JP2004188704A - Ink jet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet recording method which is superior in terms of gloss, flatness (blister resistance) and touch with a low incidence of coating film release and image defects. <P>SOLUTION: This ink jet recording method records an image by supplying an ink to an ink jet recording medium which has at least one ink absorbing layer as a surface layer located farthest from the support and thermally treats the medium under pressure. In addition, the method includes a drying step to dry the equivalent to 10 to 50 mass% of the maximum ink loadings prior to thermal pressurizing treatment. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０１３０】
（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。
【０１３１】
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）
上記下層用塗布液１を調製した後、４３℃で３０分撹拌した後、熱可塑性微粒子（アクリル系ラテックス、Ｔｇ８２℃、個数平均粒子径１６０ｎｍ、固形分４０％）を、熱可塑性微粒子（Ｂ）／フィラー（Ｆ：シリカ）の固形分比（Ｂ／Ｆ）が５０／５０になるように１５分かけて添加して、表層用塗布液１を調製し、１０μｍのフィルターで濾過を行った後、４３℃で１０時間停滞して、塗布に使用した。
【０１３２】
（記録媒体１の作製）
両面を低密度ポリエチレン（ＬＤＰＥ）で被覆した紙支持体１（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、塗布は、下層はシリカの付き量が１８ｇ／ｍ^２となるように、また表層はシリカの付き量が３ｇ／ｍ^２となるように行った。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。
【０１３３】
《インクの作製》
〔顔料インクの調製〕
（顔料分散液の調製）
〈イエロー顔料分散体１の調製〉

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。
【０１３４】
〈マゼンタ顔料分散体１の調製〉

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。
【０１３５】
〈シアン顔料分散体１の調製〉

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。
【０１３６】
〈ブラック顔料分散体１の調製〉

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。
【０１３７】
（顔料インクの調製）
〈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） 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。
【０１３８】
〈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） 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。
【０１３９】
〈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） 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。
【０１４０】
〈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） 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。
【０１４１】
〈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） 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。
【０１４２】
〈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） 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。
【０１４３】
〈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） 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。
【０１４４】
〈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） 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。
【０１４５】
《インクジェット画像形成》
（画像の印字）
印字環境として、２３℃、５５％ＲＨの常温常湿と、３２℃、８０％ＲＨの高温高湿の２条件で、下記の方法に従って画像印字を行った。
【０１４６】
図１に記載の加熱加圧処理を同時に行う加熱加圧ローラ対を有する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をセットし、前記作製した記録媒体をロール状元巻より供給し、全顔料インク（８種）の最大打ち込みインク量が１０ｍｌ／ｍ^２と２０ｍｌ／ｍ^２となる２条件でベタ画像を印字した。なお、このときの各色インクの吐出量は、全て均等に、同一インク液滴量が出射するように出射条件を調整した。
【０１４７】
（形成画像の乾燥）
上記条件で記録媒体上に、顔料インクを出射した後、乾燥部で表１に記載の乾燥減量となるように、印字面から５ｃｍの距離から５００Ｗの市販のドライヤーを用いて、所定量のインク溶媒の乾燥を行った。
【０１４８】
（加熱加圧処理）
次いで、加熱加圧定着器にて、定着器の表面温度を１０５℃、ニップ圧を１ＭＰａ、線速７ｍｍ／ｓで加熱加圧処理を行って、各画像を作成した。
【０１４９】
なお、加熱加圧ローラ対のうち、記録媒体の表層に接す面側に配置した加熱加圧ローラは表面粗さが１００ｎｍで、ハロゲンヒーターを内蔵し、被覆層を有する金属ローラを用いた。
【０１５０】
《形成画像の特性評価》
上記方法により作成した各ベタ画像について、下記の方法に従ってＣ値の測定を行い、得られた結果を表１に示す。
【０１５１】
上記作成したベタ画像を、写像性測定器ＩＣＭ−１ＤＰ（スガ試験機械社製）で反射６０度、光学くし２ｍｍでの鏡面光沢度（Ｃ値％）を測定した。
【０１５２】
【表１】

【０１５３】
表１より明らかなように、表層に熱可塑性樹脂を含む記録媒体上に画像形成した後、加熱加圧処理前に、最大打ち込みインク量の１０〜５０質量％相当量の溶媒の蒸発、乾燥を施した本発明は、比較例に対し、常温常湿環境で形成した画像と、高温高湿環境で形成した画像ともに、良好な光沢性を有するインクジェット画像を得ることができた。
【０１５４】
実施例２
《記録媒体の作製》
〔記録媒体２〜５の作製〕
実施例１に記載の記録媒体１の作製で用いた紙支持体１（両面を低密度ポリエチレン（ＬＤＰＥ）で被覆した紙支持体）において、ラミネート素材を低密度ポリエチレン（ＬＤＰＥ）に代えて、表２に記載のラミネート素材を用いた以外は同様にして、記録媒体２〜５を作製した。なお、各ラミネート素材の被覆量は、紙支持体１と同一量にした。
【０１５５】
なお、表２に記載の各ラミネート素材の詳細は、以下の通りである。
ＬＤＰＥ：低密度ポリエチレン
ＨＤＰＥ：高密度ポリエチレン
ＰＰ：ポリプロピレン
ＰＥＴ：ポリエチレンテレフタレート
《インクジェット画像形成》
（画像の印字）
印字環境として、２３℃、５５％ＲＨの常温常湿の環境下で、下記の方法に従って画像印字を行った。
【０１５６】
実施例１と同様に、図１に記載の加熱加圧処理を同時に行う加熱加圧ローラ対を有するインクジェットプリンターに、実施例１に記載の顔料インクセットをセットし、前記作製した各記録媒体をロール状元巻より供給し、全顔料インク（８種）の最大打ち込みインク量が２０ｍｌ／ｍ^２となる条件でベタ画像を印字した。なお、このときの各色インクの吐出量は、全て均等に、同一インク液滴量が出射するように出射条件を調整した。
【０１５７】
（形成画像の乾燥）
上記条件で記録媒体上に、顔料インクを出射した後、乾燥部で乾燥率が１２質量％となるように、印字面から５ｃｍの距離から５００Ｗの市販のドライヤーを用いて、インク溶媒の乾燥を行った条件と、全く乾燥を行わない条件で処理を行った。
【０１５８】
（加熱加圧処理）
次いで、加熱加圧定着器にて、定着器の表面温度を各記録媒体で用いたラミネート素材の溶融温度より５℃低い条件とし、ニップ圧を１ＭＰａ、線速７ｍｍ／ｓで加熱加圧処理を行って、各画像を作成した。
【０１５９】
なお、加熱加圧ローラ対のうち、記録媒体の表層に接す面側に配置した加熱加圧ローラは表面粗さが１００ｎｍで、ハロゲンヒーターを内蔵し、被覆層を有する金属ローラを用いた。
【０１６０】
《形成画像の特性評価》
上記方法により作成した各ベタ画像について、実施例１に記載の方法に従ってＣ値の測定と、下記の方法に従って、ブリスターの発生の有無及び触感（風合い）の評価を行い、得られた結果を表２に示す。
【０１６１】
（ブリスターの評価）
加熱定着処理後の記録媒体について、加熱加圧処理後に凹凸の発生の有無を目視観察した。
【０１６２】
（触感：風合いの評価）
加熱定着処理後の記録媒体を、巾１０．２ｃｍ、長さ１５．２ｃｍに断裁し、記録媒体の端部を指で挟んで持ち、腰の強さ、しなやかさの記録媒体としての風合いを下記に記載の基準に則り、感覚評価を行った。
【０１６３】
◎：銀塩写真（カラーペーパー）と全く同等のしなやかさ、腰の強さがある
○：銀塩写真（カラーペーパー）と同等のしなやかさ、腰の強さがある
△：銀塩写真（カラーペーパー）に比較し、ややしなやかさに欠け、剛性感を受ける
×：銀塩写真（カラーペーパー）に比較し、腰が強すぎて、しなやかさに欠け、強い違和感を感じる
【０１６４】
【表２】

