JPS61106794A - Production of one-side zinc alloy electroplated steel sheet - Google Patents

Abstract

PURPOSE:To obtain a one-side Zn alloy electroplated steel sheet having an unplated side having superior suitability to a chemical conversion treatment by coating one side of a steel sheet not to be plated with the protective plating of pure Zn, plating the other side with a Zn alloy, and removing the protective plating by an electrolytic pickling. CONSTITUTION:The steel sheet is pretreated, and one side of the steel sheet not to be plated is coated with the protective plating of pure Zn by a conventional method. After the steel sheet is washed, the other side of the steel sheet is electroplated with the Zn alloy by a prescribed method. The steel sheet is then washed and subjected to the electrolytic pickling using the unplated side as the anode to dissolve and remove the protective plating of pure Zn. By this method, a one-side Zn alloy electroplated steel sheet having a clean unplated side having superior suitability to the chemical conversion treatment is obtd.

Description

【発明の詳細な説明】 〈産業上の利用分野〉 本発明は、片面電気亜鉛合金めっき鋼板の製造方法に関
するものである。DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing a single-sided electrolytic zinc alloy plated steel sheet.

〈従来の技術とその問題点〉 近年、道路に散布される凍結防止剤による自動車車体の
腐食を防止するために、亜鉛系電気めっき鋼板の使用が
増加している。この場合１両面ともめっきした鋼板では
、溶接性や塗装後の外観に問題があるので、片面のみを
めっきした鋼板を用いることが多い０片面めっき鋼板の
非めっき面は、化成処理性や塗装性において、冷延鋼板
と同等に優れていることが要求される。しかし、亜鉛系
電気めっき鋼板の製造においては、めっき浴として硫酸
浴や塩化物浴の醜性浴を用いることから、非めっき面の
酸食がさけられない、このため、非めっき面は酩不溶解
物（スマット）の蓄積や不純物の析出にともなって汚れ
、筋状のむらを発生したり、化成処理性の劣化をきたす
ことがしばしば起こる。さらにめっき電流の廻り込みに
よる非めっき面へのめっき析出も、化成処理性劣化の一
因であることが多い。<Prior art and its problems> In recent years, the use of zinc-based electroplated steel sheets has increased in order to prevent corrosion of automobile bodies caused by antifreeze agents sprayed on roads. In this case, a steel plate plated on both sides has problems with weldability and appearance after painting, so a steel plate plated on only one side is often used. It is required that it be as good as cold-rolled steel sheets. However, in the production of zinc-based electroplated steel sheets, acid corrosion of the non-plated surface is unavoidable because a sulfuric acid bath or a chloride bath is used as the plating bath. Accumulation of melted matter (smut) and precipitation of impurities often cause staining, streak-like unevenness, and deterioration of chemical conversion treatment properties. Furthermore, plating precipitation on non-plated surfaces due to the plating current passing around is also often a cause of deterioration in chemical conversion treatment properties.

化成処理性劣化とは、均一なりん酢塩結晶が形成せずに
、一部にスケと称される結晶のない部分を生じたり、不
均一な粗大結晶を生じたりするもので、塗装後の耐食性
や密着性の劣化、あるいは外観上の不均一をもたらすこ
とから品質上重要な問題となるものである。Deterioration of chemical conversion treatment property refers to the fact that uniform phosphoric acid salt crystals are not formed, and some areas with no crystals called stagnation are formed, or uneven coarse crystals are formed. This is an important problem in terms of quality because it causes deterioration in corrosion resistance and adhesion, as well as non-uniform appearance.

