JP2004269921A

JP2004269921A - Method for manufacturing steel sheet provided with organic composite coating film

Info

Publication number: JP2004269921A
Application number: JP2003059122A
Authority: JP
Inventors: Kotaro Okamoto; 幸太郎岡本; Satoshi Ando; 聡安藤; Shigeki Nabe; 茂樹名部
Original assignee: JFE Steel Corp
Current assignee: JFE Steel Corp
Priority date: 2003-03-05
Filing date: 2003-03-05
Publication date: 2004-09-30

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a uniform surface appearance on the steel sheet provided with an organic composite coating film, when manufacturing it by forming an organic composite coating film comprising an underlayer formed through applying a liquid containing an oxide and phosphoric acid and/or a phosphate compound, and an upper layer formed of a resin coating film thereon. <P>SOLUTION: The method for manufacturing the steel sheet provided with the organic composite coating film comprises applying a treatment liquid containing phosphoric acid and/or a phosphate compound on a galvanized steel sheet or an aluminized steel sheet lower than 50°C, then drying and heating it to form a coating film containing phosphoric acid with a thickness of 0.005 to 4 μm, and forming an organic coating film having a thickness of 0.1 to 5 μm thereon. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、下層に酸化物を含有するリン酸及び／又はリン酸化合物皮膜、その上層に樹脂皮膜からなる有機複合被覆を形成させる有機複合被覆鋼板の製造方法に関する。より具体的には、下層に起源する外観むらの発生しない、下層に酸化物を含有するリン酸及び／又はリン酸化合物皮膜、その上層に樹脂皮膜からなる有機複合被覆を形成させる有機複合被覆鋼板の製造方法に関する。
【０００２】
【従来の技術】
亜鉛系めっき鋼板のクロメート処理は、亜鉛の白錆を抑制する安価な防錆処理方法として幅広く使用されている。一方、クロメート処理液は６価クロムが含まれるため、従来から環境対策として、クロメート処理時の完全クローズドシステムによる排水処理の採用や、水洗工程を必要としない塗布型クロメート処理技術の開発が行われている。また、クロメート皮膜が微量に含有する６価クロムについても、クロム溶出を防止した有機複合被覆鋼板の開発、塗布型クロメート皮膜の難溶化の検討などが行われてきた。
【０００３】
一方、環境対策面から、６価クロムを使用しないクロムフリー化成処理鋼板の開発が行われ、例えば、以下のような方法が提案されている。
（１）タンニン酸を用いる方法（例えば、特許文献１）
（２）エポキシ樹脂とアミノ樹脂とタンニン酸を混合した熱硬化性塗料を用いる方法（例えば、特許文献２）
（３）水系樹脂と多価フェノールカルボン酸の混合組成物を用いる方法（例えば、特許文献３）
（４）ヒドラジン誘導体水溶液をブリキまたは亜鉛鉄板の表面に塗布する表面処理方法（例えば、特許文献４）
（５）水酸基含有モノマーを共重合成分として含有する有機樹脂とリン酸、金属のリン酸系化合物からなる表面処理用組成物を用いる方法（例えば、特許文献５）
（６）下層に酸化物を含有するリン酸及び／又はリン酸化合物皮膜、その上層に樹脂皮膜からなる有機複合被覆を形成させる方法（例えば、特許文献６、特許文献７）
以下に先行技術文献情報について記載する。
【０００４】
【特許文献１】
特開昭５１−７１２３３号公報
【０００５】
【特許文献２】
特開昭６３−９０５８１号公報
【０００６】
【特許文献３】
特開平８−３２５７６０号公報
【０００７】
【特許文献４】
特公昭５６−１０３８６号公報
【０００８】
【特許文献５】
特開平９−２０８８５９号公報
【０００９】
【特許文献６】
特開２００１−１１６４５号公報
【００１０】
【特許文献７】
特開２００１−１１６５６号公報
【００１１】
【発明が解決しようとする課題】
上記の中で、（６）の下層に酸化物を含有するリン酸及び／又はリン酸化合物皮膜、その上層に樹脂皮膜からなる有機複合被覆を形成させる有機複合被覆鋼板は、従来のクロメート処理鋼板に充分代替出来る特性を有している。しかしながら、酸化物を含有するリン酸及び／又はリン酸化合物皮膜を形成させる工程において、安定して均一な表面外観が得難いという問題がある。
【００１２】
