JP4582936B2 - Sealer anti-slip method and sealer anti-slip agent - Google Patents

Description

【００１９】
［式中、Ｒは、水素原子、メチル基、またはエチル基であり、ｍは２以上の整数であり、ｎはそれぞれ独立して２または３である。］
で示す構造を有するアミノポリエーテルを用いることが好ましい。このアミノポリエーテルは、側鎖にアルキレン鎖を有し、かつそのアルキレン鎖の末端に１級または２級の水酸基を有していることを特徴とする。
【００２０】
ここで、そのポリオキシアルキレン鎖の繰り返し単位数を示すｍの値としては、２〜２０の整数が好ましく、さらには９〜１５の整数が好ましい。このようにｍはポリオキシアルキレン鎖の繰り返し単位数を示すが、そのポリオキシアルキレン鎖中のＲは、通常同一であるが、互いに異なるＲを有するポリオキシアルキレン鎖単位であっても良い。
【００２１】
また、上記の式で、１級アミノ基に結合しているポリメチレン鎖の繰り返し単位数ｎとしては、それぞれ独立に２または３であるが、ともに２がより好ましい。
【００２２】
上記アミノポリエーテルはポリオキシアルキレンケチミンを加水分解して製造され、その具体的製造方法は、特開平1−２４９７４８号公報に記載されている。このアミノポリエーテルの数平均分子量は１５０〜３０００、好ましくは５００〜２０００とされる。
【００２３】
ジエポキシドとしては、ポリオキシアルキレングリコールジグリシジルエーテルとジカルボン酸との反応物が好ましい。そのポリオキシアルキレングリコールジグリシジルエーテルの具体例としては、ポリオキシエチレングリコールジグリシジルエーテル（ポリエチレングリコールのエポキシエーテル）、ポリオキシプロピレングリコールジグリシジルエーテル、ポリオキシイソプロピレングリコールジグリシジルエーテル、ポリオキシブチレングリコールジグリシジルエーテルなどが挙げられる。好ましくは、ポリオキシイソプロピレングリコールジグリシジルエーテルである。
【００２４】
又は、そのポリオキシアルキレングリコールジグリシジルエーテルの分子量としては、３００〜１０００が好ましい。分子量が３００未満であると、電着塗膜の耐衝撃性の低下となり、１０００を超えると、中塗りまたは上塗りとの密着性が不良となる。上記ジエポキシドの分子量は、長鎖のアルキル基を有するジカルボン酸を上記ポリオキシアルキレングリコールジグリシジルエーテルに適量反応させることにより制御できる。このようなジカルボン酸の例としては、１，１０−ドデカンジカルボン酸、アジピン酸等があり、中でもダイマー酸（商品名バーサダイム２１６、ヘンケル白水社製）が好ましい。
【００２５】
ポリオキシアルキレングリコールジグリシジルエーテルと、ジカルボン酸の配合比は、例えば、モル比で１．１／１〜２／１が好ましい。
【００２６】
アミノポリエーテル変性エポキシをカチオン電着塗料組成物に添加する場合には、得られたアミノポリエーテル変性エポキシを中和剤を含むイオン交換水に加えて十分に攪拌してエマルションの形態にすることが好ましい。
【００２７】
ここで、中和剤としては、カチオン電着塗料の製造の際に通常用いられる中和剤であれば、特に制限はなく、具体的には、塩酸、硝酸、燐酸、蟻酸、酢酸、乳酸のような無機酸または有機酸などである。中和剤の使用量は、前記アミノポリエーテル変性エポキシ中のアミノ基を部分的に中和して、水分散できる程度であれば十分である。
【００２８】
このようにして得られる、アミノポリエーテル変性エポキシの安定なエマルションを得るためには、該アミノポリエーテル変性エポキシのアミン価を、固形分１００ｇ当たり３２ｍｅｑ以上であることが好ましい。そのアミン価が、３２ｍｅｑ未満であると、水分散性が低下することになる。
【００２９】
カチオン性エポキシ樹脂
本発明で用いるカチオン性エポキシ樹脂には、アミンで変性されたエポキシ樹脂が含まれる。このカチオン性エポキシ樹脂は、特開昭５４−４９７８号、同昭５６−３４１８６号などに記載されている公知の樹脂でよい。
【００３０】
カチオン性エポキシ樹脂は、典型的には、ビスフェノール型エポキシ樹脂のエポキシ環の全部をカチオン性基を導入し得る活性水素化合物で開環するか、または一部のエポキシ環を他の活性水素化合物で開環し、残りのエポキシ環をカチオン性基を導入し得る活性水素化合物で開環して製造される。
【００３１】
ビスフェノール型エポキシ樹脂の典型例はビスフェノールＡ型またはビスフェノールＦ型エポキシ樹脂である。前者の市販品としてはエピコート８２８（油化シェルエポキシ社製、エポキシ当量１８０〜１９０）、エピコート１００１（同、エポキシ当量４５０〜５００）、エピコート１０１０（同、エポキシ当量３０００〜４０００）などがあり、後者の市販品としてはエピコート８０７、（同、エポキシ当量１７０）などがある。
【００３２】
特開平５−３０６３２７号公報第０００４段落の式、化３に記載のような、オキサゾリドン環含有エポキシ樹脂をカチオン性エポキシ樹脂として用いてもよい。耐熱性及び耐食性に優れた塗膜が得られるからである。
【００３３】
エポキシ樹脂にオキサゾリドン環を導入する方法としては、例えば、メタノールのような低級アルコールでブロックされたブロックポリイソシアネートとポリエポキシドを塩基性触媒の存在下で加熱保温し、副生する低級アルコールを系内より留去することで得られる。
【００３４】
特に好ましいエポキシ樹脂はオキサゾリドン環含有エポキシ樹脂である。耐熱性及び耐食性に優れ、更に耐衝撃性にも優れた塗膜が得られるからである。
【００３５】
二官能エポキシ樹脂とモノアルコールでブロックしたジイソシアネート（すなわち、ビスウレタン）とを反応させるとオキサゾリドン環を含有するエポキシ樹脂が得られることは公知である。このオキサゾリドン環含有エポキシ樹脂の具体例及び製造方法は、例えば、特開２０００−１２８９５９号公報第００１２〜００４７段落に記載されている。
【００３６】
これらのエポキシ樹脂は、ポリエステルポリオール、ポリエーテルポリオール、および単官能性のアルキルフェノールのような適当な樹脂で変性しても良い。
また、エポキシ樹脂はエポキシ基とジオール又はジカルボン酸との反応を利用して鎖延長することができる。
【００３７】
これらのエポキシ樹脂は、開環後０．３〜４．０ｍｅｑ／ｇのアミン当量となるように、より好ましくはそのうちの５〜５０％が１級アミノ基が占めるように活性水素化合物で開環するのが望ましい。
【００３８】
カチオン性基を導入し得る活性水素化合物としては１級アミン、２級アミン、３級アミンの酸塩、スルフィド及び酸混合物がある。
【００３９】
上記活性水素化合物の具体例としては、ブチルアミン、オクチルアミン、ジエチルアミン、ジブチルアミン、メチルブチルアミン、モノエタノールアミン、ジエタノールアミン、Ｎ−メチルエタノールアミン、トリエチルアミン塩酸塩、Ｎ，Ｎ−ジメチルエタノールアミン酢酸塩、ジエチルジスルフィド・酢酸混合物などのほか、アミノエチルエタノールアミンのケチミン、ジエチレントリアミンのジケチミンなどの１級アミンをブロックした２級アミンがある。アミン類は複数のものを併用して用いてもよい。
【００４０】
硬化剤
本発明の硬化剤で使用するポリイソシアネートとは、１分子中にイソシアネート基を２個以上有する化合物をいう。ポリイソシアネートとしては、例えば、脂肪族系、脂環式系、芳香族系および芳香族−脂肪族系等のうちのいずれのものであってもよい。
【００４１】
ポリイソシアネートの具体例には、トリレンジイソシアネート（ＴＤＩ）、ジフェニルメタンジイソシアネート（ＭＤＩ）、ｐ−フェニレンジイソシアネート、及びナフタレンジイソシアネート等のような芳香族ジイソシアネート；ヘキサメチレンジイソシアネート（ＨＤＩ）、２，２，４−トリメチルヘキサンジイソシアネート、及びリジンジイソシアネート等のような炭素数３〜１２の脂肪族ジイソシアネート；１，４−シクロヘキサンジイソシアネート（ＣＤＩ）、イソホロンジイソシアネート（ＩＰＤＩ）、４，４´−ジシクロヘキシルメタンジイソシアネート（水添ＭＤＩ）、メチルシクロヘキサンジイソシアネート、イソプロピリデンジシクロヘキシル−４，４´−ジイソシアネート、及び１，３−ジイソシアナトメチルシクロヘキサン（水添ＸＤＩ）、水添ＴＤＩ、２，５−もしくは２，６−ビス（イソシアナートメチル）−ビシクロ［２．２．１］ヘプタン（ノルボルナンジイソシアネートとも称される。）等のような炭素数５〜１８の脂環式ジイソシアネート；キシリレンジイソシアネート（ＸＤＩ）、及びテトラメチルキシリレンジイソシアネート（ＴＭＸＤＩ）等のような芳香環を有する脂肪族ジイソシアネート；これらのジイソシアネートの変性物（ウレタン化物、カーボジイミド、ウレトジオン、ウレトイミン、ビューレット及び／又はイソシアヌレート変性物）；等があげられる。これらは、単独で、または２種以上併用することができる。
【００４２】
