JP2004009361A - Inkjet recording sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording sheet exhibiting excellent glossiness before printing in which a flaw on the surface of a not yet printed sheet is inconspicuous after printing and a high image quality ink jet image exhibiting excellent blur resistance is obtained with high density. <P>SOLUTION: In the ink jet printing sheet having at least one ink absorption layer on a support, a porous ink absorption layer consisting of a hydrophilic binder, a cationic compound and inorganic fine particles where the mean grain size of primary particles is not larger than 50 nm is provided on at least one surface of the support. The 60° mirror surface glossiness regulated by JIS Z8741 is set at 30% or above on the surface of the porous ink absorption layer and the C value regulated by JIS K7105 is set in the range of 65-85%. <P>COPYRIGHT: (C)2004,JPO

Description

【００７９】
カチオン性基を有しない共重合可能な繰り返し単位としては、例えば、エチレン、スチレン、ブタジエン、メチルメタクリレート、エチルメタクリレート、プロピルメタクリレート、ブチルメタクリレート、オクチルメタクリレート、メチルアクリレート、エチルアクリレート、プロピルアクリレート、ブチルアクリレート、オクチルアクリレート、ヒドロキシルエチルメタクリレート、アクリルアミド、酢酸ビニル、ビニルメチルエーテル、塩化ビニル、４−ビニルピリジン、Ｎ−ビニルピロリドン、Ｎ−ビニルイミダゾール、アクリルニトリルなどを挙げることができる。
【００８０】
本発明に係るカチオン性ポリマーが、前記一般式（１）で表される繰り返し単位を有する場合、前記一般式（１）で表される繰り返し単位は、好ましくは２０モル％以上、特に好ましくは４０〜１００モル％である。
【００８１】
本発明に係る一般式（１）で表される繰り返し単位を有するカチオン性ポリマーの具体例を以下に示すが、本発明はこれらに限定されるものではない。
【００８２】
【化３】

