JP3962123B2 - Organic surface treatment metal plate and organic metal surface treatment liquid - Google Patents
Organic surface treatment metal plate and organic metal surface treatment liquid Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、耐食性に優れ、且つ６価クロムを全く含まない被覆層を有する表面処理金属板及びその処理液に関するものである。
【０００２】
【従来の技術】
従来、自動車、家電製品、建材等の用途に用いられる冷延鋼板、亜鉛めっき鋼板および亜鉛系合金めっき鋼板、アルミニウムめっき鋼板などは、防錆性を付与するため等に、それらの表面にクロメート皮膜を被覆することが一般に行なわれている。このクロメート処理としては、電解型クロメートや塗布型クロメートがある。電解型クロメートは、例えばクロム酸を主成分とし、他に硫酸、りん酸、硼酸およびハロゲンなどの各種陰イオンを添加した浴を用いて、金属板を陰極電解処理することにより行なわれてきた。また、塗布型クロメートは、クロメート処理金属板からのクロムの溶出の問題があり、あらかじめ６価クロムの一部を３価に還元した溶液や６価クロムと３価クロム比を特定化した溶液に無機コロイドや無機アニオンを添加して処理液とし、金属板をその中に浸漬したり、処理液を金属板にスプレーしたりすることにより行なわれてきた。
【０００３】
クロメート皮膜の内、電解によって形成されたクロメート皮膜は６価クロムの溶出性は少ないものの防食性は十分とは言えず、特に加工時などの皮膜損傷が大きい場合、その耐食性は低下する。一方、塗布型クロメート皮膜により被覆された金属板の耐食性は高く、特に加工部耐食性に優れているが、クロメート皮膜からの６価クロムの溶出が大きく問題となる。有機重合体を被覆すれば６価クロムの溶出はかなり抑制されるものの十分ではない。また、特開平５ー２３０６６６号公報に開示されているような一般に樹脂クロメートと呼ばれる方法では６価クロムの溶出抑制に改善は見られるものの、微量の溶出は避けられない。
このように６価クロムの溶出を完全に抑えるためには、６価クロムを全く使用せず従来の６価クロムを含有するクロメート皮膜と同等の機能を有する防錆性皮膜の開発が必要となる。
【０００４】
【発明が解決しようとする課題】
本発明は、これらの問題点を解決して、クロメート皮膜に代替できる表面処理金属板およびその処理液を提供することを目的としている。
【０００５】
【課題を解決するための手段】
現行クロメート処理に変わる汎用化成処理皮膜を６価クロムを全く含有しない系で設計し、かつ上記問題を解消するため、発明者らは鋭意研究を重ねた結果、希土類金属元素のポリりん酸化合物もしくはこれらの混合物と、これらを物理的に金属板表面に保持し、かつ金属板と密着力を有する樹脂マトリックスを主成分とする皮膜が、金属板の腐食抑制に効果的であることを見出した。
【０００６】
本発明の要旨は、
（１）希土類金属元素のポリりん酸化合物もしくはこれらの混合物と、これらを物理的に金属板表面に保持し、かつ金属板と密着力を有する樹脂マトリックスが主成分である皮膜で被覆してなることを特徴とする表面処理金属板。
（２）希土類金属元素のポリりん酸化合物もしくはこれらの混合物、及び樹脂マトリックス成分が主成分であることを特徴とする金属表面処理液。
（３）希土類金属元素がランタン、セリウム、イットリウムであることを特徴とする前記（１）記載の表面処理金属板。
（４）希土類金属元素がランタン、セリウム、イットリウムであることを特徴とする前記（２）記載の金属表面処理液である。
【０００７】
【発明の実施の形態】
希土類金属元素は、メカニズムが定かではないが防食機能を有している。本発明に使用される希土類金属元素の化合物もしくはこれらの混合物（以下、「希土類金属元素化合物」と略す）には、すべての希土類金属元素が使用でき、希土類金属の価数は、特に制限されない。取り扱いのしやすさから好ましくは、ランタノイドおよび／またはイットリウム、さらに経済的に好ましくはランタンまたはセリウム、より好ましくは酸化力を合わせ持った４価のセリウムである。セリウムはカソーディック反応の抑制にも有効であり、４価のセリウムを用いると更にその効果が増す。