ポリイソシアネートをエチレングリコール、プロピレングリコール、トリメチロールプロパン、ヘキサントリオールなどの多価アルコールとＮＣＯ／ＯＨ比２以上で反応させて得られる付加体ないしプレポリマーも硬化剤として使用してよい。
【００４３】
ポリイソシアネートは、脂肪族ポリイソシアネート又は脂環式ポリイソシアネートであることが好ましい。形成される塗膜が耐候性に優れるからである。
【００４４】
脂肪族ポリイソシアネート又は脂環式ポリイソシアネートの好ましい具体例には、ヘキサメチレンジイソシアネート、水添ＴＤＩ、水添ＭＤＩ、水添ＸＤＩ、ＩＰＤＩ、ノルボルナンジイソシアネート、それらの二量体（ビウレット）、三量体（イソシアヌレート）等が挙げられる。
【００４５】
ブロック剤は、ポリイソシアネート基に付加し、常温では安定であるが解離温度以上に加熱すると遊離のイソシアネート基を再生し得るものである。
【００４６】
ブロック剤としては、低温硬化（１６０℃以下）を望む場合には、ε−カプロラクタム、δ−バレロラクタム、γ−ブチロラクタムおよびβ−プロピオラクタムなどのラクタム系ブロック剤、及びホルムアルドキシム、アセトアルドキシム、アセトキシム、メチルエチルケトオキシム、ジアセチルモノオキシム、シクロヘキサンオキシムなどのオキシム系ブロック剤を使用するのが良い。
【００４７】
カチオン性エポキシ樹脂と硬化剤とを含むバインダーは、一般に、電着塗料組成物の全固形分の２５〜８５重量％、好ましくは４０〜７０重量％を占める量で電着塗料組成物に含有される。
【００４８】
顔料
電着塗料組成物には着色剤として一般に顔料を含有させる。本発明の電着塗料組成物にも通常用いられる顔料を含有させる。かかる顔料の例としては、チタンホワイト、カーボンブラック及びベンガラのような着色顔料、カオリン、タルク、ケイ酸アルミニウム、炭酸カルシウム、マイカ、クレー及びシリカのような体質顔料、リン酸亜鉛、リン酸鉄、リン酸アルミニウム、リン酸カルシウム、亜リン酸亜鉛、シアン化亜鉛、酸化亜鉛、トリポリリン酸アルミニウム、モリブデン酸亜鉛、モリブデン酸アルミニウム、モリブデン酸カルシウム及びリンモリブデン酸アルミニウム、リンモリブデン酸アルミニウム亜鉛のような防錆顔料等が挙げられる。
【００４９】
顔料は、一般に、電着塗料組成物の全固形分の１〜３５重量％、好ましくは１５〜３０重量％を占める量で電着塗料組成物に含有される。
【００５０】
顔料分散ペースト
顔料を電着塗料の成分として用いる場合、一般に顔料を予め高濃度で水性媒体に分散させてペースト状にする。顔料は粉体状であるため、電着塗料組成物で用いる低濃度均一状態に一工程で分散させるのは困難だからである。一般にこのようなペーストを顔料分散ペーストという。
【００５１】
顔料分散ペーストは、顔料を顔料分散樹脂と共に水性媒体中に分散させて調製する。顔料分散樹脂としては、一般に、カチオン性又はノニオン性の低分子量界面活性剤や４級アンモニウム基及び／又は３級スルホニウム基を有する変性エポキシ樹脂等のようなカチオン性重合体を用いる。水性媒体としてはイオン交換水や少量のアルコール類を含む水等を用いる。一般に、顔料分散樹脂は５〜４０重量部、顔料は１０〜３０重量部の固形分比で用いる。
【００５２】
電着塗料組成物
本発明で用いるカチオン電着塗料組成物は、シーラー滑り防止剤、カチオン性エポキシ樹脂、ブロックポリイソシアネート硬化剤、中和剤および顔料分散ペーストを、中和剤を含む水性媒体中に分散させることによって調製される。
【００５３】
具体的には、あらかじめ上記のカチオン性エポキシ樹脂とブロックポリイソシアネート硬化剤とを、所定量配合して均一に混合した後、その混合物を、中和剤を含む水性媒体中に分散させて、カチオン性エポキシ樹脂とブロックポリイソシアネート硬化剤との混合物のエマルション（以下メインエマルションという）を得る。
【００５４】
一方、これらとは別に、シーラー滑り防止剤を、同様の方法によりエマルションにする。次に、メインエマルション、シーラー滑り防止剤エマルション、顔料分散ペーストおよびイオン交換水を所定量配合して混合し、本発明のカチオン電着塗料を得る。
【００５５】
但し、シーラー滑り防止剤、カチオン性エポキシ樹脂、ブロックポリイソシアネート硬化剤のエマルション製造方法は、上記のような方法に限定されることはなく、例えば、上記の３成分を別々にエマルション化してもよいし、３成分すべてを混合した後エマルション化してもよい。
【００５６】
ここで、本発明でのシーラー滑り防止剤の添加量は、カチオン電着塗料組成物中の全樹脂固形分の１〜３０重量％であることが好ましい。その添加量が１重量％未満であると、電着塗膜に十分にシーラー滑り防止性を付与することができない。一方、その添加量が３０重量％を超えると、電着塗膜の耐食性が低下することになる。
【００５７】
上記ブロックポリイソシアネート硬化剤の量は、加熱硬化時において、上記カチオン性エポキシ樹脂中のアミノ基や水酸基等の活性水素含有官能基と反応して良好な硬化塗膜を与えるのに十分な量であればよく、一般的には上記カチオン性エポキシ樹脂の上記ブロックポリイソシアネート硬化剤に対する固形分重量比で表して９０／１０〜５０／５０、好ましくは８０／２０〜６５／３５の範囲である。
【００５８】
なお、上記ブロックポリイソシアネート硬化剤は、シーラー滑り防止剤中の水酸基とも反応することになるが、上記のような量であっても、十分に、この水酸基とも反応しうる量である。
【００５９】
上記顔料分散ペーストは、上記顔料がカチオン電着塗料中の全樹脂固形分重量に対し１〜３５％となるように配合される。
【００６０】
本発明で用いるカチオン電着塗料組成物は、ジラウリン酸ジブチルスズ、ジブチルスズオキサイドのようなスズ化合物や、通常のウレタン開裂触媒を含むことができる。その添加量は、上記ブロックポリイソシアネート硬化剤の０．１〜５．０重量％とすることが好ましい。
【００６１】
また、本発明で用いるカチオン電着塗料組成物は、水混和性有機溶剤、界面活性剤、酸化防止剤、紫外線吸収剤等の常用の塗料用添加剤を含むことができる。
【００６２】
シーラー滑り防止方法
電着塗装を行う場合、被塗物としては導電性のあるものであれば特に限定されず、例えば、鉄板、鋼板、アルミニウム板及びこれらを表面処理したもの、これらの成型物等を挙げることができる。特に、被塗物として自動車ボディを用いると、本発明の効果が有効に発揮される。
【００６３】
電着塗装は、電着浴に、本発明のシーラー滑り防止剤を含む電着塗料組成物を満たし、被塗物を陰極として陽極との間に、通常、５０〜４５０Ｖの電圧を印加して行う。印加電圧が５０Ｖ未満であると電着が不充分となり、４５０Ｖを超えると、消費電力が大きくなり、不経済である。
【００６４】
上記電圧を印加する場合の電着塗料組成物の浴液温度は、通常、１０〜４５℃が好ましい。
【００６５】
電着過程は、（ｉ）電着塗料組成物に被塗物を浸漬する過程、及び（ii）上記被塗物を陰極して、陽極との間に電圧を印加し、被膜を析出させる過程、から構成されることが好ましい。また、電圧を印加する時間は、電着条件によって異なるが、一般には、２〜４分とすることができる。
【００６６】
上述のようにして得られる電着被膜は、電着過程の終了後、そのまま又は水洗した後、１２０〜２６０℃、好ましくは１６０〜２２０℃で、１０〜３０分間焼き付けることにより硬化させて、塗装を完了する。
【００６７】
硬化後の電着塗膜の膜厚は１０〜２５μｍが好ましい。１０μｍ未満であると、防食性が不充分であり、２５μｍを超えると、塗料の浪費につながる。
【００６８】
このようにして電着塗装された被塗物の表面にシーラーを塗布する。被塗物の表面は垂直面であってもよい。シーラーは塩化ビニル系樹脂、可塑剤、充填剤、結合剤、及び溶剤等を公知の方法で配合することにより調製できる。
【００６９】
シーラーは治具を用いて、一定面積かつ一定の膜厚を形成するように塗布する。膜厚は３００μｍ〜１０ｍｍの範囲内で調整する。シーラー塗布後、直ちに被塗物を垂直に立て、１０〜６０分間室温で乾燥させた後、１４０〜１６０℃、好ましくは１５０℃で２０〜３０分間焼きつけることにより硬化させ、シーラー層を形成させる。
【００７０】
シーラー層が形成された被塗物は、目的に応じて必要な中塗り塗装及び／又は上塗り塗装が更に施される。
【００７１】
【発明の効果】
本発明のシーラー滑り防止方法によれば、電着塗装された被塗物の垂直面に塗布されたシーラー層の位置ずれを抑制することができ、シーラー膜厚の不均一や塗膜外観の悪化を防止できる。更に、本発明のシーラー滑り防止方法は、電着塗膜の焼付けが過剰に行われた場合でも有効である。
【００７２】
【実施例】
以下の実施例により本発明を更に詳細に説明するが、本発明はこれらに限定されない。実施例中、「部」および「％」は、ことわりのない限り、重量基準による。「エポキシ当量」「アミン当量」は固形分当りの数値を示す。
【００７３】
製造例１
カチオン性エポキシ樹脂の製造
攪拌機、冷却管、窒素導入管、温度計および滴下漏斗を装備したフラスコに、２，４−／２，６−トリレンジイソシアネート（重量比＝８／２）９２部、メチルイソブチルケトン（以下、ＭＩＢＫという）９５部およびジブチルスズジラウレート０．５部を仕込んだ。その混合物を攪拌しながら、メタノール２１部を添加した。
