JP3889866B2 - Polyurethane resin-based photocurable coating agent and photocurable composition - Google Patents

Description

【００１６】
（式中、Ｒ¹及びＲ²は、同一又は異なって、それぞれ水素原子、低級アルキル又は低級アルコキシ基を示す）。
【００１７】
さらに本発明は、（２）前記ポリウレタン樹脂の重量平均分子量が１，０００〜２００，０００の範囲にあることを特徴とする前記（１）項記載の光硬化性被覆剤に関する。
【００１８】
さらに本発明は、（３）前記ポリウレタン樹脂に加えて、ラジカル重合性不飽和結合を有する化合物を含有することを特徴とする前記（１）または（２）項記載の光硬化性被覆剤に関する。
【００１９】
さらに本発明は、（４）前記ポリウレタン樹脂が水に溶解または分散され、水性化された被覆剤であることを特徴とする前記（１）、（２）または（３）項記載の光硬化性被覆剤に関する。
【００２０】
さらに本発明は、（５）前記ポリウレタン樹脂が分子中に少なくとも１個のヒドラジン残基を有することを特徴とする前記（１）〜（４）項のいずれかに記載の光硬化性被覆剤に関する。
【００２１】
さらに本発明は、（６）前記ポリウレタン樹脂中のケト形及び／又はアルデヒド形由来のカルボニル基の当量に対して、ヒドラジン残基が０．０５〜３．０当量の範囲になる量のヒドラジン化合物が配合されてなることを特徴とする前記（１）〜（５）項のいずれかに記載の光硬化性被覆剤に関する。
【００２２】
さらに本発明は、（７）ベンゾフェノンテトラカルボン酸化合物から誘導される下記一般式（Ｉ）で示される構造と、ウレタン結合及び／又はウレア結合とを有し、かつ数平均分子量が２０００以下のラジカル重合性不飽和結合を含む基がベンゾフェノンテトラカルボン酸化合物由来のカルボキシル基と結合しているポリウレタン樹脂であって、下記一般式（Ｉ）で示される構造を該樹脂中に３重量％以上含むポリウレタン樹脂からなり、前記ポリウレタン樹脂が、ポリウレタン樹脂中の下記一般式（Ｉ）で示される構造が組成物全量中に０．０１重量％以上になる割合で含有されてなることを特徴とする光硬化性組成物に関する。
【００２３】
【化４】

【００２４】
（式中、Ｒ¹及びＲ²は、同一又は異なって、それぞれ水素原子、低級アルキル又は低級アルコキシ基を示す）。
【００２５】
さらに本発明は、（８）前記ポリウレタン樹脂の重量平均分子量が１，０００〜２００，０００の範囲にあることを特徴とする前記（７）項記載の光硬化性組成物に関する。
【００２６】
さらに本発明は、（９）前記ポリウレタン樹脂に加えて、ラジカル重合性不飽和結合を有する化合物を含有することを特徴とする前記（７）または（８）項記載の光硬化性組成物に関する。
【００２７】
さらに本発明は、（１０）前記ポリウレタン樹脂が水に溶解または分散され、水性化された組成物であることを特徴とする前記（７）、（８）または（９）項記載の光硬化性組成物に関する。
【００２８】
さらに本発明は、（１１）前記ポリウレタン樹脂が分子中に少なくとも１個のヒドラジン残基を有することを特徴とする前記（７）〜（１０）項のいずれかに記載の光硬化性組成物に関する。
【００２９】
さらに本発明は、（１２）前記ポリウレタン樹脂中のケト形及び／又はアルデヒド形由来のカルボニル基の当量に対して、ヒドラジン残基が０．０５〜３．０当量の範囲になる量のヒドラジン化合物が配合されてなることを特徴とする前記７）〜（１１）項のいずれかに記載の光硬化性組成物に関する。
【００３０】
【発明の実施の形態】
本発明において、被覆剤とは、木工コーティング、塩化ビニル系樹脂床コーティング、フィルムコーティング、光ファイバーコーティングなどに用いられる塗料（ワニスを含む）、平版印刷、スクリーン印刷、金属印刷などに用いられる印刷インキなどの、物品の表面に適用される各種被覆剤のみならず、塗料の下塗層に利用されるプライマー、光ディスク、プラスチックレンズなどに用いられる各種接着剤などをも包含する概念である。
【００３１】
本発明において、組成物とは前記被覆剤としての用途のみならず、印刷樹脂版、光造形材料などの樹脂成形体用組成物、ドライフィルムレジスト、液状レジスト、着色レジスト、半導体レジストなどの用途に使用されるものをも含む概念である。
【００３２】
以下、本発明を詳しく説明する。
【００３３】
本発明で使用するポリウレタン樹脂は、ベンゾフェノンテトラカルボン酸化合物から誘導される前記一般式（Ｉ）で示される構造と、ウレタン結合及び／又はウレア結合とを有し、かつ数平均分子量が２０００以下のラジカル重合性不飽和結合を含む基がベンゾフェノンテトラカルボン酸化合物由来のカルボキシル基と結合しているポリウレタン樹脂であって、前記一般式（Ｉ）で示される構造を該樹脂中に３重量％以上含むポリウレタン樹脂からなる。一般式（Ｉ）において、Ｒ¹、Ｒ²で示される低級アルキル基としては、たとえばメチル、エチルなどがあげられ、低級アルコキシ基としては、たとえばメトキシ、エトキシなどがあげられる。一般式（Ｉ）で示される構造としては、通常Ｒ¹及びＲ²が共に水素原子であるものが好ましい。
【００３４】
本発明のポリウレタン樹脂は、通常、ベンゾフェノンテトラカルボン酸化合物と、ジ（ポリ）オール成分及び／又はジ（ポリ）アミン化合物と、有機ジ（ポリ）イソシアナート化合物との反応によって主鎖が形成されており、さらに数平均分子量が２０００以下のラジカル重合性不飽和結合を含む基がベンゾフェノンテトラカルボン酸化合物の４つのカルボキシル基のうち主鎖の形成に関与していないカルボキシル基の少なくとも１つに結合されている。なお、数平均分子量が２０００以下のラジカル重合性不飽和結合を含む基はウレタン結合及び／又はウレア結合を含んでいてもよい。
【００３５】
なお、前記ベンゾフェノンテトラカルボン酸化合物とは、前記一般式（Ｉ）において、中央のカルボニル基を除いた４つのカルボニル基がカルボキシル基である化合物、およびそれらの酸無水物をいう。このベンゾフェノンテトラカルボン酸化合物には、たとえばベンゾフェノンテトラカルボン酸、２，２′−ジメチルベンゾフェノンテトラカルボン酸、２，２′−ジメトキシベンゾフェノンテトラカルボン酸、及びこれらの酸無水物等が含まれる。
【００３６】
本発明で使用するポリウレタン樹脂は、たとえばつぎの方法により得ることができる。
【００３７】
（Ａ）ベンゾフェノンテトラカルボン酸化合物と、ジ（ポリ）オール（ジオール及び／又はポリオールを意味する、以下同様）とのエステル化反応によって得られるジ（ポリ）オール化合物（一般式（Ｉ）で示される構成単位を１または２以上含む）と、有機ジ（ポリ）イソシアナート、必要に応じて鎖伸長剤、反応停止剤を使用して従来公知の方法で反応させてポリウレタン樹脂を得、このポリウレタン樹脂中の前記ベンゾフェノンテトラカルボン酸化合物に由来するカルボキシル基の一部又は全部を、これと反応し得る基とラジカル重合性不飽和基を併せ持つ化合物（以下、便宜上、不飽和変性剤という場合がある）、例えば水酸基、アミノ基、エポキシ基、イソシアナート基等を有する（メタ）アクリレート化合物、アリル化合物、ビニル化合物等と反応させる。
【００３８】
この方法においては、前記ジ（ポリ）オール化合物にかえて又はこれと併用して、前記ベンゾフェノンテトラカルボン酸化合物とジ（ポリ）アミン（ジアミン及び／又はポリアミンを意味する、以下同様）とのアミド化もしくはイミド化反応によって得られるジ（ポリ）アミン化合物を使用することができる。
【００３９】
前記方法においては、通常、前記ジ（ポリ）オール化合物及び／又はジ（ポリ）アミン化合物を、有機ジ（ポリ）イソシアナートに対して当量比で過剰量用いて、末端がジ（ポリ）オール化合物又はジ（ポリ）アミノ化合物になるようにする。
【００４０】
（Ｂ）前記ジ（ポリ）オール化合物及び／又はジ（ポリ）アミン化合物（これらは一般式（Ｉ）で示される構成単位を１又は２以上含む）に対して、有機ジ（ポリ）イソシアナートを当量比で過剰量用いて末端イソシアナート含有ウレタンプレポリマーを得、このウレタンプレポリマー中の前記ベンゾフェノンテトラカルボン酸化合物に由来するカルボキシル基の一部又は全部と前記不飽和変性剤と反応させ、これを鎖伸長剤を用いて鎖伸長させ、得られる末端イソシアナート含有ポリウレタンに反応停止剤を反応させてもよい。この場合は用いる反応停止剤の種類によって、末端に各種の基を導入できる。たとえば低級アルコール類、アルキルアミン類、ジアルキルアミン類を反応させるとアルキル基を導入でき、アルカノールアミンを反応させると水酸基を導入でき、エチレンジアミン等を反応させるとアミノ基を導入できる。
【００４１】
（Ｃ）前記ジ（ポリ）オール化合物及び／又はジ（ポリ）アミン化合物（これらは一般式（Ｉ）で示される構成単位を１又は２以上含む）に対して、有機ジ（ポリ）イソシアナートを当量比で過剰量用いて末端イソシアナート含有ウレタンポリマーを得、該末端イソシアナートと不飽和変性剤とを反応させる。
【００４２】
（Ｄ）前記ベンゾフェノンテトラカルボン酸化合物と前記不飽和変性剤とを、ベンゾフェノンテトラカルボン酸化合物に由来するカルボキシル基が残存する当量比で反応させてえられたベンゾフェノンテトラカルボン酸誘導体と、両末端水酸基のポリウレタンあるいは両末端アミノ基のポリウレタン（ジ（ポリ）オール及び／又はジ（ポリ）アミンと有機ジ（ポリ）イソシアナートを反応されて得られる）とを反応させる。
【００４３】
本発明のポリウレタン樹脂を構成する各成分についてより具体的に説明する。
【００４４】
前記ジ（ポリ）オールとしては、エチレングリコール、プロピレングリコール、ジエチレングリコール、ジプロピレングリコール、ポリエチレングリコール、ポリプロピレングリコール等の（ポリ）アルキレングリコール類、グリセリン、ジグリセリン、ポリグリセリン等のグリセリン類、トリメチロールプロパン、ペンタエリスリトール、ジペンタエリスリトールなどの多価アルコール類、ポリオキシアルキレンジ（ポリ）オール、ポリアルキレンアジペートジ（ポリ）オール、ポリカプロラクトンジ（ポリ）オール、ポリオレフィンジ（ポリ）オール、ポリカーボネートジ（ポリ）オール等が挙げられる。
【００４５】
前記ジ（ポリ）アミンとしては、エチレンジアミン、プロピレンジアミン、ダイマージアミン、ジエチレントリアミン等のアルキレンジ（ポリ）アミン類、イソホロンジアミン、ノルボルネンジアミン等の脂環族ジアミン類、ポリオキシアルキレンジアミン等が挙げられる。
【００４６】
前記ジ（ポリ）オールおよびジ（ポリ）アミンとしては、数平均分子量が５０００以下のものが好ましい。数平均分子量が５０００より大きいと、ポリウレタン樹脂中の一般式（Ｉ）で示される構成単位の割合を３重量％以上に維持するのが難しくなり、ラジカル重合開始剤としての性能が低下し、好ましくない。
【００４７】
有機ジ（ポリ）イソシアナートとしては、トリレンジイソシアナート、ジフェニルメタンジイソシアナナート等の芳香族ジイソシアナート類、キシリレンジイソシアナート、テトラメチルキシリレンジイソシアナート等の芳香脂肪族ジイソシアナート類、イソフォロンジイソシアナート、水添ジフェニルメタンジイソシアナート、水添キシリレンジイソシアナート等の脂環族ジイソシアナート類、ヘキサメチレンジイソシアナート、２，４，４−トリメチルヘキサメチレンジイソシアナート等の脂肪族ジイソシアナート類、及びこれらの２量体、３量体等が挙げられる。
【００４８】
鎖伸長剤としては、エチレングリコール、プロピレングリコール、ネオペンチルグリコール等の低分子グリコール類、エチレンジアミン、プロピレンジアミン、イソホロンジアミン、ジシクロヘキシルメタンジアミン、ジエチレントリアミン、トリエチレンジアミン等のポリアミン類、後述するヒドラジン化合物等が挙げられる。また一般式（II）で示されるカルボキシル基を有するグリコール等が挙げられる。
【００４９】
【化５】

