JP2004358877A - Inkjet recording paper sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording paper sheet, which has high antifading effects of a print image, favorable ink absorbency, in which no crack develops at coating and which is excellent in anticoloring (such as anti-yellowing) of paper face. <P>SOLUTION: This inkjet recording paper sheet has a porous ink absorbing layer including a compound with a plurality of non-aromatic carbon-carbon unsaturated linkages in a molecule, polyvalent metal salt, inorganic fine particles and binder on a support. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００６８】
式中、Ｒ、Ｒ^１、Ｒ^２、Ｒ^３は水素、アルキル基、アルカンを含む置換基、アルケンを含む置換基、シアノ基、ニトロ基、フェニル基などの芳香環を含む置換基、イミダゾールなどの複素環を含む置換基を表す。
【００６９】
具体的には尿素、ビウレット、セミカルバジド塩酸塩、ビウレア、１−メチル尿素、１，１−ジメチル尿素、１，３−ジメチル尿素、１，１，３−トリメチル尿素、１，１，３，３−テトラメチル尿素、１−エチル尿素、１，１−ジエチル尿素、１，３−ジエチル尿素、１，１，３−トリエチル尿素、１−（ｎ−プロピル）尿素、１−（ｎ−ブチル）尿素、１−（ｔｅｒｔ−ブチル）尿素、１−アリル尿素、１，３−ジアリル尿素、１−フェニル尿素、１，１−ジフェニル尿素、１，３−ジフェニル尿素、１−（ｏ−トリル）尿素、１−（ｍ−トリル）尿素、フェニルアセチル尿素、１−（ベンジル）尿素、１−ヒドロキシ尿素、１，３−ビス（トリメチルシリル）尿素、ビス（ペンタメチレン）尿素、２−イミダゾロン、バルビツル酸、１，３−ジシクロヘキシル尿素、ニトロソ尿素、ジシアンジアミジン、ヒダントイン等が挙げられ、２種以上を併用してもよい。これらの中でも尿素が特に好ましい。
【００７０】
本発明に係る尿素化合物を添加する層は、インク受容層が１層の場合はその層に、また複数の層から構成される場合には、少なくとも１層または全層に添加してもよいが、特に２層以上の場合には上層に尿素化合物、下層に前記非芳香族性の炭素−炭素不飽和結合を複数個有する化合物を含有することが好ましい形態である。
【００７１】
本発明に係る尿素化合物を添加する場合には、本発明の効果の点から、記録用紙１ｍ２当たりの添加量が０．０５〜５ｇであることが好ましく、０．１〜１．０ｇがより好ましい。０．０５ｇ未満であると効果が得られにくく、５ｇ以上であると塗布液の安定性が悪くなるためである。
【００７２】
（カチオン性ポリマーの説明）
本発明のインクジェット記録用紙には、記録後の保存による画像の滲みを防止する目的でカチオン性ポリマーを用いることが好ましい。
【００７３】
カチオン性ポリマーの例としては、ポリエチレンイミン、ポリアリルアミン、ポリビニルアミン、ジシアンジアミドポリアルキレンポリアミン縮合物、ポリアルキレンポリアミンジシアンジアミドアンモニウム塩縮合物、ジシアンジアミドホルマリン縮合物、エピクロルヒドリン・ジアルキルアミン付加重合物、ジアリルジメチルアンモニウムクロライド重合物、ジアリルジメチルアンモニウムクロライド・ＳＯ_２共重合物、ポリビニルイミダゾール、ビニルピロリドン・ビニルイミダゾール共重合物、ポリビニルピリジン、ポリアミジン、キトサン、カチオン化澱粉、ビニルベンジルトリメチルアンモニウムクロライド重合物、（２−メタクロイルオキシエチル）トリメチルアンモニウムクロライド重合物、ジメチルアミノエチルメタクリレート重合物、等が挙げられる。
【００７４】
また、化学工業時報平成１０年８月１５，２５日に述べられるカチオン性ポリマー、三洋化成工業株式会社発行「高分子薬剤入門」に述べられる高分子染料固着剤が例として挙げられる。
【００７５】
本発明で好ましく用いられるカチオン性ポリマーとして、ポリアミドポリアミン−エピハロヒドリン樹脂が挙げられ、前記化合物と併用することで、皮膜が膨潤するのを防ぎ、インク吸収性や褪色防止効果が更に向上する。
【００７６】
ポリアミドポリアミン−エピハロヒドリン樹脂の中でも、特にポリアミドポリアミン−エピクロルヒドリン樹脂が好ましい。ポリアミドポリアミン−エピハロヒドリン樹脂の使用量は、塗布液中の無機微粒子や水溶性樹脂の量によって変り得るが、記録媒体にした時にインク吸収層中に０．０１〜１．０ｇ／ｍ^２であることが好ましく、０．０１〜０．５ｇ／ｍ^２であることがより好ましい。０．０１ｇ／ｍ^２未満ではインク吸収性及び褪色を改善する効果が少なく、１．０ｇ／ｍ^２を越えると塗布乾燥時にクラックが発生するなどの故障が生じることがあ
る。
【００７７】
ポリアミドポリアミン−エピクロルヒドリン樹脂は、エポキシ化ポリアミド樹脂とも呼ばれ、下記式で示される構造を有する化合物である。
【００７８】
【化２】

【００７９】
前記式中、ｎは重合度を表す。前記重合度としては、５００〜１００００が好ましい。前記重合度が、５００未満であると人体に害を与える可能性が考えられ、１００００を越えると安定性に欠けることがある。
【００８０】
本発明に用いられるポリアミドポリアミン−エピハロヒドリン樹脂の製造方法としては、例えば特開平６−１８４２に記載された方法が挙げられる。
【００８１】
前記ポリアミドポリアミン−エピハロヒドリン樹脂としては、１種単独で使用してもよいし、異なる重合度のものを混合して併用してもよい。また、前記ポリアミドポリアミン−エピクロルヒドリン樹脂は、適宜合成したものでもよいし、市販品を用いてもよい。
【００８２】
（硬膜剤の説明）
本発明のインクジェット記録用紙は、多孔質インク受容層を形成する水溶性バインダーの硬膜剤を添加することが好ましい。
【００８３】
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無いが、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或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−４−ヒドロキシ−１，３，５−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。
【００８４】
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及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、五ホウ酸及び八ホウ酸及びそれらの塩が挙げられる。
【００８５】
硬化剤としての硼素原子を有するホウ酸及びその塩は、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。
【００８６】
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でき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でき、塗布液を濃縮化することができる。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できる利点がある。
【００８７】
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。また、請求項３に対応する供給量としては、上記水溶性バインダー１ｇ当たり１００〜６００ｍｇが好ましい。
【００８８】
（支持体の説明）
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いが、非吸水性支持体であることが好ましい。
【００８９】
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。また、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。
【００９０】
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。
【００９１】
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。また、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。
【００９２】
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として使用された時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。
【００９３】
また、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。
【００９４】
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無く、着色された記録シートであってもい。
【００９５】
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。
【００９６】
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。但し、ＬＢＳＰ及びまたはＬＤＰの比率は１０質量％〜７０質量％が好ましい。
【００９７】
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。
【００９８】
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できる。
【００９９】
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。
【０１００】
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。
【０１０１】
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できる。原紙密度は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。
【０１０２】
原紙表面には表面サイズ剤を塗布してもく、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。
【０１０３】
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。
【０１０４】
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できる。
【０１０５】
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。
【０１０６】
ポリエチレン被覆紙は光沢紙として用いることも、また、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。
【０１０７】
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。
【０１０８】
（添加剤の説明）
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できる。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、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褪色防止剤、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。
【０１０９】
（製造方法の説明）
次に、本発明のインクジェット記録用紙の製造方法について説明する。
【０１１０】
インクジェット記録用紙の製造方法としては、インク吸収層を含む各構成層を、各々単独に或いは同時に、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、或いは米国特許第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。
【０１１１】
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、更に好ましくは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、更に好ましくは２５〜５００ｍＰａ・ｓの範囲である。
【０１１２】
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、更に好ましくは３，０００〜３０，０００ｍＰａ・ｓであり、最も好ましいのは１０，０００〜３０，０００ｍＰａ・ｓである。
【０１１３】
塗布及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。
【０１１４】
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。
【０１１５】
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無いが、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、或いは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、或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。
【０１１６】
（インク）
尚、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できる。
【０１１７】
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。
【０１１８】
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、反応性染料或いは食品用色素等の水溶性染料、或いは水分散性顔料が使用できる。
【０１１９】
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（またはエチル）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。
【０１２０】
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。
【０１２１】
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。
【０１２２】
【実施例】
以下、本発明の実施例を挙げて具体的に説明するが、本発明の実施形態はこれらに限定されるものではない。尚、実施例中で「％」は、特に断りの無い限り質量％を表す。
【０１２３】
《インクジェット記録用紙の作製》
〔分散液の調製〕
（シリカ分散液（Ａ−１）の調製）
予め均一に分散されているｐＨ３．０に調整された２０％シリカ分散液（日本アエロジル社製：アエロジル３００、１次粒径７ｎｍ）５００Ｌに、カチオン性ポリマー（Ｐ−１）２０％水溶液７５Ｌ及びエタノール１０Ｌ、ホウ酸１ｇ及びほう砂２ｇを溶解した水溶液６０Ｌを添加し、三和工業株式会社製の高圧ホモジナイザーで３ｋＮ／ｃｍ^２の圧力で分散し、全量を純水で６５０Ｌに仕上げ、ほぼ透明なシリカ分散液（Ａ−１）を得た。
【０１２４】
（シリカ分散液（Ａ−２）の調製）
上記シリカ分散液（Ａ−１）の調製において、カチオン性ポリマー（Ｐ−１）を（Ｐ−２）に代えた以外は同様にして、シリカ分散液（Ａ−２）の調製を行い、ほぼ透明なシリカ分散液（Ａ−２）を得た。
【０１２５】
【化３】

