JP4296694B2 - Inkjet image forming method - Google Patents

Description

【００３２】
中心線平均粗さ（Ｒａ）の測定方法としては、２５℃、６５％ＲＨ環境下で測定試料同士が重ね合わされない条件で２４時間調湿したのち、該環境下で測定した。ここで示す重ね合わされない条件とは、例えば、支持体のエッジ部分を高くした状態で巻き取る方法や支持体と支持体の間に紙をはさんで重ねる方法、厚紙等で枠を作製しその四隅を固定する方法のいずれかである。用いることのできる測定装置としては、例えば、ＷＹＫＯ社製 ＲＳＴＰＬＵＳ非接触三次元微小表面形状測定システム等を挙げることができる。
【００３３】
本発明において規定した支持体表面の中心線平均粗さ（Ｒａ）として１．０〜５．０μｍを達成する方法としては、支持体表面をポリエチレン等で被覆する際に、その表面を、サイズあるいは形態が異なる規則的な凹凸を有するクーリングロールを用いて冷却しながら、ポリエチレン表面に種々の型付け処理を施すことにより、所望のＲａ値を有する支持体を得る方法を用いることを特徴とする。
【００３４】
本発明により得られる上記表面特性は、従来、インク吸収層で用いられているマット剤のみでは得ることができない。平坦なインク吸収層中に、公知のマット剤を含有させると、通常はインク吸収層表面に凸状態が形成される。マット剤により形成される凸形状のみで光沢度を所望の値の範囲にコントロールしようとすると、公知のマット剤よりかなり平均粒径の大きなマット剤を使用する必要が生じ、その結果、画像表面の光沢感が所望の範囲にコントロールできず、擦り傷がつきやすく、またプリント表面の触感を悪化させることとなり、本発明の効果が得られない。
【００３５】
本発明において、Ｒａが１μｍ未満ではぎらつき感が大きくなり、またＲａが５μｍより大きいと記録材料製造時のひび割れが発生し好ましくない。本発明において、Ｒａとしては１．０〜５．０μｍであるが、好ましくは１．０〜３．０μｍである。また、前記式１における乾燥膜厚ｄは、３．０〜６．０μｍであることを特徴とする。
【００３６】
本発明のインクジェット記録材料は、支持体及び最表層で本発明の熱可塑性樹脂からなるインク受容層を有するが、さらに色材とインク溶媒成分がインク受容層表面で分離したのちにインク溶媒成分が吸収される、熱可塑性樹脂層に隣接するインク溶媒吸収層（空隙層ともいう）を有することが好ましい。
【００３７】
本発明に係るインク受容層は、顔料インクによる画像記録後、加熱及び加圧を同時に行うことにより溶融し被膜化する熱可塑性微粒子により主に構成される。
【００３８】
本発明における熱可塑性微粒子としては、例えば、ポリカーボネート、ポリアクリロニトリル、ポリスチレン、ポリアクリル酸、ポリメタアクリル酸、ポリ塩化ビニル、ポリ塩化ビニリデン、ポリ酢酸ビニル、ポリエステル、ポリアミド、ポリエーテル及びこれらの共重合体が挙げられる。熱可塑性樹脂を選択するにあたり考慮すべき点は、インク受容性、加熱加圧による定着後の光沢性、及び画像堅牢性等がある。インク受容性については、熱可塑性微粒子が小さい場合は、顔料インク中の顔料粒子とインク溶媒の分離が遅くなり、実質的な吸収速度の低下を招くことになる。また、大きすぎる場合には、支持体上に塗設する際に隣接する溶媒吸収層との接着性や、塗設乾燥後の膜強度の点から好ましくない。このために好ましい熱可塑性微粒子径としては０．０５〜１０μｍ、より好ましくは０．１〜５μｍの範囲である。
【００３９】
また、熱可塑性微粒子の選択の基準としては、ガラス転移点Ｔｇが挙げられる。Ｔｇが極端に低い場合は、例えば、記録材料製造時の塗布乾燥温度が既にＴｇより高く、インク溶媒が透過するための熱可塑性微粒子による空隙が消失してしまう。また、Ｔｇが極端に高い場合は、顔料インクによるインクジェット記録後、溶融製膜するために高温での定着操作が必要となり、装置上の負荷及び支持体の熱安定性等が問題となる。熱可塑性微粒子の好ましいＴｇは５０〜１５０℃である。
【００４０】
また、画像形成後、記録画像はその経時保存による画質劣化をできるだけ抑制する必要がある。顔料インクを用いた場合は、染料インクの様な比較的短期間での濃度低下や変色を気にする必要はないが、未印字部の変色をできるだけ抑制する観点で熱可塑性微粒子を選択する必要がある。
【００４１】
本発明に係る最表層の熱可塑性樹脂層に隣接する顔料インクの溶媒吸収層は空隙が形成されていることが好ましいが、これは各種の無機固体微粒子を皮膜中に含有させることによって形成される。上記の目的で使用される無機微粒子としては、例えば、軽質炭酸カルシウム、重質炭酸カルシウム、炭酸マグネシウム、カオリン、クレー、タルク、硫酸カルシウム、硫酸バリウム、二酸化チタン、酸化亜鉛、水酸化亜鉛、硫化亜鉛、炭酸亜鉛、ハイドロタルサイト、珪酸アルミニウム、ケイソウ土、珪酸カルシウム、珪酸マグネシウム、合成非晶質シリカ、コロイダルシリカ、アルミナ、コロイダルアルミナ、擬ベーマイト、水酸化アルミニウム、リトポン、ゼオライト、水酸化マグネシウム等の白色無機顔料等が用いられる。無機微粒子の平均粒径は、粒子そのものあるいは空隙型のインク吸収層の断面や表面に現れた粒子を電子顕微鏡で観察し、１００個の任意粒子の粒径を求めてその単純平均値（個数平均）として求められる。ここで、個々の粒子の粒径は、その投影面積に等しい円を仮定したときの直径で表したものである。濃度の高い画像が形成される、鮮明な画像が記録できる、低コストで製造できる等の点からすると、固体微粒子として、気相法により合成された微粒子シリカ、コロイダルシリカ及びアルミナまたはアルミナ水和物から選ばれた固体微粒子を用いることが好ましい。アルミナまたはアルミナ水和物は、結晶性であっても非晶質であってもよく、また不定形粒子、球状粒子、針状粒子など任意の形状のものを使用することができる。現在、このような気相法によって合成された微粒子シリカは市販されており、市販の微粒子シリカには日本アエロジル社の各種のアエロジルがある。本発明の効果を得るためには、無機微粒子の粒径に特に制限はないが、１００ｎｍ以下が好ましく、空隙部を形成するために最も適する粒径は化合物によって異なる。例えば、上記気相法シリカの場合、１次粒子の状態で分散された無機微粒子の１次粒子の平均粒径（塗設前の分散液状態での粒径）では、４〜２０ｎｍが最も好ましく用いることができる。
【００４２】
また、インク溶媒吸収層としては、上記無機微粒子を用いる他に、例えば特開昭５９−１４８５８３号、同５５−５１５８３号、同５８−７２４９５号等に記載されている各種親水性樹脂とシリカとの配合液によりなるインク受容層、特開平９−１５０５７４号、同１０−１８１１８９号に記載されているアルキレンオキサイド含有又は、ポリカーボネイトを含有するウレタン樹脂エマルジョン等を用いることもできる。
【００４３】
本発明に係る記録材料の熱可塑性樹脂層及びインク溶媒吸収層において、空隙の総量（空隙容量）は、記録材料１ｍ²当り２０ｍｌ以上であることが好ましい。空隙容量が２０ｍｌ／ｍ²未満の場合、印字時のインク量が少ない場合に、インク吸収性は良好であるものの、インク量が多くなるとインクが完全に吸収されず、画質を低下させたり、乾燥性の遅れなどの問題が生じやすい。空隙容量の上限は特に制限されないが、空隙型のインク吸収層の膜厚を概ね５０μｍ以下にすることが、ひび割れ等の皮膜の物理特性を悪化させないためには必要で、この点からすると、空隙容量を４０ｍｌ／ｍ²以上とすることは難しい。
【００４４】
本発明において、空隙容量は、Ｊ．ＴＡＰＰＩの紙パルプ試験方法Ｎｏ．５１−８７紙及び板紙の液体吸収性試験方法（ブリストー法）に記載された方法で測定したとき、吸収時間２秒における液体転移量（ｍｌ／ｍ²）で表される。なお、上記の測定方法では、測定に純水（イオン交換水）が使用されているが、測定面積の判別を容易にするために、２％未満の水溶性染料を含有させてもよい。
【００４５】
本発明の記録材料のインク受容層である熱可塑性樹脂層、インク溶媒吸収層または空隙層、下引き層など必要に応じて適宜設けられる各種の構成層を支持体上に塗布する方法は、公知の方法から適宜選択して行うことが出来る。好ましい方法は、各層を構成する塗布液を支持体上に塗設して乾燥して得られる。この場合、２層以上を同時に塗布することもでき、特に全ての構成層を一回の塗布で済ます、同時塗布が好ましい。
【００４６】
塗布方式としては、ロールコーティング法、ロッドバーコーティング法、エアナイフコーティング法、スプレーコーティング法、カーテン塗布方法あるいは米国特許第２，６８１，２９４号公報記載のホッパーを使用するエクストルージョンコート法が好ましく用いられる。また、本発明に係るインクジェット記録材料の塗布に際して、塗布性を向上させるために増粘剤を用いてもよい。
【００４７】
請求項３に係る発明の熱ローラは、金属ローラ又はシリコンゴムローラにより構成されていることが特徴である。そのうち、金属ローラは、鉄やアルミニウムのような一般的な素材を用いればよく、熱耐久性を高める目的でテトラフルオロエチレンやポリテトラフルオロエチレン−パーフルオロアルキルビニルエーテル共重合体等により被覆されていてもよいし、定着後の平滑感を高めるために、鏡面仕上げされていてもよい。
【００４８】
本発明では、加熱及び加圧時に、５０〜１５０℃で加熱することを特徴とする。請求項４に係る発明では、ローラがその内部に熱源を内蔵しており、この熱源は線状のヒータを有し、ローラの表面温度を５０〜１５０℃に加熱させるものであることが好ましい。本発明に係る熱ローラにおいて、上下ローラ間に圧力を加え、ローラを変形させ、いわゆるニップを形成する。請求項５に係る発明では、ニップ幅としては１〜２０ｍｍとすることが特徴であり、好ましくは１．５〜７ｍｍである。なお、一対のローラを用いる場合、少なくとも一方のローラに熱源を有していればよい。
【００４９】
本発明に係る圧力は、１平方センチメートル当たり２０〜５００Ｎ必要だが、これより圧力が低いと加熱加圧により顔料粒子が熱可塑性樹脂層に十分に押し込まれず、また圧力が高すぎると顔料粒子の押し込みは十分だが、平滑性、光沢性が高すぎ、ぎらついた画像となる。
【００５０】
