JP3801470B2 - Rust preventive containing water dispersible metal surface treatment agent, surface treatment metal material and method for producing the same - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は耐食性、塗料密着性、耐アルカリ性等の基本性能のみならず、耐溶剤性、耐傷付き性に優れる表面処理金属材と、その表面処理金属材を得ることができる貯蔵安定性に優れた防錆剤含有の水分散性金属表面処理剤と製造方法に関する。
【０００２】
【従来の技術】
最近の家電用表面処理金属材、特に亜鉛系めっき鋼板などに対し、耐指紋性、耐食性、耐傷つき性等、所謂、表面外観品位に対する要求レベルが年々高まってきており、それに伴い表面の実用機能を高めることが可能な表面処理剤の開発が急ピッチで進められている。そのため、例えば、近年、金属の後処理や塗装下地処理技術において、リン酸塩処理にかわり、クロメート処理が主流となっているが、最近では環境問題の観点からこのクロメートの難溶化と、更には触っても指紋が付かない、目立たない、そこから発錆しない、取り扱い疵が付きにくい、溶剤で拭いても表面機能が低下しない、後塗装性が良い等、金属表面の多機能かつ高性能化の傾向は年々高まるばかりである。特に、金属後処理用の表面処理剤については、近年技術の改善が目覚しく、ノンエキストラ（価格の高騰化がない）での高機能性を付与した表面処理剤やそれらを施した高機能金属材が市場提供されるようになった。
【０００３】
耐傷付き性を改善する方策の開示例としては、特開平７−１７１４９８号公報および特開平１０−１３０８６１号公報がある。前者は、粒径と融点を特定した球形のポリエチレンワックスの粒子とシリカ粒子とを、活性水素を分子内に持つウレタン樹脂に常温架橋型のエポキシ樹脂を配合した樹脂中に添加してなる塗料組成物を使用して金属材の上層に薄膜を形成させることを特徴とした打ち抜き加工性にすぐれる樹脂塗装金属材に関する。また後者は、ケイ酸アルカリ金属塩、ケイ酸コロイド、固形潤滑剤および有機樹脂（シランカップリング剤）をそれぞれ特定量配合してなることを特徴とする表面処理金属材に関する。両者は、いずれも家電オーディオ製品向け深絞り用金属材として市場提供しようとするための技術である。
【０００４】
また、リン酸塩やクロム酸塩を使用しないため無公害で、かつ、金属表面に優れた耐食性や塗料密着性を付与した例としては特開平１０−１７６１１９号公報がある。この技術は、平均分子量を特定した水性のポリエステル樹脂とエチレン−エチレン性不飽和カルボン酸共重合体アルカリ金属中和物（アイオノマー）の水分散性樹脂にエチレン性不飽和単量体を重合して得られる金属表面処理剤に関し、樹脂の配合比を特定することで金属の耐食性および塗料密着性を向上させようとするものである。
【０００５】
さらに、クロメート処理を施した亜鉛または亜鉛系めっき鋼板の経時黒変防止対策も重要である。例えば、特開平６−２４６２２９号公報、特開平８−３９７２５号公報、特開平９−１８７８８３号公報および特開平９−１８７８８４号公報では、いずれも下地クロメート処理の上に有機系の複合クリアー樹脂を薄膜塗布することにより、亜鉛めっき層の腐蝕を防ぎ、黒く変色することを防止する技術を開示している。
【０００６】
しかし何れの上記従来技術を使用しても、耐食性、塗料密着性および耐アルカリ性を損なうことなく、耐溶剤性、耐傷付き性および耐型カジリ性を同時に満足させた表面処理金属材を得ることは困難であった。
【０００７】
【発明が解決しようとする課題】
上記従来技術による有機被膜は、（１）処理剤自身が長期安定性に欠ける（ゲル化、かびが生える等）、（２）速乾性に劣る、（３）薄膜だと疵付いて破壊されやすい、（４）耐溶剤性は概して低い、（５）無塗油の深絞り加工において、素材の加工に塗膜が追従できず板破断を起こす、（６）耐アルカリ性が劣る、等の難点がある。これらの難点は、従来技術が採用している、樹脂を水に分散させるために用いる乳化剤に原因があり、この乳化剤でディスパージョン化した水分散性樹脂と熱硬化性の架橋剤とを用いる限り少なからず起こり得るものと考えられる。
【０００８】
したがって本発明の目的は、耐アルカリ性、塗料密着性および耐食性を損なうことなく、耐溶剤性、耐傷付き性、型カジリ性、深絞り加工性、ポストコート性等を同時に高位に満足させさせた表面処理金属材、およびその表面処理金属材を得ることができる貯蔵安定性に優れた水分散性金属表面処理剤と製造方法を提供することにある。
【０００９】
【課題を解決するための手段】
本発明者らは、前記課題を解決するために鋭意研究と開発を繰り返した結果、バインダー用主樹脂としてエチレン−不飽和カルボン酸共重合体のカルボキシル基を１価の金属陽イオンで中和したアイオノマー樹脂を用い、シリカおよび防錆剤、さらに塩素含有量を特定範囲に制御した水溶性の多官能エポキシ基含有化合物（以下、単に「水溶性エポキシ化合物」と称する）を配合することで、耐食性、塗料密着性、耐アルカリ性等の基本性能に加えて耐溶剤性、耐傷付き性に優れる表面処理金属材と、その表面処理金属材を得ることができる貯蔵安定性に優れた水分散性金属表面処理剤が得られることが分かり、本発明を完成するに至ったものである。
【００１０】
本発明の要旨とするところは、
（１）総固形分濃度が１０〜８０質量％でかつ固形分中４０〜９０質量％がアイオノマー樹脂、１〜１０質量％が水溶性多官能エポキシ基含有化合物、７〜４０質量％がアミノ基およびアンモニウムイオンの一方または両方を吸着させたシリカ（アミノ基またはアンモニウムイオン吸着型シリカ）、０．１〜１０質量％がチオカルボニル化合物またはバナジン酸アンモニウムから選ばれる少なくとも１種の防錆剤で構成された水分散性金属表面処理剤であって、前記アイオノマー樹脂がガラス転移点５０〜７０℃のエチレン−不飽和カルボン酸重合体でかつ含まれるカルボキシル基の４０〜６０％が１価の金属陽イオンで中和されたもので、さらに、前記水溶性多官能エポキシ基含有化合物中に含まれる塩素含有量が１質量％未満であることを特徴とする水分散性金属表面処理剤、
（２）水分散性金属表面処理剤のさらに固形分中０．５〜２０質量％が水分散性ポリオレフィン樹脂で構成されたものであることを特徴とする前記（１）に記載の水分散性金属表面処理剤、
（３）金属材表層に、固形分中４０〜９０質量％がアイオノマー樹脂、１〜１０質量％が水溶性多官能エポキシ基含有化合物、７〜４０質量％がアミノ基およびアンモニウムイオンの一方または両方を吸着させたシリカ、０．１〜１０質量％がチオカルボニル化合物またはバナジン酸アンモニウムから選ばれる少なくとも１種の防錆剤で構成された有機無機複合皮膜を乾燥質量として０．３〜５．０ｇ／ｍ2有し、前記アイオノマー樹脂がガラス転移点５０〜７０℃のエチレン−不飽和カルボン酸重合体で、かつ含まれるカルボキシル基の４０〜６０％が１価の金属陽イオンで中和されたもので、さらに、前記有機無機複合皮膜中の塩素含有量が０．１質量％未満であることを特徴とする表面処理金属材、
（４）有機無機複合皮膜のさらに固形分中０．５〜２０質量％が、水分散性ポリオレフィン樹脂で構成されたものであることを特徴とする前記（３）記載の表面処理金属材、
（５）金属材表面上層に、前記（１）または（２）に記載の水分散性金属表面処理剤を塗布、焼付処理を行い有機無機複合皮膜を乾燥質量として０．３〜５．０ｇ／ｍ2形成することを特徴とする表面処理金属材の製造方法、である。
【００１１】
【発明の実施の形態】
以下、本発明について詳細に述べる。
本発明の金属表面処理剤に使用する主樹脂開発の基本思想は、耐食性、塗料密着性および耐アルカリ性等の基本性能に加えて、
