JP2004122709A - Inkjet recording paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording paper, which has a favorable ink absorbency, high color developing density, can make a high image quality recording realizing a photographic image quality possible and is excellent in storage stability, especially in gas fading properties. <P>SOLUTION: This inkjet recording paper has a porous ink accepting layer including a compound having a plurality of non-aromatic carbon-carbon unsaturated bonds in a molecule, an inorganic pigment and a hydrophilic binder under the condition that the opacity of the porous ink accepting layer is 1-20%. <P>COPYRIGHT: (C)2004,JPO

Description

【００８６】
【化２】

【００８７】
第４級アンモニウム塩基と共重合し得るモノマーはエチレン性不飽和基を有する化合物であり、例えば以下の具体例を挙げることが出来る。
【００８８】
【化３】

【００８９】
以下に本発明に好ましく用いられるカチオン性ポリマーの具体例を示すが、本発明はこれらに限定されるものではない。
【００９０】
【化４】

【００９１】
【化５】

【００９２】
【化６】

【００９３】
【化７】

【００９４】
特に第４級アンモニウム塩基を有するカチオン性ポリマーが共重合体である場合、カチオン性モノマーの比率は通常１０モル％以上、好ましくは２０モル％以上、特に好ましくは３０モル％以上である。
【００９５】
第４級アンモニウム塩基を有するモノマーは単一でも２種類以上であっても良い。
【００９６】
第４級アンモニウム塩基を有するカチオン性ポリマーは第４級アンモニウム塩基のために水溶性が一般に高いが、共重合する第４級アンモニウム塩基を含まないモノマーの組成や比率によっては水に充分に溶解しないことがあるが、水混和性有機溶媒と水との混合溶媒に溶解させることにより溶解し得るもので有れば本発明には使用できる。
【００９７】
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、水に対して通常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。
【００９８】
ここで質量平均分子量は、ゲルパーミエーションクロマトグラフィーから求められたポリエチレングリコール値に換算した値である。
【００９９】
カチオン性ポリマーの溶液を、表面アニオン性の微粒子含有分散液に添加する際、凝集物が激しく発生してしまうことがあり得るが、カチオン性ポリマーの質量平均分子量が１０万以下の場合にはこのような現象が起こりにくく、従って、粗大粒子をあまり含まない、ほぼ均一な分散液が得られ易い。このような分散液を使用して作製したインクジェット記録用紙には、優れた光沢性が期待できるのである。同様の観点から、上記質量平均分子量は５万以下であると更に好ましい。
【０１００】
質量平均分子量の下限は染料の耐水性の点から通常２０００以上である。
上記微粒子とカチオン性ポリマーの比率は、微粒子の種類や平均粒径又はカチオン性ポリマーの種類や質量平均分子量で変わり得ることができ、本発明においては、上記比率は微粒子の表面がカチオン性に置き換わって安定化させる為に、１：０．０１〜１：１であることが好ましい。
【０１０１】
上記の範囲であれば、微粒子のアニオン成分がカチオン成分によって完全に被覆されるので、微粒子のアニオン部分とカチオン性ポリマーのカチオン部分とがイオン結合して粗大な粒子を形成するようなおそれも生じない。
【０１０２】
カチオン性ポリマーの添加量は無機微粒子１に対して質量比で通常０．０１〜０．３であり、特に、０．０５〜０．２が好ましい。
【０１０３】
無機微粒子としては、表面がカチオン性であり染料定着性を有する無機微粒子が好ましい。表面がカチオン性である無機微粒子としては、カチオン表面処理された気相法シリカ、カチオン表面処理されたコロイダルシリカ、およびアルミナ、コロイダルアルミナ、擬ベーマイト等を用いることができる。
【０１０４】
また、本発明のインクジェット記録用紙は画像の耐水性や、耐湿性を改良するため、多価金属イオンを含有させることが好ましい。多価金属イオンは２価以上の金属イオンであれば特に限定されるものでは無いが、好ましい多価金属イオンとしては、アルミニウムイオン、ジルコニウムイオン、チタニウムイオン等が挙げられる。
【０１０５】
これらの多価金属イオンは、水溶性または非水溶性の塩の形態でインク受容層に含有させることができる。アルミニウムイオンを含む塩の具体例としては、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）、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）、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）、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）、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。
【０１０６】
これらの中でも、塩化アルミニウム、塩基性塩化アルミニウム、硫酸アルミニウム、塩基性硫酸アルミニウム、塩基性硫酸珪酸アルミニウムが好ましく、塩基性塩化アルミニウム、塩基性硫酸アルミニウムが最も好ましい。
【０１０７】
また、ジルコニウムイオンを含む塩の具体例としては、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（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等が挙げられる。
【０１０８】
これらの化合物の中でも、本発明の目的とするプリント後の滲み防止効果を更に顕著に奏するという観点において、炭酸ジルコニル、炭酸ジルコニルアンモニウム、酢酸ジルコニル、硝酸ジルコニル、酸塩化ジルコニル、乳酸ジルコニル、クエン酸ジルコニルが好ましく、特に、炭酸ジルコニルアンモニウム、酸塩化ジルコニル、酢酸ジルコニルが好ましい。
【０１０９】
これらの多価金属イオンは、単独で用いても良いし、異なる２種以上を併用してもよい。多価金属イオンを含む化合物は、インク受容層を形成する塗布液に添加してもよいし、あるいは多孔質インク受容層を一旦塗布乾燥した後、インク受容層にオーバーコート法により塗設してもよい。前者の多価金属イオンを含む化合物をインク受容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方法、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方法を用いることができる。インク受容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、また２層以上の層、あるいは全ての構成層の塗布液に添加することもできる。また、後者の多孔質インク受容層を一旦形成した後、オーバーコート法で添加する場合には、多価金属イオンを含む化合物を溶媒に均一に溶解した後、インク受容層に供給するのが好ましい。
【０１１０】
これらの多価金属イオンは、記録用紙１ｍ^２当り、概ね０．０５〜２０ミリモル、好ましくは０．１〜１０ミリモルの範囲で用いられる。
【０１１１】
本発明のインクジェット記録用紙は、多孔質空隙層を形成する親水性バインダーの硬化剤を添加することが好ましい。本発明で用いることのできる硬化剤としては、水溶性バインダーと硬化反応を起こすものであれば特に制限はないが、ホウ酸及びその塩が好ましいが、その他にも公知のものが使用でき、一般的には水溶性バインダーと反応し得る基を有する化合物あるいは水溶性バインダーが有する異なる基同士の反応を促進するような化合物であり、水溶性バインダーの種類に応じて適宜選択して用いられる。硬化剤の具体例としては、例えば、エポキシ系硬化剤（ジグリシジルエチルエーテル、エチレングリコールジグリシジルエーテル、１，４−ブタンジオールジグリシジルエーテル、１，６−ジグリシジルシクロヘキサン、Ｎ，Ｎ−ジグリシジル−４−グリシジルオキシアニリン、ソルビトールポリグリシジルエーテル、グリセロールポリグリシジルエーテル等）、アルデヒド系硬化剤（ホルムアルデヒド、グリオキザール等）、活性ハロゲン系硬化剤（２，４−ジクロロ−６−ヒドロキシ−ｓ−トリアジン等）、活性ビニル系化合物（１，３，５−トリスアクリロイル−ヘキサヒドロ−ｓ−トリアジン、ビスビニルスルホニルメチルエーテル等）、アルミニウム明礬等が挙げられる。
【０１１２】
ホウ酸またはその塩とは、硼素原子を中心原子とする酸素酸およびその塩のことをいい、具体的には、オルトホウ酸、二ホウ酸、メタホウ酸、四ホウ酸、五ホウ酸および八ホウ酸およびそれらの塩が挙げられる。
【０１１３】
硬化剤としてのホウ素原子を有するホウ酸およびその塩は、単独の水溶液でも、また、２種以上を混合して使用しても良い。特に好ましいのはホウ酸とホウ砂の混合水溶液である。
【０１１４】
ホウ酸とホウ砂の水溶液は、それぞれ比較的希薄水溶液でしか添加することが出来ないが両者を混合することで濃厚な水溶液にすることが出来、塗布液を濃縮化する事が出来る。また、添加する水溶液のｐＨを比較的自由にコントロールすることが出来る利点がある。
【０１１５】
上記硬化剤の総使用量は、上記水溶性バインダー１ｇ当たり１〜６００ｍｇが好ましい。
【０１１６】
本発明に用いる支持体は従来インクジェット記録用紙用として公知のものを適宜使用でき、吸水性支持体であってもよいが、非吸水性支持体であることが好ましい。
【０１１７】
本発明で用いることのできる吸水性支持体としては、例えば一般の紙、布、木材等を有するシートや板等を挙げることができるが、特に紙は基材自身の吸水性に優れかつコスト的にも優れるために最も好ましい。紙支持体としては、ＬＢＫＰ、ＮＢＫＰ等の化学パルプ、ＧＰ、ＣＧＰ、ＲＭＰ、ＴＭＰ、ＣＴＭＰ、ＣＭＰ、ＰＧＷ等の機械パルプ、ＤＩＰ等の古紙パルプ等の木材パルプを主原料としたものが使用可能である。又、必要に応じて合成パルプ、合成繊維、無機繊維等の各種繊維状物質も原料として適宜使用することができる。
【０１１８】
上記紙支持体中には必要に応じて、サイズ剤、顔料、紙力増強剤、定着剤等、蛍光増白剤、湿潤紙力剤、カチオン化剤等の従来公知の各種添加剤を添加することができる。
【０１１９】
紙支持体は前記の木材パルプなどの繊維状物質と各種添加剤を混合し、長網抄紙機、円網抄紙機、ツインワイヤー抄紙機等の各種抄紙機で製造することができる。又、必要に応じて抄紙段階または抄紙機にスターチ、ポリビニルアルコール等でサイズプレス処理したり、各種コート処理したり、カレンダー処理したりすることもできる。
【０１２０】
本発明で好ましく用いることのできる非吸水性支持体には、透明支持体または不透明支持体がある。透明支持体としてはポリエステル系樹脂、ジアセテート系樹脂、トリアテセート系樹脂、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を有するフィルム等が挙げられ、中でもＯＨＰとして使用されたときの輻射熱に耐える性質のものが好ましく、ポリエチレンテレフタレートが特に好ましい。このような透明な支持体の厚さとしては、５０μｍ〜２００μｍが好ましい。
【０１２１】
又不透明支持体としては、例えば、基紙の少なくとも一方に白色顔料等を添加したポリオレフィ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硫酸バリウム等の白色顔料を添加してなるいわゆるホワイトペットが好ましい。
【０１２２】
前記各種支持体とインク吸収層の接着強度を大きくする等の目的で、インク吸収層の塗布に先立って、支持体にコロナ放電処理や下引処理等を行うことが好ましい。更に、本発明のインクジェット記録用紙は必ずしも無色である必要はなく、着色された記録シートであってもよい。
【０１２３】
本発明のインクジェット記録用紙では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ために特に好ましい。そのようなポリエチレンでラミネートした紙支持体について以下に説明する。
【０１２４】
紙支持体に用いられる原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などの合成パルプ或いはナイロンやポリエステルなど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出来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。但し、ＬＢＳＰ及びまたはＬＤＰの比率は１０質量％〜７０質量％が好ましい。
【０１２５】
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、又、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。
【０１２６】
原紙中には、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、酸化チタンなどの白色顔料、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などを適宜添加することが出来る。
【０１２７】
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、又、叩解後の繊維長がＪＩＳ−Ｐ−８２０７に規定される２４メッシュ残分の質量％と４２メッシュ残分の質量％との和が３０〜７０％が好ましい。尚、４メッシュ残分の質量％は２０質量％以下であることが好ましい。
【０１２８】
原紙の坪量は３０〜２５０ｇが好ましく、特に５０〜２００ｇが好ましい。原紙の厚さは４０〜２５０μｍが好ましい。
【０１２９】
原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出来る。原紙密度は０．７〜１．２ｇ／ｃｍ^３（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。
【０１３０】
原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添加できるサイズと同様のサイズ剤を使用できる。
【０１３１】
原紙の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、５〜９であることが好ましい
原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出来る。
【０１３２】
特にインク吸収層側のポリエチレン層は写真用印画紙で広く行われているようにルチルまたはアナターゼ型の酸化チタンをポリエチレン中に添加し、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エチレンに対して通常３質量％〜２０質量％、好ましくは４質量％〜１３質量％である。
【０１３３】
ポリエチレン被覆紙は光沢紙として用いることも、又、ポリエチレンを原紙表面上に溶融押し出してコーティングする際にいわゆる型付け処理を行って通常の写真印画紙で得られるようなマット面や絹目面を形成したものも本発明で使用できる。
【０１３４】
上記ポリエチレン被覆紙においては紙中の含水率を３質量％〜１０質量％に保持するのが特に好ましい。
【０１３５】
本発明のインクジェット記録媒体には、各種の添加剤を添加することが出来る。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、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、同５７−８７９８８号及び同６２−２６１４７６号に記載の紫外線吸収剤、特開昭５７−７４１９２号、同５７−８７９８９号、同６０−７２７８５号、同６１−１４６５９１号、特開平１−９５０９１号及び同３−１３３７６号等に記載されている退色防止剤、特開昭５９−４２９９３号、同５９−５２６８９号、同６２−２８００６９号、同６１−２４２８７１号及び特開平４−２１９２６６号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。
【０１３６】
インクジェット記録媒体の製造方法としては、インク吸収層を含む各構成層を、各々単独にあるいは同時に、公知の塗布方式から適宜選択して、支持体上に塗布、乾燥して製造することができる。塗布方式としては、例えば、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２，７６１，４１９号、同第２，７６１，７９１号公報に記載のホッパーを使用するスライドビード塗布方法、エクストルージョンコート法等が好ましく用いられる。
【０１３７】
同時重層塗布を行う際の各塗布液の粘度としては、スライドビード塗布方式を用いる場合には、５〜１００ｍＰａ・ｓの範囲が好ましく、さらに好ましくは１０〜５０ｍＰａ・ｓの範囲である。また、カーテン塗布方式を用いる場合には、５〜１２００ｍＰａ・ｓの範囲が好ましく、さらに好ましくは２５〜５００ｍＰａ・ｓの範囲である。
【０１３８】
また、塗布液の１５℃における粘度としては、１００ｍＰａ・ｓ以上が好ましく、１００〜３０，０００ｍＰａ・ｓがより好ましく、さらに好ましくは３，０００〜３０，０００ｍＰａ・ｓであり、最も好ましいのは１０，０００〜３０，０００ｍＰａ・ｓである。
【０１３９】
塗布および乾燥方法としては、塗布液を３０℃以上に加温して、同時重層塗布を行った後、形成した塗膜の温度を１〜１５℃に一旦冷却し、１０℃以上で乾燥することが好ましい。塗布液調製時、塗布時及び乾燥時おいて、表層に含まれる熱可塑性樹脂が製膜しないように、該熱可塑性樹脂のＴｇ以下の温度で塗布液の調製、塗布、乾燥することが好ましい。より好ましくは、乾燥条件として、湿球温度５〜５０℃、膜面温度１０〜５０℃の範囲の条件で行うことである。また、塗布直後の冷却方式としては、形成された塗膜均一性の観点から、水平セット方式で行うことが好ましい。
【０１４０】
また、その製造過程で３５℃以上、７０℃以下の条件で２４時間以上、６０日以下保存する工程を有することが好ましい。
【０１４１】
加温条件は、３５℃以上、７０℃以下の条件で２４時間以上、６０日以下保存する条件であれば特に制限はないが、好ましい例としては、例えば、３６℃で３日〜４週間、４０℃で２日〜２週間、あるいは５５℃で１〜７日間である。この熱処理を施すことにより、水溶性バインダーの硬化反応の促進、あるいは水溶性バインダーの結晶化を促進することができ、その結果、好ましいインク吸収性を達成することができる。
【０１４２】
【実施例】
以下、本発明の実施例を挙げて説明するが、本発明はこれらの例に限定されるものではない。なお、実施例中で「％」は、特に断りの無いかぎり質量％を表す。
【０１４３】
実施例１
シリカ分散液Ｄ−１の調製
予め均一に分散されている、１次粒子の平均粒径が約０．００７μｍの気相法シリカ（日本アエロジル社製；アエロジル３００）を２５％含むシリカ分散液Ｂ−１（ｐＨ２．６、エタノール０．５％含有）の４００Ｌを、カチオン性ポリマーＰ−１を１２％、ｎ−プロパノールを１０％およびエタノールを２％含有する水溶液Ｃ−１（ｐＨ２．５、サンノプコ社製の消泡剤ＳＮ−３８１を２ｇ含有）の１１０Ｌに、室温で３０００ｒｐｍで攪拌しながら添加した。次いで硼酸とホウ砂の１：１質量比の混合水溶液Ａ−１（各々３％の濃度）５４Ｌを攪拌しながら、徐々に添加した。
【０１４４】
次いで、三和工業株式会社製の高圧ホモジナイザーで３０００Ｎ／ｃｍ^２の圧力で分散し、全量を純水で６３０Ｌに仕上げて、ほぼ透明なシリカ分散液Ｄ−１を得た。
【０１４５】
シリカ分散液Ｄ−２の調製
上記シリカ分散液Ｂ−１の４００Ｌを、カチオン性ポリマーＰ−２を１２％、ｎ−プロパノール１０％およびエタノールを２％含有する水溶液Ｃ−２（ｐＨ＝２．５）の１２０Ｌに、室温で３０００ｒｐｍで攪拌しながら添加し、次いで、上記混合水溶液Ａ−１の５２Ｌを攪拌しながら徐々に添加した。次いで、三和工業株式会社製の高圧ホモジナイザーで、３０００Ｎ／ｃｍ^２の圧力で分散し、全量を純水で６３０Ｌに仕上げて、ほぼ透明なシリカ分散液Ｄ−２を得た。
【０１４６】
上記シリカ分散液Ｄ−１、Ｄ−２を３０μｍの濾過精度を有するアドバンテック東洋社製のＴＣＰ−３０タイプのフィルターを用いて濾過を行った。
【０１４７】
オイル分散液の調製
ジイソデシルフタレート２０ｋｇと酸化防止剤（ＡＯ−１）２０ｋｇとを４５ｋｇの酢酸エチルに加熱溶解し、酸処理ゼラチン８ｋｇ、カチオン製ポリマーＰ−１を２．９ｋｇおよびサポニン５ｋｇとを含有するゼラチン水溶液２１０Ｌと５５℃で混合し、高圧ホモジナイザーで乳化分散した後、全量を純水で３００Ｌに仕上げて、オイル分散液を調製した。
【０１４８】
【化８】

