JPS5861294A - Preventing method for discoloration of steel plate electroplated on one side - Google Patents

Abstract

PURPOSE:To remove the discoloring materials on an iron surface of a steel plate which is applied with zinc type electroplating on one side in an aq. acidic soln. of sulfuric acid and to improve its appearance by electrolyzing said steel plate in an aq. acidic soln. regulated of the respective concns. of Z<++>, free sulfuric acid, Fe<++>, Fe<+++> by making the polarity of said plate as anode. CONSTITUTION:A steel plate is applied with zinc type electroplating consisting essentially of Zn and contg. Ni, Co, etc. on one side in an aq. acidic soln. of sulfuric acid. The plated steel plate is electrolyzed by making its polarity as anode in an aq. acidic soln. of sulfuric acid which is an electrolytic stripping soln. of the conditions expressed by the equations. The temp. of the electrolytic stripping soln. in this case is preferably >=20 deg.C and the electrolytic current density is preferably >=3A/dm<2>. The plated steel plate after the electrolysis is washed with water added with a water soluble discoloration preventing agent whereby discoloration is prevented. The use of triphosphate and nitrate as said discoloration preventing agent is preferable.

Description

【発明の詳細な説明】 るもので、特に非メッキ面の変色金防止する方法に関す
るものである。DETAILED DESCRIPTION OF THE INVENTION This invention relates in particular to a method for preventing discoloration of gold on non-plated surfaces.

近年メッキ面の耐食性をより向上させるために、厚メッ
キが求められる傾向にある。電気メッキでは、メッキ厚
みが厚いほど大きな通電量が必要となる。従って連続メ
ツキラインで厚メッキの鋼板を製造する場合、メツキラ
インの整流機の電気容量から、メッキ厚みが厚いほどラ
インスピードを低下させる必要が生じる。電気メツキ液
には電気的に安定なことから硫酸水溶液が主として用い
られている。このように低速で電気メッキする場合には
メッキしない面（以下非メッキ面又は鉄面という）がメ
ッキ液中で複雑な酸化物を形成し、茶色に変４色した９
黒褐色に変色（以下黒変と称す）する。これらの変色は
片面亜鉛メッキ鋼板の外観を著しく損うのみならず、鉄
面のリン酸塩処理性も損う。従来このような問題点を解
決するために、いろいろの研究がなされてきたが満足い
くものでなかった。In recent years, there has been a trend for thicker plating to further improve the corrosion resistance of plated surfaces. In electroplating, the thicker the plating, the greater the amount of current required. Therefore, when producing thickly plated steel plates on a continuous plating line, it becomes necessary to reduce the line speed as the plating becomes thicker, due to the electric capacity of the rectifier of the plating line. Sulfuric acid aqueous solution is mainly used as the electroplating solution because it is electrically stable. When electroplating is performed at such a low speed, the surface that is not plated (hereinafter referred to as the non-plated surface or iron surface) forms complex oxides in the plating solution, turning brown and producing a four-colored surface.
Discolors to blackish brown (hereinafter referred to as black discoloration). These discolorations not only significantly impair the appearance of the single-sided galvanized steel sheet, but also impair the phosphating properties of the iron surface. In the past, various studies have been conducted to solve these problems, but the results have not been satisfactory.

本発明は、このような鉄面の変色物質を工業的に、かつ
メッキ面の品質劣化をさせないで除去し鉄面の外観を向
上させることを目的とするものである。The object of the present invention is to improve the appearance of iron surfaces by removing such discoloration substances from iron surfaces industrially and without deteriorating the quality of the plated surfaces.

