JP4068230B2 - Recording material - Google Patents

Description

（式中、Ｒ¹ 、Ｒ² はそれぞれ独立に水素原子またはメチル基を表す。）
一般式（２）；
【化６】

（式中、Ｒ³ は水素原子またはメチル基を表し、Ｒ⁴ はイソシアネート基を置換基として有するアルキル基である。）
２）支持基体表面にインク吸収層を有するインクジェット用記録材料において，該吸収層が（Ａ）前記一般式（１）で表されるＮ−ビニルカルボン酸アミド系モノマー単位、（Ｂ）前記一般式（２）で表されるモノマー単位、及び（Ｃ）下記一般式（３）及び／または一般式（４）で表されるモノマー単位、を含む共重合体を含有することを特徴とするインクジェット用記録材料、
一般式（３）；
【化７】

（式中、Ｒ⁵ は水素原子またはメチル基を表し、Ｒ⁶ は炭素数１〜１０のアルキレン基、Ｒ⁷ は水素原子またはアルキル基または脂環式炭化水素基を表す。）
一般式（４）；
【化８】

（式中、Ｒ⁵ は水素原子またはメチル基、Ｒ⁶ は炭素数１〜１０のアルキレン基、Ｒ⁷ 、Ｒ⁸ はそれぞれ独立に水素原子またはアルキル基または脂環式炭化水素基、Ｘは任意のアニオンを表す。）
３）支持基体表面にインク吸収層を有するインクジェット用記録材料において，該吸収層が（Ａ）前記一般式（１）で表されるＮ−ビニルカルボン酸アミド系モノマー単位及び（Ｂ）前記一般式（２）で表されるモノマー単位、を含む共重合体及び（Ｄ）正に帯電した超微粒子、を含有することを特徴とするインクジェット用記録材料、
４）支持基体表面にインク吸収層を有するインクジェット用記録材料において，該吸収層が（Ａ）前記一般式（１）で表されるＮ−ビニルカルボン酸アミド系モノマー単位、（Ｂ）前記一般式（２）で表されるモノマー単位、（Ｃ）前記一般式（３）及び／または前記一般式（４）で表されるモノマー単位、を含む共重合体及び（Ｄ）正に帯電した超微粒子、を含有することを特徴とするインクジェット用記録材料、
５）一般式（１）のモノマー単位がＮ−ビニルアセトアミド由来、一般式（２）のモノマー単位が２−ヒドロキシエチルメタクリレート及び２−メタクリロイルオキシエチルイソシアネート由来である上記１）〜４）に記載のインクジェット用記録材料、
６）一般式（４）で表されるモノマー単位がＮ，Ｎ−ジメチルアミノエチルアクリレートの４級化物由来である上記２）、４）及び５）に記載のインクジェット用記録材料。
７）Ｎ−ビニルアセトアミド９０〜２０重量％、２−ヒドロキシエチルメタクリレート１０〜７０重量％、２−メタクリロイルオキシエチルイソシアネート０〜１０重量％及びＮ，Ｎ−ジメチルアミノエチルアクリレートの４級化物０〜３０重量％の割合で共重合して得られる共重合体を含有することを特徴とする上記５）に記載のインクジェット用記録材料、
８）正に帯電した超微粒子が平均粒径０．５μｍ以下のアルミナ、ハイドロタルサイト及びヒドロキシアパタイトの群から選ばれる少なくとも１種である上記３）〜７）に記載のインクジェット用記録材料。なお、本発明でいう「（メタ）アクリ」とは、「アクリ」「メタクリ」のいずれをも指す。
【０００６】
【発明の実施の形態】
本方法において使用される共重合体における上述のモノマー単位のうち、一般式（１）で表されるモノマー単位を与えるための重合性モノマーはＮ−ビニルカルボン酸アミド系モノマーであり、具体例としては例えばＮ−ビニルアセトアミド、Ｎ−ビニルホルムアミド、Ｎ−メチル−Ｎ−ビニルアセトアミド、Ｎ−メチル−Ｎ−ビニルホルムアミドなどが挙げられる。
【０００７】
また一般式（２）で表される（メタ）アクリレート系モノマー単位を与えるために用いる重合性モノマーは（メタ）アクリル酸系モノマーであり、一般式（２）におけるＲ⁴ は水素原子、アルキル基、アリール基、脂環式炭化水素基、アルカリ金属またはアルカリ土類金属を表すが、上記アルキル基、アリール基、及び脂環式炭化水素基は水酸基、アルコキシ基、ハロゲン基及びイソシアネート基から選ばれる置換基を有していてもよい。それらの置換基の中でも、反応性の官能基である水酸基、イソシアネート基を有するモノマーが特に好ましい。具体例としては例えば（メタ）アクリル酸、（メタ）アクリル酸のアンモニウム塩、（メタ）アクリル酸のナトリウム塩、２−メタクリロイルオキシエチルイソシアネート、アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸ｎ−ブチル、（メタ）アクリル酸イソブチルなどの（メタ）アクリル酸エステル、２−ヒドロキシエチル（メタ）アクリレート、２−ヒドロキシプロピル（メタ）アクリレート、２−ヒドロキシブチル（メタ）アクリレートなどが挙げられる。
【０００８】
また一般式（３）で表されるモノマー単位を与えるために用いる重合性モノマーはエステル部位にアミノ基を有する（メタ）アクリル酸エステル系モノマーであり、具体例としては例えば、Ｎ，Ｎ−ジメチルアミノエチル（メタ）アクリレート、Ｎ，Ｎ−ジエチルアミノエチル（メタ）アクリレート、Ｎ，Ｎ−ジメチルアミノプロピル（メタ）アクリレート、Ｎ，Ｎ−ジエチルアミノプロピル（メタ）アクリレートなどが挙げられる。
【０００９】
また一般式（４）で表されるモノマー単位を与えるために用いる重合性モノ
マーはエステル部位に４級化されたアミノ基を有する（メタ）アクリル酸エステル系モノマーであり、その具体例としては例えば、一般式（３）で示されるモノマーであるＮ，Ｎ−ジメチルアミノエチル（メタ）アクリレート、Ｎ，Ｎ−ジエチルアミノエチル（メタ）アクリレート、Ｎ，Ｎ−ジメチルアミノプロピル（メタ）アクリレートあるいはＮ，Ｎ−ジエチルアミノプロピル（メタ）アクリレートなどのアミノ基を有するモノマーを４級化した化合物が挙げられる。一般に４級化反応は上記アミノ基を有するモノマーと塩化メチル、塩化エチル、臭化メチル、臭化エチルなどのハロゲン化アルキルを反応させることで製造される。