【０１２６】
（シリカ分散液（Ａ−３）の調製）
上記シリカ分散液（Ａ−１）の調製において、アエロジル３００をレオロシールＱＳ−２０（トクヤマ社製：１次粒径１４ｎｍ）に代えた以外は同様にして、シリカ分散液（Ａ−３）の調製を行い、ほぼ透明なシリカ分散液（Ａ−３）を得た。
【０１２７】
（オイル分散液（Ｂ−１）の調製）
以下に記載の添加剤を混合し、高圧ホモジナイザーで分散し、全量を純水で３０Ｌに仕上げた。
【０１２８】

（オイル分散液（Ｂ−２）の調製）
以下に示すＡ液及びＢ液をそれぞれ加熱溶解し、５５℃でＡ液とＢ液を混合後、高圧ホモジナイザーで乳化分散し、全量を純水で３０Ｌに仕上げて、オイル分散液（Ｂ−２）を調製した。
【０１２９】

（オイル分散液（Ｂ−３）〜（Ｂ−６）の調製）
オイル分散液（Ｂ−１）の調製において、ポリブタジエン（日本曹達（株）製；Ｂ−２０００）の代わりに、他の本発明に係る分子内に非芳香族性の炭素−炭素不飽和結合を複数個有する化合物を同量用いて、下記オイル分散液を調製した。
【０１３０】
オイル分散液（Ｂ−３）：Ｐｏｌｙ Ｉｐ（出光石油化学（株）製：数平均分子量２５００）
オイル分散液（Ｂ−４）：Ｂ−３０００（日本曹達（株）製：数平均分子量３０００）
オイル分散液（Ｂ−５）：Ｐｏｌｙｏｉｌ １１０（日本ゼオン（株）製：数平均分子量１６００）
オイル分散液（Ｂ−６）：Ｅ−１０００−８（新日本石油化学社製：数平均分子量１０００）
（オイル分散液（Ｂ−７）、（Ｂ−８）の調製）
オイル分散液（Ｂ−２）の調製において、ポリブタジエン（日本曹達（株）製；Ｂ−１０００）の代わりに、他の本発明に係る分子内に非芳香族性の炭素−炭素不飽和結合を複数個有する化合物を同量用いて、下記オイル分散液を調製した。
【０１３１】
オイル分散液（Ｂ−７）：Ｍ−１０００−２０（新日本石油化学社製：数平均分子量約１０００）
オイル分散液（Ｂ−８）：Ｐｏｌｙ−ｂｄ Ｒ４５ＨＴ（出光石油化学（株）製：数平均分子量２８００）
〔インク吸収層塗布液の調製〕
上記調製した各分散液を使用して、４０℃で撹拌しながら、以下に記載の各添加剤を順次混合し、各塗布液を作製した。
【０１３２】