【００８３】
【化４】

【００８４】
【化５】

【００８５】
カチオン性ポリマーの重量平均分子量としては、２０００〜５０万の範囲であることが好ましく、更に好ましくは３０００〜１０万の範囲である。
【００８６】
また、本発明に係るカチオン性ポリマーを塗布液にあらかじめ添加する場合、均一に塗布液に添加するのみならず、無機微粒子とともに複合粒子を形成する形で添加してもよい。無機微粒子とカチオン性ポリマーによって複合粒子を作製する方法としては、無機微粒子にカチオン性ポリマーを混合し吸着被覆させる方法、その被覆粒子を凝集させてより高次の複合粒子を得る方法、さらには混合して得られる粗大粒子を分散機によってより均一な複合粒子にする方法などが挙げられる。
【００８７】
カチオン性ポリマーは、概ね水溶性基を有する為に水溶性を示すが、例えば、共重合成分の組成によっては水に溶解しないことがある。製造の容易性から水溶性であることが好ましいが、水に難溶であっても水混和性有機溶媒を用いて溶解し使用することも可能である。
【００８８】
ここで、水混和性有機溶媒とは、メタノール、エタノール、イソプロパノール、ｎ−プロパノールなどのアルコール類、エチレングリコール、ジエチレングリコール、グリセリンなどのグリコール類、酢酸エチル、酢酸プロピル等のエステル類、アセトン、メチルエチルケトン等のケトン類、Ｎ，Ｎ−ジメチルホルムアミド等のアミド類など、水に対して概ね１０％以上溶解し得る有機溶媒を言う。この場合、有機溶媒の使用量は水の使用量以下であることが好ましい。
【００８９】
カチオン性ポリマーはインクジェット記録用紙１ｍ^２当たり通常０．１〜１０ｇ、好ましくは２〜５ｇの範囲で用いられる。
【００９０】
請求項６に係る発明では、カチオン性化合物の少なくとも１種が、ジルコニウム原子を有する化合物（但し、酸化ジルコニウムを除く）又はアルミニウム原子を有する化合物（但し、酸化アルミニウムを除く）であることが好ましい。
【００９１】
ジルコニウム原子を有する化合物の具体例としては、二フッ化ジルコニウム、三フッ化ジルコニウム、四フッ化ジルコニウム、ヘキサフルオロジルコニウム酸塩（例えば、カリウム塩）、ヘプタフルオロジルコニウム酸塩（例えば、ナトリウム塩、カリウム塩やアンモニウム塩）、オクタフルオロジルコニウム酸塩（例えば、リチウム塩）、フッ化酸化ジルコニウム、二塩化ジルコニウム、三塩化ジルコニウム、四塩化ジルコニウム、ヘキサクロロジルコニウム酸塩（例えば、ナトリウム塩やカリウム塩）、酸塩化ジルコニウム（例えば、塩化ジルコニル）、二臭化ジルコニウム、三臭化ジルコニウム、四臭化ジルコニウム、臭化酸化ジルコニウム、三ヨウ化ジルコニウム、四ヨウ化ジルコニウム、過酸化ジルコニウム、水酸化ジルコニウム、硫化ジルコニウム、硫酸ジルコニウム、ｐ−トルエンスルホン酸ジルコニウム、硫酸ジルコニル、硫酸ジルコニルナトリウム、酸性硫酸ジルコニル三水和物、硫酸ジルコニウムカリウム、セレン酸ジルコニウム、硝酸ジルコニウム、硝酸ジルコニル、リン酸ジルコニウム、炭酸ジルコニル、炭酸ジルコニルアンモニウム、酢酸ジルコニウム、酢酸ジルコニル、酢酸ジルコニルアンモニウム、乳酸ジルコニル、クエン酸ジルコニル、ステアリン酸ジルコニル、リン酸ジルコニウム、リン酸ジルコニル、シュウ酸ジルコニウム、ジルコニウムイソプロピレート、ジルコニウムブチレート、ジルコニウムアセチルアセトネート、アセチルアセトンジルコニウムブチレート、ステアリン酸ジルコニウムブチレート、ジルコニウムアセテート、ビス（アセチルアセトナト）ジクロロジルコニウム、トリス（アセチルアセトナト）クロロジルコニウムなどが挙げられる。
【００９２】
アルミニウム原子を有する化合物の具体例としては、フッ化アルミニウム、ヘキサフルオロアルミン酸（例えば、カリウム塩等）、塩化アルミニウム、塩基性塩化アルミニウム（例えば、ポリ塩化アルミニウム）、テトラクロロアルミン酸塩（例えば、ナトリウム塩等）、臭化アルミニウム、テトラブロモアルミン酸塩（例えば、カリウム塩など）、ヨウ化アルミニウム、アルミン酸塩（例えば、ナトリウム塩、カリウム塩、カルシウム塩等）、塩素酸アルミニウム、過塩素酸アルミニウム、チオシアン酸アルミニウム、硫酸アルミニウム、塩基性硫酸アルミニウム、硫酸アルミニウムカリウム（ミョウバン）、硫酸アンモニウムアルミニウム（アンモニウムミョウバン）、硫酸ナトリウムアルミニウム、燐酸アルミニウム、硝酸アルミニウム、燐酸水素アルミニウム、炭酸アルミニウム、ポリ硫酸珪酸アルミニウム、ギ酸アルミニウム、酢酸アルミニウム、乳酸アルミニウム、蓚酸アルミニウム、アルミニウムイソプロピレート、アルミニウムブチレート、エチルアセテートアルミニウムジイソプロピレート、アルミニウムトリス（アセチルアセトネート）、アルミニウムトリス（エチルアセトアセテート）、アルミニウムモノアセチルアセトネートビス（エチルアセトアセトネート）等を挙げることができる。
【００９３】
本発明に係るジルコニウム原子またはアルミニウム原子を有する化合物（但し酸化ジルコニウムおよび酸化アルミニウムを除く）の中でも、ポリ塩化アルミニウム化合物、ポリ硫酸アルミニウム、ポリ硫酸ケイ酸アルミニウム化合物またはジルコニウム系活性無機ポリマーであることが最も好ましい。
【００９４】
ポリ塩化アルミニウム化合物は、一般式〔Ａｌ_２（ＯＨ）_ｎＣｌ_６−ｎ〕_ｍ、〔Ａｌ（ＯＨ）_３〕_ｎ・ＡｌＣｌ_３で示されるものであり、例えば、〔Ａｌ_６（ＯＨ）_１５〕^３＋、〔Ａｌ_８（ＯＨ）_２０〕^４＋、〔Ａｌ_１３（ＯＨ）_３４〕^５＋などのような塩基性で、かつ高い陽電子を持った多核縮合イオン（高分子性）を有効成分として、安定に含んでいるポリ塩化アルミニウムである。
【００９５】
ポリ塩化アルミニウム化合物の市販品としては、例えば、浅田化学（株）製のポリ水酸化アルミニウム（Ｐａｈｏ）、多木化学（株）製のポリ塩化アルミニウム（ＰＡＣ）、（株）理研グリーン製のピュラケムＷＴが挙げられる。
【００９６】
また、ポリ硫酸アルミニウム化合物は、一般式〔Ａｌ_２（ＯＨ）_ｎ（ＳＯ_４）_{６−ｎ／２}〕_ｍ（ただし、０＜ｎ＜６）で表されるものであり、市販品としては浅田化学（株）製の塩基性硫酸アルミニウム（ＡＨＳ）が挙げられる。
【００９７】
ポリ硫酸ケイ酸アルミニウム化合物の市販品としては、日本軽金属（株）製のＰＡＳＳが挙げられる。
【００９８】
酸塩化ジルコニウム系無機ポリマーの市販品としては、第一希元素化学工業（株）製のジルコゾールＺＣ−２を挙げることができる。
【００９９】
本発明に係るカチオン性化合物は、多孔質性のインク吸収層の塗布液に添加してから塗布乾燥してもよいし、多孔質性のインク吸収層塗布乾燥後の被膜にその水溶液を含浸させて添加してもよい。また、多孔質性のインク吸収層塗布後乾燥前に添加する方法も挙げられる。多孔質性のインク吸収層塗布後乾燥前に添加する方法としては、オーバーコート法、カーテン塗布、スプレー塗布等が考えられる。
【０１００】
本発明に係るカチオン性化合物を多孔質性のインク吸収層を形成する塗布液に添加する場合、水や有機溶媒あるいはこれらの混合溶媒に均一に溶解して添加すること、あるいはサンドミルなどの湿式粉砕法や乳化分散などの方法により微細な粒子に分散して添加することができる。多孔質性のインク吸収層が複数の層から構成される場合には、１層のみ添加してもよく、２層以上の層あるいは全ての層を形成する塗布液に添加することもできる。
【０１０１】
また、多孔質性のインク吸収層を一旦形成した後、オーバーコート方法により添加する場合には均一な溶液に溶解して添加するのが好ましい。さらに、カチオン性化合物は２種以上併用することもできる。
【０１０２】
上記以外に、例えば、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、アニオン、カチオン又は非イオン性の各種界面活性剤、特開昭５９−４２９９３号公報、同５９−５２６８９号公報、同６２−２８００６９号公報、同６１−２４２８７１号公報及び特開平４−２１９２６６号公報等に記載されている蛍光増白剤、消泡剤、ジエチレングリコール等の潤滑剤、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。
【０１０３】
請求項２に係る発明においては、支持体が、非吸水性支持体であることが好ましい。
【０１０４】
本発明のインクジェット記録用紙の支持体としては、吸水性又は非吸水性の支持体を用いることができるが、非吸水性支持体の方が、プリント後にシワの発生が無く、画像に平滑性の差が生ぜずに高品位のプリントが得られるために好ましい。
【０１０５】
吸水性支持体としては、紙支持体が一般的であるが、布あるいは多孔質のフィルム支持体も含まれる。
【０１０６】
また、非吸水性支持体としてはポリエチレンテレフタレート樹脂、ポリエステル系樹脂、ジアセテート系樹脂、トリアセテート系樹脂、アクリル系樹脂、ポリカーボネート系樹脂、ポリ塩化ビニル系樹脂、ポリイミド系樹脂、セロハン、セルロイド等の材料からなるフィルム等、金属やガラス、さらにはポリエチレン樹脂被覆層を有する樹脂被覆紙（いわゆるＲＣペーパー）、ポリエチレンテレフタレートに白色顔料を添加したホワイトペットなどが挙げられる。
【０１０７】
その中でも原紙支持体の両面をポリエチレンでラミネートした紙支持体を用いることが、記録画像が写真画質に近く、しかも低コストで高品質の画像が得られる為に特に好ましい。
【０１０８】
以下、本発明で特に好ましい支持体である紙の両面をポリオレフィン樹脂で被覆した支持体について説明する。
【０１０９】
本発明に係る支持体で用いられる紙は、木材パルプを主原料とし、必要に応じて木材パルプに加えてポリプロピレン等の合成パルプあるいはナイロンやポリエステル等の合成繊維を用いて抄紙される。木材パルプとしてはＬＢＫＰ、ＬＢＳＰ、ＮＢＫＰ、ＮＢＳＰ、ＬＤＰ、ＮＤＰ、ＬＵＫＰ、ＮＵＫＰのいずれも用いることができるが短繊維分の多いＬＢＫＰ、ＮＢＳＰ、ＬＢＳＰ、ＮＤＰ、ＬＤＰをより多く用いることが好ましい。ただし、ＬＢＳＰ及び／またはＬＤＰの比率は１０〜７０％が好ましい。上記パルプは、不純物の少ない化学パルプ（硫酸塩パルプや亜硫酸塩パルプ）が好ましく用いられ、また漂白処理を行って白色度を向上させたパルプも有用である。
【０１１０】
紙中には、例えば、高級脂肪酸、アルキルケテンダイマー等のサイズ剤、炭酸カルシウム、タルク、酸化チタン等の白色顔料、スターチ、ポリアクリルアミド、ポリビニルアルコール等の紙力増強剤、蛍光増白剤、ポリエチレングリコール類等の水分保持剤、分散剤、４級アンモニウム等の柔軟化剤等を適宜添加することができる。
【０１１１】
抄紙に使用するパルプの濾水度は、ＣＳＦの規定で２００〜５００ｍｌが好ましく、また、叩解後の繊維長がＪＩＳ　Ｐ　８２０７に規定される２４メッシュ残分と４２メッシュ残分の和が３０〜７０％が好ましい。なお、４メッシュ残分は２０％以下であることが好ましい。
【０１１２】
紙の坪量は５０〜２５０ｇが好ましく、特に、７０〜２００ｇが好ましい。紙の厚さは５０〜２１０μｍが好ましい。
【０１１３】
紙は、抄紙段階または抄紙後にカレンダー処理して高平滑性を与えることもできる。紙密度は０．７〜１．２ｇ／ｍ^２（ＪＩＳ　Ｐ　８１１８）が一般的である。更に原紙剛度はＪＩＳ　Ｐ　８１４３に規定される条件で２０〜２００ｇが好ましい。
【０１１４】
紙表面には表面サイズ剤を塗布しても良く、表面サイズ剤としては前記原紙中に添加できるのと同様のサイズ剤を使用できる。
【０１１５】
紙のｐＨは、ＪＩＳ　Ｐ　８１１３で規定された熱水抽出法により測定された場合、ｐＨ５〜９であることが好ましい。
【０１１６】
次に、この紙の両面を被覆するポリオレフィン樹脂について説明する。
この目的で用いられるポリオレフィン樹脂としては、ポリエチレン、ポリプロピレン、ポリイソブチレン、ポリエチレンが挙げられるが、プロピレンを主体とする共重合体等のポリオレフィン類が好ましく、ポリエチレンが特に好ましい。
【０１１７】
以下、特に好ましいポリエチレンについて説明する。
紙表面及び裏面を被覆するポリエチレンは、主として低密度のポリエチレン（ＬＤＰＥ）及び／または高密度のポリエチレン（ＨＤＰＥ）であるが、他のＬＬＤＰＥやポリプロピレン等も一部使用することができる。
【０１１８】
特に、塗布層側のポリオレフィン層は、ルチルまたはアナターゼ型の酸化チタンをその中に添加し、不透明度及び白色度を改良したものが好ましい。酸化チタン含有量はポリオレフィンに対して概ね１〜２０％、好ましくは２〜１５％である。
【０１１９】
ポリオレフィン層中には、白地の調整を行うための耐熱性の高い着色顔料や蛍光増白剤を添加することができる。
【０１２０】
着色顔料としては、例えば、群青、紺青、コバルトブルー、フタロシアニンブルー、マンガンブルー、セルリアン、タングステンブルー、モリブデンブルー、アンスラキノンブルー等が挙げられる。
【０１２１】
蛍光増白剤としては、例えば、ジアルキルアミノクマリン、ビスジメチルアミノスチルベン、ビスメチルアミノスチルベン、４−アルコキシ−１，８−ナフタレンジカルボン酸−Ｎ−アルキルイミド、ビスベンズオキサゾリルエチレン、ジアルキルスチルベン等が挙げられる。
【０１２２】
紙の表裏のポリエチレンの使用量は、インク吸収層の膜厚やバック層を設けた後で低湿及び高湿化でのカールを最適化するように選択されるが、一般にはポリエチレン層の厚さはインク吸収層側で１５〜５０μｍ、バック層側で１０〜４０μｍの範囲である。表裏のポリエチレンの比率はインク受容層の種類や厚さ、中紙の厚み等により変化するカールを調整する様に設定されるのが好ましく、通常は表／裏のポリエチレンの比率は、厚みで概ね３／１〜１／３である。
【０１２３】
更に、上記ポリエチレンで被覆紙支持体は、以下（１）〜（７）の特性を有していることが好ましい。
【０１２４】
（１）引っ張り強さ：ＪＩＳ　Ｐ　８１１３で規定される強度で縦方向が１９．６〜２９４Ｎ、横方向が９．８〜１９６Ｎであることが好ましい。
【０１２５】
（２）引き裂き強度：ＪＩＳ　Ｐ　８１１６で規定される強度で縦方向が０．２０〜２．９４Ｎ、横方向が０．０９８〜２．４５Ｎが好ましい。
【０１２６】
（３）圧縮弾性率：９．８ｋＮ／ｃｍ^２が好ましい。
（４）不透明度：ＪＩＳ　Ｐ　８１３８に規定された方法で測定したときに８０％以上、特に８５〜９８％が好ましい。
【０１２７】
（５）白さ：ＪＩＳ　Ｚ　８７２７で規定されるＬ^＊、ａ^＊、ｂ^＊が、Ｌ^＊＝８０〜９６、ａ^＊＝−３〜＋５、ｂ^＊＝−７〜＋２であることが好ましい。
【０１２８】
（６）クラーク剛直度：記録用紙の搬送方向のクラーク剛直度が５０〜３００ｃｍ^３／１００である支持体が好ましい。
【０１２９】
（７）原紙中の水分は、中紙に対して４〜１０％が好ましい。
（８）インク受容層を設ける光沢度（７５度鏡面光沢度）は１０〜９０％が好ましい。
【０１３０】
（その他のインクジェット記録用紙の構成因子）
本発明のインクジェット記録用紙において、多孔質インク吸収層及び下引き層など必要に応じて適宜設けられる各種の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できる。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、特に全ての親水性バインダー層を１回の塗布で済ます同時塗布が好ましい。
【０１３１】
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。
【０１３２】
本発明のインクジェット記録用紙の記録面の膜面ｐＨは、３．０〜７．５が好ましい。膜面ｐＨが３．０以上であれば、インクジェットで記録した際に染料が析出して金属状に光沢が変化するいわゆるブロンジングを防止でき、また、膜面ｐＨが７．５以下であれば、十分な滲み耐性を発揮することができる。
【０１３３】
本発明のインクジェット記録用紙の記録面の膜面ｐＨの測定は、Ｊ．ＴＡＰＰＩ紙パルプ試験方法Ｎｏ．４９に記載の方法に従って、蒸留水を用い、３０秒後に測定する方法で求めることができる。
【０１３４】
本発明において、記録面の膜面ｐＨは、記録面を形成する塗工液のｐＨを調整することにより所定の範囲にすることができる。また、記録面を形成した後、適当なｐＨ調整剤をオーバーコートすることにより所定の範囲にすることもできる。ｐＨ調整剤としては適当な酸やアルカリの水溶液を用いることもでき、この場合、使用する酸やアルカリの種類、濃度は、調整するｐＨの幅によって適宜選択することができる。
【０１３５】
なお、本発明のインクジェット記録用紙は、特に水溶性染料インクを用いたインクジェット記録において特に効果が大きく好ましいが、顔料インクを用いたインクジェット記録でも使用することが出来る。
【０１３６】
本発明のインクジェット記録用紙を用いて画像記録する際には、水性インクを用いた記録方法が好ましく用いられる。
【０１３７】
上記水性インクとは、下記着色剤及び溶媒、その他の添加剤を有する記録液体である。着色剤としては、インクジェットで公知の直接染料、酸性染料、塩基性染料、反応性染料あるいは食品用色素等の水溶性染料あるいは水分散性顔料が使用できる。
【０１３８】
水性インクの溶媒としては、水及び水溶性の各種有機溶剤、例えば、メチルアルコール、イソプロピルアルコール、ブチルアルコール、ｔｅｒｔ−ブチルアルコール、イソブチルアルコール等のアルコール類；ジメチルホルムアミド、ジメチルアセトアミド等のアミド類；アセトン、ジアセトンアルコール等のケトンまたはケトンアルコール類；テトラヒドロフラン、ジオキサン等のエーテル類；ポリエチレングリコール、ポリプロピレングリコール等のポリアルキレングリコール類；エチレングリコール、プロピレングリコール、ブチレングリコール、トリエチレングリコール、１，２，６−ヘキサントリオール、チオジグリコール、ヘキシレングリコール、ジエチレングリコール、グリセリン、トリエタノールアミン等の多価アルコール類；エチレングリコールメチルエーテル、ジエチレングリコールメチル（又はエチル）エーテル、トリエチレングリコールモノブチルエーテル等の多価アルコールの低級アルキルエーテル類等が挙げられる。中でも、ジエチレングリコール、トリエタノールアミンやグリセリン等の多価アルコール類、トリエチレングリコールモノブチルエーテルの多価アルコールの低級アルキルエーテル等は好ましいものである。
【０１３９】
その他の水性インクの添加剤としては、例えば、ｐＨ調節剤、金属封鎖剤、防カビ剤、粘度調整剤、表面張力調整剤、湿潤剤、界面活性剤及び防錆剤、等が挙げられる。
【０１４０】
水性インク液は、記録用紙に対する濡れ性を良好にするために、２０℃において、通常、０．０２５〜０．０６Ｎ／ｍ、好ましくは０．０３〜０．０５Ｎ／ｍの範囲内の表面張力を有するのが好ましい。上記インクのｐＨは、好ましくは５〜１０であり、特に好ましくは６〜９である。
【０１４１】
【実施例】
以下に、本発明の実施例を挙げて具体的に説明するが、本発明の実施態様はこれらに限定されるものではない。なお、実施例中で記載の「％」は、特に断りのない限り質量％を表す。
【０１４２】
《記録用紙の作製》
〔記録用紙１の作製：比較例〕
予め均一に分散されている気相法シリカ（商品名：Ａ２００、日本アエロジル（株）製、一次粒子の平均粒径　１２ｎｍ）の２３％の分散液Ａ１（ｐＨ２．８、エタノール１質量％含有）の４００ｇに、カチオン性ポリマー（商品名：ＰＡＳ−Ｈ−５Ｌ、日東紡績（株））の２８％水溶液を４０ｇ、ホウ酸１．５ｇ及びホウ砂１．５ｇを含む水溶液５０ｍｌを添加し、高圧ホモジナイザーで分散し、全量を６３０ｍｌに仕上げて、ほぼ透明な分散液Ｂ１を得た。得られた分散液Ｂ１を、３０μｍのろ過精度をもつアドバンテックス東洋社製のＴＣＰ−１０タイプのフィルターを用いてろ過を行った。
【０１４３】
ろ過後、分散液Ｂ１を４３℃で攪拌しながらポリビニルアルコール（商品名：ＰＶＡ２３５、（株）クラレ製）の６％水溶液を２３２ｍｌ加え、界面活性剤（Ｓ−１）を添加して、全体の液が１０００ｍｌになるように純水を加えて、半透明状の塗布液Ｃ１を得た。
【０１４４】
次に、坪量１８０ｇ／ｍ^２の原紙両面をポリエチレンで被覆した支持体（厚さ２５０μｍ、記録面側のポリエチレン層中に６質量％のアナターゼ型チタン含有）の記録面側に、上記の塗布液Ｃ１を湿潤膜厚で１４０μｍになるように塗布し、５℃で１０秒間冷却した後、５５℃の風で乾燥させて記録用紙１を得た。
【０１４５】
【化６】

