JP3670805B2 - Manufacturing method of surface-treated steel sheet with excellent seam weldability, paint adhesion, and appearance - Google Patents
Manufacturing method of surface-treated steel sheet with excellent seam weldability, paint adhesion, and appearance Download PDFInfo
- Publication number
- JP3670805B2 JP3670805B2 JP17557997A JP17557997A JP3670805B2 JP 3670805 B2 JP3670805 B2 JP 3670805B2 JP 17557997 A JP17557997 A JP 17557997A JP 17557997 A JP17557997 A JP 17557997A JP 3670805 B2 JP3670805 B2 JP 3670805B2
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- Prior art keywords
- tin
- steel sheet
- chromium
- plating
- appearance
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Links
- 229910000831 Steel Inorganic materials 0.000 title claims description 40
- 239000010959 steel Substances 0.000 title claims description 40
- 239000003973 paint Substances 0.000 title claims description 13
- 238000004519 manufacturing process Methods 0.000 title claims description 10
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 49
- 238000007747 plating Methods 0.000 claims description 32
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 27
- 239000011651 chromium Substances 0.000 claims description 21
- 229910052804 chromium Inorganic materials 0.000 claims description 21
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 claims description 11
- 239000002245 particle Substances 0.000 claims description 11
- 239000011324 bead Substances 0.000 claims description 9
- 229910000423 chromium oxide Inorganic materials 0.000 claims description 9
- 150000004782 1-naphthols Chemical class 0.000 claims description 6
- 239000000654 additive Substances 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 6
- ZCDOYSPFYFSLEW-UHFFFAOYSA-N chromate(2-) Chemical compound [O-][Cr]([O-])(=O)=O ZCDOYSPFYFSLEW-UHFFFAOYSA-N 0.000 claims description 5
- 230000000996 additive effect Effects 0.000 claims description 4
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 claims description 3
- 230000002378 acidificating effect Effects 0.000 claims description 2
- 238000005282 brightening Methods 0.000 claims description 2
- 239000003795 chemical substances by application Substances 0.000 claims description 2
- 239000005029 tin-free steel Substances 0.000 description 19
- 239000011248 coating agent Substances 0.000 description 10
- 238000000576 coating method Methods 0.000 description 10