そこで、この対策として１例えば特開昭５６−２９６６
１に示されるように、めっき初期に、ストリップのめっ
き不要な反対面にも、めっき浴中の通板を完了したとき
に溶解、消失する量のフラッシュめっきをして、非めっ
き面を保護する方法がある。この方法は、たしかにスマ
ット汚れの防１ににとっては有効であるが、浴中通板の
間に、めっき浴中の不純物や、合金めっきの場合はＺｎ
より責な金属が非めっき面に析出し、このため、化成処
理性の劣化をきたすことがしばしばあった。Therefore, as a countermeasure against this problem, for example, JP-A-56-2966
As shown in 1, at the initial stage of plating, flash plating is applied to the opposite side of the strip that does not require plating in an amount that will dissolve and disappear when the strip is passed through the plating bath to protect the non-plated surface. There is a way. This method is certainly effective in preventing smut stains, but during bath-threading, impurities in the plating bath and Zn in the case of alloy plating are removed.
More harmful metals were deposited on the non-plated surface, which often resulted in deterioration of chemical conversion treatment properties.

また、特開昭５８−２２１２９０、特開昭５９−９６２
９２、特開昭５９−１２６７８６等では、非めっき面に
保護めっきをしておき、めっき後、これを電解酸洗で除
去する方法が示されている。これらの中で実施例として
示されている保護めっきはいずれも、めっき面側と同一
の浴を用いた。同一成分の保護めっきである。Also, JP-A-58-221290, JP-A-59-962
No. 92, JP-A No. 59-126786, etc., disclose a method in which protective plating is applied to the non-plated surface and, after plating, this is removed by electrolytic pickling. In all of the protective plating shown as examples among these, the same bath as that on the plating surface side was used. Protective plating with the same ingredients.

この場合、めっきが純ＺｎあるいはＦｅより電位的に卑
な金属とＺｎの合金めっきの場合は、確かに非めっき面
の洗浄化にとって有効な方法であるが。In this case, if the plating is pure Zn or an alloy plating of Zn and a metal that is less potent in potential than Fe, it is certainly an effective method for cleaning the non-plated surface.

Ｚｎ−ＮｉやＺｎ−Ｎ１−Ｇｏなど、Ｆｅより責な金属
を合金組成とする合金めっきにおいては、非めっき面の
合金めっきである保護めっき層を除去する電解酸洗のと
きに、　Ｆｅとそれより責な金属（Ｘｉ、　Ｃｏ等）と
の間の電池作用が活発化し、Ｆｅ面が異常なオーバーエ
ツチング状態を生じるという問題点がある。このような
異常溶解を生じると９元素のｃ化層の消失とあいまって
鋼板表面の性質が大きく変化してしまい、化成処理性の
大幅な劣化をきたす。In alloy plating whose alloy composition is a metal more sensitive than Fe, such as Zn-Ni or Zn-N1-Go, during electrolytic pickling to remove the protective plating layer that is alloy plating on the non-plated surface, Fe and There is a problem in that the battery action with more aggressive metals (Xi, Co, etc.) becomes active, resulting in abnormal overetching of the Fe surface. When such abnormal dissolution occurs, together with the disappearance of the 9-element carbon layer, the properties of the steel sheet surface change significantly, resulting in a significant deterioration of chemical conversion treatability.

〈発明の目的〉 本発明の目的は１以上のような現状に鑑み、Ｆｅより責
な金属を合金組成とするＺｎ系合金電気めっきを処理す
る場合においても、清すでかつ化成処理性のすぐれた非
めっき面を有する片面電気亜鉛合金めっき鋼板の製造方
法を提供せんとするものである。<Objective of the Invention> In view of the above-mentioned current circumstances, the object of the present invention is to provide a method that is clean and has excellent chemical conversion properties even when electroplating a Zn-based alloy whose alloy composition is a metal more sensitive than Fe. It is an object of the present invention to provide a method for manufacturing a single-sided electrolytic zinc alloy coated steel sheet having a non-plated surface.

〈発明の構成〉 本発明によれば、片面電気亜鉛合金めっき鋼板のｔＡ造
に際し５合金めっきを行う以前に、非めっき面に純Ｚｎ
の保護めっきを行い、めっき後、非めっき面を陽極とし
て電解酸洗して、この保護めっき層を除去することによ
り、上記目的を達成することができる。<Structure of the Invention> According to the present invention, pure Zn is applied to the non-plated surface before performing 5 alloy plating during tA construction of a single-sided electrolytic zinc alloy plated steel sheet.
The above object can be achieved by carrying out protective plating, and after plating, electrolytically pickling is performed using the non-plated surface as an anode to remove this protective plating layer.

