JPH06293995A - Treatment before coating aluminum based metal surface with water based inorganic coating material - Google Patents
Treatment before coating aluminum based metal surface with water based inorganic coating materialInfo
- Publication number
- JPH06293995A JPH06293995A JP10512593A JP10512593A JPH06293995A JP H06293995 A JPH06293995 A JP H06293995A JP 10512593 A JP10512593 A JP 10512593A JP 10512593 A JP10512593 A JP 10512593A JP H06293995 A JPH06293995 A JP H06293995A
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- Prior art keywords
- coating
- treatment
- film
- chromium
- based inorganic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Application Of Or Painting With Fluid Materials (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明はアルミニウム系金属表面
に水系無機塗料、例えばアルカリ珪酸塩系無機塗料を塗
装する場合の新規な塗装前処理方法に関する。より具体
的には陰極電解法により該素材表面に金属クロムと３価
のクロムを主成分とするクロム化合物の皮膜（以下、ク
ロメート皮膜と称する）を形成させる方法に関するもの
であって、前記前処理した表面に水系無機塗料を塗装し
て、ブツ、フクレ、ワレ、並びに剥離等の塗膜欠陥がな
く、かつ塗装後の密着性、ならびに耐食性の優れた高品
質塗膜を安定的に形成させ得る新規な水系無機塗料塗装
前処理方法を提供するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel pretreatment method for coating an aluminum-based metal surface with a water-based inorganic coating material such as an alkali silicate-based inorganic coating material. More specifically, it relates to a method of forming a film of a chromium compound containing metal chromium and trivalent chromium as main components (hereinafter referred to as a chromate film) on the surface of the material by a cathodic electrolysis method, wherein the pretreatment It is possible to apply a water-based inorganic coating on the coated surface to form a high-quality coating that has no coating defects such as spots, blisters, cracks, and peeling, and has excellent adhesion and corrosion resistance after coating. The present invention provides a novel pretreatment method for coating water-based inorganic paint.
【０００２】[0002]
【従来技術】アルカリ珪酸塩系セラミックコーティング
剤を初めとする水系無機塗料は、その高い耐食性、耐薬
品性、耐摩耗性、耐候性、耐熱性、耐カビ性、防菌性さ
らには従来の有機樹脂系塗料の塗膜外観とは趣を異にし
た意匠性から、建材や構造材の分野で大きな注目を集め
いている。特に同じような耐候性、耐摩耗性、耐食性、
耐薬品性を目的として注目を集めいているフッ素樹脂塗
料に比べてコスト的に安価で、かつ同等の性能を有して
いる。しかも、形成される塗膜はガラス質なため有機樹
脂系の塗膜に比べ著しく高い塗膜硬度を有するために、
比較的軟質な金属表面を高硬度に改質し、耐傷付き性を
著しく向上することによって恒久的な意匠性を提供する
ことができる。2. Description of the Related Art Water-based inorganic paints such as alkali silicate ceramic coating agents have high corrosion resistance, chemical resistance, abrasion resistance, weather resistance, heat resistance, mold resistance, antibacterial properties, and even conventional organic coatings. Due to its design, which is different from the appearance of the coating film of resin-based paints, it has received a great deal of attention in the fields of building materials and structural materials. Especially similar weather resistance, wear resistance, corrosion resistance,
Compared with fluororesin paints, which are drawing attention for the purpose of chemical resistance, they are cheaper in cost and have the same performance. Moreover, since the coating film formed is glassy, it has significantly higher coating hardness than organic resin coating films,
A relatively soft metal surface is modified to have a high hardness and scratch resistance is remarkably improved, so that a permanent design property can be provided.
【０００３】しかし、これらの水系無機塗料はｐＨが高
く強アルカリ性を呈するために、両性金属であるアルミ
ニウムのようにアルカリに浸されやすい素材に塗装する
と、塗装直後から金属溶出が始まり、続く焼付け工程に
おいてブツ、フクレ、剥離等に代表される塗装欠陥を生
ずることになる。これを避けるために、塗装前処理とし
てアルミニウム又はアルミニウム合金素材に対しては反
応型、もしくは塗布型クロメート処理や陽極酸化処理
（アルマイト処理）が施される。However, since these water-based inorganic paints have a high pH and a strong alkalinity, when they are applied to a material such as aluminum, which is an amphoteric metal, which is easily immersed in an alkali, metal elution starts immediately after the application and the subsequent baking step. In this case, coating defects such as swelling, blistering and peeling will occur. In order to avoid this, a reactive or coating type chromate treatment or anodizing treatment (alumite treatment) is applied to the aluminum or aluminum alloy material as a pretreatment for coating.
【０００４】これら従来の前処理方法は、きわめて注意
深く完璧に処理された場合には問題無いが、処理上予想
される僅かな欠陥や搬送時に傷等がつけられるとその部
分が集中的に侵され、先述の塗装外観不良の原因とな
る。しかも、クロメート処理においては皮膜そのものも
充分満足な耐アルカリ性を有しているわけではないの
で、その対応手段として前記皮膜形成後その表面を２０
０℃以上の温度で２０〜３０分間程度の空焼きが必要で
あり、従って生産効率を低下させる問題を有している。
一方、アルミニウム素材を対象として行われる陽極酸化
処理はクロメート処理等に比べると皮膜付着量が大きい
ためにこれらの欠陥が起こりにくいものの、通常長くと
も６０秒間以内で処理可能なクロメート処理に比較し、
数１０分間程度の長い処理時間を必要とし、この方法も
生産効率が悪い。また、通常陽極酸化処理はそのままで
はポーラスなため封孔処理が施されるが、この封孔処理
後の水系無機塗料塗膜においては、有機樹脂系塗料によ
る塗装の場合とは異なり逆に塗膜剥離等の塗膜欠陥が発
生しやすい。従って、陽極酸化皮膜に該水系無機塗料を
塗装するためには未封孔の状態で塗装しなければならな
いが、未封孔の陽極酸化皮膜は不安定なため、処理後の
経過時間が長いと表面状態が変化して封孔処理を行った
場合と同様な塗装欠陥を生じやすく、陽極酸化処理後直
ちに塗装しなければならないといった工程上の制約を受
ける。These conventional pretreatment methods have no problem when they are treated extremely carefully and completely, but if a slight defect expected in the treatment or a flaw during transportation is attached, the portion is intensively attacked. It causes the above-mentioned poor coating appearance. Moreover, in the chromate treatment, the film itself does not have sufficiently satisfactory alkali resistance, so as a countermeasure against this, the surface of the film after the film formation is 20
Baking at a temperature of 0 ° C. or higher for about 20 to 30 minutes is required, and thus there is a problem of lowering production efficiency.