- 238000000034 method Methods 0.000 description 9
- 230000007797 corrosion Effects 0.000 description 7
- 238000005260 corrosion Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 230000002411 adverse Effects 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 235000013305 food Nutrition 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000002932 luster Substances 0.000 description 3
- 229910000640 Fe alloy Inorganic materials 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910001128 Sn alloy Inorganic materials 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 2
- 235000013361 beverage Nutrition 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000005238 degreasing Methods 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- -1 Ethoxy α-naphthol Chemical compound 0.000 description 1
- RMXTYBQNQCQHEU-UHFFFAOYSA-N ac1lawpn Chemical compound [Cr]#[Cr] RMXTYBQNQCQHEU-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- KJCVRFUGPWSIIH-UHFFFAOYSA-N alpha-naphthol Natural products C1=CC=C2C(O)=CC=CC2=C1 KJCVRFUGPWSIIH-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- SOCTUWSJJQCPFX-UHFFFAOYSA-N dichromate(2-) Chemical compound [O-][Cr](=O)(=O)O[Cr]([O-])(=O)=O SOCTUWSJJQCPFX-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000004381 surface treatment Methods 0.000 description 1
- AFNRRBXCCXDRPS-UHFFFAOYSA-N tin(ii) sulfide Chemical compound [Sn]=S AFNRRBXCCXDRPS-UHFFFAOYSA-N 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
- C23C28/32—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer
- C23C28/322—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one pure metallic layer only coatings of metal elements only
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
- C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
- C23C28/345—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer
- C23C28/3455—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one oxide layer with a refractory ceramic layer, e.g. refractory metal oxide, ZrO2, rare earth oxides or a thermal barrier system comprising at least one refractory oxide layer
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Inorganic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Ceramic Engineering (AREA)
- Electroplating Methods And Accessories (AREA)
- Other Surface Treatments For Metallic Materials (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、各種の食品、飲料及びその他の充填保存に適した溶接缶用の表面処理鋼板の製造方法に関するものである。
【０００２】
