調製した。該インク中の顔料の平均粒径は１２０ｎｍであり、表面張力γは３６ｍＮ／ｍであった。
【０１５７】
〈イエロー淡インク１の調製〉
イエロー顔料分散体１ ３質量％
エチレングリコール ２５質量％
ジエチレングリコール １０質量％
界面活性剤（サーフィノール４６５ 日信化学工業社製） ０．１質量％
イオン交換水 ６１．９質量％
以上の各組成物を混合、攪拌し、１μｍフィルターでろ過し、本発明の水性顔料インクであるイエロー淡インク１を調製した。該インク中の顔料の平均粒径は１１８ｎｍであり、表面張力γは３７ｍＮ／ｍであった。
【０１５８】
〈マゼンタ濃インク１の調製〉
マゼンタ顔料分散体１ １５質量％
エチレングリコール ２０質量％
ジエチレングリコール １０質量％
界面活性剤（サーフィノール４６５ 日信化学工業社製） ０．１質量％
イオン交換水 ５４．９質量％
以上の各組成物を混合、攪拌し、１μｍフィルターでろ過し、本発明の水性顔料インクであるマゼンタ濃インク１を調製した。該インク中の顔料の平均粒径は１１３ｎｍであり、表面張力γは３５ｍＮ／ｍであった。
【０１５９】
〈マゼンタ淡インク１の調製〉
マゼンタ顔料分散体１ ３質量％
エチレングリコール ２５質量％
ジエチレングリコール １０質量％
界面活性剤（サーフィノール４６５ 日信化学工業社製） ０．１質量％
イオン交換水 ６１．９質量％
以上の各組成物を混合、攪拌し、１μｍフィルターでろ過し、本発明の水性顔料インクであるマゼンタ淡インク１を調製した。該インク中の顔料の平均粒径は１１０ｎｍであり、表面張力γは３７ｍＮ／ｍであった。
【０１６０】
〈シアン濃インク１の調製〉
シアン顔料分散体１ １０質量％
エチレングリコール ２０質量％
ジエチレングリコール １０質量％
界面活性剤（サーフィノール４６５ 日信化学工業社製） ０．１質量％
イオン交換水 ５９．９質量％
以上の各組成物を混合、攪拌し、１μｍフィルターでろ過し、本発明の水性顔料インクであるシアン濃インク１を調製した。該インク中の顔料の平均粒径は９５ｎｍであり、表面張力γは３６ｍＮ／ｍであった。
【０１６１】
〈シアン淡インク１の調製〉
シアン顔料分散体１ ２質量％
エチレングリコール ２５質量％
ジエチレングリコール １０質量％
界面活性剤（サーフィノール４６５ 日信化学工業社製） ０．２質量％
イオン交換水 ６２．８質量％
以上の各組成物を混合、攪拌し、１μｍフィルターでろ過し、本発明の水性顔料インクであるシアン淡インク１を調製した。該インク中の顔料の平均粒径は９２ｎｍであり、表面張力γは３３ｍＮ／ｍであった。
【０１６２】
〈ブラック濃インク１の調製〉
ブラック顔料分散体１ １０質量％
エチレングリコール ２０質量％
ジエチレングリコール １０質量％
界面活性剤（サーフィノール４６５ 日信化学工業社製） ０．１質量％
イオン交換水 ５９．９質量％
以上の各組成物を混合、攪拌し、１μｍフィルターでろ過し、本発明の水性顔料インクであるブラック濃インク１を調製した。該インク中の顔料の平均粒径は８５ｎｍであり、表面張力γは３５ｍＮ／ｍであった。
【０１６３】
〈ブラック淡インク１の調製〉
ブラック顔料分散体１ ２質量％
エチレングリコール ２５質量％
ジエチレングリコール １０質量％
界面活性剤（サーフィノール４６５ 日信化学工業社製） ０．１質量％
イオン交換水 ６２．９質量％
以上の各組成物を混合、攪拌し、１μｍフィルターでろ過し、本発明の水性顔料インクであるブラック淡インク１を調製した。該インク中の顔料の平均粒径は８９ｎｍであり、表面張力γは３６ｍＮ／ｍであった。
【０１６４】
〔顔料インクセット２の調製〕
上記顔料インクセット１で調製した８色の各インクに、それぞれアクリルエマルジョン（ヨドゾールＧＤ８６Ｂ Ｔｇ６０℃、平均粒径９０ｎｍ、日本ＮＣＳ社製）を８質量％相当添加した以外は同様にして、インク８色からなる顔料インクセット２を調製した。
【０１６５】
〔着色剤未含有液体（ＣＩインク）の調製〕
（ＣＩインク１の調製）
ポリビニルアルコールＰＶＡ１１７（クラレ製） 固形分１．０質量％
エチレングリコール ２２．０質量％
グリセリン ８．０質量％
トリエチレングリコールモノブチルエーテル ５．０質量％
２−ピロリドン ２．０質量％
サーフィノール４６５（日信化学工業社製） ０．５質量％
純水を加えて、１００質量％に仕上げた
（ＣＩインク２の調製）

（ＣＩインク３の調製）
上記ＣＩインク２の調製において、樹脂１を樹脂２（アクリル酸エステル共重合体：Ｔｇ ７５℃、平均粒径０．５μｍ）に変更した以外は同様にして、ＣＩインク３を調製した。
【０１６６】
（ＣＩインク４の調製）
上記ＣＩインク２の調製において、樹脂１を樹脂３（アクリル酸エステル共重合体：Ｔｇ ７５℃、平均粒径１．２μｍ）に変更した以外は同様にして、ＣＩインク４を調製した。
【０１６７】
（ＣＩインク５の調製）
上記ＣＩインク２の調製において、樹脂１を樹脂４（アクリル酸エステル共重合体：Ｔｇ ５６℃、平均粒径０．３μｍ）に変更した以外は同様にして、ＣＩインク５を調製した。
【０１６８】
《インクジェット画像形成》
図１に記載の加圧処理と加熱処理とを同時に行う加熱加圧ローラ対を有し、９個の記録ヘッドを装備したインクジェットプリンターに、上記調製した顔料インクセット（濃淡８色）とＣＩインクとをセットし、前記作製した記録媒体１〜５、コニカ（株）製フォトジェットペーパーＱＰ（表中ではＱＰと略す）、セイコーエプソン（株）製ＰＭ写真用紙（表中では、ＰＭと略す）とを、表１に記載の組み合わせで、出力条件１．５ｍ^２／時間で出射し、イエロー、マゼンタ、シアン、ブラックのベタ画像、縦及び横に１ｃｍ幅でＹ、Ｍ、Ｃ、Ｂ、Ｇ、Ｒ、Ｂｋの帯を各々描いた格子状テストチャートを出力した。
【０１６９】
なお、画像形成時のＣＩインクの出射領域は、下記の方法に従って決定した。
あらかじめ、８色の顔料インクのみを上記条件でプリントして作成したＹ、Ｍ、Ｃ、Ｂ、Ｇ、Ｒ、Ｂｋのウエッジ画像の反射濃度をＸ−ｒｉｔｅ９３８（Ｘ−ｒｉｔｅ社製）にて測定し、Ｙ、Ｍ、Ｃ濃度のいずれかが濃度１．０を超える領域のインク出射量を予め計測、設定しておき、上記の印字の際、前記設定インク出射量を超える画像領域にのみ、ＣＩインクを所定量出射するようにプログラムした。ただし、画像７の形成時には、ＣＩインクは用いなかった。
【０１７０】
その後、画像１は装置内の加熱加圧定着器を使用せず、１００℃のオーブンに５分間いれて処理を行い、画像２〜１５は、装置内の加熱加圧定着器にて、定着器の表面温度を１００℃、圧力５ＭＰａで加熱加圧処理を行った。
【０１７１】
《形成画像の特性評価》
上記方法により作成した形成画像について、下記の方法に従って各特性評価を行った。
【０１７２】
（画像濃度の測定）
上記作成した黒ベタ画像部について、反射濃度計（Ｘ−ｒｉｔｅ ９３８）にてＶｉｓｕａｌ濃度１を測定した。
【０１７３】
（指紋付着耐性）
上記作成した黒ベタ画像部に、１０人の被験者により指紋をつけた後、ティッシュペーパーにて指紋を軽く拭き取り、指紋のついた部分のｖｉｓｕａｌ濃度２を測定し、下式に従って濃度変化率を測定し、１０人の被験者による平均値を求めた。
【０１７４】
ΔＤ＝指紋処理後濃度（ｖｉｓｕａｌ濃度２）−未処理濃度（Ｖｉｓｕａｌ濃度１）
ΔＤが小さいほど、指紋付着後の濃度変動が少なく好ましいことを表す。
【０１７５】
（光沢感の評価）
上記作成した各色ベタ画像の光沢感について、２０人の観察者により以下に示す基準に則り分類評価してもらい、最も多かった分類のものを採用した。
【０１７６】
５：全ての色で良好な光沢感がある
４：グリーンとレッドの高画像濃度部分でやや光沢感に欠ける。
【０１７７】
３：イエロー、ブラック、グリーン、レッドの高画像濃度部分で光沢感に欠ける
２：イエロー、マゼンタ、シアン、ブラックの高画像濃度部分で光沢感に欠ける
１：全色全濃度で光沢感が低い
（Ｃ値の測定）
上記作成した黒ベタ画像部について、スガ試験機社製の写像性測定機（ＩＣＭ−１ＤＰ）を用いて、反射角６０°でＣ値の測定を行った。
【０１７８】
（光沢差の評価）
上記作成した黒ベタ画像部と未印字部（白地）とを目視にて比較し、光沢差の有無について判定した。
【０１７９】
（ブロンジング耐性の評価）
出力した各画像について、顔料特有の現象であり、画質低下の要因となるブロンジングについて、以下の方法で評価を行った。ブロンジングの評価は、画像を蛍光灯下で種々の角度（真上を９０°とし、真横を０°とした時、８０°、６０°、４５°、３０°）から観察し、下記の基準に則り評価を行った。
【０１８０】
３：いずれかの角度でもブロンジング（金属光沢）が認められない
２：一部の角度からの観察で、一部のインク画像で弱いブロンジングが認められる
１：ほぼ全ての角度でブロンジングが認められる
（耐傷性の評価）
上記形成した各画像のうち黒ベタ画像部を、２５℃、５０％ＲＨの雰囲気下で、スクラッチ強度試験機 ＨＥＩＤＯＮ−１８（ＨＥＩＤＯＮ社製）を用い、測定針は０．１ｍｍＲのサファイヤ針を用いて、スクラッチ強度の測定を行った。測定は、０〜１０ｇの荷重を１０ｃｍの範囲で変化させた引掻き試験を３回行い、画像に傷が入る最小荷重をスクラッチ強度と定義し、その測定値を耐傷性の尺度とした。
【０１８１】
（膜剥がれ耐性の評価）
上記のインクジェット画像形成において、画像の出力条件を３．０ｍ^２／時間に変更した以外は同様にして画像作成を行い、これらの各画像について、ロール紙４０ｍ相当の面積を目視観察し、膜はがれの有無を評価し、下記の基準に則り膜剥がれ耐性の評価を行った。
【０１８２】
４：画像出力速度が３ｍ^２／時間の条件でも、膜剥がれ発生しない
３：画像出力速度が２ｍ^２／時間の条件では膜剥がれの発生はないが、３ｍ^２／時間の条件では、１ｃｍ^２未満の膜剥がれが１〜５箇散在する
２：画像出力速度が２ｍ^２／時間の条件で、１ｃｍ^２未満の膜剥がれが１〜３箇散在する。
【０１８３】
１：画像出力速度が２ｍ^２／時間の条件で、１ｃｍ^２未満の膜はがれが４〜１０箇所認められ、かつ１ｃｍ^２以上の膜はがれも散在する
以上により得られた結果を、表１に示す。
【０１８４】
【表１】

【０１８５】
表１より明らかなように、濃度１．０以上の画像領域に、樹脂を含有し、かつ実質的に着色剤を含まない液体を付与した後、加熱及び加圧処理を施して形成した本発明の画像は、比較例に対し、特に、黒インク画像において、画像濃度やＣ値が高く、指紋付着耐性、光沢感、光沢差、ブロンジング耐性及び耐傷性に優れ、かつ高速印字を行った際での膜剥がれ耐性が良好であることが分かる。
【０１８６】
更に、上記作成した画像の黒ベタ部を、Ｊａｐａｎ Ｃｏｌｏｒの黒と比較した結果、本発明の画像は、Ｊａｐａｎ Ｃｏｌｏｒの黒に近い色調を有し、赤味や青みのない黒が再現されていたが、比較例である画像１の黒はやや赤味がかっていた。
【０１８７】
また、ＣＩインクの吐出安定性について、上記画像形成方法で印字し、１０日間放置した後、再度印字を行った結果、ＣＩインク１では出射不良が見られたが、ＣＩインク２〜５に関しては、出射不良が全く見られなかった。
【０１８８】
また、上記作成した各画像について、上記で評価を行った項目に加えて、各色ベタ画像でのビーディング発生や格子状テストチャートの境界でのカラーブリードを観測した結果、画像出力速度が２ｍ^２／時間の条件では、本発明の全ての画像でビーディング、カラーブリードは見られず、高画質画像が得られた。また、画像出力速度が３ｍ^２／時間の条件では、記録媒体１を用いた画像で、ビーディング、カラーブリードが多く発生し、写真画質としての使用に耐えない物であった。さらに、記録媒体１では画像の一部に膜はがれ等の画像欠陥が発生し、加熱加圧装置のローラ表面にも汚れが確認できた。これに対し、表層にシリカを混合した、記録媒体２〜５を用いた画像は、ビーディング、カラーブリードが発生しないか、或いは発生してもわずかであり、非常に良好な結果を確認することができた。
【０１８９】
【発明の効果】
本発明により、高い最大濃度が得られ、赤味や青みのない純黒を再現でき、指紋付着耐性、光沢性、光沢差、ブロンジング耐性、耐傷性に優れ、かつを高速印字でも画質劣化の少ないインクジェット画像形成方法を提供することができた。
【図面の簡単な説明】
【図１】本発明で用いられるインクジェット記録装置の一例を示す概略構成図。
【図２】本発明で用いられるインクジェット記録装置の他の一例を示す概略構成図。
【符号の説明】
１、１ａ 記録媒体
２ 記録媒体の搬送手段
２１ 搬送ローラ対
３ 記録ヘッド
３４ 記録媒体保持部
４ 加熱加圧手段
４１ 加熱ローラー
４２ 圧着ローラー
４３ 発熱体
４４ 加熱ベルト
４５ 下部圧着ベルト
４６ 従動ローラー
５ 温度センサ
６ 記録媒体の切断手段
６１、６２ カッタ
