JP3545439B2 - Method for producing ultraviolet-curable coating material and abrasion-resistant coating material composition using the same - Google Patents

Description

（式中、ＸはＣＨ₂ ＝ＣＨ−ＣＯＯ−基、ＣＨ₂ ＝Ｃ（ＣＨ₃ ）−ＣＯＯ−基、又はＣＨ₂ ＝ＣＨ−基、Ｒ₁ は炭素数１〜８のアルキレン基、Ｒ₂ ，Ｒ₃ は炭素数１〜８のアルキル基、ａは１〜３の正の整数、ｂは０〜２の正の整数、ａ＋ｂは１〜３の整数を表わす。）
で示される単量体の加水分解物（固形分）６０〜１０重量％（合計１００重量％）とを極性溶媒の存在下に、脱水量が理論値の３０〜８０重量％となった時点で極性溶媒を非極性溶媒に置換し、さらにこの非極性溶媒中、固形分３０〜９０重量％の存在状態下で、縮合反応させて得られる紫外線硬化性被覆材に関する。
また、本発明は、（Ａ）上記紫外線硬化性被覆材（固形分）５〜５０重量部、
（Ｂ）１分子中に２個以上の（メタ）アクリロイルオキシ基を有する多官能性単量体又は単量体混合物９５〜５０重量部、及び
（Ｃ）光重合開始剤０．０１〜５重量部（上記（Ａ）成分と上記（Ｂ）成分との合計１００重量部に対して）からなる耐摩耗性被覆材組成物に関する。
【０００９】
以下に本発明を詳細に説明する。
まず、最初に本発明の紫外線硬化性被覆材の製造に用いる各成分について説明する。
（ａ−１）成分について
（ａ−１）成分であるコロイダルシリカ微粒子は、一次粒子径が１〜２００ｍμの無水ケイ酸の超微粒子を水又は有機溶媒に分散させたものである。コロイダルシリカに使用される分散媒としては、水、メタノール、エタノール、イソプロパノール、ｎ−プロパノール、イソブタノール、ｎ−ブタノールなどのアルコール系溶剤、エチレングリコールなどの多価アルコール系溶剤、エチルセロソルブなどの多価アルコール誘導体、ジアセトンアルコールなどのケトン系溶剤、２−ヒドロキシエチルアクリレート、２−ヒドロキシプロピルアクリレートなどのモノマー類があるが、中でも炭素数３以下のアルコール系溶剤が（ａ−２）成分との反応工程上特に好ましい。これらのコロイダルシリカは、公知の方法で製造され、市販をされている。粒子径は１〜２００ｍμのものが好ましく、５〜８０ｍμのものが特に好ましい。粒子径が１ｍμに満たないものは（ａ−２）成分との反応工程においてゲル化が起こりやすく、また、粒子径が２００ｍμを超えるものは、被膜の透明性が低下する。
【００１０】
コロイダルシリカは、硬化被膜の耐摩耗性を著しく改善でき、特に、ケイ砂等の微粒子に対する耐摩耗性の改善効果が大きい。しかし、コロイダルシリカを単独で硬化被膜とした場合には、合成樹脂成形品表面に対する密着性が劣る。
【００１１】
（ａ−２）成分について
（ａ−２）成分である一般式（Ｉ）で示される単量体の加水分解物は、（ａ−１）成分であるコロイダルシリカと被覆材組成物の（Ｂ）成分である１分子中に２個以上の（メタ）アクリロイルオキシ基を有する多官能（メタ）アクリレートとの相溶性を向上させる成分である。紫外線照射により重合活性を示すアクリロイル基、メタクリロイル基又はビニル基を有するシラン化合物を用いることで、（Ｂ）成分の多官能（メタ）アクリレートとの化学結合形成が可能であり、硬化被膜に強靱性を付与することができる。さらに、コロイダルシリカと併用することで硬化被膜の耐摩耗性をさらに向上でき、特に、スチールウール等の金属繊維に対する耐摩耗性の改善効果が大きい。
【００１２】
（ａ−２）成分の具体例としては、３−メタクリロキシプロピルトリメトキシシラン、３−アクリロキシプロピルトリメトキシシラン、２−メタクリロキシエチルトリメトキシシラン、２−アクリロキシエチルトリメトキシシラン、３−メタクリロキシプロピルトリエトキシシラン、３−アクリロキシプロピルトリエトキシシラン、２−メタクリロキシエチルトリエトキシシラン、２−アクリロキシエチルトリエトキシシラン、３−メタクリロキシプロピルメチルジメトキシシラン、３−アクリロキシプロピルメチルジメトキシシランなどから選択される少なくとも１種のシラン化合物である。
【００１３】
次に、紫外線硬化性シリコンの製法について説明する。
この製法における最初の工程は（ａ−２）成分である一般式（Ｉ）で示されるるシラン化合物を加水分解させる工程である。この工程におけるシラン化合物の加水分解は、
（１）シラン化合物１モルに対してアルコール溶媒等の有機溶媒の存在下又は非存在下において、０．５〜６モルの０．００１〜０．１規定塩酸又は酢酸水溶液等の加水分解触媒を加え、常温又は加熱下で攪拌し加水分解した後コロイダルシリカを加える方法。
（２）（ａ−１）成分のコロイダルシリカ及び（ａ−２）成分のシラン化合物に、加水分解触媒を加え常温又は還流下で攪拌するなどの常法によって得ることができる。
【００１４】
このようにして得られたシラン化合物の加水分解物とコロイダルシリカ微粒子との反応について具体的に説明する。この反応は、常圧下又は減圧下で水、アルコール等の揮発分（極性溶媒）を留出させ、次いで、この反応で脱水により副生する水の脱水量が理論留出量（理論値）の３０〜８０％となった時点でコロイダルシリカの分散媒を常圧又は減圧下で非極性溶媒とともに共沸留出させ、分散媒を非極性溶媒に置換する。次いで、分散媒を非極性溶媒に置換した後、６０〜１５０℃、好ましくは８０〜１３０℃の温度で固形分を３０〜９０重量％、好ましくは５０〜８０重量％に保ちながら、脱水量が理論値の３０〜８０％となるまで、０．５〜１０時間攪拌して縮合反応させる。なお、この縮合反応においては、必要により反応を促進させる目的で酸、塩基、塩等の触媒を添加してもよい。
【００１５】
上記の反応において、脱水量が理論値の３０％未満では、非極性溶媒中での脱水縮合を十分に行わせることが難しく、このような縮合物を用いた被覆材からは耐候性、耐摩耗性の良好な塗膜を形成することが難しい。一方極性溶媒中で（ａ−１）成分のコロイダルシリカと（ａ−２）成分のシラン化合物との縮合を脱水量が理論値の８０％を越えて行わせることは極めて難しい。
【００１６】
本発明に用いられる非極性溶媒とは、誘電率、双極子能率あるいは水素結合パラメータを基準として選ばれるものであり、広義には、中程度の極性を有する溶媒も本発明に含まれるものである。例えば、２０℃の誘電率が２〜１０の範囲の非極性溶媒が本発明においては特に好ましい溶媒である。
【００１７】
非極性溶媒の具体例としては、ベンゼン、トルエン、キシレン、エチルベンゼン、シクロヘキサン等の炭化水素類；トリクロルエチレン、テトラクロルエチレン等のハロゲン化炭化水素類；１，４−ジオキサン、ジブチルエーテル等のエーテル類；メチルイソブチルケトン等のケトン類；酢酸ｎ−ブチル、酢酸イソブチル、プロピオン酸エチル等のエステル類；エチレングリコールモノブチルエーテル等の多価アルコール誘導体を挙げることができる。また、不飽和エチレン性化合物、例えば、１分子中に１個以上の（メタ）アクリロイルオキシ基を有する単量体を非極性溶媒として用いることもできる。これらの非極性溶媒の中でも芳香族炭化水素類が好ましく、特に好ましい非極性溶媒としてトルエンを挙げることができる。
【００１８】
非極性溶媒中でシラン化合物の加水分解物とコロイダルシリカ微粒子とを反応させることで硬化性が改善され、比較的厚膜下で紫外線吸収剤等の光安定剤存在下においても透明な硬化被膜の形成が可能となる。本発明以外の方法で製造された紫外線硬化性被覆材は硬化性が十分ではなく、厚膜になると透明性の低下やクラックの発生等外観欠陥が起こりやすく、また、硬化被膜の耐摩耗性や耐久性、耐候性に問題がある。
【００１９】
本発明の紫外線硬化性被覆材を用いた被覆材組成物は、硬化性に優れるばかりでなく、硬化被膜の耐摩耗性や耐久性、さらには耐候性においても優れるものである。
【００２０】
縮合反応での固形分濃度、すなわち（ａ−２）成分の固形分（シラノールとして換算）と（ａ−１）成分の固形分の合計量は３０〜９０重量％となる範囲である。固形分濃度が３０重量％未満、すなわち非極性溶媒が７０重量％を超える場合、反応が不十分なことがあり、厚膜下での硬化被膜の透明性に劣る。逆に、固形分濃度が９０重量％を超えると、急激な反応が起こる場合があり、ゲルの生成等の問題が生じる。
【００２１】
また、縮合反応での温度は、６０〜１５０℃の範囲が好ましい。反応温度が６０℃未満の場合、反応が不十分なことがあり、反応に長時間を要する。逆に反応温度が１５０℃を超えるとシリコンの縮合以外の反応が生じたり、又はゲルの生成等の問題が生じる。
【００２２】
縮合反応での（ａ−１）成分の固形分と（ａ−２）成分の固形分（シラノールとして換算）との使用割合は、（ａ−１）／（ａ−２）＝４０〜９０／６０〜１０重量％（合計１００重量％）、好ましくは５０〜８０／５０〜２０重量％である。使用割合が上記の範囲をはずれた場合、例えば、（ａ−１）成分が９０重量％を超えると反応系が白濁したり、ゲルの生成等の問題が生じ、逆に、４０重量％未満の場合は、反応が不十分なことがあり、被膜を厚く形成した場合、硬化被膜の透明性が低下することがある。また、（ａ−１）成分が９０重量％を超えると硬化被膜にクラックが発生しやすくなったり、逆に、４０重量％未満の場合は、硬化被膜の耐摩耗性や透明性が低下する。
【００２３】
次に本発明の被覆材組成物について説明する。
【００２４】
（Ａ）成分について
