JP3883831B2 - Surface-treated steel sheet with excellent white rust resistance and method for producing the same - Google Patents

Description

【００１１】
式中、ベンゼン環に結合しているＹ₁およびＹ₂は、それぞれ互いに独立に水素、又は下記一般式（II）、又は（III）により表されるＺ基であり、１ベンゼン環当たりのＺ基の置換数の平均値は０．２〜１．０である。ｎは２〜５０の整数を表す。
【００１２】
【化８】

【００１３】
【化９】

【００１４】
式（II）および（III）中、Ｒ₁、Ｒ₂、Ｒ₃、Ｒ₄およびＲ₅は、それぞれ互いに独立に水素原子、炭素数１〜１０のアルキル基又は炭素数１〜１０のヒドロキシアルキル基を表し、Ａ^-は水酸イオン又は酸イオンを表す。
【００１５】
［２］ 上記［１］の表面処理鋼板において、表面処理剤が、Ｔｉ化合物（Ｄ）を、樹脂化合物（Ａ）とカチオン性ウレタン樹脂（Ｂ）とシランカップリング剤（Ｃ）の合計量の全固形分に対して１〜２０質量％含有することを特徴とする耐白錆性に優れた表面処理鋼板。
【００１６】
［３］ 上記［１］または［２］の表面処理鋼板において、表面処理剤が、リン酸、硝酸及び酢酸、もしくはこれらの塩から選ばれる少なくとも１種の酸化合物（Ｅ）を、樹脂化合物（Ａ）とカチオン性ウレタン樹脂（Ｂ）とシランカップリング剤（Ｃ）の合計量の全固形分に対して１〜３０質量％含有することを特徴とする耐白錆性に優れた表面処理鋼板。
【００１７】
［４］ 上記［１］〜［３］のいずれかの表面処理鋼板において、皮膜厚を０．０１μｍ以上５μｍ未満とした前記表面処理皮膜の上層に、さらに皮膜厚を０．０１μｍ以上５μｍ未満とした有機樹脂皮膜を有し、該有機樹脂皮膜と前記表面処理皮膜の合計の皮膜厚が５μｍ以下であることを特徴とする耐白錆性に優れた表面処理鋼板。
【００１８】
［５］ 亜鉛系めっき鋼板またはアルミニウム系めっき鋼板の表面に、下記一般式（Ｉ）で表される樹脂化合物（Ａ）と、第１〜３アミノ基及び第４アンモニウム塩基から選ばれる少なくとも１種のカチオン性官能基を有するカチオン性ウレタン樹脂（Ｂ）と、活性水素含有アミノ基、エポキシ基、ビニル基、メルカプト基及びメタクリロキシ基から選ばれる少なくとも１種の反応性官能基を有する１種以上のシランカップリング剤（Ｃ）と、Ｔｉ化合物（Ｄ）と、リン酸、硝酸及び酢酸、もしくはこれらの塩から選ばれる少なくとも１種の酸化合物（Ｅ）とを含有し、且つ、カチオン性ウレタン樹脂（Ｂ）及びシランカップリング剤（Ｃ）の含有量が、樹脂化合物（Ａ）とカチオン性ウレタン樹脂（Ｂ）とシランカップリング剤（Ｃ）の合計量の全固形分に対して、それぞれ１〜２０質量％及び４５〜８５質量％である表面処理剤を塗布し、水洗することなく３０℃〜３００℃の到達板温で加熱乾燥し、皮膜厚が０．０１〜５μｍの表面処理皮膜を形成することを特徴とする耐白錆性に優れた表面処理鋼板の製造方法。
【００１９】
【化１０】

【００２０】
式中、ベンゼン環に結合しているＹ₁およびＹ₂は、それぞれ互いに独立に水素、又は下記一般式（II）、又は（III）により表されるＺ基であり、１ベンゼン環当たりのＺ基の置換数の平均値は０．２〜１．０である。ｎは２〜５０の整数を表す。
【００２１】
【化１１】

【００２２】
【化１２】

【００２３】
式（II）および（III）中、Ｒ₁、Ｒ₂、Ｒ₃、Ｒ₄およびＲ₅は、それぞれ互いに独立に水素原子、炭素数１〜１０のアルキル基又は炭素数１〜１０のヒドロキシアルキル基を表し、Ａ^-は水酸イオン又は酸イオンを表す。
【００２４】
［６］ 上記［５］の表面処理鋼板の製造方法において、表面処理剤が、Ｔｉ化合物（Ｄ）を樹脂化合物（Ａ）とカチオン性ウレタン樹脂（Ｂ）とシランカップリング剤（Ｃ）の合計量の全固形分に対して１〜２０質量％含有することを特徴とする耐白錆性に優れた表面処理鋼板の製造方法。
【００２５】
［７］ 上記［５］または［６］の表面処理鋼板の製造方法において、表面処理剤が、リン酸、硝酸及び酢酸、もしくはこれらの塩から選ばれる少なくとも１種の酸化合物（Ｅ）を、樹脂化合物（Ａ）とカチオン性ウレタン樹脂（Ｂ）とシランカップリング剤（Ｃ）の合計量の全固形分に対して１〜３０質量％含有することを特徴とする耐白錆性に優れた表面処理鋼板の製造方法。
【００２６】
［８］ 上記［５］〜［７］のいずれかの表面処理鋼板の製造方法において、前記表面処理皮膜を厚さが０．０１μｍ以上５μｍ未満となるよう形成し、該表面処理皮膜の上層に、該表面処理皮膜との合計皮膜厚が０．０１μｍ以上５μｍ以下となるように、厚さ０．０１μｍ以上５μｍ未満の有機樹脂皮膜をさらに形成することを特徴とする、耐白錆性に優れた表面処理鋼板の製造方法。
【００２７】
【発明の実施の形態】
以下、本発明の詳細とその限定理由を説明する。本発明の表面処理鋼板のベースとなるめっき鋼板としては、亜鉛系めっき鋼板又はアルミニウム系めっき鋼板を用いることができる。亜鉛系めっき鋼板としては、亜鉛めっき鋼板、Ｚｎ−Ｎｉめっき鋼板、Ｚｎ−Ｆｅめっき鋼板（電気めっき、合金化溶融亜鉛めっき）、Ｚｎ−Ｃｒめっき鋼板、Ｚｎ−Ｍｎめっき鋼板、Ｚｎ−Ｃｏめっき鋼板、Ｚｎ−Ｃｏ−Ｃｒ合金めっき鋼板、Ｚｎ−Ｃｒ−Ｎｉめっき鋼板、Ｚｎ−Ｃｒ−Ｆｅめっき鋼板、Ｚｎ−Ａｌ−Ｍｇめっき鋼板（例えばＺｎ−６％Ａｌ−３％Ｍｇ合金めっき鋼板、Ｚｎ−１１％Ａｌ−３％Ｍｇ合金めっき鋼板）、Ｚｎ−Ａｌめっき鋼板（例えば、Ｚｎ−５％Ａｌ合金めっき鋼板、Ｚｎ−５５％Ａｌ合金めっき鋼板）、さらにはこれらのめっきに金属酸化物、ポリマーなどを分散した亜鉛系複合めっき鋼板（例えば、Ｚｎ−ＳｉＯ₂分散めっき鋼板）などを用いることができる。アルミニウム系めっき鋼板としては、アルミニウムめっき鋼板、Ａｌ−Ｓｉめっき鋼板などを用いることができる。
【００２８】
上記のようなめっきのうち、同種または異種のものを２層以上めっきした複層めっき鋼板を用いることができる。また、めっき鋼板としては、鋼板面にあらかじめＮｉなどの薄目付けのめっきを施し、その上に上記のような各種めっきを施したものであってもよい。
【００２９】
めっき方法としては、電解法（水溶液中での電解、非水溶媒中での電解）、溶融法、気相法のうち、実施可能ないずれの方法も採用することができる。
【００３０】
さらに、めっきの黒変を防止することを目的に、めっき皮膜中に１〜２０００ｐｐｍのＮｉ、Ｃｏ、Ｆｅの微量元素を析出させたり、あるいは、めっきの表面にＮｉ、ＣＯ、Ｆｅを含むアルカリもしくは酸性水溶液による表面調整処理を施し、これらの元素を析出させるようにしてもよい。
【００３１】
次に、上記亜鉛系めっき鋼板またはアルミニウム系めっき鋼板の表面に形成される表面処理皮膜およびこの皮膜形成用の表面処理剤組成物について説明する。
【００３２】
本発明の表面処理鋼板において亜鉛系めっき鋼板またはアルミニウム系めっき鋼板の表面に形成される表面処理皮膜は、一般式（Ｉ）で表される樹脂化合物（Ａ）と、第１〜３アミノ基、及び第４アンモニウム塩基から選ばれる少なくとも１種のカチオン性官能基を有するカチオン性ウレタン樹脂（Ｂ）と、活性水素含有アミノ基、エポキシ基、ビニル基、メルカプト基及びメタクリロキシ基から選ばれる少なくとも１種の反応性官能基を有する１種以上のシランカップリング剤（Ｃ）と、Ｔｉ化合物（Ｄ）と、リン酸、硝酸及び酢酸、もしくはこれらの塩から選ばれる少なくとも１種の酸化合物（Ｅ）とを含有する表面処理剤（以下、「本発明の表面処理剤」と言う。）を塗布し、乾燥することにより形成され、所定の膜厚を有する。
【００３３】
本発明の表面処理剤組成物において樹脂化合物（Ａ）は下記一般式（Ｉ）により表される。
【００３４】
【化１３】