本発明は、前記事情を考慮し、下層に酸化物を含有するリン酸及び／又はリン酸化合物皮膜、その上層に樹脂皮膜からなる有機複合被覆を形成させて有機複合被覆鋼板を製造するに際し、下層に起源する外観むらの発生しない表面外観に優れる有機複合被覆鋼板鋼板の製造方法を提供することを目的とする。
【００１３】
【課題を解決するための手段】
本発明者らは、前記した下層に酸化物を含有するリン酸及び／又はリン酸化合物皮膜、その上層に樹脂皮膜からなる有機複合被覆を形成させる有機複合被覆鋼板の製造方法において、安定して均一な表面外観が得られる方法に関して検討を行い、下層を形成する時の処理条件、具体的には下層を形成する時の鋼板温度及び／又は処理液温度を特定の範囲に限定することによって、外観むらを発生させずに安定して良好な表面外観が得られることを見いだした。本発明はこの知見に基づきなされた。
【００１４】
上記課題を解決する本発明の手段は次の通りである。
【００１５】
（１）温度５０℃未満の亜鉛系めっき鋼板またはアルミニウム系めっき鋼板にリン酸及び／又はリン酸化合物を含有する処理液を塗布し、しかる後、乾燥加熱して、膜厚が０．００５〜４μｍのリン酸含有皮膜を形成し、その上層に０．１〜５μｍの有機皮膜を形成させることを特徴とする有機複合被覆鋼板の製造方法。
【００１６】
（２）温度２５℃以下のリン酸及び／又はリン酸化合物を含有する処理液を亜鉛系めっき鋼板またはアルミニウム系めっき鋼板表面に塗布し、しかる後、乾燥加熱して、膜厚が０．００５〜４μｍのリン酸含有皮膜を形成し、その上層に０．１〜５μｍの有機皮膜を形成させることを特徴とする有機複合被覆鋼板の製造方法。
【００１７】
（３）温度５０℃未満の亜鉛系めっき鋼板またはアルミニウム系めっき鋼板表面に、温度２５℃以下のリン酸及び／又はリン酸化合物を含有する処理液を塗布し、しかる後、乾燥加熱して、膜厚が０．００５〜４μｍのリン酸含有皮膜を形成し、その上層に０．１〜５μｍの有機皮膜を形成させることを特徴とする有機複合被覆鋼板の製造方法。
【００１８】
（４）リン酸及び／又はリン酸化合物を含有する処理液が、さらに酸化物微粒子、及び、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｍｎ、Ａｌ、Ｆｅの各金属イオン、前記金属のうちの少なくとも１種を含む水溶性イオン、前記金属のうちの少なくとも１種を含む化合物、前記金属のうちの少なくとも１種を含む複合化合物の中から選ばれる１種以上を含むことを特徴とする（１）〜（３）のいずれかに記載の有機複合被覆鋼板の製造方法。
【００１９】
（５）リン酸及び／又はリン酸化合物を含有し、さらに酸化物微粒子、及び、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｍｎ、Ａｌ、Ｆｅの各金属イオン、前記金属のうちの少なくとも１種を含む水溶性イオン、前記金属のうちの少なくとも１種を含む化合物、前記金属のうちの少なくとも１種を含む複合化合物の中から選ばれる１種以上を含有する処理液が、リン酸及び／又はリン酸化合物をＰ_２Ｏ_５換算量で０．００１〜６．０モル／Ｌ含有し、さらに酸化物微粒子を０．００１〜３．０モル／Ｌ、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｍｎ、Ａｌ、Ｆｅの各金属イオン、前記金属のうちの少なくとも１種を含む水溶性イオン、前記金属のうちの少なくとも１種を含む化合物、前記金属のうちの少なくとも１種を含む複合化合物の中から選ばれる１種以上を、前記金属の金属量換算の合計で０．００１〜３．０モル／Ｌ含有するｐＨ０．５〜５の酸性水溶液であることを特徴とする（４）に記載の有機複合被覆鋼板の製造方法。
【００２０】
【発明の実施の形態】
本発明において、有機被覆鋼板のベースとなる亜鉛系めっき鋼板としては、亜鉛めっき鋼板、Ｚｎ−Ｎｉ合金めっき鋼板、Ｚｎ−Ｆｅ合金めっき鋼板（電気めっき鋼板および合金化溶融亜鉛めっき鋼板）、Ｚｎ−Ａｌ合金めっき鋼板（例えば、Ｚｎ−５％Ａｌ合金めっき鋼板、Ｚｎ−５５％Ａｌ合金めっき鋼板）などを用いることができる。また、本発明の有機被覆鋼板のベースとなるアルミニウム系めっき鋼板としては、アルミニウムめっき鋼板、Ａｌ−Ｓｉ合金めっき鋼板などを用いることができる。
【００２１】
本発明では、前記ベースとなる亜鉛系めっき鋼板またはアルミニウム系めっき鋼板に、リン酸及び／又はリン酸化合物を含有する処理液を塗布し、しかる後、乾燥加熱して、下層のリン酸含有皮膜を形成し、その上層に有機皮膜を形成する。
【００２２】
下層のリン酸塩含有皮膜の形成に用いるリン酸及び／又はリン酸化合物を含有する処理液は、（イ）リン酸及び／又はリン酸化合物を含み、または、さらに（ロ）酸化物微粒子と、（ハ）Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｍｎ、Ａｌ、Ｆｅの各金属イオン、前記金属のうちの少なくとも１種を含む水溶性イオン、前記金属のうちの少なくとも１種を含む化合物、前記金属のうちの少なくとも１種を含む複合化合物の中から選ばれる１種以上と、を含有する処理液である。
【００２３】
前記成分（イ）であるリン酸及び／又はリン酸化合物はとしては、オルトリン酸、ピロリン酸、トリポリリン酸などのポリリン酸、メタリン酸及びこれらの無機塩（例えば、第一リン酸アルミニウムなど）、亜リン酸、亜リン酸塩、次亜リン酸、次亜リン酸塩などのリン酸含有の化合物が、水溶液中で溶解した際に生じるアニオン、あるいは金属カチオンとの錯イオンとして存在している形態、遊離酸として存在している形態など全てを含み、本発明におけるリン酸成分の量は酸性水溶液中で存在するこれら全ての形態の合計をＰ_２Ｏ_５換算として規定する。
【００２４】
処理液中でのリン酸及び／又はリン酸化合物の添加量はＰ_２Ｏ_５換算で０．００１〜６．０モル／Ｌ、好ましくは０．０２〜１．０モル／Ｌ、さらに好ましくは０．１〜０．８モル／Ｌとする。リン酸及び／又はリン酸化合物の添加量が０．００１モル／Ｌ未満では添加による効果が十分でなく、耐食性が劣る。一方、添加量が６．０モル／Ｌを超えると過剰のリン酸イオンが湿潤環境下においてめっき皮膜と反応し、腐食環境によってはめっき素地の腐食を促進し、変色やシミ状錆発生の要因となる。