【０１３３】

【０１３４】

【０１３５】

【０１３６】
上記調製した各塗布液は、調製後に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。
【０１３７】
〔記録用紙の作製〕
（記録用紙１の作製：比較例）
上記調製した４０℃の各塗布液を、下記の湿潤膜厚となる塗布条件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。
【０１３８】
〈湿潤膜厚〉
第１層：４２μｍ
第２層：３９μｍ
第３層：４４μｍ
第４層：４０μｍ
尚、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。
【０１３９】
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当たり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及び約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。
【０１４０】
インク受容層塗布液を、上記支持体上に塗布した後、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にて２０〜４０℃の温風を６〜７分間吹付けて乾燥を行った後、ロール状に巻き取って記録用紙１を得た。
【０１４１】
（記録用紙２の作製：本発明）
記録用紙１の作製において、第３層にジルコゾールＺＡ（第一稀元素化学工業（株）製；酢酸ジルコニル水溶液）を０．５ｇ／ｍ^２の塗布量となるように水で希釈し添加した。この塗布液を同様に塗布して記録用紙２を作製した。
【０１４２】
（記録用紙３の作製：本発明）
記録用紙２の作製において、全層塗布液に尿素１０％水溶液を各々３６ｍｌ添加した。この塗布液を同様に塗布して記録用紙３を作製した。
【０１４３】
（記録用紙４の作製：本発明）
記録用紙３の作製において、第１、２層用塗布液のオイル分散液（Ｂ−１）の代わりにオイル分散液（Ｂ−３）を使用し、更にジルコゾールＺＡを硫酸マグネシウムに変更した以外は同様にして、記録用紙４を作製した。
【０１４４】
（記録用紙５の作製：本発明）
記録用紙３の作製において、第１、２層用塗布液のオイル分散液（Ｂ−１）をスチレンブタジエンラテックス（日本ゼオン（株）製：Ｌｘ４３８Ｃ）に代えた以外は同様にして記録用紙５を作製した。
【０１４５】
（記録用紙６の作製：比較例）
記録用紙１の作製において、第１層用塗布液のオイル分散液（Ｂ−１）を添加せず、更に硫酸マグネシウムを０．５ｇ／ｍ^２の塗布量となるように水で希釈し添加した。この塗布液を同様に塗布して記録用紙６を作製した。
【０１４６】
（記録用紙７の作製：本発明）
記録用紙１の作製において、第１、２層用塗布液のオイル分散液（Ｂ−１）の代わりにオイル分散液（Ｂ−４）を使用し、更に第３層にポリ塩化アルミニウム化合物（多木化学（株）製：タキバイン＃１５００（ＰＡＣ））を０．５ｇ／ｍ^２の塗布量となるように水で希釈し添加し、第３、４層用塗布液に尿素１０％水溶液を各々３６ｍｌ添加した。この塗布液を同様に塗布して記録用紙７を作製した。
【０１４７】
（記録用紙８の作製：本発明）
記録用紙３の作製において、第１、２層用塗布液のオイル分散液（Ｂ−１）を（Ｂ−５）に代えた以外は同様にして記録用紙８を作製した。
【０１４８】
（記録用紙９の作製：本発明）
記録用紙４の作製において、第１、２層用塗布液のオイル分散液（Ｂ−３）の代わりにオイル分散液（Ｂ−６）を使用した以外は同様にして記録用紙９を作製した。
【０１４９】
（記録用紙１０の作製：本発明）
記録用紙７の作製において、第１、２層用塗布液のオイル分散液（Ｂ−４）の代わりにオイル分散液（Ｂ−７）を使用した以外は同様にして記録用紙１０を作製した。
【０１５０】
（記録用紙１１の作製：本発明）
記録用紙１の作製において、第１、２層用塗布液のオイル分散液（Ｂ−１）の代わりにオイル分散液（Ｂ−２）を使用し、全層塗布液に尿素の１０％水溶液を各々３６ｍｌ添加した。この塗布液を同様に塗布して記録用紙１１を作製した。
【０１５１】
（記録用紙１２の作製：本発明）
記録用紙１１の作製において、第１、２層用塗布液のオイル分散液（Ｂ−２）を（Ｂ−８）に代えた以外は同様にして記録用紙１２を作製した。
【０１５２】
（記録用紙１３の作製：本発明）
記録用紙３の作製において、第１層、第２層用塗布液のオイル分散液（Ｂ−１）の代わりにオイル分散液（Ｂ−２）を使用した以外は同様にして、記録用紙１３を作製した。
【０１５３】
（記録用紙１４の作製：本発明）
記録用紙３の作製において、シリカ分散液（Ａ−２）をシリカ分散液（Ａ−３）に代え、第３層用塗布液のジルコゾールＺＡをタキバイン＃１５００（多木化学（株）製：ＰＡＣ）に代えた以外は同様にして記録用紙１４を作製した。
【０１５４】
（記録用紙１５の作製：本発明）
記録用紙７の作製において、カチオン性ポリアミド樹脂（ＷＳ５５２）を除いた以外は同様にして記録用紙１５を作製した。
【０１５５】
（記録用紙１６の作製：本発明）
記録用紙３の作製において、オイル分散液（Ｂ−１）を第１層、第２層用塗布液ではなく、第３層、第４層用塗布液に添加した以外は同様にして記録用紙１６を作製した。
【０１５６】
各記録用紙の構成の詳細を表１に示した。
〔記録用紙の各特性評価〕
上記作製した各記録用紙について下記の各評価を行った。
【０１５７】
（ガス褪色性）
上記作製した各記録用紙について、セイコーエプソン株式会社製インクジェットプリンタＰＭ−９７０Ｃを用いてＣ（シアン）のベタ画像を印字し、３ｐｐｍのオゾン雰囲気下で４８時間処理を行い、ガス褪色性を評価した。ガス褪色性は初期濃度の残存率で示した。
【０１５８】
（インク吸収性）
セイコーエプソン株式会社製インクジェットプリンタＰＭ−９５０Ｃを用いて青のベタ印字を行い、その印字部を目視観察し、下記の基準によりインク吸収性の評価を行った。
【０１５９】
◎：印字部に印字ムラが無い。（実用上問題なし）
○：印字部にややマダラ状のムラが認められる。（実用上問題なし）
△：印字部にかなりマダラ状のムラが認められる。（実用上問題あり）
×：印字部がほとんどマダラ状のムラである。（実用上問題あり）
（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。
【０１６０】
○：１ｍｍ以上のひび割れが０〜５個観察される。（実用上問題なし）
△：１ｍｍ以上のひび割れが６〜１０個観察される。（実用上問題なし）
×：１ｍｍ以上のひび割れが１１個以上観察される。（実用上問題あり）
（紙面の着色（黄変））
各記録用紙に３ｐｐｍのオゾン雰囲気下で５時間処理を行い、その後３０℃８０％で２週間保存した時の紙面を目視で観察し、下記の基準により紙面の着色の評価を行った。
【０１６１】
◎：紙面が全く変色していない。（実用上問題なし）
○：紙面がかすかに変色している。（実用上問題なし）
△：紙面がやや変色（黄変）している。（実用上問題あり）
×：紙面がほとんど変色（黄変）している。（実用上問題あり）
以上の結果を表１に示した。
【０１６２】
【表１】