本発明で用いる共重合体は、上記重合性モノマーを適宜選択して共重合することによって製造することが出来る。
また一般式（４）で表されるモノマー単位は、一般式（３）で示されるモノマー単位を含む共重合体を上記ハロゲン化アルキルと反応させることによって得ることもできる。
【００１０】
上記一般式（１）、（２）、（３）及び（４）のモノマー単位を与えるために用いるモノマーのうち、特に（１）はＮ−ビニルアセトアミド、（２）は２−ヒドロキシエチルメタクリレート及び／または２−メタクリロイルオキシエチルイソシアネート、（３）はＮ，Ｎ−ジメチルアミノエチルアクリレート、（４）はＮ，Ｎ−ジメチルアミノエチルアクリレートの４級化物を用いることが好ましい。
【００１１】
上記共重合体を製造するための好適な組成比率は重量分率でＮ−ビニルアセトアミド９０〜２０％、更に好ましくは８０〜３０％、２−ヒドロキシエチルメタクリレート１０〜７０％、更に好ましくは２０〜６５％、２−メタクリロイルオキシエチルイソシアネート０〜１０％、更に好ましくは０〜５％、Ｎ，Ｎ−ジメチルアミノエチルアクリレートの４級化物０〜３０％、更に好ましくは５〜２５％である。一般式（１）のモノマー単位が多すぎると染料の定着性、耐水性が悪くなり、少なすぎるとインクの吸収速度および画像の鮮明性が悪くなりいずれも好ましくない。一般式（２）のモノマー単位が多すぎるとインクの吸収速度が悪くなり、少なすぎると耐水性が悪くなりいずれも好ましくない。一般式（３）のモノマー単位が多すぎると画像の鮮明性が悪くなり好ましくない。一般式（４）のモノマー単位が多すぎるとインクの吸収速度、画像の鮮明性が悪くなり、少なすぎると染料の定着性、耐水性が悪くなりいずれも好ましくない。
【００１２】
また上述の重合性モノマーの重合を実施する際には，これらの他に、他の共重合性モノマー、例えば、エチレン、プロピレン、スチレン、アルキルビニルエーテル、バーサチック酸ビニル、無水マレイン酸、クロトン酸、イタコン酸、フマル酸等の不飽和酸及びそのアルキルエステル、Ｎ−ビニルイミダゾール、Ｎ−ビニル−Ｎ−メチルイミダゾールおよびこれらの４級化物を有するモノマーを少量併用することもできる。
【００１３】
また本発明に用いられる正の電荷に帯電した超微粒子は、染料の定着性を良好にする目的で添加されるが、平均粒径が０．５μｍ以下のものが好ましい。これらの要素を満足するものとしてアルミナ、ベーマイト、ハイドロタルサイト、ヒドロキシアパタイトなどが例示され、それらの中でも最大辺が３００ｎｍ以下のアルミナゾルが特に好ましい。
アルミナ（酸化アルミニウム）としては、工業的には、原料となるボーキサイトを熱苛性ソーダで処理するいわゆるバイヤー法と呼ばれる方法で一旦水酸化アルミニウムの結晶を作り、これを焼成して製造したもの、金属アルミニウムペレットを純水中で火花放電させて得られる水酸化アルミニウムを高温で焼成して製造したもの、塩化アルミニウムを気化して酸水素炎中で燃焼加水分解して製造したものなどが挙げられる。
またベーマイトとしては、アルミニウムアルコキサイドの加水分解、水酸化アルミニウムの水熱合成などの方法で製造されたものを用いうる。
ハイドロタルサイトとしては、塩化アルミニウムと塩化マグネシウムとの共沈法などにより製造されたものを用いうる。
さらにアパタイトとしては、固相反応による方法、塩素アパタイト粉末などを原料とする転化反応法、水熱反応法、加水分解法、沈殿反応法などの方法により製造されたものを用いうる。
【００１４】
本発明に用いられる重合体は単独であるいは，他の水溶性あるいは水分散性樹脂と併用して使用することもできる．併用使用できる他の水溶性あるいは水分散性樹脂としては、アルブミン、ゼラチン、カゼイン、でんぷん、アラビアゴム、メチルセルロース、ヒドロキシエチルセルロース、カルボキシメチルセルロース等のセルロース誘導体、ポリアミド樹脂、メラミン樹脂、ポリビニルアルコール、ポリアクリルアミド、ポリビニルピロリドン等のノニオン性水溶性樹脂、ポリアクリル酸ナトリウム、アニオン変性ポリビニルアルコール、アルギン酸ナトリウム、水溶性ポリエステル等のアニオン性水溶性樹脂、ポリエチレンイミン、ポリビニルアミン、ポリアリルアミン、ポリアリルアミンスルホン共重合体あるいはこれらのアンモニウム塩、カチオン化でん粉、カチオン化ポリアクリルアミド、カチオン変性ＰＶＡ、カチオン化ポリアミド樹脂等のカチオン性水溶性樹脂、ＳＢＲラテックス、ＮＢＲラテックス、酢酸ビニル系エマルジョン、エチレン／酢酸ビニル共重合体エマルジョン、アクリルエステル系エマルジョン、塩化ビニル系エマルジョン等の水分散性樹脂が挙げられる。
【００１５】
また本発明において用いられる重合体に、記録特性をより高めるために、無機および／または有機粒子を該吸収層に分散させてもよい。無機粒子として、たとえば、シリカ、クレー、タルク、ケイソウ土、ゼオライト、炭酸カルシウム、硫酸バリウム、ケイ酸アルミ、合成ゼオライト、アルミナ、酸化亜鉛、雲母等が挙げられる。有機粒子としては，例えば、ポリメチルメタクリレート、ポリスチレン，それらの共重合体、ポリ塩化ビニル、ポリエチレン、ポリプロピレン、ポリ塩化ビニリデン、ポリカーボネート等のプラスチックピグメントを好ましく用いることができるが、これらに限定されるものではない。
【００１６】
本発明で用いられる基材としては、紙（上質紙）、塗工紙、和紙、不織布やプラスチックフィルムを使用することができるが、中でもプラスチックフィルムが好ましい。
プラスチックフィルムとしては、ポリエステル、ポリスチレン、ポリ塩化ビニル、ポリメチルメタクリレート、酢酸セルロース、ポリカーボネート、ポリイミド、ポリオレフィン、ポリアミド、ポリエステルアミド、ポリエーテル、ポリアミドイミド、ポリ−ｐ−フェニレンスルフィド、ポリエーテルエステル、ポリアクリル酸エステルなどが好ましい．さらにこれらの共重合体やブレンド物やさらに架橋したものを用いることもできる。