（Ａ）成分である紫外線硬化性被覆材は、上記の製法によって得られるものであり、硬化被膜の耐摩耗性、耐候性、耐久性を改善する成分である。（Ａ）成分の使用割合（固形分）は（Ａ）成分及び（Ｂ）成分からなる被覆材組成物１００重量部中５〜５０重量部、好ましくは１０〜４０重量部である。（Ａ）成分の使用割合が被覆材組成物中５重量部未満の場合、十分な耐摩耗性、耐候性及び耐久性の改善効果が得られず、逆に、５０重量部を超えるときは硬化被膜にクラックの発生が認められる。
【００２５】
（Ｂ）成分について
（Ｂ）成分である１分子中に２個以上の（メタ）アクリロイルオキシ基を有する多官能単量体又は単量体混合物は、耐摩耗性を低下させることなく、硬化被膜の強靱性、密着性を改善する成分である。（Ａ）成分のみから形成される硬化被膜は、耐摩耗性は優れるものの密着性が十分でなく、またクラック等が発生し易く、実用的な硬化被膜の形成は困難である。
【００２６】
（Ｂ）成分の具体例としては、ビス（２−アクリロキシエチル）−ヒドロキシエチル−イソシアヌレート、１，６−ヘキサンジオールジアクリレート、１，４−ブタンジオールジアクリレート、１，９−ノナンジオールジアクリレート、ネオペンチルグリコールジアクリレート、ヒドロキシピバリン酸ネオペンチルグリコールジアクリレート、ウレタンアクリレートなどの２官能性単量体；トリメチロールプロパントリアクリレート、ペンタエリスリトールトリアクリレート、トリス（アクリロキシエチル）イソシアヌレート、ジトリメチロールプロパンテトラアクリレート、ペンタエリスリトールテトラアクリレート、ジペンタエリスリトールヘキサアクリレート、ウレタンアクリレート、多価アルコールと多塩基酸及び（メタ）アクリル酸とから合成されるエステル化合物、例えばトリメチロールエタン／コハク酸／アクリル酸＝２／１／４モルから合成されるエステル化合物等の３官能以上の多官能単量体等が挙げられる。他には、ＵＶ．ＥＢ硬化ハンドブック−原料編（高分子刊行会）に記載してあるものを挙げることができる。
【００２７】
これらの多官能単量体の中でも、ビス（２−アクリロキシエチル）−ヒドロキシエチルイソシアヌレート、トリス（アクリロキシエチル）イソシアヌレートが硬化被膜の強靱性、耐候性及び耐久性の改善効果が大きいため特に好ましいものである。さらに、この両方の多官能単量体に１，９−ノナンジオールジアクリレートの３種を併用した単量体混合物が耐候性、耐久性及び基材との密着性に優れるため特に好ましい。
【００２８】
（Ｂ）成分の使用割合は（Ａ）成分及び（Ｂ）成分からなる被覆材組成物１００重量部中、９５〜５０重量部、好ましくは９０〜６０重量部である。（Ｂ）成分の使用割合が被覆材組成物中、５０重量部未満では十分な強靱性、密着性、耐熱性及び耐候性を有する硬化被膜が得られず、逆に、９５重量部を超えると耐摩耗性が低下する。
【００２９】
（Ｃ）成分について
本発明の被覆材組成物には光重合開始剤（Ｃ）成分を配合する。（Ｃ）成分の具体例としては、ベンゾイン、ベンゾインメチルエーテル、ベンゾインエチルエーテル、ベンゾインイソプロピルエーテル、ベンゾインイソブチルエーテル、アセトイン、ブチロイン、トルオイン、ベンジル、ベンゾフェノン、ｐ−メトキシベンゾフェノン、ジエトキシアセトフェノン、α，α−ジメトキシ−α−フェニルアセトフェノン、メチルフェニルグリオキシレート、エチルフェニルグリオキシレート、４，４−ビス（ジメチルアミノベンゾフェノン）、２−ヒドロキシ−２−メチル−１−フェニルプロパン−１−オン、１−ヒドロキシシクロヘキシルフェニルケトン、１−（４−イソプロピルフェニル）−２−ヒドロキシ−２−メチルプロパン−１−オン等のカルボニル化合物；テトラメチルチウラムジスルフィド等の硫黄化合物；アゾビスイソブチロニトリル、アゾビス−２，４−ジメチルバレロニトリル等のアゾ化合物；ベンゾイルパーオキシド、ジターシャリーブチルパーオキシド等のパーオキシド化合物；２，４，６−トリメチルベンゾイルジフェニルホスフィンオキサイド等のホスフィンオキサイド化合物を挙げることができる。
【００３０】
光重合開始剤（Ｃ）成分の中でも、２，４，６−トリメチルベンゾイルジフェニルホスフィンオキサイドと他の光重合開始剤を併用して用いることが、耐候性、耐久性の面で好ましい。
【００３１】
（Ｃ）成分の使用割合は、（Ａ）成分と（Ｂ）成分との合計１００重量部に対して０．０１〜５重量部、好ましくは０．１〜３重量部である。（Ｃ）成分の使用割合が５重量部を超えると硬化被膜の着色や耐候性が低下する。
【００３２】
以上が本発明の被覆材組成物を構成する必須な成分であるが、さらに、耐候性及び耐久性を改善する目的で本発明の被覆材組成物に紫外線吸収剤及び光安定剤を添加することができる。使用される紫外線吸収剤は特に限定されず、被覆材組成物に均一に溶解し、かつその耐候性が良好なものであれば使用可能であるが、被覆材組成物に対する良好な溶解性及び耐候性改善効果という点から、ベンゾフェノン系、ベンゾトリアゾール系、サリチル酸フェニル系、安息香酸フェニル系から誘導された化合物で、それらの最大吸収波長が２４０〜３８０ｎｍの範囲である紫外線吸収剤が好ましい。特に、被覆材組成物に多量に含有させることができるという点からベンゾフェノン系の紫外線吸収剤が、またポリカーボネート等の基材の黄変を防ぐことができるという点から、ベンゾトリアゾール系の紫外線吸収剤が好ましい。
【００３３】
紫外線吸収剤の具体例としては、２−ヒドロキシベンゾフェノン、５−クロロ−２−ヒドロキシベンゾフェノン、２，４−ジヒドロキシベンゾフェノン、２−ヒドロキシ−４−メトキシベンゾフェノン、２−ヒドロキシ−４−オクチロキシベンゾフェノン、４−ドデシロキシ−２−ヒドロキシベンゾフェノン、２−ヒドロキシ−４−オクタデシロキシベンゾフェノン、２，２′−ジヒドロキシ−４−メトキシベンゾフェノン、２，２′−ジヒドロキシ−４，４′−ジメトキシベンゾフェノン、フェニルサリシレート、ｐ−ｔｅｒｔ．−ブチルフェニルサリシレート、ｐ−（１，１，３，３−テトラメチルブチル）フェニルサリシレート、３−ヒドロキシフェニルベンゾエート、フェニレン−１，３−ジベンゾエート、２−（２−ヒドロキシ−５−メチルフェニル）ベンゾトリアゾール、２−（２−ヒドロキシ−５−ｔｅｒｔ．−ブチルフェニル）ベンゾトリアゾール、２−（２−ヒドロキシ−３，５−ジ−ｔｅｒｔ．−ブチルフェニル）−５−クロロベンゾトリアゾール、２−（２−ヒドロキシ−３，５−ジ−ｔｅｒｔ．−ブチルフェニル）ベンゾトリアゾール、２−（２−ヒドロキシ−５−ｔｅｒｔ．−オクチルフェニル）ベンゾトリアゾール等が挙げられる。これらは２種以上を組み合わせて使用してもよい。
【００３４】
光安定剤としてヒンダードアミン系光安定剤を使用することができる。この光安定剤は、紫外線吸収剤と併用して用いることで、硬化被膜の耐候性をより向上させる。ヒンダードアミン系光安定剤の具体例としては、ビス（１，２，２，６，６−ペンタメチル−４−ピペリジル）セバケート、ビス（２，２，６，６−テトラメチル−４−ピペリジル）セバケート、２−（３，５−ジ−ｔｅｒｔ．−ブチル−４−ヒドロキシベンジル）−２−ｎ−ブチルマロン酸ビス（１，２，２，６，６−ペンタメチル−４−ピペリジル）等が挙げられるが、これらの内、ビス（１，２，２，６，６−ペンタメチル−４−ピペリジル）セバケート、ビス（２，２，６，６−テトラメチル−４−ピペリジル）セバケートが特に好ましい。
【００３５】
本発明の被覆材組成物には、さらに必要に応じて、有機溶剤、酸化防止剤、黄変防止剤、ブルーイング剤、顔料、レベリング剤、消泡剤、増粘剤、沈降防止剤、帯電防止剤、防曇剤等の各種の添加剤が含まれていてもよい。
【００３６】
有機溶剤は被覆材組成物の均一溶解性、分散安定性、さらには基材との密着性及び被膜の平滑性、均一性などの面から、被覆材組成物中に配合して用いられ、有機溶剤として特に限定されるものではなく、上記性能を満足するものであればよい。具体的には、アルコール系、炭化水素系、ハロゲン化炭化水素系、エーテル系、ケトン系、エステル系、多価アルコール誘導体等の有機溶剤を挙げることができる。
【００３７】
本発明の被覆材組成物を基材に塗布するには、ハケ塗り、スプレーコート、ディップコート、スピンコート、カーテンコートなどの方法が用いられる。
【００３８】
被覆材組成物の塗布量としては、硬化被膜の膜厚が３〜３０μｍ、好ましくは５〜２５μｍ、特に好ましくは８〜２０μｍである。硬化被膜の膜厚が３μｍ未満では十分な耐摩耗性が得られず、３０μｍを超える場合は、基材との密着性が低下したり、被膜にクラックが発生しやすくなったりする。
【００３９】
基材に塗布された被膜を硬化させる手段としては、α，β及びγ線などの活性エネルギー線を照射する公知の方法が用いられるが、本発明の被覆材組成物を硬化させる手段としては紫外線を用いることが好ましい。紫外線発生源としては実用的、経済性の面から紫外線ランプが一般に用いられており、具体的には、低圧水銀ランプ、高圧水銀ランプ、超高圧水銀ランプ、キセノンランプ、メタルハライドランプなどが挙げられる。照射する雰囲気は空気中でもよいし、窒素、アルゴン等の不活性ガス中でもよい。
【００４０】
合成樹脂成形品表面に本発明の被覆材組成物を塗布した後、紫外線放射エネルギーにて硬化させる前に、硬化被膜の基材に対する密着性向上を目的として、赤外線又は熱風乾燥炉を用いて、２０℃〜１２０℃で１分〜６０分間の熱処理を行ってもよい。
【００４１】