【００７４】
その反応は、室温から始め、発熱により６０℃まで昇温し、その後３０分間反応を継続した後、エチレングリコールモノ−２−エチルヘキシルエーテル５７部を滴下漏斗により滴下した。更にビスフェノールＡ−プロピレンオキシド５モル付加体（商品名ニューポールＢＰ−５Ｐ、三洋化成社製）４２部を添加した。反応は主に６０〜６５℃の範囲で行い、ＩＲスペクトルの測定において、イソシアネート基に基づく吸収が消失するまで継続した。
【００７５】
次に、ビスフェノールＡとエピクロルヒドリンから既知の方法で合成したエポキシ当量１８８のビスフェノールＡ型エポキシ樹脂（商品名DER−３３１J、ダウケミカル社製）３６５部を、上記の反応混合物に加えて１２５℃まで昇温した。その後、ベンジルジメチルアミン１．０部を添加し、エポキシ当量４１０になるまで１３０℃で反応させた。
【００７６】
続いて、ビスフェノールＡ８７部を加えて１２０℃で反応させ、エポキシ当量１１９０とした。その後、上記反応混合物を冷却し、ジエタノールアミン１１部、Ｎ−エチルエタノールアミン２４部およびアミノエチルエタノールアミンのケチミン化物の７９％ＭＩＢＫ溶液２５部を加え、１１０℃で２時間反応させた。その後、ＭＩＢＫで不揮発分８０％となるまで希釈し、カチオン性エポキシ樹脂（樹脂固形分８０％）を得た。
【００７７】
製造例２
ブロックポリイソシアネート硬化剤の製造
製造例１と同様のフラスコに、２，５−および２，６−ビス（イソシアナトメチル）−ビシクロ[２．２．１]ヘプタン（三井東圧社製、イソシアネート当量１０３）７２３部、ＭＩＢＫ３３３部およびジブチルスズジラウレート０．０１部を仕込んだ。得られた反応混合物を７０℃まで昇温し、その反応混合物が均一に溶解した後、メチルエチルケトオキシム６１０部を２時間かけて滴下した。滴下終了後、反応温度を７０℃に保持したまま、ＩＲスペクトルの測定において、イソシアネート基に基づく吸収が消失するまで反応を継続させて、メチルエチルケトオキシムブロックポリイソシアネート硬化剤を得た。（樹脂固形分８０％）
【００７８】
製造例３
顔料分散用樹脂の製造
攪拌装置、冷却管、窒素導入管および温度計を装備した反応容器に、イソホロンジイソシアネート（以下、ＩＰＤＩという）２２２．０部を入れ、ＭＩＢＫ３９．１部で希釈した後、ジブチルスズラウレート０．２部を加えた。その後、５０℃に昇温した後、２−エチルヘキサノール１３１．５部を攪拌しながら、乾燥窒素雰囲気中で２時間かけて滴下した。適宜、冷却することにより、反応温度を５０℃に維持した。その結果、２−エチルヘキサノールハーフブロック化ＩＰＤＩが得られた。
【００７９】
次いで、エピコート８２８（油化シェルエポキシ社製ビスフェノールＡ型エポキシ樹脂、エポキシ当量１８２〜１９４）３７６．０部、ビスフェノールＡ１１４．０部およびオクチル酸２９．２部を、攪拌装置、冷却管、窒素導入管および温度計を装備した反応容器に仕込んだ。反応混合物を窒素雰囲気中で１３０℃に加熱し、ジメチルベンジルアミン０．１５部を添加して、発熱反応のもと１７０℃で１時間反応させることにより、エポキシ当量６４９のビスフェノールＡ型エポキシ樹脂を得た。
【００８０】
次いで、１４０℃に冷却した後、上記で調製した２−エチルヘキサノールハーフブロック化ＩＰＤＩ３９６．８部を加え、１４０℃に１時間保持して反応させた。次に、エチレングリコールモノブチルエーテル３２３．２部を加えて希釈した後、その反応混合物を１００℃に冷却した。次いで、アミノエチルエタノールアミンのメチルイソブチルモノケチミン化物の７８．３％ＭＩＢＫ溶液１８８．８部を加えた。
【００８１】
この混合物を１１０℃で１時間保温した後、９０℃まで冷却し、イオン交換水３６０．０部を加えて、更に３０分間攪拌を継続することにより、エポキシ樹脂中のケチミン化部分を1級アミノ基に転化した。この混合物から過剰の水とＭＩＢＫを減圧下で除去した後、エチレングリコールモノブチルエーテル５８８．１部で希釈して、１級アミノ基を有する顔料分散用樹脂を得た。（樹脂固形分５０％）
【００８２】
製造例４
顔料分散ペーストの製造
サンドグラインドミルに製造例３で得られた顔料分散用樹脂６０部、カーボンブラック２．０部、カオリン１００．０部、二酸化チタン８０．０部、リンモリブデン酸アルミニウム１８．０部およびイオン交換水２５１部を入れ、粒度１０μｍ以下になるまで分散して、顔料分散ペーストを得た。
【００８３】
実施例１
アミノポリエーテル変性エポキシＡ（シーラー滑り防止剤Ａ）の合成
攪拌機、温度計、還流冷却管、窒素導入管を装備した反応容器に、ケミオールＥＰ−４００Ｐ（三洋化成工業社製のポリプロピレングリコールジグリシジルエーテル、エポキシ当量２９７）１２９．７部及びバーサダイム２１６（ヘンケル白水社製のダイマー酸、酸価１９２）９９．６部とベンジルジメチルアミン０．６部とを更に加え、１６０℃で酸価が０．５以下になるまで反応させ、エポキシ当量２３００であるジエポキシドを得た。次に、この化合物に、アミン価２５５のアミノポリエーテル（三洋化成社製のジエチレントリアミン・プロピレンオキサイド付加物、商品名：ＡＰ−１０，分子量６８４）４５．６部を添加し８０℃で４時間保温し、アミン当量１３７０、分子量１６５００（以下、シーラー滑り防止剤Ａという）を得た。
【００８４】
実施例２〜４
シーラー滑り防止剤Ｂ〜Ｄの製造
成分の配合量を表１に示すように変更すること以外は実施例１と同様にして、シーラー滑り防止剤Ｂ〜Ｄを得た。
【００８５】
【表１】

(a) ケミオールＥＰ−４００Ｐ（三洋化成工業社製のポリプロピレングリコールジグリシジルエーテル、エポキシ当量２９７）
(b) バーサダイム２１６（ヘンケル白水社製のダイマー酸、酸価１９２）
(c) 三洋化成社製のジエチレントリアミン・プロピレンオキサイド付加物
【００８６】
実施例５
（１）電着塗料組成物の製造
実施例１で製造したシーラー滑り防止剤２６１．１部を、５０％乳酸１２．２部およびイオン交換水３７９．１部の混合液に加え十分に攪拌した後、さらにイオン交換水２７９．７部をゆっくりと加え、シーラー滑り防止剤のエマルションを得た。
【００８７】
一方、上記とは別に、製造例１で得られたカチオン性エポキシ樹脂と、製造例２で得られたブロックポリイソシアネート硬化剤とを、固形分配合比７０：３０で均一に混合した。この混合物を、中和率が４３％になるように氷酢酸が加えられたイオン交換水に加えてゆっくり希釈して、エマルションとした。次いで、固形分３６．０％となるように、減圧下でＭＩＢＫを除去した。ここで得られたエマルションをメインエマルションとする。
【００８８】
このメインエマルション１４８８．３部および製造例４で得られた顔料分散ペースト５１１．１部、上記で調整した、シーラー滑り防止剤のエマルション１２２．１部、イオン交換水１８６９．９部およびジブチルスズオキサイド８．６部とを混合して、固形分２０．０部のカチオン電着塗料組成物を得た。電着塗料中の顔料含有量と全樹脂含有量の固形分重量比は１／３であった。
【００８９】
（２）シーラー滑り防止性の評価
得られた電着塗料組成物を、りん酸亜鉛処理鋼鈑に対して、焼付け後の膜厚が２０μｍになるような電圧で電着塗装し、２００℃で６０分間焼付けを行った。この鋼板の塗装面にシーラー（サンスター社製 塩ビシーラー）を、縦１０ｍｍ、横８ｍｍ、厚さ４ｍｍの寸法のシーラー層が２本並ぶように整形塗布し、鋼板を垂直に立てて、３０分間乾燥させた。
【００９０】
その後、鋼板を立てた状態でオーブンに入れ、１５０℃で３０分間焼付けを行った。鋼板をオーブンから取り出し、鋼板を立てる前を基準にして、シーラー層の下端の位置がどれだけ下方にずれたかによって、シーラー滑り防止性を評価した。シーラー層の下端の位置のずれ寸法は、２本のシーラー層についての平均値とし、このずれ寸法が１．５ｍｍ以内の場合はシーラー滑り防止性が良好であり、「○」と評価した。結果は表２に示す。
【００９１】
実施例６〜８
実施例１のシーラー滑り防止剤の代わりに、実施例２〜４のシーラー滑り防止剤をそれぞれ用いること以外は、実施例１と同様の方法で電着塗料組成物を調製し、シーラー滑り防止性を評価した。評価結果は表２に示す。
【００９２】
【表２】

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealer slip prevention method, and more particularly to a method of preventing sealer slip by performing electrodeposition coating using an electrodeposition coating composition containing a specific aminopolyether-modified epoxy as an additive.