【００５０】
（式中、Ｒ³は水素原子又は炭素数１〜８の直鎖又は分岐状のアルキル基を示す）。
【００５１】
反応停止剤としては、メチルアルコール、エチルアルコール等の低級アルコール類、ｎ−プロピルアミン、ｎ−ブチルアミン等のモノアルキルアミン類、ジエチルアミン、ジ−ｎ−プロピルアミン、ジ−ｎ−ブチルアミン等のジアルキルアミン類、モノエタノールアミン、ジエタノールアミン等のアルカノールアミン類、その他エチレンジアミン、ジエチレントリアミン、ヒドラジン等が例示できる。
【００５２】
前記不飽和変性剤としては、数平均分子量が２０００以下のものが好ましい。不飽和変性剤の数平均分子量が２０００より大きいと、ラジカル重合性が低下し、所望の硬化性能を発揮しがたくなる傾向がある。
【００５３】
前記水酸基を有する不飽和変性剤としては、たとえば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、４−ヒドロキシブチル（メタ）アクリレート、２−ヒドロキシアミル（メタ）アクリレート、２−ヒドロキシヘキシル（メタ）アクリレート、３−クロロ−２−ヒドロキシプロピル（メタ）アクリレート等のヒドロキシアルキル（メタ）アクリレート類、ポリアルキレングリコールモノ（メタ）アクリレート、ポリカプロラクトンジオールモノ（メタ）アクリレート等のポリオールのモノ（メタ）アクリレート類、アリルアルコール、グリコールとラジカル重合性イソシアナート化合物との付加体等が挙げられる。
【００５４】
アミノ基を有する不飽和変性剤としては、たとえばアリルアミン等が挙げられる。
【００５５】
エポキシ基を有する不飽和変性剤としては、たとえばグリシジル（メタ）アクリレート、２，３−エポキシ−２−メチルプロピル（メタ）アクリレート、６，７−エポキシ−ビシクロ［４，３，０］ノニル（メタ）アクリレート等の（メタ）アクリレート類、グリシジルビニルエーテル、アリルグリシジルエーテル等のビニルエーテル類、エポキシ変性ポリブタジエンなどのラジカル重合性エポキシ化合物等が挙げられる。
【００５６】
イソシアナート基を有する不飽和変性剤としては、たとえばｍ−イソプロペニルジメチルベンジルイソシアナート、メタクリロイルイソシアナート等が挙げられる。
【００５７】
本発明の良好な実施態様である前記ポリウレタン樹脂の分子中に少なくとも１個のヒドラジン残基を有する光重合開始剤を製造する方法としては、例えば、反応停止剤としてヒドラジン化合物を用いることによって実施することができる。
【００５８】
前記ヒドラジン化合物としては、ヒドラジン、及び下記一般式（III）で示される、アルキレンジヒドラジンならびに飽和脂肪族二塩基酸及び不飽和二塩基酸のジヒドラジド化合物、さらに、これらヒドラジン化合物をブロック化剤としたブロックドイソシアナートあるいはポリウレタン樹脂などが挙げられる。
【００５９】
Ｈ₂Ｎ−ＮＨ−Ｙ−ＮＨ−ＮＨ₂ （III）
（式中、Ｙは炭素数１〜８のアルキレン基、あるいは炭素数１〜１０の飽和又は不飽和二塩基酸の残基を表わす）。
【００６０】
より具体的にはアルキレンジヒドラジンとして、メチレンジヒドラジン、エチレンジヒドラジン、プロピレンジヒドラジン、ブチレンジヒドラジン等を挙げることができる。飽和脂肪族二塩基酸のジヒドラジド化合物としては、シュウ酸ジヒドラジド、マロン酸ジヒドラジド、コハク酸ジヒドラジド、グルタル酸ジヒドラジド、アジピン酸ジヒドラジド、アゼライン酸ジヒドラジド、セバシン酸ジヒドラジドなどを挙げることができる。不飽和二塩基酸のジヒドラジド化合物としては、フタル酸ジヒドラジド、フマル酸ジヒドラジド、イタコン酸ジヒドラジド等が挙げられる。
【００６１】
ヒドラジン残基を有するポリウレタン樹脂とすることで、光硬化反応とは別個に、ヒトラジン残基と、ケト形及び／又はアルデヒド形由来のカルボニル基との反応が起こり、硬化が促進され、より高機能な皮膜がえられるという効果がある。あるいは本発明の被覆剤又は組成物を接着剤等として使用するばあい、基材の表面にケト形及び／又はアルデヒド形由来のカルボニル基があればより強固な接着効果を示す。
【００６２】
本発明のポリウレタン樹脂を水溶性又は水分散性にするには、酸価が１０ｍｇＫＯＨ／ｇ以上、好ましくは１５ｍｇＫＯＨ／ｇ以上となるように反応成分を選択すればよい。また、ポリエチレングリコールのようなエチレンオキサイド鎖を有する化合物をジ（ポリ）オール成分として選択することによって水溶性又は水分散性にすることが可能となる。
【００６３】
本発明のポリウレタン樹脂は、分子中に一般式（Ｉ）で示される構造の構成単位が３重量％以上含まれていることが必要であり、好ましくは１０重量％以上である。一般式（Ｉ）の構成単位の含有量が前記範囲未満では充分な硬化性能が得られない。
【００６４】
本発明のポリウレタン樹脂の重量平均分子量は１，０００〜２００，０００の範囲にあることが好ましく、より好ましくは１，０００〜１００，０００である。分子量が前記範囲未満では安定して製造することがやや難しく、一方前記範囲を超えると樹脂を単独で使用する場合に塗工適性が不十分となることがある。
【００６５】
また、本発明におけるポリウレタン樹脂は光重合開始機能とラジカル重合機能を併せ持っているため、本発明の光硬化性被覆剤又は組成物の全量を該ポリウレタン樹脂の１種又は２種以上の混合物のみで構成することができる。
【００６６】
また本発明におけるポリウレタン樹脂は、他のラジカル重合性不飽和結合を有する化合物と併用することができ、それによって硬化性能をより向上することができる。
【００６７】
本発明において、前記ポリウレタン樹脂をラジカル重合性不飽和結合を有する化合物と併用し、組成物として使用するばあい、前記ポリウレタン樹脂を組成物全量に対して、一般式（Ｉ）で示される構成単位が０．０１重量％以上となる量で使用する必要があり、好ましくは０．０５重量％以上、さらに好ましくは０．１重量％以上である。一般式（Ｉ）で示される構成単位の量が前記範囲未満では充分な硬化性能が得られない。一方該構成単位の量が３０重量％を超えると、相対的にラジカル重合性不飽和結合を有する化合物の量が減少し、硬化物の特性を低下させる惧れがある。
【００６８】
本発明で任意成分として用いられるラジカル重合性不飽和結合を有する化合物としては、従来より公知のビニルエーテル類、アリル基を有する化合物、（メタ）アクリレート類、ビニルエステル類等のモノマー、それらのオリゴマー及びそれらのポリマー等がとくに制限なく使用できる。
【００６９】
また、水性化した光硬化性被覆剤又は組成物に用いる場合は、水溶性あるいは水分散可能なラジカル重合性不飽和結合を有する化合物であれば特に制限なく、従来より公知の側鎖あるいは末端に水酸基、カルボキシル基、アミノ基、アミド基、スルホン酸基、リン酸基あるいはポリオキシエチレン鎖等の親水性基と、（メタ）アクリロイル基、ビニル基、アリル基等のラジカル重合性基とを共に有する化合物、及びこれらの塩化合物であるモノマーあるいはオリゴマーが使用できる。
【００７０】
前記ラジカル重合性不飽和結合を有する化合物の具体例としては、たとえばつぎのものが挙げられる。
【００７１】
ビニルエーテル類としては、２−エチルヘキシルビニルエーテル、ｔｅｒｔ−アミルビニルエーテル、ドデシルビニルエーテル、オクタデシルビニルエーテル、エチレングリコールブチルビニルエーテル、トリエチレングリコールメチルビニルエーテル等の単官能のビニルエーテル類、ジエチレングリコールジビニルエーテル、ブタンジオールジビニルエーテル、ヘキサンジオールジビニルエーテル、シクロヘキサンジメタノールジビニルエーテル、エチレングリコールジビニルエーテル、テトラエチレングリコールジビニルエーテル等の多官能のビニルエーテル類等がある。
【００７２】
アリル基を有するモノマーとしては、２−エチルヘキシルアリルエーテル、ｔｅｒｔ−アミルアリルエーテル、ドデシルアリルエーテル、オクタデシルアリルエーテル、エチレングリコールブチルアリルエーテル、トリエチレングリコールメチルアリルエーテル等のアリルエーテル類、アリルアルコール、酢酸アリル等の単官能のモノマー、フタル酸ジアリル等の多官能のモノマー等がある。
【００７３】
（メタ）アクリレート類としては、メチル（メタ）アクリレート、エチル（メタ）アクリレート、ブチル（メタ）アクリレート等のアルキル（メタ）アクリレート類、（メタ）アクリルアミド等の単官能の（メタ）アクリレート類、１，６−ヘキサンジオールジ（メタ）アクリレート、トリプロピレングリコールジ（メタ）アクリレート、ビスフェノールＡジ（メタ）アクリレート、メチレンビス（メタ）アクリルアミド、トリメチロールプロパントリ（メタ）アクリレート、グリセリントリ（メタ）アクリレート等の多官能（メタ）アクリレート等がある。
【００７４】
ビニルエステル類としては、酢酸ビニル、プロピオン酸ビニル、酪酸ビニル、安息香酸ビニル等がある。
【００７５】
含窒素不飽和モノマーとしては、Ｎ−ビニルピロリドン、Ｎ−ビニルカルバゾール、Ｎ−ビニルアセトアミド、ビニルピリジン等がある。
【００７６】
カルボキシル基含有不飽和モノマーとしては、（メタ）アクリル酸、マレイン酸、マレイン酸ハーフエステル、フマル酸、フマル酸ハーフエステル等、及びその塩類がある。
【００７７】
水酸基含有不飽和モノマーとしては、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、４−ヒドロキシブチル（メタ）アクリレート、３−クロロ−２−ヒドロキシプロピル（メタ）アクリレート等がある。
【００７８】
その他のモノマーないしオリゴマーとしては、ブチルイソシアナート、フェニルイソシアナート等のイソシアナートと上記水酸基含有モノマーとの付加物、リン酸と上記水酸基含有モノマーとの付加物、多価アルコールとアルキレンオキサイドとの付加物に（メタ）アクリル酸を反応せしめた生成物等、ブタジエン、イソプレンなどのジエン類の低分子量重合体等がある。さらに、エチレン性不飽和基含有ポリウレタン樹脂、エチレン性不飽和基含有エポキシ樹脂、エチレン性不飽和基含有アクリル樹脂、エチレン性不飽和基含有シリコン樹脂、エチレン性不飽和基含有メラミン樹脂等がある。
【００７９】
これらのラジカル重合性不飽和結合を有する化合物の使用に際しては、目的に応じて単独であるいは２種以上を混合して使用でき、また他の光重合開始剤や増感剤との併用も可能である。
【００８０】
また、本発明の光硬化性被覆剤又は組成物中において、ポリウレタン樹脂とラジカル重合性不飽和結合を有する化合物とを併用する場合は、両者の合計量に対して、前者が０．５〜９５重量％、より好ましくは１〜９０重量％、後者が５〜９９．５重量％、より好ましくは１０〜９９重量％である。ポリウレタン樹脂中の一般式（Ｉ）の構成単位の重量割合にもよるが、ポリウレタン樹脂の使用量が前記範囲未満では光重合開始剤としての機能が充分に発揮されず、充分な硬化性能が得られない傾向がある。また、前記範囲を超えると、相対的にラジカル重合性不飽和結合を有する化合物の量が減少し、充分な硬化性能が得られない傾向がある。
【００８１】
本発明の光硬化性被覆剤又は組成物において、溶剤としては、有機溶剤を使用してもよいが、できるだけ使用しないのが好ましく、使用するばあいは水可溶性有機溶剤を使用するのが好ましい。水可溶性有機溶剤としては、たとえばメチルアルコール、エチルアルコール、プロピルアルコール、エチルセロソルブ、ブチルセロソルブ、エチルカービトール、ブチルカービトール、メトキシプロパノール、Ｎ−メチル−２−ピロリドン、アセトン等が挙げられる。
【００８２】
本発明の他の目的は、環境や人体に悪影響の少ない、水で希釈可能でかつ可視光で硬化できる光硬化性被覆剤又は組成物を提供することにある。
【００８３】
このような水性化された光硬化性被覆剤又は組成物を調製するには、ポリウレタン樹脂として、前述した水溶性又は水分散性のポリウレタン樹脂をそのまま水に溶解させるか、あるいは分散させて使用することができる。また、ラジカル重合性不飽和結合を有する化合物を併用する場合は、当該化合物として、前述した化合物のうち水溶性もしくは水分散性を有するものを適宜選択使用すればよい。前記ポリウレタン樹脂及び／又はラジカル重合性不飽和結合を有する化合物を水に溶解あるいは分散させる際に、必要に応じて界面活性剤や塩基性物質を使用することができる。前記界面活性剤としては、たとえばポリオキシエチレンアルキルフェニルエーテル、ポリオキシエチレンアルキルエーテル、アルキルナフタレンスルホン酸、ポリオキシエチレンアルキルアミン等が挙げられる。前記塩基性物質としては、たとえばアンモニア、トリエチルアミン、トリエタノールアミン、モルフォリン等の有機アミン、水酸化ナトリウム、水酸化カリウム等の無機アルカリ等が挙げられる。
【００８４】
溶剤としては水が使用されるが、必要に応じて前記水可溶性有機溶剤を少量配合してもよい。
【００８５】
また、一般に、光ラジカル反応による硬化は酸素の存在によって反応が阻害されたり、あるいは塗膜の膜厚が厚い場合は、その硬化にムラが生じ、目的とする硬化皮膜が得られないことがある。そこで、こうした問題を解決するために、従来においては、他の硬化剤、例えば、イソシアナート系硬化剤、シランカップリング剤等を組み合わせて使用している。しかし、こうした硬化方法は加熱が必要であったり、混合物そのものが不安定となったりする問題点を抱えていた。
【００８６】
これに対して、本発明のより好ましい実施態様であるヒドラジン化合物を配合してなる水性化された光硬化性被覆剤又は組成物は、水の存在下ではヒドラジン化合物と前記ポリウレタン樹脂中のケト形およびアルデヒド形由来のカルボニル基との反応を水が阻害しているため、混合物は安定に存在する。そして、この硬化性組成物を塗膜化すると、塗膜表面からの水分蒸発にしたがってヒドラジン化合物とポリウレタン樹脂中のケト形およびアルデヒド形由来のカルボニル基との反応が開始され、一方でこの塗膜に可視光を照射すると、光ラジカル重合による硬化が同時に進行する。これによって光硬化で発生する硬化ムラを補い、より高性能な、例えば、耐溶剤性能を有する硬化皮膜や、表面硬度の高い硬化皮膜を形成することができる。
【００８７】
光硬化性被覆剤又は組成物中におけるヒドラジン化合物の使用量は、前記ポリウレタン樹脂中のケト形及び／又はアルデヒド形由来のカルボニル基に対して、ヒドラジン残基が０．０５〜３．０当量の範囲であることが好ましい。ヒドラジン残基が０．０５当量より少ないと高性能な硬化皮膜が形成されず、一方３．０当量を超えて配合してもやはり分子間での架橋ができず、高性能な硬化皮膜が形成されない。この点から、ヒドラジン残基の使用量は、０．５〜１．５当量の範囲がより好ましい。
