JP3934192B2

JP3934192B2 - Graft copolymer and coating composition containing the same

Info

Publication number: JP3934192B2
Application number: JP00982997A
Authority: JP
Inventors: 吉純松野; 伸茂奴間
Original assignee: Kansai Paint Co Ltd
Current assignee: Kansai Paint Co Ltd
Priority date: 1997-01-23
Filing date: 1997-01-23
Publication date: 2007-06-20
Anticipated expiration: 2017-01-23
Also published as: JPH10204128A

Description

【０００１】
【発明の属する技術分野】
本発明は、自動車用部品、建築用や補修用などの塗料やシ−リング剤に有用な湿気硬化型のグラフト共重合体及びこれを含む被覆用組成物に関する。
【０００２】
【従来技術及びその課題】
従来、産業機械、建造物、構築物、家具、自動車等の塗装や補修に際し、乾燥性、仕上り性、耐候性などの点からアクリルウレタン塗料が主に使用されている。該塗料は常温硬化型として優れた性能を有する塗膜を形成しうるものである。
しかしながらアクリルウレタン塗料は、通常、２液タイプであるため、一定の可使時間内に使用しなければならず、塗装作業性に問題があった。また該塗料は比較的低分子量のポリイソシアネ−ト化合物を硬化剤として用いるため、現場施工時にその蒸気による毒性や刺激性も問題であった。
【０００３】
これに対して、従来より１液化が可能であるイソシアネ−ト基による湿気硬化型の塗料が種々提案されている。例えば特開昭５６−１１８４０９号公報や特開昭６４−７５５７８号公報などには、イソシアネ−ト基含有共重合体を用いてなる塗料が開示されており、塗装作業性、安全衛生面での改善がなされた。
【０００４】
しかしながら、これらは、常温乾燥型塗料として特に望まれる乾燥性及び物性面で、２液タイプのアクリルウレタン塗料に匹敵するに至っていない。
【０００５】
【課題を解決するための手段】
本発明者らは、上記問題を解決すべく鋭意検討した結果、セルロースアセテートブチレートを使用してなるグラフト共重合体の幹部にイソシアネート基を導入してなるグラフト共重合体を被膜成分として用いることにより、乾燥性に優れ且つ膜物性を損なうことなくまた毒性や刺激性の問題のない１液タイプの塗料が得られることを見出し本発明に到達した。
【０００６】
すなわち本発明は、セルロースアセテートブチレート（ａ）１〜３０重量％とイソシアネート基含有モノマーを含む重合性不飽和モノマ−（ｂ）７０〜９９重量％を共重合させてなるグラフト共重合体であって、イソシアネート基を共重合体全重量の０．５〜２８．５重量％含有してなり、重量平均分子量２，０００〜１５０，０００でガラス転移温度０〜９０℃であることを特徴とするグラフト共重合体（Ｉ）、及びこれを主成分として含む被覆用組成物を提供するものである。
【０００７】
以下、本発明について詳細に説明する。
【０００８】
本発明に用いられるセルロ−スアセテ−トブチレ−ト（ａ）（以下、これを「ＣＡＢ」よ略称することがある）は、セルロ−スの部分アセチル化物をさらにブチルエステル化して得られるセルロ−ス誘導体であり、特に好適なものはアセチル基含有量が一般に１〜３０重量％、好ましくは１〜１４重量％で、ブチル基含有量が一般に１６〜６０重量％、好ましくは３５〜６０重量％であり、そしてＡＳＴＭ−Ｄ１３４３−５４Ｔ（ＦｏｒｍｕｌａＡ）に記載された粘度測定法により測定した場合の粘度が一般に０．００５〜５秒、好ましくは０．００５〜１秒の範囲に入るものである。具体的には、米国イ−ストマン・コダック社の製造にかかる製品、例えば商品名〔前者の数字の２桁目迄はブチル基含有量（重量％）を、また同じく３桁目は水酸基含有量を示し、そして後者の数字は粘度（秒）を示す〕で、ＥＡＢ−３８１−０．５、ＥＡＢ−５５１−０．２、ＥＡＢ−５５１−０．０１などが使用できる。
【０００９】
本発明に用いられる重合性不飽和モノマ−（ｂ）としては、例えば（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸プロピル、（メタ）アクリル酸ブチル、（メタ）アクリル酸２−エチルヘキシル、（メタ）アクリル酸オクチル、（メタ）アクリル酸ラウリル、（メタ）アクリル酸シクロヘキシル、（メタ）アクリル酸イソボルニル、（メタ）アクリル酸アダマンチル等の（メタ）アクリル酸のＣ１〜Ｃ２０のアルキル又は環状アルキルエステル；（メタ）アクリル酸メトキシブチル、（メタ）アクリル酸メトキシエチル、（メタ）アクリル酸エトキシブチル等の（メタ）アクリル酸のＣ２〜Ｃ８のアルコキシアルキルエステル；ヒドロキシエチル（メタ）アクリレ−ト、ヒドロキシプロピル（メタ）アクリレ−ト等の（メタ）アクリル酸のＣ２〜Ｃ８のヒドロキシアルキルエステル；市販品としてダイセル化学工業社製の製品であるプラクセルＦＡ−１（アクリル酸２−ヒドロキシエチル１モルにε−カプロラクトン１モルを付加したモノマ−）、プラクセルＦＭ−１、ＦＭ−３、ＦＭ−５（メタクリル酸２−ヒドロキシエチル１モルにε−カプロラクトンをそれぞれ１モル、３モル、５モル付加したモノマ−）、ユニオンカ−バイド社（米）製の製品であるＴＯＮＥＭ−１００（アクリル酸２−ヒドロキシエチル１モルにε−カプロラクトン２モルを付加したモノマ−）などの水酸基含有（メタ）アクリル酸エステル１モルとラクトン類１〜５モルとの付加物；ジメチルアミノエチル（メタ）アクリレ−ト、ジエチルアミノエチル（メタ）アクリレ−トなどの（メタ）アクリル酸のアミノアルキルエステル；（メタ）アクリルアミド、グリシジル（メタ）アクリレ−ト；スチレン、α−メチルスチレン、ビニルトルエン、（メタ）アクリロニトリル、（メタ）アクロレイン、ブタジエン、イソプレンなどが挙げられ、これらは所望の物性に応じて適宜使用される。
【００１０】
本発明の共重合体は、幹部にイソシアネ−ト成分を含有するものであり、該幹部にイソシアネ−ト基を導入するには、（ｉ）重合性不飽和モノマ−（ｂ）としてイソシアネ−ト基含有モノマ−を使用する、あるいは（ii）重合性不飽和モノマ−（ｂ）として上記水酸基やアミノ基などの活性水素含有重合性モノマ−を用いて本発明の共重合体に活性水素基を導入し、該活性水素基の等モル以上のポリイソシアネ−ト化合物を反応させる、等の方法を採用することができる。
【００１１】
上記重合性不飽和モノマ−（ｂ）として使用されるイソシアネ−ト基含有モノマ−としては、例えばイソシアネ−トエチル（メタ）アクリレ−ト、イソシアネ−トプロピル（メタ）アクリレ−ト、イソシアネ−トブチル（メタ）アクリレ−ト、イソシアネ−トヘキシル（メタ）アクリレ−ト、ｍ−イソプロペニル−α、α´−ジメチルベンジルイソシアネ−ト、ｍ−エチレニル−α、α´−ジメチルベンジルイソシアネ−トなどが挙げられ、さらにヒドロキシエチル（メタ）アクリレ−ト等の活性水素含有重合性モノマ−にヘキサメチレンジイソシアネ−ト等のポリイソシアネ−ト化合物を付加してなる不飽和化合物が挙げられる。
【００１２】
次いで活性水素含有重合性モノマ−を重合性不飽和モノマ−（ｂ）として用いた場合に、活性水素基と反応させるポリイソシアネ−ト化合物としては、ヘキサメチレンジイソシアネ−ト、トリメチルヘキサメチレンジイソシアネ−ト等の脂肪族ジイソシアネ−ト類、キシリレンジイソシアネ−ト、イソホロンジイソシアネ−ト等の脂環族ジイソシアネ−ト類等が挙げられる。
【００１３】
上記（ａ）及び（ｂ）成分の共重合は、溶液重合法によりラジカル重合開始剤の存在下でラジカル重合することによって行われ、（ｂ）成分が幹ポリマ−を形成し、（ａ）成分が枝ポリマ−を形成する本発明のグラフト共重合体を得ることができる。
【００１４】
ラジカル重合開始剤としては、過酸化ベンゾイル、ｔ−ブチルハイドロパ−オキサイド、クミルハイドロパ−オキサイド、クメンハイドロパ−オキサイド、ｔ−ブチルパ−オキシベンゾエ−ト、ｔ−ブチルパ−オキシ−２−エチルヘキサノエ−ト等の過酸化物開始剤や、アゾビスイソブチロニトリル、アゾビスジメチルバレロニトリル等のアゾ系開始剤が使用できる。
【００１５】
