JP2000054186A - Electrogalvanized steel sheet excellent in blackening- resistance and good in whiteness degree and appearance after chemical conversion treatment of plated film and its production - Google Patents
Electrogalvanized steel sheet excellent in blackening- resistance and good in whiteness degree and appearance after chemical conversion treatment of plated film and its productionInfo
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- JP2000054186A JP2000054186A JP23011698A JP23011698A JP2000054186A JP 2000054186 A JP2000054186 A JP 2000054186A JP 23011698 A JP23011698 A JP 23011698A JP 23011698 A JP23011698 A JP 23011698A JP 2000054186 A JP2000054186 A JP 2000054186A
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、クロメート処理
を施した場合の耐黒変性が優れ、且つめっき皮膜の白色
度およびリン酸塩処理等の化成処理後の外観が良好な電
気亜鉛めっき鋼板およびその製造方法に関するものであ
る。TECHNICAL FIELD The present invention relates to an electrogalvanized steel sheet having excellent blackening resistance when subjected to a chromate treatment, and having good whiteness of a plating film and good appearance after a chemical conversion treatment such as a phosphate treatment. The present invention relates to the manufacturing method.
【０００２】[0002]
【従来の技術】一般に、電気亜鉛めっき鋼板を無塗装で
使用する場合には、クロメート処理により電気亜鉛めっ
き層の上層にクロメート皮膜を形成することが行われて
おり、このようなクロメート皮膜を形成することによ
り、電気亜鉛めっき鋼板の耐食性は著しく向上する。し
かしながら、クロメート処理電気亜鉛めっき鋼板には、
高温湿潤環境下での貯蔵中にその表面の一部または全部
が灰黒色または茶褐色に変色する、いわゆる黒変現象が
生ずることがあり、このような黒変現象が生じると商品
価値が著しく低下する。このような電気亜鉛めっき鋼板
の黒変現象の発生原因は必ずしも明らかではないが、電
気亜鉛めっき層表面の腐食によるものと考えられ、特
に、電気亜鉛めっき層中に含有されているＰｂが黒変の
発生を促進すると考えられている。2. Description of the Related Art Generally, when an electrogalvanized steel sheet is used without painting, a chromate film is formed on the electrogalvanized layer by a chromate treatment, and such a chromate film is formed. By doing so, the corrosion resistance of the galvanized steel sheet is significantly improved. However, chromate treated galvanized steel sheet
During storage in a hot and humid environment, a part or all of the surface may turn gray-black or brownish brown, a so-called blackening phenomenon may occur. . Although the cause of the blackening phenomenon of such an electrogalvanized steel sheet is not necessarily clear, it is considered to be due to corrosion of the electrogalvanized layer surface. In particular, Pb contained in the electrogalvanized layer is blackened. It is thought to promote outbreaks.
【０００３】従来、電気亜鉛めっき鋼板の黒変を防止す
る方法として、次のような方法が知られている。 特開昭６０−１５２６８０号：不純物であるＰｂイ
オンの含有量を０．２ｐｐｍ以下とした電気亜鉛めっき
浴で鋼板に電気亜鉛めっきを施すことにより、電気亜鉛
めっき鋼板の耐黒変性を向上させる（以下、先行技術１
という）。 特開昭６０−７７９８８号：不純物であるＰｂイオ
ンの含有量の５〜５００倍であって、Ｚｎイオン量の１
／２５以下で且つ１０ｇ／ｌ以下の量のＮｉイオンを含
有する電気亜鉛めっき浴で鋼板に電気亜鉛めっきを施
し、次いでクロメート処理を施すことにより、電気亜鉛
めっき鋼板の耐黒変性を向上させる（以下、先行技術２
という）。Conventionally, the following method has been known as a method for preventing blackening of an electrogalvanized steel sheet. JP-A-60-152680: Improving the blackening resistance of an electrogalvanized steel sheet by subjecting the steel sheet to electrogalvanization in an electrogalvanizing bath in which the content of Pb ions as impurities is 0.2 ppm or less ( Hereinafter, Prior Art 1
). JP-A-60-77988: 5 to 500 times the content of Pb ions as impurities, and 1
The steel sheet is electrogalvanized in an electrogalvanizing bath containing Ni ions in an amount of not more than / 25 and not more than 10 g / l, and then subjected to chromate treatment to improve the blackening resistance of the electrogalvanized steel sheet ( Hereinafter, Prior Art 2
).
【０００４】 特開平２−８３７４号：１００〜３０
０ｐｐｍのＮｉイオンを含有し、且つ不純物であるＰｂ
イオンの含有量が０．５ｐｐｍ以下、Ｎｉイオン含有量
／Ｐｂイオン含有量が５００超である電気亜鉛めっき浴
で鋼板に電気亜鉛めっきを施し、次いでクロメート処理
を施すことにより、電気亜鉛めっき鋼板の耐黒変性を向
上させる（以下、先行技術３という）。JP-A-2-8374: 100-30
Pb containing 0 ppm Ni ion and being an impurity
The steel sheet is electrogalvanized in an electrogalvanizing bath having an ion content of 0.5 ppm or less and a Ni ion content / Pb ion content of more than 500, and then subjected to a chromate treatment to obtain an electrogalvanized steel sheet. Improves blackening resistance (hereinafter referred to as prior art 3).
【０００５】一方、クロメート処理電気亜鉛めっき鋼板
は、家電製品等のように外部から見える製品の材料とし
て使用されることが多いために、その外観が極めて重要
視され、白い表面色調を有していることが要求される。
クロメート処理が施された電気亜鉛めっき鋼板の外観
は、めっきままの鋼板の外観に大きく影響される。すな
わち、めっきままの鋼板における電気亜鉛めっき層の表
面色調が白く、その表面光沢が優れているものほどクロ
メート処理後の外観が美麗になる。On the other hand, since a chromate-treated electrogalvanized steel sheet is often used as a material of a product that can be seen from the outside, such as a home appliance, its appearance is regarded as extremely important, and it has a white surface tone. Is required.
The appearance of the electrogalvanized steel sheet subjected to the chromate treatment is greatly affected by the appearance of the as-plated steel sheet. That is, the surface color tone of the electrogalvanized layer in the as-plated steel sheet is white, and the better the surface gloss, the more beautiful the appearance after the chromate treatment.
【０００６】一般に、電気亜鉛めっき鋼板を塗装して使
用する場合には、塗膜密着性の向上のためにリン酸塩処
理等の化成処理を施した後に塗装することが広く行われ
ている。塗膜の膜厚は製造コストの低減のために薄くす
ることが多く、このように膜厚が薄い場合には、化成処
理後の表面色調が白いほど、塗装外観が美麗になる。従
来、リン酸塩処理が施された電気亜鉛めっき鋼板の表面
色調を向上させる方法として、次のような方法が知られ
ている。[0006] In general, when an electrogalvanized steel sheet is used by painting, it is widely practiced to apply a chemical conversion treatment such as a phosphate treatment in order to improve coating film adhesion. In many cases, the thickness of the coating film is reduced in order to reduce the manufacturing cost. In such a case, the whiter the surface color after the chemical conversion treatment, the more beautiful the appearance of the coating. Conventionally, the following method is known as a method for improving the surface tone of a galvanized steel sheet subjected to a phosphate treatment.
【０００７】 特開昭６３−４０９９号：純亜鉛めっ
き浴中にＮｉイオンが３００ｐｐｍ以上存在すると、純
亜鉛めっき鋼板のリン酸塩処理後における白色度が５０
以下に低下することから、亜鉛粉末によって亜鉛めっき
浴中のＮｉイオンを除去する（以下、先行技術４とい
う）。 特開平１−１２９９９１号：亜鉛めっき浴中のＮｉ
イオンを１０ｐｐｍ以下に管理することによって、リン
酸塩処理後の電気亜鉛めっき鋼板の表面色調を白色に保
つ（以下、先行技術５という）。JP-A-63-4099: When Ni ions are present in a pure galvanizing bath at 300 ppm or more, the whiteness of a pure galvanized steel sheet after phosphate treatment is 50.