【０１４６】
〔記録用紙２の作製：比較例〕
上記記録用紙１の作製において、分散液Ａ１の調製に用いた気相法シリカ（商品名：Ａ２００）を、気相法シリカ（商品名：Ａ５０、日本アエロジル（株）製、一次粒子の平均粒径　３０ｎｍ）に変更した以外は同様にして記録用紙２を作製した。
【０１４７】
〔記録用紙３の作製：本発明〕
上記記録用紙１の作製において、分散液Ａ１の調製に用いた気相法シリカ（商品名：Ａ２００）を、気相法シリカ（商品名：ＱＳ−３０、トクヤマ（株）製、一次粒子の平均粒径　７ｎｍ）に変更した以外は同様にして記録用紙３を作製した。
【０１４８】
〔記録用紙４の作製：比較例〕
上記記録用紙１の作製において、分散液Ａ１の調製に用いた気相法シリカ（商品名：Ａ２００）を、コロイダルシリカ（商品名：ＳＴ−ＺＬ、日産化学工業（株）製、一次粒子の平均粒径　８５ｎｍ）に変更した以外は同様にして記録用紙４を作製した。
【０１４９】
〔記録用紙５の作製：本発明〕
予め均一に分散されている気相法シリカ（商品名：ＱＳ−２０、トクヤマ（株）製、一次粒子の平均粒径　１３ｎｍ）の２３％分散液Ａ２（ｐＨ２．８、エタノール１質量％含有）の４００ｇに、カチオン性ポリマー（例示化合物Ｐ−８）の２８％水溶液を４０ｇ、ホウ酸１．５ｇ及びホウ砂１．５ｇを含む水溶液５０ｍｌを添加し、高圧ホモジナイザーで分散し、全量を６３０ｍｌに仕上げて、ほぼ透明な分散液Ｂ２を得た。得られた分散液Ｂ２を、３０μｍのろ過精度を有するアドバンテックス東洋社製のＴＣＰ−１０タイプのフィルターを用いてろ過を行った。
【０１５０】
ろ過後、分散液Ｂ２を４３℃で攪拌しながらポリビニルアルコール（商品名：ＰＶＡ２３５、（株）クラレ製）の６％水溶液を２３２ｍｌ加え、界面活性剤（Ｓ−１）を添加し、全体の液が１０００ｍｌになるように純水を加えて、半透明状の塗布液Ｃ２を得た。
【０１５１】
次に、坪量１８０ｇ／ｍ^２の原紙両面をポリエチレンで被覆した支持体（厚さ２５０μｍ、記録面側のポリエチレン層中に６質量％のアナターゼ型チタン含有）の記録面側に、上記の塗布液Ｃ２を湿潤膜厚で１４０μｍになるように塗布し、５℃で１０秒間冷却した後、５５℃の風で乾燥後、ポリ塩化アルミニウム（商品名：ＰＡＣ２５０Ｌ、多木化学（株）製）の３％水溶液１８０ｇと界面活性剤（Ｓ−１）を１．５ｍｌ添加し全量を１０００ｍｌにし、湿潤膜厚で５０μｍになるように塗布し、７０℃の風で乾燥し、記録用紙５を作製した。
【０１５２】
〔記録用紙６の作製：比較例〕
（上層塗布液の調製）
予め均一に分散されている気相法シリカ（商品名：Ａ３００、日本アエロジル（株）製、一次粒子の平均粒径　７ｎｍ）の２３％分散液Ａ３（ｐＨ２．８、エタノール１質量％含有）の４００ｇに、カチオン性ポリマー（例示化合物Ｐ−８）の２８％水溶液を４０ｇ、ホウ酸１．５ｇ及びホウ砂１．５ｇを含む水溶液５０ｍｌを添加し、高圧ホモジナイザーで分散し、全量を６３０ｍｌに仕上げてほぼ透明な分散液Ｂ３を得た。得られた分散液Ｂ３は、３０μｍのろ過精度を有するアドバンテックス東洋社製のＴＣＰ−１０タイプのフィルターを用いてろ過を行った。
【０１５３】
ろ過後、分散液Ｂ３を４３℃で攪拌しながらポリビニルアルコール（商品名：ＰＶＡ２３５、（株）クラレ製）の６％水溶液を２３２ｍｌ加え、界面活性剤（Ｓ−１）を添加し、全体の液が１０００ｍｌになるように純水を加えて、半透明状の上層塗布液Ｃ３を得た。
【０１５４】
（下層塗布液の調製）
記録用紙２の作製に用いた分散液（無機微粒子；気相法シリカ　商品名：Ａ５０、日本アエロジル（株）製、一次粒子の平均粒径　３０ｎｍ）を４３℃で攪拌しながらポリビニルアルコール（商品名：ＰＶＡ２３５、（株）クラレ製）の６％水溶液を２３２ｍｌ加え、界面活性剤（Ｓ−１）を添加し、全体の液が１０００ｍｌになるように純水を加えて、半透明状の下層塗布液Ｃ４を得た。
【０１５５】
（記録用紙の作製）
次に、坪量１８０ｇ／ｍ^２の原紙両面をポリエチレンで被覆した支持体（厚さ２５０μｍ、記録面側のポリエチレン層中に６質量％のアナターゼ型チタン含有）の記録面側に、上記の上層塗布液Ｃ３と下層塗布液Ｃ４とをそれぞれ湿潤膜厚が７０μｍになるように同時重層塗布し、５℃で１０秒間冷却した後、５５℃の風で乾燥し、記録用紙６を作製した。
【０１５６】
〔記録用紙７の作製：本発明〕
（上層塗布液の調製）
上記上層塗布液Ｃ３の調製において、分散液Ｂ３をろ過した後、４３℃で攪拌しながらポリビニルアルコール（商品名：ＰＶＡ２３５、（株）クラレ製）の６％水溶液を２１９ｍｌ加え、界面活性剤（Ｓ−１）を添加し全体の液が１０００ｍｌになるように純水を加えて、半透明状の上層塗布液Ｃ５を得た。
【０１５７】
（下層塗布液の調製）
記録用紙５の作製に用いた分散液Ｂ２を、４３℃で攪拌しながらポリビニルアルコール（商品名：ＰＶＡ２３５、（株）クラレ製）の６％水溶液を３０６ｍｌ加え、界面活性剤（Ｓ−１）を添加し、全体の液が１０００ｍｌになるように純水を加えて、半透明状の下層塗布液Ｃ６を得た。
【０１５８】
（記録用紙の作製）
次に、坪量１８０ｇ／ｍ^２の原紙両面をポリエチレンで被覆した支持体（厚さ２５０μｍ、記録面側のポリエチレン層中に６質量％のアナターゼ型チタン含有）の記録面側に、上記の上層塗布液Ｃ５と下層塗布液Ｃ６とをそれぞれ湿潤膜厚が７０μｍになるように同時重層塗布し、５℃で１０秒間冷却した後、５５℃の風で乾燥し、記録用紙７を作製した。
【０１５９】
〔記録用紙８の作製：比較例〕
（上層塗布液の調製）
前記記録用紙４の作製において、分散液（無機微粒子；コロイダルシリカ　商品名：ＳＴ−ＺＬ、日産化学工業（株）製、一次粒子の平均粒径　８５ｎｍ）をろ過した後、４３℃で攪拌しながらポリビニルアルコール（商品名：ＰＶＡ２３５、（株）クラレ製）の６％水溶液を２１９ｍｌ加え、界面活性剤（Ｓ−１）を添加し全体の液が１０００ｍｌになるように純水を加えて、半透明状の上層塗布液Ｃ７を得た。
【０１６０】
（下層塗布液の調製）
前記記録用紙６の作製で用いた分散液Ｂ３を、４３℃で攪拌しながらポリビニルアルコール（商品名：ＰＶＡ２３５、（株）クラレ製）の６％水溶液を３０６ｍｌ加え、界面活性剤（Ｓ−１）を添加し全体の液が１０００ｍｌになるように純水を加えて、半透明状の下層塗布液Ｃ８を得た。
【０１６１】
（記録用紙の作製）
坪量１８０ｇ／ｍ^２の原紙両面をポリエチレンで被覆した支持体（厚さ２５０μｍ、記録面側のポリエチレン層中に６質量％のアナターゼ型チタン含有）の記録面側に、上記の上層塗布液Ｃ７と下層塗布液Ｃ８とを、それぞれ湿潤膜厚が７０μｍになるように同時重層塗布し、５℃で１０秒間冷却した後、５５℃の風で乾燥し、記録用紙８を作製した。
【０１６２】
〔記録用紙９の作製：本発明〕
（上層塗布液の調製）
前記記録用紙５の作製に用いた分散液Ｂ２をろ過した後、４３℃で攪拌しながらポリビニルアルコール（商品名：ＰＶＡ２３５、（株）クラレ製）の６％水溶液を２２２ｍｌ加え、界面活性剤（Ｓ−１）を添加し全体の液が１０００ｍｌになるように純水を加えて、半透明状の上層塗布液Ｃ９を得た。
【０１６３】
（下層塗布液の調製）
予め均一に分散されている気相法シリカ（商品名：Ａ５０、日本アエロジル（株）製、一次粒子径　３０ｎｍ）の２３％分散液Ａ４（ｐＨ２．８、エタノール１質量％含有）の４００ｇに、カチオン性ポリマー（例示化合物Ｐ−８）の２８％水溶液を４０ｇ、ホウ酸１．５ｇ及びホウ砂１．５ｇを含む水溶液５０ｍｌを添加し、高圧ホモジナイザーで分散し、全量を６３０ｍｌに仕上げてほぼ透明な分散液Ｂ４を得た。得られた分散液Ｂ４は、３０μｍのろ過精度をもつ、アドバンテックス東洋社製のＴＣＰ−１０タイプのフィルターを用いてろ過を行った。
【０１６４】
ろ過後、分散液Ｂ４を４３℃で攪拌しながらポリビニルアルコール（商品名：ＰＶＡ２３５、（株）クラレ製）の６％水溶液を２５６ｍｌ加え、界面活性剤（Ｓ−１）を添加し全体の液が１０００ｍｌになるように純水を加えて、半透明状の下層塗布液Ｃ１０を得た。
【０１６５】
（記録用紙の作製）
坪量１８０ｇ／ｍ^２の原紙両面をポリエチレンで被覆した支持体（厚さ２５０μｍ、記録面側のポリエチレン層中に６質量％のアナターゼ型チタン含有）上の記録面側に、上記調製した上層塗布液Ｃ７と下層塗布液Ｃ８とを、それぞれ湿潤膜厚が７０μｍになるように同時重層塗布し、５℃で１０秒間冷却した後、５５℃の風で乾燥後、ジルコニウム無機ポリマー（商品名：ジルコゾールＺＣ−２、第一希元素化学工業（株）製）の３％水溶液１８０ｇと界面活性剤（Ｓ−１）を１．５ｍｌ添加して全量を１０００ｍｌにし、湿潤膜厚で５０μｍになるように塗布し、７０℃の風で乾燥し、記録用紙９を得た。
【０１６６】
〔記録用紙１０の作製：本発明〕
前記記録用紙８の作製において、上層塗布液Ｃ７を下層とし、下層塗布液Ｃ８を上層とした以外は同様にして、記録用紙１０を作製した。
【０１６７】
〔記録用紙１１〜１４の作製〕
前記記録用紙２〜５の作製において、カチオン性ポリマーとして、化合物Ａを用いた以外は同様にして、記録用紙１１〜１４を作製した。
【０１６８】
【化７】