本発明の顔料インクにおいて、顔料の分散安定性を向上するため界面活性剤を含有させることが好ましい。本発明のインクに好ましく使用される界面活性剤としては、ジアルキルスルホコハク酸塩類、アルキルナフタレンスルホン酸塩類、脂肪酸塩類等のアニオン性界面活性剤、ポリオキシエチレンアルキルエーテル類、ポリオキシエチレンアルキルアリルエーテル類、アセチレングリコール類、ポリオキシエチレン・ポリオキシプロピレンブロックコポリマー類等のノニオン性界面活性剤、アルキルアミン塩類、第四級アンモニウム塩類等のカチオン性界面活性剤が挙げられる。特にアニオン性界面活性剤およびノニオン性界面活性剤を好ましく用いることができる。
【００５１】
本発明に使用できる顔料としては、従来公知の有機及び無機顔料が使用できる。例えばアゾレーキ、不溶性アゾ顔料、縮合アゾ顔料、キレートアゾ顔料等のアゾ顔料や、フタロシアニン顔料、ペリレン及びペリレン顔料、アントラキノン顔料、キナクリドン顔料、ジオキサンジン顔料、チオインジゴ顔料、イソインドリノン顔料、キノフタロニ顔料等の多環式顔料や、塩基性染料型レーキ、酸性染料型レーキ等の染料レーキや、ニトロ顔料、ニトロソ顔料、アニリンブラック、昼光蛍光顔料等の有機顔料、カーボンブラック等の無機顔料が挙げられる。
【００５２】
具体的な有機顔料を以下に例示する。
マゼンタまたはレッド用の顔料としては、Ｃ．Ｉ．ピグメントレッド２、Ｃ．Ｉ．ピグメントレッド３、Ｃ．Ｉ．ピグメントレッド５、Ｃ．Ｉ．ピグメントレッド６、Ｃ．Ｉ．ピグメントレッド７、Ｃ．Ｉ．ピグメントレッド１５、Ｃ．Ｉ．ピグメントレッド１６、Ｃ．Ｉ．ピグメントレッド４８：１、Ｃ．Ｉ．ピグメントレッド５３：１、Ｃ．Ｉ．ピグメントレッド５７：１、Ｃ．Ｉ．ピグメントレッド１２２、Ｃ．Ｉ．ピグメントレッド１２３、Ｃ．Ｉ．ピグメントレッド１３９、Ｃ．Ｉ．ピグメントレッド１４４、Ｃ．Ｉ．ピグメントレッド１４９、Ｃ．Ｉ．ピグメントレッド１６６、Ｃ．Ｉ．ピグメントレッド１７７、Ｃ．Ｉ．ピグメントレッド１７８、Ｃ．Ｉ．ピグメントレッド２２２等が挙げられる。
【００５３】
オレンジまたはイエロー用の顔料としては、Ｃ．Ｉ．ピグメントオレンジ３１、Ｃ．Ｉ．ピグメントオレンジ４３、Ｃ．Ｉ．ピグメントイエロー１２、Ｃ．Ｉ．ピグメントイエロー１３、Ｃ．Ｉ．ピグメントイエロー１４、Ｃ．Ｉ．ピグメントイエロー１５、Ｃ．Ｉ．ピグメントイエロー１７、Ｃ．Ｉ．ピグメントイエロー９３、Ｃ．Ｉ．ピグメントイエロー９４、Ｃ．Ｉ．ピグメントイエロー１３８等が挙げられる。
【００５４】
グリーンまたはシアン用の顔料としては、Ｃ．Ｉ．ピグメントブルー１５、Ｃ．Ｉ．ピグメントブルー１５：２、Ｃ．Ｉ．ピグメントブルー１５：３、Ｃ．Ｉ．ピグメントブルー１６、Ｃ．Ｉ．ピグメントブルー６０、Ｃ．Ｉ．ピグメントグリーン７等が挙げられる。
【００５５】
本発明において用いる顔料インクには、必要に応じて顔料分散剤を含有させてもよい。使用できる顔料分散剤としては、例えば、高級脂肪酸塩、アルキル硫酸塩、アルキルエステル硫酸塩、アルキルスルホン酸塩、スルホコハク酸塩、ナフタレンスルホン酸塩、アルキルリン酸塩、ポリオキシアルキレンアルキルエーテルリン酸塩、ポリオキシアルキレンアルキルフェニルエーテル、ポリオキシエチレンポリオキシプロピレングリコール、グリセリンエステル、ソルビタンエステル、ポリオキシエチレン脂肪酸アミド、アミンオキシド等の活性剤、あるいはスチレン、スチレン誘導体、ビニルナフタレン誘導体、アクリル酸、アクリル酸誘導体、マレイン酸、マレイン酸誘導体、イタコン酸、イタコン酸誘導体、フマル酸、フマル酸誘導体から選ばれた２種以上の単量体からなるブロック共重合体、ランダム共重合体およびこれらの塩をあげることができる。
【００５６】
顔料の分散方法としては、例えば、ボールミル、サンドミル、アトライター、ロールミル、アジテータ、ヘンシェルミキサ、コロイドミル、超音波ホモジナイザー、パールミル、湿式ジェットミル、ペイントシェーカー等各種を用いることができる。
【００５７】
本発明の顔料分散体の粗粒分を除去する目的で遠心分離装置を使用すること、フィルターを使用することも好ましく用いられる。
【００５８】
本発明のインクに使用する顔料分散体の平均粒径は、１０ｎｍ以上２００ｎｍ以下であることが好ましく、１０ｎｍ以上１００ｎｍ以下がより好ましく、１０ｎｍ以上５０ｎｍ以下がさらに好ましい。顔料分散体の平均粒径が１００ｎｍを越えると、光沢タイプの記録材料に記録した画像では光沢感の劣化が生じる。また、顔料分散体の平均粒径が１０ｎｍ未満になると顔料分散体の安定性が悪くなりやすく、インクの保存安定性が劣化しやすくなる。
【００５９】
顔料分散体の粒径測定は、光散乱法、電気泳動法、レーザードップラー法等を用いた市販の粒径測定機器により求めることが出来る。また、透過型電子顕微鏡による粒子像撮影を少なくとも１００粒子以上に対して行い、この像をＩｍａｇｅ−Ｐｒｏ（メディアサイバネティクス製）等の画像解析ソフトを用いて統計的処理を行うことによっても求めることが可能である。
【００６０】
本発明におけるインクには、ラテックスを含有しても良い。本発明におけるラテックスとは媒質中に分散状態にあるポリマー粒子のことを指す。ポリマーの種類としては、例えば、スチレン−ブタジエン共重合体、ポリスチレン、アクリロニトリル−ブタジエン共重合体、アクリル酸エステル共重合体、ポリウレタン、シリコン−アクリル共重合体およびアクリル変性フッ素樹脂等があるが、なかでもアクリル酸エステル、ポリウレタンおよびシリコン−アクリル共重合体が好ましい。
【００６１】
ラテックスの製造において、用いられる乳化剤としては、低分子量の界面活性剤が一般的であるが、高分子量の界面活性剤（例えば、可溶化基がポリマーにグラフト結合しているタイプや可溶化基を持つ部分と不溶性の部分を連結させたブロックポリマーのタイプ等がある）を乳化剤として用いることができる。また、可溶化基をラテックスの中心ポリマーに直接結合させることにより乳化剤を用いずに分散されているラテックスも存在する。上記のような乳化剤として高分子量の界面活性剤を用いるラテックスおよび乳化剤を使用しないラテックスは、ソープフリーラテックスと呼ばれている。本発明に使用するラテックスとしては、乳化剤の種類、形態を問わないが、インクの保存安定性に優れるソープフリーラテックスを用いることがより好ましい。
【００６２】
また、最近は中心ポリマーが均一であるラテックス以外にポリマー粒子の中心部と外縁部で組成を異にしたコア・シェルタイプのラテックスも存在するが、このタイプのラテックスも好ましく用いることができる。
【００６３】
本発明におけるラテックスの平均粒径は１５０ｎｍ以下が好ましく、５０ｎｍ以下がより好ましい。
【００６４】
ラテックスの平均粒子径は光散乱方式やレーザードップラー方式を用いた市販の測定装置を使用して簡便に計測することが可能である。
【００６５】
本発明におけるラテックスの固形分添加量は、インクの全質量に対して０．１質量％以上１０質量％以下が好ましく、０．３質量％以上５質量％以下であることが特に好ましい。添加量０．１質量％未満では耐水性に関して十分な効果を発揮することが難しく、また１０質量％を越えると経時でインク粘度の上昇や顔料分散粒径の増大が起こりやすいなどインク保存性の点で問題が生じることが多い。
【００６６】
本発明においては電気伝導度調節剤を用いることもでき、例えば塩化カリウム、塩化アンモニウム、硫酸ナトリウム、硝酸ナトリウム、塩化ナトリウムなどの無機塩や、トリエタノールアミン等の水性アミン等が挙げられる。
【００６７】
本発明のインク及び必要に応じて設けられる構成層においては、吐出安定性、プリントヘッドやインクカートリッジ適合性、保存安定性、画像保存性、その他の諸性能向上の目的に応じて、さらに粘度調整剤、比抵抗調整剤、皮膜形成剤、紫外線吸収剤、酸化防止剤、退色防止剤、防錆剤、防腐剤等を添加することもでき、例えば、ポリスチレン、ポリアクリル酸エステル類、ポリメタクリル酸エステル類、ポリアクリルアミド類、ポリエチレン、ポリプロピレン、ポリ塩化ビニル、ポリ塩化ビニリデン、またはこれらの共重合体、尿素樹脂、またはメラミン樹脂等の有機ラテックス微粒子、流動パラフィン、ジオクチルフタレート、トリクレジルホスフェート、シリコンオイル等の油滴微粒子、カチオンまたはノニオンの各種界面活性剤、特開昭５７−７４１９３号公報、同５７−８７９８８号公報及び同６２−２６１４７６号公報に記載の紫外線吸収剤、特開昭５７−７４１９２号、同５７−８７９８９号公報、同６０−７２７８５号公報、同６１−１４６５９１号公報、特開平１−９５０９１号公報及び同３−１３３７６号公報等に記載されている退色防止剤、特開昭５９−４２９９３号公報、同５９−５２６８９号公報、同６２−２８００６９号公報、同６１−２４２８７１号公報および特開平４−２１９２６６号公報等に記載されている蛍光増白剤、硫酸、リン酸、クエン酸、水酸化ナトリウム、水酸化カリウム、炭酸カリウム等のｐＨ調整剤、消泡剤、防腐剤、増粘剤、帯電防止剤、マット剤等の公知の各種添加剤を含有させることもできる。
【００６８】
本発明のインクジェット記録方法で使用するインクジェットヘッドはオンデマンド方式でもコンティニュアス方式でも構わない。また吐出方式としては、電気−機械変換方式（例えば、シングルキャビティー型、ダブルキャビティー型、ベンダー型、ピストン型、シェアーモード型、シェアードウォール型等）、電気−熱変換方式（例えば、サーマルインクジェット型、バブルジェット型等）、静電吸引方式（例えば、電界制御型、スリットジェット型等）及び放電方式（例えば、スパークジェット型等）などを具体的な例として挙げることができるが、いずれの吐出方式を用いても構わない。
【００６９】
【実施例】
以下に実施例を挙げて本発明を具体的に説明するが、本発明はこれらの実施態様に限定されるものではない。尚、実施例中での％表示は、特に断りのない限り質量％を表す。
【００７０】
実施例１
《支持体の作製》
