JP5042555B2 - Zinc-based plated steel sheet having a thin film primary anticorrosive coating layer with excellent surface conductivity and method for producing the same - Google Patents
Zinc-based plated steel sheet having a thin film primary anticorrosive coating layer with excellent surface conductivity and method for producing the same Download PDFInfo
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Description
本発明は、パソコン、音響、テレビ等の家電製品、複写機、プリンター、ファクシミリ等のＯＡ製品等に用いられる亜鉛系表面処理鋼板であって、家電製品やＯＡ製品組み立て後の鋼板部材のアース性、電磁波シールド性確保に必須となる鋼板表面の導電性に優れ、耐食性も兼ね備えた表面処理鋼板にかかわるものである。 The present invention is a zinc-based surface-treated steel sheet used for home appliances such as personal computers, sound and television, OA products such as copiers, printers, facsimiles, etc., and the grounding property of the steel sheet member after assembly of home appliances and OA products The present invention relates to a surface-treated steel sheet that has excellent electrical conductivity on the surface of the steel sheet, which is essential for ensuring electromagnetic shielding properties, and also has corrosion resistance.
従来から、亜鉛めっき鋼板表面にクロメート処理を施した表面処理鋼板は、広範囲な分野の工業製品に大量に使われてきた。この亜鉛めっき鋼板は、通常の大気環境下で使用される際に発生する亜鉛めっき層の白錆発生を抑制する能力が高く、さらには電子基板と鋼製部材との導電性確保が容易でアース性、磁気シールド性に優れる特徴を有していた。白錆発生抑制能が高いのは、クロメート皮膜が持つ亜鉛めっきに対する不働態化能と傷部に対する自己補修能が高いためと考えられている。また、導電性が良好なのは、クロメート処理層が薄く均一であるために導通端子との接触抵抗が低く抑えられているためである。 Conventionally, a surface-treated steel sheet obtained by subjecting the surface of a galvanized steel sheet to chromate treatment has been used in large quantities for industrial products in a wide range of fields. This galvanized steel sheet has a high ability to suppress the occurrence of white rust in the galvanized layer that occurs when used in a normal atmospheric environment. Furthermore, it is easy to ensure electrical conductivity between the electronic board and the steel member, and it is grounded. Characteristics and excellent magnetic shielding properties. The high white rust generation suppressing ability is thought to be because the chromate film has a high ability to passivate galvanizing and self-repair ability to scratches. Moreover, the conductivity is good because the chromate treatment layer is thin and uniform, and the contact resistance with the conduction terminal is kept low.
近年、素材に対する環境負荷物質、有害物質低減の要求が大きくなり、クロメート皮膜に使用されている６価クロムの使用制限の動きが進んでいる。６価クロムは、発ガン性が指摘される毒性物質であり、表面処理鋼板製造工程での排出規制や鋼板使用時の溶出に伴う健康被害が懸念される。 In recent years, demands for reducing environmentally hazardous substances and harmful substances for materials have increased, and movements to limit the use of hexavalent chromium used in chromate coatings are progressing. Hexavalent chromium is a toxic substance that is pointed out to be carcinogenic, and there are concerns about health hazards associated with emission regulations during the surface-treated steel sheet manufacturing process and elution when using steel sheets.
そこで本発明者らは、クロメートを全く使わない処理皮膜の開発を行ってきた（例えば、特許文献１参照）。特許文献１は、亜鉛めっき鋼板の表面に、防錆コーティング層を塗布する技術であり、耐食性の向上を図るために、リン酸やインヒビター成分を適宜添加したものである。この処理鋼板は、絶縁性の樹脂層を塗布するがゆえに耐食性には優れるものの表面導電性には劣るという欠点を有していた。従って、この特許文献１の防錆鋼板は、家電製品やOA製品等のアース性を重視する機器への適用については、十分な特性を有しているとはいえないのが現状であった。 Therefore, the present inventors have developed a treatment film that does not use chromate at all (for example, see Patent Document 1). Patent Document 1 is a technique for applying a rust-preventing coating layer to the surface of a galvanized steel sheet. In order to improve corrosion resistance, phosphoric acid and an inhibitor component are appropriately added. This treated steel sheet has the disadvantage that it is excellent in corrosion resistance because it is coated with an insulating resin layer, but is inferior in surface conductivity. Therefore, the rust-proof steel sheet of Patent Document 1 has not been able to be said to have sufficient characteristics for application to devices that place importance on grounding properties such as home appliances and OA products.
ここでアース性とは、電子部品から発生した電磁波や機器外部から来る電磁波により生じた鋼板表面の電位を、接地電位と同じくすることであり、このアース性が不足すると電子機器の誤動作や故障、雑音等の不具合が生じることになる。 Here, the grounding is to make the electric potential of the steel plate surface caused by electromagnetic waves generated from electronic parts and electromagnetic waves coming from outside the equipment the same as the ground potential. If this grounding is insufficient, malfunction or failure of electronic equipment, Problems such as noise will occur.
これまでの電子機器は、このアース性を確保するために鋼製の外箱・シャーシ等とビス止めを用いる例が一般的であった。この場合、ネジ穴部は鋼板の端面が露出するために、クロメート処理層の如何にかかわらず金属−金属接触による導通が容易に得られた。しかし、近年の電子機器の小型化や高性能化に伴い複雑な部品形状が増えて、ネジ留めが減少し、接合が鋼板表面同士の接触やかしめ接合、板バネによる接触となる例が増大した。この場合、めっき鋼板表面の接触抵抗が小さいことが重要であり、前述した絶縁性の樹脂皮膜を塗布した系ではアース性が不足することとなる。 Conventional electronic devices generally use steel outer boxes, chassis, etc. and screws to secure this grounding property. In this case, since the end face of the steel plate was exposed at the screw hole portion, conduction by metal-metal contact was easily obtained regardless of the chromate treatment layer. However, with the recent downsizing and higher performance of electronic devices, the complexity of component shapes has increased, screwing has decreased, and examples of joining between steel sheet surfaces, caulking, and leaf springs have increased. . In this case, it is important that the contact resistance on the surface of the plated steel sheet is small, and the grounding property is insufficient in the system coated with the insulating resin film described above.
このアース性を向上させる従来の技術として、特許文献２では、めっき層の表面にアース性を有する中間層を形成し、さらにその表層に有機樹脂層を形成するが、その有機樹脂層の被覆率を８０％以上とし、かつ鋼板の表面粗さを算術平均粗さＲａで１．０〜２．０μｍ、ろ波中心線うねりWcaで０．８μm以下に規定している。 As a conventional technique for improving the grounding property, in Patent Document 2, an intermediate layer having a grounding property is formed on the surface of the plating layer, and an organic resin layer is further formed on the surface layer. Is 80% or more, and the surface roughness of the steel sheet is specified to be 1.0 to 2.0 μm in terms of arithmetic average roughness Ra and 0.8 μm or less in terms of the filtered center line waviness Wca.