【従来の技術】
食品、飲料等に使用される容器用の材料としては、一般にブリキ、ティンフリー鋼板があり、また、最近は、錫メッキ量を低減した極錫メッキ鋼板（溶接性を確保するために、下地にＮｉメッキを施したものもある）、ニッケルメッキ鋼板等も材料コストを低減する目的から使用されている。
単にコスト的に見ると、ティンフリー鋼板がブリキは無論のこと、薄錫メッキ鋼板、ニッケルメッキ鋼板に比べて非常に優れている。また、塗料密着性、並びに塗装後耐食性においても、ティンフリー鋼板は非常に優れたもので、これらの特性に優れていることが、ティンフリー鋼板の需要が増大している理由でもある。
【０００３】
しかし、このティンフリー鋼板は、溶接性が悪いという非常に大きな欠点があり、現在は専ら接着法により製缶されたり、または、表層の金属クロム、クロム酸化物層を研削除去した後に溶接する溶接製缶法により製缶されている。したがって、ティンフリー鋼板の溶接性を改善することは非常に大きな産業的意味を持っている。ティンフリー鋼板の溶接性向上を図って種々の試みがなされており、例えばクロムメッキ鋼の下層に錫メッキし溶接性を改善したものとして、特公平２−１６３９７号公報、特公昭６１−１５１８号公報、特開昭５６−１２７７７６号公報、特開昭５６−４４７９３号公報がある。
【０００４】
【発明が解決しようとする課題】
しかしながら、これらはいずれもクロムメッキ層、並びにクロム水和酸化物層の絶縁性を改善して、溶接性を改善することを狙っており、接触抵抗を低下させるために必要とする下地錫メッキ量が多く、薄錫メッキ鋼板と同様、溶接性改善のために本来のティンフリー鋼板の特性を犠牲にしている。即ち、いずれもティンフリー鋼板の持つ本来の優れた特性である、金属光沢外観、優れた塗料密着性、並びに塗装後の耐食性を犠牲にしており、必ずしも優れた缶用の表面処理鋼板とはいえない。
特にティンフリーの持つ金属光沢との差異を問題視する需要家もあり、ティンフリーと全く同じ外観色調を確保できる表面処理鋼板が要求された。
【０００５】
【課題を解決するための手段】
本発明の要旨は次の通りである。
（１）被めっき鋼板の少なくとも片方の表面に、粒径０．４〜２．４μｍの粒状錫を２つ以上数珠状に連ねた数珠状錫を被めっき鋼板上に２〜２０％の面積率で形成し、少なくとも前記粒状錫に被覆されていない被めっき鋼板表面に３０〜１５０ｍｇ／ｍ2 の金属クロム層を形成し、その表面にさらにクロムとして２〜４０ｍｇ／ｍ2 のクロム酸化物層を形成することを特徴とするシーム溶接性、塗料密着性、外観に優れた表面処理鋼板の製造方法。
【０００６】
（２）被めっき鋼板の少なくとも片方の表面に、一般的に使用される光沢剤としての添加物を０．０５ｇ／ｌを超えて０．２０ｇ／ｌ未満の量を添加した酸性錫メッキ浴を用いて錫メッキを行い、粒径０．４〜２．４μｍの粒状錫を２つ以上数珠状に連ねた数珠状錫を鋼板上に２〜２０％の面積率で被覆し、次いで、通常のクロムメッキ、またはクロムメッキ及びクロメート処理によって、少なくとも前記粒状錫に被覆されていない被めっき鋼板表面に３０〜１５０ｍｇ／ｍ2 の金属クロムを被覆し、さらにその表面にクロムとして２〜４０ｍｇ／ｍ2 のクロム酸化物を被覆することを特徴とするシーム溶接性、塗料密着性、外観に優れた表面処理鋼板の製造方法。
（３）光沢剤としての添加物が、エトキシ化αナフトール、エトキシ化αナフトールスルフォン酸、のいずれかであることを特徴とする前記（１）または（２）に記載のシーム溶接性、塗料密着性、外観に優れた表面処理鋼板の製造方法にある。
【０００７】
以下、本発明について詳しく説明する。
本発明の基本は、下地の錫メッキを０．４〜２．４μｍの粒径にし、かつ、これらを数珠状に連ねて存在させることである。この後で、通常のティンフリー鋼板を製造する方法で鋼板の露出部分及び錫粒の上に金属クロム、さらにその上に、クロム水和酸化物被膜を生成させることで、本発明の目的とした表面処理鋼板が得られる。特に、本発明では、下地の錫メッキを０．４〜２．４μｍの粒状錫にし、かつ、これらを数珠状に連ねた構成とすることが非常に重要で、これが通常の錫メッキの如く、鋼板上に均一に薄くメッキされると（錫メッキの薄メッキの場合は島状にメッキされ、必ずしも均一の表面を覆うことはない。）、溶融加熱後、または、製缶行程での加熱によって、Ｓｎ／Ｆｅ合金が形成され溶接性の改善に寄与しなくなるほか、ティンフリー鋼板が持つ優れた金属光沢、及び塗装特性が損なわれることになる。
【０００８】
また、粒状錫を鋼板表面上に単一で散在させると、単一の錫粒と鋼板との密着性が十分でないため、粒状錫メッキ後クロムメッキまでの間に脱落しやすく、錫メッキ行程で錫メッキ量を一定に制御しても、クロムメッキ行程では下地メッキの粒状錫量にバラツキが生じ、付与された溶接性に大きなバラツキが生じ、品質管理が困難になる。そこで、これら粒状錫を数珠状に連ねることにより、鋼板と錫粒との密着性を確保し、安定した溶接性を確保することができる。また、数珠状に連なる錫粒の数の上限については、特に規定しない。これは、数珠状に連なる錫粒が増加しても、その他（溶接性、塗料密着性、外観）に悪影響を及ぼすことはない。
【０００９】
このように、錫粒を連ねるためには、通常錫メッキ浴中の光沢剤として添加されているエトキシ化α−ナフトールもしくはエトキシ化α−ナフトールスルホン酸等を０．０５ｇ／ｌを超えて０．２０ｇ／ｌ未満含有した錫メッキ浴が適している。添加量が０．０５ｇ／ｌ以下では、数珠状にならず、錫粒が単一で散在する。また、０．２０ｇ／ｌ以上添加すると錫が粒状にならず均一にメッキされ、製罐工程での加熱によってＳｎ／Ｆｅ合金が形成され溶接性に悪影響を与える。