On the other hand, the anodizing treatment performed on the aluminum material is less likely to cause these defects because the amount of coating adhered is larger than that of the chromate treatment or the like, but as compared with the chromate treatment which can usually be treated within 60 seconds at the longest,
A long processing time of about several tens of minutes is required, and this method also has poor production efficiency. In addition, since the anodizing treatment is usually porous as it is, it is subjected to a sealing treatment.However, in the water-based inorganic paint coating film after this sealing treatment, unlike the case of coating with an organic resin paint, the coating film is reversed. Coating film defects such as peeling are likely to occur. Therefore, in order to coat the water-based inorganic coating on the anodic oxide coating, it must be coated in an unsealed state, but the unsealed anodic oxide coating is unstable, so that the elapsed time after treatment is long. Similar to the case where the surface condition is changed and the sealing treatment is performed, coating defects are likely to occur, and there is a process restriction that coating is required immediately after the anodizing treatment.
【０００５】以上、アルミニウム系金属表面に水系無機
塗料を塗装する場合の塗装前処理方法に関する従来技術
について概説したが、金属材料の種類によっては上に述
べた方法を充分注意深く適用しても従来の方法では良好
な塗膜形成が不可能なものもある。例えば、アルミダイ
キャストに広く用いられているアルミニウム合金ＡＤＣ
シリーズ（ＪＩＳ）が挙げられ、これらは他のアルミニ
ウム合金に比較して合金元素の添加量が多く、一般に耐
腐食性が良好とはいえないとされている。特にＡＤＣ１
２種の材料では上に述べたどの塗装前処理方法でも塗膜
焼付け時に鋳込みの際に形成される巣孔部分からフク
レ、ブツが生じたり、剥離が生じたりして良好な塗装が
不可能とされている。 反応型、塗布型クロメート皮膜は均一な皮膜が得られ
るもののＣｒとして５０ｍｇ／ｍ2程度と皮膜量が比較
的少なく、しかも耐アルカリ性に劣ること、陽極酸化
皮膜においては５μｍ程度と厚膜ではあるが傷等がつく
とむしろそこが集中的に侵されること、さらには、封
孔処理を行っていないことから、経時安定性に劣ること
等が欠点として挙げられる。従って、これらを解決する
ための前処理皮膜は耐アルカリ性が優れることと、皮膜
に傷等の欠陥があってもその部分が集中的に腐食される
ことがなくむしろ緩和する方向に働くような皮膜である
ことが望まれる。The prior art relating to the pretreatment method for coating water-based inorganic paint on the surface of an aluminum-based metal has been outlined above. However, depending on the type of metal material, even if the above-mentioned method is applied with sufficient caution, the conventional method will be used. In some cases, good film formation cannot be achieved by the method. For example, aluminum alloy ADC widely used for aluminum die casting
The series (JIS) is mentioned, and the addition amount of alloy elements is larger than those of other aluminum alloys, and it is generally said that the corrosion resistance is not good. Especially ADC1
With the two types of materials, any of the above-mentioned pretreatment methods for coating make it impossible to achieve good coating due to blisters, spots, and peeling from the holes formed during casting when baking the coating film. Has been done. Although a reactive or coating type chromate film can obtain a uniform film, the amount of Cr is about 50 mg / m 2 and the amount of the film is relatively small, and the alkali resistance is poor, and the anodized film is about 5 μm, which is a thick film. If scratches or the like are formed, they are rather invaded more intensively, and further, because the sealing treatment is not performed, the stability over time is inferior. Therefore, the pretreatment film for solving these is excellent in alkali resistance, and even if there are defects such as scratches on the film, the part is not corroded intensively but rather acts to relax Is desired.
【０００６】[0006]
【発明が解決しようとする課題】本発明の目的はアルミ
ニウム系金属材料の表面に水系無機塗料を塗装して、塗
装外観に優れ、かつ密着性、耐食性の優れた塗膜を形成
させることができる新規な水系無機塗料塗装前処理方法
を提供しようとするものである。The object of the present invention is to coat a surface of an aluminum-based metal material with a water-based inorganic coating material to form a coating film having excellent coating appearance, adhesion and corrosion resistance. It is intended to provide a new pretreatment method for coating an aqueous inorganic paint.
【０００７】[0007]
【課題を解決するための手段】本発明者らは上述の機能
を付与するための表面処理方法について鋭意検討を重ね
た結果、６価クロムイオン及び／又は３価のクロムイオ
ンを含有する溶液中で被処理物を陰極電解処理をするこ
とにより得られる皮膜が水系無機塗料の塗装下地として
最適であることを見いだし本発明を完成させた。Means for Solving the Problems The inventors of the present invention have conducted extensive studies as to a surface treatment method for imparting the above-mentioned function, and as a result, in a solution containing hexavalent chromium ions and / or trivalent chromium ions. The present invention has been completed by finding that the film obtained by subjecting the object to be treated to cathodic electrolysis is optimum as a coating base for the water-based inorganic paint.