【０１４９】
塗布液の調製
上記調製した各分散液を使用して、以下に記載の各添加剤を順次混合して、多孔質インク受容層用の各塗布液を調製した。なお、各添加量は塗布液１Ｌ当りの量で表示した。
【０１５０】
（第１層用塗布液；最下層）
シリカ分散液Ｄ−１　　　　　　　　　　　　　　　　　　　　　５８０ｍｌ
ポリビニルアルコール（クラレ社製；ＰＶＡ２０３）１０％水溶液　　５ｍｌ
ポリビニルアルコール（平均重合度：３８００　ケン化度８８％）５％水溶液
２９０ｍｌ
オイル分散液　　　　　　　　　　　　　　　　　　　　　　　　　３０ｍｌ
ラテックス分散液（昭和高分子社製　ＡＥ−８０３）　　　　　　　４２ｍｌ
エタノール　　　　　　　　　　　　　　　　　　　　　　　　　８．５ｍｌ
純水で全量を１０００ｍｌに仕上げる。
【０１５１】
（第２層用塗布液）
シリカ分散液Ｄ−１　　　　　　　　　　　　　　　　　　　　　５８０ｍｌ
ポリビニルアルコール（クラレ社製；ＰＶＡ２０３）１０％水溶液　　５ｍｌ
ポリビニルアルコール（平均重合度：３８００　ケン化度８８％）５％水溶液
２７０ｍｌ
オイル分散液　　　　　　　　　　　　　　　　　　　　　　　　　２０ｍｌ
ラテックス分散液（昭和高分子社製　ＡＥ−８０３）　　　　　　　２２ｍｌ
エタノール　　　　　　　　　　　　　　　　　　　　　　　　　　　８ｍｌ
純水で全量を１０００ｍｌに仕上げる。
【０１５２】
（第３層用塗布液）
シリカ分散液Ｄ−２　　　　　　　　　　　　　　　　　　　　　６３０ｍｌ
ポリビニルアルコール（クラレ社製；ＰＶＡ２０３）１０％水溶液　　５ｍｌ
ポリビニルアルコール（平均重合度：３８００　ケン化度８８％）５％水溶液
２７０ｍｌ
オイル分散液　　　　　　　　　　　　　　　　　　　　　　　　　１０ｍｌ
ラテックス分散液（昭和高分子社製　ＡＥ−８０３　　　　　　　　　５ｍｌ
エタノール　　　　　　　　　　　　　　　　　　　　　　　　　　　３ｍｌ
純水で全量を１０００ｍｌに仕上げる。
【０１５３】
（第４層用塗布液；最上層）
シリカ分散液Ｄ−２　　　　　　　　　　　　　　　　　　　　　６６０ｍｌ
ポリビニルアルコール（クラレ社製；ＰＶＡ２０３）１０％水溶液　　５ｍｌ
ポリビニルアルコール平均重合度：３８００　ケン化度８８％）５％水溶液２５０ｍｌ
カチオン型界面活性剤−１の４％水溶液　　　　　　　　　　　　　　３ｍｌ
サポニンの２５％水溶液　　　　　　　　　　　　　　　　　　　　　２ｍｌ
エタノール　　　　　　　　　　　　　　　　　　　　　　　　　　　３ｍｌ
純水で全量を１０００ｍｌに仕上げる。
【０１５４】
【化９】

