JP4262826B2

JP4262826B2 - Aluminum alloy laminate coating material for can body and manufacturing method thereof

Info

Publication number: JP4262826B2
Application number: JP11322299A
Authority: JP
Inventors: 覚鈴木; 時彦小林; 了東海林
Original assignee: Furukawa Sky Aluminum Corp
Current assignee: Furukawa Sky Aluminum Corp
Priority date: 1998-04-28
Filing date: 1999-04-21
Publication date: 2009-05-13
Anticipated expiration: 2019-04-21
Also published as: JP2000026995A

Description

【０００１】
【発明の属する技術分野】
本発明は、熱可塑性樹脂フィルムの密着性が優れたキャンボディ用アルミニウム合金ラミネート被覆材およびその製造方法に関する。
【０００２】
【従来の技術】
飲料用缶には缶胴、缶蓋、底蓋からなる３ピース缶と缶胴と底蓋が一体となった缶体と缶蓋の２つからなる２ピース缶がある。このうち２ピース缶の缶体には絞りしごき缶（ＤＩ缶）と絞り再絞り缶（ＤＲＤ缶）が多く用いられ、最近は絞り後ストレッチ加工を施す薄肉化再絞り缶も開発されている。ところで、ＤＩ缶の製造では、従来、缶体成型後に、潤滑剤の洗浄、乾燥、塗装などの諸工程を行っていたが、近年、生産性向上および作業環境改善を目的に、熱可塑性樹脂フィルムを被覆したラミネート被覆材を缶体に成形して前記諸工程を省略する方法がとられるようになった。
【０００３】
【発明が解決しようとする課題】
しかし、前記ラミネート被覆材は、アルミニウム合金素材上に熱可塑性樹脂フィルムを被覆する際に、前記素材と熱可塑性樹脂フィルムとの間にミクロ気泡が生成するなどして熱可塑性樹脂フィルムの密着性が低下するという問題がある。このミクロ気泡発生の原因には、ラミネートを接着剤を介して被覆する場合は接着剤の濡れ性不足、接着剤の量不足、接着剤からの発泡などが考えられ、また圧着被覆する場合は圧着力の不足が考えられる。しかし、これら原因に対し各々対策を講じても気泡が発生する場合がある。
このため、本発明者等は、ミクロ気泡の生成防止について研究を行い、ミクロ気泡は前記素材の酸化皮膜厚さおよび表面粗さを規定することにより低減し得ることを見いだし、さらに種々研究を進めて本発明を完成させるに至った。
本発明は熱可塑性樹脂フィルムの密着性が優れたキャンボディ用アルミニウム合金ラミネート被覆材およびその製造方法の提供を目的とする。
【０００４】
【課題を解決するための手段】
請求項１記載の発明は、アルミニウム合金素材上に化成処理または陽極酸化処理のいずれかの処理による前処理皮膜が形成され、その上にラミネートフィルムが被覆されたキャンボディ用アルミニウム合金ラミネート被覆材において、前記アルミニウム合金素材の酸化皮膜厚さが２００Å以下、前処理皮膜の表面粗さが０．８ｍｍの基準長さにおいてＲａ０．３０μｍ以下、Ｒmax ２．０μｍ以下であることを特徴とするキャンボディ用アルミニウム合金ラミネート被覆材である。
【０００５】
請求項２記載の発明は、アルミニウム合金素材がＭｇを０．８〜１．５wt％、Ｍｎを０．２〜１．５wt％、Ｃｕを０．１〜０．５wt％含有し、残部がＡｌおよび不可避不純物からなるＡｌ合金素材であることを特徴とする請求項１記載のキャンボディ用アルミニウム合金ラミネート被覆材である。
【０００６】
請求項３記載の発明は、アルミニウム合金素材がＭｇを０．９〜１．２wt％、Ｍｎを０．２〜１．２wt％、Ｃｕを０．２〜０．３wt％含有し、残部がＡｌおよび不可避不純物からなるＡｌ合金素材であることを特徴とする請求項１記載のキャンボディ用アルミニウム合金ラミネート被覆材である。
【０００７】
請求項４記載の発明は、アルミニウム合金素材の厚さが２００〜３６０μｍであることを特徴とする請求項１、２、３のいずれかに記載のキャンボディ用アルミニウム合金ラミネート被覆材である。
【０００９】
請求項５記載の発明は、ラミネートフィルムの厚さが１０〜３０μｍであることを特徴とする請求項１、２、３又は４のいずれかに記載のキャンボディ用アルミニウム合金ラミネート被覆材である。
【００１０】
請求項６記載の発明は、ラミネートフィルムが、線圧力５ｋｇｆ／ｃｍ以上、２００〜３００℃の温度範囲の条件で熱圧着により被覆されていることを特徴とする請求項１、２、３、４又は５のいずれかに記載のキャンボディ用アルミニウム合金ラミネート被覆材である。
【００１１】