【０１６９】
〔記録用紙１５の作製：比較例〕
前記記録用紙４の作製において、無機微粒子として、コロイダルシリカ（商品名：ＳＴ−ＺＬ）に代えて、ＳＴ−ＹＬ（日産化学工業（株）製、一次粒子の平均粒径　６５ｎｍ）を用いた以外は同様にして記録用紙１５を作製した。
【０１７０】
《記録用紙の評価》
以上のようにして作製した記録用紙１〜１５について、下記の測定及び評価を行った。
【０１７１】
（光沢度の測定）
記録面側の光沢度は、日本電色工業社製の光沢度計（ＶＧＳ−１００１ＤＰ）を用いてその６０度光沢度を測定した。
【０１７２】
（Ｃ値の測定）
記録面側のＣ値は、スガ試験機（株）製の写像性測定器（ＩＣＭ−１ＤＰ）を用いて反射６０度を測定した。
【０１７３】
（目視による光沢感の評価）
上記作製した各記録用紙の記録面側の光沢感について、一般の１０人のモニターにより光沢感が良好であるものを１点、普通であるものを０．５点、劣るものを０点として判定して１０人の総合点を求め、下記の基準に則り光沢感の評価を行った。
【０１７４】
◎：総合点が、８点以上である
○：総合点が、６〜７．５点である
△：総合点が、３〜５．５点である
×：総合点が、２．５点以下である
（耐擦性：傷跡の目立ち易さの評価）
全ての用紙に金属片により同程度の力で引っかき傷をつけ、その跡を目視により確認した。
【０１７５】
○：傷跡がほとんど目立たない
×：傷跡がはっきり分かる
（最大濃度の測定）
セイコーエプソン株式会社製のインクジェットプリンターＰＭ９５０Ｃを使用して、ブラックのベタ印字を行いその最大反射濃度を、光学濃度計（Ｘ−Ｒｉｔｅ社製Ｘ−Ｒｉｔｅ９３８）で測定した。
【０１７６】
（高湿滲み耐性の評価）
キヤノン製インクジェットプリンターＢＪＦ８５０で、各記録用紙上にマゼンタのベタ画像をプリントし、その上に線幅が約０．３ｍｍのブラックラインをプリントし、プリントした後、直ちに記録用紙の両面をダミー紙を５枚ずつ積層し、それを５０℃、相対湿度８５％の雰囲気下で７日間保存した。
【０１７７】
以上のようにして処理を行った各試料について、保存前後でのブラックラインの線幅をマイクロデンシトメーターで測定（反射濃度が最大濃度の５０％部分の幅を線幅とした）し、下式に従って滲み率を求め、下記の評価基準に則り滲み耐性の判定を行った。なお、滲み率は、数値が小さいほど滲み耐性に優れていることを示す。
【０１７８】
滲み率＝（画像保存後の線幅）／（画像保存前の線幅）
◎：滲み率が１〜１．２未満
○：滲み率が１．２〜１．３５未満
△：滲み率が１．３５〜１．５未満
×：滲み率が１．５以上
以上により得られた各結果を表１に示す。
【０１７９】
【表１】