【００３５】
式中、ベンゼン環に結合しているＹ₁およびＹ₂は、それぞれ互いに独立に水素、又は下記一般式（II）、又は（III）により表されるＺ基であり、１ベンゼン環当たりのＺ基の置換数の平均値は０．２〜１．０である。ｎは平均重合度を表し、２〜５０の整数である。
【００３６】
ここで、Ｚ基の置換数の平均値とは、全Ｚ基導入数を全ベンゼン環数（即ち２ｎ）で除した数値のことである。また、平均重合度ｎが２未満では耐食性付与効果が不十分となり、一方５０を超えると水溶性の低下、増粘などにより、処理剤中での安定性が低下し、保存安定性が不十分となる。
【００３７】
【化１４】

【００３８】
【化１５】

【００３９】
式（II）および（III）中、Ｒ₁、Ｒ₂、Ｒ₃、Ｒ₄およびＲ₅は、それぞれ互いに独立に水素原子、炭素数１〜１０のアルキル基又は炭素数１〜１０のヒドロキシアルキル基を表す。アルキル基又はヒドロキシアルキル基の炭素数が１０を超えると樹脂（Ａ）を十分に水溶化することができず、処理在中で不安定となり適用できない。Ｒ₁、Ｒ₂、Ｒ₃、Ｒ₄およびＲ₅の具体例としては、メチル、エチル、プロピル、ブチル、ヒドロキシエチル、２−ヒドロキシプロピル、ヒドロキシイソブチルなどを挙げることができる。
【００４０】
Ａ^-は水酸イオン又は酸イオンを表す。酸イオンの具体例としては、硫酸イオン、硝酸イオン、酢酸イオンなどを挙げることができる。
【００４１】
一般式（Ｉ）で表される樹脂（Ａ）はビスフェノール−ホルマリン縮合物で、その合成方法は限定されるものではないが、例えば、アルカリ触媒存在下、ビスフェノールＡにホルマリンとアミンを作用させることにより得ることができる。
【００４２】
本発明における表面処理剤組成物中のカチオン性ウレタン樹脂（Ｂ）は、カチオン性官能基として第１〜３アミノ基、及び第４アンモニウム塩基から選ばれる少なくとも１種のカチオン性官能基を有するものであれば、構成されるモノマー成分であるポリオール、イソシアネート成分および重合方法を特に限定されるものではない。カチオン性官能基としては、例えば、アミノ基、メチルアミノ基、エチルアミノ基、ジメチルアミノ基、ジエチルアミノ基、トリメチルアミノ基、トリエチルアミノ基などが挙げられるが、第１〜３アミノ基、又は第４アンモニウム塩基であれば本発明の性能を損なわない限り限定しない。
【００４３】
本発明の表面処理剤は、カチオン性ウレタン樹脂（Ｂ）を、樹脂化合物（Ａ）とカチオン性ウレタン樹脂（Ｂ）とシランカップリング剤（Ｃ）の合計量の全固形分に対して１〜２０質量％含有する。好ましくは３〜１５質量％、さらに好ましくは４〜１０質量％である。このカチオン性ウレタン樹脂を１〜２０質量％含有することにより、未添加の場合に発生しやすい、腐食初期のごく薄い白錆を効果的に防ぐことができる。この理由は必ずしも明らかではないが、カチオン性ウレタン樹脂を特定比率で配合することにより造膜性が向上し、腐食初期のごく薄い白錆発生を改善することができると考えられる。しかしながら、１質量％未満では初期の薄錆発生の抑制効果が不十分であり、２０質量％を超えると長期の耐食性と耐黒変性が不十分となる。
【００４４】
本発明における表面処理剤組成物中のシランカップリング剤（Ｃ）は、活性水素含有アミノ基、エポキシ基、ビニル基、メルカプト基およびメタクリロキシ基から選ばれる少なくとも１種の反応性官能基を有する１種以上のシランカップリング剤であれば特に限定されるものではないが、具体例を挙げると、Ｎ−（アミノエチル）３−アミノプロピルトリメトキシシラン、３−アミノプロピルトリエトキシシラン、３−グリシドキシプロピルトリメトキシシラン、３−グリシドキシプロピルメチルジメトキシシラン、２−（３，４エポキシシクロヘキシル）エチルトエリメトキシシラン、ビニルトリエトキシシラン、３−メルカプトプロピルトリメトキシシランなどが使用できる。
【００４５】
本発明の表面処理剤は、シランカップリング剤（Ｃ）を、樹脂化合物（Ａ）とカチオン性ウレタン樹脂（Ｂ）とシランカップリング剤（Ｃ）の合計量の全固形分に対して４５〜８５質量％含有する。好ましくは５５〜７５質量、さらに好ましくは６０〜７０質量％である。４５質量％未満では耐食性および塗料密着性が不十分であり、８５質量％を超えると皮膜の耐指紋性が低下する。
【００４６】
本発明における表面処理組剤成物中のＴｉ化合物（Ｄ）は、Ｔｉの供給源となるのもであれば特に対となるアニオンを限定するものではないが、具体例をあげると、酢酸チタン、硝酸チタン、硫酸チタン、リン酸チタン、炭酸チタン、チタンフッ化水素酸などが使用できる。
【００４７】
本発明の表面処理剤は、Ｔｉ化合物（Ｄ）を、樹脂化合物（Ａ）とカチオン性ウレタン樹脂（Ｂ）とシランカップリング剤（Ｃ）の合計量の全固形分に対して１〜２０質量％含有することが好ましい。より好ましくは３〜１５質量％、さらに好ましくは５〜１０質量％である。１質量％未満では耐食性および耐黒変性が不十分であり、２０質量％を超えると表面処理剤の可使時間が短くなり、経済的に不利になる。
【００４８】
本発明における表面処理剤組成物中の酸化合物（Ｅ）は、リン酸、硝酸及び酢酸、もしくはこれらの塩から選ばれる少なくとも１種の酸化合物であれば特に限定するものではないが、具体例を挙げると、オルソリン酸、ピロリン酸、トリメタリン酸、テトラメタリン酸、ヘキサメタリン酸、リン酸二水素アンモニウム、リン酸水素二アンモニウム、リン酸三アンモニウム、リン酸二水素ナトリウム、リン酸水素二ナトリウム、リン酸三ナトリウム、硝酸、硝酸アンモニウム、硝酸ナトリウム、酢酸、酢酸アンモニウム、酢酸ナトリウムなどが使用できる。
【００４９】
本発明の表面処理剤は、リン酸、硝酸及び酢酸、もしくはこれらの塩から選ばれる少なくとも１種の酸化合物（Ｅ）を、樹脂化合物（Ａ）とカチオン性ウレタン樹脂（Ｂ）とシランカップリング剤（Ｃ）の合計量の全固形分に対して１〜３０質量％含有することが好ましい。より好ましくは３〜２０質量％、さらに好ましくは５〜１５質量％である。１質量％未満では耐食性が不十分であり、３０質量％を超えると塗料密着性が不十分である。
【００５０】
また、本発明の表面処理剤は、前記組成物（Ａ）ないし（Ｅ）に加え、充填剤や潤滑剤などを含有し得る。
【００５１】
以上のような本発明表面処理剤組成物により形成される表面処理皮膜は乾燥膜厚が０．０１〜５μｍ、好ましくは０．１〜３μｍ、さらに好ましくは０．３〜２μｍである。乾燥膜厚が０．０１μｍ未満では耐食性が不十分であり、一方、５μｍを超えると導電性や加工性が低下する。
【００５２】
