JP2004162097A - Highly corrosion resistant surface treated steel sheet, and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface treated steel sheet which exhibits excellent corrosion resistance without incorporating chromium into a surface film. <P>SOLUTION: A film of a surface treatment composition is formed on the surface of a galvanized steel sheet or the like. The film comprises :(a) an aqueous epoxy resin dispersion solution of resins obtained by reacting a polyalkylene glycol-modified epoxy resin obtained by reacting polyalkylene glycol of a specified molecular weight, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, an epoxy group-containing resin, and a active hydrogen-containing hydrazine derivative; (b) a silane coupling agent, and; (c) phosphoric acid and/or a hexafluoro metal acid. Then, an upper layer film wherein the main component consists of a reaction product between a film forming organic resin and an active hydrogen-containing compound in which part or the whole consists of a hydrazine derivative containing active hydrogen is formed on the upper layer thereof. <P>COPYRIGHT: (C)2004,JPO

Description

上記化学構造式中、ｑは０〜５０の整数、好ましくは１〜４０の整数、特に好ましくは２〜２０の整数である。
このようなビスフェノールＡ型エポキシ樹脂は、当業界において広く知られた製造法により得ることができる。
【００４４】
上記エポキシ基含有樹脂（Ｂ）のエポキシ基と反応する活性水素含有化合物としては、下記のものが挙げられる。
・活性水素を有するヒドラジン誘導体
・活性水素を有する第１級または第２級のアミン化合物
・アンモニア、カルボン酸などの有機酸
・塩化水素などのハロゲン化水素類
・アルコール類、チオール類
・活性水素を有しないヒドラジン誘導体または第３級アミンと酸との混合物である４級塩化剤
上記水性エポキシ樹脂分散液を調整する際には、これらの１種または２種以上を使用できるが、優れた耐食性を得るために、活性水素含有化合物の少なくとも一部（好ましくは全部）は、活性水素を有するヒドラジン誘導体であることが必要である。すなわち、これらのうち活性水素を有するヒドラジン誘導体（Ｃ）を必須成分とし、必要に応じてこのヒドラジン誘導体（Ｃ）以外の活性水素含有化合物（Ｄ）を用いる。
【００４５】
上記活性化水素を有するアミン化合物の代表例としては、以下のものを挙げることができる。
（１） ジエチレントリアミン、ヒドロキシエチルアミノエチルアミン、エチルアミノエチルアミン、メチルアミノプロピルアミンなどの１個の２級アミノ基と１個以上の１級アミノ基を含有するアミン化合物の１級アミノ基を、ケトン、アルデヒドまたはカルボン酸と例えば１００〜２３０℃程度の温度で加熱反応させてアルジミン、ケチミン、オキサゾリンまたはイミダゾリンに変性した化合物；
（２） ジエチルアミン、ジエタノールアミン、ジ−ｎ−または−ｉｏｓ−プロパノールアミン、Ｎ−メチルエタノールアミン、Ｎ−エチルエタノールアミンなどの第２級モノアミン；
【００４６】
（３） モノエタノールアミンなどのようなモノアルカノールアミンとジアルキル（メタ）アクリルアミドとをミカエル付加反応により付加させて得られる第２級アミン含有化合物；
（４） モノエタノールアミン、ネオペンタノールアミン、２−アミノプロパノール、３−アミノプロパノール、２−ヒドロキシ−２′（アミノプロポキシ）エチルエーテルなどのアルカノールアミンの１級アミン基をケチミンに変性した化合物；
【００４７】
活性水素含有化合物の一部として使用できる上記４級塩化剤は、活性水素を有しないヒドラジン誘導体または第３級アミンはそれ自体ではエポキシ基と反応性を有しないので、これらをエポキシ基と反応可能とするために酸との混合物としたものである。４級塩化剤は、必要に応じて水の存在下でエポキシ基と反応し、エポキシ基含有樹脂と４級塩を形成する。４級塩化剤を得るために使用される酸は、酢酸、乳酸などの有機酸、塩酸などの無機酸のいずれでもよい。また、４級塩化剤を得るために使用される活性水素を有しないヒドラジン誘導体としては、例えば３，６−ジクロロピリダジンなどを、また、第３級アミンとしては、例えば、ジメチルエタノールアミン、トリエチルアミン、トリメチルアミン、トリイソプロピルアミン、メチルジエタノールアミンなどを挙げることができる。
【００４８】
上記活性水素含有化合物で最も有用で耐食性に優れた性能を発現するのが、活性水素を有するヒドラジン誘導体である。
活性水素を有するヒドラジン誘導体の具体例としては、例えば以下のものを挙げることができる。
▲１▼ カルボヒドラジド、プロピオン酸ヒドラジド、サリチル酸ヒドラジド、アジピン酸ジヒドラジド、セバシン酸ジヒドラジド、ドデカン酸ジヒドラジド、イソフタル酸ジヒドラジド、チオカルボヒドラジド、４，４′−オキシビスベンゼンスルホニルヒドラジド、ベンゾフェノンヒドラゾン、アミノポリアクリルアミドなどのヒドラジド化合物；
▲２▼ ピラゾール、３，５−ジメチルピラゾール、３−メチル−５−ピラゾロン、３−アミノ−５−メチルピラゾールなどのピラゾール化合物；
【００４９】
▲３▼ １，２，４−トリアゾール、３−アミノ−１，２，４−トリアゾール、４−アミノ−１，２，４−トリアゾール、３−メルカプト−１，２，４−トリアゾール、５−アミノ−３−メルカプト−１，２，４−トリアゾール、２，３−ジヒドロ−３−オキソ−１，２，４−トリアゾール、１Ｈ−ベンゾトリアゾール、１−ヒドロキシベンゾトリアゾール（１水和物）、６−メチル−８−ヒドロキシトリアゾロピリダジン、６−フェニル−８−ヒドロキシトリアゾロピリダジン、５−ヒドロキシ−７−メチル−１，３，８−トリアザインドリジンなどのトリアゾール化合物；
【００５０】
▲４▼ ５−フェニル−１，２，３，４−テトラゾール、５−メルカプト−１−フェニル−１，２，３，４−テトラゾールなどのテトラゾール化合物；
▲５▼ ５−アミノ−２−メルカプト−１，３，４−チアジアゾール、２，５−ジメルカプト−１，３，４−チアジアゾールなどのチアジアゾール化合物；
▲６▼ マレイン酸ヒドラジド、６−メチル−３−ピリダゾン、４，５−ジクロロ−３−ピリダゾン、４，５−ジブロモ−３−ピリダゾン、６−メチル−４，５−ジヒドロ−３−ピリダゾンなどのピリダジン化合物；
また、これらのなかでも５員環または６員環の環状構造を有し、環状構造中に窒素原子を有するピラゾール化合物、トリアゾール化合物が特に好適である。
これらのヒドラジン誘導体は１種を単独でまたは２種以上を混合して使用することができる。
【００５１】
以上述べたようなポリアルキレングリコール変性エポキシ樹脂（Ａ）と、このポリアルキレングリコール変性エポキシ樹脂（Ａ）以外のエポキシ基含有樹脂（Ｂ）と、活性水素を有するヒドラジン誘導体（Ｃ）と、さらに必要に応じてこのヒドラジン誘導体（Ｃ）以外の活性水素含有化合物（Ｄ）とを、好ましくは１０〜３００℃、より好ましくは５０〜１５０℃の温度で約１〜８時間反応させ、これにより得られる樹脂を水中に分散させることにより、上述した水性エポキシ樹脂分散液を得ることができる。
【００５２】
上記反応は有機溶剤を加えて行ってもよく、使用する有機溶剤の種類は特に限定されない。例えば、アセトン、メチルエチルケトン、メチルイソブチルケトン、ジブチルケトン、シクロヘキサノンなどのケトン類；エタノール、ブタノール、２−エチルヘキシルアルコール、ベンジルアルコール、エチレングリコール、エチレングリコールモノイソプロピルエーテル、エチレングリコールモノブチルエーテル、エチレングリコールモノヘキシルエーテル、プロピレングリコール、プロピレングリコールモノメチルエーテル、ジエチレングリコール、ジエチレングリコールモノエチルエーテル、ジエチレングリコールモノブチルエーテルなどの水酸基を含有するアルコール類やエーテル類；酢酸エチル、酢酸ブチル、エチレングリコールモノブチルエーテルアセテートなどのエステル類；トルエン、キシレンなどの芳香族炭化水素等を例示でき、これらの１種または２種以上を使用することができる。また、これらのなかでエポキシ樹脂との溶解性、皮膜形成性等の面からは、ケトン系またはエーテル系の溶剤が特に好ましい。
【００５３】
ポリアルキレングリコール変性エポキシ樹脂（Ａ）と、ポリアルキレングリコール変性エポキシ樹脂（Ａ）以外のエポキシ基含有樹脂（Ｂ）と、活性水素を有するヒドラジン誘導体（Ｃ）との配合比率は、ポリアルキレングリコール変性エポキシ樹脂（Ａ）およびエポキシ基含有樹脂（Ｂ）中のエポキシ基に対するヒドラジン誘導体（Ｃ）中の活性水素基の当量比が０．０１〜１０、好ましくは０．１〜８、さらに好ましくは０．２〜４となるようにすることが、耐食性や樹脂の水分散性などの観点から適当である。
また、活性水素を有するヒドラジン誘導体（Ｃ）の一部を活性水素含有化合物（Ｄ）に置き換えることもできるが、置き換える量としては９０モル％以下、好ましくは７０モル％以下、より好ましくは１０〜６０モル％の範囲内とすることが防食性、付着性の観点から適当である。
【００５４】
また、緻密なバリア皮膜を形成するために、樹脂組成物中に硬化剤を配合し、皮膜を加熱硬化させることが望ましい。樹脂組成物による皮膜を形成する場合の硬化方法としては、（１）イソシアネートと基体樹脂中の水酸基とのウレタン化反応を利用する硬化方法、（２）メラミン、尿素およびベンゾグアナミンの中から選ばれた１種以上にホルムアルデヒドを反応させてなるメチロール化合物の一部若しくは全部に炭素数１〜５の１価アルコールを反応させてなるアルキルエーテル化アミノ樹脂と基体樹脂中の水酸基との間のエーテル化反応を利用する硬化方法、が適当であるが、このうちイソシアネートと基体樹脂中の水酸基とのウレタン化反応を主反応とすることが特に好適である。
【００５５】
上記（１）の硬化方法で用いることができる硬化剤としてのポリイソシアネート化合物は、１分子中に少なくとも２個のイソシアネート基を有する脂肪族、脂環族（複素環を含む）または芳香族イソシアネート化合物、若しくはそれらの化合物を多価アルコールで部分反応させた化合物である。このようなポリイソシアネート化合物としては、例えば以下のものが例示できる。
【００５６】
▲１▼ ｍ−またはｐ−フェニレンジイソシアネート、２，４−または２，６−トリレンジイソシアネート、ｏ−またはｐ−キシリレンジイソシアネート、ヘキサメチレンジイソシアネート、ダイマー酸ジイソシアネート、イソホロンジイソシアネート
▲２▼ 上記▲１▼の化合物単独またはそれらの混合物と多価アルコール（エチレングリコール、プロピレングリコールなどの２価アルコール類；グリセリン、トリメチロールプロパンなどの３価アルコール；ペンタエリスリトールなどの４価アルコール；ソルビトール、ジペンタエリスリトールなどの６価アルコールなど）との反応生成物であって、１分子中に少なくとも２個のイソシアネートが残存する化合物
これらのポリイソシアネート化合物は、１種を単独でまたは２種以上を混合して使用できる。
【００５７】
また、ポリイソシアネート化合物の保護剤（ブロック剤）としては、例えば、
▲１▼ メタノール、エタノール、プロパノール、ブタノール、オクチルアルコールなどの脂肪族モノアルコール類；
▲２▼ エチレングリコールおよび／またはジエチレングリコールのモノエーテル類、例えば、メチル、エチル、プロピル（ｎ−，ｉｓｏ）、ブチル（ｎ−，ｉｓｏ，ｓｅｃ）などのモノエーテル；
▲３▼ フェノール、クレゾールなどの芳香族アルコール；
▲４▼ アセトオキシム、メチルエチルケトンオキシムなどのオキシム；
などが使用でき、これらの１種または２種以上と前記ポリイソシアネート化合物とを反応させることにより、少なくとも常温下で安定に保護されたポリイソシアネート化合物を得ることができる。
【００５８】
このようなポリイソシアネート化合物（ａ２）は、水性エポキシ樹脂分散液（ａ）（上記成分（ａ））に対して、硬化剤として（ａ）／（ａ２）＝９５／５〜５５／４５（不揮発分の質量比）、好ましくは（ａ）／（ａ２）＝９０／１０〜６５／３５の割合で配合するのが適当である。ポリイソシアネート化合物には吸水性があり、これを（ａ）／（ａ２）＝５５／４５を超えて配合すると表面処理皮膜の密着性を劣化させてしまう。さらに、未反応のポリイソシアネート化合物が上層皮膜中に移動し、上層皮膜の硬化阻害や密着性不良を起こしてしまう。このような観点から、ポリイソシアネート化合物（ａ２）の配合量は（ａ）／（ａ２）＝５５／４５以下とすることが好ましい。
【００５９】
なお、水分散性樹脂は以上のような架橋剤（硬化剤）の添加により十分に架橋するが、さらに低温架橋性を増大させるため、公知の硬化促進触媒を使用することが望ましい。この硬化促進触媒としては、例えば、Ｎ−エチルモルホリン、ジブチル錫ジラウレート、ナフテン酸コバルト、塩化第１スズ、ナフテン酸亜鉛、硝酸ビスマスなどが使用できる。
また、付着性など若干の物性向上を狙いとして、エポキシ基含有樹脂（Ｂ）とともに公知のアクリル、アルキッド、ポリエステル等の樹脂を混合して用いることもできる。
【００６０】
ポリアルキレングリコール変性エポキシ樹脂（Ａ）、エポキシ基含有樹脂（Ｂ）および活性水素を有するヒドラジン誘導体（Ｃ）（さらに必要に応じて活性水素含有化合物（Ｄ））の反応生成物を水分散化するには、例えば以下のような手法を採ることができる。
▲１▼ エポキシ基含有樹脂（すなわち、樹脂（Ａ），（Ｂ））のエポキシ基と活性水素含有化合物である二塩基酸または第２級アミンなどを反応させ、中和剤である３級アミン、酢酸または燐酸などで中和、水分散化させる手法
▲２▼ エポキシ樹脂とポリエチレングリコール、ポリプロピレングリコールなどの末端水酸基含有ポリアルキレンオキサイドをイソシアネートと反応させてなる変性エポキシ樹脂を分散剤に用いて、水分散化させる手法
▲３▼ 上記▲１▼と▲２▼を併用する手法
【００６１】
表面処理組成物には、上述した特定の水分散性樹脂以外に、その他の水分散性樹脂および／または水溶性樹脂として、例えば、アクリル系樹脂、ウレタン系樹脂、ポリエステル系樹脂、エポキシ系樹脂、エチレン系樹脂、アルキッド系樹脂、フェノール樹脂、オレフィン樹脂などの１種または２種以上を、全樹脂固形分中での割合で１５ｍａｓｓ％程度を上限として配合してもよい。
【００６２】
次に、上記成分（ｂ）であるシランカップリング剤について説明する。
このシランカップリング剤としては、例えば、ビニルメトキシシラン、ビニルエトキシシラン、ビニルトリクロロシラン、ビニルトリメトキシシラン、ビニルトリエトキシシラン、β−（３，４エポキシシクロヘキシル）エチルトリメトキシシラン、γ−グリシドキシプロピルトリメトキシシラン、γ−グリシドキシプロピルメチルジエトキシシラン、γ−グリシドキシプロピルトリエトキシシラン、Ｎ−β（アミノエチル）γ−アミノプロピルメチルジメトキシシラン、Ｎ−β（アミノエチル）γ−アミノプロピルトリメトキシシラン、Ｎ−β（アミノエチル）γ−アミノプロピルトリメエキシシラン、γ−アミノプロピルトリメトキシシラン、γ−アミノプロピルトリエトキシシラン、γ−メタクリロキシプロピルメチルジメトキシシラン、γ−メタクリロキシプロピルトリメトキシシラン、γ−メタクリロキシプロピルメチルジエトキシシラン、γ−メタクリロキシプロピルトリエトキシシラン、γ−メルカプトプロピルメチルジメトキシシラン、γ−メルカプトプロピルトリメトキシシラン、ｐ−スチリルトリメトキシシラン、γ−アクリロキシプロピルトリメトキシシラン、Ｎ−フェニル−γ−アミノプロピルトリメトキシシラン、γ−ウレイドプロピルトリエトキシシラン、γ−クロロプロピルトリメトキシシラン、ビス（トリエトキシシリルプロピル）テトラスルフィド、γ−イソシアネートプロピルトリエトキシシラン、γ−トリエトキシシリル−Ｎ−（１，３−ジメチル−ブチリデン）プロピルアミン、Ｎ−（ビニルベンジルアミン）−β−アミノエチル−γ−アミノプロピルトリメトキシシランなどを挙げることができ、これらの１種を単独でまたは２種以上を混合して使用することができる。
【００６３】
本発明において、表面処理組成物が特定の酸成分とともにシランカップリング剤を含むことにより耐白錆性が向上するには、先に述べたような理由が考えられる。
また、上記シランカップリング剤のなかでも、上記成分（ａ）の水分散性樹脂と反応性が高い官能基を有するという観点から、特に反応性官能基としてアミノ基を有すシランカップリング剤が好ましい。このようなシランカップリング剤としては、例えば、Ｎ−β（アミノエチル）γ−アミノプロピルメチルジメトキシシラン、Ｎ−β（アミノエチル）γ−アミノプロピルトリメトキシシラン、Ｎ−β（アミノエチル）γ−アミノプロピルトリメエキシシラン、γ−アミノプロピルトリメトキシシラン、γ−アミノプロピルトリエトキシシランなどが挙げられ、具体的には、信越化学（株）製の「ＫＢＭ−９０３」、「ＫＢＥ−９０３」、「ＫＢＭ−６０３」、「ＫＢＥ−６０２」、「ＫＢＥ−６０３」（いずれも商品名）などを用いることができる。
【００６４】
シランカップリング剤の配合量は、上記成分（ａ）である水性エポキシ樹脂分散液の固形分１００質量部に対して１〜３００質量部、好ましくは５〜１００質量部、さらに好ましくは１５〜５０質量部とするのが適当である。シランカップリング剤の配合量が１質量部未満では耐食性が劣り、一方、３００質量部を超えると十分な皮膜が形成できないため、水分散性樹脂との密着性とバリア性を高める効果が発揮できず、耐食性が低下する。
【００６５】
次に、上記成分（ｃ）であるリン酸および／またはヘキサフルオロ金属酸は、不活性なめっき金属表面に作用してめっき金属表面を活性化させる作用を有する。このリン酸とヘキサフルオロ金属酸はそれぞれ単独で用いてもよいし、併用してもよい。
ヘキサフルオロ金属酸の種類は特に限定されないが、特にフッ化チタン酸、フッ化ジルコン酸、けいフッ酸などのようなＴｉ、Ｓｉ、Ｚｒの中から選ばれる１種以上の元素を含むヘキサフルオロ金属酸が好ましく、これらの１種または２種以上を用いることができる。
【００６６】
リン酸および／またはヘキサフルオロ金属酸の配合量は、上記成分（ａ）である水性エポキシ樹脂分散液の固形分１００質量部に対して、合計で０．１〜８０質量部、好ましくは１〜６０質量部、さらに好ましくは５〜５０質量部とするのが適当である。リン酸および／またはヘキサフルオロ金属酸の配合量が０．１質量部未満では耐食性が劣り、一方、８０質量部を超えると皮膜の可溶成分が増えることから、耐食性が低下するため好ましくない。
【００６７】
表面処理組成物には、耐食性向上を目的として、必要に応じて水溶性リン酸塩を配合することができる。この水溶性リン酸塩としては、例えば、オルトリン酸、ピロリン酸、ポリリン酸、メタリン酸などの金属塩の１種又は２種以上を用いることができる。また、有機リン酸の塩（例えば、フィチン酸、フィチン酸塩、ホスホン酸、ホスホン酸塩およびこれらの金属塩）の１種以上を添加してもよい。また、それらのなかでも第一リン酸塩が表面処理組成物の安定性などの面から好適である。
皮膜中でのリン酸塩の存在形態も特別な限定はなく、また、結晶若しくは非結晶であるか否かも問わない。また、皮膜中でのリン酸塩のイオン性、溶解度についても特別な制約はない。水溶性リン酸塩を配合することにより耐食性が向上する理由は、水溶性リン酸塩が皮膜形成時に緻密な難溶性化合物を形成するためであると考えられる。
【００６８】
先に述べたようにシランカップリング剤は活性化されためっき金属と皮膜形成樹脂の両方と化学結合することで、めっき金属と皮膜形成樹脂との優れた密着性と耐食性が得られるが、めっき金属表面には不可避的に不活性な部分が存在し、このような不活性なサイトでは上記化学結合が生じにくく防錆効果を十分発揮できない。水溶性リン酸塩はこのようなめっき皮膜の部分に対して、皮膜形成時に緻密な難溶性化合物を形成する。すなわち、水溶性リン酸塩のリン酸イオンによるめっき皮膜の溶解に伴いめっき皮膜／表面処理組成物界面でｐＨが上昇し、その結果、水溶性リン酸塩の沈殿物皮膜が形成され、これが耐食性の向上に寄与する。
【００６９】
また、特に優れた耐食性を得るというの観点からは、水溶性リン酸塩のカチオン種としてはＡｌ、Ｍｎ、Ｎｉ、Ｍｇが特に望ましく、これらの中から選ばれる１種以上の元素を含む水溶性リン酸塩を用いることが好ましい。このような水溶性リン酸塩としては、例えば、第一リン酸アルミニウム、第一リン酸マンガン、第一リン酸ニッケル、第一リン酸マグネシウムが挙げられ、これらのうちでも特に第一リン酸アルミニウムが最も好ましい。また、そのカチオン成分とＰ_２Ｏ_５成分のモル比［カチオン］／［Ｐ_２Ｏ_５］は０．４〜１．０であることが好ましい。モル比［カチオン］／［Ｐ_２Ｏ_５］が０．４未満では可溶性のリン酸によって皮膜の難溶性が損なわれ、耐食性が低下するので好ましくない。一方、１．０を超えると処理液安定性が著しく失われるので好ましくない。
【００７０】
この水溶性リン酸塩の配合量は、上記成分（ａ）である水性エポキシ樹脂分散液の固形分１００質量部に対して、固形分の割合で０．１〜６０質量部、好ましくは０．５〜４０質量部、さらに好ましくは１〜３０質量部とするのが適当である。水溶性リン酸塩の配合量が０．１質量部未満では耐食性の向上効果が十分でなく、一方、６０質量部を超えると皮膜の可溶成分が増えることから、耐食性が低下するため好ましくない。
【００７１】
表面処理組成物には、耐食性向上を目的として、必要に応じて非クロム系防錆添加剤を配合することができる。表面処理組成物中にこのような非クロム系防錆添加剤を配合することにより、特に優れた防食性能（自己補修性）を得ることができる。
この非クロム系防錆添加剤は、特に下記（ｅ１）〜（ｅ５）の中から選ばれる１つ以上を用いることが好ましい。
（ｅ１）酸化ケイ素
（ｅ２）カルシウム又はカルシウム化合物
（ｅ３）難溶性リン酸化合物
（ｅ４）モリブデン酸化合物
（ｅ５）トリアゾール類、チオール類、チアジアゾール類、チアゾール類、チウラム類の中から選ばれる１種以上の、Ｓ原子を含有する有機化合物