本発明の被覆材組成物は、基材たる各種の合成樹脂成形品の表面の改質に使用できるが、この合成樹脂成形品としては、従来から耐摩耗性や耐候性等の改善の要望のある各種の熱可塑性樹脂や熱硬化性樹脂が挙げられる。具体例には、ポリメチルメタクリレート樹脂、ポリカーボネート樹脂、ポリエステル樹脂、ポリエチレン樹脂、ＡＢＳ樹脂、アクリロニトリル−スチレン共重合樹脂、ポリアミド樹脂、ポリアリレート樹脂、ポリメタクリルイミド樹脂、ポリアリルジグリコールカーボネート樹脂などが挙げられる。なかんずく、ポリメチルメタクリレート樹脂、ポリカーボネート樹脂、ポリスチレン樹脂、ポリメタクリルイミド樹脂は、透明性に優れ、かつ耐摩耗性改良要求も強いため、本発明の被覆材組成物の基材として用いるのが特に有効である。また合成樹脂成形品とは、これらの樹脂からなるシート状成形品、フィルム状成形品、各種射出成形品などである。
【００４２】
【実施例】
以下の実施例により、本発明をさらに詳しく説明する。なお、実施例中の評価は次のような方法で行った。なお、例中の部は重量部を表わす。
【００４３】
１．耐摩耗性
（１）テーバー摩耗テスト
ＡＳＴＭ Ｄ−１０４４に準拠し、摩耗輪ＣＳ−１０Ｆ、荷重５００ｇ、回転数５００サイクルの条件で摩耗テストを行った。摩耗した後、試料を中性洗剤を用いて洗浄し、ヘーズメータで曇価を測定した。耐摩耗性は（摩耗後の曇価−摩耗前の曇価）で示される。
（２）スチールウールテスト
＃０００スチールウール（日本スチールウール（株）製、ボンスター（登録商標））を１ｃｍ^２ の円形パッドに装着し、往復式摩耗試験機台上に保持された試料表面にこのパッドを置いて荷重１，０００ｇ下で５０サイクル摩耗した。この試料を中性洗剤を用いて洗浄し、ヘーズメータで曇価を測定した。耐摩耗性は（摩耗後の曇価−摩耗前の曇価）で示される。
【００４４】
２．密着性
試料表面にカミソリで縦及び横にそれぞれ１１本の１．５ｍｍ間隔で基材に達する傷を入れ、１００個のます目をつくり、セロハンテープ（巾２５ｍｍ、ニチバン（株）製）をます目に対して圧着させて上方に急激にはがす。密着性の評価は、
残存ます目数／全ます目数（１００）で示す。
【００４５】
３．外観
（１）透明性
ＡＳＴＭ Ｄ−１００３に準拠し、ヘーズメータを用いて曇価で示す。
（２）クラック
目視で観察し、以下の判定基準とした。
○…クラックの発生なし
△…若干のクラックの発生あり
×…無数のクラックの発生あり
【００４６】
４．熱水性テスト
８０℃の熱水に２時間浸漬し、次いで熱水から取り出した後、室温で１時間放置後、被膜の透明性とクラックについて目視観察し、更に密着性について評価した。
【００４７】
５．耐候性テスト
サンシャインウエザオメータ（スガ試験機（株）製、ＷＥＬ−ＳＵＮ−ＤＣ型）を用い、ブラックパネル温度６３℃、降雨１２分／６０分、サイクルの試験条件で２，０００時間加速暴露テストを行った。暴露終了サンプルについて透明性を曇価で示し、被膜のクラックについては目視にて観察し、さらに密着性について評価した。
【００４８】
実施例１
紫外線硬化性被覆材の調製（Ｉ）
攪拌棒、温度計及びコンデンサーを備えた３リットルの４ツ口フラスコに、イソ−プロパノールシリカゾル（分散媒：イソ−プロパノール，ＳｉＯ_２ 濃度；３０重量％、一次粒子径；１２ｍμ、商品名；ＩＰＡ−ＳＴ、日産化学工業（株）製）（以下、ＩＰＡ−ＳＴと略称する。）２，０００ｇと、３−メタクリロキシプロピルトリメトキシシラン（商品名；Ａ−１７４、日本ユニカー（株）製）（以下、Ａ−１７４と略称する。）３８２ｇを入れ攪拌しながら昇温させ、揮発成分の還流が始まると同時に０．００１規定の塩酸水溶液１３９ｇを徐々に滴下させ、滴下終了後、還流下で２時間攪拌しながら加水分解を行った。加水分解終了後、得られた液状物から常圧下でアルコール及び水等の揮発成分を留出させ、脱水量が理論値の７０％となった時点でトルエン６００ｇを追加し共沸留出させた。更に、トルエン１，２００ｇを数回に分けて追加し、完全に溶媒置換を行い、トルエンの分散系とした。このときの固形分（ＳｉＯ_２ ６００ｇとＡ−１７４シラノール３１７ｇの合計量９１７ｇ）濃度は約６０重量％であった。次に、反応系を昇温させ、トルエンを留出させ脱水量が理論値の８０％となった時点で１１０℃で４時間反応を行った。なお、この反応の過程で、固形分を約６０重量％に保持するためにトルエンを数回に分けて追加し、固形分の調整を行った。反応終了後、固形分量を高めるために、減圧下でトルエン等揮発成分を留出させ、最終的な固形分を７０重量％とした。得られた紫外線硬化性被覆材（以下、反応液（Ｉ）という。）は、濃褐色状でニュートン流体の透明、粘稠な液体であり、２５℃の粘度は８，０００センチポイズであった。また、固形分濃度は、加熱残分（％）で計算したところ７１％であった。
なお、加熱残分（％）は、（加熱後の重量（ｇ）／加熱前の重量（ｇ））×１００（％）で示し、加熱条件は１０５℃で３時間である。また、以下の実施例及び比較例における固形分濃度は加熱残分（％）で示す。
【００４９】
実施例２
紫外線硬化性被覆材の調製（ＩＩ）
実施例１の組成及び反応条件を用いて加水分解を行った。
加水分解終了後、得られた液状物から常圧下でアルコール及び水等の揮発成分を留出させ、脱水量が理論値の７０％となった時点で酢酸ｎ−ブチル６００ｇを追加し共沸留出させた。さらに、酢酸ｎ−ブチル１２００ｇを数回に分けて追加し、完全に溶媒置換を行い、酢酸ｎ−ブチルの分散系とした。このときの固形分濃度は約６５重量％であった。次に、反応系を昇温させ、酢酸ｎ−ブチルを留出させ、脱水量が理論値の８０％となった時点で１２６℃で３時間反応を行った。なお、この反応の過程で、固形分を約６５重量％に保持するために酢酸ｎ−ブチルを数回に分けて追加し、固形分の調整を行った。反応終了後、固形分量を高めるために減圧下で酢酸ｎ−ブチル等揮発成分を留出させ、最終的な固形分を約６８重量％とした。得られた紫外線硬化性被覆材（以下、反応液（ＩＩ）という。）は、濃橙色状でニュートン流体の透明、粘稠な液体であり、２５℃の粘度が約４，０００センチポイズであった。また、固形分濃度は加熱残分で６８％であった。
【００５０】
実施例３
紫外線硬化性被覆材の調製（ＩＩＩ ）
実施例１の組成及び反応条件を用いて加水分解を行った。
加水分解終了後、得られた液状物から常圧下でアルコール及び水等の揮発成分を留出させ、脱水量が理論値の７０％となった時点でメチルイソブチルケトン６００ｇを追加し共沸留出させた。さらに、メチルイソブチルケトン１，２００ｇを数回に分けて追加し、完全に溶媒置換を行い、メチルイソブチルケトンの分散系とした。このときの固形分濃度は約６０重量％であった。次に、反応系を昇温させ、メチルイソブチルケトンを留出させ、脱水量が理論値の８０％となった時点で１１６℃で４時間反応を行った。なお、この反応の過程で、固形分を約６０重量％に保持するためにメチルイソブチルケトンを数回に分けて追加し、固形分の調整を行った。反応終了後、固形分を高めるために、減圧下でメチルイソブチルケトン等揮発成分を留出させ、最終的な固形分を約６９重量％とした。得られた紫外線硬化性被覆材（以下、反応液（ＩＩＩ ）という。）は、濃い橙色のニュートン流体の透明、粘稠な液体であり、２５℃の粘度は約２，５００センチポイズであった。また、固形分濃度は加熱残分で６９％であった。
【００５１】
比較例１
紫外線硬化性被覆材の調製（ＩＶ）
ＩＰＡ−ＳＴ１，０００ｇ、Ａ−１７４ １９１ｇ及び０．００１規定の塩酸水溶液６９．５ｇを攪拌棒、温度計及びコンデンサーを備えた２リットルの４ツ口フラスコに入れ、常温で４時間攪拌しながら加水分解を行った。加水分解後、この液状物を常温で２日間放置し、熟成させた後、固形分濃度を調整するために、４０℃の減圧下においてアルコール及び水を留出させた。得られた反応液（以下、反応液（ＩＶ）という。）は、淡い桃色の透明液体で、２５℃の粘度は約１５０センチポイズであり、固形分濃度は加熱残分で７０％であった。
【００５２】
比較例２
紫外線硬化性被覆材の調製（Ｖ）
ＩＰＡ−ＳＴ１，０００ｇ及びＡ−１７４ １９１ｇを比較例１で使用したのと同一の４ツ口フラスコに入れ、常温で４時間攪拌して加水分解を行った。加水分解後、この液状物を常温で４日間放置して熟成させた。得られた反応液（以下、反応液（Ｖ）という。）は無色透明で、２５℃の粘度は５センチポイズであり、固形分濃度は加熱残分で３７％であった。
【００５３】
比較例３
紫外線硬化性被覆材の調製（ＶＩ）
ＩＰＡ−ＳＴ１，０００ｇ及びＡ−１７４ １９１ｇを比較例１で使用したのと同一の４ツ口フラスコに入れ、攪拌しながら昇温した。揮発成分の還流が始まると同時に、０．００１規定の塩酸水溶液６９．５ｇを徐々に滴下し、滴下終了後、攪拌を続けながら還流下で２時間加水分解を行った。加水分解終了後、得られた液状物を常圧下で水及びアルコール等の揮発成分を留出させ、脱水量が理論値の４０％となるまで留出させた。引続き残りの揮発成分を還流下（８０〜８３℃）で還流させながら２時間反応させた。得られた反応液（以下、反応液（ＶＩ）という。）は、桃色の透明液体で、２５℃の粘度は１００センチポイズであり、固形分濃度は加熱残分で６６．５％であった。
【００５４】
比較例４
紫外線硬化性被覆材の調製（ＶＩＩ ）
比較例３の組成及び反応条件を用いて加水分解を行った。
