JP2008095134A - Surface treatment method for hot dip galvanizing - Google Patents
Surface treatment method for hot dip galvanizing Download PDFInfo
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- JP2008095134A JP2008095134A JP2006275876A JP2006275876A JP2008095134A JP 2008095134 A JP2008095134 A JP 2008095134A JP 2006275876 A JP2006275876 A JP 2006275876A JP 2006275876 A JP2006275876 A JP 2006275876A JP 2008095134 A JP2008095134 A JP 2008095134A
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- hot dip
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Abstract
Description
本発明は、溶融亜鉛めっき製品の一次防錆及び塗装密着性の向上に効果的な表面処理方法に関する。 The present invention relates to a surface treatment method effective for improving primary rust prevention and paint adhesion of hot dip galvanized products.
鉄や鋼製品においては溶融亜鉛めっき処理が広く普及している。
溶融亜鉛めっきは金属光沢が高いものの、白錆が発生しやすく、例えば特開２００２−３５６７８６号に示すようにクロメート処理を施す場合が多い。
しかし、クロメート処理液には６価クロムが含まれているので環境負荷低減の観点からクロメート処理に代替できる表面処理が必要であった。
また、溶融亜鉛めっき製品に塗装処理する場合にあっては、塗装の密着性を確保すべく、リン酸塩処理等の化成皮膜処理や、表面研削を施しているのが現状であり、生産性向上の観点から塗装前処理の省力化が要求されていた。
Hot dip galvanizing is widely used in iron and steel products.
Although hot dip galvanization has a high metallic luster, white rust is likely to occur, and for example, as shown in JP-A-2002-356786, chromate treatment is often performed.
However, since the chromate treatment liquid contains hexavalent chromium, a surface treatment that can be substituted for the chromate treatment is necessary from the viewpoint of reducing the environmental load.
In addition, when coating hot dip galvanized products, chemical film treatment such as phosphate treatment and surface grinding are currently performed to ensure the adhesion of the coating, and productivity From the viewpoint of improvement, labor saving of the pretreatment for painting has been demanded.
クロメート処理に替わる防錆処理として特開昭５１−７１２３３号公報にはタンニン酸０．０１％以上及び陰性ヒドロゾル０．００１％以上含む混合水溶液で表面処理する技術を開示するが、シリカゾルやカオリンゾル等の陰性ゾルの共存が不可欠であり、また、防錆効果も不充分であった。 Japanese Patent Application Laid-Open No. 51-71233 discloses a technique for surface treatment with a mixed aqueous solution containing 0.01% or more of tannic acid and 0.001% or more of negative hydrosol as a rust prevention treatment instead of chromate treatment, such as silica sol and kaolin sol. Coexistence of the negative sol was indispensable, and the antirust effect was insufficient.
本発明は、溶融亜鉛めっき製品の一次防錆及び塗装密着性の向上に効果的な表面処理方法及びこれにより得られる溶融亜鉛めっき品の提供を目的とする。 An object of the present invention is to provide a surface treatment method effective for improving primary rust prevention and paint adhesion of a hot dip galvanized product, and a hot dip galvanized product obtained thereby.
本発明は、溶融亜鉛めっき処理設備においては、被処理品を溶融亜鉛めっき浴に浸漬して亜鉛層（合金亜鉛層を含む）を形成後は鉄素地との反応を制御すべく冷却水にて冷却していることに着目し、本発明に至った。
即ち、被処理品を溶融亜鉛めっき浴から上昇し引き上げた直後のめっき表面は活性であり、このエネルギーを利用すれば冷却水に有機酸やアミン類を添加するだけで化成皮膜が形成され、且つ既設の生産設備に大きな改造が不要であることが明らかになった。
In the hot dip galvanizing processing facility, the present invention uses a cooling water to control the reaction with the iron substrate after the article to be processed is immersed in a hot dip galvanizing bath to form a zinc layer (including an alloy zinc layer). Focusing on the cooling, the present invention has been achieved.