含水率が６．５％で坪量が１７０ｇ／ｍ²の写真用原紙の裏面側に、押し出し塗布法により、密度が０．９２の低密度ポリエチレンを３０μｍの厚さで塗布した。ついで、表面側にアナターゼ型酸化チタン５．５％を含有する密度が０．９２の低密度ポリエチレンを３５μｍの厚さで溶融押し出し塗布法で塗布して両面をポリエチレンで被覆した支持体を作製した。溶融押し出し塗布直後に、表面に種々の規則的な凸凹の高さを有するクーリングロールを使用して冷却しながらポリエチレン表面に種々の型付け処理を施した。型付けの違いは、密度及び凸凹の高さを調整することで行った。表面にコロナ放電を行い、ゼラチン下引き層を０．３ｇ／ｍ²になるように塗布した。以上のようにして作製した各種の型付け違いの支持体１〜６の各表面の中心線平均粗さを、下記記載の方法にて測定し、得られた結果を、後述の表１に記載した。
【００７１】
（支持体表面の中心線平均粗さの測定）
上記作製した各支持体表面の中心線表面粗さを下記に示す方法により測定した。中心線平均粗さＲａ（μｍ）は、非接触３次元表面解析装置（ＷＹＫＯ社ＲＳＴ／ＰＬＵＳ）を用いて測定した。なおＲａの定義は、ＪＩＳ表面粗さ（Ｂ０６０１）に従った。測定は、３０ｃｍ×３０ｃｍの各試料について、３ｃｍ間隔で碁盤目上に１００分割し、各正方形領域の中心について測定を行ない、１００回の測定からその平均値と標準偏差を求めた。中心線平均粗さ（Ｒａ）は、得られた粗さ曲線からその中心線の方向に測定長さ２．５ｍｍの部分を抜き取り、カットオフ値を０．８ｍｍとして、この抜き取り部分の中心線をＸ軸、縦倍率の方向をＹ軸、粗さ曲線をＹ＝ｆ（Ｘ）で表したとき、前記式（数１）によって求められる値をマイクロメートル（μｍ）で表した。
【００７２】
《酸化チタン分散液−１の調製》
平均粒径が０．２５μｍの酸化チタン（石原産業：Ｗ−１０）２０ｋｇを、ｐＨ７．５のトリポリリン酸ナトリウムを１５０ｇ、ポリビニルアルコール（クラレ株式会社：ＰＶＡ２３５、平均重合度３５００）を５００ｇ、カチオン性ポリマー（Ｐ−１）を１５０ｇ及びサンノブコ株式会社の消泡剤ＳＮ３８１を１０ｇ含有する水溶液９０リットルに添加し、高圧ホモジナイザー（三和工業株式会社製）で分散した後、全量を１００リットルに仕上げ、均一な酸化チタン分散液−１を得た。
【００７３】
《シリカ分散液−１の調製》
１次粒子の平均粒径が０．００７μｍの気相法シリカ（日本アエロジル工業株式会社：Ａ３００）１２５ｋｇを三田村理研工業株式会社製のジェットストリーム・インダクターミキサーＴＤＳを用いて、硝酸でｐＨ２．５に調整した６２０リットルの純水中に室温で吸引分散した後に、全量を６９４リットルに純水で仕上げた。この分散液を希釈し、シリカ粒子を電子顕微鏡写真で撮影したところ、ほとんどの粒子が０．０１μｍ以下の粒径であり、１次粒子まで分散されていることを確認した。ここで言うほとんどの粒子とは８５〜９０％を占める粒子のことをいう。
【００７４】
《シリカ分散液−２の調製》
カチオン性ポリマー（Ｐ−２）を１．４１ｋｇ及びエタノール４．２リットルを含有するｐＨが２．３の水溶液１８リットルに、２５〜３０℃の温度範囲で、上記シリカ分散液−１の６９．４リットルを攪拌しながら２０分かけ添加し、ついでホウ酸２６０ｇとホウ砂２３０ｇを含むｐＨが７．３の水溶液７．０リットルを約１０分かけて添加し、次いで消泡剤ＳＮ３８１を１ｇ添加した。この混合液を、三和工業株式会社製高圧ホモジナイザーで２４．５ＭＰａの圧力で２回分散し、全量を純水で９７リットルに仕上げ、ほぼ透明な平均粒径が０．００７μｍのシリカ分散液−２を調製した。
【００７５】
【化１】

【００７６】
《インク溶媒吸収層用塗布液の調製及び塗布》
第１層、第２層、第３層の塗布液を、以下の手順で調製、塗布し、インク溶媒吸収層を形成した。
【００７７】
〈第１層用塗布液〉
シリカ分散液−１の６００ｍｌに、４０℃で攪拌しながら以下の添加剤を順次混合した。
【００７８】
ポリビニルアルコール（クラレ工業株式会社製：ＰＶＡ２３５
平均重合度：３５００）の７％水溶液 １９４．６ｍｌ
酸化チタン分散液−１ ３３ｍｌ
ラテックスエマルジョン・ＡＥ−８０３：昭和高分子株式会社製 １８ｍｌ
純水で全量を１０００ｍｌに仕上げる。塗布液ｐＨは４．４であった。
【００７９】
〈第２層用塗布液〉
シリカ分散液−２の６５０ｍｌに、４０℃で攪拌しながら以下の添加剤を順次混合した。
【００８０】
ポリビニルアルコール（クラレ工業株式会社製：ＰＶＡ２３５
平均重合度：３５００）の７％溶液 ２０１．６ｍｌ
純水で全量を１０００ｍｌに仕上げる。塗布液ｐＨは４．４であった。
【００８１】
〈第３層塗布液〉
シリカ分散液−２の６５０ｍｌに、４０℃で攪拌しながら以下の添加剤を順次混合した。
【００８２】
ポリビニルアルコール（クラレ工業株式会社製：ＰＶＡ２３５
平均重合度：３５００）の７％水溶液 ２０１．６ｍｌ
シリコン分散液（東レ・ダウコーニング・シリコーン株式会社製：
ＢＹ−２２−８３９） １５ｍｌ
サポニン５０％水溶液 ４ｍｌ
純水で全量を１０００ｍｌに仕上げる。塗布液のｐＨは４．５であった。
【００８３】
上記のようにして調製した各塗布液を、下記のフィルターで濾過した。
第１層と第２層：東洋濾紙株式会社製ＴＣＰ１０で２段濾過
第３層：東洋濾紙株式会社製ＴＣＰ３０で２段濾過
〈第１層〜第３層の塗布〉
ついで、前記の各支持体に第１層（５０μｍ）、第２層（１００μｍ）、第３層（５０μｍ）の順になるように各層を塗布した。括弧内はそれぞれ湿潤膜厚を示し、第１層〜第３層は同時塗布した。
【００８４】
塗布は、それぞれの塗布液を４０℃で３層式スライドホッパーで塗布を行い、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、試料を巻き取りインク溶媒吸収層のみの記録材料１〜６を得た。
【００８５】
《熱可塑性樹脂層用塗布液の調製、塗布》
次に、以下の処方により熱可塑性樹脂層用の塗布液を調製した。
【００８６】
ＡＴ−２０００（スチレン−アクリル酸共重合ラテックス Ｔｇ：８０℃、
ＭＦＴ：８５℃（株）昭和高分子製） ５０％
ＡＳ−７１８０（アクリル系共重合体Ｎａ塩水溶液
（株）東亞合成化学工業製） ３％
水 ４７％
前記溶媒吸収層のみ有する記録材料１〜６上に、上記熱可塑性樹脂層用の塗布液をスライドホッパーで乾燥膜厚として表１記載の値となるように塗布を行い、上記と同様の条件で乾燥を行って、記録材料１０１〜１１４を作製した。
【００８７】
《記録材料への画像記録》
（イエロー顔料分散体の調製）
Ｃ．Ｉ．ピグメントイエロー１２８ １５０ｇ
スチレン−アクリル−メタクリル酸メチル共重合体（分子量１０，０００、
酸価１６０） ７０ｇ
エチレングリコール １００ｇ
グリセリン ８０ｇ
イオン交換水 ２００ｇ
を混合し、０．３ｍｍのジルコニアビーズで体積率６０％充填した横型ビーズミル（アシザワ（株）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を得た。得られたイエロー顔料分散体の平均粒径は１２５ｎｍであった。なお、顔料インク分散体平均粒径の測定は、ゼータサイザー１０００（マルバーン社製）を用いた。
【００８８】
（マゼンタ顔料分散体の調製）
Ｃ．Ｉ．ピグメントレッド１２２ １００ｇ
デモールＣ ６３ｇ
グリセリン １００ｇ
イオン交換水 １３０ｇ
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（株）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を得た。得られたマゼンタ顔料分散体の平均粒径は６５ｎｍであった。
【００８９】
（シアン顔料分散体の調製）
Ｃ．Ｉ．ピグメントブルー１５：３ １００ｇ
デモールＣ ６３ｇ
ジエチレングリコール １００ｇ
イオン交換水 １２５ｇ
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（株）製システムゼータミニ）を用いて分散した後、２０，０００ｒｐｍで３０分間遠心分離処理を行い、シアン顔料分散体を得た。得られたシアン顔料分散体の平均粒径は５５ｎｍであった。
【００９０】
（ブラック顔料分散体の調製）
Ｈｏｓｔｆｉｎｅ Ｂｌａｃｋ Ｔ（クラリアント（株）製、
平均粒径５０ｎｍ） １６７ｇ
ラテックス４（スーパーフレックス４６０、第一工業製薬（株）製）７８．９ｇ
エチレングリコール ２００ｇ
トリエチレングリコールモノメチルエーテル １２０ｇ
オルフィンＧＸＬ（日信化学（株）製） ４ｇ
プロキセルＧＸＬ（ゼネカ社製） ２ｇ
以上をイオン交換水で１０００ｇに仕上げ、１μｍのミリポアフィルターを２度通過させて顔料インクを調製した。
【００９１】
《記録材料への画像記録及び評価》
上記作製した記録材料１０１〜１１４を対し、ノズル粒径２０μｍ、駆動周波数１２ｋＨｚ、１色当りのノズル数１２８、同色ノズル密度１８０ｄｐｉ（本発明でいうｄｐｉとは、２．５４ｃｍ当たりのドットの数を表す）であるピエゾ型ヘッドを搭載し、最大記録密度７２０×７２０ｄｐｉのオンデマンド型のインクジェットを使用して、上記顔料インクにより各色の均一ベタ画像パターンをイエロー、マゼンタ、シアン、ブラックの各色について作製した。
【００９２】
続いて、記録材料１０１〜１０９に対して、上記画像パターンを付与したサンプルについて、直径３０ｍｍφの円柱状の鉄シリンダ（上ローラ）と、シリコンゴムローラ（直径３０ｍｍφの下ローラ）が共に、テトラフロオロエチレン−パーフルオロアルキルエーテル共重合体により被覆され、鉄シリンダ内にヒータを内蔵されている定着装置を用いて、線圧１００Ｎ／ｃｍ²、ニップ幅４．３ｍｍ、線速１０ｍｍ／ｓ、加熱温度１００℃の条件で加熱及び加圧処理を行った。
【００９３】
記録材料１１０は、画像記録後、定着装置を用いず、１００℃で１０分間の加熱処理のみを行った。
【００９４】
記録材料１１１は、画像記録後、１００℃で１０分間加熱処理を施した後、上記定着装置を用いて加圧処理を行った。
【００９５】
記録材料１１２は、加熱及び加圧を上記定着装置を用いて同時に行ったが、定着にはテトラフルオロアルキルエーテル共重合体を被覆した鉄ローラを２本組み合わせて、実質的にニップ幅がない条件にて定着処理を行った。
【００９６】
記録材料１１３は、画像記録後、記録材料１０１〜１０９と同様の定着処理を行ったが、定着温度を１７０℃とした。
【００９７】
記録材料１１４は、画像記録後、記録材料１０１〜１０９と同様の定着処理を行ったが、定着時の線圧を５Ｎ／ｃｍ²とした。
【００９８】
上記処理により作製した各記録画像について、印字部と未印字部の光沢差及び印字部のブロンズについて、下記に示す基準に則り、目視評価を行い、得られた結果を、同じく表１に示す。