これら（ｅ１）〜（ｅ５）の非クロム系防錆添加剤の詳細及び防食機構は以下の通りである。
【００７２】
まず、上記（ｅ１）の成分としては微粒子シリカであるコロイダルシリカや乾式シリカを使用することができるが、耐食性の観点からは特に、カルシウムをその表面に結合させたカルシウムイオン交換シリカを使用するのが望ましい。
コロイダルシリカとしては、例えば、日産化学（株）製のスノーテックスＯ、２０、３０、４０、Ｃ、Ｓ（いずれも商品名）を用いることができ、また、ヒュームドシリカとしては、日本アエロジル（株）製のＡＥＲＯＳＩＬ Ｒ９７１、Ｒ８１２、Ｒ８１１、Ｒ９７４、Ｒ２０２、Ｒ８０５、１３０、２００、３００、３００ＣＦ（いずれも商品名）を用いることができる。また、カルシウムイオン交換シリカとしては、Ｗ．Ｒ．Ｇｒａｃｅ＆Ｃｏ．製のＳＨＩＥＬＤＥＸ Ｃ３０３、ＳＨＩＥＬＤＥＸ ＡＣ３、ＳＨＩＥＬＤＥＸ ＡＣ５（いずれも商品名）、富士シリシア化学（株）製のＳＨＩＥＬＤＥＸ、ＳＨＩＥＬＤＥＸ ＳＹ７１０（いずれも商品名）などを用いることができる。これらシリカは、腐食環境下において緻密で安定な亜鉛の腐食生成物の生成に寄与し、この腐食生成物がめっき表面に緻密に形成されることによって、腐食の促進を抑制する。
【００７３】
また、上記（ｅ２）、（ｅ３）の成分は沈殿作用によって特に優れた防食性能（自己補修性）を発現する。
上記（ｅ２）の成分であるカルシウム化合物は、カルシウム酸化物、カルシウム水酸化物、カルシウム塩のいずれでもよく、これらの１種または２種以上を使用できる。また、カルシウム塩の種類にも特に制限はなく、ケイ酸カルシウム、炭酸カルシウム、リン酸カルシウムなどのようなカチオンとしてカルシウムのみを含む単塩のほか、リン酸カルシウム・亜鉛、リン酸カルシウム・マグネシウムなどのようなカルシウムとカルシウム以外のカチオンを含む複塩を使用してももよい。この（ｅ２）の成分は、腐食環境下においてめっき金属である亜鉛やアルミニウムよりも卑なカルシウムが優先溶解し、これがカソード反応により生成したＯＨ⁻と緻密で難溶性の生成物として欠陥部を封鎖し、腐食反応を抑制する。また、上記のようなシリカとともに配合された場合には、表面にカルシウムイオンが吸着し、表面電荷を電気的に中和して凝集する。その結果、緻密で且つ難溶性の保護皮膜が生成して腐食が封鎖し、腐食反応を抑制する。
【００７４】
また、上記（ｅ３）である難溶性リン酸化合物としては、難溶性リン酸塩を用いることができる。この難溶性リン酸塩は単塩、複塩などの全ての種類の塩を含む。また、それを構成する金属カチオンに限定はなく、難溶性のリン酸亜鉛、リン酸マグネシウム、リン酸カルシウム、リン酸アルミニウムなどのいずれの金属カチオンでもよい。また、リン酸イオンの骨格や縮合度などにも限定はなく、正塩、二水素塩、一水素塩または亜リン酸塩のいずれでもよく、さらに、正塩はオルトリン酸塩の他、ポリリン酸塩などの全ての縮合リン酸塩を含む。この難溶性リン化合物は、腐食によって溶出しためっき金属の亜鉛やアルミニウムが、加水分解により解離したリン酸イオンと錯形成反応により緻密で且つ難溶性の保護皮膜を生成して腐食起点を封鎖し、腐食反応を抑制する。
【００７５】
また、上記（ｅ４）のモリブデン酸化合物としては、例えば、モリブデン酸塩を用いることができる。このモリブデン酸塩は、その骨格、縮合度に限定はなく、例えばオルトモリブデン酸塩、パラモリブデン酸塩、メタモリブデン酸塩などが挙げられる。また、単塩、複塩などの全ての塩を含み、複塩としてはリン酸モリブデン酸塩などが挙げられる。モリブデン酸化合物は不動態化効果によって自己補修性を発現する。すなわち、腐食環境下で溶存酸素と共にめっき皮膜表面に緻密な酸化物を形成することで腐食起点を封鎖し、腐食反応を抑制する。
【００７６】
また、上記（ｅ５）の有機化合物としては、例えば、以下のようなものを挙げることができる。すなわち、トリアゾール類としては、１，２，４−トリアゾール、３−アミノ−１，２，４−トリアゾール、３−メルカプト−１，２，４−トリアゾール、５−アミノ−３−メルカプト−１，２，４−トリアゾール、１Ｈ−ベンゾトリアゾールなどが、またチオール類としては、１，３，５−トリアジン−２，４，６−トリチオール、２−メルカプトベンツイミダゾールなどが、またチアジアゾール類としては、５−アミノ−２−メルカプト−１，３，４−チアジアゾール、２，５−ジメルカプト−１，３，４−チアジアゾールなどが、またチアゾール類としては、２−Ｎ，Ｎ−ジエチルチオベンゾチアゾール、２−メルカプトベンゾチアゾール類などが、またチウラム類としては、テトラエチルチウラムジスルフィドなどが、それぞれ挙げられる。これらの有機化合物は吸着効果によって自己補修性を発現する。すなわち、腐食によって溶出した亜鉛やアルミニウムがこれらの有機化合物が有する硫黄を含む極性基に吸着して不活性皮膜を形成することで腐食起点を封鎖し、腐食反応を抑制する。
【００７７】
非クロム系防錆添加剤の配合量は、上記成分（ａ）である水性エポキシ樹脂分散液の固形分１００質量部に対して、固形分の割合で０．１〜５０質量部、好ましくは０．５〜３０質量部とするのが適当である。この非クロム系防錆添加剤の配合量が０．１質量部未満では、耐アルカリ脱脂後の耐食性向上効果が十分に得られず、一方、５０質量部を超えると塗装性及び加工性が低下するだけでなく、耐食性も低下するので好ましくない。
なお、上記（ｅ１）〜（ｅ５）の防錆添加剤を２種以上複合添加してもよく、この場合にはそれぞれ固有の防食作用が複合化されるため、より高度の耐食性が得られる。特に、上記（ｅ１）の成分としてカルシウムイオン交換シリカを用い、且つこれに（ｅ３）、（ｅ４）、（ｅ５）の成分の１種以上、特に好ましくは（ｅ３）〜（ｅ５）の成分の全部を複合添加した場合に特に優れた耐食性が得られる。
【００７８】
また、表面処理皮膜（および表面処理組成物）中には、腐食抑制剤として、他の酸化物微粒子（例えば、酸化アルミニウム、酸化ジルコニウム、酸化チタン、酸化セリウム、酸化アンチモンなど）、リンモリブデン酸塩（例えば、リンモリブデン酸アルミニウムなど）、有機インヒビター（例えば、ヒドラジンおよびその誘導体、チオール化合物、チオカルバミン酸塩など）などの１種または２種以上を添加できる。
【００７９】
さらに必要に応じて、表面処理皮膜（および表面処理組成物）中には添加剤として、有機着色顔料（例えば、縮合多環系有機顔料、フタロシアニン系有機顔料など）、着色染料（例えば、水溶性アゾ系金属染料など）、無機顔料（例えば、酸化チタンなど）、導電性顔料（例えば、亜鉛、アルミニウム、ニッケルなどの金属粉末、リン化鉄、アンチモンドープ型酸化錫など）、カップリング剤（例えば、チタンカップリング剤など）、メラミン・シアヌル酸付加物などの１種または２種以上を添加することができる。
以上のような成分を含む表面処理組成物により形成される表面処理皮膜は、乾燥膜厚が０．０１〜１．０μｍ、好ましくは０．１〜０．８μｍとする。乾燥膜厚が０．０１μｍ未満では耐食性が不十分であり、一方、１．０μｍを超えると導電性や加工性が低下する。
【００８０】
次に、以上述べた表面処理皮膜の具体的な皮膜構造について説明する。
本発明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の皮膜構造は、Ｐ、Ｚｎまたは／およびＡｌ、およびＯを含有する非晶質化合物層と、その上層のヒドラジン誘導体で変性した特定のエポキシ基含有樹脂、すなわち、数平均分子量４００〜２００００のポリアルキレングリコール、ビスフェノール型エポキシ樹脂、活性水素含有化合物およびポリイソシアネート化合物を反応させて得られたポリアルキレングリコール変性エポキシ樹脂（Ａ）と、このポリアルキレングリコール変性エポキシ樹脂（Ａ）以外のエポキシ基含有樹脂（Ｂ）と、活性水素を有するヒドラジン誘導体（Ｃ）と、さらに必要に応じてこのヒドラジン誘導体（Ｃ）以外の活性水素含有化合物（Ｄ）とを反応させて得られた水分散性樹脂をマトリックスとする有機樹脂マトリックス層とからなるもので、好ましくは皮膜（非晶質化合物層または／および有機樹脂マトリックス層）中に、Ｐ、Ｚｎまたは／およびＡｌ、およびＯを含む析出化合物、さらに好ましくはＰ、Ｚｎまたは／およびＡｌ、ＳｉおよびＯを含む析出化合物を含有したものである。この表面処理皮膜はクロムを全く含まない。
【００８１】
亜鉛系めっき鋼板などの下地めっき鋼板に、クロムフリー皮膜によって優れた耐食性（耐白錆性）を付与するためは、先に述べたように、
▲１▼ 有機樹脂によって腐食因子の拡散障壁となる高度なバリア層を形成し、カソード反応を抑制する。
▲２▼ 表面処理組成物とめっき皮膜表層との反応によってめっき皮膜表層に緻密な不活性層（反応層）を形成し、この不活性層によるめっき皮膜表面の不活性化作用によってアノード反応を抑制する。
ことが効果的であり、さらに好ましくは、
▲３▼ 上記不活性層の欠損部分（若しくは破損部分）と反応してこれを修復し、その部分から溶出しようとする亜鉛イオンなどの金属イオンを捕捉・難溶化する自己補修物質を有する（すなわち、自己補修性を有する）。
ことが効果的である。
【００８２】
本発明の表面処理鋼板が有する上記表面処理皮膜によれば、上層側の有機樹脂マトリックス層によって高度のバリア性（上記▲１▼の作用）が付与されるとともに、下層側の非晶質化合物層によってめっき皮膜表層の不活性化作用（上記▲２▼の作用）が付与され、さらに、好ましくは皮膜中に含有する析出化合物により自己補修性（上記▲３▼の作用）が付与され、これらの複合的な作用により表面処理鋼板に高度な耐食性が付与されることになる。
上記非晶質化合物層は、表面処理組成物とめっき皮膜表層とが反応することにより生成した非晶質化合物の濃化層ないし皮膜であり、めっき皮膜成分であるＺｎ，Ａｌに由来するＺｎまたは／およびＡｌを含む化合物からなるものである。めっき鋼板が亜鉛系めっき鋼板である場合、上記非晶質化合物の組成上の特徴は、ＺｎとＰを等モル含むこと、より具体的には、ＺｎとＰのモル比［Ｚｎ］／［Ｐ］が０．９〜１．４である点にある。この化合物は第二リン酸塩系の化合物（例えば、ＺｎＨＰＯ_４・２Ｈ_２Ｏ）であると推定される。
【００８３】
このような非晶質化合物層が形成されることにより優れた耐白錆性が得られるのは、すでに述べたように、この非晶質化合物層がめっき層表層を不活性化することにより、腐食因子が上層側のバリア層（有機樹脂マトリックス層）を突き抜けてめっき皮膜の表面に至っても、白錆の発生に関わるアノード反応が抑制されるためであると考えられる。
この非晶質化合物層の層厚は、耐食性の点から１０ｎｍ以上であることが好ましい。
非晶質化合物層を積極的に形成させるためには、表面処理組成物を塗布した後の加熱処理を誘導加熱方式（誘導加熱炉）で行うことが好ましい。これは、誘導加熱方式による加熱では、鋼板側から加熱されるためめっき皮膜と表面処理組成物との反応が促進され、非晶質化合物層の生成に有利な条件となるからである。
【００８４】
表面処理皮膜は、通常、表面処理組成物に含まれるシランカップリング剤に由来するシラン化合物を含有している。なお、このシラン化合物は、シランカップリング剤としての組成で含有されている場合も含む。
また、表面処理皮膜により高度な耐白錆性を付与するためには、表面処理皮膜が特定の析出化合物を含有することが好ましい。この析出化合物は、Ｐ、Ｚｎまたは／およびＡｌ、及びＯを含む非晶質の析出化合物であり、さらにこの析出化合物がＳｉを含むことにより、耐白錆性の向上効果がより高められる。この析出化合物中に含まれるＺｎ，Ａｌはめっき皮膜成分であるＺｎ，Ａｌに由来するものであり、また、Ｓｉは表面処理組成物に含まれるシランカップリング剤に由来するものである。
【００８５】
上記析出化合物は、めっき皮膜から溶解しためっき金属と表面処理組成物中の主として酸成分との反応生成物（化合物）であると考えられ、表面処理組成物中に適量の酸成分（リン酸など）を含ませることにより皮膜中に生成（析出）させることができる。また、上記析出物のうち、Ｓｉを含有する析出化合物は、表面処理組成物中のシランカップリング剤成分が化合物中に取り込まれたものであり、このような析出化合物も表面処理組成物中のシランカップリング剤の添加量を適正化（添加量を比較的多目にする）することにより皮膜中に生成（析出）させることができる。
【００８６】
表面処理皮膜中に上記析出化合物が含有されることにより耐白錆性が向上する理由は必ずしも明らかではないが、析出化合物から溶出したリン酸イオンなどの酸成分が、腐食過程でめっき皮膜から溶出した亜鉛イオンなどの金属イオンと結合して不溶性化合物が生成され、安定な沈殿保護皮膜を形成して腐食を抑制する（自己補修性を発揮する）ためであると推定される。
また、析出化合物にＳｉが含まれることによって、より優れた耐白錆性が得られる理由も必ずしも明らかではないが、Ｓｉの含有によって腐食環境下での析出化合物の溶解性が高まること、析出化合物中のＳｉが非晶質化合物層に取り込まれることにより、腐食過程でめっき皮膜から溶出する亜鉛イオンなどの金属イオンとの反応生成物がより安定になること、などの要因が考えられる。
めっき鋼板が亜鉛系めっき鋼板である場合、通常、表面処理皮膜が含有する析出化合物はＺｎとＰを等モル含むものである。より具体的には、ＺｎとＰのモル比［Ｚｎ］／［Ｐ］が０．９〜１．４であり、この化合物は第二リン酸塩系の化合物（例えば、ＺｎＨＰＯ_４・２Ｈ_２Ｏ）であると推定される。
【００８７】
一方、表面処理皮膜中にＺｎとＰのモル比［Ｚｎ］／［Ｐ］が１．０未満である析出化合物を析出させた場合には、ＺｎとＰを等モル含む析出化合物を析出させた場合に較べて耐白錆性がより向上する。このモル比［Ｚｎ］／［Ｐ］が１．０未満の析出化合物は、水に可溶な第一リン酸塩（例えば、Ｚｎ（Ｈ_２ＰＯ_４）_２・Ｈ_２Ｏ）主体の化合物であると推定される。このような化合物を析出させることによって特に優れた耐白錆性が得られる理由は必ずしも明らかではないが、この析出化合物が、非晶質化合物層の欠損部分から溶出しようとする亜鉛イオンなどの金属イオンと反応して、難溶性の第二リン酸塩（例えば、第二リン酸亜鉛）を形成することで、自己補修物質としての高度の機能を果たすためであると推定される。
【００８８】
以上述べた表面処理皮膜の膜厚は、先に述べたように、０．０１〜２．０μｍ、好ましくは０．１〜１．５μｍである。また、表面処理皮膜中には、先に述べたように非クロム系防錆添加剤、固形潤滑剤などを含有させることができる。
また、表面処理皮膜を形成するための表面処理組成物は、上述したような化合物層（非晶質化合物層）や析出化合物を生成させるため水溶媒系のものである必要があり、したがって、有機樹脂としては水分散性樹脂が用いられる。
【００８９】
次に、上述した表面処理皮膜の皮膜組成の測定方法の詳細について説明する。現在広く用いられている透過電子顕微鏡、エネルギー分散型Ｘ線分析装置により求めた皮膜断面の局所的な組成の定量値は、断面試料の作成方法、データの測定条件、データ処理法、定量補正計算法などによって変わってしまうのが実態である。これは、▲１▼透過電子顕微鏡で観察可能な未知試料に適した元素分析用標準試料を逐次準備することが実質的に不可能であるため、標準試料を用いない理論計算に基づく定量計算を採用せざるを得ず、そのための計算モデルが多様である、▲２▼Ｎａ以下の軽元素に対するＮａ以上の重元素の相対濃度の定量計算方法が世界的にも確立されていない、などの理由によるものである。こうした状況に加えて、断面試料の形状や断面試料の支持台などに起因する、測定対象部分以外からの特性Ｘ線の取り扱い方も定量結果を大きく左右する。
【００９０】
そこで、本発明では、上記皮膜組成の測定に以下のような方法を用いた。まず、透過電子顕微鏡用の断面試料の作成には、日立製作所社製の収束イオンビーム加工装置（Ｆｏｃｕｓｅｄ Ｉｏｎ Ｂｅａｍ： ＦＩＢ）ＦＢ２０００Ａに付設したマイクロサンプリング機構を用いた。なお、ＦＩＢ加工に先立って、断面試料を作成する表面処理鋼板の試料片の表面には、イオンビーム照射によるダメージからこれを保護するため、Ｃの保護膜を２００ｎｍ前後フラッシュ蒸着し、その上にさらにＡｕの保護膜を約１００ｎｍスパッタコーティングした。ＦＩＢ加工装置に導入した供試材の断面試料切り出し部分の表面には、ＦＩＢ加工装置の化学気相蒸着（ＣＶＤ）機構を用いてさらにＣ保護膜を５００ｎｍ前後被覆した上で、断面試料の切り出し加工を行った。マイクロサンプリング機構を用いて取り出した断面試料は、Ｍｏ製の半月板状特殊メッシュの直線部分にＣＶＤ機構を利用して固定した上で、透過電子顕微鏡観察に適する膜厚まで仕上げた。
このようにして作成した断面試料の組成分析には、電界放出型電子銃を搭載したＰｈｉｌｉｐｓ社製の透過電子顕微鏡ＣＭ２０ＦＥＧと、これに付設したＳｕｐｅｒ−ＵＴＷ型検出器を備えたＥＤＡＸ社製のエネルギー分散型Ｘ線分析装置Ｐｈｏｅｎｉｘを用いた。なお、顕微鏡像観察ならびに元素分析時の加速電圧はいずれも２００ｋＶとした。
【００９１】
非晶質化合物層および析出化合物の組成は、これらの位置から収集したスペクトルデータからバックグラウンド除去・ピーク分離・定量補正計算を行って求めた。その際、バックグラウンド処理を自動で行うと軽元素域での正味の強度（ネット強度）が適切に計算されない場合があるため、ピークが出現しないエネルギー位置をマニュアルで指定し、これを結ぶマニュアルバックグラウンド方式で処理（除去）した。ピーク分離では、断面試料の支持台として使用するＭｏメッシュやＡｕの保護層に起因するＭｏとＡｕ、ＦＩＢ加工に起因するＧａなどの特性Ｘ線も考慮した。定量計算はいずれも化成処理皮膜に含まれる各元素のＫ系列の特性Ｘ線を用いて行った。なお、補正計算は薄膜近似で行い、補正因子（いわゆるＫ_ＡＢ因子）にはＺａｌｕｚｅｃのモデルを使用した。
表面処理皮膜の非晶質化合物層および析出化合物のＺｎとＰのモル比は、このようにして求めたＺｎとＰの原子濃度の比として求めることができる。
【００９２】
次に、上記表面処理皮膜の上部に第二層皮膜として形成される上層皮膜（有機皮膜）について説明する。
この上層皮膜は、樹脂組成物の主成分が、皮膜形成有機樹脂（Ｅ）と一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）との反応生成物からなり、皮膜厚が０．５〜２．０μｍの皮膜である。この上層皮膜もクロムを全く含まない。
【００９３】
皮膜形成有機樹脂（Ｅ）の種類としては、一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）と反応して、皮膜形成有機樹脂に活性水素含有化合物（Ｆ）が付加、縮合などの反応により結合でき、且つ皮膜を適切に形成できる樹脂であれば特別な制約はない。この皮膜形成有機樹脂（Ｅ）としては、例えば、エポキシ樹脂、変性エポキシ樹脂、ポリウレタン樹脂、ポリエステル樹脂、アルキド樹脂、アクリル系共重合体樹脂、ポリブタジエン樹脂、フェノール樹脂、およびこれらの樹脂の付加物または縮合物などを挙げることができ、これらのうちの１種を単独でまたは２種以上を混合して使用することができる。
【００９４】
また、皮膜形成有機樹脂（Ｅ）としては、反応性、反応の容易さ、防食性などの点から、樹脂中にエポキシ基を含有するエポキシ基含有樹脂（Ｈ）が特に好ましい。このエポキシ基含有樹脂（Ｈ）としては、一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）と反応して、皮膜形成有機樹脂に活性水素含有化合物（Ｆ）が付加、縮合などの反応により結合でき、且つ皮膜を適切に形成できる樹脂であれば特別な制約はなく、例えば、エポキシ樹脂、変性エポキシ樹脂、エポキシ基含有モノマーと共重合したアクリル系共重合体樹脂、エポキシ基を有するポリブタジエン樹脂、エポキシ基を有するポリウレタン樹脂、およびこれらの樹脂の付加物若しくは縮合物などが挙げられ、これらのエポキシ基含有樹脂の１種を単独でまたは２種以上混合して用いることができる。
また、これらのエポキシ基含有樹脂（Ｈ）の中でも、めっき表面との密着性、耐食性の点からエポキシ樹脂、変性エポキシ樹脂が特に好適である。またその中でも、酸素などの腐食因子に対して優れた遮断性を有する熱硬化性のエポキシ樹脂や変性エポキシ樹脂が最適であり、とりわけ高度な導電性及びスポット溶接性を得るために皮膜の付着量を低レベルにする場合には特に有利である。
【００９５】
上記エポキシ樹脂としては、ビスフェノールＡ、ビスフェノールＦ、ノボラック型フェノールなどのポリフェノール類とエピクロルヒドリンなどのエピハロヒドリンとを反応させてグリシジル基を導入してなるか、若しくはこのグリシジル基導入反応生成物にさらにポリフェノール類を反応させて分子量を増大させてなる芳香族エポキシ樹脂、さらには脂肪族エポキシ樹脂、脂環族エポキシ樹脂などが挙げられ、これらの１種を単独でまたは２種以上を混合して使用することができる。これらのエポキシ樹脂は、特に低温での皮膜形成性を必要とする場合には数平均分子量が１５００以上であることが好適である。
【００９６】
上記変性エポキシ樹脂としては、上記エポキシ樹脂中のエポキシ基または水酸基に各種変性剤を反応させた樹脂を挙げることができ、例えば、乾性油脂肪酸を反応させたエポキシエステル樹脂、アクリル酸またはメタクリル酸などを含有する重合性不飽和モノマー成分で変性したエポキシアクリレート樹脂、イソシアネート化合物を反応させたウレタン変性エポキシ樹脂などを例示できる。
【００９７】
上記エポキシ基含有モノマーと共重合したアクリル系共重合体樹脂としては、エポキシ基を有する不飽和モノマーとアクリル酸エステルまたはメタクリル酸エステルを必須とする重合性不飽和モノマー成分とを、溶液重合法、エマルション重合法または懸濁重合法などによって合成した樹脂を挙げることができる。
上記重合性不飽和モノマー成分としては、例えば、メチル（メタ）アクリレート、エチル（メタ）アクリレート、プロピル（メタ）アクリレート、ｎ−，ｉｓｏ−若しくはｔｅｒｔ−ブチル（メタ）アクリレート、ヘキシル（メタ）アクリレート、２−エチルヘキシル（メタ）アクリレート、デシル（メタ）アクリレート、ラウリル（メタ）アクリレートなどのアクリル酸又はメタクリル酸のＣ１〜２４アルキルエステル；アクリル酸、メタクリル酸、スチレン、ビニルトルエン、アクリルアミド、アクリロニトリル、Ｎ−メチロール（メタ）アクリルアミド、Ｎ−メチロール（メタ）アクリルアミドのＣ１〜４アルキルエーテル化物；Ｎ，Ｎ−ジエチルアミノエチルメタクリレートなどを挙げることができる。
【００９８】
また、エポキシ基を有する不飽和モノマーとしては、グリシジルメタクリレート、グリシジルアクリレート、３，４−エポキシシクロヘキシルメチル（メタ）アクリレートなど、エポキシ基と重合性不飽和基を持つものであれば特別な制約はない。
また、このエポキシ基含有モノマーと共重合したアクリル系共重合体樹脂は、ポリエステル樹脂、エポキシ樹脂、フェノール樹脂などによって変性させた樹脂とすることもできる。
【００９９】
前記エポキシ樹脂として特に好ましいのは、ビスフェノールＡとエピハロヒドリンとの反応生成物である下式に示される化学構造を有する樹脂であり、このエポキシ樹脂は特に耐食性に優れているため好ましい。
【化２】

