JP3718150B2 - Coating agent for ink jet recording paper and ink jet recording paper coated with the same - Google Patents

Description

【００１９】
によって求められる。
【００２０】
本発明においては、インクジェット記録紙用塗工剤として、分岐密度が１０００原子量当たり０．０８〜０．２５であるカチオン性ウレタンプレポリマーをポリアミン化合物で鎖伸長したカチオン性水系ポリウレタン樹脂を使用することにより、インク定着性（乾燥性）、耐水性が優れることはもとより、耐擦過性、印刷時の寸法安定性、耐熱性、耐溶剤性、無機充填剤に対するバインダー能力が優れることが見出された。すなわち、分岐密度が１０００原子量当たり０．０８〜０．２５であるカチオン性ウレタンプレポリマーをポリアミン化合物で鎖伸長したカチオン性水系ポリウレタン樹脂を塗工したインクジェット記録紙は、塗工面を擦っても傷がつきにくい（耐擦過性がすぐれる）、水性インクで印刷した場合でも記録紙が延びることがない（印刷時の寸法安定性が優れる）、印刷物を高温で保存しても画像が変色することがない（耐熱性がすぐれる）、印刷面を有機溶剤で擦っても画像の脱落が生じない（耐溶剤性が優れる）、無機充填剤を併用する場合においても、塗工性よく均質な塗工層を形成できる（無機充填剤に対するバインダー能力が優れる）という優れた効果が発揮される。
【００２１】
分岐密度が０．０８未満では、耐擦過性、印刷時の寸法安定性、耐熱性が劣る。分岐密度が０．２５を超えると、ポリウレタン樹脂の最低造膜温度が高くなりすぎ、加工上好ましくない。
【００２２】
また、優れた耐擦過性、印刷時の安定性、耐熱性、耐溶剤性を得るためには、カチオン性水系ポリウレタン樹脂の重量平均分子量が１０万〜１００万であるのが好ましく、より好ましくは４０万〜１００万である。カチオン性水系ポリウレタン樹脂の重量平均分子量が前記範囲未満では、耐擦過性、印刷時の安定性、耐熱性、耐溶剤性が劣る傾向にある。一方、重量平均分子量が前記範囲をこえると、ポリウレタン樹脂の造膜温度が高くなり、加工性が劣るようになる傾向がある。
【００２３】
本発明で使用する有機ポリイソシアネート（Ａ）としては、たとえば、２，４−トリレンジイソシアネート、２，６−トリレンジイソシアネート、ｍ−フェニレンジイソシアネート、ｐ−フェニレンジイソシアネート、４，４′−ジフェニルメタンジイソシアネート、２，４′−ジフェニルメタンジイソシアネート、２，２′−ジフェニルメタンジイソシアネート、３，３′−ジメチル−４，４′−ビフェニレンジイソシアネート、３，３′−ジクロロ−４，４′−ビフェニレンジイソシアネート、１，５−ナフタレンジイソシアネート、１，５−テトラヒドロナフタレンジイソシアネート、テトラメチレンジイソシアネート、１，６−ヘキサメチレンジイソシアネート、ドデカメチレンジイソシアネート、トリメチルヘキサメチレンジイソシアネート、１，３−シクロヘキシレンジイソシアネート、１，４−シクロヘキシレンジイソシアネート、キシリレンジイソシアネート、テトラメチルキシリレンジイソシアネート、水素添加キシリレンジイソシアネート、リジンジイソシアネート、イソホロンジイソシアネート、４，４′−ジシクロヘキシルメタンジイソシアネートなどがあげられる。これら有機ポリイソシアネートは単独で使用してもよく、２種以上を併用してもよい。
【００２４】
本発明で用いるポリヒドロキシ化合物（Ｂ）としては、、エチレングリコール、プロピレングリコール、１，３−プロパンジオール、１，４−ブタンジオール、１，５−ペンタンジオール、３−メチル−１，５−ペンタンジオール、１，６−ヘキサンジオール、ネオペンチルグリコールジオール、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、ポリエチレングリコール、ジプロピレングリコール、トリプロピレングリコール、ビスヒドロキシエトキシベンゼン、１，４−シクロヘキサンジメタノール、ビスフェノールＡ、ビスフェノールＳ、水素添加ビスフェノールＡ、ハイドロキノン、これらジオールのアルキレンオキシド付加体などのジオール類；ソルビトール、１，２，３，６−ヘキサンテトラオール、１，４−ソルビタン、１，２，４−ブタントリオール、１，２，５−ペンタントリール、グリセリン、トリメチロールエタン、トリメチロールプロパン、ペンタエリスリトールなどの３官能以上のポリオール類；ポリエステルジオールなどのポリエステルポリオール、ポリエーテルジオールなどのポリエーテルポリオール、ポリカーボネートジオールなどのポリカーボネートポリオールなどがあげられる。これらポリヒドロキシ化合物は単独で使用してもよく、２種以上を併用してもよい。
【００２５】
前記ポリエステルポリオールとしては、たとえば、エチレングリコール、プロピレングリコール、１，３−プロパンジオール、１，４−ブタンジオール、１，５−ペンタンジオール、３−メチル−１，５−ペンタンジオール、１，６−ヘキサンジオール、ネオペンチルグリコールジオール、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、ポリエチレングリコール、ジプロピレングリコール、トリプロピレングリコール、ビスヒドロキシエトキシベンゼン、１，４−シクロヘキサンジメタノール、ビスフェノールＡ、ビスフェノールＳ、水素添加ビスフェノールＡ、ハイドロキノン、これらジオールのアルキレンオキシド付加体などのジオール成分の１種または２種以上と、マロン酸、コハク酸、グルタル酸、アジピン酸、ピメリン酸、スベリン酸、アゼライン酸、セバシン酸、ヘンデカンジカルボン酸、デカンジカルボン酸、ドデカンジカルボン酸、無水マレイン酸、フマル酸、１，３−シクロペンタンジカルボン酸、テレフタル酸、イソフタル酸、フタル酸、１，４−ナフタレンジカルボン酸、２，５−ナフタレンジカルボン酸、２，６−ナフタレンジカルボン酸、ナフタル酸、ビフェニルジカルボン酸、１，２−ビスフェノキシエタン−ｐ，ｐ′−ジカルボン酸、１，４−シクロヘキサンジカルボン酸、これらジカルボン酸の無水物ないしエステル形成性誘導体などの酸成分の１種または２種以上とから、脱水縮合反応によって得られるポリエステル類をはじめとして、さらにはε−カプロラクトンなどの環状エステル化合物の開環重合反応によって得られるポリエステル類、またはそれらの共重合ポリエステル類などがあげられる。
【００２６】
前記ポリエーテルポリオールとしては、たとえば、エチレングリコール、ジエチレングリコール、トリエチレングリコール、プロピレングリコール、トリメチレングリコール、１，３−ブタンジオール、１，４−ブタンジオール、１，５−ペンタンジオール、１，６−ヘキサンジオール、ネオペンチルグリコール、グリセリン、トリメチロールエタン、トリメチロールプロパン、ソルビトール、蔗糖、ビスフェノールＡ、ビスフェノールＳ、水素添加ビスフェノールＡ、アコニット酸、トリメリット酸、ヘミメリット酸、燐酸、エチレンジアミン、ジエチレントリアミン、トリイソプロパノールアミン、ピロガロール、ジヒドロキシ安息香酸、ヒドロキシフタール酸、１，２，３−プロパントリチオールなどの活性水素を少なくとも２個有する化合物またはエチレンジアミン、プロピレンジアミン等の１級アミノ基を少なくとも２個有する化合物を開始剤として、エチレンオキサイド、プロピレンオキサイド、ブチレンオキサイド、スチレンオキサイド、エピクロロヒドリン、テトラヒドロフラン、シクロヘキシレンなどのモノマーの１種または２種以上を用いて、常法により付加重合したものなどがあげられる。
【００２７】
前記ポリカーボネートポリオールとしては、たとえば、１，４−ブタンジオール、１，６−ヘキサンジオール、ジエチレングリコールなどのジオール類とジフェニルカーボネートおよびホスゲンとの反応によって得られる化合物などがあげられる。
【００２８】
本発明に使用するポリヒドロキシ化合物（Ｃ）の酸で中和または四級化剤で四級化する前の三級アミノ基を有するポリヒドロキシ化合物（Ｃｐ）としては、たとえば、下記一般式（Ｉ）：
【００２９】
【化１】

【００３０】
（式中、Ｒは炭素数１〜４のアルキル基またはヒドロキシアルキル基を表し、Ｒ¹およびＲ²は同一であっても相異なっていてもよく、それぞれ炭素数１〜４のアルキレン基を表す）で示される化合物があげられる。一般式（Ｉ）で示される化合物には、三級アミノ基を有するジオール化合物、三級アミノ基を有するトリオール化合物が含まれる。このような化合物のうち、ジオール化合物（Ｒがアルキル基である化合物）としては、Ｎ−メチル−Ｎ，Ｎ−ジエタノールアミン、Ｎ−エチル−Ｎ，Ｎ−ジエタノールアミン、Ｎ−イソブチル−Ｎ，Ｎ−ジエタノールアミンなどがあげられ、トリオール化合物（Ｒがヒドロキシアルキル基である化合物）としてはトリエタノールアミンなどがあげられる。
【００３１】