【００９９】
〈印字部と未印字部の光沢差〉
◎：光沢差はほとんど感じられない
○：やや光沢差は認められるが、実用上問題はない
△：実用上問題のある光沢差がある
×：著しく大きな光沢差がある
〈ブロンズ〉
◎：ブロンズがほとんど感じられない
○：ややブロンズは認められるが、実用上は問題ない
△：実用上問題のあるブロンズがみられる
×：著しいブロンズがみられる
【０１００】
【表１】

【０１０１】
表１の結果より明らかなように、試料１０３及び試料１０６〜１０９は、印字部と未印字部の光沢差が大きく、ブロンズもみられ、実用上問題であるプリントしか得られないのに対して、本発明の記録材料１０１（ｄ／Ｒａ＝２．４）、記録材料１０２（ｄ／Ｒａ＝２．７８）、記録材料１０４（ｄ／Ｒａ＝１．０８）及び記録材料１０５（ｄ／Ｒａ＝２．７８）はいずれも印字部と未印字部の光沢差がなく、ブロンズの改良効果が大きく、高級感のある画像が得られていることがわかる。
【０１０２】
また、記録材料の作製条件は記録材料１０１と同じで、印字後加熱のみ行った記録材料１１０、記録材料の作製条件は記録材料１０４と同じで、加熱後に加圧を行った記録材料１１１については、いずれも印字部と未印字部の光沢差を解消できず、またブロンズの発生も認められ、本発明に係る加熱及び加圧を同時に行う効果の有効性が確認できた。
【０１０３】
また、画像記録後に金属ローラを組み合わせて、実質的にニップ幅がない条件で定着させた記録材料１１２、定着時の温度を１７０℃とした記録材料１１３及び画像記録後の定着時の圧力を１平方センチ当たり５Ｎとした記録材料１１４は、いずれも印字部の光沢がやや高く、ブロンジングも完全には解消されてはいないが、実用上は問題のないレベルにある。
【０１０４】
【発明の効果】
実施例で実証した如く、本発明による画像形成方法は、顔料インクを用いてインクジェット記録を行った場合の印字部と未印字部の顕著な光沢差を生じることなく、ブロンズが抑えられた高級感のあるインクジェット記録画像を得ることができた。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming method in which a transparent treatment is performed by heating and pressurizing after recording with a pigment ink on a thermoplastic resin layer, and more specifically, the glare caused by surface gloss is improved so that no gloss difference is produced in the image. The present invention relates to an inkjet image forming method for obtaining a high-quality inkjet recorded image.
[0002]
[Prior art]
Inkjet recording is a method in which micro droplets of ink are ejected by various operating principles and deposited on recording materials to form images such as images and characters. Has the advantage of being easy. In addition, due to recent technological advances, high image quality approaching silver salt photographs of ink-jet prints using dye inks and lower prices of devices are further accelerating their spread.
[0003]
Dyes used in inkjet printing are mainly soluble in a solvent, and pigment molecules are colored in a molecular state or a cluster state. Therefore, since the environment of each molecule is similar, its absorption spectrum is sharp, and it shows a clear color with high purity. Furthermore, these dyes have no particle property, and as a result, no scattered light or reflected light is generated, so that the transparency is high and the hue is clear.
[0004]
On the other hand, however, when the dye molecules are destroyed by a photochemical reaction or the like, the decrease in the number of molecules reflects the color density as it is, so that the light resistance is poor. In this way, ink-jet recorded images using dye ink have high image quality, but the image quality is greatly deteriorated by storage over time, and the technology that surpasses silver salt photography has not yet emerged from the viewpoint of image storage stability. It is.
[0005]
In contrast to dye inks, pigment inks that use pigments with good light resistance as colorants are used as inks for applications that require images that are resistant to fading due to light. The pigment is insoluble in the solvent, and the dye molecule contributes to coloring in a state where particles are formed and dispersed in the solvent. Even if the surface molecules are destroyed by photochemical reaction etc., there is a new dye molecule layer at the bottom, so there is little apparent reduction in coloring power, and it has excellent image storability. Due to the influence of scattered light and reflected light, the glossiness is significantly deteriorated. In addition, there is a phenomenon called bronze as a characteristic phenomenon when a pigment is used as a coloring material. This phenomenon means bronze (gloss) that appears on the surface in addition to the original color of the pigment, and is often problematic. As the hue of this bronze, the original extra color of the pigment usually appears. For example, bronzes such as Blue → Red, Green → Violet, Red → Yellow, Yellow → Blue Green are expressed.
[0006]
The most prominent example of such a bronze phenomenon is so-called metallic luster. There are two types of metallic luster: interfacial bronze and interference bronze. Interfacial bronze is a phenomenon caused by the ratio of the wavelength component of the absorption band of the pigment in the reflected light due to the selective reflection of light on the particle surface. On the other hand, interference bronze is caused by selective interference of reflected light from an approaching substance. Usually, the bronze of the pigment is mainly interfacial bronze.