本発明者らは、鉄面変色を防止するためにメッキ液中で
発生する鉄面の変色原因を種々調査したところ黒変は硫
酸塩性で空気飽和下で発生する鉄の酸性酸化物であるこ
とが判った。そこで本発明者らは、■メッキ液の酸性度
の変更、■メッキ後の水洗水中への防錆剤の添加、■メ
ッキ液中へ除酸素剤の添加、■メッキ後の酸等、種々の
鉄面変色防止方法を試みた。その結果メッキ液の酸性度
の変更については、　　ＰＨを高めても変色防止には十
分な効果が期待出来ないこと、また逆にＰＨを極端に低
下させれば変色防止効果はあるが、メッキ後の水洗以降
で鉄面が発錆するために商品価値のある片面電気メツキ
鋼板を得ることができないことが判った。その後電気メ
ツキ後の水洗液中に防錆剤を添加することも試みたが水
洗以前にすでに変色が発生するので変色を防止する効果
はなかった。In order to prevent iron surface discoloration, the present inventors investigated various causes of discoloration of iron surfaces that occur in plating solutions, and found that the black discoloration is caused by acidic oxides of iron that are sulfate-based and occur under air saturated conditions. It turned out that. Therefore, the present inventors proposed various methods such as: (1) changing the acidity of the plating solution, (2) adding a rust preventive agent to the washing water after plating, (2) adding an oxygen scavenger to the plating solution, and (2) adding an acid after plating. We tried a method to prevent steel surface discoloration. As a result, with regard to changing the acidity of the plating solution, it was found that even if the pH was increased, sufficient effect in preventing discoloration could not be expected.On the other hand, if the pH was extremely lowered, it would be effective in preventing discoloration, but it would be difficult to prevent discoloration after plating. It was found that it was not possible to obtain a commercially valuable single-sided electroplated steel sheet because the steel surface rusted after washing with water. Afterwards, an attempt was made to add a rust preventive agent to the washing solution after electroplating, but this was not effective in preventing discoloration since discoloration already occurred before washing.

又メッキ後片面電気メッキ鋼板を酸洗する方法　□では
、゛黒変の除去は可能であるが、メッキ金属も酸洗され
メッキ付着量が減少するため実用性がない、したがって
鉄面のみ酸洗する片面酸洗装置の開発がなくしては、酸
洗による黒変除去は困難である。In addition, the method □ of pickling a single-sided electroplated steel sheet after plating ``Although it is possible to remove black discoloration, it is not practical because the plated metal is also pickled and the amount of plating is reduced, so pickling only the steel surface is Without the development of single-sided pickling equipment, it will be difficult to remove black discoloration by pickling.

本発明は以上の実情に鑑み、鋭意検討し、片面電気メツ
キラインにおいて、簡便、確実に適用出来、しかも処理
効果の大きい技術を見出し、鉄面の黒色を除去し、片面
電気メツキ鋼板の品質向上を計ったものである。In view of the above-mentioned circumstances, the present invention has been devised to find a technology that can be easily and reliably applied to a single-sided electroplating line and has a large processing effect, thereby removing the black color from the steel surface and improving the quality of single-sided electroplated steel sheets. It was measured.

その要旨は硫酸酸性水溶液中で鋼板に片面電気亜鉛系メ
ッキを行った後、該鋼板を （Ｚｌ”　）　ｍｏｔ／Ｌ　／　（Ｈ２ＳＯ４）　１　
ｍｏｌ／Ｌ≧θ／／　ｍｏｌ／Ｌ　＞　（Ｈ２８０４）
　ｆ≧θθ！；　ｍｏｔ／ｌ〔Ｆｅ＋１〕≦θ３ｍｏｌ
ｌＬ （Ｆｅ＋＋＋　）≦θ／ｍｏ１７’１ なる条件の硫酸酸性水溶中極性を陽極として電解処理す
ること、及び該電解処理した後引続き水溶性変色防止剤
を添加した水溶液で該メッキ鋼板を洗浄することによっ
て片面電気メツキ鋼板の変色を防止する方法にある。The gist is that after a steel plate is electroplated on one side in a sulfuric acid aqueous solution, the steel plate is coated with (Zl”) mot/L / (H2SO4) 1
mol/L≧θ// mol/L > (H2804)
f≧θθ! ; mot/l[Fe+1]≦θ3mol
1L (Fe+++)≦θ/mo17'1 Electrolytic treatment in a sulfuric acid acid water solution with polarity as an anode, and after the electrolytic treatment, the plated steel sheet is subsequently washed with an aqueous solution to which a water-soluble discoloration inhibitor is added. A method for preventing discoloration of single-sided electroplated steel sheets.

以下本発明の詳細な説明する。The present invention will be explained in detail below.

本発明に係る対象とする電気メツキ鋼板は亜鉛系メッキ
鋼板である。伺故ならば本発明の目的はメッキ層が硫酸
水溶液中で溶解を防止することにあるから、メッキ層が
硫酸水溶液中で顕著に溶解するメッキ成分系が本発明の
対象となるのである。The target electroplated steel sheet according to the present invention is a zinc-based plated steel sheet. Therefore, since the purpose of the present invention is to prevent the plating layer from dissolving in the sulfuric acid aqueous solution, the present invention targets a plating component system in which the plating layer significantly dissolves in the sulfuric acid aqueous solution.

従ってｚｎメッキまたはｚｎを主成分とし、Ｎｉ、　Ｃ
ｏ。Therefore, ZN plating or ZN as the main component, Ni, C
o.