【０００８】すなわち、本発明は、アルミニウム系金属
表面に水系無機塗料を塗装する場合の該塗装前処理にお
いて、該金属表面を予め６価クロムイオン及び／又は３
価クロムイオンを含有する酸性水溶液にて陰極電解処理
をすることを特徴とする、アルミニウム系金属表面の水
系無機塗料塗装前処理方法を提供する。That is, according to the present invention, when the water-based inorganic paint is applied to the surface of an aluminum-based metal, the metal surface is preliminarily treated with hexavalent chromium ions and / or 3 in the pretreatment of the coating.
Provided is a method for pretreatment of a water-based inorganic paint coating on an aluminum-based metal surface, which comprises subjecting a cathodic electrolysis treatment to an acidic aqueous solution containing valent chromium ions.
【０００９】以下本発明の構成を詳述する。本発明で対
象とする金属は、アルミニウム系金属である。さらに詳
しくは、アルミニウム、アルミニウム合金、アルミニウ
ムめっき材、アルミニウム合金めっき材である。The structure of the present invention will be described in detail below. The metal targeted by the present invention is an aluminum-based metal. More specifically, they are aluminum, aluminum alloys, aluminum plated materials, and aluminum alloy plated materials.
【００１０】最初に６価クロムイオンを含む溶液により
陰極電解処理をする場合について説明する。このような
電解液では処理を継続すると皮膜として生成される３価
クロムを主体とするクロメート皮膜の一部が溶解して浴
中に３価クロムイオンが蓄積するため、結局この例は６
価と３価のクロムイオンが混在する場合についても同時
に論じられることになる。First, the case of performing cathodic electrolysis treatment with a solution containing hexavalent chromium ions will be described. In such an electrolytic solution, when the treatment is continued, a part of the chromate film mainly composed of trivalent chromium, which is formed as a film, is dissolved and trivalent chromium ions are accumulated in the bath.
The case where valence and trivalent chromium ions are mixed will be discussed at the same time.
【００１１】使用する電解液は６価クロムを含有する通
常のクロムめっき浴を若干修正して用いればよく、とく
に大きな限定条件はない。最も代表的なクロムめっき浴
にはサージェント浴（無水クロム酸：２００〜３００ｇ
／Ｌ、硫酸：２〜３ｇ／Ｌ）やサージェント浴の硫酸を
一部硅フッ化浴等があるが、本発明では通常のクロムめ
っきのように数μｍ〜数１０μｍの連続的な金属クロム
皮膜で素材表面を完全に被覆する必要は無いので、通常
のクロムめっき浴のように高濃度のものを用いる必要は
ない。経験上、無水クロム酸を用いて６価クロム換算で
２ｇ／Ｌ以上あれば充分で、特に、６価クロムの排水処
理の問題を考慮すると希薄な溶液を用いた方が工業的に
も有利である。ただし、サージェント浴においては無水
クロム酸／硫酸の比率が１００／１となっているが、希
釈された溶液においてもこの比率で硫酸を添加した方が
皮膜形成効率上好ましい結果となっている。The electrolytic solution to be used may be an ordinary chromium plating bath containing hexavalent chromium with a slight modification, and there is no particular limiting condition. The most typical chrome plating bath is the Sargent bath (chromic anhydride: 200-300 g
/ L, sulfuric acid: 2 to 3 g / L) or sulfuric acid in a Sargent bath is partially fluorinated, but in the present invention, a continuous metallic chromium film of several μm to several tens of μm like ordinary chromium plating. Since it is not necessary to completely cover the surface of the raw material, it is not necessary to use a high-concentration bath like the usual chromium plating bath. From experience, it is sufficient to use chromic anhydride in an amount of 2 g / L or more in terms of hexavalent chromium. Especially, considering the problem of wastewater treatment of hexavalent chromium, it is industrially advantageous to use a dilute solution. is there. However, although the ratio of chromic anhydride / sulfuric acid is 100/1 in the Sargent bath, it is preferable to add sulfuric acid in this ratio even in a diluted solution in terms of film formation efficiency.