【０１６５】
表２から明らかなように、印字後、最大打ち込みインク量の１２質量％相当量の乾燥処理を施し、かつ紙支持体で用いたラミネート素材の溶融点以下の温度で加熱加圧定着を施すことにより、ブリスターの発生がなく、かつ高い光沢を有する画像を得ることができた。また、紙支持体のラミネート素材として、低密度ポリエチレン（ＬＤＰＥ）を用いることにより、銀塩写真（カラーペーパー）に近似のしなやかさ、腰の強さがあるインクジェットプリントを得ることができた。
【０１６６】
実施例３
《記録媒体の作製》
〔記録媒体６〜１１の作製〕
実施例１に記載の記録媒体１の作製において、表層の熱可塑性微粒子／フィラー（シリカ）の固形分比を、表３に記載のように変更した以外は同様にして、記録媒体６〜１１を作製した。
【０１６７】
《インクジェット画像形成》
（画像の印字）
印字環境として、２３℃、５５％ＲＨの常温常湿の環境下で、下記の方法に従って画像印字を行った。
【０１６８】
実施例１と同様に、図１に記載の加熱加圧処理を同時に行う加熱加圧ローラ対を有するインクジェットプリンターに、実施例１に記載の顔料インクセットをセットし、上記作製した各記録媒体をロール状元巻より供給し、全顔料インク（８種）の最大打ち込みインク量が２０ｍｌ／ｍ^２となる条件でベタ画像を印字した。なお、このときの各色インクの吐出量は、全て均等に、同一インク液滴量が出射するように出射条件を調整した。
【０１６９】
（形成画像の乾燥）
上記条件で記録媒体上に、顔料インクを出射した後、乾燥条件を行わなかった水準と、乾燥部で表３に記載の乾燥率（％）となるように、印字面から５ｃｍの距離から５００Ｗの市販のドライヤーを用いて、インク溶媒の乾燥を行った水準とで処理した。
【０１７０】
（加熱加圧処理）
次いで、加熱加圧定着器にて、定着器の表面温度を１０５℃、ニップ圧を１ＭＰａ、線速７ｍｍ／ｓで加熱加圧処理を行って、各画像を作成した。
【０１７１】
なお、加熱加圧ローラ対のうち、記録媒体の表層に接す面側に配置した加熱加圧ローラは表面粗さが１００ｎｍで、ハロゲンヒーターを内蔵し、被覆層を有する金属ローラを用いた。
【０１７２】
《形成画像の特性評価》
上記方法により作成した各ベタ画像について、実施例１に記載の方法に従ってＣ値の測定と、下記の方法に従って、画像形成後の塗膜品質の評価を行い、得られた結果を表３に示す。
【０１７３】
（塗膜品質の評価）
上記作成した記録媒体表面を、目視及びルーペを用いて塗膜の状態を観察し、下記の基準に則り塗膜品質の評価を行った。
【０１７４】
○：形成した記録媒体に、画像以上は全く認められない
△：ごく一部に、支持体からの膜剥がれや表層の膨らみが認められるが、実用上許容の範囲にある
×：明らかに、支持体からの膜剥がれや表層の膨らみが認められ、実用上問題となる品質である
【０１７５】
【表３】