Ｍｏ、Ａｔ等を含む合金メッキが本発明の対象となり、
Ｃｒメッキ、　　Ｓｎメッキは本発明外となる。The present invention targets alloy plating containing Mo, At, etc.
Cr plating and Sn plating are outside the scope of the present invention.

また本発明に係る電気メッキは硫酸系水溶性メッキ液で
行うことを条件゛とし、更に電気メッキするための電解
液成分は電気的に安定な酸性液であることが必要で、単
なる中性液例えば硫酸ナトリウムでは黒変の除去は困難
である。また鉄イオンと錯イオンを形成するフッ化物の
中性塩例えばフッ化ナトリウムは、黒変の電解剥離が可
能であるが、フッ素ガスが発生するため工業的には利用
困難である。In addition, the electroplating according to the present invention must be performed using a sulfuric acid-based water-soluble plating solution, and the electrolyte component for electroplating must be an electrically stable acidic solution, rather than a simple neutral solution. For example, it is difficult to remove black discoloration with sodium sulfate. Further, neutral salts of fluorides, such as sodium fluoride, which form complex ions with iron ions, can be used to electrolytically remove black discoloration, but are difficult to use industrially because they generate fluorine gas.

一方アルカリ性溶液では長時間電解しても、黒変は除去
できない。そこで酸性溶液であるが、酸のなかでも硫酸
が最も良好で塩酸、硝酸、有機酸は電気分解されるので
使用できないし、リン酸、過塩素酸は有害ガスの発生は
なく、電気分解されることもないが、メッキ面の塗料密
着性が硫酸に比較して劣るので適当でない。これは電気
メツキ時、硫酸水溶液中で形成したメッキ層表面組織が
リン酸、過塩素酸にょシ溶解し、脆い表面組織になるた
めと考えられる。これに対し、硫酸中ではたとえ酸によ
って化学的に溶解されても均一な表面形態を形成してい
る。したがってメッキ液と電解液とが同一であることが
塗膜付着性を維持するためにも不可欠の条件となる。On the other hand, with alkaline solutions, black discoloration cannot be removed even if electrolyzed for a long time. Therefore, among acids, sulfuric acid is the best, and hydrochloric acid, nitric acid, and organic acids cannot be used because they are electrolyzed, and phosphoric acid and perchloric acid do not generate harmful gases and are electrolyzed. Although this is possible, it is not suitable because the paint adhesion to the plated surface is inferior to that of sulfuric acid. This is thought to be because during electroplating, the surface structure of the plating layer formed in the sulfuric acid aqueous solution is dissolved by phosphoric acid and perchloric acid, resulting in a brittle surface structure. On the other hand, in sulfuric acid, even if it is chemically dissolved by the acid, it forms a uniform surface morphology. Therefore, it is an essential condition for maintaining coating film adhesion that the plating solution and electrolyte are the same.

次に鉄面の黒色を除去するための電解剥離液の重要成分
は遊離硫酸〔Ｈ２ＳＯ４〕ｆ及びｚｎ＋Ｆ、Ｆｅ＋＋ニ
ある。（Ｈ２ＳＯ４：ｌｆ　　は電解液を酸性に維持し
、鉄面の黒変を除去するために必要である。ｚｎ＋１　
　はメッキ面の電解剥離液への溶解を抑制するために必
要である。ｐｅ＋＋はメッキ表面で（１）式の反応を起
こし、メッキ表面に付着したＦｅは水素過電圧が低い Ｆｅ”　十Ｚｎメッキ　−＋　Ｚｎ＋＋十Ｆｅ　＝−ｆ
ｉｔため（２）式の反応を促進する。Next, the important components of the electrolytic stripper for removing the black color from iron surfaces are free sulfuric acid [H2SO4]f, zn+F, and Fe++. (H2SO4:lf is necessary to maintain the electrolyte acidic and remove black discoloration from the iron surface.zn+1
is necessary to suppress dissolution of the plated surface in the electrolytic stripper. pe++ causes the reaction of equation (1) on the plating surface, and the Fe attached to the plating surface has a low hydrogen overvoltage.
It promotes the reaction of formula (2).