請求項７記載の発明は、アルミニウム合金鋳塊に均質化処理、熱間圧延、冷間圧延、必要に応じて熱間圧延後または冷間圧延中に焼鈍処理を施してアルミニウム合金素材を作製し、前記素材に化成処理または陽極酸化処理のいずれかの前処理を施し、次いで熱可塑性樹脂フィルムを被覆するキャンボディ用アルミニウム合金ラミネート被覆材の製造方法であって、前記冷間圧延の仕上げパスロールの表面粗さを０．８ｍｍの基準長さにおいてＲａ０．３０μｍ以下、Ｒmax ２．０μｍ以下とし、前処理前の素材の酸化皮膜厚さが２００Åを超える場合は、前処理前までに前記素材にアルカリまたは酸による洗浄処理を施して前記酸化皮膜厚さを２００Å以下にすることを特徴とする請求項１、２、３、４、５又は６のいずれかに記載のキャンボディ用アルミニウム合金ラミネート被覆材の製造方法である。
【００１２】
【発明の実施の形態】
請求項１記載の発明は、アルミニウム合金素材に化成皮膜などの前処理皮膜が形成され、その上に熱可塑性樹脂フィルム（以下ラミネートフィルムと記す）を被覆したラミネート被覆材の前記アルミニウム合金素材の酸化皮膜厚さを２００Å以下、前処理皮膜の表面粗さをＲａ０．３０μｍ以下、Ｒmax ２．０μｍ以下に規定したキャンボディ用アルミニウム合金ラミネート被覆材である。
【００１３】
この発明において、前記アルミニウム合金素材の酸化皮膜厚さを２００Å以下に規定する理由は、前記酸化皮膜厚さが２００Åを超えると酸化皮膜が脆くなり、前処理後またはラミネートフィルム形成後に破壊してラミネートフィルムの密着性が悪化するためである。前記酸化皮膜は前処理前にアルカリまたは酸で洗浄することにより薄くすることができる。
前記酸化皮膜厚さは、オージェ電子分光法（ＡＥＳ）により素材の酸素濃度を厚さ方向に線分析し、分析線のピーク値の半価幅で表わされる。
【００１４】
この発明において、前処理皮膜の表面粗さを基準長さ０．８ｍｍでＲａ０．３０μｍ以下、Ｒmax ２．０μｍ以下にそれぞれ規定する理由は、前記表面粗さが前記規定値を超えるとラミネートフィルム下にミクロ気泡が発生してラミネートフィルムの密着性が低下するためである。前記表面粗さは、冷間圧延の仕上げパスロールの表面粗さを小さくすることにより実現される。
【００１５】
本発明において、アルミニウム合金素材には、ある程度の引張強さと耐食性を有する任意の合金素材が適用されるが、特にＭｇを０．５〜５．０wt％、Ｍｎを０．２〜１．５wt％、Ｃｕを０．１〜０．５wt％含有し、残部がＡｌおよび不可避不純物からなるＡｌ合金素材はキャンボディに要求される強度や耐食性などを十分満足し望ましい。
【００１６】
以下に、前記アルミニウム合金素材の合金元素について説明する。
Ｍｇ、Ｍｎ、Ｃｕはいずれも素材の強度向上に寄与し、缶体の耐圧強度などを高める。前記Ｍｇ、Ｍｎ、Ｃｕの含有量をそれぞれ０．８〜１．５wt％、０．２〜１．５wt％、０．１〜０．５wt％に規定する理由は、前記元素の含有量が下限未満では、いずれも十分な強度が得られず、上限を超えると、ＭｇとＭｎはいずれも強度が高くなりすぎて、しごき成形性およびストレッチ加工性が低下して缶体に成形し難くなり、Ｃｕは耐食性が低下するためである。
Ｍｇ、Ｍｎ、Ｃｕの特に望ましい含有量は、それぞれ０．９〜１．２wt％、０．２〜１．２wt％、０．２〜０．３wt％である。
【００１７】
前記Ａｌ−Ｍｇ−Ｍｎ−Ｃｕ合金素材は、Ｔｉ、Ｂ、またはＣの合金元素を含有させることにより鋳造組織が微細化して加工性が改善される。
前記合金元素の望ましい含有量は、Ｔｉ０．００１〜０．０５wt％、Ｂ０．０００１〜０．０５wt％、Ｃ０．０００１〜０．０５wt％であり、前記各合金元素の含有量が下限未満ではいずれの元素も十分な微細化効果が得られず、上限を超えると、いずれも微細化効果が飽和してコスト的に不利なためである。さらにＴｉは粗大な晶出物が増加して缶体の成形性が低下する。
【００１８】
前記Ａｌ−Ｍｇ−Ｍｎ−Ｃｕ合金素材に含まれる不純物元素の許容限は、Ｓｉ０．４wt％、Ｆｅ０．５wt％、Ｚｎ０．５wt％、Ｃｒ０．１wt％、Ｚｒ０．１wt％、Ｖ０．１wt％である。その他の不純物元素も０．１wt％以下なら含まれていても差し支えない。
【００１９】
本発明において、アルミニウム合金素材の厚さは２００μｍ未満では十分な耐圧強度が得にくく、３６０μｍを超えるとコスト高になる。このためアルミニウム合金素材の厚さは２００〜３６０μｍが望ましい。
【００２０】
本発明において、前処理皮膜としては、化成皮膜または陽極酸化皮膜がラミネートフィルムとの密着性に優れ望ましい。
特に化成皮膜は、簡略な設備で形成でき、コスト的にも有利なため、工業上特に望ましいと言える。
化成皮膜は、リン酸亜鉛法、ベーマイト法、ＭＢＶ法、またはＥＷ法（アルカリ−クロム酸塩系）、アロヂン法（クロム酸塩系、リン酸−クロム酸塩系）などの化成処理により形成される。陽極酸化皮膜は、硫酸、しゅう酸、クロム酸、有機酸などの電解液を用いた陽極酸化処理により形成される。
【００２１】
本発明において、ラミネートフィルムの厚さは、１０μｍ未満ではフィルムが薄すぎて成形加工時に破れる恐れがあり、３０μｍを超えるとコスト高になる。このためラミネートフィルムの厚さは１０〜３０μｍが望ましい。
ラミネートフィルムが、線圧力５ｋｇｆ／ｃｍ未満で熱圧着されていると圧力不足から気泡が入ったり密着性が低下したりすることがある。また熱圧着温度が２００℃未満では十分良好な密着性が得られず、３００℃を超えるとフィルムが変質することがある。従って、ラミネートフィルムは、線圧力５ｋｇｆ／ｃｍ以上、２００〜３００℃の温度範囲の条件で熱圧着され被覆されていることが望ましい。