７ たるみ形成手段
７１ 第１のローラー対
７２ 第２のローラー対[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a novel inkjet image forming method.
[0002]
[Prior art]
2. Description of the Related Art In recent years, the progress of inkjet technology has been remarkable, and it has come to be called photographic image quality in combination with improvements in printer technology, ink technology, and dedicated recording medium technology. With the improvement of image quality, the storability of ink-jet images has been compared with conventional silver halide photographs, and in many dye inks, the water resistance of ink-jet images and the movement of colorants such as poor bleeding resistance are accompanied. Deterioration and deterioration accompanied by a chemical reaction peculiar to the colorant, such as weakness to light resistance and resistance to oxidation gas, have been pointed out.
[0003]
On the other hand, in order to improve the storability of a dye ink image, use of a pigment ink has been often proposed. However, in the case of pigment ink, glossiness such as a silver salt photograph cannot be obtained, or metallic gloss called bronzing may be observed, which is not preferable. Further, at present, sufficient image storability is not obtained simply by using pigment ink.
[0004]
In the case of using pigment ink, in the high-density portion of the black image of the pigment ink, pure black is difficult to appear, and it may appear bluish or reddish. It was also found that the obtained image density was insufficient, and in addition, in a specific portion of the image, when the image was touched, an image defect due to sweat or oil of the hand occurred. The image defect here means that if you touch the image with a sweaty hand, the density will increase only at the touched part, and even if you wipe it, the increase in the density will not be eliminated, and the surrounding image that is not touched will be strange. This is a prominent problem. This phenomenon is particularly remarkable in a region where the amount of black ink applied is large.
[0005]
Although the cause of the above-described problems specific to the pigment ink is not clear, it is considered that one of the causes is that sufficient resin is not applied to the pigment in the pigment ink due to printing characteristics and ink storability. .
[0006]
To solve the above problem, a method has been disclosed in which an overcoat liquid having a film forming ability is applied to a specific portion of an image having a large amount of ink (for example, see Patent Document 1). This can be interpreted as supplying the insufficient resin from the second ink. However, in the disclosed technical content, the drying property is insufficient and high-speed printing suitability cannot be obtained. This is thought to be due to the use of a resin having a film-forming property at room temperature. In addition, the effect on the above-mentioned problem is insufficient. This is presumed to be due to insufficient mixing of the pigment of the pigment ink image and the film-forming component in the overcoat liquid, and the pigment is not sufficiently covered with the resin. Further, there is a case where the gloss of the image portion is too high, and a difference in gloss from a white background occurs, which is a problem.
[0007]
On the other hand, a technique of discharging a liquid containing a resin onto a pigment ink print image and heating the image with a heater or the like is disclosed (for example, see Patent Document 2). The effects on the above problems are also insufficient. This is presumed to be due to insufficient mixing of the pigment in the pigment ink image and the film-forming component in the overcoat liquid, as described above.
[0008]
On the other hand, JP-A-59-222381, JP-A-4-21446, JP-A-10-315448, JP-A-11-5362 and JP-A-11-192775 disclose thermoplastic organic polymer particles on the outermost layer of a recording medium. After recording an image, the thermoplastic organic polymer particles are melted and formed into a film, and as a result, a polymer protective film is formed, thereby improving the water resistance, weather resistance, and imparting gloss to the image. However, these recording media have insufficient ink absorption speed, and lack high-speed printing suitability.
[0009]
Furthermore, a certain amount of inorganic fine particles is added to a thermoplastic resin-containing layer to improve ink absorbency, and printing with pigment ink is disclosed (for example, see Patent Documents 3 to 5). These are interpreted as supplying the insufficient resin from the recording medium.However, in order to ensure high-speed ink absorption as described above, when a certain amount of inorganic fine particles is added to the thermoplastic resin-containing layer, the thermoplastic resin is added. Since the ratio decreases, sufficient resin for the pigment of the pigment ink image is not provided depending on the ratio, and the effect on the above problem may be insufficient.
[0010]
Also, JP-A-2002-121440 and JP-A-2002-144696 disclose methods of applying a polymer fine particle liquid after printing with an oil-based dye ink and a water-based dye ink, respectively, and further forming a film by heating. However, there is no description of printing with pigment ink, and there is no mention of the above-mentioned image defect due to sweat or oil. Further, in these, the polymer fine particle liquid is applied to the entire surface of the recorded image, and the drying load of the polymer fine particle liquid is large.