【０００８】
本発明に使用される希土類金属元素のポリりん酸化合物は、希土類金属元素のポリりん酸化合物もしくはポリりん酸水素化合物またはこれらの混合物（以下、「希土類金属元素のポリりん酸化合物」と略す）であると好適である。希土類金属元素のポリりん酸化合物とは、ポリりん酸イオンと希土類金属元素との化合物を指称し、ポリりん酸水素化合物とはカチオンの一部に水素を含む化合物を指称する。これらポリりん酸化合物および/またはポリりん酸水素化合物は、ペースト状でおそらくは非結晶性（非晶質）の無機重合体を形成しているために、成膜しても加工追従性を有し、そのバリヤー効果により腐食を抑制するとともに、ポリりん酸を過剰にすることでりん酸塩皮膜型の不働態皮膜を形成し、かつ酸化物皮膜型の不働態皮膜を形成させることができるため、さらに高い防食性能を持った無機系耐食性化成処理皮膜を得ることが出来る。
【０００９】
本発明に使用される希土類金属元素のポリりん酸化合物は、長期耐食性を付与するために難水溶性のものが好ましく、希土類金属元素のポリりん酸化合物の水に対する溶解度がｐＨ６〜７で希土類金属元素換算で０．０１ｍｏｌ／ｌ以下であることが好ましい。より好ましくはｐＨ５〜８で溶解度が希土類金属元素換算で０．０１ｍｏｌ／ｌ以下であるとさらに長期間耐食性を維持できる。ｐＨ６〜７での水に対する溶解度が０．０１ｍｏｌ／ｌ超であると、雨水や結露など湿潤環境下で皮膜から容易に希土類金属元素のポリりん酸化合物が溶出するため、湿潤環境での長期耐食性能が低くなる。
【００１０】
また、加工部や傷付き部の耐食性を付与するためには、酸性域で水溶性になる希土類金属元素化合物が好ましい。具体的には、希土類金属元素のポリりん酸化合物のｐＨ３以下における溶解度が希土類金属元素換算で０．１ｍｏｌ／ｌ以上であることが好ましい。０．１ｍｏｌ／ｌ以上にする事によって、腐食発生箇所のｐＨ低下に応答して希土類金属元素のポリりん酸化合物が溶解し、加工部や傷付き部など腐食進行部分を選択的に補修する機能を付与する事ができる。０．１ｍｏｌ／ｌ未満では、厳しい加工で皮膜に損傷を受け、かつ極めて厳しい腐食環境にさらされたとき、腐食箇所への希土類金属元素のポリりん酸化合物の供給が不十分になり、耐食性が低くなる。
【００１１】
本発明に使用される希土類金属元素のポリりん酸化合物は、同一皮膜中において１種類を添加して使用することも可能であるが、希土類金属元素あるいはポリりん酸を変えた複数の希土類金属元素のポリりん酸化合物を添加して使用することもできる。複数の希土類金属元素のポリりん酸化合物を添加した方が、種々の腐食環境に幅広く対応可能になるが、実際的には製造コストや溶接性などの皮膜特性によって皮膜厚さに制限があり、皮膜に添加される希土類金属元素のポリりん酸化合物の単位面積当たりの絶対量が限定されるため、量と種類は最適化しなければならない。
【００１２】
金属板上の皮膜中に含まれる希土類金属元素のポリりん酸化合物の量としては、求められる耐食性により必要添加量が変わるため限定することは出来ないが、希土類金属換算で１ｍｇ／ｍ2以上であれば良い。１ｍｇ／ｍ2未満では、添加効果が不十分で皮膜としての耐食性向上が認められない。また、１０ｍｇ／ｍ2を超えて添加しても耐食性向上効果は飽和してしまうため、経済性を考慮すると１０ｍｇ／ｍ2で十分である。
【００１３】
希土類金属元素のポリりん酸化合物の処理液中での存在形態は、使用される溶媒やｐＨ、温度、濃度に依存するが、溶解した状態または処理液中に微細分散したコロイド状が好ましい。これら以外では、皮膜を形成したときに希土類金属元素のポリりん酸化合物の分散状態が不均一になり、希土類金属元素のポリりん酸化合物の存在量が少ないところが腐食しやすくなる。希土類金属元素のポリりん酸化合物をコロイド状に微細分散した場合の平均粒子径としては、１μｍ以下が好ましく、さらには０．５μｍ以下、特に０．２μｍ以下が好ましい。粒子径が１μｍ以上であると、処理液中や皮膜中での希土類金属元素のポリりん酸化合物の分散状態が不均一になるばかりか、加工したときに粒子を起点として皮膜が破れやすくなり耐食性が著しく悪くなる。
