【発明の詳細な説明】[Detailed description of the invention]
本発明は近年一般に飲料缶用に使用されている
イージーオープンエンド（以下EOEと称す）、エ
アゾール缶、王冠等の缶蓋としての適性に優れた
表面処理鋼板に関するものである。
製缶用表面処理鋼板としては一般に電気錫メツ
キ鋼板（以下ブリキと称す）、電解クロム酸処理
鋼板（以下TFS―CTと称す）が知られており、
缶胴用、缶ブタ用等広く使用されているが、
EOE用素材としてはアルミニウムが主に使用さ
れている。その理由はアルミニウムの方が鋼板よ
りも開缶性が優れているということ以外に、アル
ミニウム製EOEの方がブリキ製、TFS―CT製
EOEよりも、缶外面耐錆性、又一部の内容物、
例えば含塩物等を除けば、缶内面耐食性に優れて
いるということがある。
しかしアルミニウムはその精練に多大な電力を
要することにより鋼板よりも高価である。さて、
EOE用素材として要求される特性は、缶内面性
能として耐食性及び内容物中へのFeイオン溶出
防止作用であり、缶外面性能としてはEOEスコ
ア加工部やリベツト加工部等における耐錆性と美
観保持性である。通常、EOE素材は前記したよ
うに大部分がアルミでごく一部にブリキが、又缶
胴材にはブリキやTFS―CTがいずれも製缶前に
塗装され組合せ使用される。この素材を使つて製
缶メーカーやパツカーでEOEと缶胴とを巻き締
め加工する際缶内面に当るEOEや缶胴の塗膜に
誤つて疵をつけた場合、パツカーで内容物の変質
等が起こり好ましくない。内容物が例えば果実ジ
ユース等の場合は、周知のSn，Fe電位逆転現象
即ちSnがFeより先に溶出する現象が起こり、Sn
の犠牲陽極作用によりFeの溶出を防止するため
通常のブリキ製EOEで十分である。しかるに内
容物がコーラ、ビール等の炭酸飲料水である場
合、前記した電位逆転現象は起らないため、Sn
のFe溶出防止作用は起らず内容物中へのFeイオ
ンの溶出が進む。したがつて通常製缶メーカーで
はEOE材にブリキを充当する際は巻き締め加工
後補修塗装を行い不経済である。又EOEは先に
述べたように、通常塗装されて使用されるが、ス
コアー加工時、缶内面側の塗膜は直接疵はつかな
いが加工時の衝撃で細かな亀裂を生じ劣化するた
め、前述したと同じ理由で炭酸飲料水の場合には
必ず補修塗装を施こさねばならなかつた。
一方、EOEの外面性能としては、前述したよ
うに、EOEスコア加工部、リベツト加工部等に
おける耐錆性及び美観等が商品価値上、又衛生上
重要となる。EOEスコア加工部又リベツト加工
部等はEOE製造の際激しい衝撃加工を受け、塗
膜、メツキ層等が損傷し、特にブリキ製EOEの
場合、耐錆性が不良となるので、当然EOE製造
後補修塗装する必要があつた。
以上述べた如く、EOE素材として従来のアル
ミニウムやブリキでは、種々の問題点が多く、又
缶回収の面からもオールスチール缶の要求が強く
EOE適性に優れた、しかも安価な表面処理鋼板
の開発が各方面から要請されていた。
本発明者等はこれに応えて研究を進めた結果、
EOEとして缶内外面の耐食性を十分満足し補修
塗装が不要でしかも安価な全く新しいEOE用の
新表面処理鋼板を開発に成功したものである。
本発明の特徴とするところは、新規な表面処理
被覆構造にあり、具体的には、表面清浄化した鋼
板両面に設けたNi―Zn又はSn―Znの二元合金被
覆層と、該合金被覆層の少くとも一方の面に設け
たSn被覆層と、さらにその上層両面にクロム処
理層を有した被覆層構造から成る、従来公知の表
面処理鋼板とはその被覆形態を全く異にした
EOE、エアゾール缶、王冠等の缶蓋用に最適な
新素材である。
本発明の新表面処理鋼板の被覆構造を第１図に
模式的に示す。
１は素材となる冷延鋼板で、Ni―Zn又はSn―
Znの二元合金被覆層２が設けられている。この
二元合金被覆層２の上面にSn被覆層３が設けら
れているが、このSn被覆層は少くとも一方の面
に積層されておれば良く、もちろん両面重層構造