〈発明の具体的構成〉 以下に本発明の方法を詳細に説明する。<Specific structure of the invention> The method of the present invention will be explained in detail below.

片面電気亜鉛合金めっき鋼板の製造において、合金めっ
きを行う以前に非めっさ面に純Ｚｎの保護めっきを行う
目的は、これにより、浴中通板の間に非めっきのＦｅ面
が耐食されるのを防止するためである。この純Ｚｎめっ
き層は、めっき浴中の通板の間に酸性めっき浴とＦｅの
直接の接触を防止するか、あるいは接触が生じた場合で
も、Ｚｎの優先的な溶解によってＦｅの耐食を防止する
ものである。In the production of single-sided electrolytic zinc alloy coated steel sheets, the purpose of protective plating of pure Zn on the non-plated surface before alloy plating is to protect the non-plated Fe surface from corrosion during bath running. This is to prevent This pure Zn plating layer prevents direct contact between the acidic plating bath and Fe during passing through the plating bath, or even if contact occurs, preferential dissolution of Zn prevents corrosion resistance of Fe. It is.

このため、通常の片面めっきのときに生ずるような非め
っき面の酸不溶解物（スマット）等による汚れが防止で
きる。Therefore, it is possible to prevent staining of the non-plated surface due to acid-insoluble matter (smut), which occurs during normal single-sided plating.

また、保護めっきが、純Ｚｎである理由は、先に述べた
ごとく、非めっき面の電解酸洗時のＦｅ面の異常溶解を
防ぐためであり、かつ、電解酸洗においてＺｎは容易に
溶解、除去されるからである０合金めっきが終ったのち
、ストリップは水洗した後、非めっき面を陽極として保
護めっき層を除去するために電解酸洗される。In addition, the reason why the protective plating is pure Zn is to prevent abnormal dissolution of the Fe surface during electrolytic pickling of the non-plated surface, and Zn is easily dissolved during electrolytic pickling, as mentioned earlier. After the alloy plating is completed, the strip is washed with water and then electrolytically pickled to remove the protective plating layer using the non-plated surface as the anode.

以上の一連の工程を模式的に第１図に示す、電解酸洗の
終ったあとは水洗し、乾燥してコイルに巻き取られるが
、電解酸洗後、さらに化成処理性を改善するために、非
めっき面の研削あるいは旧フラッシュめっき等も可能で
ある。The series of steps described above is schematically shown in Figure 1. After electrolytic pickling, it is washed with water, dried, and wound into a coil. , grinding of non-plated surfaces, old flash plating, etc. are also possible.

以下、本発明についてさらに詳しく説明する。The present invention will be explained in more detail below.

本発明において用いられるアンコイラ−１からの鋼材２
は、その種類は限定されず、常法に従って脱脂、水洗、
酸洗などの前処理（それぞれ３゜４．５）を行う、これ
らの前処理に続いて、６において、非めっき面への純亜
鉛の保護めっきがなされる。めっき浴としては、通常、
ストリー７プにＺｎめっきを行う場合によく用いられる
硫酸浴、塩化物浴あるいはそれらの混合浴等を用いれば
よい。Steel material 2 from uncoiler 1 used in the present invention
The type is not limited, and it is degreased, washed with water,
Following these pre-treatments, such as pickling (3° 4.5 in each case), a protective plating of pure zinc is applied to the unplated surfaces at 6. As a plating bath, usually
A sulfuric acid bath, a chloride bath, or a mixed bath thereof, which are often used when performing Zn plating on stripes, may be used.

