JPS6148591A - Very thin tinned steel sheet having superior weldability - Google Patents

Abstract

PURPOSE:To manufacture a tinned steel sheet having superior weldability and corrosion resistance at a low cost by depositing P or a P-Fe alloy on the surface of a steel sheet, carrying out tinning, and forming a chromate film. CONSTITUTION:A steel sheet is electrolytically degreased and pickled with sulfuric acid by electrolysis or immersion. The steel sheet as a cathode and a carbon anode are put in a plating bath contg. phosphoric acid and sodium hypophosphite to deposit P by 0.5-30mg/m<2>, or a P-Fe alloy layer is formed by plating by 0.5-30mg/m<2> (expressed in terms of P). The steel sheet is then tinned by a known method by 300-1,500mg/m<2> and electric current is supplied to the steel sheet as a cathode in an aqueous soln. contg. CrO3 and sulfuric acid to deposit metallic Cr and to form a chromate film on the Cr by 1-30mg/m<2> (expressed in terms of Cr). A tinned steel sheet having superior weldability and corrosion resistance and capable of forming the body of a food can or the like is obtd.

Description

【発明の詳細な説明】 産業上の利用分野 本発明は溶接性能にすぐれ、且つ耐食性能にすぐれた低
コスト錫鍍金鋼板に関するもので、さらに詳しくは食缶
、報告等の容器胴部を溶接で接合する溶接缶用を主用途
とするメッキ鋼板に関するものである。[Detailed Description of the Invention] Industrial Application Field The present invention relates to a low-cost tin-plated steel sheet with excellent welding performance and corrosion resistance. This relates to plated steel sheets mainly used for welded cans to be joined.

従来の技術 従来から、容器の低コスト化のために種々の技術開発が
進められているが（例えば、特開昭５７−Ｉｆ（９０９
８，５７−２００５９２等）、低コスト化の主な方向は
製缶技術と素材技術の開発、改良に大別される。Conventional Technology Various technological developments have been carried out to reduce the cost of containers (for example, Japanese Patent Application Laid-open No. 57-If (909)).
8, 57-200592, etc.), the main directions for cost reduction can be roughly divided into the development and improvement of can manufacturing technology and material technology.

発明が解決すべき問題点 溶接接合は主に多量の錫を使用するハンダ接合にかわる
ものとして開発されたもので、ハンダ接合に必要とされ
る約２５番メッキ材（錫付着量２．８ｇ／ｒｒｆ−片面
）より少ない錫付着量で良好な接合部を得る事ができる
。錫はスードロニック溶接（商品名）によって代表され
るワイヤーシーム溶接に極めて有効であり、溶接時にβ
−５ｎ（フリーＳｎと通称されている）がメッキ鋼板表
面に０．１〜０．３ｇ１ｍ′以上存在すれば、良好な高
速ワイヤーシーム溶接性の得られる事が一般に知られて
いる。３ピース容器用材料は製缶前に塗装され、その後
缶胴部を接合する場合が多い。この塗装焼付過程で下地
の鋼板と錫メッキ層の錫が合金化反応を生じ、　ＦｅＳ
ｎ２を主体とする合金層が生成する。この合金層はβ−
３ｎに比して溶接性能に劣るので、塗装焼付時に生成す
るＦｅ−３ｎ合金の生成量を可及的に抑制する事が溶接
性能の向上に有効なβ−３ｎ量を多く保持する事につな
がるのである。この事は特に缶材の低コスト化をめざし
た低目付錫メッキ鋼板（以下ＬＴＳと略称する）におい
て特に重要である。Problems to be Solved by the Invention Welded joints were developed mainly as an alternative to solder joints that use a large amount of tin. It is possible to obtain a good joint with a smaller amount of tin adhesion than (rrf - one side). Tin is extremely effective for wire seam welding, represented by Suudronic welding (trade name), and
It is generally known that good high-speed wire seam weldability can be obtained if 0.1 to 0.3 g/m' or more of -5n (commonly called free Sn) is present on the surface of the plated steel sheet. Three-piece container materials are often painted before can manufacturing, and then the can body is joined. During this paint baking process, an alloying reaction occurs between the underlying steel plate and the tin in the tin plating layer, resulting in FeS
An alloy layer mainly composed of n2 is formed. This alloy layer is β-
Since the welding performance is inferior to 3n, suppressing the amount of Fe-3n alloy produced during paint baking will lead to maintaining a large amount of β-3n, which is effective in improving welding performance. It is. This is particularly important for low-density tin-plated steel sheets (hereinafter abbreviated as LTS), which aim to reduce the cost of can stock.