[0007]
Japanese Patent Application Laid-Open No. 11-208097 discloses a technique for moving pigment particles into a thermoplastic resin layer after recording an image with a pigment ink containing no dispersant on a recording material whose outermost layer is a thermoplastic resin layer. . After the pigment ink is attached to the surface of the recording material, the pigment particles are present on the surface of the thermoplastic resin layer, and the solvent component is absorbed by each layer constituting the recording material. Subsequently, by moving the pigment particles into the thermoplastic resin layer, the floating of the printed portion peculiar to the pigment ink with respect to the unprinted portion is eliminated, and the gloss improvement effect due to the improvement in smoothness has been confirmed. However, when the embedding of the pigment ink into the thermoplastic resin layer is halfway, image-like unevenness occurs in the printed part and the unprinted part, resulting in a difference in gloss. On the contrary, when the pigment ink is sufficiently embedded, the smoothness of the image surface is improved and the difference in gloss between the printed portion and the unprinted portion is eliminated. However, due to the increased smoothness, surface glare may occur due to a decrease in depth or excessive gloss.
[0008]
The image quality may depend on individual preferences, but depending on the purpose of use, glossiness required for high-quality prints and other characteristics may be required.
[0009]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to improve the glare due to surface gloss when ink jet recording is performed using pigment ink, and to create a high-quality feeling that does not cause a gloss difference on the image and suppresses the bronze phenomenon. It is an object of the present invention to provide an image forming method for obtaining a certain inkjet recording material.
[0010]
[Means for Solving the Problems]
The above object of the present invention has been achieved by the following constitution.
[0011]
  1.Using a cooling roll having a regular uneven height on the surface, it is subjected to a mold treatment.The surface side of the support having a center line average roughness (Ra) of 1.0 to 5.0 μm when measured at a measurement length of 2.5 mm and a cut-off value of 0.8 mm defined in JIS-B-0601. After the pigment ink is adhered to the ink jet recording material, which is an ink receiving layer containing thermoplastic resin particles, by an ink jet method,At 50-150 ° CHeating and10-500 N / cm ² At pressureImage forming method for transparentizing ink receiving layer containing thermoplastic resin particles by simultaneously applying pressureBecause, Dry film thickness d after film formation of the ink receiving layer containing the thermoplastic resin particlesIs 3.0 to 6.0 μm, and the dry film thickness dAnd the centerline average roughness (Ra) of the surface of the support is the relationship of the above-mentioned formula 1.
[0012]
2. 2. The inkjet image forming method according to claim 1, wherein the heating and pressurizing are performed using a heat roller.
[0013]
3. 3. The ink jet image forming method according to item 2, wherein the heat roller is a metal roller or a silicon rubber roller.
[0014]
4). 4. The inkjet image forming method according to item 3, wherein the metal roller and the silicon rubber roller have a built-in heat source.
[0015]
5). The inkjet image forming method according to any one of items 2 to 4, wherein a nip width formed by pressing the roller is 1 to 20 mm.
[0018]
As the support according to the present invention, a support conventionally used for an ink jet recording material (hereinafter also simply referred to as a recording material), for example, a paper support such as plain paper, art paper, coated paper and cast coated paper. Further, a plastic support, a paper support coated with polyolefin on both sides, and a composite support obtained by laminating these can be used.
[0019]
In the ink jet recording material according to the present invention, in addition to the ink receiving layer, an ink absorbing layer having an ink solvent absorbing ability (hereinafter referred to as an ink solvent absorbing layer, or simply referred to as an ink absorbing layer) is formed. Preferably, the ink absorbing layer has a void inside the layer, and the void is mainly formed of a hydrophilic binder and inorganic fine particles or organic fine particles.
[0020]
For the purpose of increasing the adhesive strength between the support and the ink absorbing layer, it is preferable to subject the support to corona discharge treatment or subbing treatment prior to application of the ink absorbing layer. Furthermore, the support according to the present invention is not necessarily colorless and may be a colored support.
[0021]
In the ink jet recording material according to the present invention, it is particularly preferable to use a paper support in which both sides of a base paper support are laminated with polyethylene, because a recorded image is close to photographic image quality and a high quality image can be obtained at low cost. preferable. Such a paper support laminated with polyethylene will be described below.
[0022]
The base paper used for the paper support is made from wood pulp as a main raw material and, if necessary, paper making 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 more LBKP, NBSP, LBSP, NDP, and LDP with a short fiber content. However, the ratio of LBSP and / or LDP is preferably 10% by mass or more and 70% by mass or less.
[0023]
As the pulp, chemical pulp (sulfate pulp or sulfite pulp) with less impurities is preferably used, and a pulp whose whiteness is improved by bleaching is also useful. In the base paper, sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc and titanium oxide, paper strength enhancing agents such as starch, polyacrylamide and polyvinyl alcohol, fluorescent whitening agents, polyethylene glycols A water retaining agent such as a dispersant, a softening agent such as a quaternary ammonium, and the like can be appropriately added.
[0024]
The freeness of the pulp used for papermaking is preferably 200 to 500 ml as defined by CSF, and the fiber length after beating is 24% by mass as defined in JIS-P-8207, and 42 mesh residue. 30 to 70% of the sum with the mass% of is preferable. In addition, it is preferable that the mass% of 4 mesh remainder is 20 mass% or less. The basis weight of the base paper is 30 to 250 g / m²In particular, 50 to 200 g / m²Is preferred. The thickness of the base paper is preferably 40 to 250 μm. The base paper can be given a high smoothness by calendering at the paper making stage or after paper making. The base paper density is generally 0.7 to 1.2 (JIS-P-8118). Furthermore, the base paper stiffness is preferably 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 sizing agent 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 defined in JIS-P-8113.
[0025]
The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but some other LLDPE, polypropylene, etc. can also be used. Polyethylene-coated paper can be used as glossy paper. Also, when the polyethylene is melted, extruded and coated on the surface of the base paper, a matte or silky surface that can be obtained with ordinary photographic printing paper by applying a so-called molding process is used. The formed can also be used in the present invention. The amount of polyethylene used on the front and back of the base paper is selected to optimize curling under low and high humidity after the ink solvent absorption layer and back layer are provided. The layer is in the range of 20 to 40 μm, and the back layer side is in the range of 10 to 30 μm.
[0026]
Furthermore, the paper support coated with polyethylene preferably has the following characteristics.
[0027]
1. Tensile strength: strength defined by JIS-P-8113, preferably 2-30 kg in the vertical direction and 1-20 kg in the horizontal direction
2. The tear strength is preferably 10 to 200 g in the vertical direction and 20 to 200 g in the horizontal direction according to a method defined by JIS-P-8116.
3. Compression modulus ≧ 98.1 MPa
4). Opacity: 80% or more, particularly 85 to 98%, when measured by the method defined in JIS-P-8138
5). Whiteness: L defined by JIS-Z-8729^*, A^*, B^*Is L^*= 80-95, a^*= -3 to +5, b^*= −6 to +2 is preferable
6). Clark stiffness: Clark stiffness in the conveyance direction of the recording paper is 50 to 300 cm.²/ 100 support is preferred
7. Moisture in base paper: 4 to 100% by mass is preferable with respect to the middle paper.
[0028]
  In the invention according to claim 1,Using a cooling roll having a regular uneven height on the surface, it is subjected to a mold treatment.The surface side of the support having a center line average roughness (Ra) of 1.0 to 5.0 μm when measured at a measurement length of 2.5 mm and a cut-off value of 0.8 mm defined in JIS-B-0601. After the pigment ink is adhered to the ink jet recording material, which is an ink receiving layer containing thermoplastic resin particles, by an ink jet method,At 50-150 ° CHeating and10-500 N / cm ² At pressureImage forming method for transparentizing ink receiving layer containing thermoplastic resin particles by simultaneously applying pressureBecause, Dry film thickness d after film formation of the ink receiving layer containing the thermoplastic resin particlesIs 3.0 to 6.0 μm, and the dry film thickness dThe center line average roughness (Ra) of the surface of the support is characterized by the relationship of the above formula 1.
[0029]
By defining the relationship between the center line average roughness of the support surface and the dry film thickness of the ink receiving layer containing the thermoplastic resin particles (hereinafter also referred to as the thermoplastic resin layer) within the range of the above formula 1, It is possible to prevent glare without significantly reducing gloss. When the dry film thickness of the thermoplastic resin layer is equal to or less than Ra on the surface of the support, the dry film thickness of the thermoplastic resin layer is too thin and the embedding of the pigment ink into the thermoplastic resin layer becomes insufficient. The printing part appears to be lifted with respect to the printing part, and the smoothness of the printing part becomes insufficient. On the other hand, when the dry film thickness of the thermoplastic resin layer is 4 Ra or more, embedding of the pigment ink in the thermoplastic resin layer is sufficient, and there is no difference in glossiness between the printed portion and the unprinted portion, but the smoothness is excessive. On the contrary, the glaring feeling becomes conspicuous due to the improvement, and the improvement effect of bronze is insufficient and the visual impression is lowered.
[0030]
The center line average roughness (Ra) in the present invention is defined by JIS-B-0601 of JIS surface roughness. That is, the centerline average roughness (Ra) is a portion of the measured length L (2.5 mm in the present invention) extracted from the roughness curve in the direction of the centerline, and the cut-off value is 0.8 mm. When the center line of the portion is represented by the X axis, the direction of the vertical magnification is represented by the Y axis, and the roughness curve is represented by Y = f (X), the value obtained by the following equation is represented by micrometers (μm).
[0031]
[Expression 1]

[0032]
As a measuring method of the center line average roughness (Ra), the humidity was adjusted for 24 hours in a 25 ° C., 65% RH environment under the condition that the measurement samples were not overlapped with each other, and then the measurement was performed in the environment. The non-overlapping conditions shown here include, for example, a method of winding with the edge portion of the support raised, a method of stacking paper between the support and the support, a frame made of cardboard, etc. Is one of the ways to fix. Examples of the measuring apparatus that can be used include a RSTPLUS non-contact three-dimensional micro surface shape measuring system manufactured by WYKO.