[0011]
[Patent Document 1]
JP, 2002-144551, A (claim)
[0012]
[Patent Document 2]
WO 00/06390 pamphlet
[0013]
[Patent Document 3]
Japanese Patent Application Laid-Open No. 2002-234246 (Claims)
[0014]
[Patent Document 4]
JP, 2002-234248, A (Claims)
[0015]
[Patent Document 5]
JP-A-2002-234256 (Claims)
[0016]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and a first object is to provide an inkjet image forming method capable of obtaining a high maximum density, and a second object is to provide a pure black having no reddish or blue tint. A third object of the present invention is to provide a method for forming an ink-jet image capable of providing a pigment image with improved image defects due to sweat or oil from the hands. A fourth object is to provide an ink jet image forming method having high gloss and improved in the occurrence of bronzing, and a fifth object is to provide an ink jet image forming method having improved scratch resistance. A sixth object is to provide an ink jet image forming method capable of providing a pigment image having a small difference in gloss in an image, and a seventh object is to provide a high-speed printing Also to provide a small ink jet image forming method of the image quality degradation.
[0017]
[Means for Solving the Problems]
The above object of the present invention is achieved by the following configurations.
[0018]
1. In a method of printing an image on an inkjet recording medium using a pigment ink, and an inkjet image forming method of forming an image through a step of heating and pressurizing the formed image, an image area having a density of 1.0 or more is formed. An ink jet image forming method comprising applying a liquid containing a resin and containing substantially no colorant to at least a part thereof.
[0019]
2. 2. The method according to claim 1, wherein the resin is an aqueous resin emulsion.
[0020]
3. 3. The inkjet image forming method according to claim 1, wherein at least one of the pigment inks has a resin content solid content in the pigment ink less than the pigment solid content.
[0021]
4. The inkjet recording medium has two or more ink absorbing layers on a support, and a surface layer which is an ink absorbing layer located farthest from the support contains a thermoplastic resin. The inkjet image forming method according to any one of Items 1 to 3.
[0022]
5. 5. The inkjet image forming method according to claim 4, wherein the surface layer further contains inorganic fine particles.
[0023]
The present inventors have made intensive studies on the above problems, and as a result, formed an image through a process of printing an image on an inkjet recording medium using a pigment ink and a process of heating and pressing the formed image. In the inkjet image forming method, a high maximum density can be obtained by applying a liquid containing a resin and containing substantially no colorant to at least a part of an image area having a density of 1.0 or more. It can reproduce pure black without taste and bluish, improves image defects due to hand sweat and oil, has high gloss, improves bronzing resistance and scratch resistance, has little difference in gloss in the image, and has high image quality even at high speed printing. It has been found that a small number of jet images can be obtained, and the present invention has been reached.
[0024]
Further, an aqueous resin emulsion is used as the resin, at least one of the pigment inks is such that the solid content of the resin in the pigment ink is smaller than the pigment solid content, and the ink jet recording medium to be used has two or more layers on the support. The surface of the ink absorption layer located farthest from the support is a thermoplastic resin, and the surface layer further contains inorganic fine particles. It has been found that the effect is exhibited.
[0025]
Hereinafter, details of the present invention will be described.
One feature of the inkjet image forming method of the present invention is that a pigment ink is used as the ink.
[0026]
As the pigment ink used for image formation, a water-based ink composition, an oil-based ink composition, a solid (phase change) ink composition, or the like can be used, and the water-based ink composition (for example, 10% by mass per ink total mass) can be used. The above-mentioned water-based inkjet recording liquid containing water, etc.) can be particularly preferably used.
[0027]
As a colorant, a pigment is characteristically used from the viewpoint of image storability. As the pigment in the pigment ink, organic pigments such as insoluble pigments and lake pigments, and carbon black can be preferably used.
[0028]
Examples of the insoluble pigment include, but are not particularly limited to, for example, azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine, thiazine, Dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole and the like are preferred.
[0029]
Specific pigments that can be preferably used include the following pigments. Examples of magenta or red pigments include C.I. I. Pigment Red 2, C.I. I. Pigment Red 3, C.I. I. Pigment Red 5, C.I. I. Pigment Red 6, C.I. I. Pigment Red 7, C.I. I. Pigment Red 15, C.I. I. Pigment Red 16, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 53: 1, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 123, C.I. I. Pigment Red 139, C.I. I. Pigment Red 144, C.I. I. Pigment Red 149, C.I. I. Pigment Red 166, C.I. I. Pigment Red 177, C.I. I. Pigment Red 178, C.I. I. Pigment Red 222 and the like.
[0030]
Examples of orange or yellow pigments include C.I. I. Pigment Orange 31, C.I. I. Pigment Orange 43, C.I. I. Pigment Yellow 12, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 15, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 93, C.I. I. Pigment Yellow 94, C.I. I. Pigment Yellow 138 and the like.
[0031]
Examples of green or cyan pigments include C.I. I. Pigment Blue 15, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 60, C.I. I. Pigment Green 7 and the like.
[0032]
These pigments may use a pigment dispersant as needed.Examples of pigment dispersants that can be used include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, and sulfosuccinates. , Naphthalene sulfonate, alkyl phosphate, polyoxyalkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, amine oxide, etc. Or an activator of two or more selected from styrene, styrene derivatives, vinylnaphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives Block copolymer comprising a body, a random copolymer and can be exemplified salts thereof.
[0033]
The method for dispersing the pigment is not particularly limited, and examples thereof include various methods such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, and a paint shaker. Can be used.
[0034]
For the purpose of removing the coarse particles of the pigment dispersion according to the present invention, it is also preferable to use a centrifugal separator or use a filter.
[0035]
The average particle size of the pigment in the pigment ink is selected in consideration of the stability in the ink, image density, glossiness, light resistance, and the like. It is preferable to select the particle size also from the viewpoint of improving the texture. In the present invention, the reason why the gloss and the texture are improved is not clear, but it is presumed that the pigment is related to the state where the thermoplastic fine particles are dispersed in the molten film in the image. For high-speed processing, the thermoplastic fine particles must be melted into a film in a short time, and the pigment must be sufficiently dispersed in the film. At this time, it is presumed that the surface area of the pigment has a great effect, and therefore, an optimum region exists in the average particle size.
[0036]
The average particle size of the pigment particles contained in the pigment ink used in the present invention is preferably 300 nm or less, more preferably 30 to 200 nm, and particularly preferably 30 to 150 nm.
[0037]
The water-based ink composition, which is a preferred form of the pigment ink, preferably uses a water-soluble organic solvent in combination.
[0038]
Examples of the water-soluble organic solvent include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc.), and polyhydric alcohols (Eg, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc.), polyhydric alcohol ethers (Eg, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Tylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol Monobutyl ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, etc.), amines (for example, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine) , Ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc., amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.) ), Heterocycles (eg, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, etc.), sulfoxides (eg, dimethyl sulfoxide) , Sulfones (eg, sulfolane), urea, acetonitrile, acetone and the like. Preferred water-soluble organic solvents include polyhydric alcohols. Further, it is particularly preferable to use a polyhydric alcohol and a polyhydric alcohol ether in combination.
[0039]
The water-soluble organic solvents may be used alone or in combination of two or more. The total amount of the water-soluble organic solvent in the ink is 5 to 60% by mass, preferably 10 to 35% by mass.
[0040]
The pigment ink used in the present invention preferably contains an acetylene-based surfactant. As the acetylene-based surfactant, acetylene diol and its ethylene oxide adduct are preferable.
[0041]
As acetylenic diol and its ethylene oxide adduct, Surfynol 82, Surfynol 104, Surfynol 440, Surfynol 465, Surfynol 485 and the like manufactured by Air Products are preferably used.
[0042]
The ink composition contains thermoplastic fine particles, a viscosity adjuster, a surface tension adjuster, and a ratio according to the purpose of improving ejection stability, compatibility with a print head or an ink cartridge, storage stability, image storability, and other various performances. A resistance adjuster, a film-forming agent, a dispersant, a surfactant, an ultraviolet absorber, an antioxidant, an anti-fading agent, a sunscreen, a rust preventive, and the like can be appropriately added.
[0043]
In particular, it is preferable to add thermoplastic fine particles in order to obtain the effects of the present invention. As the thermoplastic fine particles, those described in the description of the thermoplastic resin or the fine particles that can be added to the surface layer of the recording medium can be used. In particular, it is preferable to use an ink which does not cause viscosity increase or precipitation even when added to the ink. The average particle size of the thermoplastic fine particles is preferably 0.5 μm or less, more preferably 0.2 to 2 times the average particle size of the pigment in the ink, from the viewpoint of stability. The thermoplastic fine particles to be added preferably melt and soften in the range of 50 ° C to 200 ° C.
[0044]
The viscosity of the ink composition during flight is preferably 40 mPa · s or less, more preferably 30 mPa · s or less.
[0045]
The surface tension of the ink composition during flight is preferably 20 mN / m or more, and more preferably 30 to 45 mN / m.
[0046]
The pigment solids concentration in the ink can be selected in the range of 0.1 to 10%. In order to obtain a photographic image, it is preferable to use so-called dark and light inks in which the pigment solids concentration is changed, respectively, yellow, magenta, It is particularly preferable to use cyan and black light and dark inks, respectively. It is also preferable from the viewpoint of color reproducibility to use special color inks such as red, green, and blue as required.