【００８８】
前記ヒドラジン化合物としては、前述のヒドラジン残基を有するポリウレタン樹脂の製造で使用したヒドラジン化合物が使用できる。
【００８９】
本発明の光硬化性被覆剤又は組成物には、以上で述べた各成分のほかに、ハイドロキノン、カテコール、ピクリン酸などの重合禁止剤、その他レベリング剤や消泡剤等を硬化性能に影響しない範囲で適宜加えることができる。また、他の光重合開始剤や、重合を促進するための増感剤、各種有機、無機の着色剤、体質顔料など従来公知の各種添加剤を硬化性能に影響しない範囲で目的に応じ適宜加えることができる。これらの添加剤は、それらの総量が被覆剤又は組成物中に０．１〜２０重量％程度になる程度で使用するのが好ましい。
【００９０】
本発明の光硬化性被覆剤又は組成物は、以上で述べた各成分をディスパ等の撹拌機を用いて室温下で均一に混合することによって得ることができる。
【００９１】
本発明の光硬化性被覆剤又は組成物は、光を遮断できる容器に入れ、冷暗所に保存するのが好ましい。
【００９２】
本発明におけるポリウレタン樹脂を光重合開始剤として使用する場合の重合を開始するメカニズムは必ずしも明確ではないが、一般式（Ｉ）で示される構造において中心に位置するカルボニル基が吸収した光エネルギーによって励起され、周辺に存在する活性水素を有する化合物から水素を引き抜き、その際生成するラジカル種が重合開始に寄与しているものと推定されている。
【００９３】
本発明の光硬化性被覆剤又は組成物の硬化方法としては、被覆剤であれば各種塗工機を用いて基材上に塗布した後、硬化させるに有効な量の可視光線を照射すればよい。また、本発明の被覆剤又は組成物を透明シートの接着剤として使用する場合は、本発明の被覆剤又は組成物を一方の基材に塗布した後、もう一方の基材をあわせ、被覆剤又は組成物を硬化させるに有効な量の可視光線を照射すればよい。さらには、建築物の外壁塗料などに使用される場合は、外壁材に塗布した後、そのまま太陽光に暴露することによって硬化させることができる。
【００９４】
光源としては有効量の可視光を照射することができるものであれば特に制限されず、例えば太陽光、ハロゲンランプ、白熱ランプ、炭素アーク、水銀蒸気アーク、高圧水銀ランプ、メタルハライドランプ、キセノンランプ、可視光レーザー等が使用できる。更に電離性放射線も使用できる。
【００９５】
【実施例】
以下実施例を挙げ、本発明を具体的に説明するが、本発明はこれらに限定されるものではない。尚、実施例中の部は重量部、％は重量％を示す。
【００９６】
［製造例１］
窒素導入管、温度計、攪拌装置を備えた５００ｍｌ四つ口フラスコに数平均分子量１０００のポリ（３−メチル−１，５−ペンタンアジペートジオール）を２００部、ベンゾフェノンテトラカルボン酸二無水物（以下、ＢＴＤＡと略す）３２．２部を投入し、窒素導入下で徐々に昇温し、１２０℃から１３０℃の間で２時間反応させた後、５０℃まで冷却し、つぎにイソフォロンジイソシアナート（以下、ＩＰＤＩと略す）１３．３部を加え、５０℃から６０℃に昇温し、２時間保持して反応させポリウレタン樹脂を製造した。これに、グリシジルメタクリレート２８．４部を加え、５０℃から５５℃で３時間保持して残存しているＢＴＤＡ由来のカルボキシル基と反応させ目的とするポリウレタン樹脂Ａを得た。ポリウレタン樹脂Ａは酸価がほぼ０で重量平均分子量は約２４，０００であった。ポリウレタン樹脂Ａの一般式（Ｉ）で示される構成単位の重量割合は１１％であった（ポリウレタン１分子中に、一般式（Ｉ）で示される構成単位を３つ有し、不飽和変性剤残基を６つ有する構造に対応する）。
【００９７】
［製造例２］
窒素導入管、温度計、攪拌装置を備えた５００ｍｌ四つ口フラスコに数平均分子量１０００のポリ（３−メチル−１，５−ペンタンアジペートジオール）を１００部、ＢＴＤＡ１６．１部を投入し、窒素導入下で徐々に昇温し、１２０℃から１３０℃の間で３時間反応させた後、５０℃まで冷却し、つぎにＩＰＤＩ６．６５部を加え、５０℃から６０℃に昇温し、２時間保持して反応させポリウレタン樹脂を製造した。これに、グリシジルメタクリレート７．１部を加え、５０℃から５５℃で３時間保持して、残存しているＢＴＤＡ由来のカルボキシル基の一部と反応させ目的とするポリウレタン樹脂Ｂを得た。さらに、水３０３部、トリエチルアミン５．５部を仕込み、均一に分散させて、固形分３０％のポリウレタン樹脂分散液とした。ポリウレタン樹脂Ｂは酸価が約２１（ｍｇＫＯＨ／ｇ）で、重量平均分子量は約２３，０００であった。ポリウレタン樹脂Ｂの一般式（Ｉ）で示される構成単位の重量割合は１２％であった（ポリウレタン１分子中に、一般式（Ｉ）で示される構成単位を３つ有し、不飽和変性剤残基を３つ有する構造に対応する）。
【００９８】
［製造例３］
窒素導入管、温度計、攪拌装置を備えた５００ｍｌ四つ口フラスコに数平均分子量４０００のポリ（３−メチル−１，５−ペンタンアジペートジオール）を２００部、ＢＴＤＡ８．０５部を投入し、窒素導入下で徐々に昇温し、１２０℃から１３０℃の間で２時間反応させた後、５０℃まで冷却し、つぎにＩＰＤＩ３．３部を加え、５０℃から６０℃に昇温し、２時間保持して反応させポリウレタン樹脂を製造した。これに、グリシジルメタクリレート７．１部を加え、５０℃から５５℃で３時間保持して残存しているＢＴＤＡ由来のカルボキシル基と反応させ目的とするポリウレタン樹脂Ｃを得た。ポリウレタン樹脂Ｃは酸価がほぼ０で、重量平均分子量は約７５，０００であった。ポリウレタン樹脂Ｃの一般式（Ｉ）で示される構成単位の重量割合は４％であった（ポリウレタン１分子中に、一般式（Ｉ）で示される構成単位を３つ有し、不飽和変性剤残基を３つ有する構造に対応する）。
【００９９】
［製造例４］
窒素導入管、温度計、攪拌装置を備えた５００ｍｌ四つ口フラスコに数平均分子量１０００のポリ（３−メチル−１，５−ペンタンアジペートジオール）を１００部、ＢＴＤＡ１６．１部を投入し、窒素導入下で徐々に昇温し、１２０℃から１３０℃の間で２時間反応させた後、５０℃まで冷却し、つぎにＩＰＤＩ２２．２部を加え、５０℃から６０℃に昇温し、２時間保持して反応させ両末端イソシアナートプレポリマーを製造した。これに、グリシジルメタクリレート１４．２部を加え、５０℃から５５℃で３時間保持して残存しているＢＴＤＡ由来のカルボキシル基と反応させた。さらに、水３２２部、トリエチルアミン１０．１部を仕込み、均一にした後、直ちにエチレンジアミン１．８部、抱水ヒドラジン２．０部を加え、３０分間反応させて、末端にヒドラジン残基を有するポリウレタン樹脂Ｄの固形分３４％の水溶液を得た。ポリウレタン樹脂Ｄは酸価が約２０（ｍｇＫＯＨ／ｇ）で、重量平均分子量は約２６，０００であった。ポリウレタン樹脂Ｄの一般式（Ｉ）で示される構成単位の重量割合は１１％であった（ポリウレタン１分子中に、一般式（Ｉ）で示される構成単位を３つ有し、不飽和変性剤残基を３つ有する構造に対応する）。
【０１００】
［製造例５］
窒素導入管、温度計、攪拌装置を備えた５００ｍｌ四つ口フラスコに数平均分子量１０００のポリ（３−メチル−１，５−ペンタンアジペートジオール）を９０部、ＢＴＤＡ １９．３部を投入し、１２０℃で２時間反応させ、ついでＩＰＤＩ１３．３部を仕込み、１００℃から１２０℃の間で５時間反応させ、両末端イソシアナートのポリウレタンを合成した。反応終了後１００℃まで冷却し、空気を吹き込みながら、数平均分子量４００のポリカプロラクトンジオールモノメタクリレート２４部を仕込み、１００℃から１１０℃で３時間反応させて目的とするポリウレタン樹脂Ｅを合成した。ポリウレタン樹脂Ｅは酸価が約２２（ｍｇＫＯＨ／ｇ）で、重量平均分子量は約１７，０００であった。ポリウレタン樹脂Ｅの一般式（Ｉ）で示される構成単位の重量割合は９％であった（ポリウレタン１分子中に、一般式（Ｉ）で示される構成単位を２つ有し、不飽和変性剤残基を２つ有する構造に対応する）。
【０１０１】
［製造例６］
窒素導入管、温度計、攪拌装置を備えた５００ｍｌ四つ口フラスコに数平均分子量１０００のポリ（３−メチル−１，５−ペンタンアジペートジオール）を１００部、ＢＴＤＡ１６．１部を投入し、窒素導入下で徐々に昇温し、１２０℃から１３０℃の間で２時間反応させた後、５０℃まで冷却し、つぎにＩＰＤＩ２２．２部を加え、５０℃から６０℃に昇温し、２時間保持して反応させ末端イソシアナートプレポリマーを製造した。これに、グリシジルメタクリレート１４．２部を加え、５０℃から５５℃で３時間保持して残存しているＢＴＤＡ由来のカルボキシル基と反応させた。さらに、水３２２部、トリエチルアミン１０．１部を仕込み、均一にした後、直ちにエチレンジアミン１．８部、モノエタノールアミン２．４部を加え、３０分間反応させて、固形分３４％のポリウレタン樹脂Ｆの水溶液を得た。ポリウレタン樹脂Ｆは酸価がほぼ２０（ｍｇＫＯＨ／ｇ）で、重量平均分子量は約２６，０００であった。ポリウレタン樹脂Ｆの一般式（Ｉ）で示される構成単位の重量割合は１１％であった（ポリウレタン１分子中に、一般式（Ｉ）で示される構成単位を３つ有し、不飽和変性剤残基を３つ有する構造に対応する）。
【０１０２】
［製造例７］
窒素導入管、温度計、攪拌装置を備えた５００ｍｌ四つ口フラスコに数平均分子量６０００のポリ（３−メチル−１，５−ペンタンアジペートジオール）を１８０部、ＢＴＤＡ４．８３部を投入し、窒素導入下で徐々に昇温し、１２０℃から１３０℃の間で２時間反応させた後、５０℃まで冷却し、つぎにＩＰＤＩ２．００部を加え、５０℃から６０℃に昇温し、２時間保持して反応させポリウレタン樹脂を製造した。これに、グリシジルメタクリレート４．２６部を加え、５０℃から５５℃で３時間保持して残存しているＢＴＤＡ由来のカルボキシル基と反応させ目的とするポリウレタン樹脂Ｇを得た。ポリウレタン樹脂Ｇは酸価がほぼ０で、重量平均分子量は約１００，０００であった。ポリウレタン樹脂Ｇの一般式（Ｉ）で示される構成単位の重量割合は２．５％であった（ポリウレタン１分子中に、一般式（Ｉ）で示される構成単位を３つ有し、不飽和変性剤残基を６つ有する構造に対応する）。
【０１０３】
［製造例８］
窒素導入管、温度計、攪拌装置を備えた５００ｍｌ四つ口フラスコに数平均分子量１０００のポリ（３−メチル−１，５−ペンタンアジペートジオール）を１５０部、ＩＰＤＩ１３．３部を投入し、１００℃から１２０℃の間で５時間反応させ、両末端水酸基のポリウレタンを合成した。これにＢＴＤＡ１９．３部を仕込み、１２０℃で２時間反応し、反応終了後１００℃まで冷却した。さらに、空気を吹き込みながら、数平均分子量２５００のポリカプロラクトンジオールモノメタクリレート１５０部を仕込み、１００℃から１１０℃で３時間反応させて目的とするポリウレタン樹脂Ｈを合成した。ポリウレタン樹脂Ｈは酸価が約１２（ｍｇＫＯＨ／ｇ）で、重量平均分子量は約３１，０００であった。ポリウレタン樹脂Ｈの一般式（Ｉ）で示される構成単位の重量割合は７％であった（ポリウレタン１分子中に、一般式（Ｉ）で示される構成単位を２つ有し、不飽和変性剤残基を２つ有する構造に対応する）。
【０１０４】
［実施例１〜１２］
製造例で得られたポリウレタン樹脂ＡからＦを用い、表１に示した配合処方で室温にて十分に攪拌混合し、光硬化性被覆剤又は組成物を得た。
【０１０５】
実施例１、３、５は、本発明のポリウレタン樹脂Ａ、Ｃ、Ｅをそのまま光硬化性被覆剤として使用した例である。
【０１０６】
実施例２、４、６は、本発明のポリウレタン樹脂Ｂ、Ｄ、Ｆを水に溶解し、水性化された光硬化性被覆剤としたものである。
【０１０７】
実施例７から１２は、ポリウレタン樹脂Ａ、Ｂ、Ｃを光重合開始剤として使用し、ラジカル重合性不飽和結合を有する化合物を併用した例である。そのうち、実施例１０〜１２は、更にヒドラジン化合物を配合した例である。
【０１０８】
得られた光硬化性被覆剤又は組成物について、つぎの項目の性能を評価した。実施例５、１０〜１２では硬化皮膜の耐溶剤性能を評価した。
【０１０９】
［評価方法］
１．硬化性能
実施例１〜１２で得られた光硬化性被覆剤又は組成物を紫外線をほとんど透過しない透明軟質ポリ塩化ビニルシート（大きさ２ｃｍ×２ｃｍ、厚さ１ｍｍ）上に０．３ｇ滴下し、もう一枚の透明軟質ポリ塩化ビニルシートを重ね合せ、太陽光に暴露した。透明軟質ポリ塩化ビニルシートが剥がれなくなるまでの時間でその硬化性能を評価した。
【０１１０】
◎：５分未満
○：５〜１０分
△：１０〜２０分
×：２０分以上
【０１１１】
２．水希釈性能
各光硬化性被覆剤又は組成物１０部に水１０部を撹拌しながら混合し、１６時間後の状態を観察した。
【０１１２】
○：均一な状態を保っている。
×：沈殿物もしくは結晶の析出が見られる。
【０１１３】
３．水洗浄性能
炭酸ナトリウム６部と炭酸水素ナトリウム４部を水９０部に溶解したアルカリ水を用意し、各光硬化性被覆剤又は組成物をガラス板上に膜厚が５μｍとなるように塗布した試験片を、これに３０分間浸せきし、溶解性を評価した。
【０１１４】
○：ガラス板上に被覆剤又は組成物が残らず、きれいに洗い流された。
×：ガラス板上に被覆剤又は組成物が残る。
【０１１５】
４．硬化皮膜の耐溶剤性能
各光硬化性被覆剤又は組成物を軟質ポリ塩化ビニルシート上にメアバー（０．２５ｍｍ）を用いて展色し、太陽光を２時間照射後の硬化塗膜上にメチルエチルケトンを滴下し、外観の変化で評価した。
【０１１６】
○：変化無し
△：膨潤が認められる
×：表面が溶解
【０１１７】
［比較例１〜４及び参照例］
表２に示される配合で、実施例１〜１２と同様の操作により光硬化性被覆剤又は組成物を調製し、硬化性能、水希釈性、水洗浄性を評価した。結果を表２に示す。
【０１１８】
比較例１は、分子内に含まれる一般式（Ｉ）で示される構成単位の重量割合が２．５％であるポリウレタン樹脂Ｇを使用した例である。
【０１１９】
比較例２は、数平均分子量が２，０００を超える不飽和変性剤により変性されたポリウレタン樹脂Ｈを使用した例である。
【０１２０】
比較例３、４は、従来より知られているオルトベンゾイル安息香酸、ベンゾフェノンを光重合開始剤として使用した例である。
【０１２１】
なお、実施例７で得た光硬化性組成物を用い、太陽光を照射しない条件での実験を参照例として同様な評価をした。
【０１２２】
【表１】