[0033]
  As a method of achieving 1.0 to 5.0 μm as the center line average roughness (Ra) of the support surface defined in the present invention.Is a branchWhen the surface of the holder is coated with polyethylene or the like, the surface is cooled using a cooling roll having regular irregularities having different sizes or shapes, and various molding processes are performed on the polyethylene surface to obtain desired surfaces. Obtaining a support having an Ra valueCharacterized by using the method.
[0034]
The surface characteristics obtained by the present invention cannot be obtained only with the matting agent conventionally used in the ink absorbing layer. When a known matting agent is contained in a flat ink absorbing layer, a convex state is usually formed on the surface of the ink absorbing layer. If it is attempted to control the glossiness within a desired range only by the convex shape formed by the matting agent, it becomes necessary to use a matting agent having a significantly larger average particle diameter than the known matting agent, and as a result, The glossiness cannot be controlled within a desired range, and scratches are easily caused, and the touch feeling on the print surface is deteriorated, so that the effect of the present invention cannot be obtained.
[0035]
  In the present invention, when Ra is less than 1 μm, the feeling of glare is increased, and when Ra is more than 5 μm, cracks occur during the production of the recording material. In the present invention, Ra is 1.0 to 5.0 μm, preferably 1.0 to 3.0 μm. Moreover, the dry film thickness d in Formula 1 is3.0-6.0Must be μmCharacterized by.
[0036]
The ink jet recording material of the present invention has the support and the ink receiving layer made of the thermoplastic resin of the present invention on the outermost layer, and the ink solvent component is further separated after the coloring material and the ink solvent component are separated on the surface of the ink receiving layer. It is preferable to have an ink solvent absorption layer (also referred to as a void layer) adjacent to the thermoplastic resin layer to be absorbed.
[0037]
The ink receiving layer according to the present invention is mainly composed of thermoplastic fine particles which are melted and formed into a film by simultaneously performing heating and pressing after image recording with a pigment ink.
[0038]
Examples of the thermoplastic fine particles in the present invention include polycarbonate, polyacrylonitrile, polystyrene, polyacrylic acid, polymethacrylic acid, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyester, polyamide, polyether and their co-polymers. Coalescence is mentioned. Points to consider when selecting a thermoplastic resin include ink acceptability, glossiness after fixing by heating and pressing, and image fastness. Regarding the ink receptivity, when the thermoplastic fine particles are small, the separation of the pigment particles and the ink solvent in the pigment ink is delayed, which causes a substantial decrease in the absorption rate. Moreover, when too large, when coating on a support body, it is unpreferable from the point of the adhesiveness with the adjacent solvent absorption layer, and the film | membrane intensity | strength after coating drying. For this reason, the preferable thermoplastic fine particle diameter is in the range of 0.05 to 10 μm, more preferably 0.1 to 5 μm.
[0039]
Further, as a criterion for selection of the thermoplastic fine particles, there is a glass transition point Tg. When Tg is extremely low, for example, the coating and drying temperature at the time of recording material production is already higher than Tg, and voids due to thermoplastic fine particles for allowing the ink solvent to pass through disappear. On the other hand, when Tg is extremely high, a fixing operation at a high temperature is required for melt film formation after ink jet recording with a pigment ink, and the load on the apparatus and the thermal stability of the support are problematic. The preferable Tg of the thermoplastic fine particles is 50 to 150 ° C.
[0040]
Further, after image formation, the recorded image needs to suppress image quality deterioration due to its storage over time as much as possible. When pigment ink is used, there is no need to worry about density reduction or discoloration in a relatively short period of time as with dye ink, but it is necessary to select thermoplastic fine particles from the viewpoint of suppressing discoloration of unprinted areas as much as possible. There is.
[0041]
The solvent absorption layer of the pigment ink adjacent to the outermost thermoplastic resin layer according to the present invention preferably has voids, which are formed by incorporating various inorganic solid fine particles in the film. . 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, 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. A white inorganic pigment or the like is used. 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-type ink absorbing layer with an electron microscope, obtaining the particle diameter of 100 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 the projected area. From the viewpoints of forming a high-density image, recording a clear image, and producing at low cost, the fine particle silica, colloidal silica and alumina or alumina hydrate synthesized by the vapor phase method as solid fine particles It is preferable to use solid fine particles selected from. Alumina or alumina hydrate may be crystalline or amorphous, and any shape such as irregular particles, spherical particles, and acicular particles can be used. At present, fine particle silica synthesized by such a gas phase method is commercially available, and commercially available fine particle silica includes various types of Aerosil manufactured by Nippon Aerosil Co., Ltd. In order to obtain the effect of the present invention, the particle size of the inorganic fine particles is not particularly limited, but is preferably 100 nm or less, and the most suitable particle size for forming the void portion varies depending on the compound. For example, in the case of the above-mentioned vapor phase method silica, the average particle size (particle size in the dispersion state before coating) of the inorganic fine particles dispersed in the primary particle state is most preferably 4 to 20 nm. Can be used.
[0042]
In addition to using the above-mentioned inorganic fine particles as the ink solvent absorption layer, various hydrophilic resins and silica described in, for example, JP-A Nos. 59-148583, 55-51583, 58-72495, etc. It is also possible to use an ink-receiving layer comprising the above blended solution, an alkylene oxide-containing urethane resin emulsion described in JP-A Nos. 9-150574 and 10-181189, or a urethane resin emulsion containing polycarbonate.
[0043]
In the thermoplastic resin layer and the ink solvent absorption layer of the recording material according to the present invention, the total amount of voids (void volume) is 1 m of the recording material.²It is preferably 20 ml or more per unit. The void volume is 20ml / m²If the amount of ink is less, the ink absorbency is good when the amount of ink at the time of printing is small, but if the amount of ink increases, the ink is not completely absorbed, causing problems such as deterioration in image quality and delay in drying. Prone to occur. The upper limit of the void capacity is not particularly limited, but it is necessary to make the film thickness of the void-type ink absorbing layer approximately 50 μm or less in order not to deteriorate the physical properties of the film such as cracks. Capacity 40ml / m²It is difficult to do this.
[0044]
In the present invention, the void volume is J.P. TAPPI paper pulp test method no. The liquid transfer amount (ml / m) at an absorption time of 2 seconds when measured by the method described in the liquid absorbency test method (Bristow method) of 51-87 paper and paperboard²). In the above measurement method, pure water (ion-exchanged water) is used for the measurement. However, in order to easily determine the measurement area, a water-soluble dye of less than 2% may be contained.
[0045]
A method of applying various constituent layers appropriately provided as necessary, such as a thermoplastic resin layer, an ink solvent absorption layer or a void layer, and an undercoat layer, which are ink receiving layers of the recording material of the present invention, to a support is known. The method can be selected as appropriate. A preferred method is obtained by coating a coating liquid constituting each layer on a support and drying. In this case, two or more layers can be applied at the same time. In particular, all the constituent layers need only be applied once, and simultaneous application is preferred.
[0046]
As the coating method, a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or an extrusion coating method using a hopper described in US Pat. No. 2,681,294 is preferably used. . Further, when applying the ink jet recording material according to the present invention, a thickener may be used in order to improve applicability.
[0047]
The heat roller of the invention according to claim 3 is characterized in that it is constituted by a metal roller or a silicon rubber roller. Of these, the metal roller may be made of a common material such as iron or aluminum, and is coated with tetrafluoroethylene, polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer or the like for the purpose of enhancing thermal durability. Alternatively, it may be mirror-finished to enhance the smoothness after fixing.
[0048]
  The present invention is characterized by heating at 50 to 150 ° C. during heating and pressurization.Claim4In such an invention, the roller has a heat source built therein, and the heat source has a linear heater and heats the surface temperature of the roller to 50 to 150 ° C.preferable. In the heat roller according to the present invention, pressure is applied between the upper and lower rollers to deform the rollers and form a so-called nip. The invention according to claim 5 is characterized in that the nip width is 1 to 20 mm, and preferably 1.5 to 7 mm. When a pair of rollers is used, it is sufficient that at least one of the rollers has a heat source.
[0049]
The pressure according to the present invention requires 20 to 500 N per square centimeter, but if the pressure is lower than this, the pigment particles are not sufficiently pressed into the thermoplastic resin layer by heating and pressurization, and if the pressure is too high, the pigment particles are not pressed. Although it is sufficient, the smoothness and glossiness are too high, resulting in a glaring image.
[0050]
In the pigment ink of the present invention, a surfactant is preferably contained in order to improve the dispersion stability of the pigment. Surfactants preferably used in the ink of the present invention include anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers. Nonionic surfactants such as acetylene glycols and polyoxyethylene / polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. In particular, an anionic surfactant and a nonionic surfactant can be preferably used.
[0051]
As the pigment that can be used in the present invention, conventionally known organic and inorganic pigments can be used. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc. Examples include cyclic pigments, dye lakes such as basic dye lakes, and acid dye lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments, and inorganic pigments such as carbon black.
[0052]
Specific organic pigments are exemplified below.
Examples of pigments for magenta or red 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. And CI Pigment Red 222.
[0053]
Examples of the orange or yellow pigment 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. And CI Pigment Yellow 138.
[0054]
Examples of pigments for green or cyan 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. And CI Pigment Green 7.
[0055]
The pigment ink used in the present invention may contain a pigment dispersant as necessary. Examples of pigment dispersants that can be used include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, sulfosuccinates, naphthalene sulfonates, alkyl phosphates, and polyoxyalkylene alkyl ether phosphates. , Polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, amine oxide and other activators, or styrene, styrene derivatives, vinyl naphthalene derivatives, acrylic acid, acrylic acid Block copolymer comprising at least two monomers selected from derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, fumaric acid derivatives, and random copolymers It is possible to increase the salt.
[0056]
As a method for dispersing the pigment, for example, various types 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.