【０１６３】
上表の結果より、本発明の構成の試料は、比較例に対しガス褪色性、インク吸収性、ひび割れ、紙面の着色（黄変）に優れていることが分かる。
【０１６４】
【発明の効果】
本発明により、プリント画像の褪色防止効果が高く、インク吸収性が良好で、塗布時にひび割れが起きない、紙面の着色（黄変等）防止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る。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inkjet recording sheet (hereinafter, simply referred to as a recording sheet) used for inkjet image recording.
[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). 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 high 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 a water-soluble solvent as ink solvents, and those using non-aqueous oil-based solvents.Each type 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]
The pigment ink has high durability of the image, but the gloss tends to change like an image, and as a result, it is difficult to obtain a print close to photographic quality. On the other hand, when a water-soluble dye ink is used, the sharpness of the image is high, and A color print comparable in photographic quality with uniform surface gloss is 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 greatly discolored by an oxidizing gas such as ozone present in the air. That is a challenge. In particular, a void-type recording paper provided with a fine porous layer has a large contact area between the dye and room air, and is susceptible to the oxidizing gas in the air, and an improvement is desired.
[0006]
In order to improve such deterioration due to storage, it has been conventionally proposed to add various antioxidants as anti-fading agents.
[0007]
For example, JP-A-57-87989, JP-A-57-74192 and JP-A-60-72785 disclose ink jet recording papers containing various compounds as antioxidants, and JP-A-57-74193 discloses an ultraviolet absorber. JP-A-61-154989 discloses that an ink jet recording paper containing hydrazide may be added, and JP-A-61-146591 may add a hindered amine antioxidant. Japanese Patent Application Laid-Open Nos. 1-367480 disclose adding a nitrogen-containing heterocyclic mercapto compound to JP-177279 and adding a thioether-based antioxidant to JP-A-1-115677 and JP-A-1-35479. JP-A-3-13376 discloses that a hindered phenol-based antioxidant having a specific structure can be added. The addition of an antioxidant and a hindered amine-based antioxidant in combination may include adding ascorbic acids to JP-A-7-195824 and JP-A-8-150773, and adding zinc sulfate to JP-A-7-149037. JP-A-7-314882 may include thiocyanates and the like, and JP-A-7-314882 may add a thiourea derivative or the like. No. 108617 may contain saccharides, JP-A-8-118791 may add a phosphoric acid-based antioxidant, and JP-A-8-300807 discloses nitrites, sulfites, thiosulfates and the like. JP-A-9-267544 describes that a hydroxylamine derivative is added.
[0008]
However, the effect is not always sufficient in ink jet recording paper having fine voids, and when a large amount of such various anti-fading agents is added in order to obtain a sufficient anti-fading effect, the ink absorption of the porous layer is reduced. There is a problem that the performance is reduced.
[0009]
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 an ink jet recording paper, and a method of using the resin as a resin that mainly absorbs a solvent of an oil-based ink has been disclosed (for example, , Patent Documents 1 to 6). 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 styrene-butadiene latex containing 20 to 45% by mass of a butadiene component can be used as a binder to improve storage stability in combination with a specific dye. The butadiene ratio was low and the effect was limited. Further, by adding a compound having an aliphatic carbon-carbon double bond group in the molecule (for example, see Patent Document 7), bleeding resistance with time under high temperature and high humidity and discoloration of a formed image due to aging are reduced. However, the effect of preventing gas discoloration was not sufficient.
[0010]
Further, the compound having a carbon-carbon double bond group has a disadvantage that the one decomposed with the lapse of time reacts with other additives and the paper surface is colored (yellowing, etc.).
[0011]
[Patent Document 1]
JP 2000-177234 A
[0012]
[Patent Document 2]
JP 2000-238407 A
[0013]
[Patent Document 3]
JP 2001-205929 A
[0014]
[Patent Document 4]
JP-A-11-165460
[0015]
[Patent Document 5]
JP-A-11-99742
[0016]
[Patent Document 6]
WO 00/041890 pamphlet
[0017]
[Patent Document 7]
JP-A-2002-264478
[0018]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention provides an ink jet recording sheet which has a high effect of preventing discoloration of a printed image, has a good ink absorbency, does not cause cracking at the time of application, and is excellent in preventing coloration (yellowing, etc.) of the paper surface. It is aimed at.
[0019]
[Means for Solving the Problems]
The above object of the present invention has been achieved by the following ink jet recording paper.
[0020]
1. An ink jet method comprising: a porous ink absorbing layer containing a compound having a plurality of non-aromatic carbon-carbon unsaturated bonds in a molecule, an inorganic pigment, a hydrophilic binder and a urea compound on a support. Recording sheet.
[0021]
2. 2. The ink jet recording sheet according to claim 1, wherein the urea compound is urea.
[0022]
3. 3. The compound according to claim 1 or 2, wherein the compound having a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule is a (co) polymer having butadiene or isoprene as a monomer. Ink jet recording paper.
[0023]
4. The compound having a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule is a polybutadiene or polyisoprene having a number average molecular weight in the range of 500 to 10,000. The inkjet recording paper according to any one of claims 1 to 7.
[0024]
5. The ink-jet recording paper according to claim 4, wherein the polybutadiene or polyisoprene has a number average molecular weight in the range of 1500 to 5000.
[0025]
6. The porous ink absorbing layer is composed of two or more layers, and the lower layer contains a compound having a plurality of non-aromatic carbon-carbon unsaturated bonds in a molecule. Item 6. The ink jet recording paper according to any one of items 5.
[0026]
7. 7. The inkjet recording paper according to any one of items 1 to 6, wherein the porous ink absorbing layer contains a polyvalent metal salt.
[0027]
8. 8. The inkjet recording paper according to claim 7, wherein the polyvalent metal salt contains at least one metal selected from aluminum, magnesium, and zirconium.
[0028]
9. 9. The ink jet recording paper according to any one of items 1 to 8, wherein the inorganic pigment is silica fine particles.
[0029]
10. 10. The ink jet recording paper according to any one of items 1 to 9, wherein the porous ink absorbing layer contains a polyamide polyamine-epihalohydrin resin.
[0030]
The present inventors have conducted intensive studies on the above problems, and as a result, in an ink jet recording paper having a porous ink absorbing layer having an inorganic pigment and a hydrophilic binder on a support, the porous ink absorbing layer has an intramolecular molecule. By containing a compound having a plurality of non-aromatic carbon-carbon unsaturated bonds and a urea compound, the ink absorbability is good, the cracking during application (application / drying) is small, and the discoloration prevention effect is high. It has been found that coloring (yellowing, etc.) on the paper surface, which may be caused by a compound having a plurality of non-aromatic carbon-carbon unsaturated bonds, can be suppressed.
[0031]
The inventors presume the reason as follows.
It is well known that in a porous ink absorbing layer using an inorganic pigment, a large number of fine voids are present in the ink absorbing layer, and the discoloration of the dye is caused by mixing an oxidizing gas into the void layer. In the prior application, the carbon-carbon unsaturated bond reacts with the oxidizing gas by containing a compound having a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule in the void layer, and the dye fades. Is clearly specified, but the coloring (yellowing etc.) of the paper surface, which is considered to be caused by the product after the reaction with the carbon-carbon unsaturated bond and the oxidizing gas, is caused by the product after the reaction. It has been found that the urea compound is suppressed by causing a reaction to form another product. Furthermore, it has been found that the anti-fading effect is greater when the compound is a polybutadiene or polyisoprene having a number average molecular weight in the range of 500 to 10,000, especially in the range of 1500 to 5000. Further, a compound having a plurality of carbon-carbon unsaturated bonds may cause a decrease in ink absorbency and cracks during coating (coating / drying). However, by containing a urea compound, the film surface is softened, It has been found that cracking during coating (coating / drying) can be prevented and ink absorbency can be improved. In the case of a structure having two or more layers, the lower layer contains less cracks and improves ink absorbency. Furthermore, it has been found that the polyvalent metal salt has the same effect as the urea compound, and that when used in combination, further coloring (yellowing, etc.) of the paper surface can be prevented, and the ink absorbency can be improved.
[0032]
Hereinafter, the present invention will be described in detail.
The present invention has a porous ink absorbing layer containing a compound having a plurality of non-aromatic carbon-carbon unsaturated bonds in a molecule, an inorganic pigment, a hydrophilic binder and a urea compound on a support. Features.
[0033]
The ink jet recording paper of the present invention is obtained by applying a water-soluble coating solution for forming a porous layer containing a hydrophilic binder and an inorganic pigment on a support to form a porous layer having voids. The porous layer according to the present invention is mainly formed from a pigment and a hydrophilic binder. As the pigment for forming the porous layer, an inorganic pigment or an organic pigment can be used. However, an inorganic pigment is used because high gloss and a high color density can be obtained and fine particles can be easily obtained. 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.
[0034]
In the present invention, from the viewpoint of obtaining high-quality prints on the inkjet recording paper, as the inorganic pigment, silica or alumina is preferable, and alumina, pseudo-boehmite, colloidal silica, or fine particle silica synthesized by a gas phase method is also preferable. Particularly, particulate silica synthesized by a gas phase method is particularly preferable. The silica synthesized by this gas phase method may be one whose surface is modified with aluminum, and the aluminum content of the gas phase silica is 0.05 to 5% by mass relative to silica. Is preferred.
[0035]
Any particle diameter can be used for the inorganic pigment, but the average particle diameter is preferably 1 μm or less. If it exceeds 1 μm, the gloss or the color developability tends to decrease, and therefore, it is preferably 200 nm or less. 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 from the viewpoint of production of the inorganic pigment.
[0036]
The average particle size of the inorganic pigment is obtained by observing the cross section and surface of the porous layer with an electron microscope, calculating 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.
[0037]
The pigment may be present in the porous film as primary particles or as secondary particles or higher-order aggregated particles, but the average particle size in the porous layer when observed with an electron microscope. Refers to the particle size of what forms independent particles.
[0038]
The average primary particle diameter of the pigment must be equal to or less than the average particle diameter observed in the porous film, and the primary particle diameter of the pigment 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.
[0039]
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 needs to form an ink-absorbing layer having sufficient ink-absorbing property and less cracking of the film. The ink-receiving layer contains 5 to 50 g / m ² Is preferable. Furthermore, 10 to 25 g / m ² It is particularly preferred that
[0040]
The hydrophilic binder contained in the porous layer is not particularly limited, and a conventionally known hydrophilic binder can be used. For example, gelatin, polyvinyl pyrrolidone, polyethylene oxide, polyacrylamide, polyvinyl alcohol, and the like can be used. However, polyvinyl alcohol is particularly preferred.
[0041]
Polyvinyl alcohol has an interaction with an inorganic pigment, has a particularly high holding power for the inorganic pigment, is a polymer having a relatively small humidity dependency of 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.
[0042]
As the polyvinyl alcohol obtained by hydrolyzing vinyl acetate, those having an average degree of polymerization of 300 or more are preferably used, and those having an average degree of polymerization of 1,000 to 5,000 are particularly preferably used. -100% is preferable, and 80-99.8% is particularly preferable.
[0043]
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.
[0044]
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.
[0045]
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.
[0046]
Examples of the anion-modified polyvinyl alcohol include, for example, polyvinyl alcohol having an anionic group described in JP-A-1-206088, and vinyl alcohol described in JP-A-61-237681 and JP-A-63-307979 and water-soluble. And a modified polyvinyl alcohol having a water-soluble group described in JP-A-7-285265.
[0047]
Examples of the nonion-modified polyvinyl alcohol include polyvinyl alcohol derivatives described in JP-A-7-9758, in which a polyalkylene oxide group is added to a part of vinyl alcohol, and hydrophobic derivatives described in JP-A-8-25795. And a block copolymer of a vinyl compound having a functional group and vinyl alcohol.
[0048]
Polyvinyl alcohol can be used in combination of two or more kinds, such as a difference in the degree of polymerization and the type of modification. In particular, when polyvinyl alcohol having a polymerization degree of 2,000 or more is used, the polymerization degree is preferably 0.05 to 10% by mass, preferably 0.1 to 5% by mass, based on the inorganic pigment. Addition of 2,000 or more polyvinyl alcohols is preferable because there is no significant thickening.
[0049]
The ratio of the inorganic pigment to the hydrophilic binder in the porous layer is preferably 2 to 20 times 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 by a hydrophilic binder that can be maintained does not occur. This is a factor that can maintain a high ink absorption speed. On the other hand, if this ratio is 20 or less, cracks are less likely to occur when the porous 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.
[0050]
The compound having a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule used in the present invention refers to a compound having at least two ethylenic double bonds or acetylene triple bonds in the molecule. Compound. It is presumed that the non-aromatic carbon-carbon unsaturated bond moiety is effective in preserving the dye. Addition of a large amount of a dye stabilizer to the ink jet recording paper having a porous ink absorbing layer is not preferable from the viewpoint of ink absorbability, because it closes the voids and reduces the void volume. Therefore, it is necessary for the dye stabilizer to have a large effect of stabilizing the dye with a smaller addition amount. Further, it is necessary that the added dye stabilizer itself stably remains in the porous 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 large volatility and a porous layer. Can not remain stable. To reduce volatility, it is necessary to increase the molecular weight or introduce a substituent having high polarity, but simply increasing the molecular weight decreases the ratio of unsaturated bonds per unit mass. This leads to a decrease in void volume, which is not preferable. Therefore, 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 reducing volatility. On the other hand, the dye fixed in the porous layer by the cationic polymer or the like is fixed in a certain area in the porous layer. In extreme cases, the dye is dyed only on the portion near the outermost surface of the porous layer. In order to efficiently increase the preservability of the dye dyed in such a state, the dye stabilizer itself can diffuse to some extent in the porous layer and always be present near the fixed dye. It is desirable. That is, the outermost surface of the porous 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. Due to the action of the dye fixing agent, even when the dye is localized near the outermost layer, if the dye stabilizer can diffuse to some extent in the porous layer, the dye stabilizing effect is obtained from a relatively deep portion of the porous layer. It is possible to diffuse to the outermost layer in a high state, and a higher effect can be obtained. When it has a low molecular weight, the boiling point is preferably at least 200 ° C, more preferably at least 300 ° C. Further, it is preferable from the viewpoint of diffusivity that the property is a liquid or a substance that easily dissolves in water or an ink solvent.
[0051]
Specific examples of the compound having a non-aromatic carbon-carbon unsaturated bond in the molecule include a resin obtained by copolymerizing butadiene alone or another polymerizable monomer, a copolymer obtained by copolymerizing isoprene alone or another polymerizable monomer. Resins, diallyl phthalate resin, unsaturated polyester resin, furan resin, C5 petroleum resin, terpene resin, cyclopentadiene resin, etc .; diallyl phthalate, triallyloxy-1,3,5-triazinepentaerythritol tetra (meta ) Monomers having a plurality of polymerizable groups such as acrylate, trimethylolpropane tri (meth) acrylate, divinylbenzene or the like, or a polymer thereof, an unsaturated fatty acid such as linoleic acid, linolenic acid, arachidonic acid or an esterified product thereof. However, the present invention is not limited to these.
[0052]
Among these compounds, a polymer containing a butadiene or isoprene monomer is preferable, and polybutadiene whose terminal is modified with a hydroxyl group, a carboxyl group, an amino group, maleic anhydride, or the like, or styrene, acrylonitrile, (meth) acrylic acid ester Examples thereof include polybutadiene, polyisoprene, and the like, which are copolymerized with polybutadiene or polyisoprene, among which polybutadiene or polyisoprene having a number average molecular weight in the range of 500 to 10,000 is particularly preferable.
[0053]
Examples of such polybutadiene include Nisso PB (Nippon Soda Co., Ltd.), Nisseki polybutadiene (Nippon Petrochemical Co., Ltd.), Poly-bd (Idemitsu Petrochemical Co., Ltd.), and Hycar (Ube Industries, Ltd.) Polyoil (manufactured by Zeon Corporation), JSR RB (manufactured by JSR Corporation), and polyisoprene such as Poly Ip (manufactured by Idemitsu Petrochemical Co., Ltd.) are commercially available. It is marketed under the product series name and can be easily obtained. Further, among polybutadiene or polyisoprene, the number average molecular weight is preferably in the range of 1500 to 5000, and B-2000 (manufactured by Nippon Soda Co., Ltd.), B-3000 (manufactured by Nippon Soda Co., Ltd.), and the aforementioned Poly Ip (made by Idemitsu Petrochemical Co., Ltd.) and the like.
[0054]
As a method for adding the compound having a non-aromatic carbon-carbon unsaturated bond in the molecule to the porous ink receiving layer, the compound may be added to the coating liquid for forming the ink absorbing layer, or the porous layer may be added. After being applied once, particularly after being applied and dried, it may be supplied to the ink receiving layer by an overcoat method. When added to the coating liquid as in the former case, it is uniformly dissolved in water or an organic solvent or a mixed solvent thereof and added, or dispersed into fine oil droplets (particles) by a method such as emulsification dispersion or wet grinding. Can 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 a single layer, it may be added to that layer. When it is composed of a plurality of layers, it may be added to at least one layer or all layers. It is a preferred embodiment to contain a (co) polymer having butadiene or isoprene as a monomer.
[0055]
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.
[0056]
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 1 m of recording paper. ² Per unit weight of 0.01 g to 3 g. 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 exhibited. From this viewpoint, it is more preferable that the recording paper 1 m ² Per 0.1 to 2 g.
[0057]
(Explanation of polyvalent metals)
The polyvalent metal ion which can be used in the present invention is not particularly limited as long as it is a divalent or higher valent metal ion. Preferred polyvalent metal ions include aluminum ion, magnesium ion, zirconium ion and the like. Is mentioned.
[0058]
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, phosphoric acid water Aluminum, aluminum carbonate, aluminum polysilicate, aluminum formate, aluminum acetate, 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.
[0059]
Among these, aluminum chloride, basic aluminum chloride, aluminum sulfate, basic aluminum sulfate, and basic aluminum sulfate silicate are preferable, and basic aluminum chloride and basic aluminum sulfate are most preferable.
[0060]
Specific examples of salts containing magnesium ions include magnesium fluoride, magnesium acetate, magnesium bromide, magnesium chloride, magnesium formate, magnesium nitrate, magnesium sulfate, magnesium thiocyanate, magnesium thiosulfate, magnesium sulfide, magnesium carbide, phosphoric acid Magnesium is mentioned, and among these, magnesium chloride, magnesium sulfate, and magnesium nitrate are preferable.
[0061]
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 and potassium salts) , 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, ammonium zirconyl acetate, zirconyl lactate, zirconyl citrate, zirconyl stearate, zirconyl phosphate, zirconium oxalate, zirconium isopropylate, zirconium butyrate, zirconium acetylacetonate, acetylacetone zirconium butyrate, stearic acid Zirconium butyrate, zirconium acetate, bis (acetylacetonato) dichlorodi Koniumu, tris (acetylacetonato) chloro zirconium, and the like.
[0062]
Among these compounds, zirconyl carbonate, zirconyl ammonium carbonate, zirconyl acetate, zirconyl nitrate, zirconyl chloride, zirconyl lactate, and zirconyl carbonate, from the viewpoint of more remarkably preventing coloring (yellowing) after printing as the object of the present invention. Zirconyl citrate is preferred, and zirconyl ammonium carbonate, zirconyl chloride and zirconyl acetate are particularly preferred.
[0063]
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 may be applied to the ink receiving layer after the porous layer has been applied once, particularly after the porous layer has been once applied and dried. It may be supplied by a coating method. When the compound containing a polyvalent metal ion is added to the coating liquid for forming the ink absorbing layer as in the former, a method of uniformly dissolving and adding the compound in water, an organic solvent, or a mixed solvent thereof, or wet pulverization such as a sand mill A method of dispersing and adding to fine 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 liquid. When the porous ink receiving layer is formed once and then added by the overcoat method as in the latter, a compound containing a polyvalent metal ion is uniformly dissolved in a solvent and then supplied to the ink receiving layer. Is preferred.
[0064]
These polyvalent metal ions are recorded on a recording paper ² The amount is generally in the range of 0.05 to 20 mmol, preferably 0.1 to 10 mmol.
[0065]
(Urea or its derivative)
The ink jet recording paper of the present invention contains a urea compound in order to improve the coloring (yellowing, etc.) of the paper surface, cracking during coating, and ink absorbency.
[0066]
Examples of the urea compound according to the present invention include compounds having the following structures.
[0067]
Embedded image