【０１２３】
【表２】

【０１２４】
実施例１〜１２からも明らかなように、本発明の光硬化性被覆剤又は組成物は太陽光を光源として用い、短時間の照射で十分な硬化性能を示している。さらに実施例２、４、６、１０〜１２で示したように水性の光硬化性被覆剤又は組成物とした場合でも可視光硬化性能を有していることがわかる。また、いずれの場合も水希釈性能、アルカリ水による洗浄性能を有している。
【０１２５】
一方、比較例１〜４に示したように、本発明の範囲外にある光硬化性被覆剤又は組成物や、従来より知られているオルトベンゾイル安息香酸やベンゾフェノンを用いた光硬化性組成物は十分な硬化性能を有していない。
【０１２６】
【発明の効果】
以上、実施例を挙げて説明したように、本発明の光硬化性被覆剤又は組成物は、太陽光を光源として用い、短時間の照射で十分な硬化性能を示すことから、各種の接着剤、塗料、印刷インキ等に適用できるきわめて有用な光硬化性被覆剤又は組成物である。
【０１２７】
さらに、ポリウレタン樹脂は使用するポリオール成分やポリイソシアナート成分を選択することによって、プラスチックフィルムへの接着性を向上させたり、得られる塗膜に柔軟性を与えたり、強靭性を与えたりすることが比較的容易な樹脂として知られている。こうしたポリウレタン樹脂を光重合開始剤として利用することによって、従来より高性能な接着剤や、より高性能な硬化皮膜が形成できる光硬化性被覆剤や組成物を提供することができる。
【０１２８】
さらに本発明の光硬化性被覆剤又は組成物は、水性化して用いても充分な可視光による硬化性能を有していることから、コーティング装置やインキ供給装置を水で洗浄することが可能であり、有機溶剤による毒性、環境への悪影響がなく、作業環境を改善し、作業者の健康にも配慮した光硬化性被覆剤又は組成物である。
【０１２９】
また、水性化した光硬化性被覆剤又は組成物に所定量のヒドラジン化合物を配合することによってより高性能な硬化皮膜を得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photocurable coating agent and a photocurable composition. More specifically, the present invention relates to a photocurable coating and a photocurable composition that can be cured by visible light and can be used for various coatings such as paints and printing inks, adhesives, printing resin plates, and the like.
[0002]
[Prior art]
Conventionally, adhesives, paints, printing inks, etc. using photo-curing properties have been widely used for the purpose of quick drying, improvement of working environment, energy saving, productivity and quality, etc., but these are used industrially. Most of them are UV curable. However, compositions such as ultraviolet curable adhesives, paints, and printing inks have the following problems.
[0003]
(1) Insufficient adhesion or insufficient curing when a filler or pigment is blended.
[0004]
(2) It cannot be used for bonding a base material or a film that is weak to ultraviolet rays.
[0005]
(3) It cannot be used for adhesion of materials having low UV transmittance such as soft vinyl chloride resin and polycarbonate.
[0006]
(4) The curing depth is shallow, and the thick coating film is insufficiently cured.
[0007]
(5) Toxic problems such as dilution monomers and organic solvents used to lower the viscosity of the composition are concerned, and the adverse effect of ultraviolet rays on the human body has been pointed out.
[0008]
(6) In the ultraviolet curing system, an irradiation unit equipped with a high-power metal halide lamp or the like must be provided, which causes an increase in the size and cost of the apparatus.
[0009]
Therefore, in recent years, proposals have been made regarding curable compositions in which irradiation light is visible light. However, photocurable compositions using conventionally known photopolymerization initiators such as benzophenone, orthobenzoylbenzoic acid, camphorquinone, α-benzyls, acylphosphine oxide, etc., have an energy similar to that of visible light. Sensitivity is insufficient at low light, and there is a drawback that it is impossible to impart curing performance that can withstand practical use. Further, those using a specific boron compound as a photopolymerization initiator (Japanese Patent Laid-Open No. 6-329711), those using a phenanthrenequinone and a tertiary amine as a composite photopolymerization initiator (Japanese Patent Laid-Open No. 8-291273) A novel biscoumarin compound as a sensitizer (JP-A-8-337582) has also been proposed, but it is still not sufficient.
[0010]
In addition, from the viewpoint of toxicity due to organic solvents and adverse effects on the environment, many of the UV curable compositions are conventionally solvent-free, but organic solvents must be used for cleaning coating equipment and printing presses. First, there is anxiety about workers' health. For this reason, the photocurable composition with high water detergency which was made water-based or can be easily washed with water is desired. However, there is a limit to the initiator that can be used when making it aqueous, and furthermore, there is no initiator that initiates photopolymerization with light having low energy such as visible light.
[0011]
[Problems to be solved by the invention]
An object of the present invention is to provide a photocurable coating material and a photocurable composition that can be cured by visible light, in which the above-mentioned problems of the ultraviolet curable composition are solved.
[0012]
Still another object of the present invention is to provide a photocurable coating agent and a photocurable composition that can be washed with water and have little adverse effects on the environment and the human body.
[0013]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors have found that the use of a specific compound as a photopolymerization initiator enables curing with visible light, leading to the present invention.
[0014]
That is, the present invention has (1) a structure represented by the following general formula (I) derived from a benzophenone tetracarboxylic acid compound, a urethane bond and / or a urea bond, and a number average molecular weight of 2000 or less. A polyurethane resin in which a radical-polymerizable unsaturated bond-containing group is bonded to a carboxyl group derived from a benzophenone tetracarboxylic acid compound, and the resin has a structure represented by the following general formula (I) in an amount of 3% by weight or more. Light comprising a polyurethane resin, wherein the polyurethane resin contains a structure represented by the following general formula (I) in the polyurethane resin at a ratio of 0.01% by weight or more in the total amount of the coating agent: The present invention relates to a curable coating.
[0015]
[Chemical 3]