でも良い。説明の都合上、第１図では図面の上面
側を缶外面側に、下面側を缶内面側に使用するよ
うに描いたため、Sn被覆層３の下面側はかなら
ず存在するので実線で、又上面側のSn被覆層は
自由に選択し得るように破線で示した。４はクロ
ム処理、５は油膜層である。
本発明による新表面処理鋼板は種々な方法で製
造できるが、次にそのいくつかの製造法について
例示するが、勿論、この例示方法に限定されたり
制約されるものではない。
〔Ａ〕 Zn―Sn合金層及びZn―Sn合金層とSn層
の重層被覆法
(イ) 表面清浄化した冷延鋼板上にZn―Sn合金
メツキを施こした後Snメツキを行ない引続
きクロム酸処理及び塗油処理を行なう方法。
通常Zn―Sn合金メツキ及びSnメツキは電気
メツキ法、クロム酸処理は電解処理で行う
が、非電解処理で行うことも可能である。塗
油処理は通常静電塗油処理が行われる。
(ロ) 表面清浄化した冷延鋼板上に先ずZn単一
メツキを施した後Snメツキを重層させ引続
き加熱処理（例えばリフロー処理）でZn―
Sn合金層を形成させ、この合金層上にはSn
メツキは行わず直接(イ)と同じく、クロム酸処
理及び塗油処理を行う方法。但し、少くとも
片面側はZn―Sn合金層上にSn層を重層させ
る必要から、あらかじめSnメツキ層を厚く
したり、加熱処理条件を適当に選ぶことによ
りSn層を残すことが出来る。なお前記Zn，
Snメツキは通常電解処理で行うが、非電解
処理も可能である。
〔Ｂ〕 Zn―Ni合金層及びZn―Ni合金層とSn層
の重層被覆層
(イ) 表面清浄化した冷延鋼板上にZn―Ni合金
メツキを施した後(イ)と同じくSnメツキ、ク
ロム酸処理及び塗油処理を行なう方法。Zn
―Ni合金メツキ、Snメツキとも通常電解処
理で行うが非電解も可能。
(ニ) 表面清浄化した冷延鋼板上に先ずZn単一
メツキを施した後Niメツキを重層させ続く
加熱処理でZn―Ni合金化層を形成させた後、
(イ)と同じくSnメツキを行ない引続きクロム
酸処理及び塗油処理を行なう方法。Zn，Ni，
Sn各メツキとも通常電解処理で行うが非電
解処理も可能。
本発明は特に被覆層の構成が重要であり、特に
各層の数値限定の必要は無いが以下に好ましい数
値範囲を記述する。
Ni―Zn又はSn―Znの二元合金皮覆層は片面当
り0.5〜５ｇ／m2、Sn皮覆層は片面当り0.5〜11
ｇ／m2、クロム処理層は片面当り金属クロム換算
で２〜50mg／m2の範囲内にある場合が最も好まし
い結果が得られる。なお各被覆層は表裏同一付着
量に限定する必要はなく、必要用途により差厚メ
ツキも可能である。例えば缶内面側にはメツキ付
着厚を缶外面側より厚くすることも出来る。
本発明の新規な被覆層を有した新表面処理を
EOEを缶内面側に用いた場合、特にNi―Zn又は
Sn―Zn二元合金被覆系はその合金比率を最適に
調整すれば電気化学的に各種内容物中でFeより
わずかに陽極的になり、被覆層が製缶工程で損傷
しても疵部からのFeイオンの溶出を効果的に抑
制可能となるものである。
ここで、簡単になぜNi―Zn又はSn―Zn二元合
金被覆系がFeイオンの溶出を防止するかについ
てその理由を説明する。もし、Ni被覆単層とSn
被覆単層との重層の場合、Ni被覆層が電位的に
非常に貴であるためFeイオンの溶出防止効果は
なく、又Zn被覆単層とSn被覆単層の重層ではZn
被覆層が逆に非常に陽極的であるため、Feイオ
ン防止効果は大きくても、Znの溶出速度が早す
ぎてその効果が長期間持続しないことと、塗装後
の耐食性が劣化し不適当である。つまりNi―Zn，
Sn―Zn二元合金というようにZnとNi又はSnの比
率を適当に選んで合金化すれば、その電位がFe
よりわずかに陽極的となり、Feイオン溶出防止
効果を長期間安定して持続することが出来る点を
利用したものである。
一方、本発明の新表面処理をEOEの缶外面側
に用いた場合、Ni―Zn，Sn―Zn二元合金の働き
は、前記した缶内面側に用いたと同じ理由で製缶