【０１８０】
表１より明らかなように、比較の記録用紙に対し、本発明の記録用紙は、印字前の目視による光沢感が良好で、かつ印字前に表面に傷がついても印字後に目立つことなく、高濃度な印字を行うことができ、更に滲み耐性に優れた高画質なインクジェット記録が得られることが分かる。
【０１８１】
【発明の効果】
本発明により、印字前の目視による光沢感が良好で、且つ、印字前に表面に傷がついても印字後に目立つことなく、高濃度な印字を行うことができ、更に滲み耐性に優れた高画質なインクジェット記録が得られるインクジェット記録用紙を提供することができた。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink jet recording paper, and more particularly to an ink jet recording paper having a porous ink absorbing layer on at least one surface.
[0002]
[Prior art]
In recent years, the image quality of ink jet recording has been rapidly improved, and the quality of photographs is approaching. The print quality obtained by ink-jet recording depends on three factors: printer, ink, and ink-jet recording paper. However, in terms of image quality, the two recent technical innovations are significant, and ink-jet recording paper (hereinafter simply referred to as recording paper) ) Performance differences are becoming very important in the final print quality.
[0003]
For this reason, various improvements have conventionally been made from the viewpoint of a recording medium in order to obtain a print similar to a silver halide photographic print by ink jet recording.
[0004]
As the support of the inkjet recording paper, there are a water-absorbing support and a non-water-absorbing support, and the non-water-absorbing support is more likely to cause cockling (wrinkles) after printing as seen in the water-absorbing support. Since there is no occurrence and a high smooth surface can be maintained, a high quality print can be obtained.
[0005]
As the ink absorbing layer provided on the support, a swelling type ink absorbing layer and a void type ink absorbing layer are known.
[0006]
The swellable ink absorbing layer is mainly composed mainly of a hydrophilic polymer such as gelatin, polyvinyl alcohol, polyvinylpyrrolidone or polyethylene oxide. On the other hand, the void-type ink absorbing layer has voids in the layer, and there are several types of manufacturing methods.A typical example is a layer having a small amount of a hydrophilic polymer and a large amount of fine particles. There are gaps formed between the fine particles, which mainly absorb the ink. Recording papers having this void-type ink absorbing layer are becoming one of the ones closest to photographic image quality because of their high gloss, vivid color development, and excellent ink absorption and drying properties. In the present invention, this void-type ink absorbing layer is also called a porous ink absorbing layer, and both are used synonymously.
[0007]
The surface quality of the recording paper may depend on personal preference, but depending on the purpose of use, the glossiness and other properties required as a high-quality print, such as those having a property that makes it difficult for fingerprints to be attached, In some cases, it is required to have a property such that glue or the like is not easily adhered to the surface, a property having a property that the surface is not easily damaged, and a property having a property of preventing reflected light from being too hard to be viewed.
[0008]
Further, as a conventional technique, for example, Japanese Patent Application Laid-Open No. 11-348410 discloses that the 60-degree specular glossiness is 20% or more and the 60-degree specular glossiness of the ink jet recording unit is 3 times higher than that of the unprinted portion where no ink jet recording is performed. % Has been proposed, but the glossiness visually observed is insufficient as inkjet recording paper before printing, and if the surface is scratched before printing (before inkjet recording), There is a problem that the scratch is easily noticeable later (after ink jet recording).
[0009]
Japanese Patent Application Laid-Open No. 2000-355160 discloses that surface roughness and 60-degree specular gloss are specified to reduce glare due to surface gloss without causing a noticeable difference in gloss between printed and non-printed images. Propose to do. Further, JP-A-2001-341410 proposes an ink-jet recording material for backlit in which the glare due to return light is improved by specifying an inorganic pigment, a hydrophilic polymer, a haze value, and image clarity. 347750 contains silica and a cationic compound, suppresses yellowing of white paper by adjusting the film surface pH and the 75 ° surface gloss value, and proposes a recording paper excellent in gloss. However, there is also a problem in that the glossiness by visual inspection is insufficient, and when the surface is scratched before printing, the scratch is easily noticeable after printing.
[0010]
[Problems to be solved by the invention]
An object of the present invention is to provide a high-quality inkjet formed image having excellent glossiness by visual observation before printing, not being noticeable after printing even if the surface before printing is damaged, having high density, and having excellent bleeding resistance. An object of the present invention is to provide an ink jet recording paper.
[0011]
[Means for Solving the Problems]
The above object of the present invention is achieved by the following configurations.
[0012]
1. In an ink jet recording paper having at least one ink absorbing layer on a support, at least one surface of the support has a hydrophilic binder, a cationic compound and inorganic fine particles having an average particle size of primary particles of 50 nm or less. A porous ink-absorbing layer made of the following. The surface of the porous ink-absorbing layer has a 60-degree specular glossiness specified by JIS Z8741 of 30% or more, and a surface specified by JIS K7105. An ink-jet recording sheet having a C value of 65 to 85%.
[0013]
2. 2. The ink jet recording paper according to claim 1, wherein the support is a non-water-absorbing support.
[0014]
3. 3. The ink jet recording paper according to claim 1, wherein the inorganic fine particles are silica fine particles.
[0015]
4. 4. The ink jet recording paper according to any one of items 1 to 3, wherein at least one of the cationic compounds is a cationic polymer having a repeating unit represented by the general formula (1). .
[0016]
5. Wherein at least one of the cationic compounds is a compound having a zirconium atom (however, excluding zirconium oxide) or a compound having an aluminum atom (however, excluding aluminum oxide). The inkjet recording paper according to any one of claims 1 to 7.
[0017]
6. 6. The ink jet recording paper according to any one of items 3 to 5, wherein the silica fine particles are fumed silica.
[0018]
The present inventors have conducted intensive studies on the above problems and found that a porous ink absorbing layer composed of inorganic fine particles, a hydrophilic binder and a cationic compound was formed on the uppermost layer (the surface of at least one surface of the inkjet recording paper). In the ink-jet recording paper of the above, the glossiness visually observed before printing does not necessarily correlate only with the specular glossiness. The 60-degree specular glossiness of the surface of the uppermost layer and the C value are determined by a specific value. By setting to, it is possible to obtain an ink jet recording paper which has a good glossiness by visual observation before printing and which can realize a high-density and high-quality printed image without being noticeable after printing even if the surface before printing is damaged. It has been found that the present invention has been reached.
[0019]
Specifically, when the 60-degree specular glossiness specified by JIS Z8741 is 30% or more and the C value specified by JIS K7105 is 65 to 85%, the surface has a glare and is calm. Good feeling of gloss by visual observation before printing without feeling unpleasant unpleasant glossiness, high density printed image can be obtained without noticeable after printing even if the surface before printing is scratched, It has been found that an ink jet recording paper capable of high quality ink jet recording can be obtained.
[0020]
Hereinafter, the present invention will be described in detail.
In the invention according to claim 1, in an ink jet recording sheet having at least one ink absorbing layer on a support, at least one surface of the support has an average particle size of a hydrophilic binder, a cationic compound and primary particles. It has a porous ink absorbing layer made of inorganic fine particles having a diameter of 50 nm or less, and the surface of the porous ink absorbing layer has a 60-degree specular glossiness specified by JIS Z8741 of 30% or more. And the C value specified in JIS K7105 is 65 to 85%.
[0021]
The C value according to the present invention is image sharpness defined by JIS K7105, and the value is represented by the following equation.
[0022]
C = {(M−m) / (M + m)} × 100
In the formula, C represents the image sharpness (%), M represents the maximum value of the transmitted light of the transparent portion, and m represents the minimum value of the opaque portion.
[0023]
In general, a larger C value indicates higher sharpness, and a smaller C value indicates "blur" or "distortion".
[0024]
This C value is a value that is almost determined by three factors: fine irregularities on the surface, macro smoothness of the surface, and transparency of the uppermost layer of the coating.
[0025]
In the inkjet recording paper of the present invention, in order to make the 60-degree specular glossiness specified in the present invention 30% or more and the C value 65% or more and 85% or less, it is used for the uppermost porous ink absorbing layer. It is necessary that the average particle size of the primary particles of the inorganic fine particles described below be 50 nm or less. In addition to this, it can be realized by using the following method.
[0026]
Hereinafter, particularly, an example of an adjustment method for increasing the 60-degree specular gloss and the C value will be described, but the present invention is not limited to only these methods.
[0027]
Method 1: After dispersing in a coating liquid for coating the uppermost ink-absorbing layer on a support in order to reduce the content of coarse particles as much as possible, filtration is performed.
Method 2: reducing the degree of dispersion of the inorganic fine particles in the coating solution,
Method 3: uniform particle size distribution of inorganic fine particles,
Method 4: Before coating film surface is completely dried after coating, press and contact a mirror surface roller under heating to control the surface property,
Method 5: Obtained by adding particles of an organic compound having a relatively uniform particle size distribution to the uppermost ink absorbing layer. The organic compound particles used in this case include particles obtained by emulsifying and dispersing a hydrophobic organic compound, and latex polymer particles. The average particle size of the particles is preferably from 10 to 200 nm. The organic compound particles are added in an amount of about 10 to 50% by mass with respect to the hydrophilic binder of the ink absorbing layer containing the organic compound particles.
[0028]
Furthermore, the following methods 6 to 10 will particularly describe an adjusting method when a gap type ink absorbing layer is laminated other than the uppermost layer on a recording paper having a multi-layered ink absorbing layer.
[0029]
Method 6: The ratio of at least one void ink absorbing layer other than the uppermost layer in the void ink absorbing layer is at least one, preferably at least two, higher than the ratio of the inorganic fine particles contained in the uppermost void ink absorbing layer to the hydrophilic binder. That is. That is, by increasing the ratio of the hydrophilic binder to the inorganic fine particles in at least one void-type ink absorbing layer other than the uppermost layer, the 60-degree specular gloss and the C value can be increased.
[0030]
Method 7: The degree of dispersion of the inorganic fine particles in the uppermost layer is made smaller than the degree of dispersion of the inorganic fine particles in at least one void type ink absorbing layer other than the uppermost layer. The degree of dispersion refers to a value represented by the ratio of standard deviation / average particle diameter, which is obtained by measuring the particle diameter of an arbitrary number of 100 inorganic fine particles and calculating from the equivalent spherical particle diameter obtained by the particle diameter distribution measurement. Show. The degree of dispersion of the uppermost layer is preferably 1.8 or less.
[0031]
Method 8: This is a method in which inorganic fine particles having different average particle diameters are used for the void-type ink absorption layer as primary particles of the inorganic fine particles forming the void-type ink absorption layer. At least one void-type ink absorbing layer other than the uppermost layer has an inorganic particle having an average particle diameter of primary particles of 2 nm or more, preferably 5 nm or more, and different from the primary particles of the inorganic fine particles of the uppermost ink absorbing layer. This can be achieved by using fine particles. In this case, the average particle size of the primary particles of the inorganic fine particles in the uppermost layer is the smallest among the plurality of void-type ink absorbing layers, and the average particle size of the primary particles of the inorganic fine particles in the uppermost layer is 15 nm or less. This is also preferable because it does not decrease.
[0032]
Method 9: When preparing a coating liquid for forming the uppermost ink absorbing layer in order to reduce the number of coarse particles of the inorganic fine particles forming the uppermost void type ink absorbing layer, the gaps other than the uppermost layer are adjusted. This can be achieved by dispersing with a filter having a filtration accuracy finer than that of the ink absorbing layer and then filtering.
[0033]
Method 10: There is a method in which a swellable ink-absorbing layer is provided on a support, and a void-type ink-absorbing layer of the present invention is provided on the uppermost layer. The swellable ink absorbing layer referred to here is a layer whose thickness increases by swelling action when absorbing ink or water, and the layer is mainly composed of a hydrophilic binder. The swellable ink-absorbing layer may contain an inorganic pigment, and the amount of the inorganic pigment used is about 3 times or less, preferably 2 times or less, by mass relative to the hydrophilic binder. This hydrophilic binder may be the same as or different from the hydrophilic binder constituting the void-type ink absorbing layer. Preferred hydrophilic binders used in the swellable ink absorbing layer are gelatin, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene oxide and mixtures thereof. Particularly, it is preferable that at least one kind is gelatin. Being hardened by the hydrophilic binder contained in these swellable ink absorbing layers and a hardener capable of crosslinking with the hydrophilic binder, it does not cause cracking when applying the void type ink absorbing layer thereon. Is preferred. The amount of the hydrophilic binder used in the swellable ink absorbing layer is 1 m of recording paper. ² The weight is approximately 0.1 to 3 g. When the ink absorbing layer has a two-layer structure, the swelling type ink absorbing layer and the void type ink absorbing layer (top layer) may be simultaneously coated, or the swelling type ink absorbing layer may be coated and dried to form the void type ink absorbing layer. The latter may be applied, but the latter is preferred because it has less cracks.
[0034]
In the present invention, examples of the above-described methods for satisfying the 60-degree specular glossiness of 30% or more and the C value of 65 to 85% may be performed alone or in combination of two or more.
[0035]
Hereinafter, the details of the inkjet recording paper of the present invention will be described.
The main components of the porous ink absorbing layer according to the present invention are a hydrophilic binder, a cationic compound, and inorganic fine particles whose primary particles have an average particle size of 50 nm or less.
[0036]
As the ink absorbing layer of the ink jet recording paper of the present invention, except for the ink absorbing layer provided as the uppermost layer, it is possible to use a swelling type or void type ink absorbing layer or an ink absorbing layer composed of a combination thereof. it can. The ink absorbing layer can be provided on one side or both sides of the support.
[0037]
The inorganic fine particles used in the ink absorbing layer (gap type ink absorbing layer) provided on the uppermost layer of the inkjet recording paper of the present invention will be described.
[0038]
The inorganic fine particles described below can also be used for a void type ink absorbing layer provided thereunder as necessary.
[0039]
As the inorganic fine particles that can be used in the present invention, various types of solid fine particles that are conventionally known for inkjet recording paper can be used.
[0040]
Examples of the inorganic fine particles 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. White inorganic pigments such as, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide and the like. Can be.
[0041]
The inorganic fine particles may be used in a state of being uniformly dispersed in a binder as primary particles, or may be added in a state of forming secondary aggregated particles and being dispersed in a binder, The latter is more preferable from the viewpoint of achieving high ink absorption.
[0042]
The shape of the inorganic fine particles is not particularly limited in the present invention, and may be spherical, rod-like, needle-like, plate-like, or rosary-like.
[0043]
When used in the outermost layer as the inorganic fine particles according to the present invention, the average particle diameter of the primary particles is characterized by being 50 nm or less, and more preferably 20 nm or less. However, the inorganic fine particles used in layers other than the outermost layer are not particularly limited, but preferably have an average primary particle size of 100 nm or less, more preferably 50 nm or less.
[0044]
As the inorganic fine particles according to the present invention, even composite particles composed of inorganic fine particles and a small amount of an organic substance (either a low-molecular compound or a high-molecular compound) are substantially regarded as inorganic fine particles. The mass ratio of organic / inorganic fine particles in the composite particles of the above-mentioned inorganic fine particles and a small amount of organic substance is generally 1/100 to 1/4.
[0045]
The inorganic fine particles according to the present invention are preferably low-refractive-index fine particles from the viewpoint of obtaining a low cost and a high reflection density, and silica fine particles, among which silica fine particles synthesized by a gas phase method, are more preferable. . In addition, fumed silica treated with a cation surface can also be used.
[0046]
The amount of 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 inorganic fine particles, and the type of hydrophilic binder. ² Per hit, it is usually 3 to 30 g, preferably 5 to 25 g. The mass ratio of the inorganic fine particles to the hydrophilic binder used in the ink absorbing layer is usually from 2: 1 to 20: 1, and particularly preferably from 3: 1 to 10: 1.
[0047]
Although the ink absorption capacity increases with the addition amount of the inorganic fine particles, curling and cracking are liable to deteriorate. Therefore, a method of increasing the capacity by controlling the porosity is preferable. Preferred porosity is 40-75%. The porosity can be adjusted by the type of inorganic fine particles and binder selected, or by their mixing ratio, or by the amount of other additives.
[0048]
The porosity here is the ratio of the total volume of the voids to the volume of the void layer, and is calculated from the total volume of the components of the layer and the thickness of the layer. Further, the total volume of the voids can be easily obtained by measuring the saturated transition amount by Bristow measurement, water absorption amount, and the like.
[0049]
Next, the hydrophilic binder according to the present invention will be described.
The hydrophilicity in the present invention means that the compound is soluble in a mixed solvent of water and a water-miscible organic solvent such as methanol, isopropyl alcohol, acetone, and ethyl acetate, in addition to the case where the compound is simply soluble in water. Say In this case, the amount of the water-miscible organic solvent is usually 50% by mass or less based on the total amount of the solvent.
[0050]
The term "hydrophilic binder" refers to a binder that is normally dissolved in the above-mentioned solvent at room temperature by 1% by mass or more, more preferably 3% by mass or more.
[0051]
As the hydrophilic binder used in the present invention, for example, polyvinyl alcohol, gelatin, polyethylene oxide, polyvinylpyrrolidone, casein, starch, agar, carrageenan, polyacrylic acid, polymethacrylic acid, polyacrylamide, polymethacrylamide, polystyrenesulfonic acid, Examples include hydrophilic polymers such as cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, dextran, dextrin, pullulan, and water-soluble polyvinyl butyral. Two or more of these hydrophilic polymers can be used in combination.
[0052]
The hydrophilic polymer preferably used in the present invention is polyvinyl alcohol. The polyvinyl alcohol includes not only ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, but also modified polyvinyl alcohol such as polyvinyl alcohol having a cation-modified terminal and anion-modified polyvinyl alcohol having an anionic group.
[0053]
The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 1000 or more, particularly preferably has an average degree of polymerization of 1500 to 5000, and further has a degree of saponification of 70 to 100%. Is preferable, and 80 to 99.5% is particularly preferable.
[0054]
As the cation-modified polyvinyl alcohol, for example, as described in JP-A-61-10483, having a primary to primary amino group or a 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.
[0055]
Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamido-2,2-dimethylethyl) ammonium chloride, 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.
[0056]
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.
[0057]
Examples of the anion-modified polyvinyl alcohol include, for example, polyvinyl alcohol having an anionic group as described in JP-A-1-2060888 and 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.
[0058]
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.
[0059]
Furthermore, as the modified polyvinyl alcohol, polyvinyl alcohol modified with a silyl group is also included in the polyvinyl alcohol in the present invention.
[0060]
Further, two or more kinds of polyvinyl alcohols having different degrees of polymerization, saponification degree, modification and the like may be used in combination.
[0061]
Gelatin, polyethylene oxide or polyvinylpyrrolidone may be used in combination with polyvinyl alcohol, but these hydrophilic polymers are preferably in the range of 0 to 50% by mass, particularly preferably 0 to 20% by mass, based on polyvinyl alcohol. Can be used.
[0062]
When polyvinyl alcohol is used as the hydrophilic binder, a crosslinking agent is preferably contained in the void layer in order to improve the film forming property of the film and to increase the water resistance and strength of the film.
[0063]
Examples of such a crosslinking agent include boric acid or a salt thereof, an epoxy-based crosslinking agent (eg, diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl) Cyclohexane, N, N-diglycidyl-4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc., aldehyde-based crosslinking agents (eg, formaldehyde, glyoxal, etc.), active halogen-based crosslinking agents (eg, 2,4) -Dichloro-4-hydroxy-1,3,5-s-triazine and the like), active vinyl compounds (for example, 1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether and the like), aluminum Alum, isoshi Sulfonate compounds and the like, and among them, boric acid or a salt thereof.
[0064]
The boric acid or a salt thereof refers to an oxygen acid having a boron atom as a central atom and a salt thereof, and specifically, orthoboric acid, metaboric acid, hypoboric acid, tetraboric acid, pentaboric acid and a salt thereof. Is included.
[0065]
The amount of boric acid or a salt thereof may vary widely depending on the amount of the inorganic fine particles and the hydrophilic binder in the coating solution, but is generally 1 to 60% by mass, preferably 5 to 40% by mass based on the hydrophilic binder. .
[0066]
The cross-linking agent such as boric acid or a salt thereof may be added to the water-soluble coating solution for forming the porous layer used in the present invention when the coating solution is applied, or the cross-linking agent containing no cross-linking agent may be added. After applying and drying a water-soluble coating solution for forming a porous layer, the solution can be supplied by overcoating a solution containing a crosslinking agent.
[0067]
In the present invention, in addition to the boric acid, the above-mentioned other crosslinking agent can be used in combination.
[0068]
The amount of the cross-linking agent used varies depending on the type of the hydrophilic binder, the type of the cross-linking agent, the type of the inorganic fine particles, the ratio to the hydrophilic binder, and the like.For example, when using polyvinyl alcohol as the hydrophilic binder, The amount is 5 to 500 mg, preferably 10 to 300 mg, per 1 g of polyvinyl alcohol.
[0069]
Next, the cationic compound according to the present invention will be described.
The cationic compound according to the present invention is preferably a cationic polymer and / or a polyvalent metal compound.
[0070]
The cationic polymer is a polymer having a tertiary amine, a quaternary ammonium base, a quaternary phosphonium base, or the like in the polymer main chain or side chain, and a compound known in inkjet recording paper is used. From the standpoint of ease of production, those which are substantially water-soluble are preferred.
[0071]
Examples of the cationic polymer used in the present invention include polyethyleneimine, polyallylamine, polyvinylamine, dicyandiamide polyalkylenepolyamine condensate, polyalkylenepolyamine dicyandiamidammonium salt condensate, dicyandiamide formalin condensate, epichlorohydrin / dialkylamine addition polymerization Product, diallyl dimethyl ammonium chloride polymer, diallyl dimethyl ammonium chloride / SO ₂ Copolymer, polyvinylimidazole, vinylpyrrolidone / vinylimidazole copolymer, polyvinylpyridine, polyamidine, chitosan, cationized starch, vinylbenzyltrimethylammonium chloride polymer, (2-methacryloyloxyethyl) trimethylammonium chloride polymer, dimethyl Examples thereof include aminoethyl methacrylate polymers, and one or more of them can be used.
[0072]
Alternatively, a cationic polymer described in the Chemical Industry Times August 15, 25, 1998, and a polymeric dye fixing agent described in “Introduction to Polymeric Drugs” issued by Sanyo Chemical Industries, Ltd. may be mentioned as examples.
[0073]
In the invention according to claim 5, it is preferable that at least one of the cationic compounds is a cationic polymer having a repeating unit represented by the general formula (1).
[0074]
In the general formula (1), the alkyl group represented by R is preferably a methyl group. R ₁ , R ₂ And R ₃ The alkyl group represented by is preferably a methyl group, an ethyl group, or a benzyl group. The divalent organic group represented by J preferably represents -CON (R ')-. R 'represents a hydrogen atom or an alkyl group.
[0075]
Examples of the anion group represented by X include a halogen ion, an acetate ion, a methyl sulfate ion, and a p-toluenesulfonic acid salt.
[0076]
The preferred cationic polymer may be a homopolymer composed of the repeating unit represented by the general formula (1), or may be a copolymer with another copolymerizable monomer. Examples of the copolymerizable repeating unit include a cationic monomer other than the general formula (1) and a monomer having no cationic group.
[0077]
Examples of the monomer having a cationic group include the following repeating units.
[0078]
Embedded image