加水分解終了後、得られた液状物から常圧下でアルコール及び水等の揮発成分を留出させ、脱水量が理論値の７０％となった時点でトルエン３００ｇを追加し共沸留出させた。さらに、トルエン６００ｇを数回に分けて追加し、完全に溶媒置換を行い、トルエンの分散系とした。このときの固形分濃度は約６５重量％であった。次に、反応系を昇温させ、トルエンを留出させながら、１１０℃で反応を続けたところ、高粘度状態となり、最後にゲル化した。この時の固形分濃度は加熱残分で９６％であった。
【００５５】
比較例５
紫外線硬化性被覆材の調製（ＶＩＩＩ）
ＩＰＡ−ＳＴ３００ｇ、Ａ−１７４ ５７．３ｇ及び０．００１規定塩酸水溶液１２．５ｇを用いて、比較例３と同様にして加水分解を行った。
加水分解終了後、得られた液状物から常圧下でアルコール及び水等の揮発成分を留出させ、脱水量が理論値の７０％となった時点で酢酸ｎ−ブチル２００ｇを追加し共沸留出させた。さらに、酢酸ｎ−ブチル１５００ｇを数回に分けて追加し、完全に溶媒置換を行い、酢酸ｎ−ブチルの分散系とした。このときの固形分濃度は約１０重量％であった。次に、反応系の温度を９０℃に保持し、２時間反応させた。
得られた反応液（以下、反応液（ＶＩＩＩ）という。）は、橙色の透明液体で２５℃の粘度は２．５センチポイズであった。また、固形分濃度は加熱残分で１３．８％であった。
【００５６】
比較例６
紫外線硬化性被覆材の調製（ＩＸ）
比較例３の組成及び反応条件を用いて加水分解を行った。
加水分解終了後、得られた液状物から常圧下でアルコール及び水等の揮発成分を留出させ、脱水量が理論値の７０％となった時点でエチルセロソルブ３００ｇを追加し共沸留出させた。さらに、エチルセロソルブ６００ｇを数回に分けて追加し、完全に溶媒置換を行い、エチルセロソルブの分散系とした。このときの固形分濃度は約６５重量％であった。次に、反応系を昇温させ、１２０℃で２時間反応を行った。
得られた紫外線硬化性被覆材（以下、反応液（ＩＸ）という。）は、橙色の透明液で、２５℃の粘度は８０センチポイズであった。また、固形分濃度は加熱残分で６３％であった。
【００５７】
比較例７
紫外線硬化性被覆材の調製（Ｘ）
ＩＰＡ−ＳＴ ２５０ｇ（ＳｉＯ_２ ７５ｇ）、Ａ−１７４ ３６１．２ｇ及び０．００１規定塩酸水溶液７８．６ｇを用いて、比較例３と同様にして加水分解を行った。
加水分解終了後、常圧下でアルコール及び水等の揮発成分を留出させ、脱水量が理論値の７０％となった時点でトルエン３００ｇを追加し共沸留出させた。さらに、トルエン６００ｇを数回に分けて追加し、完全に溶媒置換を行い、トルエンの分散系とした。このときの固形分濃度は約８５重量％であった。次に、反応系を昇温させ、９０℃で４時間反応を行った。得られた紫外線硬化性被覆材（以下、反応物（Ｘ）という。）は、淡褐色透明液体で２５℃の粘度は、２５０センチポイズであった。また、固形分濃度は加熱残分で８２％であった。
【００５８】
実施例４
紫外線硬化性被覆材の調製（ＸＩ）
実施例１の４ツ口フラスコに、メタシリカゾル（分散媒；メタノール、ＳｉＯ_２ 濃度３０重量％、一次粒子径；１２μｍ、商品名；メタノールシリカゾル、日産化学工業（株）製）２，０００ｇ、Ａ−１７４ ３８２．９ｇを入れ、実施例１の方法に準じて加水分解を行った。
加水分解終了後、得られた液状物から常圧下でアルコール及び水等の揮発成分を留出させ、脱水量が理論値の７０％となった時点でトルエン６００ｇを追加し共沸留出させた。さらに、トルエン１２００ｇを数回に分けて追加し、完全に溶媒置換を行い、トルエンの分散系とした。このときの固形分濃度は約７０重量％であった。次に、反応系を昇温させ、トルエンを留出させ、脱水量が理論値の８０％となった時点で８５℃で４時間反応を行った。なお、この反応の過程で、固形分を約７０％に保持するためにトルエンを数回に分けて追加し、固形分の調整を行った。反応終了後、固形分を高めるために、減圧下でトルエン等揮発成分を留出させ、最終的な固形分を８０重量％とした。得られた紫外線硬化性被覆材（以下、反応液（ＸＩ）という。）は、橙色のニュートン流体を示す透明液体であり、２５℃の粘度は２，５００センチポイズであった。また、固形分濃度は加熱残分で８２％であった。
【００５９】
実施例５〜１２、比較例８〜１６
上記実施例及び比較例で得られた反応液を用いて、表１に示すような組成を有する被覆材組成物を調製した。次いで、この被覆材組成物をポリカーボネート樹脂（商品名レキサンＬＳ−２、色調１１１クリヤー、Ｇ．Ｅ．社製）の射出成形板（１００ｍｍ×１００ｍ×３ｍｍ（厚さ））にスプレー塗布し、室温で１０分間放置した後、熱風乾燥機中６５℃で５分間熱処理した。次いで、これを空気雰囲気下において高圧水銀灯（アイグラフィック社製）を用い、２，０００ｍＪ／ｃｍ^２ （波長３２０〜３８０ｎｍの紫外線積算エネルギー量）の紫外線を照射し、硬化被膜の厚さが１３μｍの耐摩耗性被膜を表面に有するポリカーボネート樹脂の射出成形板を得た。得られた評価結果を表２に示す。
【００６０】
実施例１１
上記実施例１で得られた反応液（Ｉ）を用いて、表１に示すような組成を有する被覆材組成物を調製した。次いで、この被覆材組成物をメタクリル樹脂（アクリペットＶＨ、色調００１、三菱レイヨン（株）製）の射出成形板（１００ｍｍ×１００ｍｍ×３ｍｍ（厚さ））にスプレー塗布し、室温で１０分間放置した後、熱風乾燥機中６０℃で５分間熱処理した。次いで、これを空気雰囲気下において高圧水銀灯（アイグラフィック社製）を用い、１６００ｍＪ／ｃｍ^２ の紫外線を照射し、硬化被膜の厚さが１２μｍの耐摩耗性被膜を表面に有するメタクリル樹脂の射出成形板を得た。得られた評価結果を表２に示す。
【００６１】
実施例１２
上記実施例１で得られた反応液（Ｉ）を用いて、表１に示すような組成を有する被覆材組成物を調製した。次いで、この被覆材組成物をポリメタクリルイミド樹脂（Ｐ５０Ｓ ０５、色調００３、三菱レイヨン（株）製）の射出成形板（１００ｍｍ×１２０ｍｍ×３ｍｍ（厚さ））に浸漬塗布し、室温で５分間放置した後、熱風乾燥機中６０℃で５分間熱処理した。次いで、これを空気雰囲気下において高圧水銀灯（アイグラフィック社製）を用い、２０００ｍＪ／ｃｍ^２ の紫外線を照射し、硬化被膜の厚さが１０μｍの耐摩耗性被膜を表面に有するポリメタクリルイミド樹脂の射出成形板を得た。得られた評価結果を表２に示す。
なお、表１中の略記号は以下の化合物を表わす。
【００６２】
ＦＡ−７３１Ａ：トリス（アクリロキシエチル）イソシアヌレート（日立化成工業（株）製）
Ｍ−２１５：ビス（２−アクリロキシエチル）−ヒドロキシエチルイソシアヌレート（東亜合成化学工業（株）製）
Ｃ_９ −ＤＡ：１，９−ノナンジオールジアクリレリート（商品名ビスコート＃２６０、大阪有機化学工業（株）製）
Ｌｕｃｉｒｉｎ−ＴＰＯ：２，４，６−トリメチルベンゾイルジフェニルホスフィンオキサイド（ＢＡＳＦ社製）
バイキュアー５５：メチルフェニルグリオキシド（ストウファー社製）
チヌビン−ＰＳ：２−（ヒドロキシ−５−ｔ−ブチルフェニル）ベンゾトリアゾール（チバガイギー社製）
サノールＬＳ−７７０：ビス（２，２，６，６−テトラメチル−４−ピペリジル）セバケート（三共（株）製）
【００６３】
【表１】

【００６４】
【表２】

【００６５】
【発明の効果】
以上説明したように、本発明の製法により得られた紫外線硬化性被覆材及びそれを用いた被覆材組成物は、硬化性に優れるばかりでなく、合成樹脂成形品の耐摩耗性改善効果に優れるものであり、耐久性、耐候性の要求の強い自動車関連部品、特に前照灯用レンズカバーやテールランプあるいはサイドランプなどの用途に特に有用である。[0001]
[Industrial applications]
The present invention provides a method for producing a UV-curable coating material, and UV irradiation using the same, on the surface of the substrate, abrasion resistance, surface smoothness, heat resistance, chemical resistance, durability, weather resistance and the substrate. The present invention relates to a coating material composition capable of forming a crosslinked cured film having excellent adhesion.
[0002]
[Prior art]
Synthetic resin molded products made from polymethyl methacrylate resin, polymethacrylimide resin, polycarbonate resin, polystyrene resin, AS resin, etc. are not only lightweight and excellent in impact resistance but also excellent in transparency compared to glass products. In recent years, it has been used in various fields such as plastic materials for automobiles, taking advantage of various advantages such as easy molding.