このようなビスフェノールＡ型エポキシ樹脂の製造法は当業界において広く知られている。また、上記化学構造式において、ｑは０〜５０、好ましくは１〜４０、特に好ましくは２〜２０である。
なお、皮膜形成有機樹脂（Ｅ）は、有機溶剤溶解型、有機溶剤分散型、水溶解型、水分散型のいずれであってもよい。
【０１００】
本発明では皮膜形成有機樹脂（Ｅ）の分子中にヒドラジン誘導体を付与することを狙いとしており、このため活性水素含有化合物（Ｆ）の少なくとも一部（好ましくは全部）は、活性水素を有するヒドラジン誘導体（Ｇ）であることが必要である。
皮膜形成有機樹脂（Ｅ）がエポキシ基含有樹脂である場合、そのエポキシ基と反応する活性水素含有化合物（Ｆ）として例えば以下に示すようなものを例示でき、これらの１種または２種以上を使用できるが、この場合も活性水素含有化合物（Ｆ）の少なくとも一部（好ましくは全部）は、活性水素を有するヒドラジン誘導体であることが必要である。
・活性水素を有するヒドラジン誘導体
・活性水素を有する第１級または第２級のアミン化合物
・アンモニア、カルボン酸などの有機酸
・塩化水素などのハロゲン化水素
・アルコール類、チオール類
・活性水素を有しないヒドラジン誘導体または第３級アミンと酸との混合物である４級塩化剤
【０１０１】
前記活性水素を有するヒドラジン誘導体（Ｇ）としては、例えば、以下のものを挙げることができる。
▲１▼ カルボヒドラジド、プロピオン酸ヒドラジド、サリチル酸ヒドラジド、アジピン酸ジヒドラジド、セバシン酸ジヒドラジド、ドデカン酸ジヒドラジド、イソフタル酸ジヒドラジド、チオカルボヒドラジド、４，４′−オキシビスベンゼンスルホニルヒドラジド、ベンゾフェノンヒドラゾン、アミノポリアクリルアミドなどのヒドラジド化合物；
▲２▼ ピラゾール、３，５−ジメチルピラゾール、３−メチル−５−ピラゾロン、３−アミノ−５−メチルピラゾールなどのピラゾール化合物；
【０１０２】
▲３▼ １，２，４−トリアゾール、３−アミノ−１，２，４−トリアゾール、４−アミノ−１，２，４−トリアゾール、３−メルカプト−１，２，４−トリアゾール、５−アミノ−３−メルカプト−１，２，４−トリアゾール、２，３−ジヒドロ−３−オキソ−１，２，４−トリアゾール、１Ｈ−ベンゾトリアゾール、１−ヒドロキシベンゾトリアゾール（１水和物）、６−メチル−８−ヒドロキシトリアゾロピリダジン、６−フェニル−８−ヒドロキシトリアゾロピリダジン、５−ヒドロキシ−７−メチル−１，３，８−トリアザインドリジンなどのトリアゾール化合物；
【０１０３】
▲４▼ ５−フェニル−１，２，３，４−テトラゾール、５−メルカプト−１−フェニル−１，２，３，４−テトラゾールなどのテトラゾール化合物；
▲５▼ ５−アミノ−２−メルカプト−１，３，４−チアジアゾール、２，５−ジメルカプト−１，３，４−チアジアゾールなどのチアジアゾール化合物；
▲６▼ マレイン酸ヒドラジド、６−メチル−３−ピリダゾン、４，５−ジクロロ−３−ピリダゾン、４，５−ジブロモ−３−ピリダゾン、６−メチル−４，５−ジヒドロ−３−ピリダゾンなどのピリダジン化合物
【０１０４】
また、これらのなかでも、５員環または６員環の環状構造を有し、環状構造中に窒素原子を有するピラゾール化合物、トリアゾール化合物が特に好適である。これらのヒドラジン誘導体は１種を単独でまたは２種以上を混合して使用することができる。
【０１０５】
活性水素含有化合物（Ｆ）の一部として使用できる上記活性水素を有するアミン化合物の代表例としては、例えば、以下のものを挙げることができる。
▲１▼ ジエチレントリアミン、ヒドロキシエチルアミノエチルアミン、エチルアミノエチルアミン、メチルアミノプロピルアミンなどの１個の２級アミノ基と１個以上の１級アミノ基を含有するアミン化合物の１級アミノ基を、ケトン、アルデヒド若しくはカルボン酸と例えば１００〜２３０℃程度の温度で加熱反応させてアルジミン、ケチミン、オキサゾリン若しくはイミダゾリンに変性した化合物；
【０１０６】
▲２▼ ジエチルアミン、ジエタノールアミン、ジ−ｎ−または−ｉｓｏ−プロパノールアミン、Ｎ−メチルエタノールアミン、Ｎ−エチルエタノールアミンなどの第２級モノアミン；
▲３▼ モノエタノールアミンのようなモノアルカノールアミンとジアルキル（メタ）アクリルアミドとをミカエル付加反応により付加させて得られた第２級アミン含有化合物；
▲４▼ モノエタノールアミン、ネオペンタノールアミン、２−アミノプロパノール、３−アミノプロパノール、２−ヒドロキシ−２′（アミノプロポキシ）エチルエーテルなどのアルカノールアミンの１級アミノ基をケチミンに変性した化合物；
【０１０７】
活性水素含有化合物（Ｆ）の一部として使用できる上記４級塩化剤は、活性水素を有しないヒドラジン誘導体または第３級アミンはそれ自体ではエポキシ基と反応性を有しないので、これらをエポキシ基と反応可能とするために酸との混合物としたものである。４級塩化剤は、必要に応じて水の存在下でエポキシ基と反応し、エポキシ基含有樹脂と４級塩を形成する。
４級塩化剤を得るために使用される酸は、酢酸、乳酸などの有機酸、塩酸などの無機酸のいずれでもよい。また、４級塩化剤を得るために使用される活性水素を有しないヒドラジン誘導体としては、例えば３，６−ジクロロピリダジンなどを、また、第３級アミンとしては、例えば、ジメチルエタノールアミン、トリエチルアミン、トリメチルアミン、トリイソプロピルアミン、メチルジエタノールアミンなどを挙げることができる。
【０１０８】
皮膜形成有機樹脂（Ｅ）と一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）との反応生成物は、皮膜形成有機樹脂（Ｅ）と活性水素含有化合物（Ｆ）とを１０〜３００℃、好ましくは５０〜１５０℃で約１〜８時間程度反応させて得られる。
この反応は有機溶剤を加えて行ってもよく、使用する有機溶剤の種類は特に限定されない。例えば、アセトン、メチルエチルケトン、メチルイソブチルケトン、ジブチルケトン、シクロヘキサノンなどのケトン類；エタノール、ブタノール、２−エチルヘキシルアルコール、ベンジルアルコール、エチレングリコール、エチレングリコールモノイソプロピルエーテル、エチレングリコールモノブチルエーテル、エチレングリコールモノヘキシルエーテル、プロピレングリコール、プロピレングリコールモノメチルエーテル、ジエチレングリコール、ジエチレングリコールモノエチルエーテル、ジエチレングリコールモノブチルエーテルなどの水酸基を含有するアルコール類やエーテル類；酢酸エチル、酢酸ブチル、エチレングリコールモノブチルエーテルアセテートなどのエステル類；トルエン、キシレンなどの芳香族炭化水素などを例示でき、これらの１種又は２種以上を使用することができる。また、これらのなかでエポキシ樹脂との溶解性、塗膜形成性などの面からは、ケトン系またはエーテル系の溶剤が特に好ましい。
【０１０９】
皮膜形成有機樹脂（Ｅ）と一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）との配合比率は、固形分の割合で皮膜形成有機樹脂（Ｅ）１００質量部に対して、活性水素含有化合物（Ｆ）を０．５〜２０質量部、特に好ましくは１．０〜１０質量部とするのが望ましい。
また、皮膜形成有機樹脂（Ｅ）がエポキシ基含有樹脂（Ｈ）である場合には、エポキシ基含有樹脂（Ｈ）と活性水素含有化合物（Ｆ）との配合比率は、活性水素含有化合物（Ｆ）の活性水素基の数とエポキシ基含有樹脂（Ｈ）のエポキシ基の数との比率［活性水素基数／エポキシ基数］が０．０１〜１０、より好ましくは０．１〜８、さらに好ましくは０．２〜４とすることが耐食性などの点から適当である。
【０１１０】
また、活性水素含有化合物（Ｆ）中における活性水素を有するヒドラジン誘導体（Ｇ）の割合は１０〜１００モル％、より好ましくは３０〜１００モル％、さら好ましくは４０〜１００モル％とすることが適当である。活性水素を有するヒドラジン誘導体（Ｇ）の割合が１０モル％未満では有機皮膜に十分な防錆機能を付与することができず、得られる防錆効果は皮膜形成有機樹脂とヒドラジン誘導体を単に混合して使用した場合と大差なくなる。
【０１１１】
本発明では緻密なバリヤー皮膜を形成するために、樹脂組成物中に硬化剤を配合し、有機皮膜（上層皮膜）を加熱硬化させることが望ましい。
樹脂組成物皮膜を形成する場合の硬化方法としては、（１）イソシアネートと基体樹脂中の水酸基とのウレタン化反応を利用する硬化方法、（２）メラミン、尿素およびベンゾグアナミンの中から選ばれた１種以上にホルムアルデヒドを反応させてなるメチロール化合物の一部若しくは全部に炭素数１〜５の１価アルコールを反応させてなるアルキルエーテル化アミノ樹脂と基体樹脂中の水酸基との間のエーテル化反応を利用する硬化方法、が適当であるが、このうちイソシアネートと基体樹脂中の水酸基とのウレタン化反応を主反応とすることが特に好適である。
【０１１２】
上記（１）の硬化方法で用いるポリイソシアネート化合物は、１分子中に少なくとも２個のイソシアネート基を有する脂肪族、脂環族（複素環を含む）または芳香族イソシアネート化合物、若しくはそれらの化合物を多価アルコールで部分反応させた化合物である。このようなポリイソシアネート化合物としては、例えば以下のものが例示できる。
▲１▼ ｍ−またはｐ−フェニレンジイソシアネート、２，４−または２，６−トリレンジイソシアネート、ｏ−またはｐ−キシリレンジイソシアネート、ヘキサメチレンジイソシアネート、ダイマー酸ジイソシアネート、イソホロンジイソシアネート
【０１１３】
▲２▼ 上記▲１▼の化合物単独またはそれらの混合物と多価アルコール（エチレングリコール、プロピレングリコールなどの２価アルコール類；グリセリン、トリメチロールプロパンなどの３価アルコール；ペンタエリスリトールなどの４価アルコール；ソルビトール、ジペンタエリスリトールなどの６価アルコールなど）との反応生成物であって、１分子中に少なくとも２個のイソシアネートが残存する化合物
これらのポリイソシアネート化合物は、１種を単独で、または２種以上を混合して使用できる。
【０１１４】
また、ポリイソシアネート化合物の保護剤（ブロック剤）としては、例えば、
▲１▼ メタノール、エタノール、プロパノール、ブタノール、オクチルアルコールなどの脂肪族モノアルコール類
▲２▼ エチレングリコールおよび／またはジエチレングリコールのモノエーテル類、例えば、メチル、エチル、プロピル（ｎ−，ｉｓｏ）、ブチル（ｎ−，ｉｓｏ，ｓｅｃ）などのモノエーテル
▲３▼ フェノール、クレゾールなどの芳香族アルコール
▲４▼ アセトオキシム、メチルエチルケトンオキシムなどのオキシム
などが使用でき、これらの１種または２種以上と前記ポリイソシアネート化合物とを反応させることにより、少なくとも常温下で安定に保護されたポリイソシアネート化合物を得ることができる。
【０１１５】
このようなポリイソシアネート化合物（Ｉ）は、硬化剤として皮膜形成有機樹脂（Ｅ）に対し、（Ｅ）／（Ｉ）＝９５／５〜５５／４５（不揮発分の重量比）、好ましくは（Ｅ）／（Ｉ）＝９０／１０〜６５／３５の割合で配合するのが適当である。ポリイソシアネート化合物には吸水性があり、これを（Ｅ）／（Ｉ）＝５５／４５を超えて配合すると上層皮膜の密着性を劣化させてしまう。さらに、上層皮膜上に上塗り塗装を行った場合、未反応のポリイソシアネート化合物が塗膜中に移動し、塗膜の硬化阻害や密着性不良を起こしてしまう。このような観点から、ポリイソシアネート化合物（Ｉ）の配合量は（Ｅ）／（Ｉ）＝５５／４５以下とすることが好ましい。
【０１１６】
なお、皮膜形成有機樹脂（Ｅ）は以上のような架橋剤（硬化剤）の添加により十分に架橋するが、さらに低温架橋性を増大させるため、公知の硬化促進触媒を使用することが望ましい。この硬化促進触媒としては、例えば、Ｎ−エチルモルホリン、ジブチル錫ジラウレート、ナフテン酸コバルト、塩化第１スズ、ナフテン酸亜鉛、硝酸ビスマスなどが使用できる。
また、例えば皮膜形成有機樹脂（Ｅ）にエポキシ基含有樹脂を使用する場合、付着性など若干の物性向上を狙いとして、エポキシ基含有樹脂とともに公知のアクリル、アルキッド、ポリエステルなどの樹脂を混合して用いることもできる。
【０１１７】
上層皮膜には、耐食性向上を目的として、必要に応じて非クロム系防錆添加剤を含有させることができる。上層皮膜中にこのような非クロム系防錆添加剤を含有させることにより、より優れた防食性能を得ることができる。
この非クロム系防錆添加剤は特に下記（ｅ１）〜（ｅ５）の中から選ばれる１つ以上を用いることが好ましい。
（ｅ１）酸化ケイ素
（ｅ２）カルシウム又はカルシウム化合物
（ｅ３）難溶性リン酸化合物
（ｅ４）モリブデン酸化合物
（ｅ５）トリアゾール類、チオール類、チアジアゾール類、チアゾール類、チウラム類の中から選ばれる１種以上の、Ｓ原子を含有する有機化合物
これら（ｅ１）〜（ｅ５）の非クロム系防錆添加剤の詳細および防食機構は、先に表面処理皮膜に関して述べた通りである。
【０１１８】
非クロム系防錆添加剤の配合量は、皮膜形成用の樹脂組成物の固形分１００質量部に対して、固形分の割合で０．１〜５０質量部、好ましくは０．５〜３０質量部とするのが適当である。この非クロム系防錆添加剤の配合量が０．１質量部未満では、耐アルカリ脱脂後の耐食性向上効果が十分に得られず、一方、５０質量部を超えると塗装性、加工性および溶接性が低下するだけでなく、耐食性も低下するので好ましくない。
なお、上記（ｅ１）〜（ｅ５）の防錆添加剤を２種以上複合添加してもよく、この場合にはそれぞれ固有の防食作用が複合化されるため、より高度の耐食性が得られる。特に、上記（ｅ１）の成分としてカルシウムイオン交換シリカを用い、且つこれに（ｅ３）、（ｅ４）、（ｅ５）の成分の１種以上、特に好ましくは（ｅ３）〜（ｅ５）の成分の全部を複合添加した場合に特に優れた耐食性が得られる。
【０１１９】
また、上層皮膜中には上記の防錆添加成分に加えて、腐食抑制剤として、他の酸化物微粒子（例えば、酸化アルミニウム、酸化ジルコニウム、酸化チタン、酸化セリウム、酸化アンチモンなど）、リンモリブデン酸塩（例えば、リンモリブデン酸アルミニウムなど）、有機リン酸及びその塩（例えば、フィチン酸、フィチン酸塩、ホスホン酸、ホスホン酸塩、及びこれらの金属塩、アルカリ金属塩、アルカリ土類金属塩など）、有機インヒビター（例えば、ヒドラジン誘導体、チオール化合物、ジチオカルバミン酸塩など）などの１種又は２種以上を添加できる。
【０１２０】
上層皮膜中には、さらに必要に応じて、皮膜の加工性を向上させる目的で固形潤滑剤を配合することができる。
本発明に適用できる固形潤滑剤としては、例えば、以下のようなものが挙げられ、これらの１種または２種以上を用いることができる。。
（１）ポリオレフィンワックス、パラフィンワックス：例えば、ポリエチレンワックス、合成パラフィン、天然パラフィン、マイクロワックス、塩素化炭化水素など
（２）フッ素樹脂微粒子：例えば、ポリフルオロエチレン樹脂（ポリ４フッ化エチレン樹脂など）、ポリフッ化ビニル樹脂、ポリフッ化ビニリデン樹脂など
【０１２１】
また、この他にも、脂肪酸アミド系化合物（例えば、ステアリン酸アミド、パルミチン酸アミド、メチレンビスステアロアミド、エチレンビスステアロアミド、オレイン酸アミド、エシル酸アミド、アルキレンビス脂肪酸アミドなど）、金属石けん類（例えば、ステアリン酸カルシウム、ステアリン酸鉛、ラウリン酸カルシウム、パルミチン酸カルシウムなど）、金属硫化物（例えば、二硫化モリブデン、二硫化タングステンなど）、グラファイト、フッ化黒鉛、窒化ホウ素、ポリアルキレングリコール、アルカリ金属硫酸塩などの１種または２種以上を用いてもよい。
【０１２２】
以上の固形潤滑剤の中でも、特に、ポリエチレンワックス、フッ素樹脂微粒子（なかでも、ポリ４フッ化エチレン樹脂微粒子）が好適である。
ポリエチレンワックスとしては、例えば、ヘキスト社製のセリダスト ９６１５Ａ、セリダスト ３７１５、セリダスト ３６２０、セリダスト ３９１０（いずれも商品名）、三洋化成（株）製のサンワックス １３１−Ｐ、サンワックス １６１−Ｐ（いずれも商品名）、三井石油化学（株）製のケミパール Ｗ−１００、ケミパール Ｗ−２００、ケミパール Ｗ−５００、ケミパール Ｗ−８００、ケミパール Ｗ−９５０（いずれも商品名）などを用いることができる。
【０１２３】
また、フッ素樹脂微粒子としては、テトラフルオロエチレン微粒子が最も好ましく、例えば、ダイキン工業（株）製のルブロン Ｌ−２、ルブロン Ｌ−５（いずれも商品名）、三井・デュポン（株）製のＭＰ１１００、ＭＰ１２００（いずれも商品名）、旭アイシーアイフロロポリマーズ（株）製のフルオンディスパージョン ＡＤ１、フルオンディスパージョン ＡＤ２、フルオン Ｌ１４１Ｊ、フルオン Ｌ１５０Ｊ、フルオン Ｌ１５５Ｊ（いずれも商品名）などが好適である。
また、これらのなかで、ポリオレフィンワックスとテトラフルオロエチレン微粒子の併用により特に優れた潤滑効果が期待できる。
【０１２４】
上層皮膜中での固形潤滑剤の配合量は、皮膜形成用の樹脂組成物１００質量部（固形分）に対して、１〜３０質量部（固形分）、好ましくは１〜１０質量部（固形分）とする。固形潤滑剤の配合量が１質量部未満では潤滑効果が乏しく、一方、配合量が３０質量部を超えると塗装性が低下するので好ましくない。
【０１２５】
本発明の表面処理鋼板が有する上層皮膜は、皮膜形成有機樹脂（Ｅ）と一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）との反応生成物（樹脂組成物）を主成分とし、これに必要に応じて硬化剤、非クロム系防錆添加剤、固形潤滑剤などが添加されるが、さらに必要に応じて、添加剤として、有機着色顔料（例えば、縮合多環系有機顔料、フタロシアニン系有機顔料など）、着色染料（例えば、有機溶剤可溶性アゾ系染料、水溶性アゾ系金属染料など）、無機顔料（例えば、酸化チタンなど）、キレート剤（例えば、チオールなど）、導電性顔料（例えば、亜鉛、アルミニウム、ニッケルなどの金属粉末、リン化鉄、アンチモンドープ型酸化錫など）、カップリング剤（例えば、シランカップリング剤、チタンカップリング剤など）、メラミン・シアヌル酸付加物などの１種又は２種以上を添加することができる。
【０１２６】
また、上記主成分および添加成分を含む皮膜形成用の塗料組成物は、通常、溶媒（有機溶剤および／または水）を含有し、さらに必要に応じて中和剤などが添加される。
上記有機溶剤としては、上記皮膜形成有機樹脂（Ｅ）と活性水素含有化合物（Ｆ）との反応生成物を溶解または分散でき、塗料組成物として調整できるものであれば特別な制約なく、例えば、先に例示した種々の有機溶剤を使用することができる。
上記中和剤は、皮膜形成有機樹脂（Ｅ）を中和して水性化するために必要に応じて配合されるものであり、皮膜形成有機樹脂（Ｅ）がカチオン性樹脂である場合には酢酸、乳酸、蟻酸などの酸を中和剤として使用することができる。
上層皮膜の乾燥膜厚は０．５〜２．０μｍ、好ましくは０．５〜１．５μｍとする。上層皮膜の膜圧が０．５μｍ未満では耐食性が不十分であり、一方、膜厚が２．０μｍを超えると溶接性や電着塗装性が低下する。
また、溶接性や電着塗装性の観点からは、第一層の表面処理皮膜と第二層の上層皮膜の合計膜厚は２．０μｍ以下であることが好ましい。
【０１２７】
次に、本発明の表面処理鋼板の製造方法について説明する。
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には、上述した組成を有する表面処理組成物（処理液）を乾燥皮膜厚が上記範囲となるようにめっき鋼板面に塗布し、水洗することなく加熱乾燥させる。
【０１２８】
表面処理組成物をめっき鋼板面に形成する方法としては、塗布法、浸漬法、スプレー法のいずれでもよい。塗布処理方法としては、ロールコーター（３ロール方式、２ロール方式など）、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、スクイズコーターなどによる塗布処理または浸漬処理、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。
【０１２９】
表面処理組成物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。加熱乾燥は到達板温で３０〜１５０℃、好ましくは４０℃〜１４０℃の範囲で行うことが望ましい。この加熱乾燥温度が３０℃未満では皮膜中に水分が多量に残り、耐食性が不十分となる。また、加熱乾燥温度が１５０℃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。また、加熱乾燥温度が１５０℃を超えるとＢＨ鋼板に適用できなくなるため好ましくない。
上記のようにして形成された表面処理皮膜の上層には、第二層皮膜として上層皮膜（有機樹脂皮膜）を形成する。第二層皮膜用の塗料組成物を上述した膜厚となるよう上記表面処理皮膜面に塗布し、加熱乾燥させる。塗料組成物の塗布は、上述した表面処理皮膜の形成に用いた方法に準じて行えばよい。
【０１３０】
塗料組成物の塗布後、通常は水洗することなく、加熱乾燥を行うが、塗料組成物の塗布後に水洗工程を実施しても構わない。加熱乾燥処理には、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。加熱乾燥は到達板温で３０〜１５０℃、好ましくは４０℃〜１４０℃の範囲で行うことが望ましい。この加熱乾燥温度が３０℃未満では皮膜中に水分が多量に残り、耐食性が不十分となる。また、加熱乾燥温度が１５０℃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。また、加熱乾燥温度が１５０℃を超えるとＢＨ鋼板に適用できなくなるため好ましくない。
【０１３１】
したがって、本発明の表面処理鋼板の製造方法およびその好ましい実施形態は以下のとおりである。
［１］ 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、下記成分（ａ）〜（ｃ）を含有する表面処理組成物を塗布し、到達板温が３０〜１５０℃の温度で乾燥することにより皮膜厚が０．０１〜１．０μｍの表面処理皮膜を形成し、
（ａ）数平均分子量４００〜２００００のポリアルキレングリコール、ビスフェノール型エポキシ樹脂、活性水素含有化合物及びポリイソシアネート化合物を反応させて得られたポリアルキレングリコール変性エポキシ樹脂（Ａ）と、該ポリアルキレングリコール変性エポキシ樹脂（Ａ）以外のエポキシ基含有樹脂（Ｂ）と、活性水素を有するヒドラジン誘導体（Ｃ）とを反応させて得られた樹脂を水に分散させてなる水性エポキシ樹脂分散液
（ｂ）シランカップリング剤：前記水性エポキシ樹脂分散液の固形分１００質量部に対して１〜３００質量部
（ｃ）リン酸および／またはヘキサフルオロ金属酸：前記水性エポキシ樹脂分散液の固形分１００質量部に対して０．１〜８０質量部
その上層に、樹脂組成物の主成分が、皮膜形成有機樹脂（Ｅ）と一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）との反応生成物からなる塗料組成物を塗布し、到達板温が３０〜１５０℃の温度で乾燥することにより皮膜厚が０．５〜２．０μｍの上層皮膜を形成することを特徴とする高耐食性表面処理鋼板の製造方法。
【０１３２】
［２］ 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、下記成分（ａ）〜（ｃ）を含有する表面処理組成物を塗布し、到達板温が３０〜１５０℃の温度で乾燥することにより皮膜厚が０．０１〜１．０μｍの表面処理皮膜を形成し、
（ａ）数平均分子量４００〜２００００のポリアルキレングリコール、ビスフェノール型エポキシ樹脂、活性水素含有化合物及びポリイソシアネート化合物を反応させて得られたポリアルキレングリコール変性エポキシ樹脂（Ａ）と、該ポリアルキレングリコール変性エポキシ樹脂（Ａ）以外のエポキシ基含有樹脂（Ｂ）と、活性水素を有するヒドラジン誘導体（Ｃ）と、該ヒドラジン誘導体（Ｃ）以外の活性水素含有化合物（Ｄ）とを反応させて得られた樹脂を水に分散させてなる水性エポキシ樹脂分散液
（ｂ）シランカップリング剤：前記水性エポキシ樹脂分散液の固形分１００質量部に対して１〜３００質量部
（ｃ）リン酸および／またはヘキサフルオロ金属酸：前記水性エポキシ樹脂分散液の固形分１００質量部に対して０．１〜８０質量部
その上層に、樹脂組成物の主成分が、皮膜形成有機樹脂（Ｅ）と一部または全部の化合物が活性水素を有するヒドラジン誘導体（Ｇ）からなる活性水素含有化合物（Ｆ）との反応生成物からなる塗料組成物を塗布し、到達板温が３０〜１５０℃の温度で乾燥することにより皮膜厚が０．５〜２．０μｍの上層皮膜を形成することを特徴とする高耐食性表面処理鋼板の製造方法。
【０１３３】
［３］ 上記［１］または［２］の製造方法において、成分（ａ）の水性エポキシ樹脂分散液を得るためのエポキシ基含有樹脂（Ｂ）が、エポキシ当量１５０〜５０００のビスフェノールＡ型エポキシ樹脂であり、その数平均分子量が１５００〜１００００であることを特徴とする高耐食性表面処理鋼板の製造方法。
［４］ 上記［１］〜［３］のいずれかの製造方法において、成分（ａ）の水性エポキシ樹脂分散液がさらに、水酸基と架橋する基を有する硬化剤を含有することを特徴とする高耐食性表面処理鋼板の製造方法。
［５］ 上記［１］〜［４］のいずれかの製造方法において、表面処理皮膜形成用の表面処理組成物がさらに、水溶性リン酸塩を、成分（ａ）の水性エポキシ樹脂分散液の固形分１００質量部に対して固形分の割合で０．１〜６０質量部含有することを特徴とする高耐食性表面処理鋼板の製造方法。
【０１３４】
［６］ 上記［５］の製造方法において、表面処理皮膜形成用の表面処理組成物が水溶性リン酸塩として、カチオン成分とＰ_２Ｏ_５成分のモル比［カチオン］／［Ｐ_２Ｏ_５］が０．４〜１．０であって、且つカチオン種がＭｎ、Ｍｇ、Ａｌ、Ｎｉの中から選ばれる１種以上である水溶性リン酸塩を含有することを特徴とする高耐食性表面処理鋼板の製造方法。
［７］ 上記［１］〜［６］のいずれかの製造方法において、表面処理皮膜形成用の表面処理組成物がさらに、非クロム系防錆添加剤を、成分（ａ）の水性エポキシ樹脂分散液の固形分１００質量部に対して固形分の割合で０．１〜５０質量部含有することを特徴とする高耐食性表面処理鋼板の製造方法。
［８］ 上記［１］〜［７］のいずれかの製造方法において、上層皮膜形成用の塗料組成物がさらに、非クロム系防錆添加剤を、樹脂組成物の固形分１００質量部に対して固形分の割合で０．１〜５０質量部含有することを特徴とする高耐食性表面処理鋼板の製造方法。
【０１３５】
［９］ 上記［７］または［８］の製造方法において、表面処理皮膜形成用の表面処理組成物および／または上層皮膜形成用の塗料組成物が、非クロム系防錆添加剤として、下記（ｅ１）〜（ｅ５）の中から選ばれる１つ以上の防錆添加剤を含有することを特徴とする高耐食性表面処理鋼板の製造方法。
（ｅ１）酸化ケイ素
（ｅ２）カルシウムおよび／またはカルシウム化合物
（ｅ３）難溶性リン酸化合物
（ｅ４）モリブデン酸化合物
（ｅ５）トリアゾール類、チオール類、チアジアゾール類、チアゾール類、チウラム類の中から選ばれる１種以上の、Ｓ原子を含有する有機化合物
［１０］ 上記［１］〜［９］のいずれかの製造方法において、成分（ｂ）のシランカップリング剤として、反応性官能基としてアミノ基を有するシランカップリング剤の少なくとも１種を含有することを特徴とする高耐食性表面処理鋼板の製造方法。
［１１］ 上記［１］〜［１０］のいずれかの製造方法において、上層皮膜形成用の塗料組成物がさらに、固形潤滑剤を、樹脂組成物の固形分１００質量部に対して固形分の割合で１〜３０質量部含有することを特徴とする高耐食性表面処理鋼板の製造方法。
【０１３６】
なお、上述した表面処理皮膜及び上層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態の組み合わせとしては、例えば、表面処理皮膜＋上層皮膜／無処理、表面処理皮膜＋上層皮膜／表面処理皮膜、表面処理皮膜＋上層皮膜／表面処理皮膜＋上層皮膜など、任意の形態とすることができる。
【０１３７】
【実施例】
［実施例１］
第一層形成用の表面処理組成物は、樹脂組成物として表２に示す水溶性または水分散性エポキシ樹脂を用い、これにシランカップリング剤（表３）、リン酸又はヘキサフルオロ金属酸（表４）、水溶性リン酸塩（表５）、非クロム系防錆添加剤（表６）を適宜配合し、塗料用分散機（サンドグラインダー）を用いて所定時間攪拌し、表面処理組成物を調製した。
表２に示す水溶性または水分散性エポキシ樹脂は以下のようにして製造した。
・ポリアルキレングリコール変性エポキシ樹脂の製造
＜製造例１＞
温度計、撹拌機、冷却管を備えたガラス製四つ口フラスコに、数平均分子量４０００のポリエチレングリコール１６８８ｇとメチルエチルケトン５３９ｇ加え、６０℃で撹拌混合し均一透明になった後、トリレンジイソシアネート１７１ｇを加え、２時間反応させた後、エピコート８３４Ｘ９０（エポキシ樹脂，シェルジャパン社製、エポキシ当量２５０）１１２１ｇ、ジエチレングリコーリエチルエーテル６６ｇおよび１％ジブチルチンジラウレート溶液１．１ｇを添加し、さらに２時間反応させた。その後８０℃まで昇温し、３時間反応させてイソシアネート価が０．６以下になったことを確認した。その後９０℃まで昇温し、減圧蒸留により固形分濃度が８１．７％になるまでメチルエチルケトンを除去した。除去後、プロピレングリコールモノメチルエーテル６５９ｇ、脱イオン水２７０ｇを加えて希釈し、固形分濃度７６％のポリアルキレングリコール変性エポキシ樹脂溶液Ａ１を得た。
【０１３８】
・水性エポキシ樹脂分散液の製造
＜製造例２＞
ＥＰ１００４（エポキシ樹脂，油化シェルエポキシ社製，エポキシ当量１０００）２０２９ｇとプロピレングリコールモノブチルエーテル６９７ｇを四つ口フラスコに仕込み、１１０℃まで昇温して１時間で完全にエポキシ樹脂を溶解した。このものに、製造例１で得たポリアルキレングリコール変性エポキシ樹脂溶液Ａ１を１１８０ｇおよび３−アミノ−１，２，４−トリアゾール（分子量８４）３１１．７ｇ加えて１００℃で５時間反応させた後、プロピレングリコールモノブチルエーテル７１９．６ｇを加えて樹脂溶液Ｄ１を得た。
上記樹脂溶液Ｄ１を２５７．６ｇにＭＦ−Ｋ６０Ｘ（イソシアネート硬化剤，旭化成工業社製）５０ｇおよびＳｃａｔ２４（硬化触媒）０．３ｇを混合し、よく攪拌した後、水６９２．１ｇを少しずつ滴下・混合撹拌し、水性エポキシ樹脂分散液Ｅ１を得た。
【０１３９】
＜製造例３＞（ヒドラジン誘導体を含有しない水性エポキシ樹脂分散液）
ＥＰ１００４（エポキシ樹脂，油化シェルエポキシ社製，エポキシ当量１０００）２０２９ｇとプロピレングリコールモノブチルエーテル６９７ｇを四つ口フラスコに仕込み、１１０℃まで昇温して１時間で完全にエポキシ樹脂を溶解した。このものに、製造例１で得たポリアルキレングリコール変性エポキシ樹脂溶液Ａ１を１１８０ｇおよびプロピレングリコールモノブチルエーテル５２７．０ｇを加えて樹脂溶液Ｄ２を得た。
上記樹脂溶液Ｄ２を２５７．６ｇにＭＦ−Ｋ６０Ｘ（イソシアネート硬化剤，旭化成工業社製）５０ｇおよびＳｃａｔ２４（硬化触媒）０．３ｇを混合しよく攪拌した後、水６９２．１ｇを少しずつ滴下・混合撹拌し、水性エポキシ樹脂分散液Ｅ２を得た。
【０１４０】
第二層形成用の塗料組成物は、樹脂組成物として表７に示すものを用い、これに非クロム系防錆添加剤（表６）、固形潤滑剤（表８）を適宜配合し、塗料用分散機（サンドグラインダー）を用いて所定時間攪拌し、塗料組成物を調製した。表７に示す樹脂組成物の基体樹脂（反応生成物）は以下のようにして合成した。
＜合成例１＞
ＥＰ８２８（油化シェルエポキシ社製，エポキシ当量１８７）１８７０部とビスフェノールＡ９１２部、テトラエチルアンモニウムブロマイド２部、メチルイソブチルケトン３００部を四つ口フラスコに仕込み、１４０℃まで昇温して４時間反応させ、エポキシ当量１３９１、固形分９０％のエポキシ樹脂を得た。このものに、エチレングリコールモノブチルエーテル１５００部を加えてから１００℃に冷却し、３，５−ジメチルピラゾール（分子量９６）を９６部とジブチルアミン（分子量１２９）を１２９部加えて、エポキシ基が消失するまで６時間反応させた後、冷却しながらメチルイソブチルケトン２０５部を加えて、固形分６０％のピラゾール変性エポキシ樹脂を得た。これを樹脂組成物（１）とする。この樹脂組成物（１）は、皮膜形成有機樹脂（Ｅ）と、活性水素を有するヒドラジン誘導体（Ｇ）を５０ｍｏｌ％含む活性水素含有化合物との反応生成物である。
【０１４１】
＜合成例２＞
ＥＰ１００７（油化シェルエポキシ社製，エポキシ当量２０００）４０００部とエチレングリコールモノブチルエーテル２２３９部を四つ口フラスコに仕込み、１２０℃まで昇温して１時間で完全にエポキシ樹脂を溶解した。このものを１００℃に冷却し、３−アミノ−１，２，４−トリアゾール（分子量８４）を１６８部加えて、エポキシ基が消失するまで６時間反応させた後、冷却しながらメチルイソブチルケトン５４０部を加えて、固形分６０％のトリアゾール変成エポキシ樹脂を得た。これを樹脂組成物（２）とする。この樹脂組成物（２）は、皮膜形成有機樹脂（Ｅ）と、活性水素を有するヒドラジン誘導体（Ｇ）を１００ｍｏｌ％含む活性水素含有化合物との反応生成物である。
【０１４２】
＜合成例３＞
イソホロンジイソシアネート（イソシアネート当量１１１）２２２部とメチルイソブチルケトン３４部を四つ口フラスコに仕込み、３０〜４０℃に保ってメチルエチルケトキシム（分子量８７）８７部を３時間かけて滴下後、４０℃に２時間保ち、イソシアネート当量３０９、固形分９０％の部分ブロックイソシアネートを得た。
次いで、ＥＰ８２８（油化シェルエポキシ社製、エポキシ当量１８７）１４９６部とビスフェノールＡ６８４部、テトラエチルアンモニウムブロマイド１部、メチルイソブチルケトン２４１部を四つ口フラスコに仕込み、１４０℃まで昇温して４時間反応させ、エポキシ当量１０９０、固形分９０％のエポキシ樹脂を得た。このものに、メチルイソブチルケトン１０００部を加えてから１００℃に冷却し、３−メルカプト−１，２，４−トリアゾール（分子量１０１）を２０２部加えて、エポキシ基が消失するまで６時間反応させた後、上記固形分９０％の部分ブロックイソシアネートを２３０部加え１００℃で３時間反応させ、イソシアネート基が消失したことを確認した。さらに、エチレングリコールモノブチルエーテル４６１部を加えて、固形分６０％のトリアゾール変成エポキシ樹脂を得た。これを樹脂組成物（３）とする。この樹脂組成物（３）は、皮膜形成有機樹脂（Ｅ）と、活性水素を有するヒドラジン誘導体（Ｇ）を１００ｍｏｌ％含む活性水素含有化合物との反応生成物である。
【０１４３】
＜合成例４＞
ＥＰ８２８（油化シェルエポキシ社製、エポキシ当量１８７）１８７０部とビスフェノールＡ９１２部、テトラエチルアンモニウムブロマイド２部、メチルイソブチルケトン３００部を四つ口フラスコに仕込み、１４０℃まで昇温して４時間反応させ、エポキシ当量１３９１、固形分９０％のエポキシ樹脂を得た。このものに、エチレングリコールモノブチルエーテル１５００部を加えてから１００℃に冷却し、ジブチルアミン（分子量１２９）を２５８部加えて、エポキシ基が消失するまで６時間反応させた後、冷却しながらメチルイソブチルケトン２２５部を加えて、固形分６０％のエポキシアミン付加物を得た。これを樹脂組成物（４）とする。この樹脂組成物（４）は、皮膜形成有機樹脂（Ｅ）と、活性水素を有するヒドラジン誘導体（Ｇ）を含まない活性水素含有化合物との反応生成物である。
【０１４４】
冷延鋼板をベースとした家電、建材、自動車部品用のめっき鋼板である、表１に示すめっき鋼板を処理原板として用いた。なお、鋼板の板厚は評価の目的に応じて所定の板厚のものを採用した。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、上記第一層形成用の表面処理組成物をロールコーターにより塗布し、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。
次いで、上記第二層形成用の塗料組成物をロールコーターにより塗布し、各種温度で加熱乾燥した。皮膜の膜厚は、塗料組成物の固形分（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。
【０１４５】
得られた表面処理鋼板の皮膜組成と品質性能（耐食性、加工後耐食性、溶接性、電着塗装性）を評価した結果を表９〜表２２に示す。なお、品質性能の評価は以下のようにして行った。
（１）耐食性
各サンプルについて、下記の複合サイクル試験（ＣＣＴ）を施し、３０サイクル経過後の白錆発生面積率および赤錆発生面積率で評価した。
塩水噴霧（ＪＩＳ Ｚ ２３７１に基づく）：４時間
↓
乾燥（６０℃）：２時間
↓
湿潤（５０℃、９５％ＲＨ）：２時間
その評価基準は以下の通りである。
◎ ：白錆発生面積率１０％未満
○ ：白錆発生面積率１０％以上、３０％未満
○−：白錆発生面積率３０％以上で赤錆発生なし
△ ：赤錆発生ありで、赤錆発生面積率１０％未満
× ：赤錆発生面積率１０％以上
【０１４６】
（２）加工後耐食性
各サンプルに対して、下記の条件によるドロービードで変形と摺動を付加し、このサンプルを日本パーカライジング（株）製「ＦＣ−４４６０」を用いて、４５℃、２分間の条件で脱脂した後、前記「（１）耐食性」で行ったＣＣＴを施し、１８サイクル経過後の白錆発生面積率および赤錆発生面積率で評価した。
押付荷重：８００ｋｇｆ
引抜速度：１０００ｍｍ／ｍｉｎ
ビード肩Ｒ：オス側５ｍｍＲ，メス側５ｍｍＲ
押し込み深さ：７ｍｍ
使用油：プレトンＲ−３５２Ｌ
その評価基準は以下の通りである。
◎ ：白錆発生面積率１０％未満
○ ：白錆発生面積率１０％以上、３０％未満
○−：白錆発生面積率３０％以上で、赤錆発生なし
△ ：赤錆発生ありで、赤錆発生面積率１０％未満
× ：赤錆発生面積率１０％以上
【０１４７】
（３）溶接性
各サンプルについて、使用電極：ＣＦ型Ｃｒ−Ｃｕ電極、加圧力：２００ｋｇｆ、通電時間：１０サイクル／５０Ｈｚ、溶接電流：１０ｋＡの条件で連続打点性の溶接試験を行い、連続打点数で評価した。その評価基準は以下の通りである。
◎ ：２０００点以上
○ ：１０００点以上、２０００点未満
△ ：５００点以上、１０００点未満
× ：５００点未満
（４）電着塗装性
各サンプルにカチオン系電着塗料（関西ペイント（株）製「ＧＴ−１０」）を膜厚３０μｍとなるように塗装した後、１３０℃×３０分の焼付を行った。塗装したサンプルを沸水中に２時間浸漬し、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。その評価基準は以下の通りである。
◎ ：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
【０１４８】
【表１】