【００１４】
本発明に使用される樹脂マトリックス成分としては、処理液中での希土類金属元素のポリりん酸化合物の分散安定度を著しく損なうものでなく、かつ希土類金属元素のポリりん酸化合物を物理的に金属表面に保持し金属板と密着性を有する材料であれば良く、特に限定されるものではない。一般的には、アクリル系、エポキシ系、オレフィン系などの有機樹脂が例としてあげられ、形態としては、水溶性、水に分散したエマルジョン樹脂、ラテックスなどを適宜選択できる。
【００１５】
本発明の皮膜や処理液には、性能を向上させるため有機腐食抑制剤、不働態化皮膜形成助剤、分散剤や消泡剤などの界面活性剤、その他添加物を複合して使用することもできる。不働態化皮膜形成助剤としてりん酸、ポリりん酸、また、添加物として水酸化カルシウム、炭酸カルシウム、酸化カルシウム、りん酸亜鉛、りん酸カリウム、りん酸カルシウム、ケイ酸カルシウム、ケイ酸ジルコニウム、りん酸アルミニウム、りん酸ジルコニウム、ＴｉＯ2 、ＳｉＯ2 、Ａｌ2 Ｏ3 などを添加できる。本発明の皮膜を形成するための処理液は、基本的に希土類金属元素のポリりん酸化合物とマトリックス成分と溶媒から構成され、処理液の濃度やpHは特に限定されない。溶媒は水系、揮発性有機化合物の何れでも選択できる。但し、作業環境を考慮に入れると水系の方が好ましい。
【００１６】
本発明の表面処理金属板の製造方法としては、処理液を金属板表面に塗布し乾燥すれば良く、とくに限定しない。例えば、現在使用されているクロメート処理の塗布設備や塗料の塗装設備などそのまま流用でき、特別な設備を必要としない。また、刷毛塗りやバーコーターを使用して手作業で塗布し、乾燥する事によって皮膜を形成することも出来る。乾燥条件は、一概には限定することはできないが、少なくとも処理液中に含まれる溶媒を乾燥し、かつ含有する樹脂マトリックス成分が分解しない温度範囲で乾燥されれば良い。例えば、金属板表面到達温度が５０℃〜２００℃の範囲が好ましい。
【００１７】
膜厚は、用途によって変わるため限定することは出来ないが、０．０１μｍ以上が好ましい。さらに好ましくは、０．１μｍ以上である。０．０１μｍ未満では耐食性が十分ではない。しかし、膜厚が１０μｍを越えても耐食性向上効果は飽和してしまうため、経済性を考慮すると１０μｍで十分である。
この発明の対象となる金属板は特に限定されないが、例えば溶融亜鉛めっき鋼板、溶融亜鉛ー鉄合金めっき鋼板、溶融亜鉛ーアルミニウムーマグネシウム合金めっき鋼板、溶融アルミニウムーシリコン合金めっき鋼板、溶融鉛ースズ合金めっき鋼板などの溶融めっき鋼板や、電気亜鉛めっき鋼板、電気亜鉛ーニッケル合金めっき鋼板、電気亜鉛ー鉄合金めっき鋼板、電気亜鉛ークロム合金めっきなどの電気めっき鋼板などの表面処理鋼板、冷延鋼板や亜鉛、アルミニウム、マグネシウムなどの金属板などに適用できる。
【００１８】
【実施例】
希土類金属元素のポリりん酸化合物
（１）ポリりん酸／ランタン化合物（略号：ＰＰ−Ｌａ）
塩化ランタン水溶液とポリりん酸（昭和化学社製：平均分子量約３３８）をモル比Ｌａ／Ｐにして１／６の割合で十分に混合した後、２００℃で１２時間加熱した。
【００１９】
（２）ポリりん酸／セリウム（ＩＩＩ）化合物（略号：ＰＰ−Ｃｅ）
塩化セリウム水溶液とポリりん酸（昭和化学社製：平均分子量約３３８）をモル比Ｃｅ／Ｐにして１／６の割合で十分に混合した後、２００℃で１２時間加熱した。
（３）ポリりん酸／セリウム（ＩＶ）化合物（略号：ＰＰ−ＣｅＩＶ）
硝酸二アンモニウムセリウム（ＩＶ）をポリりん酸（昭和化学社製：平均分子量約３３８）中に溶解（モル比Ｃｅ／Ｐにして１／６の割合）した後、２００℃で１２時間加熱した。
【００２０】
樹脂マトリックス
（Ａ）ブロックコポリマー
ポリ（メタクリル酸、ヒドロキシエチルアクリレート、ヒドロキシエチルメタクリレート）−ポリ（スチレン、メタクリル酸メチル、メタクリル酸ブチル、アクリル酸ブチル）−ポリ（メタクリル酸、ヒドロキシエチルアクリレート、ヒドロキシエチルメタクリレート）ブロック共重合体（溶媒：テトラヒドロフラン）をリビングアニオン重合法により製造した。
