JP3224639B2 - Method for forming colorless chromate film on aluminum wheels - Google Patents
Method for forming colorless chromate film on aluminum wheelsInfo
- Publication number
- JP3224639B2 JP3224639B2 JP17993293A JP17993293A JP3224639B2 JP 3224639 B2 JP3224639 B2 JP 3224639B2 JP 17993293 A JP17993293 A JP 17993293A JP 17993293 A JP17993293 A JP 17993293A JP 3224639 B2 JP3224639 B2 JP 3224639B2
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- test
- film
- aqueous solution
- corrosion resistance
- acidic aqueous
- Prior art date
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- Chemical Treatment Of Metals (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、アルミホイールの塗装
前処理方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for pre-painting an aluminum wheel.
【０００２】[0002]
【従来技術】アルミニウム又はアルミニウム合金の表面
処理方法としては、陽極酸化（アルマイト法）、着色処
理、化学皮膜処理（反応クロメート法、ＭＢＶ法、ベー
マイト法等）が一般に知られている。アルミホイールを
塗装する場合、耐食性及び塗装密着性の向上のため塗装
前処理として反応クロメート処理、ノンクロメート処理
（有機金属塩皮膜等）、陽極酸化皮膜処理が施されてい
る。2. Description of the Related Art Anodizing (alumite method), coloring treatment, and chemical film treatment (reaction chromate method, MBV method, boehmite method, etc.) are generally known as surface treatment methods for aluminum or aluminum alloys. When painting aluminum wheels, reactive chromate treatment, non-chromate treatment (organic metal salt film etc.), and anodic oxide film treatment are applied as pre-coating treatments to improve corrosion resistance and paint adhesion.
【０００３】アルミホイールの光輝性を生かしたクリヤ
ー塗装用前処理を考えた場合、ノンクロメート処理（有
機金属塩皮膜）では耐食性が不足しており、陽極酸化膜
では耐食性は良好であるが皮膜量が多く光沢が無くなる
ため、素材の光輝性を重視したクリヤー塗装用の前処理
としては不向きである。反応クロメート皮膜は優れた耐
食性を有しているが、無色の皮膜外観を求められた場
合、クロム付着量が１０ｍｇ／ｍ2以下に制限されるた
め糸錆耐食性が不足する。糸錆とは、金属表面の塗膜を
通して水が金属表面に侵入して局部的に電解腐食を起こ
し幅０．１〜０．５ｍｍ程度のミミズ這い状の錆が経時
と共に進行して行く状態を言う。[0003] Considering the pretreatment for clear coating utilizing the glitter of aluminum wheels, the non-chromate treatment (organic metal salt film) is insufficient in corrosion resistance, and the anodic oxide film has good corrosion resistance, but the amount of film is good. However, it is not suitable as a pretreatment for clear coating, which emphasizes the glitter of the material. The reactive chromate film has excellent corrosion resistance, but when a colorless film appearance is required, the chromium adhesion amount is limited to 10 mg / m 2 or less, resulting in insufficient rust corrosion resistance. Yarn rust is a state in which water penetrates into the metal surface through a coating film on the metal surface, locally causes electrolytic corrosion, and earthworm crawling rust with a width of about 0.1 to 0.5 mm progresses over time. To tell.
【０００４】[0004]
【発明が解決しようとする課題】以上のようにアルミホ
イールの素材の光輝性を保持し、且つ塗装後の耐食性並
びに密着性に満足できる前処理方法はまだ見いだされて
いない。本発明の目的はアルミホイール素材の光輝性を
保持し、且つ塗装後耐食性（特に糸錆耐食性）、密着性
に優れた前処理皮膜を形成する前処理方法を提供するこ
とにある。As described above, no pretreatment method has yet been found which can maintain the brilliancy of the material of the aluminum wheel and satisfy the corrosion resistance and adhesion after coating. SUMMARY OF THE INVENTION An object of the present invention is to provide a pretreatment method for forming a pretreatment film that retains the brilliancy of an aluminum wheel material, has excellent corrosion resistance after coating (particularly, rust corrosion resistance), and has excellent adhesion.
【０００５】[0005]
【課題を解決するための手段】本発明者らは上記目的を
達成する為に鋭意研究を重ねた結果、アルミホイールを
特定した濃度の６価クロムイオン、硫酸イオン及びフッ
素イオンを含有し、かつ特定したｐＨに調整した酸性水
溶液中で、特定の電解方法で陰極電解処理することによ
り前記目的に適応した無色のクロメート皮膜を得ること
が出来ることを見いだし、かつ該皮膜は塗装後糸錆耐食
性、塗料密着性に優れている事を見いだして本発明を完
成するに至った。Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, the aluminum wheel contains hexavalent chromium ion, sulfate ion and fluorine ion at a specified concentration, and In an acidic aqueous solution adjusted to a specified pH, it was found that a colorless chromate film adapted for the above-mentioned purpose can be obtained by performing cathodic electrolysis by a specific electrolytic method, and the film has a rust corrosion resistance after coating, The inventors have found that they have excellent paint adhesion, and have completed the present invention.
【０００６】すなわち、本発明は、アルミホイールを６
価クロムイオン２ｇ／ｌ以上、硫酸イオン２０〜２００
０ｐｐｍ及びフッ素１０〜４００ｐｐｍを含有するｐＨ
０．６〜１．７の酸性水溶液中に浸漬し、該アルミホイ
ールが該酸性水溶液中に全没してから０．５〜１５Ａ／
ｄｍ2の電流密度で４秒以上陰極電解処理し、通電終了
後１〜３００秒経過してから該酸性水溶液から取り出す
ことを特徴とするアルミホイールの無色クロメート皮膜
形成方法を提供する。以下本発明の構成について具体的
に説明する。[0006] That is, the present invention provides an aluminum wheel 6
Chromium ion 2g / l or more, sulfate ion 20-200
PH containing 0 ppm and 10 to 400 ppm of fluorine
Immersed in an acidic aqueous solution of 0.6 to 1.7, and 0.5 to 15 A /
A method for forming a colorless chromate film on an aluminum wheel, comprising performing cathodic electrolysis at a current density of dm 2 for 4 seconds or more, and removing from the acidic aqueous solution 1 to 300 seconds after the end of energization. Hereinafter, the configuration of the present invention will be specifically described.