【００２２】
本発明において、ラミネートフィルムには、ポリエチレンテレフタレートなどのポリエステル系フィルム、ポリプロピレンやポリエチレンなどのポリオレフィン系フィルム、ナイロンなどのポリアミド系フィルムなどの通常使用されるフィルムが用いられる。これらフィルムは熱圧着またはプライマーを介した接着などにより被覆される。
【００２３】
本発明のラミネート被覆材は、例えば、Ａｌ−０．５〜５．０wt％Ｍｇ−０．２〜１．５wt％Ｍｎ−０．１〜０．５wt％Ｃｕ合金鋳塊に、均質化処理、熱間圧延、冷間圧延、必要に応じて熱間圧延後または冷間圧延中に焼鈍処理を施し、その後、前処理を施し、次いでラミネートフィルムを被覆して製造される。
【００２４】
請求項７記載の発明において、冷間圧延の仕上げパスロールの表面粗さを０．８ｍｍの基準長さにおいてＲａ０．３０μｍ以下、Ｒmax ２．０μｍ以下に規定する理由は、前記規定値を超えるとラミネートフィルム被覆前の素材の表面粗さが本発明規定値以下にならないためである。なお、冷間圧延後の素材の表面粗さは、洗浄処理後も、前処理後も、洗浄処理と前処理の両方を行ったあとも、ほぼ同じ粗さになるものである。
【００２５】
請求項７記載の発明において、前記焼鈍処理は、ＣＡＬ（連続焼鈍炉による焼鈍）、バッチ焼鈍などの任意の方法で施される。前記焼鈍処理により、素材の結晶方位が調整され、或いは加工歪みが除去される。大気中でバッチ焼鈍する場合は素材の酸化皮膜が厚く形成される。焼鈍処理は行わない場合もある。
【００２６】
請求項７記載の発明では、前処理前の素材の酸化皮膜の厚さが２００Åを超えて厚い場合はアルカリまたは酸による洗浄処理を施して酸化被膜を薄くする。洗浄処理は酸化皮膜厚さが２００Å以下のときに行って、酸化皮膜をさらに薄くしても良い。この洗浄処理は前処理前までに行えば良く、焼鈍処理を施さない場合は熱間圧延後から前処理前までの間に、焼鈍処理を施す場合は最終焼鈍処理後から前処理前までの間に行う。なお、洗浄処理は、通常、前処理と一貫して行うことが多いが、酸化被膜が厚い場合（２００Åを超える場合）は前処理前に別工程で行うのが酸化皮膜厚さを十分薄くできて望ましい。
【００２７】
【実施例】
以下に本発明を実施例により詳細に説明する。
（実施例１）
表１に示す本発明規定内組成のＡｌ合金をＤＣ鋳造法により鋳造し、得られた鋳塊を５２０℃で１２ｈｒ均質化処理後、熱間圧延して厚さ２．５ｍｍの板材とした。この熱間圧延終了時の板材温度は３００℃であった。次に前記板材を連続焼鈍炉（ＣＡＬ）により、昇温速度６０℃/sec、保持条件４５０℃×０/sec、冷却速度３０℃/secの条件で焼鈍処理したのち、冷間圧延して厚さ０．３０ｍｍの板状素材に仕上げ、この素材にリン酸クロメート処理（前処理）を施してＣｒを１５mg／ｄｍ²の厚さに形成し、この上にポリエチレンテレフタレート系フィルムを２５０℃で熱圧着してラミネート被覆材を製造した。冷間圧延の仕上げパスロールの表面粗さをＲａ０．３０μｍ以下、Ｒmax ２．０μｍ以下とした。前記焼鈍処理はＣＡＬにより短時間で行ったため前処理前の酸化皮膜はいずれも４０〜７０Åと薄く、従って洗浄処理は行わなかった。
【００２８】
（比較例１）
表１に示す本発明規定外組成のＡｌ合金を用いた他は、実施例１と同じ方法によりラミネート被覆材を製造した。
【００２９】
（比較例２）
冷間圧延の仕上げパスロールの表面粗さをＲａ０．４５μｍ、Ｒmax ３．０μｍとした他は、実施例１と同じ方法によりラミネート被覆材を製造した。
【００３０】
前記ラミネート被覆材を、２００℃で２０分加熱後、ＤＩ(Drawing&Ironing) 成形により内径６６ｍｍ、側壁厚さ１００μｍ、側壁先端部厚さ１５０μｍの缶体に成形し、次の▲１▼〜▲８▼の特性を調べた。▲１▼前処理前の酸化皮膜厚さ、▲２▼フィルム被覆前の表面粗さ、▲３▼ベーク相当条件で加熱(200℃で20分) 後の機械的性質、▲４▼ＤＩ成形時の破胴発生数(n＝1000) 、▲５▼缶体の耐圧強度、▲６▼缶体のフランジ成形性、▲７▼缶体の耐食性、▲８▼フィルムの密着性（ミクロ気泡の有無など）。
前記▲１▼▲２▼▲５▼〜▲８▼の試験方法の概略を以下に記す。
▲１▼酸化皮膜厚さはオージェ電子分光法により測定した。▲２▼表面粗さはＪＩＳ−Ｂ−０６０１に準じて測定した。▲５▼耐圧強度は窒素ガスにより加圧して調べた。▲６▼フランジ成形性は缶体上端をトリミングし洗浄したのち４段のネッキング加工により開口部の内径ｄを５７ｍｍに縮小し、この開口部に角度９０°の円錐状治具を押し込み、開口部に割れが発生したときの開口部の内径Ｄを測定し、口径限界増加率Ｐを、Ｐ＝｛（Ｄ−ｄ）／ｄ｝×１００％の式により求めて評価した。▲７▼耐食性は缶体をＣｕ²⁺を１０ｐｐｍ含む水道水中に４週間浸漬後発生した孔食の深さを測定して評価した。孔食深さが５０μｍ未満を良好（○）、５０μｍ以上１２５μｍ未満をほぼ良好（△）、１２５μｍ以上を不良（×）と評価した。▲８▼フィルムの密着性は上端をトリミングした缶体を１２０℃の熱水に３０分間浸漬し、フィルムの剥がれが全く生じなかったものを良好（○）、剥がれが生じたものを不良（×）と評価した。結果を表２に示す。
【００３１】
【表１】