本発明は、このようなＬＴＳにおいて優れた溶接性をも
たらすメッキ鋼板を提供するものである。The present invention provides a plated steel sheet that provides excellent weldability in such LTS.

問題点を解決すべき手段・作用 本発明はこの鉄〜錫合金層の生成を有効に抑制する技術
を提供するもので、その特徴は、錫メッキに先立ち鋼板
表面にリン又はリン−鉄合金を析出せしめ、その後に錫
メッキ、更にクロメート皮膜又は金属クロムの上にクロ
メート皮膜を施すも！　　　　　　　　のである。Means and Effects to Solve the Problems The present invention provides a technique for effectively suppressing the formation of this iron-tin alloy layer, and is characterized by applying phosphorus or a phosphorus-iron alloy to the surface of the steel sheet prior to tin plating. Precipitate, then tin plating, and then apply a chromate film or a chromate film on top of metallic chromium! It is.

尚、本発明ではこのりんめっき下地鋼板について詳細に
述べるが、鉄〜リンめっき鋼板を下地にしても、またリ
ンをめっき後加熱拡散によりＦｅ−Ｐ合金化を行なって
も、同しく目的を達成するりＳができる。In the present invention, this phosphorus-plated base steel sheet will be described in detail, but the purpose can be achieved in the same way even if the base is an iron-phosphorus-plated steel sheet, or if Fe-P alloying is performed by heat diffusion after phosphorus plating. Sururi S can be done.

塗装焼付過程で生成する鉄〜錫合金層の生成を抑制する
メカニズムについては不明な点か多いが、メッキした段
階でのβ−３ｎ結晶の配向性について、Ｐプレメッキで
は（１０１）面、Ｆｅ−Ｐプレメッキでは（２００）面
が優先方位になりやすいが、加熱による鉄〜錫合金化抑
制効果程度は、原板鋼板表面に存在しているリン付着量
によってほぼ定まり、前述のメンキ方法の相異による抑
制効果の差は認められない。従って、この場合β−３ｎ
結晶の配向性は直接の関係はないと思われる。一方、鋼
板表面上に析出したリンは、塗装焼付後においても、は
ぼ焼付前の位置に存在し、錫層側への拡散は少ない。こ
のことから、Ｐは鉄〜錫の間に存在して、鉄の熱拡散反
応の何等かの障壁になるものと認められる。Although there are many unknowns about the mechanism that suppresses the formation of the iron-tin alloy layer generated during the paint baking process, regarding the orientation of β-3n crystals at the plating stage, P pre-plating has a (101) plane, Fe- In P pre-plating, the (200) plane tends to be the preferred orientation, but the degree of suppression of iron-tin alloying by heating is almost determined by the amount of phosphorus deposited on the surface of the original steel sheet, and is due to the difference in the coating method mentioned above. No difference in suppressive effect was observed. Therefore, in this case β-3n
There seems to be no direct relationship between crystal orientation. On the other hand, the phosphorus precipitated on the surface of the steel plate remains in the same position before baking even after the paint is baked, and there is little diffusion toward the tin layer side. From this, it is recognized that P exists between iron and tin and acts as some sort of barrier to the thermal diffusion reaction of iron.

更に本発明について詳述する。まず常法に従がい、電解
脱脂後、硫酸溶液中で電解、あるいは浸’？＋’ｉにて
酸洗した板厚Ｑ、２１ｍｍのローモ板（連鋳アルミキル
ト鋼）を用いて以Ｆの処理を行なった。リンめっきはリ
ン系２０ｇ／　９．、次亜リン酸ソーダ２０ｇ／ｉの水
溶液、浴温８０℃にて、被処理板を陰極にし、炭素電極
を陽極として、電流密度３０Ａ／ｄｍ２、通電時間１秒
にて５〜６ｍｇ、／ｒｒｅのリンを析出せしめる。又鉄
〜リンめっきは、硫酸第一鉄１５０ｇ／免、ｍ化第−・
鉄４５ｇ／９．、リン酸５０ｇ／　９−１亜すン酸４０
ｇ／’ｌの水溶液を用い、浴温６０°Ｃ１被処理板を陰
極とし、陽極には鉄板を用い、電流密度３０Ａ／ｄｍ２
、通電時間１．５〜３秒にてリン量として２．７〜８．
０ｍｇ／ｍ′になるＦｅ−Ｐ合金層、・、キを得られる
。Further, the present invention will be explained in detail. First, follow the conventional method, and after electrolytic degreasing, electrolysis or immersion in a sulfuric acid solution. The following process F was performed using a Romo plate (continuously cast aluminum quilt steel) with a plate thickness Q of 21 mm that had been pickled at +'i. Phosphorous plating is 20g/9. , an aqueous solution of 20 g/i of sodium hypophosphite at a bath temperature of 80°C, using the plate to be treated as a cathode and a carbon electrode as an anode, at a current density of 30 A/dm2 and a current application time of 1 second, 5 to 6 mg/rre. of phosphorus is precipitated. For iron to phosphorus plating, ferrous sulfate 150g/m,
Iron 45g/9. , Phosphoric acid 50g/9-1 Snous acid 40g
g/'l aqueous solution, bath temperature 60°C, treated plate as cathode, iron plate as anode, current density 30A/dm2.
, the amount of phosphorus is 2.7 to 8.
An Fe-P alloy layer of 0 mg/m' can be obtained.