（Ｂ）アクリル系エマルジョン
市販の水分散性カルボキシル基含有アクリル系エマルジョン樹脂（日本合成ゴム社製：樹脂固形分５０重量％）を使用した。
（Ｃ）ＳＢＲラテックス
市販の水分散カルボキシル基含有ＳＢＲラテックス（日本合成ゴム社製：樹脂固形分５０重量％）を使用した。
【００２１】
処理液の調製
上記した希土類金属元素のポリりん酸化合物、樹脂マトリックス、及び添加物としてオルソりん酸またはコロイダルシリカ溶液(日産化学製、ＳＴ−Ｏ）を配合して建浴した。なお、比較として樹脂マトリックス単味も建浴した。それぞれの建浴組成を表１に示した。また、建浴濃度は、希土類金属元素のポリりん酸化合物を希土類金属換算で１００ｇ／ｌ、樹脂マトリックスを固形分換算で１００ｇ／ｌ、オルソりん酸をＨ3ＰＯ4として２０ｇ／ｌ、コロイダルシリカをＳｉＯ2 換算で５ｇ／ｌの条件に統一した。
【００２２】
皮膜形成法
上記したそれぞれの処理浴を鋼板上に塗布、乾燥し皮膜形成を行った。鋼板への塗布量は、皮膜厚さにして約０．５μｍにすべて統一した。用いた鋼板はＧＩ（溶融亜鉛めっき鋼板、めっき付着量：９０ｇ／ｍ2）、ＥＧ（電気亜鉛めっき鋼板、めっき付着量：２０ｇ／ｍ2）、ＳＺ（溶融亜鉛−アルミニウム合金めっき鋼板、めっき付着量：９０ｇ／ｍ2、Ｚｎ／Ａｌ＝９５．２／４．８）、ＡＬ（溶融アルミニウム−シリコン合金めっき鋼板、めっき付着量：１２０ｇ／ｍ2、Ａｌ／Ｓｉ＝９０／１０）、ＣＲ（冷延鋼板）を用いた。尚、クロメート処理鋼板との比較を行うべく、クロメート処理液として、澱粉による部分還元クロム酸をＣｒＯ3 換算で３０ｇ／１、ＳｉＯ2 を４０ｇ／ｌ、オルソりん酸を２０ｇ／ｌ含有する処理液を建浴し、金属クロム換算で約５０ｍｇ／ｍ2 となるように鋼板上に塗布、乾燥し皮膜形成を行った。尚、塗布はバーコーターを用い、雰囲気温度２００℃で３０秒間乾燥した。
【００２３】
皮膜の性能評価法
（Ｉ）平板耐食性をサンプルに５％、３５℃の塩水を噴霧した後の錆発生率で評価した。尚、噴霧期間はＧＩ，ＥＧ，ＳＺが１０日、ＡＬが１５日で何れも白錆発生率、ＣＲが５日で赤錆発生率を測定した。
評点：◎：錆発生無し
○：錆発生率 ５％未満
△：錆発生率 ５％超、２０％未満
×：錆発生率 ２０％超
【００２４】
（ＩＩ）サンプルをエリクセン７ｍｍ加工後、５％、３５℃の塩水を噴霧した後の錆発生面積で加工部耐食性評価を行なった。なお、噴霧期間はＧＩ，ＥＧ，ＳＺが１０日間、ＡＬが１５日間で何れも白錆発生率、ＣＲが５日で赤錆発生率を測定した。
評点 ◎：錆発生率 ０％
○：錆発生率 ５％未満
△：錆発生率 ５％以上、２０％未満
×：錆発生率 ２０％以上
【００２５】
（ＩＩＩ）塗料密着性をサンプル上にメラミン−アルキド塗料を厚さ約２０μｍ塗布焼き付けし、沸騰水に３０分浸漬後の基盤目試験（１ｍｍ角碁盤を１０×１０カットしテープ剥離）の塗膜剥離面積率で評価した。
評点： ◎：剥離無し
○：剥離率 ５％未満
△：剥離率 ５％超、２０％未満
×：剥離率 ２０％超
これら、性能試験結果を表１に示す。表１から明らかなように、本発明による希土類金属元素のポリりん酸化合物と樹脂マトリックスを主成分とする処理皮膜は、比較例のクロメート皮膜と比較して同等の性能を有している。従って、６価クロムを全く含まない化成処理皮膜として優れた性能を発揮するものである。
【００２６】
【表１】
【発明の効果】
以上述べたように、本発明による希土類金属元素のポリりん酸化合物と樹脂マトリックスを主成分とする処理皮膜は、６価クロムを含有する皮膜と同等の性能を示すものである。これにより、クロメート皮膜と同等の性能を有し、環境付加を大幅に低減させた表面処理金属板および金属表面処理液を提供できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface-treated metal plate having a coating layer that is excellent in corrosion resistance and does not contain hexavalent chromium, and a treatment liquid therefor.