【００２５】
また、前記成分（イ）としては、耐食性の優れた複合酸化物を得ることができるため、リン酸アンモニウム塩を使用することも有効である。リン酸アンモニウム塩としては、第一リン酸アンモニウム、第二リン酸アンモニウムなどの１種又は２種以上を用いることが好ましい。
【００２６】
前記成分（ロ）である酸化物微粒子としては、酸化ケイ素（ＳｉＯ_２微粒子）が最も好ましい。この酸化ケイ素は酸性水溶液中で安定な水分散性のＳｉＯ_２微粒子であればよく、市販のシリカゾルや水分散性のケイ酸オリゴマーなどを用いることができる。但し、ヘキサフルオロケイ酸などのフッ化物は腐食性が強く、人体への影響も大きいため、作業環境への影響などの観点から使用しないことが望ましい。酸化物微粒子としては、上記の酸化ケイ素のほかに、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のコロイド溶液、微粉末などを用いることもできる。
【００２７】
処理液中での、酸化物微粒子の添加量（酸化ケイ素の場合はＳｉＯ_２量としての添加量）は０．００１〜３．０モル／Ｌ、好ましくは０．０５〜１．０モル／Ｌ、さらに好ましくは０．１〜０．５モル／Ｌとする。酸化物微粒子の添加量が０．００１モル／Ｌ未満では添加による効果が十分でなく、耐食性が劣る。一方、添加量が３．０モル／Ｌを超えると皮膜の耐水性が悪くなり、結果的に耐食性も劣化する。
【００２８】
前記成分（ハ）であるＭｇ、Ｃａ、Ｓｒ、Ｂａ、Ｍｎ、Ａｌ、Ｆｅの各金属イオン、前記金属のうちの少なくとも１種を含む水溶性イオン、前記金属のうちの少なくとも１種を含む化合物、前記金属のうちの少なくとも１種を含む複合化合物の中から選ばれる１種以上を処理液中に導入するには、前記金属のリン酸塩、硫酸塩、硝酸塩、塩化物などの１種又は２種以上を処理液中に添加すればよい。
【００２９】
処理液中での上記添加成分（ハ）の添加量は、金属量換算の合計で０．００１〜３．０モル／Ｌ、好ましくは０．０１〜０．５モル／Ｌとする。これらの合計の添加量が０．００１モル／Ｌ未満では添加による効果が十分に得られず、一方、添加量が３．０モル／Ｌを超えると、逆にこれらの成分が皮膜のネットワークを阻害するようになり、緻密な皮膜ができにくくなる。また、金属成分が皮膜から溶出しやすくなり、環境によっては外観が変色するなどの欠陥を生じる。
【００３０】
また、上記添加成分（ハ）において、Ｍｇ、Ｍｎが顕著に耐食性を向上させる。Ｍｇ成分の処理液中での存在形態はＭｇを含む化合物や複合酸化物でもよいが、特に優れた耐食性を得るためには金属イオン又はＭｇが含まれる水溶性イオンの形態が特に好ましい。
【００３１】
なお、添加成分（ハ）のイオンを金属塩として供給するために、塩素イオン、硝酸イオン、硫酸イオン、酢酸イオン、ホウ酸イオンなどのアニオンが処理液中に添加されてもよい。
【００３２】
上記添加成分（ハ）を含む処理液は、酸性水溶液である点が重要である。すなわち、処理液を酸性とすることにより亜鉛などのめっき成分が溶解しやすくなるため、化成処理皮膜とめっき界面に亜鉛などのめっき成分を含むリン酸化合物層が形成され、これにより両者の界面結合が強化される結果、耐食性に優れた皮膜になると推定される。
【００３３】
処理液（水溶液）のｐＨは０．５〜５、好ましくは２〜４とすることが適当である。処理液がｐＨ０．５未満では処理液の反応性が高くなり過ぎるため皮膜に微細な欠陥部が形成され、耐食性が低下する。一方、処理液がｐＨ５を超えると処理液の反応性が低くなり、めっき皮膜と複合酸化物皮膜との界面の結合が不十分となり、この場合も耐食性が低下する。
【００３４】
本発明では、ベースとなるめっき鋼板に前記成分（イ）を含有する処理液、または成分（イ）、（ロ）及び（ハ）を含有する処理液を塗布し、しかる後、加熱乾燥して、めっき鋼板表面に第１層皮膜（下層）として、
（ａ）リン酸及び／又はリン酸化合物、
または、さらに、
（ｂ）酸化物粒子と、
（ｃ）Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｍｎ、Ａｌ、Ｆｅの中から選ばれる１種又は２種以上の金属（但し、化合物及び／又は複合化合物として含まれる場合を含む）と、を含有し、膜厚が０．００５〜４μｍのリン酸含有皮膜を形成する。
【００３５】
下層皮膜の膜厚を０．００５〜４μｍに限定したのは、膜厚が０．００５μｍ未満では耐食性性が低下し、４μｍを超えると溶性性などの導電性が低下するためである。膜厚は０．００５〜３μｍが好ましく、０．０１〜２μがさらに好ましい。
【００３６】
なお、皮膜中でのリン酸、リン酸化合物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、リン酸化合物のイオン性、溶解度についても特別な制約はない。耐食性および溶接性などの観点から上記成分（ａ）の好ましい付着量はＰ_２Ｏ_５量換算で０．０１〜３０００ｍｇ／ｍ^２、より好ましくは０．１〜１０００ｍｇ／ｍ^２、さらに好ましくは１〜５００ｍｇ／ｍ^２である。
【００３７】
耐食性および溶接性の観点から上記成分（ｂ）の好ましい付着量は０．０１〜３０００ｍｇ／ｍ^２、より好ましくは０．１〜１０００ｍｇ／ｍ^２、さらに好ましくは１〜５００ｍｇ／ｍ^２である。
【００３８】
上記成分（ｃ）である特定の金属成分（Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｍｎ、Ａｌ、Ｆｅ）が皮膜中で存在する形態は特に限定されず、金属として、あるいは酸化物、水酸化物、水和酸化物、リン酸化合物、配位化合物などのイオン性、溶解度などについても特に限定されない。
【００３９】