本発明においては、以上述べた表面処理皮膜の上層には、第２層皮膜として有機樹脂皮膜を形成することができる。この場合、第２層である有機樹脂皮膜の皮膜厚を０．０１μｍ以上５μｍ未満にするとともに、第１層皮膜である上記表面処理皮膜の膜厚を０．０１μｍ以上５μｍ未満とし、両皮膜の合計膜厚が５μｍを超えないようにすることが好ましい。より好ましくは、第一層皮膜の上層にさらに第二層有機樹脂皮膜を形成する場合の膜厚は、第一層皮膜の膜厚が０．０１〜２μｍとなるように形成し、さらに第二層有機樹脂皮膜を膜厚０．０１〜３μｍの膜厚とし、合計の膜厚が５μｍを超えないようにする。
【００５３】
亜鉛系めっき鋼板またはアルミニウム系めっき鋼板の表面に上記表面処理皮膜を形成する際には、上述した組成を有する本発明の表面処理剤を乾燥皮膜厚が上記範囲となるようにめっき鋼板に塗布し、水洗することなく加熱乾燥させる。水洗を行わず処理することにより、処理工程を簡略化することができ、さらには排水処理が不要となるので効率及び経済性が向上する。
【００５４】
第二層の有機樹脂皮膜としては、例えば、エポキシ樹脂、ポリヒドロキシポリエーテル樹脂、アクリル系共重合樹脂、エチレン−アクリル酸共重合体樹脂、アルキッド樹脂、ポリブタジエン樹脂、フェノール樹脂、ポリウレタン樹脂、ポリアミン樹脂、ポリフェニレン樹脂類及びこれらの樹脂の２種以上の混合物若しくは付加重合体などが挙げられる。
【００５５】
第二層の皮膜組成物を第一層の表面に順次形成する方法としては、塗布、浸せき、スプレーいずれでもよい。塗布処理方法としては、ロールコーター（３ロール方式、２ロール方式等）、スクイズコーター、ダイコーターなどいずれの方法でもよい。また、スクイズコーター等による塗布処理、あるいは浸せき処理、スプレー処理の後に、エアナイフ法やロール絞り法により塗布量の調整、外観の均一化、膜厚の均一化を行うことも可能である。
【００５６】
本発明の表面処理剤をコーティングした後は、水洗することなく加熱乾燥を行う。加熱乾燥手段としては、ドライヤー、熱風炉、高周波誘導加熱炉、赤外線炉などを用いることができる。加熱処理は、到達板温で３０〜３００℃、好ましくは、４０℃〜２５０℃の範囲で行うことが適当である。この加熱温度が３０℃未満では皮膜中の水分が多量に残り、耐食性が不十分となる。また、３００℃を超えると非経済的であるばかりでなく、皮膜に欠陥が生じ耐食性が低下する。
【００５７】
また、上記のようにして形成された表面処理皮膜の上層に第２層皮膜として有機樹脂皮膜を形成する場合には、第２層皮膜用の処理組成物を上述した膜厚となるように上記表面処理皮膜面に塗布し、乾燥させる。処理組成物の塗布や加熱乾燥は、上述した表面処理の形成に用いた方法に準じて行えばよい。
【００５８】
なお、上述した表面処理皮膜はめっき鋼板の片面、両面のいずれに形成してもよく、めっき鋼板表裏面の皮膜形成の組み合わせとしては、例えば、単層皮膜（表面処理皮膜）／無処理、二層皮膜（表面処理皮膜＋有機樹脂皮膜）／無処理、単層皮膜（表面処理皮膜）／二層皮膜（表面処理皮膜＋有機樹脂皮膜）、二層皮膜（表面処理皮膜＋有機樹脂皮膜）／二層皮膜（表面処理皮膜＋有機樹脂皮膜）など、任意の形態とすることができる。
【００５９】
【実施例】
表面処理剤組成物用の樹脂化合物（Ａ）として表３に示す水分散性樹脂を用い、これにカチオン性ウレタン樹脂（Ｂ）（表４）、シランカップリング剤（Ｃ）（表５）、チタン化合物（Ｄ）（表６）、酸化合物（Ｅ）（表７）を適宜配合し、撹拌機を用いて所要時間撹拌し、表面処理剤組成物を調製した。
【００６０】
冷延鋼板をベースとした家電、建材、自動車部品用の表面処理鋼板である、表２に示すめっき鋼板を処理原板として用いた（表２参照）。なお、鋼板の板厚は、評価の目的に応じて所定の板厚を採用した。このめっき鋼板の表面をアルカリ脱脂処理、水洗乾燥した後、所定の上記表面処理剤組成物をロールコーターにより塗布し、水洗することなく各種温度で加熱乾燥した。皮膜の膜厚は、表面処理組成物の固形分（加熱残分）、または塗布条件（ロールの圧下力、回転速度など）により調整した。得られた表面処理鋼板の皮膜組成、および品質性能（皮膜外観、耐初期薄錆性、耐白錯性、耐黒変性、動電性、耐指紋性、塗料密着性）の各試験を行った結果を表８〜１０に示す。なお、品質性能の評価は、以下のようにして行った。
【００６１】
（１）皮膜外観
各サンプルについて、皮膜外観の均一性（ムラの有り無し）を目視で評価した。評価基準は以下の通りである。
【００６２】
○：ムラが全く無い均一な外観
△：ムラが若干目立つ外観
×：ムラが目立つ外観。
【００６３】
（２）耐初期薄錆性
各サンプルについて、塩水噴霧試験（ＪＩＳ−Ｚ−２３７１）を施し、２４時間経過後の薄錆面積率で評価した。評価基準は以下の通りである。
【００６４】
◎ ：薄錆発生なし
○ ：薄錆面積率２０％未満
○−：薄錆面積率２０％以上、５０％未満
△ ：薄錆面積率５０％以上、８０％未満
× ：薄錆面積率８０％以上。
【００６５】
（３）耐白錆性
各サンプルについて、塩水噴霧試験（ＪＩＳ−Ｚ−２３７１）を施し、１２０時間経過後の白錆面積率で評価した。評価基準は以下の通りである。
【００６６】
◎ ：白錆面積率５％未満
○ ：白錆面積率５％以上、１０％未満
○−：白錆面積率１０％以上、２５％未満
△ ：白錆面積率２５％以上、５０％未満
× ：白錆面積率５０％以上、１００％以下。
【００６７】
（４）耐黒変性
８０℃、９８％ＲＨで２４時間保持前後の色差△Ｌ^＊（ＪＩＳ Ｚ８７２９に規定するＬ^＊ａ^＊ｂ^＊表示系における二つの物体色のＣＩＥ１９７６明度Ｌ^＊の差）の測定を行った。評価基準は以下の通りである。
【００６８】
○ ：△Ｌ^＊＞−１ かつ、ムラがない均一な外観
○−：−２＜ΔＬ^＊≦−１ かつ、ムラがない均一な外観
△ ：△Ｌ^＊≦−２ かつ、ムラがない均一な外観
× ：△Ｌ^＊≦−２ かつ、ムラが目立つ外観。
【００６９】
（５）導電性
ＪＩＳ Ｃ２５５０により層間絶縁抵抗値を測定した。評価基準は以下のと通りである。
【００７０】
○：３Ω・ｃｍ²／枚未満
△：３Ω・ｃｍ²／枚以上、５Ω・ｃｍ²／枚未満
×：５Ω・ｃｍ²／枚以上。
【００７１】
（６）耐指紋性
下記、人工指紋液浸漬前後の色差ΔＥ^＊を下記（Ａ）式にて計算した。
【００７２】
ΔＥ^＊＝｛（△Ｌ^＊）^２＋（△ａ^＊）^２＋（△ｂ^＊）^２｝^１／２・・・（Ａ）
ここで、△Ｌ^＊、△ａ^＊、△Ｌ^＊はＪＩＳ Ｚ８７２９に規定するＬ^＊ａ^＊ｂ^＊表示系における二つの物体色のＣＩＥ１９７６明度Ｌ^＊の差および色座標ａ^＊、ｂ^＊の差である。
【００７３】
【表１】