【０００７】まず、酸性水溶液を構成する各成分につい
て説明する。６価クロムイオンとしては、無水クロム
酸、重クロム酸、及び重クロム酸のアルカリ金属塩類な
どがあげられ、それらの化合物から任意に１種又は２種
以上を選んで使用でき、その濃度範囲は２〜５０ｇ／ｌ
である。６価クロムイオン濃度が２ｇ／ｌ未満では、十
分な耐食性を有するクロメート皮膜が得られず、５０ｇ
／ｌを越えても性能上は問題ないが、排水処理等の負担
がかかり不経済である。また、電解処理を行うにつれ
て、３価のクロムイオンが増加するが、本発明を実施す
るに当たり、皮膜性能上３価のクロムイオンの濃度は影
響が少ないので、特に３価のクロムイオンについては限
定範囲を設ける必要がない。First, each component constituting the acidic aqueous solution will be described. Hexavalent chromium ions include chromic anhydride, dichromic acid, and alkali metal salts of dichromic acid, and one or more of these compounds can be arbitrarily selected and used, and the concentration range is as follows. 2 to 50 g / l
It is. If the hexavalent chromium ion concentration is less than 2 g / l, a chromate film having sufficient corrosion resistance cannot be obtained, and
Even if it exceeds / l, there is no problem in performance, but the burden of wastewater treatment and the like is high and uneconomical. In addition, trivalent chromium ions increase as the electrolytic treatment is performed. However, in carrying out the present invention, the concentration of trivalent chromium ions has little effect on film performance. There is no need to set a range.
【０００８】硫酸イオンとしては、硫酸、硫酸のアルカ
リ金属塩類が使用でき、その濃度範囲は２０〜２０００
ｐｐｍである。その濃度が２０ｐｐｍ未満では、無色の
クロメート皮膜が形成されない。又、２０００ｐｐｍを
越えると、クロム付着量が減少し耐食性が低下するので
好ましくない。As sulfate ions, sulfuric acid and alkali metal salts of sulfuric acid can be used, and the concentration range is from 20 to 2,000.
ppm. If the concentration is less than 20 ppm, a colorless chromate film will not be formed. On the other hand, when the content exceeds 2,000 ppm, the amount of chromium attached is reduced and the corrosion resistance is reduced, which is not preferable.
【０００９】フッ素はフッ素イオン及び／又は、錯フッ
素イオンの形で存在し、フッ素イオンの供給源として
は、例えばフッ化水素酸、錯フッ素イオンの供給源とし
てはケイフッ化水素酸、ジルコンフッ化水素酸、ホウフ
ッ化水素酸等から任意に選んで使用することができる
が、ジルコンフッ化水素酸をもちいるのがより好まし
い。フッ素としての濃度範囲は１０〜４００ｐｐｍであ
る。１０ｐｐｍ未満では塗装後耐食性に優れたクロメー
ト皮膜を形成せず、４００ｐｐｍを越えると、電解によ
るクロメート皮膜形成を抑制するので、所望するクロム
付着量が得難くなり、比較的少ないクロム付着量でも皮
膜が着色してしまう為、クリヤー塗装用として不適当で
ある。Fluorine exists in the form of fluorine ions and / or complex fluoride ions. The source of the fluorine ions is, for example, hydrofluoric acid, and the source of the complex fluoride ions is hydrosilicofluoric acid, zircon hydrogen fluoride. An acid, borofluoric acid, or the like can be arbitrarily selected and used, but zircon hydrofluoric acid is more preferably used. The concentration range as fluorine is 10 to 400 ppm. If it is less than 10 ppm, a chromate film excellent in corrosion resistance after coating is not formed, and if it exceeds 400 ppm, the formation of a chromate film by electrolysis is suppressed, so that it is difficult to obtain a desired amount of chromium coating, and even if the amount of chromium is relatively small, the film can be formed. It is unsuitable for clear coating because of coloring.
【００１０】酸性水溶液のｐＨはその値を０．６〜１．
７の範囲に限定する。ｐＨをコントロールするために
は、水酸化アンモニウム、アルカリ金属水酸化物、アル
カリ金属炭酸化合物、クロム酸及び硫酸等より任意に選
んで水溶液に加えることが出来る。ｐＨが０．６未満で
も塗装性能上は問題ないが、陰極電解処理することによ
り処理液のｐＨが上昇するため、工業生産上常時ｐＨ調
整が必要となり維持すること及びコントロールすること
が困難である。ｐＨが１．７を越えるとクロメート皮膜
付着量が急激に減少し、適性クロム付着量を得るのが困
難となる。The pH of the acidic aqueous solution is set to a value of 0.6 to 1.
7 range. In order to control the pH, it can be arbitrarily selected from ammonium hydroxide, alkali metal hydroxide, alkali metal carbonate, chromic acid, sulfuric acid and the like and added to the aqueous solution. Even if the pH is less than 0.6, there is no problem in the coating performance, but since the pH of the processing solution is increased by the cathodic electrolysis, it is necessary to constantly adjust the pH in industrial production, and it is difficult to maintain and control the pH. . When the pH exceeds 1.7, the amount of chromate film adhered decreases sharply, and it becomes difficult to obtain an appropriate amount of chromium film adhered.
【００１１】処理液の温度は特定するものではないが、
電解による皮膜析出反応を一定条件で行うために、３０
℃〜６０℃の範囲から選ばれた温度で一定に維持するこ
とが必要である。ここで、３０℃以下では電解による発
熱があるため温度維持に冷却が必要となり工業生産的に
は不経済である。また、６０℃より高くしても、生成す
る皮膜の特性に大きな変化はないが、電解処理後、次の
水洗工程に移行する間に被処理物に処理液が付着したま
ま乾いてしまい、水洗工程での洗浄性を低下させるので
好ましくない。Although the temperature of the processing liquid is not specified,
In order to perform the film deposition reaction by electrolysis under certain conditions, 30
It is necessary to keep the temperature constant at a temperature selected from the range of 60C to 60C. Here, when the temperature is 30 ° C. or less, heat is generated by electrolysis, and cooling is required to maintain the temperature, which is uneconomical for industrial production. Further, even if the temperature is higher than 60 ° C., there is no significant change in the characteristics of the formed film. However, after the electrolytic treatment, the processing liquid adheres to the object to be processed and dries while moving to the next washing step. It is not preferable because the washing property in the process is lowered.