【００１２】一方、電解条件についてもとくに大きな制
約はなく、温度については常温でも可能であるが、電解
条件を一定にする意味でも４０℃程度で管理するのが好
ましい。電流密度については、０．５〜６０Ａ／ｄｍ2
と広い範囲で可能であるが、必要な全クロム付着量は電
流密度と電解時間によってきまるので、それらを適性範
囲内にするためには電流密度１〜２Ａ／ｄｍ2程度、電
解時間は３０〜１００秒程度とすべきである。前にも述
べたように、このような低電流密度かつ短時間の電解は
通常のクロムめっきやアルミニウムの陽極酸化処理と比
較して電源設備コスト、ランニングコストの点でも非常
に有利と思われる。また、使用する陽極（対電極）は
鉛、酸化鉛（触媒電極）、あるいは炭素のような不溶性
電極が好ましいが、鉄やステンレスでも可能で、この場
合溶出する鉄・ニッケル等のイオンは数ｇ／Ｌまでは許
容可能である。ステンレスを陽極として用いた場合はク
ロム（３価）の溶出も起こり得るが、３価のクロムイオ
ンはカソードにおいて金属クロムが析出する過程でも生
成し浴中に蓄積する。一方、アニオンとして酸化性の酸
となる硝酸イオンや３価クロムイオンとの溶解度積の小
さいりん酸イオンなどは皮膜の形成効率を低下させるた
めに、不純物としての混入を避けるべきである。また、
塩素イオン等の混入も皮膜形成を阻害するだけでなく陽
極材料を侵すので好ましくない。On the other hand, the electrolysis conditions are not particularly limited, and the temperature can be room temperature, but it is preferable to control the temperature at about 40 ° C. in order to keep the electrolysis conditions constant. Regarding the current density, 0.5 to 60 A / dm 2
However, the required total chromium deposition amount depends on the current density and the electrolysis time, so to keep them within the appropriate range, the current density is about 1 to 2 A / dm 2 , and the electrolysis time is 30 to It should be about 100 seconds. As described above, such low current density and short-time electrolysis seems to be very advantageous in terms of power supply equipment cost and running cost as compared with ordinary chromium plating and aluminum anodizing treatment. In addition, the anode (counter electrode) used is preferably an insoluble electrode such as lead, lead oxide (catalyst electrode), or carbon, but iron or stainless steel is also possible, and in this case, ions such as iron and nickel that are eluted are several g. / L is acceptable. When stainless steel is used as the anode, chromium (trivalent) may be eluted, but trivalent chromium ions are produced even in the process of depositing metallic chromium at the cathode and accumulate in the bath. On the other hand, nitrate ions, which become an oxidizing acid as anions, and phosphate ions, which have a small solubility product with trivalent chromium ions, reduce the efficiency of film formation and should be avoided as impurities. Also,
Mixing chlorine ions and the like not only hinders film formation but also corrodes the anode material, which is not preferable.
【００１３】次に、クロム供給源として３価クロムイオ
ンのみを含有する電解液を用いた場合について説明す
る。３価クロムイオンは比較的安定なアコ錯体を形成す
るために６価クロム浴に比べてクロム電析が困難である
が、排水処理等に有利であるため種々のタイプの浴が提
唱されている。基本的には硫酸クロム（Ｃｒ2（ＳＯ4）
3）や塩化クロム（ＣｒＣｌ3）をクロム供給源として、
それらを蓚酸・ギ酸・グリシン・オキシカルボン酸等の
有機錯化剤を用いて錯化した浴を用いればよい。電解電
流密度と電解時間を適当に制御することにより、６価ク
ロム浴と同様の皮膜析出が可能であるが、６価クロム浴
にくらべて析出効率が劣るために、同じ電流密度で行う
場合は長い電解時間を必要とする。また、３価クロム浴
の場合、陽極として鉛や酸化鉛を用いると、それらの触
媒性によって浴中３価クロムが６価クロムに酸化してし
まうので、カーボン電極を用いるべきである。Next, the case where an electrolytic solution containing only trivalent chromium ions is used as a chromium supply source will be described. Since trivalent chromium ions form a relatively stable aco complex, it is more difficult to deposit chromium than hexavalent chromium baths, but various types of baths have been proposed because they are advantageous for wastewater treatment and the like. . Basically chromium sulphate (Cr 2 (SO 4 )
3 ) or chromium chloride (CrCl 3 ) as a chromium source,
A bath obtained by complexing them with an organic complexing agent such as oxalic acid, formic acid, glycine and oxycarboxylic acid may be used. By appropriately controlling the electrolysis current density and the electrolysis time, it is possible to deposit a film similar to the hexavalent chromium bath, but the deposition efficiency is inferior to the hexavalent chromium bath. Requires a long electrolysis time. Further, in the case of a trivalent chromium bath, when lead or lead oxide is used as the anode, the trivalent chromium in the bath is oxidized to hexavalent chromium due to their catalytic properties, so a carbon electrode should be used.
【００１４】本発明による皮膜についてクロム付着量を
指標にさらに詳しく述べる。本発明における陰極電解皮
膜の皮膜量は全クロム付着量で見るのが工業的に有利で
ある。これは金属クロムを含むクロム総量を意味し、蛍
光Ｘ線分析等で簡単に測定可能である。本発明が対象と
する水系無機塗料の前処理皮膜として最適な全クロム付
着量は素材により多少異なるので明確に規定することが
困難であるが、多くのアルミニウム系金属表面では約５
０〜３００ｍｇ／ｍ2が良好な範囲といえる。一般的に
は、皮膜量が少なすぎると前処理皮膜としての機能が低
下し、従来技術でみられるような塗装欠陥や塗装後の性
能劣化が起こり易くなる。一方、皮膜量が多すぎる場
合、例えば１０００ｍｇ／ｍ2を越える場合は塗装後の
密着性が劣化し、かつ処理時間が長くなることにより生
産性が低下するので好ましくない。The coating according to the present invention will be described in more detail with the amount of chromium deposited as an index. It is industrially advantageous to view the coating amount of the cathode electrolytic coating in the present invention as the total chromium deposition amount. This means the total amount of chromium including metallic chromium, which can be easily measured by fluorescent X-ray analysis or the like. The optimum total chromium deposition amount as a pretreatment film for the water-based inorganic coating targeted by the present invention is slightly different depending on the material, and thus it is difficult to clearly define it, but it is about 5 on many aluminum-based metal surfaces.
It can be said that 0 to 300 mg / m 2 is a good range. Generally, if the coating amount is too small, the function as a pretreatment coating is deteriorated, and the coating defects and the performance deterioration after coating as seen in the prior art are likely to occur. On the other hand, when the coating amount is too large, for example, when it exceeds 1000 mg / m 2 , the adhesiveness after coating is deteriorated, and the treatment time becomes long, so that productivity is lowered, which is not preferable.