[0068]
Where R, R ¹ , R ² , R ³ Represents a hydrogen, an alkyl group, a substituent containing an alkane, a substituent containing an alkene, a substituent containing an aromatic ring such as a cyano group, a nitro group or a phenyl group, or a substituent containing a heterocyclic ring such as imidazole.
[0069]
Specifically, urea, biuret, semicarbazide hydrochloride, biurea, 1-methylurea, 1,1-dimethylurea, 1,3-dimethylurea, 1,1,3-trimethylurea, 1,1,3,3- Tetramethylurea, 1-ethylurea, 1,1-diethylurea, 1,3-diethylurea, 1,1,3-triethylurea, 1- (n-propyl) urea, 1- (n-butyl) urea, 1- (tert-butyl) urea, 1-allyl urea, 1,3-diallyl urea, 1-phenyl urea, 1,1-diphenyl urea, 1,3-diphenyl urea, 1- (o-tolyl) urea, 1 -(M-tolyl) urea, phenylacetylurea, 1- (benzyl) urea, 1-hydroxyurea, 1,3-bis (trimethylsilyl) urea, bis (pentamethylene) urea, 2-imidazolone, barbituric acid, 1 3-dicyclohexylurea, nitrosoureas, di cyan Zia spermidine, hydantoin and the like, may be used in combination of two or more thereof. Of these, urea is particularly preferred.
[0070]
The layer to which the urea compound according to the present invention is added may be added to one layer if the ink receiving layer is a single layer, or to at least one layer or all layers if the ink receiving layer is composed of a plurality of layers. In particular, in the case of two or more layers, it is a preferred embodiment that the upper layer contains a urea compound and the lower layer contains the compound having a plurality of non-aromatic carbon-carbon unsaturated bonds.
[0071]
When the urea compound according to the present invention is added, from the viewpoint of the effects of the present invention, the addition amount per m2 of recording paper is preferably 0.05 to 5 g, and more preferably 0.1 to 1.0 g. . If the amount is less than 0.05 g, the effect is hardly obtained, and if the amount is more than 5 g, the stability of the coating solution is deteriorated.
[0072]
(Explanation of cationic polymer)
In the ink jet recording paper of the invention, it is preferable to use a cationic polymer for the purpose of preventing image bleeding due to storage after recording.
[0073]
Examples of the cationic polymer include polyethyleneimine, polyallylamine, polyvinylamine, dicyandiamide polyalkylene polyamine condensate, polyalkylene polyamine dicyandiamide ammonium salt condensate, dicyandiamide formalin condensate, epichlorohydrin / dialkylamine addition polymer, diallyldimethylammonium chloride Polymer, diallyldimethylammonium chloride / SO ₂ Copolymer, polyvinylimidazole, vinylpyrrolidone / vinylimidazole copolymer, polyvinylpyridine, polyamidine, chitosan, cationized starch, vinylbenzyltrimethylammonium chloride polymer, (2-methacryloyloxyethyl) trimethylammonium chloride polymer, dimethyl Aminoethyl methacrylate polymer; and the like.
[0074]
Further, cationic polymers described in the Chemical Industry Times on August 15 and 25, 1998, and polymeric dye fixing agents described in “Introduction to High Polymer Drugs” published by Sanyo Chemical Industries, Ltd. may be mentioned as examples.
[0075]
As the cationic polymer preferably used in the present invention, a polyamide polyamine-epihalohydrin resin is exemplified. When used in combination with the above compound, the film is prevented from swelling, and the ink absorbency and the effect of preventing discoloration are further improved.
[0076]
Among the polyamide polyamine-epihalohydrin resins, a polyamide polyamine-epichlorohydrin resin is particularly preferred. The amount of the polyamide polyamine-epihalohydrin resin used may vary depending on the amount of the inorganic fine particles and the water-soluble resin in the coating solution, but when used as a recording medium, 0.01 to 1.0 g / m 2 in the ink absorbing layer. ² Is preferably 0.01 to 0.5 g / m ² Is more preferable. 0.01 g / m ² If the amount is less than 1.0 g / m, the effect of improving the ink absorbency and fading is small. ² Exceeding the limit may cause failures such as cracks during coating and drying.
You.
[0077]
The polyamide polyamine-epichlorohydrin resin is also called an epoxidized polyamide resin and is a compound having a structure represented by the following formula.
[0078]
Embedded image