[0047]
In the pigment ink described above, in the present invention, a pigment ink dispersed using a polymer dispersant, a self-dispersion pigment such as partially oxidizing the pigment surface or modifying the surface with an ionic pigment derivative or the like is used. Ink or a pigment ink containing a resin in addition to the dispersant can be preferably used. In the present invention, after printing, the amount of resin that can be imparted by a liquid containing the resin according to the present invention and containing substantially no colorant can be adjusted as needed, so that it is also suitable for applying a self-dispersion pigment. I have.
[0048]
When a resin is added as a dispersant or an additive to the pigment ink, the total amount of the resin is preferably smaller than the solid content of the pigment. When the amount of the resin is large, it affects the ink absorbency, hinders drying of the ink solvent containing water from the image, and when applying a liquid containing substantially no colorant containing the resin according to the present invention, This is because the influence is very large.
[0049]
Further, in the pigment ink according to the present invention, it is preferable to add a small amount of a known dye in view of the effect of the present invention, but if a large amount is added, the image storability deteriorates. 1% by mass or less, and more preferably 0.5% by mass or less. The color of the dye to be added is preferably the same as the color of the pigment of the main component, but may be different depending on the case. In particular, it is a preferred embodiment to add a dye to the black ink.
[0050]
In the inkjet image forming method of the present invention, after printing a pigment ink, a liquid containing a resin and containing substantially no colorant is applied to at least a part of a region having an image density of 1.0 or more. Is one of the features.
[0051]
In the present invention, at least a part of the region where the image density is 1.0 or more refers to an image area of 5% or more in the image portion where the reflection density of the image formed by printing the pigment ink is 1.0 or more. It is preferable that the liquid is coated on all the image portions, preferably 25% or more, more preferably 50% or more, and particularly preferably.
[0052]
The term "liquid substantially free of a colorant" as used in the present invention means that the colorant such as the above-described pigment or dye is not contained at all, but in some cases, less than 0.1% by mass of the colorant. It does not exclude the inclusion of agents.
[0053]
The medium used as the liquid containing the resin according to the present invention and containing substantially no colorant is preferably an aqueous medium in terms of environment, but may be an organic solvent depending on the use. The resin may be soluble in the medium, may be a dispersion, or may be partially dissolved. Dispersions are preferred in view of the absorbency and drying properties of this liquid.
[0054]
Hereinafter, a liquid containing an aqueous resin and containing substantially no colorant will be described as a representative example.
[0055]
A liquid containing a resin and substantially not containing a colorant (hereinafter referred to as a liquid according to the present invention) contains a resin in an amount of 0.1 to 10% by mass (solid content) and a water-soluble solvent in an amount of 1 to 50% by mass, If necessary, each functional compound such as a surfactant, an ultraviolet absorber, an antioxidant, and an antioxidant may be contained. Furthermore, the liquid according to the present invention does not substantially contain a colorant, which means that the liquid does not substantially have a function as a recording liquid, and for other purposes, for example, checking the remaining ink amount. It may be slightly tinted, for example, to adjust the color tone of a white background when printing on a white background, or to check the dischargeability.
[0056]
Examples of the resin that can be used as the liquid according to the present invention include a water-soluble binder and a resin emulsion. In the present invention, a resin emulsion is preferable.
[0057]
Examples of the water-soluble binder include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyurethane, dextran, dextrin, carrageenan (κ, ι, λ, etc.), agar, pullulan, and water-soluble polyvinyl butyral , Hydroxyethyl cellulose, carboxymethyl cellulose and the like. Two or more of these water-soluble resins can be used in combination.
[0058]
The water-soluble resin preferably used in the present invention is polyvinyl alcohol. The polyvinyl alcohol preferably used in the present invention includes, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, modified polyvinyl such as polyvinyl alcohol having a cation-modified terminal or an anion-modified polyvinyl alcohol having an anionic group. Also includes alcohol.
[0059]
The resin emulsion that can be used in the present invention is a state in which a polymer is dispersed in water. Preferred examples of the monomer include acrylonitrile, styrene, acrylates (acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, -Hydroxyethyl acrylate, 2-ethylhexyl acrylate, glycidyl acrylate, methacrylic acid, methyl methacrylate, butyl methacrylate), vinyl acetate, polyvinyl alcohol, butadiene, vinyl chloride, polyvinylidene chloride, and a combination of two or more of these monomers. Copolymers are preferred. Further, saponified vinyl acetate incorporated into the copolymer, a part or all of vinyl acetate is converted to a vinyl alcohol, a thermoplastic resin, polyurethane, silicone-acrylic copolymer and the like are preferably used, and polyester And a polyurethane resin can also be used.
[0060]
In the present invention, the resin emulsion is preferably one that melts or forms a film in a drying or heating step, and has a Tg of 200 ° C. or lower, preferably 150 ° C. or lower, more preferably 130 ° C. or lower. Although those having a Tg of room temperature or lower are applicable, those having a temperature higher than room temperature are preferable from the viewpoint of ink absorption. The most preferred Tg is 50-130 ° C. Also, a plurality of types of resin emulsions having different Tg can be used.
[0061]
The particle size of the resin emulsion is preferably 500 nm or less, more preferably 150 nm or less.
[0062]
Examples of the water-soluble solvent that can be used in the liquid according to the present invention include the same water-soluble organic solvents as those described for the pigment ink.
[0063]
Next, a method for applying a liquid according to the present invention will be described.
The liquid according to the present invention is emitted from a dedicated recording head separate from the pigment ink and printed. The dedicated recording head may be mounted on the same carriage as the pigment ink, or may be mounted on a separate carriage. However, a method in which the dedicated recording head is mounted on the same carriage as the pigment ink is preferable from the viewpoint of reducing the size of the apparatus.
[0064]
In the present invention, the printing area of the liquid according to the present invention is characterized in that printing is performed on at least a part of an image area having a density of 1.0 or more. Depending on the type of the pigment ink, the type of the ink jet recording medium, or the heating and pressurizing conditions, by applying the liquid according to the present invention only to the higher density part, a sufficient effect may be exerted, and depending on the image characteristics, May be applied to at least a part of an image area having a density of 1.5 or more or at least a part of an image area having a density of 2 or more. In the present invention, it is preferable from the viewpoints of printing time, drying load, and running cost to limit the liquid ejection region according to the present invention to a high density portion.
[0065]
Further, in the present invention, it is not necessary to apply the liquid according to the present invention to all color images at the same time, and in particular, black ink, cyan ink, and yellow ink are mainly used (at least 50% of the total ink amount). It is preferable to emit the liquid according to the present invention to the image region that is dripped, since a great target effect can be obtained. In particular, it is preferable to emit light to an image area where black ink is mainly applied.
[0066]
In the present invention, the order in which the pigment ink and the liquid according to the present invention are emitted is not particularly limited. .
[0067]
Next, the ink jet recording medium according to the present invention will be described.
The ink jet recording medium according to the present invention has two or more ink absorbing layers on a support, and the surface layer which is the ink absorbing layer located farthest from the support preferably contains a thermoplastic resin. .
[0068]
As the thermoplastic resin that can be used in the surface layer according to the present invention, for example, polycarbonate, polyacrylonitrile, polystyrene, polyacrylic acid, polymethacrylic acid, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester, polyamide, Examples thereof include polyethers, copolymers thereof and salts thereof. Among them, styrene-acrylate copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acrylate copolymer, ethylene-vinyl acetate copolymer Preferred are polymers, ethylene-acrylate copolymers, and SBR latex. The thermoplastic resin may be used by mixing a plurality of polymers having different monomer compositions, particle diameters, and degrees of polymerization.
[0069]
In selecting a thermoplastic resin, consideration should be given to ink absorptivity, glossiness of an image after a post-processing step by heating and pressurizing, image fastness, and releasability.
[0070]
Regarding the ink absorbency, when the particle size of the thermoplastic fine particles is less than 0.05 μm, the separation of the pigment particles from the pigment solvent in the pigment ink and the ink solvent becomes slow, which causes a decrease in the ink absorption speed. On the other hand, if it exceeds 10 μm, it is not preferable from the viewpoints of adhesiveness to the solvent absorbing layer adjacent to the ink receiving layer when coated on the support and film strength of the ink jet recording medium after coating and drying. For this purpose, the thermoplastic resin particle diameter is preferably 0.05 to 10 μm, more preferably 0.1 to 5 μm. More preferably, it is 0.1 to 1 μm.
[0071]
Further, as a criterion for selecting a thermoplastic resin, a glass transition point (Tg) can be cited. If the Tg is lower than the coating and drying temperature, for example, the coating and drying temperature at the time of production of the recording medium is already higher than the Tg, and the voids due to the thermoplastic fine particles through which the ink solvent permeates disappear.
[0072]
When the Tg is higher than the temperature at which the support is denatured by heat, a fixing operation at a high temperature is required to form a melt film after inkjet recording with the pigment ink. Sex and the like become problems. The preferred Tg of the thermoplastic fine particles is from 50 to 150 ° C. The minimum film formation temperature (MFT) is preferably 50 to 150C.
[0073]
The thermoplastic fine particles are preferably dispersed in an aqueous system from the viewpoint of environmental suitability, and in particular, an aqueous latex obtained by emulsion polymerization is preferable. At this time, a type obtained by emulsion polymerization using a nonionic dispersant as an emulsifier is a form that can be preferably used.
[0074]
The thermoplastic fine particles used preferably have a small amount of residual monomer components from the viewpoint of odor and safety, and are preferably 3% or less, more preferably 1% or less, and particularly preferably 0.1% or less, based on the solid content of the polymer. 1% or less is preferable.
[0075]
In the surface layer according to the present invention, it is preferable to use inorganic fine particles together with the thermoplastic resin.