（１）アルカリ脱脂時、あるいはエタノールやメチルエチルケトン（ＭＥＫ）といった極性基の強い溶剤に対して容易に溶解剥離若しくは膨潤しないこと、加えて
（２）摺り疵が付きにくく、プレス加工等での厳しい加工でも容易に型カジリせず、しかも、基板金属の加工伸びに対して十分追従できること、
（３）しかもバインダー樹脂としてゲル化、沈殿のない貯蔵安定性に優れた水分散性樹脂であることにある。
【００１２】
更に、金属表面処理剤から形成される樹脂皮膜には、安価で塗料選択性のあるメラミンアルキッド等の低級なポストコート塗装に対しても十分な塗料密着性を発揮できるような機能付与が必須であるが、これについては、後述の水溶性エポキシ化合物を必須配合とした。また、耐食性付与にあたり、アミノ基またはアンモニウムイオン吸着型シリカを必須とし、更に高位の耐食性付与のためにチオカルボニル化合物、バナジン酸アンモニウム等の防錆剤を配合した。
【００１３】
本発明で使用する１価の金属陽イオンで中和したアイオノマー樹脂は、エチレンと不飽和カルボン酸を１５０〜２７０℃、９８〜２４５ＭＰａ（１０００〜２５００Ｋｇ／ｃｍ2）の高温高圧下で共重合反応させ、得られたエチレン−不飽和カルボン酸共重合体のカルボン酸を１５０〜３００℃の高温下で金属水酸化物等と反応させ、側鎖に有するカルボキシル基の４０〜６０％を１価の金属陽イオンで中和させることによって得られる水分散性アイオノマー樹脂である。このアイオノマー樹脂の主骨格を構成するエチレン−不飽和カルボン酸共重合体は、グラフト共重合体でもよいが、透明性の点でランダム共重合体が好ましい。
【００１４】
エチレン−不飽和カルボン酸共重合体の一成分である不飽和カルボン酸としては、炭素数３〜８の不飽和カルボン酸が挙げられる。具体例としては、アクリル酸、メタクリル酸、マレイン酸、フマール酸、イタコン酸、クロトン酸、イソクロトン酸、シトラコン酸、アリルコハク酸、メサコン酸、グルタコン酸、ナジック酸、メチルナジック酸、テトラヒドロフタール酸、メチルヘキサヒドロフタル酸が挙げられる。これらの中でも、メタクリル酸が好ましい。
【００１５】
上記アイオノマー樹脂の主骨格を構成するエチレン−不飽和カルボン酸共重合体は、エチレンと不飽和カルボン酸に加えて第３成分を含んでいてもよい。このような第３成分との例しては、（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸イソブチル等の不飽和カルボン酸エステル、酢酸ビニル等のビニルエステルが挙げられる。なお、ここで用いる「（メタ）アクリル」という表現は、「アクリルまたはメタクリル」を意味する。
【００１６】
上記エチレン−不飽和カルボン酸共重合体におけるエチレンの含有量は、８〜９５質量％であり、好ましくは８〜２５質量％である。また、エチレン−不飽和カルボン酸共重合体が上記第３成分を含む場合、その量は４０質量％以下に限定することが好ましい。
【００１７】
上記アイオノマー樹脂の中和に用いる金属陽イオンとしては、良好な乳化性を有するアイオノマー樹脂が得られる点でＬｉ+、Ｎａ+、Ｋ+等、１価の金属陽イオンが推奨されるが、中でもＮａ（ナトリウム）イオンが好ましい。金属陽イオンで中和されたカルボキシル基の割合、すなわち中和度は、塗膜の密着性に優れるとともに、良好な水分散体が得られる点で４０〜６０％とする。４０％未満では良好な水分散体が得られにくく、６０％を越えると塗膜の密着性が劣るため好ましくない。
【００１８】
この４０〜６０％に中和調整されたエチレン−不飽和カルボン酸共重合体のガラス転移点（以下、Ｔｇという）は、５０〜７０℃である必要があり、好ましくは５０〜６０℃である。Ｔｇが５０℃未満では、樹脂皮膜としての耐疵付き性が低下し、プレス加工などで皮膜が破れて型カジリを起こし易く、また、Ｔｇが７０℃を超えると皮膜の柔軟性が不足し、加工による皮膜のひび割れなどが発生するため好ましくない。本発明においては、ＴｇはＪＩＳ Ｋ ７１２１に従って測定される。
【００１９】
上記水分散性アイオノマー樹脂の（固形分換算）配合量は、全固形分に対する百分率で４０〜９０質量％、好ましくは５０〜８０質量％である。この割合が４０質量％未満では、金属被塗物に対して均一な皮膜の形成が難しくなることから、耐食性が著しく低下する。一方、９０質量％を超えると、処理液の増粘が影響して膜厚の均一制御が難しくなるため、プレス加工性に劣るなどの問題が生じる他、塗装仕上がり外観の低下や塗装設備の洗浄に時間がかかる等、塗装作業上の問題が生じるため好ましくない。
【００２０】
一方、本発明で用いる水溶性エポキシ化合物は、耐アルカリ性およびポストコート時の塗膜の二次密着性を安定して高位に得るために使用するものである。水溶性エポキシ化合物の全固形分に対する百分率は１〜１０質量％であるが、好ましくは３〜７質量％である。この配合割合が１質量％未満では、皮膜の素地密着性やメラミンアルキッド系塗料など低級のポストコートの沸水二次密着性が不十分となる。一方、１０質量％を超えると塗膜が過剰に硬質化し、加工によりひび割れが入り易くなったり塗膜剥離しやすくなる。
【００２１】
上記水溶性エポキシ化合物は、含まれるグリシジル基が、塗装後の加熱によりアイオノマー樹脂のカルボキシル基と反応し、素地金属や家電用途のワンコート・ワンベーク（１Ｃ１Ｂ）塗装のポストコート等に対する密着性を向上させる利点がある。官能基数としては、３〜４官能のものが好ましく、その例としてはペンタエリスリトールグリシジルエーテルやグリセロールポリグリシジルエーテル等であって塩素量を１質量％未満に調整したものが挙げられる。しかし、単官能のエポキシ化合物では、アイオノマー樹脂とともに配合された金属表面処理剤から形成した塗装皮膜において、メラミンアルキッド樹脂塗料のような低級なポストコートとの二次密着性の機能を改善することは困難である。また、官能基が５を超えると、架橋密度が高まりすぎて皮膜の硬質化が進み、加工性が著しく低下するため耐食性の劣化を招くことがある。
【００２２】
水溶性エポキシ化合物の粘度については、塗装作業性の面から２５℃で４００ｍＰａ・ｓ以下、さらには３５０ｍＰａ・ｓ以下のものが好適である。またエポキシ当量は６．０〜７．５ｅｑ／ｋｇ、さらには６．２〜７．１ｅｑ／ｋｇの範囲のものが反応性の面から好適である。
【００２３】
ここで、従来使用されていた多官能エポキシ化合物は、原料であるエピクロルヒドリン由来の塩素が多く残留している。そのため、この塩素を多量に含む金属表面処理剤は貯蔵安定性が悪く、時間の経過とともに沈殿物を生じるほか、この処理液で形成された皮膜は耐食性等の性能が劣る等の問題点があった。
【００２４】
そこで本発明では、製造時に塩素量を１質量％未満に調整した水溶性多官能エポキシ化合物を使用する。しかも、水溶性多官能エポキシ樹脂中に含まれる塩素の量を１質量％以下、さらに処理皮膜中に含まれる塩素の量を０．１質量％以下に調節することで、処理剤の長期安定性のみならずこの処理剤を処理することによって得られる表面処理金属板の耐食性を改善することが可能になる。
【００２５】
また、本発明で使用するアミノ基またはアンモニウムイオン吸着型シリカとしては、粒径１０〜２０ｎｍの微粒子状シリカの表面にアミノ基および／またはアンモニウムイオンを吸着させてｐＨ９．０〜１０．５に調整し、水中に分散させたコロイダルシリカが最適である。ｐＨの調整においては、有機アミノ化合物またはアンモニア水のいずれを用いてもよいが、作業性、作業環境の面から有機アミノ化合物の使用が好ましい。このような有機アミノ化合物としては、アミノアルコールやジエタノールアミンなどを挙げることができる。
【００２６】
該シリカの（固形分換算）配合量は、全固形分に対する百分率で７〜４０質量％、好ましくは１５〜３５質量％である。シリカが７質量％未満では皮膜の耐疵付き性や耐食性の低下が生じ、４０質量％を超えると塗膜が固くなり過ぎて柔軟性が低下し、プレス曲げ加工などにおいて曲げ部の塗膜にヘアークラック等が発生しやすくなるため耐食性も低下する。