【００１２】次に電解処理は被処理物を陰極とし、陽極
には鉛系合金電極、ステンレス、チタン白金等を用いて
電解処理を行う。電解処理の条件は、陰極における電解
電流密度を０．５〜１５Ａ／ｄｍ2の範囲で行う。電流
密度が０．５Ａ／ｄｍ2よりも低いときはクロメート皮
膜が形成され難く、また、１５Ａ／ｄｍ2より高いと皮
膜が着色し、さらに皮膜の再溶解が起こり、本発明の目
的である無色のクロメート皮膜は得られない。Next, in the electrolytic treatment, an object to be treated is used as a cathode, and an electrolytic treatment is performed using a lead-based alloy electrode, stainless steel, titanium platinum or the like as an anode. The conditions for the electrolytic treatment are such that the electrolytic current density at the cathode is in the range of 0.5 to 15 A / dm 2 . When the current density is lower than 0.5 A / dm 2, it is difficult to form a chromate film. When the current density is higher than 15 A / dm 2 , the film is colored, and the film is redissolved. Cannot be obtained.
【００１３】電解処理を行う際の通電開始は必ずアルミ
ホイールが該酸性水溶液に完全に浸漬されてから行う。
これは実際の処理を行うときにはアルミホイールの浸漬
が開始されてから完全に該酸性水溶液中に全没するまで
には数１０秒を要するため、通電状態で浸漬するとアル
ミホイールの部位（上下）により電解時間が変化するこ
とにより均一な皮膜形成が困難になるためである。電解
が開始されてからの電解時間は形成皮膜量（クロム付着
量）を所望の範囲とするために４秒以上にコントロール
される。形成皮膜量（クロム付着量）を変動させる要因
としては種々挙げられるが、本発明の方法においては、
処理液の各成分の濃度、ｐＨ、温度および電流密度等
を、それぞれ本発明の好ましい条件に固定しておき、電
解時間を変えることにより所望のクロム付着量に制御す
ることができる。また、その逆に電解時間を固定して、
電流密度を変えることによりクロム付着量を制御するこ
ともできる。電解が所定の時間行われた後は、アルミホ
イールを、通電を停止した状態で１〜３００秒間該酸性
水溶液中にて保持する。アルミホイールを通電状態で引
き上げたり、通電を停止しても１秒未満の時間内に引き
上げた場合には、アルミホイール表面に形成された皮膜
は黄色を呈し、クリア塗装下地には適さない皮膜となっ
てしまう。一方、３００秒を超えて保持された場合には
アルミホイールに形成された皮膜は茶褐色を呈し、クリ
ア塗装下地には適さない皮膜となる。なお、生産ライン
における電解処理液中のアルミホイールの姿勢のバラツ
キ等を考慮すると、全体を均一の安定したクロム付着量
とするため、電流密度１〜３Ａ／ｄｍ2で１５〜６０秒
の陰極電解処理とするのが好ましい。The energization in the electrolytic treatment is always started after the aluminum wheel is completely immersed in the acidic aqueous solution.
This takes several tens of seconds from the start of immersion of the aluminum wheel to the complete immersion in the acidic aqueous solution when performing the actual treatment. This is because a change in the electrolysis time makes it difficult to form a uniform film. The electrolysis time from the start of the electrolysis is controlled to 4 seconds or more in order to keep the formed film amount (the amount of chromium adhered) in a desired range. There are various factors that change the amount of the formed film (the amount of chromium adhered), but in the method of the present invention,
The concentration, pH, temperature, current density, etc., of each component of the treatment liquid are fixed under preferable conditions of the present invention, and the desired amount of chromium can be controlled by changing the electrolysis time. On the contrary, fix the electrolysis time,
By changing the current density, the amount of deposited chromium can be controlled. After the electrolysis has been performed for a predetermined time, the aluminum wheel is held in the acidic aqueous solution for 1 to 300 seconds in a state where the current is stopped. If the aluminum wheel is pulled up while energized, or if it is pulled up in less than 1 second even after the energization is stopped, the film formed on the aluminum wheel surface will turn yellow, and a film that is not suitable for a clear paint base turn into. On the other hand, when the film is held for more than 300 seconds, the film formed on the aluminum wheel exhibits a brown color, which is not a film suitable for a clear coating base. In consideration of the variation in the position of the aluminum wheel in the electrolytic solution on the production line, the cathode electrolysis is performed at a current density of 1 to 3 A / dm 2 for 15 to 60 seconds in order to obtain a uniform and stable chromium deposition amount. Preferably, it is a treatment.
【００１４】本発明において形成された皮膜のクロム付
着量は特に限定されないが、５０〜２５０ｍｇ／ｍ2の
範囲が好適である。クロム付着量が５０ｍｇ／ｍ2未満
では、塗装後耐食性、特に糸錆性が劣り、また、２５０
ｍｇ／ｍ2を越えるとクロメート皮膜が着色しクリヤー
塗装用に適さない。ただし、有色塗装の場合は、２５０
ｍｇ／ｍ2以上でも使用できる。The amount of chromium deposited on the film formed in the present invention is not particularly limited, but is preferably in the range of 50 to 250 mg / m 2 . When the chromium adhesion amount is less than 50 mg / m 2 , the corrosion resistance after coating, particularly the rust resistance, is poor.
If it exceeds mg / m 2 , the chromate film will be colored and not suitable for clear coating. However, in the case of colored paint, 250
mg / m 2 or more can be used.
【００１５】また、該酸性処理液にコロイダルシリカ、
乾式シリカ、珪酸アルカリ金属塩等の化合物を含有させ
ることにより、無色で比較的厚膜のクロメート皮膜を形
成させることもできる。Further, colloidal silica,
By containing a compound such as fumed silica or an alkali metal silicate, a colorless and relatively thick chromate film can be formed.