時又は製缶後発生した塗膜及びメツキ欠陥部の
Fe露出部からの発錆を犠性防食作用によつて押
さえ得るし、合金比率を選択することにより、長
期間防食作用を持続することが出来るため、従来
必須であつたEOE製缶後の補修塗装が不必要と
なるか又は簡略化することが出来る。EOE外面
側にSn被膜層を二元合金層上に重層させるか否
かはその使用する用途例えばより高度の外面耐食
性が要求される場合、又Sn被覆層の色調を重要
視する場合等、適時選択すれば良い。
以上に述べたように、本発明のEOE用表面処
理鋼板を使用すれば、従来のブリキ製EOEの欠
点を補い、アルミニウム製EOEに近い性能を有
するので、アルミニウム製EOEから本素材を使
用したEOEへ転換すれば、大巾な製缶コストの
低減に役立つと共に缶回収の面より要請されるオ
ールスチール缶の製造が可能となるものである。
以上、主としてEOE用を例示して、本発明の表
面処理鋼板を説明したが、EOE用以外に、エア
ゾール缶の天地、王冠等特に加工損傷の影響を受
けやすい缶蓋用に適用すれば、EOE用と同様の
効果を得られるものである。
以下に本発明の具体実施例を述べる。
〔実施例 １〕
通常の方法で表面清浄化した鋼板両面に(1)に示
す条件でNi―Zn二元合金メツキを施し、その片
側面のみ(2)に示す条件でSnメツキを行つた。さ
らに(3)(4)に示す条件で、クロム処理層を形成させ
た。かかる後本発明メツキ鋼板両面に(5)に示す条
件で製缶用塗膜を形成させ、各種試験に供した。
(1) NiSO4・6H2O 100〜300ｇ／ 浴温 50℃
ZnSO4・6H2O 10〜50ｇ／
電流密度５〜20A／ｄm2
Na2SO4 100ｇ／
H3BO3 30ｇ／
(2) 流酸錫 25ｇ／ 浴温 40℃
フエノールスルフオン酸30ｇ／
電流密度20A／ｄm2
（65％溶液）
エトキシ化αナフトール
スルフオン酸 ２ｇ／
(3) Na2Cr2O7 25ｇ／
浴温 40〜70℃ 電流密度 10A／ｄm2
(4) CrO3 50ｇ／
H2SO4 0.4ｇ／（SO2- 4換算）
浴温 50℃ 電流密度 10〜40A／ｄm2
(5) エポキシ―フエノール系塗料
45mg／ｄm2塗布（片面当り乾燥重量）
205℃×10分焼付け
〔実施例 ２〕
通常の方法で表面清浄化した鋼板両面に(1)で示
す条件でSn―Zn合金メツキを施し、その片側面
のみに(2)に示す条件でSnメツキを行つた。さら
に(3)(4)に示す条件でクロム処理層を形成させた
後、本発明両面に(5)に示す条件で製缶用塗膜を形
成し、各種試験に供した。
(1) SnSO4 100〜300ｇ／
ZnSO4・6H2O 40〜150ｇ／ 浴温 50℃
Na2SO4 100ｇ／ 電流密度５〜10A／ｄ
m2
クエン酸 20ｇ／
(2)〜(5) 実施例１の(2)〜(5)と同じ
〔実施例 ３〕
通常の方法では表面清浄化した鋼板両面に(1)に
示す条件でZnメツキを施し、さらにその両面に
(2)に示す条件でSnメツキを表裏差厚で施した後、
(3)に示す条件でリフロー処理を行い、SnとZnを
合金化することによつて、鋼板片面（缶内面側）
にSn―Zn合金層とSn層の重層被覆、又他方の面
（缶外両側）はSn―Zn合金層のみを形成させた。
さらに(4)に示す条件でクロム処理層を形成させ
た後、本発明両面に(5)に示す条件で製缶用塗膜を
形成し、各種試験に供した。
(1) ZnSO4・6H2O 100〜300ｇ／ 浴温 50℃
Na2SO4 100ｇ／ 電流密度 20〜50A／ｄm2
(2) 実施例１の(2)と同じ
(3) ４ｇ／SnSO4−４ｇ／フエノールスルフ
オン酸のフラツクス中へdip後、直接通電によ
つて270℃まで急熱し、直ちに水中で急冷する。
(4) 実施例１の(4)に同じ
(5) 〃 〃 (5) 〃
試験項目としては以下に示す(A)〜(F)の項目を行
い、その性能を評価した。なお(A)〜(C)の項目は
EOE内面として必要な性能なので重層被覆面の