Since it decreases below, Ni ions in the zinc plating bath are removed by zinc powder (hereinafter referred to as prior art 4). Japanese Patent Application Laid-Open No. 1-129991: Ni in zinc plating bath
By controlling the ion to 10 ppm or less, the surface tone of the electrogalvanized steel sheet after the phosphate treatment is kept white (hereinafter referred to as Prior Art 5).
【０００８】さらに、上記、のようにＮｉイオンを
規制する以外に、Ｃｏイオンを用いる以下のような技術
が知られている。 特開平５−２７９８８９号：５０〜５０００ｐｐｍ
のＣｏイオンを含有する電気亜鉛めっき浴で鋼板に電気
亜鉛めっきを施し、鋼板の少なくとも１つの表面上に５
０〜１０００ｐｐｍのＣｏを含有する電気亜鉛めっき層
を形成する（以下、先行技術６という）。Further, in addition to the above-mentioned regulation of Ni ions, the following techniques using Co ions are known. JP-A-5-279889: 50-5000 ppm
The steel sheet is electrogalvanized in an electrogalvanizing bath containing Co ions of at least
An electrogalvanized layer containing 0 to 1000 ppm of Co is formed (hereinafter referred to as prior art 6).
【０００９】[0009]
【発明が解決しようとする課題】しかしながら、上述し
た先行技術１〜６には、次のような問題がある。まず、
先行技術１に関しては、めっき層中のＰｂ含有量はめっ
き浴の組成、ｐＨ値、温度、流動状態及びめっき電流密
度等のめっき条件によって大きく変化するため、めっき
浴中のＰｂイオン濃度を０．２ｐｐｍ以下に抑えても黒
変が発生する場合がある。したがって、先行技術１によ
っては、黒変を完全に防止することはできない。However, the above-mentioned prior arts 1 to 6 have the following problems. First,
Regarding Prior Art 1, the Pb content in the plating layer varies greatly depending on the plating conditions such as the composition, pH value, temperature, flow state and plating current density of the plating bath. Black discoloration may occur even if it is suppressed to 2 ppm or less. Therefore, blackening cannot be completely prevented by the prior art 1.
【００１０】加えて、近年の電気亜鉛めっき製造プロセ
スでは、極間距離の短縮化、高電流密度化、製品の高品
質化等の観点から通電用電極の不溶性化が進んでおり、
この不溶性電極として鉛系不溶性電極が広く用いられる
（実開昭６２−１８００７７号、実開平２−７７５９９
号、特公昭６０−２４１９７号、特公平７−１８０３５
号等）。このような鉛系不溶性電極を使用した場合、め
っき浴中へのＰｂイオンの溶出が不可避的に生じ、この
ためめっき浴中のＰｂイオン濃度を０．２ｐｐｍ以下に
するためには、めっき浴中に多量の炭酸ストロンチウム
を添加しなければならない。しかし、このような炭酸ス
トロンチウムの使用は、その添加装置および置換反応槽
等の設備や除去生成物の分離装置を必要とし、さらに比
較的高価な炭酸ストロンチウムを多量に消費することか
ら、電気亜鉛めっき鋼板の製造コストの増加を招く。In addition, in the recent electrogalvanizing manufacturing process, the current-carrying electrodes are made insoluble from the viewpoints of shortening the distance between the electrodes, increasing the current density, and improving the quality of the product.
As this insoluble electrode, a lead-based insoluble electrode is widely used (Japanese Utility Model Application Laid-Open No. 62-180077, Japanese Utility Model Application Laid-Open No. 2-77599).
No., JP-B-60-24197, JP-B7-18035
No.). When such a lead-based insoluble electrode is used, elution of Pb ions into the plating bath inevitably occurs. Therefore, in order to reduce the Pb ion concentration in the plating bath to 0.2 ppm or less, it is necessary to use A large amount of strontium carbonate must be added to the mixture. However, the use of such strontium carbonate requires equipment such as an addition apparatus and a replacement reaction tank, and an apparatus for separating removed products, and consumes a relatively large amount of relatively expensive strontium carbonate. This leads to an increase in steel sheet manufacturing costs.
【００１１】先行技術２および先行技術３では、めっき
浴中へのＮｉイオンの添加によって、電気亜鉛めっき鋼
板の耐黒変性は向上するものの、めっき層中に含まれる
Ｎｉによってめっき皮膜自体の白色度と化成処理（特
に、リン酸塩処理）後の外観が劣化してしまい、製品の
商品価値が著しく損なわれてしまう。後述するように、
電気亜鉛めっき鋼板の外観の劣化を抑制するためにはめ
っき層中のＮｉ含有量を規制する必要があるが、この点
については先行文献２，３は何も示していない。さら
に、不溶性電極として鉛系電極を使用した場合には浴中
Ｐｂ濃度の変動（特に、電極−ストリップ間での局部的
変動）が大きく、このため浴中Ｐｂ濃度に応じた浴中Ｎ
ｉ濃度の管理は、事実上不可能である。In the prior arts 2 and 3, although the blackening resistance of the electrogalvanized steel sheet is improved by adding Ni ions to the plating bath, the whiteness of the plating film itself is increased by the Ni contained in the plating layer. In addition, the appearance after chemical conversion treatment (particularly, phosphate treatment) deteriorates, and the commercial value of the product is significantly impaired. As described below,
In order to suppress the deterioration of the appearance of the electrogalvanized steel sheet, it is necessary to regulate the Ni content in the galvanized layer. However, prior art documents 2 and 3 do not show anything about this point. Further, when a lead-based electrode is used as the insoluble electrode, the fluctuation of the Pb concentration in the bath (particularly, local fluctuation between the electrode and the strip) is large, and therefore, the Nb concentration in the bath according to the Pb concentration in the bath is large.
Management of the i-concentration is virtually impossible.
【００１２】先行技術４および先行技術５は、リン酸塩
処理後の電気亜鉛めっき鋼板の外観の劣化を防止するこ
とはできるものの、耐黒変性を向上させることはできな
い。また、先行技術６はめっき浴中に高価なＣｏを添加
する必要があるため、製造コストの上昇を招く。したが
って本発明の目的は、上述した従来技術の問題を解決
し、クロメート処理した場合の耐黒変性に優れるととも
に、めっき皮膜自体と化成処理後の外観が良好であり、
しかも安価に製造することができる電気亜鉛めっき鋼板
およびその製造方法を提供することにある。Prior Art 4 and Prior Art 5 can prevent deterioration of the appearance of electrogalvanized steel sheet after phosphate treatment, but cannot improve blackening resistance. Further, in the prior art 6, since expensive Co needs to be added to the plating bath, the production cost is increased. Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, while being excellent in blackening resistance when subjected to chromate treatment, the plating film itself and the appearance after the chemical conversion treatment are good,
Moreover, it is an object of the present invention to provide an electrogalvanized steel sheet that can be manufactured at low cost and a method for manufacturing the same.
【００１３】[0013]
【課題を解決するための手段】本発明者らは上述した課
題を解決するために、まず、電気亜鉛めっきの組成がク
ロメート処理後の黒変に及ぼす影響について調べた。そ
の結果、電気亜鉛めっき鋼板における黒変の発生は電気
亜鉛めっき層中のＮｉ含有量とＰｂ含有量に依存し、電
気亜鉛めっき層中のＮｉ含有量を５０ｐｐｍ以上とし、
且つＰｂ含有量を１０ｐｐｍ以下に規制すれば、いかな
る条件でクロメート処理を実施した場合でも黒変が発生
しないことが判った。Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors first examined the effect of the composition of electrogalvanizing on blackening after chromate treatment. As a result, the occurrence of blackening in the electrogalvanized steel sheet depends on the Ni content and the Pb content in the electrogalvanized layer, and the Ni content in the electrogalvanized layer is set to 50 ppm or more.