[0002]
[Prior art]
Electrodeposition coating can easily and quickly form a uniform coating on the surface of metal materials, so it is widely used as an undercoating for corrosion protection of metal materials with a wide surface to be painted such as automobile bodies. It's being used. And according to the characteristic requested | required of a coating film, various coatings, such as an intermediate coating and a top coat, are normally given on an electrodeposition coating film.
[0003]
For example, when a chipping resistance is required for the coating film, a sealer may be applied on the electrodeposition coating film. The sealer is used for imparting chipping resistance or for rust prevention and waterproofing at the joint portion of the steel plate. The sealer usually contains a vinyl chloride resin, a plasticizer, a filler, a binder, a solvent, and the like, and is in a sol state before curing.
[0004]
The sealer is usually applied to a thickness of about several millimeters, dried for several minutes, and then cured by heating to form a cured sealer layer. However, during the process of forming the sealer layer, that is, from application to curing, the sealer layer is deformed by its own weight, slips on the vertical painted surface, and the application position may shift downward. The phenomenon in which the sealer layer slides along the surface to be coated and shifts its position is called “sealer slip”. Sealer slip is particularly noticeable when the electrodeposition coating is baked excessively.
[0005]
When sealer slip occurs, the thickness of the sealer becomes thinner at the top, the waterproof and rustproofing power decreases, chipping resistance deteriorates, the bottom becomes thick and uneven, and the boundary between the upper and lower ends Since it becomes wavy, the appearance of the coating film also deteriorates.
[0006]
[Problems to be solved by the invention]
The present invention solves the above-described conventional problems, and its object is to prevent sealer slipping during the application, drying, and baking of a sealer layer on the vertical surface of an electrodeposited object. And a sealer anti-slip agent that can be added to an electrodeposition coating composition to suppress sealer slip.
[0007]
[Means for Solving the Invention]
The present invention relates to a method for forming a coating film comprising the steps of: applying an electrodeposition coating to an article; baking an electrodeposition coating; and providing a sealer layer on a vertical surface of the electrodeposited article. In the method of preventing sealer slip when performing the above, the electrodeposition coating is provided as an additive using an electrodeposition coating composition containing the following sealer slip preventive agent, This achieves the above object.
[0008]
Here, the sealer anti-slip agent has a polyalkylene oxide chain and two primary amino groups or secondary amino groups, an amino polyether having a number average molecular weight of 150 to 3000, and two epoxy groups. A diepoxide having a number average molecular weight of 300 to 7000; reacting in an amount such that the primary amino group or secondary amino group of the amino polyether is 1.05 to 1.8 in terms of equivalent ratio with respect to the epoxy group of the diepoxide It is an amino polyether-modified epoxy having a number average molecular weight of 8000 to 100,000,
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Electrodeposition coating is performed by immersing the object to be coated in the electrodeposition coating composition as a cathode and applying a voltage. The electrodeposition coating composition contains various additives such as a binder, a pigment, a solvent, and a corrosion resistance imparting agent in an aqueous medium. A binder contains the cationic resin which has a functional group, and the hardening | curing agent which hardens this.