【０１７６】
表３より明らかなように、実施例１、２の結果と同様に、印字後、最大打ち込みインク量の１０〜５０質量％相当量の乾燥処理を施した本発明の水準は、比較例に対し、光沢性に優れていることが分かる。更に、表層での熱可塑性樹脂と無機微粒子の比率を４０／６０〜７０／３０の範囲とすることにより、乾燥部での水分等の蒸発に加え、加熱加圧処理した後でも表層部に空隙が存在することにより、更にインク溶媒の拡散及び蒸発が生じることにより、膜剥がれや膜の膨らみのない安定した塗膜を形成することができた。
【０１７７】
【発明の効果】
本発明により、光沢性、平面性（ブリスター耐性）、風合い（触感）に優れ、かつ塗膜剥がれ及び画像欠陥が低減されたインクジェット記録方法を提供することができた。
【図面の簡単な説明】
【図１】本発明で用いることのできる乾燥部及び加熱加圧ローラを有するインクジェット記録装置の一例を示す概略構成図である。
【図２】本発明で用いることのできる乾燥部及び加熱加圧ベルトを有するインクジェット記録装置の一例を示す概略構成図である。
【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
４２ 加圧ローラ
４３ 発熱体
４４ 定着ベルト
４５ 下部圧着ベルト
４６ 従動ローラ
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のローラ対
７２ 第２のローラ対
８ 乾燥ゾーン
９ 乾燥部
１０ 乾燥風[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a novel ink jet recording method, and more particularly, to an ink jet recording method which is excellent in glossiness, flatness, texture (touch), and has reduced coating film peeling and image defects.
[0002]
[Prior art]
2. Description of the Related Art In recent years, the progress of inkjet technology has been remarkable, and coupled with improvements in printer technology, ink technology, and dedicated inkjet recording medium technology, high image quality, such as photographic image quality, has been achieved. With this improvement in image quality, the storability of ink-jet images has been compared with conventional silver halide photographs, and in many dye inks, the transfer of colorants such as water resistance and poor bleeding resistance of ink-jet images has been reduced. It has been pointed out that deterioration accompanied by a chemical reaction peculiar to a coloring agent such as weakness against light resistance and resistance to oxidizing gas is caused.
[0003]
On the other hand, many methods using a pigment ink have been proposed in order to improve the storability of a dye ink image. However, when a pigment ink is used, glossiness such as a silver halide photograph cannot be obtained, or metallic luster called bronzing may be observed, which has many problems. Further, at present, sufficient image storability comparable to a photographic image has not been obtained simply by using pigment ink.
[0004]
Among the above-mentioned problems, many proposals have been made so far for the purpose of improving the image storability of an ink jet recorded image. As the inkjet recording medium, a layer made of thermoplastic organic polymer particles is provided on the outermost layer of the inkjet recording medium, and after the image is recorded, the thermoplastic organic polymer particles are subjected to a heat fixing treatment, thereby melting and forming a film. As a result, there has been proposed a method of forming an image having high gloss and comparable to a photographic image by forming a polymer protective film (for example, see Patent Documents 1 to 5).
[0005]
However, in such an inkjet recording medium containing thermoplastic organic polymer particles in the outermost layer, an image having high gloss can be obtained when an image is formed under a normal environment. However, when a print is output under a severe environment, for example, under a condition of high temperature and high humidity, there is a problem that gloss is reduced. This is because the ink droplets ejected on the inkjet recording medium do not sufficiently dry in a high-temperature and high-humidity environment. It becomes necessary. At this time, if the heating and pressurizing treatment is performed under the same heat energy condition as that under the normal temperature and normal humidity environment, sufficient smoothness and gloss of the image recording surface may be reduced due to the influence of moisture and the like still contained in the ink. This causes peeling and failure of the melted and formed thermoplastic resin film.
[0006]
In order to solve the above-mentioned problem, a method of forming a laminate layer on the image recording surface side by heating and pressurizing treatment without forming a gap, by removing moisture contained in the laminate layer, swelling at the time of forming the laminate layer, offset, layer A method for preventing peeling or the like has been proposed (for example, see Patent Document 6).
[0007]
Also, when evaporating and drying the water and the like of the ejected ink, the melting point of the support material used is low, and if drying is performed at a temperature equal to or higher than the melting point to promote drying, a support called a blister is formed. As a result, deformation is caused, and at present, a method has not been found that can impart both glossiness and smoothness and stability of a thermoplastic resin film.
[0008]
[Patent Document 1]
JP-A-59-222381
[0009]
[Patent Document 2]
JP-A-4-21446
[0010]
[Patent Document 3]
JP-A-10-315448
[0011]
[Patent Document 4]
JP-A-11-5362
[0012]
[Patent Document 5]
JP-A-11-192775
[0013]
[Patent Document 6]
Patent No. 2908518
[0014]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet recording method which is excellent in glossiness, flatness, texture (touch), and has reduced coating film peeling and image defects. .
[0015]
[Means for Solving the Problems]
The above object of the present invention is achieved by the following configurations.
[0016]
1. An image is formed by applying ink to an inkjet recording medium having at least one ink absorbing layer on a support, and a surface layer, which is an ink absorbing layer located farthest from the support, containing a thermoplastic resin. An ink jet recording method in which recording is performed, and thereafter, heating and pressurizing treatment is performed. Before performing the heating and pressurizing treatment, the ink is dried by an amount equivalent to 10% by mass or more and 50% by mass or less of the maximum amount of ink discharged. An ink jet recording method comprising a drying step performed.
[0017]
2. 2. The inkjet recording method according to claim 1, wherein the content ratio of the thermoplastic resin in the surface layer is 40% by mass or more and 70% by mass or less.
[0018]
3. 3. The ink jet recording method according to claim 1, wherein the support is a resin-coated paper in which both sides of the paper are coated with a resin.
[0019]
4. 4. The ink jet recording method according to claim 3, wherein at least one of the resins covering both sides of the paper is a low-density polyethylene.
[0020]
5. 5. The ink jet recording method according to claim 3, wherein a heating temperature at the time of the heating and pressurizing treatment is equal to or lower than a melting point of a resin coating both sides of the paper.
[0021]
6. The ink absorption capacity of the surface layer is 20 ml / m ² 6. The ink jet recording method according to any one of the above items 1 to 5, wherein:
[0022]
7. 7. The ink jet recording method according to any one of items 1 to 6, wherein the ink is a pigment ink containing a pigment.
[0023]
The present inventors have made intensive studies in view of the above problems, and as a result, have found that as an ink jet recording method, at least one ink absorbing layer is provided on a support, and an ink absorbing layer located at a position farthest from the support is provided. An ink-jet recording method in which an ink is applied to an ink-jet recording medium whose surface layer contains a thermoplastic resin (hereinafter, also simply referred to as a recording medium) to record an image, and then heat and pressure is applied. Before performing the pressure treatment, the ink is subjected to a drying step of drying the ink in an amount equivalent to 10% by mass or more and 50% by mass or less of the maximum amount of the ejected ink, so that the gloss, the flatness, and the texture (tactile sensation) are improved. The inventors have found that an ink jet recording method which is excellent and in which coating film peeling and image defects are reduced can be realized, and the present invention has been reached.
[0024]
Further, the content ratio of the thermoplastic resin in the surface layer is 40% by mass or more and 70% by mass or less, a resin-coated paper in which both sides of the paper are coated with a resin is used as a support, and the resin which covers both sides of the paper is used. At least one type is a low-density polyethylene, the heating temperature during the heating and pressurizing treatment is set to be equal to or lower than the melting point of the resin coating both sides of the paper, and the ink absorption capacity of the surface layer is 20 ml / m2. ² As described above, it has been found that the effect can be further exhibited by using a pigment ink containing a pigment.
[0025]
In the configuration of the present invention, an ink, preferably a pigment ink, is ejected onto an inkjet recording medium containing a thermoplastic resin in the surface layer to form an image, and then the thermoplastic resin in the surface layer is melted and heated to form a film. Before the treatment, the solvent (e.g., moisture, organic solvent, etc.) of the printed ink is evaporated and dried to a specific range through a drying step. In the present invention, the solvent is completely removed. It is not necessary, and the solvent may remain to some extent during the heating and pressurizing treatment. Further, in the above method, by using a resin-coated paper in which both sides of the paper are coated with a resin as the support, it is possible to obtain a high-gloss ink-jet print that is stiff and has a tactile sensation and texture close to a photographic image print.
[0026]
Hereinafter, details of the present invention will be described.
First, an inkjet recording apparatus used in the inkjet recording method of the present invention will be described.
[0027]
In the ink jet recording method of the present invention, there is no particular limitation as long as it has a recording medium storage section, a transport section, an ink cartridge, and an ink jet print head as in a commercially available printer, but at least a roll-shaped recording medium storage A series of printer sets including a unit, a transport unit, an ink jet print head, a cutting unit, a drying unit, a heating and pressurizing unit, and a recording print storage unit are useful for commercial use of ink jet photography.
[0028]
The recording head may be of a piezo type, a thermal type, or a continuous type, but the piezo type is particularly preferable from the viewpoint of stability with pigment ink.
[0029]
One example of an ink jet recording apparatus that can be used in the present invention is shown in FIGS.
[0030]
FIG. 1 is a schematic configuration diagram illustrating an example of an inkjet recording apparatus having a drying unit and a heating and pressing roller.
[0031]
In FIG. 1, the recording medium 1 sent out from the original winding roll A of the recording medium by the transport roller pair 21 is ejected with the recording head 3 to perform ink jet recording, and is appropriately cut by the cutters 61 and 62. The sheet is conveyed to the first roller pair 71 and the second roller pair 72 in a state having a bend.
[0032]
Next, the ink (e.g., water or organic solvent) in the printed ink is conveyed to a drying zone 8 where the solvent evaporates to a specified condition, and a corresponding amount of 10% by mass or more and 50% by mass or less of the maximum amount of ink discharged is dried. Thereafter, the toner is sent to the heating / pressing unit 4 and passes between a heating roller 41 having a heating element 43 therein and a pressure roller 42 to perform a heat fixing process.
[0033]
FIG. 2 is a schematic configuration diagram illustrating an example of an inkjet recording apparatus having a drying unit and a heating and pressing belt.
[0034]
The recording medium printed and dried in the same manner as in FIG. 1 is sent to the heating / pressing means 4 and passes along with the fixing belt 44 between the heating roller 41 having the heating element 43 therein and the pressure roller 42. Then, a heat fixing process is performed.
[0035]
The drying unit according to the present invention is not particularly limited as long as it is a method capable of evaporating the solvent in the ink in a specified amount.For example, a method of blowing dry hot air with controlled temperature and humidity, a heat roller or a heat roller A method of arranging a plate or the like to heat and dry the recording medium, or a method of having a closed structure and evaporating under reduced pressure can be mentioned, but from the viewpoint of easy operation and easy control of drying conditions, A method of blowing dry air is preferred.
[0036]
The present invention is characterized in that the ink printed on the recording medium is dried by evaporating a solvent corresponding to 10 to 50% by mass of the maximum amount of ink discharged as the ink. The maximum ejection ink amount referred to in the present invention is an ink amount (g / m) in an area where the largest amount of ink is ejected in one image forming process. ² ), And there is a case where the ink is a single color ink or a case where a plurality of multicolor inks are stacked. In the present invention, the maximum ejection ink amount is preferably 10 to 50 ml / m ² It is.