【０１５５】
上記の様に調製した各塗布液を、２０μｍの濾過精度を持つアドバンテック東洋社製のＴＣＰＤ−３０フィルターで濾過した後、ＴＣＰＤ−１０フィルターで濾過した。
【０１５６】
記録用紙−１の作製
次に、上記の各塗布液を下記に記載の湿潤膜厚となるよう、４０℃で両面にポリエチレンを被覆した紙支持体上に、スライドホッパー型コーターを用いて４層同時塗布した。
【０１５７】
＜湿潤膜厚＞
第１層：４２μｍ
第２層：３９μｍ
第３層；４４μｍ
第４層：３８μｍ
なお、上記紙支持体は幅が約１．５ｍ、長さが約４０００ｍのロール状に巻かれた下記の支持体を用いた。
【０１５８】
使用した紙支持体は、含水率が８％で、坪量が１７０ｇの写真用原紙表面を、アナターゼ型酸化チタンを６％含有するポリエチレンを厚さ３５μｍで押し出し溶融塗布し、裏面には厚さ４０μｍのポリエチレンを厚さ３５μｍで押し出し溶融塗布した。表面側はコロナ放電した後、ポリビニルアルコール（クラレ社製　ＰＶＡ２３５）を記録媒体１ｍ^２当り０．０５ｇになるように下引き層を塗布し、裏面側にはコロナ放電した後、Ｔｇが約８０℃のスチレン−アクリル酸エステル系ラテックスバインダー約０．４ｇ、帯電防止剤（カチオン性ポリマー）０．１ｇおよび約２μｍのシリカ０．１ｇをマット剤として含有するバック層を塗布した。
【０１５９】
インク受容層塗布液の塗布後の乾燥は、５℃に保った冷却ゾーンを１５秒間通過させて膜面の温度を１３℃にまで低下させた後、複数設けた乾燥ゾーンの温度を適宜設定して乾燥を行った後、ロール状に巻き取って比較の記録用紙−１を得た。
【０１６０】
記録用紙−２の作製
記録用紙−１にＰｏｌｙ　ｂｄ　Ｒ４５ＨＴ（出光石油化学（株）製；数平均分子量　２，８００）の酢酸エチル５％溶液を１ｍ^２あたり２０ｍｌオーバーコートにより含浸させ記録用紙−２を作製した。
【０１６１】
記録用紙−３の作製
記録用紙−２の作製に用いたＰｏｌｙ　ｂｄ　Ｒ４５ＨＴをＰｏｌｙ　ｂｄ　Ｒ１５ＨＴ（出光石油化学（株）製；数平均分子量１，２００）に代えた以外は記録用紙−２と同様にして記録用紙−３を作製した。
【０１６２】
記録用紙−４の作製
記録用紙−２の作製に用いたＰｏｌｙ　ｂｄ　Ｒ４５ＨＴをＰｏｌｙ　ｏｉｌ１３０（日本ゼオン（株）製；数平均分子量３，０００）に代えた以外は記録用紙−２と同様にして記録用紙−４を作製した。
【０１６３】
記録用紙−５の作製
記録用紙−２の作製に用いたＰｏｌｙ　ｂｄ　Ｒ４５ＨＴをＮｉｓｓｏ　ＰＢＢ−１０００（日本曹達（株）製；数平均分子量９００〜１，３００）に代えた以外は記録用紙−２と同様にして記録用紙−５を作製した。
【０１６４】
記録用紙−６の作製
記録用紙−２の作製に用いたＰｏｌｙ　ｂｄ　Ｒ４５ＨＴをダイソーダップＳ（ダイソー（株）製ポリアリルフタレート；平均分子量３５，０００）に代えた以外は記録用紙−２と同様にして記録用紙−６を作製した。
【０１６５】
記録用紙−７の作製
記録用紙−４の作製において、シリカ分散液Ｂ−１の調製に用いた気相法シリカをアエロジル９０Ｇ（日本アエロジル社製；平均一次粒径２０ｎｍ）に代えてそのまま、シリカ分散液Ｄ−１およびシリカ分散液Ｄ−２の調製を行った以外は、記録用紙−４と同様にして、記録用紙−７を作製した。
【０１６６】
記録用紙−８〜１２の作製
記録用紙−７の作製において、各層の塗布液に表１に記載したように、有機微粒子を添加した以外は、記録用紙−１と同様にして記録用紙８〜１２を作製した。
【０１６７】
【表１】

【０１６８】
記録用紙−１３の作製
ジルコゾールＺＡ（第一稀元素化学工業（株）製；酢酸ジルコニル水溶液）を純水で希釈し、スプレー塗布を行い記録用紙−３に酢酸ジルコニルの付き量が０．５ｇ／ｍ^２になるように均一に塗布した後乾燥し、記録用紙−１３を作製した。
【０１６９】
以上のようにして得られたインクジェット記録用紙−１〜１３についてそれぞれ以下の項目の評価を行った。
【０１７０】
（画像保存性）
上記のようにして得られた記録用紙をキヤノン株式会社製ＢＪ−Ｆ８７０を用い、シアンのベタ画像を記録した後、外気を直接プリント画像に１ケ月間吹き付けてシアン画像のガス褪色性を評価した。褪色性は初期濃度の残存率で示した。
【０１７１】
（まだら性（斑））
キヤノン製インクジェットプリンタＢＪＦ８７０にて緑のベタをプリントして、その均一性を目視評価した。
◎；全く均一なベタ画像である
○；観察距離３０ｃｍ以上で均一に感じられる
△；観察距離６０ｃｍ以上で均一に感じられる
×；観察距離６０ｃｍ以上でもまだらに感じられる。
【０１７２】
（最高濃度）
セイコーエプソン社製インクジェットプリンタＰＭ９００Ｃにて黒のベタをプリントして、反射濃度を測定した。
【０１７３】
（ひび割れ）
塗布面を目視で観察し、ひび割れ状態を以下の基準で評価した。
◎；ひび割れがほとんど観察されない
○；０．５ｍｍ未満の微小なひび割れが数点観察される
△；０．５ｍｍ以上の粗大なひび割れが数点観察される
×；０．５ｍｍ以上の粗大なひび割れが全面に観察される。
【０１７４】
（にじみ）
セイコーエプソン社製インクジェットプリンタＰＭ９００Ｃにてマゼンタの細線（幅１／３００×２．５４ｃｍ）をプリントし、２３℃、８０％ＲＨの環境に一週間放置して、細線の線幅の増大率を求めた。
【０１７５】
（不透明度）
インク受容層の不透明度は実施例、比較例で使用した塗布液をポリエチレンフィルムにそれぞれ同様の方法で塗布、乾燥後、ＪＩＳ−Ｐ−８１３８に基づき、ハンター式比色光度計（東洋精機製）により測定した。すべての評価結果を表２に示す
【０１７６】
【表２】