また、特許文献３は、めっきを施す原板の表面粗度を放電加工した調質圧延ロールの表面粗さRaとPPIを規定することで得ており、その結果得られた亜鉛めっき鋼板は耐食性を損なわずに導電性を確保する技術を開示している。 Moreover, patent document 3 is obtained by prescribing | regulating the surface roughness Ra and PPI of the temper rolling roll which carried out the electric discharge machining of the surface roughness of the original plate which carries out plating, and the galvanized steel plate obtained as a result has corrosion resistance. A technique for ensuring electrical conductivity without damage is disclosed.
さらに、特許文献４は、めっきを施す原板自身の表面粗さを、山カウント数とRaとで規定することで耐食性と導電性の両立を図っている。 Furthermore, patent document 4 is aiming at coexistence of corrosion resistance and electroconductivity by prescribing | regulating the surface roughness of the original plate | board itself which metal-plates with a peak count number and Ra.
しかしながら特許文献２から４はいずれも導電性の向上効果は認められるものの安定的に性能が発現することが無く、製造ラインによっては導電性が確保できない場合があり、より安定的に導電性を確保する技術の開発が望まれていた。 However, although Patent Documents 2 to 4 all show an effect of improving conductivity, performance does not appear stably, and conductivity may not be ensured depending on the production line, and the conductivity is more stably secured. Development of technology to do was desired.
クロメートフリー皮膜を塗布した亜鉛めっき鋼板は、コイル状の鋼板を連続的にめっき処理とクロメートフリー処理とを施して製造される。めっき方法は電気めっき法と溶融めっき法があり、前者は、Ｚｎイオンを含む水溶液中で電気化学的に亜鉛を析出させる技術であり、後者は、鋼板を溶融状態の金属亜鉛浴に浸漬させて成膜する技術である。めっきの表面形状は、電気めっき法の場合は、めっきの均一成膜性が高いので原板の表面形状が維持されるが、溶融めっき法ではレベリング性が高く、めっき後の調質圧延ロール形状の転写による形状付与が成されるのが一般である。めっきが施された鋼板は、その後後処理セクションで樹脂系や無機系のクロメートフリー皮膜、あるいはクロメート皮膜が塗布され焼き付け乾燥される。その後、コイルに巻き取られて製品となる。 A galvanized steel sheet coated with a chromate-free film is produced by continuously subjecting a coiled steel sheet to a plating process and a chromate-free process. There are two plating methods: electroplating and hot dipping. The former is a technique in which zinc is electrochemically deposited in an aqueous solution containing Zn ions. The latter is a method in which a steel sheet is immersed in a molten metal zinc bath. This is a technique for forming a film. In the case of electroplating, the surface shape of the plating is maintained because the uniform film forming property of the plating is high, but the surface shape of the original plate is maintained by the hot dipping method, and the temper rolling roll shape after plating is high. Generally, the shape is imparted by transfer. The plated steel sheet is then applied with a resin-based or inorganic chromate-free film or chromate film in the post-processing section, and then baked and dried. Thereafter, the product is wound around a coil.
このような製造工程で製造される亜鉛系めっき鋼板は、製造の工程で多数の金属ロールと接触することになるが、ロールによっては鋼板表面に比較的高い圧下力を付与することが多い。亜鉛めっきが施され、後処理セクションで塗装されるまでの間は、めっき表面に金属ロールが圧下されるとめっき表面の形状が変化する可能性が高い。亜鉛めっき金属は、マイクロビッカース硬度が約５０程度と軟質であるために、めっきの凸形状部は金属ロールにより圧潰されて平滑になることが多い。このような変形は、ミクロな領域で生じることから、ＪＩＳ Ｂ ０６５１で定義される触針式表面粗度測定機による計測では形状変化を十分に認識することが不可能なことが多い。さらにこのような圧潰形状になると、原板やめっき後の調質圧延で付与した粗度が変化してしまい、その薄膜一次防錆被覆層の表面被覆状態も変化することで十分な導電性を発現できなくなる。 A zinc-based plated steel sheet manufactured in such a manufacturing process comes into contact with a number of metal rolls in the manufacturing process, but depending on the roll, a relatively high rolling force is often applied to the steel sheet surface. There is a high possibility that the shape of the plating surface changes when the metal roll is squeezed onto the plating surface until the galvanization is performed and the galvanizing is applied. Since the galvanized metal is soft with a micro Vickers hardness of about 50, the convex portion of the plating is often crushed and smoothed by a metal roll. Since such deformation occurs in a microscopic region, it is often impossible to fully recognize the shape change by measurement with a stylus type surface roughness measuring instrument defined in JIS B 0651. Furthermore, when it becomes such a crushing shape, the roughness imparted by the temper rolling after plating or plating changes, and the surface coating state of the thin film primary anti-corrosion coating layer also changes to express sufficient conductivity become unable.
すなわち、連続めっき設備で亜鉛めっきと後処理を行う現行の製造工程において生じる、めっき表面凸部の圧潰による導電性の低下を回避することが課題である。 That is, it is a problem to avoid a decrease in conductivity due to crushing of the plating surface protrusion, which occurs in the current manufacturing process in which galvanization and post-processing are performed in a continuous plating facility.
発明者らは、クロメートフリー処理を施した亜鉛系めっき鋼板の導電性と耐食性を両立すべく鋭意検討した結果、亜鉛系めっき層表面の粗度を単にＪＩＳ Ｂ ０６０１で規定された粗度パラメータをＪＩＳ Ｂ ０６５１に規定される装置を用いて測定することで管理するのではなく、めっき凸部のミクロな領域の粗度を規定することで導電性と耐食性の両立が可能となることを見出した。さらには、凸部の粗度がある値以上にある部分の存在割合が、ある一定値以上になることも重要であることを見出した。本発明は、上記の知見に基づいて成されたものである。 As a result of intensive studies to achieve both the conductivity and corrosion resistance of the zinc-based plated steel sheet subjected to the chromate-free treatment, the inventors have determined that the roughness of the surface of the zinc-based plated layer is simply the roughness parameter defined in JIS B 0601. It was found that it is possible to achieve both conductivity and corrosion resistance by defining the roughness of the microscopic area of the plating convex portion, rather than managing it by measuring using the apparatus defined in JIS B 0651. . Furthermore, it has been found that it is also important that the proportion of the portion where the roughness of the convex portion is a certain value or more becomes a certain value or more. The present invention has been made based on the above findings.
すなわち、本発明の要旨は次のとおりである。
（１）ＪＩＳ Ｂ ０６５１で定義される触針式表面粗さ測定機で得られる、ＪＩＳ Ｂ ０６０１で定義される亜鉛めっき層表面の算術平均粗さＲａが０．３μｍ以上２．０μｍ以下、最大山高さＲｐが４．０μｍ以上２０．０μｍ以下である亜鉛系めっき鋼板において、Ｒｐの８０％以上の山部の評価長さ２０μｍの範囲を電子線三次元粗さ解析装置で測定して得られる算術平均粗さＲａ（山）が、触針式表面粗度測定機で得られる平均線を中心として±２０％の高さの部分の評価長さ２０μｍの範囲の電子線三次元粗さ解析装置で測定して得られる算術平均粗さＲａ（平均）に対して７０％以上であることを特徴とする、薄膜一次防錆被覆層付与後の表面導電性に優れた亜鉛系めっき鋼板。
That is, the gist of the present invention is as follows.