[0079]
In the above formula, n represents the degree of polymerization. The polymerization degree is preferably from 500 to 10,000. If the degree of polymerization is less than 500, it may cause harm to the human body, and if it exceeds 10,000, stability may be lacking.
[0080]
Examples of the method for producing the polyamide polyamine-epihalohydrin resin used in the present invention include a method described in JP-A-6-1842.
[0081]
As the polyamide polyamine-epihalohydrin resin, one type may be used alone, or ones having different degrees of polymerization may be mixed and used in combination. The polyamide polyamine-epichlorohydrin resin may be appropriately synthesized or a commercially available product.
[0082]
(Explanation of hardener)
The ink jet recording paper of the invention preferably contains a water-soluble binder hardener for forming the porous ink receiving layer.
[0083]
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 the water-soluble binder or a compound which promotes the 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-4-hydroxy-1,3,5) -S-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum and the like.
[0084]
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, diboric acid, metaboric acid, tetraboric acid, pentaboric acid and octaboric acid Acids and their salts.
[0085]
Boric acid having a boron atom and a salt thereof as a curing agent may be used alone or as a mixture of two or more. Particularly preferred is a mixed aqueous solution of boric acid and borax.
[0086]
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.
[0087]
The total amount of the curing agent used is preferably 1 to 600 mg per 1 g of the water-soluble binder. Further, the supply amount corresponding to claim 3 is preferably 100 to 600 mg per 1 g of the water-soluble binder.
[0088]
(Description of support)
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.
[0089]
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. In addition, various fibrous substances such as synthetic pulp, synthetic fiber, inorganic fiber and the like can be appropriately used as a raw material, if necessary.
[0090]
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.
[0091]
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 making machine, various coating treatments, or calendar treatment.
[0092]
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 a polyester resin, a diacetate resin, a triacetate resin, an acrylic resin, a polycarbonate resin, a polyvinyl chloride resin, a polyimide resin, a cellophane, a film having a material such as celluloid, and the like. 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.
[0093]
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.
[0094]
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. Further, the ink jet recording paper of the present invention does not necessarily need to be colorless, and may be a colored recording sheet.
[0095]
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.
[0096]
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.
[0097]
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.
[0098]
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 dispersing agent, a softening agent such as quaternary ammonium and the like can be appropriately added.
[0099]
The freeness of the pulp used for papermaking is preferably 200 to 500 ml in accordance with the provisions of CSF, and the fiber length after beating is defined as the mass% of the 24-mesh residue and the residual amount of the 42-mesh residue specified in JIS-P-8207. The sum with the mass% is preferably 30 to 70%. In addition, it is preferable that the mass% of the 4 mesh residue is 20 mass% or less.
[0100]
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.
[0101]
The base paper may be calendered at the papermaking stage or after the papermaking to provide high smoothness. Base paper density is 0.7-1.2g / m ² (JIS-P-8118) is common. Further, the stiffness of the base paper is preferably 20 to 200 g under the conditions specified in JIS-P-8143.
[0102]
A surface sizing agent may be applied to the surface of the base paper. As the surface sizing agent, the same sizing agent as can be added to the base paper can be used.
[0103]
The pH of the base paper is preferably 5 to 9 when measured by the hot water extraction method specified in JIS-P-8113.
[0104]
The polyethylene covering the front and back surfaces of the base paper is mainly low-density polyethylene (LDPE) and / or high-density polyethylene (HDPE), but other LLDPE, polypropylene and the like can also be partially used.
[0105]
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.
[0106]
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 performed to form a matte or silk surface that can be obtained with ordinary photographic printing paper. Can be used in the present invention.
[0107]
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.
[0108]
(Description of additives)
Various additives can be added to the inkjet recording medium of the present invention. For example, polystyrene, polyacrylates, polymethacrylates, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or copolymers thereof, or organic latex fine particles such as melamine resin, cation 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, JP-A-57-87989; Nos. 72785, 61-146591, JP-A-1-95091 and JP-A-3-13376, and the discoloration inhibitors described in JP-A-59-42993, JP-A-59-52689, and JP-A-62-280069. And JP-A-61-242871 and JP-A-4-219266. PH adjusters such as fluorescent whitening agents, sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, defoamers, preservatives, thickeners, antistatic agents, matting agents, etc. Various known additives can be contained.
[0109]
(Description of manufacturing method)
Next, a method for manufacturing the ink jet recording paper of the present invention will be described.
[0110]
As a method for producing an ink jet recording sheet, each constituent layer including an ink absorbing layer can be individually or simultaneously selected from known coating methods as appropriate, applied to 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.
[0111]
When the slide bead coating method is used, the viscosity of each coating solution 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.
[0112]
Further, 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.
[0113]
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 solution 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 preparation, application, and drying of the coating solution. 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 the cooling by a horizontal setting method from the viewpoint of uniformity of the formed coating film.
[0114]
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.
[0115]
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 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, favorable ink absorbency can be achieved.
[0116]
(ink)
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.
[0117]
When performing image recording using the inkjet recording paper of the present invention, a recording method using an aqueous ink is preferably used.
[0118]
The aqueous ink is a recording liquid having the following colorant, solvent, and other additives. As the colorant, a water-soluble dye such as a direct dye, an acid dye, a basic dye, a reactive dye, or a food colorant, or a water-dispersible pigment known by ink jet can be used.
[0119]
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.
[0120]
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.
[0121]
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.
[0122]
【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 the examples, “%” represents mass% unless otherwise specified.
[0123]
<< Preparation of inkjet recording paper >>
(Preparation of dispersion liquid)
(Preparation of silica dispersion (A-1))
75 L of a 20% aqueous solution of a cationic polymer (P-1) was added to 500 L of a 20% silica dispersion (manufactured by Nippon Aerosil Co., Ltd .: Aerosil 300, primary particle diameter: 7 nm), which had been previously uniformly dispersed and adjusted to pH 3.0. 10 L of ethanol, 60 L of an aqueous solution in which 1 g of boric acid and 2 g of borax were added, and 3 kN / cm were applied using a high-pressure homogenizer manufactured by Sanwa Kogyo Co., Ltd. ² , And the whole amount was made up to 650 L with pure water to obtain a substantially transparent silica dispersion liquid (A-1).
[0124]
(Preparation of silica dispersion (A-2))
In the preparation of the silica dispersion (A-1), a silica dispersion (A-2) was prepared in the same manner except that the cationic polymer (P-1) was changed to (P-2). A transparent silica dispersion (A-2) was obtained.
[0125]
Embedded image