上記基材の中でもポリエステル、好ましくはポリエチレンテレフタレートが機械的特性、作業性などの点から好ましい。
上記ポリエステルとは、多価アルコールと多価カルボン酸とから得られる周知の化合物等であり、具体的には例えば、テレフタル酸、イソフタル酸、ナフタレンジカルボン酸、ビス−α，β−（２−クロルフェノキシ）エタン−４，４’−ジカルボン酸、アジピン酸、セバシン酸等の２官能カルボン酸の少なくとも１種と、エチレングリコール、トリエチレングリコール、テトラメチレングリコール、ヘキサメチレングリコール，デカメチレングリコール等のグリコールの少なくとも１種とを重縮合して得られるポリエステル等を挙げることができる。また、該ポリエステルには本発明の目的を阻害しない範囲内で他種ポリマーをブレンドしたり、共重合してもよいし、酸化防止剤、熱安定剤、滑剤、顔料、紫外線吸収剤などが含まれていてもよい。ポリエステルの固有粘度（２５℃オルトクロルフェノール中での測定値）は０．４〜２．０の範囲が好ましく、更に好ましくは０．５〜１．０の範囲のものが用いられる。
【００１７】
本発明において支持基体表面に用いられる重合体を含有するインク吸収層を形成せしめる方法としては上述の重合体単独水溶液、アルコール溶液およびこれらの混合溶液またはこれと他の水溶性または水分散性樹脂、あるいは重合体と充填材との混合物溶液あるいは溶液分散液をサイズプレス、エアーナイフコーター、ロールコーター、バーコーター、ブレードコーター等通常のコーティング方法によって支持基体の上表面あるいは上表面と下表面との両表面上にコート層を形成せしめる等の方法が使用できる。
また支持基体が紙である場合には抄紙時に上記溶液あるいは分散液を内添する方法も使用しうる。
本発明のインクジェット用記録シート中の前述の重合体の含有量は特に制限はないが、通常０．１〜２００ｇ／ｍ² 、好ましくは１〜１００ｇ／ｍ² が用いられる。
【００１８】
【実施例】
以下に実施例を挙げて本発明をさらに詳しく説明するが、本発明はこれによって限定されるものではない。
なお実施例中の諸物性の測定方法を以下に示す。
（インクジェット記録方法）
日本ゲートウェイ２０００（株）製ＳＯＬＯマルチメディア・ノートブックにキャノン（株）製バブルジェットプリンターＢＪＣ−４１０Ｊを接続し、カラー写真のカラーインクジェット記録を行い、記録特性の評価を行った。
（１）インク吸収速度
インクジェット記録後、一定時間ごとに記録シート上の印字を綿棒でこすり、印字部分が変化しなくなるまでの時間を測定した。
（２）にじみ度
印字ドットの直径を実体顕微鏡で測定し、インク滴の何倍になったかを測定した。倍率が低いほどにじみが少ないことを示す。
（３）透明度
インクジェット用記録シートの非印字部分の可視光線透過率（％）を、５００ｎｍの波長の可視光線を用いて分光光度計で測定した。この透過率をもって透明度とする。透明率が大である程透明性が高いことを示す。
（４）インク吸収層の固定
基材／インク吸収層の密着性は、基材にインク吸収層を塗布した記録シートを２５℃の蒸留水に２４時間浸漬し、付着しているかどうか重量変化で見た。０％が完全固定、１００％が完全溶出を示す。
（５）印刷面の耐水性
インクジェット印刷・乾燥後、印刷面に水滴を落とし、インクの定着性を観察した。
◎：非常に良好（にじみなし）
○：良好（若干にじみ有り）
△：やや劣る（画像判別可能）
×：不良（インクが全部溶出）
【００１９】
（共重合体の製造例）
窒素導入管、温度計と排気管を備えた四つ口の３Ｌセパラブルフラスコ中に、表１に示された各種モノマー（全体で２００ｇ）、脱イオン水２０００ｇを仕込み、２００ｍｌ／分で系内に窒素を約１時間導入して脱気した。その後シクロヘキサン１００ｍｌに溶解した２，２’−アゾビス（２，４−ジメチル−４−メトキシバレロニトリル）３ｇを加え、系内の温度を３０℃に昇温し３００ｒｐｍで６時間撹拌した。放冷後内容物をアセトン洗浄し、固形分を６０℃、６時間真空乾燥した。得られた重合体中の、各モノマー由来のユニットの比率を、 ¹Ｈ−ＮＭＲにより求めた。得られた結果を表２に示した。こうして得られたポリマーの乾燥粒子を以下の工程で使用した。
【００２０】
（実施例１）
厚さ１００μｍ、透明度９８％のポリエステルシート上に、表１の製造例１に示すモノマーを製造例に従ってラジカル重合して得られた、表２の製造例１の組成の重合体の５％水溶液を、乾燥後の膜厚が２０μｍとなるよう塗布し乾燥してインクジェット記録用シートを得た。このシートのインク吸収速度、にじみ度、透明度、インク吸収層の固定、印刷面の耐水性の評価結果を表４に示す。ポリエステルシートとインク受容層との密着性が悪いときは、アンカーコート剤により密着強度を増すことができる。
【００２１】
（実施例２〜７）
実施例１と同様にして、表２の製造例２〜７の組成の重合体を用いて、製造例２〜７の数字に対応する実施例２〜７を行った。評価結果を表４に示す。ポリエステルシートとインク受容層との密着性が悪いときは、アンカーコート剤により密着強度を増すことができる。
【００２２】
（比較例１）
実施例１と同様にして、表２の比較製造例１の組成の重合体を用いて、比較例１の試験を行った。評価結果を表４に示す。ポリエステルシートとインク受容層との密着性が悪いときは、アンカーコート剤により密着強度を増すことができる。
【００２３】
（実施例８〜１４）
厚さ１００μｍ、透明度９８％のポリエステルシート上に、表１に示すモノマーを製造例に従ってラジカル重合して得られた共重合体及び表３の超微粒子を含む５％水溶液を乾燥後の膜厚が２０μｍとなるよう塗布し、乾燥してインクジェット記録用シートを得た。このシートのインク吸収速度、にじみ度、透明度、インク吸収層の固定、印刷面の耐水性の評価結果を表４に示す。ポリエステルシートとインク受容層との密着性が悪いときは、アンカーコート剤により密着強度を増すことができる。
【００２４】
【表１】