非めっき面に純Ｚｎめっきが処理されたあと、ストリッ
プはいったん水洗され、その後、７においてＺｎ合金め
っきがもういっぽうの面に処理される０本発明において
Ｚｎ合金めっきとは、Ｚｎ−Ｎｉ、Ｚｎ−Ｎｉ−Ｃｏ、
　Ｚｎ−Ｎｉ−Ｔｉ、　Ｚｎ−Ｃｒ、　Ｚｎ−Ｎｉ−Ｃ
ｒ、Ｚｎ−Ｎｉ−Ｆｅ、　Ｚｎ−Ｘｌ−Ｆｅ−Ｃｒ、Ｚ
ｎ−Ｆｅ等ノＺｎ系合金めっきを意味する。めっき浴と
しては通常酸性めっき浴が用いられ、硫酸塩、１！！化
物あるいはそれらの混合浴等を用いればよい、また、浴
中にはＮａ２　ＳＯ４、Ｎａ１ｌ、Ｋ　２　ｓｏ４．　
ＫＣＩ等の電導助剤あるいはｐＨ［衝剤等が添加されて
さしつかえない。After pure Zn plating is applied to the non-plated side, the strip is once washed with water, and then Zn alloy plating is applied to the other side in step 7. In the present invention, Zn alloy plating refers to Zn-Ni, Zn -Ni-Co,
Zn-Ni-Ti, Zn-Cr, Zn-Ni-C
r, Zn-Ni-Fe, Zn-Xl-Fe-Cr, Z
It means Zn-based alloy plating such as n-Fe. An acidic plating bath is usually used as a plating bath, and sulfate, 1! ! The bath may contain Na2SO4, Na11, K2so4.
A conductivity aid such as KCI or a pH buffering agent may be added.

めっき条件としては浴ｐＨ１〜４．浴温４０〜７０℃、
電ｒｔ、′！Ｆ、度２Ｏ−２５ＯＡ／ｄｍ’、液流速５
〜３　Ｑ　Ｑ　ｍ／ｗｉｎ等の条件でめっきされる。The plating conditions are bath pH 1-4. Bath temperature 40-70℃,
Electric rt,'! F, degree 2O-25OA/dm', liquid flow rate 5
Plating is performed under conditions such as ~3 Q Q m/win.

このとき、非めっき面の純Ｚｎめっきは浴中通板の間に
酸性めっき浴によって溶解していくが、　Ｆｅ面の汚れ
を効果的に防止するには、少なくともめっき浴中の通板
が完了するまで、非めっき面に存在している必要がある
。At this time, the pure Zn plating on the non-plated surface is dissolved by the acidic plating bath during passing through the bath, but in order to effectively prevent contamination on the Fe surface, it must be removed at least until the passing through the plating bath is completed. , must be present on the non-plated surface.

純Ｚｎめっき層のめっき浴中における溶解速度は、めっ
き浴の種類、　ｐＨ，浴温、ラインスピード檜　　　　
　　　等によって左右される。したがって必要な純Ｚｎ
めっき量は、めっき操業条件により適宜、決定されるが
、おおむね０．５〜５　ｇ／ｒｎ’の付−Ｅ（ｌであれ
ばよい、めっき浴中の通番を完了したストリップは、４
において水洗したあと、８において非めっき面を陽極と
して純Ｚｎ保護めっき層を溶解・除去するため電解酸洗
される。浴としてはＮａ、　Ｋ　。The dissolution rate of the pure Zn plating layer in the plating bath depends on the type of plating bath, pH, bath temperature, and line speed.
etc. Therefore, the necessary pure Zn
The amount of plating is determined as appropriate depending on the plating operating conditions, but it should be approximately 0.5 to 5 g/rn'.
After washing with water at step 8, electrolytic pickling is performed at step 8 to dissolve and remove the pure Zn protective plating layer using the non-plated surface as an anode. Na, K as a bath.

Ｍｇ、　ＡＩ等の可溶性硫ｍ用、あるいはりん酸塩等の
水溶液、あるいはさらにこれらにほう酸塩、炭酸塩等を
添加した浴が使用される。濃度は５０〜３００ｇ／文、
　ｐＨ１，５〜１３．浴温は常温〜８０℃等の範囲で任
意に選択される。また、電流密度は５−２０ＯＡ／ｄｒ
ｎ’、電解時間は０．５〜５秒程度の範囲において、ラ
インの実状に応じて決定される。Baths for soluble sulfur such as Mg and AI, or aqueous solutions of phosphates, or baths in which borates, carbonates, etc. are added to these are used. Concentration is 50-300g/text,
pH 1,5-13. The bath temperature is arbitrarily selected within the range of room temperature to 80°C. Also, the current density is 5-20OA/dr
n', the electrolysis time is determined in the range of about 0.5 to 5 seconds depending on the actual condition of the line.