[0003]
However, on the other hand, these synthetic resin molded products have insufficient abrasion resistance on the surface, so the surface is easily damaged by contact with other hard objects, friction, scratches, etc. Improving the wear resistance of the surface is strongly demanded because the commercial value of the product is significantly reduced or the product cannot be used for a short period of time. When used as the above-mentioned automotive material, the weather resistance is also an important performance.
[0004]
Various methods for improving the drawbacks of such synthetic resin molded articles have been studied in the past, for example, a method comprising a partially hydrolyzed condensate of a silane mixture containing alkyltrialkoxysilane as a main component and colloidal silica. A method is disclosed in which a coating material is applied to the surface of a molded article and then heat-treated to form a crosslinked cured film and improve the abrasion resistance (US Pat. No. 4,006,271). By this method, a high degree of abrasion resistance is obtained, but the adhesion to the surface of the molded article is often insufficient, and a polymer made of acrylic or silicon is used as a primer to improve the adhesion. And the process becomes complicated. Further, since the curing time is long, it is economically disadvantageous and productivity is poor. In order to improve this drawback, a UV-curable coating consisting of colloidal silica and alkoxysilane having a functional group of methacryloyl or glycidyl group, and a non-silyl acrylate is applied to the surface of the molded article, which is then irradiated with ultraviolet rays, and then subjected to abrasion resistance. For obtaining a functional synthetic resin molded article (Japanese Patent Publication No. 57-500984), and a coating containing substantially no organic solvent comprising a hydrolyzate of colloidal silica and silyl acrylate, a polyfunctional acrylate and a photopolymerization initiator A material composition and a method for producing the same (JP-A-58-1756) are disclosed. These methods are methods of curing using ultraviolet rays, have the advantage that the curing time of a silicon-based coating, which has been a problem in the past, can be greatly reduced, and are also an advantageous method for improving the wear resistance of a synthetic resin molded product. It is.
[0005]
However, among the above methods, although the former method can improve the productivity, it has a problem that it is not satisfactory with respect to the durability and weather resistance of the cured film, and further, before the coating material composition is applied. In addition, there is a problem that complicated processing steps cannot be improved in that the surface of the synthetic resin molded product is undercoated with the primer composition. Further, in the latter method, since the organic solvent is not substantially contained, the surface smoothness of the coating when applied to the surface of the synthetic resin molded product is inferior, and surface defects such as repelling and pinholes are easily generated. Further, since the curability is not sufficient, excessive ultraviolet energy is required, and the obtained cured product undergoes performance deterioration by a hot water test, a thermal cycle test, and a weather resistance test.
[0006]
As described above, at present, a coating material composition combining an inorganic component such as colloidal silica and an organic component such as an acrylic monomer cannot achieve both abrasion resistance improvement and durability and weather resistance of a cured film. there were.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above background, and its object is to provide excellent curability and abrasion resistance, surface smoothness, heat resistance, chemical resistance, durability, and weather resistance on a substrate surface. An object of the present invention is to provide a coating material composition capable of forming a crosslinked cured film having excellent properties and adhesion to a substrate, and a method for producing an ultraviolet-curable coating material used therefor.
[0008]
[Means for Solving the Problems]
The present inventors have conducted intensive studies and found that a UV curable coating material obtained by reacting colloidal silica and a radical polymerizable silane compound under specific conditions, a coating comprising a specific monomer and a photopolymerization initiator. After applying the material composition to the synthetic resin molded article and then irradiating it with ultraviolet light to cure it, it was found that a synthetic resin molded article excellent in abrasion resistance, weather resistance and curability was obtained, and the present invention was completed.
The present invention relates to (a-1) 40 to 90% by weight of colloidal silica fine particles (solid content), and (a-2) the following general formula (I):
Embedded image

(Where X is CH _Two ＣＨCH—COO— group, CH _Two = C (CH _Three ) -COO- group, or CH _Two = CH-group, R ₁ Is an alkylene group having 1 to 8 carbon atoms, R _Two , R _Three Represents an alkyl group having 1 to 8 carbon atoms, a represents a positive integer of 1 to 3, b represents a positive integer of 0 to 2, and a + b represents an integer of 1 to 3. )
And 60 to 10% by weight (total 100% by weight) of the monomer hydrolyzate (solid content) represented by The present invention relates to an ultraviolet-curable coating material obtained by replacing a polar solvent with a nonpolar solvent and further subjecting the nonpolar solvent to a condensation reaction in the presence of a solid content of 30 to 90% by weight.
Further, the present invention provides (A) the ultraviolet-curable coating material (solid content) of 5 to 50 parts by weight,
(B) 95 to 50 parts by weight of a polyfunctional monomer or monomer mixture having two or more (meth) acryloyloxy groups in one molecule, and
(C) The present invention relates to a wear-resistant coating composition comprising 0.01 to 5 parts by weight of a photopolymerization initiator (based on 100 parts by weight of the total of the above components (A) and (B)).
[0009]
Hereinafter, the present invention will be described in detail.
First, each component used for producing the ultraviolet-curable coating material of the present invention will be described.
(A-1) About the component
The colloidal silica fine particles as the component (a-1) are obtained by dispersing ultrafine silica anhydride particles having a primary particle diameter of 1 to 200 μm in water or an organic solvent. Examples of the dispersion medium used in the colloidal silica include water, alcohol solvents such as methanol, ethanol, isopropanol, n-propanol, isobutanol and n-butanol, polyhydric alcohol solvents such as ethylene glycol, and ethyl cellosolve. There are polyhydric alcohol derivatives, ketone solvents such as diacetone alcohol, and monomers such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate, and among them, alcohol solvents having 3 or less carbon atoms are mixed with the component (a-2). Particularly preferred in the reaction step. These colloidal silicas are produced by a known method and are commercially available. The particle diameter is preferably from 1 to 200 mμ, particularly preferably from 5 to 80 mμ. If the particle diameter is less than 1 μm, gelation tends to occur in the reaction step with the component (a-2), and if the particle diameter is more than 200 μm, the transparency of the coating film is reduced.
[0010]
Colloidal silica can significantly improve the abrasion resistance of the cured film, and particularly has a great effect of improving the abrasion resistance against fine particles such as silica sand. However, when colloidal silica is used alone as a cured coating, the adhesion to the surface of the synthetic resin molded product is poor.
[0011]
(A-2) About the component
The hydrolyzate of the monomer represented by the general formula (I) which is the component (a-2) is composed of the colloidal silica which is the component (a-1) and the (B) component of the coating material composition in one molecule which is the component (B). Is a component for improving the compatibility with a polyfunctional (meth) acrylate having two or more (meth) acryloyloxy groups. By using a silane compound having an acryloyl group, a methacryloyl group, or a vinyl group that exhibits polymerization activity by ultraviolet irradiation, a chemical bond can be formed with the polyfunctional (meth) acrylate of the component (B), and the cured film has toughness. Can be given. Further, the wear resistance of the cured film can be further improved by using it in combination with colloidal silica, and in particular, the effect of improving the wear resistance of metal fibers such as steel wool is great.
[0012]
Specific examples of the component (a-2) include 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 2-methacryloxyethyltrimethoxysilane, 2-acryloxyethyltrimethoxysilane, Methacryloxypropyltriethoxysilane, 3-acryloxypropyltriethoxysilane, 2-methacryloxyethyltriethoxysilane, 2-acryloxyethyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethyldimethoxy At least one silane compound selected from silane and the like.
[0013]
Next, a method for producing ultraviolet-curable silicon will be described.
The first step in this production method is a step of hydrolyzing the silane compound represented by the general formula (I), which is the component (a-2). The hydrolysis of the silane compound in this step is
(1) In the presence or absence of an organic solvent such as an alcohol solvent with respect to 1 mol of a silane compound, a hydrolysis catalyst such as an aqueous solution of 0.5 to 6 mol of 0.001 to 0.1 N hydrochloric acid or acetic acid is used. In addition, a method in which colloidal silica is added after stirring and hydrolysis at room temperature or under heating.
(2) It can be obtained by a conventional method such as adding a hydrolysis catalyst to the colloidal silica of the component (a-1) and the silane compound of the component (a-2) and stirring the mixture at room temperature or under reflux.
[0014]
The reaction between the hydrolyzate of the silane compound thus obtained and the colloidal silica fine particles will be specifically described. In this reaction, volatiles (polar solvents) such as water and alcohol are distilled off under normal pressure or reduced pressure, and then the amount of dewatering by-produced by dehydration in this reaction is reduced to the theoretical amount of distillation (theoretical value). At 30 to 80%, the dispersion medium of colloidal silica is azeotropically distilled together with the non-polar solvent under normal pressure or reduced pressure, and the dispersion medium is replaced with the non-polar solvent. Next, after replacing the dispersion medium with a non-polar solvent, the amount of dehydration is reduced while maintaining the solid content at 30 to 90% by weight, preferably 50 to 80% by weight at a temperature of 60 to 150 ° C, preferably 80 to 130 ° C. The condensation reaction is carried out by stirring for 0.5 to 10 hours until the theoretical value becomes 30 to 80%. In this condensation reaction, a catalyst such as an acid, a base, or a salt may be added for the purpose of accelerating the reaction if necessary.
[0015]
In the above reaction, when the dehydration amount is less than 30% of the theoretical value, it is difficult to sufficiently perform dehydration condensation in a non-polar solvent, and the coating material using such a condensate cannot provide weather resistance and abrasion resistance. It is difficult to form a coating film having good properties. On the other hand, it is extremely difficult to condense the colloidal silica of the component (a-1) with the silane compound of the component (a-2) in a polar solvent so that the dehydration amount exceeds 80% of the theoretical value.
[0016]
The non-polar solvent used in the present invention is selected based on the dielectric constant, dipole efficiency or hydrogen bonding parameter, and in a broad sense, a solvent having a medium polarity is also included in the present invention. . For example, a non-polar solvent having a dielectric constant at 20 ° C. in the range of 2 to 10 is a particularly preferred solvent in the present invention.
[0017]
Specific examples of the nonpolar solvent include hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and cyclohexane; halogenated hydrocarbons such as trichloroethylene and tetrachloroethylene; ethers such as 1,4-dioxane and dibutyl ether. Ketones such as methyl isobutyl ketone; esters such as n-butyl acetate, isobutyl acetate and ethyl propionate; and polyhydric alcohol derivatives such as ethylene glycol monobutyl ether. Further, an unsaturated ethylenic compound, for example, a monomer having one or more (meth) acryloyloxy groups in one molecule can be used as the non-polar solvent. Among these non-polar solvents, aromatic hydrocarbons are preferred, and toluene is a particularly preferred non-polar solvent.