耐食性および皮膜外観の低下防止の観点から上記成分（ｃ）の好ましい付着量は金属量換算で０．０１〜１０００ｍｇ／ｍ^２、より好ましくは０．１〜５００ｍｇ／ｍ^２、さらに好ましくは１〜１００ｍｇ／ｍ^２ある。
【００４０】
本発明では、前記下層皮膜の上層に、膜厚が０．１〜５μｍの有機皮膜を形成させる。上層の膜厚を０．１〜５μｍに限定したのは、０．１μｍ未満では耐食性が不十分になり、５μｍを超えると、導電性、加工性が低下するためである。
【００４１】
下層皮膜を形成する処理液として、前記成分（イ）、（ロ）及び（ハ）を含有する処理液を用い、前記のようにして製造された有機複合被覆鋼板は、従来のクロメート処理鋼板に代替可能な優れた特性を有している。しかし、前記のようにして有機複合被覆鋼板を製造する際に、下層皮膜を形成させる工程において、処理液を塗布することに起因する外観むらが発生しやすいという問題のあることが明らかになった。
【００４２】
そこで、本発明者らは、下層皮膜を形成する処理液の処理条件と外観むらの発生状況について詳細に調査した。その結果、下層皮膜を形成するときに塗布する処理液の温度及び／又は処理液を塗布する直前の鋼板温度を本発明で規定する範囲に低下することで、外観むらの発生を防止できることが明らかになった。なお、前記処理液は、亜鉛めっき鋼板などのめっき鋼板との反応性が低い塗布型処理液であるので、所要の塗膜厚を確保する観点から処理液濃度の管理の必要性が認識されていたが、その他の製造条件についてはこれまで厳密な管理は必要とされていなかった。
【００４３】
以下に、本発明における鋼板温度、処理液温度の限定理由について説明する。
表１中のＮｏ．Ｂの成分組成の処理液（ｐＨ：２．７、温度：２５℃）を亜鉛めっき鋼板表面に塗布し、しかる後、加熱乾燥して、亜鉛めっき鋼板の表面に酸化物を含むリン酸含有皮膜を形成する際に、前記処理液を塗布する直前の鋼板温度を種々変え、該酸化物を含むリン酸含有皮膜皮膜形成後の鋼板表面の外観むらの発生状況を調査した。外観むらは、次のように評価した。
○：外観むらが認めらないもの。
△：軽度の外観むらが認められるもの。
×：著しい外観むらが認められるもの。
【００４４】
調査結果を図１に示す。鋼板温度を５０℃未満にすると、鋼板表面の外観むらの発生を防止する効果が認められる。５０℃未満では、鋼板温度の低下に伴い、外観むらの発生が軽微になる。本発明では、前記結果に基づいて、処理液を塗布する前の鋼板温度を５０℃未満に規定した。より好ましい鋼板温度は４０℃以下、さらに好ましい鋼板温度は２５℃以下である。
【００４５】
また、前述のＮｏ．Ｂの成分組成の処理液（ｐＨ：２．７）を亜鉛めっき鋼板表面に塗布して前記リン酸含有皮膜を有する鋼板を製造する際に、処理液温度を種々変え、該リン酸含有皮膜皮膜形成後の鋼板表面の外観むらの発生状況を調査した。外観むらは前記と同様に評価した。調査結果を図２に示す。処理液を塗布する直前の鋼板温度は４０℃である。
【００４６】
処理液温度を４０℃未満にすると外観むらの発生を軽減する効果が認められる。４０℃以下では、処理液温度の低下に伴い、外観むらの発生が軽微になる。本発明では、前記結果に基づいて、処理液温度を２５℃以下に規定した。外観むらの発生を防止する観点から、塗布性に影響を与えない範囲で処理液温度は低い方が有利である。
【００４７】
処理液を塗布する直前の鋼板温度及び該処理液の温度をそれぞれ前記で規定する範囲内にすることによって外観むらの発生を防止する効果をさらに向上できる。
【００４８】
前記処理液をめっき鋼板表面に塗布する際に、処理液温度、塗布する鋼板温度を前記で規定した範囲に低下することによって、外観むらを防止できる理由は明らかではないが、次のように推測される。すなわち、処理されるめっき皮膜の表面性状は、必ずしも均一とはいえず、部分的に活性な部分と不活性な部分が混在する場合がある。このような鋼板にリン酸及び／又はリン酸化合物を含有する処理液処理液を塗布すると、処理液温度や鋼板温度が高い場合に、処理液に含まれるリン酸及び／又はリン酸化合物が、めっき鋼板表面の活性な部分で亜鉛と僅かに反応し、外観むらになると推測される。処理液温度や鋼板温度を低下すると、表面の活性な部分でリン酸及び／又はリン酸化合物と亜鉛との反応が抑制されることで外観むらの発生が防止されるものと推測される。
【００４９】
なお、前記有機複合被覆鋼板を製造するにあたり、必要に応じて、下層を形成するための処理液を塗布する前に、予めめっき皮膜表面にアルカリ脱脂、溶剤脱脂、表面調整処理（アルカリ性の表面調整処理、酸性の表面調整処理）などの処理を施しておいてもよい。
【００５０】
【実施例】
以下、本発明の実施例について説明する。図３は本実施例において下層皮膜の形成に使用したロール塗布装置の要部設備の配置を示す概略図である。本装置を用いて下層皮膜形成のための処理液１は循環槽７と塗料パン２間をポンプ８で循環し、ピックアップロール３で塗料パン２内の処理液１を汲み上げ、汲み上げた処理液１をアプリケータロール４に転写し、さらにバックアップロール５に巻掛けられて走行する鋼板６に転写して塗布する。塗布後図示されていない加熱炉で焼き付け処理され、下層皮膜を形成する。塗布前の鋼板温度は温度計９で測定し、処理液温度は温度計１０で測定する。１１は鋼板の加熱・冷却装置、１２は処理液の加熱・冷却装置、１３は前記加熱・冷却装置１１、１２の温度を制御する制御装置である。
【００５１】
図３に示した塗布装置を用いて、板厚１．０ｍｍ、めっき付着量２０／２０ｇ／ｍ^２の電気亜鉛めっき鋼板に、表１に記載の成分組成の処理液を乾燥膜厚で０．２〜０．６μｍになるように塗布し、しかる後に焼き付け処理を行い、下層のリン酸含有皮膜を形成し、さらに図示されていないロール塗布装置で有機樹脂を含む処理液を塗布し、加熱乾燥して厚さ１．０μｍの有機皮膜を形成した。前記で得た有機複合被覆鋼板の外観むらを以下のように評価した。
（処理むらの評価基準）
○：外観むらが認めらないもの
△：軽度の外観むらが認められるもの
×：著しい外観むらが認められるもの
製造条件と外観むらの評価結果を表２に示す。
【００５２】
【表１】