[0057]
For the purpose of removing the coarse particles of the pigment dispersion of the present invention, it is preferable to use a centrifugal separator or a filter.
[0058]
The average particle size of the pigment dispersion used in the ink of the present invention is preferably 10 nm to 200 nm, more preferably 10 nm to 100 nm, and still more preferably 10 nm to 50 nm. When the average particle diameter of the pigment dispersion exceeds 100 nm, the glossiness of the image recorded on the glossy type recording material is deteriorated. In addition, when the average particle diameter of the pigment dispersion is less than 10 nm, the stability of the pigment dispersion tends to deteriorate, and the storage stability of the ink tends to deteriorate.
[0059]
The particle size of the pigment dispersion can be determined by a commercially available particle size measuring device using a light scattering method, an electrophoresis method, a laser Doppler method or the like. It is also possible to obtain a particle image with a transmission electron microscope on at least 100 particles and perform statistical processing on the image using image analysis software such as Image-Pro (manufactured by Media Cybernetics). Is possible.
[0060]
The ink in the present invention may contain latex. The latex in the present invention refers to polymer particles dispersed in a medium. Examples of the polymer include styrene-butadiene copolymer, polystyrene, acrylonitrile-butadiene copolymer, acrylic ester copolymer, polyurethane, silicon-acrylic copolymer, and acrylic-modified fluororesin. However, acrylic acid esters, polyurethanes and silicon-acrylic copolymers are preferred.
[0061]
In the production of latex, a low molecular weight surfactant is generally used as an emulsifier, but a high molecular weight surfactant (for example, a type in which a solubilizing group is graft-bonded to a polymer or a solubilizing group) is used. A block polymer type in which a portion having an insoluble portion and an insoluble portion are connected) can be used as an emulsifier. There are also latexes that are dispersed without the use of an emulsifier by bonding the solubilizing groups directly to the central polymer of the latex. Latex using a high molecular weight surfactant as an emulsifier and latex not using an emulsifier are called soap-free latex. The latex used in the present invention is not limited to the type and form of the emulsifier, but it is more preferable to use a soap-free latex having excellent ink storage stability.
[0062]
Recently, in addition to latex having a uniform central polymer, there are also core / shell type latexes having different compositions at the center and outer edge of polymer particles. This type of latex can also be preferably used.
[0063]
The average particle size of the latex in the present invention is preferably 150 nm or less, and more preferably 50 nm or less.
[0064]
The average particle diameter of latex can be easily measured using a commercially available measuring apparatus using a light scattering method or a laser Doppler method.
[0065]
In the present invention, the solid content addition amount of the latex is preferably 0.1% by mass or more and 10% by mass or less, and particularly preferably 0.3% by mass or more and 5% by mass or less with respect to the total mass of the ink. If the addition amount is less than 0.1% by mass, it is difficult to exert a sufficient effect on water resistance. If the addition amount exceeds 10% by mass, the ink viscosity increases and the pigment dispersed particle size tends to increase with time. There are many problems in that respect.
[0066]
In the present invention, an electrical conductivity regulator can be used, and examples thereof include inorganic salts such as potassium chloride, ammonium chloride, sodium sulfate, sodium nitrate, and sodium chloride, and aqueous amines such as triethanolamine.
[0067]
In the ink of the present invention and the constituent layers provided as necessary, the viscosity is further adjusted according to the purpose of improving ejection stability, compatibility with print head and ink cartridge, storage stability, image storage stability, and other various performances. Agents, specific resistance adjusting agents, film forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, rust inhibitors, preservatives, etc. can be added, for example, polystyrene, polyacrylates, polymethacrylic acid Esters, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or copolymers thereof, organic latex fine particles such as urea resin or melamine resin, liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicon Oil droplets such as oil, various surfactants of cation or nonion, JP-A-57-74193, 57-87988 and 62-261476, UV absorbers described in JP-A-57-74192, 57-87989, 60-72785, JP-A-61-146591, JP-A-1-95091, JP-A-3-13376, and the like, anti-fading agents described in JP-A-59-42993, JP-A-59-52689, JP-A-62-2. PH of optical brighteners, sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, etc. described in Japanese Patent Nos. 280069, 61-242871, and JP-A-4-219266 Various known additives such as a regulator, an antifoaming agent, an antiseptic, a thickener, an antistatic agent, and a matting agent may be contained.
[0068]
The inkjet head used in the inkjet recording method of the present invention may be an on-demand system or a continuous system. As the discharge method, an electro-mechanical conversion method (for example, single cavity type, double cavity type, bender type, piston type, shear mode type, shared wall type, etc.), electro-thermal conversion method (for example, thermal ink jet) Specific examples include a mold, a bubble jet type, etc., an electrostatic attraction method (for example, an electric field control type, a slit jet type, etc.) and a discharge method (for example, a spark jet type). A discharge method may be used.
[0069]
【Example】
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these embodiments. In addition, unless otherwise indicated, the% display in an Example represents the mass%.
[0070]
Example 1
<Production of support>
Moisture content is 6.5% and basis weight is 170g / m²A low-density polyethylene having a density of 0.92 was applied to the back side of the photographic base paper with a thickness of 30 μm by extrusion coating. Subsequently, a low-density polyethylene containing 5.5% of anatase-type titanium oxide on the surface side and having a density of 0.92 was applied by a melt extrusion coating method to a thickness of 35 μm to prepare a support coated on both sides with polyethylene. . Immediately after the melt extrusion coating, the polyethylene surface was subjected to various molding processes while being cooled using a cooling roll having various regular uneven heights on the surface. The difference in the typing was performed by adjusting the density and the height of the unevenness. Corona discharge is performed on the surface, and the gelatin subbing layer is 0.3 g / m²It applied so that it might become. The center line average roughness of each surface of the various types of imprinted supports 1 to 6 produced as described above was measured by the method described below, and the obtained results are shown in Table 1 described later. .
[0071]
(Measurement of centerline average roughness of support surface)
The centerline surface roughness of each of the prepared support surfaces was measured by the following method. The center line average roughness Ra (μm) was measured using a non-contact three-dimensional surface analyzer (RST / PLUS manufactured by WYKO). Ra was defined according to JIS surface roughness (B0601). For each sample of 30 cm × 30 cm, the sample was divided into 100 on the grid at intervals of 3 cm, the center of each square area was measured, and the average value and standard deviation were obtained from 100 measurements. The centerline average roughness (Ra) is determined by extracting a portion with a measured length of 2.5 mm in the direction of the centerline from the obtained roughness curve and setting the cut-off value to 0.8 mm. When the X axis, the direction of the vertical magnification are represented by the Y axis, and the roughness curve is represented by Y = f (X), the value obtained by the above equation (Equation 1) is represented by micrometers (μm).
[0072]
<< Preparation of Titanium Oxide Dispersion-1 >>
20 kg of titanium oxide (Ishihara Sangyo: W-10) with an average particle size of 0.25 μm, 150 g of sodium tripolyphosphate with pH 7.5, 500 g of polyvinyl alcohol (Kuraray Co., Ltd .: PVA235, average polymerization degree 3500), cationic After adding the polymer (P-1) to 90 liters of an aqueous solution containing 150 g of the polymer (P-1) and 10 g of the defoaming agent SN381 manufactured by Sannobuco Co., Ltd. A uniform titanium oxide dispersion-1 was obtained.
[0073]
<< Preparation of Silica Dispersion-1 >>
125 kg of vapor phase method silica (Nippon Aerosil Kogyo Co., Ltd .: A300) having an average primary particle size of 0.007 μm was mixed with nitric acid using a jet stream inductor mixer TDS manufactured by Mitamura Riken Kogyo Co., Ltd. and pH 2.5. After suction and dispersion in 620 liters of pure water adjusted to room temperature at room temperature, the whole amount was finished to 694 liters with pure water. When this dispersion was diluted and silica particles were photographed with an electron micrograph, it was confirmed that most of the particles had a particle size of 0.01 μm or less and were dispersed up to the primary particles. Most of the particles mentioned here are particles occupying 85 to 90%.
[0074]
<< Preparation of silica dispersion-2 >>
In a temperature range of 25 to 30 ° C. in an aqueous solution of 18 liters of pH 2.3 containing 1.41 kg of cationic polymer (P-2) and 4.2 liters of ethanol, 69. Add 4 liters with stirring over 20 minutes, then add 7.0 liters of aqueous solution with pH 7.3 containing 260 g of boric acid and 230 g of borax over 10 minutes, then add 1 g of antifoam SN381 did. This mixed solution was dispersed twice with a high pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd. at a pressure of 24.5 MPa, and the whole amount was finished to 97 liters with pure water, and a substantially transparent silica dispersion having an average particle size of 0.007 μm— 2 was prepared.
[0075]
[Chemical 1]

[0076]
<< Preparation and Application of Coating Solution for Ink Solvent Absorption Layer >>
The coating liquids for the first layer, the second layer, and the third layer were prepared and applied by the following procedure to form an ink solvent absorption layer.
[0077]
<Coating liquid for first layer>
The following additives were sequentially mixed with 600 ml of silica dispersion-1 while stirring at 40 ° C.
[0078]
  Polyvinyl alcohol (Kuraray Industries, Ltd .: PVA235
    194.6 ml of 7% aqueous solution with an average degree of polymerization of 3500)
  Titanium oxide dispersion-1 33ml
  Latex emulsion, AE-803:Showa Polymer18ml
  Finish the whole volume to 1000ml with pure water. The coating solution pH was 4.4.
[0079]
<Second layer coating solution>
The following additives were sequentially mixed with 650 ml of silica dispersion-2 while stirring at 40 ° C.
[0080]
Polyvinyl alcohol (Kuraray Industries, Ltd .: PVA235
201.6 ml of 7% solution of average degree of polymerization: 3500)
Finish the whole volume to 1000ml with pure water. The coating solution pH was 4.4.
[0081]
<3rd layer coating solution>
The following additives were sequentially mixed with 650 ml of silica dispersion-2 while stirring at 40 ° C.