[0010]
In the present invention, a cationic epoxy resin in which an active hydrogen compound such as an amine is reacted with an epoxy ring of an epoxy resin as a cationic resin, and the epoxy group is opened to introduce a cationic group, and a polyisocyanate is used as a curing agent. A blocked polyisocyanate with blocked isocyanate groups is used.
[0011]
Sealer anti-slip agent
In the sealer anti-slip method of the present invention, the electrodeposition coating composition further contains a specific sealer anti-slip agent as an additive. In the electrodeposition coating composition, the sealer anti-slip agent is dispersed in an aqueous medium together with other components such as a cationic resin.
[0012]
Then, in the subsequent electrodeposition coating and baking process, the sealer anti-slip agent moves to the surface of the electrodeposition coating, and it is considered that the coating is softened to prevent sealer slip.
[0013]
A preferred compound as a sealer anti-slip agent is an amino polyether-modified epoxy having a polyether chain. This is because the polyether chain can impart sufficient flexibility to the cured coating film, and hydroxyl groups derived from amino groups and epoxy resins react with the curing agent, so that the corrosion resistance of the electrodeposition coating film does not decrease.
[0014]
The structure and molecular weight of the aminopolyether-modified epoxy having a polyether chain must be designed so that it functions as a sealer anti-slip agent. For example, the amino polyether-modified epoxy can be prepared by reacting an amino polyether with a diepoxide. Here, amino polyether refers to a polymer compound having a polyalkylene oxide chain (polyether chain) and two primary amino groups or secondary amino groups, and diepoxide is a polymer compound having two epoxy groups. Say. Here, the meanings of the terms “two primary amino groups” or “secondary amino groups” include two primary amino groups, two secondary amino groups, or one primary amino group and one primary amino group. Secondary amino groups are included.
[0015]
When these two polymer compounds are reacted, the blending amount thereof is in the range of 1.05 to 1.8 in terms of equivalent ratio of primary amino group or secondary amino group of aminopolyether to epoxy group of diepoxide. It is necessary to. If this equivalent ratio is less than 1.05, a part of the epoxy groups may remain at the molecular ends of the resulting amino polyether-modified epoxy, and thus gelation occurs due to further increase in the molecular weight. On the other hand, when the equivalent ratio exceeds 1.8, the stability of the coating is lowered due to the formation of low molecular weight compounds and free amines.
[0016]
What is necessary is just to perform the reaction method similarly to a normal amine-epoxy reaction. As the reaction catalyst, dimethylbenzylamine and 2-ethyl-4-methylimidazole can be used. At that time, the number average molecular weight of the amino polyether-modified epoxy is adjusted to 8000 to 100,000, preferably 10,000 to 50,000.
[0017]
As amino polyether, the formula
[0018]
[Chemical 2]

[0019]
[Wherein, R is a hydrogen atom, a methyl group, or an ethyl group, m is an integer of 2 or more, and n is independently 2 or 3. ]
It is preferable to use an amino polyether having a structure represented by This amino polyether is characterized by having an alkylene chain in the side chain and a primary or secondary hydroxyl group at the end of the alkylene chain.
[0020]
Here, the value of m indicating the number of repeating units of the polyoxyalkylene chain is preferably an integer of 2 to 20, and more preferably an integer of 9 to 15. Thus, m represents the number of repeating units of the polyoxyalkylene chain, and R in the polyoxyalkylene chain is usually the same, but may be polyoxyalkylene chain units having different Rs.
[0021]
In the above formula, the number of repeating units n of the polymethylene chain bonded to the primary amino group is independently 2 or 3, but 2 is more preferable.
[0022]
The amino polyether is produced by hydrolyzing polyoxyalkylene ketimine, and its specific production method is described in JP-A-1-249748. The number average molecular weight of this amino polyether is 150 to 3000, preferably 500 to 2000.
[0023]
The diepoxide is preferably a reaction product of polyoxyalkylene glycol diglycidyl ether and dicarboxylic acid. Specific examples of the polyoxyalkylene glycol diglycidyl ether include polyoxyethylene glycol diglycidyl ether (epoxy ether of polyethylene glycol), polyoxypropylene glycol diglycidyl ether, polyoxyisopropylene glycol diglycidyl ether, polyoxybutylene glycol And diglycidyl ether. Polyoxyisopropylene glycol diglycidyl ether is preferable.
[0024]
Or as molecular weight of the polyoxyalkylene glycol diglycidyl ether, 300-1000 are preferable. When the molecular weight is less than 300, the impact resistance of the electrodeposition coating film is lowered, and when it exceeds 1000, the adhesion with the intermediate coating or the top coating becomes poor. The molecular weight of the diepoxide can be controlled by reacting an appropriate amount of a dicarboxylic acid having a long-chain alkyl group with the polyoxyalkylene glycol diglycidyl ether. Examples of such dicarboxylic acids include 1,10-dodecanedicarboxylic acid, adipic acid and the like, and among them, dimer acid (trade name Versadim 216, manufactured by Henkel Hakusui Co., Ltd.) is preferable.
[0025]
The blending ratio of polyoxyalkylene glycol diglycidyl ether and dicarboxylic acid is preferably, for example, 1.1 / 1 to 2/1 in molar ratio.
[0026]
When aminopolyether-modified epoxy is added to a cationic electrodeposition coating composition, the obtained aminopolyether-modified epoxy is added to ion-exchanged water containing a neutralizing agent and sufficiently stirred to form an emulsion. Is preferred.
[0027]
Here, the neutralizing agent is not particularly limited as long as it is a neutralizing agent that is usually used in the production of cationic electrodeposition coatings. Specifically, hydrochloric acid, nitric acid, phosphoric acid, formic acid, acetic acid, lactic acid are used. Such inorganic acid or organic acid. The use amount of the neutralizing agent is sufficient as long as the amino group in the amino polyether-modified epoxy can be partially neutralized and dispersed in water.
[0028]
In order to obtain a stable emulsion of aminopolyether-modified epoxy thus obtained, the amine value of the aminopolyether-modified epoxy is preferably 32 meq or more per 100 g of solid content. When the amine value is less than 32 meq, the water dispersibility is lowered.
[0029]
Cationic epoxy resin
The cationic epoxy resin used in the present invention includes an epoxy resin modified with an amine. The cationic epoxy resin may be a known resin described in JP-A Nos. 54-4978 and 56-34186.
[0030]
Cationic epoxy resins typically open all of the epoxy rings of a bisphenol-type epoxy resin with an active hydrogen compound capable of introducing a cationic group, or some epoxy rings with other active hydrogen compounds. It is produced by opening the ring and opening the remaining epoxy ring with an active hydrogen compound capable of introducing a cationic group.
[0031]
A typical example of the bisphenol type epoxy resin is a bisphenol A type or bisphenol F type epoxy resin. As the former commercial product, there are Epicoat 828 (manufactured by Yuka Shell Epoxy Co., Epoxy Equivalent 180-190), Epicoat 1001 (Same, Epoxy Equivalent 450-500), Epicoat 1010 (Same, Epoxy Equivalent 3000-4000), etc. Examples of the latter commercially available product include Epicoat 807 (same as above, epoxy equivalent 170).
[0032]
An oxazolidone ring-containing epoxy resin as described in the formula of the Japanese Patent Application Laid-Open No. 5-306327, paragraph 0004, Chemical Formula 3, may be used as the cationic epoxy resin. This is because a coating film having excellent heat resistance and corrosion resistance can be obtained.
[0033]
As a method for introducing an oxazolidone ring into an epoxy resin, for example, a block polyisocyanate blocked with a lower alcohol such as methanol and a polyepoxide are heated and kept in the presence of a basic catalyst, and a by-product lower alcohol is introduced from the system. Obtained by distilling off.
[0034]
Particularly preferred epoxy resins are oxazolidone ring-containing epoxy resins. This is because a coating film having excellent heat resistance and corrosion resistance and further excellent impact resistance can be obtained.