【００３２】
【表２】

（注）酸膜厚：酸化皮膜厚さμｍ、表面粗さ：μｍ、
ＴＳ：引張強さ MPa、ＹＳ：0.2%耐力 MPa、Ｅlo：伸び％、
耐圧強度:kgf/cm²、フランジ成形性：口径限界増加率％。
【００３３】
表２より明らかなように、本発明例のNo.1〜6 は、いずれも、素材の酸化皮膜が薄く、前処理皮膜の表面粗さが小さいためラミネートフィルムの密着性が優れた。またキャンボディに必要な他の特性も満足した。中でも、Ｔｉ、Ｂ、Ｃなどを添加したもの (No.4〜6)は圧延加工性が良好で表面品質が特に優れた。
これに対し、比較例のNo.7〜9 は、合金元素が多いためいずれも加工性に劣りＤＩ成形時に多数の破胴があった。さらにNo.7はＣｕが多いため耐食性にも劣った。No.10 は表面粗さが粗いため密着性が劣った。
【００３４】
（実施例２）
表１の合金NoＦのアルミニウム合金鋳塊に、熱間圧延、焼鈍処理、冷間圧延を施して厚さ０．３０ｍｍの板状素材を作製した。冷間圧延の仕上げパスロールの表面粗さをＲａ０．３０μｍ以下、Ｒmax ２．０μｍ以下とした。前記焼鈍処理はＣＡＬにより短時間で行ったため前処理前の酸化皮膜はいずれも５０〜７０Åと薄く、従って洗浄処理は行わなかった。
次いで、前記素材にリン酸クロメート処理を施してＣｒを１５mg／ｄｍ²の厚さに形成し、この上にポリエチレンテレフタレート系フィルムを熱圧着（２５０℃で０秒）してしてラミネート被覆材を製造した。
【００３５】
（実施例３）
焼鈍処理を大気中でバッチ焼鈍で行い、バッチ焼鈍後の酸化皮膜が２２０Åと厚かったので前処理前に洗浄処理を行い、その後フィルムを２４０℃０秒の条件で熱圧着した。その他は、実施例２と同じ方法によりラミネート被覆材を製造した。前記洗浄処理は、液温７０℃のアルカリ液（ＰＨ１１）に３０秒間浸漬して施した。
【００３６】
（実施例４）
焼鈍処理および洗浄処理を行わなかった他は、実施例３と同じ方法によりラミネート被覆材を製造した。
【００３７】
（比較例３）
洗浄処理を行わなかった他は、実施例３と同じ方法によりラミネート被覆材を製造した。
【００３８】
実施例２〜４および比較例３で得られた各々のラミネート被覆材について実施例１と同じ方法でキャンボディに必要な諸特性を調べた。結果を表４に示す。
【００３９】
【表３】