み行つたが、その他は重層被覆面Ni―Zn又はSn
―Zn単層被覆面両方について行つた。
(A) UCC（アンダーカツトコロージヨンテスト）
上記サンプルの塗膜に地鉄に達するスクラツチ
をナイフで入れた後、腐食液（1.5％クエン酸―
1.5％NaClの混合液）中に浸漬し、CO2ガスで飽
和させ、50℃で３日間保定した後、スクラツチ部
をテープ剥離してスクラツチ周辺部の腐食状態を
判定した。
(B) 腐食液浸漬テスト
上記サンプルにEOEスコア加工を行い、スコ
ア構側部（缶外面側）及び端面を密ロウでシール
した後缶内面側（重層面側）は無補修のまま脱気
した100％オレンジジユース、コーラ、ビール、
トマトジユース中に浸漬し、50℃×14日間保定後
の表面腐食状態を判定評価した。
(C) EOE内面適性テスト
(B)と同様なサンプルを、(b)と同様な塗装を施し
た＃25ETの塗装面に地鉄に達するスクラツチを
ナイフで入れたサンプルをコカコーラ中に浸漬、
電線で結合し、ガルバニツクカツプル対を形成さ
せたのち、CO2ガスの飽和を保ちつつ、28℃×10
日間保定した後、無抵抗電流計で測定した両者の
間に流れるガルバニツク電流値、及びコカコーラ
中へのFe溶出量でもつて評価した。
ここで電流値はFe陽極的（すなわちFe溶
出）、は陰極的となつていることを示す。
(D) 塗膜密着性テスト
上記サンプルをそのまま（１次密着性）、３％
NaCl溶液中に浸漬し、125℃×90分レトルト処理
した後（２次密着性）及び(A)のUCCテスト後
（UCC後密着性）、塗膜に２mm間隔のゴバン目を
ナイフで入れ、テープ剥離することによつて評価
した。
(E) 缶外面耐錆性テスト
上記サンプルの塗装面に地鉄に達するスクラツ
チをナイフで入れた後、50℃、RH98％の温潤テ
スターに6hrかけ、そして30℃RH80％の恒温、
恒湿テスターで１ケ月保定した後のスクラツチ部
からの発錆状態でもつて評価した。
(F) EOE外面適性テスト
上記サンプルにEOEスコア加工をした、スコ
ア構部を無補修のまま、QCテスターによつて
Wt30分―Dry60分（ただし水温20℃、エア50℃）
のサイクルを200cycleくり返した後のスコア構部
発錆状況によつて評価した。
以上(A)〜(F)の評価結果を第１表に示す。
The present invention relates to a surface-treated steel sheet that is highly suitable for can lids such as easy open ends (hereinafter referred to as EOE), aerosol cans, and caps that have been commonly used in recent years for beverage cans. Electrolytic tin-plated steel sheets (hereinafter referred to as tin plate) and electrolytic chromic acid treated steel sheets (hereinafter referred to as TFS-CT) are generally known as surface-treated steel sheets for can manufacturing.
It is widely used for can bodies, can lids, etc.
Aluminum is the main material used for EOE. The reason for this is that in addition to the fact that aluminum has better opening properties than steel plates, aluminum EOEs are better than those made from tinplate or TFS-CT.