[0016]
(Wherein R ¹ And R ² Are the same or different and each represents a hydrogen atom, a lower alkyl group or a lower alkoxy group.
[0017]
Furthermore, the present invention relates to (2) the photocurable coating agent according to item (1), wherein the polyurethane resin has a weight average molecular weight in the range of 1,000 to 200,000.
[0018]
Furthermore, the present invention relates to (3) the photocurable coating agent according to (1) or (2) above, which contains a compound having a radical polymerizable unsaturated bond in addition to the polyurethane resin.
[0019]
Further, the present invention provides (4) the photocurable composition as described in (1), (2) or (3) above, wherein the polyurethane resin is a water-soluble coating agent dissolved or dispersed in water. It relates to a coating agent.
[0020]
Furthermore, the present invention relates to (5) the photocurable coating agent according to any one of (1) to (4) above, wherein the polyurethane resin has at least one hydrazine residue in the molecule. .
[0021]
The present invention further relates to (6) an amount of hydrazine compound in which the hydrazine residue is in the range of 0.05 to 3.0 equivalents relative to the equivalent amount of the carbonyl group derived from the keto form and / or the aldehyde form in the polyurethane resin. It is related with the photocurable coating agent in any one of said (1)-(5) characterized by including.
[0022]
Furthermore, the present invention is a (7) radical having a structure represented by the following general formula (I) derived from a benzophenone tetracarboxylic acid compound, a urethane bond and / or a urea bond, and a number average molecular weight of 2000 or less. A polyurethane resin in which a group containing a polymerizable unsaturated bond is bonded to a carboxyl group derived from a benzophenone tetracarboxylic acid compound, the polyurethane having a structure represented by the following general formula (I) in an amount of 3% by weight or more A photocuring comprising the resin, wherein the polyurethane resin contains a structure represented by the following general formula (I) in the polyurethane resin at a ratio of 0.01% by weight or more in the total amount of the composition: It relates to a sex composition.
[0023]
[Formula 4]

[0024]
(Wherein R ¹ And R ² Are the same or different and each represents a hydrogen atom, a lower alkyl group or a lower alkoxy group.
[0025]
The present invention further relates to (8) the photocurable composition as described in (7) above, wherein the polyurethane resin has a weight average molecular weight in the range of 1,000 to 200,000.
[0026]
Furthermore, the present invention relates to (9) the photocurable composition as described in (7) or (8) above, which contains a compound having a radical polymerizable unsaturated bond in addition to the polyurethane resin.
[0027]
Furthermore, the present invention is (10) the photocurable composition according to (7), (8) or (9) above, wherein the polyurethane resin is a water-soluble composition dissolved or dispersed in water. Relates to the composition.
[0028]
Furthermore, the present invention relates to (11) the photocurable composition as described in any one of (7) to (10) above, wherein the polyurethane resin has at least one hydrazine residue in the molecule. .
[0029]
Furthermore, the present invention provides (12) an amount of a hydrazine compound in which the hydrazine residue is in the range of 0.05 to 3.0 equivalents relative to the equivalent of the carbonyl group derived from the keto form and / or the aldehyde form in the polyurethane resin. It is related with the photocurable composition in any one of said 7)-(11) characterized by including.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the coating agent refers to paints (including varnish) used for wood coating, vinyl chloride resin floor coating, film coating, optical fiber coating, printing ink used for lithographic printing, screen printing, metal printing, etc. This is a concept including not only various coating agents applied to the surface of an article, but also various adhesives used for primers, optical disks, plastic lenses, etc. used for the undercoat layer of paint.
[0031]
In the present invention, the composition is not only used as the coating agent, but also for applications such as a resin molded body composition such as a printing resin plate and an optical modeling material, a dry film resist, a liquid resist, a colored resist, and a semiconductor resist. It is a concept including what is used.
[0032]
Hereinafter, the present invention will be described in detail.
[0033]
The polyurethane resin used in the present invention has a structure represented by the general formula (I) derived from a benzophenone tetracarboxylic acid compound, a urethane bond and / or a urea bond, and a number average molecular weight of 2000 or less. A polyurethane resin in which a group containing a radically polymerizable unsaturated bond is bonded to a carboxyl group derived from a benzophenone tetracarboxylic acid compound, and the resin has a structure represented by the general formula (I) in an amount of 3% by weight or more. Made of polyurethane resin. In general formula (I), R ¹ , R ² Examples of the lower alkyl group represented by are methyl and ethyl, and examples of the lower alkoxy group are methoxy and ethoxy. The structure represented by the general formula (I) is usually R ¹ And R ² Are preferably hydrogen atoms.
[0034]
In the polyurethane resin of the present invention, the main chain is usually formed by the reaction of a benzophenone tetracarboxylic acid compound, a di (poly) ol component and / or di (poly) amine compound, and an organic di (poly) isocyanate compound. And a group containing a radically polymerizable unsaturated bond having a number average molecular weight of 2000 or less is bonded to at least one of the four carboxyl groups of the benzophenonetetracarboxylic acid compound that is not involved in the formation of the main chain Has been. In addition, the group containing a radically polymerizable unsaturated bond having a number average molecular weight of 2000 or less may contain a urethane bond and / or a urea bond.
[0035]
In addition, the said benzophenone tetracarboxylic acid compound means the compound in which four carbonyl groups except the central carbonyl group are carboxyl groups in the said general formula (I), and those acid anhydrides. Examples of the benzophenone tetracarboxylic acid compound include benzophenone tetracarboxylic acid, 2,2'-dimethylbenzophenone tetracarboxylic acid, 2,2'-dimethoxybenzophenone tetracarboxylic acid, and acid anhydrides thereof.
[0036]
The polyurethane resin used in the present invention can be obtained, for example, by the following method.
[0037]
(A) Di (poly) ol compound (shown by general formula (I)) obtained by esterification reaction of benzophenone tetracarboxylic acid compound and di (poly) ol (meaning diol and / or polyol, the same applies hereinafter) 1 or 2 or more), an organic di (poly) isocyanate, and if necessary, a chain extender and a reaction terminator, are reacted by a conventionally known method to obtain a polyurethane resin. A compound having both a group capable of reacting with the carboxyl group derived from the benzophenone tetracarboxylic acid compound in the resin and a radically polymerizable unsaturated group (hereinafter sometimes referred to as an unsaturated modifier for convenience) ), For example, (meth) acrylate compounds, allyl compounds, vinyls having a hydroxyl group, amino group, epoxy group, isocyanate group, etc. It is reacted with Le compounds.
[0038]
In this method, instead of or in combination with the di (poly) ol compound, an amide of the benzophenone tetracarboxylic acid compound and di (poly) amine (meaning diamine and / or polyamine, the same shall apply hereinafter). A di (poly) amine compound obtained by an oxidization or imidization reaction can be used.
[0039]
In the method, usually, the di (poly) ol compound and / or di (poly) amine compound is used in an excess amount in an equivalent ratio with respect to the organic di (poly) isocyanate, and the terminal is di (poly) ol. It becomes a compound or a di (poly) amino compound.
[0040]
(B) Organic di (poly) isocyanate with respect to the di (poly) ol compound and / or di (poly) amine compound (which contains one or more structural units represented by formula (I)) Using an excessive amount in an equivalent ratio to obtain a terminal isocyanate-containing urethane prepolymer, and reacting a part or all of the carboxyl groups derived from the benzophenone tetracarboxylic acid compound in the urethane prepolymer with the unsaturated modifier, This may be chain-extended using a chain extender, and the resulting terminal isocyanate-containing polyurethane may be reacted with a reaction terminator. In this case, various groups can be introduced at the terminal depending on the type of the reaction terminator used. For example, an alkyl group can be introduced by reacting lower alcohols, alkylamines, and dialkylamines, a hydroxyl group can be introduced by reacting alkanolamine, and an amino group can be introduced by reacting ethylenediamine or the like.
[0041]
(C) Organic di (poly) isocyanate with respect to the di (poly) ol compound and / or di (poly) amine compound (which contains one or more structural units represented by formula (I)) Is used in an equivalent amount to obtain a terminal isocyanate-containing urethane polymer, and the terminal isocyanate is reacted with an unsaturated modifier.
[0042]
(D) a benzophenone tetracarboxylic acid derivative obtained by reacting the benzophenone tetracarboxylic acid compound and the unsaturated modifier with an equivalent ratio in which a carboxyl group derived from the benzophenone tetracarboxylic acid compound remains, and both end hydroxyl groups Or a polyurethane having amino groups at both terminals (obtained by reacting di (poly) ol and / or di (poly) amine with an organic di (poly) isocyanate).
[0043]
Each component constituting the polyurethane resin of the present invention will be described more specifically.
[0044]
Examples of the di (poly) ol include (poly) alkylene glycols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, and polypropylene glycol, glycerins such as glycerin, diglycerin, and polyglycerin, and trimethylolpropane. Polyhydric alcohols such as pentaerythritol and dipentaerythritol, polyoxyalkylene di (poly) ol, polyalkylene adipate di (poly) ol, polycaprolactone di (poly) ol, polyolefin di (poly) ol, polycarbonate di ( And poly) ol.
[0045]
Examples of the di (poly) amine include alkylene di (poly) amines such as ethylene diamine, propylene diamine, dimer diamine and diethylene triamine, alicyclic diamines such as isophorone diamine and norbornene diamine, and polyoxyalkylene diamine.
[0046]
The di (poly) ol and di (poly) amine are preferably those having a number average molecular weight of 5000 or less. When the number average molecular weight is more than 5,000, it is difficult to maintain the proportion of the structural unit represented by the general formula (I) in the polyurethane resin at 3% by weight or more, and the performance as a radical polymerization initiator is decreased. Absent.
[0047]
Examples of organic di (poly) isocyanates include aromatic diisocyanates such as tolylene diisocyanate and diphenylmethane diisocyanate, araliphatic diisocyanates such as xylylene diisocyanate and tetramethylxylylene diisocyanate, Fatty substances such as cycloaliphatic diisocyanates such as isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate Group diisocyanates and their dimers, trimers and the like.
[0048]
Examples of chain extenders include low-molecular glycols such as ethylene glycol, propylene glycol, and neopentyl glycol, polyamines such as ethylenediamine, propylenediamine, isophoronediamine, dicyclohexylmethanediamine, diethylenetriamine, and triethylenediamine, and hydrazine compounds described later. It is done. Moreover, the glycol etc. which have a carboxyl group shown by general formula (II) are mentioned.
[0049]
[Chemical formula 5]