ｚｎメッキ＋２Ｈ＋　→ｚｎ＋＋＋Ｈ２１・・・・・・
川・・（２）剥離液中の〔Ｈ２ＳＯ４〕ｆ濃度が高い程
、剥離液７中の２ｎ＋＋　　濃度を高めにする必要があ
シ、−次的には（Ｈ２ＳＯ４〕ｌｆ度およびｚｎ＋＋濃
度は（Ｚｎ”）　ｍｏｌ／ｌ　／（Ｈ２ＳＯ４）ｆ　ｍ
ｏｌ／１（＝Ｋ　）で管理する必要がある。zn plating +2H+ →zn+++H21...
(2) The higher the [H2SO4]f concentration in the stripping solution, the higher the 2n++ concentration in the stripping solution 7. Next, the (H2SO4]lf degree and zn++ concentration are ( Zn”) mol/l/(H2SO4)f m
It is necessary to manage it with ol/1 (=K).

このに値はθ／以上であることが必要である。This value must be greater than or equal to θ/.

また〔Ｈ２ＳＯ４〕ｆの濃度はθθ！；ｍｏ！７／を以
上の濃度が必要で、θ０　！；　ｍ　ｏ　ｔ／を未満で
は界面のＰＨが高く電解剥離の効果は少ない。［Ｈ２Ｓ
Ｏ４，Ｉｆ濃度が　／ｍｏｔ／を以上となると廃酸処理
が困難になるため望ましくない。またｚｎ＋＋濃度はに
値で定められ、Ｋ値の上限についてはｚｎ＋＋濃度が上
昇するとｚｎＳＯ４・７Ｈ２０の沈殿が発生し、Ｚｎ＋
＋濃度は一定値以上にはならず、それ迄を限度とする。Also, the concentration of [H2SO4]f is θθ! ;mo! A concentration of 7/ or more is required, and θ0! ; When m o t/ is less than 0, the pH of the interface is high and the effect of electrolytic peeling is small. [H2S
If the O4, If concentration exceeds /mot/, it is undesirable because waste acid treatment becomes difficult. In addition, the zn++ concentration is determined by the value, and regarding the upper limit of the K value, as the zn++ concentration increases, precipitation of znSO4.7H20 occurs, and Zn+
+The concentration will not exceed a certain value, and the limit will be up to that point.

剥離液中のＦ−１濃度はｚｎの溶解速度を低下させるた
め、θ３ｍｏＬ／を以下、好ましくはθ２ｍｏ４／ｌ　
以下であることが必要である。Ｆ８　　　は鉄面および
亜鉛面を溶解する害があるため、剥離液中の混入は有害
である。Ｆｅ＋ｌ＋濃度はθ／ｍａｔ／ｌ　以下好まし
くはθθ、！；ｍｏｔ／ｌ　　以下であることが必要で
ある。Since the F-1 concentration in the stripping solution decreases the dissolution rate of Zn, θ3moL/ is set to less than θ2mo4/L, preferably θ2mo4/L.
It is necessary that the following is true. F8 is harmful because it dissolves iron and zinc surfaces, so its inclusion in the stripping solution is harmful. Fe+l+ concentration is θ/mat/l or less, preferably θθ,! ;mot/l or less is required.

剥離液の温度は２０℃以上が好ましい。２０℃以下では
各種硫酸塩の沈殿が発生し易くなる。また液温か低いほ
ど電気伝導度が低いため、電解電圧が上昇し、電力コス
トが上昇するため、この理由からも２０℃以上が好まし
い。The temperature of the stripping solution is preferably 20°C or higher. At temperatures below 20°C, precipitation of various sulfates tends to occur. In addition, the lower the liquid temperature, the lower the electrical conductivity, which increases the electrolytic voltage and increases the power cost. For this reason as well, the temperature is preferably 20° C. or higher.

また電解液の伝導度向上のためＮａ２８０４　、　（Ｎ
Ｈ４）２８０４等の強電解質塩の添加は好ましい。更に
、黒変の除去が酸性液のみで可能である理由は明らかで
ないが、黒変が除去されるときに生ずる剥離物（鉄化合
物）が中性、またはアルカリ性溶液に難溶性であって、
電解液中に溶出せず、酸性液にのみ溶解することによる
ものと考えられる。In addition, to improve the conductivity of the electrolyte, Na2804, (N
The addition of strong electrolyte salts such as H4) 2804 is preferred. Furthermore, the reason why black discoloration can be removed only with acidic solutions is not clear, but the exfoliated material (iron compound) that is generated when black discoloration is removed is neutral or poorly soluble in alkaline solutions,
This is thought to be due to the fact that it does not dissolve into the electrolytic solution and dissolves only in the acidic solution.