溶液重合に用いる溶媒としては、例えばベンゼン、トルエン、キシレン；酢酸ブチル、酢酸エチル、酢酸プロピル、セロソルブアセテ−ト等のエステル系；ジオキサン、エチレングリコ−ルジブチルエ−テル等のエ−テル系；メチルエチルケトン、メチルイソブチルケトン等のケトン系などの溶剤が挙げられ、これらは単独又は２種以上混合して使用できる。
【００１６】
上記（ａ）及び（ｂ）成分の使用割合は、（ａ）成分が１〜３０重量％、好ましくは５〜２０重量％で（ｂ）成分が７０〜９９重量％、好ましくは８０〜９５重量％である。該（ａ）成分が１重量％未満では（（ｂ）成分が９９重量％を越えると）、得られる塗膜の乾燥性、硬度が不十分となり、一方（ａ）成分が３０重量％を越えると（（ｂ）成分が７０重量％未満では）、得られる塗膜の耐久性が低下するので好ましくない。
【００１７】
本発明のグラフト共重合体は、幹部にイソシアネート基を共重合体全重量の０．５〜２８．５重量％、好ましくは３〜１５重量％含有してなる。該含有量が０．５重量％未満では、得られる塗膜の耐溶剤性、耐久性が低下し、乾燥性、硬度も不十分となり、一方２８．５重量％を越えると塗膜が脆くなり、かえって耐久性が低下するので好ましくない。
【００１８】
このようにして得られる本発明のグラフト共重合体（Ｉ）は、重量平均分子量が２，０００〜１５０，０００、好ましくは５，０００〜５０，０００で、ガラス転移温度が０〜９０℃、好ましくは１５〜７５℃である。重量平均分子量が２，０００未満では、得られる塗膜の乾燥性、硬度が満足に得られ難く、一方１５０，０００を越えると貯蔵性が低下し、得られる塗膜の仕上り性が満足に得られ難いので好ましくなく、またガラス転移温度が０℃未満では、得られる塗膜の乾燥性、硬度が満足に得られ難く、一方９０℃を越えると塗膜が脆くなり、かえって耐久性が低下する傾向がみられるので好ましくない。
【００１９】
本発明のグラフト共重合体（Ｉ）は、これ単独で湿気硬化により被膜を形成することができるものであり、本発明では該グラフト共重合体（Ｉ）を主成分として含む１液型の被覆用組成物をも提供するものである。
【００２０】
本発明の被覆用組成物としては、グラフト共重合体（Ｉ）に、必要に応じて種々の硬化剤や樹脂成分を配合してなるものが挙げられる。
【００２１】
該硬化剤成分としては、１液型とする点から、ポリイソシアネ−ト化合物やオキサゾリジン化合物などを配合することができる。
【００２２】
該硬化剤成分であるポリイソシアネ−ト化合物（II）としては、１分子中に少なくとも２個以上イソシアネ−ト基を含有する低分子化合物や重合体が使用でき、例えばヘキサメチレンジイソシアネ−ト、トリメチルヘキサメチレンジイソシアネ−ト等の脂肪族ジイソシアネ−ト類、キシリレンジイソシアネ−ト、イソホロンジイソシアネ−ト等の脂環族ジイソシアネ−ト類、これらジイソシアネ−トと多価アルコ−ルや低分子量ポリエステル樹脂や水との付加物、これらジイソシアネ−ト同志の重合体、さらにはイソシアヌレ−ト・ビュレット体などが挙げられ、さらにイソシアネ−ト基含有モノマ−を用いてなる重合体、特にイソシアネ−ト基含有モノマ−をスチレンや（メタ）アクリル酸エステル類等の他の重合性不飽和モノマ−と共重合して得られるイソシアネ−ト基含有共重合体などが挙げられる。
【００２３】
上記ポリイソシアネ−ト化合物（II）は、全樹脂固形分に対して０．５〜４０重量％、好ましくは１〜２０重量％の範囲で配合するのが適当である。
【００２４】
本発明組成物には、樹脂成分として、セルロ−スアセテ−トブチレ−ト（III)や、該セルロ−スアセテ−トブチレ−トとその他の重合性不飽和モノマ−を共重合してなる変性ビニル系共重合体（III'）を乾燥性向上の点から配合することができる。
【００２５】
セルロ−スアセテ−トブチレ−ト（III)は、上記グラフト共重合体（Ｉ）の構成単位となる（ａ）成分の説明で述べたものが使用でき、全樹脂固形分に対して０．５〜２０重量％の範囲で配合するのが適当である。
【００２６】
また変性ビニル系共重合体（III´）は、上記セルロースアセテートブチレート５〜７５重量％及びその他の重合性不飽和モノマー２５〜９５重量％を共重合してなるイソシアネート基を含まないグラフト共重合体である。その他の重合性不飽和モノマーとしては、前記グラフト共重合体（Ｉ）の構成単位となる重合性不飽和モノマー（ｂ）の説明で述べたモノマー（イソシアネート基含有モノマー及び活性水素含有モノマーを除く）から適宜選択して使用できる。
【００２７】
上記変性ビニル系共重合体（III'）は、全樹脂固形分に対して１〜３０重量％の範囲で配合するのが適当である。
【００２８】
また本発明組成物には、樹脂成分として、エチレン性重合性モノマ−類の共重合体、特にマクロモノマ−３〜３０重量％とその他の重合性不飽和モノマ−７０〜９７重量％を共重合させてなるグラフト共重合体（IV）を乾燥性向上の点から配合してもよい。該マクロモノマ−は、末端に重合性不飽和基を有するオリゴマ−又はポリマ−であり、従来公知の方法で製造されたものが使用でき、特にガラス転移温度が、５０℃以上で重量平均分子量が１，０００〜２５，０００であるものが好適である。市販品としては、東亜合成化学社製のＡＡ−２、ＡＡ−６、ＡＢ−２、ＡＢ−６などが挙げられる。その他の重合性不飽和モノマ−としては、前記グラフト共重合体（Ｉ）の構成単位となる重合性不飽和モノマ−（ｂ）の説明で述べたモノマ−（活性水素含有モノマ−を除く）から適宜選択して使用できる。
【００２９】
該グラフト共重合体（IV）は、全樹脂固形分に対して１〜２０重量％の範囲で配合するのが適当である。
【００３０】
さらに本発明組成物には、樹脂成分として、非水分散樹脂（Ｖ）を耐久性、乾燥性向上の点から配合してもよい。該非水分散樹脂（Ｖ）は、分散安定剤の存在下に、モノマ−は溶解するが該モノマ−から形成される重合体は実質的に溶解しない有機液体中で、該モノマ−を重合することにより得られるものであり、特に該非水分散樹脂（Ｖ）として、重量平均分子量３，０００〜１５０，０００の重合体を分散安定剤として、この存在下、前記グラフト共重合体（Ｉ）の構成単位となる重合性不飽和モノマ−（ｂ）の説明で述べたモノマ−（イソシアネ−ト基含有モノマ−及び活性水素含有モノマ−を除く）から適宜選択し重合させて得られるガラス転移温度が０〜１００℃の重合体の粒子分散液が好適である。
【００３１】
該非水分散樹脂（Ｖ）は、全樹脂固形分に対して０．５〜５０重量％、好ましくは１〜３０重量％の範囲で配合するのが適当である。
【００３２】
本発明組成物は、前記グラフト共重合体（Ｉ）を主成分とし、必要に応じて（II）〜（Ｖ）の硬化剤や樹脂成分などを配合してなるものであるが、組成物全体として樹脂固形分中に含まれるイソシアネート基が０．５〜２８．５重量％、好ましくは３．０〜１５．０重量％の範囲内となるように組成を選択することが貯蔵安定性や塗膜物性の点から好適である。
【００３３】
本発明組成物には、さらに必要に応じて顔料類、溶剤、紫外線吸収剤、硬化触媒、脱水剤などの通常の塗料用添加剤を配合することができる。
【００３４】
かくして得られる本発明組成物は希釈溶剤で塗装粘度に調整するだけで塗装可能となる１液型の塗料として使用できる。
【００３５】
本発明組成物の塗装方法としては、スプレ−塗り、ハケ塗り、ロ−ラ−塗り等の従来公知の方法が利用でき、通常、乾燥膜厚１０〜８０μｍ程度塗装される。
【００３６】
【実施例】
以下、実施例を挙げて本発明をさらに詳細に説明する。尚、文中「部」及び「％」は夫々「重量部」及び「重量％」を意味する。
【００３７】
グラフト共重合体（Ｉ）の製造
実施例１
撹拌装置、温度計、還流冷却器及び滴下ロ−トを備えた反応器に、酢酸ブチル１０４部及び「ＥＡＢ−５５１−０．０１」（イ−ストマン・コダック社製、ＣＡＢ）１０部を仕込み、窒素気流中で加熱し、１００℃まで昇温し、ＣＡＢが完全に溶解したことを確認した後、加熱還流し水分離器を通じてＣＡＢ中の水分を除いた。次いで同温度でスチレン９部、メチルメタクリレ−ト２２．５部、２−エチルヘキシルアクリレ−ト９部、ｎ−ブチルアクリレ−ト１３．５部、ｉ−ブチルメタクリレ−ト２２．５部、イソシアネ−トエチルメタクリレ−ト１３．５部及びｔ−ブチルパ−オキシベンゾエ−ト３部の混合液を３時間かけて滴下し、さらに同温度で２時間熟成し、不揮発分５０％のグラフト共重合体溶液（Ｉ−１）を得た。
【００３８】
実施例２〜４及び比較例１、２
実施例１において、ＣＡＢ溶液、モノマ−及び重合開始剤の混合液を表１に示す配合とする以外は実施例１と同様に行ないグラフト共重合体溶液（Ｉ−２）〜（Ｉ−６）を得た。得られたグラフト共重合体溶液及び共重合体の性状値を表１に示す。
【００３９】
【表１】