(1) The arithmetic average roughness Ra of the surface of the galvanized layer defined by JIS B 0601 obtained by a stylus type surface roughness measuring machine defined by JIS B 0651 is 0.3 μm or more and 2.0 μm or less, maximum In a zinc-based plated steel sheet having a peak height Rp of 4.0 μm or more and 20.0 μm or less, it is obtained by measuring an evaluation length range of 20 μm of a peak part of 80% or more of Rp with an electron beam three-dimensional roughness analyzer. An electron beam three-dimensional roughness analyzer with an arithmetic average roughness Ra (mountain) in the range of an evaluation length of 20 μm at a height of ± 20% centering on an average line obtained with a stylus type surface roughness measuring machine A zinc-based plated steel sheet excellent in surface conductivity after application of a thin film primary anticorrosive coating layer, characterized in that it is 70% or more with respect to the arithmetic average roughness Ra (average) obtained by measuring in step (1).
（２）触針式表面粗さ測定機で得られるＪＩＳ Ｂ ０６０１で定義されるＲｐの８０％以上の山部の評価長さ２０μｍの範囲を電子線三次元粗さ解析装置で測定して得られる算術平均粗さＲａ(山)が、触針式表面粗度測定機で得られる平均線を中心として±２０％の高さの部分の評価長さ２０μｍの範囲の電子線三次元粗さ解析装置で測定して得られる算術平均粗さＲａ（平均）の７０％未満である部分の面積が亜鉛めっき表面積全体に対して５％以下であることを特徴とする、上記（１）に記載の薄膜一次防錆被覆層付与後の表面導電性に優れた亜鉛系めっき鋼板。 (2) Obtained by measuring an evaluation length range of 20 μm of a peak portion of 80% or more of Rp defined by JIS B 0601 obtained with a stylus type surface roughness measuring instrument with an electron beam three-dimensional roughness analyzer. Electron beam three-dimensional roughness analysis in which the arithmetic average roughness Ra (mountain) is within the range of the evaluation length of 20 μm at the height of ± 20% centered on the average line obtained by the stylus type surface roughness measuring machine The area of a portion that is less than 70% of the arithmetic average roughness Ra (average) obtained by measuring with an apparatus is 5% or less with respect to the entire surface area of the galvanized surface, as described in (1) above A zinc-based plated steel sheet with excellent surface conductivity after the application of a thin primary rust-proof coating layer.
（３）触針式表面粗さ測定機で得られるＪＩＳ Ｂ ０６０１で定義されるＲｐの８０％以上の山部の評価長さ２０μｍの範囲を電子線三次元粗さ解析装置で測定して得られる算術平均粗さＲａ（山）が０．０３μｍ以上１．０μｍ以下であることを特徴とする上記（１）または（２）に記載の薄膜一次防錆被覆層付与後の表面導電性に優れた亜鉛系めっき鋼板。 (3) Obtained by measuring with an electron beam three-dimensional roughness analyzer the evaluation length range of 20 μm of the peak part of 80% or more of Rp defined by JIS B 0601 obtained with a stylus type surface roughness measuring instrument. The arithmetic average roughness Ra (mountain) is 0.03 μm or more and 1.0 μm or less, and is excellent in surface conductivity after the application of the thin film primary anticorrosive coating layer according to the above (1) or (2) Galvanized steel sheet.
（４）薄膜一次防錆被覆層として、平均膜厚さが０．２μｍ以上５．０μｍ以下であることを特徴とする上記（１）から（３）までのいずれか一つに記載の薄膜一次防錆被覆層付与後の表面導電性に優れた亜鉛系めっき鋼板。 (4) The thin film primary as described in any one of (1) to (3) above, wherein the thin film primary anticorrosive coating layer has an average film thickness of 0.2 μm or more and 5.0 μm or less. Zinc-based plated steel sheet with excellent surface conductivity after applying a rust-proof coating layer.
（５）鋼板に亜鉛系めっきを施し、次いで薄膜一次防錆皮膜層を形成して製造される亜鉛系めっき鋼板であり、ＪＩＳ Ｂ ０６５１で定義される触針式表面粗さ測定機で得られる、ＪＩＳ Ｂ ０６０１で定義される亜鉛めっき層表面の算術平均粗さＲａが０．３μｍ以上２．０μｍ以下、最大山高さＲｐが４．０μｍ以上２０．０μｍ以下である亜鉛系めっき鋼板であって、Ｒｐの８０％以上の山部の評価長さ２０μｍの範囲を電子線三次元粗さ解析装置で測定して得られる算術平均粗さＲａ（山）が、触針式表面粗度測定機で得られる平均線を中心として±２０％の高さの部分の評価長さ２０μｍの範囲の電子線三次元粗さ解析装置で測定して得られる算術平均粗さＲａ（平均）に対して７０％以上である、薄膜一次防錆被覆層付与後の表面導電性に優れた亜鉛系めっき鋼板を製造する方法であって、鋼板に亜鉛めっき層を形成してから薄膜一次防錆被覆層を形成するまでの間、搬送される鋼板に接触するピンチロールによりめっき表面に加わるロール１ｍｍ長さあたりの圧下力Ｆ（Ｎ/mm2）とＪＩＳ Ｚ ２２４４で測定されるめっき層のマイクロビッカース硬度ＭＨｖとの間に下記の式（１）を満足する関係が成立するよう、圧下力を制御することを特徴とする、薄膜一次防錆被覆層付与後の表面導電性に優れた亜鉛系めっき鋼板の製造方法。
Ｆ＜9.8065ＭＨｖ ×（Ｒ2−（Ｒ−ｈ×１０-3）2）0.5 式（１）
ここで、Ｒはロール半径（ｍｍ）、ｈはめっき鋼板のＲｐの値（μｍ）とする。
(5) A zinc-based plated steel sheet produced by applying zinc-based plating to a steel sheet and then forming a thin film primary rust preventive film layer, which is obtained with a stylus type surface roughness measuring machine defined in JIS B 0651. A galvanized steel sheet having an arithmetic average roughness Ra of 0.3 μm or more and 2.0 μm or less and a maximum peak height Rp of 4.0 μm or more and 20.0 μm or less as defined in JIS B 0601 The arithmetic average roughness Ra (mountain) obtained by measuring the evaluation length range of 20 μm of the peak part of 80% or more of Rp with an electron beam three-dimensional roughness analyzer is a stylus type surface roughness measuring machine. 70% with respect to arithmetic average roughness Ra (average) obtained by measuring with an electron beam three-dimensional roughness analyzer having an evaluation length of 20 μm in the range of ± 20% height centered on the obtained average line Surface conductivity after applying the thin film primary anticorrosive coating layer A method for producing a galvanized steel sheet having excellent resistance to the plating surface by a pinch roll that is in contact with the conveyed steel sheet from the formation of the galvanized layer to the formation of the primary anticorrosive coating layer on the steel sheet. Between the rolling force F (N / mm 2 ) per 1 mm length of the roll and the micro Vickers hardness MHv of the plating layer measured by JIS Z 2244 so that the following equation (1) is satisfied. A method for producing a zinc-based plated steel sheet having excellent surface conductivity after applying a thin film primary anticorrosive coating layer, characterized by controlling a rolling force.