以上の方法でリン系の下地処理を行なった鋼板に、公知
のフェロスタン浴で錫メンキを行なった。メッキ浴の温
度は４５℃、鋼板を陰極とし、陽極に錫板を用い、電流
密度５Ａ／ｄｍ’で３秒間電解１、て、約１．０ｇ／ｒ
ｎ′の錫メッキ板を得た。A steel plate that had been subjected to a phosphorus-based surface treatment using the above method was tin-plated using a known ferrostane bath. The temperature of the plating bath was 45°C, a steel plate was used as the cathode, a tin plate was used as the anode, and electrolysis was carried out for 3 seconds at a current density of 5 A/dm', and the electrolysis was carried out at approximately 1.0 g/r.
A tin-plated plate of n' was obtained.

更にその上にクロム系の処理を行なうが、例えば無水ク
ロム酸１００ｇ／　Ｉ！、、硫酸０．８ｇ／艷の水溶液
を用い、浴温４３℃、板を陰極とし、陽極に鉛〜錫合金
板を用いて、電流密度３０Ａ／ｄｒｎ２、通電時間０１
秒にて、金属クロム０．５〜２．５ｍｇ／ｍ２、クロム
水利酸化物７．７〜Ｉ０．８ｍｇ／　ｒｎ’　（クロム
としテ）ノクロ１、系皮膜を得ることができる。Furthermore, a chromium-based treatment is applied on top of this, for example, chromic anhydride 100g/I! ,, using an aqueous solution of sulfuric acid 0.8g/barrel, bath temperature 43℃, plate as cathode, lead-tin alloy plate as anode, current density 30A/drn2, current application time 01
In seconds, it is possible to obtain a film containing 0.5 to 2.5 mg/m2 of metallic chromium and 7.7 to 0.8 mg/m2 of chromium hydroxide oxide/rn' (chromium toshite).

この様な手順で得られた本発明による極薄錫メッキ鋼板
を電気オーブン中で２０５℃Ｘ１０分の熱処理を３回行
ない、熱処理による合金化錫量を電解剥離法にて測定し
た。図にその結果を示す。合金層はＦｅＳｎ２を主体と
するもので、図より明らかな様に、リンのプレメッキ量
がふえるに従って合金層の生成量が減少し、本発明の効
果が認められる。The ultra-thin tin-plated steel sheet according to the present invention obtained by such a procedure was heat-treated three times at 205° C. for 10 minutes in an electric oven, and the amount of tin alloyed by the heat treatment was measured by an electrolytic stripping method. The results are shown in the figure. The alloy layer is mainly composed of FeSn2, and as is clear from the figure, as the amount of pre-plating of phosphorus increases, the amount of the alloy layer formed decreases, and the effect of the present invention is recognized.

リン付着量は、合金化抑制作用の期待代によって、個々
に最適範囲を設定すれば良いが、通常、最適範囲は３〜
６ｍｇ／ｍ’である。０．５ｍｇ／ｍ２未満では発明の
効果が殆んど期待できない。一方リンの付着量をふやし
ていけば、合金化抑制効果は明確に認められるが、錫メ
ッキ層と鋼板との密着性が劣化する。このことはリン付
着量が３０ｍｇ／ｍ２を超えると特に著しくなる。The optimum range for the amount of phosphorus attached may be set individually depending on the expected level of alloying suppression effect, but usually the optimum range is 3 to 3.
6 mg/m'. If the amount is less than 0.5 mg/m2, hardly any effect of the invention can be expected. On the other hand, if the amount of phosphorus attached is increased, the effect of suppressing alloying is clearly recognized, but the adhesion between the tin plating layer and the steel sheet deteriorates. This becomes particularly noticeable when the amount of phosphorus attached exceeds 30 mg/m2.