電解電流密度は３　Ａ／ｄｍ”以上が好ましく、これ以
下では電解時間が７５秒以上となシ好ましくない。すな
わち電解時間が長い七連続メツキラインにおいては設備
が大型化し、不経済である。The electrolytic current density is preferably 3 A/dm" or more, and if it is less than this, the electrolytic time is not more than 75 seconds. That is, in a seven-continuous plating line where the electrolytic time is long, the equipment becomes large and uneconomical.

２θθＡ／ａｍ”以上の電流密度は電解時間短縮の設備
的メリットはなく、整流器の大型化および電力ロスなど
の不利をまねくので好ましくない。A current density of 2θθA/am” or more is not preferable because it does not have the equipment advantage of shortening the electrolysis time and causes disadvantages such as an increase in the size of the rectifier and power loss.

次に本発明の第２の特徴として硫酸酸性液による陽極酸
洗によって黒変剥離後引き続いて水溶性の変色防止剤を
添加した　水による木灰をすることである。変色防止剤
は特に鋼板に吸着皮膜を形成せしめ、酸化防止効果を狙
ったもので、リン酸塩、チオリン酸塩、エステル類、ア
ミン、酸アミド、スルフォン酸塩、カルボン酸またはそ
の塩、ホウ酸塩、亜硝酸塩、アルカリ金属塩、水酸化物
、塩基性水酸化物等が好ましい。このなかでも特に発泡
のないもの、排水しやすいこと、衛生上無害であること
等の理由から、第３リン酸塩、ホウ酸塩を用いることが
よシ好ましい。水中における変色防止剤の添加量はθθ
θ／〜／θチの範囲内が好ましく、変色防止効果、経済
性、排水処理等を考慮すればθ／〜２チがよシ望ましい
。Next, the second feature of the present invention is that after the blackening is removed by anodic pickling with a sulfuric acid solution, wood ash is subsequently treated with water to which a water-soluble discoloration inhibitor has been added. Discoloration inhibitors are intended to form an adsorption film on steel plates and have an antioxidant effect, and include phosphates, thiophosphates, esters, amines, acid amides, sulfonates, carboxylic acids or their salts, and boric acids. Salts, nitrites, alkali metal salts, hydroxides, basic hydroxides and the like are preferred. Among these, it is particularly preferable to use tertiary phosphates and borates because they do not cause foaming, are easy to drain, and are hygienically harmless. The amount of anti-discoloration agent added in water is θθ
It is preferably within the range of θ/ to /θchi, and in consideration of discoloration prevention effect, economical efficiency, wastewater treatment, etc., θ/ to 2chi is more desirable.

さて１片面電気メッキ鋼板は酸性電気メッキ浴中金通過
するため、鉄面のリン酸塩処理性（化成処理）が低下す
る。したがって本発明による黒変の電解剥離稜（又は引
きつづいて水洗後）　Ｎｉを鉄面に電解析出させること
は腐食環境に曝された後の塗膜密着性を向上せしめるた
めにも有効である。Now, since gold passes through an acidic electroplating bath in a single-sided electroplated steel sheet, the phosphating property (chemical conversion treatment) of the iron surface is reduced. Therefore, electrolytically depositing Ni on the iron surface of the blackened electrolytically peeled edge (or after subsequent washing with water) according to the present invention is also effective for improving the adhesion of the paint film after being exposed to a corrosive environment. .

必要なＮｉ付着量はコ〜５０■／　ｄｍ’であって、こ
れ以下でも以上でも塗膜の密着性は向上しない。Ｎｉメ
ッキした鋼板が何故良好な燐酸塩処理性を有するかにつ
いては完全に解明された訳ではないが、燐酸塩皮膜形成
反応に際して鉄表面に析出した鉄以外の析出Ｎｉと鉄表
面との間に幼く局部電池作用によシ、表面に析出してい
るＮｉが鉄よシ貴であるから鉄の溶解が促進され、燐酸
塩皮膜形成初期における燐酸塩結晶核の発生が速やかに
行われるためと考えられる。The necessary amount of Ni to be deposited is ~50 cm/dm', and the adhesion of the coating film will not improve if it is less or more than this. Although it is not completely clear why Ni-plated steel sheets have good phosphate treatment properties, there is a possibility that there is a gap between the Ni precipitated on the iron surface during the phosphate film formation reaction and the iron surface. This is thought to be due to the fact that Ni precipitated on the surface is more noble than iron when young due to local battery action, promoting the dissolution of iron and prompting the generation of phosphate crystal nuclei at the early stage of phosphate film formation. It will be done.