評価基準は以下の通りである。
【００７４】
◎： △Ｅ≦１
○： １＜△Ｅ≦３
×： △Ｅ＞３
（７）塗料密着性
各サンプルについて、メラミン系の焼き付け塗料（膜厚３０μｍ）を塗装した後、沸水中に２時間浸せきし、直ちに、碁盤目（１０×１０個、１ｍｍ間隔）のカットを入れて接着テープによる貼着、剥離を行い、塗膜の剥離面積率を測定した。評価基準は以下の通りである。
【００７５】
◎：剥離なし
○：剥離面積率５％未満
△：剥離面積率５％以上、２０％未満
×：剥離面積率２０％以上。
【００７６】
【表２】

【００７７】
【表３】

【００７８】
【表４】

【００７９】
【表５】

【００８０】
【表６】

【００８１】
【表７】

【００８２】
【表８】

【００８３】
【表９】

【００８４】
【表１０】

【００８５】
表８〜１０に示した結果から明らかなように、本発明例である実施例１〜１４、同１６〜２０、同２３〜２７、同２９〜４１、同４６〜４９は、皮膜外観、耐初期薄錆性、耐白錆性、耐黒変性、導電性、耐指紋性、及び塗料密着性のいずれにおいても優れていた。これに対し、本発明の表面処理剤の要件を満たさない比較例４２〜４５においては、耐初期薄錆性、耐白錆性、耐黒変性、耐指紋性、及び塗料密着性のすべてを満足するものはなく、いずれかが劣っていた。また、焼付け温度（加熱乾燥温度）が本発明の範囲外である比較例２２及び２８は、耐白錆性が劣っていた。また、表面処理皮膜の膜厚が薄い比較例１５は耐白錆性に劣り、一方膜厚が厚い比較例２１は導電性がかなり劣っていた。
【００８６】
【発明の効果】
本発明により、クロメート処理を施すことなく、耐食性に優れ、更に耐指紋性、耐黒変性および塗装密着性にも優れた優れた表面処理鋼板の提供が可能となった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface-treated steel sheet that is most suitable for use in automobiles, home appliances, and building materials, and particularly relates to an environment-adaptive surface-treated steel sheet that does not contain heavy metals such as chromium at the time of manufacture and products, and a method for manufacturing the same.
[0002]
[Prior art]
Steel plates for home appliances, steel plates for building materials, and steel plates for automobiles have traditionally been made with chromic acid, for the purpose of improving corrosion resistance (white rust resistance, red rust resistance) on the surface of zinc-plated steel sheets or aluminum-based plated steel sheets. Steel plates that have been chromated with a treatment liquid containing dichromic acid or its salts as the main component are widely used. This chromate treatment is an economical treatment method that has excellent corrosion resistance and can be performed relatively easily. is there.
[0003]
Chromate treatment uses hexavalent chromium, a pollution-controlling substance, but this hexavalent chromium is treated in a closed system in the treatment process and is completely reduced, recovered, and not released into nature. In addition, since the elution of chromium from the chromate film can be made almost zero by the sealing action by the organic film, the environment and the human body are not contaminated by hexavalent chromium. However, due to recent global environmental problems, there is an increasing trend to voluntarily reduce the use of heavy metals including hexavalent chromium. In addition, in order not to pollute the environment when the shredder dust of discarded products is dumped, efforts have been made to prevent or reduce heavy metals in the products as much as possible.
[0004]
For this reason, many treatment techniques, so-called chromium-free techniques, have been proposed that do not rely on chromate treatment in order to prevent the occurrence of white rust in zinc-based plated steel sheets. For example, there is a method of forming a thin film by a method such as immersion, coating, or electrolytic treatment using an inorganic compound, an organic compound part, an organic polymer material, or a solution combining these.
[0005]
Specifically, Japanese Patent Application Laid-Open No. 53-121034 discloses a method in which an aqueous solution containing water-dispersible silica, an alkyd resin, and a trialkoxysilane compound is applied to a metal surface and dried to form a coating film. Is disclosed. Further, a surface treatment method for imparting corrosion resistance to a metal material using a water-soluble resin composed of a hydroxypyrone compound derivative, and a metal material using an aqueous solution or a water-dispersible polymer of a hydroxystyrene compound Methods for imparting corrosion resistance are disclosed in JP-A-57-44751 and JP-A-1-177380.
[0006]
However, none of the above-described methods can form a film that imparts high corrosion resistance that can be replaced by a chromate film, and as a matter of fact, the above problems have not yet been solved. Therefore, at present, there is a strong demand for the development of a non-chromium surface treatment agent and treatment method for metal materials having excellent corrosion resistance.
[0007]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems of the prior art, can form a film with excellent corrosion resistance on the surface of a metal material, and further, is a non-chromium metal excellent in fingerprint resistance, blackening resistance and paint adhesion It is an object of the present invention to provide a surface treatment agent for materials and a method for treating a metal material using the same.
[0008]
[Means for Solving the Problems]
As a result of intensive studies by the present inventors in order to solve the above problems, a specific resin compound, a urethane resin having a specific cationic functional group, a silane coupling agent having a specific functional group, and Ti By treating the liquid surface of a metal material with a surface treatment agent containing a compound and a specific acid compound, a film with excellent corrosion resistance can be formed, as well as excellent fingerprint resistance, blackening resistance and paint adhesion. The present inventors have newly found that a coating film can be formed, and have completed the present invention. The present invention has been made based on such findings, and the features thereof are as follows.
[0009]
[1] At least one selected from a resin compound (A) represented by the following general formula (I), a first to third amino group, and a quaternary ammonium base on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet A cationic urethane resin (B) having a cationic functional group and at least one reactive functional group selected from an active hydrogen-containing amino group, an epoxy group, a vinyl group, a mercapto group, and a methacryloxy group A cationic urethane containing a silane coupling agent (C), a Ti compound (D), and at least one acid compound (E) selected from phosphoric acid, nitric acid, and acetic acid, or salts thereof The content of the resin (B) and the silane coupling agent (C) is a combination of the resin compound (A), the cationic urethane resin (B), and the silane coupling agent (C). A surface treatment film having a film thickness of 0.01 μm to 5 μm formed by applying and drying a surface treatment agent of 1 to 20% by mass and 45 to 85% by mass with respect to the total solid content of measurement, respectively. A surface-treated steel sheet excellent in white rust resistance, characterized by having.
[0010]
[Chemical 7]