The outer surface of the can is more resistant to rust than EOE, and some of the contents
For example, if salt-containing substances are excluded, the corrosion resistance of can interior surfaces is excellent. However, aluminum is more expensive than steel plate because it requires a large amount of electricity to refine. Now,
The characteristics required for EOE materials are corrosion resistance and prevention of Fe ion elution into the contents as the inner surface performance of the can, and rust resistance and aesthetic preservation in the EOE score processing area, rivet processing area, etc. as the outer surface performance of the can. It is gender. Normally, as mentioned above, the EOE material is mostly aluminum with a small portion made of tinplate, and the can body material is made of tinplate or TFS-CT, both of which are coated and used in combination before can manufacturing. If this material is used by a can manufacturer or a pack car to wrap the EOE and the can body, if the EOE on the inside of the can or the paint film on the can body is accidentally scratched, the contents may change in quality in the pack car. This is not a good thing to happen. When the contents are, for example, fruit juice, the well-known Sn and Fe potential reversal phenomenon, that is, the phenomenon in which Sn is eluted before Fe, occurs, and Sn
Ordinary tin EOE is sufficient to prevent Fe elution due to the sacrificial anode action. However, if the content is carbonated water such as cola or beer, the potential reversal phenomenon described above does not occur, so Sn
The effect of preventing Fe elution does not occur, and the elution of Fe ions into the contents proceeds. Therefore, when can manufacturers use tinplate as EOE material, they usually perform repair painting after seaming, which is uneconomical. Also, as mentioned earlier, EOE is usually used after being painted, but during scoring, the coating on the inside of the can is not directly damaged, but the impact during processing causes small cracks and deteriorates. For the same reason as mentioned above, carbonated drinks always had to be repainted. On the other hand, as for the external performance of EOE, as mentioned above, the rust resistance and aesthetic appearance of the EOE score processing area, rivet processing area, etc. are important for commercial value and hygiene. EOE score processed parts and rivet processed parts are subjected to severe impact processing during EOE manufacturing, which damages the paint film, plating layer, etc. Especially in the case of tinplate EOE, rust resistance becomes poor, so naturally after EOE manufacturing. It was necessary to repaint it. As mentioned above, there are many problems with conventional aluminum and tinplate as EOE materials, and there is a strong demand for all-steel cans from the perspective of can recovery.
There have been requests from various quarters for the development of surface-treated steel sheets with excellent EOE suitability and low cost. In response to this, the inventors conducted research and found that
We have succeeded in developing a completely new surface-treated steel sheet for EOE that satisfies corrosion resistance on the inside and outside of cans, does not require repainting, and is inexpensive. The feature of the present invention is a novel surface treatment coating structure, specifically, a binary alloy coating layer of Ni-Zn or Sn-Zn provided on both surfaces of a surface-cleaned steel plate, and the alloy coating layer. The coating form is completely different from conventionally known surface-treated steel sheets, which consists of a Sn coating layer on at least one side of the layer and a chromium treatment layer on both sides of the layer.
This new material is ideal for can lids such as EOE, aerosol cans, and crowns. The coating structure of the new surface-treated steel sheet of the present invention is schematically shown in FIG. 1 is a cold-rolled steel plate that is made of Ni-Zn or Sn-
A binary alloy coating layer 2 of Zn is provided. Although the Sn coating layer 3 is provided on the upper surface of the binary alloy coating layer 2, it is sufficient that the Sn coating layer is laminated on at least one surface, and of course, a double-sided multilayer structure may be used. For convenience of explanation, in Fig. 1, the upper side of the drawing is drawn to be used for the outer side of the can, and the lower side is used for the inner side of the can, so the lower side of the Sn coating layer 3 is always present, so it is shown as a solid line, and the upper side is shown as a solid line. The side Sn coating layer is indicated by a broken line so that it can be freely selected. 4 is a chromium treatment, and 5 is an oil film layer. The new surface-treated steel sheet according to the present invention can be manufactured by various methods, and some of the manufacturing methods will be illustrated below, but of course the method is not limited or restricted to these exemplified methods. [A] Multilayer coating method of Zn-Sn alloy layer and Zn-Sn alloy layer and Sn layer (a) Zn-Sn alloy plating is applied on the surface-cleaned cold rolled steel sheet, followed by Sn plating and then chromic acid coating. Methods of treatment and oiling.