【００１５】本発明による陰極電解処理の作業性につい
てのべる。一般にクロムめっきに代表されるようにクロ
ムイオンを含有する処理液から金属クロム、又はクロム
化合物を電析する場合には一般に電流効率が非常に悪
い。本発明による陰極電解処理においても通電電気量の
うち皮膜形成に消費される割合は高々２０％程度で必ず
しも良いとはいえない。しかし、前述の塗装前処理皮膜
として必要な全クロム付着量が高くとも３００ｍｇ／ｍ
2であることから、析出効率はほとんど問題にする必要
がないと判断されるのである。電解条件は、前述した通
り通常２Ａ／ｄｍ2程度の低電流密度でよく、この条件
で行っても例えば１５０ｍｇ／ｍ2成膜するのに３０〜
６０秒間の電解で充分である。従って、アルミニウムの
陽極酸化のように３〜５Ａ／ｄｍ2の電流密度で数１０
分間の電解時間を必要とすることに比較すると、作業
性、設備、並びに生産効率的にも極めて有利な方法とい
うことができる。The workability of the cathodic electrolytic treatment according to the present invention will be described. Generally, current efficiency is very poor when metal chromium or a chromium compound is electrodeposited from a treatment liquid containing chromium ions as represented by chromium plating. Even in the cathodic electrolysis treatment according to the present invention, the ratio of the amount of electricity supplied to the film formation is at most about 20%, which is not necessarily good. However, even if the total chromium deposition required for the above-mentioned coating pretreatment film is at most 300 mg / m
Since it is 2, it is judged that the deposition efficiency should hardly be a problem. As described above, the electrolysis condition may be a low current density of usually about 2 A / dm 2 , and even if the electrolysis is carried out under these conditions, for example, 150 mg / m 2 is 30 to 30
Electrolysis for 60 seconds is sufficient. Therefore, like the anodic oxidation of aluminum, the current density of 3 to 5 A / dm 2 can be applied to several tens of tens.
It can be said that this method is extremely advantageous in terms of workability, equipment, and production efficiency, as compared with the case of requiring electrolysis time of a minute.
【００１６】陰極電解処理により形成される皮膜は、既
に述べた反応型、塗布型クロメート処理において該処理
後不可欠であった空焼き処理の必要が無く、陽極酸化処
理後速やかに塗装しなければならないとした工程上の制
約もない。この方法により形成される皮膜は不均一に存
在する金属クロムとそれを覆う３価クロムの水和酸化物
を主体とし、場合によってはさらに微量の６価クロムも
含有する複合型のクロメート皮膜であることが判明して
いる。このうち３価クロムにより構成されるクロメート
皮膜は強アルカリに侵されるため、何故このような強ア
ルカリタイプの水系無機塗料の塗装下地として前記３価
クロム系皮膜が良好なのかは不明である。この理由を考
察すると、理由としては次の二つが考えられる。金属
クロムに比較してクロメートの膜厚が数１０オングスト
ロームときわめて薄いこと、本陰極電解処理により素
材表面の自然電位分布がよりフラットになりアルカリに
よる腐食の発端となる局部電池が形成されにくくなるこ
とによることが推定される。The film formed by the cathodic electrolytic treatment must be applied immediately after the anodic oxidation treatment without the need for the air-baking treatment which was indispensable after the treatment in the above-mentioned reaction type and coating type chromate treatment. There is no restriction on the process. The film formed by this method is a composite type chromate film mainly composed of non-uniformly present metallic chromium and a hydrated oxide of trivalent chromium covering it, and in some cases also containing a trace amount of hexavalent chromium. It turns out. Of these, the chromate film composed of trivalent chromium is attacked by a strong alkali, and it is unclear why the trivalent chromium film is good as a coating base for such a strong alkaline type water-based inorganic paint. Considering this reason, the following two reasons can be considered. Compared to metallic chromium, the film thickness of chromate is extremely thin, about several tens of angstroms, and this cathodic electrolysis process makes the natural potential distribution on the surface of the material flatter, making it difficult to form a local battery that is the origin of corrosion by alkali. It is estimated that
【００１７】本発明による水系無機塗料の塗装前処理法
はアルミニウム系金属表面の塗装の場合にさらに副次的
なメリットを得ることができる。これは全クロム付着量
１５０ｍｇ／ｍ2以下の皮膜形成において得られるもの
であって、前述の如く制限された皮膜量では素材外観を
殆ど変化させずに、あたかも無処理であるかのような、
アルミニウム素地に起因した美しい金属光沢を有する外
観を呈することである。その結果、本発明による塗装前
処理皮膜はクリア塗装下地として最適であるということ
ができる。さらに、水系無機塗料は塗料自体が強アルカ
リ性を呈するため使用できる顔料にはある程度の制約が
あり、通常隠ぺい性の低いものが使用されているのが現
状である。このことは有機樹脂系の塗料に比較し色合い
が独特で、特に建材分野で注目を集める結果となってい
るが、一方では、水系無機塗料の低い隠ぺい性の故に塗
装前処理皮膜の色調の微妙な変化により同じ水系無機塗
料を塗装しても仕上がり外観が異なるといった問題を有
している。しかし、本発明による塗装前処理ではこのよ
うな問題を懸念する必要が殆ど無いといった副次的メリ
ットが得られる。The pretreatment method for coating a water-based inorganic coating material according to the present invention can obtain additional merits when coating an aluminum-based metal surface. This is obtained in the formation of a coating film having a total chromium deposition amount of 150 mg / m 2 or less, and with the limited coating film amount as described above, the appearance of the material is hardly changed, and it is as if no treatment was performed.