【００１６】本発明により陰極電解処理されたアルミホ
イールは、水洗した後乾燥して、塗装下地用として適用
される。また、必要に応じて、前記水洗と乾燥の間に一
般的に用いられているクロメート水溶液、及び有機化合
物などによる後処理を行うこともできる。The aluminum wheel which has been subjected to the cathodic electrolysis according to the present invention is washed with water, dried and applied as a coating base. If necessary, a post-treatment with an aqueous chromate solution, an organic compound, and the like, which are generally used between the water washing and drying, can be performed.
【００１７】[0017]
【実施例】次に、本発明を実施例と比較例を挙げて具体
的に説明する。試験板は、一般にアルミホイールに用い
られるアルミニウム鋳造用合金（ＪＩＳ記号ＡＣ４Ｃ、
サイズ７０×１５０×７ｍ／ｍ）板の表面を研削したも
のを、アルカリ脱脂洗浄して表面を清浄にした後、電解
処理に供した。Next, the present invention will be specifically described with reference to examples and comparative examples. The test plate is an aluminum casting alloy (JIS symbol AC4C, commonly used for aluminum wheels).
After grinding the surface of the plate (size 70 × 150 × 7 m / m), the surface was cleaned by alkali degreasing and cleaning, and then subjected to electrolytic treatment.
【００１８】（実施例１〜３）６価クロムイオンを無水
クロム酸で２０ｇ／ｌ、硫酸イオンを硫酸で４００ｐｐ
ｍ、ジルコンフッ化水素酸でフッ素を１００ｐｐｍ添加
した酸性水溶液のｐＨを水酸化アンモニウムを用いて表
１に示した条件（実施例１：ｐＨ０．６、実施例２：ｐ
Ｈ１．０、実施例３：ｐＨ１．６）に調整した。試験板
を４０℃に加温した前記酸性水溶液に浸漬後、通電を開
始し、電流密度を２Ａ／ｄｍ2で、３０秒陰極電解し
た。通電終了後５秒間前記酸性水溶液中に保持し、試験
板を取り出し水洗及び脱イオン水洗浄を行った後１００
℃の乾燥炉で５分間乾燥した。次に試験板に熱硬化型ア
クリル樹脂クリヤーを塗装し（膜厚３０μ）１４０℃３
０分焼付け乾燥後、耐食性試験（糸錆試験、塩水噴霧試
験）を実施した。結果を表１に示す。(Examples 1 to 3) Hexavalent chromium ions were 20 g / l with chromic anhydride and sulfate ions were 400 pp with sulfuric acid.
m, the pH of an acidic aqueous solution to which 100 ppm of fluorine was added with zircon hydrofluoric acid using ammonium hydroxide under the conditions shown in Table 1 (Example 1: pH 0.6, Example 2: p
H1.0, Example 3: pH 1.6). After the test plate was immersed in the acidic aqueous solution heated to 40 ° C., energization was started and cathodic electrolysis was performed at a current density of 2 A / dm 2 for 30 seconds. After the completion of energization, the sample was kept in the acidic aqueous solution for 5 seconds, the test plate was taken out, washed with water and washed with deionized water, and then washed for 100 seconds.
It dried for 5 minutes in the drying oven of ° C. Next, a thermosetting acrylic resin clear was applied to the test plate (30 μm in thickness) at 140 ° C.
After baking and drying for 0 minutes, a corrosion resistance test (yarn rust test, salt spray test) was performed. Table 1 shows the results.
【００１９】（比較例１〜２）６価クロムイオンを無水
クロム酸で２０ｇ／ｌ、硫酸イオンを硫酸で４００ｐｐ
ｍ、ジルコンフッ化水素酸でフッ素を１００ｐｐｍ添加
した酸性水溶液のｐＨを水酸化アンモニウムを用いて表
１に示した条件（比較例１：ｐＨ２．０、比較例２：ｐ
Ｈ３．０）に調整し、実施例１と同様の電解処理、塗装
を行い、耐食性試験を実施した。結果を表１に示す。(Comparative Examples 1-2) Hexavalent chromium ions were 20 g / l with chromic anhydride, and sulfate ions were 400 pp with sulfuric acid.
m, the pH of an acidic aqueous solution to which 100 ppm of fluorine was added with zircon hydrofluoric acid using ammonium hydroxide under the conditions shown in Table 1 (Comparative Example 1: pH 2.0, Comparative Example 2: p
H3.0), the same electrolytic treatment and coating as in Example 1 were performed, and a corrosion resistance test was performed. Table 1 shows the results.
【００２０】（比較例３）６価クロムイオンを無水クロ
ム酸で２０ｇ／ｌ、硫酸イオンを硫酸で１０ｐｐｍ、ジ
ルコンフッ化水素酸でフッ素を５ｐｐｍ添加した酸性水
溶液のｐＨを水酸化アンモニウムを用いて１．０に調整
し、実施例１と同様の電解処理、塗装を行い、耐食性試
験を実施した。結果を表１に示す。(Comparative Example 3) The pH of an acidic aqueous solution in which hexavalent chromium ions were added with chromic anhydride at 20 g / l, sulfate ions at 10 ppm with sulfuric acid, and zircon hydrofluoric acid at 5 ppm with fluorine was adjusted to 1 pH using ammonium hydroxide. Was adjusted to 0.0, electrolytic treatment and coating were performed in the same manner as in Example 1, and a corrosion resistance test was performed. Table 1 shows the results.
【００２１】（実施例４）６価クロムイオンを無水クロ
ム酸で５ｇ／ｌ、硫酸イオンを硫酸で１００ｐｐｍ、硅
フッ化水素酸でフッ素を３０ｐｐｍ添加した酸性水溶液
のｐＨを水酸化アンモニウムを用いて１．０に調整し、
実施例１と同様の電解処理、塗装を行い、耐食性試験を
実施した。結果を表１に示す。Example 4 The pH of an acidic aqueous solution obtained by adding hexavalent chromium ions to chromic anhydride at 5 g / l, sulfuric acid ions to sulfuric acid at 100 ppm, and fluorosilicic acid to fluorine at 30 ppm was adjusted using ammonium hydroxide. Adjust to 1.0,
The same electrolytic treatment and painting as in Example 1 were performed, and a corrosion resistance test was performed. Table 1 shows the results.