[0050]
(Wherein R ^Three Represents a hydrogen atom or a linear or branched alkyl group having 1 to 8 carbon atoms).
[0051]
Examples of the reaction terminator include lower alcohols such as methyl alcohol and ethyl alcohol, monoalkylamines such as n-propylamine and n-butylamine, and dialkylamines such as diethylamine, di-n-propylamine and di-n-butylamine. And alkanolamines such as monoethanolamine and diethanolamine, ethylenediamine, diethylenetriamine, hydrazine and the like.
[0052]
As the unsaturated modifier, those having a number average molecular weight of 2000 or less are preferable. If the number average molecular weight of the unsaturated modifier is greater than 2000, the radical polymerizability tends to decrease, making it difficult to exhibit the desired curing performance.
[0053]
Examples of the unsaturated modifier having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2- Hydroxyalkyl (meth) acrylates such as hydroxyamyl (meth) acrylate, 2-hydroxyhexyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, polyalkylene glycol mono (meth) acrylate, polycaprolactone diol Examples include mono (meth) acrylates of polyols such as mono (meth) acrylate, allyl alcohol, adducts of glycols and radical polymerizable isocyanate compounds.
[0054]
Examples of the unsaturated modifier having an amino group include allylamine.
[0055]
Examples of the unsaturated modifier having an epoxy group include glycidyl (meth) acrylate, 2,3-epoxy-2-methylpropyl (meth) acrylate, 6,7-epoxy-bicyclo [4,3,0] nonyl (meta ) (Meth) acrylates such as acrylate, vinyl ethers such as glycidyl vinyl ether and allyl glycidyl ether, and radical polymerizable epoxy compounds such as epoxy-modified polybutadiene.
[0056]
Examples of the unsaturated modifier having an isocyanate group include m-isopropenyldimethylbenzyl isocyanate and methacryloyl isocyanate.
[0057]
As a method for producing a photopolymerization initiator having at least one hydrazine residue in the molecule of the polyurethane resin, which is a preferred embodiment of the present invention, for example, a hydrazine compound is used as a reaction terminator. be able to.
[0058]
Examples of the hydrazine compound include hydrazine, alkylenedihydrazine represented by the following general formula (III), dihydrazide compounds of saturated aliphatic dibasic acid and unsaturated dibasic acid, and these hydrazine compounds as blocking agents. Examples thereof include blocked isocyanates and polyurethane resins.
[0059]
H ₂ N-NH-Y-NH-NH ₂ (III)
(In the formula, Y represents an alkylene group having 1 to 8 carbon atoms or a residue of a saturated or unsaturated dibasic acid having 1 to 10 carbon atoms).
[0060]
More specifically, examples of the alkylene dihydrazine include methylene dihydrazine, ethylene dihydrazine, propylene dihydrazine, butylene dihydrazine, and the like. Examples of the dihydrazide compound of a saturated aliphatic dibasic acid include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide and the like. Examples of the dihydrazide compound of unsaturated dibasic acid include phthalic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide and the like.
[0061]
By using a polyurethane resin having a hydrazine residue, a reaction between a human azine residue and a carbonyl group derived from a keto form and / or an aldehyde form occurs separately from the photocuring reaction, and curing is promoted to achieve higher functionality. There is an effect that a good film can be obtained. Or when using the coating agent or composition of this invention as an adhesive agent etc., if the surface of a base material has a carbonyl group derived from a keto form and / or an aldehyde form, it shows a stronger adhesive effect.
[0062]
In order to make the polyurethane resin of the present invention water-soluble or water-dispersible, the reaction components may be selected so that the acid value is 10 mgKOH / g or more, preferably 15 mgKOH / g or more. Moreover, it becomes possible to make it water-soluble or water-dispersible by selecting a compound having an ethylene oxide chain such as polyethylene glycol as the di (poly) ol component.
[0063]
The polyurethane resin of the present invention needs to contain 3% by weight or more, preferably 10% by weight or more, of the structural unit represented by the general formula (I) in the molecule. If the content of the structural unit of the general formula (I) is less than the above range, sufficient curing performance cannot be obtained.
[0064]
The weight average molecular weight of the polyurethane resin of the present invention is preferably in the range of 1,000 to 200,000, more preferably 1,000 to 100,000. If the molecular weight is less than the above range, it is somewhat difficult to produce stably. On the other hand, if the molecular weight exceeds the above range, the coating suitability may be insufficient when the resin is used alone.
[0065]
In addition, since the polyurethane resin in the present invention has both a photopolymerization initiating function and a radical polymerization function, the total amount of the photocurable coating agent or composition of the present invention can be obtained by using only one or a mixture of two or more of the polyurethane resins. Can be configured.
[0066]
Moreover, the polyurethane resin in this invention can be used together with the compound which has another radically polymerizable unsaturated bond, and can thereby improve hardening performance more.
[0067]
In the present invention, when the polyurethane resin is used in combination with a compound having a radical polymerizable unsaturated bond and used as a composition, the polyurethane resin is used as a constituent unit represented by the general formula (I) with respect to the total amount of the composition. Must be used in an amount of 0.01% by weight or more, preferably 0.05% by weight or more, and more preferably 0.1% by weight or more. If the amount of the structural unit represented by the general formula (I) is less than the above range, sufficient curing performance cannot be obtained. On the other hand, when the amount of the structural unit exceeds 30% by weight, the amount of the compound having a radically polymerizable unsaturated bond is relatively decreased, and the properties of the cured product may be deteriorated.
[0068]
Examples of the compound having a radical polymerizable unsaturated bond used as an optional component in the present invention include conventionally known vinyl ethers, compounds having an allyl group, monomers such as (meth) acrylates, vinyl esters, oligomers thereof, and the like. Those polymers can be used without particular limitation.
[0069]
In addition, when used in an aqueous photocurable coating or composition, any compound having a water-soluble or water-dispersible radical-polymerizable unsaturated bond is not particularly limited. A hydrophilic group such as a hydroxyl group, a carboxyl group, an amino group, an amide group, a sulfonic acid group, a phosphoric acid group or a polyoxyethylene chain, and a radical polymerizable group such as a (meth) acryloyl group, a vinyl group or an allyl group The compound which has these, and the monomer or oligomer which are these salt compounds can be used.
[0070]
Specific examples of the compound having a radical polymerizable unsaturated bond include the following.
[0071]
Vinyl ethers include monofunctional vinyl ethers such as 2-ethylhexyl vinyl ether, tert-amyl vinyl ether, dodecyl vinyl ether, octadecyl vinyl ether, ethylene glycol butyl vinyl ether, triethylene glycol methyl vinyl ether, diethylene glycol divinyl ether, butanediol divinyl ether, hexanediol There are polyfunctional vinyl ethers such as divinyl ether, cyclohexanedimethanol divinyl ether, ethylene glycol divinyl ether, and tetraethylene glycol divinyl ether.
[0072]
Examples of monomers having an allyl group include 2-ethylhexyl allyl ether, tert-amyl allyl ether, dodecyl allyl ether, octadecyl allyl ether, ethylene glycol butyl allyl ether, allyl ethers such as triethylene glycol methyl allyl ether, allyl alcohol, acetic acid There are monofunctional monomers such as allyl, and polyfunctional monomers such as diallyl phthalate.
[0073]
Examples of (meth) acrylates include alkyl (meth) acrylates such as methyl (meth) acrylate, ethyl (meth) acrylate, and butyl (meth) acrylate, monofunctional (meth) acrylates such as (meth) acrylamide, , 6-hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, bisphenol A di (meth) acrylate, methylenebis (meth) acrylamide, trimethylolpropane tri (meth) acrylate, glycerin tri (meth) acrylate, etc. And polyfunctional (meth) acrylates.
[0074]
Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl benzoate.
[0075]
Examples of the nitrogen-containing unsaturated monomer include N-vinyl pyrrolidone, N-vinyl carbazole, N-vinyl acetamide, vinyl pyridine and the like.
[0076]
Examples of carboxyl group-containing unsaturated monomers include (meth) acrylic acid, maleic acid, maleic acid half ester, fumaric acid, fumaric acid half ester, and salts thereof.
[0077]
Examples of the hydroxyl group-containing unsaturated monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 3-chloro-2- Examples include hydroxypropyl (meth) acrylate.
[0078]
Other monomers and oligomers include adducts of isocyanates such as butyl isocyanate and phenyl isocyanate and the above hydroxyl group-containing monomers, adducts of phosphoric acid and the above hydroxyl group-containing monomers, additions of polyhydric alcohols and alkylene oxides. Examples include products obtained by reacting (meth) acrylic acid with products, low molecular weight polymers of dienes such as butadiene and isoprene, and the like. Furthermore, there are ethylenically unsaturated group-containing polyurethane resins, ethylenically unsaturated group-containing epoxy resins, ethylenically unsaturated group-containing acrylic resins, ethylenically unsaturated group-containing silicon resins, ethylenically unsaturated group-containing melamine resins, and the like.
[0079]
When using these compounds having a radical polymerizable unsaturated bond, they can be used alone or in combination of two or more depending on the purpose, and can be used in combination with other photopolymerization initiators and sensitizers. is there.
[0080]
Moreover, in the photocurable coating agent or composition of the present invention, when a polyurethane resin and a compound having a radical polymerizable unsaturated bond are used in combination, the former is 0.5 to 95 with respect to the total amount of both. % By weight, more preferably from 1 to 90% by weight, and the latter from 5 to 99.5% by weight, more preferably from 10 to 99% by weight. Although depending on the weight ratio of the structural unit of the general formula (I) in the polyurethane resin, if the amount of the polyurethane resin used is less than the above range, the function as a photopolymerization initiator is not sufficiently exhibited, and sufficient curing performance is obtained. There is a tendency not to be. Moreover, when the said range is exceeded, there exists a tendency for the quantity of the compound which has a radically polymerizable unsaturated bond to reduce relatively, and sufficient hardening performance is not obtained.
[0081]
In the photocurable coating composition or composition of the present invention, an organic solvent may be used as the solvent, but it is preferably not used as much as possible, and when used, a water-soluble organic solvent is preferably used. Examples of the water-soluble organic solvent include methyl alcohol, ethyl alcohol, propyl alcohol, ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, methoxypropanol, N-methyl-2-pyrrolidone, and acetone.
[0082]
Another object of the present invention is to provide a photocurable coating or composition that can be diluted with water and that can be cured with visible light, with less adverse effects on the environment and the human body.
[0083]
In order to prepare such an aqueous photocurable coating agent or composition, the water-soluble or water-dispersible polyurethane resin described above is used as a polyurethane resin by dissolving or dispersing it in water as it is. be able to. Moreover, when using together the compound which has a radically polymerizable unsaturated bond, what has a water solubility or water dispersibility among the above-mentioned compounds should just be used suitably as the said compound. When the polyurethane resin and / or the compound having a radical polymerizable unsaturated bond is dissolved or dispersed in water, a surfactant or a basic substance can be used as necessary. Examples of the surfactant include polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, alkylnaphthalene sulfonic acid, polyoxyethylene alkylamine and the like. Examples of the basic substance include organic amines such as ammonia, triethylamine, triethanolamine, and morpholine, and inorganic alkalis such as sodium hydroxide and potassium hydroxide.
[0084]
Although water is used as the solvent, a small amount of the water-soluble organic solvent may be blended if necessary.
[0085]
In general, curing by a photoradical reaction is inhibited by the presence of oxygen, or when the coating film is thick, unevenness may occur in the curing, and the desired cured film may not be obtained. . In order to solve such problems, conventionally, other curing agents such as isocyanate curing agents and silane coupling agents are used in combination. However, such a curing method has a problem that heating is necessary or the mixture itself becomes unstable.
[0086]
In contrast, an aqueous photocurable coating or composition comprising a hydrazine compound which is a more preferred embodiment of the present invention comprises a hydrazine compound and a keto form in the polyurethane resin in the presence of water. And the mixture exists stably because water inhibits the reaction with carbonyl groups derived from the aldehyde form. Then, when this curable composition is formed into a coating, the reaction between the hydrazine compound and the carbonyl group derived from the keto form and aldehyde form in the polyurethane resin starts as the moisture evaporates from the coating surface. When visible light is irradiated, curing by photoradical polymerization proceeds simultaneously. As a result, it is possible to compensate for curing unevenness caused by photocuring, and to form a cured film having higher performance, for example, solvent resistance or a cured film having high surface hardness.
[0087]
The amount of the hydrazine compound used in the photocurable coating or composition is such that the hydrazine residue is 0.05 to 3.0 equivalents relative to the carbonyl group derived from the keto form and / or the aldehyde form in the polyurethane resin. A range is preferable. If the hydrazine residue is less than 0.05 equivalent, a high-performance cured film will not be formed. On the other hand, if it exceeds 3.0 equivalents, cross-linking between molecules will not be possible, and a high-performance cured film will be formed. Not. In this respect, the amount of hydrazine residue used is more preferably in the range of 0.5 to 1.5 equivalents.
[0088]
As the hydrazine compound, the hydrazine compound used in the production of the polyurethane resin having a hydrazine residue described above can be used.
[0089]
In addition to the components described above, the photocurable coating or composition of the present invention has a polymerization inhibitor such as hydroquinone, catechol, and picric acid, and other leveling agents and antifoaming agents that do not affect the curing performance. It can add suitably in the range. In addition, other conventionally known additives such as other photopolymerization initiators, sensitizers for promoting polymerization, various organic and inorganic colorants, extender pigments, and the like are appropriately added depending on the purpose within a range not affecting the curing performance. be able to. These additives are preferably used so that their total amount is about 0.1 to 20% by weight in the coating agent or composition.
[0090]
The photocurable coating agent or composition of the present invention can be obtained by uniformly mixing the components described above at room temperature using a stirrer such as a dispaper.
[0091]