【０１７７】
表２から本発明によるインクジェット記録用紙は、画像保存性を改良し、濃度が高く、ひび割れ、にじみ、まだらのない優れた画像が得られる。
【０１７８】
【発明の効果】
本発明により、インク吸収性が良好で、発色濃度が高く、写真画質を達成した高画質の記録が可能で、保存安定性特にガス褪色性に優れた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 sheet, and more particularly, to an ink jet recording sheet having good ink absorbency, high maximum density, high quality image recording, and excellent storage stability.
[0002]
[Prior art]
In recent years, the image quality of ink jet recording materials has been rapidly improved, and the quality of photographs is approaching. In particular, in order to achieve image quality comparable to photographic image quality in ink jet recording, improvements have been made in terms of ink jet recording paper (hereinafter, also simply referred to as recording paper), and fine particles are formed on a highly smooth support. A void-type recording paper provided with a microporous layer made of a hydrophilic polymer has a high gloss, shows vivid coloration, and is excellent in ink absorption and drying properties, so that it is closest to photographic quality. It is becoming one of the things. In particular, when a non-water-absorbing support is used, cockling after printing as seen in the water-absorbing support does not occur, so-called `` wrinkles '' do not occur, and a highly smooth surface can be maintained. You can get a print.
[0003]
Ink jet recording is generally divided into those using water-based inks using water and water-soluble solvents as ink solvents and those using non-aqueous oil-based solvents, each of which uses a dye as a coloring material and a type using a pigment. In order to obtain a high-quality recorded image, dedicated paper suitable for each type is required. With respect to inks, water-based inks, which have a small environmental and safety load, are mainly used.
[0004]
Among the water-based inks, the pigment ink has high durability of the image, but the gloss tends to change in an image form, and as a result, it is difficult to obtain a print close to the photographic quality. A color print comparable to photographic image quality having high sharpness and uniform surface gloss can be obtained.
[0005]
However, while this water-soluble dye provides a high-quality image, it has poor storage stability as compared with pigments, and is largely discolored by sunlight or indoor light, and discolored by oxidizing gas such as ozone present in the air. That is a challenge. In particular, in the case of a void-type recording paper provided with a fine porous layer, the contact area between the dye and the room air becomes large, so that the recording paper is easily affected by the oxidizing gas in the air, and improvement is desired.
[0006]
In order to improve such deterioration due to storage, many methods of adding various compounds have been conventionally proposed as a method for preventing fading.
[0007]
For example, inkjet recording paper containing various compounds as antioxidants (see Patent Documents 1 to 3), inkjet recording paper containing an ultraviolet absorber (see Patent Document 4), and hydrazides are added (Patent Document 5). ), Add a hindered amine-based antioxidant (see Patent Document 6), add a nitrogen-containing heterocyclic mercapto-based compound (see Patent Document 7), and add a thioether-based antioxidant (see Patent Documents 8 and 9). ), Adding a hindered phenol-based antioxidant having a specific structure (see Patent Document 10), adding a hindered phenol-based antioxidant and a hindered amine-based antioxidant in combination (see Patent Document 11), and adding ascorbic acids (See Patent Documents 12 and 13), zinc sulfate (see Patent Document 14), and thiocyanates. (See Patent Document 15), adding a thiourea derivative or the like (see Patent Document 16), adding a saccharide (see Patent Documents 17 and 18), and adding a phosphate antioxidant (see Patent Document 19). ), Adding nitrite, sulfite, thiosulfate and the like (see Patent Document 20), adding a hydroxylamine derivative (see Patent Document 21), and the like.
[0008]
However, the effect is not always sufficient in ink jet recording paper having fine voids, and when a large amount of such a compound is added in order to obtain a sufficient anti-fading effect, the pores themselves block the pores and become porous. There has been a problem that the ink absorption of the ink receiving layer (also referred to as an ink receiving layer) is reduced.
[0009]
In particular, problems when using a water-soluble dye ink include weak points such as bleeding and poor water resistance due to the high hydrophilicity of the dye. That is, the dye tends to bleed when stored for a long time under high humidity after recording or when water droplets adhere to the print surface. In order to solve this problem, it is common practice to add a dye fixing substance such as a cationic substance to the porous ink receiving layer. For example, a method in which a cationic polymer is combined with an anionic ink dye and immobilized firmly is preferably used. Examples of such a cationic polymer include a polymer having a quaternary ammonium group (see Patent Document 22) (see Non-Patent Document 1). There has also been proposed a method in which a water-soluble polyvalent metal ion is previously added to an ink jet recording sheet to immobilize and fix a dye during ink jet recording by immobilization. Although the use of a cationic polymer and a polyvalent metal ion improves bleeding and water resistance, the dye is unevenly dyed in the ink receiving layer due to the bonding with the cationic polymer and the polyvalent metal. Therefore, even if the above-mentioned compound for preventing discoloration is added, the effect may not be sufficiently exhibited if the compound has low diffusivity in the ink receiving layer.
[0010]
On the other hand, it is conventionally known that a resin having an unsaturated bond in a molecule such as butadiene rubber can be used for ink jet recording paper. For example, a method of using a resin mainly absorbing oily ink as a resin (see Patent Documents 23 to 29) is disclosed. Also disclosed is a method of using a diene polymer or a hydrogenated product thereof by sulfonating and hydrophilizing the diene polymer to improve the absorbability of the aqueous ink. It also discloses that a styrene-butadiene latex containing 20 to 45% of a butadiene component can be used as a binder to improve the storage stability in combination with a specific dye. The ratio was low and the effect was limited. When latex is added to the porous ink receiving layer, if the latex having an average particle diameter of 100 nm or more is used for the uppermost layer, devitrification of the ink receiving layer is caused, and the maximum density is reduced at the time of printing. Has a problem that it is difficult to obtain the image.
[0011]
[Patent Document 1]
JP-A-57-87989 (page 2, lower left column, line 17 to lower right column, line 7)
[0012]
[Patent Document 2]
JP-A-57-74192 (page 16, lower left column, line 16 to lower right column, second line, page 7, upper left column, line 1 to page 11, lower left column, first line)
[0013]
[Patent Document 3]
JP-A-60-72785 (page 15, lower left column, line 15 to page 4, lower right column, line 8)
[0014]
[Patent Document 4]
JP-A-57-74193 (page 3, upper left column, line 3 to line 10, page 9, upper right column, line 1 to page 11, lower right column, line 7)
[0015]
[Patent Document 5]
JP-A-61-1549989 (page 14, lower right column, line 14 to page 3, lower left column, line 18)
[0016]
[Patent Document 6]
JP-A-61-146591 (page 14, lower right column, line 14 to page 4, upper left column, line 6)
[0017]
[Patent Document 7]
JP-A-61-177279 (page 3, upper right column, second line to lower right column, fifth line)
[0018]
[Patent Document 8]
JP-A-1-115677 (page 3, upper right column, line 6 to page 4, upper left column, line 4)
[0019]
[Patent Document 9]
JP-A-1-36479 (page 6, upper left column, line 6 to upper right column, line 9)
[0020]
[Patent Document 10]
JP-A-1-36480 (page 2, upper left column, line 5 to upper right column, line 3)
[0021]
[Patent Document 11]
JP-A-3-13376 (page 13, upper right column, line 13 to page 5, lower left column, line 7)
[0022]
[Patent Document 12]
JP-A-7-195824 (page 2, right column, line 5 to page 3, left column, line 49)
[0023]
[Patent Document 13]
JP-A-8-150773 (page 3, left column, line 24 to page 4, left column, line 18)
[0024]
[Patent Document 14]
JP-A-7-149037 (page 8, right column, line 8 to page 3, left column, line 24)
[0025]
[Patent Document 15]
JP-A-7-314882 (page 2, left column, line 48 to page 3, left column, line 32)
[0026]
[Patent Document 16]
JP-A-7-314883 (Page 2, left column, line 41 to right column, line 28, page 3 left column, line 43 to right column, line 4)
[0027]
[Patent Document 17]
JP-A-7-276790 (page 37, left column, line 37 to page 5, right column, line 37)
[0028]
[Patent Document 18]
JP-A-8-108617 (page 19, right column, line 19 to page 3, right column, line 23)
[0029]
[Patent Document 19]
JP-A-8-118791 (page 11, right column, line 11 to page 6, left, line 24)
[0030]
[Patent Document 20]
JP-A-8-300807 (page 3, right column, lines 14 to 43)
[0031]
[Patent Document 21]
JP-A-9-267544 (page 3, left column, third line to page 5, right column, second line)
[0032]
[Patent Document 22]
JP-A-9-193532 (paragraph number [0008])
[0033]
[Patent Document 23]
JP-A-2000-177234 (paragraph numbers [0006] to [0007])
[0034]
[Patent Document 24]
JP 2000-238407 A (Paragraph numbers [0006] to [0008])
[0035]
[Patent Document 25]
JP 2001-205929 A (paragraph numbers [0011] to [0023])
[0036]
[Patent Document 26]
JP-A-11-165460 (paragraph numbers [0012] to [0024])
[0037]
[Patent Document 27]
JP-A-11-99742 (paragraph numbers [0007] to [0013])
[0038]
[Patent Document 28]
WO 2000/41890 pamphlet
[Patent Document 29]
WO 2000/41890 pamphlet
[Non-patent document 1]
"Inkjet Printer Technology and Materials" (CMC Co., Ltd., July 1998: 268-269)
[0041]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide an ink jet recording paper which has good ink absorbability, high color density, enables high-quality recording achieving photographic quality, and has excellent storage stability, especially gas fading. It is in.
[0042]
[Means for Solving the Problems]
The above object of the present invention has been achieved by the following configurations.
[0043]
1. A porous ink receiving layer containing a compound containing a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule, an inorganic pigment and a hydrophilic binder, wherein the opacity of the porous ink receiving layer is 1 to 20% of an inkjet recording paper.
[0044]
2. 2. The inkjet recording according to the item 1, wherein the compound containing a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule is a polymer or a copolymer obtained using butadiene as a monomer. Paper.
[0045]
3. 3. The ink jet recording paper according to the above item 1 or 2, wherein the compound containing a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule is polybutadiene having a number average molecular weight of 10,000 or less.
[0046]
4. The porous ink receiving layer comprises silica particles having an average primary particle diameter of 3 to 30 nm and a hydrophilic binder, and the silica particles are 2 to 20 times in mass ratio to the hydrophilic binder. The inkjet recording paper according to any one of claims 1 to 3.
[0047]
5. 5. The ink jet recording paper according to any one of the items 1 to 4, wherein the porous ink receiving layer contains a cationic resin. A porous ink receiving layer containing silica particles having an average primary particle size of 3 to 30 nm and a hydrophilic binder and having a silica particle mass ratio of 2 to 20 times the hydrophilic binder is added to a diene having a number average molecular weight of 10,000 or less. 6. The ink jet recording paper according to any one of the above items 1 to 5, which is overcoated with a polymer solution containing a system monomer in a constitutional unit.
[0048]
7. 7. An ink jet recording sheet according to any one of the above 1 to 6, wherein the ink jet recording sheet is for an aqueous dye ink.
[0049]
The present invention will be described in more detail. The ink jet recording paper of the present invention has a porous layer ink-receiving layer containing a compound containing a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule and an inorganic pigment, and the porous ink-receiving layer By setting the opacity to 1 to 20%, the preservability of the dye is improved, and the fading of the water-based dye ink due to the oxidizing gas, particularly the ozone gas, which has been a problem in the porous ink receiving layer, is remarkably improved. Thus, high-quality recording with high print density has become possible. It is not clear why the storage stability has been improved, but it is presumed that the carbon-carbon unsaturated bond has an appropriate reactivity with the oxidizing gas in the room and prevents the dye from fading. For example, it is known that the deterioration of a rubber-based resin proceeds with an unsaturated bond in the resin as a reactive group and is caused by oxygen, ozone, radicals, and peroxides. In order to prevent this rubber deterioration, hindered phenols, amines, sulfur compounds, and phosphorus compounds are used as antioxidants. These antioxidants have been applied to inkjet recording paper as dye fading inhibitors as described in the prior art. However, these antioxidants have a higher reactivity than the unsaturated bond of the rubber-based resin, which is considered to be highly reactive, and are used as a resin deterioration inhibitor. It is presumed that a void-type ink jet recording paper having minute voids, which are particularly susceptible to the influence, in the ink receiving layer, is consumed quickly and is unlikely to obtain a sustained effect. Unsaturated bonds, such as those inherent in rubber-based resins, are more reactive to oxidizing gases than dyes and have an anti-fading effect, but are more stable than the antioxidants described above, and therefore have a longer lasting effect. It is estimated that it has a higher anti-fading ability.
[0050]
Further, the opacity of the ink receiving layer of the recording paper of the present invention according to JIS-P8138 is 1 to 20%, the image density is hardly reduced due to the devitrification of the ink receiving layer, and high quality recording is possible. .
[0051]
The recording paper of the present invention is suitably used as a recording paper of a water-based dye ink. The water-based dye ink is an ink using a water-soluble dye or a water-dispersible dye as a coloring material, and is an ink obtained by mixing water or an organic solvent highly miscible with water as an ink solvent. Examples of the dyes include conventionally known azo dyes, xanthene dyes, phthalocyanine dyes, quinone dyes, anthraquinone dyes, and the like. Sex dyes are typically used. Further, an aqueous disperse dye ink in which a low water-soluble disperse dye is stably dispersed in an aqueous solvent can be used. As the ink solvent, water or an organic solvent having high miscibility with water can be used alone or as a mixture with water. Specifically, alcohol solvents such as ethanol, 2-propanol, ethylene glycol, propylene glycol, glycerin, 1,2-hexanediol, 1,6-hexanediol, diethylene glycol monomethyl ether, and tetraethylene glycol monomethyl ether; Amides such as pyrrolidinone, N-methylpyrrolidone, N, N-dimethylacetamide; amines such as triethanolamine, N-ethylmorpholine and triethylenetetramine; sulfolane, dimethylsulfoxide, urea, acetonitrile, acetone and the like; These solvents may be used alone or in combination.
[0052]
The ink jet recording paper of the present invention is obtained by applying a water-soluble coating solution for forming a porous ink receiving layer containing a hydrophilic binder and an inorganic pigment on a support to form a porous ink receiving layer having voids. is there. The porous ink receiving layer according to the present invention is mainly formed from fine particles and a hydrophilic binder. As the fine particles for forming the porous ink receiving layer, inorganic pigments and organic pigments can be used.Inorganic pigments are used because high gloss and high color density are obtained, and fine pigments are easily obtained. You. Examples of such inorganic pigments 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, hydrocarbon. White inorganic pigments such as talcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, and magnesium hydroxide. be able to. The inorganic pigment can be used as it is as primary particles, or can be used in a state where secondary aggregated particles are formed.
[0053]
In the present invention, from the viewpoint of obtaining high-quality prints on inkjet recording paper, silica or alumina is preferable as the inorganic pigment, and silica is more preferable.Furthermore, alumina, pseudoboehmite, colloidal silica or synthesized by a gas phase method. Fine particle silica is preferable, and fine particle silica synthesized by a gas phase method is particularly preferable. The silica synthesized by the gas phase method may have a surface modified with aluminum. The aluminum content of fumed silica whose surface is modified with aluminum is preferably 0.05 to 5% by mass relative to silica.
[0054]
Any particle diameter can be used for the inorganic pigment, but the average particle diameter is preferably 1 μm or less. If it is 1 μm or less, the opacity of the ink receiving layer is low, and the color developability is good. In this respect, silica particles of 200 nm or less are preferred. Further, silica of 100 nm or less is most preferable. The lower limit of the particle size is not particularly limited, but is preferably about 3 nm or more, particularly preferably 5 nm or more, and more preferably 20 nm or more, from the viewpoint of production of the inorganic pigment.