【００１０】
本発明者らは、さらに鋭意検討した結果、錫粒の粒径を０．４μｍ以上、好ましくは、１μｍ以上とすることと、次いで２つ以上の錫粒が連なって数珠状になった数珠状錫の占める面積百分率については２％以上とすることで良好な溶接性を確保できることを見出した。ここで、面積百分率とは、被めっき鋼板表面の面積に対する、数珠状錫を被めっき鋼板表面に投影した面積の和の割合である。
【００１１】
次に、数珠状に連なる錫粒の占める面積百分率の上限について説明する。本発明者らが調査した結果によれば、錫粒径が０．４μｍであっても、数珠状錫の占める面積百分率が２０％を越えると、外観的に白くなるとともに、腐食挙動が、下地の錫粒の影響を受けて、ティンフリー鋼板の腐食挙動と異なるものになる。例えば、ティンフリー鋼板の場合硫黄を含む食品を内容物とした場合も、何ら問題はないが、錫メッキ鋼板の場合は、錫と硫黄が反応して黒色の硫化錫を生成して、缶内面が黒色に変化する。（硫化黒変と言われる）。このような硫化黒変が、数珠状錫の占める面積百分率が２０％超では認められる。また、塗膜下腐食も、錫メッキ特有の特性を示すようになることから、数珠状錫の占める面積百分率が２０％以下とする必要がある。また、錫の粒径が２．４μｍを越えると、鋼板表面との十分な密着力を確保することが困難になる。
【００１２】
次に、クロメート処理について説明する。クロムメッキ及びクロメート処理は、無水クロム酸系、重クロム酸塩系、クロム酸塩系浴中での陰極電解処理により行い、金属クロム被膜とその表面のクロム酸化物被膜からなる被膜を形成させるが、この付着量は、少なくとも前記粒状錫に被覆されていない被めっき鋼板表面において、それぞれ３０〜１５０ｍｇ／ｍ2 及び２〜４０ｍｇ／ｍ2 （クロム酸化物は金属クロム換算、いずれも片面当たり）とする。金属クロムが３０ｍｇ／ｍ2 未満ではティンフリーのメッキ外観が得られずさらに十分な耐食性を得ることができない。
【００１３】
また、金属クロムはその量の増大に伴ってティンフリーのメッキ外観、耐食性も向上するが、１５０ｍｇ／ｍ2 を越えると溶接性に悪影響を与えるためである。また、クロム酸化物が２ｍｇ未満では十分な塗膜密着性が得られず、クロム酸化物の増大に伴って塗膜密着性は向上するが４０ｍｇ／ｍ2 超になるとメッキ外観及び溶接性に悪影響を与える。
なお、金属クロム被膜もクロム酸化物被膜も粒状錫上の付着量は特性に殆ど影響しないため、限定しなくても良い。
【００１４】
【実施例】
次に、本発明の内容を実施例、比較例につき具体的に説明する。脱脂、酸洗、錫メッキ、クロムメッキ処理工程を有し、各工程の間に水洗い行程を有する連続メッキ設備を使用して、通常の方法によって冷間圧延、連続焼鈍、及び調質圧延された厚さ０．２３ｍｍの低炭素冷延鋼板に、通常の脱脂（ＮａＯＨ ５０ｇ／ｌ，６０℃，電流密度１０Ａ／ｄｍ2 で０．５秒の陰極電解処理），通常の酸洗（Ｈ2 ＳＯ4 ３０ｇ／ｌ，室温，電流密度１０Ａ／ｄｍ2 で０．５秒の陰極処理）を施した後、次の処理条件で錫メッキ、及びクロムメッキを行って、表１及び表２に示した１〜１０及び比較例１１〜１８の供試材を得、下記の評価項目について調査し、その結果を表１及び表２に示した。
【００１５】
【表１】
【表２】
・錫メッキ条件
（１）浴条件
Ｓｎ2+ ２０ｇ／ｌ
硫酸濃度 ６０ｇ／ｌ
添加剤 エトキシα-ナフトール ０〜０．３ｇ／ｌ
浴温度 ４０℃
Ｓｎ2+ ２０ｇ／ｌ
硫酸濃度 ６０ｇ／ｌ
添加剤 エトキシ化α−ナフトールスルホン酸 ０〜０．３ｇ／ｌ
浴温度 ４０℃
（２）電解条件
電流密度 ２Ａ／ｄｍ2
【００１８】
・クロムメッキ条件
（１）浴条件
ＣｒＯ3 １００ｇ／ｌ Ｈ2 ＳＯ4 １．２ｇ／ｌ
浴温度 ５０℃
（２）電解条件
電流密度 ５０Ａ／ｄｍ2
電気量 ５０Ｃ／ｄｍ2
【００１９】
・評価
（１）塗料密着性
供試材にエポキシフェノール系塗料を塗装焼き付け後（塗膜量５０ｍｇ／ｄｍ2 ）後、３．０％ＮａＣｌ溶液中で１１０℃×６０分のレトルト処理を実施した後、碁盤目にナイフで疵（１０×１０，幅１ｍｍ）を入れ、テープ剥離テストを実施した。
◎：剥離個数５個以下（合格、良好）
○：剥離個数６〜８個（合格、実用可能）
×：剥離個数９個以上（不合格）
【００２０】
（２）接触抵抗
供試材をまず、２１０℃×３０分の熱処理を行った後、５０ｍｍ平方に切断して１０枚の試料を準備し、この供試材２枚を重ね合わせ、電極径４．５ｍｍφの電極間に挟む。次いでこの電極間に５０ｋｇｆの加圧を加え、接触抵抗を測定し、上記試料から得た５つの測定データを平均値を調べた。
（電極間に流した電流は１．０００ｍＡ）
◎：５００μΩ未満（溶接性良）
○：５００μΩから７００μΩ未満（溶接性実用可能）
×：７００μΩ以上（溶接性不良）
【００２１】
（３）製品外観の評価
ティンフリー鋼板の外観を基準に目視で評価した。
◎：ティンフリー鋼板と同等レベル
○：ティンフリー鋼板とほぼ同等
×：ティンフリー鋼板と色が異なる
【００２２】
【発明の効果】
以上述べたように本発明によれば、ティンフリー鋼板の持つ外観を持ち、かつ溶接可能な、さらに塗料密着性に優れた鋼板を安易に得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a surface-treated steel sheet for a welding can suitable for various foods, beverages and other filling and storage.