【０１４９】
【表２】

【０１５０】
【表３】

【０１５１】
【表４】

【０１５２】
【表５】

【０１５３】
【表６】

【０１５４】
【表７】

【０１５５】
【表８】

【０１５６】
なお、表９〜表２２中に記載の＊１〜＊１０は以下の内容を指す。
＊１：表１に記載のＮｏ．（めっき鋼板）
＊２：表２に記載のＮｏ．（水溶性または水分散性エポキシ樹脂）
＊３：表３に記載のＮｏ．（シランカップリング剤）
＊４：表４に記載のＮｏ．（リン酸またはヘキサフルオロ金属酸）
＊５：表５に記載のＮｏ．（水溶性リン酸塩）
＊６：表６に記載のＮｏ．（防錆添加剤）
＊７：質量部（水溶性または水分散性エポキシ樹脂以外の成分については、水溶性または水分散性エポキシ樹脂の固形分１００質量部に対する質量部）
＊８：表７に記載のＮｏ．（樹脂組成物）
＊９：表８に記載のＮｏ．（固形潤滑剤）
＊１０：質量部（有機樹脂以外の成分については、有機樹脂の固形分１００質量部に対する質量部）
【０１５７】
【表９】

【０１５８】
【表１０】

【０１５９】
【表１１】

【０１６０】
【表１２】

【０１６１】
【表１３】

【０１６２】
【表１４】

【０１６３】
【表１５】

【０１６４】
【表１６】

【０１６５】
【表１７】

【０１６６】
【表１８】

【０１６７】
【表１９】

【０１６８】
【表２０】

【０１６９】
【表２１】

【０１７０】
【表２２】

【０１７１】
［実施例２］
第一層の表面処理皮膜用として、本発明例１〜３では、表２のＮｏ．１の水性エポキシ樹脂分散液に対して、表３のＮｏ．１のシランカップリング剤とリン酸を配合した表面処理組成物を用い、また、比較例では表２のＮｏ．１の水性エポキシ樹脂分散液のみからなる表面処理組成物を用いた。これら表面処理組成物を、表面をアルカリ脱脂処理、水洗乾燥した表１のＮｏ．１のめっき鋼板にロールコーターにより塗布し、１４０℃で加熱乾燥して０．５μｍの膜厚の表面処理皮膜を形成させた。次いで、第二層の上層皮膜用として、本発明例および比較例ともに［実施例１］のＮｏ．３（表１０）と同じ塗料組成物を用い、この塗料組成物を第一層である表面処理皮膜の上にロールコーターにより塗布し、１４０℃で加熱乾燥して１．５μｍの膜厚の上層皮膜を形成させた。
【０１７２】
得られた表面処理鋼板について、［実施例１］と同様の試験条件および評価基準で耐食性と加工後耐食性を評価した。その結果を、第一層および第二層の皮膜構成とともに表２３に示す。
・比較例
表２３の比較例は、第一層の表面処理皮膜が有機樹脂のバリア層のみからなるものであるため耐食性と加工後耐食性は不十分である。
図１に比較例が有する表面処理皮膜に相当する皮膜の皮膜断面電子顕微鏡写真（明視野像）を示す。なお、試料の作成および測定などは先に述べた条件で行った。
【０１７３】
・本発明例１
表２３の本発明例１は、比較例に較べて優れた耐食性と加工後耐食性を有している。
図２に本発明例１が有する表面処理皮膜に相当する皮膜の皮膜断面電子顕微鏡写真（明視野像）を、図３に同じく皮膜断面の組成分析結果（ライン分析：縦軸は原子濃度で表示。なお、Ｃ濃度は大半がオーバースケールとなるため記載を省略。後述する図５、図７についても同様）を、それぞれ示す。なお、試料の作成および測定などは先に述べた条件で行った（後述する図４〜図７についても同様）。これらによれば、下層部分がＰ、ＺｎおよびＯを含み且つＺｎとＰを等モル含んだ化合物層（非晶質化合物層）、上層部分が有機樹脂マトリックス層からなる表面処理皮膜が形成されていることが判る。電子回折パターンによると、上記化合物層は非晶質状である。なお、図３（後述する図５、図７についても同様）において、化合物層中のＺｎとＰが亜鉛めっき皮膜側で等モルからＺｎリッチ側に乖離するのは、電子ビームのプローブ径が有限の大きさを有するため（亜鉛めっき層そのものと化合物層が、化合物層／めっき層界面で同時にプローブ径内に含まれることによる影響）である。
【０１７４】
・本発明例２
表２３の本発明例２は、本発明例１に較べてさらに優れた耐食性と加工後耐食性を有している。
図４に本発明例２が有する表面処理皮膜に相当する皮膜の皮膜断面電子顕微鏡写真（明視野像。なお、図４中の矢印は析出化合物を示し、斜め破線は図５のライン分析位置に対応する）を、図５に同じく皮膜断面の組成分析結果（グラフ中の下向き矢印は析出化合物の位置に対応する）を、それぞれ示す。これらによれば、本発明例１と同様に、表面処理皮膜の下層部分にはＰ、ＺｎおよびＯを含み且つＺｎとＰを等モル含んだ化合物層（非晶質化合物層）が形成されている。さらに、この本発明例２では、表面処理皮膜中にＰ、ＺｎおよびＯを含む化合物が析出している。電子回折パターンによると、上記化合物層および析出化合物は非晶質状である。
【０１７５】
・本発明例３
表２３の本発明例３は、本発明例２に較べてさらに優れた耐食性と加工後耐食性を有している。
図６に本発明例３が有する表面処理皮膜に相当する皮膜の皮膜断面電子顕微鏡写真（明視野像。なお、図６中の矢印は析出化合物を示し、斜め破線は図７のライン分析位置に対応する）を、図７に同じく皮膜断面の組成分析結果（グラフ中の下向き矢印は析出化合物の位置に対応する）を、それぞれ示す。これらによれば、本発明例１，２と同様に、表面処理皮膜の下層部分にはＰ、ＺｎおよびＯを含み且つＺｎとＰを等モル含んだ化合物層（非晶質化合物層）が形成されている。さらに、この本発明例３では、表面処理皮膜中にＺｎ、Ｐ、ＳｉおよびＯを含む化合物が析出している。また、これらの析出化合物は、ＺｎとＰのモル比［Ｚｎ］／［Ｐ］が１．０未満である。電子回折パターンによると、上記化合物層および析出化合物は非晶質状である。
【０１７６】
【表２３】