Further, it was found that if the Pb content was regulated to 10 ppm or less, no blackening occurred even when the chromate treatment was performed under any conditions.
【００１４】また、電気亜鉛めっき層中のＰｂ含有量を
１０ｐｐｍ以下に規制するためにはめっき浴中のＰｂイ
オン量を低濃度に管理することが有効であると考えられ
るが、このような管理を行っても、めっき浴の組成やめ
っき条件によってＰｂの析出量が変化するため、連続電
気亜鉛めっきラインにおいて電気亜鉛めっき層中のＰｂ
含有量を常時１０ｐｐｍ以下に規制することは困難であ
る。It is considered effective to control the amount of Pb ions in the plating bath to a low concentration in order to regulate the Pb content in the electrogalvanized layer to 10 ppm or less. Is carried out, the amount of Pb deposited varies depending on the composition of the plating bath and the plating conditions.
It is difficult to always control the content to 10 ppm or less.
【００１５】そこで、さらに検討を重ねた結果、めっき
浴中のＮｉイオン濃度、Ｐｂイオン濃度およびＮｉイオ
ン濃度とＰｂイオン濃度との比率を所定の範囲に規制
し、且つ通電用電極として貴金属系不溶用電極を用いて
鋼板を電気亜鉛めっきすることにより、Ｎｉ含有量が５
０ｐｐｍ以上で且つＰｂ含有量が１０ｐｐｍ以下のめっ
き層が得られ、これによりクロメート処理を施した場合
の耐黒変性に優れ、しかもめっき皮膜自体と化成処理後
の外観が優れた電気亜鉛めっき鋼板を製造し得ることが
判った。Therefore, as a result of further study, the Ni ion concentration, the Pb ion concentration, and the ratio of the Ni ion concentration to the Pb ion concentration in the plating bath were regulated within a predetermined range, and the noble metal-based insoluble The steel content is reduced to 5 by electrogalvanizing the steel plate using
A galvanized steel sheet having a plating layer having a Pb content of 0 ppm or more and a Pb content of 10 ppm or less, which is excellent in blackening resistance when subjected to chromate treatment, and which has excellent plating film itself and appearance after chemical conversion treatment, is obtained. It was found that it could be manufactured.
【００１６】また、上記の電気亜鉛めっき後、所定量の
亜鉛を含有するリン酸塩処理液で化成処理を施すことに
より、化成処理後の外観がさらに良好な電気亜鉛めっき
鋼板を製造し得ることも判った。本発明は以上のような
知見に基づきなされたもので、その特徴は以下の通りで
ある。Further, after the above-mentioned electrogalvanizing, a chemical conversion treatment is carried out with a phosphating solution containing a predetermined amount of zinc, whereby an electrogalvanized steel sheet having a better appearance after the chemical conversion treatment can be produced. I also understood. The present invention has been made based on the above findings, and the features are as follows.
【００１７】[1] 鋼板の少なくとも一方の表面に、Ｎｉ
含有量が５０〜７００ｐｐｍ、Ｐｂ含有量が１０ｐｐｍ
以下の電気亜鉛めっき層を形成したことを特徴とする耐
黒変性に優れ且つめっき皮膜の白色度と化成処理後の外
観が良好な電気亜鉛めっき鋼板。 [2] 鋼板の少なくとも一方の表面に、下層側電気亜鉛め
っき層を形成し、その上部にＮｉ含有量が５０〜７００
ｐｐｍ、Ｐｂ含有量が１０ｐｐｍ以下であって、めっき
付着量が０．５ｇ／ｍ2以上の上層側電気亜鉛めっき層
を形成したことを特徴とする耐黒変性に優れ且つめっき
皮膜の白色度と化成処理後の外観が良好な電気亜鉛めっ
き鋼板。[1] At least one surface of the steel sheet
Content is 50-700ppm, Pb content is 10ppm
An electrogalvanized steel sheet having the following electrogalvanized layers formed, having excellent resistance to blackening, and having good whiteness of the plating film and good appearance after chemical conversion treatment. [2] A lower electrogalvanized layer is formed on at least one surface of the steel sheet, and a Ni content of 50 to 700
ppm, the Pb content is 10 ppm or less, and the coating weight is 0.5 g / m 2 or more, and the upper electrogalvanized layer is formed. Electrogalvanized steel sheet with good appearance after chemical conversion treatment.
【００１８】[3] 連続電気亜鉛めっきラインにおいて、
鋼板の少なくとも一方の表面に、硫酸亜鉛を主成分と
し、Ｎｉイオン濃度が５０〜１００ｐｐｍ、不純物たる
Ｐｂイオン濃度が０．２ｐｐｍ未満であって、Ｎｉイオ
ン濃度（ｐｐｍ）＞Ｐｂイオン濃度（ｐｐｍ）×５００
を満足する電気亜鉛めっき浴中で、通電用電極として貴
金属系不溶性電極を用いて電気亜鉛めっきを施すことに
より、Ｎｉ含有量が５０〜７００ｐｐｍ、Ｐｂ含有量が
１０ｐｐｍ以下の電気亜鉛めっき層を形成することを特
徴とする、耐黒変性に優れ且つめっき皮膜の白色度と化
成処理後の外観が良好な電気亜鉛めっき鋼板の製造方
法。[3] In a continuous electrogalvanizing line,
At least one surface of the steel sheet has zinc sulfate as a main component, an Ni ion concentration of 50 to 100 ppm, an impurity Pb ion concentration of less than 0.2 ppm, and a Ni ion concentration (ppm)> Pb ion concentration (ppm) × 500
By performing electrogalvanizing using a noble metal-based insoluble electrode as a current-carrying electrode in an electrogalvanizing bath that satisfies the above conditions, an electrogalvanized layer having a Ni content of 50 to 700 ppm and a Pb content of 10 ppm or less is formed. A method for producing an electrogalvanized steel sheet having excellent resistance to blackening, good whiteness of a plating film and good appearance after chemical conversion treatment.
【００１９】[4] 連続電気亜鉛めっきラインにおいて、
鋼板の少なくとも一方の表面に、電気亜鉛めっきを施し
て下層側電気亜鉛めっき層を形成し、次いで、硫酸亜鉛
を主成分とし、Ｎｉイオン濃度が５０〜１００ｐｐｍ、
不純物たるＰｂイオン濃度が０．２ｐｐｍ未満であっ
て、Ｎｉイオン濃度（ｐｐｍ）＞Ｐｂイオン濃度（ｐｐ
ｍ）×５００を満足する電気亜鉛めっき浴中で、通電用
電極として貴金属系不溶性電極を用いて電気亜鉛めっき
を施すことにより、前記下層側電気亜鉛めっき層の上部
にＮｉ含有量が５０〜７００ｐｐｍ、Ｐｂ含有量が１０
ｐｐｍ以下であって、めっき付着量が０．５ｇ／ｍ2以
上の上層側電気亜鉛めっき層を形成することを特徴とす
る、耐黒変性に優れ且つめっき皮膜の白色度と化成処理
後の外観が良好な電気亜鉛めっき鋼板の製造方法。[4] In the continuous electrogalvanizing line,
At least one surface of the steel sheet is subjected to electrogalvanization to form a lower electrogalvanized layer, and then has zinc sulfate as a main component and a Ni ion concentration of 50 to 100 ppm,
The Pb ion concentration as an impurity is less than 0.2 ppm, and the Ni ion concentration (ppm)> Pb ion concentration (pp
m) In an electrogalvanizing bath satisfying x500, electroplating is performed using a noble metal-based insoluble electrode as a current-carrying electrode, so that the Ni content in the upper portion of the lower electrogalvanizing layer is 50 to 700 ppm. , Pb content is 10
ppm or less, forming an upper electrogalvanized layer having a coating weight of 0.5 g / m 2 or more, excellent in blackening resistance, whiteness of the plating film and appearance after chemical conversion treatment. Method for producing an electrogalvanized steel sheet with good performance.