[0076]
Examples of the inorganic fine particles that can be used in the present invention include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, and zinc sulfide. , Zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide, etc. Examples thereof include white inorganic pigments.
[0077]
As the inorganic fine particles, it is preferable to use solid fine particles selected from silica and alumina or alumina hydrate, and silica is more preferable.
[0078]
As the silica, silica synthesized by an ordinary wet method, colloidal silica, silica synthesized by a gas phase method, or the like is preferably used, and fine particle silica particularly preferably used in the present invention is colloidal silica or a gas phase method. Highly porosity is obtained from the finely-divided silica synthesized by the gas phase method. The alumina or alumina hydrate may be crystalline or amorphous, and may have any shape such as irregular particles, spherical particles, and acicular particles.
[0079]
The inorganic fine particles preferably have a particle size of 100 nm or less. For example, in the case of the above-mentioned fumed silica, the average particle diameter of the primary particles of the inorganic fine particles dispersed in the state of the primary particles (the particle diameter in the dispersion state before coating) is preferably 100 nm or less. It is more preferably 4 to 50 nm, most preferably 4 to 20 nm.
[0080]
As the most preferably used silica synthesized by a gas phase method having an average primary particle size of 4 to 20 nm, for example, Aerosil manufactured by Nippon Aerosil Co., Ltd. is commercially available. The vapor-phase-process fine-particle silica can be relatively easily dispersed into primary particles by suction-dispersing in water using, for example, a jet stream inductor mixer manufactured by Mitamura Riken Kogyo KK.
[0081]
The surface layer according to the present invention may appropriately contain a water-soluble binder in addition to the above configuration.
[0082]
Examples of the water-soluble binder include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyurethane, dextran, dextrin, carrageenan (κ, ι, λ, etc.), agar, pullulan, and water-soluble polyvinyl butyral , Hydroxyethyl cellulose, carboxymethyl cellulose and the like. Two or more of these water-soluble resins can be used in combination.
[0083]
The water-soluble resin preferably used in the present invention is polyvinyl alcohol. The polyvinyl alcohol preferably used in the present invention includes, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, modified polyvinyl such as polyvinyl alcohol having a cation-modified terminal or an anion-modified polyvinyl alcohol having an anionic group. Also includes alcohol.
[0084]
In the present invention, it is preferable that the surface layer has a configuration containing inorganic fine particles and a thermoplastic resin.
[0085]
1) High ink absorption speed, low image quality deterioration such as beading and color bleed, and high-speed printability
2) High image surface strength
3) It is hard to cause fusing by overlapping when storing images.
4) Excellent surface layer coating productivity
5) Writable
In this case, the solid content mass ratio between the thermoplastic resin and the inorganic fine particles in the surface layer is preferably determined individually depending on the thermoplastic resin, the inorganic fine particles and other additives, but in the present invention, the thermoplastic resin (B ) And the filler (F) (B / F) is preferably 2/8 to 8/2, more preferably 3/7 to 7/3, and still more preferably 4/6 to 6/3. / 4.
[0086]
The surface layer according to the present invention may contain a cationic water-soluble polymer having a quaternary ammonium base in the molecule. ² The amount is usually 0.1 to 10 g, preferably 0.2 to 5 g.
[0087]
The thickness of the surface layer according to the present invention is preferably 3 to 15 μm.
In the ink jet recording medium of the present invention, it is preferable to provide an ink absorbing layer for absorbing the ink solvent between the support and the surface layer.
[0088]
The ink absorbing layer of the recording medium is roughly classified into a swelling type and a void type.
As the swelling type, a hydrophilic binder, for example, gelatin, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide, or the like, which is applied alone or in combination and used as an ink absorbing layer can be used.
[0089]
The void type is obtained by mixing and applying fine particles and a hydrophilic binder, and is particularly preferably glossy. As the fine particles, alumina or silica is preferable, and particularly, silica using silica having a particle size of 0.1 μm or less is preferable. As the hydrophilic binder, for example, those using gelatin, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide or the like alone or in combination are preferable.
[0090]
In order to provide suitability for continuous or high-speed printing, it is suitable for the recording medium to have a high ink absorption rate. In this regard, the void type can be particularly preferably used.
[0091]
Hereinafter, the void-type ink absorbing layer (also referred to as a void layer) will be described in more detail.
The void layer is formed mainly by soft aggregation of the hydrophilic binder and the inorganic fine particles. Conventionally, various methods for forming voids in a film are known. For example, a uniform coating solution containing two or more polymers is applied on a support, and these polymers are phase-separated from each other in a drying process. A method of forming voids by applying a coating liquid containing solid fine particles and a hydrophilic or hydrophobic binder onto a support, drying the ink, and immersing the ink jet recording medium in a liquid containing water or a suitable organic solvent. A method of forming voids by dissolving solid fine particles by applying a coating solution containing a compound having a property of foaming during film formation, and then forming a void in the film by foaming the compound in a drying process, Coating a coating solution containing porous solid fine particles and a hydrophilic binder on a support, forming voids in the porous fine particles or between the fine particles, approximately equal to or more than the hydrophilic binder The coating solution containing the solid particles and or particulate oil and a hydrophilic binder having a volume and coated on a support, and a method of making an air gap between the solid particles are known. In the present invention, it is particularly preferable that the void layer is formed by including various inorganic solid fine particles having an average particle diameter of 100 nm or less.
[0092]
As the inorganic fine particles used for the above purpose, those similar to the inorganic fine particles used in the above-mentioned surface layer can be used.
[0093]
Examples of the hydrophilic binder include the same compounds as the water-soluble binder described in the above-mentioned surface layer.
[0094]
The amount of the inorganic fine particles used in the ink absorbing layer greatly depends on the required ink absorption capacity, the porosity of the void layer, the type of the inorganic fine particles, and the type of the water-soluble resin. ² Per hit, it is usually 5 to 30 g, preferably 10 to 25 g.
[0095]
The mass ratio of the inorganic fine particles to the water-soluble resin used in the ink absorbing layer is usually from 2: 1 to 20: 1, and particularly preferably from 3: 1 to 10: 1.
[0096]
The ink-absorbing layer may contain a cationic water-soluble polymer having a quaternary ammonium base in the molecule. ² The amount is usually 0.1 to 10 g, preferably 0.2 to 5 g.
[0097]
In the void layer, the total amount of voids (void volume) is 1 m of the recording medium. ² Preferably, the volume is 20 ml or more. Void volume is 20ml / m ² If the amount is less than the ink amount at the time of printing, the ink absorption is good, but if the amount of ink is large, the ink is not completely absorbed, and the image quality is reduced, and the drying property is delayed. Problems are likely to occur.
[0098]
As another type of void type, besides forming an ink solvent absorbing layer using inorganic fine particles, a polyurethane resin emulsion is used in combination with a water-soluble epoxy compound and / or acetoacetylated polyvinyl alcohol, and an epichlorohydrin polyamide resin is further used in combination. The ink solvent absorbing layer may be formed using the applied coating liquid.
[0099]
In the present invention, the average porosity of the entire ink absorbing layer of the inkjet recording medium is preferably 40 to 70%, or the porosity of the above-described surface layer is preferably 30 to 70%.
[0100]
Next, the support used in the ink jet recording medium according to the present invention will be described.
[0101]
As the support used in the present invention, a support conventionally used for an ink jet recording medium, for example, a paper support such as plain paper, art paper, coated paper and cast coated paper, a plastic support, and polyolefin on both sides. A coated paper support or a composite support obtained by laminating these may be used, but from the viewpoint of further exhibiting the effects of the present invention, it is preferable to use a water-impermeable support.
[0102]
Examples of the water-impermeable support used in the present invention include a plastic resin film support and a support in which both surfaces of paper are covered with a plastic resin film. Examples of the plastic resin film support include a polyester film, a polyvinyl chloride film, a polypropylene film, a cellulose triacetate film, a polystyrene film, and a laminated film support thereof. These plastic resin films may be transparent or translucent.
[0103]
In the present invention, a particularly preferred support is a support in which both sides of paper are coated with a plastic resin, and a most preferred support is a support in which both sides of paper are coated with a polyolefin resin.
[0104]
Hereinafter, a support in which both surfaces of a paper, which is a particularly preferred support in the present invention, are coated with a polyolefin resin will be described.
[0105]
The paper used for the support of the present invention is made from wood pulp as a main raw material and, if necessary, using synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester in addition to wood pulp. As the wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, and NUKP can be used, but it is preferable to use LBKP, NBSP, LBSP, NDP, and LDP which contain a large amount of short fibers. However, the ratio of LBSP and / or LDP is preferably 10 to 70%. As the pulp, chemical pulp (sulfate pulp or sulfite pulp) having a small amount of impurities is preferably used, and pulp having improved whiteness by performing a bleaching treatment is also useful.
[0106]
In paper, for example, higher fatty acids, sizing agents such as alkyl ketene dimer, white pigments such as calcium carbonate, talc, titanium oxide, paper strength enhancers such as starch, polyacrylamide, polyvinyl alcohol, fluorescent whitening agents, polyethylene A water retention agent such as glycols, a dispersant, a softening agent such as quaternary ammonium, and the like can be appropriately added.
[0107]
The freeness of the pulp used for papermaking is preferably 200 to 500 ml according to the CSF specification, and the sum of the 24 mesh residue and the 42 mesh residue whose fiber length after beating is specified in JIS P 8207 is 30 to 50. 70% is preferred. In addition, it is preferable that the 4 mesh residue is 20% or less.