【００５３】
【表２】

【００５４】
リン酸及び／又はリン酸化合物を含有する処理液を塗布する直前の鋼板温度が本発明範囲内のものは、前記範囲を外れるものに比べて外観むらが少ない。また、塗布するリン酸及び／又はリン酸化合物を含有する処理液の温度が本発明範囲内ののもは、前記範囲を外れるものに比べて外観むらが少ない。
【００５５】
リン酸及び／又はリン酸化合物を含有する処理液を塗布する直前の鋼板温度及び塗布する処理液の温度が本発明範囲内のものは、外観むらが一層軽微である。
【００５６】
【発明の効果】
本発明によれば、下層のリン酸含有皮膜の形成に起源する外観むらの発生を防止でき、表面外観に優れた有機複合被覆鋼板を製造できる。
【図面の簡単な説明】
【図１】鋼板温度と鋼板表面の外観むらの発生状況の関係を示す図である
【図２】塗液温度と鋼板表面の外観むらの発生状況の関係を示す図である
【図３】実施例において、下層皮膜を形成する処理液の塗布に使用したロール塗布装置の要部設備の配置を示す概略図である。
【符号の説明】
１処理液
２塗料パン
３ピックアップロール
４アプリケータロール
５バックアップロール
６鋼板
７循環槽
８ポンプ
９、１０温度計
１１、１２加熱・冷却装置
１３制御装置[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing an organic composite coated steel sheet in which an organic composite coating comprising an oxide-containing phosphoric acid and / or phosphate compound film as a lower layer and a resin film as an upper layer is formed. More specifically, an organic composite coated steel sheet in which an organic composite coating composed of a phosphoric acid and / or a phosphoric acid compound film containing an oxide in the lower layer, and a resin film in the upper layer is formed without uneven appearance originating in the lower layer. And a method for producing the same.
[0002]
[Prior art]
BACKGROUND ART Chromate treatment of galvanized steel sheets is widely used as an inexpensive rust prevention method for suppressing white rust of zinc. On the other hand, since the chromate treatment liquid contains hexavalent chromium, the use of wastewater treatment with a completely closed system during chromate treatment and the development of a coating-type chromate treatment technology that does not require a water washing process have been conventionally performed as environmental measures. ing. Regarding hexavalent chromium, which is contained in a trace amount of chromate film, development of organic composite coated steel plate that prevents elution of chromium and investigation of insolubility of the coating type chromate film have been conducted.
[0003]
On the other hand, chromium-free chemical conversion treated steel sheets that do not use hexavalent chromium have been developed from the viewpoint of environmental measures. For example, the following methods have been proposed.
(1) A method using tannic acid (for example, Patent Document 1)
(2) A method using a thermosetting paint in which an epoxy resin, an amino resin and tannic acid are mixed (for example, Patent Document 2)
(3) A method using a mixed composition of an aqueous resin and a polyhydric phenol carboxylic acid (for example, Patent Document 3)
(4) Surface treatment method for applying an aqueous solution of a hydrazine derivative to the surface of a tin or zinc iron plate (for example, Patent Document 4)
(5) A method using a surface treatment composition comprising an organic resin containing a hydroxyl group-containing monomer as a copolymerization component and a phosphoric acid compound of phosphoric acid and metal (for example, Patent Document 5)
(6) A method of forming an organic composite coating composed of a phosphoric acid and / or phosphate compound film containing an oxide in the lower layer and a resin film on the upper layer (for example, Patent Documents 6 and 7)
The prior art document information is described below.
[0004]
[Patent Document 1]
JP-A-51-71233 [0005]
[Patent Document 2]
JP-A-63-90581
[Patent Document 3]
JP-A-8-325760
[Patent Document 4]
JP-B-56-10386 [0008]
[Patent Document 5]
Japanese Patent Application Laid-Open No. Hei 9-208885
[Patent Document 6]
JP 2001-11645 A
[Patent Document 7]
JP 2001-11656 A
[Problems to be solved by the invention]
In the above, the organic composite coated steel sheet for forming an organic composite coating composed of a phosphoric acid and / or phosphate compound film containing an oxide in the lower layer and a resin film on the lower layer is a conventional chromate-treated steel sheet. It has characteristics that can be sufficiently substituted for. However, there is a problem that it is difficult to obtain a stable and uniform surface appearance in the step of forming a phosphoric acid and / or phosphate compound film containing an oxide.
[0012]
The present invention, in view of the above circumstances, in producing an organic composite coated steel sheet by forming an organic composite coating comprising a phosphoric acid and / or a phosphate compound film containing an oxide in the lower layer and a resin film in the upper layer, An object of the present invention is to provide a method for producing an organic composite-coated steel sheet having an excellent surface appearance free from unevenness of appearance originating in a lower layer.
[0013]
[Means for Solving the Problems]
The present inventors have found that in the above-described method for producing an organic composite coated steel sheet in which an organic composite coating composed of a phosphoric acid and / or phosphate compound film containing an oxide as a lower layer and a resin film as an upper layer is formed. By examining the method of obtaining a uniform surface appearance, by limiting the processing conditions when forming the lower layer, specifically, the steel sheet temperature and / or processing solution temperature when forming the lower layer to a specific range, It has been found that a good surface appearance can be stably obtained without causing unevenness in appearance. The present invention has been made based on this finding.
[0014]
Means of the present invention for solving the above problems are as follows.
[0015]
(1) A treatment solution containing phosphoric acid and / or a phosphoric acid compound is applied to a zinc-based plated steel sheet or an aluminum-based plated steel sheet having a temperature of less than 50 ° C., and then dried and heated to obtain a film thickness of 0.005 to 0.005. A method for producing an organic composite coated steel sheet, comprising: forming a phosphoric acid-containing coating of 4 μm, and forming an organic coating of 0.1 to 5 μm thereon.
[0016]
(2) A treatment solution containing phosphoric acid and / or a phosphoric acid compound having a temperature of 25 ° C. or lower is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and then dried and heated to a thickness of 0.005. A method for producing an organic composite coated steel sheet, comprising: forming a phosphoric acid-containing coating having a thickness of 4 to 4 m, and forming an organic coating having a thickness of 0.1 to 5 m on the coating.
[0017]
(3) A treatment liquid containing phosphoric acid and / or a phosphoric acid compound having a temperature of 25 ° C. or less is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet having a temperature of less than 50 ° C., and then dried and heated, A method for producing an organic composite coated steel sheet, comprising: forming a phosphoric acid-containing film having a thickness of 0.005 to 4 µm, and forming an organic film having a thickness of 0.1 to 5 µm thereon.
[0018]
(4) The treatment liquid containing phosphoric acid and / or a phosphoric acid compound further includes oxide fine particles, and at least one of each of metal ions of Mg, Ca, Sr, Ba, Mn, Al, and Fe, (1) to (1) to containing at least one selected from water-soluble ions containing species, compounds containing at least one of the aforementioned metals, and composite compounds containing at least one of the aforementioned metals. (3) The method for producing an organic composite coated steel sheet according to any one of (3).
[0019]
(5) It contains phosphoric acid and / or a phosphoric acid compound, and further contains oxide fine particles, and metal ions of Mg, Ca, Sr, Ba, Mn, Al, and Fe, and at least one of the above metals. The treatment liquid containing at least one selected from a water-soluble ion, a compound containing at least one of the metals, and a composite compound containing at least one of the metals, contains phosphoric acid and / or phosphoric acid The compound contains 0.001 to 6.0 mol / L in terms of P ₂ O ₅ , and further contains 0.001 to 3.0 mol / L of oxide fine particles, Mg, Ca, Sr, Ba, Mn, Al, 1 selected from metal ions of Fe, water-soluble ions containing at least one of the above metals, compounds containing at least one of the above metals, and composite compounds containing at least one of the above metals; More than species, before (4) The method for producing an organic composite coated steel sheet according to (4), which is an acidic aqueous solution having a pH of 0.5 to 5 and containing a total of 0.001 to 3.0 mol / L in terms of a metal amount of the metal.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, the zinc-coated steel sheet serving as the base of the organic-coated steel sheet includes a zinc-coated steel sheet, a Zn-Ni alloy-coated steel sheet, a Zn-Fe alloy-coated steel sheet (electroplated steel sheet and galvannealed steel sheet), Zn-coated steel sheet. An Al alloy plated steel sheet (for example, a Zn-5% Al alloy plated steel sheet, a Zn-55% Al alloy plated steel sheet) or the like can be used. In addition, as the aluminum-based plated steel sheet serving as the base of the organic-coated steel sheet of the present invention, an aluminum-plated steel sheet, an Al—Si alloy-plated steel sheet, or the like can be used.