[0018]
The curability is improved by reacting the hydrolyzate of the silane compound and the colloidal silica fine particles in a non-polar solvent, and a transparent cured film is formed under a relatively thick film even in the presence of a light stabilizer such as an ultraviolet absorber. Formation is possible. The UV-curable coating material produced by a method other than the present invention has insufficient curability, and when a thick film is formed, appearance defects such as a decrease in transparency and occurrence of cracks are liable to occur. There is a problem in durability and weather resistance.
[0019]
The coating material composition using the ultraviolet-curable coating material of the present invention not only has excellent curability, but also has excellent abrasion resistance, durability, and weather resistance of the cured film.
[0020]
The solid content concentration in the condensation reaction, that is, the total amount of the solid content of component (a-2) (converted as silanol) and the solid content of component (a-1) is in the range of 30 to 90% by weight. If the solid content is less than 30% by weight, that is, if the amount of the nonpolar solvent exceeds 70% by weight, the reaction may be insufficient and the transparency of the cured film under the thick film may be poor. Conversely, if the solid content exceeds 90% by weight, a rapid reaction may occur, which causes problems such as gel formation.
[0021]
The temperature in the condensation reaction is preferably in the range of 60 to 150 ° C. When the reaction temperature is lower than 60 ° C., the reaction may be insufficient and the reaction requires a long time. Conversely, when the reaction temperature exceeds 150 ° C., a reaction other than condensation of silicon occurs, or a problem such as formation of a gel occurs.
[0022]
The ratio of the solid content of the component (a-1) to the solid content of the component (a-2) (converted as silanol) in the condensation reaction is (a-1) / (a-2) = 40 to 90 / It is 60 to 10% by weight (total 100% by weight), preferably 50 to 80/50 to 20% by weight. When the use ratio is out of the above range, for example, if the component (a-1) exceeds 90% by weight, the reaction system becomes cloudy or a problem such as formation of a gel occurs, and conversely, less than 40% by weight. In such a case, the reaction may be insufficient, and when the film is formed thick, the transparency of the cured film may decrease. On the other hand, when the component (a-1) exceeds 90% by weight, cracks tend to occur in the cured film, and when it is less than 40% by weight, the abrasion resistance and transparency of the cured film deteriorate.
[0023]
Next, the coating composition of the present invention will be described.
[0024]
(A) About the component
The ultraviolet curable coating material as the component (A) is obtained by the above-described production method, and is a component that improves the wear resistance, weather resistance, and durability of the cured film. The use ratio (solid content) of the component (A) is 5 to 50 parts by weight, preferably 10 to 40 parts by weight, per 100 parts by weight of the coating material composition comprising the components (A) and (B). When the use ratio of the component (A) is less than 5 parts by weight in the coating composition, a sufficient effect of improving abrasion resistance, weather resistance and durability cannot be obtained. Cracks are observed in the coating.
[0025]
About component (B)
The polyfunctional monomer or monomer mixture having two or more (meth) acryloyloxy groups in one molecule, which is the component (B), is capable of improving the toughness and adhesion of the cured film without deteriorating the abrasion resistance. It is a component that improves the properties. The cured film formed only from the component (A) has excellent abrasion resistance but does not have sufficient adhesion, and is liable to cracks and the like, and it is difficult to form a practical cured film.
[0026]
Specific examples of the component (B) include bis (2-acryloxyethyl) -hydroxyethyl-isocyanurate, 1,6-hexanediol diacrylate, 1,4-butanediol diacrylate, and 1,9-nonanediol diacrylate. Bifunctional monomers such as acrylate, neopentyl glycol diacrylate, neopentyl glycol diacrylate hydroxypivalate, and urethane acrylate; trimethylolpropane triacrylate, pentaerythritol triacrylate, tris (acryloxyethyl) isocyanurate, ditrimethylol Propane tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, urethane acrylate, polyhydric alcohol and polybasic acid, and (meth) acryl Ester compound synthesized from, for example, polyfunctional monomers such as trifunctional or more ester compounds synthesized from trimethylolethane / succinic acid / acrylic acid = 2/1/4 mol, and the like. In addition, UV. Examples described in EB Curing Handbook-Raw Materials (Polymer Publishing Association) can be given.
[0027]
Among these polyfunctional monomers, bis (2-acryloxyethyl) -hydroxyethyl isocyanurate and tris (acryloxyethyl) isocyanurate have a large effect of improving the toughness, weather resistance and durability of the cured film. Particularly preferred. Further, a monomer mixture in which three kinds of 1,9-nonanediol diacrylate are used in combination with both polyfunctional monomers is particularly preferable because of excellent weather resistance, durability and adhesion to a substrate.
[0028]
Component (B) is used in an amount of 95 to 50 parts by weight, preferably 90 to 60 parts by weight, per 100 parts by weight of the coating composition comprising the components (A) and (B). If the use ratio of the component (B) is less than 50 parts by weight in the coating material composition, a cured film having sufficient toughness, adhesion, heat resistance and weather resistance cannot be obtained. Abrasion resistance decreases.
[0029]
About component (C)
The coating composition of the present invention contains a photopolymerization initiator (C) component. Specific examples of the component (C) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, acetoin, butyroin, toluoin, benzyl, benzophenone, p-methoxybenzophenone, diethoxyacetophenone, α, α -Dimethoxy-α-phenylacetophenone, methylphenylglyoxylate, ethylphenylglyoxylate, 4,4-bis (dimethylaminobenzophenone), 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- Carbonyl compounds such as hydroxycyclohexyl phenyl ketone and 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one; tetramethylthiuram disulfide and the like Yellow compounds; Azo compounds such as azobisisobutyronitrile and azobis-2,4-dimethylvaleronitrile; Peroxide compounds such as benzoyl peroxide and ditertiary butyl peroxide; 2,4,6-trimethylbenzoyldiphenylphosphine oxide Phosphine oxide compounds of the formula (1).
[0030]
Among the photopolymerization initiator (C) components, it is preferable to use 2,4,6-trimethylbenzoyldiphenylphosphine oxide in combination with another photopolymerization initiator in terms of weather resistance and durability.
[0031]
Component (C) is used in an amount of 0.01 to 5 parts by weight, preferably 0.1 to 3 parts by weight, based on 100 parts by weight of the total of components (A) and (B). When the use ratio of the component (C) exceeds 5 parts by weight, coloring and weather resistance of the cured film are reduced.
[0032]
The above are the essential components constituting the coating composition of the present invention, and further, an ultraviolet absorber and a light stabilizer are added to the coating composition of the present invention for the purpose of improving weather resistance and durability. Can be. The ultraviolet absorber to be used is not particularly limited, and any ultraviolet absorbent which can be uniformly dissolved in the coating material composition and has good weather resistance can be used, but has good solubility and weather resistance in the coating material composition. From the viewpoint of the effect of improving the properties, an ultraviolet absorber which is a compound derived from a benzophenone type, a benzotriazole type, a phenyl salicylate type, or a phenyl benzoate type and has a maximum absorption wavelength in a range of 240 to 380 nm is preferable. In particular, a benzophenone-based UV absorber is used because it can be contained in a large amount in the coating material composition, and a benzotriazole-based UV absorber is used because it can prevent yellowing of a substrate such as polycarbonate. Is preferred.
[0033]
Specific examples of the ultraviolet absorber include 2-hydroxybenzophenone, 5-chloro-2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octyloxybenzophenone, -Dodecyloxy-2-hydroxybenzophenone, 2-hydroxy-4-octadecyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, phenyl salicylate, p -Tert. -Butylphenyl salicylate, p- (1,1,3,3-tetramethylbutyl) phenyl salicylate, 3-hydroxyphenylbenzoate, phenylene-1,3-dibenzoate, 2- (2-hydroxy-5-methylphenyl) Benzotriazole, 2- (2-hydroxy-5-tert.-butylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-tert.-butylphenyl) -5-chlorobenzotriazole, 2- ( 2-hydroxy-3,5-di-tert.-butylphenyl) benzotriazole, 2- (2-hydroxy-5-tert.-octylphenyl) benzotriazole, and the like. These may be used in combination of two or more.
[0034]
A hindered amine light stabilizer can be used as the light stabilizer. When the light stabilizer is used in combination with the ultraviolet absorber, the weather resistance of the cured film is further improved. Specific examples of the hindered amine light stabilizer include bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, Bis (1,2,2,6,6-pentamethyl-4-piperidyl) 2- (3,5-di-tert.-butyl-4-hydroxybenzyl) -2-n-butylmalonate and the like can be mentioned. Of these, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate are particularly preferred.
[0035]
The coating composition of the present invention may further comprise an organic solvent, an antioxidant, an anti-yellowing agent, a bluing agent, a pigment, a leveling agent, an antifoaming agent, a thickener, an anti-settling agent, Various additives such as an inhibitor and an anti-fogging agent may be contained.
[0036]
The organic solvent is used by being blended into the coating composition from the viewpoints of uniform solubility of the coating composition, dispersion stability, and even adhesion to the substrate and smoothness of the coating and uniformity. The solvent is not particularly limited as long as it satisfies the above performance. Specific examples thereof include organic solvents such as alcohols, hydrocarbons, halogenated hydrocarbons, ethers, ketones, esters, and polyhydric alcohol derivatives.
[0037]
In order to apply the coating composition of the present invention to a substrate, a method such as brush coating, spray coating, dip coating, spin coating, and curtain coating is used.
[0038]
The coating amount of the coating composition is such that the thickness of the cured film is 3 to 30 μm, preferably 5 to 25 μm, and particularly preferably 8 to 20 μm. If the thickness of the cured film is less than 3 μm, sufficient abrasion resistance cannot be obtained, and if it exceeds 30 μm, the adhesion to the substrate is reduced, and cracks are easily generated in the film.
[0039]
A known method for irradiating active energy rays such as α, β and γ rays is used as a means for curing the coating applied to the substrate, and a means for curing the coating composition of the present invention is an ultraviolet ray. It is preferable to use As a source of ultraviolet rays, an ultraviolet lamp is generally used in terms of practicality and economy, and specific examples include a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon lamp, and a metal halide lamp. The irradiation atmosphere may be air or an inert gas such as nitrogen or argon.