Normally, Zn--Sn alloy plating and Sn plating are performed by electroplating, and chromic acid treatment is performed by electrolytic treatment, but it is also possible to perform non-electrolytic treatment. The oil application process is usually electrostatic oil application process. (b) First, Zn single plating is applied to the surface-cleaned cold-rolled steel sheet, and then Sn plating is layered and then heat treatment (for example, reflow treatment) is applied to Zn-
A Sn alloy layer is formed, and Sn
Method of directly applying chromic acid treatment and oiling treatment as in (a) without plating. However, since it is necessary to overlay the Sn layer on the Zn--Sn alloy layer on at least one side, the Sn layer can be left by making the Sn plating layer thicker in advance or by appropriately selecting the heat treatment conditions. Note that the Zn,
Sn plating is usually done by electrolytic treatment, but non-electrolytic treatment is also possible. [B] Zn-Ni alloy layer and multilayer coating layer of Zn-Ni alloy layer and Sn layer (a) After Zn-Ni alloy plating is applied to the surface-cleaned cold rolled steel sheet, Sn plating is applied as in (a), A method of chromic acid treatment and oil treatment. Zn
-Ni alloy plating and Sn plating are usually done by electrolytic treatment, but non-electrolytic treatment is also possible. (d) First, Zn single plating is applied to the surface-cleaned cold rolled steel sheet, and then Ni plating is layered and a Zn-Ni alloy layer is formed by subsequent heat treatment, and then
A method of performing Sn plating as in (a), followed by chromic acid treatment and oil coating. Zn, Ni,
Sn plating is usually done by electrolytic treatment, but non-electrolytic treatment is also possible. In the present invention, the structure of the coating layer is particularly important, and although there is no need to specifically limit the numerical values of each layer, preferred numerical ranges are described below. Binary alloy coating layer of Ni-Zn or Sn-Zn is 0.5 to 5 g/m 2 per side, Sn coating layer is 0.5 to 11 g/m 2 per side.
The most preferable results are obtained when the chromium-treated layer has an amount of 2 to 50 mg/m 2 in terms of metallic chromium per side. It should be noted that it is not necessary to limit each coating layer to the same amount of coating on the front and back sides, and plating with different thicknesses is also possible depending on the required application. For example, the plating thickness can be made thicker on the inner surface of the can than on the outer surface of the can. New surface treatment with the novel coating layer of the present invention
When EOE is used on the inner surface of the can, especially Ni-Zn or
If the Sn-Zn binary alloy coating system is adjusted to the optimum alloy ratio, it will electrochemically become slightly more anodic than Fe in various contents, and even if the coating layer is damaged during the can manufacturing process, it will not be damaged. This makes it possible to effectively suppress the elution of Fe ions. Here, we will briefly explain why the Ni--Zn or Sn--Zn binary alloy coating system prevents the elution of Fe ions. If Ni-coated single layer and Sn
In the case of a multilayer with a single coating layer, the Ni coating layer has a very noble potential, so it has no effect of preventing elution of Fe ions, and in the case of a multilayer with a single Zn coating layer and a single Sn coating layer, Zn
On the contrary, the coating layer is very anodic, so even though the effect of preventing Fe ions is great, the elution rate of Zn is too fast and the effect does not last for a long time, and the corrosion resistance after painting deteriorates, making it unsuitable. be. In other words, Ni―Zn,
If the ratio of Zn and Ni or Sn is appropriately selected and alloyed, such as a Sn-Zn binary alloy, the potential will change to Fe.
This method takes advantage of the fact that it is slightly more anodic and can stably maintain the effect of preventing Fe ion elution over a long period of time. On the other hand, when the new surface treatment of the present invention is applied to the outer surface of an EOE can, the Ni-Zn and Sn-Zn binary alloys do not function properly during can manufacturing for the same reason as when used on the inner surface of the can. Paint film and plating defects that occurred after
Rust formation from exposed Fe parts can be suppressed by sacrificial corrosion protection, and by selecting the alloy ratio, corrosion protection can be maintained for a long period of time, so repairs after EOE can manufacturing, which were previously essential. Painting becomes unnecessary or can be simplified. Whether or not to overlay the Sn coating layer on the binary alloy layer on the outer surface of the EOE depends on the application, for example, when a higher degree of external corrosion resistance is required, or when the color tone of the Sn coating layer is important, etc. All you have to do is choose. As mentioned above, if the surface-treated steel sheet for EOE of the present invention is used, it can compensate for the drawbacks of the conventional tin EOE and have performance close to that of aluminum EOE. Converting to this method will help significantly reduce can manufacturing costs, and will also make it possible to manufacture all-steel cans, which is required from the perspective of can recovery.