本発明においては、ＮＣＯ基と反応性のある活性水素原子を少なくとも２個有するポリヒドロキシ化合物（Ｂ）および分子中に酸で中和するかまたは四級化剤で四級化した三級アミノ基を有し、かつ、ＮＣＯ基と反応性のある活性水素原子を少なくとも２個有するポリヒドロキシ化合物（Ｃ）〔または分子中に三級アミノ基を有し、かつ、ＮＣＯ基と反応性のある活性水素原子を少なくとも２個有するポリヒドロキシ化合物（Ｃｐ）〕の平均活性水素濃度が１００〜８００（ｍｇＫＯＨ／ｇ）であるのが好ましい。平均活性水素濃度が１００未満の場合は、耐擦過性、耐熱性が劣る傾向にあり、一方８００を超える場合は紙加工特性が低下する傾向にある。
【００３２】
ここで、ポリヒドロキシ化合物（Ｂ）およびポリヒドロキシ化合物（Ｃ）の平均活性水素濃度は、つぎのようにして求められる値である。ＮＣＯ基と反応性のある活性水素原子を少なくとも２個有するポリヒドロキシ化合物（Ｂ）が、Ｂ１、Ｂ２……Ｂｋ（ここで、ｋは１以上の整数）の成分からなり、成分Ｂ１、Ｂ２……Ｂｋについて、活性水素濃度（ｍｇＫＯＨ／ｇ）がそれぞれＨ_B1、Ｈ_B2……Ｈ_BKであり、使用量（ｇ）がそれぞれＷ_B1、Ｗ_B2……Ｗ_Bkであるとする。また、分子中に酸で中和するかまたは四級化剤で四級化した三級アミノ基を有し、かつ、ＮＣＯ基と反応性のある活性水素原子を少なくとも２個有するポリヒドロキシ化合物（Ｃ）が、Ｃ１、Ｃ２……Ｃｍ（ここで、ｍは１以上の整数）の成分からなり、成分Ｃ１、Ｃ２……Ｃｍついて、活性水素濃度（ｍｇＫＯＨ／ｇ）がそれぞれＨ_C1、Ｈ_C2、Ｈ_Cmであり、使用量（ｇ）がそれぞれＷ_C1、Ｗ_C2……Ｗ_Cmであるとする。このような成分Ｂ１、Ｂ２……Ｂｋ、成分Ｃ１、Ｃ２……Ｃｍの混合物についての平均活性水素濃度は、次式：
【００３３】
【数２】

【００３４】
によって求められる。
【００３５】
ポリヒドロキシ化合物（Ｂ）とポリヒドロキシ化合物（Ｃｐ）の平均活性水素濃度も、前記と同様にして求められる。
【００３６】
本発明のカチオン性水性ポリウレタン樹脂は、
［Ｉ］（１）有機ポリイソシアネート（Ａ）、ポリヒドロキシ化合物（Ｂ）、分子中に三級アミノ基を有し、かつ、ＮＣＯ基と反応性のある活性水素原子を少なくとも２個有するポリヒドロキシ化合物（Ｃｐ）とを反応させてウレタンプレポリマーを得、ついで該ウレタンプレポリマーの三級アミノ基を酸で中和するかまたは四級化剤で四級化してカチオン性ウレタンプレポリマーを得るか、あるいは
（２）有機ポリイソシアネート（Ａ）、ポリヒドロキシ化合物（Ｂ）、分子中に酸で中和するかまたは四級化剤で四級化した三級アミノ基を有し、かつ、ＮＣＯ基と反応性のある活性水素原子を少なくとも２個有するポリヒドロキシ化合物（Ｃ）とを反応させてカチオン性ウレタンプレポリマーを得るカチオン性ウレタンプレポリマーの製造工程と、
［ＩＩ］該カチオン性ウレタンプレポリマーをポリアミン化合物で鎖伸長してカチオン性水系ポリウレタン樹脂を得る工程
からなる製造方法によって製造することができる。
【００３７】
前記三級アミノ基を中和するために用いられる酸としては、蟻酸、酢酸、プロピオン酸、酪酸、乳酸、リンゴ酸、クエン酸などの有機酸および塩酸、リン酸、亜リン酸、硝酸などの無機酸があげられる。また、四級化剤としては、エチレンオキシド、プロピレンオキシド、ブチレンオキサイド、スチレンオキサイド、エピクロロヒドリンなどのエポキシ化合物、ジメチル硫酸、ジエチル硫酸などのジアルキル硫酸類、パラトルエンスルホン酸メチルなどのスルホン酸アルキル類、メチルクロライド、エチルクロライド、ベンジルクロライド、メチルブロマイド、エチルブロマイドなどのハロゲン化アルキル類などがあげられる。
【００３８】
有機ポリイソシアネート（Ａ）が芳香族イソシアネートなどの反応性の高いイソシアネートの場合は、工程［Ｉ］において、三級アミノ基を有するポリヒドロキシ化合物（Ｃｐ）を用いてウレタンプレポリマーを製造したのち、三級アミノ基をカチオン化する方法（１）を採ると、ゲル化などの惧れがあるので、カチオン化した三級アミノ基を有するポリヒドロキシ化合物（Ｃ）を用いてウレタンプレポリマーを製造する方法（２）が好ましい。
【００３９】
工程［Ｉ］においては、有機ポリイソシアネート（Ａ）と、ポリヒドロキシ化合物（Ｂ）および分子中に酸で中和するかまたは四級化剤で四級化した三級アミノ基を有し、かつ、ＮＣＯ基と反応性のある活性水素原子を少なくとも２個有するポリヒドロキシ化合物（Ｃ）〔またはポリヒドロキシ化合物（Ｂ）および分子中に三級アミノ基を有し、かつ、ＮＣＯ基と反応性のある活性水素原子を少なくとも２個有するポリヒドロキシ化合物（Ｃｐ）〕とを、好ましくは、（Ａ）のイソシアネート基の当量と（Ｂ）および（Ｃ）〔または（Ｃｐ）〕の活性水素原子の当量の合計の比が１．０／１．０〜１．０／０．５となるように反応させて、末端イソシアネート基のウレタンプレポリマーを製造する。
【００４０】
分岐密度が０．０８〜０．２５のカチオン性ウレタンプレポリマーを製造するには、ポリヒドロキシ化合物（Ｂ）として、ジオールと官能基数が３以上のポリオールの混合物を使用し、さらに、ポリヒドロキシ化合物（Ｃ）〔またはポリヒドロキシ化合物（Ｃｐ）〕として官能基数が２の化合物を使用し、有機ポリイソシアネートとして、ジイソシアネートを使用すると、分岐密度の調節が容易である。
【００４１】
工程［Ｉ］におけるイソシアネート重付加反応は、組成によって無溶剤下に行うこともできるが、反応系の反応抑制やベース粘度コントロールなどの目的でイソシアネート重付加反応系に直接関与しない親水性有機溶剤を反応溶媒として用いて実施することが一般的である。かかる親水性有機溶剤としては、アセトン、メチルエチルケトン、メチルイソブチルケトン、ジイソブチルケトンなどのケトン類、蟻酸メチル、蟻酸エチル、蟻酸プロピル、蟻酸ブチル、酢酸メチル、酢酸エチル、酢酸プロピル、酢酸ブチル、プロピオン酸メチル、プロピオン酸エチル、プロピオン酸ブチルなどの有機酸エステル、Ｎ，Ｎ−ジメチルホルムアミド、Ｎ−メチルピロリドンのなどのアミン類などがあげられる。反応に使用した親水性有機溶剤は最終的には取り除かれるのが好ましい。
【００４２】
工程［ＩＩ］では、工程［Ｉ］で得られたカチオン性ウレタンプレポリマーをポリアミン化合物で鎖伸長する。たとえば、工程［Ｉ］で得られたカチオン性ウレタンプレポリマーの溶液に水を加えて乳化した後、ポリアミン化合物を加えて鎖伸長反応を行わせ、ついで溶剤を除去すると、カチオン性水系ポリウレタン樹脂のエマルジョンが得られる。ポリアミン化合物で鎖伸長することにより、前記のような高分子量のポリウレタン樹脂を容易に得ることができる。
【００４３】
鎖伸長剤として用いるポリアミン化合物としては、たとえばエチレンジアミン、トリメチレンジアミン、プロピレンジアミン、テトラメチレンジアミン、ペンタメチレンジアミン、ヘキサメチレンジアミンなどの一級アミノ基を２個有する脂肪族ジアミン化合物；トリレンジアミン、キシレンジアミン、ジアミノジフェニルメタンなどの一級アミノ基を２個有する芳香族ジアミン化合物；ジアミノシクロヘキシルメタンなどの一級アミノ基を２個有する脂環式ジアミン化合物；ピペラジン、２−メチルピペラジンなどのピペラジン誘導体;イソホロンジアミン;ジエチレントリアミン、ジプロピレントリアミン、トリエチレンテトラミン、テトラエチレンペンタミンなどの一級アミノ基を２個有し、２級アミノ基を１個以上有する脂肪族ポリアミン化合物；ヒドラジン、アジピン酸ヒドラジドなどのジヒドラジン誘導体；メラミンなどの一級アミノ基を３個以上有するポリアミン化合物などがあげられる。
【００４４】
カチオン性水系ポリウレタン樹脂エマルジョンの平均粒子径は、紙に対する浸透性の関係から、０．００１〜０．１μｍの範囲が好ましい。
【００４５】
本発明のインクジェット記録紙用塗工剤は前記カチオン性水系ポリウレタン樹脂のエマルジョンを含有するものであるが、インクジェット記録紙用塗工剤に一般に使用されている、たとえば水溶性高分子、無機充填剤などの各種添加剤を配合してもよい。水溶性高分子としては、たとえば、酸化デンプン、ポリビニルアルコール、ゼラチン、ポリビニルピロリドン、ポリアクリルアミド、ポリアクリル酸ソーダ、カゼイン、カルボキシメチルセルロースなどがあげられる。無機充填剤としては、たとえば、軽質炭酸カルシウム、重質炭酸カルシウム、カオリン、タルク、硫酸カルシウム、硫酸バリウム、酸化チタン、酸化亜鉛、硫酸亜鉛、炭酸亜鉛、サチンホワイト、珪酸アルミニウム、ケイソウ土、珪酸カルシウム、無定形シリカ、水酸化アルミニウム、アルミナ、リトポンなどがあげられる。印字速度、発色性などの点からは、無定形シリカが好ましい。
【００４６】
本発明のインクジェット記録紙用塗工剤における前記カチオン性水系ポリウレタン樹脂の含有量は、その優れた性能を充分に発揮させる点から、５重量％以上であるのが好ましい。
【００４７】
本発明のインクジェット記録紙用塗工剤を紙基材に塗布することによって、インクジェット記録紙が得られる。紙基材としては、普通紙、塗工紙などが使用できる。塗工剤の乾燥後の塗布厚さは３〜３０μｍ程度が適当である。
【００４８】
【実施例】
つぎに本発明を実施例をあげて説明する。
【００４９】
下記の実施例で得られたカチオン性ポリウレタン樹脂の重量平均分子量は、カチオン性ポリウレタン樹脂の相対分子量分布をＧＰＣ（ゲル浸透クロマトグラフィー）により求め、ポリエチレングリコール換算重量平均分子量として求めた。ＧＰＣの測定条件はつぎのとおりである。
【００５０】
測定機種：東ソー（株）製ＳＣ−８０１０システム