[0040]
After applying the coating composition of the present invention to the surface of the synthetic resin molded article, before curing with ultraviolet radiation energy, for the purpose of improving the adhesion of the cured coating to the substrate, using an infrared or hot air drying oven, Heat treatment at 20 ° C. to 120 ° C. for 1 minute to 60 minutes may be performed.
[0041]
The coating material composition of the present invention can be used for modifying the surface of various synthetic resin molded articles as a base material. For this synthetic resin molded article, there has been a demand for improvement in wear resistance and weather resistance. There are certain various thermoplastic resins and thermosetting resins. Specific examples include polymethyl methacrylate resin, polycarbonate resin, polyester resin, polyethylene resin, ABS resin, acrylonitrile-styrene copolymer resin, polyamide resin, polyarylate resin, polymethacrylimide resin, polyallyl diglycol carbonate resin, and the like. Can be Above all, polymethyl methacrylate resin, polycarbonate resin, polystyrene resin, and polymethacrylimide resin have excellent transparency and strong abrasion resistance improvement requirements, and therefore, it is particularly effective to use them as the base material of the coating composition of the present invention. It is. Further, the synthetic resin molded products include sheet-shaped molded products, film-shaped molded products, various injection molded products, and the like made of these resins.
[0042]
【Example】
The following examples illustrate the invention in more detail. The evaluation in the examples was performed by the following method. The parts in the examples represent parts by weight.
[0043]
1. Wear resistance
(1) Taber abrasion test
A wear test was performed in accordance with ASTM D-1044 under the conditions of a worn wheel CS-10F, a load of 500 g, and a rotation number of 500 cycles. After abrasion, the samples were washed with a neutral detergent and the haze was measured with a haze meter. Abrasion resistance is indicated by (haze value after abrasion-haze value before abrasion).
(2) Steel wool test
# 000 steel wool (Bonstar (registered trademark) manufactured by Nippon Steel Wool Co., Ltd.) 1 cm ² The pad was placed on the surface of a sample held on a reciprocating abrasion tester table, and was worn for 50 cycles under a load of 1,000 g. This sample was washed with a neutral detergent, and the haze value was measured with a haze meter. Abrasion resistance is indicated by (haze value after abrasion-haze value before abrasion).
[0044]
2. Adhesion
Using a razor on the surface of the sample, make a scratch reaching the substrate 11 times at 1.5mm intervals in the vertical and horizontal directions, make 100 squares, and use cellophane tape (width 25mm, manufactured by Nichiban Co., Ltd.). Then, it is crimped and rapidly peeled upward. Evaluation of adhesion
It is shown by the number of remaining stitches / the total number of stitches (100).
[0045]
3. appearance
(1) Transparency
In accordance with ASTM D-1003, the haze is indicated by a haze meter.
(2) Crack
It was visually observed and the following criteria were used.
○… No cracks
△: Some cracks occurred
×: countless cracks occurred
[0046]
4. Hot water test
After being immersed in hot water of 80 ° C. for 2 hours and then taken out of the hot water, the film was left at room temperature for 1 hour, and then visually observed for transparency and cracks of the coating, and further evaluated for adhesion.
[0047]
5. Weather resistance test
Using a sunshine weatherometer (Suga Test Instruments Co., Ltd., WEL-SUN-DC type), an accelerated exposure test was performed for 2,000 hours under a black panel temperature of 63 ° C., rainfall of 12 minutes / 60 minutes, and cycle test conditions. Was. The transparency of the sample after the exposure was indicated by a haze value, the crack of the coating film was visually observed, and the adhesion was evaluated.
[0048]
Example 1
Preparation of UV curable coating (I)
In a 3 liter four-necked flask equipped with a stirring rod, a thermometer and a condenser, iso-propanol silica sol (dispersion medium: iso-propanol, SiO ₂ Concentration: 30% by weight, primary particle diameter: 12 mμ, trade name: IPA-ST, manufactured by Nissan Chemical Industries, Ltd. (hereinafter abbreviated as IPA-ST) (2,000 g) and 3-methacryloxypropyltrimethoxy 382 g of silane (trade name: A-174, manufactured by Nippon Unicar Co., Ltd.) (hereinafter abbreviated as A-174) is added, the temperature is increased while stirring, and the reflux of volatile components is started, and at the same time, 0.001 N 139 g of an aqueous hydrochloric acid solution was gradually added dropwise, and after completion of the addition, hydrolysis was carried out with stirring for 2 hours under reflux. After completion of the hydrolysis, volatile components such as alcohol and water were distilled off from the obtained liquid under normal pressure. When the amount of dehydration reached 70% of the theoretical value, 600 g of toluene was added and azeotropically distilled. . Further, 1,200 g of toluene was added in several portions, and the solvent was completely replaced to obtain a toluene dispersion. The solid content at this time (SiO ₂ The total amount of 600 g and 317 g of A-174 silanol was 917 g). The concentration was about 60% by weight. Next, the temperature of the reaction system was raised, toluene was distilled off, and the reaction was carried out at 110 ° C. for 4 hours when the dehydration amount reached 80% of the theoretical value. In the course of this reaction, toluene was added in several portions to maintain the solid content at about 60% by weight, and the solid content was adjusted. After completion of the reaction, volatile components such as toluene were distilled off under reduced pressure in order to increase the solid content, and the final solid content was 70% by weight. The obtained ultraviolet-curable coating material (hereinafter, referred to as reaction liquid (I)) was a dark brown, Newtonian fluid, transparent and viscous liquid, and had a viscosity of 8,000 centipoise at 25 ° C. Further, the solid content concentration was 71% when calculated from the heating residue (%).
The heating residue (%) is represented by (weight after heating (g) / weight before heating (g)) × 100 (%), and the heating condition is 105 ° C. for 3 hours. In addition, the solid content concentration in the following Examples and Comparative Examples is indicated by heating residue (%).
[0049]
Example 2
Preparation of UV curable coating (II)
Hydrolysis was performed using the composition and reaction conditions of Example 1.
After completion of the hydrolysis, volatile components such as alcohol and water are distilled off from the obtained liquid under normal pressure. When the amount of dehydration reaches 70% of the theoretical value, 600 g of n-butyl acetate is added and azeotropic distillation is performed. Let out. Further, 1200 g of n-butyl acetate was added in several portions, and the solvent was completely replaced to obtain a dispersion of n-butyl acetate. The solid content at this time was about 65% by weight. Next, the temperature of the reaction system was raised, and n-butyl acetate was distilled off. When the dehydration amount reached 80% of the theoretical value, the reaction was performed at 126 ° C. for 3 hours. In the course of this reaction, n-butyl acetate was added in several portions to maintain the solid content at about 65% by weight, and the solid content was adjusted. After completion of the reaction, volatile components such as n-butyl acetate were distilled off under reduced pressure in order to increase the solid content, and the final solid content was about 68% by weight. The obtained ultraviolet-curable coating material (hereinafter referred to as reaction liquid (II)) was a dark orange, Newtonian fluid transparent and viscous liquid, and had a viscosity of about 4,000 centipoise at 25 ° C. . In addition, the solid content concentration was 68% in the heating residue.
[0050]
Example 3
Preparation of UV curable coating material (III)
Hydrolysis was performed using the composition and reaction conditions of Example 1.
After completion of the hydrolysis, volatile components such as alcohol and water are distilled off from the obtained liquid under normal pressure. When the amount of dehydration reaches 70% of the theoretical value, 600 g of methyl isobutyl ketone is added and azeotropic distillation is performed. I let it. Further, 1,200 g of methyl isobutyl ketone was added in several portions, and the solvent was completely replaced to obtain a dispersion of methyl isobutyl ketone. The solid content at this time was about 60% by weight. Next, the temperature of the reaction system was raised, methyl isobutyl ketone was distilled off, and the reaction was carried out at 116 ° C. for 4 hours when the dehydration amount reached 80% of the theoretical value. In the course of this reaction, methyl isobutyl ketone was added in several portions to maintain the solid content at about 60% by weight, and the solid content was adjusted. After the completion of the reaction, volatile components such as methyl isobutyl ketone were distilled off under reduced pressure in order to increase the solid content, and the final solid content was about 69% by weight. The obtained ultraviolet-curable coating material (hereinafter, referred to as reaction liquid (III)) was a dark orange Newtonian fluid transparent and viscous liquid, and had a viscosity at 25 ° C. of about 2,500 centipoise. In addition, the solid content concentration was 69% in the heating residue.
[0051]
Comparative Example 1
Preparation of UV curable coating (IV)
1,000 g of IPA-ST, 191 g of A-174 and 69.5 g of a 0.001 N hydrochloric acid aqueous solution are put into a 2 liter four-necked flask equipped with a stirring rod, a thermometer and a condenser, and stirred at room temperature for 4 hours to add water. Decomposition was performed. After the hydrolysis, this liquid was left at room temperature for 2 days, aged, and then alcohol and water were distilled off under reduced pressure at 40 ° C. in order to adjust the solid concentration. The obtained reaction solution (hereinafter referred to as reaction solution (IV)) was a pale pink transparent liquid, had a viscosity of about 150 centipoise at 25 ° C., and a solid content concentration of 70% as a residue after heating.
[0052]
Comparative Example 2
Preparation of UV curable coating (V)
1,000 g of IPA-ST and 191 g of A-174 were placed in the same four-necked flask used in Comparative Example 1, and stirred at room temperature for 4 hours to carry out hydrolysis. After hydrolysis, the liquid was left to mature at room temperature for 4 days. The obtained reaction solution (hereinafter, referred to as reaction solution (V)) was colorless and transparent, had a viscosity of 5 centipoise at 25 ° C, and a solid content of 37% as a residue after heating.
[0053]
Comparative Example 3
Preparation of UV curable coating (VI)
1,000 g of IPA-ST and 191 g of A-174 were placed in the same four-necked flask used in Comparative Example 1, and the temperature was raised while stirring. Simultaneously with the reflux of the volatile components, 69.5 g of a 0.001 N aqueous hydrochloric acid solution was gradually added dropwise. After the completion of the dropwise addition, hydrolysis was carried out for 2 hours under reflux while stirring was continued. After the completion of the hydrolysis, the obtained liquid was distilled under normal pressure to distill out volatile components such as water and alcohol, and the liquid was distilled until the dehydration amount became 40% of the theoretical value. Subsequently, the remaining volatile components were reacted under reflux (80 to 83 ° C.) for 2 hours while refluxing. The obtained reaction liquid (hereinafter, referred to as reaction liquid (VI)) was a pink transparent liquid, had a viscosity at 25 ° C of 100 centipoise, and a solid content of 66.5% as a residue after heating.