【００２０】[5] 上記[3]または[4]の製造方法におい
て、電気亜鉛めっき後、液中に亜鉛イオンが３．５ｇ／
ｌ以上含まれるリン酸塩処理液で化成処理することを特
徴とする、耐黒変性に優れ且つめっき皮膜の白色度と化
成処理後の外観が良好な電気亜鉛めっき鋼板の製造方
法。[5] In the method of the above-mentioned [3] or [4], after electrogalvanizing, the solution contains 3.5 g / ion of zinc ions.
1. A method for producing an electrogalvanized steel sheet having excellent blackening resistance, excellent whiteness of a plating film and good appearance after a chemical conversion treatment, wherein the galvanized steel sheet is subjected to a chemical conversion treatment with a phosphating solution containing at least l.
【００２１】[0021]
【発明の実施の形態】本発明の電気亜鉛めっき鋼板は、
鋼板の少なくとも一方の表面に、Ｎｉ含有量が５０〜７
００ｐｐｍ、Ｐｂ含有量が１０ｐｐｍ以下の電気亜鉛め
っき層を有することを特徴とする。電気亜鉛めっき層中
のＮｉ含有量が５０ｐｐｍ未満或いはＰｂ含有量が１０
ｐｐｍ超の場合には、クロメート処理した場合の黒変の
発生を抑えることができない。一方、めっき層中のＮｉ
含有量が７００ｐｐｍを超えると化成処理後の電気亜鉛
めっき鋼板の外観が劣化しやすくなる。めっき層中に適
量のＮｉが存在することによってクロメート処理後の黒
変の発生が抑制される理由は必ずしも明らかではない
が、めっき層中のＮｉがめっき表面における亜鉛の酸化
を抑制するためであると考えられる。BEST MODE FOR CARRYING OUT THE INVENTION The galvanized steel sheet of the present invention
Ni content is 50 to 7 on at least one surface of the steel sheet.
It is characterized by having an electrogalvanized layer containing 00 ppm and a Pb content of 10 ppm or less. Ni content in electrogalvanized layer is less than 50 ppm or Pb content is 10
If it exceeds ppm, it is not possible to suppress the occurrence of blackening when subjected to chromate treatment. On the other hand, Ni in the plating layer
If the content exceeds 700 ppm, the appearance of the galvanized steel sheet after the chemical conversion treatment is liable to deteriorate. The reason why the occurrence of black discoloration after chromate treatment is suppressed by the presence of an appropriate amount of Ni in the plating layer is not necessarily clear, but Ni in the plating layer suppresses oxidation of zinc on the plating surface. it is conceivable that.
【００２２】また、電気亜鉛めっき鋼板のめっき皮膜が
下層側電気亜鉛めっき層と上層側電気亜鉛めっき層の２
層構造からなる場合には、上記と同様の理由により、上
層側電気亜鉛めっき層についてＮｉ含有量を５０〜７０
０ｐｐｍ、Ｐｂ含有量を１０ｐｐｍ以下とする必要があ
る。また、この上層側電気亜鉛めっき層のめっき付着量
は０．５ｇ／ｍ2以上とする必要がある。上層側電気亜
鉛めっき層のめっき付着量が０．５ｇ／ｍ2未満では、
上層側電気亜鉛めっき層によって下層側電気亜鉛めっき
層を十分に被覆することができず、下層側電気亜鉛めっ
き層に起因にする黒変を生じてしまうため、十分な黒変
防止効果が得られない。Further, the electroless galvanized steel sheet has two plating films of a lower electrogalvanizing layer and an upper electrogalvanizing layer.
In the case of a layer structure, the Ni content of the upper electrogalvanized layer is set to 50 to 70 for the same reason as described above.
It is necessary that the content of Pb be 0 ppm and the content of Pb be 10 ppm or less. Further, the coating weight of the upper electrogalvanized layer needs to be 0.5 g / m 2 or more. If the coating weight of the upper electrogalvanized layer is less than 0.5 g / m 2 ,
The lower electrogalvanized layer cannot be sufficiently covered by the upper electrogalvanized layer, and blackening caused by the lower electrogalvanized layer occurs, so that a sufficient blackening preventing effect is obtained. Absent.
【００２３】下層側電気亜鉛めっき層のめっき付着量に
特別な制約はないが、めっき付着量量が５ｇ／ｍ2未満
では耐食性が十分に得られない恐れがあり、一方、４０
ｇ／ｍ2を超えるとプレス成形性が劣化する恐れがある
ため、下層側電気亜鉛めっき層のめっき付着量は５〜４
０ｇ／ｍ2の範囲とすることが好ましい。There is no particular restriction on the coating weight of the lower electrogalvanized layer, but if the coating weight is less than 5 g / m 2 , the corrosion resistance may not be sufficiently obtained.
If it exceeds g / m 2 , the press formability may be deteriorated.
It is preferred to be in the range of 0 g / m 2 .
【００２４】次に、Ｎｉ含有量が５０〜７００ｐｐｍ、
Ｐｂ含有量が１０ｐｐｍ以下の電気亜鉛めっき層を得る
ための製造条件について説明する。図１は０．０５ｐｐ
ｍのＰｂイオンを含有する電気亜鉛めっき浴中にＮｉイ
オンを種々の濃度で添加し、このめっき浴を用いて得ら
れた電気亜鉛めっき層中のＰｂ含有量とめっき浴中のＮ
ｉイオン濃度との関係を示している。図１によれば、め
っき浴中のＮｉイオン濃度が高くなるにしたがって、電
気亜鉛めっき層中のＰｂ含有量は減少している。Next, when the Ni content is 50 to 700 ppm,
Manufacturing conditions for obtaining an electrogalvanized layer having a Pb content of 10 ppm or less will be described. Figure 1 shows 0.05pp
Ni ions at various concentrations were added to an electrogalvanizing bath containing m Pb ions, and the Pb content in the electrogalvanized layer obtained by using this plating bath and the N
The relationship with the i-ion concentration is shown. According to FIG. 1, as the Ni ion concentration in the plating bath increases, the Pb content in the electrogalvanized layer decreases.
【００２５】また、図２は１００ｐｐｍのＮｉイオンを
含有する電気亜鉛めっき浴中にＰｂイオンを種々の濃度
で添加し、このめっき浴を用いて得られた電気亜鉛めっ
き層中のＰｂ含有量とめっき浴中のＰｂイオン濃度との
関係を示したものである。図２によれば、めっき浴中の
Ｐｂイオン濃度が低くなるにしたがって、電気亜鉛めっ
き層中のＰｂ含有量は減少している。FIG. 2 shows that Pb ions were added at various concentrations to an electrogalvanizing bath containing 100 ppm of Ni ions, and the Pb content and the Pb content in the electrogalvanized layer obtained using this bath were measured. It shows the relationship with the Pb ion concentration in the plating bath. According to FIG. 2, the Pb content in the electrogalvanized layer decreases as the Pb ion concentration in the plating bath decreases.
【００２６】これら図１及び図２を含めた実験および検
討の結果、硫酸亜鉛を主成分とし、Ｎｉイオン濃度が５
０〜１００ｐｐｍ、Ｐｂイオン濃度が０．２ｐｐｍ未満
であって、Ｎｉイオン濃度（ｐｐｍ）＞Ｐｂイオン濃度
（ｐｐｍ）×５００を満足する電気亜鉛めっき浴中にお
いて、通電用電極として貴金属系不溶性電極を用いて電
気亜鉛めっきを行うことにより、Ｎｉ含有量が５０ｐｐ
ｍ以上で且つＰｂ含有量が１０ｐｐｍ以下の電気亜鉛め
っき層が得られることが判った。As a result of experiments and studies including these FIGS. 1 and 2, it was found that zinc sulfate was the main component and the Ni ion concentration was 5%.