[0079]
As the copolymerizable repeating unit having no cationic group, for example, ethylene, styrene, butadiene, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, Octyl acrylate, hydroxylethyl methacrylate, acrylamide, vinyl acetate, vinyl methyl ether, vinyl chloride, 4-vinylpyridine, N-vinylpyrrolidone, N-vinylimidazole, acrylonitrile and the like can be mentioned.
[0080]
When the cationic polymer according to the present invention has a repeating unit represented by the general formula (1), the proportion of the repeating unit represented by the general formula (1) is preferably 20 mol% or more, particularly preferably 40 mol% or more. １００100 mol%.
[0081]
Specific examples of the cationic polymer having a repeating unit represented by the general formula (1) according to the present invention are shown below, but the present invention is not limited thereto.
[0082]
Embedded image

[0083]
Embedded image

[0084]
Embedded image

[0085]
The weight average molecular weight of the cationic polymer is preferably in the range of 2000 to 500,000, and more preferably in the range of 3000 to 100,000.
[0086]
When the cationic polymer according to the present invention is previously added to a coating solution, it may be added not only uniformly to the coating solution but also in a form of forming composite particles together with inorganic fine particles. As a method of preparing composite particles by using inorganic fine particles and a cationic polymer, a method of mixing a cationic polymer with inorganic fine particles and adsorbing and coating the same, a method of aggregating the coated particles to obtain higher-order composite particles, and a method of further mixing A method in which coarse particles obtained by the above method are made into more uniform composite particles by a disperser.
[0087]
Cationic polymers generally exhibit water solubility because they have water-soluble groups, but may not be dissolved in water depending on, for example, the composition of the copolymerization component. It is preferably water-soluble for ease of production. However, even if it is hardly soluble in water, it can be dissolved in a water-miscible organic solvent and used.
[0088]
Here, the water-miscible organic solvent includes alcohols such as methanol, ethanol, isopropanol and n-propanol, glycols such as ethylene glycol, diethylene glycol and glycerin, esters such as ethyl acetate and propyl acetate, acetone and methyl ethyl ketone. And organic solvents such as amides such as N, N-dimethylformamide, which can be dissolved in water by about 10% or more. In this case, the amount of the organic solvent used is preferably equal to or less than the amount of water used.
[0089]
Cationic polymer is 1m inkjet recording paper ² The amount is usually 0.1 to 10 g, preferably 2 to 5 g.
[0090]
In the invention according to claim 6, it is preferable that at least one of the cationic compounds is a compound having a zirconium atom (however, excluding zirconium oxide) or a compound having an aluminum atom (however, excluding aluminum oxide).
[0091]
Specific examples of the compound having a zirconium atom include zirconium difluoride, zirconium trifluoride, zirconium tetrafluoride, hexafluorozirconate (eg, potassium salt), and heptafluorozirconate (eg, sodium salt, potassium salt) Salts and ammonium salts), octafluorozirconate (eg, lithium salt), zirconium fluoride oxide, zirconium dichloride, zirconium trichloride, zirconium tetrachloride, hexachlorozirconate (eg, sodium and potassium salts), acids Zirconium chloride (eg, zirconyl chloride), zirconium dibromide, zirconium tribromide, zirconium tetrabromide, zirconium bromide, zirconium triiodide, zirconium tetraiodide, zirconium peroxide, zirconium hydroxide Zirconium sulfide, zirconium sulfate, zirconium p-toluenesulfonate, zirconyl sulfate, sodium zirconyl sulfate, zirconyl sulfate trihydrate, potassium zirconium sulfate, zirconium selenate, zirconium nitrate, zirconyl nitrate, zirconium phosphate, zirconyl carbonate, carbonate Zirconyl ammonium, zirconium acetate, zirconyl acetate, zirconyl acetate, zirconyl lactate, zirconyl citrate, zirconyl stearate, zirconium phosphate, zirconyl phosphate, zirconium oxalate, zirconium isopropylate, zirconium butyrate, zirconium acetylacetonate, acetylacetone Zirconium butyrate, zirconium butyrate stearate, zirconium acetate, bis ( Sechiruasetonato) dichlorozirconium, tris (acetylacetonato) such as chloro zirconium are exemplified.
[0092]
Specific examples of the compound having an aluminum atom include aluminum fluoride, hexafluoroaluminic acid (eg, potassium salt), aluminum chloride, basic aluminum chloride (eg, polyaluminum chloride), and tetrachloroaluminate (eg, Sodium salt), aluminum bromide, tetrabromoaluminate (eg, potassium salt), aluminum iodide, aluminate (eg, sodium salt, potassium salt, calcium salt, etc.), aluminum chlorate, perchloric acid Aluminum, aluminum thiocyanate, aluminum sulfate, basic aluminum sulfate, aluminum potassium sulfate (alum), ammonium aluminum sulfate (ammonium alum), sodium aluminum sulfate, aluminum phosphate, aluminum nitrate , Aluminum hydrogen phosphate, aluminum carbonate, aluminum polysulfate silicate, aluminum formate, aluminum acetate, aluminum lactate, aluminum oxalate, aluminum isopropylate, aluminum butyrate, ethyl acetate aluminum diisopropylate, aluminum tris (acetylacetonate), aluminum tris (Ethyl acetoacetate), aluminum monoacetylacetonate bis (ethyl acetoacetonate) and the like.
[0093]
Among the compounds having a zirconium atom or an aluminum atom according to the present invention (excluding zirconium oxide and aluminum oxide), a polyaluminum chloride compound, a polyaluminum sulfate, a polyaluminum silicate compound or a zirconium-based active inorganic polymer may be used. Most preferred.
[0094]
The polyaluminum chloride compound has the general formula [Al ₂ (OH) _n Cl _6-n ] _m , [Al (OH) ₃ ] _n ・ AlCl ₃ And, for example, [Al ₆ (OH) _Fifteen ] ³⁺ , [Al ₈ (OH) ₂₀ ] ⁴⁺ , [Al ₁₃ (OH) ₃₄ ] ⁵⁺ It is a polyaluminum chloride which stably contains a basic polynuclear condensed ion (polymer) having a high positron as an active ingredient.
[0095]
Commercially available polyaluminum chloride compounds include, for example, polyaluminum hydroxide (Paho) manufactured by Asada Chemical Co., Ltd., polyaluminum chloride (PAC) manufactured by Taki Chemical Co., Ltd., and Purachem manufactured by Riken Green Co., Ltd. WT.
[0096]
The polyaluminum sulfate compound has a general formula [Al ₂ (OH) _n (SO ₄ ) _{6-n / 2} ] _m (Where 0 <n <6), and commercially available products include basic aluminum sulfate (AHS) manufactured by Asada Chemical Co., Ltd.
[0097]
As a commercial product of the aluminum polysulfate silicate compound, PASS manufactured by Nippon Light Metal Co., Ltd. is exemplified.
[0098]
Commercially available zirconium oxychloride-based inorganic polymers include Zircosol ZC-2 manufactured by Daiichi Kazoku Kagaku Kogyo Co., Ltd.
[0099]
The cationic compound according to the present invention may be added to the coating liquid for the porous ink absorbing layer and then dried by coating, or the porous ink absorbing layer may be impregnated with the aqueous solution after drying after coating. May be added. Further, a method of adding the porous ink absorbing layer after application and before drying may be used. Examples of the method of adding the porous ink absorbing layer after coating and before drying include an overcoating method, curtain coating, spray coating, and the like.
[0100]
When the cationic compound according to the present invention is added to the coating liquid for forming the porous ink absorbing layer, it may be uniformly dissolved in water or an organic solvent or a mixed solvent thereof, or wet pulverized by a sand mill or the like. It can be dispersed and added to fine particles by a method such as emulsification and dispersion. When the porous ink absorption layer is composed of a plurality of layers, only one layer may be added, or two or more layers or all layers may be added to the coating liquid.
[0101]
In addition, when a porous ink absorbing layer is formed once and then added by an overcoating method, it is preferable to dissolve it in a uniform solution and then add it. Further, two or more cationic compounds may be used in combination.
[0102]
Other than the above, for example, ultraviolet absorbers, anionic, cationic or nonionic surfactants described in JP-A-57-74193, JP-A-57-87988 and JP-A-62-261476, JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-242871, JP-A-4-219266, and the like, a fluorescent whitening agent, an antifoaming agent, Various known additives such as a lubricant such as diethylene glycol, a preservative, a thickener, an antistatic agent, and a matting agent can be contained.
[0103]
In the invention according to claim 2, the support is preferably a non-water-absorbing support.
[0104]
As the support of the inkjet recording paper of the present invention, a water-absorbing or non-water-absorbing support can be used, but the non-water-absorbing support has no wrinkles after printing and has a smooth image. This is preferable because high-quality prints can be obtained without any difference.
[0105]
The water-absorbing support is generally a paper support, but also includes a cloth or a porous film support.
[0106]
In addition, as the non-water-absorbing support, materials such as polyethylene terephthalate resin, polyester resin, diacetate resin, triacetate resin, acrylic resin, polycarbonate resin, polyvinyl chloride resin, polyimide resin, cellophane, celluloid, etc. Examples of the film include metal and glass, resin-coated paper having a polyethylene resin coating layer (so-called RC paper), and white pet obtained by adding a white pigment to polyethylene terephthalate.
[0107]
Among them, it is particularly preferable to use a paper support in which both sides of a base paper support are laminated with polyethylene, since a recorded image is close to a photographic quality and a high-quality image can be obtained at low cost.
[0108]
Hereinafter, a support in which both surfaces of a paper, which is a particularly preferred support in the present invention, are coated with a polyolefin resin will be described.
[0109]
The paper used for the support according to the present invention is made from wood pulp as a main raw material, and if necessary, in addition to wood pulp, using synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester. As the wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, and NUKP can be used, but it is preferable to use LBKP, NBSP, LBSP, NDP, and LDP which contain a large amount of short fibers. However, the ratio of LBSP and / or LDP is preferably 10 to 70%. As the pulp, chemical pulp (sulfate pulp or sulfite pulp) having a small amount of impurities is preferably used, and pulp having improved whiteness by performing a bleaching treatment is also useful.
[0110]
In paper, for example, higher fatty acids, sizing agents such as alkyl ketene dimer, white pigments such as calcium carbonate, talc, titanium oxide, paper strength enhancers such as starch, polyacrylamide, polyvinyl alcohol, fluorescent whitening agents, polyethylene A water retention agent such as glycols, a dispersant, a softening agent such as quaternary ammonium, and the like can be appropriately added.
[0111]
The freeness of the pulp used for papermaking is preferably 200 to 500 ml according to the CSF specification, and the sum of the 24 mesh residue and the 42 mesh residue whose fiber length after beating is specified in JIS P 8207 is 30 to 50. 70% is preferred. In addition, it is preferable that the 4 mesh residue is 20% or less.
[0112]
The basis weight of the paper is preferably from 50 to 250 g, and particularly preferably from 70 to 200 g. The thickness of the paper is preferably 50 to 210 μm.
[0113]
The paper can also be calendered at the papermaking stage or after papermaking to provide high smoothness. 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.
[0114]
A surface sizing agent may be applied to the paper surface, and the same sizing agent that can be added to the base paper can be used as the surface sizing agent.
[0115]
The pH of the paper is preferably 5 to 9 when measured by the hot water extraction method specified in JIS P 8113.
[0116]
Next, the polyolefin resin covering both sides of the paper will be described.
Examples of the polyolefin resin used for this purpose include polyethylene, polypropylene, polyisobutylene, and polyethylene. Polyolefins such as a copolymer mainly composed of propylene are preferable, and polyethylene is particularly preferable.
[0117]
Hereinafter, particularly preferred polyethylene will be described.
The polyethylene that covers the front and back surfaces of the paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but other LLDPE, polypropylene, and the like can also be partially used.
[0118]
In particular, the polyolefin layer on the coating layer side preferably has improved opacity and whiteness by adding rutile or anatase type titanium oxide therein. The titanium oxide content is generally 1 to 20%, preferably 2 to 15%, based on the polyolefin.
[0119]
In the polyolefin layer, a color pigment having high heat resistance and a fluorescent whitening agent for adjusting a white background can be added.
[0120]
Examples of the coloring pigment include ultramarine, navy blue, cobalt blue, phthalocyanine blue, manganese blue, cerulean, tungsten blue, molybdenum blue, anthraquinone blue, and the like.
[0121]
Examples of the fluorescent whitening agent include dialkylaminocoumarin, bisdimethylaminostilbene, bismethylaminostilbene, 4-alkoxy-1,8-naphthalenedicarboxylic acid-N-alkylimide, bisbenzoxazolylethylene, dialkylstilbene and the like. Is mentioned.
[0122]
The amount of polyethylene used on the front and back of the paper is selected so as to optimize the thickness of the ink absorbing layer and the curl in low and high humidity after providing the back layer. Is 15 to 50 μm on the ink absorbing layer side and 10 to 40 μm on the back layer side. The ratio of the front and back polyethylene is preferably set so as to adjust the curl that changes depending on the type and thickness of the ink receiving layer, the thickness of the inner paper, and the like. 3/1 to 1/3.
[0123]
Further, the paper support coated with the polyethylene preferably has the following properties (1) to (7).
[0124]
(1) Tensile strength: The strength specified in JIS P 8113 is preferably 19.6 to 294 N in the vertical direction and 9.8 to 196 N in the horizontal direction.
[0125]
(2) Tear strength: The strength specified in JIS P 8116 is preferably 0.20 to 2.94 N in the vertical direction and 0.098 to 2.45 N in the horizontal direction.
[0126]
(3) Compression modulus: 9.8 kN / cm ² Is preferred.
(4) Opacity: When measured by the method specified in JIS P 8138, it is preferably 80% or more, particularly preferably 85 to 98%.
[0127]
(5) Whiteness: L defined by JIS Z 8727 ^* , A ^* , B ^* Is L ^* = 80-96, a ^* = -3 to +5, b ^* = −7 to +2.
[0128]
(6) Clark stiffness: Clark stiffness in the conveyance direction of the recording paper is 50 to 300 cm ³ / 100 is preferred.
[0129]
(7) The moisture in the base paper is preferably 4 to 10% based on the middle paper.
(8) The glossiness (75-degree specular glossiness) at which the ink receiving layer is provided is preferably 10 to 90%.
[0130]
(Other components of inkjet recording paper)
In the ink jet recording paper of the present invention, a method of applying various layers appropriately provided as necessary, such as a porous ink absorbing layer and an undercoat layer, on a support can be appropriately selected from known methods. . A preferable method is obtained by applying a coating solution constituting each layer on a support and drying the coating solution. In this case, two or more layers can be applied simultaneously, and in particular, simultaneous application in which all the hydrophilic binder layers need only be applied once is preferable.
[0131]
As a 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.
[0132]
The film surface pH of the recording surface of the ink jet recording paper of the invention is preferably from 3.0 to 7.5. When the film surface pH is 3.0 or more, it is possible to prevent so-called bronzing in which a dye precipitates and changes in gloss to a metallic shape when recording by ink jet, and if the film surface pH is 7.5 or less, Sufficient bleeding resistance can be exhibited.
[0133]
The measurement of the film surface pH of the recording surface of the ink jet recording paper of the present invention is described in J. Org. TAPPI paper pulp test method No. According to the method described in No. 49, it can be determined by a method of measuring after 30 seconds using distilled water.
[0134]
In the present invention, the pH of the film surface of the recording surface can be adjusted to a predetermined range by adjusting the pH of the coating liquid forming the recording surface. Further, after forming the recording surface, a predetermined range can be obtained by overcoating with a suitable pH adjuster. As the pH adjuster, an aqueous solution of an appropriate acid or alkali can be used. In this case, the type and concentration of the acid or alkali to be used can be appropriately selected depending on the pH range to be adjusted.
[0135]
The ink jet recording paper of the present invention has a particularly large effect particularly in ink jet recording using a water-soluble dye ink, but can also be used in ink jet recording using a pigment ink.
[0136]
When performing image recording using the inkjet recording paper of the present invention, a recording method using an aqueous ink is preferably used.
[0137]
The aqueous ink is a recording liquid having the following colorant, solvent, and other additives. As the colorant, a water-soluble dye or a water-dispersible pigment such as a direct dye, an acid dye, a basic dye, a reactive dye, or a food colorant known by inkjet can be used.
[0138]
Examples of the solvent for the aqueous ink include water and various water-soluble organic solvents, for example, alcohols such as methyl alcohol, isopropyl alcohol, butyl alcohol, tert-butyl alcohol, and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; Ketones or ketone alcohols such as diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6 -Polyhydric alcohols such as hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, glycerin, and triethanolamine , Ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, lower alkyl ethers of polyhydric alcohols such as triethylene glycol monobutyl ether. Of these, polyhydric alcohols such as diethylene glycol, triethanolamine and glycerin, and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monobutyl ether are preferred.
[0139]
Examples of other water-based ink additives include a pH adjuster, a metal sequestering agent, a fungicide, a viscosity adjuster, a surface tension adjuster, a wetting agent, a surfactant, and a rust inhibitor.
[0140]
The aqueous ink liquid has a surface tension at 20 ° C. of usually from 0.025 to 0.06 N / m, preferably from 0.03 to 0.05 N / m, in order to improve the wettability to recording paper. It is preferred to have The pH of the ink is preferably from 5 to 10, particularly preferably from 6 to 9.
[0141]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples, but embodiments of the present invention are not limited thereto. In addition, "%" described in the examples represents mass% unless otherwise specified.
[0142]
《Preparation of recording paper》
[Preparation of Recording Paper 1: Comparative Example]
23% dispersion A1 (pH 2.8, containing ethanol 1% by mass) of fumed silica (trade name: A200, manufactured by Nippon Aerosil Co., Ltd., average particle size of primary particles: 12 nm), which has been uniformly dispersed in advance. 40 g of a 28% aqueous solution of a cationic polymer (trade name: PAS-H-5L, Nitto Boseki), 50 ml of an aqueous solution containing 1.5 g of boric acid and 1.5 g of borax were added to 400 g of The mixture was dispersed with a homogenizer, and the total volume was adjusted to 630 ml to obtain a substantially transparent dispersion B1. The obtained dispersion liquid B1 was filtered using a TCP-10 type filter manufactured by Advantex Toyo Co., Ltd. having a filtration accuracy of 30 μm.
[0143]
After filtration, 232 ml of a 6% aqueous solution of polyvinyl alcohol (trade name: PVA235, manufactured by Kuraray Co., Ltd.) was added while stirring the dispersion B1 at 43 ° C., and a surfactant (S-1) was added. Pure water was added to make the solution 1000 ml, thereby obtaining a translucent coating solution C1.
[0144]
Next, a basis weight of 180 g / m ² The above coating solution C1 was coated to a wet film thickness of 140 μm on the recording surface side of a support (thickness 250 μm, containing 6% by mass of anatase type titanium in the polyethylene layer on the recording surface side) coated on both sides of the base paper with polyethylene. After coating at room temperature and cooling at 5 ° C. for 10 seconds, the recording paper 1 was obtained by drying with air at 55 ° C.
[0145]
Embedded image