The photocurable coating agent or composition of the present invention is preferably stored in a cool and dark place in a container that can block light.
[0092]
The mechanism for initiating polymerization when the polyurethane resin in the present invention is used as a photopolymerization initiator is not necessarily clear, but is excited by light energy absorbed by the carbonyl group located at the center in the structure represented by the general formula (I). It is estimated that the radical species generated at the time of extracting hydrogen from a compound having active hydrogen present in the vicinity contribute to the initiation of polymerization.
[0093]
As a curing method of the photocurable coating agent or composition of the present invention, if it is a coating agent, it is applied onto a substrate using various coating machines and then irradiated with an effective amount of visible light. Good. Moreover, when using the coating agent or composition of this invention as an adhesive agent of a transparent sheet, after apply | coating the coating agent or composition of this invention to one base material, the other base material is match | combined and a coating agent is combined. Or what is necessary is just to irradiate the amount of visible light effective in hardening a composition. Furthermore, when used for an outer wall paint of a building or the like, it can be cured by being exposed to sunlight as it is after being applied to the outer wall material.
[0094]
The light source is not particularly limited as long as it can irradiate an effective amount of visible light. For example, sunlight, halogen lamp, incandescent lamp, carbon arc, mercury vapor arc, high pressure mercury lamp, metal halide lamp, xenon lamp, A visible light laser or the like can be used. In addition, ionizing radiation can be used.
[0095]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. In addition, the part in an Example shows a weight part and% shows weight%.
[0096]
[Production Example 1]
In a 500 ml four-necked flask equipped with a nitrogen inlet tube, a thermometer, and a stirrer, 200 parts of poly (3-methyl-1,5-pentaneadipate diol) having a number average molecular weight of 1000, benzophenone tetracarboxylic dianhydride (hereinafter referred to as “the benzophenone tetracarboxylic dianhydride”) And abbreviated to BTDA), 32.2 parts were added, the temperature was gradually raised under nitrogen introduction, the reaction was carried out between 120 ° C. and 130 ° C. for 2 hours, cooled to 50 ° C., and then isophorone diisocyanate. 13.3 parts of natto (hereinafter abbreviated as IPDI) was added, the temperature was raised from 50 ° C. to 60 ° C., and the reaction was continued for 2 hours to produce a polyurethane resin. To this was added 28.4 parts of glycidyl methacrylate, and the mixture was allowed to react with the remaining BTDA-derived carboxyl groups held at 50 ° C. to 55 ° C. for 3 hours to obtain the intended polyurethane resin A. Polyurethane resin A had an acid value of approximately 0 and a weight average molecular weight of approximately 24,000. The weight ratio of the structural unit represented by the general formula (I) of the polyurethane resin A was 11% (one molecule of the polyurethane has three structural units represented by the general formula (I) and is an unsaturated modifier. Corresponding to a structure with 6 residues).
[0097]
[Production Example 2]
A 500 ml four-necked flask equipped with a nitrogen inlet tube, a thermometer, and a stirrer was charged with 100 parts of poly (3-methyl-1,5-pentaneadipatediol) having a number average molecular weight of 1000 and 16.1 parts of BTDA. The temperature was gradually raised under the introduction, the reaction was carried out between 120 ° C. and 130 ° C. for 3 hours, then cooled to 50 ° C., then 6.65 parts of IPDI was added, and the temperature was raised from 50 ° C. to 60 ° C. A polyurethane resin was produced by maintaining the reaction for a period of time. To this, 7.1 parts of glycidyl methacrylate was added and held at 50 ° C. to 55 ° C. for 3 hours to react with a part of the remaining BTDA-derived carboxyl groups to obtain the desired polyurethane resin B. Further, 303 parts of water and 5.5 parts of triethylamine were charged and uniformly dispersed to obtain a polyurethane resin dispersion having a solid content of 30%. The polyurethane resin B had an acid value of about 21 (mgKOH / g) and a weight average molecular weight of about 23,000. The weight ratio of the structural unit represented by the general formula (I) of the polyurethane resin B was 12% (one molecule of the polyurethane has three structural units represented by the general formula (I) and is an unsaturated modifier. Corresponding to a structure with three residues).
[0098]
[Production Example 3]
A 500 ml four-necked flask equipped with a nitrogen inlet tube, a thermometer, and a stirrer was charged with 200 parts of poly (3-methyl-1,5-pentaneadipatediol) having a number average molecular weight of 4000 and 8.05 parts of BTDA. The temperature was gradually raised under the introduction, and the reaction was carried out at 120 to 130 ° C. for 2 hours, then cooled to 50 ° C., then 3.3 parts of IPDI was added, and the temperature was raised from 50 ° C. to 60 ° C. A polyurethane resin was produced by maintaining the reaction for a period of time. To this, 7.1 parts of glycidyl methacrylate was added, and the mixture was held at 50 ° C. to 55 ° C. for 3 hours to react with the remaining BTDA-derived carboxyl groups to obtain the desired polyurethane resin C. Polyurethane resin C had an acid value of approximately 0 and a weight average molecular weight of approximately 75,000. The weight ratio of the structural unit represented by the general formula (I) of the polyurethane resin C was 4% (one molecule of the polyurethane has three structural units represented by the general formula (I) and is an unsaturated modifier. Corresponding to a structure with three residues).
[0099]
[Production Example 4]
A 500 ml four-necked flask equipped with a nitrogen inlet tube, a thermometer, and a stirrer was charged with 100 parts of poly (3-methyl-1,5-pentaneadipatediol) having a number average molecular weight of 1000 and 16.1 parts of BTDA. The temperature was gradually raised under the introduction, and the reaction was carried out at 120 ° C to 130 ° C for 2 hours, then cooled to 50 ° C, then 22.2 parts of IPDI was added, and the temperature was raised from 50 ° C to 60 ° C. The reaction was carried out while maintaining the time to produce a both-end isocyanate prepolymer. To this, 14.2 parts of glycidyl methacrylate was added and allowed to react with the remaining BTDA-derived carboxyl group by maintaining at 50 to 55 ° C. for 3 hours. Further, 322 parts of water and 10.1 parts of triethylamine were added and homogenized. Immediately after that, 1.8 parts of ethylenediamine and 2.0 parts of hydrazine hydrate were added and reacted for 30 minutes to give a polyurethane having a hydrazine residue at the terminal. An aqueous solution of Resin D with a solid content of 34% was obtained. Polyurethane resin D had an acid value of about 20 (mg KOH / g) and a weight average molecular weight of about 26,000. The weight proportion of the structural unit represented by the general formula (I) of the polyurethane resin D was 11% (one molecule of the polyurethane has three structural units represented by the general formula (I) and is an unsaturated modifier. Corresponding to a structure with three residues).
[0100]
[Production Example 5]
Into a 500 ml four-necked flask equipped with a nitrogen inlet tube, a thermometer, and a stirrer, 90 parts of poly (3-methyl-1,5-pentaneadipatediol) having a number average molecular weight of 1000 and 19.3 parts of BTDA were added. The reaction was carried out at 120 ° C. for 2 hours, and then 13.3 parts of IPDI was added, and the reaction was carried out at a temperature between 100 ° C. and 120 ° C. for 5 hours to synthesize both end isocyanate polyurethanes. After completion of the reaction, the reaction system was cooled to 100 ° C., and 24 parts of polycaprolactone diol monomethacrylate having a number average molecular weight of 400 was charged while blowing air, and reacted at 100 ° C. to 110 ° C. for 3 hours to synthesize the target polyurethane resin E. Polyurethane resin E had an acid value of about 22 (mgKOH / g) and a weight average molecular weight of about 17,000. The weight ratio of the structural unit represented by the general formula (I) of the polyurethane resin E was 9% (one molecule of the polyurethane has two structural units represented by the general formula (I) and is an unsaturated modifier. Corresponding to a structure with two residues).
[0101]
[Production Example 6]
A 500 ml four-necked flask equipped with a nitrogen inlet tube, a thermometer, and a stirrer was charged with 100 parts of poly (3-methyl-1,5-pentaneadipatediol) having a number average molecular weight of 1000 and 16.1 parts of BTDA. The temperature was gradually raised under the introduction, and the reaction was carried out at a temperature between 120 ° C. and 130 ° C. for 2 hours. The terminal isocyanate prepolymer was produced by maintaining the reaction for a long time. To this, 14.2 parts of glycidyl methacrylate was added and allowed to react with the remaining BTDA-derived carboxyl group by maintaining at 50 to 55 ° C. for 3 hours. Further, 322 parts of water and 10.1 parts of triethylamine were added and homogenized. Immediately after that, 1.8 parts of ethylenediamine and 2.4 parts of monoethanolamine were added and reacted for 30 minutes to obtain a polyurethane resin F having a solid content of 34%. An aqueous solution of was obtained. The polyurethane resin F had an acid value of about 20 (mgKOH / g) and a weight average molecular weight of about 26,000. The weight ratio of the structural unit represented by the general formula (I) of the polyurethane resin F was 11% (one molecule of the polyurethane has three structural units represented by the general formula (I) and is an unsaturated modifier. Corresponding to a structure with three residues).
[0102]
[Production Example 7]
A 500 ml four-necked flask equipped with a nitrogen inlet tube, a thermometer, and a stirrer was charged with 180 parts of poly (3-methyl-1,5-pentaneadipatediol) having a number average molecular weight of 6000 and 4.83 parts of BTDA, and nitrogen. The temperature was gradually raised under the introduction, and the reaction was carried out at a temperature between 120 ° C. and 130 ° C. for 2 hours. A polyurethane resin was produced by maintaining the reaction for a period of time. To this was added 4.26 parts of glycidyl methacrylate, and the mixture was held at 50 to 55 ° C. for 3 hours to react with the remaining BTDA-derived carboxyl groups to obtain the desired polyurethane resin G. The polyurethane resin G had an acid value of approximately 0 and a weight average molecular weight of approximately 100,000. The weight ratio of the structural unit represented by the general formula (I) of the polyurethane resin G was 2.5% (the polyurethane has one structural unit represented by the general formula (I) in one molecule of polyurethane and is unsaturated). Corresponding to a structure with 6 modifier residues).
[0103]
[Production Example 8]
A 500 ml four-necked flask equipped with a nitrogen inlet tube, a thermometer, and a stirrer was charged with 150 parts of poly (3-methyl-1,5-pentaneadipatediol) having a number average molecular weight of 1000 and 13.3 parts of IPDI. The reaction was carried out at 5 ° C. to 120 ° C. for 5 hours to synthesize polyurethane having both terminal hydroxyl groups. This was charged with 19.3 parts of BTDA, reacted at 120 ° C. for 2 hours, and cooled to 100 ° C. after completion of the reaction. Furthermore, while blowing air, 150 parts of polycaprolactone diol monomethacrylate having a number average molecular weight of 2500 was charged and reacted at 100 to 110 ° C. for 3 hours to synthesize the target polyurethane resin H. The polyurethane resin H had an acid value of about 12 (mgKOH / g) and a weight average molecular weight of about 31,000. The weight ratio of the structural unit represented by the general formula (I) of the polyurethane resin H was 7% (one molecule of the polyurethane has two structural units represented by the general formula (I) and is an unsaturated modifier. Corresponding to a structure with two residues).
[0104]
[Examples 1 to 12]
Using the polyurethane resins A to F obtained in the production examples, the mixture recipe shown in Table 1 was sufficiently stirred and mixed at room temperature to obtain a photocurable coating agent or composition.
[0105]
Examples 1, 3, and 5 are examples in which the polyurethane resins A, C, and E of the present invention are used as they are as a photocurable coating agent.
[0106]
Examples 2, 4, and 6 are obtained by dissolving the polyurethane resins B, D, and F of the present invention in water to obtain water-based photocurable coating agents.
[0107]
Examples 7 to 12 are examples in which polyurethane resins A, B, and C were used as photopolymerization initiators and a compound having a radical polymerizable unsaturated bond was used in combination. Among them, Examples 10 to 12 are examples in which a hydrazine compound is further blended.
[0108]
About the obtained photocurable coating material or composition, the performance of the following item was evaluated. In Examples 5 and 10 to 12, the solvent resistance performance of the cured film was evaluated.
[0109]
[Evaluation methods]
1. Curing performance
0.3 g of the photocurable coating or composition obtained in Examples 1 to 12 was dropped on a transparent soft polyvinyl chloride sheet (size 2 cm × 2 cm, thickness 1 mm) that hardly transmits ultraviolet rays. A sheet of transparent soft polyvinyl chloride sheet was overlaid and exposed to sunlight. The curing performance was evaluated by the time until the transparent soft polyvinyl chloride sheet was not peeled off.
[0110]
: Less than 5 minutes
○: 5 to 10 minutes
Δ: 10 to 20 minutes
×: 20 minutes or more
[0111]
2. Water dilution performance
10 parts of water was mixed with 10 parts of each photocurable coating agent or composition while stirring, and the state after 16 hours was observed.
[0112]
○: A uniform state is maintained.
X: Precipitation or precipitation of crystals is observed.
[0113]
3. Water washing performance
Prepare an alkaline water prepared by dissolving 6 parts of sodium carbonate and 4 parts of sodium hydrogen carbonate in 90 parts of water, and apply a test piece obtained by coating each photocurable coating agent or composition on a glass plate to a thickness of 5 μm. This was immersed for 30 minutes and the solubility was evaluated.
[0114]
○: The coating agent or composition did not remain on the glass plate and was washed away cleanly.
X: A coating agent or a composition remains on a glass plate.
[0115]
4). Solvent resistance of cured film
Each photo-curable coating agent or composition was developed on a soft polyvinyl chloride sheet using a Mere bar (0.25 mm), and methyl ethyl ketone was dropped on the cured coating film after being irradiated with sunlight for 2 hours. Evaluated by change.
[0116]
○: No change
Δ: Swelling is observed
×: Surface is dissolved
[0117]
[Comparative Examples 1 to 4 and Reference Example]
With the formulation shown in Table 2, a photocurable coating agent or composition was prepared in the same manner as in Examples 1 to 12, and the curing performance, water dilutability, and water washability were evaluated. The results are shown in Table 2.
[0118]
Comparative Example 1 is an example using a polyurethane resin G in which the weight ratio of the structural unit represented by the general formula (I) contained in the molecule is 2.5%.
[0119]
Comparative Example 2 is an example using a polyurethane resin H modified with an unsaturated modifier having a number average molecular weight exceeding 2,000.
[0120]
Comparative Examples 3 and 4 are examples using conventionally known orthobenzoylbenzoic acid and benzophenone as photopolymerization initiators.
[0121]
In addition, using the photocurable composition obtained in Example 7, the same evaluation was performed using an experiment under a condition in which sunlight was not irradiated as a reference example.
[0122]
[Table 1]