[0082]
Polyvinyl alcohol (Kuraray Industries, Ltd .: PVA235
201.6 ml of 7% aqueous solution with an average degree of polymerization of 3500)
Silicon dispersion (Toray Dow Corning Silicone Co., Ltd .:
BY-22-839) 15ml
Saponin 50% aqueous solution 4ml
Finish the whole volume to 1000ml with pure water. The pH of the coating solution was 4.5.
[0083]
Each coating solution prepared as described above was filtered with the following filter.
First layer and second layer: two-stage filtration with Toyo Filter Paper Co., Ltd. TCP10
Third layer: 2-stage filtration with Toyo Filter Paper Co., Ltd. TCP30
<Application of first layer to third layer>
Subsequently, each layer was apply | coated to each said support body so that it might become a 1st layer (50 micrometers), a 2nd layer (100 micrometers), and a 3rd layer (50 micrometers) in order. The values in the parentheses indicate wet film thicknesses, and the first to third layers were simultaneously applied.
[0084]
Each coating solution was applied with a three-layer slide hopper at 40 ° C., cooled for 20 seconds in a cooling zone maintained at 0 ° C. immediately after application, and then with 25 ° C. wind (relative humidity 15%). 60 seconds, air for 45 seconds at 45 ° C (relative humidity 25%), 60 seconds for wind at 50 ° C (25% relative humidity), 20-25 ° C, relative humidity 40-60 ° C The sample was wound up for 2 minutes to obtain the recording materials 1 to 6 having only the ink solvent absorption layer.
[0085]
<< Preparation and application of coating solution for thermoplastic resin layer >>
Next, a coating solution for a thermoplastic resin layer was prepared according to the following formulation.
[0086]
AT-2000 (styrene-acrylic acid copolymer latex Tg: 80 ° C.,
MFT: 85 ° C (made by Showa Polymer Co., Ltd.) 50%
AS-7180 (acrylic copolymer Na salt aqueous solution
(Toagosei Chemical Industry Co., Ltd.) 3%
47% of water
On the recording materials 1 to 6 having only the solvent absorbing layer, the coating solution for the thermoplastic resin layer is applied with a slide hopper so as to have a dry film thickness as shown in Table 1, and under the same conditions as above. It dried and produced the recording materials 101-114.
[0087]
<Recording images on recording materials>
(Preparation of yellow pigment dispersion)
C. I. Pigment Yellow 128 150g
Styrene-acrylic-methyl methacrylate copolymer (molecular weight 10,000,
Acid value 160) 70 g
Ethylene glycol 100g
Glycerin 80g
200g of ion exchange water
Were dispersed using a horizontal bead mill (System Zetamini manufactured by Ashizawa Co., Ltd.) filled with 0.3 mm zirconia beads at a volume ratio of 60% to obtain a yellow pigment dispersion. The average particle diameter of the obtained yellow pigment dispersion was 125 nm. The average particle size of the pigment ink dispersion was measured using a Zetasizer 1000 (manufactured by Malvern).
[0088]
(Preparation of magenta pigment dispersion)
C. I. Pigment Red 122 100g
DEMAL C 63g
Glycerin 100g
Ion exchange water 130g
Were dispersed using a horizontal bead mill (System Zetamini manufactured by Ashizawa Co., Ltd.) filled with 0.3 mm zirconia beads at a volume ratio of 60% to obtain a magenta pigment dispersion. The average particle size of the obtained magenta pigment dispersion was 65 nm.
[0089]
(Preparation of cyan pigment dispersion)
C. I. Pigment Blue 15: 3 100g
DEMAL C 63g
Diethylene glycol 100g
125g of ion exchange water
And dispersed using a horizontal bead mill (system zeta mini manufactured by Ashizawa Co., Ltd.) filled with 0.3 mm zirconia beads at a volume ratio of 60%, and then centrifuged at 20,000 rpm for 30 minutes. A pigment dispersion was obtained. The average particle diameter of the obtained cyan pigment dispersion was 55 nm.
[0090]
(Preparation of black pigment dispersion)
Hostfine Black T (manufactured by Clariant,
(Average particle size 50 nm) 167 g
Latex 4 (Superflex 460, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 78.9 g
200g ethylene glycol
120 g of triethylene glycol monomethyl ether
Orphine GXL (Nisshin Chemical Co., Ltd.) 4g
Proxel GXL (Zeneca) 2g
The above was finished to 1000 g with ion-exchanged water and passed through a 1 μm Millipore filter twice to prepare a pigment ink.
[0091]
<< Recording and evaluation of images on recording materials >>
For the recording materials 101 to 114 produced above, a nozzle particle size of 20 μm, a driving frequency of 12 kHz, a number of nozzles of 128 per color, and a nozzle density of the same color of 180 dpi (dpi in the present invention is the number of dots per 2.54 cm). A uniform solid image pattern of each color for each color of yellow, magenta, cyan, and black using the above-described pigment ink using an on-demand type inkjet having a maximum recording density of 720 × 720 dpi. did.
[0092]
Subsequently, with respect to the samples to which the above-described image pattern is applied to the recording materials 101 to 109, both a cylindrical iron cylinder (upper roller) with a diameter of 30 mmφ and a silicon rubber roller (lower roller with a diameter of 30 mmφ) are both tetrafluoro. Using a fixing device coated with an ethylene-perfluoroalkyl ether copolymer and having a heater built in an iron cylinder, a linear pressure of 100 N / cm²The nip width was 4.3 mm, the linear velocity was 10 mm / s, and the heating and pressure treatment were performed under the conditions of a heating temperature of 100 ° C.
[0093]
The recording material 110 was only subjected to a heat treatment at 100 ° C. for 10 minutes after image recording without using a fixing device.
[0094]
The recording material 111 was subjected to heat treatment at 100 ° C. for 10 minutes after image recording, and then subjected to pressure treatment using the fixing device.
[0095]
The recording material 112 was heated and pressed at the same time using the above-described fixing device. However, the fixing was performed by combining two iron rollers coated with a tetrafluoroalkyl ether copolymer for fixing, so that there is substantially no nip width. The fixing process was performed at
[0096]
The recording material 113 was subjected to the same fixing process as the recording materials 101 to 109 after image recording, but the fixing temperature was set to 170 ° C.
[0097]
The recording material 114 was subjected to the same fixing treatment as that of the recording materials 101 to 109 after image recording, but the linear pressure during fixing was 5 N / cm.²It was.
[0098]
For each recorded image produced by the above processing, the gloss difference between the printed part and the unprinted part and the bronze of the printed part were visually evaluated according to the criteria shown below, and the obtained results are also shown in Table 1.
[0099]
<Gloss difference between printed and unprinted areas>
A: Little difference in gloss is felt
○: Some gloss difference is recognized, but there is no practical problem
Δ: There is a gloss difference that has a practical problem.
×: Remarkably large gloss difference
<bronze>
A: Bronze is hardly felt
○: Some bronze is recognized, but there is no problem in practical use
Δ: Bronze with practical problems
×: Significant bronze is observed
[0100]
[Table 1]

[0101]
As is clear from the results in Table 1, the sample 103 and the samples 106 to 109 have a large gloss difference between the printed portion and the unprinted portion, bronzes are observed, and only prints that are practically problematic are obtained. Recording material 101 of the present invention (d / Ra = 2.4), recording material 102 (d / Ra = 2.78), recording material 104 (d / Ra = 1.08) and recording material 105 (d / Ra = In 2.78), there is no gloss difference between the printed part and the non-printed part, and it can be seen that a bronze improvement effect is great and a high-quality image is obtained.
[0102]
Further, the recording material production conditions are the same as those of the recording material 101, and the recording material 110 is heated only after printing. The recording material production conditions are the same as the recording material 104, and the recording material 111 is pressurized after heating. In either case, the gloss difference between the printed portion and the unprinted portion could not be eliminated, and bronzing was observed, and the effectiveness of the effect of simultaneously performing heating and pressurization according to the present invention could be confirmed.
[0103]
In addition, the recording material 112 is fixed by combining a metal roller after image recording under substantially no nip width, the recording material 113 at a fixing temperature of 170 ° C., and the fixing pressure after image recording is 1 The recording material 114 having 5N per square centimeter has a slightly high gloss on the printed portion and bronzing is not completely eliminated, but is at a level that does not cause a problem in practice.
[0104]
【The invention's effect】
As demonstrated in the examples, the image forming method according to the present invention has a high-class feeling in which bronzing is suppressed without causing a significant difference in gloss between the printed portion and the unprinted portion when ink-jet recording is performed using pigment ink. Ink jet recording images with a high density were obtained.

Claims (5)

Center line when measured with 2.5mm measurement length and 0.8mm cut-off value as defined in JIS-B-0601, by using a cooling roll with regular irregularities on the surface. A pigment ink is adhered to an ink jet recording material in which the outermost layer on the surface side of the support having an average roughness (Ra) of 1.0 to 5.0 μm is an ink receiving layer containing thermoplastic resin particles by an ink jet method. after, by performing pressurization at a pressure of heating and 10~500N / cm ² at 50 to 150 ° C. at the same time, an image forming method of clearing the ink-receiving layer containing the thermoplastic resin particles The dried film thickness d after forming the ink receiving layer containing the thermoplastic resin particles is 3.0 to 6.0 μm, and the dried film thickness d and the center line average roughness (Ra) of the support surface are: It is the relationship of the following formula 1. An ink jet image forming method.
Formula 1
Ra <d <4Ra   The inkjet image forming method according to claim 1, wherein the heating and pressing are performed using a heat roller.   The inkjet image forming method according to claim 2, wherein the heat roller is a metal roller or a silicon rubber roller.   The inkjet image forming method according to claim 3, wherein the metal roller and the silicon rubber roller have a built-in heat source.   The inkjet image forming method according to any one of claims 2 to 4, wherein a nip width formed by pressing the roller is 1 to 20 mm.