[0002]
[Prior art]
In general, tin and tin-free steel plates are used as materials for containers used in food, beverages, etc. Recently, ultra-tin-plated steel plates with reduced tin plating (to ensure weldability, Some have been plated with Ni), and nickel-plated steel sheets are also used for the purpose of reducing material costs.
From a cost standpoint, tin-free steel sheets are of course superior to tin-plated steel sheets and nickel-plated steel sheets. In addition, tin-free steel sheets are also excellent in paint adhesion and post-coating corrosion resistance. These excellent characteristics are also the reason for increasing demand for tin-free steel sheets.
[0003]
However, this tin-free steel sheet has a very large defect that it has poor weldability. At present, the tin-free steel plate can be made exclusively by the bonding method or welded after grinding and removing the surface chromium metal and chromium oxide layer. Cans are made by the can-making method. Therefore, improving the weldability of the tin-free steel sheet has a great industrial significance. Various attempts have been made to improve the weldability of tin-free steel sheets. For example, Japanese Patent Publication No. 216397 and Japanese Patent Publication No. 61-1518 are disclosed in which the weldability is improved by tin-plating the lower layer of chromium-plated steel. Japanese Patent Laid-Open No. 56-127776 and Japanese Patent Laid-Open No. 56-44793.
[0004]
[Problems to be solved by the invention]
However, these are all aimed at improving the weldability by improving the insulation of the chromium plating layer and the chromium hydrated oxide layer, and the amount of underlying tin plating required to reduce the contact resistance As with thin tin-plated steel sheets, the characteristics of the original tin-free steel sheet are sacrificed to improve weldability. In other words, they all sacrifice the original excellent properties of tin-free steel plates, such as metallic luster appearance, excellent paint adhesion, and corrosion resistance after painting, and are not necessarily excellent surface-treated steel sheets for cans. Absent.
In particular, there are some customers who consider the difference from the metallic luster of tin-free as a problem, and a surface-treated steel sheet that can ensure the same appearance color tone as tin-free is required.
[0005]
[Means for Solving the Problems]
The gist of the present invention is as follows.
(1) An area ratio of 2 to 20% of beaded tin obtained by connecting two or more granular tins having a particle diameter of 0.4 to 2.4 μm in a bead shape on at least one surface of the steel plate to be plated. A metal chromium layer of 30 to 150 mg / m 2 is formed at least on the surface of the steel sheet to be plated that is not coated with the granular tin, and a chromium oxide layer of 2 to 40 mg / m 2 is further formed as chromium on the surface. A method for producing a surface-treated steel sheet excellent in seam weldability, paint adhesion, and appearance, characterized by forming.
[0006]
(2) An acidic tin plating bath in which an additive as a commonly used brightening agent is added in an amount of more than 0.05 g / l to less than 0.20 g / l on at least one surface of the steel sheet to be plated Using this method, tin plating is performed, and beaded tin in which two or more granular tins having a particle size of 0.4 to 2.4 μm are arranged in a bead shape is coated on a steel plate at an area ratio of 2 to 20%, chrome plating or by chromium plating and chromate treatment,, to 40 mg / m 2 covers at least the to-be-plated steel sheet surface not covered by the granular tin 30~150mg / m 2 metal chromium, further on its surface as a chromium A method for producing a surface-treated steel sheet excellent in seam weldability, paint adhesion, and appearance, characterized by covering with chromium oxide.
(3) The seam weldability and paint adhesion according to (1) or (2) above, wherein the additive as a brightener is either ethoxylated α-naphthol or ethoxylated α-naphthol sulfonic acid In the manufacturing method of the surface treatment steel plate excellent in property and appearance.
[0007]
The present invention will be described in detail below.