【００４０】
グラフト共重合体（IV）の製造
撹拌装置、温度計、還流冷却器及び滴下ロ−トを備えた反応器に、キシレン６７部を仕込み、撹拌しながら１２０℃まで昇温し、「ＡＡ−６」（東亜合成化学社製、マクロモノマ−）１５部、スチレン１０部、メチルメタクリレ−ト２０部、ｎ−ブチルメタクリレ−ト３０部、ｉ−ブチルメタクリレ−ト１５部、ｎ−ブチルアクリレ−ト１０部及びｔ−ブチルパ−オキシ２−エチルヘキサノエ−ト３部の混合液を３時間かけて滴下し、さらに同温度で２時間熟成した後、キシレン１５部を加えて希釈し不揮発分５５％のグラフト共重合体溶液（IV）を得た。
【００４１】
非水分散樹脂（Ｖ）の製造
撹拌装置、温度計、還流冷却器及び滴下ロ−トを備えた反応器に、キシレン７０部を仕込み、撹拌しながら１００℃まで昇温し、スチレン１０部、ｎ−ブチルメタクリレ−ト２５部、ｉ−ブチルメタクリレ−ト３５部、ｔ−ブチルメタクリレ−ト１５部、２−エチルヘキシルメタクリレ−ト１５部及び２，２´−アゾビスイソブチロニトリル１．０部の混合液を３時間かけて滴下し、さらに同温度で２時間熟成した後、キシレン３０部を加えて希釈し不揮発分５０％、粘度Ｖの分散安定剤共重合体溶液を得た。該共重合体の重量平均分子量は４５，０００、ガラス転移温度は４５℃であった。
【００４２】
得られた分散安定剤共重合体溶液１３３部及びヘプタン８５部を反応器に仕込み加熱還流させ、スチレン５部、メチルメタクリレ−ト２３部、アクリロニトリル６部、メチルアクリレ−ト６６部及び２，２´−アゾビスイソブチロニトリル１．５部の混合液を３時間滴下し、滴下後２時間熟成を行って不揮発分５２％、粘度ＥＦ、重合体粒子の粒径０．３μｍの乳白色の安定な重合体分散液を得た。
１液型クリヤ−塗料の作成
実施例５〜１４及び比較例３〜５
上記の通り得られたグラフト共重合体溶液（Ｉ−１）〜（Ｉ−６）を用いて、表２に示す配合で他成分を加えて混合撹拌し、１液型クリヤ−塗料を作成した。
次いで各クリヤ−塗料をトルエン／キシレン／酢酸エチル／酢酸ブチル＝５０／２０／１０／２０の組成のシンナ−にて１３〜１４秒（フォ−ドカップ＃４／２５℃）にて粘調し室温（２０℃）にて、市販ラッカ−プライマ−〜ラッカ−プライマ−サ−フェ−サ−〜メタリックベ−スが順次塗装されてなる工程板上に、乾燥膜厚４０μｍとなるようにスプレ−塗装を行った後、塗膜性能試験を行った。結果を表２に合わせて示す。
【００４３】
【表２】