[0126]
(Preparation of silica dispersion (A-3))
Preparation of the silica dispersion (A-3) in the same manner as in the preparation of the silica dispersion (A-1) except that Aerosil 300 was replaced by Leolosil QS-20 (manufactured by Tokuyama: primary particle size: 14 nm). Was performed to obtain a substantially transparent silica dispersion liquid (A-3).
[0127]
(Preparation of Oil Dispersion (B-1))
The additives described below were mixed and dispersed with a high-pressure homogenizer, and the whole was finished to 30 L with pure water.
[0128]

(Preparation of Oil Dispersion (B-2))
Solution A and Solution B shown below were each heated and dissolved, and after mixing Solution A and Solution B at 55 ° C., the mixture was emulsified and dispersed with a high-pressure homogenizer, and the whole amount was made up to 30 L with pure water to obtain an oil dispersion (B-2). ) Was prepared.
[0129]

(Preparation of Oil Dispersions (B-3) to (B-6))
In the preparation of the oil dispersion (B-1), instead of polybutadiene (Nippon Soda Co., Ltd .; B-2000), other non-aromatic carbon-carbon unsaturated bonds in the molecule according to the present invention are added. The following oil dispersions were prepared using the same amounts of the compounds having a plurality.
[0130]
Oil dispersion (B-3): Poly Ip (manufactured by Idemitsu Petrochemical Co., Ltd .: number average molecular weight 2500)
Oil dispersion (B-4): B-3000 (manufactured by Nippon Soda Co., Ltd .: number average molecular weight 3000)
Oil dispersion (B-5): Polyoil 110 (manufactured by Zeon Corporation: number average molecular weight 1600)
Oil dispersion (B-6): E-1000-8 (Nippon Petrochemical Co., Ltd .: number average molecular weight 1000)
(Preparation of Oil Dispersions (B-7) and (B-8))
In the preparation of the oil dispersion (B-2), a non-aromatic carbon-carbon unsaturated bond in the molecule according to the present invention is replaced with polybutadiene (Nippon Soda Co., Ltd .; B-1000). The following oil dispersions were prepared using the same amounts of the compounds having a plurality.
[0131]
Oil dispersion (B-7): M-1000-20 (manufactured by Nippon Petrochemical Co., Ltd .: number average molecular weight: about 1000)
Oil dispersion (B-8): Poly-bd R45HT (manufactured by Idemitsu Petrochemical Co., Ltd .: number average molecular weight 2800)
(Preparation of ink absorbing layer coating liquid)
Using the dispersions prepared as described above, the following additives were sequentially mixed with stirring at 40 ° C. to prepare coating solutions.
[0132]

[0133]

[0134]

[0135]