（注）製法 No.１、２は実施例２、 No.３は実施例３、 No.４は実施例４、 No.５は比較例３。※比較例。
【００４０】
【表４】

（注）酸膜厚：酸化皮膜厚さμｍ(No.14は洗浄処理後の厚さ) 、
表面粗さ：μｍ、ＴＳ：引張強さ MPa、ＹＳ：0.2%耐力 MPa、Ｅlo：伸び％、
耐圧強度:kgf/cm²、フランジ成形性：口径限界増加率％。※比較例。
【００４１】
表４より明らかなように、本発明例の No.11〜14は、いずれも、酸化皮膜が薄く、表面粗さが小さいためミクロ気泡が存在しないでラミネートフィルムの密着性が優れ、またキャンボディに必要な他の特性も満足した。
比較例のNo.15 は洗浄処理を施さなかったため、前処理前の酸化被膜が厚くなりラミネートフィルムの密着性が低下した。
【００４２】
【発明の効果】
以上に述べたように、本発明のキャンボディ用アルミニウム合金ラミネート被覆材は、素材の酸化皮膜が薄く、また前処理皮膜の表面粗さが小さいため、ラミネートフィルムの密着性が優れ、剥がれなどの問題が生じない。前記素材の酸化皮膜はアルカリまたは酸で洗浄処理することで容易に薄くでき、前記前処理皮膜の表面粗さは冷間圧延の仕上げパスロールの表面粗さを小さくすることで容易に小さくできる。依って、工業上顕著な効果を奏する。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aluminum alloy laminate coating material for a can body having excellent adhesion of a thermoplastic resin film and a method for producing the same.
[0002]
[Prior art]
The beverage cans include a three-piece can composed of a can body, a can lid and a bottom cover, and a two-piece can composed of a can body and a can lid formed by integrating the can body and the bottom cover. Of these, squeezed and ironed cans (DI cans) and squeezed and redrawn cans (DRD cans) are often used for the two-piece cans. Recently, thin-walled redrawn cans that are stretched after squeezing have been developed. By the way, in the manufacture of DI cans, various processes such as washing, drying, and painting of lubricants have been performed after molding of cans. In recent years, thermoplastic resin films have been used to improve productivity and work environment. A method has been adopted in which the laminate coating material coated with is formed into a can body and the above steps are omitted.
[0003]
[Problems to be solved by the invention]
However, when the laminate coating material coats the thermoplastic resin film on the aluminum alloy material, the adhesiveness of the thermoplastic resin film is improved by generating micro bubbles between the material and the thermoplastic resin film. There is a problem of lowering. The cause of this microbubble generation may be insufficient wettability of the adhesive, insufficient amount of adhesive, foaming from the adhesive, etc. when the laminate is coated with an adhesive. There may be a lack of power. However, even if measures are taken for each of these causes, bubbles may be generated.
For this reason, the present inventors conducted research on the prevention of the formation of microbubbles, found that microbubbles can be reduced by defining the oxide film thickness and surface roughness of the material, and further advanced various studies. The present invention has been completed.
An object of the present invention is to provide an aluminum alloy laminate coating material for a can body having excellent adhesion of a thermoplastic resin film and a method for producing the same.
[0004]
[Means for Solving the Problems]
The invention according to claim 1 is an aluminum alloy laminate covering material for a can body in which a pretreatment film is formed on an aluminum alloy material by either chemical conversion treatment or anodizing treatment, and a laminate film is coated thereon. The aluminum alloy material has an oxide film thickness of 200 mm or less, and the surface roughness of the pretreatment film is Ra 0.30 μm or less and Rmax 2.0 μm or less at a reference length of 0.8 mm. It is an aluminum alloy laminate coating material.
[0005]
In the invention of claim 2, the aluminum alloy material contains 0.8 to 1.5 wt% Mg, 0.2 to 1.5 wt% Mn, 0.1 to 0.5 wt% Cu, and the balance is Al. The aluminum alloy laminate coating material for can bodies according to claim 1, wherein the aluminum alloy laminate coating material is an Al alloy material made of inevitable impurities.
[0006]
In the invention of claim 3, the aluminum alloy material contains 0.9 to 1.2 wt% Mg, 0.2 to 1.2 wt% Mn, 0.2 to 0.3 wt% Cu, and the balance is Al. The aluminum alloy laminate coating material for can bodies according to claim 1, wherein the aluminum alloy laminate coating material is an Al alloy material made of inevitable impurities.
[0007]
The invention according to claim 4 is the aluminum alloy laminate covering material for can bodies according to any one of claims 1, 2, and 3, wherein the aluminum alloy material has a thickness of 200 to 360 μm.
[0009]
The invention according to claim 5 is the aluminum alloy laminate coating material for a can body according to any one of claims 1, 2, 3 or 4, wherein the thickness of the laminate film is 10 to 30 μm.
[0010]
The invention described in claim 6 is characterized in that the laminate film is coated by thermocompression bonding under conditions of a linear pressure of 5 kgf / cm or more and a temperature range of 200 to 300 ° C. Or an aluminum alloy laminate coating material for a can body according to any one of 5 ;
[0011]
The invention according to claim 7 is to produce an aluminum alloy material by subjecting an aluminum alloy ingot to homogenization treatment, hot rolling, cold rolling, and if necessary, annealing treatment after hot rolling or during cold rolling. , A method for producing an aluminum alloy laminate coating material for a can body, wherein the material is subjected to a pretreatment of either chemical conversion treatment or anodizing treatment, and then coated with a thermoplastic resin film, comprising: If the surface roughness is Ra 0.30 μm or less and Rmax 2.0 μm or less at a standard length of 0.8 mm, and the oxide film thickness of the material before pretreatment exceeds 200 mm, the material is alkalinized before pretreatment. or claim 1, 2, 3, 4, characterized in that the cleaning treatment alms the oxide film thickness in the 200Å or less with an acid, Kyanbo according to any one of 5 or 6 It is a manufacturing method of I aluminum alloy laminate dressing.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 is an oxidation of the aluminum alloy material of a laminate coating material in which a pretreatment film such as a chemical conversion film is formed on an aluminum alloy material and a thermoplastic resin film (hereinafter referred to as a laminate film) is coated thereon. An aluminum alloy laminate coating material for a can body, in which the film thickness is 200 mm or less, and the surface roughness of the pretreatment film is Ra 0.30 μm or less and Rmax 2.0 μm or less.