【００４４】
尚、表２中の（注１）〜（注４）及び試験方法は下記の通りである。
【００４５】
（注１）ポリイソシアネ−ト化合物：「Ｎ−３５００」、住友バイエルウレタン社製、ヘキサメチレンジイソシアネ−トのイソシアヌレ−ト型、不揮発分１００％、ＮＣＯ基含有量２１．６％
（注２）オキサゾリジン化合物：「ＩｎｃｏｚｏｌＬＶ」、インダストリアルコポリマ−社製、純度９９％
（注３）硬化触媒Ａ：ジブチルスズジラウレ−ト
（注４）硬化触媒Ｂ：リン酸ジイソプロピルエステル
（１）乾燥性
２０℃で塗装後、塗板を水平に２０分間保った後、温度２０℃、湿度７５％ＲＨの恒温恒湿室内に静置し、塗膜表面にガ−ゼを８枚重ねたものを載せ、その上に接触面積１２．５６cm²である２００ｇの重りを載せ，ガ−ゼ跡が全くつかなくなるまでの静置時間（秒）を測定した。
【００４６】
（２）塗膜硬度
２０℃で塗装後、塗板を水平に２０分間保った後、温度２０℃、湿度７５％ＲＨの恒温恒湿室内に１日、７日間静置し、塗膜のツーコン硬度をAmerican Chain&Cable Company製ツーコン硬度計を用いて２０℃条件下で測定した。数値が大きいほど硬質である。
【００４７】
（３）仕上り外観
２０℃で塗装後、塗板を水平に２０分間保った後、温度２０℃、湿度７５％ＲＨの恒温恒湿室内に１日静置した塗板の塗膜の平滑性、肉持感と透明性を目視判定した。
【００４８】
○：良好
△：やや悪い
×：不良
（４）促進耐候性
２０℃で塗装後、塗板を水平に２０分間保った後、温度２０℃、湿度７５％ＲＨの恒温恒湿室内に７日間放置した塗板をサンシャインウェザオメ−タ−にて１０００時間試験した後の塗面の変化の有無を確認した。
【００４９】
○：塗面にほとんど変化がない
×：塗面に水跡が認められ光沢低下が大きい
（５）貯蔵安定性
塗料不揮発分４５％の各塗料を４０℃で６ケ月間密封保存したときの粘度の変化を評価した。
【００５０】
○：粘度の変化がほとんどない
△：多少増粘している
×：著しい増粘、あるいはゲル化を起こしている
【００５１】
【発明の効果】
本発明によれば、セルロースアセテートブチレートを使用してなるグラフト共重合体の幹部にイソシアネート基を導入してなるグラフト共重合体が得られ、これを被膜成分として用いることにより、乾燥性に優れ且つ膜物性を損なうことなくまた毒性や刺激性の問題のない１液タイプの塗料が得られる。本発明組成物は、特に自動車用部品、建築用や補修用などの塗料やシ−リング剤に有用である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a moisture-curable graft copolymer useful for automobile parts, paints and sealing agents for construction and repair, and a coating composition containing the same.
[0002]
[Prior art and its problems]
Conventionally, acrylic urethane paints are mainly used from the viewpoints of drying, finishing, weather resistance, and the like when painting and repairing industrial machines, buildings, structures, furniture, automobiles, and the like. The coating material can form a coating film having excellent performance as a room temperature curing type.
However, since the acrylic urethane paint is usually a two-component type, it has to be used within a certain pot life and there is a problem in the workability of painting. In addition, since the paint uses a polyisocyanate compound having a relatively low molecular weight as a curing agent, the toxicity and irritation caused by the vapor at the time of on-site construction are also problems.
[0003]
On the other hand, various moisture-curable coatings based on isocyanate groups that can be made into one liquid have been proposed. For example, Japanese Patent Application Laid-Open No. 56-118409 and Japanese Patent Application Laid-Open No. 64-75578 disclose a paint using an isocyanate group-containing copolymer. Improvements were made.
[0004]
However, they are not comparable to the two-component type acrylic urethane paints in terms of dryness and physical properties that are particularly desired as room temperature dry paints.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors use a graft copolymer obtained by introducing an isocyanate group into the trunk of a graft copolymer using cellulose acetate butyrate as a coating component. Thus, the present inventors have found that a one-component type paint having excellent drying properties and without damaging film properties and having no problems of toxicity and irritation can be obtained.
[0006]
That is, the present invention is a graft copolymer obtained by copolymerizing 1 to 30% by weight of cellulose acetate butyrate (a) and 70 to 99% by weight of a polymerizable unsaturated monomer (b) containing an isocyanate group-containing monomer. The isocyanate group contains 0.5 to 28.5% by weight of the total weight of the copolymer, and has a weight average molecular weight of 2,000 to 150,000 and a glass transition temperature of 0 to 90 ° C. A graft copolymer (I) and a coating composition containing this as a main component are provided.
[0007]
Hereinafter, the present invention will be described in detail.
[0008]
Cellulose acetate butyrate (a) (hereinafter sometimes abbreviated as “CAB”) used in the present invention is a cellulose obtained by further butyl esterifying a partially acetylated product of cellulose. Derivatives, particularly preferred are those having an acetyl group content of generally 1 to 30% by weight, preferably 1 to 14% by weight, and a butyl group content of generally 16 to 60% by weight, preferably 35 to 60% by weight. Yes, and the viscosity as measured by the viscosity measurement method described in ASTM-D1343-54T (Formula A) is generally in the range of 0.005 to 5 seconds, preferably 0.005 to 1 second. Specifically, products manufactured by Eastman Kodak Company in the United States, such as trade names (the butyl group content (% by weight) up to the second digit of the former number, and the hydroxyl content in the third digit) EAB-381-0.5, EAB-551-0.2, EAB-551-0.01, etc. can be used.
[0009]
Examples of the polymerizable unsaturated monomer (b) used in the present invention include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic. C1-C20 of (meth) acrylic acid such as 2-ethylhexyl acid, octyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, and adamantyl (meth) acrylate C2-C8 alkoxyalkyl esters of (meth) acrylic acid such as methoxybutyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxybutyl (meth) acrylate; hydroxyethyl (meth) ) Acrylate, hydroxypropyl (meth) acrylate C2-C8 hydroxyalkyl ester of (meth) acrylic acid such as Placel FA-1 (product of Daicel Chemical Industries, Ltd., 1 mol of ε-caprolactone was added to 1 mol of 2-hydroxyethyl acrylate) Monomer), Plaxel FM-1, FM-3, FM-5 (monomers obtained by adding 1 mol, 3 mol and 5 mol of ε-caprolactone to 1 mol of 2-hydroxyethyl methacrylate, respectively), Union Carbide ( 1 mol of hydroxyl group-containing (meth) acrylic acid ester and 1-5 mol of lactones such as TONEM-100 (a monomer obtained by adding 2 mol of ε-caprolactone to 1 mol of 2-hydroxyethyl acrylate). Adducts with dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate (Meth) acrylic acid such as aminoalkyl ester; (meth) acrylamide, glycidyl (meth) acrylate; styrene, α-methylstyrene, vinyltoluene, (meth) acrylonitrile, (meth) acrolein, butadiene, isoprene, etc. These are appropriately used depending on the desired physical properties.
[0010]
The copolymer of the present invention contains an isocyanate component in the trunk, and in order to introduce an isocyanate group into the trunk, (i) an isocyanate as a polymerizable unsaturated monomer (b) A group-containing monomer, or (ii) a polymerizable unsaturated monomer (b) using an active hydrogen-containing polymerizable monomer such as a hydroxyl group or an amino group as described above to form an active hydrogen group in the copolymer of the present invention. It is possible to adopt a method such as introducing and reacting an equimolar or more polyisocyanate compound of the active hydrogen group.
[0011]
Examples of the isocyanate group-containing monomer used as the polymerizable unsaturated monomer (b) include isocyanatoethyl (meth) acrylate, isocyanatopropyl (meth) acrylate, isocyanatobutyl (meta). ) Acrylate, isocyanatohexyl (meth) acrylate, m-isopropenyl-α, α'-dimethylbenzyl isocyanate, m-ethylenyl-α, α'-dimethylbenzyl isocyanate and the like. And unsaturated compounds obtained by adding a polyisocyanate compound such as hexamethylene diisocyanate to an active hydrogen-containing polymerizable monomer such as hydroxyethyl (meth) acrylate.
[0012]
Next, when the active hydrogen-containing polymerizable monomer is used as the polymerizable unsaturated monomer (b), the polyisocyanate compound to be reacted with the active hydrogen group is hexamethylene diisocyanate or trimethylhexamethylene diisocyanate. Examples thereof include aliphatic diisocyanates such as neat, alicyclic diisocyanates such as xylylene diisocyanate and isophorone diisocyanate.
[0013]
The copolymerization of the components (a) and (b) is carried out by radical polymerization in the presence of a radical polymerization initiator by a solution polymerization method, the component (b) forms a trunk polymer, and the component (a) Can provide the graft copolymer of the present invention in which a branched polymer is formed.
[0014]
As radical polymerization initiators, benzoyl peroxide, t-butyl hydroperoxide, cumyl hydroperoxide, cumene hydroperoxide, t-butyl peroxybenzoate, t-butyl peroxy-2-ethylhexanoate And peroxide initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile.
[0015]
Examples of the solvent used for the solution polymerization include benzene, toluene, xylene; ester systems such as butyl acetate, ethyl acetate, propyl acetate, and cellosolve acetate; ether systems such as dioxane and ethylene glycol dibutyl ether; methyl ethyl ketone, Examples thereof include ketone solvents such as methyl isobutyl ketone, and these can be used alone or in combination of two or more.
[0016]
The proportion of the components (a) and (b) used is such that the component (a) is 1 to 30% by weight, preferably 5 to 20% by weight and the component (b) is 70 to 99% by weight, preferably 80 to 95% by weight. %. When the component (a) is less than 1% by weight (when the component (b) exceeds 99% by weight), the resulting coating film has insufficient dryness and hardness, while the component (a) exceeds 30% by weight. (If the component (b) is less than 70% by weight), the durability of the resulting coating film is lowered, which is not preferable.