従って鉄表面に析出しているＮｉ析出層が不連続である
ことが必要で６り％Ｎｉ析出層が連続となるような析出
量では燐酸塩処理性を向上せしめる効果はない。また、
析出層が不連続であっても、燐酸塩皮膜の結晶核が緻密
に発生するためには局部電池作用の行はれる５ｉｔｅ、
すなわち不°連続部分の密度が適正な範囲にあることが
必要である。析出量の少ない場合は燐酸塩結晶核の発生
密度が低くなるため、燐酸塩処理性の改善が認められな
い。Therefore, it is necessary that the Ni precipitated layer deposited on the iron surface be discontinuous, and if the precipitation amount is such that the 6% Ni precipitated layer is continuous, there is no effect of improving the phosphate treatability. Also,
Even if the deposited layer is discontinuous, in order for the crystal nuclei of the phosphate film to be densely generated, a local battery action is required.
In other words, it is necessary that the density of the discontinuous portions be within an appropriate range. When the amount of precipitation is small, the density of phosphate crystal nuclei generated is low, so no improvement in phosphate treatability is observed.

析出量が多くなるにつれ、燐酸塩結晶核密度は次第に増
加し、極大に達した後は再び減少するが、燐酸塩結晶核
密度が高くなるにつれ、燐酸塩結晶の付着量が減少する
ため、極端に付着量が減少すれば耐食性試験後の塗膜付
着性が悪化する。As the amount of precipitation increases, the phosphate crystal nucleus density gradually increases, reaches a maximum, and then decreases again. However, as the phosphate crystal nucleus density increases, the amount of phosphate crystals attached decreases, so If the amount of adhesion decreases, the adhesion of the coating after the corrosion resistance test will deteriorate.

次に本発明の実施例を述べる。Next, examples of the present invention will be described.

実施例／ 第１図は、従来技術による片面電気メツキ装置の設備配
置図を示し、アンコイラ−／から捲戻されるス）　ＩＪ
ツブは脱脂槽グで脱脂され、水洗槽ｊで水洗され、次に
酸洗槽乙で酸洗、水洗槽７で水洗後、電気メツキ槽にで
片面メ１．キされ、水洗槽ヲで水洗、乾燥機／θで乾燥
されリコイラー７．２で捲取られる。なお図中２、／／
はシャー、３は溶接機である。このようにして、第１図
に示す連続電気亜鉛メッキ装置において、帯鋼（巾７．
２θθｍｍ、板厚θにＷＬｒｒＬ）　　片面／！；Ｏｙ
／ｒｎ”　Ｋ　−ｙ　イア７　ヒ’□ド／ｇ　＄ｍｉｎ
　でメッキしたところ、メッキしない鉄面にメッキ槽出
側で黒褐色の変色が生じた。Embodiment/ FIG. 1 shows the equipment layout of a single-sided electroplating device according to the prior art, in which the IJ is uncoiled from the uncoiler.
The whelk is degreased in a degreasing tank G, washed with water in a washing tank J, then pickled in a pickling tank B, washed with water in a washing tank 7, and then transferred to an electroplating tank for single-sided coating. It is washed with water in a washing tank, dried in a dryer/θ, and rolled up in a recoiler 7.2. In addition, 2 in the figure //
is a shear, and 3 is a welding machine. In this way, in the continuous electrogalvanizing apparatus shown in FIG.
2θθmm, plate thickness θWLrrL) Single side/! ;Oy
/rn” K -y Ia7 H'□do/g $min
When plating with , a blackish brown discoloration occurred on the unplated iron surface at the exit side of the plating tank.

また、この装置の水洗槽ワの水洗液中に変色防止剤（ス
テアリルアミド）をθ３チ添加したが変色を防止するこ
とができなかった。Furthermore, although a discoloration inhibitor (stearylamide) was added to the washing liquid in the washing tank W of this apparatus for θ3 times, discoloration could not be prevented.

なおメッキ液はｚｎＳ０４・７Ｈ２０とＨ２ＳＯ４およ
びＮａＳＯ４を水に溶解したものを使用した。The plating solution used was one in which znS04.7H20, H2SO4, and NaSO4 were dissolved in water.