[0021]
In the present invention, a treatment solution containing phosphoric acid and / or a phosphoric acid compound is applied to the zinc-based plated steel sheet or the aluminum-based plated steel sheet as a base, and then dried and heated to form a lower phosphoric acid-containing coating. Is formed, and an organic film is formed thereon.
[0022]
The treatment solution containing phosphoric acid and / or a phosphoric acid compound used for forming the lower phosphate-containing film contains (a) phosphoric acid and / or a phosphoric acid compound, or further contains (b) oxide fine particles. (C) Mg, Ca, Sr, Ba, Mn, Al, Fe metal ions, water-soluble ions containing at least one of the metals, compounds containing at least one of the metals, the metal And at least one selected from composite compounds containing at least one of the above.
[0023]
Examples of the phosphoric acid and / or the phosphoric acid compound as the component (a) include orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid such as tripolyphosphoric acid, metaphosphoric acid, and inorganic salts thereof (for example, aluminum monophosphate). Phosphorus-containing compounds such as phosphorous acid, phosphite, hypophosphorous acid, and hypophosphite are present as anions generated when dissolved in an aqueous solution or as complex ions with metal cations. The amount of the phosphoric acid component in the present invention includes all the forms existing as the free acid and the like, and the total of all these forms existing in the acidic aqueous solution is defined as P ₂ O ₅ conversion.
[0024]
The addition amount of phosphoric acid and / or phosphoric acid compound in the processing solution from 0.001 to 6.0 mol / L in terms _of _P 2 _{O 5,} preferably from 0.02 to 1.0 mol / L, more preferably 0.1 to 0.8 mol / L. If the amount of phosphoric acid and / or phosphoric acid compound is less than 0.001 mol / L, the effect of the addition is not sufficient, and the corrosion resistance is poor. On the other hand, if the added amount exceeds 6.0 mol / L, excess phosphate ions react with the plating film in a humid environment, and depending on the corrosive environment, accelerate the corrosion of the plating base material and cause discoloration or spot-like rust. It becomes.
[0025]
In addition, as the component (a), a composite oxide having excellent corrosion resistance can be obtained, and thus it is effective to use an ammonium phosphate salt. As the ammonium phosphate salt, it is preferable to use one or more kinds of ammonium phosphate monobasic, ammonium phosphate dibasic and the like.
[0026]
As the oxide fine particles as the component (b), silicon oxide (SiO ₂ fine particles) is most preferable. The silicon oxide may be any water-dispersible SiO ₂ fine particles that are stable in an acidic aqueous solution, and commercially available silica sol or water-dispersible silicate oligomer can be used. However, since fluorides such as hexafluorosilicic acid are highly corrosive and greatly affect the human body, it is desirable not to use them from the viewpoint of affecting the working environment. As the oxide fine particles, in addition to the above silicon oxide, a colloid solution of aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, antimony oxide, or the like, fine powder, or the like can also be used.
[0027]
The amount of the oxide fine particles (in the case of silicon oxide, the amount of SiO ₂ added) in the treatment liquid is 0.001 to 3.0 mol / L, preferably 0.05 to 1.0 mol / L. And more preferably 0.1 to 0.5 mol / L. If the amount of the oxide fine particles is less than 0.001 mol / L, the effect of the addition is not sufficient, and the corrosion resistance is poor. On the other hand, when the addition amount exceeds 3.0 mol / L, the water resistance of the film becomes poor, and as a result, the corrosion resistance also deteriorates.
[0028]
Metal ions of Mg, Ca, Sr, Ba, Mn, Al, and Fe, water-soluble ions containing at least one of the above metals, and compounds containing at least one of the above metals In order to introduce one or more selected from a composite compound containing at least one of the metals into the treatment solution, one or more of phosphates, sulfates, nitrates, and chlorides of the metals or Two or more kinds may be added to the processing solution.
[0029]
The amount of the additional component (c) in the treatment liquid is 0.001 to 3.0 mol / L, preferably 0.01 to 0.5 mol / L in terms of the total amount of metal. If the total amount of these components is less than 0.001 mol / L, the effect of the addition will not be sufficiently obtained. On the other hand, if the total amount exceeds 3.0 mol / L, these components will adversely affect the film network. Hinders the formation of a dense film. Further, the metal component is easily eluted from the film, and depending on the environment, a defect such as discoloration of the appearance occurs.
[0030]
In addition, in the additive component (C), Mg and Mn significantly improve corrosion resistance. The form in which the Mg component is present in the treatment liquid may be a compound containing Mg or a composite oxide, but in order to obtain particularly excellent corrosion resistance, a form of a metal ion or a water-soluble ion containing Mg is particularly preferable.
[0031]
In order to supply the ions of the additive component (c) as a metal salt, anions such as chloride, nitrate, sulfate, acetate, and borate may be added to the treatment liquid.
[0032]
It is important that the treatment liquid containing the additive component (c) is an acidic aqueous solution. That is, since the plating component such as zinc is easily dissolved by making the treatment solution acidic, a phosphate compound layer containing the plating component such as zinc is formed at the interface between the chemical conversion treatment film and the plating, thereby forming an interface between the two. As a result, it is estimated that a film having excellent corrosion resistance results.
[0033]
It is appropriate that the pH of the treatment liquid (aqueous solution) is 0.5 to 5, preferably 2 to 4. If the pH of the treatment liquid is less than 0.5, the reactivity of the treatment liquid becomes too high, so that fine defects are formed in the film, and the corrosion resistance is reduced. On the other hand, if the pH of the treatment liquid exceeds 5, the reactivity of the treatment liquid becomes low, the bonding at the interface between the plating film and the composite oxide film becomes insufficient, and the corrosion resistance also decreases in this case.
[0034]
In the present invention, a treatment liquid containing the component (a) or a treatment liquid containing the components (a), (b) and (c) is applied to a base plated steel sheet, and then heated and dried. , As the first layer film (lower layer) on the surface of the plated steel sheet,
(A) phosphoric acid and / or a phosphoric acid compound,
Or, moreover,
(B) oxide particles;
(C) one or more metals selected from Mg, Ca, Sr, Ba, Mn, Al, and Fe (including the case where they are included as a compound and / or a composite compound). To form a phosphoric acid-containing film having a thickness of 0.005 to 4 μm.
[0035]
The reason why the thickness of the lower layer film is limited to 0.005 to 4 μm is that if the film thickness is less than 0.005 μm, the corrosion resistance decreases, and if it exceeds 4 μm, the conductivity such as solubility decreases. The thickness is preferably 0.005 to 3 μm, more preferably 0.01 to 2 μm.
[0036]
The form of the phosphoric acid or the phosphoric acid compound in the film is not particularly limited, and may be crystalline or non-crystalline. Further, there is no particular restriction on the ionicity and solubility of phosphoric acid and the phosphoric acid compound in the film. Preferred coating weight 0.01~3000mg / ^{m 2} with _P 2 _{O 5} amount conversion from the viewpoint of the above components, such as corrosion resistance and weldability (a), more preferably 0.1 to 1000 mg / ^{m 2,} more preferably 1 ５００500 mg / m ² .