In an electrogalvanizing bath having a Pb ion concentration of 0 to 100 ppm and a Pb ion concentration of less than 0.2 ppm and satisfying Ni ion concentration (ppm)> Pb ion concentration (ppm) × 500, a noble metal-based insoluble electrode is used as a current-carrying electrode. By performing electrogalvanizing with a Ni content of 50 pp
It was found that an electrogalvanized layer having a Pb content of 10 m or more and a Pb content of 10 ppm or less was obtained.
【００２７】Ｎｉ及びＰｂはＺｎに較べてイオン化傾向
が低く、めっき層中に析出しやすい。連続電気亜鉛めっ
きラインでの製造条件を考慮した場合、電気亜鉛めっき
浴中のＮｉイオン濃度が５０ｐｐｍ未満および１００ｐ
ｐｍ超では、めっき層中のＮｉ含有量を５０〜７００ｐ
ｐｍの範囲とすることができない。また、Ｎｉイオン濃
度が５０ｐｐｍ未満ではめっき層中のＰｂ含有量を十分
に低減させることができない。Ni and Pb have a lower ionization tendency than Zn and tend to precipitate in the plating layer. When considering the production conditions in the continuous electrogalvanizing line, the Ni ion concentration in the electrogalvanizing bath is less than 50 ppm and 100 p.
If it exceeds pm, the Ni content in the plating layer should be 50 to 700 p.
pm range. If the Ni ion concentration is less than 50 ppm, the Pb content in the plating layer cannot be reduced sufficiently.
【００２８】また、めっき層中のＰｂ含有量を１０ｐｐ
ｍ以下にするためには、電気亜鉛めっき浴中のＰｂイオ
ン濃度が０．２ｐｐｍ未満であって、且つＮｉイオン濃
度（ｐｐｍ）＞Ｐｂイオン濃度（ｐｐｍ）×５００を満
足する必要がある。電気亜鉛めっき浴中のＰｂイオン濃
度がＮｉイオン濃度の１／５００以上またはＰｂイオン
濃度が０．２ｐｐｍ以上では、めっき層中のＰｂ含有量
を１０ｐｐｍ以下にすることは困難である。The Pb content in the plating layer is 10 pp.
m or less, the Pb ion concentration in the electrogalvanizing bath must be less than 0.2 ppm and the Ni ion concentration (ppm)> Pb ion concentration (ppm) × 500 must be satisfied. When the Pb ion concentration in the electrogalvanizing bath is 1/500 or more of the Ni ion concentration or the Pb ion concentration is 0.2 ppm or more, it is difficult to reduce the Pb content in the plating layer to 10 ppm or less.
【００２９】また、電気亜鉛めっき浴中のＰｂイオン濃
度を０．２ｐｐｍ未満とするためには、通電用電極とし
てＰｂの溶出のない酸化イリジウム等の貴金属系不溶性
電極の使用が不可欠である。亜鉛製自溶性電極や鉛系不
溶性電極では電極中に含まれるＰｂが浴中に溶出するた
め、めっき浴中のＰｂイオン濃度を０．２ｐｐｍ未満に
することができない。In order to reduce the Pb ion concentration in the electrogalvanizing bath to less than 0.2 ppm, it is indispensable to use a noble metal-based insoluble electrode such as iridium oxide which does not elute Pb as a current-carrying electrode. With a zinc self-soluble electrode or a lead-based insoluble electrode, Pb contained in the electrode elutes into the bath, so that the Pb ion concentration in the plating bath cannot be less than 0.2 ppm.
【００３０】また、電気亜鉛めっき後に化成処理を施す
場合、液中に亜鉛イオンが３．５ｇ／ｌ以上含まれるリ
ン酸塩処理液を使用して化成処理を施すことが好まし
い。このように所定量の亜鉛イオンを含有するリン酸塩
処理液で電気亜鉛めっき鋼板を化成処理することにより
リン酸塩結晶が肥大化し、化成処理後の白色度が向上す
る。これは、リン酸塩結晶の肥大化により鋼板表面での
光の吸収量が減少するためであると考えられる。In the case where a chemical conversion treatment is performed after the electrogalvanizing, it is preferable to use a phosphating treatment solution containing 3.5 g / l or more of zinc ions in the solution. By subjecting the electrogalvanized steel sheet to the chemical conversion treatment with the phosphate treatment solution containing a predetermined amount of zinc ions, phosphate crystals are enlarged, and the whiteness after the chemical conversion treatment is improved. This is considered to be because the amount of light absorption on the surface of the steel sheet decreases due to the enlargement of the phosphate crystals.
【００３１】図３は、リン酸塩処理液中にＺｎイオンを
種々の濃度で添加し、このリン酸塩処理液でめっき層中
に１００ｐｐｍのＮｉを含有する電気亜鉛めっき鋼板を
化成処理し、得られた化成処理皮膜の白色度とリン酸塩
処理液中のＺｎイオン濃度との関係を示したものであ
る。図３によれば、リン酸塩処理液中のＺｎイオン濃度
が高くなるにしたがって、化成処理皮膜の白色度が向上
している。そして、リン酸塩処理液中にＺｎイオンが
３．５ｇ／ｌ以上含まれていれば、表面色調の黒ずみ等
の外観劣化は生じない。FIG. 3 shows that zinc ions are added at various concentrations to a phosphating solution, and an electrogalvanized steel sheet containing 100 ppm of Ni in a plating layer is chemically treated with the phosphating solution. It shows the relationship between the whiteness of the obtained chemical conversion coating and the Zn ion concentration in the phosphating solution. According to FIG. 3, as the Zn ion concentration in the phosphating solution increases, the whiteness of the chemical conversion coating increases. When the phosphating solution contains 3.5 g / l or more of Zn ions, appearance deterioration such as darkening of the surface color does not occur.
【００３２】[0032]
【実施例】［実施例１］冷延鋼板を通常の方法で脱脂お
よび酸洗した後、表１および表２に示す金属イオン濃度
に調整されためっき浴を用い、下記に示す条件でめっき
量が２０ｇ／ｍ2の電気亜鉛めっきを施し、鋼板の表面
上にＮｉを含有する電気亜鉛めっき層を形成した。これ
らの電気亜鉛めっき鋼板を下記の(A)、(B)および(C)に
示す３種類の条件でそれぞれクロメート処理し、電気亜
鉛めっき層の上層にクロメート皮膜を形成した。また、
これとは別に下記の条件でリン酸塩処理を施し、電気亜
鉛めっき層の上層にリン酸塩処理皮膜を形成した。[Example 1] A cold-rolled steel sheet was degreased and pickled by a usual method, and then, using a plating bath adjusted to a metal ion concentration shown in Tables 1 and 2, under the conditions shown below under the following conditions: Was subjected to electrogalvanizing of 20 g / m 2 to form an electrogalvanized layer containing Ni on the surface of the steel sheet. Each of these electrogalvanized steel sheets was chromate-treated under the following three conditions (A), (B) and (C) to form a chromate film on the electrogalvanized layer. Also,
Separately, a phosphate treatment was performed under the following conditions to form a phosphate treatment film on the electrogalvanized layer.