[0037]
As the heating / pressing fixing method that can be used in the present invention, in addition to the above description, a heating / pressing device including a heating / pressing belt on the surface side in contact with the image recording surface and a holding roller having a member in contact with the back side is used. You can also.
[0038]
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.
[0039]
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.
[0040]
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.
[0041]
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.
[0042]
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.
[0043]
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.
[0044]
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.
[0045]
In the present invention, the heating and pressurizing conditions are preferably a pressure of 0.5 to 10 MPa and a heat and pressure treatment at a temperature of 50 to 150 ° C., more preferably a pressure of 0.5 to 5 MPa, It is a temperature condition of 70 to 130 ° C. At this time, the heating temperature should be lower than the melting point of the resin coating both sides of the paper of the support constituting the recording medium, so that the smoothness is high and the occurrence of blisters (thermal deformation of the support) is suppressed. Is preferred because
[0046]
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.
[0047]
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.
[0048]
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.
[0049]
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 at least one ink-absorbing layer on a support, and a surface layer which is an ink-absorbing layer located farthest from the support contains a thermoplastic resin. One
Generally, the ink absorbing layer is broadly classified into a swelling type and a void type.
[0050]
As the swelling type, a water-soluble binder is used, for example, gelatin, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide or the like is applied alone or in combination, and this is used as an ink absorbing layer.
[0051]
The void type is obtained by mixing and applying fine particles and a water-soluble binder, and is particularly preferably a glossy type. As the fine particles, alumina or silica is preferable, and those using silica having a particle diameter of 0.1 μm or less are particularly preferable. As the water-soluble binder, those using gelatin, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene oxide or the like alone or in combination are preferable.
[0052]
Of the above two types, to accommodate continuous high-speed printing, it is more suitable for the recording medium to have a high ink absorption rate, and from this point, the void type can be particularly preferably used in the present invention.
[0053]
Hereinafter, the void-type ink absorbing 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 have been 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 resin on a support, drying the ink, and immersing the ink jet recording paper in a liquid containing water or a suitable organic solvent. A method of forming voids by dissolving solid fine particles, a method of forming a void in a film by applying a coating solution containing a compound having a property of foaming during film formation, and then foaming this compound in a drying process, A method of applying a coating solution containing porous solid fine particles and a hydrophilic binder on a support, and forming voids in the porous fine particles or between the fine particles, the volume of the hydrophilic binder being approximately equal to or more than the equivalent amount. The coating liquid containing the solid particles and or particulate oil and a hydrophilic binder is coated on a support having a method or the like to form 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.
[0054]
Examples of the inorganic fine particles used for the above purpose 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.
[0055]
The average particle diameter of the inorganic fine particles is determined by observing the particles themselves or the particles appearing on the cross section or surface of the void layer with an electron microscope, measuring the particle diameter of 1,000 arbitrary particles, and calculating the simple average value (number average) ). Here, the particle size of each particle is represented by a diameter assuming a circle equal to its projected area.
[0056]
As the inorganic fine particles, it is preferable to use solid fine particles selected from silica and alumina or alumina hydrate.
[0057]
As the silica that can be used in the present invention, silica synthesized by a usual wet method, colloidal silica or silica synthesized by a gas phase method is preferably used. Preferred is colloidal silica or fine particle silica synthesized by a gas phase method. Among them, fine particle silica synthesized by a gas phase method is a cationic polymer used not only for obtaining a high porosity but also for immobilizing a dye. It is preferable because coarse aggregates are less likely to be formed when added. The alumina or alumina hydrate may be crystalline or amorphous, and may have any shape such as irregular particles, spherical particles, and acicular particles.
[0058]
The inorganic fine particles are preferably in a state in which the fine particle dispersion before being mixed with the cationic polymer is dispersed to the primary particles.
[0059]
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.
[0060]
The most preferably used silica synthesized by a gas phase method having an average primary particle diameter 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 being easily suction-dispersed in water using, for example, a jet stream inductor mixer manufactured by Mitamura Riken Kogyo KK.
[0061]
In the present invention, a water-soluble binder can be used for the ink absorbing layer.
Examples of the water-soluble binder that can be used in the present invention include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyurethane, dextran, dextrin, carrageenan (κ, ι, λ, etc.), and agar. , Pullulan, water-soluble polyvinyl butyral, hydroxyethyl cellulose, carboxymethyl cellulose and the like. Two or more of these water-soluble binders can be used in combination.
[0062]
The water-soluble binder preferably used in the present invention is polyvinyl alcohol.
[0063]
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.
[0064]
As the polyvinyl alcohol obtained by hydrolyzing vinyl acetate, those having an average degree of polymerization of 1,000 or more are preferably used, and those having an average degree of polymerization of 1,500 to 5,000 are particularly preferably used. The saponification degree is preferably from 70 to 100%, particularly preferably from 80 to 99.5%.
[0065]
As the cation-modified polyvinyl alcohol, for example, as described in JP-A-61-10483, having a primary to tertiary amino group or quaternary ammonium group in the main chain or side chain of the polyvinyl alcohol Polyvinyl alcohol, which is obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.
[0066]
Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamido-2,2-dimethylethyl) ammonium chloride and trimethyl- (3-acrylamido-3,3-dimethylpropyl) ammonium chloride N-vinylimidazole, N-vinyl-2-methylimidazole, N- (3-dimethylaminopropyl) methacrylamide, hydroxylethyltrimethylammonium chloride, trimethyl- (2-methacrylamidopropyl) ammonium chloride, N- (1, 1-dimethyl-3-dimethylaminopropyl) acrylamide and the like.
[0067]
The ratio of the cation-modified group-containing monomer in the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol%, based on vinyl acetate.
[0068]
Anion-modified polyvinyl alcohol is, for example, a polyvinyl alcohol having an anionic group as described in JP-A-1-206088, as described in JP-A-61-237681 and JP-A-63-307979. Copolymers of vinyl alcohol and a vinyl compound having a water-soluble group, and modified polyvinyl alcohol having a water-soluble group as described in JP-A-7-285265.
[0069]
Examples of the nonionic modified polyvinyl alcohol include, for example, a polyvinyl alcohol derivative in which a polyalkylene oxide group is added to a part of vinyl alcohol as described in JP-A-7-9758, and JP-A-8-25795. And a block copolymer of a vinyl compound having a hydrophobic group and vinyl alcohol. Polyvinyl alcohol may be used in combination of two or more kinds such as different degrees of polymerization and types of modification.
[0070]
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 pigment, and the type of the water-soluble binder. ² The weight is usually 5 to 30 g, preferably 10 to 25 g.
[0071]
The mass ratio of the inorganic fine particles to the water-soluble binder used in the ink absorbing layer is usually from 2: 1 to 20: 1, and particularly preferably from 3: 1 to 10: 1.
[0072]
Further, the ink 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.
[0073]
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.
[0074]
In the void layer having an ink retaining ability, the void volume with respect to the solid content volume is called void ratio. In the present invention, it is preferable to set the porosity to 50% or more because voids can be efficiently formed without unnecessarily increasing the film thickness.
[0075]
As another type of the void type, in addition to forming an ink 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 absorbing layer may be formed using the applied coating liquid. In this case, the polyurethane resin emulsion is preferably a polyurethane resin emulsion having a polycarbonate chain, a polycarbonate chain and a polyester chain and having a particle size of 3.0 μm, and the polyurethane resin of the polyurethane resin emulsion is a polyol having a polycarbonate polyol, a polycarbonate polyol and a polyester polyol. And a polyurethane resin obtained by reacting an aliphatic isocyanate compound with a sulfonic acid group in the molecule, and further having an epichlorohydrin polyamide resin and a water-soluble epoxy compound and / or acetoacetylated vinyl alcohol. preferable. It is presumed that weak aggregation of cations and anions is formed in the ink-absorbing layer using the above-described polyurethane resin, and accordingly, voids having an ink-solvent absorbing ability are formed, so that an image can be formed.
[0076]
In the present invention, it is preferable to use a curing agent. The curing agent can be added at any time during the production of the ink jet recording medium, and may be added, for example, to the coating liquid for forming the ink absorbing layer.
[0077]
The ink absorbing layer according to the present invention is characterized in that the surface layer contains a thermoplastic resin, but preferably contains inorganic fine particles together with the thermoplastic resin.
[0078]
The surface layer referred to in the present invention is not limited to the outermost layer, and is not particularly limited as long as the effects of the present invention are exhibited. The recording medium according to the present invention, after image recording, for example, by melting and forming a thermoplastic resin contained in the surface layer by heating and pressurizing treatment, many of the effects of the present invention are exhibited, Even if the layer containing the plastic resin or the inorganic pigment and the thermoplastic resin is not the outermost layer, the constitution is applicable to the present invention. Particularly, when printing with a pigment ink, heating after image recording is performed. If the image quality, for example, glossiness and flatness, is improved by the presence or absence of pressure treatment, even if the layer containing the thermoplastic resin or the inorganic fine particles and the thermoplastic resin is not the outermost layer, the constitution is the same as that of the present invention. It corresponds to.
[0079]
Preferred examples of the structure for specifying the surface layer in the present invention are listed below, but the layer structure according to the present invention is not limited only to these.
[0080]
1: A structure in which a porous ink absorbing layer is provided on a support, and a layer containing a thermoplastic resin or inorganic fine particles and a thermoplastic resin thereon is the outermost layer.
2: A thin layer for the purpose of improving surface properties is provided on a layer having a void type ink absorbing layer on a support, on which a thermoplastic resin or inorganic fine particles and a thermoplastic resin are contained. Configuration provided
3: a porous ink absorbing layer on a support, on which a thermoplastic resin, or inorganic fine particles and a thermoplastic resin are contained, is provided with an ultraviolet absorbing function for the purpose of cutting off harmful light. With thin layer having
4: A structure in which a void type ink absorbing layer is provided on a support, and a layer containing a matting agent is provided on a layer containing a thermoplastic resin or inorganic fine particles and a thermoplastic resin thereon.