【００２７】
本発明で使用する防錆剤は、外的腐食因子の抑制防止を目的として、
（１）腐食因子の浸透防止、
（２）防錆皮膜の優れた密着性、
（３）防錆イオンによる素地金属表面の不動態化、
（４）防錆皮膜への耐水性付与、
などの諸特性を満足し得る必要がある。そのような防錆剤がチオカルボニル化合物、およびバナジン酸アンモニウムの少なくとも１種からなるものであり、この配合量は０．１〜１０質量％、好ましくは１〜５質量％である。これが０．１質量％未満では、金属素材の耐食性が十分でなく、１０質量％を超えると増粘して塗料化が困難になるか、塗装しても、高生産性のライン下では連続して均一な塗装外観を得ることが困難である。なお、防錆剤としてチオカルボニル化合物を用いる際には、その配合量の０．１〜１０倍量を目安としてリン酸イオンを併用してもよい。リン酸イオンは、水溶液中でリン酸イオンを生じる任意のリン酸化合物から生じさせることができる。そのようなリン酸化合物としては、例えば、リン酸、リン酸アンモニウム、リン酸カリウム、リン酸ナトリウムなどを使用することができる。
【００２８】
上記チオカルボニル化合物とは、下記に示すチオカルボニル基（Ｉ）
【００２９】
【化１】
を有する化合物を指し、その中でも下記に示す窒素原子や酸素原子を同時に有するチオカルボニル基（ＩＩ）が好ましい。
【００３１】
【化２】
また、水溶液中や酸またはアルカリの存在下の条件においてチオカルボニル化合物を形成することのできる化合物も使用することができる。
上記チオカルボニル化合物の例としては、次の式（ＩＩＩ）
【００３３】
【化３】
で表されるチオ尿素およびその誘導体、例えばメチルチオ尿素、ジメチルチオ尿素、エチルチオ尿素、ジエチルチオ尿素、ジフェニルチオ尿素、チオペンタール、チオカルバジド、チオカルバゾン類、チオシアヌル酸類、チオヒダントイン、２−チオウラミル、３−チオウラゾール、次の式（ＩＶ）
【００３５】
【化４】
で表されるチオアミド化合物、例えばチオホルムアミド、チオアセトアミド、チオプロピオンアミド、チオベンズアミド、チオカルボスチリル、チオサッカリン、次の式（Ｖ）
【００３７】
【化５】
で表されるチオアルデヒド化合物、例えばチオホルムアルデヒド、チオアセトアルデヒド、次の式（ＶＩ）
【００３９】
【化６】
【００４０】
【化７】
で表されるチオ炭酸類、その他式（Ｉ）の構造を有する化合物、例えばチオクマゾン、チオクモチアゾン、チオニンブルーＪ、チオピロン、チオピリン、チオベンゾフェノンが挙げられる。なお、上記チオカルボニル化合物のうち水に溶解しないものは、アルカリ溶液で一旦溶解させた後、処理剤中に配合する。
【００４２】
なお、本発明の水分散性金属表面処理剤には、他の機能、たとえば潤滑性の付与を目的として水分散性のオレフィン樹脂系ワックスを、総固形分濃度に占める割合で０．５〜２０質量％添加することもできる。
【００４３】
また、本発明に係わる処理剤は、更に他の成分が配合されても良い。例えば、顔料、界面活性剤等を挙げることができる。また、樹脂成分、シリカ粒子、顔料との親和性を向上させ、更に樹脂成分と亜鉛めっきまたは鋼材との密着性等を向上させるためにシランカップリング剤を配合しても良い。
【００４４】
上記顔料としては、例えば酸化チタン、酸化亜鉛、酸化ジルコニウム、炭酸カルシウム、硫酸バリウム、アルミナ、カオリンクレー、カーボンブラック、酸化鉄等の無機顔料や有機顔料等を用いることができる。
【００４５】
上記シランカップリング剤としては、例えば、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−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トリエトキシシラン、γ−メタクリロキシプロピルトリエトキシシラン、Ｎ−[２−（ビニルベンジルアミノ）エチル]−３−アミノプロピルトリメトキシシラン等を挙げることができる。
【００４６】
上記各成分を含有する本発明の水分散性金属表面処理剤は、総固形分濃度１０〜８０質量％で使用することができる。固形分以外の組成は水がほとんどであるが、その他、揮発性ｐＨ調整剤等、塗装・焼付後に皮膜組成中に残らないもの全てを含む。上記総固形分濃度が１０質量％未満では皮膜厚を十分に確保することができず、８０質量％を超えると塗装作業性が悪くなるため安定した塗膜厚を確保することが困難になる。
【００４７】
本発明の水分散性金属表面処理剤の調製方法は、例えば、アイオノマー樹脂の水分散体に所定量のアミノ基またはアンモニウムイオン吸着型シリカを加え、水およびアルカリ成分を加えてｐＨを調整する。添加するアルカリ成分としては、乾燥過程でガス化して固形皮膜中にアルカリ分が残らないようにするため、有機アミノ化合物またはアンモニア水等のアルカリ水溶液が好ましい。また、本発明の処理剤はアルカリ性であればそのｐＨは問わないが、好ましくは約１０前後に調整したのち、所定量の水溶性エポキシ化合物を添加し、液温４０℃以下で約１０分間、ディスパー攪拌してよく混合する。なお、アイオノマー樹脂と水溶性エポキシ化合物の混合物を加熱溶融して一括乳化する手法もあるが、この手法は特に無機系防錆剤を共存させる場合には好ましくなく、沈殿物が発生することがあるので避けたほうがよい。
【００４８】
本発明の処理方法は、金属材料を本発明の水分散性金属表面処理剤で処理し、その後焼付けるものである。処理方法としては特に制限はないがロールコーター法が好ましく、その他、浸漬法、スプレー法等がある。塗膜の付着量は乾燥質量で０．３〜５．０ｇ／ｍ2とする。０．３ｇ／ｍ2未満では耐食性が劣化するため好ましくない。また、５．０ｇ／ｍ2を越えるものは経済的に好ましくない。また、焼付温度は８０〜１８０℃、焼付時間は２秒〜３０分、さらには４秒〜１０分が好ましい。
【００４９】
上記金属材料としては特に制限はなく、板状またはその他の形状の未処理鋼材、電気亜鉛めっき鋼材、溶融亜鉛めっき鋼材、ガルバリウム鋼材、アルミニウム材、アルミニウム合金材、その他銅材等の金属材料に適用可能である。さらに、本発明の対象の金属材料には、プラスチック材料に各種金属をラミネートした金属−プラスチック複合材料も含まれる。このようにして製造された本発明の表面処理金属材は、クロメート処理を施すことなく本発明の水分散性金属表面処理剤で被覆されているため、無公害かつ耐溶剤性、耐傷付き性およびポストコート性に優れたものとなる。
【００５０】
【実施例】
以下、実施例を挙げて本発明を具体的に説明する。
【００５１】
（実施例１〜１２１、比較例１〜３５）
＜水分散性金属表面処理剤の調製＞
エチレン−メタクリル酸共重合体１００ｇ〔溶融流れ指数（ＭＦＲ）が１９０℃で０．８ｇ／１０分、メタクリル酸含有量１５質量％〕、中和剤は水酸化ナトリウムを２５０℃で溶融してアイオノマー樹脂溶融物を用意し、これに水３００ｇを加えた後、１７０℃に加熱した内容積１リットルの耐圧ホモミキサーに、１０００ｒｐｍで攪拌しながら約２時間かけて仕込んだ。仕込み終了後、さらに１時間攪拌を継続して室温まで冷却しアイオノマー樹脂の水分散体を得た。
【００５２】
次に、エポキシ化合物として塩素含有量が１．０質量％未満で水溶化率１００％のペンタエリスリトールポリグリシジルエーテル（デナコールＥＸ−１４１０、ナガセ化成工業製）を、またシリカとして表面がアンモニウムイオンを吸着し、かつアルカリ性に制御されたコロイダルシリカを用意し、アイオノマー水分散体樹脂、エポキシ化合物およびシリカを表１〜４および表８に示す質量百分率で種々配合し、それらを５００ｒｐｍで６０分間ディスパー中で攪拌した。なお、表１〜４および表８中のアイオノマー樹脂およびコロイダルシリカの質量％は固形分に換算した値である。
【００５３】