【００２２】（実施例５）６価クロムイオンを無水クロ
ム酸で５０ｇ／ｌ、硫酸イオンを硫酸で１ｇ／ｌ、ジル
コンフッ化水素酸でフッ素を４００ｐｐｍ添加した酸性
水溶液のｐＨを水酸化アンモニウムを用いて１．０に調
整し、実施例１と同様の電解処理、塗装を行い、耐食性
試験を実施した。結果を表１に示す。Example 5 The pH of an acidic aqueous solution obtained by adding hexavalent chromium ion to chromic anhydride at 50 g / l, sulfate ion to sulfuric acid at 1 g / l, and zircon hydrofluoric acid to 400 ppm of fluorine was adjusted using ammonium hydroxide. And the same electrolytic treatment and coating as in Example 1 were performed, and a corrosion resistance test was performed. Table 1 shows the results.
【００２３】（実施例６）６価クロムイオンを無水クロ
ム酸で２０ｇ／ｌ、硫酸イオンを硫酸で４００ｐｐｍ、
フッ化水素酸でフッ素を１１０ｐｐｍとなるように添加
した酸性水溶液を水酸化アンモニウムを用いてｐＨ１．
０に調整し、実施例１と同様の電解処理、塗装を行い、
耐食性試験を実施した。ただし、通電時の電流密度を１
０Ａ／ｄｍ2とし電解時間を１０秒とした。結果を表２
に示す。Example 6 Hexavalent chromium ions were 20 g / l with chromic anhydride and sulfate ions were 400 ppm with sulfuric acid.
An acidic aqueous solution to which fluorine was added to be 110 ppm with hydrofluoric acid was used to adjust the pH to 1.0 using ammonium hydroxide.
0, and the same electrolytic treatment and coating as in Example 1 were performed.
A corrosion resistance test was performed. However, when the current density during energization is 1
The electrolysis time was 10 seconds at 0 A / dm 2 . Table 2 shows the results
Shown in
【００２４】（比較例４）６価クロムイオンを無水クロ
ム酸で２０ｇ／ｌ、硫酸イオンを硫酸で４００ｐｐｍ、
フッ化水素酸でフッ素を１１０ｐｐｍとなるように添加
した酸性水溶液を水酸化アンモニウムを用いてｐＨ１．
０に調整し、実施例１と同様の電解処理、塗装を行い、
耐食性試験を実施した。ただし、通電時の電流密度を２
０Ａ／ｄｍ2とし電解時間を１０秒とした。結果を表２
に示す。Comparative Example 4 Hexavalent chromium ions were 20 g / l with chromic anhydride, sulfate ions were 400 ppm with sulfuric acid,
An acidic aqueous solution to which fluorine was added to be 110 ppm with hydrofluoric acid was used to adjust the pH to 1.0 using ammonium hydroxide.
0, and the same electrolytic treatment and coating as in Example 1 were performed.
A corrosion resistance test was performed. However, when the current density during energization is 2
The electrolysis time was 10 seconds at 0 A / dm 2 . Table 2 shows the results
Shown in
【００２５】（実施例７）長さ方向が実際のアルミホイ
ール直径を想定したアルミニウム鋳造合金（ＪＩＳ記号
ＡＣ４Ｃ，サイズ７０×４５０×７ｍ／ｍ）板を用意
し、実施例２と同条件の酸性水溶液中（ｐＨ１．０）
に、長さ方向４５０ｍｍが６０秒間で全没する入槽速度
で入槽した。試験板が全没してから電流密度２Ａ／ｄｍ
2で３０秒間陰極電解し、さらに通電終了後に前記酸性
水溶液中にて５秒間保持してから試験板を取り出し水洗
および脱イオン水洗浄を行った後１００℃の乾燥炉で５
分間乾燥した。このように作製された試験板の上方の１
００ｍｍ分と下方の１００ｍｍ分を切断し、それぞれ別
々に熱硬化型アクリル樹脂クリヤーを塗装し（膜厚３０
μ）１４０℃で３０分焼付け乾燥後、耐食性試験（糸錆
試験、塩水噴霧試験）を実施した。結果を表３に示す。(Example 7) An aluminum cast alloy (JIS symbol AC4C, size 70 × 450 × 7 m / m) plate was prepared assuming the actual aluminum wheel diameter in the length direction, and acidity under the same conditions as in Example 2 was prepared. In aqueous solution (pH 1.0)
Then, the tank was introduced at a tank entry speed in which the lengthwise direction of 450 mm was completely submerged in 60 seconds. Current density 2A / dm after the test plate is completely immersed
Cathodic electrolysis at 2 for 30 seconds, and after completion of energization, holding in the acidic aqueous solution for 5 seconds, removing the test plate, washing with water and washing with deionized water, and drying in a drying oven at 100 ° C.
Dried for minutes. The upper part of the test plate thus prepared
00 mm and the lower 100 mm were cut, and each was separately coated with a thermosetting acrylic resin clear (film thickness 30 mm).
μ) After baking and drying at 140 ° C. for 30 minutes, a corrosion resistance test (yarn rust test, salt spray test) was performed. Table 3 shows the results.