[0035]
It is known that an epoxy resin containing an oxazolidone ring can be obtained by reacting a bifunctional epoxy resin with a diisocyanate blocked with a monoalcohol (ie, bisurethane). Specific examples and production methods of this oxazolidone ring-containing epoxy resin are described, for example, in paragraphs 0012 to 0047 of JP-A No. 2000-128959.
[0036]
These epoxy resins may be modified with suitable resins such as polyester polyols, polyether polyols, and monofunctional alkylphenols.
In addition, the epoxy resin can be chain-extended using a reaction between an epoxy group and a diol or dicarboxylic acid.
[0037]
These epoxy resins are ring-opened with an active hydrogen compound so that an amine equivalent of 0.3 to 4.0 meq / g is obtained after ring opening, and more preferably 5 to 50% of them are occupied by primary amino groups. It is desirable to do.
[0038]
Active hydrogen compounds that can introduce a cationic group include primary amines, secondary amines, tertiary amine acid salts, sulfides and acid mixtures.
[0039]
Specific examples of the active hydrogen compound include butylamine, octylamine, diethylamine, dibutylamine, methylbutylamine, monoethanolamine, diethanolamine, N-methylethanolamine, triethylamine hydrochloride, N, N-dimethylethanolamine acetate, diethyl In addition to disulfide / acetic acid mixtures, there are secondary amines blocked with primary amines such as aminoethylethanolamine ketimine and diethylenetriamine diketimine. A plurality of amines may be used in combination.
[0040]
Hardener
The polyisocyanate used in the curing agent of the present invention refers to a compound having two or more isocyanate groups in one molecule. The polyisocyanate may be, for example, any of aliphatic, alicyclic, aromatic and aromatic-aliphatic.
[0041]
Specific examples of polyisocyanates include aromatic diisocyanates such as tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate, and naphthalene diisocyanate; hexamethylene diisocyanate (HDI), 2,2,4- C3-C12 aliphatic diisocyanates such as trimethylhexane diisocyanate and lysine diisocyanate; 1,4-cyclohexane diisocyanate (CDI), isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI) Methylcyclohexane diisocyanate, isopropylidene dicyclohexyl-4,4'-diisocyanate, and 1,3-diisocyanatomethyl cyclohexyl Carbon such as xane (hydrogenated XDI), hydrogenated TDI, 2,5- or 2,6-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane (also referred to as norbornane diisocyanate), etc. Aliphatic diisocyanates having a number of 5 to 18; aliphatic diisocyanates having an aromatic ring such as xylylene diisocyanate (XDI) and tetramethyl xylylene diisocyanate (TMXDI); Uretdione, uretoimine, burette and / or isocyanurate modified product); These may be used alone or in combination of two or more.
[0042]
Adducts or prepolymers obtained by reacting polyisocyanates with polyhydric alcohols such as ethylene glycol, propylene glycol, trimethylolpropane and hexanetriol at an NCO / OH ratio of 2 or more may also be used as curing agents.
[0043]
The polyisocyanate is preferably an aliphatic polyisocyanate or an alicyclic polyisocyanate. This is because the formed coating film is excellent in weather resistance.
[0044]
Preferred specific examples of the aliphatic polyisocyanate or alicyclic polyisocyanate include hexamethylene diisocyanate, hydrogenated TDI, hydrogenated MDI, hydrogenated XDI, IPDI, norbornane diisocyanate, dimer (biuret) and trimer thereof. (Isocyanurate) etc. are mentioned.
[0045]
The blocking agent is added to a polyisocyanate group and is stable at ordinary temperature, but can regenerate a free isocyanate group when heated to a temperature higher than the dissociation temperature.
[0046]
As a blocking agent, when low temperature curing (160 ° C. or lower) is desired, lactam blocking agents such as ε-caprolactam, δ-valerolactam, γ-butyrolactam and β-propiolactam, and formaldoxime, acetoald It is preferable to use an oxime blocking agent such as oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, and cyclohexane oxime.
[0047]
The binder containing the cationic epoxy resin and the curing agent is generally contained in the electrodeposition coating composition in an amount that occupies 25 to 85% by weight, preferably 40 to 70% by weight of the total solid content of the electrodeposition coating composition. The
[0048]
Pigment
The electrodeposition coating composition generally contains a pigment as a colorant. The electrodeposition coating composition of the present invention also contains a commonly used pigment. Examples of such pigments include colored pigments such as titanium white, carbon black and bengara, extender pigments such as kaolin, talc, aluminum silicate, calcium carbonate, mica, clay and silica, zinc phosphate, iron phosphate, Rust preventive pigments such as aluminum phosphate, calcium phosphate, zinc phosphite, zinc cyanide, zinc oxide, aluminum tripolyphosphate, zinc molybdate, aluminum molybdate, calcium molybdate and aluminum phosphomolybdate, aluminum phosphomolybdate Etc.
[0049]
The pigment is generally contained in the electrodeposition coating composition in an amount that occupies 1 to 35% by weight, preferably 15 to 30% by weight of the total solid content of the electrodeposition coating composition.
[0050]
Pigment dispersion paste
When a pigment is used as a component of an electrodeposition paint, generally the pigment is dispersed in an aqueous medium at a high concentration in advance to form a paste. This is because the pigment is in a powder form, and it is difficult to disperse in a single step in a low concentration uniform state used in the electrodeposition coating composition. Such a paste is generally called a pigment dispersion paste.
[0051]
The pigment dispersion paste is prepared by dispersing a pigment together with a pigment dispersion resin in an aqueous medium. As the pigment dispersion resin, a cationic polymer such as a cationic or nonionic low molecular weight surfactant or a modified epoxy resin having a quaternary ammonium group and / or a tertiary sulfonium group is generally used. As the aqueous medium, ion-exchanged water or water containing a small amount of alcohol is used. Generally, the pigment dispersion resin is used at a solid content ratio of 5 to 40 parts by weight, and the pigment is used at a solid content ratio of 10 to 30 parts by weight.
[0052]
Electrodeposition coating composition
The cationic electrodeposition coating composition used in the present invention is prepared by dispersing a sealer anti-slip agent, a cationic epoxy resin, a block polyisocyanate curing agent, a neutralizing agent and a pigment dispersion paste in an aqueous medium containing a neutralizing agent. Prepared.
[0053]
Specifically, the cationic epoxy resin and the block polyisocyanate curing agent described above are blended in a predetermined amount and mixed uniformly, and then the mixture is dispersed in an aqueous medium containing a neutralizing agent. An emulsion (hereinafter referred to as a main emulsion) of a mixture of a functional epoxy resin and a block polyisocyanate curing agent is obtained.
[0054]
On the other hand, apart from these, the sealer anti-slip agent is made into an emulsion by the same method. Next, a predetermined amount of the main emulsion, sealer anti-slip agent emulsion, pigment dispersion paste and ion-exchanged water are blended and mixed to obtain the cationic electrodeposition paint of the present invention.
[0055]
However, the method for producing an emulsion of the sealer anti-slip agent, the cationic epoxy resin, and the block polyisocyanate curing agent is not limited to the above method. For example, the above three components may be separately emulsified. And after mixing all three components, you may emulsify.
[0056]
Here, the addition amount of the sealer anti-slip agent in the present invention is preferably 1 to 30% by weight of the total resin solids in the cationic electrodeposition coating composition. If the amount added is less than 1% by weight, the electrodeposition coating film cannot be provided with sufficient sealer slip resistance. On the other hand, when the addition amount exceeds 30% by weight, the corrosion resistance of the electrodeposition coating film is lowered.
[0057]
The amount of the block polyisocyanate curing agent is an amount sufficient to react with an active hydrogen-containing functional group such as an amino group or a hydroxyl group in the cationic epoxy resin during heat curing to give a good cured coating film. Generally, it is in the range of 90/10 to 50/50, preferably 80/20 to 65/35, expressed as a solid weight ratio of the cationic epoxy resin to the block polyisocyanate curing agent.