第２図は本発明による片面電気メツキ装置の設備配置で
ある。第３図も本発明の設備配置であるが、設備内にＮ
ｉメッキ設備を有している。／３は電解剥離槽、／ｌＩ
は水洗槽、／ｊはＮｉメッキ槽、／乙はＮｉメッキ後の
水洗槽である。その他付号は第１図と同じものを表わす
。第７図はＮｉメッキ槽、および電解剥離槽の構造を示
す。／７は電極、／すは押えロール、／？は通電ロール
である。FIG. 2 shows the equipment layout of a single-sided electroplating device according to the present invention. Figure 3 also shows the equipment layout of the present invention, but there is no N in the equipment.
It has i-plating equipment. /3 is electrolytic stripping tank, /lI
is a washing tank, /j is a Ni plating tank, and /O is a washing tank after Ni plating. Other numbers represent the same things as in Figure 1. FIG. 7 shows the structure of the Ni plating tank and the electrolytic stripping tank. /7 is the electrode, /s is the presser roll, /? is an energized roll.

次表はこれらの工程による本発明の実施例および比較例
である。The following table shows examples and comparative examples of the present invention according to these steps.

表中黒変剥離後の鉄面外観の評価基準、Ｎｉメッキの電
着条件および塗膜付着性の評価方法は次の通電である。The criteria for evaluating the appearance of the iron surface after peeling off, the conditions for electrodeposition of Ni plating, and the method for evaluating the adhesion of the coating were the following energization.

黒変剥離後の鉄面外観の評価： ◎　灰色金属色　　○　黄色味のある灰色△　○よりや
＼黒色　×　黒褐色 Ｎｉメッキの電着条件：処理液組成 Ｎ１５Ｑ４・乙Ｈ２０３ｔ／１ （ＮＨ４）　Ｓｏ　４　　　／　３；　ｙ／ＬＰＨグθ 液温　　ダθ℃ 塗膜付着性の評価方法： 鉄面の黒変を電解剥離後、水洗乾燥した片面電機メッキ
鋼板及び鉄面の黒変を電解剥離後水洗、リン酸塩処理し
、／、２θ℃で１０秒間空焼した片面電気メツキ鋼板に
夫々アニオン樹脂を電着塗装した後、鋭利ナイフで鉄素
地に達するクロスカットを施し、ＴｌＳ７．２３７／　
（！；　％　Ｎａｃｔａｑ　）　によって２ｍｈｒ温水
噴霧したものをクロスカット部・にセロテープをはりそ
の剥離幅を表に示した。Evaluation of steel surface appearance after blackening and peeling: ◎ Gray metallic color ○ Yellowish gray △ ○ Slightly black × Electrodeposition conditions for blackish-brown Ni plating: Treatment liquid composition N15Q4・OtsuH203t/1 (NH4) So 4 / 3; y/LPHgθ Liquid temperature daθ℃ Evaluation method for coating film adhesion: After electrolytically peeling off the black discoloration on the steel surface, wash and dry the single-sided electroplated steel plate and wash with water after electrolytically peeling off the black discoloration on the steel surface. A single-sided electroplated steel sheet that had been phosphate-treated and air-baked at 2θ°C for 10 seconds was electrodeposited with an anionic resin, and then a cross cut reaching the iron base was made with a sharp knife to form TlS7.237/
(!; % Nactaq) was sprayed with hot water for 2 mhr, and sellotape was applied to the cross-cut portion, and the peeling width is shown in the table.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は従来技術による片面電気メツキ装置の設備配置
図、第２図及び第３図は本発明実施例装置の設備配置図
、第７図はＮｉメッキ槽および電解剥離槽の構造釜示す
図でちる。 ／・・アンコイラ−コ・・・シャー ３・・・溶接機　　　　　グ・・・脱脂槽Ｓ・・・水洗
槽　　　　　乙・・・酸洗槽７・・・水洗槽　　　　　
に・・・電気メツキ槽２・・・水洗槽　　　　／θ・・
・乾燥機／／・・・シャー　　　　　／、、２・・・リ
コイラー／３・・・電解槽　　　　／ｑ・・・水洗槽／
Ｓ・・・Ｎｉメッキ槽　　／乙・・・水洗槽／７・・・
電　極　　　　７ｇ・・・押えロール／９・・・通電ロ
ールFig. 1 is an equipment layout diagram of a single-sided electroplating device according to the prior art, Figs. 2 and 3 are equipment layout diagrams of an embodiment of the invention equipment, and Fig. 7 is a diagram showing the structure of the Ni plating tank and electrolytic stripping tank. Dechiru. /... Uncoiler Co... Shear 3... Welding machine G... Degreasing tank S... Washing tank B... Pickling tank 7... Washing tank
...Electric plating tank 2...Washing tank /θ...
・Dryer //... Shear /,,2...Recoiler/3...Electrolytic cell /q...Washing tank/
S...Ni plating tank /Otsu...Washing tank/7...
Electrode 7g...presser roll/9...energizing roll