[0136]
Each of the coating solutions prepared above was filtered through a TCPD-30 filter manufactured by Advantech Toyo having a filtration accuracy of 20 μm after preparation, and then filtered through a TCPD-10 filter.
[0137]
[Preparation of recording paper]
(Preparation of Recording Paper 1: Comparative Example)
Each of the coating solutions prepared at 40 ° C. was simultaneously coated with a slide hopper type coater in four layers on a paper support coated on both sides with polyethylene under the following coating conditions to give a wet film thickness.
[0138]
<Wet film thickness>
First layer: 42 μm
Second layer: 39 μm
Third layer: 44 μm
4th layer: 40 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.
[0139]
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 with a polyethylene containing 6% of anatase-type titanium oxide at a thickness of 35 μm and melt-coated, and the thickness of the back side was set on the back side. 40 μm polyethylene was extruded at a thickness of 35 μm and melt coated. After corona discharge on the surface side, polyvinyl alcohol (PVA235 manufactured by Kuraray Co., Ltd.) was applied to the recording medium 1 m. ² The undercoat layer was applied so as to be 0.05 g per unit and corona discharge was applied to the back side. Then, about 0.4 g of a styrene-acrylate latex binder having a Tg of about 80 ° C., an antistatic agent (cationic polymer) 2.) A backing layer containing 0.1 g and 0.1 g of silica of about 2 μm as matting agent was applied.
[0140]
After applying the ink receiving layer coating liquid on the support, the coating liquid was passed through a cooling zone kept at 5 ° C. for 15 seconds to lower the film surface temperature to 13 ° C., and then a plurality of drying zones were provided. After drying by blowing hot air of 20 to 40 ° C. for 6 to 7 minutes, the recording paper 1 was obtained by winding the roll into a roll.
[0141]
(Preparation of recording paper 2: the present invention)
In the preparation of the recording paper 1, 0.5 g / m2 of zircosol ZA (Zirconyl acetate aqueous solution, manufactured by Daiichi Kagaku Kagaku Kogyo KK) was used for the third layer. ² And diluted with water so as to obtain the coating amount. This coating liquid was applied in the same manner to prepare recording paper 2.
[0142]
(Preparation of recording paper 3: the present invention)
In the preparation of the recording paper 2, 36 ml of a 10% aqueous urea solution was added to the coating solution for all layers. This coating liquid was applied in the same manner to prepare recording paper 3.
[0143]
(Preparation of Recording Paper 4: The Present Invention)
In the production of the recording paper 3, except that the oil dispersion (B-3) was used instead of the oil dispersion (B-1) of the coating liquid for the first and second layers, and the zircosol ZA was changed to magnesium sulfate. Similarly, recording paper 4 was produced.
[0144]
(Preparation of recording paper 5: the present invention)
In the production of the recording paper 3, the recording paper 5 was prepared in the same manner except that the oil dispersion (B-1) of the coating liquid for the first and second layers was changed to styrene-butadiene latex (Lx438C, manufactured by Zeon Corporation). Produced.
[0145]
(Preparation of Recording Paper 6: Comparative Example)
In the preparation of the recording paper 1, the oil dispersion (B-1) of the coating liquid for the first layer was not added, and magnesium sulfate was further added at 0.5 g / m 2. ² And diluted with water so as to obtain the coating amount. This coating liquid was applied in the same manner to prepare a recording paper 6.
[0146]
(Preparation of recording paper 7: the present invention)
In the production of the recording paper 1, an oil dispersion (B-4) was used in place of the oil dispersion (B-1) of the coating liquid for the first and second layers, and a polyaluminum chloride compound (multi-layer) was used for the third layer. 0.5g / m of Takibain # 1500 (PAC) manufactured by Kikai Kagaku ² The resulting solution was diluted with water so as to have a coating amount of, and 36 ml of a 10% aqueous urea solution was added to the third and fourth layer coating solutions. This coating liquid was applied in the same manner to prepare a recording paper 7.
[0147]
(Preparation of recording paper 8: the present invention)
Recording paper 8 was produced in the same manner as in the production of recording paper 3 except that the oil dispersion (B-1) of the coating liquid for the first and second layers was changed to (B-5).
[0148]
(Preparation of recording paper 9: the present invention)
Recording paper 9 was produced in the same manner as in the production of recording paper 4 except that the oil dispersion (B-6) was used instead of the oil dispersion (B-3) of the coating liquid for the first and second layers.
[0149]
(Preparation of recording paper 10: the present invention)
The recording paper 10 was produced in the same manner as in the production of the recording paper 7, except that the oil dispersion (B-7) was used instead of the oil dispersion (B-4) of the coating liquid for the first and second layers.
[0150]
(Preparation of recording paper 11: the present invention)
In the production of the recording paper 1, an oil dispersion (B-2) was used in place of the oil dispersion (B-1) of the first and second layer coating liquids, and a 10% aqueous solution of urea was applied to the whole layer coating liquid. 36 ml of each was added. This coating liquid was applied in the same manner to produce a recording paper 11.
[0151]
(Preparation of recording paper 12: the present invention)
The recording paper 12 was produced in the same manner as in the production of the recording paper 11 except that the oil dispersion (B-2) of the coating liquid for the first and second layers was changed to (B-8).
[0152]
(Preparation of recording paper 13: the present invention)
In the production of the recording paper 3, the recording paper 13 was prepared in the same manner except that the oil dispersion (B-2) was used instead of the oil dispersion (B-1) of the coating liquid for the first and second layers. Produced.
[0153]
(Preparation of recording paper 14: the present invention)
In the preparation of the recording paper 3, the silica dispersion (A-2) was replaced with the silica dispersion (A-3), and the coating solution for the third layer, zircosol ZA, was replaced with Takibain # 1500 (PAC, manufactured by Taki Kagaku KK). The recording paper 14 was produced in the same manner as in the above except that the above was replaced.
[0154]
(Preparation of recording paper 15: the present invention)
Recording paper 15 was produced in the same manner as in the production of recording paper 7 except that the cationic polyamide resin (WS552) was omitted.
[0155]
(Preparation of recording paper 16: the present invention)
In the production of the recording paper 3, the recording paper 16 was prepared in the same manner except that the oil dispersion (B-1) was added to the third and fourth layer coating liquids instead of the first and second layer coating liquids. Was prepared.
[0156]
Table 1 shows details of the configuration of each recording sheet.
[Evaluation of each characteristic of recording paper]
The following evaluations were performed for each of the recording sheets prepared above.
[0157]
(Gas discoloration)
For each of the recording sheets prepared above, a solid image of C (cyan) was printed using an inkjet printer PM-970C manufactured by Seiko Epson Corporation, and treated under a 3 ppm ozone atmosphere for 48 hours to evaluate gas discoloration. . The gas discoloration was indicated by the residual ratio of the initial concentration.
[0158]
(Ink absorption)
Blue solid printing was performed using an inkjet printer PM-950C manufactured by Seiko Epson Corporation, and the printed portion was visually observed, and the ink absorbency was evaluated according to the following criteria.
[0159]
A: There is no printing unevenness in the printing portion. (No problem in practical use)
：: Slightly unevenness is observed in the printed portion. (No problem in practical use)
Fair: considerable unevenness in the print area was observed in the printed area. (There is a problem in practical use)
X: The printed portion is almost uneven in a cod-like shape. (There is a problem in practical use)
(crack)
The coated surface was visually observed, and the crack state was evaluated according to the following criteria.
[0160]
○: 0 to 5 cracks of 1 mm or more are observed. (No problem in practical use)
Δ: 6 to 10 cracks of 1 mm or more are observed. (No problem in practical use)
×: 11 or more cracks of 1 mm or more are observed. (There is a problem in practical use)
(Coloring of paper surface (yellowing))
Each recording sheet was treated under a 3 ppm ozone atmosphere for 5 hours, and then stored at 30 ° C. and 80% for 2 weeks. The sheet was visually observed, and the coloring of the sheet was evaluated according to the following criteria.
[0161]
A: The paper surface is not discolored at all. (No problem in practical use)
：: The paper surface is slightly discolored. (No problem in practical use)
Δ: The paper surface is slightly discolored (yellowing). (There is a problem in practical use)
X: The paper surface is almost discolored (yellowing). (There is a problem in practical use)
Table 1 shows the above results.
[0162]
[Table 1]

[0163]
From the results in the above table, it can be seen that the sample having the configuration of the present invention is superior to the comparative example in gas fading, ink absorption, cracking, and coloring of paper (yellowing).
[0164]
【The invention's effect】
According to the present invention, it is possible to provide an ink jet recording sheet which has a high effect of preventing discoloration of a printed image, has a good ink absorbency, does not crack upon application, and is excellent in preventing coloring (yellowing, etc.) on the paper surface.

Claims (10)

Ink jet characterized by having a porous ink absorbing layer containing a compound having a plurality of non-aromatic carbon-carbon unsaturated bonds in a molecule, an inorganic pigment, a hydrophilic binder and a urea compound on a support. Recording sheet. 2. The ink jet recording paper according to claim 1, wherein the urea compound is urea. 3. The compound according to claim 1, wherein the compound having a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule is a (co) polymer having butadiene or isoprene as a monomer. 4. Ink jet recording paper. The compound having a plurality of non-aromatic carbon-carbon unsaturated bonds in the molecule is polybutadiene or polyisoprene having a number average molecular weight in the range of 500 to 10,000. The inkjet recording paper according to any one of claims 1 to 7. The ink-jet recording paper according to claim 4, wherein the number average molecular weight of the polybutadiene or polyisoprene is in the range of 1500 to 5000. 2. The porous ink-absorbing layer is composed of two or more layers, and the lower layer contains a compound having a plurality of non-aromatic carbon-carbon unsaturated bonds in a molecule. 6. The ink jet recording paper according to any one of items 1 to 5. The inkjet recording paper according to any one of claims 1 to 6, wherein the porous ink absorbing layer contains a polyvalent metal salt. The inkjet recording paper according to claim 7, wherein the polyvalent metal salt contains at least one metal selected from aluminum, magnesium, and zirconium. The ink jet recording paper according to any one of claims 1 to 8, wherein the inorganic pigment is silica fine particles. The inkjet recording paper according to any one of claims 1 to 9, wherein the porous ink absorbing layer contains a polyamide polyamine-epihalohydrin resin.