5: A structure in which a void-type ink absorbing layer is provided on a support, and a peelable layer is provided on a layer containing a thermoplastic resin or inorganic fine particles and a thermoplastic resin.
[0081]
The most preferable configuration among the above-described configuration examples is a case where the layer containing the inorganic fine particles and the thermoplastic resin according to the item 1, which can exert the effect of the present invention most, is the outermost layer.
[0082]
The surface layer containing the thermoplastic resin or the inorganic fine particles and the thermoplastic resin according to the present invention may contain a binder component and the like, if necessary, in addition to the inorganic fine particles and the thermoplastic resin.
[0083]
As the thermoplastic resin that can be used in the present invention, for example, polycarbonate, polyacrylonitrile, polystyrene, polyacrylic acid, polymethacrylic acid, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester, polyamide, polyether, These copolymers and their salts are mentioned. Among them, styrene-acrylate copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, SBR latex preferable. The thermoplastic resin may be a mixture of a plurality of polymers having different monomer compositions, particle diameters, and degrees of polymerization.
[0084]
In selecting a thermoplastic resin, consideration should be given to ink receptivity, glossiness of an image after fixing by heating and pressurizing, image fastness and releasability.
[0085]
Regarding the ink receptivity, when the particle size of the thermoplastic resin 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 viewpoint of the film strength of the inkjet recording medium after coating and drying and the deterioration of gloss. For this purpose, the preferred thermoplastic resin diameter is preferably 0.05 to 10 μm, and more preferably 0.1 to 5 μm. More preferably, it is 0.1 to 1 μm.
[0086]
In addition, as a criterion for selecting a thermoplastic resin, a glass transition point (Tg) can be mentioned. When Tg is lower than the application drying temperature, for example, the coating and drying temperature during the production of the recording medium is already higher than Tg, and the ink solvent permeates, so that the voids due to the thermoplastic resin disappear. If 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 melt and form a film after inkjet recording with the pigment ink, and the load on the apparatus and the support Is problematic in terms of thermal stability and the like. The preferred Tg of the thermoplastic resin is from 50 to 150C.
[0087]
The minimum film formation temperature (MFT) is preferably 50 to 150C.
The thermoplastic resin is preferably dispersed in an aqueous system from the viewpoint of environmental suitability, and particularly preferably is an aqueous latex obtained by emulsion polymerization. At this time, a type obtained by emulsion polymerization using a nonionic dispersant as an emulsifier is a form that can be preferably used. From the viewpoint of odor and safety, the thermoplastic resin used preferably has less residual monomer components, preferably 3% by mass or less, more preferably 1% by mass or less based on the solid content of the polymer. Preferably it is 0.1 mass% or less.
[0088]
The inorganic fine particles can be selected from the inorganic fine particles described in the above-mentioned void layer. Preferably, solid fine particles selected from silica and alumina or alumina hydrate are used, and silica is more preferable.
[0089]
The inorganic fine particles are preferably in a state in which the fine particle dispersion before being mixed with the cationic polymer is dispersed to the primary particles.
[0090]
The inorganic fine particles preferably have a particle size of 100 nm or less. For example, in the case of 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. Preferably it is 4 to 50 nm, most preferably 4 to 20 nm.
[0091]
In the present invention, the content ratio of the thermoplastic resin in the surface layer is preferably 40% by mass or more and 70% by mass or less. Furthermore, the solid content of the thermoplastic resin contained in the surface layer is 2 g / m2. ² Above, 20 g / m ² Or less, more preferably 2 to 15 g / m ² , More preferably 2.5 to 10 g / m ² Range. If the content ratio or solid content of the thermoplastic resin is too small, a sufficient film cannot be formed, and the pigment cannot be sufficiently dispersed in the film. For this reason, the image quality and gloss are not sufficiently improved. Further, if the content ratio or solid content of the thermoplastic resin is too large, the thermoplastic resin cannot be completely formed into a film in a short heating step, the fine particles remain as opaque and the image quality deteriorates, The absorption rate is also reduced, causing boundary bleeding, which is a problem.
[0092]
In the present invention, in the case of the surface layer containing the thermoplastic resin and the inorganic fine particles, the solid content mass ratio of the thermoplastic resin / the inorganic fine particles can be selected from the range of 90/10 to 10/90, and preferably 70/30 to 30/30. / 70, more preferably 60/40 to 40/60.
[0093]
In the present invention, the ink absorption capacity of the surface layer is 20 ml / m ² It is preferably at least 24 ml / m ² More than 40ml / m ² Or less, more preferably 24 ml / m ² Above, 35ml / m ² It is as follows.
[0094]
The surface layer coating liquid containing the inorganic fine particles and the thermoplastic resin may be a method in which the inorganic fine particles and the thermoplastic resin are dispersed at the same time, or a dispersion prepared and mixed at the time of preparing the coating liquid.
[0095]
Examples of the support that can be used in the present invention include supports conventionally used for ink jet recording media, for example, absorbent paper supports such as plain paper, art paper, coated paper and cast-coated paper, and plastic supports. The body, a non-absorbent support such as a paper support coated on both sides with a polyolefin, or a composite support obtained by laminating these can be appropriately selected and used.In the present invention, the support is made of paper. It is preferable that the resin is coated on both sides with resin, and that at least one type of resin that coats both sides of the paper is low-density polyethylene.
[0096]
Hereinafter, a paper support which can be preferably used in the present invention and in which both sides of the paper support are laminated with polyethylene or the like will be described.
[0097]
The base paper used for the paper support is made of wood pulp as a main raw material, and if necessary, is made of 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% by mass or more and 70% by mass or less.
[0098]
As the pulp, a chemical pulp containing less impurities (sulfate pulp or sulfite pulp) is preferably used, and pulp having improved whiteness by a bleaching treatment is also useful. Base paper contains sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc, and titanium oxide; paper strength agents such as starch, polyacrylamide, and polyvinyl alcohol; fluorescent whitening agents; and polyethylene glycols. , Etc., a water retention agent, a dispersant, a softening agent such as quaternary ammonium and the like can be added as appropriate.
[0099]
The freeness of the pulp used for papermaking is preferably 200 to 500 ml in accordance with the CSF standard, and the fiber length after beating is defined as the mass% of the 24 mesh residue and the 42 mesh residue as defined in JIS-P-8207. Is preferably 30 to 70%. In addition, it is preferable that the mass% of the 4 mesh residue is 20 mass% or less. The basis weight of the base paper is 30 to 250 g / m ² Is preferable, and especially 50 to 200 g / m ² Is preferred. The thickness of the base paper is preferably from 40 to 250 μm. The base paper may be calendered at the papermaking stage or after papermaking to provide high smoothness. Base paper density is 0.7-1.2g / m ² (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. A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, a sizing agent similar to the size that can be added to the base paper can be used. The pH of the base paper is preferably 5 to 9 when measured by a hot water extraction method specified in JIS-P-8113.
[0100]
The polyethylene that covers the front and back of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but in addition to LLDPE (linear low-density polyethylene) and polypropylene, etc. However, in the present invention, it is preferable that at least one kind is a low-density polyethylene.
[0101]
As the polyethylene layer on the ink absorbing layer side, it is preferable that rutile or anatase type titanium oxide is added to polyethylene to improve opacity and whiteness, as is widely used in photographic printing paper. The content of titanium oxide is usually from 3 to 20% by mass, and preferably from 4 to 13% by mass, based on polyethylene.
[0102]
Polyethylene-coated paper can be used as glossy paper, or when polyethylene is melt-extruded onto the base paper surface and coated, a so-called embossing process is performed to obtain a matte surface or silk surface that can be obtained with ordinary photographic printing paper. Those having a surface can also be used in the present invention.
[0103]
The amount of polyethylene used on the front and back of the base paper is selected so as to optimize the curl under low humidity and high humidity after providing the void layer and the back layer. 40 μm, and the back layer side is within a range of 10 to 30 μm.
[0104]
Further, the polyethylene-coated paper support preferably has the following properties.
[0105]
1. Tensile strength: strength specified by JIS-P-8113, preferably 20 to 300 N in the vertical direction and 10 to 200 N in the horizontal direction.
2. Tear strength: According to the method specified in JIS-P-8116, the vertical direction is preferably 0.1 to 20 N and the horizontal direction is preferably 2 to 20 N.
3. Compression modulus ≥ 98.1 MPa
4. 4. Surface Beck smoothness: Under conditions specified in JIS-P-8119, 20 seconds or more is preferable as a glossy surface, but may be less than this for so-called molded products. Surface roughness: The surface roughness specified in JIS-B-0601 is preferably not more than 10 μm per 2.5 mm of reference length.
6. Opacity: 80% or more, particularly preferably 85 to 98%, as measured by the method specified in JIS-P-8138.
7. Whiteness: L defined by JIS-Z-8729 ^* , A ^* , B ^* Is L ^* = 80-95, a ^* = -3 to +5, b ^* = −6 to +2
8. Surface gloss: A 60-degree specular gloss defined in JIS-Z-8741 is preferably 10 to 95%.
9. Clark rigidity: Clark rigidity in the conveyance direction of the recording medium is 50 to 300 cm. ² / 100 is preferred
10. Water content of middle paper: usually 2 to 100% by mass, preferably 2 to 6% by mass with respect to the middle paper
Next, the ink according to the present invention will be described.
[0106]
As the colorant used in the ink according to the present invention, a water-soluble dye, for example, an acid dye, a direct dye, a reactive dye, or a disperse dye, a pigment or the like can be used. Among them, a pigment is used as the colorant. It is preferable to use a pigmented ink.
[0107]
As the pigment in the pigment ink, organic pigments such as insoluble pigments and lake pigments, and carbon black can be preferably used.
[0108]
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.
[0109]
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.
[0110]
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.
[0111]
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.
[0112]
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.
[0113]
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.
[0114]
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.
[0115]
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.
[0116]
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.
[0117]
The water-based ink composition, which is a preferred form of the pigment ink, preferably uses a water-soluble organic solvent in combination.
[0118]
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.
[0119]
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.
[0120]
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.
[0121]
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.
[0122]
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.
[0123]
The viscosity of the ink composition during flight is preferably 40 mPa · s or less, more preferably 30 mPa · s or less.
[0124]
The surface tension of the ink composition during flight is preferably 20 mN / m or more, and more preferably 30 to 45 mN / m.
[0125]
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.
[0126]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.
[0127]
Example 1
<< 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.
[0128]
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.
[0129]
Embedded image