ＮＶＡ ：Ｎ−ビニルアセトアミド
ＨＥＭＡ：２−ヒドロキシエチルメタクリレート
ＭＯＩ ：オキシムブロック２−メタクリロイルオキシエチルイソシアネート（昭和電工製 商品名：カレンズＭＯＩ）
ＤＭＡＥＡ：Ｎ，Ｎ−ジメチルアミノエチルアクリレートの塩化メチレンによ
る４級化物
（製造例７、１１はＭＯＩに変えてアクリル酸を使用）
【００２５】
【表２】

※製造例７、１１はＭＯＩではなく、アクリル酸由来のユニットの重量％。
【００２６】
【表３】

※ 重量部は、共重合体１００重量部に対する添加超微粒子の重量部
【００２７】
【表４】

【００２８】
【発明の効果】
本発明の被記録材料は、支持基体表面のインク吸収層が、インクの吸収特性の良好なＮ−ビニルカルボン酸系モノマー単位及び基材に固定化するための機能を有したモノマー単位とを含む共重合体を含有するものであり、インクの吸収性、記録画像の鮮明性、耐水性及び染料定着性に優れた記録材料である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a recording material, and more particularly to a recording material for an ink jet printer having a clear image color tone, excellent ink absorbability, and excellent water resistance and abrasion resistance.
[0002]
[Prior art]
The inkjet recording system is being applied to facsimiles, various printers, and the like because of its low noise during printing, easy colorization, and high-speed recording. Ink jet printers use ink that is difficult to dry in order to prevent nozzle clogging, and the ink components are generally those in which a binder, a dye, a solvent, an additive, and the like are dissolved in water. Accordingly, it is necessary to use a recording material having good absorbency, and conventionally, ordinary paper has been used. However, with the improvement of the performance of an ink jet recording machine such as high speed recording or multi-color printing, more advanced characteristics have been required for ink jet recording sheets. That is, the ink absorption speed is large, the diameter of the ink dots is not larger than necessary, and the shape of the ink dots is close to a perfect circle.
[0003]
[Problems to be solved by the invention]
Advanced properties are required for ink jet recording materials. In order to improve the ink absorbability of the base material, for example, a water-soluble polymer receiving layer such as polyvinyl alcohol, starch, gelatin, cellulose derivatives such as hydroxylethylcellulose and methylcellulose, polyacrylic acid, polymethacrylic acid and salts thereof is provided. However, even though the conventional receiving layer satisfies the ink absorbability, the recorded image is poor in sharpness and water resistance, and the receiving layer and the recording part are dissolved in water and the recorded image disappears. In addition, there are problems that the surface is sticky and the recorded image is blurred, or that when the sheets are laminated, blocking occurs. In recent years, as shown in Japanese Patent Publication No. 7-29480, a proposal has been made that a nonionic hydrophilic polymer can be used to provide a polymer receiving layer excellent in ink absorbability and recorded image clarity. However, the water resistance has not yet reached a satisfactory level. An object of the present invention is to solve such problems and to provide an ink jet recording material which is excellent in ink absorbability and sharpness of a recorded image, and excellent in dye fixing property and water resistance.
[0004]
[Means for Solving the Problems]
As a result of diligent investigations to solve the above-described problems and to achieve the above-described object, the present inventors have found that in the recording material having an ink-absorbing layer on the surface of the supporting substrate, the absorbing layer is (A) ink absorption characteristics. For N-vinyl carboxylic acid monomer unit having good quality and (B) a polymer containing a (meth) acrylate monomer unit having a function for immobilization on a substrate as an essential component The present inventors have found that the recording material is an ink jet recording material that has excellent ink absorbability, excellent recorded image sharpness, and excellent dye fixing properties, and has completed the present invention.
[0005]
That is, the present invention relates to the following matters.
1) In an inkjet recording material having an ink absorbing layer on the surface of a supporting substrate, the absorbing layer is (A) an N-vinylcarboxylic acid amide monomer unit represented by the following general formula (1) and (B) the following general formula. An ink jet recording material comprising a copolymer containing a monomer unit represented by (2),
General formula (1);
[Chemical formula 5]