[0002]
[Prior art]
Conventionally, cold-rolled steel sheets, galvanized steel sheets, zinc-based alloy-plated steel sheets, aluminum-plated steel sheets, etc. used for applications such as automobiles, home appliances, and building materials have chromate coatings on their surfaces in order to impart rust prevention properties. It is a common practice to coat Examples of the chromate treatment include electrolytic chromate and coating chromate. Electrolytic chromate has been performed by, for example, subjecting a metal plate to cathodic electrolysis using a bath containing chromic acid as a main component and various anions such as sulfuric acid, phosphoric acid, boric acid and halogen. In addition, the coating type chromate has a problem of elution of chromium from the chromate-treated metal plate, so that a solution in which a part of hexavalent chromium is reduced to trivalent in advance or a solution in which the ratio of hexavalent chromium to trivalent chromium is specified. It has been carried out by adding an inorganic colloid or an anion to obtain a treatment liquid and immersing the metal plate therein or spraying the treatment liquid onto the metal plate.
[0003]
Among the chromate films, the chromate film formed by electrolysis has little elution of hexavalent chromium, but it cannot be said to have sufficient anticorrosion properties. In particular, when the film damage during processing is large, the corrosion resistance is lowered. On the other hand, the metal plate coated with the coating type chromate film has high corrosion resistance, and particularly excellent in the corrosion resistance of the processed part, but elution of hexavalent chromium from the chromate film is a serious problem. If an organic polymer is coated, elution of hexavalent chromium is considerably suppressed, but it is not sufficient. Further, in the method generally called resin chromate as disclosed in JP-A-5-230666, although improvement in the elution suppression of hexavalent chromium is observed, a very small amount of elution is unavoidable.
Thus, in order to completely suppress the elution of hexavalent chromium, it is necessary to develop a rust preventive film having a function equivalent to that of a conventional chromate film containing hexavalent chromium without using hexavalent chromium. .
[0004]
[Problems to be solved by the invention]
An object of the present invention is to solve these problems and to provide a surface-treated metal plate that can be replaced with a chromate film and a treatment liquid thereof.
[0005]
[Means for Solving the Problems]
The generic chemical conversion coating to replace the current chromate treatment designed in hexavalent chromium at all free system, and in order to solve the above problems, the inventors have found that extensive research, polyphosphoric acid compound of a rare earth metal element or It has been found that these mixtures and a film mainly comprising a resin matrix that physically holds them on the surface of the metal plate and has adhesion to the metal plate are effective in inhibiting corrosion of the metal plate.
[0006]
The gist of the present invention is as follows.
(1) Rare earth metal element polyphosphate compound or a mixture thereof, and these are physically held on the surface of the metal plate and coated with a film whose main component is a resin matrix having adhesion to the metal plate. The surface treatment metal plate characterized by the above-mentioned.
(2) A metal surface treatment liquid comprising a polyphosphate compound of a rare earth metal element or a mixture thereof and a resin matrix component as main components.
(3) rare earth metal element is lanthanum, cerium, above, wherein the yttrium (1) Symbol mounting surface treated metal plate.
(4) the (2) metallic surface treating solution of, wherein the rare earth metal element is lanthanum, cerium, yttrium.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The rare earth metal element has a corrosion prevention function although the mechanism is not clear. All rare earth metal elements can be used in the rare earth metal element compound or a mixture thereof (hereinafter abbreviated as “rare earth metal element compound”) used in the present invention, and the valence of the rare earth metal is not particularly limited. From the viewpoint of ease of handling, lanthanoids and / or yttrium are preferable, lanthanum or cerium is more economically preferable, and tetravalent cerium having combined oxidizing power is more preferable. Cerium is effective in suppressing the cathodic reaction, and the effect is further increased when tetravalent cerium is used.
[0008]
The rare earth metal element polyphosphate compound used in the present invention is a rare earth metal element polyphosphate compound or polyhydrogen phosphate compound or a mixture thereof (hereinafter abbreviated as "rare earth metal element polyphosphate compound"). Is preferable. The polyphosphate compounds of rare earth metal elements, called fingers compound with polyphosphoric acid ion and rare earth metal element, the polyphosphate hydrogen compound referred to finger a compound containing hydrogen on a part of the cation. Since these polyphosphate compounds and / or polyphosphate compounds form a paste-like, possibly non-crystalline (amorphous) inorganic polymer, they have process-following properties even when they are formed. , since it is possible to suppress corrosion by its barrier effect, it is possible to form a passive film of forming a passive film of phosphate film type by an excess of polyphosphoric acid, and an oxide film type, Furthermore, an inorganic corrosion-resistant chemical conversion film having high anticorrosion performance can be obtained .