[0017]
The graft copolymer of the present invention comprises 0.5 to 28.5% by weight, preferably 3 to 15% by weight, based on the total weight of the copolymer of isocyanate groups in the trunk. When the content is less than 0.5% by weight, the solvent resistance and durability of the resulting coating film are lowered, and the drying property and hardness are insufficient. On the other hand, when the content exceeds 28.5% by weight, the coating film becomes brittle. On the contrary, it is not preferable because the durability is lowered.
[0018]
The graft copolymer (I) of the present invention thus obtained has a weight average molecular weight of 2,000 to 150,000, preferably 5,000 to 50,000, and a glass transition temperature of 0 to 90 ° C. Preferably it is 15-75 degreeC. If the weight average molecular weight is less than 2,000, it is difficult to satisfactorily obtain the drying property and hardness of the resulting coating film. When the glass transition temperature is less than 0 ° C., it is difficult to satisfactorily obtain the drying property and hardness of the coating film. On the other hand, when the glass transition temperature exceeds 90 ° C., the coating film becomes brittle and the durability is lowered. Since a tendency is seen, it is not preferable.
[0019]
The graft copolymer (I) of the present invention can form a film by moisture curing alone. In the present invention, the graft copolymer (I) is a one-pack type coating containing the graft copolymer (I) as a main component. The composition for use is also provided.
[0020]
Examples of the coating composition of the present invention include those obtained by blending the graft copolymer (I) with various curing agents and resin components as necessary.
[0021]
As this hardening | curing agent component, a polyisocyanate compound, an oxazolidine compound, etc. can be mix | blended from the point made into 1 liquid type.
[0022]
As the polyisocyanate compound (II) which is the curing agent component, a low molecular compound or a polymer containing at least two isocyanate groups in one molecule can be used. For example, hexamethylene diisocyanate, Aliphatic diisocyanates such as trimethylhexamethylene diisocyanate, alicyclic diisocyanates such as xylylene diisocyanate and isophorone diisocyanate, these diisocyanates and polyhydric alcohols And low molecular weight polyester resins, adducts with water, polymers of these diisocyanates, and isocyanurate burettes, and polymers using isocyanate group-containing monomers, particularly Copolymerization of isocyanate group-containing monomers with other polymerizable unsaturated monomers such as styrene and (meth) acrylates Obtained by isocyanate - such as preparative group-containing copolymer.
[0023]
The polyisocyanate compound (II) is blended in an amount of 0.5 to 40% by weight, preferably 1 to 20% by weight, based on the total resin solid content.
[0024]
In the composition of the present invention, as a resin component, cellulose acetate butyrate (III), or a modified vinyl copolymer obtained by copolymerizing cellulose acetate butyrate and other polymerizable unsaturated monomer is used. Polymer (III ') can be mix | blended from the point of a drying improvement.
[0025]
As the cellulose acetate butyrate (III), those described in the explanation of the component (a) which is a constituent unit of the graft copolymer (I) can be used, and 0.5 to It is appropriate to blend in the range of 20% by weight.
[0026]
Further, the modified vinyl copolymer (III ′) is a graft copolymer containing no isocyanate group formed by copolymerizing 5 to 75% by weight of the above cellulose acetate butyrate and 25 to 95% by weight of other polymerizable unsaturated monomers. It is a coalescence. As other polymerizable unsaturated monomers, the monomers (excluding isocyanate group-containing monomers and active hydrogen-containing monomers) described in the description of the polymerizable unsaturated monomer (b) which is a constituent unit of the graft copolymer (I) Can be appropriately selected and used.
[0027]
The modified vinyl copolymer (III ′) is suitably blended in the range of 1 to 30% by weight based on the total resin solid content.
[0028]
In the composition of the present invention, a copolymer of an ethylenically polymerizable monomer, particularly a macromonomer of 3 to 30% by weight, and another polymerizable unsaturated monomer of 70 to 97% by weight is copolymerized as a resin component. The graft copolymer (IV) may be added from the viewpoint of improving the drying property. The macromonomer is an oligomer or polymer having a polymerizable unsaturated group at the terminal, and those produced by a conventionally known method can be used. In particular, the glass transition temperature is 50 ° C. or higher and the weight average molecular weight is 1. 5,000 to 25,000 are preferred. Examples of commercially available products include AA-2, AA-6, AB-2, AB-6 manufactured by Toa Gosei Chemical Co., Ltd. Examples of other polymerizable unsaturated monomers include the monomers described in the description of the polymerizable unsaturated monomer (b), which is a constituent unit of the graft copolymer (I) (excluding monomers containing active hydrogen). It can be appropriately selected and used.
[0029]
The graft copolymer (IV) is suitably blended in the range of 1 to 20% by weight based on the total resin solid content.
[0030]
Furthermore, you may mix | blend non-aqueous dispersion resin (V) with this invention composition from the point of durability and a drying improvement as a resin component. In the presence of a dispersion stabilizer, the non-aqueous dispersion resin (V) polymerizes the monomer in an organic liquid that dissolves the monomer but does not substantially dissolve the polymer formed from the monomer. In particular, as the non-aqueous dispersion resin (V), a polymer having a weight average molecular weight of 3,000 to 150,000 is used as a dispersion stabilizer, and the composition of the graft copolymer (I) is present in this presence. The glass transition temperature obtained by appropriately selecting from the monomers described in the description of the polymerizable unsaturated monomer (b) (excluding the isocyanate group-containing monomer and active hydrogen-containing monomer) for polymerization is 0. A polymer particle dispersion of ˜100 ° C. is preferred.
[0031]
The non-aqueous dispersion resin (V) is suitably blended in the range of 0.5 to 50% by weight, preferably 1 to 30% by weight, based on the total resin solid content.
[0032]
The composition of the present invention comprises the graft copolymer (I) as a main component and, if necessary, a curing agent or a resin component (II) to (V) is blended, but the entire composition The composition should be selected so that the isocyanate group contained in the resin solid content is in the range of 0.5 to 28.5% by weight, preferably 3.0 to 15.0% by weight. It is preferable from the viewpoint of film properties.
[0033]
The composition of the present invention may further contain usual paint additives such as pigments, solvents, ultraviolet absorbers, curing catalysts, and dehydrating agents, if necessary.
[0034]
The composition of the present invention thus obtained can be used as a one-pack type paint that can be applied only by adjusting the coating viscosity with a diluent solvent.
[0035]
As a coating method of the composition of the present invention, conventionally known methods such as spray coating, brush coating, roller coating and the like can be used, and usually a dry film thickness of about 10 to 80 μm is applied.
[0036]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. In the text, “part” and “%” mean “part by weight” and “% by weight”, respectively.
[0037]
Production of graft copolymer (I) Example 1
A reactor equipped with a stirrer, a thermometer, a reflux condenser and a dropping funnel was charged with 104 parts of butyl acetate and 10 parts of “EAB-551-0.01” (manufactured by Eastman Kodak Company, CAB). After heating in a nitrogen stream and raising the temperature to 100 ° C. and confirming that the CAB was completely dissolved, the mixture was heated to reflux and water in the CAB was removed through a water separator. Next, at the same temperature, 9 parts of styrene, 22.5 parts of methyl methacrylate, 9 parts of 2-ethylhexyl acrylate, 13.5 parts of n-butyl acrylate, 22.5 parts of i-butyl methacrylate, A mixed solution of 13.5 parts of isocyanatoethyl methacrylate and 3 parts of t-butyl peroxybenzoate was added dropwise over 3 hours, followed by aging at the same temperature for 2 hours, and graft copolymer weight of 50% non-volatile content. A combined solution (I-1) was obtained.
[0038]
Examples 2 to 4 and Comparative Examples 1 and 2
In Example 1, the graft copolymer solutions (I-2) to (I-6) were carried out in the same manner as in Example 1 except that the mixture of the CAB solution, the monomer and the polymerization initiator was blended as shown in Table 1. Got. Table 1 shows property values of the obtained graft copolymer solution and the copolymer.
[0039]
[Table 1]