(In the formula, R ¹ and R ² each independently represents a hydrogen atom or a methyl group.)
General formula (2);
[Chemical 6]

(In the formula, R ³ represents a hydrogen atom or a methyl group, and R ⁴ is an alkyl group having an isocyanate group as a substituent .)
2) In an inkjet recording material having an ink absorbing layer on the surface of a supporting substrate, the absorbing layer is (A) an N-vinylcarboxylic acid amide monomer unit represented by the general formula (1), and (B) the general formula. monomer unit represented by (2), and (C) the following general formula (3) and / or the general formula jet characterized by containing a copolymer comprising monomer units represented by (4) Recording material,
General formula (3);
[Chemical 7]

(In the formula, R ⁵ represents a hydrogen atom or a methyl group, R ⁶ represents an alkylene group having 1 to 10 carbon atoms, and R ⁷ represents a hydrogen atom, an alkyl group, or an alicyclic hydrocarbon group .)
General formula (4);
[Chemical 8]

(In the formula, R ⁵ is a hydrogen atom or a methyl group, R ⁶ is an alkylene group having 1 to 10 carbon atoms, R ⁷ and R ⁸ are each independently a hydrogen atom, an alkyl group or an alicyclic hydrocarbon group , and X is arbitrary. Represents an anion of
3) In an inkjet recording material having an ink absorbing layer on the surface of a supporting substrate, the absorbing layer is (A) an N-vinylcarboxylic acid amide monomer unit represented by the general formula (1) and (B) the general formula. An inkjet recording material comprising: a copolymer containing the monomer unit represented by (2); and (D) a positively charged ultrafine particle,
4) In an inkjet recording material having an ink absorbing layer on the surface of a supporting substrate, the absorbing layer is (A) an N-vinylcarboxylic acid amide monomer unit represented by the general formula (1), and (B) the general formula. A monomer unit represented by (2), (C) a copolymer comprising the monomer unit represented by the general formula (3) and / or the general formula (4), and (D) positively charged ultrafine particles. A recording material for inkjet , comprising:
5) The monomer unit of the general formula (1) is derived from N-vinylacetamide, and the monomer unit of the general formula (2) is derived from 2-hydroxyethyl methacrylate and 2-methacryloyloxyethyl isocyanate. Inkjet recording material,
6) The inkjet recording material according to 2), 4) and 5) above, wherein the monomer unit represented by the general formula (4) is derived from a quaternized product of N, N-dimethylaminoethyl acrylate.
7) N-vinylacetamide 90 to 20% by weight, 2-hydroxyethyl methacrylate 10 to 70% by weight, 2-methacryloyloxyethyl isocyanate 0 to 10% by weight and N, N-dimethylaminoethyl acrylate quaternized compound 0 to 30 The inkjet recording material according to 5) above, comprising a copolymer obtained by copolymerization in a proportion by weight,
8 ) The inkjet recording material according to 3) to 7 ), wherein the positively charged ultrafine particles are at least one selected from the group consisting of alumina, hydrotalcite and hydroxyapatite having an average particle size of 0.5 μm or less. In the present invention, “(meth) acryl” refers to both “acryl” and “methacryl”.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Among the above-described monomer units in the copolymer used in the present method, the polymerizable monomer for giving the monomer unit represented by the general formula (1) is an N-vinylcarboxylic acid amide monomer. Examples thereof include N-vinylacetamide, N-vinylformamide, N-methyl-N-vinylacetamide , N-methyl-N-vinylformamide and the like.
[0007]
The polymerizable monomer used to give the (meth) acrylate monomer unit represented by the general formula (2) is a (meth) acrylic acid monomer, and R ⁴ in the general formula (2) is a hydrogen atom or an alkyl group. Represents an aryl group, an alicyclic hydrocarbon group, an alkali metal or an alkaline earth metal, and the alkyl group, aryl group and alicyclic hydrocarbon group are selected from a hydroxyl group, an alkoxy group, a halogen group and an isocyanate group. It may have a substituent. Among these substituents, monomers having reactive functional groups such as hydroxyl groups and isocyanate groups are particularly preferable. Specific examples include (meth) acrylic acid, ammonium salt of (meth) acrylic acid, sodium salt of (meth) acrylic acid, 2-methacryloyloxyethyl isocyanate, methyl acrylate, ethyl (meth) acrylate, (meth) (Meth) acrylic acid ester such as n-butyl acrylate, isobutyl (meth) acrylate , 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, etc. It is done.
[0008]
The polymerizable monomer used to give the monomer unit represented by the general formula (3) is a (meth) acrylic acid ester monomer having an amino group at the ester site. Specific examples thereof include N, N-dimethyl. aminoethyl (meth) acrylate, N, N- diethylaminoethyl (meth) acrylate, N, N- dimethylacetamide Minopuropiru (meth) acrylate, N, etc. N- diethylaminopropyl (meth) acrylate.
[0009]
Moreover, the polymerizable monomer used to give the monomer unit represented by the general formula (4) is a (meth) acrylic acid ester-based monomer having an amino group quaternized at the ester site. N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate or N, N which is a monomer represented by the general formula (3) -The compound which quaternized the monomer which has amino groups, such as diethylaminopropyl (meth) acrylate, is mentioned. In general, the quaternization reaction is produced by reacting the above monomer having an amino group with an alkyl halide such as methyl chloride, ethyl chloride, methyl bromide or ethyl bromide.
The copolymer used in the present invention can be produced by appropriately selecting the above polymerizable monomers and copolymerizing them.
The monomer unit represented by the general formula (4) can also be obtained by reacting a copolymer containing the monomer unit represented by the general formula (3) with the alkyl halide.
[0010]
Among the monomers used to give the monomer units of the above general formulas (1), (2), (3) and (4), in particular (1) is N-vinylacetamide, (2) is 2-hydroxyethyl methacrylate and It is preferable to use 2-methacryloyloxyethyl isocyanate, (3) N, N-dimethylaminoethyl acrylate, and (4) quaternized N, N-dimethylaminoethyl acrylate.