F <9.8065MHv × (R 2 − (R−h × 10 −3 ) 2 ) 0.5 formula (1)
Here, R is the roll radius (mm), and h is the Rp value (μm) of the plated steel sheet.
本発明によれば、薄膜一次防錆被覆層の膜厚を厚くしても導電性が発現することから、耐食性との両立が達成される。さらに、厚膜にすることが可能であれば、耐食性のみではなく、プレス加工性や耐疵付性、耐アブレージョン性などの特性も向上する。さらに、本発明のめっき粗度を指標とした製造管理を行えば、種々のめっきラインでの製造においても安定的に導電性と耐食性とがバランスした亜鉛系めっき鋼板を製造することが可能となる。 According to the present invention, even if the film thickness of the thin film primary anticorrosion coating layer is increased, conductivity is exhibited, so that compatibility with corrosion resistance is achieved. Furthermore, if the thickness can be increased, not only corrosion resistance but also properties such as press workability, scratch resistance, and abrasion resistance are improved. Furthermore, if production management is performed using the plating roughness of the present invention as an index, it is possible to stably produce a zinc-based plated steel sheet in which conductivity and corrosion resistance are balanced even in production on various plating lines. .
以下、本発明の詳細とその限定理由を説明する。
本発明者らは、連続めっき設備で製造された亜鉛系めっき鋼板のめっき表面形状を詳細に観察した。電気亜鉛めっきラインで製造した電気亜鉛めっき鋼板の表面走査電子顕微鏡写真の例を図１に示す。めっき層は、調質圧延で付与された原板の凹凸に沿ってめっき層が形成され、そのめっき層表面は電気亜鉛めっき層自身の微細な結晶形態に起因する微細形状を有することを見出した。ところが、原板の凸部に形成されためっき層表面の微細な結晶形態に起因する形状は、圧潰により平滑化している部分があることを見出した。図中の暗いコントラストで示される矢印部である。この圧潰された部分の粗度は、ＪＩＳ Ｂ ０６５１で定義される触針式表面粗さ測定機では計測不能であった。すなわち、触針式表面粗さ測定機は、金属針を測定探子としているが、針先端部の曲率半径Ｒは５μｍ程度であり、図１のめっき結晶に起因する微細な結晶形態を検出することが出来なかった。そこで、この微細な結晶形態を計測する手法を鋭意検討した結果、走査電子顕微鏡型の三次元粗さ解析装置を用いればよいことが判明した。
The details of the present invention and the reasons for limitation will be described below.
The inventors of the present invention observed in detail the plated surface shape of a zinc-based plated steel sheet produced by a continuous plating facility. An example of a surface scanning electron micrograph of an electrogalvanized steel sheet produced by an electrogalvanizing line is shown in FIG. It has been found that the plating layer is formed along the irregularities of the original plate provided by temper rolling, and the surface of the plating layer has a fine shape due to the fine crystal form of the electrogalvanized layer itself. However, it has been found that the shape resulting from the fine crystal form on the surface of the plating layer formed on the convex portion of the original plate has a portion smoothed by crushing. It is an arrow part shown by the dark contrast in a figure. The roughness of the crushed part could not be measured with a stylus type surface roughness measuring machine defined in JIS B 0651. That is, the stylus type surface roughness measuring instrument uses a metal needle as a measurement probe, but the curvature radius R of the tip of the needle is about 5 μm, and a fine crystal form resulting from the plated crystal of FIG. 1 is detected. I couldn't. Thus, as a result of intensive studies on a technique for measuring the fine crystal form, it has been found that a scanning electron microscope type three-dimensional roughness analyzer may be used.
図２（ａ）〜図２（ｃ）は、エリオニクス株式会社製フィールドエミッション電子線三次元粗さ解析装置（ＥＲＡ−８９００ＦＥ）を用いて測定した結果である。本装置は、４チャンネルの二次電子線検出器を装備し、表面の凹凸を定量化することが可能な装置である。その結果、粗さ解析の分解能は、高さ方向が１ｎｍ、平面方向が１．２ｎｍと極めて高分解能であり、図１のめっき結晶の微細な形状を十分に測定可能であった。 FIG. 2A to FIG. 2C show the results of measurement using a field emission electron beam three-dimensional roughness analyzer (ERA-8900FE) manufactured by Elionix Corporation. This device is equipped with a 4-channel secondary electron beam detector and can quantify surface irregularities. As a result, the resolution of the roughness analysis was 1 nm in the height direction and 1.2 nm in the plane direction, and the fine shape of the plated crystal in FIG. 1 could be measured sufficiently.
図２（ａ）の写真は、４チャンネルの和信号の合成像であり、図中の暗いコントラストの部分（図中（１）のエリア）は、原板の凸部になっている領域で、めっき層が圧潰されて平滑化している。一方その周囲の部分は原板の凹部のエリアでめっき層の微細な結晶形態が維持されている。それぞれのエリアでの微細な形状を図２（ｂ）と図２（ｃ）に示した。 The photograph in FIG. 2A is a composite image of four-channel sum signals, and the dark contrast portion (area (1) in the drawing) in the drawing is an area that is a convex portion of the original plate. The layer is crushed and smoothed. On the other hand, in the surrounding area, the fine crystal form of the plating layer is maintained in the concave area of the original plate. The fine shape in each area is shown in FIGS. 2 (b) and 2 (c).
さらに、このデジタル画像データをもとに、局部的な領域での表面形状を定量化するために、評価長さ２０μｍの領域でのＲａの値を求めた。圧潰されている図２（ａ）の（１）のエリアのＲａは０．０２μｍで、それ以外の部分のＲａは０．０６μｍであった。すなわち、評価長さが２０μｍという極めて狭い範囲での粗度を測定することで、凸部で圧潰されている部分とそれ以外のめっき微細結晶が残っている部分でＲａが３倍近く異なり、粗度の差を明確に示すことが可能であった。 Furthermore, in order to quantify the surface shape in the local region based on the digital image data, the Ra value in the region having an evaluation length of 20 μm was obtained. The Ra in the area (1) in FIG. 2 (a) that was crushed was 0.02 μm, and the Ra in the other areas was 0.06 μm. That is, by measuring the roughness in an extremely narrow range of 20 μm in evaluation length, Ra is almost three times different between the portion crushed by the convex portion and the portion where the other plated fine crystals remain, It was possible to clearly show the difference in degree.