【００３３】(1) 電気亜鉛めっき条件 ・めっき浴組成 硫酸亜鉛：４００ｇ／ｌ 硫酸ソーダ：５０ｇ／ｌ ・浴ｐＨ値：１．５ ・浴温：４０〜６０℃ ・浴流速：１〜５ｍ／ｓ ・電流密度：５０〜２００Ａ／ｄｍ2 (1) Electrogalvanizing conditions • Plating bath composition Zinc sulfate: 400 g / l Sodium sulfate: 50 g / l • Bath pH value: 1.5 • Bath temperature: 40 to 60 ° C • Bath flow rate: 1 to 5 m / l s Current density: 50 to 200 A / dm 2
【００３４】(2) クロメート処理条件 (A) シリカ含有塗布型クロメート処理 クロム付着量：４０〜６０ｍｇ／ｍ2 ＳｉＯ2／Ｃｒ：３〜４ (B) 反応型クロメート処理後、薄膜有機樹脂塗布処理 クロム付着量：２０〜２５ｍｇ／ｍ2 樹脂膜厚：１．５〜２．０μｍ (C) 電解型クロメート処理 クロム付着量：２０〜２５ｍｇ／ｍ2 ニッケル付着量：２５〜４５ｍｇ／ｍ2 シリカ付着量：３０〜５０ｍｇ／ｍ2 (2) Chromate treatment conditions (A) Silica-containing coating type chromate treatment Chromium adhesion amount: 40 to 60 mg / m 2 SiO 2 / Cr: 3 to 4 (B) After reaction type chromate treatment, thin film organic resin coating treatment Chromium coating amount: 20-25 mg / m 2 Resin film thickness: 1.5-2.0 μm (C) Electrolytic chromate treatment Chromium coating amount: 20-25 mg / m 2 Nickel coating amount: 25-45 mg / m 2 Silica adhesion Amount: 30-50 mg / m 2
【００３５】(3) リン酸塩処理条件 ・スプレー式リン酸亜鉛系処理 ・リン酸塩処理皮膜付着量：１．５〜２．５ｇ／ｍ2 上記の供試材のうち、電気亜鉛めっき層上にクロメート
皮膜を形成した供試材については下記(a)の耐黒変性試
験を行ない、また、電気亜鉛めっき層上にリン酸塩処理
皮膜を形成した供試材については、下記(b)のリン酸塩
処理後の外観試験を行なった。それらの結果を、めっき
浴中の金属イオン濃度、めっき層の成分組成とともに表
１および表２に示す。(3) Phosphate treatment conditions-Spray zinc phosphate-based treatment-Phosphate treatment film adhesion amount: 1.5 to 2.5 g / m 2 Of the above test materials, electrogalvanized layer The test material having a chromate film formed thereon was subjected to the following blackening resistance test (a), and the test material having a phosphate treatment film formed on an electrogalvanized layer was subjected to the following (b) Was subjected to an appearance test after phosphate treatment. The results are shown in Tables 1 and 2 together with the metal ion concentration in the plating bath and the component composition of the plating layer.
【００３６】(a) 耐黒変性試験 各供試材をそれぞれ複数枚積み重ね、この積み重ねられ
た供試材に対し、温度５０℃、ＲＨ９５％の湿潤試験を
６０日間施した。この湿潤試験の前後の各供試材につい
て、ＪＩＳ Ｚ ８３７０に規定するＬａｂ表色系の明度
指数Ｌ値を測定するとともに、試験前後でのＬ値の変化
量ΔＬを求め、この変化量ΔＬと目視とにより、下記に
より評価した。 ○：ΔＬ≧−２（黒変なし） ×：ΔＬ＜−２（変色あり）(A) Blacking Resistance Test A plurality of test materials were stacked, and the stacked test materials were subjected to a humidity test at a temperature of 50 ° C. and an RH of 95% for 60 days. For each of the test materials before and after the wet test, the lightness index L value of the Lab color system defined in JIS Z 8370 was measured, and the change amount L of the L value before and after the test was determined. It was visually evaluated as follows. ：: ΔL ≧ -2 (no blackening) ×: ΔL <-2 (with discoloration)
【００３７】(b) リン酸塩処理後の外観試験 多光源分光測色計ＭＳＣ−１Ｓ−２Ｂ（スガ試験機
（株）製）を使用して、Ｌａｂ表色系の明度指数Ｌ値を
測定し、このＬ値に基づき下記により外観性を評価し
た。 ○：Ｌ値≧６０ ×：Ｌ値＜６０ 表１および表２によれば、本発明例Ｎｏ．１〜Ｎｏ．９
はいずれの条件でクロメート処理した場合でも優れた耐
黒変性を示し、また、リン酸塩処理後の外観にも優れて
いる。(B) Appearance test after phosphate treatment The lightness index L value of the Lab color system was measured using a multi-source spectrophotometer MSC-1S-2B (manufactured by Suga Test Instruments Co., Ltd.). The appearance was evaluated as follows based on the L value. ：: L value ≧ 60 ×: L value <60 According to Tables 1 and 2, the present invention sample No. 1 to No. 9
Shows excellent blackening resistance even when subjected to chromate treatment under any conditions, and also has an excellent appearance after phosphate treatment.
【００３８】これに対して比較例Ｎｏ．１〜Ｎｏ．３
は、めっき浴中のＮｉイオン濃度が５０ｐｐｍ未満であ
るためめっき層中のＮｉ含有量が５０ｐｐｍ未満であ
り、このため耐黒変性が劣っている。比較例Ｎｏ．４〜
Ｎｏ．６は、めっき浴中のＮｉイオン濃度が１００ｐｐ
ｍを超えているためめっき層中のＮｉ含有量が７００ｐ
ｐｍを超え、このため耐黒変性は良好であるもののリン
酸塩処理後の外観が劣っている。On the other hand, in Comparative Example No. 1 to No. Three
Has a Ni content in the plating layer of less than 50 ppm because the Ni ion concentration in the plating bath is less than 50 ppm, and therefore, blackening resistance is inferior. Comparative Example No. 4 ~
No. No. 6 shows that the Ni ion concentration in the plating bath is 100 pp
m, the Ni content in the plating layer is 700p
pm, the blackening resistance is good, but the appearance after phosphate treatment is inferior.
【００３９】比較例Ｎｏ．７〜Ｎｏ．１３は、めっき浴
中のＰｂイオン濃度がＮｉイオン濃度の１／５００以上
であるため、さらに、一部の比較例についてはＮｉイオ
ン濃度が５０ｐｐｍ未満或いはＰｂイオン濃度が０．２
ｐｐｍ以上であるため、めっき層中のＰｂ含有量が１０
ｐｐｍを超え（さらに、比較例７、８、１０については
Ｎｉ含有量が５０ｐｐｍ未満）、このため耐黒変性が劣
っている。また、比較例Ｎｏ．１１〜Ｎｏ．１３はＮｉ
イオン濃度が１００ｐｐｍを超えているためめっき層中
のＮｉ含有量が７００ｐｐｍを超え、このためリン酸塩
処理後の外観も劣っている。Comparative Example No. 7-No. Sample No. 13 has a Pb ion concentration of 1/500 or more of the Ni ion concentration in the plating bath, and further has a Ni ion concentration of less than 50 ppm or a Pb ion concentration of 0.2
ppm or more, the Pb content in the plating layer is 10
ppm (the Ni content of Comparative Examples 7, 8, and 10 is less than 50 ppm), and therefore, the blackening resistance is inferior. Also, in Comparative Example No. 11-No. 13 is Ni
Since the ion concentration exceeds 100 ppm, the Ni content in the plating layer exceeds 700 ppm, and therefore, the appearance after the phosphate treatment is inferior.
【００４０】比較例Ｎｏ．１４〜Ｎｏ．１８は、リン酸
塩処理液中に含まれる亜鉛イオンが３．５ｇ／ｌ未満で
あるためリン酸塩処理後の外観が劣っている。また、比
較例１７、比較例１８はＰｂイオン濃度がＮｉイオン濃
度の１／５００以上、或いはＰｂイオン濃度が０．２ｐ
ｐｍ以上であるためめっき層中のＰｂ含有量が１０ｐｐ
ｍを超え、このため耐黒変性にも劣っている。Comparative Example No. 14-No. Sample No. 18 is inferior in appearance after phosphating since zinc ions contained in the phosphating solution are less than 3.5 g / l. In Comparative Examples 17 and 18, the Pb ion concentration was 1/500 or more of the Ni ion concentration, or the Pb ion concentration was 0.2 p.
pm or more, the Pb content in the plating layer is 10 pp
m, which is inferior to blackening resistance.