The basis of the present invention is to make the underlying tin plating have a particle size of 0.4 to 2.4 μm and to make these exist in a bead shape. After that, the object of the present invention was to form a chromium chromium hydrated oxide film on the exposed portion of the steel plate and the tin grains, and further a chromium hydrated oxide film on the exposed portion of the steel plate and tin grains by a method of manufacturing a normal tin-free steel plate A surface-treated steel sheet is obtained. In particular, in the present invention, it is very important that the underlying tin plating is granular tin of 0.4 to 2.4 μm and these are connected in a bead shape. When uniformly and thinly plated on a steel plate (in the case of tin plating, it is plated in an island shape and does not necessarily cover a uniform surface), after melting and heating, or by heating in the can manufacturing process The Sn / Fe alloy is not formed and does not contribute to the improvement of weldability, and the excellent metallic luster and coating properties of the tin-free steel plate are impaired.
[0008]
In addition, if granular tin is scattered on the surface of the steel sheet as a single piece, the adhesion between the single tin grain and the steel sheet is not sufficient. Even if the tin plating amount is controlled to be constant, the amount of granular tin in the base plating varies in the chromium plating process, and the given weldability varies greatly, making quality control difficult. Therefore, by connecting these granular tins in a bead shape, it is possible to ensure adhesion between the steel plate and the tin grains and to ensure stable weldability. Moreover, the upper limit of the number of tin grains connected in a bead shape is not particularly defined. This does not adversely affect the others (weldability, paint adhesion, appearance) even if the number of tin grains arranged in a bead shape increases.
[0009]
Thus, in order to link the tin grains, the amount of ethoxylated α-naphthol or ethoxylated α-naphthol sulfonic acid or the like usually added as a brightener in the tin plating bath exceeds 0.05 g / l to 0. A tin plating bath containing less than 20 g / l is suitable. When the addition amount is 0.05 g / l or less, it is not beaded and tin particles are scattered in a single manner. Further, when 0.20 g / l or more is added, tin is uniformly plated without becoming granular, and an Sn / Fe alloy is formed by heating in the iron making process, which adversely affects weldability.
[0010]
As a result of further intensive studies, the present inventors have determined that the particle size of the tin particles is 0.4 μm or more, preferably 1 μm or more, and then two or more tin particles are connected to form a rosary shape. It has been found that good weldability can be secured by setting the area percentage of tin to 2% or more. Here, the area percentage is the ratio of the sum of the areas where beaded tin is projected onto the surface of the steel sheet to be plated to the area of the surface of the steel sheet to be plated.
[0011]
Next, the upper limit of the area percentage occupied by the bead-shaped tin grains will be described. According to the results of investigation by the present inventors, even when the tin particle diameter is 0.4 μm, when the area percentage occupied by beaded tin exceeds 20%, the appearance becomes white and the corrosion behavior is Under the influence of tin grains, the corrosion behavior of tin-free steel sheets becomes different. For example, in the case of tin-free steel plate, there is no problem if the food containing sulfur is used as the contents, but in the case of tin-plated steel plate, tin and sulfur react to produce black tin sulfide, and the inner surface of the can Changes to black. (This is called sulfide blackening). Such sulfide blackening is observed when the area percentage occupied by beaded tin exceeds 20%. Moreover, since corrosion under a coating film also shows the characteristic peculiar to tin plating, it is necessary to make the area percentage which a beaded tin occupies 20% or less. On the other hand, if the particle size of tin exceeds 2.4 μm, it is difficult to ensure sufficient adhesion to the steel sheet surface.
[0012]
Next, the chromate process will be described. Chromium plating and chromate treatment are performed by cathodic electrolysis in a chromic anhydride, dichromate, or chromate bath to form a coating consisting of a metallic chromium coating and a chromium oxide coating on its surface. The adhesion amount is at least 30 to 150 mg / m 2 and 2 to 40 mg / m 2 (the chromium oxide is equivalent to metal chromium, both per one side) on the surface of the steel sheet not coated with the granular tin. To do. If the metallic chromium is less than 30 mg / m 2 , a tin-free plating appearance cannot be obtained and further sufficient corrosion resistance cannot be obtained.
[0013]
Further, metallic chromium improves the appearance of tin-free plating and corrosion resistance as the amount increases, but if it exceeds 150 mg / m 2 , it adversely affects weldability. Also, if the chromium oxide is less than 2 mg, sufficient coating film adhesion cannot be obtained, and the coating film adhesion improves as the chromium oxide increases, but if it exceeds 40 mg / m 2 , it adversely affects the plating appearance and weldability. give.