そして攪拌の途中でアミノアルコールによってｐＨを１０に調整して攪拌を１０分継続行った後、防錆剤としてＡ：チオ尿素、Ｂ：１,３-ジエチル-２-チオ尿素、Ｃ：チオアセトアミド、Ｄ：２,２’-ジトリルチオ尿素、Ｅ：チオ安息香酸、Ｆ：チオアセトアルデヒド、Ｇ：バナジン酸アンモニウム、及びリン酸アンモニウムを表１〜４および表８に示す質量百分率で種々配合した。そして更に攪拌を続け、合計６０分間の攪拌が終了した後、２００メッシュフィルターで濾過し、そのろ液を（必要に応じて）純水で調整し、本実施例または比較例の水分散性金属表面処理剤とした。
【００５４】
＜鋼板への塗装＞
脱脂剤（「サーフクリーナー１５５」、日本ペイント社製）の２％水溶液を、６０℃で６０秒間スプレー後、水洗して乾燥された板厚１．２ｍｍの電気亜鉛めっき鋼板（目付量２０ｇ／ｍ2）の表面に、上記水分散性金属表面処理剤の固形皮膜が０．３〜５．０ｇ／ｍ2となるようバーコーターで塗布したのち、ガス炉の中で出口側板温が在炉時間２０秒で１２０℃になるよう塗膜の焼付処理を行い試験片を作製した。尚、付着量の測定は重量法で行った。
【００５５】
＜性能評価試験＞
１）耐アルカリ性
アルカリ脱脂剤（ＳＣ５３、日本ペイント社製）の２％水溶液に試験片の半分を、液温５５℃×１０分浸漬の後、水洗乾燥して塗膜外観の健全性、耐脱膜性を非浸漬部と比較観察した。
◎ ：塗膜異常なし、○：僅かに外観変色、△：部分脱膜、×：全面脱膜
【００５６】
２）耐白化性（塗膜の耐沸水試験）
試験片の半分を純水の沸騰水に２時間浸漬した後試験片を引き上げ、自然乾燥を待って浸漬部と非浸漬部の外観差を目視で判定した。
◎：外観の差なし、○：僅かに浸漬部に脱色あり、△：部分白化あり、×：全面白化
【００５７】
３）型カジリ性
円筒エリクセンプレスを使用。直径５０ｍｍ円筒、絞り比２．４、板厚１．０ｍｍ、クリアランス０．０ｍｍ、しわ押え圧力１．５トンで試験片の無塗油絞り抜けを行い、円筒胴部の型カジリ状況を観察。
◎ ：かじりなし、○：僅かにかじり、△：部分的なかじり、×：全面かじり
【００５８】
４）耐食性
ＪＩＳ Ｚ ２３７１に準拠した塩水噴霧試験をおこなった。エリクセン６ｍｍ押し出し加工部、平面部のある試験片（端面、裏面はテープシール）を作製し、塩水噴霧１６８時間後、白錆発生状況を評価した。
◎ ：錆なし、○：面積比５％以下、△：５〜３０％、×：３０％以上
【００５９】
５）ポストコート二次密着性
試験片にメラミンアルキッド樹脂系塗料（白色）を、乾燥膜厚２０〜２５μｍ、１２５℃×２０分の条件で焼き付けた後、沸騰した純水に３０分浸漬、２４時間室内放置した後、ＪＩＳ Ｋ ５４００に準拠した碁盤目試験で、試験片に１ｍｍ角の碁盤目を１００個密接して罫書き、粘着テープ（「セロテープ」、ニチバン社製）にて４５度方向に強制剥離した。
◎：剥離なし、○：僅かに剥離、△：部分剥離、×：全面剥離
【００６０】
６）耐溶剤性
ＳＵＳ丸棒端面にエタノールを含浸させた８枚重ねのガーゼを荷重１Ｋｇ×１０回（往復）、およびＭＥＫ（メチルエチルケトン）を含浸させて荷重１Ｋｇ×５０回（往復）擦った後の塗膜の溶解外観を特殊染料で染色し、その染色度の差から判定。
◎ ：異常なし、○：僅かに溶解、△：部分的溶解、×：全面溶解（素地露出）
【００６１】
７）処理剤の沈殿発生
全塩素量が異なるエポキシ化合物添加後、４０℃×３０日経時させた際の処理剤中の沈殿発生状況を評価
◎ ：異常なし、○：僅かに白濁するも沈殿なし、△：白濁増すも沈殿なし、×：沈殿大
【００６２】
処理剤の配合組成および評価結果を表１〜４および表８に示す。
これらの結果から、処理剤中のシリカ量が本発明の範囲を外れると、下限側では耐食性、上限側では絞り加工などのプレス加工性にダメージがあり、避けた方がよいことが分かる。また、アイオノマー樹脂の配合量が本発明の範囲を外れると、下限側では耐食性、プレス型カジリ性、メラミンアルキッドによるポストコートの二次密着性でダメージが大きく、上限側では絞り加工等のようなプレス加工に若干劣るため、好ましくないことが分る。
【００６３】
また、経時に対し、処理液中に発生する沈殿物は、水溶性エポキシ化合物中の塩素含有量が１質量％を越えると白濁もしくは沈殿することが分かる。また、塩素含有量を制御した水溶性エポキシ化合物については、その量が本発明の範囲を外れると、下限側ではポストコートの二次密着性が劣化し、上限側では耐アルカリ性、耐白化性、耐かじり性など、塗膜性能の全体的なレベルダウンを招くことが分かる。
【００６４】
さらに、アイオノマー樹脂のＴｇが本発明の範囲を外れると、下限側では皮膜が軟らかくなり耐型カジリ性が劣り、上限側では皮膜の柔軟性が不足し耐型かじり性に劣ることが分かる。アイオノマーの中和度については、本発明の範囲を外れると、下限側では処理液の安定性が劣化し、上限側ではポストコートの二次密着性が劣化することが分る。有機無機複合皮膜の付着量については、本発明の下限範囲を外れると、耐食性のみならず耐型かじり性や二次密着性が劣化することが分かる。
【００６５】
また、防錆剤の量が本発明の範囲を外れると、下限側では耐食性の低下が大きく、逆に上限を外れると型かじり性、ポストコートの二次密着性でダメージが大きい。
【００６６】
（実施例１２２〜２０６）（水性ワックスとして水分散性ポリオレフィン樹脂を添加した場合）
既述の各実施例および比較例用に製造した水分散性金属表面処理剤に、数平均分子量が１５００、粒径０．７μｍの水分散性ポリオレフィン樹脂（固形分換算）を表５〜７に示す質量百分率で種々配合し、５００ｒｐｍで３０分間ディスパー攪拌し、攪拌の途中でアミノアルコールによってｐＨの微調整をおこなった後、２００メッシュフィルターでろ過し、そのろ液を潤滑機能を付与した水分散性金属表面処理剤とした。これらの組成および評価結果を表５〜７に示す。
【００６７】
これらの結果から、潤滑剤であるポリオレフィン樹脂の添加は、本発明範囲内であれば他性能への影響は殆どなく、処理剤を構成するアイオノマー樹脂、シリカの作用効果もポリオレフィン樹脂添加前と同様の効果であることが分かる。
【００６８】
【表１】
【表２】
【表３】
【表４】
【表５】
【表６】
【表７】
【表８】
【発明の効果】
本発明の水分散性金属表面処理剤は、特定のアイオノマー樹脂、水溶性エポキシ化合物、シリカおよび非クロム系防錆剤を組み合わせて調製してあるため、４０℃以下において１ヶ月以上の高い貯蔵安定性を有する。また、めっき後処理製品等の本発明の表面処理金属材は、耐アルカリ性、塗料密着性および耐食性を損なうことなく、耐溶剤性、耐傷付き性、型カジリ性、深絞り加工性、ポストコート性等を満足させる。さらに、本発明の処理剤および表面処理金属材はクロムを含有しないため低公害である。このように耐食性、低公害性に優れた本発明の表面処理金属材は、家庭用電気製品や建材および自動車部品等の構成部材として好適である。[0001]
BACKGROUND OF THE INVENTION
The present invention is excellent not only in basic properties such as corrosion resistance, paint adhesion, and alkali resistance, but also in a surface-treated metal material excellent in solvent resistance and scratch resistance, and in storage stability capable of obtaining the surface-treated metal material. The present invention relates to a water dispersible metal surface treatment agent containing a rust inhibitor and a production method.