次に、このような原板凸部の微細な形状が薄膜一次防錆皮膜の表面被覆状態に及ぼす影響について詳細に検討した。原板凸部のめっき微細結晶が圧潰されていないめっき鋼板と圧潰されているめっき鋼板にそれぞれ水系ポリオレフィン樹脂塗料を１．２μm塗布し、その断面構造を走査電子顕微鏡で観察した。その結果を図３（ａ）と図３（ｂ）に示す。図３（ａ）の圧潰されていないめっき鋼板の樹脂被覆層は、原板凸部で薄くなり、さらにその部分のめっき層表面の微細結晶の凸部では樹脂被覆層が完全に被覆していない状況が観察された。一方、図３（ｂ）の原板凸部の圧潰されているめっきは、樹脂被覆層が薄くなりながらも完全に被覆していることがわかった。すなわち原板凸部のめっき層表面の微細結晶形態が存在すると、樹脂層の被覆性を低下させてめっき層を部分的に露出させる作用があることが判った。この露出部は、通電点となることから、鋼板同士の接触や、導電端子との接触で導電性が確保されることがわかった。一方、原板凸部のめっき層の微細形状が圧潰された部分は、絶縁性の樹脂皮膜が被覆しているために導電性が発現しないこともわかった。すなわち、電気亜鉛めっき鋼板の導電性を向上させるためには、原板の凹凸形状を制御するだけでは不十分であり、凸部のめっき層表面の微細結晶構造を残存させることが重要であることを見出した。 Next, the influence of the fine shape of the original plate protrusion on the surface covering state of the thin film primary anticorrosive film was examined in detail. 1.2 μm of a water-based polyolefin resin coating was applied to each of the plated steel sheet in which the plated fine crystals of the original plate convex part were not crushed and the crushed plated steel sheet, and the cross-sectional structure was observed with a scanning electron microscope. The results are shown in FIGS. 3 (a) and 3 (b). The resin coating layer of the non-crushed plated steel sheet in FIG. 3 (a) is thin at the original plate convex portion, and the resin coating layer is not completely covered by the fine crystal convex portion on the surface of the plated layer. Was observed. On the other hand, it was found that the crushed plating of the convex part of the original plate in FIG. 3 (b) was completely covered while the resin coating layer was thin. In other words, it has been found that the presence of a fine crystal form on the surface of the plating layer on the convex portion of the original plate has the effect of lowering the coverage of the resin layer and partially exposing the plating layer. Since this exposed part becomes an energization point, it was found that conductivity was ensured by contact between steel plates or contact with a conductive terminal. On the other hand, it was also found that the portion where the fine shape of the plating layer of the original plate convex portion was crushed was covered with the insulating resin film, so that the conductivity was not exhibited. In other words, in order to improve the conductivity of the electrogalvanized steel sheet, it is not sufficient to control the uneven shape of the original plate, and it is important to leave the fine crystal structure on the surface of the plating layer of the protrusions. I found it.
本発明は、このような技術的な知見に基づいてなされたものであり、原板凸部のめっき層表面微細形状の残存度を規定する指標として、凸部以外の部分の評価長さ２０μmのRａの値を基準として、原板凸部のRａの値が７０％以上であれば圧潰が生じていない、もしくは若干の圧潰はあるが導電性への影響は無いと判断した。 The present invention has been made on the basis of such technical knowledge, and as an index for prescribing the remaining degree of the plating layer surface fine shape of the convex part of the original plate, the evaluation length of the part other than the convex part is Ra of 20 μm. With reference to the above value, it was determined that if the Ra value of the original plate protrusion was 70% or more, there was no crushing, or there was some crushing but no influence on the conductivity.
次に、本発明の数値を限定した理由について述べる。
まず、通常の接触式粗度計で示されるめっき鋼板の表面粗度は、ＪＩＳ Ｂ ０６０１で定義される算術平均粗さＲａで０．３μｍ以上２．０μｍ以下とする。Ｒａが０．３μｍより小さいと薄膜一次防錆被覆層の表面被覆性が良好となり、耐食性の観点からは望ましいが導電性の観点からは好ましくなく、導電性と耐食性を両立する薄膜一次防錆被覆層厚さの設定が困難となる。一方、Ｒａが２．０μｍを超えると薄膜一次防錆皮膜の被覆性が極めて悪くなり、導電性は極めて良好となるが耐食性が悪化し、両者の両立する膜厚範囲が設定できなくなる。従ってＲａは０．３μｍ以上２．０μｍ以下とした。最大山高さＲｐもＲａと同様な理由により４．０μｍ以上２０．０μｍ以下とした。
Next, the reason why the numerical values of the present invention are limited will be described.
First, the surface roughness of the plated steel sheet shown by a normal contact-type roughness meter is 0.3 μm or more and 2.0 μm or less in terms of arithmetic average roughness Ra defined by JIS B 0601. When Ra is less than 0.3 μm, the surface coverage of the thin film primary anticorrosion coating layer is good, which is desirable from the viewpoint of corrosion resistance, but is not preferable from the viewpoint of conductivity, and is a thin film primary antirust coating that satisfies both conductivity and corrosion resistance. Setting the layer thickness becomes difficult. On the other hand, when Ra exceeds 2.0 μm, the covering property of the thin film primary rust preventive film becomes extremely poor and the conductivity becomes very good, but the corrosion resistance deteriorates, and it becomes impossible to set a film thickness range in which both are compatible. Therefore, Ra is set to 0.3 μm or more and 2.0 μm or less. The maximum peak height Rp is also set to 4.0 μm or more and 20.0 μm or less for the same reason as Ra.
亜鉛系めっき鋼板のめっき付着量は、５ｇ／ｍ2より小さいと鋼板に対する犠牲防食作用が不十分となり短期に赤錆が発生してしまい好ましくなく、３００ｇ／ｍ2以上は耐食性向上の効果が飽和し、めっきコストの増大やパウダリング状めっき剥離があり好ましくない。 Coating weight of the zinc-based plated steel sheet, 5 g / m 2 less than the sacrificial protection effect is not preferable would be red rust short insufficient occurs to the steel sheet, 300 g / m 2 or more saturated, the effect of improving corrosion resistance In addition, there is an increase in plating cost and powdering-like plating peeling, which is not preferable.
原板凸部のめっき微細結晶の形状を定義するため、Ｒｐの８０％以上の山部に注目しその部分の評価長さ２０μｍの範囲でのＲａを定義した。Ｒｐが８０％未満の部分は金属ロールとの接触が生じなく、また、評価長さ２０μｍより小さくすると測定の誤差が無視できなくなり２０μｍより大きいと原板凸部をはみ出して凹部を含んでしまう事がある為好ましくない。 In order to define the shape of the plated fine crystal on the convex portion of the original plate, attention was paid to a peak portion of 80% or more of Rp, and Ra in the range of the evaluation length of 20 μm was defined. When the Rp is less than 80%, contact with the metal roll does not occur, and if the evaluation length is less than 20 μm, the measurement error cannot be ignored. If the evaluation length is greater than 20 μm, the original plate protrusion may protrude and include a recess. Because there is, it is not preferable.