It is to have an appearance with a beautiful metallic luster due to the aluminum base. As a result, it can be said that the pretreatment film for coating according to the present invention is optimal as a clear coating base. Furthermore, since the water-based inorganic coating material exhibits strong alkalinity, there are some restrictions on the pigments that can be used, and in the present situation, pigments having a low hiding property are usually used. This has a unique color tone compared to organic resin-based paints, and it has attracted attention especially in the field of building materials.On the other hand, due to the low hiding property of water-based inorganic paints, the color tone of the pre-treatment film is subtle. However, even if the same water-based inorganic paint is applied, the finished appearance will be different. However, the pretreatment for coating according to the present invention has a secondary merit that there is almost no need to worry about such a problem.
【００１８】以上述べた陰極電解法は本発明が対象とす
る水系無機塗料の塗装下地としてばかりではなく、ゾル
ゲル型無機塗料や通常の有機樹脂系の塗料にも適用可能
である。塗膜密着性や耐食性などの塗装後の性能につい
ては、従来技術である塗布型、反応型クロメート処理に
比べてより優れており。素材がアルミニウミの場合は塗
装前処理として最も優れるといわれる陽極酸化処理に優
るとも劣らない。従って、陰極電解処理のための設備は
本発明が対象とする水系無機塗料による塗装ばかりでは
なく、一般の塗装系にも適用可能でありそのための投資
も無駄にならない。The cathodic electrolysis method described above can be applied not only to the coating base of the water-based inorganic coating material, which is the object of the present invention, but also to a sol-gel type inorganic coating material and an ordinary organic resin-based coating material. The post-painting properties such as coating adhesion and corrosion resistance are superior to the conventional coating and reactive chromate treatments. When the material is aluminium, it is as good as anodizing, which is said to be the best pretreatment for painting. Therefore, the facility for cathodic electrolysis can be applied not only to the coating with the water-based inorganic coating which is the subject of the present invention, but also to a general coating system, and the investment therefor is not wasted.
【００１９】[0019]
【実施例】本発明について実施例と比較例を挙げてさら
に具体的に説明する。以下に試験片の材質とそれらの作
製方法について説明する。各々の実施例、比較例におけ
る試験片は下記の（１）〜（６）の工程で作製したが、
比較例６及び１３については塗装の前処理を脱脂のみと
し、従って（３）、（３’）または（３”）、および
（４）の工程を省略した。一方、比較例１〜５、７〜
８、９〜１２については陰極電解処理のかわりに反応型
クロメート処理、もしくは陽極酸化処理を行ったため、
従って（３）のかわりに（３’）もしくは（３”）の工
程を採用した。EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples. The materials of the test pieces and the method for producing them will be described below. The test pieces in each of the examples and comparative examples were manufactured by the following steps (1) to (6),
For Comparative Examples 6 and 13, the pretreatment for coating was only degreasing, and therefore the steps (3), (3 ′) or (3 ″), and (4) were omitted. On the other hand, Comparative Examples 1 to 5, 7 ~
For 8 and 9 to 12, the reaction type chromate treatment or the anodizing treatment was performed instead of the cathodic electrolysis treatment.
Therefore, instead of (3), the process of (3 ') or (3 ") was adopted.
【００２０】１．供試試験材 ・アルミ鋳造合金（ＪＩＳ ＡＣ４Ｃ）フライス研削材 ・アルミ鋳造合金（ＪＩＳ ＡＤＣ１２） ・ＪＩＳ Ａ５０５２板材1. Test material ・ Aluminum cast alloy (JIS AC4C) milling grinding material ・ Aluminum cast alloy (JIS ADC12) ・ JIS A5052 plate material
【００２１】２．試験片作製工程 （１）アルカリ脱脂 ノンエッチングタイプのアルカリ脱脂剤（日本パーカラ
イジング製、ファインクリーナー４３２７）の２％水溶
液を用い、温度６０℃、１分間スプレー脱脂を行った。 （２）洗浄 脱イオン水を用いて２０秒間スプレー洗浄を行った。 （３）陰極電解 第１表に示した所定のクロム含有電解液を用い、第２表
に示した電解条件により陰極電解を行った。ただし、第
１表において、６価クロム含有浴（Ｎｏ．１〜２）の場
合は陽極としてステンレス電極（ＳＵＳ３０４）を３価
クロム浴（Ｎｏ．３）の場合は炭素電極を用いた。ま
た、基本的に工程（６）の塗装は工程（４）（５）終了
直後に行ったが、必要に応じて５日間経時させてから塗
装を行った水準も設けた。 （３’）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７１３の７％水溶液
を用いて、温度５０℃にて２０秒間スプレー処理し、反
応型クロメート皮膜を形成した。以上の処理を行った
後、必要に応じて２３０℃、２０分間の空焼き処理を行
った。 （３”）陽極酸化処理 １５％Ｈ2ＳＯ4水溶液中にて温度３０℃、電流密度３Ａ
／ｄｍ2の条件で陽極電解を行った。このとき、ＡＣ４
Ｃ材では電解時間を２０分間、ＡＤＣ１２材では３０分
間、Ａ５０５２材では１２分間として陽極酸化皮膜厚を
約３μｍに制御した。また、基本的に工程（６）の塗装
は、工程（５）終了直後に行った。また、別に（５）工
程終了後３日間経時させてから塗装を行ったものも準備
した。他に、陽極酸化処理後沸騰脱イオン水中にて２０
分間浸漬し、封孔処理を行ったものも準備した。 （４）洗浄 脱イオン水を用いて２０秒間スプレー洗浄を行った。 （５）乾燥 １００℃に設定したオーブン中にて２分間水切り乾燥を
行った。 （６）塗装 日本パーカライジング製水系無機塗料パルセラコート４
００Ｓ（黒）を用いて目標膜厚２０μｍでスプレー塗装
を行った。塗装後の焼付けは２３０℃にて３０分間保持