[0002]
[Prior art]
The demand level for so-called surface appearance quality such as fingerprint resistance, corrosion resistance, scratch resistance, etc. is increasing year by year for surface-treated metal materials for home appliances, especially zinc-based plated steel sheets. Development of a surface treatment agent capable of increasing the resistance is proceeding at a rapid pace. Therefore, for example, in recent years, chromate treatment has been the mainstream in place of phosphate treatment in metal post-treatment and paint base treatment technologies, but recently, in terms of environmental problems, this chromate is hardly soluble, and further Multi-functional and high-performance metal surface such as fingerprints do not stick even when touched, does not stand out, does not rust, does not easily wrinkle, does not deteriorate surface function even when wiped with solvent, and has good post-paintability The trend is growing year by year. In particular, surface treatment agents for post-treatment of metals have been remarkably improved in technology in recent years, and surface treatment agents that have been provided with high functionality with non-extra (no price increase) and high-performance metal materials with them. Became available on the market.
[0003]
As examples of disclosure of measures for improving the scratch resistance, there are JP-A-7-171498 and JP-A-10-130861. The former is a paint composition in which spherical polyethylene wax particles and silica particles whose particle size and melting point are specified are added to a resin in which a urethane resin having active hydrogen in the molecule is mixed with a room temperature crosslinking epoxy resin. The present invention relates to a resin-coated metal material having excellent punching processability, characterized in that a thin film is formed on an upper layer of a metal material using an object. The latter relates to a surface-treated metal material comprising a specific amount of each of an alkali metal silicate salt, a silicate colloid, a solid lubricant, and an organic resin (silane coupling agent). Both of these technologies are intended to be marketed as deep drawing metal materials for home appliance audio products.
[0004]
Japanese Patent Laid-Open No. 10-176119 discloses an example of using no phosphate and chromate and giving pollution-free and excellent corrosion resistance and paint adhesion to a metal surface. In this technology, an ethylenically unsaturated monomer is polymerized into a water-dispersible resin of an aqueous polyester resin having an average molecular weight specified and an alkali metal neutralized product (ionomer) of an ethylene-ethylenically unsaturated carboxylic acid copolymer. With respect to the obtained metal surface treating agent, it is intended to improve the corrosion resistance and paint adhesion of the metal by specifying the compounding ratio of the resin.
[0005]
Furthermore, it is also important to take measures to prevent blackening over time of zinc or zinc-based plated steel sheets subjected to chromate treatment. For example, in JP-A-6-246229, JP-A-8-39725, JP-A-9-187883 and JP-A-9-18784, an organic composite clear resin is applied on the base chromate treatment. A technique for preventing corrosion of the galvanized layer and discoloration to black by applying a thin film is disclosed.
[0006]
However, using any of the above prior arts, it is possible to obtain a surface-treated metal material that simultaneously satisfies solvent resistance, scratch resistance and mold galling resistance without impairing corrosion resistance, paint adhesion and alkali resistance. It was difficult.
[0007]
[Problems to be solved by the invention]
The organic coating according to the above prior art is (1) the treatment agent itself lacks long-term stability (gelation, mold growth, etc.), (2) is inferior in quick-drying, and (3) it is easy to break when it is a thin film. (4) Solvent resistance is generally low, (5) In oil-free deep drawing, the coating film cannot follow the processing of the material, causing plate breakage, (6) Alkaline resistance is inferior, etc. is there. These difficulties are caused by the emulsifier used to disperse the resin in water, which is adopted by the prior art. As long as the water-dispersible resin dispersed with this emulsifier and a thermosetting cross-linking agent are used. It is thought that it can occur not a little.
[0008]
Therefore, the object of the present invention is to provide a surface that simultaneously satisfies a high level of solvent resistance, scratch resistance, mold galling, deep drawing workability, post-coating property, etc. without impairing alkali resistance, paint adhesion and corrosion resistance. An object of the present invention is to provide a treated metal material, a water dispersible metal surface treatment agent excellent in storage stability and a production method capable of obtaining the treated metal material.
[0009]
[Means for Solving the Problems]
As a result of repeating earnest research and development to solve the above problems, the present inventors neutralized the carboxyl group of the ethylene-unsaturated carboxylic acid copolymer with a monovalent metal cation as the main resin for the binder. Corrosion resistance by blending silica and rust preventive agent, and water-soluble polyfunctional epoxy group-containing compound whose chlorine content is controlled to a specific range (hereinafter simply referred to as “water-soluble epoxy compound”) using ionomer resin In addition to basic properties such as paint adhesion and alkali resistance, surface-treated metal materials with excellent solvent resistance and scratch resistance, and water-dispersible metal surfaces with excellent storage stability from which the surface-treated metal materials can be obtained It has been found that a treatment agent can be obtained, and the present invention has been completed.
[0010]
The gist of the present invention is that
(1) The total solid content concentration is 10 to 80% by mass, and 40 to 90% by mass in the solid content is an ionomer resin, 1 to 10% by mass is a water-soluble polyfunctional epoxy group-containing compound, and 7 to 40% by mass is an amino group. And silica adsorbing one or both of ammonium ions (amino group or ammonium ion adsorption type silica), 0.1 to 10% by mass is composed of at least one rust inhibitor selected from thiocarbonyl compounds or ammonium vanadate A water-dispersible metal surface treatment agent, wherein the ionomer resin is an ethylene-unsaturated carboxylic acid polymer having a glass transition point of 50 to 70 ° C., and 40 to 60% of the carboxyl groups contained therein are monovalent metal positive agents. It is neutralized with ions, and the chlorine content contained in the water-soluble polyfunctional epoxy group-containing compound is less than 1% by mass. Water dispersible metal surface treatment agent characterized,
(2) The water dispersibility described in (1) above, wherein 0.5 to 20% by mass in the solid content of the water dispersible metal surface treatment agent is composed of a water dispersible polyolefin resin. Metal surface treatment agent,
(3) On the metal material surface layer, 40 to 90 mass% of the solid content is an ionomer resin, 1 to 10 mass% is a water-soluble polyfunctional epoxy group-containing compound, and 7 to 40 mass% is one or both of an amino group and an ammonium ion. The organic / inorganic composite film composed of at least one rust preventive agent selected from a thiocarbonyl compound or ammonium vanadate having a dry weight of 0.3 to 5.0 g is prepared by adsorbing silica. / M 2 The ionomer resin is an ethylene-unsaturated carboxylic acid polymer having a glass transition point of 50 to 70 ° C., and 40 to 60% of the contained carboxyl groups are neutralized with a monovalent metal cation, Further, the surface-treated metal material, wherein the chlorine content in the organic-inorganic composite film is less than 0.1% by mass,
(4) The surface-treated metal material according to (3), wherein 0.5 to 20% by mass in the solid content of the organic-inorganic composite film is composed of a water-dispersible polyolefin resin,
(5) Applying the water-dispersible metal surface treatment agent according to (1) or (2) above to the metal material surface upper layer, baking treatment, and the organic-inorganic composite film as a dry mass of 0.3 to 5.0 g / m 2 It is a manufacturing method of the surface treatment metal material characterized by forming.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
In addition to basic performance such as corrosion resistance, paint adhesion, and alkali resistance, the basic idea of the development of the main resin used in the metal surface treatment agent of the present invention is:
(1) During alkaline degreasing, or not easily dissolved and peeled off or swollen with a solvent having a strong polar group such as ethanol or methyl ethyl ketone (MEK).
(2) Scratch is not easily attached, it is not easily squeezed even in severe processing such as pressing, and it can follow the processing elongation of the substrate metal sufficiently.
(3) Furthermore, the binder resin is a water-dispersible resin excellent in storage stability without gelation or precipitation.
[0012]
In addition, the resin film formed from the metal surface treatment agent must be provided with a function capable of exhibiting sufficient paint adhesion even for low-cost post-coat paint such as melamine alkyd, which is inexpensive and has paint selectivity. However, for this, a water-soluble epoxy compound described later is an essential blend. In addition, for imparting corrosion resistance, an amino group or ammonium ion adsorption type silica is essential, and a rust inhibitor such as a thiocarbonyl compound and ammonium vanadate is blended for imparting higher corrosion resistance.