カラム：Ｓｈｏｄｅｘ Ｏｈｐａｋ ＳＢ−Ｇ＋Ｏｈｐａｋ ＳＢ−８０６ＭＨＱ×２本
溶解液：ＤＭＦ／０．０６Ｍ ＬｉＢｒ／０．０４Ｍ Ｈ₃ＰＯ₃
温度：カラム恒温槽４０℃
流速：１．０ｍｌ／分
濃度：０．１ｗｔ／Ｖｏｌ％
注入量：１００μｌ
溶解性：完全溶解
前処理：０．４５μｍフィルター
検出器：示差屈折計
【００５１】
用いたポリヒドロキシ化合物の活性水素濃度は次のようにして求める。
【００５２】
試料を推定活性水素濃度に応じてサンプリングし重量を測定した後、５ｍｌのアセチル化試薬（使用直前に無水酢酸１容量部とピリジン２容量部を混合して調製する）を加え１０〜１５分間加熱してアセチル化を行う。その後水２ｍｌを加え冷却し、約２０分間放置して過剰の無水酢酸を加水分解する。これに中性エタノール６０ｍｌを加え、フエノールフタレイン指示薬０．２ｍｌを加えて１ｍｏｌ／ｌ水酸化カリウム標準液で滴定し、つぎの式により求める。
【００５３】
活性水素濃度（ｍｇＫＯＨ／ｇ）
＝［（Ｂ−Ｓ）×ｆ×５６．１１］／試料の質量（ｇ）＋ＡＶ
Ｂ：空試験に要した１ｍｏｌ／ｌ水酸化カリウム標準液のｍｌ
Ｓ：実試験に要した１ｍｏｌ／ｌ水酸化カリウム標準液のｍｌ
ｆ：１ｍｏｌ／ｌ水酸化カリウム標準液の力価
ＡＶ：同一試料の酸価
【００５４】
実施例１
ポリブチレンアジペートジオール（重量平均分子量２０００、商品名ニッポラン４０１０、日本ポリウレタン工業（株）製）３００重量部、トリメチロールプロパン（分子量１３４）９．０重量部、Ｎ−メチル−Ｎ，Ｎ−ジエタノールアミン４９重量部、イソホロンジイソシアネート１８０重量部、メチルエチルケトン３７７重量部を反応容器にとり、７０〜７５℃に保ちながら９０分間反応させ、ついでジメチル硫酸３８．１重量部を添加し、５０〜６０℃で２０分間反応させて、ＮＣＯ含有率が２．２重量％であるカチオン性ウレタンポリマーの溶液を得た。この溶液に撹拌下に水１３７０重量部を一括添加して乳化後、ただちにエチレンジアミン８．４重量部を水４０重量部に溶解した溶液を添加し、３０℃で６０分間反応させて鎖伸長を行わせ、次いでメチルエチルケトンを留去させることにより、重量平均分子量７５万のカチオン性ポリウレタン樹脂のエマルジョン（固形分濃度３０重量％、エマルジョン平均粒子径０．０３μｍ）を得た。なお、前記ポリブチレンアジペートジオールとトリメチロールプロパンとＮ−メチル−Ｎ，Ｎ−ジエタノールアミンの平均活性水素濃度は２０７（ｍｇＫＯＨ／ｇ）であった。また前記カチオン性ウレタンプレポリマーの分岐密度は０．１２であった。
【００５５】
実施例２
１，６−ヘキサンジオールおよびエチレングリコールとイソフタル酸およびアジピン酸から得られたポリエステルジオール（重量平均分子量１０００、商品名ＴＡ−２２−４１９Ａ、日立化成ポリマー（株）製）２４０重量部、トリメチロールプロパン（分子量１３４）８．０重量部、Ｎ−メチル−Ｎ，Ｎ−ジエタノールアミン４１重量部、イソホロンジイソシアネート１８０重量部、メチルエチルケトン３１０重量部を反応容器にとり、７０〜７５℃に保ちながら６０分間反応させ、ついでジメチル硫酸３２．５重量部を添加し、５０〜６０℃で２０分間反応させて、ＮＣＯ含有率が２．３重量％であるカチオン性ウレタンポリマーの溶液を得た。この溶液に撹拌下に水１２９０重量部を一括添加して乳化後、ただちにエチレンジアミン７．７重量部を水４０重量部に溶解した溶液を添加し、３０℃で６０分間反応させて鎖伸長を行わせ、次いでメチルエチルケトンを留去させることにより、重量平均分子量４５万のカチオン性ポリウレタン樹脂のエマルジョン（固形分濃度２８重量％、エマルジョン平均粒子径０．０２μｍ）を得た。なお、前記ポリエステルジオールとトリメチロールプロパンとＮ−メチル−Ｎ，Ｎ−ジエタノールアミンの平均活性水素濃度は２６１（ｍｇＫＯＨ／ｇ）であった。また前記カチオン性ウレタンプレポリマーの分岐密度は０．１３であった。
【００５６】
実施例３
ビスフェノールＡのエチレンオキサイド２モル付加物（重量平均分子量３３０、商品名ニューポールＢＰＥ−２０ＮＫ、三洋化成工業（株）製）１５０重量部、トリメチロールプロパン（分子量１３４）１１重量部、Ｎ−メチル−Ｎ，Ｎ−ジエタノールアミン４４重量部、４，４’−ジシクロヘキシルメタンジイソシアネート３００重量部、メチルエチルケトン４５０重量部を反応容器にとり、７０〜７５℃に保ちながら１２０分間反応させ、ついでジメチル硫酸３２．７重量部を添加し、５０〜６０℃で２０分間反応させて、ＮＣＯ含有率が３．１重量％であるカチオン性ウレタンポリマーの溶液を得た。この溶液に撹拌下に水１５７７重量部を一括添加して乳化後、ただちにエチレンジアミン１１．２重量部を水５０重量部に溶解した溶液を添加し、３０℃で６０分間反応させて鎖伸長を行わせ、次いでメチルエチルケトンを留去させることにより、重量平均分子量９０万のカチオン性ポリウレタン樹脂のエマルジョン（固形分濃度２７重量％、エマルジョン平均粒子径０．０４μｍ）を得た。なお、前記ビスフェノールＡのエチレンオキサイド２モル付加物とトリメチロールプロパンとＮ−メチル−Ｎ，Ｎ−ジエタノールアミンの平均活性水素濃度は５２０（ｍｇＫＯＨ／ｇ）であった。また前記カチオン性ウレタンプレポリマーの分岐密度は０．１６であった。
【００５７】
実施例４
Ｎ−メチル−Ｎ，Ｎ−ジエタノールアミン３９．６重量部とメチルエチルケトン１７５重量部を反応容器にとり、これにジメチル硫酸４１．９重量部をメチルエチルケトン７０重量部に溶解した溶液を徐々に滴下し、４０〜５０℃で１０分間四級化反応を行わせた。この反応容器に、ビスフェノールＡのエチレンオキサイド２モル付加物（重量平均分子量３３０、商品名ニューポールＢＰＥ−２０ＮＫ、三洋化成工業（株）製）１２３．８重量部、トリメチロールプロパン（分子量１３４）９．９重量部、トリレンジイソシアネート１７５．８重量部、メチルエチルケトン３５０重量部を加え、７０〜７５℃に保ちながら１８０分間反応させ、ＮＣＯ含有率が４．４重量％であるカチオン性ウレタンポリマーの溶液を得た。この溶液に撹拌下に水９１２重量部を一括添加して乳化後、ただちにアジピン酸ヒドラジド３１．８重量部を水１２０重量部に溶解した溶液を添加し、３０℃で３０分間反応させて鎖伸長を行わせ、次いでメチルエチルケトンを留去させることにより、重量平均分子量９５万のカチオン性ポリウレタン樹脂のエマルジョン（固形分濃度２７重量％、エマルジョン平均粒子径０．０４μｍ）を得た。なお、前記ビスフェノールＡのエチレンオキサイド２モル付加物とトリメチロールプロパンと四級化Ｎ−メチル−Ｎ，Ｎ−ジエタノールアミンの平均活性水素濃度は５３１（ｍｇＫＯＨ／ｇ）であった。また前記カチオン性ウレタンプレポリマーの分岐密度は０．２１であった。
【００５８】
実施例５
ポリテトラメチレングリコール（重量平均分子量２５０、商品名ＴＥＲＡＴＨＡＮＥ２５０、デュポン社製）３４重量部、１，４−シクロヘキサンジメタノール（分子量１４４．２）４５．８重量部、トリメチロールプロパン（分子量１３４）８．９重量部、Ｎ−メチル−Ｎ，Ｎ−ジエタノールアミン３６重量部、４，４’−ジシクロヘキシルメタンジイソシアネート２６８重量部、メチルエチルケトン３００重量部を反応容器にとり、７０〜７５℃に保ちながら１２０分間反応させ、ついでジメチル硫酸２９．７重量部を添加し、５０〜６０℃で２０分間反応させて、ＮＣＯ含有率が３．６重量％であるカチオン性ウレタンポリマーの溶液を得た。この溶液に撹拌下に水１４２０重量部を一括添加して乳化後、ただちにエチレンジアミン９．８重量部を水５０重量部に溶解した溶液を添加し、３０℃で６０分間反応させて鎖伸長を行わせ、次いでメチルエチルケトンを留去させることにより、重量平均分子量７５万のカチオン性ポリウレタン樹脂のエマルジョン（固形分濃度２６重量％、エマルジョン平均粒子径０．０１μｍ）を得た。なお、前記ポリテトラメチレングリコールと１，４−シクロヘキサンジメタノールとトリメチロールプロパンとＮ−メチル−Ｎ，Ｎ−ジエタノールアミンの平均活性水素濃度は７７０（ＫＯＨｍｇ／ｇ）であった。また前記カチオン性ウレタンプレポリマーの分岐密度は０．１７であった。
【００５９】
実施例６
ポリカーボネートジオール（重量平均分子量１０００、商品名ニッポラン９８１、日本ポリウレタン工業（株）製）２５０重量部、ポリエチレングリコール（重量平均分子量６００、商品名ＰＥＧ６００Ｓ、第一工業製薬（株）製）１０重量部、トリメチロールプロパン（分子量１３４）７．０重量部、Ｎ−メチル−Ｎ，Ｎ−ジエタノールアミン３１重量部、４，４’−ジシクロヘキシルメタンジイソシアネート２００重量部、メチルエチルケトン４００重量部を反応容器にとり、７０〜７５℃に保ちながら１２０分間反応させ、ついでジメチル硫酸３２重量部を添加し、５０〜６０℃で２０分間反応させて、ＮＣＯ含有率が２．５重量％であるカチオン性ウレタンポリマーの溶液を得た。この溶液に撹拌下に水１３２０重量部を一括添加して乳化後、ただちにエチレンジアミン８．９重量部を水５０重量部に溶解した溶液を添加し、３０℃で６０分間反応させて鎖伸長を行わせ、次いでメチルエチルケトンを留去させることにより、重量平均分子量７３万のカチオン性ポリウレタン樹脂のエマルジョン（固形分濃度２５重量％、エマルジョン平均粒子径０．０３μｍ）を得た。なお、前記ポリカーボネートジオールとポリエチレングリコールとトリメチロールプロパンとＮ−メチル−Ｎ，Ｎ−ジエタノールアミンの平均活性水素濃度は２２８（ｍｇＫＯＨ／ｇ）であった。また前記カチオン性ウレタンプレポリマーの分岐密度は０．１０であった。