[0013]
In this invention, the reason why the thickness of the oxide film of the aluminum alloy material is specified to be 200 mm or less is that when the thickness of the oxide film exceeds 200 mm, the oxide film becomes brittle and is destroyed after pretreatment or after the lamination film is formed. This is because the adhesion of the film is deteriorated. The oxide film can be thinned by washing with alkali or acid before pretreatment.
The thickness of the oxide film is represented by the half-value width of the peak value of the analytical line obtained by performing a line analysis of the oxygen concentration of the material in the thickness direction by Auger electron spectroscopy (AES).
[0014]
In the present invention, the surface roughness of the pretreatment film is specified to be Ra 0.30 μm or less and Rmax 2.0 μm or less at a reference length of 0.8 mm, respectively. This is because microbubbles are generated and the adhesion of the laminate film is lowered. The surface roughness is realized by reducing the surface roughness of a finish pass roll for cold rolling.
[0015]
In the present invention, any alloy material having a certain degree of tensile strength and corrosion resistance is applied to the aluminum alloy material, and in particular, Mg is 0.5 to 5.0 wt%, and Mn is 0.2 to 1.5 wt%. An Al alloy material containing 0.1 to 0.5 wt% of Cu and the balance of Al and inevitable impurities is desirable because it sufficiently satisfies the strength and corrosion resistance required for the can body.
[0016]
The alloy elements of the aluminum alloy material will be described below.
Mg, Mn, and Cu all contribute to improving the strength of the material and increase the pressure resistance of the can body. The reason why the contents of Mg, Mn, and Cu are regulated to 0.8 to 1.5 wt%, 0.2 to 1.5 wt%, and 0.1 to 0.5 wt%, respectively, is that the content of the element is the lower limit. If less than, sufficient strength is not obtained, and if the upper limit is exceeded, both Mg and Mn are too strong, and the ironing formability and stretch processability are reduced, making it difficult to form a can body. This is because Cu decreases the corrosion resistance.
Particularly desirable contents of Mg, Mn, and Cu are 0.9 to 1.2 wt%, 0.2 to 1.2 wt%, and 0.2 to 0.3 wt%, respectively.
[0017]
When the Al—Mg—Mn—Cu alloy material contains Ti, B, or C alloy elements, the cast structure is refined and the workability is improved.
Desirable contents of the alloy elements are Ti 0.001 to 0.05 wt%, B 0.0001 to 0.05 wt%, and C 0.0001 to 0.05 wt%. If the contents of the alloy elements are less than the lower limit, This is because the above element cannot obtain a sufficient refining effect, and if it exceeds the upper limit, the refining effect is saturated, which is disadvantageous in cost. Further, Ti increases the coarse crystallized product and lowers the moldability of the can.
[0018]
The allowable limits of impurity elements contained in the Al—Mg—Mn—Cu alloy material are Si 0.4 wt%, Fe 0.5 wt%, Zn 0.5 wt%, Cr 0.1 wt%, Zr 0.1 wt%, V 0.1 wt%. is there. Other impurity elements may be included if they are 0.1 wt% or less.
[0019]
In the present invention, if the thickness of the aluminum alloy material is less than 200 μm, it is difficult to obtain sufficient pressure resistance, and if it exceeds 360 μm, the cost increases. For this reason, the thickness of the aluminum alloy material is desirably 200 to 360 μm.
[0020]
In the present invention, as the pretreatment film, a chemical conversion film or an anodized film is preferable because of its excellent adhesion to the laminate film.
In particular, the chemical conversion film can be formed with simple equipment and is advantageous in terms of cost.
The chemical conversion film is formed by chemical conversion treatment such as zinc phosphate method, boehmite method, MBV method, EW method (alkali-chromate system), allodyne method (chromate system, phosphate-chromate system), etc. The The anodized film is formed by an anodizing process using an electrolytic solution such as sulfuric acid, oxalic acid, chromic acid, or organic acid.
[0021]
In the present invention, if the thickness of the laminate film is less than 10 μm, the film is too thin and may be broken during molding, and if it exceeds 30 μm, the cost increases. For this reason, the thickness of the laminate film is desirably 10 to 30 μm.
If the laminate film is thermocompression bonded at a linear pressure of less than 5 kgf / cm, bubbles may enter due to insufficient pressure or adhesion may be reduced. Further, when the thermocompression bonding temperature is less than 200 ° C., sufficiently good adhesion cannot be obtained, and when it exceeds 300 ° C., the film may be deteriorated. Therefore, it is desirable that the laminate film be coated by thermocompression bonding under conditions of a linear pressure of 5 kgf / cm or more and a temperature range of 200 to 300 ° C.
[0022]
In the present invention, as the laminate film, a commonly used film such as a polyester film such as polyethylene terephthalate, a polyolefin film such as polypropylene or polyethylene, or a polyamide film such as nylon is used. These films are coated by thermocompression bonding or adhesion via a primer.
[0023]
The laminate coating material of the present invention is, for example, an Al-0.5 to 5.0 wt% Mg-0.2 to 1.5 wt% Mn-0.1 to 0.5 wt% Cu alloy ingot, homogenized, It is manufactured by performing hot rolling, cold rolling, and if necessary, annealing treatment after hot rolling or during cold rolling, followed by pretreatment and then coating with a laminate film.