錫メンキ量の下限は、重焼後のフリー錫量を最低限０．
１ｇ／ｒｒｆを安定して確保するためには０．３ｇ／ｍ
’以」二を必要とする。この上限値は技術的には特に限
定されるものではないが、本発明の主な目的がコストタ
ウンの見地から、低メッキ量の錫を用いて塗装時の空焼
における錫の合金化量を少なくする事により溶接性に有
利に作用するフリー錫を少なくとも０．１ｇ／ｍ’以上
確保する事にあるので、錫付着量の上限を１．５ｇ／ｍ
’とする。１．５ｇ／ｍ’超では、特に本発明の処理を
行なわなくても、重焼後のフリー錫量を３．３ｇ／ｍ’
以上にする事は容易である。The lower limit of the amount of tin coating is the amount of free tin after heavy firing, which is at least 0.
To stably secure 1g/rrf, 0.3g/m
Requires two. This upper limit value is not technically limited, but from the viewpoint of cost reduction, the main purpose of the present invention is to use a low plating amount of tin to reduce the alloying amount of tin during dry firing during painting. The goal is to secure at least 0.1 g/m' of free tin, which has an advantageous effect on weldability by reducing the amount, so the upper limit of the amount of tin deposited is set at 1.5 g/m'.
'. If it exceeds 1.5 g/m', the amount of free tin after heavy firing can be reduced to 3.3 g/m' even without performing the treatment of the present invention.
It is easy to do the above.

本発明における錫メッキは、基本的にはメッキ後の溶融
化処理（通常、リフロー処理と称する。）を行なわない
が、錫量が約１．０ｇ／ｍ’〜　１．５ｇ／ｍ’の範囲
では、リフロー処理によりメッキ表面か鏡面状の光沢を
呈し、塗装焼付を想定した空焼！　　　　　　後のフリ
ー錫量を０．１ｇ／ｍ’以上にする事も容易に可能であ
り、本発明の応用として充分実用可能である。Tin plating in the present invention basically does not involve melting treatment (usually referred to as reflow treatment) after plating, but the amount of tin is in the range of approximately 1.0 g/m' to 1.5 g/m'. Now, the plating surface exhibits a mirror-like luster through reflow treatment, and is air-baked to simulate paint baking! It is also easily possible to increase the subsequent free tin amount to 0.1 g/m' or more, and this is sufficiently practical as an application of the present invention.

最上層のクロム層は（金属クロム＋グロム水和酸化物）
またはクロム水和酸化物皮膜から構成されるもので、そ
の伺着量はクロム量として　１〜３０ｍｇ／ｍ２、更に
このましくは５〜１５ｍｇ／ｍ’が適当である。　１ｍ
ｇ／ｍ′未満では、クロム層の被覆性に乏しく、クロム
層に期待する耐食性能、塗料音着性能が不良である。３
０ｍｇ／ｒｒｉ’超ではフリー錫量が０．３ｇ／ｍ２以
、Ｌ存在しても高速シーム溶接時に溶接チリが発生する
ので好ましくない。クロム系被膜を得るには無水クロム
酸、無水クロム酸〜硫酸、硫酸塩、スルフォン酸類、弗
化物、塩化物等からなる電解クロム酸浴、あるいは通常
のブリキのケミカル工程で広く利用されている重クロム
酸塩系の浴が好適である。The top chromium layer is (metallic chromium + gromite hydrated oxide)
Alternatively, it is composed of a chromium hydrated oxide film, and the amount of chromium deposited is preferably 1 to 30 mg/m2, more preferably 5 to 15 mg/m'. 1m
If it is less than g/m', the coverage of the chromium layer is poor, and the corrosion resistance and paint adhesion performance expected of the chromium layer are poor. 3
If it exceeds 0 mg/rri', even if the free tin amount is 0.3 g/m2 or more, welding dust will occur during high-speed seam welding, which is not preferable. To obtain a chromium-based coating, an electrolytic chromic acid bath consisting of chromic anhydride, sulfuric acid, sulfates, sulfonic acids, fluorides, chlorides, etc., or a heavy-duty metal bath widely used in the chemical process of ordinary tinplates, etc. Chromate based baths are preferred.

次に本発明の実施例を比較例とともに示す。Next, examples of the present invention will be shown together with comparative examples.