[0037]
Preferred coating weight of the corrosion resistance and weldability viewpoint from the component (b) 0.01~3000mg / ^{m 2,} more preferably 0.1 to 1000 mg / ^{m 2,} more preferably from 1-500 mg / ^{m 2.}
[0038]
The form in which the specific metal component (Mg, Ca, Sr, Ba, Mn, Al, Fe) as the component (c) is present in the film is not particularly limited, and may be a metal or an oxide, a hydroxide, The ionicity, solubility, and the like of the hydrated oxide, the phosphate compound, the coordination compound, and the like are not particularly limited.
[0039]
From the viewpoints of corrosion resistance and prevention of deterioration of the film appearance, the preferable amount of the component (c) to be applied is 0.01 to 1000 mg / m ² , more preferably 0.1 to 500 mg / m ² , further preferably 1 to 1 in terms of metal amount. 100 mg / m ² .
[0040]
In the present invention, an organic film having a thickness of 0.1 to 5 μm is formed on the lower film. The reason why the thickness of the upper layer is limited to 0.1 to 5 μm is that if it is less than 0.1 μm, the corrosion resistance becomes insufficient, and if it exceeds 5 μm, the conductivity and workability decrease.
[0041]
As the treatment liquid for forming the lower layer film, the treatment liquid containing the components (a), (b) and (c) is used, and the organic composite coated steel sheet produced as described above is replaced with a conventional chromate-treated steel sheet. It has excellent properties that can be replaced. However, when manufacturing the organic composite coated steel sheet as described above, it has been revealed that in the step of forming the lower layer film, there is a problem that unevenness in appearance due to application of the treatment liquid easily occurs. .
[0042]
Then, the present inventors investigated in detail the processing conditions of the processing solution for forming the lower layer film and the appearance of uneven appearance. As a result, it is apparent that unevenness in appearance can be prevented by lowering the temperature of the treatment liquid to be applied when forming the lower layer coating and / or the steel sheet temperature immediately before the application of the treatment liquid to the range specified in the present invention. Became. Since the treatment liquid is a coating treatment liquid having low reactivity with a galvanized steel sheet such as a galvanized steel sheet, the necessity of managing the concentration of the treatment liquid from the viewpoint of securing a required coating film thickness has been recognized. However, other production conditions have not been required to be strictly controlled.
[0043]
Hereinafter, the reasons for limiting the steel sheet temperature and the treatment liquid temperature in the present invention will be described.
No. 1 in Table 1. A treatment liquid (pH: 2.7, temperature: 25 ° C.) having a component composition of B is applied to the surface of a galvanized steel sheet, and then dried by heating to form a phosphoric acid-containing film containing an oxide on the surface of the galvanized steel sheet. In forming the steel sheet, the temperature of the steel sheet immediately before application of the treatment liquid was variously changed, and the occurrence of uneven appearance of the steel sheet surface after the formation of the phosphoric acid-containing film containing the oxide was investigated. The appearance unevenness was evaluated as follows.
：: No uneven appearance is observed.
Δ: Mild appearance unevenness was observed.
X: A thing with remarkable appearance unevenness is recognized.
[0044]
FIG. 1 shows the results of the investigation. When the steel sheet temperature is lower than 50 ° C., the effect of preventing the appearance unevenness of the steel sheet surface from occurring is recognized. If the temperature is lower than 50 ° C., the occurrence of unevenness in appearance becomes small as the temperature of the steel sheet decreases. In the present invention, based on the above results, the temperature of the steel sheet before applying the treatment liquid is specified to be less than 50 ° C. A more preferred steel sheet temperature is 40 ° C. or less, and a still more preferred steel sheet temperature is 25 ° C. or less.
[0045]
In addition, the aforementioned No. When producing a steel sheet having the phosphoric acid-containing film by applying a treatment liquid (pH: 2.7) having the component composition of B to the surface of the galvanized steel sheet, the treatment liquid temperature is variously changed, and the phosphoric acid-containing film film is formed. The state of appearance unevenness of the steel sheet surface after the formation was investigated. Appearance unevenness was evaluated in the same manner as described above. FIG. 2 shows the results of the investigation. The temperature of the steel sheet immediately before the application of the treatment liquid is 40 ° C.
[0046]
When the temperature of the treatment liquid is lower than 40 ° C., the effect of reducing the appearance unevenness is recognized. When the temperature is lower than 40 ° C., the occurrence of unevenness in appearance becomes small as the temperature of the processing liquid decreases. In the present invention, based on the above results, the processing liquid temperature is specified to be 25 ° C. or less. From the viewpoint of preventing appearance unevenness, it is advantageous that the temperature of the treatment liquid is lower as long as the coatability is not affected.
[0047]
By setting the temperature of the steel sheet immediately before the application of the treatment liquid and the temperature of the treatment liquid within the ranges specified above, the effect of preventing appearance unevenness can be further improved.
[0048]
When applying the treatment liquid to the surface of the plated steel sheet, it is not clear why the appearance liquid can be prevented by lowering the treatment liquid temperature and the temperature of the steel sheet to be applied to the above-defined range, but the following is presumed. Is done. That is, the surface properties of the plating film to be treated are not necessarily uniform, and there are cases where a partially active portion and an inactive portion are mixed. When a treatment liquid containing phosphoric acid and / or a phosphoric acid compound is applied to such a steel sheet, when the treatment liquid temperature or the steel sheet temperature is high, the phosphoric acid and / or the phosphoric acid compound contained in the treatment liquid is It is presumed that the active portion of the surface of the plated steel sheet slightly reacts with zinc, resulting in uneven appearance. It is presumed that when the temperature of the treatment liquid or the temperature of the steel sheet is lowered, the reaction between the phosphoric acid and / or the phosphoric acid compound and zinc is suppressed in the active portion of the surface, thereby preventing appearance unevenness.
[0049]
In the production of the organic composite coated steel sheet, if necessary, before applying the treatment liquid for forming the lower layer, the surface of the plating film is previously subjected to alkali degreasing, solvent degreasing, surface conditioning treatment (alkaline surface conditioning). Treatment, an acidic surface conditioning treatment) or the like.
[0050]
【Example】
Hereinafter, examples of the present invention will be described. FIG. 3 is a schematic view showing the arrangement of the main equipment of the roll coating apparatus used for forming the lower layer coating in the present embodiment. Using this apparatus, the processing liquid 1 for forming the lower layer film is circulated between the circulation tank 7 and the paint pan 2 by the pump 8, the pickup roll 3 pumps up the processing liquid 1 in the paint pan 2, and the pumped processing liquid 1. Is transferred to an applicator roll 4 and further transferred and applied to a steel plate 6 which is wound around a backup roll 5 and travels. After the application, it is baked in a heating furnace (not shown) to form a lower layer film. The temperature of the steel sheet before application is measured by a thermometer 9, and the temperature of the treatment liquid is measured by a thermometer 10. Reference numeral 11 denotes a heating / cooling device for the steel sheet, 12 denotes a heating / cooling device for the treatment liquid, and 13 denotes a control device for controlling the temperatures of the heating /