Above, the surface-treated steel sheet of the present invention has been explained mainly by exemplifying the use for EOE. However, if it is applied to can lids that are particularly susceptible to processing damage, such as the top, bottom, and crown of aerosol cans, it can be used for EOE. It is possible to obtain the same effect as using Specific examples of the present invention will be described below. [Example 1] Ni--Zn binary alloy plating was applied to both surfaces of a steel plate whose surface had been cleaned by a conventional method under the conditions shown in (1), and Sn plating was performed only on one side under the conditions shown in (2). Furthermore, a chromium-treated layer was formed under the conditions shown in (3) and (4). After that, a coating film for can making was formed on both sides of the plated steel sheet according to the present invention under the conditions shown in (5), and was subjected to various tests. (1) NiSO 4・6H 2 O 100-300g/ Bath temperature 50℃ ZnSO 4・6H 2 O 10-50g/
Current density 5-20A/dm 2 Na 2 SO 4 100g/ H 3 BO 3 30g/ (2) Tin sulfuric acid 25g/ Bath temperature 40℃ Phenolsulfonic acid 30g/
Current density 20A/dm 2 (65% solution) Ethoxylated α-naphthol sulfonic acid 2g/ (3) Na 2 Cr 2 O 7 25g/ Bath temperature 40-70℃ Current density 10A/dm 2 (4) CrO 3 50g/H 2 SO 4 0.4g/(SO 2-4 conversion ) Bath temperature 50℃ Current density 10~40A/dm 2 (5) Epoxy-phenol paint 45mg/dm 2 coated (dry weight per side) Baking at 205℃ x 10 minutes [Example 2] Sn--Zn alloy plating was applied to both sides of a steel plate whose surface had been cleaned by a conventional method under the conditions shown in (1), and Sn plating was applied only to one side under the conditions shown in (2). Furthermore, after forming a chromium treatment layer under the conditions shown in (3) and (4), a coating film for can making was formed on both sides of the present invention under the conditions shown in (5), and subjected to various tests. (1) SnSO 4 100-300g / ZnSO 4・6H 2 O 40-150g / Bath temperature 50℃ Na 2 SO 4 100g / Current density 5-10A/d
m 2 citric acid 20g/ (2) to (5) Same as (2) to (5) of Example 1 [Example 3] Zn was applied to both surfaces of the steel plate, which had been surface-cleaned in the normal method, under the conditions shown in (1). Plating is applied to both sides.
After applying Sn plating with different thicknesses on the front and back under the conditions shown in (2),
By performing reflow treatment under the conditions shown in (3) and alloying Sn and Zn, one side of the steel plate (inner side of the can)
A multilayer coating of a Sn--Zn alloy layer and a Sn layer was formed on the surface, and only a Sn--Zn alloy layer was formed on the other surface (both sides outside the can). Furthermore, after forming a chromium treatment layer under the conditions shown in (4), a coating film for can making was formed on both sides of the present invention under the conditions shown in (5), and subjected to various tests. (1) ZnSO 4・6H 2 O 100 to 300 g / Bath temperature 50℃ Na 2 SO 4 100 g / Current density 20 to 50 A/dm 2 (2) Same as (2) of Example 1 (3) 4 g / SnSO 4 After dipping into a flux of -4 g/phenolsulfonic acid, the sample was rapidly heated to 270°C by direct electric current, and immediately quenched in water. (4) Same as (4) of Example 1 (5) 〃 〃 (5) 〃 The following test items (A) to (F) were conducted and the performance was evaluated. Items (A) to (C) are
Only the multi-layer coated surface was tested because of the performance required for the inner surface of the EOE, but the other multi-layer coated surfaces were Ni-Zn or Sn.
- Both surfaces coated with a single Zn layer were tested. (A) UCC (Undercut Corrosion Test) After scratching the paint film of the above sample reaching the base metal with a knife, apply a corrosive solution (1.5% citric acid).
After immersing it in a 1.5% NaCl mixed solution), saturated with CO 2 gas, and maintaining it at 50°C for 3 days, the scratched area was peeled off with tape and the state of corrosion around the scratched area was determined. (B) Corrosive liquid immersion test The above sample was subjected to EOE score processing, and the score structure side (outer side of the can) and end face were sealed with wax, and then the inner side of the can (layered side) was degassed without any repairs. 100% orange juice, cola, beer,
The surface corrosion state after being immersed in tomato youth and kept at 50°C for 14 days was evaluated. (C) EOE internal aptitude test A sample similar to (B) was prepared by scratching the painted surface of #25ET with a knife that reached the base metal, and immersed it in Coca-Cola.