[0011]
In the formula, Y ₁ and Y ₂ bonded to the benzene ring are each independently hydrogen or a Z group represented by the following general formula (II) or (III), and Z per benzene ring The average number of group substitutions is 0.2 to 1.0. n represents an integer of 2 to 50.
[0012]
[Chemical 8]

[0013]
[Chemical 9]

[0014]
In the formulas (II) and (III), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a hydroxyalkyl having 1 to 10 carbon atoms. Represents a group, and A ⁻ represents a hydroxide ion or an acid ion.
[0015]
[2] In the surface-treated steel sheet according to [1], the surface treatment agent comprises a total amount of the Ti compound (D), the resin compound (A), the cationic urethane resin (B), and the silane coupling agent (C). A surface-treated steel sheet excellent in white rust resistance, characterized by containing 1 to 20% by mass with respect to the total solid content.
[0016]
[3] In the surface-treated steel sheet according to [1] or [2], the surface treatment agent comprises at least one acid compound (E) selected from phosphoric acid, nitric acid and acetic acid, or a salt thereof as a resin compound ( A surface-treated steel sheet excellent in white rust resistance, comprising 1 to 30% by mass based on the total solid content of the total amount of A), cationic urethane resin (B) and silane coupling agent (C) .
[0017]
[4] In the surface-treated steel sheet according to any one of [1] to [3], the film thickness is 0.01 μm or more and less than 5 μm on the upper layer of the surface-treated film having a film thickness of 0.01 μm or more and less than 5 μm. A surface-treated steel sheet excellent in white rust resistance, wherein the total thickness of the organic resin film and the surface treatment film is 5 μm or less.
[0018]
[5] At least one selected from the resin compound (A) represented by the following general formula (I), the first to third amino groups, and the quaternary ammonium base on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet A cationic urethane resin (B) having a cationic functional group and at least one reactive functional group selected from an active hydrogen-containing amino group, an epoxy group, a vinyl group, a mercapto group, and a methacryloxy group A cationic urethane resin containing a silane coupling agent (C), a Ti compound (D), and at least one acid compound (E) selected from phosphoric acid, nitric acid and acetic acid, or salts thereof The content of (B) and the silane coupling agent (C) is the sum of the resin compound (A), the cationic urethane resin (B) and the silane coupling agent (C). Applying a surface treatment agent of 1 to 20% by mass and 45 to 85% by mass, respectively, with respect to the total solid content, heat-dry at an ultimate plate temperature of 30 ° C. to 300 ° C. without washing with water, and coat thickness Forming a surface-treated film having a thickness of 0.01 to 5 μm, a method for producing a surface-treated steel sheet having excellent white rust resistance.
[0019]
[Chemical Formula 10]

[0020]
In the formula, Y ₁ and Y ₂ bonded to the benzene ring are each independently hydrogen or a Z group represented by the following general formula (II) or (III), and Z per benzene ring The average number of group substitutions is 0.2 to 1.0. n represents an integer of 2 to 50.
[0021]
Embedded image

[0022]
Embedded image

[0023]
In the formulas (II) and (III), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a hydroxyalkyl having 1 to 10 carbon atoms. Represents a group, and A ⁻ represents a hydroxide ion or an acid ion.
[0024]
[6] In the method for producing a surface-treated steel sheet according to [5], the surface treatment agent is a total of Ti compound (D), resin compound (A), cationic urethane resin (B), and silane coupling agent (C). The manufacturing method of the surface treatment steel plate excellent in the white rust resistance characterized by containing 1-20 mass% with respect to the total solid of quantity.
[0025]
[7] In the method for producing a surface-treated steel sheet according to [5] or [6], the surface treatment agent comprises at least one acid compound (E) selected from phosphoric acid, nitric acid and acetic acid, or a salt thereof. 1 to 30% by mass of the total solid content of the resin compound (A), the cationic urethane resin (B), and the silane coupling agent (C) is excellent, and the white rust resistance is excellent. Manufacturing method of surface-treated steel sheet.
[0026]
[8] In the method for producing a surface-treated steel sheet according to any one of [5] to [7], the surface-treated film is formed to have a thickness of 0.01 μm or more and less than 5 μm, and is formed on an upper layer of the surface-treated film. Further, an organic resin film having a thickness of 0.01 μm or more and less than 5 μm is further formed so that the total film thickness with the surface treatment film is 0.01 μm or more and 5 μm or less, and has excellent white rust resistance A method for producing a surface-treated steel sheet.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
The details of the present invention and the reasons for limitation will be described below. As the plated steel sheet used as the base of the surface-treated steel sheet of the present invention, a zinc-based plated steel sheet or an aluminum-based plated steel sheet can be used. As zinc-based plated steel sheets, galvanized steel sheets, Zn-Ni plated steel sheets, Zn-Fe plated steel sheets (electroplating, alloyed hot dip galvanizing), Zn-Cr plated steel sheets, Zn-Mn plated steel sheets, Zn-Co plated steel sheets Zn-Co-Cr alloy-plated steel sheet, Zn-Cr-Ni-plated steel sheet, Zn-Cr-Fe-plated steel sheet, Zn-Al-Mg-plated steel sheet (for example, Zn-6% Al-3% Mg alloy-plated steel sheet, Zn- 11% Al-3% Mg alloy-plated steel sheet), Zn-Al-plated steel sheet (for example, Zn-5% Al-alloy plated steel sheet, Zn-55% Al-alloy plated steel sheet), and metal oxides and polymers for these platings A zinc-based composite plated steel sheet (for example, Zn—SiO ₂ dispersion plated steel sheet) in which the above are dispersed can be used. As the aluminum-based plated steel sheet, an aluminum-plated steel sheet, an Al—Si plated steel sheet, or the like can be used.
[0028]
Among the above platings, a multilayer plated steel sheet in which two or more layers of the same type or different types are plated can be used. Moreover, as a plated steel plate, the steel plate surface may be pre-plated with light-weight plating such as Ni and the above-described various plating may be performed thereon.
[0029]
As a plating method, any feasible method among an electrolytic method (electrolysis in an aqueous solution, electrolysis in a non-aqueous solvent), a melting method, and a vapor phase method can be employed.
[0030]
Furthermore, for the purpose of preventing blackening of the plating, 1 to 2000 ppm of trace elements of Ni, Co, Fe are deposited in the plating film, or an alkali containing Ni, CO, Fe on the surface of the plating or You may make it surface-treat with an acidic aqueous solution and precipitate these elements.
[0031]
Next, the surface treatment film formed on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet and the surface treatment agent composition for forming the film will be described.
[0032]
In the surface-treated steel sheet of the present invention, the surface-treated film formed on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet is composed of the resin compound (A) represented by the general formula (I), the first to third amino groups, And a cationic urethane resin (B) having at least one cationic functional group selected from quaternary ammonium bases, and at least one selected from active hydrogen-containing amino groups, epoxy groups, vinyl groups, mercapto groups, and methacryloxy groups One or more silane coupling agents (C) having a reactive functional group, Ti compound (D), and at least one acid compound (E) selected from phosphoric acid, nitric acid and acetic acid, or salts thereof Is formed by applying and drying a surface treatment agent containing the following (hereinafter referred to as “surface treatment agent of the present invention”), and has a predetermined film thickness.
[0033]
In the surface treating agent composition of the present invention, the resin compound (A) is represented by the following general formula (I).
[0034]
Embedded image