[0058]
In addition, although the said block polyisocyanate hardening | curing agent will also react with the hydroxyl group in a sealer anti-slip agent, even if it is the above quantity, it is the quantity which can fully react with this hydroxyl group.
[0059]
The pigment dispersion paste is blended so that the pigment is 1 to 35% based on the total resin solid weight in the cationic electrodeposition coating.
[0060]
The cationic electrodeposition coating composition used in the present invention can contain a tin compound such as dibutyltin dilaurate and dibutyltin oxide, and a usual urethane cleavage catalyst. The addition amount is preferably 0.1 to 5.0% by weight of the block polyisocyanate curing agent.
[0061]
In addition, the cationic electrodeposition coating composition used in the present invention may contain conventional coating additives such as a water-miscible organic solvent, a surfactant, an antioxidant, and an ultraviolet absorber.
[0062]
Sealer slip prevention method
When performing electrodeposition coating, the material to be coated is not particularly limited as long as it is electrically conductive, and examples thereof include iron plates, steel plates, aluminum plates, and those obtained by surface treatment, and molded products thereof. it can. In particular, when an automobile body is used as an object to be coated, the effect of the present invention is effectively exhibited.
[0063]
In electrodeposition coating, an electrodeposition bath is filled with the electrodeposition coating composition containing the sealer anti-slip agent of the present invention, and a voltage of 50 to 450 V is usually applied between the object to be coated and the anode. Do. If the applied voltage is less than 50V, electrodeposition is insufficient, and if it exceeds 450V, the power consumption increases, which is uneconomical.
[0064]
The bath temperature of the electrodeposition coating composition when applying the voltage is usually preferably 10 to 45 ° C.
[0065]
The electrodeposition process includes (i) a process of immersing an object to be coated in an electrodeposition coating composition, and (ii) a process of applying a voltage between the anode and the anode to deposit a film. It is preferable that it is comprised from these. The time for applying the voltage varies depending on the electrodeposition conditions, but can generally be 2 to 4 minutes.
[0066]
The electrodeposition film obtained as described above is cured by baking at 120 to 260 ° C., preferably 160 to 220 ° C. for 10 to 30 minutes after completion of the electrodeposition process, or after washing with water. To complete.
[0067]
As for the film thickness of the electrodeposition coating film after hardening, 10-25 micrometers is preferable. When the thickness is less than 10 μm, the corrosion resistance is insufficient, and when it exceeds 25 μm, the paint is wasted.
[0068]
A sealer is applied to the surface of the object to be electrodeposited in this way. The surface of the object to be coated may be a vertical surface. The sealer can be prepared by blending a vinyl chloride resin, a plasticizer, a filler, a binder, a solvent and the like by a known method.
[0069]
The sealer is applied using a jig so as to form a certain area and a certain film thickness. The film thickness is adjusted within a range of 300 μm to 10 mm. Immediately after the application of the sealer, the object to be coated is erected vertically, dried at room temperature for 10 to 60 minutes, and then cured by baking at 140 to 160 ° C., preferably 150 ° C. for 20 to 30 minutes, to form a sealer layer.
[0070]
The object to be coated on which the sealer layer is formed is further subjected to a necessary intermediate coating and / or top coating depending on the purpose.
[0071]
【The invention's effect】
According to the sealer slip prevention method of the present invention, the position shift of the sealer layer applied to the vertical surface of the electrodeposited object can be suppressed, and the sealer film thickness is uneven and the coating film appearance is deteriorated. Can be prevented. Furthermore, the sealer slip prevention method of the present invention is effective even when the electrodeposition coating film is baked excessively.
[0072]
【Example】
The following examples further illustrate the present invention in detail but are not to be construed to limit the scope thereof. In the examples, “parts” and “%” are based on weight unless otherwise specified. “Epoxy equivalent” and “amine equivalent” represent values per solid content.
[0073]
Production Example 1
Production of cationic epoxy resin
In a flask equipped with a stirrer, a condenser tube, a nitrogen inlet tube, a thermometer and a dropping funnel, 92 parts of 2,4- / 2,6-tolylene diisocyanate (weight ratio = 8/2), methyl isobutyl ketone (hereinafter, MIBK) 95 parts) and 0.5 part of dibutyltin dilaurate were charged. While stirring the mixture, 21 parts of methanol was added.
[0074]
The reaction started from room temperature, heated to 60 ° C. by exotherm, and then continued for 30 minutes, and then 57 parts of ethylene glycol mono-2-ethylhexyl ether was added dropwise through a dropping funnel. Further, 42 parts of a bisphenol A-propylene oxide 5-mole adduct (trade name Newpol BP-5P, manufactured by Sanyo Chemical Co., Ltd.) was added. The reaction was mainly carried out in the range of 60 to 65 ° C. and continued until the absorption based on the isocyanate group disappeared in the measurement of IR spectrum.
[0075]
Next, 365 parts of an epoxy equivalent 188 bisphenol A type epoxy resin (trade name DER-331J, manufactured by Dow Chemical Co., Ltd.) synthesized from bisphenol A and epichlorohydrin by a known method is added to the above reaction mixture and heated to 125 ° C. Warm up. Thereafter, 1.0 part of benzyldimethylamine was added and reacted at 130 ° C. until the epoxy equivalent was 410.
[0076]
Subsequently, 87 parts of bisphenol A was added and reacted at 120 ° C. to give an epoxy equivalent of 1190. Thereafter, the reaction mixture was cooled, 11 parts of diethanolamine, 24 parts of N-ethylethanolamine and 25 parts of 79% MIBK solution of ketimine of aminoethylethanolamine were added and reacted at 110 ° C. for 2 hours. Then, it diluted with MIBK until it became 80% of non volatile matters, and obtained the cationic epoxy resin (resin solid content 80%).
[0077]
Production Example 2
Production of block polyisocyanate curing agents
In the same flask as in Production Example 1, 723 parts of 2,5- and 2,6-bis (isocyanatomethyl) -bicyclo [2.2.1] heptane (Mitsui Toatsu Co., Ltd., isocyanate equivalent 103), 333 parts of MIBK And 0.01 part of dibutyltin dilaurate was charged. The obtained reaction mixture was heated to 70 ° C., and the reaction mixture was uniformly dissolved. Then, 610 parts of methyl ethyl ketoxime was added dropwise over 2 hours. After completion of the dropping, while maintaining the reaction temperature at 70 ° C., the reaction was continued until the absorption based on the isocyanate group disappeared in the IR spectrum measurement to obtain a methyl ethyl ketoxime block polyisocyanate curing agent. (Resin solid content 80%)
[0078]
Production Example 3
Manufacture of pigment dispersion resin
In a reaction vessel equipped with a stirrer, a cooling tube, a nitrogen introduction tube and a thermometer, 222.0 parts of isophorone diisocyanate (hereinafter referred to as IPDI) was added, diluted with 39.1 parts of MIBK, and then 0.2 parts of dibutyltin laurate. Was added. Thereafter, the temperature was raised to 50 ° C., and then 131.5 parts of 2-ethylhexanol was added dropwise over 2 hours in a dry nitrogen atmosphere while stirring. The reaction temperature was maintained at 50 ° C. by cooling appropriately. As a result, 2-ethylhexanol half-blocked IPDI was obtained.
[0079]
Subsequently, 376.0 parts of Epicoat 828 (bisphenol A type epoxy resin manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 182-194), 114.0 parts of bisphenol A, and 29.2 parts of octyl acid were added to a stirrer, a cooling tube, and nitrogen introduced. A reaction vessel equipped with a tube and a thermometer was charged. The reaction mixture was heated to 130 ° C. in a nitrogen atmosphere, 0.15 part of dimethylbenzylamine was added, and the mixture was reacted at 170 ° C. for 1 hour under an exothermic reaction, whereby a bisphenol A type epoxy resin having an epoxy equivalent of 649 was obtained. Obtained.