After connecting with electric wire to form a galvanic couple, heat at 28°C x 10°C while maintaining CO 2 gas saturation.
After being maintained for a day, the galvanic current flowing between the two was measured using a non-resistance ammeter, and the amount of Fe eluted into Coca-Cola was evaluated. Here, the current value indicates that Fe is anodic (that is, Fe elution), and current value is cathodic. (D) Paint film adhesion test The above sample as is (primary adhesion), 3%
After immersion in NaCl solution and retort treatment at 125°C for 90 minutes (secondary adhesion) and after the UCC test (A) (post-UCC adhesion), the coating film was made with a knife at 2 mm intervals. Evaluation was made by peeling off the tape. (E) Rust resistance test on the external surface of the can After scratching the painted surface of the above sample reaching the base metal with a knife, it was placed in a hot and humid tester at 50℃ and RH 98% for 6 hours, and then at a constant temperature of 30℃ and RH 80%.
The state of rust on the scratched area after being kept for one month using a humidity tester was also evaluated. (F) EOE external aptitude test The above sample was processed with an EOE score, and the score structure was left unrepaired by a QC tester.
Wt30 minutes - Dry60 minutes (water temperature 20℃, air 50℃)
Evaluation was made based on the score structure rusting status after repeating this cycle for 200 cycles. The evaluation results of (A) to (F) above are shown in Table 1.
【表】【table】
【表】
第１表本発明例１〜３はSn／Ni―Zn重層、４
〜６はSn／Sn―Zn重層、７，８はNi―Zn単層、
９，10はSn―Zn単層でEOE適性に優れている。
比較例１はSn／Zn単層で缶内面適性が著しく劣
り、又外面適性もZn特有の白錆を発生し好まし
くない。又比較例２はSn／Ni単層で評価(A)，(B)
には優れているが(C)のEOE内面適性及び(E)(F)
EOE外面適性がやや劣る。比較例３はSn／Ni―
Znであるがクロム処理層がなく、(A)(B)、又特に
(D)塗膜密着性が著しく劣る。比較例４，５はZn
及びNi単層の場合であり、それぞれEOE外面適
性で劣る。
以上述べた実施例からもわかるように、本発明
の新表面処理鋼板はEOE用素材として優れた性
能を有し、使用箇所に応じたメツキ構成となすこ
とにより多大の効果を得ることができる。[Table] Table 1 Invention Examples 1 to 3 are Sn/Ni-Zn multilayer, 4
~6 is Sn/Sn-Zn multilayer, 7 and 8 are Ni-Zn single layer,
9 and 10 are Sn-Zn single layers and have excellent EOE suitability.
Comparative Example 1 has a single layer of Sn/Zn, and is extremely poor in its suitability for the inside of the can, and its suitability for the outside is also unfavorable because white rust, which is characteristic of Zn, occurs. Comparative Example 2 was evaluated using a single layer of Sn/Ni (A), (B)
(C) EOE internal aptitude and (E) (F)
EOE external aptitude is slightly inferior. Comparative example 3 is Sn/Ni-
Zn but without chromium treatment layer, (A) (B), and especially
(D) Paint film adhesion is extremely poor. Comparative examples 4 and 5 are Zn
and Ni single layer, each of which is inferior in EOE external suitability. As can be seen from the examples described above, the new surface-treated steel sheet of the present invention has excellent performance as a material for EOE, and great effects can be obtained by configuring the plating structure according to the location of use.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図は本発明の新表面処理鋼板の１例を示す
模式的な断面図である。
１…冷延鋼板、２…Ni―Zn又はSn―Znの二元
合金被覆層、３…Sn被覆層、４…クロム処理層、
５…油膜層。
FIG. 1 is a schematic cross-sectional view showing one example of the new surface-treated steel sheet of the present invention. 1...Cold rolled steel plate, 2...Ni-Zn or Sn-Zn binary alloy coating layer, 3...Sn coating layer, 4...Chromium treatment layer,
5...Oil film layer.