[0011]
A suitable composition ratio for producing the copolymer is N-vinylacetamide 90 to 20%, more preferably 80 to 30%, 2-hydroxyethyl methacrylate 10 to 70%, more preferably 20 to 20% by weight. 65%, 2-methacryloyloxyethyl isocyanate 0 to 10%, more preferably 0 to 5%, quaternized product of N, N-dimethylaminoethyl acrylate 0 to 30%, more preferably 5 to 25%. When the amount of the monomer unit of the general formula (1) is too large, the fixing property and water resistance of the dye are deteriorated, and when the amount is too small, the ink absorption speed and the sharpness of the image are deteriorated. When the amount of the monomer unit of the general formula (2) is too large, the ink absorption rate is deteriorated, and when the amount is too small, the water resistance is deteriorated. When there are too many monomer units of General formula (3), the clearness of an image will worsen and it is unpreferable. If the amount of the monomer unit of the general formula (4) is too large, the ink absorption rate and the sharpness of the image are deteriorated. If the amount is too small, the dye fixing property and water resistance are deteriorated, which is not preferable.
[0012]
In addition, when carrying out the polymerization of the above-described polymerizable monomer, in addition to these, other copolymerizable monomers such as ethylene, propylene, styrene, alkyl vinyl ether, vinyl versatate, maleic anhydride, crotonic acid, itacone A small amount of an unsaturated acid such as acid or fumaric acid and an alkyl ester thereof, N-vinylimidazole, N-vinyl-N-methylimidazole, or a monomer having these quaternized products can be used in combination.
[0013]
The ultrafine particles charged to a positive charge used in the present invention are added for the purpose of improving the fixability of the dye, but those having an average particle size of 0.5 μm or less are preferred. Alumina, boehmite, hydrotalcite, hydroxyapatite and the like are exemplified as satisfying these elements, and among these, alumina sol having a maximum side of 300 nm or less is particularly preferable.
Alumina (aluminum oxide) is industrially produced by first producing aluminum hydroxide crystals by a so-called Bayer method in which bauxite as a raw material is treated with hot caustic soda, and then firing it. Examples include those prepared by firing pellets in spark water in pure water and calcining aluminum hydroxide at a high temperature, and those obtained by vaporizing aluminum chloride and combustion hydrolysis in an oxyhydrogen flame.
Further, as boehmite, one produced by a method such as hydrolysis of aluminum alkoxide or hydrothermal synthesis of aluminum hydroxide can be used.
As hydrotalcite, what was manufactured by the coprecipitation method of aluminum chloride and magnesium chloride etc. can be used.
Furthermore, as the apatite, those produced by a solid phase reaction method, a conversion reaction method using a chlorapatite powder or the like as a raw material, a hydrothermal reaction method, a hydrolysis method, a precipitation reaction method, or the like can be used.
[0014]
The polymer used in the present invention can be used alone or in combination with other water-soluble or water-dispersible resins. Other water-soluble or water-dispersible resins that can be used in combination include albumin, gelatin, casein, starch, gum arabic, cellulose derivatives such as methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, polyamide resins, melamine resins, polyvinyl alcohol, polyacrylamide, Nonionic water-soluble resin such as polyvinylpyrrolidone, anionic water-soluble resin such as sodium polyacrylate, anion-modified polyvinyl alcohol, sodium alginate, water-soluble polyester, polyethyleneimine, polyvinylamine, polyallylamine, polyallylamine sulfone copolymer or These ammonium salts, cationized starch, cationized polyacrylamide, cation-modified PVA, cationized polyamide resin, etc. On water-soluble resin, SBR latex, NBR latex, vinyl acetate emulsion, ethylene / vinyl acetate copolymer emulsion, an acrylic ester emulsion, and water-dispersible resins such as vinyl chloride emulsion.
[0015]
In the polymer used in the present invention, inorganic and / or organic particles may be dispersed in the absorption layer in order to further improve the recording characteristics. Examples of inorganic particles include silica, clay, talc, diatomaceous earth, zeolite, calcium carbonate, barium sulfate, aluminum silicate, synthetic zeolite, alumina, zinc oxide, mica and the like. As the organic particles, for example, plastic pigments such as polymethyl methacrylate, polystyrene, copolymers thereof, polyvinyl chloride, polyethylene, polypropylene, polyvinylidene chloride, and polycarbonate can be preferably used, but are not limited thereto. is not.
[0016]
As the base material used in the present invention, paper (quality paper), coated paper, Japanese paper, non-woven fabric and plastic film can be used, and among them, a plastic film is preferable.
Plastic films include polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate, cellulose acetate, polycarbonate, polyimide, polyolefin, polyamide, polyester amide, polyether, polyamide imide, poly-p-phenylene sulfide, polyether ester, polyacrylic. Acid esters are preferred. Furthermore, these copolymers, blends, and further crosslinked ones can also be used.
Among the above-mentioned base materials, polyester, preferably polyethylene terephthalate is preferable from the viewpoints of mechanical properties and workability.
The polyester is a known compound obtained from a polyhydric alcohol and a polyvalent carboxylic acid. Specifically, for example, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, bis-α, β- (2-chloro). Phenoxy) ethane-4,4'-dicarboxylic acid, adipic acid, at least one bicarboxylic acid such as sebacic acid, and glycols such as ethylene glycol, triethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol And polyesters obtained by polycondensation of at least one of the above. Further, the polyester may be blended or copolymerized with other types of polymers within the range not impairing the object of the present invention, and includes an antioxidant, a heat stabilizer, a lubricant, a pigment, an ultraviolet absorber, and the like. It may be. The intrinsic viscosity of the polyester (measured value in 25 ° C. orthochlorophenol) is preferably in the range of 0.4 to 2.0, more preferably in the range of 0.5 to 1.0.