凸部以外の部分は平均線近傍の上下２０％の部分を代表値とした。その部分のＲａの値を基準値とし、原板凸部（山部）のＲａがその７０％以上の値であれば、金属ロールによる圧潰が無いかほとんど軽微であり、導電性と耐食性に影響を与えないことが判った。一方、その部分のＲａの値が７０％未満になると金属ロールによる圧潰が顕著であると判断した。 For the portions other than the convex portion, the upper and lower 20% portions near the average line were used as representative values. If the Ra value of the portion is the reference value and the Ra of the convex portion (crest portion) of the original plate is 70% or more, there is no or almost no crushing by the metal roll, which affects the conductivity and corrosion resistance. I knew that I would not give it. On the other hand, when the Ra value of the portion was less than 70%, it was judged that crushing by the metal roll was significant.
山部のＲａは、細かすぎると薄膜一次防錆被覆層で完全に被覆されてしまい表面導電性を発現することが無く、その下限を０．０３μｍとした。一方、Ｒａが大きすぎると皮膜の被覆率が下がり表面導電性は向上するが耐食性が悪化するので、その上限は１．０μｍとした。 If the Ra of the peak portion is too fine, it is completely covered with the thin film primary anticorrosive coating layer and does not exhibit surface conductivity, and its lower limit is set to 0.03 μm. On the other hand, if Ra is too large, the coverage of the film is lowered and the surface conductivity is improved, but the corrosion resistance is deteriorated. Therefore, the upper limit is set to 1.0 μm.
さらに、たとえ原板凸部で圧潰された部分（Ｒａが７０％未満）が存在しても、その部分の面積割合が亜鉛めっき表面積全体の５％以下であれば導電性と耐食性が両立した本発明材が得られることが判った。その面積が５％より大きくなると、圧潰部の特性が支配的となり導電性の低下が無視できない値となった。 Furthermore, even if a portion (Ra is less than 70%) that is crushed by the convex portion of the original plate is present, if the area ratio of the portion is 5% or less of the entire surface area of the galvanized surface, the present invention achieves both conductivity and corrosion resistance. It was found that the material was obtained. When the area was larger than 5%, the characteristics of the crushed portion became dominant, and the decrease in conductivity was a value that could not be ignored.
原板凸部の微細結晶形状を残存させるためには、種々の操業条件の最適化が要求されるが、もっとも重要であるのは、めっき後薄膜一次防錆被覆層が施されるまでの間に金属ロールによる強い圧下が成されないようにすることである。ロールが捲きつけロールであれば圧下力は小さく圧潰は生じないが、ロールと鋼板が線接触で接するピンチロールの場合には、圧下力の上限制御が必要となる。その際に、めっき層のビッカース硬度によって圧潰が生じないための上限が異なってくるが、めっき層の硬度は、電解条件や浴中の不純物濃度によって容易に変化することから、一律に金属ロールの圧下力を規定することは有効でない。本発明者らは、ロール圧下力の上限許容値を詳細に検討した結果、圧下力の上限を規定する関係式を見出した。すなわち、ロール１ｍｍ長さあたりの圧下力Ｆ（Ｎ/mm2）とＪＩＳ Ｚ ２２４４で測定されるめっき層のマイクロビッカース硬度ＭＨｖとするとき、次式であらわせる。
Ｆ＜9.8065ＭＨｖ ×（Ｒ2−（Ｒ−ｈ×１０-3）2）0.5 式（１）
ここで、Ｒはロール半径（ｍｍ）、ｈはめっき鋼板のＲｐの値（μｍ）とする。
In order to leave the fine crystal shape of the convex part of the original plate, optimization of various operating conditions is required, but the most important thing is the time until the thin film primary anticorrosive coating layer is applied after plating. It is to prevent strong reduction by the metal roll. If the roll is a rolling roll, the rolling force is small and no crushing occurs. However, in the case of a pinch roll in which the roll and the steel plate are in line contact, upper limit control of the rolling force is required. At that time, the upper limit for preventing crushing varies depending on the Vickers hardness of the plating layer, but the hardness of the plating layer easily changes depending on the electrolytic conditions and the impurity concentration in the bath. It is not effective to specify the rolling force. As a result of examining the upper limit allowable value of the roll rolling force in detail, the present inventors have found a relational expression that defines the upper limit of the rolling force. That is, when the rolling force F (N / mm 2 ) per 1 mm length of the roll and the micro Vickers hardness MHv of the plating layer measured by JIS Z 2244 are expressed by the following formula.
F <9.8065MHv × (R 2 − (R−h × 10 −3 ) 2 ) 0.5 formula (1)
Here, R is the roll radius (mm), and h is the Rp value (μm) of the plated steel sheet.
Ｆが式（１）の右辺の値より大きくなると、めっき層は圧潰してしまい好ましくない。右辺の値より小さければ、本発明で規定する凸部の形状を維持することが可能となる。式（１）において、純亜鉛めっきの標準的なＭＨｖを５０、ピンチロールの半径を１００ｍｍ、めっき鋼板のＲｐを１０μmとすると、右辺は６９３となる。一方、標準的なピンチロールの圧下力は、１０００〜３０００（N/mm2）程度であるので、通常の操業条件では圧下力が右辺より大きな値となってしまい圧潰が生じてしまう。そこで、本発明で見出した式（１）を満たすようなロール圧下力に制御することが必要となる。 When F is larger than the value on the right side of the formula (1), the plating layer is crushed, which is not preferable. If the value is smaller than the value on the right side, it is possible to maintain the shape of the convex portion defined in the present invention. In formula (1), if the standard MHv of pure zinc plating is 50, the radius of the pinch roll is 100 mm, and the Rp of the plated steel sheet is 10 μm, the right side is 693. On the other hand, the standard pinch roll has a rolling force of about 1000 to 3000 (N / mm 2 ), so that under normal operating conditions, the rolling force becomes a value larger than that on the right side, resulting in crushing. Therefore, it is necessary to control the roll rolling force so as to satisfy the formula (1) found in the present invention.