[0055]
The average particle size of the inorganic pigment is determined by observing the cross section and surface of the porous ink receiving layer with an electron microscope, determining the particle size of 100 arbitrary particles, and calculating the simple average value (number average). Here, each particle size is represented by a diameter assuming a circle equal to the projected area.
[0056]
The fine particles may be present in the porous film as primary particles or as secondary particles or higher-order aggregated particles. It refers to the particle size of what forms independent particles in the receiving layer.
[0057]
The average primary particle size of the fine particles must be equal to or less than the average particle size observed in the porous film, and the primary particle size of the fine particles is preferably 100 nm or less, more preferably 30 nm or less, and most preferably 30 nm or less. Preferably, they are fine particles of 4 to 20 nm.
[0058]
The content of the pigment in the water-soluble coating solution is 5 to 40% by mass, and particularly preferably 7 to 30% by mass. The pigment may have sufficient ink absorbency, it is necessary to form an ink absorbing layer cracks is small of the coating, the ink receiving layer is preferably formed on the amount per of 5 to 50 g / m ^2. Furthermore, it is particularly preferable that the amount be 10 to 25 g / m ² .
[0059]
The hydrophilic binder contained in the porous ink receiving layer is not particularly limited, and a conventionally known hydrophilic binder can be used. For example, gelatin, polyvinylpyrrolidone, polyethylene oxide, polyacrylamide, polyvinyl alcohol, or the like may be used. However, polyvinyl alcohol is particularly preferred.
[0060]
Polyvinyl alcohol has an interaction with an inorganic pigment, has a particularly high holding power to the inorganic pigment, is a polymer having a relatively small humidity dependency in hygroscopicity, and has a relatively small shrinkage stress during coating and drying. Excellent suitability for cracking during coating and drying. As the polyvinyl alcohol preferably used in the present invention, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, modified polyvinyl such as anion-modified polyvinyl alcohol having an anionic group or a polyvinyl alcohol having a cation-modified terminal. Also includes alcohol.
[0061]
The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 300 or more, and particularly preferably has an average degree of polymerization of 1,000 to 5,000. The saponification degree is preferably from 70 to 100%, particularly preferably from 80 to 99.8%.
[0062]
Examples of the cation-modified polyvinyl alcohol include, for example, a polyvinyl alcohol having a primary to tertiary amino group or a quaternary amino group in the main chain or side chain of the polyvinyl alcohol as described in JP-A-61-10483. Alcohols, which are obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.
[0063]
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, Examples include N-vinylimidazole, N-methylvinylimidazole, N- (3-dimethylaminopropyl) methacrylamide, hydroxyethyltrimethylammonium chloride, and trimethyl- (3-methacrylamidopropyl) ammonium chloride.
[0064]
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.
[0065]
Examples of the anion-modified polyvinyl alcohol include polyvinyl alcohol having an anionic group described in JP-A No. 1-2060888, and vinyl alcohol described in JP-A Nos. 61-237681 and 63-307979. Examples thereof include a copolymer with a vinyl compound having a water-soluble group, and a modified polyvinyl alcohol having a water-soluble group described in JP-A-7-285265.
[0066]
Further, as nonionic modified polyvinyl alcohol, for example, a polyvinyl alcohol derivative in which a polyalkylene oxide group is added to a part of vinyl alcohol described in JP-A-7-9758, and described in JP-A-8-25795 And a block copolymer of a vinyl compound having a hydrophobic group and vinyl alcohol.
[0067]
Two or more kinds of polyvinyl alcohols having different degrees of polymerization and different types of modification can be used in combination. In particular, when polyvinyl alcohol having a degree of polymerization of 2,000 or more is used, 0.05 to 10% by mass, preferably 0.1 to 5% by mass is added to the inorganic pigment in advance, and then the degree of polymerization is 2,000 or more. The addition of polyvinyl alcohol is preferable because there is no significant thickening.
[0068]
The ratio of the inorganic pigment to the hydrophilic binder in the porous ink receiving layer is preferably 2 to 20 by mass. When the mass ratio is 2 times or more, a porous film having a sufficient porosity can be obtained, a sufficient void volume can be easily obtained, and a state in which a void is closed by swelling during inkjet recording with a hydrophilic binder does not occur. This is a factor that can maintain the ink absorption speed. On the other hand, if this ratio is 20 times or less, cracks are less likely to occur when the porous ink receiving layer is applied as a thick film. A particularly preferred ratio of inorganic pigment to hydrophilic binder is 2.5 to 12 times, most preferably 3 to 10 times.
[0069]
The compound containing a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule used in the present invention is defined as having at least two ethylenic double bonds or acetylene triple bonds in the molecule. Is a compound having It is presumed that the non-aromatic carbon-carbon unsaturated bond moiety is effective in preserving the dye. When adding a large amount of a dye stabilizer to an ink jet recording paper having a porous ink receiving layer, there is a fear that the void capacity may be reduced, and there is a concern about ink absorbency. Therefore, it is preferable that the dye stabilizer has a large effect of stabilizing the dye with a smaller addition amount. It is also necessary that the added dye stabilizer itself stably remains in the porous ink receiving layer. For example, even if the compound has a non-aromatic carbon-carbon unsaturated bond in the molecule, a relatively low-molecular-weight compound such as ethylene itself or allyl alcohol has a high volatility and a large amount of porous ink. It cannot remain stable in the receiving layer. To decrease volatility, it is necessary to increase the molecular weight or introduce a polar substituent, but simply increasing the molecular weight decreases the ratio of unsaturated bonds per unit mass. Is not preferable because it causes a decrease in void volume. For this reason, it is important to provide a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule and not to decrease the ratio of unsaturated bonds per mass while lowering the volatility, and the volatility is small and the volatility per unit mass is small. As a compound having a high ratio of unsaturated bonds, a polymer having a diene monomer as a constitutional unit is very efficient.
[0070]
On the other hand, the dye fixed in the porous ink receiving layer by the cationic polymer or the like is fixed in a certain area in the porous ink receiving layer. In extreme cases, the dye is dyed only on the portion near the outermost surface of the porous ink receiving layer. In order to efficiently improve the storage stability of the dye dyed in such a state, it is particularly preferable that a dye stabilizer is present in the uppermost layer. That is, the top surface of the porous ink receiving layer is a place where the contact with the oxidizing gas in the room occurs with the highest priority, and the consumption of the dye stabilizer tends to occur relatively quickly. However, a compound containing a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule and having a high ratio of unsaturated bonds per unit mass has almost no water solubility, and is therefore water-based. In order to form the ink receiving layer by a process, it is added in the form of an aqueous dispersion (organic fine particles) by emulsification or suspension. However, when a dispersion having a large particle diameter is added to a porous ink receiving layer containing a hydrophilic binder and an inorganic pigment, a problem arises in that it is difficult to obtain a high-density image due to a decrease in gloss and devitrification of a film. Had. By making the opacity of the porous ink receiving layer 1 to 20%, the present inventors can avoid the problems of devitrification and a decrease in concentration of this film.
[0071]
Specific examples of the compound containing a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule include a resin obtained by copolymerizing butadiene alone or another polymerizable monomer, an isoprene resin, a diallyl phthalate resin, and an unsaturated resin. Resins such as polyester resin, furan resin, C5 petroleum resin, terpene resin, and cyclopentadiene resin, diallyl phthalate, triallyloxy-1,3,5-triazinepentaerythritol tetra (meth) acrylate, trimethylolpropanetri (meta) ) Monomers having a plurality of polymerizable groups, such as acrylate and divinylbenzene, or their polymers, unsaturated fatty acids such as linoleic acid, linolenic acid, arachidonic acid, and docosahexaenoic acid, and esterified products thereof, but are not limited thereto. Not a thing.
[0072]
Among these, a polymer having a high ratio of non-aromatic carbon-carbon unsaturated bonds per unit mass is preferably a water-insoluble polymer, and particularly preferably a butadiene polymer. In order to adjust the affinity for the ink solvent, the viscosity of the resin, and the like, it is also preferable to include a monomer such as styrene, acrylonitrile, or (meth) acrylate as a copolymer component in addition to the butadiene monomer. When the copolymer is a copolymer containing butadiene as a constituent unit, the ratio of butadiene in the polymer is preferably at least 30%, more preferably at least 50%. Such polybutadiene is, for example, Nisso PB (Nippon Soda Co., Ltd.), Nisseki polybutadiene (Nippon Petrochemical Co., Ltd.), Poly bd (Idemitsu Petrochemical Co., Ltd.), Hycar (Ube Industries (( Co., Ltd.)), Polyoil (Nippon Zeon Co., Ltd.), JSR RB (JSR Co., Ltd.), and other product series names, and can be easily obtained.
[0073]
As a method for adding a compound having a non-aromatic carbon-carbon unsaturated bond in the molecule to the porous ink receiving layer, the compound may be added to a coating solution for forming the ink absorbing layer, or may be added to the porous layer. , May be supplied by overcoating the ink receiving layer after coating, especially after coating and drying.
[0074]
When added to the coating liquid as in the former case, it is uniformly dissolved in water or an organic solvent or a mixture thereof, and then added, or dispersed into fine oil droplets (particles) by a method such as emulsification dispersion or wet grinding. Can be used. Further, a latex synthesized by an emulsion polymerization method in which a monomer is polymerized in water containing an emulsifier can also be used. At the time of emulsification and dispersion, a high-boiling organic solvent may be added as necessary. When the ink receiving layer is composed of a plurality of layers, it may be added to only one layer, or it may be added to two or more layers or to the coating liquid of all the constituent layers. When used in the form of a latex, there is no limitation on the glass transition temperature, but those having a relatively low glass transition temperature are preferred because diffusion in the porous ink receiving layer easily occurs. Preferred glass transition temperatures are approximately 50 ° C. or less, with 20 ° C. or less being particularly preferred. In such a method in which a compound containing a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule is added to the coating solution in the form of an emulsified dispersion or latex, when the dispersion particle size increases, the ink receiving layer The opacity is increased and the image quality is degraded, so the amount of addition is limited, especially when added to the uppermost layer. The dispersed particle size of the emulsified dispersion or latex added to the ink receiving layer is preferably about 500 nm or less, particularly preferably 100 nm or less, particularly preferably 50 nm or less in the uppermost layer. .
[0075]
When the porous ink receiving layer is formed once and then added by the overcoat method as in the latter, the compound having a non-aromatic carbon-carbon unsaturated bond in the molecule is uniformly dissolved in a solvent. After that, it is preferable to supply the ink to the ink receiving layer. According to this method, even when the water solubility of the non-aromatic carbon-carbon unsaturated bond in the molecule is low, there is no need to prepare the aqueous dispersion liquid as in the former, and the porous ink receiving liquid having low opacity is not required. Layers are easily obtained. In addition, since a dispersant and a protective colloid are not required, it is possible to prevent the gaps from being filled with unnecessary additives in the performance of the recording paper. Compounds containing a plurality of group-containing carbon-carbon unsaturated bonds can be preferably supplied. In addition, when the compound having a non-aromatic carbon-carbon unsaturated bond in the molecule is too large when added by the overcoat method, a film is formed on the surface of the porous ink receiving layer, and the ink absorption property is reduced. Therefore, it is preferable to use a compound having a relatively low molecular weight when added by the overcoat method. When the compound having a non-aromatic carbon-carbon unsaturated bond in the molecule is overcoated, the number average molecular weight is preferably 100,000 or less, more preferably 10,000 or less.
[0076]
The amount of the compound having a non-aromatic carbon-carbon unsaturated bond in the molecule added to the porous ink receiving layer is not particularly limited, but is preferably in the range of 0.01 g to 3 g per m ² of recording paper. Used. When the content is 3 g or less, the compound can prevent the pores of the porous ink receiving layer from being blocked, and can maintain high ink absorbency. When the content is 0.01 g or more, the effects of the present invention can be sufficiently exerted. From this viewpoint, it is more preferably used in the range of 0.1 to ² g per 1 m ² of recording paper.
[0077]
The porous ink receiving layer of the present invention has an opacity of 1 to 20%, a small devitrification of the film, and a high print density. In a print using an aqueous dye ink, unlike a pigment ink in which a coloring material is concentrated on the ink receiving layer, the dye penetrates and dyes to a certain depth, so if the opacity of the ink receiving layer is high, Although the color developability is reduced due to the devitrification of the ink receiving layer, if the opacity of the ink receiving layer is 1 to 20%, a generally acceptable high quality image can be obtained. When the dye is fixed to the ink receiving layer using a mordant, the dye is relatively dyed on the upper layer of the ink receiving layer. Preferably, the transparency is low. In the case of a multilayer structure, the opacity of the uppermost layer is preferably 15% or less, particularly preferably 8% or less.
[0078]
The opacity of the porous ink receiving layer can be measured with a Hunter colorimeter in accordance with JIS-P8138 after peeling off the ink receiving layer. And the opacity may be measured.
[0079]
When fine particles having an anionic surface are used in the ink receiving layer of the recording paper of the present invention, a tertiary amino group or a tertiary amino group having a fixing property to the dye from the viewpoint of improving the water resistance and bleeding resistance of the image. It is preferable to include a cationic polymer having a quaternary ammonium base.
[0080]
Known polymers can be used as the cationic polymer, for example, polyethyleneimine, polyallylamine, dicyandiamide polyalkylenepolyamine, a condensate of dialkylamine and epichlorohydrin, polyvinylamine, polyvinylpyridine, polyvinylimidazole, diallyldimethyl Examples thereof include condensates of ammonium salts and quaternized polyacrylates, and particularly those described in JP-A-10-193776, JP-A-10-217601, and JP-A-11-20300. Is preferred.
[0081]
In the present invention, the cationic polymer can be used without any particular limitation. Particularly preferred are those having a mass average molecular weight of 2,000 to 100,000.
[0082]
As the polymer mordant, a cationic polymer mordant having a primary to tertiary amino group and a quaternary ammonium group is used, but the discoloration and deterioration of light resistance with time are small, and the mordant ability of the dye is sufficiently high. For this reason, a cationic polymer mordant having a quaternary ammonium base is preferred.
[0083]
The cationic polymer preferably used in the present invention is more preferably a polymer having a quaternary ammonium base, and particularly preferably a homopolymer of a monomer having a quaternary ammonium base or other copolymerizable 1 or 2 It is a copolymer with the above monomers.
[0084]
Examples of the monomer having a quaternary ammonium base include the following examples.
[0085]
Embedded image