することにより行った。2. Test piece preparation step (1) Alkaline degreasing A 2% aqueous solution of a non-etching type alkaline degreasing agent (manufactured by Nippon Parkerizing, Fine Cleaner 4327) was used, and spray degreasing was performed at a temperature of 60 ° C for 1 minute. (2) Cleaning Spray cleaning was performed for 20 seconds using deionized water. (3) Cathodic Electrolysis Cathodic electrolysis was performed using the predetermined chromium-containing electrolytic solution shown in Table 1 under the electrolysis conditions shown in Table 2. However, in Table 1, in the case of the hexavalent chromium-containing bath (Nos. 1 and 2), a stainless steel electrode (SUS304) was used as an anode, and in the case of the trivalent chromium bath (No. 3), a carbon electrode was used. In addition, although the coating of the step (6) was basically performed immediately after the completion of the steps (4) and (5), a level at which the coating was performed after 5 days was provided as necessary. (3 ') Reactive Chromate Treatment A 7% aqueous solution of Alchrome 713 manufactured by Nihon Parkerizing Co., Ltd. was spray-treated at a temperature of 50 ° C for 20 seconds to form a reactive chromate film. After performing the above treatments, an air baking treatment at 230 ° C. for 20 minutes was performed if necessary. (3 ") Anodizing treatment in a 15% H 2 SO 4 aqueous solution at a temperature of 30 ° C. and a current density of 3 A
Anodic electrolysis was performed under the condition of / dm 2 . At this time, AC4
The electrolysis time was 20 minutes for C material, 30 minutes for ADC12 material, and 12 minutes for A5052 material, and the anodic oxide film thickness was controlled to about 3 μm. Further, basically, the coating of the step (6) was performed immediately after the end of the step (5). Separately, a product prepared by coating after allowing 3 days from the completion of step (5) was also prepared. In addition, after anodizing treatment, it is used in boiling deionized water for 20
Also prepared was one that was soaked for a minute and sealed. (4) Cleaning Spray cleaning was performed for 20 seconds using deionized water. (5) Drying Draining was performed for 2 minutes in an oven set to 100 ° C. (6) Painting Water-based inorganic paint made by Nippon Parkerizing Pulcera Coat 4
Spray coating was performed using 00S (black) with a target film thickness of 20 μm. Baking after coating was performed by holding at 230 ° C. for 30 minutes.
【００２２】以下に、試験片の評価方法について説明す
る。 （イ）クロム付着量 蛍光Ｘ線分析装置を用いて試験片表面に存在する全クロ
ム付着量を測定した。 （ロ）塗膜外観観察 塗装、焼付け後の塗膜を観察し、剥がれ、ブツ、フク
レ、割れの発生状況を目視にて観察した。 （ハ）碁盤目密着性試験 塗装面にＮＴカッターで素地に達するように１ｍｍ四方
の碁盤目を１００個描き、セロテープで剥離する。テー
プ剥離後の残存碁盤目数により下記のランクに分けて評
価した。 ○：異常無し △：残存碁盤目数 ９５／１００以上 ×：残存碁盤目数 ９５／１００未満 （ニ）塩水噴霧試験 塗装した試験片にＮＴカッターを用いて素地まで達する
カット傷をつけた後、ＪＩＳ−Ｚ２３７１に基づいて塩
水噴霧を１０００時間行った後に発生したカット傷から
の錆や膨れの最大幅を測定した。 ○：最大錆・膨れ幅１ｍｍ以内 △：最大錆・膨れ幅２ｍｍ以内 ×：最大錆・膨れ幅２ｍｍ超過The test piece evaluation method will be described below. (A) Chromium adhesion amount The total chromium adhesion amount present on the surface of the test piece was measured using a fluorescent X-ray analyzer. (B) Observation of coating film appearance The coating film after coating and baking was observed, and the occurrence of peeling, lumps, blisters, and cracks was visually observed. (C) Cross-cut adhesion test Draw 100 crosses of 1 mm square on the coated surface with an NT cutter to reach the substrate, and peel off with cellophane tape. The following ranks were used for evaluation based on the number of squares remaining after tape peeling. ◯: No abnormality Δ: Remaining cross-cut number 95/100 or more ×: Remaining cross-cut number less than 95/100 (d) Salt spray test After making a cut scratch on the coated test piece to reach the base material using an NT cutter, Based on JIS-Z2371, the maximum width of rust and swelling from cut scratches generated after salt spraying for 1000 hours was measured. ◯: Maximum rust / swelling width within 1 mm △: Maximum rust / swelling width within 2 mm ×: Maximum rust / swelling width exceeding 2 mm
【００２３】各々の実施例、並びに比較例における試験
結果を、ＡＣ４Ｃ材については表３に、ＡＤＣ１２材に
ついては表４に、Ａ５０５２材については表５にそれぞ
れ示した。The test results of each of the examples and the comparative examples are shown in Table 3 for the AC4C material, Table 4 for the ADC12 material, and Table 5 for the A5052 material.