【０１７７】
なお、表２３中に記載の＊１〜＊７は以下の内容を指す。
＊１：表２に記載のＮｏ．（水分散性エポキシ樹脂）
＊２：表３に記載のＮｏ．（シランカップリング剤）
＊３：表４に記載のＮｏ．（リン酸またはヘキサフルオロ金属酸）
＊４：質量部（水分散性エポキシ樹脂以外の成分については、水分散性エポキシ樹脂の固形分１００質量部に対する質量部）
＊５：表７に記載のＮｏ．（樹脂組成物）
＊６：表６に記載のＮｏ．（防錆添加剤）
＊７：質量部（防錆添加剤については、有機樹脂の固形分１００質量部に対する質量部）
【０１７８】
【発明の効果】
以上述べたように本発明の表面処理鋼板は、皮膜中にクロムを含まないにもかかわらず非常に優れた平板および加工後の耐食性を有し、しかも溶接性、塗装性にも優れている。このため本発明の表面処理鋼板は、自動車用途に特に有用である。
【図面の簡単な説明】
【図１】
［実施例２］における比較例の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面組織の電子顕微鏡拡大写真
【図２】
［実施例２］における本発明例１の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面組織の電子顕微鏡拡大写真
【図３】
［実施例２］における本発明例１の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面の組成分析結果を示すグラフ
【図４】
［実施例２］における本発明例２の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面組織の電子顕微鏡拡大写真
【図５】
［実施例２］における本発明例２の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面の組成分析結果を示すグラフ
【図６】
［実施例２］における本発明例３の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面組織の電子顕微鏡拡大写真
【図７】
［実施例２］における本発明例３の表面処理鋼板について、その表面処理皮膜に相当する皮膜の皮膜断面の組成分析結果を示すグラフ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a surface-treated steel sheet most suitable for use in automobiles, home appliances, and building materials, and more particularly to an environment-adaptive surface-treated steel sheet containing no chromium at the time of production of the surface-treated steel sheet and in the surface treatment film, and a method for producing the same. It is.
[0002]
[Prior art]
Conventionally, steel sheets for home appliances, building materials, and automobiles have been made of chromic acid, heavy steel for the purpose of improving corrosion resistance (white rust resistance, red rust resistance) on the surface of zinc-based or aluminum-based steel sheets. BACKGROUND ART Steel sheets that have been subjected to chromate treatment with a treatment liquid containing chromic acid or a salt thereof as a main component are widely used. This chromate treatment is an economical treatment method that has excellent corrosion resistance and can be performed relatively easily.
[0003]
Chromate treatment uses hexavalent chromium, which is a pollution control substance, and this hexavalent chromium is treated in a closed system in the treatment process, is completely reduced and recovered, and is not released to nature. Since the elution of chromium from the chromate film can be made almost zero by the sealing action of the organic film, the environment and the human body are not substantially contaminated by hexavalent chromium. However, due to recent global environmental problems, there is a growing movement to voluntarily reduce the use of heavy metals including hexavalent chromium. Further, in order to prevent the environment from being polluted when dumping shredder dust of waste products, there has been a movement to reduce or eliminate heavy metals in products as much as possible.
[0004]
For this reason, in order to prevent the generation of white rust on the galvanized steel sheet, many processing techniques that do not rely on chromate treatment, so-called chrome-free techniques, have been proposed. For example, there is a method of using an inorganic compound, an organic compound, an organic polymer material, or a solution obtained by combining them to form a thin film by a method such as immersion, coating, or electrolytic treatment.
[0005]
Specifically, the following methods can be cited as conventional techniques.
(1) A method of forming a film by immersing or applying a treatment solution in which a polyhydric phenol carboxylic acid such as tannic acid and a silane coupling agent are blended (for example, Patent Documents 1 and 2)
(2) A method of forming a film using a treatment solution in which a polyhydric phenolcarboxylic acid such as tannic acid or a phosphoric acid compound is blended with an organic resin (for example, Patent Documents 3 to 6)
(3) A method of applying a film in which an organic resin and a silane coupling agent are blended (for example, Patent Documents 7 to 13)
[0006]
[Patent Document 1]
JP-A-7-216268
[Patent Document 2]
Japanese Patent No. 2968959
[Patent Document 3]
JP-A-8-325760
[Patent Document 4]
JP-A-2000-34578
[Patent Document 5]
JP 2000-199076 A
[Patent Document 6]
JP 2000-248380 A
[Patent Document 7]
JP-A-11-106945
[Patent Document 8]
JP 2000-319787 A
[Patent Document 9]
JP 2000-248384 A
[Patent Document 10]
JP-A-2000-178761
[Patent Document 11]
JP 2000-199076 A
[Patent Document 12]
JP 2000-281946 A
[Patent Document 13]
JP 2000-14443 A
[0007]
[Problems to be solved by the invention]
As the method (1), there is a method of treating with an aqueous solution containing a polyhydric phenolcarboxylic acid and a silane coupling agent, and further, a metal ion. One of the methods is a method shown in Patent Document 1 or the like. . However, this treatment method has a disadvantage that, although good adhesion can be obtained, sufficient corrosion resistance cannot be obtained.
As the method (2), for example, Patent Literature 3 discloses a method in which a treatment is performed with a treatment liquid containing a polyhydric phenol carboxylic acid, an organic resin, and metal ions. Further, Patent Document 4 discloses a method of immersing in a treatment liquid containing an organic resin and a phosphoric acid compound or applying the treatment liquid, followed by drying. However, although the protective film formed by these treatment liquids contributes to the improvement of corrosion resistance to some extent, it cannot provide a high degree of corrosion resistance as in the case of chromate treatment.
[0008]
As the method (3), for example, Patent Documents 8 and 9 disclose methods having a film containing an organic resin and a silane coupling agent, as well as a thiocarbonyl compound, a phosphoric acid compound, and a vanadium compound. However, the corrosion resistance is not sufficient because the organic resin is a polyurethane or acrylic olefin resin. Patent Document 11 discloses a resin having a film made of an acid-modified epoxy resin, while Patent Document 10 discloses a resin containing a monomer containing a hydroxyl group, a carboxyl group, a glycidyl group, and a phosphoric acid group as a copolymer component, a silane coupling agent, Disclosed are those having a film containing a phosphoric acid compound, but also have insufficient corrosion resistance. Patent Literature 7 discloses a film having a film in which a polyvinylphenol derivative is mixed with an etching agent such as a silane coupling agent and phosphoric acid, but also does not provide sufficient corrosion resistance. Patent Document 12 discloses a film having a film in which an etching agent is blended with an organic resin, and Patent Document 13 discloses a film having a film in which a silane coupling agent is blended in an organic resin. There is no description and the corrosion resistance is insufficient.
Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a surface-treated steel sheet which does not contain chromium in a film and has excellent corrosion resistance.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present inventors have conducted the following study on the principle of corrosion suppression for suppressing corrosion of a plated steel sheet.
Corrosion of the galvanized steel sheet having the surface treatment film proceeds in the following process.
(1) Corrosion factors (oxygen, water, chlorine ions, etc.) penetrate into the surface treatment film and diffuse into the plating film / surface treatment film interface.
(2) At the plating film / surface treatment film interface, zinc is dissolved by the following oxidation-reduction reaction.
Cathode reaction: 2H₂O + O₂+ 4e⁻  → 4OH⁻
Anode reaction: 2Zn → 2Zn²⁺+ 4e⁻
[0010]
Therefore, in order to improve the corrosion resistance of the galvanized steel sheet, it is indispensable to suppress the progress of both the reactions (1) and (2).
(1) Advanced barrier layer serving as a diffusion barrier for corrosion factors (mainly acts to suppress the cathode reaction)
(2) Reaction layer with plating metal that inactivates the surface layer of plating film (mainly acts to suppress the above-mentioned anodic reaction)
It is most effective to have a coating composition having the following formula, and more preferably, a coating composition in which a self-repair action is performed when a defect occurs in the reaction layer.
[0011]
The present inventor has proposed such a film configuration not as a two-layer film formed by separately coating the barrier layer forming component and the reaction layer forming component as in the prior art, but as a single layer formed by one coating. To be realized in the layer film, specifically, the barrier layer (1) described above (organic resin matrix layer described later) is formed on the upper portion of the film, and the reaction layer (amorphous compound described later) is formed on the lower portion of the film. Layers), and more preferably, by depositing a substance that causes a self-repairing action in the coating, it has been found that a remarkable effect of improving corrosion resistance can be obtained by a synergistic effect of these. When such a single-layer film is defined as a pseudo-two-layer film, the barrier layer and the reaction layer constituting the pseudo-two-layer film are located between the two-layer film formed by conventional two-time coating. There is no clear interface. Rather, it is considered that by forming the two in a gradient composition, a high level of corrosion resistance improving effect that cannot be obtained by the conventional single-layer coating can be exhibited.
[0012]
As a result of intensive studies by the present inventors, the pseudo two-layer coating as described above is obtained by reacting a specific modified epoxy resin with a hydrazine derivative having active hydrogen, etc. It can be seen that a surface treatment composition containing a coupling agent and a specific acid component (phosphoric acid, hexafluorometallic acid, or the like) is applied to the surface of a zinc-based steel sheet or an aluminum-based steel sheet and dried. Was.
[0013]
It has been known that a silane coupling agent has a function of improving the adhesion between an inorganic compound and an organic compound, and it is possible to increase the adhesion between a plating metal and a water-dispersible resin. In contrast to the known effects of such a silane coupling agent, according to the present invention, the acid component contained in the surface treatment composition activates the plating film surface by etching, and the silane coupling agent reacts with the activated plating. It is considered that extremely excellent adhesion between the plated metal and the film-forming resin can be obtained by chemically bonding both the metal and the film-forming resin. In other words, the combined addition of the silane coupling agent and the specific acid component in the surface treatment composition significantly improves the adhesion between the plating metal and the film-forming resin as compared with the case where the silane coupling agent is added alone. It is considered that as a result, the progress of corrosion of the plated metal is effectively suppressed, and particularly excellent corrosion resistance is obtained.
[0014]
The mechanism by which the pseudo-two-layer film having the above-described film configuration is formed in the present invention is not necessarily clear, but the reaction between the acid component in the surface treatment composition and the plating film surface may be involved in the film formation. is there. On the other hand, the following effects involving the silane coupling agent are also considered. That is, since the silane coupling agent hydrolyzed in the aqueous solution has a silanol group (Si-OH), the hydrogen bonding adsorption action of the silane coupling agent on the plating metal surface activated by the acid component is promoted, and the plating is performed. The silane coupling agent is concentrated on the metal surface and then dried to cause a dehydration-condensation reaction to form a strong chemical bond, thereby inactivating the above-mentioned reaction layer (2) below the film (that is, inactivating the plating film surface layer). In addition to the formation of a reaction layer with the plating metal, a barrier layer of the above item (1) (that is, a high-level barrier layer serving as a diffusion barrier for a corrosion factor) is formed by the concentrated water-dispersible resin on the upper part of the film. There is a possibility that the mechanism. In addition, there is a possibility that the above-mentioned effects are caused in combination. Further, it is considered that a reaction product (compound) of the dissolved plating metal such as zinc and the acid component precipitates in the film in the process of forming the film as described above.
[0015]
Although the anti-corrosion mechanism of such a pseudo-two-layer coating is not necessarily clear, the individual anti-corrosion mechanism is as follows. A molecular film is formed, which suppresses the permeation of corrosion factors (oxygen, water, chloride ions, etc.) and effectively suppresses the cathodic reaction that causes corrosion. It also removes plating metal ions eluted by the corrosion reaction. The free hydrazine derivative in the film is trapped to form a stable insoluble chelate compound layer, and the reaction layer of (2) above effectively inactivates the anodic reaction which inactivates the plating film surface layer and causes corrosion. In addition, the precipitated compound deposited in the film is dissolved in a corrosive environment to generate an acid component (such as phosphate ions). Self-repair effect of capturing metal ions such as zinc ions eluted from the plating film (combining with metal ions to form an insoluble compound) is obtained. Furthermore, the silane coupling agent is activated by the acid component. It is thought to be able to form a highly adherent and dense film by binding firmly to the plating metal surface and suppressing the dissolution of the plating metal, and also by combining with the film-forming resin. Thus, it is considered that extremely excellent corrosion resistance (white rust resistance) is obtained.
[0016]
Further, it was found that by adding a water-soluble phosphate or a chromium-free rust-preventive additive to the surface treatment composition, more excellent corrosion resistance was obtained. This is because the water-soluble phosphate has a poorly soluble film that acts as a barrier to corrosion factors, as well as a phosphate component that captures the eluted plating metal ions, forming an insoluble compound with the plating metal ions. It is possible to do. Further, the chromium-free rust-preventive additive forms a protective film at the starting point of corrosion, so that more excellent anticorrosion performance can be obtained. In practice, these combined effects result in very good anticorrosion performance.
Further, in the present invention, a particularly high anticorrosion effect can be obtained by forming a high barrier coating mainly composed of a specific chelating resin as a second layer coating on the above-mentioned surface treatment coating.
[0017]
The present invention has been made based on such findings, and the features are as follows.
[1] A surface treatment composition containing the following components (a) to (c) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and the thickness of the film formed by drying is 0.01 to 100%. Form a 1.0 μm surface treatment film,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water.
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
(C) phosphoric acid and / or hexafluorometallic acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
In the upper layer, the main component of the resin composition is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A high corrosion-resistant surface-treated steel sheet comprising an upper layer film having a thickness of 0.5 to 2.0 μm.
[0018]
[2] The thickness of a film formed by applying a surface treatment composition containing the components (a) to (c) to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet and drying the coating is 0.01 to 1; To form a surface treatment film of 0.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified Obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A), a hydrazine derivative (C) having an active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C). Aqueous epoxy resin dispersion obtained by dispersing resin in water
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
(C) phosphoric acid and / or hexafluorometallic acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
In the upper layer, the main component of the resin composition is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A high corrosion-resistant surface-treated steel sheet comprising an upper layer film having a thickness of 0.5 to 2.0 μm.
[0019]
[3] In the surface-treated steel sheet according to [1] or [2], the epoxy group-containing resin (B) for obtaining the aqueous epoxy resin dispersion of the component (a) is a bisphenol A type epoxy having an epoxy equivalent of 150 to 5,000. A highly corrosion-resistant surface-treated steel sheet, which is a resin and has a number average molecular weight of 1500 to 10,000.
[4] The surface-treated steel sheet according to any one of [1] to [3], wherein the aqueous epoxy resin dispersion of the component (a) further contains a curing agent having a group that crosslinks with a hydroxyl group. High corrosion resistant surface treated steel sheet.
[0020]
[5] The surface-treated steel sheet according to any one of [1] to [4], wherein the surface-treated composition for forming a surface-treated film further comprises a water-soluble phosphate and an aqueous epoxy resin dispersion of the component (a). A highly corrosion-resistant surface-treated steel sheet characterized by containing 0.1 to 60 parts by mass of a solid content with respect to 100 parts by mass of a solid content of the above.
[6] The surface-treated steel sheet according to the above [5], wherein the surface-treated composition for forming a surface-treated film comprises a water-soluble phosphate containing a cationic component and P₂O₅Component molar ratio [cation] / [P₂O₅] Is 0.4 to 1.0, and the cationic species is at least one selected from Mn, Mg, Al and Ni. Treated steel sheet.
[0021]
[7] The surface-treated steel sheet according to any one of the above [1] to [6], wherein the surface-treated composition for forming a surface-treated film further comprises a non-chromium-based rust-preventive additive, and an aqueous epoxy resin of the component (a). A highly corrosion-resistant surface-treated steel sheet comprising 0.1 to 50 parts by mass of a solid content based on 100 parts by mass of a solid content of a dispersion.
[8] In the surface-treated steel sheet according to any one of the above [1] to [7], the upper layer coating further contains a non-chromium-based rust-preventive additive in a ratio of a solid content to a solid content of 100 parts by mass of the resin composition. A highly corrosion-resistant surface-treated steel sheet characterized by containing 0.1 to 50 parts by mass.
[0022]
[9] In the surface-treated steel sheet according to the above [7] or [8], the surface treatment composition for forming a surface treatment film and / or the upper layer film is a non-chromium-based rust-preventive additive as described in the following (e1) to (e5). A highly corrosion-resistant surface-treated steel sheet comprising one or more rust preventive additives selected from the group consisting of:
(E1) Silicon oxide
(E2) Calcium and / or calcium compound
(E3) Poorly soluble phosphate compound
(E4) Molybdate compound
(E5) One or more organic compounds containing an S atom selected from triazoles, thiols, thiadiazoles, thiazoles, and thiurams
[10] The surface-treated steel sheet according to any of [1] to [9], wherein the silane coupling agent of the component (b) contains at least one silane coupling agent having an amino group as a reactive functional group. High corrosion resistant surface treated steel sheet characterized by the following.
[11] In the surface-treated steel sheet according to any one of the above [1] to [10], the upper film further includes a solid lubricant in a ratio of 1 to 30 in terms of a solid content with respect to 100 parts by mass of a solid content of the resin composition. High corrosion resistance surface treated steel sheet characterized by containing by mass.
[0023]
[12] An amorphous compound layer containing (x) P, Zn or / and Al and O on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and (y) a number average present on the upper layer. A polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a molecular weight of 400 to 20,000, a bisphenol-type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified epoxy resin (A) Having a water-dispersible resin obtained by reacting an epoxy group-containing resin (B) other than the above with an hydrazine derivative (C) having active hydrogen as a matrix. 0.1 to 1.0 μm,
In the upper layer, the main component of the resin composition is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet comprising an upper layer film having a thickness of 0.5 to 2.0 μm.
[0024]
[13] A (x) amorphous compound layer containing P, Zn or / and Al and O on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and (y) a number average present on the upper layer. Polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a molecular weight of 400 to 20,000, a bisphenol-type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified epoxy resin (A) Water-dispersible resin obtained by reacting an epoxy group-containing resin (B) other than the above, a hydrazine derivative (C) having an active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C). Table consisting of an organic resin matrix layer serving as a matrix and having a film thickness of 0.01 to 1.0 μm. Has a surface treatment film,
In the upper layer, the main component of the resin composition is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet comprising an upper layer film having a thickness of 0.5 to 2.0 μm.
[0025]
[14] The surface-treated steel sheet according to the above [12] or [13], wherein the surface-treated film further contains a silane compound.
[15] The surface-treated steel sheet according to any one of [12] to [14], wherein the surface-treated film contains P, Zn or / and a precipitation compound containing Al and O. Treated steel sheet.
[16] The high corrosion resistance of the surface-treated steel sheet according to any one of the above [12] to [15], wherein the surface-treated film contains P, Zn or / and a precipitated compound containing Al, Si and O. Surface treated steel sheet.
[0026]
[17] The surface-treated steel sheet according to any one of [12] to [16], wherein the surface-treated steel sheet has a surface-treated film on a surface of a galvanized steel sheet and an upper layer film thereon. A high corrosion resistant surface treated steel sheet, wherein the molar ratio [Zn] / [P] of Zn and P in the porous compound layer is 0.9 to 1.4.
[18] The surface-treated steel sheet according to any one of the above [15] to [17], wherein the surface-treated steel sheet has a surface-treated film on the surface of a zinc-based plated steel sheet and an upper layer film thereon. A highly corrosion-resistant surface-treated steel sheet, wherein the molar ratio [Zn] / [P] of Zn and P in the precipitated compound contained in the film is from 0.9 to 1.4.
[0027]
[19] The surface-treated steel sheet according to any one of the above [15] to [17], wherein the surface-treated steel sheet has a surface-treated film on the surface of a galvanized steel sheet and an upper layer film thereon. A highly corrosion-resistant surface-treated steel sheet, wherein the molar ratio [Zn] / [P] of Zn and P in the precipitated compound contained in the film is less than 1.0.
[20] In the surface-treated steel sheet according to any one of the above [12] to [19], the surface-treated film further contains a non-chromium-based rust-preventive additive in a proportion of a solid content of 100 parts by mass of an organic resin solid content. A highly corrosion-resistant surface-treated steel sheet characterized by containing 0.1 to 50 parts by mass.
[21] In the surface-treated steel sheet according to any one of the above [12] to [20], the upper layer film further contains a non-chromium-based rust-preventive additive in a ratio of a solid content to a solid content of 100 parts by mass of the resin composition. A highly corrosion-resistant surface-treated steel sheet characterized by containing 0.1 to 50 parts by mass.
[0028]
[22] In the surface-treated steel sheet according to the above [20] or [21], the surface treatment film and / or the upper film is one selected from the following (e1) to (e5) as a non-chromium-based rust-preventive additive. A highly corrosion-resistant surface-treated steel sheet comprising the rust preventive additive described above. (E1) Silicon oxide
(E2) Calcium and / or calcium compound
(E3) Poorly soluble phosphate compound
(E4) Molybdate compound
(E5) One or more organic compounds containing an S atom selected from triazoles, thiols, thiadiazoles, thiazoles, and thiurams
[23] In the surface-treated steel sheet according to any one of the above [12] to [22], the upper film further includes a solid lubricant in a ratio of 1 to 30 in terms of a solid content based on 100 parts by mass of a solid content of the resin composition. High corrosion resistance surface treated steel sheet characterized by containing by mass.
[0029]
[24] Applying a surface treatment composition containing the following components (a) to (c) to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and drying at a temperature of the ultimate plate temperature of 30 to 150 ° C. To form a surface treatment film having a film thickness of 0.01 to 1.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol-type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water.
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
(C) phosphoric acid and / or hexafluorometallic acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
In the upper layer, the main component of the resin composition is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A high corrosion resistant surface-treated steel sheet, wherein an upper layer film having a film thickness of 0.5 to 2.0 μm is formed by applying a coating composition comprising Manufacturing method.
[0030]
[25] A surface treatment composition containing the following components (a) to (c) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and dried at a temperature of 30 to 150 ° C. at the reached sheet temperature. To form a surface treatment film having a film thickness of 0.01 to 1.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol-type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified Obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A), a hydrazine derivative (C) having an active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C). Aqueous epoxy resin dispersion obtained by dispersing resin in water
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
(C) phosphoric acid and / or hexafluorometallic acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
In the upper layer, the main component of the resin composition is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A high corrosion resistant surface-treated steel sheet characterized in that a coating thickness of 0.5 to 2.0 μm is formed by applying a coating composition comprising Production method.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the details of the present invention and the reasons for the limitation will be described.
The galvanized steel sheet serving as the base of the surface-treated steel sheet of the present invention includes a zinc-coated steel sheet, a Zn-Ni alloy-coated steel sheet, a Zn-Fe alloy-coated steel sheet (electroplated steel sheet, galvannealed steel sheet), Zn-Cr Alloy plated steel sheet, Zn-Mn alloy plated steel sheet, Zn-Co alloy plated steel sheet, Zn-Co-Cr alloy plated steel sheet, Zn-Cr-Ni alloy plated steel sheet, Zn-Cr-Fe alloy plated steel sheet, Zn-Al alloy plated Steel sheet (for example, Zn-5% Al alloy plated steel sheet, Zn-55% Al alloy plated steel sheet), Zn-Mg alloy plated steel sheet, Zn-Al-Mg plated steel sheet (for example, Zn-6% Al-3% Mg alloy Metal oxides, polymers, etc. are dispersed in the plated films of these plated steel sheets, Zn-11% Al-3% Mg alloy plated steel sheets) Lead-based composite plated steel sheet (for example, Zn-SiO₂Dispersion-plated steel sheet) can be used.
[0032]
Further, among the above-mentioned platings, a multi-layer plated steel sheet obtained by plating two or more layers of the same type or different types may be used.
Further, as the aluminum-based steel sheet as a base of the surface-treated steel sheet of the present invention, an aluminum-plated steel sheet, an Al—Si alloy-plated steel sheet, or the like can be used.
Further, as the plated steel sheet, a steel sheet surface may be preliminarily subjected to thin plating such as Ni, and the above-described various platings may be applied thereon.
As a plating method, any practicable method can be adopted among an electrolysis method (electrolysis in an aqueous solution or electrolysis in a non-aqueous solvent), a melting method, and a gas phase method.
Further, in order to prevent blackening of the plating, a trace element of about 1 to 2000 ppm of Ni, Co, Fe is deposited in the plating film, or an alkaline aqueous solution or an acidic aqueous solution containing Ni, Co, Fe on the plating film surface. These elements may be deposited by performing a surface conditioning treatment with an aqueous solution.
[0033]
Next, a surface treatment film formed as a first layer film on the surface of the zinc-based plated steel sheet or the aluminum-based plated steel sheet and a surface treatment composition for forming the film will be described.
In the surface-treated steel sheet of the present invention, the surface-treated film formed on the surface of the galvanized steel sheet or the aluminum-based steel sheet is coated with a surface treatment composition containing the following components (a) to (c) and dried. It is a surface treatment film formed by this. This surface treatment film does not contain any chromium.
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An epoxy group-containing resin (B) other than the epoxy resin (A), a hydrazine derivative (C) having an active hydrogen, and, if necessary, an active hydrogen-containing compound (D) other than the hydrazine derivative (C). Aqueous epoxy resin dispersion obtained by dispersing the resin obtained by the reaction in water
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
(C) phosphoric acid and / or hexafluorometallic acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
[0034]
First, the aqueous epoxy resin dispersion as the component (a) will be described.
This aqueous epoxy resin dispersion comprises a specific polyalkylene glycol-modified epoxy resin (A), an epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), and a hydrazine derivative (C ) And, if necessary, a resin obtained by reacting an active hydrogen-containing compound (D) other than the hydrazine derivative (C) with water to disperse the resin in water.
[0035]
The polyalkylene glycol-modified epoxy resin (A) is obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol-type epoxy resin, an active hydrogen-containing compound, and a polyisocyanate compound. .
As the polyalkylene glycol, for example, polyethylene glycol, polypropylene glycol, polybutylene glycol and the like can be used, and among them, polyethylene glycol is particularly preferable. The number average molecular weight of the polyalkylene glycol is suitably in the range of 400 to 20,000, preferably 500 to 10,000 from the viewpoint of the water dispersibility and storability of the obtained resin.
The bisphenol-type epoxy resin is a bisphenol-based compound having at least one epoxy group in one molecule. In particular, bisphenol-based epoxy resin is obtained by a condensation reaction between a bisphenol-based compound and epihalohydrin (eg, epichlorohydrin). Glycidyl ether is preferred because a film having excellent flexibility and corrosion resistance is easily obtained.
[0036]
Representative examples of bisphenol-based compounds that can be used for preparing a bisphenol-type epoxy resin include bis (4-hydroxyphenyl) -2,2-propane, bis (4-hydroxyphenyl) -1,1-ethane, and bis (4-hydroxyphenyl) -1,1-ethane. (4-hydroxyphenyl) -methane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylsulfone, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-3-t- (Butylphenyl) -2,2-propane and the like. Among the epoxy resins prepared using such bisphenol compounds, bisphenol A type epoxy resins are particularly suitable in that a film having excellent flexibility and anticorrosion properties can be obtained.
In addition, the bisphenol type epoxy resin generally has a number average molecular weight of about 310 to 10000, particularly preferably about 320 to 2,000 from the viewpoint of production stability at the time of producing the polyalkylene glycol-modified epoxy resin. Preferably, the epoxy equivalent is in the range of about 155 to 5000, particularly preferably about 160 to 1000.
[0037]
The active hydrogen-containing compound is used for blocking an isocyanate group in the polyalkylene glycol-modified epoxy resin (A). Typical examples thereof include monohydric alcohols such as methanol, ethanol, and diethylene glycol monobutyl ether; monovalent carboxylic acids such as acetic acid and propionic acid; and monovalent thiols such as ethyl mercaptan. Other blocking agents (active hydrogen-containing compounds) include secondary amines such as diethylamine; one secondary amino group or hydroxyl group such as diethylenetriamine and monoethanolamine and one or more primary amines. A compound obtained by modifying a primary amino group of an amine compound containing an amino group with a ketone, an aldehyde, or a carboxylic acid by heating at, for example, a temperature of 100 to 230 ° C. to form an aldimine, ketimine, oxazoline, or imidazoline; methyl ethyl ketoxime And phenols such as phenol and nonylphenol. It is preferred that these compounds generally have a number average molecular weight in the range of 30 to 2000, particularly preferably 30 to 200.
[0038]
The polyisocyanate compound is a compound having two or more, preferably two or three isocyanate groups in one molecule, and a compound generally used for producing a polyurethane resin can be used similarly. Such polyisocyanate compounds include aliphatic, alicyclic, and aromatic polyisocyanate compounds. Representative examples include aliphatic polyisocyanate compounds such as hexamethylene diisocyanate (HMDI), HMDI biuret compound and HMDI isocyanurate compound; isophorone diisocyanate (IPDI), IPDI biuret compound, and IPDI isocyanurate compound. Examples thereof include alicyclic polyisocyanate compounds such as hydrogenated xylylene diisocyanate and hydrogenated 4,4'-diphenylmethane diisocyanate; and aromatic polyisocyanate compounds such as tolylene diisocyanate and xylylene diisocyanate.
[0039]
In general, the proportion of each component at the time of production of the polyalkylene glycol-modified epoxy resin (A) is suitably within the following range.
That is, the equivalent ratio of the hydroxyl group of the polyalkylene glycol to the isocyanate group of the polyisocyanate compound is 1 / 1.2 to 1/10, preferably 1 / 1.5 to 1/5, particularly preferably 1 / 1.5 to 1. It is appropriate to set it to 1/3. The equivalent ratio of the hydroxyl group of the active hydrogen-containing compound to the isocyanate group of the polyisocyanate compound is 1/2 to 1/100, preferably 1/3 to 1/50, particularly preferably 1/3 to 1/20. Is appropriate. The equivalent ratio of the total amount of the hydroxyl groups of the polyalkylene glycol, the bisphenol-type epoxy resin and the active hydrogen-containing compound to the isocyanate group of the polyisocyanate compound is not more than 1 / 1.5, preferably 1 / 0.1 to 1/1. 0.5, particularly preferably 1 / 0.1 to 1 / 1.1.
[0040]
The reaction of the above polyalkylene glycol, bisphenol-type epoxy resin, active hydrogen-containing compound and polyisocyanate compound can be carried out by a known method.
The polyalkylene glycol-modified epoxy resin (A) obtained above, an epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), and a hydrazine derivative (C) having active hydrogen are further required. By reacting with an active hydrogen-containing compound (D) other than the hydrazine derivative (C) according to the above, an epoxy resin which can be easily dispersed in water and has good adhesion to a material can be obtained. .
[0041]
As the epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), a glycidyl group is introduced by reacting a polyphenol such as bisphenol A, bisphenol F, and novolak phenol with an epihalohydrin such as epichlorohydrin. Or an aromatic epoxy resin obtained by further reacting a polyphenol with the glycidyl group-introduced reaction product to increase the molecular weight; furthermore, an aliphatic epoxy resin, an alicyclic epoxy resin, and the like. One type may be used alone, or two or more types may be used in combination. It is preferable that these epoxy resins have a number average molecular weight of 1500 or more especially when a film-forming property at a low temperature is required.
Examples of the epoxy group-containing resin (B) include a resin obtained by reacting various modifiers with an epoxy group or a hydroxyl group in the epoxy group-containing resin. For example, an epoxy ester resin obtained by reacting a drying oil fatty acid is used. An epoxy acrylate resin modified with a polymerizable unsaturated monomer component containing acrylic acid or methacrylic acid; a urethane-modified epoxy resin reacted with an isocyanate compound.
[0042]
Further, as the epoxy group-containing resin (B), an unsaturated monomer having an epoxy group and a polymerizable unsaturated monomer component essentially including an acrylate or a methacrylate are prepared by a solution polymerization method, an emulsion polymerization method or a suspension polymerization method. An acrylic copolymer resin copolymerized with an epoxy group-containing monomer synthesized by the above method can be used. Examples of the polymerizable unsaturated monomer component include methyl (meth) acrylate, ethyl (meth) acrylate, and propyl ( Acrylic acid or methacrylic acid such as (meth) acrylate, n-, iso- or tert-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate; C1 to C24 Alkyl ester; acrylic acid, methacrylic acid, styrene, vinyltoluene, acrylamide, acrylonitrile, N-methylol (meth) acrylamide, C1-4 alkyl etherified product of N-methylol (meth) acrylamide; N, N-diethylaminoethyl methacrylate and the like. Can be mentioned. In addition, as the unsaturated monomer having an epoxy group, glycidyl methacrylate, glycidyl acrylate, 3,4 epoxycyclohexyl-1-methyl (meth) acrylate, and the like, as long as it has an epoxy group and a polymerizable unsaturated group, There is no restriction.
The acrylic copolymer resin may be a resin modified with a polyester resin, an epoxy resin, a phenol resin, or the like.
[0043]
Particularly preferred as the epoxy group-containing resin (B) is a resin represented by the following chemical structural formula, which is a reaction product of bisphenol A and epiparohydrin, and is particularly suitable because of its excellent corrosion resistance.
Embedded image