[0080]
Subsequently, after cooling to 140 ° C., 396.8 parts of 2-ethylhexanol half-blocked IPDI prepared above was added, and the mixture was allowed to react at 140 ° C. for 1 hour. Next, 323.2 parts of ethylene glycol monobutyl ether was added for dilution, and the reaction mixture was cooled to 100 ° C. Then, 188.8 parts of a 78.3% MIBK solution of aminoethylethanolamine in methyl isobutyl monoketimine was added.
[0081]
The mixture was kept at 110 ° C. for 1 hour, then cooled to 90 ° C., 360.0 parts of ion-exchanged water was added, and stirring was continued for another 30 minutes, whereby the ketiminate portion in the epoxy resin was converted into a primary amino acid. Converted into a group. Excess water and MIBK were removed from this mixture under reduced pressure, and then diluted with 588.1 parts of ethylene glycol monobutyl ether to obtain a pigment dispersing resin having a primary amino group. (Resin solid content 50%)
[0082]
Production Example 4
Manufacture of pigment dispersion paste
60 parts of pigment dispersing resin obtained in Production Example 3, 2.0 parts of carbon black, 100.0 parts of kaolin, 80.0 parts of titanium dioxide, 18.0 parts of aluminum phosphomolybdate and ion-exchanged water in a sand grind mill 251 parts were added and dispersed until the particle size became 10 μm or less to obtain a pigment dispersion paste.
[0083]
Example 1
Synthesis of amino polyether-modified epoxy A (sealer anti-slip agent A)
In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube, 129.7 parts of Chemiol EP-400P (polypropylene glycol diglycidyl ether, epoxy equivalent 297 manufactured by Sanyo Chemical Industries, Ltd.) and Versadim 216 (Henkel white water) A dimer acid made by the company, acid value 192) 99.6 parts and 0.6 part of benzyldimethylamine were further added and reacted at 160 ° C. until the acid value was 0.5 or less, and a diepoxide having an epoxy equivalent of 2300 was obtained. Obtained. Next, 45.6 parts of an aminopolyether having an amine value of 255 (diethylenetriamine / propylene oxide adduct, product name: AP-10, molecular weight 684, manufactured by Sanyo Chemical Co., Ltd.) was added to this compound, and the mixture was kept at 80 ° C. for 4 hours. As a result, an amine equivalent of 1370 and a molecular weight of 16500 (hereinafter referred to as sealer anti-slip agent A) were obtained.
[0084]
Examples 2-4
Manufacture of sealer anti-slip agents BD
Sealer anti-slip agents B to D were obtained in the same manner as in Example 1 except that the compounding amounts of the components were changed as shown in Table 1.
[0085]
[Table 1]

(a) Chemiol EP-400P (polypropylene glycol diglycidyl ether, epoxy equivalent 297 manufactured by Sanyo Chemical Industries)
(b) Versadim 216 (Dimer acid manufactured by Henkel Hakusui Co., acid value 192)
(c) Diethylenetriamine / propylene oxide adduct produced by Sanyo Chemical
[0086]
Example 5
(1) Production of electrodeposition coating composition
261.1 parts of the sealer anti-slip agent produced in Example 1 was added to a mixed solution of 12.2 parts of 50% lactic acid and 379.1 parts of ion-exchanged water, and after sufficient stirring, 279.7 parts of ion-exchanged water was further added. Was slowly added to obtain an emulsion of a sealer anti-slip agent.
[0087]
On the other hand, separately from the above, the cationic epoxy resin obtained in Production Example 1 and the block polyisocyanate curing agent obtained in Production Example 2 were uniformly mixed at a solid content blending ratio of 70:30. This mixture was slowly diluted with ion-exchanged water to which glacial acetic acid had been added so that the neutralization rate was 43% to obtain an emulsion. Next, MIBK was removed under reduced pressure so that the solid content was 36.0%. Let the emulsion obtained here be a main emulsion.
[0088]
1488.3 parts of this main emulsion and 511.1 parts of pigment dispersion paste obtained in Production Example 4, 122.1 parts of sealer anti-slip emulsion prepared above, 1869.9 parts of ion-exchanged water, and dibutyltin oxide 8 .6 parts was mixed to obtain a cationic electrodeposition coating composition having a solid content of 20.0 parts. The solid content weight ratio of the pigment content and the total resin content in the electrodeposition paint was 1/3.
[0089]
(2) Evaluation of sealer slip resistance
The obtained electrodeposition coating composition was electrodeposited on a zinc phosphate-treated steel sheet at a voltage such that the film thickness after baking was 20 μm, and baked at 200 ° C. for 60 minutes. Apply a sealer (PVC sealer made by Sunstar Co., Ltd.) on the coated surface of this steel plate so that two sealer layers with dimensions of 10 mm in length, 8 mm in width, and 4 mm in thickness are aligned, and stand the steel plate vertically for 30 minutes. Dried.
[0090]
Then, it put into the oven in the state which stood the steel plate, and baked for 30 minutes at 150 degreeC. The steel sheet was taken out of the oven, and the sealer slip prevention property was evaluated based on how much the position of the lower end of the sealer layer was shifted downward with reference to the position before the steel sheet was stood. The deviation size of the position of the lower end of the sealer layer was an average value for the two sealer layers. When this deviation size was within 1.5 mm, the sealer slip prevention property was good, and “◯” was evaluated. The results are shown in Table 2.
[0091]
Examples 6-8
An electrodeposition coating composition was prepared in the same manner as in Example 1 except that the sealer anti-slip agent of Examples 2 to 4 was used in place of the sealer anti-slip agent of Example 1, and the sealer anti-slip property was obtained. Evaluated. The evaluation results are shown in Table 2.
[0092]
[Table 2]

Claims (6)

When performing a method of forming a coating film, including: a step of applying an electrodeposition coating to a coating; a step of baking an electrodeposition coating; and a step of forming a sealer layer on a vertical surface of the electrodeposited coating. In the method of preventing sealer slip,
The electrodeposition coating is carried out using an electrodeposition coating composition containing, as an additive, an amino polyether-modified epoxy having the following polyether chain:
An amino polyether having a polyalkylene oxide chain and two primary amino groups or secondary amino groups and having a number average molecular weight of 150 to 3000; having two epoxy groups and having a number average molecular weight of 300 to 7000 Number average molecular weight 8000 obtained by reacting diepoxide with the epoxy group of diepoxide in an amount such that primary amino group or secondary amino group of amino polyether is 1.05 to 1.8 in an equivalent ratio. 100000 amino polyether modified epoxy. The amino polyether has the formula

[Wherein, R is a hydrogen atom, a methyl group, or an ethyl group, m is an integer of 2 or more, and n is independently 2 or 3. ]
The method according to claim 1, which is an amino polyether having a structure represented by:   The method according to claim 1, wherein the diepoxide is obtained by reacting a polyoxyalkylene glycol diglycidyl ether having a molecular weight of 300 to 1,000 with a long-chain alkyl group-containing dicarboxylic acid.   The method according to claim 3, wherein the polyoxyalkylene glycol diglycidyl ether is polyoxyisopropylene glycol diglycidyl ether, and the long-chain alkyl group-containing dicarboxylic acid is a dimer acid.   The method according to claim 1, wherein the content of the aminopolyether-modified epoxy is 1 to 30% by weight in the total resin solid content of the electrodeposition paint. Electrodeposition coating of an electrodeposition coating composition on an object to be coated; baking an electrodeposited film; and providing a sealer layer on a vertical surface of the electrodeposited object to be coated A sealer anti-slip agent used as an additive in an electrodeposition coating composition in a method,
The sealer anti-slip agent, and a polyalkylene oxide chain and two primary amino groups or secondary amino groups, the amino polyethers with a number average molecular weight 150 to 3,000; has two epoxy groups, A diepoxide having a number average molecular weight of 300 to 7000; a primary amino group or a secondary amino group of an amino polyether with respect to the epoxy group of the diepoxide in an equivalent ratio (amino group equivalent to epoxy equivalent) of 1.05 to 1.8 obtained by reacting in an amount of, composed of amino-polyether-modified epoxy having a number average molecular weight from 8,000 to 100,000,
Sealer anti-slip agent.