[0130]
(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.
[0131]
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)
After preparing the lower layer coating solution 1 and stirring at 43 ° C. for 30 minutes, the thermoplastic fine particles (acrylic latex, Tg 82 ° C., number average particle diameter 160 nm, solid content 40%) were mixed with the thermoplastic fine particles (B). / The filler (F: silica) was added over 15 minutes so that the solid content ratio (B / F) became 50/50, to prepare a coating solution 1 for the surface layer, and the mixture was filtered through a 10 μm filter. At 43 ° C. for 10 hours and used for coating.
[0132]
(Preparation of recording medium 1)
A paper support 1 coated on both sides with low-density polyethylene (LDPE) (thickness 220 μm, containing 13% by mass of anatase type titanium oxide with respect to polyethylene in polyethylene on the ink absorbing layer surface) and a first layer from the support side After the lower layer coating liquid 1 was applied by a slide hopper, the surface layer coating liquid 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. In the application, the lower layer had a silica coating amount of 18 g / m 2. ² The surface layer has a silica coating amount of 3 g / m2. ² I went to become. This recording medium 1 was processed into a roll shape having a roll width of 127 mm and a length of 100 m.
[0133]
《Preparation of ink》
(Preparation of pigment ink)
(Preparation of pigment dispersion)
<Preparation of Yellow Pigment Dispersion 1>