That is, the plating surface immediately after raising and lifting the article to be treated from the hot dip galvanizing bath is active, and if this energy is used, a chemical conversion film is formed only by adding an organic acid or amines to the cooling water, and It became clear that no major modifications were required to existing production facilities.
請求項１記載の溶融亜鉛めっきの表面処理方法は、被処理品を溶融亜鉛めっき浴に浸漬及び上昇後の冷却工程において、冷却水は、亜鉛表面に亜鉛との難水溶性の塩を形成する、有機酸又はアミン類が含まれていることを特徴とする。
亜鉛めっきの表面に発生する白錆は水酸化亜鉛であることから本発明において冷却水に添加する有機酸又はアミン類は亜鉛の表面に水に難溶性の塩を形成するものであればよいがタンニン酸を用いるのが好ましい。
タンニン酸は接着剤効果も有しているからである。
The surface treatment method for hot dip galvanizing according to claim 1 is characterized in that, in the cooling step after the article to be treated is immersed in the hot dip galvanizing bath and raised, the cooling water forms a slightly water-soluble salt with zinc on the zinc surface. And an organic acid or an amine.
Since the white rust generated on the surface of the galvanizing is zinc hydroxide, the organic acid or amines added to the cooling water in the present invention may be any salt that forms a water-insoluble salt on the surface of zinc. It is preferable to use tannic acid.
This is because tannic acid also has an adhesive effect.
本発明においては溶融亜鉛めっきディッピング後の冷却工程における冷却水にタンニン酸等の有機酸あるいはアミン類を添加するだけで一次防錆（簡易防錆）が向上し、また、そのまま他に下地処理を施こすことなく塗装が可能になる。
特に鉛（Ｐｂ）の替わりにビスマス（Ｂｉ）等を添加した環境対応亜鉛めっきにおいてはＢｉが表面に濃縮されやすく、白錆が発生しやすいがこの種の鉛レス亜鉛めっき鋼板等においても防錆効果が高い。
In the present invention, the primary rust prevention (simple rust prevention) can be improved by simply adding an organic acid such as tannic acid or amines to the cooling water in the cooling step after the hot dip galvanizing dipping. Painting is possible without applying.
In particular, in environmentally-friendly galvanizing with bismuth (Bi) added instead of lead (Pb), Bi tends to concentrate on the surface and easily generate white rust. High effect.
本発明の効果を確認すべく以下のような評価を実施した。
（サンプルの作製）
冷却水にタンニン酸を質量比率で１％、５％溶解させた溶液を作製し、被処理品をめっき浴に浸漬後この溶液でサンプルを冷却した。
比較サンプルとして、クロメート処理有り、無しのものを作製した。
サンプル品仕様を図１にまとめて示す。
溶融亜鉛メッキ浴の条件は、４４０〜５５０℃の範囲がよく本サンプルの場合４５０℃に設定した。
また、浴組成も溶融亜鉛めっきに供されている各種浴成が適用できる。
本サンプルはＰｂレスＣｄレスの環境対応めっき浴を用い、質量％でＺｎ：９７．５％以上、Ａｌ：０．００５％、Ｂｉ：０．３％及びＰｂ：５０ｐｐｍ以下、Ｃｄ：１０ｐｐｍ以下のものを用いた。
（試験方法）
（１）亜鉛めっき後の一次防錆試験
各サンプルに対して、４日間の散水暴露試験を実施した。
散水には雨水を使用した。
（２）亜鉛めっき上の塗装性試験
各サンプルに対して、エポキシ粉体焼付け塗装（焼付け温度：２５０℃、塗膜厚さ：約８０μｍ）を行い、碁盤目試験により塗装密着性を評価した。
（試験結果）
（１）亜鉛めっき後の一次防錆性
４日間の散水暴露試験後の各サンプルの表面状態を図２に示す。
クロメート処理無しサンプル３においては、表面全面に白錆が発生していたが、タンニン溶液サンプル１、２においては、一般の水冷サンプル３より防錆性能は向上していた。
タンニン酸の濃度を５％にしたサンプル１は、表面にタンニンのお茶色が部分的に濃く現れているものの白錆の発生はサンプル２より少ない。
タンニン酸を冷却水に添加すると白錆の発生を抑える効果があるが５％を超えるとタンニンの色が表面に出現することから５％以下がよい。
好ましくは０．５〜３．０％の範囲である。
本発明においてはめっき浴から引き上げためっき表面は高温になっていて、活性が高いので薄い濃度であっても充分に難溶性の皮膜が形成される。
また、浸漬時間も１０秒以上確保できれば充分である。
一般的な生産ラインでは１０〜３０秒の範囲がよい。
また、冷却水は放流方式でも循環方式でもよいが放流水に所定の割合でタンニン酸を添加する方法の方が冷却水の品質を維持しやすい。
（２）亜鉛めっき上の塗装性
碁盤目試験の結果を図３に示す。
サンプル３、４は、塗装がほとんど密着しておらず、タンニン酸が入った冷却水に通したサンプル１、２は、サンプル３、４に比べ格段に塗装密着性が向上しているのが明らかになった。
タンニン酸は渋柿の渋み成分として存在しているものであり人体及び環境にも優しいので環境負荷を低減した溶融亜鉛めっき処理品が得られる。