【００６０】
比較例１
ポリテトラメチレングリコール（重量平均分子量２０００、商品名ＰＴＭＧ１０００、三菱化学（株）製）２３８重量部、Ｎ−メチル−Ｎ，Ｎ−ジエタノールアミン３８．１重量部、イソホロンジイソシアネート１３７重量部、メチルエチルケトン２１０重量部を反応容器にとり、７０〜７５℃に保ちながら１５０分間反応させ、ついでジメチル硫酸３２．３重量部を添加し、５０〜６０℃で２０分間反応させて、ＮＣＯ含有率が２．０重量％であるカチオン性ウレタンポリマーの溶液を得た。この溶液に撹拌下に水１１５５重量部を一括添加して乳化後、ただちにエチレンジアミン６．０重量部を水４０重量部に溶解した溶液を添加し、３０℃で６０分間反応させて鎖伸長を行わせ、次いでメチルエチルケトンを留去させることにより、重量平均分子量６２万のカチオン性ポリウレタン樹脂のエマルジョン（固形分濃度３０重量％、エマルジョン平均粒子径０．０２μｍ）を得た。なお、前記ポリテトラメチレングリコールとＮ−メチル−Ｎ，Ｎ−ジエタノールアミンの平均活性水素濃度は２２７（ｍｇＫＯＨ／ｇ）であった。また前記カチオン性ウレタンプレポリマーの分岐密度はゼロであった。
【００６１】
比較例２
ポリエステルジオール（重量平均分子量４０００、商品名ＨＯＫＯＫＵＯＬ ＨＴ−４００、豊国製油（株）製）４００重量部、トリメチロールプロパン（分子量１３４）２４重量部、Ｎ−メチル−Ｎ，Ｎ−ジエタノールアミン１８重量部、イソホロンジイソシアネート１５０重量部、メチルエチルケトン５９２重量部を反応容器にとり、７０〜７５℃に保ちながら１５０分間反応させ、ついでジメチル硫酸１８．０重量部を添加し、５０〜６０℃で２０分間反応させて、ＮＣＯ含有率が３．２重量％であるカチオン性ウレタンポリマーの溶液を得た。この溶液に撹拌下に水１５２０重量部を一括添加して乳化後、ただちにエチレンジアミン６．０重量部を水４０重量部に溶解した溶液を添加し、３０℃で６０分間反応させて鎖伸長を行わせ、次いでメチルエチルケトンを留去させることにより、重量平均分子量７６万のカチオン性ポリウレタン樹脂のエマルジョン（固形分濃度３０重量％、エマルジョン平均粒子径０．１５μｍ）を得た。なお、前記ポリエステルジオールとトリメチロールプロパンとＮ−メチル−Ｎ，Ｎ−ジエタノールアミンの平均活性水素濃度は１３２（ｍｇＫＯＨ／ｇ）であった。また前記カチオン性ウレタンプレポリマーの分岐密度は０．２９であった。
【００６２】
実施例７〜１２および比較例３、４
実施例１〜６および比較例１、２で得られた各カチオン性ポリウレタン樹脂エマルジョン５０重量部に無定形シリカ５０重量部、２０重量％ポリビニルアルコール水溶液２００重量部を配合してインクジェット記録紙用塗工液を調製し、これを上質紙にバーコーターにより乾燥後厚さが２５μｍになるように塗布し、１００℃で３分間乾燥して、インクジェット記録紙を得た。
【００６３】
得られたインクジェット記録紙について、下記の項目について評価した。結果を表１に示す。
【００６４】
（１）インク定着性
前記インクジェット記録紙の塗工面にインクジェットプリンター（セイコーエプソン（株）製ＭＡＣＨＪＥＴ ＭＪ−８３０Ｃ）で印刷し、記録画像に指触したときにインクが付着しなくなるまでの時間により評価した。
評価基準
◎：２０秒未満
○：２０〜６０秒
×：６０秒を超える
【００６５】
（２）耐水性
前記（１）と同様に印刷し、印字部と非印字部の境界にスポイトで水を１滴滴下して印字の滲みを目視で観察して評価した。
評価基準
◎：まったく滲まない
○：僅かに滲む（印字の識別可能）
×：滲む（印字の識別不可能）
【００６６】
（３）紙加工性
インクジェット記録紙用塗工液を塗布し乾燥した後の塗工面のひび割れを目視で観察して評価した。
評価基準
◎：ひび割れなし
○：２ｍｍ以内のひび割れあり
×：２ｍｍを超えるひび割れあり
【００６７】
（４）耐擦過性
印字していないＡ４サイズのインクジェット記録紙について、インクジェットプリンター（セイコーエプソン（株）製ＭＡＣＨＪＥＴ ＭＪ−８３０Ｃ）を用いて紙送りを繰り返すことにより評価した。
評価基準
◎：非常に良好（５０回紙送りしても塗工面に傷つきなし）
○：良好（３０回紙送りしても塗工面に傷つきなし）
△：やや良好（１０〜３０回の紙送りで塗工面に傷発生）
×：不良（１０回未満の紙送りで塗工面に傷発生）
【００６８】
（５）寸法安定性
前記インクジェット記録紙の塗工面にインクジェットプリンター（セイコーエプソン（株）製ＭＡＣＨＪＥＴ ＭＪ−８３０Ｃ）でベタ印刷し、印刷前の用紙寸法と印刷後の用紙寸法を比較することにより評価した（印刷前の用紙面積に対する印刷後の用紙面積の増加率で比較した）。
評価基準
◎：非常に優れる（寸法変化なし）
○：良好（寸法変化１％以内）
×：不良（寸法変化が１％を超える）
【００６９】
（６）耐熱性
前記インクジェット記録紙の塗工面にインクジェットプリンター（セイコーエプソン（株）製ＭＡＣＨＪＥＴ ＭＪ−８３０Ｃ）でカラー印刷した後、６０℃で３日間保存して各色の変化を目視観察して判定した。このテストは、高温で保存した場合にインクジェット記録紙用塗工剤がインクの色目に影響する度合いを調べるものである。
評価基準
◎：非常に優れる（まったく変化なし）
○：良好（僅かに変化が認められる）
×：不良（変化あり、画像としての価値がないレベル）
【００７０】
（７）耐溶剤性
前記インクジェット記録紙の塗工面にインクジェットプリンター（セイコーエプソン（株）製ＭＡＣＨＪＥＴ ＭＪ−８３０Ｃ）で印刷した後、メタノールをつけた綿棒で印字面を軽く擦ることにより評価した。
評価基準
◎：非常に優れる（５０回擦っても、くもり、脱落なし）
○：良好（３０回擦っても、くもり、脱落なし）
△：やや劣る（１０〜３０回の擦りで、くもり、脱落発生）
×：不良（１０回未満の擦りで、くもり、脱落発生）
【００７１】
【表１】

【００７２】
【発明の効果】
本発明の特定のカチオン性水系ポリウレタン樹脂からなるインクジェット記録紙用塗工剤は、インク定着性、耐水性はもとより、耐擦過性、印刷時の寸法安定性、耐熱性、耐溶剤性、無機充填剤に対するバインダー能力などがともに優れている。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coating agent for inkjet recording paper and an inkjet recording paper coated with the same.
[0002]
[Prior art]
Inkjet recording has the characteristics that the recording device is simple, plain paper or coated paper can be used, colorization is easy, and beautiful full-color images and text figures can be recorded easily. It is spreading rapidly.
[0003]
Ink-jet recording generally uses a water-based ink containing a dye as a colorant. However, this water-based ink uses water as a medium, and thus has a problem that ink fixability (ink drying property) is inferior, and a dye is used. Therefore, there are problems such as poor water resistance of recorded images. In order to solve these problems, various chemicals are applied to a paper substrate. For example, it has been proposed to apply a cationic resin such as dicyandiamide condensate, polyamine, or polyethyleneimine. When water-based ink is recorded on an ink jet recording paper coated with such a cationic resin, it is expected that the water resistance is improved by combining the dye in the ink with the cationic resin of the coating layer. However, neither ink fixing property nor water resistance is sufficient.