[0086]
Embedded image

[0087]
The monomer copolymerizable with the quaternary ammonium base is a compound having an ethylenically unsaturated group, and examples thereof include the following specific examples.
[0088]
Embedded image

[0089]
Specific examples of the cationic polymer preferably used in the present invention are shown below, but the present invention is not limited to these.
[0090]
Embedded image

[0091]
Embedded image

[0092]
Embedded image

[0093]
Embedded image

[0094]
In particular, when the cationic polymer having a quaternary ammonium base is a copolymer, the proportion of the cationic monomer is usually at least 10 mol%, preferably at least 20 mol%, particularly preferably at least 30 mol%.
[0095]
The monomer having a quaternary ammonium base may be a single monomer or two or more monomers.
[0096]
Cationic polymers having a quaternary ammonium base are generally highly water-soluble because of the quaternary ammonium base, but do not dissolve sufficiently in water depending on the composition and ratio of the quaternary ammonium base-free monomers to be copolymerized. In some cases, any compound that can be dissolved by dissolving it in a mixed solvent of a water-miscible organic solvent and water can be used in the present invention.
[0097]
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, methyl ethyl ketone and the like. It refers to an organic solvent such as ketones, amides such as N, N-dimethylformamide, etc., which is generally soluble in water by 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.
[0098]
Here, the mass average molecular weight is a value converted into a polyethylene glycol value determined by gel permeation chromatography.
[0099]
When the cationic polymer solution is added to the surface anionic fine particle-containing dispersion, agglomerates may be generated violently. However, when the weight average molecular weight of the cationic polymer is 100,000 or less, Such a phenomenon is unlikely to occur, and therefore, it is easy to obtain a substantially uniform dispersion liquid that does not contain much coarse particles. Excellent glossiness can be expected from ink jet recording paper produced using such a dispersion. From the same viewpoint, the mass average molecular weight is more preferably 50,000 or less.
[0100]
The lower limit of the weight average molecular weight is usually 2,000 or more from the viewpoint of the water resistance of the dye.
The ratio between the fine particles and the cationic polymer can vary depending on the type and average particle size of the fine particles or the type and mass average molecular weight of the cationic polymer.In the present invention, the ratio is such that the surface of the fine particles is replaced with cationic. In order to stabilize, the ratio is preferably 1: 0.01 to 1: 1.
[0101]
In the above range, since the anion component of the fine particles is completely covered with the cation component, there is a possibility that the anion portion of the fine particles and the cation portion of the cationic polymer are ionically bonded to form coarse particles. Absent.
[0102]
The amount of the cationic polymer to be added is usually 0.01 to 0.3, preferably 0.05 to 0.2, in terms of mass ratio to the inorganic fine particles 1.
[0103]
As the inorganic fine particles, inorganic fine particles having a cationic surface and dye fixability are preferable. As the inorganic fine particles having a cationic surface, fumed silica treated with a cationic surface, colloidal silica treated with a cationic surface, alumina, colloidal alumina, pseudo boehmite, and the like can be used.
[0104]
The ink jet recording paper of the present invention preferably contains a polyvalent metal ion in order to improve the water resistance and moisture resistance of the image. The polyvalent metal ion is not particularly limited as long as it is a divalent or higher valent metal ion. Preferred polyvalent metal ions include aluminum ions, zirconium ions, and titanium ions.
[0105]
These polyvalent metal ions can be contained in the ink receiving layer in the form of a water-soluble or water-insoluble salt. Specific examples of the salt containing an aluminum ion include aluminum fluoride, hexafluoroaluminic acid (for example, potassium salt), aluminum chloride, basic aluminum chloride (for example, polyaluminum chloride), and tetrachloroaluminate (for example, sodium). Salt), aluminum bromide, tetrabromoaluminate (eg, potassium salt), aluminum iodide, aluminate (eg, sodium salt, potassium salt, calcium salt), aluminum chlorate, aluminum perchlorate, thiocyanic acid Aluminum, aluminum sulfate, basic aluminum sulfate, aluminum potassium sulfate (alum), ammonium aluminum sulfate (ammonium alum), sodium aluminum sulfate, aluminum phosphate, aluminum nitrate, hydrogen phosphate Minium, aluminum carbonate, polyaluminum silicate, aluminum formate, aluminum acetate, aluminum lactate, aluminum oxalate, aluminum isopropylate, aluminum butyrate, ethyl acetate aluminum diisopropylate, aluminum tris (acetylacetonate), aluminum tris (ethylacetoate) Acetate), aluminum monoacetylacetonate bis (ethylacetoacetonate) and the like.
[0106]
Among these, aluminum chloride, basic aluminum chloride, aluminum sulfate, basic aluminum sulfate and basic aluminum sulfate silicate are preferred, and basic aluminum chloride and basic aluminum sulfate are most preferred.
[0107]
Specific examples of the salt containing a zirconium ion include zirconium difluoride, zirconium trifluoride, zirconium tetrafluoride, hexafluorozirconate (eg, potassium salt), and heptafluorozirconate (eg, sodium salt). , Potassium and ammonium salts), octafluorozirconate (eg, lithium salt), zirconium fluoride, zirconium dichloride, zirconium trichloride, zirconium tetrachloride, hexachlorozirconate (eg, sodium salt and potassium salt) , Zirconium oxychloride (zirconyl chloride), zirconium dibromide, zirconium tribromide, zirconium tetrabromide, zirconium bromide, zirconium triiodide, zirconium tetraiodide, zirconium peroxide, zirconium hydroxide, sulfide Ruconium, zirconium sulfate, zirconium p-toluenesulfonate, zirconyl sulfate, sodium zirconyl sulfate, acidic zirconyl sulfate trihydrate, potassium zirconium sulfate, zirconium selenate, zirconium nitrate, zirconyl nitrate, zirconium phosphate, zirconyl carbonate, zirconyl carbonate Ammonium, zirconium acetate, zirconyl acetate, zirconyl acetate, zirconyl lactate, zirconyl citrate, zirconyl stearate, zirconyl phosphate, zirconium oxalate, zirconium isopropylate, zirconium butyrate, zirconium acetylacetonate, acetylacetone zirconium butyrate, stearin Butyrate, zirconium acetate, bis (acetylacetonato) dichloro Zirconium tris (acetylacetonato) chloro zirconium, and the like.
[0108]
Among these compounds, zirconyl carbonate, zirconyl ammonium carbonate, zirconyl acetate, zirconyl nitrate, zirconyl oxychloride, zirconyl lactate, zirconyl lactate, zirconyl citrate are preferred from the viewpoint that the effect of preventing bleeding after printing, which is the object of the present invention, is more remarkably exhibited. Are preferable, and zirconyl ammonium carbonate, zirconyl acid chloride and zirconyl acetate are particularly preferable.
[0109]
These polyvalent metal ions may be used alone, or two or more different metal ions may be used in combination. The compound containing a polyvalent metal ion may be added to the coating liquid for forming the ink receiving layer, or after the porous ink receiving layer is once applied and dried, applied to the ink receiving layer by an overcoat method. Is also good. When the former compound containing a polyvalent metal ion is added to the coating liquid for forming the ink receiving layer, a method of uniformly dissolving the compound in water or an organic solvent or a mixed solvent thereof, or a wet milling method such as a sand mill, A method of dispersing and adding fine particles to the particles by a method such as emulsification and dispersion can be used. When the ink receiving layer is composed of a plurality of layers, only one layer may be added, or two or more layers or all the constituent layers may be added to the coating solution. When the latter porous ink receiving layer is formed once and then added by an overcoat method, it is preferable to uniformly dissolve a compound containing a polyvalent metal ion in a solvent and then supply the compound to the ink receiving layer. .
[0110]
These polyvalent metal ions are used in a range of generally 0.05 to 20 mmol, preferably 0.1 to 10 mmol, per 1 m ^{2 of} recording paper.
[0111]
The inkjet recording paper of the invention preferably contains a curing agent of a hydrophilic binder for forming a porous void layer. The curing agent that can be used in the present invention is not particularly limited as long as it causes a curing reaction with a water-soluble binder, but boric acid and a salt thereof are preferable, and other known agents can be used. Specifically, it is a compound having a group capable of reacting with a water-soluble binder or a compound which promotes a reaction between different groups of the water-soluble binder, and is appropriately selected and used depending on the type of the water-soluble binder. Specific examples of the curing agent include, for example, epoxy curing agents (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 curing agents (formaldehyde, glyoxal, etc.), active halogen curing agents (2,4-dichloro-6-hydroxy-s-triazine, etc.) And active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum and the like.
[0112]
Boric acid or a salt thereof refers to an oxyacid having a boron atom as a central atom and a salt thereof, and specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, and octaboric acid Acids and their salts.
[0113]
Boric acid having a boron atom and a salt thereof as a curing agent may be used alone or in a mixture of two or more. Particularly preferred is a mixed aqueous solution of boric acid and borax.
[0114]
The aqueous solutions of boric acid and borax can be added only as relatively dilute aqueous solutions, respectively, but by mixing them, a concentrated aqueous solution can be obtained, and the coating solution can be concentrated. Further, there is an advantage that the pH of the aqueous solution to be added can be controlled relatively freely.
[0115]
The total amount of the curing agent is preferably 1 to 600 mg per 1 g of the water-soluble binder.
[0116]
The support used in the present invention may be any of those conventionally known for ink jet recording paper, and may be a water-absorbing support, but is preferably a non-water-absorbing support.
[0117]
Examples of the water-absorbing support that can be used in the present invention include, for example, sheets and plates having general paper, cloth, wood, and the like. Particularly, paper is excellent in water absorption of the base material itself and cost-effective. Is most preferable because it is also excellent. As the paper support, those using wood pulp such as chemical pulp such as LBKP and NBKP, mechanical pulp such as GP, CGP, RMP, TMP, CTMP, CMP and PGW, and waste paper pulp such as DIP can be used. It is. Various fibrous substances such as synthetic pulp, synthetic fiber, inorganic fiber and the like can be used as a raw material as needed.
[0118]