[0035]
In the formula, Y ₁ and Y ₂ bonded to the benzene ring are each independently hydrogen or a Z group represented by the following general formula (II) or (III), and Z per benzene ring The average number of group substitutions is 0.2 to 1.0. n represents an average degree of polymerization and is an integer of 2 to 50.
[0036]
Here, the average value of the number of substitution of Z groups is a numerical value obtained by dividing the total number of introduced Z groups by the total number of benzene rings (that is, 2n). Further, if the average degree of polymerization n is less than 2, the effect of imparting corrosion resistance becomes insufficient. On the other hand, if it exceeds 50, the stability in the treatment agent is lowered due to a decrease in water solubility or thickening, and the storage stability is insufficient. It becomes.
[0037]
Embedded image

[0038]
Embedded image

[0039]
In the formulas (II) and (III), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a hydroxyalkyl having 1 to 10 carbon atoms. Represents a group. When the number of carbon atoms of the alkyl group or hydroxyalkyl group exceeds 10, the resin (A) cannot be sufficiently water-solubilized and becomes unstable during treatment and cannot be applied. Specific examples of R ₁ , R ₂ , R ₃ , R ₄ and R ₅ include methyl, ethyl, propyl, butyl, hydroxyethyl, 2-hydroxypropyl, hydroxyisobutyl and the like.
[0040]
A ⁻ represents a hydroxide ion or an acid ion. Specific examples of the acid ion include sulfate ion, nitrate ion, acetate ion and the like.
[0041]
The resin (A) represented by the general formula (I) is a bisphenol-formalin condensate, and its synthesis method is not limited. For example, formalin and amine are allowed to act on bisphenol A in the presence of an alkali catalyst. Can be obtained.
[0042]
The cationic urethane resin (B) in the surface treating agent composition in the present invention has at least one cationic functional group selected from a first to third amino group and a quaternary ammonium base as a cationic functional group. If it is, the polyol which is a monomer component to be constructed, the isocyanate component and the polymerization method are not particularly limited. Examples of the cationic functional group include an amino group, a methylamino group, an ethylamino group, a dimethylamino group, a diethylamino group, a trimethylamino group, and a triethylamino group. If it is an ammonium base, it will not limit unless the performance of this invention is impaired.
[0043]
The surface treating agent of the present invention is a cationic urethane resin (B) 1 to 1 in total solids of the total amount of the resin compound (A), the cationic urethane resin (B) and the silane coupling agent (C). Contains 20% by mass. Preferably it is 3-15 mass%, More preferably, it is 4-10 mass%. By containing 1 to 20% by mass of this cationic urethane resin, it is possible to effectively prevent very thin white rust at the initial stage of corrosion that is likely to occur when not added. The reason for this is not necessarily clear, but it is considered that the formation of a very thin white rust at the beginning of corrosion can be improved by adding a cationic urethane resin in a specific ratio to improve the film-forming property. However, if it is less than 1% by mass, the effect of suppressing the occurrence of initial thin rust is insufficient, and if it exceeds 20% by mass, long-term corrosion resistance and blackening resistance are insufficient.
[0044]
The silane coupling agent (C) in the surface treating agent composition in the present invention has 1 reactive functional group selected from an active hydrogen-containing amino group, an epoxy group, a vinyl group, a mercapto group, and a methacryloxy group. Although it will not specifically limit if it is a silane coupling agent more than a seed | species, If a specific example is given, N- (aminoethyl) 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, 3-glycol will be mentioned. Sidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, vinyltriethoxysilane, 3-mercaptopropyltrimethoxysilane and the like can be used.
[0045]
In the surface treatment agent of the present invention, the silane coupling agent (C) is 45 to 45% of the total solid content of the total amount of the resin compound (A), the cationic urethane resin (B), and the silane coupling agent (C). Contains 85% by mass. Preferably it is 55-75 mass, More preferably, it is 60-70 mass%. If it is less than 45% by mass, the corrosion resistance and paint adhesion are insufficient, and if it exceeds 85% by mass, the fingerprint resistance of the film is lowered.
[0046]
The Ti compound (D) in the surface treatment composition according to the present invention is not particularly limited as long as it is a Ti supply source, but a specific example is titanium acetate. Titanium nitrate, titanium sulfate, titanium phosphate, titanium carbonate, titanium hydrofluoric acid, etc. can be used.
[0047]
In the surface treatment agent of the present invention, the Ti compound (D) is added in an amount of 1 to 20 mass based on the total solid content of the resin compound (A), the cationic urethane resin (B), and the silane coupling agent (C). % Content is preferable. More preferably, it is 3-15 mass%, More preferably, it is 5-10 mass%. If it is less than 1% by mass, corrosion resistance and blackening resistance are insufficient, and if it exceeds 20% by mass, the usable time of the surface treatment agent is shortened, which is economically disadvantageous.
[0048]
The acid compound (E) in the surface treating agent composition in the present invention is not particularly limited as long as it is at least one acid compound selected from phosphoric acid, nitric acid and acetic acid, or salts thereof, but specific examples For example, orthophosphoric acid, pyrophosphoric acid, trimetaphosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, phosphorus Trisodium acid, nitric acid, ammonium nitrate, sodium nitrate, acetic acid, ammonium acetate, sodium acetate and the like can be used.
[0049]
The surface treating agent of the present invention comprises at least one acid compound (E) selected from phosphoric acid, nitric acid and acetic acid, or salts thereof, resin compound (A), cationic urethane resin (B), and silane coupling. It is preferable to contain 1-30 mass% with respect to the total solid of the total amount of an agent (C). More preferably, it is 3-20 mass%, More preferably, it is 5-15 mass%. If it is less than 1% by mass, the corrosion resistance is insufficient, and if it exceeds 30% by mass, the paint adhesion is insufficient.
[0050]
Further, the surface treating agent of the present invention may contain a filler, a lubricant and the like in addition to the compositions (A) to (E).
[0051]
The surface treatment film formed from the surface treatment agent composition of the present invention has a dry film thickness of 0.01 to 5 μm, preferably 0.1 to 3 μm, and more preferably 0.3 to 2 μm. When the dry film thickness is less than 0.01 μm, the corrosion resistance is insufficient. On the other hand, when the dry film thickness exceeds 5 μm, the conductivity and workability deteriorate.
[0052]
In the present invention, an organic resin film can be formed as a second layer film on the surface treatment film described above. In this case, the film thickness of the organic resin film that is the second layer is 0.01 μm or more and less than 5 μm, and the film thickness of the surface treatment film that is the first layer film is 0.01 μm or more and less than 5 μm, It is preferable that the total film thickness does not exceed 5 μm. More preferably, the film thickness when the second layer organic resin film is further formed on the upper layer of the first layer film is formed such that the film thickness of the first layer film is 0.01 to 2 μm, and second The layer organic resin film is made to have a film thickness of 0.01 to 3 μm so that the total film thickness does not exceed 5 μm.