このようにして、保護めっき層が除去されたストリップ
２は９において乾燥された後、リコイラー１０により巻
き取られる。The strip 2 from which the protective plating layer has been removed in this manner is dried at 9 and then wound up by a recoiler 10.

く実　施　例〉 以下１本発明を実施例をあげて説明する。Example of implementation The present invention will be explained below with reference to examples.

板厚０．７　ａｓｓ　Ｐ　ＣＣ鋼板を脱脂、酸洗したの
ち、非めっき面側にＺｎＳＯ４・？Ｈ２０４００Ｋ／Ｑ
　。After degreasing and pickling a 0.7 ass P CC steel plate, coat the non-plated side with ZnSO4. H20400K/Q
.

Ｎａ２　ＳＯａ　　１００ｇ／ｌ、ｐＨ２，，５，５５
℃の浴を用い　２〜４ｇ７ｍ１の純Ｚｎ保護めっきを行
った。続いて水洗を行ったのち、水平型めっき槽を使用
して、もういっぽうの面に次の条件で片面Ｚｎ−Ｆｌｉ
合金めっきを施した。Na2SOa 100g/l, pH2,5,55
Pure Zn protective plating of 2 to 4 g and 7 ml was carried out using a bath at ℃. After washing with water, one side of Zn-Fli was coated on the other side using a horizontal plating bath under the following conditions.
Alloy plated.

（１）浴組成 ＮｉＳＯ４・ｓｏ２０　　　２５０　ｇ／立ＺｎＳＯ４
・７Ｈ２０１３０ｇｅｌ Ｎａ２　Ｓ０４　　　　　　　４０　ｇ１文（２）浴ｐ
Ｈ１，８ （３）浴温　　　　　　６０℃ （４）電流密度　　　　５０　Ａ／ｄゴ（５）めっき時
間　　　２３５ｅｃ （６）めっき目付量　　３０　ｇ／ｒｒｆ次いで水洗を
行い、引き続き、第１表に示した条件で非めっき面の電
解酸洗を行い、保護めっき層を除き、その後、水洗、乾
燥した。(1) Bath composition NiSO4・so20 250 g/vertical ZnSO4
・7H20130gel Na2 S04 40 g1 sentence (2) Bath p
H1,8 (3) Bath temperature 60°C (4) Current density 50 A/d (5) Plating time 235 ec (6) Plating area weight 30 g/rrf Next, washing with water was performed, and the conditions shown in Table 1 were continued. The non-plated surface was electrolytically pickled to remove the protective plating layer, and then washed with water and dried.

なお、比較例として、Ｚｎ−Ｎｉ合金めつき時に、めっ
きの岐初の段階で非めっき面側に、Ｚｎ−Ｎｉ合金めっ
きを処理したもの、および純Ｚｎの保護めっきをしただ
けで、めっき後電解酸洗を行わなかったもの、あるいは
保護めっきをしなかったもの等も同時に処理した。As a comparative example, when Zn-Ni alloy plating was performed, Zn-Ni alloy plating was applied to the non-plated side at the initial stage of plating, and the case where pure Zn was only protectively plated and the surface after plating was Items that were not electrolytically pickled or protective plated were also treated at the same time.

この後、非めっき面の汚れやむらの有無を目視で判定す
るとともに、表面清浄度の指標として色差計による白色
度（Ｗ）および化学分析によるＮ１付若量の分析を行っ
た。Thereafter, the presence or absence of dirt or unevenness on the non-plated surface was visually determined, and as an index of surface cleanliness, the whiteness (W) was measured using a color difference meter and the amount of N1 adhesion was analyzed using chemical analysis.