【００２６】（比較例５）長さ方向が実際のアルミホイ
ール直径を想定したアルミニウム鋳造合金（ＪＩＳ記号
ＡＣ４Ｃ、サイズ７０×４５０×７ｍ／ｍ）板を用意
し、６．３Ａの定電流電解条件（全没状態で電流密度２
Ａ／ｄｍ2となる条件）で実施例２と同条件の酸性水溶
液中（ｐＨ１．０）に、長さ方向４５０ｍｍが６０秒間
で全没する入槽速度で通電入槽した。全没後３０秒間通
電し、さらに通電終了後に前記酸性水溶液中にて５秒間
保持してから試験板を取り出し水洗および脱イオン水洗
浄を行った後１００℃の乾燥炉で５分間乾燥した。この
ように作製された試験板の上方の１００ｍｍ分と下方の
１００ｍｍ分を切断し、それぞれ別々に熱硬化型アクリ
ル樹脂クリヤーを塗装し（膜厚３０μ）１４０℃で３０
分焼付け乾燥後、耐食性試験（糸錆試験、塩水噴霧試
験）を実施した。結果を表３に示す。(Comparative Example 5) An aluminum cast alloy (JIS symbol AC4C, size 70 × 450 × 7 m / m) plate whose length direction is assumed to be the actual aluminum wheel diameter was prepared, and a constant current electrolytic condition of 6.3 A was prepared. (Current density 2
A / dm 2 ) was supplied in an acidic aqueous solution (pH 1.0) under the same conditions as in Example 2 at a bathing speed at which 450 mm in the length direction completely submerged in 60 seconds. After immersion, the battery was energized for 30 seconds. After the energization was completed, the test plate was kept in the acidic aqueous solution for 5 seconds. A 100 mm upper portion and a lower 100 mm portion of the test plate thus prepared were cut, and each was separately coated with a thermosetting acrylic resin clear (thickness: 30 μm) at 140 ° C.
After partial baking and drying, a corrosion resistance test (yarn rust test, salt spray test) was performed. Table 3 shows the results.
【００２７】（実施例８）実施例２と同条件の酸性処理
液中（ｐＨ１．０）に試験板を浸漬後、通電を開始し電
流密度２Ａ／ｄｍ2で３０秒間陰極電解した。通電終了
後１秒間前記酸性水溶液中に保持し、試験板を取り出し
水洗および脱イオン水洗浄を行った後１００℃の乾燥炉
で５分間乾燥した。次に、実施例２と同様に塗装し耐食
性試験（糸錆試験、塩水噴霧試験）を実施した。結果を
表３に示す。(Example 8) After immersing the test plate in an acidic treatment solution (pH 1.0) under the same conditions as in Example 2, energization was started and cathodic electrolysis was performed at a current density of 2 A / dm 2 for 30 seconds. After the completion of energization, the sample was kept in the acidic aqueous solution for 1 second, the test plate was taken out, washed with water and deionized water, and then dried in a drying oven at 100 ° C. for 5 minutes. Next, the coating was performed in the same manner as in Example 2, and a corrosion resistance test (fiber rust test, salt spray test) was performed. Table 3 shows the results.
【００２８】（実施例９）実施例２と同条件の酸性処理
液中（ｐＨ１．０）に試験板を浸漬後、通電を開始し電
流密度２Ａ／ｄｍ2で３０秒間陰極電解した。通電終了
後１８０秒間前記酸性水溶液中に保持し、試験板を取り
出し水洗および脱イオン水洗浄を行った後１００℃の乾
燥炉で５分間乾燥した。次に、実施例２と同様に塗装し
耐食性試験（糸錆試験、塩水噴霧試験）を実施した。結
果を表３に示す。Example 9 After the test plate was immersed in an acidic treatment solution (pH 1.0) under the same conditions as in Example 2, energization was started and cathodic electrolysis was performed at a current density of 2 A / dm 2 for 30 seconds. After the energization was completed, the sample was held in the acidic aqueous solution for 180 seconds, the test plate was taken out, washed with water and deionized water, and then dried in a drying oven at 100 ° C. for 5 minutes. Next, the coating was performed in the same manner as in Example 2, and a corrosion resistance test (fiber rust test, salt spray test) was performed. Table 3 shows the results.
【００２９】（実施例１０）実施例２と同条件の酸性処
理液中（ｐＨ１．０）に試験板を浸漬後、通電を開始し
電流密度２Ａ／ｄｍ2で３０秒間陰極電解した。通電終
了後３００秒間前記酸性水溶液中に保持し、試験板を取
り出し水洗および脱イオン水洗浄を行った後１００℃の
乾燥炉で５分間乾燥した。次に、実施例２と同様に塗装
し耐食性試験（糸錆試験、塩水噴霧試験）を実施した。
結果を表３に示す。Example 10 A test plate was immersed in an acidic treatment solution (pH 1.0) under the same conditions as in Example 2, and then current was started and cathodic electrolysis was performed at a current density of 2 A / dm 2 for 30 seconds. After the energization was completed, the plate was kept in the acidic aqueous solution for 300 seconds, the test plate was taken out, washed with water and deionized water, and then dried in a drying oven at 100 ° C. for 5 minutes. Next, the coating was performed in the same manner as in Example 2, and a corrosion resistance test (fiber rust test, salt spray test) was performed.
Table 3 shows the results.
【００３０】（比較例６）実施例２と同条件の酸性処理
液中（ｐＨ１．０）に試験板を浸漬後、通電を開始し電
流密度２Ａ／ｄｍ2で３０秒間陰極電解した。通電終了
後３６０秒間前記酸性水溶液中に保持し、試験板を取り
出し水洗および脱イオン水洗浄を行った後１００℃の乾
燥炉で５分間乾燥した。次に、実施例２と同様に塗装し
耐食性試験（糸錆試験、塩水噴霧試験）を実施した。結
果を表３に示す。(Comparative Example 6) After immersing the test plate in an acidic treatment solution (pH 1.0) under the same conditions as in Example 2, the current was started and the cathodic electrolysis was performed at a current density of 2 A / dm 2 for 30 seconds. After the energization was completed, the plate was kept in the aqueous acidic solution for 360 seconds, the test plate was taken out, washed with water and deionized water, and then dried in a drying oven at 100 ° C. for 5 minutes. Next, the coating was performed in the same manner as in Example 2, and a corrosion resistance test (fiber rust test, salt spray test) was performed. Table 3 shows the results.