[0017]
Examples of a method for forming an ink absorbing layer containing a polymer used on the surface of a support substrate in the present invention include the above-mentioned polymer single aqueous solution, alcohol solution and mixed solution thereof, and other water-soluble or water-dispersible resins. Alternatively, the polymer or filler mixture solution or solution dispersion is applied to the upper surface or both the upper and lower surfaces of the supporting substrate by a normal coating method such as size press, air knife coater, roll coater, bar coater, blade coater, etc. A method such as forming a coat layer on the surface can be used.
When the supporting substrate is paper, a method of internally adding the above solution or dispersion during paper making can also be used.
The content of the polymer described above in the inkjet recording sheet of the present invention is not particularly limited, usually 0.1 to 200 g / m ^2, preferably from 1 to 100 g / m ² is used.
[0018]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
In addition, the measuring method of various physical properties in an Example is shown below.
(Inkjet recording method)
A bubble jet printer BJC-410J manufactured by Canon Inc. was connected to a SOLO multimedia notebook manufactured by Japan Gateway 2000 Co., Ltd., and color ink jet recording of color photographs was performed, and the recording characteristics were evaluated.
(1) Ink absorption speed After ink jet recording, the print on the recording sheet was rubbed with a cotton swab at regular intervals, and the time until the printed portion was not changed was measured.
(2) Bleeding The diameter of the printed dots was measured with a stereomicroscope to determine how many times the ink droplets were formed. A lower magnification indicates less bleeding.
(3) Transparency The visible light transmittance (%) of the non-printed portion of the inkjet recording sheet was measured with a spectrophotometer using visible light having a wavelength of 500 nm. This transmittance is defined as transparency. It shows that transparency is so high that a transparency rate is large.
(4) Fixing of ink absorbing layer: Adhesion between the ink absorbing layer and the ink absorbing layer was determined by immersing a recording sheet coated with the ink absorbing layer on the substrate in distilled water at 25 ° C. for 24 hours and changing the weight. saw. 0% indicates complete fixation and 100% indicates complete elution.
(5) Water-resistant inkjet printing on the printed surface After drying, water droplets were dropped on the printed surface, and the ink fixing property was observed.
◎: very good
○: Good (there is slight blurring)
△: Slightly inferior (image discrimination is possible)
X: Defect (all ink is eluted)
[0019]
(Example of copolymer production)
Various monomers shown in Table 1 (200 g in total) and 2000 g of deionized water were charged into a four-necked 3 L separable flask equipped with a nitrogen inlet tube, a thermometer and an exhaust pipe, and the system was charged at 200 ml / min. Was degassed by introducing nitrogen for about 1 hour. Thereafter, 3 g of 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile) dissolved in 100 ml of cyclohexane was added, the temperature in the system was raised to 30 ° C., and the mixture was stirred at 300 rpm for 6 hours. After standing to cool, the contents were washed with acetone, and the solid content was vacuum dried at 60 ° C. for 6 hours. The ratio of the units derived from each monomer in the obtained polymer was determined by ¹ H-NMR. The obtained results are shown in Table 2. The polymer dry particles thus obtained were used in the following steps.
[0020]
Example 1
A 5% aqueous solution of a polymer having the composition of Production Example 1 in Table 2 obtained by radical polymerization of a monomer shown in Production Example 1 in Table 1 on a polyester sheet having a thickness of 100 μm and a transparency of 98% according to the Production Example. The ink-jet recording sheet was obtained by applying and drying so that the film thickness after drying was 20 μm. Table 4 shows the evaluation results of the ink absorption speed, the degree of bleeding, the transparency, the fixing of the ink absorption layer, and the water resistance of the printed surface of this sheet. When the adhesion between the polyester sheet and the ink receiving layer is poor, the adhesion strength can be increased by the anchor coating agent.
[0021]
(Examples 2 to 7)
In the same manner as in Example 1, Examples 2 to 7 corresponding to the numbers in Production Examples 2 to 7 were performed using the polymers having the compositions of Production Examples 2 to 7 in Table 2. The evaluation results are shown in Table 4. When the adhesion between the polyester sheet and the ink receiving layer is poor, the adhesion strength can be increased by the anchor coating agent.
[0022]
(Comparative Example 1)
In the same manner as in Example 1, the test of Comparative Example 1 was performed using the polymer having the composition of Comparative Production Example 1 shown in Table 2. The evaluation results are shown in Table 4. When the adhesion between the polyester sheet and the ink receiving layer is poor, the adhesion strength can be increased by the anchor coating agent.
[0023]
(Examples 8 to 14)
The thickness after drying a 5% aqueous solution containing a copolymer obtained by radical polymerization of the monomers shown in Table 1 on a polyester sheet having a thickness of 100 μm and transparency of 98% according to the production example and the ultrafine particles shown in Table 3 is as follows. It was applied to a thickness of 20 μm and dried to obtain an inkjet recording sheet. Table 4 shows the evaluation results of the ink absorption speed, the degree of bleeding, the transparency, the fixing of the ink absorption layer, and the water resistance of the printed surface of this sheet. When the adhesion between the polyester sheet and the ink receiving layer is poor, the adhesion strength can be increased by the anchor coating agent.
[0024]
[Table 1]