[0004]
Japanese Patent No. 2884532 proposes using a cationic polyurethane resin as a coating agent for ink jet recording paper, but the specifically disclosed cationic polyurethane resin contains diol, tertiary A diol having an amino group and an aliphatic diisocyanate are reacted to obtain a urethane prepolymer, and then a tertiary amino group in the urethane prepolymer is neutralized with an acid to form a cationic urethane prepolymer, and then the cation A cationic polyurethane resin having a weight average molecular weight of 2,000 to 50,000 is obtained by chain-extending a functional urethane prepolymer with water.
[0005]
In this cationic polyurethane resin, the ink fixing property and water resistance are considerably improved, but scratches are easily caused by rubbing the coated surface (poor scratch resistance), and the recording paper extends when printed with aqueous ink (when printing) Binders for inorganic fillers, images are discolored when the printed matter is stored at high temperature (heat resistance is poor), and images are removed when the printed surface is rubbed with an organic solvent (solvent resistance is poor). Suppresses side reactions in the urethanization reaction when there is a problem such as inferior ability and the use of highly reactive aromatic isocyanate or a large amount of tertiary amino group-containing diol is used. However, it is difficult to control the reaction, and there is a concern that the emulsification may be poor due to abnormal thickening or gelation may occur in the urethane synthesis stage. Improvement of these points is desired.
[0006]
[Problems to be solved by the invention]
In view of the problems of the prior art, the present invention has excellent ink fixing properties, water resistance, scratch resistance, dimensional stability during printing, heat resistance, solvent resistance, binder ability for inorganic fillers, and the like. It is an object of the present invention to provide a coating agent for inkjet recording paper comprising a cationic polyurethane resin.
[0007]
Furthermore, the present invention relates to an inkjet recording paper comprising a cationic polyurethane resin that can be stably produced even when a highly reactive aromatic isocyanate is used or when the amount of tertiary amino group-containing diol is large. An object is to provide a coating agent.
[0008]
[Means for Solving the Problems]
The present invention provides the following coating agent for ink jet recording paper and ink jet recording paper coated therewith.
[0009]
(1) (A) a structural unit derived from an organic polyisocyanate, (B) a structural unit derived from a polyhydroxy compound having at least two active hydrogen atoms reactive with an NCO group, and (C) a molecule Derived from a polyhydroxy compound having a tertiary amino group neutralized with acid or quaternized with a quaternizing agent and having at least two active hydrogen atoms reactive with NCO groups An ink jet recording comprising an emulsion of a cationic water-based polyurethane resin comprising a constituent unit and having a chain extension of a cationic urethane prepolymer having a branch density of 0.08 to 0.25 per 1000 atomic weights by a polyamine compound Paper coating agent.
[0010]
(2) The coating agent for inkjet recording paper according to (1), wherein the average active hydrogen concentration of the polyhydroxy compound (B) and the polyhydroxy compound (C) is 100 to 800 (mg KOH / g).
[0011]
(3) The coating agent for inkjet recording paper according to (1) or (2), wherein the emulsion of the cationic aqueous polyurethane resin has an average particle size of 0.001 to 0.1 μm.
[0012]
(4) The cationic urethane prepolymer has at least an active hydrogen atom having an organic polyisocyanate (A), a polyhydroxy compound (B), a tertiary amino group in the molecule and reactive with an NCO group. It was obtained by reacting with two polyhydroxy compounds (Cp) to obtain a urethane prepolymer, and then neutralizing the tertiary amino group of the urethane prepolymer with an acid or quaternizing with a quaternizing agent. The coating agent for inkjet recording paper according to any one of (1) to (3), which is a product.
[0013]
(5) When the organic polyisocyanate (A) is an aromatic polyisocyanate, the cationic urethane prepolymer is neutralized with an acid in the organic polyisocyanate (A), the polyhydroxy compound (B), or the molecule It is obtained by reacting a polyhydroxy compound (C) having a tertiary amino group quaternized with a quaternizing agent and having at least two active hydrogen atoms reactive with an NCO group. The coating agent for inkjet recording paper according to any one of (1) to (3).
[0014]
(6) The coating agent for inkjet recording paper according to any one of (1) to (5), wherein the water-based polyurethane resin has a weight average molecular weight of 100,000 to 1,000,000.
[0015]
(7) An ink jet recording paper obtained by applying the coating agent according to any one of (1) to (6) onto a paper substrate.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The coating agent for inkjet recording paper of the present invention is derived from (A) a structural unit derived from an organic polyisocyanate and (B) a polyhydroxy compound having at least two active hydrogen atoms reactive with NCO groups. And (C) a tertiary amino group neutralized with an acid or quaternized with a quaternizing agent in the molecule, and at least 2 active hydrogen atoms reactive with the NCO group An emulsion of a cationic water-based polyurethane resin comprising a cationic urethane prepolymer having a branch density of 0.08 to 0.25 per 1000 atomic weights and chain-extended with a polyamine compound. It is characterized by containing.
[0017]
Here, the branch density per 1000 atomic weight of the cationic urethane prepolymer referred to in the present invention is a value determined as follows. That is, the organic polyisocyanate (A) is composed of components A1, A2... Aj (where j is an integer of 1 or more), and the molecular weights of components A1, A2... Aj are MW _A1 , MW _A2 . ... a MW _Aj, functionality is F _A1, F _A2 ...... F _Aj, respectively, the amount (g) is assumed to be W _A1, W _A2 ...... W _Aj, respectively. In addition, the polyhydroxy compound (B) having at least two active hydrogen atoms reactive with the NCO group is composed of components B1, B2... Bk (where k is an integer of 1 or more), and component B1, For B2, Bk, the molecular weights are MW _B1 , MW _B2, MW _BK , the number of functional groups is F _B1 , F _B2, F _Bk , and the usage (g) is W _B1 , W _B2 , respectively ... W _Bk . Further, a polyhydroxy compound having a tertiary amino group neutralized with an acid or quaternized with a quaternizing agent in the molecule and having at least two active hydrogen atoms reactive with an NCO group ( C) is composed of components C1, C2... Cm (where m is an integer of 1 or more), and the components C1, C2... Cm have molecular weights MW _C1 , MW _C2 , and MW _Cm , respectively. radix is F _C1, F _C2 ...... F _Cm respectively, the amount (g) is assumed to be W _C1, W _C2 ...... W _Cm, respectively. The branch density per 1000 atomic weight of the cationic urethane prepolymer obtained by reacting such components A1, A2... Aj, components B1, B2... Bk and components C1, C2. formula:
[0018]
[Expression 1]

[0019]
Sought by.
[0020]
In the present invention, a cationic aqueous polyurethane resin obtained by chain-extending a cationic urethane prepolymer having a branch density of 0.08 to 0.25 per 1000 atomic weight with a polyamine compound is used as a coating agent for inkjet recording paper. As a result, it was found that ink fixing properties (drying properties) and water resistance were excellent, as well as scratch resistance, dimensional stability during printing, heat resistance, solvent resistance, and binder ability for inorganic fillers. . That is, an ink jet recording paper coated with a cationic aqueous polyurethane resin obtained by chain-extending a cationic urethane prepolymer having a branch density of 0.08 to 0.25 per 1000 atomic weight with a polyamine compound is scratched even if the coated surface is rubbed. Difficult to scratch (excellent scratch resistance), recording paper does not stretch even when printed with water-based ink (excellent dimensional stability during printing), and color changes even when the printed matter is stored at high temperatures Even when an inorganic filler is used in combination, the coating surface is uniform and has good coatability even when the printed surface is rubbed with an organic solvent and the image does not fall off (excellent solvent resistance). The excellent effect that a work layer can be formed (the binder ability with respect to an inorganic filler is excellent) is exhibited.
[0021]
When the branch density is less than 0.08, the scratch resistance, dimensional stability during printing, and heat resistance are poor. When the branch density exceeds 0.25, the minimum film-forming temperature of the polyurethane resin becomes too high, which is not preferable for processing.
[0022]
In order to obtain excellent scratch resistance, printing stability, heat resistance, and solvent resistance, the cationic water-based polyurethane resin preferably has a weight average molecular weight of 100,000 to 1,000,000, more preferably 400,000 to 1 million. When the weight average molecular weight of the cationic water-based polyurethane resin is less than the above range, the scratch resistance, stability during printing, heat resistance, and solvent resistance tend to be inferior. On the other hand, when the weight average molecular weight exceeds the above range, the film forming temperature of the polyurethane resin tends to be high, and the processability tends to deteriorate.
[0023]
Examples of the organic polyisocyanate (A) used in the present invention include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 3,3'-dichloro-4,4'-biphenylene diisocyanate, 1,5- Naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diiso Anate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, hydrogenated xylylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, etc. can give. These organic polyisocyanates may be used alone or in combination of two or more.
[0024]
Examples of the polyhydroxy compound (B) used in the present invention include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 3-methyl-1,5-pentane. Diol, 1,6-hexanediol, neopentyl glycol diol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanedimethanol, bisphenol A , Bisphenol S, hydrogenated bisphenol A, hydroquinone, diols such as alkylene oxide adducts of these diols; sorbitol, 1,2,3,6-hexanetetraol Tri- or higher functional polyols such as 1,4-sorbitan, 1,2,4-butanetriol, 1,2,5-pentanthryl, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol; polyester such as polyester diol Examples thereof include polyether polyols such as polyols and polyether diols, and polycarbonate polyols such as polycarbonate diols. These polyhydroxy compounds may be used alone or in combination of two or more.
[0025]
Examples of the polyester polyol include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6- Hexanediol, neopentyl glycol diol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanedimethanol, bisphenol A, bisphenol S, hydrogenated One or more diol components such as bisphenol A, hydroquinone, alkylene oxide adducts of these diols, malonic acid, succinic acid, glutaric acid, Dipic acid, Pimelic acid, Suberic acid, Azelaic acid, Sebacic acid, Hendecanedicarboxylic acid, Decanedicarboxylic acid, Dodecanedicarboxylic acid, Maleic anhydride, Fumaric acid, 1,3-cyclopentanedicarboxylic acid, Terephthalic acid, Isophthalic acid, Phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalic acid, biphenyldicarboxylic acid, 1,2-bisphenoxyethane-p, p'-dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, one or more acid components such as anhydrides or ester-forming derivatives of these dicarboxylic acids, and polyesters obtained by dehydration condensation reaction as well as ε-caprolactone By ring-opening polymerization reaction of cyclic ester compounds such as Polyesters obtained from the above, or copolymerized polyesters thereof.