[0040]
Production of graft copolymer (IV) A reactor equipped with a stirrer, thermometer, reflux condenser and dropping funnel was charged with 67 parts of xylene and heated to 120 ° C. while stirring. 15 parts (manufactured by Toagosei Chemical Co., Ltd., macromonomer), 10 parts of styrene, 20 parts of methyl methacrylate, 30 parts of n-butyl methacrylate, 15 parts of i-butyl methacrylate, n-butyl acrylate A mixture of 10 parts of tert-butyl and 3 parts of t-butyl peroxy 2-ethylhexanoate was added dropwise over 3 hours, and the mixture was further aged for 2 hours at the same temperature. % Of the graft copolymer solution (IV) was obtained.
[0041]
Production of non-aqueous dispersion resin (V) A reactor equipped with a stirrer, thermometer, reflux condenser and dropping funnel was charged with 70 parts of xylene, heated to 100 ° C. with stirring, 10 parts of styrene, 25 parts of n-butyl methacrylate, 35 parts of i-butyl methacrylate, 15 parts of t-butyl methacrylate, 15 parts of 2-ethylhexyl methacrylate and 2,2'-azobisisobutyro A mixture of 1.0 part of nitrile was added dropwise over 3 hours and aged at the same temperature for 2 hours, and then diluted by adding 30 parts of xylene to obtain a dispersion stabilizer copolymer solution having a nonvolatile content of 50% and a viscosity of V. Obtained. The copolymer had a weight average molecular weight of 45,000 and a glass transition temperature of 45 ° C.
[0042]
133 parts of the obtained dispersion stabilizer copolymer solution and 85 parts of heptane were charged into a reactor and heated to reflux, and 5 parts of styrene, 23 parts of methyl methacrylate, 6 parts of acrylonitrile, 66 parts of methyl acrylate and 2,2 A mixed solution of 1.5 parts of ′ -azobisisobutyronitrile was dropped for 3 hours, and after ripening, aging was performed for 2 hours to stabilize milky white with non-volatile content of 52%, viscosity EF, and polymer particle size of 0.3 μm. Obtained a polymer dispersion.
Preparation of one-component clear paint Examples 5-14 and Comparative Examples 3-5
Using the graft copolymer solutions (I-1) to (I-6) obtained as described above, other components were added in the formulation shown in Table 2 and mixed and stirred to prepare a one-pack type clear paint. .
Next, each clear paint was adjusted to a viscosity of 13-14 seconds (forward cup # 4/25 ° C.) with a thinner of toluene / xylene / ethyl acetate / butyl acetate = 50/20/10/20 at room temperature. At (20 ° C.), spray coating is performed so that a dry film thickness of 40 μm is obtained on a process board in which a commercially available lacquer primer, lacquer primer primer surfacer, metallic base is coated. Then, a coating film performance test was conducted. The results are shown in Table 2.
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[Table 2]