In the above chemical structural formula, q is an integer of 0 to 50, preferably an integer of 1 to 40, particularly preferably an integer of 2 to 20.
Such a bisphenol A type epoxy resin can be obtained by a production method widely known in the art.
[0044]
Examples of the active hydrogen-containing compound that reacts with the epoxy group of the epoxy group-containing resin (B) include the following.
.Hydrazine derivatives having active hydrogen
.Primary or secondary amine compounds having active hydrogen
・ Organic acids such as ammonia and carboxylic acid
・ Hydrogen halides such as hydrogen chloride
・ Alcohols, thiols
A quaternary chlorinating agent which is a mixture of a hydrazine derivative having no active hydrogen or a tertiary amine and an acid
When preparing the aqueous epoxy resin dispersion, one or more of these can be used. However, in order to obtain excellent corrosion resistance, at least a part (preferably, all) of the active hydrogen-containing compound has to be active. It must be a hydrazine derivative having hydrogen. That is, the hydrazine derivative (C) having an active hydrogen is an essential component, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C) is used as necessary.
[0045]
Representative examples of the amine compound having activated hydrogen include the following.
(1) The primary amino group of an amine compound containing one secondary amino group and one or more primary amino groups such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, and methylaminopropylamine is converted into a ketone, A compound modified with aldemine, ketimine, oxazoline or imidazoline by heat reaction with aldehyde or carboxylic acid at a temperature of, for example, about 100 to 230 ° C;
(2) Secondary monoamines such as diethylamine, diethanolamine, di-n- or -ios-propanolamine, N-methylethanolamine, N-ethylethanolamine;
[0046]
(3) a secondary amine-containing compound obtained by adding a monoalkanolamine such as monoethanolamine and dialkyl (meth) acrylamide by a Michael addition reaction;
(4) Compounds in which the primary amine group of an alkanolamine such as monoethanolamine, neopentanolamine, 2-aminopropanol, 3-aminopropanol, or 2-hydroxy-2 '(aminopropoxy) ethyl ether is modified to ketimine;
[0047]
The quaternary chlorinating agents that can be used as a part of the active hydrogen-containing compound are hydrazine derivatives having no active hydrogen or tertiary amines, which themselves have no reactivity with epoxy groups, and thus can react with epoxy groups. And a mixture with an acid. The quaternary chlorinating agent reacts with an epoxy group in the presence of water, if necessary, to form a quaternary salt with the epoxy group-containing resin. The acid used to obtain the quaternary chlorinating agent may be any of organic acids such as acetic acid and lactic acid and inorganic acids such as hydrochloric acid. Further, as a hydrazine derivative having no active hydrogen used for obtaining a quaternary chlorinating agent, for example, 3,6-dichloropyridazine and the like, and as a tertiary amine, for example, dimethylethanolamine, triethylamine, Trimethylamine, triisopropylamine, methyldiethanolamine and the like can be mentioned.
[0048]
A hydrazine derivative having active hydrogen is the most useful active hydrogen-containing compound and exhibits excellent performance in corrosion resistance.
Specific examples of the hydrazine derivative having active hydrogen include the following.
(1) Carbohydrazide, propionic hydrazide, salicylic hydrazide, adipic dihydrazide, sebacic dihydrazide, dodecanoic dihydrazide, isophthalic dihydrazide, thiocarbohydrazide, 4,4'-oxybisbenzenesulfonyl hydrazide, benzophenone polyhydramide, benzophenone polyhydramide Hydrazide compounds such as;
(2) pyrazole compounds such as pyrazole, 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone and 3-amino-5-methylpyrazole;
[0049]
(3) 1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5-amino -3-mercapto-1,2,4-triazole, 2,3-dihydro-3-oxo-1,2,4-triazole, 1H-benzotriazole, 1-hydroxybenzotriazole (monohydrate), 6- Triazole compounds such as methyl-8-hydroxytriazolopyridazine, 6-phenyl-8-hydroxytriazolopyridazine, 5-hydroxy-7-methyl-1,3,8-triazaindolizine;
[0050]
(4) tetrazole compounds such as 5-phenyl-1,2,3,4-tetrazole and 5-mercapto-1-phenyl-1,2,3,4-tetrazole;
(5) thiadiazole compounds such as 5-amino-2-mercapto-1,3,4-thiadiazole and 2,5-dimercapto-1,3,4-thiadiazole;
{Circle around (6)} Maleic hydrazide, 6-methyl-3-pyridazone, 4,5-dichloro-3-pyridazone, 4,5-dibromo-3-pyridazone, 6-methyl-4,5-dihydro-3-pyridazone and the like Pyridazine compounds;
Of these, pyrazole compounds and triazole compounds having a 5- or 6-membered ring structure and having a nitrogen atom in the ring structure are particularly preferred.
These hydrazine derivatives can be used alone or in combination of two or more.
[0051]
The polyalkylene glycol-modified epoxy resin (A) described above, an epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), and a hydrazine derivative (C) having active hydrogen, are further required. Is reacted with an active hydrogen-containing compound (D) other than the hydrazine derivative (C) at a temperature of preferably 10 to 300 ° C, more preferably 50 to 150 ° C for about 1 to 8 hours, thereby obtaining By dispersing the resin in water, the above-mentioned aqueous epoxy resin dispersion can be obtained.
[0052]
The above reaction may be carried out by adding an organic solvent, and the type of the organic solvent used is not particularly limited. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, dibutyl ketone, cyclohexanone; ethanol, butanol, 2-ethylhexyl alcohol, benzyl alcohol, ethylene glycol, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether Hydroxyl-containing alcohols and ethers such as propylene glycol, propylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether; esters such as ethyl acetate, butyl acetate, and ethylene glycol monobutyl ether acetate; toluene, xylene Such as aromatic hydrocarbons Indicates possible, it is possible to use one or more of these. Among them, ketone-based or ether-based solvents are particularly preferable from the viewpoints of solubility with an epoxy resin, film-forming properties, and the like.
[0053]
The mixing ratio of the polyalkylene glycol-modified epoxy resin (A), the epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), and the hydrazine derivative (C) having active hydrogen is determined by the polyalkylene glycol-modified epoxy resin. The equivalent ratio of the active hydrogen group in the hydrazine derivative (C) to the epoxy group in the epoxy resin (A) and the epoxy group-containing resin (B) is 0.01 to 10, preferably 0.1 to 8, and more preferably 0. 0.2 to 4 is appropriate from the viewpoints of corrosion resistance and water dispersibility of the resin.
Further, a part of the hydrazine derivative (C) having active hydrogen can be replaced by the active hydrogen-containing compound (D), but the replacement amount is 90 mol% or less, preferably 70 mol% or less, more preferably 10 to 10 mol%. It is suitable to be within the range of 60 mol% from the viewpoint of anticorrosion properties and adhesion.
[0054]
Further, in order to form a dense barrier film, it is desirable to mix a curing agent into the resin composition and heat-cur the film. The curing method for forming a film of the resin composition is selected from (1) a curing method utilizing a urethanization reaction between an isocyanate and a hydroxyl group in a base resin, and (2) melamine, urea and benzoguanamine. Etherification reaction between an alkyl etherified amino resin obtained by reacting a monohydric alcohol having 1 to 5 carbon atoms with a part or all of a methylol compound obtained by reacting at least one formaldehyde with a hydroxyl group in a base resin Is suitable, and among them, it is particularly preferable that the main reaction is a urethanization reaction between an isocyanate and a hydroxyl group in the base resin.
[0055]
The polyisocyanate compound as a curing agent that can be used in the curing method (1) is an aliphatic, alicyclic (including heterocyclic) or aromatic isocyanate compound having at least two isocyanate groups in one molecule. Or a compound obtained by partially reacting those compounds with a polyhydric alcohol. Examples of such a polyisocyanate compound include the following.
[0056]
(1) m- or p-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, o- or p-xylylene diisocyanate, hexamethylene diisocyanate, dimer acid diisocyanate, isophorone diisocyanate
{Circle around (2)} The compound of the above [1] alone or a mixture thereof and a polyhydric alcohol (a dihydric alcohol such as ethylene glycol and propylene glycol; a trihydric alcohol such as glycerin and trimethylolpropane; a tetrahydric alcohol such as pentaerythritol; A reaction product with at least two isocyanates in one molecule such as sorbitol and dihydric alcohol such as dipentaerythritol.
These polyisocyanate compounds can be used alone or in combination of two or more.
[0057]
Further, as a protective agent (blocking agent) for the polyisocyanate compound, for example,
(1) aliphatic monoalcohols such as methanol, ethanol, propanol, butanol and octyl alcohol;
{Circle around (2)} Monoethers of ethylene glycol and / or diethylene glycol, for example, monoethers such as methyl, ethyl, propyl (n-, iso) and butyl (n-, iso, sec);
(3) aromatic alcohols such as phenol and cresol;
(4) oximes such as acetoxime and methyl ethyl ketone oxime;
By reacting one or more of these with the polyisocyanate compound, a polyisocyanate compound that is stably protected at least at room temperature can be obtained.
[0058]
Such a polyisocyanate compound (a2) is used as a curing agent (a) / (a2) = 95/5 to 55/45 (non-volatile) with respect to the aqueous epoxy resin dispersion (a) (the component (a)). Mass ratio), preferably (a) / (a2) = 90/10 to 65/35. Polyisocyanate compounds have water absorbency, and if they are added in excess of (a) / (a2) = 55/45, the adhesion of the surface treatment film will be degraded. Further, the unreacted polyisocyanate compound moves into the upper layer coating, and causes curing inhibition and poor adhesion of the upper layer coating. From such a viewpoint, the blending amount of the polyisocyanate compound (a2) is preferably (a) / (a2) = 55/45 or less.
[0059]
The water-dispersible resin is sufficiently crosslinked by the addition of the above-mentioned crosslinking agent (curing agent). However, in order to further increase the low-temperature crosslinking property, it is desirable to use a known curing promoting catalyst. As the curing promoting catalyst, for example, N-ethylmorpholine, dibutyltin dilaurate, cobalt naphthenate, stannous chloride, zinc naphthenate, bismuth nitrate and the like can be used.
For the purpose of slightly improving the physical properties such as adhesion, a known resin such as acryl, alkyd, or polyester can be used in combination with the epoxy group-containing resin (B).
[0060]
The reaction product of the polyalkylene glycol-modified epoxy resin (A), the epoxy group-containing resin (B) and the hydrazine derivative (C) having an active hydrogen (and optionally the active hydrogen-containing compound (D)) is dispersed in water. For example, the following method can be adopted.
{Circle around (1)} A tertiary amine which is a neutralizing agent by reacting an epoxy group of an epoxy group-containing resin (that is, resins (A) and (B)) with a dibasic acid or a secondary amine which is an active hydrogen-containing compound. Neutralizing with acetic acid or phosphoric acid, and dispersing in water
(2) A method of dispersing in water using a modified epoxy resin obtained by reacting an epoxy resin with a polyalkylene oxide having a terminal hydroxyl group such as polyethylene glycol or polypropylene glycol with isocyanate as a dispersant.
(3) Method using both (1) and (2) above
[0061]
In the surface treatment composition, in addition to the specific water-dispersible resin described above, as other water-dispersible resins and / or water-soluble resins, for example, acrylic resins, urethane resins, polyester resins, epoxy resins, One or more of an ethylene-based resin, an alkyd-based resin, a phenolic resin, and an olefin resin may be blended with the upper limit of about 15 mass% in the total resin solid content.
[0062]
Next, the silane coupling agent as the component (b) will be described.
Examples of the silane coupling agent include vinylmethoxysilane, vinylethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, γ-glycid Xypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ -Aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methyl Tacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, p-styryltrimethoxysilane, γ -Acryloxypropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, γ-isocyanatepropyl Triethoxysilane, γ-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N- (vinylbenzylamine) -β-aminoethyl-γ-aminopropyltri Etc. can be mentioned Tokishishiran, these one may be used alone or in combination of two or more.
[0063]
In the present invention, the reason described above may be considered for improving the white rust resistance by including the silane coupling agent together with the specific acid component in the surface treatment composition.
Also, among the silane coupling agents, from the viewpoint of having a functional group having high reactivity with the water-dispersible resin of the component (a), a silane coupling agent having an amino group as a reactive functional group is particularly preferable. preferable. Examples of such a silane coupling agent include N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, and N-β (aminoethyl) γ -Aminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and the like. Specifically, “KBM-903” and “KBE-903” manufactured by Shin-Etsu Chemical Co., Ltd. , "KBM-603", "KBE-602", "KBE-603" (all of which are trade names) and the like.
[0064]
The amount of the silane coupling agent is from 1 to 300 parts by mass, preferably from 5 to 100 parts by mass, more preferably from 15 to 50 parts by mass, based on 100 parts by mass of the solid content of the aqueous epoxy resin dispersion as the component (a). It is appropriate to use parts by mass. If the amount of the silane coupling agent is less than 1 part by mass, the corrosion resistance is poor. On the other hand, if it exceeds 300 parts by mass, a sufficient film cannot be formed, so that the effect of enhancing the adhesion to the water-dispersible resin and the barrier property can be exhibited. And the corrosion resistance is reduced.
[0065]
Next, the phosphoric acid and / or hexafluorometallic acid as the component (c) acts on the inactive plating metal surface to activate the plating metal surface. The phosphoric acid and the hexafluorometallic acid may be used alone or in combination.
The type of hexafluorometallic acid is not particularly limited, but hexafluorometal containing at least one element selected from Ti, Si, and Zr such as fluorotitanic acid, zirconic fluoride, and hydrofluoric acid. Acids are preferred, and one or more of these can be used.
[0066]
The compounding amount of phosphoric acid and / or hexafluorometallic acid is 0.1 to 80 parts by mass in total, preferably 1 to 100 parts by mass, based on 100 parts by mass of the solid content of the aqueous epoxy resin dispersion as the component (a). The amount is suitably 60 parts by mass, more preferably 5 to 50 parts by mass. If the amount of phosphoric acid and / or hexafluorometallic acid is less than 0.1 part by mass, the corrosion resistance is inferior. On the other hand, if it exceeds 80 parts by mass, the soluble component of the film increases, and the corrosion resistance is undesirably reduced.
[0067]
A water-soluble phosphate can be added to the surface treatment composition as needed for the purpose of improving corrosion resistance. As the water-soluble phosphate, for example, one or more metal salts such as orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, and metaphosphoric acid can be used. Further, one or more kinds of salts of organic phosphoric acid (for example, phytic acid, phytate, phosphonic acid, phosphonate and metal salts thereof) may be added. Among them, the first phosphate is preferred from the viewpoint of the stability of the surface treatment composition and the like.
The form of the phosphate in the film is not particularly limited, and may be crystalline or non-crystalline. Also, there is no special restriction on the ionicity and solubility of the phosphate in the film. It is considered that the reason why the corrosion resistance is improved by blending the water-soluble phosphate is that the water-soluble phosphate forms a dense hardly soluble compound at the time of film formation.
[0068]
As mentioned earlier, the silane coupling agent chemically bonds to both the activated plating metal and the film-forming resin, thereby providing excellent adhesion and corrosion resistance between the plating metal and the film-forming resin. Inactive parts are inevitably present on the metal surface, and at such inactive sites, the above-described chemical bond is hardly generated, and the rust-preventing effect cannot be sufficiently exhibited. The water-soluble phosphate forms a dense hardly soluble compound in such a portion of the plating film when the film is formed. That is, the pH rises at the plating film / surface treatment composition interface with the dissolution of the plating film by the phosphate ions of the water-soluble phosphate, and as a result, a precipitate film of the water-soluble phosphate is formed, and this is the corrosion resistance. Contribute to the improvement of
[0069]
In addition, from the viewpoint of obtaining particularly excellent corrosion resistance, Al, Mn, Ni, and Mg are particularly desirable as the cationic species of the water-soluble phosphate, and a water-soluble phosphate containing at least one element selected from these is preferred. It is preferred to use phosphates. Examples of such a water-soluble phosphate include aluminum monophosphate, monomanganese phosphate, nickel monophosphate, and magnesium monophosphate, and among these, aluminum monophosphate is particularly preferred. Is most preferred. In addition, the cation component and P₂O₅Component molar ratio [cation] / [P₂O₅] Is preferably 0.4 to 1.0. Molar ratio [cation] / [P₂O₅] Is less than 0.4, it is not preferable because the soluble phosphoric acid impairs the insolubility of the film and lowers the corrosion resistance. On the other hand, if it exceeds 1.0, the stability of the processing solution is remarkably lost, which is not preferable.
[0070]
The compounding amount of this water-soluble phosphate is 0.1 to 60 parts by mass, preferably 0.1 part by mass, based on 100 parts by mass of the solid content of the aqueous epoxy resin dispersion liquid as the component (a). It is suitably from 5 to 40 parts by mass, more preferably from 1 to 30 parts by mass. When the amount of the water-soluble phosphate is less than 0.1 part by mass, the effect of improving the corrosion resistance is not sufficient. On the other hand, when the amount exceeds 60 parts by mass, the soluble component of the film increases, and the corrosion resistance decreases, which is not preferable. .
[0071]
The surface treatment composition may optionally contain a chromium-free rust preventive additive for the purpose of improving corrosion resistance. By blending such a non-chromium-based rust-preventive additive in the surface treatment composition, particularly excellent anticorrosion performance (self-repairing property) can be obtained.
It is particularly preferable to use one or more selected from the following (e1) to (e5) as the non-chromium rust preventive additive.
(E1) Silicon oxide
(E2) Calcium or calcium compound
(E3) Poorly soluble phosphate compound
(E4) Molybdate compound
(E5) One or more organic compounds containing an S atom selected from triazoles, thiols, thiadiazoles, thiazoles, and thiurams
Details of these (e1) to (e5) non-chromium rust preventive additives and the anticorrosion mechanism are as follows.
[0072]
First, as the component (e1), colloidal silica or dry silica, which is fine-particle silica, can be used. From the viewpoint of corrosion resistance, calcium ion-exchanged silica having calcium bonded to its surface is particularly used. Is desirable.
As the colloidal silica, for example, Snowtex O, 20, 30, 40, C, S (all trade names) manufactured by Nissan Chemical Co., Ltd. can be used. As the fumed silica, Nippon Aerosil ( AEROSIL R971, R812, R811, R974, R202, R805, 130, 200, 300, and 300CF (all trade names) manufactured by K.K. Examples of calcium ion exchange silica include W.I. R. Grace & Co. SHIELDEX C303, SHIELDEX AC3, and SHIELDEX AC5 (all trade names) manufactured by Fuji Silysia Chemical Ltd., and SHIELDEX and SHIELDEX SY710 (all trade names) can be used. These silicas contribute to the generation of dense and stable zinc corrosion products in a corrosive environment, and the corrosion products are formed densely on the plating surface, thereby suppressing the promotion of corrosion.
[0073]
Further, the components (e2) and (e3) exhibit particularly excellent anticorrosion performance (self-repairing property) due to the precipitation action.
The calcium compound as the component (e2) may be any of calcium oxide, calcium hydroxide, and calcium salt, and one or more of these can be used. In addition, there is no particular limitation on the type of calcium salt, and in addition to simple salts containing only calcium as a cation, such as calcium silicate, calcium carbonate, calcium phosphate, etc., calcium and calcium such as calcium phosphate / zinc, calcium / magnesium phosphate, etc. A double salt containing a cation other than the above may be used. In the component (e2), calcium, which is more noble than zinc or aluminum, which is a plating metal, is preferentially dissolved in a corrosive environment, and the OH generated by the cathode reaction is dissolved.⁻And block the defective part as a dense and hardly soluble product and suppress the corrosion reaction. In addition, when mixed with the above-mentioned silica, calcium ions are adsorbed on the surface and electrically neutralize the surface charge to aggregate. As a result, a dense and hardly soluble protective film is formed, the corrosion is blocked, and the corrosion reaction is suppressed.
[0074]
Further, as the sparingly soluble phosphate compound (e3), a sparingly soluble phosphate can be used. The poorly soluble phosphate includes all kinds of salts such as simple salts and double salts. Further, the metal cation constituting the metal cation is not limited, and may be any metal cation such as hardly soluble zinc phosphate, magnesium phosphate, calcium phosphate, and aluminum phosphate. The skeleton of the phosphate ion and the degree of condensation are not limited, and may be any of a normal salt, a dihydrogen salt, a monohydrogen salt, or a phosphite. Includes all condensed phosphates such as salts. This poorly soluble phosphorus compound, the zinc or aluminum of the plating metal eluted by corrosion, forms a dense and poorly soluble protective film by a complex formation reaction with phosphate ions dissociated by hydrolysis, and blocks the corrosion origin, Inhibits corrosion reactions.
[0075]
Further, as the molybdate compound (e4), for example, molybdate can be used. The molybdate is not limited in its skeleton and degree of condensation, and includes, for example, orthomolybdate, paramolybdate, metamolybdate and the like. Further, it includes all salts such as a single salt and a double salt, and examples of the double salt include molybdate phosphate. Molybdate compounds exhibit self-healing properties through a passivating effect. In other words, a dense oxide is formed on the surface of the plating film together with dissolved oxygen in a corrosive environment to block a corrosion starting point and suppress a corrosion reaction.
[0076]
Examples of the organic compound (e5) include the following. That is, as triazoles, 1,2,4-triazole, 3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5-amino-3-mercapto-1,2 , 4-triazole, 1H-benzotriazole and the like; thiols such as 1,3,5-triazine-2,4,6-trithiol and 2-mercaptobenzimidazole; and thiadiazoles such as 5- Amino-2-mercapto-1,3,4-thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole and the like, and as thiazoles, 2-N, N-diethylthiobenzothiazole, 2-mercapto Benzothiazoles and the like, and thiurams include tetraethylthiuram disulfide and the like, respectively. It is. These organic compounds exhibit self-healing properties due to the adsorption effect. That is, zinc or aluminum eluted by corrosion is adsorbed to the sulfur-containing polar group of these organic compounds to form an inert film, thereby blocking the corrosion starting point and suppressing the corrosion reaction.
[0077]
The amount of the non-chromium-based rust preventive additive is 0.1 to 50 parts by mass, preferably 0 to 50 parts by mass, based on 100 parts by mass of the solid content of the aqueous epoxy resin dispersion as the component (a). It is suitably from 0.5 to 30 parts by mass. If the amount of the non-chromium-based rust-preventive additive is less than 0.1 part by mass, the effect of improving the corrosion resistance after alkali degreasing is not sufficiently obtained, while if it exceeds 50 parts by mass, the coatability and workability are reduced. In addition to reducing the corrosion resistance.
In addition, two or more kinds of the rust-preventive additives (e1) to (e5) may be added in combination, and in this case, a unique anticorrosion action is compounded, so that higher corrosion resistance is obtained. In particular, calcium ion-exchanged silica is used as the component (e1), and one or more of the components (e3), (e4), and (e5), and particularly preferably the components (e3) to (e5), Particularly excellent corrosion resistance is obtained when all of them are added in combination.
[0078]
Further, in the surface treatment film (and the surface treatment composition), as a corrosion inhibitor, other oxide fine particles (for example, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, antimony oxide, etc.), phosphomolybdate One or two or more of such as (for example, aluminum phosphomolybdate) and an organic inhibitor (for example, hydrazine and a derivative thereof, a thiol compound, a thiocarbamate) can be added.
[0079]
Further, if necessary, organic color pigments (for example, condensed polycyclic organic pigments, phthalocyanine organic pigments, etc.) and coloring dyes (for example, water-soluble pigments) may be added to the surface treatment film (and the surface treatment composition) as additives. Azo metal dyes, etc., inorganic pigments (e.g., titanium oxide, etc.), conductive pigments (e.g., metal powders such as zinc, aluminum, nickel, iron phosphide, antimony-doped tin oxide, etc.), coupling agents (e.g., , A titanium coupling agent, etc.), melamine / cyanuric acid adduct, or two or more thereof.
The surface treatment film formed by the surface treatment composition containing the above components has a dry film thickness of 0.01 to 1.0 μm, preferably 0.1 to 0.8 μm. If the dry film thickness is less than 0.01 μm, the corrosion resistance is insufficient, while if it exceeds 1.0 μm, the conductivity and workability decrease.
[0080]
Next, a specific film structure of the surface treatment film described above will be described.
In the present invention, the film structure of the surface treatment film formed on the surface of the zinc-based steel sheet or the aluminum-based steel sheet is an amorphous compound layer containing P, Zn or / and Al and O, and a hydrazine layer thereover. Specific epoxy group-containing resin modified with a derivative, that is, a polyalkylene glycol-modified epoxy resin obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol-type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound (A), an epoxy group-containing resin (B) other than the polyalkylene glycol-modified epoxy resin (A), a hydrazine derivative (C) having active hydrogen, and, if necessary, other than the hydrazine derivative (C). Obtained by reacting with an active hydrogen-containing compound (D). An organic resin matrix layer having a water-dispersible resin as a matrix, preferably containing P, Zn or / and Al, and O in a film (amorphous compound layer and / or organic resin matrix layer) It preferably contains a precipitated compound, more preferably a precipitated compound containing P, Zn or / and Al, Si and O. This surface treatment film does not contain any chromium.
[0081]
In order to impart excellent corrosion resistance (white rust resistance) to a base-plated steel sheet such as a zinc-based steel sheet with a chromium-free film, as described above,
{Circle around (1)} An advanced barrier layer serving as a diffusion barrier for a corrosion factor is formed by an organic resin to suppress a cathode reaction.
{Circle around (2)} A dense inactive layer (reactive layer) is formed on the surface of the plating film by the reaction between the surface treatment composition and the surface layer of the plating film, and the anode reaction is suppressed by the inactivation of the surface of the plating film by the inert layer. I do.
Is effective, and more preferably,
{Circle around (3)} A self-repairing substance that reacts with and repairs a defective portion (or a damaged portion) of the above-mentioned inert layer and captures and hardens metal ions such as zinc ions to be eluted from that portion (ie, , Self-repairing).
Is effective.
[0082]
According to the surface-treated film of the surface-treated steel sheet of the present invention, a high barrier property (the effect of the above (1)) is provided by the upper organic resin matrix layer, and the lower amorphous compound layer is provided. This imparts an inactivating effect on the surface layer of the plating film (the effect of the above item (2)), and more preferably a self-repairing property (an effect of the above item (3)) by the precipitated compound contained in the film. The combined action provides the surface-treated steel sheet with high corrosion resistance.
The amorphous compound layer is a concentrated layer or film of an amorphous compound generated by the reaction between the surface treatment composition and the surface layer of the plating film, and Zn or Zn derived from the plating film components Zn and Al. / And a compound containing Al. When the galvanized steel sheet is a galvanized steel sheet, the compositional feature of the amorphous compound is that Zn and P are contained in equimolar amounts, more specifically, the molar ratio of Zn and P [Zn] / [P ] Is 0.9 to 1.4. This compound is a second phosphate compound (for example, ZnHPO₄・ 2H₂O).
[0083]
Excellent white rust resistance is obtained by the formation of such an amorphous compound layer, as described above, because this amorphous compound layer inactivates the plating layer surface layer. This is presumably because even when the corrosion factor penetrates through the upper barrier layer (organic resin matrix layer) and reaches the surface of the plating film, the anode reaction relating to the generation of white rust is suppressed.
The thickness of the amorphous compound layer is preferably 10 nm or more from the viewpoint of corrosion resistance.
In order to positively form the amorphous compound layer, it is preferable that the heat treatment after applying the surface treatment composition is performed by an induction heating method (induction heating furnace). This is because, in the heating by the induction heating method, since the heating is performed from the steel sheet side, the reaction between the plating film and the surface treatment composition is promoted, which is a favorable condition for forming the amorphous compound layer.
[0084]
The surface treatment film usually contains a silane compound derived from a silane coupling agent contained in the surface treatment composition. In addition, this silane compound includes the case where it is contained in a composition as a silane coupling agent.
Further, in order to impart high white rust resistance to the surface treatment film, the surface treatment film preferably contains a specific precipitation compound. This precipitated compound is an amorphous precipitated compound containing P, Zn or / and Al and O, and when the precipitated compound contains Si, the effect of improving white rust resistance is further enhanced. Zn and Al contained in the deposited compound are derived from Zn and Al which are plating film components, and Si is derived from a silane coupling agent contained in the surface treatment composition.
[0085]
The deposited compound is considered to be a reaction product (compound) of the plating metal dissolved from the plating film and mainly the acid component in the surface treatment composition, and an appropriate amount of acid component (such as phosphoric acid) in the surface treatment composition. ) Can be generated (precipitated) in the film. In addition, among the precipitates, the precipitated compound containing Si is a compound obtained by incorporating the silane coupling agent component in the surface treatment composition into the compound, and such a precipitated compound is also contained in the surface treatment composition. By optimizing the addition amount of the silane coupling agent (making the addition amount relatively large), it can be formed (precipitated) in the film.
[0086]
It is not always clear why the above-mentioned precipitated compound is contained in the surface treatment film to improve white rust resistance, but acid components such as phosphate ions eluted from the precipitated compound are eluted from the plating film during the corrosion process. It is presumed that the insoluble compound is formed by binding to the metal ion such as zinc ion and the like, and a stable precipitation protective film is formed to suppress corrosion (exhibit self-repairing property).
Further, it is not always clear why better white rust resistance is obtained by including Si in the precipitated compound, but the inclusion of Si enhances the solubility of the precipitated compound in a corrosive environment, Factors such as the incorporation of Si in the amorphous compound layer into the amorphous compound layer to make the reaction product with metal ions such as zinc ions eluted from the plating film in the corrosion process more stable are considered.
When the galvanized steel sheet is a galvanized steel sheet, the precipitation compound contained in the surface treatment film usually contains Zn and P in equimolar amounts. More specifically, the molar ratio [Zn] / [P] of Zn and P is 0.9 to 1.4, and this compound is a second phosphate compound (for example, ZnHPO₄・ 2H₂O).
[0087]
On the other hand, when a precipitation compound having a molar ratio [Zn] / [P] of Zn and P of less than 1.0 was precipitated in the surface treatment film, a precipitation compound containing equimolar amounts of Zn and P was deposited. The white rust resistance is further improved as compared with the case. The precipitated compound having a molar ratio [Zn] / [P] of less than 1.0 is a water-soluble primary phosphate (for example, Zn (H₂PO₄)₂・ H₂O) It is presumed to be the main compound. The reason why particularly excellent white rust resistance can be obtained by precipitating such a compound is not necessarily clear, but the precipitated compound is a metal such as zinc ion that is liable to elute from a defective portion of the amorphous compound layer. It is presumed that by reacting with ions to form a hardly soluble diphosphate (for example, zinc diphosphate), a high degree of function as a self-repairing substance is achieved.
[0088]
As described above, the thickness of the surface treatment film described above is 0.01 to 2.0 μm, preferably 0.1 to 1.5 μm. Further, the surface treatment film may contain a chromium-free rust preventive additive, a solid lubricant, and the like as described above.
In addition, the surface treatment composition for forming the surface treatment film needs to be of an aqueous solvent type to generate the compound layer (amorphous compound layer) and the precipitated compound as described above, and therefore, it is necessary to use an organic solvent. A water-dispersible resin is used as the resin.
[0089]
Next, the details of the method for measuring the film composition of the above-mentioned surface treatment film will be described. Quantitative values of the local composition of the film cross section obtained by the currently widely used transmission electron microscope and energy dispersive X-ray analyzer are based on the method of preparing the cross section sample, data measurement conditions, data processing method, and quantitative correction calculation. The reality is that it changes depending on the law. This is because (1) it is practically impossible to sequentially prepare a standard sample for elemental analysis suitable for an unknown sample that can be observed with a transmission electron microscope. Therefore, quantitative calculation based on theoretical calculation without using a standard sample is required. There is no choice but to use various calculation models. (2) The quantitative calculation method of the relative concentration of heavy elements over Na to light elements below Na is not established worldwide. It is due to. In addition to such a situation, how to handle characteristic X-rays from a portion other than the measurement target portion due to the shape of the cross-sectional sample, the support for the cross-sectional sample, and the like greatly affects the quantitative result.
[0090]
Therefore, in the present invention, the following method was used for measuring the film composition. First, a cross-section sample for a transmission electron microscope was prepared using a microsampling mechanism attached to a FB2000A focused ion beam processing apparatus (Focused Ion Beam: FIB) manufactured by Hitachi, Ltd. Prior to the FIB processing, a protective film of C was flash-evaporated to about 200 nm on the surface of the sample piece of the surface-treated steel sheet for preparing the cross-sectional sample to protect it from damage caused by ion beam irradiation. Further, an Au protective film was sputter-coated at about 100 nm. Using a chemical vapor deposition (CVD) mechanism of the FIB processing apparatus, a C protective film was further coated around 500 nm on the surface of the cut-out section of the test material introduced into the FIB processing apparatus. Processing was performed. The cross-sectional sample taken out using the micro-sampling mechanism was fixed to a linear portion of a Mo-shaped meniscus-shaped special mesh using a CVD mechanism, and then finished to a film thickness suitable for transmission electron microscope observation.
For the composition analysis of the cross-sectional sample thus prepared, a transmission electron microscope CM20FEG manufactured by Philips equipped with a field emission electron gun and an energy meter manufactured by EDAX equipped with a Super-UTW type detector attached thereto were used. A dispersive X-ray analyzer, Phoenix, was used. The accelerating voltage at the time of microscopic image observation and elemental analysis was 200 kV.
[0091]
The compositions of the amorphous compound layer and the precipitated compound were determined by performing background removal, peak separation, and quantitative correction calculations from the spectral data collected from these positions. At this time, if the background processing is performed automatically, the net intensity (net intensity) in the light element region may not be calculated properly. Therefore, manually specifying the energy position where no peak appears and connecting it to the manual position Treated (removed) in the ground system. In the peak separation, characteristic meshes such as Mo and Au caused by the Mo protective layer used as a support for the cross-sectional sample, and the Au protective layer, and Ga caused by the FIB processing were also considered. All the quantitative calculations were performed using K-series characteristic X-rays of each element contained in the chemical conversion treatment film. The correction calculation is performed by thin film approximation, and the correction factor (so-called K_ABThe factor) was a Zaluzec model.
The molar ratio between Zn and P of the amorphous compound layer and the precipitated compound of the surface treatment film can be obtained as the ratio of the atomic concentration of Zn and P thus obtained.
[0092]
Next, an upper layer film (organic film) formed as a second layer film on the surface treatment film will be described.
The upper layer film is formed by a reaction between a film forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. It is a film having a thickness of 0.5 to 2.0 μm. This upper coating also contains no chromium.
[0093]
As the type of the film-forming organic resin (E), some or all of the compounds react with an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) having active hydrogen, and the film-forming organic resin contains active hydrogen. There are no particular restrictions on the resin as long as the compound (F) can be bonded by a reaction such as addition or condensation and a film can be appropriately formed. Examples of the film-forming organic resin (E) include an epoxy resin, a modified epoxy resin, a polyurethane resin, a polyester resin, an alkyd resin, an acrylic copolymer resin, a polybutadiene resin, a phenol resin, and an adduct of these resins or Condensates and the like can be mentioned, and one of these can be used alone or as a mixture of two or more.
[0094]
As the film-forming organic resin (E), an epoxy group-containing resin (H) having an epoxy group in the resin is particularly preferable from the viewpoints of reactivity, easiness of reaction, anticorrosion property and the like. As the epoxy group-containing resin (H), some or all of the compounds react with an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) having an active hydrogen to give the film-forming organic resin an active hydrogen-containing compound. There is no particular limitation as long as (F) is a resin that can be bonded by a reaction such as addition or condensation and that can appropriately form a film. For example, an epoxy resin, a modified epoxy resin, an acrylic copolymer copolymerized with an epoxy group-containing monomer Examples thereof include copolymer resins, polybutadiene resins having an epoxy group, polyurethane resins having an epoxy group, and adducts or condensates of these resins. One of these epoxy group-containing resins may be used alone or in combination of two or more. They can be used in combination.
Among these epoxy group-containing resins (H), an epoxy resin and a modified epoxy resin are particularly preferable from the viewpoint of adhesion to a plating surface and corrosion resistance. Among them, thermosetting epoxy resin and modified epoxy resin, which have excellent barrier properties against corrosion factors such as oxygen, are most suitable, and especially the amount of coating film to obtain high conductivity and spot weldability. It is particularly advantageous when is low.
[0095]
As the epoxy resin, a glycidyl group is introduced by reacting a polyphenol such as bisphenol A, bisphenol F, and novolak phenol with an epihalohydrin such as epichlorohydrin, or the glycidyl group-introduced reaction product further comprises polyphenols. Aromatic epoxy resin obtained by increasing the molecular weight by reacting the above, furthermore, aliphatic epoxy resin, alicyclic epoxy resin, and the like. One of these may be used alone, or two or more may be used in combination. Can be. It is preferable that these epoxy resins have a number average molecular weight of 1500 or more especially when a film-forming property at a low temperature is required.
[0096]
Examples of the modified epoxy resin include a resin obtained by reacting various modifiers with an epoxy group or a hydroxyl group in the epoxy resin, such as an epoxy ester resin obtained by reacting a drying oil fatty acid, acrylic acid or methacrylic acid. Examples thereof include an epoxy acrylate resin modified with a polymerizable unsaturated monomer component containing, and a urethane modified epoxy resin reacted with an isocyanate compound.
[0097]
As the acrylic copolymer resin copolymerized with the epoxy group-containing monomer, an unsaturated monomer having an epoxy group and a polymerizable unsaturated monomer component essentially including an acrylate or a methacrylate, a solution polymerization method, Resins synthesized by an emulsion polymerization method or a suspension polymerization method can be used.
Examples of the polymerizable unsaturated monomer component include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-, iso- or tert-butyl (meth) acrylate, hexyl (meth) acrylate, C1-24 alkyl esters of acrylic acid or methacrylic acid such as 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate; acrylic acid, methacrylic acid, styrene, vinyltoluene, acrylamide, acrylonitrile, N- Examples include methylol (meth) acrylamide, a C1-4 alkyl etherified product of N-methylol (meth) acrylamide, and N, N-diethylaminoethyl methacrylate.
[0098]
The unsaturated monomer having an epoxy group is not particularly limited as long as it has an epoxy group and a polymerizable unsaturated group such as glycidyl methacrylate, glycidyl acrylate, and 3,4-epoxycyclohexylmethyl (meth) acrylate. .
In addition, the acrylic copolymer resin copolymerized with the epoxy group-containing monomer may be a resin modified with a polyester resin, an epoxy resin, a phenol resin, or the like.
[0099]
Particularly preferred as the epoxy resin is a resin having a chemical structure represented by the following formula, which is a reaction product of bisphenol A and epihalohydrin. This epoxy resin is particularly preferred because of its excellent corrosion resistance.
Embedded image