[0026]
Examples of the polyether polyol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6- Hexanediol, neopentyl glycol, glycerin, trimethylolethane, trimethylolpropane, sorbitol, sucrose, bisphenol A, bisphenol S, hydrogenated bisphenol A, aconitic acid, trimellitic acid, hemimellitic acid, phosphoric acid, ethylenediamine, diethylenetriamine, triethylene Has at least two active hydrogens such as isopropanolamine, pyrogallol, dihydroxybenzoic acid, hydroxyphthalic acid, 1,2,3-propanetrithiol One type of monomer such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, cyclohexylene, etc., starting from a compound or a compound having at least two primary amino groups such as ethylenediamine and propylenediamine Or the thing etc. which carried out addition polymerization by the conventional method using 2 or more types are mention | raise | lifted.
[0027]
Examples of the polycarbonate polyol include compounds obtained by reacting diols such as 1,4-butanediol, 1,6-hexanediol, and diethylene glycol with diphenyl carbonate and phosgene.
[0028]
Examples of the polyhydroxy compound (Cp) having a tertiary amino group before neutralization with an acid of the polyhydroxy compound (C) used in the present invention or quaternization with a quaternizing agent include the following general formula (I) ):
[0029]
[Chemical 1]

[0030]
(In the formula, R represents an alkyl group having 1 to 4 carbon atoms or a hydroxyalkyl group, and R ¹ and R ² may be the same or different, and each represents an alkylene group having 1 to 4 carbon atoms. ). The compound represented by the general formula (I) includes a diol compound having a tertiary amino group and a triol compound having a tertiary amino group. Among such compounds, diol compounds (compounds in which R is an alkyl group) include N-methyl-N, N-diethanolamine, N-ethyl-N, N-diethanolamine, N-isobutyl-N, N-diethanolamine. Examples of the triol compound (a compound in which R is a hydroxyalkyl group) include triethanolamine.
[0031]
In the present invention, a polyhydroxy compound (B) having at least two active hydrogen atoms reactive with an NCO group and a tertiary amino group neutralized with an acid in the molecule or quaternized with a quaternizing agent And a polyhydroxy compound (C) having at least two active hydrogen atoms reactive with the NCO group [or an activity having a tertiary amino group in the molecule and reactive with the NCO group The average active hydrogen concentration of the polyhydroxy compound (Cp) having at least two hydrogen atoms] is preferably 100 to 800 (mgKOH / g). When the average active hydrogen concentration is less than 100, the scratch resistance and heat resistance tend to be inferior. On the other hand, when it exceeds 800, the paper processing characteristics tend to deteriorate.
[0032]
Here, the average active hydrogen concentration of the polyhydroxy compound (B) and the polyhydroxy compound (C) is a value determined as follows. A polyhydroxy compound (B) having at least two active hydrogen atoms reactive with an NCO group is composed of components B1, B2... Bk (where k is an integer of 1 or more), and components B1, B2,. for ... Bk, active hydrogen concentration (mg KOH / g) is H _B1, H _B2 ...... H _BK respectively, the amount (g) is assumed to be respectively _{W B1, W B2 ...... W Bk} . Further, a polyhydroxy compound having a tertiary amino group neutralized with an acid or quaternized with a quaternizing agent in the molecule and having at least two active hydrogen atoms reactive with an NCO group ( C) is composed of components of C1, C2... Cm (where m is an integer of 1 or more), and the active hydrogen concentration (mgKOH / g) of components C1, C2... Cm is H _C1 and H _C2 , respectively. , H _Cm , and the usage (g) is W _C1 , W _C2 ... W _Cm , respectively. The average active hydrogen concentration for such a mixture of components B1, B2... Bk, components C1, C2.
[0033]
[Expression 2]

[0034]
Sought by.
[0035]
The average active hydrogen concentration of the polyhydroxy compound (B) and the polyhydroxy compound (Cp) is also determined in the same manner as described above.
[0036]
The cationic aqueous polyurethane resin of the present invention is
[I] (1) Organic polyisocyanate (A), polyhydroxy compound (B), polyhydroxy having a tertiary amino group in the molecule and having at least two active hydrogen atoms reactive with NCO groups Is it possible to obtain a urethane prepolymer by reacting with the compound (Cp) and then neutralize the tertiary amino group of the urethane prepolymer with an acid or quaternize with a quaternizing agent to obtain a cationic urethane prepolymer? Or (2) an organic polyisocyanate (A), a polyhydroxy compound (B), a tertiary amino group neutralized with an acid or quaternized with a quaternizing agent in the molecule, and an NCO group Of a cationic urethane prepolymer obtained by reacting a polyhydroxy compound (C) having at least two reactive active hydrogen atoms and a reactive urethane prepolymer And the extent,
[II] The cationic urethane prepolymer can be produced by a production method comprising a step of obtaining a cationic aqueous polyurethane resin by extending a chain with a polyamine compound.
[0037]
Examples of the acid used to neutralize the tertiary amino group include organic acids such as formic acid, acetic acid, propionic acid, butyric acid, lactic acid, malic acid and citric acid, and hydrochloric acid, phosphoric acid, phosphorous acid, nitric acid and the like. Examples include inorganic acids. Quaternizing agents include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin and other epoxy compounds, dimethyl sulfate and dialkyl sulfates such as diethyl sulfate, and alkyl sulfonates such as methyl paratoluenesulfonate. And alkyl halides such as methyl chloride, ethyl chloride, benzyl chloride, methyl bromide and ethyl bromide.
[0038]
When the organic polyisocyanate (A) is a highly reactive isocyanate such as an aromatic isocyanate, a urethane prepolymer is produced using a polyhydroxy compound (Cp) having a tertiary amino group in the step [I], When the method (1) for cationizing a tertiary amino group is employed, gelation or the like may occur. Therefore, a urethane prepolymer is produced using a polyhydroxy compound (C) having a cationized tertiary amino group. Method (2) is preferred.
[0039]
In step [I], the organic polyisocyanate (A), the polyhydroxy compound (B), and a tertiary amino group neutralized with an acid or quaternized with a quaternizing agent in the molecule, and , A polyhydroxy compound (C) having at least two active hydrogen atoms reactive with an NCO group [or a polyhydroxy compound (B) and a tertiary amino group in the molecule, and reactive with the NCO group A polyhydroxy compound (Cp)] having at least two active hydrogen atoms, preferably the equivalent of the isocyanate group of (A) and the equivalent of the active hydrogen atom of (B) and (C) [or (Cp)] The urethane prepolymer having a terminal isocyanate group is produced by reacting so that the total ratio is 1.0 / 1.0 to 1.0 / 0.5.
[0040]
In order to produce a cationic urethane prepolymer having a branch density of 0.08 to 0.25, a mixture of a diol and a polyol having 3 or more functional groups is used as the polyhydroxy compound (B). When a compound having 2 functional groups is used as (C) [or polyhydroxy compound (Cp)] and diisocyanate is used as the organic polyisocyanate, the branch density can be easily adjusted.
[0041]
The isocyanate polyaddition reaction in step [I] can be carried out in the absence of a solvent depending on the composition, but a hydrophilic organic solvent that does not directly participate in the isocyanate polyaddition reaction system is used for the purpose of suppressing the reaction of the reaction system or controlling the base viscosity. It is common to use it as a reaction solvent. Examples of such hydrophilic organic solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and diisobutyl ketone, methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate and methyl propionate. And organic acid esters such as ethyl propionate and butyl propionate, and amines such as N, N-dimethylformamide and N-methylpyrrolidone. The hydrophilic organic solvent used for the reaction is preferably finally removed.
[0042]
In step [II], the cationic urethane prepolymer obtained in step [I] is chain-extended with a polyamine compound. For example, after adding water to the cationic urethane prepolymer solution obtained in the step [I] and emulsifying it, a polyamine compound is added to cause chain elongation reaction, and then the solvent is removed. An emulsion is obtained. By chain extension with a polyamine compound, a high molecular weight polyurethane resin as described above can be easily obtained.
[0043]
Examples of the polyamine compound used as the chain extender include aliphatic diamine compounds having two primary amino groups such as ethylenediamine, trimethylenediamine, propylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine; tolylenediamine, xylene Aromatic diamine compounds having two primary amino groups such as diamine and diaminodiphenylmethane; alicyclic diamine compounds having two primary amino groups such as diaminocyclohexylmethane; piperazine derivatives such as piperazine and 2-methylpiperazine; isophoronediamine; Aliphatic polyamines having two primary amino groups and one or more secondary amino groups, such as diethylenetriamine, dipropylenetriamine, triethylenetetramine, tetraethylenepentamine Emissions compounds; hydrazine, di hydrazine derivative, such as adipic acid hydrazide; and a polyamine compound having a primary amino group three or more, such as melamine and the like.
[0044]
The average particle diameter of the cationic water-based polyurethane resin emulsion is preferably in the range of 0.001 to 0.1 μm from the viewpoint of permeability to paper.
[0045]
The ink jet recording paper coating agent of the present invention contains an emulsion of the cationic aqueous polyurethane resin, and is generally used for ink jet recording paper coating agents, such as water-soluble polymers and inorganic fillers. You may mix | blend various additives, such as. Examples of the water-soluble polymer include oxidized starch, polyvinyl alcohol, gelatin, polyvinyl pyrrolidone, polyacrylamide, sodium polyacrylate, casein, and carboxymethyl cellulose. Examples of inorganic fillers include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium oxide, zinc oxide, zinc sulfate, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate. And amorphous silica, aluminum hydroxide, alumina, lithopone and the like. Amorphous silica is preferred from the standpoint of printing speed and color developability.