In order to confirm the effect of the present invention, the following evaluation was performed.
(Sample preparation)
A solution in which tannic acid was dissolved in cooling water at a mass ratio of 1% and 5% was prepared. After the article to be treated was immersed in a plating bath, the sample was cooled with this solution.
As comparative samples, samples with and without chromate treatment were prepared.
Sample product specifications are summarized in FIG.
The condition of the hot dip galvanizing bath was well in the range of 440 to 550 ° C, and in the case of this sample, it was set to 450 ° C.
Various bath compositions used for hot dip galvanizing can also be applied.
This sample uses a Pb-less Cd-less environment-friendly plating bath, and in terms of mass%, Zn: 97.5% or more, Al: 0.005%, Bi: 0.3%, Pb: 50 ppm or less, Cd: 10 ppm or less A thing was used.
(Test method)
(1) Primary rust prevention test after galvanization A four-day water spray exposure test was performed on each sample.
Rainwater was used for watering.
(2) Paintability test on galvanization Epoxy powder baking coating (baking temperature: 250 ° C., coating thickness: about 80 μm) was performed on each sample, and coating adhesion was evaluated by a cross-cut test.
(Test results)
(1) Primary rust prevention after galvanization FIG. 2 shows the surface condition of each sample after a water spray exposure test for 4 days.
In sample 3 without chromate treatment, white rust was generated on the entire surface, but in tannin solution samples 1 and 2, the rust prevention performance was improved as compared with general water-cooled sample 3.
Sample 1 with a tannic acid concentration of 5% has less white rust than sample 2 although the brown color of tannin appears partially on the surface.
Addition of tannic acid to cooling water has the effect of suppressing the occurrence of white rust, but if it exceeds 5%, the color of tannin appears on the surface, so 5% or less is preferable.
Preferably it is 0.5 to 3.0% of range.
In the present invention, the plating surface pulled up from the plating bath is at a high temperature and has high activity, so that a sufficiently poorly soluble film is formed even at a low concentration.
Further, it is sufficient if the immersion time can be secured for 10 seconds or more.
In a general production line, the range of 10 to 30 seconds is preferable.
The cooling water may be a discharge method or a circulation method, but the method of adding tannic acid to the discharge water at a predetermined ratio is easier to maintain the quality of the cooling water.
(2) Paintability on galvanization The results of the cross cut test are shown in FIG.
Samples 3 and 4 have almost no coating, and it is clear that Samples 1 and 2 that have passed through cooling water containing tannic acid have significantly improved coating adhesion compared to Samples 3 and 4. Became.
Tannic acid is present as an astringent component of astringency and is friendly to the human body and the environment, so that a hot dip galvanized product with reduced environmental load can be obtained.