Methods for producing such bisphenol A type epoxy resins are widely known in the art. In the above chemical structural formula, q is 0 to 50, preferably 1 to 40, and particularly preferably 2 to 20.
In addition, the film-forming organic resin (E) may be any of an organic solvent dissolving type, an organic solvent dispersing type, a water dissolving type, and a water dispersing type.
[0100]
The present invention aims at providing a hydrazine derivative in the molecule of the film-forming organic resin (E). Therefore, at least a part (preferably, all) of the active hydrogen-containing compound (F) contains hydrazine having active hydrogen. It must be a derivative (G).
When the film-forming organic resin (E) is an epoxy group-containing resin, examples of the active hydrogen-containing compound (F) that reacts with the epoxy group include the following, and one or more of these may be used. Although it can be used, also in this case, it is necessary that at least a part (preferably all) of the active hydrogen-containing compound (F) is a hydrazine derivative having active hydrogen.
.Hydrazine derivatives having active hydrogen
.Primary or secondary amine compounds having active hydrogen
・ Organic acids such as ammonia and carboxylic acid
・ Hydrogen halide such as hydrogen chloride
・ Alcohols, thiols
A quaternary chlorinating agent which is a mixture of a hydrazine derivative having no active hydrogen or a tertiary amine and an acid
[0101]
Examples of the hydrazine derivative (G) having an active hydrogen include the following.
(1) Carbohydrazide, propionic hydrazide, salicylic hydrazide, adipic dihydrazide, sebacic dihydrazide, dodecanoic dihydrazide, isophthalic dihydrazide, thiocarbohydrazide, 4,4'-oxybisbenzenesulfonyl hydrazide, benzophenone polyhydramide, benzophenone polyhydramide Hydrazide compounds such as;
(2) pyrazole compounds such as pyrazole, 3,5-dimethylpyrazole, 3-methyl-5-pyrazolone and 3-amino-5-methylpyrazole;
[0102]
(3) 1,2,4-triazole, 3-amino-1,2,4-triazole, 4-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 5-amino -3-mercapto-1,2,4-triazole, 2,3-dihydro-3-oxo-1,2,4-triazole, 1H-benzotriazole, 1-hydroxybenzotriazole (monohydrate), 6- Triazole compounds such as methyl-8-hydroxytriazolopyridazine, 6-phenyl-8-hydroxytriazolopyridazine, 5-hydroxy-7-methyl-1,3,8-triazaindolizine;
[0103]
(4) tetrazole compounds such as 5-phenyl-1,2,3,4-tetrazole and 5-mercapto-1-phenyl-1,2,3,4-tetrazole;
(5) thiadiazole compounds such as 5-amino-2-mercapto-1,3,4-thiadiazole and 2,5-dimercapto-1,3,4-thiadiazole;
{Circle around (6)} Maleic hydrazide, 6-methyl-3-pyridazone, 4,5-dichloro-3-pyridazone, 4,5-dibromo-3-pyridazone, 6-methyl-4,5-dihydro-3-pyridazone and the like Pyridazine compounds
[0104]
Of these, pyrazole compounds and triazole compounds having a 5- or 6-membered ring structure and having a nitrogen atom in the ring structure are particularly preferred. These hydrazine derivatives can be used alone or in combination of two or more.
[0105]
Representative examples of the amine compound having active hydrogen that can be used as a part of the active hydrogen-containing compound (F) include, for example, the following compounds.
{Circle around (1)} A primary amino group of an amine compound having one secondary amino group and one or more primary amino groups such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, and methylaminopropylamine is converted to a ketone, A compound modified with aldemine, ketimine, oxazoline or imidazoline by heat reaction with aldehyde or carboxylic acid at a temperature of, for example, about 100 to 230 ° C;
[0106]
(2) Secondary monoamines such as diethylamine, diethanolamine, di-n- or -iso-propanolamine, N-methylethanolamine, N-ethylethanolamine;
(3) a secondary amine-containing compound obtained by adding a monoalkanolamine such as monoethanolamine and a dialkyl (meth) acrylamide by a Michael addition reaction;
{Circle around (4)} Compounds in which the primary amino group of an alkanolamine such as monoethanolamine, neopentanolamine, 2-aminopropanol, 3-aminopropanol, 2-hydroxy-2 ′ (aminopropoxy) ethyl ether is modified to ketimine;
[0107]
The quaternary chlorinating agents that can be used as a part of the active hydrogen-containing compound (F) include hydrazine derivatives having no active hydrogen or tertiary amines, which themselves have no reactivity with epoxy groups. It is a mixture with an acid so that it can react with the acid. The quaternary chlorinating agent reacts with an epoxy group in the presence of water, if necessary, to form a quaternary salt with the epoxy group-containing resin.
The acid used to obtain the quaternary chlorinating agent may be any of organic acids such as acetic acid and lactic acid and inorganic acids such as hydrochloric acid. Further, as a hydrazine derivative having no active hydrogen used for obtaining a quaternary chlorinating agent, for example, 3,6-dichloropyridazine and the like, and as a tertiary amine, for example, dimethylethanolamine, triethylamine, Trimethylamine, triisopropylamine, methyldiethanolamine and the like can be mentioned.
[0108]
The reaction product of the film-forming organic resin (E) and an active hydrogen-containing compound (F) comprising a hydrazine derivative (G) in which some or all of the compounds have active hydrogen is formed of the film-forming organic resin (E) and active hydrogen It is obtained by reacting the compound (F) with the compound (F) at 10 to 300 ° C, preferably 50 to 150 ° C for about 1 to 8 hours.
This reaction may be performed by adding an organic solvent, and the type of the organic solvent used is not particularly limited. For example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, dibutyl ketone and cyclohexanone; ethanol, butanol, 2-ethylhexyl alcohol, benzyl alcohol, ethylene glycol, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether Hydroxyl-containing alcohols and ethers such as propylene glycol, propylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether; esters such as ethyl acetate, butyl acetate, and ethylene glycol monobutyl ether acetate; toluene, xylene Such as aromatic hydrocarbons Illustration can, it is possible to use one or more of these. Among these, ketone-based or ether-based solvents are particularly preferable from the viewpoints of solubility with an epoxy resin, coatability, and the like.
[0109]
The compounding ratio of the film-forming organic resin (E) and the active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen is determined by the ratio of solid content to the film-forming organic resin (E). The amount of the active hydrogen-containing compound (F) is preferably 0.5 to 20 parts by mass, particularly preferably 1.0 to 10 parts by mass, per 100 parts by mass.
When the film-forming organic resin (E) is an epoxy group-containing resin (H), the mixing ratio of the epoxy group-containing resin (H) and the active hydrogen-containing compound (F) is determined by the following formula. ) The number of active hydrogen groups and the number of epoxy groups of the epoxy group-containing resin (H) [the number of active hydrogen groups / the number of epoxy groups] is 0.01 to 10, more preferably 0.1 to 8, and still more preferably. 0.2 to 4 is appropriate from the viewpoint of corrosion resistance and the like.
[0110]
The proportion of the hydrazine derivative (G) having active hydrogen in the active hydrogen-containing compound (F) is preferably 10 to 100 mol%, more preferably 30 to 100 mol%, and further preferably 40 to 100 mol%. Appropriate. If the ratio of the hydrazine derivative (G) having active hydrogen is less than 10 mol%, a sufficient rust-preventing function cannot be imparted to the organic film, and the obtained rust-preventive effect is obtained by simply mixing the hydrazine derivative with the film-forming organic resin. There is no big difference from the case of using.
[0111]
In the present invention, in order to form a dense barrier film, it is desirable to mix a curing agent into the resin composition and heat-cur the organic film (upper layer film).
As the curing method for forming the resin composition film, (1) a curing method utilizing a urethanization reaction between an isocyanate and a hydroxyl group in the base resin, and (2) a curing method selected from melamine, urea and benzoguanamine. An etherification reaction between an alkyl etherified amino resin obtained by reacting a monohydric alcohol having 1 to 5 carbon atoms with a part or all of a methylol compound obtained by reacting formaldehyde with at least one species and a hydroxyl group in a base resin is carried out. The curing method to be used is suitable, and among these, it is particularly preferred that the main reaction is a urethanization reaction between the isocyanate and the hydroxyl group in the base resin.
[0112]
The polyisocyanate compound used in the curing method (1) is an aliphatic, alicyclic (including heterocyclic) or aromatic isocyanate compound having at least two isocyanate groups in one molecule, or a mixture of these compounds. A compound partially reacted with a dihydric alcohol. Examples of such a polyisocyanate compound include the following.
(1) m- or p-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate, o- or p-xylylene diisocyanate, hexamethylene diisocyanate, dimer acid diisocyanate, isophorone diisocyanate
[0113]
{Circle around (2)} The compound of the above [1] alone or a mixture thereof and a polyhydric alcohol (a dihydric alcohol such as ethylene glycol and propylene glycol; a trihydric alcohol such as glycerin and trimethylolpropane; a tetrahydric alcohol such as pentaerythritol; A reaction product with at least two isocyanates in one molecule such as sorbitol and dihydric alcohol such as dipentaerythritol.
These polyisocyanate compounds can be used alone or in combination of two or more.
[0114]
Further, as a protective agent (blocking agent) for the polyisocyanate compound, for example,
(1) Aliphatic monoalcohols such as methanol, ethanol, propanol, butanol and octyl alcohol
{Circle around (2)} Monoethers of ethylene glycol and / or diethylene glycol, for example, monoethers such as methyl, ethyl, propyl (n-, iso) and butyl (n-, iso, sec)
(3) Aromatic alcohols such as phenol and cresol
(4) Oxime such as acetoxime and methyl ethyl ketone oxime
By reacting one or more of these with the polyisocyanate compound, a polyisocyanate compound that is stably protected at least at room temperature can be obtained.
[0115]
Such a polyisocyanate compound (I) is (E) / (I) = 95/5 to 55/45 (weight ratio of non-volatile components), preferably ( It is appropriate to mix at a ratio of E) / (I) = 90/10 to 65/35. The polyisocyanate compound has water absorbency, and if it is added in a proportion exceeding (E) / (I) = 55/45, the adhesion of the upper layer film is deteriorated. Furthermore, when an overcoat is applied on the upper layer film, the unreacted polyisocyanate compound moves into the coating film, causing curing inhibition and poor adhesion of the coating film. From such a viewpoint, the blending amount of the polyisocyanate compound (I) is preferably (E) / (I) = 55/45 or less.
[0116]
The film-forming organic resin (E) is sufficiently cross-linked by the addition of the above-mentioned cross-linking agent (curing agent). However, in order to further increase the low-temperature cross-linking property, it is desirable to use a known curing promoting catalyst. As the curing promoting catalyst, for example, N-ethylmorpholine, dibutyltin dilaurate, cobalt naphthenate, stannous chloride, zinc naphthenate, bismuth nitrate and the like can be used.
For example, when an epoxy group-containing resin is used for the film-forming organic resin (E), a known resin such as acryl, alkyd, or polyester is mixed with the epoxy group-containing resin in order to slightly improve physical properties such as adhesion. It can also be used.
[0117]
The upper layer coating may contain a chromium-free rust-preventive additive as needed for the purpose of improving corrosion resistance. By including such a non-chromium-based rust-preventive additive in the upper film, more excellent anticorrosion performance can be obtained.
It is particularly preferable to use one or more selected from the following (e1) to (e5) as the non-chromium rust preventive additive.
(E1) Silicon oxide
(E2) Calcium or calcium compound
(E3) Poorly soluble phosphate compound
(E4) Molybdate compound
(E5) One or more organic compounds containing an S atom selected from triazoles, thiols, thiadiazoles, thiazoles, and thiurams
The details of the non-chromium-based rust-preventive additives (e1) to (e5) and the anti-corrosion mechanism are as described above for the surface treatment film.
[0118]
The amount of the non-chrome-based rust-preventive additive is 0.1 to 50 parts by mass, preferably 0.5 to 30 parts by mass, based on 100 parts by mass of the solid content of the resin composition for forming a film. Is appropriate. If the amount of the non-chromium-based rust-preventive additive is less than 0.1 part by mass, the effect of improving corrosion resistance after alkali degreasing is not sufficiently obtained. This is not preferred because not only the corrosion resistance is lowered but also the corrosion resistance is lowered.
In addition, two or more kinds of the rust-preventive additives (e1) to (e5) may be added in combination, and in this case, a unique anticorrosion action is compounded, so that higher corrosion resistance is obtained. In particular, calcium ion-exchanged silica is used as the component (e1), and one or more of the components (e3), (e4), and (e5), and particularly preferably the components (e3) to (e5), Particularly excellent corrosion resistance is obtained when all of them are added in combination.
[0119]
In addition, in addition to the above-mentioned rust-preventive additive component, other oxide fine particles (for example, aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, antimony oxide, etc.), phosphomolybdic acid are contained in the upper layer film in addition to the corrosion inhibitor. Salts (eg, aluminum phosphomolybdate, etc.), organophosphoric acids and salts thereof (eg, phytic acid, phytate, phosphonic acid, phosphonate, and their metal salts, alkali metal salts, alkaline earth metal salts, etc.) ), Organic inhibitors (eg, hydrazine derivatives, thiol compounds, dithiocarbamates, etc.).
[0120]
If necessary, a solid lubricant can be added to the upper layer coating for the purpose of improving the processability of the coating.
Examples of the solid lubricant applicable to the present invention include the following, and one or more of these can be used. .
(1) Polyolefin wax, paraffin wax: for example, polyethylene wax, synthetic paraffin, natural paraffin, micro wax, chlorinated hydrocarbon, etc.
(2) Fluororesin fine particles: for example, polyfluoroethylene resin (polytetrafluoroethylene resin or the like), polyvinyl fluoride resin, polyvinylidene fluoride resin, etc.
[0121]
Other than these, fatty acid amide compounds (eg, stearic acid amide, palmitic acid amide, methylene bisstearamide, ethylenebisstearamide, oleic acid amide, esylic acid amide, alkylenebisfatty acid amide, etc.), metals Soaps (eg, calcium stearate, lead stearate, calcium laurate, calcium palmitate, etc.), metal sulfides (eg, molybdenum disulfide, tungsten disulfide, etc.), graphite, graphite fluoride, boron nitride, polyalkylene glycol, One or more kinds of alkali metal sulfates may be used.
[0122]
Among the above solid lubricants, polyethylene wax and fine particles of fluororesin (particularly, fine particles of polytetrafluoroethylene resin) are particularly preferable.
Examples of the polyethylene wax include, for example, Celidust 9615A, Celidust 3715, Celidust 3620, and Celidust 3910 (trade names) manufactured by Hoechst, and Sunwax 131-P and Sunwax 161-P (manufactured by Sanyo Chemical Industries, Ltd.). Trade name), Chemipearl W-100, Chemipearl W-200, Chemipearl W-500, Chemipearl W-800, Chemipearl W-950 (all trade names) manufactured by Mitsui Petrochemical Co., Ltd. can be used.
[0123]
As the fluororesin fine particles, tetrafluoroethylene fine particles are most preferable. For example, Lubron L-2 and Lubron L-5 (all trade names) manufactured by Daikin Industries, Ltd., and MP1100 manufactured by DuPont Mitsui Co., Ltd. , MP1200 (all trade names), Fullon Dispersion AD1, Fullon Dispersion AD2, Fullon L141J, Fullon L150J, Fullon L155J (all trade names) manufactured by Asahi ICI Fluoropolymers Co., Ltd. are suitable.
Among them, a particularly excellent lubricating effect can be expected by using a combination of polyolefin wax and fine particles of tetrafluoroethylene.
[0124]
The compounding amount of the solid lubricant in the upper layer coating is 1 to 30 parts by mass (solids), preferably 1 to 10 parts by mass (solids) with respect to 100 parts by mass (solids) of the resin composition for film formation. Minutes). If the compounding amount of the solid lubricant is less than 1 part by mass, the lubricating effect is poor. On the other hand, if the compounding amount exceeds 30 parts by mass, the coatability is undesirably reduced.
[0125]
The upper layer film of the surface-treated steel sheet of the present invention is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. (Resin composition) as a main component, and if necessary, a curing agent, a chromium-free rust-preventive additive, a solid lubricant, etc. are added, and if necessary, an organic coloring pigment is further added as an additive. (Eg, condensed polycyclic organic pigments, phthalocyanine-based organic pigments, etc.), coloring dyes (eg, organic solvent-soluble azo-based dyes, water-soluble azo-based metal dyes, etc.), inorganic pigments (eg, titanium oxide, etc.), chelating agents (Eg, thiol), conductive pigments (eg, metal powders such as zinc, aluminum, nickel, etc., iron phosphide, antimony-doped tin oxide, etc.), and coupling agents (eg, silane) Coupling agent, titanium coupling agent) may be added to one or more of melamine-cyanuric acid adduct.
[0126]
The coating composition for forming a film containing the main component and the additional component usually contains a solvent (organic solvent and / or water), and further contains a neutralizer and the like as necessary.
The organic solvent is not particularly limited as long as it can dissolve or disperse a reaction product of the film-forming organic resin (E) and the active hydrogen-containing compound (F) and can adjust the reaction product as a coating composition. Various organic solvents exemplified above can be used.
The neutralizing agent is added as necessary to neutralize the film-forming organic resin (E) to make it aqueous, and when the film-forming organic resin (E) is a cationic resin, Acids such as acetic acid, lactic acid and formic acid can be used as neutralizing agents.
The dry film thickness of the upper layer film is 0.5 to 2.0 μm, preferably 0.5 to 1.5 μm. If the film thickness of the upper layer film is less than 0.5 μm, the corrosion resistance is insufficient, while if the film thickness exceeds 2.0 μm, the weldability and the electrodeposition coating property deteriorate.
In addition, from the viewpoint of weldability and electrodeposition coating properties, the total thickness of the surface treatment film of the first layer and the upper film of the second layer is preferably 2.0 μm or less.
[0127]
Next, a method for producing the surface-treated steel sheet of the present invention will be described.
In order to form the surface treatment film on the surface of a zinc-based steel sheet or an aluminum-based steel sheet, a surface treatment composition (treatment liquid) having the above-described composition is applied to the surface of the steel sheet so that the dry film thickness is within the above range. Apply and heat dry without washing.
[0128]
The method for forming the surface treatment composition on the surface of the plated steel sheet may be any of a coating method, an immersion method, and a spray method. As a coating treatment method, any method such as a roll coater (three-roll method, two-roll method, etc.), a squeeze coater, a die coater and the like may be used. Further, after the coating or dipping treatment with a squeeze coater or the like, and the spraying treatment, it is also possible to adjust the coating amount, uniform the appearance, and uniform the film thickness by an air knife method or a roll drawing method.
[0129]
After coating the surface treatment composition, heat drying is performed without washing with water. As the heating and drying means, a dryer, a hot air oven, a high-frequency induction heating oven, an infrared oven, or the like can be used. The heating and drying is desirably performed at a temperature of the ultimate plate temperature of 30 to 150 ° C, preferably 40 to 140 ° C. If the heating and drying temperature is lower than 30 ° C., a large amount of water remains in the film, and the corrosion resistance becomes insufficient. On the other hand, when the heating and drying temperature exceeds 150 ° C., not only is it uneconomical, but also the coating becomes defective and the corrosion resistance is reduced. On the other hand, if the heating and drying temperature exceeds 150 ° C., it cannot be applied to a BH steel sheet, which is not preferable.
On the upper layer of the surface treatment film formed as described above, an upper layer film (organic resin film) is formed as a second layer film. The coating composition for the second layer film is applied to the surface-treated film surface so as to have the above-mentioned film thickness, and is dried by heating. The application of the coating composition may be performed according to the method used for forming the above-mentioned surface treatment film.
[0130]
After application of the coating composition, heating and drying are usually performed without washing with water, but a washing step may be performed after application of the coating composition. For the heating and drying treatment, a dryer, a hot-blast furnace, a high-frequency induction heating furnace, an infrared furnace, or the like can be used. The heating and drying is desirably performed at a temperature of the ultimate plate temperature of 30 to 150 ° C, preferably 40 to 140 ° C. If the heating and drying temperature is lower than 30 ° C., a large amount of water remains in the film, and the corrosion resistance becomes insufficient. On the other hand, when the heating and drying temperature exceeds 150 ° C., not only is it uneconomical, but also the coating becomes defective and the corrosion resistance is reduced. On the other hand, if the heating and drying temperature exceeds 150 ° C., it cannot be applied to a BH steel sheet, which is not preferable.
[0131]
Therefore, the method for producing a surface-treated steel sheet of the present invention and preferred embodiments thereof are as follows.
[1] Applying a surface treatment composition containing the following components (a) to (c) to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and drying at a temperature of the reached sheet temperature of 30 to 150 ° C. To form a surface treatment film having a film thickness of 0.01 to 1.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol-type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water.
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
(C) phosphoric acid and / or hexafluorometallic acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
In the upper layer, the main component of the resin composition is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A high corrosion resistant surface-treated steel sheet, wherein an upper layer film having a film thickness of 0.5 to 2.0 μm is formed by applying a coating composition comprising Manufacturing method.
[0132]
[2] Applying a surface treatment composition containing the following components (a) to (c) to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and drying the sheet at a temperature of 30 to 150 ° C. To form a surface treatment film having a film thickness of 0.01 to 1.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol-type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified Obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A), a hydrazine derivative (C) having an active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C). Aqueous epoxy resin dispersion obtained by dispersing resin in water
(B) Silane coupling agent: 1 to 300 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
(C) phosphoric acid and / or hexafluorometallic acid: 0.1 to 80 parts by mass with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion.
In the upper layer, the main component of the resin composition is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A high corrosion resistant surface-treated steel sheet, wherein an upper layer film having a film thickness of 0.5 to 2.0 μm is formed by applying a coating composition comprising Manufacturing method.
[0133]
[3] In the production method according to the above [1] or [2], the epoxy group-containing resin (B) for obtaining the aqueous epoxy resin dispersion of the component (a) is a bisphenol A type epoxy resin having an epoxy equivalent of 150 to 5,000. Wherein the number-average molecular weight is from 1500 to 10000.
[4] The method according to any one of [1] to [3] above, wherein the aqueous epoxy resin dispersion of the component (a) further contains a curing agent having a group capable of crosslinking with a hydroxyl group. Manufacturing method of corrosion resistant surface treated steel sheet.
[5] In the production method according to any one of the above [1] to [4], the surface treatment composition for forming a surface treatment film further comprises a water-soluble phosphate and an aqueous epoxy resin dispersion of the component (a). A method for producing a highly corrosion-resistant surface-treated steel sheet, comprising 0.1 to 60 parts by mass of a solid content based on 100 parts by mass of a solid content.
[0134]
[6] In the production method according to the above [5], the surface treatment composition for forming a surface treatment film comprises a water-soluble phosphate, a cation component and a P component.₂O₅Component molar ratio [cation] / [P₂O₅] Is 0.4 to 1.0, and the cationic species is at least one selected from Mn, Mg, Al and Ni. Manufacturing method of treated steel sheet.
[7] In the production method according to any one of the above [1] to [6], the surface treatment composition for forming a surface treatment film further contains a non-chromium-based rust-preventive additive in which the component (a) is dispersed in an aqueous epoxy resin. A method for producing a highly corrosion-resistant surface-treated steel sheet, comprising 0.1 to 50 parts by mass of a solid content based on 100 parts by mass of a solid content of a liquid.
[8] In the production method according to any one of the above [1] to [7], the coating composition for forming an upper layer film further comprises a non-chromium-based rust-preventive additive based on 100 parts by mass of a solid content of the resin composition. A method for producing a highly corrosion-resistant surface-treated steel sheet, comprising 0.1 to 50 parts by mass in terms of solid content.
[0135]
[9] In the production method according to the above [7] or [8], the surface treatment composition for forming a surface treatment film and / or the coating composition for forming an upper layer film comprises the following non-chromium-based rust-preventive additive: A method for producing a highly corrosion-resistant surface-treated steel sheet, comprising one or more rust preventive additives selected from e1) to (e5).
(E1) Silicon oxide
(E2) Calcium and / or calcium compound
(E3) Poorly soluble phosphate compound
(E4) Molybdate compound
(E5) One or more organic compounds containing an S atom selected from triazoles, thiols, thiadiazoles, thiazoles, and thiurams
[10] The method according to any one of the above [1] to [9], wherein the silane coupling agent of the component (b) contains at least one silane coupling agent having an amino group as a reactive functional group. A method for producing a highly corrosion-resistant surface-treated steel sheet, characterized in that:
[11] In the production method according to any one of the above [1] to [10], the coating composition for forming an upper layer film further comprises a solid lubricant and a solid content based on 100 parts by mass of a solid content of the resin composition. A method for producing a highly corrosion-resistant surface-treated steel sheet, comprising 1 to 30 parts by mass in proportion.
[0136]
In addition, the above-mentioned surface treatment film and upper layer film may be formed on either one side or both sides of the plated steel sheet. The combination of the film forms on the front and back surfaces of the plated steel sheet includes, for example, surface treatment film + upper layer film / untreated, An arbitrary form such as a surface treatment film + upper layer film / surface treatment film or a surface treatment film + upper layer film / surface treatment film + upper layer film can be used.
[0137]
【Example】
[Example 1]
As the surface treatment composition for forming the first layer, a water-soluble or water-dispersible epoxy resin shown in Table 2 was used as a resin composition, and a silane coupling agent (Table 3), phosphoric acid or hexafluorometallic acid ( Table 4) A water-soluble phosphate (Table 5) and a chromium-free rust preventive additive (Table 6) are appropriately blended, and the mixture is stirred for a predetermined time using a paint dispersing machine (sand grinder) to obtain a surface treatment composition. Was prepared.
The water-soluble or water-dispersible epoxy resins shown in Table 2 were produced as follows.
・ Manufacture of polyalkylene glycol-modified epoxy resin
<Production Example 1>
To a glass four-necked flask equipped with a thermometer, a stirrer, and a condenser, 1688 g of polyethylene glycol having a number average molecular weight of 4000 and 539 g of methyl ethyl ketone were added, and the mixture was stirred and mixed at 60 ° C. to be uniformly transparent. Then, 171 g of tolylene diisocyanate was added. After adding and reacting for 2 hours, 1121 g of Epicoat 834X90 (epoxy resin, manufactured by Shell Japan Co., Ltd., epoxy equivalent 250), 66 g of diethyleneglycol ethyl ether and 1.1 g of 1% dibutyltin dilaurate solution were added, and further reacted for 2 hours. I let it. Thereafter, the temperature was raised to 80 ° C., and the mixture was reacted for 3 hours, and it was confirmed that the isocyanate value was 0.6 or less. Thereafter, the temperature was raised to 90 ° C., and methyl ethyl ketone was removed by distillation under reduced pressure until the solid content concentration became 81.7%. After the removal, 659 g of propylene glycol monomethyl ether and 270 g of deionized water were added and diluted to obtain a polyalkylene glycol-modified epoxy resin solution A1 having a solid content concentration of 76%.
[0138]
・ Production of aqueous epoxy resin dispersion
<Production Example 2>
2029 g of EP1004 (epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 1000) and 697 g of propylene glycol monobutyl ether were charged into a four-necked flask, and the temperature was raised to 110 ° C., and the epoxy resin was completely dissolved in one hour. 1180 g of the polyalkylene glycol-modified epoxy resin solution A1 obtained in Production Example 1 and 311.7 g of 3-amino-1,2,4-triazole (molecular weight: 84) were added thereto, and the mixture was reacted at 100 ° C. for 5 hours. And 719.6 g of propylene glycol monobutyl ether were added to obtain a resin solution D1.
To 257.6 g of the above resin solution D1, 50 g of MF-K60X (isocyanate curing agent, manufactured by Asahi Kasei Kogyo Co., Ltd.) and 0.3 g of Scat 24 (curing catalyst) were mixed, and after stirring well, 692.1 g of water was added dropwise little by little. After mixing and stirring, an aqueous epoxy resin dispersion E1 was obtained.
[0139]
<Production Example 3> (Aqueous epoxy resin dispersion containing no hydrazine derivative)
2029 g of EP1004 (epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 1000) and 697 g of propylene glycol monobutyl ether were charged into a four-necked flask, and the temperature was raised to 110 ° C., and the epoxy resin was completely dissolved in one hour. To this, 1180 g of the polyalkylene glycol-modified epoxy resin solution A1 obtained in Production Example 1 and 527.0 g of propylene glycol monobutyl ether were added to obtain a resin solution D2.
To 257.6 g of the resin solution D2, 50 g of MF-K60X (isocyanate curing agent, manufactured by Asahi Kasei Kogyo Co., Ltd.) and 0.3 g of Scat24 (curing catalyst) were mixed and stirred well, and 692.1 g of water was added dropwise and mixed little by little. The mixture was stirred to obtain an aqueous epoxy resin dispersion E2.
[0140]
As the coating composition for forming the second layer, a resin composition shown in Table 7 was used, and a chromium-free rust-preventive additive (Table 6) and a solid lubricant (Table 8) were appropriately blended with the resin composition. The mixture was stirred for a predetermined time by using a dispersing machine (sand grinder) to prepare a coating composition. The base resin (reaction product) of the resin composition shown in Table 7 was synthesized as follows.
<Synthesis example 1>
1870 parts of EP828 (manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 187), 912 parts of bisphenol A, 2 parts of tetraethylammonium bromide, and 300 parts of methyl isobutyl ketone are charged into a four-necked flask, heated to 140 ° C., and reacted for 4 hours. Thus, an epoxy resin having an epoxy equivalent of 1391 and a solid content of 90% was obtained. To this, 1500 parts of ethylene glycol monobutyl ether was added, and the mixture was cooled to 100 ° C. 96 parts of 3,5-dimethylpyrazole (molecular weight: 96) and 129 parts of dibutylamine (molecular weight: 129) were added to eliminate the epoxy group. After reacting for 6 hours, 205 parts of methyl isobutyl ketone was added while cooling to obtain a pyrazole-modified epoxy resin having a solid content of 60%. This is referred to as a resin composition (1). This resin composition (1) is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound containing 50 mol% of a hydrazine derivative (G) having active hydrogen.
[0141]
<Synthesis Example 2>
4000 parts of EP1007 (made by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 2000) and 2239 parts of ethylene glycol monobutyl ether were charged into a four-necked flask, heated to 120 ° C. and completely dissolved the epoxy resin in one hour. This was cooled to 100 ° C., 168 parts of 3-amino-1,2,4-triazole (molecular weight 84) was added, and the mixture was reacted for 6 hours until the epoxy group disappeared. Then, a triazole-modified epoxy resin having a solid content of 60% was obtained. This is referred to as a resin composition (2). This resin composition (2) is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound containing 100 mol% of a hydrazine derivative (G) having active hydrogen.
[0142]
<Synthesis example 3>
A four-necked flask is charged with 222 parts of isophorone diisocyanate (isocyanate equivalent weight: 111) and 34 parts of methyl isobutyl ketone, and 87 parts of methyl ethyl ketoxime (molecular weight: 87) is added dropwise over 3 hours while maintaining the temperature at 30 to 40 ° C. By keeping the time, a partially blocked isocyanate having an isocyanate equivalent of 309 and a solid content of 90% was obtained.
Next, 1496 parts of EP828 (manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 187), 684 parts of bisphenol A, 1 part of tetraethylammonium bromide, and 241 parts of methyl isobutyl ketone were charged into a four-necked flask, and heated to 140 ° C. for 4 hours. The reaction was performed to obtain an epoxy resin having an epoxy equivalent of 1090 and a solid content of 90%. To this, 1000 parts of methyl isobutyl ketone was added, and the mixture was cooled to 100 ° C., 202 parts of 3-mercapto-1,2,4-triazole (molecular weight: 101) was added, and the mixture was reacted for 6 hours until the epoxy group disappeared. After that, 230 parts of the above partially blocked isocyanate having a solid content of 90% was added and reacted at 100 ° C. for 3 hours, and it was confirmed that the isocyanate group had disappeared. Further, 461 parts of ethylene glycol monobutyl ether was added to obtain a modified triazole epoxy resin having a solid content of 60%. This is referred to as a resin composition (3). This resin composition (3) is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound containing 100 mol% of a hydrazine derivative (G) having active hydrogen.
[0143]
<Synthesis example 4>
1870 parts of EP828 (manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 187), 912 parts of bisphenol A, 2 parts of tetraethylammonium bromide, and 300 parts of methyl isobutyl ketone were charged into a four-necked flask, heated to 140 ° C., and reacted for 4 hours. Thus, an epoxy resin having an epoxy equivalent of 1391 and a solid content of 90% was obtained. After adding 1500 parts of ethylene glycol monobutyl ether, the mixture was cooled to 100 ° C., 258 parts of dibutylamine (molecular weight: 129) was added, and the mixture was reacted for 6 hours until the epoxy group disappeared. 225 parts of ketone was added to obtain an epoxyamine adduct having a solid content of 60%. This is referred to as a resin composition (4). This resin composition (4) is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound that does not contain a hydrazine derivative (G) having active hydrogen.
[0144]
Plated steel sheets shown in Table 1, which are plated steel sheets for home appliances, building materials, and automobile parts based on cold-rolled steel sheets, were used as processing base sheets. In addition, the thing of predetermined | prescribed sheet thickness was employ | adopted for the plate thickness of the steel plate according to the objective of evaluation. After the surface of the plated steel sheet was subjected to alkali degreasing treatment, washing and drying, the surface treatment composition for forming the first layer was applied by a roll coater, and dried by heating at various temperatures. The film thickness of the film was adjusted according to the solid content of the surface treatment composition (residual residue after heating) or the application conditions (roll rolling force, rotation speed, etc.).
Next, the coating composition for forming the second layer was applied by a roll coater and dried by heating at various temperatures. The film thickness of the coating was adjusted by the solid content (heating residue) of the coating composition or the coating conditions (roll rolling force, rotation speed, etc.).
[0145]
Tables 9 to 22 show the results of evaluating the coating composition and the quality performance (corrosion resistance, corrosion resistance after processing, weldability, electrodeposition coating property) of the obtained surface-treated steel sheet. The quality performance was evaluated as follows.
(1) Corrosion resistance
Each sample was subjected to the following combined cycle test (CCT), and evaluated by a white rust generation area ratio and a red rust generation area ratio after 30 cycles.
Salt spray (based on JIS Z 2371): 4 hours
↓
Drying (60 ° C): 2 hours
↓
Wet (50 ° C., 95% RH): 2 hours
The evaluation criteria are as follows.
◎: Area ratio of white rust occurrence less than 10%
：: White rust generation area ratio 10% or more and less than 30%
○-: No red rust was generated when the area ratio of white rust was 30% or more.
Δ: Red rust occurred, red rust occurrence area ratio less than 10%
×: Area ratio of red rust occurrence 10% or more
[0146]
(2) Corrosion resistance after processing
Deformation and sliding were applied to each sample with a draw bead under the following conditions, and the sample was degreased at 45 ° C. for 2 minutes using “FC-4460” manufactured by Nippon Parkerizing Co., Ltd. The CCT performed in the above-mentioned “(1) Corrosion resistance” was performed, and the area ratio of white rust occurrence and red rust occurrence area after 18 cycles was evaluated.
Pressing load: 800kgf
Drawing speed: 1000 mm / min
Bead shoulder R: Male side 5mmR, female side 5mmR
Indentation depth: 7mm
Oil used: Preton R-352L
The evaluation criteria are as follows.
◎: Area ratio of white rust occurrence less than 10%
：: White rust generation area ratio 10% or more and less than 30%
○-: White rust generation area ratio is 30% or more, no red rust generation
Δ: Red rust occurred, red rust occurrence area ratio less than 10%
×: Area ratio of red rust occurrence 10% or more
[0147]
(3) Weldability
For each sample, a continuous spot welding test was performed under the conditions of an electrode used: a CF-type Cr-Cu electrode, a pressing force of 200 kgf, a conduction time of 10 cycles / 50 Hz, and a welding current of 10 kA, and the number of continuous spots was evaluated. The evaluation criteria are as follows.
◎: 2000 points or more
: 1000 points or more and less than 2000 points
Δ: 500 points or more and less than 1000 points
×: Less than 500 points
(4) Electrocoatability
Each sample was coated with a cationic electrodeposition paint (“GT-10” manufactured by Kansai Paint Co., Ltd.) to a film thickness of 30 μm, and baked at 130 ° C. for 30 minutes. The coated sample was immersed in boiling water for 2 hours, immediately cut in a grid (10 × 10 pieces, 1 mm interval), adhered and peeled off with an adhesive tape, and the peeling area ratio of the coating film was measured. The evaluation criteria are as follows.
◎: No peeling
：: Peeling area ratio less than 5%
Δ: Peeling area ratio 5% or more and less than 20%
X: Peeling area ratio of 20% or more
[0148]
[Table 1]