[0046]
The content of the cationic water-based polyurethane resin in the coating agent for ink jet recording paper of the present invention is preferably 5% by weight or more from the viewpoint of sufficiently exerting its excellent performance.
[0047]
An ink jet recording paper is obtained by applying the ink jet recording paper coating agent of the present invention to a paper substrate. As the paper substrate, plain paper, coated paper, etc. can be used. The coating thickness after drying of the coating agent is suitably about 3 to 30 μm.
[0048]
【Example】
Next, the present invention will be described with reference to examples.
[0049]
The weight average molecular weight of the cationic polyurethane resin obtained in the following examples was obtained as a weight average molecular weight in terms of polyethylene glycol by determining the relative molecular weight distribution of the cationic polyurethane resin by GPC (gel permeation chromatography). The GPC measurement conditions are as follows.
[0050]
Measurement model: SC-8010 manufactured by Tosoh Corp. Column: Shodex Ohpak SB-G + Ohpak SB-806MHQ × 2 solution: DMF / 0.06M LiBr / 0.04MH ₃ PO ₃
Temperature: Column thermostat 40 ° C
Flow rate: 1.0 ml / min Concentration: 0.1 wt / Vol%
Injection volume: 100 μl
Solubility: Complete dissolution Pretreatment: 0.45 μm Filter detector: Differential refractometer
The active hydrogen concentration of the polyhydroxy compound used is determined as follows.
[0052]
Sample was sampled according to estimated active hydrogen concentration and weighed, then added 5 ml acetylating reagent (prepared by mixing 1 part by volume acetic anhydride and 2 parts by volume pyridine just before use) and heated for 10-15 minutes To acetylate. Thereafter, 2 ml of water is added and cooled, and the mixture is left for about 20 minutes to hydrolyze excess acetic anhydride. To this, 60 ml of neutral ethanol is added, 0.2 ml of phenolphthalein indicator is added, and titrated with a 1 mol / l potassium hydroxide standard solution.
[0053]
Active hydrogen concentration (mgKOH / g)
= [(B−S) × f × 56.11] / mass of sample (g) + AV
B: ml of 1 mol / l potassium hydroxide standard solution required for the blank test
S: ml of 1 mol / l potassium hydroxide standard solution required for the actual test
f: Potency of 1 mol / l potassium hydroxide standard solution AV: Acid value of the same sample
Example 1
300 parts by weight of polybutylene adipate diol (weight average molecular weight 2000, trade name NIPPOLAN 4010, manufactured by Nippon Polyurethane Industry Co., Ltd.), 9.0 parts by weight of trimethylolpropane (molecular weight 134), N-methyl-N, N-diethanolamine 49 Part by weight, 180 parts by weight of isophorone diisocyanate and 377 parts by weight of methyl ethyl ketone are placed in a reaction vessel and reacted for 90 minutes while maintaining at 70 to 75 ° C. Then, 38.1 parts by weight of dimethyl sulfate is added and reacted at 50 to 60 ° C. for 20 minutes. Thus, a cationic urethane polymer solution having an NCO content of 2.2% by weight was obtained. To this solution, 1370 parts by weight of water was added at a time under emulsification and emulsified. Immediately after that, a solution in which 8.4 parts by weight of ethylenediamine was dissolved in 40 parts by weight of water was added and reacted at 30 ° C. for 60 minutes for chain extension. Next, methyl ethyl ketone was distilled off to obtain an emulsion of a cationic polyurethane resin having a weight average molecular weight of 750,000 (solid content concentration 30% by weight, emulsion average particle size 0.03 μm). The average active hydrogen concentration of the polybutylene adipatediol, trimethylolpropane, and N-methyl-N, N-diethanolamine was 207 (mgKOH / g). The branch density of the cationic urethane prepolymer was 0.12.
[0055]
Example 2
Polyester diol obtained from 1,6-hexanediol and ethylene glycol, isophthalic acid and adipic acid (weight average molecular weight 1000, trade name TA-22-419A, manufactured by Hitachi Chemical Co., Ltd.) 240 parts by weight, trimethylolpropane (Molecular weight 134) 8.0 parts by weight, 41 parts by weight of N-methyl-N, N-diethanolamine, 180 parts by weight of isophorone diisocyanate, 310 parts by weight of methyl ethyl ketone are placed in a reaction vessel and reacted for 60 minutes while maintaining at 70 to 75 ° C. Next, 32.5 parts by weight of dimethyl sulfuric acid was added and reacted at 50-60 ° C. for 20 minutes to obtain a cationic urethane polymer solution having an NCO content of 2.3% by weight. To this solution, 1290 parts by weight of water was added all at once with emulsification, followed by emulsification. Immediately after that, a solution in which 7.7 parts by weight of ethylenediamine was dissolved in 40 parts by weight of water was added and reacted at 30 ° C. for 60 minutes for chain extension. Then, methyl ethyl ketone was distilled off to obtain an emulsion of a cationic polyurethane resin having a weight average molecular weight of 450,000 (solid content concentration 28% by weight, emulsion average particle size 0.02 μm). The average active hydrogen concentration of the polyester diol, trimethylolpropane, and N-methyl-N, N-diethanolamine was 261 (mgKOH / g). The branch density of the cationic urethane prepolymer was 0.13.
[0056]
Example 3
Ethylene oxide 2 mol adduct of bisphenol A (weight average molecular weight 330, trade name Newpol BPE-20NK, Sanyo Chemical Industries, Ltd.) 150 parts by weight, trimethylolpropane (molecular weight 134) 11 parts by weight, N-methyl- 44 parts by weight of N, N-diethanolamine, 300 parts by weight of 4,4′-dicyclohexylmethane diisocyanate and 450 parts by weight of methyl ethyl ketone are placed in a reaction vessel, reacted for 120 minutes while maintaining at 70 to 75 ° C., and then 32.7 parts by weight of dimethyl sulfate. Was added and reacted at 50 to 60 ° C. for 20 minutes to obtain a cationic urethane polymer solution having an NCO content of 3.1 wt%. To this solution, 1577 parts by weight of water was added at once with emulsification and emulsified. Immediately after that, a solution in which 11.2 parts by weight of ethylenediamine was dissolved in 50 parts by weight of water was added and reacted at 30 ° C. for 60 minutes for chain extension. Then, methyl ethyl ketone was distilled off to obtain an emulsion of a cationic polyurethane resin having a weight average molecular weight of 900,000 (solid content concentration 27% by weight, emulsion average particle size 0.04 μm). The average active hydrogen concentration of the bisphenol A ethylene oxide 2-mole adduct, trimethylolpropane and N-methyl-N, N-diethanolamine was 520 (mgKOH / g). The branch density of the cationic urethane prepolymer was 0.16.
[0057]
Example 4
A solution prepared by dissolving 39.6 parts by weight of N-methyl-N, N-diethanolamine and 175 parts by weight of methyl ethyl ketone in a reaction vessel and dissolving 41.9 parts by weight of dimethyl sulfate in 70 parts by weight of methyl ethyl ketone is gradually added dropwise to the reaction mixture. The quaternization reaction was performed at 50 ° C. for 10 minutes. In this reaction vessel, ethylene oxide 2-mole adduct of bisphenol A (weight average molecular weight 330, trade name Newpol BPE-20NK, Sanyo Chemical Industries Co., Ltd.) 123.8 parts by weight, trimethylolpropane (molecular weight 134) 9 .9 parts by weight, tolylene diisocyanate 175.8 parts by weight, and methyl ethyl ketone 350 parts by weight, reacted for 180 minutes while maintaining at 70 to 75 ° C., and a solution of a cationic urethane polymer having an NCO content of 4.4% by weight Got. To this solution, 912 parts by weight of water was added all at once with emulsification, and immediately after emulsification, a solution in which 31.8 parts by weight of adipic hydrazide was dissolved in 120 parts by weight of water was added and reacted at 30 ° C. for 30 minutes to chain-extend. Then, methyl ethyl ketone was distilled off to obtain an emulsion of a cationic polyurethane resin having a weight average molecular weight of 950,000 (solid content concentration 27 wt%, emulsion average particle size 0.04 μm). The average active hydrogen concentration of the ethylene oxide 2-mole adduct of bisphenol A, trimethylolpropane, and quaternized N-methyl-N, N-diethanolamine was 531 (mgKOH / g). The branch density of the cationic urethane prepolymer was 0.21.
[0058]
Example 5
7. 34 parts by weight of polytetramethylene glycol (weight average molecular weight 250, trade name TERATHANE250, manufactured by DuPont), 45.8 parts by weight of 1,4-cyclohexanedimethanol (molecular weight 144.2), trimethylolpropane (molecular weight 134) 9 parts by weight, 36 parts by weight of N-methyl-N, N-diethanolamine, 268 parts by weight of 4,4′-dicyclohexylmethane diisocyanate and 300 parts by weight of methyl ethyl ketone were placed in a reaction vessel and reacted for 120 minutes while maintaining at 70 to 75 ° C. Subsequently, 29.7 parts by weight of dimethyl sulfuric acid was added and reacted at 50 to 60 ° C. for 20 minutes to obtain a cationic urethane polymer solution having an NCO content of 3.6% by weight. To this solution, 1420 parts by weight of water was added all at once with emulsification, and immediately after emulsification, a solution in which 9.8 parts by weight of ethylenediamine was dissolved in 50 parts by weight of water was added and reacted at 30 ° C. for 60 minutes for chain extension. Then, methyl ethyl ketone was distilled off to obtain an emulsion of a cationic polyurethane resin having a weight average molecular weight of 750,000 (solid content concentration 26 wt%, emulsion average particle diameter 0.01 μm). The average active hydrogen concentration of the polytetramethylene glycol, 1,4-cyclohexanedimethanol, trimethylolpropane, and N-methyl-N, N-diethanolamine was 770 (KOHmg / g). Further, the branch density of the cationic urethane prepolymer was 0.17.
