JP3930708B2 - Surface treatment method of aluminum material and surface-treated aluminum material - Google Patents
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Description
【０００１】
【発明の属する技術分野】
この発明は、アルミニウム又はアルミニウム合金からなる押出材や圧延材等のアルミニウム材の表面の金属光沢を均一に制御し、仕上り外観に斑のない均一な落ち着いた表面状態を有する表面処理アルミニウム材を製造するためのアルミニウム材の表面処理方法、及びこの方法によって作製された表面処理アルミニウム材に関する。
【０００２】
【従来の技術】
アルミニウム材は、軽量で耐蝕性や耐久性、加工性、表面処理性等に優れており、また、適度な強度を有することから、外装材、内装材、表層材等の建築材料や電気機器等のケーシング材料を始めとして、極めて多くの分野で広範に使用されている。
【０００３】
そして、このようなアルミニウム材については、その使用目的に応じて周囲の環境との調和や意匠性等の向上を図る目的で、梨地処理、ブラスト処理等の方法で表面光沢を調整したり、あるいは、電解着色処理、塗装処理等の方法で着色する表面処理が行われている。
【０００４】
この種の表面処理の具体例としては、例えば、Ｆｅ、Ｍｎ、Ｚｒ、Ｓｉ、Ｃｒ、Ｍｇ、Ｚｎ、Ｃｕ等の合金成分の添加量を調整し、粗面化処理で表面色調を白色に調整した後に陽極酸化処理を施して色調が白色のアルミニウム材を得る方法（特開平3-47,937号公報）、熱処理とエッチング処理を施して結晶粒を粗大化させ、結晶模様を有するアルミニウム材を得る方法（特開平3-257,177号公報）、完全軟化焼鈍処理を施した後に塑性変形を加え、次いで熱処理を施して結晶粒を粗大化させ、結晶模様を有するアルミニウム材を得る方法（特開平5-70,906号公報）、Ｆｅ成分とＣｕ成分とを所定の割合で含むＡｌ−Ｍｇ−Ｓｉ系合金を押出加工し、次いでエッチング処理して結晶模様を有するアルミニウム材を得る方法（特開平6-336,682号公報）等が提案されている。
【０００５】
しかしながら、このような従来の表面処理では、アルミニウム材の表面に付与される表面光沢の選択の幅が狭く、観察角度によって色調が異なる角度依存性があり、また、処理後の外観を制御できないために表面光沢や色調において均一性や再現性に乏しく、更に、特に建築材料等の分野で嗜好の多様化に伴って要求される広範でバラエティに富む表面光沢や色調、特に手で触れてもザラザラした感じはないが金属光沢感が少なくて目にやさしいザラザラ感を有する表面光沢や色調に対応できないという問題があった。
【０００６】
【発明が解決しようとする課題】
そこで、本発明者らは、このような問題を解決すべく鋭意検討した結果、多塩基酸及び／又はその塩を含む水溶液中での陽極酸化処理に続いて、一塩基酸を含む水溶液中でのアノード電解処理を行い、更に引き続いて塩酸水溶液中での塩酸浸漬処理を行い、更にアルカリ性水溶液中に浸漬してアルカリ処理を行うことにより、表面光沢や色調において均一性や再現性に富み、広範囲に亘って制御された表面光沢や色調（目にやさしいザラザラ感）を付与することができ、同時に圧延痕や押出痕等も消失することを見出し、本発明を完成した。
【０００７】
従って、本発明の目的は、素材形成時の圧延痕や押出痕等が消失すると共に、表面光沢や色調において均一性や再現性に富み、広範囲に亘って制御された表面光沢や色調を付与することができるアルミニウム材の表面処理方法を提供することにある。
【０００８】
【課題を解決するための手段】
すなわち、本発明は、アルミニウム又はアルミニウム合金からなる建築材又はケーシング材用のアルミニウム材の表面処理方法であり、多塩基酸及び／又はその塩を含む水溶液中で陽極酸化してアルミニウム材の表面に膜厚０．０１〜１０μ m の陽極酸化皮膜を形成せしめる第一工程と、一塩基酸を含む水溶液中でアノード電解を行う第二工程と、塩酸水溶液中に浸漬する塩酸浸漬処理を行う第三工程と、アルカリ性水溶液中に浸漬してアルカリ処理を行なう第四工程とを含み、アルミニウム材の表面光沢及び／又は色調を制御することを特徴とするアルミニウム材の表面処理方法である。
【０００９】
また、本発明は、第三工程の塩酸浸漬処理の後に、第四工程としてアルカリ性水溶液中に浸漬するアルカリ処理を行うアルミニウム材の表面処理方法である。
【００１０】
本発明において、アルミニウム材の表面に陽極酸化皮膜を形成せしめる第一工程の陽極酸化処理において使用される多塩基酸及び／又はその塩としては、例えば、ホウ酸、リン酸、硫酸、シュウ酸、酒石酸等の多塩基酸や、そのアンモニウム、ナトリウム（Na）、カリウム（Ｋ）等の塩を挙げることができる。これらはその１種のみを単独で用いることができるほか、２種以上を混合して得られた混酸及びその塩として用いることもできる。
【００１１】
そして、このような多塩基酸及び／又はその塩を含む水溶液としては、例えば、四ホウ酸ナトリウム-ホウ酸浴、ホウ酸アンモニウム浴、リン酸アンモニウム浴等の中性浴や、硫酸、リン酸、シュウ酸、酒石酸等の酸性浴を挙げることができ、中性浴を用いる場合には、形成される陽極酸化皮膜が障壁型皮膜を形成しているので、その膜厚を実用上０．０１〜１μｍの範囲とするのがよく、また、酸性浴を用いる場合には、形成される陽極酸化皮膜が多孔質皮膜を形成しているので、その膜厚を実用上０．０１〜１０μｍの範囲とするのがよい。この陽極酸化皮膜の膜厚が不足すると凹凸の均一性が低下し、反対に、必要以上に厚くしても効果の向上が認められず、時間及び電力の点で経済的でない。
【００１２】
この第一工程の陽極酸化処理における処理条件については、中性浴を用いるか又は酸性浴を用いるか、形成される陽極酸化皮膜の膜厚をどの程度に設計するか等によって異なるが、例えば、中性浴の場合には、浴濃度１〜３００ｇ／リットル、ｐＨ４〜１０、浴温度０〜８０℃、定電流（電流密度）１〜１００Ａ／ｍ2、最終電圧１０〜１０００Ｖ（好ましくは１０〜５００Ｖ）であり、また、酸性浴の場合には、浴濃度１〜３００ｇ／リットル、浴温度０〜５０℃、定電流（電流密度）５〜３００Ａ／ｍ2又は定電圧５〜１５０Ｖ、時間５〜３６００秒である。
【００１３】
また、本発明において、上記陽極酸化処理に続いて行われる第二工程の電解処理は、一塩基酸を含む水溶液中でアノード電解により行われ、この際に用いられる一塩基酸としては、塩酸、硝酸、酢酸、過塩素酸等の一塩基酸が挙げられ、好ましくは塩酸、硝酸等である。これらの一塩基酸は、その１種のみを単独で用いてもよいほか、２種以上を混合して得られた混酸を用いてもよく、更にこの際に、その塩を一部添加してもよい。この電解処理により、陽極酸化処理によりアルミニウム材の表面に形成された陽極酸化皮膜を破壊し、このアルミニウム材の表面に極めて微細な凹凸が形成される。
【００１４】
この第二工程の電解処理における処理条件については、使用する一塩基酸の種類によっても異なるが、通常、１〜５００ｇ／リットル、好ましくは１０〜２００ｇ／リットルの濃度の処理液を用い、液温度１０〜６０℃、好ましくは２０〜５０℃の範囲で、アルミニウム材を陽極として電流密度０．１〜３Ａ／ｄｍ2、好ましくは０．５〜２．５Ａ／ｄｍ2の直流、商用交流、矩形波交流、パルス波形等の電流を２〜３００秒間、好ましくは３〜１８０秒間通電し、アノード電解を行う。
【００１５】
更に、本発明方法においては、上記第二工程の電解処理に引き続いて、第三工程として塩酸水溶液中に浸漬する塩酸浸漬処理を行う。
この塩酸浸漬処理は、アルミニウム材を塩酸水溶液中に浸漬することにより行われる。この塩酸浸漬処理の処理条件については、塩酸濃度が１０〜２００ｇ／リットル、好ましくは３０〜１５０ｇ／リットルであり、また、処理温度が２０〜５０℃、好ましくは２５〜４０℃であり、更に、処理時間が２０分以下、好ましくは３〜１５分である。この塩酸水溶液による塩酸浸漬処理は、塩酸濃度１０ｇ／リットル以上、処理温度２０℃以上で進行し、反対に、塩酸濃度が２００ｇ／リットルより高くなったり、あるいは、処理温度が５０℃より高くなると、化学溶解反応が激しくなって微細な凹凸の抑制が難しくなり、また、処理時間が２０分を超えると均一溶解が過度に進行してかえって凹凸が目立たなくなるほか、アルミの溶解減量も大きくなって好ましくない。
【００１６】
また、この塩酸浸漬処理においては、微細な凹凸の制御を容易にするために、使用する塩酸水溶液中に、Ｆｅイオン、Ｎｉイオン、Ｃｕイオン、ＳＯ4イオン、ＮＯ3イオン、ＰＯ4イオン等から選ばれた1種又は２種以上のイオンを添加してもよく、具体的には、例えば硫酸塩、硝酸塩、塩化物、リン酸塩等の形で添加され、また、シュウ酸等の有機酸を添加してもよく、その添加量は、通常０〜５ｇ／リットル、好ましくは０〜１ｇ／リットルの範囲である。
【００１７】
そして、本発明においては、上記第三工程の塩酸浸漬処理に引き続いて、第四工程としてアルカリ性水溶液中に浸漬するアルカリ処理を行ってもよい。
この第四工程のアルカリ処理における処理条件については、遊離アルカリ濃度が２０〜１００ｇ／リットル、好ましくは４０〜７０ｇ／リットルであり、処理温度が３０〜７０℃、好ましくは４０〜６０℃であり、また、ｐＨ値が１３以上であり、更に、処理時間が３〜２０分、好ましくは５〜１５分である。遊離アルカリ濃度２０ｇ／リットル未満、処理温度３０℃未満、又はｐＨ値１３未満では、いずれの場合も、溶解速度が遅く、生産性が低下する。反対に、遊離アルカリ濃度１００ｇ／リットル超、又は処理温度７０℃超では、溶解速度が速くなりすぎて制御困難になり、表面がなだらかになってしまい、所望の表面状態を得るのが困難になる。また、処理時間についても、遊離アルカリ濃度、処理温度、ｐＨ値等の条件によっても異なるが、３分に達しない短時間浸漬では均一溶解が進行せずに所望の凹凸を得ることが難しく、また、２０分を超える長時間浸漬では均一溶解が過度に進行してかえって凹凸が目立たなくなるほか、アルミの溶解減量も大きくなって好ましくない。
【００１８】
更に必要により、上記第四工程のアルカリ処理の後に、スマット除去処理、陽極酸化処理、染色又は金属の電解析出による着色処理、あるいは封孔処理を行ってもよく、また、これらの処理に代えて、クロメート処理を行ってもよい。これらの陽極酸化処理、着色処理、封孔処理、及びクロメート処理については、従来公知の方法で実施することができる。
【００１９】
また、本発明においては、第一工程の陽極酸化処理に先駆けて、アルミニウム材の前処理として、脱脂処理及び／又はアルカリエッチング処理を行ってもよい。また、アルカリエッチング処理の後に必要に応じてスマット除去処理を行ってもよい。これらの脱脂処理、アルカリエッチング処理及びスマット除去処理についても、従来公知の方法で実施することができる。
【００２０】
本発明によれば、上記陽極酸化処理によりアルミニウム材の表面に所定の膜厚の陽極酸化皮膜を形成せしめ、次いで電解処理を行うことによりこの陽極酸化皮膜を破壊し、アルミニウム材の素地の金属組織に影響されること無く、このアルミニウム材の表面に均一かつ微細で大きさの揃った孔を形成せしめることができる。
【００２１】
また、上記陽極酸化処理後の電解処理に続いて塩酸浸漬処理を行うと、電解処理の皮膜破壊によって形成された孔の部分でのみアルミニウム材の素地と塩酸とを反応させてエッチピットを形成することができ、その後にアルカリ処理を行った場合には、アルミニウム材の素地の金属組織に影響されること無く、均一に凹凸を存在させることができる。
【００２２】
【発明の実施の形態】
以下、実施例に基づいて、本発明の好適な実施の形態を具体的に説明する。
〔実施例１〕
JIS A6063アルミニウム合金押出形材を、前処理として、濃度５０ｇ／リットル、浴温５０℃の水酸化ナトリウム水溶液に５分間浸漬し、このアルミニウム合金押出形材の表面の自然酸化皮膜を除去した。
【００２３】
次に、前処理済みのアルミニウム合金押出形材を、濃度５０ｇ／リットルのホウ酸アンモニウム水溶液中、浴温３０℃及び電流密度１０Ａ／ｍ2、最終電圧８０Ｖの条件で陽極酸化し（第一工程）、次いで濃度１００ｇ／リットルの塩酸水溶液中、浴温２０℃、電流密度１００Ａ／ｍ2、及び処理時間６０秒の条件でアノード電解して多数の微細なピットを形成せしめ（第二工程）、更に、濃度１００ｇ／リットルの塩酸水溶液中、浴温３０℃及び処理時間１２０秒の条件で浸漬して第二工程で形成されたピットを拡大させ（第三工程）、また、濃度５０ｇ／リットルの水酸化ナトリウム水溶液中、浴温５０℃及び処理時間１０分の条件で浸漬して上記塩酸浸漬処理で形成されたピットを更に拡大させ（第四工程）、表面処理されたアルミニウム合金押出形材を得た。
【００２４】
得られた表面処理アルミニウム合金押出形材の光沢度及び表面粗さ（Ra）を、試料内の測定位置を変えて１０点測定し、その平均値、及び最大値と最小値との差を求めた。この実施例１の表面処理アルミニウム合金押出形材は、その光沢度及び表面粗さにおいてばらつきがなく、手で触れてもザラザラした感触はないが、金属光沢感が無くて目にやさしいザラザラ感のある均一な外観であった。また、押出痕が消失し、表面欠陥（ストレインマークやストリーク等）が無く、表面品質が安定していた。
結果を表１に示す。
【００２５】
〔実施例２〕
実施例１と同様にして自然酸化皮膜を除去した前処理済みのアルミニウム合金押出形材を、濃度１００ｇ／リットルのリン酸水溶液中、浴温２０℃及び電流密度３０Ａ／ｍ2、処理時間６００秒の条件で陽極酸化し（第一工程）、次いで濃度１００ｇ／リットルの塩酸水溶液中、浴温２０℃及び処理時間６０秒の条件でアノード電解して多数の微細なピットを形成せしめ（第二工程）、更に、濃度５５ｇ／リットルの塩酸水溶液中、浴温３５℃及び処理時間１２０秒の条件で浸漬して第二工程で形成されたピットを拡大させ（第三工程）、また、濃度５０ｇ／リットルの水酸化ナトリウム水溶液中、浴温５０℃及び処理時間１０分の条件で浸漬して上記塩酸浸漬処理で形成されたピットを更に拡大させ（第四工程）、表面処理されたアルミニウム合金押出形材を得た。
【００２６】
得られた表面処理アルミニウム合金押出形材の光沢度及び表面粗さ（Ra）を実施例１と同様にして測定し、その平均値、及び最大値と最小値との差を求めた。この実施例２の表面処理アルミニウム合金押出形材は、実施例１と同様に、その光沢度及び表面粗さにおいてばらつきがなく、押出痕や表面欠陥が無くて均一な外観であった。
結果を表１に示す。
【００２７】
〔実施例３〕
第一工程の陽極酸化処理で用いた処理浴を濃度１５０ｇ／リットルの硫酸水溶液とした以外は、上記実施例２と同様にして表面処理を行い、得られた表面処理アルミニウム合金押出形材の光沢度及び表面粗さ（Ra）を上記実施例１と同様にして測定し、その平均値、及び最大値と最小値との差を求めた。この実施例３の表面処理アルミニウム合金押出形材は、実施例２と同様に、その光沢度及び表面粗さにおいてばらつきがなく、押出痕や表面欠陥が無くて均一な外観であった。
結果を表１に示す。
【００２８】
〔実施例４〕
第一工程の陽極酸化処理で用いた処理浴を濃度４０ｇ／リットルのシュウ酸水溶液とした以外は、上記実施例２と同様にして表面処理を行い、得られた表面処理アルミニウム合金押出形材の光沢度及び表面粗さ（Ra）を上記実施例１と同様にして測定し、その平均値、及び最大値と最小値との差を求めた。この実施例４の表面処理アルミニウム合金押出形材は、実施例２と同様に、その光沢度及び表面粗さにおいてばらつきがなく、押出痕や表面欠陥が無くて均一な外観であった。
結果を表１に示す。
【００２９】
〔実施例５〕
第一工程の陽極酸化処理で用いた処理浴を濃度１０ｇ／リットルの酒石酸水溶液とした以外は、上記実施例２と同様にして表面処理を行い、得られた表面処理アルミニウム合金押出形材の光沢度及び表面粗さ（Ra）を上記実施例１と同様にして測定し、その平均値、及び最大値と最小値との差を求めた。この実施例５の表面処理アルミニウム合金押出形材は、実施例２と同様に、その光沢度及び表面粗さにおいてばらつきがなく、押出痕や表面欠陥が無くて均一な外観であった。
結果を表１に示す。
【００３０】
〔比較例１〕
前処理として、濃度５０ｇ／リットル、浴温５０℃の水酸化ナトリウム水溶液に５分間浸漬し、このアルミニウム合金押出形材の表面の自然酸化皮膜を除去した後、濃度５５ｇ／リットルの塩酸水溶液中、浴温３５℃及び処理時間５分間の条件で浸漬し、次いで濃度５０ｇ／リットルの水酸化ナトリウム水溶液中、浴温５０℃及び処理時間１０分の条件で浸漬し、表面処理されたアルミニウム合金押出形材を得た。
【００３１】
得られた表面処理アルミニウム合金押出形材の光沢度及び表面粗さ（Ra）を上記実施例１と同様にして測定し、その平均値、及び最大値と最小値との差を求めた。この比較例１の表面処理アルミニウム合金押出形材は、凹凸の分布に偏りがあり、ムラのある表面状態であることが確認された。
結果を表１に示す。
【００３２】
【表１】
【発明の効果】
本発明のアルミニウム材の表面処理方法によれば、素材形成時の圧延痕や押出痕等が消失すると共に、表面光沢や色調において均一性や再現性に富み、広範囲に亘って制御された表面光沢や色調を付与することができる。[0001]
BACKGROUND OF THE INVENTION
This invention manufactures a surface-treated aluminum material having a uniform and calm surface state with no unevenness in the finished appearance by uniformly controlling the metallic luster of the surface of the aluminum material such as extruded material or rolled material made of aluminum or aluminum alloy. TECHNICAL FIELD The present invention relates to a surface treatment method for an aluminum material and a surface-treated aluminum material produced by this method.
[0002]
[Prior art]
Aluminum materials are lightweight, excellent in corrosion resistance, durability, workability, surface treatment properties, etc., and because they have moderate strength, building materials such as exterior materials, interior materials, surface layer materials, electrical equipment, etc. It is widely used in many fields including casing materials.
[0003]
And for such an aluminum material, the surface gloss is adjusted by a method such as a satin treatment or a blast treatment for the purpose of improving the harmony with the surrounding environment or improving the design depending on the purpose of use, or Surface treatment for coloring by a method such as electrolytic coloring treatment or coating treatment is performed.
[0004]
Specific examples of this type of surface treatment include, for example, adjusting the additive amount of alloy components such as Fe, Mn, Zr, Si, Cr, Mg, Zn, and Cu, and adjusting the surface color tone to white by roughening treatment. And then anodizing to obtain an aluminum material having a white color tone (Japanese Patent Laid-Open No. 3-47,937), and a method of obtaining an aluminum material having a crystal pattern by coarsening crystal grains by heat treatment and etching treatment (Japanese Patent Laid-Open No. 3-257,177), a method of obtaining an aluminum material having a crystal pattern by applying plastic deformation after a complete softening annealing treatment and then subjecting to heat treatment to coarsen crystal grains (Japanese Patent Laid-Open No. 5-70,906) No. 6), a method for obtaining an aluminum material having a crystal pattern by extruding an Al—Mg—Si based alloy containing a Fe component and a Cu component in a predetermined ratio, and then performing an etching process (JP-A-6-336,682). ) Etc. Has been.
[0005]
However, in such a conventional surface treatment, the range of selection of the surface gloss imparted to the surface of the aluminum material is narrow, the color tone varies depending on the observation angle, and the appearance after the treatment cannot be controlled. In addition, the surface gloss and color tone are poor in uniformity and reproducibility, and furthermore, the surface gloss and color tone that has a wide variety that is required in accordance with the diversification of tastes especially in the field of building materials etc. However, there was a problem that it was not possible to cope with surface gloss and color tone that had a feeling of roughness that was easy on the eyes and had a metallic gloss feeling.
[0006]
[Problems to be solved by the invention]
Accordingly, as a result of intensive studies to solve such problems, the present inventors have conducted an anodization treatment in an aqueous solution containing a polybasic acid and / or a salt thereof, followed by an aqueous solution containing a monobasic acid. By performing an anodic electrolysis treatment, followed by a hydrochloric acid immersion treatment in an aqueous hydrochloric acid solution , and further carrying out an alkali treatment by immersion in an alkaline aqueous solution , the surface gloss and color tone are excellent in uniformity and reproducibility, and a wide range. It was found that a controlled surface gloss and color tone (grainy feeling that is easy on the eyes) can be imparted, and at the same time, rolling traces and extrusion traces disappeared, and the present invention was completed.
[0007]
Accordingly, the object of the present invention is to eliminate rolling marks and extrusion marks at the time of forming the material, and to provide surface gloss and color tone controlled over a wide range with excellent uniformity and reproducibility in surface gloss and color tone. An object of the present invention is to provide a surface treatment method for an aluminum material.
[0008]
[Means for Solving the Problems]
That is, the present invention is a surface treatment method of an aluminum material for a building material or casing material made of aluminum or an aluminum alloy, and is anodized in an aqueous solution containing a polybasic acid and / or a salt thereof on the surface of the aluminum material. A first step of forming an anodic oxide film having a film thickness of 0.01 to 10 μm , a second step of performing an anodic electrolysis in an aqueous solution containing a monobasic acid, and a third step of performing a hydrochloric acid dipping treatment of immersing in an aqueous hydrochloric acid solution It is a surface treatment method for an aluminum material, comprising a step and a fourth step of performing an alkali treatment by dipping in an alkaline aqueous solution, and controlling the surface gloss and / or color tone of the aluminum material.
[0009]
Moreover, this invention is a surface treatment method of the aluminum material which performs the alkali treatment immersed in alkaline aqueous solution as a 4th process after the hydrochloric acid immersion process of a 3rd process.
[0010]
In the present invention, for example, boric acid, phosphoric acid, sulfuric acid, oxalic acid, polybasic acid and / or salt thereof used in the first step anodizing treatment for forming an anodized film on the surface of the aluminum material, Examples thereof include polybasic acids such as tartaric acid and salts thereof such as ammonium, sodium (Na) and potassium (K). These can be used alone, or can be used as a mixed acid obtained by mixing two or more and salts thereof.
[0011]
Examples of the aqueous solution containing such a polybasic acid and / or salt thereof include neutral baths such as sodium tetraborate-borate bath, ammonium borate bath, ammonium phosphate bath, sulfuric acid, phosphoric acid, and the like. An acidic bath such as oxalic acid and tartaric acid can be used. When a neutral bath is used, the formed anodic oxide film forms a barrier-type film. It is good to make it in a range of ˜1 μm, and when an acidic bath is used, since the formed anodized film forms a porous film, the film thickness is practically in the range of 0.01 to 10 μm. It is good to do. If the film thickness of this anodic oxide film is insufficient, the uniformity of the unevenness is lowered, and conversely, even if it is thicker than necessary, the improvement of the effect is not recognized, and it is not economical in terms of time and power.
[0012]
The treatment conditions in the first step anodizing treatment vary depending on whether a neutral bath or an acidic bath is used, how much the thickness of the formed anodized film is designed, etc. In the case of a neutral bath, the bath concentration is 1 to 300 g / liter, pH 4 to 10, bath temperature 0 to 80 ° C., constant current (current density) 1 to 100 A / m 2 , final voltage 10 to 1000 V (preferably 10 to 10 V). In the case of an acidic bath, the bath concentration is 1 to 300 g / liter, the bath temperature is 0 to 50 ° C., the constant current (current density) is 5 to 300 A / m 2, or the constant voltage is 5 to 150 V, and the time is 5 ~ 3600 seconds.
[0013]
In the present invention, the electrolytic treatment of the second step performed after the anodizing treatment is performed by anodic electrolysis in an aqueous solution containing a monobasic acid . Examples of the monobasic acid used at this time include hydrochloric acid, Examples thereof include monobasic acids such as nitric acid, acetic acid and perchloric acid, preferably hydrochloric acid and nitric acid. As these monobasic acids , only one of them may be used alone, or a mixed acid obtained by mixing two or more of them may be used. In this case, a part of the salt is added. Also good. By this electrolytic treatment, the anodized film formed on the surface of the aluminum material by the anodic oxidation treatment is destroyed, and extremely fine irregularities are formed on the surface of the aluminum material.
[0014]
The treatment conditions in the electrolytic treatment of the second step vary depending on the type of monobasic acid to be used, but usually use a treatment liquid having a concentration of 1 to 500 g / liter, preferably 10 to 200 g / liter, and the liquid temperature. DC, commercial alternating current, rectangular wave alternating current with current density of 0.1 to 3 A / dm 2, preferably 0.5 to 2.5 A / dm 2 in the range of 10 to 60 ° C., preferably 20 to 50 ° C. with aluminum material as the anode The anode electrolysis is performed by applying a current such as a pulse waveform for 2 to 300 seconds, preferably 3 to 180 seconds.
[0015]
Furthermore, in the method of the present invention, subsequent to the electrolytic treatment in the second step, a hydrochloric acid immersion treatment in which the substrate is immersed in a hydrochloric acid aqueous solution is performed as a third step.
This hydrochloric acid immersion treatment is performed by immersing an aluminum material in an aqueous hydrochloric acid solution. Regarding the treatment conditions of this hydrochloric acid immersion treatment, the hydrochloric acid concentration is 10 to 200 g / liter, preferably 30 to 150 g / liter, the treatment temperature is 20 to 50 ° C., preferably 25 to 40 ° C., The treatment time is 20 minutes or less, preferably 3 to 15 minutes. The hydrochloric acid immersion treatment with this hydrochloric acid aqueous solution proceeds at a hydrochloric acid concentration of 10 g / liter or more and a treatment temperature of 20 ° C. or more. On the contrary, when the hydrochloric acid concentration is higher than 200 g / liter or the treatment temperature is higher than 50 ° C., The chemical dissolution reaction becomes violent and it becomes difficult to suppress fine irregularities, and when the treatment time exceeds 20 minutes, the uniform dissolution progresses excessively, and the irregularities become inconspicuous, and the dissolution loss of aluminum is also increased. Absent.
[0016]
Further, in this hydrochloric acid immersion treatment, in order to facilitate the control of fine irregularities, the aqueous hydrochloric acid solution used contains Fe ions, Ni ions, Cu ions, SO 4 ions, NO 3 ions, PO 4 ions, etc. One or more selected ions may be added. Specifically, for example, sulfate, nitrate, chloride, phosphate, etc. are added, and organic acids such as oxalic acid are added. May be added, and the addition amount is usually in the range of 0 to 5 g / liter, preferably 0 to 1 g / liter.
[0017]
And in this invention, you may perform the alkali process immersed in alkaline aqueous solution as a 4th process following the hydrochloric acid immersion process of the said 3rd process.
Regarding the treatment conditions in the alkali treatment of the fourth step, the free alkali concentration is 20 to 100 g / liter, preferably 40 to 70 g / liter, the treatment temperature is 30 to 70 ° C., preferably 40 to 60 ° C., Moreover, pH value is 13 or more, Furthermore, processing time is 3 to 20 minutes, Preferably it is 5 to 15 minutes. When the free alkali concentration is less than 20 g / liter, the treatment temperature is less than 30 ° C., or the pH value is less than 13, in any case, the dissolution rate is slow and the productivity is lowered. On the other hand, when the free alkali concentration exceeds 100 g / liter, or the processing temperature exceeds 70 ° C., the dissolution rate becomes too fast and difficult to control, the surface becomes smooth, and it becomes difficult to obtain a desired surface state. . Also, the treatment time varies depending on conditions such as free alkali concentration, treatment temperature, pH value, etc., but it is difficult to obtain desired irregularities without uniform dissolution in short-time immersion that does not reach 3 minutes, In the case of soaking for more than 20 minutes, uniform dissolution proceeds excessively, and the unevenness becomes inconspicuous, and the dissolution loss of aluminum becomes large.
[0018]
Furthermore, if necessary, after the alkali treatment in the fourth step, smut removal treatment, anodization treatment, coloring treatment by dyeing or electrolytic deposition of metal, or sealing treatment may be performed, or instead of these treatments. Then, chromate treatment may be performed. These anodizing treatment, coloring treatment, sealing treatment, and chromate treatment can be carried out by a conventionally known method.
[0019]
Moreover, in this invention, you may perform a degreasing process and / or an alkali etching process as a pre-process of an aluminum material prior to the anodizing process of a 1st process. Moreover, you may perform a smut removal process as needed after an alkali etching process. These degreasing treatments, alkali etching treatments and smut removal treatments can also be carried out by conventionally known methods.
[0020]
According to the present invention, an anodic oxidation film having a predetermined film thickness is formed on the surface of the aluminum material by the anodization treatment, and then the anodization film is destroyed by performing an electrolytic treatment. It is possible to form uniform, fine, and uniform holes on the surface of the aluminum material without being affected by the above.
[0021]
Further, when the hydrochloric acid immersion treatment is performed following the electrolytic treatment after the anodizing treatment, an etch pit is formed by reacting the base material of the aluminum material and hydrochloric acid only at the hole portion formed by the film destruction of the electrolytic treatment. When the alkali treatment is performed after that, the unevenness can be made to exist uniformly without being affected by the metal structure of the base material of the aluminum material.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be specifically described based on examples.
[Example 1]
As a pretreatment, JIS A6063 aluminum alloy extruded profile was immersed in an aqueous sodium hydroxide solution having a concentration of 50 g / liter and a bath temperature of 50 ° C. to remove the natural oxide film on the surface of the aluminum alloy extruded profile.
[0023]
Next, the pretreated aluminum alloy extruded shape is anodized in an aqueous solution of ammonium borate having a concentration of 50 g / liter under conditions of a bath temperature of 30 ° C., a current density of 10 A / m 2 , and a final voltage of 80 V (first step). ) And then anode electrolysis in an aqueous hydrochloric acid solution having a concentration of 100 g / liter, bath temperature of 20 ° C., current density of 100 A / m 2 , and treatment time of 60 seconds to form many fine pits (second step), Furthermore, the pits formed in the second step were expanded by immersion in a hydrochloric acid aqueous solution having a concentration of 100 g / liter at a bath temperature of 30 ° C. and a treatment time of 120 seconds (third step). The surface-treated aluminium is further expanded by immersing it in a sodium hydroxide aqueous solution under conditions of a bath temperature of 50 ° C. and a treatment time of 10 minutes (fourth step). To obtain a beam alloy extruded shapes.
[0024]
Glossiness and surface roughness (Ra) of the obtained surface-treated aluminum alloy extruded shape are measured at 10 points by changing the measurement position in the sample, and the average value and the difference between the maximum value and the minimum value are obtained. It was. The surface-treated aluminum alloy extruded profile of Example 1 has no variation in glossiness and surface roughness, and does not feel rough even when touched by hand, but has no metallic luster and has a rough feel that is gentle to the eyes. It had a uniform appearance. Also, the extrusion marks disappeared, there were no surface defects (strain marks, streaks, etc.), and the surface quality was stable.
The results are shown in Table 1.
[0025]
[Example 2]
A pretreated aluminum alloy extruded shape from which a natural oxide film was removed in the same manner as in Example 1 was used in an aqueous phosphoric acid solution having a concentration of 100 g / liter, a bath temperature of 20 ° C., a current density of 30 A / m 2 , and a treatment time of 600 seconds. Then, anodization was performed in an aqueous hydrochloric acid solution having a concentration of 100 g / l in a condition of a bath temperature of 20 ° C. and a treatment time of 60 seconds to form a large number of fine pits (second process). ) Further, the pit formed in the second step was expanded by immersion in a 55 g / liter hydrochloric acid aqueous solution at a bath temperature of 35 ° C. and a treatment time of 120 seconds (third step). The surface treated aluminum is further expanded by immersing in a liter of sodium hydroxide aqueous solution under the conditions of a bath temperature of 50 ° C. and a treatment time of 10 minutes (fourth step). To obtain a beam alloy extruded shapes.
[0026]
The glossiness and surface roughness (Ra) of the obtained surface-treated aluminum alloy extruded profile were measured in the same manner as in Example 1, and the average value and the difference between the maximum value and the minimum value were determined. Similar to Example 1, the surface-treated aluminum alloy extruded profile of Example 2 had no variation in its glossiness and surface roughness, and had a uniform appearance with no extrusion marks or surface defects.
The results are shown in Table 1.
[0027]
Example 3
The surface treatment was performed in the same manner as in Example 2 except that the sulfuric acid aqueous solution having a concentration of 150 g / liter was used as the treatment bath used in the first step anodizing treatment. The degree and the surface roughness (Ra) were measured in the same manner as in Example 1, and the average value and the difference between the maximum value and the minimum value were determined. Similar to Example 2, the surface-treated aluminum alloy extruded profile of Example 3 had no unevenness in glossiness and surface roughness, and had a uniform appearance with no extrusion marks or surface defects.
The results are shown in Table 1.
[0028]
Example 4
Surface treatment was performed in the same manner as in Example 2 except that the treatment bath used in the first step anodizing treatment was an aqueous oxalic acid solution having a concentration of 40 g / liter. Glossiness and surface roughness (Ra) were measured in the same manner as in Example 1, and the average value and the difference between the maximum value and the minimum value were determined. As in Example 2, the surface-treated aluminum alloy extruded profile of Example 4 had a uniform appearance with no variations in gloss and surface roughness, no extrusion marks or surface defects.
The results are shown in Table 1.
[0029]
Example 5
The surface treatment was performed in the same manner as in Example 2 except that the treatment bath used in the first step anodizing treatment was a tartaric acid aqueous solution having a concentration of 10 g / liter. The degree and the surface roughness (Ra) were measured in the same manner as in Example 1, and the average value and the difference between the maximum value and the minimum value were determined. Similar to Example 2, the surface-treated aluminum alloy extruded profile of Example 5 had no unevenness in its glossiness and surface roughness, and had a uniform appearance with no extrusion marks or surface defects.
The results are shown in Table 1.
[0030]
[Comparative Example 1]
As a pretreatment, after immersing in a sodium hydroxide aqueous solution having a concentration of 50 g / liter and a bath temperature of 50 ° C. for 5 minutes to remove the natural oxide film on the surface of the extruded aluminum alloy, in a hydrochloric acid aqueous solution having a concentration of 55 g / liter, Extruded aluminum alloy surface immersed in a bath temperature of 35 ° C. and a treatment time of 5 minutes, and then immersed in a 50 g / liter sodium hydroxide aqueous solution at a bath temperature of 50 ° C. and a treatment time of 10 minutes. The material was obtained.
[0031]
The gloss and surface roughness (Ra) of the obtained surface-treated aluminum alloy extruded profile were measured in the same manner as in Example 1 above, and the average value and the difference between the maximum value and the minimum value were determined. The surface-treated aluminum alloy extruded profile of Comparative Example 1 was confirmed to have an uneven distribution and uneven surface condition.
The results are shown in Table 1.
[0032]
[Table 1]
【The invention's effect】
According to the surface treatment method for an aluminum material of the present invention, rolling marks and extrusion marks at the time of forming the material disappear, surface gloss and color tone are uniform and reproducible, and the surface gloss is controlled over a wide range. And color tone can be imparted.
Claims (9)
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| JPS51138543A (en) * | 1975-05-27 | 1976-11-30 | Fuji Satsushi Kogyo Kk | Coloring process for aluminum or aluminum alloy |
| JPS53131238A (en) * | 1977-04-21 | 1978-11-15 | Sankyo Aruminiumu Kougiyou Kk | Electrolytic color formation method of aluminium |
| JPS565999A (en) * | 1979-06-28 | 1981-01-22 | Daidou Kofunyuugenkoushi | Forming of antiicorrosion aluminum oxide film |
| JPS5989796A (en) * | 1982-11-12 | 1984-05-24 | Hitachi Condenser Co Ltd | Manufacture of aluminum foil for electrolytic capacitor |
| US4502925A (en) * | 1984-06-11 | 1985-03-05 | American Hoechst Corporation | Process for aluminum surface preparation |
| JPS6455307A (en) * | 1987-08-25 | 1989-03-02 | Alps Electric Co Ltd | Production of acicular powder |
| JP2752422B2 (en) * | 1988-04-25 | 1998-05-18 | 昭和アルミニウム株式会社 | Method for producing aluminum material for electrolytic capacitor electrode |
| JPH08100290A (en) * | 1994-09-30 | 1996-04-16 | Sumitomo Light Metal Ind Ltd | Treatment of adhesive substrate of anodic oxide film forming aluminum |
| JPH09226262A (en) * | 1996-02-20 | 1997-09-02 | Konica Corp | Substrate for lithographic printing plate and its manufacture |
| JP3445134B2 (en) * | 1998-01-28 | 2003-09-08 | ワイケイケイ株式会社 | Method for producing gray-colored aluminum material and its colored body |
| JP3398601B2 (en) * | 1998-07-13 | 2003-04-21 | 松下電器産業株式会社 | Method for producing aluminum electrode foil for electrolytic capacitor and etching apparatus used for the same |
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