【００４１】[0041]
【表１】 [Table 1]
【００４２】[0042]
【表２】 [Table 2]
【００４３】［実施例２］冷延鋼板を通常の方法で脱脂
および酸洗した後、下層側の電気亜鉛めっきを施し、次
いで、その上層に実施例１の上記(1)と同じ条件で電気
亜鉛めっきを施し、Ｎｉを含有する上層側電気亜鉛めっ
き層を形成した。なお、比較例Ｎｏ．１９〜Ｎｏ．２１
については、下層側の電気亜鉛めっきは施さず、上層側
に相当する電気亜鉛めっきのみを施した。これらの電気
亜鉛めっき鋼板を実施例１で用いた上記(A)、(B)および
(C)に示す３種類の条件でそれぞれクロメート処理し、
電気亜鉛めっき層の上層にクロメート皮膜を形成した。
また、これとは別に実施例１で用いた上記(3)の条件で
リン酸塩処理を施し、電気亜鉛めっき層の上層にリン酸
塩処理皮膜を形成した。Example 2 A cold-rolled steel sheet was degreased and pickled by a usual method, and then subjected to electrogalvanizing on the lower layer, and then the upper layer was subjected to electric power treatment under the same conditions as in the above (1) of Example 1. Galvanization was performed to form an upper electrogalvanized layer containing Ni. In addition, the comparative example No. 19-No. 21
As for, the electrogalvanizing of the lower layer was not performed, and only the electrogalvanizing corresponding to the upper layer was performed. The above (A), (B) and
Chromate treatment under each of the three conditions shown in (C)
A chromate film was formed on the electrogalvanized layer.
Separately, a phosphate treatment was performed under the condition (3) used in Example 1 to form a phosphate treatment film on the electrogalvanized layer.
【００４４】上記の供試材のうち、上層側電気亜鉛めっ
き層上にクロメート皮膜を形成した供試材については実
施例１と同様の耐黒変性試験を行ない、また、上層側電
気亜鉛めっき層上にリン酸塩処理皮膜を形成した供試材
については、実施例１と同様のリン酸塩処理後の外観試
験を行なった。それらの結果を、めっき層の成分組成お
よび付着量とともに表３および表４に示す。表３および
表４によれば、本発明例Ｎｏ．１０〜Ｎｏ．１８はいず
れの条件でクロメート処理した場合でも優れた耐黒変性
を示し、また、リン酸塩処理後の外観にも優れている。Of the test materials described above, a test material having a chromate film formed on the upper electrogalvanized layer was subjected to the same blackening resistance test as in Example 1; With respect to the test material on which the phosphate treatment film was formed, an appearance test after the phosphate treatment was performed in the same manner as in Example 1. The results are shown in Tables 3 and 4 together with the component composition and the amount of the plating layer. According to Tables 3 and 4, the invention sample No. 10-No. No. 18 shows excellent blackening resistance even when subjected to chromate treatment under any conditions, and also has an excellent appearance after phosphate treatment.
【００４５】これに対して電気亜鉛めっき層が単層であ
る比較例Ｎｏ．１９〜Ｎｏ．２１は、めっき層中のＰｂ
含有量が１０ｐｐｍを超えているため耐黒変性が劣って
いる。比較例Ｎｏ．２２〜Ｎｏ．２４は、上層側電気亜
鉛めっき層のめっき付着量が０．５ｇ／ｍ2未満である
ため、クロメート処理条件によっては耐黒変性が劣って
いる。比較例Ｎｏ．２５〜Ｎｏ．２７は、上層側電気亜
鉛めっき層中のＰｂ含有量が１０ｐｐｍを超えているた
め、また、比較例Ｎｏ．２８〜３０は上層側電気亜鉛め
っき層中のＮｉ含有量が５０ｐｐｍ未満であるため、い
ずれも耐黒変性が劣っている。On the other hand, in Comparative Example No. 1 in which the electrogalvanized layer was a single layer. 19-No. 21 is Pb in the plating layer
Since the content exceeds 10 ppm, blackening resistance is inferior. Comparative Example No. 22-No. Sample No. 24 has an inferior blackening resistance depending on the chromate treatment conditions because the plating weight of the upper electrogalvanized layer is less than 0.5 g / m 2 . Comparative Example No. 25-No. In Comparative Example No. 27, the Pb content in the upper electrogalvanized layer exceeded 10 ppm. Nos. 28 to 30 are inferior in blackening resistance because the Ni content in the upper electrogalvanized layer is less than 50 ppm.
【００４６】比較例Ｎｏ．３１〜Ｎｏ．３３は、上層側
電気亜鉛層中のＮｉ含有量が７００ｐｐｍを超えている
ため、耐黒変性は良好であるもののリン酸処理後の外観
が劣っている。比較例Ｎｏ．３４〜Ｎｏ．３６は、リン
酸塩処理液中に含まれる亜鉛イオンが３．５ｇ／ｌ未満
であるためリン酸塩処理後の外観が劣っている。Comparative Example No. 31-No. In No. 33, the Ni content in the upper electrozinc layer exceeds 700 ppm, so that the blackening resistance is good, but the appearance after phosphoric acid treatment is inferior. Comparative Example No. 34-No. Sample No. 36 is inferior in appearance after phosphating because zinc ions contained in the phosphating solution are less than 3.5 g / l.
【００４７】[0047]
【表３】 [Table 3]
【００４８】[0048]
【表４】 [Table 4]
【００４９】[0049]
【発明の効果】以上述べたように本発明によれば、クロ
メート処理した場合の耐黒変性が優れ、しかもめっき皮
膜自体と化成処理後の外観が良好な電気亜鉛めっき鋼板
を安価に提供することができる。As described above, according to the present invention, there is provided an inexpensive electrogalvanized steel sheet having excellent resistance to blackening when subjected to chromate treatment and having good appearance of the plating film itself and after chemical conversion treatment. Can be.
【図面の簡単な説明】[Brief description of the drawings]
【図１】電気亜鉛めっき浴中のＮｉ濃度と、電気亜鉛め
っき層中のＰｂ含有量との関係を示すグラフFIG. 1 is a graph showing the relationship between the Ni concentration in an electrogalvanizing bath and the Pb content in an electrogalvanizing layer.
【図２】電気亜鉛めっき浴中のＰｂ濃度と電気亜鉛めっ
き層中のＰｂ含有量の関係を示すグラフFIG. 2 is a graph showing a relationship between a Pb concentration in an electrogalvanizing bath and a Pb content in an electrogalvanizing layer.
【図３】リン酸塩処理液中の亜鉛イオン濃度と処理後の
めっき鋼板表面の白色度（外観性）との関係を示すグラ
フFIG. 3 is a graph showing the relationship between the zinc ion concentration in a phosphating solution and the whiteness (appearance) of the surface of a plated steel sheet after the treatment.
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 4K023 AA01 AA15 AB28 BA06 DA06 DA07 DA08 4K024 AA05 AB01 BA03 BC01 CA01 DA03 DA04 DB04 GA02 4K026 AA02 BA06 BB01 CA17 EA07 EA08 EB03 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K023 AA01 AA15 AB28 BA06 DA06 DA07 DA08 4K024 AA05 AB01 BA03 BC01 CA01 DA03 DA04 DB04 GA02 4K026 AA02 BA06 BB01 CA17 EA07 EA08 EB03
Claims (5)
有量が５０〜７００ｐｐｍ、Ｐｂ含有量が１０ｐｐｍ以
下の電気亜鉛めっき層を形成したことを特徴とする耐黒
変性に優れ且つめっき皮膜の白色度と化成処理後の外観
が良好な電気亜鉛めっき鋼板。1. An electrogalvanized layer having a Ni content of 50 to 700 ppm and a Pb content of 10 ppm or less formed on at least one surface of a steel sheet. Electrogalvanized steel sheet with good degree and good appearance after chemical conversion treatment.