[0009]
The rare earth metal element polyphosphate compound used in the present invention preferably has poor water solubility in order to provide long-term corrosion resistance, and the solubility of the rare earth metal element polyphosphate compound in water is pH 6-7 and the rare earth metal element. It is preferably 0.01 mol / l or less in terms of element. More preferably, when the pH is 5 to 8 and the solubility is 0.01 mol / l or less in terms of rare earth metal elements, the corrosion resistance can be maintained for a long time. If the solubility in water at pH 6-7 is more than 0.01 mol / l, the polyphosphate compound of rare earth metal elements is easily eluted from the film in wet environments such as rainwater and condensation, so long-term corrosion resistance in wet environments The performance is lowered.
[0010]
Moreover, in order to provide the corrosion resistance of a process part and a damage part, the rare earth metal element compound which becomes water-soluble in an acidic region is preferable. Specifically, the solubility of the rare earth metal element polyphosphate compound at a pH of 3 or less is preferably 0.1 mol / l or more in terms of the rare earth metal element. The function of selectively repairing corrosion progressing parts such as processed parts and scratched parts by dissolving 0.1 mol / l or more in response to a decrease in the pH of the corrosion occurring part and the rare earth metal polyphosphate compound dissolved Can be granted. If it is less than 0.1 mol / l, when the film is damaged by severe processing and exposed to extremely severe corrosive environment, the supply of the polyphosphate compound of rare earth metal element to the corroded area becomes insufficient, and the corrosion resistance becomes low. Lower.
[0011]
The rare earth metal element polyphosphate compound used in the present invention can be used by adding one kind in the same film, but a rare earth metal element or a plurality of rare earth metal elements in which polyphosphoric acid is changed. It is also possible to add a polyphosphoric acid compound. The addition of multiple rare earth metal polyphosphate compounds can be used in a wide variety of corrosive environments, but there are practically limited film thicknesses due to film properties such as manufacturing costs and weldability. Since the absolute amount per unit area of the rare earth metal element polyphosphate compound added to the coating is limited, the amount and type must be optimized.
[0012]
The amount of the rare earth metal polyphosphate compound contained in the coating on the metal plate cannot be limited because the required addition amount varies depending on the required corrosion resistance, but it is 1 mg / m 2 or more in terms of rare earth metal. I just need it. If it is less than 1 mg / m 2 , the effect of addition is insufficient, and improvement in corrosion resistance as a film is not observed. Moreover, even if it adds exceeding 10 mg / m < 2 >, since the corrosion-resistance improvement effect will be saturated, 10 mg / m < 2 > is enough in consideration of economical efficiency.
[0013]
The presence form of the polyphosphate compound of the rare earth metal element in the treatment liquid depends on the solvent used, pH, temperature, and concentration, but a dissolved state or a colloidal form finely dispersed in the treatment liquid is preferable. Other than these, when the film is formed, the dispersion state of the polyphosphate compound of the rare earth metal element becomes non-uniform, and the portion where the amount of the polyphosphate compound of the rare earth metal element is small tends to corrode. The average particle diameter when the rare earth metal element polyphosphate compound is finely dispersed in a colloidal form is preferably 1 μm or less, more preferably 0.5 μm or less, and particularly preferably 0.2 μm or less. When the particle size is 1 μm or more, the dispersion state of the polyphosphate compound of the rare earth metal element in the treatment solution or in the film is not uniform, and the film tends to be broken starting from the particles when processed, and the corrosion resistance. Is significantly worse.
[0014]
As the resin matrix component used in the present invention, the dispersion stability of the rare earth metal element polyphosphate compound in the treatment liquid is not significantly impaired, and the rare earth metal element polyphosphate compound is physically metallized. Any material can be used as long as it is held on the surface and has adhesion to the metal plate, and is not particularly limited. In general, acrylic, epoxy, and olefin-based organic resins are given as examples. As the form, water-soluble, emulsion resin dispersed in water, latex, and the like can be appropriately selected.
[0015]
In order to improve the performance of the film or treatment liquid of the present invention, an organic corrosion inhibitor, a passivated film formation aid, a surfactant such as a dispersant or an antifoaming agent, and other additives should be used in combination. You can also. Phosphoric acid, polyphosphoric acid as passivating film forming aid, calcium hydroxide, calcium carbonate, calcium oxide, zinc phosphate, potassium phosphate, calcium phosphate, calcium silicate, zirconium silicate as additive Aluminum phosphate, zirconium phosphate, TiO 2 , SiO 2 , Al 2 O 3 and the like can be added. The treatment liquid for forming the film of the present invention is basically composed of a rare earth metal element polyphosphate compound, a matrix component and a solvent, and the concentration and pH of the treatment liquid are not particularly limited. The solvent can be selected from either aqueous or volatile organic compounds. However, the water system is preferable in consideration of the working environment.