[0013]
The ionomer resin neutralized with a monovalent metal cation used in the present invention contains ethylene and unsaturated carboxylic acid at 150 to 270 ° C. and 98 to 245 MPa (1000 to 2500 Kg / cm 2). 2 ) Under high temperature and high pressure, and the resulting carboxylic acid of the ethylene-unsaturated carboxylic acid copolymer is reacted with a metal hydroxide or the like at a high temperature of 150 to 300 ° C. to have a carboxyl group in the side chain. It is a water-dispersible ionomer resin obtained by neutralizing 40 to 60% of the above with a monovalent metal cation. The ethylene-unsaturated carboxylic acid copolymer constituting the main skeleton of the ionomer resin may be a graft copolymer, but a random copolymer is preferable in terms of transparency.
[0014]
As unsaturated carboxylic acid which is one component of an ethylene-unsaturated carboxylic acid copolymer, C3-C8 unsaturated carboxylic acid is mentioned. Specific examples include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid, isocrotonic acid, citraconic acid, allyl succinic acid, mesaconic acid, glutaconic acid, nadic acid, methyl nadic acid, tetrahydrophthalic acid, And methyl hexahydrophthalic acid. Among these, methacrylic acid is preferable.
[0015]
The ethylene-unsaturated carboxylic acid copolymer constituting the main skeleton of the ionomer resin may contain a third component in addition to ethylene and the unsaturated carboxylic acid. Examples of such a third component include unsaturated carboxylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, and isobutyl (meth) acrylate, and vinyl esters such as vinyl acetate. . The expression “(meth) acryl” used here means “acryl or methacryl”.
[0016]
The ethylene content in the ethylene-unsaturated carboxylic acid copolymer is 8 to 95% by mass, preferably 8 to 25% by mass. Moreover, when an ethylene-unsaturated carboxylic acid copolymer contains the said 3rd component, it is preferable to limit the quantity to 40 mass% or less.
[0017]
The metal cation used for neutralization of the ionomer resin is Li in that an ionomer resin having good emulsifiability can be obtained. + , Na + , K + Although monovalent metal cations are recommended, Na (sodium) ions are preferred. The ratio of the carboxyl group neutralized with the metal cation, that is, the degree of neutralization, is excellent in the adhesiveness of the coating film and is 40 to 60% in terms of obtaining a good aqueous dispersion. If it is less than 40%, it is difficult to obtain a good aqueous dispersion, and if it exceeds 60%, the adhesion of the coating film is inferior.
[0018]
The glass transition point (hereinafter referred to as Tg) of the ethylene-unsaturated carboxylic acid copolymer neutralized and adjusted to 40 to 60% needs to be 50 to 70 ° C., preferably 50 to 60 ° C. . If the Tg is less than 50 ° C, the scratch resistance as a resin film is reduced, the film is easily broken by press working or the like, and mold galling is likely to occur. If the Tg exceeds 70 ° C, the flexibility of the film is insufficient. It is not preferable because cracks of the film due to processing occur. In the present invention, Tg is measured according to JIS K7121.
[0019]
The amount of the water-dispersible ionomer resin (in terms of solid content) is 40 to 90% by mass, preferably 50 to 80% by mass as a percentage of the total solid content. If this ratio is less than 40% by mass, it becomes difficult to form a uniform film on the metal object, so that the corrosion resistance is significantly lowered. On the other hand, when it exceeds 90% by mass, it becomes difficult to control the film thickness uniformly due to the increase in the viscosity of the treatment liquid. This causes problems such as inferior press workability, as well as deterioration of the appearance of the finished paint and washing of the coating equipment. This is not preferable because it takes time to complete the painting work.
[0020]
On the other hand, the water-soluble epoxy compound used in the present invention is used in order to stably obtain a high level of alkali resistance and secondary adhesion of the coating film during post-coating. Although the percentage with respect to the total solid of a water-soluble epoxy compound is 1-10 mass%, Preferably it is 3-7 mass%. When the blending ratio is less than 1% by mass, the base adhesion of the film and the secondary adhesion of boiling water of a lower postcoat such as a melamine alkyd paint are insufficient. On the other hand, if it exceeds 10% by mass, the coating film becomes excessively hard, and cracks are easily formed or the coating film is easily peeled off by processing.
[0021]
In the above water-soluble epoxy compound, the glycidyl group contained reacts with the carboxyl group of the ionomer resin by heating after coating, improving adhesion to base metal and one-coat / one-bake (1C1B) painted postcoats for home appliances. There is an advantage to make. As the number of functional groups, those having 3 to 4 functional groups are preferable, and examples thereof include pentaerythritol glycidyl ether, glycerol polyglycidyl ether, etc., and the amount of chlorine adjusted to less than 1% by mass. However, in the case of a monofunctional epoxy compound, it is not possible to improve the secondary adhesion function with a lower postcoat such as a melamine alkyd resin paint in a coating film formed from a metal surface treatment agent blended with an ionomer resin. Have difficulty. On the other hand, if the functional group exceeds 5, the crosslink density is too high, the film is hardened, and the workability is remarkably lowered, so that the corrosion resistance may be deteriorated.
[0022]
The viscosity of the water-soluble epoxy compound is preferably 400 mPa · s or less, more preferably 350 mPa · s or less at 25 ° C. from the viewpoint of coating workability. The epoxy equivalent is preferably 6.0 to 7.5 eq / kg, more preferably 6.2 to 7.1 eq / kg from the viewpoint of reactivity.
[0023]
Here, the polyfunctional epoxy compound used conventionally has a large amount of chlorine derived from epichlorohydrin as a raw material. For this reason, the metal surface treatment agent containing a large amount of chlorine has poor storage stability, and precipitates are formed over time, and the film formed with this treatment solution has problems such as poor corrosion resistance. It was.
[0024]
Therefore, in the present invention, a water-soluble polyfunctional epoxy compound having a chlorine content adjusted to less than 1% by mass during production is used. In addition, the amount of chlorine contained in the water-soluble polyfunctional epoxy resin is adjusted to 1% by mass or less, and further, the amount of chlorine contained in the treatment film is adjusted to 0.1% by mass or less, whereby the long-term stability of the treatment agent. In addition, it is possible to improve the corrosion resistance of the surface-treated metal plate obtained by treating this treating agent.
[0025]
The amino group or ammonium ion adsorption type silica used in the present invention is adjusted to pH 9.0 to 10.5 by adsorbing amino groups and / or ammonium ions on the surface of fine particle silica having a particle diameter of 10 to 20 nm. However, colloidal silica dispersed in water is optimal. In adjusting the pH, either an organic amino compound or aqueous ammonia may be used, but the use of an organic amino compound is preferred in terms of workability and working environment. Examples of such organic amino compounds include amino alcohol and diethanolamine.
[0026]
The amount of the silica (in terms of solid content) is 7 to 40% by mass, preferably 15 to 35% by mass as a percentage of the total solid content. If the silica content is less than 7% by mass, the coating will be damaged and the corrosion resistance will decrease. If it exceeds 40% by mass, the coating will become too hard and the flexibility will be reduced. Corrosion resistance also decreases because hair racks and the like are likely to occur.
[0027]
The rust inhibitor used in the present invention is for the purpose of preventing the suppression of external corrosion factors,
(1) Prevention of penetration of corrosion factors,
(2) Excellent adhesion of rust preventive film,
(3) Passivation of the base metal surface by rust prevention ions,
(4) imparting water resistance to the rust preventive film,
It is necessary to satisfy various characteristics such as. Such a rust preventive agent consists of at least 1 sort (s) of a thiocarbonyl compound and ammonium vanadate, and this compounding quantity is 0.1-10 mass%, Preferably it is 1-5 mass%. If this is less than 0.1% by mass, the corrosion resistance of the metal material is not sufficient, and if it exceeds 10% by mass, it will be difficult to form a coating, or even if it is painted, it will continue continuously under the high productivity line. It is difficult to obtain a uniform coating appearance. In addition, when using a thiocarbonyl compound as a rust preventive agent, you may use a phosphate ion together with 0.1 to 10 times the amount of the compounding quantity as a standard. Phosphate ions can be generated from any phosphate compound that produces phosphate ions in aqueous solution. As such a phosphoric acid compound, for example, phosphoric acid, ammonium phosphate, potassium phosphate, sodium phosphate and the like can be used.
[0028]
The thiocarbonyl compound is a thiocarbonyl group (I) shown below.