[0123]
[Table 2]

[0124]
As is clear from Examples 1 to 12, the photocurable coating agent or composition of the present invention uses sunlight as a light source, and exhibits sufficient curing performance with short-time irradiation. Further, as shown in Examples 2, 4, 6, and 10 to 12, it can be seen that even when an aqueous photocurable coating agent or composition is used, it has visible light curing performance. Moreover, in any case, it has water dilution performance and washing performance with alkaline water.
[0125]
On the other hand, as shown in Comparative Examples 1 to 4, a photocurable coating agent or composition outside the scope of the present invention, or a photocurable composition using conventionally known orthobenzoylbenzoic acid or benzophenone. Does not have sufficient curing performance.
[0126]
【The invention's effect】
As described above with reference to the examples, the photocurable coating agent or composition of the present invention uses sunlight as a light source, and exhibits sufficient curing performance with short-time irradiation. It is a very useful photo-curable coating or composition applicable to paints, printing inks and the like.
[0127]
Furthermore, polyurethane resins can improve the adhesion to plastic films, give the resulting coating film flexibility or toughness by selecting the polyol component and polyisocyanate component to be used. It is known as a relatively easy resin. By using such a polyurethane resin as a photopolymerization initiator, it is possible to provide a photocurable coating agent or composition capable of forming a higher performance adhesive or a higher performance cured film.
[0128]
Furthermore, since the photocurable coating agent or composition of the present invention has sufficient curing performance with visible light even if it is used in the form of an aqueous solution, it is possible to wash the coating apparatus and the ink supply apparatus with water. Yes, it is a photo-curable coating or composition that is free from toxicity by organic solvents and does not adversely affect the environment, improves the working environment, and considers the health of workers.
[0129]
Moreover, a higher performance cured film can be obtained by blending a predetermined amount of a hydrazine compound into an aqueous photocurable coating agent or composition.

Claims (16)

A group having a structure represented by the following general formula (I) derived from a benzophenone tetracarboxylic acid compound, a urethane bond and / or a urea bond, and a radically polymerizable unsaturated bond having a number average molecular weight of 2000 or less there a polyurethane resin which is bound to a carboxyl group derived from benzophenone tetracarboxylic acid compound, the structure represented by the following general formula (I) polyurethane resins containing 3% by weight or more in the resin is in the polyurethane resin light-curable coating agent characterized Oh Rukoto at a rate equal to or greater than 0.01% by weight structure in the coating total amount represented by the following general formula (I).

(Wherein R ¹ and R ² are the same or different and each represents a hydrogen atom, a lower alkyl group or a lower alkoxy group). The polyurethane resin has a main chain formed by a reaction of a benzophenone tetracarboxylic acid compound, a di (poly) ol component and / or a di (poly) amine compound, and an organic di (poly) isocyanate compound, and 2. The photocurable coating according to claim 1, wherein a group containing a radical polymerizable unsaturated bond having a number average molecular weight of 2000 or less is bonded to at least one of four carboxyl groups of the benzophenone tetracarboxylic acid compound. Agent. The polyurethane resin reacts with a di (poly) ol compound obtained by esterification reaction of a benzophenone tetracarboxylic acid compound and di (poly) ol with an organic di (poly) isocyanate to obtain a polyurethane resin, Polyurethane obtained by reacting a part or all of the carboxyl groups derived from the benzophenone tetracarboxylic acid compound in the polyurethane resin with an unsaturated modifier which is a compound having both a group capable of reacting with this and a radically polymerizable unsaturated group Resin (a); reacting di (poly) amine compound obtained by amidation or imidation reaction of benzophenone tetracarboxylic acid compound and di (poly) amine with organic di (poly) isocyanate to produce polyurethane resin Obtaining the benzophenone tetracarboxylic acid in the polyurethane resin A polyurethane resin (b) obtained by reacting a part or all of the carboxyl group derived from the compound with an unsaturated modifier which is a compound having both a group capable of reacting with this and a radically polymerizable unsaturated group; or A polyurethane resin is obtained by reacting a di (poly) ol compound and a di (poly) amine compound with an organic di (poly) isocyanate, and one of the carboxyl groups derived from the benzophenone tetracarboxylic acid compound in the polyurethane resin. The polyurethane resin (c) obtained by reacting part or all with an unsaturated modifier which is a compound having both a group capable of reacting with this and a radically polymerizable unsaturated group. Photocurable coating material. The photocurable coating agent according to any one of claims 1 to 3, wherein the polyurethane resin has a weight average molecular weight in the range of 1,000 to 200,000. The photocurable coating agent according to any one of claims 1 to 4, further comprising a compound having a radical polymerizable unsaturated bond in addition to the polyurethane resin. The photocurable coating agent according to any one of claims 1 to 5, wherein the polyurethane resin is a coating agent in which the polyurethane resin is dissolved or dispersed in water to make it water-based. Light-curable coating agent according to any one of claims 1 to 6, wherein the polyurethane resin is characterized by having at least one hydrazine residue in the molecule. The hydrazine compound is blended in such an amount that the hydrazine residue is in the range of 0.05 to 3.0 equivalents relative to the equivalent of the carbonyl group derived from the keto form and / or the aldehyde form in the polyurethane resin. The photocurable coating agent according to any one of claims 1 to 7 . A group having a structure represented by the following general formula (I) derived from a benzophenone tetracarboxylic acid compound, a urethane bond and / or a urea bond, and a radically polymerizable unsaturated bond having a number average molecular weight of 2000 or less there a polyurethane resin which is bound to the carboxyl groups derived from benzophenone tetracarboxylic acid compound, the structure represented by the following general formula (I) polyurethane resins containing 3% by weight or more in the resin is in the polyurethane resin formula (I) the photocurable composition structure is shown wherein the Oh Rukoto ratio to form a 0.01% by weight or more in the total amount of the composition in.

(Wherein R ¹ and R ² are the same or different and each represents a hydrogen atom, a lower alkyl group or a lower alkoxy group). The polyurethane resin has a main chain formed by a reaction of a benzophenone tetracarboxylic acid compound, a di (poly) ol component and / or a di (poly) amine compound, and an organic di (poly) isocyanate compound, and The photocurable composition according to claim 9, wherein a group containing a radical polymerizable unsaturated bond having a number average molecular weight of 2000 or less is bonded to at least one of four carboxyl groups of the benzophenone tetracarboxylic acid compound. object. The polyurethane resin reacts with a di (poly) ol compound obtained by esterification reaction of a benzophenone tetracarboxylic acid compound and di (poly) ol with an organic di (poly) isocyanate to obtain a polyurethane resin, Polyurethane obtained by reacting a part or all of the carboxyl groups derived from the benzophenone tetracarboxylic acid compound in the polyurethane resin with an unsaturated modifier which is a compound having both a group capable of reacting with this and a radically polymerizable unsaturated group Resin (a); reacting di (poly) amine compound obtained by amidation or imidation reaction of benzophenone tetracarboxylic acid compound and di (poly) amine with organic di (poly) isocyanate to produce polyurethane resin Obtaining the benzophenone tetracarboxylic acid in the polyurethane resin A polyurethane resin (b) obtained by reacting a part or all of the carboxyl group derived from the compound with an unsaturated modifier which is a compound having both a group capable of reacting with this and a radically polymerizable unsaturated group; or A polyurethane resin is obtained by reacting a di (poly) ol compound and a di (poly) amine compound with an organic di (poly) isocyanate, and one of the carboxyl groups derived from the benzophenone tetracarboxylic acid compound in the polyurethane resin. The polyurethane resin (c) obtained by reacting part or all with an unsaturated modifier which is a compound having both a group capable of reacting with this and a radically polymerizable unsaturated group. Photocurable composition. The photocurable composition according to any one of claims 9 to 11, wherein the polyurethane resin has a weight average molecular weight in the range of 1,000 to 200,000. The photocurable composition according to any one of claims 9 to 12, further comprising a compound having a radical polymerizable unsaturated bond in addition to the polyurethane resin. The photocurable composition according to any one of claims 9 to 13, wherein the polyurethane resin is a water-soluble composition dissolved or dispersed in water. The photocurable composition according to any one of claims 9 to 14 , wherein the polyurethane resin has at least one hydrazine residue in the molecule. The hydrazine compound is blended in such an amount that the hydrazine residue is in the range of 0.05 to 3.0 equivalents relative to the equivalent of the carbonyl group derived from the keto form and / or the aldehyde form in the polyurethane resin. The photocurable composition according to any one of claims 9 to 15 .