[0108]
The basis weight of the paper is preferably from 50 to 250 g, and particularly preferably from 70 to 200 g. The thickness of the paper is preferably 50 to 210 μm.
[0109]
The paper can also be calendered at the papermaking stage or after papermaking to provide high smoothness. Paper density is 0.7-1.2g / cm ³ (JIS P 8118) is common. Further, the rigidity of the base paper is preferably from 20 to 200 g under the conditions specified in JIS P 8143.
[0110]
A surface sizing agent may be applied to the paper surface, and the same sizing agent as can be added to the base paper can be used as the surface sizing agent.
[0111]
The pH of the paper is preferably 5 to 9 when measured by the hot water extraction method specified in JIS P 8113.
[0112]
Next, the polyolefin resin covering both sides of the paper will be described.
Examples of the polyolefin resin used for this purpose include polyethylene, polypropylene, polyisobutylene, and polyethylene. Polyolefins such as a copolymer mainly composed of propylene are preferable, and polyethylene is particularly preferable.
[0113]
Hereinafter, particularly preferred polyethylene will be described.
The polyethylene that covers the front and back surfaces of the paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but other LLDPE, polypropylene, and the like can also be partially used.
[0114]
In particular, the polyolefin layer on the coating layer side preferably has improved opacity and whiteness by adding rutile or anatase type titanium oxide therein. The titanium oxide content is generally 1 to 20%, preferably 2 to 15%, based on the polyolefin.
[0115]
In the polyolefin layer, a color pigment having high heat resistance and a fluorescent whitening agent for adjusting a white background can be added.
[0116]
Examples of the coloring pigment include ultramarine, navy blue, cobalt blue, phthalocyanine blue, manganese blue, cerulean, tungsten blue, molybdenum blue, anthraquinone blue, and the like. Examples of the fluorescent whitening agent include the same compounds as the fluorescent whitening agent used in the ink absorbing layer.
[0117]
The amount of polyethylene used on the front and back of the paper is selected so as to optimize the thickness of the ink absorbing layer and the curl in low and high humidity after providing the back layer. Is 15 to 50 μm on the ink absorbing layer side and 10 to 40 μm on the back layer side. The ratio of the front and back polyethylene is preferably set so as to adjust the curl that changes depending on the type and thickness of the ink absorbing layer, the thickness of the inner paper, and the like. It is approximately 3/1 to 1/3.
[0118]
Further, the polyethylene-coated paper support preferably has the following characteristics (1) to (7).
[0119]
(1) The tensile strength is preferably 19.6 to 294 N in the vertical direction and 9.8 to 196 N in the horizontal direction at the strength specified by JIS P 8113.
[0120]
(2) The tear strength is preferably 0.20 to 2.94 N in the longitudinal direction and 0.098 to 2.45 N in the horizontal direction, as defined by JIS P 8116.
[0121]
(3) The compression modulus is 9.8 kN / cm ² Is preferred.
(4) The opacity is preferably 80% or more, particularly preferably 85 to 98%, as measured by the method specified in JIS P 8138.
[0122]
(5) Whiteness is L defined in JIS Z 8727 ^* , A ^* , B ^* Is L ^* = 80-96, a ^* = -3 to +5, b ^* = −7 to +2.
[0123]
(6) The Clark stiffness is 50 to 300 cm in the direction in which the recording medium is conveyed. ³ / 100 is preferred.
[0124]
(7) The moisture in the base paper is preferably 4 to 10% based on the middle paper.
(8) The glossiness (75-degree specular glossiness) on the surface on which the ink absorbing layer is provided is preferably 10 to 90%.
[0125]
The printer used in the inkjet image forming method of the present invention is not particularly limited as long as it has a recording medium storage section, a transport section, an ink cartridge, and an inkjet print head as a commercially available printer. When using a series of printer sets consisting of a recording medium storage section, a transport section, an inkjet print head, a cutting section, and a press section, a heating section as needed, and a recording print storage section, inkjet printing is used commercially. Useful for
[0126]
The recording head may be any of a piezo system, a thermal system, and a continuous system, but the piezo system is preferable from the viewpoint of stability with pigment ink.
[0127]
Next, the heat and pressure treatment steps according to the inkjet image forming method of the present invention will be described.
[0128]
The inkjet image forming method of the present invention includes a step of heating and pressurizing after ejecting a liquid containing a pigment ink and the resin according to the present invention and containing substantially no colorant to the inkjet recording medium having the above-described configuration. The heat and pressure treatment conditions are preferably a pressure of 0.5 to 10 MPa and a temperature condition of 50 to 150 ° C., more preferably 0.5 to 5 MPa. And a temperature condition of 70 to 130 ° C.
[0129]
The heating / pressing method that can be used in the present invention is not particularly limited, but a pair of heating / pressing rollers, a pair of heating / pressing belts, or a heating / pressing belt on the surface contacting the image recording surface, and a back surface It is preferable to use a heating / pressing device in which a member in contact with the side includes a holding roller.
[0130]
As the heating / pressing roller, a metal roller made of metal or a metal core having a coating layer made of an elastic material and a surface layer (also referred to as a release layer) formed as needed around a metal core, The core is made of, for example, a cylindrical body made of iron, aluminum, SUS, or the like. A coating layer is provided on the surface of the cored bar. The coating layer is particularly preferably a silicone resin having releasability, for example, a silicone resin prepared using a curable silicone such as a solvent addition type or a condensation curable silicone. Particularly preferred is a solvent addition type silicone.
[0131]
The solvent-added silicone described above is obtained by reacting a linear methylvinylpolysiloxane having a vinyl group with methylhydrogenpolysiloxane at both ends or at both ends and in the chain in the presence of a platinum-based catalyst. can get.
[0132]
Specific examples of the solvent addition type silicone include, for example, KS-887, KS-779H, KS-778, KS-835, X-62-2456, X-62-2494, X-62-2461 manufactured by Shin-Etsu Silicone Co., Ltd. , KS-3650, KS-3655, KS-3600, KS-847, KS-770, KS-770L, KS-776A, KS-856, KS-775, KS-830, KS-830E, KS-839, X -62-2404, X-62-2405, KS-3702, X-62-2232, KS-3503, KS-3502, KS-3703, KS-5508 and the like.
[0133]
As a specific example of the condensation-curable silicone, for example, silicones such as KS-881, KS-882, KS-883, X-62-9490, and X-62-9028 manufactured by Shin-Etsu Silicone Co., Ltd. are preferably used.
[0134]
In addition, a heating element is incorporated inside one of the metal cores of the metal roller, and by passing a recording medium between the rollers, heat treatment and pressure treatment can be performed simultaneously, or if necessary, The recording medium may be heated using two heating rollers. As the heat source, for example, a heating element made of a halogen lamp heater, a ceramic heater, a nichrome wire, or the like is built in the heating roller.
[0135]
As a belt base material used for the heating and pressurizing device, a seamless nickel electro-brass is preferable, and a thickness of the base material is preferably 10 to 100 μm. Further, as a material of the base material, aluminum, iron, polyethylene, or the like can be used in addition to nickel.
[0136]
Regardless of whether the substrate is a roller or a belt, the thickness of the silicone resin layer is preferably 1 to 50 μm, more preferably 10 to 30 μm.
[0137]
In the present invention, in order to achieve the pressure (nip pressure) defined above, for example, a spring having a specific tension is provided at both ends of the pressure roller in consideration of the nip gap so that a desired nip pressure is obtained. You only have to select and install it. As the spring at this time, for example, a spring having a tension of 0.2 to 10 MPa can be selected and used according to the roller length.
[0138]
The method of measuring the nip pressure can be determined, for example, by dividing the force applied to the pressure roller by the nip area measured with a pressure-sensitive paper or the like, or sandwiching a pressure measurement paper made of a pressure-sensitive paper between the pressure rollers. The nip pressure can be obtained from the density of the pressure measurement paper by applying pressure. Examples of the pressure measurement paper include FPD301 (manufactured by Fuji Film Co., Ltd.) ultra-low pressure pressure-sensitive paper.
[0139]
When a heating and pressing roller or a heating and pressing belt is used, the conveying speed of the recording medium is preferably in the range of 1 to 15 mm / sec. This is preferable not only from the viewpoint of high-speed processing but also from the viewpoint of image quality.
[0140]
Next, an example of an apparatus that can be used in the image forming method of the present invention will be described.
FIG. 1 shows an example of an ink jet recording apparatus having a heating / pressing roller for performing a heating / pressing treatment which can be used in the present invention. FIG. 2 shows another example of an ink jet recording apparatus having a heating / pressing belt for performing a heating / pressing process which can be used in the present invention.
[0141]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.
[0142]
<< Preparation of recording medium >>
[Preparation of recording medium 1]
(Preparation of silica dispersion)
125 kg of fumed silica (QS-20 manufactured by Tokuyama Corporation) having an average primary particle size of about 0.012 μm was treated with nitric acid using nitric acid with a jet stream inductor mixer TDS manufactured by Mitamura Riken Kogyo Co., Ltd. Was adjusted to 2.5 at 620 L of pure water by suction at room temperature, and the total amount was made up to 694 L with pure water.
[0143]
Next, 69.4 L of the above silica dispersion was stirred into 18 L of an aqueous solution (pH = 2.3) containing 1.14 kg of the cationic polymer P-1, 2.2 L of ethanol and 1.5 L of n-propanol. Then, 7.0 L of an aqueous solution containing 260 g of boric acid and 230 g of borax was added, and 1 g of an antifoaming agent SN381 (manufactured by San Nopco) was added. This mixed solution was dispersed with a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd., and the total amount was adjusted to 97 L with pure water to prepare a silica dispersion.