[0029]
[Chemical 1]
Among them, the thiocarbonyl group (II) having the nitrogen atom and oxygen atom shown below is preferred among them.
[0031]
[Chemical 2]
A compound capable of forming a thiocarbonyl compound in an aqueous solution or in the presence of an acid or alkali can also be used.
Examples of the thiocarbonyl compound include the following formula (III)
[0033]
[Chemical 3]
Thiourea and its derivatives, such as methylthiourea, dimethylthiourea, ethylthiourea, diethylthiourea, diphenylthiourea, thiopental, thiocarbazide, thiocarbazone, thiocyanuric acids, thiohydantoin, 2-thiouramil, 3-thiourazole, Formula (IV)
[0035]
[Formula 4]
For example, thioformamide, thioacetamide, thiopropionamide, thiobenzamide, thiocarbostyril, thiosaccharin, the following formula (V)
[0037]
[Chemical formula 5]
A thioaldehyde compound represented by the formula, for example, thioformaldehyde, thioacetaldehyde, the following formula (VI)
[0039]
[Chemical 6]
[0040]
[Chemical 7]
And other compounds having the structure of the formula (I), such as thiocoumazone, thiocumothiazone, thionine blue J, thiopyrone, thiopyrine, and thiobenzophenone. In addition, what is not melt | dissolved in water among the said thiocarbonyl compounds is once melt | dissolved with an alkaline solution, and is mix | blended in a processing agent.
[0042]
The water-dispersible metal surface treatment agent of the present invention has a water-dispersible olefin resin wax of 0.5 to 20 in terms of the total solid content concentration for the purpose of imparting other functions such as lubricity. A mass% can also be added.
[0043]
Further, the treating agent according to the present invention may further contain other components. Examples thereof include pigments and surfactants. Further, a silane coupling agent may be blended in order to improve the affinity with the resin component, silica particles, and pigment, and further improve the adhesion between the resin component and galvanizing or steel material.
[0044]
Examples of the pigment include inorganic pigments and organic pigments such as titanium oxide, zinc oxide, zirconium oxide, calcium carbonate, barium sulfate, alumina, kaolin clay, carbon black, and iron oxide.
[0045]
Examples of the silane coupling agent include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, and γ-methacryloxy. Examples thereof include propyltriethoxysilane and N- [2- (vinylbenzylamino) ethyl] -3-aminopropyltrimethoxysilane.
[0046]
The water-dispersible metal surface treatment agent of the present invention containing the above components can be used at a total solid content concentration of 10 to 80% by mass. The composition other than the solid content is mostly water, but also includes everything that does not remain in the coating composition after coating and baking, such as a volatile pH adjuster. When the total solid content concentration is less than 10% by mass, the film thickness cannot be sufficiently secured. When the total solid content concentration exceeds 80% by mass, the coating workability is deteriorated, so that it is difficult to ensure a stable coating film thickness.
[0047]
In the preparation method of the water dispersible metal surface treatment agent of the present invention, for example, a predetermined amount of amino group or ammonium ion adsorption type silica is added to an aqueous dispersion of ionomer resin, and water and an alkali component are added to adjust pH. As the alkali component to be added, an aqueous alkali solution such as an organic amino compound or ammonia water is preferable in order to gasify it during the drying process so that no alkali content remains in the solid film. Further, the pH of the treatment agent of the present invention is not limited as long as it is alkaline, but preferably adjusted to about 10 and then added with a predetermined amount of a water-soluble epoxy compound, and at a liquid temperature of 40 ° C. or less for about 10 minutes, Disperse and mix well. In addition, there is a method of heating and melting a mixture of an ionomer resin and a water-soluble epoxy compound and emulsifying all at once, but this method is not preferable particularly when an inorganic rust preventive agent is used together, and a precipitate may be generated. It is better to avoid it.
[0048]
In the treatment method of the present invention, a metal material is treated with the water-dispersible metal surface treatment agent of the present invention and then baked. Although there is no restriction | limiting in particular as a processing method, A roll coater method is preferable and there exist an immersion method, a spray method, etc. in addition. The coating weight is 0.3 to 5.0 g / m in dry mass 2 And 0.3 g / m 2 If it is less than 1, corrosion resistance deteriorates, which is not preferable. Moreover, 5.0 g / m 2 Those exceeding the range are not economically preferable. The baking temperature is preferably 80 to 180 ° C., and the baking time is preferably 2 seconds to 30 minutes, more preferably 4 seconds to 10 minutes.
[0049]
The metal material is not particularly limited, and is applicable to unprocessed steel materials of plate shape or other shapes, electrogalvanized steel materials, hot dip galvanized steel materials, galvalume steel materials, aluminum materials, aluminum alloy materials, and other copper materials. Is possible. Furthermore, the metal material to which the present invention is applied includes a metal-plastic composite material obtained by laminating various metals on a plastic material. Since the surface-treated metal material of the present invention produced in this way is coated with the water-dispersible metal surface treatment agent of the present invention without performing chromate treatment, it is non-polluting, solvent-resistant, scratch-resistant and Excellent post-coating properties.
[0050]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples.
[0051]
(Examples 1-121, Comparative Examples 1-35)
<Preparation of water-dispersible metal surface treatment agent>
100 g of ethylene-methacrylic acid copolymer (melt flow index (MFR) 0.8 g / 10 min at 190 ° C., methacrylic acid content 15% by mass), neutralizer is melted at 250 ° C. and ionomer A resin melt was prepared, 300 g of water was added thereto, and then charged into a pressure-resistant homomixer having an internal volume of 1 liter heated to 170 ° C. with stirring at 1000 rpm for about 2 hours. After completion of the charging, the mixture was further stirred for 1 hour and cooled to room temperature to obtain an ionomer resin aqueous dispersion.
[0052]
Next, pentaerythritol polyglycidyl ether (Denacol EX-1410, manufactured by Nagase Kasei Kogyo Co., Ltd.) having a chlorine content of less than 1.0 mass% and a water solubilization rate of 100% as an epoxy compound, and ammonium ion as a silica surface adsorbs ammonium ions. And colloidal silica controlled to be alkaline, and various blends of ionomer aqueous dispersion resin, epoxy compound and silica in the mass percentages shown in Tables 1 to 4 and Table 8 were added in a disper at 500 rpm for 60 minutes. Stir. In addition, the mass% of the ionomer resin and colloidal silica in Tables 1 to 4 and Table 8 is a value converted to a solid content.
[0053]
During the stirring, the pH was adjusted to 10 with aminoalcohol and stirring was continued for 10 minutes. Then, A: thiourea, B: 1,3-diethyl-2-thiourea, C: thioacetamide as rust preventives , D: 2,2′-ditolylthiourea, E: thiobenzoic acid, F: thioacetaldehyde, G: ammonium vanadate, and ammonium phosphate in various mass percentages as shown in Tables 1 to 4 and Table 8. Further, stirring was continued, and stirring for a total of 60 minutes was completed, followed by filtration with a 200 mesh filter. The filtrate was adjusted with pure water (if necessary), and the water-dispersible metal of this example or comparative example A surface treating agent was used.
[0054]
<Coating on steel plate>
A 2% aqueous solution of a degreasing agent ("Surf Cleaner 155", manufactured by Nippon Paint Co., Ltd.), sprayed at 60 ° C for 60 seconds, washed with water and dried, and then an electrogalvanized steel sheet having a thickness of 1.2 mm (weight per unit area 20 g / m) 2 ), 0.3 to 5.0 g / m of a solid film of the water-dispersible metal surface treatment agent. 2 After coating with a bar coater, the coating film was baked in a gas furnace so that the outlet side plate temperature was 120 ° C. in the in-furnace time of 20 seconds to prepare a test piece. The amount of adhesion was measured by a gravimetric method.
[0055]
<Performance evaluation test>
1) Alkali resistance
Half of the test piece is immersed in a 2% aqueous solution of an alkaline degreasing agent (SC53, manufactured by Nippon Paint Co., Ltd.), and after washing at a liquid temperature of 55 ° C. for 10 minutes, it is washed with water and dried. Comparative observation was made with the immersion part.
◎: No abnormality in coating film, ○: slight discoloration in appearance, △: partial film removal, ×: total film removal
[0056]
2) Whitening resistance (boiling water resistance test of coating film)
After immersing half of the test piece in boiling water of pure water for 2 hours, the test piece was pulled up and waited for natural drying to visually determine the difference in appearance between the immersed part and the non-immersed part.