[0024]
In the invention of claim 7, the reason why the surface roughness of the finish pass roll for cold rolling is specified to be Ra 0.30 μm or less and Rmax 2.0 μm or less at a reference length of 0.8 mm is that the laminate exceeds the specified value. This is because the surface roughness of the material before film coating does not fall below the specified value of the present invention. In addition, the surface roughness of the raw material after the cold rolling is substantially the same after the cleaning process, after the pre-processing, and after both the cleaning process and the pre-processing.
[0025]
In the invention according to claim 7 , the annealing treatment is performed by an arbitrary method such as CAL (annealing by a continuous annealing furnace) or batch annealing. By the annealing treatment, the crystal orientation of the material is adjusted or the processing strain is removed. When batch annealing is performed in the atmosphere, a thick oxide film is formed. An annealing process may not be performed.
[0026]
In the invention according to claim 7, when the thickness of the oxide film of the material before the pretreatment is more than 200 mm, the oxide film is thinned by performing a cleaning treatment with an alkali or an acid. The cleaning treatment may be performed when the oxide film thickness is 200 mm or less to further reduce the oxide film. This cleaning treatment may be performed before the pretreatment. If no annealing treatment is performed, it is performed after the hot rolling until before the pretreatment, and if an annealing treatment is performed, after the final annealing treatment and before the pretreatment. To do. The cleaning treatment is usually performed consistently with the pretreatment, but when the oxide film is thick (in excess of 200 mm), it is possible to reduce the oxide film thickness sufficiently by performing it in a separate process before the pretreatment. Is desirable.
[0027]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples.
(Example 1)
An Al alloy having the composition defined in the present invention shown in Table 1 was cast by a DC casting method, and the obtained ingot was homogenized at 520 ° C. for 12 hours and then hot-rolled to obtain a plate material having a thickness of 2.5 mm. The plate material temperature at the end of the hot rolling was 300 ° C. Next, the plate material was annealed in a continuous annealing furnace (CAL) under the conditions of a heating rate of 60 ° C./sec, a holding condition of 450 ° C. × 0 / sec, and a cooling rate of 30 ° C./sec, and then cold-rolled and thickened. A 0.30 mm thick plate-like material is finished, and this material is subjected to phosphoric acid chromate treatment (pretreatment) to form Cr with a thickness of 15 mg / dm ² , and a polyethylene terephthalate film is heated at 250 ° C. The laminate coating material was manufactured by pressure bonding. The surface roughness of the finish pass roll for cold rolling was set to Ra 0.30 μm or less and Rmax 2.0 μm or less. Since the annealing treatment was performed in a short time by CAL, all the oxide films before the pretreatment were as thin as 40 to 70 mm, and therefore no washing treatment was performed.
[0028]
(Comparative Example 1)
A laminate coating material was produced in the same manner as in Example 1 except that an Al alloy having a composition outside the scope of the present invention shown in Table 1 was used.
[0029]
(Comparative Example 2)
A laminate coating material was produced in the same manner as in Example 1 except that the surface roughness of the finish pass roll of cold rolling was Ra 0.45 μm and Rmax 3.0 μm.
[0030]
The laminate coating material is heated at 200 ° C. for 20 minutes, and then formed into a can body having an inner diameter of 66 mm, a side wall thickness of 100 μm, and a side wall tip portion thickness of 150 μm by DI (Drawing & Ironing) molding, and the following (1) to (8) The characteristics of were investigated. (1) Thickness of oxide film before pretreatment, (2) Surface roughness before film coating, (3) Mechanical properties after heating under conditions equivalent to baking (20 minutes at 200 ° C), (4) During DI molding Number of broken shells (n = 1000), (5) pressure resistance of can body, (6) flange formability of can body, (7) corrosion resistance of can body, (8) adhesion of film (presence of microbubbles) Such).
The outline of the test methods (1), (2), (5) to (8) will be described below.
(1) The oxide film thickness was measured by Auger electron spectroscopy. (2) The surface roughness was measured according to JIS-B-0601. (5) The pressure strength was examined by pressurizing with nitrogen gas. (6) Flange formability is achieved by trimming the upper end of the can body and washing it, then reducing the inner diameter d of the opening to 57 mm by four steps of necking, and pressing a conical jig with an angle of 90 ° into this opening. The inner diameter D of the opening when cracking occurred was measured, and the aperture limit increase rate P was determined and evaluated by the formula P = {(D−d) / d} × 100%. (7) Corrosion resistance was evaluated by measuring the depth of pitting corrosion that occurred after the can body was immersed in tap water containing 10 ppm of Cu ²⁺ for 4 weeks. The pitting corrosion depth was evaluated as good (◯) when the pitting depth was less than 50 μm, almost good (Δ) when 50 μm or more and less than 125 μm, and bad (×) when 125 μm or more. (8) The adhesion of the film was obtained by immersing a can body trimmed at the upper end in hot water at 120 ° C. for 30 minutes, where the film did not peel off at all (good), and when the film peeled off was poor (× ). The results are shown in Table 2.
[0031]
[Table 1]