[0016]
The method for producing the surface-treated metal plate of the present invention is not particularly limited as long as the treatment liquid is applied to the surface of the metal plate and dried. For example, currently used chromate treatment coating equipment and paint coating equipment can be used as they are, and no special equipment is required. It is also possible to form a film by applying manually using a brush or a bar coater and drying. Although drying conditions cannot be generally limited, it is sufficient that the solvent contained in the treatment liquid is dried at least in a temperature range in which the resin matrix component contained therein is not decomposed. For example, the metal plate surface arrival temperature is preferably in the range of 50 ° C to 200 ° C.
[0017]
Although the film thickness cannot be limited because it varies depending on the application, it is preferably 0.01 μm or more. More preferably, it is 0.1 μm or more. If it is less than 0.01 μm, the corrosion resistance is not sufficient. However, even if the film thickness exceeds 10 μm, the effect of improving corrosion resistance is saturated, so 10 μm is sufficient in consideration of economy.
Although the metal plate which is the object of the present invention is not particularly limited, for example, hot dip galvanized steel sheet, hot dip zinc-iron alloy plated steel sheet, hot dip zinc-aluminum-magnesium alloy plated steel sheet, hot dip aluminum-silicon alloy plated steel sheet, hot lead soot alloy Surface-treated steel sheets such as galvanized steel sheets such as galvanized steel sheets, electrogalvanized steel sheets, electrogalvanized nickel alloy plated steel sheets, electrogalvanized iron alloy plated steel sheets, electrogalvanized steel sheets such as electrogalvanized chromium alloy plating, cold rolled steel sheets and zinc It can be applied to metal plates such as aluminum and magnesium.
[0018]
【Example】
Polyphosphoric acid compound of a rare earth metal element
(1) Polyphosphoric acid / lanthanum compound (abbreviation: PP-La)
An aqueous lanthanum chloride solution and polyphosphoric acid (manufactured by Showa Chemical Co., Ltd .: average molecular weight of about 338) were sufficiently mixed at a molar ratio of La / P at a rate of 1/6 and then heated at 200 ° C. for 12 hours.
[0019]
( 2 ) Polyphosphoric acid / cerium (III) compound (abbreviation: PP-Ce)
A cerium chloride aqueous solution and polyphosphoric acid (manufactured by Showa Chemical Co., Ltd .: average molecular weight of about 338) were sufficiently mixed at a molar ratio of Ce / P at a ratio of 1/6, and then heated at 200 ° C. for 12 hours.
( 3 ) Polyphosphate / cerium (IV) compound (abbreviation: PP-CeIV)
After dissolving diammonium cerium (IV) nitrate in polyphosphoric acid (Showa Chemical Co., Ltd .: average molecular weight of about 338) (molar ratio Ce / P, 1/6 ratio), the mixture was heated at 200 ° C. for 12 hours.
[0020]
Resin matrix (A) Block copolymer poly (methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate) -poly (styrene, methyl methacrylate, butyl methacrylate, butyl acrylate) -poly (methacrylic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate) ) A block copolymer (solvent: tetrahydrofuran) was produced by a living anionic polymerization method.
(B) Acrylic emulsion A commercially available water-dispersible carboxyl group-containing acrylic emulsion resin (manufactured by Nippon Synthetic Rubber Co., Ltd .: resin solid content 50% by weight) was used.
(C) SBR latex Commercially available water-dispersed carboxyl group-containing SBR latex (manufactured by Nippon Synthetic Rubber Co., Ltd .: resin solid content 50% by weight) was used.
[0021]
Preparation of Treatment Solution The above-described rare-earth metal element polyphosphate compound, resin matrix, and orthophosphoric acid or colloidal silica solution (manufactured by Nissan Chemical Co., Ltd., ST-O) were blended as a bath. For comparison, a simple resin matrix was also prepared. Table 1 shows the composition of each bath. The concentration of the building bath is 100 g / l for the rare earth metal polyphosphate compound in terms of rare earth metal, 100 g / l for the resin matrix in terms of solid content, 20 g / l for orthophosphoric acid as H 3 PO 4 , colloidal silica Was standardized to 5 g / l in terms of SiO 2 .