◎: No difference in appearance, ○: Slightly decolored in the immersion area, △: Partial whitening, ×: Whitening of the entire surface
[0057]
3) Type galling
Uses a cylindrical Eriksen press. The test piece was unoiled and drawn out with a 50 mm diameter cylinder, a drawing ratio of 2.4 mm, a thickness of 1.0 mm, a clearance of 0.0 mm, and a wrinkle pressure of 1.5 tons, and the condition of the cylinder barrel was observed.
◎: No galling, ○: Slight galling, △: Partial galling, ×: Full galling
[0058]
4) Corrosion resistance
A salt spray test based on JIS Z 2371 was conducted. A test piece having an Erichsen 6 mm extruded part and a flat part (end face and back face was a tape seal) was prepared, and the occurrence of white rust was evaluated after 168 hours of salt spray.
◎: No rust, ○: Area ratio 5% or less, △: 5-30%, X: 30% or more
[0059]
5) Postcoat secondary adhesion
The test piece was baked with melamine alkyd resin-based paint (white) under the conditions of a dry film thickness of 20 to 25 μm and 125 ° C. × 20 minutes, immersed in boiling pure water for 30 minutes, left in the room for 24 hours, and then JIS K. In a cross-cut test based on 5400, 100 1-mm square grids were closely marked on the test piece and forcibly peeled in a 45-degree direction with an adhesive tape ("Cello Tape", manufactured by Nichiban Co., Ltd.).
◎: No peeling, ○: Slightly peeling, △: Partial peeling, ×: Whole peeling
[0060]
6) Solvent resistance
Dissolution of the coating after rubbing 8 kg of gauze impregnated with ethanol on the end surface of a SUS round bar with a load of 1 kg × 10 times (reciprocating) and MEK (methyl ethyl ketone) with a load of 1 kg × 50 times (reciprocating) The appearance is dyed with a special dye and judged from the difference in the degree of staining.
◎: No abnormality, ○: Slightly dissolved, △: Partially dissolved, ×: Entirely dissolved (substrate exposed)
[0061]
7) Precipitation of treatment agent
After adding epoxy compounds with different total chlorine content, evaluate the occurrence of precipitation in the treatment agent when aged for 30 days at 40 ° C
◎: No abnormality, ○: Slightly cloudy but no precipitation, △: Increased white turbidity but no precipitation, ×: Large precipitation
[0062]
Tables 1 to 4 and 8 show the composition and evaluation results of the treatment agents.
From these results, it is understood that if the amount of silica in the treating agent is out of the range of the present invention, the corrosion resistance is damaged on the lower limit side and the press workability such as drawing is damaged on the upper limit side, which should be avoided. Further, when the blending amount of the ionomer resin is out of the range of the present invention, damage is large due to corrosion resistance, press-type galling, secondary adhesion of the post coat by melamine alkyd on the lower limit side, and drawing processing etc. on the upper limit side. It turns out that it is not preferable because it is slightly inferior to press working.
[0063]
Moreover, it turns out that the precipitate which generate | occur | produces in a process liquid with respect to time is cloudy or precipitates, when the chlorine content in a water-soluble epoxy compound exceeds 1 mass%. In addition, for water-soluble epoxy compounds with controlled chlorine content, if the amount is outside the scope of the present invention, the secondary adhesion of the postcoat deteriorates on the lower limit side, and alkali resistance, whitening resistance on the upper limit side, It can be seen that the overall level of coating film performance is reduced, such as galling resistance.
[0064]
Further, when the Tg of the ionomer resin is out of the range of the present invention, it can be seen that the film is soft at the lower limit side and the mold galling resistance is inferior, and the film flexibility is insufficient at the upper limit side and the galling resistance is inferior. Regarding the degree of neutralization of the ionomer, it can be seen that when the value falls outside the range of the present invention, the stability of the treatment liquid deteriorates on the lower limit side, and the secondary adhesion of the postcoat deteriorates on the upper limit side. About the adhesion amount of an organic inorganic composite membrane | film | coat, when it remove | deviates from the lower limit range of this invention, it turns out that not only corrosion resistance but mold | die galling resistance and secondary adhesiveness deteriorate.
[0065]
Further, if the amount of the rust inhibitor is outside the range of the present invention, the corrosion resistance is greatly reduced on the lower limit side, and conversely, if it exceeds the upper limit, the damage is large due to mold galling and secondary adhesion of the postcoat.
[0066]
(Examples 122 to 206) (When water-dispersible polyolefin resin is added as an aqueous wax)
Tables 5 to 7 show water-dispersible polyolefin resins (in terms of solid content) having a number average molecular weight of 1500 and a particle size of 0.7 μm in the water-dispersible metal surface treatment agents manufactured for the respective examples and comparative examples described above. Various dispersions at the indicated mass percentage, disperse stirring at 500 rpm for 30 minutes, fine adjustment of pH with amino alcohol in the middle of stirring, filtration through a 200 mesh filter, and water dispersion with a lubrication function added to the filtrate Metal surface treatment agent. These compositions and evaluation results are shown in Tables 5-7.
[0067]
From these results, the addition of the polyolefin resin as a lubricant has almost no effect on other performances within the scope of the present invention, and the effect of the ionomer resin and silica constituting the treatment agent is the same as before the addition of the polyolefin resin. It turns out that it is an effect.
[0068]
[Table 1]
[Table 2]
[Table 3]
[Table 4]
[Table 5]
[Table 6]
[Table 7]
[Table 8]
【The invention's effect】
Since the water-dispersible metal surface treatment agent of the present invention is prepared by combining a specific ionomer resin, a water-soluble epoxy compound, silica and a non-chromium rust preventive agent, it has a high storage stability at 40 ° C. or less for 1 month or more. Have sex. In addition, the surface-treated metal material of the present invention such as a post-plating product is not resistant to alkali resistance, paint adhesion, and corrosion resistance, but has solvent resistance, scratch resistance, mold galling, deep drawing workability, and post coatability. Satisfy etc. Furthermore, since the treatment agent and the surface-treated metal material of the present invention do not contain chromium, they are low pollution. Thus, the surface-treated metal material of the present invention, which is excellent in corrosion resistance and low pollution, is suitable as a constituent member for household electrical products, building materials, automobile parts and the like.
Claims (5)
Priority Applications (1)
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| JP2001260020A JP3801470B2 (en) | 2001-08-29 | 2001-08-29 | Rust preventive containing water dispersible metal surface treatment agent, surface treatment metal material and method for producing the same |
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| JP2001260020A JP3801470B2 (en) | 2001-08-29 | 2001-08-29 | Rust preventive containing water dispersible metal surface treatment agent, surface treatment metal material and method for producing the same |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7816458B2 (en) | 2005-11-22 | 2010-10-19 | E. I. Du Pont De Nemours And Company | Aqueous dispersions containing ionomer resins and rust-preventive ionomeric coatings made therefrom |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4901116B2 (en) * | 2004-03-04 | 2012-03-21 | 新日本製鐵株式会社 | Surface-treated metal plate |
| BRPI0519374A2 (en) * | 2004-12-23 | 2009-01-20 | Posco Eng & Constr Co Ltd | chromium free composition for surface treatment and surface treated sheet metal |
| WO2006079643A1 (en) | 2005-01-28 | 2006-08-03 | Basf Aktiengesellschaft | Anti-corrosion coatings containing thioamide groups |
| US8273412B2 (en) | 2005-01-28 | 2012-09-25 | Basf Aktiengesellschaft | Method for applying corrosion protection layers comprising thioamides to metallic surfaces |
| US20060233955A1 (en) | 2005-04-14 | 2006-10-19 | Noel Smith | Process for the coating of metallic components with an aqueous organic composition |
| JP5311756B2 (en) * | 2007-03-26 | 2013-10-09 | 株式会社神戸製鋼所 | Electrical Zn-plated steel sheet with excellent stain resistance |
| CN102414020B (en) | 2009-05-11 | 2016-04-20 | 新日铁住金株式会社 | Surface-treated metal material and manufacture method thereof |
| JP5185911B2 (en) * | 2009-10-28 | 2013-04-17 | 株式会社神戸製鋼所 | Resin coated metal plate |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US7816458B2 (en) | 2005-11-22 | 2010-10-19 | E. I. Du Pont De Nemours And Company | Aqueous dispersions containing ionomer resins and rust-preventive ionomeric coatings made therefrom |
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