[0032]
[Table 2]

(Note) Acid film thickness: oxide film thickness μm, surface roughness: μm,
TS: Tensile strength MPa, YS: 0.2% proof stress MPa, Elo: Elongation%
Pressure resistance: kgf / cm ² , Flange formability: Diameter limit increase rate%.
[0033]
As is clear from Table 2, all of Nos. 1 to 6 of the examples of the present invention were excellent in the adhesiveness of the laminate film because the raw oxide film was thin and the surface roughness of the pretreatment film was small. It also satisfied other characteristics required for the can body. Among them, those added with Ti, B, C, etc. (Nos. 4 to 6) had good rolling processability and particularly excellent surface quality.
On the other hand, Nos. 7 to 9 of the comparative examples were inferior in workability because of many alloying elements, and had many broken bodies during DI molding. Furthermore, No. 7 was inferior in corrosion resistance due to a large amount of Cu. No. 10 had poor adhesion due to its rough surface.
[0034]
(Example 2)
The aluminum alloy ingot of alloy NoF in Table 1 was subjected to hot rolling, annealing treatment, and cold rolling to produce a plate-like material having a thickness of 0.30 mm. The surface roughness of the finish pass roll for cold rolling was set to Ra 0.30 μm or less and Rmax 2.0 μm or less. Since the annealing treatment was performed by CAL in a short time, the oxide film before the pretreatment was as thin as 50 to 70 mm, and therefore no washing treatment was performed.
Next, phosphoric acid chromate treatment is applied to the material to form Cr with a thickness of 15 mg / dm ² , and a polyethylene terephthalate film is thermocompression-bonded (250 ° C. for 0 second) to form a laminate coating material. Manufactured.
[0035]
(Example 3)
Annealing treatment was performed by batch annealing in the air, and the oxide film after batch annealing was as thick as 220 mm. Therefore, cleaning treatment was performed before pretreatment, and then the film was thermocompression bonded at 240 ° C. for 0 second. Otherwise, a laminate coating material was produced by the same method as in Example 2. The washing treatment was performed by immersing in an alkaline solution (PH11) having a liquid temperature of 70 ° C. for 30 seconds.
[0036]
(Example 4)
A laminate coating material was produced in the same manner as in Example 3 except that the annealing treatment and the cleaning treatment were not performed.
[0037]
(Comparative Example 3)
A laminate coating material was produced in the same manner as in Example 3 except that no washing treatment was performed.
[0038]
Various properties required for the can body were examined in the same manner as in Example 1 for each of the laminate coating materials obtained in Examples 2 to 4 and Comparative Example 3. The results are shown in Table 4.
[0039]
[Table 3]

(Note) Production method Nos. 1 and 2 are Example 2, No. 3 is Example 3, No. 4 is Example 4, and No. 5 is Comparative Example 3. * Comparison example.
[0040]
[Table 4]

(Note) Acid film thickness: Oxide film thickness μm (No.14 is the thickness after cleaning),
Surface roughness: μm, TS: Tensile strength MPa, YS: 0.2% proof stress MPa, Elo: Elongation%
Pressure resistance: kgf / cm ² , Flange formability: Diameter limit increase rate%. * Comparison example.
[0041]
As is apparent from Table 4, all of Nos. 11 to 14 of the present invention examples have a thin oxide film and a small surface roughness, so that microbubbles are not present and the adhesiveness of the laminate film is excellent. Satisfies other properties required for
Since No. 15 of the comparative example was not subjected to the cleaning treatment, the oxide film before the pretreatment became thick and the adhesiveness of the laminate film was lowered.
[0042]
【The invention's effect】
As described above, the aluminum alloy laminate coating material for can bodies of the present invention has a thin oxide film and a small surface roughness of the pretreatment film, so that the adhesiveness of the laminate film is excellent, and peeling There is no problem. The oxide film of the material can be easily thinned by washing with alkali or acid, and the surface roughness of the pretreatment film can be easily reduced by reducing the surface roughness of the finish pass roll of cold rolling. Therefore, there is an industrially significant effect.

Claims

An aluminum alloy laminate covering material for a can body, in which a pretreatment film is formed on an aluminum alloy material by either a chemical conversion treatment or an anodizing treatment, and a laminate film is coated thereon, an oxide film of the aluminum alloy material An aluminum alloy laminate covering material for a can body, wherein the thickness is 200 mm or less, and the surface roughness of the pretreatment film is Ra 0.30 μm or less and Rmax 2.0 μm or less at a reference length of 0.8 mm.

An aluminum alloy material containing 0.8 to 1.5 wt% Mg, 0.2 to 1.5 wt% Mn, 0.1 to 0.5 wt% Cu, the balance being Al and inevitable impurities The aluminum alloy laminate coating material for can bodies according to claim 1, wherein

Aluminum alloy material containing 0.9 to 1.2 wt% Mg, 0.2 to 1.2 wt% Mn, 0.2 to 0.3 wt% Cu, the balance being Al and inevitable impurities The aluminum alloy laminate coating material for can bodies according to claim 1, wherein

Aluminum alloy laminate covering material the can body according to any one of claims 1, 2 or 3 the thickness of the aluminum alloy material characterized in that it is a 200～360Myuemu.

The aluminum alloy laminate coating material for a can body according to any one of claims 1, 2, 3 and 4, wherein the laminate film has a thickness of 10 to 30 µm.

Laminate film, linear pressure 5 kgf / cm or more, according to any of claims 1, 2, 3, 4 or 5, characterized in that it is covered by thermocompression bonding under conditions of a temperature range of 200 to 300 [° C. Aluminum alloy laminate coating material for can bodies.

An aluminum alloy ingot is homogenized, hot-rolled, cold-rolled, and optionally subjected to an annealing treatment after hot-rolling or during cold-rolling to produce an aluminum alloy material. A method for producing an aluminum alloy laminate coating material for a can body, which is subjected to any pretreatment of an oxidation treatment and then coats a thermoplastic resin film, wherein the surface roughness of the finish pass roll of the cold rolling is 0.8 mm. If the reference length is Ra 0.30 μm or less and Rmax 2.0 μm or less, and the thickness of the oxide film before the pretreatment exceeds 200 mm, the material should be washed with alkali or acid before the pretreatment. claim 1, 2, 3, 4, the aluminum alloy for the can body according to any one of the 5 or 6, characterized in that the oxide film thickness 200Å or less Method for producing a laminate-coating material.