[0146]
[Preparation of Recording Paper 2: Comparative Example]
In the preparation of the recording paper 1, the fumed silica (trade name: A200) used for the preparation of the dispersion A1 was replaced with the fumed silica (trade name: A50, manufactured by Nippon Aerosil Co., Ltd.) Recording paper 2 was prepared in the same manner except that the diameter was changed to 30 nm.
[0147]
[Preparation of recording paper 3: the present invention]
In the preparation of the recording paper 1, the fumed silica (trade name: A200) used for the preparation of the dispersion liquid A1 was replaced with the fumed silica (trade name: QS-30, manufactured by Tokuyama Corporation, average primary particles). Recording paper 3 was produced in the same manner except that the particle size was changed to 7 nm.
[0148]
[Preparation of Recording Paper 4: Comparative Example]
In the production of the recording paper 1, the fumed silica (trade name: A200) used for the preparation of the dispersion A1 was changed to colloidal silica (trade name: ST-ZL, manufactured by Nissan Chemical Industries, Ltd., average primary particles). Recording paper 4 was produced in the same manner except that the particle size was changed to 85 nm.
[0149]
[Preparation of recording paper 5: the present invention]
23% dispersion A2 (pH 2.8, containing ethanol 1% by mass) of fumed silica (trade name: QS-20, manufactured by Tokuyama Co., Ltd., average primary particle size 13 nm), which is uniformly dispersed in advance. Was added to 40 g of a 28% aqueous solution of a cationic polymer (exemplified compound P-8), 50 ml of an aqueous solution containing 1.5 g of boric acid and 1.5 g of borax, and dispersed with a high-pressure homogenizer to make the total amount 630 ml. After finishing, an almost transparent dispersion B2 was obtained. The obtained dispersion liquid B2 was filtered using a TCP-10 type filter manufactured by Advantex Toyo having a filtration accuracy of 30 µm.
[0150]
After filtration, 232 ml of a 6% aqueous solution of polyvinyl alcohol (trade name: PVA235, manufactured by Kuraray Co., Ltd.) was added while stirring the dispersion B2 at 43 ° C., and a surfactant (S-1) was added. Was adjusted to 1000 ml to obtain a translucent coating solution C2.
[0151]
Next, a basis weight of 180 g / m ² The above coating solution C2 was coated to a wet film thickness of 140 μm on the recording surface side of a support (thickness 250 μm, containing 6% by mass of anatase type titanium in the polyethylene layer on the recording surface side) in which both sides of the base paper were coated with polyethylene. After cooling at 5 ° C. for 10 seconds and drying with air at 55 ° C., 180 g of a 3% aqueous solution of polyaluminum chloride (trade name: PAC250L, manufactured by Taki Chemical Co., Ltd.) and a surfactant ( S-1) was added in an amount of 1.5 ml to make the total amount 1000 ml, applied so as to have a wet film thickness of 50 μm, and dried with air at 70 ° C. to produce a recording paper 5.
[0152]
[Preparation of Recording Paper 6: Comparative Example]
(Preparation of upper layer coating solution)
A 23% dispersion A3 (pH 2.8, containing 1% by mass of ethanol) of fumed silica (trade name: A300, manufactured by Nippon Aerosil Co., Ltd., average particle size of primary particles: 7 nm) which has been dispersed uniformly in advance. To 400 g, 40 g of a 28% aqueous solution of a cationic polymer (exemplified compound P-8), 50 ml of an aqueous solution containing 1.5 g of boric acid and 1.5 g of borax were added, and the mixture was dispersed with a high-pressure homogenizer to finish the total amount to 630 ml. Thus, a substantially transparent dispersion B3 was obtained. The obtained dispersion liquid B3 was filtered using a TCP-10 type filter manufactured by Advantex Toyo having a filtration accuracy of 30 µm.
[0153]
After filtration, 232 ml of a 6% aqueous solution of polyvinyl alcohol (trade name: PVA235, manufactured by Kuraray Co., Ltd.) was added while stirring the dispersion B3 at 43 ° C., and a surfactant (S-1) was added. Was adjusted to 1000 ml to obtain a translucent upper layer coating solution C3.
[0154]
(Preparation of lower layer coating solution)
Polyvinyl alcohol (trade name) was stirred at 43 ° C. with the dispersion (inorganic fine particles; fumed silica, trade name: A50, manufactured by Nippon Aerosil Co., Ltd., average particle size 30 nm) used in the production of the recording paper 2. 232 ml of a 6% aqueous solution of PVA235 (manufactured by Kuraray Co., Ltd.), a surfactant (S-1) were added, and pure water was added so that the total solution was 1000 ml. Liquid C4 was obtained.
[0155]
(Preparation of recording paper)
Next, a basis weight of 180 g / m ² The above upper layer coating solution C3 and lower layer coating solution C4 were applied to the recording surface side of a support (thickness 250 μm, containing 6% by mass of anatase type titanium in the polyethylene layer on the recording surface side) in which both sides of the base paper were coated with polyethylene. Was applied simultaneously so that the wet film thickness became 70 μm, cooled at 5 ° C. for 10 seconds, and dried with air at 55 ° C. to produce a recording paper 6.
[0156]
[Preparation of recording paper 7: the present invention]
(Preparation of upper layer coating solution)
In the preparation of the upper layer coating solution C3, after the dispersion B3 was filtered, 219 ml of a 6% aqueous solution of polyvinyl alcohol (trade name: PVA235, manufactured by Kuraray Co., Ltd.) was added with stirring at 43 ° C., and a surfactant (S -1) was added thereto, and pure water was added so that the total liquid might be 1000 ml, to obtain a translucent upper layer coating liquid C5.
[0157]
(Preparation of lower layer coating solution)
While stirring the dispersion liquid B2 used for producing the recording paper 5 at 43 ° C., 306 ml of a 6% aqueous solution of polyvinyl alcohol (trade name: PVA235, manufactured by Kuraray Co., Ltd.) was added, and the surfactant (S-1) was added. Pure water was added so that the total amount of the solution was 1000 ml, to obtain a translucent lower layer coating solution C6.
[0158]
(Preparation of recording paper)
Next, a basis weight of 180 g / m ² The upper layer coating solution C5 and the lower layer coating solution C6 were coated on the recording surface side of a support (thickness 250 μm, containing 6% by mass of anatase titanium in the polyethylene layer on the recording surface side) in which both sides of the base paper were coated with polyethylene. Was applied simultaneously so that the wet film thickness became 70 μm, cooled at 5 ° C. for 10 seconds, and then dried with air at 55 ° C. to produce a recording paper 7.
[0159]
[Preparation of Recording Paper 8: Comparative Example]
(Preparation of upper layer coating solution)
In the preparation of the recording paper 4, the dispersion liquid (inorganic fine particles; colloidal silica, trade name: ST-ZL, manufactured by Nissan Chemical Industries, Ltd., average particle diameter of primary particles: 85 nm) was filtered, and then stirred at 43 ° C. 219 ml of a 6% aqueous solution of polyvinyl alcohol (trade name: PVA235, manufactured by Kuraray Co., Ltd.) was added, a surfactant (S-1) was added, and pure water was added so that the total liquid was 1000 ml. An upper layer coating solution C7 was obtained.
[0160]
(Preparation of lower layer coating solution)
While stirring the dispersion B3 used in the preparation of the recording paper 6 at 43 ° C., 306 ml of a 6% aqueous solution of polyvinyl alcohol (trade name: PVA235, manufactured by Kuraray Co., Ltd.) was added, and a surfactant (S-1) was added. Was added thereto, and pure water was added so that the total liquid might be 1000 ml, to obtain a translucent lower layer coating liquid C8.
[0161]
(Preparation of recording paper)
Basis weight 180g / m ² The above upper layer coating solution C7 and lower layer coating solution C8 were coated on the recording surface side of a support (thickness 250 μm, containing 6% by mass of anatase type titanium in the polyethylene layer on the recording surface side) in which both sides of the base paper were coated with polyethylene. Were simultaneously coated so that the wet film thickness was 70 μm, cooled at 5 ° C. for 10 seconds, and then dried with air at 55 ° C. to produce a recording paper 8.
[0162]
[Preparation of recording paper 9: the present invention]
(Preparation of upper layer coating solution)
After filtering the dispersion liquid B2 used for preparing the recording paper 5, 222 ml of a 6% aqueous solution of polyvinyl alcohol (trade name: PVA235, manufactured by Kuraray Co., Ltd.) was added thereto with stirring at 43 ° C., and a surfactant (S -1) was added thereto, and pure water was added so that the total liquid might be 1000 ml, whereby a translucent upper layer coating liquid C9 was obtained.
[0163]
(Preparation of lower layer coating solution)
To 400 g of a 23% dispersion A4 (pH 2.8, containing 1% by mass of ethanol) of a fumed silica (trade name: A50, manufactured by Nippon Aerosil Co., Ltd., primary particle size: 30 nm), which is uniformly dispersed in advance, 40 g of a 28% aqueous solution of a cationic polymer (exemplified compound P-8), 50 ml of an aqueous solution containing 1.5 g of boric acid and 1.5 g of borax are added, and the mixture is dispersed with a high-pressure homogenizer. A dispersion B4 was obtained. The obtained dispersion liquid B4 was filtered using a TCP-10 type filter manufactured by Advantex Toyo having a filtration accuracy of 30 μm.
[0164]
After filtration, while stirring the dispersion liquid B4 at 43 ° C., 256 ml of a 6% aqueous solution of polyvinyl alcohol (trade name: PVA235, manufactured by Kuraray Co., Ltd.) was added, and a surfactant (S-1) was added. Pure water was added to a volume of 1000 ml to obtain a translucent lower layer coating solution C10.
[0165]
(Preparation of recording paper)
Basis weight 180g / m ² The upper layer coating solution C7 and the lower layer coating solution prepared above were coated on the recording surface side of a support (thickness 250 μm, containing 6% by mass of anatase type titanium in the polyethylene layer on the recording surface side) in which both sides of the base paper were covered with polyethylene. C8 and a multilayer coating simultaneously so that the wet film thickness becomes 70 μm, and after cooling at 5 ° C. for 10 seconds, drying with air at 55 ° C., a zirconium inorganic polymer (trade name: Zircosol ZC-2, first 180 g of a 3% aqueous solution of Rare Element Chemical Industry Co., Ltd.) and 1.5 ml of a surfactant (S-1) were added to make the total amount 1000 ml, and the mixture was applied to a wet film thickness of 50 μm. To obtain recording paper 9.
[0166]
[Preparation of recording paper 10: the present invention]
The recording paper 10 was produced in the same manner as the recording paper 8 except that the upper layer coating solution C7 was used as the lower layer and the lower layer coating solution C8 was used as the upper layer.
[0167]
[Preparation of Recording Papers 11 to 14]
Recording papers 11 to 14 were produced in the same manner as in the production of recording papers 2 to 5, except that Compound A was used as the cationic polymer.
[0168]
Embedded image