In addition, since the adhesion amount on a granular tin hardly influences a characteristic, it is not necessary to limit both a metal chromium film and a chromium oxide film.
[0014]
【Example】
Next, the contents of the present invention will be specifically described with reference to examples and comparative examples. It was cold-rolled, continuously annealed, and temper-rolled by ordinary methods, using continuous plating equipment that has degreasing, pickling, tin plating, and chrome plating processes, and a water washing process between each process. Low carbon cold-rolled steel sheet with a thickness of 0.23 mm was subjected to normal degreasing (cathodic electrolytic treatment of NaOH 50 g / l, 60 ° C., current density 10 A / dm 2 for 0.5 seconds), normal pickling (H 2 SO 4 After 30 g / l, room temperature, current density of 10 A / dm 2 for 0.5 seconds, tin plating and chrome plating were performed under the following processing conditions. The test materials of 1 to 10 and Comparative Examples 11 to 18 were obtained, the following evaluation items were investigated, and the results are shown in Tables 1 and 2.
[0015]
[Table 1]
[Table 2]
-Tin plating conditions (1) Bath conditions Sn 2+ 20 g / l
Sulfuric acid concentration 60g / l
Additives Ethoxy α-naphthol 0-0.3 g / l
Bath temperature 40 ° C
Sn 2+ 20g / l
Sulfuric acid concentration 60g / l
Additives Ethoxylated α-naphtholsulfonic acid 0-0.3 g / l
Bath temperature 40 ° C
(2) Electrolytic condition current density 2A / dm 2
[0018]
Chrome plating conditions (1) Bath conditions CrO 3 100 g / l H 2 SO 4 1.2 g / l
Bath temperature 50 ° C
(2) Electrolytic condition current density 50 A / dm 2
Electricity 50C / dm 2
[0019]
・ Evaluation (1) After coating and baking an epoxy phenolic paint on the paint adhesion test material (coating amount 50 mg / dm 2 ), a retort treatment was performed at 110 ° C. for 60 minutes in a 3.0% NaCl solution. After that, a scissors (10 × 10, width 1 mm) was put on the grid with a knife, and a tape peeling test was performed.
A: Number of peeled pieces 5 or less (pass, good)
○: Number of peeled pieces 6-8 (passed, practical)
X: Peeling number 9 or more (failed)
[0020]
(2) First, the contact resistance test material was heat-treated at 210 ° C. for 30 minutes, then cut into 50 mm squares to prepare 10 samples, and the two test materials were overlapped to obtain an electrode diameter of 4 Put between 5mmφ electrodes. Next, a pressure of 50 kgf was applied between the electrodes, the contact resistance was measured, and the average value of five measurement data obtained from the samples was examined.
(The current passed between the electrodes is 1.000 mA)
A: Less than 500 μΩ (good weldability)
○: 500 μΩ to less than 700 μΩ (Practical weldability)
×: 700 μΩ or more (poor weldability)
[0021]
(3) Evaluation of product appearance The appearance of the tin-free steel sheet was visually evaluated.
◎: Same level as tin-free steel plate ○: Almost equivalent to tin-free steel plate ×: Different color from tin-free steel plate [0022]
【The invention's effect】
As described above, according to the present invention, it is possible to easily obtain a steel plate having the appearance of a tin-free steel plate and capable of being welded and having excellent paint adhesion.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17557997A JP3670805B2 (en) | 1997-07-01 | 1997-07-01 | Manufacturing method of surface-treated steel sheet with excellent seam weldability, paint adhesion, and appearance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17557997A JP3670805B2 (en) | 1997-07-01 | 1997-07-01 | Manufacturing method of surface-treated steel sheet with excellent seam weldability, paint adhesion, and appearance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1121698A JPH1121698A (en) | 1999-01-26 |
| JP3670805B2 true JP3670805B2 (en) | 2005-07-13 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17557997A Expired - Fee Related JP3670805B2 (en) | 1997-07-01 | 1997-07-01 | Manufacturing method of surface-treated steel sheet with excellent seam weldability, paint adhesion, and appearance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3670805B2 (en) |
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- 1997-07-01 JP JP17557997A patent/JP3670805B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH1121698A (en) | 1999-01-26 |
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