【００３１】（比較例７）実施例２と同条件の酸性処理
液中（ｐＨ１．０）に試験板を浸漬後、通電を開始し電
流密度２Ａ／ｄｍ2で３０秒間陰極電解した。通電終了
時通電したまま試験板を取り出し水洗および脱イオン水
洗浄を行った後１００℃の乾燥炉で５分間乾燥した。次
に、実施例２と同様に塗装し耐食性試験（糸錆試験、塩
水噴霧試験）を実施した。結果を表３に示す。(Comparative Example 7) After immersing the test plate in an acidic treatment solution (pH 1.0) under the same conditions as in Example 2, energization was started and cathodic electrolysis was performed at a current density of 2 A / dm 2 for 30 seconds. At the end of energization, the test plate was taken out with energization, washed with water and deionized water, and dried in a drying oven at 100 ° C. for 5 minutes. Next, the coating was performed in the same manner as in Example 2, and a corrosion resistance test (fiber rust test, salt spray test) was performed. Table 3 shows the results.
【００３２】（比較例８）試験板をアルカリ脱脂洗浄し
て表面を清浄にした後、反応型クロメート処理（日本パ
ーカライジング製アルクロム３７０３使用）し、水洗及
び純水洗浄を行った後１００℃の乾燥炉で５分間乾燥し
た。次に試験板に熱硬化型アクリル樹脂クリヤーを塗装
し（膜厚３０μ）１４０℃３０分焼付け乾燥後、耐食性
試験（糸錆試験、塩水噴霧試験）を実施した。結果を表
３に示す。(Comparative Example 8) A test plate was cleaned by alkali degreasing to clean the surface, then subjected to a reactive chromate treatment (using Alchrome 3703 manufactured by Nippon Parkerizing), washed with water and pure water, and then dried at 100 ° C. Dry in oven for 5 minutes. Next, a thermosetting acrylic resin clear was applied to the test plate (thickness: 30 μm), baked and dried at 140 ° C. for 30 minutes, and then subjected to a corrosion resistance test (fiber rust test, salt spray test). Table 3 shows the results.
【００３３】（比較例９）試験板をアルカリ脱脂洗浄、
苛性ソーダエッチング、デスマット処理して表面を清浄
にした後、一般的に使用されているアルマイト処理（硫
酸１８０ｇ／ｌ、溶存アルミニウム５ｇ／ｌ、浴温２５
℃、電流密度１Ａ／ｄｍ2の条件で１５分間陽極酸化処
理を行う）し、水洗及び純水洗浄を行った後１００℃の
乾燥炉で５分間乾燥した。次に試験板に熱硬化型アクリ
ル樹脂クリヤーを塗装し（膜厚３０μ）１４０℃３０分
焼付け乾燥後、耐食性試験（糸錆試験、塩水噴霧試験）
を実施した。結果を表３に示す。(Comparative Example 9) A test plate was subjected to alkaline degreasing and washing,
After the surface is cleaned by caustic soda etching and desmutting, alumite treatment (180 g / l sulfuric acid, 5 g / l dissolved aluminum, bath temperature 25) is used.
Anodizing treatment was performed for 15 minutes at a temperature of 1 ° C. and a current density of 1 A / dm 2 ), followed by washing with water and pure water, followed by drying in a drying oven at 100 ° C. for 5 minutes. Next, a thermosetting acrylic resin clear was applied to the test plate (thickness: 30 μm), baked at 140 ° C. for 30 minutes, dried, and then subjected to a corrosion resistance test (yarn rust test, salt spray test).
Was carried out. Table 3 shows the results.
【００３４】（比較例９）試験板をアルカリ脱脂洗浄し
て表面を清浄にした後、１００℃の乾燥炉で５分間乾燥
した。次に試験板に熱硬化型アクリル樹脂クリヤーを塗
装し（膜厚３０μ）１４０℃３０分焼付け乾燥後、耐食
性試験（糸錆試験、塩水噴霧試験）を実施した。結果を
表３に示す。Comparative Example 9 A test plate was cleaned by alkali degreasing to clean the surface, and then dried in a drying oven at 100 ° C. for 5 minutes. Next, a thermosetting acrylic resin clear was applied to the test plate (thickness: 30 μm), baked and dried at 140 ° C. for 30 minutes, and then subjected to a corrosion resistance test (fiber rust test, salt spray test). Table 3 shows the results.
【００３５】（評価試験方法） １）皮膜外観 無処理サンプルを基準として色差計によりＪＩＳ−Ｚ８
７３０に規定されている色差を測定して下記のランクに
分けて評価した。 ◎ 色差 ０〜３．２ （目視では変色が確認され
ず） ○ 色差 ３．２〜６．５ （僅かに変色が認められ
る） △ 色差 ６．５〜１３ （明らかに変色が認められ
る） × 色差 １３以上 （強く変色が認められる）(Evaluation test method) 1) Appearance of coating film JIS-Z8 using a color difference meter based on an untreated sample.
The color difference specified in 730 was measured and evaluated according to the following ranks. ◎ Color difference 0 to 3.2 (discoloration is not visually observed) ○ Color difference 3.2 to 6.5 (slight discoloration is observed) △ Color difference 6.5 to 13 (discoloration is clearly observed) × color difference 13 or more (strong discoloration is observed)
【００３６】２）クロム付着量 蛍光Ｘ線分析装置により測定。2) Chromium adhering amount Measured by a fluorescent X-ray analyzer.
【００３７】３）糸錆試験 塗装した試験板にＮＴカッターで素地まで達するカット
傷をつけた後、腐食液（１規定塩酸と５％過酸化水素水
の混液）に１分浸漬後常温で乾燥し２４時間経時する。
湿潤試験（温度５０℃、湿度８０％）を１０００時間行
った後、カット傷より発生した糸錆の長さを測定する。 ◎ 最大糸錆長さ２ｍｍ以内 ○ 〃 ３ｍｍ以内 △ 〃 ５ｍｍ以内 × 〃 ５ｍｍ以上3) Yarn rust test A coated test plate was cut with an NT cutter to reach the substrate, immersed in a corrosive solution (a mixture of 1N hydrochloric acid and 5% hydrogen peroxide solution) for 1 minute, and dried at room temperature. And let it stand for 24 hours.