[0144]
Embedded image

[0145]
(Preparation of lower layer coating solution 1)
While stirring 600 ml of the above silica dispersion at 40 ° C., the following additives were sequentially mixed to prepare a lower layer coating solution 1.
[0146]
Of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA203)
6% 10% aqueous solution
Of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA235)
185ml of 7% aqueous solution
Saponin (50% aqueous solution)
Pure water finished to 1000ml
(Preparation of coating solution 1 for surface layer)
While stirring an appropriate amount of water at 40 ° C., the following additives were sequentially mixed to prepare a surface layer coating solution 1.
[0147]
Thermoplastic resin (styrene-acrylic latex Tg 73 ° C, average particle size
0.9 μm, solid content 40%) 166 g
Of polyvinyl alcohol (Kuraray Industries, Ltd .: PVA235)
18ml of 7% aqueous solution
6.2 mg of antifoaming agent SN381 (manufactured by San Nopco Co., Ltd.)
Saponin (50% aqueous solution)
Pure water finished to 1000ml
After mixing each of the above additives, pure water was appropriately added so that the viscosity at 40 ° C. became 45 mPa · s, to prepare a coating solution 1 for a surface layer.
[0148]
(Preparation of recording medium 1)
The lower layer coating solution as a first layer from the support side on a paper support coated on both sides with polyethylene (thickness of 220 μm and 13% by mass of polyethylene relative to polyethylene in polyethylene on the ink absorbing layer surface) 1 was applied by a slide hopper, and then the surface layer coating solution 1 was applied thereon as a second layer by a slide hopper and dried to prepare a recording medium 1. The coating solution was applied by heating to 40 ° C., and immediately after coating, was cooled in a cooling zone maintained at 0 ° C. for 20 seconds, and then heated at 45 ° C. for 60 seconds in a wind of 25 ° C. (15% relative humidity). It is dried in a wind (relative humidity: 25%) for 60 seconds and then by a wind of 50 ° C. (relative humidity: 25%) for 60 seconds, and conditioned for 2 minutes in an atmosphere of 20 to 25 ° C. and a relative humidity of 40 to 60 ° C. The sample was wound up. The coating amount was controlled such that the lower layer had a dry film thickness of 30 μm and the surface layer had a dry film thickness of 10 μm. This recording medium 1 was processed into a roll shape having a roll width of 127 mm and a length of 100 m.
[0149]
[Preparation of recording medium 2]
In the production of the recording medium 1, the following coating liquid for surface layer 2 was used in place of the coating liquid for surface layer 1, and the coating liquid for lower layer 1 and the coating liquid for surface layer 2 were simultaneously layered so that the dry thickness of the surface layer was 7 μm. A recording medium 2 was produced in the same manner except that the coating was performed.
[0150]
(Preparation of Surface Layer Coating Solution 2)
The lower layer coating solution 1 used in the production of the recording medium 1 was stirred at 40 ° C., and a thermoplastic resin (styrene-acrylic latex Tg 73 ° C., average particle size 0.2 μm, solid content 40%) was added thereto. The surface layer coating liquid 2 was prepared by adding a solid content ratio of 50/50 / filler (silica) and appropriately adding pure water so that the viscosity became 45 mPa · s at 40 ° C.
[0151]
[Preparation of recording media 3 to 5]
In the production of the recording medium 2, recording media 3 to 5 were produced in the same manner except that the solid content ratio of the thermoplastic fine particles / filler (silica) was changed to 40/60, 60/40, and 70/30, respectively. did.
[0152]

The above additives were mixed and dispersed using a horizontal bead mill (System Zetamini manufactured by Ashizawa) filled with zirconia beads of 0.3 mm at a volume ratio of 60% to obtain a yellow pigment dispersion 1. The average particle size of the obtained yellow pigment was 112 nm.
[0153]

Each of the above additives was mixed and dispersed using a horizontal bead mill (a system zeta mini manufactured by Ashizawa) filled with 0.3% zirconia beads at a volume ratio of 60% to obtain a magenta pigment dispersion 1. The average particle size of the obtained magenta pigment was 105 nm.
[0154]

The above additives were mixed and dispersed using a horizontal bead mill (System Zeta Mini manufactured by Ashizawa) filled with zirconia beads of 0.3 mm at a volume ratio of 60% to obtain a cyan pigment dispersion 1. The average particle size of the obtained cyan pigment was 87 nm.
[0155]

The above additives were mixed and dispersed using a horizontal bead mill (System Zeta Mini manufactured by Ashizawa) filled with zirconia beads of 0.3 mm at a volume ratio of 60% to obtain a black pigment dispersion 1. The average particle size of the obtained black pigment was 75 nm.
[0156]
(Preparation of pigment ink set 1)
<Preparation of Yellow Dark Ink 1>
Yellow pigment dispersion 1 15% by mass
Ethylene glycol 20% by mass
Diethylene glycol 10% by mass
Surfactant (Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd.) 0.1% by mass
54.9% by mass of ion-exchanged water
Each of the above compositions was mixed, stirred, and filtered through a 1 μm filter to prepare a yellow deep ink 1, which is an aqueous pigment ink of the present invention. The average particle size of the pigment in the ink was 120 nm, and the surface tension γ was 36 mN / m.
[0157]
<Preparation of Yellow Light Ink 1>
Yellow pigment dispersion 1 3% by mass
Ethylene glycol 25% by mass
Diethylene glycol 10% by mass
Surfactant (Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd.) 0.1% by mass
61.9% by mass of ion-exchanged water
Each of the above compositions was mixed, stirred, and filtered with a 1 μm filter to prepare Yellow Light Ink 1, which is an aqueous pigment ink of the present invention. The average particle size of the pigment in the ink was 118 nm, and the surface tension γ was 37 mN / m.
[0158]
<Preparation of magenta dark ink 1>
Magenta pigment dispersion 1 15% by mass
Ethylene glycol 20% by mass
Diethylene glycol 10% by mass
Surfactant (Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd.) 0.1% by mass
54.9% by mass of ion-exchanged water
Each of the above compositions was mixed, stirred, and filtered with a 1 μm filter to prepare a magenta dark ink 1, which is an aqueous pigment ink of the present invention. The average particle size of the pigment in the ink was 113 nm, and the surface tension γ was 35 mN / m.
[0159]
<Preparation of magenta light ink 1>
Magenta pigment dispersion 1 3% by mass
Ethylene glycol 25% by mass
Diethylene glycol 10% by mass
Surfactant (Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd.) 0.1% by mass
61.9% by mass of ion-exchanged water
Each of the above compositions was mixed, stirred, and filtered through a 1 μm filter to prepare magenta pale ink 1, which is an aqueous pigment ink of the present invention. The average particle size of the pigment in the ink was 110 nm, and the surface tension γ was 37 mN / m.
[0160]
<Preparation of Cyan Dark Ink 1>
Cyan pigment dispersion 1 10% by mass
Ethylene glycol 20% by mass
Diethylene glycol 10% by mass
Surfactant (Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd.) 0.1% by mass
59.9% by mass of ion-exchanged water
Each of the above compositions was mixed, stirred, and filtered with a 1 μm filter to prepare a cyan pigmented ink 1 as an aqueous pigment ink of the present invention. The average particle size of the pigment in the ink was 95 nm, and the surface tension γ was 36 mN / m.
[0161]
<Preparation of cyan light ink 1>
Cyan pigment dispersion 1 2% by mass
Ethylene glycol 25% by mass
Diethylene glycol 10% by mass
Surfactant (Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd.) 0.2% by mass
62.8% by mass of ion-exchanged water
Each of the above compositions was mixed, stirred, and filtered with a 1 μm filter to prepare a cyan light ink 1 which is an aqueous pigment ink of the present invention. The average particle size of the pigment in the ink was 92 nm, and the surface tension γ was 33 mN / m.
[0162]
<Preparation of black dark ink 1>
Black pigment dispersion 1 10% by mass
Ethylene glycol 20% by mass
Diethylene glycol 10% by mass
Surfactant (Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd.) 0.1% by mass
59.9% by mass of ion-exchanged water
Each of the above compositions was mixed, stirred, and filtered with a 1 μm filter to prepare Black Ink 1, which is an aqueous pigment ink of the present invention. The average particle size of the pigment in the ink was 85 nm, and the surface tension γ was 35 mN / m.
[0163]
<Preparation of Black Light Ink 1>
Black pigment dispersion 1 2% by mass
Ethylene glycol 25% by mass
Diethylene glycol 10% by mass
Surfactant (Surfinol 465 manufactured by Nissin Chemical Industry Co., Ltd.) 0.1% by mass
62.9% by mass of ion-exchanged water
Each of the above compositions was mixed, stirred, and filtered with a 1 μm filter to prepare a black light ink 1 which is an aqueous pigment ink of the present invention. The average particle size of the pigment in the ink was 89 nm, and the surface tension γ was 36 mN / m.
[0164]
[Preparation of pigment ink set 2]
The same procedure was repeated except that an acrylic emulsion (iodazole GD86B Tg 60 ° C., average particle size 90 nm, manufactured by NCS Japan) was added to each of the eight inks prepared in the pigment ink set 1 in an amount equivalent to 8% by mass. Was prepared.