[0053]
When the surface treatment film is formed on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, the surface treatment agent of the present invention having the above-described composition is applied to the plated steel sheet so that the dry film thickness is in the above range. Heat and dry without washing with water. By performing the treatment without rinsing, the treatment process can be simplified, and further, wastewater treatment is not required, so that efficiency and economy are improved.
[0054]
As the organic resin film of the second layer, for example, epoxy resin, polyhydroxy polyether resin, acrylic copolymer resin, ethylene-acrylic acid copolymer resin, alkyd resin, polybutadiene resin, phenol resin, polyurethane resin, polyamine resin , Polyphenylene resins, and mixtures or addition polymers of two or more of these resins.
[0055]
As a method for sequentially forming the coating composition of the second layer on the surface of the first layer, any of coating, dipping, and spraying may be used. As a coating treatment method, any method such as a roll coater (3-roll method, 2-roll method, etc.), a squeeze coater, or a die coater may be used. In addition, after the coating process with a squeeze coater or the like, the immersion process, and the spray process, the coating amount can be adjusted, the appearance can be made uniform, and the film thickness can be made uniform by an air knife method or a roll drawing method.
[0056]
After coating the surface treatment agent of the present invention, drying is performed without washing with water. As the heating and drying means, a dryer, a hot air furnace, a high frequency induction heating furnace, an infrared furnace or the like can be used. It is appropriate to perform the heat treatment in the range of 30 to 300 ° C., preferably 40 to 250 ° C., at the ultimate plate temperature. If this heating temperature is less than 30 ° C., a large amount of moisture remains in the film, resulting in insufficient corrosion resistance. Moreover, when it exceeds 300 degreeC, it will not only be uneconomical but a defect will arise in a membrane | film | coat and corrosion resistance will fall.
[0057]
Further, when an organic resin film is formed as a second layer film on the upper layer of the surface treatment film formed as described above, the treatment composition for the second layer film is formed to have the above-described film thickness. It is applied to the surface treatment film surface and dried. Application | coating and heat drying of a process composition should just be performed according to the method used for formation of the surface treatment mentioned above.
[0058]
The above-mentioned surface treatment film may be formed on either one side or both sides of the plated steel sheet. Examples of combinations of film formation on the front and back surfaces of the plated steel sheet include, for example, a single layer film (surface treatment film) / no treatment, two Layer film (surface treatment film + organic resin film) / No treatment, Single layer film (surface treatment film) / Double layer film (surface treatment film + organic resin film), Double layer film (surface treatment film + organic resin film) / It can be set as arbitrary forms, such as a two-layer film (surface treatment film + organic resin film).
[0059]
【Example】
The water-dispersible resin shown in Table 3 is used as the resin compound (A) for the surface treatment agent composition, and the cationic urethane resin (B) (Table 4), the silane coupling agent (C) (Table 5), A titanium compound (D) (Table 6) and an acid compound (E) (Table 7) were appropriately blended and stirred for a required time using a stirrer to prepare a surface treating agent composition.
[0060]
The plated steel sheet shown in Table 2, which is a surface-treated steel sheet for home appliances, building materials, and automobile parts based on cold-rolled steel sheets, was used as a processing original sheet (see Table 2). In addition, the predetermined plate thickness was employ | adopted for the plate | board thickness of the steel plate according to the objective of evaluation. After the surface of this plated steel sheet was subjected to alkaline degreasing treatment, washed with water and dried, the above-mentioned surface treatment agent composition was applied with a roll coater and dried by heating at various temperatures without being washed with water. The film thickness of the film was adjusted by the solid content (heat residue) of the surface treatment composition or coating conditions (rolling force of roll, rotational speed, etc.). The film composition and quality performance (film appearance, initial thin rust resistance, white complex resistance, blackening resistance, electrokinetic property, fingerprint resistance, paint adhesion) of the obtained surface treated steel sheet were tested. The results are shown in Tables 8-10. The quality performance was evaluated as follows.
[0061]
(1) Coating appearance For each sample, the uniformity of coating appearance (with or without unevenness) was visually evaluated. The evaluation criteria are as follows.
[0062]
○: Uniform appearance without any unevenness Δ: Appearance in which unevenness is slightly conspicuous ×: Appearance in which unevenness is conspicuous
[0063]
(2) Initial thin rust resistance Each sample was subjected to a salt spray test (JIS-Z-2371) and evaluated by the thin rust area ratio after 24 hours. The evaluation criteria are as follows.
[0064]
◎: No occurrence of thin rust ○: Thin rust area ratio of less than 20% ◯: Thin rust area ratio of 20% or more and less than 50% △: Thin rust area ratio of 50% or more and less than 80% ×: Thin rust area ratio of 80% more than.
[0065]
(3) White rust resistance About each sample, the salt spray test (JIS-Z-2371) was given and it evaluated by the white rust area rate after progress for 120 hours. The evaluation criteria are as follows.
[0066]
A: White rust area ratio of less than 5% B: White rust area ratio of 5% or more, less than 10% B: White rust area ratio of 10% or more, less than 25% Δ: White rust area ratio of 25% or more, less than 50% : White rust area ratio of 50% or more and 100% or less.
[0067]
(4) Color difference ΔL ^* (L ^* a ^* b ^* difference in CIE 1976 brightness L ^* of two object colors in the display system) before and after holding for 24 hours at 80 ° C. and 98% RH Measurements were made. The evaluation criteria are as follows.
[0068]
○: ΔL ^* > − 1 and uniform appearance without unevenness ○ −: −2 <ΔL ^* ≦ −1 and uniform appearance without unevenness Δ: ΔL ^* ≦ −2 and uniform appearance without unevenness Appearance ×: ΔL ^* ≦ −2 and appearance with noticeable unevenness.
[0069]
(5) Conductivity JIS C2550 measured the interlayer insulation resistance value. The evaluation criteria are as follows.
[0070]
○: 3Ω · cm less than ² / piece △: 3Ω · cm ² / or more sheets, 5Ω · cm ² / sheet less than ×: 5Ω · cm ² / or more sheets.
[0071]
(6) Fingerprint resistance The color difference ΔE ^* before and after immersion in the artificial fingerprint liquid was calculated using the following formula (A).
[0072]
ΔE ^* = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2 (A)
^{Here, △ L *, △ a *} , △ L * defines the JIS Z8729 ^{L * a} * ^b * difference CIE1976 lightness ^{L *} of the two object colors in the display system and the color coordinates ^a *, ^{b *} difference It is.
[0073]
[Table 1]