薄膜一次防錆皮膜は、導電性と耐食性を両立させる膜厚に設定することが重要であり、ＪＩＳ Ｂ ０６５１によるＲａが小さい原板ほど最適な膜厚は薄くすることが可能である。その値は特定することは出来ないが、Ｒａが０．３μｍの時には最低でも０．２μｍが必要で、一方Ｒａが２．０μｍの時には最大でも５．０μｍあればよい。従って下限上限膜厚をそれぞれ０．２μmと５．０μmとした。但し、その最適値は、原板形状、凸部の微細結晶の粗度Ｒａ、Ｒｐ、塗料種等の複数の因子の影響を受けるため色々な場合がある。 It is important to set the thin film primary rust preventive film to a film thickness that achieves both electrical conductivity and corrosion resistance, and the optimal film thickness can be reduced as the original plate has a smaller Ra according to JIS B 0651. Although the value cannot be specified, at least 0.2 μm is necessary when Ra is 0.3 μm, while 5.0 μm at most is sufficient when Ra is 2.0 μm. Therefore, the lower limit upper limit film thickness was set to 0.2 μm and 5.0 μm, respectively. However, the optimum value may be various because it is affected by a plurality of factors such as the original plate shape, the roughness Ra, Rp of the fine crystal of the convex portion, and the paint type.
薄膜一次防錆層の種類は、水性の各種樹脂、例えばアクリル系、オレフィン系、ウレタン系、スチレン系、フェノール系、ポリエステル系等いずれでもよく、また溶剤系のエポキシ系などでも良い。あるいは、無機系のシリカ系、水ガラス系、金属塩系（Ｚｒ、Ｔｉ、Ｃｅ、Ｍｏ、Ｍｎ酸化物系）でもよい。さらには有機無機複合のシランカップリング剤系でも良い。皮膜には、耐食性向上、耐黒変性向上を目的として、リン酸、インヒビター成分、Ｃｏ、Ｎｉ等の金属を添加しても良い。 The type of the thin film primary rust preventive layer may be any of various water-based resins, for example, acrylic, olefin, urethane, styrene, phenol, polyester, etc., or solvent-based epoxy. Alternatively, inorganic silica, water glass, or metal salt (Zr, Ti, Ce, Mo, Mn oxide) may be used. Furthermore, an organic-inorganic composite silane coupling agent system may be used. Metals such as phosphoric acid, inhibitor components, Co, and Ni may be added to the film for the purpose of improving corrosion resistance and blackening resistance.
薄膜一次防錆皮膜のみの一層処理で十分な性能を発現するが、さらに下地処理としてクロメートフリー下地処理を施すと、耐食性、塗膜密着性等の皮膜性能が一段と向上し望ましい。クロメートフリー下地処理剤としては、酸化Ｚｒ、酸化Ｔｉ、酸化Ｓｉ、酸化Ｃｅ、りん酸塩、シランカップリング剤などを選択可能である。付着量は０．００１ｇ／ｍ2以下では十分な性能を得ることが出来ず、０．５ｇ／ｍ2を超えると効果が飽和し密着力が返って減少するなどの弊害が顕在化する。 A single layer treatment of only the thin film primary anti-corrosion film produces sufficient performance. However, if a chromate-free undercoating is further applied as the undercoating, it is desirable that the film performance such as corrosion resistance and coating film adhesion is further improved. As the chromate-free base treatment agent, Zr oxide, Ti oxide, Si oxide, Ce oxide, phosphate, silane coupling agent and the like can be selected. If the adhesion amount is 0.001 g / m 2 or less, sufficient performance cannot be obtained, and if it exceeds 0.5 g / m 2 , the effect becomes saturated and the adverse effect such as reduction of the adhesion force becomes obvious.
次に、実施例をもとに本発明をより詳細に説明する。
電気亜鉛めっき鋼板は、次の条件で作製した。原板は、板厚０．８ｍｍの冷延鋼板を用いた。この原板の表面粗度は、連続焼鈍後のスキンパスミルで使用する圧延ロールのロール粗度を変えることで調整した。ロール粗度は、放電ダル法で付与した。この原板を電気亜鉛めっき設備を用いて電気亜鉛めっきを行った。電気亜鉛めっきは、酸性の硫酸亜鉛浴で電流密度は５０〜１００Ａ／ｄｍ2、ラインスピードは毎分５０〜１２０ｍであった。
Next, the present invention will be described in more detail based on examples.
The electrogalvanized steel sheet was produced under the following conditions. A cold rolled steel plate having a thickness of 0.8 mm was used as the original plate. The surface roughness of the original sheet was adjusted by changing the roll roughness of the rolling roll used in the skin pass mill after continuous annealing. The roll roughness was applied by a discharge dull method. This original plate was electrogalvanized using an electrogalvanization facility. Electrogalvanizing was an acidic zinc sulfate bath with a current density of 50-100 A / dm 2 and a line speed of 50-120 m / min.
溶融亜鉛めっき鋼板は、次の条件で作製した。原板は、板厚０．８ｍｍの冷延鋼板を用いた。この原板を溶融亜鉛めっき設備を用いて溶融亜鉛めっきした。亜鉛浴は、Ｚｎ−０．２重量％Ａｌで浴温４６０℃であった。水素-窒素還元雰囲気で８００℃まで還元処理した原板を板温４８０℃まで冷却した後浴に浸漬した。浸漬後２秒後に取り出し、窒素ガスでワイピングしてめっき付着量を制御した。ラインスピードは毎分１００ｍであった。めっき後インラインの調質圧延機で表面に粗度を付与した。 The hot dip galvanized steel sheet was produced under the following conditions. A cold rolled steel plate having a thickness of 0.8 mm was used as the original plate. This original plate was hot dip galvanized using a hot dip galvanizing facility. The zinc bath was Zn-0.2 wt% Al and the bath temperature was 460 ° C. The original plate reduced to 800 ° C. in a hydrogen-nitrogen reducing atmosphere was cooled to a plate temperature of 480 ° C. and then immersed in a bath. It was taken out 2 seconds after the immersion and wiped with nitrogen gas to control the amount of plating. The line speed was 100 meters per minute. After plating, roughness was imparted to the surface with an in-line temper rolling mill.
めっき表面形状の測定は、ＪＩＳ Ｂ ０６５１に従った。用いた装置は、触針式表面粗さ測定機の東京精密株式会社製サーフコム１４００Ａである。また微小領域の粗度は、エリオニクス株式会社製フィールドエミッション電子線三次元粗さ解析装置（ＥＲＡ−８９００ＦＥ）を用いて測定した。 The plating surface shape was measured according to JIS B 0651. The apparatus used is Surfcom 1400A manufactured by Tokyo Seimitsu Co., Ltd., which is a stylus type surface roughness measuring machine. Moreover, the roughness of the micro area | region was measured using the Elionix Co., Ltd. field emission electron beam three-dimensional roughness analyzer (ERA-8900FE).