[0149]
[Table 2]

[0150]
[Table 3]

[0151]
[Table 4]

[0152]
[Table 5]

[0153]
[Table 6]

[0154]
[Table 7]

[0155]
[Table 8]

[0156]
In addition, * 1 to * 10 described in Tables 9 to 22 indicate the following contents.
* 1: No. described in Table 1. (Plated steel sheet)
* 2: No. described in Table 2. (Water-soluble or water-dispersible epoxy resin)
* 3: No. described in Table 3. (Silane coupling agent)
* 4: No. described in Table 4 (Phosphoric acid or hexafluorometallic acid)
* 5: No. described in Table 5 (Water-soluble phosphate)
* 6: No. described in Table 6 (Anti-rust additive)
* 7: parts by mass (for components other than the water-soluble or water-dispersible epoxy resin, parts by mass based on 100 parts by mass of the solid content of the water-soluble or water-dispersible epoxy resin)
* 8: No. described in Table 7 (Resin composition)
* 9: No. described in Table 8 (Solid lubricant)
* 10: parts by mass (for components other than organic resin, parts by mass based on 100 parts by mass of solid content of organic resin)
[0157]
[Table 9]

[0158]
[Table 10]

[0159]
[Table 11]

[0160]
[Table 12]

[0161]
[Table 13]

[0162]
[Table 14]

[0163]
[Table 15]

[0164]
[Table 16]

[0165]
[Table 17]

[0166]
[Table 18]

[0167]
[Table 19]

[0168]
[Table 20]

[0169]
[Table 21]

[0170]
[Table 22]

[0171]
[Example 2]
In Examples 1 to 3 of the present invention, for No. 1 surface treatment film, No. 1 in Table 3 with respect to the aqueous epoxy resin dispersion of No. 1. No. 1 in Table 2 was used in Comparative Examples. A surface treatment composition consisting only of the aqueous epoxy resin dispersion of No. 1 was used. The surface treatment compositions were subjected to alkali degreasing treatment, washing with water, and drying. The coated steel sheet No. 1 was applied by a roll coater and dried by heating at 140 ° C. to form a surface-treated film having a thickness of 0.5 μm. Then, for the upper layer film of the second layer, both of the present invention example and the comparative example were No. 1 of [Example 1]. Using the same coating composition as in Table 3 (Table 10), this coating composition was applied on the surface treatment film as the first layer with a roll coater, and dried by heating at 140 ° C. to form an upper layer having a thickness of 1.5 μm. A film was formed.
[0172]
The obtained surface-treated steel sheet was evaluated for corrosion resistance and corrosion resistance after processing under the same test conditions and evaluation criteria as in [Example 1]. The results are shown in Table 23 together with the film configurations of the first and second layers.
・ Comparative example
In the comparative examples in Table 23, the first layer surface treatment film was composed only of the organic resin barrier layer, and thus the corrosion resistance and the post-process corrosion resistance were insufficient.
FIG. 1 shows an electron micrograph (bright field image) of a film cross section of a film corresponding to the surface treatment film of the comparative example. The preparation and measurement of the sample were performed under the conditions described above.
[0173]
・ Example 1 of the present invention
Inventive Example 1 in Table 23 has excellent corrosion resistance and post-work corrosion resistance as compared with Comparative Examples.
FIG. 2 shows an electron micrograph (bright field image) of a cross section of a film corresponding to the surface treatment film of Example 1 of the present invention, and FIG. Note that the description of the C concentration is omitted because most of the concentration is overscaled (the same applies to FIGS. 5 and 7 described later). The preparation and measurement of the sample were performed under the conditions described above (the same applies to FIGS. 4 to 7 described later). According to these, a surface treatment film composed of a compound layer (amorphous compound layer) containing P, Zn and O and equimolar amounts of Zn and P in the lower part, and an organic resin matrix layer in the upper part is formed. It turns out that there is. According to the electron diffraction pattern, the compound layer is amorphous. In FIG. 3 (the same applies to FIGS. 5 and 7 described later), the separation of Zn and P in the compound layer from equimolar to Zn-rich on the zinc plating film side is because the probe diameter of the electron beam is finite. (The effect of the zinc plating layer itself and the compound layer being simultaneously included in the probe diameter at the compound layer / plating layer interface).
[0174]
・ Example 2 of the present invention
Inventive Example 2 of Table 23 has more excellent corrosion resistance and post-work corrosion resistance than Inventive Example 1.
FIG. 4 shows an electron micrograph (bright-field image) of a cross section of a film corresponding to the surface-treated film of Example 2 of the present invention. The arrows in FIG. FIG. 5 shows the results of composition analysis of the cross section of the film (downward arrows in the graph correspond to the positions of the precipitated compounds), respectively. According to these, a compound layer (an amorphous compound layer) containing P, Zn, and O and containing equimolar Zn and P is formed in the lower layer portion of the surface treatment film in the same manner as in Example 1 of the present invention. I have. Further, in Example 2 of the present invention, a compound containing P, Zn and O is precipitated in the surface treatment film. According to the electron diffraction pattern, the compound layer and the precipitated compound are in an amorphous state.
[0175]
・ Example 3 of the present invention
Inventive Example 3 in Table 23 has more excellent corrosion resistance and post-work corrosion resistance than Inventive Example 2.
FIG. 6 is an electron micrograph (bright field image) of a cross section of a film corresponding to the surface treatment film of Example 3 of the present invention. The arrows in FIG. FIG. 7 shows the results of composition analysis of the cross section of the film (downward arrows in the graph correspond to the positions of the precipitated compounds). According to these, similarly to Examples 1 and 2 of the present invention, a compound layer (amorphous compound layer) containing P, Zn, and O and containing equimolar amounts of Zn and P is formed in the lower layer portion of the surface treatment film. Have been. Further, in Example 3 of the present invention, a compound containing Zn, P, Si and O was precipitated in the surface treatment film. Further, these deposited compounds have a molar ratio [Zn] / [P] of Zn and P of less than 1.0. According to the electron diffraction pattern, the compound layer and the precipitated compound are in an amorphous state.
[0176]
[Table 23]

[0177]
* 1 to * 7 described in Table 23 indicate the following contents.
* 1: No. described in Table 2. (Water-dispersible epoxy resin)
* 2: No. described in Table 3 (Silane coupling agent)
* 3: No. described in Table 4 (Phosphoric acid or hexafluorometallic acid)
* 4: parts by mass (for components other than the water-dispersible epoxy resin, parts by mass with respect to 100 parts by mass of the solid content of the water-dispersible epoxy resin)
* 5: No. described in Table 7 (Resin composition)
* 6: No. described in Table 6 (Anti-rust additive)
* 7: parts by mass (for rust preventive additives, parts by mass based on 100 parts by mass of solid content of organic resin)
[0178]
【The invention's effect】
As described above, the surface-treated steel sheet of the present invention has a very excellent flat plate and corrosion resistance after processing, even though it does not contain chromium in the film, and also has excellent weldability and paintability. Therefore, the surface-treated steel sheet of the present invention is particularly useful for automotive applications.
[Brief description of the drawings]
FIG.
Electron microscope enlarged photograph of the cross-sectional structure of the film corresponding to the surface-treated film of the surface-treated steel sheet of the comparative example in [Example 2].
FIG. 2
Electron microscope enlarged photograph of the cross-sectional structure of the film corresponding to the surface-treated film of the surface-treated steel sheet of Example 1 of the present invention in [Example 2].
FIG. 3
Graph showing the composition analysis result of the cross-section of the film corresponding to the surface-treated film of the surface-treated steel sheet of Example 1 of the present invention in [Example 2].
FIG. 4
Electron microscope enlarged photograph of the film cross-sectional structure of the film corresponding to the surface-treated steel sheet of Example 2 of the present invention in [Example 2].
FIG. 5
Graph showing the composition analysis result of the cross-section of the film corresponding to the surface-treated film of the surface-treated steel sheet of Example 2 of the present invention in [Example 2].
FIG. 6
Electron microscope enlarged photograph of the cross-sectional structure of the film corresponding to the surface-treated film of the surface-treated steel sheet of Example 3 of the present invention in [Example 2].
FIG. 7
Graph showing the composition analysis result of the cross-section of the film corresponding to the surface-treated film of the surface-treated steel sheet of Example 3 of the present invention in [Example 2].

Claims (25)

A surface treatment composition containing the following components (a) to (c) is applied to the surface of a galvanized steel sheet or an aluminum-plated steel sheet, and the thickness of the film formed by drying is 0.01 to 1.0 μm. To form a surface treatment film of
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol-type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion (b) obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water (b) silane Coupling agent: 1 to 300 parts by mass per 100 parts by mass of the solid content of the aqueous epoxy resin dispersion (c) Phosphoric acid and / or hexafluorometallic acid: To 100 parts by mass of the solid content of the aqueous epoxy resin dispersion On the other hand, the main component of the resin composition is 0.1 to 80 parts by mass, (E) and a reaction product of an active hydrogen-containing compound (F) comprising a hydrazine derivative (G) in which some or all of the compounds have active hydrogen, and a film thickness of 0.5 to 2.0 μm. A highly corrosion-resistant surface-treated steel sheet characterized by forming a surface. A surface treatment composition containing components (a) to (c) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and dried to form a coating having a thickness of 0.01 to 1.0 μm. Form a surface treatment film,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol-type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified It is obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A), a hydrazine derivative (C) having an active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C). Aqueous epoxy resin dispersion obtained by dispersing resin in water (b) Silane coupling agent: 1 to 300 parts by mass per 100 parts by mass of solid content of the aqueous epoxy resin dispersion (c) Phosphoric acid and / or hexagon Fluorometallic acid: 0.1 to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion. In the upper layer, the main component of the resin composition is a film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet comprising a reaction product and having an upper layer film having a thickness of 0.5 to 2.0 μm. The epoxy group-containing resin (B) for obtaining the aqueous epoxy resin dispersion of the component (a) is a bisphenol A type epoxy resin having an epoxy equivalent of 150 to 5,000, and has a number average molecular weight of 1500 to 10,000. The high corrosion-resistant surface-treated steel sheet according to claim 1 or 2. The highly corrosion-resistant surface-treated steel sheet according to claim 1, 2 or 3, wherein the aqueous epoxy resin dispersion of the component (a) further contains a curing agent having a group that crosslinks with a hydroxyl group. The surface treatment composition for forming a surface treatment film further comprises a water-soluble phosphate in an amount of 0.1 to 60 parts by mass based on 100 parts by mass of the solid content of the aqueous epoxy resin dispersion of the component (a). The highly corrosion-resistant surface-treated steel sheet according to claim 1, 2, 3 or 4. Surface treatment composition for surface treatment film formation, as the water-soluble phosphate, the molar ratio of the cationic components and _P 2 _{O 5} component [cation] _{/ [P} 2 _{O 5]} is 0.4 to 1.0 met The highly corrosion-resistant surface-treated steel sheet according to claim 5, characterized in that the high-corrosion-resistant surface-treated steel sheet according to claim 5, further comprising a water-soluble phosphate in which the cation species is at least one selected from Mn, Mg, Al, and Ni. The surface treatment composition for forming a surface treatment film further comprises a chromium-free rust-preventive additive in an amount of 0.1 to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion of the component (a). The highly corrosion-resistant surface-treated steel sheet according to claim 1, wherein the steel sheet contains 50 parts by mass. The upper layer coating further contains 0.1 to 50 parts by mass of a non-chromium-based rust-preventive additive in a ratio of solids to 100 parts by mass of solids of the resin composition. The high corrosion-resistant surface-treated steel sheet according to 3, 4, 5, 6, or 7. The surface treatment composition for forming the surface treatment film and / or the upper film contains one or more rust preventive additives selected from the following (e1) to (e5) as non-chromium rust preventive additives. The high corrosion-resistant surface-treated steel sheet according to claim 7 or 8, wherein:
(E1) silicon oxide (e2) calcium and / or calcium compound (e3) sparingly soluble phosphate compound (e4) molybdate compound (e5) selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atoms The silane coupling agent of the component (b) contains at least one silane coupling agent having an amino group as a reactive functional group. The high corrosion-resistant surface-treated steel sheet according to 7, 8, or 9. The upper layer coating further contains 1 to 30 parts by mass of a solid lubricant in a ratio of a solid content to 100 parts by mass of the solid content of the resin composition. , 6, 7, 8, 9 or 10. (X) an amorphous compound layer containing P, Zn or / and Al and O on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet; A polyalkylene glycol-modified epoxy resin (A) obtained by reacting 20,000 polyalkylene glycol, a bisphenol-type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and an epoxy other than the polyalkylene glycol-modified epoxy resin (A) The organic resin matrix layer having a matrix of a water-dispersible resin obtained by reacting a group-containing resin (B) with a hydrazine derivative (C) having active hydrogen, and having a film thickness of 0.01 to Having a surface treatment film of 1.0 μm,
In the upper layer, the main component of the resin composition is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet comprising an upper layer film having a thickness of 0.5 to 2.0 μm. (X) an amorphous compound layer containing P, Zn or / and Al and O on the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet; A polyalkylene glycol-modified epoxy resin (A) obtained by reacting 20,000 polyalkylene glycol, a bisphenol-type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and an epoxy other than the polyalkylene glycol-modified epoxy resin (A) A water-dispersible resin obtained by reacting a group-containing resin (B), a hydrazine derivative (C) having active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C) is used as a matrix. Surface-treated skin having a film thickness of 0.01 to 1.0 μm, comprising an organic resin matrix layer Have,
In the upper layer, the main component of the resin composition is a reaction product of a film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A highly corrosion-resistant surface-treated steel sheet comprising an upper layer film having a thickness of 0.5 to 2.0 μm. The highly corrosion-resistant surface-treated steel sheet according to claim 12, wherein the surface-treated film further contains a silane compound. The highly corrosion-resistant surface-treated steel sheet according to claim 12, 13 or 14, wherein the surface-treated film contains a precipitated compound containing P, Zn or / and Al and O. The highly corrosion-resistant surface-treated steel sheet according to claim 12, 13, 14 or 15, wherein the surface-treated film contains a precipitated compound containing P, Zn or / and Al, Si and O. A surface-treated steel sheet having a surface-treated film on a surface of a galvanized steel sheet and an upper layer film thereon, wherein the molar ratio [Zn] / [P] of Zn and P in the amorphous compound layer is 0. The highly corrosion-resistant surface-treated steel sheet according to claim 12, 13, 14, 15, or 16, wherein the thickness is from 0.9 to 1.4. A surface-treated steel sheet having a surface-treated film on the surface of a zinc-based plated steel sheet and having an upper layer film thereon, wherein the molar ratio of Zn to P in the precipitated compound contained in the surface-treated film [Zn] / [P ] Is 0.9-1.4, The high corrosion-resistant surface-treated steel plate of Claim 15, 16 or 17 characterized by the above-mentioned. A surface-treated steel sheet having a surface-treated film on the surface of a zinc-based plated steel sheet and having an upper layer film thereon, wherein the molar ratio of Zn to P in the precipitated compound contained in the surface-treated film [Zn] / [P ] Is less than 1.0, the highly corrosion-resistant surface-treated steel sheet according to claim 15, 16 or 17. The surface treatment film further contains 0.1 to 50 parts by mass of a non-chromium-based rust-preventive additive in a ratio of solids to 100 parts by mass of solids of the organic resin. , 14, 15, 16, 17, 18 or 19. The upper layer coating further contains 0.1 to 50 parts by mass of a non-chromium-based rust-preventive additive in a ratio of solids to 100 parts by mass of solids of the resin composition. , 14, 15, 16, 17, 18, 19, or 20. 21. The surface treatment film and / or the upper film contains one or more rust preventive additives selected from the following (e1) to (e5) as non-chromium rust preventive additives. Or a highly corrosion-resistant surface-treated steel sheet according to item 21.
(E1) silicon oxide (e2) calcium and / or calcium compound (e3) sparingly soluble phosphate compound (e4) molybdate compound (e5) selected from triazoles, thiols, thiadiazoles, thiazoles, thiurams One or more organic compounds containing S atoms The upper layer coating further contains 1 to 30 parts by mass of a solid lubricant in a ratio of a solid content to 100 parts by mass of a solid content of the resin composition. , 17, 18, 19, 20, 21 or 22. A surface treatment composition containing the following components (a) to (c) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and dried at a temperature of 30 to 150 [deg.] C. to reach a film thickness. Forms a surface treatment film of 0.01 to 1.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol-type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified An aqueous epoxy resin dispersion (b) obtained by dispersing a resin obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A) with a hydrazine derivative (C) having active hydrogen in water (b) silane Coupling agent: 1 to 300 parts by mass per 100 parts by mass of the solid content of the aqueous epoxy resin dispersion (c) Phosphoric acid and / or hexafluorometallic acid: To 100 parts by mass of the solid content of the aqueous epoxy resin dispersion 0.1-80 parts by mass relative to the upper layer, the main component of the resin composition is a film-forming organic resin E) and a coating composition comprising a reaction product of an active hydrogen-containing compound (F) comprising a hydrazine derivative (G) in which some or all of the compounds have active hydrogen, is applied, and the reached plate temperature is 30 to 150 ° C. A method for producing a high corrosion resistant surface-treated steel sheet, wherein an upper layer film having a thickness of 0.5 to 2.0 μm is formed by drying at a temperature of 0.5 to 2.0 μm. A surface treatment composition containing the following components (a) to (c) is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and dried at a temperature of 30 to 150 [deg.] C. to reach a film thickness. Forms a surface treatment film of 0.01 to 1.0 μm,
(A) a polyalkylene glycol-modified epoxy resin (A) obtained by reacting a polyalkylene glycol having a number average molecular weight of 400 to 20,000, a bisphenol-type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, and the polyalkylene glycol-modified It is obtained by reacting an epoxy group-containing resin (B) other than the epoxy resin (A), a hydrazine derivative (C) having an active hydrogen, and an active hydrogen-containing compound (D) other than the hydrazine derivative (C). Aqueous epoxy resin dispersion obtained by dispersing resin in water (b) Silane coupling agent: 1 to 300 parts by mass per 100 parts by mass of solid content of the aqueous epoxy resin dispersion (c) Phosphoric acid and / or hexagon Fluorometallic acid: 0.1 to 8 with respect to 100 parts by mass of the solid content of the aqueous epoxy resin dispersion. In the upper part by mass, the main component of the resin composition is a reaction between the film-forming organic resin (E) and an active hydrogen-containing compound (F) composed of a hydrazine derivative (G) in which some or all of the compounds have active hydrogen. A high-corrosion-resistant surface treatment characterized in that a coating composition comprising the product is applied and the ultimate plate temperature is dried at a temperature of 30 to 150 ° C. to form an upper layer film having a thickness of 0.5 to 2.0 μm. Steel plate manufacturing method.

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