[0059]
Example 6
250 parts by weight of polycarbonate diol (weight average molecular weight 1000, trade name NIPPOLAN 981, manufactured by Nippon Polyurethane Industry Co., Ltd.), polyethylene glycol (weight average molecular weight 600, trade name PEG600S, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Trimethylolpropane (molecular weight 134) 7.0 parts by weight, N-methyl-N, N-diethanolamine 31 parts by weight, 4,4′-dicyclohexylmethane diisocyanate 200 parts by weight, and methyl ethyl ketone 400 parts by weight are placed in a reaction vessel. The mixture was reacted at 120 ° C. for 120 minutes, then 32 parts by weight of dimethyl sulfate was added, and reacted at 50-60 ° C. for 20 minutes to obtain a solution of a cationic urethane polymer having an NCO content of 2.5% by weight. . To this solution, 1320 parts by weight of water was added all at once with emulsification, and immediately after emulsification, a solution in which 8.9 parts by weight of ethylenediamine was dissolved in 50 parts by weight of water was added and reacted at 30 ° C. for 60 minutes for chain extension. Then, methyl ethyl ketone was distilled off to obtain an emulsion of a cationic polyurethane resin having a weight average molecular weight of 730,000 (solid content concentration 25% by weight, emulsion average particle size 0.03 μm). The average active hydrogen concentration of the polycarbonate diol, polyethylene glycol, trimethylolpropane, and N-methyl-N, N-diethanolamine was 228 (mgKOH / g). Further, the branch density of the cationic urethane prepolymer was 0.10.
[0060]
Comparative Example 1
Polytetramethylene glycol (weight average molecular weight 2000, trade name PTMG1000, manufactured by Mitsubishi Chemical Corporation) 238 parts by weight, N-methyl-N, N-diethanolamine 38.1 parts by weight, isophorone diisocyanate 137 parts by weight, methyl ethyl ketone 210 parts by weight In a reaction vessel and allowed to react for 150 minutes while maintaining at 70 to 75 ° C., then 32.3 parts by weight of dimethyl sulfuric acid was added and reacted at 50 to 60 ° C. for 20 minutes to obtain an NCO content of 2.0% by weight. A cationic urethane polymer solution was obtained. To this solution, 1155 parts by weight of water was added all at once with emulsification, followed by emulsification. Immediately after that, a solution in which 6.0 parts by weight of ethylenediamine was dissolved in 40 parts by weight of water was added and reacted at 30 ° C. for 60 minutes for chain extension. Then, methyl ethyl ketone was distilled off to obtain an emulsion of a cationic polyurethane resin having a weight average molecular weight of 620,000 (solid content concentration 30% by weight, emulsion average particle diameter 0.02 μm). The average active hydrogen concentration of the polytetramethylene glycol and N-methyl-N, N-diethanolamine was 227 (mgKOH / g). The branch density of the cationic urethane prepolymer was zero.
[0061]
Comparative Example 2
400 parts by weight of polyester diol (weight average molecular weight 4000, trade name HOKKUOL HT-400, manufactured by Toyokuni Oil Co., Ltd.), 24 parts by weight of trimethylolpropane (molecular weight 134), 18 parts by weight of N-methyl-N, N-diethanolamine, 150 parts by weight of isophorone diisocyanate and 592 parts by weight of methyl ethyl ketone are placed in a reaction vessel and reacted for 150 minutes while maintaining the temperature at 70 to 75 ° C. Then, 18.0 parts by weight of dimethyl sulfate is added and reacted at 50 to 60 ° C. for 20 minutes. A cationic urethane polymer solution having an NCO content of 3.2% by weight was obtained. To this solution, 1520 parts by weight of water was added at once with emulsification and emulsified. Immediately after that, a solution in which 6.0 parts by weight of ethylenediamine was dissolved in 40 parts by weight of water was added and reacted at 30 ° C. for 60 minutes for chain extension. Then, methyl ethyl ketone was distilled off to obtain an emulsion of a cationic polyurethane resin having a weight average molecular weight of 760,000 (solid content concentration 30% by weight, emulsion average particle size 0.15 μm). The average active hydrogen concentration of the polyester diol, trimethylolpropane, and N-methyl-N, N-diethanolamine was 132 (mgKOH / g). The branch density of the cationic urethane prepolymer was 0.29.
[0062]
Examples 7 to 12 and Comparative Examples 3 and 4
50 parts by weight of each of the cationic polyurethane resin emulsions obtained in Examples 1 to 6 and Comparative Examples 1 and 2 were blended with 50 parts by weight of amorphous silica and 200 parts by weight of a 20% by weight polyvinyl alcohol aqueous solution. A working solution was prepared, applied to high-quality paper with a bar coater so as to have a thickness of 25 μm, and dried at 100 ° C. for 3 minutes to obtain an ink jet recording paper.
[0063]
The obtained inkjet recording paper was evaluated for the following items. The results are shown in Table 1.
[0064]
(1) Ink fixability Evaluation was made based on the time until the ink no longer adheres when the printed image is printed on the coated surface of the inkjet recording paper with an inkjet printer (MACHJET MJ-830C, manufactured by Seiko Epson Corporation) and touches the recorded image. did.
Evaluation criteria ◎: Less than 20 seconds ○: 20-60 seconds ×: More than 60 seconds
(2) Water resistance Printing was carried out in the same manner as in (1) above, and one drop of water was dropped with a dropper at the boundary between the printing part and the non-printing part, and the bleeding of the printing was visually observed and evaluated.
Evaluation standard ◎: No bleeding ○: Slight bleeding (printing can be identified)
×: bleeding (printing cannot be identified)
[0066]
(3) Paper workability Cracks on the coated surface after applying and drying the coating liquid for inkjet recording paper were visually observed and evaluated.
Evaluation standard ◎: No crack ○: There is a crack within 2 mm ×: There is a crack exceeding 2 mm [0067]
(4) A4 size ink jet recording paper not subjected to scratch-resistant printing was evaluated by repeating paper feeding using an ink jet printer (MACHJET MJ-830C manufactured by Seiko Epson Corporation).
Evaluation criteria A: Very good (the coated surface is not damaged even when paper is fed 50 times)
○: Good (the coated surface is not damaged even when paper is fed 30 times)
Δ: Slightly good (scratches occur on the coated surface after 10 to 30 paper feeds)
X: Defect (scratches occur on the coated surface by feeding the paper less than 10 times)
[0068]
(5) Dimensional stability Solid printing was performed on the coated surface of the inkjet recording paper using an inkjet printer (MACHJET MJ-830C, manufactured by Seiko Epson Corporation), and evaluation was made by comparing the paper dimensions before printing with the paper dimensions after printing. (Compared by the rate of increase of the paper area after printing relative to the paper area before printing)
Evaluation standard ◎: Excellent (no dimensional change)
○: Good (within 1% dimensional change)
X: Defect (dimensional change exceeds 1%)
[0069]
(6) Heat resistance After color printing on the coated surface of the inkjet recording paper with an inkjet printer (MACHJET MJ-830C, manufactured by Seiko Epson Corporation), it is stored at 60 ° C. for 3 days, and the change in each color is visually observed and determined. did. This test examines the degree to which the inkjet recording paper coating agent affects the color of ink when stored at high temperatures.
Evaluation standard ◎: Excellent (no change at all)
○: Good (slight change is observed)
X: Defect (there is a level that has no change as an image)
[0070]
(7) Solvent resistance After printing on the coated surface of the inkjet recording paper with an inkjet printer (MACHJET MJ-830C, manufactured by Seiko Epson Corporation), evaluation was performed by lightly rubbing the printed surface with a cotton swab attached with methanol.
Evaluation standard ◎: Excellent (no cloudiness or dropout even after rubbing 50 times)
○: Good (no cloudiness or dropout even after rubbing 30 times)
Δ: Slightly inferior (10-30 times of rubbing, cloudiness, falling off)
X: Defect (fogging or falling off due to rubbing less than 10 times)
[0071]
[Table 1]

[0072]
【The invention's effect】
The coating agent for inkjet recording paper comprising the specific cationic water-based polyurethane resin of the present invention is not only ink fixability and water resistance, but also scratch resistance, dimensional stability during printing, heat resistance, solvent resistance, and inorganic filling. Excellent binder ability for the agent.

Claims (7)

(A) a structural unit derived from an organic polyisocyanate; (B) a structural unit derived from a polyhydroxy compound having at least two active hydrogen atoms reactive with an NCO group; and (C) an acid in the molecule. A structural unit derived from a polyhydroxy compound having a tertiary amino group neutralized with or quaternized with a quaternizing agent and having at least two active hydrogen atoms reactive with an NCO group; And an emulsion of a cationic water-based polyurethane resin obtained by chain-extending a cationic urethane prepolymer having a branch density of 0.08 to 0.25 per 1000 atomic weight with a polyamine compound. Agent. The coating agent for inkjet recording paper according to claim 1, wherein the average active hydrogen concentration of the polyhydroxy compound (B) and the polyhydroxy compound (C) is from 100 to 800 (mgKOH / g). The coating agent for inkjet recording paper according to claim 1 or 2, wherein an average particle size of the emulsion of the cationic aqueous polyurethane resin is 0.001 to 0.1 µm. The cationic urethane prepolymer has an organic polyisocyanate (A), a polyhydroxy compound (B), a tertiary amino group in the molecule, and at least two active hydrogen atoms reactive with an NCO group. It is obtained by reacting with a polyhydroxy compound (Cp) to obtain a urethane prepolymer, and then neutralizing the tertiary amino group of the urethane prepolymer with an acid or quaternizing with a quaternizing agent. The coating agent for inkjet recording paper in any one of Claims 1-3. When the organic polyisocyanate (A) is an aromatic polyisocyanate, the cationic urethane prepolymer is neutralized or quaternized with an organic polyisocyanate (A), a polyhydroxy compound (B), an acid in the molecule A product obtained by reacting a polyhydroxy compound (C) having a tertiary amino group quaternized with an agent and having at least two active hydrogen atoms reactive with an NCO group. The coating agent for inkjet recording papers in any one of 1-3. The coating agent for inkjet recording paper according to any one of claims 1 to 5, wherein the cationic aqueous polyurethane resin has a weight average molecular weight of 100,000 to 1,000,000. An ink jet recording paper obtained by coating the coating agent according to any one of claims 1 to 6 on a paper substrate.