[0165]
[Preparation of colorant-free liquid (CI ink)]
(Preparation of CI ink 1)
Polyvinyl alcohol PVA117 (manufactured by Kuraray) Solid content 1.0% by mass
Ethylene glycol 22.0% by mass
Glycerin 8.0% by mass
Triethylene glycol monobutyl ether 5.0% by mass
2.0 mass% of 2-pyrrolidone
Surfynol 465 (manufactured by Nissin Chemical Industry Co., Ltd.) 0.5% by mass
Added pure water to finish to 100% by mass
(Preparation of CI ink 2)

(Preparation of CI ink 3)
CI ink 3 was prepared in the same manner as in the preparation of CI ink 2 except that resin 1 was changed to resin 2 (acrylate copolymer: Tg 75 ° C, average particle size 0.5 μm).
[0166]
(Preparation of CI ink 4)
CI ink 4 was prepared in the same manner as in the preparation of CI ink 2 except that resin 1 was changed to resin 3 (acrylate copolymer: Tg 75 ° C, average particle diameter 1.2 µm).
[0167]
(Preparation of CI ink 5)
CI ink 5 was prepared in the same manner as in the preparation of CI ink 2 except that resin 1 was changed to resin 4 (acrylate copolymer: Tg 56 ° C, average particle size 0.3 μm).
[0168]
<< Inkjet image formation >>
The above-prepared pigment ink set (8 shades) and CI ink were added to an ink jet printer having a heating / pressing roller pair for simultaneously performing the pressing process and the heating process shown in FIG. 1 and equipped with 9 recording heads. And the recording media 1 to 5, Konica Corporation's PhotoJet Paper QP (abbreviated as QP in the table), Seiko Epson Corporation PM photo paper (abbreviated as PM in the table) And the combination shown in Table 1 and an output condition of 1.5 m ² / Hour, and output a solid image of yellow, magenta, cyan, and black, and a grid-like test chart in which Y, M, C, B, G, R, and Bk bands each having a width of 1 cm vertically and horizontally are drawn. .
[0169]
The emission area of the CI ink at the time of image formation was determined according to the following method.
The reflection densities of wedge images of Y, M, C, B, G, R, and Bk, which were prepared by printing only the eight color pigment inks under the above conditions, were measured using an X-write 938 (manufactured by X-rite). Then, any of the Y, M, and C densities is measured and set in advance for an ink ejection amount in an area where the density exceeds 1.0, and in the above-described printing, only in an image area exceeding the set ink ejection amount, It was programmed to emit a predetermined amount of CI ink. However, when forming the image 7, the CI ink was not used.
[0170]
After that, the image 1 was processed by placing it in an oven at 100 ° C. for 5 minutes without using the heat and pressure fixing device in the apparatus, and the images 2 to 15 were processed by the heat and pressure fixing device in the apparatus. Was heated and pressed at a surface temperature of 100 ° C. and a pressure of 5 MPa.
[0171]
<< Characteristic evaluation of formed image >>
Each characteristic evaluation was performed on the formed image created by the above method according to the following method.
[0172]
(Measurement of image density)
With respect to the black solid image portion prepared above, a visual density 1 was measured by a reflection densitometer (X-rite 938).
[0173]
(Fingerprint adhesion resistance)
After applying fingerprints to the black solid image area created above by ten subjects, the fingerprints were lightly wiped off with a tissue paper, and the visual density 2 of the portion with the fingerprint was measured, and the density change rate was measured according to the following equation. Then, an average value of 10 subjects was obtained.
[0174]
ΔD = density after fingerprint processing (visual density 2) −unprocessed density (visual density 1)
The smaller ΔD is, the smaller the change in density after the fingerprint is attached is.
[0175]
(Evaluation of glossiness)
The glossiness of each solid image created above was classified and evaluated by 20 observers according to the following criteria, and the one with the highest classification was adopted.
[0176]
5: Good glossiness in all colors
4: Slightly lack glossiness in high image density portions of green and red.
[0177]
3: Lack of glossiness in high image density portions of yellow, black, green, and red
2: Lack of glossiness in high image density portions of yellow, magenta, cyan, and black
1: Low glossiness at all colors and all densities
(Measurement of C value)
The C value of the black solid image portion prepared above was measured at a reflection angle of 60 ° using an image clarity measuring device (ICM-1DP) manufactured by Suga Test Instruments Co., Ltd.
[0178]
(Evaluation of gloss difference)
The black solid image portion and the unprinted portion (white background) prepared above were visually compared to determine whether there was a gloss difference.
[0179]
(Evaluation of bronzing resistance)
For each output image, bronzing, which is a phenomenon peculiar to the pigment and causes a reduction in image quality, was evaluated by the following method. Evaluation of bronzing was performed by observing the image from various angles under a fluorescent lamp (80 °, 60 °, 45 °, 30 ° when 90 ° right above and 0 ° right beside) based on the following criteria. Evaluation was performed in accordance with the following.
[0180]
3: No bronzing (metallic luster) is observed at any angle
2: Observation from some angles shows weak bronzing in some ink images
1: Bronzing is observed at almost all angles
(Evaluation of scratch resistance)
A solid black image portion of each of the images formed above was measured using a scratch strength tester HEIDON-18 (manufactured by HEIDON) under an atmosphere of 25 ° C. and 50% RH, and a 0.1 mmR sapphire needle was used as a measuring needle. Then, the scratch strength was measured. For the measurement, a scratch test was performed three times with a load of 0 to 10 g being changed in a range of 10 cm, the minimum load at which an image was damaged was defined as scratch strength, and the measured value was used as a measure of scratch resistance.
[0181]
(Evaluation of film peeling resistance)
In the above-described inkjet image formation, the image output condition was 3.0 m. ² In the same manner as above, except that the time was changed to / time, for each of these images, an area equivalent to 40 m of roll paper was visually observed, the presence or absence of film peeling was evaluated, and the film peeling resistance was evaluated according to the following criteria. Was done.
[0182]
4: Image output speed is 3m ² Film peeling does not occur even under the conditions of
3: Image output speed is 2m ² 3 / m ² / Cm condition ² Less than 1 to 5 film scatters
2: Image output speed is 2m ² / Cm under the condition of / hour ² The film peeling less than 1 to 3 is scattered.
[0183]
1: Image output speed is 2m ² / Cm under the condition of / hour ² Less than 4 to 10 membranes were observed, and 1 cm ² The above films are also scattered
Table 1 shows the results obtained as described above.
[0184]
[Table 1]

[0185]
As is clear from Table 1, the present invention formed by applying a liquid containing a resin and containing substantially no colorant to an image area having a density of 1.0 or more, and then performing a heat and pressure treatment. The image of Comparative Example, especially in the black ink image, the image density and C value were high, the fingerprint adhesion resistance, glossiness, gloss difference, bronzing resistance and scratch resistance were excellent, and when high-speed printing was performed. It can be seen that the film has good film peeling resistance.
[0186]
Further, as a result of comparing the solid black portion of the image created above with black of Japan Color, the image of the present invention had a color tone close to that of Japan Color, and black without reddish or bluish was reproduced. However, the black of the image 1 as a comparative example was slightly reddish.
[0187]
Regarding the ejection stability of the CI ink, printing was performed by the above-described image forming method, and after leaving for 10 days, printing was performed again. As a result, ejection failure was observed with the CI ink 1, but with respect to the CI inks 2 to 5, No emission failure was observed at all.
[0188]
Further, in addition to the items evaluated above, for each of the images created above, as a result of observing occurrence of beading in solid images of each color and color bleed at the boundary of the grid-like test chart, the image output speed was 2 m. ² Under the condition of / time, no beading or color bleed was observed in all images of the present invention, and high-quality images were obtained. Also, the image output speed is 3m ² Under the condition of / time, in the image using the recording medium 1, a large amount of beading and color bleeding occurred, and the image could not be used as photographic image quality. Further, in the recording medium 1, image defects such as peeling of the film occurred in a part of the image, and dirt was confirmed on the roller surface of the heating and pressing device. On the other hand, images using recording media 2 to 5 in which silica was mixed in the surface layer did not generate beading and color bleed, or did not generate much, confirming very good results. Was completed.
[0189]
【The invention's effect】
According to the present invention, a high maximum density can be obtained, pure black without reddish or bluish can be reproduced, fingerprint adhesion resistance, glossiness, gloss difference, bronzing resistance, scratch resistance are excellent, and image quality is less deteriorated even at high speed printing. An inkjet image forming method can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of an ink jet recording apparatus used in the present invention.
FIG. 2 is a schematic configuration diagram showing another example of the ink jet recording apparatus used in the present invention.
[Explanation of symbols]
1, 1a recording medium
2 Recording medium transport means
21 Transport Roller Pair
3 Recording head
34 Recording medium holder
4 heating and pressurizing means
41 Heating roller
42 pressure roller
43 Heating element
44 Heating belt
45 Lower pressure belt
46 driven roller
5 Temperature sensor
6 Recording medium cutting means
61, 62 cutter
7 sag forming means
71 First Roller Pair
72 Second roller pair

Claims (5)

In a method of printing an image on an inkjet recording medium using a pigment ink, and an inkjet image forming method of forming an image through a step of heating and pressing the formed image, an image region having a density of 1.0 or more is formed. An ink jet image forming method comprising applying a liquid containing a resin and containing substantially no colorant to at least a part thereof. 2. The method according to claim 1, wherein the resin is an aqueous resin emulsion. The inkjet image forming method according to claim 1, wherein at least one of the pigment inks has a resin content solid content in the pigment ink less than the pigment solid content. The ink-jet recording medium has two or more ink-absorbing layers on a support, and a surface layer, which is an ink-absorbing layer farthest from the support, contains a thermoplastic resin. Item 4. The inkjet image forming method according to any one of Items 1 to 3. The method according to claim 4, wherein the surface layer further includes inorganic fine particles.

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