請求項１記載の溶融亜鉛めっきの表面処理方法は、被処理品を溶融亜鉛めっき浴に浸漬及び上昇後の冷却工程において、冷却水は、亜鉛表面に亜鉛との難水溶性の塩を形成する、タンニン酸が含まれていることを特徴とする。
亜鉛めっきの表面に発生する白錆は水酸化亜鉛であることから本発明において冷却水に添加する有機酸又はアミン類は亜鉛の表面に水に難溶性の塩を形成するものであればよいがタンニン酸を用いるのが好ましい。
タンニン酸は接着剤効果も有しているからである。
The surface treatment method for hot dip galvanizing according to claim 1 is characterized in that, in the cooling step after the article to be treated is immersed in the hot dip galvanizing bath and raised, the cooling water forms a slightly water-soluble salt with zinc on the zinc surface. Tannic acid is contained.
Since the white rust generated on the surface of the galvanizing is zinc hydroxide, the organic acid or amines added to the cooling water in the present invention may be any salt that forms a water-insoluble salt on the surface of zinc. It is preferable to use tannic acid.
This is because tannic acid also has an adhesive effect.
本発明にかかる溶融亜鉛めっきの表面処理方法は、被処理品を溶融亜鉛めっき浴に浸漬し、次に上昇直後の表面活性な状態から、水にタンニン酸を０．５〜５．０質量％溶解した冷却水に浸漬し冷却したことを特徴とし、溶融亜鉛めっき浴に浸漬し、次に上昇直後の表面活性な状態から、水にタンニン酸を０．５〜５．０質量％溶解した冷却水に浸漬することにより冷却して得られる溶融亜鉛めっき処理品の生産方法に特徴がある。
亜鉛めっきの表面に発生する白錆は水酸化亜鉛であることから本発明において冷却水に添加する有機酸又はアミン類は亜鉛の表面に水に難溶性の塩を形成するものであればよいがタンニン酸を用いるのが好ましい。
タンニン酸は接着剤効果も有しているからである。
In the surface treatment method for hot dip galvanization according to the present invention, the article to be treated is immersed in a hot dip galvanizing bath, and then , from the surface active state immediately after rising, tannic acid is added to water in an amount of 0.5 to 5.0% by mass. Cooled by immersing in dissolved cooling water, immersing in hot dip galvanizing bath, and then cooling from 0.5 to 5.0 mass% of tannic acid in water from the surface active state immediately after rising It is characterized by a method for producing a hot dip galvanized product obtained by cooling by dipping in water.
Since the white rust generated on the surface of the galvanizing is zinc hydroxide, the organic acid or amines added to the cooling water in the present invention may be any salt that forms a water-insoluble salt on the surface of zinc. It is preferable to use tannic acid.
This is because tannic acid also has an adhesive effect.
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| JP2006275876A JP4072971B1 (en) | 2006-10-07 | 2006-10-07 | Surface treatment method for hot dip galvanizing |
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| JP2006275876A JP4072971B1 (en) | 2006-10-07 | 2006-10-07 | Surface treatment method for hot dip galvanizing |
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| JP4072971B1 JP4072971B1 (en) | 2008-04-09 |
| JP2008095134A true JP2008095134A (en) | 2008-04-24 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010127390A (en) * | 2008-11-27 | 2010-06-10 | Honda Motor Co Ltd | Engine assembling method |
| KR101190489B1 (en) | 2010-06-29 | 2012-10-12 | 현대하이스코 주식회사 | Method for manufacturing high tensile strength steel with excellent plating adhesion |
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2006
- 2006-10-07 JP JP2006275876A patent/JP4072971B1/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010127390A (en) * | 2008-11-27 | 2010-06-10 | Honda Motor Co Ltd | Engine assembling method |
| KR101190489B1 (en) | 2010-06-29 | 2012-10-12 | 현대하이스코 주식회사 | Method for manufacturing high tensile strength steel with excellent plating adhesion |
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| JP4072971B1 (en) | 2008-04-09 |
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