If necessary, various conventionally known additives such as a sizing agent, a pigment, a paper strength agent, a fixing agent, a fluorescent whitening agent, a wet strength agent, and a cationizing agent are added to the paper support. be able to.
[0119]
The paper support can be produced by mixing a fibrous substance such as wood pulp and various additives with various paper machines such as a fourdrinier paper machine, a circular net paper machine and a twin wire paper machine. Further, if necessary, the paper may be subjected to size press processing, starch, polyvinyl alcohol, or the like in a paper making stage or a paper machine, various coating treatments, or calendar treatment.
[0120]
Non-water-absorbing supports which can be preferably used in the present invention include transparent supports and opaque supports. Examples of the transparent support include polyester resin, diacetate resin, triacetate resin, acrylic resin, polycarbonate resin, polyvinyl chloride resin, polyimide resin, cellophane, and a film having a material such as celluloid. Among them, those having the property of resisting radiant heat when used as OHP are preferable, and polyethylene terephthalate is particularly preferable. The thickness of such a transparent support is preferably 50 μm to 200 μm.
[0121]
As the opaque support, for example, a resin-coated paper (so-called RC paper) having a polyolefin resin coating layer in which a white pigment or the like is added to at least one of the base paper, or a white pigment such as barium sulfate added to polyethylene terephthalate is used. So-called white pets are preferred.
[0122]
Prior to the application of the ink absorbing layer, the support is preferably subjected to a corona discharge treatment or a subbing treatment for the purpose of increasing the adhesive strength between the various supports and the ink absorbing layer. Furthermore, the ink jet recording paper of the present invention does not necessarily need to be colorless, and may be a colored recording sheet.
[0123]
In the ink jet recording paper of the present invention, it is particularly preferable to use a paper support in which both sides of the base paper support are laminated with polyethylene, since the recorded image is close to the photographic quality and a high quality image can be obtained at low cost. Such a paper support laminated with polyethylene is described below.
[0124]
The base paper used for the paper support is mainly made of wood pulp, and if necessary, is made of synthetic pulp such as polypropylene or synthetic fiber such as nylon or polyester in addition to wood pulp. As the wood pulp, any of LBKP, LBSP, NBKP, NBSP, LDP, NDP, LUKP, and NUKP can be used, but it is preferable to use LBKP, NBSP, LBSP, NDP, and LDP which contain a large amount of short fibers. However, the ratio of LBSP and / or LDP is preferably 10% by mass to 70% by mass.
[0125]
As the pulp, a chemical pulp containing less impurities (sulfate pulp or sulfite pulp) is preferably used, and pulp having improved whiteness by a bleaching treatment is also useful.
[0126]
Base paper contains sizing agents such as higher fatty acids and alkyl ketene dimers, white pigments such as calcium carbonate, talc, and titanium oxide, paper strength agents such as starch, polyacrylamide, and polyvinyl alcohol, fluorescent whitening agents, and polyethylene glycols. , Etc., a water retention agent, a dispersant, a softening agent such as quaternary ammonium and the like can be appropriately added.
[0127]
The freeness of the pulp used for papermaking is preferably 200 to 500 ml in accordance with the provisions of the CSF, and the fiber length after beating is defined as the mass% of the 24 mesh residue and the 42 mesh residue as defined in JIS-P-8207. The sum with the mass% is preferably 30 to 70%. In addition, it is preferable that the mass% of 4 mesh residue is 20 mass% or less.
[0128]
The basis weight of the base paper is preferably from 30 to 250 g, and particularly preferably from 50 to 200 g. The thickness of the base paper is preferably from 40 to 250 μm.
[0129]
The base paper may be calendered at the papermaking stage or after the papermaking to provide high smoothness. The base paper density is generally 0.7 to 1.2 g / cm ³ (JIS-P-8118). Further, the stiffness of the base paper is preferably 20 to 200 g under the conditions specified in JIS-P-8143.
[0130]
A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, the same sizing agent as that which can be added to the base paper can be used.
[0131]
The pH of the base paper is preferably 5 to 9, when measured by the hot water extraction method specified in JIS-P-8113. The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and Although high-density polyethylene (HDPE) is used, other LLDPE, polypropylene, and the like may be partially used.
[0132]
In particular, as the polyethylene layer on the ink absorbing layer side, it is preferable that rutile or anatase type titanium oxide is added to polyethylene to improve opacity and whiteness as widely used in photographic printing paper. The content of titanium oxide is usually 3% by mass to 20% by mass, preferably 4% by mass to 13% by mass based on polyethylene.
[0133]
Polyethylene-coated paper can be used as glossy paper, or when polyethylene is melt-extruded onto the base paper surface, a so-called molding process is applied to form a matte surface or silk surface that can be obtained with ordinary photographic printing paper. Can be used in the present invention.
[0134]
In the polyethylene-coated paper, it is particularly preferable to maintain the water content in the paper at 3% by mass to 10% by mass.
[0135]
Various additives can be added to the ink jet recording medium of the present invention. For example, organic latex fine particles such as polystyrene, polyacrylates, polymethacrylates, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or a copolymer thereof, a urea resin, or a melamine resin. , Various cationic or nonionic surfactants, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988 and JP-A-62-261476, JP-A-57-74192, JP-A-57-87989, Discoloration inhibitors described in JP-A-60-72785, JP-A-61-146591, JP-A-1-95091 and JP-A-3-13376, and JP-A-59-42993, JP-A-59-52689, and JP-A-62 -280069, 61-242871 and JP-A-4-219266. Fluorescent brighteners, sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, etc. pH adjusters, defoamers, preservatives, thickeners, antistatic agents, mats described in Various known additives such as an agent can also be contained.
[0136]
As a method for manufacturing an ink jet recording medium, each of the constituent layers including the ink absorbing layer may be individually or simultaneously appropriately selected from known coating methods, coated on a support, and dried. Examples of the coating method include a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, and US Patent Nos. 2,761,419 and 2,761,791. A slide bead coating method using a hopper, an extrusion coating method and the like are preferably used.
[0137]
When the slide bead coating method is used, the viscosity of each coating liquid when performing simultaneous multilayer coating is preferably in the range of 5 to 100 mPa · s, and more preferably in the range of 10 to 50 mPa · s. When the curtain coating method is used, the range is preferably 5 to 1200 mPa · s, and more preferably 25 to 500 mPa · s.
[0138]
The viscosity of the coating solution at 15 ° C. is preferably 100 mPa · s or more, more preferably 100 to 30,000 mPa · s, still more preferably 3,000 to 30,000 mPa · s, and most preferably 10 to 30,000 mPa · s. 3,000 to 30,000 mPa · s.
[0139]
As the coating and drying method, the coating liquid is heated to 30 ° C. or more, and after performing simultaneous multi-layer coating, the temperature of the formed coating film is once cooled to 1 to 15 ° C. and dried at 10 ° C. or more. Is preferred. It is preferable to prepare, apply, and dry the coating liquid at a temperature equal to or lower than the Tg of the thermoplastic resin so that the thermoplastic resin contained in the surface layer does not form a film during the preparation, coating, and drying of the coating liquid. More preferably, the drying is carried out at a wet bulb temperature of 5 to 50 ° C. and a film surface temperature of 10 to 50 ° C. In addition, as a cooling method immediately after the application, it is preferable to perform a horizontal setting method from the viewpoint of uniformity of the formed coating film.
[0140]
In addition, it is preferable to have a step of storing at a temperature of 35 ° C. or more and 70 ° C. or less for 24 hours or more and 60 days or less during the production process.
[0141]
The heating conditions are not particularly limited as long as they are stored at a temperature of 35 ° C. or more and 70 ° C. or less for 24 hours or more and 60 days or less. Preferred examples include, for example, 36 ° C. for 3 days to 4 weeks. It is 2 days to 2 weeks at 40 ° C, or 1 to 7 days at 55 ° C. By performing this heat treatment, the curing reaction of the water-soluble binder can be promoted, or the crystallization of the water-soluble binder can be promoted. As a result, preferable ink absorbency can be achieved.
[0142]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples. In the examples, "%" represents mass% unless otherwise specified.
[0143]
Example 1
Preparation of Silica Dispersion D-1 A silica dispersion B containing 25% of fumed silica (manufactured by Nippon Aerosil Co., Ltd .; Aerosil 300) having an average primary particle size of about 0.007 μm, which is uniformly dispersed in advance. -1 (pH 2.6, containing 0.5% of ethanol), 400 L of an aqueous solution C-1 containing 12% of a cationic polymer P-1, 10% of n-propanol and 2% of ethanol (pH 2.5, 110 L of an antifoaming agent SN-381 manufactured by San Nopco Co., Ltd.) was added at room temperature with stirring at 3000 rpm. Next, 54 L of a mixed aqueous solution A-1 (3% concentration) of boric acid and borax at a mass ratio of 1: 1 was gradually added thereto with stirring.
[0144]
Next, the mixture was dispersed with a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd. at a pressure of 3000 N / cm ² , and the total amount was finished to 630 L with pure water to obtain a substantially transparent silica dispersion D-1.
[0145]
Preparation of Silica Dispersion D-2 400 L of the above silica dispersion B-1 was added to an aqueous solution C-2 containing 12% of cationic polymer P-2, 10% of n-propanol and 2% of ethanol (pH = 2. To 120 L of 5), the mixture was added at room temperature with stirring at 3000 rpm, and then 52 L of the mixed aqueous solution A-1 was gradually added with stirring. Then, the mixture was dispersed with a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd. at a pressure of 3000 N / cm ² , and the total amount was adjusted to 630 L with pure water to obtain a substantially transparent silica dispersion D-2.
[0146]
The silica dispersions D-1 and D-2 were filtered using a TCP-30 type filter manufactured by Advantech Toyo having a filtration accuracy of 30 μm.
[0147]
Preparation of Oil Dispersion 20 kg of diisodecyl phthalate and 20 kg of an antioxidant (AO-1) are dissolved in 45 kg of ethyl acetate by heating, containing 8 kg of acid-treated gelatin, 2.9 kg of cationic polymer P-1 and 5 kg of saponin. After mixing with 210 L of an aqueous gelatin solution at 55 ° C. and emulsifying and dispersing with a high-pressure homogenizer, the whole was finished to 300 L with pure water to prepare an oil dispersion.
[0148]
Embedded image