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In Table 2, (Note 1) to (Note 4) and test methods are as follows.
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(Note 1) Polyisocyanate compound: “N-3500”, manufactured by Sumitomo Bayer Urethane Co., Ltd., isocyanurate type of hexamethylene diisocyanate, non-volatile content 100%, NCO group content 21.6%
(Note 2) Oxazolidine compound: “Incozol LV”, manufactured by Industrial Co., Ltd., purity 99%
(Note 3) Curing catalyst A: Dibutyltin dilaurate (Note 4) Curing catalyst B: Phosphoric acid diisopropyl ester (1) After coating at 20 ° C. dryness, the coated plate is kept horizontally for 20 minutes, and then at a temperature of 20 ° C. Place in a constant temperature and humidity room with a humidity of 75% RH, place 8 sheets of gauze on the surface of the coating, and place a 200 g weight with a contact area of 12.56 cm ² on it. The standing time (seconds) until no trace was made was measured.
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(2) After coating at a coating film hardness of 20 ° C., the coated plate is kept horizontally for 20 minutes and then left in a constant temperature and humidity chamber at a temperature of 20 ° C. and a humidity of 75% RH for 1 day for 7 days. Was measured at 20 ° C. using a two-cone hardness meter manufactured by American Chain & Cable Company. The larger the value, the harder.
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(3) Finished appearance After coating at 20 ° C., the coated plate is kept horizontally for 20 minutes, and then the coated plate is smoothed and preserved for one day in a constant temperature and humidity chamber at a temperature of 20 ° C. and a humidity of 75% RH. The feeling and transparency were judged visually.
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○: Good △: Slightly bad ×: Poor (4) Accelerated weather resistance After painting at 20 ° C., the coated plate was kept horizontally for 20 minutes and then left in a constant temperature and humidity room at 20 ° C. and humidity 75% RH for 7 days. After the coated plate was tested with a sunshine weatherometer for 1000 hours, the presence or absence of changes in the coated surface was confirmed.
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○: Almost no change on the coating surface ×: Water marks are observed on the coating surface and gloss reduction is large (5) Storage stable paint Viscosity when each paint having a non-volatile content of 45% is sealed and stored at 40 ° C. for 6 months Was evaluated for changes.
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○: almost no change in viscosity △: slightly thickened ×: markedly thickened or gelled [0051]
【The invention's effect】
According to the present invention, a graft copolymer obtained by introducing an isocyanate group into the trunk of a graft copolymer using cellulose acetate butyrate is obtained, and by using this as a film component, it has excellent drying properties. In addition, it is possible to obtain a one-pack type coating material that does not impair film properties and that is free from toxicity and irritation problems. The composition of the present invention is particularly useful for paints and sealing agents for automobile parts, construction and repair.