The evaluation criteria are as follows.
[0074]
: ΔE ≦ 1
○: 1 <ΔE ≦ 3
×: ΔE> 3
(7) Paint adhesion For each sample, after applying a melamine-based baking paint (film thickness 30 μm), immerse it in boiling water for 2 hours, and immediately cut the grid (10 × 10, 1 mm interval) Then, adhesion and peeling with an adhesive tape were performed, and the peeled area ratio of the coating film was measured. The evaluation criteria are as follows.
[0075]
A: No peeling O: Peeling area ratio of less than 5% Δ: Peeling area ratio of 5% or more, less than 20% x: Peeling area ratio of 20% or more.
[0076]
[Table 2]

[0077]
[Table 3]

[0078]
[Table 4]

[0079]
[Table 5]

[0080]
[Table 6]

[0081]
[Table 7]

[0082]
[Table 8]

[0083]
[Table 9]

[0084]
[Table 10]

[0085]
As is clear from the results shown in Tables 8 to 10, Examples 1 to 14, Examples 16 to 20, Examples 23 to 27, Examples 29 to 41, and Examples 46 to 49 of the present invention are film appearance, resistance It was excellent in all of initial thin rust resistance, white rust resistance, blackening resistance, conductivity, fingerprint resistance, and paint adhesion. On the other hand, in Comparative Examples 42 to 45 that do not satisfy the requirements for the surface treatment agent of the present invention, all of initial thin rust resistance, white rust resistance, blackening resistance, fingerprint resistance, and paint adhesion are satisfied. There was nothing to do and either was inferior. Moreover, the comparative examples 22 and 28 whose baking temperature (heat drying temperature) was outside the range of the present invention were inferior in white rust resistance. Further, Comparative Example 15 having a thin surface treatment film was inferior in white rust resistance, while Comparative Example 21 having a large film thickness was considerably inferior in conductivity.
[0086]
【The invention's effect】
According to the present invention, it is possible to provide an excellent surface-treated steel sheet that is excellent in corrosion resistance, excellent in fingerprint resistance, blackening resistance and paint adhesion without being subjected to chromate treatment.

Claims (8)

At least one cationic property selected from the resin compound (A) represented by the following general formula (I), the first to third amino groups, and the quaternary ammonium base on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet Cationic urethane resin (B) having a functional group and one or more silane cups having at least one reactive functional group selected from an active hydrogen-containing amino group, an epoxy group, a vinyl group, a mercapto group, and a methacryloxy group A cationic urethane resin containing a ring agent (C), a Ti compound (D), and at least one acid compound (E) selected from phosphoric acid, nitric acid, and acetic acid, or a salt thereof; The total content of B) and the silane coupling agent (C) is the total amount of the resin compound (A), the cationic urethane resin (B) and the silane coupling agent (C). It has a surface treatment film having a film thickness of 0.01 μm to 5 μm formed by applying and drying a surface treatment agent of 1 to 20 mass% and 45 to 85 mass%, respectively, with respect to the shape. A surface-treated steel sheet with excellent white rust resistance.

In the formula, Y ₁ and Y ₂ bonded to the benzene ring are each independently hydrogen or a Z group represented by the following general formula (II) or (III), and Z per benzene ring The average number of group substitutions is 0.2 to 1.0. n represents an integer of 2 to 50.

In the formulas (II) and (III), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a hydroxyalkyl having 1 to 10 carbon atoms. Represents a group, and A ⁻ represents a hydroxide ion or an acid ion. A surface treating agent contains 1-20 mass% of Ti compound (D) with respect to the total solid of the total amount of a resin compound (A), a cationic urethane resin (B), and a silane coupling agent (C). The surface-treated steel sheet having excellent white rust resistance according to claim 1. The surface treatment agent is phosphoric acid, nitric acid and acetic acid, or at least one acid compound (E) selected from salts thereof, resin compound (A), cationic urethane resin (B), and silane coupling agent (C The surface-treated steel sheet excellent in white rust resistance according to claim 1, wherein the surface-treated steel sheet is contained in an amount of 1 to 30% by mass with respect to the total solid content of the total amount of The surface-treated steel sheet according to claim 1, 2, or 3, further comprising an organic resin film having a film thickness of 0.01 µm or more and less than 5 µm on the surface treatment film having a film thickness of 0.01 µm or more and less than 5 µm. A surface-treated steel sheet excellent in white rust resistance, wherein the total film thickness of the organic resin film and the surface-treated film is 5 μm or less. At least one cationic property selected from the resin compound (A) represented by the following general formula (I), the first to third amino groups, and the quaternary ammonium base on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet Cationic urethane resin (B) having a functional group and one or more silane couplings having at least one reactive functional group selected from an active hydrogen-containing amino group, an epoxy group, a vinyl group, a mercapto group, and a methacryloxy group Containing cationic agent (C), Ti compound (D), and at least one acid compound (E) selected from phosphoric acid, nitric acid and acetic acid, or salts thereof, and cationic urethane resin (B) And the total amount of the silane coupling agent (C) is the total amount of the resin compound (A), the cationic urethane resin (B), and the silane coupling agent (C). A surface treatment agent of 1 to 20% by mass and 45 to 85% by mass, respectively, is applied to the minute, and heat-dried at an ultimate plate temperature of 30 ° C. to 300 ° C. without washing with water, and the film thickness is 0.01 A method for producing a surface-treated steel sheet excellent in white rust resistance, characterized by forming a surface-treated film of ˜5 μm.

In the formula, Y ₁ and Y ₂ bonded to the benzene ring are each independently hydrogen or a Z group represented by the following general formula (II) or (III), and Z per benzene ring The average number of group substitutions is 0.2 to 1.0. n represents an integer of 2 to 50.

In the formulas (II) and (III), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a hydroxyalkyl having 1 to 10 carbon atoms. Represents a group, and A ⁻ represents a hydroxide ion or an acid ion. A surface treating agent contains 1-20 mass% of Ti compound (D) with respect to the total solid of the total amount of a resin compound (A), a cationic urethane resin (B), and a silane coupling agent (C). The manufacturing method of the surface treatment steel plate excellent in white rust resistance of Claim 5 characterized by the above-mentioned. The surface treatment agent comprises at least one acid compound (E) selected from phosphoric acid, nitric acid, and acetic acid, or a salt thereof, a resin compound (A), a cationic urethane resin (B), and a silane coupling agent ( The method for producing a surface-treated steel sheet having excellent white rust resistance according to claim 5, wherein the content is 1 to 30% by mass based on the total solid content of C). The method for producing a surface-treated steel sheet according to claim 5, 6 or 7, wherein the surface treatment film is formed to have a thickness of 0.01 µm or more and less than 5 µm, and the surface treatment film is formed on the surface treatment film. An organic resin film having a thickness of 0.01 μm or more and less than 5 μm is further formed so that the total film thickness becomes 0.01 μm or more and 5 μm or less of the surface-treated steel sheet having excellent white rust resistance Production method.