電気亜鉛めっき層を形成し、その上部にＮｉ含有量が５
０〜７００ｐｐｍ、Ｐｂ含有量が１０ｐｐｍ以下であっ
て、めっき付着量が０．５ｇ／ｍ2以上の上層側電気亜
鉛めっき層を形成したことを特徴とする耐黒変性に優れ
且つめっき皮膜の白色度と化成処理後の外観が良好な電
気亜鉛めっき鋼板。2. A lower electrogalvanized layer is formed on at least one surface of a steel sheet, and the Ni content is 5
0 to 700 ppm, the Pb content is 10 ppm or less, and the plating weight is 0.5 g / m 2 or more, and the upper electrogalvanized layer is formed. Electrogalvanized steel sheet with good degree and good appearance after chemical conversion treatment.
板の少なくとも一方の表面に、硫酸亜鉛を主成分とし、
Ｎｉイオン濃度が５０〜１００ｐｐｍ、不純物たるＰｂ
イオン濃度が０．２ｐｐｍ未満であって、Ｎｉイオン濃
度（ｐｐｍ）＞Ｐｂイオン濃度（ｐｐｍ）×５００を満
足する電気亜鉛めっき浴中で、通電用電極として貴金属
系不溶性電極を用いて電気亜鉛めっきを施すことによ
り、Ｎｉ含有量が５０〜７００ｐｐｍ、Ｐｂ含有量が１
０ｐｐｍ以下の電気亜鉛めっき層を形成することを特徴
とする、耐黒変性に優れ且つめっき皮膜の白色度と化成
処理後の外観が良好な電気亜鉛めっき鋼板の製造方法。3. In a continuous electrogalvanizing line, at least one surface of a steel sheet contains zinc sulfate as a main component,
Ni ion concentration of 50 to 100 ppm, impurity Pb
Electrogalvanizing using a noble metal-based insoluble electrode as a current-carrying electrode in an electrogalvanizing bath having an ion concentration of less than 0.2 ppm and satisfying Ni ion concentration (ppm)> Pb ion concentration (ppm) × 500. To give a Ni content of 50 to 700 ppm and a Pb content of 1
A method for producing an electrogalvanized steel sheet which is excellent in blackening resistance and has good whiteness of a plating film and good appearance after chemical conversion treatment, characterized by forming an electrogalvanized layer of 0 ppm or less.
板の少なくとも一方の表面に、電気亜鉛めっきを施して
下層側電気亜鉛めっき層を形成し、次いで、硫酸亜鉛を
主成分とし、Ｎｉイオン濃度が５０〜１００ｐｐｍ、不
純物たるＰｂイオン濃度が０．２ｐｐｍ未満であって、
Ｎｉイオン濃度（ｐｐｍ）＞Ｐｂイオン濃度（ｐｐｍ）
×５００を満足する電気亜鉛めっき浴中で、通電用電極
として貴金属系不溶性電極を用いて電気亜鉛めっきを施
すことにより、前記下層側電気亜鉛めっき層の上部にＮ
ｉ含有量が５０〜７００ｐｐｍ、Ｐｂ含有量が１０ｐｐ
ｍ以下であって、めっき付着量が０．５ｇ／ｍ2以上の
上層側電気亜鉛めっき層を形成することを特徴とする、
耐黒変性に優れ且つめっき皮膜の白色度と化成処理後の
外観が良好な電気亜鉛めっき鋼板の製造方法。4. In a continuous electrogalvanizing line, at least one surface of a steel sheet is electrogalvanized to form a lower electrogalvanized layer, and then zinc zinc sulfate as a main component and a Ni ion concentration of 50%. -100 ppm, the concentration of Pb ions as impurities is less than 0.2 ppm,
Ni ion concentration (ppm)> Pb ion concentration (ppm)
In an electrogalvanizing bath satisfying × 500, electroless galvanizing is performed using a noble metal-based insoluble electrode as a current-carrying electrode, so that N is formed on the lower electrogalvanizing layer.
i content 50-700ppm, Pb content 10pp
m or less, and forming an upper electrogalvanized layer having a plating adhesion amount of 0.5 g / m 2 or more,
A method for producing an electrogalvanized steel sheet having excellent resistance to blackening, good whiteness of a plating film and good appearance after chemical conversion treatment.
３．５ｇ／ｌ以上含まれるリン酸塩処理液で化成処理す
ることを特徴とする、請求項３または４に記載の耐黒変
性に優れ且つめっき皮膜の白色度と化成処理後の外観が
良好な電気亜鉛めっき鋼板の製造方法。5. The blackening resistance according to claim 3, wherein after electrogalvanizing, a chemical conversion treatment is performed with a phosphating solution containing zinc ions in the solution in an amount of 3.5 g / l or more. A method for producing an electrogalvanized steel sheet having excellent whiteness of a plating film and good appearance after a chemical conversion treatment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23011698A JP2000054186A (en) | 1998-07-31 | 1998-07-31 | Electrogalvanized steel sheet excellent in blackening- resistance and good in whiteness degree and appearance after chemical conversion treatment of plated film and its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23011698A JP2000054186A (en) | 1998-07-31 | 1998-07-31 | Electrogalvanized steel sheet excellent in blackening- resistance and good in whiteness degree and appearance after chemical conversion treatment of plated film and its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2000054186A true JP2000054186A (en) | 2000-02-22 |
Family
ID=16902832
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23011698A Pending JP2000054186A (en) | 1998-07-31 | 1998-07-31 | Electrogalvanized steel sheet excellent in blackening- resistance and good in whiteness degree and appearance after chemical conversion treatment of plated film and its production |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2000054186A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006057149A (en) * | 2004-08-20 | 2006-03-02 | Jfe Steel Kk | Phosphated galvanized-steel sheet superior in corrosion resistance and blackening resistance |
| JP2006265622A (en) * | 2005-03-23 | 2006-10-05 | Jfe Steel Kk | Surface treated steel sheet having excellent corrosion resistance and scratch resistance and method for producing the same |
| JP2011032528A (en) * | 2009-07-31 | 2011-02-17 | Jfe Steel Corp | Chemical conversion treated electrogalvanized steel sheet and method of manufacturing the same |
| CN103842559A (en) * | 2011-10-04 | 2014-06-04 | 杰富意钢铁株式会社 | Production method for zinc-electroplated steel sheets |
| JP2016094640A (en) * | 2014-11-13 | 2016-05-26 | Ｊｆｅスチール株式会社 | Method for manufacturing electrogalvanized steel sheet |
-
1998
- 1998-07-31 JP JP23011698A patent/JP2000054186A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006057149A (en) * | 2004-08-20 | 2006-03-02 | Jfe Steel Kk | Phosphated galvanized-steel sheet superior in corrosion resistance and blackening resistance |
| JP4492254B2 (en) * | 2004-08-20 | 2010-06-30 | Ｊｆｅスチール株式会社 | Phosphate-treated galvanized steel sheet with excellent corrosion resistance and blackening resistance |
| JP2006265622A (en) * | 2005-03-23 | 2006-10-05 | Jfe Steel Kk | Surface treated steel sheet having excellent corrosion resistance and scratch resistance and method for producing the same |
| JP2011032528A (en) * | 2009-07-31 | 2011-02-17 | Jfe Steel Corp | Chemical conversion treated electrogalvanized steel sheet and method of manufacturing the same |
| CN103842559A (en) * | 2011-10-04 | 2014-06-04 | 杰富意钢铁株式会社 | Production method for zinc-electroplated steel sheets |
| CN103842559B (en) * | 2011-10-04 | 2016-11-09 | 杰富意钢铁株式会社 | The manufacture method of plated steel sheet |
| JP2016094640A (en) * | 2014-11-13 | 2016-05-26 | Ｊｆｅスチール株式会社 | Method for manufacturing electrogalvanized steel sheet |
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