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.
[0134]
<Preparation of magenta pigment dispersion 1>

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.
[0135]
<Preparation of Cyan Pigment Dispersion 1>

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.
[0136]
<Preparation of Black Pigment Dispersion 1>

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.
[0137]
(Preparation of pigment ink)
<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 Nissin Chemical 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.
[0138]
<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 Nissin Chemical 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.
[0139]
<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 Nissin Chemical 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.
[0140]
<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 Nissin Chemical 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.
[0141]
<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 Nissin Chemical 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.
[0142]
<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 Nissin Chemical 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.
[0143]
<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 Nissin Chemical 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.
[0144]
<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 Nissin Chemical 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.
[0145]
<< Inkjet image formation >>
(Image printing)
Image printing was performed according to the following method under two printing conditions of normal temperature and normal humidity of 23 ° C. and 55% RH and high temperature and high humidity of 32 ° C. and 80% RH.
[0146]
The above-prepared pigment ink set is set in an ink jet printer having a heating / pressing roller pair for simultaneously performing the heating / pressing treatment shown in FIG. 8 types) 10ml / m ² And 20ml / m ² A solid image was printed under the following two conditions. At this time, the ejection conditions of the inks of the respective colors were adjusted so that the same ink droplet amount was ejected uniformly.
[0147]
(Drying of the formed image)
After ejecting the pigment ink onto the recording medium under the above conditions, a predetermined amount of the ink is applied using a commercially available dryer of 500 W from a distance of 5 cm from the printing surface so that the drying loss in the drying section is as shown in Table 1. The solvent was dried.
[0148]
(Heat and pressure treatment)
Next, a heating and pressing treatment was performed at a heating and pressing fixing device at a surface temperature of the fixing device of 105 ° C., a nip pressure of 1 MPa, and a linear velocity of 7 mm / s to form each image.
[0149]
Among the heating / pressing roller pairs, the heating / pressing roller arranged on the side in contact with the surface layer of the recording medium was a metal roller having a surface roughness of 100 nm, a halogen heater built-in, and a coating layer.
[0150]
<< Characteristic evaluation of formed image >>
For each solid image created by the above method, the C value was measured according to the following method, and the obtained results are shown in Table 1.
[0151]
The solid image prepared above was measured for reflection 60 degrees and mirror glossiness (C value%) at an optical comb of 2 mm using an image clarity measuring device ICM-1DP (manufactured by Suga Test Machine Co., Ltd.).
[0152]
[Table 1]

[0153]
As is clear from Table 1, after forming an image on a recording medium containing a thermoplastic resin in the surface layer, before heating and pressurizing treatment, evaporation and drying of a solvent equivalent to 10 to 50% by mass of the maximum ejection ink amount are performed. According to the present invention, as compared with the comparative example, both an image formed in a normal temperature and normal humidity environment and an image formed in a high temperature and high humidity environment could obtain an inkjet image having good gloss.
[0154]
Example 2
<< Preparation of recording medium >>
[Preparation of recording media 2 to 5]
In the paper support 1 (paper support coated on both sides with low-density polyethylene (LDPE)) used in the production of the recording medium 1 described in Example 1, the lamination material was changed to low-density polyethylene (LDPE). Recording media 2 to 5 were produced in the same manner except that the laminate material described in No. 2 was used. In addition, the coating amount of each laminate material was the same as that of the paper support 1.
[0155]
The details of each laminate material described in Table 2 are as follows.
LDPE: Low density polyethylene
HDPE: High density polyethylene
PP: polypropylene
PET: polyethylene terephthalate
<< Inkjet image formation >>
(Image printing)
Image printing was performed according to the following method in a printing environment of 23 ° C. and 55% RH at normal temperature and normal humidity.
[0156]
Similarly to Example 1, the pigment ink set described in Example 1 was set in an inkjet printer having a heating and pressing roller pair that simultaneously performs the heating and pressing processing illustrated in FIG. Supplied from the roll-shaped main volume, the maximum amount of ink to be discharged for all pigment inks (8 types) is 20 ml / m ² A solid image was printed under the following conditions. At this time, the ejection conditions of the inks of the respective colors were adjusted so that the same ink droplet amount was ejected uniformly.
[0157]
(Drying of the formed image)
After ejecting the pigment ink onto the recording medium under the above conditions, the ink solvent is dried using a 500 W commercial dryer from a distance of 5 cm from the printing surface so that the drying rate is 12% by mass in the drying section. The treatment was performed under the conditions that were performed and under the condition that drying was not performed at all.
[0158]
(Heat and pressure treatment)
Next, in the heating and pressing fixing device, the surface temperature of the fixing device was set to a condition of 5 ° C. lower than the melting temperature of the laminate material used for each recording medium, the nip pressure was 1 MPa, and the heating and pressing treatment was performed at a linear speed of 7 mm / s. Go and create each image.
[0159]
Among the heating / pressing roller pairs, the heating / pressing roller arranged on the side in contact with the surface layer of the recording medium was a metal roller having a surface roughness of 100 nm, a halogen heater built-in, and a coating layer.
[0160]
<< Characteristic evaluation of formed image >>
For each solid image created by the above method, the C value was measured according to the method described in Example 1, and the presence or absence of blisters and the feel (feel) were evaluated according to the following method. It is shown in FIG.
[0161]
(Blister evaluation)
The recording medium after the heat fixing treatment was visually observed for the occurrence of unevenness after the heat and pressure treatment.
[0162]
(Tactile sensation: evaluation of texture)
The recording medium after the heat fixing treatment is cut to a width of 10.2 cm and a length of 15.2 cm, and the end of the recording medium is held between fingers, and the strength of the waist and the flexibility of the recording medium are as follows. The sensory evaluation was performed according to the criteria described in 1.
[0163]
◎: Flexibleness and waist strength exactly equivalent to silver halide photographs (color paper)
○: The same flexibility and waist strength as silver halide photographs (color paper)
△: Compared to silver halide photographs (color paper), lacks flexibility and gives a sense of rigidity
×: Compared to silver halide photographs (color paper), the waist is too strong, lacks flexibility and gives a strong sense of discomfort
[0164]
[Table 2]