NVA: N-vinylacetamide HEMA: 2-hydroxyethyl methacrylate MOI: oxime block 2-methacryloyloxyethyl isocyanate (trade name: Karenz MOI manufactured by Showa Denko)
DMAEA: quaternized product of N, N-dimethylaminoethyl acrylate with methylene chloride (Production Examples 7 and 11 use acrylic acid instead of MOI)
[0025]
[Table 2]

* Production Examples 7 and 11 are not MOI but weight% of units derived from acrylic acid.
[0026]
[Table 3]

* The parts by weight are parts by weight of the added ultrafine particles with respect to 100 parts by weight of the copolymer.
[Table 4]

[0028]
【The invention's effect】
In the recording material of the present invention, the ink absorption layer on the surface of the support substrate includes an N-vinylcarboxylic acid monomer unit having good ink absorption characteristics and a monomer unit having a function for immobilization on the substrate. The recording material contains a copolymer and is excellent in ink absorptivity, sharpness of recorded images, water resistance and dye fixing properties.

Claims (8)

In an ink jet recording material having an ink absorbing layer on the surface of a supporting substrate, the absorbing layer comprises (A) an N-vinylcarboxylic acid amide monomer unit represented by the following general formula (1) and (B) the following general formula (2 ink-jet recording material characterized by containing a copolymer comprising monomer units represented by).
General formula (1);

(Wherein R ¹ and R ² each independently represents a hydrogen atom or a methyl group.)
General formula (2);

(In the formula, R ³ represents a hydrogen atom or a methyl group, and R ⁴ is an alkyl group having an isocyanate group as a substituent .) In an inkjet recording material having an ink absorbing layer on the surface of a supporting substrate, the absorbing layer is (A) an N-vinylcarboxylic acid amide monomer unit represented by the general formula (1), and (B) the general formula (2). monomer unit represented by), and (C) the following general formula (3) and / or formula (inkjet recording material characterized by containing a copolymer comprising a monomer unit represented by 4).
General formula (3);

(In the formula, R ⁵ represents a hydrogen atom or a methyl group, R ⁶ represents an alkylene group having 1 to 10 carbon atoms, and R ⁷ represents a hydrogen atom, an alkyl group, or an alicyclic hydrocarbon group .)
General formula (4);

(In the formula, R ⁵ is a hydrogen atom or a methyl group, R ⁶ is an alkylene group having 1 to 10 carbon atoms, R ⁷ and R ⁸ are each independently a hydrogen atom, an alkyl group or an alicyclic hydrocarbon group , and X is arbitrary. Represents an anion of In an ink jet recording material having an ink absorbing layer on the surface of a supporting substrate, the absorbing layer comprises (A) an N-vinylcarboxylic acid amide monomer unit represented by the general formula (1) and (B) the general formula (2). ink-jet recording material characterized by containing the copolymer and (D) positively charged ultra-fine particles comprise monomeric units, the represented by). In an inkjet recording material having an ink absorbing layer on the surface of a supporting substrate, the absorbing layer is (A) an N-vinylcarboxylic acid amide monomer unit represented by the general formula (1), and (B) the general formula (2). And (C) a copolymer containing the monomer unit represented by the general formula (3) and / or the general formula (4), and (D) a positively charged ultrafine particle. An ink jet recording material comprising: The monomer unit of general formula (1) is derived from N-vinylacetamide, and the monomer unit of general formula (2) is derived from 2-hydroxyethyl methacrylate and 2-methacryloyloxyethyl isocyanate. Inkjet recording material. The ink jet recording material according to claim 2, 4 or 5, wherein the monomer unit represented by the general formula (4) is derived from a quaternized product of N, N-dimethylaminoethyl acrylate. N-vinylacetamide 90-20% by weight, 2-hydroxyethyl methacrylate 10-70% by weight, 2-methacryloyloxyethyl isocyanate 0-10% by weight and N, N-dimethylaminoethyl acrylate quaternized 0-30% by weight The inkjet recording material according to claim 5, comprising a copolymer obtained by copolymerization at a ratio of The inkjet recording material according to any one of claims 3 to 7 , wherein the positively charged ultrafine particles are at least one selected from the group consisting of alumina, hydrotalcite and hydroxyapatite having an average particle size of 0.5 µm or less.