[0169]
[Preparation of Recording Paper 15: Comparative Example]
Except for using ST-YL (manufactured by Nissan Chemical Industries, Ltd., average primary particle size 65 nm) instead of colloidal silica (trade name: ST-ZL) as the inorganic fine particles in the preparation of the recording paper 4. Produced recording paper 15 in the same manner.
[0170]
《Evaluation of recording paper》
The following measurements and evaluations were performed on the recording sheets 1 to 15 produced as described above.
[0171]
(Measurement of glossiness)
The glossiness on the recording surface side was measured by using a glossmeter (VGS-1001DP) manufactured by Nippon Denshoku Industries Co., Ltd. to measure the glossiness at 60 degrees.
[0172]
(Measurement of C value)
The C value on the recording surface side was measured at a reflection of 60 degrees using an image clarity measuring device (ICM-1DP) manufactured by Suga Test Instruments Co., Ltd.
[0173]
(Evaluation of glossiness visually)
The glossiness on the recording surface side of each of the recording papers prepared above was determined as 1 point when the glossiness was good, 0.5 point when the glossiness was normal, and 0 point when the glossiness was inferior according to a general monitor of 10 persons. Then, a total score of 10 persons was obtained, and the glossiness was evaluated according to the following criteria.
[0174]
◎: Total score is 8 or more
：: Total score is 6 to 7.5 points
Δ: Total score is 3 to 5.5 points
X: The total score is 2.5 points or less.
(Scratch resistance: evaluation of the conspicuousness of scars)
All the papers were scratched with a metal piece at the same level of force, and the trace was visually confirmed.
[0175]
：: scar scarcely noticeable
×: The scar is clearly visible
(Measurement of maximum concentration)
Black solid printing was performed using an inkjet printer PM950C manufactured by Seiko Epson Corporation, and the maximum reflection density was measured with an optical densitometer (X-Rite938 manufactured by X-Rite).
[0176]
(Evaluation of high humidity bleed resistance)
A magenta solid image is printed on each recording paper by a Canon inkjet printer BJF850, and a black line having a line width of about 0.3 mm is printed thereon. Five sheets were stacked and stored for 7 days in an atmosphere of 50 ° C. and 85% relative humidity.
[0177]
For each sample processed as described above, the line width of the black line before and after storage was measured with a microdensitometer (the width of the portion where the reflection density was 50% of the maximum density was taken as the line width). The bleeding rate was determined according to the formula, and the bleeding resistance was determined according to the following evaluation criteria. The smaller the numerical value of the bleeding ratio, the better the bleeding resistance.
[0178]
Bleed rate = (line width after image storage) / (line width before image storage)
：: The bleeding rate is 1 to less than 1.2
：: The bleeding rate is 1.2 to less than 1.35.
Δ: Bleeding rate is less than 1.35 to 1.5
×: The bleeding rate is 1.5 or more
Table 1 shows the results obtained as described above.
[0179]
[Table 1]

[0180]
As is evident from Table 1, the recording paper of the present invention has a good glossiness visually before printing compared to the comparative recording paper, and has a high gloss without being noticeable after printing even if the surface is scratched before printing. It can be seen that high-density printing can be performed, and high-quality ink jet recording excellent in bleeding resistance can be obtained.
[0181]
【The invention's effect】
Advantageous Effects of Invention According to the present invention, high-density printing can be performed with good glossiness by visual inspection before printing and without noticeable after printing even if the surface is scratched before printing, and high image quality with excellent bleeding resistance Thus, an ink jet recording paper capable of obtaining a proper ink jet recording can be provided.

Claims (6)

In an ink jet recording sheet having at least one ink absorbing layer on a support, at least one surface of the support has a hydrophilic binder, a cationic compound, and inorganic fine particles having an average particle size of primary particles of 50 nm or less. A porous ink-absorbing layer made of the following. The surface of the porous ink-absorbing layer has a 60-degree specular glossiness defined by JIS Z8741 of 30% or more, and a surface defined by JIS K7105. An ink-jet recording sheet having a C value of 65 to 85%. The ink jet recording paper according to claim 1, wherein the support is a non-water-absorbing support. 3. The ink jet recording paper according to claim 1, wherein the inorganic fine particles are silica fine particles. The inkjet recording paper according to any one of claims 1 to 3, wherein at least one of the cationic compounds is a cationic polymer having a repeating unit represented by the following general formula (1). .

[In the formula, R represents a hydrogen atom or an alkyl group, R ₁ , R ₂ , and R ₃ each represent an alkyl group or a benzyl group, and J represents a simple bond or a divalent organic group. X ^- represents an anionic group. ] 5. The method according to claim 1, wherein at least one of the cationic compounds is a compound having a zirconium atom (excluding zirconium oxide) or a compound having an aluminum atom (excluding aluminum oxide). The inkjet recording paper according to any one of claims 1 to 7. The inkjet recording paper according to any one of claims 3 to 5, wherein the silica fine particles are fumed silica.