Claims

A graft copolymer comprising by copolymerizing 70 to 99 wt% polymerizable unsaturated monomer (b) containing cellulose acetate butyrate (a) 1 to 30 wt% and an isocyanate group-containing monomer, co isocyanate groups A graft copolymer comprising 0.5 to 28.5% by weight of the total weight of the polymer, having a weight average molecular weight of 2,000 to 150,000 and a glass transition temperature of 0 to 90 ° C.

A graft copolymer comprising by copolymerizing 70 to 99 wt% polymerizable unsaturated monomer (b) containing cellulose acetate butyrate (a) 1 to 30 wt% and an isocyanate group-containing monomer, co isocyanate groups The main component is a graft copolymer (I) containing 0.5 to 28.5% by weight of the total weight of the polymer and having a weight average molecular weight of 2,000 to 150,000 and a glass transition temperature of 0 to 90 ° C. A coating composition comprising.

The coating composition according to claim 2, wherein the polyisocyanate compound (II) is blended in an amount of 0.5 to 40% by weight based on the total resin solid content.

The coating composition according to claim 3, wherein the polyisocyanate compound (II) is a low molecular compound containing at least two isocyanate groups in one molecule.

4. The coating composition according to claim 3, wherein the polyisocyanate compound (II) is a polymer using an isocyanate group-containing monomer.

The coating composition according to any one of claims 2 to 5 , wherein cellulose acetate butyrate (III) is blended in an amount of 0.5 to 20% by weight based on the total resin solid content.

Modified vinyl-based copolymer (III ′) containing no isocyanate groups by copolymerizing 5 to 75% by weight of cellulose acetate butyrate and 25 to 95% by weight of other polymerizable unsaturated monomers is added to the total resin solid content. The coating composition according to any one of claims 2 to 6 , wherein the coating composition is blended in an amount of 1 to 30% by weight.

Graft copolymer (IV) obtained by copolymerizing 3 to 30% by weight of macromonomer and 70 to 97% by weight of other polymerizable unsaturated monomer is in the range of 1 to 20% by weight based on the total resin solid content. The coating composition according to any one of claims 2 to 7 , wherein the coating composition is blended as described above.

The coating composition according to any one of claims 2 to 8 , wherein the non-aqueous dispersion resin (V) is blended in an amount of 0.5 to 50% by weight based on the total resin solid content.

A glass transition obtained by polymerizing a polymerizable unsaturated monomer in a non-aqueous solvent in the presence of a non-aqueous dispersion resin (V) using a polymer having a weight average molecular weight of 3,000 to 150,000 as a dispersion stabilizer. The coating composition according to claim 9, which is a particle dispersion of a polymer having a temperature of 0 to 100 ° C.