[0054]
Comparative Example 4
Preparation of UV-curable coating material (VII)
Hydrolysis was performed using the composition and reaction conditions of Comparative Example 3.
After completion of the hydrolysis, volatile components such as alcohol and water were distilled off from the obtained liquid under normal pressure, and when the amount of dehydration reached 70% of the theoretical value, 300 g of toluene was added for azeotropic distillation. . Further, 600 g of toluene was added in several portions, and the solvent was completely replaced to obtain a toluene dispersion system. The solid content at this time was about 65% by weight. Next, the temperature of the reaction system was raised, and the reaction was continued at 110 ° C. while distilling off toluene. As a result, the reaction system became highly viscous and finally gelled. At this time, the solid content concentration was 96% as a residue after heating.
[0055]
Comparative Example 5
Preparation of UV curable coating material (VIII)
Hydrolysis was performed in the same manner as in Comparative Example 3 using 300 g of IPA-ST, 57.3 g of A-174 and 12.5 g of a 0.001 N hydrochloric acid aqueous solution.
After completion of the hydrolysis, volatile components such as alcohol and water are distilled off from the obtained liquid under normal pressure. When the dehydration amount reaches 70% of the theoretical value, 200 g of n-butyl acetate is added and azeotropic distillation is performed. Let out. Further, 1500 g of n-butyl acetate was added in several portions, and the solvent was completely replaced to obtain a dispersion of n-butyl acetate. The solid content at this time was about 10% by weight. Next, the temperature of the reaction system was maintained at 90 ° C., and the reaction was performed for 2 hours.
The obtained reaction liquid (hereinafter, referred to as reaction liquid (VIII)) was an orange transparent liquid and had a viscosity of 2.5 centipoise at 25 ° C. Further, the solid content concentration was 13.8% as a residue after heating.
[0056]
Comparative Example 6
Preparation of UV curable coating (IX)
Hydrolysis was performed using the composition and reaction conditions of Comparative Example 3.
After completion of the hydrolysis, volatile components such as alcohol and water are distilled off from the obtained liquid under normal pressure. When the amount of dehydration reaches 70% of the theoretical value, 300 g of ethyl cellosolve is added and azeotropic distillation is performed. Was. Further, 600 g of ethyl cellosolve was added in several portions, and the solvent was completely replaced to obtain a dispersion of ethyl cellosolve. The solid content at this time was about 65% by weight. Next, the temperature of the reaction system was raised, and the reaction was performed at 120 ° C. for 2 hours.
The obtained ultraviolet curable coating material (hereinafter, referred to as reaction liquid (IX)) was an orange transparent liquid and had a viscosity at 25 ° C. of 80 centipoise. In addition, the solid content concentration was 63% in the heating residue.
[0057]
Comparative Example 7
Preparation of UV curable coating (X)
IPA-ST 250g (SiO ₂ The hydrolysis was carried out in the same manner as in Comparative Example 3 using 75 g), 361.2 g of A-174 and 78.6 g of a 0.001 N aqueous hydrochloric acid solution.
After the completion of the hydrolysis, volatile components such as alcohol and water were distilled off under normal pressure, and when the dehydration amount reached 70% of the theoretical value, 300 g of toluene was added to perform azeotropic distillation. Further, 600 g of toluene was added in several portions, and the solvent was completely replaced to obtain a toluene dispersion system. The solid content at this time was about 85% by weight. Next, the reaction system was heated and reacted at 90 ° C. for 4 hours. The obtained ultraviolet-curable coating material (hereinafter, referred to as reaction product (X)) was a light brown transparent liquid and had a viscosity at 25 ° C. of 250 centipoise. In addition, the solid content concentration was 82% as a residue after heating.
[0058]
Example 4
Preparation of UV curable coating (XI)
In the four-necked flask of Example 1, meta-silica sol (dispersion medium; methanol, SiO ₂ A concentration of 30% by weight, a primary particle diameter of 12 μm, a trade name of 2,000 g of methanol silica sol (manufactured by Nissan Chemical Industries, Ltd.) and 382.9 g of A-174 were added, and hydrolysis was carried out according to the method of Example 1. Was.
After completion of the hydrolysis, volatile components such as alcohol and water were distilled off from the obtained liquid under normal pressure. When the amount of dehydration reached 70% of the theoretical value, 600 g of toluene was added and azeotropically distilled. . Further, 1200 g of toluene was added in several portions, and the solvent was completely replaced to obtain a toluene dispersion. At this time, the solid content concentration was about 70% by weight. Next, the temperature of the reaction system was raised, toluene was distilled off, and the reaction was carried out at 85 ° C. for 4 hours when the dehydration amount reached 80% of the theoretical value. In the course of this reaction, toluene was added in several portions to maintain the solid content at about 70%, and the solid content was adjusted. After completion of the reaction, volatile components such as toluene were distilled off under reduced pressure to increase the solid content, and the final solid content was 80% by weight. The obtained ultraviolet curable coating material (hereinafter, referred to as reaction liquid (XI)) was a transparent liquid showing an orange Newtonian fluid, and had a viscosity at 25 ° C of 2,500 centipoise. In addition, the solid content concentration was 82% as a residue after heating.
[0059]
Examples 5 to 12, Comparative Examples 8 to 16
Using the reaction liquids obtained in the above Examples and Comparative Examples, coating compositions having the compositions shown in Table 1 were prepared. Next, the coating material composition was spray-coated on an injection molded plate (100 mm × 100 m × 3 mm (thickness)) of a polycarbonate resin (trade name: Lexan LS-2, color tone 111 clear, manufactured by GE), and room temperature was applied. And then heat-treated at 65 ° C. for 5 minutes in a hot air drier. Then, this was 2,000 mJ / cm using a high pressure mercury lamp (manufactured by Eye Graphic Co., Ltd.) in an air atmosphere. ² Ultraviolet rays having a wavelength of 320 to 380 nm (integrated energy of ultraviolet rays at a wavelength of 320 to 380 nm) were irradiated to obtain an injection molded plate of a polycarbonate resin having a hardened coating having a thickness of 13 μm on its surface. Table 2 shows the obtained evaluation results.
[0060]
Example 11
Using the reaction solution (I) obtained in Example 1, a coating material composition having the composition shown in Table 1 was prepared. Next, this coating material composition is spray-coated on an injection molded plate (100 mm × 100 mm × 3 mm (thickness)) of a methacrylic resin (Acrypet VH, color tone 001, manufactured by Mitsubishi Rayon Co., Ltd.), and left at room temperature for 10 minutes. After that, heat treatment was performed at 60 ° C. for 5 minutes in a hot air dryer. Then, this was 1600 mJ / cm using a high pressure mercury lamp (manufactured by Eye Graphic Co., Ltd.) in an air atmosphere. ² To give an injection molded plate of a methacrylic resin having on its surface a wear-resistant film having a cured film thickness of 12 μm. Table 2 shows the obtained evaluation results.
[0061]
Example 12
Using the reaction solution (I) obtained in Example 1, a coating material composition having the composition shown in Table 1 was prepared. Next, this coating material composition was dip-coated on an injection molded plate (100 mm × 120 mm × 3 mm (thickness)) of a polymethacrylimide resin (P50S05, color tone 003, manufactured by Mitsubishi Rayon Co., Ltd.), and then at room temperature for 5 minutes. After standing, it was heat-treated at 60 ° C. for 5 minutes in a hot-air dryer. Then, this was 2,000 mJ / cm using a high pressure mercury lamp (manufactured by Eye Graphic Co., Ltd.) in an air atmosphere. ² To obtain an injection molded plate of a polymethacrylimide resin having a wear-resistant coating having a cured coating thickness of 10 μm on the surface. Table 2 shows the obtained evaluation results.
The abbreviations in Table 1 represent the following compounds.
[0062]
FA-731A: Tris (acryloxyethyl) isocyanurate (manufactured by Hitachi Chemical Co., Ltd.)
M-215: bis (2-acryloxyethyl) -hydroxyethyl isocyanurate (manufactured by Toa Gosei Chemical Industry Co., Ltd.)
C ₉ -DA: 1,9-nonanediol diacrylylate (trade name: Biscoat # 260, manufactured by Osaka Organic Chemical Industry Co., Ltd.)
Lucirin-TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (manufactured by BASF)
Vicure 55: methylphenyl glyoxide (manufactured by Stouffer)
Tinuvin-PS: 2- (hydroxy-5-t-butylphenyl) benzotriazole (manufactured by Ciba-Geigy)
SANOL LS-770: bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate (manufactured by Sankyo Co., Ltd.)
[0063]
[Table 1]

[0064]
[Table 2]

[0065]
【The invention's effect】
As described above, the ultraviolet-curable coating material obtained by the production method of the present invention and the coating material composition using the same are excellent not only in curability but also in the effect of improving the abrasion resistance of a synthetic resin molded product. It is particularly useful for automotive-related parts with high demands on durability and weather resistance, particularly for applications such as headlight lens covers, tail lamps and side lamps.

Claims (2)

(A-1) 40 to 90% by weight of colloidal silica fine particles (solid content) and (a-2) the following general formula (I)

(Wherein, X is a CH ₂ −CH—COO— group, CH ₂ ＣC (CH ₃ ) —COO— group, or CH ₂ ＣＨCH— group, R ₁ is an alkylene group having 1 to 8 carbon atoms, R ₂ , R ₃ represents an alkyl group having 1 to 8 carbon atoms, a represents a positive integer of 1 to 3, b represents a positive integer of 0 to 2, and a + b represents an integer of 1 to _3. ) With a hydrolyzate (solid content) of 60 to 10% by weight (total 100% by weight) in a polar solvent, and when the amount of dehydration in the reaction becomes 30 to 80% by weight of the theoretical value, the polar solvent Is replaced with a non-polar solvent, and a UV-curable coating material obtained by a condensation reaction in the presence of a solid content of 30 to 90% by weight in the non-polar solvent. (A) 5 to 50 parts by weight of the ultraviolet-curable coating material (solid content) according to claim 1,
(B) 95 to 50 parts by weight of a polyfunctional monomer or monomer mixture having two or more (meth) acryloyloxy groups in one molecule, and (C) 0.01 to 5 parts by weight of a photopolymerization initiator (Based on 100 parts by weight of the total of component (A) and component (B))
A wear-resistant coating material composition comprising: