JP3903381B2 - How to paint aluminum alloy - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明はアルミニウム合金の塗装方法に関し、より詳しくは、クロムフリーの処理液を使用してアルミニウム合金の表面を処理するが、クロム酸塩法やリン酸−クロム酸塩法で処理した場合と比較して同等以上の効果を達成できるアルミニウム合金の塗装方法に関する。
【０００２】
【従来の技術】
アルミニウム合金の化成処理方法として、従来、アルカリ−クロム酸塩法、クロム酸塩法、リン酸−クロム酸塩法等のクロム系や、リン酸亜鉛法、ノンクロメート化成処理法（タンニン酸法）等の非クロム系が知られている（例えば、非特許文献１参照。）。
【０００３】
クロム系であるクロム酸塩法やリン酸−クロム酸塩法でアルミニウム合金の表面を化成処理した場合には、耐食性及び塗膜の密着性は良好であるが、クロム酸塩を使用するので環境問題が生じる。非クロム系であるリン酸亜鉛法やタンニン酸法でアルミニウム合金の表面を化成処理した場合には、塗膜の密着性は良好であるが、耐食性がクロム酸塩法と比較し劣るという問題があった。
【０００４】
近年、環境問題への配慮から、アルミニウム合金表面の化成処理について種々のノンクロメート法が提案されている（例えば、特許文献１〜６参照。）。しかしながら、耐食性及び塗膜の密着性の両方を同時に満足できる点でクロム酸塩法やリン酸−クロム酸塩法と同等以上の効果を達成できるノンクロメート化成処理方法がなく、更なる開発が続けられている。
【０００５】
【非特許文献１】
（社）表面技術協会編、「表面技術便覧」、日刊工業新聞社、１９９８年２月、ｐ．６９１
【特許文献１】
特開平７−９０６１４号公報
【特許文献２】
特開平１０−２３７６６７号公報
【特許文献３】
特開平１１−１３１２５４号公報
【特許文献４】
特開２０００−３４５７７号公報
【特許文献５】
特開２００２−２４９８８６号公報
【特許文献６】
特開２００２−２７５６４９号公報
【０００６】
【発明が解決しようとする課題】
本発明は、クロムフリーの処理液を使用してアルミニウム合金の表面を処理するが、クロム酸塩法やリン酸−クロム酸塩法で処理した場合と比較して同等以上の効果を達成できるアルミニウム合金の塗装方法を提供することを目的としている。
【０００７】
【課題を解決するための手段】
本発明者等は上記の課題を達成するために鋭意検討した結果、過マンガン酸又はマンガン酸の水溶性塩、リン酸の水溶性塩及びピロリン酸の水溶性塩を含有する処理液を用いてアルミニウム合金の表面を化成処理することにより耐食性及び塗膜の密着性の両方に優れた塗装アルミニウム合金製品が得られることを見出し、本発明を完成した。
【０００８】
即ち、本発明のアルミニウム合金の塗装方法は、アルミニウム合金の表面を、
過マンガン酸又はマンガン酸の水溶性塩の濃度が、ＫＭｎＯ4 量に換算して、０．５〜５０ｇ／Ｌであり、
リン酸の水溶性塩の濃度が、Ｎａ3 ＰＯ4 量に換算して、０．５〜１００ｇ／Ｌであり、
ピロリン酸の水溶性塩の濃度が、Ｋ4 Ｐ2 Ｏ7 量に換算して、０．５〜１００ｇ／Ｌであり、
液温が２５〜９５℃である
処理液で０．５〜２０分間化成処理することによりアルミニウム合金の表面を化成処理し、該化成処理した表面をカチオン電着塗装することを特徴とする。
【０００９】
【発明の実施の形態】
本発明の塗装方法の前段である表面処理方法（以下、本発明の表面処理方法と記載する）で化成処理するアルミニウム合金としては、種々の技術分野で実用されている全てのアルミニウム合金、例えば、ＪＩＳ Ｈ ５２０２で規定されているＡＣ１Ａ、ＡＣ１Ｂ、ＡＣ２Ａ、ＡＣ２Ｂ、ＡＣ３Ａ、ＡＣ４Ａ、ＡＡＣ４Ｂ、ＡＣ４Ｃ、ＡＣ４ＣＨ、ＡＣ４Ｄ、ＡＣ５Ａ、ＡＣ７Ａ、ＡＣ８Ａ、ＡＣ８Ｂ、ＡＣ８Ｃ、ＡＣ９Ａ、ＡＣ９Ｂ等のアルミニウム合金鋳物、ＪＩＳ Ｈ ５３０２で規定されているＡＤＣｌ、ＡＤＣ３、ＡＤＣ５、ＡＤＣ６、ＡＤＣ１０、ＡＤＣ１０Ｚ、ＡＤＣ１２、ＡＤＣ１２Ｚ、ＡＤＣ１４等のアルミニウム合金ダイカスト、ＪＩＳ Ｈ ４０００で規定されている合金番号２０１７、２２１９、３００３、３１０４、４０３２、５００５、５１５４、６１０１、６０６１、７０７５、８０２１等のアルミニウム合金展伸材が包含される。また、本発明で化成処理するアルミニウム合金製品の形態としては、金型鋳造品、砂型鋳造品、ダイカスト、展伸材等を例示することができる。
【００１０】
アルミニウム合金の表面を化成処理する前に、前処理することが好ましい。前処理は、例えば、機械的方法、溶剤法、アルカリ法、酸洗法の何れでも実施できる。例えば、アクタン７０（メルテックス社製、酸性フッ化アンモニウム）の濃度５ｇ／Ｌで温度４０℃の水溶液中に１分間浸漬し、その後水洗することで実施できる。
【００１１】
本発明の表面処理方法で用いる化成処理液は過マンガン酸又はマンガン酸の水溶性塩を含有し、好適には、カリウム塩、ナトリウム塩、リチウム塩等のアルカリ金属塩や、マグネシウム塩等のアルカリ土類金属塩を含有することができ、その他にアンモニウム塩を含有することもできる。化成処理液中の過マンガン酸又はマンガン酸の水溶性塩の濃度は、ＫＭｎＯ4 量に換算して、０．５〜５０ｇ／Ｌであり、好ましくは１〜３０ｇ／Ｌである。化成処理液中の過マンガン酸又はマンガン酸の水溶性塩の濃度が、ＫＭｎＯ4 量に換算して、０．５ｇ／Ｌ未満の場合には、化成処理後のアルミニウム合金表面の耐食性が不十分となる傾向がある。また、過マンガン酸又はマンガン酸の水溶性塩は化成処理液中に溶解度まで存在することができるが、化成処理液中の過マンガン酸又はマンガン酸の水溶性塩の濃度が５０ｇ／Ｌを超えて高くなってもそれに見合った耐食性の向上は見られない。
【００１２】
本発明の表面処理方法で用いる化成処理液はリン酸の水溶性塩を含有し、好適にはＮａ3 ＰＯ4 、Ｎａ2 ＨＰＯ4 、ＮａＨ2 ＰＯ4 、ＮＨ4 Ｈ2 ＰＯ4 、Ｍｎ（Ｈ2 ＰＯ4 ）2 、Ｚｎ（Ｈ2 ＰＯ4 ）2 等を含有することができる。化成処理液中のリン酸の水溶性塩の濃度は、Ｎａ3 ＰＯ4 量に換算して、０．５〜１００ｇ／Ｌであり、好ましくは１〜５０ｇ／Ｌである。化成処理液中のリン酸の水溶性塩の濃度が、Ｎａ3 ＰＯ4 量に換算して、０．５ｇ／Ｌ未満の場合には、化成処理後のアルミニウム合金表面の耐食性が不十分となる傾向がある。また、化成処理液中のリン酸の水溶性塩の濃度が１００ｇ／Ｌを超える場合には、アルミニウム合金の表面にスマットが生じ、塗装した時に外観不良となる。
【００１３】
本発明の表面処理方法で用いる化成処理液はピロリン酸の水溶性塩を含有し、好適にはＫ4 Ｐ2 Ｏ7 、Ｎａ4 Ｐ2 Ｏ7 、Ｎａ2 Ｈ2 Ｐ2 Ｏ7 、Ｋ2 Ｈ2 Ｐ2 Ｏ7 、（ＮＨ4 ）4 Ｐ2 Ｏ7 等を含有することができる。化成処理液中のピロリン酸の水溶性塩の濃度は、Ｋ4 Ｐ2 Ｏ7 量に換算して、０．５〜１００ｇ／Ｌであり、好ましくは１〜５０ｇ／Ｌである。化成処理液中のピロリン酸の水溶性塩の濃度が、Ｋ4 Ｐ2 Ｏ7 量に換算して、０．５ｇ／Ｌ未満の場合には、化成処理後のアルミニウム合金表面への塗膜の密着性が不十分となる傾向がある。また、化成処理液中のピロリン酸の水溶性塩の濃度が１００ｇ／Ｌを超える場合には、アルミニウム合金の表面にスマットが生じ、塗装した時に外観不良となる。
【００１４】
本発明の表面処理方法で用いる化成処理液は上記の組成を有するので、その化成処理液のｐＨは１０〜１３程度になる。
本発明の表面処理方法においては、化成処理液の液温を２５〜９５℃、好ましくは３０〜７０℃に維持して実施する。液温が２５℃未満の場合には、化成処理後のアルミニウム合金表面の耐食性が不十分となる傾向がある。また、液温が９５℃を超える場合には、化成処理液の蒸発が激しくなり、浴の管理が難しくなる傾向がある。
【００１５】
本発明の表面処理方法においては、化成処理時間は０．５〜２０分間であり、好ましくは０．７〜１５分間である。化成処理時間が０．５分間未満の場合には、化成処理後のアルミニウム合金表面の耐食性が不十分となる傾向がある。また、化成処理時間が２０分間を超えて長くなってもそれに見合った耐食性の向上は見られない。
【００１６】
上記の条件下で化成処理した後、水洗及び純水洗浄を行い、次いで乾燥する。乾燥については一般的には室温〜９０℃程度で１０〜１２０分間実施する。
本発明の表面処理方法で得られる表面処理アルミニウム合金製品はその表面を塗装することにより、特にカチオン電着塗装することにより耐食性及び塗膜の密着性の両方に優れており、クロム酸塩法やリン酸−クロム酸塩法で処理した場合と比較して同等以上の効果を達成できる。また、カチオン電着塗装した後、その表面に更に上塗塗装することもできる。
【００１７】
【実施例】
以下に、実施例及び従来例に基づいて本発明を具体的に説明する。
実施例１〜１７
ＡＤＣ−１２合金製の多数の試験片（５０ｍｍ×４０ｍｍ×０．５ｍｍ）を、アクタン７０（メルテックス社製）の濃度５ｇ／Ｌで液温４０℃の水溶液中に１分間浸漬し、その後室温での水道水洗浄を３０秒間実施し、次いで室温での純水洗浄を３０秒間実施した。
【００１８】
上記のように処理した各々の試験片を、次に、ＫＭｎＯ4 、Ｎａ3 ＰＯ4 及びＫ4 Ｐ2 Ｏ7 を第１表に示す濃度で含有する５０℃の化成処理液中に１分間浸漬し、その後室温での水道水洗浄を３０秒間実施し、次いで室温での純水洗浄を３０秒間実施した。最後に８０℃で２０分間乾燥を実施した。
【００１９】
次にカチオン電着塗装を室温の電着液中で１５０Ｖで２．５分間通電して実施し、電着後に１５０℃で２０分間の焼きつけを実施した。その後、更に、浸漬塗装法によりアクリル系焼きつけ塗料を塗布し、１０分間静置した後、１５０℃で２０分間の焼きつけを実施した。
【００２０】
塗装を行った試験片の外観について目視観察による評価した。その結果は第１表に示す通りであった。また、ＪＩＳ Ｋ ５４００の８．５．２に準拠した碁盤目テープ法（１ｍｍ間隔）による塗膜密着性試験を実施した。その結果は第１表に示す通りであった。更に、ＪＩＳ Ｋ ５４００の９．１に準拠した耐塩水噴霧試験法による耐食性試験（但し試験後の評価に関してはクロスカットの片側２ｍｍ、合計４ｍｍ幅以外の領域における腐食の有無で判定した。）を実施した。その結果は第１表に示す通りであった。
【００２１】
実施例１８〜２７
ＡＤＣ−１２合金製の多数の試験片（５０ｍｍ×４０ｍｍ×０．５ｍｍ）を、アクタン７０（メルテックス社製）の濃度５ｇ／Ｌで液温４０℃の水溶液中に１分間浸漬し、その後室温での水道水洗浄を３０秒間実施し、次いで室温での純水洗浄を３０秒間実施した。
【００２２】
上記のように処理した各々の試験片を、次に、ＫＭｎＯ4 濃度が５ｇ／Ｌ、Ｎａ3 ＰＯ4 濃度が１０ｇ／Ｌ、Ｋ4 Ｐ2 Ｏ7 濃度が１０ｇ／Ｌである化成処理液中に第２表に示す液温で第２表に示す時間浸漬し、その後室温での水道水洗浄を３０秒間実施し、次いで室温での純水洗浄を３０秒間実施した。最後に８０℃で２０分間乾燥を実施した。
【００２３】
次にカチオン電着塗装を室温の電着液中で１５０Ｖで２．５分間通電して実施し、電着後に１５０℃で２０分間の焼きつけを実施した。その後、更に、浸漬塗装法によりアクリル系焼きつけ塗料を塗布し、１０分間静置した後、１５０℃で２０分間の焼きつけを実施した。
【００２４】
塗装を行った試験片の外観について目視観察による評価した。その結果は第２表に示す通りであった。また、ＪＩＳ Ｋ ５４００の８．５．２に準拠した碁盤目テープ法（１ｍｍ間隔）による塗膜密着性試験を実施を実施した。その結果は第２表に示す通りであった。更に、ＪＩＳ Ｋ ５４００の９．１に準拠した耐塩水噴霧試験法による耐食性試験（但し試験後の評価に関してはクロスカットの片側２ｍｍ、合計４ｍｍ幅以外の領域における腐食の有無で判定した。）を実施した。その結果は第２表に示す通りであった。
【００２５】
従来例１（クロム酸塩法）
ＡＤＣ−１２合金製の試験片（５０ｍｍ×４０ｍｍ×０．５ｍｍ）を、アクタン７０（メルテックス社製）の濃度５ｇ／Ｌで液温４０℃の水溶液中に１分間浸漬し、その後室温での水道水洗浄を３０秒間実施し、次いで室温での純水洗浄を３０秒間実施した。
【００２６】
上記のように処理した試験片を、次に、アロジン６００（日本パーカライジング社製、クロム酸イオン及びフッ素イオンを含有する）を１．５ｇ／Ｌの濃度で含有する３０℃の化成処理液中に１．５分間浸漬し、その後室温での水道水洗浄を３０秒間実施し、次いで室温での純水洗浄を３０秒間実施した。最後に８０℃で２０分間乾燥を実施した。
【００２７】
次にカチオン電着塗装を室温の電着液中で１５０Ｖで２．５分間通電して実施し、電着後に１５０℃で２０分間の焼きつけを実施した。その後、更に、浸漬塗装法によりアクリル系焼きつけ塗料を塗布し、１０分間静置した後、１５０℃で２０分間の焼きつけを実施した。
【００２８】
塗装を行った試験片の外観について目視観察による評価した。その結果は第３表に示す通りであった。また、ＪＩＳ Ｋ ５４００の８．５．２に準拠した碁盤目テープ法（１ｍｍ間隔）による塗膜密着性試験を実施を実施した。その結果は第３表に示す通りであった。更に、ＪＩＳ Ｋ ５４００の９．１に準拠した耐塩水噴霧試験法による耐食性試験（但し試験後の評価に関してはクロスカットの片側２ｍｍ、合計４ｍｍ幅以外の領域における腐食の有無で判定した。）を実施した。その結果は第３表に示す通りであった。
【００２９】
【表１】
【表２】
第１〜３表に示すデータからも明らかなように、クロムフリーの処理液を使用してアルミニウム合金の表面を処理し、その表面を塗装する本発明の塗装方法においては、クロム酸塩法やリン酸−クロム酸塩法で処理した場合と比較して同等の効果を達成できる。
【００３２】
【発明の効果】
本発明の表面処理方法においては、クロムフリーの処理液を使用してアルミニウム合金の表面を処理するが、クロム酸塩法やリン酸−クロム酸塩法で処理した場合と比較して同等以上の効果を達成でき、クロム酸塩を使用しないので環境問題が生じない。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coating method of an aluminum alloy, and more specifically, the surface of an aluminum alloy is treated using a chromium-free treatment solution, but compared with the case of treating with a chromate method or a phosphoric acid-chromate method. It is related with the coating method of the aluminum alloy which can achieve the effect more than equivalent.
[0002]
[Prior art]
As a chemical conversion treatment method for aluminum alloys, conventional chromium-based methods such as alkali-chromate method, chromate method, phosphoric acid-chromate method, zinc phosphate method, non-chromate chemical conversion treatment method (tannic acid method) And the like are known (for example, see Non-Patent Document 1).
[0003]
When the surface of an aluminum alloy is subjected to chemical conversion treatment by the chromium-based chromate method or phosphoric acid-chromate method, the corrosion resistance and adhesion of the coating film are good, but the environment is used because chromate is used. Problems arise. When the surface of an aluminum alloy is subjected to a chemical conversion treatment using a non-chromium zinc phosphate method or tannic acid method, the adhesion of the coating film is good, but the corrosion resistance is inferior to the chromate method. there were.
[0004]
In recent years, various non-chromate methods have been proposed for chemical conversion treatment of an aluminum alloy surface in consideration of environmental problems (see, for example, Patent Documents 1 to 6). However, there is no non-chromate chemical conversion treatment method that can achieve the same or better effect than the chromate method and phosphoric acid-chromate method in that both corrosion resistance and coating film adhesion can be satisfied at the same time, and further development continues. It has been.
[0005]
[Non-Patent Document 1]
(Surface Technology Association), “Surface Technology Handbook”, Nikkan Kogyo Shimbun, February 1998, p. 691
[Patent Document 1]
JP-A-7-90614 [Patent Document 2]
JP-A-10-237667 [Patent Document 3]
Japanese Patent Application Laid-Open No. 11-1312254 [Patent Document 4]
JP 2000-34577 A [Patent Document 5]
Japanese Patent Laid-Open No. 2002-249886 [Patent Document 6]
JP-A-2002-275649 [0006]
[Problems to be solved by the invention]
In the present invention, the surface of an aluminum alloy is treated using a chromium-free treatment solution, but aluminum that can achieve an effect equal to or higher than the treatment by the chromate method or the phosphoric acid-chromate method. The object is to provide a method of painting an alloy.
[0007]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above-mentioned problems, the present inventors have used a treatment liquid containing a water-soluble salt of permanganic acid or manganic acid, a water-soluble salt of phosphoric acid, and a water-soluble salt of pyrophosphoric acid. The present inventors have found that a coated aluminum alloy product excellent in both corrosion resistance and coating film adhesion can be obtained by chemical conversion treatment of the surface of the aluminum alloy.
[0008]
That is, the aluminum alloy coating method of the present invention, the surface of the aluminum alloy,
The concentration of permanganic acid or water-soluble salt of manganic acid is 0.5 to 50 g / L in terms of KMnO 4 amount,
The concentration of the water-soluble salt of phosphoric acid is 0.5 to 100 g / L in terms of Na 3 PO 4 amount,
The concentration of the pyrophosphoric acid water-soluble salt is 0.5 to 100 g / L in terms of the amount of K 4 P 2 O 7 ,
The surface of the aluminum alloy is subjected to a chemical conversion treatment for 0.5 to 20 minutes with a treatment liquid having a liquid temperature of 25 to 95 ° C., and the surface subjected to the chemical conversion treatment is subjected to cationic electrodeposition coating .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the aluminum alloy that is subjected to the chemical conversion treatment by the surface treatment method (hereinafter referred to as the surface treatment method of the present invention ) that is the previous stage of the coating method of the present invention include all aluminum alloys that are practically used in various technical fields, for example, AC1A, AC1B, AC2A, AC2B, AC3A, AC4A, AAC4B, AC4C, AC4CH, AC4D, AC5A, AC7A, AC8A, AC8B, AC8C, AC9A, AC9B, and other aluminum alloy castings specified in JIS H5202, JIS H5302 ADCI, ADC3, ADC5, ADC6, ADC10, ADC10Z, ADC12, ADC12Z, ADC14 and other aluminum alloy die castings specified in JIS H 4000, alloy numbers 2017, 2219, 3003, 3104, 40 Wrought aluminum alloys such 2,5005,5154,6101,6061,7075,8021 are included. Examples of the form of the aluminum alloy product subjected to chemical conversion treatment in the present invention include a die casting product, a sand casting product, a die casting, a wrought material, and the like.
[0010]
It is preferable to pre-treat the surface of the aluminum alloy before chemical conversion treatment. The pretreatment can be performed by any of a mechanical method, a solvent method, an alkali method, and a pickling method, for example. For example, it can be carried out by immersing in an aqueous solution of Actan 70 (Meltex, manufactured by acidic ammonium fluoride) at a concentration of 5 g / L for 1 minute and then washing with water.
[0011]
The chemical conversion treatment solution used in the surface treatment method of the present invention contains permanganic acid or a water-soluble salt of manganic acid, preferably an alkali metal salt such as potassium salt, sodium salt or lithium salt, or an alkali such as magnesium salt. An earth metal salt can be contained, and an ammonium salt can also be contained. The concentration of permanganic acid or the water-soluble salt of manganic acid in the chemical conversion solution is 0.5 to 50 g / L, preferably 1 to 30 g / L, in terms of the amount of KMnO 4 . When the concentration of permanganic acid or water-soluble salt of manganic acid in the chemical conversion treatment liquid is less than 0.5 g / L in terms of KMnO 4 amount, the corrosion resistance of the aluminum alloy surface after chemical conversion treatment is insufficient. Tend to be. In addition, permanganic acid or a water-soluble salt of manganic acid can exist up to the solubility in the chemical conversion treatment solution, but the concentration of the water-soluble salt of permanganic acid or manganic acid in the chemical conversion treatment solution exceeds 50 g / L. However, even if it becomes high, the corrosion resistance improvement corresponding to it is not seen.
[0012]
The chemical conversion treatment solution used in the surface treatment method of the present invention contains a water-soluble salt of phosphoric acid, and preferably Na 3 PO 4 , Na 2 HPO 4 , NaH 2 PO 4 , NH 4 H 2 PO 4 , Mn (H 2 PO 4 ) 2 , Zn (H 2 PO 4 ) 2 or the like. The concentration of the water-soluble salt of phosphoric acid in the chemical conversion treatment liquid is 0.5 to 100 g / L, preferably 1 to 50 g / L, in terms of the amount of Na 3 PO 4 . When the concentration of the water-soluble salt of phosphoric acid in the chemical conversion treatment liquid is less than 0.5 g / L in terms of Na 3 PO 4 , the corrosion resistance of the surface of the aluminum alloy after chemical conversion treatment is insufficient. Tend. Further, when the concentration of the water-soluble salt of phosphoric acid in the chemical conversion solution exceeds 100 g / L, smut is generated on the surface of the aluminum alloy, resulting in poor appearance when painted.
[0013]
The chemical conversion treatment solution used in the surface treatment method of the present invention contains a water-soluble salt of pyrophosphate, and preferably K 4 P 2 O 7 , Na 4 P 2 O 7 , Na 2 H 2 P 2 O 7 , K 2. H 2 P 2 O 7 , (NH 4 ) 4 P 2 O 7 and the like can be contained. The concentration of the water-soluble salt of pyrophosphoric acid in the chemical conversion solution is 0.5 to 100 g / L, preferably 1 to 50 g / L, in terms of the amount of K 4 P 2 O 7 . When the concentration of the water-soluble salt of pyrophosphoric acid in the chemical conversion solution is less than 0.5 g / L in terms of K 4 P 2 O 7 , the coating film on the aluminum alloy surface after chemical conversion treatment There is a tendency for adhesion to be insufficient. Moreover, when the concentration of the water-soluble salt of pyrophosphoric acid in the chemical conversion solution exceeds 100 g / L, smut is generated on the surface of the aluminum alloy, resulting in poor appearance when painted.
[0014]
Since the chemical conversion liquid used in the surface treatment method of the present invention has the above composition, the chemical conversion liquid has a pH of about 10 to 13.
In the surface treatment method of the present invention, the chemical conversion treatment solution is maintained at a temperature of 25 to 95 ° C, preferably 30 to 70 ° C. When the liquid temperature is lower than 25 ° C., the corrosion resistance of the aluminum alloy surface after the chemical conversion treatment tends to be insufficient. On the other hand, when the liquid temperature exceeds 95 ° C., the chemical conversion liquid is apt to evaporate and the bath management tends to be difficult.
[0015]
In the surface treatment method of the present invention, the chemical conversion treatment time is 0.5 to 20 minutes, preferably 0.7 to 15 minutes. When the chemical conversion treatment time is less than 0.5 minutes, the corrosion resistance of the aluminum alloy surface after chemical conversion treatment tends to be insufficient. Further, even if the chemical conversion treatment time is longer than 20 minutes, no improvement in corrosion resistance corresponding to the chemical conversion treatment time is observed.
[0016]
After chemical conversion treatment under the above conditions, water washing and pure water washing are performed, followed by drying. The drying is generally performed at room temperature to about 90 ° C. for 10 to 120 minutes.
The surface-treated aluminum alloy product obtained by the surface treatment method of the present invention is excellent in both corrosion resistance and coating adhesion by coating its surface, in particular by cationic electrodeposition coating, Compared with the case where it processes by the phosphoric acid-chromate method, the effect more than equivalent can be achieved. Further, after the cationic electrodeposition coating, it is possible to further coat the surface.
[0017]
【Example】
The present invention will be specifically described below based on examples and conventional examples.
Examples 1-17
A large number of test pieces (50 mm × 40 mm × 0.5 mm) made of ADC-12 alloy were immersed in an aqueous solution having a concentration of 5 g / L of Actan 70 (manufactured by Meltex) for 1 minute, and then room temperature. The tap water was washed for 30 seconds, and then the pure water was washed at room temperature for 30 seconds.
[0018]
Each test piece treated as described above was then immersed in a chemical conversion solution at 50 ° C. containing KMnO 4 , Na 3 PO 4 and K 4 P 2 O 7 at the concentrations shown in Table 1 for 1 minute. Then, tap water washing at room temperature was carried out for 30 seconds, and then pure water washing at room temperature was carried out for 30 seconds. Finally, drying was performed at 80 ° C. for 20 minutes.
[0019]
Next, cationic electrodeposition coating was carried out by applying electricity at 150 V for 2.5 minutes in an electrodeposition solution at room temperature. After electrodeposition, baking was carried out at 150 ° C. for 20 minutes. Thereafter, an acrylic baking coating was further applied by a dip coating method, and after standing for 10 minutes, baking was performed at 150 ° C. for 20 minutes.
[0020]
The appearance of the coated test piece was evaluated by visual observation. The results were as shown in Table 1. Moreover, the coating-film adhesiveness test by the cross-cut tape method (1 mm space | interval) based on JIS K5400 8.5.2 was implemented. The results were as shown in Table 1. Furthermore, the corrosion resistance test by the salt spray test method based on 9.1 of JIS K 5400 (however, the evaluation after the test was determined by the presence or absence of corrosion in a region other than 2 mm on one side of the crosscut and a total width of 4 mm). Carried out. The results were as shown in Table 1.
[0021]
Examples 18-27
A large number of test pieces (50 mm × 40 mm × 0.5 mm) made of ADC-12 alloy were immersed in an aqueous solution having a concentration of 5 g / L of Actan 70 (manufactured by Meltex) for 1 minute, and then room temperature. The tap water was washed for 30 seconds, and then the pure water was washed at room temperature for 30 seconds.
[0022]
Each test piece treated as described above was then placed in a chemical conversion treatment solution having a KMnO 4 concentration of 5 g / L, a Na 3 PO 4 concentration of 10 g / L, and a K 4 P 2 O 7 concentration of 10 g / L. The sample was immersed in the solution temperature shown in Table 2 for the time shown in Table 2, followed by washing with tap water at room temperature for 30 seconds, and then washing with pure water at room temperature for 30 seconds. Finally, drying was performed at 80 ° C. for 20 minutes.
[0023]
Next, cationic electrodeposition coating was carried out by applying electricity at 150 V for 2.5 minutes in an electrodeposition solution at room temperature. After electrodeposition, baking was carried out at 150 ° C. for 20 minutes. Thereafter, an acrylic baking coating was further applied by a dip coating method, and after standing for 10 minutes, baking was performed at 150 ° C. for 20 minutes.
[0024]
The appearance of the coated test piece was evaluated by visual observation. The results were as shown in Table 2. Moreover, the coating-film adhesiveness test by the cross-cut tape method (1 mm space | interval) based on JIS K5400 8.5.2 was implemented. The results were as shown in Table 2. Furthermore, the corrosion resistance test by the salt spray test method based on 9.1 of JIS K 5400 (however, the evaluation after the test was determined by the presence or absence of corrosion in a region other than 2 mm on one side of the crosscut and a total width of 4 mm). Carried out. The results were as shown in Table 2.
[0025]
Conventional Example 1 (chromate method)
A test piece (50 mm × 40 mm × 0.5 mm) made of ADC-12 alloy is immersed in an aqueous solution having a concentration of 5 g / L of Actan 70 (manufactured by Meltex) for 1 minute and then at room temperature. A tap water cleaning was performed for 30 seconds, and then a pure water cleaning at room temperature was performed for 30 seconds.
[0026]
The test piece treated as described above was then placed in a chemical conversion treatment solution at 30 ° C. containing Alodine 600 (manufactured by Nihon Parkerizing Co., Ltd., containing chromate ions and fluorine ions) at a concentration of 1.5 g / L. After dipping for 1.5 minutes, tap water cleaning at room temperature was performed for 30 seconds, and then pure water cleaning at room temperature was performed for 30 seconds. Finally, drying was performed at 80 ° C. for 20 minutes.
[0027]
Next, cationic electrodeposition coating was carried out by applying electricity at 150 V for 2.5 minutes in an electrodeposition solution at room temperature. After electrodeposition, baking was carried out at 150 ° C. for 20 minutes. Thereafter, an acrylic baking coating was further applied by a dip coating method, and after standing for 10 minutes, baking was performed at 150 ° C. for 20 minutes.
[0028]
The appearance of the coated test piece was evaluated by visual observation. The results were as shown in Table 3. Moreover, the coating-film adhesiveness test by the cross-cut tape method (1 mm space | interval) based on JIS K5400 8.5.2 was implemented. The results were as shown in Table 3. Furthermore, the corrosion resistance test by the salt spray test method based on 9.1 of JIS K 5400 (however, the evaluation after the test was determined by the presence or absence of corrosion in a region other than 2 mm on one side of the crosscut and a total width of 4 mm). Carried out. The results were as shown in Table 3.
[0029]
[Table 1]
[Table 2]
As is clear from the data shown in Tables 1 to 3, in the coating method of the present invention in which the surface of the aluminum alloy is treated using a chromium-free treatment liquid and the surface is coated , the chromate method or The same effect can be achieved as compared with the case where the phosphoric acid-chromate method is used.
[0032]
【The invention's effect】
In the surface treatment method of the present invention, the surface of the aluminum alloy is treated using a chromium-free treatment solution, which is equivalent to or better than the case of treatment by the chromate method or the phosphoric acid-chromate method. The effect can be achieved, and no environmental problems occur because chromate is not used.
Claims (3)
過マンガン酸又はマンガン酸の水溶性塩の濃度が、ＫＭｎＯ4 量に換算して、０．５〜５０ｇ／Ｌであり、
リン酸の水溶性塩の濃度が、Ｎａ3 ＰＯ4 量に換算して、０．５〜１００ｇ／Ｌであり、
ピロリン酸の水溶性塩の濃度が、Ｋ4 Ｐ2 Ｏ7 量に換算して、０．５〜１００ｇ／Ｌであり、
液温が２５〜９５℃である
処理液で０．５〜２０分間化成処理することによりアルミニウム合金の表面を化成処理し、該化成処理した表面をカチオン電着塗装することを特徴とするアルミニウム合金の塗装方法。The surface of the aluminum alloy,
The concentration of permanganic acid or water-soluble salt of manganic acid is 0.5 to 50 g / L in terms of KMnO 4 amount,
The concentration of the water-soluble salt of phosphoric acid is 0.5 to 100 g / L in terms of Na 3 PO 4 amount,
The concentration of the pyrophosphoric acid water-soluble salt is 0.5 to 100 g / L in terms of the amount of K 4 P 2 O 7 ,
An aluminum alloy characterized by subjecting the surface of the aluminum alloy to chemical conversion treatment by a chemical conversion treatment for 0.5 to 20 minutes with a treatment liquid having a liquid temperature of 25 to 95 ° C., and subjecting the chemical conversion treatment surface to cationic electrodeposition coating Painting method.
過マンガン酸又はマンガン酸の水溶性塩の濃度が、ＫＭｎＯ4 量に換算して、１〜３０ｇ／Ｌであり、
リン酸の水溶性塩の濃度が、Ｎａ3 ＰＯ4 量に換算して、１〜５０ｇ／Ｌであり、
ピロリン酸の水溶性塩の濃度が、Ｋ4 Ｐ2 Ｏ7 量に換算して、１〜５０ｇ／Ｌであり、
液温が２５〜９５℃である
処理液で０．５〜２０分間化成処理することによりアルミニウム合金の表面を化成処理し、該化成処理した表面をカチオン電着塗装することを特徴とする請求項１記載のアルミニウム合金の塗装方法。The surface of the aluminum alloy,
The concentration of permanganic acid or water-soluble salt of manganic acid is 1 to 30 g / L in terms of KMnO 4 amount,
The concentration of the water-soluble salt of phosphoric acid is 1 to 50 g / L in terms of Na 3 PO 4 amount,
The concentration of the water-soluble salt of pyrophosphate is 1 to 50 g / L in terms of the amount of K 4 P 2 O 7 ,
The surface of the aluminum alloy is subjected to a chemical conversion treatment with a treatment liquid having a liquid temperature of 25 to 95 ° C for 0.5 to 20 minutes, and the surface subjected to the chemical conversion treatment is subjected to cationic electrodeposition coating. A method for coating an aluminum alloy according to 1.
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