[0022]
Film Forming Method Each of the treatment baths described above was applied onto a steel plate and dried to form a film. The coating amount on the steel sheet was unified to about 0.5 μm in terms of film thickness. The steel plates used were GI (hot dip galvanized steel sheet, plating adhesion amount: 90 g / m 2 ), EG (electrogalvanized steel sheet, plating adhesion amount: 20 g / m 2 ), SZ (hot galvanized aluminum alloy plating steel sheet, plating adhesion) Amount: 90 g / m 2 , Zn / Al = 95.2 / 4.8), AL (molten aluminum-silicon alloy plated steel sheet, plating coverage: 120 g / m 2 , Al / Si = 90/10), CR ( Cold-rolled steel sheet) was used. In order to compare with the chromate-treated steel sheet, as the chromate treatment solution, a treatment solution containing 30 g / 1 of partially reduced chromic acid based on starch in terms of CrO 3 , 40 g / l of SiO 2 and 20 g / l of orthophosphoric acid. Was applied onto the steel sheet and dried to form a film so that the amount was about 50 mg / m 2 in terms of metallic chromium. The coating was performed using a bar coater and dried at an atmospheric temperature of 200 ° C. for 30 seconds.
[0023]
Film Performance Evaluation Method (I) Flat plate corrosion resistance was evaluated by rust generation rate after spraying 5%, 35 ° C. salt water on a sample. The spray period was 10 days for GI, EG, and SZ, 15 days for AL, and white rust occurrence rate for CR, and 5 days for CR.
Score: ◎: No rust occurrence ○: Rust incidence less than 5% △: Rust incidence more than 5%, less than 20% ×: Rust occurrence more than 20%
[0024]
(II) After the sample was processed with Erichsen 7 mm, the corrosion resistance of the processed part was evaluated based on the rust generation area after spraying 5%, 35 ° C. salt water. The spray period was 10 days for GI, EG, and SZ, 15 days for AL, and the white rust occurrence rate for CR was 5 days, and the red rust occurrence rate for CR was 5 days.
Score ◎: Rust incidence 0%
○: Rust occurrence rate less than 5% △: Rust occurrence rate 5% or more, less than 20% ×: Rust occurrence rate 20% or more
[0025]
(III) Coating adhesion The coating film of the base test (10 mm x 10 mm cut of 1 mm square board and tape peeling) after applying and baking a melamine-alkyd paint about 20 μm thick on the sample and immersing in boiling water for 30 minutes The peel area ratio was evaluated.
Score: ◎: No peeling
○: Peeling rate less than 5%
Δ: Exfoliation rate over 5%, less than 20%
X: Peeling rate over 20% These performance test results are shown in Table 1 . Table 1 or found apparent, treatment film composed mainly of poly phosphoric acid compound and the resin matrix of the rare earth metal element according to the invention has a comparable performance compared to chromate film of Comparative Example. Therefore, it exhibits excellent performance as a chemical conversion film containing no hexavalent chromium.
[0026]
[Table 1]
【The invention's effect】
As described above, the treatment film mainly composed of the polyphosphate compound of rare earth metal element and the resin matrix according to the present invention exhibits the same performance as the film containing hexavalent chromium. As a result, it is possible to provide a surface-treated metal plate and a metal surface treatment liquid that have the same performance as a chromate film and have greatly reduced environmental load.
Claims (4)
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14979397A JP3962123B2 (en) | 1997-06-09 | 1997-06-09 | Organic surface treatment metal plate and organic metal surface treatment liquid |
| US09/093,109 US6190780B1 (en) | 1996-02-05 | 1998-06-08 | Surface treated metal material and surface treating agent |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14979397A JP3962123B2 (en) | 1997-06-09 | 1997-06-09 | Organic surface treatment metal plate and organic metal surface treatment liquid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10337530A JPH10337530A (en) | 1998-12-22 |
| JP3962123B2 true JP3962123B2 (en) | 2007-08-22 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14979397A Expired - Fee Related JP3962123B2 (en) | 1996-02-05 | 1997-06-09 | Organic surface treatment metal plate and organic metal surface treatment liquid |
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| EP1587885A2 (en) * | 2003-01-17 | 2005-10-26 | University of Missouri Curators, Office of Tech. & Spec. Projects | Corrosion resistant coatings containing carbon pigments |
| JP5320666B2 (en) * | 2006-06-22 | 2013-10-23 | 新日鐵住金株式会社 | Galvanized steel sheet for back cover of display device using thin display panel |
| JP2012087213A (en) * | 2010-10-19 | 2012-05-10 | Nippon Parkerizing Co Ltd | Hydrophilic film for metal material, hydrophilization-treating agent, and hydrophilization-treating method |
| CN103978204B (en) * | 2014-04-30 | 2016-08-31 | 北京理工大学 | Light rare earth metal antioxidation method |
| AU2021432360A1 (en) | 2021-03-08 | 2023-09-21 | Nippon Steel Corporation | Coated and plated steel sheet or coated and plated steel strip |
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1997
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| JPH10337530A (en) | 1998-12-22 |
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