cooling devices

11 and 12.
[0051]
Using a coating apparatus shown in FIG. 3, a treatment liquid having a component composition shown in Table 1 was applied to an electrogalvanized steel sheet having a plate thickness of 1.0 mm and a coating weight of 20/20 g / m ^{2 in} a dry film thickness of 0.1 mm. 2 to 0.6 μm, followed by baking treatment to form a lower phosphoric acid-containing film, and further applying a treatment liquid containing an organic resin by a roll coating device (not shown), and drying by heating. As a result, an organic film having a thickness of 1.0 μm was formed. The appearance unevenness of the organic composite coated steel sheet obtained above was evaluated as follows.
(Evaluation criteria for uneven processing)
：: No uneven appearance is observed. △: Slight uneven appearance is observed. X: Notable unevenness is observed. Table 2 shows the production conditions and evaluation results of the uneven appearance.
[0052]
[Table 1]

[0053]
[Table 2]

[0054]
Sheets having a steel sheet temperature within the range of the present invention immediately before the application of the treatment solution containing phosphoric acid and / or a phosphoric acid compound have less unevenness in appearance than those outside the above range. In addition, when the temperature of the treatment solution containing phosphoric acid and / or a phosphoric acid compound to be applied is within the range of the present invention, the appearance unevenness is less than those outside the above range.
[0055]
When the temperature of the steel sheet immediately before the application of the treatment liquid containing phosphoric acid and / or the phosphoric acid compound and the temperature of the treatment liquid to be applied fall within the range of the present invention, the unevenness in appearance is further reduced.
[0056]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the appearance unevenness originating in formation of a lower phosphoric acid containing film can be prevented, and the organic composite coated steel sheet excellent in surface appearance can be manufactured.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between the temperature of a steel sheet and the appearance of uneven appearance on the surface of the steel sheet; FIG. 2 is a diagram showing the relationship between the coating liquid temperature and the appearance of uneven appearance on the surface of the steel sheet; FIG. 3 is a schematic view showing an arrangement of main equipment of a roll coating apparatus used for applying a treatment liquid for forming a lower layer film in an example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Processing liquid 2 Paint pan 3 Pickup roll 4 Applicator roll 5 Backup roll 6 Steel plate 7 Circulation tank 8 Pump 9, 10

Thermometer

11, 12 Heating / cooling device 13 Control device

Claims

A treatment solution containing phosphoric acid and / or a phosphoric acid compound is applied to a zinc-based plated steel sheet or an aluminum-based plated steel sheet having a temperature of less than 50 ° C., and then dried and heated to obtain a phosphorous film having a thickness of 0.005 to 4 μm. A method for producing an organic composite coated steel sheet, comprising: forming an acid-containing film, and forming an organic film having a thickness of 0.1 to 5 μm thereon.

A treatment solution containing phosphoric acid and / or a phosphoric acid compound at a temperature of 25 ° C. or lower is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet, and then dried and heated to a thickness of 0.005 to 4 μm. A method for producing an organic composite coated steel sheet, comprising: forming a phosphoric acid-containing film, and forming an organic film having a thickness of 0.1 to 5 μm thereon.

A treatment solution containing phosphoric acid and / or a phosphoric acid compound at a temperature of 25 ° C. or less is applied to the surface of a zinc-based plated steel sheet or an aluminum-based plated steel sheet having a temperature of less than 50 ° C., and then dried and heated to obtain a film thickness. A method for producing an organic composite coated steel sheet, comprising: forming a phosphoric acid-containing film having a thickness of 0.005 to 4 μm, and forming an organic film having a thickness of 0.1 to 5 μm thereon.

The treatment solution containing phosphoric acid and / or a phosphoric acid compound further contains oxide fine particles, and metal ions of Mg, Ca, Sr, Ba, Mn, Al, and Fe, and at least one of the above metals. 2. A treatment liquid containing at least one selected from water-soluble ions, a compound containing at least one of the metals, and a composite compound containing at least one of the metals. 4. The method for producing an organic composite coated steel sheet according to any one of Items 3 to 3.

Water-soluble ions containing phosphoric acid and / or a phosphoric acid compound, and further containing oxide fine particles, and metal ions of Mg, Ca, Sr, Ba, Mn, Al, and Fe, and at least one of the above metals A treatment solution containing at least one compound selected from a compound containing at least one of the above-mentioned metals and a composite compound containing at least one of the above-mentioned metals contains phosphoric acid and / or a phosphate compound. _It contains 0.001-6.0 mol / L in terms of ₂ O ₅ , and further contains 0.001-3.0 mol / L of oxide fine particles, each of Mg, Ca, Sr, Ba, Mn, Al, and Fe. A metal ion, a water-soluble ion containing at least one of the above metals, a compound containing at least one of the above metals, and at least one selected from a composite compound containing at least one of the above metals. , The metal Method for producing an organic composite coated steel sheet according to claim 4, characterized in that the total 0.001 to 3.0 mol / L aqueous acidic solution pH0.5~5 containing metal amount conversion.