さらに１日本バーカーライジング製のりん斂塩処理液、
ボンデライ１？５３ｏ３ｏを用いて。In addition, 1. Phosphate treatment solution manufactured by Nippon Barker Rising,
Using Bonderai 1?53o3o.

ディー、プ方式により、化成処理を行った。化成皮膜は
目視および走査電顕観察により、均一性、結晶の緻密さ
、スケの有無等によってＪｔ価し、化成付着♀も測定し
た。これらの結果は第１表に示す。Chemical conversion treatment was performed using the deep-dip method. The chemical conversion coating was visually inspected and observed with a scanning electron microscope to determine the Jt value based on uniformity, crystal density, presence of scratches, etc., and the chemical adhesion ♀ was also measured. These results are shown in Table 1.

本発明の実施例はいずれも、ＴＬ酵解後清すな表面が得
られ、化成処理性も良好である。これに対し、めっき面
側のＺｎ−Ｍｉと同一浴で、同一成分の保護めっきをし
た比較例１は、電解酸洗の際に以上溶解（オーバーエツ
チング）を生じ、化成処理性が劣った。また、電解酸洗
を行わなかった比較例２．４、保護めっきを行わなかっ
た比較例３は、いずれも非めっき面の清浄度が悪く、化
成処理性も劣る。In all of the Examples of the present invention, a clear surface was obtained after TL fermentation, and the chemical conversion treatment properties were also good. On the other hand, in Comparative Example 1, in which protective plating was performed with the same components as the Zn-Mi on the plated side in the same bath, more dissolution (overetching) occurred during electrolytic pickling, resulting in poor chemical conversion treatment properties. Furthermore, in Comparative Example 2.4 in which electrolytic pickling was not performed and Comparative Example 3 in which protective plating was not performed, the cleanliness of the non-plated surface was poor and the chemical conversion treatment properties were also poor.

〈発明の効果〉 以上の結果から、本発明の方法が４清浄で化成処理性の
優れた非めっき面を有する片面電気亜鉛合金めっき鋼板
の製造方法として、大きい効果をもつことがあきらかで
ある。<Effects of the Invention> From the above results, it is clear that the method of the present invention has a great effect as a method for producing a single-sided electrolytic zinc alloy plated steel sheet having a non-plated surface that is 4-clean and has excellent chemical conversion treatment properties.

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

第１図は本発明による片面電気Ｚｎ合金めっき鋼板の製
造ラインの模式図である。 符号の説明 １・・・アンコイラ−１２・・・ストリップ、３・・・
脱脂設備、４・・・水洗設備、５・・・酸洗設備、６・
・・非めっき面への純Ｚｎめっき設備、７・・・Ｚｎ合
金めっき設備、８・・・非めっき面の電解酸洗設備、９
・・・乾燥設備、１０・・・リコイラーFIG. 1 is a schematic diagram of a production line for a single-sided electrolytic Zn alloy plated steel sheet according to the present invention. Explanation of symbols 1...Uncoiler-12...Strip, 3...
Degreasing equipment, 4... Water washing equipment, 5... Pickling equipment, 6.
...Pure Zn plating equipment for non-plating surfaces, 7...Zn alloy plating equipment, 8...Electrolytic pickling equipment for non-plating surfaces, 9
...Drying equipment, 10...Recoiler

Claims (1)

【特許請求の範囲】[Claims] 片面電気亜鉛合金めっき鋼板の製造に際し、合金めっき
を行う以前に、非めっき面に純Ｚｎの保護めっきを行い
、めっき後、非めっき面を陽極として電解酸洗して、こ
の保護めっき層を除去することを特徴とする、片面電気
亜鉛合金めっき鋼板の製造方法。When manufacturing single-sided electrolytic zinc alloy plated steel sheets, before alloy plating, pure Zn protective plating is applied to the non-plated surface, and after plating, this protective plating layer is removed by electrolytic pickling using the non-plated surface as the anode. A method for producing a single-sided electrolytic zinc alloy plated steel sheet.