【００２４】本実施例、比較例から次のことが言える。 本発明の陰極電解処理を施したアルミニウム材料、ア
ルミニウム合金材料では、実施例１〜６に示したように
水系無機塗料塗装後の外観観察において剥離やフクレ等
の塗装欠陥が起こらず、塗装後の密着性、耐食性におい
ても極めて優れた結果となっている。しかも、反応クロ
メートや陽極酸化処理のように空焼き処理や処理後塗装
までの扱い方に留意する必要が無く工業的に非常に有利
な方法といえる。 これに対して、比較例１〜２、９〜１０に示すように
反応型クロメート処理においては後処理として高温度、
長時間の処理を必要とする空焼き工程を追加しないと塗
装欠陥が発生し、しかもそれを行っても塗装後の密着
性、耐食性は陰極電解処理を行ったものに比較してやや
劣る結果となった。 また、比較例３〜５、１１〜１２に示す陽極酸化処理
においては処理後に時間経過があると塗装欠陥が発生す
るため注意深い工程管理が必要なのと、それを避けるた
めの表面安定化処理として封孔処理を行ったものはむし
ろ塗装欠陥が顕著になる結果となった。しかも、この問
題に充分留意しても塗装後の耐食性は陰極電解処理法に
比べてやや劣る結果となった。 一方、比較例７〜８に示すように対象素材がＡＤＣ１
２材である場合には上に述べた後処理や工程管理を行っ
ても全く塗装が不可能であった。 さらに、比較例６及び１３には塗装前処理を行わなか
った例を挙げたが、もちろんこれらの場合も全く塗装が
不可能であった。The following can be said from the examples and comparative examples. With the aluminum material and aluminum alloy material subjected to the cathodic electrolysis treatment of the present invention, no coating defects such as peeling and blistering occur in the appearance observation after coating with the water-based inorganic paint as shown in Examples 1 to 6, and The results are also extremely excellent in terms of adhesion and corrosion resistance. Moreover, it is an industrially very advantageous method because there is no need to pay attention to the handling method such as the dry baking treatment and the coating after the treatment like reactive chromate and anodizing treatment. On the other hand, as shown in Comparative Examples 1 to 2 and 9 to 10, in the reactive chromate treatment, high temperature was used as post-treatment,
If a baking process that requires a long treatment is not added, a coating defect will occur, and even if it is done, the adhesion and corrosion resistance after coating will be slightly inferior to those subjected to cathodic electrolytic treatment. It was Further, in the anodizing treatments shown in Comparative Examples 3 to 5 and 11 to 12, a coating defect occurs if there is a lapse of time after the treatment, so that careful process control is required, and as a surface stabilization treatment to avoid it, sealing is performed. The result of the hole treatment was that the coating defects were rather remarkable. Moreover, even if this problem is fully considered, the corrosion resistance after coating is slightly inferior to that of the cathodic electrolytic treatment method. On the other hand, as shown in Comparative Examples 7 to 8, the target material is ADC1.
In the case of two materials, even if the above-mentioned post-treatment and process control were performed, it was impossible to paint at all. Further, Comparative Examples 6 and 13 include examples in which the pretreatment for coating was not performed, but of course, in these cases, coating was impossible at all.
【００２５】[0025]
【発明の効果】 アルミニウム系金属表面を対象として
水系無機塗料を塗装する際に、該塗装前処理として本発
明の陰極電解処理を行うことにより、複雑な工程を必要
とせずに、また工程上特別な制約を受けることなく、し
かも作業性が良好で、塗膜欠陥の無い美麗な塗装が可能
となるばかりでなく、水系無機塗料の塗膜に対して極め
て高い密着性と耐食性を付与することが可能となる。EFFECTS OF THE INVENTION When a water-based inorganic coating material is applied to an aluminum-based metal surface, the cathodic electrolysis treatment of the present invention is performed as a pretreatment for the coating, thereby eliminating the need for complicated steps and a special process step. It is possible not only to provide good workability without any restrictions, and to achieve beautiful coating with no coating defects, but also to impart extremely high adhesion and corrosion resistance to the coating of water-based inorganic coatings. It will be possible.
【００２６】[0026]
【表１】 [Table 1]
【００２７】[0027]
【表２】 [Table 2]
【００２８】[0028]
【表３】 [Table 3]
【００２９】[0029]
【表４】 [Table 4]
【００３０】[0030]
【表５】 [Table 5]
Claims (1)
塗装する場合の該塗装前処理において、該金属表面を予
め６価クロムイオン及び／又は３価クロムイオンを含有
する酸性水溶液中にて陰極電解処理をすることを特徴と
する、アルミニウム系金属表面の水系無機塗料塗装前処
理方法。1. In the pretreatment for coating an aluminum-based metal surface with a water-based inorganic coating material, the metal surface is subjected to cathodic electrolysis in an acidic aqueous solution containing hexavalent chromium ions and / or trivalent chromium ions in advance. A pretreatment method for coating an aluminum-based metal surface with a water-based inorganic paint, which comprises performing a treatment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10512593A JP3212754B2 (en) | 1993-04-07 | 1993-04-07 | Water-based inorganic paint coating pretreatment method for aluminum-based metal surfaces |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10512593A JP3212754B2 (en) | 1993-04-07 | 1993-04-07 | Water-based inorganic paint coating pretreatment method for aluminum-based metal surfaces |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06293995A true JPH06293995A (en) | 1994-10-21 |
| JP3212754B2 JP3212754B2 (en) | 2001-09-25 |
Family
ID=14399072
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10512593A Expired - Fee Related JP3212754B2 (en) | 1993-04-07 | 1993-04-07 | Water-based inorganic paint coating pretreatment method for aluminum-based metal surfaces |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3212754B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103848572A (en) * | 2012-12-05 | 2014-06-11 | 周伟 | Method for preparing and coating reinforcing steel bar anticorrosive glass coating material |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9790613B2 (en) | 2015-03-17 | 2017-10-17 | Goodrich Corporation | Aluminum alloy anodization |
-
1993
- 1993-04-07 JP JP10512593A patent/JP3212754B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103848572A (en) * | 2012-12-05 | 2014-06-11 | 周伟 | Method for preparing and coating reinforcing steel bar anticorrosive glass coating material |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3212754B2 (en) | 2001-09-25 |
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