Claims (2)

【特許請求の範囲】[Claims] （１）片面電気メツキ鋼板を製造するに当たシ、硫酸酸
性水溶液中で鋼板に片面電気亜鉛系メッキを行った後、
該鋼板を （Ｚｎ”　３　ｍｏｔ／ｌ　／　（Ｈ２ＳＯ４）ｆｍｏ
！７’ｌ≧θ／／　ｍｏｔ／ｌ＞　（Ｈ２ＳＯ４）ｆ≧
θθ、！；　ｍ　ｏ　ｌ／Ｌ（Ｆｅ”　）≦θ３ｍ６ｔ
／１ （Ｆｅ＋＋＋）≦θ／ｍｏｔ／ｌ なる条件の硫酸酸性水溶液中極性を陽極として電解処理
することを特徴とする片面電気メツキ鋼板の変色防止方
法。 ［Ｈ２ＳＯ４］ｆ　：硫酸酸性水溶液中の遊離硫酸濃度
（ｍｏｔ／ｌ） （ｚｎ＋＋　）　、　ＣＦ、＋＋　〕、　ＣＦ、＋＋＋
　〕：硫酸酸性水溶液中のｚ＋＋　Ｆｅ＋＋、　Ｆ、＋
＋＋＋＋（ｍｏ４／Ｌ）(1) When manufacturing single-sided electroplated steel sheets, after performing single-sided electrolytic zinc plating on the steel plate in a sulfuric acid acidic aqueous solution,
The steel plate is (Zn” 3 mot/l / (H2SO4)fmo
! 7'l≧θ// mot/l> (H2SO4)f≧
θθ,! ; mol/L(Fe”)≦θ3m6t
A method for preventing discoloration of a single-sided electroplated steel sheet, characterized by carrying out electrolytic treatment in a sulfuric acid acidic aqueous solution under the following conditions: /1 (Fe+++)≦θ/mot/l, using the polarity as an anode. [H2SO4]f: Free sulfuric acid concentration in sulfuric acid acidic aqueous solution (mot/l) (zn++), CF,++], CF,+++
]: z++ Fe++, F, + in sulfuric acid acidic aqueous solution
+++++ (mo4/L) （２）片面電気メツキ鋼板を製造するに当たシ、硫酸酸
性水溶液中で鋼板に片面電気亜鉛系メッキを行った後、
該鋼板を （ＺＨ＋＋：Ｉ　ｍｏ４／ｌ／（Ｈ２８０４〕ｆｍｏｌ
／ｌ≧θ／／１゜νｔ＞（Ｈ２ＳＯ４）ｆ≧θθ！；ｍ
ｏｂ／Ｌ（ｒｅ”）≦θ３ｍｏＬ／１ （Ｆｅ”）≦θ／ｍｏ４／Ｌ なる条件の硫酸酸性水溶液中極性を陽極として電解処理
し、引続き水溶性変色防止剤を添加した水溶液で該メッ
キ鋼板を洗浄することを特徴とする片面電気メツキ鋼板
の変色防止方法。 （ＨｚＳＯａ　〕ｆ　：硫酸酸性水溶液中の遊離硫酸濃
度（ｍｏνｔ） 〔ｚｎ＋＋〕、〔Ｆ６＋＋〕、〔Ｆｅ＋０〕：硫酸酸性
水溶液中のＺｎ　　＋　Ｆｅ　　＋　Ｆｅ濃度（ｍｏＬ
／Ｌ）(2) When manufacturing single-sided electroplated steel sheets, after performing single-sided electrolytic zinc plating on the steel sheets in a sulfuric acid acidic aqueous solution,
The steel plate (ZH++: I mo4/l/(H2804) fmol
/l≧θ//1゜νt＞(H2SO4)f≧θθ! ;m
The plated steel sheet was electrolytically treated in an aqueous sulfuric acid solution under the following conditions: ob/L(re")≦θ3moL/1 (Fe")≦θ/mo4/L, with the polarity as the anode, and then the plated steel sheet was treated with an aqueous solution containing a water-soluble discoloration inhibitor. A method for preventing discoloration of a single-sided electroplated steel sheet, which comprises cleaning the same. (HzSOa]f: Free sulfuric acid concentration in sulfuric acid acidic aqueous solution (moνt) [zn++], [F6++], [Fe+0]: Zn + Fe + Fe concentration in sulfuric acid acidic aqueous solution (moL
/L)