[0165]
As is clear from Table 2, after printing, apply a drying treatment equivalent to 12% by mass of the maximum amount of ink discharged, and apply heat and pressure fixing at a temperature equal to or lower than the melting point of the laminate material used for the paper support. As a result, an image having no gloss and high gloss could be obtained. Also, by using low-density polyethylene (LDPE) as the laminating material of the paper support, an ink-jet print having flexibility and stiffness similar to silver halide photographs (color paper) could be obtained.
[0166]
Example 3
<< Preparation of recording medium >>
[Preparation of recording media 6 to 11]
In the production of the recording medium 1 described in Example 1, the recording media 6 to 11 were prepared in the same manner except that the solid content ratio of the thermoplastic fine particles / filler (silica) in the surface layer was changed as shown in Table 3. Produced.
[0167]
<< Inkjet image formation >>
(Image printing)
Image printing was performed according to the following method in a printing environment of 23 ° C. and 55% RH at normal temperature and normal humidity.
[0168]
In the same manner as in Example 1, the pigment ink set described in Example 1 was set in an inkjet printer having a heating and pressing roller pair that simultaneously performs the heating and pressing processing illustrated in FIG. Supplied from the roll-shaped main volume, the maximum amount of ink to be discharged for all pigment inks (8 types) is 20 ml / m ² A solid image was printed under the following conditions. At this time, the ejection conditions of the inks of the respective colors were adjusted so that the same ink droplet amount was ejected uniformly.
[0169]
(Drying of the formed image)
After ejecting the pigment ink onto the recording medium under the above conditions, 500 W from a distance of 5 cm from the printing surface so that the drying rate and the drying rate (%) shown in Table 3 are obtained in the drying section after the drying conditions are not performed. Using a commercially available dryer, the ink solvent was dried at the same level.
[0170]
(Heat and pressure treatment)
Next, a heating and pressing treatment was performed at a heating and pressing fixing device at a surface temperature of the fixing device of 105 ° C., a nip pressure of 1 MPa, and a linear velocity of 7 mm / s to form each image.
[0171]
Among the heating / pressing roller pairs, the heating / pressing roller arranged on the side in contact with the surface layer of the recording medium was a metal roller having a surface roughness of 100 nm, a halogen heater built-in, and a coating layer.
[0172]
<< Characteristic evaluation of formed image >>
For each solid image created by the above method, the C value was measured according to the method described in Example 1, and the coating film quality after image formation was evaluated according to the following method. The obtained results are shown in Table 3. .
[0173]
(Evaluation of coating film quality)
The surface of the recording medium prepared above was visually observed and the state of the coating film was observed using a loupe, and the coating film quality was evaluated according to the following criteria.
[0174]
：: No more than image is recognized on the formed recording medium
Δ: Peeling of the film from the support and swelling of the surface layer are observed in a very small part, but within a practically acceptable range.
X: Clearly, peeling of the film from the support and swelling of the surface layer are recognized, and the quality is practically problematic.
[0175]
[Table 3]

[0176]
As is clear from Table 3, similar to the results of Examples 1 and 2, after printing, the level of the present invention in which the drying treatment was performed in an amount equivalent to 10 to 50% by mass of the maximum amount of ink discharged was higher than that of the comparative example. It can be seen that the gloss was excellent. Furthermore, by setting the ratio of the thermoplastic resin and the inorganic fine particles in the surface layer to be in the range of 40/60 to 70/30, in addition to evaporation of moisture and the like in the drying part, voids remain in the surface layer part even after the heat and pressure treatment. Is present, the ink solvent further diffuses and evaporates, whereby a stable coating film without film peeling or film swelling can be formed.
[0177]
【The invention's effect】
According to the present invention, it was possible to provide an ink jet recording method which is excellent in glossiness, flatness (blister resistance), texture (touch), and in which coating film peeling and image defects are reduced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an example of an ink jet recording apparatus having a drying unit and a heating and pressing roller that can be used in the present invention.
FIG. 2 is a schematic configuration diagram illustrating an example of an inkjet recording apparatus having a drying unit and a heating and pressing belt that can be 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 Fixing 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
8 Drying zone
9 Drying section
10 Dry wind

Claims (7)

An ink is applied to an inkjet recording medium having at least one ink-absorbing layer on a support, and a surface layer, which is an ink-absorbing layer farthest from the support, containing a thermoplastic resin. An ink jet recording method in which recording is performed, and thereafter, heating and pressurizing treatment is performed. An ink jet recording method comprising a drying step. The inkjet recording method according to claim 1, wherein the content ratio of the thermoplastic resin in the surface layer is 40% by mass or more and 70% by mass or less. 3. The ink jet recording method according to claim 1, wherein the support is a resin-coated paper in which both sides of the paper are coated with a resin. 4. The ink jet recording method according to claim 3, wherein at least one of the resins covering both sides of the paper is a low density polyethylene. 5. The ink jet recording method according to claim 3, wherein a heating temperature during the heating and pressurizing treatment is equal to or lower than a melting point of a resin coating both sides of the paper. Ink absorption capacity of the surface layer, the ink-jet recording method according to any one of claims 1 to 5, characterized in that 20 ml / m ² or more. The ink-jet recording method according to claim 1, wherein the ink is a pigment ink containing a pigment.

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