After performing a wet test (temperature of 50 ° C., humidity of 80%) for 1000 hours, the length of the thread rust generated from the cut scratch is measured. ◎ Maximum rust length 2mm or less ○ 〃 3mm or less △ 以内 5mm or less × ５ 5mm or more
【００３８】４）塩水噴霧試験（ＳＳＴ） 塗装した試験板にＮＴカッターで素地まで達するカット
傷をつけた後、ＪＩＳ−Ｚ２３７１に基いて１０００時
間行った後、カット傷からの錆やフクレの最大幅を測定
する。 ◎ 最大フクレ錆幅１ｍｍ以内 ○ 〃 ２ｍｍ以内 △ 〃 ３ｍｍ以内 × 〃 ３ｍｍ以上4) Salt Spray Test (SST) After making a cut on the coated test plate to reach the substrate with an NT cutter, performing the test for 1000 hours in accordance with JIS-Z2371, and then examining rust and blistering from the cut. Measure significant. ◎ Maximum blister rust width 1mm or less ○ 以内 2mm or less △ 以内 3mm or less × ３ 3mm or more
【００３９】実施例および比較例から次のことが言え
る。 表１（酸性水溶液の組成）、表２（陰極電解電流密
度）、表３（処理方法）から明らかなように本発明の実
施例１〜１０においては、外観および塗装後耐食性（耐
糸錆性、耐塩水噴霧性）ともに優れている。 一方、本発明の範囲外である比較例１〜４、６並びに
従来塗装下地処理法である反応型クロメートを用いた比
較例８、、アルマイトを用いた比較例９、アルカリ脱脂
のみを用いた比較例１０では、外観および塗装後耐食性
ともに良好なものはなかった。 また、比較例５のように通電状態で入槽したものは試
験板の上下で皮膜量が異なり、不均一な外観となって好
ましくなかった。 また、比較例７のように通電状態で出槽したものは外
観が悪く、また塗装後の耐食性も良くなかった。The following can be said from the examples and comparative examples. As is clear from Table 1 (composition of acidic aqueous solution), Table 2 (cathode electrolysis current density), and Table 3 (treatment method), in Examples 1 to 10 of the present invention, appearance and corrosion resistance after painting (fiber rust resistance) And salt spray resistance). On the other hand, Comparative Examples 1 to 4 and 6 which are out of the scope of the present invention, Comparative Example 8 using a reactive type chromate which is a conventional coating undercoating method, Comparative Example 9 using alumite, and a comparison using only alkali degreasing In Example 10, none was good in both appearance and corrosion resistance after painting. In the case where the tank was energized as in Comparative Example 5, the amount of the film was different between the upper and lower portions of the test plate, resulting in an uneven appearance, which was not preferable. In addition, as shown in Comparative Example 7, the one which was discharged from the tank in an energized state had a poor appearance and had poor corrosion resistance after painting.
【００４０】[0040]
【発明の効果】本発明によれば、アルミホイール素材の
光輝性を保持し、かつ塗装後耐食性、密着性に優れた無
色クロメート皮膜を形成させることができ、クリヤー塗
装前処理として、従来問題となっていた耐食性、特に耐
糸錆性を向上させることができる。According to the present invention, it is possible to form a colorless chromate film which retains the brilliancy of the aluminum wheel material and has excellent corrosion resistance and adhesion after coating, and has a problem as a conventional pretreatment for clear coating. The corrosion resistance, especially the thread rust resistance, which has been improved, can be improved.
【００４１】[0041]
【表１】 [Table 1]
【００４２】[0042]
【表２】 [Table 2]
【００４３】[0043]
【表３】 [Table 3]
───────────────────────────────────────────────────── フロントページの続き (72)発明者 長谷部 昭彦 東京都中央区日本橋１丁目15番１号 日 本パーカライジング株式会社内 (72)発明者 畑野 憲文 東京都中央区日本橋１丁目15番１号 日 本パーカライジング株式会社内 (56)参考文献 特開 平５−179488（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C25D 11/38 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akihiko Hasebe 1-15-1 Nihonbashi, Chuo-ku, Tokyo Inside Japan Parkerizing Co., Ltd. (72) Inventor Norifumi Hatano 1-15-1 Nihonbashi, Chuo-ku, Tokyo Sun (56) References JP-A-5-179488 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) C25D 11/38
Claims (1)
ｌ以上、硫酸イオン２０〜２０００ｐｐｍ及びフッ素１
０〜４００ｐｐｍを含有するｐＨ０．６〜１．７の酸性
水溶液中に浸漬し、該アルミホイールが該酸性水溶液中
に全没してから０．５〜１５Ａ／ｄｍ2の電流密度で４
秒以上陰極電解処理し、通電終了後、通電を停止した状
態で１〜３００秒間該酸性水溶液中にて保持した後、該
酸性水溶液から取り出すことを特徴とするアルミホイー
ルの無色クロメート皮膜形成方法。。1. An aluminum wheel is made of hexavalent chromium ion 2 g /
l or more, sulfate ion 20 to 2000 ppm and fluorine 1
The aluminum wheel was immersed in an acidic aqueous solution having a pH of 0.6 to 1.7 containing 0 to 400 ppm, and then immersed in the acidic aqueous solution at a current density of 0.5 to 15 A / dm 2.
Sec cathodic electrolysis treatment, after application end, like stopping the energization
A method for forming a colorless chromate film on an aluminum wheel, wherein the colorless chromate film is held in the acidic aqueous solution for 1 to 300 seconds and then taken out of the acidic aqueous solution. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17993293A JP3224639B2 (en) | 1993-06-25 | 1993-06-25 | Method for forming colorless chromate film on aluminum wheels |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17993293A JP3224639B2 (en) | 1993-06-25 | 1993-06-25 | Method for forming colorless chromate film on aluminum wheels |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0711494A JPH0711494A (en) | 1995-01-13 |
| JP3224639B2 true JP3224639B2 (en) | 2001-11-05 |
Family
ID=16074457
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17993293A Expired - Fee Related JP3224639B2 (en) | 1993-06-25 | 1993-06-25 | Method for forming colorless chromate film on aluminum wheels |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3224639B2 (en) |
-
1993
- 1993-06-25 JP JP17993293A patent/JP3224639B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0711494A (en) | 1995-01-13 |
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