めっき後塗装セクションまでの金属ロールの圧下力を開放から3000N/mmまで変化させて原板凸部の圧潰状態を変化させた。薄膜一次防錆皮膜は、ロールコーターで膜厚０．１から６μｍとなるように塗布し、乾燥炉で板温が１５０℃となるよう焼き付けた。樹脂系被覆用には、純水にポリオレフィン樹脂（「ハイテックS-7024」東邦化学株式会社製）を樹脂固形分濃度が２０重量％となるように添加し、さらにリン酸アンモニウムをリン酸イオン濃度で１ｇ／Ｌとなるように溶かし、水分散性シリカ（「スノーテックスＮ」日産化学株式会社製）を２５ｇ／Ｌ添加し、一次防錆被覆剤を得た。一方、無機樹脂系被覆用には、日本パーカライジング株式会社製「ＣＴ−Ｅ３００Ｎ」を用いた。無機系被覆用には、純水にジルコンフッ化水素酸を５０重量％、シランカップリング剤を５０重量％添加し、リン酸でｐＨを３．０に調整した一次防錆被覆剤を用いた。 The crushing state of the convex part of the original plate was changed by changing the rolling force of the metal roll from the open to 3000 N / mm after plating. The thin film primary rust preventive film was applied with a roll coater to a film thickness of 0.1 to 6 μm, and baked to a plate temperature of 150 ° C. in a drying furnace. For resin coating, polyolefin resin (“HITECH S-7024” manufactured by Toho Chemical Co., Ltd.) is added to pure water so that the resin solids concentration is 20% by weight, and ammonium phosphate is added to the phosphate ion concentration. Was dissolved to 1 g / L, and 25 g / L of water-dispersible silica (“Snowtex N” manufactured by Nissan Chemical Industries, Ltd.) was added to obtain a primary rust preventive coating. On the other hand, “CT-E300N” manufactured by Nippon Parkerizing Co., Ltd. was used for coating with inorganic resin. For inorganic coating, a primary rust-preventing coating agent in which 50% by weight of zircon hydrofluoric acid and 50% by weight of a silane coupling agent were added to pure water and the pH was adjusted to 3.0 with phosphoric acid was used.
得られた試験片の耐食性は、ＪＩＳ Ｚ ２３７１の塩水噴霧試験法で７２時間腐食させ、表面の白錆発生面積率で判断した。白錆発生が１％以下は◎、５％以下は○で合格とし、５％より多い場合は×で不合格とした。導電性の測定は、三菱化学株式会社製ＬＯＲＥＳＴＡ ＥＰ型で行った。接触子はＥＳＰタイプ（４探針式）で接触子先端は直径２ｍｍで端子間距離は５ｍｍとした。接触子荷重１．５Ｎ／本、試験電流１００ｍＡで、２０回異なる位置で測定し表面抵抗が１ｍΩ以下で通電する回数から判断した。２０回通電した場合は◎、１０回以上１９回通電した場合は○で合格とし、９回以下の場合は×で不合格とした。 The corrosion resistance of the obtained specimen was corroded for 72 hours by the salt spray test method of JIS Z 2371, and judged by the surface white rust generation area ratio. When the occurrence of white rust was 1% or less, ◎, 5% or less was accepted as ◯, and when it was more than 5%, it was judged as x. The conductivity was measured with a LORESTA EP type manufactured by Mitsubishi Chemical Corporation. The contact was an ESP type (4-probe type), the tip of the contact was 2 mm in diameter, and the distance between terminals was 5 mm. The contact load was 1.5 N / piece, the test current was 100 mA, the measurement was made 20 times, and the determination was made based on the number of energizations with a surface resistance of 1 mΩ or less. When energized 20 times, ◎, when energized 10 times or more and 19 times, passed with ○, and when it was 9 times or less, it was rejected with ×.
表１にめっき層表面性状、微小領域めっき層表面性状、表２にめっき付着量、薄膜一次防錆被覆層についての水準表を示す。実施例１〜３９が本発明材で、比較例１〜１０が比較例である。 Table 1 shows the surface properties of the plating layer and the surface properties of the micro-area plating layer, and Table 2 shows the level table for the amount of plating adhesion and the thin film primary anticorrosive coating layer. Examples 1 to 39 are materials of the present invention, and Comparative Examples 1 to 10 are comparative examples.
表３にＳＳＴ７２時間後の耐食性評価結果と表面導電性評価結果をまとめた。実施例１〜３９はいずれの水準においても耐食性、導電性共に良好で両者の性能が両立しており、一方、比較例１〜１０は、耐食性か導電性のどちらかが不良で両者の性能が両立していない。 Table 3 summarizes the corrosion resistance evaluation results and the surface conductivity evaluation results after 72 hours of SST. Examples 1 to 39 are good in both corrosion resistance and conductivity at both levels, and both performances are compatible. On the other hand, in Comparative Examples 1 to 10, either corrosion resistance or conductivity is poor and both performances are poor. It is not compatible.
本発明の亜鉛系めっき鋼板は、導電性と耐食性に優れた表面処理鋼板として利用することが出来る。特に表面導電性が要求される、複写機、ファクシミリ等のＯＡ機器の機体やパソコンケース、ＡＶ機器などアースを必要とする用途への適用が出来る。 The zinc-based plated steel sheet of the present invention can be used as a surface-treated steel sheet having excellent conductivity and corrosion resistance. In particular, it can be applied to applications requiring grounding, such as copiers, facsimile machines and other office equipment, personal computer cases, and AV equipment that require surface conductivity.
Claims (5)
Ｆ＜9.8065ＭＨｖ ×（Ｒ2−（Ｒ−ｈ×１０-3）2）0.5 式（１）
ここで、Ｒはロール半径（ｍｍ）、ｈはめっき鋼板のＲｐの値（μｍ）とする。 This is a zinc-based plated steel sheet manufactured by applying zinc-based plating to a steel sheet and then forming a thin film primary rust-preventive coating layer, which is obtained with a stylus type surface roughness measuring machine defined by JIS B 0651. A zinc-plated steel sheet having an arithmetic average roughness Ra of 0.3 to 2.0 μm and a maximum peak height Rp of 4.0 to 20.0 μm defined by 0601, wherein Rp is An arithmetic average roughness Ra (mountain) obtained by measuring an evaluation length of 20 μm or more of a peak part of 80% or more with an electron beam three-dimensional roughness analyzer is an average obtained by a stylus type surface roughness measuring machine. 70% or more with respect to the arithmetic average roughness Ra (average) obtained by measuring with an electron beam three-dimensional roughness analyzer having an evaluation length of 20 μm in the range of ± 20% height around the line Excellent surface conductivity after application of thin film primary anticorrosive coating layer A method of manufacturing a galvanized steel sheet, which is applied to a plating surface by a pinch roll that contacts a steel sheet to be conveyed during the period from the formation of a galvanized layer on the steel sheet until the formation of a primary anticorrosive coating layer. Rolling down so that a relationship satisfying the following formula (1) is established between the rolling force F (N / mm 2 ) per 1 mm length of the roll and the micro Vickers hardness MHv of the plating layer measured by JIS Z 2244 A method for producing a galvanized steel sheet having excellent surface conductivity after application of a thin film primary anticorrosive coating layer, characterized by controlling force.
F <9.8065MHv × (R 2 − (R−h × 10 −3 ) 2 ) 0.5 formula (1)
Here, R is the roll radius (mm), and h is the Rp value (μm) of the plated steel sheet.
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