[0149]
Preparation of Coating Liquid Using the dispersion liquids prepared above, the following additives were sequentially mixed to prepare coating liquids for the porous ink receiving layer. In addition, each addition amount was represented by the amount per 1 L of the coating solution.
[0150]
(Coating solution for the first layer; lowermost layer)
580 ml of silica dispersion D-1
5 ml of 10% aqueous solution of polyvinyl alcohol (Kuraray; PVA203)
290 ml of 5% aqueous solution of polyvinyl alcohol (average degree of polymerization: 3800, saponification degree 88%)
30ml oil dispersion
42 ml of latex dispersion (AE-803, manufactured by Showa Polymer)
8.5 ml of ethanol
Make up to 1000ml with pure water.
[0151]
(Coating solution for the second layer)
580 ml of silica dispersion D-1
5 ml of 10% aqueous solution of polyvinyl alcohol (Kuraray; PVA203)
270 ml of 5% aqueous solution of polyvinyl alcohol (average degree of polymerization: 3800, saponification degree 88%)
20ml oil dispersion
Latex dispersion (AE-803, manufactured by Showa Polymer Co., Ltd.) 22 ml
8 ml of ethanol
Make up to 1000ml with pure water.
[0152]
(Coating solution for the third layer)
630 ml of silica dispersion D-2
5 ml of 10% aqueous solution of polyvinyl alcohol (Kuraray; PVA203)
270 ml of 5% aqueous solution of polyvinyl alcohol (average degree of polymerization: 3800, saponification degree 88%)
Oil dispersion 10ml
Latex dispersion (AE-803, 5 ml, manufactured by Showa Polymer Co., Ltd.)
3 ml of ethanol
Make up to 1000ml with pure water.
[0153]
(4th layer coating solution; top layer)
660 ml of silica dispersion D-2
5 ml of 10% aqueous solution of polyvinyl alcohol (Kuraray; PVA203)
Average degree of polymerization of polyvinyl alcohol: 3800, saponification degree 88%) 250 ml of 5% aqueous solution
3% of 4% aqueous solution of cationic surfactant-1
2 ml of a 25% aqueous solution of saponin
3 ml of ethanol
Make up to 1000ml with pure water.
[0154]
Embedded image

[0155]
Each coating solution prepared as described above was filtered through a TCPD-30 filter manufactured by Advantech Toyo Co., Ltd. having a filtration accuracy of 20 μm, and then filtered through a TCPD-10 filter.
[0156]
Preparation of Recording Paper-1 Next, each of the above coating solutions was coated on a paper support coated with polyethylene on both sides at 40 ° C. so as to have a wet film thickness described below, using a slide hopper type coater to form four layers. Co-applied.
[0157]
<Wet film thickness>
First layer: 42 μm
Second layer: 39 μm
Third layer: 44 μm
4th layer: 38 μm
The paper support used was the following support wound in a roll having a width of about 1.5 m and a length of about 4000 m.
[0158]
The paper support used had a moisture content of 8% and a basis weight of 170 g, and the surface of the photographic base paper was extruded at a thickness of 35 μm and melt-coated with polyethylene containing 6% of anatase type titanium oxide. 40 μm polyethylene was extruded at a thickness of 35 μm and melt coated. After a corona discharge on the front side, a subbing layer was coated with polyvinyl alcohol (PVA235 manufactured by Kuraray Co., Ltd.) so as to be 0.05 g per 1 m ² of the recording medium. A back layer containing about 0.4 g of a styrene-acrylate latex binder, 0.1 g of an antistatic agent (cationic polymer) and 0.1 g of about 2 μm silica as a matting agent was applied.
[0159]
Drying after application of the ink receiving layer coating liquid is performed by passing the cooling zone maintained at 5 ° C. for 15 seconds to lower the film surface temperature to 13 ° C., and then appropriately setting the temperatures of the plurality of drying zones. After drying, it was wound up in a roll to obtain Comparative Recording Paper-1.
[0160]
Fabricated recording sheets -1 Poly bd R45HT recording paper 2 (manufactured by Idemitsu Petrochemical Co., number average molecular weight 2,800) was dissolved in ethyl acetate 5% solution of impregnated by 20ml overcoat per 1 m ² recording paper -2 Was prepared.
[0161]
Preparation of recording paper-3 Same as recording paper-2 except that Poly bd R45HT used for preparation of recording paper-2 was replaced with Poly bd R15HT (manufactured by Idemitsu Petrochemical Co., Ltd .; number average molecular weight 1,200). Thus, recording paper-3 was produced.
[0162]
Preparation of Recording Paper-4 Recording was performed in the same manner as recording paper-2 except that Poly bd R45HT used for preparing recording paper-2 was replaced with Polyoil 130 (manufactured by Zeon Corporation; number average molecular weight: 3,000). Paper-4 was produced.
[0163]
Preparation of Recording Paper-5 Recording Paper-2 was used except that Poly bd R45HT used for preparation of Recording Paper-2 was replaced with Nisso PBB-1000 (Nippon Soda Co., Ltd .; number average molecular weight 900-1300). In the same manner, recording paper-5 was produced.
[0164]
Preparation of recording paper-6 Same as recording paper-2 except that Poly bd R45HT used for preparation of recording paper-2 was replaced with Daiso Dap S (polyallyl phthalate manufactured by Daiso Corporation; average molecular weight: 35,000). Thus, recording paper-6 was produced.
[0165]
Preparation of Recording Paper-7 In the preparation of recording paper-4, the fumed silica used for preparing the silica dispersion B-1 was replaced with Aerosil 90G (manufactured by Nippon Aerosil Co., Ltd .; average primary particle size: 20 nm), and silica was used as it was. Recording paper-7 was produced in the same manner as recording paper-4 except that dispersion D-1 and silica dispersion D-2 were prepared.
[0166]
Preparation of Recording Paper-8 to 12 In the preparation of Recording Paper-7, recording papers 8 to 12 were prepared in the same manner as recording paper-1 except that organic fine particles were added to the coating solution of each layer as shown in Table 1. Was prepared.
[0167]
[Table 1]

[0168]
Preparation of Recording Paper-13 Zircosol ZA (aqueous zirconyl acetate solution manufactured by Daiichi Kazoku Kagaku Kogyo Co., Ltd.) was diluted with pure water, spray-coated, and the amount of zirconyl acetate applied to recording paper-3 was 0.5 g /. dried was uniformly applied so as to m ^2, and to produce a recording paper -13.
[0169]
The following items were evaluated for the ink jet recording papers-1 to 13 obtained as described above.
[0170]
(Image storability)
After recording a solid cyan image on the recording paper obtained as above using BJ-F870 manufactured by Canon Inc., the outside air was directly blown onto the printed image for one month to evaluate the gas fading property of the cyan image. . The fading was indicated by the residual ratio of the initial density.
[0171]
(Mottle (mottle))
A green solid was printed with a Canon inkjet printer BJF870, and the uniformity was visually evaluated.
◎: A completely uniform solid image ；: Uniform feeling at an observation distance of 30 cm or more Δ: Uniform feeling at an observation distance of 60 cm or more X: Mottled even at an observation distance of 60 cm or more
[0172]
(Highest concentration)
A black solid was printed using an inkjet printer PM900C manufactured by Seiko Epson Corporation, and the reflection density was measured.
[0173]
(crack)
The coated surface was visually observed, and the crack state was evaluated according to the following criteria.
◎: Cracks are hardly observed ○: Small cracks of less than 0.5 mm are observed at several points Δ: Coarse cracks of 0.5 mm or more are observed at several points ×; Coarse cracks of 0.5 mm or more are observed Observed throughout.
[0174]
(Bleeding)
A magenta thin line (width 1/300 × 2.54 cm) was printed with an inkjet printer PM900C manufactured by Seiko Epson Corporation, and left for one week in an environment of 23 ° C. and 80% RH to determine the rate of increase in the line width of the thin line. Was.
[0175]
(Opacity)
The opacity of the ink receiving layer was determined by applying the coating solutions used in Examples and Comparative Examples to a polyethylene film in the same manner as described above and drying the same, and based on JIS-P-8138, a Hunter-type colorimeter (manufactured by Toyo Seiki) Was measured by Table 2 shows all the evaluation results.
[Table 2]

[0177]
From Table 2, it can be seen that the ink jet recording paper of the present invention has improved image storability, high density, and excellent images free of cracks, bleeding and mottle.
[0178]
【The invention's effect】
According to the present invention, it has been possible to provide an ink jet recording sheet which has good ink absorption, high color density, high photographic quality and high quality recording, and excellent storage stability, especially excellent gas fading.

Claims (7)

A porous ink receiving layer containing a compound containing a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule, an inorganic pigment and a hydrophilic binder, wherein the opacity of the porous ink receiving layer is 1 to 20% of an ink jet recording paper. 2. The ink-jet printer according to claim 1, wherein the compound containing a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule is a polymer or a copolymer obtained by using butadiene as a monomer. Recording sheet. 3. The ink jet recording paper according to claim 1, wherein the compound containing a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule is polybutadiene having a number average molecular weight of 10,000 or less. The porous ink receiving layer comprises silica particles having an average primary particle diameter of 3 to 30 nm and a hydrophilic binder, and the silica particles are 2 to 20 times in mass ratio to the hydrophilic binder. Item 4. The ink jet recording paper according to any one of items 1 to 3. The ink jet recording paper according to any one of claims 1 to 4, wherein the porous ink receiving layer contains a cationic resin. A porous ink receiving layer containing silica particles having an average primary particle diameter of 3 to 30 nm and a hydrophilic binder, and the silica particles having a mass ratio of 2 to 20 times the hydrophilic binder, has a number average molecular weight of 10,000 or less. The inkjet recording paper according to any one of claims 1 to 5, wherein a polymer solution containing a diene monomer in a constituent unit is overcoated. 7. An ink jet recording sheet according to claim 1, wherein the ink jet recording sheet is for an aqueous dye ink.