溶接に先立ち、サンプルは全て２０５℃Ｘ１ｌ１分の空
焼きを３回行なったものを使用した。シーム溶接性はヌ
ードロニンク溶接機（商品名）を用い、溶接速度５０ｍ
／分、溶接電波の周波数４００Ｈｚ、加圧力４５ｋｇ、
ラップ１１０．５ｍｍで行なった。散りの発生かなく、
接合部強度がデュポン衝撃に酎えうる溶接条件範囲の十
分広いものをＯ１非常に狭い溶接条件範囲でｌ１能なも
のをΔ、適正溶接条件範囲の見出せないものを×と表示
した（注：デュポン衝撃条件５００ｇ、φ６．３ｍｍＸ
　５０ｃｍ）。Prior to welding, all samples were subjected to dry firing three times at 205° C. for 1 minute. Seam welding was performed using a Nudronink welding machine (trade name) at a welding speed of 50 m.
/min, welding radio wave frequency 400Hz, pressing force 45kg,
This was done with a wrap of 110.5 mm. No scattering,
Those with a sufficiently wide range of welding conditions that allow the joint strength to accommodate DuPont impact are indicated as O1. Those that are capable of l1 in a very narrow range of welding conditions are indicated as Δ, and those for which an appropriate welding condition range cannot be found are indicated as ×. (Note: DuPont Impact condition: 500g, φ6.3mmX
50cm).

ＵＣＣ性（アンターカットフィルム腐食性）は、めっき
板にエポキシフェノール系塗料を５５ｍｇ／ｄｒｎ’塗
布し、２１０°Ｏテｉｏ分間焼付けた後に、サンプル板
表面にクロス状にｒｂ　ｔｏ　ｇ、深さ１５終のナイフ
カットを入れ、クエン酸１．５％、食塩１．５％から成
る腐食液中に５０°Ｃで３日間浸漬し、力・ンｈ部から
の錆の拡がり程度をみたが、錆の全く認められないもの
をＯ１錆の拡がりが全面に広く生じているものをＸ、そ
の中間をΔとした。UCC property (undercut film corrosivity) was determined by applying 55 mg/drn' of epoxy phenol paint to the plated plate, baking it for 210 degrees, and applying a cross pattern on the surface of the sample plate to a depth of 15 mm. A final knife cut was made and the rust was immersed in a corrosive solution consisting of 1.5% citric acid and 1.5% common salt at 50°C for 3 days to see how much rust had spread from the force/h part. Those in which no O1 rust was observed were designated as X, and those in which O1 rust was widely spread over the entire surface were designated as X, and those in between were designated as Δ.

発明の効果 本発明によれば、溶接性を向上し、かつ耐腐食性にも優
れた缶材料となる等の効果が得られる。Effects of the Invention According to the present invention, effects such as improved weldability and a can material having excellent corrosion resistance can be obtained.

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

図面は、リン含有量と合金錫生成量の関係を示す説明図
表である。The drawing is an explanatory chart showing the relationship between phosphorus content and alloy tin production amount.

Claims (1)

【特許請求の範囲】 １、鋼帯表面に、リンまたはリン〜鉄合金メッキを行な
い、次いで極薄錫メッキ層を形成せしめ、更にその上に
クロメート皮膜又は金属クロムの上にクロメート皮膜を
形成せしめる事を特徴とする溶接性にすぐれた錫メッキ
鋼板。 ２、リンまたはリン〜鉄合金メッキ皮膜の量がリン付着
量として０．５〜３０ｍｇ／ｍ＾２、錫メッキ皮膜の量
が錫付着量として３００ｍｇ／ｍ＾２〜１５００ｍｇ／
ｍ＾２、クロムおよびまたはクロメート皮膜の厚みがク
ロム量として１〜３０ｍｇ／ｍ＾２である特許請求の範
囲第１項記載の溶接性にすぐれた錫メッキ鋼板。[Claims] 1. Plating phosphorus or a phosphorus-iron alloy on the surface of the steel strip, then forming an extremely thin tin plating layer, and then forming a chromate film or a chromate film on metallic chromium. A tin-plated steel sheet with excellent weldability. 2. The amount of phosphorus or phosphorus-iron alloy plating film is 0.5 to 30 mg/m^2 as the amount of phosphorus attached, and the amount of the tin plating film is 300 mg/m^2 to 1500 mg/m^2 as the amount of tin attached.
The tin-plated steel sheet with excellent weldability according to claim 1, wherein the thickness of the chromium and/or chromate film is 1 to 30 mg/m^2 in terms of chromium content.